arch/arm/mm/dump.c

   1 /*
   2  * Debug helper to dump the current kernel pagetables of the system
   3  * so that we can see what the various memory ranges are set to.
   4  *
   5  * Derived from x86 implementation:
   6  * (C) Copyright 2008 Intel Corporation
   7  *
   8  * Author: Arjan van de Ven <arjan@linux.intel.com>
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; version 2
  13  * of the License.
  14  */
  15 #include <linux/debugfs.h>
  16 #include <linux/fs.h>
  17 #include <linux/mm.h>
  18 #include <linux/seq_file.h>
  19
  20 #include <asm/fixmap.h>
  21 #include <asm/pgtable.h>
  22
  23 struct addr_marker {
  24         unsigned long start_address;
  25         const char *name;
  26 };
  27
  28 static struct addr_marker address_markers[] = {
  29         { MODULES_VADDR,        "Modules" },
  30         { PAGE_OFFSET,          "Kernel Mapping" },
  31         { 0,                    "vmalloc() Area" },
  32         { VMALLOC_END,          "vmalloc() End" },
  33         { FIXADDR_START,        "Fixmap Area" },
  34         { CONFIG_VECTORS_BASE,  "Vectors" },
  35         { CONFIG_VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" },
  36         { -1,                   NULL },
  37 };
  38
  39 struct pg_state {
  40         struct seq_file *seq;
  41         const struct addr_marker *marker;
  42         unsigned long start_address;
  43         unsigned level;
  44         u64 current_prot;
  45 };
  46
  47 struct prot_bits {
  48         u64             mask;
  49         u64             val;
  50         const char      *set;
  51         const char      *clear;
  52 };
  53
  54 static const struct prot_bits pte_bits[] = {
  55         {
  56                 .mask   = L_PTE_USER,
  57                 .val    = L_PTE_USER,
  58                 .set    = "USR",
  59                 .clear  = "   ",
  60         }, {
  61                 .mask   = L_PTE_RDONLY,
  62                 .val    = L_PTE_RDONLY,
  63                 .set    = "ro",
  64                 .clear  = "RW",
  65         }, {
  66                 .mask   = L_PTE_XN,
  67                 .val    = L_PTE_XN,
  68                 .set    = "NX",
  69                 .clear  = "x ",
  70         }, {
  71                 .mask   = L_PTE_SHARED,
  72                 .val    = L_PTE_SHARED,
  73                 .set    = "SHD",
  74                 .clear  = "   ",
  75         }, {
  76                 .mask   = L_PTE_MT_MASK,
  77                 .val    = L_PTE_MT_UNCACHED,
  78                 .set    = "SO/UNCACHED",
  79         }, {
  80                 .mask   = L_PTE_MT_MASK,
  81                 .val    = L_PTE_MT_BUFFERABLE,
  82                 .set    = "MEM/BUFFERABLE/WC",
  83         }, {
  84                 .mask   = L_PTE_MT_MASK,
  85                 .val    = L_PTE_MT_WRITETHROUGH,
  86                 .set    = "MEM/CACHED/WT",
  87         }, {
  88                 .mask   = L_PTE_MT_MASK,
  89                 .val    = L_PTE_MT_WRITEBACK,
  90                 .set    = "MEM/CACHED/WBRA",
  91 #ifndef CONFIG_ARM_LPAE
  92         }, {
  93                 .mask   = L_PTE_MT_MASK,
  94                 .val    = L_PTE_MT_MINICACHE,
  95                 .set    = "MEM/MINICACHE",
  96 #endif
  97         }, {
  98                 .mask   = L_PTE_MT_MASK,
  99                 .val    = L_PTE_MT_WRITEALLOC,
 100                 .set    = "MEM/CACHED/WBWA",
 101         }, {
 102                 .mask   = L_PTE_MT_MASK,
 103                 .val    = L_PTE_MT_DEV_SHARED,
 104                 .set    = "DEV/SHARED",
 105 #ifndef CONFIG_ARM_LPAE
 106         }, {
 107                 .mask   = L_PTE_MT_MASK,
 108                 .val    = L_PTE_MT_DEV_NONSHARED,
 109                 .set    = "DEV/NONSHARED",
 110 #endif
 111         }, {
 112                 .mask   = L_PTE_MT_MASK,
 113                 .val    = L_PTE_MT_DEV_WC,
 114                 .set    = "DEV/WC",
 115         }, {
 116                 .mask   = L_PTE_MT_MASK,
 117                 .val    = L_PTE_MT_DEV_CACHED,
