arch/x86/mm/dump_pagetables.c

   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) & PTE_FLAGS_MASK;
 202         cur = pgprot_val(st->current_prot) & PTE_FLAGS_MASK;
 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
 273         start = (pte_t *) pmd_page_vaddr(addr);
 274         for (i = 0; i < PTRS_PER_PTE; i++) {
 275                 pgprot_t prot = pte_pgprot(*start);
 276
 277                 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
 278                 note_page(m, st, 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
 291         start = (pmd_t *) pud_page_vaddr(addr);
 292         for (i = 0; i < PTRS_PER_PMD; i++) {
 293                 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
 294                 if (!pmd_none(*start)) {
 295                         pgprotval_t prot = pmd_val(*start) & PTE_FLAGS_MASK;
 296
 297                         if (pmd_large(*start) || !pmd_present(*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                 } else
 303                         note_page(m, st, __pgprot(0), 3);
 304                 start++;
 305         }
 306 }
 307
 308 #else
 309 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
 310 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
 311 #define pud_none(a)  pmd_none(__pmd(pud_val(a)))
 312 #endif
 313
 314 #if PTRS_PER_PUD > 1
 315
 316 static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
 317                                                         unsigned long P)
 318 {
 319         int i;
 320         pud_t *start;
 321
 322         start = (pud_t *) pgd_page_vaddr(addr);
 323
 324         for (i = 0; i < PTRS_PER_PUD; i++) {
 325                 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
 326                 if (!pud_none(*start)) {
 327                         pgprotval_t prot = pud_val(*start) & PTE_FLAGS_MASK;
 328
 329                         if (pud_large(*start) || !pud_present(*start))
 330                                 note_page(m, st, __pgprot(prot), 2);
 331                         else
 332                                 walk_pmd_level(m, st, *start,
 333                                                P + i * PUD_LEVEL_MULT);
 334                 } else
 335                         note_page(m, st, __pgprot(0), 2);
 336
 337                 start++;
 338         }
 339 }
 340
 341 #else
 342 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p)
 343 #define pgd_large(a) pud_large(__pud(pgd_val(a)))
 344 #define pgd_none(a)  pud_none(__pud(pgd_val(a)))
 345 #endif
 346
 347 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
 348 {
 349 #ifdef CONFIG_X86_64
 350         pgd_t *start = (pgd_t *) &init_level4_pgt;
 351 #else
 352         pgd_t *start = swapper_pg_dir;
 353 #endif
 354         int i;
 355         struct pg_state st = {};
 356
 357         if (pgd) {
 358                 start = pgd;
 359                 st.to_dmesg = true;
 360         }
 361
 362         for (i = 0; i < PTRS_PER_PGD; i++) {
 363                 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
 364                 if (!pgd_none(*start)) {
 365                         pgprotval_t prot = pgd_val(*start) & PTE_FLAGS_MASK;
 366
 367                         if (pgd_large(*start) || !pgd_present(*start))
 368                                 note_page(m, &st, __pgprot(prot), 1);
 369                         else
 370                                 walk_pud_level(m, &st, *start,
 371                                                i * PGD_LEVEL_MULT);
 372                 } else
 373                         note_page(m, &st, __pgprot(0), 1);
 374
 375                 start++;
 376         }
 377
 378         /* Flush out the last page */
 379         st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
 380         note_page(m, &st, __pgprot(0), 0);
 381 }
 382
 383 static int ptdump_show(struct seq_file *m, void *v)
 384 {
 385         ptdump_walk_pgd_level(m, NULL);
 386         return 0;
 387 }
 388
 389 static int ptdump_open(struct inode *inode, struct file *filp)
 390 {
 391         return single_open(filp, ptdump_show, NULL);
 392 }
 393
 394 static const struct file_operations ptdump_fops = {
 395         .open           = ptdump_open,
 396         .read           = seq_read,
 397         .llseek         = seq_lseek,
 398         .release        = single_release,
 399 };
 400
 401 static int pt_dump_init(void)
 402 {
 403         struct dentry *pe;
 404
 405 #ifdef CONFIG_X86_32
 406         /* Not a compile-time constant on x86-32 */
 407         address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
 408         address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
 409 # ifdef CONFIG_HIGHMEM
 410         address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
 411 # endif
 412         address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
 413 #endif
 414
 415         pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL,
 416                                  &ptdump_fops);
 417         if (!pe)
 418                 return -ENOMEM;
 419
 420         return 0;
 421 }
 422
 423 __initcall(pt_dump_init);
 424 MODULE_LICENSE("GPL");
 425 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
 426 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");