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/cputype.h> 34 #include <asm/fixmap.h> 35 #include <asm/sections.h> 36 #include <asm/setup.h> 37 #include <asm/sizes.h> 38 #include <asm/tlb.h> 39 #include <asm/memblock.h> 40 #include <asm/mmu_context.h> 41 42 #include "mm.h" 43 44 u64 idmap_t0sz = TCR_T0SZ(VA_BITS); 45 46 /* 47 * Empty_zero_page is a special page that is used for zero-initialized data 48 * and COW. 49 */ 50 struct page *empty_zero_page; 51 EXPORT_SYMBOL(empty_zero_page); 52 53 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 54 unsigned long size, pgprot_t vma_prot) 55 { 56 if (!pfn_valid(pfn)) 57 return pgprot_noncached(vma_prot); 58 else if (file->f_flags & O_SYNC) 59 return pgprot_writecombine(vma_prot); 60 return vma_prot; 61 } 62 EXPORT_SYMBOL(phys_mem_access_prot); 63 64 static void __init *early_alloc(unsigned long sz) 65 { 66 void *ptr = __va(memblock_alloc(sz, sz)); 67 BUG_ON(!ptr); 68 memset(ptr, 0, sz); 69 return ptr; 70 } 71 72 /* 73 * remap a PMD into pages 74 */ 75 static void split_pmd(pmd_t *pmd, pte_t *pte) 76 { 77 unsigned long pfn = pmd_pfn(*pmd); 78 int i = 0; 79 80 do { 81 /* 82 * Need to have the least restrictive permissions available 83 * permissions will be fixed up later 84 */ 85 set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC)); 86 pfn++; 87 } while (pte++, i++, i < PTRS_PER_PTE); 88 } 89 90 static void alloc_init_pte(pmd_t *pmd, unsigned long addr, 91 unsigned long end, unsigned long pfn, 92 pgprot_t prot, 93 void *(*alloc)(unsigned long size)) 94 { 95 pte_t *pte; 96 97 if (pmd_none(*pmd) || pmd_sect(*pmd)) { 98 pte = alloc(PTRS_PER_PTE * sizeof(pte_t)); 99 if (pmd_sect(*pmd)) 100 split_pmd(pmd, pte); 101 __pmd_populate(pmd, __pa(pte), PMD_TYPE_TABLE); 102 flush_tlb_all(); 103 } 104 BUG_ON(pmd_bad(*pmd)); 105 106 pte = pte_offset_kernel(pmd, addr); 107 do { 108 set_pte(pte, pfn_pte(pfn, prot)); 109 pfn++; 110 } while (pte++, addr += PAGE_SIZE, addr != end); 111 } 112 113 void split_pud(pud_t *old_pud, pmd_t *pmd) 114 { 115 unsigned long addr = pud_pfn(*old_pud) << PAGE_SHIFT; 116 pgprot_t prot = __pgprot(pud_val(*old_pud) ^ addr); 117 int i = 0; 118 119 do { 120 set_pmd(pmd, __pmd(addr | pgprot_val(prot))); 121 addr += PMD_SIZE; 122 } while (pmd++, i++, i < PTRS_PER_PMD); 123 } 124 125 static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud, 126 unsigned long addr, unsigned long end, 127 phys_addr_t phys, pgprot_t prot, 128 void *(*alloc)(unsigned long size)) 129 { 130 pmd_t *pmd; 131 unsigned long next; 132 133 /* 134 * Check for initial section mappings in the pgd/pud and remove them. 135 */ 136 if (pud_none(*pud) || pud_sect(*pud)) { 137 pmd = alloc(PTRS_PER_PMD * sizeof(pmd_t)); 138 if (pud_sect(*pud)) { 139 /* 140 * need to have the 1G of mappings continue to be 141 * present 142 */ 143 split_pud(pud, pmd); 144 } 145 pud_populate(mm, pud, pmd); 146 flush_tlb_all(); 147 } 148 BUG_ON(pud_bad(*pud)); 149 150 pmd = pmd_offset(pud, addr); 151 do { 152 next = pmd_addr_end(addr, end); 153 /* try section mapping first */ 154 if (((addr | next | phys) & ~SECTION_MASK) == 0) { 