1 /* 2 * linux/mm/memory.c 3 * 4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 5 */ 6 7 /* 8 * demand-loading started 01.12.91 - seems it is high on the list of 9 * things wanted, and it should be easy to implement. - Linus 10 */ 11 12 /* 13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared 14 * pages started 02.12.91, seems to work. - Linus. 15 * 16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it 17 * would have taken more than the 6M I have free, but it worked well as 18 * far as I could see. 19 * 20 * Also corrected some "invalidate()"s - I wasn't doing enough of them. 21 */ 22 23 /* 24 * Real VM (paging to/from disk) started 18.12.91. Much more work and 25 * thought has to go into this. Oh, well.. 26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. 27 * Found it. Everything seems to work now. 28 * 20.12.91 - Ok, making the swap-device changeable like the root. 29 */ 30 31 /* 32 * 05.04.94 - Multi-page memory management added for v1.1. 33 * Idea by Alex Bligh (alex@cconcepts.co.uk) 34 * 35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG 36 * (Gerhard.Wichert@pdb.siemens.de) 37 * 38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) 39 */ 40 41 #include <linux/kernel_stat.h> 42 #include <linux/mm.h> 43 #include <linux/hugetlb.h> 44 #include <linux/mman.h> 45 #include <linux/swap.h> 46 #include <linux/highmem.h> 47 #include <linux/pagemap.h> 48 #include <linux/ksm.h> 49 #include <linux/rmap.h> 50 #include <linux/export.h> 51 #include <linux/delayacct.h> 52 #include <linux/init.h> 53 #include <linux/writeback.h> 54 #include <linux/memcontrol.h> 55 #include <linux/mmu_notifier.h> 56 #include <linux/kallsyms.h> 57 #include <linux/swapops.h> 58 #include <linux/elf.h> 59 #include <linux/gfp.h> 60 #include <linux/migrate.h> 61 #include <linux/string.h> 62 #include <linux/dma-debug.h> 63 #include <linux/debugfs.h> 64 65 #include <asm/io.h> 66 #include <asm/pgalloc.h> 67 #include <asm/uaccess.h> 68 #include <asm/tlb.h> 69 #include <asm/tlbflush.h> 70 #include <asm/pgtable.h> 71 72 #include "internal.h" 73 74 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS 75 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid. 76 #endif 77 78 #ifndef CONFIG_NEED_MULTIPLE_NODES 79 /* use the per-pgdat data instead for discontigmem - mbligh */ 80 unsigned long max_mapnr; 81 struct page *mem_map; 82 83 EXPORT_SYMBOL(max_mapnr); 84 EXPORT_SYMBOL(mem_map); 85 #endif 86 87 /* 88 * A number of key systems in x86 including ioremap() rely on the assumption 89 * that high_memory defines the upper bound on direct map memory, then end 90 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 91 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 92 * and ZONE_HIGHMEM. 93 */ 94 void * high_memory; 95 96 EXPORT_SYMBOL(high_memory); 97 98 /* 99 * Randomize the address space (stacks, mmaps, brk, etc.). 100 * 101 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 102 * as ancient (libc5 based) binaries can segfault. ) 103 */ 104 int randomize_va_space __read_mostly = 105 #ifdef CONFIG_COMPAT_BRK 106 1; 107 #else 108 2; 109 #endif 110 111 static int __init disable_randmaps(char *s) 112 { 113 randomize_va_space = 0; 114 return 1; 115 } 116 __setup("norandmaps", disable_randmaps); 117 118 unsigned long zero_pfn __read_mostly; 119 unsigned long highest_memmap_pfn __read_mostly; 120 121 EXPORT_SYMBOL(zero_pfn); 122 123 /* 124 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 125 */ 126 static int __init init_zero_pfn(void) 127 { 128 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 129 return 0; 130 } 131 core_initcall(init_zero_pfn); 132 133 134 #if defined(SPLIT_RSS_COUNTING) 135 136 void sync_mm_rss(struct mm_struct *mm) 137 { 138 int i; 139 140 for (i = 0; i < NR_MM_COUNTERS; i++) { 141 if (current->rss_stat.count[i]) { 142 add_mm_counter(mm, i, current->rss_stat.count[i]); 143 current->rss_stat.count[i] = 0; 144 } 145 } 146 current->rss_stat.events = 0; 147 } 148 149 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 150 { 151 struct task_struct *task = current; 152 153 if (likely(task->mm == mm)) 154 task->rss_stat.count[member] += val; 155 else 156 add_mm_counter(mm, member, val); 157 } 158 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 159 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 160 161 /* sync counter once per 64 page faults */ 162 #define TASK_RSS_EVENTS_THRESH (64) 163 static void check_sync_rss_stat(struct task_struct *task) 164 { 165 if (unlikely(task != current)) 166 return; 167 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 168 sync_mm_rss(task->mm); 169 } 170 #else /* SPLIT_RSS_COUNTING */ 171 172 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 173 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 174 175 static void check_sync_rss_stat(struct task_struct *task) 176 { 177 } 178 179 #endif /* SPLIT_RSS_COUNTING */ 180 181 #ifdef HAVE_GENERIC_MMU_GATHER 182 183 static int tlb_next_batch(struct mmu_gather *tlb) 184 { 185 struct mmu_gather_batch *batch; 186 187 batch = tlb->active; 188 if (batch->next) { 189 tlb->active = batch->next; 190 return 1; 191 } 192 193 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT) 194 return 0; 195 196 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); 197 if (!batch) 198 return 0; 199 200 tlb->batch_count++; 201 batch->next = NULL; 202 batch->nr = 0; 203 batch->max = MAX_GATHER_BATCH; 204 205 tlb->active->next = batch; 206 tlb->active = batch; 207 208 return 1; 209 } 210 211 /* tlb_gather_mmu 212 * Called to initialize an (on-stack) mmu_gather structure for page-table 213 * tear-down from @mm. The @fullmm argument is used when @mm is without 214 * users and we're going to destroy the full address space (exit/execve). 215 */ 216 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end) 217 { 218 tlb->mm = mm; 219 220 /* Is it from 0 to ~0? */ 221 tlb->fullmm = !(start | (end+1)); 222 tlb->need_flush_all = 0; 223 tlb->start = start; 224 tlb->end = end; 225 tlb->need_flush = 0; 226 tlb->local.next = NULL; 227 tlb->local.nr = 0; 228 tlb->local.max = ARRAY_SIZE(tlb->__pages); 229 tlb->active = &tlb->local; 230 tlb->batch_count = 0; 231 232 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 233 tlb->batch = NULL; 234 #endif 235 } 236 237 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb) 238 { 239 tlb->need_flush = 0; 240 tlb_flush(tlb); 241 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 242 tlb_table_flush(tlb); 243 #endif 244 } 245 246 static void tlb_flush_mmu_free(struct mmu_gather *tlb) 247 { 248 struct mmu_gather_batch *batch; 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 void tlb_flush_mmu(struct mmu_gather *tlb) 258 { 259 if (!tlb->need_flush) 260 return; 261 tlb_flush_mmu_tlbonly(tlb); 262 tlb_flush_mmu_free(tlb); 263 } 264 265 /* tlb_finish_mmu 266 * Called at the end of the shootdown operation to free up any resources 267 * that were required. 268 */ 269 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) 270 { 271 struct mmu_gather_batch *batch, *next; 272 273 tlb_flush_mmu(tlb); 274 275 /* keep the page table cache within bounds */ 276 check_pgt_cache(); 277 278 for (batch = tlb->local.next; batch; batch = next) { 279 next = batch->next; 280 free_pages((unsigned long)batch, 0); 281 } 282 tlb->local.next = NULL; 283 } 284 285 /* __tlb_remove_page 286 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while 287 * handling the additional races in SMP caused by other CPUs caching valid 288 * mappings in their TLBs. Returns the number of free page slots left. 289 * When out of page slots we must call tlb_flush_mmu(). 290 */ 291 int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) 292 { 293 struct mmu_gather_batch *batch; 294 295 VM_BUG_ON(!tlb->need_flush); 296 297 batch = tlb->active; 298 batch->pages[batch->nr++] = page; 299 if (batch->nr == batch->max) { 300 if (!tlb_next_batch(tlb)) 301 return 0; 302 batch = tlb->active; 303 } 304 VM_BUG_ON_PAGE(batch->nr > batch->max, page); 305 306 return batch->max - batch->nr; 307 } 308 309 #endif /* HAVE_GENERIC_MMU_GATHER */ 310 311 #ifdef CONFIG_HAVE_RCU_TABLE_FREE 312 313 /* 314 * See the comment near struct mmu_table_batch. 315 */ 316 317 static void tlb_remove_table_smp_sync(void *arg) 318 { 319 /* Simply deliver the interrupt */ 320 } 321 322 static void tlb_remove_table_one(void *table) 323 { 324 /* 325 * This isn't an RCU grace period and hence the page-tables cannot be 326 * assumed to be actually RCU-freed. 327 * 328 * It is however sufficient for software page-table walkers that rely on 329 * IRQ disabling. See the comment near struct mmu_table_batch. 330 */ 331 smp_call_function(tlb_remove_table_smp_sync, NULL, 1); 332 __tlb_remove_table(table); 333 } 334 335 static void tlb_remove_table_rcu(struct rcu_head *head) 336 { 337 struct mmu_table_batch *batch; 338 int i; 339 340 batch = container_of(head, struct mmu_table_batch, rcu); 341 342 for (i = 0; i < batch->nr; i++) 343 __tlb_remove_table(batch->tables[i]); 344 345 free_page((unsigned long)batch); 346 } 347 348 void tlb_table_flush(struct mmu_gather *tlb) 349 { 350 struct mmu_table_batch **batch = &tlb->batch; 351 352 if (*batch) { 353 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu); 354 *batch = NULL; 355 } 356 } 357 358 void tlb_remove_table(struct mmu_gather *tlb, void *table) 359 { 360 struct mmu_table_batch **batch = &tlb->batch; 361 362 tlb->need_flush = 1; 363 364 /* 365 * When there's less then two users of this mm there cannot be a 366 * concurrent page-table walk. 367 */ 368 if (atomic_read(&tlb->mm->mm_users) < 2) { 369 __tlb_remove_table(table); 370 return; 371 } 372 373 if (*batch == NULL) { 374 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN); 375 if (*batch == NULL) { 376 tlb_remove_table_one(table); 377 return; 378 } 379 (*batch)->nr = 0; 380 } 381 (*batch)->tables[(*batch)->nr++] = table; 382 if ((*batch)->nr == MAX_TABLE_BATCH) 383 tlb_table_flush(tlb); 384 } 385 386 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */ 387 388 /* 389 * Note: this doesn't free the actual pages themselves. That 390 * has been handled earlier when unmapping all the memory regions. 391 */ 392 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 393 unsigned long addr) 394 { 395 pgtable_t token = pmd_pgtable(*pmd); 396 pmd_clear(pmd); 397 pte_free_tlb(tlb, token, addr); 398 atomic_long_dec(&tlb->mm->nr_ptes); 399 } 400 401 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 402 unsigned long addr, unsigned long end, 403 unsigned long floor, unsigned long ceiling) 404 { 405 pmd_t *pmd; 406 unsigned long next; 407 unsigned long start; 408 409 start = addr; 410 pmd = pmd_offset(pud, addr); 411 do { 412 next = pmd_addr_end(addr, end); 413 if (pmd_none_or_clear_bad(pmd)) 414 continue; 415 free_pte_range(tlb, pmd, addr); 416 } while (pmd++, addr = next, addr != end); 417 418 start &= PUD_MASK; 419 if (start < floor) 420 return; 421 if (ceiling) { 422 ceiling &= PUD_MASK; 423 if (!ceiling) 424 return; 425 } 426 if (end - 1 > ceiling - 1) 427 return; 428 429 pmd = pmd_offset(pud, start); 430 pud_clear(pud); 431 pmd_free_tlb(tlb, pmd, start); 432 } 433 434 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 435 unsigned long addr, unsigned long end, 436 unsigned long floor, unsigned long ceiling) 437 { 438 pud_t *pud; 439 unsigned long next; 440 unsigned long start; 441 442 start = addr; 443 pud = pud_offset(pgd, addr); 444 do { 445 next = pud_addr_end(addr, end); 446 if (pud_none_or_clear_bad(pud)) 447 continue; 448 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 449 } while (pud++, addr = next, addr != end); 450 451 start &= PGDIR_MASK; 452 if (start < floor) 453 return; 454 if (ceiling) { 455 ceiling &= PGDIR_MASK; 456 if (!ceiling) 457 return; 458 } 459 if (end - 1 > ceiling - 1) 460 return; 461 462 pud = pud_offset(pgd, start); 463 pgd_clear(pgd); 464 pud_free_tlb(tlb, pud, start); 465 } 466 467 /* 468 * This function frees user-level page tables of a process. 469 */ 470 void free_pgd_range(struct mmu_gather *tlb, 471 unsigned long addr, unsigned long end, 472 unsigned long floor, unsigned long ceiling) 473 { 474 pgd_t *pgd; 475 unsigned long next; 476 477 /* 478 * The next few lines have given us lots of grief... 479 * 480 * Why are we testing PMD* at this top level? Because often 481 * there will be no work to do at all, and we'd prefer not to 482 * go all the way down to the bottom just to discover that. 483 * 484 * Why all these "- 1"s? Because 0 represents both the bottom 485 * of the address space and the top of it (using -1 for the 486 * top wouldn't help much: the masks would do the wrong thing). 487 * The rule is that addr 0 and floor 0 refer to the bottom of 488 * the address space, but end 0 and ceiling 0 refer to the top 489 * Comparisons need to use "end - 1" and "ceiling - 1" (though 490 * that end 0 case should be mythical). 491 * 492 * Wherever addr is brought up or ceiling brought down, we must 493 * be careful to reject "the opposite 0" before it confuses the 494 * subsequent tests. But what about where end is brought down 495 * by PMD_SIZE below? no, end can't go down to 0 there. 496 * 497 * Whereas we round start (addr) and ceiling down, by different 498 * masks at different levels, in order to test whether a table 499 * now has no other vmas using it, so can be freed, we don't 500 * bother to round floor or end up - the tests don't need that. 501 */ 502 503 addr &= PMD_MASK; 504 if (addr < floor) { 505 addr += PMD_SIZE; 506 if (!addr) 507 return; 508 } 509 if (ceiling) { 510 ceiling &= PMD_MASK; 511 if (!ceiling) 512 return; 513 } 514 if (end - 1 > ceiling - 1) 515 end -= PMD_SIZE; 516 if (addr > end - 1) 517 return; 518 519 pgd = pgd_offset(tlb->mm, addr); 520 do { 521 next = pgd_addr_end(addr, end); 522 if (pgd_none_or_clear_bad(pgd)) 523 continue; 524 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 525 } while (pgd++, addr = next, addr != end); 526 } 527 528 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 529 unsigned long floor, unsigned long ceiling) 530 { 531 while (vma) { 532 struct vm_area_struct *next = vma->vm_next; 533 unsigned long addr = vma->vm_start; 534 535 /* 536 * Hide vma from rmap and truncate_pagecache before freeing 537 * pgtables 538 */ 539 unlink_anon_vmas(vma); 540 unlink_file_vma(vma); 541 542 if (is_vm_hugetlb_page(vma)) { 543 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 544 floor, next? next->vm_start: ceiling); 545 } else { 546 /* 547 * Optimization: gather nearby vmas into one call down 548 */ 549 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 550 && !is_vm_hugetlb_page(next)) { 551 vma = next; 552 next = vma->vm_next; 553 unlink_anon_vmas(vma); 554 unlink_file_vma(vma); 555 } 556 free_pgd_range(tlb, addr, vma->vm_end, 557 floor, next? next->vm_start: ceiling); 558 } 559 vma = next; 560 } 561 } 562 563 int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, 564 pmd_t *pmd, unsigned long address) 565 { 566 spinlock_t *ptl; 567 pgtable_t new = pte_alloc_one(mm, address); 568 int wait_split_huge_page; 569 if (!new) 570 return -ENOMEM; 571 572 /* 573 * Ensure all pte setup (eg. pte page lock and page clearing) are 574 * visible before the pte is made visible to other CPUs by being 575 * put into page tables. 