arch/riscv/mm/ptdump.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2019 SiFive
   4  */
   5
   6 #include <linux/efi.h>
   7 #include <linux/init.h>
   8 #include <linux/debugfs.h>
   9 #include <linux/seq_file.h>
  10 #include <linux/ptdump.h>
  11
  12 #include <asm/ptdump.h>
  13 #include <linux/pgtable.h>
  14 #include <asm/kasan.h>
  15
  16 #define pt_dump_seq_printf(m, fmt, args...)     \
  17 ({                                              \
  18         if (m)                                  \
  19                 seq_printf(m, fmt, ##args);     \
  20 })
  21
  22 #define pt_dump_seq_puts(m, fmt)        \
  23 ({                                      \
  24         if (m)                          \
  25                 seq_printf(m, fmt);     \
  26 })
  27
  28 /*
  29  * The page dumper groups page table entries of the same type into a single
  30  * description. It uses pg_state to track the range information while
  31  * iterating over the pte entries. When the continuity is broken it then
  32  * dumps out a description of the range.
  33  */
  34 struct pg_state {
  35         struct ptdump_state ptdump;
  36         struct seq_file *seq;
  37         const struct addr_marker *marker;
  38         unsigned long start_address;
  39         unsigned long start_pa;
  40         unsigned long last_pa;
  41         int level;
  42         u64 current_prot;
  43         bool check_wx;
  44         unsigned long wx_pages;
  45 };
  46
  47 /* Address marker */
  48 struct addr_marker {
  49         unsigned long start_address;
  50         const char *name;
  51 };
  52
  53 /* Private information for debugfs */
  54 struct ptd_mm_info {
  55         struct mm_struct                *mm;
  56         const struct addr_marker        *markers;
  57         unsigned long base_addr;
  58         unsigned long end;
  59 };
  60
  61 static struct addr_marker address_markers[] = {
  62 #ifdef CONFIG_KASAN
  63         {KASAN_SHADOW_START,    "Kasan shadow start"},
  64         {KASAN_SHADOW_END,      "Kasan shadow end"},
  65 #endif
  66         {FIXADDR_START,         "Fixmap start"},
  67         {FIXADDR_TOP,           "Fixmap end"},
  68         {PCI_IO_START,          "PCI I/O start"},
  69         {PCI_IO_END,            "PCI I/O end"},
  70 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  71         {VMEMMAP_START,         "vmemmap start"},
  72         {VMEMMAP_END,           "vmemmap end"},
  73 #endif
  74         {VMALLOC_START,         "vmalloc() area"},
  75         {VMALLOC_END,           "vmalloc() end"},
  76         {PAGE_OFFSET,           "Linear mapping"},
  77         {-1, NULL},
  78 };
  79
  80 static struct ptd_mm_info kernel_ptd_info = {
  81         .mm             = &init_mm,
  82         .markers        = address_markers,
  83         .base_addr      = KERN_VIRT_START,
  84         .end            = ULONG_MAX,
  85 };
  86
  87 #ifdef CONFIG_EFI
  88 static struct addr_marker efi_addr_markers[] = {
  89                 { 0,            "UEFI runtime start" },
  90                 { SZ_1G,        "UEFI runtime end" },
  91                 { -1,           NULL }
  92 };
  93
  94 static struct ptd_mm_info efi_ptd_info = {
  95         .mm             = &efi_mm,
  96         .markers        = efi_addr_markers,
  97         .base_addr      = 0,
  98         .end            = SZ_2G,
  99 };
 100 #endif
 101
 102 /* Page Table Entry */
 103 struct prot_bits {
 104         u64 mask;
 105         u64 val;
 106         const char *set;
 107         const char *clear;
 108 };
 109
 110 static const struct prot_bits pte_bits[] = {
 111         {
 112                 .mask = _PAGE_SOFT,
 113                 .val = _PAGE_SOFT,
 114                 .set = "RSW",
 115                 .clear = "   ",
 116         }, {
 117                 .mask = _PAGE_DIRTY,
 118                 .val = _PAGE_DIRTY,
 119                 .set = "D",
 120                 .clear = ".",
 121         }, {
