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/kernel-pgtable.h> 36 #include <asm/sections.h> 37 #include <asm/setup.h> 38 #include <asm/sizes.h> 39 #include <asm/tlb.h> 40 #include <asm/memblock.h> 41 #include <asm/mmu_context.h> 42 43 #include "mm.h" 44 45 u64 idmap_t0sz = TCR_T0SZ(VA_BITS); 46 47 /* 48 * Empty_zero_page is a special page that is used for zero-initialized data 49 * and COW. 50 */ 51 struct page *empty_zero_page; 52 EXPORT_SYMBOL(empty_zero_page); 53 54 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, 55 unsigned long size, pgprot_t vma_prot) 56 { 57 if (!pfn_valid(pfn)) 58 return pgprot_noncached(vma_prot); 59 else if (file->f_flags & O_SYNC) 60 return pgprot_writecombine(vma_prot); 61 return vma_prot; 62 } 63 EXPORT_SYMBOL(phys_mem_access_prot); 64 65 static void __init *early_alloc(unsigned long sz) 66 { 67 void *ptr = __va(memblock_alloc(sz, sz)); 68 BUG_ON(!ptr); 69 memset(ptr, 0, sz); 70 return ptr; 71 } 72 73 /* 74 * remap a PMD into pages 75 */ 76 static void split_pmd(pmd_t *pmd, pte_t *pte) 77 { 78 unsigned long pfn = pmd_pfn(*pmd); 79 int i = 0; 80 81 do { 82 /* 83 * Need to have the least restrictive permissions available 84 * permissions will be fixed up later. Default the new page 85 * range as contiguous ptes. 86 */ 87 set_pte(pte, pfn_pte(pfn, PAGE_KERNEL_EXEC_CONT)); 88 pfn++; 89 } while (pte++, i++, i < PTRS_PER_PTE); 90 } 91 92 /* 93 * Given a PTE with the CONT bit set, determine where the CONT range 94 * starts, and clear the entire range of PTE CONT bits. 95 */ 96 static void clear_cont_pte_range(pte_t *pte, unsigned long addr) 97 { 98 int i; 99 100 pte -= CONT_RANGE_OFFSET(addr); 101 for (i = 0; i < CONT_PTES; i++) { 102 set_pte(pte, pte_mknoncont(*pte)); 103 pte++; 104 } 105 flush_tlb_all(); 106 } 107 108 /* 109 * Given a range of PTEs set the pfn and provided page protection flags 110 */ 111 static void __populate_init_pte(pte_t *pte, unsigned long addr, 112 unsigned long end, phys_addr_t phys, 113 pgprot_t prot) 114 { 115 unsigned long pfn = __phys_to_pfn(phys); 116 117 do { 118 /* clear all the bits except the pfn, then apply the prot */ 119 set_pte(pte, pfn_pte(pfn, prot)); 120 pte++; 121 pfn++; 122 addr += PAGE_SIZE; 123 } while (addr != end); 124 } 125 126 static void alloc_init_pte(pmd_t *pmd, unsigned long addr, 127 unsigned long end, phys_addr_t phys, 128 pgprot_t prot, 129 void *(*alloc)(unsigned long size)) 130 { 131 pte_t *pte; 132 unsigned long next; 133 134 if (pmd_none(*pmd) || pmd_sect(*pmd)) { 135 pte = alloc(PTRS_PER_PTE * sizeof(pte_t)); 136 if (pmd_sect(*pmd)) 137 split_pmd(pmd, pte); 138 __pmd_populate(pmd, __pa(pte), PMD_TYPE_TABLE); 139 flush_tlb_all(); 140 } 141 BUG_ON(pmd_bad(*pmd)); 142 143 pte = pte_offset_kernel(pmd, addr); 144 do { 145 next = min(end, (addr + CONT_SIZE) & CONT_MASK); 146 if (((addr | next | phys) & ~CONT_MASK) == 0) { 147 /* a block of CONT_PTES */ 148 __populate_init_pte(pte, addr, next, phys, 149 __pgprot(pgprot_val(prot) | PTE_CONT)); 150 } else { 151 /* 152 * If the range being split is already inside of a 153 * contiguous range but this PTE isn't going to be 154 * contiguous, then we want to unmark the adjacent 155 * ranges, then update the portion of the range we 156 * are interrested in. 157 */ 158 clear_cont_pte_range(pte, addr); 