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/hugetlb.h> 44 #include <linux/mman.h> 45 #include <linux/swap.h> 46 #include <linux/highmem.h> 47 #include <linux/pagemap.h> 48 #include <linux/ksm.h> 49 #include <linux/rmap.h> 50 #include <linux/export.h> 51 #include <linux/delayacct.h> 52 #include <linux/init.h> 53 #include <linux/writeback.h> 54 #include <linux/memcontrol.h> 55 #include <linux/mmu_notifier.h> 56 #include <linux/kallsyms.h> 57 #include <linux/swapops.h> 58 #include <linux/elf.h> 59 #include <linux/gfp.h> 60 #include <linux/migrate.h> 61 #include <linux/string.h> 62 #include <linux/dma-debug.h> 63 #include <linux/debugfs.h> 64 65 #include <asm/io.h> 66 #include <asm/pgalloc.h> 67 #include <asm/uaccess.h> 68 #include <asm/tlb.h> 69 #include <asm/tlbflush.h> 70 #include <asm/pgtable.h> 71 72 #include "internal.h" 73 74 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS 75 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. 76 #endif 77 78 #ifndef CONFIG_NEED_MULTIPLE_NODES 79 /* use the per-pgdat data instead for discontigmem - mbligh */ 80 unsigned long max_mapnr; 81 struct page *mem_map; 82 83 EXPORT_SYMBOL(max_mapnr); 84 EXPORT_SYMBOL(mem_map); 85 #endif 86 87 /* 88 * A number of key systems in x86 including ioremap() rely on the assumption 89 * that high_memory defines the upper bound on direct map memory, then end 90 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 91 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 92 * and ZONE_HIGHMEM. 93 */ 94 void * high_memory; 95 96 EXPORT_SYMBOL(high_memory); 97 98 /* 99 * Randomize the address space (stacks, mmaps, brk, etc.). 100 * 101 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 102 * as ancient (libc5 based) binaries can segfault. ) 103 */ 104 int randomize_va_space __read_mostly = 105 #ifdef CONFIG_COMPAT_BRK 106 1; 107 #else 108 2; 109 #endif 110 111 static int __init disable_randmaps(char *s) 112 { 113 randomize_va_space = 0; 114 return 1; 115 } 116 __setup("norandmaps", disable_randmaps); 117 118 unsigned long zero_pfn __read_mostly; 119 unsigned long highest_memmap_pfn __read_mostly; 120 121 /* 122 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 123 */ 124 static int __init init_zero_pfn(void) 125 { 126 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 127 return 0; 128 } 129 core_initcall(init_zero_pfn); 130 131 132 #if defined(SPLIT_RSS_COUNTING) 133 134 void sync_mm_rss(struct mm_struct *mm) 135 { 136 int i; 137 138 for (i = 0; i < NR_MM_COUNTERS; i++) { 139 if (current->rss_stat.count[i]) { 140 add_mm_counter(mm, i, current->rss_stat.count[i]); 141 current->rss_stat.count[i] = 0; 142 } 143 } 144 current->rss_stat.events = 0; 145 } 146 147 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 148 { 149 struct task_struct *task = current; 150 151 if (likely(task->mm == mm)) 152 task->rss_stat.count[member] += val; 153 else 154 add_mm_counter(mm, member, val); 155 } 156 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 157 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 158 159 /* sync counter once per 64 page faults */ 160 #define TASK_RSS_EVENTS_THRESH (64) 161 static void check_sync_rss_stat(struct task_struct *task) 162 { 163 if (unlikely(task != current)) 164 return; 165 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 166 sync_mm_rss(task->mm); 167 } 168 #else /* SPLIT_RSS_COUNTING */ 169 170 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 171 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 172 173 static void check_sync_rss_stat(struct task_struct *task) 174 { 175 } 176 177 #endif /* SPLIT_RSS_COUNTING */ 178 179 #ifdef HAVE_GENERIC_MMU_GATHER 180 181 static int tlb_next_batch(struct mmu_gather *tlb) 182 { 183 struct mmu_gather_batch *batch; 184 185 batch = tlb->active; 186 if (batch->next) { 187 tlb->active = batch->next; 188 return 1; 189 } 190 191 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) 192 return 0; 193 194 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 195 if (!batch) 196 return 0; 197 198 tlb->batch_count++; 199 batch->next = NULL; 200 batch->nr = 0; 201 batch->max = MAX_GATHER_BATCH; 202 203 tlb->active->next = batch; 204 tlb->active = batch; 205 206 return 1; 207 } 208 209 /* tlb_gather_mmu 210 * Called to initialize an (on-stack) mmu_gather structure for page-table 211 * tear-down from @mm. The @fullmm argument is used when @mm is without 212 * users and we're going to destroy the full address space (exit/execve). 213 */ 214 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end) 215 { 216 tlb->mm = mm; 217 218 /* Is it from 0 to ~0? */ 219 tlb->fullmm = !(start | (end+1)); 220 tlb->need_flush_all = 0; 221 tlb->start = start; 222 tlb->end = end; 223 tlb->need_flush = 0; 224 tlb->local.next = NULL; 225 tlb->local.nr = 0; 226 tlb->local.max = ARRAY_SIZE(tlb->__pages); 227 tlb->active = &tlb->local; 228 tlb->batch_count = 0; 229 230 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 231 tlb->batch = NULL; 232 #endif 233 } 234 235 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) 236 { 237 tlb->need_flush = 0; 238 tlb_flush(tlb); 239 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 240 tlb_table_flush(tlb); 241 #endif 242 } 243 244 static void tlb_flush_mmu_free(struct mmu_gather *tlb) 245 { 246 struct mmu_gather_batch *batch; 247 248 for (batch = &tlb->local; batch; batch = batch->next) { 249 free_pages_and_swap_cache(batch->pages, batch->nr); 250 batch->nr = 0; 251 } 252 tlb->active = &tlb->local; 253 } 254 255 void tlb_flush_mmu(struct mmu_gather *tlb) 256 { 257 if (!tlb->need_flush) 258 return; 259 tlb_flush_mmu_tlbonly(tlb); 260 tlb_flush_mmu_free(tlb); 261 } 262 263 /* tlb_finish_mmu 264 * Called at the end of the shootdown operation to free up any resources 265 * that were required. 266 */ 267 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 268 { 269 struct mmu_gather_batch *batch, *next; 270 271 tlb_flush_mmu(tlb); 272 273 /* keep the page table cache within bounds */ 274 check_pgt_cache(); 275 276 for (batch = tlb->local.next; batch; batch = next) { 277 next = batch->next; 278 free_pages((unsigned long)batch, 0); 279 } 280 tlb->local.next = NULL; 281 } 282 283 /* __tlb_remove_page 284 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 285 * handling the additional races in SMP caused by other CPUs caching valid 286 * mappings in their TLBs. Returns the number of free page slots left. 287 * When out of page slots we must call tlb_flush_mmu(). 288 */ 289 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) 290 { 291 struct mmu_gather_batch *batch; 292 293 VM_BUG_ON(!tlb->need_flush); 294 295 batch = tlb->active; 296 batch->pages[batch->nr++] = page; 297 if (batch->nr == batch->max) { 298 if (!tlb_next_batch(tlb)) 299 return 0; 300 batch = tlb->active; 301 } 302 VM_BUG_ON_PAGE(batch->nr > batch->max, page); 303 304 return batch->max - batch->nr; 305 } 306 307 #endif /* HAVE_GENERIC_MMU_GATHER */ 308 309 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 310 311 /* 312 * See the comment near struct mmu_table_batch. 313 */ 314 315 static void tlb_remove_table_smp_sync(void *arg) 316 { 317 /* Simply deliver the interrupt */ 318 } 319 320 static void tlb_remove_table_one(void *table) 321 { 322 /* 323 * This isn't an RCU grace period and hence the page-tables cannot be 324 * assumed to be actually RCU-freed. 325 * 326 * It is however sufficient for software page-table walkers that rely on 327 * IRQ disabling. See the comment near struct mmu_table_batch. 328 */ 329 smp_call_function(tlb_remove_table_smp_sync, NULL, 1); 330 __tlb_remove_table(table); 331 } 332 333 static void tlb_remove_table_rcu(struct rcu_head *head) 334 { 335 struct mmu_table_batch *batch; 336 int i; 337 338 batch = container_of(head, struct mmu_table_batch, rcu); 339 340 for (i = 0; i < batch->nr; i++) 341 __tlb_remove_table(batch->tables[i]); 342 343 free_page((unsigned long)batch); 344 } 345 346 void tlb_table_flush(struct mmu_gather *tlb) 347 { 348 struct mmu_table_batch **batch = &tlb->batch; 349 350 if (*batch) { 351 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); 352 *batch = NULL; 353 } 354 } 355 356 void tlb_remove_table(struct mmu_gather *tlb, void *table) 357 { 358 struct mmu_table_batch **batch = &tlb->batch; 359 360 tlb->need_flush = 1; 361 362 /* 363 * When there's less then two users of this mm there cannot be a 364 * concurrent page-table walk. 365 */ 366 if (atomic_read(&tlb->mm->mm_users) < 2) { 367 __tlb_remove_table(table); 368 return; 369 } 370 371 if (*batch == NULL) { 372 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); 373 if (*batch == NULL) { 374 tlb_remove_table_one(table); 375 return; 376 } 377 (*batch)->nr = 0; 378 } 379 (*batch)->tables[(*batch)->nr++] = table; 380 if ((*batch)->nr == MAX_TABLE_BATCH) 381 tlb_table_flush(tlb); 382 } 383 384 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ 385 386 /* 387 * Note: this doesn't free the actual pages themselves. That 388 * has been handled earlier when unmapping all the memory regions. 389 */ 390 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 391 unsigned long addr) 392 { 393 pgtable_t token = pmd_pgtable(*pmd); 394 pmd_clear(pmd); 395 pte_free_tlb(tlb, token, addr); 396 atomic_long_dec(&tlb->mm->nr_ptes); 397 } 398 399 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 400 unsigned long addr, unsigned long end, 401 unsigned long floor, unsigned long ceiling) 402 { 403 pmd_t *pmd; 404 unsigned long next; 405 unsigned long start; 406 407 start = addr; 408 pmd = pmd_offset(pud, addr); 409 do { 410 next = pmd_addr_end(addr, end); 411 if (pmd_none_or_clear_bad(pmd)) 412 continue; 413 free_pte_range(tlb, pmd, addr); 414 } while (pmd++, addr = next, addr != end); 415 416 start &= PUD_MASK; 417 if (start < floor) 418 return; 419 if (ceiling) { 420 ceiling &= PUD_MASK; 421 if (!ceiling) 422 return; 423 } 424 if (end - 1 > ceiling - 1) 425 return; 426 427 pmd = pmd_offset(pud, start); 428 pud_clear(pud); 429 pmd_free_tlb(tlb, pmd, start); 430 } 431 432 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 433 unsigned long addr, unsigned long end, 434 unsigned long floor, unsigned long ceiling) 435 { 436 pud_t *pud; 437 unsigned long next; 438 unsigned long start; 439 440 start = addr; 441 pud = pud_offset(pgd, addr); 442 do { 443 next = pud_addr_end(addr, end); 444 if (pud_none_or_clear_bad(pud)) 445 continue; 446 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 447 } while (pud++, addr = next, addr != end); 448 449 start &= PGDIR_MASK; 450 if (start < floor) 451 return; 452 if (ceiling) { 453 ceiling &= PGDIR_MASK; 454 if (!ceiling) 455 return; 456 } 457 if (end - 1 > ceiling - 1) 458 return; 459 460 pud = pud_offset(pgd, start); 461 pgd_clear(pgd); 462 pud_free_tlb(tlb, pud, start); 463 } 464 465 /* 466 * This function frees user-level page tables of a process. 467 */ 468 void free_pgd_range(struct mmu_gather *tlb, 469 unsigned long addr, unsigned long end, 470 unsigned long floor, unsigned long ceiling) 471 { 472 pgd_t *pgd; 473 unsigned long next; 474 475 /* 476 * The next few lines have given us lots of grief... 477 * 478 * Why are we testing PMD* at this top level? Because often 479 * there will be no work to do at all, and we'd prefer not to 480 * go all the way down to the bottom just to discover that. 481 * 482 * Why all these "- 1"s? Because 0 represents both the bottom 483 * of the address space and the top of it (using -1 for the 484 * top wouldn't help much: the masks would do the wrong thing). 485 * The rule is that addr 0 and floor 0 refer to the bottom of 486 * the address space, but end 0 and ceiling 0 refer to the top 487 * Comparisons need to use "end - 1" and "ceiling - 1" (though 488 * that end 0 case should be mythical). 489 * 490 * Wherever addr is brought up or ceiling brought down, we must 491 * be careful to reject "the opposite 0" before it confuses the 492 * subsequent tests. But what about where end is brought down 493 * by PMD_SIZE below? no, end can't go down to 0 there. 494 * 495 * Whereas we round start (addr) and ceiling down, by different 496 * masks at different levels, in order to test whether a table 497 * now has no other vmas using it, so can be freed, we don't 498 * bother to round floor or end up - the tests don't need that. 499 */ 500 501 addr &= PMD_MASK; 502 if (addr < floor) { 503 addr += PMD_SIZE; 504 if (!addr) 505 return; 506 } 507 if (ceiling) { 508 ceiling &= PMD_MASK; 509 if (!ceiling) 510 return; 511 } 512 if (end - 1 > ceiling - 1) 513 end -= PMD_SIZE; 514 if (addr > end - 1) 515 return; 516 517 pgd = pgd_offset(tlb->mm, addr); 518 do { 519 next = pgd_addr_end(addr, end); 520 if (pgd_none_or_clear_bad(pgd)) 521 continue; 522 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 523 } while (pgd++, addr = next, addr != end); 524 } 525 526 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 527 unsigned long floor, unsigned long ceiling) 528 { 529 while (vma) { 530 struct vm_area_struct *next = vma->vm_next; 531 unsigned long addr = vma->vm_start; 532 533 /* 534 * Hide vma from rmap and truncate_pagecache before freeing 535 * pgtables 536 */ 537 unlink_anon_vmas(vma); 538 unlink_file_vma(vma); 539 540 if (is_vm_hugetlb_page(vma)) { 541 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 542 floor, next? next->vm_start: ceiling); 543 } else { 544 /* 545 * Optimization: gather nearby vmas into one call down 546 */ 547 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 548 && !is_vm_hugetlb_page(next)) { 549 vma = next; 550 next = vma->vm_next; 551 unlink_anon_vmas(vma); 552 unlink_file_vma(vma); 553 } 554 free_pgd_range(tlb, addr, vma->vm_end, 555 floor, next? next->vm_start: ceiling); 556 } 557 vma = next; 558 } 559 } 560 561 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, 562 pmd_t *pmd, unsigned long address) 563 { 564 spinlock_t *ptl; 565 pgtable_t new = pte_alloc_one(mm, address); 566 int wait_split_huge_page; 567 if (!new) 568 return -ENOMEM; 569 570 /* 571 * Ensure all pte setup (eg. pte page lock and page clearing) are 572 * visible before the pte is made visible to other CPUs by being 573 * put into page tables. 574 * 575 * The other side of the story is the pointer chasing in the page 576 * table walking code (when walking the page table without locking; 577 * ie. most of the time). Fortunately, these data accesses consist 578 * of a chain of data-dependent loads, meaning most CPUs (alpha 579 * being the notable exception) will already guarantee loads are 580 * seen in-order. See the alpha page table accessors for the 581 * smp_read_barrier_depends() barriers in page table walking code. 582 */ 583 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 584 585 ptl = pmd_lock(mm, pmd); 586 wait_split_huge_page = 0; 587 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 588 atomic_long_inc(&mm->nr_ptes); 589 pmd_populate(mm, pmd, new); 590 new = NULL; 591 } else if (unlikely(pmd_trans_splitting(*pmd))) 592 wait_split_huge_page = 1; 593 spin_unlock(ptl); 594 if (new) 595 pte_free(mm, new); 596 if (wait_split_huge_page) 597 wait_split_huge_page(vma->anon_vma, pmd); 598 return 0; 599 } 600 601 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 602 { 603 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 604 if (!new) 605 return -ENOMEM; 606 607 smp_wmb(); /* See comment in __pte_alloc */ 608 609 spin_lock(&init_mm.page_table_lock); 610 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 611 pmd_populate_kernel(&init_mm, pmd, new); 612 new = NULL; 613 } else 614 VM_BUG_ON(pmd_trans_splitting(*pmd)); 615 spin_unlock(&init_mm.page_table_lock); 616 if (new) 617 pte_free_kernel(&init_mm, new); 618 return 0; 619 } 620 621 static inline void init_rss_vec(int *rss) 622 { 623 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 624 } 625 626 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 627 { 628 int i; 629 630 if (current->mm == mm) 631 sync_mm_rss(mm); 632 for (i = 0; i < NR_MM_COUNTERS; i++) 633 if (rss[i]) 634 add_mm_counter(mm, i, rss[i]); 635 } 636 637 /* 638 * This function is called to print an error when a bad pte 639 * is found. For example, we might have a PFN-mapped pte in 640 * a region that doesn't allow it. 641 * 642 * The calling function must still handle the error. 643 */ 644 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 645 pte_t pte, struct page *page) 646 { 647 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 648 pud_t *pud = pud_offset(pgd, addr); 649 pmd_t *pmd = pmd_offset(pud, addr); 650 struct address_space *mapping; 651 pgoff_t index; 652 static unsigned long resume; 653 static unsigned long nr_shown; 654 static unsigned long nr_unshown; 655 656 /* 657 * Allow a burst of 60 reports, then keep quiet for that minute; 658 * or allow a steady drip of one report per second. 