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