576 * 577 * The other side of the story is the pointer chasing in the page 578 * table walking code (when walking the page table without locking; 579 * ie. most of the time). Fortunately, these data accesses consist 580 * of a chain of data-dependent loads, meaning most CPUs (alpha 581 * being the notable exception) will already guarantee loads are 582 * seen in-order. See the alpha page table accessors for the 583 * smp_read_barrier_depends() barriers in page table walking code. 584 */ 585 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 586 587 ptl = pmd_lock(mm, pmd); 588 wait_split_huge_page = 0; 589 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 590 atomic_long_inc(&mm->nr_ptes); 591 pmd_populate(mm, pmd, new); 592 new = NULL; 593 } else if (unlikely(pmd_trans_splitting(*pmd))) 594 wait_split_huge_page = 1; 595 spin_unlock(ptl); 596 if (new) 597 pte_free(mm, new); 598 if (wait_split_huge_page) 599 wait_split_huge_page(vma->anon_vma, pmd); 600 return 0; 601 } 602 603 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 604 { 605 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 606 if (!new) 607 return -ENOMEM; 608 609 smp_wmb(); /* See comment in __pte_alloc */ 610 611 spin_lock(&init_mm.page_table_lock); 612 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 613 pmd_populate_kernel(&init_mm, pmd, new); 614 new = NULL; 615 } else 616 VM_BUG_ON(pmd_trans_splitting(*pmd)); 617 spin_unlock(&init_mm.page_table_lock); 618 if (new) 619 pte_free_kernel(&init_mm, new); 620 return 0; 621 } 622 623 static inline void init_rss_vec(int *rss) 624 { 625 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 626 } 627 628 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 629 { 630 int i; 631 632 if (current->mm == mm) 633 sync_mm_rss(mm); 634 for (i = 0; i < NR_MM_COUNTERS; i++) 635 if (rss[i]) 636 add_mm_counter(mm, i, rss[i]); 637 } 638 639 /* 640 * This function is called to print an error when a bad pte 641 * is found. For example, we might have a PFN-mapped pte in 642 * a region that doesn't allow it. 643 * 644 * The calling function must still handle the error. 645 */ 646 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 647 pte_t pte, struct page *page) 648 { 649 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 650 pud_t *pud = pud_offset(pgd, addr); 651 pmd_t *pmd = pmd_offset(pud, addr); 652 struct address_space *mapping; 653 pgoff_t index; 654 static unsigned long resume; 655 static unsigned long nr_shown; 656 static unsigned long nr_unshown; 657 658 /* 659 * Allow a burst of 60 reports, then keep quiet for that minute; 660 * or allow a steady drip of one report per second. 661 */ 662 if (nr_shown == 60) { 663 if (time_before(jiffies, resume)) { 664 nr_unshown++; 665 return; 666 } 667 if (nr_unshown) { 668 printk(KERN_ALERT 669 "BUG: Bad page map: %lu messages suppressed\n", 670 nr_unshown); 671 nr_unshown = 0; 672 } 673 nr_shown = 0; 674 } 675 if (nr_shown++ == 0) 676 resume = jiffies + 60 * HZ; 677 678 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 679 index = linear_page_index(vma, addr); 680 681 printk(KERN_ALERT 682 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 683 current->comm, 684 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 685 if (page) 686 dump_page(page, "bad pte"); 687 printk(KERN_ALERT 688 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 689 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 690 /* 691 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 692 */ 693 if (vma->vm_ops) 694 printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n", 695 vma->vm_ops->fault); 696 if (vma->vm_file) 697 printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n", 698 vma->vm_file->f_op->mmap); 699 dump_stack(); 700 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); 701 } 702 703 /* 704 * vm_normal_page -- This function gets the "struct page" associated with a pte. 705 * 706 * "Special" mappings do not wish to be associated with a "struct page" (either 707 * it doesn't exist, or it exists but they don't want to touch it). In this 708 * case, NULL is returned here. "Normal" mappings do have a struct page. 709 * 710 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 711 * pte bit, in which case this function is trivial. Secondly, an architecture 712 * may not have a spare pte bit, which requires a more complicated scheme, 713 * described below. 714 * 715 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 716 * special mapping (even if there are underlying and valid "struct pages"). 717 * COWed pages of a VM_PFNMAP are always normal. 718 * 719 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 720 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 721 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 722 * mapping will always honor the rule 723 * 724 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 725 * 726 * And for normal mappings this is false. 727 * 728 * This restricts such mappings to be a linear translation from virtual address 729 * to pfn. To get around this restriction, we allow arbitrary mappings so long 730 * as the vma is not a COW mapping; in that case, we know that all ptes are 731 * special (because none can have been COWed). 732 * 733 * 734 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 735 * 736 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 737 * page" backing, however the difference is that _all_ pages with a struct 738 * page (that is, those where pfn_valid is true) are refcounted and considered 739 * normal pages by the VM. The disadvantage is that pages are refcounted 740 * (which can be slower and simply not an option for some PFNMAP users). The 741 * advantage is that we don't have to follow the strict linearity rule of 742 * PFNMAP mappings in order to support COWable mappings. 743 * 744 */ 745 #ifdef __HAVE_ARCH_PTE_SPECIAL 746 # define HAVE_PTE_SPECIAL 1 747 #else 748 # define HAVE_PTE_SPECIAL 0 749 #endif 750 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 751 pte_t pte) 752 { 753 unsigned long pfn = pte_pfn(pte); 754 755 if (HAVE_PTE_SPECIAL) { 756 if (likely(!pte_special(pte))) 757 goto check_pfn; 758 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 759 return NULL; 760 if (!is_zero_pfn(pfn)) 761 print_bad_pte(vma, addr, pte, NULL); 762 return NULL; 763 } 764 765 /* !HAVE_PTE_SPECIAL case follows: */ 766 767 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 768 if (vma->vm_flags & VM_MIXEDMAP) { 769 if (!pfn_valid(pfn)) 770 return NULL; 771 goto out; 772 } else { 773 unsigned long off; 774 off = (addr - vma->vm_start) >> PAGE_SHIFT; 775 if (pfn == vma->vm_pgoff + off) 776 return NULL; 777 if (!is_cow_mapping(vma->vm_flags)) 778 return NULL; 779 } 780 } 781 782 if (is_zero_pfn(pfn)) 783 return NULL; 784 check_pfn: 785 if (unlikely(pfn > highest_memmap_pfn)) { 786 print_bad_pte(vma, addr, pte, NULL); 787 return NULL; 788 } 789 790 /* 791 * NOTE! We still have PageReserved() pages in the page tables. 792 * eg. VDSO mappings can cause them to exist. 793 */ 794 out: 795 return pfn_to_page(pfn); 796 } 797 798 /* 799 * copy one vm_area from one task to the other. Assumes the page tables 800 * already present in the new task to be cleared in the whole range 801 * covered by this vma. 802 */ 803 804 static inline unsigned long 805 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 806 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 807 unsigned long addr, int *rss) 808 { 809 unsigned long vm_flags = vma->vm_flags; 810 pte_t pte = *src_pte; 811 struct page *page; 812 813 /* pte contains position in swap or file, so copy. */ 814 if (unlikely(!pte_present(pte))) { 815 if (!pte_file(pte)) { 816 swp_entry_t entry = pte_to_swp_entry(pte); 817 818 if (swap_duplicate(entry) < 0) 819 return entry.val; 820 821 /* make sure dst_mm is on swapoff's mmlist. */ 822 if (unlikely(list_empty(&dst_mm->mmlist))) { 823 spin_lock(&mmlist_lock); 824 if (list_empty(&dst_mm->mmlist)) 825 list_add(&dst_mm->mmlist, 826 &src_mm->mmlist); 827 spin_unlock(&mmlist_lock); 828 } 829 if (likely(!non_swap_entry(entry))) 830 rss[MM_SWAPENTS]++; 831 else if (is_migration_entry(entry)) { 832 page = migration_entry_to_page(entry); 833 834 if (PageAnon(page)) 835 rss[MM_ANONPAGES]++; 836 else 837 rss[MM_FILEPAGES]++; 838 839 if (is_write_migration_entry(entry) && 840 is_cow_mapping(vm_flags)) { 841 /* 842 * COW mappings require pages in both 843 * parent and child to be set to read. 844 */ 845 make_migration_entry_read(&entry); 846 pte = swp_entry_to_pte(entry); 847 if (pte_swp_soft_dirty(*src_pte)) 848 pte = pte_swp_mksoft_dirty(pte); 849 set_pte_at(src_mm, addr, src_pte, pte); 850 } 851 } 852 } 853 goto out_set_pte; 854 } 855 856 /* 857 * If it's a COW mapping, write protect it both 858 * in the parent and the child 859 */ 860 if (is_cow_mapping(vm_flags)) { 861 ptep_set_wrprotect(src_mm, addr, src_pte); 862 pte = pte_wrprotect(pte); 863 } 864 865 /* 866 * If it's a shared mapping, mark it clean in 867 * the child 868 */ 869 if (vm_flags & VM_SHARED) 870 pte = pte_mkclean(pte); 871 pte = pte_mkold(pte); 872 873 page = vm_normal_page(vma, addr, pte); 874 if (page) { 875 get_page(page); 876 page_dup_rmap(page); 877 if (PageAnon(page)) 878 rss[MM_ANONPAGES]++; 879 else 880 rss[MM_FILEPAGES]++; 881 } 882 883 out_set_pte: 884 set_pte_at(dst_mm, addr, dst_pte, pte); 885 return 0; 886 } 887 888 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 889 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 890 unsigned long addr, unsigned long end) 891 { 892 pte_t *orig_src_pte, *orig_dst_pte; 893 pte_t *src_pte, *dst_pte; 894 spinlock_t *src_ptl, *dst_ptl; 895 int progress = 0; 896 int rss[NR_MM_COUNTERS]; 897 swp_entry_t entry = (swp_entry_t){0}; 898 899 again: 900 init_rss_vec(rss); 901 902 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 903 if (!dst_pte) 904 return -ENOMEM; 905 src_pte = pte_offset_map(src_pmd, addr); 906 src_ptl = pte_lockptr(src_mm, src_pmd); 907 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 908 orig_src_pte = src_pte; 909 orig_dst_pte = dst_pte; 910 arch_enter_lazy_mmu_mode(); 911 912 do { 913 /* 914 * We are holding two locks at this point - either of them 915 * could generate latencies in another task on another CPU. 916 */ 917 if (progress >= 32) { 918 progress = 0; 919 if (need_resched() || 920 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 921 break; 922 } 923 if (pte_none(*src_pte)) { 924 progress++; 925 continue; 926 } 927 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 928 vma, addr, rss); 929 if (entry.val) 930 break; 931 progress += 8; 932 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 933 934 arch_leave_lazy_mmu_mode(); 935 spin_unlock(src_ptl); 936 pte_unmap(orig_src_pte); 937 add_mm_rss_vec(dst_mm, rss); 938 pte_unmap_unlock(orig_dst_pte, dst_ptl); 939 cond_resched(); 940 941 if (entry.val) { 942 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 943 return -ENOMEM; 944 progress = 0; 945 } 946 if (addr != end) 947 goto again; 948 return 0; 949 } 950 951 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 952 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 953 unsigned long addr, unsigned long end) 954 { 955 pmd_t *src_pmd, *dst_pmd; 956 unsigned long next; 957 958 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 959 if (!dst_pmd) 960 return -ENOMEM; 961 src_pmd = pmd_offset(src_pud, addr); 962 do { 963 next = pmd_addr_end(addr, end); 964 if (pmd_trans_huge(*src_pmd)) { 965 int err; 966 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); 967 err = copy_huge_pmd(dst_mm, src_mm, 968 dst_pmd, src_pmd, addr, vma); 969 if (err == -ENOMEM) 970 return -ENOMEM; 971 if (!err) 972 continue; 973 /* fall through */ 974 } 975 if (pmd_none_or_clear_bad(src_pmd)) 976 continue; 977 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 978 vma, addr, next)) 979 return -ENOMEM; 980 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 981 return 0; 982 } 983 984 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 985 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 986 unsigned long addr, unsigned long end) 987 { 988 pud_t *src_pud, *dst_pud; 989 unsigned long next; 990 991 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 992 if (!dst_pud) 993 return -ENOMEM; 994 src_pud = pud_offset(src_pgd, addr); 995 do { 996 next = pud_addr_end(addr, end); 997 if (pud_none_or_clear_bad(src_pud)) 998 continue; 999 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 1000 vma, addr, next)) 1001 return -ENOMEM; 1002 } while (dst_pud++, src_pud++, addr = next, addr != end); 1003 return 0; 1004 } 1005 1006 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 1007 struct vm_area_struct *vma) 1008 { 1009 pgd_t *src_pgd, *dst_pgd; 1010 unsigned long next; 1011 unsigned long addr = vma->vm_start; 1012 unsigned long end = vma->vm_end; 1013 unsigned long mmun_start; /* For mmu_notifiers */ 1014 unsigned long mmun_end; /* For mmu_notifiers */ 1015 bool is_cow; 1016 int ret; 1017 1018 /* 1019 * Don't copy ptes where a page fault will fill them correctly. 1020 * Fork becomes much lighter when there are big shared or private 1021 * readonly mappings. The tradeoff is that copy_page_range is more 1022 * efficient than faulting. 