From: Marcelo Tosatti <mtosatti@redhat.com>
Date: Wed, 28 Nov 2012 01:28:49 +0000 (-0200)
Subject: x86: pvclock: make sure rdtsc doesnt speculate out of region
X-Git-Tag: v3.8-rc1~121^2~36
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b01578de45614c085be319229a52774b61ffe6fb;p=platform%2Fkernel%2Flinux-exynos.git

x86: pvclock: make sure rdtsc doesnt speculate out of region

Originally from Jeremy Fitzhardinge.

pvclock_get_time_values, which contains the memory barriers
will be removed by next patch.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---

diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index 42eb330..12e47e2 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -97,10 +97,10 @@ cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
 
 	do {
 		version = pvclock_get_time_values(&shadow, src);
-		barrier();
+		rdtsc_barrier();
 		offset = pvclock_get_nsec_offset(&shadow);
 		ret = shadow.system_timestamp + offset;
-		barrier();
+		rdtsc_barrier();
 	} while (version != src->version);
 
 	if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&