Linux Kernel  3.7.1
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setup_nx.c
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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  */
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  }
28  return 0;
29 }
30 early_param("noexec", noexec_setup);
31 
33 {
34  if (cpu_has_nx && !disable_nx)
36  else
38 }
39 
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 }