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 61 #include <asm/io.h> 62 #include <asm/pgalloc.h> 63 #include <asm/uaccess.h> 64 #include <asm/tlb.h> 65 #include <asm/tlbflush.h> 66 #include <asm/pgtable.h> 67 68 #include "internal.h" 69 70 #ifndef CONFIG_NEED_MULTIPLE_NODES 71 /* use the per-pgdat data instead for discontigmem - mbligh */ 72 unsigned long max_mapnr; 73 struct page *mem_map; 74 75 EXPORT_SYMBOL(max_mapnr); 76 EXPORT_SYMBOL(mem_map); 77 #endif 78 79 unsigned long num_physpages; 80 /* 81 * A number of key systems in x86 including ioremap() rely on the assumption 82 * that high_memory defines the upper bound on direct map memory, then end 83 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 84 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 85 * and ZONE_HIGHMEM. 86 */ 87 void * high_memory; 88 89 EXPORT_SYMBOL(num_physpages); 90 EXPORT_SYMBOL(high_memory); 91 92 /* 93 * Randomize the address space (stacks, mmaps, brk, etc.). 94 * 95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 96 * as ancient (libc5 based) binaries can segfault. ) 97 */ 98 int randomize_va_space __read_mostly = 99 #ifdef CONFIG_COMPAT_BRK 100 1; 101 #else 102 2; 103 #endif 104 105 static int __init disable_randmaps(char *s) 106 { 107 randomize_va_space = 0; 108 return 1; 109 } 110 __setup("norandmaps", disable_randmaps); 111 112 unsigned long zero_pfn __read_mostly; 113 unsigned long highest_memmap_pfn __read_mostly; 114 115 /* 116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 117 */ 118 static int __init init_zero_pfn(void) 119 { 120 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 121 return 0; 122 } 123 core_initcall(init_zero_pfn); 124 125 126 #if defined(SPLIT_RSS_COUNTING) 127 128 void sync_mm_rss(struct mm_struct *mm) 129 { 130 int i; 131 132 for (i = 0; i < NR_MM_COUNTERS; i++) { 133 if (current->rss_stat.count[i]) { 134 add_mm_counter(mm, i, current->rss_stat.count[i]); 135 current->rss_stat.count[i] = 0; 136 } 137 } 138 current->rss_stat.events = 0; 139 } 140 141 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 142 { 143 struct task_struct *task = current; 144 145 if (likely(task->mm == mm)) 146 task->rss_stat.count[member] += val; 147 else 148 add_mm_counter(mm, member, val); 149 } 150 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 151 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 152 153 /* sync counter once per 64 page faults */ 154 #define TASK_RSS_EVENTS_THRESH (64) 155 static void check_sync_rss_stat(struct task_struct *task) 156 { 157 if (unlikely(task != current)) 158 return; 159 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 160 sync_mm_rss(task->mm); 161 } 162 #else /* SPLIT_RSS_COUNTING */ 163 164 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 165 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 166 167 static void check_sync_rss_stat(struct task_struct *task) 168 { 169 } 170 171 #endif /* SPLIT_RSS_COUNTING */ 172 173 #ifdef HAVE_GENERIC_MMU_GATHER 174 175 static int tlb_next_batch(struct mmu_gather *tlb) 176 { 177 struct mmu_gather_batch *batch; 178 179 batch = tlb->active; 180 if (batch->next) { 181 tlb->active = batch->next; 182 return 1; 183 } 184 185 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 186 if (!batch) 187 return 0; 188 189 batch->next = NULL; 190 batch->nr = 0; 191 batch->max = MAX_GATHER_BATCH; 192 193 tlb->active->next = batch; 194 tlb->active = batch; 195 196 return 1; 197 } 198 199 /* tlb_gather_mmu 200 * Called to initialize an (on-stack) mmu_gather structure for page-table 201 * tear-down from @mm. The @fullmm argument is used when @mm is without 202 * users and we're going to destroy the full address space (exit/execve). 203 */ 204 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm) 205 { 206 tlb->mm = mm; 207 208 tlb->fullmm = fullmm; 209 tlb->need_flush = 0; 210 tlb->fast_mode = (num_possible_cpus() == 1); 211 tlb->local.next = NULL; 212 tlb->local.nr = 0; 213 tlb->local.max = ARRAY_SIZE(tlb->__pages); 214 tlb->active = &tlb->local; 215 216 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 217 tlb->batch = NULL; 218 #endif 219 } 220 221 void tlb_flush_mmu(struct mmu_gather *tlb) 222 { 223 struct mmu_gather_batch *batch; 224 225 if (!tlb->need_flush) 226 return; 227 tlb->need_flush = 0; 228 tlb_flush(tlb); 229 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 230 tlb_table_flush(tlb); 231 #endif 232 233 if (tlb_fast_mode(tlb)) 234 return; 235 236 for (batch = &tlb->local; batch; batch = batch->next) { 237 free_pages_and_swap_cache(batch->pages, batch->nr); 238 batch->nr = 0; 239 } 240 tlb->active = &tlb->local; 241 } 242 243 /* tlb_finish_mmu 244 * Called at the end of the shootdown operation to free up any resources 245 * that were required. 246 */ 247 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 248 { 249 struct mmu_gather_batch *batch, *next; 250 251 tlb_flush_mmu(tlb); 252 253 /* keep the page table cache within bounds */ 254 check_pgt_cache(); 255 256 for (batch = tlb->local.next; batch; batch = next) { 257 next = batch->next; 258 free_pages((unsigned long)batch, 0); 259 } 260 tlb->local.next = NULL; 261 } 262 263 /* __tlb_remove_page 264 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 265 * handling the additional races in SMP caused by other CPUs caching valid 266 * mappings in their TLBs. Returns the number of free page slots left. 267 * When out of page slots we must call tlb_flush_mmu(). 268 */ 269 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) 270 { 271 struct mmu_gather_batch *batch; 272 273 VM_BUG_ON(!tlb->need_flush); 274 275 if (tlb_fast_mode(tlb)) { 276 free_page_and_swap_cache(page); 277 return 1; /* avoid calling tlb_flush_mmu() */ 278 } 279 280 batch = tlb->active; 281 batch->pages[batch->nr++] = page; 282 if (batch->nr == batch->max) { 283 if (!tlb_next_batch(tlb)) 284 return 0; 285 batch = tlb->active; 286 } 287 VM_BUG_ON(batch->nr > batch->max); 288 289 return batch->max - batch->nr; 290 } 291 292 #endif /* HAVE_GENERIC_MMU_GATHER */ 293 294 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 295 296 /* 297 * See the comment near struct mmu_table_batch. 298 */ 299 300 static void tlb_remove_table_smp_sync(void *arg) 301 { 302 /* Simply deliver the interrupt */ 303 } 304 305 static void tlb_remove_table_one(void *table) 306 { 307 /* 308 * This isn't an RCU grace period and hence the page-tables cannot be 309 * assumed to be actually RCU-freed. 310 * 311 * It is however sufficient for software page-table walkers that rely on 312 * IRQ disabling. See the comment near struct mmu_table_batch. 313 */ 314 smp_call_function(tlb_remove_table_smp_sync, NULL, 1); 315 __tlb_remove_table(table); 316 } 317 318 static void tlb_remove_table_rcu(struct rcu_head *head) 319 { 320 struct mmu_table_batch *batch; 321 int i; 322 323 batch = container_of(head, struct mmu_table_batch, rcu); 324 325 for (i = 0; i < batch->nr; i++) 326 __tlb_remove_table(batch->tables[i]); 327 328 free_page((unsigned long)batch); 329 } 330 331 void tlb_table_flush(struct mmu_gather *tlb) 332 { 333 struct mmu_table_batch **batch = &tlb->batch; 334 335 if (*batch) { 336 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); 337 *batch = NULL; 338 } 339 } 340 341 void tlb_remove_table(struct mmu_gather *tlb, void *table) 342 { 343 struct mmu_table_batch **batch = &tlb->batch; 344 345 tlb->need_flush = 1; 346 347 /* 348 * When there's less then two users of this mm there cannot be a 349 * concurrent page-table walk. 350 */ 351 if (atomic_read(&tlb->mm->mm_users) < 2) { 352 __tlb_remove_table(table); 353 return; 354 } 355 356 if (*batch == NULL) { 357 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); 358 if (*batch == NULL) { 359 tlb_remove_table_one(table); 360 return; 361 } 362 (*batch)->nr = 0; 363 } 364 (*batch)->tables[(*batch)->nr++] = table; 365 if ((*batch)->nr == MAX_TABLE_BATCH) 366 tlb_table_flush(tlb); 367 } 368 369 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ 370 371 /* 372 * If a p?d_bad entry is found while walking page tables, report 373 * the error, before resetting entry to p?d_none. Usually (but 374 * very seldom) called out from the p?d_none_or_clear_bad macros. 375 */ 376 377 void pgd_clear_bad(pgd_t *pgd) 378 { 379 pgd_ERROR(*pgd); 380 pgd_clear(pgd); 381 } 382 383 void pud_clear_bad(pud_t *pud) 384 { 385 pud_ERROR(*pud); 386 pud_clear(pud); 387 } 388 389 void pmd_clear_bad(pmd_t *pmd) 390 { 391 pmd_ERROR(*pmd); 392 pmd_clear(pmd); 393 } 394 395 /* 396 * Note: this doesn't free the actual pages themselves. That 397 * has been handled earlier when unmapping all the memory regions. 398 */ 399 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 400 unsigned long addr) 401 { 402 pgtable_t token = pmd_pgtable(*pmd); 403 pmd_clear(pmd); 404 pte_free_tlb(tlb, token, addr); 405 tlb->mm->nr_ptes--; 406 } 407 408 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 409 unsigned long addr, unsigned long end, 410 unsigned long floor, unsigned long ceiling) 411 { 412 pmd_t *pmd; 413 unsigned long next; 414 unsigned long start; 415 416 start = addr; 417 pmd = pmd_offset(pud, addr); 418 do { 419 next = pmd_addr_end(addr, end); 420 if (pmd_none_or_clear_bad(pmd)) 421 continue; 422 free_pte_range(tlb, pmd, addr); 423 } while (pmd++, addr = next, addr != end); 424 425 start &= PUD_MASK; 426 if (start < floor) 427 return; 428 if (ceiling) { 429 ceiling &= PUD_MASK; 430 if (!ceiling) 431 return; 432 } 433 if (end - 1 > ceiling - 1) 434 return; 435 436 pmd = pmd_offset(pud, start); 437 pud_clear(pud); 438 pmd_free_tlb(tlb, pmd, start); 439 } 440 441 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 442 unsigned long addr, unsigned long end, 443 unsigned long floor, unsigned long ceiling) 444 { 445 pud_t *pud; 446 unsigned long next; 447 unsigned long start; 448 449 start = addr; 450 pud = pud_offset(pgd, addr); 451 do { 452 next = pud_addr_end(addr, end); 453 if (pud_none_or_clear_bad(pud)) 454 continue; 455 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 456 } while (pud++, addr = next, addr != end); 457 458 start &= PGDIR_MASK; 459 if (start < floor) 460 return; 461 if (ceiling) { 462 ceiling &= PGDIR_MASK; 463 if (!ceiling) 464 return; 465 } 466 if (end - 1 > ceiling - 1) 467 return; 468 469 pud = pud_offset(pgd, start); 470 pgd_clear(pgd); 471 pud_free_tlb(tlb, pud, start); 472 } 473 474 /* 475 * This function frees user-level page tables of a process. 476 * 477 * Must be called with pagetable lock held. 478 */ 479 void free_pgd_range(struct mmu_gather *tlb, 480 unsigned long addr, unsigned long end, 481 unsigned long floor, unsigned long ceiling) 482 { 483 pgd_t *pgd; 484 unsigned long next; 485 486 /* 487 * The next few lines have given us lots of grief... 488 * 489 * Why are we testing PMD* at this top level? Because often 490 * there will be no work to do at all, and we'd prefer not to 491 * go all the way down to the bottom just to discover that. 492 * 493 * Why all these "- 1"s? Because 0 represents both the bottom 494 * of the address space and the top of it (using -1 for the 495 * top wouldn't help much: the masks would do the wrong thing). 496 * The rule is that addr 0 and floor 0 refer to the bottom of 497 * the address space, but end 0 and ceiling 0 refer to the top 498 * Comparisons need to use "end - 1" and "ceiling - 1" (though 499 * that end 0 case should be mythical). 500 * 501 * Wherever addr is brought up or ceiling brought down, we must 502 * be careful to reject "the opposite 0" before it confuses the 503 * subsequent tests. But what about where end is brought down 504 * by PMD_SIZE below? no, end can't go down to 0 there. 505 * 506 * Whereas we round start (addr) and ceiling down, by different 507 * masks at different levels, in order to test whether a table 508 * now has no other vmas using it, so can be freed, we don't 509 * bother to round floor or end up - the tests don't need that. 510 */ 511 512 addr &= PMD_MASK; 513 if (addr < floor) { 514 addr += PMD_SIZE; 515 if (!addr) 516 return; 517 } 518 if (ceiling) { 519 ceiling &= PMD_MASK; 520 if (!ceiling) 521 return; 522 } 523 if (end - 1 > ceiling - 1) 524 end -= PMD_SIZE; 525 if (addr > end - 1) 526 return; 527 528 pgd = pgd_offset(tlb->mm, addr); 529 do { 530 next = pgd_addr_end(addr, end); 531 if (pgd_none_or_clear_bad(pgd)) 532 continue; 533 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 534 } while (pgd++, addr = next, addr != end); 535 } 536 537 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 538 unsigned long floor, unsigned long ceiling) 539 { 540 while (vma) { 541 struct vm_area_struct *next = vma->vm_next; 542 unsigned long addr = vma->vm_start; 543 544 /* 545 * Hide vma from rmap and truncate_pagecache before freeing 546 * pgtables 547 */ 548 unlink_anon_vmas(vma); 549 unlink_file_vma(vma); 550 551 if (is_vm_hugetlb_page(vma)) { 552 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 553 floor, next? next->vm_start: ceiling); 554 } else { 555 /* 556 * Optimization: gather nearby vmas into one call down 557 */ 558 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 559 && !is_vm_hugetlb_page(next)) { 560 vma = next; 561 next = vma->vm_next; 562 unlink_anon_vmas(vma); 563 unlink_file_vma(vma); 564 } 565 free_pgd_range(tlb, addr, vma->vm_end, 566 floor, next? next->vm_start: ceiling); 567 } 568 vma = next; 569 } 570 } 571 572 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, 573 pmd_t *pmd, unsigned long address) 574 { 575 pgtable_t new = pte_alloc_one(mm, address); 576 int wait_split_huge_page; 577 if (!new) 578 return -ENOMEM; 579 580 /* 581 * Ensure all pte setup (eg. pte page lock and page clearing) are 582 * visible before the pte is made visible to other CPUs by being 583 * put into page tables. 584 * 585 * The other side of the story is the pointer chasing in the page 586 * table walking code (when walking the page table without locking; 587 * ie. most of the time). Fortunately, these data accesses consist 588 * of a chain of data-dependent loads, meaning most CPUs (alpha 589 * being the notable exception) will already guarantee loads are 590 * seen in-order. See the alpha page table accessors for the 591 * smp_read_barrier_depends() barriers in page table walking code. 592 */ 593 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 594 595 spin_lock(&mm->page_table_lock); 596 wait_split_huge_page = 0; 597 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 598 mm->nr_ptes++; 599 pmd_populate(mm, pmd, new); 600 new = NULL; 601 } else if (unlikely(pmd_trans_splitting(*pmd))) 602 wait_split_huge_page = 1; 603 spin_unlock(&mm->page_table_lock); 604 if (new) 605 pte_free(mm, new); 606 if (wait_split_huge_page) 607 wait_split_huge_page(vma->anon_vma, pmd); 608 return 0; 609 } 610 611 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 612 { 613 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 614 if (!new) 615 return -ENOMEM; 616 617 smp_wmb(); /* See comment in __pte_alloc */ 618 619 spin_lock(&init_mm.page_table_lock); 620 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 621 pmd_populate_kernel(&init_mm, pmd, new); 622 new = NULL; 623 } else 624 VM_BUG_ON(pmd_trans_splitting(*pmd)); 625 spin_unlock(&init_mm.page_table_lock); 626 if (new) 627 pte_free_kernel(&init_mm, new); 628 return 0; 629 } 630 631 static inline void init_rss_vec(int *rss) 632 { 633 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 634 } 635 636 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 637 { 638 int i; 639 640 if (current->mm == mm) 641 sync_mm_rss(mm); 642 for (i = 0; i < NR_MM_COUNTERS; i++) 643 if (rss[i]) 644 add_mm_counter(mm, i, rss[i]); 645 } 646 647 /* 648 * This function is called to print an error when a bad pte 649 * is found. For example, we might have a PFN-mapped pte in 650 * a region that doesn't allow it. 651 * 652 * The calling function must still handle the error. 