memory.c revision cc03638df20acbec5d0d0d9e07234aadde9e698d
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/module.h> 51#include <linux/delayacct.h> 52#include <linux/init.h> 53#include <linux/writeback.h> 54#include <linux/memcontrol.h> 55#include <linux/mmu_notifier.h> 56#include <linux/kallsyms.h> 57#include <linux/swapops.h> 58#include <linux/elf.h> 59#include <linux/gfp.h> 60 61#include <asm/io.h> 62#include <asm/pgalloc.h> 63#include <asm/uaccess.h> 64#include <asm/tlb.h> 65#include <asm/tlbflush.h> 66#include <asm/pgtable.h> 67 68#include "internal.h" 69 70#ifndef CONFIG_NEED_MULTIPLE_NODES 71/* use the per-pgdat data instead for discontigmem - mbligh */ 72unsigned long max_mapnr; 73struct page *mem_map; 74 75EXPORT_SYMBOL(max_mapnr); 76EXPORT_SYMBOL(mem_map); 77#endif 78 79unsigned long num_physpages; 80/* 81 * A number of key systems in x86 including ioremap() rely on the assumption 82 * that high_memory defines the upper bound on direct map memory, then end 83 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 84 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 85 * and ZONE_HIGHMEM. 86 */ 87void * high_memory; 88 89EXPORT_SYMBOL(num_physpages); 90EXPORT_SYMBOL(high_memory); 91 92/* 93 * Randomize the address space (stacks, mmaps, brk, etc.). 94 * 95 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 96 * as ancient (libc5 based) binaries can segfault. ) 97 */ 98int randomize_va_space __read_mostly = 99#ifdef CONFIG_COMPAT_BRK 100 1; 101#else 102 2; 103#endif 104 105static int __init disable_randmaps(char *s) 106{ 107 randomize_va_space = 0; 108 return 1; 109} 110__setup("norandmaps", disable_randmaps); 111 112unsigned long zero_pfn __read_mostly; 113unsigned long highest_memmap_pfn __read_mostly; 114 115/* 116 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 117 */ 118static int __init init_zero_pfn(void) 119{ 120 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 121 return 0; 122} 123core_initcall(init_zero_pfn); 124 125 126#if defined(SPLIT_RSS_COUNTING) 127 128static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm) 129{ 130 int i; 131 132 for (i = 0; i < NR_MM_COUNTERS; i++) { 133 if (task->rss_stat.count[i]) { 134 add_mm_counter(mm, i, task->rss_stat.count[i]); 135 task->rss_stat.count[i] = 0; 136 } 137 } 138 task->rss_stat.events = 0; 139} 140 141static void add_mm_counter_fast(struct mm_struct *mm, int member, int val) 142{ 143 struct task_struct *task = current; 144 145 if (likely(task->mm == mm)) 146 task->rss_stat.count[member] += val; 147 else 148 add_mm_counter(mm, member, val); 149} 150#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1) 151#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1) 152 153/* sync counter once per 64 page faults */ 154#define TASK_RSS_EVENTS_THRESH (64) 155static void check_sync_rss_stat(struct task_struct *task) 156{ 157 if (unlikely(task != current)) 158 return; 159 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH)) 160 __sync_task_rss_stat(task, task->mm); 161} 162 163unsigned long get_mm_counter(struct mm_struct *mm, int member) 164{ 165 long val = 0; 166 167 /* 168 * Don't use task->mm here...for avoiding to use task_get_mm().. 169 * The caller must guarantee task->mm is not invalid. 170 */ 171 val = atomic_long_read(&mm->rss_stat.count[member]); 172 /* 173 * counter is updated in asynchronous manner and may go to minus. 174 * But it's never be expected number for users. 175 */ 176 if (val < 0) 177 return 0; 178 return (unsigned long)val; 179} 180 181void sync_mm_rss(struct task_struct *task, struct mm_struct *mm) 182{ 183 __sync_task_rss_stat(task, mm); 184} 185#else 186 187#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member) 188#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member) 189 190static void check_sync_rss_stat(struct task_struct *task) 191{ 192} 193 194#endif 195 196/* 197 * If a p?d_bad entry is found while walking page tables, report 198 * the error, before resetting entry to p?d_none. Usually (but 199 * very seldom) called out from the p?d_none_or_clear_bad macros. 200 */ 201 202void pgd_clear_bad(pgd_t *pgd) 203{ 204 pgd_ERROR(*pgd); 205 pgd_clear(pgd); 206} 207 208void pud_clear_bad(pud_t *pud) 209{ 210 pud_ERROR(*pud); 211 pud_clear(pud); 212} 213 214void pmd_clear_bad(pmd_t *pmd) 215{ 216 pmd_ERROR(*pmd); 217 pmd_clear(pmd); 218} 219 220/* 221 * Note: this doesn't free the actual pages themselves. That 222 * has been handled earlier when unmapping all the memory regions. 223 */ 224static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 225 unsigned long addr) 226{ 227 pgtable_t token = pmd_pgtable(*pmd); 228 pmd_clear(pmd); 229 pte_free_tlb(tlb, token, addr); 230 tlb->mm->nr_ptes--; 231} 232 233static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 234 unsigned long addr, unsigned long end, 235 unsigned long floor, unsigned long ceiling) 236{ 237 pmd_t *pmd; 238 unsigned long next; 239 unsigned long start; 240 241 start = addr; 242 pmd = pmd_offset(pud, addr); 243 do { 244 next = pmd_addr_end(addr, end); 245 if (pmd_none_or_clear_bad(pmd)) 246 continue; 247 free_pte_range(tlb, pmd, addr); 248 } while (pmd++, addr = next, addr != end); 249 250 start &= PUD_MASK; 251 if (start < floor) 252 return; 253 if (ceiling) { 254 ceiling &= PUD_MASK; 255 if (!ceiling) 256 return; 257 } 258 if (end - 1 > ceiling - 1) 259 return; 260 261 pmd = pmd_offset(pud, start); 262 pud_clear(pud); 263 pmd_free_tlb(tlb, pmd, start); 264} 265 266static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 267 unsigned long addr, unsigned long end, 268 unsigned long floor, unsigned long ceiling) 269{ 270 pud_t *pud; 271 unsigned long next; 272 unsigned long start; 273 274 start = addr; 275 pud = pud_offset(pgd, addr); 276 do { 277 next = pud_addr_end(addr, end); 278 if (pud_none_or_clear_bad(pud)) 279 continue; 280 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 281 } while (pud++, addr = next, addr != end); 282 283 start &= PGDIR_MASK; 284 if (start < floor) 285 return; 286 if (ceiling) { 287 ceiling &= PGDIR_MASK; 288 if (!ceiling) 289 return; 290 } 291 if (end - 1 > ceiling - 1) 292 return; 293 294 pud = pud_offset(pgd, start); 295 pgd_clear(pgd); 296 pud_free_tlb(tlb, pud, start); 297} 298 299/* 300 * This function frees user-level page tables of a process. 301 * 302 * Must be called with pagetable lock held. 303 */ 304void free_pgd_range(struct mmu_gather *tlb, 305 unsigned long addr, unsigned long end, 306 unsigned long floor, unsigned long ceiling) 307{ 308 pgd_t *pgd; 309 unsigned long next; 310 311 /* 312 * The next few lines have given us lots of grief... 313 * 314 * Why are we testing PMD* at this top level? Because often 315 * there will be no work to do at all, and we'd prefer not to 316 * go all the way down to the bottom just to discover that. 317 * 318 * Why all these "- 1"s? Because 0 represents both the bottom 319 * of the address space and the top of it (using -1 for the 320 * top wouldn't help much: the masks would do the wrong thing). 321 * The rule is that addr 0 and floor 0 refer to the bottom of 322 * the address space, but end 0 and ceiling 0 refer to the top 323 * Comparisons need to use "end - 1" and "ceiling - 1" (though 324 * that end 0 case should be mythical). 325 * 326 * Wherever addr is brought up or ceiling brought down, we must 327 * be careful to reject "the opposite 0" before it confuses the 328 * subsequent tests. But what about where end is brought down 329 * by PMD_SIZE below? no, end can't go down to 0 there. 330 * 331 * Whereas we round start (addr) and ceiling down, by different 332 * masks at different levels, in order to test whether a table 333 * now has no other vmas using it, so can be freed, we don't 334 * bother to round floor or end up - the tests don't need that. 335 */ 336 337 addr &= PMD_MASK; 338 if (addr < floor) { 339 addr += PMD_SIZE; 340 if (!addr) 341 return; 342 } 343 if (ceiling) { 344 ceiling &= PMD_MASK; 345 if (!ceiling) 346 return; 347 } 348 if (end - 1 > ceiling - 1) 349 end -= PMD_SIZE; 350 if (addr > end - 1) 351 return; 352 353 pgd = pgd_offset(tlb->mm, addr); 354 do { 355 next = pgd_addr_end(addr, end); 356 if (pgd_none_or_clear_bad(pgd)) 357 continue; 358 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 359 } while (pgd++, addr = next, addr != end); 360} 361 362void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 363 unsigned long floor, unsigned long ceiling) 364{ 365 while (vma) { 366 struct vm_area_struct *next = vma->vm_next; 367 unsigned long addr = vma->vm_start; 368 369 /* 370 * Hide vma from rmap and truncate_pagecache before freeing 371 * pgtables 372 */ 373 unlink_anon_vmas(vma); 374 unlink_file_vma(vma); 375 376 if (is_vm_hugetlb_page(vma)) { 377 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 378 floor, next? next->vm_start: ceiling); 379 } else { 380 /* 381 * Optimization: gather nearby vmas into one call down 382 */ 383 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 384 && !is_vm_hugetlb_page(next)) { 385 vma = next; 386 next = vma->vm_next; 387 unlink_anon_vmas(vma); 388 unlink_file_vma(vma); 389 } 390 free_pgd_range(tlb, addr, vma->vm_end, 391 floor, next? next->vm_start: ceiling); 392 } 393 vma = next; 394 } 395} 396 397int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma, 398 pmd_t *pmd, unsigned long address) 399{ 400 pgtable_t new = pte_alloc_one(mm, address); 401 int wait_split_huge_page; 402 if (!new) 403 return -ENOMEM; 404 405 /* 406 * Ensure all pte setup (eg. pte page lock and page clearing) are 407 * visible before the pte is made visible to other CPUs by being 408 * put into page tables. 409 * 410 * The other side of the story is the pointer chasing in the page 411 * table walking code (when walking the page table without locking; 412 * ie. most of the time). Fortunately, these data accesses consist 413 * of a chain of data-dependent loads, meaning most CPUs (alpha 414 * being the notable exception) will already guarantee loads are 415 * seen in-order. See the alpha page table accessors for the 416 * smp_read_barrier_depends() barriers in page table walking code. 417 */ 418 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 419 420 spin_lock(&mm->page_table_lock); 421 wait_split_huge_page = 0; 422 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 423 mm->nr_ptes++; 424 pmd_populate(mm, pmd, new); 425 new = NULL; 426 } else if (unlikely(pmd_trans_splitting(*pmd))) 427 wait_split_huge_page = 1; 428 spin_unlock(&mm->page_table_lock); 429 if (new) 430 pte_free(mm, new); 431 if (wait_split_huge_page) 432 wait_split_huge_page(vma->anon_vma, pmd); 433 return 0; 434} 435 436int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 437{ 438 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 439 if (!new) 440 return -ENOMEM; 441 442 smp_wmb(); /* See comment in __pte_alloc */ 443 444 spin_lock(&init_mm.page_table_lock); 445 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */ 446 pmd_populate_kernel(&init_mm, pmd, new); 447 new = NULL; 448 } else 449 VM_BUG_ON(pmd_trans_splitting(*pmd)); 450 spin_unlock(&init_mm.page_table_lock); 451 if (new) 452 pte_free_kernel(&init_mm, new); 453 return 0; 454} 455 456static inline void init_rss_vec(int *rss) 457{ 458 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS); 459} 460 461static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss) 462{ 463 int i; 464 465 if (current->mm == mm) 466 sync_mm_rss(current, mm); 467 for (i = 0; i < NR_MM_COUNTERS; i++) 468 if (rss[i]) 469 add_mm_counter(mm, i, rss[i]); 470} 471 472/* 473 * This function is called to print an error when a bad pte 474 * is found. For example, we might have a PFN-mapped pte in 475 * a region that doesn't allow it. 476 * 477 * The calling function must still handle the error. 478 */ 479static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 480 pte_t pte, struct page *page) 481{ 482 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 483 pud_t *pud = pud_offset(pgd, addr); 484 pmd_t *pmd = pmd_offset(pud, addr); 485 struct address_space *mapping; 486 pgoff_t index; 487 static unsigned long resume; 488 static unsigned long nr_shown; 489 static unsigned long nr_unshown; 490 491 /* 492 * Allow a burst of 60 reports, then keep quiet for that minute; 493 * or allow a steady drip of one report per second. 494 */ 495 if (nr_shown == 60) { 496 if (time_before(jiffies, resume)) { 497 nr_unshown++; 498 return; 499 } 500 if (nr_unshown) { 501 printk(KERN_ALERT 502 "BUG: Bad page map: %lu messages suppressed\n", 503 nr_unshown); 504 nr_unshown = 0; 505 } 506 nr_shown = 0; 507 } 508 if (nr_shown++ == 0) 509 resume = jiffies + 60 * HZ; 510 511 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 512 index = linear_page_index(vma, addr); 513 514 printk(KERN_ALERT 515 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 516 current->comm, 517 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 518 if (page) 519 dump_page(page); 520 printk(KERN_ALERT 521 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 522 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 523 /* 524 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 525 */ 526 if (vma->vm_ops) 527 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n", 528 (unsigned long)vma->vm_ops->fault); 529 if (vma->vm_file && vma->vm_file->f_op) 530 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n", 531 (unsigned long)vma->vm_file->f_op->mmap); 532 dump_stack(); 533 add_taint(TAINT_BAD_PAGE); 534} 535 536static inline int is_cow_mapping(unsigned int flags) 537{ 538 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 539} 540 541#ifndef is_zero_pfn 542static inline int is_zero_pfn(unsigned long pfn) 543{ 544 return pfn == zero_pfn; 545} 546#endif 547 548#ifndef my_zero_pfn 549static inline unsigned long my_zero_pfn(unsigned long addr) 550{ 551 return zero_pfn; 552} 553#endif 554 555/* 556 * vm_normal_page -- This function gets the "struct page" associated with a pte. 557 * 558 * "Special" mappings do not wish to be associated with a "struct page" (either 559 * it doesn't exist, or it exists but they don't want to touch it). In this 560 * case, NULL is returned here. "Normal" mappings do have a struct page. 561 * 562 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 563 * pte bit, in which case this function is trivial. Secondly, an architecture 564 * may not have a spare pte bit, which requires a more complicated scheme, 565 * described below. 566 * 567 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 568 * special mapping (even if there are underlying and valid "struct pages"). 569 * COWed pages of a VM_PFNMAP are always normal. 