155 pmd_t old_pmd =*pmd; 156 set_pmd(pmd, __pmd(phys | 157 pgprot_val(mk_sect_prot(prot)))); 158 /* 159 * Check for previous table entries created during 160 * boot (__create_page_tables) and flush them. 161 */ 162 if (!pmd_none(old_pmd)) { 163 flush_tlb_all(); 164 if (pmd_table(old_pmd)) { 165 phys_addr_t table = __pa(pte_offset_map(&old_pmd, 0)); 166 if (!WARN_ON_ONCE(slab_is_available())) 167 memblock_free(table, PAGE_SIZE); 168 } 169 } 170 } else { 171 alloc_init_pte(pmd, addr, next, __phys_to_pfn(phys), 172 prot, alloc); 173 } 174 phys += next - addr; 175 } while (pmd++, addr = next, addr != end); 176 } 177 178 static inline bool use_1G_block(unsigned long addr, unsigned long next, 179 unsigned long phys) 180 { 181 if (PAGE_SHIFT != 12) 182 return false; 183 184 if (((addr | next | phys) & ~PUD_MASK) != 0) 185 return false; 186 187 return true; 188 } 189 190 static void alloc_init_pud(struct mm_struct *mm, pgd_t *pgd, 191 unsigned long addr, unsigned long end, 192 phys_addr_t phys, pgprot_t prot, 193 void *(*alloc)(unsigned long size)) 194 { 195 pud_t *pud; 196 unsigned long next; 197 198 if (pgd_none(*pgd)) { 199 pud = alloc(PTRS_PER_PUD * sizeof(pud_t)); 200 pgd_populate(mm, pgd, pud); 201 } 202 BUG_ON(pgd_bad(*pgd)); 203 204 pud = pud_offset(pgd, addr); 205 do { 206 next = pud_addr_end(addr, end); 207 208 /* 209 * For 4K granule only, attempt to put down a 1GB block 210 */ 211 if (use_1G_block(addr, next, phys)) { 212 pud_t old_pud = *pud; 213 set_pud(pud, __pud(phys | 214 pgprot_val(mk_sect_prot(prot)))); 215 216 /* 217 * If we have an old value for a pud, it will 218 * be pointing to a pmd table that we no longer 219 * need (from swapper_pg_dir). 220 * 221 * Look up the old pmd table and free it. 222 */ 223 if (!pud_none(old_pud)) { 224 flush_tlb_all(); 225 if (pud_table(old_pud)) { 226 phys_addr_t table = __pa(pmd_offset(&old_pud, 0)); 227 if (!WARN_ON_ONCE(slab_is_available())) 228 memblock_free(table, PAGE_SIZE); 229 } 230 } 231 } else { 232 alloc_init_pmd(mm, pud, addr, next, phys, prot, alloc); 233 } 234 phys += next - addr; 235 } while (pud++, addr = next, addr != end); 236 } 237 238 /* 239 * Create the page directory entries and any necessary page tables for the 240 * mapping specified by 'md'. 241 */ 242 static void __create_mapping(struct mm_struct *mm, pgd_t *pgd, 243 phys_addr_t phys, unsigned long virt, 244 phys_addr_t size, pgprot_t prot, 245 void *(*alloc)(unsigned long size)) 246 { 247 unsigned long addr, length, end, next; 248 249 addr = virt & PAGE_MASK; 250 length = PAGE_ALIGN(size + (virt & ~PAGE_MASK)); 251 252 end = addr + length; 253 do { 254 next = pgd_addr_end(addr, end); 255 alloc_init_pud(mm, pgd, addr, next, phys, prot, alloc); 256 phys += next - addr; 257 } while (pgd++, addr = next, addr != end); 258 } 259 260 static void *late_alloc(unsigned long size) 261 { 262 void *ptr; 263 264 BUG_ON(size > PAGE_SIZE); 265 ptr = (void *)__get_free_page(PGALLOC_GFP); 266 BUG_ON(!ptr); 267 return ptr; 268 } 269 270 static void __ref create_mapping(phys_addr_t phys, unsigned long virt, 271 phys_addr_t size, pgprot_t