1 /* 2 * Based on arch/arm/mm/mmu.c 3 * 4 * Copyright (C) 1995-2005 Russell King 5 * Copyright (C) 2012 ARM Ltd. 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program. If not, see <http://www.gnu.org/licenses/>. 18 */ 19 20 #include <linux/export.h> 21 #include <linux/kernel.h> 22 #include <linux/errno.h> 23 #include <linux/init.h> 24 #include <linux/libfdt.h> 25 #include <linux/mman.h> 26 #include <linux/nodemask.h> 27 #include <linux/memblock.h> 28 #include <linux/fs.h> 29 #include <linux/io.h> 30 #include <linux/slab.h> 31 #include <linux/stop_machine.h> 32 33 #include <asm/barrier.h> 34 #include <asm/cputype.h> 35 #include <asm/fixmap.h> 36 #include <asm/kasan.h> 37 #include <asm/kernel-pgtable.h> 38 #include <asm/sections.h> 39 #include <asm/setup.h> 40 #include <asm/sizes.h> 41 #include <asm/tlb.h> 42 #include <asm/memblock.h> 43 #include <asm/mmu_context.h> 44 45 #include "mm.h" 46 47 u64 idmap_t0sz = TCR_T0SZ(VA_BITS); 48 49 /* 50 * Empty_zero_page is a special page that is used for zero-initialized data 51 * and COW. 52 */ 53 unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss; 54 EXPORT_SYMBOL(empty_zero_page); 55 56 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 57 unsigned long size, pgprot_t vma_prot) 58 { 59 if (!pfn_valid(pfn)) 60 return pgprot_noncached(vma_prot); 61 else if (file->f_flags & O_SYNC) 62 return pgprot_writecombine(vma_prot); 63 return vma_prot; 64 } 65 EXPORT_SYMBOL(phys_mem_access_prot); 66 67 static phys_addr_t __init early_pgtable_alloc(void) 68 { 69 phys_addr_t phys; 70 void *ptr; 71 72 phys = memblock_alloc(PAGE_SIZE, PAGE_SIZE); 73 BUG_ON(!phys); 74 75 /* 76 * The FIX_{PGD,PUD,PMD} slots may be in active use, but the FIX_PTE 77 * slot will be free, so we can (ab)use the FIX_PTE slot to initialise 78 * any level of table. 79 */ 80 ptr = pte_set_fixmap(phys); 81 82 memset(ptr, 0, PAGE_SIZE); 83 84 /* 85 * Implicit barriers also ensure the zeroed page is visible to the page 86 * table walker 87 */ 88 pte_clear_fixmap(); 89 90 return phys; 91 } 92 93 /* 94 * remap a PMD into pages 95 */ 96 static void split_pmd(pmd_t *pmd, pte_t *pte) 97 { 98 unsigned long pfn = pmd_pfn(*pmd); 99 int i = 0; 100 101 do { 102 /* 103 * Need to have the least restrictive permissions available 104 * permissions will be fixed up later 105 */ 106 set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC)); 107 pfn++; 108 } while (pte++, i++, i < PTRS_PER_PTE); 109 } 110 111 static void alloc_init_pte(pmd_t *pmd, unsigned long addr, 112 unsigned long end, unsigned long pfn, 113 pgprot_t prot, 114 phys_addr_t (*pgtable_alloc)(void)) 115 { 116 pte_t *pte; 117 118 if (pmd_none(*pmd) || pmd_sect(*pmd)) { 119 phys_addr_t pte_phys; 120 BUG_ON(!pgtable_alloc); 121 pte_phys = pgtable_alloc(); 122 pte = pte_set_fixmap(pte_phys); 123 if (pmd_sect(*pmd)) 124 split_pmd(pmd, pte); 125 __pmd_populate(pmd, pte_phys, PMD_TYPE_TABLE); 126 flush_tlb_all(); 127 pte_clear_fixmap(); 128 } 129 BUG_ON(pmd_bad(*pmd)); 130 131 pte = pte_set_fixmap_offset(pmd, addr); 132 do { 133 set_pte(pte, pfn_pte(pfn, prot)); 134 pfn++; 135 } while (pte++, addr += PAGE_SIZE, addr != end); 136 137 pte_clear_fixmap(); 138 } 139 140 static void split_pud(pud_t *old_pud, pmd_t *pmd) 141 { 142 