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openSUSE:Leap:15.4:Update
xen.17648
5d4d850a-introduce-bss-percpu-page-aligned.patch
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File 5d4d850a-introduce-bss-percpu-page-aligned.patch of Package xen.17648
# Commit 6c9639a72f0ca3a9430ef75f375877182281fdef # Date 2019-08-09 16:36:58 +0200 # Author Andrew Cooper <andrew.cooper3@citrix.com> # Committer Jan Beulich <jbeulich@suse.com> xen/link: Introduce .bss.percpu.page_aligned Future changes are going to need to page align some percpu data. Shuffle the exact link order of items within the BSS to give .bss.percpu.page_aligned appropriate alignment, even on CPU0, which uses .bss.percpu itself. Insert explicit alignment such that there won't be a gap between __per_cpu_start and the first actual per-CPU object. The POINTER_ALIGN for __bss_end is to cover the lack of SMP_CACHE_BYTES alignment, as the loops which zero the BSS use pointer-sized stores on all architectures. Rework __DEFINE_PER_CPU() so the caller passes in all attributes, and adjust DEFINE_PER_CPU{,_READ_MOSTLY}() to match. This has the added bonus that it is now possible to grep for .bss.percpu and find all the users. Finally, introduce DEFINE_PER_CPU_PAGE_ALIGNED() which specifies the section attribute and verifies the type's alignment. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Make DEFINE_PER_CPU_PAGE_ALIGNED() verify the alignment rather than specifying it. It is the underlying type which should be suitably aligned. Signed-off-by: Jan Beulich <jbeulich@suse.com> Acked-by: Julien Grall <julien.grall@arm.com> Acked-by: Andrew Cooper <andrew.cooper3@citrix.com> --- a/xen/arch/arm/xen.lds.S +++ b/xen/arch/arm/xen.lds.S @@ -183,14 +183,16 @@ SECTIONS *(.bss.stack_aligned) . = ALIGN(PAGE_SIZE); *(.bss.page_aligned) - *(.bss) - . = ALIGN(SMP_CACHE_BYTES); + . = ALIGN(PAGE_SIZE); __per_cpu_start = .; + *(.bss.percpu.page_aligned) *(.bss.percpu) . = ALIGN(SMP_CACHE_BYTES); *(.bss.percpu.read_mostly) . = ALIGN(SMP_CACHE_BYTES); __per_cpu_data_end = .; + *(.bss) + . = ALIGN(POINTER_ALIGN); __bss_end = .; } :text _end = . ; --- a/xen/arch/x86/xen.lds.S +++ b/xen/arch/x86/xen.lds.S @@ -254,14 +254,16 @@ SECTIONS __bss_start = .; *(.bss.stack_aligned) *(.bss.page_aligned*) - *(.bss) - . = ALIGN(SMP_CACHE_BYTES); + . = ALIGN(PAGE_SIZE); __per_cpu_start = .; + *(.bss.percpu.page_aligned) *(.bss.percpu) . = ALIGN(SMP_CACHE_BYTES); *(.bss.percpu.read_mostly) . = ALIGN(SMP_CACHE_BYTES); __per_cpu_data_end = .; + *(.bss) + . = ALIGN(POINTER_ALIGN); __bss_end = .; } :text _end = . ; --- a/xen/include/asm-arm/percpu.h +++ b/xen/include/asm-arm/percpu.h @@ -16,10 +16,8 @@ extern char __per_cpu_start[], __per_cpu extern unsigned long __per_cpu_offset[NR_CPUS]; void percpu_init_areas(void); -/* Separate out the type, so (int[3], foo) works. */ -#define __DEFINE_PER_CPU(type, name, suffix) \ - __section(".bss.percpu" #suffix) \ - __typeof__(type) per_cpu_##name +#define __DEFINE_PER_CPU(attr, type, name) \ + attr __typeof__(type) per_cpu_ ## name #define per_cpu(var, cpu) \ (*RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu])) --- a/xen/include/asm-x86/percpu.h +++ b/xen/include/asm-x86/percpu.h @@ -7,10 +7,8 @@ extern unsigned long __per_cpu_offset[NR void percpu_init_areas(void); #endif -/* Separate out the type, so (int[3], foo) works. */ -#define __DEFINE_PER_CPU(type, name, suffix) \ - __section(".bss.percpu" #suffix) \ - __typeof__(type) per_cpu_##name +#define __DEFINE_PER_CPU(attr, type, name) \ + attr __typeof__(type) per_cpu_ ## name /* var is in discarded region: offset to particular copy we want */ #define per_cpu(var, cpu) \ --- a/xen/include/xen/percpu.h +++ b/xen/include/xen/percpu.h @@ -9,9 +9,17 @@ * The _##name concatenation is being used here to prevent 'name' from getting * macro expanded, while still allowing a per-architecture symbol name prefix. */ -#define DEFINE_PER_CPU(type, name) __DEFINE_PER_CPU(type, _##name, ) +#define DEFINE_PER_CPU(type, name) \ + __DEFINE_PER_CPU(__section(".bss.percpu"), type, _ ## name) + +#define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \ + typedef char name ## _chk_t \ + [BUILD_BUG_ON_ZERO(__alignof(type) & (PAGE_SIZE - 1))]; \ + __DEFINE_PER_CPU(__section(".bss.percpu.page_aligned"), \ + type, _ ## name) + #define DEFINE_PER_CPU_READ_MOSTLY(type, name) \ - __DEFINE_PER_CPU(type, _##name, .read_mostly) + __DEFINE_PER_CPU(__section(".bss.percpu.read_mostly"), type, _ ## name) /* Preferred on Xen. Also see arch-defined per_cpu(). */ #define this_cpu(var) __get_cpu_var(var)
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