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/rmap.h> 49 #include <linux/module.h> 50 #include <linux/delayacct.h> 51 #include <linux/init.h> 52 #include <linux/writeback.h> 53 #include <linux/memcontrol.h> 54 55 #include <asm/pgalloc.h> 56 #include <asm/uaccess.h> 57 #include <asm/tlb.h> 58 #include <asm/tlbflush.h> 59 #include <asm/pgtable.h> 60 61 #include <linux/swapops.h> 62 #include <linux/elf.h> 63 64 #ifndef CONFIG_NEED_MULTIPLE_NODES 65 /* use the per-pgdat data instead for discontigmem - mbligh */ 66 unsigned long max_mapnr; 67 struct page *mem_map; 68 69 EXPORT_SYMBOL(max_mapnr); 70 EXPORT_SYMBOL(mem_map); 71 #endif 72 73 unsigned long num_physpages; 74 /* 75 * A number of key systems in x86 including ioremap() rely on the assumption 76 * that high_memory defines the upper bound on direct map memory, then end 77 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 78 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 79 * and ZONE_HIGHMEM. 80 */ 81 void * high_memory; 82 83 EXPORT_SYMBOL(num_physpages); 84 EXPORT_SYMBOL(high_memory); 85 86 /* 87 * Randomize the address space (stacks, mmaps, brk, etc.). 88 * 89 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 90 * as ancient (libc5 based) binaries can segfault. ) 91 */ 92 int randomize_va_space __read_mostly = 93 #ifdef CONFIG_COMPAT_BRK 94 1; 95 #else 96 2; 97 #endif 98 99 static int __init disable_randmaps(char *s) 100 { 101 randomize_va_space = 0; 102 return 1; 103 } 104 __setup("norandmaps", disable_randmaps); 105 106 107 /* 108 * If a p?d_bad entry is found while walking page tables, report 109 * the error, before resetting entry to p?d_none. Usually (but 110 * very seldom) called out from the p?d_none_or_clear_bad macros. 111 */ 112 113 void pgd_clear_bad(pgd_t *pgd) 114 { 115 pgd_ERROR(*pgd); 116 pgd_clear(pgd); 117 } 118 119 void pud_clear_bad(pud_t *pud) 120 { 121 pud_ERROR(*pud); 122 pud_clear(pud); 123 } 124 125 void pmd_clear_bad(pmd_t *pmd) 126 { 127 pmd_ERROR(*pmd); 128 pmd_clear(pmd); 129 } 130 131 /* 132 * Note: this doesn't free the actual pages themselves. That 133 * has been handled earlier when unmapping all the memory regions. 134 */ 135 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd) 136 { 137 pgtable_t token = pmd_pgtable(*pmd); 138 pmd_clear(pmd); 139 pte_free_tlb(tlb, token); 140 tlb->mm->nr_ptes--; 141 } 142 143 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 144 unsigned long addr, unsigned long end, 145 unsigned long floor, unsigned long ceiling) 146 { 147 pmd_t *pmd; 148 unsigned long next; 149 unsigned long start; 150 151 start = addr; 152 pmd = pmd_offset(pud, addr); 153 do { 154 next = pmd_addr_end(addr, end); 155 if (pmd_none_or_clear_bad(pmd)) 156 continue; 157 free_pte_range(tlb, pmd); 158 } while (pmd++, addr = next, addr != end); 159 160 start &= PUD_MASK; 161 if (start < floor) 162 return; 163 if (ceiling) { 164 ceiling &= PUD_MASK; 165 if (!ceiling) 166 return; 167 } 168 if (end - 1 > ceiling - 1) 169 return; 170 171 pmd = pmd_offset(pud, start); 172 pud_clear(pud); 173 pmd_free_tlb(tlb, pmd); 174 } 175 176 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 177 unsigned long addr, unsigned long end, 178 unsigned long floor, unsigned long ceiling) 179 { 180 pud_t *pud; 181 unsigned long next; 182 unsigned long start; 183 184 start = addr; 185 pud = pud_offset(pgd, addr); 186 do { 187 next = pud_addr_end(addr, end); 188 if (pud_none_or_clear_bad(pud)) 189 continue; 190 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 191 } while (pud++, addr = next, addr != end); 192 193 start &= PGDIR_MASK; 194 if (start < floor) 195 return; 196 if (ceiling) { 197 ceiling &= PGDIR_MASK; 198 if (!ceiling) 199 return; 200 } 201 if (end - 1 > ceiling - 1) 202 return; 203 204 pud = pud_offset(pgd, start); 205 pgd_clear(pgd); 206 pud_free_tlb(tlb, pud); 207 } 208 209 /* 210 * This function frees user-level page tables of a process. 211 * 212 * Must be called with pagetable lock held. 213 */ 214 void free_pgd_range(struct mmu_gather **tlb, 215 unsigned long addr, unsigned long end, 216 unsigned long floor, unsigned long ceiling) 217 { 218 pgd_t *pgd; 219 unsigned long next; 220 unsigned long start; 221 222 /* 223 * The next few lines have given us lots of grief... 224 * 225 * Why are we testing PMD* at this top level? Because often 226 * there will be no work to do at all, and we'd prefer not to 227 * go all the way down to the bottom just to discover that. 228 * 229 * Why all these "- 1"s? Because 0 represents both the bottom 230 * of the address space and the top of it (using -1 for the 231 * top wouldn't help much: the masks would do the wrong thing). 232 * The rule is that addr 0 and floor 0 refer to the bottom of 233 * the address space, but end 0 and ceiling 0 refer to the top 234 * Comparisons need to use "end - 1" and "ceiling - 1" (though 235 * that end 0 case should be mythical). 236 * 237 * Wherever addr is brought up or ceiling brought down, we must 238 * be careful to reject "the opposite 0" before it confuses the 239 * subsequent tests. But what about where end is brought down 240 * by PMD_SIZE below? no, end can't go down to 0 there. 241 * 242 * Whereas we round start (addr) and ceiling down, by different 243 * masks at different levels, in order to test whether a table 244 * now has no other vmas using it, so can be freed, we don't 245 * bother to round floor or end up - the tests don't need that. 246 */ 247 248 addr &= PMD_MASK; 249 if (addr < floor) { 250 addr += PMD_SIZE; 251 if (!addr) 252 return; 253 } 254 if (ceiling) { 255 ceiling &= PMD_MASK; 256 if (!ceiling) 257 return; 258 } 259 if (end - 1 > ceiling - 1) 260 end -= PMD_SIZE; 261 if (addr > end - 1) 262 return; 263 264 start = addr; 265 pgd = pgd_offset((*tlb)->mm, addr); 266 do { 267 next = pgd_addr_end(addr, end); 268 if (pgd_none_or_clear_bad(pgd)) 269 continue; 270 free_pud_range(*tlb, pgd, addr, next, floor, ceiling); 271 } while (pgd++, addr = next, addr != end); 272 } 273 274 void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma, 275 unsigned long floor, unsigned long ceiling) 276 { 277 while (vma) { 278 struct vm_area_struct *next = vma->vm_next; 279 unsigned long addr = vma->vm_start; 280 281 /* 282 * Hide vma from rmap and vmtruncate before freeing pgtables 283 */ 284 anon_vma_unlink(vma); 285 unlink_file_vma(vma); 286 287 if (is_vm_hugetlb_page(vma)) { 288 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 289 floor, next? next->vm_start: ceiling); 290 } else { 291 /* 292 * Optimization: gather nearby vmas into one call down 293 */ 294 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 295 && !is_vm_hugetlb_page(next)) { 296 vma = next; 297 next = vma->vm_next; 298 anon_vma_unlink(vma); 299 unlink_file_vma(vma); 300 } 301 free_pgd_range(tlb, addr, vma->vm_end, 302 floor, next? next->vm_start: ceiling); 303 } 304 vma = next; 305 } 306 } 307 308 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 309 { 310 pgtable_t new = pte_alloc_one(mm, address); 311 if (!new) 312 return -ENOMEM; 313 314 spin_lock(&mm->page_table_lock); 315 if (!pmd_present(*pmd)) { /* Has another populated it ? */ 316 mm->nr_ptes++; 317 pmd_populate(mm, pmd, new); 318 new = NULL; 319 } 320 spin_unlock(&mm->page_table_lock); 321 if (new) 322 pte_free(mm, new); 323 return 0; 324 } 325 326 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 327 { 328 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 329 if (!new) 330 return -ENOMEM; 331 332 spin_lock(&init_mm.page_table_lock); 333 if (!pmd_present(*pmd)) { /* Has another populated it ? */ 334 pmd_populate_kernel(&init_mm, pmd, new); 335 new = NULL; 336 } 337 spin_unlock(&init_mm.page_table_lock); 338 if (new) 339 pte_free_kernel(&init_mm, new); 340 return 0; 341 } 342 343 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) 344 { 345 if (file_rss) 346 add_mm_counter(mm, file_rss, file_rss); 347 if (anon_rss) 348 add_mm_counter(mm, anon_rss, anon_rss); 349 } 350 351 /* 352 * This function is called to print an error when a bad pte 353 * is found. For example, we might have a PFN-mapped pte in 354 * a region that doesn't allow it. 355 * 356 * The calling function must still handle the error. 357 */ 358 void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr) 359 { 360 printk(KERN_ERR "Bad pte = %08llx, process = %s, " 361 "vm_flags = %lx, vaddr = %lx\n", 362 (long long)pte_val(pte), 363 (vma->vm_mm == current->mm ? current->comm : "???"), 364 vma->vm_flags, vaddr); 365 dump_stack(); 366 } 367 368 static inline int is_cow_mapping(unsigned int flags) 369 { 370 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 371 } 372 373 /* 374 * This function gets the "struct page" associated with a pte. 375 * 376 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping 377 * will have each page table entry just pointing to a raw page frame 378 * number, and as far as the VM layer is concerned, those do not have 379 * pages associated with them - even if the PFN might point to memory 380 * that otherwise is perfectly fine and has a "struct page". 381 * 382 * The way we recognize those mappings is through the rules set up 383 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set, 384 * and the vm_pgoff will point to the first PFN mapped: thus every 385 * page that is a raw mapping will always honor the rule 386 * 387 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 388 * 389 * and if that isn't true, the page has been COW'ed (in which case it 390 * _does_ have a "struct page" associated with it even if it is in a 391 * VM_PFNMAP range). 392 */ 393 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte) 394 { 395 unsigned long pfn = pte_pfn(pte); 396 397 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 398 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT; 399 if (pfn == vma->vm_pgoff + off) 400 return NULL; 401 if (!is_cow_mapping(vma->vm_flags)) 402 return NULL; 403 } 404 405 #ifdef CONFIG_DEBUG_VM 406 /* 407 * Add some anal sanity checks for now. Eventually, 408 * we should just do "return pfn_to_page(pfn)", but 409 * in the meantime we check that we get a valid pfn, 410 * and that the resulting page looks ok. 411 */ 412 if (unlikely(!pfn_valid(pfn))) { 413 print_bad_pte(vma, pte, addr); 414 return NULL; 415 } 416 #endif 417 418 /* 419 * NOTE! We still have PageReserved() pages in the page 420 * tables. 