[ 65/89] x86, efi: Fix 32-bit EFI handover protocol entry point

[Greg Kroah-Hartman]

3.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Woodhouse <David.Woodhouse@xxxxxxxxx>

commit f791620fa7517e1045742c475a7f005db9a634b8 upstream.

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@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1358513837.2397.247.camel@xxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/boot/compressed/head_32.S |    2 ++
 1 file changed, 2 insertions(+)

--- 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


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