arch/arm64/mm/dump.c

   1 /*
   2  * Copyright (c) 2014, The Linux Foundation. All rights reserved.
   3  * Debug helper to dump the current kernel pagetables of the system
   4  * so that we can see what the various memory ranges are set to.
   5  *
   6  * Derived from x86 and arm implementation:
   7  * (C) Copyright 2008 Intel Corporation
   8  *
   9  * Author: Arjan van de Ven <arjan@linux.intel.com>
  10  *
  11  * This program is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU General Public License
  13  * as published by the Free Software Foundation; version 2
  14  * of the License.
  15  */
  16 #include <linux/debugfs.h>
  17 #include <linux/errno.h>
  18 #include <linux/fs.h>
  19 #include <linux/io.h>
  20 #include <linux/init.h>
  21 #include <linux/mm.h>
  22 #include <linux/sched.h>
  23 #include <linux/seq_file.h>
  24
  25 #include <asm/fixmap.h>
  26 #include <asm/kasan.h>
  27 #include <asm/memory.h>
  28 #include <asm/pgtable.h>
  29 #include <asm/pgtable-hwdef.h>
  30 #include <asm/ptdump.h>
  31
  32 static const struct addr_marker address_markers[] = {
  33 #ifdef CONFIG_KASAN
  34         { KASAN_SHADOW_START,           "Kasan shadow start" },
  35         { KASAN_SHADOW_END,             "Kasan shadow end" },
  36 #endif
  37         { MODULES_VADDR,                "Modules start" },
  38         { MODULES_END,                  "Modules end" },
  39         { VMALLOC_START,                "vmalloc() area" },
  40         { VMALLOC_END,                  "vmalloc() end" },
  41         { FIXADDR_START,                "Fixmap start" },
  42         { FIXADDR_TOP,                  "Fixmap end" },
  43         { PCI_IO_START,                 "PCI I/O start" },
  44         { PCI_IO_END,                   "PCI I/O end" },
  45 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  46         { VMEMMAP_START,                "vmemmap start" },
  47         { VMEMMAP_START + VMEMMAP_SIZE, "vmemmap end" },
  48 #endif
  49         { PAGE_OFFSET,                  "Linear mapping" },
  50         { -1,                           NULL },
  51 };
  52
  53 #define pt_dump_seq_printf(m, fmt, args...)     \
  54 ({                                              \
  55         if (m)                                  \
  56                 seq_printf(m, fmt, ##args);     \
  57 })
  58
  59 #define pt_dump_seq_puts(m, fmt)        \
  60 ({                                      \
  61         if (m)                          \
  62                 seq_printf(m, fmt);     \
  63 })
  64
  65 /*
  66  * The page dumper groups page table entries of the same type into a single
  67  * description. It uses pg_state to track the range information while
  68  * iterating over the pte entries. When the continuity is broken it then
  69  * dumps out a description of the range.
  70  */
  71 struct pg_state {
  72         struct seq_file *seq;
  73         const struct addr_marker *marker;
  74         unsigned long start_address;
  75         unsigned level;
  76         u64 current_prot;
  77         bool check_wx;
  78         unsigned long wx_pages;
  79         unsigned long uxn_pages;
  80 };
  81
  82 struct prot_bits {
  83         u64             mask;
  84         u64             val;
  85         const char      *set;
  86         const char      *clear;
  87 };
  88
  89 static const struct prot_bits pte_bits[] = {
  90         {
  91                 .mask   = PTE_VALID,
  92                 .val    = PTE_VALID,
  93                 .set    = " ",
  94                 .clear  = "F",
  95         }, {
  96                 .mask   = PTE_USER,
  97                 .val    = PTE_USER,
  98                 .set    = "USR",
  99                 .clear  = "   ",
 100         }, {
 101                 .mask   = PTE_RDONLY,
 102                 .val    = PTE_RDONLY,
 103                 .set    = "ro",
 104                 .clear  = "RW",
 105         }, {
 106                 .mask   = PTE_PXN,
 107                 .val    = PTE_PXN,
 108                 .set    = "NX",
 109                 .clear  = "x ",
 110         }, {
 111                 .mask   = PTE_SHARED,
 112                 .val    = PTE_SHARED,
 113                 .set    = "SHD",
 114                 .clear  = "   ",
 115         }, {
 116                 .mask   = PTE_AF,
 117                 .val    = PTE_AF,
 118                 .set    = "AF",
 119                 .clear  = "  ",
 120         }, {
 121                 .mask   = PTE_NG,
 122                 .val    = PTE_NG,
 123                 .set    = "NG",
 124                 .clear  = "  ",
 125         }, {
 126                 .mask   = PTE_CONT,
 127                 .val    = PTE_CONT,
 128                 .set    = "CON",
 129                 .clear  = "   ",
 130         }, {
 131                 .mask   = PTE_TABLE_BIT,
 132                 .val    = PTE_TABLE_BIT,
 133                 .set    = "   ",
 134                 .clear  = "BLK",
 135         }, {
 136                 .mask   = PTE_UXN,
 137                 .val    = PTE_UXN,
 138                 .set    = "UXN",
