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