xref: /openbmc/linux/arch/x86/entry/vdso/vdso32-setup.c (revision e7253313)
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 
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 
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 int __init sysenter_setup(void)
54 {
55 	init_vdso_image(&vdso_image_32);
56 
57 	return 0;
58 }
59 
60 #ifdef CONFIG_X86_64
61 
62 subsys_initcall(sysenter_setup);
63 
64 #ifdef CONFIG_SYSCTL
65 /* Register vsyscall32 into the ABI table */
66 #include <linux/sysctl.h>
67 
68 static struct ctl_table abi_table2[] = {
69 	{
70 		.procname	= "vsyscall32",
71 		.data		= &vdso32_enabled,
72 		.maxlen		= sizeof(int),
73 		.mode		= 0644,
74 		.proc_handler	= proc_dointvec_minmax,
75 		.extra1		= SYSCTL_ZERO,
76 		.extra2		= SYSCTL_ONE,
77 	},
78 	{}
79 };
80 
81 static struct ctl_table abi_root_table2[] = {
82 	{
83 		.procname = "abi",
84 		.mode = 0555,
85 		.child = abi_table2
86 	},
87 	{}
88 };
89 
90 static __init int ia32_binfmt_init(void)
91 {
92 	register_sysctl_table(abi_root_table2);
93 	return 0;
94 }
95 __initcall(ia32_binfmt_init);
96 #endif /* CONFIG_SYSCTL */
97 
98 #endif	/* CONFIG_X86_64 */
99