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/hugetlb.h>
  20 #include <linux/io.h>
  21 #include <linux/mm.h>
  22 #include <linux/sched.h>
  23 #include <linux/seq_file.h>
  24 #include <asm/fixmap.h>
  25 #include <asm/pgtable.h>
  26 #include <linux/const.h>
  27 #include <asm/page.h>
  28 #include <asm/pgalloc.h>
  29
  30 #ifdef CONFIG_PPC32
  31 #define KERN_VIRT_START 0
  32 #endif
  33
  34 /*
  35  * To visualise what is happening,
  36  *
  37  *  - PTRS_PER_P** = how many entries there are in the corresponding P**
  38  *  - P**_SHIFT = how many bits of the address we use to index into the
  39  * corresponding P**
  40  *  - P**_SIZE is how much memory we can access through the table - not the
  41  * size of the table itself.
  42  * P**={PGD, PUD, PMD, PTE}
  43  *
  44  *
  45  * Each entry of the PGD points to a PUD. Each entry of a PUD points to a
  46  * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to
  47  * a page.
  48  *
  49  * In the case where there are only 3 levels, the PUD is folded into the
  50  * PGD: every PUD has only one entry which points to the PMD.
  51  *
  52  * The page dumper groups page table entries of the same type into a single
  53  * description. It uses pg_state to track the range information while
  54  * iterating over the PTE entries. When the continuity is broken it then
  55  * dumps out a description of the range - ie PTEs that are virtually contiguous
  56  * with the same PTE flags are chunked together. This is to make it clear how
  57  * different areas of the kernel virtual memory are used.
  58  *
  59  */
  60 struct pg_state {
  61         struct seq_file *seq;
  62         const struct addr_marker *marker;
  63         unsigned long start_address;
  64         unsigned long start_pa;
  65         unsigned long last_pa;
  66         unsigned int level;
  67         u64 current_flags;
  68 };
  69
  70 struct addr_marker {
  71         unsigned long start_address;
  72         const char *name;
  73 };
  74
  75 static struct addr_marker address_markers[] = {
  76         { 0,    "Start of kernel VM" },
  77         { 0,    "vmalloc() Area" },
  78         { 0,    "vmalloc() End" },
  79 #ifdef CONFIG_PPC64
  80         { 0,    "isa I/O start" },
  81         { 0,    "isa I/O end" },
  82         { 0,    "phb I/O start" },
  83         { 0,    "phb I/O end" },
  84         { 0,    "I/O remap start" },
  85         { 0,    "I/O remap end" },
  86         { 0,    "vmemmap start" },
  87 #else
  88         { 0,    "Early I/O remap start" },
  89         { 0,    "Early I/O remap end" },
  90 #ifdef CONFIG_NOT_COHERENT_CACHE
  91         { 0,    "Consistent mem start" },
  92         { 0,    "Consistent mem end" },
  93 #endif
  94 #ifdef CONFIG_HIGHMEM
  95         { 0,    "Highmem PTEs start" },
  96         { 0,    "Highmem PTEs end" },
  97 #endif
  98         { 0,    "Fixmap start" },
  99         { 0,    "Fixmap end" },
 100 #endif
 101         { -1,   NULL },
 102 };
 103
 104 struct flag_info {
 105         u64             mask;
 106         u64             val;
 107         const char      *set;
 108         const char      *clear;
 109         bool            is_val;
 110         int             shift;
 111 };
 112
 113 static const struct flag_info flag_array[] = {
 114         {
 115                 .mask   = _PAGE_USER | _PAGE_PRIVILEGED,
 116                 .val    = _PAGE_USER,
 117                 .set    = "user",
 118                 .clear  = "    ",
 119         }, {
 120                 .mask   = _PAGE_RW | _PAGE_RO | _PAGE_NA,
 121                 .val    = _PAGE_RW,
 122                 .set    = "rw",
 123         }, {
 124                 .mask   = _PAGE_RW | _PAGE_RO | _PAGE_NA,
 125                 .val    = _PAGE_RO,
 126                 .set    = "ro",
 127         }, {
 128 #if _PAGE_NA != 0
 129                 .mask   = _PAGE_RW | _PAGE_RO | _PAGE_NA,
 130                 .val    = _PAGE_RO,
 131                 .set    = "na",
 132         }, {
 133 #endif
 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_BOOK3S_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_BOOK3S_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_BOOK3S_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 #else /* CONFIG_PPC_64K_PAGES */
 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 /* CONFIG_PPC_64K_PAGES */
 227 #endif
 228                 .mask   = _PAGE_SPECIAL,
 229                 .val    = _PAGE_SPECIAL,
 230                 .set    = "special",
 231         }
 232 };
 233
 234 struct pgtable_level {
 235         const struct flag_info *flag;
 236         size_t num;
 237         u64 mask;
 238 };
 239
 240 static struct pgtable_level pg_level[] = {
 241         {
 242         }, { /* pgd */
 243                 .flag   = flag_array,
 244                 .num    = ARRAY_SIZE(flag_array),
 245         }, { /* pud */
 246                 .flag   = flag_array,
 247                 .num    = ARRAY_SIZE(flag_array),
 248         }, { /* pmd */
 249                 .flag   = flag_array,
 250                 .num    = ARRAY_SIZE(flag_array),
 251         }, { /* pte */
 252                 .flag   = flag_array,
 253                 .num    = ARRAY_SIZE(flag_array),
 254         },
 255 };
 256
 257 static void dump_flag_info(struct pg_state *st, const struct flag_info
 258                 *flag, u64 pte, int num)
 259 {
 260         unsigned int i;
 261
 262         for (i = 0; i < num; i++, flag++) {
 263                 const char *s = NULL;
 264                 u64 val;
 265
 266                 /* flag not defined so don't check it */
 267                 if (flag->mask == 0)
 268                         continue;
 269                 /* Some 'flags' are actually values */
 270                 if (flag->is_val) {
 271                         val = pte & flag->val;
 272                         if (flag->shift)
