1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/spinlock.h> 3 #include <linux/errno.h> 4 #include <linux/init.h> 5 6 #include <asm/pgtable.h> 7 #include <asm/proto.h> 8 #include <asm/cpufeature.h> 9 10 static int disable_nx; 11 12 /* 13 * noexec = on|off 14 * 15 * Control non-executable mappings for processes. 16 * 17 * on Enable 18 * off Disable 19 */ noexec_setup(char * str)20static int __init noexec_setup(char *str) 21 { 22 if (!str) 23 return -EINVAL; 24 if (!strncmp(str, "on", 2)) { 25 disable_nx = 0; 26 } else if (!strncmp(str, "off", 3)) { 27 disable_nx = 1; 28 } 29 x86_configure_nx(); 30 return 0; 31 } 32 early_param("noexec", noexec_setup); 33 x86_configure_nx(void)34void x86_configure_nx(void) 35 { 36 if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx) 37 __supported_pte_mask |= _PAGE_NX; 38 else 39 __supported_pte_mask &= ~_PAGE_NX; 40 } 41 x86_report_nx(void)42void __init x86_report_nx(void) 43 { 44 if (!boot_cpu_has(X86_FEATURE_NX)) { 45 printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " 46 "missing in CPU!\n"); 47 } else { 48 #if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) 49 if (disable_nx) { 50 printk(KERN_INFO "NX (Execute Disable) protection: " 51 "disabled by kernel command line option\n"); 52 } else { 53 printk(KERN_INFO "NX (Execute Disable) protection: " 54 "active\n"); 55 } 56 #else 57 /* 32bit non-PAE kernel, NX cannot be used */ 58 printk(KERN_NOTICE "Notice: NX (Execute Disable) protection " 59 "cannot be enabled: non-PAE kernel!\n"); 60 #endif 61 } 62 } 63