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 enum address_markers_idx {
  62 #ifdef CONFIG_KASAN
  63         KASAN_SHADOW_START_NR,
  64         KASAN_SHADOW_END_NR,
  65 #endif
  66         FIXMAP_START_NR,
  67         FIXMAP_END_NR,
  68         PCI_IO_START_NR,
  69         PCI_IO_END_NR,
  70 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  71         VMEMMAP_START_NR,
  72         VMEMMAP_END_NR,
  73 #endif
  74         VMALLOC_START_NR,
  75         VMALLOC_END_NR,
  76         PAGE_OFFSET_NR,
  77 #ifdef CONFIG_64BIT
  78         MODULES_MAPPING_NR,
  79         KERNEL_MAPPING_NR,
  80 #endif
  81         END_OF_SPACE_NR
  82 };
  83
  84 static struct addr_marker address_markers[] = {
  85 #ifdef CONFIG_KASAN
  86         {0, "Kasan shadow start"},
  87         {0, "Kasan shadow end"},
  88 #endif
  89         {0, "Fixmap start"},
  90         {0, "Fixmap end"},
  91         {0, "PCI I/O start"},
  92         {0, "PCI I/O end"},
  93 #ifdef CONFIG_SPARSEMEM_VMEMMAP
  94         {0, "vmemmap start"},
  95         {0, "vmemmap end"},
  96 #endif
  97         {0, "vmalloc() area"},
  98         {0, "vmalloc() end"},
  99         {0, "Linear mapping"},
 100 #ifdef CONFIG_64BIT
 101         {0, "Modules/BPF mapping"},
 102         {0, "Kernel mapping"},
 103 #endif
 104         {-1, NULL},
 105 };
 106
 107 static struct ptd_mm_info kernel_ptd_info = {
 108         .mm             = &init_mm,
 109         .markers        = address_markers,
 110         .base_addr      = 0,
 111         .end            = ULONG_MAX,
 112 };
 113
 114 #ifdef CONFIG_EFI
 115 static struct addr_marker efi_addr_markers[] = {
 116                 { 0,            "UEFI runtime start" },
 117                 { SZ_1G,        "UEFI runtime end" },
 118                 { -1,           NULL }
 119 };
 120
 121 static struct ptd_mm_info efi_ptd_info = {
 122         .mm             = &efi_mm,
 123         .markers        = efi_addr_markers,
 124         .base_addr      = 0,
 125         .end            = SZ_2G,
 126 };
 127 #endif
 128
 129 /* Page Table Entry */
 130 struct prot_bits {
 131         u64 mask;
 132         u64 val;
 133         const char *set;
 134         const char *clear;
 135 };
 136
 137 static const struct prot_bits pte_bits[] = {
 138         {
 139                 .mask = _PAGE_SOFT,
 140                 .val = _PAGE_SOFT,
 141                 .set = "RSW",
 142                 .clear = "   ",
 143         }, {
 144                 .mask = _PAGE_DIRTY,
 145                 .val = _PAGE_DIRTY,
 146                 .set = "D",
 147                 .clear = ".",
 148         }, {
 149                 .mask = _PAGE_ACCESSED,
 150                 .val = _PAGE_ACCESSED,
 151                 .set = "A",
 152                 .clear = ".",
 153         }, {
 154                 .mask = _PAGE_GLOBAL,
 155                 .val = _PAGE_GLOBAL,
 156                 .set = "G",
 157                 .clear = ".",
 158         }, {
 159                 .mask = _PAGE_USER,
 160                 .val = _PAGE_USER,
 161                 .set = "U",
 162                 .clear = ".",
 163         }, {
 164                 .mask = _PAGE_EXEC,
 165                 .val = _PAGE_EXEC,
 166                 .set = "X",
 167                 .clear = ".",
 168         }, {
 169                 .mask = _PAGE_WRITE,
 170                 .val = _PAGE_WRITE,
 171                 .set = "W",
 172                 .clear = ".",
 173         }, {
 174                 .mask = _PAGE_READ,
 175                 .val = _PAGE_READ,
 176                 .set = "R",
 177                 .clear = ".",
 178         }, {
 179                 .mask = _PAGE_PRESENT,
 180                 .val = _PAGE_PRESENT,
 181                 .set = "V",
 182                 .clear = ".",
 183         }
 184 };
 185
 186 /* Page Level */
 187 struct pg_level {
 188         const char *name;
 189         u64 mask;
 190 };
 191