659 */ 660 if (nr_shown == 60) { 661 if (time_before(jiffies, resume)) { 662 nr_unshown++; 663 return; 664 } 665 if (nr_unshown) { 666 printk(KERN_ALERT 667 "BUG: Bad page map: %lu messages suppressed\n", 668 nr_unshown); 669 nr_unshown = 0; 670 } 671 nr_shown = 0; 672 } 673 if (nr_shown++ == 0) 674 resume = jiffies + 60 * HZ; 675 676 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 677 index = linear_page_index(vma, addr); 678 679 printk(KERN_ALERT 680 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 681 current->comm, 682 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 683 if (page) 684 dump_page(page, "bad pte"); 685 printk(KERN_ALERT 686 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 687 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 688 /* 689 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 690 */ 691 if (vma->vm_ops) 692 printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n", 693 vma->vm_ops->fault); 694 if (vma->vm_file) 695 printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n", 696 vma->vm_file->f_op->mmap); 697 dump_stack(); 698 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); 699 } 700 701 static inline bool is_cow_mapping(vm_flags_t flags) 702 { 703 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 704 } 705 706 /* 707 * vm_normal_page -- This function gets the "struct page" associated with a pte. 708 * 709 * "Special" mappings do not wish to be associated with a "struct page" (either 710 * it doesn't exist, or it exists but they don't want to touch it). In this 711 * case, NULL is returned here. "Normal" mappings do have a struct page. 712 * 713 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 714 * pte bit, in which case this function is trivial. Secondly, an architecture 715 * may not have a spare pte bit, which requires a more complicated scheme, 716 * described below. 717 * 718 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 719 * special mapping (even if there are underlying and valid "struct pages"). 720 * COWed pages of a VM_PFNMAP are always normal. 721 * 722 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 723 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 724 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 725 * mapping will always honor the rule 726 * 727 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 728 * 729 * And for normal mappings this is false. 730 * 731 * This restricts such mappings to be a linear translation from virtual address 732 * to pfn. To get around this restriction, we allow arbitrary mappings so long 733 * as the vma is not a COW mapping; in that case, we know that all ptes are 734 * special (because none can have been COWed). 735 * 736 * 737 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 738 * 739 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 740 * page" backing, however the difference is that _all_ pages with a struct 741 * page (that is, those where pfn_valid is true) are refcounted and considered 742 * normal pages by the VM. The disadvantage is that pages are refcounted 743 * (which can be slower and simply not an option for some PFNMAP users). The 744 * advantage is that we don't have to follow the strict linearity rule of 745 * PFNMAP mappings in order to support COWable mappings. 746 * 747 */ 748 #ifdef __HAVE_ARCH_PTE_SPECIAL 749 # define HAVE_PTE_SPECIAL 1 750 #else 751 # define HAVE_PTE_SPECIAL 0 752 #endif 753 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 754 pte_t pte) 755 { 756 unsigned long pfn = pte_pfn(pte); 757 758 if (HAVE_PTE_SPECIAL) { 759 if (likely(!pte_special(pte))) 760 goto check_pfn; 761 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 762 return NULL; 763 if (!is_zero_pfn(pfn)) 764 print_bad_pte(vma, addr, pte, NULL); 765 return NULL; 766 } 767 768 /* !HAVE_PTE_SPECIAL case follows: */ 769 770 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 771 if (vma->vm_flags & VM_MIXEDMAP) { 772 if (!pfn_valid(pfn)) 773 return NULL; 774 goto out; 775 } else { 776 unsigned long off; 777 off = (addr - vma->vm_start) >> PAGE_SHIFT; 778 if (pfn == vma->vm_pgoff + off) 779 return NULL; 780 if (!is_cow_mapping(vma->vm_flags)) 781 return NULL; 782 } 783 } 784 785 if (is_zero_pfn(pfn)) 786 return NULL; 787 check_pfn: 788 if (unlikely(pfn > highest_memmap_pfn)) { 789 print_bad_pte(vma, addr, pte, NULL); 790 return NULL; 791 } 792 793 /* 794 * NOTE! We still have PageReserved() pages in the page tables. 795 * eg. VDSO mappings can cause them to exist. 796 */ 797 out: 798 return pfn_to_page(pfn); 799 } 800 801 /* 802 * copy one vm_area from one task to the other. Assumes the page tables 803 * already present in the new task to be cleared in the whole range 804 * covered by this vma. 805 */ 806 807 static inline unsigned long 808 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 809 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 810 unsigned long addr, int *rss) 811 { 812 unsigned long vm_flags = vma->vm_flags; 813 pte_t pte = *src_pte; 814 struct page *page; 815 816 /* pte contains position in swap or file, so copy. */ 817 if (unlikely(!pte_present(pte))) { 818 if (!pte_file(pte)) { 819 swp_entry_t entry = pte_to_swp_entry(pte); 820 821 if (swap_duplicate(entry) < 0) 822 return entry.val; 823 824 /* make sure dst_mm is on swapoff's mmlist. */ 825 if (unlikely(list_empty(&dst_mm->mmlist))) { 826 spin_lock(&mmlist_lock); 827 if (list_empty(&dst_mm->mmlist)) 828 list_add(&dst_mm->mmlist, 829 &src_mm->mmlist); 830 spin_unlock(&mmlist_lock); 831 } 832 if (likely(!non_swap_entry(entry))) 833 rss[MM_SWAPENTS]++; 834 else if (is_migration_entry(entry)) { 835 page = migration_entry_to_page(entry); 836 837 if (PageAnon(page)) 838 rss[MM_ANONPAGES]++; 839 else 840 rss[MM_FILEPAGES]++; 841 842 if (is_write_migration_entry(entry) && 843 is_cow_mapping(vm_flags)) { 844 /* 845 * COW mappings require pages in both 846 * parent and child to be set to read. 847 */ 848 make_migration_entry_read(&entry); 849 pte = swp_entry_to_pte(entry); 850 if (pte_swp_soft_dirty(*src_pte)) 851 pte = pte_swp_mksoft_dirty(pte); 852 set_pte_at(src_mm, addr, src_pte, pte); 853 } 854 } 855 } 856 goto out_set_pte; 857 } 858 859 /* 860 * If it's a COW mapping, write protect it both 861 * in the parent and the child 862 */ 863 if (is_cow_mapping(vm_flags)) { 864 ptep_set_wrprotect(src_mm, addr, src_pte); 865 pte = pte_wrprotect(pte); 866 } 867 868 /* 869 * If it's a shared mapping, mark it clean in 870 * the child 871 */ 872 if (vm_flags & VM_SHARED) 873 pte = pte_mkclean(pte); 874 pte = pte_mkold(pte); 875 876 page = vm_normal_page(vma, addr, pte); 877 if (page) { 878 get_page(page); 879 page_dup_rmap(page); 880 if (PageAnon(page)) 881 rss[MM_ANONPAGES]++; 882 else 883 rss[MM_FILEPAGES]++; 884 } 885 886 out_set_pte: 887 set_pte_at(dst_mm, addr, dst_pte, pte); 888 return 0; 889 } 890 891 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 892 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 893 unsigned long addr, unsigned long end) 894 { 895 pte_t *orig_src_pte, *orig_dst_pte; 896 pte_t *src_pte, *dst_pte; 897 spinlock_t *src_ptl, *dst_ptl; 898 int progress = 0; 899 int rss[NR_MM_COUNTERS]; 900 swp_entry_t entry = (swp_entry_t){0}; 901 902 again: 903 init_rss_vec(rss); 904 905 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 906 if (!dst_pte) 907 return -ENOMEM; 908 src_pte = pte_offset_map(src_pmd, addr); 909 src_ptl = pte_lockptr(src_mm, src_pmd); 910 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 911 orig_src_pte = src_pte; 912 orig_dst_pte = dst_pte; 913 arch_enter_lazy_mmu_mode(); 914 915 do { 916 /* 917 * We are holding two locks at this point - either of them 918 * could generate latencies in another task on another CPU. 919 */ 920 if (progress >= 32) { 921 progress = 0; 922 if (need_resched() || 923 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 924 break; 925 } 926 if (pte_none(*src_pte)) { 927 progress++; 928 continue; 929 } 930 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 931 vma, addr, rss); 932 if (entry.val) 933 break; 934 progress += 8; 935 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 936 937 arch_leave_lazy_mmu_mode(); 938 spin_unlock(src_ptl); 939 pte_unmap(orig_src_pte); 940 add_mm_rss_vec(dst_mm, rss); 941 pte_unmap_unlock(orig_dst_pte, dst_ptl); 942 cond_resched(); 943 944 if (entry.val) { 945 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 946 return -ENOMEM; 947 progress = 0; 948 } 949 if (addr != end) 950 goto again; 951 return 0; 952 } 953 954 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 955 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 956 unsigned long addr, unsigned long end) 957 { 958 pmd_t *src_pmd, *dst_pmd; 959 unsigned long next; 960 961 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 962 if (!dst_pmd) 963 return -ENOMEM; 964 src_pmd = pmd_offset(src_pud, addr); 965 do { 966 next = pmd_addr_end(addr, end); 967 if (pmd_trans_huge(*src_pmd)) { 968 int err; 969 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); 970 err = copy_huge_pmd(dst_mm, src_mm, 971 dst_pmd, src_pmd, addr, vma); 972 if (err == -ENOMEM) 973 return -ENOMEM; 974 if (!err) 975 continue; 976 /* fall through */ 977 } 978 if (pmd_none_or_clear_bad(src_pmd)) 979 continue; 980 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 981 vma, addr, next)) 982 return -ENOMEM; 983 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 984 return 0; 985 } 986 987 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 988 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 989 unsigned long addr, unsigned long end) 990 { 991 pud_t *src_pud, *dst_pud; 992 unsigned long next; 993 994 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 995 if (!dst_pud) 996 return -ENOMEM; 997 src_pud = pud_offset(src_pgd, addr); 998 do { 999 next = pud_addr_end(addr, end); 1000 if (pud_none_or_clear_bad(src_pud)) 1001 continue; 1002 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 1003 vma, addr, next)) 1004 return -ENOMEM; 1005 } while (dst_pud++, src_pud++, addr = next, addr != end); 1006 return 0; 1007 } 1008 1009 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1010 struct vm_area_struct *vma) 1011 { 1012 pgd_t *src_pgd, *dst_pgd; 1013 unsigned long next; 1014 unsigned long addr = vma->vm_start; 1015 unsigned long end = vma->vm_end; 1016 unsigned long mmun_start; /* For mmu_notifiers */ 1017 unsigned long mmun_end; /* For mmu_notifiers */ 1018 bool is_cow; 1019 int ret; 1020 1021 /* 1022 * Don't copy ptes where a page fault will fill them correctly. 1023 * Fork becomes much lighter when there are big shared or private 1024 * readonly mappings. The tradeoff is that copy_page_range is more 1025 * efficient than faulting. 1026 */ 1027 if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR | 1028 VM_PFNMAP | VM_MIXEDMAP))) { 1029 if (!vma->anon_vma) 1030 return 0; 1031 } 1032 1033 if (is_vm_hugetlb_page(vma)) 1034 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 1035 1036 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 1037 /* 1038 * We do not free on error cases below as remove_vma 1039 * gets called on error from higher level routine 1040 */ 1041 ret = track_pfn_copy(vma); 1042 if (ret) 1043 return ret; 1044 } 1045 1046 /* 1047 * We need to invalidate the secondary MMU mappings only when 1048 * there could be a permission downgrade on the ptes of the 1049 * parent mm. And a permission downgrade will only happen if 1050 * is_cow_mapping() returns true. 1051 */ 1052 is_cow = is_cow_mapping(vma->vm_flags); 1053 mmun_start = addr; 1054 mmun_end = end; 1055 if (is_cow) 1056 mmu_notifier_invalidate_range_start(src_mm, mmun_start, 1057 mmun_end); 1058 1059 ret = 0; 1060 dst_pgd = pgd_offset(dst_mm, addr); 1061 src_pgd = pgd_offset(src_mm, addr); 1062 do { 1063 next = pgd_addr_end(addr, end); 1064 if (pgd_none_or_clear_bad(src_pgd)) 1065 continue; 1066 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 1067 vma, addr, next))) { 1068 ret = -ENOMEM; 1069 break; 1070 } 1071 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1072 1073 if (is_cow) 1074 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); 1075 return ret; 1076 } 1077 1078 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1079 struct vm_area_struct *vma, pmd_t *pmd, 1080 unsigned long addr, unsigned long end, 1081 struct zap_details *details) 1082 { 1083 struct mm_struct *mm = tlb->mm; 1084 int force_flush = 0; 1085 int rss[NR_MM_COUNTERS]; 1086 spinlock_t *ptl; 1087 pte_t *start_pte; 1088 pte_t *pte; 1089 1090 again: 1091 init_rss_vec(rss); 1092 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1093 pte = start_pte; 1094 arch_enter_lazy_mmu_mode(); 1095 do { 1096 pte_t ptent = *pte; 1097 if (pte_none(ptent)) { 1098 continue; 1099 } 1100 1101 if (pte_present(ptent)) { 1102 struct page *page; 1103 1104 page = vm_normal_page(vma, addr, ptent); 1105 if (unlikely(details) && page) { 1106 /* 1107 * unmap_shared_mapping_pages() wants to 1108 * invalidate cache without truncating: 1109 * unmap shared but keep private pages. 1110 */ 1111 if (details->check_mapping && 1112 details->check_mapping != page->mapping) 1113 continue; 1114 /* 1115 * Each page->index must be checked when 1116 * invalidating or truncating nonlinear. 1117 */ 1118 if (details->nonlinear_vma && 1119 (page->index < details->first_index || 1120 page->index > details->last_index)) 1121 continue; 1122 } 1123 ptent = ptep_get_and_clear_full(mm, addr, pte, 1124 tlb->fullmm); 1125 tlb_remove_tlb_entry(tlb, pte, addr); 1126 if (unlikely(!page)) 1127 continue; 1128 if (unlikely(details) && details->nonlinear_vma 1129 && linear_page_index(details->nonlinear_vma, 1130 addr) != page->index) { 1131 pte_t ptfile = pgoff_to_pte(page->index); 1132 if (pte_soft_dirty(ptent)) 1133 pte_file_mksoft_dirty(ptfile); 1134 set_pte_at(mm, addr, pte, ptfile); 1135 } 1136 if (PageAnon(page)) 1137 rss[MM_ANONPAGES]--; 1138 else { 1139 if (pte_dirty(ptent)) { 1140 force_flush = 1; 1141 set_page_dirty(page); 1142 } 1143 if (pte_young(ptent) && 1144 likely(!(vma->vm_flags & VM_SEQ_READ))) 1145 mark_page_accessed(page); 1146 rss[MM_FILEPAGES]--; 1147 } 1148 page_remove_rmap(page); 1149 if (unlikely(page_mapcount(page) < 0)) 1150 print_bad_pte(vma, addr, ptent, page); 1151 if (unlikely(!__tlb_remove_page(tlb, page))) { 1152 force_flush = 1; 1153 break; 1154 } 1155 continue; 1156 } 1157 /* 1158 * If details->check_mapping, we leave swap entries; 1159 * if details->nonlinear_vma, we leave file entries. 1160 */ 1161 if (unlikely(details)) 1162 continue; 1163 if (pte_file(ptent)) { 1164 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 1165 print_bad_pte(vma, addr, ptent, NULL); 1166 } else { 1167 swp_entry_t entry = pte_to_swp_entry(ptent); 1168 1169 if (!non_swap_entry(entry)) 1170 rss[MM_SWAPENTS]--; 1171 else if (is_migration_entry(entry)) { 1172 struct page *page; 1173 1174 page = migration_entry_to_page(entry); 1175 1176 if (PageAnon(page)) 1177 rss[MM_ANONPAGES]--; 1178 else 1179 rss[MM_FILEPAGES]--; 1180 } 1181 if (unlikely(!free_swap_and_cache(entry))) 1182 print_bad_pte(vma, addr, ptent, NULL); 1183 } 1184 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1185 } while (pte++, addr += PAGE_SIZE, addr != end); 1186 1187 add_mm_rss_vec(mm, rss); 1188 arch_leave_lazy_mmu_mode(); 1189 1190 /* Do the actual TLB flush before dropping ptl */ 1191 if (force_flush) { 1192 unsigned long old_end; 1193 1194 /* 1195 * Flush the TLB just for the previous segment, 1196 * then update the range to be the remaining 1197 * TLB range. 1198 */ 1199 old_end = tlb->end; 1200 tlb->end = addr; 1201 tlb_flush_mmu_tlbonly(tlb); 1202 tlb->start = addr; 1203 tlb->end = old_end; 1204 } 1205 pte_unmap_unlock(start_pte, ptl); 1206 1207 /* 1208 * If we forced a TLB flush (either due to running out of 1209 * batch buffers or because we needed to flush dirty TLB 1210 * entries before releasing the ptl), free the batched 1211 * memory too. Restart if we didn't do everything. 