570 * 571 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 572 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 573 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 574 * mapping will always honor the rule 575 * 576 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 577 * 578 * And for normal mappings this is false. 579 * 580 * This restricts such mappings to be a linear translation from virtual address 581 * to pfn. To get around this restriction, we allow arbitrary mappings so long 582 * as the vma is not a COW mapping; in that case, we know that all ptes are 583 * special (because none can have been COWed). 584 * 585 * 586 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 587 * 588 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 589 * page" backing, however the difference is that _all_ pages with a struct 590 * page (that is, those where pfn_valid is true) are refcounted and considered 591 * normal pages by the VM. The disadvantage is that pages are refcounted 592 * (which can be slower and simply not an option for some PFNMAP users). The 593 * advantage is that we don't have to follow the strict linearity rule of 594 * PFNMAP mappings in order to support COWable mappings. 595 * 596 */ 597#ifdef __HAVE_ARCH_PTE_SPECIAL 598# define HAVE_PTE_SPECIAL 1 599#else 600# define HAVE_PTE_SPECIAL 0 601#endif 602struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 603 pte_t pte) 604{ 605 unsigned long pfn = pte_pfn(pte); 606 607 if (HAVE_PTE_SPECIAL) { 608 if (likely(!pte_special(pte))) 609 goto check_pfn; 610 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 611 return NULL; 612 if (!is_zero_pfn(pfn)) 613 print_bad_pte(vma, addr, pte, NULL); 614 return NULL; 615 } 616 617 /* !HAVE_PTE_SPECIAL case follows: */ 618 619 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 620 if (vma->vm_flags & VM_MIXEDMAP) { 621 if (!pfn_valid(pfn)) 622 return NULL; 623 goto out; 624 } else { 625 unsigned long off; 626 off = (addr - vma->vm_start) >> PAGE_SHIFT; 627 if (pfn == vma->vm_pgoff + off) 628 return NULL; 629 if (!is_cow_mapping(vma->vm_flags)) 630 return NULL; 631 } 632 } 633 634 if (is_zero_pfn(pfn)) 635 return NULL; 636check_pfn: 637 if (unlikely(pfn > highest_memmap_pfn)) { 638 print_bad_pte(vma, addr, pte, NULL); 639 return NULL; 640 } 641 642 /* 643 * NOTE! We still have PageReserved() pages in the page tables. 644 * eg. VDSO mappings can cause them to exist. 645 */ 646out: 647 return pfn_to_page(pfn); 648} 649 650/* 651 * copy one vm_area from one task to the other. Assumes the page tables 652 * already present in the new task to be cleared in the whole range 653 * covered by this vma. 654 */ 655 656static inline unsigned long 657copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 658 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 659 unsigned long addr, int *rss) 660{ 661 unsigned long vm_flags = vma->vm_flags; 662 pte_t pte = *src_pte; 663 struct page *page; 664 665 /* pte contains position in swap or file, so copy. */ 666 if (unlikely(!pte_present(pte))) { 667 if (!pte_file(pte)) { 668 swp_entry_t entry = pte_to_swp_entry(pte); 669 670 if (swap_duplicate(entry) < 0) 671 return entry.val; 672 673 /* make sure dst_mm is on swapoff's mmlist. */ 674 if (unlikely(list_empty(&dst_mm->mmlist))) { 675 spin_lock(&mmlist_lock); 676 if (list_empty(&dst_mm->mmlist)) 677 list_add(&dst_mm->mmlist, 678 &src_mm->mmlist); 679 spin_unlock(&mmlist_lock); 680 } 681 if (likely(!non_swap_entry(entry))) 682 rss[MM_SWAPENTS]++; 683 else if (is_write_migration_entry(entry) && 684 is_cow_mapping(vm_flags)) { 685 /* 686 * COW mappings require pages in both parent 687 * and child to be set to read. 688 */ 689 make_migration_entry_read(&entry); 690 pte = swp_entry_to_pte(entry); 691 set_pte_at(src_mm, addr, src_pte, pte); 692 } 693 } 694 goto out_set_pte; 695 } 696 697 /* 698 * If it's a COW mapping, write protect it both 699 * in the parent and the child 700 */ 701 if (is_cow_mapping(vm_flags)) { 702 ptep_set_wrprotect(src_mm, addr, src_pte); 703 pte = pte_wrprotect(pte); 704 } 705 706 /* 707 * If it's a shared mapping, mark it clean in 708 * the child 709 */ 710 if (vm_flags & VM_SHARED) 711 pte = pte_mkclean(pte); 712 pte = pte_mkold(pte); 713 714 page = vm_normal_page(vma, addr, pte); 715 if (page) { 716 get_page(page); 717 page_dup_rmap(page); 718 if (PageAnon(page)) 719 rss[MM_ANONPAGES]++; 720 else 721 rss[MM_FILEPAGES]++; 722 } 723 724out_set_pte: 725 set_pte_at(dst_mm, addr, dst_pte, pte); 726 return 0; 727} 728 729int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 730 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 731 unsigned long addr, unsigned long end) 732{ 733 pte_t *orig_src_pte, *orig_dst_pte; 734 pte_t *src_pte, *dst_pte; 735 spinlock_t *src_ptl, *dst_ptl; 736 int progress = 0; 737 int rss[NR_MM_COUNTERS]; 738 swp_entry_t entry = (swp_entry_t){0}; 739 740again: 741 init_rss_vec(rss); 742 743 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 744 if (!dst_pte) 745 return -ENOMEM; 746 src_pte = pte_offset_map(src_pmd, addr); 747 src_ptl = pte_lockptr(src_mm, src_pmd); 748 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 749 orig_src_pte = src_pte; 750 orig_dst_pte = dst_pte; 751 arch_enter_lazy_mmu_mode(); 752 753 do { 754 /* 755 * We are holding two locks at this point - either of them 756 * could generate latencies in another task on another CPU. 757 */ 758 if (progress >= 32) { 759 progress = 0; 760 if (need_resched() || 761 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 762 break; 763 } 764 if (pte_none(*src_pte)) { 765 progress++; 766 continue; 767 } 768 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 769 vma, addr, rss); 770 if (entry.val) 771 break; 772 progress += 8; 773 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 774 775 arch_leave_lazy_mmu_mode(); 776 spin_unlock(src_ptl); 777 pte_unmap(orig_src_pte); 778 add_mm_rss_vec(dst_mm, rss); 779 pte_unmap_unlock(orig_dst_pte, dst_ptl); 780 cond_resched(); 781 782 if (entry.val) { 783 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 784 return -ENOMEM; 785 progress = 0; 786 } 787 if (addr != end) 788 goto again; 789 return 0; 790} 791 792static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 793 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 794 unsigned long addr, unsigned long end) 795{ 796 pmd_t *src_pmd, *dst_pmd; 797 unsigned long next; 798 799 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 800 if (!dst_pmd) 801 return -ENOMEM; 802 src_pmd = pmd_offset(src_pud, addr); 803 do { 804 next = pmd_addr_end(addr, end); 805 if (pmd_trans_huge(*src_pmd)) { 806 int err; 807 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE); 808 err = copy_huge_pmd(dst_mm, src_mm, 809 dst_pmd, src_pmd, addr, vma); 810 if (err == -ENOMEM) 811 return -ENOMEM; 812 if (!err) 813 continue; 814 /* fall through */ 815 } 816 if (pmd_none_or_clear_bad(src_pmd)) 817 continue; 818 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 819 vma, addr, next)) 820 return -ENOMEM; 821 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 822 return 0; 823} 824 825static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 826 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 827 unsigned long addr, unsigned long end) 828{ 829 pud_t *src_pud, *dst_pud; 830 unsigned long next; 831 832 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 833 if (!dst_pud) 834 return -ENOMEM; 835 src_pud = pud_offset(src_pgd, addr); 836 do { 837 next = pud_addr_end(addr, end); 838 if (pud_none_or_clear_bad(src_pud)) 839 continue; 840 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 841 vma, addr, next)) 842 return -ENOMEM; 843 } while (dst_pud++, src_pud++, addr = next, addr != end); 844 return 0; 845} 846 847int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 848 struct vm_area_struct *vma) 849{ 850 pgd_t *src_pgd, *dst_pgd; 851 unsigned long next; 852 unsigned long addr = vma->vm_start; 853 unsigned long end = vma->vm_end; 854 int ret; 855 856 /* 857 * Don't copy ptes where a page fault will fill them correctly. 858 * Fork becomes much lighter when there are big shared or private 859 * readonly mappings. The tradeoff is that copy_page_range is more 860 * efficient than faulting. 861 */ 862 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 863 if (!vma->anon_vma) 864 return 0; 865 } 866 867 if (is_vm_hugetlb_page(vma)) 868 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 869 870 if (unlikely(is_pfn_mapping(vma))) { 871 /* 872 * We do not free on error cases below as remove_vma 873 * gets called on error from higher level routine 874 */ 875 ret = track_pfn_vma_copy(vma); 876 if (ret) 877 return ret; 878 } 879 880 /* 881 * We need to invalidate the secondary MMU mappings only when 882 * there could be a permission downgrade on the ptes of the 883 * parent mm. And a permission downgrade will only happen if 884 * is_cow_mapping() returns true. 885 */ 886 if (is_cow_mapping(vma->vm_flags)) 887 mmu_notifier_invalidate_range_start(src_mm, addr, end); 888 889 ret = 0; 890 dst_pgd = pgd_offset(dst_mm, addr); 891 src_pgd = pgd_offset(src_mm, addr); 892 do { 893 next = pgd_addr_end(addr, end); 894 if (pgd_none_or_clear_bad(src_pgd)) 895 continue; 896 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 897 vma, addr, next))) { 898 ret = -ENOMEM; 899 break; 900 } 901 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 902 903 if (is_cow_mapping(vma->vm_flags)) 904 mmu_notifier_invalidate_range_end(src_mm, 905 vma->vm_start, end); 906 return ret; 907} 908 909static unsigned long zap_pte_range(struct mmu_gather *tlb, 910 struct vm_area_struct *vma, pmd_t *pmd, 911 unsigned long addr, unsigned long end, 912 long *zap_work, struct zap_details *details) 913{ 914 struct mm_struct *mm = tlb->mm; 915 pte_t *pte; 916 spinlock_t *ptl; 917 int rss[NR_MM_COUNTERS]; 918 919 init_rss_vec(rss); 920 921 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 922 arch_enter_lazy_mmu_mode(); 923 do { 924 pte_t ptent = *pte; 925 if (pte_none(ptent)) { 926 (*zap_work)--; 927 continue; 928 } 929 930 (*zap_work) -= PAGE_SIZE; 931 932 if (pte_present(ptent)) { 933 struct page *page; 934 935 page = vm_normal_page(vma, addr, ptent); 936 if (unlikely(details) && page) { 937 /* 938 * unmap_shared_mapping_pages() wants to 939 * invalidate cache without truncating: 940 * unmap shared but keep private pages. 941 */ 942 if (details->check_mapping && 943 details->check_mapping != page->mapping) 944 continue; 945 /* 946 * Each page->index must be checked when 947 * invalidating or truncating nonlinear. 948 */ 949 if (details->nonlinear_vma && 950 (page->index < details->first_index || 951 page->index > details->last_index)) 952 continue; 953 } 954 ptent = ptep_get_and_clear_full(mm, addr, pte, 955 tlb->fullmm); 956 tlb_remove_tlb_entry(tlb, pte, addr); 957 if (unlikely(!page)) 958 continue; 959 if (unlikely(details) && details->nonlinear_vma 960 && linear_page_index(details->nonlinear_vma, 961 addr) != page->index) 962 set_pte_at(mm, addr, pte, 963 pgoff_to_pte(page->index)); 964 if (PageAnon(page)) 965 rss[MM_ANONPAGES]--; 966 else { 967 if (pte_dirty(ptent)) 968 set_page_dirty(page); 969 if (pte_young(ptent) && 970 likely(!VM_SequentialReadHint(vma))) 971 mark_page_accessed(page); 972 rss[MM_FILEPAGES]--; 973 } 974 page_remove_rmap(page); 975 if (unlikely(page_mapcount(page) < 0)) 976 print_bad_pte(vma, addr, ptent, page); 977 tlb_remove_page(tlb, page); 978 continue; 979 } 980 /* 981 * If details->check_mapping, we leave swap entries; 982 * if details->nonlinear_vma, we leave file entries. 983 */ 984 if (unlikely(details)) 985 continue; 986 if (pte_file(ptent)) { 987 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 988 print_bad_pte(vma, addr, ptent, NULL); 989 } else { 990 swp_entry_t entry = pte_to_swp_entry(ptent); 991 992 if (!non_swap_entry(entry)) 993 rss[MM_SWAPENTS]--; 994 if (unlikely(!free_swap_and_cache(entry))) 995 print_bad_pte(vma, addr, ptent, NULL); 996 } 997 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 998 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 999 1000 add_mm_rss_vec(mm, rss); 1001 arch_leave_lazy_mmu_mode(); 1002 pte_unmap_unlock(pte - 1, ptl); 1003 1004 return addr; 1005} 1006 1007static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 1008 struct vm_area_struct *vma, pud_t *pud, 1009 unsigned long addr, unsigned long end, 1010 long *zap_work, struct zap_details *details) 1011{ 1012 pmd_t *pmd; 1013 unsigned long next; 1014 1015 pmd = pmd_offset(pud, addr); 1016 do { 1017 next = pmd_addr_end(addr, end); 1018 if (pmd_trans_huge(*pmd)) { 1019 if (next-addr != HPAGE_PMD_SIZE) { 1020 VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem)); 1021 split_huge_page_pmd(vma->vm_mm, pmd); 1022 } else if (zap_huge_pmd(tlb, vma, pmd)) { 1023 (*zap_work)--; 1024 continue; 1025 } 1026 /* fall through */ 1027 } 1028 if (pmd_none_or_clear_bad(pmd)) { 1029 (*zap_work)--; 1030 continue; 1031 } 1032 next = zap_pte_range(tlb, vma, pmd, addr, next, 1033 zap_work, details); 1034 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 1035 1036 return addr; 1037} 1038 1039static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 1040 struct vm_area_struct *vma, pgd_t *pgd, 1041 unsigned long addr, unsigned long end, 1042 long *zap_work, struct zap_details *details) 1043{ 1044 pud_t *pud; 1045 unsigned long next; 1046 1047 pud = pud_offset(pgd, addr); 1048 do { 1049 next = pud_addr_end(addr, end); 1050 if (pud_none_or_clear_bad(pud)) { 1051 (*zap_work)--; 1052 continue; 1053 } 1054 next = zap_pmd_range(tlb, vma, pud, addr, next, 1055 zap_work, details); 1056 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 1057 1058 return addr; 1059} 1060 1061static unsigned long unmap_page_range(struct mmu_gather *tlb, 1062 struct vm_area_struct *vma, 1063 unsigned long addr, unsigned long end, 1064 long *zap_work, struct zap_details *details) 1065{ 1066 pgd_t *pgd; 1067 unsigned long next; 1068 1069 if (details && !details->check_mapping && !details->nonlinear_vma) 1070 details = NULL; 1071 1072 BUG_ON(addr >= end); 1073 mem_cgroup_uncharge_start(); 1074 tlb_start_vma(tlb, vma); 1075 pgd = pgd_offset(vma->vm_mm, addr); 1076 do { 1077 next = pgd_addr_end(addr, end); 1078 if (pgd_none_or_clear_bad(pgd)) { 1079 (*zap_work)--; 1080 continue; 1081 } 1082 next = zap_pud_range(tlb, vma, pgd, addr, next, 1083 zap_work, details); 1084 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 1085 tlb_end_vma(tlb, vma); 1086 mem_cgroup_uncharge_end(); 1087 1088 return addr; 1089} 1090 1091#ifdef CONFIG_PREEMPT 1092# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 1093#else 1094/* No preempt: go for improved straight-line efficiency */ 1095# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 1096#endif 1097 1098/** 1099 * unmap_vmas - unmap a range of memory covered by a list of vma's 1100 * @tlbp: address of the caller's struct mmu_gather 1101 * @vma: the starting vma 1102 * @start_addr: virtual address at which to start unmapping 1103 * @end_addr: virtual address at which to end unmapping 1104 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 1105 * @details: details of nonlinear truncation or shared cache invalidation 1106 * 1107 * Returns the end address of the unmapping (restart addr if interrupted). 