x86: add memory clobber to save/loadsegment
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>
Cc: xen-devel <xen-devel@lists.xensource.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/asm-x86/system.h b/include/asm-x86/system.h
index bacfcee..f686aa6 100644
--- a/include/asm-x86/system.h
+++ b/include/asm-x86/system.h
@@ -153,14 +153,14 @@
"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)
{