 192 static struct pg_level pg_level[] = {
 193         { /* pgd */
 194                 .name = "PGD",
 195         }, { /* p4d */
 196                 .name = (CONFIG_PGTABLE_LEVELS > 4) ? "P4D" : "PGD",
 197         }, { /* pud */
 198                 .name = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
 199         }, { /* pmd */
 200                 .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD",
 201         }, { /* pte */
 202                 .name = "PTE",
 203         },
 204 };
 205
 206 static void dump_prot(struct pg_state *st)
 207 {
 208         unsigned int i;
 209
 210         for (i = 0; i < ARRAY_SIZE(pte_bits); i++) {
 211                 const char *s;
 212
 213                 if ((st->current_prot & pte_bits[i].mask) == pte_bits[i].val)
 214                         s = pte_bits[i].set;
 215                 else
 216                         s = pte_bits[i].clear;
 217
 218                 if (s)
 219                         pt_dump_seq_printf(st->seq, " %s", s);
 220         }
 221 }
 222
 223 #ifdef CONFIG_64BIT
 224 #define ADDR_FORMAT     "0x%016lx"
 225 #else
 226 #define ADDR_FORMAT     "0x%08lx"
 227 #endif
 228 static void dump_addr(struct pg_state *st, unsigned long addr)
 229 {
 230         static const char units[] = "KMGTPE";
 231         const char *unit = units;
 232         unsigned long delta;
 233
 234         pt_dump_seq_printf(st->seq, ADDR_FORMAT "-" ADDR_FORMAT "   ",
 235                            st->start_address, addr);
 236
 237         pt_dump_seq_printf(st->seq, " " ADDR_FORMAT " ", st->start_pa);
 238         delta = (addr - st->start_address) >> 10;
 239
 240         while (!(delta & 1023) && unit[1]) {
 241                 delta >>= 10;
 242                 unit++;
 243         }
 244
 245         pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
 246                            pg_level[st->level].name);
 247 }
 248
 249 static void note_prot_wx(struct pg_state *st, unsigned long addr)
 250 {
 251         if (!st->check_wx)
 252                 return;
 253
 254         if ((st->current_prot & (_PAGE_WRITE | _PAGE_EXEC)) !=
 255             (_PAGE_WRITE | _PAGE_EXEC))
 256                 return;
 257
 258         WARN_ONCE(1, "riscv/mm: Found insecure W+X mapping at address %p/%pS\n",
 259                   (void *)st->start_address, (void *)st->start_address);
 260
 261         st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
 262 }
 263
 264 static void note_page(struct ptdump_state *pt_st, unsigned long addr,
 265                       int level, u64 val)
 266 {
 267         struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
 268         u64 pa = PFN_PHYS(pte_pfn(__pte(val)));
 269         u64 prot = 0;
 270
 271         if (level >= 0)
 272                 prot = val & pg_level[level].mask;
 273
 274         if (st->level == -1) {
 275                 st->level = level;
 276                 st->current_prot = prot;
 277                 st->start_address = addr;
 278                 st->start_pa = pa;
 279                 st->last_pa = pa;
 280                 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
 281         } else if (prot != st->current_prot ||
 282                    level != st->level || addr >= st->marker[1].start_address) {
 283                 if (st->current_prot) {
 284                         note_prot_wx(st, addr);
 285                         dump_addr(st, addr);
 286                         dump_prot(st);
 287                         pt_dump_seq_puts(st->seq, "\n");
 288                 }
 289
 290                 while (addr >= st->marker[1].start_address) {
 291                         st->marker++;
 292                         pt_dump_seq_printf(st->seq, "---[ %s ]---\n",
 293                                            st->marker->name);
 294                 }
 295
 296                 st->start_address = addr;
 297                 st->start_pa = pa;
