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File _service:download_files:0001-lrng-6.3-introduce-Linux-Random-Number-Generator.patch of Package linux-px (Revision b69819dc06160cdd2177e01aac5e07e7)

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From ece3edc98577853fe92eebad3c4dd467edd6fb70 Mon Sep 17 00:00:00 2001
From: Piotr Gorski <lucjan.lucjanov@gmail.com>
Date: Wed, 26 Apr 2023 11:40:33 +0200
Subject: [PATCH] lrng-6.3: introduce Linux Random Number Generator

Signed-off-by: Piotr Gorski <lucjan.lucjanov@gmail.com>
---
 MAINTAINERS                                   |   7 +
 crypto/drbg.c                                 |  16 +-
 drivers/char/Kconfig                          |   2 +
 drivers/char/Makefile                         |   5 +-
 drivers/char/lrng/Kconfig                     | 960 ++++++++++++++++++
 drivers/char/lrng/Makefile                    |  39 +
 drivers/char/lrng/lrng_definitions.h          | 163 +++
 drivers/char/lrng/lrng_drng_atomic.c          | 130 +++
 drivers/char/lrng/lrng_drng_atomic.h          |  23 +
 drivers/char/lrng/lrng_drng_chacha20.c        | 195 ++++
 drivers/char/lrng/lrng_drng_chacha20.h        |  42 +
 drivers/char/lrng/lrng_drng_drbg.c            | 179 ++++
 drivers/char/lrng/lrng_drng_drbg.h            |  13 +
 drivers/char/lrng/lrng_drng_kcapi.c           | 208 ++++
 drivers/char/lrng/lrng_drng_kcapi.h           |  13 +
 drivers/char/lrng/lrng_drng_mgr.c             | 742 ++++++++++++++
 drivers/char/lrng/lrng_drng_mgr.h             |  86 ++
 drivers/char/lrng/lrng_es_aux.c               | 335 ++++++
 drivers/char/lrng/lrng_es_aux.h               |  44 +
 drivers/char/lrng/lrng_es_cpu.c               | 281 +++++
 drivers/char/lrng/lrng_es_cpu.h               |  17 +
 drivers/char/lrng/lrng_es_irq.c               | 730 +++++++++++++
 drivers/char/lrng/lrng_es_irq.h               |  24 +
 drivers/char/lrng/lrng_es_jent.c              | 136 +++
 drivers/char/lrng/lrng_es_jent.h              |  17 +
 drivers/char/lrng/lrng_es_krng.c              | 100 ++
 drivers/char/lrng/lrng_es_krng.h              |  17 +
 drivers/char/lrng/lrng_es_mgr.c               | 506 +++++++++
 drivers/char/lrng/lrng_es_mgr.h               |  56 +
 drivers/char/lrng/lrng_es_mgr_cb.h            |  87 ++
 drivers/char/lrng/lrng_es_sched.c             | 566 +++++++++++
 drivers/char/lrng/lrng_es_sched.h             |  20 +
 drivers/char/lrng/lrng_es_timer_common.c      | 144 +++
 drivers/char/lrng/lrng_es_timer_common.h      |  83 ++
 drivers/char/lrng/lrng_hash_kcapi.c           | 140 +++
 drivers/char/lrng/lrng_health.c               | 447 ++++++++
 drivers/char/lrng/lrng_health.h               |  42 +
 drivers/char/lrng/lrng_interface_aux.c        | 209 ++++
 drivers/char/lrng/lrng_interface_dev.c        |  35 +
 drivers/char/lrng/lrng_interface_dev_common.c | 315 ++++++
 drivers/char/lrng/lrng_interface_dev_common.h |  51 +
 drivers/char/lrng/lrng_interface_hwrand.c     |  68 ++
 drivers/char/lrng/lrng_interface_kcapi.c      | 129 +++
 .../char/lrng/lrng_interface_random_kernel.c  | 248 +++++
 .../char/lrng/lrng_interface_random_kernel.h  |  17 +
 .../char/lrng/lrng_interface_random_user.c    | 104 ++
 drivers/char/lrng/lrng_numa.c                 | 124 +++
 drivers/char/lrng/lrng_numa.h                 |  15 +
 drivers/char/lrng/lrng_proc.c                 |  74 ++
 drivers/char/lrng/lrng_proc.h                 |  15 +
 drivers/char/lrng/lrng_selftest.c             | 397 ++++++++
 drivers/char/lrng/lrng_sha.h                  |  14 +
 drivers/char/lrng/lrng_sha1.c                 |  88 ++
 drivers/char/lrng/lrng_sha256.c               |  72 ++
 drivers/char/lrng/lrng_switch.c               | 286 ++++++
 drivers/char/lrng/lrng_sysctl.c               | 140 +++
 drivers/char/lrng/lrng_sysctl.h               |  15 +
 drivers/char/lrng/lrng_testing.c              | 901 ++++++++++++++++
 drivers/char/lrng/lrng_testing.h              |  85 ++
 include/crypto/drbg.h                         |   7 +
 include/linux/lrng.h                          | 251 +++++
 kernel/sched/core.c                           |   3 +
 62 files changed, 10271 insertions(+), 7 deletions(-)
 create mode 100644 drivers/char/lrng/Kconfig
 create mode 100644 drivers/char/lrng/Makefile
 create mode 100644 drivers/char/lrng/lrng_definitions.h
 create mode 100644 drivers/char/lrng/lrng_drng_atomic.c
 create mode 100644 drivers/char/lrng/lrng_drng_atomic.h
 create mode 100644 drivers/char/lrng/lrng_drng_chacha20.c
 create mode 100644 drivers/char/lrng/lrng_drng_chacha20.h
 create mode 100644 drivers/char/lrng/lrng_drng_drbg.c
 create mode 100644 drivers/char/lrng/lrng_drng_drbg.h
 create mode 100644 drivers/char/lrng/lrng_drng_kcapi.c
 create mode 100644 drivers/char/lrng/lrng_drng_kcapi.h
 create mode 100644 drivers/char/lrng/lrng_drng_mgr.c
 create mode 100644 drivers/char/lrng/lrng_drng_mgr.h
 create mode 100644 drivers/char/lrng/lrng_es_aux.c
 create mode 100644 drivers/char/lrng/lrng_es_aux.h
 create mode 100644 drivers/char/lrng/lrng_es_cpu.c
 create mode 100644 drivers/char/lrng/lrng_es_cpu.h
 create mode 100644 drivers/char/lrng/lrng_es_irq.c
 create mode 100644 drivers/char/lrng/lrng_es_irq.h
 create mode 100644 drivers/char/lrng/lrng_es_jent.c
 create mode 100644 drivers/char/lrng/lrng_es_jent.h
 create mode 100644 drivers/char/lrng/lrng_es_krng.c
 create mode 100644 drivers/char/lrng/lrng_es_krng.h
 create mode 100644 drivers/char/lrng/lrng_es_mgr.c
 create mode 100644 drivers/char/lrng/lrng_es_mgr.h
 create mode 100644 drivers/char/lrng/lrng_es_mgr_cb.h
 create mode 100644 drivers/char/lrng/lrng_es_sched.c
 create mode 100644 drivers/char/lrng/lrng_es_sched.h
 create mode 100644 drivers/char/lrng/lrng_es_timer_common.c
 create mode 100644 drivers/char/lrng/lrng_es_timer_common.h
 create mode 100644 drivers/char/lrng/lrng_hash_kcapi.c
 create mode 100644 drivers/char/lrng/lrng_health.c
 create mode 100644 drivers/char/lrng/lrng_health.h
 create mode 100644 drivers/char/lrng/lrng_interface_aux.c
 create mode 100644 drivers/char/lrng/lrng_interface_dev.c
 create mode 100644 drivers/char/lrng/lrng_interface_dev_common.c
 create mode 100644 drivers/char/lrng/lrng_interface_dev_common.h
 create mode 100644 drivers/char/lrng/lrng_interface_hwrand.c
 create mode 100644 drivers/char/lrng/lrng_interface_kcapi.c
 create mode 100644 drivers/char/lrng/lrng_interface_random_kernel.c
 create mode 100644 drivers/char/lrng/lrng_interface_random_kernel.h
 create mode 100644 drivers/char/lrng/lrng_interface_random_user.c
 create mode 100644 drivers/char/lrng/lrng_numa.c
 create mode 100644 drivers/char/lrng/lrng_numa.h
 create mode 100644 drivers/char/lrng/lrng_proc.c
 create mode 100644 drivers/char/lrng/lrng_proc.h
 create mode 100644 drivers/char/lrng/lrng_selftest.c
 create mode 100644 drivers/char/lrng/lrng_sha.h
 create mode 100644 drivers/char/lrng/lrng_sha1.c
 create mode 100644 drivers/char/lrng/lrng_sha256.c
 create mode 100644 drivers/char/lrng/lrng_switch.c
 create mode 100644 drivers/char/lrng/lrng_sysctl.c
 create mode 100644 drivers/char/lrng/lrng_sysctl.h
 create mode 100644 drivers/char/lrng/lrng_testing.c
 create mode 100644 drivers/char/lrng/lrng_testing.h
 create mode 100644 include/linux/lrng.h

diff --git a/MAINTAINERS b/MAINTAINERS
index c6545eb54..feffa3c3e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11935,6 +11935,13 @@ F:	Documentation/litmus-tests/
 F:	Documentation/memory-barriers.txt
 F:	tools/memory-model/
 
+LINUX RANDOM NUMBER GENERATOR (LRNG) DRIVER
+M:	Stephan Mueller <smueller@chronox.de>
+S:	Maintained
+W:	https://www.chronox.de/lrng.html
+F:	drivers/char/lrng/
+F:	include/linux/lrng.h
+
 LIS3LV02D ACCELEROMETER DRIVER
 M:	Eric Piel <eric.piel@tremplin-utc.net>
 S:	Maintained
diff --git a/crypto/drbg.c b/crypto/drbg.c
index 982d4ca45..af571948e 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -115,7 +115,7 @@
  * the SHA256 / AES 256 over other ciphers. Thus, the favored
  * DRBGs are the latest entries in this array.
  */
-static const struct drbg_core drbg_cores[] = {
+const struct drbg_core drbg_cores[] = {
 #ifdef CONFIG_CRYPTO_DRBG_CTR
 	{
 		.flags = DRBG_CTR | DRBG_STRENGTH128,
@@ -192,6 +192,7 @@ static const struct drbg_core drbg_cores[] = {
 	},
 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
 };
+EXPORT_SYMBOL(drbg_cores);
 
 static int drbg_uninstantiate(struct drbg_state *drbg);
 
@@ -207,7 +208,7 @@ static int drbg_uninstantiate(struct drbg_state *drbg);
  * Return: normalized strength in *bytes* value or 32 as default
  *	   to counter programming errors
  */
-static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
+unsigned short drbg_sec_strength(drbg_flag_t flags)
 {
 	switch (flags & DRBG_STRENGTH_MASK) {
 	case DRBG_STRENGTH128:
@@ -220,6 +221,7 @@ static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
 		return 32;
 	}
 }
+EXPORT_SYMBOL(drbg_sec_strength);
 
 /*
  * FIPS 140-2 continuous self test for the noise source
@@ -1252,7 +1254,7 @@ static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
 }
 
 /* Free all substructures in a DRBG state without the DRBG state structure */
-static inline void drbg_dealloc_state(struct drbg_state *drbg)
+void drbg_dealloc_state(struct drbg_state *drbg)
 {
 	if (!drbg)
 		return;
@@ -1273,12 +1275,13 @@ static inline void drbg_dealloc_state(struct drbg_state *drbg)
 		drbg->fips_primed = false;
 	}
 }
+EXPORT_SYMBOL(drbg_dealloc_state);
 
 /*
  * Allocate all sub-structures for a DRBG state.
  * The DRBG state structure must already be allocated.
  */
-static inline int drbg_alloc_state(struct drbg_state *drbg)
+int drbg_alloc_state(struct drbg_state *drbg)
 {
 	int ret = -ENOMEM;
 	unsigned int sb_size = 0;
@@ -1359,6 +1362,7 @@ static inline int drbg_alloc_state(struct drbg_state *drbg)
 	drbg_dealloc_state(drbg);
 	return ret;
 }
+EXPORT_SYMBOL(drbg_alloc_state);
 
 /*************************************************************************
  * DRBG interface functions
@@ -1893,8 +1897,7 @@ static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
  *
  * return: flags
  */
-static inline void drbg_convert_tfm_core(const char *cra_driver_name,
-					 int *coreref, bool *pr)
+void drbg_convert_tfm_core(const char *cra_driver_name, int *coreref, bool *pr)
 {
 	int i = 0;
 	size_t start = 0;
@@ -1921,6 +1924,7 @@ static inline void drbg_convert_tfm_core(const char *cra_driver_name,
 		}
 	}
 }
+EXPORT_SYMBOL(drbg_convert_tfm_core);
 
 static int drbg_kcapi_init(struct crypto_tfm *tfm)
 {
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index 30fe9848d..dfb3a5666 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -423,4 +423,6 @@ config ADI
 	  and SSM (Silicon Secured Memory).  Intended consumers of this
 	  driver include crash and makedumpfile.
 
+source "drivers/char/lrng/Kconfig"
+
 endmenu
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 1b35d1724..0d56f0a24 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -3,7 +3,8 @@
 # Makefile for the kernel character device drivers.
 #
 