653 */ 654 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 655 pte_t pte, struct page *page) 656 { 657 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 658 pud_t *pud = pud_offset(pgd, addr); 659 pmd_t *pmd = pmd_offset(pud, addr); 660 struct address_space *mapping; 661 pgoff_t index; 662 static unsigned long resume; 663 static unsigned long nr_shown; 664 static unsigned long nr_unshown; 665 666 /* 667 * Allow a burst of 60 reports, then keep quiet for that minute; 668 * or allow a steady drip of one report per second. 669 */ 670 if (nr_shown == 60) { 671 if (time_before(jiffies, resume)) { 672 nr_unshown++; 673 return; 674 } 675 if (nr_unshown) { 676 printk(KERN_ALERT 677 "BUG: Bad page map: %lu messages suppressed\n", 678 nr_unshown); 679 nr_unshown = 0; 680 } 681 nr_shown = 0; 682 } 683 if (nr_shown++ == 0) 684 resume = jiffies + 60 * HZ; 685 686 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 687 index = linear_page_index(vma, addr); 688 689 printk(KERN_ALERT 690 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 691 current->comm, 692 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 693 if (page) 694 dump_page(page); 695 printk(KERN_ALERT 696 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 697 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 698 /* 699 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 700 */ 701 if (vma->vm_ops) 702 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n", 703 (unsigned long)vma->vm_ops->fault); 704 if (vma->vm_file && vma->vm_file->f_op) 705 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n", 706 (unsigned long)vma->vm_file->f_op->mmap); 707 dump_stack(); 708 add_taint(TAINT_BAD_PAGE); 709 } 710 711 static inline int is_cow_mapping(vm_flags_t flags) 712 { 713 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 714 } 715 716 #ifndef is_zero_pfn 717 static inline int is_zero_pfn(unsigned long pfn) 718 { 719 return pfn == zero_pfn; 720 } 721 #endif 722 723 #ifndef my_zero_pfn 724 static inline unsigned long my_zero_pfn(unsigned long addr) 725 { 726 return zero_pfn; 727 } 728 #endif 729 730 /* 731 * vm_normal_page -- This function gets the "struct page" associated with a pte. 732 * 733 * "Special" mappings do not wish to be associated with a "struct page" (either 734 * it doesn't exist, or it exists but they don't want to touch it). In this 735 * case, NULL is returned here. "Normal" mappings do have a struct page. 736 * 737 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 738 * pte bit, in which case this function is trivial. Secondly, an architecture 739 * may not have a spare pte bit, which requires a more complicated scheme, 740 * described below. 741 * 742 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 743 * special mapping (even if there are underlying and valid "struct pages"). 744 * COWed pages of a VM_PFNMAP are always normal. 745 * 746 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 747 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 748 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 749 * mapping will always honor the rule 750 * 751 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 752 * 753 * And for normal mappings this is false. 754 * 755 * This restricts such mappings to be a linear translation from virtual address 756 * to pfn. To get around this restriction, we allow arbitrary mappings so long 757 * as the vma is not a COW mapping; in that case, we know that all ptes are 758 * special (because none can have been COWed). 759 * 760 * 761 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 762 * 763 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 764 * page" backing, however the difference is that _all_ pages with a struct 765 * page (that is, those where pfn_valid is true) are refcounted and considered 766 * normal pages by the VM. The disadvantage is that pages are refcounted 767 * (which can be slower and simply not an option for some PFNMAP users). The 768 * advantage is that we don't have to follow the strict linearity rule of 769 * PFNMAP mappings in order to support COWable mappings. 770 * 771 */ 772 #ifdef __HAVE_ARCH_PTE_SPECIAL 773 # define HAVE_PTE_SPECIAL 1 774 #else 775 # define HAVE_PTE_SPECIAL 0 776 #endif 777 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 778 pte_t pte) 779 { 780 unsigned long pfn = pte_pfn(pte); 781 782 if (HAVE_PTE_SPECIAL) { 783 if (likely(!pte_special(pte))) 784 goto check_pfn; 785 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 786 return NULL; 787 if (!is_zero_pfn(pfn)) 788 print_bad_pte(vma, addr, pte, NULL); 789 return NULL; 790 } 791 792 /* !HAVE_PTE_SPECIAL case follows: */ 793 794 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 795 if (vma->vm_flags & VM_MIXEDMAP) { 796 if (!pfn_valid(pfn)) 797 return NULL; 798 goto out; 799 } else { 800 unsigned long off; 801 off = (addr - vma->vm_start) >> PAGE_SHIFT; 802 if (pfn == vma->vm_pgoff + off) 803 return NULL; 804 if (!is_cow_mapping(vma->vm_flags)) 805 return NULL; 806 } 807 } 808 809 if (is_zero_pfn(pfn)) 810 return NULL; 811 check_pfn: 812 if (unlikely(pfn > highest_memmap_pfn)) { 813 print_bad_pte(vma, addr, pte, NULL); 814 return NULL; 815 } 816 817 /* 818 * NOTE! We still have PageReserved() pages in the page tables. 819 * eg. VDSO mappings can cause them to exist. 820 */ 821 out: 822 return pfn_to_page(pfn); 823 } 824 825 /* 826 * copy one vm_area from one task to the other. Assumes the page tables 827 * already present in the new task to be cleared in the whole range 828 * covered by this vma. 829 */ 830 831 static inline unsigned long 832 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 833 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 834 unsigned long addr, int *rss) 835 { 836 unsigned long vm_flags = vma->vm_flags; 837 pte_t pte = *src_pte; 838 struct page *page; 839 840 /* pte contains position in swap or file, so copy. */ 841 if (unlikely(!pte_present(pte))) { 842 if (!pte_file(pte)) { 843 swp_entry_t entry = pte_to_swp_entry(pte); 844 845 if (swap_duplicate(entry) < 0) 846 return entry.val; 847 848 /* make sure dst_mm is on swapoff's mmlist. */ 849 if (unlikely(list_empty(&dst_mm->mmlist))) { 850 spin_lock(&mmlist_lock); 851 if (list_empty(&dst_mm->mmlist)) 852 list_add(&dst_mm->mmlist, 853 &src_mm->mmlist); 854 spin_unlock(&mmlist_lock); 855 } 856 if (likely(!non_swap_entry(entry))) 857 rss[MM_SWAPENTS]++; 858 else if (is_migration_entry(entry)) { 859 page = migration_entry_to_page(entry); 860 861 if (PageAnon(page)) 862 rss[MM_ANONPAGES]++; 863 else 864 rss[MM_FILEPAGES]++; 865 866 if (is_write_migration_entry(entry) && 867 is_cow_mapping(vm_flags)) { 868 /* 869 * COW mappings require pages in both 870 * parent and child to be set to read. 871 */ 872 make_migration_entry_read(&entry); 873 pte = swp_entry_to_pte(entry); 874 set_pte_at(src_mm, addr, src_pte, pte); 875 } 876 } 877 } 878 goto out_set_pte; 879 } 880 881 /* 882 * If it's a COW mapping, write protect it both 883 * in the parent and the child 884 */ 885 if (is_cow_mapping(vm_flags)) { 886 ptep_set_wrprotect(src_mm, addr, src_pte); 887 pte = pte_wrprotect(pte); 888 } 889 890 /* 891 * If it's a shared mapping, mark it clean in 892 * the child 893 */ 894 if (vm_flags & VM_SHARED) 895 pte = pte_mkclean(pte); 896 pte = pte_mkold(pte); 897 898 page = vm_normal_page(vma, addr, pte); 899 if (page) { 900 get_page(page); 901 page_dup_rmap(page); 902 if (PageAnon(page)) 903 rss[MM_ANONPAGES]++; 904 else 905 rss[MM_FILEPAGES]++; 906 } 907 908 out_set_pte: 909 set_pte_at(dst_mm, addr, dst_pte, pte); 910 return 0; 911 } 912 913 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 914 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 915 unsigned long addr, unsigned long end) 916 { 917 pte_t *orig_src_pte, *orig_dst_pte; 918 pte_t *src_pte, *dst_pte; 919 spinlock_t *src_ptl, *dst_ptl; 920 int progress = 0; 921 int rss[NR_MM_COUNTERS]; 922 swp_entry_t entry = (swp_entry_t){0}; 923 924 again: 925 init_rss_vec(rss); 926 927 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 928 if (!dst_pte) 929 return -ENOMEM; 930 src_pte = pte_offset_map(src_pmd, addr); 931 src_ptl = pte_lockptr(src_mm, src_pmd); 932 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 933 orig_src_pte = src_pte; 934 orig_dst_pte = dst_pte; 935 arch_enter_lazy_mmu_mode(); 936 937 do { 938 /* 939 * We are holding two locks at this point - either of them 940 * could generate latencies in another task on another CPU. 941 */ 942 if (progress >= 32) { 943 progress = 0; 944 if (need_resched() || 945 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 946 break; 947 } 948 if (pte_none(*src_pte)) { 949 progress++; 950 continue; 951 } 952 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 953 vma, addr, rss); 954 if (entry.val) 955 break; 956 progress += 8; 957 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 958 959 arch_leave_lazy_mmu_mode(); 960 spin_unlock(src_ptl); 961 pte_unmap(orig_src_pte); 962 add_mm_rss_vec(dst_mm, rss); 963 pte_unmap_unlock(orig_dst_pte, dst_ptl); 964 cond_resched(); 965 966 if (entry.val) { 967 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 968 return -ENOMEM; 969 progress = 0; 970 } 971 if (addr != end) 972 goto again; 973 return 0; 974 } 975 976 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 977 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 978 unsigned long addr, unsigned long end) 979 { 980 pmd_t *src_pmd, *dst_pmd; 981 unsigned long next; 982 983 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 984 if (!dst_pmd) 985 return -ENOMEM; 986 src_pmd = pmd_offset(src_pud, addr); 987 do { 988 next = pmd_addr_end(addr, end); 989 if (pmd_trans_huge(*src_pmd)) { 990 int err; 991 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); 992 err = copy_huge_pmd(dst_mm, src_mm, 993 dst_pmd, src_pmd, addr, vma); 994 if (err == -ENOMEM) 995 return -ENOMEM; 996 if (!err) 997 continue; 998 /* fall through */ 999 } 1000 if (pmd_none_or_clear_bad(src_pmd)) 1001 continue; 1002 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 1003 vma, addr, next)) 1004 return -ENOMEM; 1005 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 1006 return 0; 1007 } 1008 1009 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1010 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 1011 unsigned long addr, unsigned long end) 1012 { 1013 pud_t *src_pud, *dst_pud; 1014 unsigned long next; 1015 1016 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 1017 if (!dst_pud) 1018 return -ENOMEM; 1019 src_pud = pud_offset(src_pgd, addr); 1020 do { 1021 next = pud_addr_end(addr, end); 1022 if (pud_none_or_clear_bad(src_pud)) 1023 continue; 1024 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 1025 vma, addr, next)) 1026 return -ENOMEM; 1027 } while (dst_pud++, src_pud++, addr = next, addr != end); 1028 return 0; 1029 } 1030 1031 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1032 struct vm_area_struct *vma) 1033 { 1034 pgd_t *src_pgd, *dst_pgd; 1035 unsigned long next; 1036 unsigned long addr = vma->vm_start; 1037 unsigned long end = vma->vm_end; 1038 int ret; 1039 1040 /* 1041 * Don't copy ptes where a page fault will fill them correctly. 1042 * Fork becomes much lighter when there are big shared or private 1043 * readonly mappings. The tradeoff is that copy_page_range is more 1044 * efficient than faulting. 1045 */ 1046 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 1047 if (!vma->anon_vma) 1048 return 0; 1049 } 1050 1051 if (is_vm_hugetlb_page(vma)) 1052 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 1053 1054 if (unlikely(is_pfn_mapping(vma))) { 1055 /* 1056 * We do not free on error cases below as remove_vma 1057 * gets called on error from higher level routine 1058 */ 1059 ret = track_pfn_vma_copy(vma); 1060 if (ret) 1061 return ret; 1062 } 1063 1064 /* 1065 * We need to invalidate the secondary MMU mappings only when 1066 * there could be a permission downgrade on the ptes of the 1067 * parent mm. And a permission downgrade will only happen if 1068 * is_cow_mapping() returns true. 1069 */ 1070 if (is_cow_mapping(vma->vm_flags)) 1071 mmu_notifier_invalidate_range_start(src_mm, addr, end); 1072 1073 ret = 0; 1074 dst_pgd = pgd_offset(dst_mm, addr); 1075 src_pgd = pgd_offset(src_mm, addr); 1076 do { 1077 next = pgd_addr_end(addr, end); 1078 if (pgd_none_or_clear_bad(src_pgd)) 1079 continue; 1080 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 1081 vma, addr, next))) { 1082 ret = -ENOMEM; 1083 break; 1084 } 1085 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1086 1087 if (is_cow_mapping(vma->vm_flags)) 1088 mmu_notifier_invalidate_range_end(src_mm, 1089 vma->vm_start, end); 1090 return ret; 1091 } 1092 1093 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1094 struct vm_area_struct *vma, pmd_t *pmd, 1095 unsigned long addr, unsigned long end, 1096 struct zap_details *details) 1097 { 1098 struct mm_struct *mm = tlb->mm; 1099 int force_flush = 0; 1100 int rss[NR_MM_COUNTERS]; 1101 spinlock_t *ptl; 1102 pte_t *start_pte; 1103 pte_t *pte; 1104 1105 again: 1106 init_rss_vec(rss); 1107 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1108 pte = start_pte; 1109 arch_enter_lazy_mmu_mode(); 1110 do { 1111 pte_t ptent = *pte; 1112 if (pte_none(ptent)) { 1113 continue; 1114 } 1115 1116 if (pte_present(ptent)) { 1117 struct page *page; 1118 1119 page = vm_normal_page(vma, addr, ptent); 1120 if (unlikely(details) && page) { 1121 /* 1122 * unmap_shared_mapping_pages() wants to 1123 * invalidate cache without truncating: 1124 * unmap shared but keep private pages. 1125 */ 1126 if (details->check_mapping && 1127 details->check_mapping != page->mapping) 1128 continue; 1129 /* 1130 * Each page->index must be checked when 1131 * invalidating or truncating nonlinear. 