1023 */ 1024 if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR | 1025 VM_PFNMAP | VM_MIXEDMAP))) { 1026 if (!vma->anon_vma) 1027 return 0; 1028 } 1029 1030 if (is_vm_hugetlb_page(vma)) 1031 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 1032 1033 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 1034 /* 1035 * We do not free on error cases below as remove_vma 1036 * gets called on error from higher level routine 1037 */ 1038 ret = track_pfn_copy(vma); 1039 if (ret) 1040 return ret; 1041 } 1042 1043 /* 1044 * We need to invalidate the secondary MMU mappings only when 1045 * there could be a permission downgrade on the ptes of the 1046 * parent mm. And a permission downgrade will only happen if 1047 * is_cow_mapping() returns true. 1048 */ 1049 is_cow = is_cow_mapping(vma->vm_flags); 1050 mmun_start = addr; 1051 mmun_end = end; 1052 if (is_cow) 1053 mmu_notifier_invalidate_range_start(src_mm, mmun_start, 1054 mmun_end); 1055 1056 ret = 0; 1057 dst_pgd = pgd_offset(dst_mm, addr); 1058 src_pgd = pgd_offset(src_mm, addr); 1059 do { 1060 next = pgd_addr_end(addr, end); 1061 if (pgd_none_or_clear_bad(src_pgd)) 1062 continue; 1063 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 1064 vma, addr, next))) { 1065 ret = -ENOMEM; 1066 break; 1067 } 1068 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 1069 1070 if (is_cow) 1071 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end); 1072 return ret; 1073 } 1074 1075 static unsigned long zap_pte_range(struct mmu_gather *tlb, 1076 struct vm_area_struct *vma, pmd_t *pmd, 1077 unsigned long addr, unsigned long end, 1078 struct zap_details *details) 1079 { 1080 struct mm_struct *mm = tlb->mm; 1081 int force_flush = 0; 1082 int rss[NR_MM_COUNTERS]; 1083 spinlock_t *ptl; 1084 pte_t *start_pte; 1085 pte_t *pte; 1086 1087 again: 1088 init_rss_vec(rss); 1089 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 1090 pte = start_pte; 1091 arch_enter_lazy_mmu_mode(); 1092 do { 1093 pte_t ptent = *pte; 1094 if (pte_none(ptent)) { 1095 continue; 1096 } 1097 1098 if (pte_present(ptent)) { 1099 struct page *page; 1100 1101 page = vm_normal_page(vma, addr, ptent); 1102 if (unlikely(details) && page) { 1103 /* 1104 * unmap_shared_mapping_pages() wants to 1105 * invalidate cache without truncating: 1106 * unmap shared but keep private pages. 1107 */ 1108 if (details->check_mapping && 1109 details->check_mapping != page->mapping) 1110 continue; 1111 /* 1112 * Each page->index must be checked when 1113 * invalidating or truncating nonlinear. 1114 */ 1115 if (details->nonlinear_vma && 1116 (page->index < details->first_index || 1117 page->index > details->last_index)) 1118 continue; 1119 } 1120 ptent = ptep_get_and_clear_full(mm, addr, pte, 1121 tlb->fullmm); 1122 tlb_remove_tlb_entry(tlb, pte, addr); 1123 if (unlikely(!page)) 1124 continue; 1125 if (unlikely(details) && details->nonlinear_vma 1126 && linear_page_index(details->nonlinear_vma, 1127 addr) != page->index) { 1128 pte_t ptfile = pgoff_to_pte(page->index); 1129 if (pte_soft_dirty(ptent)) 1130 ptfile = pte_file_mksoft_dirty(ptfile); 1131 set_pte_at(mm, addr, pte, ptfile); 1132 } 1133 if (PageAnon(page)) 1134 rss[MM_ANONPAGES]--; 1135 else { 1136 if (pte_dirty(ptent)) { 1137 force_flush = 1; 1138 set_page_dirty(page); 1139 } 1140 if (pte_young(ptent) && 1141 likely(!(vma->vm_flags & VM_SEQ_READ))) 1142 mark_page_accessed(page); 1143 rss[MM_FILEPAGES]--; 1144 } 1145 page_remove_rmap(page); 1146 if (unlikely(page_mapcount(page) < 0)) 1147 print_bad_pte(vma, addr, ptent, page); 1148 if (unlikely(!__tlb_remove_page(tlb, page))) { 1149 force_flush = 1; 1150 break; 1151 } 1152 continue; 1153 } 1154 /* 1155 * If details->check_mapping, we leave swap entries; 1156 * if details->nonlinear_vma, we leave file entries. 1157 */ 1158 if (unlikely(details)) 1159 continue; 1160 if (pte_file(ptent)) { 1161 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 1162 print_bad_pte(vma, addr, ptent, NULL); 1163 } else { 1164 swp_entry_t entry = pte_to_swp_entry(ptent); 1165 1166 if (!non_swap_entry(entry)) 1167 rss[MM_SWAPENTS]--; 1168 else if (is_migration_entry(entry)) { 1169 struct page *page; 1170 1171 page = migration_entry_to_page(entry); 1172 1173 if (PageAnon(page)) 1174 rss[MM_ANONPAGES]--; 1175 else 1176 rss[MM_FILEPAGES]--; 1177 } 1178 if (unlikely(!free_swap_and_cache(entry))) 1179 print_bad_pte(vma, addr, ptent, NULL); 1180 } 1181 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 1182 } while (pte++, addr += PAGE_SIZE, addr != end); 1183 1184 add_mm_rss_vec(mm, rss); 1185 arch_leave_lazy_mmu_mode(); 1186 1187 /* Do the actual TLB flush before dropping ptl */ 1188 if (force_flush) { 1189 unsigned long old_end; 1190 1191 /* 1192 * Flush the TLB just for the previous segment, 1193 * then update the range to be the remaining 1194 * TLB range. 1195 */ 1196 old_end = tlb->end; 1197 tlb->end = addr; 1198 tlb_flush_mmu_tlbonly(tlb); 1199 tlb->start = addr; 1200 tlb->end = old_end; 1201 } 1202 pte_unmap_unlock(start_pte, ptl); 1203 1204 /* 1205 * If we forced a TLB flush (either due to running out of 1206 * batch buffers or because we needed to flush dirty TLB 1207 * entries before releasing the ptl), free the batched 1208 * memory too. Restart if we didn't do everything. 1209 */ 1210 if (force_flush) { 1211 force_flush = 0; 1212 tlb_flush_mmu_free(tlb); 1213 1214 if (addr != end) 1215 goto again; 1216 } 1217 1218 return addr; 1219 } 1220 1221 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1222 struct vm_area_struct *vma, pud_t *pud, 1223 unsigned long addr, unsigned long end, 1224 struct zap_details *details) 1225 { 1226 pmd_t *pmd; 1227 unsigned long next; 1228 1229 pmd = pmd_offset(pud, addr); 1230 do { 1231 next = pmd_addr_end(addr, end); 1232 if (pmd_trans_huge(*pmd)) { 1233 if (next - addr != HPAGE_PMD_SIZE) { 1234 #ifdef CONFIG_DEBUG_VM 1235 if (!rwsem_is_locked(&tlb->mm->mmap_sem)) { 1236 pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n", 1237 __func__, addr, end, 1238 vma->vm_start, 1239 vma->vm_end); 1240 BUG(); 1241 } 1242 #endif 1243 split_huge_page_pmd(vma, addr, pmd); 1244 } else if (zap_huge_pmd(tlb, vma, pmd, addr)) 1245 goto next; 1246 /* fall through */ 1247 } 1248 /* 1249 * Here there can be other concurrent MADV_DONTNEED or 1250 * trans huge page faults running, and if the pmd is 1251 * none or trans huge it can change under us. This is 1252 * because MADV_DONTNEED holds the mmap_sem in read 1253 * mode. 1254 */ 1255 if (pmd_none_or_trans_huge_or_clear_bad(pmd)) 1256 goto next; 1257 next = zap_pte_range(tlb, vma, pmd, addr, next, details); 1258 next: 1259 cond_resched(); 1260 } while (pmd++, addr = next, addr != end); 1261 1262 return addr; 1263 } 1264 1265 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1266 struct vm_area_struct *vma, pgd_t *pgd, 1267 unsigned long addr, unsigned long end, 1268 struct zap_details *details) 1269 { 1270 pud_t *pud; 1271 unsigned long next; 1272 1273 pud = pud_offset(pgd, addr); 1274 do { 1275 next = pud_addr_end(addr, end); 1276 if (pud_none_or_clear_bad(pud)) 1277 continue; 1278 next = zap_pmd_range(tlb, vma, pud, addr, next, details); 1279 } while (pud++, addr = next, addr != end); 1280 1281 return addr; 1282 } 1283 1284 static void unmap_page_range(struct mmu_gather *tlb, 1285 struct vm_area_struct *vma, 1286 unsigned long addr, unsigned long end, 1287 struct zap_details *details) 1288 { 1289 pgd_t *pgd; 1290 unsigned long next; 1291 1292 if (details && !details->check_mapping && !details->nonlinear_vma) 1293 details = NULL; 1294 1295 BUG_ON(addr >= end); 1296 tlb_start_vma(tlb, vma); 1297 pgd = pgd_offset(vma->vm_mm, addr); 1298 do { 1299 next = pgd_addr_end(addr, end); 1300 if (pgd_none_or_clear_bad(pgd)) 1301 continue; 1302 next = zap_pud_range(tlb, vma, pgd, addr, next, details); 1303 } while (pgd++, addr = next, addr != end); 1304 tlb_end_vma(tlb, vma); 1305 } 1306 1307 1308 static void unmap_single_vma(struct mmu_gather *tlb, 1309 struct vm_area_struct *vma, unsigned long start_addr, 1310 unsigned long end_addr, 1311 struct zap_details *details) 1312 { 1313 unsigned long start = max(vma->vm_start, start_addr); 1314 unsigned long end; 1315 1316 if (start >= vma->vm_end) 1317 return; 1318 end = min(vma->vm_end, end_addr); 1319 if (end <= vma->vm_start) 1320 return; 1321 1322 if (vma->vm_file) 1323 uprobe_munmap(vma, start, end); 1324 1325 if (unlikely(vma->vm_flags & VM_PFNMAP)) 1326 untrack_pfn(vma, 0, 0); 1327 1328 if (start != end) { 1329 if (unlikely(is_vm_hugetlb_page(vma))) { 1330 /* 1331 * It is undesirable to test vma->vm_file as it 1332 * should be non-null for valid hugetlb area. 1333 * However, vm_file will be NULL in the error 1334 * cleanup path of mmap_region. When 1335 * hugetlbfs ->mmap method fails, 1336 * mmap_region() nullifies vma->vm_file 1337 * before calling this function to clean up. 1338 * Since no pte has actually been setup, it is 1339 * safe to do nothing in this case. 1340 */ 1341 if (vma->vm_file) { 1342 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex); 1343 __unmap_hugepage_range_final(tlb, vma, start, end, NULL); 1344 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex); 1345 } 1346 } else 1347 unmap_page_range(tlb, vma, start, end, details); 1348 } 1349 } 1350 1351 /** 1352 * unmap_vmas - unmap a range of memory covered by a list of vma's 1353 * @tlb: address of the caller's struct mmu_gather 1354 * @vma: the starting vma 1355 * @start_addr: virtual address at which to start unmapping 1356 * @end_addr: virtual address at which to end unmapping 1357 * 1358 * Unmap all pages in the vma list. 1359 * 1360 * Only addresses between `start' and `end' will be unmapped. 1361 * 1362 * The VMA list must be sorted in ascending virtual address order. 1363 * 1364 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1365 * range after unmap_vmas() returns. So the only responsibility here is to 1366 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1367 * drops the lock and schedules. 1368 */ 1369 void unmap_vmas(struct mmu_gather *tlb, 1370 struct vm_area_struct *vma, unsigned long start_addr, 1371 unsigned long end_addr) 1372 { 1373 struct mm_struct *mm = vma->vm_mm; 1374 1375 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1376 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) 1377 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL); 1378 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1379 } 1380 1381 /** 1382 * zap_page_range - remove user pages in a given range 1383 * @vma: vm_area_struct holding the applicable pages 1384 * @start: starting address of pages to zap 1385 * @size: number of bytes to zap 1386 * @details: details of nonlinear truncation or shared cache invalidation 1387 * 1388 * Caller must protect the VMA list 1389 */ 1390 void zap_page_range(struct vm_area_struct *vma, unsigned long start, 1391 unsigned long size, struct zap_details *details) 1392 { 1393 struct mm_struct *mm = vma->vm_mm; 1394 struct mmu_gather tlb; 1395 unsigned long end = start + size; 1396 1397 lru_add_drain(); 1398 tlb_gather_mmu(&tlb, mm, start, end); 1399 update_hiwater_rss(mm); 1400 mmu_notifier_invalidate_range_start(mm, start, end); 1401 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) 1402 unmap_single_vma(&tlb, vma, start, end, details); 1403 mmu_notifier_invalidate_range_end(mm, start, end); 1404 tlb_finish_mmu(&tlb, start, end); 1405 } 1406 1407 /** 1408 * zap_page_range_single - remove user pages in a given range 1409 * @vma: vm_area_struct holding the applicable pages 1410 * @address: starting address of pages to zap 1411 * @size: number of bytes to zap 1412 * @details: details of nonlinear truncation or shared cache invalidation 1413 * 1414 * The range must fit into one VMA. 1415 */ 1416 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 1417 unsigned long size, struct zap_details *details) 1418 { 1419 struct mm_struct *mm = vma->vm_mm; 1420 struct mmu_gather tlb; 1421 unsigned long end = address + size; 1422 1423 lru_add_drain(); 1424 tlb_gather_mmu(&tlb, mm, address, end); 1425 update_hiwater_rss(mm); 1426 mmu_notifier_invalidate_range_start(mm, address, end); 1427 unmap_single_vma(&tlb, vma, address, end, details); 1428 mmu_notifier_invalidate_range_end(mm, address, end); 1429 tlb_finish_mmu(&tlb, address, end); 1430 } 1431 1432 /** 1433 * zap_vma_ptes - remove ptes mapping the vma 1434 * @vma: vm_area_struct holding ptes to be zapped 1435 * @address: starting address of pages to zap 1436 * @size: number of bytes to zap 1437 * 1438 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1439 * 1440 * The entire address range must be fully contained within the vma. 1441 * 1442 * Returns 0 if successful. 1443 */ 1444 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1445 unsigned long size) 1446 { 1447 if (address < vma->vm_start || address + size > vma->vm_end || 1448 !(vma->vm_flags & VM_PFNMAP)) 1449 return -1; 1450 zap_page_range_single(vma, address, size, NULL); 1451 return 0; 1452 } 1453 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1454 1455 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 1456 spinlock_t **ptl) 1457 { 1458 pgd_t * pgd = pgd_offset(mm, addr); 1459 pud_t * pud = pud_alloc(mm, pgd, addr); 1460 if (pud) { 1461 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1462 if (pmd) { 1463 VM_BUG_ON(pmd_trans_huge(*pmd)); 1464 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1465 } 1466 } 1467 return NULL; 1468 } 1469 1470 /* 1471 * This is the old fallback for page remapping. 1472 * 1473 * For historical reasons, it only allows reserved pages. Only 1474 * old drivers should use this, and they needed to mark their 1475 * pages reserved for the old functions anyway. 1476 */ 1477 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1478 struct page *page, pgprot_t prot) 1479 { 1480 struct mm_struct *mm = vma->vm_mm; 1481 int retval; 1482 pte_t *pte; 1483 spinlock_t *ptl; 1484 1485 retval = -EINVAL; 1486 if (PageAnon(page)) 1487 goto out; 1488 retval = -ENOMEM; 1489 flush_dcache_page(page); 1490 pte = get_locked_pte(mm, addr, &ptl); 1491 if (!pte) 1492 goto out; 1493 retval = -EBUSY; 1494 if (!pte_none(*pte)) 1495 goto out_unlock; 1496 1497 /* Ok, finally just insert the thing.. */ 1498 get_page(page); 1499 inc_mm_counter_fast(mm, MM_FILEPAGES); 1500 page_add_file_rmap(page); 1501 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1502 1503 retval = 0; 1504 pte_unmap_unlock(pte, ptl); 1505 return retval; 1506 out_unlock: 1507 pte_unmap_unlock(pte, ptl); 1508 out: 1509 return retval; 1510 } 1511 1512 /** 1513 * vm_insert_page - insert single page into user vma 1514 * @vma: user vma to map to 1515 * @addr: target user address of this page 1516 * @page: source kernel page 1517 * 1518 * This allows drivers to insert individual pages they've allocated 1519 * into a user vma. 1520 * 1521 * The page has to be a nice clean _individual_ kernel allocation. 