-obj-y				+= mem.o random.o
+obj-y				+= mem.o
+obj-$(CONFIG_RANDOM_DEFAULT_IMPL) += random.o
 obj-$(CONFIG_TTY_PRINTK)	+= ttyprintk.o
 obj-y				+= misc.o
 obj-$(CONFIG_ATARI_DSP56K)	+= dsp56k.o
@@ -45,3 +46,5 @@ obj-$(CONFIG_PS3_FLASH)		+= ps3flash.o
 obj-$(CONFIG_XILLYBUS_CLASS)	+= xillybus/
 obj-$(CONFIG_POWERNV_OP_PANEL)	+= powernv-op-panel.o
 obj-$(CONFIG_ADI)		+= adi.o
+
+obj-$(CONFIG_LRNG)		+= lrng/
diff --git a/drivers/char/lrng/Kconfig b/drivers/char/lrng/Kconfig
new file mode 100644
index 000000000..b001fd3c1
--- /dev/null
+++ b/drivers/char/lrng/Kconfig
@@ -0,0 +1,960 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Linux Random Number Generator configuration
+#
+
+config RANDOM_DEFAULT_IMPL
+	bool "Kernel RNG Default Implementation"
+	default y
+	help
+	  The default random number generator as provided with
+	  drivers/char/random.c is selected with this option.
+
+config LRNG_AUTO_SELECTED
+	bool
+	default y if !RANDOM_DEFAULT_IMPL
+	default n if RANDOM_DEFAULT_IMPL
+	select LRNG
+
+config LRNG
+	bool "Linux Random Number Generator"
+	default n
+	select CRYPTO_LIB_SHA256 if CRYPTO
+	help
+	  The Linux Random Number Generator (LRNG) generates entropy
+	  from different entropy sources. Each entropy source can
+	  be enabled and configured independently. The interrupt
+	  entropy source can be configured to be SP800-90B compliant.
+	  The entire LRNG can be configured to be SP800-90C compliant.
+	  Runtime-switchable cryptographic support is available.
+	  The LRNG delivers significant entropy during boot.
+
+	  The LRNG also provides compliance to SP800-90A/B/C.
+
+menu "Linux Random Number Generator Configuration"
+	depends on LRNG
+
+if LRNG
+
+config LRNG_SHA256
+	bool
+	default y if CRYPTO_LIB_SHA256
+
+config LRNG_SHA1
+	bool
+	default y if !CRYPTO_LIB_SHA256
+
+config LRNG_COMMON_DEV_IF
+	bool
+
+config LRNG_DRNG_ATOMIC
+	bool
+	select LRNG_DRNG_CHACHA20
+
+config LRNG_SYSCTL
+	bool
+	depends on SYSCTL
+
+config LRNG_RANDOM_IF
+	bool
+	default n if RANDOM_DEFAULT_IMPL
+	default y if !RANDOM_DEFAULT_IMPL
+	select LRNG_COMMON_DEV_IF
+	select LRNG_DRNG_ATOMIC
+	select LRNG_SYSCTL
+
+menu "Specific DRNG seeding strategies"
+
+config LRNG_AIS2031_NTG1_SEEDING_STRATEGY
+	bool "AIS 20/31 NTG.1 seeding strategy"
+	default n
+	help
+	  When enabling this option, two entropy sources must
+	  deliver 220 bits of entropy each to consider a DRNG
+	  as fully seeded. Any two entropy sources can be used
+	  to fulfill this requirement. If specific entropy sources
+	  shall not be capable of contributing to this seeding
+	  strategy, the respective entropy source must be configured
+	  to provide less than 220 bits of entropy.
+
+	  The strategy is consistent with the requirements for
+	  NTG.1 compliance in German AIS 20/31 draft from 2022
+	  and is only enforced with lrng_es_mgr.ntg1=1.
+
+	  Compliance with German AIS 20/31 from 2011 is always
+	  present when using /dev/random with the flag O_SYNC or
+	  getrandom(2) with GRND_RANDOM.
+
+	  If unsure, say N.
+
+endmenu # "Specific DRNG seeding strategies"
+
+menu "LRNG Interfaces"
+
+config LRNG_KCAPI_IF
+	tristate "Interface with Kernel Crypto API"
+	depends on CRYPTO_RNG
+	help
+	  The LRNG can be registered with the kernel crypto API's
+	  random number generator framework. This offers a random
+	  number generator with the name "lrng" and a priority that
+	  is intended to be higher than the existing RNG
+	  implementations.
+
+config LRNG_HWRAND_IF
+	tristate "Interface with Hardware Random Number Generator Framework"
+	depends on HW_RANDOM
+	select LRNG_DRNG_ATOMIC
+	help
+	  The LRNG can be registered with the hardware random number
+	  generator framework. This offers a random number generator
+	  with the name "lrng" that is accessible via the framework.
+	  For example it allows pulling data from the LRNG via the
+	  /dev/hwrng file.
+
+config LRNG_DEV_IF
+	bool "Character device file interface"
+	select LRNG_COMMON_DEV_IF
+	help
+	  The LRNG can create a character device file that operates
+	  identically to /dev/random including IOCTL, read and write
+	  operations.
+
+endmenu # "LRNG Interfaces"
+
+menu "Entropy Source Configuration"
+
+config LRNG_RUNTIME_ES_CONFIG
+	bool "Enable runtime configuration of entropy sources"
+	help
+	  When enabling this option, the LRNG provides the mechanism
+	  allowing to alter the entropy rate of each entropy source
+	  during boot time and runtime.
+
+	  Each entropy source allows its entropy rate changed with
+	  a kernel command line option. When not providing any
+	  option, the default specified during kernel compilation
+	  is applied.
+
+comment "Common Timer-based Entropy Source Configuration"
+
+config LRNG_IRQ_DFLT_TIMER_ES
+	bool
+
+config LRNG_SCHED_DFLT_TIMER_ES
+	bool
+
+config LRNG_TIMER_COMMON
+	bool
+
+choice
+	prompt "Default Timer-based Entropy Source"
+	default LRNG_IRQ_DFLT_TIMER_ES
+	depends on LRNG_TIMER_COMMON
+	help
+	  Select the timer-based entropy source that is credited
+	  with entropy. The other timer-based entropy sources may
+	  be operational and provide data, but are credited with no
+	  entropy.
+
+	config LRNG_IRQ_DFLT_TIMER_ES
+	bool "Interrupt Entropy Source"
+	depends on LRNG_IRQ
+	help
+	  The interrupt entropy source is selected as a timer-based
+	  entropy source to provide entropy.
+
+	config LRNG_SCHED_DFLT_TIMER_ES
+	bool "Scheduler Entropy Source"
+	depends on LRNG_SCHED
+	help
+	  The scheduler entropy source is selected as timer-based
+	  entropy source to provide entropy.
+endchoice
+
+choice
+	prompt "LRNG Entropy Collection Pool Size"
+	default LRNG_COLLECTION_SIZE_1024
+	depends on LRNG_TIMER_COMMON
+	help
+	  Select the size of the LRNG entropy collection pool
+	  storing data for the interrupt as well as the scheduler
+	  entropy sources without performing a compression
+	  operation. The larger the collection size is, the faster
+	  the average interrupt handling will be. The collection
+	  size represents the number of bytes of the per-CPU memory
+	  used to batch up entropy event data.
+
+	  The default value is good for regular operations. Choose
+	  larger sizes for servers that have no memory limitations.
+	  If runtime memory is precious, choose a smaller size.
+
+	  The collection size is unrelated to the entropy rate
+	  or the amount of entropy the LRNG can process.
+
+	config LRNG_COLLECTION_SIZE_32
+	depends on LRNG_CONTINUOUS_COMPRESSION_ENABLED
+	depends on !LRNG_SWITCHABLE_CONTINUOUS_COMPRESSION
+	depends on !CRYPTO_FIPS
+		bool "32 interrupt events"
+
+	config LRNG_COLLECTION_SIZE_256
+	depends on !CRYPTO_FIPS
+		bool "256 interrupt events"
+
+	config LRNG_COLLECTION_SIZE_512
+		bool "512 interrupt events"
+
+	config LRNG_COLLECTION_SIZE_1024
+		bool "1024 interrupt events (default)"
+
+	config LRNG_COLLECTION_SIZE_2048
+		bool "2048 interrupt events"
+
+	config LRNG_COLLECTION_SIZE_4096
+		bool "4096 interrupt events"
+
+	config LRNG_COLLECTION_SIZE_8192
+		bool "8192 interrupt events"
+
+endchoice
+
+config LRNG_COLLECTION_SIZE
+	int
+	default 32 if LRNG_COLLECTION_SIZE_32
+	default 256 if LRNG_COLLECTION_SIZE_256
+	default 512 if LRNG_COLLECTION_SIZE_512
+	default 1024 if LRNG_COLLECTION_SIZE_1024
+	default 2048 if LRNG_COLLECTION_SIZE_2048
+	default 4096 if LRNG_COLLECTION_SIZE_4096
+	default 8192 if LRNG_COLLECTION_SIZE_8192
+
+config LRNG_HEALTH_TESTS
+	bool "Enable internal entropy source online health tests"
+	depends on LRNG_TIMER_COMMON
+	help
+	  The online health tests applied to the interrupt entropy
+	  source and to the scheduler entropy source to validate
+	  the noise source at runtime for fatal errors. These tests
+	  include SP800-90B compliant tests which are invoked if
+	  the system is booted with fips=1. In case of fatal errors
+	  during active SP800-90B tests, the issue is logged and
+	  the noise data is discarded. These tests are required for
+	  full compliance of the interrupt entropy source with
+	  SP800-90B.
+
+	  If both, the scheduler and the interrupt entropy sources,
+	  are enabled, the health tests for both are applied
+	  independent of each other.
+
+	  If unsure, say Y.
+
+config LRNG_RCT_BROKEN
+	bool "SP800-90B RCT with dangerous low cutoff value"
+	depends on LRNG_HEALTH_TESTS
+	depends on BROKEN
+	default n
+	help
+	  This option enables a dangerously low SP800-90B repetitive
+	  count test (RCT) cutoff value which makes it very likely
+	  that the RCT is triggered to raise a self test failure.
+
+	  This option is ONLY intended for developers wanting to
+	  test the effectiveness of the SP800-90B RCT health test.
+
+	  If unsure, say N.
+
+config LRNG_APT_BROKEN
+	bool "SP800-90B APT with dangerous low cutoff value"
+	depends on LRNG_HEALTH_TESTS
+	depends on BROKEN
+	default n
+	help
+	  This option enables a dangerously low SP800-90B adaptive
+	  proportion test (APT) cutoff value which makes it very
+	  likely that the APT is triggered to raise a self test
+	  failure.
+
+	  This option is ONLY intended for developers wanting to
+	  test the effectiveness of the SP800-90B APT health test.
+
+	  If unsure, say N.
+
+# Default taken from SP800-90B sec 4.4.1 - significance level 2^-30
+config LRNG_RCT_CUTOFF
+	int
+	default 31 if !LRNG_RCT_BROKEN
+	default 1 if LRNG_RCT_BROKEN
+
+# Default taken from SP800-90B sec 4.4.1 - significance level 2^-80
+config LRNG_RCT_CUTOFF_PERMANENT
+	int
+	default 81 if !LRNG_RCT_BROKEN
+	default 2 if LRNG_RCT_BROKEN
+
+# Default taken from SP800-90B sec 4.4.2 - significance level 2^-30
+config LRNG_APT_CUTOFF
+	int
+	default 325 if !LRNG_APT_BROKEN
+	default 32 if LRNG_APT_BROKEN
+
+# Default taken from SP800-90B sec 4.4.2 - significance level 2^-80
+config LRNG_APT_CUTOFF_PERMANENT
+	int
+	default 371 if !LRNG_APT_BROKEN
+	default 33 if LRNG_APT_BROKEN
+
+comment "Interrupt Entropy Source"
+
+config LRNG_IRQ
+	bool "Enable Interrupt Entropy Source as LRNG Seed Source"
+	default y
+	depends on !RANDOM_DEFAULT_IMPL
+	select LRNG_TIMER_COMMON
+	help
+	  The LRNG models an entropy source based on the timing of the
+	  occurrence of interrupts. Enable this option to enable this
+	  IRQ entropy source.
+
+	  The IRQ entropy source is triggered every time an interrupt
+	  arrives and thus causes the interrupt handler to execute
+	  slightly longer. Disabling the IRQ entropy source implies
+	  that the performance penalty on the interrupt handler added
+	  by the LRNG is eliminated. Yet, this entropy source is
+	  considered to be an internal entropy source of the LRNG.
+	  Thus, only disable it if you ensured that other entropy
+	  sources are available that supply the LRNG with entropy.
+
+	  If you disable the IRQ entropy source, you MUST ensure
+	  one or more entropy sources collectively have the
+	  capability to deliver sufficient entropy with one invocation
+	  at a rate compliant to the security strength of the DRNG
+	  (usually 256 bits of entropy). In addition, if those
+	  entropy sources do not deliver sufficient entropy during
+	  first request, the reseed must be triggered from user
+	  space or kernel space when sufficient entropy is considered
+	  to be present.
+
+	  If unsure, say Y.
+
+choice
+	prompt "Continuous entropy compression boot time setting"
+	default LRNG_CONTINUOUS_COMPRESSION_ENABLED
+	depends on LRNG_IRQ
+	help
+	  Select the default behavior of the interrupt entropy source
+	  continuous compression operation.
+
+	  The LRNG IRQ ES collects entropy data during each interrupt.
+	  For performance reasons, a amount of entropy data defined by
+	  the LRNG entropy collection pool size is concatenated into
+	  an array. When that array is filled up, a hash is calculated
+	  to compress the entropy. That hash is calculated in
+	  interrupt context.
+
+	  In case such hash calculation in interrupt context is deemed
+	  too time-consuming, the continuous compression operation
+	  can be disabled. If disabled, the collection of entropy will
+	  not trigger a hash compression operation in interrupt context.
+	  The compression happens only when the DRNG is reseeded which is
+	  in process context. This implies that old entropy data
+	  collected after the last DRNG-reseed is overwritten with newer
+	  entropy data once the collection pool is full instead of
+	  retaining its entropy with the compression operation.
+
+	config LRNG_CONTINUOUS_COMPRESSION_ENABLED
+		bool "Enable continuous compression (default)"
+
+	config LRNG_CONTINUOUS_COMPRESSION_DISABLED
+		bool "Disable continuous compression"
+
+endchoice
+
+config LRNG_ENABLE_CONTINUOUS_COMPRESSION
+	bool
+	default y if LRNG_CONTINUOUS_COMPRESSION_ENABLED
+	default n if LRNG_CONTINUOUS_COMPRESSION_DISABLED
+
+config LRNG_SWITCHABLE_CONTINUOUS_COMPRESSION
+	bool "Runtime-switchable continuous entropy compression"
+	depends on LRNG_IRQ
+	help
+	  Per default, the interrupt entropy source continuous
+	  compression operation behavior is hard-wired into the kernel.
+	  Enable this option to allow it to be configurable at boot time.
+
+	  To modify the default behavior of the continuous
+	  compression operation, use the kernel command line option
+	  of lrng_sw_noise.lrng_pcpu_continuous_compression.
+
+	  If unsure, say N.
+
+config LRNG_IRQ_ENTROPY_RATE
+	int "Interrupt Entropy Source Entropy Rate"
+	depends on LRNG_IRQ
+	range 256 4294967295 if LRNG_IRQ_DFLT_TIMER_ES
+	range 4294967295 4294967295 if !LRNG_IRQ_DFLT_TIMER_ES
+	default 256 if LRNG_IRQ_DFLT_TIMER_ES
+	default 4294967295 if !LRNG_IRQ_DFLT_TIMER_ES
+	help
+	  The LRNG will collect the configured number of interrupts to
+	  obtain 256 bits of entropy. This value can be set to any between
+	  256 and 4294967295. The LRNG guarantees that this value is not
+	  lower than 256. This lower limit implies that one interrupt event
+	  is credited with one bit of entropy. This value is subject to the
+	  increase by the oversampling factor, if no high-resolution timer
+	  is found.
+
+	  In order to effectively disable the interrupt entropy source,
+	  the option has to be set to 4294967295. In this case, the
+	  interrupt entropy source will still deliver data but without
+	  being credited with entropy.
+
+comment "Jitter RNG Entropy Source"
+
+config LRNG_JENT
+	bool "Enable Jitter RNG as LRNG Seed Source"
+	depends on CRYPTO
+	select CRYPTO_JITTERENTROPY
+	help
+	  The LRNG may use the Jitter RNG as entropy source. Enabling
+	  this option enables the use of the Jitter RNG. Its default
+	  entropy level is 16 bits of entropy per 256 data bits delivered
+	  by the Jitter RNG. This entropy level can be changed at boot
+	  time or at runtime with the lrng_base.jitterrng configuration
+	  variable.
+
+config LRNG_JENT_ENTROPY_RATE
+	int "Jitter RNG Entropy Source Entropy Rate"
+	depends on LRNG_JENT
+	range 0 256
+	default 16
+	help
+	  The option defines the amount of entropy the LRNG applies to 256
+	  bits of data obtained from the Jitter RNG entropy source. The
+	  LRNG enforces the limit that this value must be in the range
+	  between 0 and 256.
+
+	  When configuring this value to 0, the Jitter RNG entropy source
+	  will provide 256 bits of data without being credited to contain
+	  entropy.
+
+comment "CPU Entropy Source"
+
+config LRNG_CPU
+	bool "Enable CPU Entropy Source as LRNG Seed Source"
+	default y
+	help
+	  Current CPUs commonly contain entropy sources which can be
+	  used to seed the LRNG. For example, the Intel RDSEED
+	  instruction, or the POWER DARN instruction will be sourced
+	  to seed the LRNG if this option is enabled.
+
+	  Note, if this option is enabled and the underlying CPU
+	  does not offer such entropy source, the LRNG will automatically
+	  detect this and ignore the hardware.
+
+config LRNG_CPU_FULL_ENT_MULTIPLIER
+	int
+	default 1 if !LRNG_TEST_CPU_ES_COMPRESSION
+	default 123 if LRNG_TEST_CPU_ES_COMPRESSION
+
+config LRNG_CPU_ENTROPY_RATE
+	int "CPU Entropy Source Entropy Rate"
+	depends on LRNG_CPU
+	range 0 256
+	default 8
+	help
+	  The option defines the amount of entropy the LRNG applies to 256
+	  bits of data obtained from the CPU entropy source. The LRNG
+	  enforces the limit that this value must be in the range between
+	  0 and 256.
+
+	  When configuring this value to 0, the CPU entropy source will
+	  provide 256 bits of data without being credited to contain
+	  entropy.
+
+	  Note, this option is overwritten when the option
+	  CONFIG_RANDOM_TRUST_CPU is set.
+
+comment "Scheduler Entropy Source"
+
+config LRNG_SCHED
+	bool "Enable Scheduer Entropy Source as LRNG Seed Source"
+	select LRNG_TIMER_COMMON
+	help
+	  The LRNG models an entropy source based on the timing of the
+	  occurrence of scheduler-triggered context switches. Enable
+	  this option to enable this scheduler entropy source.
+
+	  The scheduler entropy source is triggered every time a
+	  context switch is triggered thus causes the scheduler to
+	  execute slightly longer. Disabling the scheduler entropy
+	  source implies that the performance penalty on the scheduler
+	  added by the LRNG is eliminated. Yet, this entropy source is
+	  considered to be an internal entropy source of the LRNG.
+	  Thus, only disable it if you ensured that other entropy
+	  sources are available that supply the LRNG with entropy.
+
+	  If you disable the scheduler entropy source, you MUST
+	  ensure one or more entropy sources collectively have the
+	  capability to deliver sufficient entropy with one invocation
+	  at a rate compliant to the security strength of the DRNG
+	  (usually 256 bits of entropy). In addition, if those
+	  entropy sources do not deliver sufficient entropy during
+	  first request, the reseed must be triggered from user
+	  space or kernel space when sufficient entropy is considered
+	  to be present.
+
+	  If unsure, say Y.
+
+config LRNG_SCHED_ENTROPY_RATE
+	int "Scheduler Entropy Source Entropy Rate"
+	depends on LRNG_SCHED
+	range 256 4294967295 if LRNG_SCHED_DFLT_TIMER_ES
+	range 4294967295 4294967295 if !LRNG_SCHED_DFLT_TIMER_ES
+	default 256 if LRNG_SCHED_DFLT_TIMER_ES
+	default 4294967295 if !LRNG_SCHED_DFLT_TIMER_ES
+	help
+	  The LRNG will collect the configured number of context switches
+	  triggered by the scheduler to obtain 256 bits of entropy. This
+	  value can be set to any between 256 and 4294967295. The LRNG
+	  guarantees that this value is not lower than 256. This lower
+	  limit implies that one interrupt event is credited with one bit
+	  of entropy. This value is subject to the increase by the
+	  oversampling factor, if no high-resolution timer is found.
+
+	  In order to effectively disable the scheduler entropy source,
+	  the option has to be set to 4294967295. In this case, the
+	  scheduler entropy source will still deliver data but without
+	  being credited with entropy.
+
+comment "Kernel RNG Entropy Source"
+
+config LRNG_KERNEL_RNG
+	bool "Enable Kernel RNG as LRNG Seed Source"
+	depends on RANDOM_DEFAULT_IMPL
+	help
+	  The LRNG may use the kernel RNG (random.c) as entropy
+	  source.
+
+config LRNG_KERNEL_RNG_ENTROPY_RATE
+	int "Kernel RNG Entropy Source Entropy Rate"
+	depends on LRNG_KERNEL_RNG
+	range 0 256
+	default 256
+	help
+	  The option defines the amount of entropy the LRNG applies to 256
+	  bits of data obtained from the kernel RNG entropy source. The
+	  LRNG enforces the limit that this value must be in the range
+	  between 0 and 256.
+
+	  When configuring this value to 0, the kernel RNG entropy source
+	  will provide 256 bits of data without being credited to contain
+	  entropy.
+
+	  Note: This value is set to 0 automatically when booting the
+	  kernel in FIPS mode (with fips=1 kernel command line option).
+	  This is due to the fact that random.c is not SP800-90B
+	  compliant.
+
+endmenu # "Entropy Source Configuration"
+
+config LRNG_DRNG_CHACHA20
+	tristate
+
+config LRNG_DRBG
+	tristate
+	depends on CRYPTO
+	select CRYPTO_DRBG_MENU
+
+config LRNG_DRNG_KCAPI
+	tristate
+	depends on CRYPTO
+	select CRYPTO_RNG
+
+config LRNG_SWITCH
+	bool
+
+menuconfig LRNG_SWITCH_HASH
+	bool "Support conditioning hash runtime switching"
+	select LRNG_SWITCH
+	help
+	  The LRNG uses a default message digest. With this
+	  configuration option other message digests can be selected
+	  and loaded at runtime.
+
+if LRNG_SWITCH_HASH
+
+config LRNG_HASH_KCAPI
+	tristate "Kernel crypto API hashing support for LRNG"
+	select CRYPTO_HASH
+	select CRYPTO_SHA512
+	help
+	  Enable the kernel crypto API support for entropy compression
+	  and conditioning functions.
+
+endif # LRNG_SWITCH_HASH
+
+menuconfig LRNG_SWITCH_DRNG
+	bool "Support DRNG runtime switching"
+	select LRNG_SWITCH
+	help
+	  The LRNG uses a default DRNG With this configuration
+	  option other DRNGs or message digests can be selected and
+	  loaded at runtime.
+
+if LRNG_SWITCH_DRNG
+
+config LRNG_SWITCH_DRNG_CHACHA20
+	tristate "ChaCha20-based DRNG support for LRNG"
+	depends on !LRNG_DFLT_DRNG_CHACHA20
+	select LRNG_DRNG_CHACHA20
+	help
+	  Enable the ChaCha20-based DRNG. This DRNG implementation
+	  does not depend on the kernel crypto API presence.
+
+config LRNG_SWITCH_DRBG
+	tristate "SP800-90A support for the LRNG"
+	depends on !LRNG_DFLT_DRNG_DRBG
+	select LRNG_DRBG
+	help
+	  Enable the SP800-90A DRBG support for the LRNG. Once the
+	  module is loaded, output from /dev/random, /dev/urandom,
+	  getrandom(2), or get_random_bytes_full is provided by a DRBG.
+
+config LRNG_SWITCH_DRNG_KCAPI
+	tristate "Kernel Crypto API support for the LRNG"
+	depends on !LRNG_DFLT_DRNG_KCAPI
+	depends on !LRNG_SWITCH_DRBG
+	select LRNG_DRNG_KCAPI
+	help
+	  Enable the support for generic pseudo-random number
+	  generators offered by the kernel crypto API with the
+	  LRNG. Once the module is loaded, output from /dev/random,
+	  /dev/urandom, getrandom(2), or get_random_bytes is
+	  provided by the selected kernel crypto API RNG.
+
+endif # LRNG_SWITCH_DRNG
+
+choice
+	prompt "LRNG Default DRNG"
+	default LRNG_DFLT_DRNG_CHACHA20
+	help
+	  Select the default deterministic random number generator
+	  that is used by the LRNG. When enabling the switchable
+	  cryptographic mechanism support, this DRNG can be
+	  replaced at runtime.
+
+	config LRNG_DFLT_DRNG_CHACHA20
+		bool "ChaCha20-based DRNG"
+		select LRNG_DRNG_CHACHA20
+
+	config LRNG_DFLT_DRNG_DRBG
+		depends on RANDOM_DEFAULT_IMPL
+		bool "SP800-90A DRBG"
+		select LRNG_DRBG
+
+	config LRNG_DFLT_DRNG_KCAPI
+		depends on RANDOM_DEFAULT_IMPL
+		bool "Kernel Crypto API DRNG"
+		select LRNG_DRNG_KCAPI
+endchoice
+
+menuconfig LRNG_TESTING_MENU
+	bool "LRNG testing interfaces"
+	depends on DEBUG_FS
+	help
+	  Enable one or more of the following test interfaces.
+
+	  If unsure, say N.
+
+if LRNG_TESTING_MENU
+
+config LRNG_TESTING
+	bool
+
+config LRNG_TESTING_RECORDING
+	bool
+
+comment "Interrupt Entropy Source Test Interfaces"
+
+config LRNG_RAW_HIRES_ENTROPY
+	bool "Interface to obtain raw unprocessed IRQ noise source data"
+	default y
+	depends on LRNG_IRQ
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned high resolution time stamp noise that
+	  is collected by the LRNG for statistical analysis. Extracted
+	  noise data is not used to seed the LRNG.
+
+	  The raw noise data can be obtained using the lrng_raw_hires
+	  debugfs file. Using the option lrng_testing.boot_raw_hires_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_RAW_JIFFIES_ENTROPY
+	bool "Entropy test interface to Jiffies of IRQ noise source"
+	depends on LRNG_IRQ
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned Jiffies that is collected by
+	  the LRNG for statistical analysis. This data is used for
+	  seeding the LRNG if a high-resolution time stamp is not
+	  available. If a high-resolution time stamp is detected,
+	  the Jiffies value is not collected by the LRNG and no
+	  data is provided via the test interface. Extracted noise
+	  data is not used to seed the random number generator.
+
+	  The raw noise data can be obtained using the lrng_raw_jiffies
+	  debugfs file. Using the option lrng_testing.boot_raw_jiffies_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_RAW_IRQ_ENTROPY
+	bool "Entropy test interface to IRQ number noise source"
+	depends on LRNG_IRQ
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned interrupt number that is collected by
+	  the LRNG for statistical analysis. Extracted noise data is
+	  not used to seed the random number generator.
+
+	  The raw noise data can be obtained using the lrng_raw_irq
+	  debugfs file. Using the option lrng_testing.boot_raw_irq_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_RAW_RETIP_ENTROPY
+	bool "Entropy test interface to RETIP value of IRQ noise source"
+	depends on LRNG_IRQ
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned return instruction pointer value
+	  that is collected by the LRNG for statistical analysis.
+	  Extracted noise data is not used to seed the random number
+	  generator.
+
+	  The raw noise data can be obtained using the lrng_raw_retip
+	  debugfs file. Using the option lrng_testing.boot_raw_retip_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_RAW_REGS_ENTROPY
+	bool "Entropy test interface to IRQ register value noise source"
+	depends on LRNG_IRQ
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned interrupt register value that is
+	  collected by the LRNG for statistical analysis. Extracted noise
+	  data is not used to seed the random number generator.
+
+	  The raw noise data can be obtained using the lrng_raw_regs
+	  debugfs file. Using the option lrng_testing.boot_raw_regs_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_RAW_ARRAY
+	bool "Test interface to LRNG raw entropy IRQ storage array"
+	depends on LRNG_IRQ
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw noise data that is collected by the LRNG
+	  in the per-CPU array for statistical analysis. The purpose
+	  of this interface is to verify that the array handling code
+	  truly only concatenates data and provides the same entropy
+	  rate as the raw unconditioned noise source when assessing
+	  the collected data byte-wise.
+
+	  The data can be obtained using the lrng_raw_array debugfs
+	  file. Using the option lrng_testing.boot_raw_array=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_IRQ_PERF
+	bool "LRNG interrupt entropy source performance monitor"
+	depends on LRNG_IRQ
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  With this option, the performance monitor of the LRNG
+	  interrupt handling code is enabled. The file provides
+	  the execution time of the interrupt handler in
+	  cycles.
+
+	  The interrupt performance data can be obtained using
+	  the lrng_irq_perf debugfs file. Using the option
+	  lrng_testing.boot_irq_perf=1 the performance data of
+	  the first 1000 entropy events since boot can be sampled.
+
+comment "Scheduler Entropy Source Test Interfaces"
+
+config LRNG_RAW_SCHED_HIRES_ENTROPY
+	bool "Interface to obtain raw unprocessed scheduler noise source data"
+	depends on LRNG_SCHED
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned high resolution time stamp noise that
+	  is collected by the LRNG for the Scheduler-based noise source
+	  for statistical analysis. Extracted  noise data is not used to
+	  seed the LRNG.
+
+	  The raw noise data can be obtained using the lrng_raw_sched_hires
+	  debugfs file. Using the option
+	  lrng_testing.boot_raw_sched_hires_test=1 the raw noise of the
+	  first 1000 entropy events since boot can be sampled.
+
+config LRNG_RAW_SCHED_PID_ENTROPY
+	bool "Entropy test interface to PID value"
+	depends on LRNG_SCHED
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned PID value that is collected by the
+	  LRNG for statistical analysis. Extracted noise
+	  data is not used to seed the random number generator.
+
+	  The raw noise data can be obtained using the
+	  lrng_raw_sched_pid debugfs file. Using the option
+	  lrng_testing.boot_raw_sched_pid_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_RAW_SCHED_START_TIME_ENTROPY
+	bool "Entropy test interface to task start time value"
+	depends on LRNG_SCHED
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned task start time value that is collected
+	  by the LRNG for statistical analysis. Extracted noise
+	  data is not used to seed the random number generator.
+
+	  The raw noise data can be obtained using the
+	  lrng_raw_sched_starttime debugfs file. Using the option
+	  lrng_testing.boot_raw_sched_starttime_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+
+config LRNG_RAW_SCHED_NVCSW_ENTROPY
+	bool "Entropy test interface to task context switch numbers"
+	depends on LRNG_SCHED
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  The test interface allows a privileged process to capture
+	  the raw unconditioned task numbers of context switches that
+	  are collected by the LRNG for statistical analysis. Extracted
+	  noise data is not used to seed the random number generator.
+
+	  The raw noise data can be obtained using the
+	  lrng_raw_sched_nvcsw debugfs file. Using the option
+	  lrng_testing.boot_raw_sched_nvcsw_test=1
+	  the raw noise of the first 1000 entropy events since boot
+	  can be sampled.
+
+config LRNG_SCHED_PERF
+	bool "LRNG scheduler entropy source performance monitor"
+	depends on LRNG_SCHED
+	select LRNG_TESTING
+	select LRNG_TESTING_RECORDING
+	help
+	  With this option, the performance monitor of the LRNG
+	  scheduler event handling code is enabled. The file provides
+	  the execution time of the interrupt handler in cycles.
+
+	  The scheduler performance data can be obtained using
+	  the lrng_sched_perf debugfs file. Using the option
+	  lrng_testing.boot_sched_perf=1 the performance data of
+	  the first 1000 entropy events since boot can be sampled.
+
+comment "Auxiliary Test Interfaces"
+
+config LRNG_ACVT_HASH
+	bool "Enable LRNG ACVT Hash interface"
+	select LRNG_TESTING
+	help
+	  With this option, the LRNG built-in hash function used for
+	  auxiliary pool management and prior to switching the
+	  cryptographic backends is made available for ACVT. The
+	  interface allows writing of the data to be hashed
+	  into the interface. The read operation triggers the hash
+	  operation to generate message digest.
+
+	  The ACVT interface is available with the lrng_acvt_hash
+	  debugfs file.
+
+config LRNG_RUNTIME_MAX_WO_RESEED_CONFIG
+	bool "Enable runtime configuration of max reseed threshold"
+	help
+	  When enabling this option, the LRNG provides an interface
+	  allowing the setting of the maximum number of DRNG generate
+	  operations without a reseed that has full entropy. The
+	  interface is lrng_drng.max_wo_reseed.
+
+config LRNG_RUNTIME_FORCE_SEEDING_DISABLE
+	bool "Enable runtime configuration of force seeding"
+	help
+	  When enabling this option, the LRNG provides an interface
+	  allowing the disabling of the force seeding when the DRNG
+	  is not fully seeded but entropy is available.
+
+config LRNG_TEST_CPU_ES_COMPRESSION
+	bool "Force CPU ES compression operation"
+	help
+	  When enabling this option, the CPU ES compression operation
+	  is forced by setting an arbitrary value > 1 for the data
+	  multiplier even when the CPU ES would deliver full entropy.
+	  This allows testing of the compression operation. It
+	  therefore forces to pull more data from the CPU ES
+	  than what may be required.
+
+endif #LRNG_TESTING_MENU
+
+config LRNG_SELFTEST
+	bool "Enable power-on and on-demand self-tests"
+	help
+	  The power-on self-tests are executed during boot time
+	  covering the ChaCha20 DRNG, the hash operation used for
+	  processing the entropy pools and the auxiliary pool, and
+	  the time stamp management of the LRNG.
+
+	  The on-demand self-tests are triggered by writing any
+	  value into the SysFS file selftest_status. At the same
+	  time, when reading this file, the test status is
+	  returned. A zero indicates that all tests were executed
+	  successfully.
+
+	  If unsure, say Y.
+
+if LRNG_SELFTEST
+
+config LRNG_SELFTEST_PANIC
+	bool "Panic the kernel upon self-test failure"
+	help
+	  If the option is enabled, the kernel is terminated if an
+	  LRNG power-on self-test failure is detected.
+
+endif # LRNG_SELFTEST
+
+endif # LRNG
+
+endmenu # LRNG
diff --git a/drivers/char/lrng/Makefile b/drivers/char/lrng/Makefile
new file mode 100644
index 000000000..f61fc40f4
--- /dev/null
+++ b/drivers/char/lrng/Makefile
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Entropy Source and DRNG Manager.
+#
+
+obj-y					+= lrng_es_mgr.o lrng_drng_mgr.o \
+					   lrng_es_aux.o
+obj-$(CONFIG_LRNG_SHA256)		+= lrng_sha256.o
+obj-$(CONFIG_LRNG_SHA1)			+= lrng_sha1.o
+
+obj-$(CONFIG_SYSCTL)			+= lrng_proc.o
+obj-$(CONFIG_LRNG_SYSCTL)		+= lrng_sysctl.o
+obj-$(CONFIG_NUMA)			+= lrng_numa.o
+
+obj-$(CONFIG_LRNG_SWITCH)		+= lrng_switch.o
+obj-$(CONFIG_LRNG_HASH_KCAPI)		+= lrng_hash_kcapi.o
+obj-$(CONFIG_LRNG_DRNG_CHACHA20)	+= lrng_drng_chacha20.o
+obj-$(CONFIG_LRNG_DRBG)			+= lrng_drng_drbg.o
+obj-$(CONFIG_LRNG_DRNG_KCAPI)		+= lrng_drng_kcapi.o
+obj-$(CONFIG_LRNG_DRNG_ATOMIC)		+= lrng_drng_atomic.o
+
+obj-$(CONFIG_LRNG_TIMER_COMMON)		+= lrng_es_timer_common.o
+obj-$(CONFIG_LRNG_IRQ)			+= lrng_es_irq.o
+obj-$(CONFIG_LRNG_KERNEL_RNG)		+= lrng_es_krng.o
+obj-$(CONFIG_LRNG_SCHED)		+= lrng_es_sched.o
+obj-$(CONFIG_LRNG_CPU)			+= lrng_es_cpu.o
+obj-$(CONFIG_LRNG_JENT)			+= lrng_es_jent.o
+
+obj-$(CONFIG_LRNG_HEALTH_TESTS)		+= lrng_health.o
+obj-$(CONFIG_LRNG_TESTING)		+= lrng_testing.o
+obj-$(CONFIG_LRNG_SELFTEST)		+= lrng_selftest.o
+
+obj-$(CONFIG_LRNG_COMMON_DEV_IF)	+= lrng_interface_dev_common.o
+obj-$(CONFIG_LRNG_RANDOM_IF)		+= lrng_interface_random_user.o \
+					   lrng_interface_random_kernel.o \
+					   lrng_interface_aux.o
+obj-$(CONFIG_LRNG_KCAPI_IF)		+= lrng_interface_kcapi.o
+obj-$(CONFIG_LRNG_DEV_IF)		+= lrng_interface_dev.o
+obj-$(CONFIG_LRNG_HWRAND_IF)		+= lrng_interface_hwrand.o
diff --git a/drivers/char/lrng/lrng_definitions.h b/drivers/char/lrng/lrng_definitions.h
new file mode 100644
index 000000000..f6eb48e28
--- /dev/null
+++ b/drivers/char/lrng/lrng_definitions.h
@@ -0,0 +1,163 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022 - 2023, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_DEFINITIONS_H
+#define _LRNG_DEFINITIONS_H
+
+#include <crypto/sha1.h>
+#include <crypto/sha2.h>
+#include <linux/slab.h>
+
+/*************************** General LRNG parameter ***************************/
+
+/*
+ * Specific settings for different use cases
+ */
+#ifdef CONFIG_CRYPTO_FIPS
+# define LRNG_OVERSAMPLE_ES_BITS	64
+# define LRNG_SEED_BUFFER_INIT_ADD_BITS	128
+#else /* CONFIG_CRYPTO_FIPS */
+# define LRNG_OVERSAMPLE_ES_BITS	0
+# define LRNG_SEED_BUFFER_INIT_ADD_BITS	0
+#endif /* CONFIG_CRYPTO_FIPS */
+
+/* Security strength of LRNG -- this must match DRNG security strength */
+#define LRNG_DRNG_SECURITY_STRENGTH_BYTES 32
+#define LRNG_DRNG_SECURITY_STRENGTH_BITS (LRNG_DRNG_SECURITY_STRENGTH_BYTES * 8)
+#define LRNG_DRNG_INIT_SEED_SIZE_BITS \
+	(LRNG_DRNG_SECURITY_STRENGTH_BITS + LRNG_SEED_BUFFER_INIT_ADD_BITS)
+#define LRNG_DRNG_INIT_SEED_SIZE_BYTES (LRNG_DRNG_INIT_SEED_SIZE_BITS >> 3)
+
+/*
+ * SP800-90A defines a maximum request size of 1<<16 bytes. The given value is
+ * considered a safer margin.
+ *
+ * This value is allowed to be changed.
+ */
+#define LRNG_DRNG_MAX_REQSIZE		(1<<12)
+
+/*
+ * SP800-90A defines a maximum number of requests between reseeds of 2^48.
+ * The given value is considered a much safer margin, balancing requests for
+ * frequent reseeds with the need to conserve entropy. This value MUST NOT be
+ * larger than INT_MAX because it is used in an atomic_t.
+ *
+ * This value is allowed to be changed.
+ */
+#define LRNG_DRNG_RESEED_THRESH		(1<<20)
+
+/*
+ * Maximum DRNG generation operations without reseed having full entropy
+ * This value defines the absolute maximum value of DRNG generation operations
+ * without a reseed holding full entropy. LRNG_DRNG_RESEED_THRESH is the
+ * threshold when a new reseed is attempted. But it is possible that this fails
+ * to deliver full entropy. In this case the DRNG will continue to provide data
+ * even though it was not reseeded with full entropy. To avoid in the extreme
+ * case that no reseed is performed for too long, this threshold is enforced.
+ * If that absolute low value is reached, the LRNG is marked as not operational.
+ *
+ * This value is allowed to be changed.
+ */
+#define LRNG_DRNG_MAX_WITHOUT_RESEED	(1<<30)
+
+/*
+ * Min required seed entropy is 128 bits covering the minimum entropy
+ * requirement of SP800-131A and the German BSI's TR02102.
+ *
+ * This value is allowed to be changed.
+ */
+#define LRNG_FULL_SEED_ENTROPY_BITS	LRNG_DRNG_SECURITY_STRENGTH_BITS
+#define LRNG_MIN_SEED_ENTROPY_BITS	128
+#define LRNG_INIT_ENTROPY_BITS		32
+
+/* AIS20/31: NTG.1.4 minimum entropy rate for one entropy source*/
+#define LRNG_AIS2031_NPTRNG_MIN_ENTROPY	220
+
+/*
+ * Wakeup value
+ *
+ * This value is allowed to be changed but must not be larger than the
+ * digest size of the hash operation used update the aux_pool.
+ */
+#ifdef CONFIG_LRNG_SHA256
+# define LRNG_ATOMIC_DIGEST_SIZE	SHA256_DIGEST_SIZE
+#else
+# define LRNG_ATOMIC_DIGEST_SIZE	SHA1_DIGEST_SIZE
+#endif
+#define LRNG_WRITE_WAKEUP_ENTROPY	LRNG_ATOMIC_DIGEST_SIZE
+
+/*
+ * If the switching support is configured, we must provide support up to
+ * the largest digest size. Without switching support, we know it is only
+ * the built-in digest size.
+ */
+#ifdef CONFIG_LRNG_SWITCH
+# define LRNG_MAX_DIGESTSIZE		64
+#else
+# define LRNG_MAX_DIGESTSIZE		LRNG_ATOMIC_DIGEST_SIZE
+#endif
+
+/*
+ * Oversampling factor of timer-based events to obtain
+ * LRNG_DRNG_SECURITY_STRENGTH_BYTES. This factor is used when a
+ * high-resolution time stamp is not available. In this case, jiffies and
+ * register contents are used to fill the entropy pool. These noise sources
+ * are much less entropic than the high-resolution timer. The entropy content
+ * is the entropy content assumed with LRNG_[IRQ|SCHED]_ENTROPY_BITS divided by
+ * LRNG_ES_OVERSAMPLING_FACTOR.
+ *
+ * This value is allowed to be changed.
+ */
+#define LRNG_ES_OVERSAMPLING_FACTOR	10
+
+/* Alignmask that is intended to be identical to CRYPTO_MINALIGN */
+#define LRNG_KCAPI_ALIGN		ARCH_KMALLOC_MINALIGN
+
+/*
+ * This definition must provide a buffer that is equal to SHASH_DESC_ON_STACK
+ * as it will be casted into a struct shash_desc.
+ */
+#define LRNG_POOL_SIZE	(sizeof(struct shash_desc) + HASH_MAX_DESCSIZE)
+
+/*
+ * Identification of a permanent health falure.
+ *
+ * Allow the given number of back-to-back health failures until incuring a
+ * permanent health failure. The chosen value implies an alpha of 2^-60
+ * considering that the alpha of one health failure is 2^-30
+ */
+#define LRNG_PERMANENT_HEALTH_FAILURES	2
+
+/****************************** Helper code ***********************************/
+
+static inline u32 lrng_fast_noise_entropylevel(u32 ent_bits, u32 requested_bits)
+{
+	/* Obtain entropy statement */
+	ent_bits = ent_bits * requested_bits / LRNG_DRNG_SECURITY_STRENGTH_BITS;
+	/* Cap entropy to buffer size in bits */
+	ent_bits = min_t(u32, ent_bits, requested_bits);
+	return ent_bits;
+}
+
+/* Convert entropy in bits into nr. of events with the same entropy content. */
+static inline u32 lrng_entropy_to_data(u32 entropy_bits, u32 entropy_rate)
+{
+	return ((entropy_bits * entropy_rate) /
+		LRNG_DRNG_SECURITY_STRENGTH_BITS);
+}
+
+/* Convert number of events into entropy value. */
+static inline u32 lrng_data_to_entropy(u32 num, u32 entropy_rate)
+{
+	return ((num * LRNG_DRNG_SECURITY_STRENGTH_BITS) /
+		entropy_rate);
+}
+
+static inline u32 atomic_read_u32(atomic_t *v)
+{
+	return (u32)atomic_read(v);
+}
+
+#endif /* _LRNG_DEFINITIONS_H */
diff --git a/drivers/char/lrng/lrng_drng_atomic.c b/drivers/char/lrng/lrng_drng_atomic.c
new file mode 100644
index 000000000..290d346ea
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_atomic.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG DRNG for atomic contexts
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+
+#include "lrng_drng_atomic.h"
+#include "lrng_drng_chacha20.h"
+#include "lrng_es_aux.h"
+#include "lrng_es_mgr.h"
+#include "lrng_sha.h"
+
+static struct chacha20_state chacha20_atomic = {
+	LRNG_CC20_INIT_RFC7539(.block)
+};
+
+/*
+ * DRNG usable in atomic context. This DRNG will always use the ChaCha20
+ * DRNG. It will never benefit from a DRNG switch like the "regular" DRNG. If
+ * there was no DRNG switch, the atomic DRNG is identical to the "regular" DRNG.
+ *
+ * The reason for having this is due to the fact that DRNGs other than
+ * the ChaCha20 DRNG may sleep.
+ */
+static struct lrng_drng lrng_drng_atomic = {
+	LRNG_DRNG_STATE_INIT(lrng_drng_atomic,
+			     &chacha20_atomic, NULL,
+			     &lrng_cc20_drng_cb, &lrng_sha_hash_cb),
+	.spin_lock	= __SPIN_LOCK_UNLOCKED(lrng_drng_atomic.spin_lock)
+};
+
+struct lrng_drng *lrng_get_atomic(void)
+{
+	return &lrng_drng_atomic;
+}
+
+void lrng_drng_atomic_reset(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&lrng_drng_atomic.spin_lock, flags);
+	lrng_drng_reset(&lrng_drng_atomic);
+	spin_unlock_irqrestore(&lrng_drng_atomic.spin_lock, flags);
+}
+
+void lrng_drng_atomic_force_reseed(void)
+{
+	lrng_drng_atomic.force_reseed = lrng_drng_atomic.fully_seeded;
+}
+
+static bool lrng_drng_atomic_must_reseed(struct lrng_drng *drng)
+{
+	return (!drng->fully_seeded ||
+		atomic_read(&lrng_drng_atomic.requests) == 0 ||
+		drng->force_reseed ||
+		time_after(jiffies,
+			   drng->last_seeded + lrng_drng_reseed_max_time * HZ));
+}
+
+void lrng_drng_atomic_seed_drng(struct lrng_drng *regular_drng)
+{
+	u8 seedbuf[LRNG_DRNG_SECURITY_STRENGTH_BYTES]
+						__aligned(LRNG_KCAPI_ALIGN);
+	int ret;
+
+	if (!lrng_drng_atomic_must_reseed(&lrng_drng_atomic))
+		return;
+
+	/*
+	 * Reseed atomic DRNG another DRNG "regular" while this regular DRNG
+	 * is reseeded. Therefore, this code operates in non-atomic context and
+	 * thus can use the lrng_drng_get function to get random numbers from
+	 * the just freshly seeded DRNG.
+	 */
+	ret = lrng_drng_get(regular_drng, seedbuf, sizeof(seedbuf));
+
+	if (ret < 0) {
+		pr_warn("Error generating random numbers for atomic DRNG: %d\n",
+			ret);
+	} else {
+		unsigned long flags;
+
+		spin_lock_irqsave(&lrng_drng_atomic.spin_lock, flags);
+		lrng_drng_inject(&lrng_drng_atomic, seedbuf, ret,
+				 regular_drng->fully_seeded, "atomic");
+		spin_unlock_irqrestore(&lrng_drng_atomic.spin_lock, flags);
+	}
+	memzero_explicit(&seedbuf, sizeof(seedbuf));
+}
+
+static void lrng_drng_atomic_get(u8 *outbuf, u32 outbuflen)
+{
+	struct lrng_drng *drng = &lrng_drng_atomic;
+	unsigned long flags;
+
+	if (!outbuf || !outbuflen)
+		return;
+
+	outbuflen = min_t(size_t, outbuflen, INT_MAX);
+
+	while (outbuflen) {
+		u32 todo = min_t(u32, outbuflen, LRNG_DRNG_MAX_REQSIZE);
+		int ret;
+
+		atomic_dec(&drng->requests);
+
+		spin_lock_irqsave(&drng->spin_lock, flags);
+		ret = drng->drng_cb->drng_generate(drng->drng, outbuf, todo);
+		spin_unlock_irqrestore(&drng->spin_lock, flags);
+		if (ret <= 0) {
+			pr_warn("getting random data from DRNG failed (%d)\n",
+				ret);
+			return;
+		}
+		outbuflen -= ret;
+		outbuf += ret;
+	}
+}
+
+void lrng_get_random_bytes(void *buf, int nbytes)
+{
+	lrng_drng_atomic_get((u8 *)buf, (u32)nbytes);
+	lrng_debug_report_seedlevel("lrng_get_random_bytes");
+}
+EXPORT_SYMBOL(lrng_get_random_bytes);
diff --git a/drivers/char/lrng/lrng_drng_atomic.h b/drivers/char/lrng/lrng_drng_atomic.h
new file mode 100644
index 000000000..7ae10f20b
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_atomic.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_DRNG_ATOMIC_H
+#define _LRNG_DRNG_ATOMIC_H
+
+#include "lrng_drng_mgr.h"
+
+#ifdef CONFIG_LRNG_DRNG_ATOMIC
+void lrng_drng_atomic_reset(void);
+void lrng_drng_atomic_seed_drng(struct lrng_drng *drng);
+void lrng_drng_atomic_force_reseed(void);
+struct lrng_drng *lrng_get_atomic(void);
+#else /* CONFIG_LRNG_DRNG_ATOMIC */
+static inline void lrng_drng_atomic_reset(void) { }
+static inline void lrng_drng_atomic_seed_drng(struct lrng_drng *drng) { }
+static inline void lrng_drng_atomic_force_reseed(void) { }
+static inline struct lrng_drng *lrng_get_atomic(void) { return NULL; }
+#endif /* CONFIG_LRNG_DRNG_ATOMIC */
+
+#endif /* _LRNG_DRNG_ATOMIC_H */
diff --git a/drivers/char/lrng/lrng_drng_chacha20.c b/drivers/char/lrng/lrng_drng_chacha20.c
new file mode 100644
index 000000000..31be102e3
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_chacha20.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Backend for the LRNG providing the cryptographic primitives using
+ * ChaCha20 cipher implementations.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <crypto/chacha.h>
+#include <linux/lrng.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+
+#include "lrng_drng_chacha20.h"
+
+/******************************* ChaCha20 DRNG *******************************/
+
+#define CHACHA_BLOCK_WORDS	(CHACHA_BLOCK_SIZE / sizeof(u32))
+
+/*
+ * Update of the ChaCha20 state by either using an unused buffer part or by
+ * generating one ChaCha20 block which is half of the state of the ChaCha20.
+ * The block is XORed into the key part of the state. This shall ensure
+ * backtracking resistance as well as a proper mix of the ChaCha20 state once
+ * the key is injected.
+ */
+static void lrng_chacha20_update(struct chacha20_state *chacha20_state,
+				 __le32 *buf, u32 used_words)
+{
+	struct chacha20_block *chacha20 = &chacha20_state->block;
+	u32 i;
+	__le32 tmp[CHACHA_BLOCK_WORDS];
+
+	BUILD_BUG_ON(sizeof(struct chacha20_block) != CHACHA_BLOCK_SIZE);
+	BUILD_BUG_ON(CHACHA_BLOCK_SIZE != 2 * CHACHA_KEY_SIZE);
+
+	if (used_words > CHACHA_KEY_SIZE_WORDS) {
+		chacha20_block(&chacha20->constants[0], (u8 *)tmp);
+		for (i = 0; i < CHACHA_KEY_SIZE_WORDS; i++)
+			chacha20->key.u[i] ^= le32_to_cpu(tmp[i]);
+		memzero_explicit(tmp, sizeof(tmp));
+	} else {
+		for (i = 0; i < CHACHA_KEY_SIZE_WORDS; i++)
+			chacha20->key.u[i] ^= le32_to_cpu(buf[i + used_words]);
+	}
+
+	/* Deterministic increment of nonce as required in RFC 7539 chapter 4 */
+	chacha20->nonce[0]++;
+	if (chacha20->nonce[0] == 0) {
+		chacha20->nonce[1]++;
+		if (chacha20->nonce[1] == 0)
+			chacha20->nonce[2]++;
+	}
+
+	/* Leave counter untouched as it is start value is undefined in RFC */
+}
+
+/*
+ * Seed the ChaCha20 DRNG by injecting the input data into the key part of
+ * the ChaCha20 state. If the input data is longer than the ChaCha20 key size,
+ * perform a ChaCha20 operation after processing of key size input data.
+ * This operation shall spread out the entropy into the ChaCha20 state before
+ * new entropy is injected into the key part.
+ */
+static int lrng_cc20_drng_seed_helper(void *drng, const u8 *inbuf, u32 inbuflen)
+{
+	struct chacha20_state *chacha20_state = (struct chacha20_state *)drng;
+	struct chacha20_block *chacha20 = &chacha20_state->block;
+
+	while (inbuflen) {
+		u32 i, todo = min_t(u32, inbuflen, CHACHA_KEY_SIZE);
+
+		for (i = 0; i < todo; i++)
+			chacha20->key.b[i] ^= inbuf[i];
+
+		/* Break potential dependencies between the inbuf key blocks */
+		lrng_chacha20_update(chacha20_state, NULL,
+				     CHACHA_BLOCK_WORDS);
+		inbuf += todo;
+		inbuflen -= todo;
+	}
+
+	return 0;
+}
+
+/*
+ * Chacha20 DRNG generation of random numbers: the stream output of ChaCha20
+ * is the random number. After the completion of the generation of the
+ * stream, the entire ChaCha20 state is updated.
+ *
+ * Note, as the ChaCha20 implements a 32 bit counter, we must ensure
+ * that this function is only invoked for at most 2^32 - 1 ChaCha20 blocks
+ * before a reseed or an update happens. This is ensured by the variable
+ * outbuflen which is a 32 bit integer defining the number of bytes to be
+ * generated by the ChaCha20 DRNG. At the end of this function, an update
+ * operation is invoked which implies that the 32 bit counter will never be
+ * overflown in this implementation.
+ */
+static int lrng_cc20_drng_generate_helper(void *drng, u8 *outbuf, u32 outbuflen)
+{
+	struct chacha20_state *chacha20_state = (struct chacha20_state *)drng;
+	struct chacha20_block *chacha20 = &chacha20_state->block;
+	__le32 aligned_buf[CHACHA_BLOCK_WORDS];
+	u32 ret = outbuflen, used = CHACHA_BLOCK_WORDS;
+	int zeroize_buf = 0;
+
+	while (outbuflen >= CHACHA_BLOCK_SIZE) {
+		chacha20_block(&chacha20->constants[0], outbuf);
+		outbuf += CHACHA_BLOCK_SIZE;
+		outbuflen -= CHACHA_BLOCK_SIZE;
+	}
+
+	if (outbuflen) {
+		chacha20_block(&chacha20->constants[0], (u8 *)aligned_buf);
+		memcpy(outbuf, aligned_buf, outbuflen);
+		used = ((outbuflen + sizeof(aligned_buf[0]) - 1) /
+			sizeof(aligned_buf[0]));
+		zeroize_buf = 1;
+	}
+
+	lrng_chacha20_update(chacha20_state, aligned_buf, used);
+
+	if (zeroize_buf)
+		memzero_explicit(aligned_buf, sizeof(aligned_buf));
+
+	return ret;
+}
+
+/*
+ * Allocation of the DRNG state
+ */
+static void *lrng_cc20_drng_alloc(u32 sec_strength)
+{
+	struct chacha20_state *state = NULL;
+
+	if (sec_strength > CHACHA_KEY_SIZE) {
+		pr_err("Security strength of ChaCha20 DRNG (%u bits) lower than requested by LRNG (%u bits)\n",
+			CHACHA_KEY_SIZE * 8, sec_strength * 8);
+		return ERR_PTR(-EINVAL);
+	}
+	if (sec_strength < CHACHA_KEY_SIZE)
+		pr_warn("Security strength of ChaCha20 DRNG (%u bits) higher than requested by LRNG (%u bits)\n",
+			CHACHA_KEY_SIZE * 8, sec_strength * 8);
+
+	state = kmalloc(sizeof(struct chacha20_state), GFP_KERNEL);
+	if (!state)
+		return ERR_PTR(-ENOMEM);
+	pr_debug("memory for ChaCha20 core allocated\n");
+
+	lrng_cc20_init_rfc7539(&state->block);
+
+	return state;
+}
+
+static void lrng_cc20_drng_dealloc(void *drng)
+{
+	struct chacha20_state *chacha20_state = (struct chacha20_state *)drng;
+
+	pr_debug("ChaCha20 core zeroized and freed\n");
+	kfree_sensitive(chacha20_state);
+}
+
+static const char *lrng_cc20_drng_name(void)
+{
+	return "ChaCha20 DRNG";
+}
+
+const struct lrng_drng_cb lrng_cc20_drng_cb = {
+	.drng_name	= lrng_cc20_drng_name,
+	.drng_alloc	= lrng_cc20_drng_alloc,
+	.drng_dealloc	= lrng_cc20_drng_dealloc,
+	.drng_seed	= lrng_cc20_drng_seed_helper,
+	.drng_generate	= lrng_cc20_drng_generate_helper,
+};
+
+#if !defined(CONFIG_LRNG_DFLT_DRNG_CHACHA20) && \
+    !defined(CONFIG_LRNG_DRNG_ATOMIC)
+static int __init lrng_cc20_drng_init(void)
+{
+	return lrng_set_drng_cb(&lrng_cc20_drng_cb);
+}
+
+static void __exit lrng_cc20_drng_exit(void)
+{
+	lrng_set_drng_cb(NULL);
+}
+
+late_initcall(lrng_cc20_drng_init);
+module_exit(lrng_cc20_drng_exit);
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
+MODULE_DESCRIPTION("Entropy Source and DRNG Manager - ChaCha20-based DRNG backend");
+#endif /* CONFIG_LRNG_DFLT_DRNG_CHACHA20 */
