arch/arm64/mm/mmu.c

   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                                             prot | __pgprot(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 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), SECTION_SIZE);
 366         unsigned long kernel_x_end = round_up(__pa(__init_end), SECTION_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 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, SECTION_SIZE)) {
 455                 unsigned long aligned_start = round_down(__pa(_stext),
 456                                                         SECTION_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, SECTION_SIZE)) {
 464                 unsigned long aligned_end = round_up(__pa(__init_end),
 465                                                         SECTION_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_EXEC | PTE_RDONLY);
 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 | PTE_RDONLY;
 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 }