1108 * 1109 * Unmap all pages in the vma list. 1110 * 1111 * We aim to not hold locks for too long (for scheduling latency reasons). 1112 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 1113 * return the ending mmu_gather to the caller. 1114 * 1115 * Only addresses between `start' and `end' will be unmapped. 1116 * 1117 * The VMA list must be sorted in ascending virtual address order. 1118 * 1119 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1120 * range after unmap_vmas() returns. So the only responsibility here is to 1121 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1122 * drops the lock and schedules. 1123 */ 1124unsigned long unmap_vmas(struct mmu_gather **tlbp, 1125 struct vm_area_struct *vma, unsigned long start_addr, 1126 unsigned long end_addr, unsigned long *nr_accounted, 1127 struct zap_details *details) 1128{ 1129 long zap_work = ZAP_BLOCK_SIZE; 1130 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 1131 int tlb_start_valid = 0; 1132 unsigned long start = start_addr; 1133 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 1134 int fullmm = (*tlbp)->fullmm; 1135 struct mm_struct *mm = vma->vm_mm; 1136 1137 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1138 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 1139 unsigned long end; 1140 1141 start = max(vma->vm_start, start_addr); 1142 if (start >= vma->vm_end) 1143 continue; 1144 end = min(vma->vm_end, end_addr); 1145 if (end <= vma->vm_start) 1146 continue; 1147 1148 if (vma->vm_flags & VM_ACCOUNT) 1149 *nr_accounted += (end - start) >> PAGE_SHIFT; 1150 1151 if (unlikely(is_pfn_mapping(vma))) 1152 untrack_pfn_vma(vma, 0, 0); 1153 1154 while (start != end) { 1155 if (!tlb_start_valid) { 1156 tlb_start = start; 1157 tlb_start_valid = 1; 1158 } 1159 1160 if (unlikely(is_vm_hugetlb_page(vma))) { 1161 /* 1162 * It is undesirable to test vma->vm_file as it 1163 * should be non-null for valid hugetlb area. 1164 * However, vm_file will be NULL in the error 1165 * cleanup path of do_mmap_pgoff. When 1166 * hugetlbfs ->mmap method fails, 1167 * do_mmap_pgoff() nullifies vma->vm_file 1168 * before calling this function to clean up. 1169 * Since no pte has actually been setup, it is 1170 * safe to do nothing in this case. 1171 */ 1172 if (vma->vm_file) { 1173 unmap_hugepage_range(vma, start, end, NULL); 1174 zap_work -= (end - start) / 1175 pages_per_huge_page(hstate_vma(vma)); 1176 } 1177 1178 start = end; 1179 } else 1180 start = unmap_page_range(*tlbp, vma, 1181 start, end, &zap_work, details); 1182 1183 if (zap_work > 0) { 1184 BUG_ON(start != end); 1185 break; 1186 } 1187 1188 tlb_finish_mmu(*tlbp, tlb_start, start); 1189 1190 if (need_resched() || 1191 (i_mmap_lock && spin_needbreak(i_mmap_lock))) { 1192 if (i_mmap_lock) { 1193 *tlbp = NULL; 1194 goto out; 1195 } 1196 cond_resched(); 1197 } 1198 1199 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 1200 tlb_start_valid = 0; 1201 zap_work = ZAP_BLOCK_SIZE; 1202 } 1203 } 1204out: 1205 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1206 return start; /* which is now the end (or restart) address */ 1207} 1208 1209/** 1210 * zap_page_range - remove user pages in a given range 1211 * @vma: vm_area_struct holding the applicable pages 1212 * @address: starting address of pages to zap 1213 * @size: number of bytes to zap 1214 * @details: details of nonlinear truncation or shared cache invalidation 1215 */ 1216unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 1217 unsigned long size, struct zap_details *details) 1218{ 1219 struct mm_struct *mm = vma->vm_mm; 1220 struct mmu_gather *tlb; 1221 unsigned long end = address + size; 1222 unsigned long nr_accounted = 0; 1223 1224 lru_add_drain(); 1225 tlb = tlb_gather_mmu(mm, 0); 1226 update_hiwater_rss(mm); 1227 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 1228 if (tlb) 1229 tlb_finish_mmu(tlb, address, end); 1230 return end; 1231} 1232 1233/** 1234 * zap_vma_ptes - remove ptes mapping the vma 1235 * @vma: vm_area_struct holding ptes to be zapped 1236 * @address: starting address of pages to zap 1237 * @size: number of bytes to zap 1238 * 1239 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1240 * 1241 * The entire address range must be fully contained within the vma. 1242 * 1243 * Returns 0 if successful. 1244 */ 1245int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1246 unsigned long size) 1247{ 1248 if (address < vma->vm_start || address + size > vma->vm_end || 1249 !(vma->vm_flags & VM_PFNMAP)) 1250 return -1; 1251 zap_page_range(vma, address, size, NULL); 1252 return 0; 1253} 1254EXPORT_SYMBOL_GPL(zap_vma_ptes); 1255 1256/** 1257 * follow_page - look up a page descriptor from a user-virtual address 1258 * @vma: vm_area_struct mapping @address 1259 * @address: virtual address to look up 1260 * @flags: flags modifying lookup behaviour 1261 * 1262 * @flags can have FOLL_ flags set, defined in <linux/mm.h> 1263 * 1264 * Returns the mapped (struct page *), %NULL if no mapping exists, or 1265 * an error pointer if there is a mapping to something not represented 1266 * by a page descriptor (see also vm_normal_page()). 1267 */ 1268struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1269 unsigned int flags) 1270{ 1271 pgd_t *pgd; 1272 pud_t *pud; 1273 pmd_t *pmd; 1274 pte_t *ptep, pte; 1275 spinlock_t *ptl; 1276 struct page *page; 1277 struct mm_struct *mm = vma->vm_mm; 1278 1279 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 1280 if (!IS_ERR(page)) { 1281 BUG_ON(flags & FOLL_GET); 1282 goto out; 1283 } 1284 1285 page = NULL; 1286 pgd = pgd_offset(mm, address); 1287 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 1288 goto no_page_table; 1289 1290 pud = pud_offset(pgd, address); 1291 if (pud_none(*pud)) 1292 goto no_page_table; 1293 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) { 1294 BUG_ON(flags & FOLL_GET); 1295 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); 1296 goto out; 1297 } 1298 if (unlikely(pud_bad(*pud))) 1299 goto no_page_table; 1300 1301 pmd = pmd_offset(pud, address); 1302 if (pmd_none(*pmd)) 1303 goto no_page_table; 1304 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) { 1305 BUG_ON(flags & FOLL_GET); 1306 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 1307 goto out; 1308 } 1309 if (pmd_trans_huge(*pmd)) { 1310 if (flags & FOLL_SPLIT) { 1311 split_huge_page_pmd(mm, pmd); 1312 goto split_fallthrough; 1313 } 1314 spin_lock(&mm->page_table_lock); 1315 if (likely(pmd_trans_huge(*pmd))) { 1316 if (unlikely(pmd_trans_splitting(*pmd))) { 1317 spin_unlock(&mm->page_table_lock); 1318 wait_split_huge_page(vma->anon_vma, pmd); 1319 } else { 1320 page = follow_trans_huge_pmd(mm, address, 1321 pmd, flags); 1322 spin_unlock(&mm->page_table_lock); 1323 goto out; 1324 } 1325 } else 1326 spin_unlock(&mm->page_table_lock); 1327 /* fall through */ 1328 } 1329split_fallthrough: 1330 if (unlikely(pmd_bad(*pmd))) 1331 goto no_page_table; 1332 1333 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 1334 1335 pte = *ptep; 1336 if (!pte_present(pte)) 1337 goto no_page; 1338 if ((flags & FOLL_WRITE) && !pte_write(pte)) 1339 goto unlock; 1340 1341 page = vm_normal_page(vma, address, pte); 1342 if (unlikely(!page)) { 1343 if ((flags & FOLL_DUMP) || 1344 !is_zero_pfn(pte_pfn(pte))) 1345 goto bad_page; 1346 page = pte_page(pte); 1347 } 1348 1349 if (flags & FOLL_GET) 1350 get_page(page); 1351 if (flags & FOLL_TOUCH) { 1352 if ((flags & FOLL_WRITE) && 1353 !pte_dirty(pte) && !PageDirty(page)) 1354 set_page_dirty(page); 1355 /* 1356 * pte_mkyoung() would be more correct here, but atomic care 1357 * is needed to avoid losing the dirty bit: it is easier to use 1358 * mark_page_accessed(). 1359 */ 1360 mark_page_accessed(page); 1361 } 1362 if (flags & FOLL_MLOCK) { 1363 /* 1364 * The preliminary mapping check is mainly to avoid the 1365 * pointless overhead of lock_page on the ZERO_PAGE 1366 * which might bounce very badly if there is contention. 1367 * 1368 * If the page is already locked, we don't need to 1369 * handle it now - vmscan will handle it later if and 1370 * when it attempts to reclaim the page. 1371 */ 1372 if (page->mapping && trylock_page(page)) { 1373 lru_add_drain(); /* push cached pages to LRU */ 1374 /* 1375 * Because we lock page here and migration is 1376 * blocked by the pte's page reference, we need 1377 * only check for file-cache page truncation. 1378 */ 1379 if (page->mapping) 1380 mlock_vma_page(page); 1381 unlock_page(page); 1382 } 1383 } 1384unlock: 1385 pte_unmap_unlock(ptep, ptl); 1386out: 1387 return page; 1388 1389bad_page: 1390 pte_unmap_unlock(ptep, ptl); 1391 return ERR_PTR(-EFAULT); 1392 1393no_page: 1394 pte_unmap_unlock(ptep, ptl); 1395 if (!pte_none(pte)) 1396 return page; 1397 1398no_page_table: 1399 /* 1400 * When core dumping an enormous anonymous area that nobody 1401 * has touched so far, we don't want to allocate unnecessary pages or 1402 * page tables. Return error instead of NULL to skip handle_mm_fault, 1403 * then get_dump_page() will return NULL to leave a hole in the dump. 1404 * But we can only make this optimization where a hole would surely 1405 * be zero-filled if handle_mm_fault() actually did handle it. 1406 */ 1407 if ((flags & FOLL_DUMP) && 1408 (!vma->vm_ops || !vma->vm_ops->fault)) 1409 return ERR_PTR(-EFAULT); 1410 return page; 1411} 1412 1413static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr) 1414{ 1415 return (vma->vm_flags & VM_GROWSDOWN) && 1416 (vma->vm_start == addr) && 1417 !vma_stack_continue(vma->vm_prev, addr); 1418} 1419 1420/** 1421 * __get_user_pages() - pin user pages in memory 1422 * @tsk: task_struct of target task 1423 * @mm: mm_struct of target mm 1424 * @start: starting user address 1425 * @nr_pages: number of pages from start to pin 1426 * @gup_flags: flags modifying pin behaviour 1427 * @pages: array that receives pointers to the pages pinned. 1428 * Should be at least nr_pages long. Or NULL, if caller 1429 * only intends to ensure the pages are faulted in. 1430 * @vmas: array of pointers to vmas corresponding to each page. 1431 * Or NULL if the caller does not require them. 1432 * @nonblocking: whether waiting for disk IO or mmap_sem contention 1433 * 1434 * Returns number of pages pinned. This may be fewer than the number 1435 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1436 * were pinned, returns -errno. Each page returned must be released 1437 * with a put_page() call when it is finished with. vmas will only 1438 * remain valid while mmap_sem is held. 1439 * 1440 * Must be called with mmap_sem held for read or write. 1441 * 1442 * __get_user_pages walks a process's page tables and takes a reference to 1443 * each struct page that each user address corresponds to at a given 1444 * instant. That is, it takes the page that would be accessed if a user 1445 * thread accesses the given user virtual address at that instant. 1446 * 1447 * This does not guarantee that the page exists in the user mappings when 1448 * __get_user_pages returns, and there may even be a completely different 1449 * page there in some cases (eg. if mmapped pagecache has been invalidated 1450 * and subsequently re faulted). However it does guarantee that the page 1451 * won't be freed completely. And mostly callers simply care that the page 1452 * contains data that was valid *at some point in time*. Typically, an IO 1453 * or similar operation cannot guarantee anything stronger anyway because 1454 * locks can't be held over the syscall boundary. 1455 * 1456 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If 1457 * the page is written to, set_page_dirty (or set_page_dirty_lock, as 1458 * appropriate) must be called after the page is finished with, and 1459 * before put_page is called. 1460 * 1461 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO 1462 * or mmap_sem contention, and if waiting is needed to pin all pages, 1463 * *@nonblocking will be set to 0. 1464 * 1465 * In most cases, get_user_pages or get_user_pages_fast should be used 1466 * instead of __get_user_pages. __get_user_pages should be used only if 1467 * you need some special @gup_flags. 1468 */ 1469int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1470 unsigned long start, int nr_pages, unsigned int gup_flags, 1471 struct page **pages, struct vm_area_struct **vmas, 1472 int *nonblocking) 1473{ 1474 int i; 1475 unsigned long vm_flags; 1476 1477 if (nr_pages <= 0) 1478 return 0; 1479 1480 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); 1481 1482 /* 1483 * Require read or write permissions. 1484 * If FOLL_FORCE is set, we only require the "MAY" flags. 1485 */ 1486 vm_flags = (gup_flags & FOLL_WRITE) ? 1487 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 1488 vm_flags &= (gup_flags & FOLL_FORCE) ? 1489 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 1490 i = 0; 1491 1492 do { 1493 struct vm_area_struct *vma; 1494 1495 vma = find_extend_vma(mm, start); 1496 if (!vma && in_gate_area(mm, start)) { 1497 unsigned long pg = start & PAGE_MASK; 1498 pgd_t *pgd; 1499 pud_t *pud; 1500 pmd_t *pmd; 1501 pte_t *pte; 1502 1503 /* user gate pages are read-only */ 1504 if (gup_flags & FOLL_WRITE) 1505 return i ? : -EFAULT; 1506 if (pg > TASK_SIZE) 1507 pgd = pgd_offset_k(pg); 1508 else 1509 pgd = pgd_offset_gate(mm, pg); 1510 BUG_ON(pgd_none(*pgd)); 1511 pud = pud_offset(pgd, pg); 1512 BUG_ON(pud_none(*pud)); 1513 pmd = pmd_offset(pud, pg); 1514 if (pmd_none(*pmd)) 1515 return i ? : -EFAULT; 1516 VM_BUG_ON(pmd_trans_huge(*pmd)); 1517 pte = pte_offset_map(pmd, pg); 1518 if (pte_none(*pte)) { 1519 pte_unmap(pte); 1520 return i ? : -EFAULT; 1521 } 1522 vma = get_gate_vma(mm); 1523 if (pages) { 1524 struct page *page; 1525 1526 page = vm_normal_page(vma, start, *pte); 1527 if (!page) { 1528 if (!(gup_flags & FOLL_DUMP) && 1529 is_zero_pfn(pte_pfn(*pte))) 1530 page = pte_page(*pte); 1531 else { 1532 pte_unmap(pte); 1533 return i ? : -EFAULT; 1534 } 1535 } 1536 pages[i] = page; 1537 get_page(page); 1538 } 1539 pte_unmap(pte); 1540 goto next_page; 1541 } 1542 1543 if (!vma || 1544 (vma->vm_flags & (VM_IO | VM_PFNMAP)) || 1545 !