diff --git a/drivers/char/lrng/lrng_drng_chacha20.h b/drivers/char/lrng/lrng_drng_chacha20.h
new file mode 100644
index 000000000..fee657128
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_chacha20.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * LRNG ChaCha20 definitions
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_CHACHA20_H
+#define _LRNG_CHACHA20_H
+
+#include <crypto/chacha.h>
+
+/* State according to RFC 7539 section 2.3 */
+struct chacha20_block {
+	u32 constants[4];
+	union {
+#define CHACHA_KEY_SIZE_WORDS (CHACHA_KEY_SIZE / sizeof(u32))
+		u32 u[CHACHA_KEY_SIZE_WORDS];
+		u8  b[CHACHA_KEY_SIZE];
+	} key;
+	u32 counter;
+	u32 nonce[3];
+};
+
+struct chacha20_state {
+	struct chacha20_block block;
+};
+
+static inline void lrng_cc20_init_rfc7539(struct chacha20_block *chacha20)
+{
+	chacha_init_consts(chacha20->constants);
+}
+
+#define LRNG_CC20_INIT_RFC7539(x) \
+	x.constants[0] = 0x61707865, \
+	x.constants[1] = 0x3320646e, \
+	x.constants[2] = 0x79622d32, \
+	x.constants[3] = 0x6b206574,
+
+extern const struct lrng_drng_cb lrng_cc20_drng_cb;
+
+#endif /* _LRNG_CHACHA20_H */
diff --git a/drivers/char/lrng/lrng_drng_drbg.c b/drivers/char/lrng/lrng_drng_drbg.c
new file mode 100644
index 000000000..1feec2c09
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_drbg.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Backend for the LRNG providing the cryptographic primitives using the
+ * kernel crypto API and its DRBG.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <crypto/drbg.h>
+#include <linux/lrng.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include "lrng_drng_drbg.h"
+
+/*
+ * Define a DRBG plus a hash / MAC used to extract data from the entropy pool.
+ * For LRNG_HASH_NAME you can use a hash or a MAC (HMAC or CMAC) of your choice
+ * (Note, you should use the suggested selections below -- using SHA-1 or MD5
+ * is not wise). The idea is that the used cipher primitive can be selected to
+ * be the same as used for the DRBG. I.e. the LRNG only uses one cipher
+ * primitive using the same cipher implementation with the options offered in
+ * the following. This means, if the CTR DRBG is selected and AES-NI is present,
+ * both the CTR DRBG and the selected cmac(aes) use AES-NI.
+ *
+ * The security strengths of the DRBGs are all 256 bits according to
+ * SP800-57 section 5.6.1.
+ *
+ * This definition is allowed to be changed.
+ */
+#ifdef CONFIG_CRYPTO_DRBG_CTR
+static unsigned int lrng_drbg_type = 0;
+#elif defined CONFIG_CRYPTO_DRBG_HMAC
+static unsigned int lrng_drbg_type = 1;
+#elif defined CONFIG_CRYPTO_DRBG_HASH
+static unsigned int lrng_drbg_type = 2;
+#else
+#error "Unknown DRBG in use"
+#endif
+
+/* The parameter must be r/o in sysfs as otherwise races appear. */
+module_param(lrng_drbg_type, uint, 0444);
+MODULE_PARM_DESC(lrng_drbg_type, "DRBG type used for LRNG (0->CTR_DRBG, 1->HMAC_DRBG, 2->Hash_DRBG)");
+
+struct lrng_drbg {
+	const char *hash_name;
+	const char *drbg_core;
+};
+
+static const struct lrng_drbg lrng_drbg_types[] = {
+	{	/* CTR_DRBG with AES-256 using derivation function */
+		.drbg_core = "drbg_nopr_ctr_aes256",
+	}, {	/* HMAC_DRBG with SHA-512 */
+		.drbg_core = "drbg_nopr_hmac_sha512",
+	}, {	/* Hash_DRBG with SHA-512 using derivation function */
+		.drbg_core = "drbg_nopr_sha512"
+	}
+};
+
+static int lrng_drbg_drng_seed_helper(void *drng, const u8 *inbuf, u32 inbuflen)
+{
+	struct drbg_state *drbg = (struct drbg_state *)drng;
+	LIST_HEAD(seedlist);
+	struct drbg_string data;
+	int ret;
+
+	drbg_string_fill(&data, inbuf, inbuflen);
+	list_add_tail(&data.list, &seedlist);
+	ret = drbg->d_ops->update(drbg, &seedlist, drbg->seeded);
+
+	if (ret >= 0)
+		drbg->seeded = true;
+
+	return ret;
+}
+
+static int lrng_drbg_drng_generate_helper(void *drng, u8 *outbuf, u32 outbuflen)
+{
+	struct drbg_state *drbg = (struct drbg_state *)drng;
+
+	return drbg->d_ops->generate(drbg, outbuf, outbuflen, NULL);
+}
+
+static void *lrng_drbg_drng_alloc(u32 sec_strength)
+{
+	struct drbg_state *drbg;
+	int coreref = -1;
+	bool pr = false;
+	int ret;
+
+	drbg_convert_tfm_core(lrng_drbg_types[lrng_drbg_type].drbg_core,
+			      &coreref, &pr);
+	if (coreref < 0)
+		return ERR_PTR(-EFAULT);
+
+	drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
+	if (!drbg)
+		return ERR_PTR(-ENOMEM);
+
+	drbg->core = &drbg_cores[coreref];
+	drbg->seeded = false;
+	ret = drbg_alloc_state(drbg);
+	if (ret)
+		goto err;
+
+	if (sec_strength > drbg_sec_strength(drbg->core->flags)) {
+		pr_err("Security strength of DRBG (%u bits) lower than requested by LRNG (%u bits)\n",
+			drbg_sec_strength(drbg->core->flags) * 8,
+			sec_strength * 8);
+		goto dealloc;
+	}
+
+	if (sec_strength < drbg_sec_strength(drbg->core->flags))
+		pr_warn("Security strength of DRBG (%u bits) higher than requested by LRNG (%u bits)\n",
+			drbg_sec_strength(drbg->core->flags) * 8,
+			sec_strength * 8);
+
+	pr_info("DRBG with %s core allocated\n", drbg->core->backend_cra_name);
+
+	return drbg;
+
+dealloc:
+	if (drbg->d_ops)
+		drbg->d_ops->crypto_fini(drbg);
+	drbg_dealloc_state(drbg);
+err:
+	kfree(drbg);
+	return ERR_PTR(-EINVAL);
+}
+
+static void lrng_drbg_drng_dealloc(void *drng)
+{
+	struct drbg_state *drbg = (struct drbg_state *)drng;
+
+	if (drbg && drbg->d_ops)
+		drbg->d_ops->crypto_fini(drbg);
+	drbg_dealloc_state(drbg);
+	kfree_sensitive(drbg);
+	pr_info("DRBG deallocated\n");
+}
+
+static const char *lrng_drbg_name(void)
+{
+	return lrng_drbg_types[lrng_drbg_type].drbg_core;
+}
+
+const struct lrng_drng_cb lrng_drbg_cb = {
+	.drng_name	= lrng_drbg_name,
+	.drng_alloc	= lrng_drbg_drng_alloc,
+	.drng_dealloc	= lrng_drbg_drng_dealloc,
+	.drng_seed	= lrng_drbg_drng_seed_helper,
+	.drng_generate	= lrng_drbg_drng_generate_helper,
+};
+
+#ifndef CONFIG_LRNG_DFLT_DRNG_DRBG
+static int __init lrng_drbg_init(void)
+{
+	if (lrng_drbg_type >= ARRAY_SIZE(lrng_drbg_types)) {
+		pr_err("lrng_drbg_type parameter too large (given %u - max: %lu)",
+		       lrng_drbg_type,
+		       (unsigned long)ARRAY_SIZE(lrng_drbg_types) - 1);
+		return -EAGAIN;
+	}
+	return lrng_set_drng_cb(&lrng_drbg_cb);
+}
+
+static void __exit lrng_drbg_exit(void)
+{
+	lrng_set_drng_cb(NULL);
+}
+
+late_initcall(lrng_drbg_init);
+module_exit(lrng_drbg_exit);
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
+MODULE_DESCRIPTION("Entropy Source and DRNG Manager - SP800-90A DRBG backend");
+#endif /* CONFIG_LRNG_DFLT_DRNG_DRBG */
diff --git a/drivers/char/lrng/lrng_drng_drbg.h b/drivers/char/lrng/lrng_drng_drbg.h
new file mode 100644
index 000000000..b3d556caf
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_drbg.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * LRNG SP800-90A definitions
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_DRBG_H
+#define _LRNG_DRBG_H
+
+extern const struct lrng_drng_cb lrng_drbg_cb;
+
+#endif /* _LRNG_DRBG_H */
diff --git a/drivers/char/lrng/lrng_drng_kcapi.c b/drivers/char/lrng/lrng_drng_kcapi.c
new file mode 100644
index 000000000..a204bcf52
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_kcapi.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Backend for the LRNG providing the cryptographic primitives using the
+ * kernel crypto API.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <crypto/hash.h>
+#include <crypto/rng.h>
+#include <linux/init.h>
+#include <linux/module.h>
+
+#include "lrng_drng_kcapi.h"
+
+static char *drng_name = NULL;
+module_param(drng_name, charp, 0444);
+MODULE_PARM_DESC(drng_name, "Kernel crypto API name of DRNG");
+
+static char *seed_hash = NULL;
+module_param(seed_hash, charp, 0444);
+MODULE_PARM_DESC(seed_hash,
+		 "Kernel crypto API name of hash with output size equal to seedsize of DRNG to bring seed string to the size required by the DRNG");
+
+struct lrng_drng_info {
+	struct crypto_rng *kcapi_rng;
+	struct crypto_shash *hash_tfm;
+};
+
+static int lrng_kcapi_drng_seed_helper(void *drng, const u8 *inbuf,
+				       u32 inbuflen)
+{
+	struct lrng_drng_info *lrng_drng_info = (struct lrng_drng_info *)drng;
+	struct crypto_rng *kcapi_rng = lrng_drng_info->kcapi_rng;
+	struct crypto_shash *hash_tfm = lrng_drng_info->hash_tfm;
+	SHASH_DESC_ON_STACK(shash, hash_tfm);
+	u32 digestsize;
+	u8 digest[HASH_MAX_DIGESTSIZE] __aligned(8);
+	int ret;
+
+	if (!hash_tfm)
+		return crypto_rng_reset(kcapi_rng, inbuf, inbuflen);
+
+	shash->tfm = hash_tfm;
+	digestsize = crypto_shash_digestsize(hash_tfm);
+
+	ret = crypto_shash_digest(shash, inbuf, inbuflen, digest);
+	shash_desc_zero(shash);
+	if (ret)
+		return ret;
+
+	ret = crypto_rng_reset(kcapi_rng, digest, digestsize);
+	if (ret)
+		return ret;
+
+	memzero_explicit(digest, digestsize);
+	return 0;
+}
+
+static int lrng_kcapi_drng_generate_helper(void *drng, u8 *outbuf,
+					   u32 outbuflen)
+{
+	struct lrng_drng_info *lrng_drng_info = (struct lrng_drng_info *)drng;
+	struct crypto_rng *kcapi_rng = lrng_drng_info->kcapi_rng;
+	int ret = crypto_rng_get_bytes(kcapi_rng, outbuf, outbuflen);
+
+	if (ret < 0)
+		return ret;
+
+	return outbuflen;
+}
+
+static void *lrng_kcapi_drng_alloc(u32 sec_strength)
+{
+	struct lrng_drng_info *lrng_drng_info;
+	struct crypto_rng *kcapi_rng;
+	u32 time = random_get_entropy();
+	int seedsize, rv;
+	void *ret =  ERR_PTR(-ENOMEM);
+
+	if (!drng_name) {
+		pr_err("DRNG name missing\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (!memcmp(drng_name, "stdrng", 6) ||
+	    !memcmp(drng_name, "lrng", 4) ||
+	    !memcmp(drng_name, "drbg", 4) ||
+	    !memcmp(drng_name, "jitterentropy_rng", 17)) {
+		pr_err("Refusing to load the requested random number generator\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	lrng_drng_info = kzalloc(sizeof(*lrng_drng_info), GFP_KERNEL);
+	if (!lrng_drng_info)
+		return ERR_PTR(-ENOMEM);
+
+	kcapi_rng = crypto_alloc_rng(drng_name, 0, 0);
+	if (IS_ERR(kcapi_rng)) {
+		pr_err("DRNG %s cannot be allocated\n", drng_name);
+		ret = ERR_CAST(kcapi_rng);
+		goto free;
+	}
+
+	lrng_drng_info->kcapi_rng = kcapi_rng;
+
+	seedsize = crypto_rng_seedsize(kcapi_rng);
+	if (seedsize) {
+		struct crypto_shash *hash_tfm;
+
+		if (!seed_hash) {
+			switch (seedsize) {
+			case 32:
+				seed_hash = "sha256";
+				break;
+			case 48:
+				seed_hash = "sha384";
+				break;
+			case 64:
+				seed_hash = "sha512";
+				break;
+			default:
+				pr_err("Seed size %d cannot be processed\n",
+				       seedsize);
+				goto dealloc;
+			}
+		}
+
+		hash_tfm = crypto_alloc_shash(seed_hash, 0, 0);
+		if (IS_ERR(hash_tfm)) {
+			ret = ERR_CAST(hash_tfm);
+			goto dealloc;
+		}
+
+		if (seedsize != crypto_shash_digestsize(hash_tfm)) {
+			pr_err("Seed hash output size not equal to DRNG seed size\n");
+			crypto_free_shash(hash_tfm);
+			ret = ERR_PTR(-EINVAL);
+			goto dealloc;
+		}
+
+		lrng_drng_info->hash_tfm = hash_tfm;
+
+		pr_info("Seed hash %s allocated\n", seed_hash);
+	}
+
+	rv = lrng_kcapi_drng_seed_helper(lrng_drng_info, (u8 *)(&time),
+					 sizeof(time));
+	if (rv) {
+		ret = ERR_PTR(rv);
+		goto dealloc;
+	}
+
+	pr_info("Kernel crypto API DRNG %s allocated\n", drng_name);
+
+	return lrng_drng_info;
+
+dealloc:
+	crypto_free_rng(kcapi_rng);
+free:
+	kfree(lrng_drng_info);
+	return ret;
+}
+
+static void lrng_kcapi_drng_dealloc(void *drng)
+{
+	struct lrng_drng_info *lrng_drng_info = (struct lrng_drng_info *)drng;
+	struct crypto_rng *kcapi_rng = lrng_drng_info->kcapi_rng;
+
+	crypto_free_rng(kcapi_rng);
+	if (lrng_drng_info->hash_tfm)
+		crypto_free_shash(lrng_drng_info->hash_tfm);
+	kfree(lrng_drng_info);
+	pr_info("DRNG %s deallocated\n", drng_name);
+}
+
+static const char *lrng_kcapi_drng_name(void)
+{
+	return drng_name;
+}
+
+const struct lrng_drng_cb lrng_kcapi_drng_cb = {
+	.drng_name	= lrng_kcapi_drng_name,
+	.drng_alloc	= lrng_kcapi_drng_alloc,
+	.drng_dealloc	= lrng_kcapi_drng_dealloc,
+	.drng_seed	= lrng_kcapi_drng_seed_helper,
+	.drng_generate	= lrng_kcapi_drng_generate_helper,
+};
+
+#ifndef CONFIG_LRNG_DFLT_DRNG_KCAPI
+static int __init lrng_kcapi_init(void)
+{
+	return lrng_set_drng_cb(&lrng_kcapi_drng_cb);
+}
+static void __exit lrng_kcapi_exit(void)
+{
+	lrng_set_drng_cb(NULL);
+}
+
+late_initcall(lrng_kcapi_init);
+module_exit(lrng_kcapi_exit);
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
+MODULE_DESCRIPTION("Entropy Source and DRNG Manager - kernel crypto API DRNG backend");
+#endif /* CONFIG_LRNG_DFLT_DRNG_KCAPI */
diff --git a/drivers/char/lrng/lrng_drng_kcapi.h b/drivers/char/lrng/lrng_drng_kcapi.h
new file mode 100644
index 000000000..5db25aaf8
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_kcapi.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * LRNG kernel crypto API DRNG definition
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_KCAPI_DRNG_H
+#define _LRNG_KCAPI_DRNG_H
+
+extern const struct lrng_drng_cb lrng_kcapi_drng_cb;
+
+#endif /* _LRNG_KCAPI_DRNG_H */
diff --git a/drivers/char/lrng/lrng_drng_mgr.c b/drivers/char/lrng/lrng_drng_mgr.c
new file mode 100644
index 000000000..3d9ed60a7
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_mgr.c
@@ -0,0 +1,742 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG DRNG management
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <linux/fips.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+
+#include "lrng_drng_atomic.h"
+#include "lrng_drng_chacha20.h"
+#include "lrng_drng_drbg.h"
+#include "lrng_drng_kcapi.h"
+#include "lrng_drng_mgr.h"
+#include "lrng_es_aux.h"
+#include "lrng_es_mgr.h"
+#include "lrng_interface_random_kernel.h"
+#include "lrng_numa.h"
+#include "lrng_sha.h"
+
+/*
+ * Maximum number of seconds between DRNG reseed intervals of the DRNG. Note,
+ * this is enforced with the next request of random numbers from the
+ * DRNG. Setting this value to zero implies a reseeding attempt before every
+ * generated random number.
+ */
+int lrng_drng_reseed_max_time = 600;
+
+/*
+ * Is LRNG for general-purpose use (i.e. is at least the lrng_drng_init
+ * fully allocated)?
+ */
+static atomic_t lrng_avail = ATOMIC_INIT(0);
+
+/* Guard protecting all crypto callback update operation of all DRNGs. */
+DEFINE_MUTEX(lrng_crypto_cb_update);
+
+/*
+ * Default hash callback that provides the crypto primitive right from the
+ * kernel start. It must not perform any memory allocation operation, but
+ * simply perform the hash calculation.
+ */
+const struct lrng_hash_cb *lrng_default_hash_cb = &lrng_sha_hash_cb;
+
+/*
+ * Default DRNG callback that provides the crypto primitive which is
+ * allocated either during late kernel boot stage. So, it is permissible for
+ * the callback to perform memory allocation operations.
+ */
+const struct lrng_drng_cb *lrng_default_drng_cb =
+#if defined(CONFIG_LRNG_DFLT_DRNG_CHACHA20)
+	&lrng_cc20_drng_cb;
+#elif defined(CONFIG_LRNG_DFLT_DRNG_DRBG)
+	&lrng_drbg_cb;
+#elif defined(CONFIG_LRNG_DFLT_DRNG_KCAPI)
+	&lrng_kcapi_drng_cb;
+#else
+#error "Unknown default DRNG selected"
+#endif
+
+/* DRNG for non-atomic use cases */
+static struct lrng_drng lrng_drng_init = {
+	LRNG_DRNG_STATE_INIT(lrng_drng_init, NULL, NULL, NULL,
+			     &lrng_sha_hash_cb),
+	.lock = __MUTEX_INITIALIZER(lrng_drng_init.lock),
+};
+
+/* Prediction-resistance DRNG: only deliver as much data as received entropy */
+static struct lrng_drng lrng_drng_pr = {
+	LRNG_DRNG_STATE_INIT(lrng_drng_pr, NULL, NULL, NULL,
+			     &lrng_sha_hash_cb),
+	.lock = __MUTEX_INITIALIZER(lrng_drng_pr.lock),
+};
+
+static u32 max_wo_reseed = LRNG_DRNG_MAX_WITHOUT_RESEED;
+#ifdef CONFIG_LRNG_RUNTIME_MAX_WO_RESEED_CONFIG
+module_param(max_wo_reseed, uint, 0444);
+MODULE_PARM_DESC(max_wo_reseed,
+		 "Maximum number of DRNG generate operation without full reseed\n");
+#endif
+
+static bool force_seeding = true;
+#ifdef CONFIG_LRNG_RUNTIME_FORCE_SEEDING_DISABLE
+module_param(force_seeding, bool, 0444);
+MODULE_PARM_DESC(force_seeding,
+		 "Allow disabling of the forced seeding when insufficient entropy is availabe\n");
+#endif
+
+/* Wait queue to wait until the LRNG is initialized - can freely be used */
+DECLARE_WAIT_QUEUE_HEAD(lrng_init_wait);
+
+/********************************** Helper ************************************/
+
+bool lrng_get_available(void)
+{
+	return likely(atomic_read(&lrng_avail));
+}
+
+struct lrng_drng *lrng_drng_init_instance(void)
+{
+	return &lrng_drng_init;
+}
+
+struct lrng_drng *lrng_drng_pr_instance(void)
+{
+	return &lrng_drng_pr;
+}
+
+struct lrng_drng *lrng_drng_node_instance(void)
+{
+	struct lrng_drng **lrng_drng = lrng_drng_instances();
+	int node = numa_node_id();
+
+	if (lrng_drng && lrng_drng[node])
+		return lrng_drng[node];
+
+	return lrng_drng_init_instance();
+}
+
+void lrng_drng_reset(struct lrng_drng *drng)
+{
+	/* Ensure reseed during next call */
+	atomic_set(&drng->requests, 1);
+	atomic_set(&drng->requests_since_fully_seeded, 0);
+	drng->last_seeded = jiffies;
+	drng->fully_seeded = false;
+	/* Do not set force, as this flag is used for the emergency reseeding */
+	drng->force_reseed = false;
+	pr_debug("reset DRNG\n");
+}
+
+/* Initialize the DRNG, except the mutex lock */
+int lrng_drng_alloc_common(struct lrng_drng *drng,
+			   const struct lrng_drng_cb *drng_cb)
+{
+	if (!drng || !drng_cb)
+		return -EINVAL;
+	if (!IS_ERR_OR_NULL(drng->drng))
+		return 0;
+
+	drng->drng_cb = drng_cb;
+	drng->drng = drng_cb->drng_alloc(LRNG_DRNG_SECURITY_STRENGTH_BYTES);
+	if (IS_ERR(drng->drng))
+		return -PTR_ERR(drng->drng);
+
+	lrng_drng_reset(drng);
+	return 0;
+}
+
+/* Initialize the default DRNG during boot and perform its seeding */
+int lrng_drng_initalize(void)
+{
+	int ret;
+
+	if (lrng_get_available())
+		return 0;
+
+	/* Catch programming error */
+	WARN_ON(lrng_drng_init.hash_cb != lrng_default_hash_cb);
+
+	mutex_lock(&lrng_drng_init.lock);
+	if (lrng_get_available()) {
+		mutex_unlock(&lrng_drng_init.lock);
+		return 0;
+	}
+
+	/* Initialize the PR DRNG inside init lock as it guards lrng_avail. */
+	mutex_lock(&lrng_drng_pr.lock);
+	ret = lrng_drng_alloc_common(&lrng_drng_pr, lrng_default_drng_cb);
+	mutex_unlock(&lrng_drng_pr.lock);
+
+	if (!ret) {
+		ret = lrng_drng_alloc_common(&lrng_drng_init,
+					     lrng_default_drng_cb);
+		if (!ret)
+			atomic_set(&lrng_avail, 1);
+	}
+	mutex_unlock(&lrng_drng_init.lock);
+	if (ret)
+		return ret;
+
+	pr_debug("LRNG for general use is available\n");
+
+	/* Seed the DRNG with any entropy available */
+	if (lrng_pool_trylock()) {
+		pr_info("Initial DRNG initialized triggering first seeding\n");
+		lrng_drng_seed_work(NULL);
+	} else {
+		pr_info("Initial DRNG initialized without seeding\n");
+	}
+
+	return 0;
+}
+
+static int __init lrng_drng_make_available(void)
+{
+	return lrng_drng_initalize();
+}
+late_initcall(lrng_drng_make_available);
+
+bool lrng_sp80090c_compliant(void)
+{
+	/* SP800-90C compliant oversampling is only requested in FIPS mode */
+	return fips_enabled;
+}
+
+/************************* Random Number Generation ***************************/
+
+/* Inject a data buffer into the DRNG - caller must hold its lock */
+void lrng_drng_inject(struct lrng_drng *drng, const u8 *inbuf, u32 inbuflen,
+		      bool fully_seeded, const char *drng_type)
+{
+	BUILD_BUG_ON(LRNG_DRNG_RESEED_THRESH > INT_MAX);
+	pr_debug("seeding %s DRNG with %u bytes\n", drng_type, inbuflen);
+	if (drng->drng_cb->drng_seed(drng->drng, inbuf, inbuflen) < 0) {
+		pr_warn("seeding of %s DRNG failed\n", drng_type);
+		drng->force_reseed = true;
+	} else {
+		int gc = LRNG_DRNG_RESEED_THRESH - atomic_read(&drng->requests);
+
+		pr_debug("%s DRNG stats since last seeding: %lu secs; generate calls: %d\n",
+			 drng_type,
+			 (time_after(jiffies, drng->last_seeded) ?
+			  (jiffies - drng->last_seeded) : 0) / HZ, gc);
+
+		/* Count the numbers of generate ops since last fully seeded */
+		if (fully_seeded)
+			atomic_set(&drng->requests_since_fully_seeded, 0);
+		else
+			atomic_add(gc, &drng->requests_since_fully_seeded);
+
+		drng->last_seeded = jiffies;
+		atomic_set(&drng->requests, LRNG_DRNG_RESEED_THRESH);
+		drng->force_reseed = false;
+
+		if (!drng->fully_seeded) {
+			drng->fully_seeded = fully_seeded;
+			if (drng->fully_seeded)
+				pr_debug("%s DRNG fully seeded\n", drng_type);
+		}
+	}
+}
+
+/*
+ * Perform the seeding of the DRNG with data from entropy source.
+ * The function returns the entropy injected into the DRNG in bits.
+ */
+static u32 lrng_drng_seed_es_nolock(struct lrng_drng *drng, bool init_ops,
+				    const char *drng_type)
+{
+	struct entropy_buf seedbuf __aligned(LRNG_KCAPI_ALIGN),
+			   collected_seedbuf;
+	u32 collected_entropy = 0;
+	unsigned int i, num_es_delivered = 0;
+	bool forced = drng->force_reseed;
+
+	for_each_lrng_es(i)
+		collected_seedbuf.e_bits[i] = 0;
+
+	do {
+		/* Count the number of ES which delivered entropy */
+		num_es_delivered = 0;
+
+		if (collected_entropy)
+			pr_debug("Force fully seeding level for %s DRNG by repeatedly pull entropy from available entropy sources\n",
+				 drng_type);
+
+		lrng_fill_seed_buffer(&seedbuf,
+			lrng_get_seed_entropy_osr(drng->fully_seeded),
+				      forced && !drng->fully_seeded);
+
+		collected_entropy += lrng_entropy_rate_eb(&seedbuf);
+
+		/* Sum iterations up. */
+		for_each_lrng_es(i) {
+			collected_seedbuf.e_bits[i] += seedbuf.e_bits[i];
+			num_es_delivered += !!seedbuf.e_bits[i];
+		}
+
+		lrng_drng_inject(drng, (u8 *)&seedbuf, sizeof(seedbuf),
+				 lrng_fully_seeded(drng->fully_seeded,
+						   collected_entropy,
+						   &collected_seedbuf),
+				 drng_type);
+
+		/*
+		 * Set the seeding state of the LRNG
+		 *
+		 * Do not call lrng_init_ops(seedbuf) here as the atomic DRNG
+		 * does not serve common users.
+		 */
+		if (init_ops)
+			lrng_init_ops(&collected_seedbuf);
+
+	/*
+	 * Emergency reseeding: If we reached the min seed threshold now
+	 * multiple times but never reached fully seeded level and we collect
+	 * entropy, keep doing it until we reached fully seeded level for
+	 * at least one DRNG. This operation is not continued if the
+	 * ES do not deliver entropy such that we cannot reach the fully seeded
+	 * level.
+	 *
+	 * The emergency reseeding implies that the consecutively injected
+	 * entropy can be added up. This is applicable due to the fact that
+	 * the entire operation is atomic which means that the DRNG is not
+	 * producing data while this is ongoing.
+	 */
+	} while (force_seeding && forced && !drng->fully_seeded &&
+		 num_es_delivered >= (lrng_ntg1_2022_compliant() ? 2 : 1));
+
+	memzero_explicit(&seedbuf, sizeof(seedbuf));
+
+	return collected_entropy;
+}
+
+static void lrng_drng_seed_es(struct lrng_drng *drng)
+{
+	mutex_lock(&drng->lock);
+	lrng_drng_seed_es_nolock(drng, true, "regular");
+	mutex_unlock(&drng->lock);
+}
+
+static void lrng_drng_seed(struct lrng_drng *drng)
+{
+	BUILD_BUG_ON(LRNG_MIN_SEED_ENTROPY_BITS >
+		     LRNG_DRNG_SECURITY_STRENGTH_BITS);
+
+	/* (Re-)Seed DRNG */
+	lrng_drng_seed_es(drng);
+	/* (Re-)Seed atomic DRNG from regular DRNG */
+	lrng_drng_atomic_seed_drng(drng);
+}
+
+static void lrng_drng_seed_work_one(struct lrng_drng *drng, u32 node)
+{
+	pr_debug("reseed triggered by system events for DRNG on NUMA node %d\n",
+		 node);
+	lrng_drng_seed(drng);
+	if (drng->fully_seeded) {
+		/* Prevent reseed storm */
+		drng->last_seeded += node * 100 * HZ;
+	}
+}
+
+/*
+ * DRNG reseed trigger: Kernel thread handler triggered by the schedule_work()
+ */
+static void __lrng_drng_seed_work(bool force)
+{
+	struct lrng_drng **lrng_drng;
+	u32 node;
+
+	/*
+	 * If the DRNG is not yet initialized, let us try to seed the atomic
+	 * DRNG.
+	 */
+	if (!lrng_get_available()) {
+		struct lrng_drng *atomic;
+		unsigned long flags;
+
+		if (wq_has_sleeper(&lrng_init_wait)) {
+			lrng_init_ops(NULL);
+			return;
+		}
+		atomic = lrng_get_atomic();
+		if (!atomic || atomic->fully_seeded)
+			return;
+
+		atomic->force_reseed |= force;
+		spin_lock_irqsave(&atomic->spin_lock, flags);
+		lrng_drng_seed_es_nolock(atomic, false, "atomic");
+		spin_unlock_irqrestore(&atomic->spin_lock, flags);
+
+		return;
+	}
+
+	lrng_drng = lrng_drng_instances();
+	if (lrng_drng) {
+		for_each_online_node(node) {
+			struct lrng_drng *drng = lrng_drng[node];
+
+			if (drng && !drng->fully_seeded) {
+				drng->force_reseed |= force;
+				lrng_drng_seed_work_one(drng, node);
+				return;
+			}
+		}
+	} else {
+		if (!lrng_drng_init.fully_seeded) {
+			lrng_drng_init.force_reseed |= force;
+			lrng_drng_seed_work_one(&lrng_drng_init, 0);
+			return;
+		}
+	}
+
+	if (!lrng_drng_pr.fully_seeded) {
+		lrng_drng_pr.force_reseed |= force;
+		lrng_drng_seed_work_one(&lrng_drng_pr, 0);
+		return;
+	}
+
+	lrng_pool_all_numa_nodes_seeded(true);
+}
+
+void lrng_drng_seed_work(struct work_struct *dummy)
+{
+	__lrng_drng_seed_work(false);
+
+	/* Allow the seeding operation to be called again */
+	lrng_pool_unlock();
+}
+
+/* Force all DRNGs to reseed before next generation */
+void lrng_drng_force_reseed(void)
+{
+	struct lrng_drng **lrng_drng = lrng_drng_instances();
+	u32 node;
+
+	/*
+	 * If the initial DRNG is over the reseed threshold, allow a forced
+	 * reseed only for the initial DRNG as this is the fallback for all. It
+	 * must be kept seeded before all others to keep the LRNG operational.
+	 */
+	if (!lrng_drng ||
+	    (atomic_read_u32(&lrng_drng_init.requests_since_fully_seeded) >
+	     LRNG_DRNG_RESEED_THRESH)) {
+		lrng_drng_init.force_reseed = lrng_drng_init.fully_seeded;
+		pr_debug("force reseed of initial DRNG\n");
+		return;
+	}
+	for_each_online_node(node) {
+		struct lrng_drng *drng = lrng_drng[node];
+
+		if (!drng)
+			continue;
+
+		drng->force_reseed = drng->fully_seeded;
+		pr_debug("force reseed of DRNG on node %u\n", node);
+	}
+	lrng_drng_atomic_force_reseed();
+}
+EXPORT_SYMBOL(lrng_drng_force_reseed);
+
+static bool lrng_drng_must_reseed(struct lrng_drng *drng)
+{
+	return (atomic_dec_and_test(&drng->requests) ||
+		drng->force_reseed ||
+		time_after(jiffies,
+			   drng->last_seeded + lrng_drng_reseed_max_time * HZ));
+}
+
+/*
+ * lrng_drng_get() - Get random data out of the DRNG which is reseeded
+ * frequently.
+ *
+ * @drng: DRNG instance
+ * @outbuf: buffer for storing random data
+ * @outbuflen: length of outbuf
+ *
+ * Return:
+ * * < 0 in error case (DRNG generation or update failed)
+ * * >=0 returning the returned number of bytes
+ */
+int lrng_drng_get(struct lrng_drng *drng, u8 *outbuf, u32 outbuflen)
+{
+	u32 processed = 0;
+	bool pr = (drng == &lrng_drng_pr) ? true : false;
+
+	if (!outbuf || !outbuflen)
+		return 0;
+
+	if (!lrng_get_available())
+		return -EOPNOTSUPP;
+
+	outbuflen = min_t(size_t, outbuflen, INT_MAX);
+
+	/* If DRNG operated without proper reseed for too long, block LRNG */
+	BUILD_BUG_ON(LRNG_DRNG_MAX_WITHOUT_RESEED < LRNG_DRNG_RESEED_THRESH);
+	if (atomic_read_u32(&drng->requests_since_fully_seeded) > max_wo_reseed)
+		lrng_unset_fully_seeded(drng);
+
+	while (outbuflen) {
+		u32 todo = min_t(u32, outbuflen, LRNG_DRNG_MAX_REQSIZE);
+		int ret;
+
+		/* In normal operation, check whether to reseed */
+		if (!pr && lrng_drng_must_reseed(drng)) {
+			if (!lrng_pool_trylock()) {
+				drng->force_reseed = true;
+			} else {
+				lrng_drng_seed(drng);
+				lrng_pool_unlock();
+			}
+		}
+
+		mutex_lock(&drng->lock);
+
+		if (pr) {
+			/* If async reseed did not deliver entropy, try now */
+			if (!drng->fully_seeded) {
+				u32 coll_ent_bits;
+
+				/* If we cannot get the pool lock, try again. */
+				if (!lrng_pool_trylock()) {
+					mutex_unlock(&drng->lock);
+					continue;
+				}
+
+				coll_ent_bits = lrng_drng_seed_es_nolock(
+							drng, true, "regular");
+
+				lrng_pool_unlock();
+
+				/* If no new entropy was received, stop now. */
+				if (!coll_ent_bits) {
+					mutex_unlock(&drng->lock);
+					goto out;
+				}
+
+				/* Produce no more data than received entropy */
+				todo = min_t(u32, todo, coll_ent_bits >> 3);
+			}
+
+			/* Do not produce more than DRNG security strength */
+			todo = min_t(u32, todo, lrng_security_strength() >> 3);
+		}
+		ret = drng->drng_cb->drng_generate(drng->drng,
+						   outbuf + processed, todo);
+
+		mutex_unlock(&drng->lock);
+		if (ret <= 0) {
+			pr_warn("getting random data from DRNG failed (%d)\n",
+				ret);
+			return -EFAULT;
+		}
+		processed += ret;
+		outbuflen -= ret;
+
+		if (pr) {
+			/* Force the async reseed for PR DRNG */
+			lrng_unset_fully_seeded(drng);
+			if (outbuflen)
+				cond_resched();
+		}
+	}
+
+out:
+	return processed;
+}
+
+int lrng_drng_get_sleep(u8 *outbuf, u32 outbuflen, bool pr)
+{
+	struct lrng_drng **lrng_drng = lrng_drng_instances();
+	struct lrng_drng *drng = &lrng_drng_init;
+	int ret, node = numa_node_id();
+
+	might_sleep();
+
+	if (pr)
+		drng = &lrng_drng_pr;
+	else if (lrng_drng && lrng_drng[node] && lrng_drng[node]->fully_seeded)
+		drng = lrng_drng[node];
+
+	ret = lrng_drng_initalize();
+	if (ret)
+		return ret;
+
+	return lrng_drng_get(drng, outbuf, outbuflen);
+}
+
+/* Reset LRNG such that all existing entropy is gone */
+static void _lrng_reset(struct work_struct *work)
+{
+	struct lrng_drng **lrng_drng = lrng_drng_instances();
+
+	if (!lrng_drng) {
+		mutex_lock(&lrng_drng_init.lock);
+		lrng_drng_reset(&lrng_drng_init);
+		mutex_unlock(&lrng_drng_init.lock);
+	} else {
+		u32 node;
+
+		for_each_online_node(node) {
+			struct lrng_drng *drng = lrng_drng[node];
+
+			if (!drng)
+				continue;
+			mutex_lock(&drng->lock);
+			lrng_drng_reset(drng);
+			mutex_unlock(&drng->lock);
+		}
+	}
+
+	mutex_lock(&lrng_drng_pr.lock);
+	lrng_drng_reset(&lrng_drng_pr);
+	mutex_unlock(&lrng_drng_pr.lock);
+
+	lrng_drng_atomic_reset();
+	lrng_set_entropy_thresh(LRNG_INIT_ENTROPY_BITS);
+
+	lrng_reset_state();
+}
+
+static DECLARE_WORK(lrng_reset_work, _lrng_reset);
+
+void lrng_reset(void)
+{
+	schedule_work(&lrng_reset_work);
+}
+
+/******************* Generic LRNG kernel output interfaces ********************/
+
+void lrng_force_fully_seeded(void)
+{
+	if (lrng_pool_all_numa_nodes_seeded_get())
+		return;
+
+	lrng_pool_lock();
+	__lrng_drng_seed_work(true);
+	lrng_pool_unlock();
+}
+
+static int lrng_drng_sleep_while_not_all_nodes_seeded(unsigned int nonblock)
+{
+	lrng_force_fully_seeded();
+	if (lrng_pool_all_numa_nodes_seeded_get())
+		return 0;
+	if (nonblock)
+		return -EAGAIN;
+	wait_event_interruptible(lrng_init_wait,
+				 lrng_pool_all_numa_nodes_seeded_get());
+	return 0;
+}
+
+int lrng_drng_sleep_while_nonoperational(int nonblock)
+{
+	lrng_force_fully_seeded();
+	if (likely(lrng_state_operational()))
+		return 0;
+	if (nonblock)
+		return -EAGAIN;
+	return wait_event_interruptible(lrng_init_wait,
+					lrng_state_operational());
+}
+
+int lrng_drng_sleep_while_non_min_seeded(void)
+{
+	lrng_force_fully_seeded();
+	if (likely(lrng_state_min_seeded()))
+		return 0;
+	return wait_event_interruptible(lrng_init_wait,
+					lrng_state_min_seeded());
+}
+
+ssize_t lrng_get_seed(u64 *buf, size_t nbytes, unsigned int flags)
+{
+	struct entropy_buf *eb = (struct entropy_buf *)(buf + 2);
+	u64 buflen = sizeof(struct entropy_buf) + 2 * sizeof(u64);
+	u64 collected_bits = 0;
+	int ret;
+
+	/* Ensure buffer is aligned as required */
+	BUILD_BUG_ON(sizeof(buflen) > LRNG_KCAPI_ALIGN);
+	if (nbytes < sizeof(buflen))
+		return -EINVAL;
+
+	/* Write buffer size into first word */
+	buf[0] = buflen;
+	if (nbytes < buflen)
+		return -EMSGSIZE;
+
+	ret = lrng_drng_sleep_while_not_all_nodes_seeded(
+		flags & LRNG_GET_SEED_NONBLOCK);
+	if (ret)
+		return ret;
+
+	/* Try to get the pool lock and sleep on it to get it. */
+	lrng_pool_lock();
+
+	/* If an LRNG DRNG becomes unseeded, give this DRNG precedence. */
+	if (!lrng_pool_all_numa_nodes_seeded_get()) {
+		lrng_pool_unlock();
+		return 0;
+	}
+
+	/*
+	 * Try to get seed data - a rarely used busyloop is cheaper than a wait
+	 * queue that is constantly woken up by the hot code path of
+	 * lrng_init_ops.
+	 */
+	for (;;) {
+		lrng_fill_seed_buffer(eb,
+			lrng_get_seed_entropy_osr(flags &
+						  LRNG_GET_SEED_FULLY_SEEDED),
+						  false);
+		collected_bits = lrng_entropy_rate_eb(eb);
+
+		/* Break the collection loop if we got entropy, ... */
+		if (collected_bits ||
+		    /* ... a DRNG becomes unseeded, give DRNG precedence, ... */
+		    !lrng_pool_all_numa_nodes_seeded_get() ||
+		    /* ... if the caller does not want a blocking behavior. */
+		    (flags & LRNG_GET_SEED_NONBLOCK))
+			break;
+
+		schedule();
+	}
+
+	lrng_pool_unlock();
+
+	/* Write collected entropy size into second word */
+	buf[1] = collected_bits;
+
+	return (ssize_t)buflen;
+}
+
+void lrng_get_random_bytes_full(void *buf, int nbytes)
+{
+	lrng_drng_sleep_while_nonoperational(0);
+	lrng_drng_get_sleep((u8 *)buf, (u32)nbytes, false);
+}
+EXPORT_SYMBOL(lrng_get_random_bytes_full);
+
+void lrng_get_random_bytes_min(void *buf, int nbytes)
+{
+	lrng_drng_sleep_while_non_min_seeded();
+	lrng_drng_get_sleep((u8 *)buf, (u32)nbytes, false);
+}
+EXPORT_SYMBOL(lrng_get_random_bytes_min);
+
+int lrng_get_random_bytes_pr(void *buf, int nbytes)
+{
+	lrng_drng_sleep_while_nonoperational(0);
+	return lrng_drng_get_sleep((u8 *)buf, (u32)nbytes, true);
+}
+EXPORT_SYMBOL(lrng_get_random_bytes_pr);
diff --git a/drivers/char/lrng/lrng_drng_mgr.h b/drivers/char/lrng/lrng_drng_mgr.h
new file mode 100644
index 000000000..8b1de3827
--- /dev/null
+++ b/drivers/char/lrng/lrng_drng_mgr.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_DRNG_H
+#define _LRNG_DRNG_H
+
+#include <linux/mutex.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+
+#include "lrng_definitions.h"
+
+extern struct wait_queue_head lrng_init_wait;
+extern int lrng_drng_reseed_max_time;
+extern struct mutex lrng_crypto_cb_update;
+extern const struct lrng_drng_cb *lrng_default_drng_cb;
+extern const struct lrng_hash_cb *lrng_default_hash_cb;
+
+/* DRNG state handle */
+struct lrng_drng {
+	void *drng;				/* DRNG handle */
+	void *hash;				/* Hash handle */
+	const struct lrng_drng_cb *drng_cb;	/* DRNG callbacks */
+	const struct lrng_hash_cb *hash_cb;	/* Hash callbacks */
+	atomic_t requests;			/* Number of DRNG requests */
+	atomic_t requests_since_fully_seeded;	/* Number DRNG requests since
+						 * last fully seeded
+						 */
+	unsigned long last_seeded;		/* Last time it was seeded */
+	bool fully_seeded;			/* Is DRNG fully seeded? */
+	bool force_reseed;			/* Force a reseed */
+
+	rwlock_t hash_lock;			/* Lock hash_cb replacement */
+	/* Lock write operations on DRNG state, DRNG replacement of drng_cb */
+	struct mutex lock;			/* Non-atomic DRNG operation */
+	spinlock_t spin_lock;			/* Atomic DRNG operation */
+};
+
+#define LRNG_DRNG_STATE_INIT(x, d, h, d_cb, h_cb) \
+	.drng				= d, \
+	.hash				= h, \
+	.drng_cb			= d_cb, \
+	.hash_cb			= h_cb, \
+	.requests			= ATOMIC_INIT(LRNG_DRNG_RESEED_THRESH),\
+	.requests_since_fully_seeded	= ATOMIC_INIT(0), \
+	.last_seeded			= 0, \
+	.fully_seeded			= false, \
+	.force_reseed			= true, \
+	.hash_lock			= __RW_LOCK_UNLOCKED(x.hash_lock)
+
+struct lrng_drng *lrng_drng_init_instance(void);
+struct lrng_drng *lrng_drng_pr_instance(void);
+struct lrng_drng *lrng_drng_node_instance(void);
+
+void lrng_reset(void);
+int lrng_drng_alloc_common(struct lrng_drng *drng,
+			   const struct lrng_drng_cb *crypto_cb);
+int lrng_drng_initalize(void);
+bool lrng_sp80090c_compliant(void);
+bool lrng_get_available(void);
+void lrng_drng_reset(struct lrng_drng *drng);
+void lrng_drng_inject(struct lrng_drng *drng, const u8 *inbuf, u32 inbuflen,
+		      bool fully_seeded, const char *drng_type);
+int lrng_drng_get(struct lrng_drng *drng, u8 *outbuf, u32 outbuflen);
+int lrng_drng_sleep_while_nonoperational(int nonblock);
+int lrng_drng_sleep_while_non_min_seeded(void);
+int lrng_drng_get_sleep(u8 *outbuf, u32 outbuflen, bool pr);
+void lrng_drng_seed_work(struct work_struct *dummy);
+void lrng_drng_force_reseed(void);
+void lrng_force_fully_seeded(void);
+
+static inline u32 lrng_compress_osr(void)
+{
+	return lrng_sp80090c_compliant() ? LRNG_OVERSAMPLE_ES_BITS : 0;
+}
+
+static inline u32 lrng_reduce_by_osr(u32 entropy_bits)
+{
+	u32 osr_bits = lrng_compress_osr();
+
+	return (entropy_bits >= osr_bits) ? (entropy_bits - osr_bits) : 0;
+}
+
+#endif /* _LRNG_DRNG_H */
diff --git a/drivers/char/lrng/lrng_es_aux.c b/drivers/char/lrng/lrng_es_aux.c
new file mode 100644
index 000000000..245bc8299
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_aux.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Slow Entropy Source: Auxiliary entropy pool
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+
+#include "lrng_es_aux.h"
+#include "lrng_es_mgr.h"
+#include "lrng_sysctl.h"
+
+/*
+ * This is the auxiliary pool
+ *
+ * The aux pool array is aligned to 8 bytes to comfort the kernel crypto API
+ * cipher implementations of the hash functions used to read the pool: for some
+ * accelerated implementations, we need an alignment to avoid a realignment
+ * which involves memcpy(). The alignment to 8 bytes should satisfy all crypto
+ * implementations.
+ */
+struct lrng_pool {
+	u8 aux_pool[LRNG_POOL_SIZE];	/* Aux pool: digest state */
+	atomic_t aux_entropy_bits;
+	atomic_t digestsize;		/* Digest size of used hash */
+	bool initialized;		/* Aux pool initialized? */
+
+	/* Serialize read of entropy pool and update of aux pool */
+	spinlock_t lock;
+};
+
+static struct lrng_pool lrng_pool __aligned(LRNG_KCAPI_ALIGN) = {
+	.aux_entropy_bits	= ATOMIC_INIT(0),
+	.digestsize		= ATOMIC_INIT(LRNG_ATOMIC_DIGEST_SIZE),
+	.initialized		= false,
+	.lock			= __SPIN_LOCK_UNLOCKED(lrng_pool.lock)
+};
+
+/********************************** Helper ***********************************/
+
+/* Entropy in bits present in aux pool */
+static u32 lrng_aux_avail_entropy(u32 __unused)
+{
+	/* Cap available entropy with max entropy */
+	u32 avail_bits = min_t(u32, lrng_get_digestsize(),
+			       atomic_read_u32(&lrng_pool.aux_entropy_bits));
+
+	/* Consider oversampling rate due to aux pool conditioning */
+	return lrng_reduce_by_osr(avail_bits);
+}
+
+/* Set the digest size of the used hash in bytes */
+static void lrng_set_digestsize(u32 digestsize)
+{
+	struct lrng_pool *pool = &lrng_pool;
+	u32 ent_bits = atomic_xchg_relaxed(&pool->aux_entropy_bits, 0),
+	    old_digestsize = lrng_get_digestsize();
+
+	atomic_set(&lrng_pool.digestsize, digestsize);
+
+	/*
+	 * Update the write wakeup threshold which must not be larger
+	 * than the digest size of the current conditioning hash.
+	 */
+	digestsize = lrng_reduce_by_osr(digestsize << 3);
+	lrng_sysctl_update_max_write_thresh(digestsize);
+	lrng_write_wakeup_bits = digestsize;
+
+	/*
+	 * In case the new digest is larger than the old one, cap the available
+	 * entropy to the old message digest used to process the existing data.
+	 */
+	ent_bits = min_t(u32, ent_bits, old_digestsize);
+	atomic_add(ent_bits, &pool->aux_entropy_bits);
+}
+
+static int __init lrng_init_wakeup_bits(void)
+{
+	u32 digestsize = lrng_reduce_by_osr(lrng_get_digestsize());
+
+	lrng_sysctl_update_max_write_thresh(digestsize);
+	lrng_write_wakeup_bits = digestsize;
+	return 0;
+}
+core_initcall(lrng_init_wakeup_bits);
+
+/* Obtain the digest size provided by the used hash in bits */
+u32 lrng_get_digestsize(void)
+{
+	return atomic_read_u32(&lrng_pool.digestsize) << 3;
+}
+
+/* Set entropy content in user-space controllable aux pool */
+void lrng_pool_set_entropy(u32 entropy_bits)
+{
+	atomic_set(&lrng_pool.aux_entropy_bits, entropy_bits);
+}
+
+static void lrng_aux_reset(void)
+{
+	lrng_pool_set_entropy(0);
+}
+
+/*
+ * Replace old with new hash for auxiliary pool handling
+ *
+ * Assumption: the caller must guarantee that the new_cb is available during the
+ * entire operation (e.g. it must hold the write lock against pointer updating).
+ */
+static int
+lrng_aux_switch_hash(struct lrng_drng *drng, int __unused,
+		     const struct lrng_hash_cb *new_cb, void *new_hash,
+		     const struct lrng_hash_cb *old_cb)
+{
+	struct lrng_drng *init_drng = lrng_drng_init_instance();
+	struct lrng_pool *pool = &lrng_pool;
+	struct shash_desc *shash = (struct shash_desc *)pool->aux_pool;
+	u8 digest[LRNG_MAX_DIGESTSIZE];
+	int ret;
+
+	if (!IS_ENABLED(CONFIG_LRNG_SWITCH))
+		return -EOPNOTSUPP;
+
+	if (unlikely(!pool->initialized))
+		return 0;
+
+	/* We only switch if the processed DRNG is the initial DRNG. */
+	if (init_drng != drng)
+		return 0;
+
+	/* Get the aux pool hash with old digest ... */
+	ret = old_cb->hash_final(shash, digest) ?:
+	      /* ... re-initialize the hash with the new digest ... */
+	      new_cb->hash_init(shash, new_hash) ?:
+	      /*
+	       * ... feed the old hash into the new state. We may feed
+	       * uninitialized memory into the new state, but this is
+	       * considered no issue and even good as we have some more
+	       * uncertainty here.
+	       */
+	      new_cb->hash_update(shash, digest, sizeof(digest));
+	if (!ret) {
+		lrng_set_digestsize(new_cb->hash_digestsize(new_hash));
+		pr_debug("Re-initialize aux entropy pool with hash %s\n",
+			 new_cb->hash_name());
+	}
+
+	memzero_explicit(digest, sizeof(digest));
+	return ret;
+}
+
+/* Insert data into auxiliary pool by using the hash update function. */
+static int
+lrng_aux_pool_insert_locked(const u8 *inbuf, u32 inbuflen, u32 entropy_bits)
+{
+	struct lrng_pool *pool = &lrng_pool;
+	struct shash_desc *shash = (struct shash_desc *)pool->aux_pool;
+	struct lrng_drng *drng = lrng_drng_init_instance();
+	const struct lrng_hash_cb *hash_cb;
+	unsigned long flags;
+	void *hash;
+	int ret;
+
+	entropy_bits = min_t(u32, entropy_bits, inbuflen << 3);
+
+	read_lock_irqsave(&drng->hash_lock, flags);
+	hash_cb = drng->hash_cb;
+	hash = drng->hash;
+
+	if (unlikely(!pool->initialized)) {
+		ret = hash_cb->hash_init(shash, hash);
+		if (ret)
+			goto out;
+		pool->initialized = true;
+	}
+
+	ret = hash_cb->hash_update(shash, inbuf, inbuflen);
+	if (ret)
+		goto out;
+
+	/*
+	 * Cap the available entropy to the hash output size compliant to
+	 * SP800-90B section 3.1.5.1 table 1.
+	 */
+	entropy_bits += atomic_read_u32(&pool->aux_entropy_bits);
+	atomic_set(&pool->aux_entropy_bits,
+		   min_t(u32, entropy_bits,
+			 hash_cb->hash_digestsize(hash) << 3));
+
+out:
+	read_unlock_irqrestore(&drng->hash_lock, flags);
+	return ret;
+}
+
+int lrng_pool_insert_aux(const u8 *inbuf, u32 inbuflen, u32 entropy_bits)
+{
+	struct lrng_pool *pool = &lrng_pool;
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&pool->lock, flags);
+	ret = lrng_aux_pool_insert_locked(inbuf, inbuflen, entropy_bits);
+	spin_unlock_irqrestore(&pool->lock, flags);
+
+	lrng_es_add_entropy();
+
+	return ret;
+}
+EXPORT_SYMBOL(lrng_pool_insert_aux);
+
+/************************* Get data from entropy pool *************************/
+
+/*
+ * Get auxiliary entropy pool and its entropy content for seed buffer.
+ * Caller must hold lrng_pool.pool->lock.
+ * @outbuf: buffer to store data in with size requested_bits
+ * @requested_bits: Requested amount of entropy
+ * @return: amount of entropy in outbuf in bits.
+ */
+static u32 lrng_aux_get_pool(u8 *outbuf, u32 requested_bits)
+{
+	struct lrng_pool *pool = &lrng_pool;
+	struct shash_desc *shash = (struct shash_desc *)pool->aux_pool;
+	struct lrng_drng *drng = lrng_drng_init_instance();
+	const struct lrng_hash_cb *hash_cb;
+	unsigned long flags;
+	void *hash;
+	u32 collected_ent_bits, returned_ent_bits, unused_bits = 0,
+	    digestsize, digestsize_bits, requested_bits_osr;
+	u8 aux_output[LRNG_MAX_DIGESTSIZE];
+
+	if (unlikely(!pool->initialized))
+		return 0;
+
+	read_lock_irqsave(&drng->hash_lock, flags);
+
+	hash_cb = drng->hash_cb;
+	hash = drng->hash;
+	digestsize = hash_cb->hash_digestsize(hash);
+	digestsize_bits = digestsize << 3;
+
+	/* Cap to maximum entropy that can ever be generated with given hash */
+	lrng_cap_requested(digestsize_bits, requested_bits);
+
+	/* Ensure that no more than the size of aux_pool can be requested */
+	requested_bits = min_t(u32, requested_bits, (LRNG_MAX_DIGESTSIZE << 3));
+	requested_bits_osr = requested_bits + lrng_compress_osr();
+
+	/* Cap entropy with entropy counter from aux pool and the used digest */
+	collected_ent_bits = min_t(u32, digestsize_bits,
+			       atomic_xchg_relaxed(&pool->aux_entropy_bits, 0));
+
+	/* We collected too much entropy and put the overflow back */
+	if (collected_ent_bits > requested_bits_osr) {
+		/* Amount of bits we collected too much */
+		unused_bits = collected_ent_bits - requested_bits_osr;
+		/* Put entropy back */
+		atomic_add(unused_bits, &pool->aux_entropy_bits);
+		/* Fix collected entropy */
+		collected_ent_bits = requested_bits_osr;
+	}
+
+	/* Apply oversampling: discount requested oversampling rate */
+	returned_ent_bits = lrng_reduce_by_osr(collected_ent_bits);
+
+	pr_debug("obtained %u bits by collecting %u bits of entropy from aux pool, %u bits of entropy remaining\n",
+		 returned_ent_bits, collected_ent_bits, unused_bits);
+
+	/* Get the digest for the aux pool to be returned to the caller ... */
+	if (hash_cb->hash_final(shash, aux_output) ||
+	    /*
+	     * ... and re-initialize the aux state. Do not add the aux pool
+	     * digest for backward secrecy as it will be added with the
+	     * insertion of the complete seed buffer after it has been filled.
+	     */
+	    hash_cb->hash_init(shash, hash)) {
+		returned_ent_bits = 0;
+	} else {
+		/*
+		 * Do not truncate the output size exactly to collected_ent_bits
+		 * as the aux pool may contain data that is not credited with
+		 * entropy, but we want to use them to stir the DRNG state.
+		 */
+		memcpy(outbuf, aux_output, requested_bits >> 3);
+	}
+
+	read_unlock_irqrestore(&drng->hash_lock, flags);
+	memzero_explicit(aux_output, digestsize);
+	return returned_ent_bits;
+}
+
+static void lrng_aux_get_backtrack(struct entropy_buf *eb, u32 requested_bits,
+				   bool __unused)
+{
+	struct lrng_pool *pool = &lrng_pool;
+	unsigned long flags;
+
+	/* Ensure aux pool extraction and backtracking op are atomic */
+	spin_lock_irqsave(&pool->lock, flags);
+
+	eb->e_bits[lrng_ext_es_aux] = lrng_aux_get_pool(eb->e[lrng_ext_es_aux],
+							requested_bits);
+
+	/* Mix the extracted data back into pool for backtracking resistance */
+	if (lrng_aux_pool_insert_locked((u8 *)eb,
+					sizeof(struct entropy_buf), 0))
+		pr_warn("Backtracking resistance operation failed\n");
+
+	spin_unlock_irqrestore(&pool->lock, flags);
+}
+
+static void lrng_aux_es_state(unsigned char *buf, size_t buflen)
+{
+	const struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+
+	/* Assume the lrng_drng_init lock is taken by caller */
+	snprintf(buf, buflen,
+		 " Hash for operating entropy pool: %s\n"
+		 " Available entropy: %u\n",
+		 lrng_drng_init->hash_cb->hash_name(),
+		 lrng_aux_avail_entropy(0));
+}
+
+struct lrng_es_cb lrng_es_aux = {
+	.name			= "Auxiliary",
+	.get_ent		= lrng_aux_get_backtrack,
+	.curr_entropy		= lrng_aux_avail_entropy,
+	.max_entropy		= lrng_get_digestsize,
+	.state			= lrng_aux_es_state,
+	.reset			= lrng_aux_reset,
+	.switch_hash		= lrng_aux_switch_hash,
+};
diff --git a/drivers/char/lrng/lrng_es_aux.h b/drivers/char/lrng/lrng_es_aux.h
new file mode 100644
index 000000000..bc41e6474
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_aux.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_AUX_H
+#define _LRNG_ES_AUX_H
+
+#include "lrng_drng_mgr.h"
+#include "lrng_es_mgr_cb.h"
+
+u32 lrng_get_digestsize(void);
+void lrng_pool_set_entropy(u32 entropy_bits);
+int lrng_pool_insert_aux(const u8 *inbuf, u32 inbuflen, u32 entropy_bits);
+
+extern struct lrng_es_cb lrng_es_aux;
+
+/****************************** Helper code ***********************************/
+
+/* Obtain the security strength of the LRNG in bits */
+static inline u32 lrng_security_strength(void)
+{
+	/*
+	 * We use a hash to read the entropy in the entropy pool. According to
+	 * SP800-90B table 1, the entropy can be at most the digest size.
+	 * Considering this together with the last sentence in section 3.1.5.1.2
+	 * the security strength of a (approved) hash is equal to its output
+	 * size. On the other hand the entropy cannot be larger than the
+	 * security strength of the used DRBG.
+	 */
+	return min_t(u32, LRNG_FULL_SEED_ENTROPY_BITS, lrng_get_digestsize());
+}
+
+static inline u32 lrng_get_seed_entropy_osr(bool fully_seeded)
+{
+	u32 requested_bits = lrng_security_strength();
+
+	/* Apply oversampling during initialization according to SP800-90C */
+	if (lrng_sp80090c_compliant() && !fully_seeded)
+		requested_bits += LRNG_SEED_BUFFER_INIT_ADD_BITS;
+	return requested_bits;
+}
+
+#endif /* _LRNG_ES_AUX_H */
diff --git a/drivers/char/lrng/lrng_es_cpu.c b/drivers/char/lrng/lrng_es_cpu.c
new file mode 100644
index 000000000..96a621c16
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_cpu.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Fast Entropy Source: CPU-based entropy source
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <crypto/hash.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <asm/archrandom.h>
+
+#include "lrng_definitions.h"
+#include "lrng_es_aux.h"
+#include "lrng_es_cpu.h"
+
+/*
+ * Estimated entropy of data is a 32th of LRNG_DRNG_SECURITY_STRENGTH_BITS.
+ * As we have no ability to review the implementation of those noise sources,
+ * it is prudent to have a conservative estimate here.
+ */
+#define LRNG_ARCHRANDOM_DEFAULT_STRENGTH CONFIG_LRNG_CPU_ENTROPY_RATE
+#define LRNG_ARCHRANDOM_TRUST_CPU_STRENGTH LRNG_DRNG_SECURITY_STRENGTH_BITS
+#ifdef CONFIG_RANDOM_TRUST_CPU
+static u32 cpu_entropy = LRNG_ARCHRANDOM_TRUST_CPU_STRENGTH;
+#else
+static u32 cpu_entropy = LRNG_ARCHRANDOM_DEFAULT_STRENGTH;
+#endif
+#ifdef CONFIG_LRNG_RUNTIME_ES_CONFIG
+module_param(cpu_entropy, uint, 0644);
+MODULE_PARM_DESC(cpu_entropy, "Entropy in bits of 256 data bits from CPU noise source (e.g. RDSEED)");
+#endif
+
+static int __init lrng_parse_trust_cpu(char *arg)
+{
+	int ret;
+	bool trust_cpu = false;
+
+	ret = kstrtobool(arg, &trust_cpu);
+	if (ret)
+		return ret;
+
+	if (trust_cpu)
+		cpu_entropy = LRNG_ARCHRANDOM_TRUST_CPU_STRENGTH;
+	else
+		cpu_entropy = LRNG_ARCHRANDOM_DEFAULT_STRENGTH;
+
+	lrng_force_fully_seeded();
+
+	return 0;
+}
+early_param("random.trust_cpu", lrng_parse_trust_cpu);
+
+static u32 lrng_cpu_entropylevel(u32 requested_bits)
+{
+	return lrng_fast_noise_entropylevel(cpu_entropy, requested_bits);
+}
+
+static u32 lrng_cpu_poolsize(void)
+{
+	return lrng_cpu_entropylevel(lrng_security_strength());
+}
+
+static u32 lrng_get_cpu_data(u8 *outbuf, u32 requested_bits)
+{
+	size_t longs = 0;
+	u32 i,  req = requested_bits >> 3;
+
+	/* operate on full blocks */
+	BUILD_BUG_ON(LRNG_DRNG_SECURITY_STRENGTH_BYTES % sizeof(unsigned long));
+	BUILD_BUG_ON(LRNG_SEED_BUFFER_INIT_ADD_BITS % sizeof(unsigned long));
+	/* ensure we have aligned buffers */
+	BUILD_BUG_ON(LRNG_KCAPI_ALIGN % sizeof(unsigned long));
+
+	for (i = 0; i < req; i += longs) {