421 * 422 * The PAGE_ZERO() pages and various VDSO mappings can 423 * cause them to exist. 424 */ 425 return pfn_to_page(pfn); 426 } 427 428 /* 429 * copy one vm_area from one task to the other. Assumes the page tables 430 * already present in the new task to be cleared in the whole range 431 * covered by this vma. 432 */ 433 434 static inline void 435 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 436 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 437 unsigned long addr, int *rss) 438 { 439 unsigned long vm_flags = vma->vm_flags; 440 pte_t pte = *src_pte; 441 struct page *page; 442 443 /* pte contains position in swap or file, so copy. */ 444 if (unlikely(!pte_present(pte))) { 445 if (!pte_file(pte)) { 446 swp_entry_t entry = pte_to_swp_entry(pte); 447 448 swap_duplicate(entry); 449 /* make sure dst_mm is on swapoff's mmlist. */ 450 if (unlikely(list_empty(&dst_mm->mmlist))) { 451 spin_lock(&mmlist_lock); 452 if (list_empty(&dst_mm->mmlist)) 453 list_add(&dst_mm->mmlist, 454 &src_mm->mmlist); 455 spin_unlock(&mmlist_lock); 456 } 457 if (is_write_migration_entry(entry) && 458 is_cow_mapping(vm_flags)) { 459 /* 460 * COW mappings require pages in both parent 461 * and child to be set to read. 462 */ 463 make_migration_entry_read(&entry); 464 pte = swp_entry_to_pte(entry); 465 set_pte_at(src_mm, addr, src_pte, pte); 466 } 467 } 468 goto out_set_pte; 469 } 470 471 /* 472 * If it's a COW mapping, write protect it both 473 * in the parent and the child 474 */ 475 if (is_cow_mapping(vm_flags)) { 476 ptep_set_wrprotect(src_mm, addr, src_pte); 477 pte = pte_wrprotect(pte); 478 } 479 480 /* 481 * If it's a shared mapping, mark it clean in 482 * the child 483 */ 484 if (vm_flags & VM_SHARED) 485 pte = pte_mkclean(pte); 486 pte = pte_mkold(pte); 487 488 page = vm_normal_page(vma, addr, pte); 489 if (page) { 490 get_page(page); 491 page_dup_rmap(page, vma, addr); 492 rss[!!PageAnon(page)]++; 493 } 494 495 out_set_pte: 496 set_pte_at(dst_mm, addr, dst_pte, pte); 497 } 498 499 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 500 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 501 unsigned long addr, unsigned long end) 502 { 503 pte_t *src_pte, *dst_pte; 504 spinlock_t *src_ptl, *dst_ptl; 505 int progress = 0; 506 int rss[2]; 507 508 again: 509 rss[1] = rss[0] = 0; 510 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 511 if (!dst_pte) 512 return -ENOMEM; 513 src_pte = pte_offset_map_nested(src_pmd, addr); 514 src_ptl = pte_lockptr(src_mm, src_pmd); 515 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 516 arch_enter_lazy_mmu_mode(); 517 518 do { 519 /* 520 * We are holding two locks at this point - either of them 521 * could generate latencies in another task on another CPU. 522 */ 523 if (progress >= 32) { 524 progress = 0; 525 if (need_resched() || 526 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 527 break; 528 } 529 if (pte_none(*src_pte)) { 530 progress++; 531 continue; 532 } 533 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 534 progress += 8; 535 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 536 537 arch_leave_lazy_mmu_mode(); 538 spin_unlock(src_ptl); 539 pte_unmap_nested(src_pte - 1); 540 add_mm_rss(dst_mm, rss[0], rss[1]); 541 pte_unmap_unlock(dst_pte - 1, dst_ptl); 542 cond_resched(); 543 if (addr != end) 544 goto again; 545 return 0; 546 } 547 548 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 549 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 550 unsigned long addr, unsigned long end) 551 { 552 pmd_t *src_pmd, *dst_pmd; 553 unsigned long next; 554 555 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 556 if (!dst_pmd) 557 return -ENOMEM; 558 src_pmd = pmd_offset(src_pud, addr); 559 do { 560 next = pmd_addr_end(addr, end); 561 if (pmd_none_or_clear_bad(src_pmd)) 562 continue; 563 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 564 vma, addr, next)) 565 return -ENOMEM; 566 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 567 return 0; 568 } 569 570 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 571 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 572 unsigned long addr, unsigned long end) 573 { 574 pud_t *src_pud, *dst_pud; 575 unsigned long next; 576 577 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 578 if (!dst_pud) 579 return -ENOMEM; 580 src_pud = pud_offset(src_pgd, addr); 581 do { 582 next = pud_addr_end(addr, end); 583 if (pud_none_or_clear_bad(src_pud)) 584 continue; 585 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 586 vma, addr, next)) 587 return -ENOMEM; 588 } while (dst_pud++, src_pud++, addr = next, addr != end); 589 return 0; 590 } 591 592 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 593 struct vm_area_struct *vma) 594 { 595 pgd_t *src_pgd, *dst_pgd; 596 unsigned long next; 597 unsigned long addr = vma->vm_start; 598 unsigned long end = vma->vm_end; 599 600 /* 601 * Don't copy ptes where a page fault will fill them correctly. 602 * Fork becomes much lighter when there are big shared or private 603 * readonly mappings. The tradeoff is that copy_page_range is more 604 * efficient than faulting. 605 */ 606 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 607 if (!vma->anon_vma) 608 return 0; 609 } 610 611 if (is_vm_hugetlb_page(vma)) 612 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 613 614 dst_pgd = pgd_offset(dst_mm, addr); 615 src_pgd = pgd_offset(src_mm, addr); 616 do { 617 next = pgd_addr_end(addr, end); 618 if (pgd_none_or_clear_bad(src_pgd)) 619 continue; 620 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 621 vma, addr, next)) 622 return -ENOMEM; 623 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 624 return 0; 625 } 626 627 static unsigned long zap_pte_range(struct mmu_gather *tlb, 628 struct vm_area_struct *vma, pmd_t *pmd, 629 unsigned long addr, unsigned long end, 630 long *zap_work, struct zap_details *details) 631 { 632 struct mm_struct *mm = tlb->mm; 633 pte_t *pte; 634 spinlock_t *ptl; 635 int file_rss = 0; 636 int anon_rss = 0; 637 638 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 639 arch_enter_lazy_mmu_mode(); 640 do { 641 pte_t ptent = *pte; 642 if (pte_none(ptent)) { 643 (*zap_work)--; 644 continue; 645 } 646 647 (*zap_work) -= PAGE_SIZE; 648 649 if (pte_present(ptent)) { 650 struct page *page; 651 652 page = vm_normal_page(vma, addr, ptent); 653 if (unlikely(details) && page) { 654 /* 655 * unmap_shared_mapping_pages() wants to 656 * invalidate cache without truncating: 657 * unmap shared but keep private pages. 658 */ 659 if (details->check_mapping && 660 details->check_mapping != page->mapping) 661 continue; 662 /* 663 * Each page->index must be checked when 664 * invalidating or truncating nonlinear. 665 */ 666 if (details->nonlinear_vma && 667 (page->index < details->first_index || 668 page->index > details->last_index)) 669 continue; 670 } 671 ptent = ptep_get_and_clear_full(mm, addr, pte, 672 tlb->fullmm); 673 tlb_remove_tlb_entry(tlb, pte, addr); 674 if (unlikely(!page)) 675 continue; 676 if (unlikely(details) && details->nonlinear_vma 677 && linear_page_index(details->nonlinear_vma, 678 addr) != page->index) 679 set_pte_at(mm, addr, pte, 680 pgoff_to_pte(page->index)); 681 if (PageAnon(page)) 682 anon_rss--; 683 else { 684 if (pte_dirty(ptent)) 685 set_page_dirty(page); 686 if (pte_young(ptent)) 687 SetPageReferenced(page); 688 file_rss--; 689 } 690 page_remove_rmap(page, vma); 691 tlb_remove_page(tlb, page); 692 continue; 693 } 694 /* 695 * If details->check_mapping, we leave swap entries; 696 * if details->nonlinear_vma, we leave file entries. 697 */ 698 if (unlikely(details)) 699 continue; 700 if (!pte_file(ptent)) 701 free_swap_and_cache(pte_to_swp_entry(ptent)); 702 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 703 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 704 705 add_mm_rss(mm, file_rss, anon_rss); 706 arch_leave_lazy_mmu_mode(); 707 pte_unmap_unlock(pte - 1, ptl); 708 709 return addr; 710 } 711 712 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 713 struct vm_area_struct *vma, pud_t *pud, 714 unsigned long addr, unsigned long end, 715 long *zap_work, struct zap_details *details) 716 { 717 pmd_t *pmd; 718 unsigned long next; 719 720 pmd = pmd_offset(pud, addr); 721 do { 722 next = pmd_addr_end(addr, end); 723 if (pmd_none_or_clear_bad(pmd)) { 724 (*zap_work)--; 725 continue; 726 } 727 next = zap_pte_range(tlb, vma, pmd, addr, next, 728 zap_work, details); 729 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 730 731 return addr; 732 } 733 734 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 735 struct vm_area_struct *vma, pgd_t *pgd, 736 unsigned long addr, unsigned long end, 737 long *zap_work, struct zap_details *details) 738 { 739 pud_t *pud; 740 unsigned long next; 741 742 pud = pud_offset(pgd, addr); 743 do { 744 next = pud_addr_end(addr, end); 745 if (pud_none_or_clear_bad(pud)) { 746 (*zap_work)--; 747 continue; 748 } 749 next = zap_pmd_range(tlb, vma, pud, addr, next, 750 zap_work, details); 751 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 752 753 return addr; 754 } 755 756 static unsigned long unmap_page_range(struct mmu_gather *tlb, 757 struct vm_area_struct *vma, 758 unsigned long addr, unsigned long end, 759 long *zap_work, struct zap_details *details) 760 { 761 pgd_t *pgd; 762 unsigned long next; 763 764 if (details && !details->check_mapping && !details->nonlinear_vma) 765 details = NULL; 766 767 BUG_ON(addr >= end); 768 tlb_start_vma(tlb, vma); 769 pgd = pgd_offset(vma->vm_mm, addr); 770 do { 771 next = pgd_addr_end(addr, end); 772 if (pgd_none_or_clear_bad(pgd)) { 773 (*zap_work)--; 774 continue; 775 } 776 next = zap_pud_range(tlb, vma, pgd, addr, next, 777 zap_work, details); 778 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 779 tlb_end_vma(tlb, vma); 780 781 return addr; 782 } 783 784 #ifdef CONFIG_PREEMPT 785 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 786 #else 787 /* No preempt: go for improved straight-line efficiency */ 788 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 789 #endif 790 791 /** 792 * unmap_vmas - unmap a range of memory covered by a list of vma's 793 * @tlbp: address of the caller's struct mmu_gather 794 * @vma: the starting vma 795 * @start_addr: virtual address at which to start unmapping 796 * @end_addr: virtual address at which to end unmapping 797 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 798 * @details: details of nonlinear truncation or shared cache invalidation 799 * 800 * Returns the end address of the unmapping (restart addr if interrupted). 