(vm_flags & vma->vm_flags)) 1546 return i ? : -EFAULT; 1547 1548 if (is_vm_hugetlb_page(vma)) { 1549 i = follow_hugetlb_page(mm, vma, pages, vmas, 1550 &start, &nr_pages, i, gup_flags); 1551 continue; 1552 } 1553 1554 /* 1555 * If we don't actually want the page itself, 1556 * and it's the stack guard page, just skip it. 1557 */ 1558 if (!pages && stack_guard_page(vma, start)) 1559 goto next_page; 1560 1561 do { 1562 struct page *page; 1563 unsigned int foll_flags = gup_flags; 1564 1565 /* 1566 * If we have a pending SIGKILL, don't keep faulting 1567 * pages and potentially allocating memory. 1568 */ 1569 if (unlikely(fatal_signal_pending(current))) 1570 return i ? i : -ERESTARTSYS; 1571 1572 cond_resched(); 1573 while (!(page = follow_page(vma, start, foll_flags))) { 1574 int ret; 1575 unsigned int fault_flags = 0; 1576 1577 if (foll_flags & FOLL_WRITE) 1578 fault_flags |= FAULT_FLAG_WRITE; 1579 if (nonblocking) 1580 fault_flags |= FAULT_FLAG_ALLOW_RETRY; 1581 if (foll_flags & FOLL_NOWAIT) 1582 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT); 1583 1584 ret = handle_mm_fault(mm, vma, start, 1585 fault_flags); 1586 1587 if (ret & VM_FAULT_ERROR) { 1588 if (ret & VM_FAULT_OOM) 1589 return i ? i : -ENOMEM; 1590 if (ret & (VM_FAULT_HWPOISON | 1591 VM_FAULT_HWPOISON_LARGE)) { 1592 if (i) 1593 return i; 1594 else if (gup_flags & FOLL_HWPOISON) 1595 return -EHWPOISON; 1596 else 1597 return -EFAULT; 1598 } 1599 if (ret & VM_FAULT_SIGBUS) 1600 return i ? i : -EFAULT; 1601 BUG(); 1602 } 1603 1604 if (tsk) { 1605 if (ret & VM_FAULT_MAJOR) 1606 tsk->maj_flt++; 1607 else 1608 tsk->min_flt++; 1609 } 1610 1611 if (ret & VM_FAULT_RETRY) { 1612 if (nonblocking) 1613 *nonblocking = 0; 1614 return i; 1615 } 1616 1617 /* 1618 * The VM_FAULT_WRITE bit tells us that 1619 * do_wp_page has broken COW when necessary, 1620 * even if maybe_mkwrite decided not to set 1621 * pte_write. We can thus safely do subsequent 1622 * page lookups as if they were reads. But only 1623 * do so when looping for pte_write is futile: 1624 * in some cases userspace may also be wanting 1625 * to write to the gotten user page, which a 1626 * read fault here might prevent (a readonly 1627 * page might get reCOWed by userspace write). 1628 */ 1629 if ((ret & VM_FAULT_WRITE) && 1630 !(vma->vm_flags & VM_WRITE)) 1631 foll_flags &= ~FOLL_WRITE; 1632 1633 cond_resched(); 1634 } 1635 if (IS_ERR(page)) 1636 return i ? i : PTR_ERR(page); 1637 if (pages) { 1638 pages[i] = page; 1639 1640 flush_anon_page(vma, page, start); 1641 flush_dcache_page(page); 1642 } 1643next_page: 1644 if (vmas) 1645 vmas[i] = vma; 1646 i++; 1647 start += PAGE_SIZE; 1648 nr_pages--; 1649 } while (nr_pages && start < vma->vm_end); 1650 } while (nr_pages); 1651 return i; 1652} 1653EXPORT_SYMBOL(__get_user_pages); 1654 1655/** 1656 * get_user_pages() - pin user pages in memory 1657 * @tsk: the task_struct to use for page fault accounting, or 1658 * NULL if faults are not to be recorded. 1659 * @mm: mm_struct of target mm 1660 * @start: starting user address 1661 * @nr_pages: number of pages from start to pin 1662 * @write: whether pages will be written to by the caller 1663 * @force: whether to force write access even if user mapping is 1664 * readonly. This will result in the page being COWed even 1665 * in MAP_SHARED mappings. You do not want this. 1666 * @pages: array that receives pointers to the pages pinned. 1667 * Should be at least nr_pages long. Or NULL, if caller 1668 * only intends to ensure the pages are faulted in. 1669 * @vmas: array of pointers to vmas corresponding to each page. 1670 * Or NULL if the caller does not require them. 1671 * 1672 * Returns number of pages pinned. This may be fewer than the number 1673 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1674 * were pinned, returns -errno. Each page returned must be released 1675 * with a put_page() call when it is finished with. vmas will only 1676 * remain valid while mmap_sem is held. 1677 * 1678 * Must be called with mmap_sem held for read or write. 1679 * 1680 * get_user_pages walks a process's page tables and takes a reference to 1681 * each struct page that each user address corresponds to at a given 1682 * instant. That is, it takes the page that would be accessed if a user 1683 * thread accesses the given user virtual address at that instant. 1684 * 1685 * This does not guarantee that the page exists in the user mappings when 1686 * get_user_pages returns, and there may even be a completely different 1687 * page there in some cases (eg. if mmapped pagecache has been invalidated 1688 * and subsequently re faulted). However it does guarantee that the page 1689 * won't be freed completely. And mostly callers simply care that the page 1690 * contains data that was valid *at some point in time*. Typically, an IO 1691 * or similar operation cannot guarantee anything stronger anyway because 1692 * locks can't be held over the syscall boundary. 1693 * 1694 * If write=0, the page must not be written to. If the page is written to, 1695 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called 1696 * after the page is finished with, and before put_page is called. 1697 * 1698 * get_user_pages is typically used for fewer-copy IO operations, to get a 1699 * handle on the memory by some means other than accesses via the user virtual 1700 * addresses. The pages may be submitted for DMA to devices or accessed via 1701 * their kernel linear mapping (via the kmap APIs). Care should be taken to 1702 * use the correct cache flushing APIs. 1703 * 1704 * See also get_user_pages_fast, for performance critical applications. 1705 */ 1706int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1707 unsigned long start, int nr_pages, int write, int force, 1708 struct page **pages, struct vm_area_struct **vmas) 1709{ 1710 int flags = FOLL_TOUCH; 1711 1712 if (pages) 1713 flags |= FOLL_GET; 1714 if (write) 1715 flags |= FOLL_WRITE; 1716 if (force) 1717 flags |= FOLL_FORCE; 1718 1719 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 1720 NULL); 1721} 1722EXPORT_SYMBOL(get_user_pages); 1723 1724/** 1725 * get_dump_page() - pin user page in memory while writing it to core dump 1726 * @addr: user address 1727 * 1728 * Returns struct page pointer of user page pinned for dump, 1729 * to be freed afterwards by page_cache_release() or put_page(). 1730 * 1731 * Returns NULL on any kind of failure - a hole must then be inserted into 1732 * the corefile, to preserve alignment with its headers; and also returns 1733 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - 1734 * allowing a hole to be left in the corefile to save diskspace. 1735 * 1736 * Called without mmap_sem, but after all other threads have been killed. 1737 */ 1738#ifdef CONFIG_ELF_CORE 1739struct page *get_dump_page(unsigned long addr) 1740{ 1741 struct vm_area_struct *vma; 1742 struct page *page; 1743 1744 if (__get_user_pages(current, current->mm, addr, 1, 1745 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma, 1746 NULL) < 1) 1747 return NULL; 1748 flush_cache_page(vma, addr, page_to_pfn(page)); 1749 return page; 1750} 1751#endif /* CONFIG_ELF_CORE */ 1752 1753pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr, 1754 spinlock_t **ptl) 1755{ 1756 pgd_t * pgd = pgd_offset(mm, addr); 1757 pud_t * pud = pud_alloc(mm, pgd, addr); 1758 if (pud) { 1759 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1760 if (pmd) { 1761 VM_BUG_ON(pmd_trans_huge(*pmd)); 1762 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1763 } 1764 } 1765 return NULL; 1766} 1767 1768/* 1769 * This is the old fallback for page remapping. 1770 * 1771 * For historical reasons, it only allows reserved pages. Only 1772 * old drivers should use this, and they needed to mark their 1773 * pages reserved for the old functions anyway. 1774 */ 1775static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1776 struct page *page, pgprot_t prot) 1777{ 1778 struct mm_struct *mm = vma->vm_mm; 1779 int retval; 1780 pte_t *pte; 1781 spinlock_t *ptl; 1782 1783 retval = -EINVAL; 1784 if (PageAnon(page)) 1785 goto out; 1786 retval = -ENOMEM; 1787 flush_dcache_page(page); 1788 pte = get_locked_pte(mm, addr, &ptl); 1789 if (!pte) 1790 goto out; 1791 retval = -EBUSY; 1792 if (!pte_none(*pte)) 1793 goto out_unlock; 1794 1795 /* Ok, finally just insert the thing.. */ 1796 get_page(page); 1797 inc_mm_counter_fast(mm, MM_FILEPAGES); 1798 page_add_file_rmap(page); 1799 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1800 1801 retval = 0; 1802 pte_unmap_unlock(pte, ptl); 1803 return retval; 1804out_unlock: 1805 pte_unmap_unlock(pte, ptl); 1806out: 1807 return retval; 1808} 1809 1810/** 1811 * vm_insert_page - insert single page into user vma 1812 * @vma: user vma to map to 1813 * @addr: target user address of this page 1814 * @page: source kernel page 1815 * 1816 * This allows drivers to insert individual pages they've allocated 1817 * into a user vma. 1818 * 1819 * The page has to be a nice clean _individual_ kernel allocation. 1820 * If you allocate a compound page, you need to have marked it as 1821 * such (__GFP_COMP), or manually just split the page up yourself 1822 * (see split_page()). 1823 * 1824 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1825 * took an arbitrary page protection parameter. This doesn't allow 1826 * that. Your vma protection will have to be set up correctly, which 1827 * means that if you want a shared writable mapping, you'd better 1828 * ask for a shared writable mapping! 1829 * 1830 * The page does not need to be reserved. 1831 */ 1832int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1833 struct page *page) 1834{ 1835 if (addr < vma->vm_start || addr >= vma->vm_end) 1836 return -EFAULT; 1837 if (!page_count(page)) 1838 return -EINVAL; 1839 vma->vm_flags |= VM_INSERTPAGE; 1840 return insert_page(vma, addr, page, vma->vm_page_prot); 1841} 1842EXPORT_SYMBOL(vm_insert_page); 1843 1844static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1845 unsigned long pfn, pgprot_t prot) 1846{ 1847 struct mm_struct *mm = vma->vm_mm; 1848 int retval; 1849 pte_t *pte, entry; 1850 spinlock_t *ptl; 1851 1852 retval = -ENOMEM; 1853 pte = get_locked_pte(mm, addr, &ptl); 1854 if (!pte) 1855 goto out; 1856 retval = -EBUSY; 1857 if (!pte_none(*pte)) 1858 goto out_unlock; 1859 1860 /* Ok, finally just insert the thing.. */ 1861 entry = pte_mkspecial(pfn_pte(pfn, prot)); 1862 set_pte_at(mm, addr, pte, entry); 1863 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */ 1864 1865 retval = 0; 1866out_unlock: 1867 pte_unmap_unlock(pte, ptl); 1868out: 1869 return retval; 1870} 1871 1872/** 1873 * vm_insert_pfn - insert single pfn into user vma 1874 * @vma: user vma to map to 1875 * @addr: target user address of this page 1876 * @pfn: source kernel pfn 1877 * 1878 * Similar to vm_inert_page, this allows drivers to insert individual pages 1879 * they've allocated into a user vma. Same comments apply. 1880 * 1881 * This function should only be called from a vm_ops->fault handler, and 1882 * in that case the handler should return NULL. 1883 * 1884 * vma cannot be a COW mapping. 1885 * 1886 * As this is called only for pages that do not currently exist, we 1887 * do not need to flush old virtual caches or the TLB. 1888 */ 1889int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1890 unsigned long pfn) 1891{ 1892 int ret; 1893 pgprot_t pgprot = vma->vm_page_prot; 1894 /* 1895 * Technically, architectures with pte_special can avoid all these 1896 * restrictions (same for remap_pfn_range). However we would like 1897 * consistency in testing and feature parity among all, so we should 1898 * try to keep these invariants in place for everybody. 1899 */ 1900 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 1901 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1902 (VM_PFNMAP|VM_MIXEDMAP)); 1903 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1904 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 1905 1906 if (addr < vma->vm_start || addr >= vma->vm_end) 1907 return -EFAULT; 1908 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE)) 1909 return -EINVAL; 1910 1911 ret = insert_pfn(vma, addr, pfn, pgprot); 1912 1913 if (ret) 1914 untrack_pfn_vma(vma, pfn, PAGE_SIZE); 1915 1916 return ret; 1917} 1918EXPORT_SYMBOL(vm_insert_pfn); 1919 1920int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1921 unsigned long pfn) 1922{ 1923 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 1924 1925 if (addr < vma->vm_start || addr >= vma->vm_end) 1926 return -EFAULT; 1927 1928 /* 1929 * If we don't have pte special, then we have to use the pfn_valid() 1930 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 1931 * refcount the page if pfn_valid is true (hence insert_page rather 1932 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 1933 * without pte special, it would there be refcounted as a normal page. 1934 */ 1935 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 1936 struct page *page; 1937 1938 page = pfn_to_page(pfn); 1939 return insert_page(vma, addr, page, vma->vm_page_prot); 1940 } 1941 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 1942} 1943EXPORT_SYMBOL(vm_insert_mixed); 1944 1945/* 1946 * maps a range of physical memory into the requested pages. the old 1947 * mappings are removed. any references to nonexistent pages results 1948 * in null mappings (currently treated as "copy-on-access") 1949 */ 1950static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1951 unsigned long addr, unsigned long end, 1952 unsigned long pfn, pgprot_t prot) 1953{ 1954 pte_t *pte; 1955 spinlock_t *ptl; 1956 1957 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1958 if (!pte) 1959 return -ENOMEM; 1960 arch_enter_lazy_mmu_mode(); 1961 do { 1962 BUG_ON(!pte_none(*pte)); 1963 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 1964 pfn++; 1965 } while (pte++, addr += PAGE_SIZE, addr != end); 1966 arch_leave_lazy_mmu_mode(); 1967 pte_unmap_unlock(pte - 1, ptl); 1968 return 0; 1969} 1970 1971static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1972 unsigned long addr, unsigned long end, 1973 unsigned long pfn, pgprot_t prot) 1974{ 1975 pmd_t *pmd; 1976 unsigned long next; 1977 1978 pfn -= addr >> PAGE_SHIFT; 1979 pmd = pmd_alloc(mm, pud, addr); 1980 if (!pmd) 1981 return -ENOMEM; 1982 VM_BUG_ON(pmd_trans_huge(*pmd)); 1983 do { 1984 next = pmd_addr_end(addr, end); 1985 if (remap_pte_range(mm, pmd, addr, next, 1986 pfn + (addr >> PAGE_SHIFT), prot)) 1987 return -ENOMEM; 1988 } while (pmd++, addr = next, addr != end); 1989 return 0; 1990} 1991 1992static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1993 unsigned long addr, unsigned long end, 1994 unsigned long pfn, pgprot_t prot) 1995{ 1996 pud_t *pud; 1997 unsigned long next; 1998 1999 pfn -= addr >> PAGE_SHIFT; 2000 pud = pud_alloc(mm, pgd, addr); 2001 if (!pud) 2002 return -ENOMEM; 2003 do { 2004 next = pud_addr_end(addr, end); 2005 if (remap_pmd_range(mm, pud, addr, next, 2006 pfn + (addr >> PAGE_SHIFT), prot)) 2007 return -ENOMEM; 2008 } while (pud++, addr = next, addr != end); 2009 return 0; 2010} 2011 2012/** 2013 * remap_pfn_range - remap kernel memory to userspace 2014 * @vma: user vma to map to 2015 * @addr: target user address to start at 2016 * @pfn: physical address of kernel memory 2017 * @size: size of map area 2018 * @prot: page protection flags for this mapping 2019 * 2020 * Note: this is only safe if the mm semaphore is held when called. 