arch/arm64/kernel/vdso.c

   1 /*
   2  * Additional userspace pages setup for AArch64 and AArch32.
   3  *  - AArch64: vDSO pages setup, vDSO data page update.
   4  *  - AArch32: sigreturn and kuser helpers pages setup.
   5  *
   6  * Copyright (C) 2012 ARM Limited
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  *
  20  * Author: Will Deacon <will.deacon@arm.com>
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <linux/clocksource.h>
  25 #include <linux/elf.h>
  26 #include <linux/err.h>
  27 #include <linux/errno.h>
  28 #include <linux/gfp.h>
  29 #include <linux/mm.h>
  30 #include <linux/sched.h>
  31 #include <linux/signal.h>
  32 #include <linux/slab.h>
  33 #include <linux/timekeeper_internal.h>
  34 #include <linux/vmalloc.h>
  35
  36 #include <asm/cacheflush.h>
  37 #include <asm/signal32.h>
  38 #include <asm/vdso.h>
  39 #include <asm/vdso_datapage.h>
  40
  41 struct vdso_mappings {
  42         unsigned long num_code_pages;
  43         struct vm_special_mapping data_mapping;
  44         struct vm_special_mapping code_mapping;
  45 };
  46
  47 /*
  48  * The vDSO data page.
  49  */
  50 static union {
  51         struct vdso_data        data;
  52         u8                      page[PAGE_SIZE];
  53 } vdso_data_store __page_aligned_data;
  54 struct vdso_data *vdso_data = &vdso_data_store.data;
  55
  56 #ifdef CONFIG_COMPAT
  57 /*
  58  * Create and map the vectors page for AArch32 tasks.
  59  */
  60 #if !defined(CONFIG_VDSO32) || defined(CONFIG_KUSER_HELPERS)
  61 static struct page *vectors_page[] __ro_after_init;
  62 static const struct vm_special_mapping compat_vdso_spec[] = {
  63         {
  64                 /* Must be named [sigpage] for compatibility with arm. */
  65                 .name   = "[sigpage]",
  66                 .pages  = &vectors_page[0],
  67         },
  68 #ifdef CONFIG_KUSER_HELPERS
  69         {
  70                 .name   = "[kuserhelpers]",
  71                 .pages  = &vectors_page[1],
  72         },
  73 #endif
  74 };
  75 static struct page *vectors_page[ARRAY_SIZE(compat_vdso_spec)] __ro_after_init;
  76 #endif
  77
  78 static int __init alloc_vectors_page(void)
  79 {
  80 #ifdef CONFIG_KUSER_HELPERS
  81         extern char __kuser_helper_start[], __kuser_helper_end[];
  82         size_t kuser_sz = __kuser_helper_end - __kuser_helper_start;
  83         unsigned long kuser_vpage;
  84 #endif
  85
  86 #ifndef CONFIG_VDSO32
  87         extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
  88         size_t sigret_sz =
  89                 __aarch32_sigret_code_end - __aarch32_sigret_code_start;
  90         unsigned long sigret_vpage;
  91
  92         sigret_vpage = get_zeroed_page(GFP_ATOMIC);
  93         if (!sigret_vpage)
  94                 return -ENOMEM;
  95 #endif
  96
  97 #ifdef CONFIG_KUSER_HELPERS
  98         kuser_vpage = get_zeroed_page(GFP_ATOMIC);
  99         if (!kuser_vpage) {
 100 #ifndef CONFIG_VDSO32
 101                 free_page(sigret_vpage);
 102 #endif
 103                 return -ENOMEM;
 104         }
 105 #endif
 106
 107 #ifndef CONFIG_VDSO32
 108         /* sigreturn code */
 109         memcpy((void *)sigret_vpage, __aarch32_sigret_code_start, sigret_sz);
 110         flush_icache_range(sigret_vpage, sigret_vpage + PAGE_SIZE);
 111         vectors_page[0] = virt_to_page(sigret_vpage);
 112 #endif
 113
 114 #ifdef CONFIG_KUSER_HELPERS
 115         /* kuser helpers */
 116         memcpy((void *)kuser_vpage + 0x1000 - kuser_sz, __kuser_helper_start,
 117                 kuser_sz);
 118         flush_icache_range(kuser_vpage, kuser_vpage + PAGE_SIZE);
 119         vectors_page[1] = virt_to_page(kuser_vpage);
 120 #endif
 121
 122         return 0;
 123 }
 124 arch_initcall(alloc_vectors_page);
 125
 126 #ifndef CONFIG_VDSO32
 127 int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 128 {
 129         struct mm_struct *mm = current->mm;
 130         unsigned long addr;
 131         void *ret;
 132
 133         down_write(&mm->mmap_sem);
 134         addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
 135         if (IS_ERR_VALUE(addr)) {
 136                 ret = ERR_PTR(addr);
 137                 goto out;
 138         }
 139
 140         ret = _install_special_mapping(mm, addr, PAGE_SIZE,
