1 /* 2 * linux/mm/memory.c 3 * 4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 5 */ 6 7 /* 8 * demand-loading started 01.12.91 - seems it is high on the list of 9 * things wanted, and it should be easy to implement. - Linus 10 */ 11 12 /* 13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared 14 * pages started 02.12.91, seems to work. - Linus. 15 * 16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it 17 * would have taken more than the 6M I have free, but it worked well as 18 * far as I could see. 19 * 20 * Also corrected some "invalidate()"s - I wasn't doing enough of them. 21 */ 22 23 /* 24 * Real VM (paging to/from disk) started 18.12.91. Much more work and 25 * thought has to go into this. Oh, well.. 26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. 27 * Found it. Everything seems to work now. 28 * 20.12.91 - Ok, making the swap-device changeable like the root. 29 */ 30 31 /* 32 * 05.04.94 - Multi-page memory management added for v1.1. 33 * Idea by Alex Bligh (alex@cconcepts.co.uk) 34 * 35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG 36 * (Gerhard.Wichert@pdb.siemens.de) 37 * 38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) 39 */ 40 41 #include <linux/kernel_stat.h> 42 #include <linux/mm.h> 43 #include <linux/sched/mm.h> 44 #include <linux/sched/coredump.h> 45 #include <linux/sched/numa_balancing.h> 46 #include <linux/sched/task.h> 47 #include <linux/hugetlb.h> 48 #include <linux/mman.h> 49 #include <linux/swap.h> 50 #include <linux/highmem.h> 51 #include <linux/pagemap.h> 52 #include <linux/memremap.h> 53 #include <linux/ksm.h> 54 #include <linux/rmap.h> 55 #include <linux/export.h> 56 #include <linux/delayacct.h> 57 #include <linux/init.h> 58 #include <linux/pfn_t.h> 59 #include <linux/writeback.h> 60 #include <linux/memcontrol.h> 61 #include <linux/mmu_notifier.h> 62 #include <linux/kallsyms.h> 63 #include <linux/swapops.h> 64 #include <linux/elf.h> 65 #include <linux/gfp.h> 66 #include <linux/migrate.h> 67 #include <linux/string.h> 68 #include <linux/dma-debug.h> 69 #include <linux/debugfs.h> 70 #include <linux/userfaultfd_k.h> 71 #include <linux/dax.h> 72 #include <linux/oom.h> 73 74 #include <asm/io.h> 75 #include <asm/mmu_context.h> 76 #include <asm/pgalloc.h> 77 #include <linux/uaccess.h> 78 #include <asm/tlb.h> 79 #include <asm/tlbflush.h> 80 #include <asm/pgtable.h> 81 82 #include "internal.h" 83 84 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS 85 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. 86 #endif 87 88 #ifndef CONFIG_NEED_MULTIPLE_NODES 89 /* use the per-pgdat data instead for discontigmem - mbligh */ 90 unsigned long max_mapnr; 91 EXPORT_SYMBOL(max_mapnr); 92 93 struct page *mem_map; 94 EXPORT_SYMBOL(mem_map); 95 #endif 96 97 /* 98 * A number of key systems in x86 including ioremap() rely on the assumption 99 * that high_memory defines the upper bound on direct map memory, then end 100 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 101 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 102 * and ZONE_HIGHMEM. 103 */ 104 void *high_memory; 105 EXPORT_SYMBOL(high_memory); 106 107 /* 108 * Randomize the address space (stacks, mmaps, brk, etc.). 109 * 110 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 111 * as ancient (libc5 based) binaries can segfault. ) 112 */ 113 int randomize_va_space __read_mostly = 114 #ifdef CONFIG_COMPAT_BRK 115 1; 116 #else 117 2; 118 #endif 119 120 static int __init disable_randmaps(char *s) 121 { 122 randomize_va_space = 0; 123 return 1; 124 } 125 __setup("norandmaps", disable_randmaps); 126 127 unsigned long zero_pfn __read_mostly; 128 EXPORT_SYMBOL(zero_pfn); 129 130 unsigned long highest_memmap_pfn __read_mostly; 131 132 /* 133 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 134 */ 135 static int __init init_zero_pfn(void) 136 { 137 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 138 return 0; 139 } 140 core_initcall(init_zero_pfn); 141 142 143 #if defined(SPLIT_RSS_COUNTING) 144 145 void sync_mm_rss(struct mm_struct *mm) 146 { 147 int i; 148 149 for (i = 0; i < NR_MM_COUNTERS; i++) { 150 if (current->rss_stat.count[i]) { 151 add_mm_counter(mm, i, current->rss_stat.count[i]); 152 current->rss_stat.count[i] = 0; 153 } 154 } 155 current->rss_stat.events = 0; 156 } 157 158 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 159 { 160 struct task_struct *task = current; 161 162 if (likely(task->mm == mm)) 163 task->rss_stat.count[member] += val; 164 else 165 add_mm_counter(mm, member, val); 166 } 167 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 168 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 169 170 /* sync counter once per 64 page faults */ 171 #define TASK_RSS_EVENTS_THRESH (64) 172 static void check_sync_rss_stat(struct task_struct *task) 173 { 174 if (unlikely(task != current)) 175 return; 176 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 177 sync_mm_rss(task->mm); 178 } 179 #else /* SPLIT_RSS_COUNTING */ 180 181 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 182 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 183 184 static void check_sync_rss_stat(struct task_struct *task) 185 { 186 } 187 188 #endif /* SPLIT_RSS_COUNTING */ 189 190 #ifdef HAVE_GENERIC_MMU_GATHER 191 192 static bool tlb_next_batch(struct mmu_gather *tlb) 193 { 194 struct mmu_gather_batch *batch; 195 196 batch = tlb->active; 197 if (batch->next) { 198 tlb->active = batch->next; 199 return true; 200 } 201 202 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) 203 return false; 204 205 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 206 if (!batch) 207 return false; 208 209 tlb->batch_count++; 210 batch->next = NULL; 211 batch->nr = 0; 212 batch->max = MAX_GATHER_BATCH; 213 214 tlb->active->next = batch; 215 tlb->active = batch; 216 217 return true; 218 } 219 220 void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, 221 unsigned long start, unsigned long end) 222 { 223 tlb->mm = mm; 224 225 /* Is it from 0 to ~0? */ 226 tlb->fullmm = !(start | (end+1)); 227 tlb->need_flush_all = 0; 228 tlb->local.next = NULL; 229 tlb->local.nr = 0; 230 tlb->local.max = ARRAY_SIZE(tlb->__pages); 231 tlb->active = &tlb->local; 232 tlb->batch_count = 0; 233 234 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 235 tlb->batch = NULL; 236 #endif 237 tlb->page_size = 0; 238 239 __tlb_reset_range(tlb); 240 } 241 242 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) 243 { 244 if (!tlb->end) 245 return; 246 247 tlb_flush(tlb); 248 mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end); 249 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 250 tlb_table_flush(tlb); 251 #endif 252 __tlb_reset_range(tlb); 253 } 254 255 static void tlb_flush_mmu_free(struct mmu_gather *tlb) 256 { 257 struct mmu_gather_batch *batch; 258 259 for (batch = &tlb->local; batch && batch->nr; batch = batch->next) { 260 free_pages_and_swap_cache(batch->pages, batch->nr); 261 batch->nr = 0; 262 } 263 tlb->active = &tlb->local; 264 } 265 266 void tlb_flush_mmu(struct mmu_gather *tlb) 267 { 268 tlb_flush_mmu_tlbonly(tlb); 269 tlb_flush_mmu_free(tlb); 270 } 271 272 /* tlb_finish_mmu 273 * Called at the end of the shootdown operation to free up any resources 274 * that were required. 275 */ 276 void arch_tlb_finish_mmu(struct mmu_gather *tlb, 277 unsigned long start, unsigned long end, bool force) 278 { 279 struct mmu_gather_batch *batch, *next; 280 281 if (force) 282 __tlb_adjust_range(tlb, start, end - start); 283 284 tlb_flush_mmu(tlb); 285 286 /* keep the page table cache within bounds */ 287 check_pgt_cache(); 288 289 for (batch = tlb->local.next; batch; batch = next) { 290 next = batch->next; 291 free_pages((unsigned long)batch, 0); 292 } 293 tlb->local.next = NULL; 294 } 295 296 /* __tlb_remove_page 297 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 298 * handling the additional races in SMP caused by other CPUs caching valid 299 * mappings in their TLBs. Returns the number of free page slots left. 300 * When out of page slots we must call tlb_flush_mmu(). 301 *returns true if the caller should flush. 302 */ 303 bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size) 304 { 305 struct mmu_gather_batch *batch; 306 307 VM_BUG_ON(!tlb->end); 308 VM_WARN_ON(tlb->page_size != page_size); 309 310 batch = tlb->active; 311 /* 312 * Add the page and check if we are full. If so 313 * force a flush. 314 */ 315 batch->pages[batch->nr++] = page; 316 if (batch->nr == batch->max) { 317 if (!tlb_next_batch(tlb)) 318 return true; 319 batch = tlb->active; 320 } 321 VM_BUG_ON_PAGE(batch->nr > batch->max, page); 322 323 return false; 324 } 325 326 #endif /* HAVE_GENERIC_MMU_GATHER */ 327 328 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 329 330 /* 331 * See the comment near struct mmu_table_batch. 332 */ 333 334 static void tlb_remove_table_smp_sync(void *arg) 335 { 336 /* Simply deliver the interrupt */ 337 } 338 339 static void tlb_remove_table_one(void *table) 340 { 341 /* 342 * This isn't an RCU grace period and hence the page-tables cannot be 343 * assumed to be actually RCU-freed. 344 * 345 * It is however sufficient for software page-table walkers that rely on 346 * IRQ disabling. See the comment near struct mmu_table_batch. 347 */ 348 smp_call_function(tlb_remove_table_smp_sync, NULL, 1); 349 __tlb_remove_table(table); 350 } 351 352 static void tlb_remove_table_rcu(struct rcu_head *head) 353 { 354 struct mmu_table_batch *batch; 355 int i; 356 357 batch = container_of(head, struct mmu_table_batch, rcu); 358 359 for (i = 0; i < batch->nr; i++) 360 __tlb_remove_table(batch->tables[i]); 361 362 free_page((unsigned long)batch); 363 } 364 365 void tlb_table_flush(struct mmu_gather *tlb) 366 { 367 struct mmu_table_batch **batch = &tlb->batch; 368 369 if (*batch) { 370 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); 371 *batch = NULL; 372 } 373 } 374 375 void tlb_remove_table(struct mmu_gather *tlb, void *table) 376 { 377 struct mmu_table_batch **batch = &tlb->batch; 378 379 /* 380 * When there's less then two users of this mm there cannot be a 381 * concurrent page-table walk. 382 */ 383 if (atomic_read(&tlb->mm->mm_users) < 2) { 384 __tlb_remove_table(table); 385 return; 386 } 387 388 if (*batch == NULL) { 389 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); 390 if (*batch == NULL) { 391 tlb_remove_table_one(table); 392 return; 393 } 394 (*batch)->nr = 0; 395 } 396 (*batch)->tables[(*batch)->nr++] = table; 397 if ((*batch)->nr == MAX_TABLE_BATCH) 398 tlb_table_flush(tlb); 399 } 400 401 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ 402 403 /* tlb_gather_mmu 404 * Called to initialize an (on-stack) mmu_gather structure for page-table 405 * tear-down from @mm. The @fullmm argument is used when @mm is without 406 * users and we're going to destroy the full address space (exit/execve). 407 */ 408 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, 409 unsigned long start, unsigned long end) 410 { 411 arch_tlb_gather_mmu(tlb, mm, start, end); 412 inc_tlb_flush_pending(tlb->mm); 413 } 414 415 void tlb_finish_mmu(struct mmu_gather *tlb, 416 unsigned long start, unsigned long end) 417 { 418 /* 419 * If there are parallel threads are doing PTE changes on same range 420 * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB 421 * flush by batching, a thread has stable TLB entry can fail to flush 422 * the TLB by observing pte_none|!pte_dirty, for example so flush TLB 423 * forcefully if we detect parallel PTE batching threads. 424 */ 425 bool force = mm_tlb_flush_nested(tlb->mm); 426 427 arch_tlb_finish_mmu(tlb, start, end, force); 428 dec_tlb_flush_pending(tlb->mm); 429 } 430 431 /* 432 * Note: this doesn't free the actual pages themselves. That 433 * has been handled earlier when unmapping all the memory regions. 434 */ 435 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 436 unsigned long addr) 437 { 438 pgtable_t token = pmd_pgtable(*pmd); 439 pmd_clear(pmd); 440 pte_free_tlb(tlb, token, addr); 441 mm_dec_nr_ptes(tlb->mm); 442 } 443 444 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 445 unsigned long addr, unsigned long end, 446 unsigned long floor, unsigned long ceiling) 447 { 448 pmd_t *pmd; 449 unsigned long next; 450 unsigned long start; 451 452 start = addr; 453 pmd = pmd_offset(pud, addr); 454 do { 455 next = pmd_addr_end(addr, end); 456 if (pmd_none_or_clear_bad(pmd)) 457 continue; 458 free_pte_range(tlb, pmd, addr); 459 } while (pmd++, addr = next, addr != end); 460 461 start &= PUD_MASK; 462 if (start < floor) 463 return; 464 if (ceiling) { 465 ceiling &= PUD_MASK; 466 if (!ceiling) 467 return; 468 } 469 if (end - 1 > ceiling - 1) 470 return; 471 472 pmd = pmd_offset(pud, start); 473 pud_clear(pud); 474 pmd_free_tlb(tlb, pmd, start); 475 mm_dec_nr_pmds(tlb->mm); 476 } 477 478 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d, 479 unsigned long addr, unsigned long end, 480 unsigned long floor, unsigned long ceiling) 481 { 482 pud_t *pud; 483 unsigned long next; 484 unsigned long start; 485 486 start = addr; 487 pud = pud_offset(p4d, addr); 488 do { 489 next = pud_addr_end(addr, end); 490 if (pud_none_or_clear_bad(pud)) 491 continue; 492 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 493 } while (pud++, addr = next, addr != end); 494 495 start &= P4D_MASK; 496 if (start < floor) 497 return; 498 if (ceiling) { 499 ceiling &= P4D_MASK; 500 if (!ceiling) 501 return; 502 } 503 if (end - 1 > ceiling - 1) 504 return; 505 506 pud = pud_offset(p4d, start); 507 p4d_clear(p4d); 508 pud_free_tlb(tlb, pud, start); 509 mm_dec_nr_puds(tlb->mm); 510 } 511 512 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd, 513 unsigned long addr, unsigned long end, 514 unsigned long floor, unsigned long ceiling) 515 { 516 p4d_t *p4d; 517 unsigned long next; 518 unsigned long start; 519 520 start = addr; 521 p4d = p4d_offset(pgd, addr); 522 do { 523 next = p4d_addr_end(addr, end); 524 if (p4d_none_or_clear_bad(p4d)) 525 continue; 526 free_pud_range(tlb, p4d, addr, next, floor, ceiling); 527 } while (p4d++, addr = next, addr != end); 528 529 start &= PGDIR_MASK; 530 if (start < floor) 531 return; 532 if (ceiling) { 533 ceiling &= PGDIR_MASK; 534 if (!ceiling) 535 return; 536 } 537 if (end - 1 > ceiling - 1) 538 return; 539 540 p4d = p4d_offset(pgd, start); 541 pgd_clear(pgd); 542 p4d_free_tlb(tlb, p4d, start); 543 } 544 545 /* 546 * This function frees user-level page tables of a process. 547 */ 548 void free_pgd_range(struct mmu_gather *tlb, 549 unsigned long addr, unsigned long end, 550 unsigned long floor, unsigned long ceiling) 551 { 552 pgd_t *pgd; 553 unsigned long next; 554 555 /* 556 * The next few lines have given us lots of grief... 557 * 558 * Why are we testing PMD* at this top level? Because often 559 * there will be no work to do at all, and we'd prefer not to 560 * go all the way down to the bottom just to discover that. 561 * 562 * Why all these "- 1"s? Because 0 represents both the bottom 563 * of the address space and the top of it (using -1 for the 564 * top wouldn't help much: the masks would do the wrong thing). 565 * The rule is that addr 0 and floor 0 refer to the bottom of 566 * the address space, but end 0 and ceiling 0 refer to the top 567 * Comparisons need to use "end - 1" and "ceiling - 1" (though 568 * that end 0 case should be mythical). 569 * 570 * Wherever addr is brought up or ceiling brought down, we must 571 * be careful to reject "the opposite 0" before it confuses the 572 * subsequent tests. But what about where end is brought down 573 * by PMD_SIZE below? no, end can't go down to 0 there. 574 * 575 * Whereas we round start (addr) and ceiling down, by different 576 * masks at different levels, in order to test whether a table 577 * now has no other vmas using it, so can be freed, we don't 578 * bother to round floor or end up - the tests don't need that. 579 */ 580 581 addr &= PMD_MASK; 582 if (addr < floor) { 583 addr += PMD_SIZE; 584 if (!addr) 585 return; 586 } 587 if (ceiling) { 588 ceiling &= PMD_MASK; 589 if (!ceiling) 590 return; 591 } 592 if (end - 1 > ceiling - 1) 593 end -= PMD_SIZE; 594 if (addr > end - 1) 595 return; 596 /* 597 * We add page table cache pages with PAGE_SIZE, 598 * (see pte_free_tlb()), flush the tlb if we need 599 */ 600 tlb_remove_check_page_size_change(tlb, PAGE_SIZE); 601 pgd = pgd_offset(tlb->mm, addr); 602 do { 603 next = pgd_addr_end(addr, end); 604 if (pgd_none_or_clear_bad(pgd)) 605 continue; 606 free_p4d_range(tlb, pgd, addr, next, floor, ceiling); 607 } while (pgd++, addr = next, addr != end); 608 } 609 610 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 611 unsigned long floor, unsigned long ceiling) 612 { 613 while (vma) { 614 struct vm_area_struct *next = vma->vm_next; 615 unsigned long addr = vma->vm_start; 616 617 /* 618 * Hide vma from rmap and truncate_pagecache before freeing 619 * pgtables 620 */ 621 unlink_anon_vmas(vma); 622 unlink_file_vma(vma); 623 624 if (is_vm_hugetlb_page(vma)) { 625 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 626 floor, next ? next->vm_start : ceiling); 627 } else { 628 /* 629 * Optimization: gather nearby vmas into one call down 630 */ 631 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 632 && !is_vm_hugetlb_page(next)) { 633 vma = next; 634 next = vma->vm_next; 635 unlink_anon_vmas(vma); 636 unlink_file_vma(vma); 637 } 638 free_pgd_range(tlb, addr, vma->vm_end, 639 floor, next ? next->vm_start : ceiling); 640 } 641 vma = next; 642 } 643 } 644 645 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 646 { 647 spinlock_t *ptl; 648 pgtable_t new = pte_alloc_one(mm, address); 649 if (!new) 650 return -ENOMEM; 651 652 /* 653 * Ensure all pte setup (eg. pte page lock and page clearing) are 654 * visible before the pte is made visible to other CPUs by being 655 * put into page tables. 