arch/powerpc/mm/dump_linuxpagetables.c

   1 /*
   2  * Copyright 2016, Rashmica Gupta, IBM Corp.
   3  *
   4  * This traverses the kernel pagetables and dumps the
   5  * information about the used sections of memory to
   6  * /sys/kernel/debug/kernel_pagetables.
   7  *
   8  * Derived from the arm64 implementation:
   9  * Copyright (c) 2014, The Linux Foundation, Laura Abbott.
  10  * (C) Copyright 2008 Intel Corporation, Arjan van de Ven.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; version 2
  15  * of the License.
  16  */
  17 #include <linux/debugfs.h>
  18 #include <linux/fs.h>
  19 #include <linux/io.h>
  20 #include <linux/mm.h>
  21 #include <linux/sched.h>
  22 #include <linux/seq_file.h>
  23 #include <asm/fixmap.h>
  24 #include <asm/pgtable.h>
  25 #include <linux/const.h>
  26 #include <asm/page.h>
  27 #include <asm/pgalloc.h>
  28
  29 #ifdef CONFIG_PPC32
  30 #define KERN_VIRT_START 0
  31 #endif
  32
  33 /*
  34  * To visualise what is happening,
  35  *
  36  *  - PTRS_PER_P** = how many entries there are in the corresponding P**
  37  *  - P**_SHIFT = how many bits of the address we use to index into the
  38  * corresponding P**
  39  *  - P**_SIZE is how much memory we can access through the table - not the
  40  * size of the table itself.
  41  * P**={PGD, PUD, PMD, PTE}
  42  *
  43  *
  44  * Each entry of the PGD points to a PUD. Each entry of a PUD points to a
  45  * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to
  46  * a page.
  47  *
  48  * In the case where there are only 3 levels, the PUD is folded into the
  49  * PGD: every PUD has only one entry which points to the PMD.
  50  *
  51  * The page dumper groups page table entries of the same type into a single
  52  * description. It uses pg_state to track the range information while
  53  * iterating over the PTE entries. When the continuity is broken it then
  54  * dumps out a description of the range - ie PTEs that are virtually contiguous
  55  * with the same PTE flags are chunked together. This is to make it clear how
  56  * different areas of the kernel virtual memory are used.
  57  *
  58  */
  59 struct pg_state {
  60         struct seq_file *seq;
  61         const struct addr_marker *marker;
  62         unsigned long start_address;
  63         unsigned long start_pa;
  64         unsigned long last_pa;
  65         unsigned int level;
  66         u64 current_flags;
  67 };
  68
  69 struct addr_marker {
  70         unsigned long start_address;
  71         const char *name;
  72 };
  73
  74 static struct addr_marker address_markers[] = {
  75         { 0,    "Start of kernel VM" },
  76         { 0,    "vmalloc() Area" },
  77         { 0,    "vmalloc() End" },
  78 #ifdef CONFIG_PPC64
  79         { 0,    "isa I/O start" },
  80         { 0,    "isa I/O end" },
  81         { 0,    "phb I/O start" },
  82         { 0,    "phb I/O end" },
  83         { 0,    "I/O remap start" },
  84         { 0,    "I/O remap end" },
  85         { 0,    "vmemmap start" },
  86 #else
  87         { 0,    "Early I/O remap start" },
  88         { 0,    "Early I/O remap end" },
  89 #ifdef CONFIG_NOT_COHERENT_CACHE
  90         { 0,    "Consistent mem start" },
  91         { 0,    "Consistent mem end" },
  92 #endif
  93 #ifdef CONFIG_HIGHMEM
  94         { 0,    "Highmem PTEs start" },
  95         { 0,    "Highmem PTEs end" },
  96 #endif
  97         { 0,    "Fixmap start" },
  98         { 0,    "Fixmap end" },
  99 #endif
 100         { -1,   NULL },
 101 };
 102
 103 struct flag_info {
 104         u64             mask;
 105         u64             val;
 106         const char      *set;
 107         const char      *clear;
 108         bool            is_val;
 109         int             shift;
 110 };
 111
 112 static const struct flag_info flag_array[] = {
 113         {
 114 #ifdef CONFIG_PPC_STD_MMU_64
 115                 .mask   = _PAGE_PRIVILEGED,
 116                 .val    = 0,
 117 #else
 118                 .mask   = _PAGE_USER,
 119                 .val    = _PAGE_USER,
 120 #endif
 121                 .set    = "user",
 122                 .clear  = "    ",
 123         }, {
 124 #if _PAGE_RO == 0
 125                 .mask   = _PAGE_RW,
 126                 .val    = _PAGE_RW,
 127 #else
 128                 .mask   = _PAGE_RO,
 129                 .val    = 0,
 130 #endif
 131                 .set    = "rw",
 132                 .clear  = "ro",
 133         }, {
 134                 .mask   = _PAGE_EXEC,
 135                 .val    = _PAGE_EXEC,
 136                 .set    = " X ",
 137                 .clear  = "   ",
 138         }, {
 139                 .mask   = _PAGE_PTE,
 140                 .val    = _PAGE_PTE,
 141                 .set    = "pte",
 142                 .clear  = "   ",
 143         }, {
 144                 .mask   = _PAGE_PRESENT,
 145                 .val    = _PAGE_PRESENT,
 146                 .set    = "present",
 147                 .clear  = "       ",
 148         }, {
 149 #ifdef CONFIG_PPC_STD_MMU_64
 150                 .mask   = H_PAGE_HASHPTE,
 151                 .val    = H_PAGE_HASHPTE,
