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 
sysenter_setup(void)54 int __init sysenter_setup(void)
55 {
56 	init_vdso_image(&vdso_image_32);
57 
58 	return 0;
59 }
60 
61 #ifdef CONFIG_X86_64
62 
63 subsys_initcall(sysenter_setup);
64 
65 #ifdef CONFIG_SYSCTL
66 /* Register vsyscall32 into the ABI table */
67 #include <linux/sysctl.h>
68 
69 static struct ctl_table abi_table2[] = {
70 	{
71 		.procname	= "vsyscall32",
72 		.data		= &vdso32_enabled,
73 		.maxlen		= sizeof(int),
74 		.mode		= 0644,
75 		.proc_handler	= proc_dointvec_minmax,
76 		.extra1		= SYSCTL_ZERO,
77 		.extra2		= SYSCTL_ONE,
78 	},
79 	{}
80 };
81 
82 static struct ctl_table abi_root_table2[] = {
83 	{
84 		.procname = "abi",
85 		.mode = 0555,
86 		.child = abi_table2
87 	},
88 	{}
89 };
90 
ia32_binfmt_init(void)91 static __init int ia32_binfmt_init(void)
92 {
93 	register_sysctl_table(abi_root_table2);
94 	return 0;
95 }
96 __initcall(ia32_binfmt_init);
97 #endif /* CONFIG_SYSCTL */
98 
99 #endif	/* CONFIG_X86_64 */
100