linux-kernel - [PATCH] x86: Fix vsyscall on gcc 4.5 with -Os

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Date:	Fri, 18 Jun 2010 23:09:00 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	hpa@...or.com, linux-kernel@...r.kernel.org, ak@...ux.intel.com
Subject: [PATCH] x86: Fix vsyscall on gcc 4.5 with -Os

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: Andi Kleen <ak@...ux.intel.com>

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

Index: linux-2.6.34-ak/arch/x86/include/asm/system.h
===================================================================
--- linux-2.6.34-ak.orig/arch/x86/include/asm/system.h
+++ linux-2.6.34-ak/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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