linux-kernel - [045/165] x86: Fix vsyscall on gcc 4.5 with -Os

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Message-Id: <20100730171503.743348082@clark.site>
Date:	Fri, 30 Jul 2010 10:14:33 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Andi Kleen <ak@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: [045/165] x86: Fix vsyscall on gcc 4.5 with -Os

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

------------------

From: Andi Kleen <andi@...stfloor.org>

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@...ux.intel.com>
LKML-Reference: <20100618210859.GA10913@...il.fritz.box>
Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 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
@@ -449,7 +449,7 @@ 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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