arch/arm/mm/dump.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   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 implementation:
   7  * (C) Copyright 2008 Intel Corporation
   8  *
   9  * Author: Arjan van de Ven <arjan@linux.intel.com>
  10  */
  11 #include <linux/debugfs.h>
  12 #include <linux/fs.h>
  13 #include <linux/mm.h>
  14 #include <linux/seq_file.h>
  15
  16 #include <asm/domain.h>
  17 #include <asm/fixmap.h>
  18 #include <asm/memory.h>
  19 #include <asm/pgtable.h>
  20 #include <asm/ptdump.h>
  21
  22 static struct addr_marker address_markers[] = {
  23         { MODULES_VADDR,        "Modules" },
  24         { PAGE_OFFSET,          "Kernel Mapping" },
  25         { 0,                    "vmalloc() Area" },
  26         { VMALLOC_END,          "vmalloc() End" },
  27         { FIXADDR_START,        "Fixmap Area" },
  28         { VECTORS_BASE, "Vectors" },
  29         { VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" },
  30         { -1,                   NULL },
  31 };
  32
  33 #define pt_dump_seq_printf(m, fmt, args...) \
  34 ({                      \
  35         if (m)                                  \
  36                 seq_printf(m, fmt, ##args);     \
  37 })
  38
  39 #define pt_dump_seq_puts(m, fmt)    \
  40 ({                                              \
  41         if (m)                                  \
  42                 seq_printf(m, fmt);     \
  43 })
  44
  45 struct pg_state {
  46         struct seq_file *seq;
  47         const struct addr_marker *marker;
  48         unsigned long start_address;
  49         unsigned level;
  50         u64 current_prot;
  51         bool check_wx;
  52         unsigned long wx_pages;
  53         const char *current_domain;
  54 };
  55
  56 struct prot_bits {
  57         u64             mask;
  58         u64             val;
  59         const char      *set;
  60         const char      *clear;
  61         bool            ro_bit;
  62         bool            nx_bit;
  63 };
  64
  65 static const struct prot_bits pte_bits[] = {
  66         {
  67                 .mask   = L_PTE_USER,
  68                 .val    = L_PTE_USER,
  69                 .set    = "USR",
  70                 .clear  = "   ",
  71         }, {
  72                 .mask   = L_PTE_RDONLY,
  73                 .val    = L_PTE_RDONLY,
  74                 .set    = "ro",
  75                 .clear  = "RW",
  76                 .ro_bit = true,
  77         }, {
  78                 .mask   = L_PTE_XN,
  79                 .val    = L_PTE_XN,
  80                 .set    = "NX",
  81                 .clear  = "x ",
  82                 .nx_bit = true,
  83         }, {
  84                 .mask   = L_PTE_SHARED,
  85                 .val    = L_PTE_SHARED,
  86                 .set    = "SHD",
  87                 .clear  = "   ",
  88         }, {
  89                 .mask   = L_PTE_MT_MASK,
  90                 .val    = L_PTE_MT_UNCACHED,
  91                 .set    = "SO/UNCACHED",
  92         }, {
  93                 .mask   = L_PTE_MT_MASK,
  94                 .val    = L_PTE_MT_BUFFERABLE,
  95                 .set    = "MEM/BUFFERABLE/WC",
  96         }, {
  97                 .mask   = L_PTE_MT_MASK,
  98                 .val    = L_PTE_MT_WRITETHROUGH,
  99                 .set    = "MEM/CACHED/WT",
 100         }, {
 101                 .mask   = L_PTE_MT_MASK,
 102                 .val    = L_PTE_MT_WRITEBACK,
 103                 .set    = "MEM/CACHED/WBRA",
 104 #ifndef CONFIG_ARM_LPAE
 105         }, {
 106                 .mask   = L_PTE_MT_MASK,
 107                 .val    = L_PTE_MT_MINICACHE,
 108                 .set    = "MEM/MINICACHE",
 109 #endif
 110         }, {
 111                 .mask   = L_PTE_MT_MASK,
 112                 .val    = L_PTE_MT_WRITEALLOC,
 113                 .set    = "MEM/CACHED/WBWA",
 114         }, {
 115                 .mask   = L_PTE_MT_MASK,
 116                 .val    = L_PTE_MT_DEV_SHARED,
 117                 .set    = "DEV/SHARED",
 118 #ifndef CONFIG_ARM_LPAE
 119         }, {
 120                 .mask   = L_PTE_MT_MASK,
 121                 .val    = L_PTE_MT_DEV_NONSHARED,
 122                 .set    = "DEV/NONSHARED",
 123 #endif
 124         }, {
 125                 .mask   = L_PTE_MT_MASK,
 126                 .val    = L_PTE_MT_DEV_WC,
 127                 .set    = "DEV/WC",
 128         }, {
 129                 .mask   = L_PTE_MT_MASK,
 130                 .val    = L_PTE_MT_DEV_CACHED,
 131                 .set    = "DEV/CACHED",
 132         },
 133 };
 134
 135 static const struct prot_bits section_bits[] = {
 136 #ifdef CONFIG_ARM_LPAE
 137         {
 138                 .mask   = PMD_SECT_USER,
 139                 .val    = PMD_SECT_USER,
 140                 .set    = "USR",
 141         }, {
 142                 .mask   = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
 143                 .val    = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
 144                 .set    = "ro",
 145                 .clear  = "RW",
 146                 .ro_bit = true,
 147 #elif __LINUX_ARM_ARCH__ >= 6
 148         {
 149                 .mask   = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 150                 .val    = PMD_SECT_APX | PMD_SECT_AP_WRITE,
 151                 .set    = "    ro",
 152                 .ro_bit = true,
 153         }, {
 154                 .mask   = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 155                 .val    = PMD_SECT_AP_WRITE,
 156                 .set    = "    RW",