1212 */ 1213 if (force_flush) { 1214 force_flush = 0; 1215 tlb_flush_mmu_free(tlb); 1216 1217 if (addr != end) 1218 goto again; 1219 } 1220 1221 return addr; 1222 } 1223 1224 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1225 struct vm_area_struct *vma, pud_t *pud, 1226 unsigned long addr, unsigned long end, 1227 struct zap_details *details) 1228 { 1229 pmd_t *pmd; 1230 unsigned long next; 1231 1232 pmd = pmd_offset(pud, addr); 1233 do { 1234 next = pmd_addr_end(addr, end); 1235 if (pmd_trans_huge(*pmd)) { 1236 if (next - addr != HPAGE_PMD_SIZE) { 1237 #ifdef CONFIG_DEBUG_VM 1238 if (!rwsem_is_locked(&tlb->mm->mmap_sem)) { 1239 pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n", 1240 __func__, addr, end, 1241 vma->vm_start, 1242 vma->vm_end); 1243 BUG(); 1244 } 1245 #endif 1246 split_huge_page_pmd(vma, addr, pmd); 1247 } else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1248 goto next; 1249 /* fall through */ 1250 } 1251 /* 1252 * Here there can be other concurrent MADV_DONTNEED or 1253 * trans huge page faults running, and if the pmd is 1254 * none or trans huge it can change under us. This is 1255 * because MADV_DONTNEED holds the mmap_sem in read 1256 * mode. 1257 */ 1258 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1259 goto next; 1260 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1261 next: 1262 cond_resched(); 1263 } while (pmd++, addr = next, addr != end); 1264 1265 return addr; 1266 } 1267 1268 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1269 struct vm_area_struct *vma, pgd_t *pgd, 1270 unsigned long addr, unsigned long end, 1271 struct zap_details *details) 1272 { 1273 pud_t *pud; 1274 unsigned long next; 1275 1276 pud = pud_offset(pgd, addr); 1277 do { 1278 next = pud_addr_end(addr, end); 1279 if (pud_none_or_clear_bad(pud)) 1280 continue; 1281 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1282 } while (pud++, addr = next, addr != end); 1283 1284 return addr; 1285 } 1286 1287 static void unmap_page_range(struct mmu_gather *tlb, 1288 struct vm_area_struct *vma, 1289 unsigned long addr, unsigned long end, 1290 struct zap_details *details) 1291 { 1292 pgd_t *pgd; 1293 unsigned long next; 1294 1295 if (details && !details->check_mapping && !details->nonlinear_vma) 1296 details = NULL; 1297 1298 BUG_ON(addr >= end); 1299 mem_cgroup_uncharge_start(); 1300 tlb_start_vma(tlb, vma); 1301 pgd = pgd_offset(vma->vm_mm, addr); 1302 do { 1303 next = pgd_addr_end(addr, end); 1304 if (pgd_none_or_clear_bad(pgd)) 1305 continue; 1306 next = zap_pud_range(tlb, vma, pgd, addr, next, details); 1307 } while (pgd++, addr = next, addr != end); 1308 tlb_end_vma(tlb, vma); 1309 mem_cgroup_uncharge_end(); 1310 } 1311 1312 1313 static void unmap_single_vma(struct mmu_gather *tlb, 1314 struct vm_area_struct *vma, unsigned long start_addr, 1315 unsigned long end_addr, 1316 struct zap_details *details) 1317 { 1318 unsigned long start = max(vma->vm_start, start_addr); 1319 unsigned long end; 1320 1321 if (start >= vma->vm_end) 1322 return; 1323 end = min(vma->vm_end, end_addr); 1324 if (end <= vma->vm_start) 1325 return; 1326 1327 if (vma->vm_file) 1328 uprobe_munmap(vma, start, end); 1329 1330 if (unlikely(vma->vm_flags & VM_PFNMAP)) 1331 untrack_pfn(vma, 0, 0); 1332 1333 if (start != end) { 1334 if (unlikely(is_vm_hugetlb_page(vma))) { 1335 /* 1336 * It is undesirable to test vma->vm_file as it 1337 * should be non-null for valid hugetlb area. 1338 * However, vm_file will be NULL in the error 1339 * cleanup path of mmap_region. When 1340 * hugetlbfs ->mmap method fails, 1341 * mmap_region() nullifies vma->vm_file 1342 * before calling this function to clean up. 1343 * Since no pte has actually been setup, it is 1344 * safe to do nothing in this case. 1345 */ 1346 if (vma->vm_file) { 1347 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 1348 __unmap_hugepage_range_final(tlb, vma, start, end, NULL); 1349 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 1350 } 1351 } else 1352 unmap_page_range(tlb, vma, start, end, details); 1353 } 1354 } 1355 1356 /** 1357 * unmap_vmas - unmap a range of memory covered by a list of vma's 1358 * @tlb: address of the caller's struct mmu_gather 1359 * @vma: the starting vma 1360 * @start_addr: virtual address at which to start unmapping 1361 * @end_addr: virtual address at which to end unmapping 1362 * 1363 * Unmap all pages in the vma list. 1364 * 1365 * Only addresses between `start' and `end' will be unmapped. 1366 * 1367 * The VMA list must be sorted in ascending virtual address order. 1368 * 1369 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1370 * range after unmap_vmas() returns. So the only responsibility here is to 1371 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1372 * drops the lock and schedules. 1373 */ 1374 void unmap_vmas(struct mmu_gather *tlb, 1375 struct vm_area_struct *vma, unsigned long start_addr, 1376 unsigned long end_addr) 1377 { 1378 struct mm_struct *mm = vma->vm_mm; 1379 1380 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1381 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1382 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); 1383 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1384 } 1385 1386 /** 1387 * zap_page_range - remove user pages in a given range 1388 * @vma: vm_area_struct holding the applicable pages 1389 * @start: starting address of pages to zap 1390 * @size: number of bytes to zap 1391 * @details: details of nonlinear truncation or shared cache invalidation 1392 * 1393 * Caller must protect the VMA list 1394 */ 1395 void zap_page_range(struct vm_area_struct *vma, unsigned long start, 1396 unsigned long size, struct zap_details *details) 1397 { 1398 struct mm_struct *mm = vma->vm_mm; 1399 struct mmu_gather tlb; 1400 unsigned long end = start + size; 1401 1402 lru_add_drain(); 1403 tlb_gather_mmu(&tlb, mm, start, end); 1404 update_hiwater_rss(mm); 1405 mmu_notifier_invalidate_range_start(mm, start, end); 1406 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) 1407 unmap_single_vma(&tlb, vma, start, end, details); 1408 mmu_notifier_invalidate_range_end(mm, start, end); 1409 tlb_finish_mmu(&tlb, start, end); 1410 } 1411 1412 /** 1413 * zap_page_range_single - remove user pages in a given range 1414 * @vma: vm_area_struct holding the applicable pages 1415 * @address: starting address of pages to zap 1416 * @size: number of bytes to zap 1417 * @details: details of nonlinear truncation or shared cache invalidation 1418 * 1419 * The range must fit into one VMA. 1420 */ 1421 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1422 unsigned long size, struct zap_details *details) 1423 { 1424 struct mm_struct *mm = vma->vm_mm; 1425 struct mmu_gather tlb; 1426 unsigned long end = address + size; 1427 1428 lru_add_drain(); 1429 tlb_gather_mmu(&tlb, mm, address, end); 1430 update_hiwater_rss(mm); 1431 mmu_notifier_invalidate_range_start(mm, address, end); 1432 unmap_single_vma(&tlb, vma, address, end, details); 1433 mmu_notifier_invalidate_range_end(mm, address, end); 1434 tlb_finish_mmu(&tlb, address, end); 1435 } 1436 1437 /** 1438 * zap_vma_ptes - remove ptes mapping the vma 1439 * @vma: vm_area_struct holding ptes to be zapped 1440 * @address: starting address of pages to zap 1441 * @size: number of bytes to zap 1442 * 1443 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1444 * 1445 * The entire address range must be fully contained within the vma. 1446 * 1447 * Returns 0 if successful. 1448 */ 1449 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1450 unsigned long size) 1451 { 1452 if (address < vma->vm_start || address + size > vma->vm_end || 1453 !(vma->vm_flags & VM_PFNMAP)) 1454 return -1; 1455 zap_page_range_single(vma, address, size, NULL); 1456 return 0; 1457 } 1458 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1459 1460 /** 1461 * follow_page_mask - look up a page descriptor from a user-virtual address 1462 * @vma: vm_area_struct mapping @address 1463 * @address: virtual address to look up 1464 * @flags: flags modifying lookup behaviour 1465 * @page_mask: on output, *page_mask is set according to the size of the page 1466 * 1467 * @flags can have FOLL_ flags set, defined in <linux/mm.h> 1468 * 1469 * Returns the mapped (struct page *), %NULL if no mapping exists, or 1470 * an error pointer if there is a mapping to something not represented 1471 * by a page descriptor (see also vm_normal_page()). 1472 */ 1473 struct page *follow_page_mask(struct vm_area_struct *vma, 1474 unsigned long address, unsigned int flags, 1475 unsigned int *page_mask) 1476 { 1477 pgd_t *pgd; 1478 pud_t *pud; 1479 pmd_t *pmd; 1480 pte_t *ptep, pte; 1481 spinlock_t *ptl; 1482 struct page *page; 1483 struct mm_struct *mm = vma->vm_mm; 1484 1485 *page_mask = 0; 1486 1487 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 1488 if (!IS_ERR(page)) { 1489 BUG_ON(flags & FOLL_GET); 1490 goto out; 1491 } 1492 1493 page = NULL; 1494 pgd = pgd_offset(mm, address); 1495 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 1496 goto no_page_table; 1497 1498 pud = pud_offset(pgd, address); 1499 if (pud_none(*pud)) 1500 goto no_page_table; 1501 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { 1502 if (flags & FOLL_GET) 1503 goto out; 1504 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); 1505 goto out; 1506 } 1507 if (unlikely(pud_bad(*pud))) 1508 goto no_page_table; 1509 1510 pmd = pmd_offset(pud, address); 1511 if (pmd_none(*pmd)) 1512 goto no_page_table; 1513 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) { 1514 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 1515 if (flags & FOLL_GET) { 1516 /* 1517 * Refcount on tail pages are not well-defined and 1518 * shouldn't be taken. The caller should handle a NULL 1519 * return when trying to follow tail pages. 1520 */ 1521 if (PageHead(page)) 1522 get_page(page); 1523 else { 1524 page = NULL; 1525 goto out; 1526 } 1527 } 1528 goto out; 1529 } 1530 if ((flags & FOLL_NUMA) && pmd_numa(*pmd)) 1531 goto no_page_table; 1532 if (pmd_trans_huge(*pmd)) { 1533 if (flags & FOLL_SPLIT) { 1534 split_huge_page_pmd(vma, address, pmd); 1535 goto split_fallthrough; 1536 } 1537 ptl = pmd_lock(mm, pmd); 1538 if (likely(pmd_trans_huge(*pmd))) { 1539 if (unlikely(pmd_trans_splitting(*pmd))) { 1540 spin_unlock(ptl); 1541 wait_split_huge_page(vma->anon_vma, pmd); 1542 } else { 1543 page = follow_trans_huge_pmd(vma, address, 1544 pmd, flags); 1545 spin_unlock(ptl); 1546 *page_mask = HPAGE_PMD_NR - 1; 1547 goto out; 1548 } 1549 } else 1550 spin_unlock(ptl); 1551 /* fall through */ 1552 } 1553 split_fallthrough: 1554 if (unlikely(pmd_bad(*pmd))) 1555 goto no_page_table; 1556 1557 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 1558 1559 pte = *ptep; 1560 if (!pte_present(pte)) { 1561 swp_entry_t entry; 1562 /* 1563 * KSM's break_ksm() relies upon recognizing a ksm page 1564 * even while it is being migrated, so for that case we 1565 * need migration_entry_wait(). 1566 */ 1567 if (likely(!(flags & FOLL_MIGRATION))) 1568 goto no_page; 1569 if (pte_none(pte) || pte_file(pte)) 1570 goto no_page; 1571 entry = pte_to_swp_entry(pte); 1572 if (!is_migration_entry(entry)) 1573 goto no_page; 1574 pte_unmap_unlock(ptep, ptl); 1575 migration_entry_wait(mm, pmd, address); 1576 goto split_fallthrough; 1577 } 1578 if ((flags & FOLL_NUMA) && pte_numa(pte)) 1579 goto no_page; 1580 if ((flags & FOLL_WRITE) && !pte_write(pte)) 1581 goto unlock; 1582 1583 page = vm_normal_page(vma, address, pte); 1584 if (unlikely(!page)) { 1585 if ((flags & FOLL_DUMP) || 1586 !is_zero_pfn(pte_pfn(pte))) 1587 goto bad_page; 1588 page = pte_page(pte); 1589 } 1590 1591 if (flags & FOLL_GET) 1592 get_page_foll(page); 1593 if (flags & FOLL_TOUCH) { 1594 if ((flags & FOLL_WRITE) && 1595 !pte_dirty(pte) && !PageDirty(page)) 1596 set_page_dirty(page); 1597 /* 1598 * pte_mkyoung() would be more correct here, but atomic care 1599 * is needed to avoid losing the dirty bit: it is easier to use 1600 * mark_page_accessed(). 1601 */ 1602 mark_page_accessed(page); 1603 } 1604 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1605 /* 1606 * The preliminary mapping check is mainly to avoid the 1607 * pointless overhead of lock_page on the ZERO_PAGE 1608 * which might bounce very badly if there is contention. 1609 * 1610 * If the page is already locked, we don't need to 1611 * handle it now - vmscan will handle it later if and 1612 * when it attempts to reclaim the page. 1613 */ 1614 if (page->mapping && trylock_page(page)) { 1615 lru_add_drain(); /* push cached pages to LRU */ 1616 /* 1617 * Because we lock page here, and migration is 1618 * blocked by the pte's page reference, and we 1619 * know the page is still mapped, we don't even 1620 * need to check for file-cache page truncation. 1621 */ 1622 mlock_vma_page(page); 1623 unlock_page(page); 1624 } 1625 } 1626 unlock: 1627 pte_unmap_unlock(ptep, ptl); 1628 out: 1629 return page; 1630 1631 bad_page: 1632 pte_unmap_unlock(ptep, ptl); 1633 return ERR_PTR(-EFAULT); 1634 1635 no_page: 1636 pte_unmap_unlock(ptep, ptl); 1637 if (!pte_none(pte)) 1638 return page; 1639 1640 no_page_table: 1641 /* 1642 * When core dumping an enormous anonymous area that nobody 1643 * has touched so far, we don't want to allocate unnecessary pages or 1644 * page tables. Return error instead of NULL to skip handle_mm_fault, 1645 * then get_dump_page() will return NULL to leave a hole in the dump. 1646 * But we can only make this optimization where a hole would surely 1647 * be zero-filled if handle_mm_fault() actually did handle it. 1648 */ 1649 if ((flags & FOLL_DUMP) && 1650 (!vma->vm_ops || !vma->vm_ops->fault)) 1651 return ERR_PTR(-EFAULT); 1652 return page; 1653 } 1654 1655 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) 1656 { 1657 return stack_guard_page_start(vma, addr) || 1658 stack_guard_page_end(vma, addr+PAGE_SIZE); 1659 } 1660 1661 /** 1662 * __get_user_pages() - pin user pages in memory 1663 * @tsk: task_struct of target task 1664 * @mm: mm_struct of target mm 1665 * @start: starting user address 1666 * @nr_pages: number of pages from start to pin 1667 * @gup_flags: flags modifying pin behaviour 1668 * @pages: array that receives pointers to the pages pinned. 1669 * Should be at least nr_pages long. Or NULL, if caller 1670 * only intends to ensure the pages are faulted in. 1671 * @vmas: array of pointers to vmas corresponding to each page. 1672 * Or NULL if the caller does not require them. 1673 * @nonblocking: whether waiting for disk IO or mmap_sem contention 1674 * 1675 * Returns number of pages pinned. This may be fewer than the number 1676 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1677 * were pinned, returns -errno. Each page returned must be released 1678 * with a put_page() call when it is finished with. vmas will only 1679 * remain valid while mmap_sem is held. 1680 * 1681 * Must be called with mmap_sem held for read or write. 1682 * 1683 * __get_user_pages walks a process's page tables and takes a reference to 1684 * each struct page that each user address corresponds to at a given 1685 * instant. That is, it takes the page that would be accessed if a user 1686 * thread accesses the given user virtual address at that instant. 1687 * 1688 * This does not guarantee that the page exists in the user mappings when 1689 * __get_user_pages returns, and there may even be a completely different 1690 * page there in some cases (eg. if mmapped pagecache has been invalidated 1691 * and subsequently re faulted). However it does guarantee that the page 1692 * won't be freed completely. And mostly callers simply care that the page 1693 * contains data that was valid *at some point in time*. Typically, an IO 1694 * or similar operation cannot guarantee anything stronger anyway because 1695 * locks can't be held over the syscall boundary. 1696 * 1697 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If 1698 * the page is written to, set_page_dirty (or set_page_dirty_lock, as 1699 * appropriate) must be called after the page is finished with, and 1700 * before put_page is called. 1701 * 1702 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO 1703 * or mmap_sem contention, and if waiting is needed to pin all pages, 1704 * *@nonblocking will be set to 0. 1705 * 1706 * In most cases, get_user_pages or get_user_pages_fast should be used 1707 * instead of __get_user_pages. __get_user_pages should be used only if 1708 * you need some special @gup_flags. 1709 */ 1710 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1711 unsigned long start, unsigned long nr_pages, 1712 unsigned int gup_flags, struct page **pages, 1713 struct vm_area_struct **vmas, int *nonblocking) 1714 { 1715 long i; 1716 unsigned long vm_flags; 1717 unsigned int page_mask; 1718 1719 if (!nr_pages) 1720 return 0; 1721 1722 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); 1723 1724 /* 1725 * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault 1726 * would be called on PROT_NONE ranges. We must never invoke 1727 * handle_mm_fault on PROT_NONE ranges or the NUMA hinting 1728 * page faults would unprotect the PROT_NONE ranges if 1729 * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd 1730 * bitflag. So to avoid that, don't set FOLL_NUMA if 1731 * FOLL_FORCE is set. 1732 */ 1733 if (!