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 #ifdef CONFIG_PPC_STD_MMU_64
 117                 .mask   = _PAGE_PRIVILEGED,
 118                 .val    = 0,
 119 #else
 120                 .mask   = _PAGE_USER,
 121                 .val    = _PAGE_USER,
 122 #endif
 123                 .set    = "user",
 124                 .clear  = "    ",
 125         }, {
 126 #if _PAGE_RO == 0
 127                 .mask   = _PAGE_RW,
 128                 .val    = _PAGE_RW,
 129 #else
 130                 .mask   = _PAGE_RO,
 131                 .val    = 0,
 132 #endif
 133                 .set    = "rw",
 134                 .clear  = "ro",
 135         }, {
 136                 .mask   = _PAGE_EXEC,
 137                 .val    = _PAGE_EXEC,
 138                 .set    = " X ",
 139                 .clear  = "   ",
 140         }, {
 141                 .mask   = _PAGE_PTE,
 142                 .val    = _PAGE_PTE,
 143                 .set    = "pte",
 144                 .clear  = "   ",
 145         }, {
 146                 .mask   = _PAGE_PRESENT,
 147                 .val    = _PAGE_PRESENT,
 148                 .set    = "present",
 149                 .clear  = "       ",
 150         }, {
 151 #ifdef CONFIG_PPC_STD_MMU_64
 152                 .mask   = H_PAGE_HASHPTE,
 153                 .val    = H_PAGE_HASHPTE,
 154 #else
 155                 .mask   = _PAGE_HASHPTE,
 156                 .val    = _PAGE_HASHPTE,
 157 #endif
 158                 .set    = "hpte",
 159                 .clear  = "    ",
 160         }, {
 161 #ifndef CONFIG_PPC_STD_MMU_64
 162                 .mask   = _PAGE_GUARDED,
 163                 .val    = _PAGE_GUARDED,
 164                 .set    = "guarded",
 165                 .clear  = "       ",
 166         }, {
 167 #endif
 168                 .mask   = _PAGE_DIRTY,
 169                 .val    = _PAGE_DIRTY,
 170                 .set    = "dirty",
 171                 .clear  = "     ",
 172         }, {
 173                 .mask   = _PAGE_ACCESSED,
 174                 .val    = _PAGE_ACCESSED,
 175                 .set    = "accessed",
 176                 .clear  = "        ",
 177         }, {
 178 #ifndef CONFIG_PPC_STD_MMU_64
 179                 .mask   = _PAGE_WRITETHRU,
 180                 .val    = _PAGE_WRITETHRU,
 181                 .set    = "write through",
 182                 .clear  = "             ",
 183         }, {
 184 #endif
 185 #ifndef CONFIG_PPC_BOOK3S_64
 186                 .mask   = _PAGE_NO_CACHE,
 187                 .val    = _PAGE_NO_CACHE,
 188                 .set    = "no cache",
 189                 .clear  = "        ",
 190         }, {
 191 #else
 192                 .mask   = _PAGE_NON_IDEMPOTENT,
 193                 .val    = _PAGE_NON_IDEMPOTENT,
 194                 .set    = "non-idempotent",
 195                 .clear  = "              ",
 196         }, {
 197                 .mask   = _PAGE_TOLERANT,
 198                 .val    = _PAGE_TOLERANT,
 199                 .set    = "tolerant",
 200                 .clear  = "        ",
 201         }, {
 202 #endif
 203 #ifdef CONFIG_PPC_BOOK3S_64
 204                 .mask   = H_PAGE_BUSY,
 205                 .val    = H_PAGE_BUSY,
 206                 .set    = "busy",
 207         }, {
 208 #ifdef CONFIG_PPC_64K_PAGES
 209                 .mask   = H_PAGE_COMBO,
 210                 .val    = H_PAGE_COMBO,
 211                 .set    = "combo",
 212         }, {
 213                 .mask   = H_PAGE_4K_PFN,
 214                 .val    = H_PAGE_4K_PFN,
 215                 .set    = "4K_pfn",
 216         }, {
 217 #endif
 218                 .mask   = H_PAGE_F_GIX,
 219                 .val    = H_PAGE_F_GIX,
 220                 .set    = "f_gix",
 221                 .is_val = true,
 222                 .shift  = H_PAGE_F_GIX_SHIFT,
 223         }, {
 224                 .mask   = H_PAGE_F_SECOND,
 225                 .val    = H_PAGE_F_SECOND,
 226                 .set    = "f_second",
 227         }, {
 228 #endif
 229                 .mask   = _PAGE_SPECIAL,
 230                 .val    = _PAGE_SPECIAL,
 231                 .set    = "special",
 232         }, {
 233                 .mask   = _PAGE_SHARED,
 234                 .val    = _PAGE_SHARED,
 235                 .set    = "shared",
 236         }
 237 };
 238
 239 struct pgtable_level {
 240         const struct flag_info *flag;
 241         size_t num;
 242         u64 mask;
 243 };
 244
 245 static struct pgtable_level pg_level[] = {
 246         {
 247         }, { /* pgd */
 248                 .flag   = flag_array,
 249                 .num    = ARRAY_SIZE(flag_array),
 250         }, { /* pud */
 251                 .flag   = flag_array,
 252                 .num    = ARRAY_SIZE(flag_array),
 253         }, { /* pmd */
 254                 .flag   = flag_array,
 255                 .num    = ARRAY_SIZE(flag_array),
 256         }, { /* pte */
 257                 .flag   = flag_array,
 258                 .num    = ARRAY_SIZE(flag_array),
 259         },
 260 };
 261
 262 static void dump_flag_info(struct pg_state *st, const struct flag_info
 263                 *flag, u64 pte, int num)
 264 {
 265         unsigned int i;
 266
 267         for (i = 0; i < num; i++, flag++) {
 268                 const char *s = NULL;
 269                 u64 val;
 270
 271                 /* flag not defined so don't check it */
 272                 if (flag->mask == 0)
 273                         continue;
 274                 /* Some 'flags' are actually values */
 275                 if (flag->is_val) {
 276                         val = pte & flag->val;
 277                         if (flag->shift)
 278                                 val = val >> flag->shift;
 279                         seq_printf(st->seq, "  %s:%llx", flag->set, val);
