[071/140] x86: Fix vsyscall on gcc 4.5 with -Os

From: Greg KH
Date: Fri Jul 30 2010 - 13:39:49 EST

2.6.33-stable review patch. If anyone has any objections, please let us know.


From: Andi Kleen <andi@xxxxxxxxxxxxxx>

commit 124482935fb7fb9303c8a8ab930149c6a93d9910 upstream.

This fixes the -Os breaks with gcc 4.5 bug. rdtsc_barrier needs to be
force inlined, otherwise user space will jump into kernel space and
kill init.

This also addresses http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44129
I believe.

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
LKML-Reference: <20100618210859.GA10913@xxxxxxxxxxxxxxx>
Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

arch/x86/include/asm/system.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/include/asm/system.h
+++ b/arch/x86/include/asm/system.h
@@ -451,7 +451,7 @@ void stop_this_cpu(void *dummy);
* (Could use an alternative three way for this if there was one.)
-static inline void rdtsc_barrier(void)
+static __always_inline void rdtsc_barrier(void)
alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);

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