1522 * If you allocate a compound page, you need to have marked it as 1523 * such (__GFP_COMP), or manually just split the page up yourself 1524 * (see split_page()). 1525 * 1526 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1527 * took an arbitrary page protection parameter. This doesn't allow 1528 * that. Your vma protection will have to be set up correctly, which 1529 * means that if you want a shared writable mapping, you'd better 1530 * ask for a shared writable mapping! 1531 * 1532 * The page does not need to be reserved. 1533 * 1534 * Usually this function is called from f_op->mmap() handler 1535 * under mm->mmap_sem write-lock, so it can change vma->vm_flags. 1536 * Caller must set VM_MIXEDMAP on vma if it wants to call this 1537 * function from other places, for example from page-fault handler. 1538 */ 1539 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1540 struct page *page) 1541 { 1542 if (addr < vma->vm_start || addr >= vma->vm_end) 1543 return -EFAULT; 1544 if (!page_count(page)) 1545 return -EINVAL; 1546 if (!(vma->vm_flags & VM_MIXEDMAP)) { 1547 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem)); 1548 BUG_ON(vma->vm_flags & VM_PFNMAP); 1549 vma->vm_flags |= VM_MIXEDMAP; 1550 } 1551 return insert_page(vma, addr, page, vma->vm_page_prot); 1552 } 1553 EXPORT_SYMBOL(vm_insert_page); 1554 1555 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1556 unsigned long pfn, pgprot_t prot) 1557 { 1558 struct mm_struct *mm = vma->vm_mm; 1559 int retval; 1560 pte_t *pte, entry; 1561 spinlock_t *ptl; 1562 1563 retval = -ENOMEM; 1564 pte = get_locked_pte(mm, addr, &ptl); 1565 if (!pte) 1566 goto out; 1567 retval = -EBUSY; 1568 if (!pte_none(*pte)) 1569 goto out_unlock; 1570 1571 /* Ok, finally just insert the thing.. */ 1572 entry = pte_mkspecial(pfn_pte(pfn, prot)); 1573 set_pte_at(mm, addr, pte, entry); 1574 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 1575 1576 retval = 0; 1577 out_unlock: 1578 pte_unmap_unlock(pte, ptl); 1579 out: 1580 return retval; 1581 } 1582 1583 /** 1584 * vm_insert_pfn - insert single pfn into user vma 1585 * @vma: user vma to map to 1586 * @addr: target user address of this page 1587 * @pfn: source kernel pfn 1588 * 1589 * Similar to vm_insert_page, this allows drivers to insert individual pages 1590 * they've allocated into a user vma. Same comments apply. 1591 * 1592 * This function should only be called from a vm_ops->fault handler, and 1593 * in that case the handler should return NULL. 1594 * 1595 * vma cannot be a COW mapping. 1596 * 1597 * As this is called only for pages that do not currently exist, we 1598 * do not need to flush old virtual caches or the TLB. 1599 */ 1600 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1601 unsigned long pfn) 1602 { 1603 int ret; 1604 pgprot_t pgprot = vma->vm_page_prot; 1605 /* 1606 * Technically, architectures with pte_special can avoid all these 1607 * restrictions (same for remap_pfn_range). However we would like 1608 * consistency in testing and feature parity among all, so we should 1609 * try to keep these invariants in place for everybody. 1610 */ 1611 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 1612 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1613 (VM_PFNMAP|VM_MIXEDMAP)); 1614 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1615 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 1616 1617 if (addr < vma->vm_start || addr >= vma->vm_end) 1618 return -EFAULT; 1619 if (track_pfn_insert(vma, &pgprot, pfn)) 1620 return -EINVAL; 1621 1622 ret = insert_pfn(vma, addr, pfn, pgprot); 1623 1624 return ret; 1625 } 1626 EXPORT_SYMBOL(vm_insert_pfn); 1627 1628 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1629 unsigned long pfn) 1630 { 1631 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 1632 1633 if (addr < vma->vm_start || addr >= vma->vm_end) 1634 return -EFAULT; 1635 1636 /* 1637 * If we don't have pte special, then we have to use the pfn_valid() 1638 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 1639 * refcount the page if pfn_valid is true (hence insert_page rather 1640 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 1641 * without pte special, it would there be refcounted as a normal page. 1642 */ 1643 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 1644 struct page *page; 1645 1646 page = pfn_to_page(pfn); 1647 return insert_page(vma, addr, page, vma->vm_page_prot); 1648 } 1649 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 1650 } 1651 EXPORT_SYMBOL(vm_insert_mixed); 1652 1653 /* 1654 * maps a range of physical memory into the requested pages. the old 1655 * mappings are removed. any references to nonexistent pages results 1656 * in null mappings (currently treated as "copy-on-access") 1657 */ 1658 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1659 unsigned long addr, unsigned long end, 1660 unsigned long pfn, pgprot_t prot) 1661 { 1662 pte_t *pte; 1663 spinlock_t *ptl; 1664 1665 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1666 if (!pte) 1667 return -ENOMEM; 1668 arch_enter_lazy_mmu_mode(); 1669 do { 1670 BUG_ON(!pte_none(*pte)); 1671 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 1672 pfn++; 1673 } while (pte++, addr += PAGE_SIZE, addr != end); 1674 arch_leave_lazy_mmu_mode(); 1675 pte_unmap_unlock(pte - 1, ptl); 1676 return 0; 1677 } 1678 1679 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1680 unsigned long addr, unsigned long end, 1681 unsigned long pfn, pgprot_t prot) 1682 { 1683 pmd_t *pmd; 1684 unsigned long next; 1685 1686 pfn -= addr >> PAGE_SHIFT; 1687 pmd = pmd_alloc(mm, pud, addr); 1688 if (!pmd) 1689 return -ENOMEM; 1690 VM_BUG_ON(pmd_trans_huge(*pmd)); 1691 do { 1692 next = pmd_addr_end(addr, end); 1693 if (remap_pte_range(mm, pmd, addr, next, 1694 pfn + (addr >> PAGE_SHIFT), prot)) 1695 return -ENOMEM; 1696 } while (pmd++, addr = next, addr != end); 1697 return 0; 1698 } 1699 1700 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1701 unsigned long addr, unsigned long end, 1702 unsigned long pfn, pgprot_t prot) 1703 { 1704 pud_t *pud; 1705 unsigned long next; 1706 1707 pfn -= addr >> PAGE_SHIFT; 1708 pud = pud_alloc(mm, pgd, addr); 1709 if (!pud) 1710 return -ENOMEM; 1711 do { 1712 next = pud_addr_end(addr, end); 1713 if (remap_pmd_range(mm, pud, addr, next, 1714 pfn + (addr >> PAGE_SHIFT), prot)) 1715 return -ENOMEM; 1716 } while (pud++, addr = next, addr != end); 1717 return 0; 1718 } 1719 1720 /** 1721 * remap_pfn_range - remap kernel memory to userspace 1722 * @vma: user vma to map to 1723 * @addr: target user address to start at 1724 * @pfn: physical address of kernel memory 1725 * @size: size of map area 1726 * @prot: page protection flags for this mapping 1727 * 1728 * Note: this is only safe if the mm semaphore is held when called. 1729 */ 1730 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1731 unsigned long pfn, unsigned long size, pgprot_t prot) 1732 { 1733 pgd_t *pgd; 1734 unsigned long next; 1735 unsigned long end = addr + PAGE_ALIGN(size); 1736 struct mm_struct *mm = vma->vm_mm; 1737 int err; 1738 1739 /* 1740 * Physically remapped pages are special. Tell the 1741 * rest of the world about it: 1742 * VM_IO tells people not to look at these pages 1743 * (accesses can have side effects). 1744 * VM_PFNMAP tells the core MM that the base pages are just 1745 * raw PFN mappings, and do not have a "struct page" associated 1746 * with them. 1747 * VM_DONTEXPAND 1748 * Disable vma merging and expanding with mremap(). 1749 * VM_DONTDUMP 1750 * Omit vma from core dump, even when VM_IO turned off. 1751 * 1752 * There's a horrible special case to handle copy-on-write 1753 * behaviour that some programs depend on. We mark the "original" 1754 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1755 * See vm_normal_page() for details. 1756 */ 1757 if (is_cow_mapping(vma->vm_flags)) { 1758 if (addr != vma->vm_start || end != vma->vm_end) 1759 return -EINVAL; 1760 vma->vm_pgoff = pfn; 1761 } 1762 1763 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); 1764 if (err) 1765 return -EINVAL; 1766 1767 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 1768 1769 BUG_ON(addr >= end); 1770 pfn -= addr >> PAGE_SHIFT; 1771 pgd = pgd_offset(mm, addr); 1772 flush_cache_range(vma, addr, end); 1773 do { 1774 next = pgd_addr_end(addr, end); 1775 err = remap_pud_range(mm, pgd, addr, next, 1776 pfn + (addr >> PAGE_SHIFT), prot); 1777 if (err) 1778 break; 1779 } while (pgd++, addr = next, addr != end); 1780 1781 if (err) 1782 untrack_pfn(vma, pfn, PAGE_ALIGN(size)); 1783 1784 return err; 1785 } 1786 EXPORT_SYMBOL(remap_pfn_range); 1787 1788 /** 1789 * vm_iomap_memory - remap memory to userspace 1790 * @vma: user vma to map to 1791 * @start: start of area 1792 * @len: size of area 1793 * 1794 * This is a simplified io_remap_pfn_range() for common driver use. The 1795 * driver just needs to give us the physical memory range to be mapped, 1796 * we'll figure out the rest from the vma information. 1797 * 1798 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get 1799 * whatever write-combining details or similar. 1800 */ 1801 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 1802 { 1803 unsigned long vm_len, pfn, pages; 1804 1805 /* Check that the physical memory area passed in looks valid */ 1806 if (start + len < start) 1807 return -EINVAL; 1808 /* 1809 * You *really* shouldn't map things that aren't page-aligned, 1810 * but we've historically allowed it because IO memory might 1811 * just have smaller alignment. 1812 */ 1813 len += start & ~PAGE_MASK; 1814 pfn = start >> PAGE_SHIFT; 1815 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT; 1816 if (pfn + pages < pfn) 1817 return -EINVAL; 1818 1819 /* We start the mapping 'vm_pgoff' pages into the area */ 1820 if (vma->vm_pgoff > pages) 1821 return -EINVAL; 1822 pfn += vma->vm_pgoff; 1823 pages -= vma->vm_pgoff; 1824 1825 /* Can we fit all of the mapping? */ 1826 vm_len = vma->vm_end - vma->vm_start; 1827 if (vm_len >> PAGE_SHIFT > pages) 1828 return -EINVAL; 1829 1830 /* Ok, let it rip */ 1831 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 1832 } 1833 EXPORT_SYMBOL(vm_iomap_memory); 1834 1835 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 1836 unsigned long addr, unsigned long end, 1837 pte_fn_t fn, void *data) 1838 { 1839 pte_t *pte; 1840 int err; 1841 pgtable_t token; 1842 spinlock_t *uninitialized_var(ptl); 1843 1844 pte = (mm == &init_mm) ? 1845 pte_alloc_kernel(pmd, addr) : 1846 pte_alloc_map_lock(mm, pmd, addr, &ptl); 1847 if (!pte) 1848 return -ENOMEM; 1849 1850 BUG_ON(pmd_huge(*pmd)); 1851 1852 arch_enter_lazy_mmu_mode(); 1853 1854 token = pmd_pgtable(*pmd); 1855 1856 do { 1857 err = fn(pte++, token, addr, data); 1858 if (err) 1859 break; 1860 } while (addr += PAGE_SIZE, addr != end); 1861 1862 arch_leave_lazy_mmu_mode(); 1863 1864 if (mm != &init_mm) 1865 pte_unmap_unlock(pte-1, ptl); 1866 return err; 1867 } 1868 1869 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 1870 unsigned long addr, unsigned long end, 1871 pte_fn_t fn, void *data) 1872 { 1873 pmd_t *pmd; 1874 unsigned long next; 1875 int err; 1876 1877 BUG_ON(pud_huge(*pud)); 1878 1879 pmd = pmd_alloc(mm, pud, addr); 1880 if (!pmd) 1881 return -ENOMEM; 1882 do { 1883 next = pmd_addr_end(addr, end); 1884 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 1885 if (err) 1886 break; 1887 } while (pmd++, addr = next, addr != end); 1888 return err; 1889 } 1890 1891 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 1892 unsigned long addr, unsigned long end, 1893 pte_fn_t fn, void *data) 1894 { 1895 pud_t *pud; 1896 unsigned long next; 1897 int err; 1898 1899 pud = pud_alloc(mm, pgd, addr); 1900 if (!pud) 1901 return -ENOMEM; 1902 do { 1903 next = pud_addr_end(addr, end); 1904 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 1905 if (err) 1906 break; 1907 } while (pud++, addr = next, addr != end); 1908 return err; 1909 } 1910 1911 /* 1912 * Scan a region of virtual memory, filling in page tables as necessary 1913 * and calling a provided function on each leaf page table. 1914 */ 1915 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 1916 unsigned long size, pte_fn_t fn, void *data) 1917 { 1918 pgd_t *pgd; 1919 unsigned long next; 1920 unsigned long end = addr + size; 1921 int err; 1922 1923 BUG_ON(addr >= end); 1924 pgd = pgd_offset(mm, addr); 1925 do { 1926 next = pgd_addr_end(addr, end); 1927 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 1928 if (err) 1929 break; 1930 } while (pgd++, addr = next, addr != end); 1931 1932 return err; 1933 } 1934 EXPORT_SYMBOL_GPL(apply_to_page_range); 1935 1936 /* 1937 * handle_pte_fault chooses page fault handler according to an entry 1938 * which was read non-atomically. Before making any commitment, on 1939 * those architectures or configurations (e.g. i386 with PAE) which 1940 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault 1941 * must check under lock before unmapping the pte and proceeding 1942 * (but do_wp_page is only called after already making such a check; 1943 * and do_anonymous_page can safely check later on). 1944 */ 1945 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1946 pte_t *page_table, pte_t orig_pte) 1947 { 1948 int same = 1; 1949 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1950 if (sizeof(pte_t) > sizeof(unsigned long)) { 1951 spinlock_t *ptl = pte_lockptr(mm, pmd); 1952 spin_lock(ptl); 1953 same = pte_same(*page_table, orig_pte); 1954 spin_unlock(ptl); 1955 } 1956 #endif 1957 pte_unmap(page_table); 1958 return same; 1959 } 1960 1961 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1962 { 1963 debug_dma_assert_idle(src); 1964 1965 /* 1966 * If the source page was a PFN mapping, we don't have 1967 * a "struct page" for it. We do a best-effort copy by 1968 * just copying from the original user address. If that 1969 * fails, we just zero-fill it. Live with it. 1970 */ 1971 if (unlikely(!src)) { 1972 void *kaddr = kmap_atomic(dst); 1973 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1974 1975 /* 1976 * This really shouldn't fail, because the page is there 1977 * in the page tables. But it might just be unreadable, 1978 * in which case we just give up and fill the result with 1979 * zeroes. 