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 #ifdef CONFIG_PPC_STD_MMU_64
 116                 .mask   = _PAGE_PRIVILEGED,
 117                 .val    = 0,
 118 #else
 119                 .mask   = _PAGE_USER,
 120                 .val    = _PAGE_USER,
 121 #endif
 122                 .set    = "user",
 123                 .clear  = "    ",
 124         }, {
 125 #if _PAGE_RO == 0
 126                 .mask   = _PAGE_RW,
 127                 .val    = _PAGE_RW,
 128 #else
 129                 .mask   = _PAGE_RO,
 130                 .val    = 0,
 131 #endif
 132                 .set    = "rw",
 133                 .clear  = "ro",
 134         }, {
 135                 .mask   = _PAGE_EXEC,
 136                 .val    = _PAGE_EXEC,
 137                 .set    = " X ",
 138                 .clear  = "   ",
 139         }, {
 140                 .mask   = _PAGE_PTE,
 141                 .val    = _PAGE_PTE,
 142                 .set    = "pte",
 143                 .clear  = "   ",
 144         }, {
 145                 .mask   = _PAGE_PRESENT,
 146                 .val    = _PAGE_PRESENT,
 147                 .set    = "present",
 148                 .clear  = "       ",
 149         }, {
 150 #ifdef CONFIG_PPC_STD_MMU_64
 151                 .mask   = H_PAGE_HASHPTE,
 152                 .val    = H_PAGE_HASHPTE,
 153 #else
 154                 .mask   = _PAGE_HASHPTE,
 155                 .val    = _PAGE_HASHPTE,
 156 #endif
 157                 .set    = "hpte",
 158                 .clear  = "    ",
 159         }, {
 160 #ifndef CONFIG_PPC_STD_MMU_64
 161                 .mask   = _PAGE_GUARDED,
 162                 .val    = _PAGE_GUARDED,
 163                 .set    = "guarded",
 164                 .clear  = "       ",
 165         }, {
 166 #endif
 167                 .mask   = _PAGE_DIRTY,
 168                 .val    = _PAGE_DIRTY,
 169                 .set    = "dirty",
 170                 .clear  = "     ",
 171         }, {
 172                 .mask   = _PAGE_ACCESSED,
 173                 .val    = _PAGE_ACCESSED,
 174                 .set    = "accessed",
 175                 .clear  = "        ",
 176         }, {
 177 #ifndef CONFIG_PPC_STD_MMU_64
 178                 .mask   = _PAGE_WRITETHRU,
 179                 .val    = _PAGE_WRITETHRU,
 180                 .set    = "write through",
 181                 .clear  = "             ",
 182         }, {
 183 #endif
 184 #ifndef CONFIG_PPC_BOOK3S_64
 185                 .mask   = _PAGE_NO_CACHE,
 186                 .val    = _PAGE_NO_CACHE,
 187                 .set    = "no cache",
 188                 .clear  = "        ",
 189         }, {
 190 #else
 191                 .mask   = _PAGE_NON_IDEMPOTENT,
 192                 .val    = _PAGE_NON_IDEMPOTENT,
 193                 .set    = "non-idempotent",
 194                 .clear  = "              ",
 195         }, {
 196                 .mask   = _PAGE_TOLERANT,
 197                 .val    = _PAGE_TOLERANT,
 198                 .set    = "tolerant",
 199                 .clear  = "        ",
 200         }, {
 201 #endif
 202 #ifdef CONFIG_PPC_BOOK3S_64
 203                 .mask   = H_PAGE_BUSY,
 204                 .val    = H_PAGE_BUSY,
 205                 .set    = "busy",
 206         }, {
 207 #ifdef CONFIG_PPC_64K_PAGES
 208                 .mask   = H_PAGE_COMBO,
 209                 .val    = H_PAGE_COMBO,
 210                 .set    = "combo",
 211         }, {
 212                 .mask   = H_PAGE_4K_PFN,
 213                 .val    = H_PAGE_4K_PFN,
 214                 .set    = "4K_pfn",
 215         }, {
 216 #endif
 217                 .mask   = H_PAGE_F_GIX,
 218                 .val    = H_PAGE_F_GIX,
 219                 .set    = "f_gix",
 220                 .is_val = true,
 221                 .shift  = H_PAGE_F_GIX_SHIFT,
 222         }, {
 223                 .mask   = H_PAGE_F_SECOND,
 224                 .val    = H_PAGE_F_SECOND,
 225                 .set    = "f_second",
 226         }, {
 227 #endif
 228                 .mask   = _PAGE_SPECIAL,
 229                 .val    = _PAGE_SPECIAL,
 230                 .set    = "special",
 231         }, {
 232                 .mask   = _PAGE_SHARED,
 233                 .val    = _PAGE_SHARED,
 234                 .set    = "shared",
 235         }
 236 };
 237
 238 struct pgtable_level {
 239         const struct flag_info *flag;
 240         size_t num;
 241         u64 mask;
 242 };
 243
 244 static struct pgtable_level pg_level[] = {
 245         {
 246         }, { /* pgd */
 247                 .flag   = flag_array,
 248                 .num    = ARRAY_SIZE(flag_array),
 249         }, { /* pud */
 250                 .flag   = flag_array,
 251                 .num    = ARRAY_SIZE(flag_array),
 252         }, { /* pmd */
 253                 .flag   = flag_array,
 254                 .num    = ARRAY_SIZE(flag_array),
 255         }, { /* pte */
 256                 .flag   = flag_array,
 257                 .num    = ARRAY_SIZE(flag_array),
 258         },
 259 };
 260
 261 static void dump_flag_info(struct pg_state *st, const struct flag_info
 262                 *flag, u64 pte, int num)
 263 {
 264         unsigned int i;
 265
 266         for (i = 0; i < num; i++, flag++) {
 267                 const char *s = NULL;
 268                 u64 val;
 269
 270                 /* flag not defined so don't check it */
 271                 if (flag->mask == 0)
 272                         continue;
 273                 /* Some 'flags' are actually values */
 274                 if (flag->is_val) {
 275                         val = pte & flag->val;
 276                         if (flag->shift)
 277                                 val = val >> flag->shift;
 278                         seq_printf(st->seq, "  %s:%llx", flag->set, val);
