1 /* 2 * linux/mm/memory.c 3 * 4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 5 */ 6 7 /* 8 * demand-loading started 01.12.91 - seems it is high on the list of 9 * things wanted, and it should be easy to implement. - Linus 10 */ 11 12 /* 13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared 14 * pages started 02.12.91, seems to work. - Linus. 15 * 16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it 17 * would have taken more than the 6M I have free, but it worked well as 18 * far as I could see. 19 * 20 * Also corrected some "invalidate()"s - I wasn't doing enough of them. 21 */ 22 23 /* 24 * Real VM (paging to/from disk) started 18.12.91. Much more work and 25 * thought has to go into this. Oh, well.. 26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. 27 * Found it. Everything seems to work now. 28 * 20.12.91 - Ok, making the swap-device changeable like the root. 29 */ 30 31 /* 32 * 05.04.94 - Multi-page memory management added for v1.1. 33 * Idea by Alex Bligh (alex@cconcepts.co.uk) 34 * 35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG 36 * (Gerhard.Wichert@pdb.siemens.de) 37 * 38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) 39 */ 40 41 #include <linux/kernel_stat.h> 42 #include <linux/mm.h> 43 #include <linux/hugetlb.h> 44 #include <linux/mman.h> 45 #include <linux/swap.h> 46 #include <linux/highmem.h> 47 #include <linux/pagemap.h> 48 #include <linux/ksm.h> 49 #include <linux/rmap.h> 50 #include <linux/export.h> 51 #include <linux/delayacct.h> 52 #include <linux/init.h> 53 #include <linux/writeback.h> 54 #include <linux/memcontrol.h> 55 #include <linux/mmu_notifier.h> 56 #include <linux/kallsyms.h> 57 #include <linux/swapops.h> 58 #include <linux/elf.h> 59 #include <linux/gfp.h> 60 #include <linux/migrate.h> 61 #include <linux/string.h> 62 63 #include <asm/io.h> 64 #include <asm/pgalloc.h> 65 #include <asm/uaccess.h> 66 #include <asm/tlb.h> 67 #include <asm/tlbflush.h> 68 #include <asm/pgtable.h> 69 70 #include "internal.h" 71 72 #ifdef LAST_NID_NOT_IN_PAGE_FLAGS 73 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_nid. 74 #endif 75 76 #ifndef CONFIG_NEED_MULTIPLE_NODES 77 /* use the per-pgdat data instead for discontigmem - mbligh */ 78 unsigned long max_mapnr; 79 struct page *mem_map; 80 81 EXPORT_SYMBOL(max_mapnr); 82 EXPORT_SYMBOL(mem_map); 83 #endif 84 85 unsigned long num_physpages; 86 /* 87 * A number of key systems in x86 including ioremap() rely on the assumption 88 * that high_memory defines the upper bound on direct map memory, then end 89 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 90 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 91 * and ZONE_HIGHMEM. 92 */ 93 void * high_memory; 94 95 EXPORT_SYMBOL(num_physpages); 96 EXPORT_SYMBOL(high_memory); 97 98 /* 99 * Randomize the address space (stacks, mmaps, brk, etc.). 100 * 101 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 102 * as ancient (libc5 based) binaries can segfault. ) 103 */ 104 int randomize_va_space __read_mostly = 105 #ifdef CONFIG_COMPAT_BRK 106 1; 107 #else 108 2; 109 #endif 110 111 static int __init disable_randmaps(char *s) 112 { 113 randomize_va_space = 0; 114 return 1; 115 } 116 __setup("norandmaps", disable_randmaps); 117 118 unsigned long zero_pfn __read_mostly; 119 unsigned long highest_memmap_pfn __read_mostly; 120 121 /* 122 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 123 */ 124 static int __init init_zero_pfn(void) 125 { 126 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 127 return 0; 128 } 129 core_initcall(init_zero_pfn); 130 131 132 #if defined(SPLIT_RSS_COUNTING) 133 134 void sync_mm_rss(struct mm_struct *mm) 135 { 136 int i; 137 138 for (i = 0; i < NR_MM_COUNTERS; i++) { 139 if (current->rss_stat.count[i]) { 140 add_mm_counter(mm, i, current->rss_stat.count[i]); 141 current->rss_stat.count[i] = 0; 142 } 143 } 144 current->rss_stat.events = 0; 145 } 146 147 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 148 { 149 struct task_struct *task = current; 150 151 if (likely(task->mm == mm)) 152 task->rss_stat.count[member] += val; 153 else 154 add_mm_counter(mm, member, val); 155 } 156 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 157 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 158 159 /* sync counter once per 64 page faults */ 160 #define TASK_RSS_EVENTS_THRESH (64) 161 static void check_sync_rss_stat(struct task_struct *task) 162 { 163 if (unlikely(task != current)) 164 return; 165 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 166 sync_mm_rss(task->mm); 167 } 168 #else /* SPLIT_RSS_COUNTING */ 169 170 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 171 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 172 173 static void check_sync_rss_stat(struct task_struct *task) 174 { 175 } 176 177 #endif /* SPLIT_RSS_COUNTING */ 178 179 #ifdef HAVE_GENERIC_MMU_GATHER 180 181 static int tlb_next_batch(struct mmu_gather *tlb) 182 { 183 struct mmu_gather_batch *batch; 184 185 batch = tlb->active; 186 if (batch->next) { 187 tlb->active = batch->next; 188 return 1; 189 } 190 191 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) 192 return 0; 193 194 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 195 if (!batch) 196 return 0; 197 198 tlb->batch_count++; 199 batch->next = NULL; 200 batch->nr = 0; 201 batch->max = MAX_GATHER_BATCH; 202 203 tlb->active->next = batch; 204 tlb->active = batch; 205 206 return 1; 207 } 208 209 /* tlb_gather_mmu 210 * Called to initialize an (on-stack) mmu_gather structure for page-table 211 * tear-down from @mm. The @fullmm argument is used when @mm is without 212 * users and we're going to destroy the full address space (exit/execve). 213 */ 214 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm) 215 { 216 tlb->mm = mm; 217 218 tlb->fullmm = fullmm; 219 tlb->need_flush_all = 0; 220 tlb->start = -1UL; 221 tlb->end = 0; 222 tlb->need_flush = 0; 223 tlb->fast_mode = (num_possible_cpus() == 1); 224 tlb->local.next = NULL; 225 tlb->local.nr = 0; 226 tlb->local.max = ARRAY_SIZE(tlb->__pages); 227 tlb->active = &tlb->local; 228 tlb->batch_count = 0; 229 230 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 231 tlb->batch = NULL; 232 #endif 233 } 234 235 void tlb_flush_mmu(struct mmu_gather *tlb) 236 { 237 struct mmu_gather_batch *batch; 238 239 if (!tlb->need_flush) 240 return; 241 tlb->need_flush = 0; 242 tlb_flush(tlb); 243 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 244 tlb_table_flush(tlb); 245 #endif 246 247 if (tlb_fast_mode(tlb)) 248 return; 249 250 for (batch = &tlb->local; batch; batch = batch->next) { 251 free_pages_and_swap_cache(batch->pages, batch->nr); 252 batch->nr = 0; 253 } 254 tlb->active = &tlb->local; 255 } 256 257 /* tlb_finish_mmu 258 * Called at the end of the shootdown operation to free up any resources 259 * that were required. 260 */ 261 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 262 { 263 struct mmu_gather_batch *batch, *next; 264 265 tlb->start = start; 266 tlb->end = end; 267 tlb_flush_mmu(tlb); 268 269 /* keep the page table cache within bounds */ 270 check_pgt_cache(); 271 272 for (batch = tlb->local.next; batch; batch = next) { 273 next = batch->next; 274 free_pages((unsigned long)batch, 0); 275 } 276 tlb->local.next = NULL; 277 } 278 279 /* __tlb_remove_page 280 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 281 * handling the additional races in SMP caused by other CPUs caching valid 282 * mappings in their TLBs. Returns the number of free page slots left. 283 * When out of page slots we must call tlb_flush_mmu(). 284 */ 285 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) 286 { 287 struct mmu_gather_batch *batch; 288 289 VM_BUG_ON(!tlb->need_flush); 290 291 if (tlb_fast_mode(tlb)) { 292 free_page_and_swap_cache(page); 293 return 1; /* avoid calling tlb_flush_mmu() */ 294 } 295 296 batch = tlb->active; 297 batch->pages[batch->nr++] = page; 298 if (batch->nr == batch->max) { 299 if (!tlb_next_batch(tlb)) 300 return 0; 301 batch = tlb->active; 302 } 303 VM_BUG_ON(batch->nr > batch->max); 304 305 return batch->max - batch->nr; 306 } 307 308 #endif /* HAVE_GENERIC_MMU_GATHER */ 309 310 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 311 312 /* 313 * See the comment near struct mmu_table_batch. 314 */ 315 316 static void tlb_remove_table_smp_sync(void *arg) 317 { 318 /* Simply deliver the interrupt */ 319 } 320 321 static void tlb_remove_table_one(void *table) 322 { 323 /* 324 * This isn't an RCU grace period and hence the page-tables cannot be 325 * assumed to be actually RCU-freed. 326 * 327 * It is however sufficient for software page-table walkers that rely on 328 * IRQ disabling. See the comment near struct mmu_table_batch. 329 */ 330 smp_call_function(tlb_remove_table_smp_sync, NULL, 1); 331 __tlb_remove_table(table); 332 } 333 334 static void tlb_remove_table_rcu(struct rcu_head *head) 335 { 336 struct mmu_table_batch *batch; 337 int i; 338 339 batch = container_of(head, struct mmu_table_batch, rcu); 340 341 for (i = 0; i < batch->nr; i++) 342 __tlb_remove_table(batch->tables[i]); 343 344 free_page((unsigned long)batch); 345 } 346 347 void tlb_table_flush(struct mmu_gather *tlb) 348 { 349 struct mmu_table_batch **batch = &tlb->batch; 350 351 if (*batch) { 352 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); 353 *batch = NULL; 354 } 355 } 356 357 void tlb_remove_table(struct mmu_gather *tlb, void *table) 358 { 359 struct mmu_table_batch **batch = &tlb->batch; 360 361 tlb->need_flush = 1; 362 363 /* 364 * When there's less then two users of this mm there cannot be a 365 * concurrent page-table walk. 366 */ 367 if (atomic_read(&tlb->mm->mm_users) < 2) { 368 __tlb_remove_table(table); 369 return; 370 } 371 372 if (*batch == NULL) { 373 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); 374 if (*batch == NULL) { 375 tlb_remove_table_one(table); 376 return; 377 } 378 (*batch)->nr = 0; 379 } 380 (*batch)->tables[(*batch)->nr++] = table; 381 if ((*batch)->nr == MAX_TABLE_BATCH) 382 tlb_table_flush(tlb); 383 } 384 385 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ 386 387 /* 388 * If a p?d_bad entry is found while walking page tables, report 389 * the error, before resetting entry to p?d_none. Usually (but 390 * very seldom) called out from the p?d_none_or_clear_bad macros. 391 */ 392 393 void pgd_clear_bad(pgd_t *pgd) 394 { 395 pgd_ERROR(*pgd); 396 pgd_clear(pgd); 397 } 398 399 void pud_clear_bad(pud_t *pud) 400 { 401 pud_ERROR(*pud); 402 pud_clear(pud); 403 } 404 405 void pmd_clear_bad(pmd_t *pmd) 406 { 407 pmd_ERROR(*pmd); 408 pmd_clear(pmd); 409 } 410 411 /* 412 * Note: this doesn't free the actual pages themselves. That 413 * has been handled earlier when unmapping all the memory regions. 414 */ 415 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 416 unsigned long addr) 417 { 418 pgtable_t token = pmd_pgtable(*pmd); 419 pmd_clear(pmd); 420 pte_free_tlb(tlb, token, addr); 421 tlb->mm->nr_ptes--; 422 } 423 424 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 425 unsigned long addr, unsigned long end, 426 unsigned long floor, unsigned long ceiling) 427 { 428 pmd_t *pmd; 429 unsigned long next; 430 unsigned long start; 431 432 start = addr; 433 pmd = pmd_offset(pud, addr); 434 do { 435 next = pmd_addr_end(addr, end); 436 if (pmd_none_or_clear_bad(pmd)) 437 continue; 438 free_pte_range(tlb, pmd, addr); 439 } while (pmd++, addr = next, addr != end); 440 441 start &= PUD_MASK; 442 if (start < floor) 443 return; 444 if (ceiling) { 445 ceiling &= PUD_MASK; 446 if (!ceiling) 447 return; 448 } 449 if (end - 1 > ceiling - 1) 450 return; 451 452 pmd = pmd_offset(pud, start); 453 pud_clear(pud); 454 pmd_free_tlb(tlb, pmd, start); 455 } 456 457 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 458 unsigned long addr, unsigned long end, 459 unsigned long floor, unsigned long ceiling) 460 { 461 pud_t *pud; 462 unsigned long next; 463 unsigned long start; 464 465 start = addr; 466 pud = pud_offset(pgd, addr); 467 do { 468 next = pud_addr_end(addr, end); 469 if (pud_none_or_clear_bad(pud)) 470 continue; 471 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 472 } while (pud++, addr = next, addr != end); 473 474 start &= PGDIR_MASK; 475 if (start < floor) 476 return; 477 if (ceiling) { 478 ceiling &= PGDIR_MASK; 479 if (!ceiling) 480 return; 481 } 482 if (end - 1 > ceiling - 1) 483 return; 484 485 pud = pud_offset(pgd, start); 486 pgd_clear(pgd); 487 pud_free_tlb(tlb, pud, start); 488 } 489 490 /* 491 * This function frees user-level page tables of a process. 492 * 493 * Must be called with pagetable lock held. 494 */ 495 void free_pgd_range(struct mmu_gather *tlb, 496 unsigned long addr, unsigned long end, 497 unsigned long floor, unsigned long ceiling) 498 { 499 pgd_t *pgd; 500 unsigned long next; 501 502 /* 503 * The next few lines have given us lots of grief... 504 * 505 * Why are we testing PMD* at this top level? Because often 506 * there will be no work to do at all, and we'd prefer not to 507 * go all the way down to the bottom just to discover that. 508 * 509 * Why all these "- 1"s? Because 0 represents both the bottom 510 * of the address space and the top of it (using -1 for the 511 * top wouldn't help much: the masks would do the wrong thing). 512 * The rule is that addr 0 and floor 0 refer to the bottom of 513 * the address space, but end 0 and ceiling 0 refer to the top 514 * Comparisons need to use "end - 1" and "ceiling - 1" (though 515 * that end 0 case should be mythical). 516 * 517 * Wherever addr is brought up or ceiling brought down, we must 518 * be careful to reject "the opposite 0" before it confuses the 519 * subsequent tests. But what about where end is brought down 520 * by PMD_SIZE below? no, end can't go down to 0 there. 521 * 522 * Whereas we round start (addr) and ceiling down, by different 523 * masks at different levels, in order to test whether a table 524 * now has no other vmas using it, so can be freed, we don't 525 * bother to round floor or end up - the tests don't need that. 526 */ 527 528 addr &= PMD_MASK; 529 if (addr < floor) { 530 addr += PMD_SIZE; 531 if (!addr) 532 return; 533 } 534 if (ceiling) { 535 ceiling &= PMD_MASK; 536 if (!ceiling) 537 return; 538 } 539 if (end - 1 > ceiling - 1) 540 end -= PMD_SIZE; 541 if (addr > end - 1) 542 return; 543 544 pgd = pgd_offset(tlb->mm, addr); 545 do { 546 next = pgd_addr_end(addr, end); 547 if (pgd_none_or_clear_bad(pgd)) 548 continue; 549 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 550 } while (pgd++, addr = next, addr != end); 551 } 552 553 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 554 unsigned long floor, unsigned long ceiling) 555 { 556 while (vma) { 557 struct vm_area_struct *next = vma->vm_next; 558 unsigned long addr = vma->vm_start; 559 560 /* 561 * Hide vma from rmap and truncate_pagecache before freeing 562 * pgtables 563 */ 564 unlink_anon_vmas(vma); 565 unlink_file_vma(vma); 566 567 if (is_vm_hugetlb_page(vma)) { 568 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 569 floor, next? next->vm_start: ceiling); 570 } else { 571 /* 572 * Optimization: gather nearby vmas into one call down 573 */ 574 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 575 && !is_vm_hugetlb_page(next)) { 576 vma = next; 577 next = vma->vm_next; 578 unlink_anon_vmas(vma); 579 unlink_file_vma(vma); 580 } 581 free_pgd_range(tlb, addr, vma->vm_end, 582 floor, next? next->vm_start: ceiling); 583 } 584 vma = next; 585 } 586 } 587 588 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, 589 pmd_t *pmd, unsigned long address) 590 { 591 pgtable_t new = pte_alloc_one(mm, address); 592 int wait_split_huge_page; 593 if (!new) 594 return -ENOMEM; 595 596 /* 597 * Ensure all pte setup (eg. pte page lock and page clearing) are 598 * visible before the pte is made visible to other CPUs by being 599 * put into page tables. 