i386: NX emulation

[linux-flexiantxendom0-natty.git] / arch / x86 / kernel / cpu / common.c

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 1d59834..20d704f 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -825,6 +825,22 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
        /* Filter out anything that depends on CPUID levels we don't have */
        filter_cpuid_features(c, true);
 
+#ifdef CONFIG_X86_32
+       /*
+        *  emulation of NX with segment limits unfortunately means
+        *  we have to disable the fast system calls, due to the way that
+        *  sysexit clears the segment limits on return.
+        *  If we have either disabled exec-shield on the boot command line,
+        *  or we have NX, then we don't need to do this.
+        */
+       if (exec_shield != 0) {
+#ifdef CONFIG_X86_PAE
+               if (!test_cpu_cap(c, X86_FEATURE_NX))
+#endif
+                       clear_cpu_cap(c, X86_FEATURE_SEP);
+       }
+#endif
+
        /* If the model name is still unset, do table lookup. */
        if (!c->x86_model_id[0]) {
                const char *p;