 152 #else
 153                 .mask   = _PAGE_HASHPTE,
 154                 .val    = _PAGE_HASHPTE,
 155 #endif
 156                 .set    = "hpte",
 157                 .clear  = "    ",
 158         }, {
 159 #ifndef CONFIG_PPC_STD_MMU_64
 160                 .mask   = _PAGE_GUARDED,
 161                 .val    = _PAGE_GUARDED,
 162                 .set    = "guarded",
 163                 .clear  = "       ",
 164         }, {
 165 #endif
 166                 .mask   = _PAGE_DIRTY,
 167                 .val    = _PAGE_DIRTY,
 168                 .set    = "dirty",
 169                 .clear  = "     ",
 170         }, {
 171                 .mask   = _PAGE_ACCESSED,
 172                 .val    = _PAGE_ACCESSED,
 173                 .set    = "accessed",
 174                 .clear  = "        ",
 175         }, {
 176 #ifndef CONFIG_PPC_STD_MMU_64
 177                 .mask   = _PAGE_WRITETHRU,
 178                 .val    = _PAGE_WRITETHRU,
 179                 .set    = "write through",
 180                 .clear  = "             ",
 181         }, {
 182 #endif
 183 #ifndef CONFIG_PPC_BOOK3S_64
 184                 .mask   = _PAGE_NO_CACHE,
 185                 .val    = _PAGE_NO_CACHE,
 186                 .set    = "no cache",
 187                 .clear  = "        ",
 188         }, {
 189 #else
 190                 .mask   = _PAGE_NON_IDEMPOTENT,
 191                 .val    = _PAGE_NON_IDEMPOTENT,
 192                 .set    = "non-idempotent",
 193                 .clear  = "              ",
 194         }, {
 195                 .mask   = _PAGE_TOLERANT,
 196                 .val    = _PAGE_TOLERANT,
 197                 .set    = "tolerant",
 198                 .clear  = "        ",
 199         }, {
 200 #endif
 201 #ifdef CONFIG_PPC_BOOK3S_64
 202                 .mask   = H_PAGE_BUSY,
 203                 .val    = H_PAGE_BUSY,
 204                 .set    = "busy",
 205         }, {
 206 #ifdef CONFIG_PPC_64K_PAGES
 207                 .mask   = H_PAGE_COMBO,
 208                 .val    = H_PAGE_COMBO,
 209                 .set    = "combo",
 210         }, {
 211                 .mask   = H_PAGE_4K_PFN,
 212                 .val    = H_PAGE_4K_PFN,
 213                 .set    = "4K_pfn",
 214         }, {
 215 #endif
 216                 .mask   = H_PAGE_F_GIX,
 217                 .val    = H_PAGE_F_GIX,
 218                 .set    = "f_gix",
 219                 .is_val = true,
 220                 .shift  = H_PAGE_F_GIX_SHIFT,
 221         }, {
 222                 .mask   = H_PAGE_F_SECOND,
 223                 .val    = H_PAGE_F_SECOND,
 224                 .set    = "f_second",
 225         }, {
 226 #endif
 227                 .mask   = _PAGE_SPECIAL,
 228                 .val    = _PAGE_SPECIAL,
 229                 .set    = "special",
 230         }, {
 231                 .mask   = _PAGE_SHARED,
 232                 .val    = _PAGE_SHARED,
 233                 .set    = "shared",
 234         }
 235 };
 236
 237 struct pgtable_level {
 238         const struct flag_info *flag;
 239         size_t num;
 240         u64 mask;
 241 };
 242
 243 static struct pgtable_level pg_level[] = {
 244         {
 245         }, { /* pgd */
 246                 .flag   = flag_array,
 247                 .num    = ARRAY_SIZE(flag_array),
 248         }, { /* pud */
 249                 .flag   = flag_array,
 250                 .num    = ARRAY_SIZE(flag_array),
 251         }, { /* pmd */
 252                 .flag   = flag_array,
 253                 .num    = ARRAY_SIZE(flag_array),
 254         }, { /* pte */
 255                 .flag   = flag_array,
 256                 .num    = ARRAY_SIZE(flag_array),
 257         },
 258 };
 259
 260 static void dump_flag_info(struct pg_state *st, const struct flag_info
 261                 *flag, u64 pte, int num)
 262 {
 263         unsigned int i;
 264
 265         for (i = 0; i < num; i++, flag++) {
 266                 const char *s = NULL;
 267                 u64 val;
 268
 269                 /* flag not defined so don't check it */
 270                 if (flag->mask == 0)
 271                         continue;
 272                 /* Some 'flags' are actually values */
 273                 if (flag->is_val) {
 274                         val = pte & flag->val;
 275                         if (flag->shift)
 276                                 val = val >> flag->shift;
 277                         seq_printf(st->seq, "  %s:%llx", flag->set, val);
 278                 } else {
 279                         if ((pte & flag->mask) == flag->val)
 280                                 s = flag->set;
 281                         else
 282                                 s = flag->clear;
 283                         if (s)
 284                                 seq_printf(st->seq, "  %s", s);
 285                 }
 286                 st->current_flags &= ~flag->mask;
 287         }
 288         if (st->current_flags != 0)
 289                 seq_printf(st->seq, "  unknown flags:%llx", st->current_flags);
 290 }
 291
 292 static void dump_addr(struct pg_state *st, unsigned long addr)
