arch/arm64/mm/ptdump.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2014, The Linux Foundation. All rights reserved.
   4  * Debug helper to dump the current kernel pagetables of the system
   5  * so that we can see what the various memory ranges are set to.
   6  *
   7  * Derived from x86 and arm implementation:
   8  * (C) Copyright 2008 Intel Corporation
   9  *
  10  * Author: Arjan van de Ven <arjan@linux.intel.com>
  11  */
  12 #include <linux/debugfs.h>
  13 #include <linux/errno.h>
  14 #include <linux/fs.h>
  15 #include <linux/io.h>
  16 #include <linux/init.h>
  17 #include <linux/mm.h>
  18 #include <linux/ptdump.h>
  19 #include <linux/sched.h>
  20 #include <linux/seq_file.h>
  21
  22 #include <asm/fixmap.h>
  23 #include <asm/kasan.h>
  24 #include <asm/memory.h>
  25 #include <asm/pgtable-hwdef.h>
  26 #include <asm/ptdump.h>
  27
  28
  29 enum address_markers_idx {
  30         PAGE_OFFSET_NR = 0,
  31         PAGE_END_NR,
  32 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
  33         KASAN_START_NR,
  34 #endif
  35 };
  36
  37 static struct addr_marker address_markers[] = {
  38         { PAGE_OFFSET,                  "Linear Mapping start" },
  39         { 0 /* PAGE_END */,             "Linear Mapping end" },
  40 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
  41         { 0 /* KASAN_SHADOW_START */,   "Kasan shadow start" },
  42         { KASAN_SHADOW_END,             "Kasan shadow end" },
  43 #endif
  44         { BPF_JIT_REGION_START,         "BPF start" },
  45         { BPF_JIT_REGION_END,           "BPF end" },
  46         { MODULES_VADDR,                "Modules start" },
  47         { MODULES_END,                  "Modules end" },
  48         { VMALLOC_START,                "vmalloc() area" },
  49         { VMALLOC_END,                  "vmalloc() end" },
  50         { FIXADDR_START,                "Fixmap start" },
  51         { FIXADDR_TOP,                  "Fixmap end" },
  52         { PCI_IO_START,                 "PCI I/O start" },
  53         { PCI_IO_END,                   "PCI I/O end" },
  54 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  55         { VMEMMAP_START,                "vmemmap start" },
  56         { VMEMMAP_START + VMEMMAP_SIZE, "vmemmap end" },
  57 #endif
  58         { -1,                           NULL },
  59 };
  60
  61 #define pt_dump_seq_printf(m, fmt, args...)     \
  62 ({                                              \
  63         if (m)                                  \
  64                 seq_printf(m, fmt, ##args);     \
  65 })
  66
  67 #define pt_dump_seq_puts(m, fmt)        \
  68 ({                                      \
  69         if (m)                          \
  70                 seq_printf(m, fmt);     \
  71 })
  72
  73 /*
  74  * The page dumper groups page table entries of the same type into a single
  75  * description. It uses pg_state to track the range information while
  76  * iterating over the pte entries. When the continuity is broken it then
  77  * dumps out a description of the range.
  78  */
  79 struct pg_state {
  80         struct ptdump_state ptdump;
  81         struct seq_file *seq;
  82         const struct addr_marker *marker;
  83         unsigned long start_address;
  84         int level;
  85         u64 current_prot;
  86         bool check_wx;
  87         unsigned long wx_pages;
  88         unsigned long uxn_pages;
  89 };
  90
  91 struct prot_bits {
  92         u64             mask;
  93         u64             val;
  94         const char      *set;
  95         const char      *clear;
  96 };
  97
  98 static const struct prot_bits pte_bits[] = {
  99         {
 100                 .mask   = PTE_VALID,
 101                 .val    = PTE_VALID,
 102                 .set    = " ",
 103                 .clear  = "F",
 104         }, {
 105                 .mask   = PTE_USER,
 106                 .val    = PTE_USER,
 107                 .set    = "USR",
 108                 .clear  = "   ",
 109         }, {
 110                 .mask   = PTE_RDONLY,
 111                 .val    = PTE_RDONLY,
 112                 .set    = "ro",
 113                 .clear  = "RW",
 114         }, {
 115                 .mask   = PTE_PXN,
 116                 .val    = PTE_PXN,
 117                 .set    = "NX",
 118                 .clear  = "x ",
 119         }, {
 120                 .mask   = PTE_SHARED,
 121                 .val    = PTE_SHARED,
 122                 .set    = "SHD",
 123                 .clear  = "   ",
 124         }, {
 125                 .mask   = PTE_AF,
 126                 .val    = PTE_AF,
 127                 .set    = "AF",
 128                 .clear  = "  ",
 129         }, {
 130                 .mask   = PTE_NG,
 131                 .val    = PTE_NG,