unsigned long addr = pud_pfn(*old_pud) << PAGE_SHIFT; 143 pgprot_t prot = __pgprot(pud_val(*old_pud) ^ addr); 144 int i = 0; 145 146 do { 147 set_pmd(pmd, __pmd(addr | pgprot_val(prot))); 148 addr += PMD_SIZE; 149 } while (pmd++, i++, i < PTRS_PER_PMD); 150 } 151 152 static void alloc_init_pmd(pud_t *pud, unsigned long addr, unsigned long end, 153 phys_addr_t phys, pgprot_t prot, 154 phys_addr_t (*pgtable_alloc)(void)) 155 { 156 pmd_t *pmd; 157 unsigned long next; 158 159 /* 160 * Check for initial section mappings in the pgd/pud and remove them. 161 */ 162 if (pud_none(*pud) || pud_sect(*pud)) { 163 phys_addr_t pmd_phys; 164 BUG_ON(!pgtable_alloc); 165 pmd_phys = pgtable_alloc(); 166 pmd = pmd_set_fixmap(pmd_phys); 167 if (pud_sect(*pud)) { 168 /* 169 * need to have the 1G of mappings continue to be 170 * present 171 */ 172 split_pud(pud, pmd); 173 } 174 __pud_populate(pud, pmd_phys, PUD_TYPE_TABLE); 175 flush_tlb_all(); 176 pmd_clear_fixmap(); 177 } 178 BUG_ON(pud_bad(*pud)); 179 180 pmd = pmd_set_fixmap_offset(pud, addr); 181 do { 182 next = pmd_addr_end(addr, end); 183 /* try section mapping first */ 184 if (((addr | next | phys) & ~SECTION_MASK) == 0) { 185 pmd_t old_pmd =*pmd; 186 set_pmd(pmd, __pmd(phys | 187 pgprot_val(mk_sect_prot(prot)))); 188 /* 189 * Check for previous table entries created during 190 * boot (__create_page_tables) and flush them. 191 */ 192 if (!pmd_none(old_pmd)) { 193 flush_tlb_all(); 194 if (pmd_table(old_pmd)) { 195 phys_addr_t table = pmd_page_paddr(old_pmd); 196 if (!WARN_ON_ONCE(slab_is_available())) 197 memblock_free(table, PAGE_SIZE); 198 } 199 } 200 } else { 201 alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys), 202 prot, pgtable_alloc); 203 } 204 phys += next - addr; 205 } while (pmd++, addr = next, addr != end); 206 207 pmd_clear_fixmap(); 208 } 209 210 static inline bool use_1G_block(unsigned long addr, unsigned long next, 211 unsigned long phys) 212 { 213 if (PAGE_SHIFT != 12) 214 return false; 215 216 if (((addr | next | phys) & ~PUD_MASK) != 0) 217 return false; 218 219 return true; 220 } 221 222 static void alloc_init_pud(pgd_t *pgd, unsigned long addr, unsigned long end, 223 phys_addr_t phys, pgprot_t prot, 224 phys_addr_t (*pgtable_alloc)(void)) 225 { 226 pud_t *pud; 227 unsigned long next; 228 229 if (pgd_none(*pgd)) { 230 phys_addr_t pud_phys; 231 BUG_ON(!pgtable_alloc); 232 pud_phys = pgtable_alloc(); 233 __pgd_populate(pgd, pud_phys, PUD_TYPE_TABLE); 234 } 235 BUG_ON(pgd_bad(*pgd)); 236 237 pud = pud_set_fixmap_offset(pgd, addr); 238 do { 239 next = pud_addr_end(addr, end); 240 241 /* 242 * For 4K granule only, attempt to put down a 1GB block 243 */ 244 if (use_1G_block(addr, next, phys)) { 245 pud_t old_pud = *pud; 246 set_pud(pud, __pud(phys | 247 pgprot_val(mk_sect_prot(prot)))); 248 249 /* 250 * If we have an old value for a pud, it will 251 * be pointing to a pmd table that we no longer 252 * need (from swapper_pg_dir). 253 * 254 * Look up the old pmd table and free it. 255 */ 256 if (!pud_none(old_pud)) { 257 flush_tlb_all(); 258 if (pud_table(old_pud)) { 259 phys_addr_t table = pud_page_paddr(old_pud); 260 if (!WARN_ON_ONCE(slab_is_available())) 261 memblock_free(table, PAGE_SIZE); 262 } 263 } 264 } else { 265 alloc_init_pmd(pud, addr, next, phys, prot, 266 pgtable_alloc); 267 } 268 phys += next - addr; 269 } while (pud++, addr = next, addr != end); 270 271 pud_clear_fixmap(); 272 } 273 274 /* 275 * Create the page directory entries and any necessary page tables for the 276 * mapping specified by 'md'. 