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#include <linux/sched.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <asm/pgtable.h>
#include <asm/proto.h>
#ifdef CONFIG_X86_32
int disable_nx; /* referenced by load_elf_binary() */
#else
int disable_nx __cpuinitdata;
#endif
/*
* noexec = on|off
*
* Control non-executable mappings for processes.
*
* on Enable
* off Disable
*/
static int __init noexec_setup(char *str)
{
if (!str)
return -EINVAL;
if (!strncmp(str, "on", 2)) {
disable_nx = 0;
} else if (!strncmp(str, "off", 3)) {
disable_nx = 1;
}
x86_configure_nx();
return 0;
}
early_param("noexec", noexec_setup);
void __cpuinit x86_configure_nx(void)
{
if (cpu_has_nx && !disable_nx)
__supported_pte_mask |= _PAGE_NX;
else
__supported_pte_mask &= ~_PAGE_NX;
}
void __init x86_report_nx(void)
{
int nx_emulation = 0;
if (!cpu_has_nx) {
printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
"missing in CPU!\n");
nx_emulation = 1;
} else {
#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
if (disable_nx) {
printk(KERN_INFO "NX (Execute Disable) protection: "
"disabled by kernel command line option\n");
} else {
printk(KERN_INFO "NX (Execute Disable) protection: "
"active\n");
}
#else
/* 32bit non-PAE kernel, NX cannot be used */
printk(KERN_NOTICE "Notice: NX (Execute Disable) protection "
"cannot be enabled in hardware: non-PAE kernel!\n");
nx_emulation = 1;
#endif
}
if (nx_emulation) {
#ifdef CONFIG_X86_32
if (!disable_nx)
printk(KERN_INFO "NX (Execute Disable) protection: "
"approximated by x86 segment limits\n");
else
printk(KERN_INFO "NX (Execute Disable) protection: "
"approximation disabled by kernel command "
"line option\n");
#endif
}
}
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