arch/x86/entry/vdso/vdso32-setup.c

   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 const int zero;
  69 static const int one = 1;
  70
  71 static struct ctl_table abi_table2[] = {
  72         {
  73                 .procname       = "vsyscall32",
  74                 .data           = &vdso32_enabled,
  75                 .maxlen         = sizeof(int),
  76                 .mode           = 0644,
  77                 .proc_handler   = proc_dointvec_minmax,
  78                 .extra1         = (int *)&zero,
  79                 .extra2         = (int *)&one,
  80         },
  81         {}
  82 };
  83
  84 static struct ctl_table abi_root_table2[] = {
  85         {
  86                 .procname = "abi",
  87                 .mode = 0555,
  88                 .child = abi_table2
  89         },
  90         {}
  91 };
  92
  93 static __init int ia32_binfmt_init(void)
  94 {
  95         register_sysctl_table(abi_root_table2);
  96         return 0;
  97 }
  98 __initcall(ia32_binfmt_init);
  99 #endif /* CONFIG_SYSCTL */
 100
 101 #endif  /* CONFIG_X86_64 */