 293 {
 294         static const char units[] = "KMGTPE";
 295         const char *unit = units;
 296         unsigned long delta;
 297
 298 #ifdef CONFIG_PPC64
 299         seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1);
 300         seq_printf(st->seq, "0x%016lx ", st->start_pa);
 301 #else
 302         seq_printf(st->seq, "0x%08lx-0x%08lx ", st->start_address, addr - 1);
 303         seq_printf(st->seq, "0x%08lx ", st->start_pa);
 304 #endif
 305
 306         delta = (addr - st->start_address) >> 10;
 307         /* Work out what appropriate unit to use */
 308         while (!(delta & 1023) && unit[1]) {
 309                 delta >>= 10;
 310                 unit++;
 311         }
 312         seq_printf(st->seq, "%9lu%c", delta, *unit);
 313
 314 }
 315
 316 static void note_page(struct pg_state *st, unsigned long addr,
 317                unsigned int level, u64 val)
 318 {
 319         u64 flag = val & pg_level[level].mask;
 320         u64 pa = val & PTE_RPN_MASK;
 321
 322         /* At first no level is set */
 323         if (!st->level) {
 324                 st->level = level;
 325                 st->current_flags = flag;
 326                 st->start_address = addr;
 327                 st->start_pa = pa;
 328                 st->last_pa = pa;
 329                 seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 330         /*
 331          * Dump the section of virtual memory when:
 332          *   - the PTE flags from one entry to the next differs.
 333          *   - we change levels in the tree.
 334          *   - the address is in a different section of memory and is thus
 335          *   used for a different purpose, regardless of the flags.
 336          *   - the pa of this page is not adjacent to the last inspected page
 337          */
 338         } else if (flag != st->current_flags || level != st->level ||
 339                    addr >= st->marker[1].start_address ||
 340                    pa != st->last_pa + PAGE_SIZE) {
 341
 342                 /* Check the PTE flags */
 343                 if (st->current_flags) {
 344                         dump_addr(st, addr);
 345
 346                         /* Dump all the flags */
 347                         if (pg_level[st->level].flag)
 348                                 dump_flag_info(st, pg_level[st->level].flag,
 349                                           st->current_flags,
 350                                           pg_level[st->level].num);
 351
 352                         seq_puts(st->seq, "\n");
 353                 }
 354
 355                 /*
 356                  * Address indicates we have passed the end of the
 357                  * current section of virtual memory
 358                  */
 359                 while (addr >= st->marker[1].start_address) {
 360                         st->marker++;
 361                         seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 362                 }
 363                 st->start_address = addr;
 364                 st->start_pa = pa;
 365                 st->last_pa = pa;
 366                 st->current_flags = flag;
 367                 st->level = level;
 368         } else {
 369                 st->last_pa = pa;
 370         }
 371 }
 372
 373 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
 374 {
 375         pte_t *pte = pte_offset_kernel(pmd, 0);
 376         unsigned long addr;
 377         unsigned int i;
 378
 379         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 380                 addr = start + i * PAGE_SIZE;
 381                 note_page(st, addr, 4, pte_val(*pte));
 382
 383         }
 384 }
 385
 386 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 387 {
 388         pmd_t *pmd = pmd_offset(pud, 0);
 389         unsigned long addr;
 390         unsigned int i;
 391
 392         for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 393                 addr = start + i * PMD_SIZE;
 394                 if (!pmd_none(*pmd))
 395                         /* pmd exists */
 396                         walk_pte(st, pmd, addr);
 397                 else
 398                         note_page(st, addr, 3, pmd_val(*pmd));
 399         }
 400 }
 401
 402 static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
 403 {
 404         pud_t *pud = pud_offset(pgd, 0);
 405         unsigned long addr;
 406         unsigned int i;
 407
 408         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 409                 addr = start + i * PUD_SIZE;
 410                 if (!pud_none(*pud))
 411                         /* pud exists */
 412                         walk_pmd(st, pud, addr);
 413                 else
 414                         note_page(st, addr, 2, pud_val(*pud));
 415         }
 416 }
 417
 418 static void walk_pagetables(struct pg_state *st)
 419 {
 420         pgd_t *pgd = pgd_offset_k(0UL);
 421         unsigned int i;
 422         unsigned long addr;
 423
 424         /*
 425          * Traverse the linux pagetable structure and dump pages that are in
 426          * the hash pagetable.