prot) 272 { 273 if (virt < VMALLOC_START) { 274 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", 275 &phys, virt); 276 return; 277 } 278 __create_mapping(&init_mm, pgd_offset_k(virt & PAGE_MASK), phys, virt, 279 size, prot, early_alloc); 280 } 281 282 void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, 283 unsigned long virt, phys_addr_t size, 284 pgprot_t prot) 285 { 286 __create_mapping(mm, pgd_offset(mm, virt), phys, virt, size, prot, 287 late_alloc); 288 } 289 290 static void create_mapping_late(phys_addr_t phys, unsigned long virt, 291 phys_addr_t size, pgprot_t prot) 292 { 293 if (virt < VMALLOC_START) { 294 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", 295 &phys, virt); 296 return; 297 } 298 299 return __create_mapping(&init_mm, pgd_offset_k(virt & PAGE_MASK), 300 phys, virt, size, prot, late_alloc); 301 } 302 303 #ifdef CONFIG_DEBUG_RODATA 304 static void __init __map_memblock(phys_addr_t start, phys_addr_t end) 305 { 306 /* 307 * Set up the executable regions using the existing section mappings 308 * for now. This will get more fine grained later once all memory 309 * is mapped 310 */ 311 unsigned long kernel_x_start = round_down(__pa(_stext), SECTION_SIZE); 312 unsigned long kernel_x_end = round_up(__pa(__init_end), SECTION_SIZE); 313 314 if (end < kernel_x_start) { 315 create_mapping(start, __phys_to_virt(start), 316 end - start, PAGE_KERNEL); 317 } else if (start >= kernel_x_end) { 318 create_mapping(start, __phys_to_virt(start), 319 end - start, PAGE_KERNEL); 320 } else { 321 if (start < kernel_x_start) 322 create_mapping(start, __phys_to_virt(start), 323 kernel_x_start - start, 324 PAGE_KERNEL); 325 create_mapping(kernel_x_start, 326 __phys_to_virt(kernel_x_start), 327 kernel_x_end - kernel_x_start, 328 PAGE_KERNEL_EXEC); 329 if (kernel_x_end < end) 330 create_mapping(kernel_x_end, 331 __phys_to_virt(kernel_x_end), 332 end - kernel_x_end, 333 PAGE_KERNEL); 334 } 335 336 } 337 #else 338 static void __init __map_memblock(phys_addr_t start, phys_addr_t end) 339 { 340 create_mapping(start, __phys_to_virt(start), end - start, 341 PAGE_KERNEL_EXEC); 342 } 343 #endif 344 345 static void __init map_mem(void) 346 { 347 struct memblock_region *reg; 348 phys_addr_t limit; 349 350 /* 351 * Temporarily limit the memblock range. We need to do this as 352 * create_mapping requires puds, pmds and ptes to be allocated from 353 * memory addressable from the initial direct kernel mapping. 354 * 355 * The initial direct kernel mapping, located at swapper_pg_dir, gives 356 * us PUD_SIZE (4K pages) or PMD_SIZE (64K pages) memory starting from 357 * PHYS_OFFSET (which must be aligned to 2MB as per 358 * Documentation/arm64/booting.txt). 359 */ 360 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) 361 limit = PHYS_OFFSET + PMD_SIZE; 362 else 363 limit = PHYS_OFFSET + PUD_SIZE; 364 memblock_set_current_limit(limit); 365 366 /* map all the memory banks */ 367 for_each_memblock(memory, reg) { 368 phys_addr_t start = reg->base; 369 phys_addr_t end = start + reg->size; 370 371 if (start >= end) 372 break; 373 374 #ifndef CONFIG_ARM64_64K_PAGES 375 /* 376 * For the first memory bank align the start address and 377 * current memblock limit to prevent create_mapping() from 378 * allocating pte page tables from unmapped memory. 