From 2aedbbcdd0743d22166afbd07561d58b60bd6d99 Mon Sep 17 00:00:00 2001
From: Andi Kleen <ak@suse.de>
Date: Wed, 30 Jan 2008 13:32:38 +0100
Subject: [PATCH] --- yaml --- r: 80152 b: refs/heads/master c:
 fde1b3fa947c2512e3715962ebb1d3a6a9b9bb7d h: refs/heads/master v: v3

---
 [refs]                         |  2 +-
 trunk/include/asm-x86/system.h | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index cbb0aa00e2bc..7cf68559acc3 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2a10e7c41254941cac87be1eccdcb6379ce097f5
+refs/heads/master: fde1b3fa947c2512e3715962ebb1d3a6a9b9bb7d
diff --git a/trunk/include/asm-x86/system.h b/trunk/include/asm-x86/system.h
index 6c7d1fda4995..39474f2957a3 100644
--- a/trunk/include/asm-x86/system.h
+++ b/trunk/include/asm-x86/system.h
@@ -5,6 +5,7 @@
 #include <asm/segment.h>
 #include <asm/cpufeature.h>
 #include <asm/cmpxchg.h>
+#include <asm/nops.h>
 
 #include <linux/kernel.h>
 #include <linux/irqflags.h>
@@ -395,5 +396,17 @@ void default_idle(void);
 #define set_mb(var, value) do { var = value; barrier(); } while (0)
 #endif
 
+/*
+ * Stop RDTSC speculation. This is needed when you need to use RDTSC
+ * (or get_cycles or vread that possibly accesses the TSC) in a defined
+ * code region.
+ *
+ * (Could use an alternative three way for this if there was one.)
+ */
+static inline void rdtsc_barrier(void)
+{
+	alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
+	alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
+}
 
 #endif