1980 */ 1981 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1982 clear_page(kaddr); 1983 kunmap_atomic(kaddr); 1984 flush_dcache_page(dst); 1985 } else 1986 copy_user_highpage(dst, src, va, vma); 1987 } 1988 1989 /* 1990 * Notify the address space that the page is about to become writable so that 1991 * it can prohibit this or wait for the page to get into an appropriate state. 1992 * 1993 * We do this without the lock held, so that it can sleep if it needs to. 1994 */ 1995 static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page, 1996 unsigned long address) 1997 { 1998 struct vm_fault vmf; 1999 int ret; 2000 2001 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2002 vmf.pgoff = page->index; 2003 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2004 vmf.page = page; 2005 2006 ret = vma->vm_ops->page_mkwrite(vma, &vmf); 2007 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2008 return ret; 2009 if (unlikely(!(ret & VM_FAULT_LOCKED))) { 2010 lock_page(page); 2011 if (!page->mapping) { 2012 unlock_page(page); 2013 return 0; /* retry */ 2014 } 2015 ret |= VM_FAULT_LOCKED; 2016 } else 2017 VM_BUG_ON_PAGE(!PageLocked(page), page); 2018 return ret; 2019 } 2020 2021 /* 2022 * This routine handles present pages, when users try to write 2023 * to a shared page. It is done by copying the page to a new address 2024 * and decrementing the shared-page counter for the old page. 2025 * 2026 * Note that this routine assumes that the protection checks have been 2027 * done by the caller (the low-level page fault routine in most cases). 2028 * Thus we can safely just mark it writable once we've done any necessary 2029 * COW. 2030 * 2031 * We also mark the page dirty at this point even though the page will 2032 * change only once the write actually happens. This avoids a few races, 2033 * and potentially makes it more efficient. 2034 * 2035 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2036 * but allow concurrent faults), with pte both mapped and locked. 2037 * We return with mmap_sem still held, but pte unmapped and unlocked. 2038 */ 2039 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 2040 unsigned long address, pte_t *page_table, pmd_t *pmd, 2041 spinlock_t *ptl, pte_t orig_pte) 2042 __releases(ptl) 2043 { 2044 struct page *old_page, *new_page = NULL; 2045 pte_t entry; 2046 int ret = 0; 2047 int page_mkwrite = 0; 2048 struct page *dirty_page = NULL; 2049 unsigned long mmun_start = 0; /* For mmu_notifiers */ 2050 unsigned long mmun_end = 0; /* For mmu_notifiers */ 2051 struct mem_cgroup *memcg; 2052 2053 old_page = vm_normal_page(vma, address, orig_pte); 2054 if (!old_page) { 2055 /* 2056 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a 2057 * VM_PFNMAP VMA. 2058 * 2059 * We should not cow pages in a shared writeable mapping. 2060 * Just mark the pages writable as we can't do any dirty 2061 * accounting on raw pfn maps. 2062 */ 2063 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2064 (VM_WRITE|VM_SHARED)) 2065 goto reuse; 2066 goto gotten; 2067 } 2068 2069 /* 2070 * Take out anonymous pages first, anonymous shared vmas are 2071 * not dirty accountable. 2072 */ 2073 if (PageAnon(old_page) && !PageKsm(old_page)) { 2074 if (!trylock_page(old_page)) { 2075 page_cache_get(old_page); 2076 pte_unmap_unlock(page_table, ptl); 2077 lock_page(old_page); 2078 page_table = pte_offset_map_lock(mm, pmd, address, 2079 &ptl); 2080 if (!pte_same(*page_table, orig_pte)) { 2081 unlock_page(old_page); 2082 goto unlock; 2083 } 2084 page_cache_release(old_page); 2085 } 2086 if (reuse_swap_page(old_page)) { 2087 /* 2088 * The page is all ours. Move it to our anon_vma so 2089 * the rmap code will not search our parent or siblings. 2090 * Protected against the rmap code by the page lock. 2091 */ 2092 page_move_anon_rmap(old_page, vma, address); 2093 unlock_page(old_page); 2094 goto reuse; 2095 } 2096 unlock_page(old_page); 2097 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2098 (VM_WRITE|VM_SHARED))) { 2099 /* 2100 * Only catch write-faults on shared writable pages, 2101 * read-only shared pages can get COWed by 2102 * get_user_pages(.write=1, .force=1). 2103 */ 2104 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2105 int tmp; 2106 page_cache_get(old_page); 2107 pte_unmap_unlock(page_table, ptl); 2108 tmp = do_page_mkwrite(vma, old_page, address); 2109 if (unlikely(!tmp || (tmp & 2110 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 2111 page_cache_release(old_page); 2112 return tmp; 2113 } 2114 /* 2115 * Since we dropped the lock we need to revalidate 2116 * the PTE as someone else may have changed it. If 2117 * they did, we just return, as we can count on the 2118 * MMU to tell us if they didn't also make it writable. 2119 */ 2120 page_table = pte_offset_map_lock(mm, pmd, address, 2121 &ptl); 2122 if (!pte_same(*page_table, orig_pte)) { 2123 unlock_page(old_page); 2124 goto unlock; 2125 } 2126 2127 page_mkwrite = 1; 2128 } 2129 dirty_page = old_page; 2130 get_page(dirty_page); 2131 2132 reuse: 2133 /* 2134 * Clear the pages cpupid information as the existing 2135 * information potentially belongs to a now completely 2136 * unrelated process. 2137 */ 2138 if (old_page) 2139 page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1); 2140 2141 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2142 entry = pte_mkyoung(orig_pte); 2143 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2144 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2145 update_mmu_cache(vma, address, page_table); 2146 pte_unmap_unlock(page_table, ptl); 2147 ret |= VM_FAULT_WRITE; 2148 2149 if (!dirty_page) 2150 return ret; 2151 2152 /* 2153 * Yes, Virginia, this is actually required to prevent a race 2154 * with clear_page_dirty_for_io() from clearing the page dirty 2155 * bit after it clear all dirty ptes, but before a racing 2156 * do_wp_page installs a dirty pte. 2157 * 2158 * do_shared_fault is protected similarly. 2159 */ 2160 if (!page_mkwrite) { 2161 wait_on_page_locked(dirty_page); 2162 set_page_dirty_balance(dirty_page); 2163 /* file_update_time outside page_lock */ 2164 if (vma->vm_file) 2165 file_update_time(vma->vm_file); 2166 } 2167 put_page(dirty_page); 2168 if (page_mkwrite) { 2169 struct address_space *mapping = dirty_page->mapping; 2170 2171 set_page_dirty(dirty_page); 2172 unlock_page(dirty_page); 2173 page_cache_release(dirty_page); 2174 if (mapping) { 2175 /* 2176 * Some device drivers do not set page.mapping 2177 * but still dirty their pages 2178 */ 2179 balance_dirty_pages_ratelimited(mapping); 2180 } 2181 } 2182 2183 return ret; 2184 } 2185 2186 /* 2187 * Ok, we need to copy. Oh, well.. 2188 */ 2189 page_cache_get(old_page); 2190 gotten: 2191 pte_unmap_unlock(page_table, ptl); 2192 2193 if (unlikely(anon_vma_prepare(vma))) 2194 goto oom; 2195 2196 if (is_zero_pfn(pte_pfn(orig_pte))) { 2197 new_page = alloc_zeroed_user_highpage_movable(vma, address); 2198 if (!new_page) 2199 goto oom; 2200 } else { 2201 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2202 if (!new_page) 2203 goto oom; 2204 cow_user_page(new_page, old_page, address, vma); 2205 } 2206 __SetPageUptodate(new_page); 2207 2208 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)) 2209 goto oom_free_new; 2210 2211 mmun_start = address & PAGE_MASK; 2212 mmun_end = mmun_start + PAGE_SIZE; 2213 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 2214 2215 /* 2216 * Re-check the pte - we dropped the lock 2217 */ 2218 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2219 if (likely(pte_same(*page_table, orig_pte))) { 2220 if (old_page) { 2221 if (!PageAnon(old_page)) { 2222 dec_mm_counter_fast(mm, MM_FILEPAGES); 2223 inc_mm_counter_fast(mm, MM_ANONPAGES); 2224 } 2225 } else 2226 inc_mm_counter_fast(mm, MM_ANONPAGES); 2227 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2228 entry = mk_pte(new_page, vma->vm_page_prot); 2229 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2230 /* 2231 * Clear the pte entry and flush it first, before updating the 2232 * pte with the new entry. This will avoid a race condition 2233 * seen in the presence of one thread doing SMC and another 2234 * thread doing COW. 2235 */ 2236 ptep_clear_flush(vma, address, page_table); 2237 page_add_new_anon_rmap(new_page, vma, address); 2238 mem_cgroup_commit_charge(new_page, memcg, false); 2239 lru_cache_add_active_or_unevictable(new_page, vma); 2240 /* 2241 * We call the notify macro here because, when using secondary 2242 * mmu page tables (such as kvm shadow page tables), we want the 2243 * new page to be mapped directly into the secondary page table. 2244 */ 2245 set_pte_at_notify(mm, address, page_table, entry); 2246 update_mmu_cache(vma, address, page_table); 2247 if (old_page) { 2248 /* 2249 * Only after switching the pte to the new page may 2250 * we remove the mapcount here. Otherwise another 2251 * process may come and find the rmap count decremented 2252 * before the pte is switched to the new page, and 2253 * "reuse" the old page writing into it while our pte 2254 * here still points into it and can be read by other 2255 * threads. 2256 * 2257 * The critical issue is to order this 2258 * page_remove_rmap with the ptp_clear_flush above. 2259 * Those stores are ordered by (if nothing else,) 2260 * the barrier present in the atomic_add_negative 2261 * in page_remove_rmap. 2262 * 2263 * Then the TLB flush in ptep_clear_flush ensures that 2264 * no process can access the old page before the 2265 * decremented mapcount is visible. And the old page 2266 * cannot be reused until after the decremented 2267 * mapcount is visible. So transitively, TLBs to 2268 * old page will be flushed before it can be reused. 2269 */ 2270 page_remove_rmap(old_page); 2271 } 2272 2273 /* Free the old page.. */ 2274 new_page = old_page; 2275 ret |= VM_FAULT_WRITE; 2276 } else 2277 mem_cgroup_cancel_charge(new_page, memcg); 2278 2279 if (new_page) 2280 page_cache_release(new_page); 2281 unlock: 2282 pte_unmap_unlock(page_table, ptl); 2283 if (mmun_end > mmun_start) 2284 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2285 if (old_page) { 2286 /* 2287 * Don't let another task, with possibly unlocked vma, 2288 * keep the mlocked page. 2289 */ 2290 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { 2291 lock_page(old_page); /* LRU manipulation */ 2292 munlock_vma_page(old_page); 2293 unlock_page(old_page); 2294 } 2295 page_cache_release(old_page); 2296 } 2297 return ret; 2298 oom_free_new: 2299 page_cache_release(new_page); 2300 oom: 2301 if (old_page) 2302 page_cache_release(old_page); 2303 return VM_FAULT_OOM; 2304 } 2305 2306 static void unmap_mapping_range_vma(struct vm_area_struct *vma, 2307 unsigned long start_addr, unsigned long end_addr, 2308 struct zap_details *details) 2309 { 2310 zap_page_range_single(vma, start_addr, end_addr - start_addr, details); 2311 } 2312 2313 static inline void unmap_mapping_range_tree(struct rb_root *root, 2314 struct zap_details *details) 2315 { 2316 struct vm_area_struct *vma; 2317 pgoff_t vba, vea, zba, zea; 2318 2319 vma_interval_tree_foreach(vma, root, 2320 details->first_index, details->last_index) { 2321 2322 vba = vma->vm_pgoff; 2323 vea = vba + vma_pages(vma) - 1; 2324 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2325 zba = details->first_index; 2326 if (zba < vba) 2327 zba = vba; 2328 zea = details->last_index; 2329 if (zea > vea) 2330 zea = vea; 2331 2332 unmap_mapping_range_vma(vma, 2333 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2334 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2335 details); 2336 } 2337 } 2338 2339 static inline void unmap_mapping_range_list(struct list_head *head, 2340 struct zap_details *details) 2341 { 2342 struct vm_area_struct *vma; 2343 2344 /* 2345 * In nonlinear VMAs there is no correspondence between virtual address 2346 * offset and file offset. So we must perform an exhaustive search 2347 * across *all* the pages in each nonlinear VMA, not just the pages 2348 * whose virtual address lies outside the file truncation point. 2349 */ 2350 list_for_each_entry(vma, head, shared.nonlinear) { 2351 details->nonlinear_vma = vma; 2352 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details); 2353 } 2354 } 2355 2356 /** 2357 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2358 * @mapping: the address space containing mmaps to be unmapped. 2359 * @holebegin: byte in first page to unmap, relative to the start of 2360 * the underlying file. This will be rounded down to a PAGE_SIZE 2361 * boundary. Note that this is different from truncate_pagecache(), which 2362 * must keep the partial page. In contrast, we must get rid of 2363 * partial pages. 2364 * @holelen: size of prospective hole in bytes. This will be rounded 2365 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2366 * end of the file. 2367 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2368 * but 0 when invalidating pagecache, don't throw away private data. 2369 */ 2370 void unmap_mapping_range(struct address_space *mapping, 2371 loff_t const holebegin, loff_t const holelen, int even_cows) 2372 { 2373 struct zap_details details; 2374 pgoff_t hba = holebegin >> PAGE_SHIFT; 2375 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2376 2377 /* Check for overflow. */ 2378 if (sizeof(holelen) > sizeof(hlen)) { 2379 long long holeend = 2380 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2381 if (holeend & ~(long long)ULONG_MAX) 2382 hlen = ULONG_MAX - hba + 1; 2383 } 2384 2385 details.check_mapping = even_cows? NULL: mapping; 2386 details.nonlinear_vma = NULL; 2387 details.first_index = hba; 2388 details.last_index = hba + hlen - 1; 2389 if (details.last_index < details.first_index) 2390 details.last_index = ULONG_MAX; 2391 2392 2393 mutex_lock(&mapping->i_mmap_mutex); 2394 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap))) 2395 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2396 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 2397 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 2398 mutex_unlock(&mapping->i_mmap_mutex); 2399 } 2400 EXPORT_SYMBOL(unmap_mapping_range); 2401 2402 /* 2403 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2404 * but allow concurrent faults), and pte mapped but not yet locked. 