 118                 .set    = "DEV/CACHED",
 119         },
 120 };
 121
 122 static const struct prot_bits section_bits[] = {
 123 #ifndef CONFIG_ARM_LPAE
 124         /* These are approximate */
 125         {
 126                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 127                 .val    = 0,
 128                 .set    = "    ro",
 129         }, {
 130                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 131                 .val    = PMD_SECT_AP_WRITE,
 132                 .set    = "    RW",
 133         }, {
 134                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 135                 .val    = PMD_SECT_AP_READ,
 136                 .set    = "USR ro",
 137         }, {
 138                 .mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 139                 .val    = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
 140                 .set    = "USR RW",
 141 #else
 142         {
 143                 .mask   = PMD_SECT_USER,
 144                 .val    = PMD_SECT_USER,
 145                 .set    = "USR",
 146         }, {
 147                 .mask   = PMD_SECT_RDONLY,
 148                 .val    = PMD_SECT_RDONLY,
 149                 .set    = "ro",
 150                 .clear  = "RW",
 151 #endif
 152         }, {
 153                 .mask   = PMD_SECT_XN,
 154                 .val    = PMD_SECT_XN,
 155                 .set    = "NX",
 156                 .clear  = "x ",
 157         }, {
 158                 .mask   = PMD_SECT_S,
 159                 .val    = PMD_SECT_S,
 160                 .set    = "SHD",
 161                 .clear  = "   ",
 162         },
 163 };
 164
 165 struct pg_level {
 166         const struct prot_bits *bits;
 167         size_t num;
 168         u64 mask;
 169 };
 170
 171 static struct pg_level pg_level[] = {
 172         {
 173         }, { /* pgd */
 174         }, { /* pud */
 175         }, { /* pmd */
 176                 .bits   = section_bits,
 177                 .num    = ARRAY_SIZE(section_bits),
 178         }, { /* pte */
 179                 .bits   = pte_bits,
 180                 .num    = ARRAY_SIZE(pte_bits),
 181         },
 182 };
 183
 184 static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t num)
 185 {
 186         unsigned i;
 187
 188         for (i = 0; i < num; i++, bits++) {
 189                 const char *s;
 190
 191                 if ((st->current_prot & bits->mask) == bits->val)
 192                         s = bits->set;
 193                 else
 194                         s = bits->clear;
 195
 196                 if (s)
 197                         seq_printf(st->seq, " %s", s);
 198         }
 199 }
 200
 201 static void note_page(struct pg_state *st, unsigned long addr, unsigned level, u64 val)
 202 {
 203         static const char units[] = "KMGTPE";
 204         u64 prot = val & pg_level[level].mask;
 205
 206         if (addr < USER_PGTABLES_CEILING)
 207                 return;
 208
 209         if (!st->level) {
 210                 st->level = level;
 211                 st->current_prot = prot;
 212                 seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 213         } else if (prot != st->current_prot || level != st->level ||
 214                    addr >= st->marker[1].start_address) {
 215                 const char *unit = units;
 216                 unsigned long delta;
 217
 218                 if (st->current_prot) {
 219                         seq_printf(st->seq, "0x%08lx-0x%08lx   ",
 220                                    st->start_address, addr);
 221
 222                         delta = (addr - st->start_address) >> 10;
 223                         while (!(delta & 1023) && unit[1]) {
 224                                 delta >>= 10;
 225                                 unit++;
 226                         }
 227                         seq_printf(st->seq, "%9lu%c", delta, *unit);
 228                         if (pg_level[st->level].bits)
 229                                 dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num);
