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