801 * 802 * Unmap all pages in the vma list. 803 * 804 * We aim to not hold locks for too long (for scheduling latency reasons). 805 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 806 * return the ending mmu_gather to the caller. 807 * 808 * Only addresses between `start' and `end' will be unmapped. 809 * 810 * The VMA list must be sorted in ascending virtual address order. 811 * 812 * unmap_vmas() assumes that the caller will flush the whole unmapped address 813 * range after unmap_vmas() returns. So the only responsibility here is to 814 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 815 * drops the lock and schedules. 816 */ 817 unsigned long unmap_vmas(struct mmu_gather **tlbp, 818 struct vm_area_struct *vma, unsigned long start_addr, 819 unsigned long end_addr, unsigned long *nr_accounted, 820 struct zap_details *details) 821 { 822 long zap_work = ZAP_BLOCK_SIZE; 823 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 824 int tlb_start_valid = 0; 825 unsigned long start = start_addr; 826 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 827 int fullmm = (*tlbp)->fullmm; 828 829 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 830 unsigned long end; 831 832 start = max(vma->vm_start, start_addr); 833 if (start >= vma->vm_end) 834 continue; 835 end = min(vma->vm_end, end_addr); 836 if (end <= vma->vm_start) 837 continue; 838 839 if (vma->vm_flags & VM_ACCOUNT) 840 *nr_accounted += (end - start) >> PAGE_SHIFT; 841 842 while (start != end) { 843 if (!tlb_start_valid) { 844 tlb_start = start; 845 tlb_start_valid = 1; 846 } 847 848 if (unlikely(is_vm_hugetlb_page(vma))) { 849 unmap_hugepage_range(vma, start, end); 850 zap_work -= (end - start) / 851 (HPAGE_SIZE / PAGE_SIZE); 852 start = end; 853 } else 854 start = unmap_page_range(*tlbp, vma, 855 start, end, &zap_work, details); 856 857 if (zap_work > 0) { 858 BUG_ON(start != end); 859 break; 860 } 861 862 tlb_finish_mmu(*tlbp, tlb_start, start); 863 864 if (need_resched() || 865 (i_mmap_lock && spin_needbreak(i_mmap_lock))) { 866 if (i_mmap_lock) { 867 *tlbp = NULL; 868 goto out; 869 } 870 cond_resched(); 871 } 872 873 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 874 tlb_start_valid = 0; 875 zap_work = ZAP_BLOCK_SIZE; 876 } 877 } 878 out: 879 return start; /* which is now the end (or restart) address */ 880 } 881 882 /** 883 * zap_page_range - remove user pages in a given range 884 * @vma: vm_area_struct holding the applicable pages 885 * @address: starting address of pages to zap 886 * @size: number of bytes to zap 887 * @details: details of nonlinear truncation or shared cache invalidation 888 */ 889 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 890 unsigned long size, struct zap_details *details) 891 { 892 struct mm_struct *mm = vma->vm_mm; 893 struct mmu_gather *tlb; 894 unsigned long end = address + size; 895 unsigned long nr_accounted = 0; 896 897 lru_add_drain(); 898 tlb = tlb_gather_mmu(mm, 0); 899 update_hiwater_rss(mm); 900 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 901 if (tlb) 902 tlb_finish_mmu(tlb, address, end); 903 return end; 904 } 905 906 /* 907 * Do a quick page-table lookup for a single page. 908 */ 909 struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 910 unsigned int flags) 911 { 912 pgd_t *pgd; 913 pud_t *pud; 914 pmd_t *pmd; 915 pte_t *ptep, pte; 916 spinlock_t *ptl; 917 struct page *page; 918 struct mm_struct *mm = vma->vm_mm; 919 920 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 921 if (!IS_ERR(page)) { 922 BUG_ON(flags & FOLL_GET); 923 goto out; 924 } 925 926 page = NULL; 927 pgd = pgd_offset(mm, address); 928 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 929 goto no_page_table; 930 931 pud = pud_offset(pgd, address); 932 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 933 goto no_page_table; 934 935 pmd = pmd_offset(pud, address); 936 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 937 goto no_page_table; 938 939 if (pmd_huge(*pmd)) { 940 BUG_ON(flags & FOLL_GET); 941 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 942 goto out; 943 } 944 945 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 946 if (!ptep) 947 goto out; 948 949 pte = *ptep; 950 if (!pte_present(pte)) 951 goto unlock; 952 if ((flags & FOLL_WRITE) && !pte_write(pte)) 953 goto unlock; 954 page = vm_normal_page(vma, address, pte); 955 if (unlikely(!page)) 956 goto unlock; 957 958 if (flags & FOLL_GET) 959 get_page(page); 960 if (flags & FOLL_TOUCH) { 961 if ((flags & FOLL_WRITE) && 962 !pte_dirty(pte) && !PageDirty(page)) 963 set_page_dirty(page); 964 mark_page_accessed(page); 965 } 966 unlock: 967 pte_unmap_unlock(ptep, ptl); 968 out: 969 return page; 970 971 no_page_table: 972 /* 973 * When core dumping an enormous anonymous area that nobody 974 * has touched so far, we don't want to allocate page tables. 975 */ 976 if (flags & FOLL_ANON) { 977 page = ZERO_PAGE(0); 978 if (flags & FOLL_GET) 979 get_page(page); 980 BUG_ON(flags & FOLL_WRITE); 981 } 982 return page; 983 } 984 985 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 986 unsigned long start, int len, int write, int force, 987 struct page **pages, struct vm_area_struct **vmas) 988 { 989 int i; 990 unsigned int vm_flags; 991 992 if (len <= 0) 993 return 0; 994 /* 995 * Require read or write permissions. 996 * If 'force' is set, we only require the "MAY" flags. 997 */ 998 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 999 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 1000 i = 0; 1001 1002 do { 1003 struct vm_area_struct *vma; 1004 unsigned int foll_flags; 1005 1006 vma = find_extend_vma(mm, start); 1007 if (!vma && in_gate_area(tsk, start)) { 1008 unsigned long pg = start & PAGE_MASK; 1009 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 1010 pgd_t *pgd; 1011 pud_t *pud; 1012 pmd_t *pmd; 1013 pte_t *pte; 1014 if (write) /* user gate pages are read-only */ 1015 return i ? : -EFAULT; 1016 if (pg > TASK_SIZE) 1017 pgd = pgd_offset_k(pg); 1018 else 1019 pgd = pgd_offset_gate(mm, pg); 1020 BUG_ON(pgd_none(*pgd)); 1021 pud = pud_offset(pgd, pg); 1022 BUG_ON(pud_none(*pud)); 1023 pmd = pmd_offset(pud, pg); 1024 if (pmd_none(*pmd)) 1025 return i ? : -EFAULT; 1026 pte = pte_offset_map(pmd, pg); 1027 if (pte_none(*pte)) { 1028 pte_unmap(pte); 1029 return i ? : -EFAULT; 1030 } 1031 if (pages) { 1032 struct page *page = vm_normal_page(gate_vma, start, *pte); 1033 pages[i] = page; 1034 if (page) 1035 get_page(page); 1036 } 1037 pte_unmap(pte); 1038 if (vmas) 1039 vmas[i] = gate_vma; 1040 i++; 1041 start += PAGE_SIZE; 1042 len--; 1043 continue; 1044 } 1045 1046 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP)) 1047 || !(vm_flags & vma->vm_flags)) 1048 return i ? : -EFAULT; 1049 1050 if (is_vm_hugetlb_page(vma)) { 1051 i = follow_hugetlb_page(mm, vma, pages, vmas, 1052 &start, &len, i, write); 1053 continue; 1054 } 1055 1056 foll_flags = FOLL_TOUCH; 1057 if (pages) 1058 foll_flags |= FOLL_GET; 1059 if (!write && !(vma->vm_flags & VM_LOCKED) && 1060 (!vma->vm_ops || (!vma->vm_ops->nopage && 1061 !vma->vm_ops->fault))) 1062 foll_flags |= FOLL_ANON; 1063 1064 do { 1065 struct page *page; 1066 1067 /* 1068 * If tsk is ooming, cut off its access to large memory 1069 * allocations. It has a pending SIGKILL, but it can't 1070 * be processed until returning to user space. 1071 */ 1072 if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE))) 1073 return -ENOMEM; 1074 1075 if (write) 1076 foll_flags |= FOLL_WRITE; 1077 1078 cond_resched(); 1079 while (!(page = follow_page(vma, start, foll_flags))) { 1080 int ret; 1081 ret = handle_mm_fault(mm, vma, start, 1082 foll_flags & FOLL_WRITE); 1083 if (ret & VM_FAULT_ERROR) { 1084 if (ret & VM_FAULT_OOM) 1085 return i ? i : -ENOMEM; 1086 else if (ret & VM_FAULT_SIGBUS) 1087 return i ? i : -EFAULT; 1088 BUG(); 1089 } 1090 if (ret & VM_FAULT_MAJOR) 1091 tsk->maj_flt++; 1092 else 1093 tsk->min_flt++; 1094 1095 /* 1096 * The VM_FAULT_WRITE bit tells us that 1097 * do_wp_page has broken COW when necessary, 1098 * even if maybe_mkwrite decided not to set 1099 * pte_write. We can thus safely do subsequent 1100 * page lookups as if they were reads. 1101 */ 1102 if (ret & VM_FAULT_WRITE) 1103 foll_flags &= ~FOLL_WRITE; 1104 1105 cond_resched(); 1106 } 1107 if (pages) { 1108 pages[i] = page; 1109 1110 flush_anon_page(vma, page, start); 1111 flush_dcache_page(page); 1112 } 1113 if (vmas) 1114 vmas[i] = vma; 1115 i++; 1116 start += PAGE_SIZE; 1117 len--; 1118 } while (len && start < vma->vm_end); 1119 } while (len); 1120 return i; 1121 } 1122 EXPORT_SYMBOL(get_user_pages); 1123 1124 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr, 1125 spinlock_t **ptl) 1126 { 1127 pgd_t * pgd = pgd_offset(mm, addr); 1128 pud_t * pud = pud_alloc(mm, pgd, addr); 1129 if (pud) { 1130 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1131 if (pmd) 1132 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1133 } 1134 return NULL; 1135 } 1136 1137 /* 1138 * This is the old fallback for page remapping. 