+		longs = arch_get_random_seed_longs(
+			(unsigned long *)(outbuf + i), req - i);
+		if (longs)
+			continue;
+		longs = arch_get_random_longs((unsigned long *)(outbuf + i),
+					      req - i);
+		if (!longs) {
+			cpu_entropy = 0;
+			return 0;
+		}
+	}
+
+	return requested_bits;
+}
+
+static u32 lrng_get_cpu_data_compress(u8 *outbuf, u32 requested_bits,
+				      u32 data_multiplier)
+{
+	SHASH_DESC_ON_STACK(shash, NULL);
+	const struct lrng_hash_cb *hash_cb;
+	struct lrng_drng *drng = lrng_drng_node_instance();
+	unsigned long flags;
+	u32 ent_bits = 0, i, partial_bits = 0, digestsize, digestsize_bits,
+	    full_bits;
+	void *hash;
+
+	read_lock_irqsave(&drng->hash_lock, flags);
+	hash_cb = drng->hash_cb;
+	hash = drng->hash;
+
+	digestsize = hash_cb->hash_digestsize(hash);
+	digestsize_bits = digestsize << 3;
+	/* Cap to maximum entropy that can ever be generated with given hash */
+	lrng_cap_requested(digestsize_bits, requested_bits);
+	full_bits = requested_bits * data_multiplier;
+
+	/* Calculate oversampling for SP800-90C */
+	if (lrng_sp80090c_compliant()) {
+		/* Complete amount of bits to be pulled */
+		full_bits += LRNG_OVERSAMPLE_ES_BITS * data_multiplier;
+		/* Full blocks that will be pulled */
+		data_multiplier = full_bits / requested_bits;
+		/* Partial block in bits to be pulled */
+		partial_bits = full_bits - (data_multiplier * requested_bits);
+	}
+
+	if (hash_cb->hash_init(shash, hash))
+		goto out;
+
+	/* Hash all data from the CPU entropy source */
+	for (i = 0; i < data_multiplier; i++) {
+		ent_bits = lrng_get_cpu_data(outbuf, requested_bits);
+		if (!ent_bits)
+			goto out;
+
+		if (hash_cb->hash_update(shash, outbuf, ent_bits >> 3))
+			goto err;
+	}
+
+	/* Hash partial block, if applicable */
+	ent_bits = lrng_get_cpu_data(outbuf, partial_bits);
+	if (ent_bits &&
+	    hash_cb->hash_update(shash, outbuf, ent_bits >> 3))
+		goto err;
+
+	pr_debug("pulled %u bits from CPU RNG entropy source\n", full_bits);
+	ent_bits = requested_bits;
+
+	/* Generate the compressed data to be returned to the caller */
+	if (requested_bits < digestsize_bits) {
+		u8 digest[LRNG_MAX_DIGESTSIZE];
+
+		if (hash_cb->hash_final(shash, digest))
+			goto err;
+
+		/* Truncate output data to requested size */
+		memcpy(outbuf, digest, requested_bits >> 3);
+		memzero_explicit(digest, digestsize);
+	} else {
+		if (hash_cb->hash_final(shash, outbuf))
+			goto err;
+	}
+
+out:
+	hash_cb->hash_desc_zero(shash);
+	read_unlock_irqrestore(&drng->hash_lock, flags);
+	return ent_bits;
+
+err:
+	ent_bits = 0;
+	goto out;
+}
+
+/*
+ * If CPU entropy source requires does not return full entropy, return the
+ * multiplier of how much data shall be sampled from it.
+ */
+static u32 lrng_cpu_multiplier(void)
+{
+	static u32 data_multiplier = 0;
+	unsigned long v;
+
+	if (data_multiplier > 0)
+		return data_multiplier;
+
+	if (IS_ENABLED(CONFIG_X86) && !arch_get_random_seed_longs(&v, 1)) {
+		/*
+		 * Intel SPEC: pulling 512 blocks from RDRAND ensures
+		 * one reseed making it logically equivalent to RDSEED.
+		 */
+		data_multiplier = 512;
+	} else if (IS_ENABLED(CONFIG_PPC)) {
+		/*
+		 * PowerISA defines DARN to deliver at least 0.5 bits of
+		 * entropy per data bit.
+		 */
+		data_multiplier = 2;
+	} else if (IS_ENABLED(CONFIG_RISCV)) {
+		/*
+		 * riscv-crypto-spec-scalar-1.0.0-rc6.pdf section 4.2 defines
+		 * this requirement.
+		 */
+		data_multiplier = 2;
+	} else {
+		/* CPU provides full entropy */
+		data_multiplier = CONFIG_LRNG_CPU_FULL_ENT_MULTIPLIER;
+	}
+	return data_multiplier;
+}
+
+static int
+lrng_cpu_switch_hash(struct lrng_drng *drng, int node,
+		     const struct lrng_hash_cb *new_cb, void *new_hash,
+		     const struct lrng_hash_cb *old_cb)
+{
+	u32 digestsize, multiplier;
+
+	if (!IS_ENABLED(CONFIG_LRNG_SWITCH))
+		return -EOPNOTSUPP;
+
+	digestsize = lrng_get_digestsize();
+	multiplier = lrng_cpu_multiplier();
+
+	/*
+	 * It would be security violation if the new digestsize is smaller than
+	 * the set CPU entropy rate.
+	 */
+	WARN_ON(multiplier > 1 && digestsize < cpu_entropy);
+	cpu_entropy = min_t(u32, digestsize, cpu_entropy);
+	return 0;
+}
+
+/*
+ * lrng_get_arch() - Get CPU entropy source entropy
+ *
+ * @eb: entropy buffer to store entropy
+ * @requested_bits: requested entropy in bits
+ */
+static void lrng_cpu_get(struct entropy_buf *eb, u32 requested_bits,
+			 bool __unused)
+{
+	u32 ent_bits, data_multiplier = lrng_cpu_multiplier();
+
+	if (data_multiplier <= 1) {
+		ent_bits = lrng_get_cpu_data(eb->e[lrng_ext_es_cpu],
+					     requested_bits);
+	} else {
+		ent_bits = lrng_get_cpu_data_compress(eb->e[lrng_ext_es_cpu],
+						      requested_bits,
+						      data_multiplier);
+	}
+
+	ent_bits = lrng_cpu_entropylevel(ent_bits);
+	pr_debug("obtained %u bits of entropy from CPU RNG entropy source\n",
+		 ent_bits);
+	eb->e_bits[lrng_ext_es_cpu] = ent_bits;
+}
+
+static void lrng_cpu_es_state(unsigned char *buf, size_t buflen)
+{
+	const struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+	u32 data_multiplier = lrng_cpu_multiplier();
+
+	/* Assume the lrng_drng_init lock is taken by caller */
+	snprintf(buf, buflen,
+		 " Hash for compressing data: %s\n"
+		 " Available entropy: %u\n"
+		 " Data multiplier: %u\n",
+		 (data_multiplier <= 1) ?
+			"N/A" : lrng_drng_init->hash_cb->hash_name(),
+		 lrng_cpu_poolsize(),
+		 data_multiplier);
+}
+
+struct lrng_es_cb lrng_es_cpu = {
+	.name			= "CPU",
+	.get_ent		= lrng_cpu_get,
+	.curr_entropy		= lrng_cpu_entropylevel,
+	.max_entropy		= lrng_cpu_poolsize,
+	.state			= lrng_cpu_es_state,
+	.reset			= NULL,
+	.switch_hash		= lrng_cpu_switch_hash,
+};
diff --git a/drivers/char/lrng/lrng_es_cpu.h b/drivers/char/lrng/lrng_es_cpu.h
new file mode 100644
index 000000000..8dbb4d9a2
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_cpu.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_CPU_H
+#define _LRNG_ES_CPU_H
+
+#include "lrng_es_mgr_cb.h"
+
+#ifdef CONFIG_LRNG_CPU
+
+extern struct lrng_es_cb lrng_es_cpu;
+
+#endif /* CONFIG_LRNG_CPU */
+
+#endif /* _LRNG_ES_CPU_H */
diff --git a/drivers/char/lrng/lrng_es_irq.c b/drivers/char/lrng/lrng_es_irq.c
new file mode 100644
index 000000000..4eb12872c
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_irq.c
@@ -0,0 +1,730 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Slow Entropy Source: Interrupt data collection
+ *
+ * Copyright (C) 2022 - 2023, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <asm/irq_regs.h>
+#include <asm/ptrace.h>
+#include <crypto/hash.h>
+#include <linux/gcd.h>
+#include <linux/module.h>
+#include <linux/random.h>
+
+#include "lrng_es_aux.h"
+#include "lrng_es_irq.h"
+#include "lrng_es_timer_common.h"
+#include "lrng_health.h"
+#include "lrng_numa.h"
+#include "lrng_testing.h"
+
+/*
+ * Number of interrupts to be recorded to assume that DRNG security strength
+ * bits of entropy are received.
+ * Note: a value below the DRNG security strength should not be defined as this
+ *	 may imply the DRNG can never be fully seeded in case other noise
+ *	 sources are unavailable.
+ */
+#define LRNG_IRQ_ENTROPY_BITS LRNG_UINT32_C(CONFIG_LRNG_IRQ_ENTROPY_RATE)
+
+
+/* Number of interrupts required for LRNG_DRNG_SECURITY_STRENGTH_BITS entropy */
+static u32 lrng_irq_entropy_bits = LRNG_IRQ_ENTROPY_BITS;
+
+static u32 irq_entropy __read_mostly = LRNG_IRQ_ENTROPY_BITS;
+#ifdef CONFIG_LRNG_RUNTIME_ES_CONFIG
+module_param(irq_entropy, uint, 0444);
+MODULE_PARM_DESC(irq_entropy,
+		 "How many interrupts must be collected for obtaining 256 bits of entropy\n");
+#endif
+
+/* Per-CPU array holding concatenated IRQ entropy events */
+static DEFINE_PER_CPU(u32 [LRNG_DATA_ARRAY_SIZE], lrng_irq_array)
+						__aligned(LRNG_KCAPI_ALIGN);
+static DEFINE_PER_CPU(u32, lrng_irq_array_ptr) = 0;
+static DEFINE_PER_CPU(atomic_t, lrng_irq_array_irqs) = ATOMIC_INIT(0);
+
+/*
+ * The entropy collection is performed by executing the following steps:
+ * 1. fill up the per-CPU array holding the time stamps
+ * 2. once the per-CPU array is full, a compression of the data into
+ *    the entropy pool is performed - this happens in interrupt context
+ *
+ * If step 2 is not desired in interrupt context, the following boolean
+ * needs to be set to false. This implies that old entropy data in the
+ * per-CPU array collected since the last DRNG reseed is overwritten with
+ * new entropy data instead of retaining the entropy with the compression
+ * operation.
+ *
+ * Impact on entropy:
+ *
+ * If continuous compression is enabled, the maximum entropy that is collected
+ * per CPU between DRNG reseeds is equal to the digest size of the used hash.
+ *
+ * If continuous compression is disabled, the maximum number of entropy events
+ * that can be collected per CPU is equal to LRNG_DATA_ARRAY_SIZE. This amount
+ * of events is converted into an entropy statement which then represents the
+ * maximum amount of entropy collectible per CPU between DRNG reseeds.
+ */
+static bool lrng_irq_continuous_compression __read_mostly =
+			IS_ENABLED(CONFIG_LRNG_ENABLE_CONTINUOUS_COMPRESSION);
+
+#ifdef CONFIG_LRNG_SWITCHABLE_CONTINUOUS_COMPRESSION
+module_param(lrng_irq_continuous_compression, bool, 0444);
+MODULE_PARM_DESC(lrng_irq_continuous_compression,
+		 "Perform entropy compression if per-CPU entropy data array is full\n");
+#endif
+
+/*
+ * Per-CPU entropy pool with compressed entropy event
+ *
+ * The per-CPU entropy pool is defined as the hash state. New data is simply
+ * inserted into the entropy pool by performing a hash update operation.
+ * To read the entropy pool, a hash final must be invoked. However, before
+ * the entropy pool is released again after a hash final, the hash init must
+ * be performed.
+ */
+static DEFINE_PER_CPU(u8 [LRNG_POOL_SIZE], lrng_irq_pool)
+						__aligned(LRNG_KCAPI_ALIGN);
+/*
+ * Lock to allow other CPUs to read the pool - as this is only done during
+ * reseed which is infrequent, this lock is hardly contended.
+ */
+static DEFINE_PER_CPU(spinlock_t, lrng_irq_lock);
+static DEFINE_PER_CPU(bool, lrng_irq_lock_init) = false;
+
+static bool lrng_irq_pool_online(int cpu)
+{
+	return per_cpu(lrng_irq_lock_init, cpu);
+}
+
+static void __init lrng_irq_check_compression_state(void)
+{
+	/* One pool must hold sufficient entropy for disabled compression */
+	if (!lrng_irq_continuous_compression) {
+		u32 max_ent = min_t(u32, lrng_get_digestsize(),
+				    lrng_data_to_entropy(LRNG_DATA_NUM_VALUES,
+							lrng_irq_entropy_bits));
+		if (max_ent < lrng_security_strength()) {
+			pr_warn("Force continuous compression operation to ensure LRNG can hold enough entropy\n");
+			lrng_irq_continuous_compression = true;
+		}
+	}
+}
+
+void __init lrng_irq_es_init(bool highres_timer)
+{
+	/* Set a minimum number of interrupts that must be collected */
+	irq_entropy = max_t(u32, LRNG_IRQ_ENTROPY_BITS, irq_entropy);
+
+	if (highres_timer) {
+		lrng_irq_entropy_bits = irq_entropy;
+	} else {
+		u32 new_entropy = irq_entropy * LRNG_ES_OVERSAMPLING_FACTOR;
+
+		lrng_irq_entropy_bits = (irq_entropy < new_entropy) ?
+					 new_entropy : irq_entropy;
+		pr_warn("operating without high-resolution timer and applying IRQ oversampling factor %u\n",
+			LRNG_ES_OVERSAMPLING_FACTOR);
+	}
+
+	lrng_irq_check_compression_state();
+}
+
+/*
+ * Reset all per-CPU pools - reset entropy estimator but leave the pool data
+ * that may or may not have entropy unchanged.
+ */
+static void lrng_irq_reset(void)
+{
+	int cpu;
+
+	/* Trigger GCD calculation anew. */
+	lrng_gcd_set(0);
+
+	for_each_online_cpu(cpu)
+		atomic_set(per_cpu_ptr(&lrng_irq_array_irqs, cpu), 0);
+}
+
+static u32 lrng_irq_avail_pool_size(void)
+{
+	u32 max_size = 0, max_pool = lrng_get_digestsize();
+	int cpu;
+
+	if (!lrng_irq_continuous_compression)
+		max_pool = min_t(u32, max_pool, LRNG_DATA_NUM_VALUES);
+
+	for_each_online_cpu(cpu) {
+		if (lrng_irq_pool_online(cpu))
+			max_size += max_pool;
+	}
+
+	return max_size;
+}
+
+/* Return entropy of unused IRQs present in all per-CPU pools. */
+static u32 lrng_irq_avail_entropy(u32 __unused)
+{
+	u32 digestsize_irqs, irq = 0;
+	int cpu;
+
+	/* Only deliver entropy when SP800-90B self test is completed */
+	if (!lrng_sp80090b_startup_complete_es(lrng_int_es_irq))
+		return 0;
+
+	/* Obtain the cap of maximum numbers of IRQs we count */
+	digestsize_irqs = lrng_entropy_to_data(lrng_get_digestsize(),
+					       lrng_irq_entropy_bits);
+	if (!lrng_irq_continuous_compression) {
+		/* Cap to max. number of IRQs the array can hold */
+		digestsize_irqs = min_t(u32, digestsize_irqs,
+					LRNG_DATA_NUM_VALUES);
+	}
+
+	for_each_online_cpu(cpu) {
+		if (!lrng_irq_pool_online(cpu))
+			continue;
+		irq += min_t(u32, digestsize_irqs,
+			     atomic_read_u32(per_cpu_ptr(&lrng_irq_array_irqs,
+							 cpu)));
+	}
+
+	/* Consider oversampling rate */
+	return lrng_reduce_by_osr(lrng_data_to_entropy(irq,
+						       lrng_irq_entropy_bits));
+}
+
+/*
+ * Trigger a switch of the hash implementation for the per-CPU pool.
+ *
+ * For each per-CPU pool, obtain the message digest with the old hash
+ * implementation, initialize the per-CPU pool again with the new hash
+ * implementation and inject the message digest into the new state.
+ *
+ * Assumption: the caller must guarantee that the new_cb is available during the
+ * entire operation (e.g. it must hold the lock against pointer updating).
+ */
+static int
+lrng_irq_switch_hash(struct lrng_drng *drng, int node,
+		     const struct lrng_hash_cb *new_cb, void *new_hash,
+		     const struct lrng_hash_cb *old_cb)
+{
+	u8 digest[LRNG_MAX_DIGESTSIZE];
+	u32 digestsize_irqs, found_irqs;
+	int ret = 0, cpu;
+
+	if (!IS_ENABLED(CONFIG_LRNG_SWITCH))
+		return -EOPNOTSUPP;
+
+	for_each_online_cpu(cpu) {
+		struct shash_desc *pcpu_shash;
+
+		/*
+		 * Only switch the per-CPU pools for the current node because
+		 * the hash_cb only applies NUMA-node-wide.
+		 */
+		if (cpu_to_node(cpu) != node || !lrng_irq_pool_online(cpu))
+			continue;
+
+		pcpu_shash = (struct shash_desc *)per_cpu_ptr(lrng_irq_pool,
+							      cpu);
+
+		digestsize_irqs = old_cb->hash_digestsize(pcpu_shash);
+		digestsize_irqs = lrng_entropy_to_data(digestsize_irqs << 3,
+						       lrng_irq_entropy_bits);
+
+		if (pcpu_shash->tfm == new_hash)
+			continue;
+
+		/* Get the per-CPU pool hash with old digest ... */
+		ret = old_cb->hash_final(pcpu_shash, digest) ?:
+		      /* ... re-initialize the hash with the new digest ... */
+		      new_cb->hash_init(pcpu_shash, new_hash) ?:
+		      /*
+		       * ... feed the old hash into the new state. We may feed
+		       * uninitialized memory into the new state, but this is
+		       * considered no issue and even good as we have some more
+		       * uncertainty here.
+		       */
+		      new_cb->hash_update(pcpu_shash, digest, sizeof(digest));
+		if (ret)
+			goto out;
+
+		/*
+		 * In case the new digest is larger than the old one, cap
+		 * the available entropy to the old message digest used to
+		 * process the existing data.
+		 */
+		found_irqs = atomic_xchg_relaxed(
+				per_cpu_ptr(&lrng_irq_array_irqs, cpu), 0);
+		found_irqs = min_t(u32, found_irqs, digestsize_irqs);
+		atomic_add_return_relaxed(found_irqs,
+				per_cpu_ptr(&lrng_irq_array_irqs, cpu));
+
+		pr_debug("Re-initialize per-CPU interrupt entropy pool for CPU %d on NUMA node %d with hash %s\n",
+			 cpu, node, new_cb->hash_name());
+	}
+
+out:
+	memzero_explicit(digest, sizeof(digest));
+	return ret;
+}
+
+/*
+ * When reading the per-CPU message digest, make sure we use the crypto
+ * callbacks defined for the NUMA node the per-CPU pool is defined for because
+ * the LRNG crypto switch support is only atomic per NUMA node.
+ */
+static u32
+lrng_irq_pool_hash_one(const struct lrng_hash_cb *pcpu_hash_cb,
+		       void *pcpu_hash, int cpu, u8 *digest, u32 *digestsize)
+{
+	struct shash_desc *pcpu_shash =
+		(struct shash_desc *)per_cpu_ptr(lrng_irq_pool, cpu);
+	spinlock_t *lock = per_cpu_ptr(&lrng_irq_lock, cpu);
+	unsigned long flags;
+	u32 digestsize_irqs, found_irqs;
+
+	/* Lock guarding against reading / writing to per-CPU pool */
+	spin_lock_irqsave(lock, flags);
+
+	*digestsize = pcpu_hash_cb->hash_digestsize(pcpu_hash);
+	digestsize_irqs = lrng_entropy_to_data(*digestsize << 3,
+					       lrng_irq_entropy_bits);
+
+	/* Obtain entropy statement like for the entropy pool */
+	found_irqs = atomic_xchg_relaxed(
+				per_cpu_ptr(&lrng_irq_array_irqs, cpu), 0);
+	/* Cap to maximum amount of data we can hold in hash */
+	found_irqs = min_t(u32, found_irqs, digestsize_irqs);
+
+	/* Cap to maximum amount of data we can hold in array */
+	if (!lrng_irq_continuous_compression)
+		found_irqs = min_t(u32, found_irqs, LRNG_DATA_NUM_VALUES);
+
+	/* Store all not-yet compressed data in data array into hash, ... */
+	if (pcpu_hash_cb->hash_update(pcpu_shash,
+				(u8 *)per_cpu_ptr(lrng_irq_array, cpu),
+				LRNG_DATA_ARRAY_SIZE * sizeof(u32)) ?:
+	    /* ... get the per-CPU pool digest, ... */
+	    pcpu_hash_cb->hash_final(pcpu_shash, digest) ?:
+	    /* ... re-initialize the hash, ... */
+	    pcpu_hash_cb->hash_init(pcpu_shash, pcpu_hash) ?:
+	    /* ... feed the old hash into the new state. */
+	    pcpu_hash_cb->hash_update(pcpu_shash, digest, *digestsize))
+		found_irqs = 0;
+
+	spin_unlock_irqrestore(lock, flags);
+	return found_irqs;
+}
+
+/*
+ * Hash all per-CPU pools and return the digest to be used as seed data for
+ * seeding a DRNG. The caller must guarantee backtracking resistance.
+ * The function will only copy as much data as entropy is available into the
+ * caller-provided output buffer.
+ *
+ * This function handles the translation from the number of received interrupts
+ * into an entropy statement. The conversion depends on LRNG_IRQ_ENTROPY_BITS
+ * which defines how many interrupts must be received to obtain 256 bits of
+ * entropy. With this value, the function lrng_data_to_entropy converts a given
+ * data size (received interrupts, requested amount of data, etc.) into an
+ * entropy statement. lrng_entropy_to_data does the reverse.
+ *
+ * @eb: entropy buffer to store entropy
+ * @requested_bits: Requested amount of entropy
+ * @fully_seeded: indicator whether LRNG is fully seeded
+ */
+static void lrng_irq_pool_hash(struct entropy_buf *eb, u32 requested_bits,
+			       bool fully_seeded)
+{
+	SHASH_DESC_ON_STACK(shash, NULL);
+	const struct lrng_hash_cb *hash_cb;
+	struct lrng_drng **lrng_drng = lrng_drng_instances();
+	struct lrng_drng *drng = lrng_drng_init_instance();
+	u8 digest[LRNG_MAX_DIGESTSIZE];
+	unsigned long flags, flags2;
+	u32 found_irqs, collected_irqs = 0, collected_ent_bits, requested_irqs,
+	    returned_ent_bits;
+	int ret, cpu;
+	void *hash;
+
+	/* Only deliver entropy when SP800-90B self test is completed */
+	if (!lrng_sp80090b_startup_complete_es(lrng_int_es_irq)) {
+		eb->e_bits[lrng_int_es_irq] = 0;
+		return;
+	}
+
+	/* Lock guarding replacement of per-NUMA hash */
+	read_lock_irqsave(&drng->hash_lock, flags);
+
+	hash_cb = drng->hash_cb;
+	hash = drng->hash;
+
+	/* The hash state of filled with all per-CPU pool hashes. */
+	ret = hash_cb->hash_init(shash, hash);
+	if (ret)
+		goto err;
+
+	/* Cap to maximum entropy that can ever be generated with given hash */
+	lrng_cap_requested(hash_cb->hash_digestsize(hash) << 3, requested_bits);
+	requested_irqs = lrng_entropy_to_data(requested_bits +
+					      lrng_compress_osr(),
+					      lrng_irq_entropy_bits);
+
+	/*
+	 * Harvest entropy from each per-CPU hash state - even though we may
+	 * have collected sufficient entropy, we will hash all per-CPU pools.
+	 */
+	for_each_online_cpu(cpu) {
+		struct lrng_drng *pcpu_drng = drng;
+		u32 digestsize, pcpu_unused_irqs = 0;
+		int node = cpu_to_node(cpu);
+
+		/* If pool is not online, then no entropy is present. */
+		if (!lrng_irq_pool_online(cpu))
+			continue;
+
+		if (lrng_drng && lrng_drng[node])
+			pcpu_drng = lrng_drng[node];
+
+		if (pcpu_drng == drng) {
+			found_irqs = lrng_irq_pool_hash_one(hash_cb, hash,
+							    cpu, digest,
+							    &digestsize);
+		} else {
+			read_lock_irqsave(&pcpu_drng->hash_lock, flags2);
+			found_irqs =
+				lrng_irq_pool_hash_one(pcpu_drng->hash_cb,
+						       pcpu_drng->hash, cpu,
+						       digest, &digestsize);
+			read_unlock_irqrestore(&pcpu_drng->hash_lock, flags2);
+		}
+
+		/* Inject the digest into the state of all per-CPU pools */
+		ret = hash_cb->hash_update(shash, digest, digestsize);
+		if (ret)
+			goto err;
+
+		collected_irqs += found_irqs;
+		if (collected_irqs > requested_irqs) {
+			pcpu_unused_irqs = collected_irqs - requested_irqs;
+			atomic_add_return_relaxed(pcpu_unused_irqs,
+				per_cpu_ptr(&lrng_irq_array_irqs, cpu));
+			collected_irqs = requested_irqs;
+		}
+		pr_debug("%u interrupts used from entropy pool of CPU %d, %u interrupts remain unused\n",
+			 found_irqs - pcpu_unused_irqs, cpu, pcpu_unused_irqs);
+	}
+
+	ret = hash_cb->hash_final(shash, digest);
+	if (ret)
+		goto err;
+
+	collected_ent_bits = lrng_data_to_entropy(collected_irqs,
+						  lrng_irq_entropy_bits);
+	/* Apply oversampling: discount requested oversampling rate */
+	returned_ent_bits = lrng_reduce_by_osr(collected_ent_bits);
+
+	pr_debug("obtained %u bits by collecting %u bits of entropy from entropy pool noise source\n",
+		 returned_ent_bits, collected_ent_bits);
+
+	/*
+	 * Truncate to available entropy as implicitly allowed by SP800-90B
+	 * section 3.1.5.1.1 table 1 which awards truncated hashes full
+	 * entropy.
+	 *
+	 * During boot time, we read requested_bits data with
+	 * returned_ent_bits entropy. In case our conservative entropy
+	 * estimate underestimates the available entropy we can transport as
+	 * much available entropy as possible.
+	 */
+	memcpy(eb->e[lrng_int_es_irq], digest,
+	       fully_seeded ? returned_ent_bits >> 3 : requested_bits >> 3);
+	eb->e_bits[lrng_int_es_irq] = returned_ent_bits;
+
+out:
+	hash_cb->hash_desc_zero(shash);
+	read_unlock_irqrestore(&drng->hash_lock, flags);
+	memzero_explicit(digest, sizeof(digest));
+	return;
+
+err:
+	eb->e_bits[lrng_int_es_irq] = 0;
+	goto out;
+}
+
+/* Compress the lrng_irq_array array into lrng_irq_pool */
+static void lrng_irq_array_compress(void)
+{
+	struct shash_desc *shash =
+			(struct shash_desc *)this_cpu_ptr(lrng_irq_pool);
+	struct lrng_drng *drng = lrng_drng_node_instance();
+	const struct lrng_hash_cb *hash_cb;
+	spinlock_t *lock = this_cpu_ptr(&lrng_irq_lock);
+	unsigned long flags, flags2;
+	void *hash;
+	bool init = false;
+
+	read_lock_irqsave(&drng->hash_lock, flags);
+	hash_cb = drng->hash_cb;
+	hash = drng->hash;
+
+	if (unlikely(!this_cpu_read(lrng_irq_lock_init))) {
+		init = true;
+		spin_lock_init(lock);
+		this_cpu_write(lrng_irq_lock_init, true);
+		pr_debug("Initializing per-CPU entropy pool for CPU %d on NUMA node %d with hash %s\n",
+			 raw_smp_processor_id(), numa_node_id(),
+			 hash_cb->hash_name());
+	}
+
+	spin_lock_irqsave(lock, flags2);
+
+	if (unlikely(init) && hash_cb->hash_init(shash, hash)) {
+		this_cpu_write(lrng_irq_lock_init, false);
+		pr_warn("Initialization of hash failed\n");
+	} else if (lrng_irq_continuous_compression) {
+		/* Add entire per-CPU data array content into entropy pool. */
+		if (hash_cb->hash_update(shash,
+					(u8 *)this_cpu_ptr(lrng_irq_array),
+					LRNG_DATA_ARRAY_SIZE * sizeof(u32)))
+			pr_warn_ratelimited("Hashing of entropy data failed\n");
+	}
+
+	spin_unlock_irqrestore(lock, flags2);
+	read_unlock_irqrestore(&drng->hash_lock, flags);
+}
+
+/* Compress data array into hash */
+static void lrng_irq_array_to_hash(u32 ptr)
+{
+	u32 *array = this_cpu_ptr(lrng_irq_array);
+
+	/*
+	 * During boot time the hash operation is triggered more often than
+	 * during regular operation.
+	 */
+	if (unlikely(!lrng_state_fully_seeded())) {
+		if ((ptr & 31) && (ptr < LRNG_DATA_WORD_MASK))
+			return;
+	} else if (ptr < LRNG_DATA_WORD_MASK) {
+		return;
+	}
+
+	if (lrng_raw_array_entropy_store(*array)) {
+		u32 i;
+
+		/*
+		 * If we fed even a part of the array to external analysis, we
+		 * mark that the entire array and the per-CPU pool to have no
+		 * entropy. This is due to the non-IID property of the data as
+		 * we do not fully know whether the existing dependencies
+		 * diminish the entropy beyond to what we expect it has.
+		 */
+		atomic_set(this_cpu_ptr(&lrng_irq_array_irqs), 0);
+
+		for (i = 1; i < LRNG_DATA_ARRAY_SIZE; i++)
+			lrng_raw_array_entropy_store(*(array + i));
+	} else {
+		lrng_irq_array_compress();
+		/* Ping pool handler about received entropy */
+		if (lrng_sp80090b_startup_complete_es(lrng_int_es_irq))
+			lrng_es_add_entropy();
+	}
+}
+
+/*
+ * Concatenate full 32 bit word at the end of time array even when current
+ * ptr is not aligned to sizeof(data).
+ */
+static void _lrng_irq_array_add_u32(u32 data)
+{
+	/* Increment pointer by number of slots taken for input value */
+	u32 pre_ptr, mask, ptr = this_cpu_add_return(lrng_irq_array_ptr,
+						     LRNG_DATA_SLOTS_PER_UINT);
+	unsigned int pre_array;
+
+	/*
+	 * This function injects a unit into the array - guarantee that
+	 * array unit size is equal to data type of input data.
+	 */
+	BUILD_BUG_ON(LRNG_DATA_ARRAY_MEMBER_BITS != (sizeof(data) << 3));
+
+	/*
+	 * The following logic requires at least two units holding
+	 * the data as otherwise the pointer would immediately wrap when
+	 * injection an u32 word.
+	 */
+	BUILD_BUG_ON(LRNG_DATA_NUM_VALUES <= LRNG_DATA_SLOTS_PER_UINT);
+
+	lrng_data_split_u32(&ptr, &pre_ptr, &mask);
+
+	/* MSB of data go into previous unit */
+	pre_array = lrng_data_idx2array(pre_ptr);
+	/* zeroization of slot to ensure the following OR adds the data */
+	this_cpu_and(lrng_irq_array[pre_array], ~(0xffffffff & ~mask));
+	this_cpu_or(lrng_irq_array[pre_array], data & ~mask);
+
+	/* Invoke compression as we just filled data array completely */
+	if (unlikely(pre_ptr > ptr))
+		lrng_irq_array_to_hash(LRNG_DATA_WORD_MASK);
+
+	/* LSB of data go into current unit */
+	this_cpu_write(lrng_irq_array[lrng_data_idx2array(ptr)],
+		       data & mask);
+
+	if (likely(pre_ptr <= ptr))
+		lrng_irq_array_to_hash(ptr);
+}
+
+/* Concatenate a 32-bit word at the end of the per-CPU array */
+void lrng_irq_array_add_u32(u32 data)
+{
+	/*
+	 * Disregard entropy-less data without continuous compression to
+	 * avoid it overwriting data with entropy when array ptr wraps.
+	 */
+	if (lrng_irq_continuous_compression)
+		_lrng_irq_array_add_u32(data);
+}
+
+/* Concatenate data of max LRNG_DATA_SLOTSIZE_MASK at the end of time array */
+static void lrng_irq_array_add_slot(u32 data)
+{
+	/* Get slot */
+	u32 ptr = this_cpu_inc_return(lrng_irq_array_ptr) &
+							LRNG_DATA_WORD_MASK;
+	unsigned int array = lrng_data_idx2array(ptr);
+	unsigned int slot = lrng_data_idx2slot(ptr);
+
+	BUILD_BUG_ON(LRNG_DATA_ARRAY_MEMBER_BITS % LRNG_DATA_SLOTSIZE_BITS);
+	/* Ensure consistency of values */
+	BUILD_BUG_ON(LRNG_DATA_ARRAY_MEMBER_BITS !=
+		     sizeof(lrng_irq_array[0]) << 3);
+
+	/* zeroization of slot to ensure the following OR adds the data */
+	this_cpu_and(lrng_irq_array[array],
+		     ~(lrng_data_slot_val(0xffffffff & LRNG_DATA_SLOTSIZE_MASK,
+					  slot)));
+	/* Store data into slot */
+	this_cpu_or(lrng_irq_array[array], lrng_data_slot_val(data, slot));
+
+	lrng_irq_array_to_hash(ptr);
+}
+
+static void
+lrng_time_process_common(u32 time, void(*add_time)(u32 data))
+{
+	enum lrng_health_res health_test;
+
+	if (lrng_raw_hires_entropy_store(time))
+		return;
+
+	health_test = lrng_health_test(time, lrng_int_es_irq);
+	if (health_test > lrng_health_fail_use)
+		return;
+
+	if (health_test == lrng_health_pass)
+		atomic_inc_return(this_cpu_ptr(&lrng_irq_array_irqs));
+
+	add_time(time);
+}
+
+/*
+ * Batching up of entropy in per-CPU array before injecting into entropy pool.
+ */
+static void lrng_time_process(void)
+{
+	u32 now_time = random_get_entropy();
+
+	if (unlikely(!lrng_gcd_tested())) {
+		/* When GCD is unknown, we process the full time stamp */
+		lrng_time_process_common(now_time, _lrng_irq_array_add_u32);
+		lrng_gcd_add_value(now_time);
+	} else {
+		/* GCD is known and applied */
+		lrng_time_process_common((now_time / lrng_gcd_get()) &
+					 LRNG_DATA_SLOTSIZE_MASK,
+					 lrng_irq_array_add_slot);
+	}
+
+	lrng_perf_time(now_time);
+}
+
+/* Hot code path - Callback for interrupt handler */
+void add_interrupt_randomness(int irq)
+{
+	if (lrng_highres_timer()) {
+		lrng_time_process();
+	} else {
+		struct pt_regs *regs = get_irq_regs();
+		static atomic_t reg_idx = ATOMIC_INIT(0);
+		u64 ip;
+		u32 tmp;
+
+		if (regs) {
+			u32 *ptr = (u32 *)regs;
+			int reg_ptr = atomic_add_return_relaxed(1, &reg_idx);
+			size_t n = (sizeof(struct pt_regs) / sizeof(u32));
+
+			ip = instruction_pointer(regs);
+			tmp = *(ptr + (reg_ptr % n));
+			tmp = lrng_raw_regs_entropy_store(tmp) ? 0 : tmp;
+			_lrng_irq_array_add_u32(tmp);
+		} else {
+			ip = _RET_IP_;
+		}
+
+		lrng_time_process();
+
+		/*
+		 * The XOR operation combining the different values is not
+		 * considered to destroy entropy since the entirety of all
+		 * processed values delivers the entropy (and not each
+		 * value separately of the other values).
+		 */
+		tmp = lrng_raw_jiffies_entropy_store(jiffies) ? 0 : jiffies;
+		tmp ^= lrng_raw_irq_entropy_store(irq) ? 0 : irq;
+		tmp ^= lrng_raw_retip_entropy_store(ip) ? 0 : ip;
+		tmp ^= ip >> 32;
+		_lrng_irq_array_add_u32(tmp);
+	}
+}
+EXPORT_SYMBOL(add_interrupt_randomness);
+
+static void lrng_irq_es_state(unsigned char *buf, size_t buflen)
+{
+	const struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+
+	/* Assume the lrng_drng_init lock is taken by caller */
+	snprintf(buf, buflen,
+		 " Hash for operating entropy pool: %s\n"
+		 " Available entropy: %u\n"
+		 " per-CPU interrupt collection size: %u\n"
+		 " Standards compliance: %s\n"
+		 " High-resolution timer: %s\n"
+		 " Continuous compression: %s\n"
+		 " Health test passed: %s\n",
+		 lrng_drng_init->hash_cb->hash_name(),
+		 lrng_irq_avail_entropy(0),
+		 LRNG_DATA_NUM_VALUES,
+		 lrng_sp80090b_compliant(lrng_int_es_irq) ? "SP800-90B " : "",
+		 lrng_highres_timer() ? "true" : "false",
+		 lrng_irq_continuous_compression ? "true" : "false",
+		 lrng_sp80090b_startup_complete_es(lrng_int_es_irq) ? "true" :
+								      "false");
+}
+
+struct lrng_es_cb lrng_es_irq = {
+	.name 			= "IRQ",
+	.get_ent		= lrng_irq_pool_hash,
+	.curr_entropy		= lrng_irq_avail_entropy,
+	.max_entropy		= lrng_irq_avail_pool_size,
+	.state			= lrng_irq_es_state,
+	.reset			= lrng_irq_reset,
+	.switch_hash		= lrng_irq_switch_hash,
+};
diff --git a/drivers/char/lrng/lrng_es_irq.h b/drivers/char/lrng/lrng_es_irq.h
new file mode 100644
index 000000000..2cd746611
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_irq.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_IRQ_H
+#define _LRNG_ES_IRQ_H
+
+#include <linux/lrng.h>
+
+#include "lrng_es_mgr_cb.h"
+
+#ifdef CONFIG_LRNG_IRQ
+void lrng_irq_es_init(bool highres_timer);
+void lrng_irq_array_add_u32(u32 data);
+
+extern struct lrng_es_cb lrng_es_irq;
+
+#else /* CONFIG_LRNG_IRQ */
+static inline void lrng_irq_es_init(bool highres_timer) { }
+static inline void lrng_irq_array_add_u32(u32 data) { }
+#endif /* CONFIG_LRNG_IRQ */
+
+#endif /* _LRNG_ES_IRQ_H */
diff --git a/drivers/char/lrng/lrng_es_jent.c b/drivers/char/lrng/lrng_es_jent.c
new file mode 100644
index 000000000..f74b7a03b
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_jent.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Fast Entropy Source: Jitter RNG
+ *
+ * Copyright (C) 2022 - 2023, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <crypto/rng.h>
+#include <linux/fips.h>
+#include <linux/module.h>
+#include <linux/types.h>
+
+#include "lrng_definitions.h"
+#include "lrng_es_aux.h"
+#include "lrng_es_jent.h"
+#include "lrng_es_mgr.h"
+
+/*
+ * Estimated entropy of data is a 16th of LRNG_DRNG_SECURITY_STRENGTH_BITS.
+ * Albeit a full entropy assessment is provided for the noise source indicating
+ * that it provides high entropy rates and considering that it deactivates
+ * when it detects insufficient hardware, the chosen under estimation of
+ * entropy is considered to be acceptable to all reviewers.
+ */
+static u32 jent_entropy = CONFIG_LRNG_JENT_ENTROPY_RATE;
+#ifdef CONFIG_LRNG_RUNTIME_ES_CONFIG
+module_param(jent_entropy, uint, 0644);
+MODULE_PARM_DESC(jent_entropy, "Entropy in bits of 256 data bits from Jitter RNG noise source");
+#endif
+
+static bool lrng_jent_initialized = false;
+static struct crypto_rng *jent;
+
+static int __init lrng_jent_initialize(void)
+{
+	jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
+	if (IS_ERR(jent)) {
+		pr_err("Cannot allocate Jitter RNG\n");
+		return PTR_ERR(jent);
+	}
+
+	lrng_jent_initialized = true;
+	pr_debug("Jitter RNG working on current system\n");
+
+	/*
+	 * In FIPS mode, the Jitter RNG is defined to have full of entropy
+	 * unless a different value has been specified at the command line
+	 * (i.e. the user overrides the default), and the default value is
+	 * larger than zero (if it is zero, it is assumed that an RBG2(P) or
+	 * RBG2(NP) construction is attempted that intends to exclude the
+	 * Jitter RNG).
+	 */
+	if (fips_enabled &&
+	    CONFIG_LRNG_JENT_ENTROPY_RATE > 0 &&
+	    jent_entropy == CONFIG_LRNG_JENT_ENTROPY_RATE)
+		jent_entropy = LRNG_DRNG_SECURITY_STRENGTH_BITS;
+
+	if (jent_entropy)
+		lrng_force_fully_seeded();
+
+	return 0;
+}
+device_initcall(lrng_jent_initialize);
+
+static u32 lrng_jent_entropylevel(u32 requested_bits)
+{
+	return lrng_fast_noise_entropylevel(lrng_jent_initialized ?
+					    jent_entropy : 0, requested_bits);
+}
+
+static u32 lrng_jent_poolsize(void)
+{
+	return lrng_jent_entropylevel(lrng_security_strength());
+}
+
+/*
+ * lrng_get_jent() - Get Jitter RNG entropy
+ *
+ * @eb: entropy buffer to store entropy
+ * @requested_bits: requested entropy in bits
+ */
+static void lrng_jent_get(struct entropy_buf *eb, u32 requested_bits,
+			  bool __unused)
+{
+	int ret;
+	u32 ent_bits = lrng_jent_entropylevel(requested_bits);
+	unsigned long flags;
+	static DEFINE_SPINLOCK(lrng_jent_lock);
+
+	spin_lock_irqsave(&lrng_jent_lock, flags);
+
+	if (!lrng_jent_initialized) {
+		spin_unlock_irqrestore(&lrng_jent_lock, flags);
+		goto err;
+	}
+
+	ret = crypto_rng_get_bytes(jent, eb->e[lrng_ext_es_jitter],
+				   requested_bits >> 3);
+
+	spin_unlock_irqrestore(&lrng_jent_lock, flags);
+
+	if (ret) {
+		pr_debug("Jitter RNG failed with %d\n", ret);
+		goto err;
+	}
+
+	pr_debug("obtained %u bits of entropy from Jitter RNG noise source\n",
+		 ent_bits);
+
+	eb->e_bits[lrng_ext_es_jitter] = ent_bits;
+	return;
+
+err:
+	eb->e_bits[lrng_ext_es_jitter] = 0;
+}
+
+static void lrng_jent_es_state(unsigned char *buf, size_t buflen)
+{
+	snprintf(buf, buflen,
+		 " Available entropy: %u\n"
+		 " Enabled: %s\n",
+		 lrng_jent_poolsize(),
+		 lrng_jent_initialized ? "true" : "false");
+}
+
+struct lrng_es_cb lrng_es_jent = {
+	.name			= "JitterRNG",
+	.get_ent		= lrng_jent_get,
+	.curr_entropy		= lrng_jent_entropylevel,
+	.max_entropy		= lrng_jent_poolsize,
+	.state			= lrng_jent_es_state,
+	.reset			= NULL,
+	.switch_hash		= NULL,
+};
diff --git a/drivers/char/lrng/lrng_es_jent.h b/drivers/char/lrng/lrng_es_jent.h
new file mode 100644
index 000000000..32882d4bd
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_jent.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_JENT_H
+#define _LRNG_ES_JENT_H
+
+#include "lrng_es_mgr_cb.h"
+
+#ifdef CONFIG_LRNG_JENT
+
+extern struct lrng_es_cb lrng_es_jent;
+
+#endif /* CONFIG_LRNG_JENT */
+
+#endif /* _LRNG_ES_JENT_H */
diff --git a/drivers/char/lrng/lrng_es_krng.c b/drivers/char/lrng/lrng_es_krng.c
new file mode 100644
index 000000000..519ba640c
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_krng.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Fast Entropy Source: Linux kernel RNG (random.c)
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/fips.h>
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/types.h>
+
+#include "lrng_es_aux.h"
+#include "lrng_es_krng.h"
+
+static u32 krng_entropy = CONFIG_LRNG_KERNEL_RNG_ENTROPY_RATE;
+#ifdef CONFIG_LRNG_RUNTIME_ES_CONFIG
+module_param(krng_entropy, uint, 0644);
+MODULE_PARM_DESC(krng_entropy, "Entropy in bits of 256 data bits from the kernel RNG noise source");
+#endif
+
+static atomic_t lrng_krng_initial_rate = ATOMIC_INIT(0);
+
+static u32 lrng_krng_fips_entropylevel(u32 entropylevel)
+{
+	return fips_enabled ? 0 : entropylevel;
+}
+
+static int lrng_krng_adjust_entropy(void)
+{
+	u32 entropylevel;
+
+	krng_entropy = atomic_read_u32(&lrng_krng_initial_rate);
+
+	entropylevel = lrng_krng_fips_entropylevel(krng_entropy);
+	pr_debug("Kernel RNG is fully seeded, setting entropy rate to %u bits of entropy\n",
+		 entropylevel);
+	lrng_drng_force_reseed();
+	if (entropylevel)
+		lrng_es_add_entropy();
+	return 0;
+}
+
+static u32 lrng_krng_entropylevel(u32 requested_bits)
+{
+	static bool init = false;
+
+	if (unlikely(!init) && rng_is_initialized()) {
+		init = true;
+		lrng_krng_adjust_entropy();
+	}
+
+	return lrng_fast_noise_entropylevel(
+		lrng_krng_fips_entropylevel(krng_entropy), requested_bits);
+}
+
+static u32 lrng_krng_poolsize(void)
+{
+	return lrng_krng_entropylevel(lrng_security_strength());
+}
+
+/*
+ * lrng_krng_get() - Get kernel RNG entropy
+ *
+ * @eb: entropy buffer to store entropy
+ * @requested_bits: requested entropy in bits
+ */
+static void lrng_krng_get(struct entropy_buf *eb, u32 requested_bits,
+			  bool __unused)
+{
+	u32 ent_bits = lrng_krng_entropylevel(requested_bits);
+
+	get_random_bytes(eb->e[lrng_ext_es_krng], requested_bits >> 3);
+
+	pr_debug("obtained %u bits of entropy from kernel RNG noise source\n",
+		 ent_bits);
+
+	eb->e_bits[lrng_ext_es_krng] = ent_bits;
+}
+
+static void lrng_krng_es_state(unsigned char *buf, size_t buflen)
+{
+	snprintf(buf, buflen,
+		 " Available entropy: %u\n"
+		 " Entropy Rate per 256 data bits: %u\n",
+		 lrng_krng_poolsize(),
+		 lrng_krng_entropylevel(256));
+}
+
+struct lrng_es_cb lrng_es_krng = {
+	.name			= "KernelRNG",
+	.get_ent		= lrng_krng_get,
+	.curr_entropy		= lrng_krng_entropylevel,
+	.max_entropy		= lrng_krng_poolsize,
+	.state			= lrng_krng_es_state,
+	.reset			= NULL,
+	.switch_hash		= NULL,
+};
diff --git a/drivers/char/lrng/lrng_es_krng.h b/drivers/char/lrng/lrng_es_krng.h
new file mode 100644
index 000000000..cf982b9ee
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_krng.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_RANDOM_H
+#define _LRNG_ES_RANDOM_H
+
+#include "lrng_es_mgr_cb.h"
+
+#ifdef CONFIG_LRNG_KERNEL_RNG
+
+extern struct lrng_es_cb lrng_es_krng;
+
+#endif /* CONFIG_LRNG_KERNEL_RNG */
+
+#endif /* _LRNG_ES_RANDOM_H */
diff --git a/drivers/char/lrng/lrng_es_mgr.c b/drivers/char/lrng/lrng_es_mgr.c
new file mode 100644
index 000000000..9570a4a1b
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_mgr.c
@@ -0,0 +1,506 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Entropy sources management
+ *
+ * Copyright (C) 2022 - 2023, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/random.h>
+#include <linux/utsname.h>
+#include <linux/workqueue.h>
+#include <asm/archrandom.h>
+
+#include "lrng_drng_atomic.h"
+#include "lrng_drng_mgr.h"
+#include "lrng_es_aux.h"
+#include "lrng_es_cpu.h"
+#include "lrng_es_irq.h"
+#include "lrng_es_jent.h"
+#include "lrng_es_krng.h"
+#include "lrng_es_mgr.h"
+#include "lrng_es_sched.h"
+#include "lrng_interface_dev_common.h"
+#include "lrng_interface_random_kernel.h"
+
+struct lrng_state {
+	bool can_invalidate;		/* Can invalidate batched entropy? */
+	bool perform_seedwork;		/* Can seed work be performed? */
+	bool lrng_operational;		/* Is DRNG operational? */
+	bool lrng_fully_seeded;		/* Is DRNG fully seeded? */
+	bool lrng_min_seeded;		/* Is DRNG minimally seeded? */
+	bool all_online_numa_node_seeded;/* All NUMA DRNGs seeded? */
+
+	/*
+	 * To ensure that external entropy providers cannot dominate the
+	 * internal noise sources but yet cannot be dominated by internal
+	 * noise sources, the following booleans are intended to allow
+	 * external to provide seed once when a DRNG reseed occurs. This
+	 * triggering of external noise source is performed even when the
+	 * entropy pool has sufficient entropy.
+	 */
+
+	atomic_t boot_entropy_thresh;	/* Reseed threshold */
+	struct mutex reseed_in_progress;	/* Flag for on executing reseed */
+	struct work_struct lrng_seed_work;	/* (re)seed work queue */
+};
+
+static struct lrng_state lrng_state = {
+	false, false, false, false, false, false,
+	.boot_entropy_thresh	= ATOMIC_INIT(LRNG_INIT_ENTROPY_BITS),
+	.reseed_in_progress	=
+		__MUTEX_INITIALIZER(lrng_state.reseed_in_progress),
+};
+
+/*
+ * If the entropy count falls under this number of bits, then we
+ * should wake up processes which are selecting or polling on write
+ * access to /dev/random.
+ */
+u32 lrng_write_wakeup_bits = (LRNG_WRITE_WAKEUP_ENTROPY << 3);
+
+/*
+ * The entries must be in the same order as defined by enum lrng_internal_es and
+ * enum lrng_external_es
+ */
+struct lrng_es_cb *lrng_es[] = {
+#ifdef CONFIG_LRNG_IRQ
+	&lrng_es_irq,
+#endif
+#ifdef CONFIG_LRNG_SCHED
+	&lrng_es_sched,
+#endif
+#ifdef CONFIG_LRNG_JENT
+	&lrng_es_jent,
+#endif
+#ifdef CONFIG_LRNG_CPU
+	&lrng_es_cpu,
+#endif
+#ifdef CONFIG_LRNG_KERNEL_RNG
+	&lrng_es_krng,
+#endif
+	&lrng_es_aux
+};
+
+static bool ntg1 = false;
+#ifdef CONFIG_LRNG_AIS2031_NTG1_SEEDING_STRATEGY
+module_param(ntg1, bool, 0444);
+MODULE_PARM_DESC(ntg1, "Enable AIS20/31 NTG.1 compliant seeding strategy\n");
+#endif
+
+/* Only panic the kernel on permanent health failure if this variable is true */
+static bool lrng_panic_on_permanent_health_failure = false;
+module_param(lrng_panic_on_permanent_health_failure, bool, 0444);
+MODULE_PARM_DESC(lrng_panic_on_permanent_health_failure, "Panic on reaching permanent health failure - only required if LRNG is part of a FIPS 140-3 module\n");
+
+/********************************** Helper ***********************************/
+
+bool lrng_enforce_panic_on_permanent_health_failure(void)
+{
+	return lrng_panic_on_permanent_health_failure;
+}
+
+bool lrng_ntg1_2022_compliant(void)
+{
+	/* Implies use of /dev/random w/ O_SYNC / getrandom w/ GRND_RANDOM */
+	return ntg1;
+}
+
+void lrng_debug_report_seedlevel(const char *name)
+{
+#ifdef CONFIG_WARN_ALL_UNSEEDED_RANDOM
+	static void *previous = NULL;
+	void *caller = (void *) _RET_IP_;
+	struct lrng_drng *atomic = lrng_get_atomic();
+
+	if (READ_ONCE(previous) == caller)
+		return;
+
+	if (atomic && !atomic->fully_seeded)
+		pr_notice("%pS %s called without reaching minimally seeded level (available entropy %u)\n",
+			  caller, name, lrng_avail_entropy());
+
+	WRITE_ONCE(previous, caller);
+#endif
+}
+
+/*
+ * Reading of the LRNG pool is only allowed by one caller. The reading is
+ * only performed to (re)seed DRNGs. Thus, if this "lock" is already taken,
+ * the reseeding operation is in progress. The caller is not intended to wait
+ * but continue with its other operation.
+ */
+int lrng_pool_trylock(void)
+{
+	return mutex_trylock(&lrng_state.reseed_in_progress);
+}
+
+void lrng_pool_lock(void)
+{
+	mutex_lock(&lrng_state.reseed_in_progress);
+}
+
+void lrng_pool_unlock(void)
+{
+	mutex_unlock(&lrng_state.reseed_in_progress);
+}
+
+/* Set new entropy threshold for reseeding during boot */
+void lrng_set_entropy_thresh(u32 new_entropy_bits)
+{
+	atomic_set(&lrng_state.boot_entropy_thresh, new_entropy_bits);
+}
+
+/*
+ * Reset LRNG state - the entropy counters are reset, but the data that may
+ * or may not have entropy remains in the pools as this data will not hurt.
+ */
+void lrng_reset_state(void)
+{
+	u32 i;
+
+	for_each_lrng_es(i) {
+		if (lrng_es[i]->reset)
+			lrng_es[i]->reset();
+	}
+	lrng_state.lrng_operational = false;
+	lrng_state.lrng_fully_seeded = false;
+	lrng_state.lrng_min_seeded = false;
+	lrng_state.all_online_numa_node_seeded = false;
+	pr_debug("reset LRNG\n");
+}
+
+/* Set flag that all DRNGs are fully seeded */
+void lrng_pool_all_numa_nodes_seeded(bool set)
+{
+	lrng_state.all_online_numa_node_seeded = set;
+	if (set)
+		wake_up_all(&lrng_init_wait);
+}
+
+bool lrng_pool_all_numa_nodes_seeded_get(void)
+{
+	return lrng_state.all_online_numa_node_seeded;
+}
+
+/* Return boolean whether LRNG reached minimally seed level */
+bool lrng_state_min_seeded(void)
+{
+	return lrng_state.lrng_min_seeded;
+}
+
+/* Return boolean whether LRNG reached fully seed level */
+bool lrng_state_fully_seeded(void)
+{
+	return lrng_state.lrng_fully_seeded;
+}
+
+/* Return boolean whether LRNG is considered fully operational */
+bool lrng_state_operational(void)
+{
+	return lrng_state.lrng_operational;
+}
+
+static void lrng_init_wakeup(void)
+{
+	wake_up_all(&lrng_init_wait);
+	lrng_init_wakeup_dev();
+	lrng_kick_random_ready();
+}
+
+static u32 lrng_avail_entropy_thresh(void)
+{
+	u32 ent_thresh = lrng_security_strength();
+
+	/*
+	 * Apply oversampling during initialization according to SP800-90C as
+	 * we request a larger buffer from the ES.
+	 */
+	if (lrng_sp80090c_compliant() &&
+	    !lrng_state.all_online_numa_node_seeded)
+		ent_thresh += LRNG_SEED_BUFFER_INIT_ADD_BITS;
+
+	return ent_thresh;
+}
+
+bool lrng_fully_seeded(bool fully_seeded, u32 collected_entropy,
+		       struct entropy_buf *eb)
+{
+	/* AIS20/31 NTG.1: two entropy sources with each delivering 220 bits */
+	if (ntg1) {
+		u32 i, result = 0, ent_thresh = lrng_avail_entropy_thresh();
+
+		for_each_lrng_es(i) {
+			result += (eb ? eb->e_bits[i] :
+				        lrng_es[i]->curr_entropy(ent_thresh)) >=
+				  LRNG_AIS2031_NPTRNG_MIN_ENTROPY;
+		}
+
+		return (result >= 2);
+	}
+
+	return (collected_entropy >= lrng_get_seed_entropy_osr(fully_seeded));
+}
+
+u32 lrng_entropy_rate_eb(struct entropy_buf *eb)
+{
+	u32 i, collected_entropy = 0;
+
+	for_each_lrng_es(i)
+		collected_entropy += eb->e_bits[i];
+
+	return collected_entropy;
+}
+
+/* Mark one DRNG as not fully seeded */
+void lrng_unset_fully_seeded(struct lrng_drng *drng)
+{
+	drng->fully_seeded = false;
+	lrng_pool_all_numa_nodes_seeded(false);
+
+	/*
+	 * The init DRNG instance must always be fully seeded as this instance
+	 * is the fall-back if any of the per-NUMA node DRNG instances is
+	 * insufficiently seeded. Thus, we mark the entire LRNG as
+	 * non-operational if the initial DRNG becomes not fully seeded.
+	 */
+	if (drng == lrng_drng_init_instance() && lrng_state_operational()) {
+		pr_debug("LRNG set to non-operational\n");
+		lrng_state.lrng_operational = false;
+		lrng_state.lrng_fully_seeded = false;
+
+		/* If sufficient entropy is available, reseed now. */
+		lrng_es_add_entropy();
+	}
+}
+
+/* Policy to enable LRNG operational mode */
+static void lrng_set_operational(void)
+{
+	/*
+	 * LRNG is operational if the initial DRNG is fully seeded. This state
+	 * can only occur if either the external entropy sources provided
+	 * sufficient entropy, or the SP800-90B startup test completed for
+	 * the internal ES to supply also entropy data.
+	 */
+	if (lrng_state.lrng_fully_seeded) {
+		lrng_state.lrng_operational = true;
+		lrng_init_wakeup();
+		pr_info("LRNG fully operational\n");
+	}
+}
+
+/* Available entropy in the entire LRNG considering all entropy sources */
+u32 lrng_avail_entropy(void)
+{
+	u32 i, ent = 0, ent_thresh = lrng_avail_entropy_thresh();
+
+	BUILD_BUG_ON(ARRAY_SIZE(lrng_es) != lrng_ext_es_last);
+	for_each_lrng_es(i)
+		ent += lrng_es[i]->curr_entropy(ent_thresh);
+	return ent;
+}
+
+u32 lrng_avail_entropy_aux(void)
+{
+	u32 ent_thresh = lrng_avail_entropy_thresh();
+
+	return lrng_es[lrng_ext_es_aux]->curr_entropy(ent_thresh);
+}
+
+/*
+ * lrng_init_ops() - Set seed stages of LRNG
+ *
+ * Set the slow noise source reseed trigger threshold. The initial threshold
+ * is set to the minimum data size that can be read from the pool: a word. Upon
+ * reaching this value, the next seed threshold of 128 bits is set followed
+ * by 256 bits.
+ *
+ * @eb: buffer containing the size of entropy currently injected into DRNG - if
+ *	NULL, the function obtains the available entropy from the ES.
+ */
+void lrng_init_ops(struct entropy_buf *eb)
+{
+	struct lrng_state *state = &lrng_state;
+	u32 i, requested_bits, seed_bits = 0;
+
+	if (state->lrng_operational)
+		return;
+
+	requested_bits = ntg1 ?
+		/* Approximation so that two ES should deliver 220 bits each */
+		(lrng_avail_entropy() + LRNG_AIS2031_NPTRNG_MIN_ENTROPY) :
+		/* Apply SP800-90C oversampling if applicable */
+		lrng_get_seed_entropy_osr(state->all_online_numa_node_seeded);
+
+	if (eb) {
+		seed_bits = lrng_entropy_rate_eb(eb);
+	} else {
+		u32 ent_thresh = lrng_avail_entropy_thresh();
+
+		for_each_lrng_es(i)
+			seed_bits += lrng_es[i]->curr_entropy(ent_thresh);
+	}
+
+	/* DRNG is seeded with full security strength */
+	if (state->lrng_fully_seeded) {
+		lrng_set_operational();
+		lrng_set_entropy_thresh(requested_bits);
+	} else if (lrng_fully_seeded(state->all_online_numa_node_seeded,
+				     seed_bits, eb)) {
+		if (state->can_invalidate)
+			invalidate_batched_entropy();
+
+		state->lrng_fully_seeded = true;
+		lrng_set_operational();
+		state->lrng_min_seeded = true;
+		pr_info("LRNG fully seeded with %u bits of entropy\n",
+			seed_bits);
+		lrng_set_entropy_thresh(requested_bits);
+	} else if (!state->lrng_min_seeded) {
+
+		/* DRNG is seeded with at least 128 bits of entropy */
+		if (seed_bits >= LRNG_MIN_SEED_ENTROPY_BITS) {
+			if (state->can_invalidate)
+				invalidate_batched_entropy();
+
+			state->lrng_min_seeded = true;
+			pr_info("LRNG minimally seeded with %u bits of entropy\n",
+				seed_bits);
+			lrng_set_entropy_thresh(requested_bits);
+			lrng_init_wakeup();
+
+		/* DRNG is seeded with at least LRNG_INIT_ENTROPY_BITS bits */
+		} else if (seed_bits >= LRNG_INIT_ENTROPY_BITS) {
+			pr_info("LRNG initial entropy level %u bits of entropy\n",
+				seed_bits);
+			lrng_set_entropy_thresh(LRNG_MIN_SEED_ENTROPY_BITS);
+		}
+	}
+}
+
+void __init lrng_rand_initialize_early(void)
+{
+	struct seed {
+		unsigned long data[((LRNG_MAX_DIGESTSIZE +
+				     sizeof(unsigned long) - 1) /
+				    sizeof(unsigned long))];
+		struct new_utsname utsname;
+	} seed __aligned(LRNG_KCAPI_ALIGN);
+	size_t longs = 0;
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(seed.data); i += longs) {
+		longs = arch_get_random_seed_longs(seed.data + i,
+						   ARRAY_SIZE(seed.data) - i);
+		if (longs)
+			continue;
+		longs = arch_get_random_longs(seed.data + i,
+					      ARRAY_SIZE(seed.data) - i);
+		if (longs)
+			continue;
+		longs = 1;
+	}
+	memcpy(&seed.utsname, init_utsname(), sizeof(*(init_utsname())));
+
+	lrng_pool_insert_aux((u8 *)&seed, sizeof(seed), 0);
+	memzero_explicit(&seed, sizeof(seed));
+