2405 * We return with pte unmapped and unlocked. 2406 * 2407 * We return with the mmap_sem locked or unlocked in the same cases 2408 * as does filemap_fault(). 2409 */ 2410 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2411 unsigned long address, pte_t *page_table, pmd_t *pmd, 2412 unsigned int flags, pte_t orig_pte) 2413 { 2414 spinlock_t *ptl; 2415 struct page *page, *swapcache; 2416 struct mem_cgroup *memcg; 2417 swp_entry_t entry; 2418 pte_t pte; 2419 int locked; 2420 int exclusive = 0; 2421 int ret = 0; 2422 2423 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2424 goto out; 2425 2426 entry = pte_to_swp_entry(orig_pte); 2427 if (unlikely(non_swap_entry(entry))) { 2428 if (is_migration_entry(entry)) { 2429 migration_entry_wait(mm, pmd, address); 2430 } else if (is_hwpoison_entry(entry)) { 2431 ret = VM_FAULT_HWPOISON; 2432 } else { 2433 print_bad_pte(vma, address, orig_pte, NULL); 2434 ret = VM_FAULT_SIGBUS; 2435 } 2436 goto out; 2437 } 2438 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2439 page = lookup_swap_cache(entry); 2440 if (!page) { 2441 page = swapin_readahead(entry, 2442 GFP_HIGHUSER_MOVABLE, vma, address); 2443 if (!page) { 2444 /* 2445 * Back out if somebody else faulted in this pte 2446 * while we released the pte lock. 2447 */ 2448 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2449 if (likely(pte_same(*page_table, orig_pte))) 2450 ret = VM_FAULT_OOM; 2451 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2452 goto unlock; 2453 } 2454 2455 /* Had to read the page from swap area: Major fault */ 2456 ret = VM_FAULT_MAJOR; 2457 count_vm_event(PGMAJFAULT); 2458 mem_cgroup_count_vm_event(mm, PGMAJFAULT); 2459 } else if (PageHWPoison(page)) { 2460 /* 2461 * hwpoisoned dirty swapcache pages are kept for killing 2462 * owner processes (which may be unknown at hwpoison time) 2463 */ 2464 ret = VM_FAULT_HWPOISON; 2465 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2466 swapcache = page; 2467 goto out_release; 2468 } 2469 2470 swapcache = page; 2471 locked = lock_page_or_retry(page, mm, flags); 2472 2473 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2474 if (!locked) { 2475 ret |= VM_FAULT_RETRY; 2476 goto out_release; 2477 } 2478 2479 /* 2480 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 2481 * release the swapcache from under us. The page pin, and pte_same 2482 * test below, are not enough to exclude that. Even if it is still 2483 * swapcache, we need to check that the page's swap has not changed. 2484 */ 2485 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) 2486 goto out_page; 2487 2488 page = ksm_might_need_to_copy(page, vma, address); 2489 if (unlikely(!page)) { 2490 ret = VM_FAULT_OOM; 2491 page = swapcache; 2492 goto out_page; 2493 } 2494 2495 if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) { 2496 ret = VM_FAULT_OOM; 2497 goto out_page; 2498 } 2499 2500 /* 2501 * Back out if somebody else already faulted in this pte. 2502 */ 2503 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2504 if (unlikely(!pte_same(*page_table, orig_pte))) 2505 goto out_nomap; 2506 2507 if (unlikely(!PageUptodate(page))) { 2508 ret = VM_FAULT_SIGBUS; 2509 goto out_nomap; 2510 } 2511 2512 /* 2513 * The page isn't present yet, go ahead with the fault. 2514 * 2515 * Be careful about the sequence of operations here. 2516 * To get its accounting right, reuse_swap_page() must be called 2517 * while the page is counted on swap but not yet in mapcount i.e. 2518 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2519 * must be called after the swap_free(), or it will never succeed. 2520 */ 2521 2522 inc_mm_counter_fast(mm, MM_ANONPAGES); 2523 dec_mm_counter_fast(mm, MM_SWAPENTS); 2524 pte = mk_pte(page, vma->vm_page_prot); 2525 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 2526 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2527 flags &= ~FAULT_FLAG_WRITE; 2528 ret |= VM_FAULT_WRITE; 2529 exclusive = 1; 2530 } 2531 flush_icache_page(vma, page); 2532 if (pte_swp_soft_dirty(orig_pte)) 2533 pte = pte_mksoft_dirty(pte); 2534 set_pte_at(mm, address, page_table, pte); 2535 if (page == swapcache) { 2536 do_page_add_anon_rmap(page, vma, address, exclusive); 2537 mem_cgroup_commit_charge(page, memcg, true); 2538 } else { /* ksm created a completely new copy */ 2539 page_add_new_anon_rmap(page, vma, address); 2540 mem_cgroup_commit_charge(page, memcg, false); 2541 lru_cache_add_active_or_unevictable(page, vma); 2542 } 2543 2544 swap_free(entry); 2545 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 2546 try_to_free_swap(page); 2547 unlock_page(page); 2548 if (page != swapcache) { 2549 /* 2550 * Hold the lock to avoid the swap entry to be reused 2551 * until we take the PT lock for the pte_same() check 2552 * (to avoid false positives from pte_same). For 2553 * further safety release the lock after the swap_free 2554 * so that the swap count won't change under a 2555 * parallel locked swapcache. 2556 */ 2557 unlock_page(swapcache); 2558 page_cache_release(swapcache); 2559 } 2560 2561 if (flags & FAULT_FLAG_WRITE) { 2562 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 2563 if (ret & VM_FAULT_ERROR) 2564 ret &= VM_FAULT_ERROR; 2565 goto out; 2566 } 2567 2568 /* No need to invalidate - it was non-present before */ 2569 update_mmu_cache(vma, address, page_table); 2570 unlock: 2571 pte_unmap_unlock(page_table, ptl); 2572 out: 2573 return ret; 2574 out_nomap: 2575 mem_cgroup_cancel_charge(page, memcg); 2576 pte_unmap_unlock(page_table, ptl); 2577 out_page: 2578 unlock_page(page); 2579 out_release: 2580 page_cache_release(page); 2581 if (page != swapcache) { 2582 unlock_page(swapcache); 2583 page_cache_release(swapcache); 2584 } 2585 return ret; 2586 } 2587 2588 /* 2589 * This is like a special single-page "expand_{down|up}wards()", 2590 * except we must first make sure that 'address{-|+}PAGE_SIZE' 2591 * doesn't hit another vma. 2592 */ 2593 static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) 2594 { 2595 address &= PAGE_MASK; 2596 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { 2597 struct vm_area_struct *prev = vma->vm_prev; 2598 2599 /* 2600 * Is there a mapping abutting this one below? 2601 * 2602 * That's only ok if it's the same stack mapping 2603 * that has gotten split.. 2604 */ 2605 if (prev && prev->vm_end == address) 2606 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; 2607 2608 expand_downwards(vma, address - PAGE_SIZE); 2609 } 2610 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { 2611 struct vm_area_struct *next = vma->vm_next; 2612 2613 /* As VM_GROWSDOWN but s/below/above/ */ 2614 if (next && next->vm_start == address + PAGE_SIZE) 2615 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; 2616 2617 expand_upwards(vma, address + PAGE_SIZE); 2618 } 2619 return 0; 2620 } 2621 2622 /* 2623 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2624 * but allow concurrent faults), and pte mapped but not yet locked. 2625 * We return with mmap_sem still held, but pte unmapped and unlocked. 2626 */ 2627 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2628 unsigned long address, pte_t *page_table, pmd_t *pmd, 2629 unsigned int flags) 2630 { 2631 struct mem_cgroup *memcg; 2632 struct page *page; 2633 spinlock_t *ptl; 2634 pte_t entry; 2635 2636 pte_unmap(page_table); 2637 2638 /* Check if we need to add a guard page to the stack */ 2639 if (check_stack_guard_page(vma, address) < 0) 2640 return VM_FAULT_SIGBUS; 2641 2642 /* Use the zero-page for reads */ 2643 if (!(flags & FAULT_FLAG_WRITE)) { 2644 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), 2645 vma->vm_page_prot)); 2646 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2647 if (!pte_none(*page_table)) 2648 goto unlock; 2649 goto setpte; 2650 } 2651 2652 /* Allocate our own private page. */ 2653 if (unlikely(anon_vma_prepare(vma))) 2654 goto oom; 2655 page = alloc_zeroed_user_highpage_movable(vma, address); 2656 if (!page) 2657 goto oom; 2658 /* 2659 * The memory barrier inside __SetPageUptodate makes sure that 2660 * preceeding stores to the page contents become visible before 2661 * the set_pte_at() write. 2662 */ 2663 __SetPageUptodate(page); 2664 2665 if (mem_cgroup_try_charge(page, mm, GFP_KERNEL, &memcg)) 2666 goto oom_free_page; 2667 2668 entry = mk_pte(page, vma->vm_page_prot); 2669 if (vma->vm_flags & VM_WRITE) 2670 entry = pte_mkwrite(pte_mkdirty(entry)); 2671 2672 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2673 if (!pte_none(*page_table)) 2674 goto release; 2675 2676 inc_mm_counter_fast(mm, MM_ANONPAGES); 2677 page_add_new_anon_rmap(page, vma, address); 2678 mem_cgroup_commit_charge(page, memcg, false); 2679 lru_cache_add_active_or_unevictable(page, vma); 2680 setpte: 2681 set_pte_at(mm, address, page_table, entry); 2682 2683 /* No need to invalidate - it was non-present before */ 2684 update_mmu_cache(vma, address, page_table); 2685 unlock: 2686 pte_unmap_unlock(page_table, ptl); 2687 return 0; 2688 release: 2689 mem_cgroup_cancel_charge(page, memcg); 2690 page_cache_release(page); 2691 goto unlock; 2692 oom_free_page: 2693 page_cache_release(page); 2694 oom: 2695 return VM_FAULT_OOM; 2696 } 2697 2698 /* 2699 * The mmap_sem must have been held on entry, and may have been 2700 * released depending on flags and vma->vm_ops->fault() return value. 2701 * See filemap_fault() and __lock_page_retry(). 2702 */ 2703 static int __do_fault(struct vm_area_struct *vma, unsigned long address, 2704 pgoff_t pgoff, unsigned int flags, struct page **page) 2705 { 2706 struct vm_fault vmf; 2707 int ret; 2708 2709 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2710 vmf.pgoff = pgoff; 2711 vmf.flags = flags; 2712 vmf.page = NULL; 2713 2714 ret = vma->vm_ops->fault(vma, &vmf); 2715 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2716 return ret; 2717 2718 if (unlikely(PageHWPoison(vmf.page))) { 2719 if (ret & VM_FAULT_LOCKED) 2720 unlock_page(vmf.page); 2721 page_cache_release(vmf.page); 2722 return VM_FAULT_HWPOISON; 2723 } 2724 2725 if (unlikely(!(ret & VM_FAULT_LOCKED))) 2726 lock_page(vmf.page); 2727 else 2728 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page); 2729 2730 *page = vmf.page; 2731 return ret; 2732 } 2733 2734 /** 2735 * do_set_pte - setup new PTE entry for given page and add reverse page mapping. 2736 * 2737 * @vma: virtual memory area 2738 * @address: user virtual address 2739 * @page: page to map 2740 * @pte: pointer to target page table entry 2741 * @write: true, if new entry is writable 2742 * @anon: true, if it's anonymous page 2743 * 2744 * Caller must hold page table lock relevant for @pte. 2745 * 2746 * Target users are page handler itself and implementations of 2747 * vm_ops->map_pages. 2748 */ 2749 void do_set_pte(struct vm_area_struct *vma, unsigned long address, 2750 struct page *page, pte_t *pte, bool write, bool anon) 2751 { 2752 pte_t entry; 2753 2754 flush_icache_page(vma, page); 2755 entry = mk_pte(page, vma->vm_page_prot); 2756 if (write) 2757 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2758 else if (pte_file(*pte) && pte_file_soft_dirty(*pte)) 2759 entry = pte_mksoft_dirty(entry); 2760 if (anon) { 2761 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES); 2762 page_add_new_anon_rmap(page, vma, address); 2763 } else { 2764 inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES); 2765 page_add_file_rmap(page); 2766 } 2767 set_pte_at(vma->vm_mm, address, pte, entry); 2768 2769 /* no need to invalidate: a not-present page won't be cached */ 2770 update_mmu_cache(vma, address, pte); 2771 } 2772 2773 static unsigned long fault_around_bytes __read_mostly = 2774 rounddown_pow_of_two(65536); 2775 2776 #ifdef CONFIG_DEBUG_FS 2777 static int fault_around_bytes_get(void *data, u64 *val) 2778 { 2779 *val = fault_around_bytes; 2780 return 0; 2781 } 2782 2783 /* 2784 * fault_around_pages() and fault_around_mask() expects fault_around_bytes 2785 * rounded down to nearest page order. It's what do_fault_around() expects to 2786 * see. 2787 */ 2788 static int fault_around_bytes_set(void *data, u64 val) 2789 { 2790 if (val / PAGE_SIZE > PTRS_PER_PTE) 2791 return -EINVAL; 2792 if (val > PAGE_SIZE) 2793 fault_around_bytes = rounddown_pow_of_two(val); 2794 else 2795 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */ 2796 return 0; 2797 } 2798 DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops, 2799 fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); 2800 2801 static int __init fault_around_debugfs(void) 2802 { 2803 void *ret; 2804 2805 ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL, 2806 &fault_around_bytes_fops); 2807 if (!ret) 2808 pr_warn("Failed to create fault_around_bytes in debugfs"); 2809 return 0; 2810 } 2811 late_initcall(fault_around_debugfs); 2812 #endif 2813 2814 /* 2815 * do_fault_around() tries to map few pages around the fault address. The hope 2816 * is that the pages will be needed soon and this will lower the number of 2817 * faults to handle. 2818 * 2819 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's 2820 * not ready to be mapped: not up-to-date, locked, etc. 2821 * 2822 * This function is called with the page table lock taken. In the split ptlock 2823 * case the page table lock only protects only those entries which belong to 2824 * the page table corresponding to the fault address. 2825 * 2826 * This function doesn't cross the VMA boundaries, in order to call map_pages() 2827 * only once. 2828 * 2829 * fault_around_pages() defines how many pages we'll try to map. 2830 * do_fault_around() expects it to return a power of two less than or equal to 2831 * PTRS_PER_PTE. 2832 * 2833 * The virtual address of the area that we map is naturally aligned to the 2834 * fault_around_pages() value (and therefore to page order). This way it's 2835 * easier to guarantee that we don't cross page table boundaries. 