(gup_flags & FOLL_FORCE)) 1734 gup_flags |= FOLL_NUMA; 1735 1736 i = 0; 1737 1738 do { 1739 struct vm_area_struct *vma; 1740 1741 vma = find_extend_vma(mm, start); 1742 if (!vma && in_gate_area(mm, start)) { 1743 unsigned long pg = start & PAGE_MASK; 1744 pgd_t *pgd; 1745 pud_t *pud; 1746 pmd_t *pmd; 1747 pte_t *pte; 1748 1749 /* user gate pages are read-only */ 1750 if (gup_flags & FOLL_WRITE) 1751 goto efault; 1752 if (pg > TASK_SIZE) 1753 pgd = pgd_offset_k(pg); 1754 else 1755 pgd = pgd_offset_gate(mm, pg); 1756 BUG_ON(pgd_none(*pgd)); 1757 pud = pud_offset(pgd, pg); 1758 BUG_ON(pud_none(*pud)); 1759 pmd = pmd_offset(pud, pg); 1760 if (pmd_none(*pmd)) 1761 goto efault; 1762 VM_BUG_ON(pmd_trans_huge(*pmd)); 1763 pte = pte_offset_map(pmd, pg); 1764 if (pte_none(*pte)) { 1765 pte_unmap(pte); 1766 goto efault; 1767 } 1768 vma = get_gate_vma(mm); 1769 if (pages) { 1770 struct page *page; 1771 1772 page = vm_normal_page(vma, start, *pte); 1773 if (!page) { 1774 if (!(gup_flags & FOLL_DUMP) && 1775 is_zero_pfn(pte_pfn(*pte))) 1776 page = pte_page(*pte); 1777 else { 1778 pte_unmap(pte); 1779 goto efault; 1780 } 1781 } 1782 pages[i] = page; 1783 get_page(page); 1784 } 1785 pte_unmap(pte); 1786 page_mask = 0; 1787 goto next_page; 1788 } 1789 1790 if (!vma) 1791 goto efault; 1792 vm_flags = vma->vm_flags; 1793 if (vm_flags & (VM_IO | VM_PFNMAP)) 1794 goto efault; 1795 1796 if (gup_flags & FOLL_WRITE) { 1797 if (!(vm_flags & VM_WRITE)) { 1798 if (!(gup_flags & FOLL_FORCE)) 1799 goto efault; 1800 /* 1801 * We used to let the write,force case do COW 1802 * in a VM_MAYWRITE VM_SHARED !VM_WRITE vma, so 1803 * ptrace could set a breakpoint in a read-only 1804 * mapping of an executable, without corrupting 1805 * the file (yet only when that file had been 1806 * opened for writing!). Anon pages in shared 1807 * mappings are surprising: now just reject it. 1808 */ 1809 if (!is_cow_mapping(vm_flags)) { 1810 WARN_ON_ONCE(vm_flags & VM_MAYWRITE); 1811 goto efault; 1812 } 1813 } 1814 } else { 1815 if (!(vm_flags & VM_READ)) { 1816 if (!(gup_flags & FOLL_FORCE)) 1817 goto efault; 1818 /* 1819 * Is there actually any vma we can reach here 1820 * which does not have VM_MAYREAD set? 1821 */ 1822 if (!(vm_flags & VM_MAYREAD)) 1823 goto efault; 1824 } 1825 } 1826 1827 if (is_vm_hugetlb_page(vma)) { 1828 i = follow_hugetlb_page(mm, vma, pages, vmas, 1829 &start, &nr_pages, i, gup_flags); 1830 continue; 1831 } 1832 1833 do { 1834 struct page *page; 1835 unsigned int foll_flags = gup_flags; 1836 unsigned int page_increm; 1837 1838 /* 1839 * If we have a pending SIGKILL, don't keep faulting 1840 * pages and potentially allocating memory. 1841 */ 1842 if (unlikely(fatal_signal_pending(current))) 1843 return i ? i : -ERESTARTSYS; 1844 1845 cond_resched(); 1846 while (!(page = follow_page_mask(vma, start, 1847 foll_flags, &page_mask))) { 1848 int ret; 1849 unsigned int fault_flags = 0; 1850 1851 /* For mlock, just skip the stack guard page. */ 1852 if (foll_flags & FOLL_MLOCK) { 1853 if (stack_guard_page(vma, start)) 1854 goto next_page; 1855 } 1856 if (foll_flags & FOLL_WRITE) 1857 fault_flags |= FAULT_FLAG_WRITE; 1858 if (nonblocking) 1859 fault_flags |= FAULT_FLAG_ALLOW_RETRY; 1860 if (foll_flags & FOLL_NOWAIT) 1861 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT); 1862 1863 ret = handle_mm_fault(mm, vma, start, 1864 fault_flags); 1865 1866 if (ret & VM_FAULT_ERROR) { 1867 if (ret & VM_FAULT_OOM) 1868 return i ? i : -ENOMEM; 1869 if (ret & (VM_FAULT_HWPOISON | 1870 VM_FAULT_HWPOISON_LARGE)) { 1871 if (i) 1872 return i; 1873 else if (gup_flags & FOLL_HWPOISON) 1874 return -EHWPOISON; 1875 else 1876 return -EFAULT; 1877 } 1878 if (ret & VM_FAULT_SIGBUS) 1879 goto efault; 1880 BUG(); 1881 } 1882 1883 if (tsk) { 1884 if (ret & VM_FAULT_MAJOR) 1885 tsk->maj_flt++; 1886 else 1887 tsk->min_flt++; 1888 } 1889 1890 if (ret & VM_FAULT_RETRY) { 1891 if (nonblocking) 1892 *nonblocking = 0; 1893 return i; 1894 } 1895 1896 /* 1897 * The VM_FAULT_WRITE bit tells us that 1898 * do_wp_page has broken COW when necessary, 1899 * even if maybe_mkwrite decided not to set 1900 * pte_write. We can thus safely do subsequent 1901 * page lookups as if they were reads. But only 1902 * do so when looping for pte_write is futile: 1903 * in some cases userspace may also be wanting 1904 * to write to the gotten user page, which a 1905 * read fault here might prevent (a readonly 1906 * page might get reCOWed by userspace write). 1907 */ 1908 if ((ret & VM_FAULT_WRITE) && 1909 !(vma->vm_flags & VM_WRITE)) 1910 foll_flags &= ~FOLL_WRITE; 1911 1912 cond_resched(); 1913 } 1914 if (IS_ERR(page)) 1915 return i ? i : PTR_ERR(page); 1916 if (pages) { 1917 pages[i] = page; 1918 1919 flush_anon_page(vma, page, start); 1920 flush_dcache_page(page); 1921 page_mask = 0; 1922 } 1923 next_page: 1924 if (vmas) { 1925 vmas[i] = vma; 1926 page_mask = 0; 1927 } 1928 page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask); 1929 if (page_increm > nr_pages) 1930 page_increm = nr_pages; 1931 i += page_increm; 1932 start += page_increm * PAGE_SIZE; 1933 nr_pages -= page_increm; 1934 } while (nr_pages && start < vma->vm_end); 1935 } while (nr_pages); 1936 return i; 1937 efault: 1938 return i ? : -EFAULT; 1939 } 1940 EXPORT_SYMBOL(__get_user_pages); 1941 1942 /* 1943 * fixup_user_fault() - manually resolve a user page fault 1944 * @tsk: the task_struct to use for page fault accounting, or 1945 * NULL if faults are not to be recorded. 1946 * @mm: mm_struct of target mm 1947 * @address: user address 1948 * @fault_flags:flags to pass down to handle_mm_fault() 1949 * 1950 * This is meant to be called in the specific scenario where for locking reasons 1951 * we try to access user memory in atomic context (within a pagefault_disable() 1952 * section), this returns -EFAULT, and we want to resolve the user fault before 1953 * trying again. 1954 * 1955 * Typically this is meant to be used by the futex code. 1956 * 1957 * The main difference with get_user_pages() is that this function will 1958 * unconditionally call handle_mm_fault() which will in turn perform all the 1959 * necessary SW fixup of the dirty and young bits in the PTE, while 1960 * handle_mm_fault() only guarantees to update these in the struct page. 1961 * 1962 * This is important for some architectures where those bits also gate the 1963 * access permission to the page because they are maintained in software. On 1964 * such architectures, gup() will not be enough to make a subsequent access 1965 * succeed. 1966 * 1967 * This should be called with the mm_sem held for read. 1968 */ 1969 int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, 1970 unsigned long address, unsigned int fault_flags) 1971 { 1972 struct vm_area_struct *vma; 1973 vm_flags_t vm_flags; 1974 int ret; 1975 1976 vma = find_extend_vma(mm, address); 1977 if (!vma || address < vma->vm_start) 1978 return -EFAULT; 1979 1980 vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ; 1981 if (!(vm_flags & vma->vm_flags)) 1982 return -EFAULT; 1983 1984 ret = handle_mm_fault(mm, vma, address, fault_flags); 1985 if (ret & VM_FAULT_ERROR) { 1986 if (ret & VM_FAULT_OOM) 1987 return -ENOMEM; 1988 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) 1989 return -EHWPOISON; 1990 if (ret & VM_FAULT_SIGBUS) 1991 return -EFAULT; 1992 BUG(); 1993 } 1994 if (tsk) { 1995 if (ret & VM_FAULT_MAJOR) 1996 tsk->maj_flt++; 1997 else 1998 tsk->min_flt++; 1999 } 2000 return 0; 2001 } 2002 2003 /* 2004 * get_user_pages() - pin user pages in memory 2005 * @tsk: the task_struct to use for page fault accounting, or 2006 * NULL if faults are not to be recorded. 2007 * @mm: mm_struct of target mm 2008 * @start: starting user address 2009 * @nr_pages: number of pages from start to pin 2010 * @write: whether pages will be written to by the caller 2011 * @force: whether to force access even when user mapping is currently 2012 * protected (but never forces write access to shared mapping). 2013 * @pages: array that receives pointers to the pages pinned. 2014 * Should be at least nr_pages long. Or NULL, if caller 2015 * only intends to ensure the pages are faulted in. 2016 * @vmas: array of pointers to vmas corresponding to each page. 2017 * Or NULL if the caller does not require them. 2018 * 2019 * Returns number of pages pinned. This may be fewer than the number 2020 * requested. If nr_pages is 0 or negative, returns 0. If no pages 2021 * were pinned, returns -errno. Each page returned must be released 2022 * with a put_page() call when it is finished with. vmas will only 2023 * remain valid while mmap_sem is held. 2024 * 2025 * Must be called with mmap_sem held for read or write. 2026 * 2027 * get_user_pages walks a process's page tables and takes a reference to 2028 * each struct page that each user address corresponds to at a given 2029 * instant. That is, it takes the page that would be accessed if a user 2030 * thread accesses the given user virtual address at that instant. 2031 * 2032 * This does not guarantee that the page exists in the user mappings when 2033 * get_user_pages returns, and there may even be a completely different 2034 * page there in some cases (eg. if mmapped pagecache has been invalidated 2035 * and subsequently re faulted). However it does guarantee that the page 2036 * won't be freed completely. And mostly callers simply care that the page 2037 * contains data that was valid *at some point in time*. Typically, an IO 2038 * or similar operation cannot guarantee anything stronger anyway because 2039 * locks can't be held over the syscall boundary. 2040 * 2041 * If write=0, the page must not be written to. If the page is written to, 2042 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called 2043 * after the page is finished with, and before put_page is called. 2044 * 2045 * get_user_pages is typically used for fewer-copy IO operations, to get a 2046 * handle on the memory by some means other than accesses via the user virtual 2047 * addresses. The pages may be submitted for DMA to devices or accessed via 2048 * their kernel linear mapping (via the kmap APIs). Care should be taken to 2049 * use the correct cache flushing APIs. 2050 * 2051 * See also get_user_pages_fast, for performance critical applications. 2052 */ 2053 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 2054 unsigned long start, unsigned long nr_pages, int write, 2055 int force, struct page **pages, struct vm_area_struct **vmas) 2056 { 2057 int flags = FOLL_TOUCH; 2058 2059 if (pages) 2060 flags |= FOLL_GET; 2061 if (write) 2062 flags |= FOLL_WRITE; 2063 if (force) 2064 flags |= FOLL_FORCE; 2065 2066 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 2067 NULL); 2068 } 2069 EXPORT_SYMBOL(get_user_pages); 2070 2071 /** 2072 * get_dump_page() - pin user page in memory while writing it to core dump 2073 * @addr: user address 2074 * 2075 * Returns struct page pointer of user page pinned for dump, 2076 * to be freed afterwards by page_cache_release() or put_page(). 2077 * 2078 * Returns NULL on any kind of failure - a hole must then be inserted into 2079 * the corefile, to preserve alignment with its headers; and also returns 2080 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - 2081 * allowing a hole to be left in the corefile to save diskspace. 2082 * 2083 * Called without mmap_sem, but after all other threads have been killed. 2084 */ 2085 #ifdef CONFIG_ELF_CORE 2086 struct page *get_dump_page(unsigned long addr) 2087 { 2088 struct vm_area_struct *vma; 2089 struct page *page; 2090 2091 if (__get_user_pages(current, current->mm, addr, 1, 2092 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma, 2093 NULL) < 1) 2094 return NULL; 2095 flush_cache_page(vma, addr, page_to_pfn(page)); 2096 return page; 2097 } 2098 #endif /* CONFIG_ELF_CORE */ 2099 2100 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 2101 spinlock_t **ptl) 2102 { 2103 pgd_t * pgd = pgd_offset(mm, addr); 2104 pud_t * pud = pud_alloc(mm, pgd, addr); 2105 if (pud) { 2106 pmd_t * pmd = pmd_alloc(mm, pud, addr); 2107 if (pmd) { 2108 VM_BUG_ON(pmd_trans_huge(*pmd)); 2109 return pte_alloc_map_lock(mm, pmd, addr, ptl); 2110 } 2111 } 2112 return NULL; 2113 } 2114 2115 /* 2116 * This is the old fallback for page remapping. 2117 * 2118 * For historical reasons, it only allows reserved pages. Only 2119 * old drivers should use this, and they needed to mark their 2120 * pages reserved for the old functions anyway. 2121 */ 2122 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 2123 struct page *page, pgprot_t prot) 2124 { 2125 struct mm_struct *mm = vma->vm_mm; 2126 int retval; 2127 pte_t *pte; 2128 spinlock_t *ptl; 2129 2130 retval = -EINVAL; 2131 if (PageAnon(page)) 2132 goto out; 2133 retval = -ENOMEM; 2134 flush_dcache_page(page); 2135 pte = get_locked_pte(mm, addr, &ptl); 2136 if (!pte) 2137 goto out; 2138 retval = -EBUSY; 2139 if (!pte_none(*pte)) 2140 goto out_unlock; 2141 2142 /* Ok, finally just insert the thing.. */ 2143 get_page(page); 2144 inc_mm_counter_fast(mm, MM_FILEPAGES); 2145 page_add_file_rmap(page); 2146 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 2147 2148 retval = 0; 2149 pte_unmap_unlock(pte, ptl); 2150 return retval; 2151 out_unlock: 2152 pte_unmap_unlock(pte, ptl); 2153 out: 2154 return retval; 2155 } 2156 2157 /** 2158 * vm_insert_page - insert single page into user vma 2159 * @vma: user vma to map to 2160 * @addr: target user address of this page 2161 * @page: source kernel page 2162 * 2163 * This allows drivers to insert individual pages they've allocated 2164 * into a user vma. 2165 * 2166 * The page has to be a nice clean _individual_ kernel allocation. 2167 * If you allocate a compound page, you need to have marked it as 2168 * such (__GFP_COMP), or manually just split the page up yourself 2169 * (see split_page()). 2170 * 2171 * NOTE! Traditionally this was done with "remap_pfn_range()" which 2172 * took an arbitrary page protection parameter. This doesn't allow 2173 * that. Your vma protection will have to be set up correctly, which 2174 * means that if you want a shared writable mapping, you'd better 2175 * ask for a shared writable mapping! 2176 * 2177 * The page does not need to be reserved. 2178 * 2179 * Usually this function is called from f_op->mmap() handler 2180 * under mm->mmap_sem write-lock, so it can change vma->vm_flags. 2181 * Caller must set VM_MIXEDMAP on vma if it wants to call this 2182 * function from other places, for example from page-fault handler. 2183 */ 2184 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 2185 struct page *page) 2186 { 2187 if (addr < vma->vm_start || addr >= vma->vm_end) 2188 return -EFAULT; 2189 if (!page_count(page)) 2190 return -EINVAL; 2191 if (!(vma->vm_flags & VM_MIXEDMAP)) { 2192 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); 2193 BUG_ON(vma->vm_flags & VM_PFNMAP); 2194 vma->vm_flags |= VM_MIXEDMAP; 2195 } 2196 return insert_page(vma, addr, page, vma->vm_page_prot); 2197 } 2198 EXPORT_SYMBOL(vm_insert_page); 2199 2200 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2201 unsigned long pfn, pgprot_t prot) 2202 { 2203 struct mm_struct *mm = vma->vm_mm; 2204 int retval; 2205 pte_t *pte, entry; 2206 spinlock_t *ptl; 2207 2208 retval = -ENOMEM; 2209 pte = get_locked_pte(mm, addr, &ptl); 2210 if (!pte) 2211 goto out; 2212 retval = -EBUSY; 2213 if (!pte_none(*pte)) 2214 goto out_unlock; 2215 2216 /* Ok, finally just insert the thing.. */ 2217 entry = pte_mkspecial(pfn_pte(pfn, prot)); 2218 set_pte_at(mm, addr, pte, entry); 2219 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 2220 2221 retval = 0; 2222 out_unlock: 2223 pte_unmap_unlock(pte, ptl); 2224 out: 2225 return retval; 2226 } 2227 2228 /** 2229 * vm_insert_pfn - insert single pfn into user vma 2230 * @vma: user vma to map to 2231 * @addr: target user address of this page 2232 * @pfn: source kernel pfn 2233 * 2234 * Similar to vm_insert_page, this allows drivers to insert individual pages 2235 * they've allocated into a user vma. Same comments apply. 2236 * 2237 * This function should only be called from a vm_ops->fault handler, and 2238 * in that case the handler should return NULL. 2239 * 2240 * vma cannot be a COW mapping. 2241 * 2242 * As this is called only for pages that do not currently exist, we 2243 * do not need to flush old virtual caches or the TLB. 2244 */ 2245 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2246 unsigned long pfn) 2247 { 2248 int ret; 2249 pgprot_t pgprot = vma->vm_page_prot; 2250 /* 2251 * Technically, architectures with pte_special can avoid all these 2252 * restrictions (same for remap_pfn_range). However we would like 2253 * consistency in testing and feature parity among all, so we should 2254 * try to keep these invariants in place for everybody. 