efi/x86: Respect 32-bit ABI in efi32_pe_entry()

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
This commit is contained in:
Arvind Sankar 2020-03-08 09:08:41 +01:00 committed by Ingo Molnar
parent 3cdcd6899e
commit 71ff44ac6c
1 changed files with 4 additions and 0 deletions

View File

@ -660,7 +660,11 @@ SYM_DATA(efi_is64, .byte 1)
SYM_FUNC_START(efi32_pe_entry) SYM_FUNC_START(efi32_pe_entry)
pushl %ebp pushl %ebp
pushl %ebx
pushl %edi
call verify_cpu // check for long mode support call verify_cpu // check for long mode support
popl %edi
popl %ebx
testl %eax, %eax testl %eax, %eax
movl $0x80000003, %eax // EFI_UNSUPPORTED movl $0x80000003, %eax // EFI_UNSUPPORTED
jnz 3f jnz 3f