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/mm.h> 17 #include <linux/module.h> 18 #include <linux/seq_file.h> 19 20 #include <asm/pgtable.h> 21 22 /* 23 * The dumper groups pagetable entries of the same type into one, and for 24 * that it needs to keep some state when walking, and flush this state 25 * when a "break" in the continuity is found. 26 */ 27 struct pg_state { 28 int level; 29 pgprot_t current_prot; 30 unsigned long start_address; 31 unsigned long current_address; 32 const struct addr_marker *marker; 33 unsigned long lines; 34 bool to_dmesg; 35 }; 36 37 struct addr_marker { 38 unsigned long start_address; 39 const char *name; 40 unsigned long max_lines; 41 }; 42 43 /* indices for address_markers; keep sync'd w/ address_markers below */ 44 enum address_markers_idx { 45 USER_SPACE_NR = 0, 46 #ifdef CONFIG_X86_64 47 KERNEL_SPACE_NR, 48 LOW_KERNEL_NR, 49 VMALLOC_START_NR, 50 VMEMMAP_START_NR, 51 # ifdef CONFIG_X86_ESPFIX64 52 ESPFIX_START_NR, 53 # endif 54 HIGH_KERNEL_NR, 55 MODULES_VADDR_NR, 56 MODULES_END_NR, 57 #else 58 KERNEL_SPACE_NR, 59 VMALLOC_START_NR, 60 VMALLOC_END_NR, 61 # ifdef CONFIG_HIGHMEM 62 PKMAP_BASE_NR, 63 # endif 64 FIXADDR_START_NR, 65 #endif 66 }; 67 68 /* Address space markers hints */ 69 static struct addr_marker address_markers[] = { 70 { 0, "User Space" }, 71 #ifdef CONFIG_X86_64 72 { 0x8000000000000000UL, "Kernel Space" }, 73 { PAGE_OFFSET, "Low Kernel Mapping" }, 74 { VMALLOC_START, "vmalloc() Area" }, 75 { VMEMMAP_START, "Vmemmap" }, 76 # ifdef CONFIG_X86_ESPFIX64 77 { ESPFIX_BASE_ADDR, "ESPfix Area", 16 }, 78 # endif 79 # ifdef CONFIG_EFI 80 { EFI_VA_END, "EFI Runtime Services" }, 81 # endif 82 { __START_KERNEL_map, "High Kernel Mapping" }, 83 { MODULES_VADDR, "Modules" }, 84 { MODULES_END, "End Modules" }, 85 #else 86 { PAGE_OFFSET, "Kernel Mapping" }, 87 { 0/* VMALLOC_START */, "vmalloc() Area" }, 88 { 0/*VMALLOC_END*/, "vmalloc() End" }, 89 # ifdef CONFIG_HIGHMEM 90 { 0/*PKMAP_BASE*/, "Persisent kmap() Area" }, 91 # endif 92 { 0/*FIXADDR_START*/, "Fixmap Area" }, 93 #endif 94 { -1, NULL } /* End of list */ 95 }; 96 97 /* Multipliers for offsets within the PTEs */ 98 #define PTE_LEVEL_MULT (PAGE_SIZE) 99 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT) 100 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT) 101 #define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT) 102 103 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \ 104 ({ \ 105 if (to_dmesg) \ 106 printk(KERN_INFO fmt, ##args); \ 107 else \ 108 if (m) \ 109 seq_printf(m, fmt, ##args); \ 110 }) 111 112 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \ 113 ({ \ 114 if (to_dmesg) \ 115 printk(KERN_CONT fmt, ##args); \ 116 else \ 117 if (m) \ 118 seq_printf(m, fmt, ##args); \ 119 }) 120 121 /* 122 * Print a readable form of a pgprot_t to the seq_file 123 */ 124 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg) 125 { 126 pgprotval_t pr = pgprot_val(prot); 127 static const char * const level_name[] = 128 { "cr3", "pgd", "pud", "pmd", "pte" }; 129 130 if (!pgprot_val(prot)) { 131 /* Not present */ 132 pt_dump_cont_printf(m, dmsg, " "); 133 } else { 134 if (pr & _PAGE_USER) 135 pt_dump_cont_printf(m, dmsg, "USR "); 136 else 137 pt_dump_cont_printf(m, dmsg, " "); 138 if (pr & _PAGE_RW) 139 pt_dump_cont_printf(m, dmsg, "RW "); 140 else 141 pt_dump_cont_printf(m, dmsg, "ro "); 142 if (pr & _PAGE_PWT) 143 pt_dump_cont_printf(m, dmsg, "PWT "); 144 else 145 pt_dump_cont_printf(m, dmsg, " "); 146 if (pr & _PAGE_PCD) 147 pt_dump_cont_printf(m, dmsg, "PCD "); 148 else 149 pt_dump_cont_printf(m, dmsg, " "); 150 151 /* Bit 7 has a different meaning on level 3 vs 4 */ 152 if (level <= 