656 * 657 * The other side of the story is the pointer chasing in the page 658 * table walking code (when walking the page table without locking; 659 * ie. most of the time). Fortunately, these data accesses consist 660 * of a chain of data-dependent loads, meaning most CPUs (alpha 661 * being the notable exception) will already guarantee loads are 662 * seen in-order. See the alpha page table accessors for the 663 * smp_read_barrier_depends() barriers in page table walking code. 664 */ 665 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 666 667 ptl = pmd_lock(mm, pmd); 668 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 669 mm_inc_nr_ptes(mm); 670 pmd_populate(mm, pmd, new); 671 new = NULL; 672 } 673 spin_unlock(ptl); 674 if (new) 675 pte_free(mm, new); 676 return 0; 677 } 678 679 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 680 { 681 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 682 if (!new) 683 return -ENOMEM; 684 685 smp_wmb(); /* See comment in __pte_alloc */ 686 687 spin_lock(&init_mm.page_table_lock); 688 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 689 pmd_populate_kernel(&init_mm, pmd, new); 690 new = NULL; 691 } 692 spin_unlock(&init_mm.page_table_lock); 693 if (new) 694 pte_free_kernel(&init_mm, new); 695 return 0; 696 } 697 698 static inline void init_rss_vec(int *rss) 699 { 700 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 701 } 702 703 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 704 { 705 int i; 706 707 if (current->mm == mm) 708 sync_mm_rss(mm); 709 for (i = 0; i < NR_MM_COUNTERS; i++) 710 if (rss[i]) 711 add_mm_counter(mm, i, rss[i]); 712 } 713 714 /* 715 * This function is called to print an error when a bad pte 716 * is found. For example, we might have a PFN-mapped pte in 717 * a region that doesn't allow it. 718 * 719 * The calling function must still handle the error. 720 */ 721 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 722 pte_t pte, struct page *page) 723 { 724 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 725 p4d_t *p4d = p4d_offset(pgd, addr); 726 pud_t *pud = pud_offset(p4d, addr); 727 pmd_t *pmd = pmd_offset(pud, addr); 728 struct address_space *mapping; 729 pgoff_t index; 730 static unsigned long resume; 731 static unsigned long nr_shown; 732 static unsigned long nr_unshown; 733 734 /* 735 * Allow a burst of 60 reports, then keep quiet for that minute; 736 * or allow a steady drip of one report per second. 737 */ 738 if (nr_shown == 60) { 739 if (time_before(jiffies, resume)) { 740 nr_unshown++; 741 return; 742 } 743 if (nr_unshown) { 744 pr_alert("BUG: Bad page map: %lu messages suppressed\n", 745 nr_unshown); 746 nr_unshown = 0; 747 } 748 nr_shown = 0; 749 } 750 if (nr_shown++ == 0) 751 resume = jiffies + 60 * HZ; 752 753 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 754 index = linear_page_index(vma, addr); 755 756 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 757 current->comm, 758 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 759 if (page) 760 dump_page(page, "bad pte"); 761 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 762 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 763 /* 764 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 765 */ 766 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n", 767 vma->vm_file, 768 vma->vm_ops ? vma->vm_ops->fault : NULL, 769 vma->vm_file ? vma->vm_file->f_op->mmap : NULL, 770 mapping ? mapping->a_ops->readpage : NULL); 771 dump_stack(); 772 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); 773 } 774 775 /* 776 * vm_normal_page -- This function gets the "struct page" associated with a pte. 777 * 778 * "Special" mappings do not wish to be associated with a "struct page" (either 779 * it doesn't exist, or it exists but they don't want to touch it). In this 780 * case, NULL is returned here. "Normal" mappings do have a struct page. 781 * 782 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 783 * pte bit, in which case this function is trivial. Secondly, an architecture 784 * may not have a spare pte bit, which requires a more complicated scheme, 785 * described below. 786 * 787 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 788 * special mapping (even if there are underlying and valid "struct pages"). 789 * COWed pages of a VM_PFNMAP are always normal. 790 * 791 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 792 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 793 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 794 * mapping will always honor the rule 795 * 796 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 797 * 798 * And for normal mappings this is false. 799 * 800 * This restricts such mappings to be a linear translation from virtual address 801 * to pfn. To get around this restriction, we allow arbitrary mappings so long 802 * as the vma is not a COW mapping; in that case, we know that all ptes are 803 * special (because none can have been COWed). 804 * 805 * 806 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 807 * 808 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 809 * page" backing, however the difference is that _all_ pages with a struct 810 * page (that is, those where pfn_valid is true) are refcounted and considered 811 * normal pages by the VM. The disadvantage is that pages are refcounted 812 * (which can be slower and simply not an option for some PFNMAP users). The 813 * advantage is that we don't have to follow the strict linearity rule of 814 * PFNMAP mappings in order to support COWable mappings. 815 * 816 */ 817 #ifdef __HAVE_ARCH_PTE_SPECIAL 818 # define HAVE_PTE_SPECIAL 1 819 #else 820 # define HAVE_PTE_SPECIAL 0 821 #endif 822 struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 823 pte_t pte, bool with_public_device) 824 { 825 unsigned long pfn = pte_pfn(pte); 826 827 if (HAVE_PTE_SPECIAL) { 828 if (likely(!pte_special(pte))) 829 goto check_pfn; 830 if (vma->vm_ops && vma->vm_ops->find_special_page) 831 return vma->vm_ops->find_special_page(vma, addr); 832 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 833 return NULL; 834 if (is_zero_pfn(pfn)) 835 return NULL; 836 837 /* 838 * Device public pages are special pages (they are ZONE_DEVICE 839 * pages but different from persistent memory). They behave 840 * allmost like normal pages. The difference is that they are 841 * not on the lru and thus should never be involve with any- 842 * thing that involve lru manipulation (mlock, numa balancing, 843 * ...). 844 * 845 * This is why we still want to return NULL for such page from 846 * vm_normal_page() so that we do not have to special case all 847 * call site of vm_normal_page(). 848 */ 849 if (likely(pfn <= highest_memmap_pfn)) { 850 struct page *page = pfn_to_page(pfn); 851 852 if (is_device_public_page(page)) { 853 if (with_public_device) 854 return page; 855 return NULL; 856 } 857 } 858 print_bad_pte(vma, addr, pte, NULL); 859 return NULL; 860 } 861 862 /* !HAVE_PTE_SPECIAL case follows: */ 863 864 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 865 if (vma->vm_flags & VM_MIXEDMAP) { 866 if (!pfn_valid(pfn)) 867 return NULL; 868 goto out; 869 } else { 870 unsigned long off; 871 off = (addr - vma->vm_start) >> PAGE_SHIFT; 872 if (pfn == vma->vm_pgoff + off) 873 return NULL; 874 if (!is_cow_mapping(vma->vm_flags)) 875 return NULL; 876 } 877 } 878 879 if (is_zero_pfn(pfn)) 880 return NULL; 881 check_pfn: 882 if (unlikely(pfn > highest_memmap_pfn)) { 883 print_bad_pte(vma, addr, pte, NULL); 884 return NULL; 885 } 886 887 /* 888 * NOTE! We still have PageReserved() pages in the page tables. 889 * eg. VDSO mappings can cause them to exist. 890 */ 891 out: 892 return pfn_to_page(pfn); 893 } 894 895 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 896 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr, 897 pmd_t pmd) 898 { 899 unsigned long pfn = pmd_pfn(pmd); 900 901 /* 902 * There is no pmd_special() but there may be special pmds, e.g. 903 * in a direct-access (dax) mapping, so let's just replicate the 904 * !HAVE_PTE_SPECIAL case from vm_normal_page() here. 905 */ 906 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 907 if (vma->vm_flags & VM_MIXEDMAP) { 908 if (!pfn_valid(pfn)) 909 return NULL; 910 goto out; 911 } else { 912 unsigned long off; 913 off = (addr - vma->vm_start) >> PAGE_SHIFT; 914 if (pfn == vma->vm_pgoff + off) 915 return NULL; 916 if (!is_cow_mapping(vma->vm_flags)) 917 return NULL; 918 } 919 } 920 921 if (is_zero_pfn(pfn)) 922 return NULL; 923 if (unlikely(pfn > highest_memmap_pfn)) 924 return NULL; 925 926 /* 927 * NOTE! We still have PageReserved() pages in the page tables. 928 * eg. VDSO mappings can cause them to exist. 929 */ 930 out: 931 return pfn_to_page(pfn); 932 } 933 #endif 934 935 /* 936 * copy one vm_area from one task to the other. Assumes the page tables 937 * already present in the new task to be cleared in the whole range 938 * covered by this vma. 939 */ 940 941 static inline unsigned long 942 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 943 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 944 unsigned long addr, int *rss) 945 { 946 unsigned long vm_flags = vma->vm_flags; 947 pte_t pte = *src_pte; 948 struct page *page; 949 950 /* pte contains position in swap or file, so copy. */ 951 if (unlikely(!pte_present(pte))) { 952 swp_entry_t entry = pte_to_swp_entry(pte); 953 954 if (likely(!non_swap_entry(entry))) { 955 if (swap_duplicate(entry) < 0) 956 return entry.val; 957 958 /* make sure dst_mm is on swapoff's mmlist. */ 959 if (unlikely(list_empty(&dst_mm->mmlist))) { 960 spin_lock(&mmlist_lock); 961 if (list_empty(&dst_mm->mmlist)) 962 list_add(&dst_mm->mmlist, 963 &src_mm->mmlist); 964 spin_unlock(&mmlist_lock); 965 } 966 rss[MM_SWAPENTS]++; 967 } else if (is_migration_entry(entry)) { 968 page = migration_entry_to_page(entry); 969 970 rss[mm_counter(page)]++; 971 972 if (is_write_migration_entry(entry) && 973 is_cow_mapping(vm_flags)) { 974 /* 975 * COW mappings require pages in both 976 * parent and child to be set to read. 977 */ 978 make_migration_entry_read(&entry); 979 pte = swp_entry_to_pte(entry); 980 if (pte_swp_soft_dirty(*src_pte)) 981 pte = pte_swp_mksoft_dirty(pte); 982 set_pte_at(src_mm, addr, src_pte, pte); 983 } 984 } else if (is_device_private_entry(entry)) { 985 page = device_private_entry_to_page(entry); 986 987 /* 988 * Update rss count even for unaddressable pages, as 989 * they should treated just like normal pages in this 990 * respect. 991 * 992 * We will likely want to have some new rss counters 993 * for unaddressable pages, at some point. But for now 994 * keep things as they are. 995 */ 996 get_page(page); 997 rss[mm_counter(page)]++; 998 page_dup_rmap(page, false); 999 1000 /* 1001 * We do not preserve soft-dirty information, because so 1002 * far, checkpoint/restore is the only feature that 1003 * requires that. And checkpoint/restore does not work 1004 * when a device driver is involved (you cannot easily 1005 * save and restore device driver state). 1006 */ 1007 if (is_write_device_private_entry(entry) && 1008 is_cow_mapping(vm_flags)) { 1009 make_device_private_entry_read(&entry); 1010 pte = swp_entry_to_pte(entry); 1011 set_pte_at(src_mm, addr, src_pte, pte); 1012 } 1013 } 1014 goto out_set_pte; 1015 } 1016 1017 /* 1018 * If it's a COW mapping, write protect it both 1019 * in the parent and the child 1020 */ 1021 if (is_cow_mapping(vm_flags)) { 1022 ptep_set_wrprotect(src_mm, addr, src_pte); 1023 pte = pte_wrprotect(pte); 1024 } 1025 1026 /* 1027 * If it's a shared mapping, mark it clean in 1028 * the child 1029 */ 1030 if (vm_flags & VM_SHARED) 1031 pte = pte_mkclean(pte); 1032 pte = pte_mkold(pte); 1033 1034 page = vm_normal_page(vma, addr, pte); 1035 if (page) { 1036 get_page(page); 1037 page_dup_rmap(page, false); 1038 rss[mm_counter(page)]++; 1039 } else if (pte_devmap(pte)) { 1040 page = pte_page(pte); 1041 1042 /* 1043 * Cache coherent device memory behave like regular page and 1044 * not like persistent memory page. For more informations see 1045 * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h 1046 */ 1047 if (is_device_public_page(page)) { 1048 get_page(page); 1049 page_dup_rmap(page, false); 1050 rss[mm_counter(page)]++; 1051 } 1052 } 1053 1054 out_set_pte: 1055 set_pte_at(dst_mm, addr, dst_pte, pte); 1056 return 0; 1057 } 1058 1059 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1060 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 1061 unsigned long addr, unsigned long end) 1062 { 1063 pte_t *orig_src_pte, *orig_dst_pte; 1064 pte_t *src_pte, *dst_pte; 1065 spinlock_t *src_ptl, *dst_ptl; 1066 int progress = 0; 1067 int rss[NR_MM_COUNTERS]; 1068 swp_entry_t entry = (swp_entry_t){0}; 1069 1070 again: 1071 init_rss_vec(rss); 1072 1073 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 1074 if (!dst_pte) 1075 return -ENOMEM; 1076 src_pte = pte_offset_map(src_pmd, addr); 1077 src_ptl = pte_lockptr(src_mm, src_pmd); 1078 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 1079 orig_src_pte = src_pte; 1080 orig_dst_pte = dst_pte; 1081 arch_enter_lazy_mmu_mode(); 1082 1083 do { 1084 /* 1085 * We are holding two locks at this point - either of them 1086 * could generate latencies in another task on another CPU. 1087 */ 1088 if (progress >= 32) { 1089 progress = 0; 1090 if (need_resched() || 1091 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 1092 break; 1093 } 1094 if (pte_none(*src_pte)) { 1095 progress++; 1096 continue; 1097 } 1098 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 1099 vma, addr, rss); 1100 if (entry.val) 1101 break; 1102 progress += 8; 1103 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 1104 1105 arch_leave_lazy_mmu_mode(); 1106 spin_unlock(src_ptl); 1107 pte_unmap(orig_src_pte); 1108 add_mm_rss_vec(dst_mm, rss); 1109 pte_unmap_unlock(orig_dst_pte, dst_ptl); 1110 cond_resched(); 1111 1112 if (entry.val) { 1113 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 1114 return -ENOMEM; 1115 progress = 0; 1116 } 1117 if (addr != end) 1118 goto again; 1119 return 0; 1120 } 1121 1122 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1123 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 1124 unsigned long addr, unsigned long end) 1125 { 1126 pmd_t *src_pmd, *dst_pmd; 1127 unsigned long next; 1128 1129 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 1130 if (!dst_pmd) 1131 return -ENOMEM; 1132 src_pmd = pmd_offset(src_pud, addr); 1133 do { 1134 next = pmd_addr_end(addr, end); 1135 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd) 1136 || pmd_devmap(*src_pmd)) { 1137 int err; 1138 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma); 1139 err = copy_huge_pmd(dst_mm, src_mm, 1140 dst_pmd, src_pmd, addr, vma); 1141 if (err == -ENOMEM) 1142 return -ENOMEM; 1143 if (!err) 1144 continue; 1145 /* fall through */ 1146 } 1147 if (pmd_none_or_clear_bad(src_pmd)) 1148 continue; 1149 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 1150 vma, addr, next)) 1151 return -ENOMEM; 1152 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 1153 return 0; 1154 } 1155 1156 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1157 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma, 1158 unsigned long addr, unsigned long end) 1159 { 1160 pud_t *src_pud, *dst_pud; 1161 unsigned long next; 1162 1163 dst_pud = pud_alloc(dst_mm, dst_p4d, addr); 1164 if (!dst_pud) 1165 return -ENOMEM; 1166 src_pud = pud_offset(src_p4d, addr); 1167 do { 1168 next = pud_addr_end(addr, end); 1169 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) { 1170 int err; 1171 1172 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma); 1173 err = copy_huge_pud(dst_mm, src_mm, 1174 dst_pud, src_pud, addr, vma); 1175 if (err == -ENOMEM) 1176 return -ENOMEM; 1177 if (!err) 1178 continue; 1179 /* fall through */ 1180 } 1181 if (pud_none_or_clear_bad(src_pud)) 1182 continue; 1183 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 1184 vma, addr, next)) 1185 return -ENOMEM; 1186 } while (dst_pud++, src_pud++, addr = next, addr != end); 1187 return 0; 1188 } 1189 1190 static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1191 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 1192 unsigned long addr, unsigned long end) 1193 { 1194 p4d_t *src_p4d, *dst_p4d; 1195 unsigned long next; 1196 1197 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr); 1198 if (!dst_p4d) 1199 return -ENOMEM; 1200 src_p4d = p4d_offset(src_pgd, addr); 1201 do { 1202 next = p4d_addr_end(addr, end); 1203 if (p4d_none_or_clear_bad(src_p4d)) 1204 continue; 1205 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d, 1206 vma, addr, next)) 1207 return -ENOMEM; 1208 } while (dst_p4d++, src_p4d++, addr = next, addr != end); 1209 return 0; 1210 } 1211 1212 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1213 struct vm_area_struct *vma) 1214 { 1215 pgd_t *src_pgd, *dst_pgd; 1216 unsigned long next; 1217 unsigned long addr = vma->vm_start; 1218 unsigned long end = vma->vm_end; 1219 unsigned long mmun_start; /* For mmu_notifiers */ 1220 unsigned long mmun_end; /* For mmu_notifiers */ 1221 bool is_cow; 1222 int ret; 1223 1224 /* 1225 * Don't copy ptes where a page fault will fill them correctly. 1226 * Fork becomes much lighter when there are big shared or private 1227 * readonly mappings. The tradeoff is that copy_page_range is more 1228 * efficient than faulting. 