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