Merge branch 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6.git] / arch / x86 / include / asm / processor.h

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index ac7e79654f3af5b898c023c78ea35ef123594cf5..e08ea043e085c7a35882cf382dc218d17a97b00c 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -713,13 +713,23 @@ static inline void cpu_relax(void)
        rep_nop();
 }
 
-/* Stop speculative execution: */
+/* Stop speculative execution and prefetching of modified code. */
 static inline void sync_core(void)
 {
        int tmp;
 
-       asm volatile("cpuid" : "=a" (tmp) : "0" (1)
-                    : "ebx", "ecx", "edx", "memory");
+#if defined(CONFIG_M386) || defined(CONFIG_M486)
+       if (boot_cpu_data.x86 < 5)
+               /* There is no speculative execution.
+                * jmp is a barrier to prefetching. */
+               asm volatile("jmp 1f\n1:\n" ::: "memory");
+       else
+#endif
+               /* cpuid is a barrier to speculative execution.
+                * Prefetched instructions are automatically
+                * invalidated when modified. */
+               asm volatile("cpuid" : "=a" (tmp) : "0" (1)
+                            : "ebx", "ecx", "edx", "memory");
 }
 
 static inline void __monitor(const void *eax, unsigned long ecx,