1229 */ 1230 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) && 1231 !vma->anon_vma) 1232 return 0; 1233 1234 if (is_vm_hugetlb_page(vma)) 1235 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 1236 1237 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 1238 /* 1239 * We do not free on error cases below as remove_vma 1240 * gets called on error from higher level routine 1241 */ 1242 ret = track_pfn_copy(vma); 1243 if (ret) 1244 return ret; 1245 } 1246 1247 /* 1248 * We need to invalidate the secondary MMU mappings only when 1249 * there could be a permission downgrade on the ptes of the 1250 * parent mm. And a permission downgrade will only happen if 1251 * is_cow_mapping() returns true. 1252 */ 1253 is_cow = is_cow_mapping(vma->vm_flags); 1254 mmun_start = addr; 1255 mmun_end = end; 1256 if (is_cow) 1257 mmu_notifier_invalidate_range_start(src_mm, mmun_start, 1258 mmun_end); 1259 1260 ret = 0; 1261 dst_pgd = pgd_offset(dst_mm, addr); 1262 src_pgd = pgd_offset(src_mm, addr); 1263 do { 1264 next = pgd_addr_end(addr, end); 1265 if (pgd_none_or_clear_bad(src_pgd)) 1266 continue; 1267 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd, 1268 vma, addr, next))) { 1269 ret = -ENOMEM; 1270 break; 1271 } 1272 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1273 1274 if (is_cow) 1275 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); 1276 return ret; 1277 } 1278 1279 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1280 struct vm_area_struct *vma, pmd_t *pmd, 1281 unsigned long addr, unsigned long end, 1282 struct zap_details *details) 1283 { 1284 struct mm_struct *mm = tlb->mm; 1285 int force_flush = 0; 1286 int rss[NR_MM_COUNTERS]; 1287 spinlock_t *ptl; 1288 pte_t *start_pte; 1289 pte_t *pte; 1290 swp_entry_t entry; 1291 1292 tlb_remove_check_page_size_change(tlb, PAGE_SIZE); 1293 again: 1294 init_rss_vec(rss); 1295 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1296 pte = start_pte; 1297 flush_tlb_batched_pending(mm); 1298 arch_enter_lazy_mmu_mode(); 1299 do { 1300 pte_t ptent = *pte; 1301 if (pte_none(ptent)) 1302 continue; 1303 1304 if (pte_present(ptent)) { 1305 struct page *page; 1306 1307 page = _vm_normal_page(vma, addr, ptent, true); 1308 if (unlikely(details) && page) { 1309 /* 1310 * unmap_shared_mapping_pages() wants to 1311 * invalidate cache without truncating: 1312 * unmap shared but keep private pages. 1313 */ 1314 if (details->check_mapping && 1315 details->check_mapping != page_rmapping(page)) 1316 continue; 1317 } 1318 ptent = ptep_get_and_clear_full(mm, addr, pte, 1319 tlb->fullmm); 1320 tlb_remove_tlb_entry(tlb, pte, addr); 1321 if (unlikely(!page)) 1322 continue; 1323 1324 if (!PageAnon(page)) { 1325 if (pte_dirty(ptent)) { 1326 force_flush = 1; 1327 set_page_dirty(page); 1328 } 1329 if (pte_young(ptent) && 1330 likely(!(vma->vm_flags & VM_SEQ_READ))) 1331 mark_page_accessed(page); 1332 } 1333 rss[mm_counter(page)]--; 1334 page_remove_rmap(page, false); 1335 if (unlikely(page_mapcount(page) < 0)) 1336 print_bad_pte(vma, addr, ptent, page); 1337 if (unlikely(__tlb_remove_page(tlb, page))) { 1338 force_flush = 1; 1339 addr += PAGE_SIZE; 1340 break; 1341 } 1342 continue; 1343 } 1344 1345 entry = pte_to_swp_entry(ptent); 1346 if (non_swap_entry(entry) && is_device_private_entry(entry)) { 1347 struct page *page = device_private_entry_to_page(entry); 1348 1349 if (unlikely(details && details->check_mapping)) { 1350 /* 1351 * unmap_shared_mapping_pages() wants to 1352 * invalidate cache without truncating: 1353 * unmap shared but keep private pages. 1354 */ 1355 if (details->check_mapping != 1356 page_rmapping(page)) 1357 continue; 1358 } 1359 1360 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1361 rss[mm_counter(page)]--; 1362 page_remove_rmap(page, false); 1363 put_page(page); 1364 continue; 1365 } 1366 1367 /* If details->check_mapping, we leave swap entries. */ 1368 if (unlikely(details)) 1369 continue; 1370 1371 entry = pte_to_swp_entry(ptent); 1372 if (!non_swap_entry(entry)) 1373 rss[MM_SWAPENTS]--; 1374 else if (is_migration_entry(entry)) { 1375 struct page *page; 1376 1377 page = migration_entry_to_page(entry); 1378 rss[mm_counter(page)]--; 1379 } 1380 if (unlikely(!free_swap_and_cache(entry))) 1381 print_bad_pte(vma, addr, ptent, NULL); 1382 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1383 } while (pte++, addr += PAGE_SIZE, addr != end); 1384 1385 add_mm_rss_vec(mm, rss); 1386 arch_leave_lazy_mmu_mode(); 1387 1388 /* Do the actual TLB flush before dropping ptl */ 1389 if (force_flush) 1390 tlb_flush_mmu_tlbonly(tlb); 1391 pte_unmap_unlock(start_pte, ptl); 1392 1393 /* 1394 * If we forced a TLB flush (either due to running out of 1395 * batch buffers or because we needed to flush dirty TLB 1396 * entries before releasing the ptl), free the batched 1397 * memory too. Restart if we didn't do everything. 1398 */ 1399 if (force_flush) { 1400 force_flush = 0; 1401 tlb_flush_mmu_free(tlb); 1402 if (addr != end) 1403 goto again; 1404 } 1405 1406 return addr; 1407 } 1408 1409 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1410 struct vm_area_struct *vma, pud_t *pud, 1411 unsigned long addr, unsigned long end, 1412 struct zap_details *details) 1413 { 1414 pmd_t *pmd; 1415 unsigned long next; 1416 1417 pmd = pmd_offset(pud, addr); 1418 do { 1419 next = pmd_addr_end(addr, end); 1420 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) { 1421 if (next - addr != HPAGE_PMD_SIZE) { 1422 VM_BUG_ON_VMA(vma_is_anonymous(vma) && 1423 !rwsem_is_locked(&tlb->mm->mmap_sem), vma); 1424 __split_huge_pmd(vma, pmd, addr, false, NULL); 1425 } else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1426 goto next; 1427 /* fall through */ 1428 } 1429 /* 1430 * Here there can be other concurrent MADV_DONTNEED or 1431 * trans huge page faults running, and if the pmd is 1432 * none or trans huge it can change under us. This is 1433 * because MADV_DONTNEED holds the mmap_sem in read 1434 * mode. 1435 */ 1436 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1437 goto next; 1438 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1439 next: 1440 cond_resched(); 1441 } while (pmd++, addr = next, addr != end); 1442 1443 return addr; 1444 } 1445 1446 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1447 struct vm_area_struct *vma, p4d_t *p4d, 1448 unsigned long addr, unsigned long end, 1449 struct zap_details *details) 1450 { 1451 pud_t *pud; 1452 unsigned long next; 1453 1454 pud = pud_offset(p4d, addr); 1455 do { 1456 next = pud_addr_end(addr, end); 1457 if (pud_trans_huge(*pud) || pud_devmap(*pud)) { 1458 if (next - addr != HPAGE_PUD_SIZE) { 1459 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma); 1460 split_huge_pud(vma, pud, addr); 1461 } else if (zap_huge_pud(tlb, vma, pud, addr)) 1462 goto next; 1463 /* fall through */ 1464 } 1465 if (pud_none_or_clear_bad(pud)) 1466 continue; 1467 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1468 next: 1469 cond_resched(); 1470 } while (pud++, addr = next, addr != end); 1471 1472 return addr; 1473 } 1474 1475 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb, 1476 struct vm_area_struct *vma, pgd_t *pgd, 1477 unsigned long addr, unsigned long end, 1478 struct zap_details *details) 1479 { 1480 p4d_t *p4d; 1481 unsigned long next; 1482 1483 p4d = p4d_offset(pgd, addr); 1484 do { 1485 next = p4d_addr_end(addr, end); 1486 if (p4d_none_or_clear_bad(p4d)) 1487 continue; 1488 next = zap_pud_range(tlb, vma, p4d, addr, next, details); 1489 } while (p4d++, addr = next, addr != end); 1490 1491 return addr; 1492 } 1493 1494 void unmap_page_range(struct mmu_gather *tlb, 1495 struct vm_area_struct *vma, 1496 unsigned long addr, unsigned long end, 1497 struct zap_details *details) 1498 { 1499 pgd_t *pgd; 1500 unsigned long next; 1501 1502 BUG_ON(addr >= end); 1503 tlb_start_vma(tlb, vma); 1504 pgd = pgd_offset(vma->vm_mm, addr); 1505 do { 1506 next = pgd_addr_end(addr, end); 1507 if (pgd_none_or_clear_bad(pgd)) 1508 continue; 1509 next = zap_p4d_range(tlb, vma, pgd, addr, next, details); 1510 } while (pgd++, addr = next, addr != end); 1511 tlb_end_vma(tlb, vma); 1512 } 1513 1514 1515 static void unmap_single_vma(struct mmu_gather *tlb, 1516 struct vm_area_struct *vma, unsigned long start_addr, 1517 unsigned long end_addr, 1518 struct zap_details *details) 1519 { 1520 unsigned long start = max(vma->vm_start, start_addr); 1521 unsigned long end; 1522 1523 if (start >= vma->vm_end) 1524 return; 1525 end = min(vma->vm_end, end_addr); 1526 if (end <= vma->vm_start) 1527 return; 1528 1529 if (vma->vm_file) 1530 uprobe_munmap(vma, start, end); 1531 1532 if (unlikely(vma->vm_flags & VM_PFNMAP)) 1533 untrack_pfn(vma, 0, 0); 1534 1535 if (start != end) { 1536 if (unlikely(is_vm_hugetlb_page(vma))) { 1537 /* 1538 * It is undesirable to test vma->vm_file as it 1539 * should be non-null for valid hugetlb area. 1540 * However, vm_file will be NULL in the error 1541 * cleanup path of mmap_region. When 1542 * hugetlbfs ->mmap method fails, 1543 * mmap_region() nullifies vma->vm_file 1544 * before calling this function to clean up. 1545 * Since no pte has actually been setup, it is 1546 * safe to do nothing in this case. 1547 */ 1548 if (vma->vm_file) { 1549 i_mmap_lock_write(vma->vm_file->f_mapping); 1550 __unmap_hugepage_range_final(tlb, vma, start, end, NULL); 1551 i_mmap_unlock_write(vma->vm_file->f_mapping); 1552 } 1553 } else 1554 unmap_page_range(tlb, vma, start, end, details); 1555 } 1556 } 1557 1558 /** 1559 * unmap_vmas - unmap a range of memory covered by a list of vma's 1560 * @tlb: address of the caller's struct mmu_gather 1561 * @vma: the starting vma 1562 * @start_addr: virtual address at which to start unmapping 1563 * @end_addr: virtual address at which to end unmapping 1564 * 1565 * Unmap all pages in the vma list. 1566 * 1567 * Only addresses between `start' and `end' will be unmapped. 1568 * 1569 * The VMA list must be sorted in ascending virtual address order. 1570 * 1571 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1572 * range after unmap_vmas() returns. So the only responsibility here is to 1573 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1574 * drops the lock and schedules. 1575 */ 1576 void unmap_vmas(struct mmu_gather *tlb, 1577 struct vm_area_struct *vma, unsigned long start_addr, 1578 unsigned long end_addr) 1579 { 1580 struct mm_struct *mm = vma->vm_mm; 1581 1582 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1583 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1584 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); 1585 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1586 } 1587 1588 /** 1589 * zap_page_range - remove user pages in a given range 1590 * @vma: vm_area_struct holding the applicable pages 1591 * @start: starting address of pages to zap 1592 * @size: number of bytes to zap 1593 * 1594 * Caller must protect the VMA list 1595 */ 1596 void zap_page_range(struct vm_area_struct *vma, unsigned long start, 1597 unsigned long size) 1598 { 1599 struct mm_struct *mm = vma->vm_mm; 1600 struct mmu_gather tlb; 1601 unsigned long end = start + size; 1602 1603 lru_add_drain(); 1604 tlb_gather_mmu(&tlb, mm, start, end); 1605 update_hiwater_rss(mm); 1606 mmu_notifier_invalidate_range_start(mm, start, end); 1607 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) { 1608 unmap_single_vma(&tlb, vma, start, end, NULL); 1609 1610 /* 1611 * zap_page_range does not specify whether mmap_sem should be 1612 * held for read or write. That allows parallel zap_page_range 1613 * operations to unmap a PTE and defer a flush meaning that 1614 * this call observes pte_none and fails to flush the TLB. 1615 * Rather than adding a complex API, ensure that no stale 1616 * TLB entries exist when this call returns. 1617 */ 1618 flush_tlb_range(vma, start, end); 1619 } 1620 1621 mmu_notifier_invalidate_range_end(mm, start, end); 1622 tlb_finish_mmu(&tlb, start, end); 1623 } 1624 1625 /** 1626 * zap_page_range_single - remove user pages in a given range 1627 * @vma: vm_area_struct holding the applicable pages 1628 * @address: starting address of pages to zap 1629 * @size: number of bytes to zap 1630 * @details: details of shared cache invalidation 1631 * 1632 * The range must fit into one VMA. 1633 */ 1634 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1635 unsigned long size, struct zap_details *details) 1636 { 1637 struct mm_struct *mm = vma->vm_mm; 1638 struct mmu_gather tlb; 1639 unsigned long end = address + size; 1640 1641 lru_add_drain(); 1642 tlb_gather_mmu(&tlb, mm, address, end); 1643 update_hiwater_rss(mm); 1644 mmu_notifier_invalidate_range_start(mm, address, end); 1645 unmap_single_vma(&tlb, vma, address, end, details); 1646 mmu_notifier_invalidate_range_end(mm, address, end); 1647 tlb_finish_mmu(&tlb, address, end); 1648 } 1649 1650 /** 1651 * zap_vma_ptes - remove ptes mapping the vma 1652 * @vma: vm_area_struct holding ptes to be zapped 1653 * @address: starting address of pages to zap 1654 * @size: number of bytes to zap 1655 * 1656 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1657 * 1658 * The entire address range must be fully contained within the vma. 1659 * 1660 * Returns 0 if successful. 1661 */ 1662 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1663 unsigned long size) 1664 { 1665 if (address < vma->vm_start || address + size > vma->vm_end || 1666 !(vma->vm_flags & VM_PFNMAP)) 1667 return -1; 1668 zap_page_range_single(vma, address, size, NULL); 1669 return 0; 1670 } 1671 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1672 1673 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 1674 spinlock_t **ptl) 1675 { 1676 pgd_t *pgd; 1677 p4d_t *p4d; 1678 pud_t *pud; 1679 pmd_t *pmd; 1680 1681 pgd = pgd_offset(mm, addr); 1682 p4d = p4d_alloc(mm, pgd, addr); 1683 if (!p4d) 1684 return NULL; 1685 pud = pud_alloc(mm, p4d, addr); 1686 if (!pud) 1687 return NULL; 1688 pmd = pmd_alloc(mm, pud, addr); 1689 if (!pmd) 1690 return NULL; 1691 1692 VM_BUG_ON(pmd_trans_huge(*pmd)); 1693 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1694 } 1695 1696 /* 1697 * This is the old fallback for page remapping. 1698 * 1699 * For historical reasons, it only allows reserved pages. Only 1700 * old drivers should use this, and they needed to mark their 1701 * pages reserved for the old functions anyway. 1702 */ 1703 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1704 struct page *page, pgprot_t prot) 1705 { 1706 struct mm_struct *mm = vma->vm_mm; 1707 int retval; 1708 pte_t *pte; 1709 spinlock_t *ptl; 1710 1711 retval = -EINVAL; 1712 if (PageAnon(page)) 1713 goto out; 1714 retval = -ENOMEM; 1715 flush_dcache_page(page); 1716 pte = get_locked_pte(mm, addr, &ptl); 1717 if (!pte) 1718 goto out; 1719 retval = -EBUSY; 1720 if (!pte_none(*pte)) 1721 goto out_unlock; 1722 1723 /* Ok, finally just insert the thing.. */ 1724 get_page(page); 1725 inc_mm_counter_fast(mm, mm_counter_file(page)); 1726 page_add_file_rmap(page, false); 1727 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1728 1729 retval = 0; 1730 pte_unmap_unlock(pte, ptl); 1731 return retval; 1732 out_unlock: 1733 pte_unmap_unlock(pte, ptl); 1734 out: 1735 return retval; 1736 } 1737 1738 /** 1739 * vm_insert_page - insert single page into user vma 1740 * @vma: user vma to map to 1741 * @addr: target user address of this page 1742 * @page: source kernel page 1743 * 1744 * This allows drivers to insert individual pages they've allocated 1745 * into a user vma. 1746 * 1747 * The page has to be a nice clean _individual_ kernel allocation. 1748 * If you allocate a compound page, you need to have marked it as 1749 * such (__GFP_COMP), or manually just split the page up yourself 1750 * (see split_page()). 1751 * 1752 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1753 * took an arbitrary page protection parameter. This doesn't allow 1754 * that. Your vma protection will have to be set up correctly, which 1755 * means that if you want a shared writable mapping, you'd better 1756 * ask for a shared writable mapping! 1757 * 1758 * The page does not need to be reserved. 1759 * 1760 * Usually this function is called from f_op->mmap() handler 1761 * under mm->mmap_sem write-lock, so it can change vma->vm_flags. 1762 * Caller must set VM_MIXEDMAP on vma if it wants to call this 1763 * function from other places, for example from page-fault handler. 1764 */ 1765 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1766 struct page *page) 1767 { 1768 if (addr < vma->vm_start || addr >= vma->vm_end) 1769 return -EFAULT; 1770 if (!page_count(page)) 1771 return -EINVAL; 1772 if (!(vma->vm_flags & VM_MIXEDMAP)) { 1773 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); 1774 BUG_ON(vma->vm_flags & VM_PFNMAP); 1775 vma->vm_flags |= VM_MIXEDMAP; 1776 } 1777 return insert_page(vma, addr, page, vma->vm_page_prot); 1778 } 1779 EXPORT_SYMBOL(vm_insert_page); 1780 1781 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1782 pfn_t pfn, pgprot_t prot, bool mkwrite) 1783 { 1784 struct mm_struct *mm = vma->vm_mm; 1785 int retval; 1786 pte_t *pte, entry; 1787 spinlock_t *ptl; 1788 1789 retval = -ENOMEM; 1790 pte = get_locked_pte(mm, addr, &ptl); 1791 if (!pte) 1792 goto out; 1793 retval = -EBUSY; 1794 if (!pte_none(*pte)) { 1795 if (mkwrite) { 1796 /* 1797 * For read faults on private mappings the PFN passed 1798 * in may not match the PFN we have mapped if the 1799 * mapped PFN is a writeable COW page. In the mkwrite 1800 * case we are creating a writable PTE for a shared 1801 * mapping and we expect the PFNs to match. 