Commit-ID: 683ad8092cd262a02d01377dd17a29d492438b90
Gitweb: http://git.kernel.org/tip/683ad8092cd262a02d01377dd17a29d492438b90
Author: Linus Torvalds <[email protected]>
AuthorDate: Mon, 16 May 2016 13:05:45 -0700
Committer: Ingo Molnar <[email protected]>
CommitDate: Tue, 17 May 2016 08:25:06 +0200
x86/efi: Fix 7-parameter efi_call()s
Alex Thorlton reported that the SGI/UV code crashes in the efi_call()
code when invoked with 7 parameters, due to:
mov (%rsp), %rax
mov 8(%rax), %rax
...
mov %rax, 40(%rsp)
Offset 8 is only true if CONFIG_FRAME_POINTERS is disabled,
with frame pointers enabled it should be 16.
Furthermore, the SAVE_XMM code saves the old stack pointer, but
that's just crazy. It saves the stack pointer *AFTER* we've done
the:
FRAME_BEGIN
... which will have *changed* the stack pointer, depending on whether
stack frames are enabled or not.
So when the code then does:
mov (%rsp), %rax
... we now move that old stack pointer into %rax, but the offset off that
stack pointer will depend on whether that FRAME_BEGIN saved off %rbp
or not.
So that whole 8-vs-16 offset confusion depends on the frame pointer!
If frame pointers were enabled, it will be 16. If they weren't, it
will be 8.
The right fix is to just get rid of that silly conditional frame
pointer thing, and always use frame pointers in this stub function.
And then we don't need that (odd) load to get the old stack
pointer into %rax - we can just use the frame pointer.
Reported-by: Alex Thorlton <[email protected]>
Tested-by: Alex Thorlton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Brian Gerst <[email protected]>
Cc: Denys Vlasenko <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Vince Weaver <[email protected]>
Link:
http://lkml.kernel.org/r/ca%2b55afzbs2v%[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/platform/efi/efi_stub_64.S | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/arch/x86/platform/efi/efi_stub_64.S
b/arch/x86/platform/efi/efi_stub_64.S
index 92723ae..cd95075 100644
--- a/arch/x86/platform/efi/efi_stub_64.S
+++ b/arch/x86/platform/efi/efi_stub_64.S
@@ -11,7 +11,6 @@
#include <asm/msr.h>
#include <asm/processor-flags.h>
#include <asm/page_types.h>
-#include <asm/frame.h>
#define SAVE_XMM \
mov %rsp, %rax; \
@@ -40,10 +39,10 @@
mov (%rsp), %rsp
ENTRY(efi_call)
- FRAME_BEGIN
+ pushq %rbp
+ movq %rsp, %rbp
SAVE_XMM
- mov (%rsp), %rax
- mov 8(%rax), %rax
+ mov 16(%rbp), %rax
subq $48, %rsp
mov %r9, 32(%rsp)
mov %rax, 40(%rsp)
@@ -53,6 +52,6 @@ ENTRY(efi_call)
call *%rdi
addq $48, %rsp
RESTORE_XMM
- FRAME_END
+ popq %rbp
ret
ENDPROC(efi_call)
