GNU Linux-libre 4.14.266-gnu1
[releases.git] / arch / x86 / mm / setup_nx.c
1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/spinlock.h>
3 #include <linux/errno.h>
4 #include <linux/init.h>
5
6 #include <asm/pgtable.h>
7 #include <asm/proto.h>
8 #include <asm/cpufeature.h>
9
10 static 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  */
20 static 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 }
32 early_param("noexec", noexec_setup);
33
34 void 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
42 void __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 }