1802 */ 1803 if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn))) 1804 goto out_unlock; 1805 entry = *pte; 1806 goto out_mkwrite; 1807 } else 1808 goto out_unlock; 1809 } 1810 1811 /* Ok, finally just insert the thing.. */ 1812 if (pfn_t_devmap(pfn)) 1813 entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); 1814 else 1815 entry = pte_mkspecial(pfn_t_pte(pfn, prot)); 1816 1817 out_mkwrite: 1818 if (mkwrite) { 1819 entry = pte_mkyoung(entry); 1820 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1821 } 1822 1823 set_pte_at(mm, addr, pte, entry); 1824 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 1825 1826 retval = 0; 1827 out_unlock: 1828 pte_unmap_unlock(pte, ptl); 1829 out: 1830 return retval; 1831 } 1832 1833 /** 1834 * vm_insert_pfn - insert single pfn into user vma 1835 * @vma: user vma to map to 1836 * @addr: target user address of this page 1837 * @pfn: source kernel pfn 1838 * 1839 * Similar to vm_insert_page, this allows drivers to insert individual pages 1840 * they've allocated into a user vma. Same comments apply. 1841 * 1842 * This function should only be called from a vm_ops->fault handler, and 1843 * in that case the handler should return NULL. 1844 * 1845 * vma cannot be a COW mapping. 1846 * 1847 * As this is called only for pages that do not currently exist, we 1848 * do not need to flush old virtual caches or the TLB. 1849 */ 1850 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1851 unsigned long pfn) 1852 { 1853 return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot); 1854 } 1855 EXPORT_SYMBOL(vm_insert_pfn); 1856 1857 /** 1858 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot 1859 * @vma: user vma to map to 1860 * @addr: target user address of this page 1861 * @pfn: source kernel pfn 1862 * @pgprot: pgprot flags for the inserted page 1863 * 1864 * This is exactly like vm_insert_pfn, except that it allows drivers to 1865 * to override pgprot on a per-page basis. 1866 * 1867 * This only makes sense for IO mappings, and it makes no sense for 1868 * cow mappings. In general, using multiple vmas is preferable; 1869 * vm_insert_pfn_prot should only be used if using multiple VMAs is 1870 * impractical. 1871 */ 1872 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, 1873 unsigned long pfn, pgprot_t pgprot) 1874 { 1875 int ret; 1876 /* 1877 * Technically, architectures with pte_special can avoid all these 1878 * restrictions (same for remap_pfn_range). However we would like 1879 * consistency in testing and feature parity among all, so we should 1880 * try to keep these invariants in place for everybody. 1881 */ 1882 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 1883 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1884 (VM_PFNMAP|VM_MIXEDMAP)); 1885 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1886 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 1887 1888 if (addr < vma->vm_start || addr >= vma->vm_end) 1889 return -EFAULT; 1890 1891 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)); 1892 1893 ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot, 1894 false); 1895 1896 return ret; 1897 } 1898 EXPORT_SYMBOL(vm_insert_pfn_prot); 1899 1900 static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1901 pfn_t pfn, bool mkwrite) 1902 { 1903 pgprot_t pgprot = vma->vm_page_prot; 1904 1905 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 1906 1907 if (addr < vma->vm_start || addr >= vma->vm_end) 1908 return -EFAULT; 1909 1910 track_pfn_insert(vma, &pgprot, pfn); 1911 1912 /* 1913 * If we don't have pte special, then we have to use the pfn_valid() 1914 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 1915 * refcount the page if pfn_valid is true (hence insert_page rather 1916 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 1917 * without pte special, it would there be refcounted as a normal page. 1918 */ 1919 if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) { 1920 struct page *page; 1921 1922 /* 1923 * At this point we are committed to insert_page() 1924 * regardless of whether the caller specified flags that 1925 * result in pfn_t_has_page() == false. 1926 */ 1927 page = pfn_to_page(pfn_t_to_pfn(pfn)); 1928 return insert_page(vma, addr, page, pgprot); 1929 } 1930 return insert_pfn(vma, addr, pfn, pgprot, mkwrite); 1931 } 1932 1933 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1934 pfn_t pfn) 1935 { 1936 return __vm_insert_mixed(vma, addr, pfn, false); 1937 1938 } 1939 EXPORT_SYMBOL(vm_insert_mixed); 1940 1941 int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr, 1942 pfn_t pfn) 1943 { 1944 return __vm_insert_mixed(vma, addr, pfn, true); 1945 } 1946 EXPORT_SYMBOL(vm_insert_mixed_mkwrite); 1947 1948 /* 1949 * maps a range of physical memory into the requested pages. the old 1950 * mappings are removed. any references to nonexistent pages results 1951 * in null mappings (currently treated as "copy-on-access") 1952 */ 1953 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1954 unsigned long addr, unsigned long end, 1955 unsigned long pfn, pgprot_t prot) 1956 { 1957 pte_t *pte; 1958 spinlock_t *ptl; 1959 1960 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1961 if (!pte) 1962 return -ENOMEM; 1963 arch_enter_lazy_mmu_mode(); 1964 do { 1965 BUG_ON(!pte_none(*pte)); 1966 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 1967 pfn++; 1968 } while (pte++, addr += PAGE_SIZE, addr != end); 1969 arch_leave_lazy_mmu_mode(); 1970 pte_unmap_unlock(pte - 1, ptl); 1971 return 0; 1972 } 1973 1974 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1975 unsigned long addr, unsigned long end, 1976 unsigned long pfn, pgprot_t prot) 1977 { 1978 pmd_t *pmd; 1979 unsigned long next; 1980 1981 pfn -= addr >> PAGE_SHIFT; 1982 pmd = pmd_alloc(mm, pud, addr); 1983 if (!pmd) 1984 return -ENOMEM; 1985 VM_BUG_ON(pmd_trans_huge(*pmd)); 1986 do { 1987 next = pmd_addr_end(addr, end); 1988 if (remap_pte_range(mm, pmd, addr, next, 1989 pfn + (addr >> PAGE_SHIFT), prot)) 1990 return -ENOMEM; 1991 } while (pmd++, addr = next, addr != end); 1992 return 0; 1993 } 1994 1995 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d, 1996 unsigned long addr, unsigned long end, 1997 unsigned long pfn, pgprot_t prot) 1998 { 1999 pud_t *pud; 2000 unsigned long next; 2001 2002 pfn -= addr >> PAGE_SHIFT; 2003 pud = pud_alloc(mm, p4d, addr); 2004 if (!pud) 2005 return -ENOMEM; 2006 do { 2007 next = pud_addr_end(addr, end); 2008 if (remap_pmd_range(mm, pud, addr, next, 2009 pfn + (addr >> PAGE_SHIFT), prot)) 2010 return -ENOMEM; 2011 } while (pud++, addr = next, addr != end); 2012 return 0; 2013 } 2014 2015 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd, 2016 unsigned long addr, unsigned long end, 2017 unsigned long pfn, pgprot_t prot) 2018 { 2019 p4d_t *p4d; 2020 unsigned long next; 2021 2022 pfn -= addr >> PAGE_SHIFT; 2023 p4d = p4d_alloc(mm, pgd, addr); 2024 if (!p4d) 2025 return -ENOMEM; 2026 do { 2027 next = p4d_addr_end(addr, end); 2028 if (remap_pud_range(mm, p4d, addr, next, 2029 pfn + (addr >> PAGE_SHIFT), prot)) 2030 return -ENOMEM; 2031 } while (p4d++, addr = next, addr != end); 2032 return 0; 2033 } 2034 2035 /** 2036 * remap_pfn_range - remap kernel memory to userspace 2037 * @vma: user vma to map to 2038 * @addr: target user address to start at 2039 * @pfn: physical address of kernel memory 2040 * @size: size of map area 2041 * @prot: page protection flags for this mapping 2042 * 2043 * Note: this is only safe if the mm semaphore is held when called. 2044 */ 2045 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 2046 unsigned long pfn, unsigned long size, pgprot_t prot) 2047 { 2048 pgd_t *pgd; 2049 unsigned long next; 2050 unsigned long end = addr + PAGE_ALIGN(size); 2051 struct mm_struct *mm = vma->vm_mm; 2052 unsigned long remap_pfn = pfn; 2053 int err; 2054 2055 /* 2056 * Physically remapped pages are special. Tell the 2057 * rest of the world about it: 2058 * VM_IO tells people not to look at these pages 2059 * (accesses can have side effects). 2060 * VM_PFNMAP tells the core MM that the base pages are just 2061 * raw PFN mappings, and do not have a "struct page" associated 2062 * with them. 2063 * VM_DONTEXPAND 2064 * Disable vma merging and expanding with mremap(). 2065 * VM_DONTDUMP 2066 * Omit vma from core dump, even when VM_IO turned off. 2067 * 2068 * There's a horrible special case to handle copy-on-write 2069 * behaviour that some programs depend on. We mark the "original" 2070 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 2071 * See vm_normal_page() for details. 2072 */ 2073 if (is_cow_mapping(vma->vm_flags)) { 2074 if (addr != vma->vm_start || end != vma->vm_end) 2075 return -EINVAL; 2076 vma->vm_pgoff = pfn; 2077 } 2078 2079 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size)); 2080 if (err) 2081 return -EINVAL; 2082 2083 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 2084 2085 BUG_ON(addr >= end); 2086 pfn -= addr >> PAGE_SHIFT; 2087 pgd = pgd_offset(mm, addr); 2088 flush_cache_range(vma, addr, end); 2089 do { 2090 next = pgd_addr_end(addr, end); 2091 err = remap_p4d_range(mm, pgd, addr, next, 2092 pfn + (addr >> PAGE_SHIFT), prot); 2093 if (err) 2094 break; 2095 } while (pgd++, addr = next, addr != end); 2096 2097 if (err) 2098 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size)); 2099 2100 return err; 2101 } 2102 EXPORT_SYMBOL(remap_pfn_range); 2103 2104 /** 2105 * vm_iomap_memory - remap memory to userspace 2106 * @vma: user vma to map to 2107 * @start: start of area 2108 * @len: size of area 2109 * 2110 * This is a simplified io_remap_pfn_range() for common driver use. The 2111 * driver just needs to give us the physical memory range to be mapped, 2112 * we'll figure out the rest from the vma information. 2113 * 2114 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get 2115 * whatever write-combining details or similar. 2116 */ 2117 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 2118 { 2119 unsigned long vm_len, pfn, pages; 2120 2121 /* Check that the physical memory area passed in looks valid */ 2122 if (start + len < start) 2123 return -EINVAL; 2124 /* 2125 * You *really* shouldn't map things that aren't page-aligned, 2126 * but we've historically allowed it because IO memory might 2127 * just have smaller alignment. 2128 */ 2129 len += start & ~PAGE_MASK; 2130 pfn = start >> PAGE_SHIFT; 2131 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; 2132 if (pfn + pages < pfn) 2133 return -EINVAL; 2134 2135 /* We start the mapping 'vm_pgoff' pages into the area */ 2136 if (vma->vm_pgoff > pages) 2137 return -EINVAL; 2138 pfn += vma->vm_pgoff; 2139 pages -= vma->vm_pgoff; 2140 2141 /* Can we fit all of the mapping? */ 2142 vm_len = vma->vm_end - vma->vm_start; 2143 if (vm_len >> PAGE_SHIFT > pages) 2144 return -EINVAL; 2145 2146 /* Ok, let it rip */ 2147 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 2148 } 2149 EXPORT_SYMBOL(vm_iomap_memory); 2150 2151 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 2152 unsigned long addr, unsigned long end, 2153 pte_fn_t fn, void *data) 2154 { 2155 pte_t *pte; 2156 int err; 2157 pgtable_t token; 2158 spinlock_t *uninitialized_var(ptl); 2159 2160 pte = (mm == &init_mm) ? 2161 pte_alloc_kernel(pmd, addr) : 2162 pte_alloc_map_lock(mm, pmd, addr, &ptl); 2163 if (!pte) 2164 return -ENOMEM; 2165 2166 BUG_ON(pmd_huge(*pmd)); 2167 2168 arch_enter_lazy_mmu_mode(); 2169 2170 token = pmd_pgtable(*pmd); 2171 2172 do { 2173 err = fn(pte++, token, addr, data); 2174 if (err) 2175 break; 2176 } while (addr += PAGE_SIZE, addr != end); 2177 2178 arch_leave_lazy_mmu_mode(); 2179 2180 if (mm != &init_mm) 2181 pte_unmap_unlock(pte-1, ptl); 2182 return err; 2183 } 2184 2185 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 2186 unsigned long addr, unsigned long end, 2187 pte_fn_t fn, void *data) 2188 { 2189 pmd_t *pmd; 2190 unsigned long next; 2191 int err; 2192 2193 BUG_ON(pud_huge(*pud)); 2194 2195 pmd = pmd_alloc(mm, pud, addr); 2196 if (!pmd) 2197 return -ENOMEM; 2198 do { 2199 next = pmd_addr_end(addr, end); 2200 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 2201 if (err) 2202 break; 2203 } while (pmd++, addr = next, addr != end); 2204 return err; 2205 } 2206 2207 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d, 2208 unsigned long addr, unsigned long end, 2209 pte_fn_t fn, void *data) 2210 { 2211 pud_t *pud; 2212 unsigned long next; 2213 int err; 2214 2215 pud = pud_alloc(mm, p4d, addr); 2216 if (!pud) 2217 return -ENOMEM; 2218 do { 2219 next = pud_addr_end(addr, end); 2220 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 2221 if (err) 2222 break; 2223 } while (pud++, addr = next, addr != end); 2224 return err; 2225 } 2226 2227 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd, 2228 unsigned long addr, unsigned long end, 2229 pte_fn_t fn, void *data) 2230 { 2231 p4d_t *p4d; 2232 unsigned long next; 2233 int err; 2234 2235 p4d = p4d_alloc(mm, pgd, addr); 2236 if (!p4d) 2237 return -ENOMEM; 2238 do { 2239 next = p4d_addr_end(addr, end); 2240 err = apply_to_pud_range(mm, p4d, addr, next, fn, data); 2241 if (err) 2242 break; 2243 } while (p4d++, addr = next, addr != end); 2244 return err; 2245 } 2246 2247 /* 2248 * Scan a region of virtual memory, filling in page tables as necessary 2249 * and calling a provided function on each leaf page table. 2250 */ 2251 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2252 unsigned long size, pte_fn_t fn, void *data) 2253 { 2254 pgd_t *pgd; 2255 unsigned long next; 2256 unsigned long end = addr + size; 2257 int err; 2258 2259 if (WARN_ON(addr >= end)) 2260 return -EINVAL; 2261 2262 pgd = pgd_offset(mm, addr); 2263 do { 2264 next = pgd_addr_end(addr, end); 2265 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data); 2266 if (err) 2267 break; 2268 } while (pgd++, addr = next, addr != end); 2269 2270 return err; 2271 } 2272 EXPORT_SYMBOL_GPL(apply_to_page_range); 2273 2274 /* 2275 * handle_pte_fault chooses page fault handler according to an entry which was 2276 * read non-atomically. Before making any commitment, on those architectures 2277 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched 2278 * parts, do_swap_page must check under lock before unmapping the pte and 2279 * proceeding (but do_wp_page is only called after already making such a check; 2280 * and do_anonymous_page can safely check later on). 2281 */ 2282 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 2283 pte_t *page_table, pte_t orig_pte) 2284 { 2285 int same = 1; 2286 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 2287 if (sizeof(pte_t) > sizeof(unsigned long)) { 2288 spinlock_t *ptl = pte_lockptr(mm, pmd); 2289 spin_lock(ptl); 2290 same = pte_same(*page_table, orig_pte); 2291 spin_unlock(ptl); 2292 } 2293 #endif 2294 pte_unmap(page_table); 2295 return same; 2296 } 2297 2298 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 2299 { 2300 debug_dma_assert_idle(src); 2301 2302 /* 2303 * If the source page was a PFN mapping, we don't have 2304 * a "struct page" for it. We do a best-effort copy by 2305 * just copying from the original user address. If that 2306 * fails, we just zero-fill it. Live with it. 2307 */ 2308 if (unlikely(!src)) { 2309 void *kaddr = kmap_atomic(dst); 2310 void __user *uaddr = (void __user *)(va & PAGE_MASK); 2311 2312 /* 2313 * This really shouldn't fail, because the page is there 2314 * in the page tables. But it might just be unreadable, 2315 * in which case we just give up and fill the result with 2316 * zeroes. 2317 */ 2318 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 2319 clear_page(kaddr); 2320 kunmap_atomic(kaddr); 2321 flush_dcache_page(dst); 2322 } else 2323 copy_user_highpage(dst, src, va, vma); 2324 } 2325 2326 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma) 2327 { 2328 struct file *vm_file = vma->vm_file; 2329 2330 if (vm_file) 2331 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO; 2332 2333 /* 2334 * Special mappings (e.g. VDSO) do not have any file so fake 2335 * a default GFP_KERNEL for them. 2336 */ 2337 return GFP_KERNEL; 2338 } 2339 2340 /* 2341 * Notify the address space that the page is about to become writable so that 2342 * it can prohibit this or wait for the page to get into an appropriate state. 2343 * 2344 * We do this without the lock held, so that it can sleep if it needs to. 2345 */ 2346 static int do_page_mkwrite(struct vm_fault *vmf) 2347 { 2348 int ret; 2349 struct page *page = vmf->page; 2350 unsigned int old_flags = vmf->flags; 2351 2352 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2353 2354 ret = vmf->vma->vm_ops->page_mkwrite(vmf); 2355 /* Restore original flags so that caller is not surprised */ 2356 vmf->flags = old_flags; 2357 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2358 return ret; 2359 if (unlikely(!(ret & VM_FAULT_LOCKED))) { 2360 lock_page(page); 2361 if (!page->mapping) { 2362 unlock_page(page); 2363 return 0; /* retry */ 2364 } 2365 ret |= VM_FAULT_LOCKED; 2366 } else 2367 VM_BUG_ON_PAGE(!PageLocked(page), page); 2368 return ret; 2369 } 2370 2371 /* 2372 * Handle dirtying of a page in shared file mapping on a write fault. 2373 * 2374 * The function expects the page to be locked and unlocks it. 2375 */ 2376 static void fault_dirty_shared_page(struct vm_area_struct *vma, 2377 struct page *page) 2378 { 2379 struct address_space *mapping; 2380 bool dirtied; 2381 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite; 2382 2383 dirtied = set_page_dirty(page); 2384 VM_BUG_ON_PAGE(PageAnon(page), page); 2385 /* 2386 * Take a local copy of the address_space - page.mapping may be zeroed 2387 * by truncate after unlock_page(). The address_space itself remains 2388 * pinned by vma->vm_file's reference. We rely on unlock_page()'s 2389 * release semantics to prevent the compiler from undoing this copying. 