159 __populate_init_pte(pte, addr, next, phys, prot); 160 } 161 162 pte += (next - addr) >> PAGE_SHIFT; 163 phys += next - addr; 164 addr = next; 165 } while (addr != end); 166 } 167 168 static void split_pud(pud_t *old_pud, pmd_t *pmd) 169 { 170 unsigned long addr = pud_pfn(*old_pud) << PAGE_SHIFT; 171 pgprot_t prot = __pgprot(pud_val(*old_pud) ^ addr); 172 int i = 0; 173 174 do { 175 set_pmd(pmd, __pmd(addr | pgprot_val(prot))); 176 addr += PMD_SIZE; 177 } while (pmd++, i++, i < PTRS_PER_PMD); 178 } 179 180 static void alloc_init_pmd(struct mm_struct *mm, pud_t *pud, 181 unsigned long addr, unsigned long end, 182 phys_addr_t phys, pgprot_t prot, 183 void *(*alloc)(unsigned long size)) 184 { 185 pmd_t *pmd; 186 unsigned long next; 187 188 /* 189 * Check for initial section mappings in the pgd/pud and remove them. 190 */ 191 if (pud_none(*pud) || pud_sect(*pud)) { 192 pmd = alloc(PTRS_PER_PMD * sizeof(pmd_t)); 193 if (pud_sect(*pud)) { 194 /* 195 * need to have the 1G of mappings continue to be 196 * present 197 */ 198 split_pud(pud, pmd); 199 } 200 pud_populate(mm, pud, pmd); 201 flush_tlb_all(); 202 } 203 BUG_ON(pud_bad(*pud)); 204 205 pmd = pmd_offset(pud, addr); 206 do { 207 next = pmd_addr_end(addr, end); 208 /* try section mapping first */ 209 if (((addr | next | phys) & ~SECTION_MASK) == 0) { 210 pmd_t old_pmd =*pmd; 211 set_pmd(pmd, __pmd(phys | 212 pgprot_val(mk_sect_prot(prot)))); 213 /* 214 * Check for previous table entries created during 215 * boot (__create_page_tables) and flush them. 216 */ 217 if (!pmd_none(old_pmd)) { 218 flush_tlb_all(); 219 if (pmd_table(old_pmd)) { 220 phys_addr_t table = __pa(pte_offset_map(&old_pmd, 0)); 221 if (!WARN_ON_ONCE(slab_is_available())) 222 memblock_free(table, PAGE_SIZE); 223 } 224 } 225 } else { 226 alloc_init_pte(pmd, addr, next, phys, prot, alloc); 227 } 228 phys += next - addr; 229 } while (pmd++, addr = next, addr != end); 230 } 231 232 static inline bool use_1G_block(unsigned long addr, unsigned long next, 233 unsigned long phys) 234 { 235 if (PAGE_SHIFT != 12) 236 return false; 237 238 if (((addr | next | phys) & ~PUD_MASK) != 0) 239 return false; 240 241 return true; 242 } 243 244 static void alloc_init_pud(struct mm_struct *mm, pgd_t *pgd, 245 unsigned long addr, unsigned long end, 246 phys_addr_t phys, pgprot_t prot, 247 void *(*alloc)(unsigned long size)) 248 { 249 pud_t *pud; 250 unsigned long next; 251 252 if (pgd_none(*pgd)) { 253 pud = alloc(PTRS_PER_PUD * sizeof(pud_t)); 254 pgd_populate(mm, pgd, pud); 255 } 256 BUG_ON(pgd_bad(*pgd)); 257 258 pud = pud_offset(pgd, addr); 259 do { 260 next = pud_addr_end(addr, end); 261 262 /* 263 * For 4K granule only, attempt to put down a 1GB block 264 */ 265 if (use_1G_block(addr, next, phys)) { 266 pud_t old_pud = *pud; 267 set_pud(pud, __pud(phys | 268 pgprot_val(mk_sect_prot(prot)))); 269 270 /* 271 * If we have an old value for a pud, it will 272 * be pointing to a pmd table that we no longer 273 * need (from swapper_pg_dir). 274 * 275 * Look up the old pmd table and free it. 276 */ 277 if (!pud_none(old_pud)) { 278 flush_tlb_all(); 279 if (pud_table(old_pud)) { 280 phys_addr_t table = __pa(pmd_offset(&old_pud, 0)); 281 if (!WARN_ON_ONCE(slab_is_available())) 282 memblock_free(table, PAGE_SIZE); 283 } 284 } 285 } else { 286 alloc_init_pmd(mm, pud, addr, next, phys, prot, alloc); 287 } 288 phys += next - addr; 289 } while (pud++, addr = next, addr != end); 290 } 291 292 /* 293 * Create the page directory entries and any necessary page tables for the 294 * mapping specified by 'md'. 