2255 */ 2256 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 2257 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 2258 (VM_PFNMAP|VM_MIXEDMAP)); 2259 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 2260 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 2261 2262 if (addr < vma->vm_start || addr >= vma->vm_end) 2263 return -EFAULT; 2264 if (track_pfn_insert(vma, &pgprot, pfn)) 2265 return -EINVAL; 2266 2267 ret = insert_pfn(vma, addr, pfn, pgprot); 2268 2269 return ret; 2270 } 2271 EXPORT_SYMBOL(vm_insert_pfn); 2272 2273 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 2274 unsigned long pfn) 2275 { 2276 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 2277 2278 if (addr < vma->vm_start || addr >= vma->vm_end) 2279 return -EFAULT; 2280 2281 /* 2282 * If we don't have pte special, then we have to use the pfn_valid() 2283 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 2284 * refcount the page if pfn_valid is true (hence insert_page rather 2285 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 2286 * without pte special, it would there be refcounted as a normal page. 2287 */ 2288 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 2289 struct page *page; 2290 2291 page = pfn_to_page(pfn); 2292 return insert_page(vma, addr, page, vma->vm_page_prot); 2293 } 2294 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 2295 } 2296 EXPORT_SYMBOL(vm_insert_mixed); 2297 2298 /* 2299 * maps a range of physical memory into the requested pages. the old 2300 * mappings are removed. any references to nonexistent pages results 2301 * in null mappings (currently treated as "copy-on-access") 2302 */ 2303 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 2304 unsigned long addr, unsigned long end, 2305 unsigned long pfn, pgprot_t prot) 2306 { 2307 pte_t *pte; 2308 spinlock_t *ptl; 2309 2310 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 2311 if (!pte) 2312 return -ENOMEM; 2313 arch_enter_lazy_mmu_mode(); 2314 do { 2315 BUG_ON(!pte_none(*pte)); 2316 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 2317 pfn++; 2318 } while (pte++, addr += PAGE_SIZE, addr != end); 2319 arch_leave_lazy_mmu_mode(); 2320 pte_unmap_unlock(pte - 1, ptl); 2321 return 0; 2322 } 2323 2324 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 2325 unsigned long addr, unsigned long end, 2326 unsigned long pfn, pgprot_t prot) 2327 { 2328 pmd_t *pmd; 2329 unsigned long next; 2330 2331 pfn -= addr >> PAGE_SHIFT; 2332 pmd = pmd_alloc(mm, pud, addr); 2333 if (!pmd) 2334 return -ENOMEM; 2335 VM_BUG_ON(pmd_trans_huge(*pmd)); 2336 do { 2337 next = pmd_addr_end(addr, end); 2338 if (remap_pte_range(mm, pmd, addr, next, 2339 pfn + (addr >> PAGE_SHIFT), prot)) 2340 return -ENOMEM; 2341 } while (pmd++, addr = next, addr != end); 2342 return 0; 2343 } 2344 2345 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 2346 unsigned long addr, unsigned long end, 2347 unsigned long pfn, pgprot_t prot) 2348 { 2349 pud_t *pud; 2350 unsigned long next; 2351 2352 pfn -= addr >> PAGE_SHIFT; 2353 pud = pud_alloc(mm, pgd, addr); 2354 if (!pud) 2355 return -ENOMEM; 2356 do { 2357 next = pud_addr_end(addr, end); 2358 if (remap_pmd_range(mm, pud, addr, next, 2359 pfn + (addr >> PAGE_SHIFT), prot)) 2360 return -ENOMEM; 2361 } while (pud++, addr = next, addr != end); 2362 return 0; 2363 } 2364 2365 /** 2366 * remap_pfn_range - remap kernel memory to userspace 2367 * @vma: user vma to map to 2368 * @addr: target user address to start at 2369 * @pfn: physical address of kernel memory 2370 * @size: size of map area 2371 * @prot: page protection flags for this mapping 2372 * 2373 * Note: this is only safe if the mm semaphore is held when called. 2374 */ 2375 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 2376 unsigned long pfn, unsigned long size, pgprot_t prot) 2377 { 2378 pgd_t *pgd; 2379 unsigned long next; 2380 unsigned long end = addr + PAGE_ALIGN(size); 2381 struct mm_struct *mm = vma->vm_mm; 2382 int err; 2383 2384 /* 2385 * Physically remapped pages are special. Tell the 2386 * rest of the world about it: 2387 * VM_IO tells people not to look at these pages 2388 * (accesses can have side effects). 2389 * VM_PFNMAP tells the core MM that the base pages are just 2390 * raw PFN mappings, and do not have a "struct page" associated 2391 * with them. 2392 * VM_DONTEXPAND 2393 * Disable vma merging and expanding with mremap(). 2394 * VM_DONTDUMP 2395 * Omit vma from core dump, even when VM_IO turned off. 2396 * 2397 * There's a horrible special case to handle copy-on-write 2398 * behaviour that some programs depend on. We mark the "original" 2399 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 2400 * See vm_normal_page() for details. 2401 */ 2402 if (is_cow_mapping(vma->vm_flags)) { 2403 if (addr != vma->vm_start || end != vma->vm_end) 2404 return -EINVAL; 2405 vma->vm_pgoff = pfn; 2406 } 2407 2408 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); 2409 if (err) 2410 return -EINVAL; 2411 2412 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 2413 2414 BUG_ON(addr >= end); 2415 pfn -= addr >> PAGE_SHIFT; 2416 pgd = pgd_offset(mm, addr); 2417 flush_cache_range(vma, addr, end); 2418 do { 2419 next = pgd_addr_end(addr, end); 2420 err = remap_pud_range(mm, pgd, addr, next, 2421 pfn + (addr >> PAGE_SHIFT), prot); 2422 if (err) 2423 break; 2424 } while (pgd++, addr = next, addr != end); 2425 2426 if (err) 2427 untrack_pfn(vma, pfn, PAGE_ALIGN(size)); 2428 2429 return err; 2430 } 2431 EXPORT_SYMBOL(remap_pfn_range); 2432 2433 /** 2434 * vm_iomap_memory - remap memory to userspace 2435 * @vma: user vma to map to 2436 * @start: start of area 2437 * @len: size of area 2438 * 2439 * This is a simplified io_remap_pfn_range() for common driver use. The 2440 * driver just needs to give us the physical memory range to be mapped, 2441 * we'll figure out the rest from the vma information. 2442 * 2443 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get 2444 * whatever write-combining details or similar. 2445 */ 2446 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 2447 { 2448 unsigned long vm_len, pfn, pages; 2449 2450 /* Check that the physical memory area passed in looks valid */ 2451 if (start + len < start) 2452 return -EINVAL; 2453 /* 2454 * You *really* shouldn't map things that aren't page-aligned, 2455 * but we've historically allowed it because IO memory might 2456 * just have smaller alignment. 2457 */ 2458 len += start & ~PAGE_MASK; 2459 pfn = start >> PAGE_SHIFT; 2460 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; 2461 if (pfn + pages < pfn) 2462 return -EINVAL; 2463 2464 /* We start the mapping 'vm_pgoff' pages into the area */ 2465 if (vma->vm_pgoff > pages) 2466 return -EINVAL; 2467 pfn += vma->vm_pgoff; 2468 pages -= vma->vm_pgoff; 2469 2470 /* Can we fit all of the mapping? */ 2471 vm_len = vma->vm_end - vma->vm_start; 2472 if (vm_len >> PAGE_SHIFT > pages) 2473 return -EINVAL; 2474 2475 /* Ok, let it rip */ 2476 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 2477 } 2478 EXPORT_SYMBOL(vm_iomap_memory); 2479 2480 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 2481 unsigned long addr, unsigned long end, 2482 pte_fn_t fn, void *data) 2483 { 2484 pte_t *pte; 2485 int err; 2486 pgtable_t token; 2487 spinlock_t *uninitialized_var(ptl); 2488 2489 pte = (mm == &init_mm) ? 2490 pte_alloc_kernel(pmd, addr) : 2491 pte_alloc_map_lock(mm, pmd, addr, &ptl); 2492 if (!pte) 2493 return -ENOMEM; 2494 2495 BUG_ON(pmd_huge(*pmd)); 2496 2497 arch_enter_lazy_mmu_mode(); 2498 2499 token = pmd_pgtable(*pmd); 2500 2501 do { 2502 err = fn(pte++, token, addr, data); 2503 if (err) 2504 break; 2505 } while (addr += PAGE_SIZE, addr != end); 2506 2507 arch_leave_lazy_mmu_mode(); 2508 2509 if (mm != &init_mm) 2510 pte_unmap_unlock(pte-1, ptl); 2511 return err; 2512 } 2513 2514 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 2515 unsigned long addr, unsigned long end, 2516 pte_fn_t fn, void *data) 2517 { 2518 pmd_t *pmd; 2519 unsigned long next; 2520 int err; 2521 2522 BUG_ON(pud_huge(*pud)); 2523 2524 pmd = pmd_alloc(mm, pud, addr); 2525 if (!pmd) 2526 return -ENOMEM; 2527 do { 2528 next = pmd_addr_end(addr, end); 2529 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 2530 if (err) 2531 break; 2532 } while (pmd++, addr = next, addr != end); 2533 return err; 2534 } 2535 2536 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 2537 unsigned long addr, unsigned long end, 2538 pte_fn_t fn, void *data) 2539 { 2540 pud_t *pud; 2541 unsigned long next; 2542 int err; 2543 2544 pud = pud_alloc(mm, pgd, addr); 2545 if (!pud) 2546 return -ENOMEM; 2547 do { 2548 next = pud_addr_end(addr, end); 2549 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 2550 if (err) 2551 break; 2552 } while (pud++, addr = next, addr != end); 2553 return err; 2554 } 2555 2556 /* 2557 * Scan a region of virtual memory, filling in page tables as necessary 2558 * and calling a provided function on each leaf page table. 2559 */ 2560 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2561 unsigned long size, pte_fn_t fn, void *data) 2562 { 2563 pgd_t *pgd; 2564 unsigned long next; 2565 unsigned long end = addr + size; 2566 int err; 2567 2568 BUG_ON(addr >= end); 2569 pgd = pgd_offset(mm, addr); 2570 do { 2571 next = pgd_addr_end(addr, end); 2572 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 2573 if (err) 2574 break; 2575 } while (pgd++, addr = next, addr != end); 2576 2577 return err; 2578 } 2579 EXPORT_SYMBOL_GPL(apply_to_page_range); 2580 2581 /* 2582 * handle_pte_fault chooses page fault handler according to an entry 2583 * which was read non-atomically. Before making any commitment, on 2584 * those architectures or configurations (e.g. i386 with PAE) which 2585 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault 2586 * must check under lock before unmapping the pte and proceeding 2587 * (but do_wp_page is only called after already making such a check; 2588 * and do_anonymous_page can safely check later on). 2589 */ 2590 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 2591 pte_t *page_table, pte_t orig_pte) 2592 { 2593 int same = 1; 2594 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 2595 if (sizeof(pte_t) > sizeof(unsigned long)) { 2596 spinlock_t *ptl = pte_lockptr(mm, pmd); 2597 spin_lock(ptl); 2598 same = pte_same(*page_table, orig_pte); 2599 spin_unlock(ptl); 2600 } 2601 #endif 2602 pte_unmap(page_table); 2603 return same; 2604 } 2605 2606 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 2607 { 2608 debug_dma_assert_idle(src); 2609 2610 /* 2611 * If the source page was a PFN mapping, we don't have 2612 * a "struct page" for it. We do a best-effort copy by 2613 * just copying from the original user address. If that 2614 * fails, we just zero-fill it. Live with it. 2615 */ 2616 if (unlikely(!src)) { 2617 void *kaddr = kmap_atomic(dst); 2618 void __user *uaddr = (void __user *)(va & PAGE_MASK); 2619 2620 /* 2621 * This really shouldn't fail, because the page is there 2622 * in the page tables. But it might just be unreadable, 2623 * in which case we just give up and fill the result with 2624 * zeroes. 2625 */ 2626 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 2627 clear_page(kaddr); 2628 kunmap_atomic(kaddr); 2629 flush_dcache_page(dst); 2630 } else 2631 copy_user_highpage(dst, src, va, vma); 2632 } 2633 2634 /* 2635 * Notify the address space that the page is about to become writable so that 2636 * it can prohibit this or wait for the page to get into an appropriate state. 2637 * 2638 * We do this without the lock held, so that it can sleep if it needs to. 2639 */ 2640 static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page, 2641 unsigned long address) 2642 { 2643 struct vm_fault vmf; 2644 int ret; 2645 2646 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2647 vmf.pgoff = page->index; 2648 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2649 vmf.page = page; 2650 2651 ret = vma->vm_ops->page_mkwrite(vma, &vmf); 2652 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2653 return ret; 2654 if (unlikely(!(ret & VM_FAULT_LOCKED))) { 2655 lock_page(page); 2656 if (!page->mapping) { 2657 unlock_page(page); 2658 return 0; /* retry */ 2659 } 2660 ret |= VM_FAULT_LOCKED; 2661 } else 2662 VM_BUG_ON_PAGE(!PageLocked(page), page); 2663 return ret; 2664 } 2665 2666 /* 2667 * This routine handles present pages, when users try to write 2668 * to a shared page. It is done by copying the page to a new address 2669 * and decrementing the shared-page counter for the old page. 2670 * 2671 * Note that this routine assumes that the protection checks have been 2672 * done by the caller (the low-level page fault routine in most cases). 2673 * Thus we can safely just mark it writable once we've done any necessary 2674 * COW. 2675 * 2676 * We also mark the page dirty at this point even though the page will 2677 * change only once the write actually happens. This avoids a few races, 2678 * and potentially makes it more efficient. 2679 * 2680 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2681 * but allow concurrent faults), with pte both mapped and locked. 2682 * We return with mmap_sem still held, but pte unmapped and unlocked. 2683 */ 2684 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 2685 unsigned long address, pte_t *page_table, pmd_t *pmd, 2686 spinlock_t *ptl, pte_t orig_pte) 2687 __releases(ptl) 2688 { 2689 struct page *old_page, *new_page = NULL; 2690 pte_t entry; 2691 int ret = 0; 2692 int page_mkwrite = 0; 2693 struct page *dirty_page = NULL; 2694 unsigned long mmun_start = 0; /* For mmu_notifiers */ 2695 unsigned long mmun_end = 0; /* For mmu_notifiers */ 2696 2697 old_page = vm_normal_page(vma, address, orig_pte); 2698 if (!old_page) { 2699 /* 2700 * VM_MIXEDMAP !pfn_valid() case 2701 * 2702 * We should not cow pages in a shared writeable mapping. 2703 * Just mark the pages writable as we can't do any dirty 2704 * accounting on raw pfn maps. 2705 */ 2706 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2707 (VM_WRITE|VM_SHARED)) 2708 goto reuse; 2709 goto gotten; 2710 } 2711 2712 /* 2713 * Take out anonymous pages first, anonymous shared vmas are 2714 * not dirty accountable. 2715 */ 2716 if (PageAnon(old_page) && !PageKsm(old_page)) { 2717 if (!trylock_page(old_page)) { 2718 page_cache_get(old_page); 2719 pte_unmap_unlock(page_table, ptl); 2720 lock_page(old_page); 2721 page_table = pte_offset_map_lock(mm, pmd, address, 2722 &ptl); 2723 if (!pte_same(*page_table, orig_pte)) { 2724 unlock_page(old_page); 2725 goto unlock; 2726 } 2727 page_cache_release(old_page); 2728 } 2729 if (reuse_swap_page(old_page)) { 2730 /* 2731 * The page is all ours. Move it to our anon_vma so 2732 * the rmap code will not search our parent or siblings. 2733 * Protected against the rmap code by the page lock. 2734 */ 2735 page_move_anon_rmap(old_page, vma, address); 2736 unlock_page(old_page); 2737 goto reuse; 2738 } 2739 unlock_page(old_page); 2740 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2741 (VM_WRITE|VM_SHARED))) { 2742 /* 2743 * Only catch write-faults on shared writable pages, 2744 * read-only shared pages can get COWed by 2745 * get_user_pages(.write=1, .force=1). 2746 */ 2747 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2748 int tmp; 2749 page_cache_get(old_page); 2750 pte_unmap_unlock(page_table, ptl); 2751 tmp = do_page_mkwrite(vma, old_page, address); 2752 if (unlikely(!tmp || (tmp & 2753 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 2754 page_cache_release(old_page); 2755 return tmp; 2756 } 2757 /* 2758 * Since we dropped the lock we need to revalidate 2759 * the PTE as someone else may have changed it. If 2760 * they did, we just return, as we can count on the 2761 * MMU to tell us if they didn't also make it writable. 2762 */ 2763 page_table = pte_offset_map_lock(mm, pmd, address, 2764 &ptl); 2765 if (!pte_same(*page_table, orig_pte)) { 2766 unlock_page(old_page); 2767 goto unlock; 2768 } 2769 2770 page_mkwrite = 1; 2771 } 2772 dirty_page = old_page; 2773 get_page(dirty_page); 2774 2775 reuse: 2776 /* 2777 * Clear the pages cpupid information as the existing 2778 * information potentially belongs to a now completely 2779 * unrelated process. 