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/highmem.h>
  23 #include <linux/sched.h>
  24 #include <linux/seq_file.h>
  25 #include <asm/fixmap.h>
  26 #include <asm/pgtable.h>
  27 #include <linux/const.h>
  28 #include <asm/page.h>
  29 #include <asm/pgalloc.h>
  30
  31 #ifdef CONFIG_PPC32
  32 #define KERN_VIRT_START 0
  33 #endif
  34
  35 /*
  36  * To visualise what is happening,
  37  *
  38  *  - PTRS_PER_P** = how many entries there are in the corresponding P**
  39  *  - P**_SHIFT = how many bits of the address we use to index into the
  40  * corresponding P**
  41  *  - P**_SIZE is how much memory we can access through the table - not the
  42  * size of the table itself.
  43  * P**={PGD, PUD, PMD, PTE}
  44  *
  45  *
  46  * Each entry of the PGD points to a PUD. Each entry of a PUD points to a
  47  * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to
  48  * a page.
  49  *
  50  * In the case where there are only 3 levels, the PUD is folded into the
  51  * PGD: every PUD has only one entry which points to the PMD.
  52  *
  53  * The page dumper groups page table entries of the same type into a single
  54  * description. It uses pg_state to track the range information while
  55  * iterating over the PTE entries. When the continuity is broken it then
  56  * dumps out a description of the range - ie PTEs that are virtually contiguous
  57  * with the same PTE flags are chunked together. This is to make it clear how
  58  * different areas of the kernel virtual memory are used.
  59  *
  60  */
  61 struct pg_state {
  62         struct seq_file *seq;
  63         const struct addr_marker *marker;
  64         unsigned long start_address;
  65         unsigned long start_pa;
  66         unsigned long last_pa;
  67         unsigned int level;
  68         u64 current_flags;
  69 };
  70
  71 struct addr_marker {
  72         unsigned long start_address;
  73         const char *name;
  74 };
  75
  76 static struct addr_marker address_markers[] = {
  77         { 0,    "Start of kernel VM" },
  78         { 0,    "vmalloc() Area" },
  79         { 0,    "vmalloc() End" },
  80 #ifdef CONFIG_PPC64
  81         { 0,    "isa I/O start" },
  82         { 0,    "isa I/O end" },
  83         { 0,    "phb I/O start" },
  84         { 0,    "phb I/O end" },
  85         { 0,    "I/O remap start" },
  86         { 0,    "I/O remap end" },
  87         { 0,    "vmemmap start" },
  88 #else
  89         { 0,    "Early I/O remap start" },
  90         { 0,    "Early I/O remap end" },
  91 #ifdef CONFIG_NOT_COHERENT_CACHE
  92         { 0,    "Consistent mem start" },
  93         { 0,    "Consistent mem end" },
  94 #endif
  95 #ifdef CONFIG_HIGHMEM
  96         { 0,    "Highmem PTEs start" },
  97         { 0,    "Highmem PTEs end" },
  98 #endif
  99         { 0,    "Fixmap start" },
 100         { 0,    "Fixmap end" },
 101 #endif
 102         { -1,   NULL },
 103 };
 104
 105 struct flag_info {
 106         u64             mask;
 107         u64             val;
 108         const char      *set;
 109         const char      *clear;
 110         bool            is_val;
 111         int             shift;
 112 };
 113
 114 static const struct flag_info flag_array[] = {
 115         {
 116                 .mask   = _PAGE_USER | _PAGE_PRIVILEGED,
 117                 .val    = _PAGE_USER,
 118                 .set    = "user",
 119                 .clear  = "    ",
 120         }, {
 121                 .mask   = _PAGE_RW | _PAGE_RO | _PAGE_NA,
 122                 .val    = _PAGE_RW,
 123                 .set    = "rw",
 124         }, {
 125                 .mask   = _PAGE_RW | _PAGE_RO | _PAGE_NA,
 126                 .val    = _PAGE_RO,
 127                 .set    = "ro",
 128         }, {
 129 #if _PAGE_NA != 0
 130                 .mask   = _PAGE_RW | _PAGE_RO | _PAGE_NA,
 131                 .val    = _PAGE_RO,
 132                 .set    = "na",
 133         }, {
 134 #endif
 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_BOOK3S_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_BOOK3S_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_BOOK3S_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 #else /* CONFIG_PPC_64K_PAGES */
 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 /* CONFIG_PPC_64K_PAGES */
 228 #endif
 229                 .mask   = _PAGE_SPECIAL,
 230                 .val    = _PAGE_SPECIAL,
 231                 .set    = "special",
 232         }
 233 };
 234
 235 struct pgtable_level {
 236         const struct flag_info *flag;
 237         size_t num;
 238         u64 mask;
 239 };
 240
 241 static struct pgtable_level pg_level[] = {
 242         {
 243         }, { /* pgd */
 244                 .flag   = flag_array,
 245                 .num    = ARRAY_SIZE(flag_array),
 246         }, { /* pud */
 247                 .flag   = flag_array,
 248                 .num    = ARRAY_SIZE(flag_array),
 249         }, { /* pmd */
 250                 .flag   = flag_array,
 251                 .num    = ARRAY_SIZE(flag_array),
 252         }, { /* pte */