295 */ 296 static void __create_mapping(struct mm_struct *mm, pgd_t *pgd, 297 phys_addr_t phys, unsigned long virt, 298 phys_addr_t size, pgprot_t prot, 299 void *(*alloc)(unsigned long size)) 300 { 301 unsigned long addr, length, end, next; 302 303 addr = virt & PAGE_MASK; 304 length = PAGE_ALIGN(size + (virt & ~PAGE_MASK)); 305 306 end = addr + length; 307 do { 308 next = pgd_addr_end(addr, end); 309 alloc_init_pud(mm, pgd, addr, next, phys, prot, alloc); 310 phys += next - addr; 311 } while (pgd++, addr = next, addr != end); 312 } 313 314 static void *late_alloc(unsigned long size) 315 { 316 void *ptr; 317 318 BUG_ON(size > PAGE_SIZE); 319 ptr = (void *)__get_free_page(PGALLOC_GFP); 320 BUG_ON(!ptr); 321 return ptr; 322 } 323 324 static void __init create_mapping(phys_addr_t phys, unsigned long virt, 325 phys_addr_t size, pgprot_t prot) 326 { 327 if (virt < VMALLOC_START) { 328 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", 329 &phys, virt); 330 return; 331 } 332 __create_mapping(&init_mm, pgd_offset_k(virt & PAGE_MASK), phys, virt, 333 size, prot, early_alloc); 334 } 335 336 void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, 337 unsigned long virt, phys_addr_t size, 338 pgprot_t prot) 339 { 340 __create_mapping(mm, pgd_offset(mm, virt), phys, virt, size, prot, 341 late_alloc); 342 } 343 344 static void create_mapping_late(phys_addr_t phys, unsigned long virt, 345 phys_addr_t size, pgprot_t prot) 346 { 347 if (virt < VMALLOC_START) { 348 pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n", 349 &phys, virt); 350 return; 351 } 352 353 return __create_mapping(&init_mm, pgd_offset_k(virt & PAGE_MASK), 354 phys, virt, size, prot, late_alloc); 355 } 356 357 #ifdef CONFIG_DEBUG_RODATA 358 static void __init __map_memblock(phys_addr_t start, phys_addr_t end) 359 { 360 /* 361 * Set up the executable regions using the existing section mappings 362 * for now. This will get more fine grained later once all memory 363 * is mapped 364 */ 365 unsigned long kernel_x_start = round_down(__pa(_stext), SWAPPER_BLOCK_SIZE); 366 unsigned long kernel_x_end = round_up(__pa(__init_end), SWAPPER_BLOCK_SIZE); 367 368 if (end < kernel_x_start) { 369 create_mapping(start, __phys_to_virt(start), 370 end - start, PAGE_KERNEL); 371 } else if (start >= kernel_x_end) { 372 create_mapping(start, __phys_to_virt(start), 373 end - start, PAGE_KERNEL); 374 } else { 375 if (start < kernel_x_start) 376 create_mapping(start, __phys_to_virt(start), 377 kernel_x_start - start, 378 PAGE_KERNEL); 379 create_mapping(kernel_x_start, 380 __phys_to_virt(kernel_x_start), 381 kernel_x_end - kernel_x_start, 382 PAGE_KERNEL_EXEC); 383 if (kernel_x_end < end) 384 create_mapping(kernel_x_end, 385 __phys_to_virt(kernel_x_end), 386 end - kernel_x_end, 387 PAGE_KERNEL); 388 } 389 390 } 391 #else 392 static void __init __map_memblock(phys_addr_t start, phys_addr_t end) 393 { 394 create_mapping(start, __phys_to_virt(start), end - start, 395 PAGE_KERNEL_EXEC); 396 } 397 #endif 398 399 static void __init map_mem(void) 400 { 401 struct memblock_region *reg; 402 phys_addr_t limit; 403 404 /* 405 * Temporarily limit the memblock range. We need to do this as 406 * create_mapping requires puds, pmds and ptes to be allocated from 407 * memory addressable from the initial direct kernel mapping. 