2021 */ 2022int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 2023 unsigned long pfn, unsigned long size, pgprot_t prot) 2024{ 2025 pgd_t *pgd; 2026 unsigned long next; 2027 unsigned long end = addr + PAGE_ALIGN(size); 2028 struct mm_struct *mm = vma->vm_mm; 2029 int err; 2030 2031 /* 2032 * Physically remapped pages are special. Tell the 2033 * rest of the world about it: 2034 * VM_IO tells people not to look at these pages 2035 * (accesses can have side effects). 2036 * VM_RESERVED is specified all over the place, because 2037 * in 2.4 it kept swapout's vma scan off this vma; but 2038 * in 2.6 the LRU scan won't even find its pages, so this 2039 * flag means no more than count its pages in reserved_vm, 2040 * and omit it from core dump, even when VM_IO turned off. 2041 * VM_PFNMAP tells the core MM that the base pages are just 2042 * raw PFN mappings, and do not have a "struct page" associated 2043 * with them. 2044 * 2045 * There's a horrible special case to handle copy-on-write 2046 * behaviour that some programs depend on. We mark the "original" 2047 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 2048 */ 2049 if (addr == vma->vm_start && end == vma->vm_end) { 2050 vma->vm_pgoff = pfn; 2051 vma->vm_flags |= VM_PFN_AT_MMAP; 2052 } else if (is_cow_mapping(vma->vm_flags)) 2053 return -EINVAL; 2054 2055 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 2056 2057 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size)); 2058 if (err) { 2059 /* 2060 * To indicate that track_pfn related cleanup is not 2061 * needed from higher level routine calling unmap_vmas 2062 */ 2063 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP); 2064 vma->vm_flags &= ~VM_PFN_AT_MMAP; 2065 return -EINVAL; 2066 } 2067 2068 BUG_ON(addr >= end); 2069 pfn -= addr >> PAGE_SHIFT; 2070 pgd = pgd_offset(mm, addr); 2071 flush_cache_range(vma, addr, end); 2072 do { 2073 next = pgd_addr_end(addr, end); 2074 err = remap_pud_range(mm, pgd, addr, next, 2075 pfn + (addr >> PAGE_SHIFT), prot); 2076 if (err) 2077 break; 2078 } while (pgd++, addr = next, addr != end); 2079 2080 if (err) 2081 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size)); 2082 2083 return err; 2084} 2085EXPORT_SYMBOL(remap_pfn_range); 2086 2087static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 2088 unsigned long addr, unsigned long end, 2089 pte_fn_t fn, void *data) 2090{ 2091 pte_t *pte; 2092 int err; 2093 pgtable_t token; 2094 spinlock_t *uninitialized_var(ptl); 2095 2096 pte = (mm == &init_mm) ? 2097 pte_alloc_kernel(pmd, addr) : 2098 pte_alloc_map_lock(mm, pmd, addr, &ptl); 2099 if (!pte) 2100 return -ENOMEM; 2101 2102 BUG_ON(pmd_huge(*pmd)); 2103 2104 arch_enter_lazy_mmu_mode(); 2105 2106 token = pmd_pgtable(*pmd); 2107 2108 do { 2109 err = fn(pte++, token, addr, data); 2110 if (err) 2111 break; 2112 } while (addr += PAGE_SIZE, addr != end); 2113 2114 arch_leave_lazy_mmu_mode(); 2115 2116 if (mm != &init_mm) 2117 pte_unmap_unlock(pte-1, ptl); 2118 return err; 2119} 2120 2121static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 2122 unsigned long addr, unsigned long end, 2123 pte_fn_t fn, void *data) 2124{ 2125 pmd_t *pmd; 2126 unsigned long next; 2127 int err; 2128 2129 BUG_ON(pud_huge(*pud)); 2130 2131 pmd = pmd_alloc(mm, pud, addr); 2132 if (!pmd) 2133 return -ENOMEM; 2134 do { 2135 next = pmd_addr_end(addr, end); 2136 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 2137 if (err) 2138 break; 2139 } while (pmd++, addr = next, addr != end); 2140 return err; 2141} 2142 2143static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 2144 unsigned long addr, unsigned long end, 2145 pte_fn_t fn, void *data) 2146{ 2147 pud_t *pud; 2148 unsigned long next; 2149 int err; 2150 2151 pud = pud_alloc(mm, pgd, addr); 2152 if (!pud) 2153 return -ENOMEM; 2154 do { 2155 next = pud_addr_end(addr, end); 2156 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 2157 if (err) 2158 break; 2159 } while (pud++, addr = next, addr != end); 2160 return err; 2161} 2162 2163/* 2164 * Scan a region of virtual memory, filling in page tables as necessary 2165 * and calling a provided function on each leaf page table. 2166 */ 2167int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 2168 unsigned long size, pte_fn_t fn, void *data) 2169{ 2170 pgd_t *pgd; 2171 unsigned long next; 2172 unsigned long end = addr + size; 2173 int err; 2174 2175 BUG_ON(addr >= end); 2176 pgd = pgd_offset(mm, addr); 2177 do { 2178 next = pgd_addr_end(addr, end); 2179 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 2180 if (err) 2181 break; 2182 } while (pgd++, addr = next, addr != end); 2183 2184 return err; 2185} 2186EXPORT_SYMBOL_GPL(apply_to_page_range); 2187 2188/* 2189 * handle_pte_fault chooses page fault handler according to an entry 2190 * which was read non-atomically. Before making any commitment, on 2191 * those architectures or configurations (e.g. i386 with PAE) which 2192 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault 2193 * must check under lock before unmapping the pte and proceeding 2194 * (but do_wp_page is only called after already making such a check; 2195 * and do_anonymous_page can safely check later on). 2196 */ 2197static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 2198 pte_t *page_table, pte_t orig_pte) 2199{ 2200 int same = 1; 2201#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 2202 if (sizeof(pte_t) > sizeof(unsigned long)) { 2203 spinlock_t *ptl = pte_lockptr(mm, pmd); 2204 spin_lock(ptl); 2205 same = pte_same(*page_table, orig_pte); 2206 spin_unlock(ptl); 2207 } 2208#endif 2209 pte_unmap(page_table); 2210 return same; 2211} 2212 2213static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 2214{ 2215 /* 2216 * If the source page was a PFN mapping, we don't have 2217 * a "struct page" for it. We do a best-effort copy by 2218 * just copying from the original user address. If that 2219 * fails, we just zero-fill it. Live with it. 2220 */ 2221 if (unlikely(!src)) { 2222 void *kaddr = kmap_atomic(dst, KM_USER0); 2223 void __user *uaddr = (void __user *)(va & PAGE_MASK); 2224 2225 /* 2226 * This really shouldn't fail, because the page is there 2227 * in the page tables. But it might just be unreadable, 2228 * in which case we just give up and fill the result with 2229 * zeroes. 2230 */ 2231 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 2232 clear_page(kaddr); 2233 kunmap_atomic(kaddr, KM_USER0); 2234 flush_dcache_page(dst); 2235 } else 2236 copy_user_highpage(dst, src, va, vma); 2237} 2238 2239/* 2240 * This routine handles present pages, when users try to write 2241 * to a shared page. It is done by copying the page to a new address 2242 * and decrementing the shared-page counter for the old page. 2243 * 2244 * Note that this routine assumes that the protection checks have been 2245 * done by the caller (the low-level page fault routine in most cases). 2246 * Thus we can safely just mark it writable once we've done any necessary 2247 * COW. 2248 * 2249 * We also mark the page dirty at this point even though the page will 2250 * change only once the write actually happens. This avoids a few races, 2251 * and potentially makes it more efficient. 2252 * 2253 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2254 * but allow concurrent faults), with pte both mapped and locked. 2255 * We return with mmap_sem still held, but pte unmapped and unlocked. 2256 */ 2257static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 2258 unsigned long address, pte_t *page_table, pmd_t *pmd, 2259 spinlock_t *ptl, pte_t orig_pte) 2260 __releases(ptl) 2261{ 2262 struct page *old_page, *new_page; 2263 pte_t entry; 2264 int ret = 0; 2265 int page_mkwrite = 0; 2266 struct page *dirty_page = NULL; 2267 2268 old_page = vm_normal_page(vma, address, orig_pte); 2269 if (!old_page) { 2270 /* 2271 * VM_MIXEDMAP !pfn_valid() case 2272 * 2273 * We should not cow pages in a shared writeable mapping. 2274 * Just mark the pages writable as we can't do any dirty 2275 * accounting on raw pfn maps. 2276 */ 2277 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2278 (VM_WRITE|VM_SHARED)) 2279 goto reuse; 2280 goto gotten; 2281 } 2282 2283 /* 2284 * Take out anonymous pages first, anonymous shared vmas are 2285 * not dirty accountable. 2286 */ 2287 if (PageAnon(old_page) && !PageKsm(old_page)) { 2288 if (!trylock_page(old_page)) { 2289 page_cache_get(old_page); 2290 pte_unmap_unlock(page_table, ptl); 2291 lock_page(old_page); 2292 page_table = pte_offset_map_lock(mm, pmd, address, 2293 &ptl); 2294 if (!pte_same(*page_table, orig_pte)) { 2295 unlock_page(old_page); 2296 goto unlock; 2297 } 2298 page_cache_release(old_page); 2299 } 2300 if (reuse_swap_page(old_page)) { 2301 /* 2302 * The page is all ours. Move it to our anon_vma so 2303 * the rmap code will not search our parent or siblings. 2304 * Protected against the rmap code by the page lock. 2305 */ 2306 page_move_anon_rmap(old_page, vma, address); 2307 unlock_page(old_page); 2308 goto reuse; 2309 } 2310 unlock_page(old_page); 2311 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2312 (VM_WRITE|VM_SHARED))) { 2313 /* 2314 * Only catch write-faults on shared writable pages, 2315 * read-only shared pages can get COWed by 2316 * get_user_pages(.write=1, .force=1). 2317 */ 2318 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2319 struct vm_fault vmf; 2320 int tmp; 2321 2322 vmf.virtual_address = (void __user *)(address & 2323 PAGE_MASK); 2324 vmf.pgoff = old_page->index; 2325 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2326 vmf.page = old_page; 2327 2328 /* 2329 * Notify the address space that the page is about to 2330 * become writable so that it can prohibit this or wait 2331 * for the page to get into an appropriate state. 2332 * 2333 * We do this without the lock held, so that it can 2334 * sleep if it needs to. 2335 */ 2336 page_cache_get(old_page); 2337 pte_unmap_unlock(page_table, ptl); 2338 2339 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 2340 if (unlikely(tmp & 2341 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2342 ret = tmp; 2343 goto unwritable_page; 2344 } 2345 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 2346 lock_page(old_page); 2347 if (!old_page->mapping) { 2348 ret = 0; /* retry the fault */ 2349 unlock_page(old_page); 2350 goto unwritable_page; 2351 } 2352 } else 2353 VM_BUG_ON(!PageLocked(old_page)); 2354 2355 /* 2356 * Since we dropped the lock we need to revalidate 2357 * the PTE as someone else may have changed it. If 2358 * they did, we just return, as we can count on the 2359 * MMU to tell us if they didn't also make it writable. 2360 */ 2361 page_table = pte_offset_map_lock(mm, pmd, address, 2362 &ptl); 2363 if (!pte_same(*page_table, orig_pte)) { 2364 unlock_page(old_page); 2365 goto unlock; 2366 } 2367 2368 page_mkwrite = 1; 2369 } 2370 dirty_page = old_page; 2371 get_page(dirty_page); 2372 2373reuse: 2374 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2375 entry = pte_mkyoung(orig_pte); 2376 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2377 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2378 update_mmu_cache(vma, address, page_table); 2379 pte_unmap_unlock(page_table, ptl); 2380 ret |= VM_FAULT_WRITE; 2381 2382 if (!dirty_page) 2383 return ret; 2384 2385 /* 2386 * Yes, Virginia, this is actually required to prevent a race 2387 * with clear_page_dirty_for_io() from clearing the page dirty 2388 * bit after it clear all dirty ptes, but before a racing 2389 * do_wp_page installs a dirty pte. 2390 * 2391 * __do_fault is protected similarly. 2392 */ 2393 if (!page_mkwrite) { 2394 wait_on_page_locked(dirty_page); 2395 set_page_dirty_balance(dirty_page, page_mkwrite); 2396 } 2397 put_page(dirty_page); 2398 if (page_mkwrite) { 2399 struct address_space *mapping = dirty_page->mapping; 2400 2401 set_page_dirty(dirty_page); 2402 unlock_page(dirty_page); 2403 page_cache_release(dirty_page); 2404 if (mapping) { 2405 /* 2406 * Some device drivers do not set page.mapping 2407 * but still dirty their pages 2408 */ 2409 balance_dirty_pages_ratelimited(mapping); 2410 } 2411 } 2412 2413 /* file_update_time outside page_lock */ 2414 if (vma->vm_file) 2415 file_update_time(vma->vm_file); 2416 2417 return ret; 2418 } 2419 2420 /* 2421 * Ok, we need to copy. Oh, well.. 2422 */ 2423 page_cache_get(old_page); 2424gotten: 2425 pte_unmap_unlock(page_table, ptl); 2426 2427 if (unlikely(anon_vma_prepare(vma))) 2428 goto oom; 2429 2430 if (is_zero_pfn(pte_pfn(orig_pte))) { 2431 new_page = alloc_zeroed_user_highpage_movable(vma, address); 2432 if (!new_page) 2433 goto oom; 2434 } else { 2435 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2436 if (!new_page) 2437 goto oom; 2438 cow_user_page(new_page, old_page, address, vma); 2439 } 2440 __SetPageUptodate(new_page); 2441 2442 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) 2443 goto oom_free_new; 2444 2445 /* 2446 * Re-check the pte - we dropped the lock 2447 */ 2448 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2449 if (likely(pte_same(*page_table, orig_pte))) { 2450 if (old_page) { 2451 if (!PageAnon(old_page)) { 2452 dec_mm_counter_fast(mm, MM_FILEPAGES); 2453 inc_mm_counter_fast(mm, MM_ANONPAGES); 2454 } 2455 } else 2456 inc_mm_counter_fast(mm, MM_ANONPAGES); 2457 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2458 entry = mk_pte(new_page, vma->vm_page_prot); 2459 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2460 /* 2461 * Clear the pte entry and flush it first, before updating the 2462 * pte with the new entry. This will avoid a race condition 2463 * seen in the presence of one thread doing SMC and another 2464 * thread doing COW. 2465 */ 2466 ptep_clear_flush(vma, address, page_table); 2467 page_add_new_anon_rmap(new_page, vma, address); 2468 /* 2469 * We call the notify macro here because, when using secondary 2470 * mmu page tables (such as kvm shadow page tables), we want the 2471 * new page to be mapped directly into the secondary page table. 