 157         }, {
 158                 .mask   = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 159                 .val    = PMD_SECT_AP_READ,
 160                 .set    = "USR ro",
 161         }, {
 162                 .mask   = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 163                 .val    = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 164                 .set    = "USR RW",
 165 #else /* ARMv4/ARMv5  */
 166         /* These are approximate */
 167         {
 168                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 169                 .val    = 0,
 170                 .set    = "    ro",
 171                 .ro_bit = true,
 172         }, {
 173                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 174                 .val    = PMD_SECT_AP_WRITE,
 175                 .set    = "    RW",
 176         }, {
 177                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 178                 .val    = PMD_SECT_AP_READ,
 179                 .set    = "USR ro",
 180         }, {
 181                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 182                 .val    = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 183                 .set    = "USR RW",
 184 #endif
 185         }, {
 186                 .mask   = PMD_SECT_XN,
 187                 .val    = PMD_SECT_XN,
 188                 .set    = "NX",
 189                 .clear  = "x ",
 190                 .nx_bit = true,
 191         }, {
 192                 .mask   = PMD_SECT_S,
 193                 .val    = PMD_SECT_S,
 194                 .set    = "SHD",
 195                 .clear  = "   ",
 196         },
 197 };
 198
 199 struct pg_level {
 200         const struct prot_bits *bits;
 201         size_t num;
 202         u64 mask;
 203         const struct prot_bits *ro_bit;
 204         const struct prot_bits *nx_bit;
 205 };
 206
 207 static struct pg_level pg_level[] = {
 208         {
 209         }, { /* pgd */
 210         }, { /* pud */
 211         }, { /* pmd */
 212                 .bits   = section_bits,
 213                 .num    = ARRAY_SIZE(section_bits),
 214         }, { /* pte */
 215                 .bits   = pte_bits,
 216                 .num    = ARRAY_SIZE(pte_bits),
 217         },
 218 };
 219
 220 static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t num)
 221 {
 222         unsigned i;
 223
 224         for (i = 0; i < num; i++, bits++) {
 225                 const char *s;
 226
 227                 if ((st->current_prot & bits->mask) == bits->val)
 228                         s = bits->set;
 229                 else
 230                         s = bits->clear;
 231
 232                 if (s)
 233                         pt_dump_seq_printf(st->seq, " %s", s);
 234         }
 235 }
 236
 237 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 238 {
 239         if (!st->check_wx)
 240                 return;
 241         if ((st->current_prot & pg_level[st->level].ro_bit->mask) ==
 242                                 pg_level[st->level].ro_bit->val)
 243                 return;
 244         if ((st->current_prot & pg_level[st->level].nx_bit->mask) ==
 245                                 pg_level[st->level].nx_bit->val)
 246                 return;
 247
 248         WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %pS\n",
 249                         (void *)st->start_address);
 250
 251         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 252 }
 253
 254 static void note_page(struct pg_state *st, unsigned long addr,
 255                       unsigned int level, u64 val, const char *domain)
 256 {
 257         static const char units[] = "KMGTPE";
 258         u64 prot = val & pg_level[level].mask;
 259
 260         if (!st->level) {
 261                 st->level = level;
 262                 st->current_prot = prot;
 263                 st->current_domain = domain;
 264                 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 265         } else if (prot != st->current_prot || level != st->level ||
 266                    domain != st->current_domain ||
 267                    addr >= st->marker[1].start_address) {
 268                 const char *unit = units;
 269                 unsigned long delta;
 270
 271                 if (st->current_prot) {
 272                         note_prot_wx(st, addr);
 273                         pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx   ",
 274                                    st->start_address, addr);
 275
 276                         delta = (addr - st->start_address) >> 10;
 277                         while (!(delta & 1023) && unit[1]) {
 278                                 delta >>= 10;
 279                                 unit++;
 280                         }
 281                         pt_dump_seq_printf(st->seq, "%9lu%c", delta, *unit);
 282                         if (st->current_domain)
 283                                 pt_dump_seq_printf(st->seq, " %s",
 284                                                         st->current_domain);
 285                         if (pg_level[st->level].bits)
 286                                 dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num);
 287                         pt_dump_seq_printf(st->seq, "\n");
 288                 }
 289
 290                 if (addr >= st->marker[1].start_address) {
 291                         st->marker++;
 292                         pt_dump_seq_printf(st->seq, "---[ %s ]---\n",
 293                                                         st->marker->name);