 427          */
 428         for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
 429                 addr = KERN_VIRT_START + i * PGDIR_SIZE;
 430                 if (!pgd_none(*pgd))
 431                         /* pgd exists */
 432                         walk_pud(st, pgd, addr);
 433                 else
 434                         note_page(st, addr, 1, pgd_val(*pgd));
 435         }
 436 }
 437
 438 static void populate_markers(void)
 439 {
 440         int i = 0;
 441
 442         address_markers[i++].start_address = PAGE_OFFSET;
 443         address_markers[i++].start_address = VMALLOC_START;
 444         address_markers[i++].start_address = VMALLOC_END;
 445 #ifdef CONFIG_PPC64
 446         address_markers[i++].start_address = ISA_IO_BASE;
 447         address_markers[i++].start_address = ISA_IO_END;
 448         address_markers[i++].start_address = PHB_IO_BASE;
 449         address_markers[i++].start_address = PHB_IO_END;
 450         address_markers[i++].start_address = IOREMAP_BASE;
 451         address_markers[i++].start_address = IOREMAP_END;
 452 #ifdef CONFIG_PPC_STD_MMU_64
 453         address_markers[i++].start_address =  H_VMEMMAP_BASE;
 454 #else
 455         address_markers[i++].start_address =  VMEMMAP_BASE;
 456 #endif
 457 #else /* !CONFIG_PPC64 */
 458         address_markers[i++].start_address = ioremap_bot;
 459         address_markers[i++].start_address = IOREMAP_TOP;
 460 #ifdef CONFIG_NOT_COHERENT_CACHE
 461         address_markers[i++].start_address = IOREMAP_TOP;
 462         address_markers[i++].start_address = IOREMAP_TOP +
 463                                              CONFIG_CONSISTENT_SIZE;
 464 #endif
 465 #ifdef CONFIG_HIGHMEM
 466         address_markers[i++].start_address = PKMAP_BASE;
 467         address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
 468 #endif
 469         address_markers[i++].start_address = FIXADDR_START;
 470         address_markers[i++].start_address = FIXADDR_TOP;
 471 #endif /* CONFIG_PPC64 */
 472 }
 473
 474 static int ptdump_show(struct seq_file *m, void *v)
 475 {
 476         struct pg_state st = {
 477                 .seq = m,
 478                 .start_address = KERN_VIRT_START,
 479                 .marker = address_markers,
 480         };
 481         /* Traverse kernel page tables */
 482         walk_pagetables(&st);
 483         note_page(&st, 0, 0, 0);
 484         return 0;
 485 }
 486
 487
 488 static int ptdump_open(struct inode *inode, struct file *file)
 489 {
 490         return single_open(file, ptdump_show, NULL);
 491 }
 492
 493 static const struct file_operations ptdump_fops = {
 494         .open           = ptdump_open,
 495         .read           = seq_read,
 496         .llseek         = seq_lseek,
 497         .release        = single_release,
 498 };
 499
 500 static void build_pgtable_complete_mask(void)
 501 {
 502         unsigned int i, j;
 503
 504         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 505                 if (pg_level[i].flag)
 506                         for (j = 0; j < pg_level[i].num; j++)
 507                                 pg_level[i].mask |= pg_level[i].flag[j].mask;
 508 }
 509
 510 static int ptdump_init(void)
 511 {
 512         struct dentry *debugfs_file;
 513
 514         populate_markers();
 515         build_pgtable_complete_mask();
 516         debugfs_file = debugfs_create_file("kernel_page_tables", 0400, NULL,
 517                         NULL, &ptdump_fops);
 518         return debugfs_file ? 0 : -ENOMEM;
 519 }
 520 device_initcall(ptdump_init);