408 * 409 * The initial direct kernel mapping, located at swapper_pg_dir, gives 410 * us PUD_SIZE (with SECTION maps) or PMD_SIZE (without SECTION maps, 411 * memory starting from PHYS_OFFSET (which must be aligned to 2MB as 412 * per Documentation/arm64/booting.txt). 413 */ 414 limit = PHYS_OFFSET + SWAPPER_INIT_MAP_SIZE; 415 memblock_set_current_limit(limit); 416 417 /* map all the memory banks */ 418 for_each_memblock(memory, reg) { 419 phys_addr_t start = reg->base; 420 phys_addr_t end = start + reg->size; 421 422 if (start >= end) 423 break; 424 425 if (ARM64_SWAPPER_USES_SECTION_MAPS) { 426 /* 427 * For the first memory bank align the start address and 428 * current memblock limit to prevent create_mapping() from 429 * allocating pte page tables from unmapped memory. With 430 * the section maps, if the first block doesn't end on section 431 * size boundary, create_mapping() will try to allocate a pte 432 * page, which may be returned from an unmapped area. 433 * When section maps are not used, the pte page table for the 434 * current limit is already present in swapper_pg_dir. 435 */ 436 if (start < limit) 437 start = ALIGN(start, SECTION_SIZE); 438 if (end < limit) { 439 limit = end & SECTION_MASK; 440 memblock_set_current_limit(limit); 441 } 442 } 443 __map_memblock(start, end); 444 } 445 446 /* Limit no longer required. */ 447 memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE); 448 } 449 450 static void __init fixup_executable(void) 451 { 452 #ifdef CONFIG_DEBUG_RODATA 453 /* now that we are actually fully mapped, make the start/end more fine grained */ 454 if (!IS_ALIGNED((unsigned long)_stext, SWAPPER_BLOCK_SIZE)) { 455 unsigned long aligned_start = round_down(__pa(_stext), 456 SWAPPER_BLOCK_SIZE); 457 458 create_mapping(aligned_start, __phys_to_virt(aligned_start), 459 __pa(_stext) - aligned_start, 460 PAGE_KERNEL); 461 } 462 463 if (!IS_ALIGNED((unsigned long)__init_end, SWAPPER_BLOCK_SIZE)) { 464 unsigned long aligned_end = round_up(__pa(__init_end), 465 SWAPPER_BLOCK_SIZE); 466 create_mapping(__pa(__init_end), (unsigned long)__init_end, 467 aligned_end - __pa(__init_end), 468 PAGE_KERNEL); 469 } 470 #endif 471 } 472 473 #ifdef CONFIG_DEBUG_RODATA 474 void mark_rodata_ro(void) 475 { 476 create_mapping_late(__pa(_stext), (unsigned long)_stext, 477 (unsigned long)_etext - (unsigned long)_stext, 478 PAGE_KERNEL_ROX); 479 480 } 481 #endif 482 483 void fixup_init(void) 484 { 485 create_mapping_late(__pa(__init_begin), (unsigned long)__init_begin, 486 (unsigned long)__init_end - (unsigned long)__init_begin, 487 PAGE_KERNEL); 488 } 489 490 /* 491 * paging_init() sets up the page tables, initialises the zone memory 492 * maps and sets up the zero page. 493 */ 494 void __init paging_init(void) 495 { 496 void *zero_page; 497 498 map_mem(); 499 fixup_executable(); 500 501 /* allocate the zero page. */ 502 zero_page = early_alloc(PAGE_SIZE); 503 504 bootmem_init(); 505 506 empty_zero_page = virt_to_page(zero_page); 507 508 /* 509 * TTBR0 is only used for the identity mapping at this stage. Make it 510 * point to zero page to avoid speculatively fetching new entries. 