 279                 } else {
 280                         if ((pte & flag->mask) == flag->val)
 281                                 s = flag->set;
 282                         else
 283                                 s = flag->clear;
 284                         if (s)
 285                                 seq_printf(st->seq, "  %s", s);
 286                 }
 287                 st->current_flags &= ~flag->mask;
 288         }
 289         if (st->current_flags != 0)
 290                 seq_printf(st->seq, "  unknown flags:%llx", st->current_flags);
 291 }
 292
 293 static void dump_addr(struct pg_state *st, unsigned long addr)
 294 {
 295         static const char units[] = "KMGTPE";
 296         const char *unit = units;
 297         unsigned long delta;
 298
 299 #ifdef CONFIG_PPC64
 300         seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1);
 301         seq_printf(st->seq, "0x%016lx ", st->start_pa);
 302 #else
 303         seq_printf(st->seq, "0x%08lx-0x%08lx ", st->start_address, addr - 1);
 304         seq_printf(st->seq, "0x%08lx ", st->start_pa);
 305 #endif
 306
 307         delta = (addr - st->start_address) >> 10;
 308         /* Work out what appropriate unit to use */
 309         while (!(delta & 1023) && unit[1]) {
 310                 delta >>= 10;
 311                 unit++;
 312         }
 313         seq_printf(st->seq, "%9lu%c", delta, *unit);
 314
 315 }
 316
 317 static void note_page(struct pg_state *st, unsigned long addr,
 318                unsigned int level, u64 val)
 319 {
 320         u64 flag = val & pg_level[level].mask;
 321         u64 pa = val & PTE_RPN_MASK;
 322
 323         /* At first no level is set */
 324         if (!st->level) {
 325                 st->level = level;
 326                 st->current_flags = flag;
 327                 st->start_address = addr;
 328                 st->start_pa = pa;
 329                 st->last_pa = pa;
 330                 seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 331         /*
 332          * Dump the section of virtual memory when:
 333          *   - the PTE flags from one entry to the next differs.
 334          *   - we change levels in the tree.
 335          *   - the address is in a different section of memory and is thus
 336          *   used for a different purpose, regardless of the flags.
 337          *   - the pa of this page is not adjacent to the last inspected page
 338          */
 339         } else if (flag != st->current_flags || level != st->level ||
 340                    addr >= st->marker[1].start_address ||
 341                    pa != st->last_pa + PAGE_SIZE) {
 342
 343                 /* Check the PTE flags */
 344                 if (st->current_flags) {
 345                         dump_addr(st, addr);
 346
 347                         /* Dump all the flags */
 348                         if (pg_level[st->level].flag)
 349                                 dump_flag_info(st, pg_level[st->level].flag,
 350                                           st->current_flags,
 351                                           pg_level[st->level].num);
 352
 353                         seq_puts(st->seq, "\n");
 354                 }
 355
 356                 /*
 357                  * Address indicates we have passed the end of the
 358                  * current section of virtual memory
 359                  */
 360                 while (addr >= st->marker[1].start_address) {
 361                         st->marker++;
 362                         seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 363                 }
 364                 st->start_address = addr;
 365                 st->start_pa = pa;
 366                 st->last_pa = pa;
 367                 st->current_flags = flag;
 368                 st->level = level;
 369         } else {
 370                 st->last_pa = pa;
 371         }
 372 }
 373
 374 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
 375 {
 376         pte_t *pte = pte_offset_kernel(pmd, 0);
 377         unsigned long addr;
 378         unsigned int i;
 379
 380         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 381                 addr = start + i * PAGE_SIZE;
 382                 note_page(st, addr, 4, pte_val(*pte));
 383
 384         }
 385 }
 386
 387 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 388 {
 389         pmd_t *pmd = pmd_offset(pud, 0);
 390         unsigned long addr;
 391         unsigned int i;
 392
 393         for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 394                 addr = start + i * PMD_SIZE;
 395                 if (!pmd_none(*pmd) && !pmd_huge(*pmd))
 396                         /* pmd exists */
 397                         walk_pte(st, pmd, addr);
 398                 else
 399                         note_page(st, addr, 3, pmd_val(*pmd));
 400         }
 401 }
 402
 403 static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
 404 {
 405         pud_t *pud = pud_offset(pgd, 0);
 406         unsigned long addr;
 407         unsigned int i;
 408
 409         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 410                 addr = start + i * PUD_SIZE;
 411                 if (!pud_none(*pud) && !pud_huge(*pud))
 412                         /* pud exists */
 413                         walk_pmd(st, pud, addr);
 414                 else
 415                         note_page(st, addr, 2, pud_val(*pud));
 416         }
 417 }
 418
 419 static void walk_pagetables(struct pg_state *st)
 420 {
 421         pgd_t *pgd = pgd_offset_k(0UL);
 422         unsigned int i;
 423         unsigned long addr;
 424
 425         /*
 426          * Traverse the linux pagetable structure and dump pages that are in
 427          * the hash pagetable.
