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