 141                                        VM_READ|VM_EXEC|
 142                                        VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 143                                        &compat_vdso_spec[0]);
 144         if (IS_ERR(ret))
 145                 goto out;
 146
 147         current->mm->context.vdso = (void *)addr;
 148
 149 #ifdef CONFIG_KUSER_HELPERS
 150         /* Map the kuser helpers at the ABI-defined high address. */
 151         ret = _install_special_mapping(mm, AARCH32_KUSER_HELPERS_BASE,
 152                                        PAGE_SIZE,
 153                                        VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
 154                                        &compat_vdso_spec[1]);
 155 #endif
 156 out:
 157         up_write(&mm->mmap_sem);
 158
 159         return PTR_ERR_OR_ZERO(ret);
 160 }
 161 #endif /* !CONFIG_VDSO32 */
 162 #endif /* CONFIG_COMPAT */
 163
 164 static int __init vdso_mappings_init(const char *name,
 165                                      const char *code_start,
 166                                      const char *code_end,
 167                                      struct vdso_mappings *mappings)
 168 {
 169         unsigned long i, vdso_pages;
 170         struct page **vdso_pagelist;
 171         unsigned long pfn;
 172
 173         if (memcmp(code_start, "\177ELF", 4)) {
 174                 pr_err("%s is not a valid ELF object!\n", name);
 175                 return -EINVAL;
 176         }
 177
 178         vdso_pages = (code_end - code_start) >> PAGE_SHIFT;
 179         pr_info("%s: %ld pages (%ld code @ %p, %ld data @ %p)\n",
 180                 name, vdso_pages + 1, vdso_pages, code_start, 1L,
 181                 vdso_data);
 182
 183         /*
 184          * Allocate space for storing pointers to the vDSO code pages + the
 185          * data page. The pointers must have the same lifetime as the mappings,
 186          * which are static, so there is no need to keep track of the pointer
 187          * array to free it.
 188          */
 189         vdso_pagelist = kmalloc_array(vdso_pages + 1, sizeof(struct page *),
 190                                       GFP_KERNEL);
 191         if (vdso_pagelist == NULL)
 192                 return -ENOMEM;
 193
 194         /* Grab the vDSO data page. */
 195         vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
 196
 197         /* Grab the vDSO code pages. */
 198         pfn = sym_to_pfn(code_start);
 199
 200         for (i = 0; i < vdso_pages; i++)
 201                 vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
 202
 203         /* Populate the special mapping structures */
 204         mappings->data_mapping = (struct vm_special_mapping) {
 205                 .name   = "[vvar]",
 206                 .pages  = &vdso_pagelist[0],
 207         };
 208
 209         mappings->code_mapping = (struct vm_special_mapping) {
 210                 .name   = "[vdso]",
 211                 .pages  = &vdso_pagelist[1],
 212         };
 213
 214         mappings->num_code_pages = vdso_pages;
 215         return 0;
 216 }
 217
 218 #ifdef CONFIG_COMPAT
 219 #ifdef CONFIG_VDSO32
 220
 221 static struct vdso_mappings vdso32_mappings __ro_after_init;
 222
 223 static int __init vdso32_init(void)
 224 {
 225         extern char vdso32_start[], vdso32_end[];
 226
 227         return vdso_mappings_init("vdso32", vdso32_start, vdso32_end,
 228                                   &vdso32_mappings);
 229 }
 230 arch_initcall(vdso32_init);
 231
 232 #endif /* CONFIG_VDSO32 */
 233 #endif /* CONFIG_COMPAT */
 234
 235 static struct vdso_mappings vdso_mappings __ro_after_init;
 236
 237 static int __init vdso_init(void)
 238 {
 239         extern char vdso_start[], vdso_end[];
 240
 241         return vdso_mappings_init("vdso", vdso_start, vdso_end,
 242                                   &vdso_mappings);
 243 }
 244
 245 arch_initcall(vdso_init);
 246
 247 static int vdso_setup(struct mm_struct *mm,
 248                       const struct vdso_mappings *mappings)
 249 {
 250         unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
 251         void *ret;
 252
 253         vdso_text_len = mappings->num_code_pages << PAGE_SHIFT;
 254         /* Be sure to map the data page */
 255         vdso_mapping_len = vdso_text_len + PAGE_SIZE;
