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