1139 * 1140 * For historical reasons, it only allows reserved pages. Only 1141 * old drivers should use this, and they needed to mark their 1142 * pages reserved for the old functions anyway. 1143 */ 1144 static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot) 1145 { 1146 int retval; 1147 pte_t *pte; 1148 spinlock_t *ptl; 1149 1150 retval = mem_cgroup_charge(page, mm, GFP_KERNEL); 1151 if (retval) 1152 goto out; 1153 1154 retval = -EINVAL; 1155 if (PageAnon(page)) 1156 goto out_uncharge; 1157 retval = -ENOMEM; 1158 flush_dcache_page(page); 1159 pte = get_locked_pte(mm, addr, &ptl); 1160 if (!pte) 1161 goto out_uncharge; 1162 retval = -EBUSY; 1163 if (!pte_none(*pte)) 1164 goto out_unlock; 1165 1166 /* Ok, finally just insert the thing.. */ 1167 get_page(page); 1168 inc_mm_counter(mm, file_rss); 1169 page_add_file_rmap(page); 1170 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1171 1172 retval = 0; 1173 pte_unmap_unlock(pte, ptl); 1174 return retval; 1175 out_unlock: 1176 pte_unmap_unlock(pte, ptl); 1177 out_uncharge: 1178 mem_cgroup_uncharge_page(page); 1179 out: 1180 return retval; 1181 } 1182 1183 /** 1184 * vm_insert_page - insert single page into user vma 1185 * @vma: user vma to map to 1186 * @addr: target user address of this page 1187 * @page: source kernel page 1188 * 1189 * This allows drivers to insert individual pages they've allocated 1190 * into a user vma. 1191 * 1192 * The page has to be a nice clean _individual_ kernel allocation. 1193 * If you allocate a compound page, you need to have marked it as 1194 * such (__GFP_COMP), or manually just split the page up yourself 1195 * (see split_page()). 1196 * 1197 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1198 * took an arbitrary page protection parameter. This doesn't allow 1199 * that. Your vma protection will have to be set up correctly, which 1200 * means that if you want a shared writable mapping, you'd better 1201 * ask for a shared writable mapping! 1202 * 1203 * The page does not need to be reserved. 1204 */ 1205 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page) 1206 { 1207 if (addr < vma->vm_start || addr >= vma->vm_end) 1208 return -EFAULT; 1209 if (!page_count(page)) 1210 return -EINVAL; 1211 vma->vm_flags |= VM_INSERTPAGE; 1212 return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot); 1213 } 1214 EXPORT_SYMBOL(vm_insert_page); 1215 1216 /** 1217 * vm_insert_pfn - insert single pfn into user vma 1218 * @vma: user vma to map to 1219 * @addr: target user address of this page 1220 * @pfn: source kernel pfn 1221 * 1222 * Similar to vm_inert_page, this allows drivers to insert individual pages 1223 * they've allocated into a user vma. Same comments apply. 1224 * 1225 * This function should only be called from a vm_ops->fault handler, and 1226 * in that case the handler should return NULL. 1227 */ 1228 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1229 unsigned long pfn) 1230 { 1231 struct mm_struct *mm = vma->vm_mm; 1232 int retval; 1233 pte_t *pte, entry; 1234 spinlock_t *ptl; 1235 1236 BUG_ON(!(vma->vm_flags & VM_PFNMAP)); 1237 BUG_ON(is_cow_mapping(vma->vm_flags)); 1238 1239 retval = -ENOMEM; 1240 pte = get_locked_pte(mm, addr, &ptl); 1241 if (!pte) 1242 goto out; 1243 retval = -EBUSY; 1244 if (!pte_none(*pte)) 1245 goto out_unlock; 1246 1247 /* Ok, finally just insert the thing.. */ 1248 entry = pfn_pte(pfn, vma->vm_page_prot); 1249 set_pte_at(mm, addr, pte, entry); 1250 update_mmu_cache(vma, addr, entry); 1251 1252 retval = 0; 1253 out_unlock: 1254 pte_unmap_unlock(pte, ptl); 1255 1256 out: 1257 return retval; 1258 } 1259 EXPORT_SYMBOL(vm_insert_pfn); 1260 1261 /* 1262 * maps a range of physical memory into the requested pages. the old 1263 * mappings are removed. any references to nonexistent pages results 1264 * in null mappings (currently treated as "copy-on-access") 1265 */ 1266 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1267 unsigned long addr, unsigned long end, 1268 unsigned long pfn, pgprot_t prot) 1269 { 1270 pte_t *pte; 1271 spinlock_t *ptl; 1272 1273 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1274 if (!pte) 1275 return -ENOMEM; 1276 arch_enter_lazy_mmu_mode(); 1277 do { 1278 BUG_ON(!pte_none(*pte)); 1279 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); 1280 pfn++; 1281 } while (pte++, addr += PAGE_SIZE, addr != end); 1282 arch_leave_lazy_mmu_mode(); 1283 pte_unmap_unlock(pte - 1, ptl); 1284 return 0; 1285 } 1286 1287 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1288 unsigned long addr, unsigned long end, 1289 unsigned long pfn, pgprot_t prot) 1290 { 1291 pmd_t *pmd; 1292 unsigned long next; 1293 1294 pfn -= addr >> PAGE_SHIFT; 1295 pmd = pmd_alloc(mm, pud, addr); 1296 if (!pmd) 1297 return -ENOMEM; 1298 do { 1299 next = pmd_addr_end(addr, end); 1300 if (remap_pte_range(mm, pmd, addr, next, 1301 pfn + (addr >> PAGE_SHIFT), prot)) 1302 return -ENOMEM; 1303 } while (pmd++, addr = next, addr != end); 1304 return 0; 1305 } 1306 1307 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1308 unsigned long addr, unsigned long end, 1309 unsigned long pfn, pgprot_t prot) 1310 { 1311 pud_t *pud; 1312 unsigned long next; 1313 1314 pfn -= addr >> PAGE_SHIFT; 1315 pud = pud_alloc(mm, pgd, addr); 1316 if (!pud) 1317 return -ENOMEM; 1318 do { 1319 next = pud_addr_end(addr, end); 1320 if (remap_pmd_range(mm, pud, addr, next, 1321 pfn + (addr >> PAGE_SHIFT), prot)) 1322 return -ENOMEM; 1323 } while (pud++, addr = next, addr != end); 1324 return 0; 1325 } 1326 1327 /** 1328 * remap_pfn_range - remap kernel memory to userspace 1329 * @vma: user vma to map to 1330 * @addr: target user address to start at 1331 * @pfn: physical address of kernel memory 1332 * @size: size of map area 1333 * @prot: page protection flags for this mapping 1334 * 1335 * Note: this is only safe if the mm semaphore is held when called. 1336 */ 1337 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1338 unsigned long pfn, unsigned long size, pgprot_t prot) 1339 { 1340 pgd_t *pgd; 1341 unsigned long next; 1342 unsigned long end = addr + PAGE_ALIGN(size); 1343 struct mm_struct *mm = vma->vm_mm; 1344 int err; 1345 1346 /* 1347 * Physically remapped pages are special. Tell the 1348 * rest of the world about it: 1349 * VM_IO tells people not to look at these pages 1350 * (accesses can have side effects). 1351 * VM_RESERVED is specified all over the place, because 1352 * in 2.4 it kept swapout's vma scan off this vma; but 1353 * in 2.6 the LRU scan won't even find its pages, so this 1354 * flag means no more than count its pages in reserved_vm, 1355 * and omit it from core dump, even when VM_IO turned off. 1356 * VM_PFNMAP tells the core MM that the base pages are just 1357 * raw PFN mappings, and do not have a "struct page" associated 1358 * with them. 1359 * 1360 * There's a horrible special case to handle copy-on-write 1361 * behaviour that some programs depend on. We mark the "original" 1362 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1363 */ 1364 if (is_cow_mapping(vma->vm_flags)) { 1365 if (addr != vma->vm_start || end != vma->vm_end) 1366 return -EINVAL; 1367 vma->vm_pgoff = pfn; 1368 } 1369 1370 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 1371 1372 BUG_ON(addr >= end); 1373 pfn -= addr >> PAGE_SHIFT; 1374 pgd = pgd_offset(mm, addr); 1375 flush_cache_range(vma, addr, end); 1376 do { 1377 next = pgd_addr_end(addr, end); 1378 err = remap_pud_range(mm, pgd, addr, next, 1379 pfn + (addr >> PAGE_SHIFT), prot); 1380 if (err) 1381 break; 1382 } while (pgd++, addr = next, addr != end); 1383 return err; 1384 } 1385 EXPORT_SYMBOL(remap_pfn_range); 1386 1387 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 1388 unsigned long addr, unsigned long end, 1389 pte_fn_t fn, void *data) 1390 { 1391 pte_t *pte; 1392 int err; 1393 pgtable_t token; 1394 spinlock_t *uninitialized_var(ptl); 1395 1396 pte = (mm == &init_mm) ? 1397 pte_alloc_kernel(pmd, addr) : 1398 pte_alloc_map_lock(mm, pmd, addr, &ptl); 1399 if (!pte) 1400 return -ENOMEM; 1401 1402 BUG_ON(pmd_huge(*pmd)); 1403 1404 token = pmd_pgtable(*pmd); 1405 1406 do { 1407 err = fn(pte, token, addr, data); 1408 if (err) 1409 break; 1410 } while (pte++, addr += PAGE_SIZE, addr != end); 1411 1412 if (mm != &init_mm) 1413 pte_unmap_unlock(pte-1, ptl); 1414 return err; 1415 } 1416 1417 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 1418 unsigned long addr, unsigned long end, 1419 pte_fn_t fn, void *data) 1420 { 1421 pmd_t *pmd; 1422 unsigned long next; 1423 int err; 1424 1425 pmd = pmd_alloc(mm, pud, addr); 1426 if (!pmd) 1427 return -ENOMEM; 1428 do { 1429 next = pmd_addr_end(addr, end); 1430 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 1431 if (err) 1432 break; 1433 } while (pmd++, addr = next, addr != end); 1434 return err; 1435 } 1436 1437 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 1438 unsigned long addr, unsigned long end, 1439 pte_fn_t fn, void *data) 1440 { 1441 pud_t *pud; 1442 unsigned long next; 1443 int err; 1444 1445 pud = pud_alloc(mm, pgd, addr); 1446 if (!pud) 1447 return -ENOMEM; 1448 do { 1449 next = pud_addr_end(addr, end); 1450 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 1451 if (err) 1452 break; 1453 } while (pud++, addr = next, addr != end); 1454 return err; 1455 } 1456 1457 /* 1458 * Scan a region of virtual memory, filling in page tables as necessary 1459 * and calling a provided function on each leaf page table. 1460 */ 1461 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 1462 unsigned long size, pte_fn_t fn, void *data) 1463 { 1464 pgd_t *pgd; 1465 unsigned long next; 1466 unsigned long end = addr + size; 1467 int err; 1468 1469 BUG_ON(addr >= end); 1470 pgd = pgd_offset(mm, addr); 1471 do { 1472 next = pgd_addr_end(addr, end); 1473 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 1474 if (err) 1475 break; 1476 } while (pgd++, addr = next, addr != end); 1477 return err; 1478 } 1479 EXPORT_SYMBOL_GPL(apply_to_page_range); 1480 1481 /* 1482 * handle_pte_fault chooses page fault handler according to an entry 1483 * which was read non-atomically. Before making any commitment, on 1484 * those architectures or configurations (e.g. i386 with PAE) which 1485 * might give a mix of unmatched parts, do_swap_page and do_file_page 1486 * must check under lock before unmapping the pte and proceeding 1487 * (but do_wp_page is only called after already making such a check; 1488 * and do_anonymous_page and do_no_page can safely check later on). 