[Xen-devel] [PATCH 02 of 36] x86: add memory clobber to save/loadsegment

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

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@xxxxxxxxxx>
---
 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)
 {



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