+	lrng_force_fully_seeded();
+}
+
+void __init lrng_rand_initialize(void)
+{
+	unsigned long entropy = random_get_entropy();
+	ktime_t time = ktime_get_real();
+
+	lrng_pool_insert_aux((u8 *)&entropy, sizeof(entropy), 0);
+	lrng_pool_insert_aux((u8 *)&time, sizeof(time), 0);
+
+	/* Initialize the seed work queue */
+	INIT_WORK(&lrng_state.lrng_seed_work, lrng_drng_seed_work);
+	lrng_state.perform_seedwork = true;
+
+	invalidate_batched_entropy();
+
+	lrng_state.can_invalidate = true;
+}
+
+#ifndef CONFIG_LRNG_RANDOM_IF
+static int __init lrng_rand_initialize_call(void)
+{
+	lrng_rand_initialize_early();
+	lrng_rand_initialize();
+	return 0;
+}
+
+early_initcall(lrng_rand_initialize_call);
+#endif
+
+/* Interface requesting a reseed of the DRNG */
+void lrng_es_add_entropy(void)
+{
+	/*
+	 * Once all DRNGs are fully seeded, the system-triggered arrival of
+	 * entropy will not cause any reseeding any more.
+	 */
+	if (likely(lrng_state.all_online_numa_node_seeded))
+		return;
+
+	/* Only trigger the DRNG reseed if we have collected entropy. */
+	if (lrng_avail_entropy() <
+	    atomic_read_u32(&lrng_state.boot_entropy_thresh))
+		return;
+
+	/* Ensure that the seeding only occurs once at any given time. */
+	if (!lrng_pool_trylock())
+		return;
+
+	/* Seed the DRNG with any available noise. */
+	if (lrng_state.perform_seedwork)
+		schedule_work(&lrng_state.lrng_seed_work);
+	else
+		lrng_drng_seed_work(NULL);
+}
+
+/* Fill the seed buffer with data from the noise sources */
+void lrng_fill_seed_buffer(struct entropy_buf *eb, u32 requested_bits,
+			   bool force)
+{
+	struct lrng_state *state = &lrng_state;
+	u32 i, req_ent = lrng_sp80090c_compliant() ?
+			  lrng_security_strength() : LRNG_MIN_SEED_ENTROPY_BITS;
+
+	/* Guarantee that requested bits is a multiple of bytes */
+	BUILD_BUG_ON(LRNG_DRNG_SECURITY_STRENGTH_BITS % 8);
+
+	/* always reseed the DRNG with the current time stamp */
+	eb->now = random_get_entropy();
+
+	/*
+	 * Require at least 128 bits of entropy for any reseed. If the LRNG is
+	 * operated SP800-90C compliant we want to comply with SP800-90A section
+	 * 9.2 mandating that DRNG is reseeded with the security strength.
+	 */
+	if (!force &&
+	    state->lrng_fully_seeded && (lrng_avail_entropy() < req_ent)) {
+		for_each_lrng_es(i)
+			eb->e_bits[i] = 0;
+
+		goto wakeup;
+	}
+
+	/* Concatenate the output of the entropy sources. */
+	for_each_lrng_es(i) {
+		lrng_es[i]->get_ent(eb, requested_bits,
+				    state->lrng_fully_seeded);
+	}
+
+	/* allow external entropy provider to provide seed */
+	lrng_state_exseed_allow_all();
+
+wakeup:
+	lrng_writer_wakeup();
+}
diff --git a/drivers/char/lrng/lrng_es_mgr.h b/drivers/char/lrng/lrng_es_mgr.h
new file mode 100644
index 000000000..7c4fbcb59
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_mgr.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_MGR_H
+#define _LRNG_ES_MGR_H
+
+#include "lrng_es_mgr_cb.h"
+
+/*************************** General LRNG parameter ***************************/
+
+#define LRNG_DRNG_BLOCKSIZE 64		/* Maximum of DRNG block sizes */
+
+/* Helper to concatenate a macro with an integer type */
+#define LRNG_PASTER(x, y) x ## y
+#define LRNG_UINT32_C(x) LRNG_PASTER(x, U)
+
+/************************* Entropy sources management *************************/
+
+extern struct lrng_es_cb *lrng_es[];
+
+#define for_each_lrng_es(ctr)		\
+	for ((ctr) = 0; (ctr) < lrng_ext_es_last; (ctr)++)
+
+bool lrng_enforce_panic_on_permanent_health_failure(void);
+bool lrng_ntg1_2022_compliant(void);
+bool lrng_pool_all_numa_nodes_seeded_get(void);
+bool lrng_state_min_seeded(void);
+void lrng_debug_report_seedlevel(const char *name);
+void lrng_rand_initialize_early(void);
+void lrng_rand_initialize(void);
+bool lrng_state_operational(void);
+
+extern u32 lrng_write_wakeup_bits;
+void lrng_set_entropy_thresh(u32 new);
+u32 lrng_avail_entropy(void);
+u32 lrng_avail_entropy_aux(void);
+void lrng_reset_state(void);
+
+bool lrng_state_fully_seeded(void);
+
+int lrng_pool_trylock(void);
+void lrng_pool_lock(void);
+void lrng_pool_unlock(void);
+void lrng_pool_all_numa_nodes_seeded(bool set);
+
+bool lrng_fully_seeded(bool fully_seeded, u32 collected_entropy,
+		       struct entropy_buf *eb);
+u32 lrng_entropy_rate_eb(struct entropy_buf *eb);
+void lrng_unset_fully_seeded(struct lrng_drng *drng);
+void lrng_fill_seed_buffer(struct entropy_buf *eb, u32 requested_bits,
+			   bool force);
+void lrng_init_ops(struct entropy_buf *eb);
+
+#endif /* _LRNG_ES_MGR_H */
diff --git a/drivers/char/lrng/lrng_es_mgr_cb.h b/drivers/char/lrng/lrng_es_mgr_cb.h
new file mode 100644
index 000000000..08b24e1b7
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_mgr_cb.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ *
+ * Definition of an entropy source.
+ */
+
+#ifndef _LRNG_ES_MGR_CB_H
+#define _LRNG_ES_MGR_CB_H
+
+#include <linux/lrng.h>
+
+#include "lrng_definitions.h"
+#include "lrng_drng_mgr.h"
+
+enum lrng_internal_es {
+#ifdef CONFIG_LRNG_IRQ
+	lrng_int_es_irq,			/* IRQ-based entropy source */
+#endif
+#ifdef CONFIG_LRNG_SCHED
+	lrng_int_es_sched,			/* Scheduler entropy source */
+#endif
+	lrng_int_es_last,			/* MUST be the last entry */
+};
+
+enum lrng_external_es {
+	lrng_ext_link = lrng_int_es_last - 1,	/* Link entry */
+#ifdef CONFIG_LRNG_JENT
+	lrng_ext_es_jitter,			/* Jitter RNG */
+#endif
+#ifdef CONFIG_LRNG_CPU
+	lrng_ext_es_cpu,			/* CPU-based, e.g. RDSEED */
+#endif
+#ifdef CONFIG_LRNG_KERNEL_RNG
+	lrng_ext_es_krng,			/* random.c */
+#endif
+	lrng_ext_es_aux,			/* MUST BE LAST ES! */
+	lrng_ext_es_last			/* MUST be the last entry */
+};
+
+struct entropy_buf {
+	u8 e[lrng_ext_es_last][LRNG_DRNG_INIT_SEED_SIZE_BYTES];
+	u32 now, e_bits[lrng_ext_es_last];
+};
+
+/*
+ * struct lrng_es_cb - callback defining an entropy source
+ * @name: Name of the entropy source.
+ * @get_ent: Fetch entropy into the entropy_buf. The ES shall only deliver
+ *	     data if its internal initialization is complete, including any
+ *	     SP800-90B startup testing or similar.
+ * @curr_entropy: Return amount of currently available entropy.
+ * @max_entropy: Maximum amount of entropy the entropy source is able to
+ *		 maintain.
+ * @state: Buffer with human-readable ES state.
+ * @reset: Reset entropy source (drop all entropy and reinitialize).
+ *	   This callback may be NULL.
+ * @switch_hash: callback to switch from an old hash callback definition to
+ *		 a new one. This callback may be NULL.
+ */
+struct lrng_es_cb {
+	const char *name;
+	void (*get_ent)(struct entropy_buf *eb, u32 requested_bits,
+			bool fully_seeded);
+	u32 (*curr_entropy)(u32 requested_bits);
+	u32 (*max_entropy)(void);
+	void (*state)(unsigned char *buf, size_t buflen);
+	void (*reset)(void);
+	int (*switch_hash)(struct lrng_drng *drng, int node,
+			   const struct lrng_hash_cb *new_cb, void *new_hash,
+			   const struct lrng_hash_cb *old_cb);
+};
+
+/* Allow entropy sources to tell the ES manager that new entropy is there */
+void lrng_es_add_entropy(void);
+
+/* Cap to maximum entropy that can ever be generated with given hash */
+#define lrng_cap_requested(__digestsize_bits, __requested_bits)		\
+	do {								\
+		if (__digestsize_bits < __requested_bits) {		\
+			pr_debug("Cannot satisfy requested entropy %u due to insufficient hash size %u\n",\
+				 __requested_bits, __digestsize_bits);	\
+			__requested_bits = __digestsize_bits;		\
+		}							\
+	} while (0)
+
+#endif /* _LRNG_ES_MGR_CB_H */
diff --git a/drivers/char/lrng/lrng_es_sched.c b/drivers/char/lrng/lrng_es_sched.c
new file mode 100644
index 000000000..333c5b1ff
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_sched.c
@@ -0,0 +1,566 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Slow Entropy Source: Scheduler-based data collection
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <asm/irq_regs.h>
+#include <asm/ptrace.h>
+#include <linux/lrng.h>
+#include <crypto/hash.h>
+#include <linux/module.h>
+#include <linux/random.h>
+
+#include "lrng_es_aux.h"
+#include "lrng_es_sched.h"
+#include "lrng_es_timer_common.h"
+#include "lrng_health.h"
+#include "lrng_numa.h"
+#include "lrng_testing.h"
+
+/*
+ * Number of scheduler-based context switches to be recorded to assume that
+ * DRNG security strength bits of entropy are received.
+ * Note: a value below the DRNG security strength should not be defined as this
+ *	 may imply the DRNG can never be fully seeded in case other noise
+ *	 sources are unavailable.
+ */
+#define LRNG_SCHED_ENTROPY_BITS	\
+	LRNG_UINT32_C(CONFIG_LRNG_SCHED_ENTROPY_RATE)
+
+/* Number of events required for LRNG_DRNG_SECURITY_STRENGTH_BITS entropy */
+static u32 lrng_sched_entropy_bits = LRNG_SCHED_ENTROPY_BITS;
+
+static u32 sched_entropy __read_mostly = LRNG_SCHED_ENTROPY_BITS;
+#ifdef CONFIG_LRNG_RUNTIME_ES_CONFIG
+module_param(sched_entropy, uint, 0444);
+MODULE_PARM_DESC(sched_entropy,
+		 "How many scheduler-based context switches must be collected for obtaining 256 bits of entropy\n");
+#endif
+
+/* Per-CPU array holding concatenated entropy events */
+static DEFINE_PER_CPU(u32 [LRNG_DATA_ARRAY_SIZE], lrng_sched_array)
+						__aligned(LRNG_KCAPI_ALIGN);
+static DEFINE_PER_CPU(u32, lrng_sched_array_ptr) = 0;
+static DEFINE_PER_CPU(atomic_t, lrng_sched_array_events) = ATOMIC_INIT(0);
+
+/*
+ * Per-CPU entropy pool with compressed entropy event
+ *
+ * The per-CPU entropy pool is defined as the hash state. New data is simply
+ * inserted into the entropy pool by performing a hash update operation.
+ * To read the entropy pool, a hash final must be invoked. However, before
+ * the entropy pool is released again after a hash final, the hash init must
+ * be performed.
+ */
+static DEFINE_PER_CPU(u8 [LRNG_POOL_SIZE], lrng_sched_pool)
+						__aligned(LRNG_KCAPI_ALIGN);
+/*
+ * Lock to allow other CPUs to read the pool - as this is only done during
+ * reseed which is infrequent, this lock is hardly contended.
+ */
+static DEFINE_PER_CPU(spinlock_t, lrng_sched_lock);
+static DEFINE_PER_CPU(bool, lrng_sched_lock_init) = false;
+
+static bool lrng_sched_pool_online(int cpu)
+{
+	return per_cpu(lrng_sched_lock_init, cpu);
+}
+
+static void __init lrng_sched_check_compression_state(void)
+{
+	/* One pool should hold sufficient entropy for disabled compression */
+	u32 max_ent = min_t(u32, lrng_get_digestsize(),
+			    lrng_data_to_entropy(LRNG_DATA_NUM_VALUES,
+						 lrng_sched_entropy_bits));
+	if (max_ent < lrng_security_strength()) {
+		pr_devel("Scheduler entropy source will never provide %u bits of entropy required for fully seeding the DRNG all by itself\n",
+			lrng_security_strength());
+	}
+}
+
+void __init lrng_sched_es_init(bool highres_timer)
+{
+	/* Set a minimum number of scheduler events that must be collected */
+	sched_entropy = max_t(u32, LRNG_SCHED_ENTROPY_BITS, sched_entropy);
+
+	if (highres_timer) {
+		lrng_sched_entropy_bits = sched_entropy;
+	} else {
+		u32 new_entropy = sched_entropy * LRNG_ES_OVERSAMPLING_FACTOR;
+
+		lrng_sched_entropy_bits = (sched_entropy < new_entropy) ?
+					  new_entropy : sched_entropy;
+		pr_warn("operating without high-resolution timer and applying oversampling factor %u\n",
+			LRNG_ES_OVERSAMPLING_FACTOR);
+	}
+
+	lrng_sched_check_compression_state();
+}
+
+static u32 lrng_sched_avail_pool_size(void)
+{
+	u32 max_pool = lrng_get_digestsize(),
+	    max_size = min_t(u32, max_pool, LRNG_DATA_NUM_VALUES);
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		max_size += max_pool;
+
+	return max_size;
+}
+
+/* Return entropy of unused scheduler events present in all per-CPU pools. */
+static u32 lrng_sched_avail_entropy(u32 __unused)
+{
+	u32 digestsize_events, events = 0;
+	int cpu;
+
+	/* Only deliver entropy when SP800-90B self test is completed */
+	if (!lrng_sp80090b_startup_complete_es(lrng_int_es_sched))
+		return 0;
+
+	/* Obtain the cap of maximum numbers of scheduler events we count */
+	digestsize_events = lrng_entropy_to_data(lrng_get_digestsize(),
+						 lrng_sched_entropy_bits);
+	/* Cap to max. number of scheduler events the array can hold */
+	digestsize_events = min_t(u32, digestsize_events, LRNG_DATA_NUM_VALUES);
+
+	for_each_online_cpu(cpu) {
+		events += min_t(u32, digestsize_events,
+			atomic_read_u32(per_cpu_ptr(&lrng_sched_array_events,
+					cpu)));
+	}
+
+	/* Consider oversampling rate */
+	return lrng_reduce_by_osr(
+			lrng_data_to_entropy(events, lrng_sched_entropy_bits));
+}
+
+/*
+ * Reset all per-CPU pools - reset entropy estimator but leave the pool data
+ * that may or may not have entropy unchanged.
+ */
+static void lrng_sched_reset(void)
+{
+	int cpu;
+
+	/* Trigger GCD calculation anew. */
+	lrng_gcd_set(0);
+
+	for_each_online_cpu(cpu)
+		atomic_set(per_cpu_ptr(&lrng_sched_array_events, cpu), 0);
+}
+
+/*
+ * Trigger a switch of the hash implementation for the per-CPU pool.
+ *
+ * For each per-CPU pool, obtain the message digest with the old hash
+ * implementation, initialize the per-CPU pool again with the new hash
+ * implementation and inject the message digest into the new state.
+ *
+ * Assumption: the caller must guarantee that the new_cb is available during the
+ * entire operation (e.g. it must hold the lock against pointer updating).
+ */
+static int
+lrng_sched_switch_hash(struct lrng_drng *drng, int node,
+		       const struct lrng_hash_cb *new_cb, void *new_hash,
+		       const struct lrng_hash_cb *old_cb)
+{
+	u8 digest[LRNG_MAX_DIGESTSIZE];
+	u32 digestsize_events, found_events;
+	int ret = 0, cpu;
+
+	if (!IS_ENABLED(CONFIG_LRNG_SWITCH))
+		return -EOPNOTSUPP;
+
+	for_each_online_cpu(cpu) {
+		struct shash_desc *pcpu_shash;
+
+		/*
+		 * Only switch the per-CPU pools for the current node because
+		 * the hash_cb only applies NUMA-node-wide.
+		 */
+		if (cpu_to_node(cpu) != node || !lrng_sched_pool_online(cpu))
+			continue;
+
+		pcpu_shash = (struct shash_desc *)per_cpu_ptr(lrng_sched_pool,
+							      cpu);
+
+		digestsize_events = old_cb->hash_digestsize(pcpu_shash);
+		digestsize_events = lrng_entropy_to_data(digestsize_events << 3,
+						       lrng_sched_entropy_bits);
+
+		if (pcpu_shash->tfm == new_hash)
+			continue;
+
+		/* Get the per-CPU pool hash with old digest ... */
+		ret = old_cb->hash_final(pcpu_shash, digest) ?:
+		      /* ... re-initialize the hash with the new digest ... */
+		      new_cb->hash_init(pcpu_shash, new_hash) ?:
+		      /*
+		       * ... feed the old hash into the new state. We may feed
+		       * uninitialized memory into the new state, but this is
+		       * considered no issue and even good as we have some more
+		       * uncertainty here.
+		       */
+		      new_cb->hash_update(pcpu_shash, digest, sizeof(digest));
+		if (ret)
+			goto out;
+
+		/*
+		 * In case the new digest is larger than the old one, cap
+		 * the available entropy to the old message digest used to
+		 * process the existing data.
+		 */
+		found_events = atomic_xchg_relaxed(
+				per_cpu_ptr(&lrng_sched_array_events, cpu), 0);
+		found_events = min_t(u32, found_events, digestsize_events);
+		atomic_add_return_relaxed(found_events,
+				per_cpu_ptr(&lrng_sched_array_events, cpu));
+
+		pr_debug("Re-initialize per-CPU scheduler entropy pool for CPU %d on NUMA node %d with hash %s\n",
+			 cpu, node, new_cb->hash_name());
+	}
+
+out:
+	memzero_explicit(digest, sizeof(digest));
+	return ret;
+}
+
+static u32
+lrng_sched_pool_hash_one(const struct lrng_hash_cb *pcpu_hash_cb,
+			 void *pcpu_hash, int cpu, u8 *digest, u32 *digestsize)
+{
+	struct shash_desc *pcpu_shash =
+		(struct shash_desc *)per_cpu_ptr(lrng_sched_pool, cpu);
+	spinlock_t *lock = per_cpu_ptr(&lrng_sched_lock, cpu);
+	unsigned long flags;
+	u32 digestsize_events, found_events;
+
+	if (unlikely(!per_cpu(lrng_sched_lock_init, cpu))) {
+		if (pcpu_hash_cb->hash_init(pcpu_shash, pcpu_hash)) {
+			pr_warn("Initialization of hash failed\n");
+			return 0;
+		}
+		spin_lock_init(lock);
+		per_cpu(lrng_sched_lock_init, cpu) = true;
+		pr_debug("Initializing per-CPU scheduler entropy pool for CPU %d with hash %s\n",
+			 raw_smp_processor_id(), pcpu_hash_cb->hash_name());
+	}
+
+	/* Lock guarding against reading / writing to per-CPU pool */
+	spin_lock_irqsave(lock, flags);
+
+	*digestsize = pcpu_hash_cb->hash_digestsize(pcpu_hash);
+	digestsize_events = lrng_entropy_to_data(*digestsize << 3,
+						 lrng_sched_entropy_bits);
+
+	/* Obtain entropy statement like for the entropy pool */
+	found_events = atomic_xchg_relaxed(
+				per_cpu_ptr(&lrng_sched_array_events, cpu), 0);
+	/* Cap to maximum amount of data we can hold in hash */
+	found_events = min_t(u32, found_events, digestsize_events);
+
+	/* Cap to maximum amount of data we can hold in array */
+	found_events = min_t(u32, found_events, LRNG_DATA_NUM_VALUES);
+
+	/* Store all not-yet compressed data in data array into hash, ... */
+	if (pcpu_hash_cb->hash_update(pcpu_shash,
+				(u8 *)per_cpu_ptr(lrng_sched_array, cpu),
+				LRNG_DATA_ARRAY_SIZE * sizeof(u32)) ?:
+	    /* ... get the per-CPU pool digest, ... */
+	    pcpu_hash_cb->hash_final(pcpu_shash, digest) ?:
+	    /* ... re-initialize the hash, ... */
+	    pcpu_hash_cb->hash_init(pcpu_shash, pcpu_hash) ?:
+	    /* ... feed the old hash into the new state. */
+	    pcpu_hash_cb->hash_update(pcpu_shash, digest, *digestsize))
+		found_events = 0;
+
+	spin_unlock_irqrestore(lock, flags);
+	return found_events;
+}
+
+/*
+ * Hash all per-CPU arrays and return the digest to be used as seed data for
+ * seeding a DRNG. The caller must guarantee backtracking resistance.
+ * The function will only copy as much data as entropy is available into the
+ * caller-provided output buffer.
+ *
+ * This function handles the translation from the number of received scheduler
+ * events into an entropy statement. The conversion depends on
+ * LRNG_SCHED_ENTROPY_BITS which defines how many scheduler events must be
+ * received to obtain 256 bits of entropy. With this value, the function
+ * lrng_data_to_entropy converts a given data size (received scheduler events,
+ * requested amount of data, etc.) into an entropy statement.
+ * lrng_entropy_to_data does the reverse.
+ *
+ * @eb: entropy buffer to store entropy
+ * @requested_bits: Requested amount of entropy
+ * @fully_seeded: indicator whether LRNG is fully seeded
+ */
+static void lrng_sched_pool_hash(struct entropy_buf *eb, u32 requested_bits,
+				 bool fully_seeded)
+{
+	SHASH_DESC_ON_STACK(shash, NULL);
+	const struct lrng_hash_cb *hash_cb;
+	struct lrng_drng **lrng_drng = lrng_drng_instances();
+	struct lrng_drng *drng = lrng_drng_init_instance();
+	u8 digest[LRNG_MAX_DIGESTSIZE];
+	unsigned long flags, flags2;
+	u32 found_events, collected_events = 0, collected_ent_bits,
+	    requested_events, returned_ent_bits;
+	int ret, cpu;
+	void *hash;
+
+	/* Only deliver entropy when SP800-90B self test is completed */
+	if (!lrng_sp80090b_startup_complete_es(lrng_int_es_sched)) {
+		eb->e_bits[lrng_int_es_sched] = 0;
+		return;
+	}
+
+	/* Lock guarding replacement of per-NUMA hash */
+	read_lock_irqsave(&drng->hash_lock, flags);
+
+	hash_cb = drng->hash_cb;
+	hash = drng->hash;
+
+	/* The hash state of filled with all per-CPU pool hashes. */
+	ret = hash_cb->hash_init(shash, hash);
+	if (ret)
+		goto err;
+
+	/* Cap to maximum entropy that can ever be generated with given hash */
+	lrng_cap_requested(hash_cb->hash_digestsize(hash) << 3, requested_bits);
+	requested_events = lrng_entropy_to_data(requested_bits +
+						lrng_compress_osr(),
+						lrng_sched_entropy_bits);
+
+	/*
+	 * Harvest entropy from each per-CPU hash state - even though we may
+	 * have collected sufficient entropy, we will hash all per-CPU pools.
+	 */
+	for_each_online_cpu(cpu) {
+		struct lrng_drng *pcpu_drng = drng;
+		u32 digestsize, unused_events = 0;
+		int node = cpu_to_node(cpu);
+
+		if (lrng_drng && lrng_drng[node])
+			pcpu_drng = lrng_drng[node];
+
+		if (pcpu_drng == drng) {
+			found_events = lrng_sched_pool_hash_one(hash_cb, hash,
+								cpu, digest,
+								&digestsize);
+		} else {
+			read_lock_irqsave(&pcpu_drng->hash_lock, flags2);
+			found_events =
+				lrng_sched_pool_hash_one(pcpu_drng->hash_cb,
+							 pcpu_drng->hash, cpu,
+							 digest, &digestsize);
+			read_unlock_irqrestore(&pcpu_drng->hash_lock, flags2);
+		}
+
+		/* Store all not-yet compressed data in data array into hash */
+		ret = hash_cb->hash_update(shash, digest, digestsize);
+		if (ret)
+			goto err;
+
+		collected_events += found_events;
+		if (collected_events > requested_events) {
+			unused_events = collected_events - requested_events;
+			atomic_add_return_relaxed(unused_events,
+				per_cpu_ptr(&lrng_sched_array_events, cpu));
+			collected_events = requested_events;
+		}
+		pr_debug("%u scheduler-based events used from entropy array of CPU %d, %u scheduler-based events remain unused\n",
+			 found_events - unused_events, cpu, unused_events);
+	}
+
+	ret = hash_cb->hash_final(shash, digest);
+	if (ret)
+		goto err;
+
+	collected_ent_bits = lrng_data_to_entropy(collected_events,
+						  lrng_sched_entropy_bits);
+	/* Apply oversampling: discount requested oversampling rate */
+	returned_ent_bits = lrng_reduce_by_osr(collected_ent_bits);
+
+	pr_debug("obtained %u bits by collecting %u bits of entropy from scheduler-based noise source\n",
+		 returned_ent_bits, collected_ent_bits);
+
+	/*
+	 * Truncate to available entropy as implicitly allowed by SP800-90B
+	 * section 3.1.5.1.1 table 1 which awards truncated hashes full
+	 * entropy.
+	 *
+	 * During boot time, we read requested_bits data with
+	 * returned_ent_bits entropy. In case our conservative entropy
+	 * estimate underestimates the available entropy we can transport as
+	 * much available entropy as possible.
+	 */
+	memcpy(eb->e[lrng_int_es_sched], digest,
+	       fully_seeded ? returned_ent_bits >> 3 : requested_bits >> 3);
+	eb->e_bits[lrng_int_es_sched] = returned_ent_bits;
+
+out:
+	hash_cb->hash_desc_zero(shash);
+	read_unlock_irqrestore(&drng->hash_lock, flags);
+	memzero_explicit(digest, sizeof(digest));
+	return;
+
+err:
+	eb->e_bits[lrng_int_es_sched] = 0;
+	goto out;
+}
+
+/*
+ * Concatenate full 32 bit word at the end of time array even when current
+ * ptr is not aligned to sizeof(data).
+ */
+static void lrng_sched_array_add_u32(u32 data)
+{
+	/* Increment pointer by number of slots taken for input value */
+	u32 pre_ptr, mask, ptr = this_cpu_add_return(lrng_sched_array_ptr,
+						     LRNG_DATA_SLOTS_PER_UINT);
+	unsigned int pre_array;
+
+	lrng_data_split_u32(&ptr, &pre_ptr, &mask);
+
+	/* MSB of data go into previous unit */
+	pre_array = lrng_data_idx2array(pre_ptr);
+	/* zeroization of slot to ensure the following OR adds the data */
+	this_cpu_and(lrng_sched_array[pre_array], ~(0xffffffff & ~mask));
+	this_cpu_or(lrng_sched_array[pre_array], data & ~mask);
+
+	/*
+	 * Continuous compression is not allowed for scheduler noise source,
+	 * so do not call lrng_sched_array_to_hash here.
+	 */
+
+	/* LSB of data go into current unit */
+	this_cpu_write(lrng_sched_array[lrng_data_idx2array(ptr)],
+		       data & mask);
+}
+
+/* Concatenate data of max LRNG_DATA_SLOTSIZE_MASK at the end of time array */
+static void lrng_sched_array_add_slot(u32 data)
+{
+	/* Get slot */
+	u32 ptr = this_cpu_inc_return(lrng_sched_array_ptr) &
+							LRNG_DATA_WORD_MASK;
+	unsigned int array = lrng_data_idx2array(ptr);
+	unsigned int slot = lrng_data_idx2slot(ptr);
+
+	/* zeroization of slot to ensure the following OR adds the data */
+	this_cpu_and(lrng_sched_array[array],
+		     ~(lrng_data_slot_val(0xffffffff & LRNG_DATA_SLOTSIZE_MASK,
+					  slot)));
+	/* Store data into slot */
+	this_cpu_or(lrng_sched_array[array], lrng_data_slot_val(data, slot));
+
+	/*
+	 * Continuous compression is not allowed for scheduler noise source,
+	 * so do not call lrng_sched_array_to_hash here.
+	 */
+}
+
+static void
+lrng_time_process_common(u32 time, void(*add_time)(u32 data))
+{
+	enum lrng_health_res health_test;
+
+	if (lrng_raw_sched_hires_entropy_store(time))
+		return;
+
+	health_test = lrng_health_test(time, lrng_int_es_sched);
+	if (health_test > lrng_health_fail_use)
+		return;
+
+	if (health_test == lrng_health_pass)
+		atomic_inc_return(this_cpu_ptr(&lrng_sched_array_events));
+
+	add_time(time);
+
+	/*
+	 * We cannot call lrng_es_add_entropy() as this would call a schedule
+	 * operation that is not permissible in scheduler context.
+	 * As the scheduler ES provides a high bandwidth of entropy, we assume
+	 * that other reseed triggers happen to pick up the scheduler ES
+	 * entropy in due time.
+	 */
+}
+
+/* Batching up of entropy in per-CPU array */
+static void lrng_sched_time_process(void)
+{
+	u32 now_time = random_get_entropy();
+
+	if (unlikely(!lrng_gcd_tested())) {
+		/* When GCD is unknown, we process the full time stamp */
+		lrng_time_process_common(now_time, lrng_sched_array_add_u32);
+		lrng_gcd_add_value(now_time);
+	} else {
+		/* GCD is known and applied */
+		lrng_time_process_common((now_time / lrng_gcd_get()) &
+					 LRNG_DATA_SLOTSIZE_MASK,
+					 lrng_sched_array_add_slot);
+	}
+
+	lrng_sched_perf_time(now_time);
+}
+
+void add_sched_randomness(const struct task_struct *p, int cpu)
+{
+	if (lrng_highres_timer()) {
+		lrng_sched_time_process();
+	} else {
+		u32 tmp = cpu;
+
+		tmp ^= lrng_raw_sched_pid_entropy_store(p->pid) ?
+							0 : (u32)p->pid;
+		tmp ^= lrng_raw_sched_starttime_entropy_store(p->start_time) ?
+							0 : (u32)p->start_time;
+		tmp ^= lrng_raw_sched_nvcsw_entropy_store(p->nvcsw) ?
+							0 : (u32)p->nvcsw;
+
+		lrng_sched_time_process();
+		lrng_sched_array_add_u32(tmp);
+	}
+}
+EXPORT_SYMBOL(add_sched_randomness);
+
+static void lrng_sched_es_state(unsigned char *buf, size_t buflen)
+{
+	const struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+
+	/* Assume the lrng_drng_init lock is taken by caller */
+	snprintf(buf, buflen,
+		 " Hash for operating entropy pool: %s\n"
+		 " Available entropy: %u\n"
+		 " per-CPU scheduler event collection size: %u\n"
+		 " Standards compliance: %s\n"
+		 " High-resolution timer: %s\n"
+		 " Health test passed: %s\n",
+		 lrng_drng_init->hash_cb->hash_name(),
+		 lrng_sched_avail_entropy(0),
+		 LRNG_DATA_NUM_VALUES,
+		 lrng_sp80090b_compliant(lrng_int_es_sched) ? "SP800-90B " : "",
+		 lrng_highres_timer() ? "true" : "false",
+		 lrng_sp80090b_startup_complete_es(lrng_int_es_sched) ?
+								      "true" :
+								      "false");
+}
+
+struct lrng_es_cb lrng_es_sched = {
+	.name			= "Scheduler",
+	.get_ent		= lrng_sched_pool_hash,
+	.curr_entropy		= lrng_sched_avail_entropy,
+	.max_entropy		= lrng_sched_avail_pool_size,
+	.state			= lrng_sched_es_state,
+	.reset			= lrng_sched_reset,
+	.switch_hash		= lrng_sched_switch_hash,
+};
diff --git a/drivers/char/lrng/lrng_es_sched.h b/drivers/char/lrng/lrng_es_sched.h
new file mode 100644
index 000000000..f1e596dd8
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_sched.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_SCHED_H
+#define _LRNG_ES_SCHED_H
+
+#include "lrng_es_mgr_cb.h"
+
+#ifdef CONFIG_LRNG_SCHED
+void lrng_sched_es_init(bool highres_timer);
+
+extern struct lrng_es_cb lrng_es_sched;
+
+#else /* CONFIG_LRNG_SCHED */
+static inline void lrng_sched_es_init(bool highres_timer) { }
+#endif /* CONFIG_LRNG_SCHED */
+
+#endif /* _LRNG_ES_SCHED_H */
diff --git a/drivers/char/lrng/lrng_es_timer_common.c b/drivers/char/lrng/lrng_es_timer_common.c
new file mode 100644
index 000000000..70f3ff074
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_timer_common.c
@@ -0,0 +1,144 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Slow Entropy Source: Interrupt data collection
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/gcd.h>
+#include <linux/module.h>
+
+#include "lrng_es_irq.h"
+#include "lrng_es_sched.h"
+#include "lrng_es_timer_common.h"
+#include "lrng_health.h"
+
+/* Is high-resolution timer present? */
+static bool lrng_highres_timer_val = false;
+
+/* Number of time stamps analyzed to calculate a GCD */
+#define LRNG_GCD_WINDOW_SIZE	100
+static u32 lrng_gcd_history[LRNG_GCD_WINDOW_SIZE];
+static atomic_t lrng_gcd_history_ptr = ATOMIC_INIT(-1);
+
+/* The common divisor for all timestamps */
+static u32 lrng_gcd_timer = 0;
+
+bool lrng_gcd_tested(void)
+{
+	return (lrng_gcd_timer != 0);
+}
+
+u32 lrng_gcd_get(void)
+{
+	return lrng_gcd_timer;
+}
+
+/* Set the GCD for use in IRQ ES - if 0, the GCD calculation is restarted. */
+void lrng_gcd_set(u32 running_gcd)
+{
+	lrng_gcd_timer = running_gcd;
+	/* Ensure that update to global variable lrng_gcd_timer is visible */
+	mb();
+}
+
+static void lrng_gcd_set_check(u32 running_gcd)
+{
+	if (!lrng_gcd_tested()) {
+		lrng_gcd_set(running_gcd);
+		pr_debug("Setting GCD to %u\n", running_gcd);
+	}
+}
+
+u32 lrng_gcd_analyze(u32 *history, size_t nelem)
+{
+	u32 running_gcd = 0;
+	size_t i;
+
+	/* Now perform the analysis on the accumulated time data. */
+	for (i = 0; i < nelem; i++) {
+		/*
+		 * NOTE: this would be the place to add more analysis on the
+		 * appropriateness of the timer like checking the presence
+		 * of sufficient variations in the timer.
+		 */
+
+		/*
+		 * This calculates the gcd of all the time values. that is
+		 * gcd(time_1, time_2, ..., time_nelem)
+		 *
+		 * Some timers increment by a fixed (non-1) amount each step.
+		 * This code checks for such increments, and allows the library
+		 * to output the number of such changes have occurred.
+		 */
+		running_gcd = (u32)gcd(history[i], running_gcd);
+
+		/* Zeroize data */
+		history[i] = 0;
+	}
+
+	return running_gcd;
+}
+
+void lrng_gcd_add_value(u32 time)
+{
+	u32 ptr = (u32)atomic_inc_return_relaxed(&lrng_gcd_history_ptr);
+
+	if (ptr < LRNG_GCD_WINDOW_SIZE) {
+		lrng_gcd_history[ptr] = time;
+	} else if (ptr == LRNG_GCD_WINDOW_SIZE) {
+		u32 gcd = lrng_gcd_analyze(lrng_gcd_history,
+					   LRNG_GCD_WINDOW_SIZE);
+
+		if (!gcd)
+			gcd = 1;
+
+		/*
+		 * Ensure that we have variations in the time stamp below the
+		 * given value. This is just a safety measure to prevent the GCD
+		 * becoming too large.
+		 */
+		if (gcd >= 1000) {
+			pr_warn("calculated GCD is larger than expected: %u\n",
+				gcd);
+			gcd = 1000;
+		}
+
+		/*  Adjust all deltas by the observed (small) common factor. */
+		lrng_gcd_set_check(gcd);
+		atomic_set(&lrng_gcd_history_ptr, 0);
+	}
+}
+
+/* Return boolean whether LRNG identified presence of high-resolution timer */
+bool lrng_highres_timer(void)
+{
+	return lrng_highres_timer_val;
+}
+
+static int __init lrng_init_time_source(void)
+{
+	if ((random_get_entropy() & LRNG_DATA_SLOTSIZE_MASK) ||
+	    (random_get_entropy() & LRNG_DATA_SLOTSIZE_MASK)) {
+		/*
+		 * As the highres timer is identified here, previous interrupts
+		 * obtained during boot time are treated like a lowres-timer
+		 * would have been present.
+		 */
+		lrng_highres_timer_val = true;
+	} else {
+		lrng_health_disable();
+		lrng_highres_timer_val = false;
+	}
+
+	lrng_irq_es_init(lrng_highres_timer_val);
+	lrng_sched_es_init(lrng_highres_timer_val);
+
+	/* Ensure that changes to global variables are visible */
+	mb();
+
+	return 0;
+}
+core_initcall(lrng_init_time_source);
diff --git a/drivers/char/lrng/lrng_es_timer_common.h b/drivers/char/lrng/lrng_es_timer_common.h
new file mode 100644
index 000000000..b45b9f683
--- /dev/null
+++ b/drivers/char/lrng/lrng_es_timer_common.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * LRNG Slow Noise Source: Time stamp array handling
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_ES_TIMER_COMMON_H
+#define _LRNG_ES_TIMER_COMMON_H
+
+bool lrng_gcd_tested(void);
+void lrng_gcd_set(u32 running_gcd);
+u32 lrng_gcd_get(void);
+u32 lrng_gcd_analyze(u32 *history, size_t nelem);
+void lrng_gcd_add_value(u32 time);
+bool lrng_highres_timer(void);
+
+/*
+ * To limit the impact on the interrupt handling, the LRNG concatenates
+ * entropic LSB parts of the time stamps in a per-CPU array and only
+ * injects them into the entropy pool when the array is full.
+ */
+
+/* Store multiple integers in one u32 */
+#define LRNG_DATA_SLOTSIZE_BITS		(8)
+#define LRNG_DATA_SLOTSIZE_MASK		((1 << LRNG_DATA_SLOTSIZE_BITS) - 1)
+#define LRNG_DATA_ARRAY_MEMBER_BITS	(4 << 3) /* ((sizeof(u32)) << 3) */
+#define LRNG_DATA_SLOTS_PER_UINT	(LRNG_DATA_ARRAY_MEMBER_BITS / \
+					 LRNG_DATA_SLOTSIZE_BITS)
+
+/*
+ * Number of time values to store in the array - in small environments
+ * only one atomic_t variable per CPU is used.
+ */
+#define LRNG_DATA_NUM_VALUES		(CONFIG_LRNG_COLLECTION_SIZE)
+/* Mask of LSB of time stamp to store */
+#define LRNG_DATA_WORD_MASK		(LRNG_DATA_NUM_VALUES - 1)
+
+#define LRNG_DATA_SLOTS_MASK		(LRNG_DATA_SLOTS_PER_UINT - 1)
+#define LRNG_DATA_ARRAY_SIZE		(LRNG_DATA_NUM_VALUES /	\
+					 LRNG_DATA_SLOTS_PER_UINT)
+
+/* Starting bit index of slot */
+static inline unsigned int lrng_data_slot2bitindex(unsigned int slot)
+{
+	return (LRNG_DATA_SLOTSIZE_BITS * slot);
+}
+
+/* Convert index into the array index */
+static inline unsigned int lrng_data_idx2array(unsigned int idx)
+{
+	return idx / LRNG_DATA_SLOTS_PER_UINT;
+}
+
+/* Convert index into the slot of a given array index */
+static inline unsigned int lrng_data_idx2slot(unsigned int idx)
+{
+	return idx & LRNG_DATA_SLOTS_MASK;
+}
+
+/* Convert value into slot value */
+static inline unsigned int lrng_data_slot_val(unsigned int val,
+					      unsigned int slot)
+{
+	return val << lrng_data_slot2bitindex(slot);
+}
+
+/*
+ * Return the pointers for the previous and current units to inject a u32 into.
+ * Also return the mask which the u32 word is to be processed.
+ */
+static inline void lrng_data_split_u32(u32 *ptr, u32 *pre_ptr, u32 *mask)
+{
+	/* ptr to previous unit */
+	*pre_ptr = (*ptr - LRNG_DATA_SLOTS_PER_UINT) & LRNG_DATA_WORD_MASK;
+	*ptr &= LRNG_DATA_WORD_MASK;
+
+	/* mask to split data into the two parts for the two units */
+	*mask = ((1 << (*pre_ptr & (LRNG_DATA_SLOTS_PER_UINT - 1)) *
+			LRNG_DATA_SLOTSIZE_BITS)) - 1;
+}
+
+#endif /* _LRNG_ES_TIMER_COMMON_H */
\ No newline at end of file
diff --git a/drivers/char/lrng/lrng_hash_kcapi.c b/drivers/char/lrng/lrng_hash_kcapi.c
new file mode 100644
index 000000000..13e62db9b
--- /dev/null
+++ b/drivers/char/lrng/lrng_hash_kcapi.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Backend for providing the hash primitive using the kernel crypto API.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <crypto/hash.h>
+#include <linux/module.h>
+
+
+static char *lrng_hash_name = "sha512";
+
+/* The parameter must be r/o in sysfs as otherwise races appear. */
+module_param(lrng_hash_name, charp, 0444);
+MODULE_PARM_DESC(lrng_hash_name, "Kernel crypto API hash name");
+
+struct lrng_hash_info {
+	struct crypto_shash *tfm;
+};
+
+static const char *lrng_kcapi_hash_name(void)
+{
+	return lrng_hash_name;
+}
+
+static void _lrng_kcapi_hash_free(struct lrng_hash_info *lrng_hash)
+{
+	struct crypto_shash *tfm = lrng_hash->tfm;
+
+	crypto_free_shash(tfm);
+	kfree(lrng_hash);
+}
+
+static void *lrng_kcapi_hash_alloc(const char *name)
+{
+	struct lrng_hash_info *lrng_hash;
+	struct crypto_shash *tfm;
+	int ret;
+
+	if (!name) {
+		pr_err("Hash name missing\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	tfm = crypto_alloc_shash(name, 0, 0);
+	if (IS_ERR(tfm)) {
+		pr_err("could not allocate hash %s\n", name);
+		return ERR_CAST(tfm);
+	}
+
+	ret = sizeof(struct lrng_hash_info);
+	lrng_hash = kmalloc(ret, GFP_KERNEL);
+	if (!lrng_hash) {
+		crypto_free_shash(tfm);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	lrng_hash->tfm = tfm;
+
+	pr_info("Hash %s allocated\n", name);
+
+	return lrng_hash;
+}
+
+static void *lrng_kcapi_hash_name_alloc(void)
+{
+	return lrng_kcapi_hash_alloc(lrng_kcapi_hash_name());
+}
+
+static u32 lrng_kcapi_hash_digestsize(void *hash)
+{
+	struct lrng_hash_info *lrng_hash = (struct lrng_hash_info *)hash;
+	struct crypto_shash *tfm = lrng_hash->tfm;
+
+	return crypto_shash_digestsize(tfm);
+}
+
+static void lrng_kcapi_hash_dealloc(void *hash)
+{
+	struct lrng_hash_info *lrng_hash = (struct lrng_hash_info *)hash;
+
+	_lrng_kcapi_hash_free(lrng_hash);
+	pr_info("Hash deallocated\n");
+}
+
+static int lrng_kcapi_hash_init(struct shash_desc *shash, void *hash)
+{
+	struct lrng_hash_info *lrng_hash = (struct lrng_hash_info *)hash;
+	struct crypto_shash *tfm = lrng_hash->tfm;
+
+	shash->tfm = tfm;
+	return crypto_shash_init(shash);
+}
+
+static int lrng_kcapi_hash_update(struct shash_desc *shash, const u8 *inbuf,
+			   u32 inbuflen)
+{
+	return crypto_shash_update(shash, inbuf, inbuflen);
+}
+
+static int lrng_kcapi_hash_final(struct shash_desc *shash, u8 *digest)
+{
+	return crypto_shash_final(shash, digest);
+}
+
+static void lrng_kcapi_hash_zero(struct shash_desc *shash)
+{
+	shash_desc_zero(shash);
+}
+
+static const struct lrng_hash_cb lrng_kcapi_hash_cb = {
+	.hash_name		= lrng_kcapi_hash_name,
+	.hash_alloc		= lrng_kcapi_hash_name_alloc,
+	.hash_dealloc		= lrng_kcapi_hash_dealloc,
+	.hash_digestsize	= lrng_kcapi_hash_digestsize,
+	.hash_init		= lrng_kcapi_hash_init,
+	.hash_update		= lrng_kcapi_hash_update,
+	.hash_final		= lrng_kcapi_hash_final,
+	.hash_desc_zero		= lrng_kcapi_hash_zero,
+};
+
+static int __init lrng_kcapi_init(void)
+{
+	return lrng_set_hash_cb(&lrng_kcapi_hash_cb);
+}
+
+static void __exit lrng_kcapi_exit(void)
+{
+	lrng_set_hash_cb(NULL);
+}
+
+late_initcall(lrng_kcapi_init);
+module_exit(lrng_kcapi_exit);
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
+MODULE_DESCRIPTION("Entropy Source and DRNG Manager - Kernel crypto API hash backend");
diff --git a/drivers/char/lrng/lrng_health.c b/drivers/char/lrng/lrng_health.c
new file mode 100644
index 000000000..2c884d1c1
--- /dev/null
+++ b/drivers/char/lrng/lrng_health.c
@@ -0,0 +1,447 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Entropy Source and DRNG Manager (LRNG) Health Testing
+ *
+ * Copyright (C) 2022 - 2023, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/fips.h>
+#include <linux/module.h>
+
+#include "lrng_definitions.h"
+#include "lrng_es_mgr.h"
+#include "lrng_health.h"
+
+/* Stuck Test */
+struct lrng_stuck_test {
+	u32 last_time;		/* Stuck test: time of previous IRQ */
+	u32 last_delta;		/* Stuck test: delta of previous IRQ */
+	u32 last_delta2;	/* Stuck test: 2. time derivation of prev IRQ */
+};
+
+/* Repetition Count Test */
+struct lrng_rct {
+	atomic_t rct_count;	/* Number of stuck values */
+};
+
+/* Adaptive Proportion Test */
+struct lrng_apt {
+	/* Data window size */
+#define LRNG_APT_WINDOW_SIZE	512
+	/* LSB of time stamp to process */
+#define LRNG_APT_LSB		16
+#define LRNG_APT_WORD_MASK	(LRNG_APT_LSB - 1)
+	atomic_t apt_count;		/* APT counter */
+	atomic_t apt_base;		/* APT base reference */
+
+	atomic_t apt_trigger;
+	bool apt_base_set;	/* Is APT base set? */
+};
+
+/* Health data collected for one entropy source */
+struct lrng_health_es_state {
+	struct lrng_rct rct;
+	struct lrng_apt apt;
+
+	/* SP800-90B startup health tests */
+#define LRNG_SP80090B_STARTUP_SAMPLES  1024
+#define LRNG_SP80090B_STARTUP_BLOCKS   ((LRNG_SP80090B_STARTUP_SAMPLES + \
+					 LRNG_APT_WINDOW_SIZE - 1) /    \
+					LRNG_APT_WINDOW_SIZE)
+	bool sp80090b_startup_done;
+	atomic_t sp80090b_startup_blocks;
+};
+
+#define LRNG_HEALTH_ES_INIT(x) \
+	x.rct.rct_count = ATOMIC_INIT(0), \
+	x.apt.apt_count = ATOMIC_INIT(0), \
+	x.apt.apt_base = ATOMIC_INIT(-1), \
+	x.apt.apt_trigger = ATOMIC_INIT(LRNG_APT_WINDOW_SIZE), \
+	x.apt.apt_base_set = false, \
+	x.sp80090b_startup_blocks = ATOMIC_INIT(LRNG_SP80090B_STARTUP_BLOCKS), \
+	x.sp80090b_startup_done = false,
+
+/* The health test code must operate lock-less */
+struct lrng_health {
+	bool health_test_enabled;
+	struct lrng_health_es_state es_state[lrng_int_es_last];
+};
+
+static struct lrng_health lrng_health = {
+	.health_test_enabled = true,
+
+#ifdef CONFIG_LRNG_IRQ
+	LRNG_HEALTH_ES_INIT(.es_state[lrng_int_es_irq])
+#endif
+#ifdef CONFIG_LRNG_SCHED
+	LRNG_HEALTH_ES_INIT(.es_state[lrng_int_es_sched])
+#endif
+};
+
+static DEFINE_PER_CPU(struct lrng_stuck_test[lrng_int_es_last],
+		      lrng_stuck_test_array);
+
+static bool lrng_sp80090b_health_requested(void)
+{
+	/* Health tests are only requested in FIPS mode */
+	return fips_enabled;
+}
+
+static bool lrng_sp80090b_health_enabled(void)
+{
+	struct lrng_health *health = &lrng_health;
+
+	return lrng_sp80090b_health_requested() && health->health_test_enabled;
+}
+
+/***************************************************************************
+ * SP800-90B Compliance
+ *
+ * If the Linux-RNG is booted into FIPS mode, the following interfaces
+ * provide an SP800-90B compliant noise source:
+ *
+ * * /dev/random
+ * * getrandom(2)
+ * * get_random_bytes_full
+ *
+ * All other interfaces, including /dev/urandom or get_random_bytes without
+ * the add_random_ready_callback cannot claim to use an SP800-90B compliant
+ * noise source.
+ ***************************************************************************/
+
+/*
+ * Perform SP800-90B startup testing
+ */
+static void lrng_sp80090b_startup(struct lrng_health *health,
+				  enum lrng_internal_es es)
+{
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+
+	if (!es_state->sp80090b_startup_done &&
+	    atomic_dec_and_test(&es_state->sp80090b_startup_blocks)) {
+		es_state->sp80090b_startup_done = true;
+		pr_info("SP800-90B startup health tests for internal entropy source %u completed\n",
+			es);
+		lrng_drng_force_reseed();
+
+		/*
+		 * We cannot call lrng_es_add_entropy() as this may cause a
+		 * schedule operation while in scheduler context for the
+		 * scheduler ES.
+		 */
+	}
+}
+
+/*
+ * Handle failure of SP800-90B startup testing
+ */
+static void lrng_sp80090b_startup_failure(struct lrng_health *health,
+					  enum lrng_internal_es es)
+{
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+
+
+	/* Reset of LRNG and its entropy - NOTE: we are in atomic context */
+	lrng_reset();
+
+	/*
+	 * Reset the SP800-90B startup test.
+	 *
+	 * NOTE SP800-90B section 4.3 bullet 4 does not specify what
+	 * exactly is to be done in case of failure! Thus, we do what
+	 * makes sense, i.e. restarting the health test and thus gating
+	 * the output function of /dev/random and getrandom(2).
+	 */
+	atomic_set(&es_state->sp80090b_startup_blocks,
+		   LRNG_SP80090B_STARTUP_BLOCKS);
+}
+
+/*
+ * Handle failure of SP800-90B runtime testing
+ */
+static void lrng_sp80090b_runtime_failure(struct lrng_health *health,
+					  enum lrng_internal_es es)
+{
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+
+	lrng_sp80090b_startup_failure(health, es);
+	es_state->sp80090b_startup_done = false;
+}
+
+static void lrng_rct_reset(struct lrng_rct *rct);
+static void lrng_apt_reset(struct lrng_apt *apt, unsigned int time_masked);
+static void lrng_apt_restart(struct lrng_apt *apt);
+static void lrng_sp80090b_permanent_failure(struct lrng_health *health,
+					    enum lrng_internal_es es)
+{
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+	struct lrng_apt *apt = &es_state->apt;
+	struct lrng_rct *rct = &es_state->rct;
+
+	if (lrng_enforce_panic_on_permanent_health_failure()) {
+		panic("SP800-90B permanent health test failure for internal entropy source %u\n",
+		      es);
+	}
+
+	pr_err("SP800-90B permanent health test failure for internal entropy source %u - invalidating all existing entropy and initiate SP800-90B startup\n",
+	       es);
+	lrng_sp80090b_runtime_failure(health, es);
+
+	lrng_rct_reset(rct);
+	lrng_apt_reset(apt, 0);
+	lrng_apt_restart(apt);
+}
+
+static void lrng_sp80090b_failure(struct lrng_health *health,
+				  enum lrng_internal_es es)
+{
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+
+	if (es_state->sp80090b_startup_done) {
+		pr_warn("SP800-90B runtime health test failure for internal entropy source %u - invalidating all existing entropy and initiate SP800-90B startup\n", es);
+		lrng_sp80090b_runtime_failure(health, es);
+	} else {
+		pr_warn("SP800-90B startup test failure for internal entropy source %u - resetting\n", es);
+		lrng_sp80090b_startup_failure(health, es);
+	}
+}
+
+bool lrng_sp80090b_startup_complete_es(enum lrng_internal_es es)
+{
+	struct lrng_health *health = &lrng_health;
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+
+	if (!lrng_sp80090b_health_enabled())
+		return true;
+
+	return es_state->sp80090b_startup_done;
+}
+
+bool lrng_sp80090b_compliant(enum lrng_internal_es es)
+{
+	struct lrng_health *health = &lrng_health;
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+
+	return lrng_sp80090b_health_enabled() &&
+	       es_state->sp80090b_startup_done;
+}
+
+/***************************************************************************
+ * Adaptive Proportion Test
+ *
+ * This test complies with SP800-90B section 4.4.2.
+ ***************************************************************************/
+
+/*
+ * Reset the APT counter
+ *
+ * @health [in] Reference to health state
+ */
+static void lrng_apt_reset(struct lrng_apt *apt, unsigned int time_masked)
+{
+	/* Reset APT */
+	atomic_set(&apt->apt_count, 0);
+	atomic_set(&apt->apt_base, time_masked);
+}
+
+static void lrng_apt_restart(struct lrng_apt *apt)
+{
+	atomic_set(&apt->apt_trigger, LRNG_APT_WINDOW_SIZE);
+}
+
+/*
+ * Insert a new entropy event into APT
+ *
+ * This function does is void as it does not decide about the fate of a time
+ * stamp. An APT failure can only happen at the same time of a stuck test
+ * failure. Thus, the stuck failure will already decide how the time stamp
+ * is handled.
+ *
+ * @health [in] Reference to health state
+ * @now_time [in] Time stamp to process
+ */
+static void lrng_apt_insert(struct lrng_health *health,
+			    unsigned int now_time, enum lrng_internal_es es)
+{
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+	struct lrng_apt *apt = &es_state->apt;
+
+	if (!lrng_sp80090b_health_requested())
+		return;
+
+	now_time &= LRNG_APT_WORD_MASK;
+
+	/* Initialization of APT */
+	if (!apt->apt_base_set) {
+		atomic_set(&apt->apt_base, now_time);
+		apt->apt_base_set = true;
+		return;
+	}
+
+	if (now_time == (unsigned int)atomic_read(&apt->apt_base)) {
+		u32 apt_val = (u32)atomic_inc_return_relaxed(&apt->apt_count);
+
+		if (apt_val >= CONFIG_LRNG_APT_CUTOFF_PERMANENT)
+			lrng_sp80090b_permanent_failure(health, es);
+		else if (apt_val >= CONFIG_LRNG_APT_CUTOFF)
+			lrng_sp80090b_failure(health, es);
+	}
+
+	if (atomic_dec_and_test(&apt->apt_trigger)) {
+		lrng_apt_restart(apt);
+		lrng_apt_reset(apt, now_time);
+		lrng_sp80090b_startup(health, es);
+	}
+}
+
+/***************************************************************************
+ * Repetition Count Test
+ *
+ * The LRNG uses an enhanced version of the Repetition Count Test
+ * (RCT) specified in SP800-90B section 4.4.1. Instead of counting identical
+ * back-to-back values, the input to the RCT is the counting of the stuck
+ * values while filling the entropy pool.
+ *
+ * The RCT is applied with an alpha of 2^-30 compliant to FIPS 140-2 IG 9.8.
+ *
+ * During the counting operation, the LRNG always calculates the RCT
+ * cut-off value of C. If that value exceeds the allowed cut-off value,
+ * the LRNG will invalidate all entropy for the entropy pool which implies
+ * that no data can be extracted from the entropy pool unless new entropy
+ * is received.
+ ***************************************************************************/
+
+static void lrng_rct_reset(struct lrng_rct *rct)
+{
+	/* Reset RCT */
+	atomic_set(&rct->rct_count, 0);
+}
+
+/*
+ * Hot code path - Insert data for Repetition Count Test
+ *
+ * @health: Reference to health information
+ * @stuck: Decision of stuck test
+ */
+static void lrng_rct(struct lrng_health *health, enum lrng_internal_es es,
+		     int stuck)
+{
+	struct lrng_health_es_state *es_state = &health->es_state[es];
+	struct lrng_rct *rct = &es_state->rct;
+
+	if (!lrng_sp80090b_health_requested())
+		return;
+
+	if (stuck) {
+		u32 rct_count = atomic_add_return_relaxed(1, &rct->rct_count);
+
+		/*
+		 * The cutoff value is based on the following consideration:
+		 * alpha = 2^-30 as recommended in FIPS 140-2 IG 9.8.
+		 * In addition, we imply an entropy value H of 1 bit as this
+		 * is the minimum entropy required to provide full entropy.
+		 *
+		 * Note, rct_count (which equals to value B in the
+		 * pseudo code of SP800-90B section 4.4.1) starts with zero.
+		 * Hence we need to subtract one from the cutoff value as
+		 * calculated following SP800-90B.
+		 */
+		if (rct_count >= CONFIG_LRNG_RCT_CUTOFF_PERMANENT)
+			lrng_sp80090b_permanent_failure(health, es);
+		else if (rct_count >= CONFIG_LRNG_RCT_CUTOFF)
+			lrng_sp80090b_failure(health, es);
+	} else {
+		lrng_rct_reset(rct);
+	}
+}
+
+/***************************************************************************
+ * Stuck Test
+ *
+ * Checking the:
+ *      1st derivative of the event occurrence (time delta)
+ *      2nd derivative of the event occurrence (delta of time deltas)
+ *      3rd derivative of the event occurrence (delta of delta of time deltas)
+ *
+ * All values must always be non-zero. The stuck test is only valid disabled if
+ * high-resolution time stamps are identified after initialization.
+ ***************************************************************************/
+
+static u32 lrng_delta(u32 prev, u32 next)
+{
+	/*
+	 * Note that this (unsigned) subtraction does yield the correct value
+	 * in the wraparound-case, i.e. when next < prev.
+	 */
+	return (next - prev);
+}
+
+/*
+ * Hot code path
+ *
+ * @health: Reference to health information
+ * @now: Event time
+ * @return: 0 event occurrence not stuck (good time stamp)
+ *	    != 0 event occurrence stuck (reject time stamp)
+ */
+static int lrng_irq_stuck(enum lrng_internal_es es, u32 now_time)
+{
+	struct lrng_stuck_test *stuck = this_cpu_ptr(lrng_stuck_test_array);
+	u32 delta = lrng_delta(stuck[es].last_time, now_time);
+	u32 delta2 = lrng_delta(stuck[es].last_delta, delta);
+	u32 delta3 = lrng_delta(stuck[es].last_delta2, delta2);
+
+	stuck[es].last_time = now_time;
+	stuck[es].last_delta = delta;
+	stuck[es].last_delta2 = delta2;
+
+	if (!delta || !delta2 || !delta3)
+		return 1;
+
+	return 0;
+}
+
+/***************************************************************************
+ * Health test interfaces
+ ***************************************************************************/
+
+/*
+ * Disable all health tests
+ */
+void lrng_health_disable(void)
+{
+	struct lrng_health *health = &lrng_health;
+
+	health->health_test_enabled = false;
+
+	if (lrng_sp80090b_health_requested())
+		pr_warn("SP800-90B compliance requested but the Linux RNG is NOT SP800-90B compliant\n");
+}
+
+/*
+ * Hot code path - Perform health test on time stamp received from an event
+ *
+ * @now_time Time stamp
+ */