1132 */ 1133 if (details->nonlinear_vma && 1134 (page->index < details->first_index || 1135 page->index > details->last_index)) 1136 continue; 1137 } 1138 ptent = ptep_get_and_clear_full(mm, addr, pte, 1139 tlb->fullmm); 1140 tlb_remove_tlb_entry(tlb, pte, addr); 1141 if (unlikely(!page)) 1142 continue; 1143 if (unlikely(details) && details->nonlinear_vma 1144 && linear_page_index(details->nonlinear_vma, 1145 addr) != page->index) 1146 set_pte_at(mm, addr, pte, 1147 pgoff_to_pte(page->index)); 1148 if (PageAnon(page)) 1149 rss[MM_ANONPAGES]--; 1150 else { 1151 if (pte_dirty(ptent)) 1152 set_page_dirty(page); 1153 if (pte_young(ptent) && 1154 likely(!VM_SequentialReadHint(vma))) 1155 mark_page_accessed(page); 1156 rss[MM_FILEPAGES]--; 1157 } 1158 page_remove_rmap(page); 1159 if (unlikely(page_mapcount(page) < 0)) 1160 print_bad_pte(vma, addr, ptent, page); 1161 force_flush = !__tlb_remove_page(tlb, page); 1162 if (force_flush) 1163 break; 1164 continue; 1165 } 1166 /* 1167 * If details->check_mapping, we leave swap entries; 1168 * if details->nonlinear_vma, we leave file entries. 1169 */ 1170 if (unlikely(details)) 1171 continue; 1172 if (pte_file(ptent)) { 1173 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 1174 print_bad_pte(vma, addr, ptent, NULL); 1175 } else { 1176 swp_entry_t entry = pte_to_swp_entry(ptent); 1177 1178 if (!non_swap_entry(entry)) 1179 rss[MM_SWAPENTS]--; 1180 else if (is_migration_entry(entry)) { 1181 struct page *page; 1182 1183 page = migration_entry_to_page(entry); 1184 1185 if (PageAnon(page)) 1186 rss[MM_ANONPAGES]--; 1187 else 1188 rss[MM_FILEPAGES]--; 1189 } 1190 if (unlikely(!free_swap_and_cache(entry))) 1191 print_bad_pte(vma, addr, ptent, NULL); 1192 } 1193 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1194 } while (pte++, addr += PAGE_SIZE, addr != end); 1195 1196 add_mm_rss_vec(mm, rss); 1197 arch_leave_lazy_mmu_mode(); 1198 pte_unmap_unlock(start_pte, ptl); 1199 1200 /* 1201 * mmu_gather ran out of room to batch pages, we break out of 1202 * the PTE lock to avoid doing the potential expensive TLB invalidate 1203 * and page-free while holding it. 1204 */ 1205 if (force_flush) { 1206 force_flush = 0; 1207 tlb_flush_mmu(tlb); 1208 if (addr != end) 1209 goto again; 1210 } 1211 1212 return addr; 1213 } 1214 1215 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1216 struct vm_area_struct *vma, pud_t *pud, 1217 unsigned long addr, unsigned long end, 1218 struct zap_details *details) 1219 { 1220 pmd_t *pmd; 1221 unsigned long next; 1222 1223 pmd = pmd_offset(pud, addr); 1224 do { 1225 next = pmd_addr_end(addr, end); 1226 if (pmd_trans_huge(*pmd)) { 1227 if (next - addr != HPAGE_PMD_SIZE) { 1228 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem)); 1229 split_huge_page_pmd(vma->vm_mm, pmd); 1230 } else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1231 goto next; 1232 /* fall through */ 1233 } 1234 /* 1235 * Here there can be other concurrent MADV_DONTNEED or 1236 * trans huge page faults running, and if the pmd is 1237 * none or trans huge it can change under us. This is 1238 * because MADV_DONTNEED holds the mmap_sem in read 1239 * mode. 1240 */ 1241 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1242 goto next; 1243 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1244 next: 1245 cond_resched(); 1246 } while (pmd++, addr = next, addr != end); 1247 1248 return addr; 1249 } 1250 1251 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1252 struct vm_area_struct *vma, pgd_t *pgd, 1253 unsigned long addr, unsigned long end, 1254 struct zap_details *details) 1255 { 1256 pud_t *pud; 1257 unsigned long next; 1258 1259 pud = pud_offset(pgd, addr); 1260 do { 1261 next = pud_addr_end(addr, end); 1262 if (pud_none_or_clear_bad(pud)) 1263 continue; 1264 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1265 } while (pud++, addr = next, addr != end); 1266 1267 return addr; 1268 } 1269 1270 static void unmap_page_range(struct mmu_gather *tlb, 1271 struct vm_area_struct *vma, 1272 unsigned long addr, unsigned long end, 1273 struct zap_details *details) 1274 { 1275 pgd_t *pgd; 1276 unsigned long next; 1277 1278 if (details && !details->check_mapping && !details->nonlinear_vma) 1279 details = NULL; 1280 1281 BUG_ON(addr >= end); 1282 mem_cgroup_uncharge_start(); 1283 tlb_start_vma(tlb, vma); 1284 pgd = pgd_offset(vma->vm_mm, addr); 1285 do { 1286 next = pgd_addr_end(addr, end); 1287 if (pgd_none_or_clear_bad(pgd)) 1288 continue; 1289 next = zap_pud_range(tlb, vma, pgd, addr, next, details); 1290 } while (pgd++, addr = next, addr != end); 1291 tlb_end_vma(tlb, vma); 1292 mem_cgroup_uncharge_end(); 1293 } 1294 1295 1296 static void unmap_single_vma(struct mmu_gather *tlb, 1297 struct vm_area_struct *vma, unsigned long start_addr, 1298 unsigned long end_addr, unsigned long *nr_accounted, 1299 struct zap_details *details) 1300 { 1301 unsigned long start = max(vma->vm_start, start_addr); 1302 unsigned long end; 1303 1304 if (start >= vma->vm_end) 1305 return; 1306 end = min(vma->vm_end, end_addr); 1307 if (end <= vma->vm_start) 1308 return; 1309 1310 if (vma->vm_flags & VM_ACCOUNT) 1311 *nr_accounted += (end - start) >> PAGE_SHIFT; 1312 1313 if (unlikely(is_pfn_mapping(vma))) 1314 untrack_pfn_vma(vma, 0, 0); 1315 1316 if (start != end) { 1317 if (unlikely(is_vm_hugetlb_page(vma))) { 1318 /* 1319 * It is undesirable to test vma->vm_file as it 1320 * should be non-null for valid hugetlb area. 1321 * However, vm_file will be NULL in the error 1322 * cleanup path of do_mmap_pgoff. When 1323 * hugetlbfs ->mmap method fails, 1324 * do_mmap_pgoff() nullifies vma->vm_file 1325 * before calling this function to clean up. 1326 * Since no pte has actually been setup, it is 1327 * safe to do nothing in this case. 1328 */ 1329 if (vma->vm_file) 1330 unmap_hugepage_range(vma, start, end, NULL); 1331 } else 1332 unmap_page_range(tlb, vma, start, end, details); 1333 } 1334 } 1335 1336 /** 1337 * unmap_vmas - unmap a range of memory covered by a list of vma's 1338 * @tlb: address of the caller's struct mmu_gather 1339 * @vma: the starting vma 1340 * @start_addr: virtual address at which to start unmapping 1341 * @end_addr: virtual address at which to end unmapping 1342 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 1343 * @details: details of nonlinear truncation or shared cache invalidation 1344 * 1345 * Unmap all pages in the vma list. 1346 * 1347 * Only addresses between `start' and `end' will be unmapped. 1348 * 1349 * The VMA list must be sorted in ascending virtual address order. 1350 * 1351 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1352 * range after unmap_vmas() returns. So the only responsibility here is to 1353 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1354 * drops the lock and schedules. 1355 */ 1356 void unmap_vmas(struct mmu_gather *tlb, 1357 struct vm_area_struct *vma, unsigned long start_addr, 1358 unsigned long end_addr, unsigned long *nr_accounted, 1359 struct zap_details *details) 1360 { 1361 struct mm_struct *mm = vma->vm_mm; 1362 1363 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1364 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1365 unmap_single_vma(tlb, vma, start_addr, end_addr, nr_accounted, 1366 details); 1367 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1368 } 1369 1370 /** 1371 * zap_page_range - remove user pages in a given range 1372 * @vma: vm_area_struct holding the applicable pages 1373 * @address: starting address of pages to zap 1374 * @size: number of bytes to zap 1375 * @details: details of nonlinear truncation or shared cache invalidation 1376 * 1377 * Caller must protect the VMA list 1378 */ 1379 void zap_page_range(struct vm_area_struct *vma, unsigned long address, 1380 unsigned long size, struct zap_details *details) 1381 { 1382 struct mm_struct *mm = vma->vm_mm; 1383 struct mmu_gather tlb; 1384 unsigned long end = address + size; 1385 unsigned long nr_accounted = 0; 1386 1387 lru_add_drain(); 1388 tlb_gather_mmu(&tlb, mm, 0); 1389 update_hiwater_rss(mm); 1390 unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 1391 tlb_finish_mmu(&tlb, address, end); 1392 } 1393 1394 /** 1395 * zap_page_range_single - remove user pages in a given range 1396 * @vma: vm_area_struct holding the applicable pages 1397 * @address: starting address of pages to zap 1398 * @size: number of bytes to zap 1399 * @details: details of nonlinear truncation or shared cache invalidation 1400 * 1401 * The range must fit into one VMA. 1402 */ 1403 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1404 unsigned long size, struct zap_details *details) 1405 { 1406 struct mm_struct *mm = vma->vm_mm; 1407 struct mmu_gather tlb; 1408 unsigned long end = address + size; 1409 unsigned long nr_accounted = 0; 1410 1411 lru_add_drain(); 1412 tlb_gather_mmu(&tlb, mm, 0); 1413 update_hiwater_rss(mm); 1414 mmu_notifier_invalidate_range_start(mm, address, end); 1415 unmap_single_vma(&tlb, vma, address, end, &nr_accounted, details); 1416 mmu_notifier_invalidate_range_end(mm, address, end); 1417 tlb_finish_mmu(&tlb, address, end); 1418 } 1419 1420 /** 1421 * zap_vma_ptes - remove ptes mapping the vma 1422 * @vma: vm_area_struct holding ptes to be zapped 1423 * @address: starting address of pages to zap 1424 * @size: number of bytes to zap 1425 * 1426 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1427 * 1428 * The entire address range must be fully contained within the vma. 1429 * 1430 * Returns 0 if successful. 1431 */ 1432 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1433 unsigned long size) 1434 { 1435 if (address < vma->vm_start || address + size > vma->vm_end || 1436 !(vma->vm_flags & VM_PFNMAP)) 1437 return -1; 1438 zap_page_range_single(vma, address, size, NULL); 1439 return 0; 1440 } 1441 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1442 1443 /** 1444 * follow_page - look up a page descriptor from a user-virtual address 1445 * @vma: vm_area_struct mapping @address 1446 * @address: virtual address to look up 1447 * @flags: flags modifying lookup behaviour 1448 * 1449 * @flags can have FOLL_ flags set, defined in <linux/mm.h> 1450 * 1451 * Returns the mapped (struct page *), %NULL if no mapping exists, or 1452 * an error pointer if there is a mapping to something not represented 1453 * by a page descriptor (see also vm_normal_page()). 1454 */ 1455 struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1456 unsigned int flags) 1457 { 1458 pgd_t *pgd; 1459 pud_t *pud; 1460 pmd_t *pmd; 1461 pte_t *ptep, pte; 1462 spinlock_t *ptl; 1463 struct page *page; 1464 struct mm_struct *mm = vma->vm_mm; 1465 1466 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 1467 if (!IS_ERR(page)) { 1468 BUG_ON(flags & FOLL_GET); 1469 goto out; 1470 } 1471 1472 page = NULL; 1473 pgd = pgd_offset(mm, address); 1474 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 1475 goto no_page_table; 1476 1477 pud = pud_offset(pgd, address); 1478 if (pud_none(*pud)) 1479 goto no_page_table; 1480 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { 1481 BUG_ON(flags & FOLL_GET); 1482 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); 1483 goto out; 1484 } 1485 if (unlikely(pud_bad(*pud))) 1486 goto no_page_table; 1487 1488 pmd = pmd_offset(pud, address); 1489 if (pmd_none(*pmd)) 1490 goto no_page_table; 1491 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) { 1492 BUG_ON(flags & FOLL_GET); 1493 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 1494 goto out; 1495 } 1496 if (pmd_trans_huge(*pmd)) { 1497 if (flags & FOLL_SPLIT) { 1498 split_huge_page_pmd(mm, pmd); 1499 goto split_fallthrough; 1500 } 1501 spin_lock(&mm->page_table_lock); 1502 if (likely(pmd_trans_huge(*pmd))) { 1503 if (unlikely(pmd_trans_splitting(*pmd))) { 1504 spin_unlock(&mm->page_table_lock); 1505 wait_split_huge_page(vma->anon_vma, pmd); 1506 } else { 1507 page = follow_trans_huge_pmd(mm, address, 1508 pmd, flags); 1509 spin_unlock(&mm->page_table_lock); 1510 goto out; 1511 } 1512 } else 1513 spin_unlock(&mm->page_table_lock); 1514 /* fall through */ 1515 } 1516 split_fallthrough: 1517 if (unlikely(pmd_bad(*pmd))) 1518 goto no_page_table; 1519 1520 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 1521 1522 pte = *ptep; 1523 if (!pte_present(pte)) 1524 goto no_page; 1525 if ((flags & FOLL_WRITE) && !pte_write(pte)) 1526 goto unlock; 1527 1528 page = vm_normal_page(vma, address, pte); 1529 if (unlikely(!page)) { 1530 if ((flags & FOLL_DUMP) || 1531 !is_zero_pfn(pte_pfn(pte))) 1532 goto bad_page; 1533 page = pte_page(pte); 1534 } 1535 1536 if (flags & FOLL_GET) 1537 get_page_foll(page); 1538 if (flags & FOLL_TOUCH) { 1539 if ((flags & FOLL_WRITE) && 1540 !pte_dirty(pte) && !PageDirty(page)) 1541 set_page_dirty(page); 1542 /* 1543 * pte_mkyoung() would be more correct here, but atomic care 1544 * is needed to avoid losing the dirty bit: it is easier to use 1545 * mark_page_accessed(). 1546 */ 1547 mark_page_accessed(page); 1548 } 1549 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1550 /* 1551 * The preliminary mapping check is mainly to avoid the 1552 * pointless overhead of lock_page on the ZERO_PAGE 1553 * which might bounce very badly if there is contention. 1554 * 1555 * If the page is already locked, we don't need to 1556 * handle it now - vmscan will handle it later if and 1557 * when it attempts to reclaim the page. 1558 */ 1559 if (page->mapping && trylock_page(page)) { 1560 lru_add_drain(); /* push cached pages to LRU */ 1561 /* 1562 * Because we lock page here and migration is 1563 * blocked by the pte's page reference, we need 1564 * only check for file-cache page truncation. 1565 */ 1566 if (page->mapping) 1567 mlock_vma_page(page); 1568 unlock_page(page); 1569 } 1570 } 1571 unlock: 1572 pte_unmap_unlock(ptep, ptl); 1573 out: 1574 return page; 1575 1576 bad_page: 1577 pte_unmap_unlock(ptep, ptl); 1578 return ERR_PTR(-EFAULT); 1579 1580 no_page: 1581 pte_unmap_unlock(ptep, ptl); 1582 if (!pte_none(pte)) 1583 return page; 1584 1585 no_page_table: 1586 /* 1587 * When core dumping an enormous anonymous area that nobody 1588 * has touched so far, we don't want to allocate unnecessary pages or 1589 * page tables. Return error instead of NULL to skip handle_mm_fault, 1590 * then get_dump_page() will return NULL to leave a hole in the dump. 1591 * But we can only make this optimization where a hole would surely 1592 * be zero-filled if handle_mm_fault() actually did handle it. 1593 */ 1594 if ((flags & FOLL_DUMP) && 1595 (!vma->vm_ops || !vma->vm_ops->fault)) 1596 return ERR_PTR(-EFAULT); 1597 return page; 1598 } 1599 1600 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) 1601 { 1602 return stack_guard_page_start(vma, addr) || 1603 stack_guard_page_end(vma, addr+PAGE_SIZE); 1604 } 1605 1606 /** 1607 * __get_user_pages() - pin user pages in memory 1608 * @tsk: task_struct of target task 1609 * @mm: mm_struct of target mm 1610 * @start: starting user address 1611 * @nr_pages: number of pages from start to pin 1612 * @gup_flags: flags modifying pin behaviour 1613 * @pages: array that receives pointers to the pages pinned. 