2836 */ 2837 static void do_fault_around(struct vm_area_struct *vma, unsigned long address, 2838 pte_t *pte, pgoff_t pgoff, unsigned int flags) 2839 { 2840 unsigned long start_addr, nr_pages, mask; 2841 pgoff_t max_pgoff; 2842 struct vm_fault vmf; 2843 int off; 2844 2845 nr_pages = ACCESS_ONCE(fault_around_bytes) >> PAGE_SHIFT; 2846 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK; 2847 2848 start_addr = max(address & mask, vma->vm_start); 2849 off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); 2850 pte -= off; 2851 pgoff -= off; 2852 2853 /* 2854 * max_pgoff is either end of page table or end of vma 2855 * or fault_around_pages() from pgoff, depending what is nearest. 2856 */ 2857 max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) + 2858 PTRS_PER_PTE - 1; 2859 max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1, 2860 pgoff + nr_pages - 1); 2861 2862 /* Check if it makes any sense to call ->map_pages */ 2863 while (!pte_none(*pte)) { 2864 if (++pgoff > max_pgoff) 2865 return; 2866 start_addr += PAGE_SIZE; 2867 if (start_addr >= vma->vm_end) 2868 return; 2869 pte++; 2870 } 2871 2872 vmf.virtual_address = (void __user *) start_addr; 2873 vmf.pte = pte; 2874 vmf.pgoff = pgoff; 2875 vmf.max_pgoff = max_pgoff; 2876 vmf.flags = flags; 2877 vma->vm_ops->map_pages(vma, &vmf); 2878 } 2879 2880 static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2881 unsigned long address, pmd_t *pmd, 2882 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2883 { 2884 struct page *fault_page; 2885 spinlock_t *ptl; 2886 pte_t *pte; 2887 int ret = 0; 2888 2889 /* 2890 * Let's call ->map_pages() first and use ->fault() as fallback 2891 * if page by the offset is not ready to be mapped (cold cache or 2892 * something). 2893 */ 2894 if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) && 2895 fault_around_bytes >> PAGE_SHIFT > 1) { 2896 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 2897 do_fault_around(vma, address, pte, pgoff, flags); 2898 if (!pte_same(*pte, orig_pte)) 2899 goto unlock_out; 2900 pte_unmap_unlock(pte, ptl); 2901 } 2902 2903 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 2904 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2905 return ret; 2906 2907 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 2908 if (unlikely(!pte_same(*pte, orig_pte))) { 2909 pte_unmap_unlock(pte, ptl); 2910 unlock_page(fault_page); 2911 page_cache_release(fault_page); 2912 return ret; 2913 } 2914 do_set_pte(vma, address, fault_page, pte, false, false); 2915 unlock_page(fault_page); 2916 unlock_out: 2917 pte_unmap_unlock(pte, ptl); 2918 return ret; 2919 } 2920 2921 static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2922 unsigned long address, pmd_t *pmd, 2923 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2924 { 2925 struct page *fault_page, *new_page; 2926 struct mem_cgroup *memcg; 2927 spinlock_t *ptl; 2928 pte_t *pte; 2929 int ret; 2930 2931 if (unlikely(anon_vma_prepare(vma))) 2932 return VM_FAULT_OOM; 2933 2934 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2935 if (!new_page) 2936 return VM_FAULT_OOM; 2937 2938 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg)) { 2939 page_cache_release(new_page); 2940 return VM_FAULT_OOM; 2941 } 2942 2943 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 2944 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2945 goto uncharge_out; 2946 2947 copy_user_highpage(new_page, fault_page, address, vma); 2948 __SetPageUptodate(new_page); 2949 2950 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 2951 if (unlikely(!pte_same(*pte, orig_pte))) { 2952 pte_unmap_unlock(pte, ptl); 2953 unlock_page(fault_page); 2954 page_cache_release(fault_page); 2955 goto uncharge_out; 2956 } 2957 do_set_pte(vma, address, new_page, pte, true, true); 2958 mem_cgroup_commit_charge(new_page, memcg, false); 2959 lru_cache_add_active_or_unevictable(new_page, vma); 2960 pte_unmap_unlock(pte, ptl); 2961 unlock_page(fault_page); 2962 page_cache_release(fault_page); 2963 return ret; 2964 uncharge_out: 2965 mem_cgroup_cancel_charge(new_page, memcg); 2966 page_cache_release(new_page); 2967 return ret; 2968 } 2969 2970 static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2971 unsigned long address, pmd_t *pmd, 2972 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2973 { 2974 struct page *fault_page; 2975 struct address_space *mapping; 2976 spinlock_t *ptl; 2977 pte_t *pte; 2978 int dirtied = 0; 2979 int ret, tmp; 2980 2981 ret = __do_fault(vma, address, pgoff, flags, &fault_page); 2982 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY))) 2983 return ret; 2984 2985 /* 2986 * Check if the backing address space wants to know that the page is 2987 * about to become writable 2988 */ 2989 if (vma->vm_ops->page_mkwrite) { 2990 unlock_page(fault_page); 2991 tmp = do_page_mkwrite(vma, fault_page, address); 2992 if (unlikely(!tmp || 2993 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { 2994 page_cache_release(fault_page); 2995 return tmp; 2996 } 2997 } 2998 2999 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 3000 if (unlikely(!pte_same(*pte, orig_pte))) { 3001 pte_unmap_unlock(pte, ptl); 3002 unlock_page(fault_page); 3003 page_cache_release(fault_page); 3004 return ret; 3005 } 3006 do_set_pte(vma, address, fault_page, pte, true, false); 3007 pte_unmap_unlock(pte, ptl); 3008 3009 if (set_page_dirty(fault_page)) 3010 dirtied = 1; 3011 mapping = fault_page->mapping; 3012 unlock_page(fault_page); 3013 if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) { 3014 /* 3015 * Some device drivers do not set page.mapping but still 3016 * dirty their pages 3017 */ 3018 balance_dirty_pages_ratelimited(mapping); 3019 } 3020 3021 /* file_update_time outside page_lock */ 3022 if (vma->vm_file && !vma->vm_ops->page_mkwrite) 3023 file_update_time(vma->vm_file); 3024 3025 return ret; 3026 } 3027 3028 /* 3029 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3030 * but allow concurrent faults). 3031 * The mmap_sem may have been released depending on flags and our 3032 * return value. See filemap_fault() and __lock_page_or_retry(). 3033 */ 3034 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3035 unsigned long address, pte_t *page_table, pmd_t *pmd, 3036 unsigned int flags, pte_t orig_pte) 3037 { 3038 pgoff_t pgoff = (((address & PAGE_MASK) 3039 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 3040 3041 pte_unmap(page_table); 3042 if (!(flags & FAULT_FLAG_WRITE)) 3043 return do_read_fault(mm, vma, address, pmd, pgoff, flags, 3044 orig_pte); 3045 if (!(vma->vm_flags & VM_SHARED)) 3046 return do_cow_fault(mm, vma, address, pmd, pgoff, flags, 3047 orig_pte); 3048 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3049 } 3050 3051 /* 3052 * Fault of a previously existing named mapping. Repopulate the pte 3053 * from the encoded file_pte if possible. This enables swappable 3054 * nonlinear vmas. 3055 * 3056 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3057 * but allow concurrent faults), and pte mapped but not yet locked. 3058 * We return with pte unmapped and unlocked. 3059 * The mmap_sem may have been released depending on flags and our 3060 * return value. See filemap_fault() and __lock_page_or_retry(). 3061 */ 3062 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3063 unsigned long address, pte_t *page_table, pmd_t *pmd, 3064 unsigned int flags, pte_t orig_pte) 3065 { 3066 pgoff_t pgoff; 3067 3068 flags |= FAULT_FLAG_NONLINEAR; 3069 3070 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3071 return 0; 3072 3073 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 3074 /* 3075 * Page table corrupted: show pte and kill process. 3076 */ 3077 print_bad_pte(vma, address, orig_pte, NULL); 3078 return VM_FAULT_SIGBUS; 3079 } 3080 3081 pgoff = pte_to_pgoff(orig_pte); 3082 if (!(flags & FAULT_FLAG_WRITE)) 3083 return do_read_fault(mm, vma, address, pmd, pgoff, flags, 3084 orig_pte); 3085 if (!(vma->vm_flags & VM_SHARED)) 3086 return do_cow_fault(mm, vma, address, pmd, pgoff, flags, 3087 orig_pte); 3088 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3089 } 3090 3091 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma, 3092 unsigned long addr, int page_nid, 3093 int *flags) 3094 { 3095 get_page(page); 3096 3097 count_vm_numa_event(NUMA_HINT_FAULTS); 3098 if (page_nid == numa_node_id()) { 3099 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL); 3100 *flags |= TNF_FAULT_LOCAL; 3101 } 3102 3103 return mpol_misplaced(page, vma, addr); 3104 } 3105 3106 static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma, 3107 unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd) 3108 { 3109 struct page *page = NULL; 3110 spinlock_t *ptl; 3111 int page_nid = -1; 3112 int last_cpupid; 3113 int target_nid; 3114 bool migrated = false; 3115 int flags = 0; 3116 3117 /* 3118 * The "pte" at this point cannot be used safely without 3119 * validation through pte_unmap_same(). It's of NUMA type but 3120 * the pfn may be screwed if the read is non atomic. 3121 * 3122 * ptep_modify_prot_start is not called as this is clearing 3123 * the _PAGE_NUMA bit and it is not really expected that there 3124 * would be concurrent hardware modifications to the PTE. 3125 */ 3126 ptl = pte_lockptr(mm, pmd); 3127 spin_lock(ptl); 3128 if (unlikely(!pte_same(*ptep, pte))) { 3129 pte_unmap_unlock(ptep, ptl); 3130 goto out; 3131 } 3132 3133 pte = pte_mknonnuma(pte); 3134 set_pte_at(mm, addr, ptep, pte); 3135 update_mmu_cache(vma, addr, ptep); 3136 3137 page = vm_normal_page(vma, addr, pte); 3138 if (!page) { 3139 pte_unmap_unlock(ptep, ptl); 3140 return 0; 3141 } 3142 BUG_ON(is_zero_pfn(page_to_pfn(page))); 3143 3144 /* 3145 * Avoid grouping on DSO/COW pages in specific and RO pages 3146 * in general, RO pages shouldn't hurt as much anyway since 3147 * they can be in shared cache state. 3148 */ 3149 if (!pte_write(pte)) 3150 flags |= TNF_NO_GROUP; 3151 3152 /* 3153 * Flag if the page is shared between multiple address spaces. This 3154 * is later used when determining whether to group tasks together 3155 */ 3156 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED)) 3157 flags |= TNF_SHARED; 3158 3159 last_cpupid = page_cpupid_last(page); 3160 page_nid = page_to_nid(page); 3161 target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags); 3162 pte_unmap_unlock(ptep, ptl); 3163 if (target_nid == -1) { 3164 put_page(page); 3165 goto out; 3166 } 3167 3168 /* Migrate to the requested node */ 3169 migrated = migrate_misplaced_page(page, vma, target_nid); 3170 if (migrated) { 3171 page_nid = target_nid; 3172 flags |= TNF_MIGRATED; 3173 } 3174 3175 out: 3176 if (page_nid != -1) 3177 task_numa_fault(last_cpupid, page_nid, 1, flags); 3178 return 0; 3179 } 3180 3181 /* 3182 * These routines also need to handle stuff like marking pages dirty 3183 * and/or accessed for architectures that don't do it in hardware (most 3184 * RISC architectures). The early dirtying is also good on the i386. 3185 * 3186 * There is also a hook called "update_mmu_cache()" that architectures 3187 * with external mmu caches can use to update those (ie the Sparc or 3188 * PowerPC hashed page tables that act as extended TLBs). 3189 * 3190 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3191 * but allow concurrent faults), and pte mapped but not yet locked. 3192 * We return with pte unmapped and unlocked. 3193 * 3194 * The mmap_sem may have been released depending on flags and our 3195 * return value. See filemap_fault() and __lock_page_or_retry(). 3196 */ 3197 static int handle_pte_fault(struct mm_struct *mm, 3198 struct vm_area_struct *vma, unsigned long address, 3199 pte_t *pte, pmd_t *pmd, unsigned int flags) 3200 { 3201 pte_t entry; 3202 spinlock_t *ptl; 3203 3204 entry = ACCESS_ONCE(*pte); 3205 if (!pte_present(entry)) { 3206 if (pte_none(entry)) { 3207 if (vma->vm_ops) { 3208 if (likely(vma->vm_ops->fault)) 3209 return do_linear_fault(mm, vma, address, 3210 pte, pmd, flags, entry); 3211 } 3212 return do_anonymous_page(mm, vma, address, 3213 pte, pmd, flags); 3214 } 3215 if (pte_file(entry)) 3216 return do_nonlinear_fault(mm, vma, address, 3217 pte, pmd, flags, entry); 3218 return do_swap_page(mm, vma, address, 3219 pte, pmd, flags, entry); 3220 } 3221 3222 if (pte_numa(entry)) 3223 return do_numa_page(mm, vma, address, entry, pte, pmd); 3224 3225 ptl = pte_lockptr(mm, pmd); 3226 spin_lock(ptl); 3227 if (unlikely(!pte_same(*pte, entry))) 3228 goto unlock; 3229 if (flags & FAULT_FLAG_WRITE) { 3230 if (!pte_write(entry)) 3231 return do_wp_page(mm, vma, address, 3232 pte, pmd, ptl, entry); 3233 entry = pte_mkdirty(entry); 3234 } 3235 entry = pte_mkyoung(entry); 3236 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 3237 update_mmu_cache(vma, address, pte); 3238 } else { 3239 /* 3240 * This is needed only for protection faults but the arch code 3241 * is not yet telling us if this is a protection fault or not. 3242 * This still avoids useless tlb flushes for .text page faults 3243 * with threads. 3244 */ 3245 if (flags & FAULT_FLAG_WRITE) 3246 flush_tlb_fix_spurious_fault(vma, address); 3247 } 3248 unlock: 3249 pte_unmap_unlock(pte, ptl); 3250 return 0; 3251 } 3252 3253 /* 3254 * By the time we get here, we already hold the mm semaphore 3255 * 3256 * The mmap_sem may have been released depending on flags and our 3257 * return value. See filemap_fault() and __lock_page_or_retry(). 3258 */ 3259 static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3260 unsigned long address, unsigned int flags) 3261 { 3262 pgd_t *pgd; 3263 pud_t *pud; 3264 pmd_t *pmd; 3265 pte_t *pte; 3266 3267 if (unlikely(is_vm_hugetlb_page(vma))) 3268 return hugetlb_fault(mm, vma, address, flags); 3269 3270 pgd = pgd_offset(mm, address); 3271 pud = pud_alloc(mm, pgd, address); 3272 if (!pud) 3273 return VM_FAULT_OOM; 3274 pmd = pmd_alloc(mm, pud, address); 3275 if (!pmd) 3276 return VM_FAULT_OOM; 3277 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { 3278 int ret = VM_FAULT_FALLBACK; 3279 if (!vma->vm_ops) 3280 ret = do_huge_pmd_anonymous_page(mm, vma, address, 3281 pmd, flags); 3282 if (!(ret & VM_FAULT_FALLBACK)) 3283 return ret; 3284 } else { 3285 pmd_t orig_pmd = *pmd; 3286 int ret; 3287 3288 barrier(); 3289 if (pmd_trans_huge(orig_pmd)) { 3290 unsigned int dirty = flags & FAULT_FLAG_WRITE; 3291 3292 /* 3293 * If the pmd is splitting, return and retry the 3294 * the fault. Alternative: wait until the split 3295 * is done, and goto retry. 