From: Arvind Sankar <nivedita@alum.mit.edu>
Date: Sun, 8 Mar 2020 09:08:41 +0100
Subject: efi/x86: Respect 32-bit ABI in efi32_pe_entry()
Patch-mainline: v5.7-rc1
Git-commit: 71ff44ac6cfaa1d8d3dff6c73636f4fb97b2be10
References: jsc#SLE-16407
verify_cpu() clobbers BX and DI. In case we have to return error, we need
to preserve them to respect the 32-bit calling convention.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200301230436.2246909-3-nivedita@alum.mit.edu
Link: https://lore.kernel.org/r/20200308080859.21568-11-ardb@kernel.org
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
arch/x86/boot/compressed/head_64.S | 4 ++++
1 file changed, 4 insertions(+)
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -658,7 +658,11 @@ SYM_DATA(efi_is64, .byte 1)
SYM_FUNC_START(efi32_pe_entry)
pushl %ebp
+ pushl %ebx
+ pushl %edi
call verify_cpu // check for long mode support
+ popl %edi
+ popl %ebx
testl %eax, %eax
movl $0x80000003, %eax // EFI_UNSUPPORTED
jnz 3f