1614 * Should be at least nr_pages long. Or NULL, if caller 1615 * only intends to ensure the pages are faulted in. 1616 * @vmas: array of pointers to vmas corresponding to each page. 1617 * Or NULL if the caller does not require them. 1618 * @nonblocking: whether waiting for disk IO or mmap_sem contention 1619 * 1620 * Returns number of pages pinned. This may be fewer than the number 1621 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1622 * were pinned, returns -errno. Each page returned must be released 1623 * with a put_page() call when it is finished with. vmas will only 1624 * remain valid while mmap_sem is held. 1625 * 1626 * Must be called with mmap_sem held for read or write. 1627 * 1628 * __get_user_pages walks a process's page tables and takes a reference to 1629 * each struct page that each user address corresponds to at a given 1630 * instant. That is, it takes the page that would be accessed if a user 1631 * thread accesses the given user virtual address at that instant. 1632 * 1633 * This does not guarantee that the page exists in the user mappings when 1634 * __get_user_pages returns, and there may even be a completely different 1635 * page there in some cases (eg. if mmapped pagecache has been invalidated 1636 * and subsequently re faulted). However it does guarantee that the page 1637 * won't be freed completely. And mostly callers simply care that the page 1638 * contains data that was valid *at some point in time*. Typically, an IO 1639 * or similar operation cannot guarantee anything stronger anyway because 1640 * locks can't be held over the syscall boundary. 1641 * 1642 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If 1643 * the page is written to, set_page_dirty (or set_page_dirty_lock, as 1644 * appropriate) must be called after the page is finished with, and 1645 * before put_page is called. 1646 * 1647 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO 1648 * or mmap_sem contention, and if waiting is needed to pin all pages, 1649 * *@nonblocking will be set to 0. 1650 * 1651 * In most cases, get_user_pages or get_user_pages_fast should be used 1652 * instead of __get_user_pages. __get_user_pages should be used only if 1653 * you need some special @gup_flags. 1654 */ 1655 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1656 unsigned long start, int nr_pages, unsigned int gup_flags, 1657 struct page **pages, struct vm_area_struct **vmas, 1658 int *nonblocking) 1659 { 1660 int i; 1661 unsigned long vm_flags; 1662 1663 if (nr_pages <= 0) 1664 return 0; 1665 1666 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); 1667 1668 /* 1669 * Require read or write permissions. 1670 * If FOLL_FORCE is set, we only require the "MAY" flags. 1671 */ 1672 vm_flags = (gup_flags & FOLL_WRITE) ? 1673 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 1674 vm_flags &= (gup_flags & FOLL_FORCE) ? 1675 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 1676 i = 0; 1677 1678 do { 1679 struct vm_area_struct *vma; 1680 1681 vma = find_extend_vma(mm, start); 1682 if (!vma && in_gate_area(mm, start)) { 1683 unsigned long pg = start & PAGE_MASK; 1684 pgd_t *pgd; 1685 pud_t *pud; 1686 pmd_t *pmd; 1687 pte_t *pte; 1688 1689 /* user gate pages are read-only */ 1690 if (gup_flags & FOLL_WRITE) 1691 return i ? : -EFAULT; 1692 if (pg > TASK_SIZE) 1693 pgd = pgd_offset_k(pg); 1694 else 1695 pgd = pgd_offset_gate(mm, pg); 1696 BUG_ON(pgd_none(*pgd)); 1697 pud = pud_offset(pgd, pg); 1698 BUG_ON(pud_none(*pud)); 1699 pmd = pmd_offset(pud, pg); 1700 if (pmd_none(*pmd)) 1701 return i ? : -EFAULT; 1702 VM_BUG_ON(pmd_trans_huge(*pmd)); 1703 pte = pte_offset_map(pmd, pg); 1704 if (pte_none(*pte)) { 1705 pte_unmap(pte); 1706 return i ? : -EFAULT; 1707 } 1708 vma = get_gate_vma(mm); 1709 if (pages) { 1710 struct page *page; 1711 1712 page = vm_normal_page(vma, start, *pte); 1713 if (!page) { 1714 if (!(gup_flags & FOLL_DUMP) && 1715 is_zero_pfn(pte_pfn(*pte))) 1716 page = pte_page(*pte); 1717 else { 1718 pte_unmap(pte); 1719 return i ? : -EFAULT; 1720 } 1721 } 1722 pages[i] = page; 1723 get_page(page); 1724 } 1725 pte_unmap(pte); 1726 goto next_page; 1727 } 1728 1729 if (!vma || 1730 (vma->vm_flags & (VM_IO | VM_PFNMAP)) || 1731 !(vm_flags & vma->vm_flags)) 1732 return i ? : -EFAULT; 1733 1734 if (is_vm_hugetlb_page(vma)) { 1735 i = follow_hugetlb_page(mm, vma, pages, vmas, 1736 &start, &nr_pages, i, gup_flags); 1737 continue; 1738 } 1739 1740 do { 1741 struct page *page; 1742 unsigned int foll_flags = gup_flags; 1743 1744 /* 1745 * If we have a pending SIGKILL, don't keep faulting 1746 * pages and potentially allocating memory. 1747 */ 1748 if (unlikely(fatal_signal_pending(current))) 1749 return i ? i : -ERESTARTSYS; 1750 1751 cond_resched(); 1752 while (!(page = follow_page(vma, start, foll_flags))) { 1753 int ret; 1754 unsigned int fault_flags = 0; 1755 1756 /* For mlock, just skip the stack guard page. */ 1757 if (foll_flags & FOLL_MLOCK) { 1758 if (stack_guard_page(vma, start)) 1759 goto next_page; 1760 } 1761 if (foll_flags & FOLL_WRITE) 1762 fault_flags |= FAULT_FLAG_WRITE; 1763 if (nonblocking) 1764 fault_flags |= FAULT_FLAG_ALLOW_RETRY; 1765 if (foll_flags & FOLL_NOWAIT) 1766 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT); 1767 1768 ret = handle_mm_fault(mm, vma, start, 1769 fault_flags); 1770 1771 if (ret & VM_FAULT_ERROR) { 1772 if (ret & VM_FAULT_OOM) 1773 return i ? i : -ENOMEM; 1774 if (ret & (VM_FAULT_HWPOISON | 1775 VM_FAULT_HWPOISON_LARGE)) { 1776 if (i) 1777 return i; 1778 else if (gup_flags & FOLL_HWPOISON) 1779 return -EHWPOISON; 1780 else 1781 return -EFAULT; 1782 } 1783 if (ret & VM_FAULT_SIGBUS) 1784 return i ? i : -EFAULT; 1785 BUG(); 1786 } 1787 1788 if (tsk) { 1789 if (ret & VM_FAULT_MAJOR) 1790 tsk->maj_flt++; 1791 else 1792 tsk->min_flt++; 1793 } 1794 1795 if (ret & VM_FAULT_RETRY) { 1796 if (nonblocking) 1797 *nonblocking = 0; 1798 return i; 1799 } 1800 1801 /* 1802 * The VM_FAULT_WRITE bit tells us that 1803 * do_wp_page has broken COW when necessary, 1804 * even if maybe_mkwrite decided not to set 1805 * pte_write. We can thus safely do subsequent 1806 * page lookups as if they were reads. But only 1807 * do so when looping for pte_write is futile: 1808 * in some cases userspace may also be wanting 1809 * to write to the gotten user page, which a 1810 * read fault here might prevent (a readonly 1811 * page might get reCOWed by userspace write). 1812 */ 1813 if ((ret & VM_FAULT_WRITE) && 1814 !(vma->vm_flags & VM_WRITE)) 1815 foll_flags &= ~FOLL_WRITE; 1816 1817 cond_resched(); 1818 } 1819 if (IS_ERR(page)) 1820 return i ? i : PTR_ERR(page); 1821 if (pages) { 1822 pages[i] = page; 1823 1824 flush_anon_page(vma, page, start); 1825 flush_dcache_page(page); 1826 } 1827 next_page: 1828 if (vmas) 1829 vmas[i] = vma; 1830 i++; 1831 start += PAGE_SIZE; 1832 nr_pages--; 1833 } while (nr_pages && start < vma->vm_end); 1834 } while (nr_pages); 1835 return i; 1836 } 1837 EXPORT_SYMBOL(__get_user_pages); 1838 1839 /* 1840 * fixup_user_fault() - manually resolve a user page fault 1841 * @tsk: the task_struct to use for page fault accounting, or 1842 * NULL if faults are not to be recorded. 1843 * @mm: mm_struct of target mm 1844 * @address: user address 1845 * @fault_flags:flags to pass down to handle_mm_fault() 1846 * 1847 * This is meant to be called in the specific scenario where for locking reasons 1848 * we try to access user memory in atomic context (within a pagefault_disable() 1849 * section), this returns -EFAULT, and we want to resolve the user fault before 1850 * trying again. 1851 * 1852 * Typically this is meant to be used by the futex code. 1853 * 1854 * The main difference with get_user_pages() is that this function will 1855 * unconditionally call handle_mm_fault() which will in turn perform all the 1856 * necessary SW fixup of the dirty and young bits in the PTE, while 1857 * handle_mm_fault() only guarantees to update these in the struct page. 1858 * 1859 * This is important for some architectures where those bits also gate the 1860 * access permission to the page because they are maintained in software. On 1861 * such architectures, gup() will not be enough to make a subsequent access 1862 * succeed. 1863 * 1864 * This should be called with the mm_sem held for read. 1865 */ 1866 int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, 1867 unsigned long address, unsigned int fault_flags) 1868 { 1869 struct vm_area_struct *vma; 1870 int ret; 1871 1872 vma = find_extend_vma(mm, address); 1873 if (!vma || address < vma->vm_start) 1874 return -EFAULT; 1875 1876 ret = handle_mm_fault(mm, vma, address, fault_flags); 1877 if (ret & VM_FAULT_ERROR) { 1878 if (ret & VM_FAULT_OOM) 1879 return -ENOMEM; 1880 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) 1881 return -EHWPOISON; 1882 if (ret & VM_FAULT_SIGBUS) 1883 return -EFAULT; 1884 BUG(); 1885 } 1886 if (tsk) { 1887 if (ret & VM_FAULT_MAJOR) 1888 tsk->maj_flt++; 1889 else 1890 tsk->min_flt++; 1891 } 1892 return 0; 1893 } 1894 1895 /* 1896 * get_user_pages() - pin user pages in memory 1897 * @tsk: the task_struct to use for page fault accounting, or 1898 * NULL if faults are not to be recorded. 1899 * @mm: mm_struct of target mm 1900 * @start: starting user address 1901 * @nr_pages: number of pages from start to pin 1902 * @write: whether pages will be written to by the caller 1903 * @force: whether to force write access even if user mapping is 1904 * readonly. This will result in the page being COWed even 1905 * in MAP_SHARED mappings. You do not want this. 1906 * @pages: array that receives pointers to the pages pinned. 1907 * Should be at least nr_pages long. Or NULL, if caller 1908 * only intends to ensure the pages are faulted in. 1909 * @vmas: array of pointers to vmas corresponding to each page. 1910 * Or NULL if the caller does not require them. 1911 * 1912 * Returns number of pages pinned. This may be fewer than the number 1913 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1914 * were pinned, returns -errno. Each page returned must be released 1915 * with a put_page() call when it is finished with. vmas will only 1916 * remain valid while mmap_sem is held. 1917 * 1918 * Must be called with mmap_sem held for read or write. 1919 * 1920 * get_user_pages walks a process's page tables and takes a reference to 1921 * each struct page that each user address corresponds to at a given 1922 * instant. That is, it takes the page that would be accessed if a user 1923 * thread accesses the given user virtual address at that instant. 1924 * 1925 * This does not guarantee that the page exists in the user mappings when 1926 * get_user_pages returns, and there may even be a completely different 1927 * page there in some cases (eg. if mmapped pagecache has been invalidated 1928 * and subsequently re faulted). However it does guarantee that the page 1929 * won't be freed completely. And mostly callers simply care that the page 1930 * contains data that was valid *at some point in time*. Typically, an IO 1931 * or similar operation cannot guarantee anything stronger anyway because 1932 * locks can't be held over the syscall boundary. 1933 * 1934 * If write=0, the page must not be written to. If the page is written to, 1935 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called 1936 * after the page is finished with, and before put_page is called. 1937 * 1938 * get_user_pages is typically used for fewer-copy IO operations, to get a 1939 * handle on the memory by some means other than accesses via the user virtual 1940 * addresses. The pages may be submitted for DMA to devices or accessed via 1941 * their kernel linear mapping (via the kmap APIs). Care should be taken to 1942 * use the correct cache flushing APIs. 1943 * 1944 * See also get_user_pages_fast, for performance critical applications. 1945 */ 1946 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1947 unsigned long start, int nr_pages, int write, int force, 1948 struct page **pages, struct vm_area_struct **vmas) 1949 { 1950 int flags = FOLL_TOUCH; 1951 1952 if (pages) 1953 flags |= FOLL_GET; 1954 if (write) 1955 flags |= FOLL_WRITE; 1956 if (force) 1957 flags |= FOLL_FORCE; 1958 1959 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 1960 NULL); 1961 } 1962 EXPORT_SYMBOL(get_user_pages); 1963 1964 /** 1965 * get_dump_page() - pin user page in memory while writing it to core dump 1966 * @addr: user address 1967 * 1968 * Returns struct page pointer of user page pinned for dump, 1969 * to be freed afterwards by page_cache_release() or put_page(). 1970 * 1971 * Returns NULL on any kind of failure - a hole must then be inserted into 1972 * the corefile, to preserve alignment with its headers; and also returns 1973 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - 1974 * allowing a hole to be left in the corefile to save diskspace. 1975 * 1976 * Called without mmap_sem, but after all other threads have been killed. 1977 */ 1978 #ifdef CONFIG_ELF_CORE 1979 struct page *get_dump_page(unsigned long addr) 1980 { 1981 struct vm_area_struct *vma; 1982 struct page *page; 1983 1984 if (__get_user_pages(current, current->mm, addr, 1, 1985 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma, 1986 NULL) < 1) 1987 return NULL; 1988 flush_cache_page(vma, addr, page_to_pfn(page)); 1989 return page; 1990 } 1991 #endif /* CONFIG_ELF_CORE */ 1992 1993 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 1994 spinlock_t **ptl) 1995 { 1996 pgd_t * pgd = pgd_offset(mm, addr); 1997 pud_t * pud = pud_alloc(mm, pgd, addr); 1998 if (pud) { 1999 pmd_t * pmd = pmd_alloc(mm, pud, addr); 2000 if (pmd) { 2001 VM_BUG_ON(pmd_trans_huge(*pmd)); 2002 return pte_alloc_map_lock(mm, pmd, addr, ptl); 2003 } 2004 } 2005 return NULL; 2006 } 2007 2008 /* 2009 * This is the old fallback for page remapping. 2010 * 2011 * For historical reasons, it only allows reserved pages. Only 2012 * old drivers should use this, and they needed to mark their 2013 * pages reserved for the old functions anyway. 2014 */ 2015 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 2016 struct page *page, pgprot_t prot) 2017 { 2018 struct mm_struct *mm = vma->vm_mm; 2019 int retval; 2020 pte_t *pte; 2021 spinlock_t *ptl; 2022 2023 retval = -EINVAL; 2024 if (PageAnon(page)) 2025 goto out; 2026 retval = -ENOMEM; 2027 flush_dcache_page(page); 2028 pte = get_locked_pte(mm, addr, &ptl); 2029 if (!pte) 2030 goto out; 2031 retval = -EBUSY; 2032 if (!pte_none(*pte)) 2033 goto out_unlock; 2034 2035 /* Ok, finally just insert the thing.. */ 2036 get_page(page); 2037 inc_mm_counter_fast(mm, MM_FILEPAGES); 2038 page_add_file_rmap(page); 2039 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 2040 2041 retval = 0; 2042 pte_unmap_unlock(pte, ptl); 2043 return retval; 2044 out_unlock: 2045 pte_unmap_unlock(pte, ptl); 2046 out: 2047 return retval; 2048 } 2049 2050 /** 2051 * vm_insert_page - insert single page into user vma 2052 * @vma: user vma to map to 2053 * @addr: target user address of this page 2054 * @page: source kernel page 2055 * 2056 * This allows drivers to insert individual pages they've allocated 2057 * into a user vma. 2058 * 2059 * The page has to be a nice clean _individual_ kernel allocation. 