From f5069ba143b04a175b42fe5cf08348155ca59496 Mon Sep 17 00:00:00 2001
From: Fenghua Yu <fenghua.yu@intel.com>
Date: Wed, 11 May 2011 16:51:05 -0700
Subject: [PATCH] --- yaml --- r: 245731 b: refs/heads/master c:
 de5397ad5b9ad22e2401c4dacdf1bb3b19c05679 h: refs/heads/master i:   245729:
 725e39cbf40bafe4e6296299d1c427127e24c6fb   245727:
 e5aafb0bde86f38b03651daa3f3217b269ddbc13 v: v3

---
 [refs]                                    |  2 +-
 trunk/Documentation/kernel-parameters.txt |  4 ++++
 trunk/arch/x86/kernel/cpu/common.c        | 23 +++++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index bdbab414f6b2..f3c88593b6d6 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: dc23c0bccf5eea171c87b3db285d032b9a5f06c4
+refs/heads/master: de5397ad5b9ad22e2401c4dacdf1bb3b19c05679
diff --git a/trunk/Documentation/kernel-parameters.txt b/trunk/Documentation/kernel-parameters.txt
index cc85a9278190..56fb8c16e20b 100644
--- a/trunk/Documentation/kernel-parameters.txt
+++ b/trunk/Documentation/kernel-parameters.txt
@@ -1664,6 +1664,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			noexec=on: enable non-executable mappings (default)
 			noexec=off: disable non-executable mappings
 
+	nosmep		[X86]
+			Disable SMEP (Supervisor Mode Execution Protection)
+			even if it is supported by processor.
+
 	noexec32	[X86-64]
 			This affects only 32-bit executables.
 			noexec32=on: enable non-executable mappings (default)
diff --git a/trunk/arch/x86/kernel/cpu/common.c b/trunk/arch/x86/kernel/cpu/common.c
index 173f3a3fa1a6..cbc70a27430c 100644
--- a/trunk/arch/x86/kernel/cpu/common.c
+++ b/trunk/arch/x86/kernel/cpu/common.c
@@ -254,6 +254,25 @@ static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
 }
 #endif
 
+static int disable_smep __initdata;
+static __init int setup_disable_smep(char *arg)
+{
+	disable_smep = 1;
+	return 1;
+}
+__setup("nosmep", setup_disable_smep);
+
+static __init void setup_smep(struct cpuinfo_x86 *c)
+{
+	if (cpu_has(c, X86_FEATURE_SMEP)) {
+		if (unlikely(disable_smep)) {
+			setup_clear_cpu_cap(X86_FEATURE_SMEP);
+			clear_in_cr4(X86_CR4_SMEP);
+		} else
+			set_in_cr4(X86_CR4_SMEP);
+	}
+}
+
 /*
  * Some CPU features depend on higher CPUID levels, which may not always
  * be available due to CPUID level capping or broken virtualization
@@ -667,6 +686,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 	c->cpu_index = 0;
 #endif
 	filter_cpuid_features(c, false);
+
+	setup_smep(c);
 }
 
 void __init early_cpu_init(void)
@@ -752,6 +773,8 @@ static void __cpuinit generic_identify(struct cpuinfo_x86 *c)
 #endif
 	}
 
+	setup_smep(c);
+
 	get_model_name(c); /* Default name */
 
 	detect_nopl(c);