1 files changed, 62 insertions, 0 deletions
diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c
new file mode 100644
index 000000000..ed5667f51
--- /dev/null
+++ b/arch/x86/mm/setup_nx.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/spinlock.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/pgtable.h>
+
+#include <asm/proto.h>
+#include <asm/cpufeature.h>
+
+static int disable_nx;
+
+/*
+ * 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)) {
+		disable_nx = 0;
+	} else if (!strncmp(str, "off", 3)) {
+		disable_nx = 1;
+	}
+	x86_configure_nx();
+	return 0;
+}
+early_param("noexec", noexec_setup);
+
+void x86_configure_nx(void)
+{
+	if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx)
+		__supported_pte_mask |= _PAGE_NX;
+	else
+		__supported_pte_mask &= ~_PAGE_NX;
+}
+
+void __init x86_report_nx(void)
+{
+	if (!boot_cpu_has(X86_FEATURE_NX)) {
+		printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
+		       "missing in CPU!\n");
+	} else {
+#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
+		if (disable_nx) {
+			printk(KERN_INFO "NX (Execute Disable) protection: "
+			       "disabled by kernel command line option\n");
+		} else {
+			printk(KERN_INFO "NX (Execute Disable) protection: "
+			       "active\n");
+		}
+#else
+		/* 32bit non-PAE kernel, NX cannot be used */
+		printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
+		       "cannot be enabled: non-PAE kernel!\n");
+#endif
+	}
+}