memory.c revision 5b23dbe8173c212d6a326e35347b038705603d39
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 54#include <asm/pgalloc.h> 55#include <asm/uaccess.h> 56#include <asm/tlb.h> 57#include <asm/tlbflush.h> 58#include <asm/pgtable.h> 59 60#include <linux/swapops.h> 61#include <linux/elf.h> 62 63#ifndef CONFIG_NEED_MULTIPLE_NODES 64/* use the per-pgdat data instead for discontigmem - mbligh */ 65unsigned long max_mapnr; 66struct page *mem_map; 67 68EXPORT_SYMBOL(max_mapnr); 69EXPORT_SYMBOL(mem_map); 70#endif 71 72unsigned long num_physpages; 73/* 74 * A number of key systems in x86 including ioremap() rely on the assumption 75 * that high_memory defines the upper bound on direct map memory, then end 76 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 77 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 78 * and ZONE_HIGHMEM. 79 */ 80void * high_memory; 81 82EXPORT_SYMBOL(num_physpages); 83EXPORT_SYMBOL(high_memory); 84 85int randomize_va_space __read_mostly = 1; 86 87static int __init disable_randmaps(char *s) 88{ 89 randomize_va_space = 0; 90 return 1; 91} 92__setup("norandmaps", disable_randmaps); 93 94 95/* 96 * If a p?d_bad entry is found while walking page tables, report 97 * the error, before resetting entry to p?d_none. Usually (but 98 * very seldom) called out from the p?d_none_or_clear_bad macros. 99 */ 100 101void pgd_clear_bad(pgd_t *pgd) 102{ 103 pgd_ERROR(*pgd); 104 pgd_clear(pgd); 105} 106 107void pud_clear_bad(pud_t *pud) 108{ 109 pud_ERROR(*pud); 110 pud_clear(pud); 111} 112 113void pmd_clear_bad(pmd_t *pmd) 114{ 115 pmd_ERROR(*pmd); 116 pmd_clear(pmd); 117} 118 119/* 120 * Note: this doesn't free the actual pages themselves. That 121 * has been handled earlier when unmapping all the memory regions. 122 */ 123static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd) 124{ 125 struct page *page = pmd_page(*pmd); 126 pmd_clear(pmd); 127 pte_lock_deinit(page); 128 pte_free_tlb(tlb, page); 129 dec_zone_page_state(page, NR_PAGETABLE); 130 tlb->mm->nr_ptes--; 131} 132 133static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 134 unsigned long addr, unsigned long end, 135 unsigned long floor, unsigned long ceiling) 136{ 137 pmd_t *pmd; 138 unsigned long next; 139 unsigned long start; 140 141 start = addr; 142 pmd = pmd_offset(pud, addr); 143 do { 144 next = pmd_addr_end(addr, end); 145 if (pmd_none_or_clear_bad(pmd)) 146 continue; 147 free_pte_range(tlb, pmd); 148 } while (pmd++, addr = next, addr != end); 149 150 start &= PUD_MASK; 151 if (start < floor) 152 return; 153 if (ceiling) { 154 ceiling &= PUD_MASK; 155 if (!ceiling) 156 return; 157 } 158 if (end - 1 > ceiling - 1) 159 return; 160 161 pmd = pmd_offset(pud, start); 162 pud_clear(pud); 163 pmd_free_tlb(tlb, pmd); 164} 165 166static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 167 unsigned long addr, unsigned long end, 168 unsigned long floor, unsigned long ceiling) 169{ 170 pud_t *pud; 171 unsigned long next; 172 unsigned long start; 173 174 start = addr; 175 pud = pud_offset(pgd, addr); 176 do { 177 next = pud_addr_end(addr, end); 178 if (pud_none_or_clear_bad(pud)) 179 continue; 180 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 181 } while (pud++, addr = next, addr != end); 182 183 start &= PGDIR_MASK; 184 if (start < floor) 185 return; 186 if (ceiling) { 187 ceiling &= PGDIR_MASK; 188 if (!ceiling) 189 return; 190 } 191 if (end - 1 > ceiling - 1) 192 return; 193 194 pud = pud_offset(pgd, start); 195 pgd_clear(pgd); 196 pud_free_tlb(tlb, pud); 197} 198 199/* 200 * This function frees user-level page tables of a process. 201 * 202 * Must be called with pagetable lock held. 203 */ 204void free_pgd_range(struct mmu_gather **tlb, 205 unsigned long addr, unsigned long end, 206 unsigned long floor, unsigned long ceiling) 207{ 208 pgd_t *pgd; 209 unsigned long next; 210 unsigned long start; 211 212 /* 213 * The next few lines have given us lots of grief... 214 * 215 * Why are we testing PMD* at this top level? Because often 216 * there will be no work to do at all, and we'd prefer not to 217 * go all the way down to the bottom just to discover that. 218 * 219 * Why all these "- 1"s? Because 0 represents both the bottom 220 * of the address space and the top of it (using -1 for the 221 * top wouldn't help much: the masks would do the wrong thing). 