File 59a0130c-x86-efi-dont-write-relocs-in-efi_arch_... of Package xen

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File 59a0130c-x86-efi-dont-write-relocs-in-efi_arch_relocate_image-1st-pass.patch of Package xen (Revision 45e6793ee80829b175f0c2513713d660)

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# Commit 34828425d36b560adfe96430b9b83dfb0f66f2a8
# Date 2017-08-25 14:07:40 +0200
# Author David Woodhouse <dwmw@amazon.co.uk>
# Committer Jan Beulich <jbeulich@suse.com>
x86/efi: don't write relocations in efi_arch_relocate_image() first pass

The function is invoked with delta=0 before ExitBootServices() is called,
as a dummy run purely to validate that all the relocations can be handled.
This allows us to exit gracefully with an error message.

However, we have relocations in read-only sections such as .rodata and
.init.te(xt). Recent versions of UEFI will actually make those sections
read-only, which will cause a fault. This functionaity was added in
EDK2 commit d0e92aad4 ("MdeModulePkg/DxeCore: Add UEFI image protection.")

It's OK to actually make the changes in the later pass because UEFI will
tear down the protection when ExitBootServices() is called, because it
knows we're going to need to do this kind of thing.

Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

--- a/xen/arch/x86/efi/efi-boot.h
+++ b/xen/arch/x86/efi/efi-boot.h
@@ -87,7 +87,8 @@ static void __init efi_arch_relocate_ima
             case PE_BASE_RELOC_DIR64:
                 if ( in_page_tables(addr) )
                     blexit(L"Unexpected relocation type");
-                *(u64 *)addr += delta;
+                if ( delta )
+                    *(u64 *)addr += delta;
                 break;
             default:
                 blexit(L"Unsupported relocation type");

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File 59a0130c-x86-efi-dont-write-relocs-in-efi_arch_relocate_image-1st-pass.patch of Package xen (Revision 45e6793ee80829b175f0c2513713d660)

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