 428          */
 429         for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
 430                 addr = KERN_VIRT_START + i * PGDIR_SIZE;
 431                 if (!pgd_none(*pgd) && !pgd_huge(*pgd))
 432                         /* pgd exists */
 433                         walk_pud(st, pgd, addr);
 434                 else
 435                         note_page(st, addr, 1, pgd_val(*pgd));
 436         }
 437 }
 438
 439 static void populate_markers(void)
 440 {
 441         int i = 0;
 442
 443         address_markers[i++].start_address = PAGE_OFFSET;
 444         address_markers[i++].start_address = VMALLOC_START;
 445         address_markers[i++].start_address = VMALLOC_END;
 446 #ifdef CONFIG_PPC64
 447         address_markers[i++].start_address = ISA_IO_BASE;
 448         address_markers[i++].start_address = ISA_IO_END;
 449         address_markers[i++].start_address = PHB_IO_BASE;
 450         address_markers[i++].start_address = PHB_IO_END;
 451         address_markers[i++].start_address = IOREMAP_BASE;
 452         address_markers[i++].start_address = IOREMAP_END;
 453 #ifdef CONFIG_PPC_STD_MMU_64
 454         address_markers[i++].start_address =  H_VMEMMAP_BASE;
 455 #else
 456         address_markers[i++].start_address =  VMEMMAP_BASE;
 457 #endif
 458 #else /* !CONFIG_PPC64 */
 459         address_markers[i++].start_address = ioremap_bot;
 460         address_markers[i++].start_address = IOREMAP_TOP;
 461 #ifdef CONFIG_NOT_COHERENT_CACHE
 462         address_markers[i++].start_address = IOREMAP_TOP;
 463         address_markers[i++].start_address = IOREMAP_TOP +
 464                                              CONFIG_CONSISTENT_SIZE;
 465 #endif
 466 #ifdef CONFIG_HIGHMEM
 467         address_markers[i++].start_address = PKMAP_BASE;
 468         address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
 469 #endif
 470         address_markers[i++].start_address = FIXADDR_START;
 471         address_markers[i++].start_address = FIXADDR_TOP;
 472 #endif /* CONFIG_PPC64 */
 473 }
 474
 475 static int ptdump_show(struct seq_file *m, void *v)
 476 {
 477         struct pg_state st = {
 478                 .seq = m,
 479                 .start_address = KERN_VIRT_START,
 480                 .marker = address_markers,
 481         };
 482         /* Traverse kernel page tables */
 483         walk_pagetables(&st);
 484         note_page(&st, 0, 0, 0);
 485         return 0;
 486 }
 487
 488
 489 static int ptdump_open(struct inode *inode, struct file *file)
 490 {
 491         return single_open(file, ptdump_show, NULL);
 492 }
 493
 494 static const struct file_operations ptdump_fops = {
 495         .open           = ptdump_open,
 496         .read           = seq_read,
 497         .llseek         = seq_lseek,
 498         .release        = single_release,
 499 };
 500
 501 static void build_pgtable_complete_mask(void)
 502 {
 503         unsigned int i, j;
 504
 505         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 506                 if (pg_level[i].flag)
 507                         for (j = 0; j < pg_level[i].num; j++)
 508                                 pg_level[i].mask |= pg_level[i].flag[j].mask;
 509 }
 510
 511 static int ptdump_init(void)
 512 {
 513         struct dentry *debugfs_file;
 514
 515         populate_markers();
 516         build_pgtable_complete_mask();
 517         debugfs_file = debugfs_create_file("kernel_page_tables", 0400, NULL,
 518                         NULL, &ptdump_fops);
 519         return debugfs_file ? 0 : -ENOMEM;
 520 }
 521 device_initcall(ptdump_init);