x86: read_tsc sync

make native_read_tsc() always non-speculative.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index c42cf12638823a22f1195af42d2eb5553aa0e054..276cb7073ab164100af6e3c8e828490d4cd41c3f 100644 (file)
--- a/arch/x86/kernel/rtc.c
+++ b/arch/x86/kernel/rtc.c
@@ -200,7 +200,10 @@ unsigned long long __vsyscall_fn native_read_tsc(void)
 {
        DECLARE_ARGS(val, low, high);
 
+       rdtsc_barrier();
        asm volatile("rdtsc" : EAX_EDX_RET(val, low, high));
+       rdtsc_barrier();
+
        return EAX_EDX_VAL(val, low, high);
 }
 EXPORT_SYMBOL_GPL(native_read_tsc);