511 */ 512 cpu_set_reserved_ttbr0(); 513 local_flush_tlb_all(); 514 cpu_set_default_tcr_t0sz(); 515 } 516 517 /* 518 * Check whether a kernel address is valid (derived from arch/x86/). 519 */ 520 int kern_addr_valid(unsigned long addr) 521 { 522 pgd_t *pgd; 523 pud_t *pud; 524 pmd_t *pmd; 525 pte_t *pte; 526 527 if ((((long)addr) >> VA_BITS) != -1UL) 528 return 0; 529 530 pgd = pgd_offset_k(addr); 531 if (pgd_none(*pgd)) 532 return 0; 533 534 pud = pud_offset(pgd, addr); 535 if (pud_none(*pud)) 536 return 0; 537 538 if (pud_sect(*pud)) 539 return pfn_valid(pud_pfn(*pud)); 540 541 pmd = pmd_offset(pud, addr); 542 if (pmd_none(*pmd)) 543 return 0; 544 545 if (pmd_sect(*pmd)) 546 return pfn_valid(pmd_pfn(*pmd)); 547 548 pte = pte_offset_kernel(pmd, addr); 549 if (pte_none(*pte)) 550 return 0; 551 552 return pfn_valid(pte_pfn(*pte)); 553 } 554 #ifdef CONFIG_SPARSEMEM_VMEMMAP 555 #if !ARM64_SWAPPER_USES_SECTION_MAPS 556 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) 557 { 558 return vmemmap_populate_basepages(start, end, node); 559 } 560 #else /* !ARM64_SWAPPER_USES_SECTION_MAPS */ 561 int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node) 562 { 563 unsigned long addr = start; 564 unsigned long next; 565 pgd_t *pgd; 566 pud_t *pud; 567 pmd_t *pmd; 568 569 do { 570 next = pmd_addr_end(addr, end); 571 572 pgd = vmemmap_pgd_populate(addr, node); 573 if (!pgd) 574 return -ENOMEM; 575 576 pud = vmemmap_pud_populate(pgd, addr, node); 577 if (!pud) 578 return -ENOMEM; 579 580 pmd = pmd_offset(pud, addr); 581 if (pmd_none(*pmd)) { 582 void *p = NULL; 583 584 p = vmemmap_alloc_block_buf(PMD_SIZE, node); 585 if (!p) 586 return -ENOMEM; 587 588 set_pmd(pmd, __pmd(__pa(p) | PROT_SECT_NORMAL)); 589 } else 590 vmemmap_verify((pte_t *)pmd, node, addr, next); 591 } while (addr = next, addr != end); 592 593 return 0; 594 } 595 #endif /* CONFIG_ARM64_64K_PAGES */ 596 void vmemmap_free(unsigned long start, unsigned long end) 597 { 598 } 599 #endif /* CONFIG_SPARSEMEM_VMEMMAP */ 600 601 static pte_t bm_pte[PTRS_PER_PTE] __page_aligned_bss; 602 #if CONFIG_PGTABLE_LEVELS > 2 603 static pmd_t bm_pmd[PTRS_PER_PMD] __page_aligned_bss; 604 #endif 605 #if CONFIG_PGTABLE_LEVELS > 3 606 static pud_t bm_pud[PTRS_PER_PUD] __page_aligned_bss; 607 #endif 608 609 static inline pud_t * fixmap_pud(unsigned long addr) 610 { 611 pgd_t *pgd = pgd_offset_k(addr); 612 613 BUG_ON(pgd_none(*pgd) || pgd_bad(*pgd)); 614 615 return pud_offset(pgd, addr); 616 } 617 618 static inline pmd_t * fixmap_pmd(unsigned long addr) 619 { 620 pud_t *pud = fixmap_pud(addr); 621 622 BUG_ON(pud_none(*pud) || pud_bad(*pud)); 623 624 return pmd_offset(pud, addr); 625 } 626 627 static inline pte_t * fixmap_pte(unsigned long addr) 628 { 629 pmd_t *pmd = fixmap_pmd(addr); 630 631 BUG_ON(pmd_none(*pmd) || pmd_bad(*pmd)); 632 633 return pte_offset_kernel(pmd, addr); 634 } 635 636 void __init early_fixmap_init(void) 637 { 638 pgd_t *pgd; 639 pud_t *pud; 640 pmd_t *pmd; 641 unsigned long addr = FIXADDR_START; 642 643 pgd = pgd_offset_k(addr); 644 pgd_populate(&init_mm, pgd, bm_pud); 645 pud = pud_offset(pgd, addr); 646 