1489 */ 1490 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1491 pte_t *page_table, pte_t orig_pte) 1492 { 1493 int same = 1; 1494 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1495 if (sizeof(pte_t) > sizeof(unsigned long)) { 1496 spinlock_t *ptl = pte_lockptr(mm, pmd); 1497 spin_lock(ptl); 1498 same = pte_same(*page_table, orig_pte); 1499 spin_unlock(ptl); 1500 } 1501 #endif 1502 pte_unmap(page_table); 1503 return same; 1504 } 1505 1506 /* 1507 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1508 * servicing faults for write access. In the normal case, do always want 1509 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1510 * that do not have writing enabled, when used by access_process_vm. 1511 */ 1512 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1513 { 1514 if (likely(vma->vm_flags & VM_WRITE)) 1515 pte = pte_mkwrite(pte); 1516 return pte; 1517 } 1518 1519 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1520 { 1521 /* 1522 * If the source page was a PFN mapping, we don't have 1523 * a "struct page" for it. We do a best-effort copy by 1524 * just copying from the original user address. If that 1525 * fails, we just zero-fill it. Live with it. 1526 */ 1527 if (unlikely(!src)) { 1528 void *kaddr = kmap_atomic(dst, KM_USER0); 1529 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1530 1531 /* 1532 * This really shouldn't fail, because the page is there 1533 * in the page tables. But it might just be unreadable, 1534 * in which case we just give up and fill the result with 1535 * zeroes. 1536 */ 1537 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1538 memset(kaddr, 0, PAGE_SIZE); 1539 kunmap_atomic(kaddr, KM_USER0); 1540 flush_dcache_page(dst); 1541 } else 1542 copy_user_highpage(dst, src, va, vma); 1543 } 1544 1545 /* 1546 * This routine handles present pages, when users try to write 1547 * to a shared page. It is done by copying the page to a new address 1548 * and decrementing the shared-page counter for the old page. 1549 * 1550 * Note that this routine assumes that the protection checks have been 1551 * done by the caller (the low-level page fault routine in most cases). 1552 * Thus we can safely just mark it writable once we've done any necessary 1553 * COW. 1554 * 1555 * We also mark the page dirty at this point even though the page will 1556 * change only once the write actually happens. This avoids a few races, 1557 * and potentially makes it more efficient. 1558 * 1559 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1560 * but allow concurrent faults), with pte both mapped and locked. 1561 * We return with mmap_sem still held, but pte unmapped and unlocked. 1562 */ 1563 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1564 unsigned long address, pte_t *page_table, pmd_t *pmd, 1565 spinlock_t *ptl, pte_t orig_pte) 1566 { 1567 struct page *old_page, *new_page; 1568 pte_t entry; 1569 int reuse = 0, ret = 0; 1570 int page_mkwrite = 0; 1571 struct page *dirty_page = NULL; 1572 1573 old_page = vm_normal_page(vma, address, orig_pte); 1574 if (!old_page) 1575 goto gotten; 1576 1577 /* 1578 * Take out anonymous pages first, anonymous shared vmas are 1579 * not dirty accountable. 1580 */ 1581 if (PageAnon(old_page)) { 1582 if (!TestSetPageLocked(old_page)) { 1583 reuse = can_share_swap_page(old_page); 1584 unlock_page(old_page); 1585 } 1586 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 1587 (VM_WRITE|VM_SHARED))) { 1588 /* 1589 * Only catch write-faults on shared writable pages, 1590 * read-only shared pages can get COWed by 1591 * get_user_pages(.write=1, .force=1). 1592 */ 1593 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 1594 /* 1595 * Notify the address space that the page is about to 1596 * become writable so that it can prohibit this or wait 1597 * for the page to get into an appropriate state. 1598 * 1599 * We do this without the lock held, so that it can 1600 * sleep if it needs to. 1601 */ 1602 page_cache_get(old_page); 1603 pte_unmap_unlock(page_table, ptl); 1604 1605 if (vma->vm_ops->page_mkwrite(vma, old_page) < 0) 1606 goto unwritable_page; 1607 1608 /* 1609 * Since we dropped the lock we need to revalidate 1610 * the PTE as someone else may have changed it. If 1611 * they did, we just return, as we can count on the 1612 * MMU to tell us if they didn't also make it writable. 1613 */ 1614 page_table = pte_offset_map_lock(mm, pmd, address, 1615 &ptl); 1616 page_cache_release(old_page); 1617 if (!pte_same(*page_table, orig_pte)) 1618 goto unlock; 1619 1620 page_mkwrite = 1; 1621 } 1622 dirty_page = old_page; 1623 get_page(dirty_page); 1624 reuse = 1; 1625 } 1626 1627 if (reuse) { 1628 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1629 entry = pte_mkyoung(orig_pte); 1630 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1631 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 1632 update_mmu_cache(vma, address, entry); 1633 ret |= VM_FAULT_WRITE; 1634 goto unlock; 1635 } 1636 1637 /* 1638 * Ok, we need to copy. Oh, well.. 1639 */ 1640 page_cache_get(old_page); 1641 gotten: 1642 pte_unmap_unlock(page_table, ptl); 1643 1644 if (unlikely(anon_vma_prepare(vma))) 1645 goto oom; 1646 VM_BUG_ON(old_page == ZERO_PAGE(0)); 1647 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 1648 if (!new_page) 1649 goto oom; 1650 cow_user_page(new_page, old_page, address, vma); 1651 __SetPageUptodate(new_page); 1652 1653 if (mem_cgroup_charge(new_page, mm, GFP_KERNEL)) 1654 goto oom_free_new; 1655 1656 /* 1657 * Re-check the pte - we dropped the lock 1658 */ 1659 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1660 if (likely(pte_same(*page_table, orig_pte))) { 1661 if (old_page) { 1662 page_remove_rmap(old_page, vma); 1663 if (!PageAnon(old_page)) { 1664 dec_mm_counter(mm, file_rss); 1665 inc_mm_counter(mm, anon_rss); 1666 } 1667 } else 1668 inc_mm_counter(mm, anon_rss); 1669 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1670 entry = mk_pte(new_page, vma->vm_page_prot); 1671 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1672 /* 1673 * Clear the pte entry and flush it first, before updating the 1674 * pte with the new entry. This will avoid a race condition 1675 * seen in the presence of one thread doing SMC and another 1676 * thread doing COW. 1677 */ 1678 ptep_clear_flush(vma, address, page_table); 1679 set_pte_at(mm, address, page_table, entry); 1680 update_mmu_cache(vma, address, entry); 1681 lru_cache_add_active(new_page); 1682 page_add_new_anon_rmap(new_page, vma, address); 1683 1684 /* Free the old page.. */ 1685 new_page = old_page; 1686 ret |= VM_FAULT_WRITE; 1687 } else 1688 mem_cgroup_uncharge_page(new_page); 1689 1690 if (new_page) 1691 page_cache_release(new_page); 1692 if (old_page) 1693 page_cache_release(old_page); 1694 unlock: 1695 pte_unmap_unlock(page_table, ptl); 1696 if (dirty_page) { 1697 if (vma->vm_file) 1698 file_update_time(vma->vm_file); 1699 1700 /* 1701 * Yes, Virginia, this is actually required to prevent a race 1702 * with clear_page_dirty_for_io() from clearing the page dirty 1703 * bit after it clear all dirty ptes, but before a racing 1704 * do_wp_page installs a dirty pte. 1705 * 1706 * do_no_page is protected similarly. 1707 */ 1708 wait_on_page_locked(dirty_page); 1709 set_page_dirty_balance(dirty_page, page_mkwrite); 1710 put_page(dirty_page); 1711 } 1712 return ret; 1713 oom_free_new: 1714 page_cache_release(new_page); 1715 oom: 1716 if (old_page) 1717 page_cache_release(old_page); 1718 return VM_FAULT_OOM; 1719 1720 unwritable_page: 1721 page_cache_release(old_page); 1722 return VM_FAULT_SIGBUS; 1723 } 1724 1725 /* 1726 * Helper functions for unmap_mapping_range(). 1727 * 1728 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 1729 * 1730 * We have to restart searching the prio_tree whenever we drop the lock, 1731 * since the iterator is only valid while the lock is held, and anyway 1732 * a later vma might be split and reinserted earlier while lock dropped. 1733 * 1734 * The list of nonlinear vmas could be handled more efficiently, using 1735 * a placeholder, but handle it in the same way until a need is shown. 1736 * It is important to search the prio_tree before nonlinear list: a vma 1737 * may become nonlinear and be shifted from prio_tree to nonlinear list 1738 * while the lock is dropped; but never shifted from list to prio_tree. 1739 * 1740 * In order to make forward progress despite restarting the search, 1741 * vm_truncate_count is used to mark a vma as now dealt with, so we can 1742 * quickly skip it next time around. Since the prio_tree search only 1743 * shows us those vmas affected by unmapping the range in question, we 1744 * can't efficiently keep all vmas in step with mapping->truncate_count: 1745 * so instead reset them all whenever it wraps back to 0 (then go to 1). 1746 * mapping->truncate_count and vma->vm_truncate_count are protected by 1747 * i_mmap_lock. 1748 * 1749 * In order to make forward progress despite repeatedly restarting some 1750 * large vma, note the restart_addr from unmap_vmas when it breaks out: 1751 * and restart from that address when we reach that vma again. It might 1752 * have been split or merged, shrunk or extended, but never shifted: so 1753 * restart_addr remains valid so long as it remains in the vma's range. 1754 * unmap_mapping_range forces truncate_count to leap over page-aligned 1755 * values so we can save vma's restart_addr in its truncate_count field. 