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