600 * 601 * The other side of the story is the pointer chasing in the page 602 * table walking code (when walking the page table without locking; 603 * ie. most of the time). Fortunately, these data accesses consist 604 * of a chain of data-dependent loads, meaning most CPUs (alpha 605 * being the notable exception) will already guarantee loads are 606 * seen in-order. See the alpha page table accessors for the 607 * smp_read_barrier_depends() barriers in page table walking code. 608 */ 609 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 610 611 spin_lock(&mm->page_table_lock); 612 wait_split_huge_page = 0; 613 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 614 mm->nr_ptes++; 615 pmd_populate(mm, pmd, new); 616 new = NULL; 617 } else if (unlikely(pmd_trans_splitting(*pmd))) 618 wait_split_huge_page = 1; 619 spin_unlock(&mm->page_table_lock); 620 if (new) 621 pte_free(mm, new); 622 if (wait_split_huge_page) 623 wait_split_huge_page(vma->anon_vma, pmd); 624 return 0; 625 } 626 627 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 628 { 629 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 630 if (!new) 631 return -ENOMEM; 632 633 smp_wmb(); /* See comment in __pte_alloc */ 634 635 spin_lock(&init_mm.page_table_lock); 636 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 637 pmd_populate_kernel(&init_mm, pmd, new); 638 new = NULL; 639 } else 640 VM_BUG_ON(pmd_trans_splitting(*pmd)); 641 spin_unlock(&init_mm.page_table_lock); 642 if (new) 643 pte_free_kernel(&init_mm, new); 644 return 0; 645 } 646 647 static inline void init_rss_vec(int *rss) 648 { 649 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 650 } 651 652 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 653 { 654 int i; 655 656 if (current->mm == mm) 657 sync_mm_rss(mm); 658 for (i = 0; i < NR_MM_COUNTERS; i++) 659 if (rss[i]) 660 add_mm_counter(mm, i, rss[i]); 661 } 662 663 /* 664 * This function is called to print an error when a bad pte 665 * is found. For example, we might have a PFN-mapped pte in 666 * a region that doesn't allow it. 667 * 668 * The calling function must still handle the error. 669 */ 670 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 671 pte_t pte, struct page *page) 672 { 673 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 674 pud_t *pud = pud_offset(pgd, addr); 675 pmd_t *pmd = pmd_offset(pud, addr); 676 struct address_space *mapping; 677 pgoff_t index; 678 static unsigned long resume; 679 static unsigned long nr_shown; 680 static unsigned long nr_unshown; 681 682 /* 683 * Allow a burst of 60 reports, then keep quiet for that minute; 684 * or allow a steady drip of one report per second. 685 */ 686 if (nr_shown == 60) { 687 if (time_before(jiffies, resume)) { 688 nr_unshown++; 689 return; 690 } 691 if (nr_unshown) { 692 printk(KERN_ALERT 693 "BUG: Bad page map: %lu messages suppressed\n", 694 nr_unshown); 695 nr_unshown = 0; 696 } 697 nr_shown = 0; 698 } 699 if (nr_shown++ == 0) 700 resume = jiffies + 60 * HZ; 701 702 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 703 index = linear_page_index(vma, addr); 704 705 printk(KERN_ALERT 706 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 707 current->comm, 708 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 709 if (page) 710 dump_page(page); 711 printk(KERN_ALERT 712 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 713 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 714 /* 715 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 716 */ 717 if (vma->vm_ops) 718 printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n", 719 vma->vm_ops->fault); 720 if (vma->vm_file && vma->vm_file->f_op) 721 printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n", 722 vma->vm_file->f_op->mmap); 723 dump_stack(); 724 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); 725 } 726 727 static inline bool is_cow_mapping(vm_flags_t flags) 728 { 729 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 730 } 731 732 /* 733 * vm_normal_page -- This function gets the "struct page" associated with a pte. 734 * 735 * "Special" mappings do not wish to be associated with a "struct page" (either 736 * it doesn't exist, or it exists but they don't want to touch it). In this 737 * case, NULL is returned here. "Normal" mappings do have a struct page. 738 * 739 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 740 * pte bit, in which case this function is trivial. Secondly, an architecture 741 * may not have a spare pte bit, which requires a more complicated scheme, 742 * described below. 743 * 744 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 745 * special mapping (even if there are underlying and valid "struct pages"). 746 * COWed pages of a VM_PFNMAP are always normal. 747 * 748 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 749 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 750 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 751 * mapping will always honor the rule 752 * 753 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 754 * 755 * And for normal mappings this is false. 756 * 757 * This restricts such mappings to be a linear translation from virtual address 758 * to pfn. To get around this restriction, we allow arbitrary mappings so long 759 * as the vma is not a COW mapping; in that case, we know that all ptes are 760 * special (because none can have been COWed). 761 * 762 * 763 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 764 * 765 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 766 * page" backing, however the difference is that _all_ pages with a struct 767 * page (that is, those where pfn_valid is true) are refcounted and considered 768 * normal pages by the VM. The disadvantage is that pages are refcounted 769 * (which can be slower and simply not an option for some PFNMAP users). The 770 * advantage is that we don't have to follow the strict linearity rule of 771 * PFNMAP mappings in order to support COWable mappings. 772 * 773 */ 774 #ifdef __HAVE_ARCH_PTE_SPECIAL 775 # define HAVE_PTE_SPECIAL 1 776 #else 777 # define HAVE_PTE_SPECIAL 0 778 #endif 779 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 780 pte_t pte) 781 { 782 unsigned long pfn = pte_pfn(pte); 783 784 if (HAVE_PTE_SPECIAL) { 785 if (likely(!pte_special(pte))) 786 goto check_pfn; 787 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 788 return NULL; 789 if (!is_zero_pfn(pfn)) 790 print_bad_pte(vma, addr, pte, NULL); 791 return NULL; 792 } 793 794 /* !HAVE_PTE_SPECIAL case follows: */ 795 796 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 797 if (vma->vm_flags & VM_MIXEDMAP) { 798 if (!pfn_valid(pfn)) 799 return NULL; 800 goto out; 801 } else { 802 unsigned long off; 803 off = (addr - vma->vm_start) >> PAGE_SHIFT; 804 if (pfn == vma->vm_pgoff + off) 805 return NULL; 806 if (!is_cow_mapping(vma->vm_flags)) 807 return NULL; 808 } 809 } 810 811 if (is_zero_pfn(pfn)) 812 return NULL; 813 check_pfn: 814 if (unlikely(pfn > highest_memmap_pfn)) { 815 print_bad_pte(vma, addr, pte, NULL); 816 return NULL; 817 } 818 819 /* 820 * NOTE! We still have PageReserved() pages in the page tables. 821 * eg. VDSO mappings can cause them to exist. 822 */ 823 out: 824 return pfn_to_page(pfn); 825 } 826 827 /* 828 * copy one vm_area from one task to the other. Assumes the page tables 829 * already present in the new task to be cleared in the whole range 830 * covered by this vma. 831 */ 832 833 static inline unsigned long 834 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 835 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 836 unsigned long addr, int *rss) 837 { 838 unsigned long vm_flags = vma->vm_flags; 839 pte_t pte = *src_pte; 840 struct page *page; 841 842 /* pte contains position in swap or file, so copy. */ 843 if (unlikely(!pte_present(pte))) { 844 if (!pte_file(pte)) { 845 swp_entry_t entry = pte_to_swp_entry(pte); 846 847 if (swap_duplicate(entry) < 0) 848 return entry.val; 849 850 /* make sure dst_mm is on swapoff's mmlist. */ 851 if (unlikely(list_empty(&dst_mm->mmlist))) { 852 spin_lock(&mmlist_lock); 853 if (list_empty(&dst_mm->mmlist)) 854 list_add(&dst_mm->mmlist, 855 &src_mm->mmlist); 856 spin_unlock(&mmlist_lock); 857 } 858 if (likely(!non_swap_entry(entry))) 859 rss[MM_SWAPENTS]++; 860 else if (is_migration_entry(entry)) { 861 page = migration_entry_to_page(entry); 862 863 if (PageAnon(page)) 864 rss[MM_ANONPAGES]++; 865 else 866 rss[MM_FILEPAGES]++; 867 868 if (is_write_migration_entry(entry) && 869 is_cow_mapping(vm_flags)) { 870 /* 871 * COW mappings require pages in both 872 * parent and child to be set to read. 873 */ 874 make_migration_entry_read(&entry); 875 pte = swp_entry_to_pte(entry); 876 set_pte_at(src_mm, addr, src_pte, pte); 877 } 878 } 879 } 880 goto out_set_pte; 881 } 882 883 /* 884 * If it's a COW mapping, write protect it both 885 * in the parent and the child 886 */ 887 if (is_cow_mapping(vm_flags)) { 888 ptep_set_wrprotect(src_mm, addr, src_pte); 889 pte = pte_wrprotect(pte); 890 } 891 892 /* 893 * If it's a shared mapping, mark it clean in 894 * the child 895 */ 896 if (vm_flags & VM_SHARED) 897 pte = pte_mkclean(pte); 898 pte = pte_mkold(pte); 899 900 page = vm_normal_page(vma, addr, pte); 901 if (page) { 902 get_page(page); 903 page_dup_rmap(page); 904 if (PageAnon(page)) 905 rss[MM_ANONPAGES]++; 906 else 907 rss[MM_FILEPAGES]++; 908 } 909 910 out_set_pte: 911 set_pte_at(dst_mm, addr, dst_pte, pte); 912 return 0; 913 } 914 915 int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 916 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 917 unsigned long addr, unsigned long end) 918 { 919 pte_t *orig_src_pte, *orig_dst_pte; 920 pte_t *src_pte, *dst_pte; 921 spinlock_t *src_ptl, *dst_ptl; 922 int progress = 0; 923 int rss[NR_MM_COUNTERS]; 924 swp_entry_t entry = (swp_entry_t){0}; 925 926 again: 927 init_rss_vec(rss); 928 929 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 930 if (!dst_pte) 931 return -ENOMEM; 932 src_pte = pte_offset_map(src_pmd, addr); 933 src_ptl = pte_lockptr(src_mm, src_pmd); 934 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 935 orig_src_pte = src_pte; 936 orig_dst_pte = dst_pte; 937 arch_enter_lazy_mmu_mode(); 938 939 do { 940 /* 941 * We are holding two locks at this point - either of them 942 * could generate latencies in another task on another CPU. 943 */ 944 if (progress >= 32) { 945 progress = 0; 946 if (need_resched() || 947 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 948 break; 949 } 950 if (pte_none(*src_pte)) { 951 progress++; 952 continue; 953 } 954 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 955 vma, addr, rss); 956 if (entry.val) 957 break; 958 progress += 8; 959 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 960 961 arch_leave_lazy_mmu_mode(); 962 spin_unlock(src_ptl); 963 pte_unmap(orig_src_pte); 964 add_mm_rss_vec(dst_mm, rss); 965 pte_unmap_unlock(orig_dst_pte, dst_ptl); 966 cond_resched(); 967 968 if (entry.val) { 969 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 970 return -ENOMEM; 971 progress = 0; 972 } 973 if (addr != end) 974 goto again; 975 return 0; 976 } 977 978 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 979 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 980 unsigned long addr, unsigned long end) 981 { 982 pmd_t *src_pmd, *dst_pmd; 983 unsigned long next; 984 985 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 986 if (!dst_pmd) 987 return -ENOMEM; 988 src_pmd = pmd_offset(src_pud, addr); 989 do { 990 next = pmd_addr_end(addr, end); 991 if (pmd_trans_huge(*src_pmd)) { 992 int err; 993 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); 994 err = copy_huge_pmd(dst_mm, src_mm, 995 dst_pmd, src_pmd, addr, vma); 996 if (err == -ENOMEM) 997 return -ENOMEM; 998 if (!err) 999 continue; 1000 /* fall through */ 1001 } 1002 if (pmd_none_or_clear_bad(src_pmd)) 1003 continue; 1004 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 1005 vma, addr, next)) 1006 return -ENOMEM; 1007 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 1008 return 0; 1009 } 1010 1011 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1012 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 1013 unsigned long addr, unsigned long end) 1014 { 1015 pud_t *src_pud, *dst_pud; 1016 unsigned long next; 1017 1018 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 1019 if (!dst_pud) 1020 return -ENOMEM; 1021 src_pud = pud_offset(src_pgd, addr); 1022 do { 1023 next = pud_addr_end(addr, end); 1024 if (pud_none_or_clear_bad(src_pud)) 1025 continue; 1026 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 1027 vma, addr, next)) 1028 return -ENOMEM; 1029 } while (dst_pud++, src_pud++, addr = next, addr != end); 1030 return 0; 1031 } 1032 1033 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1034 struct vm_area_struct *vma) 1035 { 1036 pgd_t *src_pgd, *dst_pgd; 1037 unsigned long next; 1038 unsigned long addr = vma->vm_start; 1039 unsigned long end = vma->vm_end; 1040 unsigned long mmun_start; /* For mmu_notifiers */ 1041 unsigned long mmun_end; /* For mmu_notifiers */ 1042 bool is_cow; 1043 int ret; 1044 1045 /* 1046 * Don't copy ptes where a page fault will fill them correctly. 1047 * Fork becomes much lighter when there are big shared or private 1048 * readonly mappings. The tradeoff is that copy_page_range is more 1049 * efficient than faulting. 1050 */ 1051 if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR | 1052 VM_PFNMAP | VM_MIXEDMAP))) { 1053 if (!vma->anon_vma) 1054 return 0; 1055 } 1056 1057 if (is_vm_hugetlb_page(vma)) 1058 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 1059 1060 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 1061 /* 1062 * We do not free on error cases below as remove_vma 1063 * gets called on error from higher level routine 1064 */ 1065 ret = track_pfn_copy(vma); 1066 if (ret) 1067 return ret; 1068 } 1069 1070 /* 1071 * We need to invalidate the secondary MMU mappings only when 1072 * there could be a permission downgrade on the ptes of the 1073 * parent mm. And a permission downgrade will only happen if 1074 * is_cow_mapping() returns true. 1075 */ 1076 is_cow = is_cow_mapping(vma->vm_flags); 1077 mmun_start = addr; 1078 mmun_end = end; 1079 if (is_cow) 1080 mmu_notifier_invalidate_range_start(src_mm, mmun_start, 1081 mmun_end); 1082 1083 ret = 0; 1084 dst_pgd = pgd_offset(dst_mm, addr); 1085 src_pgd = pgd_offset(src_mm, addr); 1086 do { 1087 next = pgd_addr_end(addr, end); 1088 if (pgd_none_or_clear_bad(src_pgd)) 1089 continue; 1090 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 1091 vma, addr, next))) { 1092 ret = -ENOMEM; 1093 break; 1094 } 1095 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1096 1097 if (is_cow) 1098 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); 1099 return ret; 1100 } 1101 1102 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1103 struct vm_area_struct *vma, pmd_t *pmd, 1104 unsigned long addr, unsigned long end, 1105 struct zap_details *details) 1106 { 1107 struct mm_struct *mm = tlb->mm; 1108 int force_flush = 0; 1109 int rss[NR_MM_COUNTERS]; 1110 spinlock_t *ptl; 1111 pte_t *start_pte; 1112 pte_t *pte; 1113 1114 again: 1115 init_rss_vec(rss); 1116 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1117 pte = start_pte; 1118 arch_enter_lazy_mmu_mode(); 1119 do { 1120 pte_t ptent = *pte; 1121 if (pte_none(ptent)) { 1122 continue; 1123 } 1124 1125 if (pte_present(ptent)) { 1126 struct page *page; 1127 1128 page = vm_normal_page(vma, addr, ptent); 1129 if (unlikely(details) && page) { 1130 /* 1131 * unmap_shared_mapping_pages() wants to 1132 * invalidate cache without truncating: 1133 * unmap shared but keep private pages. 1134 */ 1135 if (details->check_mapping && 1136 details->check_mapping != page->mapping) 1137 continue; 1138 /* 1139 * Each page->index must be checked when 1140 * invalidating or truncating nonlinear. 1141 */ 1142 if (details->nonlinear_vma && 1143 (page->index < details->first_index || 1144 page->index > details->last_index)) 1145 continue; 1146 } 1147 ptent = ptep_get_and_clear_full(mm, addr, pte, 1148 tlb->fullmm); 1149 tlb_remove_tlb_entry(tlb, pte, addr); 1150 if (unlikely(!page)) 1151 continue; 1152 if (unlikely(details) && details->nonlinear_vma 1153 && linear_page_index(details->nonlinear_vma, 1154 addr) != page->index) 1155 set_pte_at(mm, addr, pte, 1156 pgoff_to_pte(page->index)); 1157 if (PageAnon(page)) 1158 rss[MM_ANONPAGES]--; 1159 else { 1160 if (pte_dirty(ptent)) 1161 set_page_dirty(page); 1162 if (pte_young(ptent) && 1163 likely(!VM_SequentialReadHint(vma))) 1164 mark_page_accessed(page); 1165 rss[MM_FILEPAGES]--; 1166 } 1167 page_remove_rmap(page); 1168 if (unlikely(page_mapcount(page) < 0)) 1169 print_bad_pte(vma, addr, ptent, page); 1170 force_flush = !