2780 */ 2781 if (old_page) 2782 page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1); 2783 2784 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2785 entry = pte_mkyoung(orig_pte); 2786 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2787 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2788 update_mmu_cache(vma, address, page_table); 2789 pte_unmap_unlock(page_table, ptl); 2790 ret |= VM_FAULT_WRITE; 2791 2792 if (!dirty_page) 2793 return ret; 2794 2795 /* 2796 * Yes, Virginia, this is actually required to prevent a race 2797 * with clear_page_dirty_for_io() from clearing the page dirty 2798 * bit after it clear all dirty ptes, but before a racing 2799 * do_wp_page installs a dirty pte. 2800 * 2801 * do_shared_fault is protected similarly. 2802 */ 2803 if (!page_mkwrite) { 2804 wait_on_page_locked(dirty_page); 2805 set_page_dirty_balance(dirty_page); 2806 /* file_update_time outside page_lock */ 2807 if (vma->vm_file) 2808 file_update_time(vma->vm_file); 2809 } 2810 put_page(dirty_page); 2811 if (page_mkwrite) { 2812 struct address_space *mapping = dirty_page->mapping; 2813 2814 set_page_dirty(dirty_page); 2815 unlock_page(dirty_page); 2816 page_cache_release(dirty_page); 2817 if (mapping) { 2818 /* 2819 * Some device drivers do not set page.mapping 2820 * but still dirty their pages 2821 */ 2822 balance_dirty_pages_ratelimited(mapping); 2823 } 2824 } 2825 2826 return ret; 2827 } 2828 2829 /* 2830 * Ok, we need to copy. Oh, well.. 2831 */ 2832 page_cache_get(old_page); 2833 gotten: 2834 pte_unmap_unlock(page_table, ptl); 2835 2836 if (unlikely(anon_vma_prepare(vma))) 2837 goto oom; 2838 2839 if (is_zero_pfn(pte_pfn(orig_pte))) { 2840 new_page = alloc_zeroed_user_highpage_movable(vma, address); 2841 if (!new_page) 2842 goto oom; 2843 } else { 2844 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2845 if (!new_page) 2846 goto oom; 2847 cow_user_page(new_page, old_page, address, vma); 2848 } 2849 __SetPageUptodate(new_page); 2850 2851 if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) 2852 goto oom_free_new; 2853 2854 mmun_start = address & PAGE_MASK; 2855 mmun_end = mmun_start + PAGE_SIZE; 2856 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2857 2858 /* 2859 * Re-check the pte - we dropped the lock 2860 */ 2861 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2862 if (likely(pte_same(*page_table, orig_pte))) { 2863 if (old_page) { 2864 if (!PageAnon(old_page)) { 2865 dec_mm_counter_fast(mm, MM_FILEPAGES); 2866 inc_mm_counter_fast(mm, MM_ANONPAGES); 2867 } 2868 } else 2869 inc_mm_counter_fast(mm, MM_ANONPAGES); 2870 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2871 entry = mk_pte(new_page, vma->vm_page_prot); 2872 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2873 /* 2874 * Clear the pte entry and flush it first, before updating the 2875 * pte with the new entry. This will avoid a race condition 2876 * seen in the presence of one thread doing SMC and another 2877 * thread doing COW. 2878 */ 2879 ptep_clear_flush(vma, address, page_table); 2880 page_add_new_anon_rmap(new_page, vma, address); 2881 /* 2882 * We call the notify macro here because, when using secondary 2883 * mmu page tables (such as kvm shadow page tables), we want the 2884 * new page to be mapped directly into the secondary page table. 2885 */ 2886 set_pte_at_notify(mm, address, page_table, entry); 2887 update_mmu_cache(vma, address, page_table); 2888 if (old_page) { 2889 /* 2890 * Only after switching the pte to the new page may 2891 * we remove the mapcount here. Otherwise another 2892 * process may come and find the rmap count decremented 2893 * before the pte is switched to the new page, and 2894 * "reuse" the old page writing into it while our pte 2895 * here still points into it and can be read by other 2896 * threads. 2897 * 2898 * The critical issue is to order this 2899 * page_remove_rmap with the ptp_clear_flush above. 2900 * Those stores are ordered by (if nothing else,) 2901 * the barrier present in the atomic_add_negative 2902 * in page_remove_rmap. 2903 * 2904 * Then the TLB flush in ptep_clear_flush ensures that 2905 * no process can access the old page before the 2906 * decremented mapcount is visible. And the old page 2907 * cannot be reused until after the decremented 2908 * mapcount is visible. So transitively, TLBs to 2909 * old page will be flushed before it can be reused. 2910 */ 2911 page_remove_rmap(old_page); 2912 } 2913 2914 /* Free the old page.. */ 2915 new_page = old_page; 2916 ret |= VM_FAULT_WRITE; 2917 } else 2918 mem_cgroup_uncharge_page(new_page); 2919 2920 if (new_page) 2921 page_cache_release(new_page); 2922 unlock: 2923 pte_unmap_unlock(page_table, ptl); 2924 if (mmun_end > mmun_start) 2925 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2926 if (old_page) { 2927 /* 2928 * Don't let another task, with possibly unlocked vma, 2929 * keep the mlocked page. 2930 */ 2931 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { 2932 lock_page(old_page); /* LRU manipulation */ 2933 munlock_vma_page(old_page); 2934 unlock_page(old_page); 2935 } 2936 page_cache_release(old_page); 2937 } 2938 return ret; 2939 oom_free_new: 2940 page_cache_release(new_page); 2941 oom: 2942 if (old_page) 2943 page_cache_release(old_page); 2944 return VM_FAULT_OOM; 2945 } 2946 2947 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 2948 unsigned long start_addr, unsigned long end_addr, 2949 struct zap_details *details) 2950 { 2951 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 2952 } 2953 2954 static inline void unmap_mapping_range_tree(struct rb_root *root, 2955 struct zap_details *details) 2956 { 2957 struct vm_area_struct *vma; 2958 pgoff_t vba, vea, zba, zea; 2959 2960 vma_interval_tree_foreach(vma, root, 2961 details->first_index, details->last_index) { 2962 2963 vba = vma->vm_pgoff; 2964 vea = vba + vma_pages(vma) - 1; 2965 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2966 zba = details->first_index; 2967 if (zba < vba) 2968 zba = vba; 2969 zea = details->last_index; 2970 if (zea > vea) 2971 zea = vea; 2972 2973 unmap_mapping_range_vma(vma, 2974 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2975 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2976 details); 2977 } 2978 } 2979 2980 static inline void unmap_mapping_range_list(struct list_head *head, 2981 struct zap_details *details) 2982 { 2983 struct vm_area_struct *vma; 2984 2985 /* 2986 * In nonlinear VMAs there is no correspondence between virtual address 2987 * offset and file offset. So we must perform an exhaustive search 2988 * across *all* the pages in each nonlinear VMA, not just the pages 2989 * whose virtual address lies outside the file truncation point. 2990 */ 2991 list_for_each_entry(vma, head, shared.nonlinear) { 2992 details->nonlinear_vma = vma; 2993 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details); 2994 } 2995 } 2996 2997 /** 2998 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2999 * @mapping: the address space containing mmaps to be unmapped. 3000 * @holebegin: byte in first page to unmap, relative to the start of 3001 * the underlying file. This will be rounded down to a PAGE_SIZE 3002 * boundary. Note that this is different from truncate_pagecache(), which 3003 * must keep the partial page. In contrast, we must get rid of 3004 * partial pages. 3005 * @holelen: size of prospective hole in bytes. This will be rounded 3006 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 3007 * end of the file. 3008 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 3009 * but 0 when invalidating pagecache, don't throw away private data. 3010 */ 3011 void unmap_mapping_range(struct address_space *mapping, 3012 loff_t const holebegin, loff_t const holelen, int even_cows) 3013 { 3014 struct zap_details details; 3015 pgoff_t hba = holebegin >> PAGE_SHIFT; 3016 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 3017 3018 /* Check for overflow. */ 3019 if (sizeof(holelen) > sizeof(hlen)) { 3020 long long holeend = 3021 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 3022 if (holeend & ~(long long)ULONG_MAX) 3023 hlen = ULONG_MAX - hba + 1; 3024 } 3025 3026 details.check_mapping = even_cows? NULL: mapping; 3027 details.nonlinear_vma = NULL; 3028 details.first_index = hba; 3029 details.last_index = hba + hlen - 1; 3030 if (details.last_index < details.first_index) 3031 details.last_index = ULONG_MAX; 3032 3033 3034 mutex_lock(&mapping->i_mmap_mutex); 3035 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) 3036 unmap_mapping_range_tree(&mapping->i_mmap, &details); 3037 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 3038 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 3039 mutex_unlock(&mapping->i_mmap_mutex); 3040 } 3041 EXPORT_SYMBOL(unmap_mapping_range); 3042 3043 /* 3044 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3045 * but allow concurrent faults), and pte mapped but not yet locked. 3046 * We return with mmap_sem still held, but pte unmapped and unlocked. 3047 */ 3048 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 3049 unsigned long address, pte_t *page_table, pmd_t *pmd, 3050 unsigned int flags, pte_t orig_pte) 3051 { 3052 spinlock_t *ptl; 3053 struct page *page, *swapcache; 3054 swp_entry_t entry; 3055 pte_t pte; 3056 int locked; 3057 struct mem_cgroup *ptr; 3058 int exclusive = 0; 3059 int ret = 0; 3060 3061 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3062 goto out; 3063 3064 entry = pte_to_swp_entry(orig_pte); 3065 if (unlikely(non_swap_entry(entry))) { 3066 if (is_migration_entry(entry)) { 3067 migration_entry_wait(mm, pmd, address); 3068 } else if (is_hwpoison_entry(entry)) { 3069 ret = VM_FAULT_HWPOISON; 3070 } else { 3071 print_bad_pte(vma, address, orig_pte, NULL); 3072 ret = VM_FAULT_SIGBUS; 3073 } 3074 goto out; 3075 } 3076 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 3077 page = lookup_swap_cache(entry); 3078 if (!page) { 3079 page = swapin_readahead(entry, 3080 GFP_HIGHUSER_MOVABLE, vma, address); 3081 if (!page) { 3082 /* 3083 * Back out if somebody else faulted in this pte 3084 * while we released the pte lock. 3085 */ 3086 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3087 if (likely(pte_same(*page_table, orig_pte))) 3088 ret = VM_FAULT_OOM; 3089 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 3090 goto unlock; 3091 } 3092 3093 /* Had to read the page from swap area: Major fault */ 3094 ret = VM_FAULT_MAJOR; 3095 count_vm_event(PGMAJFAULT); 3096 mem_cgroup_count_vm_event(mm, PGMAJFAULT); 3097 } else if (PageHWPoison(page)) { 3098 /* 3099 * hwpoisoned dirty swapcache pages are kept for killing 3100 * owner processes (which may be unknown at hwpoison time) 3101 */ 3102 ret = VM_FAULT_HWPOISON; 3103 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 3104 swapcache = page; 3105 goto out_release; 3106 } 3107 3108 swapcache = page; 3109 locked = lock_page_or_retry(page, mm, flags); 3110 3111 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 3112 if (!locked) { 3113 ret |= VM_FAULT_RETRY; 3114 goto out_release; 3115 } 3116 3117 /* 3118 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 3119 * release the swapcache from under us. The page pin, and pte_same 3120 * test below, are not enough to exclude that. Even if it is still 3121 * swapcache, we need to check that the page's swap has not changed. 3122 */ 3123 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) 3124 goto out_page; 3125 3126 page = ksm_might_need_to_copy(page, vma, address); 3127 if (unlikely(!page)) { 3128 ret = VM_FAULT_OOM; 3129 page = swapcache; 3130 goto out_page; 3131 } 3132 3133 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { 3134 ret = VM_FAULT_OOM; 3135 goto out_page; 3136 } 3137 3138 /* 3139 * Back out if somebody else already faulted in this pte. 3140 */ 3141 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3142 if (unlikely(!pte_same(*page_table, orig_pte))) 3143 goto out_nomap; 3144 3145 if (unlikely(!PageUptodate(page))) { 3146 ret = VM_FAULT_SIGBUS; 3147 goto out_nomap; 3148 } 3149 3150 /* 3151 * The page isn't present yet, go ahead with the fault. 3152 * 3153 * Be careful about the sequence of operations here. 3154 * To get its accounting right, reuse_swap_page() must be called 3155 * while the page is counted on swap but not yet in mapcount i.e. 3156 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 3157 * must be called after the swap_free(), or it will never succeed. 3158 * Because delete_from_swap_page() may be called by reuse_swap_page(), 3159 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry 3160 * in page->private. In this case, a record in swap_cgroup is silently 3161 * discarded at swap_free(). 3162 */ 3163 3164 inc_mm_counter_fast(mm, MM_ANONPAGES); 3165 dec_mm_counter_fast(mm, MM_SWAPENTS); 3166 pte = mk_pte(page, vma->vm_page_prot); 3167 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 3168 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 3169 flags &= ~FAULT_FLAG_WRITE; 3170 ret |= VM_FAULT_WRITE; 3171 exclusive = 1; 3172 } 3173 flush_icache_page(vma, page); 3174 if (pte_swp_soft_dirty(orig_pte)) 3175 pte = pte_mksoft_dirty(pte); 3176 set_pte_at(mm, address, page_table, pte); 3177 if (page == swapcache) 3178 do_page_add_anon_rmap(page, vma, address, exclusive); 3179 else /* ksm created a completely new copy */ 3180 page_add_new_anon_rmap(page, vma, address); 3181 /* It's better to call commit-charge after rmap is established */ 3182 mem_cgroup_commit_charge_swapin(page, ptr); 3183 3184 swap_free(entry); 3185 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 3186 try_to_free_swap(page); 3187 unlock_page(page); 3188 if (page != swapcache) { 3189 /* 3190 * Hold the lock to avoid the swap entry to be reused 3191 * until we take the PT lock for the pte_same() check 3192 * (to avoid false positives from pte_same). For 3193 * further safety release the lock after the swap_free 3194 * so that the swap count won't change under a 3195 * parallel locked swapcache. 3196 */ 3197 unlock_page(swapcache); 3198 page_cache_release(swapcache); 3199 } 3200 3201 if (flags & FAULT_FLAG_WRITE) { 3202 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 3203 if (ret & VM_FAULT_ERROR) 3204 ret &= VM_FAULT_ERROR; 3205 goto out; 3206 } 3207 3208 /* No need to invalidate - it was non-present before */ 3209 update_mmu_cache(vma, address, page_table); 3210 unlock: 3211 pte_unmap_unlock(page_table, ptl); 3212 out: 3213 return ret; 3214 out_nomap: 3215 mem_cgroup_cancel_charge_swapin(ptr); 3216 pte_unmap_unlock(page_table, ptl); 3217 out_page: 3218 unlock_page(page); 3219 out_release: 3220 page_cache_release(page); 3221 if (page != swapcache) { 3222 unlock_page(swapcache); 3223 page_cache_release(swapcache); 3224 } 3225 return ret; 3226 } 3227 3228 /* 3229 * This is like a special single-page "expand_{down|up}wards()", 3230 * except we must first make sure that 'address{-|+}PAGE_SIZE' 3231 * doesn't hit another vma. 3232 */ 3233 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) 3234 { 3235 address &= PAGE_MASK; 3236 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { 3237 struct vm_area_struct *prev = vma->vm_prev; 3238 3239 /* 3240 * Is there a mapping abutting this one below? 3241 * 3242 * That's only ok if it's the same stack mapping 3243 * that has gotten split.. 3244 */ 3245 if (prev && prev->vm_end == address) 3246 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; 3247 3248 expand_downwards(vma, address - PAGE_SIZE); 3249 } 3250 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { 3251 struct vm_area_struct *next = vma->vm_next; 3252 3253 /* As VM_GROWSDOWN but s/below/above/ */ 3254 if (next && next->vm_start == address + PAGE_SIZE) 3255 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; 3256 3257 expand_upwards(vma, address + PAGE_SIZE); 3258 } 3259 return 0; 3260 } 3261 3262 /* 3263 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3264 * but allow concurrent faults), and pte mapped but not yet locked. 3265 * We return with mmap_sem still held, but pte unmapped and unlocked. 3266 */ 3267 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 3268 unsigned long address, pte_t *page_table, pmd_t *pmd, 3269 unsigned int flags) 3270 { 3271 struct page *page; 3272 spinlock_t *ptl; 3273 pte_t entry; 3274 3275 pte_unmap(page_table); 3276 3277 /* Check if we need to add a guard page to the stack */ 3278 if (check_stack_guard_page(vma, address) < 0) 3279 return VM_FAULT_SIGBUS; 3280 3281 /* Use the zero-page for reads */ 3282 if (!(flags & FAULT_FLAG_WRITE)) { 3283 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), 3284 vma->vm_page_prot)); 3285 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3286 if (!pte_none(*page_table)) 3287 goto unlock; 3288 goto setpte; 3289 } 3290 3291 /* Allocate our own private page. */ 3292 if (unlikely(anon_vma_prepare(vma))) 3293 goto oom; 3294 page = alloc_zeroed_user_highpage_movable(vma, address); 3295 if (!page) 3296 goto oom; 3297 /* 3298 * The memory barrier inside __SetPageUptodate makes sure that 3299 * preceeding stores to the page contents become visible before 3300 * the set_pte_at() write. 