arch/x86/mm/kasan_init_64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define DISABLE_BRANCH_PROFILING
   3 #define pr_fmt(fmt) "kasan: " fmt
   4
   5 /* cpu_feature_enabled() cannot be used this early */
   6 #define USE_EARLY_PGTABLE_L5
   7
   8 #include <linux/memblock.h>
   9 #include <linux/kasan.h>
  10 #include <linux/kdebug.h>
  11 #include <linux/mm.h>
  12 #include <linux/sched.h>
  13 #include <linux/sched/task.h>
  14 #include <linux/vmalloc.h>
  15
  16 #include <asm/e820/types.h>
  17 #include <asm/pgalloc.h>
  18 #include <asm/tlbflush.h>
  19 #include <asm/sections.h>
  20 #include <asm/cpu_entry_area.h>
  21
  22 extern struct range pfn_mapped[E820_MAX_ENTRIES];
  23
  24 static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
  25
  26 static __init void *early_alloc(size_t size, int nid, bool should_panic)
  27 {
  28         void *ptr = memblock_alloc_try_nid(size, size,
  29                         __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
  30
  31         if (!ptr && should_panic)
  32                 panic("%pS: Failed to allocate page, nid=%d from=%lx\n",
  33                       (void *)_RET_IP_, nid, __pa(MAX_DMA_ADDRESS));
  34
  35         return ptr;
  36 }
  37
  38 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
  39                                       unsigned long end, int nid)
  40 {
  41         pte_t *pte;
  42
  43         if (pmd_none(*pmd)) {
  44                 void *p;
  45
  46                 if (boot_cpu_has(X86_FEATURE_PSE) &&
  47                     ((end - addr) == PMD_SIZE) &&
  48                     IS_ALIGNED(addr, PMD_SIZE)) {
  49                         p = early_alloc(PMD_SIZE, nid, false);
  50                         if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
  51                                 return;
  52                         memblock_free(p, PMD_SIZE);
  53                 }
  54
  55                 p = early_alloc(PAGE_SIZE, nid, true);
  56                 pmd_populate_kernel(&init_mm, pmd, p);
  57         }
  58
  59         pte = pte_offset_kernel(pmd, addr);
  60         do {
  61                 pte_t entry;
  62                 void *p;
  63
  64                 if (!pte_none(*pte))
  65                         continue;
  66
  67                 p = early_alloc(PAGE_SIZE, nid, true);
  68                 entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
  69                 set_pte_at(&init_mm, addr, pte, entry);
  70         } while (pte++, addr += PAGE_SIZE, addr != end);
  71 }
  72
  73 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
  74                                       unsigned long end, int nid)
  75 {
  76         pmd_t *pmd;
  77         unsigned long next;
  78
  79         if (pud_none(*pud)) {
  80                 void *p;
  81
  82                 if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
  83                     ((end - addr) == PUD_SIZE) &&
  84                     IS_ALIGNED(addr, PUD_SIZE)) {
  85                         p = early_alloc(PUD_SIZE, nid, false);
  86                         if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
  87                                 return;
  88                         memblock_free(p, PUD_SIZE);
  89                 }
  90
  91                 p = early_alloc(PAGE_SIZE, nid, true);
  92                 pud_populate(&init_mm, pud, p);
  93         }
  94
  95         pmd = pmd_offset(pud, addr);
  96         do {
  97                 next = pmd_addr_end(addr, end);
  98                 if (!pmd_large(*pmd))
  99                         kasan_populate_pmd(pmd, addr, next, nid);
 100         } while (pmd++, addr = next, addr != end);
 101 }
 102
 103 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
 104                                       unsigned long end, int nid)
 105 {
 106         pud_t *pud;
 107         unsigned long next;
 108
 109         if (p4d_none(*p4d)) {
 110                 void *p = early_alloc(PAGE_SIZE, nid, true);
 111
 112                 p4d_populate(&init_mm, p4d, p);
 113         }
 114
 115         pud = pud_offset(p4d, addr);
 116         do {
 117                 next = pud_addr_end(addr, end);
 118                 if (!pud_large(*pud))
 119                         kasan_populate_pud(pud, addr, next, nid);