 122                 .mask = _PAGE_ACCESSED,
 123                 .val = _PAGE_ACCESSED,
 124                 .set = "A",
 125                 .clear = ".",
 126         }, {
 127                 .mask = _PAGE_GLOBAL,
 128                 .val = _PAGE_GLOBAL,
 129                 .set = "G",
 130                 .clear = ".",
 131         }, {
 132                 .mask = _PAGE_USER,
 133                 .val = _PAGE_USER,
 134                 .set = "U",
 135                 .clear = ".",
 136         }, {
 137                 .mask = _PAGE_EXEC,
 138                 .val = _PAGE_EXEC,
 139                 .set = "X",
 140                 .clear = ".",
 141         }, {
 142                 .mask = _PAGE_WRITE,
 143                 .val = _PAGE_WRITE,
 144                 .set = "W",
 145                 .clear = ".",
 146         }, {
 147                 .mask = _PAGE_READ,
 148                 .val = _PAGE_READ,
 149                 .set = "R",
 150                 .clear = ".",
 151         }, {
 152                 .mask = _PAGE_PRESENT,
 153                 .val = _PAGE_PRESENT,
 154                 .set = "V",
 155                 .clear = ".",
 156         }
 157 };
 158
 159 /* Page Level */
 160 struct pg_level {
 161         const char *name;
 162         u64 mask;
 163 };
 164
 165 static struct pg_level pg_level[] = {
 166         { /* pgd */
 167                 .name = "PGD",
 168         }, { /* p4d */
 169                 .name = (CONFIG_PGTABLE_LEVELS > 4) ? "P4D" : "PGD",
 170         }, { /* pud */
 171                 .name = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
 172         }, { /* pmd */
 173                 .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD",
 174         }, { /* pte */
 175                 .name = "PTE",
 176         },
 177 };
 178
 179 static void dump_prot(struct pg_state *st)
 180 {
 181         unsigned int i;
 182
 183         for (i = 0; i < ARRAY_SIZE(pte_bits); i++) {
 184                 const char *s;
 185
 186                 if ((st->current_prot & pte_bits[i].mask) == pte_bits[i].val)
 187                         s = pte_bits[i].set;
 188                 else
 189                         s = pte_bits[i].clear;
 190
 191                 if (s)
 192                         pt_dump_seq_printf(st->seq, " %s", s);
 193         }
 194 }
 195
 196 #ifdef CONFIG_64BIT
 197 #define ADDR_FORMAT     "0x%016lx"
 198 #else
 199 #define ADDR_FORMAT     "0x%08lx"
 200 #endif
 201 static void dump_addr(struct pg_state *st, unsigned long addr)
 202 {
 203         static const char units[] = "KMGTPE";
 204         const char *unit = units;
 205         unsigned long delta;
 206
 207         pt_dump_seq_printf(st->seq, ADDR_FORMAT "-" ADDR_FORMAT "   ",
 208                            st->start_address, addr);
 209
 210         pt_dump_seq_printf(st->seq, " " ADDR_FORMAT " ", st->start_pa);
 211         delta = (addr - st->start_address) >> 10;
 212
 213         while (!(delta & 1023) && unit[1]) {
 214                 delta >>= 10;
 215                 unit++;
 216         }
 217
 218         pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
 219                            pg_level[st->level].name);
 220 }
 221
 222 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 223 {
 224         if (!st->check_wx)
 225                 return;
 226
 227         if ((st->current_prot & (_PAGE_WRITE | _PAGE_EXEC)) !=
 228             (_PAGE_WRITE | _PAGE_EXEC))
 229                 return;
 230
 231         WARN_ONCE(1, "riscv/mm: Found insecure W+X mapping at address %p/%pS\n",
 232                   (void *)st->start_address, (void *)st->start_address);
 233
 234         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 235 }
 236
 237 static void note_page(struct ptdump_state *pt_st, unsigned long addr,
 238                       int level, u64 val)
 239 {
 240         struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
 241         u64 pa = PFN_PHYS(pte_pfn(__pte(val)));
