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 return ptdump_debugfs_register(&kernel_ptdump_info, 450 "kernel_page_tables"); 451 } 452 __initcall(ptdump_init); 453