 256
 257         vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
 258         if (IS_ERR_VALUE(vdso_base))
 259                 return PTR_ERR_OR_ZERO(ERR_PTR(vdso_base));
 260         ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
 261                                        VM_READ|VM_MAYREAD,
 262                                        &mappings->data_mapping);
 263         if (IS_ERR(ret))
 264                 return PTR_ERR_OR_ZERO(ret);
 265
 266         vdso_base += PAGE_SIZE;
 267         ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
 268                                        VM_READ|VM_EXEC|
 269                                        VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 270                                        &mappings->code_mapping);
 271         if (!IS_ERR(ret))
 272                 mm->context.vdso = (void *)vdso_base;
 273         return PTR_ERR_OR_ZERO(ret);
 274 }
 275
 276 #ifdef CONFIG_COMPAT
 277 #ifdef CONFIG_VDSO32
 278 int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 279 {
 280         struct mm_struct *mm = current->mm;
 281         void *ret;
 282
 283         down_write(&mm->mmap_sem);
 284
 285         ret = ERR_PTR(vdso_setup(mm, &vdso32_mappings));
 286 #ifdef CONFIG_KUSER_HELPERS
 287         if (!IS_ERR(ret))
 288                 /* Map the kuser helpers at the ABI-defined high address. */
 289                 ret = _install_special_mapping(mm, AARCH32_KUSER_HELPERS_BASE,
 290                                                PAGE_SIZE,
 291                                                VM_READ|VM_EXEC|
 292                                                VM_MAYREAD|VM_MAYEXEC,
 293                                                &compat_vdso_spec[1]);
 294 #endif
 295
 296         up_write(&mm->mmap_sem);
 297
 298         return PTR_ERR_OR_ZERO(ret);
 299 }
 300 #endif /* CONFIG_VDSO32 */
 301 #endif /* CONFIG_COMPAT */
 302
 303 int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 304 {
 305         struct mm_struct *mm = current->mm;
 306         int ret;
 307
 308         down_write(&mm->mmap_sem);
 309         ret = vdso_setup(mm, &vdso_mappings);
 310         up_write(&mm->mmap_sem);
 311         return ret;
 312 }
 313
 314 /*
 315  * Update the vDSO data page to keep in sync with kernel timekeeping.
 316  */
 317 void update_vsyscall(struct timekeeper *tk)
 318 {
 319         u32 use_syscall = strcmp(tk->tkr_mono.clock->name, "arch_sys_counter");
 320
 321         ++vdso_data->tb_seq_count;
 322         smp_wmb();
 323
 324         vdso_data->use_syscall                  = use_syscall;
 325         vdso_data->xtime_coarse_sec             = tk->xtime_sec;
 326         vdso_data->xtime_coarse_nsec            = tk->tkr_mono.xtime_nsec >>
 327                                                         tk->tkr_mono.shift;
 328         vdso_data->wtm_clock_sec                = tk->wall_to_monotonic.tv_sec;
 329         vdso_data->wtm_clock_nsec               = tk->wall_to_monotonic.tv_nsec;
 330
 331         if (!use_syscall) {
 332                 struct timespec btm = ktime_to_timespec(tk->offs_boot);
 333
 334                 /* tkr_mono.cycle_last == tkr_raw.cycle_last */
 335                 vdso_data->cs_cycle_last        = tk->tkr_mono.cycle_last;
 336                 vdso_data->raw_time_sec         = tk->raw_sec;
 337                 vdso_data->raw_time_nsec        = tk->tkr_raw.xtime_nsec;
 338                 vdso_data->xtime_clock_sec      = tk->xtime_sec;
 339                 vdso_data->xtime_clock_snsec    = tk->tkr_mono.xtime_nsec;
 340                 vdso_data->cs_mono_mult         = tk->tkr_mono.mult;
 341                 vdso_data->cs_raw_mult          = tk->tkr_raw.mult;
 342                 /* tkr_mono.shift == tkr_raw.shift */
 343                 vdso_data->cs_shift             = tk->tkr_mono.shift;
 344                 vdso_data->btm_sec              = btm.tv_sec;
 345                 vdso_data->btm_nsec             = btm.tv_nsec;
 346         }
 347
 348         smp_wmb();
 349         ++vdso_data->tb_seq_count;
 350 }
 351
 352 void update_vsyscall_tz(void)
 353 {
 354         vdso_data->tz_minuteswest       = sys_tz.tz_minuteswest;
 355         vdso_data->tz_dsttime           = sys_tz.tz_dsttime;
 356 }