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

   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  */
  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
  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 int __init sysenter_setup(void)
  52 {
  53         init_vdso_image(&vdso_image_32);
  54
  55         return 0;
  56 }
  57
  58 #ifdef CONFIG_X86_64
  59
  60 subsys_initcall(sysenter_setup);
  61
  62 #ifdef CONFIG_SYSCTL
  63 /* Register vsyscall32 into the ABI table */
  64 #include <linux/sysctl.h>
  65
  66 static struct ctl_table abi_table2[] = {
  67         {
  68                 .procname       = "vsyscall32",
  69                 .data           = &vdso32_enabled,
  70                 .maxlen         = sizeof(int),
  71                 .mode           = 0644,
  72                 .proc_handler   = proc_dointvec
  73         },
  74         {}
  75 };
  76
  77 static struct ctl_table abi_root_table2[] = {
  78         {
  79                 .procname = "abi",
  80                 .mode = 0555,
  81                 .child = abi_table2
  82         },
  83         {}
  84 };
  85
  86 static __init int ia32_binfmt_init(void)
  87 {
  88         register_sysctl_table(abi_root_table2);
  89         return 0;
  90 }
  91 __initcall(ia32_binfmt_init);
  92 #endif /* CONFIG_SYSCTL */
  93
  94 #endif  /* CONFIG_X86_64 */