1// SPDX-License-Identifier: GPL-2.0
 2#include <linux/spinlock.h>
 3#include <linux/errno.h>
 4#include <linux/init.h>
 5#include <linux/pgtable.h>
 6
 7#include <asm/proto.h>
 8#include <asm/cpufeature.h>
 9
10static int disable_nx;
11
12/*
13 * noexec = on|off
14 *
15 * Control non-executable mappings for processes.
16 *
17 * on      Enable
18 * off     Disable
19 */
20static int __init noexec_setup(char *str)
21{
22	if (!str)
23		return -EINVAL;
24	if (!strncmp(str, "on", 2)) {
25		disable_nx = 0;
26	} else if (!strncmp(str, "off", 3)) {
27		disable_nx = 1;
28	}
29	x86_configure_nx();
30	return 0;
31}
32early_param("noexec", noexec_setup);
33
34void x86_configure_nx(void)
35{
36	if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx)
37		__supported_pte_mask |= _PAGE_NX;
38	else
39		__supported_pte_mask &= ~_PAGE_NX;
40}
41
42void __init x86_report_nx(void)
43{
44	if (!boot_cpu_has(X86_FEATURE_NX)) {
45		printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
46		       "missing in CPU!\n");
47	} else {
48#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
49		if (disable_nx) {
50			printk(KERN_INFO "NX (Execute Disable) protection: "
51			       "disabled by kernel command line option\n");
52		} else {
53			printk(KERN_INFO "NX (Execute Disable) protection: "
54			       "active\n");
55		}
56#else
57		/* 32bit non-PAE kernel, NX cannot be used */
58		printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
59		       "cannot be enabled: non-PAE kernel!\n");
60#endif
61	}
62}