__tlb_remove_page(tlb, page); 1171 if (force_flush) 1172 break; 1173 continue; 1174 } 1175 /* 1176 * If details->check_mapping, we leave swap entries; 1177 * if details->nonlinear_vma, we leave file entries. 1178 */ 1179 if (unlikely(details)) 1180 continue; 1181 if (pte_file(ptent)) { 1182 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 1183 print_bad_pte(vma, addr, ptent, NULL); 1184 } else { 1185 swp_entry_t entry = pte_to_swp_entry(ptent); 1186 1187 if (!non_swap_entry(entry)) 1188 rss[MM_SWAPENTS]--; 1189 else if (is_migration_entry(entry)) { 1190 struct page *page; 1191 1192 page = migration_entry_to_page(entry); 1193 1194 if (PageAnon(page)) 1195 rss[MM_ANONPAGES]--; 1196 else 1197 rss[MM_FILEPAGES]--; 1198 } 1199 if (unlikely(!free_swap_and_cache(entry))) 1200 print_bad_pte(vma, addr, ptent, NULL); 1201 } 1202 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1203 } while (pte++, addr += PAGE_SIZE, addr != end); 1204 1205 add_mm_rss_vec(mm, rss); 1206 arch_leave_lazy_mmu_mode(); 1207 pte_unmap_unlock(start_pte, ptl); 1208 1209 /* 1210 * mmu_gather ran out of room to batch pages, we break out of 1211 * the PTE lock to avoid doing the potential expensive TLB invalidate 1212 * and page-free while holding it. 1213 */ 1214 if (force_flush) { 1215 force_flush = 0; 1216 1217 #ifdef HAVE_GENERIC_MMU_GATHER 1218 tlb->start = addr; 1219 tlb->end = end; 1220 #endif 1221 tlb_flush_mmu(tlb); 1222 if (addr != end) 1223 goto again; 1224 } 1225 1226 return addr; 1227 } 1228 1229 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1230 struct vm_area_struct *vma, pud_t *pud, 1231 unsigned long addr, unsigned long end, 1232 struct zap_details *details) 1233 { 1234 pmd_t *pmd; 1235 unsigned long next; 1236 1237 pmd = pmd_offset(pud, addr); 1238 do { 1239 next = pmd_addr_end(addr, end); 1240 if (pmd_trans_huge(*pmd)) { 1241 if (next - addr != HPAGE_PMD_SIZE) { 1242 #ifdef CONFIG_DEBUG_VM 1243 if (!rwsem_is_locked(&tlb->mm->mmap_sem)) { 1244 pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n", 1245 __func__, addr, end, 1246 vma->vm_start, 1247 vma->vm_end); 1248 BUG(); 1249 } 1250 #endif 1251 split_huge_page_pmd(vma, addr, pmd); 1252 } else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1253 goto next; 1254 /* fall through */ 1255 } 1256 /* 1257 * Here there can be other concurrent MADV_DONTNEED or 1258 * trans huge page faults running, and if the pmd is 1259 * none or trans huge it can change under us. This is 1260 * because MADV_DONTNEED holds the mmap_sem in read 1261 * mode. 1262 */ 1263 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1264 goto next; 1265 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1266 next: 1267 cond_resched(); 1268 } while (pmd++, addr = next, addr != end); 1269 1270 return addr; 1271 } 1272 1273 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1274 struct vm_area_struct *vma, pgd_t *pgd, 1275 unsigned long addr, unsigned long end, 1276 struct zap_details *details) 1277 { 1278 pud_t *pud; 1279 unsigned long next; 1280 1281 pud = pud_offset(pgd, addr); 1282 do { 1283 next = pud_addr_end(addr, end); 1284 if (pud_none_or_clear_bad(pud)) 1285 continue; 1286 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1287 } while (pud++, addr = next, addr != end); 1288 1289 return addr; 1290 } 1291 1292 static void unmap_page_range(struct mmu_gather *tlb, 1293 struct vm_area_struct *vma, 1294 unsigned long addr, unsigned long end, 1295 struct zap_details *details) 1296 { 1297 pgd_t *pgd; 1298 unsigned long next; 1299 1300 if (details && !details->check_mapping && !details->nonlinear_vma) 1301 details = NULL; 1302 1303 BUG_ON(addr >= end); 1304 mem_cgroup_uncharge_start(); 1305 tlb_start_vma(tlb, vma); 1306 pgd = pgd_offset(vma->vm_mm, addr); 1307 do { 1308 next = pgd_addr_end(addr, end); 1309 if (pgd_none_or_clear_bad(pgd)) 1310 continue; 1311 next = zap_pud_range(tlb, vma, pgd, addr, next, details); 1312 } while (pgd++, addr = next, addr != end); 1313 tlb_end_vma(tlb, vma); 1314 mem_cgroup_uncharge_end(); 1315 } 1316 1317 1318 static void unmap_single_vma(struct mmu_gather *tlb, 1319 struct vm_area_struct *vma, unsigned long start_addr, 1320 unsigned long end_addr, 1321 struct zap_details *details) 1322 { 1323 unsigned long start = max(vma->vm_start, start_addr); 1324 unsigned long end; 1325 1326 if (start >= vma->vm_end) 1327 return; 1328 end = min(vma->vm_end, end_addr); 1329 if (end <= vma->vm_start) 1330 return; 1331 1332 if (vma->vm_file) 1333 uprobe_munmap(vma, start, end); 1334 1335 if (unlikely(vma->vm_flags & VM_PFNMAP)) 1336 untrack_pfn(vma, 0, 0); 1337 1338 if (start != end) { 1339 if (unlikely(is_vm_hugetlb_page(vma))) { 1340 /* 1341 * It is undesirable to test vma->vm_file as it 1342 * should be non-null for valid hugetlb area. 1343 * However, vm_file will be NULL in the error 1344 * cleanup path of do_mmap_pgoff. When 1345 * hugetlbfs ->mmap method fails, 1346 * do_mmap_pgoff() nullifies vma->vm_file 1347 * before calling this function to clean up. 1348 * Since no pte has actually been setup, it is 1349 * safe to do nothing in this case. 1350 */ 1351 if (vma->vm_file) { 1352 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 1353 __unmap_hugepage_range_final(tlb, vma, start, end, NULL); 1354 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 1355 } 1356 } else 1357 unmap_page_range(tlb, vma, start, end, details); 1358 } 1359 } 1360 1361 /** 1362 * unmap_vmas - unmap a range of memory covered by a list of vma's 1363 * @tlb: address of the caller's struct mmu_gather 1364 * @vma: the starting vma 1365 * @start_addr: virtual address at which to start unmapping 1366 * @end_addr: virtual address at which to end unmapping 1367 * 1368 * Unmap all pages in the vma list. 1369 * 1370 * Only addresses between `start' and `end' will be unmapped. 1371 * 1372 * The VMA list must be sorted in ascending virtual address order. 1373 * 1374 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1375 * range after unmap_vmas() returns. So the only responsibility here is to 1376 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1377 * drops the lock and schedules. 1378 */ 1379 void unmap_vmas(struct mmu_gather *tlb, 1380 struct vm_area_struct *vma, unsigned long start_addr, 1381 unsigned long end_addr) 1382 { 1383 struct mm_struct *mm = vma->vm_mm; 1384 1385 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1386 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1387 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); 1388 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1389 } 1390 1391 /** 1392 * zap_page_range - remove user pages in a given range 1393 * @vma: vm_area_struct holding the applicable pages 1394 * @start: starting address of pages to zap 1395 * @size: number of bytes to zap 1396 * @details: details of nonlinear truncation or shared cache invalidation 1397 * 1398 * Caller must protect the VMA list 1399 */ 1400 void zap_page_range(struct vm_area_struct *vma, unsigned long start, 1401 unsigned long size, struct zap_details *details) 1402 { 1403 struct mm_struct *mm = vma->vm_mm; 1404 struct mmu_gather tlb; 1405 unsigned long end = start + size; 1406 1407 lru_add_drain(); 1408 tlb_gather_mmu(&tlb, mm, 0); 1409 update_hiwater_rss(mm); 1410 mmu_notifier_invalidate_range_start(mm, start, end); 1411 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) 1412 unmap_single_vma(&tlb, vma, start, end, details); 1413 mmu_notifier_invalidate_range_end(mm, start, end); 1414 tlb_finish_mmu(&tlb, start, end); 1415 } 1416 1417 /** 1418 * zap_page_range_single - remove user pages in a given range 1419 * @vma: vm_area_struct holding the applicable pages 1420 * @address: starting address of pages to zap 1421 * @size: number of bytes to zap 1422 * @details: details of nonlinear truncation or shared cache invalidation 1423 * 1424 * The range must fit into one VMA. 1425 */ 1426 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1427 unsigned long size, struct zap_details *details) 1428 { 1429 struct mm_struct *mm = vma->vm_mm; 1430 struct mmu_gather tlb; 1431 unsigned long end = address + size; 1432 1433 lru_add_drain(); 1434 tlb_gather_mmu(&tlb, mm, 0); 1435 update_hiwater_rss(mm); 1436 mmu_notifier_invalidate_range_start(mm, address, end); 1437 unmap_single_vma(&tlb, vma, address, end, details); 1438 mmu_notifier_invalidate_range_end(mm, address, end); 1439 tlb_finish_mmu(&tlb, address, end); 1440 } 1441 1442 /** 1443 * zap_vma_ptes - remove ptes mapping the vma 1444 * @vma: vm_area_struct holding ptes to be zapped 1445 * @address: starting address of pages to zap 1446 * @size: number of bytes to zap 1447 * 1448 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1449 * 1450 * The entire address range must be fully contained within the vma. 1451 * 1452 * Returns 0 if successful. 1453 */ 1454 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1455 unsigned long size) 1456 { 1457 if (address < vma->vm_start || address + size > vma->vm_end || 1458 !(vma->vm_flags & VM_PFNMAP)) 1459 return -1; 1460 zap_page_range_single(vma, address, size, NULL); 1461 return 0; 1462 } 1463 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1464 1465 /** 1466 * follow_page_mask - look up a page descriptor from a user-virtual address 1467 * @vma: vm_area_struct mapping @address 1468 * @address: virtual address to look up 1469 * @flags: flags modifying lookup behaviour 1470 * @page_mask: on output, *page_mask is set according to the size of the page 1471 * 1472 * @flags can have FOLL_ flags set, defined in <linux/mm.h> 1473 * 1474 * Returns the mapped (struct page *), %NULL if no mapping exists, or 1475 * an error pointer if there is a mapping to something not represented 1476 * by a page descriptor (see also vm_normal_page()). 1477 */ 1478 struct page *follow_page_mask(struct vm_area_struct *vma, 1479 unsigned long address, unsigned int flags, 1480 unsigned int *page_mask) 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_mask = 0; 1491 1492 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 1493 if (!IS_ERR(page)) { 1494 BUG_ON(flags & FOLL_GET); 1495 goto out; 1496 } 1497 1498 page = NULL; 1499 pgd = pgd_offset(mm, address); 1500 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 1501 goto no_page_table; 1502 1503 pud = pud_offset(pgd, address); 1504 if (pud_none(*pud)) 1505 goto no_page_table; 1506 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { 1507 BUG_ON(flags & FOLL_GET); 1508 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); 1509 goto out; 1510 } 1511 if (unlikely(pud_bad(*pud))) 1512 goto no_page_table; 1513 1514 pmd = pmd_offset(pud, address); 1515 if (pmd_none(*pmd)) 1516 goto no_page_table; 1517 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) { 1518 BUG_ON(flags & FOLL_GET); 1519 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 1520 goto out; 1521 } 1522 if ((flags & FOLL_NUMA) && pmd_numa(*pmd)) 1523 goto no_page_table; 1524 if (pmd_trans_huge(*pmd)) { 1525 if (flags & FOLL_SPLIT) { 1526 split_huge_page_pmd(vma, address, pmd); 1527 goto split_fallthrough; 1528 } 1529 spin_lock(&mm->page_table_lock); 1530 if (likely(pmd_trans_huge(*pmd))) { 1531 if (unlikely(pmd_trans_splitting(*pmd))) { 1532 spin_unlock(&mm->page_table_lock); 1533 wait_split_huge_page(vma->anon_vma, pmd); 1534 } else { 1535 page = follow_trans_huge_pmd(vma, address, 1536 pmd, flags); 1537 spin_unlock(&mm->page_table_lock); 1538 *page_mask = HPAGE_PMD_NR - 1; 1539 goto out; 1540 } 1541 } else 1542 spin_unlock(&mm->page_table_lock); 1543 /* fall through */ 1544 } 1545 split_fallthrough: 1546 if (unlikely(pmd_bad(*pmd))) 1547 goto no_page_table; 1548 1549 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 1550 1551 pte = *ptep; 1552 if (!pte_present(pte)) { 1553 swp_entry_t entry; 1554 /* 1555 * KSM's break_ksm() relies upon recognizing a ksm page 1556 * even while it is being migrated, so for that case we 1557 * need migration_entry_wait(). 1558 */ 1559 if (likely(!(flags & FOLL_MIGRATION))) 1560 goto no_page; 1561 if (pte_none(pte) || pte_file(pte)) 1562 goto no_page; 1563 entry = pte_to_swp_entry(pte); 1564 if (!is_migration_entry(entry)) 1565 goto no_page; 1566 pte_unmap_unlock(ptep, ptl); 1567 migration_entry_wait(mm, pmd, address); 1568 goto split_fallthrough; 1569 } 1570 if ((flags & FOLL_NUMA) && pte_numa(pte)) 1571 goto no_page; 1572 if ((flags & FOLL_WRITE) && !pte_write(pte)) 1573 goto unlock; 1574 1575 page = vm_normal_page(vma, address, pte); 1576 if (unlikely(!page)) { 1577 if ((flags & FOLL_DUMP) || 1578 !is_zero_pfn(pte_pfn(pte))) 1579 goto bad_page; 1580 page = pte_page(pte); 1581 } 1582 1583 if (flags & FOLL_GET) 1584 get_page_foll(page); 1585 if (flags & FOLL_TOUCH) { 1586 if ((flags & FOLL_WRITE) && 1587 !pte_dirty(pte) && !PageDirty(page)) 1588 set_page_dirty(page); 1589 /* 1590 * pte_mkyoung() would be more correct here, but atomic care 1591 * is needed to avoid losing the dirty bit: it is easier to use 1592 * mark_page_accessed(). 1593 */ 1594 mark_page_accessed(page); 1595 } 1596 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) { 1597 /* 1598 * The preliminary mapping check is mainly to avoid the 1599 * pointless overhead of lock_page on the ZERO_PAGE 1600 * which might bounce very badly if there is contention. 1601 * 1602 * If the page is already locked, we don't need to 1603 * handle it now - vmscan will handle it later if and 1604 * when it attempts to reclaim the page. 1605 */ 1606 if (page->mapping && trylock_page(page)) { 1607 lru_add_drain(); /* push cached pages to LRU */ 1608 /* 1609 * Because we lock page here, and migration is 1610 * blocked by the pte's page reference, and we 1611 * know the page is still mapped, we don't even 1612 * need to check for file-cache page truncation. 1613 */ 1614 mlock_vma_page(page); 1615 unlock_page(page); 1616 } 1617 } 1618 unlock: 1619 pte_unmap_unlock(ptep, ptl); 1620 out: 1621 return page; 1622 1623 bad_page: 1624 pte_unmap_unlock(ptep, ptl); 1625 return ERR_PTR(-EFAULT); 1626 1627 no_page: 1628 pte_unmap_unlock(ptep, ptl); 1629 if (!pte_none(pte)) 1630 return page; 1631 1632 no_page_table: 1633 /* 1634 * When core dumping an enormous anonymous area that nobody 1635 * has touched so far, we don't want to allocate unnecessary pages or 1636 * page tables. Return error instead of NULL to skip handle_mm_fault, 1637 * then get_dump_page() will return NULL to leave a hole in the dump. 1638 * But we can only make this optimization where a hole would surely 1639 * be zero-filled if handle_mm_fault() actually did handle it. 1640 */ 1641 if ((flags & FOLL_DUMP) && 1642 (!vma->vm_ops || !vma->vm_ops->fault)) 1643 return ERR_PTR(-EFAULT); 1644 return page; 1645 } 1646 1647 static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) 1648 { 1649 return stack_guard_page_start(vma, addr) || 1650 stack_guard_page_end(vma, addr+PAGE_SIZE); 1651 } 1652 1653 /** 1654 * __get_user_pages() - pin user pages in memory 1655 * @tsk: task_struct of target task 1656 * @mm: mm_struct of target mm 1657 * @start: starting user address 1658 * @nr_pages: number of pages from start to pin 1659 * @gup_flags: flags modifying pin behaviour 1660 * @pages: array that receives pointers to the pages pinned. 1661 * Should be at least nr_pages long. Or NULL, if caller 1662 * only intends to ensure the pages are faulted in. 1663 * @vmas: array of pointers to vmas corresponding to each page. 1664 * Or NULL if the caller does not require them. 1665 * @nonblocking: whether waiting for disk IO or mmap_sem contention 1666 * 1667 * Returns number of pages pinned. This may be fewer than the number 1668 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1669 * were pinned, returns -errno. Each page returned must be released 1670 * with a put_page() call when it is finished with. vmas will only 1671 * remain valid while mmap_sem is held. 1672 * 1673 * Must be called with mmap_sem held for read or write. 