x86, efi: Fix 32-bit EFI handover protocol entry point

If the bootloader calls the EFI handover entry point as a standard function
call, then it'll have a return address on the stack. We need to pop that
before calling efi_main(), or the arguments will all be out of position on
the stack.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/1358513837.2397.247.camel@shinybook.infradead.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Matt Fleming <matt.fleming@intel.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index aa4aaf1b2380..ccb2f4a5f7bd 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -50,8 +50,10 @@ ENTRY(startup_32)
         pushl   %eax
         pushl   %esi
         pushl   %ecx
+        sub     $0x4, %esp
 
         .org 0x30,0x90
+        add     $0x4, %esp
         call    efi_main
         cmpl    $0, %eax
         movl    %eax, %esi