222 * The rule is that addr 0 and floor 0 refer to the bottom of 223 * the address space, but end 0 and ceiling 0 refer to the top 224 * Comparisons need to use "end - 1" and "ceiling - 1" (though 225 * that end 0 case should be mythical). 226 * 227 * Wherever addr is brought up or ceiling brought down, we must 228 * be careful to reject "the opposite 0" before it confuses the 229 * subsequent tests. But what about where end is brought down 230 * by PMD_SIZE below? no, end can't go down to 0 there. 231 * 232 * Whereas we round start (addr) and ceiling down, by different 233 * masks at different levels, in order to test whether a table 234 * now has no other vmas using it, so can be freed, we don't 235 * bother to round floor or end up - the tests don't need that. 236 */ 237 238 addr &= PMD_MASK; 239 if (addr < floor) { 240 addr += PMD_SIZE; 241 if (!addr) 242 return; 243 } 244 if (ceiling) { 245 ceiling &= PMD_MASK; 246 if (!ceiling) 247 return; 248 } 249 if (end - 1 > ceiling - 1) 250 end -= PMD_SIZE; 251 if (addr > end - 1) 252 return; 253 254 start = addr; 255 pgd = pgd_offset((*tlb)->mm, addr); 256 do { 257 next = pgd_addr_end(addr, end); 258 if (pgd_none_or_clear_bad(pgd)) 259 continue; 260 free_pud_range(*tlb, pgd, addr, next, floor, ceiling); 261 } while (pgd++, addr = next, addr != end); 262} 263 264void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma, 265 unsigned long floor, unsigned long ceiling) 266{ 267 while (vma) { 268 struct vm_area_struct *next = vma->vm_next; 269 unsigned long addr = vma->vm_start; 270 271 /* 272 * Hide vma from rmap and vmtruncate before freeing pgtables 273 */ 274 anon_vma_unlink(vma); 275 unlink_file_vma(vma); 276 277 if (is_vm_hugetlb_page(vma)) { 278 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 279 floor, next? next->vm_start: ceiling); 280 } else { 281 /* 282 * Optimization: gather nearby vmas into one call down 283 */ 284 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 285 && !is_vm_hugetlb_page(next)) { 286 vma = next; 287 next = vma->vm_next; 288 anon_vma_unlink(vma); 289 unlink_file_vma(vma); 290 } 291 free_pgd_range(tlb, addr, vma->vm_end, 292 floor, next? next->vm_start: ceiling); 293 } 294 vma = next; 295 } 296} 297 298int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 299{ 300 struct page *new = pte_alloc_one(mm, address); 301 if (!new) 302 return -ENOMEM; 303 304 pte_lock_init(new); 305 spin_lock(&mm->page_table_lock); 306 if (pmd_present(*pmd)) { /* Another has populated it */ 307 pte_lock_deinit(new); 308 pte_free(new); 309 } else { 310 mm->nr_ptes++; 311 inc_zone_page_state(new, NR_PAGETABLE); 312 pmd_populate(mm, pmd, new); 313 } 314 spin_unlock(&mm->page_table_lock); 315 return 0; 316} 317 318int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 319{ 320 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 321 if (!new) 322 return -ENOMEM; 323 324 spin_lock(&init_mm.page_table_lock); 325 if (pmd_present(*pmd)) /* Another has populated it */ 326 pte_free_kernel(new); 327 else 328 pmd_populate_kernel(&init_mm, pmd, new); 329 spin_unlock(&init_mm.page_table_lock); 330 return 0; 331} 332 333static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) 334{ 335 if (file_rss) 336 add_mm_counter(mm, file_rss, file_rss); 337 if (anon_rss) 338 add_mm_counter(mm, anon_rss, anon_rss); 339} 340 341/* 342 * This function is called to print an error when a bad pte 343 * is found. For example, we might have a PFN-mapped pte in 344 * a region that doesn't allow it. 345 * 346 * The calling function must still handle the error. 347 */ 348void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr) 349{ 350 printk(KERN_ERR "Bad pte = %08llx, process = %s, " 351 "vm_flags = %lx, vaddr = %lx\n", 352 (long long)pte_val(pte), 353 (vma->vm_mm == current->mm ? current->comm : "???"), 354 vma->vm_flags, vaddr); 355 dump_stack(); 356} 357 358static inline int is_cow_mapping(unsigned int flags) 359{ 360 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 361} 362 363/* 364 * This function gets the "struct page" associated with a pte. 365 * 366 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping 367 * will have each page table entry just pointing to a raw page frame 368 * number, and as far as the VM layer is concerned, those do not have 369 * pages associated with them - even if the PFN might point to memory 370 * that otherwise is perfectly fine and has a "struct page". 