3 && pr & _PAGE_PSE) 153 pt_dump_cont_printf(m, dmsg, "PSE "); 154 else 155 pt_dump_cont_printf(m, dmsg, " "); 156 if ((level == 4 && pr & _PAGE_PAT) || 157 ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE)) 158 pt_dump_cont_printf(m, dmsg, "PAT "); 159 else 160 pt_dump_cont_printf(m, dmsg, " "); 161 if (pr & _PAGE_GLOBAL) 162 pt_dump_cont_printf(m, dmsg, "GLB "); 163 else 164 pt_dump_cont_printf(m, dmsg, " "); 165 if (pr & _PAGE_NX) 166 pt_dump_cont_printf(m, dmsg, "NX "); 167 else 168 pt_dump_cont_printf(m, dmsg, "x "); 169 } 170 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]); 171 } 172 173 /* 174 * On 64 bits, sign-extend the 48 bit address to 64 bit 175 */ 176 static unsigned long normalize_addr(unsigned long u) 177 { 178 #ifdef CONFIG_X86_64 179 return (signed long)(u << 16) >> 16; 180 #else 181 return u; 182 #endif 183 } 184 185 /* 186 * This function gets called on a break in a continuous series 187 * of PTE entries; the next one is different so we need to 188 * print what we collected so far. 189 */ 190 static void note_page(struct seq_file *m, struct pg_state *st, 191 pgprot_t new_prot, int level) 192 { 193 pgprotval_t prot, cur; 194 static const char units[] = "BKMGTPE"; 195 196 /* 197 * If we have a "break" in the series, we need to flush the state that 198 * we have now. "break" is either changing perms, levels or 199 * address space marker. 200 */ 201 prot = pgprot_val(new_prot); 202 cur = pgprot_val(st->current_prot); 203 204 if (!st->level) { 205 /* First entry */ 206 st->current_prot = new_prot; 207 st->level = level; 208 st->marker = address_markers; 209 st->lines = 0; 210 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n", 211 st->marker->name); 212 } else if (prot != cur || level != st->level || 213 st->current_address >= st->marker[1].start_address) { 214 const char *unit = units; 215 unsigned long delta; 216 int width = sizeof(unsigned long) * 2; 217 218 /* 219 * Now print the actual finished series 220 */ 221 if (!st->marker->max_lines || 222 st->lines < st->marker->max_lines) { 223 pt_dump_seq_printf(m, st->to_dmesg, 224 "0x%0*lx-0x%0*lx ", 225 width, st->start_address, 226 width, st->current_address); 227 228 delta = st->current_address - st->start_address; 229 while (!(delta & 1023) && unit[1]) { 230 delta >>= 10; 231 unit++; 232 } 233 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ", 234 delta, *unit); 235 printk_prot(m, st->current_prot, st->level, 236 st->to_dmesg); 237 } 238 st->lines++; 239 240 /* 241 * We print markers for special areas of address space, 242 * such as the start of vmalloc space etc. 243 * This helps in the interpretation. 244 */ 245 if (st->current_address >= st->marker[1].start_address) { 246 if (st->marker->max_lines && 247 st->lines > st->marker->max_lines) { 248 unsigned long nskip = 249 st->lines - st->marker->max_lines; 250 pt_dump_seq_printf(m, st->to_dmesg, 251 "... %lu entr%s skipped ... \n", 252 nskip, 253 nskip == 1 ? "y" : "ies"); 254 } 255 st->marker++; 256 st->lines = 0; 257 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n", 258 st->marker->name); 259 } 260 261 st->start_address = st->current_address; 262 st->current_prot = new_prot; 263 st->level = level; 264 } 265 } 266 267 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, 268 unsigned long P) 269 { 270 int i; 271 pte_t *start; 272 pgprotval_t prot; 273 274 start = (pte_t *) pmd_page_vaddr(addr); 275 for (i = 0; i < PTRS_PER_PTE; i++) { 276 prot = pte_flags(*start); 277 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT); 278 note_page(m, st, __pgprot(prot), 4); 279 start++; 280 } 281 } 282 283 #if PTRS_PER_PMD > 1 284 285 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, 