1756 */ 1757 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 1758 1759 static void reset_vma_truncate_counts(struct address_space *mapping) 1760 { 1761 struct vm_area_struct *vma; 1762 struct prio_tree_iter iter; 1763 1764 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 1765 vma->vm_truncate_count = 0; 1766 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 1767 vma->vm_truncate_count = 0; 1768 } 1769 1770 static int unmap_mapping_range_vma(struct vm_area_struct *vma, 1771 unsigned long start_addr, unsigned long end_addr, 1772 struct zap_details *details) 1773 { 1774 unsigned long restart_addr; 1775 int need_break; 1776 1777 /* 1778 * files that support invalidating or truncating portions of the 1779 * file from under mmaped areas must have their ->fault function 1780 * return a locked page (and set VM_FAULT_LOCKED in the return). 1781 * This provides synchronisation against concurrent unmapping here. 1782 */ 1783 1784 again: 1785 restart_addr = vma->vm_truncate_count; 1786 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 1787 start_addr = restart_addr; 1788 if (start_addr >= end_addr) { 1789 /* Top of vma has been split off since last time */ 1790 vma->vm_truncate_count = details->truncate_count; 1791 return 0; 1792 } 1793 } 1794 1795 restart_addr = zap_page_range(vma, start_addr, 1796 end_addr - start_addr, details); 1797 need_break = need_resched() || spin_needbreak(details->i_mmap_lock); 1798 1799 if (restart_addr >= end_addr) { 1800 /* We have now completed this vma: mark it so */ 1801 vma->vm_truncate_count = details->truncate_count; 1802 if (!need_break) 1803 return 0; 1804 } else { 1805 /* Note restart_addr in vma's truncate_count field */ 1806 vma->vm_truncate_count = restart_addr; 1807 if (!need_break) 1808 goto again; 1809 } 1810 1811 spin_unlock(details->i_mmap_lock); 1812 cond_resched(); 1813 spin_lock(details->i_mmap_lock); 1814 return -EINTR; 1815 } 1816 1817 static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 1818 struct zap_details *details) 1819 { 1820 struct vm_area_struct *vma; 1821 struct prio_tree_iter iter; 1822 pgoff_t vba, vea, zba, zea; 1823 1824 restart: 1825 vma_prio_tree_foreach(vma, &iter, root, 1826 details->first_index, details->last_index) { 1827 /* Skip quickly over those we have already dealt with */ 1828 if (vma->vm_truncate_count == details->truncate_count) 1829 continue; 1830 1831 vba = vma->vm_pgoff; 1832 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 1833 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 1834 zba = details->first_index; 1835 if (zba < vba) 1836 zba = vba; 1837 zea = details->last_index; 1838 if (zea > vea) 1839 zea = vea; 1840 1841 if (unmap_mapping_range_vma(vma, 1842 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 1843 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 1844 details) < 0) 1845 goto restart; 1846 } 1847 } 1848 1849 static inline void unmap_mapping_range_list(struct list_head *head, 1850 struct zap_details *details) 1851 { 1852 struct vm_area_struct *vma; 1853 1854 /* 1855 * In nonlinear VMAs there is no correspondence between virtual address 1856 * offset and file offset. So we must perform an exhaustive search 1857 * across *all* the pages in each nonlinear VMA, not just the pages 1858 * whose virtual address lies outside the file truncation point. 1859 */ 1860 restart: 1861 list_for_each_entry(vma, head, shared.vm_set.list) { 1862 /* Skip quickly over those we have already dealt with */ 1863 if (vma->vm_truncate_count == details->truncate_count) 1864 continue; 1865 details->nonlinear_vma = vma; 1866 if (unmap_mapping_range_vma(vma, vma->vm_start, 1867 vma->vm_end, details) < 0) 1868 goto restart; 1869 } 1870 } 1871 1872 /** 1873 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 1874 * @mapping: the address space containing mmaps to be unmapped. 1875 * @holebegin: byte in first page to unmap, relative to the start of 1876 * the underlying file. This will be rounded down to a PAGE_SIZE 1877 * boundary. Note that this is different from vmtruncate(), which 1878 * must keep the partial page. In contrast, we must get rid of 1879 * partial pages. 1880 * @holelen: size of prospective hole in bytes. This will be rounded 1881 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 1882 * end of the file. 1883 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 1884 * but 0 when invalidating pagecache, don't throw away private data. 1885 */ 1886 void unmap_mapping_range(struct address_space *mapping, 1887 loff_t const holebegin, loff_t const holelen, int even_cows) 1888 { 1889 struct zap_details details; 1890 pgoff_t hba = holebegin >> PAGE_SHIFT; 1891 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1892 1893 /* Check for overflow. */ 1894 if (sizeof(holelen) > sizeof(hlen)) { 1895 long long holeend = 1896 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1897 if (holeend & ~(long long)ULONG_MAX) 1898 hlen = ULONG_MAX - hba + 1; 1899 } 1900 1901 details.check_mapping = even_cows? NULL: mapping; 1902 details.nonlinear_vma = NULL; 1903 details.first_index = hba; 1904 details.last_index = hba + hlen - 1; 1905 if (details.last_index < details.first_index) 1906 details.last_index = ULONG_MAX; 1907 details.i_mmap_lock = &mapping->i_mmap_lock; 1908 1909 spin_lock(&mapping->i_mmap_lock); 1910 1911 /* Protect against endless unmapping loops */ 1912 mapping->truncate_count++; 1913 if (unlikely(is_restart_addr(mapping->truncate_count))) { 1914 if (mapping->truncate_count == 0) 1915 reset_vma_truncate_counts(mapping); 1916 mapping->truncate_count++; 1917 } 1918 details.truncate_count = mapping->truncate_count; 1919 1920 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 1921 unmap_mapping_range_tree(&mapping->i_mmap, &details); 1922 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 1923 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 1924 spin_unlock(&mapping->i_mmap_lock); 1925 } 1926 EXPORT_SYMBOL(unmap_mapping_range); 1927 1928 /** 1929 * vmtruncate - unmap mappings "freed" by truncate() syscall 1930 * @inode: inode of the file used 1931 * @offset: file offset to start truncating 1932 * 1933 * NOTE! We have to be ready to update the memory sharing 1934 * between the file and the memory map for a potential last 1935 * incomplete page. Ugly, but necessary. 1936 */ 1937 int vmtruncate(struct inode * inode, loff_t offset) 1938 { 1939 if (inode->i_size < offset) { 1940 unsigned long limit; 1941 1942 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1943 if (limit != RLIM_INFINITY && offset > limit) 1944 goto out_sig; 1945 if (offset > inode->i_sb->s_maxbytes) 1946 goto out_big; 1947 i_size_write(inode, offset); 1948 } else { 1949 struct address_space *mapping = inode->i_mapping; 1950 1951 /* 1952 * truncation of in-use swapfiles is disallowed - it would 1953 * cause subsequent swapout to scribble on the now-freed 1954 * blocks. 1955 */ 1956 if (IS_SWAPFILE(inode)) 1957 return -ETXTBSY; 1958 i_size_write(inode, offset); 1959 1960 /* 1961 * unmap_mapping_range is called twice, first simply for 1962 * efficiency so that truncate_inode_pages does fewer 1963 * single-page unmaps. However after this first call, and 1964 * before truncate_inode_pages finishes, it is possible for 1965 * private pages to be COWed, which remain after 1966 * truncate_inode_pages finishes, hence the second 1967 * unmap_mapping_range call must be made for correctness. 1968 */ 1969 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1970 truncate_inode_pages(mapping, offset); 1971 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1972 } 1973 1974 if (inode->i_op && inode->i_op->truncate) 1975 inode->i_op->truncate(inode); 1976 return 0; 1977 1978 out_sig: 1979 send_sig(SIGXFSZ, current, 0); 1980 out_big: 1981 return -EFBIG; 1982 } 1983 EXPORT_SYMBOL(vmtruncate); 1984 1985 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 1986 { 1987 struct address_space *mapping = inode->i_mapping; 1988 1989 /* 1990 * If the underlying filesystem is not going to provide 1991 * a way to truncate a range of blocks (punch a hole) - 1992 * we should return failure right now. 1993 */ 1994 if (!inode->i_op || !inode->i_op->truncate_range) 1995 return -ENOSYS; 1996 1997 mutex_lock(&inode->i_mutex); 1998 down_write(&inode->i_alloc_sem); 1999 unmap_mapping_range(mapping, offset, (end - offset), 1); 2000 truncate_inode_pages_range(mapping, offset, end); 2001 unmap_mapping_range(mapping, offset, (end - offset), 1); 2002 inode->i_op->truncate_range(inode, offset, end); 2003 up_write(&inode->i_alloc_sem); 2004 mutex_unlock(&inode->i_mutex); 2005 2006 return 0; 2007 } 2008 2009 /* 2010 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2011 * but allow concurrent faults), and pte mapped but not yet locked. 2012 * We return with mmap_sem still held, but pte unmapped and unlocked. 