 242         u64 prot = 0;
 243
 244         if (level >= 0)
 245                 prot = val & pg_level[level].mask;
 246
 247         if (st->level == -1) {
 248                 st->level = level;
 249                 st->current_prot = prot;
 250                 st->start_address = addr;
 251                 st->start_pa = pa;
 252                 st->last_pa = pa;
 253                 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 254         } else if (prot != st->current_prot ||
 255                    level != st->level || addr >= st->marker[1].start_address) {
 256                 if (st->current_prot) {
 257                         note_prot_wx(st, addr);
 258                         dump_addr(st, addr);
 259                         dump_prot(st);
 260                         pt_dump_seq_puts(st->seq, "\n");
 261                 }
 262
 263                 while (addr >= st->marker[1].start_address) {
 264                         st->marker++;
 265                         pt_dump_seq_printf(st->seq, "---[ %s ]---\n",
 266                                            st->marker->name);
 267                 }
 268
 269                 st->start_address = addr;
 270                 st->start_pa = pa;
 271                 st->last_pa = pa;
 272                 st->current_prot = prot;
 273                 st->level = level;
 274         } else {
 275                 st->last_pa = pa;
 276         }
 277 }
 278
 279 static void ptdump_walk(struct seq_file *s, struct ptd_mm_info *pinfo)
 280 {
 281         struct pg_state st = {
 282                 .seq = s,
 283                 .marker = pinfo->markers,
 284                 .level = -1,
 285                 .ptdump = {
 286                         .note_page = note_page,
 287                         .range = (struct ptdump_range[]) {
 288                                 {pinfo->base_addr, pinfo->end},
 289                                 {0, 0}
 290                         }
 291                 }
 292         };
 293
 294         ptdump_walk_pgd(&st.ptdump, pinfo->mm, NULL);
 295 }
 296
 297 void ptdump_check_wx(void)
 298 {
 299         struct pg_state st = {
 300                 .seq = NULL,
 301                 .marker = (struct addr_marker[]) {
 302                         {0, NULL},
 303                         {-1, NULL},
 304                 },
 305                 .level = -1,
 306                 .check_wx = true,
 307                 .ptdump = {
 308                         .note_page = note_page,
 309                         .range = (struct ptdump_range[]) {
 310                                 {KERN_VIRT_START, ULONG_MAX},
 311                                 {0, 0}
 312                         }
 313                 }
 314         };
 315
 316         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 317
 318         if (st.wx_pages)
 319                 pr_warn("Checked W+X mappings: failed, %lu W+X pages found\n",
 320                         st.wx_pages);
 321         else
 322                 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
 323 }
 324
 325 static int ptdump_show(struct seq_file *m, void *v)
 326 {
 327         ptdump_walk(m, m->private);
 328
 329         return 0;
 330 }
 331
 332 DEFINE_SHOW_ATTRIBUTE(ptdump);
 333
 334 static int ptdump_init(void)
 335 {
 336         unsigned int i, j;
 337
 338         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 339                 for (j = 0; j < ARRAY_SIZE(pte_bits); j++)
 340                         pg_level[i].mask |= pte_bits[j].mask;
 341
 342         debugfs_create_file("kernel_page_tables", 0400, NULL, &kernel_ptd_info,
 343                             &ptdump_fops);
 344 #ifdef CONFIG_EFI
 345         if (efi_enabled(EFI_RUNTIME_SERVICES))
 346                 debugfs_create_file("efi_page_tables", 0400, NULL, &efi_ptd_info,
 347                                     &ptdump_fops);
 348 #endif
 349
 350         return 0;
 351 }
 352
 353 device_initcall(ptdump_init);