2060 * If you allocate a compound page, you need to have marked it as 2061 * such (__GFP_COMP), or manually just split the page up yourself 2062 * (see split_page()). 2063 * 2064 * NOTE! Traditionally this was done with "remap_pfn_range()" which 2065 * took an arbitrary page protection parameter. This doesn't allow 2066 * that. Your vma protection will have to be set up correctly, which 2067 * means that if you want a shared writable mapping, you'd better 2068 * ask for a shared writable mapping! 2069 * 2070 * The page does not need to be reserved. 2071 */ 2072 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 2073 struct page *page) 2074 { 2075 if (addr < vma->vm_start || addr >= vma->vm_end) 2076 return -EFAULT; 2077 if (!page_count(page)) 2078 return -EINVAL; 2079 vma->vm_flags |= VM_INSERTPAGE; 2080 return insert_page(vma, addr, page, vma->vm_page_prot); 2081 } 2082 EXPORT_SYMBOL(vm_insert_page); 2083 2084 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2085 unsigned long pfn, pgprot_t prot) 2086 { 2087 struct mm_struct *mm = vma->vm_mm; 2088 int retval; 2089 pte_t *pte, entry; 2090 spinlock_t *ptl; 2091 2092 retval = -ENOMEM; 2093 pte = get_locked_pte(mm, addr, &ptl); 2094 if (!pte) 2095 goto out; 2096 retval = -EBUSY; 2097 if (!pte_none(*pte)) 2098 goto out_unlock; 2099 2100 /* Ok, finally just insert the thing.. */ 2101 entry = pte_mkspecial(pfn_pte(pfn, prot)); 2102 set_pte_at(mm, addr, pte, entry); 2103 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 2104 2105 retval = 0; 2106 out_unlock: 2107 pte_unmap_unlock(pte, ptl); 2108 out: 2109 return retval; 2110 } 2111 2112 /** 2113 * vm_insert_pfn - insert single pfn into user vma 2114 * @vma: user vma to map to 2115 * @addr: target user address of this page 2116 * @pfn: source kernel pfn 2117 * 2118 * Similar to vm_inert_page, this allows drivers to insert individual pages 2119 * they've allocated into a user vma. Same comments apply. 2120 * 2121 * This function should only be called from a vm_ops->fault handler, and 2122 * in that case the handler should return NULL. 2123 * 2124 * vma cannot be a COW mapping. 2125 * 2126 * As this is called only for pages that do not currently exist, we 2127 * do not need to flush old virtual caches or the TLB. 2128 */ 2129 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2130 unsigned long pfn) 2131 { 2132 int ret; 2133 pgprot_t pgprot = vma->vm_page_prot; 2134 /* 2135 * Technically, architectures with pte_special can avoid all these 2136 * restrictions (same for remap_pfn_range). However we would like 2137 * consistency in testing and feature parity among all, so we should 2138 * try to keep these invariants in place for everybody. 2139 */ 2140 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 2141 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 2142 (VM_PFNMAP|VM_MIXEDMAP)); 2143 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 2144 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 2145 2146 if (addr < vma->vm_start || addr >= vma->vm_end) 2147 return -EFAULT; 2148 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE)) 2149 return -EINVAL; 2150 2151 ret = insert_pfn(vma, addr, pfn, pgprot); 2152 2153 if (ret) 2154 untrack_pfn_vma(vma, pfn, PAGE_SIZE); 2155 2156 return ret; 2157 } 2158 EXPORT_SYMBOL(vm_insert_pfn); 2159 2160 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 2161 unsigned long pfn) 2162 { 2163 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 2164 2165 if (addr < vma->vm_start || addr >= vma->vm_end) 2166 return -EFAULT; 2167 2168 /* 2169 * If we don't have pte special, then we have to use the pfn_valid() 2170 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 2171 * refcount the page if pfn_valid is true (hence insert_page rather 2172 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 2173 * without pte special, it would there be refcounted as a normal page. 2174 */ 2175 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 2176 struct page *page; 2177 2178 page = pfn_to_page(pfn); 2179 return insert_page(vma, addr, page, vma->vm_page_prot); 2180 } 2181 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 2182 } 2183 EXPORT_SYMBOL(vm_insert_mixed); 2184 2185 /* 2186 * maps a range of physical memory into the requested pages. the old 2187 * mappings are removed. any references to nonexistent pages results 2188 * in null mappings (currently treated as "copy-on-access") 2189 */ 2190 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 2191 unsigned long addr, unsigned long end, 2192 unsigned long pfn, pgprot_t prot) 2193 { 2194 pte_t *pte; 2195 spinlock_t *ptl; 2196 2197 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 2198 if (!pte) 2199 return -ENOMEM; 2200 arch_enter_lazy_mmu_mode(); 2201 do { 2202 BUG_ON(!pte_none(*pte)); 2203 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 2204 pfn++; 2205 } while (pte++, addr += PAGE_SIZE, addr != end); 2206 arch_leave_lazy_mmu_mode(); 2207 pte_unmap_unlock(pte - 1, ptl); 2208 return 0; 2209 } 2210 2211 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 2212 unsigned long addr, unsigned long end, 2213 unsigned long pfn, pgprot_t prot) 2214 { 2215 pmd_t *pmd; 2216 unsigned long next; 2217 2218 pfn -= addr >> PAGE_SHIFT; 2219 pmd = pmd_alloc(mm, pud, addr); 2220 if (!pmd) 2221 return -ENOMEM; 2222 VM_BUG_ON(pmd_trans_huge(*pmd)); 2223 do { 2224 next = pmd_addr_end(addr, end); 2225 if (remap_pte_range(mm, pmd, addr, next, 2226 pfn + (addr >> PAGE_SHIFT), prot)) 2227 return -ENOMEM; 2228 } while (pmd++, addr = next, addr != end); 2229 return 0; 2230 } 2231 2232 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 2233 unsigned long addr, unsigned long end, 2234 unsigned long pfn, pgprot_t prot) 2235 { 2236 pud_t *pud; 2237 unsigned long next; 2238 2239 pfn -= addr >> PAGE_SHIFT; 2240 pud = pud_alloc(mm, pgd, addr); 2241 if (!pud) 2242 return -ENOMEM; 2243 do { 2244 next = pud_addr_end(addr, end); 2245 if (remap_pmd_range(mm, pud, addr, next, 2246 pfn + (addr >> PAGE_SHIFT), prot)) 2247 return -ENOMEM; 2248 } while (pud++, addr = next, addr != end); 2249 return 0; 2250 } 2251 2252 /** 2253 * remap_pfn_range - remap kernel memory to userspace 2254 * @vma: user vma to map to 2255 * @addr: target user address to start at 2256 * @pfn: physical address of kernel memory 2257 * @size: size of map area 2258 * @prot: page protection flags for this mapping 2259 * 2260 * Note: this is only safe if the mm semaphore is held when called. 2261 */ 2262 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 2263 unsigned long pfn, unsigned long size, pgprot_t prot) 2264 { 2265 pgd_t *pgd; 2266 unsigned long next; 2267 unsigned long end = addr + PAGE_ALIGN(size); 2268 struct mm_struct *mm = vma->vm_mm; 2269 int err; 2270 2271 /* 2272 * Physically remapped pages are special. Tell the 2273 * rest of the world about it: 2274 * VM_IO tells people not to look at these pages 2275 * (accesses can have side effects). 2276 * VM_RESERVED is specified all over the place, because 2277 * in 2.4 it kept swapout's vma scan off this vma; but 2278 * in 2.6 the LRU scan won't even find its pages, so this 2279 * flag means no more than count its pages in reserved_vm, 2280 * and omit it from core dump, even when VM_IO turned off. 2281 * VM_PFNMAP tells the core MM that the base pages are just 2282 * raw PFN mappings, and do not have a "struct page" associated 2283 * with them. 2284 * 2285 * There's a horrible special case to handle copy-on-write 2286 * behaviour that some programs depend on. We mark the "original" 2287 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 2288 */ 2289 if (addr == vma->vm_start && end == vma->vm_end) { 2290 vma->vm_pgoff = pfn; 2291 vma->vm_flags |= VM_PFN_AT_MMAP; 2292 } else if (is_cow_mapping(vma->vm_flags)) 2293 return -EINVAL; 2294 2295 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 2296 2297 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size)); 2298 if (err) { 2299 /* 2300 * To indicate that track_pfn related cleanup is not 2301 * needed from higher level routine calling unmap_vmas 2302 */ 2303 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP); 2304 vma->vm_flags &= ~VM_PFN_AT_MMAP; 2305 return -EINVAL; 2306 } 2307 2308 BUG_ON(addr >= end); 2309 pfn -= addr >> PAGE_SHIFT; 2310 pgd = pgd_offset(mm, addr); 2311 flush_cache_range(vma, addr, end); 2312 do { 2313 next = pgd_addr_end(addr, end); 2314 err = remap_pud_range(mm, pgd, addr, next, 2315 pfn + (addr >> PAGE_SHIFT), prot); 2316 if (err) 2317 break; 2318 } while (pgd++, addr = next, addr != end); 2319 2320 if (err) 2321 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size)); 2322 2323 return err; 2324 } 2325 EXPORT_SYMBOL(remap_pfn_range); 2326 2327 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 2328 unsigned long addr, unsigned long end, 2329 pte_fn_t fn, void *data) 2330 { 2331 pte_t *pte; 2332 int err; 2333 pgtable_t token; 2334 spinlock_t *uninitialized_var(ptl); 2335 2336 pte = (mm == &init_mm) ? 2337 pte_alloc_kernel(pmd, addr) : 2338 pte_alloc_map_lock(mm, pmd, addr, &ptl); 2339 if (!pte) 2340 return -ENOMEM; 2341 2342 BUG_ON(pmd_huge(*pmd)); 2343 2344 arch_enter_lazy_mmu_mode(); 2345 2346 token = pmd_pgtable(*pmd); 2347 2348 do { 2349 err = fn(pte++, token, addr, data); 2350 if (err) 2351 break; 2352 } while (addr += PAGE_SIZE, addr != end); 2353 2354 arch_leave_lazy_mmu_mode(); 2355 2356 if (mm != &init_mm) 2357 pte_unmap_unlock(pte-1, ptl); 2358 return err; 2359 } 2360 2361 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 2362 unsigned long addr, unsigned long end, 2363 pte_fn_t fn, void *data) 2364 { 2365 pmd_t *pmd; 2366 unsigned long next; 2367 int err; 2368 2369 BUG_ON(pud_huge(*pud)); 2370 2371 pmd = pmd_alloc(mm, pud, addr); 2372 if (!pmd) 2373 return -ENOMEM; 2374 do { 2375 next = pmd_addr_end(addr, end); 2376 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 2377 if (err) 2378 break; 2379 } while (pmd++, addr = next, addr != end); 2380 return err; 2381 } 2382 2383 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 2384 unsigned long addr, unsigned long end, 2385 pte_fn_t fn, void *data) 2386 { 2387 pud_t *pud; 2388 unsigned long next; 2389 int err; 2390 2391 pud = pud_alloc(mm, pgd, addr); 2392 if (!pud) 2393 return -ENOMEM; 2394 do { 2395 next = pud_addr_end(addr, end); 2396 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 2397 if (err) 2398 break; 2399 } while (pud++, addr = next, addr != end); 2400 return err; 2401 } 2402 2403 /* 2404 * Scan a region of virtual memory, filling in page tables as necessary 2405 * and calling a provided function on each leaf page table. 2406 */ 2407 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2408 unsigned long size, pte_fn_t fn, void *data) 2409 { 2410 pgd_t *pgd; 2411 unsigned long next; 2412 unsigned long end = addr + size; 2413 int err; 2414 2415 BUG_ON(addr >= end); 2416 pgd = pgd_offset(mm, addr); 2417 do { 2418 next = pgd_addr_end(addr, end); 2419 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 2420 if (err) 2421 break; 2422 } while (pgd++, addr = next, addr != end); 2423 2424 return err; 2425 } 2426 EXPORT_SYMBOL_GPL(apply_to_page_range); 2427 2428 /* 2429 * handle_pte_fault chooses page fault handler according to an entry 2430 * which was read non-atomically. Before making any commitment, on 2431 * those architectures or configurations (e.g. i386 with PAE) which 2432 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault 2433 * must check under lock before unmapping the pte and proceeding 2434 * (but do_wp_page is only called after already making such a check; 2435 * and do_anonymous_page can safely check later on). 2436 */ 2437 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 2438 pte_t *page_table, pte_t orig_pte) 2439 { 2440 int same = 1; 2441 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 2442 if (sizeof(pte_t) > sizeof(unsigned long)) { 2443 spinlock_t *ptl = pte_lockptr(mm, pmd); 2444 spin_lock(ptl); 2445 same = pte_same(*page_table, orig_pte); 2446 spin_unlock(ptl); 2447 } 2448 #endif 2449 pte_unmap(page_table); 2450 return same; 2451 } 2452 2453 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 2454 { 2455 /* 2456 * If the source page was a PFN mapping, we don't have 2457 * a "struct page" for it. We do a best-effort copy by 2458 * just copying from the original user address. If that 2459 * fails, we just zero-fill it. Live with it. 2460 */ 2461 if (unlikely(!src)) { 2462 void *kaddr = kmap_atomic(dst); 2463 void __user *uaddr = (void __user *)(va & PAGE_MASK); 2464 2465 /* 2466 * This really shouldn't fail, because the page is there 2467 * in the page tables. But it might just be unreadable, 2468 * in which case we just give up and fill the result with 2469 * zeroes. 2470 */ 2471 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 2472 clear_page(kaddr); 2473 kunmap_atomic(kaddr); 2474 flush_dcache_page(dst); 2475 } else 2476 copy_user_highpage(dst, src, va, vma); 2477 } 2478 2479 /* 2480 * This routine handles present pages, when users try to write 2481 * to a shared page. It is done by copying the page to a new address 2482 * and decrementing the shared-page counter for the old page. 2483 * 2484 * Note that this routine assumes that the protection checks have been 2485 * done by the caller (the low-level page fault routine in most cases). 2486 * Thus we can safely just mark it writable once we've done any necessary 2487 * COW. 2488 * 2489 * We also mark the page dirty at this point even though the page will 2490 * change only once the write actually happens. This avoids a few races, 2491 * and potentially makes it more efficient. 2492 * 2493 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2494 * but allow concurrent faults), with pte both mapped and locked. 2495 * We return with mmap_sem still held, but pte unmapped and unlocked. 2496 */ 2497 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 2498 unsigned long address, pte_t *page_table, pmd_t *pmd, 2499 spinlock_t *ptl, pte_t orig_pte) 2500 __releases(ptl) 2501 { 2502 struct page *old_page, *new_page; 2503 pte_t entry; 2504 int ret = 0; 2505 int page_mkwrite = 0; 2506 struct page *dirty_page = NULL; 2507 2508 old_page = vm_normal_page(vma, address, orig_pte); 2509 if (!old_page) { 2510 /* 2511 * VM_MIXEDMAP !pfn_valid() case 2512 * 2513 * We should not cow pages in a shared writeable mapping. 