3301 */ 3302 __SetPageUptodate(page); 3303 3304 if (mem_cgroup_charge_anon(page, mm, GFP_KERNEL)) 3305 goto oom_free_page; 3306 3307 entry = mk_pte(page, vma->vm_page_prot); 3308 if (vma->vm_flags & VM_WRITE) 3309 entry = pte_mkwrite(pte_mkdirty(entry)); 3310 3311 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3312 if (!pte_none(*page_table)) 3313 goto release; 3314 3315 inc_mm_counter_fast(mm, MM_ANONPAGES); 3316 page_add_new_anon_rmap(page, vma, address); 3317 setpte: 3318 set_pte_at(mm, address, page_table, entry); 3319 3320 /* No need to invalidate - it was non-present before */ 3321 update_mmu_cache(vma, address, page_table); 3322 unlock: 3323 pte_unmap_unlock(page_table, ptl); 3324 return 0; 3325 release: 3326 mem_cgroup_uncharge_page(page); 3327 page_cache_release(page); 3328 goto unlock; 3329 oom_free_page: 3330 page_cache_release(page); 3331 oom: 3332 return VM_FAULT_OOM; 3333 } 3334 3335 static int __do_fault(struct vm_area_struct *vma, unsigned long address, 3336 pgoff_t pgoff, unsigned int flags, struct page **page) 3337 { 3338 struct vm_fault vmf; 3339 int ret; 3340 3341 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 3342 vmf.pgoff = pgoff; 3343 vmf.flags = flags; 3344 vmf.page = NULL; 3345 3346 ret = vma->vm_ops->fault(vma, &vmf); 3347 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3348 return ret; 3349 3350 if (unlikely(PageHWPoison(vmf.page))) { 3351 if (ret & VM_FAULT_LOCKED) 3352 unlock_page(vmf.page); 3353 page_cache_release(vmf.page); 3354 return VM_FAULT_HWPOISON; 3355 } 3356 3357 if (unlikely(!(ret & VM_FAULT_LOCKED))) 3358 lock_page(vmf.page); 3359 else 3360 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page); 3361 3362 *page = vmf.page; 3363 return ret; 3364 } 3365 3366 /** 3367 * do_set_pte - setup new PTE entry for given page and add reverse page mapping. 3368 * 3369 * @vma: virtual memory area 3370 * @address: user virtual address 3371 * @page: page to map 3372 * @pte: pointer to target page table entry 3373 * @write: true, if new entry is writable 3374 * @anon: true, if it's anonymous page 3375 * 3376 * Caller must hold page table lock relevant for @pte. 3377 * 3378 * Target users are page handler itself and implementations of 3379 * vm_ops->map_pages. 3380 */ 3381 void do_set_pte(struct vm_area_struct *vma, unsigned long address, 3382 struct page *page, pte_t *pte, bool write, bool anon) 3383 { 3384 pte_t entry; 3385 3386 flush_icache_page(vma, page); 3387 entry = mk_pte(page, vma->vm_page_prot); 3388 if (write) 3389 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3390 else if (pte_file(*pte) && pte_file_soft_dirty(*pte)) 3391 pte_mksoft_dirty(entry); 3392 if (anon) { 3393 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 3394 page_add_new_anon_rmap(page, vma, address); 3395 } else { 3396 inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES); 3397 page_add_file_rmap(page); 3398 } 3399 set_pte_at(vma->vm_mm, address, pte, entry); 3400 3401 /* no need to invalidate: a not-present page won't be cached */ 3402 update_mmu_cache(vma, address, pte); 3403 } 3404 3405 #define FAULT_AROUND_ORDER 4 3406 3407 #ifdef CONFIG_DEBUG_FS 3408 static unsigned int fault_around_order = FAULT_AROUND_ORDER; 3409 3410 static int fault_around_order_get(void *data, u64 *val) 3411 { 3412 *val = fault_around_order; 3413 return 0; 3414 } 3415 3416 static int fault_around_order_set(void *data, u64 val) 3417 { 3418 BUILD_BUG_ON((1UL << FAULT_AROUND_ORDER) > PTRS_PER_PTE); 3419 if (1UL << val > PTRS_PER_PTE) 3420 return -EINVAL; 3421 fault_around_order = val; 3422 return 0; 3423 } 3424 DEFINE_SIMPLE_ATTRIBUTE(fault_around_order_fops, 3425 fault_around_order_get, fault_around_order_set, "%llu\n"); 3426 3427 static int __init fault_around_debugfs(void) 3428 { 3429 void *ret; 3430 3431 ret = debugfs_create_file("fault_around_order", 0644, NULL, NULL, 3432 &fault_around_order_fops); 3433 if (!ret) 3434 pr_warn("Failed to create fault_around_order in debugfs"); 3435 return 0; 3436 } 3437 late_initcall(fault_around_debugfs); 3438 3439 static inline unsigned long fault_around_pages(void) 3440 { 3441 return 1UL << fault_around_order; 3442 } 3443 3444 static inline unsigned long fault_around_mask(void) 3445 { 3446 return ~((1UL << (PAGE_SHIFT + fault_around_order)) - 1); 3447 } 3448 #else 3449 static inline unsigned long fault_around_pages(void) 3450 { 3451 unsigned long nr_pages; 3452 3453 nr_pages = 1UL << FAULT_AROUND_ORDER; 3454 BUILD_BUG_ON(nr_pages > PTRS_PER_PTE); 3455 return nr_pages; 3456 } 3457 3458 static inline unsigned long fault_around_mask(void) 3459 { 3460 return ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1); 3461 } 3462 #endif 3463 3464 static void do_fault_around(struct vm_area_struct *vma, unsigned long address, 3465 pte_t *pte, pgoff_t pgoff, unsigned int flags) 3466 { 3467 unsigned long start_addr; 3468 pgoff_t max_pgoff; 3469 struct vm_fault vmf; 3470 int off; 3471 3472 start_addr = max(address & fault_around_mask(), vma->vm_start); 3473 off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); 3474 pte -= off; 3475 pgoff -= off; 3476 3477 /* 3478 * max_pgoff is either end of page table or end of vma 3479 * or fault_around_pages() from pgoff, depending what is neast. 3480 */ 3481 max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + 3482 PTRS_PER_PTE - 1; 3483 max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1, 3484 pgoff + fault_around_pages() - 1); 3485 3486 /* Check if it makes any sense to call ->map_pages */ 3487 while (!pte_none(*pte)) { 3488 if (++pgoff > max_pgoff) 3489 return; 3490 start_addr += PAGE_SIZE; 3491 if (start_addr >= vma->vm_end) 3492 return; 3493 pte++; 3494 } 3495 3496 vmf.virtual_address = (void __user *) start_addr; 3497 vmf.pte = pte; 3498 vmf.pgoff = pgoff; 3499 vmf.max_pgoff = max_pgoff; 3500 vmf.flags = flags; 3501 vma->vm_ops->map_pages(vma, &vmf); 3502 } 3503 3504 static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3505 unsigned long address, pmd_t *pmd, 3506 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 3507 { 3508 struct page *fault_page; 3509 spinlock_t *ptl; 3510 pte_t *pte; 3511 int ret = 0; 3512 3513 /* 3514 * Let's call ->map_pages() first and use ->fault() as fallback 3515 * if page by the offset is not ready to be mapped (cold cache or 3516 * something). 3517 */ 3518 if (vma->vm_ops->map_pages) { 3519 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 3520 do_fault_around(vma, address, pte, pgoff, flags); 3521 if (!pte_same(*pte, orig_pte)) 3522 goto unlock_out; 3523 pte_unmap_unlock(pte, ptl); 3524 } 3525 3526 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 3527 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3528 return ret; 3529 3530 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 3531 if (unlikely(!pte_same(*pte, orig_pte))) { 3532 pte_unmap_unlock(pte, ptl); 3533 unlock_page(fault_page); 3534 page_cache_release(fault_page); 3535 return ret; 3536 } 3537 do_set_pte(vma, address, fault_page, pte, false, false); 3538 unlock_page(fault_page); 3539 unlock_out: 3540 pte_unmap_unlock(pte, ptl); 3541 return ret; 3542 } 3543 3544 static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3545 unsigned long address, pmd_t *pmd, 3546 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 3547 { 3548 struct page *fault_page, *new_page; 3549 spinlock_t *ptl; 3550 pte_t *pte; 3551 int ret; 3552 3553 if (unlikely(anon_vma_prepare(vma))) 3554 return VM_FAULT_OOM; 3555 3556 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 3557 if (!new_page) 3558 return VM_FAULT_OOM; 3559 3560 if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) { 3561 page_cache_release(new_page); 3562 return VM_FAULT_OOM; 3563 } 3564 3565 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 3566 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3567 goto uncharge_out; 3568 3569 copy_user_highpage(new_page, fault_page, address, vma); 3570 __SetPageUptodate(new_page); 3571 3572 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 3573 if (unlikely(!pte_same(*pte, orig_pte))) { 3574 pte_unmap_unlock(pte, ptl); 3575 unlock_page(fault_page); 3576 page_cache_release(fault_page); 3577 goto uncharge_out; 3578 } 3579 do_set_pte(vma, address, new_page, pte, true, true); 3580 pte_unmap_unlock(pte, ptl); 3581 unlock_page(fault_page); 3582 page_cache_release(fault_page); 3583 return ret; 3584 uncharge_out: 3585 mem_cgroup_uncharge_page(new_page); 3586 page_cache_release(new_page); 3587 return ret; 3588 } 3589 3590 static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3591 unsigned long address, pmd_t *pmd, 3592 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 3593 { 3594 struct page *fault_page; 3595 struct address_space *mapping; 3596 spinlock_t *ptl; 3597 pte_t *pte; 3598 int dirtied = 0; 3599 int ret, tmp; 3600 3601 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 3602 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 3603 return ret; 3604 3605 /* 3606 * Check if the backing address space wants to know that the page is 3607 * about to become writable 3608 */ 3609 if (vma->vm_ops->page_mkwrite) { 3610 unlock_page(fault_page); 3611 tmp = do_page_mkwrite(vma, fault_page, address); 3612 if (unlikely(!tmp || 3613 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 3614 page_cache_release(fault_page); 3615 return tmp; 3616 } 3617 } 3618 3619 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 3620 if (unlikely(!pte_same(*pte, orig_pte))) { 3621 pte_unmap_unlock(pte, ptl); 3622 unlock_page(fault_page); 3623 page_cache_release(fault_page); 3624 return ret; 3625 } 3626 do_set_pte(vma, address, fault_page, pte, true, false); 3627 pte_unmap_unlock(pte, ptl); 3628 3629 if (set_page_dirty(fault_page)) 3630 dirtied = 1; 3631 mapping = fault_page->mapping; 3632 unlock_page(fault_page); 3633 if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) { 3634 /* 3635 * Some device drivers do not set page.mapping but still 3636 * dirty their pages 3637 */ 3638 balance_dirty_pages_ratelimited(mapping); 3639 } 3640 3641 /* file_update_time outside page_lock */ 3642 if (vma->vm_file && !vma->vm_ops->page_mkwrite) 3643 file_update_time(vma->vm_file); 3644 3645 return ret; 3646 } 3647 3648 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3649 unsigned long address, pte_t *page_table, pmd_t *pmd, 3650 unsigned int flags, pte_t orig_pte) 3651 { 3652 pgoff_t pgoff = (((address & PAGE_MASK) 3653 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 3654 3655 pte_unmap(page_table); 3656 if (!(flags & FAULT_FLAG_WRITE)) 3657 return do_read_fault(mm, vma, address, pmd, pgoff, flags, 3658 orig_pte); 3659 if (!(vma->vm_flags & VM_SHARED)) 3660 return do_cow_fault(mm, vma, address, pmd, pgoff, flags, 3661 orig_pte); 3662 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3663 } 3664 3665 /* 3666 * Fault of a previously existing named mapping. Repopulate the pte 3667 * from the encoded file_pte if possible. This enables swappable 3668 * nonlinear vmas. 3669 * 3670 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3671 * but allow concurrent faults), and pte mapped but not yet locked. 3672 * We return with mmap_sem still held, but pte unmapped and unlocked. 3673 */ 3674 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3675 unsigned long address, pte_t *page_table, pmd_t *pmd, 3676 unsigned int flags, pte_t orig_pte) 3677 { 3678 pgoff_t pgoff; 3679 3680 flags |= FAULT_FLAG_NONLINEAR; 3681 3682 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3683 return 0; 3684 3685 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 3686 /* 3687 * Page table corrupted: show pte and kill process. 3688 */ 3689 print_bad_pte(vma, address, orig_pte, NULL); 3690 return VM_FAULT_SIGBUS; 3691 } 3692 3693 pgoff = pte_to_pgoff(orig_pte); 3694 if (!(flags & FAULT_FLAG_WRITE)) 3695 return do_read_fault(mm, vma, address, pmd, pgoff, flags, 3696 orig_pte); 3697 if (!(vma->vm_flags & VM_SHARED)) 3698 return do_cow_fault(mm, vma, address, pmd, pgoff, flags, 3699 orig_pte); 3700 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3701 } 3702 3703 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, 3704 unsigned long addr, int page_nid, 3705 int *flags) 3706 { 3707 get_page(page); 3708 3709 count_vm_numa_event(NUMA_HINT_FAULTS); 3710 if (page_nid == numa_node_id()) { 3711 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 3712 *flags |= TNF_FAULT_LOCAL; 3713 } 3714 3715 return mpol_misplaced(page, vma, addr); 3716 } 3717 3718 static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 3719 unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd) 3720 { 3721 struct page *page = NULL; 3722 spinlock_t *ptl; 3723 int page_nid = -1; 3724 int last_cpupid; 3725 int target_nid; 3726 bool migrated = false; 3727 int flags = 0; 3728 3729 /* 3730 * The "pte" at this point cannot be used safely without 3731 * validation through pte_unmap_same(). It's of NUMA type but 3732 * the pfn may be screwed if the read is non atomic. 3733 * 3734 * ptep_modify_prot_start is not called as this is clearing 3735 * the _PAGE_NUMA bit and it is not really expected that there 3736 * would be concurrent hardware modifications to the PTE. 3737 */ 3738 ptl = pte_lockptr(mm, pmd); 3739 spin_lock(ptl); 3740 if (unlikely(!pte_same(*ptep, pte))) { 3741 pte_unmap_unlock(ptep, ptl); 3742 goto out; 3743 } 3744 3745 pte = pte_mknonnuma(pte); 3746 set_pte_at(mm, addr, ptep, pte); 3747 update_mmu_cache(vma, addr, ptep); 3748 3749 page = vm_normal_page(vma, addr, pte); 3750 if (!page) { 3751 pte_unmap_unlock(ptep, ptl); 3752 return 0; 3753 } 3754 BUG_ON(is_zero_pfn(page_to_pfn(page))); 3755 3756 /* 3757 * Avoid grouping on DSO/COW pages in specific and RO pages 3758 * in general, RO pages shouldn't hurt as much anyway since 3759 * they can be in shared cache state. 3760 */ 3761 if (!pte_write(pte)) 3762 flags |= TNF_NO_GROUP; 3763 3764 /* 3765 * Flag if the page is shared between multiple address spaces. This 3766 * is later used when determining whether to group tasks together 3767 */ 3768 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) 3769 flags |= TNF_SHARED; 3770 3771 last_cpupid = page_cpupid_last(page); 3772 page_nid = page_to_nid(page); 3773 target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags); 3774 pte_unmap_unlock(ptep, ptl); 3775 if (target_nid == -1) { 3776 put_page(page); 3777 goto out; 3778 } 3779 3780 /* Migrate to the requested node */ 3781 migrated = migrate_misplaced_page(page, vma, target_nid); 3782 if (migrated) { 3783 page_nid = target_nid; 3784 flags |= TNF_MIGRATED; 3785 } 3786 3787 out: 3788 if (page_nid != -1) 3789 task_numa_fault(last_cpupid, page_nid, 1, flags); 3790 return 0; 3791 } 3792 3793 /* 3794 * These routines also need to handle stuff like marking pages dirty 3795 * and/or accessed for architectures that don't do it in hardware (most 3796 * RISC architectures). The early dirtying is also good on the i386. 3797 * 3798 * There is also a hook called "update_mmu_cache()" that architectures 3799 * with external mmu caches can use to update those (ie the Sparc or 3800 * PowerPC hashed page tables that act as extended TLBs). 3801 * 3802 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3803 * but allow concurrent faults), and pte mapped but not yet locked. 3804 * We return with mmap_sem still held, but pte unmapped and unlocked. 3805 */ 3806 static int handle_pte_fault(struct mm_struct *mm, 3807 struct vm_area_struct *vma, unsigned long address, 3808 pte_t *pte, pmd_t *pmd, unsigned int flags) 3809 { 3810 pte_t entry; 3811 spinlock_t *ptl; 3812 3813 entry = *pte; 3814 if (!pte_present(entry)) { 3815 if (pte_none(entry)) { 3816 if (vma->vm_ops) { 3817 if (likely(vma->vm_ops->fault)) 3818 return do_linear_fault(mm, vma, address, 3819 pte, pmd, flags, entry); 3820 } 3821 return do_anonymous_page(mm, vma, address, 3822 pte, pmd, flags); 3823 } 3824 if (pte_file(entry)) 3825 return do_nonlinear_fault(mm, vma, address, 3826 pte, pmd, flags, entry); 3827 return do_swap_page(mm, vma, address, 3828 pte, pmd, flags, entry); 3829 } 3830 3831 if (pte_numa(entry)) 3832 return do_numa_page(mm, vma, address, entry, pte, pmd); 3833 3834 ptl = pte_lockptr(mm, pmd); 3835 spin_lock(ptl); 3836 if (unlikely(!pte_same(*pte, entry))) 3837 goto unlock; 3838 if (flags & FAULT_FLAG_WRITE) { 3839 if (!pte_write(entry)) 3840 return do_wp_page(mm, vma, address, 3841 pte, pmd, ptl, entry); 3842 entry = pte_mkdirty(entry); 3843 } 3844 entry = pte_mkyoung(entry); 3845 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 3846 update_mmu_cache(vma, address, pte); 3847 } else { 3848 /* 3849 * This is needed only for protection faults but the arch code 3850 * is not yet telling us if this is a protection fault or not. 3851 * This still avoids useless tlb flushes for .text page faults 3852 * with threads. 