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