 273                                 val = val >> flag->shift;
 274                         seq_printf(st->seq, "  %s:%llx", flag->set, val);
 275                 } else {
 276                         if ((pte & flag->mask) == flag->val)
 277                                 s = flag->set;
 278                         else
 279                                 s = flag->clear;
 280                         if (s)
 281                                 seq_printf(st->seq, "  %s", s);
 282                 }
 283                 st->current_flags &= ~flag->mask;
 284         }
 285         if (st->current_flags != 0)
 286                 seq_printf(st->seq, "  unknown flags:%llx", st->current_flags);
 287 }
 288
 289 static void dump_addr(struct pg_state *st, unsigned long addr)
 290 {
 291         static const char units[] = "KMGTPE";
 292         const char *unit = units;
 293         unsigned long delta;
 294
 295 #ifdef CONFIG_PPC64
 296         seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1);
 297         seq_printf(st->seq, "0x%016lx ", st->start_pa);
 298 #else
 299         seq_printf(st->seq, "0x%08lx-0x%08lx ", st->start_address, addr - 1);
 300         seq_printf(st->seq, "0x%08lx ", st->start_pa);
 301 #endif
 302
 303         delta = (addr - st->start_address) >> 10;
 304         /* Work out what appropriate unit to use */
 305         while (!(delta & 1023) && unit[1]) {
 306                 delta >>= 10;
 307                 unit++;
 308         }
 309         seq_printf(st->seq, "%9lu%c", delta, *unit);
 310
 311 }
 312
 313 static void note_page(struct pg_state *st, unsigned long addr,
 314                unsigned int level, u64 val)
 315 {
 316         u64 flag = val & pg_level[level].mask;
 317         u64 pa = val & PTE_RPN_MASK;
 318
 319         /* At first no level is set */
 320         if (!st->level) {
 321                 st->level = level;
 322                 st->current_flags = flag;
 323                 st->start_address = addr;
 324                 st->start_pa = pa;
 325                 st->last_pa = pa;
 326                 seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 327         /*
 328          * Dump the section of virtual memory when:
 329          *   - the PTE flags from one entry to the next differs.
 330          *   - we change levels in the tree.
 331          *   - the address is in a different section of memory and is thus
 332          *   used for a different purpose, regardless of the flags.
 333          *   - the pa of this page is not adjacent to the last inspected page
 334          */
 335         } else if (flag != st->current_flags || level != st->level ||
 336                    addr >= st->marker[1].start_address ||
 337                    pa != st->last_pa + PAGE_SIZE) {
 338
 339                 /* Check the PTE flags */
 340                 if (st->current_flags) {
 341                         dump_addr(st, addr);
 342
 343                         /* Dump all the flags */
 344                         if (pg_level[st->level].flag)
 345                                 dump_flag_info(st, pg_level[st->level].flag,
 346                                           st->current_flags,
 347                                           pg_level[st->level].num);
 348
 349                         seq_putc(st->seq, '\n');
 350                 }
 351
 352                 /*
 353                  * Address indicates we have passed the end of the
 354                  * current section of virtual memory
 355                  */
 356                 while (addr >= st->marker[1].start_address) {
 357                         st->marker++;
 358                         seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 359                 }
 360                 st->start_address = addr;
 361                 st->start_pa = pa;
 362                 st->last_pa = pa;
 363                 st->current_flags = flag;
 364                 st->level = level;
 365         } else {
 366                 st->last_pa = pa;
 367         }
 368 }
 369
 370 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
 371 {
 372         pte_t *pte = pte_offset_kernel(pmd, 0);
 373         unsigned long addr;
 374         unsigned int i;
 375
 376         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 377                 addr = start + i * PAGE_SIZE;
 378                 note_page(st, addr, 4, pte_val(*pte));
 379
 380         }
 381 }
 382
 383 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 384 {
 385         pmd_t *pmd = pmd_offset(pud, 0);
 386         unsigned long addr;
 387         unsigned int i;
 388
 389         for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 390                 addr = start + i * PMD_SIZE;
 391                 if (!pmd_none(*pmd) && !pmd_huge(*pmd))
 392                         /* pmd exists */
 393                         walk_pte(st, pmd, addr);
 394                 else
 395                         note_page(st, addr, 3, pmd_val(*pmd));
 396         }
 397 }
 398
 399 static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
 400 {
 401         pud_t *pud = pud_offset(pgd, 0);
 402         unsigned long addr;
 403         unsigned int i;
 404
 405         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 406                 addr = start + i * PUD_SIZE;
 407                 if (!pud_none(*pud) && !pud_huge(*pud))
 408                         /* pud exists */
 409                         walk_pmd(st, pud, addr);
 410                 else
 411                         note_page(st, addr, 2, pud_val(*pud));
 412         }
 413 }
 414
 415 static void walk_pagetables(struct pg_state *st)
 416 {
 417         pgd_t *pgd = pgd_offset_k(0UL);
 418         unsigned int i;
 419         unsigned long addr;
 420
 421         /*
 422          * Traverse the linux pagetable structure and dump pages that are in
 423          * the hash pagetable.