3853 */ 3854 if (flags & FAULT_FLAG_WRITE) 3855 flush_tlb_fix_spurious_fault(vma, address); 3856 } 3857 unlock: 3858 pte_unmap_unlock(pte, ptl); 3859 return 0; 3860 } 3861 3862 /* 3863 * By the time we get here, we already hold the mm semaphore 3864 */ 3865 static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3866 unsigned long address, unsigned int flags) 3867 { 3868 pgd_t *pgd; 3869 pud_t *pud; 3870 pmd_t *pmd; 3871 pte_t *pte; 3872 3873 if (unlikely(is_vm_hugetlb_page(vma))) 3874 return hugetlb_fault(mm, vma, address, flags); 3875 3876 pgd = pgd_offset(mm, address); 3877 pud = pud_alloc(mm, pgd, address); 3878 if (!pud) 3879 return VM_FAULT_OOM; 3880 pmd = pmd_alloc(mm, pud, address); 3881 if (!pmd) 3882 return VM_FAULT_OOM; 3883 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { 3884 int ret = VM_FAULT_FALLBACK; 3885 if (!vma->vm_ops) 3886 ret = do_huge_pmd_anonymous_page(mm, vma, address, 3887 pmd, flags); 3888 if (!(ret & VM_FAULT_FALLBACK)) 3889 return ret; 3890 } else { 3891 pmd_t orig_pmd = *pmd; 3892 int ret; 3893 3894 barrier(); 3895 if (pmd_trans_huge(orig_pmd)) { 3896 unsigned int dirty = flags & FAULT_FLAG_WRITE; 3897 3898 /* 3899 * If the pmd is splitting, return and retry the 3900 * the fault. Alternative: wait until the split 3901 * is done, and goto retry. 3902 */ 3903 if (pmd_trans_splitting(orig_pmd)) 3904 return 0; 3905 3906 if (pmd_numa(orig_pmd)) 3907 return do_huge_pmd_numa_page(mm, vma, address, 3908 orig_pmd, pmd); 3909 3910 if (dirty && !pmd_write(orig_pmd)) { 3911 ret = do_huge_pmd_wp_page(mm, vma, address, pmd, 3912 orig_pmd); 3913 if (!(ret & VM_FAULT_FALLBACK)) 3914 return ret; 3915 } else { 3916 huge_pmd_set_accessed(mm, vma, address, pmd, 3917 orig_pmd, dirty); 3918 return 0; 3919 } 3920 } 3921 } 3922 3923 /* THP should already have been handled */ 3924 BUG_ON(pmd_numa(*pmd)); 3925 3926 /* 3927 * Use __pte_alloc instead of pte_alloc_map, because we can't 3928 * run pte_offset_map on the pmd, if an huge pmd could 3929 * materialize from under us from a different thread. 3930 */ 3931 if (unlikely(pmd_none(*pmd)) && 3932 unlikely(__pte_alloc(mm, vma, pmd, address))) 3933 return VM_FAULT_OOM; 3934 /* if an huge pmd materialized from under us just retry later */ 3935 if (unlikely(pmd_trans_huge(*pmd))) 3936 return 0; 3937 /* 3938 * A regular pmd is established and it can't morph into a huge pmd 3939 * from under us anymore at this point because we hold the mmap_sem 3940 * read mode and khugepaged takes it in write mode. So now it's 3941 * safe to run pte_offset_map(). 3942 */ 3943 pte = pte_offset_map(pmd, address); 3944 3945 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 3946 } 3947 3948 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3949 unsigned long address, unsigned int flags) 3950 { 3951 int ret; 3952 3953 __set_current_state(TASK_RUNNING); 3954 3955 count_vm_event(PGFAULT); 3956 mem_cgroup_count_vm_event(mm, PGFAULT); 3957 3958 /* do counter updates before entering really critical section. */ 3959 check_sync_rss_stat(current); 3960 3961 /* 3962 * Enable the memcg OOM handling for faults triggered in user 3963 * space. Kernel faults are handled more gracefully. 3964 */ 3965 if (flags & FAULT_FLAG_USER) 3966 mem_cgroup_oom_enable(); 3967 3968 ret = __handle_mm_fault(mm, vma, address, flags); 3969 3970 if (flags & FAULT_FLAG_USER) { 3971 mem_cgroup_oom_disable(); 3972 /* 3973 * The task may have entered a memcg OOM situation but 3974 * if the allocation error was handled gracefully (no 3975 * VM_FAULT_OOM), there is no need to kill anything. 3976 * Just clean up the OOM state peacefully. 3977 */ 3978 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) 3979 mem_cgroup_oom_synchronize(false); 3980 } 3981 3982 return ret; 3983 } 3984 3985 #ifndef __PAGETABLE_PUD_FOLDED 3986 /* 3987 * Allocate page upper directory. 3988 * We've already handled the fast-path in-line. 3989 */ 3990 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3991 { 3992 pud_t *new = pud_alloc_one(mm, address); 3993 if (!new) 3994 return -ENOMEM; 3995 3996 smp_wmb(); /* See comment in __pte_alloc */ 3997 3998 spin_lock(&mm->page_table_lock); 3999 if (pgd_present(*pgd)) /* Another has populated it */ 4000 pud_free(mm, new); 4001 else 4002 pgd_populate(mm, pgd, new); 4003 spin_unlock(&mm->page_table_lock); 4004 return 0; 4005 } 4006 #endif /* __PAGETABLE_PUD_FOLDED */ 4007 4008 #ifndef __PAGETABLE_PMD_FOLDED 4009 /* 4010 * Allocate page middle directory. 4011 * We've already handled the fast-path in-line. 4012 */ 4013 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 4014 { 4015 pmd_t *new = pmd_alloc_one(mm, address); 4016 if (!new) 4017 return -ENOMEM; 4018 4019 smp_wmb(); /* See comment in __pte_alloc */ 4020 4021 spin_lock(&mm->page_table_lock); 4022 #ifndef __ARCH_HAS_4LEVEL_HACK 4023 if (pud_present(*pud)) /* Another has populated it */ 4024 pmd_free(mm, new); 4025 else 4026 pud_populate(mm, pud, new); 4027 #else 4028 if (pgd_present(*pud)) /* Another has populated it */ 4029 pmd_free(mm, new); 4030 else 4031 pgd_populate(mm, pud, new); 4032 #endif /* __ARCH_HAS_4LEVEL_HACK */ 4033 spin_unlock(&mm->page_table_lock); 4034 return 0; 4035 } 4036 #endif /* __PAGETABLE_PMD_FOLDED */ 4037 4038 #if !defined(__HAVE_ARCH_GATE_AREA) 4039 4040 #if defined(AT_SYSINFO_EHDR) 4041 static struct vm_area_struct gate_vma; 4042 4043 static int __init gate_vma_init(void) 4044 { 4045 gate_vma.vm_mm = NULL; 4046 gate_vma.vm_start = FIXADDR_USER_START; 4047 gate_vma.vm_end = FIXADDR_USER_END; 4048 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 4049 gate_vma.vm_page_prot = __P101; 4050 4051 return 0; 4052 } 4053 __initcall(gate_vma_init); 4054 #endif 4055 4056 struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 4057 { 4058 #ifdef AT_SYSINFO_EHDR 4059 return &gate_vma; 4060 #else 4061 return NULL; 4062 #endif 4063 } 4064 4065 int in_gate_area_no_mm(unsigned long addr) 4066 { 4067 #ifdef AT_SYSINFO_EHDR 4068 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 4069 return 1; 4070 #endif 4071 return 0; 4072 } 4073 4074 #endif /* __HAVE_ARCH_GATE_AREA */ 4075 4076 static int __follow_pte(struct mm_struct *mm, unsigned long address, 4077 pte_t **ptepp, spinlock_t **ptlp) 4078 { 4079 pgd_t *pgd; 4080 pud_t *pud; 4081 pmd_t *pmd; 4082 pte_t *ptep; 4083 4084 pgd = pgd_offset(mm, address); 4085 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 4086 goto out; 4087 4088 pud = pud_offset(pgd, address); 4089 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 4090 goto out; 4091 4092 pmd = pmd_offset(pud, address); 4093 VM_BUG_ON(pmd_trans_huge(*pmd)); 4094 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 4095 goto out; 4096 4097 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 4098 if (pmd_huge(*pmd)) 4099 goto out; 4100 4101 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 4102 if (!ptep) 4103 goto out; 4104 if (!pte_present(*ptep)) 4105 goto unlock; 4106 *ptepp = ptep; 4107 return 0; 4108 unlock: 4109 pte_unmap_unlock(ptep, *ptlp); 4110 out: 4111 return -EINVAL; 4112 } 4113 4114 static inline int follow_pte(struct mm_struct *mm, unsigned long address, 4115 pte_t **ptepp, spinlock_t **ptlp) 4116 { 4117 int res; 4118 4119 /* (void) is needed to make gcc happy */ 4120 (void) __cond_lock(*ptlp, 4121 !(res = __follow_pte(mm, address, ptepp, ptlp))); 4122 return res; 4123 } 4124 4125 /** 4126 * follow_pfn - look up PFN at a user virtual address 4127 * @vma: memory mapping 4128 * @address: user virtual address 4129 * @pfn: location to store found PFN 4130 * 4131 * Only IO mappings and raw PFN mappings are allowed. 4132 * 4133 * Returns zero and the pfn at @pfn on success, -ve otherwise. 4134 */ 4135 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 4136 unsigned long *pfn) 4137 { 4138 int ret = -EINVAL; 4139 spinlock_t *ptl; 4140 pte_t *ptep; 4141 4142 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4143 return ret; 4144 4145 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 4146 if (ret) 4147 return ret; 4148 *pfn = pte_pfn(*ptep); 4149 pte_unmap_unlock(ptep, ptl); 4150 return 0; 4151 } 4152 EXPORT_SYMBOL(follow_pfn); 4153 4154 #ifdef CONFIG_HAVE_IOREMAP_PROT 4155 int follow_phys(struct vm_area_struct *vma, 4156 unsigned long address, unsigned int flags, 4157 unsigned long *prot, resource_size_t *phys) 4158 { 4159 int ret = -EINVAL; 4160 pte_t *ptep, pte; 4161 spinlock_t *ptl; 4162 4163 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4164 goto out; 4165 4166 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 4167 goto out; 4168 pte = *ptep; 4169 4170 if ((flags & FOLL_WRITE) && !pte_write(pte)) 4171 goto unlock; 4172 4173 *prot = pgprot_val(pte_pgprot(pte)); 4174 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 4175 4176 ret = 0; 4177 unlock: 4178 pte_unmap_unlock(ptep, ptl); 4179 out: 4180 return ret; 4181 } 4182 4183 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 4184 void *buf, int len, int write) 4185 { 4186 resource_size_t phys_addr; 4187 unsigned long prot = 0; 4188 void __iomem *maddr; 4189 int offset = addr & (PAGE_SIZE-1); 4190 4191 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 4192 return -EINVAL; 4193 4194 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 4195 if (write) 4196 memcpy_toio(maddr + offset, buf, len); 4197 else 4198 memcpy_fromio(buf, maddr + offset, len); 4199 iounmap(maddr); 4200 4201 return len; 4202 } 4203 EXPORT_SYMBOL_GPL(generic_access_phys); 4204 #endif 4205 4206 /* 4207 * Access another process' address space as given in mm. If non-NULL, use the 4208 * given task for page fault accounting. 4209 */ 4210 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 4211 unsigned long addr, void *buf, int len, int write) 4212 { 4213 struct vm_area_struct *vma; 4214 void *old_buf = buf; 4215 4216 down_read(&mm->mmap_sem); 4217 /* ignore errors, just check how much was successfully transferred */ 4218 while (len) { 4219 int bytes, ret, offset; 4220 void *maddr; 4221 struct page *page = NULL; 4222 4223 ret = get_user_pages(tsk, mm, addr, 1, 4224 write, 1, &page, &vma); 4225 if (ret <= 0) { 4226 /* 4227 * Check if this is a VM_IO | VM_PFNMAP VMA, which 4228 * we can access using slightly different code. 4229 */ 4230 #ifdef CONFIG_HAVE_IOREMAP_PROT 4231 vma = find_vma(mm, addr); 4232 if (!vma || vma->vm_start > addr) 4233 break; 4234 if (vma->vm_ops && vma->vm_ops->access) 4235 ret = vma->vm_ops->access(vma, addr, buf, 4236 len, write); 4237 if (ret <= 0) 4238 #endif 4239 break; 4240 bytes = ret; 4241 } else { 4242 bytes = len; 4243 offset = addr & (PAGE_SIZE-1); 4244 if (bytes > PAGE_SIZE-offset) 4245 bytes = PAGE_SIZE-offset; 4246 4247 maddr = kmap(page); 4248 if (write) { 4249 copy_to_user_page(vma, page, addr, 4250 maddr + offset, buf, bytes); 4251 set_page_dirty_lock(page); 4252 } else { 4253 copy_from_user_page(vma, page, addr, 4254 buf, maddr + offset, bytes); 4255 } 4256 kunmap(page); 4257 page_cache_release(page); 4258 } 4259 len -= bytes; 4260 buf += bytes; 4261 addr += bytes; 4262 } 4263 up_read(&mm->mmap_sem); 4264 4265 return buf - old_buf; 4266 } 4267 4268 /** 4269 * access_remote_vm - access another process' address space 4270 * @mm: the mm_struct of the target address space 4271 * @addr: start address to access 4272 * @buf: source or destination buffer 4273 * @len: number of bytes to transfer 4274 * @write: whether the access is a write 4275 * 4276 * The caller must hold a reference on @mm. 4277 */ 4278 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 4279 void *buf, int len, int write) 4280 { 4281 return __access_remote_vm(NULL, mm, addr, buf, len, write); 4282 } 4283 4284 /* 4285 * Access another process' address space. 4286 * Source/target buffer must be kernel space, 4287 * Do not walk the page table directly, use get_user_pages 4288 */ 4289 int access_process_vm(struct task_struct *tsk, unsigned long addr, 4290 void *buf, int len, int write) 4291 { 4292 struct mm_struct *mm; 4293 int ret; 4294 4295 mm = get_task_mm(tsk); 4296 if (!mm) 4297 return 0; 4298 4299 ret = __access_remote_vm(tsk, mm, addr, buf, len, write); 4300 mmput(mm); 4301 4302 return ret; 4303 } 4304 4305 /* 4306 * Print the name of a VMA. 4307 */ 4308 void print_vma_addr(char *prefix, unsigned long ip) 4309 { 4310 struct mm_struct *mm = current->mm; 4311 struct vm_area_struct *vma; 4312 4313 /* 4314 * Do not print if we are in atomic 4315 * contexts (in exception stacks, etc.): 4316 */ 4317 if (preempt_count()) 4318 return; 4319 4320 down_read(&mm->mmap_sem); 4321 vma = find_vma(mm, ip); 4322 if (vma && vma->vm_file) { 4323 struct file *f = vma->vm_file; 4324 char *buf = (char *)__get_free_page(GFP_KERNEL); 4325 if (buf) { 4326 char *p; 4327 4328 p = d_path(&f->f_path, buf, PAGE_SIZE); 4329 if (IS_ERR(p)) 4330 p = "?"; 4331 printk("%s%s[%lx+%lx]", prefix, kbasename(p), 4332 vma->vm_start, 4333 vma->vm_end - vma->vm_start); 4334 free_page((unsigned long)buf); 4335 } 4336 } 4337 up_read(&mm->mmap_sem); 4338 } 4339 4340 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) 4341 void might_fault(void) 4342 { 4343 /* 4344 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 4345 * holding the mmap_sem, this is safe because kernel memory doesn't 4346 * get paged out, therefore we'll never actually fault, and the 4347 * below annotations will generate false positives. 4348 */ 4349 if (segment_eq(get_fs(), KERNEL_DS)) 4350 return; 4351 4352 /* 4353 * it would be nicer only to annotate paths which are not under 4354 * pagefault_disable, however that requires a larger audit and 4355 * providing helpers like get_user_atomic. 4356 */ 4357 if (in_atomic()) 4358 return; 4359 4360 __might_sleep(__FILE__, __LINE__, 0); 4361 4362 if (current->mm) 4363 might_lock_read(¤t->mm->mmap_sem); 4364 } 4365 EXPORT_SYMBOL(might_fault); 4366 #endif 4367 4368 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 4369 static void clear_gigantic_page(struct page *page, 4370 unsigned long addr, 4371 unsigned int pages_per_huge_page) 4372 { 4373 int i; 4374 struct page *p = page; 4375 4376 might_sleep(); 4377 for (i = 0; i < pages_per_huge_page; 4378 i++, p = mem_map_next(p, page, i)) { 4379 cond_resched(); 4380 clear_user_highpage(p, addr + i * PAGE_SIZE); 4381 } 4382 } 4383 void clear_huge_page(struct page *page, 4384 unsigned long addr, unsigned int pages_per_huge_page) 4385 { 4386 int i; 4387 4388 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4389 clear_gigantic_page(page, addr, pages_per_huge_page); 4390 return; 4391 } 4392 4393 might_sleep(); 4394 for (i = 0; i < pages_per_huge_page; i++) { 4395 cond_resched(); 4396 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 4397 } 4398 } 4399 4400 static void copy_user_gigantic_page(struct page *dst, struct page *src, 4401 unsigned long addr, 4402 struct vm_area_struct *vma, 4403 unsigned int pages_per_huge_page) 4404 { 4405 int i; 4406 struct page *dst_base = dst; 4407 struct page *src_base = src; 4408 4409 for (i = 0; i < pages_per_huge_page; ) { 4410 cond_resched(); 4411 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 4412 4413 i++; 4414 dst = mem_map_next(dst, dst_base, i); 4415 src = mem_map_next(src, src_base, i); 4416 } 4417 } 4418 4419 void copy_user_huge_page(struct page *dst, struct page *src, 4420 unsigned long addr, struct vm_area_struct *vma, 4421 unsigned int pages_per_huge_page) 4422 { 4423 int i; 4424 4425 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4426 copy_user_gigantic_page(dst, src, addr, vma, 4427 pages_per_huge_page); 4428 return; 4429 } 4430 4431 might_sleep(); 4432 for (i = 0; i < pages_per_huge_page; i++) { 4433 cond_resched(); 4434 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 4435 } 4436 } 4437 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 4438 4439 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS 4440 4441 static struct kmem_cache *page_ptl_cachep; 4442 4443 void __init ptlock_cache_init(void) 4444 { 4445 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, 4446 SLAB_PANIC, NULL); 4447 } 4448 4449 bool ptlock_alloc(struct page *page) 4450 { 4451 spinlock_t *ptl; 4452 4453 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); 4454 if (!ptl) 4455 return false; 4456 page->ptl = ptl; 4457 return true; 4458 } 4459 4460 void ptlock_free(struct page *page) 4461 { 4462 kmem_cache_free(page_ptl_cachep, page->ptl); 4463 } 4464 #endif 4465