2390 */ 2391 mapping = page_rmapping(page); 2392 unlock_page(page); 2393 2394 if ((dirtied || page_mkwrite) && mapping) { 2395 /* 2396 * Some device drivers do not set page.mapping 2397 * but still dirty their pages 2398 */ 2399 balance_dirty_pages_ratelimited(mapping); 2400 } 2401 2402 if (!page_mkwrite) 2403 file_update_time(vma->vm_file); 2404 } 2405 2406 /* 2407 * Handle write page faults for pages that can be reused in the current vma 2408 * 2409 * This can happen either due to the mapping being with the VM_SHARED flag, 2410 * or due to us being the last reference standing to the page. In either 2411 * case, all we need to do here is to mark the page as writable and update 2412 * any related book-keeping. 2413 */ 2414 static inline void wp_page_reuse(struct vm_fault *vmf) 2415 __releases(vmf->ptl) 2416 { 2417 struct vm_area_struct *vma = vmf->vma; 2418 struct page *page = vmf->page; 2419 pte_t entry; 2420 /* 2421 * Clear the pages cpupid information as the existing 2422 * information potentially belongs to a now completely 2423 * unrelated process. 2424 */ 2425 if (page) 2426 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1); 2427 2428 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); 2429 entry = pte_mkyoung(vmf->orig_pte); 2430 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2431 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1)) 2432 update_mmu_cache(vma, vmf->address, vmf->pte); 2433 pte_unmap_unlock(vmf->pte, vmf->ptl); 2434 } 2435 2436 /* 2437 * Handle the case of a page which we actually need to copy to a new page. 2438 * 2439 * Called with mmap_sem locked and the old page referenced, but 2440 * without the ptl held. 2441 * 2442 * High level logic flow: 2443 * 2444 * - Allocate a page, copy the content of the old page to the new one. 2445 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc. 2446 * - Take the PTL. If the pte changed, bail out and release the allocated page 2447 * - If the pte is still the way we remember it, update the page table and all 2448 * relevant references. This includes dropping the reference the page-table 2449 * held to the old page, as well as updating the rmap. 2450 * - In any case, unlock the PTL and drop the reference we took to the old page. 2451 */ 2452 static int wp_page_copy(struct vm_fault *vmf) 2453 { 2454 struct vm_area_struct *vma = vmf->vma; 2455 struct mm_struct *mm = vma->vm_mm; 2456 struct page *old_page = vmf->page; 2457 struct page *new_page = NULL; 2458 pte_t entry; 2459 int page_copied = 0; 2460 const unsigned long mmun_start = vmf->address & PAGE_MASK; 2461 const unsigned long mmun_end = mmun_start + PAGE_SIZE; 2462 struct mem_cgroup *memcg; 2463 2464 if (unlikely(anon_vma_prepare(vma))) 2465 goto oom; 2466 2467 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) { 2468 new_page = alloc_zeroed_user_highpage_movable(vma, 2469 vmf->address); 2470 if (!new_page) 2471 goto oom; 2472 } else { 2473 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, 2474 vmf->address); 2475 if (!new_page) 2476 goto oom; 2477 cow_user_page(new_page, old_page, vmf->address, vma); 2478 } 2479 2480 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false)) 2481 goto oom_free_new; 2482 2483 __SetPageUptodate(new_page); 2484 2485 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2486 2487 /* 2488 * Re-check the pte - we dropped the lock 2489 */ 2490 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl); 2491 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) { 2492 if (old_page) { 2493 if (!PageAnon(old_page)) { 2494 dec_mm_counter_fast(mm, 2495 mm_counter_file(old_page)); 2496 inc_mm_counter_fast(mm, MM_ANONPAGES); 2497 } 2498 } else { 2499 inc_mm_counter_fast(mm, MM_ANONPAGES); 2500 } 2501 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); 2502 entry = mk_pte(new_page, vma->vm_page_prot); 2503 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2504 /* 2505 * Clear the pte entry and flush it first, before updating the 2506 * pte with the new entry. This will avoid a race condition 2507 * seen in the presence of one thread doing SMC and another 2508 * thread doing COW. 2509 */ 2510 ptep_clear_flush_notify(vma, vmf->address, vmf->pte); 2511 page_add_new_anon_rmap(new_page, vma, vmf->address, false); 2512 mem_cgroup_commit_charge(new_page, memcg, false, false); 2513 lru_cache_add_active_or_unevictable(new_page, vma); 2514 /* 2515 * We call the notify macro here because, when using secondary 2516 * mmu page tables (such as kvm shadow page tables), we want the 2517 * new page to be mapped directly into the secondary page table. 2518 */ 2519 set_pte_at_notify(mm, vmf->address, vmf->pte, entry); 2520 update_mmu_cache(vma, vmf->address, vmf->pte); 2521 if (old_page) { 2522 /* 2523 * Only after switching the pte to the new page may 2524 * we remove the mapcount here. Otherwise another 2525 * process may come and find the rmap count decremented 2526 * before the pte is switched to the new page, and 2527 * "reuse" the old page writing into it while our pte 2528 * here still points into it and can be read by other 2529 * threads. 2530 * 2531 * The critical issue is to order this 2532 * page_remove_rmap with the ptp_clear_flush above. 2533 * Those stores are ordered by (if nothing else,) 2534 * the barrier present in the atomic_add_negative 2535 * in page_remove_rmap. 2536 * 2537 * Then the TLB flush in ptep_clear_flush ensures that 2538 * no process can access the old page before the 2539 * decremented mapcount is visible. And the old page 2540 * cannot be reused until after the decremented 2541 * mapcount is visible. So transitively, TLBs to 2542 * old page will be flushed before it can be reused. 2543 */ 2544 page_remove_rmap(old_page, false); 2545 } 2546 2547 /* Free the old page.. */ 2548 new_page = old_page; 2549 page_copied = 1; 2550 } else { 2551 mem_cgroup_cancel_charge(new_page, memcg, false); 2552 } 2553 2554 if (new_page) 2555 put_page(new_page); 2556 2557 pte_unmap_unlock(vmf->pte, vmf->ptl); 2558 /* 2559 * No need to double call mmu_notifier->invalidate_range() callback as 2560 * the above ptep_clear_flush_notify() did already call it. 2561 */ 2562 mmu_notifier_invalidate_range_only_end(mm, mmun_start, mmun_end); 2563 if (old_page) { 2564 /* 2565 * Don't let another task, with possibly unlocked vma, 2566 * keep the mlocked page. 2567 */ 2568 if (page_copied && (vma->vm_flags & VM_LOCKED)) { 2569 lock_page(old_page); /* LRU manipulation */ 2570 if (PageMlocked(old_page)) 2571 munlock_vma_page(old_page); 2572 unlock_page(old_page); 2573 } 2574 put_page(old_page); 2575 } 2576 return page_copied ? VM_FAULT_WRITE : 0; 2577 oom_free_new: 2578 put_page(new_page); 2579 oom: 2580 if (old_page) 2581 put_page(old_page); 2582 return VM_FAULT_OOM; 2583 } 2584 2585 /** 2586 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE 2587 * writeable once the page is prepared 2588 * 2589 * @vmf: structure describing the fault 2590 * 2591 * This function handles all that is needed to finish a write page fault in a 2592 * shared mapping due to PTE being read-only once the mapped page is prepared. 2593 * It handles locking of PTE and modifying it. The function returns 2594 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE 2595 * lock. 2596 * 2597 * The function expects the page to be locked or other protection against 2598 * concurrent faults / writeback (such as DAX radix tree locks). 2599 */ 2600 int finish_mkwrite_fault(struct vm_fault *vmf) 2601 { 2602 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED)); 2603 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address, 2604 &vmf->ptl); 2605 /* 2606 * We might have raced with another page fault while we released the 2607 * pte_offset_map_lock. 2608 */ 2609 if (!pte_same(*vmf->pte, vmf->orig_pte)) { 2610 pte_unmap_unlock(vmf->pte, vmf->ptl); 2611 return VM_FAULT_NOPAGE; 2612 } 2613 wp_page_reuse(vmf); 2614 return 0; 2615 } 2616 2617 /* 2618 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED 2619 * mapping 2620 */ 2621 static int wp_pfn_shared(struct vm_fault *vmf) 2622 { 2623 struct vm_area_struct *vma = vmf->vma; 2624 2625 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) { 2626 int ret; 2627 2628 pte_unmap_unlock(vmf->pte, vmf->ptl); 2629 vmf->flags |= FAULT_FLAG_MKWRITE; 2630 ret = vma->vm_ops->pfn_mkwrite(vmf); 2631 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)) 2632 return ret; 2633 return finish_mkwrite_fault(vmf); 2634 } 2635 wp_page_reuse(vmf); 2636 return VM_FAULT_WRITE; 2637 } 2638 2639 static int wp_page_shared(struct vm_fault *vmf) 2640 __releases(vmf->ptl) 2641 { 2642 struct vm_area_struct *vma = vmf->vma; 2643 2644 get_page(vmf->page); 2645 2646 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2647 int tmp; 2648 2649 pte_unmap_unlock(vmf->pte, vmf->ptl); 2650 tmp = do_page_mkwrite(vmf); 2651 if (unlikely(!tmp || (tmp & 2652 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 2653 put_page(vmf->page); 2654 return tmp; 2655 } 2656 tmp = finish_mkwrite_fault(vmf); 2657 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2658 unlock_page(vmf->page); 2659 put_page(vmf->page); 2660 return tmp; 2661 } 2662 } else { 2663 wp_page_reuse(vmf); 2664 lock_page(vmf->page); 2665 } 2666 fault_dirty_shared_page(vma, vmf->page); 2667 put_page(vmf->page); 2668 2669 return VM_FAULT_WRITE; 2670 } 2671 2672 /* 2673 * This routine handles present pages, when users try to write 2674 * to a shared page. It is done by copying the page to a new address 2675 * and decrementing the shared-page counter for the old page. 2676 * 2677 * Note that this routine assumes that the protection checks have been 2678 * done by the caller (the low-level page fault routine in most cases). 2679 * Thus we can safely just mark it writable once we've done any necessary 2680 * COW. 2681 * 2682 * We also mark the page dirty at this point even though the page will 2683 * change only once the write actually happens. This avoids a few races, 2684 * and potentially makes it more efficient. 2685 * 2686 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2687 * but allow concurrent faults), with pte both mapped and locked. 2688 * We return with mmap_sem still held, but pte unmapped and unlocked. 2689 */ 2690 static int do_wp_page(struct vm_fault *vmf) 2691 __releases(vmf->ptl) 2692 { 2693 struct vm_area_struct *vma = vmf->vma; 2694 2695 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte); 2696 if (!vmf->page) { 2697 /* 2698 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a 2699 * VM_PFNMAP VMA. 2700 * 2701 * We should not cow pages in a shared writeable mapping. 2702 * Just mark the pages writable and/or call ops->pfn_mkwrite. 2703 */ 2704 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2705 (VM_WRITE|VM_SHARED)) 2706 return wp_pfn_shared(vmf); 2707 2708 pte_unmap_unlock(vmf->pte, vmf->ptl); 2709 return wp_page_copy(vmf); 2710 } 2711 2712 /* 2713 * Take out anonymous pages first, anonymous shared vmas are 2714 * not dirty accountable. 2715 */ 2716 if (PageAnon(vmf->page) && !PageKsm(vmf->page)) { 2717 int total_map_swapcount; 2718 if (!trylock_page(vmf->page)) { 2719 get_page(vmf->page); 2720 pte_unmap_unlock(vmf->pte, vmf->ptl); 2721 lock_page(vmf->page); 2722 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 2723 vmf->address, &vmf->ptl); 2724 if (!pte_same(*vmf->pte, vmf->orig_pte)) { 2725 unlock_page(vmf->page); 2726 pte_unmap_unlock(vmf->pte, vmf->ptl); 2727 put_page(vmf->page); 2728 return 0; 2729 } 2730 put_page(vmf->page); 2731 } 2732 if (reuse_swap_page(vmf->page, &total_map_swapcount)) { 2733 if (total_map_swapcount == 1) { 2734 /* 2735 * The page is all ours. Move it to 2736 * our anon_vma so the rmap code will 2737 * not search our parent or siblings. 2738 * Protected against the rmap code by 2739 * the page lock. 2740 */ 2741 page_move_anon_rmap(vmf->page, vma); 2742 } 2743 unlock_page(vmf->page); 2744 wp_page_reuse(vmf); 2745 return VM_FAULT_WRITE; 2746 } 2747 unlock_page(vmf->page); 2748 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2749 (VM_WRITE|VM_SHARED))) { 2750 return wp_page_shared(vmf); 2751 } 2752 2753 /* 2754 * Ok, we need to copy. Oh, well.. 2755 */ 2756 get_page(vmf->page); 2757 2758 pte_unmap_unlock(vmf->pte, vmf->ptl); 2759 return wp_page_copy(vmf); 2760 } 2761 2762 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 2763 unsigned long start_addr, unsigned long end_addr, 2764 struct zap_details *details) 2765 { 2766 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 2767 } 2768 2769 static inline void unmap_mapping_range_tree(struct rb_root_cached *root, 2770 struct zap_details *details) 2771 { 2772 struct vm_area_struct *vma; 2773 pgoff_t vba, vea, zba, zea; 2774 2775 vma_interval_tree_foreach(vma, root, 2776 details->first_index, details->last_index) { 2777 2778 vba = vma->vm_pgoff; 2779 vea = vba + vma_pages(vma) - 1; 2780 zba = details->first_index; 2781 if (zba < vba) 2782 zba = vba; 2783 zea = details->last_index; 2784 if (zea > vea) 2785 zea = vea; 2786 2787 unmap_mapping_range_vma(vma, 2788 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2789 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2790 details); 2791 } 2792 } 2793 2794 /** 2795 * unmap_mapping_range - unmap the portion of all mmaps in the specified 2796 * address_space corresponding to the specified page range in the underlying 2797 * file. 2798 * 2799 * @mapping: the address space containing mmaps to be unmapped. 2800 * @holebegin: byte in first page to unmap, relative to the start of 2801 * the underlying file. This will be rounded down to a PAGE_SIZE 2802 * boundary. Note that this is different from truncate_pagecache(), which 2803 * must keep the partial page. In contrast, we must get rid of 2804 * partial pages. 2805 * @holelen: size of prospective hole in bytes. This will be rounded 2806 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2807 * end of the file. 2808 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2809 * but 0 when invalidating pagecache, don't throw away private data. 2810 */ 2811 void unmap_mapping_range(struct address_space *mapping, 2812 loff_t const holebegin, loff_t const holelen, int even_cows) 2813 { 2814 struct zap_details details = { }; 2815 pgoff_t hba = holebegin >> PAGE_SHIFT; 2816 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2817 2818 /* Check for overflow. */ 2819 if (sizeof(holelen) > sizeof(hlen)) { 2820 long long holeend = 2821 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2822 if (holeend & ~(long long)ULONG_MAX) 2823 hlen = ULONG_MAX - hba + 1; 2824 } 2825 2826 details.check_mapping = even_cows ? NULL : mapping; 2827 details.first_index = hba; 2828 details.last_index = hba + hlen - 1; 2829 if (details.last_index < details.first_index) 2830 details.last_index = ULONG_MAX; 2831 2832 i_mmap_lock_write(mapping); 2833 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))) 2834 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2835 i_mmap_unlock_write(mapping); 2836 } 2837 EXPORT_SYMBOL(unmap_mapping_range); 2838 2839 /* 2840 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2841 * but allow concurrent faults), and pte mapped but not yet locked. 2842 * We return with pte unmapped and unlocked. 2843 * 2844 * We return with the mmap_sem locked or unlocked in the same cases 2845 * as does filemap_fault(). 2846 */ 2847 int do_swap_page(struct vm_fault *vmf) 2848 { 2849 struct vm_area_struct *vma = vmf->vma; 2850 struct page *page = NULL, *swapcache = NULL; 2851 struct mem_cgroup *memcg; 2852 struct vma_swap_readahead swap_ra; 2853 swp_entry_t entry; 2854 pte_t pte; 2855 int locked; 2856 int exclusive = 0; 2857 int ret = 0; 2858 bool vma_readahead = swap_use_vma_readahead(); 2859 2860 if (vma_readahead) 2861 page = swap_readahead_detect(vmf, &swap_ra); 2862 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte)) { 2863 if (page) 2864 put_page(page); 2865 goto out; 2866 } 2867 2868 entry = pte_to_swp_entry(vmf->orig_pte); 2869 if (unlikely(non_swap_entry(entry))) { 2870 if (is_migration_entry(entry)) { 2871 migration_entry_wait(vma->vm_mm, vmf->pmd, 2872 vmf->address); 2873 } else if (is_device_private_entry(entry)) { 2874 /* 2875 * For un-addressable device memory we call the pgmap 2876 * fault handler callback. The callback must migrate 2877 * the page back to some CPU accessible page. 2878 */ 2879 ret = device_private_entry_fault(vma, vmf->address, entry, 2880 vmf->flags, vmf->pmd); 2881 } else if (is_hwpoison_entry(entry)) { 2882 ret = VM_FAULT_HWPOISON; 2883 } else { 2884 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL); 2885 ret = VM_FAULT_SIGBUS; 2886 } 2887 goto out; 2888 } 2889 2890 2891 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2892 if (!page) 2893 page = lookup_swap_cache(entry, vma_readahead ? vma : NULL, 2894 vmf->address); 2895 if (!page) { 2896 struct swap_info_struct *si = swp_swap_info(entry); 2897 2898 if (si->flags & SWP_SYNCHRONOUS_IO && 2899 __swap_count(si, entry) == 1) { 2900 /* skip swapcache */ 2901 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); 2902 if (page) { 2903 __SetPageLocked(page); 2904 __SetPageSwapBacked(page); 2905 set_page_private(page, entry.val); 2906 lru_cache_add_anon(page); 2907 swap_readpage(page, true); 2908 } 2909 } else { 2910 if (vma_readahead) 2911 page = do_swap_page_readahead(entry, 2912 GFP_HIGHUSER_MOVABLE, vmf, &swap_ra); 2913 else 2914 page = swapin_readahead(entry, 2915 GFP_HIGHUSER_MOVABLE, vma, vmf->address); 2916 swapcache = page; 2917 } 2918 2919 if (!page) { 2920 /* 2921 * Back out if somebody else faulted in this pte 2922 * while we released the pte lock. 2923 */ 2924 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 2925 vmf->address, &vmf->ptl); 2926 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) 2927 ret = VM_FAULT_OOM; 2928 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2929 goto unlock; 2930 } 2931 2932 /* Had to read the page from swap area: Major fault */ 2933 ret = VM_FAULT_MAJOR; 2934 count_vm_event(PGMAJFAULT); 2935 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT); 2936 } else if (PageHWPoison(page)) { 2937 /* 2938 * hwpoisoned dirty swapcache pages are kept for killing 2939 * owner processes (which may be unknown at hwpoison time) 2940 */ 2941 ret = VM_FAULT_HWPOISON; 2942 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2943 swapcache = page; 2944 goto out_release; 2945 } 2946 2947 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags); 2948 2949 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2950 if (!locked) { 2951 ret |= VM_FAULT_RETRY; 2952 goto out_release; 2953 } 2954 2955 /* 2956 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 2957 * release the swapcache from under us. The page pin, and pte_same 2958 * test below, are not enough to exclude that. Even if it is still 2959 * swapcache, we need to check that the page's swap has not changed. 