 424          */
 425         for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
 426                 addr = KERN_VIRT_START + i * PGDIR_SIZE;
 427                 if (!pgd_none(*pgd) && !pgd_huge(*pgd))
 428                         /* pgd exists */
 429                         walk_pud(st, pgd, addr);
 430                 else
 431                         note_page(st, addr, 1, pgd_val(*pgd));
 432         }
 433 }
 434
 435 static void populate_markers(void)
 436 {
 437         int i = 0;
 438
 439         address_markers[i++].start_address = PAGE_OFFSET;
 440         address_markers[i++].start_address = VMALLOC_START;
 441         address_markers[i++].start_address = VMALLOC_END;
 442 #ifdef CONFIG_PPC64
 443         address_markers[i++].start_address = ISA_IO_BASE;
 444         address_markers[i++].start_address = ISA_IO_END;
 445         address_markers[i++].start_address = PHB_IO_BASE;
 446         address_markers[i++].start_address = PHB_IO_END;
 447         address_markers[i++].start_address = IOREMAP_BASE;
 448         address_markers[i++].start_address = IOREMAP_END;
 449 #ifdef CONFIG_PPC_BOOK3S_64
 450         address_markers[i++].start_address =  H_VMEMMAP_BASE;
 451 #else
 452         address_markers[i++].start_address =  VMEMMAP_BASE;
 453 #endif
 454 #else /* !CONFIG_PPC64 */
 455         address_markers[i++].start_address = ioremap_bot;
 456         address_markers[i++].start_address = IOREMAP_TOP;
 457 #ifdef CONFIG_NOT_COHERENT_CACHE
 458         address_markers[i++].start_address = IOREMAP_TOP;
 459         address_markers[i++].start_address = IOREMAP_TOP +
 460                                              CONFIG_CONSISTENT_SIZE;
 461 #endif
 462 #ifdef CONFIG_HIGHMEM
 463         address_markers[i++].start_address = PKMAP_BASE;
 464         address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
 465 #endif
 466         address_markers[i++].start_address = FIXADDR_START;
 467         address_markers[i++].start_address = FIXADDR_TOP;
 468 #endif /* CONFIG_PPC64 */
 469 }
 470
 471 static int ptdump_show(struct seq_file *m, void *v)
 472 {
 473         struct pg_state st = {
 474                 .seq = m,
 475                 .start_address = KERN_VIRT_START,
 476                 .marker = address_markers,
 477         };
 478         /* Traverse kernel page tables */
 479         walk_pagetables(&st);
 480         note_page(&st, 0, 0, 0);
 481         return 0;
 482 }
 483
 484
 485 static int ptdump_open(struct inode *inode, struct file *file)
 486 {
 487         return single_open(file, ptdump_show, NULL);
 488 }
 489
 490 static const struct file_operations ptdump_fops = {
 491         .open           = ptdump_open,
 492         .read           = seq_read,
 493         .llseek         = seq_lseek,
 494         .release        = single_release,
 495 };
 496
 497 static void build_pgtable_complete_mask(void)
 498 {
 499         unsigned int i, j;
 500
 501         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 502                 if (pg_level[i].flag)
 503                         for (j = 0; j < pg_level[i].num; j++)
 504                                 pg_level[i].mask |= pg_level[i].flag[j].mask;
 505 }
 506
 507 static int ptdump_init(void)
 508 {
 509         struct dentry *debugfs_file;
 510
 511         populate_markers();
 512         build_pgtable_complete_mask();
 513         debugfs_file = debugfs_create_file("kernel_page_tables", 0400, NULL,
 514                         NULL, &ptdump_fops);
 515         return debugfs_file ? 0 : -ENOMEM;
 516 }
 517 device_initcall(ptdump_init);