arch/x86/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/thread_info.h>
  12 #include <linux/sched.h>
  13 #include <linux/gfp.h>
  14 #include <linux/string.h>
  15 #include <linux/elf.h>
  16 #include <linux/mm.h>
  17 #include <linux/err.h>
  18 #include <linux/module.h>
  19 #include <linux/slab.h>
  20
  21 #include <asm/cpufeature.h>
  22 #include <asm/msr.h>
  23 #include <asm/pgtable.h>
  24 #include <asm/unistd.h>
  25 #include <asm/elf.h>
  26 #include <asm/tlbflush.h>
  27 #include <asm/vdso.h>
  28 #include <asm/proto.h>
  29 #include <asm/fixmap.h>
  30 #include <asm/hpet.h>
  31 #include <asm/vvar.h>
  32
  33 #ifdef CONFIG_COMPAT_VDSO
  34 #define VDSO_DEFAULT    0
  35 #else
  36 #define VDSO_DEFAULT    1
  37 #endif
  38
  39 #ifdef CONFIG_X86_64
  40 #define arch_setup_additional_pages     syscall32_setup_pages
  41 #endif
  42
  43 /*
  44  * Should the kernel map a VDSO page into processes and pass its
  45  * address down to glibc upon exec()?
  46  */
  47 unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT;
  48
  49 static int __init vdso32_setup(char *s)
  50 {
  51         vdso32_enabled = simple_strtoul(s, NULL, 0);
  52
  53         if (vdso32_enabled > 1)
  54                 pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n");
  55
  56         return 1;
  57 }
  58
  59 /*
  60  * For consistency, the argument vdso32=[012] affects the 32-bit vDSO
  61  * behavior on both 64-bit and 32-bit kernels.
  62  * On 32-bit kernels, vdso=[012] means the same thing.
  63  */
  64 __setup("vdso32=", vdso32_setup);
  65
  66 #ifdef CONFIG_X86_32
  67 __setup_param("vdso=", vdso_setup, vdso32_setup, 0);
  68 #endif
  69
  70 static struct page **vdso32_pages;
  71 static unsigned vdso32_size;
  72
  73 #ifdef CONFIG_X86_64
  74
  75 #define vdso32_sysenter()       (boot_cpu_has(X86_FEATURE_SYSENTER32))
  76 #define vdso32_syscall()        (boot_cpu_has(X86_FEATURE_SYSCALL32))
  77
  78 #else  /* CONFIG_X86_32 */
  79
  80 #define vdso32_sysenter()       (boot_cpu_has(X86_FEATURE_SEP))
  81 #define vdso32_syscall()        (0)
  82
  83 #endif  /* CONFIG_X86_64 */
  84
  85 int __init sysenter_setup(void)
  86 {
  87         char *vdso32_start, *vdso32_end;
  88         int npages, i;
  89
  90 #ifdef CONFIG_COMPAT
  91         if (vdso32_syscall()) {
  92                 vdso32_start = vdso32_syscall_start;
  93                 vdso32_end = vdso32_syscall_end;
  94                 vdso32_pages = vdso32_syscall_pages;
  95         } else
  96 #endif
  97         if (vdso32_sysenter()) {
  98                 vdso32_start = vdso32_sysenter_start;
  99                 vdso32_end = vdso32_sysenter_end;
 100                 vdso32_pages = vdso32_sysenter_pages;
 101         } else {
 102                 vdso32_start = vdso32_int80_start;
 103                 vdso32_end = vdso32_int80_end;
 104                 vdso32_pages = vdso32_int80_pages;
 105         }
 106
 107         npages = ((vdso32_end - vdso32_start) + PAGE_SIZE - 1) / PAGE_SIZE;
 108         vdso32_size = npages << PAGE_SHIFT;
 109         for (i = 0; i < npages; i++)
 110                 vdso32_pages[i] = virt_to_page(vdso32_start + i*PAGE_SIZE);
 111
 112         patch_vdso32(vdso32_start, vdso32_size);
 113
 114         return 0;
 115 }
 116
 117 /* Setup a VMA at program startup for the vsyscall page */
 118 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 119 {
 120         struct mm_struct *mm = current->mm;
 121         unsigned long addr;
 122         int ret = 0;
 123         struct vm_area_struct *vma;
 124
 125 #ifdef CONFIG_X86_X32_ABI
 126         if (test_thread_flag(TIF_X32))
 127                 return x32_setup_additional_pages(bprm, uses_interp);
 128 #endif
 129
 130         if (vdso32_enabled != 1)  /* Other values all mean "disabled" */
 131                 return 0;