2960 */ 2961 if (unlikely((!PageSwapCache(page) || 2962 page_private(page) != entry.val)) && swapcache) 2963 goto out_page; 2964 2965 page = ksm_might_need_to_copy(page, vma, vmf->address); 2966 if (unlikely(!page)) { 2967 ret = VM_FAULT_OOM; 2968 page = swapcache; 2969 goto out_page; 2970 } 2971 2972 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, 2973 &memcg, false)) { 2974 ret = VM_FAULT_OOM; 2975 goto out_page; 2976 } 2977 2978 /* 2979 * Back out if somebody else already faulted in this pte. 2980 */ 2981 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 2982 &vmf->ptl); 2983 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) 2984 goto out_nomap; 2985 2986 if (unlikely(!PageUptodate(page))) { 2987 ret = VM_FAULT_SIGBUS; 2988 goto out_nomap; 2989 } 2990 2991 /* 2992 * The page isn't present yet, go ahead with the fault. 2993 * 2994 * Be careful about the sequence of operations here. 2995 * To get its accounting right, reuse_swap_page() must be called 2996 * while the page is counted on swap but not yet in mapcount i.e. 2997 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2998 * must be called after the swap_free(), or it will never succeed. 2999 */ 3000 3001 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3002 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS); 3003 pte = mk_pte(page, vma->vm_page_prot); 3004 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) { 3005 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 3006 vmf->flags &= ~FAULT_FLAG_WRITE; 3007 ret |= VM_FAULT_WRITE; 3008 exclusive = RMAP_EXCLUSIVE; 3009 } 3010 flush_icache_page(vma, page); 3011 if (pte_swp_soft_dirty(vmf->orig_pte)) 3012 pte = pte_mksoft_dirty(pte); 3013 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte); 3014 vmf->orig_pte = pte; 3015 3016 /* ksm created a completely new copy */ 3017 if (unlikely(page != swapcache && swapcache)) { 3018 page_add_new_anon_rmap(page, vma, vmf->address, false); 3019 mem_cgroup_commit_charge(page, memcg, false, false); 3020 lru_cache_add_active_or_unevictable(page, vma); 3021 } else { 3022 do_page_add_anon_rmap(page, vma, vmf->address, exclusive); 3023 mem_cgroup_commit_charge(page, memcg, true, false); 3024 activate_page(page); 3025 } 3026 3027 swap_free(entry); 3028 if (mem_cgroup_swap_full(page) || 3029 (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 3030 try_to_free_swap(page); 3031 unlock_page(page); 3032 if (page != swapcache && swapcache) { 3033 /* 3034 * Hold the lock to avoid the swap entry to be reused 3035 * until we take the PT lock for the pte_same() check 3036 * (to avoid false positives from pte_same). For 3037 * further safety release the lock after the swap_free 3038 * so that the swap count won't change under a 3039 * parallel locked swapcache. 3040 */ 3041 unlock_page(swapcache); 3042 put_page(swapcache); 3043 } 3044 3045 if (vmf->flags & FAULT_FLAG_WRITE) { 3046 ret |= do_wp_page(vmf); 3047 if (ret & VM_FAULT_ERROR) 3048 ret &= VM_FAULT_ERROR; 3049 goto out; 3050 } 3051 3052 /* No need to invalidate - it was non-present before */ 3053 update_mmu_cache(vma, vmf->address, vmf->pte); 3054 unlock: 3055 pte_unmap_unlock(vmf->pte, vmf->ptl); 3056 out: 3057 return ret; 3058 out_nomap: 3059 mem_cgroup_cancel_charge(page, memcg, false); 3060 pte_unmap_unlock(vmf->pte, vmf->ptl); 3061 out_page: 3062 unlock_page(page); 3063 out_release: 3064 put_page(page); 3065 if (page != swapcache && swapcache) { 3066 unlock_page(swapcache); 3067 put_page(swapcache); 3068 } 3069 return ret; 3070 } 3071 3072 /* 3073 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3074 * but allow concurrent faults), and pte mapped but not yet locked. 3075 * We return with mmap_sem still held, but pte unmapped and unlocked. 3076 */ 3077 static int do_anonymous_page(struct vm_fault *vmf) 3078 { 3079 struct vm_area_struct *vma = vmf->vma; 3080 struct mem_cgroup *memcg; 3081 struct page *page; 3082 int ret = 0; 3083 pte_t entry; 3084 3085 /* File mapping without ->vm_ops ? */ 3086 if (vma->vm_flags & VM_SHARED) 3087 return VM_FAULT_SIGBUS; 3088 3089 /* 3090 * Use pte_alloc() instead of pte_alloc_map(). We can't run 3091 * pte_offset_map() on pmds where a huge pmd might be created 3092 * from a different thread. 3093 * 3094 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when 3095 * parallel threads are excluded by other means. 3096 * 3097 * Here we only have down_read(mmap_sem). 3098 */ 3099 if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address)) 3100 return VM_FAULT_OOM; 3101 3102 /* See the comment in pte_alloc_one_map() */ 3103 if (unlikely(pmd_trans_unstable(vmf->pmd))) 3104 return 0; 3105 3106 /* Use the zero-page for reads */ 3107 if (!(vmf->flags & FAULT_FLAG_WRITE) && 3108 !mm_forbids_zeropage(vma->vm_mm)) { 3109 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address), 3110 vma->vm_page_prot)); 3111 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, 3112 vmf->address, &vmf->ptl); 3113 if (!pte_none(*vmf->pte)) 3114 goto unlock; 3115 ret = check_stable_address_space(vma->vm_mm); 3116 if (ret) 3117 goto unlock; 3118 /* Deliver the page fault to userland, check inside PT lock */ 3119 if (userfaultfd_missing(vma)) { 3120 pte_unmap_unlock(vmf->pte, vmf->ptl); 3121 return handle_userfault(vmf, VM_UFFD_MISSING); 3122 } 3123 goto setpte; 3124 } 3125 3126 /* Allocate our own private page. */ 3127 if (unlikely(anon_vma_prepare(vma))) 3128 goto oom; 3129 page = alloc_zeroed_user_highpage_movable(vma, vmf->address); 3130 if (!page) 3131 goto oom; 3132 3133 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false)) 3134 goto oom_free_page; 3135 3136 /* 3137 * The memory barrier inside __SetPageUptodate makes sure that 3138 * preceeding stores to the page contents become visible before 3139 * the set_pte_at() write. 3140 */ 3141 __SetPageUptodate(page); 3142 3143 entry = mk_pte(page, vma->vm_page_prot); 3144 if (vma->vm_flags & VM_WRITE) 3145 entry = pte_mkwrite(pte_mkdirty(entry)); 3146 3147 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 3148 &vmf->ptl); 3149 if (!pte_none(*vmf->pte)) 3150 goto release; 3151 3152 ret = check_stable_address_space(vma->vm_mm); 3153 if (ret) 3154 goto release; 3155 3156 /* Deliver the page fault to userland, check inside PT lock */ 3157 if (userfaultfd_missing(vma)) { 3158 pte_unmap_unlock(vmf->pte, vmf->ptl); 3159 mem_cgroup_cancel_charge(page, memcg, false); 3160 put_page(page); 3161 return handle_userfault(vmf, VM_UFFD_MISSING); 3162 } 3163 3164 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3165 page_add_new_anon_rmap(page, vma, vmf->address, false); 3166 mem_cgroup_commit_charge(page, memcg, false, false); 3167 lru_cache_add_active_or_unevictable(page, vma); 3168 setpte: 3169 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); 3170 3171 /* No need to invalidate - it was non-present before */ 3172 update_mmu_cache(vma, vmf->address, vmf->pte); 3173 unlock: 3174 pte_unmap_unlock(vmf->pte, vmf->ptl); 3175 return ret; 3176 release: 3177 mem_cgroup_cancel_charge(page, memcg, false); 3178 put_page(page); 3179 goto unlock; 3180 oom_free_page: 3181 put_page(page); 3182 oom: 3183 return VM_FAULT_OOM; 3184 } 3185 3186 /* 3187 * The mmap_sem must have been held on entry, and may have been 3188 * released depending on flags and vma->vm_ops->fault() return value. 3189 * See filemap_fault() and __lock_page_retry(). 3190 */ 3191 static int __do_fault(struct vm_fault *vmf) 3192 { 3193 struct vm_area_struct *vma = vmf->vma; 3194 int ret; 3195 3196 ret = vma->vm_ops->fault(vmf); 3197 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY | 3198 VM_FAULT_DONE_COW))) 3199 return ret; 3200 3201 if (unlikely(PageHWPoison(vmf->page))) { 3202 if (ret & VM_FAULT_LOCKED) 3203 unlock_page(vmf->page); 3204 put_page(vmf->page); 3205 vmf->page = NULL; 3206 return VM_FAULT_HWPOISON; 3207 } 3208 3209 if (unlikely(!(ret & VM_FAULT_LOCKED))) 3210 lock_page(vmf->page); 3211 else 3212 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page); 3213 3214 return ret; 3215 } 3216 3217 /* 3218 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set. 3219 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check 3220 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly 3221 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output. 3222 */ 3223 static int pmd_devmap_trans_unstable(pmd_t *pmd) 3224 { 3225 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd); 3226 } 3227 3228 static int pte_alloc_one_map(struct vm_fault *vmf) 3229 { 3230 struct vm_area_struct *vma = vmf->vma; 3231 3232 if (!pmd_none(*vmf->pmd)) 3233 goto map_pte; 3234 if (vmf->prealloc_pte) { 3235 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 3236 if (unlikely(!pmd_none(*vmf->pmd))) { 3237 spin_unlock(vmf->ptl); 3238 goto map_pte; 3239 } 3240 3241 mm_inc_nr_ptes(vma->vm_mm); 3242 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); 3243 spin_unlock(vmf->ptl); 3244 vmf->prealloc_pte = NULL; 3245 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) { 3246 return VM_FAULT_OOM; 3247 } 3248 map_pte: 3249 /* 3250 * If a huge pmd materialized under us just retry later. Use 3251 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of 3252 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge 3253 * under us and then back to pmd_none, as a result of MADV_DONTNEED 3254 * running immediately after a huge pmd fault in a different thread of 3255 * this mm, in turn leading to a misleading pmd_trans_huge() retval. 3256 * All we have to ensure is that it is a regular pmd that we can walk 3257 * with pte_offset_map() and we can do that through an atomic read in 3258 * C, which is what pmd_trans_unstable() provides. 3259 */ 3260 if (pmd_devmap_trans_unstable(vmf->pmd)) 3261 return VM_FAULT_NOPAGE; 3262 3263 /* 3264 * At this point we know that our vmf->pmd points to a page of ptes 3265 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge() 3266 * for the duration of the fault. If a racing MADV_DONTNEED runs and 3267 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still 3268 * be valid and we will re-check to make sure the vmf->pte isn't 3269 * pte_none() under vmf->ptl protection when we return to 3270 * alloc_set_pte(). 3271 */ 3272 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address, 3273 &vmf->ptl); 3274 return 0; 3275 } 3276 3277 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE 3278 3279 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1) 3280 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma, 3281 unsigned long haddr) 3282 { 3283 if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) != 3284 (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK)) 3285 return false; 3286 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end) 3287 return false; 3288 return true; 3289 } 3290 3291 static void deposit_prealloc_pte(struct vm_fault *vmf) 3292 { 3293 struct vm_area_struct *vma = vmf->vma; 3294 3295 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte); 3296 /* 3297 * We are going to consume the prealloc table, 3298 * count that as nr_ptes. 3299 */ 3300 mm_inc_nr_ptes(vma->vm_mm); 3301 vmf->prealloc_pte = NULL; 3302 } 3303 3304 static int do_set_pmd(struct vm_fault *vmf, struct page *page) 3305 { 3306 struct vm_area_struct *vma = vmf->vma; 3307 bool write = vmf->flags & FAULT_FLAG_WRITE; 3308 unsigned long haddr = vmf->address & HPAGE_PMD_MASK; 3309 pmd_t entry; 3310 int i, ret; 3311 3312 if (!transhuge_vma_suitable(vma, haddr)) 3313 return VM_FAULT_FALLBACK; 3314 3315 ret = VM_FAULT_FALLBACK; 3316 page = compound_head(page); 3317 3318 /* 3319 * Archs like ppc64 need additonal space to store information 3320 * related to pte entry. Use the preallocated table for that. 3321 */ 3322 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) { 3323 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address); 3324 if (!vmf->prealloc_pte) 3325 return VM_FAULT_OOM; 3326 smp_wmb(); /* See comment in __pte_alloc() */ 3327 } 3328 3329 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd); 3330 if (unlikely(!pmd_none(*vmf->pmd))) 3331 goto out; 3332 3333 for (i = 0; i < HPAGE_PMD_NR; i++) 3334 flush_icache_page(vma, page + i); 3335 3336 entry = mk_huge_pmd(page, vma->vm_page_prot); 3337 if (write) 3338 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); 3339 3340 add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR); 3341 page_add_file_rmap(page, true); 3342 /* 3343 * deposit and withdraw with pmd lock held 3344 */ 3345 if (arch_needs_pgtable_deposit()) 3346 deposit_prealloc_pte(vmf); 3347 3348 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry); 3349 3350 update_mmu_cache_pmd(vma, haddr, vmf->pmd); 3351 3352 /* fault is handled */ 3353 ret = 0; 3354 count_vm_event(THP_FILE_MAPPED); 3355 out: 3356 spin_unlock(vmf->ptl); 3357 return ret; 3358 } 3359 #else 3360 static int do_set_pmd(struct vm_fault *vmf, struct page *page) 3361 { 3362 BUILD_BUG(); 3363 return 0; 3364 } 3365 #endif 3366 3367 /** 3368 * alloc_set_pte - setup new PTE entry for given page and add reverse page 3369 * mapping. If needed, the fucntion allocates page table or use pre-allocated. 3370 * 3371 * @vmf: fault environment 3372 * @memcg: memcg to charge page (only for private mappings) 3373 * @page: page to map 3374 * 3375 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on 3376 * return. 3377 * 3378 * Target users are page handler itself and implementations of 3379 * vm_ops->map_pages. 3380 */ 3381 int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg, 3382 struct page *page) 3383 { 3384 struct vm_area_struct *vma = vmf->vma; 3385 bool write = vmf->flags & FAULT_FLAG_WRITE; 3386 pte_t entry; 3387 int ret; 3388 3389 if (pmd_none(*vmf->pmd) && PageTransCompound(page) && 3390 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) { 3391 /* THP on COW? */ 3392 VM_BUG_ON_PAGE(memcg, page); 3393 3394 ret = do_set_pmd(vmf, page); 3395 if (ret != VM_FAULT_FALLBACK) 3396 return ret; 3397 } 3398 3399 if (!vmf->pte) { 3400 ret = pte_alloc_one_map(vmf); 3401 if (ret) 3402 return ret; 3403 } 3404 3405 /* Re-check under ptl */ 3406 if (unlikely(!pte_none(*vmf->pte))) 3407 return VM_FAULT_NOPAGE; 3408 3409 flush_icache_page(vma, page); 3410 entry = mk_pte(page, vma->vm_page_prot); 3411 if (write) 3412 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3413 /* copy-on-write page */ 3414 if (write && !(vma->vm_flags & VM_SHARED)) { 3415 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3416 page_add_new_anon_rmap(page, vma, vmf->address, false); 3417 mem_cgroup_commit_charge(page, memcg, false, false); 3418 lru_cache_add_active_or_unevictable(page, vma); 3419 } else { 3420 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page)); 3421 page_add_file_rmap(page, false); 3422 } 3423 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry); 3424 3425 /* no need to invalidate: a not-present page won't be cached */ 3426 update_mmu_cache(vma, vmf->address, vmf->pte); 3427 3428 return 0; 3429 } 3430 3431 3432 /** 3433 * finish_fault - finish page fault once we have prepared the page to fault 3434 * 3435 * @vmf: structure describing the fault 3436 * 3437 * This function handles all that is needed to finish a page fault once the 3438 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for 3439 * given page, adds reverse page mapping, handles memcg charges and LRU 3440 * addition. The function returns 0 on success, VM_FAULT_ code in case of 3441 * error. 3442 * 3443 * The function expects the page to be locked and on success it consumes a 3444 * reference of a page being mapped (for the PTE which maps it). 3445 */ 3446 int finish_fault(struct vm_fault *vmf) 3447 { 3448 struct page *page; 3449 int ret = 0; 3450 3451 /* Did we COW the page? */ 3452 if ((vmf->flags & FAULT_FLAG_WRITE) && 3453 !(vmf->vma->vm_flags & VM_SHARED)) 3454 page = vmf->cow_page; 3455 else 3456 page = vmf->page; 3457 3458 /* 3459 * check even for read faults because we might have lost our CoWed 3460 * page 3461 */ 3462 if (!(vmf->vma->vm_flags & VM_SHARED)) 3463 ret = check_stable_address_space(vmf->vma->vm_mm); 3464 if (!ret) 3465 ret = alloc_set_pte(vmf, vmf->memcg, page); 3466 if (vmf->pte) 3467 pte_unmap_unlock(vmf->pte, vmf->ptl); 3468 return ret; 3469 } 3470 3471 static unsigned long fault_around_bytes __read_mostly = 3472 rounddown_pow_of_two(65536); 3473 3474 #ifdef CONFIG_DEBUG_FS 3475 static int fault_around_bytes_get(void *data, u64 *val) 3476 { 3477 *val = fault_around_bytes; 3478 return 0; 3479 } 3480 3481 /* 3482 * fault_around_pages() and fault_around_mask() expects fault_around_bytes 3483 * rounded down to nearest page order. It's what do_fault_around() expects to 3484 * see. 3485 */ 3486 static int fault_around_bytes_set(void *data, u64 val) 3487 { 3488 if (val / PAGE_SIZE > PTRS_PER_PTE) 3489 return -EINVAL; 3490 if (val > PAGE_SIZE) 3491 fault_around_bytes = rounddown_pow_of_two(val); 3492 else 3493 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */ 3494 return 0; 3495 } 3496 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops, 3497 fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); 3498 3499 static int __init fault_around_debugfs(void) 3500 { 3501 void *ret; 3502 3503 ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL, 3504 &fault_around_bytes_fops); 3505 if (!ret) 3506 pr_warn("Failed to create fault_around_bytes in debugfs"); 3507 return 0; 3508 } 3509 late_initcall(fault_around_debugfs); 3510 #endif 3511 3512 /* 3513 * do_fault_around() tries to map few pages around the fault address. The hope 3514 * is that the pages will be needed soon and this will lower the number of 3515 * faults to handle. 