+enum lrng_health_res lrng_health_test(u32 now_time, enum lrng_internal_es es)
+{
+	struct lrng_health *health = &lrng_health;
+	int stuck;
+
+	if (!health->health_test_enabled)
+		return lrng_health_pass;
+
+	lrng_apt_insert(health, now_time, es);
+
+	stuck = lrng_irq_stuck(es, now_time);
+	lrng_rct(health, es, stuck);
+	if (stuck) {
+		/* SP800-90B disallows using a failing health test time stamp */
+		return lrng_sp80090b_health_requested() ?
+			lrng_health_fail_drop : lrng_health_fail_use;
+	}
+
+	return lrng_health_pass;
+}
diff --git a/drivers/char/lrng/lrng_health.h b/drivers/char/lrng/lrng_health.h
new file mode 100644
index 000000000..4f9f5033f
--- /dev/null
+++ b/drivers/char/lrng/lrng_health.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_HEALTH_H
+#define _LRNG_HEALTH_H
+
+#include "lrng_es_mgr.h"
+
+enum lrng_health_res {
+	lrng_health_pass,		/* Health test passes on time stamp */
+	lrng_health_fail_use,		/* Time stamp unhealthy, but mix in */
+	lrng_health_fail_drop		/* Time stamp unhealthy, drop it */
+};
+
+#ifdef CONFIG_LRNG_HEALTH_TESTS
+bool lrng_sp80090b_startup_complete_es(enum lrng_internal_es es);
+bool lrng_sp80090b_compliant(enum lrng_internal_es es);
+
+enum lrng_health_res lrng_health_test(u32 now_time, enum lrng_internal_es es);
+void lrng_health_disable(void);
+#else	/* CONFIG_LRNG_HEALTH_TESTS */
+static inline bool lrng_sp80090b_startup_complete_es(enum lrng_internal_es es)
+{
+	return true;
+}
+
+static inline bool lrng_sp80090b_compliant(enum lrng_internal_es es)
+{
+	return false;
+}
+
+static inline enum lrng_health_res
+lrng_health_test(u32 now_time, enum lrng_internal_es es)
+{
+	return lrng_health_pass;
+}
+static inline void lrng_health_disable(void) { }
+#endif	/* CONFIG_LRNG_HEALTH_TESTS */
+
+#endif /* _LRNG_HEALTH_H */
diff --git a/drivers/char/lrng/lrng_interface_aux.c b/drivers/char/lrng/lrng_interface_aux.c
new file mode 100644
index 000000000..84f3ce38f
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_aux.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG auxiliary interfaces
+ *
+ * Copyright (C) 2022 Stephan Mueller <smueller@chronox.de>
+ * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All
+ * Rights Reserved.
+ * Copyright (C) 2016 Jason Cooper <jason@lakedaemon.net>
+ */
+
+#include <linux/lrng.h>
+#include <linux/mm.h>
+#include <linux/random.h>
+
+#include "lrng_es_mgr.h"
+#include "lrng_interface_random_kernel.h"
+
+/*
+ * Fill a buffer with random numbers and tokenize it to provide random numbers
+ * to callers in fixed chunks. This approach is provided to be consistent with
+ * the Linux kernel interface requirements. Yet, this approach violate the
+ * backtracking resistance of the random number generator. Thus, the provided
+ * random numbers are not considered to be as strong as those requested directly
+ * from the LRNG.
+ */
+struct batched_entropy {
+	union {
+		u64 entropy_u64[LRNG_DRNG_BLOCKSIZE / sizeof(u64)];
+		u32 entropy_u32[LRNG_DRNG_BLOCKSIZE / sizeof(u32)];
+		u16 entropy_u16[LRNG_DRNG_BLOCKSIZE / sizeof(u16)];
+		u8 entropy_u8[LRNG_DRNG_BLOCKSIZE / sizeof(u8)];
+	};
+	unsigned int position;
+	spinlock_t batch_lock;
+};
+
+/*
+ * Get a random word for internal kernel use only. The quality of the random
+ * number is as good as /dev/urandom, but there is no backtrack protection,
+ * with the goal of being quite fast and not depleting entropy.
+ */
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u64) = {
+	.batch_lock	= __SPIN_LOCK_UNLOCKED(batched_entropy_u64.lock),
+};
+
+u64 get_random_u64(void)
+{
+	u64 ret;
+	unsigned long flags;
+	struct batched_entropy *batch;
+
+	lrng_debug_report_seedlevel("get_random_u64");
+
+	batch = raw_cpu_ptr(&batched_entropy_u64);
+	spin_lock_irqsave(&batch->batch_lock, flags);
+	if (batch->position % ARRAY_SIZE(batch->entropy_u64) == 0) {
+		lrng_get_random_bytes(batch->entropy_u64, LRNG_DRNG_BLOCKSIZE);
+		batch->position = 0;
+	}
+	ret = batch->entropy_u64[batch->position++];
+	spin_unlock_irqrestore(&batch->batch_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(get_random_u64);
+
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u32) = {
+	.batch_lock	= __SPIN_LOCK_UNLOCKED(batched_entropy_u32.lock),
+};
+
+u32 get_random_u32(void)
+{
+	u32 ret;
+	unsigned long flags;
+	struct batched_entropy *batch;
+
+	lrng_debug_report_seedlevel("get_random_u32");
+
+	batch = raw_cpu_ptr(&batched_entropy_u32);
+	spin_lock_irqsave(&batch->batch_lock, flags);
+	if (batch->position % ARRAY_SIZE(batch->entropy_u32) == 0) {
+		lrng_get_random_bytes(batch->entropy_u32, LRNG_DRNG_BLOCKSIZE);
+		batch->position = 0;
+	}
+	ret = batch->entropy_u32[batch->position++];
+	spin_unlock_irqrestore(&batch->batch_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(get_random_u32);
+
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u16) = {
+	.batch_lock	= __SPIN_LOCK_UNLOCKED(batched_entropy_u16.lock),
+};
+
+u16 get_random_u16(void)
+{
+	u16 ret;
+	unsigned long flags;
+	struct batched_entropy *batch;
+
+	lrng_debug_report_seedlevel("get_random_u16");
+
+	batch = raw_cpu_ptr(&batched_entropy_u16);
+	spin_lock_irqsave(&batch->batch_lock, flags);
+	if (batch->position % ARRAY_SIZE(batch->entropy_u16) == 0) {
+		lrng_get_random_bytes(batch->entropy_u16, LRNG_DRNG_BLOCKSIZE);
+		batch->position = 0;
+	}
+	ret = batch->entropy_u16[batch->position++];
+	spin_unlock_irqrestore(&batch->batch_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(get_random_u16);
+
+static DEFINE_PER_CPU(struct batched_entropy, batched_entropy_u8) = {
+	.batch_lock	= __SPIN_LOCK_UNLOCKED(batched_entropy_u8.lock),
+};
+
+u8 get_random_u8(void)
+{
+	u8 ret;
+	unsigned long flags;
+	struct batched_entropy *batch;
+
+	lrng_debug_report_seedlevel("get_random_u8");
+
+	batch = raw_cpu_ptr(&batched_entropy_u8);
+	spin_lock_irqsave(&batch->batch_lock, flags);
+	if (batch->position % ARRAY_SIZE(batch->entropy_u8) == 0) {
+		lrng_get_random_bytes(batch->entropy_u8, LRNG_DRNG_BLOCKSIZE);
+		batch->position = 0;
+	}
+	ret = batch->entropy_u8[batch->position++];
+	spin_unlock_irqrestore(&batch->batch_lock, flags);
+	return ret;
+}
+EXPORT_SYMBOL(get_random_u8);
+
+/* Taken directly from random.c */
+u32 __get_random_u32_below(u32 ceil)
+{
+	u64 mult = (u64)ceil * get_random_u32();
+	if (unlikely((u32)mult < ceil)) {
+		u32 bound = -ceil % ceil;
+		while (unlikely((u32)mult < bound))
+			mult = (u64)ceil * get_random_u32();
+	}
+	return mult >> 32;
+}
+EXPORT_SYMBOL(__get_random_u32_below);
+
+#ifdef CONFIG_SMP
+/*
+ * This function is called when the CPU is coming up, with entry
+ * CPUHP_RANDOM_PREPARE, which comes before CPUHP_WORKQUEUE_PREP.
+ */
+int random_prepare_cpu(unsigned int cpu)
+{
+	/*
+	 * When the cpu comes back online, immediately invalidate all batches,
+	 * so that we serve fresh randomness.
+	 */
+	per_cpu_ptr(&batched_entropy_u8, cpu)->position = 0;
+	per_cpu_ptr(&batched_entropy_u16, cpu)->position = 0;
+	per_cpu_ptr(&batched_entropy_u32, cpu)->position = 0;
+	per_cpu_ptr(&batched_entropy_u64, cpu)->position = 0;
+	return 0;
+}
+
+int random_online_cpu(unsigned int cpu)
+{
+        return 0;
+}
+#endif
+
+/*
+ * It's important to invalidate all potential batched entropy that might
+ * be stored before the crng is initialized, which we can do lazily by
+ * simply resetting the counter to zero so that it's re-extracted on the
+ * next usage.
+ */
+void invalidate_batched_entropy(void)
+{
+	int cpu;
+	unsigned long flags;
+
+	for_each_possible_cpu(cpu) {
+		struct batched_entropy *batched_entropy;
+
+		batched_entropy = per_cpu_ptr(&batched_entropy_u8, cpu);
+		spin_lock_irqsave(&batched_entropy->batch_lock, flags);
+		batched_entropy->position = 0;
+		spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
+
+		batched_entropy = per_cpu_ptr(&batched_entropy_u16, cpu);
+		spin_lock_irqsave(&batched_entropy->batch_lock, flags);
+		batched_entropy->position = 0;
+		spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
+
+		batched_entropy = per_cpu_ptr(&batched_entropy_u32, cpu);
+		spin_lock_irqsave(&batched_entropy->batch_lock, flags);
+		batched_entropy->position = 0;
+		spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
+
+		batched_entropy = per_cpu_ptr(&batched_entropy_u64, cpu);
+		spin_lock(&batched_entropy->batch_lock);
+		batched_entropy->position = 0;
+		spin_unlock_irqrestore(&batched_entropy->batch_lock, flags);
+	}
+}
diff --git a/drivers/char/lrng/lrng_interface_dev.c b/drivers/char/lrng/lrng_interface_dev.c
new file mode 100644
index 000000000..e60060d40
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_dev.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG user space device file interface
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+
+#include "lrng_interface_dev_common.h"
+
+static const struct file_operations lrng_fops = {
+	.read  = lrng_drng_read_block,
+	.write = lrng_drng_write,
+	.poll  = lrng_random_poll,
+	.unlocked_ioctl = lrng_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
+	.fasync = lrng_fasync,
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice lrng_miscdev = {
+	.minor          = MISC_DYNAMIC_MINOR,
+	.name           = "lrng",
+	.nodename       = "lrng",
+	.fops           = &lrng_fops,
+	.mode		= 0666
+};
+
+static int __init lrng_dev_if_mod_init(void)
+{
+	return misc_register(&lrng_miscdev);
+}
+device_initcall(lrng_dev_if_mod_init);
diff --git a/drivers/char/lrng/lrng_interface_dev_common.c b/drivers/char/lrng/lrng_interface_dev_common.c
new file mode 100644
index 000000000..a2845e278
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_dev_common.c
@@ -0,0 +1,315 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG User and kernel space interfaces
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/random.h>
+#include <linux/slab.h>
+
+#include "lrng_drng_mgr.h"
+#include "lrng_es_aux.h"
+#include "lrng_es_mgr.h"
+#include "lrng_interface_dev_common.h"
+
+DECLARE_WAIT_QUEUE_HEAD(lrng_write_wait);
+static struct fasync_struct *fasync;
+
+static bool lrng_seed_hw = true;	/* Allow HW to provide seed */
+static bool lrng_seed_user = true;	/* Allow user space to provide seed */
+
+/********************************** Helper ***********************************/
+
+static u32 lrng_get_aux_ent(void)
+{
+	return lrng_es[lrng_ext_es_aux]->curr_entropy(0);
+}
+
+/* Is the DRNG seed level too low? */
+bool lrng_need_entropy(void)
+{
+	return (lrng_get_aux_ent() < lrng_write_wakeup_bits);
+}
+
+void lrng_writer_wakeup(void)
+{
+	if (lrng_need_entropy() && wq_has_sleeper(&lrng_write_wait)) {
+		wake_up_interruptible(&lrng_write_wait);
+		kill_fasync(&fasync, SIGIO, POLL_OUT);
+	}
+}
+
+void lrng_init_wakeup_dev(void)
+{
+	kill_fasync(&fasync, SIGIO, POLL_IN);
+}
+
+/* External entropy provider is allowed to provide seed data */
+bool lrng_state_exseed_allow(enum lrng_external_noise_source source)
+{
+	if (source == lrng_noise_source_hw)
+		return lrng_seed_hw;
+	return lrng_seed_user;
+}
+
+/* Enable / disable external entropy provider to furnish seed */
+void lrng_state_exseed_set(enum lrng_external_noise_source source, bool type)
+{
+	/*
+	 * If the LRNG is not yet operational, allow all entropy sources
+	 * to deliver data unconditionally to get fully seeded asap.
+	 */
+	if (!lrng_state_operational())
+		return;
+
+	if (source == lrng_noise_source_hw)
+		lrng_seed_hw = type;
+	else
+		lrng_seed_user = type;
+}
+
+void lrng_state_exseed_allow_all(void)
+{
+	lrng_state_exseed_set(lrng_noise_source_hw, true);
+	lrng_state_exseed_set(lrng_noise_source_user, true);
+}
+
+/************************ LRNG user output interfaces *************************/
+
+ssize_t lrng_read_seed(char __user *buf, size_t nbytes, unsigned int flags)
+{
+	ssize_t ret = 0;
+	u64 t[(sizeof(struct entropy_buf) + 3 * sizeof(u64) - 1) / sizeof(u64)];
+
+	memset(t, 0, sizeof(t));
+	ret = lrng_get_seed(t, min_t(size_t, nbytes, sizeof(t)), flags);
+	if (ret == -EMSGSIZE && copy_to_user(buf, t, sizeof(u64))) {
+		ret = -EFAULT;
+	} else if (ret > 0 && copy_to_user(buf, t, ret)) {
+		ret = -EFAULT;
+	}
+	memzero_explicit(t, sizeof(t));
+
+	return ret;
+}
+
+ssize_t lrng_read_common(char __user *buf, size_t nbytes, bool pr)
+{
+	ssize_t ret = 0;
+	u8 tmpbuf[LRNG_DRNG_BLOCKSIZE] __aligned(LRNG_KCAPI_ALIGN);
+	u8 *tmp_large = NULL, *tmp = tmpbuf;
+	u32 tmplen = sizeof(tmpbuf);
+
+	if (nbytes == 0)
+		return 0;
+
+	/*
+	 * Satisfy large read requests -- as the common case are smaller
+	 * request sizes, such as 16 or 32 bytes, avoid a kmalloc overhead for
+	 * those by using the stack variable of tmpbuf.
+	 */
+	if (!CONFIG_BASE_SMALL && (nbytes > sizeof(tmpbuf))) {
+		tmplen = min_t(u32, nbytes, LRNG_DRNG_MAX_REQSIZE);
+		tmp_large = kmalloc(tmplen + LRNG_KCAPI_ALIGN, GFP_KERNEL);
+		if (!tmp_large)
+			tmplen = sizeof(tmpbuf);
+		else
+			tmp = PTR_ALIGN(tmp_large, LRNG_KCAPI_ALIGN);
+	}
+
+	while (nbytes) {
+		u32 todo = min_t(u32, nbytes, tmplen);
+		int rc = 0;
+
+		/* Reschedule if we received a large request. */
+		if ((tmp_large) && need_resched()) {
+			if (signal_pending(current)) {
+				if (ret == 0)
+					ret = -ERESTARTSYS;
+				break;
+			}
+			schedule();
+		}
+
+		rc = lrng_drng_get_sleep(tmp, todo, pr);
+		if (rc <= 0) {
+			if (rc < 0)
+				ret = rc;
+			break;
+		}
+		if (copy_to_user(buf, tmp, rc)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		nbytes -= rc;
+		buf += rc;
+		ret += rc;
+	}
+
+	/* Wipe data just returned from memory */
+	if (tmp_large)
+		kfree_sensitive(tmp_large);
+	else
+		memzero_explicit(tmpbuf, sizeof(tmpbuf));
+
+	return ret;
+}
+
+ssize_t lrng_read_common_block(int nonblock, int pr,
+			       char __user *buf, size_t nbytes)
+{
+	int ret;
+
+	if (nbytes == 0)
+		return 0;
+
+	ret = lrng_drng_sleep_while_nonoperational(nonblock);
+	if (ret)
+		return ret;
+
+	return lrng_read_common(buf, nbytes, !!pr);
+}
+
+ssize_t lrng_drng_read_block(struct file *file, char __user *buf, size_t nbytes,
+			     loff_t *ppos)
+{
+	return lrng_read_common_block(file->f_flags & O_NONBLOCK,
+				      file->f_flags & O_SYNC, buf, nbytes);
+}
+
+__poll_t lrng_random_poll(struct file *file, poll_table *wait)
+{
+	__poll_t mask;
+
+	poll_wait(file, &lrng_init_wait, wait);
+	poll_wait(file, &lrng_write_wait, wait);
+	mask = 0;
+	if (lrng_state_operational())
+		mask |= EPOLLIN | EPOLLRDNORM;
+	if (lrng_need_entropy() ||
+	    lrng_state_exseed_allow(lrng_noise_source_user)) {
+		lrng_state_exseed_set(lrng_noise_source_user, false);
+		mask |= EPOLLOUT | EPOLLWRNORM;
+	}
+	return mask;
+}
+
+ssize_t lrng_drng_write_common(const char __user *buffer, size_t count,
+			       u32 entropy_bits)
+{
+	ssize_t ret = 0;
+	u8 buf[64] __aligned(LRNG_KCAPI_ALIGN);
+	const char __user *p = buffer;
+	u32 orig_entropy_bits = entropy_bits;
+
+	if (!lrng_get_available()) {
+		ret = lrng_drng_initalize();
+		if (!ret)
+			return ret;
+	}
+
+	count = min_t(size_t, count, INT_MAX);
+	while (count > 0) {
+		size_t bytes = min_t(size_t, count, sizeof(buf));
+		u32 ent = min_t(u32, bytes<<3, entropy_bits);
+
+		if (copy_from_user(&buf, p, bytes))
+			return -EFAULT;
+		/* Inject data into entropy pool */
+		lrng_pool_insert_aux(buf, bytes, ent);
+
+		count -= bytes;
+		p += bytes;
+		ret += bytes;
+		entropy_bits -= ent;
+
+		cond_resched();
+	}
+
+	/* Force reseed of DRNG during next data request. */
+	if (!orig_entropy_bits)
+		lrng_drng_force_reseed();
+
+	return ret;
+}
+
+ssize_t lrng_drng_write(struct file *file, const char __user *buffer,
+			size_t count, loff_t *ppos)
+{
+	return lrng_drng_write_common(buffer, count, 0);
+}
+
+long lrng_ioctl(struct file *f, unsigned int cmd, unsigned long arg)
+{
+	u32 digestsize_bits;
+	int size, ent_count_bits, ret;
+	int __user *p = (int __user *)arg;
+
+	switch (cmd) {
+	case RNDGETENTCNT:
+		ent_count_bits = lrng_avail_entropy_aux();
+		if (put_user(ent_count_bits, p))
+			return -EFAULT;
+		return 0;
+	case RNDADDTOENTCNT:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		if (get_user(ent_count_bits, p))
+			return -EFAULT;
+		ent_count_bits = (int)lrng_get_aux_ent() + ent_count_bits;
+		if (ent_count_bits < 0)
+			ent_count_bits = 0;
+		digestsize_bits = lrng_get_digestsize();
+		if (ent_count_bits > digestsize_bits)
+			ent_count_bits = digestsize_bits;
+		lrng_pool_set_entropy(ent_count_bits);
+		return 0;
+	case RNDADDENTROPY:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		if (get_user(ent_count_bits, p++))
+			return -EFAULT;
+		if (ent_count_bits < 0)
+			return -EINVAL;
+		if (get_user(size, p++))
+			return -EFAULT;
+		if (size < 0)
+			return -EINVAL;
+		/* there cannot be more entropy than data */
+		ent_count_bits = min(ent_count_bits, size<<3);
+		ret = lrng_drng_write_common((const char __user *)p, size,
+					     ent_count_bits);
+		return (ret < 0) ? ret : 0;
+	case RNDZAPENTCNT:
+	case RNDCLEARPOOL:
+		/* Clear the entropy pool counter. */
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		lrng_pool_set_entropy(0);
+		return 0;
+	case RNDRESEEDCRNG:
+		/*
+		 * We leave the capability check here since it is present
+		 * in the upstream's RNG implementation. Yet, user space
+		 * can trigger a reseed as easy as writing into /dev/random
+		 * or /dev/urandom where no privilege is needed.
+		 */
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		/* Force a reseed of all DRNGs */
+		lrng_drng_force_reseed();
+		return 0;
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL(lrng_ioctl);
+
+int lrng_fasync(int fd, struct file *filp, int on)
+{
+	return fasync_helper(fd, filp, on, &fasync);
+}
diff --git a/drivers/char/lrng/lrng_interface_dev_common.h b/drivers/char/lrng/lrng_interface_dev_common.h
new file mode 100644
index 000000000..9e6603ad8
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_dev_common.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_INTERFACE_DEV_COMMON_H
+#define _LRNG_INTERFACE_DEV_COMMON_H
+
+#include <linux/poll.h>
+#include <linux/wait.h>
+
+/******************* Upstream functions hooked into the LRNG ******************/
+enum lrng_external_noise_source {
+	lrng_noise_source_hw,
+	lrng_noise_source_user
+};
+
+#ifdef CONFIG_LRNG_COMMON_DEV_IF
+void lrng_writer_wakeup(void);
+void lrng_init_wakeup_dev(void);
+void lrng_state_exseed_set(enum lrng_external_noise_source source, bool type);
+void lrng_state_exseed_allow_all(void);
+#else /* CONFIG_LRNG_COMMON_DEV_IF */
+static inline void lrng_writer_wakeup(void) { }
+static inline void lrng_init_wakeup_dev(void) { }
+static inline void
+lrng_state_exseed_set(enum lrng_external_noise_source source, bool type) { }
+static inline void lrng_state_exseed_allow_all(void) { }
+#endif /* CONFIG_LRNG_COMMON_DEV_IF */
+
+/****** Downstream service functions to actual interface implementations ******/
+
+bool lrng_state_exseed_allow(enum lrng_external_noise_source source);
+int lrng_fasync(int fd, struct file *filp, int on);
+long lrng_ioctl(struct file *f, unsigned int cmd, unsigned long arg);
+ssize_t lrng_drng_write(struct file *file, const char __user *buffer,
+			size_t count, loff_t *ppos);
+ssize_t lrng_drng_write_common(const char __user *buffer, size_t count,
+			       u32 entropy_bits);
+__poll_t lrng_random_poll(struct file *file, poll_table *wait);
+ssize_t lrng_read_common_block(int nonblock, int pr,
+			       char __user *buf, size_t nbytes);
+ssize_t lrng_drng_read_block(struct file *file, char __user *buf, size_t nbytes,
+			     loff_t *ppos);
+ssize_t lrng_read_seed(char __user *buf, size_t nbytes, unsigned int flags);
+ssize_t lrng_read_common(char __user *buf, size_t nbytes, bool pr);
+bool lrng_need_entropy(void);
+
+extern struct wait_queue_head lrng_write_wait;
+
+#endif /* _LRNG_INTERFACE_DEV_COMMON_H */
diff --git a/drivers/char/lrng/lrng_interface_hwrand.c b/drivers/char/lrng/lrng_interface_hwrand.c
new file mode 100644
index 000000000..e841eea13
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_hwrand.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG interface with the HW-Random framework
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#include <linux/lrng.h>
+#include <linux/hw_random.h>
+#include <linux/module.h>
+
+static int lrng_hwrand_if_random(struct hwrng *rng, void *buf, size_t max,
+				 bool wait)
+{
+	/*
+	 * lrng_get_random_bytes_full not called as we cannot block.
+	 *
+	 * Note: We should either adjust .quality below depending on
+	 * rng_is_initialized() or block here, but neither is not supported by
+	 * the hw_rand framework.
+	 */
+	lrng_get_random_bytes(buf, max);
+	return (int)max;
+}
+
+static struct hwrng lrng_hwrand = {
+	.name		= "lrng",
+	.init		= NULL,
+	.cleanup	= NULL,
+	.read		= lrng_hwrand_if_random,
+
+	/*
+	 * We set .quality only in case the LRNG does not provide the common
+	 * interfaces or does not use the legacy RNG as entropy source. This
+	 * shall avoid that the LRNG automatically spawns the hw_rand
+	 * framework's hwrng kernel thread to feed data into
+	 * add_hwgenerator_randomness. When the LRNG implements the common
+	 * interfaces, this function feeds the data directly into the LRNG.
+	 * If the LRNG uses the legacy RNG as entropy source,
+	 * add_hwgenerator_randomness is implemented by the legacy RNG, but
+	 * still eventually feeds the data into the LRNG. We should avoid such
+	 * circular loops.
+	 *
+	 * We can specify full entropy here, because the LRNG is designed
+	 * to provide full entropy.
+	 */
+#if !defined(CONFIG_LRNG_RANDOM_IF) && \
+    !defined(CONFIG_LRNG_KERNEL_RNG)
+	.quality	= 1024,
+#endif
+};
+
+static int __init lrng_hwrand_if_mod_init(void)
+{
+	return hwrng_register(&lrng_hwrand);
+}
+
+static void __exit lrng_hwrand_if_mod_exit(void)
+{
+	hwrng_unregister(&lrng_hwrand);
+}
+
+module_init(lrng_hwrand_if_mod_init);
+module_exit(lrng_hwrand_if_mod_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
+MODULE_DESCRIPTION("Entropy Source and DRNG Manager HW-Random Interface");
diff --git a/drivers/char/lrng/lrng_interface_kcapi.c b/drivers/char/lrng/lrng_interface_kcapi.c
new file mode 100644
index 000000000..4cb511f80
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_kcapi.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG interface with the RNG framework of the kernel crypto API
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#include <linux/lrng.h>
+#include <linux/module.h>
+#include <crypto/internal/rng.h>
+
+#include "lrng_drng_mgr.h"
+#include "lrng_es_aux.h"
+
+static int lrng_kcapi_if_init(struct crypto_tfm *tfm)
+{
+	return 0;
+}
+
+static void lrng_kcapi_if_cleanup(struct crypto_tfm *tfm) { }
+
+static int lrng_kcapi_if_reseed(const u8 *src, unsigned int slen)
+{
+	int ret;
+
+	if (!slen)
+		return 0;
+
+	/* Insert caller-provided data without crediting entropy */
+	ret = lrng_pool_insert_aux((u8 *)src, slen, 0);
+	if (ret)
+		return ret;
+
+	/* Make sure the new data is immediately available to DRNG */
+	lrng_drng_force_reseed();
+
+	return 0;
+}
+
+static int lrng_kcapi_if_random(struct crypto_rng *tfm,
+				const u8 *src, unsigned int slen,
+				u8 *rdata, unsigned int dlen)
+{
+	int ret = lrng_kcapi_if_reseed(src, slen);
+
+	if (!ret)
+		lrng_get_random_bytes_full(rdata, dlen);
+
+	return ret;
+}
+
+static int lrng_kcapi_if_reset(struct crypto_rng *tfm,
+			       const u8 *seed, unsigned int slen)
+{
+	return lrng_kcapi_if_reseed(seed, slen);
+}
+
+static struct rng_alg lrng_alg = {
+	.generate		= lrng_kcapi_if_random,
+	.seed			= lrng_kcapi_if_reset,
+	.seedsize		= 0,
+	.base			= {
+		.cra_name               = "stdrng",
+		.cra_driver_name        = "lrng",
+		.cra_priority           = 500,
+		.cra_ctxsize            = 0,
+		.cra_module             = THIS_MODULE,
+		.cra_init               = lrng_kcapi_if_init,
+		.cra_exit               = lrng_kcapi_if_cleanup,
+
+	}
+};
+
+#ifdef CONFIG_LRNG_DRNG_ATOMIC
+static int lrng_kcapi_if_random_atomic(struct crypto_rng *tfm,
+				       const u8 *src, unsigned int slen,
+				       u8 *rdata, unsigned int dlen)
+{
+	int ret = lrng_kcapi_if_reseed(src, slen);
+
+	if (!ret)
+		lrng_get_random_bytes(rdata, dlen);
+
+	return ret;
+}
+
+static struct rng_alg lrng_alg_atomic = {
+	.generate		= lrng_kcapi_if_random_atomic,
+	.seed			= lrng_kcapi_if_reset,
+	.seedsize		= 0,
+	.base			= {
+		.cra_name               = "lrng_atomic",
+		.cra_driver_name        = "lrng_atomic",
+		.cra_priority           = 100,
+		.cra_ctxsize            = 0,
+		.cra_module             = THIS_MODULE,
+		.cra_init               = lrng_kcapi_if_init,
+		.cra_exit               = lrng_kcapi_if_cleanup,
+
+	}
+};
+#endif /* CONFIG_LRNG_DRNG_ATOMIC */
+
+static int __init lrng_kcapi_if_mod_init(void)
+{
+	return
+#ifdef CONFIG_LRNG_DRNG_ATOMIC
+	       crypto_register_rng(&lrng_alg_atomic) ?:
+#endif
+	       crypto_register_rng(&lrng_alg);
+}
+
+static void __exit lrng_kcapi_if_mod_exit(void)
+{
+	crypto_unregister_rng(&lrng_alg);
+#ifdef CONFIG_LRNG_DRNG_ATOMIC
+	crypto_unregister_rng(&lrng_alg_atomic);
+#endif
+}
+
+module_init(lrng_kcapi_if_mod_init);
+module_exit(lrng_kcapi_if_mod_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
+MODULE_DESCRIPTION("Entropy Source and DRNG Manager kernel crypto API RNG framework interface");
+MODULE_ALIAS_CRYPTO("lrng");
+MODULE_ALIAS_CRYPTO("lrng_atomic");
+MODULE_ALIAS_CRYPTO("stdrng");
diff --git a/drivers/char/lrng/lrng_interface_random_kernel.c b/drivers/char/lrng/lrng_interface_random_kernel.c
new file mode 100644
index 000000000..fabf2109c
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_random_kernel.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Kernel space interfaces API/ABI compliant to linux/random.h
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/blkdev.h>
+#include <linux/hw_random.h>
+#include <linux/kthread.h>
+#include <linux/lrng.h>
+#include <linux/random.h>
+
+#include "lrng_es_aux.h"
+#include "lrng_es_irq.h"
+#include "lrng_es_mgr.h"
+#include "lrng_interface_dev_common.h"
+#include "lrng_interface_random_kernel.h"
+
+static ATOMIC_NOTIFIER_HEAD(random_ready_notifier);
+
+/********************************** Helper ***********************************/
+
+static bool lrng_trust_bootloader __initdata =
+	IS_ENABLED(CONFIG_RANDOM_TRUST_BOOTLOADER);
+
+static int __init lrng_parse_trust_bootloader(char *arg)
+{
+	return kstrtobool(arg, &lrng_trust_bootloader);
+}
+early_param("random.trust_bootloader", lrng_parse_trust_bootloader);
+
+void __init random_init_early(const char *command_line)
+{
+	lrng_rand_initialize_early();
+	lrng_pool_insert_aux(command_line, strlen(command_line), 0);
+}
+
+void __init random_init(void)
+{
+	lrng_rand_initialize();
+}
+
+/*
+ * Add a callback function that will be invoked when the LRNG is initialised,
+ * or immediately if it already has been. Only use this is you are absolutely
+ * sure it is required. Most users should instead be able to test
+ * `rng_is_initialized()` on demand, or make use of `get_random_bytes_wait()`.
+ */
+int __cold execute_with_initialized_rng(struct notifier_block *nb)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&random_ready_notifier.lock, flags);
+	if (rng_is_initialized())
+		nb->notifier_call(nb, 0, NULL);
+	else
+		ret = raw_notifier_chain_register(
+			(struct raw_notifier_head *)&random_ready_notifier.head,
+			nb);
+	spin_unlock_irqrestore(&random_ready_notifier.lock, flags);
+	return ret;
+}
+
+void lrng_kick_random_ready(void)
+{
+	atomic_notifier_call_chain(&random_ready_notifier, 0, NULL);
+}
+
+/************************ LRNG kernel input interfaces ************************/
+
+/*
+ * add_hwgenerator_randomness() - Interface for in-kernel drivers of true
+ * hardware RNGs.
+ *
+ * Those devices may produce endless random bits and will be throttled
+ * when our pool is full.
+ *
+ * @buffer: buffer holding the entropic data from HW noise sources to be used to
+ *	    insert into entropy pool.
+ * @count: length of buffer
+ * @entropy_bits: amount of entropy in buffer (value is in bits)
+ */
+void add_hwgenerator_randomness(const void *buffer, size_t count,
+				size_t entropy_bits, bool sleep_after)
+{
+	/*
+	 * Suspend writing if we are fully loaded with entropy or if caller
+	 * did not provide any entropy. We'll be woken up again once below
+	 * lrng_write_wakeup_thresh, or when the calling thread is about to
+	 * terminate.
+	 */
+	wait_event_interruptible(lrng_write_wait,
+				(lrng_need_entropy() && entropy_bits) ||
+				lrng_state_exseed_allow(lrng_noise_source_hw) ||
+				!sleep_after ||
+				kthread_should_stop());
+	lrng_state_exseed_set(lrng_noise_source_hw, false);
+	lrng_pool_insert_aux(buffer, count, entropy_bits);
+}
+EXPORT_SYMBOL_GPL(add_hwgenerator_randomness);
+
+/*
+ * add_bootloader_randomness() - Handle random seed passed by bootloader.
+ *
+ * If the seed is trustworthy, it would be regarded as hardware RNGs. Otherwise
+ * it would be regarded as device data.
+ * The decision is controlled by CONFIG_RANDOM_TRUST_BOOTLOADER.
+ *
+ * @buf: buffer holding the entropic data from HW noise sources to be used to
+ *	 insert into entropy pool.
+ * @size: length of buffer
+ */
+void __init add_bootloader_randomness(const void *buf, size_t size)
+{
+	lrng_pool_insert_aux(buf, size, lrng_trust_bootloader ? size * 8 : 0);
+}
+
+/*
+ * Callback for HID layer -- use the HID event values to stir the entropy pool
+ */
+void add_input_randomness(unsigned int type, unsigned int code,
+			  unsigned int value)
+{
+	static unsigned char last_value;
+
+	/* ignore autorepeat and the like */
+	if (value == last_value)
+		return;
+
+	last_value = value;
+
+	lrng_irq_array_add_u32((type << 4) ^ code ^ (code >> 4) ^ value);
+}
+EXPORT_SYMBOL_GPL(add_input_randomness);
+
+/*
+ * add_device_randomness() - Add device- or boot-specific data to the entropy
+ * pool to help initialize it.
+ *
+ * None of this adds any entropy; it is meant to avoid the problem of
+ * the entropy pool having similar initial state across largely
+ * identical devices.
+ *
+ * @buf: buffer holding the entropic data from HW noise sources to be used to
+ *	 insert into entropy pool.
+ * @size: length of buffer
+ */
+void add_device_randomness(const void *buf, size_t size)
+{
+	lrng_pool_insert_aux((u8 *)buf, size, 0);
+}
+EXPORT_SYMBOL(add_device_randomness);
+
+#ifdef CONFIG_BLOCK
+void rand_initialize_disk(struct gendisk *disk) { }
+void add_disk_randomness(struct gendisk *disk) { }
+EXPORT_SYMBOL(add_disk_randomness);
+#endif
+
+#ifndef CONFIG_LRNG_IRQ
+void add_interrupt_randomness(int irq) { }
+EXPORT_SYMBOL(add_interrupt_randomness);
+#endif
+
+#if IS_ENABLED(CONFIG_VMGENID)
+static BLOCKING_NOTIFIER_HEAD(lrng_vmfork_chain);
+
+/*
+ * Handle a new unique VM ID, which is unique, not secret, so we
+ * don't credit it, but we do immediately force a reseed after so
+ * that it's used by the crng posthaste.
+ */
+void add_vmfork_randomness(const void *unique_vm_id, size_t size)
+{
+	add_device_randomness(unique_vm_id, size);
+	if (lrng_state_operational())
+		lrng_drng_force_reseed();
+	blocking_notifier_call_chain(&lrng_vmfork_chain, 0, NULL);
+}
+#if IS_MODULE(CONFIG_VMGENID)
+EXPORT_SYMBOL_GPL(add_vmfork_randomness);
+#endif
+
+int register_random_vmfork_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&lrng_vmfork_chain, nb);
+}
+EXPORT_SYMBOL_GPL(register_random_vmfork_notifier);
+
+int unregister_random_vmfork_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&lrng_vmfork_chain, nb);
+}
+EXPORT_SYMBOL_GPL(unregister_random_vmfork_notifier);
+#endif
+
+/*********************** LRNG kernel output interfaces ************************/
+
+/*
+ * get_random_bytes() - Provider of cryptographic strong random numbers for
+ * kernel-internal usage.
+ *
+ * This function is appropriate for all in-kernel use cases. However,
+ * it will always use the ChaCha20 DRNG.
+ *
+ * @buf: buffer to store the random bytes
+ * @nbytes: size of the buffer
+ */
+void get_random_bytes(void *buf, size_t nbytes)
+{
+	lrng_get_random_bytes(buf, nbytes);
+}
+EXPORT_SYMBOL(get_random_bytes);
+
+/*
+ * wait_for_random_bytes() - Wait for the LRNG to be seeded and thus
+ * guaranteed to supply cryptographically secure random numbers.
+ *
+ * This applies to: the /dev/urandom device, the get_random_bytes function,
+ * and the get_random_{u32,u64,int,long} family of functions. Using any of
+ * these functions without first calling this function forfeits the guarantee
+ * of security.
+ *
+ * Return:
+ * * 0 if the LRNG has been seeded.
+ * * -ERESTARTSYS if the function was interrupted by a signal.
+ */
+int wait_for_random_bytes(void)
+{
+	return lrng_drng_sleep_while_non_min_seeded();
+}
+EXPORT_SYMBOL(wait_for_random_bytes);
+
+/*
+ * Returns whether or not the LRNG has been seeded.
+ *
+ * Returns: true if the urandom pool has been seeded.
+ *          false if the urandom pool has not been seeded.
+ */
+bool rng_is_initialized(void)
+{
+	return lrng_state_operational();
+}
+EXPORT_SYMBOL(rng_is_initialized);
diff --git a/drivers/char/lrng/lrng_interface_random_kernel.h b/drivers/char/lrng/lrng_interface_random_kernel.h
new file mode 100644
index 000000000..ea2b5be8d
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_random_kernel.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_INTERFACE_RANDOM_H
+#define _LRNG_INTERFACE_RANDOM_H
+
+#ifdef CONFIG_LRNG_RANDOM_IF
+void invalidate_batched_entropy(void);
+void lrng_kick_random_ready(void);
+#else /* CONFIG_LRNG_RANDOM_IF */
+static inline void invalidate_batched_entropy(void) { }
+static inline void lrng_kick_random_ready(void) { }
+#endif /* CONFIG_LRNG_RANDOM_IF */
+
+#endif /* _LRNG_INTERFACE_RANDOM_H */
diff --git a/drivers/char/lrng/lrng_interface_random_user.c b/drivers/char/lrng/lrng_interface_random_user.c
new file mode 100644
index 000000000..d12e88380
--- /dev/null
+++ b/drivers/char/lrng/lrng_interface_random_user.c
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG Common user space interfaces compliant to random(4), random(7) and
+ * getrandom(2) man pages.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/random.h>
+#include <linux/syscalls.h>
+
+#include "lrng_es_mgr.h"
+#include "lrng_interface_dev_common.h"
+
+static ssize_t lrng_drng_read(struct file *file, char __user *buf,
+			      size_t nbytes, loff_t *ppos)
+{
+	if (!lrng_state_min_seeded())
+		pr_notice_ratelimited("%s - use of insufficiently seeded DRNG (%zu bytes read)\n",
+				      current->comm, nbytes);
+	else if (!lrng_state_operational())
+		pr_debug_ratelimited("%s - use of not fully seeded DRNG (%zu bytes read)\n",
+				     current->comm, nbytes);
+
+	return lrng_read_common(buf, nbytes, false);
+}
+
+const struct file_operations random_fops = {
+	.read  = lrng_drng_read_block,
+	.write = lrng_drng_write,
+	.poll  = lrng_random_poll,
+	.unlocked_ioctl = lrng_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
+	.fasync = lrng_fasync,
+	.llseek = noop_llseek,
+};
+
+const struct file_operations urandom_fops = {
+	.read  = lrng_drng_read,
+	.write = lrng_drng_write,
+	.unlocked_ioctl = lrng_ioctl,
+	.compat_ioctl = compat_ptr_ioctl,
+	.fasync = lrng_fasync,
+	.llseek = noop_llseek,
+};
+
+/*
+ * GRND_SEED
+ *
+ * This flag requests to provide the data directly from the entropy sources.
+ *
+ * The behavior of the call is exactly as outlined for the function
+ * lrng_get_seed in lrng.h.
+ */
+#define GRND_SEED		0x0010
+
+/*
+ * GRND_FULLY_SEEDED
+ *
+ * This flag indicates whether the caller wants to reseed a DRNG that is already
+ * fully seeded. See esdm_get_seed in lrng.h for details.
+ */
+#define GRND_FULLY_SEEDED	0x0020
+
+SYSCALL_DEFINE3(getrandom, char __user *, buf, size_t, count,
+		unsigned int, flags)
+{
+	if (flags & ~(GRND_NONBLOCK|GRND_RANDOM|GRND_INSECURE|
+		      GRND_SEED|GRND_FULLY_SEEDED))
+		return -EINVAL;
+
+	/*
+	 * Requesting insecure and blocking randomness at the same time makes
+	 * no sense.
+	 */
+	if ((flags &
+	     (GRND_INSECURE|GRND_RANDOM)) == (GRND_INSECURE|GRND_RANDOM))
+		return -EINVAL;
+	if ((flags &
+	     (GRND_INSECURE|GRND_SEED)) == (GRND_INSECURE|GRND_SEED))
+		return -EINVAL;
+	if ((flags &
+	     (GRND_RANDOM|GRND_SEED)) == (GRND_RANDOM|GRND_SEED))
+		return -EINVAL;
+
+	if (count > INT_MAX)
+		count = INT_MAX;
+
+	if (flags & GRND_INSECURE) {
+		return lrng_drng_read(NULL, buf, count, NULL);
+	} else if (flags & GRND_SEED) {
+		unsigned int seed_flags = (flags & GRND_NONBLOCK) ?
+					  LRNG_GET_SEED_NONBLOCK : 0;
+
+		seed_flags |= (flags & GRND_FULLY_SEEDED) ?
+			      LRNG_GET_SEED_FULLY_SEEDED : 0;
+		return lrng_read_seed(buf, count, seed_flags);
+	}
+
+	return lrng_read_common_block(flags & GRND_NONBLOCK,
+				      flags & GRND_RANDOM, buf, count);
+}
diff --git a/drivers/char/lrng/lrng_numa.c b/drivers/char/lrng/lrng_numa.c
new file mode 100644
index 000000000..d74dd8df2
--- /dev/null
+++ b/drivers/char/lrng/lrng_numa.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG NUMA support
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <linux/slab.h>
+
+#include "lrng_drng_mgr.h"
+#include "lrng_es_irq.h"
+#include "lrng_es_mgr.h"
+#include "lrng_numa.h"
+#include "lrng_proc.h"
+
+static struct lrng_drng **lrng_drng __read_mostly = NULL;
+
+struct lrng_drng **lrng_drng_instances(void)
+{
+	/* counterpart to cmpxchg_release in _lrng_drngs_numa_alloc */
+	return READ_ONCE(lrng_drng);
+}
+
+/* Allocate the data structures for the per-NUMA node DRNGs */
+static void _lrng_drngs_numa_alloc(struct work_struct *work)
+{
+	struct lrng_drng **drngs;
+	struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+	u32 node;
+	bool init_drng_used = false;
+
+	mutex_lock(&lrng_crypto_cb_update);
+
+	/* per-NUMA-node DRNGs are already present */
+	if (lrng_drng)
+		goto unlock;
+
+	/* Make sure the initial DRNG is initialized and its drng_cb is set */
+	if (lrng_drng_initalize())
+		goto err;
+
+	drngs = kcalloc(nr_node_ids, sizeof(void *), GFP_KERNEL|__GFP_NOFAIL);
+	for_each_online_node(node) {
+		struct lrng_drng *drng;
+
+		if (!init_drng_used) {
+			drngs[node] = lrng_drng_init;
+			init_drng_used = true;
+			continue;
+		}
+
+		drng = kmalloc_node(sizeof(struct lrng_drng),
+				    GFP_KERNEL|__GFP_NOFAIL, node);
+		memset(drng, 0, sizeof(lrng_drng));
+
+		if (lrng_drng_alloc_common(drng, lrng_drng_init->drng_cb)) {
+			kfree(drng);
+			goto err;
+		}
+
+		drng->hash_cb = lrng_drng_init->hash_cb;
+		drng->hash = lrng_drng_init->hash_cb->hash_alloc();
+		if (IS_ERR(drng->hash)) {
+			lrng_drng_init->drng_cb->drng_dealloc(drng->drng);
+			kfree(drng);
+			goto err;
+		}
+
+		mutex_init(&drng->lock);
+		rwlock_init(&drng->hash_lock);
+
+		/*
+		 * No reseeding of NUMA DRNGs from previous DRNGs as this
+		 * would complicate the code. Let it simply reseed.
+		 */
+		drngs[node] = drng;
+
+		lrng_pool_inc_numa_node();
+		pr_info("DRNG and entropy pool read hash for NUMA node %d allocated\n",
+			node);
+	}
+
+	/* counterpart to READ_ONCE in lrng_drng_instances */
+	if (!cmpxchg_release(&lrng_drng, NULL, drngs)) {
+		lrng_pool_all_numa_nodes_seeded(false);
+		goto unlock;
+	}
+
+err:
+	for_each_online_node(node) {
+		struct lrng_drng *drng = drngs[node];
+
+		if (drng == lrng_drng_init)
+			continue;
+
+		if (drng) {
+			drng->hash_cb->hash_dealloc(drng->hash);
+			drng->drng_cb->drng_dealloc(drng->drng);
+			kfree(drng);
+		}
+	}
+	kfree(drngs);
+
+unlock:
+	mutex_unlock(&lrng_crypto_cb_update);
+}
+
+static DECLARE_WORK(lrng_drngs_numa_alloc_work, _lrng_drngs_numa_alloc);
+
+static void lrng_drngs_numa_alloc(void)
+{
+	schedule_work(&lrng_drngs_numa_alloc_work);
+}
+
+static int __init lrng_numa_init(void)
+{
+	lrng_drngs_numa_alloc();
+	return 0;
+}
+
+late_initcall(lrng_numa_init);
diff --git a/drivers/char/lrng/lrng_numa.h b/drivers/char/lrng/lrng_numa.h
new file mode 100644
index 000000000..dc8dff981
--- /dev/null
+++ b/drivers/char/lrng/lrng_numa.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_NUMA_H
+#define _LRNG_NUMA_H
+
+#ifdef CONFIG_NUMA
+struct lrng_drng **lrng_drng_instances(void);
+#else	/* CONFIG_NUMA */
+static inline struct lrng_drng **lrng_drng_instances(void) { return NULL; }
+#endif /* CONFIG_NUMA */
+
+#endif /* _LRNG_NUMA_H */
diff --git a/drivers/char/lrng/lrng_proc.c b/drivers/char/lrng/lrng_proc.c
new file mode 100644
index 000000000..a9c8d90c7
--- /dev/null
+++ b/drivers/char/lrng/lrng_proc.c
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG proc interfaces
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#include <linux/lrng.h>
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+
+#include "lrng_drng_mgr.h"
+#include "lrng_es_aux.h"
+#include "lrng_es_mgr.h"
+#include "lrng_proc.h"
+
+/* Number of online DRNGs */
+static u32 numa_drngs = 1;
+
+void lrng_pool_inc_numa_node(void)
+{
+	numa_drngs++;
+}
+
+static int lrng_proc_type_show(struct seq_file *m, void *v)
+{
+	struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+	unsigned char buf[270];
+	u32 i;
+
+	mutex_lock(&lrng_drng_init->lock);
+	snprintf(buf, sizeof(buf),
+		 "DRNG name: %s\n"
+		 "LRNG security strength in bits: %d\n"
+		 "Number of DRNG instances: %u\n"
+		 "Standards compliance: %sNTG.1 (2011%s)\n"
+		 "LRNG minimally seeded: %s\n"
+		 "LRNG fully seeded: %s\n"
+		 "LRNG entropy level: %u\n",
+		 lrng_drng_init->drng_cb->drng_name(),
+		 lrng_security_strength(),
+		 numa_drngs,
+		 lrng_sp80090c_compliant() ? "SP800-90C, " : "",
+		 lrng_ntg1_2022_compliant() ? " / 2022" : "",
+		 lrng_state_min_seeded() ? "true" : "false",
+		 lrng_state_fully_seeded() ? "true" : "false",
+		 lrng_avail_entropy());
+	seq_write(m, buf, strlen(buf));
+
+	for_each_lrng_es(i) {
+		snprintf(buf, sizeof(buf),
+			 "Entropy Source %u properties:\n"
+			 " Name: %s\n",
+			 i, lrng_es[i]->name);
+		seq_write(m, buf, strlen(buf));
+
+		buf[0] = '\0';
+		lrng_es[i]->state(buf, sizeof(buf));
+		seq_write(m, buf, strlen(buf));
+	}
+
+	mutex_unlock(&lrng_drng_init->lock);
+
+	return 0;
+}
+
+static int __init lrng_proc_type_init(void)
+{
+	proc_create_single("lrng_type", 0444, NULL, &lrng_proc_type_show);
+	return 0;
+}
+
+module_init(lrng_proc_type_init);
diff --git a/drivers/char/lrng/lrng_proc.h b/drivers/char/lrng/lrng_proc.h
new file mode 100644
index 000000000..c653274f1
--- /dev/null
+++ b/drivers/char/lrng/lrng_proc.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_PROC_H
+#define _LRNG_PROC_H
+
+#ifdef CONFIG_SYSCTL
+void lrng_pool_inc_numa_node(void);
+#else
+static inline void lrng_pool_inc_numa_node(void) { }
+#endif
+
+#endif /* _LRNG_PROC_H */
diff --git a/drivers/char/lrng/lrng_selftest.c b/drivers/char/lrng/lrng_selftest.c
new file mode 100644
index 000000000..15f1e4a2a
--- /dev/null
+++ b/drivers/char/lrng/lrng_selftest.c
@@ -0,0 +1,397 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG power-on and on-demand self-test
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+/*
+ * In addition to the self-tests below, the following LRNG components
+ * are covered with self-tests during regular operation:
+ *
+ * * power-on self-test: SP800-90A DRBG provided by the Linux kernel crypto API
+ * * power-on self-test: PRNG provided by the Linux kernel crypto API
+ * * runtime test: Raw noise source data testing including SP800-90B compliant
+ *		   tests when enabling CONFIG_LRNG_HEALTH_TESTS
+ *
+ * Additional developer tests present with LRNG code:
+ * * SP800-90B APT and RCT test enforcement validation when enabling
+ *   CONFIG_LRNG_APT_BROKEN or CONFIG_LRNG_RCT_BROKEN.
+ * * Collection of raw entropy from the interrupt noise source when enabling
+ *   CONFIG_LRNG_TESTING and pulling the data from the kernel with the provided
+ *   interface.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "lrng_drng_chacha20.h"
+#include "lrng_sha.h"
+
+#define LRNG_SELFTEST_PASSED		0
+#define LRNG_SEFLTEST_ERROR_TIME	(1 << 0)
+#define LRNG_SEFLTEST_ERROR_CHACHA20	(1 << 1)
+#define LRNG_SEFLTEST_ERROR_HASH	(1 << 2)
+#define LRNG_SEFLTEST_ERROR_GCD		(1 << 3)
+#define LRNG_SELFTEST_NOT_EXECUTED	0xffffffff
+
+#ifdef CONFIG_LRNG_TIMER_COMMON
+
+#include "lrng_es_timer_common.h"
+
+static u32 lrng_data_selftest_ptr = 0;
+static u32 lrng_data_selftest[LRNG_DATA_ARRAY_SIZE];
+
+static void lrng_data_process_selftest_insert(u32 time)
+{
+	u32 ptr = lrng_data_selftest_ptr++ & LRNG_DATA_WORD_MASK;
+	unsigned int array = lrng_data_idx2array(ptr);
+	unsigned int slot = lrng_data_idx2slot(ptr);
+
+	/* zeroization of slot to ensure the following OR adds the data */
+	lrng_data_selftest[array] &=
+		~(lrng_data_slot_val(0xffffffff & LRNG_DATA_SLOTSIZE_MASK,
+				     slot));
+	lrng_data_selftest[array] |=
+		lrng_data_slot_val(time & LRNG_DATA_SLOTSIZE_MASK, slot);
+}
+
+static void lrng_data_process_selftest_u32(u32 data)
+{
+	u32 pre_ptr, ptr, mask;
+	unsigned int pre_array;
+
+	/* Increment pointer by number of slots taken for input value */
+	lrng_data_selftest_ptr += LRNG_DATA_SLOTS_PER_UINT;
+
+	/* ptr to current unit */
+	ptr = lrng_data_selftest_ptr;
+
+	lrng_data_split_u32(&ptr, &pre_ptr, &mask);
+
+	/* MSB of data go into previous unit */
+	pre_array = lrng_data_idx2array(pre_ptr);
+	/* zeroization of slot to ensure the following OR adds the data */
+	lrng_data_selftest[pre_array] &= ~(0xffffffff & ~mask);
+	lrng_data_selftest[pre_array] |= data & ~mask;
+
+	/* LSB of data go into current unit */
+	lrng_data_selftest[lrng_data_idx2array(ptr)] = data & mask;
+}
+
+static unsigned int lrng_data_process_selftest(void)
+{
+	u32 time;
+	u32 idx_zero_compare = (0 << 0) | (1 << 8) | (2 << 16) | (3 << 24);
+	u32 idx_one_compare  = (4 << 0) | (5 << 8) | (6 << 16) | (7 << 24);
+	u32 idx_last_compare =
+		(((LRNG_DATA_NUM_VALUES - 4) & LRNG_DATA_SLOTSIZE_MASK) << 0)  |
+		(((LRNG_DATA_NUM_VALUES - 3) & LRNG_DATA_SLOTSIZE_MASK) << 8)  |
+		(((LRNG_DATA_NUM_VALUES - 2) & LRNG_DATA_SLOTSIZE_MASK) << 16) |
+		(((LRNG_DATA_NUM_VALUES - 1) & LRNG_DATA_SLOTSIZE_MASK) << 24);
+
+	(void)idx_one_compare;
+
+	/* "poison" the array to verify the operation of the zeroization */
+	lrng_data_selftest[0] = 0xffffffff;
+	lrng_data_selftest[1] = 0xffffffff;
+
+	lrng_data_process_selftest_insert(0);
+	/*
+	 * Note, when using lrng_data_process_u32() on unaligned ptr,
+	 * the first slots will go into next word, and the last slots go
+	 * into the previous word.
+	 */
+	lrng_data_process_selftest_u32((4 << 0) | (1 << 8) | (2 << 16) |
+				       (3 << 24));
+	lrng_data_process_selftest_insert(5);
+	lrng_data_process_selftest_insert(6);
+	lrng_data_process_selftest_insert(7);
+
+	if ((lrng_data_selftest[0] != idx_zero_compare) ||
+	    (lrng_data_selftest[1] != idx_one_compare))
+		goto err;
+
+	/* Reset for next test */
+	lrng_data_selftest[0] = 0;
+	lrng_data_selftest[1] = 0;
+	lrng_data_selftest_ptr = 0;
+
+	for (time = 0; time < LRNG_DATA_NUM_VALUES; time++)
+		lrng_data_process_selftest_insert(time);
+
+	if ((lrng_data_selftest[0] != idx_zero_compare) ||
+	    (lrng_data_selftest[1] != idx_one_compare)  ||
+	    (lrng_data_selftest[LRNG_DATA_ARRAY_SIZE - 1] != idx_last_compare))
+		goto err;
+
+	return LRNG_SELFTEST_PASSED;
+
+err:
+	pr_err("LRNG data array self-test FAILED\n");
+	return LRNG_SEFLTEST_ERROR_TIME;
+}
+
+static unsigned int lrng_gcd_selftest(void)
+{
+	u32 history[10];
+	unsigned int i;
+
+#define LRNG_GCD_SELFTEST 3
+	for (i = 0; i < ARRAY_SIZE(history); i++)
+		history[i] = i * LRNG_GCD_SELFTEST;
+
+	if (lrng_gcd_analyze(history, ARRAY_SIZE(history)) == LRNG_GCD_SELFTEST)
+		return LRNG_SELFTEST_PASSED;
+
+	pr_err("LRNG GCD self-test FAILED\n");
+	return LRNG_SEFLTEST_ERROR_GCD;
+}
+
+#else /* CONFIG_LRNG_TIMER_COMMON */
+
+static unsigned int lrng_data_process_selftest(void)
+{
+	return LRNG_SELFTEST_PASSED;
+}
+
+static unsigned int lrng_gcd_selftest(void)
+{
+	return LRNG_SELFTEST_PASSED;
+}
+
+#endif /* CONFIG_LRNG_TIMER_COMMON */
+
+/* The test vectors are taken from crypto/testmgr.h */
+static unsigned int lrng_hash_selftest(void)
+{
+	SHASH_DESC_ON_STACK(shash, NULL);
+	const struct lrng_hash_cb *hash_cb = &lrng_sha_hash_cb;
+	static const u8 lrng_hash_selftest_result[] =
+#ifdef CONFIG_CRYPTO_LIB_SHA256
+		{ 0xba, 0x78, 0x16, 0xbf, 0x8f, 0x01, 0xcf, 0xea,
+		  0x41, 0x41, 0x40, 0xde, 0x5d, 0xae, 0x22, 0x23,
+		  0xb0, 0x03, 0x61, 0xa3, 0x96, 0x17, 0x7a, 0x9c,
+		  0xb4, 0x10, 0xff, 0x61, 0xf2, 0x00, 0x15, 0xad };
+#else /* CONFIG_CRYPTO_LIB_SHA256 */
+		{ 0xa9, 0x99, 0x3e, 0x36, 0x47, 0x06, 0x81, 0x6a, 0xba, 0x3e,
+		  0x25, 0x71, 0x78, 0x50, 0xc2, 0x6c, 0x9c, 0xd0, 0xd8, 0x9d };
+#endif /* CONFIG_CRYPTO_LIB_SHA256 */
+	static const u8 hash_input[] = { 0x61, 0x62, 0x63 }; /* "abc" */
+	u8 digest[sizeof(lrng_hash_selftest_result)] __aligned(sizeof(u32));
+
+	if (sizeof(digest) != hash_cb->hash_digestsize(NULL))
+		return LRNG_SEFLTEST_ERROR_HASH;
+
+	if (!hash_cb->hash_init(shash, NULL) &&
+	    !hash_cb->hash_update(shash, hash_input,
+					 sizeof(hash_input)) &&
+	    !hash_cb->hash_final(shash, digest) &&
+	    !memcmp(digest, lrng_hash_selftest_result, sizeof(digest)))
+		return 0;
+
+	pr_err("LRNG %s Hash self-test FAILED\n", hash_cb->hash_name());
+	return LRNG_SEFLTEST_ERROR_HASH;
+}
+
+#ifdef CONFIG_LRNG_DRNG_CHACHA20
+
+static void lrng_selftest_bswap32(u32 *ptr, u32 words)
+{
+	u32 i;
+
+	/* Byte-swap data which is an LE representation */
+	for (i = 0; i < words; i++) {
+		__le32 *p = (__le32 *)ptr;
+
+		*p = cpu_to_le32(*ptr);
+		ptr++;
+	}
+}
+
+/*
+ * The test vectors were generated using the ChaCha20 DRNG from
+ * https://www.chronox.de/chacha20.html
+ */
+static unsigned int lrng_chacha20_drng_selftest(void)
+{
+	const struct lrng_drng_cb *drng_cb = &lrng_cc20_drng_cb;
+	u8 seed[CHACHA_KEY_SIZE * 2] = {
+		0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+		0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+		0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+		0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+		0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+		0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+		0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+		0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
+	};
+	struct chacha20_block chacha20;
+	int ret;
+	u8 outbuf[CHACHA_KEY_SIZE * 2] __aligned(sizeof(u32));
+
+	/*
+	 * Expected result when ChaCha20 DRNG state is zero:
+	 *	* constants are set to "expand 32-byte k"
+	 *	* remaining state is 0
+	 * and pulling one half ChaCha20 DRNG block.
+	 */
+	static const u8 expected_halfblock[CHACHA_KEY_SIZE] = {
+		0x76, 0xb8, 0xe0, 0xad, 0xa0, 0xf1, 0x3d, 0x90,
+		0x40, 0x5d, 0x6a, 0xe5, 0x53, 0x86, 0xbd, 0x28,
+		0xbd, 0xd2, 0x19, 0xb8, 0xa0, 0x8d, 0xed, 0x1a,
+		0xa8, 0x36, 0xef, 0xcc, 0x8b, 0x77, 0x0d, 0xc7 };
+
+	/*
+	 * Expected result when ChaCha20 DRNG state is zero:
+	 *	* constants are set to "expand 32-byte k"
+	 *	* remaining state is 0
+	 * followed by a reseed with two keyblocks