277 */ 278 static void init_pgd(pgd_t *pgd, phys_addr_t phys, unsigned long virt, 279 phys_addr_t size, pgprot_t prot, 280 phys_addr_t (*pgtable_alloc)(void)) 281 { 282 unsigned long addr, length, end, next; 283 284 /* 285 * If the virtual and physical address don't have the same offset 286 * within a page, we cannot map the region as the caller expects. 287 */ 288 if (WARN_ON((phys ^ virt) & ~PAGE_MASK)) 289 return; 290 291 phys &= PAGE_MASK; 292 addr = virt & PAGE_MASK; 293 length = PAGE_ALIGN(size + (virt & ~PAGE_MASK)); 294 295 end = addr + length; 296 do { 297 next = pgd_addr_end(addr, end); 298 alloc_init_pud(pgd, addr, next, phys, prot, pgtable_alloc); 299 phys += next - addr; 300 } while (pgd++, addr = next, addr != end); 301 } 302 303 static phys_addr_t late_pgtable_alloc(void) 304 { 305 void *ptr = (void *)__get_free_page(PGALLOC_GFP); 306 BUG_ON(!ptr); 307 308 /* Ensure the zeroed page is visible to the page table walker */ 309 dsb(ishst); 310 return __pa(ptr); 311 } 312 313 static void __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys, 314 unsigned long virt, phys_addr_t size, 315 pgprot_t prot, 316 phys_addr_t (*alloc)(void)) 317 { 318 init_pgd(pgd_offset_raw(pgdir, virt), phys, virt, size, prot, alloc); 319 } 320 321 /* 322 * This function can only be used to modify existing table entries, 323 * without allocating new levels of table. Note that this permits the 324 * creation of new section or page entries. 325 */ 326 static void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt, 327 phys_addr_t size, pgprot_t prot) 328 { 329 if (virt < VMALLOC_START) { 330 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", 331 &phys, virt); 332 return; 333 } 334 __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, 335 NULL); 336 } 337 338 void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, 339 unsigned long virt, phys_addr_t size, 340 pgprot_t prot) 341 { 342 __create_pgd_mapping(mm->pgd, phys, virt, size, prot, 343 late_pgtable_alloc); 344 } 345 346 static void create_mapping_late(phys_addr_t phys, unsigned long virt, 347 phys_addr_t size, pgprot_t prot) 348 { 349 if (virt < VMALLOC_START) { 350 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", 351 &phys, virt); 352 return; 353 } 354 355 __create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, 356 late_pgtable_alloc); 357 } 358 359 static void __init __map_memblock(pgd_t *pgd, phys_addr_t start, phys_addr_t end) 360 { 361 362 unsigned long kernel_start = __pa(_stext); 363 unsigned long kernel_end = __pa(_end); 364 365 /* 366 * The kernel itself is mapped at page granularity. Map all other 367 * memory, making sure we don't overwrite the existing kernel mappings. 368 */ 369 370 /* No overlap with the kernel. */ 371 if (end < kernel_start || start >= kernel_end) { 372 __create_pgd_mapping(pgd, start, __phys_to_virt(start), 373 end - start, PAGE_KERNEL, 374 early_pgtable_alloc); 375 return; 376 } 377 378 /* 379 * This block overlaps the kernel mapping. Map the portion(s) which 380 * don't overlap. 