 280                 } else {
 281                         if ((pte & flag->mask) == flag->val)
 282                                 s = flag->set;
 283                         else
 284                                 s = flag->clear;
 285                         if (s)
 286                                 seq_printf(st->seq, "  %s", s);
 287                 }
 288                 st->current_flags &= ~flag->mask;
 289         }
 290         if (st->current_flags != 0)
 291                 seq_printf(st->seq, "  unknown flags:%llx", st->current_flags);
 292 }
 293
 294 static void dump_addr(struct pg_state *st, unsigned long addr)
 295 {
 296         static const char units[] = "KMGTPE";
 297         const char *unit = units;
 298         unsigned long delta;
 299
 300 #ifdef CONFIG_PPC64
 301         seq_printf(st->seq, "0x%016lx-0x%016lx ", st->start_address, addr-1);
 302         seq_printf(st->seq, "0x%016lx ", st->start_pa);
 303 #else
 304         seq_printf(st->seq, "0x%08lx-0x%08lx ", st->start_address, addr - 1);
 305         seq_printf(st->seq, "0x%08lx ", st->start_pa);
 306 #endif
 307
 308         delta = (addr - st->start_address) >> 10;
 309         /* Work out what appropriate unit to use */
 310         while (!(delta & 1023) && unit[1]) {
 311                 delta >>= 10;
 312                 unit++;
 313         }
 314         seq_printf(st->seq, "%9lu%c", delta, *unit);
 315
 316 }
 317
 318 static void note_page(struct pg_state *st, unsigned long addr,
 319                unsigned int level, u64 val)
 320 {
 321         u64 flag = val & pg_level[level].mask;
 322         u64 pa = val & PTE_RPN_MASK;
 323
 324         /* At first no level is set */
 325         if (!st->level) {
 326                 st->level = level;
 327                 st->current_flags = flag;
 328                 st->start_address = addr;
 329                 st->start_pa = pa;
 330                 st->last_pa = pa;
 331                 seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 332         /*
 333          * Dump the section of virtual memory when:
 334          *   - the PTE flags from one entry to the next differs.
 335          *   - we change levels in the tree.
 336          *   - the address is in a different section of memory and is thus
 337          *   used for a different purpose, regardless of the flags.
 338          *   - the pa of this page is not adjacent to the last inspected page
 339          */
 340         } else if (flag != st->current_flags || level != st->level ||
 341                    addr >= st->marker[1].start_address ||
 342                    pa != st->last_pa + PAGE_SIZE) {
 343
 344                 /* Check the PTE flags */
 345                 if (st->current_flags) {
 346                         dump_addr(st, addr);
 347
 348                         /* Dump all the flags */
 349                         if (pg_level[st->level].flag)
 350                                 dump_flag_info(st, pg_level[st->level].flag,
 351                                           st->current_flags,
 352                                           pg_level[st->level].num);
 353
 354                         seq_putc(st->seq, '\n');
 355                 }
 356
 357                 /*
 358                  * Address indicates we have passed the end of the
 359                  * current section of virtual memory
 360                  */
 361                 while (addr >= st->marker[1].start_address) {
 362                         st->marker++;
 363                         seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 364                 }
 365                 st->start_address = addr;
 366                 st->start_pa = pa;
 367                 st->last_pa = pa;
 368                 st->current_flags = flag;
 369                 st->level = level;
 370         } else {
 371                 st->last_pa = pa;
 372         }
 373 }
 374
 375 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
 376 {
 377         pte_t *pte = pte_offset_kernel(pmd, 0);
 378         unsigned long addr;
 379         unsigned int i;
 380
 381         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 382                 addr = start + i * PAGE_SIZE;
 383                 note_page(st, addr, 4, pte_val(*pte));
 384
 385         }
 386 }
 387
 388 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 389 {
 390         pmd_t *pmd = pmd_offset(pud, 0);
 391         unsigned long addr;
 392         unsigned int i;
 393
 394         for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 395                 addr = start + i * PMD_SIZE;
 396                 if (!pmd_none(*pmd) && !pmd_huge(*pmd))
 397                         /* pmd exists */
 398                         walk_pte(st, pmd, addr);
 399                 else
 400                         note_page(st, addr, 3, pmd_val(*pmd));
 401         }
 402 }
 403
 404 static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
 405 {
 406         pud_t *pud = pud_offset(pgd, 0);
 407         unsigned long addr;
 408         unsigned int i;
 409
 410         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 411                 addr = start + i * PUD_SIZE;
 412                 if (!pud_none(*pud) && !pud_huge(*pud))
 413                         /* pud exists */
 414                         walk_pmd(st, pud, addr);
 415                 else
 416                         note_page(st, addr, 2, pud_val(*pud));
 417         }
 418 }
 419
 420 static void walk_pagetables(struct pg_state *st)
 421 {
 422         pgd_t *pgd = pgd_offset_k(0UL);
 423         unsigned int i;
 424         unsigned long addr;
 425
 426         addr = st->start_address;
 427
 428         /*
 429          * Traverse the linux pagetable structure and dump pages that are in
 430          * the hash pagetable.