+	 *	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+	 *	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+	 *	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+	 *	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+	 *	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+	 *	0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+	 *	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+	 *	0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f
+	 * and pulling one ChaCha20 DRNG block.
+	 */
+	static const u8 expected_oneblock[CHACHA_KEY_SIZE * 2] = {
+		0xe3, 0xb0, 0x8a, 0xcc, 0x34, 0xc3, 0x17, 0x0e,
+		0xc3, 0xd8, 0xc3, 0x40, 0xe7, 0x73, 0xe9, 0x0d,
+		0xd1, 0x62, 0xa3, 0x5d, 0x7d, 0xf2, 0xf1, 0x4a,
+		0x24, 0x42, 0xb7, 0x1e, 0xb0, 0x05, 0x17, 0x07,
+		0xb9, 0x35, 0x10, 0x69, 0x8b, 0x46, 0xfb, 0x51,
+		0xe9, 0x91, 0x3f, 0x46, 0xf2, 0x4d, 0xea, 0xd0,
+		0x81, 0xc1, 0x1b, 0xa9, 0x5d, 0x52, 0x91, 0x5f,
+		0xcd, 0xdc, 0xc6, 0xd6, 0xc3, 0x7c, 0x50, 0x23 };
+
+	/*
+	 * Expected result when ChaCha20 DRNG state is zero:
+	 *	* constants are set to "expand 32-byte k"
+	 *	* remaining state is 0
+	 * followed by a reseed with one key block plus one byte
+	 *	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+	 *	0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+	 *	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+	 *	0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
+	 *	0x20
+	 * and pulling less than one ChaCha20 DRNG block.
+	 */
+	static const u8 expected_block_nonalinged[CHACHA_KEY_SIZE + 4] = {
+		0x9c, 0xfc, 0x5e, 0x31, 0x21, 0x62, 0x11, 0x85,
+		0xd3, 0x77, 0xd3, 0x69, 0x0f, 0xa8, 0x16, 0x55,
+		0xb4, 0x4c, 0xf6, 0x52, 0xf3, 0xa8, 0x37, 0x99,
+		0x38, 0x76, 0xa0, 0x66, 0xec, 0xbb, 0xce, 0xa9,
+		0x9c, 0x95, 0xa1, 0xfd };
+
+	BUILD_BUG_ON(sizeof(seed) % sizeof(u32));
+
+	memset(&chacha20, 0, sizeof(chacha20));
+	lrng_cc20_init_rfc7539(&chacha20);
+	lrng_selftest_bswap32((u32 *)seed, sizeof(seed) / sizeof(u32));
+
+	/* Generate with zero state */
+	ret = drng_cb->drng_generate(&chacha20, outbuf,
+				     sizeof(expected_halfblock));
+	if (ret != sizeof(expected_halfblock))
+		goto err;
+	if (memcmp(outbuf, expected_halfblock, sizeof(expected_halfblock)))
+		goto err;
+
+	/* Clear state of DRNG */
+	memset(&chacha20.key.u[0], 0, 48);
+
+	/* Reseed with 2 key blocks */
+	ret = drng_cb->drng_seed(&chacha20, seed, sizeof(expected_oneblock));
+	if (ret < 0)
+		goto err;
+	ret = drng_cb->drng_generate(&chacha20, outbuf,
+				     sizeof(expected_oneblock));
+	if (ret != sizeof(expected_oneblock))
+		goto err;
+	if (memcmp(outbuf, expected_oneblock, sizeof(expected_oneblock)))
+		goto err;
+
+	/* Clear state of DRNG */
+	memset(&chacha20.key.u[0], 0, 48);
+
+	/* Reseed with 1 key block and one byte */
+	ret = drng_cb->drng_seed(&chacha20, seed,
+				 sizeof(expected_block_nonalinged));
+	if (ret < 0)
+		goto err;
+	ret = drng_cb->drng_generate(&chacha20, outbuf,
+				     sizeof(expected_block_nonalinged));
+	if (ret != sizeof(expected_block_nonalinged))
+		goto err;
+	if (memcmp(outbuf, expected_block_nonalinged,
+		   sizeof(expected_block_nonalinged)))
+		goto err;
+
+	return LRNG_SELFTEST_PASSED;
+
+err:
+	pr_err("LRNG ChaCha20 DRNG self-test FAILED\n");
+	return LRNG_SEFLTEST_ERROR_CHACHA20;
+}
+
+#else /* CONFIG_LRNG_DRNG_CHACHA20 */
+
+static unsigned int lrng_chacha20_drng_selftest(void)
+{
+	return LRNG_SELFTEST_PASSED;
+}
+
+#endif /* CONFIG_LRNG_DRNG_CHACHA20 */
+
+static unsigned int lrng_selftest_status = LRNG_SELFTEST_NOT_EXECUTED;
+
+static int lrng_selftest(void)
+{
+	unsigned int ret = lrng_data_process_selftest();
+
+	ret |= lrng_chacha20_drng_selftest();
+	ret |= lrng_hash_selftest();
+	ret |= lrng_gcd_selftest();
+
+	if (ret) {
+		if (IS_ENABLED(CONFIG_LRNG_SELFTEST_PANIC))
+			panic("LRNG self-tests failed: %u\n", ret);
+	} else {
+		pr_info("LRNG self-tests passed\n");
+	}
+
+	lrng_selftest_status = ret;
+
+	if (lrng_selftest_status)
+		return -EFAULT;
+	return 0;
+}
+
+#ifdef CONFIG_SYSFS
+/* Re-perform self-test when any value is written to the sysfs file. */
+static int lrng_selftest_sysfs_set(const char *val,
+				   const struct kernel_param *kp)
+{
+	return lrng_selftest();
+}
+
+static const struct kernel_param_ops lrng_selftest_sysfs = {
+	.set = lrng_selftest_sysfs_set,
+	.get = param_get_uint,
+};
+module_param_cb(selftest_status, &lrng_selftest_sysfs, &lrng_selftest_status,
+		0644);
+#endif	/* CONFIG_SYSFS */
+
+static int __init lrng_selftest_init(void)
+{
+	return lrng_selftest();
+}
+
+module_init(lrng_selftest_init);
diff --git a/drivers/char/lrng/lrng_sha.h b/drivers/char/lrng/lrng_sha.h
new file mode 100644
index 000000000..d2f134f54
--- /dev/null
+++ b/drivers/char/lrng/lrng_sha.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * LRNG SHA definition usable in atomic contexts right from the start of the
+ * kernel.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_SHA_H
+#define _LRNG_SHA_H
+
+extern const struct lrng_hash_cb lrng_sha_hash_cb;
+
+#endif /* _LRNG_SHA_H */
diff --git a/drivers/char/lrng/lrng_sha1.c b/drivers/char/lrng/lrng_sha1.c
new file mode 100644
index 000000000..9cbc7a6fe
--- /dev/null
+++ b/drivers/char/lrng/lrng_sha1.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Backend for the LRNG providing the SHA-1 implementation that can be used
+ * without the kernel crypto API available including during early boot and in
+ * atomic contexts.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <crypto/sha1.h>
+#include <crypto/sha1_base.h>
+
+#include "lrng_sha.h"
+
+/*
+ * If the SHA-256 support is not compiled, we fall back to SHA-1 that is always
+ * compiled and present in the kernel.
+ */
+static u32 lrng_sha1_hash_digestsize(void *hash)
+{
+	return SHA1_DIGEST_SIZE;
+}
+
+static void lrng_sha1_block_fn(struct sha1_state *sctx, const u8 *src,
+			       int blocks)
+{
+	u32 temp[SHA1_WORKSPACE_WORDS];
+
+	while (blocks--) {
+		sha1_transform(sctx->state, src, temp);
+		src += SHA1_BLOCK_SIZE;
+	}
+	memzero_explicit(temp, sizeof(temp));
+}
+
+static int lrng_sha1_hash_init(struct shash_desc *shash, void *hash)
+{
+	/*
+	 * We do not need a TFM - we only need sufficient space for
+	 * struct sha1_state on the stack.
+	 */
+	sha1_base_init(shash);
+	return 0;
+}
+
+static int lrng_sha1_hash_update(struct shash_desc *shash,
+				 const u8 *inbuf, u32 inbuflen)
+{
+	return sha1_base_do_update(shash, inbuf, inbuflen, lrng_sha1_block_fn);
+}
+
+static int lrng_sha1_hash_final(struct shash_desc *shash, u8 *digest)
+{
+	return sha1_base_do_finalize(shash, lrng_sha1_block_fn) ?:
+	       sha1_base_finish(shash, digest);
+}
+
+static const char *lrng_sha1_hash_name(void)
+{
+	return "SHA-1";
+}
+
+static void lrng_sha1_hash_desc_zero(struct shash_desc *shash)
+{
+	memzero_explicit(shash_desc_ctx(shash), sizeof(struct sha1_state));
+}
+
+static void *lrng_sha1_hash_alloc(void)
+{
+	pr_info("Hash %s allocated\n", lrng_sha1_hash_name());
+	return NULL;
+}
+
+static void lrng_sha1_hash_dealloc(void *hash) { }
+
+const struct lrng_hash_cb lrng_sha_hash_cb = {
+	.hash_name		= lrng_sha1_hash_name,
+	.hash_alloc		= lrng_sha1_hash_alloc,
+	.hash_dealloc		= lrng_sha1_hash_dealloc,
+	.hash_digestsize	= lrng_sha1_hash_digestsize,
+	.hash_init		= lrng_sha1_hash_init,
+	.hash_update		= lrng_sha1_hash_update,
+	.hash_final		= lrng_sha1_hash_final,
+	.hash_desc_zero		= lrng_sha1_hash_desc_zero,
+};
diff --git a/drivers/char/lrng/lrng_sha256.c b/drivers/char/lrng/lrng_sha256.c
new file mode 100644
index 000000000..50705351a
--- /dev/null
+++ b/drivers/char/lrng/lrng_sha256.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * Backend for the LRNG providing the SHA-256 implementation that can be used
+ * without the kernel crypto API available including during early boot and in
+ * atomic contexts.
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <crypto/sha2.h>
+
+#include "lrng_sha.h"
+
+static u32 lrng_sha256_hash_digestsize(void *hash)
+{
+	return SHA256_DIGEST_SIZE;
+}
+
+static int lrng_sha256_hash_init(struct shash_desc *shash, void *hash)
+{
+	/*
+	 * We do not need a TFM - we only need sufficient space for
+	 * struct sha256_state on the stack.
+	 */
+	sha256_init(shash_desc_ctx(shash));
+	return 0;
+}
+
+static int lrng_sha256_hash_update(struct shash_desc *shash,
+				   const u8 *inbuf, u32 inbuflen)
+{
+	sha256_update(shash_desc_ctx(shash), inbuf, inbuflen);
+	return 0;
+}
+
+static int lrng_sha256_hash_final(struct shash_desc *shash, u8 *digest)
+{
+	sha256_final(shash_desc_ctx(shash), digest);
+	return 0;
+}
+
+static const char *lrng_sha256_hash_name(void)
+{
+	return "SHA-256";
+}
+
+static void lrng_sha256_hash_desc_zero(struct shash_desc *shash)
+{
+	memzero_explicit(shash_desc_ctx(shash), sizeof(struct sha256_state));
+}
+
+static void *lrng_sha256_hash_alloc(void)
+{
+	pr_info("Hash %s allocated\n", lrng_sha256_hash_name());
+	return NULL;
+}
+
+static void lrng_sha256_hash_dealloc(void *hash) { }
+
+const struct lrng_hash_cb lrng_sha_hash_cb = {
+	.hash_name		= lrng_sha256_hash_name,
+	.hash_alloc		= lrng_sha256_hash_alloc,
+	.hash_dealloc		= lrng_sha256_hash_dealloc,
+	.hash_digestsize	= lrng_sha256_hash_digestsize,
+	.hash_init		= lrng_sha256_hash_init,
+	.hash_update		= lrng_sha256_hash_update,
+	.hash_final		= lrng_sha256_hash_final,
+	.hash_desc_zero		= lrng_sha256_hash_desc_zero,
+};
diff --git a/drivers/char/lrng/lrng_switch.c b/drivers/char/lrng/lrng_switch.c
new file mode 100644
index 000000000..aae755949
--- /dev/null
+++ b/drivers/char/lrng/lrng_switch.c
@@ -0,0 +1,286 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG DRNG switching support
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+
+#include "lrng_es_aux.h"
+#include "lrng_es_mgr.h"
+#include "lrng_interface_dev_common.h"
+#include "lrng_numa.h"
+
+static int __maybe_unused
+lrng_hash_switch(struct lrng_drng *drng_store, const void *cb, int node)
+{
+	const struct lrng_hash_cb *new_cb = (const struct lrng_hash_cb *)cb;
+	const struct lrng_hash_cb *old_cb = drng_store->hash_cb;
+	unsigned long flags;
+	u32 i;
+	void *new_hash, *old_hash;
+	int ret;
+
+	if (node == -1)
+		return 0;
+
+	new_hash = new_cb->hash_alloc();
+	old_hash = drng_store->hash;
+
+	if (IS_ERR(new_hash)) {
+		pr_warn("could not allocate new LRNG pool hash (%ld)\n",
+			PTR_ERR(new_hash));
+		return PTR_ERR(new_hash);
+	}
+
+	if (new_cb->hash_digestsize(new_hash) > LRNG_MAX_DIGESTSIZE) {
+		pr_warn("digest size of newly requested hash too large\n");
+		new_cb->hash_dealloc(new_hash);
+		return -EINVAL;
+	}
+
+	write_lock_irqsave(&drng_store->hash_lock, flags);
+
+	/* Trigger the switch for each entropy source */
+	for_each_lrng_es(i) {
+		if (!lrng_es[i]->switch_hash)
+			continue;
+		ret = lrng_es[i]->switch_hash(drng_store, node, new_cb,
+					      new_hash, old_cb);
+		if (ret) {
+			u32 j;
+
+			/* Revert all already executed operations */
+			for (j = 0; j < i; j++) {
+				if (!lrng_es[j]->switch_hash)
+					continue;
+				WARN_ON(lrng_es[j]->switch_hash(drng_store,
+								node, old_cb,
+								old_hash,
+								new_cb));
+			}
+			goto err;
+		}
+	}
+
+	drng_store->hash = new_hash;
+	drng_store->hash_cb = new_cb;
+	old_cb->hash_dealloc(old_hash);
+	pr_info("Conditioning function allocated for DRNG for NUMA node %d\n",
+		node);
+
+err:
+	write_unlock_irqrestore(&drng_store->hash_lock, flags);
+	return ret;
+}
+
+static int __maybe_unused
+lrng_drng_switch(struct lrng_drng *drng_store, const void *cb, int node)
+{
+	const struct lrng_drng_cb *new_cb = (const struct lrng_drng_cb *)cb;
+	const struct lrng_drng_cb *old_cb = drng_store->drng_cb;
+	int ret;
+	u8 seed[LRNG_DRNG_SECURITY_STRENGTH_BYTES];
+	void *new_drng = new_cb->drng_alloc(LRNG_DRNG_SECURITY_STRENGTH_BYTES);
+	void *old_drng = drng_store->drng;
+	u32 current_security_strength;
+	bool reset_drng = !lrng_get_available();
+
+	if (IS_ERR(new_drng)) {
+		pr_warn("could not allocate new DRNG for NUMA node %d (%ld)\n",
+			node, PTR_ERR(new_drng));
+		return PTR_ERR(new_drng);
+	}
+
+	current_security_strength = lrng_security_strength();
+	mutex_lock(&drng_store->lock);
+
+	/*
+	 * Pull from existing DRNG to seed new DRNG regardless of seed status
+	 * of old DRNG -- the entropy state for the DRNG is left unchanged which
+	 * implies that als the new DRNG is reseeded when deemed necessary. This
+	 * seeding of the new DRNG shall only ensure that the new DRNG has the
+	 * same entropy as the old DRNG.
+	 */
+	ret = old_cb->drng_generate(old_drng, seed, sizeof(seed));
+	mutex_unlock(&drng_store->lock);
+
+	if (ret < 0) {
+		reset_drng = true;
+		pr_warn("getting random data from DRNG failed for NUMA node %d (%d)\n",
+			node, ret);
+	} else {
+		/* seed new DRNG with data */
+		ret = new_cb->drng_seed(new_drng, seed, ret);
+		memzero_explicit(seed, sizeof(seed));
+		if (ret < 0) {
+			reset_drng = true;
+			pr_warn("seeding of new DRNG failed for NUMA node %d (%d)\n",
+				node, ret);
+		} else {
+			pr_debug("seeded new DRNG of NUMA node %d instance from old DRNG instance\n",
+				 node);
+		}
+	}
+
+	mutex_lock(&drng_store->lock);
+
+	if (reset_drng)
+		lrng_drng_reset(drng_store);
+
+	drng_store->drng = new_drng;
+	drng_store->drng_cb = new_cb;
+
+	/* Reseed if previous LRNG security strength was insufficient */
+	if (current_security_strength < lrng_security_strength())
+		drng_store->force_reseed = true;
+
+	/* Force oversampling seeding as we initialize DRNG */
+	if (IS_ENABLED(CONFIG_CRYPTO_FIPS))
+		lrng_unset_fully_seeded(drng_store);
+
+	if (lrng_state_min_seeded())
+		lrng_set_entropy_thresh(lrng_get_seed_entropy_osr(
+						drng_store->fully_seeded));
+
+	old_cb->drng_dealloc(old_drng);
+
+	pr_info("DRNG of NUMA node %d switched\n", node);
+
+	mutex_unlock(&drng_store->lock);
+	return ret;
+}
+
+/*
+ * Switch the existing DRNG and hash instances with new using the new crypto
+ * callbacks. The caller must hold the lrng_crypto_cb_update lock.
+ */
+static int lrng_switch(const void *cb,
+		       int(*switcher)(struct lrng_drng *drng_store,
+				      const void *cb, int node))
+{
+	struct lrng_drng **lrng_drng = lrng_drng_instances();
+	struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+	struct lrng_drng *lrng_drng_pr = lrng_drng_pr_instance();
+	int ret = 0;
+
+	if (lrng_drng) {
+		u32 node;
+
+		for_each_online_node(node) {
+			if (lrng_drng[node])
+				ret |= switcher(lrng_drng[node], cb, node);
+		}
+	} else {
+		ret |= switcher(lrng_drng_init, cb, 0);
+	}
+
+	ret |= switcher(lrng_drng_pr, cb, -1);
+
+	return ret;
+}
+
+/*
+ * lrng_set_drng_cb - Register new cryptographic callback functions for DRNG
+ * The registering implies that all old DRNG states are replaced with new
+ * DRNG states.
+ *
+ * drng_cb: Callback functions to be registered -- if NULL, use the default
+ *	    callbacks defined at compile time.
+ *
+ * Return:
+ * * 0 on success
+ * * < 0 on error
+ */
+int lrng_set_drng_cb(const struct lrng_drng_cb *drng_cb)
+{
+	struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+	int ret;
+
+	if (!IS_ENABLED(CONFIG_LRNG_SWITCH_DRNG))
+		return -EOPNOTSUPP;
+
+	if (!drng_cb)
+		drng_cb = lrng_default_drng_cb;
+
+	mutex_lock(&lrng_crypto_cb_update);
+
+	/*
+	 * If a callback other than the default is set, allow it only to be
+	 * set back to the default callback. This ensures that multiple
+	 * different callbacks can be registered at the same time. If a
+	 * callback different from the current callback and the default
+	 * callback shall be set, the current callback must be deregistered
+	 * (e.g. the kernel module providing it must be unloaded) and the new
+	 * implementation can be registered.
+	 */
+	if ((drng_cb != lrng_default_drng_cb) &&
+	    (lrng_drng_init->drng_cb != lrng_default_drng_cb)) {
+		pr_warn("disallow setting new DRNG callbacks, unload the old callbacks first!\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = lrng_switch(drng_cb, lrng_drng_switch);
+	/* The switch may imply new entropy due to larger DRNG sec strength. */
+	if (!ret)
+		lrng_es_add_entropy();
+
+out:
+	mutex_unlock(&lrng_crypto_cb_update);
+	return ret;
+}
+EXPORT_SYMBOL(lrng_set_drng_cb);
+
+/*
+ * lrng_set_hash_cb - Register new cryptographic callback functions for hash
+ * The registering implies that all old hash states are replaced with new
+ * hash states.
+ *
+ * @hash_cb: Callback functions to be registered -- if NULL, use the default
+ *	     callbacks defined at compile time.
+ *
+ * Return:
+ * * 0 on success
+ * * < 0 on error
+ */
+int lrng_set_hash_cb(const struct lrng_hash_cb *hash_cb)
+{
+	struct lrng_drng *lrng_drng_init = lrng_drng_init_instance();
+	int ret;
+
+	if (!IS_ENABLED(CONFIG_LRNG_SWITCH_HASH))
+		return -EOPNOTSUPP;
+
+	if (!hash_cb)
+		hash_cb = lrng_default_hash_cb;
+
+	mutex_lock(&lrng_crypto_cb_update);
+
+	/* Comment from lrng_set_drng_cb applies. */
+	if ((hash_cb != lrng_default_hash_cb) &&
+	    (lrng_drng_init->hash_cb != lrng_default_hash_cb)) {
+		pr_warn("disallow setting new hash callbacks, unload the old callbacks first!\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = lrng_switch(hash_cb, lrng_hash_switch);
+	/*
+	 * The switch may imply new entropy due to larger digest size. But
+	 * it may also offer more room in the aux pool which means we ping
+	 * any waiting entropy providers.
+	 */
+	if (!ret) {
+		lrng_es_add_entropy();
+		lrng_writer_wakeup();
+	}
+
+out:
+	mutex_unlock(&lrng_crypto_cb_update);
+	return ret;
+}
+EXPORT_SYMBOL(lrng_set_hash_cb);
diff --git a/drivers/char/lrng/lrng_sysctl.c b/drivers/char/lrng/lrng_sysctl.c
new file mode 100644
index 000000000..ecdd96a84
--- /dev/null
+++ b/drivers/char/lrng/lrng_sysctl.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG sysctl interfaces
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#include <linux/lrng.h>
+#include <linux/proc_fs.h>
+#include <linux/sysctl.h>
+#include <linux/uuid.h>
+
+#include "lrng_drng_mgr.h"
+#include "lrng_es_mgr.h"
+#include "lrng_sysctl.h"
+
+/*
+ * This function is used to return both the bootid UUID, and random
+ * UUID.  The difference is in whether table->data is NULL; if it is,
+ * then a new UUID is generated and returned to the user.
+ *
+ * If the user accesses this via the proc interface, the UUID will be
+ * returned as an ASCII string in the standard UUID format; if via the
+ * sysctl system call, as 16 bytes of binary data.
+ */
+static int lrng_sysctl_do_uuid(struct ctl_table *table, int write,
+			       void *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct ctl_table fake_table;
+	unsigned char buf[64], tmp_uuid[16], *uuid;
+
+	uuid = table->data;
+	if (!uuid) {
+		uuid = tmp_uuid;
+		generate_random_uuid(uuid);
+	} else {
+		static DEFINE_SPINLOCK(bootid_spinlock);
+
+		spin_lock(&bootid_spinlock);
+		if (!uuid[8])
+			generate_random_uuid(uuid);
+		spin_unlock(&bootid_spinlock);
+	}
+
+	sprintf(buf, "%pU", uuid);
+
+	fake_table.data = buf;
+	fake_table.maxlen = sizeof(buf);
+
+	return proc_dostring(&fake_table, write, buffer, lenp, ppos);
+}
+
+static int lrng_sysctl_do_entropy(struct ctl_table *table, int write,
+				void *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct ctl_table fake_table;
+	int entropy_count = lrng_avail_entropy_aux();
+
+	fake_table.data = &entropy_count;
+	fake_table.maxlen = sizeof(entropy_count);
+
+	return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
+}
+
+static int lrng_sysctl_do_poolsize(struct ctl_table *table, int write,
+				   void *buffer, size_t *lenp, loff_t *ppos)
+{
+	struct ctl_table fake_table;
+	u32 entropy_count = lrng_es[lrng_ext_es_aux]->max_entropy();
+
+	fake_table.data = &entropy_count;
+	fake_table.maxlen = sizeof(entropy_count);
+
+	return proc_dointvec(&fake_table, write, buffer, lenp, ppos);
+}
+
+static int lrng_min_write_thresh;
+static int lrng_max_write_thresh = (LRNG_WRITE_WAKEUP_ENTROPY << 3);
+static char lrng_sysctl_bootid[16];
+static int lrng_drng_reseed_max_min;
+
+void lrng_sysctl_update_max_write_thresh(u32 new_digestsize)
+{
+	lrng_max_write_thresh = (int)new_digestsize;
+	/* Ensure that changes to the global variable are visible */
+	mb();
+}
+
+static struct ctl_table random_table[] = {
+	{
+		.procname	= "poolsize",
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.proc_handler	= lrng_sysctl_do_poolsize,
+	},
+	{
+		.procname	= "entropy_avail",
+		.maxlen		= sizeof(int),
+		.mode		= 0444,
+		.proc_handler	= lrng_sysctl_do_entropy,
+	},
+	{
+		.procname	= "write_wakeup_threshold",
+		.data		= &lrng_write_wakeup_bits,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= &lrng_min_write_thresh,
+		.extra2		= &lrng_max_write_thresh,
+	},
+	{
+		.procname	= "boot_id",
+		.data		= &lrng_sysctl_bootid,
+		.maxlen		= 16,
+		.mode		= 0444,
+		.proc_handler	= lrng_sysctl_do_uuid,
+	},
+	{
+		.procname	= "uuid",
+		.maxlen		= 16,
+		.mode		= 0444,
+		.proc_handler	= lrng_sysctl_do_uuid,
+	},
+	{
+		.procname       = "urandom_min_reseed_secs",
+		.data           = &lrng_drng_reseed_max_time,
+		.maxlen         = sizeof(int),
+		.mode           = 0644,
+		.proc_handler   = proc_dointvec,
+		.extra1		= &lrng_drng_reseed_max_min,
+	},
+	{ }
+};
+
+static int __init random_sysctls_init(void)
+{
+	register_sysctl_init("kernel/random", random_table);
+	return 0;
+}
+device_initcall(random_sysctls_init);
diff --git a/drivers/char/lrng/lrng_sysctl.h b/drivers/char/lrng/lrng_sysctl.h
new file mode 100644
index 000000000..4b487e507
--- /dev/null
+++ b/drivers/char/lrng/lrng_sysctl.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_SYSCTL_H
+#define _LRNG_SYSCTL_H
+
+#ifdef CONFIG_LRNG_SYSCTL
+void lrng_sysctl_update_max_write_thresh(u32 new_digestsize);
+#else
+static inline void lrng_sysctl_update_max_write_thresh(u32 new_digestsize) { }
+#endif
+
+#endif /* _LRNG_SYSCTL_H */
diff --git a/drivers/char/lrng/lrng_testing.c b/drivers/char/lrng/lrng_testing.c
new file mode 100644
index 000000000..101140085
--- /dev/null
+++ b/drivers/char/lrng/lrng_testing.c
@@ -0,0 +1,901 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+/*
+ * LRNG testing interfaces to obtain raw entropy
+ *
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/lrng.h>
+#include <linux/atomic.h>
+#include <linux/bug.h>
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/sched/signal.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <linux/workqueue.h>
+#include <asm/errno.h>
+
+#include "lrng_definitions.h"
+#include "lrng_drng_chacha20.h"
+#include "lrng_sha.h"
+#include "lrng_testing.h"
+
+#if defined(CONFIG_LRNG_RAW_SCHED_HIRES_ENTROPY) ||		\
+    defined(CONFIG_LRNG_RAW_SCHED_PID_ENTROPY) ||		\
+    defined(CONFIG_LRNG_RAW_SCHED_START_TIME_ENTROPY) ||	\
+    defined(CONFIG_LRNG_RAW_SCHED_NVCSW_ENTROPY) ||		\
+    defined(CONFIG_LRNG_SCHED_PERF)
+#define LRNG_TESTING_USE_BUSYLOOP
+#endif
+
+#ifdef CONFIG_LRNG_TESTING_RECORDING
+
+#define LRNG_TESTING_RINGBUFFER_SIZE	1024
+#define LRNG_TESTING_RINGBUFFER_MASK	(LRNG_TESTING_RINGBUFFER_SIZE - 1)
+
+struct lrng_testing {
+	u32 lrng_testing_rb[LRNG_TESTING_RINGBUFFER_SIZE];
+	u32 rb_reader;
+	atomic_t rb_writer;
+	atomic_t lrng_testing_enabled;
+	spinlock_t lock;
+	wait_queue_head_t read_wait;
+};
+
+/*************************** Generic Data Handling ****************************/
+
+/*
+ * boot variable:
+ * 0 ==> No boot test, gathering of runtime data allowed
+ * 1 ==> Boot test enabled and ready for collecting data, gathering runtime
+ *	 data is disabled
+ * 2 ==> Boot test completed and disabled, gathering of runtime data is
+ *	 disabled
+ */
+
+static void lrng_testing_reset(struct lrng_testing *data)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->lock, flags);
+	data->rb_reader = 0;
+	atomic_set(&data->rb_writer, 0);
+	spin_unlock_irqrestore(&data->lock, flags);
+}
+
+static void lrng_testing_init(struct lrng_testing *data, u32 boot)
+{
+	/*
+	 * The boot time testing implies we have a running test. If the
+	 * caller wants to clear it, he has to unset the boot_test flag
+	 * at runtime via sysfs to enable regular runtime testing
+	 */
+	if (boot)
+		return;
+
+	lrng_testing_reset(data);
+	atomic_set(&data->lrng_testing_enabled, 1);
+	pr_warn("Enabling data collection\n");
+}
+
+static void lrng_testing_fini(struct lrng_testing *data, u32 boot)
+{
+	/* If we have boot data, we do not reset yet to allow data to be read */
+	if (boot)
+		return;
+
+	atomic_set(&data->lrng_testing_enabled, 0);
+	lrng_testing_reset(data);
+	pr_warn("Disabling data collection\n");
+}
+
+static bool lrng_testing_store(struct lrng_testing *data, u32 value,
+			       u32 *boot)
+{
+	unsigned long flags;
+
+	if (!atomic_read(&data->lrng_testing_enabled) && (*boot != 1))
+		return false;
+
+	spin_lock_irqsave(&data->lock, flags);
+
+	/*
+	 * Disable entropy testing for boot time testing after ring buffer
+	 * is filled.
+	 */
+	if (*boot) {
+		if (((u32)atomic_read(&data->rb_writer)) >
+		    LRNG_TESTING_RINGBUFFER_SIZE) {
+			*boot = 2;
+			pr_warn_once("One time data collection test disabled\n");
+			spin_unlock_irqrestore(&data->lock, flags);
+			return false;
+		}
+
+		if (atomic_read(&data->rb_writer) == 1)
+			pr_warn("One time data collection test enabled\n");
+	}
+
+	data->lrng_testing_rb[((u32)atomic_read(&data->rb_writer)) &
+			      LRNG_TESTING_RINGBUFFER_MASK] = value;
+	atomic_inc(&data->rb_writer);
+
+	spin_unlock_irqrestore(&data->lock, flags);
+
+#ifndef LRNG_TESTING_USE_BUSYLOOP
+	if (wq_has_sleeper(&data->read_wait))
+		wake_up_interruptible(&data->read_wait);
+#endif
+
+	return true;
+}
+
+static bool lrng_testing_have_data(struct lrng_testing *data)
+{
+	return ((((u32)atomic_read(&data->rb_writer)) &
+		 LRNG_TESTING_RINGBUFFER_MASK) !=
+		 (data->rb_reader & LRNG_TESTING_RINGBUFFER_MASK));
+}
+
+static int lrng_testing_reader(struct lrng_testing *data, u32 *boot,
+			       u8 *outbuf, u32 outbuflen)
+{
+	unsigned long flags;
+	int collected_data = 0;
+
+	lrng_testing_init(data, *boot);
+
+	while (outbuflen) {
+		u32 writer = (u32)atomic_read(&data->rb_writer);
+
+		spin_lock_irqsave(&data->lock, flags);
+
+		/* We have no data or reached the writer. */
+		if (!writer || (writer == data->rb_reader)) {
+
+			spin_unlock_irqrestore(&data->lock, flags);
+
+			/*
+			 * Now we gathered all boot data, enable regular data
+			 * collection.
+			 */
+			if (*boot) {
+				*boot = 0;
+				goto out;
+			}
+
+#ifdef LRNG_TESTING_USE_BUSYLOOP
+			while (!lrng_testing_have_data(data))
+				;
+#else
+			wait_event_interruptible(data->read_wait,
+						 lrng_testing_have_data(data));
+#endif
+			if (signal_pending(current)) {
+				collected_data = -ERESTARTSYS;
+				goto out;
+			}
+
+			continue;
+		}
+
+		/* We copy out word-wise */
+		if (outbuflen < sizeof(u32)) {
+			spin_unlock_irqrestore(&data->lock, flags);
+			goto out;
+		}
+
+		memcpy(outbuf, &data->lrng_testing_rb[data->rb_reader],
+		       sizeof(u32));
+		data->rb_reader++;
+
+		spin_unlock_irqrestore(&data->lock, flags);
+
+		outbuf += sizeof(u32);
+		outbuflen -= sizeof(u32);
+		collected_data += sizeof(u32);
+	}
+
+out:
+	lrng_testing_fini(data, *boot);
+	return collected_data;
+}
+
+static int lrng_testing_extract_user(struct file *file, char __user *buf,
+				     size_t nbytes, loff_t *ppos,
+				     int (*reader)(u8 *outbuf, u32 outbuflen))
+{
+	u8 *tmp, *tmp_aligned;
+	int ret = 0, large_request = (nbytes > 256);
+
+	if (!nbytes)
+		return 0;
+
+	/*
+	 * The intention of this interface is for collecting at least
+	 * 1000 samples due to the SP800-90B requirements. So, we make no
+	 * effort in avoiding allocating more memory that actually needed
+	 * by the user. Hence, we allocate sufficient memory to always hold
+	 * that amount of data.
+	 */
+	tmp = kmalloc(LRNG_TESTING_RINGBUFFER_SIZE + sizeof(u32), GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+
+	tmp_aligned = PTR_ALIGN(tmp, sizeof(u32));
+
+	while (nbytes) {
+		int i;
+
+		if (large_request && need_resched()) {
+			if (signal_pending(current)) {
+				if (ret == 0)
+					ret = -ERESTARTSYS;
+				break;
+			}
+			schedule();
+		}
+
+		i = min_t(int, nbytes, LRNG_TESTING_RINGBUFFER_SIZE);
+		i = reader(tmp_aligned, i);
+		if (i <= 0) {
+			if (i < 0)
+				ret = i;
+			break;
+		}
+		if (copy_to_user(buf, tmp_aligned, i)) {
+			ret = -EFAULT;
+			break;
+		}
+
+		nbytes -= i;
+		buf += i;
+		ret += i;
+	}
+
+	kfree_sensitive(tmp);
+
+	if (ret > 0)
+		*ppos += ret;
+
+	return ret;
+}
+
+#endif /* CONFIG_LRNG_TESTING_RECORDING */
+
+/************* Raw High-Resolution IRQ Timer Entropy Data Handling ************/
+
+#ifdef CONFIG_LRNG_RAW_HIRES_ENTROPY
+
+static u32 boot_raw_hires_test = 0;
+module_param(boot_raw_hires_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_hires_test, "Enable gathering boot time high resolution timer entropy of the first IRQ entropy events");
+
+static struct lrng_testing lrng_raw_hires = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_hires.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_hires.read_wait)
+};
+
+bool lrng_raw_hires_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_hires, value, &boot_raw_hires_test);
+}
+
+static int lrng_raw_hires_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_hires, &boot_raw_hires_test,
+				   outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_hires_read(struct file *file, char __user *to,
+				   size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_hires_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_hires_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_hires_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_HIRES_ENTROPY */
+
+/********************* Raw Jiffies Entropy Data Handling **********************/
+
+#ifdef CONFIG_LRNG_RAW_JIFFIES_ENTROPY
+
+static u32 boot_raw_jiffies_test = 0;
+module_param(boot_raw_jiffies_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_jiffies_test, "Enable gathering boot time high resolution timer entropy of the first entropy events");
+
+static struct lrng_testing lrng_raw_jiffies = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_jiffies.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_jiffies.read_wait)
+};
+
+bool lrng_raw_jiffies_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_jiffies, value,
+				  &boot_raw_jiffies_test);
+}
+
+static int lrng_raw_jiffies_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_jiffies, &boot_raw_jiffies_test,
+				   outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_jiffies_read(struct file *file, char __user *to,
+				   size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_jiffies_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_jiffies_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_jiffies_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_JIFFIES_ENTROPY */
+
+/************************** Raw IRQ Data Handling ****************************/
+
+#ifdef CONFIG_LRNG_RAW_IRQ_ENTROPY
+
+static u32 boot_raw_irq_test = 0;
+module_param(boot_raw_irq_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_irq_test, "Enable gathering boot time entropy of the first IRQ entropy events");
+
+static struct lrng_testing lrng_raw_irq = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_irq.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_irq.read_wait)
+};
+
+bool lrng_raw_irq_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_irq, value, &boot_raw_irq_test);
+}
+
+static int lrng_raw_irq_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_irq, &boot_raw_irq_test, outbuf,
+				   outbuflen);
+}
+
+static ssize_t lrng_raw_irq_read(struct file *file, char __user *to,
+				 size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_irq_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_irq_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_irq_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_IRQ_ENTROPY */
+
+/************************ Raw _RET_IP_ Data Handling **************************/
+
+#ifdef CONFIG_LRNG_RAW_RETIP_ENTROPY
+
+static u32 boot_raw_retip_test = 0;
+module_param(boot_raw_retip_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_retip_test, "Enable gathering boot time entropy of the first return instruction pointer entropy events");
+
+static struct lrng_testing lrng_raw_retip = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_retip.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_retip.read_wait)
+};
+
+bool lrng_raw_retip_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_retip, value, &boot_raw_retip_test);
+}
+
+static int lrng_raw_retip_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_retip, &boot_raw_retip_test,
+				   outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_retip_read(struct file *file, char __user *to,
+				   size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_retip_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_retip_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_retip_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_RETIP_ENTROPY */
+
+/********************** Raw IRQ register Data Handling ************************/
+
+#ifdef CONFIG_LRNG_RAW_REGS_ENTROPY
+
+static u32 boot_raw_regs_test = 0;
+module_param(boot_raw_regs_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_regs_test, "Enable gathering boot time entropy of the first interrupt register entropy events");
+
+static struct lrng_testing lrng_raw_regs = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_regs.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_regs.read_wait)
+};
+
+bool lrng_raw_regs_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_regs, value, &boot_raw_regs_test);
+}
+
+static int lrng_raw_regs_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_regs, &boot_raw_regs_test,
+				   outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_regs_read(struct file *file, char __user *to,
+				  size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_regs_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_regs_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_regs_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_REGS_ENTROPY */
+
+/********************** Raw Entropy Array Data Handling ***********************/
+
+#ifdef CONFIG_LRNG_RAW_ARRAY
+
+static u32 boot_raw_array = 0;
+module_param(boot_raw_array, uint, 0644);
+MODULE_PARM_DESC(boot_raw_array, "Enable gathering boot time raw noise array data of the first entropy events");
+
+static struct lrng_testing lrng_raw_array = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_array.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_array.read_wait)
+};
+
+bool lrng_raw_array_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_array, value, &boot_raw_array);
+}
+
+static int lrng_raw_array_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_array, &boot_raw_array, outbuf,
+				   outbuflen);
+}
+
+static ssize_t lrng_raw_array_read(struct file *file, char __user *to,
+				   size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_array_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_array_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_array_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_ARRAY */
+
+/******************** Interrupt Performance Data Handling *********************/
+
+#ifdef CONFIG_LRNG_IRQ_PERF
+
+static u32 boot_irq_perf = 0;
+module_param(boot_irq_perf, uint, 0644);
+MODULE_PARM_DESC(boot_irq_perf, "Enable gathering interrupt entropy source performance data");
+
+static struct lrng_testing lrng_irq_perf = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_irq_perf.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_irq_perf.read_wait)
+};
+
+bool lrng_perf_time(u32 start)
+{
+	return lrng_testing_store(&lrng_irq_perf, random_get_entropy() - start,
+				  &boot_irq_perf);
+}
+
+static int lrng_irq_perf_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_irq_perf, &boot_irq_perf, outbuf,
+				   outbuflen);
+}
+
+static ssize_t lrng_irq_perf_read(struct file *file, char __user *to,
+				  size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_irq_perf_reader);
+}
+
+static const struct file_operations lrng_irq_perf_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_irq_perf_read,
+};
+
+#endif /* CONFIG_LRNG_IRQ_PERF */
+
+/****** Raw High-Resolution Scheduler-based Timer Entropy Data Handling *******/
+
+#ifdef CONFIG_LRNG_RAW_SCHED_HIRES_ENTROPY
+
+static u32 boot_raw_sched_hires_test = 0;
+module_param(boot_raw_sched_hires_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_sched_hires_test, "Enable gathering boot time high resolution timer entropy of the first Scheduler-based entropy events");
+
+static struct lrng_testing lrng_raw_sched_hires = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_sched_hires.lock),
+	.read_wait =
+		__WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_sched_hires.read_wait)
+};
+
+bool lrng_raw_sched_hires_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_sched_hires, value,
+				  &boot_raw_sched_hires_test);
+}
+
+static int lrng_raw_sched_hires_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_sched_hires,
+				   &boot_raw_sched_hires_test,
+				   outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_sched_hires_read(struct file *file, char __user *to,
+					 size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_sched_hires_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_sched_hires_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_sched_hires_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_SCHED_HIRES_ENTROPY */
+
+/******************** Interrupt Performance Data Handling *********************/
+
+#ifdef CONFIG_LRNG_SCHED_PERF
+
+static u32 boot_sched_perf = 0;
+module_param(boot_sched_perf, uint, 0644);
+MODULE_PARM_DESC(boot_sched_perf, "Enable gathering scheduler-based entropy source performance data");
+
+static struct lrng_testing lrng_sched_perf = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_sched_perf.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_sched_perf.read_wait)
+};
+
+bool lrng_sched_perf_time(u32 start)
+{
+	return lrng_testing_store(&lrng_sched_perf, random_get_entropy() - start,
+				  &boot_sched_perf);
+}
+
+static int lrng_sched_perf_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_sched_perf, &boot_sched_perf, outbuf,
+				   outbuflen);
+}
+
+static ssize_t lrng_sched_perf_read(struct file *file, char __user *to,
+				    size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_sched_perf_reader);
+}
+
+static const struct file_operations lrng_sched_perf_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_sched_perf_read,
+};
+
+#endif /* CONFIG_LRNG_SCHED_PERF */
+
+/*************** Raw Scheduler task_struct->pid Data Handling *****************/
+
+#ifdef CONFIG_LRNG_RAW_SCHED_PID_ENTROPY
+
+static u32 boot_raw_sched_pid_test = 0;
+module_param(boot_raw_sched_pid_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_sched_pid_test, "Enable gathering boot time entropy of the first PIDs collected by the scheduler entropy source");
+
+static struct lrng_testing lrng_raw_sched_pid = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_sched_pid.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_sched_pid.read_wait)
+};
+
+bool lrng_raw_sched_pid_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_sched_pid, value,
+				  &boot_raw_sched_pid_test);
+}
+
+static int lrng_raw_sched_pid_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_sched_pid,
+				   &boot_raw_sched_pid_test, outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_sched_pid_read(struct file *file, char __user *to,
+				       size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_sched_pid_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_sched_pid_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_sched_pid_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_SCHED_PID_ENTROPY */
+
+
+/*********** Raw Scheduler task_struct->start_time Data Handling **************/
+
+#ifdef CONFIG_LRNG_RAW_SCHED_START_TIME_ENTROPY
+
+static u32 boot_raw_sched_starttime_test = 0;
+module_param(boot_raw_sched_starttime_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_sched_starttime_test, "Enable gathering boot time entropy of the first task start times collected by the scheduler entropy source");
+
+static struct lrng_testing lrng_raw_sched_starttime = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_sched_starttime.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_sched_starttime.read_wait)
+};
+
+bool lrng_raw_sched_starttime_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_sched_starttime, value,
+				  &boot_raw_sched_starttime_test);
+}
+
+static int lrng_raw_sched_starttime_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_sched_starttime,
+				   &boot_raw_sched_starttime_test, outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_sched_starttime_read(struct file *file, char __user *to,
+				       size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_sched_starttime_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_sched_starttime_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_sched_starttime_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_SCHED_START_TIME_ENTROPY */
+
+/************** Raw Scheduler task_struct->nvcsw Data Handling ****************/
+
+#ifdef CONFIG_LRNG_RAW_SCHED_NVCSW_ENTROPY
+
+static u32 boot_raw_sched_nvcsw_test = 0;
+module_param(boot_raw_sched_nvcsw_test, uint, 0644);
+MODULE_PARM_DESC(boot_raw_sched_nvcsw_test, "Enable gathering boot time entropy of the first task context switch numbers collected by the scheduler entropy source");
+
+static struct lrng_testing lrng_raw_sched_nvcsw = {
+	.rb_reader = 0,
+	.rb_writer = ATOMIC_INIT(0),
+	.lock      = __SPIN_LOCK_UNLOCKED(lrng_raw_sched_nvcsw.lock),
+	.read_wait = __WAIT_QUEUE_HEAD_INITIALIZER(lrng_raw_sched_nvcsw.read_wait)
+};
+
+bool lrng_raw_sched_nvcsw_entropy_store(u32 value)
+{
+	return lrng_testing_store(&lrng_raw_sched_nvcsw, value,
+				  &boot_raw_sched_nvcsw_test);
+}
+
+static int lrng_raw_sched_nvcsw_entropy_reader(u8 *outbuf, u32 outbuflen)
+{
+	return lrng_testing_reader(&lrng_raw_sched_nvcsw,
+				   &boot_raw_sched_nvcsw_test, outbuf, outbuflen);
+}
+
+static ssize_t lrng_raw_sched_nvcsw_read(struct file *file, char __user *to,
+				       size_t count, loff_t *ppos)
+{
+	return lrng_testing_extract_user(file, to, count, ppos,
+					 lrng_raw_sched_nvcsw_entropy_reader);
+}
+
+static const struct file_operations lrng_raw_sched_nvcsw_fops = {
+	.owner = THIS_MODULE,
+	.read = lrng_raw_sched_nvcsw_read,
+};
+
+#endif /* CONFIG_LRNG_RAW_SCHED_NVCSW_ENTROPY */
+
+/*********************************** ACVT ************************************/
+
+#ifdef CONFIG_LRNG_ACVT_HASH
+
+/* maximum amount of data to be hashed as defined by ACVP */
+#define LRNG_ACVT_MAX_SHA_MSG	(65536 >> 3)
+
+/*
+ * As we use static variables to store the data, it is clear that the
+ * test interface is only able to handle single threaded testing. This is
+ * considered to be sufficient for testing. If multi-threaded use of the
+ * ACVT test interface would be performed, the caller would get garbage
+ * but the kernel operation is unaffected by this.
+ */
+static u8 lrng_acvt_hash_data[LRNG_ACVT_MAX_SHA_MSG]
+						__aligned(LRNG_KCAPI_ALIGN);
+static atomic_t lrng_acvt_hash_data_size = ATOMIC_INIT(0);
+static u8 lrng_acvt_hash_digest[LRNG_ATOMIC_DIGEST_SIZE];
+
+static ssize_t lrng_acvt_hash_write(struct file *file, const char __user *buf,
+				    size_t nbytes, loff_t *ppos)
+{
+	if (nbytes > LRNG_ACVT_MAX_SHA_MSG)
+		return -EINVAL;
+
+	atomic_set(&lrng_acvt_hash_data_size, (int)nbytes);
+
+	return simple_write_to_buffer(lrng_acvt_hash_data,
+				      LRNG_ACVT_MAX_SHA_MSG, ppos, buf, nbytes);
+}
+
+static ssize_t lrng_acvt_hash_read(struct file *file, char __user *to,
+				   size_t count, loff_t *ppos)
+{
+	SHASH_DESC_ON_STACK(shash, NULL);
+	const struct lrng_hash_cb *hash_cb = &lrng_sha_hash_cb;
+	ssize_t ret;
+
+	if (count > LRNG_ATOMIC_DIGEST_SIZE)
+		return -EINVAL;
+
+	ret = hash_cb->hash_init(shash, NULL) ?:
+	      hash_cb->hash_update(shash, lrng_acvt_hash_data,
+				atomic_read_u32(&lrng_acvt_hash_data_size)) ?:
+	      hash_cb->hash_final(shash, lrng_acvt_hash_digest);
+	if (ret)
+		return ret;
+
+	return simple_read_from_buffer(to, count, ppos, lrng_acvt_hash_digest,
+				       sizeof(lrng_acvt_hash_digest));
+}
+
+static const struct file_operations lrng_acvt_hash_fops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.llseek = default_llseek,
+	.read = lrng_acvt_hash_read,
+	.write = lrng_acvt_hash_write,
+};
+
+#endif /* CONFIG_LRNG_ACVT_DRNG */
+
+/**************************************************************************
+ * Debugfs interface
+ **************************************************************************/
+
+static int __init lrng_raw_init(void)
+{
+	struct dentry *lrng_raw_debugfs_root;
+
+	lrng_raw_debugfs_root = debugfs_create_dir(KBUILD_MODNAME, NULL);
+
+#ifdef CONFIG_LRNG_RAW_HIRES_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_hires", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_hires_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_JIFFIES_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_jiffies", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_jiffies_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_IRQ_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_irq", 0400, lrng_raw_debugfs_root,
+				   NULL, &lrng_raw_irq_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_RETIP_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_retip", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_retip_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_REGS_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_regs", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_regs_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_ARRAY
+	debugfs_create_file_unsafe("lrng_raw_array", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_array_fops);
+#endif
+#ifdef CONFIG_LRNG_IRQ_PERF
+	debugfs_create_file_unsafe("lrng_irq_perf", 0400, lrng_raw_debugfs_root,
+				   NULL, &lrng_irq_perf_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_SCHED_HIRES_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_sched_hires", 0400,
+				   lrng_raw_debugfs_root,
+				   NULL, &lrng_raw_sched_hires_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_SCHED_PID_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_sched_pid", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_sched_pid_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_SCHED_START_TIME_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_sched_starttime", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_sched_starttime_fops);
+#endif
+#ifdef CONFIG_LRNG_RAW_SCHED_NVCSW_ENTROPY
+	debugfs_create_file_unsafe("lrng_raw_sched_nvcsw", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_raw_sched_nvcsw_fops);
+#endif
+#ifdef CONFIG_LRNG_SCHED_PERF
+	debugfs_create_file_unsafe("lrng_sched_perf", 0400,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_sched_perf_fops);
+#endif
+#ifdef CONFIG_LRNG_ACVT_HASH
+	debugfs_create_file_unsafe("lrng_acvt_hash", 0600,
+				   lrng_raw_debugfs_root, NULL,
+				   &lrng_acvt_hash_fops);
+#endif
+
+	return 0;
+}
+
+module_init(lrng_raw_init);
diff --git a/drivers/char/lrng/lrng_testing.h b/drivers/char/lrng/lrng_testing.h
new file mode 100644
index 000000000..672a7fca4
--- /dev/null
+++ b/drivers/char/lrng/lrng_testing.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_TESTING_H
+#define _LRNG_TESTING_H
+
+#ifdef CONFIG_LRNG_RAW_HIRES_ENTROPY
+bool lrng_raw_hires_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_HIRES_ENTROPY */
+static inline bool lrng_raw_hires_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_HIRES_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_JIFFIES_ENTROPY
+bool lrng_raw_jiffies_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_JIFFIES_ENTROPY */
+static inline bool lrng_raw_jiffies_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_JIFFIES_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_IRQ_ENTROPY
+bool lrng_raw_irq_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_IRQ_ENTROPY */
+static inline bool lrng_raw_irq_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_IRQ_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_RETIP_ENTROPY
+bool lrng_raw_retip_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_RETIP_ENTROPY */
+static inline bool lrng_raw_retip_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_RETIP_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_REGS_ENTROPY
+bool lrng_raw_regs_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_REGS_ENTROPY */
+static inline bool lrng_raw_regs_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_REGS_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_ARRAY
+bool lrng_raw_array_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_ARRAY */
+static inline bool lrng_raw_array_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_ARRAY */
+
+#ifdef CONFIG_LRNG_IRQ_PERF
+bool lrng_perf_time(u32 start);
+#else /* CONFIG_LRNG_IRQ_PERF */
+static inline bool lrng_perf_time(u32 start) { return false; }
+#endif /*CONFIG_LRNG_IRQ_PERF */
+
+#ifdef CONFIG_LRNG_RAW_SCHED_HIRES_ENTROPY
+bool lrng_raw_sched_hires_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_SCHED_HIRES_ENTROPY */
+static inline bool
+lrng_raw_sched_hires_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_SCHED_HIRES_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_SCHED_PID_ENTROPY
+bool lrng_raw_sched_pid_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_SCHED_PID_ENTROPY */
+static inline bool
+lrng_raw_sched_pid_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_SCHED_PID_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_SCHED_START_TIME_ENTROPY
+bool lrng_raw_sched_starttime_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_SCHED_START_TIME_ENTROPY */
+static inline bool
+lrng_raw_sched_starttime_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_SCHED_START_TIME_ENTROPY */
+
+#ifdef CONFIG_LRNG_RAW_SCHED_NVCSW_ENTROPY
+bool lrng_raw_sched_nvcsw_entropy_store(u32 value);
+#else	/* CONFIG_LRNG_RAW_SCHED_NVCSW_ENTROPY */
+static inline bool
+lrng_raw_sched_nvcsw_entropy_store(u32 value) { return false; }
+#endif	/* CONFIG_LRNG_RAW_SCHED_NVCSW_ENTROPY */
+
+#ifdef CONFIG_LRNG_SCHED_PERF
+bool lrng_sched_perf_time(u32 start);
+#else /* CONFIG_LRNG_SCHED_PERF */
+static inline bool lrng_sched_perf_time(u32 start) { return false; }
+#endif /*CONFIG_LRNG_SCHED_PERF */
+
+#endif /* _LRNG_TESTING_H */
diff --git a/include/crypto/drbg.h b/include/crypto/drbg.h
index af5ad51d3..b12ae9bde 100644
--- a/include/crypto/drbg.h
+++ b/include/crypto/drbg.h
@@ -283,4 +283,11 @@ enum drbg_prefixes {
 	DRBG_PREFIX3
 };
 