286 unsigned long P) 287 { 288 int i; 289 pmd_t *start; 290 pgprotval_t prot; 291 292 start = (pmd_t *) pud_page_vaddr(addr); 293 for (i = 0; i < PTRS_PER_PMD; i++) { 294 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT); 295 if (!pmd_none(*start)) { 296 if (pmd_large(*start) || !pmd_present(*start)) { 297 prot = pmd_flags(*start); 298 note_page(m, st, __pgprot(prot), 3); 299 } else { 300 walk_pte_level(m, st, *start, 301 P + i * PMD_LEVEL_MULT); 302 } 303 } else 304 note_page(m, st, __pgprot(0), 3); 305 start++; 306 } 307 } 308 309 #else 310 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p) 311 #define pud_large(a) pmd_large(__pmd(pud_val(a))) 312 #define pud_none(a) pmd_none(__pmd(pud_val(a))) 313 #endif 314 315 #if PTRS_PER_PUD > 1 316 317 static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr, 318 unsigned long P) 319 { 320 int i; 321 pud_t *start; 322 pgprotval_t prot; 323 324 start = (pud_t *) pgd_page_vaddr(addr); 325 326 for (i = 0; i < PTRS_PER_PUD; i++) { 327 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT); 328 if (!pud_none(*start)) { 329 if (pud_large(*start) || !pud_present(*start)) { 330 prot = pud_flags(*start); 331 note_page(m, st, __pgprot(prot), 2); 332 } else { 333 walk_pmd_level(m, st, *start, 334 P + i * PUD_LEVEL_MULT); 335 } 336 } else 337 note_page(m, st, __pgprot(0), 2); 338 339 start++; 340 } 341 } 342 343 #else 344 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p) 345 #define pgd_large(a) pud_large(__pud(pgd_val(a))) 346 #define pgd_none(a) pud_none(__pud(pgd_val(a))) 347 #endif 348 349 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd) 350 { 351 #ifdef CONFIG_X86_64 352 pgd_t *start = (pgd_t *) &init_level4_pgt; 353 #else 354 pgd_t *start = swapper_pg_dir; 355 #endif 356 pgprotval_t prot; 357 int i; 358 struct pg_state st = {}; 359 360 if (pgd) { 361 start = pgd; 362 st.to_dmesg = true; 363 } 364 365 for (i = 0; i < PTRS_PER_PGD; i++) { 366 st.current_address = normalize_addr(i * PGD_LEVEL_MULT); 367 if (!pgd_none(*start)) { 368 if (pgd_large(*start) || !pgd_present(*start)) { 369 prot = pgd_flags(*start); 370 note_page(m, &st, __pgprot(prot), 1); 371 } else { 372 walk_pud_level(m, &st, *start, 373 i * PGD_LEVEL_MULT); 374 } 375 } else 376 note_page(m, &st, __pgprot(0), 1); 377 378 start++; 379 } 380 381 /* Flush out the last page */ 382 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT); 383 note_page(m, &st, __pgprot(0), 0); 384 } 385 386 static int ptdump_show(struct seq_file *m, void *v) 387 { 388 ptdump_walk_pgd_level(m, NULL); 389 return 0; 390 } 391 392 static int ptdump_open(struct inode *inode, struct file *filp) 393 { 394 return single_open(filp, ptdump_show, NULL); 395 } 396 397 static const struct file_operations ptdump_fops = { 398 .open = ptdump_open, 399 .read = seq_read, 400 .llseek = seq_lseek, 401 .release = single_release, 402 }; 403 404 static int pt_dump_init(void) 405 { 406 struct dentry *pe; 407 408 #ifdef CONFIG_X86_32 409 /* Not a compile-time constant on x86-32 */ 410 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START; 411 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END; 412 # ifdef CONFIG_HIGHMEM 413 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE; 414 # endif 415 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START; 416 #endif 417 418 pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL, 419 &ptdump_fops); 420 if (!pe) 421 return -ENOMEM; 422 423 return 0; 424 } 425 426 __initcall(pt_dump_init); 427 MODULE_LICENSE("GPL"); 428 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>"); 429 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables"); 430