2514 * Just mark the pages writable as we can't do any dirty 2515 * accounting on raw pfn maps. 2516 */ 2517 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2518 (VM_WRITE|VM_SHARED)) 2519 goto reuse; 2520 goto gotten; 2521 } 2522 2523 /* 2524 * Take out anonymous pages first, anonymous shared vmas are 2525 * not dirty accountable. 2526 */ 2527 if (PageAnon(old_page) && !PageKsm(old_page)) { 2528 if (!trylock_page(old_page)) { 2529 page_cache_get(old_page); 2530 pte_unmap_unlock(page_table, ptl); 2531 lock_page(old_page); 2532 page_table = pte_offset_map_lock(mm, pmd, address, 2533 &ptl); 2534 if (!pte_same(*page_table, orig_pte)) { 2535 unlock_page(old_page); 2536 goto unlock; 2537 } 2538 page_cache_release(old_page); 2539 } 2540 if (reuse_swap_page(old_page)) { 2541 /* 2542 * The page is all ours. Move it to our anon_vma so 2543 * the rmap code will not search our parent or siblings. 2544 * Protected against the rmap code by the page lock. 2545 */ 2546 page_move_anon_rmap(old_page, vma, address); 2547 unlock_page(old_page); 2548 goto reuse; 2549 } 2550 unlock_page(old_page); 2551 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2552 (VM_WRITE|VM_SHARED))) { 2553 /* 2554 * Only catch write-faults on shared writable pages, 2555 * read-only shared pages can get COWed by 2556 * get_user_pages(.write=1, .force=1). 2557 */ 2558 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2559 struct vm_fault vmf; 2560 int tmp; 2561 2562 vmf.virtual_address = (void __user *)(address & 2563 PAGE_MASK); 2564 vmf.pgoff = old_page->index; 2565 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2566 vmf.page = old_page; 2567 2568 /* 2569 * Notify the address space that the page is about to 2570 * become writable so that it can prohibit this or wait 2571 * for the page to get into an appropriate state. 2572 * 2573 * We do this without the lock held, so that it can 2574 * sleep if it needs to. 2575 */ 2576 page_cache_get(old_page); 2577 pte_unmap_unlock(page_table, ptl); 2578 2579 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 2580 if (unlikely(tmp & 2581 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2582 ret = tmp; 2583 goto unwritable_page; 2584 } 2585 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 2586 lock_page(old_page); 2587 if (!old_page->mapping) { 2588 ret = 0; /* retry the fault */ 2589 unlock_page(old_page); 2590 goto unwritable_page; 2591 } 2592 } else 2593 VM_BUG_ON(!PageLocked(old_page)); 2594 2595 /* 2596 * Since we dropped the lock we need to revalidate 2597 * the PTE as someone else may have changed it. If 2598 * they did, we just return, as we can count on the 2599 * MMU to tell us if they didn't also make it writable. 2600 */ 2601 page_table = pte_offset_map_lock(mm, pmd, address, 2602 &ptl); 2603 if (!pte_same(*page_table, orig_pte)) { 2604 unlock_page(old_page); 2605 goto unlock; 2606 } 2607 2608 page_mkwrite = 1; 2609 } 2610 dirty_page = old_page; 2611 get_page(dirty_page); 2612 2613 reuse: 2614 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2615 entry = pte_mkyoung(orig_pte); 2616 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2617 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2618 update_mmu_cache(vma, address, page_table); 2619 pte_unmap_unlock(page_table, ptl); 2620 ret |= VM_FAULT_WRITE; 2621 2622 if (!dirty_page) 2623 return ret; 2624 2625 /* 2626 * Yes, Virginia, this is actually required to prevent a race 2627 * with clear_page_dirty_for_io() from clearing the page dirty 2628 * bit after it clear all dirty ptes, but before a racing 2629 * do_wp_page installs a dirty pte. 2630 * 2631 * __do_fault is protected similarly. 2632 */ 2633 if (!page_mkwrite) { 2634 wait_on_page_locked(dirty_page); 2635 set_page_dirty_balance(dirty_page, page_mkwrite); 2636 } 2637 put_page(dirty_page); 2638 if (page_mkwrite) { 2639 struct address_space *mapping = dirty_page->mapping; 2640 2641 set_page_dirty(dirty_page); 2642 unlock_page(dirty_page); 2643 page_cache_release(dirty_page); 2644 if (mapping) { 2645 /* 2646 * Some device drivers do not set page.mapping 2647 * but still dirty their pages 2648 */ 2649 balance_dirty_pages_ratelimited(mapping); 2650 } 2651 } 2652 2653 /* file_update_time outside page_lock */ 2654 if (vma->vm_file) 2655 file_update_time(vma->vm_file); 2656 2657 return ret; 2658 } 2659 2660 /* 2661 * Ok, we need to copy. Oh, well.. 2662 */ 2663 page_cache_get(old_page); 2664 gotten: 2665 pte_unmap_unlock(page_table, ptl); 2666 2667 if (unlikely(anon_vma_prepare(vma))) 2668 goto oom; 2669 2670 if (is_zero_pfn(pte_pfn(orig_pte))) { 2671 new_page = alloc_zeroed_user_highpage_movable(vma, address); 2672 if (!new_page) 2673 goto oom; 2674 } else { 2675 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2676 if (!new_page) 2677 goto oom; 2678 cow_user_page(new_page, old_page, address, vma); 2679 } 2680 __SetPageUptodate(new_page); 2681 2682 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) 2683 goto oom_free_new; 2684 2685 /* 2686 * Re-check the pte - we dropped the lock 2687 */ 2688 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2689 if (likely(pte_same(*page_table, orig_pte))) { 2690 if (old_page) { 2691 if (!PageAnon(old_page)) { 2692 dec_mm_counter_fast(mm, MM_FILEPAGES); 2693 inc_mm_counter_fast(mm, MM_ANONPAGES); 2694 } 2695 } else 2696 inc_mm_counter_fast(mm, MM_ANONPAGES); 2697 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2698 entry = mk_pte(new_page, vma->vm_page_prot); 2699 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2700 /* 2701 * Clear the pte entry and flush it first, before updating the 2702 * pte with the new entry. This will avoid a race condition 2703 * seen in the presence of one thread doing SMC and another 2704 * thread doing COW. 2705 */ 2706 ptep_clear_flush(vma, address, page_table); 2707 page_add_new_anon_rmap(new_page, vma, address); 2708 /* 2709 * We call the notify macro here because, when using secondary 2710 * mmu page tables (such as kvm shadow page tables), we want the 2711 * new page to be mapped directly into the secondary page table. 2712 */ 2713 set_pte_at_notify(mm, address, page_table, entry); 2714 update_mmu_cache(vma, address, page_table); 2715 if (old_page) { 2716 /* 2717 * Only after switching the pte to the new page may 2718 * we remove the mapcount here. Otherwise another 2719 * process may come and find the rmap count decremented 2720 * before the pte is switched to the new page, and 2721 * "reuse" the old page writing into it while our pte 2722 * here still points into it and can be read by other 2723 * threads. 2724 * 2725 * The critical issue is to order this 2726 * page_remove_rmap with the ptp_clear_flush above. 2727 * Those stores are ordered by (if nothing else,) 2728 * the barrier present in the atomic_add_negative 2729 * in page_remove_rmap. 2730 * 2731 * Then the TLB flush in ptep_clear_flush ensures that 2732 * no process can access the old page before the 2733 * decremented mapcount is visible. And the old page 2734 * cannot be reused until after the decremented 2735 * mapcount is visible. So transitively, TLBs to 2736 * old page will be flushed before it can be reused. 2737 */ 2738 page_remove_rmap(old_page); 2739 } 2740 2741 /* Free the old page.. */ 2742 new_page = old_page; 2743 ret |= VM_FAULT_WRITE; 2744 } else 2745 mem_cgroup_uncharge_page(new_page); 2746 2747 if (new_page) 2748 page_cache_release(new_page); 2749 unlock: 2750 pte_unmap_unlock(page_table, ptl); 2751 if (old_page) { 2752 /* 2753 * Don't let another task, with possibly unlocked vma, 2754 * keep the mlocked page. 2755 */ 2756 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { 2757 lock_page(old_page); /* LRU manipulation */ 2758 munlock_vma_page(old_page); 2759 unlock_page(old_page); 2760 } 2761 page_cache_release(old_page); 2762 } 2763 return ret; 2764 oom_free_new: 2765 page_cache_release(new_page); 2766 oom: 2767 if (old_page) { 2768 if (page_mkwrite) { 2769 unlock_page(old_page); 2770 page_cache_release(old_page); 2771 } 2772 page_cache_release(old_page); 2773 } 2774 return VM_FAULT_OOM; 2775 2776 unwritable_page: 2777 page_cache_release(old_page); 2778 return ret; 2779 } 2780 2781 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 2782 unsigned long start_addr, unsigned long end_addr, 2783 struct zap_details *details) 2784 { 2785 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 2786 } 2787 2788 static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 2789 struct zap_details *details) 2790 { 2791 struct vm_area_struct *vma; 2792 struct prio_tree_iter iter; 2793 pgoff_t vba, vea, zba, zea; 2794 2795 vma_prio_tree_foreach(vma, &iter, root, 2796 details->first_index, details->last_index) { 2797 2798 vba = vma->vm_pgoff; 2799 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 2800 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2801 zba = details->first_index; 2802 if (zba < vba) 2803 zba = vba; 2804 zea = details->last_index; 2805 if (zea > vea) 2806 zea = vea; 2807 2808 unmap_mapping_range_vma(vma, 2809 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2810 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2811 details); 2812 } 2813 } 2814 2815 static inline void unmap_mapping_range_list(struct list_head *head, 2816 struct zap_details *details) 2817 { 2818 struct vm_area_struct *vma; 2819 2820 /* 2821 * In nonlinear VMAs there is no correspondence between virtual address 2822 * offset and file offset. So we must perform an exhaustive search 2823 * across *all* the pages in each nonlinear VMA, not just the pages 2824 * whose virtual address lies outside the file truncation point. 2825 */ 2826 list_for_each_entry(vma, head, shared.vm_set.list) { 2827 details->nonlinear_vma = vma; 2828 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details); 2829 } 2830 } 2831 2832 /** 2833 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2834 * @mapping: the address space containing mmaps to be unmapped. 2835 * @holebegin: byte in first page to unmap, relative to the start of 2836 * the underlying file. This will be rounded down to a PAGE_SIZE 2837 * boundary. Note that this is different from truncate_pagecache(), which 2838 * must keep the partial page. In contrast, we must get rid of 2839 * partial pages. 2840 * @holelen: size of prospective hole in bytes. This will be rounded 2841 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2842 * end of the file. 2843 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2844 * but 0 when invalidating pagecache, don't throw away private data. 2845 */ 2846 void unmap_mapping_range(struct address_space *mapping, 2847 loff_t const holebegin, loff_t const holelen, int even_cows) 2848 { 2849 struct zap_details details; 2850 pgoff_t hba = holebegin >> PAGE_SHIFT; 2851 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2852 2853 /* Check for overflow. */ 2854 if (sizeof(holelen) > sizeof(hlen)) { 2855 long long holeend = 2856 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2857 if (holeend & ~(long long)ULONG_MAX) 2858 hlen = ULONG_MAX - hba + 1; 2859 } 2860 2861 details.check_mapping = even_cows? NULL: mapping; 2862 details.nonlinear_vma = NULL; 2863 details.first_index = hba; 2864 details.last_index = hba + hlen - 1; 2865 if (details.last_index < details.first_index) 2866 details.last_index = ULONG_MAX; 2867 2868 2869 mutex_lock(&mapping->i_mmap_mutex); 2870 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 2871 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2872 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 2873 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 2874 mutex_unlock(&mapping->i_mmap_mutex); 2875 } 2876 EXPORT_SYMBOL(unmap_mapping_range); 2877 2878 /* 2879 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2880 * but allow concurrent faults), and pte mapped but not yet locked. 2881 * We return with mmap_sem still held, but pte unmapped and unlocked. 2882 */ 2883 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2884 unsigned long address, pte_t *page_table, pmd_t *pmd, 2885 unsigned int flags, pte_t orig_pte) 2886 { 2887 spinlock_t *ptl; 2888 struct page *page, *swapcache = NULL; 2889 swp_entry_t entry; 2890 pte_t pte; 2891 int locked; 2892 struct mem_cgroup *ptr; 2893 int exclusive = 0; 2894 int ret = 0; 2895 2896 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2897 goto out; 2898 2899 entry = pte_to_swp_entry(orig_pte); 2900 if (unlikely(non_swap_entry(entry))) { 2901 if (is_migration_entry(entry)) { 2902 migration_entry_wait(mm, pmd, address); 2903 } else if (is_hwpoison_entry(entry)) { 2904 ret = VM_FAULT_HWPOISON; 2905 } else { 2906 print_bad_pte(vma, address, orig_pte, NULL); 2907 ret = VM_FAULT_SIGBUS; 2908 } 2909 goto out; 2910 } 2911 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2912 page = lookup_swap_cache(entry); 2913 if (!page) { 2914 grab_swap_token(mm); /* Contend for token _before_ read-in */ 2915 page = swapin_readahead(entry, 2916 GFP_HIGHUSER_MOVABLE, vma, address); 2917 if (!page) { 2918 /* 2919 * Back out if somebody else faulted in this pte 2920 * while we released the pte lock. 2921 */ 2922 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2923 if (likely(pte_same(*page_table, orig_pte))) 2924 ret = VM_FAULT_OOM; 2925 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2926 goto unlock; 2927 } 2928 2929 /* Had to read the page from swap area: Major fault */ 2930 ret = VM_FAULT_MAJOR; 2931 count_vm_event(PGMAJFAULT); 2932 mem_cgroup_count_vm_event(mm, PGMAJFAULT); 2933 } else if (PageHWPoison(page)) { 2934 /* 2935 * hwpoisoned dirty swapcache pages are kept for killing 2936 * owner processes (which may be unknown at hwpoison time) 2937 */ 2938 ret = VM_FAULT_HWPOISON; 2939 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2940 goto out_release; 2941 } 2942 2943 locked = lock_page_or_retry(page, mm, flags); 2944 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2945 if (!locked) { 2946 ret |= VM_FAULT_RETRY; 2947 goto out_release; 2948 } 2949 2950 /* 2951 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 2952 * release the swapcache from under us. The page pin, and pte_same 2953 * test below, are not enough to exclude that. Even if it is still 2954 * swapcache, we need to check that the page's swap has not changed. 2955 */ 2956 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) 2957 goto out_page; 2958 2959 if (ksm_might_need_to_copy(page, vma, address)) { 2960 swapcache = page; 2961 page = ksm_does_need_to_copy(page, vma, address); 2962 2963 if (unlikely(!page)) { 2964 ret = VM_FAULT_OOM; 2965 page = swapcache; 2966 swapcache = NULL; 2967 goto out_page; 2968 } 2969 } 2970 2971 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { 2972 ret = VM_FAULT_OOM; 2973 goto out_page; 2974 } 2975 2976 /* 2977 * Back out if somebody else already faulted in this pte. 2978 */ 2979 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2980 if (unlikely(!pte_same(*page_table, orig_pte))) 2981 goto out_nomap; 2982 2983 if (unlikely(!PageUptodate(page))) { 2984 ret = VM_FAULT_SIGBUS; 2985 goto out_nomap; 2986 } 2987 2988 /* 2989 * The page isn't present yet, go ahead with the fault. 