 253                 .flag   = flag_array,
 254                 .num    = ARRAY_SIZE(flag_array),
 255         },
 256 };
 257
 258 static void dump_flag_info(struct pg_state *st, const struct flag_info
 259                 *flag, u64 pte, int num)
 260 {
 261         unsigned int i;
 262
 263         for (i = 0; i < num; i++, flag++) {
 264                 const char *s = NULL;
 265                 u64 val;
 266
 267                 /* flag not defined so don't check it */
 268                 if (flag->mask == 0)
 269                         continue;
 270                 /* Some 'flags' are actually values */
 271                 if (flag->is_val) {
 272                         val = pte & flag->val;
 273                         if (flag->shift)
 274                                 val = val >> flag->shift;
 275                         seq_printf(st->seq, "  %s:%llx", flag->set, val);
 276                 } else {
 277                         if ((pte & flag->mask) == flag->val)
 278                                 s = flag->set;
 279                         else
 280                                 s = flag->clear;
 281                         if (s)
 282                                 seq_printf(st->seq, "  %s", s);
 283                 }
 284                 st->current_flags &= ~flag->mask;
 285         }
 286         if (st->current_flags != 0)
 287                 seq_printf(st->seq, "  unknown flags:%llx", st->current_flags);
 288 }
 289
 290 static void dump_addr(struct pg_state *st, unsigned long addr)
 291 {
 292         static const char units[] = "KMGTPE";
 293         const char *unit = units;
 294         unsigned long delta;
 295
 296 #ifdef CONFIG_PPC64
 297         seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1);
 298         seq_printf(st->seq, "0x%016lx ", st->start_pa);
 299 #else
 300         seq_printf(st->seq, "0x%08lx-0x%08lx ", st->start_address, addr - 1);
 301         seq_printf(st->seq, "0x%08lx ", st->start_pa);
 302 #endif
 303
 304         delta = (addr - st->start_address) >> 10;
 305         /* Work out what appropriate unit to use */
 306         while (!(delta & 1023) && unit[1]) {
 307                 delta >>= 10;
 308                 unit++;
 309         }
 310         seq_printf(st->seq, "%9lu%c", delta, *unit);
 311
 312 }
 313
 314 static void note_page(struct pg_state *st, unsigned long addr,
 315                unsigned int level, u64 val)
 316 {
 317         u64 flag = val & pg_level[level].mask;
 318         u64 pa = val & PTE_RPN_MASK;
 319
 320         /* At first no level is set */
 321         if (!st->level) {
 322                 st->level = level;
 323                 st->current_flags = flag;
 324                 st->start_address = addr;
 325                 st->start_pa = pa;
 326                 st->last_pa = pa;
 327                 seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 328         /*
 329          * Dump the section of virtual memory when:
 330          *   - the PTE flags from one entry to the next differs.
 331          *   - we change levels in the tree.
 332          *   - the address is in a different section of memory and is thus
 333          *   used for a different purpose, regardless of the flags.
 334          *   - the pa of this page is not adjacent to the last inspected page
 335          */
 336         } else if (flag != st->current_flags || level != st->level ||
 337                    addr >= st->marker[1].start_address ||
 338                    pa != st->last_pa + PAGE_SIZE) {
 339
 340                 /* Check the PTE flags */
 341                 if (st->current_flags) {
 342                         dump_addr(st, addr);
 343
 344                         /* Dump all the flags */
 345                         if (pg_level[st->level].flag)
 346                                 dump_flag_info(st, pg_level[st->level].flag,
 347                                           st->current_flags,
 348                                           pg_level[st->level].num);
 349
 350                         seq_putc(st->seq, '\n');
 351                 }
 352
 353                 /*
 354                  * Address indicates we have passed the end of the
 355                  * current section of virtual memory
 356                  */
 357                 while (addr >= st->marker[1].start_address) {
 358                         st->marker++;
 359                         seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 360                 }
 361                 st->start_address = addr;
 362                 st->start_pa = pa;
 363                 st->last_pa = pa;
 364                 st->current_flags = flag;
 365                 st->level = level;
 366         } else {
 367                 st->last_pa = pa;
 368         }
 369 }
 370
 371 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
 372 {
 373         pte_t *pte = pte_offset_kernel(pmd, 0);
 374         unsigned long addr;
 375         unsigned int i;
 376
 377         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 378                 addr = start + i * PAGE_SIZE;
