| Jeremy Fitzhardinge | c44c9ec | 2009-09-21 13:40:42 -0700 | [diff] [blame^] | 1 | #include <linux/spinlock.h> |
| 2 | #include <linux/errno.h> |
| 3 | #include <linux/init.h> |
| 4 | |
| 5 | #include <asm/pgtable.h> |
| 6 | |
| 7 | int nx_enabled; |
| 8 | |
| 9 | #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) |
| 10 | static int disable_nx __cpuinitdata; |
| 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 | __supported_pte_mask |= _PAGE_NX; |
| 26 | disable_nx = 0; |
| 27 | } else if (!strncmp(str, "off", 3)) { |
| 28 | disable_nx = 1; |
| 29 | __supported_pte_mask &= ~_PAGE_NX; |
| 30 | } |
| 31 | return 0; |
| 32 | } |
| 33 | early_param("noexec", noexec_setup); |
| 34 | #endif |
| 35 | |
| 36 | #ifdef CONFIG_X86_PAE |
| 37 | void __init set_nx(void) |
| 38 | { |
| 39 | unsigned int v[4], l, h; |
| 40 | |
| 41 | if (cpu_has_pae && (cpuid_eax(0x80000000) > 0x80000001)) { |
| 42 | cpuid(0x80000001, &v[0], &v[1], &v[2], &v[3]); |
| 43 | |
| 44 | if ((v[3] & (1 << 20)) && !disable_nx) { |
| 45 | rdmsr(MSR_EFER, l, h); |
| 46 | l |= EFER_NX; |
| 47 | wrmsr(MSR_EFER, l, h); |
| 48 | nx_enabled = 1; |
| 49 | __supported_pte_mask |= _PAGE_NX; |
| 50 | } |
| 51 | } |
| 52 | } |
| 53 | #else |
| 54 | void set_nx(void) |
| 55 | { |
| 56 | } |
| 57 | #endif |
| 58 | |
| 59 | #ifdef CONFIG_X86_64 |
| 60 | void __cpuinit check_efer(void) |
| 61 | { |
| 62 | unsigned long efer; |
| 63 | |
| 64 | rdmsrl(MSR_EFER, efer); |
| 65 | if (!(efer & EFER_NX) || disable_nx) |
| 66 | __supported_pte_mask &= ~_PAGE_NX; |
| 67 | } |
| 68 | #endif |
| 69 | |