1674 * 1675 * __get_user_pages walks a process's page tables and takes a reference to 1676 * each struct page that each user address corresponds to at a given 1677 * instant. That is, it takes the page that would be accessed if a user 1678 * thread accesses the given user virtual address at that instant. 1679 * 1680 * This does not guarantee that the page exists in the user mappings when 1681 * __get_user_pages returns, and there may even be a completely different 1682 * page there in some cases (eg. if mmapped pagecache has been invalidated 1683 * and subsequently re faulted). However it does guarantee that the page 1684 * won't be freed completely. And mostly callers simply care that the page 1685 * contains data that was valid *at some point in time*. Typically, an IO 1686 * or similar operation cannot guarantee anything stronger anyway because 1687 * locks can't be held over the syscall boundary. 1688 * 1689 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If 1690 * the page is written to, set_page_dirty (or set_page_dirty_lock, as 1691 * appropriate) must be called after the page is finished with, and 1692 * before put_page is called. 1693 * 1694 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO 1695 * or mmap_sem contention, and if waiting is needed to pin all pages, 1696 * *@nonblocking will be set to 0. 1697 * 1698 * In most cases, get_user_pages or get_user_pages_fast should be used 1699 * instead of __get_user_pages. __get_user_pages should be used only if 1700 * you need some special @gup_flags. 1701 */ 1702 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1703 unsigned long start, unsigned long nr_pages, 1704 unsigned int gup_flags, struct page **pages, 1705 struct vm_area_struct **vmas, int *nonblocking) 1706 { 1707 long i; 1708 unsigned long vm_flags; 1709 unsigned int page_mask; 1710 1711 if (!nr_pages) 1712 return 0; 1713 1714 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); 1715 1716 /* 1717 * Require read or write permissions. 1718 * If FOLL_FORCE is set, we only require the "MAY" flags. 1719 */ 1720 vm_flags = (gup_flags & FOLL_WRITE) ? 1721 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 1722 vm_flags &= (gup_flags & FOLL_FORCE) ? 1723 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 1724 1725 /* 1726 * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault 1727 * would be called on PROT_NONE ranges. We must never invoke 1728 * handle_mm_fault on PROT_NONE ranges or the NUMA hinting 1729 * page faults would unprotect the PROT_NONE ranges if 1730 * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd 1731 * bitflag. So to avoid that, don't set FOLL_NUMA if 1732 * FOLL_FORCE is set. 1733 */ 1734 if (!(gup_flags & FOLL_FORCE)) 1735 gup_flags |= FOLL_NUMA; 1736 1737 i = 0; 1738 1739 do { 1740 struct vm_area_struct *vma; 1741 1742 vma = find_extend_vma(mm, start); 1743 if (!vma && in_gate_area(mm, start)) { 1744 unsigned long pg = start & PAGE_MASK; 1745 pgd_t *pgd; 1746 pud_t *pud; 1747 pmd_t *pmd; 1748 pte_t *pte; 1749 1750 /* user gate pages are read-only */ 1751 if (gup_flags & FOLL_WRITE) 1752 return i ? : -EFAULT; 1753 if (pg > TASK_SIZE) 1754 pgd = pgd_offset_k(pg); 1755 else 1756 pgd = pgd_offset_gate(mm, pg); 1757 BUG_ON(pgd_none(*pgd)); 1758 pud = pud_offset(pgd, pg); 1759 BUG_ON(pud_none(*pud)); 1760 pmd = pmd_offset(pud, pg); 1761 if (pmd_none(*pmd)) 1762 return i ? : -EFAULT; 1763 VM_BUG_ON(pmd_trans_huge(*pmd)); 1764 pte = pte_offset_map(pmd, pg); 1765 if (pte_none(*pte)) { 1766 pte_unmap(pte); 1767 return i ? : -EFAULT; 1768 } 1769 vma = get_gate_vma(mm); 1770 if (pages) { 1771 struct page *page; 1772 1773 page = vm_normal_page(vma, start, *pte); 1774 if (!page) { 1775 if (!(gup_flags & FOLL_DUMP) && 1776 is_zero_pfn(pte_pfn(*pte))) 1777 page = pte_page(*pte); 1778 else { 1779 pte_unmap(pte); 1780 return i ? : -EFAULT; 1781 } 1782 } 1783 pages[i] = page; 1784 get_page(page); 1785 } 1786 pte_unmap(pte); 1787 page_mask = 0; 1788 goto next_page; 1789 } 1790 1791 if (!vma || 1792 (vma->vm_flags & (VM_IO | VM_PFNMAP)) || 1793 !(vm_flags & vma->vm_flags)) 1794 return i ? : -EFAULT; 1795 1796 if (is_vm_hugetlb_page(vma)) { 1797 i = follow_hugetlb_page(mm, vma, pages, vmas, 1798 &start, &nr_pages, i, gup_flags); 1799 continue; 1800 } 1801 1802 do { 1803 struct page *page; 1804 unsigned int foll_flags = gup_flags; 1805 unsigned int page_increm; 1806 1807 /* 1808 * If we have a pending SIGKILL, don't keep faulting 1809 * pages and potentially allocating memory. 1810 */ 1811 if (unlikely(fatal_signal_pending(current))) 1812 return i ? i : -ERESTARTSYS; 1813 1814 cond_resched(); 1815 while (!(page = follow_page_mask(vma, start, 1816 foll_flags, &page_mask))) { 1817 int ret; 1818 unsigned int fault_flags = 0; 1819 1820 /* For mlock, just skip the stack guard page. */ 1821 if (foll_flags & FOLL_MLOCK) { 1822 if (stack_guard_page(vma, start)) 1823 goto next_page; 1824 } 1825 if (foll_flags & FOLL_WRITE) 1826 fault_flags |= FAULT_FLAG_WRITE; 1827 if (nonblocking) 1828 fault_flags |= FAULT_FLAG_ALLOW_RETRY; 1829 if (foll_flags & FOLL_NOWAIT) 1830 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT); 1831 1832 ret = handle_mm_fault(mm, vma, start, 1833 fault_flags); 1834 1835 if (ret & VM_FAULT_ERROR) { 1836 if (ret & VM_FAULT_OOM) 1837 return i ? i : -ENOMEM; 1838 if (ret & (VM_FAULT_HWPOISON | 1839 VM_FAULT_HWPOISON_LARGE)) { 1840 if (i) 1841 return i; 1842 else if (gup_flags & FOLL_HWPOISON) 1843 return -EHWPOISON; 1844 else 1845 return -EFAULT; 1846 } 1847 if (ret & VM_FAULT_SIGBUS) 1848 return i ? i : -EFAULT; 1849 BUG(); 1850 } 1851 1852 if (tsk) { 1853 if (ret & VM_FAULT_MAJOR) 1854 tsk->maj_flt++; 1855 else 1856 tsk->min_flt++; 1857 } 1858 1859 if (ret & VM_FAULT_RETRY) { 1860 if (nonblocking) 1861 *nonblocking = 0; 1862 return i; 1863 } 1864 1865 /* 1866 * The VM_FAULT_WRITE bit tells us that 1867 * do_wp_page has broken COW when necessary, 1868 * even if maybe_mkwrite decided not to set 1869 * pte_write. We can thus safely do subsequent 1870 * page lookups as if they were reads. But only 1871 * do so when looping for pte_write is futile: 1872 * in some cases userspace may also be wanting 1873 * to write to the gotten user page, which a 1874 * read fault here might prevent (a readonly 1875 * page might get reCOWed by userspace write). 1876 */ 1877 if ((ret & VM_FAULT_WRITE) && 1878 !(vma->vm_flags & VM_WRITE)) 1879 foll_flags &= ~FOLL_WRITE; 1880 1881 cond_resched(); 1882 } 1883 if (IS_ERR(page)) 1884 return i ? i : PTR_ERR(page); 1885 if (pages) { 1886 pages[i] = page; 1887 1888 flush_anon_page(vma, page, start); 1889 flush_dcache_page(page); 1890 page_mask = 0; 1891 } 1892 next_page: 1893 if (vmas) { 1894 vmas[i] = vma; 1895 page_mask = 0; 1896 } 1897 page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask); 1898 if (page_increm > nr_pages) 1899 page_increm = nr_pages; 1900 i += page_increm; 1901 start += page_increm * PAGE_SIZE; 1902 nr_pages -= page_increm; 1903 } while (nr_pages && start < vma->vm_end); 1904 } while (nr_pages); 1905 return i; 1906 } 1907 EXPORT_SYMBOL(__get_user_pages); 1908 1909 /* 1910 * fixup_user_fault() - manually resolve a user page fault 1911 * @tsk: the task_struct to use for page fault accounting, or 1912 * NULL if faults are not to be recorded. 1913 * @mm: mm_struct of target mm 1914 * @address: user address 1915 * @fault_flags:flags to pass down to handle_mm_fault() 1916 * 1917 * This is meant to be called in the specific scenario where for locking reasons 1918 * we try to access user memory in atomic context (within a pagefault_disable() 1919 * section), this returns -EFAULT, and we want to resolve the user fault before 1920 * trying again. 1921 * 1922 * Typically this is meant to be used by the futex code. 1923 * 1924 * The main difference with get_user_pages() is that this function will 1925 * unconditionally call handle_mm_fault() which will in turn perform all the 1926 * necessary SW fixup of the dirty and young bits in the PTE, while 1927 * handle_mm_fault() only guarantees to update these in the struct page. 1928 * 1929 * This is important for some architectures where those bits also gate the 1930 * access permission to the page because they are maintained in software. On 1931 * such architectures, gup() will not be enough to make a subsequent access 1932 * succeed. 1933 * 1934 * This should be called with the mm_sem held for read. 1935 */ 1936 int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, 1937 unsigned long address, unsigned int fault_flags) 1938 { 1939 struct vm_area_struct *vma; 1940 int ret; 1941 1942 vma = find_extend_vma(mm, address); 1943 if (!vma || address < vma->vm_start) 1944 return -EFAULT; 1945 1946 ret = handle_mm_fault(mm, vma, address, fault_flags); 1947 if (ret & VM_FAULT_ERROR) { 1948 if (ret & VM_FAULT_OOM) 1949 return -ENOMEM; 1950 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) 1951 return -EHWPOISON; 1952 if (ret & VM_FAULT_SIGBUS) 1953 return -EFAULT; 1954 BUG(); 1955 } 1956 if (tsk) { 1957 if (ret & VM_FAULT_MAJOR) 1958 tsk->maj_flt++; 1959 else 1960 tsk->min_flt++; 1961 } 1962 return 0; 1963 } 1964 1965 /* 1966 * get_user_pages() - pin user pages in memory 1967 * @tsk: the task_struct to use for page fault accounting, or 1968 * NULL if faults are not to be recorded. 1969 * @mm: mm_struct of target mm 1970 * @start: starting user address 1971 * @nr_pages: number of pages from start to pin 1972 * @write: whether pages will be written to by the caller 1973 * @force: whether to force write access even if user mapping is 1974 * readonly. This will result in the page being COWed even 1975 * in MAP_SHARED mappings. You do not want this. 1976 * @pages: array that receives pointers to the pages pinned. 1977 * Should be at least nr_pages long. Or NULL, if caller 1978 * only intends to ensure the pages are faulted in. 1979 * @vmas: array of pointers to vmas corresponding to each page. 1980 * Or NULL if the caller does not require them. 1981 * 1982 * Returns number of pages pinned. This may be fewer than the number 1983 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1984 * were pinned, returns -errno. Each page returned must be released 1985 * with a put_page() call when it is finished with. vmas will only 1986 * remain valid while mmap_sem is held. 1987 * 1988 * Must be called with mmap_sem held for read or write. 1989 * 1990 * get_user_pages walks a process's page tables and takes a reference to 1991 * each struct page that each user address corresponds to at a given 1992 * instant. That is, it takes the page that would be accessed if a user 1993 * thread accesses the given user virtual address at that instant. 1994 * 1995 * This does not guarantee that the page exists in the user mappings when 1996 * get_user_pages returns, and there may even be a completely different 1997 * page there in some cases (eg. if mmapped pagecache has been invalidated 1998 * and subsequently re faulted). However it does guarantee that the page 1999 * won't be freed completely. And mostly callers simply care that the page 2000 * contains data that was valid *at some point in time*. Typically, an IO 2001 * or similar operation cannot guarantee anything stronger anyway because 2002 * locks can't be held over the syscall boundary. 2003 * 2004 * If write=0, the page must not be written to. If the page is written to, 2005 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called 2006 * after the page is finished with, and before put_page is called. 2007 * 2008 * get_user_pages is typically used for fewer-copy IO operations, to get a 2009 * handle on the memory by some means other than accesses via the user virtual 2010 * addresses. The pages may be submitted for DMA to devices or accessed via 2011 * their kernel linear mapping (via the kmap APIs). Care should be taken to 2012 * use the correct cache flushing APIs. 2013 * 2014 * See also get_user_pages_fast, for performance critical applications. 2015 */ 2016 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 2017 unsigned long start, unsigned long nr_pages, int write, 2018 int force, struct page **pages, struct vm_area_struct **vmas) 2019 { 2020 int flags = FOLL_TOUCH; 2021 2022 if (pages) 2023 flags |= FOLL_GET; 2024 if (write) 2025 flags |= FOLL_WRITE; 2026 if (force) 2027 flags |= FOLL_FORCE; 2028 2029 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 2030 NULL); 2031 } 2032 EXPORT_SYMBOL(get_user_pages); 2033 2034 /** 2035 * get_dump_page() - pin user page in memory while writing it to core dump 2036 * @addr: user address 2037 * 2038 * Returns struct page pointer of user page pinned for dump, 2039 * to be freed afterwards by page_cache_release() or put_page(). 2040 * 2041 * Returns NULL on any kind of failure - a hole must then be inserted into 2042 * the corefile, to preserve alignment with its headers; and also returns 2043 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - 2044 * allowing a hole to be left in the corefile to save diskspace. 2045 * 2046 * Called without mmap_sem, but after all other threads have been killed. 2047 */ 2048 #ifdef CONFIG_ELF_CORE 2049 struct page *get_dump_page(unsigned long addr) 2050 { 2051 struct vm_area_struct *vma; 2052 struct page *page; 2053 2054 if (__get_user_pages(current, current->mm, addr, 1, 2055 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma, 2056 NULL) < 1) 2057 return NULL; 2058 flush_cache_page(vma, addr, page_to_pfn(page)); 2059 return page; 2060 } 2061 #endif /* CONFIG_ELF_CORE */ 2062 2063 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 2064 spinlock_t **ptl) 2065 { 2066 pgd_t * pgd = pgd_offset(mm, addr); 2067 pud_t * pud = pud_alloc(mm, pgd, addr); 2068 if (pud) { 2069 pmd_t * pmd = pmd_alloc(mm, pud, addr); 2070 if (pmd) { 2071 VM_BUG_ON(pmd_trans_huge(*pmd)); 2072 return pte_alloc_map_lock(mm, pmd, addr, ptl); 2073 } 2074 } 2075 return NULL; 2076 } 2077 2078 /* 2079 * This is the old fallback for page remapping. 2080 * 2081 * For historical reasons, it only allows reserved pages. Only 2082 * old drivers should use this, and they needed to mark their 2083 * pages reserved for the old functions anyway. 2084 */ 2085 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 2086 struct page *page, pgprot_t prot) 2087 { 2088 struct mm_struct *mm = vma->vm_mm; 2089 int retval; 2090 pte_t *pte; 2091 spinlock_t *ptl; 2092 2093 retval = -EINVAL; 2094 if (PageAnon(page)) 2095 goto out; 2096 retval = -ENOMEM; 2097 flush_dcache_page(page); 2098 pte = get_locked_pte(mm, addr, &ptl); 2099 if (!pte) 2100 goto out; 2101 retval = -EBUSY; 2102 if (!pte_none(*pte)) 2103 goto out_unlock; 2104 2105 /* Ok, finally just insert the thing.. */ 2106 get_page(page); 2107 inc_mm_counter_fast(mm, MM_FILEPAGES); 2108 page_add_file_rmap(page); 2109 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 2110 2111 retval = 0; 2112 pte_unmap_unlock(pte, ptl); 2113 return retval; 2114 out_unlock: 2115 pte_unmap_unlock(pte, ptl); 2116 out: 2117 return retval; 2118 } 2119 2120 /** 2121 * vm_insert_page - insert single page into user vma 2122 * @vma: user vma to map to 2123 * @addr: target user address of this page 2124 * @page: source kernel page 2125 * 2126 * This allows drivers to insert individual pages they've allocated 2127 * into a user vma. 2128 * 2129 * The page has to be a nice clean _individual_ kernel allocation. 2130 * If you allocate a compound page, you need to have marked it as 2131 * such (__GFP_COMP), or manually just split the page up yourself 2132 * (see split_page()). 2133 * 2134 * NOTE! Traditionally this was done with "remap_pfn_range()" which 2135 * took an arbitrary page protection parameter. This doesn't allow 2136 * that. Your vma protection will have to be set up correctly, which 2137 * means that if you want a shared writable mapping, you'd better 2138 * ask for a shared writable mapping! 2139 * 2140 * The page does not need to be reserved. 2141 * 2142 * Usually this function is called from f_op->mmap() handler 2143 * under mm->mmap_sem write-lock, so it can change vma->vm_flags. 2144 * Caller must set VM_MIXEDMAP on vma if it wants to call this 2145 * function from other places, for example from page-fault handler. 2146 */ 2147 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 2148 struct page *page) 2149 { 2150 if (addr < vma->vm_start || addr >= vma->vm_end) 2151 return -EFAULT; 2152 if (!page_count(page)) 2153 return -EINVAL; 2154 if (!