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
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)
64const struct vdso_image *selected_vdso32;
65#endif
66
67int __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
86subsys_initcall(sysenter_setup);
87
88#ifdef CONFIG_SYSCTL
89/* Register vsyscall32 into the ABI table */
90#include <linux/sysctl.h>
91
92static 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
103static struct ctl_table abi_root_table2[] = {
104	{
105		.procname = "abi",
106		.mode = 0555,
107		.child = abi_table2
108	},
109	{}
110};
111
112static __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