2472 */ 2473 set_pte_at_notify(mm, address, page_table, entry); 2474 update_mmu_cache(vma, address, page_table); 2475 if (old_page) { 2476 /* 2477 * Only after switching the pte to the new page may 2478 * we remove the mapcount here. Otherwise another 2479 * process may come and find the rmap count decremented 2480 * before the pte is switched to the new page, and 2481 * "reuse" the old page writing into it while our pte 2482 * here still points into it and can be read by other 2483 * threads. 2484 * 2485 * The critical issue is to order this 2486 * page_remove_rmap with the ptp_clear_flush above. 2487 * Those stores are ordered by (if nothing else,) 2488 * the barrier present in the atomic_add_negative 2489 * in page_remove_rmap. 2490 * 2491 * Then the TLB flush in ptep_clear_flush ensures that 2492 * no process can access the old page before the 2493 * decremented mapcount is visible. And the old page 2494 * cannot be reused until after the decremented 2495 * mapcount is visible. So transitively, TLBs to 2496 * old page will be flushed before it can be reused. 2497 */ 2498 page_remove_rmap(old_page); 2499 } 2500 2501 /* Free the old page.. */ 2502 new_page = old_page; 2503 ret |= VM_FAULT_WRITE; 2504 } else 2505 mem_cgroup_uncharge_page(new_page); 2506 2507 if (new_page) 2508 page_cache_release(new_page); 2509unlock: 2510 pte_unmap_unlock(page_table, ptl); 2511 if (old_page) { 2512 /* 2513 * Don't let another task, with possibly unlocked vma, 2514 * keep the mlocked page. 2515 */ 2516 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) { 2517 lock_page(old_page); /* LRU manipulation */ 2518 munlock_vma_page(old_page); 2519 unlock_page(old_page); 2520 } 2521 page_cache_release(old_page); 2522 } 2523 return ret; 2524oom_free_new: 2525 page_cache_release(new_page); 2526oom: 2527 if (old_page) { 2528 if (page_mkwrite) { 2529 unlock_page(old_page); 2530 page_cache_release(old_page); 2531 } 2532 page_cache_release(old_page); 2533 } 2534 return VM_FAULT_OOM; 2535 2536unwritable_page: 2537 page_cache_release(old_page); 2538 return ret; 2539} 2540 2541/* 2542 * Helper functions for unmap_mapping_range(). 2543 * 2544 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 2545 * 2546 * We have to restart searching the prio_tree whenever we drop the lock, 2547 * since the iterator is only valid while the lock is held, and anyway 2548 * a later vma might be split and reinserted earlier while lock dropped. 2549 * 2550 * The list of nonlinear vmas could be handled more efficiently, using 2551 * a placeholder, but handle it in the same way until a need is shown. 2552 * It is important to search the prio_tree before nonlinear list: a vma 2553 * may become nonlinear and be shifted from prio_tree to nonlinear list 2554 * while the lock is dropped; but never shifted from list to prio_tree. 2555 * 2556 * In order to make forward progress despite restarting the search, 2557 * vm_truncate_count is used to mark a vma as now dealt with, so we can 2558 * quickly skip it next time around. Since the prio_tree search only 2559 * shows us those vmas affected by unmapping the range in question, we 2560 * can't efficiently keep all vmas in step with mapping->truncate_count: 2561 * so instead reset them all whenever it wraps back to 0 (then go to 1). 2562 * mapping->truncate_count and vma->vm_truncate_count are protected by 2563 * i_mmap_lock. 2564 * 2565 * In order to make forward progress despite repeatedly restarting some 2566 * large vma, note the restart_addr from unmap_vmas when it breaks out: 2567 * and restart from that address when we reach that vma again. It might 2568 * have been split or merged, shrunk or extended, but never shifted: so 2569 * restart_addr remains valid so long as it remains in the vma's range. 2570 * unmap_mapping_range forces truncate_count to leap over page-aligned 2571 * values so we can save vma's restart_addr in its truncate_count field. 2572 */ 2573#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 2574 2575static void reset_vma_truncate_counts(struct address_space *mapping) 2576{ 2577 struct vm_area_struct *vma; 2578 struct prio_tree_iter iter; 2579 2580 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 2581 vma->vm_truncate_count = 0; 2582 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 2583 vma->vm_truncate_count = 0; 2584} 2585 2586static int unmap_mapping_range_vma(struct vm_area_struct *vma, 2587 unsigned long start_addr, unsigned long end_addr, 2588 struct zap_details *details) 2589{ 2590 unsigned long restart_addr; 2591 int need_break; 2592 2593 /* 2594 * files that support invalidating or truncating portions of the 2595 * file from under mmaped areas must have their ->fault function 2596 * return a locked page (and set VM_FAULT_LOCKED in the return). 2597 * This provides synchronisation against concurrent unmapping here. 2598 */ 2599 2600again: 2601 restart_addr = vma->vm_truncate_count; 2602 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 2603 start_addr = restart_addr; 2604 if (start_addr >= end_addr) { 2605 /* Top of vma has been split off since last time */ 2606 vma->vm_truncate_count = details->truncate_count; 2607 return 0; 2608 } 2609 } 2610 2611 restart_addr = zap_page_range(vma, start_addr, 2612 end_addr - start_addr, details); 2613 need_break = need_resched() || spin_needbreak(details->i_mmap_lock); 2614 2615 if (restart_addr >= end_addr) { 2616 /* We have now completed this vma: mark it so */ 2617 vma->vm_truncate_count = details->truncate_count; 2618 if (!need_break) 2619 return 0; 2620 } else { 2621 /* Note restart_addr in vma's truncate_count field */ 2622 vma->vm_truncate_count = restart_addr; 2623 if (!need_break) 2624 goto again; 2625 } 2626 2627 spin_unlock(details->i_mmap_lock); 2628 cond_resched(); 2629 spin_lock(details->i_mmap_lock); 2630 return -EINTR; 2631} 2632 2633static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 2634 struct zap_details *details) 2635{ 2636 struct vm_area_struct *vma; 2637 struct prio_tree_iter iter; 2638 pgoff_t vba, vea, zba, zea; 2639 2640restart: 2641 vma_prio_tree_foreach(vma, &iter, root, 2642 details->first_index, details->last_index) { 2643 /* Skip quickly over those we have already dealt with */ 2644 if (vma->vm_truncate_count == details->truncate_count) 2645 continue; 2646 2647 vba = vma->vm_pgoff; 2648 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 2649 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2650 zba = details->first_index; 2651 if (zba < vba) 2652 zba = vba; 2653 zea = details->last_index; 2654 if (zea > vea) 2655 zea = vea; 2656 2657 if (unmap_mapping_range_vma(vma, 2658 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2659 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2660 details) < 0) 2661 goto restart; 2662 } 2663} 2664 2665static inline void unmap_mapping_range_list(struct list_head *head, 2666 struct zap_details *details) 2667{ 2668 struct vm_area_struct *vma; 2669 2670 /* 2671 * In nonlinear VMAs there is no correspondence between virtual address 2672 * offset and file offset. So we must perform an exhaustive search 2673 * across *all* the pages in each nonlinear VMA, not just the pages 2674 * whose virtual address lies outside the file truncation point. 2675 */ 2676restart: 2677 list_for_each_entry(vma, head, shared.vm_set.list) { 2678 /* Skip quickly over those we have already dealt with */ 2679 if (vma->vm_truncate_count == details->truncate_count) 2680 continue; 2681 details->nonlinear_vma = vma; 2682 if (unmap_mapping_range_vma(vma, vma->vm_start, 2683 vma->vm_end, details) < 0) 2684 goto restart; 2685 } 2686} 2687 2688/** 2689 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2690 * @mapping: the address space containing mmaps to be unmapped. 2691 * @holebegin: byte in first page to unmap, relative to the start of 2692 * the underlying file. This will be rounded down to a PAGE_SIZE 2693 * boundary. Note that this is different from truncate_pagecache(), which 2694 * must keep the partial page. In contrast, we must get rid of 2695 * partial pages. 2696 * @holelen: size of prospective hole in bytes. This will be rounded 2697 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2698 * end of the file. 2699 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2700 * but 0 when invalidating pagecache, don't throw away private data. 2701 */ 2702void unmap_mapping_range(struct address_space *mapping, 2703 loff_t const holebegin, loff_t const holelen, int even_cows) 2704{ 2705 struct zap_details details; 2706 pgoff_t hba = holebegin >> PAGE_SHIFT; 2707 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2708 2709 /* Check for overflow. */ 2710 if (sizeof(holelen) > sizeof(hlen)) { 2711 long long holeend = 2712 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2713 if (holeend & ~(long long)ULONG_MAX) 2714 hlen = ULONG_MAX - hba + 1; 2715 } 2716 2717 details.check_mapping = even_cows? NULL: mapping; 2718 details.nonlinear_vma = NULL; 2719 details.first_index = hba; 2720 details.last_index = hba + hlen - 1; 2721 if (details.last_index < details.first_index) 2722 details.last_index = ULONG_MAX; 2723 details.i_mmap_lock = &mapping->i_mmap_lock; 2724 2725 mutex_lock(&mapping->unmap_mutex); 2726 spin_lock(&mapping->i_mmap_lock); 2727 2728 /* Protect against endless unmapping loops */ 2729 mapping->truncate_count++; 2730 if (unlikely(is_restart_addr(mapping->truncate_count))) { 2731 if (mapping->truncate_count == 0) 2732 reset_vma_truncate_counts(mapping); 2733 mapping->truncate_count++; 2734 } 2735 details.truncate_count = mapping->truncate_count; 2736 2737 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 2738 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2739 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 2740 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 2741 spin_unlock(&mapping->i_mmap_lock); 2742 mutex_unlock(&mapping->unmap_mutex); 2743} 2744EXPORT_SYMBOL(unmap_mapping_range); 2745 2746int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 2747{ 2748 struct address_space *mapping = inode->i_mapping; 2749 2750 /* 2751 * If the underlying filesystem is not going to provide 2752 * a way to truncate a range of blocks (punch a hole) - 2753 * we should return failure right now. 2754 */ 2755 if (!inode->i_op->truncate_range) 2756 return -ENOSYS; 2757 2758 mutex_lock(&inode->i_mutex); 2759 down_write(&inode->i_alloc_sem); 2760 unmap_mapping_range(mapping, offset, (end - offset), 1); 2761 truncate_inode_pages_range(mapping, offset, end); 2762 unmap_mapping_range(mapping, offset, (end - offset), 1); 2763 inode->i_op->truncate_range(inode, offset, end); 2764 up_write(&inode->i_alloc_sem); 2765 mutex_unlock(&inode->i_mutex); 2766 2767 return 0; 2768} 2769 2770/* 2771 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2772 * but allow concurrent faults), and pte mapped but not yet locked. 2773 * We return with mmap_sem still held, but pte unmapped and unlocked. 2774 */ 2775static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2776 unsigned long address, pte_t *page_table, pmd_t *pmd, 2777 unsigned int flags, pte_t orig_pte) 2778{ 2779 spinlock_t *ptl; 2780 struct page *page, *swapcache = NULL; 2781 swp_entry_t entry; 2782 pte_t pte; 2783 int locked; 2784 struct mem_cgroup *ptr; 2785 int exclusive = 0; 2786 int ret = 0; 2787 2788 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2789 goto out; 2790 2791 entry = pte_to_swp_entry(orig_pte); 2792 if (unlikely(non_swap_entry(entry))) { 2793 if (is_migration_entry(entry)) { 2794 migration_entry_wait(mm, pmd, address); 2795 } else if (is_hwpoison_entry(entry)) { 2796 ret = VM_FAULT_HWPOISON; 2797 } else { 2798 print_bad_pte(vma, address, orig_pte, NULL); 2799 ret = VM_FAULT_SIGBUS; 2800 } 2801 goto out; 2802 } 2803 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2804 page = lookup_swap_cache(entry); 2805 if (!page) { 2806 grab_swap_token(mm); /* Contend for token _before_ read-in */ 2807 page = swapin_readahead(entry, 2808 GFP_HIGHUSER_MOVABLE, vma, address); 2809 if (!page) { 2810 /* 2811 * Back out if somebody else faulted in this pte 2812 * while we released the pte lock. 2813 */ 2814 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2815 if (likely(pte_same(*page_table, orig_pte))) 2816 ret = VM_FAULT_OOM; 2817 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2818 goto unlock; 2819 } 2820 2821 /* Had to read the page from swap area: Major fault */ 2822 ret = VM_FAULT_MAJOR; 2823 count_vm_event(PGMAJFAULT); 2824 } else if (PageHWPoison(page)) { 2825 /* 2826 * hwpoisoned dirty swapcache pages are kept for killing 2827 * owner processes (which may be unknown at hwpoison time) 2828 */ 2829 ret = VM_FAULT_HWPOISON; 2830 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2831 goto out_release; 2832 } 2833 2834 locked = lock_page_or_retry(page, mm, flags); 2835 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2836 if (!locked) { 2837 ret |= VM_FAULT_RETRY; 2838 goto out_release; 2839 } 2840 2841 /* 2842 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not 2843 * release the swapcache from under us. The page pin, and pte_same 2844 * test below, are not enough to exclude that. Even if it is still 2845 * swapcache, we need to check that the page's swap has not changed. 2846 */ 2847 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val)) 2848 goto out_page; 2849 2850 if (ksm_might_need_to_copy(page, vma, address)) { 2851 swapcache = page; 2852 page = ksm_does_need_to_copy(page, vma, address); 2853 2854 if (unlikely(!page)) { 2855 ret = VM_FAULT_OOM; 2856 page = swapcache; 2857 swapcache = NULL; 2858 goto out_page; 2859 } 2860 } 2861 2862 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { 2863 ret = VM_FAULT_OOM; 2864 goto out_page; 2865 } 2866 2867 /* 2868 * Back out if somebody else already faulted in this pte. 2869 */ 2870 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2871 if (unlikely(!pte_same(*page_table, orig_pte))) 2872 goto out_nomap; 2873 2874 if (unlikely(!PageUptodate(page))) { 2875 ret = VM_FAULT_SIGBUS; 2876 goto out_nomap; 2877 } 2878 2879 /* 2880 * The page isn't present yet, go ahead with the fault. 