(vma->vm_flags & VM_MIXEDMAP)) { 2155 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); 2156 BUG_ON(vma->vm_flags & VM_PFNMAP); 2157 vma->vm_flags |= VM_MIXEDMAP; 2158 } 2159 return insert_page(vma, addr, page, vma->vm_page_prot); 2160 } 2161 EXPORT_SYMBOL(vm_insert_page); 2162 2163 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2164 unsigned long pfn, pgprot_t prot) 2165 { 2166 struct mm_struct *mm = vma->vm_mm; 2167 int retval; 2168 pte_t *pte, entry; 2169 spinlock_t *ptl; 2170 2171 retval = -ENOMEM; 2172 pte = get_locked_pte(mm, addr, &ptl); 2173 if (!pte) 2174 goto out; 2175 retval = -EBUSY; 2176 if (!pte_none(*pte)) 2177 goto out_unlock; 2178 2179 /* Ok, finally just insert the thing.. */ 2180 entry = pte_mkspecial(pfn_pte(pfn, prot)); 2181 set_pte_at(mm, addr, pte, entry); 2182 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 2183 2184 retval = 0; 2185 out_unlock: 2186 pte_unmap_unlock(pte, ptl); 2187 out: 2188 return retval; 2189 } 2190 2191 /** 2192 * vm_insert_pfn - insert single pfn into user vma 2193 * @vma: user vma to map to 2194 * @addr: target user address of this page 2195 * @pfn: source kernel pfn 2196 * 2197 * Similar to vm_insert_page, this allows drivers to insert individual pages 2198 * they've allocated into a user vma. Same comments apply. 2199 * 2200 * This function should only be called from a vm_ops->fault handler, and 2201 * in that case the handler should return NULL. 2202 * 2203 * vma cannot be a COW mapping. 2204 * 2205 * As this is called only for pages that do not currently exist, we 2206 * do not need to flush old virtual caches or the TLB. 2207 */ 2208 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 2209 unsigned long pfn) 2210 { 2211 int ret; 2212 pgprot_t pgprot = vma->vm_page_prot; 2213 /* 2214 * Technically, architectures with pte_special can avoid all these 2215 * restrictions (same for remap_pfn_range). However we would like 2216 * consistency in testing and feature parity among all, so we should 2217 * try to keep these invariants in place for everybody. 2218 */ 2219 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 2220 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 2221 (VM_PFNMAP|VM_MIXEDMAP)); 2222 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 2223 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 2224 2225 if (addr < vma->vm_start || addr >= vma->vm_end) 2226 return -EFAULT; 2227 if (track_pfn_insert(vma, &pgprot, pfn)) 2228 return -EINVAL; 2229 2230 ret = insert_pfn(vma, addr, pfn, pgprot); 2231 2232 return ret; 2233 } 2234 EXPORT_SYMBOL(vm_insert_pfn); 2235 2236 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 2237 unsigned long pfn) 2238 { 2239 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 2240 2241 if (addr < vma->vm_start || addr >= vma->vm_end) 2242 return -EFAULT; 2243 2244 /* 2245 * If we don't have pte special, then we have to use the pfn_valid() 2246 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 2247 * refcount the page if pfn_valid is true (hence insert_page rather 2248 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 2249 * without pte special, it would there be refcounted as a normal page. 2250 */ 2251 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 2252 struct page *page; 2253 2254 page = pfn_to_page(pfn); 2255 return insert_page(vma, addr, page, vma->vm_page_prot); 2256 } 2257 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 2258 } 2259 EXPORT_SYMBOL(vm_insert_mixed); 2260 2261 /* 2262 * maps a range of physical memory into the requested pages. the old 2263 * mappings are removed. any references to nonexistent pages results 2264 * in null mappings (currently treated as "copy-on-access") 2265 */ 2266 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 2267 unsigned long addr, unsigned long end, 2268 unsigned long pfn, pgprot_t prot) 2269 { 2270 pte_t *pte; 2271 spinlock_t *ptl; 2272 2273 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 2274 if (!pte) 2275 return -ENOMEM; 2276 arch_enter_lazy_mmu_mode(); 2277 do { 2278 BUG_ON(!pte_none(*pte)); 2279 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 2280 pfn++; 2281 } while (pte++, addr += PAGE_SIZE, addr != end); 2282 arch_leave_lazy_mmu_mode(); 2283 pte_unmap_unlock(pte - 1, ptl); 2284 return 0; 2285 } 2286 2287 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 2288 unsigned long addr, unsigned long end, 2289 unsigned long pfn, pgprot_t prot) 2290 { 2291 pmd_t *pmd; 2292 unsigned long next; 2293 2294 pfn -= addr >> PAGE_SHIFT; 2295 pmd = pmd_alloc(mm, pud, addr); 2296 if (!pmd) 2297 return -ENOMEM; 2298 VM_BUG_ON(pmd_trans_huge(*pmd)); 2299 do { 2300 next = pmd_addr_end(addr, end); 2301 if (remap_pte_range(mm, pmd, addr, next, 2302 pfn + (addr >> PAGE_SHIFT), prot)) 2303 return -ENOMEM; 2304 } while (pmd++, addr = next, addr != end); 2305 return 0; 2306 } 2307 2308 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 2309 unsigned long addr, unsigned long end, 2310 unsigned long pfn, pgprot_t prot) 2311 { 2312 pud_t *pud; 2313 unsigned long next; 2314 2315 pfn -= addr >> PAGE_SHIFT; 2316 pud = pud_alloc(mm, pgd, addr); 2317 if (!pud) 2318 return -ENOMEM; 2319 do { 2320 next = pud_addr_end(addr, end); 2321 if (remap_pmd_range(mm, pud, addr, next, 2322 pfn + (addr >> PAGE_SHIFT), prot)) 2323 return -ENOMEM; 2324 } while (pud++, addr = next, addr != end); 2325 return 0; 2326 } 2327 2328 /** 2329 * remap_pfn_range - remap kernel memory to userspace 2330 * @vma: user vma to map to 2331 * @addr: target user address to start at 2332 * @pfn: physical address of kernel memory 2333 * @size: size of map area 2334 * @prot: page protection flags for this mapping 2335 * 2336 * Note: this is only safe if the mm semaphore is held when called. 2337 */ 2338 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 2339 unsigned long pfn, unsigned long size, pgprot_t prot) 2340 { 2341 pgd_t *pgd; 2342 unsigned long next; 2343 unsigned long end = addr + PAGE_ALIGN(size); 2344 struct mm_struct *mm = vma->vm_mm; 2345 int err; 2346 2347 /* 2348 * Physically remapped pages are special. Tell the 2349 * rest of the world about it: 2350 * VM_IO tells people not to look at these pages 2351 * (accesses can have side effects). 2352 * VM_PFNMAP tells the core MM that the base pages are just 2353 * raw PFN mappings, and do not have a "struct page" associated 2354 * with them. 2355 * VM_DONTEXPAND 2356 * Disable vma merging and expanding with mremap(). 2357 * VM_DONTDUMP 2358 * Omit vma from core dump, even when VM_IO turned off. 2359 * 2360 * There's a horrible special case to handle copy-on-write 2361 * behaviour that some programs depend on. We mark the "original" 2362 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 2363 * See vm_normal_page() for details. 2364 */ 2365 if (is_cow_mapping(vma->vm_flags)) { 2366 if (addr != vma->vm_start || end != vma->vm_end) 2367 return -EINVAL; 2368 vma->vm_pgoff = pfn; 2369 } 2370 2371 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); 2372 if (err) 2373 return -EINVAL; 2374 2375 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 2376 2377 BUG_ON(addr >= end); 2378 pfn -= addr >> PAGE_SHIFT; 2379 pgd = pgd_offset(mm, addr); 2380 flush_cache_range(vma, addr, end); 2381 do { 2382 next = pgd_addr_end(addr, end); 2383 err = remap_pud_range(mm, pgd, addr, next, 2384 pfn + (addr >> PAGE_SHIFT), prot); 2385 if (err) 2386 break; 2387 } while (pgd++, addr = next, addr != end); 2388 2389 if (err) 2390 untrack_pfn(vma, pfn, PAGE_ALIGN(size)); 2391 2392 return err; 2393 } 2394 EXPORT_SYMBOL(remap_pfn_range); 2395 2396 /** 2397 * vm_iomap_memory - remap memory to userspace 2398 * @vma: user vma to map to 2399 * @start: start of area 2400 * @len: size of area 2401 * 2402 * This is a simplified io_remap_pfn_range() for common driver use. The 2403 * driver just needs to give us the physical memory range to be mapped, 2404 * we'll figure out the rest from the vma information. 2405 * 2406 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get 2407 * whatever write-combining details or similar. 2408 */ 2409 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 2410 { 2411 unsigned long vm_len, pfn, pages; 2412 2413 /* Check that the physical memory area passed in looks valid */ 2414 if (start + len < start) 2415 return -EINVAL; 2416 /* 2417 * You *really* shouldn't map things that aren't page-aligned, 2418 * but we've historically allowed it because IO memory might 2419 * just have smaller alignment. 2420 */ 2421 len += start & ~PAGE_MASK; 2422 pfn = start >> PAGE_SHIFT; 2423 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; 2424 if (pfn + pages < pfn) 2425 return -EINVAL; 2426 2427 /* We start the mapping 'vm_pgoff' pages into the area */ 2428 if (vma->vm_pgoff > pages) 2429 return -EINVAL; 2430 pfn += vma->vm_pgoff; 2431 pages -= vma->vm_pgoff; 2432 2433 /* Can we fit all of the mapping? */ 2434 vm_len = vma->vm_end - vma->vm_start; 2435 if (vm_len >> PAGE_SHIFT > pages) 2436 return -EINVAL; 2437 2438 /* Ok, let it rip */ 2439 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 2440 } 2441 EXPORT_SYMBOL(vm_iomap_memory); 2442 2443 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 2444 unsigned long addr, unsigned long end, 2445 pte_fn_t fn, void *data) 2446 { 2447 pte_t *pte; 2448 int err; 2449 pgtable_t token; 2450 spinlock_t *uninitialized_var(ptl); 2451 2452 pte = (mm == &init_mm) ? 2453 pte_alloc_kernel(pmd, addr) : 2454 pte_alloc_map_lock(mm, pmd, addr, &ptl); 2455 if (!pte) 2456 return -ENOMEM; 2457 2458 BUG_ON(pmd_huge(*pmd)); 2459 2460 arch_enter_lazy_mmu_mode(); 2461 2462 token = pmd_pgtable(*pmd); 2463 2464 do { 2465 err = fn(pte++, token, addr, data); 2466 if (err) 2467 break; 2468 } while (addr += PAGE_SIZE, addr != end); 2469 2470 arch_leave_lazy_mmu_mode(); 2471 2472 if (mm != &init_mm) 2473 pte_unmap_unlock(pte-1, ptl); 2474 return err; 2475 } 2476 2477 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 2478 unsigned long addr, unsigned long end, 2479 pte_fn_t fn, void *data) 2480 { 2481 pmd_t *pmd; 2482 unsigned long next; 2483 int err; 2484 2485 BUG_ON(pud_huge(*pud)); 2486 2487 pmd = pmd_alloc(mm, pud, addr); 2488 if (!pmd) 2489 return -ENOMEM; 2490 do { 2491 next = pmd_addr_end(addr, end); 2492 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 2493 if (err) 2494 break; 2495 } while (pmd++, addr = next, addr != end); 2496 return err; 2497 } 2498 2499 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 2500 unsigned long addr, unsigned long end, 2501 pte_fn_t fn, void *data) 2502 { 2503 pud_t *pud; 2504 unsigned long next; 2505 int err; 2506 2507 pud = pud_alloc(mm, pgd, addr); 2508 if (!pud) 2509 return -ENOMEM; 2510 do { 2511 next = pud_addr_end(addr, end); 2512 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 2513 if (err) 2514 break; 2515 } while (pud++, addr = next, addr != end); 2516 return err; 2517 } 2518 2519 /* 2520 * Scan a region of virtual memory, filling in page tables as necessary 2521 * and calling a provided function on each leaf page table. 2522 */ 2523 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2524 unsigned long size, pte_fn_t fn, void *data) 2525 { 2526 pgd_t *pgd; 2527 unsigned long next; 2528 unsigned long end = addr + size; 2529 int err; 2530 2531 BUG_ON(addr >= end); 2532 pgd = pgd_offset(mm, addr); 2533 do { 2534 next = pgd_addr_end(addr, end); 2535 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 2536 if (err) 2537 break; 2538 } while (pgd++, addr = next, addr != end); 2539 2540 return err; 2541 } 2542 EXPORT_SYMBOL_GPL(apply_to_page_range); 2543 2544 /* 2545 * handle_pte_fault chooses page fault handler according to an entry 2546 * which was read non-atomically. Before making any commitment, on 2547 * those architectures or configurations (e.g. i386 with PAE) which 2548 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault 2549 * must check under lock before unmapping the pte and proceeding 2550 * (but do_wp_page is only called after already making such a check; 2551 * and do_anonymous_page can safely check later on). 2552 */ 2553 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 2554 pte_t *page_table, pte_t orig_pte) 2555 { 2556 int same = 1; 2557 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 2558 if (sizeof(pte_t) > sizeof(unsigned long)) { 2559 spinlock_t *ptl = pte_lockptr(mm, pmd); 2560 spin_lock(ptl); 2561 same = pte_same(*page_table, orig_pte); 2562 spin_unlock(ptl); 2563 } 2564 #endif 2565 pte_unmap(page_table); 2566 return same; 2567 } 2568 2569 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 2570 { 2571 /* 2572 * If the source page was a PFN mapping, we don't have 2573 * a "struct page" for it. We do a best-effort copy by 2574 * just copying from the original user address. If that 2575 * fails, we just zero-fill it. Live with it. 2576 */ 2577 if (unlikely(!src)) { 2578 void *kaddr = kmap_atomic(dst); 2579 void __user *uaddr = (void __user *)(va & PAGE_MASK); 2580 2581 /* 2582 * This really shouldn't fail, because the page is there 2583 * in the page tables. But it might just be unreadable, 2584 * in which case we just give up and fill the result with 2585 * zeroes. 2586 */ 2587 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 2588 clear_page(kaddr); 2589 kunmap_atomic(kaddr); 2590 flush_dcache_page(dst); 2591 } else 2592 copy_user_highpage(dst, src, va, vma); 2593 } 2594 2595 /* 2596 * This routine handles present pages, when users try to write 2597 * to a shared page. It is done by copying the page to a new address 2598 * and decrementing the shared-page counter for the old page. 2599 * 2600 * Note that this routine assumes that the protection checks have been 2601 * done by the caller (the low-level page fault routine in most cases). 2602 * Thus we can safely just mark it writable once we've done any necessary 2603 * COW. 2604 * 2605 * We also mark the page dirty at this point even though the page will 2606 * change only once the write actually happens. This avoids a few races, 2607 * and potentially makes it more efficient. 2608 * 2609 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2610 * but allow concurrent faults), with pte both mapped and locked. 2611 * We return with mmap_sem still held, but pte unmapped and unlocked. 2612 */ 2613 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 2614 unsigned long address, pte_t *page_table, pmd_t *pmd, 2615 spinlock_t *ptl, pte_t orig_pte) 2616 __releases(ptl) 2617 { 2618 struct page *old_page, *new_page = NULL; 2619 pte_t entry; 2620 int ret = 0; 2621 int page_mkwrite = 0; 2622 struct page *dirty_page = NULL; 2623 unsigned long mmun_start = 0; /* For mmu_notifiers */ 2624 unsigned long mmun_end = 0; /* For mmu_notifiers */ 2625 2626 old_page = vm_normal_page(vma, address, orig_pte); 2627 if (!old_page) { 2628 /* 2629 * VM_MIXEDMAP !pfn_valid() case 2630 * 2631 * We should not cow pages in a shared writeable mapping. 2632 * Just mark the pages writable as we can't do any dirty 2633 * accounting on raw pfn maps. 2634 */ 2635 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2636 (VM_WRITE|VM_SHARED)) 2637 goto reuse; 2638 goto gotten; 2639 } 2640 2641 /* 2642 * Take out anonymous pages first, anonymous shared vmas are 2643 * not dirty accountable. 2644 */ 2645 if (PageAnon(old_page) && !PageKsm(old_page)) { 2646 if (!trylock_page(old_page)) { 2647 page_cache_get(old_page); 2648 pte_unmap_unlock(page_table, ptl); 2649 lock_page(old_page); 2650 page_table = pte_offset_map_lock(mm, pmd, address, 2651 &ptl); 2652 if (!pte_same(*page_table, orig_pte)) { 2653 unlock_page(old_page); 2654 goto unlock; 2655 } 2656 page_cache_release(old_page); 2657 } 2658 if (reuse_swap_page(old_page)) { 2659 /* 2660 * The page is all ours. Move it to our anon_vma so 2661 * the rmap code will not search our parent or siblings. 2662 * Protected against the rmap code by the page lock. 2663 */ 2664 page_move_anon_rmap(old_page, vma, address); 2665 unlock_page(old_page); 2666 goto reuse; 2667 } 2668 unlock_page(old_page); 2669 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2670 (VM_WRITE|VM_SHARED))) { 2671 /* 2672 * Only catch write-faults on shared writable pages, 2673 * read-only shared pages can get COWed by 2674 * get_user_pages(.write=1, .force=1). 