 139         }, {
 140                 .mask   = PTE_ATTRINDX_MASK,
 141                 .val    = PTE_ATTRINDX(MT_DEVICE_nGnRnE),
 142                 .set    = "DEVICE/nGnRnE",
 143         }, {
 144                 .mask   = PTE_ATTRINDX_MASK,
 145                 .val    = PTE_ATTRINDX(MT_DEVICE_nGnRE),
 146                 .set    = "DEVICE/nGnRE",
 147         }, {
 148                 .mask   = PTE_ATTRINDX_MASK,
 149                 .val    = PTE_ATTRINDX(MT_DEVICE_GRE),
 150                 .set    = "DEVICE/GRE",
 151         }, {
 152                 .mask   = PTE_ATTRINDX_MASK,
 153                 .val    = PTE_ATTRINDX(MT_NORMAL_NC),
 154                 .set    = "MEM/NORMAL-NC",
 155         }, {
 156                 .mask   = PTE_ATTRINDX_MASK,
 157                 .val    = PTE_ATTRINDX(MT_NORMAL),
 158                 .set    = "MEM/NORMAL",
 159         }
 160 };
 161
 162 struct pg_level {
 163         const struct prot_bits *bits;
 164         const char *name;
 165         size_t num;
 166         u64 mask;
 167 };
 168
 169 static struct pg_level pg_level[] = {
 170         {
 171         }, { /* pgd */
 172                 .name   = "PGD",
 173                 .bits   = pte_bits,
 174                 .num    = ARRAY_SIZE(pte_bits),
 175         }, { /* pud */
 176                 .name   = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
 177                 .bits   = pte_bits,
 178                 .num    = ARRAY_SIZE(pte_bits),
 179         }, { /* pmd */
 180                 .name   = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD",
 181                 .bits   = pte_bits,
 182                 .num    = ARRAY_SIZE(pte_bits),
 183         }, { /* pte */
 184                 .name   = "PTE",
 185                 .bits   = pte_bits,
 186                 .num    = ARRAY_SIZE(pte_bits),
 187         },
 188 };
 189
 190 static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
 191                         size_t num)
 192 {
 193         unsigned i;
 194
 195         for (i = 0; i < num; i++, bits++) {
 196                 const char *s;
 197
 198                 if ((st->current_prot & bits->mask) == bits->val)
 199                         s = bits->set;
 200                 else
 201                         s = bits->clear;
 202
 203                 if (s)
 204                         pt_dump_seq_printf(st->seq, " %s", s);
 205         }
 206 }
 207
 208 static void note_prot_uxn(struct pg_state *st, unsigned long addr)
 209 {
 210         if (!st->check_wx)
 211                 return;
 212
 213         if ((st->current_prot & PTE_UXN) == PTE_UXN)
 214                 return;
 215
 216         WARN_ONCE(1, "arm64/mm: Found non-UXN mapping at address %p/%pS\n",
 217                   (void *)st->start_address, (void *)st->start_address);
 218
 219         st->uxn_pages += (addr - st->start_address) / PAGE_SIZE;
 220 }
 221
 222 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 223 {
 224         if (!st->check_wx)
 225                 return;
 226         if ((st->current_prot & PTE_RDONLY) == PTE_RDONLY)
 227                 return;
 228         if ((st->current_prot & PTE_PXN) == PTE_PXN)
 229                 return;
 230
 231         WARN_ONCE(1, "arm64/mm: Found insecure W+X mapping at address %p/%pS\n",
 232                   (void *)st->start_address, (void *)st->start_address);
 233
 234         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 235 }
 236
 237 static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
 238                                 u64 val)
 239 {
 240         static const char units[] = "KMGTPE";
 241         u64 prot = val & pg_level[level].mask;
 242
 243         if (!st->level) {
 244                 st->level = level;
 245                 st->current_prot = prot;
 246                 st->start_address = addr;
 247                 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 248         } else if (prot != st->current_prot || level != st->level ||
 249                    addr >= st->marker[1].start_address) {
 250                 const char *unit = units;
 251                 unsigned long delta;
 252
 253                 if (st->current_prot) {
 254                         note_prot_uxn(st, addr);
 255                         note_prot_wx(st, addr);
 256                         pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx   ",
 257                                    st->start_address, addr);
 258
 259                         delta = (addr - st->start_address) >> 10;
 260                         while (!(delta & 1023) && unit[1]) {
 261                                 delta >>= 10;
 262                                 unit++;
 263                         }
 264                         pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
 265                                    pg_level[st->level].name);
 266                         if (pg_level[st->level].bits)
 267                                 dump_prot(st, pg_level[st->level].bits,
 268                                           pg_level[st->level].num);
