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/page.h> 19 #include <asm/ptdump.h> 20 21 static struct addr_marker address_markers[] = { 22 #ifdef CONFIG_KASAN 23 { KASAN_SHADOW_START, "Kasan shadow start"}, 24 { KASAN_SHADOW_END, "Kasan shadow end"}, 25 #endif 26 { MODULES_VADDR, "Modules" }, 27 { PAGE_OFFSET, "Kernel Mapping" }, 28 { 0, "vmalloc() Area" }, 29 { FDT_FIXED_BASE, "FDT Area" }, 30 { FIXADDR_START, "Fixmap Area" }, 31 { VECTORS_BASE, "Vectors" }, 32 { VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" }, 33 { -1, NULL }, 34 }; 35 36 #define pt_dump_seq_printf(m, fmt, args...) \ 37 ({ \ 38 if (m) \ 39 seq_printf(m, fmt, ##args); \ 40 }) 41 42 #define pt_dump_seq_puts(m, fmt) \ 43 ({ \ 44 if (m) \ 45 seq_printf(m, fmt); \ 46 }) 47 48 struct pg_state { 49 struct seq_file *seq; 50 const struct addr_marker *marker; 51 unsigned long start_address; 52 unsigned level; 53 u64 current_prot; 54 bool check_wx; 55 unsigned long wx_pages; 56 const char *current_domain; 57 }; 58 59 struct prot_bits { 60 u64 mask; 61 u64 val; 62 const char *set; 63 const char *clear; 64 bool ro_bit; 65 bool nx_bit; 66 }; 67 68 static const struct prot_bits pte_bits[] = { 69 { 70 .mask = L_PTE_USER, 71 .val = L_PTE_USER, 72 .set = "USR", 73 .clear = " ", 74 }, { 75 .mask = L_PTE_RDONLY, 76 .val = L_PTE_RDONLY, 77 .set = "ro", 78 .clear = "RW", 79 .ro_bit = true, 80 }, { 81 .mask = L_PTE_XN, 82 .val = L_PTE_XN, 83 .set = "NX", 84 .clear = "x ", 85 .nx_bit = true, 86 }, { 87 .mask = L_PTE_SHARED, 88 .val = L_PTE_SHARED, 89 .set = "SHD", 90 .clear = " ", 91 }, { 92 .mask = L_PTE_MT_MASK, 93 .val = L_PTE_MT_UNCACHED, 94 .set = "SO/UNCACHED", 95 }, { 96 .mask = L_PTE_MT_MASK, 97 .val = L_PTE_MT_BUFFERABLE, 98 .set = "MEM/BUFFERABLE/WC", 99 }, { 100 .mask = L_PTE_MT_MASK, 101 .val = L_PTE_MT_WRITETHROUGH, 102 .set = "MEM/CACHED/WT", 103 }, { 104 .mask = L_PTE_MT_MASK, 105 .val = L_PTE_MT_WRITEBACK, 106 .set = "MEM/CACHED/WBRA", 107 #ifndef CONFIG_ARM_LPAE 108 }, { 109 .mask = L_PTE_MT_MASK, 110 .val = L_PTE_MT_MINICACHE, 111 .set = "MEM/MINICACHE", 112 #endif 113 }, { 114 .mask = L_PTE_MT_MASK, 115 .val = L_PTE_MT_WRITEALLOC, 116 .set = "MEM/CACHED/WBWA", 117 }, { 118 .mask = L_PTE_MT_MASK, 119 .val = L_PTE_MT_DEV_SHARED, 120 .set = "DEV/SHARED", 121 #ifndef CONFIG_ARM_LPAE 122 }, { 123 .mask = L_PTE_MT_MASK, 124 .val = L_PTE_MT_DEV_NONSHARED, 125 .set = "DEV/NONSHARED", 126 #endif 127 }, { 128 .mask = L_PTE_MT_MASK, 129 .val = L_PTE_MT_DEV_WC, 130 .set = "DEV/WC", 131 }, { 132 .mask = L_PTE_MT_MASK, 133 .val = L_PTE_MT_DEV_CACHED, 134 .set = "DEV/CACHED", 135 }, 136 }; 137 138 static const struct prot_bits section_bits[] = { 139 #ifdef CONFIG_ARM_LPAE 140 { 141 .mask = PMD_SECT_USER, 142 .val = PMD_SECT_USER, 143 .set = "USR", 144 }, { 145 .mask = L_PMD_SECT_RDONLY | PMD_SECT_AP2, 146 .val = L_PMD_SECT_RDONLY | PMD_SECT_AP2, 147 .set = "ro", 148 .clear = "RW", 149 .ro_bit = true, 150 #elif __LINUX_ARM_ARCH__ >= 6 151 { 152 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 153 .val = PMD_SECT_APX | PMD_SECT_AP_WRITE, 154 .set = " ro", 155 .ro_bit = true, 156 }, { 157 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 158 .val = PMD_SECT_AP_WRITE, 159 .set = " RW", 160 }, { 161 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 162 .val = PMD_SECT_AP_READ, 163 .set = "USR ro", 164 }, { 165 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 166 .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 167 .set = "USR RW", 168 #else /* ARMv4/ARMv5 */ 169 /* These are approximate */ 170 { 171 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 172 .val = 0, 173 .set = " ro", 174 .ro_bit = true, 175 }, { 176 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 177 .val = PMD_SECT_AP_WRITE, 178 .set = " RW", 179 }, { 180 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 181 .val = PMD_SECT_AP_READ, 182 .set = "USR ro", 183 }, { 184 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 185 .