2675 */ 2676 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2677 struct vm_fault vmf; 2678 int tmp; 2679 2680 vmf.virtual_address = (void __user *)(address & 2681 PAGE_MASK); 2682 vmf.pgoff = old_page->index; 2683 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2684 vmf.page = old_page; 2685 2686 /* 2687 * Notify the address space that the page is about to 2688 * become writable so that it can prohibit this or wait 2689 * for the page to get into an appropriate state. 2690 * 2691 * We do this without the lock held, so that it can 2692 * sleep if it needs to. 2693 */ 2694 page_cache_get(old_page); 2695 pte_unmap_unlock(page_table, ptl); 2696 2697 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 2698 if (unlikely(tmp & 2699 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2700 ret = tmp; 2701 goto unwritable_page; 2702 } 2703 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 2704 lock_page(old_page); 2705 if (!old_page->mapping) { 2706 ret = 0; /* retry the fault */ 2707 unlock_page(old_page); 2708 goto unwritable_page; 2709 } 2710 } else 2711 VM_BUG_ON(!PageLocked(old_page)); 2712 2713 /* 2714 * Since we dropped the lock we need to revalidate 2715 * the PTE as someone else may have changed it. If 2716 * they did, we just return, as we can count on the 2717 * MMU to tell us if they didn't also make it writable. 2718 */ 2719 page_table = pte_offset_map_lock(mm, pmd, address, 2720 &ptl); 2721 if (!pte_same(*page_table, orig_pte)) { 2722 unlock_page(old_page); 2723 goto unlock; 2724 } 2725 2726 page_mkwrite = 1; 2727 } 2728 dirty_page = old_page; 2729 get_page(dirty_page); 2730 2731 reuse: 2732 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2733 entry = pte_mkyoung(orig_pte); 2734 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2735 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2736 update_mmu_cache(vma, address, page_table); 2737 pte_unmap_unlock(page_table, ptl); 2738 ret |= VM_FAULT_WRITE; 2739 2740 if (!dirty_page) 2741 return ret; 2742 2743 /* 2744 * Yes, Virginia, this is actually required to prevent a race 2745 * with clear_page_dirty_for_io() from clearing the page dirty 2746 * bit after it clear all dirty ptes, but before a racing 2747 * do_wp_page installs a dirty pte. 2748 * 2749 * __do_fault is protected similarly. 2750 */ 2751 if (!page_mkwrite) { 2752 wait_on_page_locked(dirty_page); 2753 set_page_dirty_balance(dirty_page, page_mkwrite); 2754 /* file_update_time outside page_lock */ 2755 if (vma->vm_file) 2756 file_update_time(vma->vm_file); 2757 } 2758 put_page(dirty_page); 2759 if (page_mkwrite) { 2760 struct address_space *mapping = dirty_page->mapping; 2761 2762 set_page_dirty(dirty_page); 2763 unlock_page(dirty_page); 2764 page_cache_release(dirty_page); 2765 if (mapping) { 2766 /* 2767 * Some device drivers do not set page.mapping 2768 * but still dirty their pages 2769 */ 2770 balance_dirty_pages_ratelimited(mapping); 2771 } 2772 } 2773 2774 return ret; 2775 } 2776 2777 /* 2778 * Ok, we need to copy. Oh, well.. 2779 */ 2780 page_cache_get(old_page); 2781 gotten: 2782 pte_unmap_unlock(page_table, ptl); 2783 2784 if (unlikely(anon_vma_prepare(vma))) 2785 goto oom; 2786 2787 if (is_zero_pfn(pte_pfn(orig_pte))) { 2788 new_page = alloc_zeroed_user_highpage_movable(vma, address); 2789 if (!new_page) 2790 goto oom; 2791 } else { 2792 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2793 if (!new_page) 2794 goto oom; 2795 cow_user_page(new_page, old_page, address, vma); 2796 } 2797 __SetPageUptodate(new_page); 2798 2799 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) 2800 goto oom_free_new; 2801 2802 mmun_start = address & PAGE_MASK; 2803 mmun_end = mmun_start + PAGE_SIZE; 2804 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2805 2806 /* 2807 * Re-check the pte - we dropped the lock 2808 */ 2809 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2810 if (likely(pte_same(*page_table, orig_pte))) { 2811 if (old_page) { 2812 if (!PageAnon(old_page)) { 2813 dec_mm_counter_fast(mm, MM_FILEPAGES); 2814 inc_mm_counter_fast(mm, MM_ANONPAGES); 2815 } 2816 } else 2817 inc_mm_counter_fast(mm, MM_ANONPAGES); 2818 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2819 entry = mk_pte(new_page, vma->vm_page_prot); 2820 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2821 /* 2822 * Clear the pte entry and flush it first, before updating the 2823 * pte with the new entry. This will avoid a race condition 2824 * seen in the presence of one thread doing SMC and another 2825 * thread doing COW. 2826 */ 2827 ptep_clear_flush(vma, address, page_table); 2828 page_add_new_anon_rmap(new_page, vma, address); 2829 /* 2830 * We call the notify macro here because, when using secondary 2831 * mmu page tables (such as kvm shadow page tables), we want the 2832 * new page to be mapped directly into the secondary page table. 2833 */ 2834 set_pte_at_notify(mm, address, page_table, entry); 2835 update_mmu_cache(vma, address, page_table); 2836 if (old_page) { 2837 /* 2838 * Only after switching the pte to the new page may 2839 * we remove the mapcount here. Otherwise another 2840 * process may come and find the rmap count decremented 2841 * before the pte is switched to the new page, and 2842 * "reuse" the old page writing into it while our pte 2843 * here still points into it and can be read by other 2844 * threads. 2845 * 2846 * The critical issue is to order this 2847 * page_remove_rmap with the ptp_clear_flush above. 2848 * Those stores are ordered by (if nothing else,) 2849 * the barrier present in the atomic_add_negative 2850 * in page_remove_rmap. 2851 * 2852 * Then the TLB flush in ptep_clear_flush ensures that 2853 * no process can access the old page before the 2854 * decremented mapcount is visible. And the old page 2855 * cannot be reused until after the decremented 2856 * mapcount is visible. So transitively, TLBs to 2857 * old page will be flushed before it can be reused. 2858 */ 2859 page_remove_rmap(old_page); 2860 } 2861 2862 /* Free the old page.. */ 2863 new_page = old_page; 2864 ret |= VM_FAULT_WRITE; 2865 } else 2866 mem_cgroup_uncharge_page(new_page); 2867 2868 if (new_page) 2869 page_cache_release(new_page); 2870 unlock: 2871 pte_unmap_unlock(page_table, ptl); 2872 if (mmun_end > mmun_start) 2873 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2874 if (old_page) { 2875 /* 2876 * Don't let another task, with possibly unlocked vma, 2877 * keep the mlocked page. 2878 */ 2879 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { 2880 lock_page(old_page); /* LRU manipulation */ 2881 munlock_vma_page(old_page); 2882 unlock_page(old_page); 2883 } 2884 page_cache_release(old_page); 2885 } 2886 return ret; 2887 oom_free_new: 2888 page_cache_release(new_page); 2889 oom: 2890 if (old_page) 2891 page_cache_release(old_page); 2892 return VM_FAULT_OOM; 2893 2894 unwritable_page: 2895 page_cache_release(old_page); 2896 return ret; 2897 } 2898 2899 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 2900 unsigned long start_addr, unsigned long end_addr, 2901 struct zap_details *details) 2902 { 2903 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 2904 } 2905 2906 static inline void unmap_mapping_range_tree(struct rb_root *root, 2907 struct zap_details *details) 2908 { 2909 struct vm_area_struct *vma; 2910 pgoff_t vba, vea, zba, zea; 2911 2912 vma_interval_tree_foreach(vma, root, 2913 details->first_index, details->last_index) { 2914 2915 vba = vma->vm_pgoff; 2916 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 2917 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2918 zba = details->first_index; 2919 if (zba < vba) 2920 zba = vba; 2921 zea = details->last_index; 2922 if (zea > vea) 2923 zea = vea; 2924 2925 unmap_mapping_range_vma(vma, 2926 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2927 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2928 details); 2929 } 2930 } 2931 2932 static inline void unmap_mapping_range_list(struct list_head *head, 2933 struct zap_details *details) 2934 { 2935 struct vm_area_struct *vma; 2936 2937 /* 2938 * In nonlinear VMAs there is no correspondence between virtual address 2939 * offset and file offset. So we must perform an exhaustive search 2940 * across *all* the pages in each nonlinear VMA, not just the pages 2941 * whose virtual address lies outside the file truncation point. 2942 */ 2943 list_for_each_entry(vma, head, shared.nonlinear) { 2944 details->nonlinear_vma = vma; 2945 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details); 2946 } 2947 } 2948 2949 /** 2950 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2951 * @mapping: the address space containing mmaps to be unmapped. 2952 * @holebegin: byte in first page to unmap, relative to the start of 2953 * the underlying file. This will be rounded down to a PAGE_SIZE 2954 * boundary. Note that this is different from truncate_pagecache(), which 2955 * must keep the partial page. In contrast, we must get rid of 2956 * partial pages. 2957 * @holelen: size of prospective hole in bytes. This will be rounded 2958 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2959 * end of the file. 2960 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2961 * but 0 when invalidating pagecache, don't throw away private data. 2962 */ 2963 void unmap_mapping_range(struct address_space *mapping, 2964 loff_t const holebegin, loff_t const holelen, int even_cows) 2965 { 2966 struct zap_details details; 2967 pgoff_t hba = holebegin >> PAGE_SHIFT; 2968 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2969 2970 /* Check for overflow. */ 2971 if (sizeof(holelen) > sizeof(hlen)) { 2972 long long holeend = 2973 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2974 if (holeend & ~(long long)ULONG_MAX) 2975 hlen = ULONG_MAX - hba + 1; 2976 } 2977 2978 details.check_mapping = even_cows? NULL: mapping; 2979 details.nonlinear_vma = NULL; 2980 details.first_index = hba; 2981 details.last_index = hba + hlen - 1; 2982 if (details.last_index < details.first_index) 2983 details.last_index = ULONG_MAX; 2984 2985 2986 mutex_lock(&mapping->i_mmap_mutex); 2987 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) 2988 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2989 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 2990 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 2991 mutex_unlock(&mapping->i_mmap_mutex); 2992 } 2993 EXPORT_SYMBOL(unmap_mapping_range); 2994 2995 /* 2996 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2997 * but allow concurrent faults), and pte mapped but not yet locked. 2998 * We return with mmap_sem still held, but pte unmapped and unlocked. 2999 */ 3000 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 3001 unsigned long address, pte_t *page_table, pmd_t *pmd, 3002 unsigned int flags, pte_t orig_pte) 3003 { 3004 spinlock_t *ptl; 3005 struct page *page, *swapcache; 3006 swp_entry_t entry; 3007 pte_t pte; 3008 int locked; 3009 struct mem_cgroup *ptr; 3010 int exclusive = 0; 3011 int ret = 0; 3012 3013 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3014 goto out; 3015 3016 entry = pte_to_swp_entry(orig_pte); 3017 if (unlikely(non_swap_entry(entry))) { 3018 if (is_migration_entry(entry)) { 3019 migration_entry_wait(mm, pmd, address); 3020 } else if (is_hwpoison_entry(entry)) { 3021 ret = VM_FAULT_HWPOISON; 3022 } else { 3023 print_bad_pte(vma, address, orig_pte, NULL); 3024 ret = VM_FAULT_SIGBUS; 3025 } 3026 goto out; 3027 } 3028 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 3029 page = lookup_swap_cache(entry); 3030 if (!page) { 3031 page = swapin_readahead(entry, 3032 GFP_HIGHUSER_MOVABLE, vma, address); 3033 if (!page) { 3034 /* 3035 * Back out if somebody else faulted in this pte 3036 * while we released the pte lock. 3037 */ 3038 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3039 if (likely(pte_same(*page_table, orig_pte))) 3040 ret = VM_FAULT_OOM; 3041 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 3042 goto unlock; 3043 } 3044 3045 /* Had to read the page from swap area: Major fault */ 3046 ret = VM_FAULT_MAJOR; 3047 count_vm_event(PGMAJFAULT); 3048 mem_cgroup_count_vm_event(mm, PGMAJFAULT); 3049 } else if (PageHWPoison(page)) { 3050 /* 3051 * hwpoisoned dirty swapcache pages are kept for killing 3052 * owner processes (which may be unknown at hwpoison time) 3053 */ 3054 ret = VM_FAULT_HWPOISON; 3055 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 3056 swapcache = page; 3057 goto out_release; 3058 } 3059 3060 swapcache = page; 3061 locked = lock_page_or_retry(page, mm, flags); 3062 3063 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 3064 if (!locked) { 3065 ret |= VM_FAULT_RETRY; 3066 goto out_release; 3067 } 3068 3069 /* 3070 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 3071 * release the swapcache from under us. The page pin, and pte_same 3072 * test below, are not enough to exclude that. Even if it is still 3073 * swapcache, we need to check that the page's swap has not changed. 3074 */ 3075 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) 3076 goto out_page; 3077 3078 page = ksm_might_need_to_copy(page, vma, address); 3079 if (unlikely(!page)) { 3080 ret = VM_FAULT_OOM; 3081 page = swapcache; 3082 goto out_page; 3083 } 3084 3085 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { 3086 ret = VM_FAULT_OOM; 3087 goto out_page; 3088 } 3089 3090 /* 3091 * Back out if somebody else already faulted in this pte. 3092 */ 3093 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3094 if (unlikely(!pte_same(*page_table, orig_pte))) 3095 goto out_nomap; 3096 3097 if (unlikely(!PageUptodate(page))) { 3098 ret = VM_FAULT_SIGBUS; 3099 goto out_nomap; 3100 } 3101 3102 /* 3103 * The page isn't present yet, go ahead with the fault. 3104 * 3105 * Be careful about the sequence of operations here. 3106 * To get its accounting right, reuse_swap_page() must be called 3107 * while the page is counted on swap but not yet in mapcount i.e. 3108 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 3109 * must be called after the swap_free(), or it will never succeed. 3110 * Because delete_from_swap_page() may be called by reuse_swap_page(), 3111 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry 3112 * in page->private. In this case, a record in swap_cgroup is silently 3113 * discarded at swap_free(). 3114 */ 3115 3116 inc_mm_counter_fast(mm, MM_ANONPAGES); 3117 dec_mm_counter_fast(mm, MM_SWAPENTS); 3118 pte = mk_pte(page, vma->vm_page_prot); 3119 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 3120 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 3121 flags &= ~FAULT_FLAG_WRITE; 3122 ret |= VM_FAULT_WRITE; 3123 exclusive = 1; 3124 } 3125 flush_icache_page(vma, page); 3126 set_pte_at(mm, address, page_table, pte); 3127 if (page == swapcache) 3128 do_page_add_anon_rmap(page, vma, address, exclusive); 3129 else /* ksm created a completely new copy */ 3130 page_add_new_anon_rmap(page, vma, address); 3131 /* It's better to call commit-charge after rmap is established */ 3132 mem_cgroup_commit_charge_swapin(page, ptr); 3133 3134 swap_free(entry); 3135 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 3136 try_to_free_swap(page); 3137 unlock_page(page); 3138 if (page != swapcache) { 3139 /* 3140 * Hold the lock to avoid the swap entry to be reused 3141 * until we take the PT lock for the pte_same() check 3142 * (to avoid false positives from pte_same). For 3143 * further safety release the lock after the swap_free 3144 * so that the swap count won't change under a 3145 * parallel locked swapcache. 