1 /* 2 * (C) Copyright 2002 Linus Torvalds 3 * Portions based on the vdso-randomization code from exec-shield: 4 * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar 5 * 6 * This file contains the needed initializations to support sysenter. 7 */ 8 9 #include <linux/init.h> 10 #include <linux/smp.h> 11 #include <linux/kernel.h> 12 #include <linux/mm_types.h> 13 14 #include <asm/cpufeature.h> 15 #include <asm/processor.h> 16 #include <asm/vdso.h> 17 18 #ifdef CONFIG_COMPAT_VDSO 19 #define VDSO_DEFAULT 0 20 #else 21 #define VDSO_DEFAULT 1 22 #endif 23 24 /* 25 * Should the kernel map a VDSO page into processes and pass its 26 * address down to glibc upon exec()? 27 */ 28 unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT; 29 30 static int __init vdso32_setup(char *s) 31 { 32 vdso32_enabled = simple_strtoul(s, NULL, 0); 33 34 if (vdso32_enabled > 1) 35 pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n"); 36 37 return 1; 38 } 39 40 /* 41 * For consistency, the argument vdso32=[012] affects the 32-bit vDSO 42 * behavior on both 64-bit and 32-bit kernels. 43 * On 32-bit kernels, vdso=[012] means the same thing. 44 */ 45 __setup("vdso32=", vdso32_setup); 46 47 #ifdef CONFIG_X86_32 48 __setup_param("vdso=", vdso_setup, vdso32_setup, 0); 49 #endif 50 51 #ifdef CONFIG_X86_64 52 53 #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SYSENTER32)) 54 #define vdso32_syscall() (boot_cpu_has(X86_FEATURE_SYSCALL32)) 55 56 #else /* CONFIG_X86_32 */ 57 58 #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP)) 59 #define vdso32_syscall() (0) 60 61 #endif /* CONFIG_X86_64 */ 62 63 #if defined(CONFIG_X86_32) || defined(CONFIG_COMPAT) 64 const struct vdso_image *selected_vdso32; 65 #endif 66 67 int __init sysenter_setup(void) 68 { 69 #ifdef CONFIG_COMPAT 70 if (vdso32_syscall()) 71 selected_vdso32 = &vdso_image_32_syscall; 72 else 73 #endif 74 if (vdso32_sysenter()) 75 selected_vdso32 = &vdso_image_32_sysenter; 76 else 77 selected_vdso32 = &vdso_image_32_int80; 78 79 init_vdso_image(selected_vdso32); 80 81 return 0; 82 } 83 84 #ifdef CONFIG_X86_64 85 86 subsys_initcall(sysenter_setup); 87 88 #ifdef CONFIG_SYSCTL 89 /* Register vsyscall32 into the ABI table */ 90 #include <linux/sysctl.h> 91 92 static struct ctl_table abi_table2[] = { 93 { 94 .procname = "vsyscall32", 95 .data = &vdso32_enabled, 96 .maxlen = sizeof(int), 97 .mode = 0644, 98 .proc_handler = proc_dointvec 99 }, 100 {} 101 }; 102 103 static struct ctl_table abi_root_table2[] = { 104 { 105 .procname = "abi", 106 .mode = 0555, 107 .child = abi_table2 108 }, 109 {} 110 }; 111 112 static __init int ia32_binfmt_init(void) 113 { 114 register_sysctl_table(abi_root_table2); 115 return 0; 116 } 117 __initcall(ia32_binfmt_init); 118 #endif /* CONFIG_SYSCTL */ 119 120 #endif /* CONFIG_X86_64 */ 121