1 /* 2 * Debug helper to dump the current kernel pagetables of the system 3 * so that we can see what the various memory ranges are set to. 4 * 5 * (C) Copyright 2008 Intel Corporation 6 * 7 * Author: Arjan van de Ven <arjan@linux.intel.com> 8 * 9 * This program is free software; you can redistribute it and/or 10 * modify it under the terms of the GNU General Public License 11 * as published by the Free Software Foundation; version 2 12 * of the License. 13 */ 14 15 #include <linux/debugfs.h> 16 #include <linux/kasan.h> 17 #include <linux/mm.h> 18 #include <linux/init.h> 19 #include <linux/sched.h> 20 #include <linux/seq_file.h> 21 22 #include <asm/pgtable.h> 23 24 /* 25 * The dumper groups pagetable entries of the same type into one, and for 26 * that it needs to keep some state when walking, and flush this state 27 * when a "break" in the continuity is found. 28 */ 29 struct pg_state { 30 int level; 31 pgprot_t current_prot; 32 unsigned long start_address; 33 unsigned long current_address; 34 const struct addr_marker *marker; 35 unsigned long lines; 36 bool to_dmesg; 37 bool check_wx; 38 unsigned long wx_pages; 39 }; 40 41 struct addr_marker { 42 unsigned long start_address; 43 const char *name; 44 unsigned long max_lines; 45 }; 46 47 /* Address space markers hints */ 48 49 #ifdef CONFIG_X86_64 50 51 enum address_markers_idx { 52 USER_SPACE_NR = 0, 53 KERNEL_SPACE_NR, 54 LOW_KERNEL_NR, 55 VMALLOC_START_NR, 56 VMEMMAP_START_NR, 57 #ifdef CONFIG_KASAN 58 KASAN_SHADOW_START_NR, 59 KASAN_SHADOW_END_NR, 60 #endif 61 CPU_ENTRY_AREA_NR, 62 #ifdef CONFIG_X86_ESPFIX64 63 ESPFIX_START_NR, 64 #endif 65 #ifdef CONFIG_EFI 66 EFI_END_NR, 67 #endif 68 HIGH_KERNEL_NR, 69 MODULES_VADDR_NR, 70 MODULES_END_NR, 71 FIXADDR_START_NR, 72 END_OF_SPACE_NR, 73 }; 74 75 static struct addr_marker address_markers[] = { 76 [USER_SPACE_NR] = { 0, "User Space" }, 77 [KERNEL_SPACE_NR] = { (1UL << 63), "Kernel Space" }, 78 [LOW_KERNEL_NR] = { 0UL, "Low Kernel Mapping" }, 79 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" }, 80 [VMEMMAP_START_NR] = { 0UL, "Vmemmap" }, 81 #ifdef CONFIG_KASAN 82 [KASAN_SHADOW_START_NR] = { KASAN_SHADOW_START, "KASAN shadow" }, 83 [KASAN_SHADOW_END_NR] = { KASAN_SHADOW_END, "KASAN shadow end" }, 84 #endif 85 [CPU_ENTRY_AREA_NR] = { CPU_ENTRY_AREA_BASE,"CPU entry Area" }, 86 #ifdef CONFIG_X86_ESPFIX64 87 [ESPFIX_START_NR] = { ESPFIX_BASE_ADDR, "ESPfix Area", 16 }, 88 #endif 89 #ifdef CONFIG_EFI 90 [EFI_END_NR] = { EFI_VA_END, "EFI Runtime Services" }, 91 #endif 92 [HIGH_KERNEL_NR] = { __START_KERNEL_map, "High Kernel Mapping" }, 93 [MODULES_VADDR_NR] = { MODULES_VADDR, "Modules" }, 94 [MODULES_END_NR] = { MODULES_END, "End Modules" }, 95 [FIXADDR_START_NR] = { FIXADDR_START, "Fixmap Area" }, 96 [END_OF_SPACE_NR] = { -1, NULL } 97 }; 98 99 #else /* CONFIG_X86_64 */ 100 101 enum address_markers_idx { 102 USER_SPACE_NR = 0, 103 KERNEL_SPACE_NR, 104 VMALLOC_START_NR, 105 VMALLOC_END_NR, 106 #ifdef CONFIG_HIGHMEM 107 PKMAP_BASE_NR, 108 #endif 109 CPU_ENTRY_AREA_NR, 110 FIXADDR_START_NR, 111 END_OF_SPACE_NR, 112 }; 113 114 static struct addr_marker address_markers[] = { 115 [USER_SPACE_NR] = { 0, "User Space" }, 116 [KERNEL_SPACE_NR] = { PAGE_OFFSET, "Kernel Mapping" }, 117 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" }, 118 [VMALLOC_END_NR] = { 0UL, "vmalloc() End" }, 119 #ifdef CONFIG_HIGHMEM 120 [PKMAP_BASE_NR] = { 0UL, "Persistent kmap() Area" }, 121 #endif 122 [CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" }, 123 [FIXADDR_START_NR] = { 0UL, "Fixmap area" }, 124 [END_OF_SPACE_NR] = { -1, NULL } 125 }; 126 127 #endif /* !CONFIG_X86_64 */ 128 129 /* Multipliers for offsets within the PTEs */ 130 #define PTE_LEVEL_MULT (PAGE_SIZE) 131 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT) 132 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT) 133 #define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT) 