pud_populate(&init_mm, pud, bm_pmd); 647 pmd = pmd_offset(pud, addr); 648 pmd_populate_kernel(&init_mm, pmd, bm_pte); 649 650 /* 651 * The boot-ioremap range spans multiple pmds, for which 652 * we are not preparted: 653 */ 654 BUILD_BUG_ON((__fix_to_virt(FIX_BTMAP_BEGIN) >> PMD_SHIFT) 655 != (__fix_to_virt(FIX_BTMAP_END) >> PMD_SHIFT)); 656 657 if ((pmd != fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN))) 658 || pmd != fixmap_pmd(fix_to_virt(FIX_BTMAP_END))) { 659 WARN_ON(1); 660 pr_warn("pmd %p != %p, %p\n", 661 pmd, fixmap_pmd(fix_to_virt(FIX_BTMAP_BEGIN)), 662 fixmap_pmd(fix_to_virt(FIX_BTMAP_END))); 663 pr_warn("fix_to_virt(FIX_BTMAP_BEGIN): %08lx\n", 664 fix_to_virt(FIX_BTMAP_BEGIN)); 665 pr_warn("fix_to_virt(FIX_BTMAP_END): %08lx\n", 666 fix_to_virt(FIX_BTMAP_END)); 667 668 pr_warn("FIX_BTMAP_END: %d\n", FIX_BTMAP_END); 669 pr_warn("FIX_BTMAP_BEGIN: %d\n", FIX_BTMAP_BEGIN); 670 } 671 } 672 673 void __set_fixmap(enum fixed_addresses idx, 674 phys_addr_t phys, pgprot_t flags) 675 { 676 unsigned long addr = __fix_to_virt(idx); 677 pte_t *pte; 678 679 BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses); 680 681 pte = fixmap_pte(addr); 682 683 if (pgprot_val(flags)) { 684 set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags)); 685 } else { 686 pte_clear(&init_mm, addr, pte); 687 flush_tlb_kernel_range(addr, addr+PAGE_SIZE); 688 } 689 } 690 691 void *__init fixmap_remap_fdt(phys_addr_t dt_phys) 692 { 693 const u64 dt_virt_base = __fix_to_virt(FIX_FDT); 694 pgprot_t prot = PAGE_KERNEL_RO; 695 int size, offset; 696 void *dt_virt; 697 698 /* 699 * Check whether the physical FDT address is set and meets the minimum 700 * alignment requirement. Since we are relying on MIN_FDT_ALIGN to be 701 * at least 8 bytes so that we can always access the size field of the 702 * FDT header after mapping the first chunk, double check here if that 703 * is indeed the case. 704 */ 705 BUILD_BUG_ON(MIN_FDT_ALIGN < 8); 706 if (!dt_phys || dt_phys % MIN_FDT_ALIGN) 707 return NULL; 708 709 /* 710 * Make sure that the FDT region can be mapped without the need to 711 * allocate additional translation table pages, so that it is safe 712 * to call create_mapping() this early. 713 * 714 * On 64k pages, the FDT will be mapped using PTEs, so we need to 715 * be in the same PMD as the rest of the fixmap. 716 * On 4k pages, we'll use section mappings for the FDT so we only 717 * have to be in the same PUD. 718 */ 719 BUILD_BUG_ON(dt_virt_base % SZ_2M); 720 721 BUILD_BUG_ON(__fix_to_virt(FIX_FDT_END) >> SWAPPER_TABLE_SHIFT != 722 __fix_to_virt(FIX_BTMAP_BEGIN) >> SWAPPER_TABLE_SHIFT); 723 724 offset = dt_phys % SWAPPER_BLOCK_SIZE; 725 dt_virt = (void *)dt_virt_base + offset; 726 727 /* map the first chunk so we can read the size from the header */ 728 create_mapping(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base, 729 SWAPPER_BLOCK_SIZE, prot); 730 731 if (fdt_check_header(dt_virt) != 0) 732 return NULL; 733 734 size = fdt_totalsize(dt_virt); 735 if (size > MAX_FDT_SIZE) 736 return NULL; 737 738 if (offset + size > SWAPPER_BLOCK_SIZE) 739 create_mapping(round_down(dt_phys, SWAPPER_BLOCK_SIZE), dt_virt_base, 740 round_up(offset + size, SWAPPER_BLOCK_SIZE), prot); 741 742 memblock_reserve(dt_phys, size); 743 744 return dt_virt; 745 } 746