2990 * 2991 * Be careful about the sequence of operations here. 2992 * To get its accounting right, reuse_swap_page() must be called 2993 * while the page is counted on swap but not yet in mapcount i.e. 2994 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2995 * must be called after the swap_free(), or it will never succeed. 2996 * Because delete_from_swap_page() may be called by reuse_swap_page(), 2997 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry 2998 * in page->private. In this case, a record in swap_cgroup is silently 2999 * discarded at swap_free(). 3000 */ 3001 3002 inc_mm_counter_fast(mm, MM_ANONPAGES); 3003 dec_mm_counter_fast(mm, MM_SWAPENTS); 3004 pte = mk_pte(page, vma->vm_page_prot); 3005 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 3006 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 3007 flags &= ~FAULT_FLAG_WRITE; 3008 ret |= VM_FAULT_WRITE; 3009 exclusive = 1; 3010 } 3011 flush_icache_page(vma, page); 3012 set_pte_at(mm, address, page_table, pte); 3013 do_page_add_anon_rmap(page, vma, address, exclusive); 3014 /* It's better to call commit-charge after rmap is established */ 3015 mem_cgroup_commit_charge_swapin(page, ptr); 3016 3017 swap_free(entry); 3018 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 3019 try_to_free_swap(page); 3020 unlock_page(page); 3021 if (swapcache) { 3022 /* 3023 * Hold the lock to avoid the swap entry to be reused 3024 * until we take the PT lock for the pte_same() check 3025 * (to avoid false positives from pte_same). For 3026 * further safety release the lock after the swap_free 3027 * so that the swap count won't change under a 3028 * parallel locked swapcache. 3029 */ 3030 unlock_page(swapcache); 3031 page_cache_release(swapcache); 3032 } 3033 3034 if (flags & FAULT_FLAG_WRITE) { 3035 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 3036 if (ret & VM_FAULT_ERROR) 3037 ret &= VM_FAULT_ERROR; 3038 goto out; 3039 } 3040 3041 /* No need to invalidate - it was non-present before */ 3042 update_mmu_cache(vma, address, page_table); 3043 unlock: 3044 pte_unmap_unlock(page_table, ptl); 3045 out: 3046 return ret; 3047 out_nomap: 3048 mem_cgroup_cancel_charge_swapin(ptr); 3049 pte_unmap_unlock(page_table, ptl); 3050 out_page: 3051 unlock_page(page); 3052 out_release: 3053 page_cache_release(page); 3054 if (swapcache) { 3055 unlock_page(swapcache); 3056 page_cache_release(swapcache); 3057 } 3058 return ret; 3059 } 3060 3061 /* 3062 * This is like a special single-page "expand_{down|up}wards()", 3063 * except we must first make sure that 'address{-|+}PAGE_SIZE' 3064 * doesn't hit another vma. 3065 */ 3066 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) 3067 { 3068 address &= PAGE_MASK; 3069 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { 3070 struct vm_area_struct *prev = vma->vm_prev; 3071 3072 /* 3073 * Is there a mapping abutting this one below? 3074 * 3075 * That's only ok if it's the same stack mapping 3076 * that has gotten split.. 3077 */ 3078 if (prev && prev->vm_end == address) 3079 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; 3080 3081 expand_downwards(vma, address - PAGE_SIZE); 3082 } 3083 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { 3084 struct vm_area_struct *next = vma->vm_next; 3085 3086 /* As VM_GROWSDOWN but s/below/above/ */ 3087 if (next && next->vm_start == address + PAGE_SIZE) 3088 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; 3089 3090 expand_upwards(vma, address + PAGE_SIZE); 3091 } 3092 return 0; 3093 } 3094 3095 /* 3096 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3097 * but allow concurrent faults), and pte mapped but not yet locked. 3098 * We return with mmap_sem still held, but pte unmapped and unlocked. 3099 */ 3100 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 3101 unsigned long address, pte_t *page_table, pmd_t *pmd, 3102 unsigned int flags) 3103 { 3104 struct page *page; 3105 spinlock_t *ptl; 3106 pte_t entry; 3107 3108 pte_unmap(page_table); 3109 3110 /* Check if we need to add a guard page to the stack */ 3111 if (check_stack_guard_page(vma, address) < 0) 3112 return VM_FAULT_SIGBUS; 3113 3114 /* Use the zero-page for reads */ 3115 if (!(flags & FAULT_FLAG_WRITE)) { 3116 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), 3117 vma->vm_page_prot)); 3118 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3119 if (!pte_none(*page_table)) 3120 goto unlock; 3121 goto setpte; 3122 } 3123 3124 /* Allocate our own private page. */ 3125 if (unlikely(anon_vma_prepare(vma))) 3126 goto oom; 3127 page = alloc_zeroed_user_highpage_movable(vma, address); 3128 if (!page) 3129 goto oom; 3130 __SetPageUptodate(page); 3131 3132 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) 3133 goto oom_free_page; 3134 3135 entry = mk_pte(page, vma->vm_page_prot); 3136 if (vma->vm_flags & VM_WRITE) 3137 entry = pte_mkwrite(pte_mkdirty(entry)); 3138 3139 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3140 if (!pte_none(*page_table)) 3141 goto release; 3142 3143 inc_mm_counter_fast(mm, MM_ANONPAGES); 3144 page_add_new_anon_rmap(page, vma, address); 3145 setpte: 3146 set_pte_at(mm, address, page_table, entry); 3147 3148 /* No need to invalidate - it was non-present before */ 3149 update_mmu_cache(vma, address, page_table); 3150 unlock: 3151 pte_unmap_unlock(page_table, ptl); 3152 return 0; 3153 release: 3154 mem_cgroup_uncharge_page(page); 3155 page_cache_release(page); 3156 goto unlock; 3157 oom_free_page: 3158 page_cache_release(page); 3159 oom: 3160 return VM_FAULT_OOM; 3161 } 3162 3163 /* 3164 * __do_fault() tries to create a new page mapping. It aggressively 3165 * tries to share with existing pages, but makes a separate copy if 3166 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 3167 * the next page fault. 3168 * 3169 * As this is called only for pages that do not currently exist, we 3170 * do not need to flush old virtual caches or the TLB. 3171 * 3172 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3173 * but allow concurrent faults), and pte neither mapped nor locked. 3174 * We return with mmap_sem still held, but pte unmapped and unlocked. 3175 */ 3176 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3177 unsigned long address, pmd_t *pmd, 3178 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 3179 { 3180 pte_t *page_table; 3181 spinlock_t *ptl; 3182 struct page *page; 3183 struct page *cow_page; 3184 pte_t entry; 3185 int anon = 0; 3186 struct page *dirty_page = NULL; 3187 struct vm_fault vmf; 3188 int ret; 3189 int page_mkwrite = 0; 3190 3191 /* 3192 * If we do COW later, allocate page befor taking lock_page() 3193 * on the file cache page. This will reduce lock holding time. 3194 */ 3195 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { 3196 3197 if (unlikely(anon_vma_prepare(vma))) 3198 return VM_FAULT_OOM; 3199 3200 cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 3201 if (!cow_page) 3202 return VM_FAULT_OOM; 3203 3204 if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) { 3205 page_cache_release(cow_page); 3206 return VM_FAULT_OOM; 3207 } 3208 } else 3209 cow_page = NULL; 3210 3211 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 3212 vmf.pgoff = pgoff; 3213 vmf.flags = flags; 3214 vmf.page = NULL; 3215 3216 ret = vma->vm_ops->fault(vma, &vmf); 3217 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | 3218 VM_FAULT_RETRY))) 3219 goto uncharge_out; 3220 3221 if (unlikely(PageHWPoison(vmf.page))) { 3222 if (ret & VM_FAULT_LOCKED) 3223 unlock_page(vmf.page); 3224 ret = VM_FAULT_HWPOISON; 3225 goto uncharge_out; 3226 } 3227 3228 /* 3229 * For consistency in subsequent calls, make the faulted page always 3230 * locked. 3231 */ 3232 if (unlikely(!(ret & VM_FAULT_LOCKED))) 3233 lock_page(vmf.page); 3234 else 3235 VM_BUG_ON(!PageLocked(vmf.page)); 3236 3237 /* 3238 * Should we do an early C-O-W break? 3239 */ 3240 page = vmf.page; 3241 if (flags & FAULT_FLAG_WRITE) { 3242 if (!(vma->vm_flags & VM_SHARED)) { 3243 page = cow_page; 3244 anon = 1; 3245 copy_user_highpage(page, vmf.page, address, vma); 3246 __SetPageUptodate(page); 3247 } else { 3248 /* 3249 * If the page will be shareable, see if the backing 3250 * address space wants to know that the page is about 3251 * to become writable 3252 */ 3253 if (vma->vm_ops->page_mkwrite) { 3254 int tmp; 3255 3256 unlock_page(page); 3257 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 3258 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 3259 if (unlikely(tmp & 3260 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 3261 ret = tmp; 3262 goto unwritable_page; 3263 } 3264 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 3265 lock_page(page); 3266 if (!page->mapping) { 3267 ret = 0; /* retry the fault */ 3268 unlock_page(page); 3269 goto unwritable_page; 3270 } 3271 } else 3272 VM_BUG_ON(!PageLocked(page)); 3273 page_mkwrite = 1; 3274 } 3275 } 3276 3277 } 3278 3279 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3280 3281 /* 3282 * This silly early PAGE_DIRTY setting removes a race 3283 * due to the bad i386 page protection. But it's valid 3284 * for other architectures too. 3285 * 3286 * Note that if FAULT_FLAG_WRITE is set, we either now have 3287 * an exclusive copy of the page, or this is a shared mapping, 3288 * so we can make it writable and dirty to avoid having to 3289 * handle that later. 3290 */ 3291 /* Only go through if we didn't race with anybody else... */ 3292 if (likely(pte_same(*page_table, orig_pte))) { 3293 flush_icache_page(vma, page); 3294 entry = mk_pte(page, vma->vm_page_prot); 3295 if (flags & FAULT_FLAG_WRITE) 3296 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3297 if (anon) { 3298 inc_mm_counter_fast(mm, MM_ANONPAGES); 3299 page_add_new_anon_rmap(page, vma, address); 3300 } else { 3301 inc_mm_counter_fast(mm, MM_FILEPAGES); 3302 page_add_file_rmap(page); 3303 if (flags & FAULT_FLAG_WRITE) { 3304 dirty_page = page; 3305 get_page(dirty_page); 3306 } 3307 } 3308 set_pte_at(mm, address, page_table, entry); 3309 3310 /* no need to invalidate: a not-present page won't be cached */ 3311 update_mmu_cache(vma, address, page_table); 3312 } else { 3313 if (cow_page) 3314 mem_cgroup_uncharge_page(cow_page); 3315 if (anon) 3316 page_cache_release(page); 3317 else 3318 anon = 1; /* no anon but release faulted_page */ 3319 } 3320 3321 pte_unmap_unlock(page_table, ptl); 3322 3323 if (dirty_page) { 3324 struct address_space *mapping = page->mapping; 3325 3326 if (set_page_dirty(dirty_page)) 3327 page_mkwrite = 1; 3328 unlock_page(dirty_page); 3329 put_page(dirty_page); 3330 if (page_mkwrite && mapping) { 3331 /* 3332 * Some device drivers do not set page.mapping but still 3333 * dirty their pages 3334 */ 3335 balance_dirty_pages_ratelimited(mapping); 3336 } 3337 3338 /* file_update_time outside page_lock */ 3339 if (vma->vm_file) 3340 file_update_time(vma->vm_file); 3341 } else { 3342 unlock_page(vmf.page); 3343 if (anon) 3344 page_cache_release(vmf.page); 3345 } 3346 3347 return ret; 3348 3349 unwritable_page: 3350 page_cache_release(page); 3351 return ret; 3352 uncharge_out: 3353 /* fs's fault handler get error */ 3354 if (cow_page) { 3355 mem_cgroup_uncharge_page(cow_page); 3356 page_cache_release(cow_page); 3357 } 3358 return ret; 3359 } 3360 3361 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3362 unsigned long address, pte_t *page_table, pmd_t *pmd, 3363 unsigned int flags, pte_t orig_pte) 3364 { 3365 pgoff_t pgoff = (((address & PAGE_MASK) 3366 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 3367 3368 pte_unmap(page_table); 3369 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3370 } 3371 3372 /* 3373 * Fault of a previously existing named mapping. Repopulate the pte 3374 * from the encoded file_pte if possible. This enables swappable 3375 * nonlinear vmas. 3376 * 3377 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3378 * but allow concurrent faults), and pte mapped but not yet locked. 3379 * We return with mmap_sem still held, but pte unmapped and unlocked. 3380 */ 3381 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3382 unsigned long address, pte_t *page_table, pmd_t *pmd, 3383 unsigned int flags, pte_t orig_pte) 3384 { 3385 pgoff_t pgoff; 3386 3387 flags |= FAULT_FLAG_NONLINEAR; 3388 3389 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3390 return 0; 3391 3392 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 3393 /* 3394 * Page table corrupted: show pte and kill process. 3395 */ 3396 print_bad_pte(vma, address, orig_pte, NULL); 3397 return VM_FAULT_SIGBUS; 3398 } 3399 3400 pgoff = pte_to_pgoff(orig_pte); 3401 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3402 } 3403 3404 /* 3405 * These routines also need to handle stuff like marking pages dirty 3406 * and/or accessed for architectures that don't do it in hardware (most 3407 * RISC architectures). The early dirtying is also good on the i386. 3408 * 3409 * There is also a hook called "update_mmu_cache()" that architectures 3410 * with external mmu caches can use to update those (ie the Sparc or 3411 * PowerPC hashed page tables that act as extended TLBs). 3412 * 3413 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3414 * but allow concurrent faults), and pte mapped but not yet locked. 3415 * We return with mmap_sem still held, but pte unmapped and unlocked. 3416 */ 3417 int handle_pte_fault(struct mm_struct *mm, 3418 struct vm_area_struct *vma, unsigned long address, 3419 pte_t *pte, pmd_t *pmd, unsigned int flags) 3420 { 3421 pte_t entry; 3422 spinlock_t *ptl; 3423 3424 entry = *pte; 3425 if (!pte_present(entry)) { 3426 if (pte_none(entry)) { 3427 if (vma->vm_ops) { 3428 if (likely(vma->vm_ops->fault)) 3429 return do_linear_fault(mm, vma, address, 3430 pte, pmd, flags, entry); 3431 } 3432 return do_anonymous_page(mm, vma, address, 3433 pte, pmd, flags); 3434 } 3435 if (pte_file(entry)) 3436 return do_nonlinear_fault(mm, vma, address, 3437 pte, pmd, flags, entry); 3438 return do_swap_page(mm, vma, address, 3439 pte, pmd, flags, entry); 3440 } 3441 3442 ptl = pte_lockptr(mm, pmd); 3443 spin_lock(ptl); 3444 if (unlikely(!pte_same(*pte, entry))) 3445 goto unlock; 3446 if (flags & FAULT_FLAG_WRITE) { 3447 if (!pte_write(entry)) 3448 return do_wp_page(mm, vma, address, 3449 pte, pmd, ptl, entry); 3450 entry = pte_mkdirty(entry); 3451 } 3452 entry = pte_mkyoung(entry); 3453 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 3454 update_mmu_cache(vma, address, pte); 3455 } else { 3456 /* 3457 * This is needed only for protection faults but the arch code 3458 * is not yet telling us if this is a protection fault or not. 3459 * This still avoids useless tlb flushes for .text page faults 3460 * with threads. 