 379                 note_page(st, addr, 4, pte_val(*pte));
 380
 381         }
 382 }
 383
 384 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 385 {
 386         pmd_t *pmd = pmd_offset(pud, 0);
 387         unsigned long addr;
 388         unsigned int i;
 389
 390         for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 391                 addr = start + i * PMD_SIZE;
 392                 if (!pmd_none(*pmd) && !pmd_huge(*pmd))
 393                         /* pmd exists */
 394                         walk_pte(st, pmd, addr);
 395                 else
 396                         note_page(st, addr, 3, pmd_val(*pmd));
 397         }
 398 }
 399
 400 static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
 401 {
 402         pud_t *pud = pud_offset(pgd, 0);
 403         unsigned long addr;
 404         unsigned int i;
 405
 406         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 407                 addr = start + i * PUD_SIZE;
 408                 if (!pud_none(*pud) && !pud_huge(*pud))
 409                         /* pud exists */
 410                         walk_pmd(st, pud, addr);
 411                 else
 412                         note_page(st, addr, 2, pud_val(*pud));
 413         }
 414 }
 415
 416 static void walk_pagetables(struct pg_state *st)
 417 {
 418         pgd_t *pgd = pgd_offset_k(0UL);
 419         unsigned int i;
 420         unsigned long addr;
 421
 422         addr = st->start_address;
 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++, addr += PGDIR_SIZE) {
 429                 if (!pgd_none(*pgd) && !pgd_huge(*pgd))
 430                         /* pgd exists */
 431                         walk_pud(st, pgd, addr);
 432                 else
 433                         note_page(st, addr, 1, pgd_val(*pgd));
 434         }
 435 }
 436
 437 static void populate_markers(void)
 438 {
 439         int i = 0;
 440
 441         address_markers[i++].start_address = PAGE_OFFSET;
 442         address_markers[i++].start_address = VMALLOC_START;
 443         address_markers[i++].start_address = VMALLOC_END;
 444 #ifdef CONFIG_PPC64
 445         address_markers[i++].start_address = ISA_IO_BASE;
 446         address_markers[i++].start_address = ISA_IO_END;
 447         address_markers[i++].start_address = PHB_IO_BASE;
 448         address_markers[i++].start_address = PHB_IO_END;
 449         address_markers[i++].start_address = IOREMAP_BASE;
 450         address_markers[i++].start_address = IOREMAP_END;
 451 #ifdef CONFIG_PPC_BOOK3S_64
 452         address_markers[i++].start_address =  H_VMEMMAP_BASE;
 453 #else
 454         address_markers[i++].start_address =  VMEMMAP_BASE;
 455 #endif
 456 #else /* !CONFIG_PPC64 */
 457         address_markers[i++].start_address = ioremap_bot;
 458         address_markers[i++].start_address = IOREMAP_TOP;
 459 #ifdef CONFIG_NOT_COHERENT_CACHE
 460         address_markers[i++].start_address = IOREMAP_TOP;
 461         address_markers[i++].start_address = IOREMAP_TOP +
 462                                              CONFIG_CONSISTENT_SIZE;
 463 #endif
 464 #ifdef CONFIG_HIGHMEM
 465         address_markers[i++].start_address = PKMAP_BASE;
 466         address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
 467 #endif
 468         address_markers[i++].start_address = FIXADDR_START;
 469         address_markers[i++].start_address = FIXADDR_TOP;
 470 #endif /* CONFIG_PPC64 */
 471 }
 472
 473 static int ptdump_show(struct seq_file *m, void *v)
 474 {
 475         struct pg_state st = {
 476                 .seq = m,
 477                 .marker = address_markers,
 478         };
 479
 480         if (radix_enabled())
 481                 st.start_address = PAGE_OFFSET;
 482         else
 483                 st.start_address = KERN_VIRT_START;
 484
 485         /* Traverse kernel page tables */
 486         walk_pagetables(&st);
 487         note_page(&st, 0, 0, 0);
 488         return 0;
 489 }
 490
 491
 492 static int ptdump_open(struct inode *inode, struct file *file)
 493 {
 494         return single_open(file, ptdump_show, NULL);
 495 }
 496
 497 static const struct file_operations ptdump_fops = {
 498         .open           = ptdump_open,
 499         .read           = seq_read,
 500         .llseek         = seq_lseek,
 501         .release        = single_release,
 502 };
 503
 504 static void build_pgtable_complete_mask(void)
 505 {
 506         unsigned int i, j;
 507
 508         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 509                 if (pg_level[i].flag)
 510                         for (j = 0; j < pg_level[i].num; j++)
 511                                 pg_level[i].mask |= pg_level[i].flag[j].mask;
 512 }
 513
 514 static int ptdump_init(void)
 515 {
 516         struct dentry *debugfs_file;
 517
 518         populate_markers();
 519         build_pgtable_complete_mask();
 520         debugfs_file = debugfs_create_file("kernel_page_tables", 0400, NULL,
 521                         NULL, &ptdump_fops);
 522         return debugfs_file ? 0 : -ENOMEM;
 523 }
 524 device_initcall(ptdump_init);