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE, 186 .set = "USR RW", 187 #endif 188 }, { 189 .mask = PMD_SECT_XN, 190 .val = PMD_SECT_XN, 191 .set = "NX", 192 .clear = "x ", 193 .nx_bit = true, 194 }, { 195 .mask = PMD_SECT_S, 196 .val = PMD_SECT_S, 197 .set = "SHD", 198 .clear = " ", 199 }, 200 }; 201 202 struct pg_level { 203 const char *name; 204 const struct prot_bits *bits; 205 size_t num; 206 u64 mask; 207 const struct prot_bits *ro_bit; 208 const struct prot_bits *nx_bit; 209 }; 210 211 static struct pg_level pg_level[] = { 212 { 213 }, { /* pgd */ 214 }, { /* p4d */ 215 }, { /* pud */ 216 }, { /* pmd */ 217 .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD", 218 .bits = section_bits, 219 .num = ARRAY_SIZE(section_bits), 220 }, { /* pte */ 221 .name = "PTE", 222 .bits = pte_bits, 223 .num = ARRAY_SIZE(pte_bits), 224 }, 225 }; 226 227 static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t num) 228 { 229 unsigned i; 230 231 for (i = 0; i < num; i++, bits++) { 232 const char *s; 233 234 if ((st->current_prot & bits->mask) == bits->val) 235 s = bits->set; 236 else 237 s = bits->clear; 238 239 if (s) 240 pt_dump_seq_printf(st->seq, " %s", s); 241 } 242 } 243 244 static void note_prot_wx(struct pg_state *st, unsigned long addr) 245 { 246 if (!st->check_wx) 247 return; 248 if ((st->current_prot & pg_level[st->level].ro_bit->mask) == 249 pg_level[st->level].ro_bit->val) 250 return; 251 if ((st->current_prot & pg_level[st->level].nx_bit->mask) == 252 pg_level[st->level].nx_bit->val) 253 return; 254 255 WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %pS\n", 256 (void *)st->start_address); 257 258 st->wx_pages += (addr - st->start_address) / PAGE_SIZE; 259 } 260 261 static void note_page(struct pg_state *st, unsigned long addr, 262 unsigned int level, u64 val, const char *domain) 263 { 264 static const char units[] = "KMGTPE"; 265 u64 prot = val & pg_level[level].mask; 266 267 if (!st->level) { 268 st->level = level; 269 st->current_prot = prot; 270 st->current_domain = domain; 271 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); 272 } else if (prot != st->current_prot || level != st->level || 273 domain != st->current_domain || 274 addr >= st->marker[1].start_address) { 275 const char *unit = units; 276 unsigned long delta; 277 278 if (st->current_prot) { 279 note_prot_wx(st, addr); 280 pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx ", 281 st->start_address, addr); 282 283 delta = (addr - st->start_address) >> 10; 284 while (!(delta & 1023) && unit[1]) { 285 delta >>= 10; 286 unit++; 287 } 288 pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit, 289 pg_level[st->level].name); 290 if (st->current_domain) 291 pt_dump_seq_printf(st->seq, " %s", 292 st->current_domain); 293 if (pg_level[st->level].bits) 294 dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num); 295 pt_dump_seq_printf(st->seq, "\n"); 296 } 297 298 if (addr >= st->marker[1].start_address) { 299 st->marker++; 300 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", 301 st->marker->name); 302 } 303 st->start_address = addr; 304 st->current_prot = prot; 305 st->current_domain = domain; 306 st->level = level; 307 } 308 } 309 310 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start, 311 const char *domain) 312 { 313 pte_t *pte = pte_offset_kernel(pmd, 0); 314 unsigned long addr; 315 unsigned i; 316 317 for (i = 0; i < PTRS_PER_PTE; i++, pte++) { 318 addr = start + i * PAGE_SIZE; 319 note_page(st, addr, 5, pte_val(*pte), domain); 320 } 321 } 322 323 static const char *get_domain_name(pmd_t *pmd) 324 { 325 #ifndef CONFIG_ARM_LPAE 326 switch (pmd_val(*pmd) & PMD_DOMAIN_MASK) { 327 case PMD_DOMAIN(DOMAIN_KERNEL): 328 return "KERNEL "; 329 case PMD_DOMAIN(DOMAIN_USER): 330 return "USER "; 331 case PMD_DOMAIN(DOMAIN_IO): 332 return "IO "; 333 case PMD_DOMAIN(DOMAIN_VECTORS): 334 return "VECTORS"; 335 default: 336 return "unknown"; 337 } 338 #endif 339 return NULL; 340 } 341 342 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start) 343 { 344 pmd_t *pmd = pmd_offset(pud, 0); 345 unsigned long addr; 346 unsigned i; 347 const char *domain; 348 349 for (i = 0; i < PTRS_PER_PMD; i++, pmd++) { 350 addr = start + i * PMD_SIZE; 351 domain = get_domain_name(pmd); 352 if (pmd_none(*pmd) || pmd_leaf(*pmd) || !pmd_present(*pmd)) 353 note_page(st, addr, 4, pmd_val(*pmd), domain); 354 else 355 walk_pte(st, pmd, addr, domain); 356 357 if (SECTION_SIZE < PMD_SIZE && pmd_leaf(pmd[1])) { 358 addr += SECTION_SIZE; 359 pmd++; 360 domain = get_domain_name(pmd); 361 note_page(st, addr, 4, pmd_val(*pmd), domain); 362 } 363 } 364 } 365 366 static void walk_pud(struct pg_state *st, p4d_t *p4d, unsigned long start) 367 { 368 pud_t *pud = pud_offset(p4d, 0); 369 unsigned long addr; 370 unsigned i; 371 372 for (i = 0; i < PTRS_PER_PUD; i++, pud++) { 373 addr = start + i * PUD_SIZE; 374 if (!pud_none(*pud)) { 375 walk_pmd(st, pud, addr); 376 } else { 377 note_page(st, addr, 3, pud_val(*pud), NULL); 378 } 379 } 380 } 381 382 static void walk_p4d(struct pg_state *st, pgd_t *pgd, unsigned long start) 383 { 384 p4d_t *p4d = p4d_offset(pgd, 0); 385 unsigned long addr; 386 unsigned i; 387 388 for (i = 0; i < PTRS_PER_P4D; i++, p4d++) { 389 addr = start + i * P4D_SIZE; 390 if (!p4d_none(*p4d)) { 391 walk_pud(st, p4d, addr); 392 } else { 393 note_page(st, addr, 2, p4d_val(*p4d), NULL); 394 } 395 } 396 } 397 398 static void walk_pgd(struct pg_state *st, struct mm_struct *mm, 399 unsigned long start) 400 { 401 pgd_t *pgd = pgd_offset(mm, 0UL); 402 unsigned i; 403 unsigned long addr; 404 405 for (i = 0; i < PTRS_PER_PGD; i++, pgd++) { 406 addr = start + i * PGDIR_SIZE; 407 if (!pgd_none(*pgd)) { 408 walk_p4d(st, pgd, addr); 409 } else { 410 note_page(st, addr, 1, pgd_val(*pgd), NULL); 411 } 412 } 413 } 414 415 void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info) 416 { 417 struct pg_state st = { 418 .seq = m, 419 .marker = info->markers, 420 .check_wx = false, 421 }; 422 423 walk_pgd(&st, info->mm, info->base_addr); 424 note_page(&st, 0, 0, 0, NULL); 425 } 426 427 static void __init ptdump_initialize(void) 428 { 429 unsigned i, j; 430 431 for (i = 0; i < ARRAY_SIZE(pg_level); i++) 432 if (pg_level[i].bits) 433 for (j = 0; j < pg_level[i].num; j++) { 434 pg_level[i].mask |= pg_level[i].bits[j].mask; 435 if (pg_level[i].bits[j].ro_bit) 436 pg_level[i].ro_bit = &pg_level[i].bits[j]; 437 if (pg_level[i].bits[j].nx_bit) 438 pg_level[i].nx_bit = &pg_level[i].bits[j]; 439 } 440 #ifdef CONFIG_KASAN 441 address_markers[4].start_address = VMALLOC_START; 442 #else 443 address_markers[2].start_address = VMALLOC_START; 444 #endif 445 } 446 447 static struct ptdump_info kernel_ptdump_info = { 448 .mm = &init_mm, 449 .markers = address_markers, 450 .base_addr = 0, 451 }; 452 453 void ptdump_check_wx(void) 454 { 455 struct pg_state st = { 456 .seq = NULL, 457 .marker = (struct addr_marker[]) { 458 { 0, NULL}, 459 { -1, NULL}, 460 }, 461 .check_wx = true, 462 }; 463 464 walk_pgd(&st, &init_mm, 0); 465 note_page(&st, 0, 0, 0, NULL); 466 if (st.wx_pages) 467 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", 468 st.wx_pages); 469 else 470 pr_info("Checked W+X mappings: passed, no W+X pages found\n"); 471 } 472 473 static int __init ptdump_init(void) 474 { 475 ptdump_initialize(); 476 ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables"); 477 return 0; 478 } 479 __initcall(ptdump_init); 480