379 * When 64K pages are enabled, the pte page table for the 380 * first PGDIR_SIZE is already present in swapper_pg_dir. 381 */ 382 if (start < limit) 383 start = ALIGN(start, PMD_SIZE); 384 if (end < limit) { 385 limit = end & PMD_MASK; 386 memblock_set_current_limit(limit); 387 } 388 #endif 389 __map_memblock(start, end); 390 } 391 392 /* Limit no longer required. */ 393 memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE); 394 } 395 396 void __init fixup_executable(void) 397 { 398 #ifdef CONFIG_DEBUG_RODATA 399 /* now that we are actually fully mapped, make the start/end more fine grained */ 400 if (!IS_ALIGNED((unsigned long)_stext, SECTION_SIZE)) { 401 unsigned long aligned_start = round_down(__pa(_stext), 402 SECTION_SIZE); 403 404 create_mapping(aligned_start, __phys_to_virt(aligned_start), 405 __pa(_stext) - aligned_start, 406 PAGE_KERNEL); 407 } 408 409 if (!IS_ALIGNED((unsigned long)__init_end, SECTION_SIZE)) { 410 unsigned long aligned_end = round_up(__pa(__init_end), 411 SECTION_SIZE); 412 create_mapping(__pa(__init_end), (unsigned long)__init_end, 413 aligned_end - __pa(__init_end), 414 PAGE_KERNEL); 415 } 416 #endif 417 } 418 419 #ifdef CONFIG_DEBUG_RODATA 420 void mark_rodata_ro(void) 421 { 422 create_mapping_late(__pa(_stext), (unsigned long)_stext, 423 (unsigned long)_etext - (unsigned long)_stext, 424 PAGE_KERNEL_EXEC | PTE_RDONLY); 425 426 } 427 #endif 428 429 void fixup_init(void) 430 { 431 create_mapping_late(__pa(__init_begin), (unsigned long)__init_begin, 432 (unsigned long)__init_end - (unsigned long)__init_begin, 433 PAGE_KERNEL); 434 } 435 436 /* 437 * paging_init() sets up the page tables, initialises the zone memory 438 * maps and sets up the zero page. 439 */ 440 void __init paging_init(void) 441 { 442 void *zero_page; 443 444 map_mem(); 445 fixup_executable(); 446 447 /* allocate the zero page. */ 448 zero_page = early_alloc(PAGE_SIZE); 449 450 bootmem_init(); 451 452 empty_zero_page = virt_to_page(zero_page); 453 454 /* 455 * TTBR0 is only used for the identity mapping at this stage. Make it 456 * point to zero page to avoid speculatively fetching new entries. 457 */ 458 cpu_set_reserved_ttbr0(); 459 flush_tlb_all(); 460 cpu_set_default_tcr_t0sz(); 461 } 462 463 /* 464 * Enable the identity mapping to allow the MMU disabling. 465 */ 466 void setup_mm_for_reboot(void) 467 { 468 cpu_set_reserved_ttbr0(); 469 flush_tlb_all(); 470 cpu_set_idmap_tcr_t0sz(); 471 cpu_switch_mm(idmap_pg_dir, &init_mm); 472 } 473 474 /* 475 * Check whether a kernel address is valid (derived from arch/x86/). 