source: src/linux/universal/linux-3.18/arch/x86/vdso/vdso32-setup.c @ 31885

Last change on this file since 31885 was 31885, checked in by brainslayer, 5 weeks ago

update

File size: 2.6 KB
Line 
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 */
28unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT;
29
30static 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)
66const struct vdso_image *selected_vdso32;
67#endif
68
69int __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
88subsys_initcall(sysenter_setup);
89
90#ifdef CONFIG_SYSCTL
91/* Register vsyscall32 into the ABI table */
92#include <linux/sysctl.h>
93
94static const int zero;
95static const int one = 1;
96
97static 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
110static struct ctl_table abi_root_table2[] = {
111        {
112                .procname = "abi",
113                .mode = 0555,
114                .child = abi_table2
115        },
116        {}
117};
118
119static __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 */
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