 132                 .set    = "NG",
 133                 .clear  = "  ",
 134         }, {
 135                 .mask   = PTE_CONT,
 136                 .val    = PTE_CONT,
 137                 .set    = "CON",
 138                 .clear  = "   ",
 139         }, {
 140                 .mask   = PTE_TABLE_BIT,
 141                 .val    = PTE_TABLE_BIT,
 142                 .set    = "   ",
 143                 .clear  = "BLK",
 144         }, {
 145                 .mask   = PTE_UXN,
 146                 .val    = PTE_UXN,
 147                 .set    = "UXN",
 148                 .clear  = "   ",
 149         }, {
 150                 .mask   = PTE_GP,
 151                 .val    = PTE_GP,
 152                 .set    = "GP",
 153                 .clear  = "  ",
 154         }, {
 155                 .mask   = PTE_ATTRINDX_MASK,
 156                 .val    = PTE_ATTRINDX(MT_DEVICE_nGnRnE),
 157                 .set    = "DEVICE/nGnRnE",
 158         }, {
 159                 .mask   = PTE_ATTRINDX_MASK,
 160                 .val    = PTE_ATTRINDX(MT_DEVICE_nGnRE),
 161                 .set    = "DEVICE/nGnRE",
 162         }, {
 163                 .mask   = PTE_ATTRINDX_MASK,
 164                 .val    = PTE_ATTRINDX(MT_DEVICE_GRE),
 165                 .set    = "DEVICE/GRE",
 166         }, {
 167                 .mask   = PTE_ATTRINDX_MASK,
 168                 .val    = PTE_ATTRINDX(MT_NORMAL_NC),
 169                 .set    = "MEM/NORMAL-NC",
 170         }, {
 171                 .mask   = PTE_ATTRINDX_MASK,
 172                 .val    = PTE_ATTRINDX(MT_NORMAL),
 173                 .set    = "MEM/NORMAL",
 174         }, {
 175                 .mask   = PTE_ATTRINDX_MASK,
 176                 .val    = PTE_ATTRINDX(MT_NORMAL_TAGGED),
 177                 .set    = "MEM/NORMAL-TAGGED",
 178         }
 179 };
 180
 181 struct pg_level {
 182         const struct prot_bits *bits;
 183         const char *name;
 184         size_t num;
 185         u64 mask;
 186 };
 187
 188 static struct pg_level pg_level[] = {
 189         { /* pgd */
 190                 .name   = "PGD",
 191                 .bits   = pte_bits,
 192                 .num    = ARRAY_SIZE(pte_bits),
 193         }, { /* p4d */
 194                 .name   = "P4D",
 195                 .bits   = pte_bits,
 196                 .num    = ARRAY_SIZE(pte_bits),
 197         }, { /* pud */
 198                 .name   = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
 199                 .bits   = pte_bits,
 200                 .num    = ARRAY_SIZE(pte_bits),
 201         }, { /* pmd */
 202                 .name   = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD",
 203                 .bits   = pte_bits,
 204                 .num    = ARRAY_SIZE(pte_bits),
 205         }, { /* pte */
 206                 .name   = "PTE",
 207                 .bits   = pte_bits,
 208                 .num    = ARRAY_SIZE(pte_bits),
 209         },
 210 };
 211
 212 static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
 213                         size_t num)
 214 {
 215         unsigned i;
 216
 217         for (i = 0; i < num; i++, bits++) {
 218                 const char *s;
 219
 220                 if ((st->current_prot & bits->mask) == bits->val)
 221                         s = bits->set;
 222                 else
 223                         s = bits->clear;
 224
 225                 if (s)
 226                         pt_dump_seq_printf(st->seq, " %s", s);
 227         }
 228 }
 229
 230 static void note_prot_uxn(struct pg_state *st, unsigned long addr)
 231 {
 232         if (!st->check_wx)
 233                 return;
 234
 235         if ((st->current_prot & PTE_UXN) == PTE_UXN)
 236                 return;
 237
 238         WARN_ONCE(1, "arm64/mm: Found non-UXN mapping at address %p/%pS\n",
 239                   (void *)st->start_address, (void *)st->start_address);
 240
 241         st->uxn_pages += (addr - st->start_address) / PAGE_SIZE;
 242 }
 243
 244 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 245 {
 246         if (!st->check_wx)
 247                 return;
 248         if ((st->current_prot & PTE_RDONLY) == PTE_RDONLY)
 249                 return;
 250         if ((st->current_prot & PTE_PXN) == PTE_PXN)
 251                 return;
 252
 253         WARN_ONCE(1, "arm64/mm: Found insecure W+X mapping at address %p/%pS\n",
 254                   (void *)st->start_address, (void *)st->start_address);
 255
 256         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 257 }
 258
 259 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 260                       u64 val)
 261 {
 262         struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
 263         static const char units[] = "KMGTPE";
 264         u64 prot = 0;
 265
 266         if (level >= 0)
