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 extern char vdso_start, vdso_end;
  42 static unsigned long vdso_pages;
  43 static struct page **vdso_pagelist;
  44
  45 /*
  46  * The vDSO data page.
  47  */
  48 static union {
  49         struct vdso_data        data;
  50         u8                      page[PAGE_SIZE];
  51 } vdso_data_store __page_aligned_data;
  52 struct vdso_data *vdso_data = &vdso_data_store.data;
  53
  54 #ifdef CONFIG_COMPAT
  55 /*
  56  * Create and map the vectors page for AArch32 tasks.
  57  */
  58 static struct page *vectors_page[] __ro_after_init;
  59 static const struct vm_special_mapping compat_vdso_spec[] = {
  60         {
  61                 /* Must be named [sigpage] for compatibility with arm. */
  62                 .name   = "[sigpage]",
  63                 .pages  = &vectors_page[0],
  64         },
  65 #ifdef CONFIG_KUSER_HELPERS
  66         {
  67                 .name   = "[kuserhelpers]",
  68                 .pages  = &vectors_page[1],
  69         },
  70 #endif
  71 };
  72 static struct page *vectors_page[ARRAY_SIZE(compat_vdso_spec)] __ro_after_init;
  73
  74 static int __init alloc_vectors_page(void)
  75 {
  76 #ifdef CONFIG_KUSER_HELPERS
  77         extern char __kuser_helper_start[], __kuser_helper_end[];
  78         size_t kuser_sz = __kuser_helper_end - __kuser_helper_start;
  79         unsigned long kuser_vpage;
  80 #endif
  81
  82         extern char __aarch32_sigret_code_start[], __aarch32_sigret_code_end[];
  83         size_t sigret_sz =
  84                 __aarch32_sigret_code_end - __aarch32_sigret_code_start;
  85         unsigned long sigret_vpage;
  86
  87         sigret_vpage = get_zeroed_page(GFP_ATOMIC);
  88         if (!sigret_vpage)
  89                 return -ENOMEM;
  90
  91 #ifdef CONFIG_KUSER_HELPERS
  92         kuser_vpage = get_zeroed_page(GFP_ATOMIC);
  93         if (!kuser_vpage) {
  94                 free_page(sigret_vpage);
  95                 return -ENOMEM;
  96         }
  97 #endif
  98
  99         /* sigreturn code */
 100         memcpy((void *)sigret_vpage, __aarch32_sigret_code_start, sigret_sz);
 101         flush_icache_range(sigret_vpage, sigret_vpage + PAGE_SIZE);
 102         vectors_page[0] = virt_to_page(sigret_vpage);
 103
 104 #ifdef CONFIG_KUSER_HELPERS
 105         /* kuser helpers */
 106         memcpy((void *)kuser_vpage + 0x1000 - kuser_sz, __kuser_helper_start,
 107                 kuser_sz);
 108         flush_icache_range(kuser_vpage, kuser_vpage + PAGE_SIZE);
 109         vectors_page[1] = virt_to_page(kuser_vpage);
 110 #endif
 111
 112         return 0;
 113 }
 114 arch_initcall(alloc_vectors_page);
 115
 116 int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 117 {
 118         struct mm_struct *mm = current->mm;
 119         unsigned long addr;
 120         void *ret;
 121
 122         down_write(&mm->mmap_sem);
 123         addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
 124         if (IS_ERR_VALUE(addr)) {
 125                 ret = ERR_PTR(addr);
 126                 goto out;
 127         }
 128
 129         ret = _install_special_mapping(mm, addr, PAGE_SIZE,
 130                                        VM_READ|VM_EXEC|
 131                                        VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 132                                        &compat_vdso_spec[0]);
 133         if (IS_ERR(ret))
 134                 goto out;
 135
 136         current->mm->context.vdso = (void *)addr;
 137
 138 #ifdef CONFIG_KUSER_HELPERS
 139         /* Map the kuser helpers at the ABI-defined high address. */
 140         ret = _install_special_mapping(mm, AARCH32_KUSER_HELPERS_BASE,
 141                                        PAGE_SIZE,
 142                                        VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
 143                                        &compat_vdso_spec[1]);
 144 #endif
 145 out:
 146         up_write(&mm->mmap_sem);
 147
 148         return PTR_ERR_OR_ZERO(ret);
 149 }
 150 #endif /* CONFIG_COMPAT */
 151
 152 static struct vm_special_mapping vdso_spec[2];
 153
 154 static int __init vdso_init(void)
 155 {
 156         int i;
 157         unsigned long pfn;
 158
 159         if (memcmp(&vdso_start, "\177ELF", 4)) {
 160                 pr_err("vDSO is not a valid ELF object!\n");
 161                 return -EINVAL;
 162         }
 163
 164         vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
 165         pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
