diff options
| author | Josh Poimboeuf <[email protected]> | 2016-09-23 16:49:39 -0500 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2016-09-24 09:30:03 +0200 |
| commit | 317c2ce77d8ab73c24f4fb9c75e5bb441fbe3e30 (patch) | |
| tree | 343eb3fa3f0aa8a7fb11c136afa4281f0776fe16 | |
| parent | 71f5443ebb1227c22e8decbcd28a1ea6deaf8257 (diff) | |
x86/alternatives: Add stack frame dependency to alternative_call_2()
Linus reported the following objtool warning:
kernel/signal.o: warning: objtool: .altinstr_replacement+0x54: call without frame pointer save/setup
The warning is valid. It's caused by the fact that gcc placed the call
instruction in alternative_call_2()'s inline asm before the frame
pointer setup, which breaks frame pointer convention and can result in a
bad stack trace.
Force a stack frame to be created before the call instruction by listing
the stack pointer as an output operand in the inline asm statement.
Reported-and-tested-by: Linus Torvalds <[email protected]>
Signed-off-by: Josh Poimboeuf <[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: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: http://lkml.kernel.org/r/20160923214939.j5o7c67nhepzmh3t@treble
Signed-off-by: Ingo Molnar <[email protected]>
| -rw-r--r-- | arch/x86/include/asm/alternative.h | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h index e77a6443104f..1b020381ab38 100644 --- a/arch/x86/include/asm/alternative.h +++ b/arch/x86/include/asm/alternative.h @@ -217,10 +217,14 @@ static inline int alternatives_text_reserved(void *start, void *end) */ #define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2, \ output, input...) \ +{ \ + register void *__sp asm(_ASM_SP); \ asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\ "call %P[new2]", feature2) \ - : output : [old] "i" (oldfunc), [new1] "i" (newfunc1), \ - [new2] "i" (newfunc2), ## input) + : output, "+r" (__sp) \ + : [old] "i" (oldfunc), [new1] "i" (newfunc1), \ + [new2] "i" (newfunc2), ## input); \ +} /* * use this macro(s) if you need more than one output parameter |