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