3296 */ 3297 if (pmd_trans_splitting(orig_pmd)) 3298 return 0; 3299 3300 if (pmd_numa(orig_pmd)) 3301 return do_huge_pmd_numa_page(mm, vma, address, 3302 orig_pmd, pmd); 3303 3304 if (dirty && !pmd_write(orig_pmd)) { 3305 ret = do_huge_pmd_wp_page(mm, vma, address, pmd, 3306 orig_pmd); 3307 if (!(ret & VM_FAULT_FALLBACK)) 3308 return ret; 3309 } else { 3310 huge_pmd_set_accessed(mm, vma, address, pmd, 3311 orig_pmd, dirty); 3312 return 0; 3313 } 3314 } 3315 } 3316 3317 /* 3318 * Use __pte_alloc instead of pte_alloc_map, because we can't 3319 * run pte_offset_map on the pmd, if an huge pmd could 3320 * materialize from under us from a different thread. 3321 */ 3322 if (unlikely(pmd_none(*pmd)) && 3323 unlikely(__pte_alloc(mm, vma, pmd, address))) 3324 return VM_FAULT_OOM; 3325 /* if an huge pmd materialized from under us just retry later */ 3326 if (unlikely(pmd_trans_huge(*pmd))) 3327 return 0; 3328 /* 3329 * A regular pmd is established and it can't morph into a huge pmd 3330 * from under us anymore at this point because we hold the mmap_sem 3331 * read mode and khugepaged takes it in write mode. So now it's 3332 * safe to run pte_offset_map(). 3333 */ 3334 pte = pte_offset_map(pmd, address); 3335 3336 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 3337 } 3338 3339 /* 3340 * By the time we get here, we already hold the mm semaphore 3341 * 3342 * The mmap_sem may have been released depending on flags and our 3343 * return value. See filemap_fault() and __lock_page_or_retry(). 3344 */ 3345 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3346 unsigned long address, unsigned int flags) 3347 { 3348 int ret; 3349 3350 __set_current_state(TASK_RUNNING); 3351 3352 count_vm_event(PGFAULT); 3353 mem_cgroup_count_vm_event(mm, PGFAULT); 3354 3355 /* do counter updates before entering really critical section. */ 3356 check_sync_rss_stat(current); 3357 3358 /* 3359 * Enable the memcg OOM handling for faults triggered in user 3360 * space. Kernel faults are handled more gracefully. 3361 */ 3362 if (flags & FAULT_FLAG_USER) 3363 mem_cgroup_oom_enable(); 3364 3365 ret = __handle_mm_fault(mm, vma, address, flags); 3366 3367 if (flags & FAULT_FLAG_USER) { 3368 mem_cgroup_oom_disable(); 3369 /* 3370 * The task may have entered a memcg OOM situation but 3371 * if the allocation error was handled gracefully (no 3372 * VM_FAULT_OOM), there is no need to kill anything. 3373 * Just clean up the OOM state peacefully. 3374 */ 3375 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM)) 3376 mem_cgroup_oom_synchronize(false); 3377 } 3378 3379 return ret; 3380 } 3381 3382 #ifndef __PAGETABLE_PUD_FOLDED 3383 /* 3384 * Allocate page upper directory. 3385 * We've already handled the fast-path in-line. 3386 */ 3387 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3388 { 3389 pud_t *new = pud_alloc_one(mm, address); 3390 if (!new) 3391 return -ENOMEM; 3392 3393 smp_wmb(); /* See comment in __pte_alloc */ 3394 3395 spin_lock(&mm->page_table_lock); 3396 if (pgd_present(*pgd)) /* Another has populated it */ 3397 pud_free(mm, new); 3398 else 3399 pgd_populate(mm, pgd, new); 3400 spin_unlock(&mm->page_table_lock); 3401 return 0; 3402 } 3403 #endif /* __PAGETABLE_PUD_FOLDED */ 3404 3405 #ifndef __PAGETABLE_PMD_FOLDED 3406 /* 3407 * Allocate page middle directory. 3408 * We've already handled the fast-path in-line. 3409 */ 3410 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 3411 { 3412 pmd_t *new = pmd_alloc_one(mm, address); 3413 if (!new) 3414 return -ENOMEM; 3415 3416 smp_wmb(); /* See comment in __pte_alloc */ 3417 3418 spin_lock(&mm->page_table_lock); 3419 #ifndef __ARCH_HAS_4LEVEL_HACK 3420 if (pud_present(*pud)) /* Another has populated it */ 3421 pmd_free(mm, new); 3422 else 3423 pud_populate(mm, pud, new); 3424 #else 3425 if (pgd_present(*pud)) /* Another has populated it */ 3426 pmd_free(mm, new); 3427 else 3428 pgd_populate(mm, pud, new); 3429 #endif /* __ARCH_HAS_4LEVEL_HACK */ 3430 spin_unlock(&mm->page_table_lock); 3431 return 0; 3432 } 3433 #endif /* __PAGETABLE_PMD_FOLDED */ 3434 3435 static int __follow_pte(struct mm_struct *mm, unsigned long address, 3436 pte_t **ptepp, spinlock_t **ptlp) 3437 { 3438 pgd_t *pgd; 3439 pud_t *pud; 3440 pmd_t *pmd; 3441 pte_t *ptep; 3442 3443 pgd = pgd_offset(mm, address); 3444 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 3445 goto out; 3446 3447 pud = pud_offset(pgd, address); 3448 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 3449 goto out; 3450 3451 pmd = pmd_offset(pud, address); 3452 VM_BUG_ON(pmd_trans_huge(*pmd)); 3453 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 3454 goto out; 3455 3456 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 3457 if (pmd_huge(*pmd)) 3458 goto out; 3459 3460 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 3461 if (!ptep) 3462 goto out; 3463 if (!pte_present(*ptep)) 3464 goto unlock; 3465 *ptepp = ptep; 3466 return 0; 3467 unlock: 3468 pte_unmap_unlock(ptep, *ptlp); 3469 out: 3470 return -EINVAL; 3471 } 3472 3473 static inline int follow_pte(struct mm_struct *mm, unsigned long address, 3474 pte_t **ptepp, spinlock_t **ptlp) 3475 { 3476 int res; 3477 3478 /* (void) is needed to make gcc happy */ 3479 (void) __cond_lock(*ptlp, 3480 !(res = __follow_pte(mm, address, ptepp, ptlp))); 3481 return res; 3482 } 3483 3484 /** 3485 * follow_pfn - look up PFN at a user virtual address 3486 * @vma: memory mapping 3487 * @address: user virtual address 3488 * @pfn: location to store found PFN 3489 * 3490 * Only IO mappings and raw PFN mappings are allowed. 3491 * 3492 * Returns zero and the pfn at @pfn on success, -ve otherwise. 3493 */ 3494 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 3495 unsigned long *pfn) 3496 { 3497 int ret = -EINVAL; 3498 spinlock_t *ptl; 3499 pte_t *ptep; 3500 3501 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3502 return ret; 3503 3504 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 3505 if (ret) 3506 return ret; 3507 *pfn = pte_pfn(*ptep); 3508 pte_unmap_unlock(ptep, ptl); 3509 return 0; 3510 } 3511 EXPORT_SYMBOL(follow_pfn); 3512 3513 #ifdef CONFIG_HAVE_IOREMAP_PROT 3514 int follow_phys(struct vm_area_struct *vma, 3515 unsigned long address, unsigned int flags, 3516 unsigned long *prot, resource_size_t *phys) 3517 { 3518 int ret = -EINVAL; 3519 pte_t *ptep, pte; 3520 spinlock_t *ptl; 3521 3522 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3523 goto out; 3524 3525 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 3526 goto out; 3527 pte = *ptep; 3528 3529 if ((flags & FOLL_WRITE) && !pte_write(pte)) 3530 goto unlock; 3531 3532 *prot = pgprot_val(pte_pgprot(pte)); 3533 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 3534 3535 ret = 0; 3536 unlock: 3537 pte_unmap_unlock(ptep, ptl); 3538 out: 3539 return ret; 3540 } 3541 3542 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 3543 void *buf, int len, int write) 3544 { 3545 resource_size_t phys_addr; 3546 unsigned long prot = 0; 3547 void __iomem *maddr; 3548 int offset = addr & (PAGE_SIZE-1); 3549 3550 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 3551 return -EINVAL; 3552 3553 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 3554 if (write) 3555 memcpy_toio(maddr + offset, buf, len); 3556 else 3557 memcpy_fromio(buf, maddr + offset, len); 3558 iounmap(maddr); 3559 3560 return len; 3561 } 3562 EXPORT_SYMBOL_GPL(generic_access_phys); 3563 #endif 3564 3565 /* 3566 * Access another process' address space as given in mm. If non-NULL, use the 3567 * given task for page fault accounting. 3568 */ 3569 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 3570 unsigned long addr, void *buf, int len, int write) 3571 { 3572 struct vm_area_struct *vma; 3573 void *old_buf = buf; 3574 3575 down_read(&mm->mmap_sem); 3576 /* ignore errors, just check how much was successfully transferred */ 3577 while (len) { 3578 int bytes, ret, offset; 3579 void *maddr; 3580 struct page *page = NULL; 3581 3582 ret = get_user_pages(tsk, mm, addr, 1, 3583 write, 1, &page, &vma); 3584 if (ret <= 0) { 3585 #ifndef CONFIG_HAVE_IOREMAP_PROT 3586 break; 3587 #else 3588 /* 3589 * Check if this is a VM_IO | VM_PFNMAP VMA, which 3590 * we can access using slightly different code. 3591 */ 3592 vma = find_vma(mm, addr); 3593 if (!vma || vma->vm_start > addr) 3594 break; 3595 if (vma->vm_ops && vma->vm_ops->access) 3596 ret = vma->vm_ops->access(vma, addr, buf, 3597 len, write); 3598 if (ret <= 0) 3599 break; 3600 bytes = ret; 3601 #endif 3602 } else { 3603 bytes = len; 3604 offset = addr & (PAGE_SIZE-1); 3605 if (bytes > PAGE_SIZE-offset) 3606 bytes = PAGE_SIZE-offset; 3607 3608 maddr = kmap(page); 3609 if (write) { 3610 copy_to_user_page(vma, page, addr, 3611 maddr + offset, buf, bytes); 3612 set_page_dirty_lock(page); 3613 } else { 3614 copy_from_user_page(vma, page, addr, 3615 buf, maddr + offset, bytes); 3616 } 3617 kunmap(page); 3618 page_cache_release(page); 3619 } 3620 len -= bytes; 3621 buf += bytes; 3622 addr += bytes; 3623 } 3624 up_read(&mm->mmap_sem); 3625 3626 return buf - old_buf; 3627 } 3628 3629 /** 3630 * access_remote_vm - access another process' address space 3631 * @mm: the mm_struct of the target address space 3632 * @addr: start address to access 3633 * @buf: source or destination buffer 3634 * @len: number of bytes to transfer 3635 * @write: whether the access is a write 3636 * 3637 * The caller must hold a reference on @mm. 3638 */ 3639 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 3640 void *buf, int len, int write) 3641 { 3642 return __access_remote_vm(NULL, mm, addr, buf, len, write); 3643 } 3644 3645 /* 3646 * Access another process' address space. 3647 * Source/target buffer must be kernel space, 3648 * Do not walk the page table directly, use get_user_pages 3649 */ 3650 int access_process_vm(struct task_struct *tsk, unsigned long addr, 3651 void *buf, int len, int write) 3652 { 3653 struct mm_struct *mm; 3654 int ret; 3655 3656 mm = get_task_mm(tsk); 3657 if (!mm) 3658 return 0; 3659 3660 ret = __access_remote_vm(tsk, mm, addr, buf, len, write); 3661 mmput(mm); 3662 3663 return ret; 3664 } 3665 3666 /* 3667 * Print the name of a VMA. 3668 */ 3669 void print_vma_addr(char *prefix, unsigned long ip) 3670 { 3671 struct mm_struct *mm = current->mm; 3672 struct vm_area_struct *vma; 3673 3674 /* 3675 * Do not print if we are in atomic 3676 * contexts (in exception stacks, etc.): 3677 */ 3678 if (preempt_count()) 3679 return; 3680 3681 down_read(&mm->mmap_sem); 3682 vma = find_vma(mm, ip); 3683 if (vma && vma->vm_file) { 3684 struct file *f = vma->vm_file; 3685 char *buf = (char *)__get_free_page(GFP_KERNEL); 3686 if (buf) { 3687 char *p; 3688 3689 p = d_path(&f->f_path, buf, PAGE_SIZE); 3690 if (IS_ERR(p)) 3691 p = "?"; 3692 printk("%s%s[%lx+%lx]", prefix, kbasename(p), 3693 vma->vm_start, 3694 vma->vm_end - vma->vm_start); 3695 free_page((unsigned long)buf); 3696 } 3697 } 3698 up_read(&mm->mmap_sem); 3699 } 3700 3701 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP) 3702 void might_fault(void) 3703 { 3704 /* 3705 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 3706 * holding the mmap_sem, this is safe because kernel memory doesn't 3707 * get paged out, therefore we'll never actually fault, and the 3708 * below annotations will generate false positives. 3709 */ 3710 if (segment_eq(get_fs(), KERNEL_DS)) 3711 return; 3712 3713 /* 3714 * it would be nicer only to annotate paths which are not under 3715 * pagefault_disable, however that requires a larger audit and 3716 * providing helpers like get_user_atomic. 3717 */ 3718 if (in_atomic()) 3719 return; 3720 3721 __might_sleep(__FILE__, __LINE__, 0); 3722 3723 if (current->mm) 3724 might_lock_read(¤t->mm->mmap_sem); 3725 } 3726 EXPORT_SYMBOL(might_fault); 3727 #endif 3728 3729 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 3730 static void clear_gigantic_page(struct page *page, 3731 unsigned long addr, 3732 unsigned int pages_per_huge_page) 3733 { 3734 int i; 3735 struct page *p = page; 3736 3737 might_sleep(); 3738 for (i = 0; i < pages_per_huge_page; 3739 i++, p = mem_map_next(p, page, i)) { 3740 cond_resched(); 3741 clear_user_highpage(p, addr + i * PAGE_SIZE); 3742 } 3743 } 3744 void clear_huge_page(struct page *page, 3745 unsigned long addr, unsigned int pages_per_huge_page) 3746 { 3747 int i; 3748 3749 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 3750 clear_gigantic_page(page, addr, pages_per_huge_page); 3751 return; 3752 } 3753 3754 might_sleep(); 3755 for (i = 0; i < pages_per_huge_page; i++) { 3756 cond_resched(); 3757 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 3758 } 3759 } 3760 3761 static void copy_user_gigantic_page(struct page *dst, struct page *src, 3762 unsigned long addr, 3763 struct vm_area_struct *vma, 3764 unsigned int pages_per_huge_page) 3765 { 3766 int i; 3767 struct page *dst_base = dst; 3768 struct page *src_base = src; 3769 3770 for (i = 0; i < pages_per_huge_page; ) { 3771 cond_resched(); 3772 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 3773 3774 i++; 3775 dst = mem_map_next(dst, dst_base, i); 3776 src = mem_map_next(src, src_base, i); 3777 } 3778 } 3779 3780 void copy_user_huge_page(struct page *dst, struct page *src, 3781 unsigned long addr, struct vm_area_struct *vma, 3782 unsigned int pages_per_huge_page) 3783 { 3784 int i; 3785 3786 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 3787 copy_user_gigantic_page(dst, src, addr, vma, 3788 pages_per_huge_page); 3789 return; 3790 } 3791 3792 might_sleep(); 3793 for (i = 0; i < pages_per_huge_page; i++) { 3794 cond_resched(); 3795 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 3796 } 3797 } 3798 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 3799 3800 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS 3801 3802 static struct kmem_cache *page_ptl_cachep; 3803 3804 void __init ptlock_cache_init(void) 3805 { 3806 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0, 3807 SLAB_PANIC, NULL); 3808 } 3809 3810 bool ptlock_alloc(struct page *page) 3811 { 3812 spinlock_t *ptl; 3813 3814 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); 3815 if (!ptl) 3816 return false; 3817 page->ptl = ptl; 3818 return true; 3819 } 3820 3821 void ptlock_free(struct page *page) 3822 { 3823 kmem_cache_free(page_ptl_cachep, page->ptl); 3824 } 3825 #endif 3826