381 */ 382 if (start < kernel_start) 383 __create_pgd_mapping(pgd, start, 384 __phys_to_virt(start), 385 kernel_start - start, PAGE_KERNEL, 386 early_pgtable_alloc); 387 if (kernel_end < end) 388 __create_pgd_mapping(pgd, kernel_end, 389 __phys_to_virt(kernel_end), 390 end - kernel_end, PAGE_KERNEL, 391 early_pgtable_alloc); 392 } 393 394 static void __init map_mem(pgd_t *pgd) 395 { 396 struct memblock_region *reg; 397 398 /* map all the memory banks */ 399 for_each_memblock(memory, reg) { 400 phys_addr_t start = reg->base; 401 phys_addr_t end = start + reg->size; 402 403 if (start >= end) 404 break; 405 if (memblock_is_nomap(reg)) 406 continue; 407 408 __map_memblock(pgd, start, end); 409 } 410 } 411 412 #ifdef CONFIG_DEBUG_RODATA 413 void mark_rodata_ro(void) 414 { 415 create_mapping_late(__pa(_stext), (unsigned long)_stext, 416 (unsigned long)_etext - (unsigned long)_stext, 417 PAGE_KERNEL_ROX); 418 419 } 420 #endif 421 422 void fixup_init(void) 423 { 424 create_mapping_late(__pa(__init_begin), (unsigned long)__init_begin, 425 (unsigned long)__init_end - (unsigned long)__init_begin, 426 PAGE_KERNEL); 427 } 428 429 static void __init map_kernel_chunk(pgd_t *pgd, void *va_start, void *va_end, 430 pgprot_t prot) 431 { 432 phys_addr_t pa_start = __pa(va_start); 433 unsigned long size = va_end - va_start; 434 435 BUG_ON(!PAGE_ALIGNED(pa_start)); 436 BUG_ON(!PAGE_ALIGNED(size)); 437 438 __create_pgd_mapping(pgd, pa_start, (unsigned long)va_start, size, prot, 439 early_pgtable_alloc); 440 } 441 442 /* 443 * Create fine-grained mappings for the kernel. 444 */ 445 static void __init map_kernel(pgd_t *pgd) 446 { 447 448 map_kernel_chunk(pgd, _stext, _etext, PAGE_KERNEL_EXEC); 449 map_kernel_chunk(pgd, __init_begin, __init_end, PAGE_KERNEL_EXEC); 450 map_kernel_chunk(pgd, _data, _end, PAGE_KERNEL); 451 452 /* 453 * The fixmap falls in a separate pgd to the kernel, and doesn't live 454 * in the carveout for the swapper_pg_dir. We can simply re-use the 455 * existing dir for the fixmap. 456 */ 457 set_pgd(pgd_offset_raw(pgd, FIXADDR_START), *pgd_offset_k(FIXADDR_START)); 458 459 kasan_copy_shadow(pgd); 460 } 461 462 /* 463 * paging_init() sets up the page tables, initialises the zone memory 464 * maps and sets up the zero page. 465 */ 466 void __init paging_init(void) 467 { 468 phys_addr_t pgd_phys = early_pgtable_alloc(); 469 pgd_t *pgd = pgd_set_fixmap(pgd_phys); 470 471 map_kernel(pgd); 472 map_mem(pgd); 473 474 /* 475 * We want to reuse the original swapper_pg_dir so we don't have to 476 * communicate the new address to non-coherent secondaries in 477 * secondary_entry, and so cpu_switch_mm can generate the address with 478 * adrp+add rather than a load from some global variable. 479 * 480 * To do this we need to go via a temporary pgd. 481 */ 482 cpu_replace_ttbr1(__va(pgd_phys)); 483 memcpy(swapper_pg_dir, pgd, PAGE_SIZE); 484 cpu_replace_ttbr1(swapper_pg_dir); 485 486 pgd_clear_fixmap(); 487 memblock_free(pgd_phys, PAGE_SIZE); 488 489 /* 490 * We only reuse the PGD from the swapper_pg_dir, not the pud + pmd 491 * allocated with it. 492 */ 493 memblock_free(__pa(swapper_pg_dir) + PAGE_SIZE, 494 SWAPPER_DIR_SIZE - PAGE_SIZE); 495 496 bootmem_init(); 497 } 498 499 /* 500 * Check whether a kernel address is valid (derived from arch/x86/). 