2013 */ 2014 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2015 unsigned long address, pte_t *page_table, pmd_t *pmd, 2016 int write_access, pte_t orig_pte) 2017 { 2018 spinlock_t *ptl; 2019 struct page *page; 2020 swp_entry_t entry; 2021 pte_t pte; 2022 int ret = 0; 2023 2024 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2025 goto out; 2026 2027 entry = pte_to_swp_entry(orig_pte); 2028 if (is_migration_entry(entry)) { 2029 migration_entry_wait(mm, pmd, address); 2030 goto out; 2031 } 2032 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2033 page = lookup_swap_cache(entry); 2034 if (!page) { 2035 grab_swap_token(); /* Contend for token _before_ read-in */ 2036 page = swapin_readahead(entry, 2037 GFP_HIGHUSER_MOVABLE, vma, address); 2038 if (!page) { 2039 /* 2040 * Back out if somebody else faulted in this pte 2041 * while we released the pte lock. 2042 */ 2043 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2044 if (likely(pte_same(*page_table, orig_pte))) 2045 ret = VM_FAULT_OOM; 2046 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2047 goto unlock; 2048 } 2049 2050 /* Had to read the page from swap area: Major fault */ 2051 ret = VM_FAULT_MAJOR; 2052 count_vm_event(PGMAJFAULT); 2053 } 2054 2055 if (mem_cgroup_charge(page, mm, GFP_KERNEL)) { 2056 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2057 ret = VM_FAULT_OOM; 2058 goto out; 2059 } 2060 2061 mark_page_accessed(page); 2062 lock_page(page); 2063 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2064 2065 /* 2066 * Back out if somebody else already faulted in this pte. 2067 */ 2068 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2069 if (unlikely(!pte_same(*page_table, orig_pte))) 2070 goto out_nomap; 2071 2072 if (unlikely(!PageUptodate(page))) { 2073 ret = VM_FAULT_SIGBUS; 2074 goto out_nomap; 2075 } 2076 2077 /* The page isn't present yet, go ahead with the fault. */ 2078 2079 inc_mm_counter(mm, anon_rss); 2080 pte = mk_pte(page, vma->vm_page_prot); 2081 if (write_access && can_share_swap_page(page)) { 2082 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2083 write_access = 0; 2084 } 2085 2086 flush_icache_page(vma, page); 2087 set_pte_at(mm, address, page_table, pte); 2088 page_add_anon_rmap(page, vma, address); 2089 2090 swap_free(entry); 2091 if (vm_swap_full()) 2092 remove_exclusive_swap_page(page); 2093 unlock_page(page); 2094 2095 if (write_access) { 2096 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 2097 if (ret & VM_FAULT_ERROR) 2098 ret &= VM_FAULT_ERROR; 2099 goto out; 2100 } 2101 2102 /* No need to invalidate - it was non-present before */ 2103 update_mmu_cache(vma, address, pte); 2104 unlock: 2105 pte_unmap_unlock(page_table, ptl); 2106 out: 2107 return ret; 2108 out_nomap: 2109 mem_cgroup_uncharge_page(page); 2110 pte_unmap_unlock(page_table, ptl); 2111 unlock_page(page); 2112 page_cache_release(page); 2113 return ret; 2114 } 2115 2116 /* 2117 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2118 * but allow concurrent faults), and pte mapped but not yet locked. 2119 * We return with mmap_sem still held, but pte unmapped and unlocked. 2120 */ 2121 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2122 unsigned long address, pte_t *page_table, pmd_t *pmd, 2123 int write_access) 2124 { 2125 struct page *page; 2126 spinlock_t *ptl; 2127 pte_t entry; 2128 2129 /* Allocate our own private page. */ 2130 pte_unmap(page_table); 2131 2132 if (unlikely(anon_vma_prepare(vma))) 2133 goto oom; 2134 page = alloc_zeroed_user_highpage_movable(vma, address); 2135 if (!page) 2136 goto oom; 2137 __SetPageUptodate(page); 2138 2139 if (mem_cgroup_charge(page, mm, GFP_KERNEL)) 2140 goto oom_free_page; 2141 2142 entry = mk_pte(page, vma->vm_page_prot); 2143 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2144 2145 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2146 if (!pte_none(*page_table)) 2147 goto release; 2148 inc_mm_counter(mm, anon_rss); 2149 lru_cache_add_active(page); 2150 page_add_new_anon_rmap(page, vma, address); 2151 set_pte_at(mm, address, page_table, entry); 2152 2153 /* No need to invalidate - it was non-present before */ 2154 update_mmu_cache(vma, address, entry); 2155 unlock: 2156 pte_unmap_unlock(page_table, ptl); 2157 return 0; 2158 release: 2159 mem_cgroup_uncharge_page(page); 2160 page_cache_release(page); 2161 goto unlock; 2162 oom_free_page: 2163 page_cache_release(page); 2164 oom: 2165 return VM_FAULT_OOM; 2166 } 2167 2168 /* 2169 * __do_fault() tries to create a new page mapping. It aggressively 2170 * tries to share with existing pages, but makes a separate copy if 2171 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 2172 * the next page fault. 2173 * 2174 * As this is called only for pages that do not currently exist, we 2175 * do not need to flush old virtual caches or the TLB. 2176 * 2177 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2178 * but allow concurrent faults), and pte neither mapped nor locked. 2179 * We return with mmap_sem still held, but pte unmapped and unlocked. 2180 */ 2181 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2182 unsigned long address, pmd_t *pmd, 2183 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2184 { 2185 pte_t *page_table; 2186 spinlock_t *ptl; 2187 struct page *page; 2188 pte_t entry; 2189 int anon = 0; 2190 struct page *dirty_page = NULL; 2191 struct vm_fault vmf; 2192 int ret; 2193 int page_mkwrite = 0; 2194 2195 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2196 vmf.pgoff = pgoff; 2197 vmf.flags = flags; 2198 vmf.page = NULL; 2199 2200 BUG_ON(vma->vm_flags & VM_PFNMAP); 2201 2202 if (likely(vma->vm_ops->fault)) { 2203 ret = vma->vm_ops->fault(vma, &vmf); 2204 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2205 return ret; 2206 } else { 2207 /* Legacy ->nopage path */ 2208 ret = 0; 2209 vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); 2210 /* no page was available -- either SIGBUS or OOM */ 2211 if (unlikely(vmf.page == NOPAGE_SIGBUS)) 2212 return VM_FAULT_SIGBUS; 2213 else if (unlikely(vmf.page == NOPAGE_OOM)) 2214 return VM_FAULT_OOM; 2215 } 2216 2217 /* 2218 * For consistency in subsequent calls, make the faulted page always 2219 * locked. 2220 */ 2221 if (unlikely(!(ret & VM_FAULT_LOCKED))) 2222 lock_page(vmf.page); 2223 else 2224 VM_BUG_ON(!PageLocked(vmf.page)); 2225 2226 /* 2227 * Should we do an early C-O-W break? 2228 */ 2229 page = vmf.page; 2230 if (flags & FAULT_FLAG_WRITE) { 2231 if (!(vma->vm_flags & VM_SHARED)) { 2232 anon = 1; 2233 if (unlikely(anon_vma_prepare(vma))) { 2234 ret = VM_FAULT_OOM; 2235 goto out; 2236 } 2237 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, 2238 vma, address); 2239 if (!page) { 2240 ret = VM_FAULT_OOM; 2241 goto out; 2242 } 2243 copy_user_highpage(page, vmf.page, address, vma); 2244 __SetPageUptodate(page); 2245 } else { 2246 /* 2247 * If the page will be shareable, see if the backing 2248 * address space wants to know that the page is about 2249 * to become writable 2250 */ 2251 if (vma->vm_ops->page_mkwrite) { 2252 unlock_page(page); 2253 if (vma->vm_ops->page_mkwrite(vma, page) < 0) { 2254 ret = VM_FAULT_SIGBUS; 2255 anon = 1; /* no anon but release vmf.page */ 2256 goto out_unlocked; 2257 } 2258 lock_page(page); 2259 /* 2260 * XXX: this is not quite right (racy vs 2261 * invalidate) to unlock and relock the page 2262 * like this, however a better fix requires 2263 * reworking page_mkwrite locking API, which 2264 * is better done later. 2265 */ 2266 if (!page->mapping) { 2267 ret = 0; 2268 anon = 1; /* no anon but release vmf.page */ 2269 goto out; 2270 } 2271 page_mkwrite = 1; 2272 } 2273 } 2274 2275 } 2276 2277 if (mem_cgroup_charge(page, mm, GFP_KERNEL)) { 2278 ret = VM_FAULT_OOM; 2279 goto out; 2280 } 2281 2282 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2283 2284 /* 2285 * This silly early PAGE_DIRTY setting removes a race 2286 * due to the bad i386 page protection. But it's valid 2287 * for other architectures too. 2288 * 2289 * Note that if write_access is true, we either now have 2290 * an exclusive copy of the page, or this is a shared mapping, 2291 * so we can make it writable and dirty to avoid having to 2292 * handle that later. 2293 */ 2294 /* Only go through if we didn't race with anybody else... */ 2295 if (likely(pte_same(*page_table, orig_pte))) { 2296 flush_icache_page(vma, page); 2297 entry = mk_pte(page, vma->vm_page_prot); 2298 if (flags & FAULT_FLAG_WRITE) 2299 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2300 set_pte_at(mm, address, page_table, entry); 2301 if (anon) { 2302 inc_mm_counter(mm, anon_rss); 2303 lru_cache_add_active(page); 2304 page_add_new_anon_rmap(page, vma, address); 2305 } else { 2306 inc_mm_counter(mm, file_rss); 2307 page_add_file_rmap(page); 2308 if (flags & FAULT_FLAG_WRITE) { 2309 dirty_page = page; 2310 get_page(dirty_page); 2311 } 2312 } 2313 2314 /* no need to invalidate: a not-present page won't be cached */ 2315 update_mmu_cache(vma, address, entry); 2316 } else { 2317 mem_cgroup_uncharge_page(page); 2318 if (anon) 2319 page_cache_release(page); 2320 else 2321 anon = 1; /* no anon but release faulted_page */ 2322 } 2323 2324 pte_unmap_unlock(page_table, ptl); 2325 2326 out: 2327 unlock_page(vmf.page); 2328 out_unlocked: 2329 if (anon) 2330 page_cache_release(vmf.page); 2331 else if (dirty_page) { 2332 if (vma->vm_file) 2333 file_update_time(vma->vm_file); 2334 2335 set_page_dirty_balance(dirty_page, page_mkwrite); 2336 put_page(dirty_page); 2337 } 2338 2339 return ret; 2340 } 2341 2342 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2343 unsigned long address, pte_t *page_table, pmd_t *pmd, 2344 int write_access, pte_t orig_pte) 2345 { 2346 pgoff_t pgoff = (((address & PAGE_MASK) 2347 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 2348 unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0); 2349 2350 pte_unmap(page_table); 2351 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2352 } 2353 2354 2355 /* 2356 * do_no_pfn() tries to create a new page mapping for a page without 2357 * a struct_page backing it 2358 * 2359 * As this is called only for pages that do not currently exist, we 2360 * do not need to flush old virtual caches or the TLB. 2361 * 2362 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2363 * but allow concurrent faults), and pte mapped but not yet locked. 2364 * We return with mmap_sem still held, but pte unmapped and unlocked. 2365 * 2366 * It is expected that the ->nopfn handler always returns the same pfn 2367 * for a given virtual mapping. 2368 * 2369 * Mark this `noinline' to prevent it from bloating the main pagefault code. 2370 */ 2371 static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma, 2372 unsigned long address, pte_t *page_table, pmd_t *pmd, 2373 int write_access) 2374 { 2375 spinlock_t *ptl; 2376 pte_t entry; 2377 unsigned long pfn; 2378 2379 pte_unmap(page_table); 2380 BUG_ON(!