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x86: Fix vsyscall on gcc 4.5 with -Os

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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@linux.intel.com>
LKML-Reference: <20100618210859.GA10913@basil.fritz.box>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@kernel.org>
This commit is contained in:
Andi Kleen 2010-06-18 23:09:00 +02:00 committed by H. Peter Anvin
parent 6a4f3b5237
commit 124482935f
1 changed files with 1 additions and 1 deletions
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2
arch/x86/include/asm/system.h
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@ -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);