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Commit 12448293 authored by Andi Kleen's avatar Andi Kleen Committed by H. Peter Anvin
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x86: Fix vsyscall on gcc 4.5 with -Os 

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: default avatarAndi Kleen <ak@linux.intel.com>
LKML-Reference: <20100618210859.GA10913@basil.fritz.box>
Signed-off-by: default avatarH. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@kernel.org>
parent 6a4f3b52

arch/x86/include/asm/system.h

+1 −1
Original line number Diff line number Diff line
@@ -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);