 298                 st->last_pa = pa;
 299                 st->current_prot = prot;
 300                 st->level = level;
 301         } else {
 302                 st->last_pa = pa;
 303         }
 304 }
 305
 306 static void ptdump_walk(struct seq_file *s, struct ptd_mm_info *pinfo)
 307 {
 308         struct pg_state st = {
 309                 .seq = s,
 310                 .marker = pinfo->markers,
 311                 .level = -1,
 312                 .ptdump = {
 313                         .note_page = note_page,
 314                         .range = (struct ptdump_range[]) {
 315                                 {pinfo->base_addr, pinfo->end},
 316                                 {0, 0}
 317                         }
 318                 }
 319         };
 320
 321         ptdump_walk_pgd(&st.ptdump, pinfo->mm, NULL);
 322 }
 323
 324 void ptdump_check_wx(void)
 325 {
 326         struct pg_state st = {
 327                 .seq = NULL,
 328                 .marker = (struct addr_marker[]) {
 329                         {0, NULL},
 330                         {-1, NULL},
 331                 },
 332                 .level = -1,
 333                 .check_wx = true,
 334                 .ptdump = {
 335                         .note_page = note_page,
 336                         .range = (struct ptdump_range[]) {
 337                                 {KERN_VIRT_START, ULONG_MAX},
 338                                 {0, 0}
 339                         }
 340                 }
 341         };
 342
 343         ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
 344
 345         if (st.wx_pages)
 346                 pr_warn("Checked W+X mappings: failed, %lu W+X pages found\n",
 347                         st.wx_pages);
 348         else
 349                 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
 350 }
 351
 352 static int ptdump_show(struct seq_file *m, void *v)
 353 {
 354         ptdump_walk(m, m->private);
 355
 356         return 0;
 357 }
 358
 359 DEFINE_SHOW_ATTRIBUTE(ptdump);
 360
 361 static int __init ptdump_init(void)
 362 {
 363         unsigned int i, j;
 364
 365 #ifdef CONFIG_KASAN
 366         address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
 367         address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
 368 #endif
 369         address_markers[FIXMAP_START_NR].start_address = FIXADDR_START;
 370         address_markers[FIXMAP_END_NR].start_address = FIXADDR_TOP;
 371         address_markers[PCI_IO_START_NR].start_address = PCI_IO_START;
 372         address_markers[PCI_IO_END_NR].start_address = PCI_IO_END;
 373 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 374         address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
 375         address_markers[VMEMMAP_END_NR].start_address = VMEMMAP_END;
 376 #endif
 377         address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
 378         address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
 379         address_markers[PAGE_OFFSET_NR].start_address = PAGE_OFFSET;
 380 #ifdef CONFIG_64BIT
 381         address_markers[MODULES_MAPPING_NR].start_address = MODULES_VADDR;
 382         address_markers[KERNEL_MAPPING_NR].start_address = kernel_map.virt_addr;
 383 #endif
 384
 385         kernel_ptd_info.base_addr = KERN_VIRT_START;
 386
 387         for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 388                 for (j = 0; j < ARRAY_SIZE(pte_bits); j++)
 389                         pg_level[i].mask |= pte_bits[j].mask;
 390
 391         debugfs_create_file("kernel_page_tables", 0400, NULL, &kernel_ptd_info,
 392                             &ptdump_fops);
 393 #ifdef CONFIG_EFI
 394         if (efi_enabled(EFI_RUNTIME_SERVICES))
 395                 debugfs_create_file("efi_page_tables", 0400, NULL, &efi_ptd_info,
 396                                     &ptdump_fops);
 397 #endif
 398
 399         return 0;
 400 }
 401
 402 device_initcall(ptdump_init);