2881 * 2882 * Be careful about the sequence of operations here. 2883 * To get its accounting right, reuse_swap_page() must be called 2884 * while the page is counted on swap but not yet in mapcount i.e. 2885 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2886 * must be called after the swap_free(), or it will never succeed. 2887 * Because delete_from_swap_page() may be called by reuse_swap_page(), 2888 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry 2889 * in page->private. In this case, a record in swap_cgroup is silently 2890 * discarded at swap_free(). 2891 */ 2892 2893 inc_mm_counter_fast(mm, MM_ANONPAGES); 2894 dec_mm_counter_fast(mm, MM_SWAPENTS); 2895 pte = mk_pte(page, vma->vm_page_prot); 2896 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 2897 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2898 flags &= ~FAULT_FLAG_WRITE; 2899 ret |= VM_FAULT_WRITE; 2900 exclusive = 1; 2901 } 2902 flush_icache_page(vma, page); 2903 set_pte_at(mm, address, page_table, pte); 2904 do_page_add_anon_rmap(page, vma, address, exclusive); 2905 /* It's better to call commit-charge after rmap is established */ 2906 mem_cgroup_commit_charge_swapin(page, ptr); 2907 2908 swap_free(entry); 2909 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 2910 try_to_free_swap(page); 2911 unlock_page(page); 2912 if (swapcache) { 2913 /* 2914 * Hold the lock to avoid the swap entry to be reused 2915 * until we take the PT lock for the pte_same() check 2916 * (to avoid false positives from pte_same). For 2917 * further safety release the lock after the swap_free 2918 * so that the swap count won't change under a 2919 * parallel locked swapcache. 2920 */ 2921 unlock_page(swapcache); 2922 page_cache_release(swapcache); 2923 } 2924 2925 if (flags & FAULT_FLAG_WRITE) { 2926 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 2927 if (ret & VM_FAULT_ERROR) 2928 ret &= VM_FAULT_ERROR; 2929 goto out; 2930 } 2931 2932 /* No need to invalidate - it was non-present before */ 2933 update_mmu_cache(vma, address, page_table); 2934unlock: 2935 pte_unmap_unlock(page_table, ptl); 2936out: 2937 return ret; 2938out_nomap: 2939 mem_cgroup_cancel_charge_swapin(ptr); 2940 pte_unmap_unlock(page_table, ptl); 2941out_page: 2942 unlock_page(page); 2943out_release: 2944 page_cache_release(page); 2945 if (swapcache) { 2946 unlock_page(swapcache); 2947 page_cache_release(swapcache); 2948 } 2949 return ret; 2950} 2951 2952/* 2953 * This is like a special single-page "expand_{down|up}wards()", 2954 * except we must first make sure that 'address{-|+}PAGE_SIZE' 2955 * doesn't hit another vma. 2956 */ 2957static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address) 2958{ 2959 address &= PAGE_MASK; 2960 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) { 2961 struct vm_area_struct *prev = vma->vm_prev; 2962 2963 /* 2964 * Is there a mapping abutting this one below? 2965 * 2966 * That's only ok if it's the same stack mapping 2967 * that has gotten split.. 2968 */ 2969 if (prev && prev->vm_end == address) 2970 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM; 2971 2972 expand_stack(vma, address - PAGE_SIZE); 2973 } 2974 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) { 2975 struct vm_area_struct *next = vma->vm_next; 2976 2977 /* As VM_GROWSDOWN but s/below/above/ */ 2978 if (next && next->vm_start == address + PAGE_SIZE) 2979 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM; 2980 2981 expand_upwards(vma, address + PAGE_SIZE); 2982 } 2983 return 0; 2984} 2985 2986/* 2987 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2988 * but allow concurrent faults), and pte mapped but not yet locked. 2989 * We return with mmap_sem still held, but pte unmapped and unlocked. 2990 */ 2991static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2992 unsigned long address, pte_t *page_table, pmd_t *pmd, 2993 unsigned int flags) 2994{ 2995 struct page *page; 2996 spinlock_t *ptl; 2997 pte_t entry; 2998 2999 pte_unmap(page_table); 3000 3001 /* Check if we need to add a guard page to the stack */ 3002 if (check_stack_guard_page(vma, address) < 0) 3003 return VM_FAULT_SIGBUS; 3004 3005 /* Use the zero-page for reads */ 3006 if (!(flags & FAULT_FLAG_WRITE)) { 3007 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), 3008 vma->vm_page_prot)); 3009 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3010 if (!pte_none(*page_table)) 3011 goto unlock; 3012 goto setpte; 3013 } 3014 3015 /* Allocate our own private page. */ 3016 if (unlikely(anon_vma_prepare(vma))) 3017 goto oom; 3018 page = alloc_zeroed_user_highpage_movable(vma, address); 3019 if (!page) 3020 goto oom; 3021 __SetPageUptodate(page); 3022 3023 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) 3024 goto oom_free_page; 3025 3026 entry = mk_pte(page, vma->vm_page_prot); 3027 if (vma->vm_flags & VM_WRITE) 3028 entry = pte_mkwrite(pte_mkdirty(entry)); 3029 3030 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3031 if (!pte_none(*page_table)) 3032 goto release; 3033 3034 inc_mm_counter_fast(mm, MM_ANONPAGES); 3035 page_add_new_anon_rmap(page, vma, address); 3036setpte: 3037 set_pte_at(mm, address, page_table, entry); 3038 3039 /* No need to invalidate - it was non-present before */ 3040 update_mmu_cache(vma, address, page_table); 3041unlock: 3042 pte_unmap_unlock(page_table, ptl); 3043 return 0; 3044release: 3045 mem_cgroup_uncharge_page(page); 3046 page_cache_release(page); 3047 goto unlock; 3048oom_free_page: 3049 page_cache_release(page); 3050oom: 3051 return VM_FAULT_OOM; 3052} 3053 3054/* 3055 * __do_fault() tries to create a new page mapping. It aggressively 3056 * tries to share with existing pages, but makes a separate copy if 3057 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 3058 * the next page fault. 3059 * 3060 * As this is called only for pages that do not currently exist, we 3061 * do not need to flush old virtual caches or the TLB. 3062 * 3063 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3064 * but allow concurrent faults), and pte neither mapped nor locked. 3065 * We return with mmap_sem still held, but pte unmapped and unlocked. 3066 */ 3067static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3068 unsigned long address, pmd_t *pmd, 3069 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 3070{ 3071 pte_t *page_table; 3072 spinlock_t *ptl; 3073 struct page *page; 3074 pte_t entry; 3075 int anon = 0; 3076 int charged = 0; 3077 struct page *dirty_page = NULL; 3078 struct vm_fault vmf; 3079 int ret; 3080 int page_mkwrite = 0; 3081 3082 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 3083 vmf.pgoff = pgoff; 3084 vmf.flags = flags; 3085 vmf.page = NULL; 3086 3087 ret = vma->vm_ops->fault(vma, &vmf); 3088 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | 3089 VM_FAULT_RETRY))) 3090 return ret; 3091 3092 if (unlikely(PageHWPoison(vmf.page))) { 3093 if (ret & VM_FAULT_LOCKED) 3094 unlock_page(vmf.page); 3095 return VM_FAULT_HWPOISON; 3096 } 3097 3098 /* 3099 * For consistency in subsequent calls, make the faulted page always 3100 * locked. 3101 */ 3102 if (unlikely(!(ret & VM_FAULT_LOCKED))) 3103 lock_page(vmf.page); 3104 else 3105 VM_BUG_ON(!PageLocked(vmf.page)); 3106 3107 /* 3108 * Should we do an early C-O-W break? 3109 */ 3110 page = vmf.page; 3111 if (flags & FAULT_FLAG_WRITE) { 3112 if (!(vma->vm_flags & VM_SHARED)) { 3113 anon = 1; 3114 if (unlikely(anon_vma_prepare(vma))) { 3115 ret = VM_FAULT_OOM; 3116 goto out; 3117 } 3118 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, 3119 vma, address); 3120 if (!page) { 3121 ret = VM_FAULT_OOM; 3122 goto out; 3123 } 3124 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) { 3125 ret = VM_FAULT_OOM; 3126 page_cache_release(page); 3127 goto out; 3128 } 3129 charged = 1; 3130 copy_user_highpage(page, vmf.page, address, vma); 3131 __SetPageUptodate(page); 3132 } else { 3133 /* 3134 * If the page will be shareable, see if the backing 3135 * address space wants to know that the page is about 3136 * to become writable 3137 */ 3138 if (vma->vm_ops->page_mkwrite) { 3139 int tmp; 3140 3141 unlock_page(page); 3142 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 3143 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 3144 if (unlikely(tmp & 3145 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 3146 ret = tmp; 3147 goto unwritable_page; 3148 } 3149 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 3150 lock_page(page); 3151 if (!page->mapping) { 3152 ret = 0; /* retry the fault */ 3153 unlock_page(page); 3154 goto unwritable_page; 3155 } 3156 } else 3157 VM_BUG_ON(!PageLocked(page)); 3158 page_mkwrite = 1; 3159 } 3160 } 3161 3162 } 3163 3164 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 3165 3166 /* 3167 * This silly early PAGE_DIRTY setting removes a race 3168 * due to the bad i386 page protection. But it's valid 3169 * for other architectures too. 3170 * 3171 * Note that if FAULT_FLAG_WRITE is set, we either now have 3172 * an exclusive copy of the page, or this is a shared mapping, 3173 * so we can make it writable and dirty to avoid having to 3174 * handle that later. 3175 */ 3176 /* Only go through if we didn't race with anybody else... */ 3177 if (likely(pte_same(*page_table, orig_pte))) { 3178 flush_icache_page(vma, page); 3179 entry = mk_pte(page, vma->vm_page_prot); 3180 if (flags & FAULT_FLAG_WRITE) 3181 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 3182 if (anon) { 3183 inc_mm_counter_fast(mm, MM_ANONPAGES); 3184 page_add_new_anon_rmap(page, vma, address); 3185 } else { 3186 inc_mm_counter_fast(mm, MM_FILEPAGES); 3187 page_add_file_rmap(page); 3188 if (flags & FAULT_FLAG_WRITE) { 3189 dirty_page = page; 3190 get_page(dirty_page); 3191 } 3192 } 3193 set_pte_at(mm, address, page_table, entry); 3194 3195 /* no need to invalidate: a not-present page won't be cached */ 3196 update_mmu_cache(vma, address, page_table); 3197 } else { 3198 if (charged) 3199 mem_cgroup_uncharge_page(page); 3200 if (anon) 3201 page_cache_release(page); 3202 else 3203 anon = 1; /* no anon but release faulted_page */ 3204 } 3205 3206 pte_unmap_unlock(page_table, ptl); 3207 3208out: 3209 if (dirty_page) { 3210 struct address_space *mapping = page->mapping; 3211 3212 if (set_page_dirty(dirty_page)) 3213 page_mkwrite = 1; 3214 unlock_page(dirty_page); 3215 put_page(dirty_page); 3216 if (page_mkwrite && mapping) { 3217 /* 3218 * Some device drivers do not set page.mapping but still 3219 * dirty their pages 3220 */ 3221 balance_dirty_pages_ratelimited(mapping); 3222 } 3223 3224 /* file_update_time outside page_lock */ 3225 if (vma->vm_file) 3226 file_update_time(vma->vm_file); 3227 } else { 3228 unlock_page(vmf.page); 3229 if (anon) 3230 page_cache_release(vmf.page); 3231 } 3232 3233 return ret; 3234 3235unwritable_page: 3236 page_cache_release(page); 3237 return ret; 3238} 3239 3240static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3241 unsigned long address, pte_t *page_table, pmd_t *pmd, 3242 unsigned int flags, pte_t orig_pte) 3243{ 3244 pgoff_t pgoff = (((address & PAGE_MASK) 3245 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 3246 3247 pte_unmap(page_table); 3248 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3249} 3250 3251/* 3252 * Fault of a previously existing named mapping. Repopulate the pte 3253 * from the encoded file_pte if possible. This enables swappable 3254 * nonlinear vmas. 3255 * 3256 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3257 * but allow concurrent faults), and pte mapped but not yet locked. 3258 * We return with mmap_sem still held, but pte unmapped and unlocked. 3259 */ 3260static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3261 unsigned long address, pte_t *page_table, pmd_t *pmd, 3262 unsigned int flags, pte_t orig_pte) 3263{ 3264 pgoff_t pgoff; 3265 3266 flags |= FAULT_FLAG_NONLINEAR; 3267 3268 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 3269 return 0; 3270 3271 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 3272 /* 3273 * Page table corrupted: show pte and kill process. 3274 */ 3275 print_bad_pte(vma, address, orig_pte, NULL); 3276 return VM_FAULT_SIGBUS; 3277 } 3278 3279 pgoff = pte_to_pgoff(orig_pte); 3280 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 3281} 3282 3283/* 3284 * These routines also need to handle stuff like marking pages dirty 3285 * and/or accessed for architectures that don't do it in hardware (most 3286 * RISC architectures). The early dirtying is also good on the i386. 3287 * 3288 * There is also a hook called "update_mmu_cache()" that architectures 3289 * with external mmu caches can use to update those (ie the Sparc or 3290 * PowerPC hashed page tables that act as extended TLBs). 3291 * 3292 * We enter with non-exclusive mmap_sem (to exclude vma changes, 3293 * but allow concurrent faults), and pte mapped but not yet locked. 3294 * We return with mmap_sem still held, but pte unmapped and unlocked. 3295 */ 3296int handle_pte_fault(struct mm_struct *mm, 3297 struct vm_area_struct *vma, unsigned long address, 3298 pte_t *pte, pmd_t *pmd, unsigned int flags) 3299{ 3300 pte_t entry; 3301 spinlock_t *ptl; 3302 3303 entry = *pte; 3304 if (!pte_present(entry)) { 3305 if (pte_none(entry)) { 3306 if (vma->vm_ops) { 3307 if (likely(vma->vm_ops->fault)) 3308 return do_linear_fault(mm, vma, address, 3309 pte, pmd, flags, entry); 3310 } 3311 return do_anonymous_page(mm, vma, address, 3312 pte, pmd, flags); 3313 } 3314 if (pte_file(entry)) 3315 return do_nonlinear_fault(mm, vma, address, 3316 pte, pmd, flags, entry); 3317 return do_swap_page(mm, vma, address, 3318 pte, pmd, flags, entry); 3319 } 3320 3321 ptl = pte_lockptr(mm, pmd); 3322 spin_lock(ptl); 3323 if (unlikely(!pte_same(*pte, entry))) 3324 goto unlock; 3325 if (flags & FAULT_FLAG_WRITE) { 3326 if (!pte_write(entry)) 3327 return do_wp_page(mm, vma, address, 3328 pte, pmd, ptl, entry); 3329 entry = pte_mkdirty(entry); 3330 } 3331 entry = pte_mkyoung(entry); 3332 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 3333 update_mmu_cache(vma, address, pte); 3334 } else { 3335 /* 3336 * This is needed only for protection faults but the arch code 3337 * is not yet telling us if this is a protection fault or not. 3338 * This still avoids useless tlb flushes for .text page faults 3339 * with threads. 