 120         } while (pud++, addr = next, addr != end);
 121 }
 122
 123 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 124                                       unsigned long end, int nid)
 125 {
 126         void *p;
 127         p4d_t *p4d;
 128         unsigned long next;
 129
 130         if (pgd_none(*pgd)) {
 131                 p = early_alloc(PAGE_SIZE, nid, true);
 132                 pgd_populate(&init_mm, pgd, p);
 133         }
 134
 135         p4d = p4d_offset(pgd, addr);
 136         do {
 137                 next = p4d_addr_end(addr, end);
 138                 kasan_populate_p4d(p4d, addr, next, nid);
 139         } while (p4d++, addr = next, addr != end);
 140 }
 141
 142 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
 143                                          int nid)
 144 {
 145         pgd_t *pgd;
 146         unsigned long next;
 147
 148         addr = addr & PAGE_MASK;
 149         end = round_up(end, PAGE_SIZE);
 150         pgd = pgd_offset_k(addr);
 151         do {
 152                 next = pgd_addr_end(addr, end);
 153                 kasan_populate_pgd(pgd, addr, next, nid);
 154         } while (pgd++, addr = next, addr != end);
 155 }
 156
 157 static void __init map_range(struct range *range)
 158 {
 159         unsigned long start;
 160         unsigned long end;
 161
 162         start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
 163         end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
 164
 165         kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
 166 }
 167
 168 static void __init clear_pgds(unsigned long start,
 169                         unsigned long end)
 170 {
 171         pgd_t *pgd;
 172         /* See comment in kasan_init() */
 173         unsigned long pgd_end = end & PGDIR_MASK;
 174
 175         for (; start < pgd_end; start += PGDIR_SIZE) {
 176                 pgd = pgd_offset_k(start);
 177                 /*
 178                  * With folded p4d, pgd_clear() is nop, use p4d_clear()
 179                  * instead.
 180                  */
 181                 if (pgtable_l5_enabled())
 182                         pgd_clear(pgd);
 183                 else
 184                         p4d_clear(p4d_offset(pgd, start));
 185         }
 186
 187         pgd = pgd_offset_k(start);
 188         for (; start < end; start += P4D_SIZE)
 189                 p4d_clear(p4d_offset(pgd, start));
 190 }
 191
 192 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 193 {
 194         unsigned long p4d;
 195
 196         if (!pgtable_l5_enabled())
 197                 return (p4d_t *)pgd;
 198
 199         p4d = pgd_val(*pgd) & PTE_PFN_MASK;
 200         p4d += __START_KERNEL_map - phys_base;
 201         return (p4d_t *)p4d + p4d_index(addr);
 202 }
 203
 204 static void __init kasan_early_p4d_populate(pgd_t *pgd,
 205                 unsigned long addr,
 206                 unsigned long end)
 207 {
 208         pgd_t pgd_entry;
 209         p4d_t *p4d, p4d_entry;
 210         unsigned long next;
 211
 212         if (pgd_none(*pgd)) {
 213                 pgd_entry = __pgd(_KERNPG_TABLE |
 214                                         __pa_nodebug(kasan_early_shadow_p4d));
 215                 set_pgd(pgd, pgd_entry);
 216         }
 217
 218         p4d = early_p4d_offset(pgd, addr);
 219         do {
 220                 next = p4d_addr_end(addr, end);
 221
 222                 if (!p4d_none(*p4d))
 223                         continue;
 224
 225                 p4d_entry = __p4d(_KERNPG_TABLE |
 226                                         __pa_nodebug(kasan_early_shadow_pud));
 227                 set_p4d(p4d, p4d_entry);
 228         } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 229 }
 230
 231 static void __init kasan_map_early_shadow(pgd_t *pgd)
 232 {
 233         /* See comment in kasan_init() */
 234         unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 235         unsigned long end = KASAN_SHADOW_END;
 236         unsigned long next;
 237
 238         pgd += pgd_index(addr);
 239         do {
 240                 next = pgd_addr_end(addr, end);
 241                 kasan_early_p4d_populate(pgd, addr, next);
 242         } while (pgd++, addr = next, addr != end);
 243 }
 244
