1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * (C) Copyright 2002 Linus Torvalds
4 * Portions based on the vdso-randomization code from exec-shield:
5 * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar
6 *
7 * This file contains the needed initializations to support sysenter.
8 */
9
10 #include <linux/init.h>
11 #include <linux/smp.h>
12 #include <linux/kernel.h>
13 #include <linux/mm_types.h>
14 #include <linux/elf.h>
15
16 #include <asm/processor.h>
17 #include <asm/vdso.h>
18
19 #ifdef CONFIG_COMPAT_VDSO
20 #define VDSO_DEFAULT 0
21 #else
22 #define VDSO_DEFAULT 1
23 #endif
24
25 /*
26 * Should the kernel map a VDSO page into processes and pass its
27 * address down to glibc upon exec()?
28 */
29 unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT;
30
vdso32_setup(char * s)31 static int __init vdso32_setup(char *s)
32 {
33 vdso32_enabled = simple_strtoul(s, NULL, 0);
34
35 if (vdso32_enabled > 1) {
36 pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
37 vdso32_enabled = 0;
38 }
39
40 return 1;
41 }
42
43 /*
44 * For consistency, the argument vdso32=[012] affects the 32-bit vDSO
45 * behavior on both 64-bit and 32-bit kernels.
46 * On 32-bit kernels, vdso=[012] means the same thing.
47 */
48 __setup("vdso32=", vdso32_setup);
49
50 #ifdef CONFIG_X86_32
51 __setup_param("vdso=", vdso_setup, vdso32_setup, 0);
52 #endif
53
54 #ifdef CONFIG_X86_64
55
56 #ifdef CONFIG_SYSCTL
57 /* Register vsyscall32 into the ABI table */
58 #include <linux/sysctl.h>
59
60 static struct ctl_table abi_table2[] = {
61 {
62 .procname = "vsyscall32",
63 .data = &vdso32_enabled,
64 .maxlen = sizeof(int),
65 .mode = 0644,
66 .proc_handler = proc_dointvec_minmax,
67 .extra1 = SYSCTL_ZERO,
68 .extra2 = SYSCTL_ONE,
69 },
70 {}
71 };
72
ia32_binfmt_init(void)73 static __init int ia32_binfmt_init(void)
74 {
75 register_sysctl("abi", abi_table2);
76 return 0;
77 }
78 __initcall(ia32_binfmt_init);
79 #endif /* CONFIG_SYSCTL */
80
81 #endif /* CONFIG_X86_64 */
82