3516 * 3517 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's 3518 * not ready to be mapped: not up-to-date, locked, etc. 3519 * 3520 * This function is called with the page table lock taken. In the split ptlock 3521 * case the page table lock only protects only those entries which belong to 3522 * the page table corresponding to the fault address. 3523 * 3524 * This function doesn't cross the VMA boundaries, in order to call map_pages() 3525 * only once. 3526 * 3527 * fault_around_pages() defines how many pages we'll try to map. 3528 * do_fault_around() expects it to return a power of two less than or equal to 3529 * PTRS_PER_PTE. 3530 * 3531 * The virtual address of the area that we map is naturally aligned to the 3532 * fault_around_pages() value (and therefore to page order). This way it's 3533 * easier to guarantee that we don't cross page table boundaries. 3534 */ 3535 static int do_fault_around(struct vm_fault *vmf) 3536 { 3537 unsigned long address = vmf->address, nr_pages, mask; 3538 pgoff_t start_pgoff = vmf->pgoff; 3539 pgoff_t end_pgoff; 3540 int off, ret = 0; 3541 3542 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT; 3543 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK; 3544 3545 vmf->address = max(address & mask, vmf->vma->vm_start); 3546 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); 3547 start_pgoff -= off; 3548 3549 /* 3550 * end_pgoff is either end of page table or end of vma 3551 * or fault_around_pages() from start_pgoff, depending what is nearest. 3552 */ 3553 end_pgoff = start_pgoff - 3554 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + 3555 PTRS_PER_PTE - 1; 3556 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1, 3557 start_pgoff + nr_pages - 1); 3558 3559 if (pmd_none(*vmf->pmd)) { 3560 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm, 3561 vmf->address); 3562 if (!vmf->prealloc_pte) 3563 goto out; 3564 smp_wmb(); /* See comment in __pte_alloc() */ 3565 } 3566 3567 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff); 3568 3569 /* Huge page is mapped? Page fault is solved */ 3570 if (pmd_trans_huge(*vmf->pmd)) { 3571 ret = VM_FAULT_NOPAGE; 3572 goto out; 3573 } 3574 3575 /* ->map_pages() haven't done anything useful. Cold page cache? */ 3576 if (!vmf->pte) 3577 goto out; 3578 3579 /* check if the page fault is solved */ 3580 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT); 3581 if (!pte_none(*vmf->pte)) 3582 ret = VM_FAULT_NOPAGE; 3583 pte_unmap_unlock(vmf->pte, vmf->ptl); 3584 out: 3585 vmf->address = address; 3586 vmf->pte = NULL; 3587 return ret; 3588 } 3589 3590 static int do_read_fault(struct vm_fault *vmf) 3591 { 3592 struct vm_area_struct *vma = vmf->vma; 3593 int ret = 0; 3594 3595 /* 3596 * Let's call ->map_pages() first and use ->fault() as fallback 3597 * if page by the offset is not ready to be mapped (cold cache or 3598 * something). 3599 */ 3600 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) { 3601 ret = do_fault_around(vmf); 3602 if (ret) 3603 return ret; 3604 } 3605 3606 ret = __do_fault(vmf); 3607 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3608 return ret; 3609 3610 ret |= finish_fault(vmf); 3611 unlock_page(vmf->page); 3612 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3613 put_page(vmf->page); 3614 return ret; 3615 } 3616 3617 static int do_cow_fault(struct vm_fault *vmf) 3618 { 3619 struct vm_area_struct *vma = vmf->vma; 3620 int ret; 3621 3622 if (unlikely(anon_vma_prepare(vma))) 3623 return VM_FAULT_OOM; 3624 3625 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); 3626 if (!vmf->cow_page) 3627 return VM_FAULT_OOM; 3628 3629 if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL, 3630 &vmf->memcg, false)) { 3631 put_page(vmf->cow_page); 3632 return VM_FAULT_OOM; 3633 } 3634 3635 ret = __do_fault(vmf); 3636 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3637 goto uncharge_out; 3638 if (ret & VM_FAULT_DONE_COW) 3639 return ret; 3640 3641 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma); 3642 __SetPageUptodate(vmf->cow_page); 3643 3644 ret |= finish_fault(vmf); 3645 unlock_page(vmf->page); 3646 put_page(vmf->page); 3647 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3648 goto uncharge_out; 3649 return ret; 3650 uncharge_out: 3651 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false); 3652 put_page(vmf->cow_page); 3653 return ret; 3654 } 3655 3656 static int do_shared_fault(struct vm_fault *vmf) 3657 { 3658 struct vm_area_struct *vma = vmf->vma; 3659 int ret, tmp; 3660 3661 ret = __do_fault(vmf); 3662 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3663 return ret; 3664 3665 /* 3666 * Check if the backing address space wants to know that the page is 3667 * about to become writable 3668 */ 3669 if (vma->vm_ops->page_mkwrite) { 3670 unlock_page(vmf->page); 3671 tmp = do_page_mkwrite(vmf); 3672 if (unlikely(!tmp || 3673 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 3674 put_page(vmf->page); 3675 return tmp; 3676 } 3677 } 3678 3679 ret |= finish_fault(vmf); 3680 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | 3681 VM_FAULT_RETRY))) { 3682 unlock_page(vmf->page); 3683 put_page(vmf->page); 3684 return ret; 3685 } 3686 3687 fault_dirty_shared_page(vma, vmf->page); 3688 return ret; 3689 } 3690 3691 /* 3692 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3693 * but allow concurrent faults). 3694 * The mmap_sem may have been released depending on flags and our 3695 * return value. See filemap_fault() and __lock_page_or_retry(). 3696 */ 3697 static int do_fault(struct vm_fault *vmf) 3698 { 3699 struct vm_area_struct *vma = vmf->vma; 3700 int ret; 3701 3702 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */ 3703 if (!vma->vm_ops->fault) 3704 ret = VM_FAULT_SIGBUS; 3705 else if (!(vmf->flags & FAULT_FLAG_WRITE)) 3706 ret = do_read_fault(vmf); 3707 else if (!(vma->vm_flags & VM_SHARED)) 3708 ret = do_cow_fault(vmf); 3709 else 3710 ret = do_shared_fault(vmf); 3711 3712 /* preallocated pagetable is unused: free it */ 3713 if (vmf->prealloc_pte) { 3714 pte_free(vma->vm_mm, vmf->prealloc_pte); 3715 vmf->prealloc_pte = NULL; 3716 } 3717 return ret; 3718 } 3719 3720 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, 3721 unsigned long addr, int page_nid, 3722 int *flags) 3723 { 3724 get_page(page); 3725 3726 count_vm_numa_event(NUMA_HINT_FAULTS); 3727 if (page_nid == numa_node_id()) { 3728 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 3729 *flags |= TNF_FAULT_LOCAL; 3730 } 3731 3732 return mpol_misplaced(page, vma, addr); 3733 } 3734 3735 static int do_numa_page(struct vm_fault *vmf) 3736 { 3737 struct vm_area_struct *vma = vmf->vma; 3738 struct page *page = NULL; 3739 int page_nid = -1; 3740 int last_cpupid; 3741 int target_nid; 3742 bool migrated = false; 3743 pte_t pte; 3744 bool was_writable = pte_savedwrite(vmf->orig_pte); 3745 int flags = 0; 3746 3747 /* 3748 * The "pte" at this point cannot be used safely without 3749 * validation through pte_unmap_same(). It's of NUMA type but 3750 * the pfn may be screwed if the read is non atomic. 3751 */ 3752 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd); 3753 spin_lock(vmf->ptl); 3754 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) { 3755 pte_unmap_unlock(vmf->pte, vmf->ptl); 3756 goto out; 3757 } 3758 3759 /* 3760 * Make it present again, Depending on how arch implementes non 3761 * accessible ptes, some can allow access by kernel mode. 3762 */ 3763 pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte); 3764 pte = pte_modify(pte, vma->vm_page_prot); 3765 pte = pte_mkyoung(pte); 3766 if (was_writable) 3767 pte = pte_mkwrite(pte); 3768 ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte); 3769 update_mmu_cache(vma, vmf->address, vmf->pte); 3770 3771 page = vm_normal_page(vma, vmf->address, pte); 3772 if (!page) { 3773 pte_unmap_unlock(vmf->pte, vmf->ptl); 3774 return 0; 3775 } 3776 3777 /* TODO: handle PTE-mapped THP */ 3778 if (PageCompound(page)) { 3779 pte_unmap_unlock(vmf->pte, vmf->ptl); 3780 return 0; 3781 } 3782 3783 /* 3784 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as 3785 * much anyway since they can be in shared cache state. This misses 3786 * the case where a mapping is writable but the process never writes 3787 * to it but pte_write gets cleared during protection updates and 3788 * pte_dirty has unpredictable behaviour between PTE scan updates, 3789 * background writeback, dirty balancing and application behaviour. 3790 */ 3791 if (!pte_write(pte)) 3792 flags |= TNF_NO_GROUP; 3793 3794 /* 3795 * Flag if the page is shared between multiple address spaces. This 3796 * is later used when determining whether to group tasks together 3797 */ 3798 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) 3799 flags |= TNF_SHARED; 3800 3801 last_cpupid = page_cpupid_last(page); 3802 page_nid = page_to_nid(page); 3803 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid, 3804 &flags); 3805 pte_unmap_unlock(vmf->pte, vmf->ptl); 3806 if (target_nid == -1) { 3807 put_page(page); 3808 goto out; 3809 } 3810 3811 /* Migrate to the requested node */ 3812 migrated = migrate_misplaced_page(page, vma, target_nid); 3813 if (migrated) { 3814 page_nid = target_nid; 3815 flags |= TNF_MIGRATED; 3816 } else 3817 flags |= TNF_MIGRATE_FAIL; 3818 3819 out: 3820 if (page_nid != -1) 3821 task_numa_fault(last_cpupid, page_nid, 1, flags); 3822 return 0; 3823 } 3824 3825 static inline int create_huge_pmd(struct vm_fault *vmf) 3826 { 3827 if (vma_is_anonymous(vmf->vma)) 3828 return do_huge_pmd_anonymous_page(vmf); 3829 if (vmf->vma->vm_ops->huge_fault) 3830 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); 3831 return VM_FAULT_FALLBACK; 3832 } 3833 3834 /* `inline' is required to avoid gcc 4.1.2 build error */ 3835 static inline int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd) 3836 { 3837 if (vma_is_anonymous(vmf->vma)) 3838 return do_huge_pmd_wp_page(vmf, orig_pmd); 3839 if (vmf->vma->vm_ops->huge_fault) 3840 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); 3841 3842 /* COW handled on pte level: split pmd */ 3843 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma); 3844 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL); 3845 3846 return VM_FAULT_FALLBACK; 3847 } 3848 3849 static inline bool vma_is_accessible(struct vm_area_struct *vma) 3850 { 3851 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE); 3852 } 3853 3854 static int create_huge_pud(struct vm_fault *vmf) 3855 { 3856 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 3857 /* No support for anonymous transparent PUD pages yet */ 3858 if (vma_is_anonymous(vmf->vma)) 3859 return VM_FAULT_FALLBACK; 3860 if (vmf->vma->vm_ops->huge_fault) 3861 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); 3862 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 3863 return VM_FAULT_FALLBACK; 3864 } 3865 3866 static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) 3867 { 3868 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 3869 /* No support for anonymous transparent PUD pages yet */ 3870 if (vma_is_anonymous(vmf->vma)) 3871 return VM_FAULT_FALLBACK; 3872 if (vmf->vma->vm_ops->huge_fault) 3873 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); 3874 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 3875 return VM_FAULT_FALLBACK; 3876 } 3877 3878 /* 3879 * These routines also need to handle stuff like marking pages dirty 3880 * and/or accessed for architectures that don't do it in hardware (most 3881 * RISC architectures). The early dirtying is also good on the i386. 3882 * 3883 * There is also a hook called "update_mmu_cache()" that architectures 3884 * with external mmu caches can use to update those (ie the Sparc or 3885 * PowerPC hashed page tables that act as extended TLBs). 3886 * 3887 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow 3888 * concurrent faults). 3889 * 3890 * The mmap_sem may have been released depending on flags and our return value. 3891 * See filemap_fault() and __lock_page_or_retry(). 3892 */ 3893 static int handle_pte_fault(struct vm_fault *vmf) 3894 { 3895 pte_t entry; 3896 3897 if (unlikely(pmd_none(*vmf->pmd))) { 3898 /* 3899 * Leave __pte_alloc() until later: because vm_ops->fault may 3900 * want to allocate huge page, and if we expose page table 3901 * for an instant, it will be difficult to retract from 3902 * concurrent faults and from rmap lookups. 3903 */ 3904 vmf->pte = NULL; 3905 } else { 3906 /* See comment in pte_alloc_one_map() */ 3907 if (pmd_devmap_trans_unstable(vmf->pmd)) 3908 return 0; 3909 /* 3910 * A regular pmd is established and it can't morph into a huge 3911 * pmd from under us anymore at this point because we hold the 3912 * mmap_sem read mode and khugepaged takes it in write mode. 3913 * So now it's safe to run pte_offset_map(). 3914 */ 3915 vmf->pte = pte_offset_map(vmf->pmd, vmf->address); 3916 vmf->orig_pte = *vmf->pte; 3917 3918 /* 3919 * some architectures can have larger ptes than wordsize, 3920 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and 3921 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic 3922 * accesses. The code below just needs a consistent view 3923 * for the ifs and we later double check anyway with the 3924 * ptl lock held. So here a barrier will do. 3925 */ 3926 barrier(); 3927 if (pte_none(vmf->orig_pte)) { 3928 pte_unmap(vmf->pte); 3929 vmf->pte = NULL; 3930 } 3931 } 3932 3933 if (!vmf->pte) { 3934 if (vma_is_anonymous(vmf->vma)) 3935 return do_anonymous_page(vmf); 3936 else 3937 return do_fault(vmf); 3938 } 3939 3940 if (!pte_present(vmf->orig_pte)) 3941 return do_swap_page(vmf); 3942 3943 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma)) 3944 return do_numa_page(vmf); 3945 3946 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd); 3947 spin_lock(vmf->ptl); 3948 entry = vmf->orig_pte; 3949 if (unlikely(!pte_same(*vmf->pte, entry))) 3950 goto unlock; 3951 if (vmf->flags & FAULT_FLAG_WRITE) { 3952 if (!pte_write(entry)) 3953 return do_wp_page(vmf); 3954 entry = pte_mkdirty(entry); 3955 } 3956 entry = pte_mkyoung(entry); 3957 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry, 3958 vmf->flags & FAULT_FLAG_WRITE)) { 3959 update_mmu_cache(vmf->vma, vmf->address, vmf->pte); 3960 } else { 3961 /* 3962 * This is needed only for protection faults but the arch code 3963 * is not yet telling us if this is a protection fault or not. 3964 * This still avoids useless tlb flushes for .text page faults 3965 * with threads. 3966 */ 3967 if (vmf->flags & FAULT_FLAG_WRITE) 3968 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address); 3969 } 3970 unlock: 3971 pte_unmap_unlock(vmf->pte, vmf->ptl); 3972 return 0; 3973 } 3974 3975 /* 3976 * By the time we get here, we already hold the mm semaphore 3977 * 3978 * The mmap_sem may have been released depending on flags and our 3979 * return value. See filemap_fault() and __lock_page_or_retry(). 3980 */ 3981 static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address, 3982 unsigned int flags) 3983 { 3984 struct vm_fault vmf = { 3985 .vma = vma, 3986 .address = address & PAGE_MASK, 3987 .flags = flags, 3988 .pgoff = linear_page_index(vma, address), 3989 .gfp_mask = __get_fault_gfp_mask(vma), 3990 }; 3991 unsigned int dirty = flags & FAULT_FLAG_WRITE; 3992 struct mm_struct *mm = vma->vm_mm; 3993 pgd_t *pgd; 3994 p4d_t *p4d; 3995 int ret; 3996 3997 pgd = pgd_offset(mm, address); 3998 p4d = p4d_alloc(mm, pgd, address); 3999 if (!p4d) 4000 return VM_FAULT_OOM; 4001 4002 vmf.pud = pud_alloc(mm, p4d, address); 4003 if (!vmf.pud) 4004 return VM_FAULT_OOM; 4005 if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) { 4006 ret = create_huge_pud(&vmf); 4007 if (!(ret & VM_FAULT_FALLBACK)) 4008 return ret; 4009 } else { 4010 pud_t orig_pud = *vmf.pud; 4011 4012 barrier(); 4013 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) { 4014 4015 /* NUMA case for anonymous PUDs would go here */ 4016 4017 if (dirty && !pud_write(orig_pud)) { 4018 ret = wp_huge_pud(&vmf, orig_pud); 4019 if (!(ret & VM_FAULT_FALLBACK)) 4020 return ret; 4021 } else { 4022 huge_pud_set_accessed(&vmf, orig_pud); 4023 return 0; 4024 } 4025 } 4026 } 4027 4028 vmf.pmd = pmd_alloc(mm, vmf.pud, address); 4029 if (!vmf.pmd) 4030 return VM_FAULT_OOM; 4031 if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) { 4032 ret = create_huge_pmd(&vmf); 4033 if (!(ret & VM_FAULT_FALLBACK)) 4034 return ret; 4035 } else { 4036 pmd_t orig_pmd = *vmf.pmd; 4037 4038 barrier(); 4039 if (unlikely(is_swap_pmd(orig_pmd))) { 4040 VM_BUG_ON(thp_migration_supported() && 4041 !is_pmd_migration_entry(orig_pmd)); 4042 if (is_pmd_migration_entry(orig_pmd)) 4043 pmd_migration_entry_wait(mm, vmf.pmd); 4044 return 0; 4045 } 4046 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) { 4047 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma)) 4048 return do_huge_pmd_numa_page(&vmf, orig_pmd); 4049 4050 if (dirty && !pmd_write(orig_pmd)) { 4051 ret = wp_huge_pmd(&vmf, orig_pmd); 4052 if (!