 230                         seq_printf(st->seq, "\n");
 231                 }
 232
 233                 if (addr >= st->marker[1].start_address) {
 234                         st->marker++;
 235                         seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 236                 }
 237                 st->start_address = addr;
 238                 st->current_prot = prot;
 239                 st->level = level;
 240         }
 241 }
 242
 243 static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
 244 {
 245         pte_t *pte = pte_offset_kernel(pmd, 0);
 246         unsigned long addr;
 247         unsigned i;
 248
 249         for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
 250                 addr = start + i * PAGE_SIZE;
 251                 note_page(st, addr, 4, pte_val(*pte));
 252         }
 253 }
 254
 255 static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
 256 {
 257         pmd_t *pmd = pmd_offset(pud, 0);
 258         unsigned long addr;
 259         unsigned i;
 260
 261         for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
 262                 addr = start + i * PMD_SIZE;
 263                 if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd))
 264                         note_page(st, addr, 3, pmd_val(*pmd));
 265                 else
 266                         walk_pte(st, pmd, addr);
 267
 268                 if (SECTION_SIZE < PMD_SIZE && pmd_large(pmd[1]))
 269                         note_page(st, addr + SECTION_SIZE, 3, pmd_val(pmd[1]));
 270         }
 271 }
 272
 273 static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
 274 {
 275         pud_t *pud = pud_offset(pgd, 0);
 276         unsigned long addr;
 277         unsigned i;
 278
 279         for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
 280                 addr = start + i * PUD_SIZE;
 281                 if (!pud_none(*pud)) {
 282                         walk_pmd(st, pud, addr);
 283                 } else {
 284                         note_page(st, addr, 2, pud_val(*pud));
 285                 }
 286         }
 287 }
 288
 289 static void walk_pgd(struct seq_file *m)
 290 {
 291         pgd_t *pgd = swapper_pg_dir;
 292         struct pg_state st;
 293         unsigned long addr;
 294         unsigned i, pgdoff = USER_PGTABLES_CEILING / PGDIR_SIZE;
 295
 296         memset(&st, 0, sizeof(st));
 297         st.seq = m;
 298         st.marker = address_markers;
 299
 300         pgd += pgdoff;
 301
 302         for (i = pgdoff; i < PTRS_PER_PGD; i++, pgd++) {
 303                 addr = i * PGDIR_SIZE;
 304                 if (!pgd_none(*pgd)) {
 305                         walk_pud(&st, pgd, addr);
 306                 } else {
 307                         note_page(&st, addr, 1, pgd_val(*pgd));
 308                 }
 309         }
 310
 311         note_page(&st, 0, 0, 0);
 312 }
 313
 314 static int ptdump_show(struct seq_file *m, void *v)
 315 {
 316         walk_pgd(m);
 317         return 0;
 318 }
 319
 320 static int ptdump_open(struct inode *inode, struct file *file)
 321 {
 322         return single_open(file, ptdump_show, NULL);
 323 }
 324
 325 static const struct file_operations ptdump_fops = {
 326         .open           = ptdump_open,
 327         .read           = seq_read,
 328         .llseek         = seq_lseek,
 329         .release        = single_release,
 330 };
 331
 332 static int ptdump_init(void)
 333 {
 334         struct dentry *pe;
 335         unsigned i, j;
 336
 337         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 338                 if (pg_level[i].bits)
 339                         for (j = 0; j < pg_level[i].num; j++)
 340                                 pg_level[i].mask |= pg_level[i].bits[j].mask;
 341
 342         address_markers[2].start_address = VMALLOC_START;
 343
 344         pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
 345                                  &ptdump_fops);
 346         return pe ? 0 : -ENOMEM;
 347 }
 348 __initcall(ptdump_init);