3146 */ 3147 unlock_page(swapcache); 3148 page_cache_release(swapcache); 3149 } 3150 3151 if (flags & FAULT_FLAG_WRITE) { 3152 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 3153 if (ret & VM_FAULT_ERROR) 3154 ret &= VM_FAULT_ERROR; 3155 goto out; 3156 } 3157 3158 /* No need to invalidate - it was non-present before */ 3159 update_mmu_cache(vma, address, page_table); 3160 unlock: 3161 pte_unmap_unlock(page_table, ptl); 3162 out: 3163 return ret; 3164 out_nomap: 3165 mem_cgroup_cancel_charge_swapin(ptr); 3166 pte_unmap_unlock(page_table, ptl); 3167 out_page: 3168 unlock_page(page); 3169 out_release: 3170 page_cache_release(page); 3171 if (page != swapcache) { 3172 unlock_page(swapcache); 3173 page_cache_release(swapcache); 3174 } 3175 return ret; 3176 } 3177 3178 /* 3179 * This is like a special single-page "expand_{down|up}wards()", 3180 * except we must first make sure that 'address{-|+}PAGE_SIZE' 3181 * doesn't hit another vma. 3182 */ 3183 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) 3184 { 3185 address &= PAGE_MASK; 3186 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { 3187 struct vm_area_struct *prev = vma->vm_prev; 3188 3189 /* 3190 * Is there a mapping abutting this one below? 3191 * 3192 * That's only ok if it's the same stack mapping 3193 * that has gotten split.. 3194 */ 3195 if (prev && prev->vm_end == address) 3196 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; 3197 3198 expand_downwards(vma, address - PAGE_SIZE); 3199 } 3200 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { 3201 struct vm_area_struct *next = vma->vm_next; 3202 3203 /* As VM_GROWSDOWN but s/below/above/ */ 3204 if (next && next->vm_start == address + PAGE_SIZE) 3205 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; 3206 3207 expand_upwards(vma, address + PAGE_SIZE); 3208 } 3209 return 0; 3210 } 3211 3212 /* 3213 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3214 * but allow concurrent faults), and pte mapped but not yet locked. 3215 * We return with mmap_sem still held, but pte unmapped and unlocked. 3216 */ 3217 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 3218 unsigned long address, pte_t *page_table, pmd_t *pmd, 3219 unsigned int flags) 3220 { 3221 struct page *page; 3222 spinlock_t *ptl; 3223 pte_t entry; 3224 3225 pte_unmap(page_table); 3226 3227 /* Check if we need to add a guard page to the stack */ 3228 if (check_stack_guard_page(vma, address) < 0) 3229 return VM_FAULT_SIGBUS; 3230 3231 /* Use the zero-page for reads */ 3232 if (!(flags & FAULT_FLAG_WRITE)) { 3233 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), 3234 vma->vm_page_prot)); 3235 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3236 if (!pte_none(*page_table)) 3237 goto unlock; 3238 goto setpte; 3239 } 3240 3241 /* Allocate our own private page. */ 3242 if (unlikely(anon_vma_prepare(vma))) 3243 goto oom; 3244 page = alloc_zeroed_user_highpage_movable(vma, address); 3245 if (!page) 3246 goto oom; 3247 /* 3248 * The memory barrier inside __SetPageUptodate makes sure that 3249 * preceeding stores to the page contents become visible before 3250 * the set_pte_at() write. 3251 */ 3252 __SetPageUptodate(page); 3253 3254 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) 3255 goto oom_free_page; 3256 3257 entry = mk_pte(page, vma->vm_page_prot); 3258 if (vma->vm_flags & VM_WRITE) 3259 entry = pte_mkwrite(pte_mkdirty(entry)); 3260 3261 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3262 if (!pte_none(*page_table)) 3263 goto release; 3264 3265 inc_mm_counter_fast(mm, MM_ANONPAGES); 3266 page_add_new_anon_rmap(page, vma, address); 3267 setpte: 3268 set_pte_at(mm, address, page_table, entry); 3269 3270 /* No need to invalidate - it was non-present before */ 3271 update_mmu_cache(vma, address, page_table); 3272 unlock: 3273 pte_unmap_unlock(page_table, ptl); 3274 return 0; 3275 release: 3276 mem_cgroup_uncharge_page(page); 3277 page_cache_release(page); 3278 goto unlock; 3279 oom_free_page: 3280 page_cache_release(page); 3281 oom: 3282 return VM_FAULT_OOM; 3283 } 3284 3285 /* 3286 * __do_fault() tries to create a new page mapping. It aggressively 3287 * tries to share with existing pages, but makes a separate copy if 3288 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 3289 * the next page fault. 3290 * 3291 * As this is called only for pages that do not currently exist, we 3292 * do not need to flush old virtual caches or the TLB. 3293 * 3294 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3295 * but allow concurrent faults), and pte neither mapped nor locked. 3296 * We return with mmap_sem still held, but pte unmapped and unlocked. 3297 */ 3298 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3299 unsigned long address, pmd_t *pmd, 3300 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 3301 { 3302 pte_t *page_table; 3303 spinlock_t *ptl; 3304 struct page *page; 3305 struct page *cow_page; 3306 pte_t entry; 3307 int anon = 0; 3308 struct page *dirty_page = NULL; 3309 struct vm_fault vmf; 3310 int ret; 3311 int page_mkwrite = 0; 3312 3313 /* 3314 * If we do COW later, allocate page befor taking lock_page() 3315 * on the file cache page. This will reduce lock holding time. 3316 */ 3317 if ((flags & FAULT_FLAG_WRITE) && !(vma->vm_flags & VM_SHARED)) { 3318 3319 if (unlikely(anon_vma_prepare(vma))) 3320 return VM_FAULT_OOM; 3321 3322 cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 3323 if (!cow_page) 3324 return VM_FAULT_OOM; 3325 3326 if (mem_cgroup_newpage_charge(cow_page, mm, GFP_KERNEL)) { 3327 page_cache_release(cow_page); 3328 return VM_FAULT_OOM; 3329 } 3330 } else 3331 cow_page = NULL; 3332 3333 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 3334 vmf.pgoff = pgoff; 3335 vmf.flags = flags; 3336 vmf.page = NULL; 3337 3338 ret = vma->vm_ops->fault(vma, &vmf); 3339 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | 3340 VM_FAULT_RETRY))) 3341 goto uncharge_out; 3342 3343 if (unlikely(PageHWPoison(vmf.page))) { 3344 if (ret & VM_FAULT_LOCKED) 3345 unlock_page(vmf.page); 3346 ret = VM_FAULT_HWPOISON; 3347 goto uncharge_out; 3348 } 3349 3350 /* 3351 * For consistency in subsequent calls, make the faulted page always 3352 * locked. 3353 */ 3354 if (unlikely(!(ret & VM_FAULT_LOCKED))) 3355 lock_page(vmf.page); 3356 else 3357 VM_BUG_ON(!PageLocked(vmf.page)); 3358 3359 /* 3360 * Should we do an early C-O-W break? 3361 */ 3362 page = vmf.page; 3363 if (flags & FAULT_FLAG_WRITE) { 3364 if (!(vma->vm_flags & VM_SHARED)) { 3365 page = cow_page; 3366 anon = 1; 3367 copy_user_highpage(page, vmf.page, address, vma); 3368 __SetPageUptodate(page); 3369 } else { 3370 /* 3371 * If the page will be shareable, see if the backing 3372 * address space wants to know that the page is about 3373 * to become writable 3374 */ 3375 if (vma->vm_ops->page_mkwrite) { 3376 int tmp; 3377 3378 unlock_page(page); 3379 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 3380 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 3381 if (unlikely(tmp & 3382 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 3383 ret = tmp; 3384 goto unwritable_page; 3385 } 3386 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 3387 lock_page(page); 3388 if (!page->mapping) { 3389 ret = 0; /* retry the fault */ 3390 unlock_page(page); 3391 goto unwritable_page; 3392 } 3393 } else 3394 VM_BUG_ON(!PageLocked(page)); 3395 page_mkwrite = 1; 3396 } 3397 } 3398 3399 } 3400 3401 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3402 3403 /* 3404 * This silly early PAGE_DIRTY setting removes a race 3405 * due to the bad i386 page protection. But it's valid 3406 * for other architectures too. 3407 * 3408 * Note that if FAULT_FLAG_WRITE is set, we either now have 3409 * an exclusive copy of the page, or this is a shared mapping, 3410 * so we can make it writable and dirty to avoid having to 3411 * handle that later. 3412 */ 3413 /* Only go through if we didn't race with anybody else... */ 3414 if (likely(pte_same(*page_table, orig_pte))) { 3415 flush_icache_page(vma, page); 3416 entry = mk_pte(page, vma->vm_page_prot); 3417 if (flags & FAULT_FLAG_WRITE) 3418 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3419 if (anon) { 3420 inc_mm_counter_fast(mm, MM_ANONPAGES); 3421 page_add_new_anon_rmap(page, vma, address); 3422 } else { 3423 inc_mm_counter_fast(mm, MM_FILEPAGES); 3424 page_add_file_rmap(page); 3425 if (flags & FAULT_FLAG_WRITE) { 3426 dirty_page = page; 3427 get_page(dirty_page); 3428 } 3429 } 3430 set_pte_at(mm, address, page_table, entry); 3431 3432 /* no need to invalidate: a not-present page won't be cached */ 3433 update_mmu_cache(vma, address, page_table); 3434 } else { 3435 if (cow_page) 3436 mem_cgroup_uncharge_page(cow_page); 3437 if (anon) 3438 page_cache_release(page); 3439 else 3440 anon = 1; /* no anon but release faulted_page */ 3441 } 3442 3443 pte_unmap_unlock(page_table, ptl); 3444 3445 if (dirty_page) { 3446 struct address_space *mapping = page->mapping; 3447 int dirtied = 0; 3448 3449 if (set_page_dirty(dirty_page)) 3450 dirtied = 1; 3451 unlock_page(dirty_page); 3452 put_page(dirty_page); 3453 if ((dirtied || page_mkwrite) && mapping) { 3454 /* 3455 * Some device drivers do not set page.mapping but still 3456 * dirty their pages 3457 */ 3458 balance_dirty_pages_ratelimited(mapping); 3459 } 3460 3461 /* file_update_time outside page_lock */ 3462 if (vma->vm_file && !page_mkwrite) 3463 file_update_time(vma->vm_file); 3464 } else { 3465 unlock_page(vmf.page); 3466 if (anon) 3467 page_cache_release(vmf.page); 3468 } 3469 3470 return ret; 3471 3472 unwritable_page: 3473 page_cache_release(page); 3474 return ret; 3475 uncharge_out: 3476 /* fs's fault handler get error */ 3477 if (cow_page) { 3478 mem_cgroup_uncharge_page(cow_page); 3479 page_cache_release(cow_page); 3480 } 3481 return ret; 3482 } 3483 3484 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3485 unsigned long address, pte_t *page_table, pmd_t *pmd, 3486 unsigned int flags, pte_t orig_pte) 3487 { 3488 pgoff_t pgoff = (((address & PAGE_MASK) 3489 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 3490 3491 pte_unmap(page_table); 3492 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3493 } 3494 3495 /* 3496 * Fault of a previously existing named mapping. Repopulate the pte 3497 * from the encoded file_pte if possible. This enables swappable 3498 * nonlinear vmas. 3499 * 3500 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3501 * but allow concurrent faults), and pte mapped but not yet locked. 3502 * We return with mmap_sem still held, but pte unmapped and unlocked. 3503 */ 3504 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3505 unsigned long address, pte_t *page_table, pmd_t *pmd, 3506 unsigned int flags, pte_t orig_pte) 3507 { 3508 pgoff_t pgoff; 3509 3510 flags |= FAULT_FLAG_NONLINEAR; 3511 3512 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3513 return 0; 3514 3515 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 3516 /* 3517 * Page table corrupted: show pte and kill process. 3518 */ 3519 print_bad_pte(vma, address, orig_pte, NULL); 3520 return VM_FAULT_SIGBUS; 3521 } 3522 3523 pgoff = pte_to_pgoff(orig_pte); 3524 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3525 } 3526 3527 int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, 3528 unsigned long addr, int current_nid) 3529 { 3530 get_page(page); 3531 3532 count_vm_numa_event(NUMA_HINT_FAULTS); 3533 if (current_nid == numa_node_id()) 3534 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 3535 3536 return mpol_misplaced(page, vma, addr); 3537 } 3538 3539 int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 3540 unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd) 3541 { 3542 struct page *page = NULL; 3543 spinlock_t *ptl; 3544 int current_nid = -1; 3545 int target_nid; 3546 bool migrated = false; 3547 3548 /* 3549 * The "pte" at this point cannot be used safely without 3550 * validation through pte_unmap_same(). It's of NUMA type but 3551 * the pfn may be screwed if the read is non atomic. 3552 * 3553 * ptep_modify_prot_start is not called as this is clearing 3554 * the _PAGE_NUMA bit and it is not really expected that there 3555 * would be concurrent hardware modifications to the PTE. 3556 */ 3557 ptl = pte_lockptr(mm, pmd); 3558 spin_lock(ptl); 3559 if (unlikely(!pte_same(*ptep, pte))) { 3560 pte_unmap_unlock(ptep, ptl); 3561 goto out; 3562 } 3563 3564 pte = pte_mknonnuma(pte); 3565 set_pte_at(mm, addr, ptep, pte); 3566 update_mmu_cache(vma, addr, ptep); 3567 3568 page = vm_normal_page(vma, addr, pte); 3569 if (!page) { 3570 pte_unmap_unlock(ptep, ptl); 3571 return 0; 3572 } 3573 3574 current_nid = page_to_nid(page); 3575 target_nid = numa_migrate_prep(page, vma, addr, current_nid); 3576 pte_unmap_unlock(ptep, ptl); 3577 if (target_nid == -1) { 3578 /* 3579 * Account for the fault against the current node if it not 3580 * being replaced regardless of where the page is located. 3581 */ 3582 current_nid = numa_node_id(); 3583 put_page(page); 3584 goto out; 3585 } 3586 3587 /* Migrate to the requested node */ 3588 migrated = migrate_misplaced_page(page, target_nid); 3589 if (migrated) 3590 current_nid = target_nid; 3591 3592 out: 3593 if (current_nid != -1) 3594 task_numa_fault(current_nid, 1, migrated); 3595 return 0; 3596 } 3597 3598 /* NUMA hinting page fault entry point for regular pmds */ 3599 #ifdef CONFIG_NUMA_BALANCING 3600 static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 3601 unsigned long addr, pmd_t *pmdp) 3602 { 3603 pmd_t pmd; 3604 pte_t *pte, *orig_pte; 3605 unsigned long _addr = addr & PMD_MASK; 3606 unsigned long offset; 3607 spinlock_t *ptl; 3608 bool numa = false; 3609 int local_nid = numa_node_id(); 3610 3611 spin_lock(&mm->page_table_lock); 3612 pmd = *pmdp; 3613 if (pmd_numa(pmd)) { 3614 set_pmd_at(mm, _addr, pmdp, pmd_mknonnuma(pmd)); 3615 numa = true; 3616 } 3617 spin_unlock(&mm->page_table_lock); 3618 3619 if (!numa) 3620 return 0; 3621 3622 /* we're in a page fault so some vma must be in the range */ 3623 BUG_ON(!vma); 3624 BUG_ON(vma->vm_start >= _addr + PMD_SIZE); 3625 offset = max(_addr, vma->vm_start) & ~PMD_MASK; 3626 VM_BUG_ON(offset >= PMD_SIZE); 3627 orig_pte = pte = pte_offset_map_lock(mm, pmdp, _addr, &ptl); 3628 pte += offset >> PAGE_SHIFT; 3629 for (addr = _addr + offset; addr < _addr + PMD_SIZE; pte++, addr += PAGE_SIZE) { 3630 pte_t pteval = *pte; 3631 struct page *page; 3632 int curr_nid = local_nid; 3633 int target_nid; 3634 bool migrated; 3635 if (!pte_present(pteval)) 3636 continue; 3637 if (!pte_numa(pteval)) 3638 continue; 3639 if (addr >= vma->vm_end) { 3640 vma = find_vma(mm, addr); 3641 /* there's a pte present so there must be a vma */ 3642 BUG_ON(!vma); 3643 BUG_ON(addr < vma->vm_start); 3644 } 3645 if (pte_numa(pteval)) { 3646 pteval = pte_mknonnuma(pteval); 3647 set_pte_at(mm, addr, pte, pteval); 3648 } 3649 page = vm_normal_page(vma, addr, pteval); 3650 if (unlikely(!page)) 3651 continue; 3652 /* only check non-shared pages */ 3653 if (unlikely(page_mapcount(page) != 1)) 3654 continue; 3655 3656 /* 3657 * Note that the NUMA fault is later accounted to either 3658 * the node that is currently running or where the page is 3659 * migrated to. 3660 */ 3661 curr_nid = local_nid; 3662 target_nid = numa_migrate_prep(page, vma, addr, 3663 page_to_nid(page)); 3664 if (target_nid == -1) { 3665 put_page(page); 3666 continue; 3667 } 3668 3669 /* Migrate to the requested node */ 3670 pte_unmap_unlock(pte, ptl); 3671 migrated = migrate_misplaced_page(page, target_nid); 3672 if (migrated) 3673 curr_nid = target_nid; 3674 task_numa_fault(curr_nid, 1, migrated); 3675 3676 pte = pte_offset_map_lock(mm, pmdp, addr, &ptl); 3677 } 3678 pte_unmap_unlock(orig_pte, ptl); 3679 3680 return 0; 3681 } 3682 #else 3683 static int do_pmd_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 3684 unsigned long addr, pmd_t *pmdp) 3685 { 3686 BUG(); 3687 return 0; 3688 } 3689 #endif /* CONFIG_NUMA_BALANCING */ 3690 3691 /* 3692 * These routines also need to handle stuff like marking pages dirty 3693 * and/or accessed for architectures that don't do it in hardware (most 3694 * RISC architectures). The early dirtying is also good on the i386. 3695 * 3696 * There is also a hook called "update_mmu_cache()" that architectures 3697 * with external mmu caches can use to update those (ie the Sparc or 3698 * PowerPC hashed page tables that act as extended TLBs). 3699 * 3700 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3701 * but allow concurrent faults), and pte mapped but not yet locked. 3702 * We return with mmap_sem still held, but pte unmapped and unlocked. 