1 files changed, 69 insertions, 0 deletions

diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c
new file mode 100644
index 000000000000..513d8ed5d2ec
--- /dev/null
+++ b/arch/x86/mm/setup_nx.c
@@ -0,0 +1,69 @@
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+
+#include <asm/pgtable.h>
+
+int nx_enabled;
+
+#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
+static int disable_nx __cpuinitdata;
+
+/*
+ * noexec = on|off
+ *
+ * Control non-executable mappings for processes.
+ *
+ * on      Enable
+ * off     Disable
+ */
+static int __init noexec_setup(char *str)
+{
+        if (!str)
+                return -EINVAL;
+        if (!strncmp(str, "on", 2)) {
+                __supported_pte_mask |= _PAGE_NX;
+                disable_nx = 0;
+        } else if (!strncmp(str, "off", 3)) {
+                disable_nx = 1;
+                __supported_pte_mask &= ~_PAGE_NX;
+        }
+        return 0;
+}
+early_param("noexec", noexec_setup);
+#endif
+
+#ifdef CONFIG_X86_PAE
+void __init set_nx(void)
+{
+        unsigned int v[4], l, h;
+
+        if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
+                cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
+
+                if ((v[3] & (1 << 20)) && !disable_nx) {
+                        rdmsr(MSR_EFER, l, h);
+                        l |= EFER_NX;
+                        wrmsr(MSR_EFER, l, h);
+                        nx_enabled = 1;
+                        __supported_pte_mask |= _PAGE_NX;
+                }
+        }
+}
+#else
+void set_nx(void)
+{
+}
+#endif
+
+#ifdef CONFIG_X86_64
+void __cpuinit check_efer(void)
+{
+        unsigned long efer;
+
+        rdmsrl(MSR_EFER, efer);
+        if (!(efer & EFER_NX) || disable_nx)
+                __supported_pte_mask &= ~_PAGE_NX;
+}
+#endif
+