+extern int drbg_alloc_state(struct drbg_state *drbg);
+extern void drbg_dealloc_state(struct drbg_state *drbg);
+extern void drbg_convert_tfm_core(const char *cra_driver_name, int *coreref,
+				  bool *pr);
+extern const struct drbg_core drbg_cores[];
+extern unsigned short drbg_sec_strength(drbg_flag_t flags);
+
 #endif /* _DRBG_H */
diff --git a/include/linux/lrng.h b/include/linux/lrng.h
new file mode 100644
index 000000000..c0d31a03d
--- /dev/null
+++ b/include/linux/lrng.h
@@ -0,0 +1,251 @@
+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/*
+ * Copyright (C) 2022, Stephan Mueller <smueller@chronox.de>
+ */
+
+#ifndef _LRNG_H
+#define _LRNG_H
+
+#include <crypto/hash.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+
+/*
+ * struct lrng_drng_cb - cryptographic callback functions defining a DRNG
+ * @drng_name		Name of DRNG
+ * @drng_alloc:		Allocate DRNG -- the provided integer should be used for
+ *			sanity checks.
+ *			return: allocated data structure or PTR_ERR on error
+ * @drng_dealloc:	Deallocate DRNG
+ * @drng_seed:		Seed the DRNG with data of arbitrary length drng: is
+ *			pointer to data structure allocated with drng_alloc
+ *			return: >= 0 on success, < 0 on error
+ * @drng_generate:	Generate random numbers from the DRNG with arbitrary
+ *			length
+ */
+struct lrng_drng_cb {
+	const char *(*drng_name)(void);
+	void *(*drng_alloc)(u32 sec_strength);
+	void (*drng_dealloc)(void *drng);
+	int (*drng_seed)(void *drng, const u8 *inbuf, u32 inbuflen);
+	int (*drng_generate)(void *drng, u8 *outbuf, u32 outbuflen);
+};
+
+/*
+ * struct lrng_hash_cb - cryptographic callback functions defining a hash
+ * @hash_name		Name of Hash used for reading entropy pool arbitrary
+ *			length
+ * @hash_alloc:		Allocate the hash for reading the entropy pool
+ *			return: allocated data structure (NULL is success too)
+ *				or ERR_PTR on error
+ * @hash_dealloc:	Deallocate Hash
+ * @hash_digestsize:	Return the digestsize for the used hash to read out
+ *			entropy pool
+ *			hash: is pointer to data structure allocated with
+ *			      hash_alloc
+ *			return: size of digest of hash in bytes
+ * @hash_init:		Initialize hash
+ *			hash: is pointer to data structure allocated with
+ *			      hash_alloc
+ *			return: 0 on success, < 0 on error
+ * @hash_update:	Update hash operation
+ *			hash: is pointer to data structure allocated with
+ *			      hash_alloc
+ *			return: 0 on success, < 0 on error
+ * @hash_final		Final hash operation
+ *			hash: is pointer to data structure allocated with
+ *			      hash_alloc
+ *			return: 0 on success, < 0 on error
+ * @hash_desc_zero	Zeroization of hash state buffer
+ *
+ * Assumptions:
+ *
+ * 1. Hash operation will not sleep
+ * 2. The hash' volatile state information is provided with *shash by caller.
+ */
+struct lrng_hash_cb {
+	const char *(*hash_name)(void);
+	void *(*hash_alloc)(void);
+	void (*hash_dealloc)(void *hash);
+	u32 (*hash_digestsize)(void *hash);
+	int (*hash_init)(struct shash_desc *shash, void *hash);
+	int (*hash_update)(struct shash_desc *shash, const u8 *inbuf,
+			   u32 inbuflen);
+	int (*hash_final)(struct shash_desc *shash, u8 *digest);
+	void (*hash_desc_zero)(struct shash_desc *shash);
+};
+
+/* Register cryptographic backend */
+#ifdef CONFIG_LRNG_SWITCH
+int lrng_set_drng_cb(const struct lrng_drng_cb *cb);
+int lrng_set_hash_cb(const struct lrng_hash_cb *cb);
+#else	/* CONFIG_LRNG_SWITCH */
+static inline int
+lrng_set_drng_cb(const struct lrng_drng_cb *cb) { return -EOPNOTSUPP; }
+static inline int
+lrng_set_hash_cb(const struct lrng_hash_cb *cb) { return -EOPNOTSUPP; }
+#endif	/* CONFIG_LRNG_SWITCH */
+
+/* Callback to feed events to the scheduler entropy source */
+#ifdef CONFIG_LRNG_SCHED
+extern void add_sched_randomness(const struct task_struct *p, int cpu);
+#else
+static inline void
+add_sched_randomness(const struct task_struct *p, int cpu) { }
+#endif
+
+/*
+ * lrng_get_random_bytes() - Provider of cryptographic strong random numbers
+ * for kernel-internal usage.
+ *
+ * This function is appropriate for in-kernel use cases operating in atomic
+ * contexts. It will always use the ChaCha20 DRNG and it may be the case that
+ * it is not fully seeded when being used.
+ *
+ * @buf: buffer to store the random bytes
+ * @nbytes: size of the buffer
+ */
+#ifdef CONFIG_LRNG_DRNG_ATOMIC
+void lrng_get_random_bytes(void *buf, int nbytes);
+#endif
+
+/*
+ * lrng_get_random_bytes_full() - Provider of cryptographic strong
+ * random numbers for kernel-internal usage from a fully initialized LRNG.
+ *
+ * This function will always return random numbers from a fully seeded and
+ * fully initialized LRNG.
+ *
+ * This function is appropriate only for non-atomic use cases as this
+ * function may sleep. It provides access to the full functionality of LRNG
+ * including the switchable DRNG support, that may support other DRNGs such
+ * as the SP800-90A DRBG.
+ *
+ * @buf: buffer to store the random bytes
+ * @nbytes: size of the buffer
+ */
+#ifdef CONFIG_LRNG
+void lrng_get_random_bytes_full(void *buf, int nbytes);
+#endif
+
+/*
+ * lrng_get_random_bytes_min() - Provider of cryptographic strong
+ * random numbers for kernel-internal usage from at least a minimally seeded
+ * LRNG, which is not necessarily fully initialized yet (e.g. SP800-90C
+ * oversampling applied in FIPS mode is not applied yet).
+ *
+ * This function is appropriate only for non-atomic use cases as this
+ * function may sleep. It provides access to the full functionality of LRNG
+ * including the switchable DRNG support, that may support other DRNGs such
+ * as the SP800-90A DRBG.
+ *
+ * @buf: buffer to store the random bytes
+ * @nbytes: size of the buffer
+ */
+#ifdef CONFIG_LRNG
+void lrng_get_random_bytes_min(void *buf, int nbytes);
+#endif
+
+/*
+ * lrng_get_random_bytes_pr() - Provider of cryptographic strong
+ * random numbers for kernel-internal usage from a fully initialized LRNG and
+ * requiring a reseed from the entropy sources before.
+ *
+ * This function will always return random numbers from a fully seeded and
+ * fully initialized LRNG.
+ *
+ * This function is appropriate only for non-atomic use cases as this
+ * function may sleep. It provides access to the full functionality of LRNG
+ * including the switchable DRNG support, that may support other DRNGs such
+ * as the SP800-90A DRBG.
+ *
+ * This call only returns no more data than entropy was pulled from the
+ * entropy sources. Thus, it is likely that this call returns less data
+ * than requested by the caller. Also, the caller MUST be prepared that this
+ * call returns 0 bytes, i.e. it did not generate data.
+ *
+ * @buf: buffer to store the random bytes
+ * @nbytes: size of the buffer
+ *
+ * @return: positive number indicates amount of generated bytes, < 0 on error
+ */
+#ifdef CONFIG_LRNG
+int lrng_get_random_bytes_pr(void *buf, int nbytes);
+#endif
+
+/*
+ * lrng_get_seed() - Fill buffer with data from entropy sources
+ *
+ * This call allows accessing the entropy sources directly and fill the buffer
+ * with data from all available entropy sources. This filled buffer is
+ * identical to the temporary seed buffer used by the LRNG to seed its DRNGs.
+ *
+ * The call is to allows users to seed their DRNG directly from the entropy
+ * sources in case the caller does not want to use the LRNG's DRNGs. This
+ * buffer can be directly used to seed the caller's DRNG from.
+ *
+ * The call blocks as long as one LRNG DRNG is not yet fully seeded. If
+ * LRNG_GET_SEED_NONBLOCK is specified, it does not block in this case, but
+ * returns with an error.
+ *
+ * Considering SP800-90C, there is a differentiation between the seeding
+ * requirements during instantiating a DRNG and at runtime of the DRNG. When
+ * specifying LRNG_GET_SEED_FULLY_SEEDED the caller indicates the DRNG was
+ * already fully seeded and the regular amount of entropy is requested.
+ * Otherwise, the LRNG will obtain the entropy rate required for initial
+ * seeding. The following minimum entropy rates will be obtained:
+ *
+ * * FIPS mode:
+ *	* Initial seeding: 384 bits of entropy
+ *	* Runtime seeding: 256 bits of entropy
+ * * Non-FIPS mode:
+ *	* 128 bits of entropy in any case
+ *
+ * Albeit these are minimum entropy rates, the LRNG tries to request the
+ * given amount of entropy from each entropy source individually. If the
+ * minimum amount of entropy cannot be obtained collectively by all entropy
+ * sources, the LRNG will not fill the buffer.
+ *
+ * The return data in buf is structurally equivalent to the following
+ * definition:
+ *
+ * struct {
+ *	u64 seedlen;
+ *	u64 entropy_rate;
+ *	struct entropy_buf seed;
+ * } __attribute((__packed__));
+ *
+ * As struct entropy_buf is not known outsize of the LRNG, the LRNG fills
+ * seedlen first with the size of struct entropy_buf. If the caller-provided
+ * buffer buf is smaller than u64, then -EINVAL is returned
+ * and buf is not touched. If it is u64 or larger but smaller
+ * than the size of the structure above, -EMSGSIZE is returned and seedlen
+ * is filled with the size of the buffer. Finally, if buf is large
+ * enough to hold all data, it is filled with the seed data and the seedlen
+ * is set to sizeof(struct entropy_buf). The entropy rate is returned with
+ * the variable entropy_rate and provides the value in bits.
+ *
+ * The seed buffer is the data that should be handed to the caller's DRNG as
+ * seed data.
+ *
+ * @buf [out] Buffer to be filled with data from the entropy sources - note, the
+ *	      buffer is marked as u64 to ensure it is aligned to 64 bits.
+ * @nbytes [in] Size of the buffer allocated by the caller - this value
+ *		provides size of @param buf in bytes.
+ * @flags [in] Flags field to adjust the behavior
+ *
+ * @return -EINVAL or -EMSGSIZE indicating the buffer is too small, -EAGAIN when
+ *	   the call would block, but NONBLOCK is specified, > 0 the size of
+ *	   the filled buffer.
+ */
+#ifdef CONFIG_LRNG
+enum lrng_get_seed_flags {
+	LRNG_GET_SEED_NONBLOCK = 0x0001, /**< Do not block the call */
+	LRNG_GET_SEED_FULLY_SEEDED = 0x0002, /**< DRNG is fully seeded */
+};
+
+ssize_t lrng_get_seed(u64 *buf, size_t nbytes, unsigned int flags);
+#endif
+
+#endif /* _LRNG_H */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 0d18c3969..e79d166f8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6,6 +6,7 @@
  *
  *  Copyright (C) 1991-2002  Linus Torvalds
  */
+#include <linux/lrng.h>
 #include <linux/highmem.h>
 #include <linux/hrtimer_api.h>
 #include <linux/ktime_api.h>
@@ -3645,6 +3646,8 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
 {
 	struct rq *rq;
 
+	add_sched_randomness(p, cpu);
+
 	if (!schedstat_enabled())
 		return;
 
-- 
2.40.0.71.g950264636c

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