From 34828425d36b560adfe96430b9b83dfb0f66f2a8 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Fri, 25 Aug 2017 14:07:40 +0200 Subject: [PATCH] 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 Signed-off-by: David Woodhouse --- xen/arch/x86/efi/efi-boot.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/xen/arch/x86/efi/efi-boot.h b/xen/arch/x86/efi/efi-boot.h index bedac5cf17..8d295ff9af 100644 --- 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_image(unsigned long delta) 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"); -- 2.30.2