(ret & VM_FAULT_FALLBACK)) 4053 return ret; 4054 } else { 4055 huge_pmd_set_accessed(&vmf, orig_pmd); 4056 return 0; 4057 } 4058 } 4059 } 4060 4061 return handle_pte_fault(&vmf); 4062 } 4063 4064 /* 4065 * By the time we get here, we already hold the mm semaphore 4066 * 4067 * The mmap_sem may have been released depending on flags and our 4068 * return value. See filemap_fault() and __lock_page_or_retry(). 4069 */ 4070 int handle_mm_fault(struct vm_area_struct *vma, unsigned long address, 4071 unsigned int flags) 4072 { 4073 int ret; 4074 4075 __set_current_state(TASK_RUNNING); 4076 4077 count_vm_event(PGFAULT); 4078 count_memcg_event_mm(vma->vm_mm, PGFAULT); 4079 4080 /* do counter updates before entering really critical section. */ 4081 check_sync_rss_stat(current); 4082 4083 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, 4084 flags & FAULT_FLAG_INSTRUCTION, 4085 flags & FAULT_FLAG_REMOTE)) 4086 return VM_FAULT_SIGSEGV; 4087 4088 /* 4089 * Enable the memcg OOM handling for faults triggered in user 4090 * space. Kernel faults are handled more gracefully. 4091 */ 4092 if (flags & FAULT_FLAG_USER) 4093 mem_cgroup_oom_enable(); 4094 4095 if (unlikely(is_vm_hugetlb_page(vma))) 4096 ret = hugetlb_fault(vma->vm_mm, vma, address, flags); 4097 else 4098 ret = __handle_mm_fault(vma, address, flags); 4099 4100 if (flags & FAULT_FLAG_USER) { 4101 mem_cgroup_oom_disable(); 4102 /* 4103 * The task may have entered a memcg OOM situation but 4104 * if the allocation error was handled gracefully (no 4105 * VM_FAULT_OOM), there is no need to kill anything. 4106 * Just clean up the OOM state peacefully. 4107 */ 4108 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) 4109 mem_cgroup_oom_synchronize(false); 4110 } 4111 4112 return ret; 4113 } 4114 EXPORT_SYMBOL_GPL(handle_mm_fault); 4115 4116 #ifndef __PAGETABLE_P4D_FOLDED 4117 /* 4118 * Allocate p4d page table. 4119 * We've already handled the fast-path in-line. 4120 */ 4121 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 4122 { 4123 p4d_t *new = p4d_alloc_one(mm, address); 4124 if (!new) 4125 return -ENOMEM; 4126 4127 smp_wmb(); /* See comment in __pte_alloc */ 4128 4129 spin_lock(&mm->page_table_lock); 4130 if (pgd_present(*pgd)) /* Another has populated it */ 4131 p4d_free(mm, new); 4132 else 4133 pgd_populate(mm, pgd, new); 4134 spin_unlock(&mm->page_table_lock); 4135 return 0; 4136 } 4137 #endif /* __PAGETABLE_P4D_FOLDED */ 4138 4139 #ifndef __PAGETABLE_PUD_FOLDED 4140 /* 4141 * Allocate page upper directory. 4142 * We've already handled the fast-path in-line. 4143 */ 4144 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address) 4145 { 4146 pud_t *new = pud_alloc_one(mm, address); 4147 if (!new) 4148 return -ENOMEM; 4149 4150 smp_wmb(); /* See comment in __pte_alloc */ 4151 4152 spin_lock(&mm->page_table_lock); 4153 #ifndef __ARCH_HAS_5LEVEL_HACK 4154 if (!p4d_present(*p4d)) { 4155 mm_inc_nr_puds(mm); 4156 p4d_populate(mm, p4d, new); 4157 } else /* Another has populated it */ 4158 pud_free(mm, new); 4159 #else 4160 if (!pgd_present(*p4d)) { 4161 mm_inc_nr_puds(mm); 4162 pgd_populate(mm, p4d, new); 4163 } else /* Another has populated it */ 4164 pud_free(mm, new); 4165 #endif /* __ARCH_HAS_5LEVEL_HACK */ 4166 spin_unlock(&mm->page_table_lock); 4167 return 0; 4168 } 4169 #endif /* __PAGETABLE_PUD_FOLDED */ 4170 4171 #ifndef __PAGETABLE_PMD_FOLDED 4172 /* 4173 * Allocate page middle directory. 4174 * We've already handled the fast-path in-line. 4175 */ 4176 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 4177 { 4178 spinlock_t *ptl; 4179 pmd_t *new = pmd_alloc_one(mm, address); 4180 if (!new) 4181 return -ENOMEM; 4182 4183 smp_wmb(); /* See comment in __pte_alloc */ 4184 4185 ptl = pud_lock(mm, pud); 4186 #ifndef __ARCH_HAS_4LEVEL_HACK 4187 if (!pud_present(*pud)) { 4188 mm_inc_nr_pmds(mm); 4189 pud_populate(mm, pud, new); 4190 } else /* Another has populated it */ 4191 pmd_free(mm, new); 4192 #else 4193 if (!pgd_present(*pud)) { 4194 mm_inc_nr_pmds(mm); 4195 pgd_populate(mm, pud, new); 4196 } else /* Another has populated it */ 4197 pmd_free(mm, new); 4198 #endif /* __ARCH_HAS_4LEVEL_HACK */ 4199 spin_unlock(ptl); 4200 return 0; 4201 } 4202 #endif /* __PAGETABLE_PMD_FOLDED */ 4203 4204 static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address, 4205 unsigned long *start, unsigned long *end, 4206 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) 4207 { 4208 pgd_t *pgd; 4209 p4d_t *p4d; 4210 pud_t *pud; 4211 pmd_t *pmd; 4212 pte_t *ptep; 4213 4214 pgd = pgd_offset(mm, address); 4215 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 4216 goto out; 4217 4218 p4d = p4d_offset(pgd, address); 4219 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d))) 4220 goto out; 4221 4222 pud = pud_offset(p4d, address); 4223 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 4224 goto out; 4225 4226 pmd = pmd_offset(pud, address); 4227 VM_BUG_ON(pmd_trans_huge(*pmd)); 4228 4229 if (pmd_huge(*pmd)) { 4230 if (!pmdpp) 4231 goto out; 4232 4233 if (start && end) { 4234 *start = address & PMD_MASK; 4235 *end = *start + PMD_SIZE; 4236 mmu_notifier_invalidate_range_start(mm, *start, *end); 4237 } 4238 *ptlp = pmd_lock(mm, pmd); 4239 if (pmd_huge(*pmd)) { 4240 *pmdpp = pmd; 4241 return 0; 4242 } 4243 spin_unlock(*ptlp); 4244 if (start && end) 4245 mmu_notifier_invalidate_range_end(mm, *start, *end); 4246 } 4247 4248 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 4249 goto out; 4250 4251 if (start && end) { 4252 *start = address & PAGE_MASK; 4253 *end = *start + PAGE_SIZE; 4254 mmu_notifier_invalidate_range_start(mm, *start, *end); 4255 } 4256 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 4257 if (!pte_present(*ptep)) 4258 goto unlock; 4259 *ptepp = ptep; 4260 return 0; 4261 unlock: 4262 pte_unmap_unlock(ptep, *ptlp); 4263 if (start && end) 4264 mmu_notifier_invalidate_range_end(mm, *start, *end); 4265 out: 4266 return -EINVAL; 4267 } 4268 4269 static inline int follow_pte(struct mm_struct *mm, unsigned long address, 4270 pte_t **ptepp, spinlock_t **ptlp) 4271 { 4272 int res; 4273 4274 /* (void) is needed to make gcc happy */ 4275 (void) __cond_lock(*ptlp, 4276 !(res = __follow_pte_pmd(mm, address, NULL, NULL, 4277 ptepp, NULL, ptlp))); 4278 return res; 4279 } 4280 4281 int follow_pte_pmd(struct mm_struct *mm, unsigned long address, 4282 unsigned long *start, unsigned long *end, 4283 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp) 4284 { 4285 int res; 4286 4287 /* (void) is needed to make gcc happy */ 4288 (void) __cond_lock(*ptlp, 4289 !(res = __follow_pte_pmd(mm, address, start, end, 4290 ptepp, pmdpp, ptlp))); 4291 return res; 4292 } 4293 EXPORT_SYMBOL(follow_pte_pmd); 4294 4295 /** 4296 * follow_pfn - look up PFN at a user virtual address 4297 * @vma: memory mapping 4298 * @address: user virtual address 4299 * @pfn: location to store found PFN 4300 * 4301 * Only IO mappings and raw PFN mappings are allowed. 4302 * 4303 * Returns zero and the pfn at @pfn on success, -ve otherwise. 4304 */ 4305 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 4306 unsigned long *pfn) 4307 { 4308 int ret = -EINVAL; 4309 spinlock_t *ptl; 4310 pte_t *ptep; 4311 4312 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4313 return ret; 4314 4315 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 4316 if (ret) 4317 return ret; 4318 *pfn = pte_pfn(*ptep); 4319 pte_unmap_unlock(ptep, ptl); 4320 return 0; 4321 } 4322 EXPORT_SYMBOL(follow_pfn); 4323 4324 #ifdef CONFIG_HAVE_IOREMAP_PROT 4325 int follow_phys(struct vm_area_struct *vma, 4326 unsigned long address, unsigned int flags, 4327 unsigned long *prot, resource_size_t *phys) 4328 { 4329 int ret = -EINVAL; 4330 pte_t *ptep, pte; 4331 spinlock_t *ptl; 4332 4333 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4334 goto out; 4335 4336 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 4337 goto out; 4338 pte = *ptep; 4339 4340 if ((flags & FOLL_WRITE) && !pte_write(pte)) 4341 goto unlock; 4342 4343 *prot = pgprot_val(pte_pgprot(pte)); 4344 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 4345 4346 ret = 0; 4347 unlock: 4348 pte_unmap_unlock(ptep, ptl); 4349 out: 4350 return ret; 4351 } 4352 4353 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 4354 void *buf, int len, int write) 4355 { 4356 resource_size_t phys_addr; 4357 unsigned long prot = 0; 4358 void __iomem *maddr; 4359 int offset = addr & (PAGE_SIZE-1); 4360 4361 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 4362 return -EINVAL; 4363 4364 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot); 4365 if (write) 4366 memcpy_toio(maddr + offset, buf, len); 4367 else 4368 memcpy_fromio(buf, maddr + offset, len); 4369 iounmap(maddr); 4370 4371 return len; 4372 } 4373 EXPORT_SYMBOL_GPL(generic_access_phys); 4374 #endif 4375 4376 /* 4377 * Access another process' address space as given in mm. If non-NULL, use the 4378 * given task for page fault accounting. 4379 */ 4380 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 4381 unsigned long addr, void *buf, int len, unsigned int gup_flags) 4382 { 4383 struct vm_area_struct *vma; 4384 void *old_buf = buf; 4385 int write = gup_flags & FOLL_WRITE; 4386 4387 down_read(&mm->mmap_sem); 4388 /* ignore errors, just check how much was successfully transferred */ 4389 while (len) { 4390 int bytes, ret, offset; 4391 void *maddr; 4392 struct page *page = NULL; 4393 4394 ret = get_user_pages_remote(tsk, mm, addr, 1, 4395 gup_flags, &page, &vma, NULL); 4396 if (ret <= 0) { 4397 #ifndef CONFIG_HAVE_IOREMAP_PROT 4398 break; 4399 #else 4400 /* 4401 * Check if this is a VM_IO | VM_PFNMAP VMA, which 4402 * we can access using slightly different code. 4403 */ 4404 vma = find_vma(mm, addr); 4405 if (!vma || vma->vm_start > addr) 4406 break; 4407 if (vma->vm_ops && vma->vm_ops->access) 4408 ret = vma->vm_ops->access(vma, addr, buf, 4409 len, write); 4410 if (ret <= 0) 4411 break; 4412 bytes = ret; 4413 #endif 4414 } else { 4415 bytes = len; 4416 offset = addr & (PAGE_SIZE-1); 4417 if (bytes > PAGE_SIZE-offset) 4418 bytes = PAGE_SIZE-offset; 4419 4420 maddr = kmap(page); 4421 if (write) { 4422 copy_to_user_page(vma, page, addr, 4423 maddr + offset, buf, bytes); 4424 set_page_dirty_lock(page); 4425 } else { 4426 copy_from_user_page(vma, page, addr, 4427 buf, maddr + offset, bytes); 4428 } 4429 kunmap(page); 4430 put_page(page); 4431 } 4432 len -= bytes; 4433 buf += bytes; 4434 addr += bytes; 4435 } 4436 up_read(&mm->mmap_sem); 4437 4438 return buf - old_buf; 4439 } 4440 4441 /** 4442 * access_remote_vm - access another process' address space 4443 * @mm: the mm_struct of the target address space 4444 * @addr: start address to access 4445 * @buf: source or destination buffer 4446 * @len: number of bytes to transfer 4447 * @gup_flags: flags modifying lookup behaviour 4448 * 4449 * The caller must hold a reference on @mm. 4450 */ 4451 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 4452 void *buf, int len, unsigned int gup_flags) 4453 { 4454 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags); 4455 } 4456 4457 /* 4458 * Access another process' address space. 4459 * Source/target buffer must be kernel space, 4460 * Do not walk the page table directly, use get_user_pages 4461 */ 4462 int access_process_vm(struct task_struct *tsk, unsigned long addr, 4463 void *buf, int len, unsigned int gup_flags) 4464 { 4465 struct mm_struct *mm; 4466 int ret; 4467 4468 mm = get_task_mm(tsk); 4469 if (!mm) 4470 return 0; 4471 4472 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags); 4473 4474 mmput(mm); 4475 4476 return ret; 4477 } 4478 EXPORT_SYMBOL_GPL(access_process_vm); 4479 4480 /* 4481 * Print the name of a VMA. 4482 */ 4483 void print_vma_addr(char *prefix, unsigned long ip) 4484 { 4485 struct mm_struct *mm = current->mm; 4486 struct vm_area_struct *vma; 4487 4488 /* 4489 * we might be running from an atomic context so we cannot sleep 4490 */ 4491 if (!down_read_trylock(&mm->mmap_sem)) 4492 return; 4493 4494 vma = find_vma(mm, ip); 4495 if (vma && vma->vm_file) { 4496 struct file *f = vma->vm_file; 4497 char *buf = (char *)__get_free_page(GFP_NOWAIT); 4498 if (buf) { 4499 char *p; 4500 4501 p = file_path(f, buf, PAGE_SIZE); 4502 if (IS_ERR(p)) 4503 p = "?"; 4504 printk("%s%s[%lx+%lx]", prefix, kbasename(p), 4505 vma->vm_start, 4506 vma->vm_end - vma->vm_start); 4507 free_page((unsigned long)buf); 4508 } 4509 } 4510 up_read(&mm->mmap_sem); 4511 } 4512 4513 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) 4514 void __might_fault(const char *file, int line) 4515 { 4516 /* 4517 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 4518 * holding the mmap_sem, this is safe because kernel memory doesn't 4519 * get paged out, therefore we'll never actually fault, and the 4520 * below annotations will generate false positives. 4521 */ 4522 if (uaccess_kernel()) 4523 return; 4524 if (pagefault_disabled()) 4525 return; 4526 __might_sleep(file, line, 0); 4527 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP) 4528 if (current->mm) 4529 might_lock_read(¤t->mm->mmap_sem); 4530 #endif 4531 } 4532 EXPORT_SYMBOL(__might_fault); 4533 #endif 4534 4535 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 4536 static void clear_gigantic_page(struct page *page, 4537 unsigned long addr, 4538 unsigned int pages_per_huge_page) 4539 { 4540 int i; 4541 struct page *p = page; 4542 4543 might_sleep(); 4544 for (i = 0; i < pages_per_huge_page; 4545 i++, p = mem_map_next(p, page, i)) { 4546 cond_resched(); 4547 clear_user_highpage(p, addr + i * PAGE_SIZE); 4548 } 4549 } 4550 void clear_huge_page(struct page *page, 4551 unsigned long addr_hint, unsigned int pages_per_huge_page) 4552 { 4553 int i, n, base, l; 4554 unsigned long addr = addr_hint & 4555 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1); 4556 4557 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4558 clear_gigantic_page(page, addr, pages_per_huge_page); 4559 return; 4560 } 4561 4562 /* Clear sub-page to access last to keep its cache lines hot */ 4563 might_sleep(); 4564 n = (addr_hint - addr) / PAGE_SIZE; 4565 if (2 * n <= pages_per_huge_page) { 4566 /* If sub-page to access in first half of huge page */ 4567 base = 0; 4568 l = n; 4569 /* Clear sub-pages at the end of huge page */ 4570 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) { 4571 cond_resched(); 4572 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 4573 } 4574 } else { 4575 /* If sub-page to access in second half of huge page */ 4576 base = pages_per_huge_page - 2 * (pages_per_huge_page - n); 4577 l = pages_per_huge_page - n; 4578 /* Clear sub-pages at the begin of huge page */ 4579 for (i = 0; i < base; i++) { 4580 cond_resched(); 4581 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 4582 } 4583 } 4584 /* 4585 * Clear remaining sub-pages in left-right-left-right pattern 4586 * towards the sub-page to access 4587 */ 4588 for (i = 0; i < l; i++) { 4589 int left_idx = base + i; 4590 int right_idx = base + 2 * l - 1 - i; 4591 4592 cond_resched(); 4593 clear_user_highpage(page + left_idx, 4594 addr + left_idx * PAGE_SIZE); 4595 cond_resched(); 4596 clear_user_highpage(page + right_idx, 4597 addr + right_idx * PAGE_SIZE); 4598 } 4599 } 4600 4601 static void copy_user_gigantic_page(struct page *dst, struct page *src, 4602 unsigned long addr, 4603 struct vm_area_struct *vma, 4604 unsigned int pages_per_huge_page) 4605 { 4606 int i; 4607 struct page *dst_base = dst; 4608 struct page *src_base = src; 4609 4610 for (i = 0; i < pages_per_huge_page; ) { 4611 cond_resched(); 4612 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 4613 4614 i++; 4615 dst = mem_map_next(dst, dst_base, i); 4616 src = mem_map_next(src, src_base, i); 4617 } 4618 } 4619 4620 void copy_user_huge_page(struct page *dst, struct page *src, 4621 unsigned long addr, struct vm_area_struct *vma, 4622 unsigned int pages_per_huge_page) 4623 { 4624 int i; 4625 4626 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4627 copy_user_gigantic_page(dst, src, addr, vma, 4628 pages_per_huge_page); 4629 return; 4630 } 4631 4632 might_sleep(); 4633 for (i = 0; i < pages_per_huge_page; i++) { 4634 cond_resched(); 4635 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 4636 } 4637 } 4638 4639 long copy_huge_page_from_user(struct page *dst_page, 4640 const void __user *usr_src, 4641 unsigned int pages_per_huge_page, 4642 bool allow_pagefault) 4643 { 4644 void *src = (void *)usr_src; 4645 void *page_kaddr; 4646 unsigned long i, rc = 0; 4647 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE; 4648 4649 for (i = 0; i < pages_per_huge_page; i++) { 4650 if (allow_pagefault) 4651 page_kaddr = kmap(dst_page + i); 4652 else 4653 page_kaddr = kmap_atomic(dst_page + i); 4654 rc = copy_from_user(page_kaddr, 4655 (const void __user *)(src + i * PAGE_SIZE), 4656 PAGE_SIZE); 4657 if (allow_pagefault) 4658 kunmap(dst_page + i); 4659 else 4660 kunmap_atomic(page_kaddr); 4661 4662 ret_val -= (PAGE_SIZE - rc); 4663 if (rc) 4664 break; 4665 4666 cond_resched(); 4667 } 4668 return ret_val; 4669 } 4670 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 4671 4672 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS 4673 4674 static struct kmem_cache *page_ptl_cachep; 4675 4676 void __init ptlock_cache_init(void) 4677 { 4678 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, 4679 SLAB_PANIC, NULL); 4680 } 4681 4682 bool ptlock_alloc(struct page *page) 4683 { 4684 spinlock_t *ptl; 4685 4686 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); 4687 if (!ptl) 4688 return false; 4689 page->ptl = ptl; 4690 return true; 4691 } 4692 4693 void ptlock_free(struct page *page) 4694 { 4695 kmem_cache_free(page_ptl_cachep, page->ptl); 4696 } 4697 #endif 4698