3461 */ 3462 if (flags & FAULT_FLAG_WRITE) 3463 flush_tlb_fix_spurious_fault(vma, address); 3464 } 3465 unlock: 3466 pte_unmap_unlock(pte, ptl); 3467 return 0; 3468 } 3469 3470 /* 3471 * By the time we get here, we already hold the mm semaphore 3472 */ 3473 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3474 unsigned long address, unsigned int flags) 3475 { 3476 pgd_t *pgd; 3477 pud_t *pud; 3478 pmd_t *pmd; 3479 pte_t *pte; 3480 3481 __set_current_state(TASK_RUNNING); 3482 3483 count_vm_event(PGFAULT); 3484 mem_cgroup_count_vm_event(mm, PGFAULT); 3485 3486 /* do counter updates before entering really critical section. */ 3487 check_sync_rss_stat(current); 3488 3489 if (unlikely(is_vm_hugetlb_page(vma))) 3490 return hugetlb_fault(mm, vma, address, flags); 3491 3492 pgd = pgd_offset(mm, address); 3493 pud = pud_alloc(mm, pgd, address); 3494 if (!pud) 3495 return VM_FAULT_OOM; 3496 pmd = pmd_alloc(mm, pud, address); 3497 if (!pmd) 3498 return VM_FAULT_OOM; 3499 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { 3500 if (!vma->vm_ops) 3501 return do_huge_pmd_anonymous_page(mm, vma, address, 3502 pmd, flags); 3503 } else { 3504 pmd_t orig_pmd = *pmd; 3505 barrier(); 3506 if (pmd_trans_huge(orig_pmd)) { 3507 if (flags & FAULT_FLAG_WRITE && 3508 !pmd_write(orig_pmd) && 3509 !pmd_trans_splitting(orig_pmd)) 3510 return do_huge_pmd_wp_page(mm, vma, address, 3511 pmd, orig_pmd); 3512 return 0; 3513 } 3514 } 3515 3516 /* 3517 * Use __pte_alloc instead of pte_alloc_map, because we can't 3518 * run pte_offset_map on the pmd, if an huge pmd could 3519 * materialize from under us from a different thread. 3520 */ 3521 if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address)) 3522 return VM_FAULT_OOM; 3523 /* if an huge pmd materialized from under us just retry later */ 3524 if (unlikely(pmd_trans_huge(*pmd))) 3525 return 0; 3526 /* 3527 * A regular pmd is established and it can't morph into a huge pmd 3528 * from under us anymore at this point because we hold the mmap_sem 3529 * read mode and khugepaged takes it in write mode. So now it's 3530 * safe to run pte_offset_map(). 3531 */ 3532 pte = pte_offset_map(pmd, address); 3533 3534 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 3535 } 3536 3537 #ifndef __PAGETABLE_PUD_FOLDED 3538 /* 3539 * Allocate page upper directory. 3540 * We've already handled the fast-path in-line. 3541 */ 3542 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3543 { 3544 pud_t *new = pud_alloc_one(mm, address); 3545 if (!new) 3546 return -ENOMEM; 3547 3548 smp_wmb(); /* See comment in __pte_alloc */ 3549 3550 spin_lock(&mm->page_table_lock); 3551 if (pgd_present(*pgd)) /* Another has populated it */ 3552 pud_free(mm, new); 3553 else 3554 pgd_populate(mm, pgd, new); 3555 spin_unlock(&mm->page_table_lock); 3556 return 0; 3557 } 3558 #endif /* __PAGETABLE_PUD_FOLDED */ 3559 3560 #ifndef __PAGETABLE_PMD_FOLDED 3561 /* 3562 * Allocate page middle directory. 3563 * We've already handled the fast-path in-line. 3564 */ 3565 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 3566 { 3567 pmd_t *new = pmd_alloc_one(mm, address); 3568 if (!new) 3569 return -ENOMEM; 3570 3571 smp_wmb(); /* See comment in __pte_alloc */ 3572 3573 spin_lock(&mm->page_table_lock); 3574 #ifndef __ARCH_HAS_4LEVEL_HACK 3575 if (pud_present(*pud)) /* Another has populated it */ 3576 pmd_free(mm, new); 3577 else 3578 pud_populate(mm, pud, new); 3579 #else 3580 if (pgd_present(*pud)) /* Another has populated it */ 3581 pmd_free(mm, new); 3582 else 3583 pgd_populate(mm, pud, new); 3584 #endif /* __ARCH_HAS_4LEVEL_HACK */ 3585 spin_unlock(&mm->page_table_lock); 3586 return 0; 3587 } 3588 #endif /* __PAGETABLE_PMD_FOLDED */ 3589 3590 int make_pages_present(unsigned long addr, unsigned long end) 3591 { 3592 int ret, len, write; 3593 struct vm_area_struct * vma; 3594 3595 vma = find_vma(current->mm, addr); 3596 if (!vma) 3597 return -ENOMEM; 3598 /* 3599 * We want to touch writable mappings with a write fault in order 3600 * to break COW, except for shared mappings because these don't COW 3601 * and we would not want to dirty them for nothing. 3602 */ 3603 write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE; 3604 BUG_ON(addr >= end); 3605 BUG_ON(end > vma->vm_end); 3606 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; 3607 ret = get_user_pages(current, current->mm, addr, 3608 len, write, 0, NULL, NULL); 3609 if (ret < 0) 3610 return ret; 3611 return ret == len ? 0 : -EFAULT; 3612 } 3613 3614 #if !defined(__HAVE_ARCH_GATE_AREA) 3615 3616 #if defined(AT_SYSINFO_EHDR) 3617 static struct vm_area_struct gate_vma; 3618 3619 static int __init gate_vma_init(void) 3620 { 3621 gate_vma.vm_mm = NULL; 3622 gate_vma.vm_start = FIXADDR_USER_START; 3623 gate_vma.vm_end = FIXADDR_USER_END; 3624 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 3625 gate_vma.vm_page_prot = __P101; 3626 3627 return 0; 3628 } 3629 __initcall(gate_vma_init); 3630 #endif 3631 3632 struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 3633 { 3634 #ifdef AT_SYSINFO_EHDR 3635 return &gate_vma; 3636 #else 3637 return NULL; 3638 #endif 3639 } 3640 3641 int in_gate_area_no_mm(unsigned long addr) 3642 { 3643 #ifdef AT_SYSINFO_EHDR 3644 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 3645 return 1; 3646 #endif 3647 return 0; 3648 } 3649 3650 #endif /* __HAVE_ARCH_GATE_AREA */ 3651 3652 static int __follow_pte(struct mm_struct *mm, unsigned long address, 3653 pte_t **ptepp, spinlock_t **ptlp) 3654 { 3655 pgd_t *pgd; 3656 pud_t *pud; 3657 pmd_t *pmd; 3658 pte_t *ptep; 3659 3660 pgd = pgd_offset(mm, address); 3661 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 3662 goto out; 3663 3664 pud = pud_offset(pgd, address); 3665 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 3666 goto out; 3667 3668 pmd = pmd_offset(pud, address); 3669 VM_BUG_ON(pmd_trans_huge(*pmd)); 3670 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 3671 goto out; 3672 3673 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 3674 if (pmd_huge(*pmd)) 3675 goto out; 3676 3677 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 3678 if (!ptep) 3679 goto out; 3680 if (!pte_present(*ptep)) 3681 goto unlock; 3682 *ptepp = ptep; 3683 return 0; 3684 unlock: 3685 pte_unmap_unlock(ptep, *ptlp); 3686 out: 3687 return -EINVAL; 3688 } 3689 3690 static inline int follow_pte(struct mm_struct *mm, unsigned long address, 3691 pte_t **ptepp, spinlock_t **ptlp) 3692 { 3693 int res; 3694 3695 /* (void) is needed to make gcc happy */ 3696 (void) __cond_lock(*ptlp, 3697 !(res = __follow_pte(mm, address, ptepp, ptlp))); 3698 return res; 3699 } 3700 3701 /** 3702 * follow_pfn - look up PFN at a user virtual address 3703 * @vma: memory mapping 3704 * @address: user virtual address 3705 * @pfn: location to store found PFN 3706 * 3707 * Only IO mappings and raw PFN mappings are allowed. 3708 * 3709 * Returns zero and the pfn at @pfn on success, -ve otherwise. 3710 */ 3711 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 3712 unsigned long *pfn) 3713 { 3714 int ret = -EINVAL; 3715 spinlock_t *ptl; 3716 pte_t *ptep; 3717 3718 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3719 return ret; 3720 3721 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 3722 if (ret) 3723 return ret; 3724 *pfn = pte_pfn(*ptep); 3725 pte_unmap_unlock(ptep, ptl); 3726 return 0; 3727 } 3728 EXPORT_SYMBOL(follow_pfn); 3729 3730 #ifdef CONFIG_HAVE_IOREMAP_PROT 3731 int follow_phys(struct vm_area_struct *vma, 3732 unsigned long address, unsigned int flags, 3733 unsigned long *prot, resource_size_t *phys) 3734 { 3735 int ret = -EINVAL; 3736 pte_t *ptep, pte; 3737 spinlock_t *ptl; 3738 3739 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3740 goto out; 3741 3742 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 3743 goto out; 3744 pte = *ptep; 3745 3746 if ((flags & FOLL_WRITE) && !pte_write(pte)) 3747 goto unlock; 3748 3749 *prot = pgprot_val(pte_pgprot(pte)); 3750 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 3751 3752 ret = 0; 3753 unlock: 3754 pte_unmap_unlock(ptep, ptl); 3755 out: 3756 return ret; 3757 } 3758 3759 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 3760 void *buf, int len, int write) 3761 { 3762 resource_size_t phys_addr; 3763 unsigned long prot = 0; 3764 void __iomem *maddr; 3765 int offset = addr & (PAGE_SIZE-1); 3766 3767 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 3768 return -EINVAL; 3769 3770 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 3771 if (write) 3772 memcpy_toio(maddr + offset, buf, len); 3773 else 3774 memcpy_fromio(buf, maddr + offset, len); 3775 iounmap(maddr); 3776 3777 return len; 3778 } 3779 #endif 3780 3781 /* 3782 * Access another process' address space as given in mm. If non-NULL, use the 3783 * given task for page fault accounting. 3784 */ 3785 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 3786 unsigned long addr, void *buf, int len, int write) 3787 { 3788 struct vm_area_struct *vma; 3789 void *old_buf = buf; 3790 3791 down_read(&mm->mmap_sem); 3792 /* ignore errors, just check how much was successfully transferred */ 3793 while (len) { 3794 int bytes, ret, offset; 3795 void *maddr; 3796 struct page *page = NULL; 3797 3798 ret = get_user_pages(tsk, mm, addr, 1, 3799 write, 1, &page, &vma); 3800 if (ret <= 0) { 3801 /* 3802 * Check if this is a VM_IO | VM_PFNMAP VMA, which 3803 * we can access using slightly different code. 3804 */ 3805 #ifdef CONFIG_HAVE_IOREMAP_PROT 3806 vma = find_vma(mm, addr); 3807 if (!vma || vma->vm_start > addr) 3808 break; 3809 if (vma->vm_ops && vma->vm_ops->access) 3810 ret = vma->vm_ops->access(vma, addr, buf, 3811 len, write); 3812 if (ret <= 0) 3813 #endif 3814 break; 3815 bytes = ret; 3816 } else { 3817 bytes = len; 3818 offset = addr & (PAGE_SIZE-1); 3819 if (bytes > PAGE_SIZE-offset) 3820 bytes = PAGE_SIZE-offset; 3821 3822 maddr = kmap(page); 3823 if (write) { 3824 copy_to_user_page(vma, page, addr, 3825 maddr + offset, buf, bytes); 3826 set_page_dirty_lock(page); 3827 } else { 3828 copy_from_user_page(vma, page, addr, 3829 buf, maddr + offset, bytes); 3830 } 3831 kunmap(page); 3832 page_cache_release(page); 3833 } 3834 len -= bytes; 3835 buf += bytes; 3836 addr += bytes; 3837 } 3838 up_read(&mm->mmap_sem); 3839 3840 return buf - old_buf; 3841 } 3842 3843 /** 3844 * access_remote_vm - access another process' address space 3845 * @mm: the mm_struct of the target address space 3846 * @addr: start address to access 3847 * @buf: source or destination buffer 3848 * @len: number of bytes to transfer 3849 * @write: whether the access is a write 3850 * 3851 * The caller must hold a reference on @mm. 3852 */ 3853 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 3854 void *buf, int len, int write) 3855 { 3856 return __access_remote_vm(NULL, mm, addr, buf, len, write); 3857 } 3858 3859 /* 3860 * Access another process' address space. 3861 * Source/target buffer must be kernel space, 3862 * Do not walk the page table directly, use get_user_pages 3863 */ 3864 int access_process_vm(struct task_struct *tsk, unsigned long addr, 3865 void *buf, int len, int write) 3866 { 3867 struct mm_struct *mm; 3868 int ret; 3869 3870 mm = get_task_mm(tsk); 3871 if (!mm) 3872 return 0; 3873 3874 ret = __access_remote_vm(tsk, mm, addr, buf, len, write); 3875 mmput(mm); 3876 3877 return ret; 3878 } 3879 3880 /* 3881 * Print the name of a VMA. 3882 */ 3883 void print_vma_addr(char *prefix, unsigned long ip) 3884 { 3885 struct mm_struct *mm = current->mm; 3886 struct vm_area_struct *vma; 3887 3888 /* 3889 * Do not print if we are in atomic 3890 * contexts (in exception stacks, etc.): 3891 */ 3892 if (preempt_count()) 3893 return; 3894 3895 down_read(&mm->mmap_sem); 3896 vma = find_vma(mm, ip); 3897 if (vma && vma->vm_file) { 3898 struct file *f = vma->vm_file; 3899 char *buf = (char *)__get_free_page(GFP_KERNEL); 3900 if (buf) { 3901 char *p, *s; 3902 3903 p = d_path(&f->f_path, buf, PAGE_SIZE); 3904 if (IS_ERR(p)) 3905 p = "?"; 3906 s = strrchr(p, '/'); 3907 if (s) 3908 p = s+1; 3909 printk("%s%s[%lx+%lx]", prefix, p, 3910 vma->vm_start, 3911 vma->vm_end - vma->vm_start); 3912 free_page((unsigned long)buf); 3913 } 3914 } 3915 up_read(¤t->mm->mmap_sem); 3916 } 3917 3918 #ifdef CONFIG_PROVE_LOCKING 3919 void might_fault(void) 3920 { 3921 /* 3922 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 3923 * holding the mmap_sem, this is safe because kernel memory doesn't 3924 * get paged out, therefore we'll never actually fault, and the 3925 * below annotations will generate false positives. 3926 */ 3927 if (segment_eq(get_fs(), KERNEL_DS)) 3928 return; 3929 3930 might_sleep(); 3931 /* 3932 * it would be nicer only to annotate paths which are not under 3933 * pagefault_disable, however that requires a larger audit and 3934 * providing helpers like get_user_atomic. 3935 */ 3936 if (!in_atomic() && current->mm) 3937 might_lock_read(¤t->mm->mmap_sem); 3938 } 3939 EXPORT_SYMBOL(might_fault); 3940 #endif 3941 3942 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 3943 static void clear_gigantic_page(struct page *page, 3944 unsigned long addr, 3945 unsigned int pages_per_huge_page) 3946 { 3947 int i; 3948 struct page *p = page; 3949 3950 might_sleep(); 3951 for (i = 0; i < pages_per_huge_page; 3952 i++, p = mem_map_next(p, page, i)) { 3953 cond_resched(); 3954 clear_user_highpage(p, addr + i * PAGE_SIZE); 3955 } 3956 } 3957 void clear_huge_page(struct page *page, 3958 unsigned long addr, unsigned int pages_per_huge_page) 3959 { 3960 int i; 3961 3962 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 3963 clear_gigantic_page(page, addr, pages_per_huge_page); 3964 return; 3965 } 3966 3967 might_sleep(); 3968 for (i = 0; i < pages_per_huge_page; i++) { 3969 cond_resched(); 3970 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 3971 } 3972 } 3973 3974 static void copy_user_gigantic_page(struct page *dst, struct page *src, 3975 unsigned long addr, 3976 struct vm_area_struct *vma, 3977 unsigned int pages_per_huge_page) 3978 { 3979 int i; 3980 struct page *dst_base = dst; 3981 struct page *src_base = src; 3982 3983 for (i = 0; i < pages_per_huge_page; ) { 3984 cond_resched(); 3985 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 3986 3987 i++; 3988 dst = mem_map_next(dst, dst_base, i); 3989 src = mem_map_next(src, src_base, i); 3990 } 3991 } 3992 3993 void copy_user_huge_page(struct page *dst, struct page *src, 3994 unsigned long addr, struct vm_area_struct *vma, 3995 unsigned int pages_per_huge_page) 3996 { 3997 int i; 3998 3999 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4000 copy_user_gigantic_page(dst, src, addr, vma, 4001 pages_per_huge_page); 4002 return; 4003 } 4004 4005 might_sleep(); 4006 for (i = 0; i < pages_per_huge_page; i++) { 4007 cond_resched(); 4008 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 4009 } 4010 } 4011 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 4012