3340 */ 3341 if (flags & FAULT_FLAG_WRITE) 3342 flush_tlb_fix_spurious_fault(vma, address); 3343 } 3344unlock: 3345 pte_unmap_unlock(pte, ptl); 3346 return 0; 3347} 3348 3349/* 3350 * By the time we get here, we already hold the mm semaphore 3351 */ 3352int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3353 unsigned long address, unsigned int flags) 3354{ 3355 pgd_t *pgd; 3356 pud_t *pud; 3357 pmd_t *pmd; 3358 pte_t *pte; 3359 3360 __set_current_state(TASK_RUNNING); 3361 3362 count_vm_event(PGFAULT); 3363 3364 /* do counter updates before entering really critical section. */ 3365 check_sync_rss_stat(current); 3366 3367 if (unlikely(is_vm_hugetlb_page(vma))) 3368 return hugetlb_fault(mm, vma, address, flags); 3369 3370 pgd = pgd_offset(mm, address); 3371 pud = pud_alloc(mm, pgd, address); 3372 if (!pud) 3373 return VM_FAULT_OOM; 3374 pmd = pmd_alloc(mm, pud, address); 3375 if (!pmd) 3376 return VM_FAULT_OOM; 3377 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) { 3378 if (!vma->vm_ops) 3379 return do_huge_pmd_anonymous_page(mm, vma, address, 3380 pmd, flags); 3381 } else { 3382 pmd_t orig_pmd = *pmd; 3383 barrier(); 3384 if (pmd_trans_huge(orig_pmd)) { 3385 if (flags & FAULT_FLAG_WRITE && 3386 !pmd_write(orig_pmd) && 3387 !pmd_trans_splitting(orig_pmd)) 3388 return do_huge_pmd_wp_page(mm, vma, address, 3389 pmd, orig_pmd); 3390 return 0; 3391 } 3392 } 3393 3394 /* 3395 * Use __pte_alloc instead of pte_alloc_map, because we can't 3396 * run pte_offset_map on the pmd, if an huge pmd could 3397 * materialize from under us from a different thread. 3398 */ 3399 if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address)) 3400 return VM_FAULT_OOM; 3401 /* if an huge pmd materialized from under us just retry later */ 3402 if (unlikely(pmd_trans_huge(*pmd))) 3403 return 0; 3404 /* 3405 * A regular pmd is established and it can't morph into a huge pmd 3406 * from under us anymore at this point because we hold the mmap_sem 3407 * read mode and khugepaged takes it in write mode. So now it's 3408 * safe to run pte_offset_map(). 3409 */ 3410 pte = pte_offset_map(pmd, address); 3411 3412 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 3413} 3414 3415#ifndef __PAGETABLE_PUD_FOLDED 3416/* 3417 * Allocate page upper directory. 3418 * We've already handled the fast-path in-line. 3419 */ 3420int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3421{ 3422 pud_t *new = pud_alloc_one(mm, address); 3423 if (!new) 3424 return -ENOMEM; 3425 3426 smp_wmb(); /* See comment in __pte_alloc */ 3427 3428 spin_lock(&mm->page_table_lock); 3429 if (pgd_present(*pgd)) /* Another has populated it */ 3430 pud_free(mm, new); 3431 else 3432 pgd_populate(mm, pgd, new); 3433 spin_unlock(&mm->page_table_lock); 3434 return 0; 3435} 3436#endif /* __PAGETABLE_PUD_FOLDED */ 3437 3438#ifndef __PAGETABLE_PMD_FOLDED 3439/* 3440 * Allocate page middle directory. 3441 * We've already handled the fast-path in-line. 3442 */ 3443int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 3444{ 3445 pmd_t *new = pmd_alloc_one(mm, address); 3446 if (!new) 3447 return -ENOMEM; 3448 3449 smp_wmb(); /* See comment in __pte_alloc */ 3450 3451 spin_lock(&mm->page_table_lock); 3452#ifndef __ARCH_HAS_4LEVEL_HACK 3453 if (pud_present(*pud)) /* Another has populated it */ 3454 pmd_free(mm, new); 3455 else 3456 pud_populate(mm, pud, new); 3457#else 3458 if (pgd_present(*pud)) /* Another has populated it */ 3459 pmd_free(mm, new); 3460 else 3461 pgd_populate(mm, pud, new); 3462#endif /* __ARCH_HAS_4LEVEL_HACK */ 3463 spin_unlock(&mm->page_table_lock); 3464 return 0; 3465} 3466#endif /* __PAGETABLE_PMD_FOLDED */ 3467 3468int make_pages_present(unsigned long addr, unsigned long end) 3469{ 3470 int ret, len, write; 3471 struct vm_area_struct * vma; 3472 3473 vma = find_vma(current->mm, addr); 3474 if (!vma) 3475 return -ENOMEM; 3476 /* 3477 * We want to touch writable mappings with a write fault in order 3478 * to break COW, except for shared mappings because these don't COW 3479 * and we would not want to dirty them for nothing. 3480 */ 3481 write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE; 3482 BUG_ON(addr >= end); 3483 BUG_ON(end > vma->vm_end); 3484 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; 3485 ret = get_user_pages(current, current->mm, addr, 3486 len, write, 0, NULL, NULL); 3487 if (ret < 0) 3488 return ret; 3489 return ret == len ? 0 : -EFAULT; 3490} 3491 3492#if !defined(__HAVE_ARCH_GATE_AREA) 3493 3494#if defined(AT_SYSINFO_EHDR) 3495static struct vm_area_struct gate_vma; 3496 3497static int __init gate_vma_init(void) 3498{ 3499 gate_vma.vm_mm = NULL; 3500 gate_vma.vm_start = FIXADDR_USER_START; 3501 gate_vma.vm_end = FIXADDR_USER_END; 3502 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 3503 gate_vma.vm_page_prot = __P101; 3504 /* 3505 * Make sure the vDSO gets into every core dump. 3506 * Dumping its contents makes post-mortem fully interpretable later 3507 * without matching up the same kernel and hardware config to see 3508 * what PC values meant. 3509 */ 3510 gate_vma.vm_flags |= VM_ALWAYSDUMP; 3511 return 0; 3512} 3513__initcall(gate_vma_init); 3514#endif 3515 3516struct vm_area_struct *get_gate_vma(struct mm_struct *mm) 3517{ 3518#ifdef AT_SYSINFO_EHDR 3519 return &gate_vma; 3520#else 3521 return NULL; 3522#endif 3523} 3524 3525int in_gate_area_no_mm(unsigned long addr) 3526{ 3527#ifdef AT_SYSINFO_EHDR 3528 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 3529 return 1; 3530#endif 3531 return 0; 3532} 3533 3534#endif /* __HAVE_ARCH_GATE_AREA */ 3535 3536static int __follow_pte(struct mm_struct *mm, unsigned long address, 3537 pte_t **ptepp, spinlock_t **ptlp) 3538{ 3539 pgd_t *pgd; 3540 pud_t *pud; 3541 pmd_t *pmd; 3542 pte_t *ptep; 3543 3544 pgd = pgd_offset(mm, address); 3545 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 3546 goto out; 3547 3548 pud = pud_offset(pgd, address); 3549 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 3550 goto out; 3551 3552 pmd = pmd_offset(pud, address); 3553 VM_BUG_ON(pmd_trans_huge(*pmd)); 3554 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 3555 goto out; 3556 3557 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 3558 if (pmd_huge(*pmd)) 3559 goto out; 3560 3561 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 3562 if (!ptep) 3563 goto out; 3564 if (!pte_present(*ptep)) 3565 goto unlock; 3566 *ptepp = ptep; 3567 return 0; 3568unlock: 3569 pte_unmap_unlock(ptep, *ptlp); 3570out: 3571 return -EINVAL; 3572} 3573 3574static inline int follow_pte(struct mm_struct *mm, unsigned long address, 3575 pte_t **ptepp, spinlock_t **ptlp) 3576{ 3577 int res; 3578 3579 /* (void) is needed to make gcc happy */ 3580 (void) __cond_lock(*ptlp, 3581 !(res = __follow_pte(mm, address, ptepp, ptlp))); 3582 return res; 3583} 3584 3585/** 3586 * follow_pfn - look up PFN at a user virtual address 3587 * @vma: memory mapping 3588 * @address: user virtual address 3589 * @pfn: location to store found PFN 3590 * 3591 * Only IO mappings and raw PFN mappings are allowed. 3592 * 3593 * Returns zero and the pfn at @pfn on success, -ve otherwise. 3594 */ 3595int follow_pfn(struct vm_area_struct *vma, unsigned long address, 3596 unsigned long *pfn) 3597{ 3598 int ret = -EINVAL; 3599 spinlock_t *ptl; 3600 pte_t *ptep; 3601 3602 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3603 return ret; 3604 3605 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 3606 if (ret) 3607 return ret; 3608 *pfn = pte_pfn(*ptep); 3609 pte_unmap_unlock(ptep, ptl); 3610 return 0; 3611} 3612EXPORT_SYMBOL(follow_pfn); 3613 3614#ifdef CONFIG_HAVE_IOREMAP_PROT 3615int follow_phys(struct vm_area_struct *vma, 3616 unsigned long address, unsigned int flags, 3617 unsigned long *prot, resource_size_t *phys) 3618{ 3619 int ret = -EINVAL; 3620 pte_t *ptep, pte; 3621 spinlock_t *ptl; 3622 3623 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3624 goto out; 3625 3626 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 3627 goto out; 3628 pte = *ptep; 3629 3630 if ((flags & FOLL_WRITE) && !pte_write(pte)) 3631 goto unlock; 3632 3633 *prot = pgprot_val(pte_pgprot(pte)); 3634 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 3635 3636 ret = 0; 3637unlock: 3638 pte_unmap_unlock(ptep, ptl); 3639out: 3640 return ret; 3641} 3642 3643int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 3644 void *buf, int len, int write) 3645{ 3646 resource_size_t phys_addr; 3647 unsigned long prot = 0; 3648 void __iomem *maddr; 3649 int offset = addr & (PAGE_SIZE-1); 3650 3651 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 3652 return -EINVAL; 3653 3654 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 3655 if (write) 3656 memcpy_toio(maddr + offset, buf, len); 3657 else 3658 memcpy_fromio(buf, maddr + offset, len); 3659 iounmap(maddr); 3660 3661 return len; 3662} 3663#endif 3664 3665/* 3666 * Access another process' address space as given in mm. If non-NULL, use the 3667 * given task for page fault accounting. 3668 */ 3669static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 3670 unsigned long addr, void *buf, int len, int write) 3671{ 3672 struct vm_area_struct *vma; 3673 void *old_buf = buf; 3674 3675 down_read(&mm->mmap_sem); 3676 /* ignore errors, just check how much was successfully transferred */ 3677 while (len) { 3678 int bytes, ret, offset; 3679 void *maddr; 3680 struct page *page = NULL; 3681 3682 ret = get_user_pages(tsk, mm, addr, 1, 3683 write, 1, &page, &vma); 3684 if (ret <= 0) { 3685 /* 3686 * Check if this is a VM_IO | VM_PFNMAP VMA, which 3687 * we can access using slightly different code. 3688 */ 3689#ifdef CONFIG_HAVE_IOREMAP_PROT 3690 vma = find_vma(mm, addr); 3691 if (!vma || vma->vm_start > addr) 3692 break; 3693 if (vma->vm_ops && vma->vm_ops->access) 3694 ret = vma->vm_ops->access(vma, addr, buf, 3695 len, write); 3696 if (ret <= 0) 3697#endif 3698 break; 3699 bytes = ret; 3700 } else { 3701 bytes = len; 3702 offset = addr & (PAGE_SIZE-1); 3703 if (bytes > PAGE_SIZE-offset) 3704 bytes = PAGE_SIZE-offset; 3705 3706 maddr = kmap(page); 3707 if (write) { 3708 copy_to_user_page(vma, page, addr, 3709 maddr + offset, buf, bytes); 3710 set_page_dirty_lock(page); 3711 } else { 3712 copy_from_user_page(vma, page, addr, 3713 buf, maddr + offset, bytes); 3714 } 3715 kunmap(page); 3716 page_cache_release(page); 3717 } 3718 len -= bytes; 3719 buf += bytes; 3720 addr += bytes; 3721 } 3722 up_read(&mm->mmap_sem); 3723 3724 return buf - old_buf; 3725} 3726 3727/** 3728 * access_remote_vm - access another process' address space 3729 * @mm: the mm_struct of the target address space 3730 * @addr: start address to access 3731 * @buf: source or destination buffer 3732 * @len: number of bytes to transfer 3733 * @write: whether the access is a write 3734 * 3735 * The caller must hold a reference on @mm. 3736 */ 3737int access_remote_vm(struct mm_struct *mm, unsigned long addr, 3738 void *buf, int len, int write) 3739{ 3740 return __access_remote_vm(NULL, mm, addr, buf, len, write); 3741} 3742 3743/* 3744 * Access another process' address space. 3745 * Source/target buffer must be kernel space, 3746 * Do not walk the page table directly, use get_user_pages 3747 */ 3748int access_process_vm(struct task_struct *tsk, unsigned long addr, 3749 void *buf, int len, int write) 3750{ 3751 struct mm_struct *mm; 3752 int ret; 3753 3754 mm = get_task_mm(tsk); 3755 if (!mm) 3756 return 0; 3757 3758 ret = __access_remote_vm(tsk, mm, addr, buf, len, write); 3759 mmput(mm); 3760 3761 return ret; 3762} 3763 3764/* 3765 * Print the name of a VMA. 3766 */ 3767void print_vma_addr(char *prefix, unsigned long ip) 3768{ 3769 struct mm_struct *mm = current->mm; 3770 struct vm_area_struct *vma; 3771 3772 /* 3773 * Do not print if we are in atomic 3774 * contexts (in exception stacks, etc.): 3775 */ 3776 if (preempt_count()) 3777 return; 3778 3779 down_read(&mm->mmap_sem); 3780 vma = find_vma(mm, ip); 3781 if (vma && vma->vm_file) { 3782 struct file *f = vma->vm_file; 3783 char *buf = (char *)__get_free_page(GFP_KERNEL); 3784 if (buf) { 3785 char *p, *s; 3786 3787 p = d_path(&f->f_path, buf, PAGE_SIZE); 3788 if (IS_ERR(p)) 3789 p = "?"; 3790 s = strrchr(p, '/'); 3791 if (s) 3792 p = s+1; 3793 printk("%s%s[%lx+%lx]", prefix, p, 3794 vma->vm_start, 3795 vma->vm_end - vma->vm_start); 3796 free_page((unsigned long)buf); 3797 } 3798 } 3799 up_read(¤t->mm->mmap_sem); 3800} 3801 3802#ifdef CONFIG_PROVE_LOCKING 3803void might_fault(void) 3804{ 3805 /* 3806 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 3807 * holding the mmap_sem, this is safe because kernel memory doesn't 3808 * get paged out, therefore we'll never actually fault, and the 3809 * below annotations will generate false positives. 3810 */ 3811 if (segment_eq(get_fs(), KERNEL_DS)) 3812 return; 3813 3814 might_sleep(); 3815 /* 3816 * it would be nicer only to annotate paths which are not under 3817 * pagefault_disable, however that requires a larger audit and 3818 * providing helpers like get_user_atomic. 3819 */ 3820 if (!in_atomic() && current->mm) 3821 might_lock_read(¤t->mm->mmap_sem); 3822} 3823EXPORT_SYMBOL(might_fault); 3824#endif 3825 3826#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS) 3827static void clear_gigantic_page(struct page *page, 3828 unsigned long addr, 3829 unsigned int pages_per_huge_page) 3830{ 3831 int i; 3832 struct page *p = page; 3833 3834 might_sleep(); 3835 for (i = 0; i < pages_per_huge_page; 3836 i++, p = mem_map_next(p, page, i)) { 3837 cond_resched(); 3838 clear_user_highpage(p, addr + i * PAGE_SIZE); 3839 } 3840} 3841void clear_huge_page(struct page *page, 3842 unsigned long addr, unsigned int pages_per_huge_page) 3843{ 3844 int i; 3845 3846 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 3847 clear_gigantic_page(page, addr, pages_per_huge_page); 3848 return; 3849 } 3850 3851 might_sleep(); 3852 for (i = 0; i < pages_per_huge_page; i++) { 3853 cond_resched(); 3854 clear_user_highpage(page + i, addr + i * PAGE_SIZE); 3855 } 3856} 3857 3858static void copy_user_gigantic_page(struct page *dst, struct page *src, 3859 unsigned long addr, 3860 struct vm_area_struct *vma, 3861 unsigned int pages_per_huge_page) 3862{ 3863 int i; 3864 struct page *dst_base = dst; 3865 struct page *src_base = src; 3866 3867 for (i = 0; i < pages_per_huge_page; ) { 3868 cond_resched(); 3869 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma); 3870 3871 i++; 3872 dst = mem_map_next(dst, dst_base, i); 3873 src = mem_map_next(src, src_base, i); 3874 } 3875} 3876 3877void copy_user_huge_page(struct page *dst, struct page *src, 3878 unsigned long addr, struct vm_area_struct *vma, 3879 unsigned int pages_per_huge_page) 3880{ 3881 int i; 3882 3883 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) { 3884 copy_user_gigantic_page(dst, src, addr, vma, 3885 pages_per_huge_page); 3886 return; 3887 } 3888 3889 might_sleep(); 3890 for (i = 0; i < pages_per_huge_page; i++) { 3891 cond_resched(); 3892 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma); 3893 } 3894} 3895#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ 3896