 431          */
 432         for (i = 0; i < PTRS_PER_PGD; i++, pgd++, addr += PGDIR_SIZE) {
 433                 if (!pgd_none(*pgd) && !pgd_huge(*pgd))
 434                         /* pgd exists */
 435                         walk_pud(st, pgd, addr);
 436                 else
 437                         note_page(st, addr, 1, pgd_val(*pgd));
 438         }
 439 }
 440
 441 static void populate_markers(void)
 442 {
 443         int i = 0;
 444
 445         address_markers[i++].start_address = PAGE_OFFSET;
 446         address_markers[i++].start_address = VMALLOC_START;
 447         address_markers[i++].start_address = VMALLOC_END;
 448 #ifdef CONFIG_PPC64
 449         address_markers[i++].start_address = ISA_IO_BASE;
 450         address_markers[i++].start_address = ISA_IO_END;
 451         address_markers[i++].start_address = PHB_IO_BASE;
 452         address_markers[i++].start_address = PHB_IO_END;
 453         address_markers[i++].start_address = IOREMAP_BASE;
 454         address_markers[i++].start_address = IOREMAP_END;
 455 #ifdef CONFIG_PPC_STD_MMU_64
 456         address_markers[i++].start_address =  H_VMEMMAP_BASE;
 457 #else
 458         address_markers[i++].start_address =  VMEMMAP_BASE;
 459 #endif
 460 #else /* !CONFIG_PPC64 */
 461         address_markers[i++].start_address = ioremap_bot;
 462         address_markers[i++].start_address = IOREMAP_TOP;
 463 #ifdef CONFIG_NOT_COHERENT_CACHE
 464         address_markers[i++].start_address = IOREMAP_TOP;
 465         address_markers[i++].start_address = IOREMAP_TOP +
 466                                              CONFIG_CONSISTENT_SIZE;
 467 #endif
 468 #ifdef CONFIG_HIGHMEM
 469         address_markers[i++].start_address = PKMAP_BASE;
 470         address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
 471 #endif
 472         address_markers[i++].start_address = FIXADDR_START;
 473         address_markers[i++].start_address = FIXADDR_TOP;
 474 #endif /* CONFIG_PPC64 */
 475 }
 476
 477 static int ptdump_show(struct seq_file *m, void *v)
 478 {
 479         struct pg_state st = {
 480                 .seq = m,
 481                 .marker = address_markers,
 482         };
 483
 484         if (radix_enabled())
 485                 st.start_address = PAGE_OFFSET;
 486         else
 487                 st.start_address = KERN_VIRT_START;
 488
 489         /* Traverse kernel page tables */
 490         walk_pagetables(&st);
 491         note_page(&st, 0, 0, 0);
 492         return 0;
 493 }
 494
 495
 496 static int ptdump_open(struct inode *inode, struct file *file)
 497 {
 498         return single_open(file, ptdump_show, NULL);
 499 }
 500
 501 static const struct file_operations ptdump_fops = {
 502         .open           = ptdump_open,
 503         .read           = seq_read,
 504         .llseek         = seq_lseek,
 505         .release        = single_release,
 506 };
 507
 508 static void build_pgtable_complete_mask(void)
 509 {
 510         unsigned int i, j;
 511
 512         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 513                 if (pg_level[i].flag)
 514                         for (j = 0; j < pg_level[i].num; j++)
 515                                 pg_level[i].mask |= pg_level[i].flag[j].mask;
 516 }
 517
 518 static int ptdump_init(void)
 519 {
 520         struct dentry *debugfs_file;
 521
 522         populate_markers();
 523         build_pgtable_complete_mask();
 524         debugfs_file = debugfs_create_file("kernel_page_tables", 0400, NULL,
 525                         NULL, &ptdump_fops);
 526         return debugfs_file ? 0 : -ENOMEM;
 527 }
 528 device_initcall(ptdump_init);