 245 static void __init kasan_shallow_populate_p4ds(pgd_t *pgd,
 246                                                unsigned long addr,
 247                                                unsigned long end)
 248 {
 249         p4d_t *p4d;
 250         unsigned long next;
 251         void *p;
 252
 253         p4d = p4d_offset(pgd, addr);
 254         do {
 255                 next = p4d_addr_end(addr, end);
 256
 257                 if (p4d_none(*p4d)) {
 258                         p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true);
 259                         p4d_populate(&init_mm, p4d, p);
 260                 }
 261         } while (p4d++, addr = next, addr != end);
 262 }
 263
 264 static void __init kasan_shallow_populate_pgds(void *start, void *end)
 265 {
 266         unsigned long addr, next;
 267         pgd_t *pgd;
 268         void *p;
 269
 270         addr = (unsigned long)start;
 271         pgd = pgd_offset_k(addr);
 272         do {
 273                 next = pgd_addr_end(addr, (unsigned long)end);
 274
 275                 if (pgd_none(*pgd)) {
 276                         p = early_alloc(PAGE_SIZE, NUMA_NO_NODE, true);
 277                         pgd_populate(&init_mm, pgd, p);
 278                 }
 279
 280                 /*
 281                  * we need to populate p4ds to be synced when running in
 282                  * four level mode - see sync_global_pgds_l4()
 283                  */
 284                 kasan_shallow_populate_p4ds(pgd, addr, next);
 285         } while (pgd++, addr = next, addr != (unsigned long)end);
 286 }
 287
 288 void __init kasan_early_init(void)
 289 {
 290         int i;
 291         pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) |
 292                                 __PAGE_KERNEL | _PAGE_ENC;
 293         pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) | _KERNPG_TABLE;
 294         pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) | _KERNPG_TABLE;
 295         p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) | _KERNPG_TABLE;
 296
 297         /* Mask out unsupported __PAGE_KERNEL bits: */
 298         pte_val &= __default_kernel_pte_mask;
 299         pmd_val &= __default_kernel_pte_mask;
 300         pud_val &= __default_kernel_pte_mask;
 301         p4d_val &= __default_kernel_pte_mask;
 302
 303         for (i = 0; i < PTRS_PER_PTE; i++)
 304                 kasan_early_shadow_pte[i] = __pte(pte_val);
 305
 306         for (i = 0; i < PTRS_PER_PMD; i++)
 307                 kasan_early_shadow_pmd[i] = __pmd(pmd_val);
 308
 309         for (i = 0; i < PTRS_PER_PUD; i++)
 310                 kasan_early_shadow_pud[i] = __pud(pud_val);
 311
 312         for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
 313                 kasan_early_shadow_p4d[i] = __p4d(p4d_val);
 314
 315         kasan_map_early_shadow(early_top_pgt);
 316         kasan_map_early_shadow(init_top_pgt);
 317 }
 318
 319 static unsigned long kasan_mem_to_shadow_align_down(unsigned long va)
 320 {
 321         unsigned long shadow = (unsigned long)kasan_mem_to_shadow((void *)va);
 322
 323         return round_down(shadow, PAGE_SIZE);
 324 }
 325
 326 static unsigned long kasan_mem_to_shadow_align_up(unsigned long va)
 327 {
 328         unsigned long shadow = (unsigned long)kasan_mem_to_shadow((void *)va);
 329
 330         return round_up(shadow, PAGE_SIZE);
 331 }
 332
 333 void __init kasan_populate_shadow_for_vaddr(void *va, size_t size, int nid)
 334 {
 335         unsigned long shadow_start, shadow_end;
 336
 337         shadow_start = kasan_mem_to_shadow_align_down((unsigned long)va);
 338         shadow_end = kasan_mem_to_shadow_align_up((unsigned long)va + size);
 339         kasan_populate_shadow(shadow_start, shadow_end, nid);
 340 }
 341
 342 void __init kasan_init(void)
 343 {
 344         unsigned long shadow_cea_begin, shadow_cea_per_cpu_begin, shadow_cea_end;
 345         int i;
 346
 347         memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 348
 349         /*
 350          * We use the same shadow offset for 4- and 5-level paging to
 351          * facilitate boot-time switching between paging modes.
 352          * As result in 5-level paging mode KASAN_SHADOW_START and
 353          * KASAN_SHADOW_END are not aligned to PGD boundary.