 294                 }
 295                 st->start_address = addr;
 296                 st->current_prot = prot;
 297                 st->current_domain = domain;
 298                 st->level = level;
 299         }
 300 }
 301
 302 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start,
 303                      const char *domain)
 304 {
 305         pte_t *pte = pte_offset_kernel(pmd, 0);
 306         unsigned long addr;
 307         unsigned i;
 308
 309         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 310                 addr = start + i * PAGE_SIZE;
 311                 note_page(st, addr, 4, pte_val(*pte), domain);
 312         }
 313 }
 314
 315 static const char *get_domain_name(pmd_t *pmd)
 316 {
 317 #ifndef CONFIG_ARM_LPAE
 318         switch (pmd_val(*pmd) & PMD_DOMAIN_MASK) {
 319         case PMD_DOMAIN(DOMAIN_KERNEL):
 320                 return "KERNEL ";
 321         case PMD_DOMAIN(DOMAIN_USER):
 322                 return "USER   ";
 323         case PMD_DOMAIN(DOMAIN_IO):
 324                 return "IO     ";
 325         case PMD_DOMAIN(DOMAIN_VECTORS):
 326                 return "VECTORS";
 327         default:
 328                 return "unknown";
 329         }
 330 #endif
 331         return NULL;
 332 }
 333
 334 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 335 {
 336         pmd_t *pmd = pmd_offset(pud, 0);
 337         unsigned long addr;
 338         unsigned i;
 339         const char *domain;
 340
 341         for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 342                 addr = start + i * PMD_SIZE;
 343                 domain = get_domain_name(pmd);
 344                 if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd))
 345                         note_page(st, addr, 3, pmd_val(*pmd), domain);
 346                 else
 347                         walk_pte(st, pmd, addr, domain);
 348
 349                 if (SECTION_SIZE < PMD_SIZE && pmd_large(pmd[1])) {
 350                         addr += SECTION_SIZE;
 351                         pmd++;
 352                         domain = get_domain_name(pmd);
 353                         note_page(st, addr, 3, pmd_val(*pmd), domain);
 354                 }
 355         }
 356 }
 357
 358 static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
 359 {
 360         pud_t *pud = pud_offset(pgd, 0);
 361         unsigned long addr;
 362         unsigned i;
 363
 364         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 365                 addr = start + i * PUD_SIZE;
 366                 if (!pud_none(*pud)) {
 367                         walk_pmd(st, pud, addr);
 368                 } else {
 369                         note_page(st, addr, 2, pud_val(*pud), NULL);
 370                 }
 371         }
 372 }
 373
 374 static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
 375                         unsigned long start)
 376 {
 377         pgd_t *pgd = pgd_offset(mm, 0UL);
 378         unsigned i;
 379         unsigned long addr;
 380
 381         for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
 382                 addr = start + i * PGDIR_SIZE;
 383                 if (!pgd_none(*pgd)) {
 384                         walk_pud(st, pgd, addr);
 385                 } else {
 386                         note_page(st, addr, 1, pgd_val(*pgd), NULL);
 387                 }
 388         }
 389 }
 390
 391 void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
 392 {
 393         struct pg_state st = {
 394                 .seq = m,
 395                 .marker = info->markers,
 396                 .check_wx = false,
 397         };
 398
 399         walk_pgd(&st, info->mm, info->base_addr);
 400         note_page(&st, 0, 0, 0, NULL);
 401 }
 402
 403 static void ptdump_initialize(void)
 404 {
 405         unsigned i, j;
 406
 407         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 408                 if (pg_level[i].bits)
 409                         for (j = 0; j < pg_level[i].num; j++) {
 410                                 pg_level[i].mask |= pg_level[i].bits[j].mask;
 411                                 if (pg_level[i].bits[j].ro_bit)
 412                                         pg_level[i].ro_bit = &pg_level[i].bits[j];
 413                                 if (pg_level[i].bits[j].nx_bit)
 414                                         pg_level[i].nx_bit = &pg_level[i].bits[j];
 415                         }
 416
 417         address_markers[2].start_address = VMALLOC_START;
 418 }
 419
 420 static struct ptdump_info kernel_ptdump_info = {
 421         .mm = &init_mm,
 422         .markers = address_markers,
 423         .base_addr = 0,
 424 };
 425
 426 void ptdump_check_wx(void)
 427 {
 428         struct pg_state st = {
 429                 .seq = NULL,
 430                 .marker = (struct addr_marker[]) {
 431                         { 0, NULL},
 432                         { -1, NULL},
 433                 },
 434                 .check_wx = true,
 435         };
 436
 437         walk_pgd(&st, &init_mm, 0);
 438         note_page(&st, 0, 0, 0, NULL);
 439         if (st.wx_pages)
 440                 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n",
 441                         st.wx_pages);
 442         else
 443                 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
 444 }
 445
 446 static int ptdump_init(void)
 447 {
 448         ptdump_initialize();
 449         ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
 450         return 0;
 451 }
 452 __initcall(ptdump_init);