501 */ 502 int kern_addr_valid(unsigned long addr) 503 { 504 pgd_t *pgd; 505 pud_t *pud; 506 pmd_t *pmd; 507 pte_t *pte; 508 509 if ((((long)addr) >> VA_BITS) != -1UL) 510 return 0; 511 512 pgd = pgd_offset_k(addr); 513 if (pgd_none(*pgd)) 514 return 0; 515 516 pud = pud_offset(pgd, addr); 517 if (pud_none(*pud)) 518 return 0; 519 520 if (pud_sect(*pud)) 521 return pfn_valid(pud_pfn(*pud)); 522 523 pmd = pmd_offset(pud, addr); 524 if (pmd_none(*pmd)) 525 return 0; 526 527 if (pmd_sect(*pmd)) 528 return pfn_valid(pmd_pfn(*pmd)); 529 530 pte = pte_offset_kernel(pmd, addr); 531 if (pte_none(*pte)) 532 return 0; 533 534 return pfn_valid(pte_pfn(*pte)); 535 } 536 #ifdef CONFIG_SPARSEMEM_VMEMMAP 537 #if !ARM64_SWAPPER_USES_SECTION_MAPS 538 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) 539 { 540 return vmemmap_populate_basepages(start, end, node); 541 } 542 #else /* !ARM64_SWAPPER_USES_SECTION_MAPS */ 543 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) 544 { 545 unsigned long addr = start; 546 unsigned long next; 547 pgd_t *pgd; 548 pud_t *pud; 549 pmd_t *pmd; 550 551 do { 552 next = pmd_addr_end(addr, end); 553 554 pgd = vmemmap_pgd_populate(addr, node); 555 if (!pgd) 556 return -ENOMEM; 557 558 pud = vmemmap_pud_populate(pgd, addr, node); 559 if (!pud) 560 return -ENOMEM; 561 562 pmd = pmd_offset(pud, addr); 563 if (pmd_none(*pmd)) { 564 void *p = NULL; 565 566 p = vmemmap_alloc_block_buf(PMD_SIZE, node); 567 if (!p) 568 return -ENOMEM; 569 570 set_pmd(pmd, __pmd(__pa(p) | PROT_SECT_NORMAL)); 571 } else 572 vmemmap_verify((pte_t *)pmd, node, addr, next); 573 } while (addr = next, addr != end); 574 575 return 0; 576 } 577 #endif /* CONFIG_ARM64_64K_PAGES */ 578 void vmemmap_free(unsigned long start, unsigned long end) 579 { 580 } 581 #endif /* CONFIG_SPARSEMEM_VMEMMAP */ 582 583 static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss; 584 #if CONFIG_PGTABLE_LEVELS > 2 585 static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss; 586 #endif 587 #if CONFIG_PGTABLE_LEVELS > 3 588 static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss; 589 #endif 590 591 static inline pud_t * fixmap_pud(unsigned long addr) 592 { 593 pgd_t *pgd = pgd_offset_k(addr); 594 595 BUG_ON(pgd_none(*pgd) || pgd_bad(*pgd)); 596 597 return pud_offset(pgd, addr); 598 } 599 600 static inline pmd_t * fixmap_pmd(unsigned long addr) 601 { 602 pud_t *pud = fixmap_pud(addr); 603 604 BUG_ON(pud_none(*pud) || pud_bad(*pud)); 605 606 return pmd_offset(pud, addr); 607 } 608 609 static inline pte_t * fixmap_pte(unsigned long addr) 610 { 611 pmd_t *pmd = fixmap_pmd(addr); 612 613 BUG_ON(pmd_none(*pmd) || pmd_bad(*pmd)); 614 615 return pte_offset_kernel(pmd, addr); 616 } 617 618 void __init early_fixmap_init(void) 619 { 620 pgd_t *pgd; 621 pud_t *pud; 622 pmd_t *pmd; 623 unsigned long addr = FIXADDR_START; 624 625 pgd = pgd_offset_k(addr); 626 pgd_populate(&init_mm, pgd, bm_pud); 627 pud = pud_offset(pgd, addr); 628 pud_populate(&init_mm, pud, bm_pmd); 629 pmd = pmd_offset(pud, addr); 630 pmd_populate_kernel(&init_mm, pmd, bm_pte); 631 632 /* 633 * The boot-ioremap range spans multiple pmds, for which 634 * we are not preparted: 635 */ 636 BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) 637 != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); 638 639 if ((pmd != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN))) 640 || pmd != fixmap_pmd(fix_to_virt(FIX_BTMAP_END))) { 641 WARN_ON(1); 642 pr_warn("pmd %p != %p, %p\n", 643 pmd, fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)), 644 fixmap_pmd(fix_to_virt(FIX_BTMAP_END))); 645 pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n", 646 fix_to_virt(FIX_BTMAP_BEGIN)); 647 pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n", 648 fix_to_virt(FIX_BTMAP_END)); 649 650 pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END); 651 pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN); 652 } 653 } 654 655 void __set_fixmap(enum fixed_addresses idx, 656 phys_addr_t phys, pgprot_t flags) 657 { 658 unsigned long addr = __fix_to_virt(idx); 659 pte_t *pte; 660 661 BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses); 662 663 pte = fixmap_pte(addr); 664 665 if (pgprot_val(flags)) { 666 set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags)); 667 } else { 668 pte_clear(&init_mm, addr, pte); 669 flush_tlb_kernel_range(addr, addr+PAGE_SIZE); 670 } 671 } 672 673 void *__init fixmap_remap_fdt(phys_addr_t dt_phys) 674 { 675 const u64 dt_virt_base = __fix_to_virt(FIX_FDT); 676 pgprot_t prot = PAGE_KERNEL_RO; 677 int size, offset; 678 void *dt_virt; 679 680 /* 681 * Check whether the physical FDT address is set and meets the minimum 682 * alignment requirement. Since we are relying on MIN_FDT_ALIGN to be 683 * at least 8 bytes so that we can always access the size field of the 684 * FDT header after mapping the first chunk, double check here if that 685 * is indeed the case. 686 */ 687 BUILD_BUG_ON(MIN_FDT_ALIGN < 8); 688 if (!dt_phys || dt_phys % MIN_FDT_ALIGN) 689 return NULL; 690 691 /* 692 * Make sure that the FDT region can be mapped without the need to 693 * allocate additional translation table pages, so that it is safe 694 * to call create_mapping_noalloc() this early. 695 * 696 * On 64k pages, the FDT will be mapped using PTEs, so we need to 697 * be in the same PMD as the rest of the fixmap. 698 * On 4k pages, we'll use section mappings for the FDT so we only 699 * have to be in the same PUD. 700 */ 701 BUILD_BUG_ON(dt_virt_base % SZ_2M); 702 703 BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != 704 __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT); 705 706 offset = dt_phys % SWAPPER_BLOCK_SIZE; 707 dt_virt = (void *)dt_virt_base + offset; 708 709 /* map the first chunk so we can read the size from the header */ 710 create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE), 711 dt_virt_base, SWAPPER_BLOCK_SIZE, prot); 712 713 if (fdt_check_header(dt_virt) != 0) 714 return NULL; 715 716 size = fdt_totalsize(dt_virt); 717 if (size > MAX_FDT_SIZE) 718 return NULL; 719 720 if (offset + size > SWAPPER_BLOCK_SIZE) 721 create_mapping_noalloc(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base, 722 round_up(offset + size, SWAPPER_BLOCK_SIZE), prot); 723 724 memblock_reserve(dt_phys, size); 725 726 return dt_virt; 727 } 728