134 #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT) 135 136 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \ 137 ({ \ 138 if (to_dmesg) \ 139 printk(KERN_INFO fmt, ##args); \ 140 else \ 141 if (m) \ 142 seq_printf(m, fmt, ##args); \ 143 }) 144 145 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \ 146 ({ \ 147 if (to_dmesg) \ 148 printk(KERN_CONT fmt, ##args); \ 149 else \ 150 if (m) \ 151 seq_printf(m, fmt, ##args); \ 152 }) 153 154 /* 155 * Print a readable form of a pgprot_t to the seq_file 156 */ 157 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg) 158 { 159 pgprotval_t pr = pgprot_val(prot); 160 static const char * const level_name[] = 161 { "cr3", "pgd", "p4d", "pud", "pmd", "pte" }; 162 163 if (!(pr & _PAGE_PRESENT)) { 164 /* Not present */ 165 pt_dump_cont_printf(m, dmsg, " "); 166 } else { 167 if (pr & _PAGE_USER) 168 pt_dump_cont_printf(m, dmsg, "USR "); 169 else 170 pt_dump_cont_printf(m, dmsg, " "); 171 if (pr & _PAGE_RW) 172 pt_dump_cont_printf(m, dmsg, "RW "); 173 else 174 pt_dump_cont_printf(m, dmsg, "ro "); 175 if (pr & _PAGE_PWT) 176 pt_dump_cont_printf(m, dmsg, "PWT "); 177 else 178 pt_dump_cont_printf(m, dmsg, " "); 179 if (pr & _PAGE_PCD) 180 pt_dump_cont_printf(m, dmsg, "PCD "); 181 else 182 pt_dump_cont_printf(m, dmsg, " "); 183 184 /* Bit 7 has a different meaning on level 3 vs 4 */ 185 if (level <= 4 && pr & _PAGE_PSE) 186 pt_dump_cont_printf(m, dmsg, "PSE "); 187 else 188 pt_dump_cont_printf(m, dmsg, " "); 189 if ((level == 5 && pr & _PAGE_PAT) || 190 ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE)) 191 pt_dump_cont_printf(m, dmsg, "PAT "); 192 else 193 pt_dump_cont_printf(m, dmsg, " "); 194 if (pr & _PAGE_GLOBAL) 195 pt_dump_cont_printf(m, dmsg, "GLB "); 196 else 197 pt_dump_cont_printf(m, dmsg, " "); 198 if (pr & _PAGE_NX) 199 pt_dump_cont_printf(m, dmsg, "NX "); 200 else 201 pt_dump_cont_printf(m, dmsg, "x "); 202 } 203 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]); 204 } 205 206 /* 207 * On 64 bits, sign-extend the 48 bit address to 64 bit 208 */ 209 static unsigned long normalize_addr(unsigned long u) 210 { 211 int shift; 212 if (!IS_ENABLED(CONFIG_X86_64)) 213 return u; 214 215 shift = 64 - (__VIRTUAL_MASK_SHIFT + 1); 216 return (signed long)(u << shift) >> shift; 217 } 218 219 /* 220 * This function gets called on a break in a continuous series 221 * of PTE entries; the next one is different so we need to 222 * print what we collected so far. 223 */ 224 static void note_page(struct seq_file *m, struct pg_state *st, 225 pgprot_t new_prot, int level) 226 { 227 pgprotval_t prot, cur; 228 static const char units[] = "BKMGTPE"; 229 230 /* 231 * If we have a "break" in the series, we need to flush the state that 232 * we have now. "break" is either changing perms, levels or 233 * address space marker. 234 */ 235 prot = pgprot_val(new_prot); 236 cur = pgprot_val(st->current_prot); 237 238 if (!st->level) { 239 /* First entry */ 240 st->current_prot = new_prot; 241 st->level = level; 242 st->marker = address_markers; 243 st->lines = 0; 244 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n", 245 st->marker->name); 246 } else if (prot != cur || level != st->level || 247 st->current_address >= st->marker[1].start_address) { 248 const char *unit = units; 249 unsigned long delta; 250 int width = sizeof(unsigned long) * 2; 251 pgprotval_t pr = pgprot_val(st->current_prot); 252 253 if (st->check_wx && (pr & _PAGE_RW) && !(pr & _PAGE_NX)) { 254 WARN_ONCE(1, 255 "x86/mm: Found insecure W+X mapping at address %p/%pS\n", 256 (void *)st->start_address, 257 (void *)st->start_address); 258 st->wx_pages += (st->current_address - 259 st->start_address) / PAGE_SIZE; 260 } 261 262 /* 263 * Now print the actual finished series 264 */ 265 if (!st->marker->max_lines || 266 st->lines < st->marker->max_lines) { 267 pt_dump_seq_printf(m, st->to_dmesg, 268 "0x%0*lx-0x%0*lx ", 269 width, st->start_address, 270 width, st->current_address); 271 272 delta = st->current_address - st->start_address; 273 while (!