476 */ 477 int kern_addr_valid(unsigned long addr) 478 { 479 pgd_t *pgd; 480 pud_t *pud; 481 pmd_t *pmd; 482 pte_t *pte; 483 484 if ((((long)addr) >> VA_BITS) != -1UL) 485 return 0; 486 487 pgd = pgd_offset_k(addr); 488 if (pgd_none(*pgd)) 489 return 0; 490 491 pud = pud_offset(pgd, addr); 492 if (pud_none(*pud)) 493 return 0; 494 495 if (pud_sect(*pud)) 496 return pfn_valid(pud_pfn(*pud)); 497 498 pmd = pmd_offset(pud, addr); 499 if (pmd_none(*pmd)) 500 return 0; 501 502 if (pmd_sect(*pmd)) 503 return pfn_valid(pmd_pfn(*pmd)); 504 505 pte = pte_offset_kernel(pmd, addr); 506 if (pte_none(*pte)) 507 return 0; 508 509 return pfn_valid(pte_pfn(*pte)); 510 } 511 #ifdef CONFIG_SPARSEMEM_VMEMMAP 512 #ifdef CONFIG_ARM64_64K_PAGES 513 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) 514 { 515 return vmemmap_populate_basepages(start, end, node); 516 } 517 #else /* !CONFIG_ARM64_64K_PAGES */ 518 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) 519 { 520 unsigned long addr = start; 521 unsigned long next; 522 pgd_t *pgd; 523 pud_t *pud; 524 pmd_t *pmd; 525 526 do { 527 next = pmd_addr_end(addr, end); 528 529 pgd = vmemmap_pgd_populate(addr, node); 530 if (!pgd) 531 return -ENOMEM; 532 533 pud = vmemmap_pud_populate(pgd, addr, node); 534 if (!pud) 535 return -ENOMEM; 536 537 pmd = pmd_offset(pud, addr); 538 if (pmd_none(*pmd)) { 539 void *p = NULL; 540 541 p = vmemmap_alloc_block_buf(PMD_SIZE, node); 542 if (!p) 543 return -ENOMEM; 544 545 set_pmd(pmd, __pmd(__pa(p) | PROT_SECT_NORMAL)); 546 } else 547 vmemmap_verify((pte_t *)pmd, node, addr, next); 548 } while (addr = next, addr != end); 549 550 return 0; 551 } 552 #endif /* CONFIG_ARM64_64K_PAGES */ 553 void vmemmap_free(unsigned long start, unsigned long end) 554 { 555 } 556 #endif /* CONFIG_SPARSEMEM_VMEMMAP */ 557 558 static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss; 559 #if CONFIG_PGTABLE_LEVELS > 2 560 static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss; 561 #endif 562 #if CONFIG_PGTABLE_LEVELS > 3 563 static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss; 564 #endif 565 566 static inline pud_t * fixmap_pud(unsigned long addr) 567 { 568 pgd_t *pgd = pgd_offset_k(addr); 569 570 BUG_ON(pgd_none(*pgd) || pgd_bad(*pgd)); 571 572 return pud_offset(pgd, addr); 573 } 574 575 static inline pmd_t * fixmap_pmd(unsigned long addr) 576 { 577 pud_t *pud = fixmap_pud(addr); 578 579 BUG_ON(pud_none(*pud) || pud_bad(*pud)); 580 581 return pmd_offset(pud, addr); 582 } 583 584 static inline pte_t * fixmap_pte(unsigned long addr) 585 { 586 pmd_t *pmd = fixmap_pmd(addr); 587 588 BUG_ON(pmd_none(*pmd) || pmd_bad(*pmd)); 589 590 return pte_offset_kernel(pmd, addr); 591 } 592 593 void __init early_fixmap_init(void) 594 { 595 pgd_t *pgd; 596 pud_t *pud; 597 pmd_t *pmd; 598 unsigned long addr = FIXADDR_START; 599 600 pgd = pgd_offset_k(addr); 601 pgd_populate(&init_mm, pgd, bm_pud); 602 pud = pud_offset(pgd, addr); 603 pud_populate(&init_mm, pud, bm_pmd); 604 pmd = pmd_offset(pud, addr); 605 pmd_populate_kernel(&init_mm, pmd, bm_pte); 606 607 /* 608 * The boot-ioremap range spans multiple pmds, for which 609 * we are not preparted: 610 */ 611 BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) 612 != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); 613 614 if ((pmd != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN))) 615 || pmd != fixmap_pmd(fix_to_virt(FIX_BTMAP_END))) { 616 WARN_ON(1); 617 pr_warn("pmd %p != %p, %p\n", 618 pmd, fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)), 619 fixmap_pmd(fix_to_virt(FIX_BTMAP_END))); 620 pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n", 621 fix_to_virt(FIX_BTMAP_BEGIN)); 622 pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n", 623 fix_to_virt(FIX_BTMAP_END)); 624 625 pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END); 626 pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN); 627 } 628 } 629 630 void __set_fixmap(enum fixed_addresses idx, 631 phys_addr_t phys, pgprot_t flags) 632 { 633 unsigned long addr = __fix_to_virt(idx); 634 pte_t *pte; 635 636 BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses); 637 638 pte = fixmap_pte(addr); 639 640 if (pgprot_val(flags)) { 641 set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags)); 642 } else { 643 pte_clear(&init_mm, addr, pte); 644 flush_tlb_kernel_range(addr, addr+PAGE_SIZE); 645 } 646 } 647 648 void *__init fixmap_remap_fdt(phys_addr_t dt_phys) 649 { 650 const u64 dt_virt_base = __fix_to_virt(FIX_FDT); 651 pgprot_t prot = PAGE_KERNEL | PTE_RDONLY; 652 int granularity, size, offset; 653 void *dt_virt; 654 655 /* 656 * Check whether the physical FDT address is set and meets the minimum 657 * alignment requirement. Since we are relying on MIN_FDT_ALIGN to be 658 * at least 8 bytes so that we can always access the size field of the 659 * FDT header after mapping the first chunk, double check here if that 660 * is indeed the case. 661 */ 662 BUILD_BUG_ON(MIN_FDT_ALIGN < 8); 663 if (!dt_phys || dt_phys % MIN_FDT_ALIGN) 664 return NULL; 665 666 /* 667 * Make sure that the FDT region can be mapped without the need to 668 * allocate additional translation table pages, so that it is safe 669 * to call create_mapping() this early. 670 * 671 * On 64k pages, the FDT will be mapped using PTEs, so we need to 672 * be in the same PMD as the rest of the fixmap. 673 * On 4k pages, we'll use section mappings for the FDT so we only 674 * have to be in the same PUD. 675 */ 676 BUILD_BUG_ON(dt_virt_base % SZ_2M); 677 678 if (IS_ENABLED(CONFIG_ARM64_64K_PAGES)) { 679 BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> PMD_SHIFT != 680 __fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT); 681 682 granularity = PAGE_SIZE; 683 } else { 684 BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> PUD_SHIFT != 685 __fix_to_virt(FIX_BTMAP_BEGIN) >> PUD_SHIFT); 686 687 granularity = PMD_SIZE; 688 } 689 690 offset = dt_phys % granularity; 691 dt_virt = (void *)dt_virt_base + offset; 692 693 /* map the first chunk so we can read the size from the header */ 694 create_mapping(round_down(dt_phys, granularity), dt_virt_base, 695 granularity, prot); 696 697 if (fdt_check_header(dt_virt) != 0) 698 return NULL; 699 700 size = fdt_totalsize(dt_virt); 701 if (size > MAX_FDT_SIZE) 702 return NULL; 703 704 if (offset + size > granularity) 705 create_mapping(round_down(dt_phys, granularity), dt_virt_base, 706 round_up(offset + size, granularity), prot); 707 708 memblock_reserve(dt_phys, size); 709 710 return dt_virt; 711 } 712