 166                 vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data);
 167
 168         /* Allocate the vDSO pagelist, plus a page for the data. */
 169         vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
 170                                 GFP_KERNEL);
 171         if (vdso_pagelist == NULL)
 172                 return -ENOMEM;
 173
 174         /* Grab the vDSO data page. */
 175         vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data));
 176
 177
 178         /* Grab the vDSO code pages. */
 179         pfn = sym_to_pfn(&vdso_start);
 180
 181         for (i = 0; i < vdso_pages; i++)
 182                 vdso_pagelist[i + 1] = pfn_to_page(pfn + i);
 183
 184         /* Populate the special mapping structures */
 185         vdso_spec[0] = (struct vm_special_mapping) {
 186                 .name   = "[vvar]",
 187                 .pages  = vdso_pagelist,
 188         };
 189
 190         vdso_spec[1] = (struct vm_special_mapping) {
 191                 .name   = "[vdso]",
 192                 .pages  = &vdso_pagelist[1],
 193         };
 194
 195         return 0;
 196 }
 197 arch_initcall(vdso_init);
 198
 199 int arch_setup_additional_pages(struct linux_binprm *bprm,
 200                                 int uses_interp)
 201 {
 202         struct mm_struct *mm = current->mm;
 203         unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
 204         void *ret;
 205
 206         vdso_text_len = vdso_pages << PAGE_SHIFT;
 207         /* Be sure to map the data page */
 208         vdso_mapping_len = vdso_text_len + PAGE_SIZE;
 209
 210         down_write(&mm->mmap_sem);
 211         vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
 212         if (IS_ERR_VALUE(vdso_base)) {
 213                 ret = ERR_PTR(vdso_base);
 214                 goto up_fail;
 215         }
 216         ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
 217                                        VM_READ|VM_MAYREAD,
 218                                        &vdso_spec[0]);
 219         if (IS_ERR(ret))
 220                 goto up_fail;
 221
 222         vdso_base += PAGE_SIZE;
 223         mm->context.vdso = (void *)vdso_base;
 224         ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
 225                                        VM_READ|VM_EXEC|
 226                                        VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 227                                        &vdso_spec[1]);
 228         if (IS_ERR(ret))
 229                 goto up_fail;
 230
 231
 232         up_write(&mm->mmap_sem);
 233         return 0;
 234
 235 up_fail:
 236         mm->context.vdso = NULL;
 237         up_write(&mm->mmap_sem);
 238         return PTR_ERR(ret);
 239 }
 240
 241 /*
 242  * Update the vDSO data page to keep in sync with kernel timekeeping.
 243  */
 244 void update_vsyscall(struct timekeeper *tk)
 245 {
 246         u32 use_syscall = strcmp(tk->tkr_mono.clock->name, "arch_sys_counter");
 247
 248         ++vdso_data->tb_seq_count;
 249         smp_wmb();
 250
 251         vdso_data->use_syscall                  = use_syscall;
 252         vdso_data->xtime_coarse_sec             = tk->xtime_sec;
 253         vdso_data->xtime_coarse_nsec            = tk->tkr_mono.xtime_nsec >>
 254                                                         tk->tkr_mono.shift;
 255         vdso_data->wtm_clock_sec                = tk->wall_to_monotonic.tv_sec;
 256         vdso_data->wtm_clock_nsec               = tk->wall_to_monotonic.tv_nsec;
 257
 258         if (!use_syscall) {
 259                 /* tkr_mono.cycle_last == tkr_raw.cycle_last */
 260                 vdso_data->cs_cycle_last        = tk->tkr_mono.cycle_last;
 261                 vdso_data->raw_time_sec         = tk->raw_sec;
 262                 vdso_data->raw_time_nsec        = tk->tkr_raw.xtime_nsec;
 263                 vdso_data->xtime_clock_sec      = tk->xtime_sec;
 264                 vdso_data->xtime_clock_snsec    = tk->tkr_mono.xtime_nsec;
 265                 /* tkr_raw.xtime_nsec == 0 */
 266                 vdso_data->cs_mono_mult         = tk->tkr_mono.mult;
 267                 vdso_data->cs_raw_mult          = tk->tkr_raw.mult;
 268                 /* tkr_mono.shift == tkr_raw.shift */
 269                 vdso_data->cs_shift             = tk->tkr_mono.shift;
 270         }
 271
 272         smp_wmb();
 273         ++vdso_data->tb_seq_count;
 274 }
 275
 276 void update_vsyscall_tz(void)
 277 {
 278         vdso_data->tz_minuteswest       = sys_tz.tz_minuteswest;
 279         vdso_data->tz_dsttime           = sys_tz.tz_dsttime;
 280 }