From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: [PATCH 02 of 36] x86: add memory clobber to
	save/loadsegment
Date: Wed, 25 Jun 2008 00:18:58 -0400
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To: Ingo Molnar <mingo@elte.hu>
Cc: Mark McLoughlin <markmc@redhat.com>, xen-devel <xen-devel@lists.xensource.com>, Eduardo Habkost <ehabkost@redhat.com>, Stephen Tweedie <sct@redhat.com>, x86@kernel.org, LKML <linux-kernel@vger.kernel.org>

Add "memory" clobbers to savesegment and loadsegment, since they can
affect memory accesses and we never want the compiler to reorder them
with respect to memory references.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
---
 include/asm-x86/system.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/asm-x86/system.h b/include/asm-x86/system.h
--- a/include/asm-x86/system.h
+++ b/include/asm-x86/system.h
@@ -157,14 +157,14 @@
 		     "jmp 2b\n"			\
 		     ".previous\n"		\
 		     _ASM_EXTABLE(1b,3b)	\
-		     : :"r" (value), "r" (0))
+		     : :"r" (value), "r" (0) : "memory")
 
 
 /*
  * Save a segment register away
  */
 #define savesegment(seg, value)				\
-	asm volatile("mov %%" #seg ",%0":"=rm" (value))
+	asm("mov %%" #seg ",%0":"=rm" (value) : : "memory")
 
 static inline unsigned long get_limit(unsigned long segment)
 {