3703 */ 3704 int handle_pte_fault(struct mm_struct *mm, 3705 struct vm_area_struct *vma, unsigned long address, 3706 pte_t *pte, pmd_t *pmd, unsigned int flags) 3707 { 3708 pte_t entry; 3709 spinlock_t *ptl; 3710 3711 entry = *pte; 3712 if (!pte_present(entry)) { 3713 if (pte_none(entry)) { 3714 if (vma->vm_ops) { 3715 if (likely(vma->vm_ops->fault)) 3716 return do_linear_fault(mm, vma, address, 3717 pte, pmd, flags, entry); 3718 } 3719 return do_anonymous_page(mm, vma, address, 3720 pte, pmd, flags); 3721 } 3722 if (pte_file(entry)) 3723 return do_nonlinear_fault(mm, vma, address, 3724 pte, pmd, flags, entry); 3725 return do_swap_page(mm, vma, address, 3726 pte, pmd, flags, entry); 3727 } 3728 3729 if (pte_numa(entry)) 3730 return do_numa_page(mm, vma, address, entry, pte, pmd); 3731 3732 ptl = pte_lockptr(mm, pmd); 3733 spin_lock(ptl); 3734 if (unlikely(!pte_same(*pte, entry))) 3735 goto unlock; 3736 if (flags & FAULT_FLAG_WRITE) { 3737 if (!pte_write(entry)) 3738 return do_wp_page(mm, vma, address, 3739 pte, pmd, ptl, entry); 3740 entry = pte_mkdirty(entry); 3741 } 3742 entry = pte_mkyoung(entry); 3743 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 3744 update_mmu_cache(vma, address, pte); 3745 } else { 3746 /* 3747 * This is needed only for protection faults but the arch code 3748 * is not yet telling us if this is a protection fault or not. 3749 * This still avoids useless tlb flushes for .text page faults 3750 * with threads. 3751 */ 3752 if (flags & FAULT_FLAG_WRITE) 3753 flush_tlb_fix_spurious_fault(vma, address); 3754 } 3755 unlock: 3756 pte_unmap_unlock(pte, ptl); 3757 return 0; 3758 } 3759 3760 /* 3761 * By the time we get here, we already hold the mm semaphore 3762 */ 3763 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3764 unsigned long address, unsigned int flags) 3765 { 3766 pgd_t *pgd; 3767 pud_t *pud; 3768 pmd_t *pmd; 3769 pte_t *pte; 3770 3771 __set_current_state(TASK_RUNNING); 3772 3773 count_vm_event(PGFAULT); 3774 mem_cgroup_count_vm_event(mm, PGFAULT); 3775 3776 /* do counter updates before entering really critical section. */ 3777 check_sync_rss_stat(current); 3778 3779 if (unlikely(is_vm_hugetlb_page(vma))) 3780 return hugetlb_fault(mm, vma, address, flags); 3781 3782 retry: 3783 pgd = pgd_offset(mm, address); 3784 pud = pud_alloc(mm, pgd, address); 3785 if (!pud) 3786 return VM_FAULT_OOM; 3787 pmd = pmd_alloc(mm, pud, address); 3788 if (!pmd) 3789 return VM_FAULT_OOM; 3790 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { 3791 if (!vma->vm_ops) 3792 return do_huge_pmd_anonymous_page(mm, vma, address, 3793 pmd, flags); 3794 } else { 3795 pmd_t orig_pmd = *pmd; 3796 int ret; 3797 3798 barrier(); 3799 if (pmd_trans_huge(orig_pmd)) { 3800 unsigned int dirty = flags & FAULT_FLAG_WRITE; 3801 3802 /* 3803 * If the pmd is splitting, return and retry the 3804 * the fault. Alternative: wait until the split 3805 * is done, and goto retry. 3806 */ 3807 if (pmd_trans_splitting(orig_pmd)) 3808 return 0; 3809 3810 if (pmd_numa(orig_pmd)) 3811 return do_huge_pmd_numa_page(mm, vma, address, 3812 orig_pmd, pmd); 3813 3814 if (dirty && !pmd_write(orig_pmd)) { 3815 ret = do_huge_pmd_wp_page(mm, vma, address, pmd, 3816 orig_pmd); 3817 /* 3818 * If COW results in an oom, the huge pmd will 3819 * have been split, so retry the fault on the 3820 * pte for a smaller charge. 3821 */ 3822 if (unlikely(ret & VM_FAULT_OOM)) 3823 goto retry; 3824 return ret; 3825 } else { 3826 huge_pmd_set_accessed(mm, vma, address, pmd, 3827 orig_pmd, dirty); 3828 } 3829 3830 return 0; 3831 } 3832 } 3833 3834 if (pmd_numa(*pmd)) 3835 return do_pmd_numa_page(mm, vma, address, pmd); 3836 3837 /* 3838 * Use __pte_alloc instead of pte_alloc_map, because we can't 3839 * run pte_offset_map on the pmd, if an huge pmd could 3840 * materialize from under us from a different thread. 3841 */ 3842 if (unlikely(pmd_none(*pmd)) && 3843 unlikely(__pte_alloc(mm, vma, pmd, address))) 3844 return VM_FAULT_OOM; 3845 /* if an huge pmd materialized from under us just retry later */ 3846 if (unlikely(pmd_trans_huge(*pmd))) 3847 return 0; 3848 /* 3849 * A regular pmd is established and it can't morph into a huge pmd 3850 * from under us anymore at this point because we hold the mmap_sem 3851 * read mode and khugepaged takes it in write mode. So now it's 3852 * safe to run pte_offset_map(). 3853 */ 3854 pte = pte_offset_map(pmd, address); 3855 3856 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 3857 } 3858 3859 #ifndef __PAGETABLE_PUD_FOLDED 3860 /* 3861 * Allocate page upper directory. 3862 * We've already handled the fast-path in-line. 3863 */ 3864 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3865 { 3866 pud_t *new = pud_alloc_one(mm, address); 3867 if (!new) 3868 return -ENOMEM; 3869 3870 smp_wmb(); /* See comment in __pte_alloc */ 3871 3872 spin_lock(&mm->page_table_lock); 3873 if (pgd_present(*pgd)) /* Another has populated it */ 3874 pud_free(mm, new); 3875 else 3876 pgd_populate(mm, pgd, new); 3877 spin_unlock(&mm->page_table_lock); 3878 return 0; 3879 } 3880 #endif /* __PAGETABLE_PUD_FOLDED */ 3881 3882 #ifndef __PAGETABLE_PMD_FOLDED 3883 /* 3884 * Allocate page middle directory. 3885 * We've already handled the fast-path in-line. 3886 */ 3887 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 3888 { 3889 pmd_t *new = pmd_alloc_one(mm, address); 3890 if (!new) 3891 return -ENOMEM; 3892 3893 smp_wmb(); /* See comment in __pte_alloc */ 3894 3895 spin_lock(&mm->page_table_lock); 3896 #ifndef __ARCH_HAS_4LEVEL_HACK 3897 if (pud_present(*pud)) /* Another has populated it */ 3898 pmd_free(mm, new); 3899 else 3900 pud_populate(mm, pud, new); 3901 #else 3902 if (pgd_present(*pud)) /* Another has populated it */ 3903 pmd_free(mm, new); 3904 else 3905 pgd_populate(mm, pud, new); 3906 #endif /* __ARCH_HAS_4LEVEL_HACK */ 3907 spin_unlock(&mm->page_table_lock); 3908 return 0; 3909 } 3910 #endif /* __PAGETABLE_PMD_FOLDED */ 3911 3912 #if !defined(__HAVE_ARCH_GATE_AREA) 3913 3914 #if defined(AT_SYSINFO_EHDR) 3915 static struct vm_area_struct gate_vma; 3916 3917 static int __init gate_vma_init(void) 3918 { 3919 gate_vma.vm_mm = NULL; 3920 gate_vma.vm_start = FIXADDR_USER_START; 3921 gate_vma.vm_end = FIXADDR_USER_END; 3922 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 3923 gate_vma.vm_page_prot = __P101; 3924 3925 return 0; 3926 } 3927 __initcall(gate_vma_init); 3928 #endif 3929 3930 struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 3931 { 3932 #ifdef AT_SYSINFO_EHDR 3933 return &gate_vma; 3934 #else 3935 return NULL; 3936 #endif 3937 } 3938 3939 int in_gate_area_no_mm(unsigned long addr) 3940 { 3941 #ifdef AT_SYSINFO_EHDR 3942 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 3943 return 1; 3944 #endif 3945 return 0; 3946 } 3947 3948 #endif /* __HAVE_ARCH_GATE_AREA */ 3949 3950 static int __follow_pte(struct mm_struct *mm, unsigned long address, 3951 pte_t **ptepp, spinlock_t **ptlp) 3952 { 3953 pgd_t *pgd; 3954 pud_t *pud; 3955 pmd_t *pmd; 3956 pte_t *ptep; 3957 3958 pgd = pgd_offset(mm, address); 3959 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 3960 goto out; 3961 3962 pud = pud_offset(pgd, address); 3963 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 3964 goto out; 3965 3966 pmd = pmd_offset(pud, address); 3967 VM_BUG_ON(pmd_trans_huge(*pmd)); 3968 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 3969 goto out; 3970 3971 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 3972 if (pmd_huge(*pmd)) 3973 goto out; 3974 3975 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 3976 if (!ptep) 3977 goto out; 3978 if (!pte_present(*ptep)) 3979 goto unlock; 3980 *ptepp = ptep; 3981 return 0; 3982 unlock: 3983 pte_unmap_unlock(ptep, *ptlp); 3984 out: 3985 return -EINVAL; 3986 } 3987 3988 static inline int follow_pte(struct mm_struct *mm, unsigned long address, 3989 pte_t **ptepp, spinlock_t **ptlp) 3990 { 3991 int res; 3992 3993 /* (void) is needed to make gcc happy */ 3994 (void) __cond_lock(*ptlp, 3995 !(res = __follow_pte(mm, address, ptepp, ptlp))); 3996 return res; 3997 } 3998 3999 /** 4000 * follow_pfn - look up PFN at a user virtual address 4001 * @vma: memory mapping 4002 * @address: user virtual address 4003 * @pfn: location to store found PFN 4004 * 4005 * Only IO mappings and raw PFN mappings are allowed. 4006 * 4007 * Returns zero and the pfn at @pfn on success, -ve otherwise. 4008 */ 4009 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 4010 unsigned long *pfn) 4011 { 4012 int ret = -EINVAL; 4013 spinlock_t *ptl; 4014 pte_t *ptep; 4015 4016 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4017 return ret; 4018 4019 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 4020 if (ret) 4021 return ret; 4022 *pfn = pte_pfn(*ptep); 4023 pte_unmap_unlock(ptep, ptl); 4024 return 0; 4025 } 4026 EXPORT_SYMBOL(follow_pfn); 4027 4028 #ifdef CONFIG_HAVE_IOREMAP_PROT 4029 int follow_phys(struct vm_area_struct *vma, 4030 unsigned long address, unsigned int flags, 4031 unsigned long *prot, resource_size_t *phys) 4032 { 4033 int ret = -EINVAL; 4034 pte_t *ptep, pte; 4035 spinlock_t *ptl; 4036 4037 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 4038 goto out; 4039 4040 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 4041 goto out; 4042 pte = *ptep; 4043 4044 if ((flags & FOLL_WRITE) && !pte_write(pte)) 4045 goto unlock; 4046 4047 *prot = pgprot_val(pte_pgprot(pte)); 4048 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 4049 4050 ret = 0; 4051 unlock: 4052 pte_unmap_unlock(ptep, ptl); 4053 out: 4054 return ret; 4055 } 4056 4057 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 4058 void *buf, int len, int write) 4059 { 4060 resource_size_t phys_addr; 4061 unsigned long prot = 0; 4062 void __iomem *maddr; 4063 int offset = addr & (PAGE_SIZE-1); 4064 4065 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 4066 return -EINVAL; 4067 4068 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 4069 if (write) 4070 memcpy_toio(maddr + offset, buf, len); 4071 else 4072 memcpy_fromio(buf, maddr + offset, len); 4073 iounmap(maddr); 4074 4075 return len; 4076 } 4077 #endif 4078 4079 /* 4080 * Access another process' address space as given in mm. If non-NULL, use the 4081 * given task for page fault accounting. 4082 */ 4083 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 4084 unsigned long addr, void *buf, int len, int write) 4085 { 4086 struct vm_area_struct *vma; 4087 void *old_buf = buf; 4088 4089 down_read(&mm->mmap_sem); 4090 /* ignore errors, just check how much was successfully transferred */ 4091 while (len) { 4092 int bytes, ret, offset; 4093 void *maddr; 4094 struct page *page = NULL; 4095 4096 ret = get_user_pages(tsk, mm, addr, 1, 4097 write, 1, &page, &vma); 4098 if (ret <= 0) { 4099 /* 4100 * Check if this is a VM_IO | VM_PFNMAP VMA, which 4101 * we can access using slightly different code. 4102 */ 4103 #ifdef CONFIG_HAVE_IOREMAP_PROT 4104 vma = find_vma(mm, addr); 4105 if (!vma || vma->vm_start > addr) 4106 break; 4107 if (vma->vm_ops && vma->vm_ops->access) 4108 ret = vma->vm_ops->access(vma, addr, buf, 4109 len, write); 4110 if (ret <= 0) 4111 #endif 4112 break; 4113 bytes = ret; 4114 } else { 4115 bytes = len; 4116 offset = addr & (PAGE_SIZE-1); 4117 if (bytes > PAGE_SIZE-offset) 4118 bytes = PAGE_SIZE-offset; 4119 4120 maddr = kmap(page); 4121 if (write) { 4122 copy_to_user_page(vma, page, addr, 4123 maddr + offset, buf, bytes); 4124 set_page_dirty_lock(page); 4125 } else { 4126 copy_from_user_page(vma, page, addr, 4127 buf, maddr + offset, bytes); 4128 } 4129 kunmap(page); 4130 page_cache_release(page); 4131 } 4132 len -= bytes; 4133 buf += bytes; 4134 addr += bytes; 4135 } 4136 up_read(&mm->mmap_sem); 4137 4138 return buf - old_buf; 4139 } 4140 4141 /** 4142 * access_remote_vm - access another process' address space 4143 * @mm: the mm_struct of the target address space 4144 * @addr: start address to access 4145 * @buf: source or destination buffer 4146 * @len: number of bytes to transfer 4147 * @write: whether the access is a write 4148 * 4149 * The caller must hold a reference on @mm. 4150 */ 4151 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 4152 void *buf, int len, int write) 4153 { 4154 return __access_remote_vm(NULL, mm, addr, buf, len, write); 4155 } 4156 4157 /* 4158 * Access another process' address space. 4159 * Source/target buffer must be kernel space, 4160 * Do not walk the page table directly, use get_user_pages 4161 */ 4162 int access_process_vm(struct task_struct *tsk, unsigned long addr, 4163 void *buf, int len, int write) 4164 { 4165 struct mm_struct *mm; 4166 int ret; 4167 4168 mm = get_task_mm(tsk); 4169 if (!mm) 4170 return 0; 4171 4172 ret = __access_remote_vm(tsk, mm, addr, buf, len, write); 4173 mmput(mm); 4174 4175 return ret; 4176 } 4177 4178 /* 4179 * Print the name of a VMA. 4180 */ 4181 void print_vma_addr(char *prefix, unsigned long ip) 4182 { 4183 struct mm_struct *mm = current->mm; 4184 struct vm_area_struct *vma; 4185 4186 /* 4187 * Do not print if we are in atomic 4188 * contexts (in exception stacks, etc.): 4189 */ 4190 if (preempt_count()) 4191 return; 4192 4193 down_read(&mm->mmap_sem); 4194 vma = find_vma(mm, ip); 4195 if (vma && vma->vm_file) { 4196 struct file *f = vma->vm_file; 4197 char *buf = (char *)__get_free_page(GFP_KERNEL); 4198 if (buf) { 4199 char *p; 4200 4201 p = d_path(&f->f_path, buf, PAGE_SIZE); 4202 if (IS_ERR(p)) 4203 p = "?"; 4204 printk("%s%s[%lx+%lx]", prefix, kbasename(p), 4205 vma->vm_start, 4206 vma->vm_end - vma->vm_start); 4207 free_page((unsigned long)buf); 4208 } 4209 } 4210 up_read(&mm->mmap_sem); 4211 } 4212 4213 #ifdef CONFIG_PROVE_LOCKING 4214 void might_fault(void) 4215 { 4216 /* 4217 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 4218 * holding the mmap_sem, this is safe because kernel memory doesn't 4219 * get paged out, therefore we'll never actually fault, and the 4220 * below annotations will generate false positives. 4221 */ 4222 if (segment_eq(get_fs(), KERNEL_DS)) 4223 return; 4224 4225 might_sleep(); 4226 /* 4227 * it would be nicer only to annotate paths which are not under 4228 * pagefault_disable, however that requires a larger audit and 4229 * providing helpers like get_user_atomic. 4230 */ 4231 if (!in_atomic() && current->mm) 4232 might_lock_read(¤t->mm->mmap_sem); 4233 } 4234 EXPORT_SYMBOL(might_fault); 4235 #endif 4236 4237 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 4238 static void clear_gigantic_page(struct page *page, 4239 unsigned long addr, 4240 unsigned int pages_per_huge_page) 4241 { 4242 int i; 4243 struct page *p = page; 4244 4245 might_sleep(); 4246 for (i = 0; i < pages_per_huge_page; 4247 i++, p = mem_map_next(p, page, i)) { 4248 cond_resched(); 4249 clear_user_highpage(p, addr + i * PAGE_SIZE); 4250 } 4251 } 4252 void clear_huge_page(struct page *page, 4253 unsigned long addr, unsigned int pages_per_huge_page) 4254 { 4255 int i; 4256 4257 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4258 clear_gigantic_page(page, addr, pages_per_huge_page); 4259 return; 4260 } 4261 4262 might_sleep(); 4263 for (i = 0; i < pages_per_huge_page; i++) { 4264 cond_resched(); 4265 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 4266 } 4267 } 4268 4269 static void copy_user_gigantic_page(struct page *dst, struct page *src, 4270 unsigned long addr, 4271 struct vm_area_struct *vma, 4272 unsigned int pages_per_huge_page) 4273 { 4274 int i; 4275 struct page *dst_base = dst; 4276 struct page *src_base = src; 4277 4278 for (i = 0; i < pages_per_huge_page; ) { 4279 cond_resched(); 4280 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 4281 4282 i++; 4283 dst = mem_map_next(dst, dst_base, i); 4284 src = mem_map_next(src, src_base, i); 4285 } 4286 } 4287 4288 void copy_user_huge_page(struct page *dst, struct page *src, 4289 unsigned long addr, struct vm_area_struct *vma, 4290 unsigned int pages_per_huge_page) 4291 { 4292 int i; 4293 4294 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 4295 copy_user_gigantic_page(dst, src, addr, vma, 4296 pages_per_huge_page); 4297 return; 4298 } 4299 4300 might_sleep(); 4301 for (i = 0; i < pages_per_huge_page; i++) { 4302 cond_resched(); 4303 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 4304 } 4305 } 4306 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 4307