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/processor.h>
  15 #include <asm/vdso.h>
  16
  17 #ifdef CONFIG_COMPAT_VDSO
  18 #define VDSO_DEFAULT    0
  19 #else
  20 #define VDSO_DEFAULT    1
  21 #endif
  22
  23 /*
  24  * Should the kernel map a VDSO page into processes and pass its
  25  * address down to glibc upon exec()?
  26  */
  27 unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT;
  28
  29 static int __init vdso32_setup(char *s)
  30 {
  31         vdso32_enabled = simple_strtoul(s, NULL, 0);
  32
  33         if (vdso32_enabled > 1) {
  34                 pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
  35                 vdso32_enabled = 0;
  36         }
  37
  38         return 1;
  39 }
  40
  41 /*
  42  * For consistency, the argument vdso32=[012] affects the 32-bit vDSO
  43  * behavior on both 64-bit and 32-bit kernels.
  44  * On 32-bit kernels, vdso=[012] means the same thing.
  45  */
  46 __setup("vdso32=", vdso32_setup);
  47
  48 #ifdef CONFIG_X86_32
  49 __setup_param("vdso=", vdso_setup, vdso32_setup, 0);
  50 #endif
  51
  52 int __init sysenter_setup(void)
  53 {
  54         init_vdso_image(&vdso_image_32);
  55
  56         return 0;
  57 }
  58
  59 #ifdef CONFIG_X86_64
  60
  61 subsys_initcall(sysenter_setup);
  62
  63 #ifdef CONFIG_SYSCTL
  64 /* Register vsyscall32 into the ABI table */
  65 #include <linux/sysctl.h>
  66
  67 static const int zero;
  68 static const int one = 1;
  69
  70 static struct ctl_table abi_table2[] = {
  71         {
  72                 .procname       = "vsyscall32",
  73                 .data           = &vdso32_enabled,
  74                 .maxlen         = sizeof(int),
  75                 .mode           = 0644,
  76                 .proc_handler   = proc_dointvec_minmax,
  77                 .extra1         = (int *)&zero,
  78                 .extra2         = (int *)&one,
  79         },
  80         {}
  81 };
  82
  83 static struct ctl_table abi_root_table2[] = {
  84         {
  85                 .procname = "abi",
  86                 .mode = 0555,
  87                 .child = abi_table2
  88         },
  89         {}
  90 };
  91
  92 static __init int ia32_binfmt_init(void)
  93 {
  94         register_sysctl_table(abi_root_table2);
  95         return 0;
  96 }
  97 __initcall(ia32_binfmt_init);
  98 #endif /* CONFIG_SYSCTL */
  99
 100 #endif  /* CONFIG_X86_64 */