 267                 prot = val & pg_level[level].mask;
 268
 269         if (st->level == -1) {
 270                 st->level = level;
 271                 st->current_prot = prot;
 272                 st->start_address = addr;
 273                 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 274         } else if (prot != st->current_prot || level != st->level ||
 275                    addr >= st->marker[1].start_address) {
 276                 const char *unit = units;
 277                 unsigned long delta;
 278
 279                 if (st->current_prot) {
 280                         note_prot_uxn(st, addr);
 281                         note_prot_wx(st, addr);
 282                 }
 283
 284                 pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx   ",
 285                                    st->start_address, addr);
 286
 287                 delta = (addr - st->start_address) >> 10;
 288                 while (!(delta & 1023) && unit[1]) {
 289                         delta >>= 10;
 290                         unit++;
 291                 }
 292                 pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
 293                                    pg_level[st->level].name);
 294                 if (st->current_prot && pg_level[st->level].bits)
 295                         dump_prot(st, pg_level[st->level].bits,
 296                                   pg_level[st->level].num);
 297                 pt_dump_seq_puts(st->seq, "\n");
 298
 299                 if (addr >= st->marker[1].start_address) {
 300                         st->marker++;
 301                         pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 302                 }
 303
 304                 st->start_address = addr;
 305                 st->current_prot = prot;
 306                 st->level = level;
 307         }
 308
 309         if (addr >= st->marker[1].start_address) {
 310                 st->marker++;
 311                 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 312         }
 313
 314 }
 315
 316 void ptdump_walk(struct seq_file *s, struct ptdump_info *info)
 317 {
 318         unsigned long end = ~0UL;
 319         struct pg_state st;
 320
 321         if (info->base_addr < TASK_SIZE_64)
 322                 end = TASK_SIZE_64;
 323
 324         st = (struct pg_state){
 325                 .seq = s,
 326                 .marker = info->markers,
 327                 .ptdump = {
 328                         .note_page = note_page,
 329                         .range = (struct ptdump_range[]){
 330                                 {info->base_addr, end},
 331                                 {0, 0}
 332                         }
 333                 }
 334         };
 335
 336         ptdump_walk_pgd(&st.ptdump, info->mm, NULL);
 337 }
 338
 339 static void ptdump_initialize(void)
 340 {
 341         unsigned i, j;
 342
 343         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 344                 if (pg_level[i].bits)
 345                         for (j = 0; j < pg_level[i].num; j++)
 346                                 pg_level[i].mask |= pg_level[i].bits[j].mask;
 347 }
 348
 349 static struct ptdump_info kernel_ptdump_info = {
 350         .mm             = &init_mm,
 351         .markers        = address_markers,
 352         .base_addr      = PAGE_OFFSET,
 353 };
 354
 355 void ptdump_check_wx(void)
 356 {
 357         struct pg_state st = {
 358                 .seq = NULL,
 359                 .marker = (struct addr_marker[]) {
 360                         { 0, NULL},
 361                         { -1, NULL},
 362                 },
 363                 .level = -1,
 364                 .check_wx = true,
 365                 .ptdump = {
 366                         .note_page = note_page,
 367                         .range = (struct ptdump_range[]) {
 368                                 {PAGE_OFFSET, ~0UL},
 369                                 {0, 0}
 370                         }
 371                 }
 372         };
 373
 374         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 375
 376         if (st.wx_pages || st.uxn_pages)
 377                 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\n",
 378                         st.wx_pages, st.uxn_pages);
 379         else
 380                 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
 381 }
 382
 383 static int ptdump_init(void)
 384 {
 385         address_markers[PAGE_END_NR].start_address = PAGE_END;
 386 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 387         address_markers[KASAN_START_NR].start_address = KASAN_SHADOW_START;
 388 #endif
 389         ptdump_initialize();
 390         ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
 391         return 0;
 392 }
 393 device_initcall(ptdump_init);