 132
 133         down_write(&mm->mmap_sem);
 134
 135         addr = get_unmapped_area(NULL, 0, vdso32_size + VDSO_OFFSET(VDSO_PREV_PAGES), 0, 0);
 136         if (IS_ERR_VALUE(addr)) {
 137                 ret = addr;
 138                 goto up_fail;
 139         }
 140
 141         addr += VDSO_OFFSET(VDSO_PREV_PAGES);
 142
 143         current->mm->context.vdso = (void *)addr;
 144
 145         /*
 146          * MAYWRITE to allow gdb to COW and set breakpoints
 147          */
 148         ret = install_special_mapping(mm,
 149                         addr,
 150                         vdso32_size,
 151                         VM_READ|VM_EXEC|
 152                         VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 153                         vdso32_pages);
 154
 155         if (ret)
 156                 goto up_fail;
 157
 158         vma = _install_special_mapping(mm,
 159                         addr -  VDSO_OFFSET(VDSO_PREV_PAGES),
 160                         VDSO_OFFSET(VDSO_PREV_PAGES),
 161                         VM_READ,
 162                         NULL);
 163
 164         if (IS_ERR(vma)) {
 165                 ret = PTR_ERR(vma);
 166                 goto up_fail;
 167         }
 168
 169         ret = remap_pfn_range(vma,
 170                 addr - VDSO_OFFSET(VDSO_VVAR_PAGE),
 171                 __pa_symbol(&__vvar_page) >> PAGE_SHIFT,
 172                 PAGE_SIZE,
 173                 PAGE_READONLY);
 174
 175         if (ret)
 176                 goto up_fail;
 177
 178 #ifdef CONFIG_HPET_TIMER
 179         if (hpet_address) {
 180                 ret = io_remap_pfn_range(vma,
 181                         addr - VDSO_OFFSET(VDSO_HPET_PAGE),
 182                         hpet_address >> PAGE_SHIFT,
 183                         PAGE_SIZE,
 184                         pgprot_noncached(PAGE_READONLY));
 185
 186                 if (ret)
 187                         goto up_fail;
 188         }
 189 #endif
 190
 191         current_thread_info()->sysenter_return =
 192                 VDSO32_SYMBOL(addr, SYSENTER_RETURN);
 193
 194   up_fail:
 195         if (ret)
 196                 current->mm->context.vdso = NULL;
 197
 198         up_write(&mm->mmap_sem);
 199
 200         return ret;
 201 }
 202
 203 #ifdef CONFIG_X86_64
 204
 205 subsys_initcall(sysenter_setup);
 206
 207 #ifdef CONFIG_SYSCTL
 208 /* Register vsyscall32 into the ABI table */
 209 #include <linux/sysctl.h>
 210
 211 static struct ctl_table abi_table2[] = {
 212         {
 213                 .procname       = "vsyscall32",
 214                 .data           = &vdso32_enabled,
 215                 .maxlen         = sizeof(int),
 216                 .mode           = 0644,
 217                 .proc_handler   = proc_dointvec
 218         },
 219         {}
 220 };
 221
 222 static struct ctl_table abi_root_table2[] = {
 223         {
 224                 .procname = "abi",
 225                 .mode = 0555,
 226                 .child = abi_table2
 227         },
 228         {}
 229 };
 230
 231 static __init int ia32_binfmt_init(void)
 232 {
 233         register_sysctl_table(abi_root_table2);
 234         return 0;
 235 }
 236 __initcall(ia32_binfmt_init);
 237 #endif
 238
 239 #else  /* CONFIG_X86_32 */
 240
 241 const char *arch_vma_name(struct vm_area_struct *vma)
 242 {
 243         if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso)
 244                 return "[vdso]";
 245         return NULL;
 246 }
 247
 248 struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
 249 {
 250         return NULL;
 251 }
 252
 253 int in_gate_area(struct mm_struct *mm, unsigned long addr)
 254 {
 255         return 0;
 256 }
 257
 258 int in_gate_area_no_mm(unsigned long addr)
 259 {
 260         return 0;
 261 }
 262
 263 #endif  /* CONFIG_X86_64 */