From: Andi Kleen <andi@firstfloor.org>
Date: Fri, 18 Jun 2010 21:09:00 +0000 (+0200)
Subject: x86: Fix vsyscall on gcc 4.5 with -Os
X-Git-Tag: v2.6.35-rc4~50^2~2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=124482935fb7fb9303c8a8ab930149c6a93d9910;p=platform%2Fkernel%2Flinux-3.10.git

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@linux.intel.com>
LKML-Reference: <20100618210859.GA10913@basil.fritz.box>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: <stable@kernel.org>
---

diff --git a/arch/x86/include/asm/system.h b/arch/x86/include/asm/system.h
index b8fe48e..e7f4d33 100644
--- 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);