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- #include <linux/spinlock.h>
- #include <linux/errno.h>
- #include <linux/init.h>
- #include <asm/pgtable.h>
- int nx_enabled;
- #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE)
- static int disable_nx __cpuinitdata;
- /*
- * 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)) {
- __supported_pte_mask |= _PAGE_NX;
- disable_nx = 0;
- } else if (!strncmp(str, "off", 3)) {
- disable_nx = 1;
- __supported_pte_mask &= ~_PAGE_NX;
- }
- return 0;
- }
- early_param("noexec", noexec_setup);
- #endif
- #ifdef CONFIG_X86_PAE
- void __init set_nx(void)
- {
- unsigned int v[4], l, h;
- if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) {
- cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]);
- if ((v[3] & (1 << 20)) && !disable_nx) {
- rdmsr(MSR_EFER, l, h);
- l |= EFER_NX;
- wrmsr(MSR_EFER, l, h);
- nx_enabled = 1;
- __supported_pte_mask |= _PAGE_NX;
- }
- }
- }
- #else
- void set_nx(void)
- {
- }
- #endif
- #ifdef CONFIG_X86_64
- void __cpuinit check_efer(void)
- {
- unsigned long efer;
- rdmsrl(MSR_EFER, efer);
- if (!(efer & EFER_NX) || disable_nx)
- __supported_pte_mask &= ~_PAGE_NX;
- }
- #endif
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