 269                         pt_dump_seq_puts(st->seq, "\n");
 270                 }
 271
 272                 if (addr >= st->marker[1].start_address) {
 273                         st->marker++;
 274                         pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 275                 }
 276
 277                 st->start_address = addr;
 278                 st->current_prot = prot;
 279                 st->level = level;
 280         }
 281
 282         if (addr >= st->marker[1].start_address) {
 283                 st->marker++;
 284                 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 285         }
 286
 287 }
 288
 289 static void walk_pte(struct pg_state *st, pmd_t *pmdp, unsigned long start,
 290                      unsigned long end)
 291 {
 292         unsigned long addr = start;
 293         pte_t *ptep = pte_offset_kernel(pmdp, start);
 294
 295         do {
 296                 note_page(st, addr, 4, READ_ONCE(pte_val(*ptep)));
 297         } while (ptep++, addr += PAGE_SIZE, addr != end);
 298 }
 299
 300 static void walk_pmd(struct pg_state *st, pud_t *pudp, unsigned long start,
 301                      unsigned long end)
 302 {
 303         unsigned long next, addr = start;
 304         pmd_t *pmdp = pmd_offset(pudp, start);
 305
 306         do {
 307                 pmd_t pmd = READ_ONCE(*pmdp);
 308                 next = pmd_addr_end(addr, end);
 309
 310                 if (pmd_none(pmd) || pmd_sect(pmd)) {
 311                         note_page(st, addr, 3, pmd_val(pmd));
 312                 } else {
 313                         BUG_ON(pmd_bad(pmd));
 314                         walk_pte(st, pmdp, addr, next);
 315                 }
 316         } while (pmdp++, addr = next, addr != end);
 317 }
 318
 319 static void walk_pud(struct pg_state *st, pgd_t *pgdp, unsigned long start,
 320                      unsigned long end)
 321 {
 322         unsigned long next, addr = start;
 323         pud_t *pudp = pud_offset(pgdp, start);
 324
 325         do {
 326                 pud_t pud = READ_ONCE(*pudp);
 327                 next = pud_addr_end(addr, end);
 328
 329                 if (pud_none(pud) || pud_sect(pud)) {
 330                         note_page(st, addr, 2, pud_val(pud));
 331                 } else {
 332                         BUG_ON(pud_bad(pud));
 333                         walk_pmd(st, pudp, addr, next);
 334                 }
 335         } while (pudp++, addr = next, addr != end);
 336 }
 337
 338 static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
 339                      unsigned long start)
 340 {
 341         unsigned long end = (start < TASK_SIZE_64) ? TASK_SIZE_64 : 0;
 342         unsigned long next, addr = start;
 343         pgd_t *pgdp = pgd_offset(mm, start);
 344
 345         do {
 346                 pgd_t pgd = READ_ONCE(*pgdp);
 347                 next = pgd_addr_end(addr, end);
 348
 349                 if (pgd_none(pgd)) {
 350                         note_page(st, addr, 1, pgd_val(pgd));
 351                 } else {
 352                         BUG_ON(pgd_bad(pgd));
 353                         walk_pud(st, pgdp, addr, next);
 354                 }
 355         } while (pgdp++, addr = next, addr != end);
 356 }
 357
 358 void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
 359 {
 360         struct pg_state st = {
 361                 .seq = m,
 362                 .marker = info->markers,
 363         };
 364
 365         walk_pgd(&st, info->mm, info->base_addr);
 366
 367         note_page(&st, 0, 0, 0);
 368 }
 369
 370 static void ptdump_initialize(void)
 371 {
 372         unsigned i, j;
 373
 374         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 375                 if (pg_level[i].bits)
 376                         for (j = 0; j < pg_level[i].num; j++)
 377                                 pg_level[i].mask |= pg_level[i].bits[j].mask;
 378 }
 379
 380 static struct ptdump_info kernel_ptdump_info = {
 381         .mm             = &init_mm,
 382         .markers        = address_markers,
 383         .base_addr      = VA_START,
 384 };
 385
 386 void ptdump_check_wx(void)
 387 {
 388         struct pg_state st = {
 389                 .seq = NULL,
 390                 .marker = (struct addr_marker[]) {
 391                         { 0, NULL},
 392                         { -1, NULL},
 393                 },
 394                 .check_wx = true,
 395         };
 396
 397         walk_pgd(&st, &init_mm, VA_START);
 398         note_page(&st, 0, 0, 0);
 399         if (st.wx_pages || st.uxn_pages)
 400                 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\n",
 401                         st.wx_pages, st.uxn_pages);
 402         else
 403                 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
 404 }
 405
 406 static int ptdump_init(void)
 407 {
 408         ptdump_initialize();
 409         return ptdump_debugfs_register(&kernel_ptdump_info,
 410                                         "kernel_page_tables");
 411 }
 412 device_initcall(ptdump_init);