(delta & 1023) && unit[1]) { 274 delta >>= 10; 275 unit++; 276 } 277 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ", 278 delta, *unit); 279 printk_prot(m, st->current_prot, st->level, 280 st->to_dmesg); 281 } 282 st->lines++; 283 284 /* 285 * We print markers for special areas of address space, 286 * such as the start of vmalloc space etc. 287 * This helps in the interpretation. 288 */ 289 if (st->current_address >= st->marker[1].start_address) { 290 if (st->marker->max_lines && 291 st->lines > st->marker->max_lines) { 292 unsigned long nskip = 293 st->lines - st->marker->max_lines; 294 pt_dump_seq_printf(m, st->to_dmesg, 295 "... %lu entr%s skipped ... \n", 296 nskip, 297 nskip == 1 ? "y" : "ies"); 298 } 299 st->marker++; 300 st->lines = 0; 301 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n", 302 st->marker->name); 303 } 304 305 st->start_address = st->current_address; 306 st->current_prot = new_prot; 307 st->level = level; 308 } 309 } 310 311 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, unsigned long P) 312 { 313 int i; 314 pte_t *start; 315 pgprotval_t prot; 316 317 start = (pte_t *)pmd_page_vaddr(addr); 318 for (i = 0; i < PTRS_PER_PTE; i++) { 319 prot = pte_flags(*start); 320 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT); 321 note_page(m, st, __pgprot(prot), 5); 322 start++; 323 } 324 } 325 #ifdef CONFIG_KASAN 326 327 /* 328 * This is an optimization for KASAN=y case. Since all kasan page tables 329 * eventually point to the kasan_zero_page we could call note_page() 330 * right away without walking through lower level page tables. This saves 331 * us dozens of seconds (minutes for 5-level config) while checking for 332 * W+X mapping or reading kernel_page_tables debugfs file. 333 */ 334 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st, 335 void *pt) 336 { 337 if (__pa(pt) == __pa(kasan_zero_pmd) || 338 #ifdef CONFIG_X86_5LEVEL 339 __pa(pt) == __pa(kasan_zero_p4d) || 340 #endif 341 __pa(pt) == __pa(kasan_zero_pud)) { 342 pgprotval_t prot = pte_flags(kasan_zero_pte[0]); 343 note_page(m, st, __pgprot(prot), 5); 344 return true; 345 } 346 return false; 347 } 348 #else 349 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st, 350 void *pt) 351 { 352 return false; 353 } 354 #endif 355 356 #if PTRS_PER_PMD > 1 357 358 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, unsigned long P) 359 { 360 int i; 361 pmd_t *start, *pmd_start; 362 pgprotval_t prot; 363 364 pmd_start = start = (pmd_t *)pud_page_vaddr(addr); 365 for (i = 0; i < PTRS_PER_PMD; i++) { 366 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT); 367 if (!pmd_none(*start)) { 368 if (pmd_large(*start) || !pmd_present(*start)) { 369 prot = pmd_flags(*start); 370 note_page(m, st, __pgprot(prot), 4); 371 } else if (!kasan_page_table(m, st, pmd_start)) { 372 walk_pte_level(m, st, *start, 373 P + i * PMD_LEVEL_MULT); 374 } 375 } else 376 note_page(m, st, __pgprot(0), 4); 377 start++; 378 } 379 } 380 381 #else 382 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p) 383 #define pud_large(a) pmd_large(__pmd(pud_val(a))) 384 #define pud_none(a) pmd_none(__pmd(pud_val(a))) 385 #endif 386 387 #if PTRS_PER_PUD > 1 388 389 static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr, unsigned long P) 390 { 391 int i; 392 pud_t *start, *pud_start; 393 pgprotval_t prot; 394 pud_t *prev_pud = NULL; 395 396 pud_start = start = (pud_t *)p4d_page_vaddr(addr); 397 398 for (i = 0; i < PTRS_PER_PUD; i++) { 399 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT); 400 if (!pud_none(*start)) { 401 if (pud_large(*start) || !pud_present(*start)) { 402 prot = pud_flags(*start); 403 note_page(m, st, __pgprot(prot), 3); 404 } else if (!kasan_page_table(m, st, pud_start)) { 405 walk_pmd_level(m, st, *start, 406 P + i * PUD_LEVEL_MULT); 407 } 408 } else 409 note_page(m, st, __pgprot(0), 3); 410 411 prev_pud = start; 412 start++; 413 } 414 } 415 416 #else 417 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(p4d_val(a)),p) 418 #define p4d_large(a) pud_large(__pud(p4d_val(a))) 419 #define p4d_none(a) pud_none(__pud(p4d_val(a))) 420 #endif 421 422 #if PTRS_PER_P4D > 1 423 424 static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, unsigned long P) 425 { 426 int i; 427 p4d_t *start, *p4d_start; 428 pgprotval_t prot; 429 430 p4d_start = start = (p4d_t *)pgd_page_vaddr(addr); 431 432 for (i = 0; i < PTRS_PER_P4D; i++) { 433 st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT); 434 if (!p4d_none(*start)) { 435 if (p4d_large(*start) || !p4d_present(*start)) { 436 prot = p4d_flags(*start); 437 note_page(m, st, __pgprot(prot), 2); 438 } else if (!kasan_page_table(m, st, p4d_start)) { 439 walk_pud_level(m, st, *start, 440 P + i * P4D_LEVEL_MULT); 441 } 442 } else 443 note_page(m, st, __pgprot(0), 2); 444 445 start++; 446 } 447 } 448 449 #else 450 #define walk_p4d_level(m,s,a,p) walk_pud_level(m,s,__p4d(pgd_val(a)),p) 451 #define pgd_large(a) p4d_large(__p4d(pgd_val(a))) 452 #define pgd_none(a) p4d_none(__p4d(pgd_val(a))) 453 #endif 454 455 static inline bool is_hypervisor_range(int idx) 456 { 457 #ifdef CONFIG_X86_64 458 /* 459 * ffff800000000000 - ffff87ffffffffff is reserved for 460 * the hypervisor. 461 */ 462 return (idx >= pgd_index(__PAGE_OFFSET) - 16) && 463 (idx < pgd_index(__PAGE_OFFSET)); 464 #else 465 return false; 466 #endif 467 } 468 469 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd, 470 bool checkwx) 471 { 472 #ifdef CONFIG_X86_64 473 pgd_t *start = (pgd_t *) &init_top_pgt; 474 #else 475 pgd_t *start = swapper_pg_dir; 476 #endif 477 pgprotval_t prot; 478 int i; 479 struct pg_state st = {}; 480 481 if (pgd) { 482 start = pgd; 483 st.to_dmesg = true; 484 } 485 486 st.check_wx = checkwx; 487 if (checkwx) 488 st.wx_pages = 0; 489 490 for (i = 0; i < PTRS_PER_PGD; i++) { 491 st.current_address = normalize_addr(i * PGD_LEVEL_MULT); 492 if (!pgd_none(*start) && !is_hypervisor_range(i)) { 493 if (pgd_large(*start) || !pgd_present(*start)) { 494 prot = pgd_flags(*start); 495 note_page(m, &st, __pgprot(prot), 1); 496 } else { 497 walk_p4d_level(m, &st, *start, 498 i * PGD_LEVEL_MULT); 499 } 500 } else 501 note_page(m, &st, __pgprot(0), 1); 502 503 cond_resched(); 504 start++; 505 } 506 507 /* Flush out the last page */ 508 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT); 509 note_page(m, &st, __pgprot(0), 0); 510 if (!checkwx) 511 return; 512 if (st.wx_pages) 513 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n", 514 st.wx_pages); 515 else 516 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n"); 517 } 518 519 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd) 520 { 521 ptdump_walk_pgd_level_core(m, pgd, false); 522 } 523 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level); 524 525 void ptdump_walk_pgd_level_checkwx(void) 526 { 527 ptdump_walk_pgd_level_core(NULL, NULL, true); 528 } 529 530 static int __init pt_dump_init(void) 531 { 532 /* 533 * Various markers are not compile-time constants, so assign them 534 * here. 535 */ 536 #ifdef CONFIG_X86_64 537 address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET; 538 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START; 539 address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START; 540 #endif 541 #ifdef CONFIG_X86_32 542 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START; 543 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; 544 # ifdef CONFIG_HIGHMEM 545 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE; 546 # endif 547 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START; 548 address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE; 549 #endif 550 return 0; 551 } 552 __initcall(pt_dump_init); 553