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>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/x86/kernel/rtc.c b/arch/x86/kernel/rtc.c
index c42cf1263882..276cb7073ab1 100644
--- 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);