 354          *
 355          * KASAN_SHADOW_START doesn't share PGD with anything else.
 356          * We claim whole PGD entry to make things easier.
 357          *
 358          * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 359          * bunch of things like kernel code, modules, EFI mapping, etc.
 360          * We need to take extra steps to not overwrite them.
 361          */
 362         if (pgtable_l5_enabled()) {
 363                 void *ptr;
 364
 365                 ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 366                 memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 367                 set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 368                                 __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 369         }
 370
 371         load_cr3(early_top_pgt);
 372         __flush_tlb_all();
 373
 374         clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
 375
 376         kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 377                         kasan_mem_to_shadow((void *)PAGE_OFFSET));
 378
 379         for (i = 0; i < E820_MAX_ENTRIES; i++) {
 380                 if (pfn_mapped[i].end == 0)
 381                         break;
 382
 383                 map_range(&pfn_mapped[i]);
 384         }
 385
 386         shadow_cea_begin = kasan_mem_to_shadow_align_down(CPU_ENTRY_AREA_BASE);
 387         shadow_cea_per_cpu_begin = kasan_mem_to_shadow_align_up(CPU_ENTRY_AREA_PER_CPU);
 388         shadow_cea_end = kasan_mem_to_shadow_align_up(CPU_ENTRY_AREA_BASE +
 389                                                       CPU_ENTRY_AREA_MAP_SIZE);
 390
 391         kasan_populate_early_shadow(
 392                 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 393                 kasan_mem_to_shadow((void *)VMALLOC_START));
 394
 395         /*
 396          * If we're in full vmalloc mode, don't back vmalloc space with early
 397          * shadow pages. Instead, prepopulate pgds/p4ds so they are synced to
 398          * the global table and we can populate the lower levels on demand.
 399          */
 400         if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
 401                 kasan_shallow_populate_pgds(
 402                         kasan_mem_to_shadow((void *)VMALLOC_START),
 403                         kasan_mem_to_shadow((void *)VMALLOC_END));
 404         else
 405                 kasan_populate_early_shadow(
 406                         kasan_mem_to_shadow((void *)VMALLOC_START),
 407                         kasan_mem_to_shadow((void *)VMALLOC_END));
 408
 409         kasan_populate_early_shadow(
 410                 kasan_mem_to_shadow((void *)VMALLOC_END + 1),
 411                 (void *)shadow_cea_begin);
 412
 413         /*
 414          * Populate the shadow for the shared portion of the CPU entry area.
 415          * Shadows for the per-CPU areas are mapped on-demand, as each CPU's
 416          * area is randomly placed somewhere in the 512GiB range and mapping
 417          * the entire 512GiB range is prohibitively expensive.
 418          */
 419         kasan_populate_shadow(shadow_cea_begin,
 420                               shadow_cea_per_cpu_begin, 0);
 421
 422         kasan_populate_early_shadow((void *)shadow_cea_end,
 423                         kasan_mem_to_shadow((void *)__START_KERNEL_map));
 424
 425         kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 426                               (unsigned long)kasan_mem_to_shadow(_end),
 427                               early_pfn_to_nid(__pa(_stext)));
 428
 429         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 430                                         (void *)KASAN_SHADOW_END);
 431
 432         load_cr3(init_top_pgt);
 433         __flush_tlb_all();
 434
 435         /*
 436          * kasan_early_shadow_page has been used as early shadow memory, thus
 437          * it may contain some garbage. Now we can clear and write protect it,
 438          * since after the TLB flush no one should write to it.
 439          */
 440         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 441         for (i = 0; i < PTRS_PER_PTE; i++) {
 442                 pte_t pte;
 443                 pgprot_t prot;
 444
 445                 prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
 446                 pgprot_val(prot) &= __default_kernel_pte_mask;
 447
 448                 pte = __pte(__pa(kasan_early_shadow_page) | pgprot_val(prot));
 449                 set_pte(&kasan_early_shadow_pte[i], pte);
 450         }
 451         /* Flush TLBs again to be sure that write protection applied. */
 452         __flush_tlb_all();
 453
 454         init_task.kasan_depth = 0;
 455         pr_info("KernelAddressSanitizer initialized\n");
 456 }