x86, vdso: Use asm volatile in __getcpu

[deliverable/linux.git] / arch / x86 / include / asm / vgtod.h

diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index e7e9682a33e90f350e0ce5f99c61480755614221..f556c4843aa18af74359dfeb2a41d39d9a2c3bb9 100644 (file)
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -80,9 +80,11 @@ static inline unsigned int __getcpu(void)
 
        /*
         * Load per CPU data from GDT.  LSL is faster than RDTSCP and
-        * works on all CPUs.
+        * works on all CPUs.  This is volatile so that it orders
+        * correctly wrt barrier() and to keep gcc from cleverly
+        * hoisting it out of the calling function.
         */
-       asm("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
+       asm volatile ("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG));
 
        return p;
 }