(vma->vm_flags & VM_PFNMAP)); 2381 BUG_ON(is_cow_mapping(vma->vm_flags)); 2382 2383 pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK); 2384 if (unlikely(pfn == NOPFN_OOM)) 2385 return VM_FAULT_OOM; 2386 else if (unlikely(pfn == NOPFN_SIGBUS)) 2387 return VM_FAULT_SIGBUS; 2388 else if (unlikely(pfn == NOPFN_REFAULT)) 2389 return 0; 2390 2391 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2392 2393 /* Only go through if we didn't race with anybody else... */ 2394 if (pte_none(*page_table)) { 2395 entry = pfn_pte(pfn, vma->vm_page_prot); 2396 if (write_access) 2397 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2398 set_pte_at(mm, address, page_table, entry); 2399 } 2400 pte_unmap_unlock(page_table, ptl); 2401 return 0; 2402 } 2403 2404 /* 2405 * Fault of a previously existing named mapping. Repopulate the pte 2406 * from the encoded file_pte if possible. This enables swappable 2407 * nonlinear vmas. 2408 * 2409 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2410 * but allow concurrent faults), and pte mapped but not yet locked. 2411 * We return with mmap_sem still held, but pte unmapped and unlocked. 2412 */ 2413 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2414 unsigned long address, pte_t *page_table, pmd_t *pmd, 2415 int write_access, pte_t orig_pte) 2416 { 2417 unsigned int flags = FAULT_FLAG_NONLINEAR | 2418 (write_access ? FAULT_FLAG_WRITE : 0); 2419 pgoff_t pgoff; 2420 2421 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2422 return 0; 2423 2424 if (unlikely(!(vma->vm_flags & VM_NONLINEAR) || 2425 !(vma->vm_flags & VM_CAN_NONLINEAR))) { 2426 /* 2427 * Page table corrupted: show pte and kill process. 2428 */ 2429 print_bad_pte(vma, orig_pte, address); 2430 return VM_FAULT_OOM; 2431 } 2432 2433 pgoff = pte_to_pgoff(orig_pte); 2434 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2435 } 2436 2437 /* 2438 * These routines also need to handle stuff like marking pages dirty 2439 * and/or accessed for architectures that don't do it in hardware (most 2440 * RISC architectures). The early dirtying is also good on the i386. 2441 * 2442 * There is also a hook called "update_mmu_cache()" that architectures 2443 * with external mmu caches can use to update those (ie the Sparc or 2444 * PowerPC hashed page tables that act as extended TLBs). 2445 * 2446 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2447 * but allow concurrent faults), and pte mapped but not yet locked. 2448 * We return with mmap_sem still held, but pte unmapped and unlocked. 2449 */ 2450 static inline int handle_pte_fault(struct mm_struct *mm, 2451 struct vm_area_struct *vma, unsigned long address, 2452 pte_t *pte, pmd_t *pmd, int write_access) 2453 { 2454 pte_t entry; 2455 spinlock_t *ptl; 2456 2457 entry = *pte; 2458 if (!pte_present(entry)) { 2459 if (pte_none(entry)) { 2460 if (vma->vm_ops) { 2461 if (vma->vm_ops->fault || vma->vm_ops->nopage) 2462 return do_linear_fault(mm, vma, address, 2463 pte, pmd, write_access, entry); 2464 if (unlikely(vma->vm_ops->nopfn)) 2465 return do_no_pfn(mm, vma, address, pte, 2466 pmd, write_access); 2467 } 2468 return do_anonymous_page(mm, vma, address, 2469 pte, pmd, write_access); 2470 } 2471 if (pte_file(entry)) 2472 return do_nonlinear_fault(mm, vma, address, 2473 pte, pmd, write_access, entry); 2474 return do_swap_page(mm, vma, address, 2475 pte, pmd, write_access, entry); 2476 } 2477 2478 ptl = pte_lockptr(mm, pmd); 2479 spin_lock(ptl); 2480 if (unlikely(!pte_same(*pte, entry))) 2481 goto unlock; 2482 if (write_access) { 2483 if (!pte_write(entry)) 2484 return do_wp_page(mm, vma, address, 2485 pte, pmd, ptl, entry); 2486 entry = pte_mkdirty(entry); 2487 } 2488 entry = pte_mkyoung(entry); 2489 if (ptep_set_access_flags(vma, address, pte, entry, write_access)) { 2490 update_mmu_cache(vma, address, entry); 2491 } else { 2492 /* 2493 * This is needed only for protection faults but the arch code 2494 * is not yet telling us if this is a protection fault or not. 2495 * This still avoids useless tlb flushes for .text page faults 2496 * with threads. 2497 */ 2498 if (write_access) 2499 flush_tlb_page(vma, address); 2500 } 2501 unlock: 2502 pte_unmap_unlock(pte, ptl); 2503 return 0; 2504 } 2505 2506 /* 2507 * By the time we get here, we already hold the mm semaphore 2508 */ 2509 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2510 unsigned long address, int write_access) 2511 { 2512 pgd_t *pgd; 2513 pud_t *pud; 2514 pmd_t *pmd; 2515 pte_t *pte; 2516 2517 __set_current_state(TASK_RUNNING); 2518 2519 count_vm_event(PGFAULT); 2520 2521 if (unlikely(is_vm_hugetlb_page(vma))) 2522 return hugetlb_fault(mm, vma, address, write_access); 2523 2524 pgd = pgd_offset(mm, address); 2525 pud = pud_alloc(mm, pgd, address); 2526 if (!pud) 2527 return VM_FAULT_OOM; 2528 pmd = pmd_alloc(mm, pud, address); 2529 if (!pmd) 2530 return VM_FAULT_OOM; 2531 pte = pte_alloc_map(mm, pmd, address); 2532 if (!pte) 2533 return VM_FAULT_OOM; 2534 2535 return handle_pte_fault(mm, vma, address, pte, pmd, write_access); 2536 } 2537 2538 #ifndef __PAGETABLE_PUD_FOLDED 2539 /* 2540 * Allocate page upper directory. 2541 * We've already handled the fast-path in-line. 2542 */ 2543 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2544 { 2545 pud_t *new = pud_alloc_one(mm, address); 2546 if (!new) 2547 return -ENOMEM; 2548 2549 spin_lock(&mm->page_table_lock); 2550 if (pgd_present(*pgd)) /* Another has populated it */ 2551 pud_free(mm, new); 2552 else 2553 pgd_populate(mm, pgd, new); 2554 spin_unlock(&mm->page_table_lock); 2555 return 0; 2556 } 2557 #endif /* __PAGETABLE_PUD_FOLDED */ 2558 2559 #ifndef __PAGETABLE_PMD_FOLDED 2560 /* 2561 * Allocate page middle directory. 2562 * We've already handled the fast-path in-line. 2563 */ 2564 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2565 { 2566 pmd_t *new = pmd_alloc_one(mm, address); 2567 if (!new) 2568 return -ENOMEM; 2569 2570 spin_lock(&mm->page_table_lock); 2571 #ifndef __ARCH_HAS_4LEVEL_HACK 2572 if (pud_present(*pud)) /* Another has populated it */ 2573 pmd_free(mm, new); 2574 else 2575 pud_populate(mm, pud, new); 2576 #else 2577 if (pgd_present(*pud)) /* Another has populated it */ 2578 pmd_free(mm, new); 2579 else 2580 pgd_populate(mm, pud, new); 2581 #endif /* __ARCH_HAS_4LEVEL_HACK */ 2582 spin_unlock(&mm->page_table_lock); 2583 return 0; 2584 } 2585 #endif /* __PAGETABLE_PMD_FOLDED */ 2586 2587 int make_pages_present(unsigned long addr, unsigned long end) 2588 { 2589 int ret, len, write; 2590 struct vm_area_struct * vma; 2591 2592 vma = find_vma(current->mm, addr); 2593 if (!vma) 2594 return -1; 2595 write = (vma->vm_flags & VM_WRITE) != 0; 2596 BUG_ON(addr >= end); 2597 BUG_ON(end > vma->vm_end); 2598 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; 2599 ret = get_user_pages(current, current->mm, addr, 2600 len, write, 0, NULL, NULL); 2601 if (ret < 0) 2602 return ret; 2603 return ret == len ? 0 : -1; 2604 } 2605 2606 #if !defined(__HAVE_ARCH_GATE_AREA) 2607 2608 #if defined(AT_SYSINFO_EHDR) 2609 static struct vm_area_struct gate_vma; 2610 2611 static int __init gate_vma_init(void) 2612 { 2613 gate_vma.vm_mm = NULL; 2614 gate_vma.vm_start = FIXADDR_USER_START; 2615 gate_vma.vm_end = FIXADDR_USER_END; 2616 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 2617 gate_vma.vm_page_prot = __P101; 2618 /* 2619 * Make sure the vDSO gets into every core dump. 2620 * Dumping its contents makes post-mortem fully interpretable later 2621 * without matching up the same kernel and hardware config to see 2622 * what PC values meant. 2623 */ 2624 gate_vma.vm_flags |= VM_ALWAYSDUMP; 2625 return 0; 2626 } 2627 __initcall(gate_vma_init); 2628 #endif 2629 2630 struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 2631 { 2632 #ifdef AT_SYSINFO_EHDR 2633 return &gate_vma; 2634 #else 2635 return NULL; 2636 #endif 2637 } 2638 2639 int in_gate_area_no_task(unsigned long addr) 2640 { 2641 #ifdef AT_SYSINFO_EHDR 2642 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 2643 return 1; 2644 #endif 2645 return 0; 2646 } 2647 2648 #endif /* __HAVE_ARCH_GATE_AREA */ 2649 2650 /* 2651 * Access another process' address space. 2652 * Source/target buffer must be kernel space, 2653 * Do not walk the page table directly, use get_user_pages 2654 */ 2655 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2656 { 2657 struct mm_struct *mm; 2658 struct vm_area_struct *vma; 2659 struct page *page; 2660 void *old_buf = buf; 2661 2662 mm = get_task_mm(tsk); 2663 if (!mm) 2664 return 0; 2665 2666 down_read(&mm->mmap_sem); 2667 /* ignore errors, just check how much was successfully transferred */ 2668 while (len) { 2669 int bytes, ret, offset; 2670 void *maddr; 2671 2672 ret = get_user_pages(tsk, mm, addr, 1, 2673 write, 1, &page, &vma); 2674 if (ret <= 0) 2675 break; 2676 2677 bytes = len; 2678 offset = addr & (PAGE_SIZE-1); 2679 if (bytes > PAGE_SIZE-offset) 2680 bytes = PAGE_SIZE-offset; 2681 2682 maddr = kmap(page); 2683 if (write) { 2684 copy_to_user_page(vma, page, addr, 2685 maddr + offset, buf, bytes); 2686 set_page_dirty_lock(page); 2687 } else { 2688 copy_from_user_page(vma, page, addr, 2689 buf, maddr + offset, bytes); 2690 } 2691 kunmap(page); 2692 page_cache_release(page); 2693 len -= bytes; 2694 buf += bytes; 2695 addr += bytes; 2696 } 2697 up_read(&mm->mmap_sem); 2698 mmput(mm); 2699 2700 return buf - old_buf; 2701 } 2702 2703 /* 2704 * Print the name of a VMA. 2705 */ 2706 void print_vma_addr(char *prefix, unsigned long ip) 2707 { 2708 struct mm_struct *mm = current->mm; 2709 struct vm_area_struct *vma; 2710 2711 /* 2712 * Do not print if we are in atomic 2713 * contexts (in exception stacks, etc.): 2714 */ 2715 if (preempt_count()) 2716 return; 2717 2718 down_read(&mm->mmap_sem); 2719 vma = find_vma(mm, ip); 2720 if (vma && vma->vm_file) { 2721 struct file *f = vma->vm_file; 2722 char *buf = (char *)__get_free_page(GFP_KERNEL); 2723 if (buf) { 2724 char *p, *s; 2725 2726 p = d_path(&f->f_path, buf, PAGE_SIZE); 2727 if (IS_ERR(p)) 2728 p = "?"; 2729 s = strrchr(p, '/'); 2730 if (s) 2731 p = s+1; 2732 printk("%s%s[%lx+%lx]", prefix, p, 2733 vma->vm_start, 2734 vma->vm_end - vma->vm_start); 2735 free_page((unsigned long)buf); 2736 } 2737 } 2738 up_read(¤t->mm->mmap_sem); 2739 } 2740