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_leaf(*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_leaf(*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 } 457