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
vdso32_setup(char * s)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 vdso32_enabled = 0;
37 }
38
39 return 1;
40 }
41
42 /*
43 * For consistency, the argument vdso32=[012] affects the 32-bit vDSO
44 * behavior on both 64-bit and 32-bit kernels.
45 * On 32-bit kernels, vdso=[012] means the same thing.
46 */
47 __setup("vdso32=", vdso32_setup);
48
49 #ifdef CONFIG_X86_32
50 __setup_param("vdso=", vdso_setup, vdso32_setup, 0);
51 #endif
52
53 #ifdef CONFIG_X86_64
54
55 #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SYSENTER32))
56 #define vdso32_syscall() (boot_cpu_has(X86_FEATURE_SYSCALL32))
57
58 #else /* CONFIG_X86_32 */
59
60 #define vdso32_sysenter() (boot_cpu_has(X86_FEATURE_SEP))
61 #define vdso32_syscall() (0)
62
63 #endif /* CONFIG_X86_64 */
64
65 #if defined(CONFIG_X86_32) || defined(CONFIG_COMPAT)
66 const struct vdso_image *selected_vdso32;
67 #endif
68
sysenter_setup(void)69 int __init sysenter_setup(void)
70 {
71 #ifdef CONFIG_COMPAT
72 if (vdso32_syscall())
73 selected_vdso32 = &vdso_image_32_syscall;
74 else
75 #endif
76 if (vdso32_sysenter())
77 selected_vdso32 = &vdso_image_32_sysenter;
78 else
79 selected_vdso32 = &vdso_image_32_int80;
80
81 init_vdso_image(selected_vdso32);
82
83 return 0;
84 }
85
86 #ifdef CONFIG_X86_64
87
88 subsys_initcall(sysenter_setup);
89
90 #ifdef CONFIG_SYSCTL
91 /* Register vsyscall32 into the ABI table */
92 #include <linux/sysctl.h>
93
94 static const int zero;
95 static const int one = 1;
96
97 static struct ctl_table abi_table2[] = {
98 {
99 .procname = "vsyscall32",
100 .data = &vdso32_enabled,
101 .maxlen = sizeof(int),
102 .mode = 0644,
103 .proc_handler = proc_dointvec_minmax,
104 .extra1 = (int *)&zero,
105 .extra2 = (int *)&one,
106 },
107 {}
108 };
109
110 static struct ctl_table abi_root_table2[] = {
111 {
112 .procname = "abi",
113 .mode = 0555,
114 .child = abi_table2
115 },
116 {}
117 };
118
ia32_binfmt_init(void)119 static __init int ia32_binfmt_init(void)
120 {
121 register_sysctl_table(abi_root_table2);
122 return 0;
123 }
124 __initcall(ia32_binfmt_init);
125 #endif /* CONFIG_SYSCTL */
126
127 #endif /* CONFIG_X86_64 */
128