371 * 372 * The way we recognize those mappings is through the rules set up 373 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set, 374 * and the vm_pgoff will point to the first PFN mapped: thus every 375 * page that is a raw mapping will always honor the rule 376 * 377 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 378 * 379 * and if that isn't true, the page has been COW'ed (in which case it 380 * _does_ have a "struct page" associated with it even if it is in a 381 * VM_PFNMAP range). 382 */ 383struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte) 384{ 385 unsigned long pfn = pte_pfn(pte); 386 387 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 388 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT; 389 if (pfn == vma->vm_pgoff + off) 390 return NULL; 391 if (!is_cow_mapping(vma->vm_flags)) 392 return NULL; 393 } 394 395 /* 396 * Add some anal sanity checks for now. Eventually, 397 * we should just do "return pfn_to_page(pfn)", but 398 * in the meantime we check that we get a valid pfn, 399 * and that the resulting page looks ok. 400 */ 401 if (unlikely(!pfn_valid(pfn))) { 402 print_bad_pte(vma, pte, addr); 403 return NULL; 404 } 405 406 /* 407 * NOTE! We still have PageReserved() pages in the page 408 * tables. 409 * 410 * The PAGE_ZERO() pages and various VDSO mappings can 411 * cause them to exist. 412 */ 413 return pfn_to_page(pfn); 414} 415 416/* 417 * copy one vm_area from one task to the other. Assumes the page tables 418 * already present in the new task to be cleared in the whole range 419 * covered by this vma. 420 */ 421 422static inline void 423copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 424 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 425 unsigned long addr, int *rss) 426{ 427 unsigned long vm_flags = vma->vm_flags; 428 pte_t pte = *src_pte; 429 struct page *page; 430 431 /* pte contains position in swap or file, so copy. */ 432 if (unlikely(!pte_present(pte))) { 433 if (!pte_file(pte)) { 434 swp_entry_t entry = pte_to_swp_entry(pte); 435 436 swap_duplicate(entry); 437 /* make sure dst_mm is on swapoff's mmlist. */ 438 if (unlikely(list_empty(&dst_mm->mmlist))) { 439 spin_lock(&mmlist_lock); 440 if (list_empty(&dst_mm->mmlist)) 441 list_add(&dst_mm->mmlist, 442 &src_mm->mmlist); 443 spin_unlock(&mmlist_lock); 444 } 445 if (is_write_migration_entry(entry) && 446 is_cow_mapping(vm_flags)) { 447 /* 448 * COW mappings require pages in both parent 449 * and child to be set to read. 450 */ 451 make_migration_entry_read(&entry); 452 pte = swp_entry_to_pte(entry); 453 set_pte_at(src_mm, addr, src_pte, pte); 454 } 455 } 456 goto out_set_pte; 457 } 458 459 /* 460 * If it's a COW mapping, write protect it both 461 * in the parent and the child 462 */ 463 if (is_cow_mapping(vm_flags)) { 464 ptep_set_wrprotect(src_mm, addr, src_pte); 465 pte = pte_wrprotect(pte); 466 } 467 468 /* 469 * If it's a shared mapping, mark it clean in 470 * the child 471 */ 472 if (vm_flags & VM_SHARED) 473 pte = pte_mkclean(pte); 474 pte = pte_mkold(pte); 475 476 page = vm_normal_page(vma, addr, pte); 477 if (page) { 478 get_page(page); 479 page_dup_rmap(page, vma, addr); 480 rss[!!PageAnon(page)]++; 481 } 482 483out_set_pte: 484 set_pte_at(dst_mm, addr, dst_pte, pte); 485} 486 487static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 488 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 489 unsigned long addr, unsigned long end) 490{ 491 pte_t *src_pte, *dst_pte; 492 spinlock_t *src_ptl, *dst_ptl; 493 int progress = 0; 494 int rss[2]; 495 496again: 497 rss[1] = rss[0] = 0; 498 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 499 if (!dst_pte) 500 return -ENOMEM; 501 src_pte = pte_offset_map_nested(src_pmd, addr); 502 src_ptl = pte_lockptr(src_mm, src_pmd); 503 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 504 arch_enter_lazy_mmu_mode(); 505 506 do { 507 /* 508 * We are holding two locks at this point - either of them 509 * could generate latencies in another task on another CPU. 510 */ 511 if (progress >= 32) { 512 progress = 0; 513 if (need_resched() || 514 need_lockbreak(src_ptl) || 515 need_lockbreak(dst_ptl)) 516 break; 517 } 518 if (pte_none(*src_pte)) { 519 progress++; 520 continue; 521 } 522 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 523 progress += 8; 524 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 525 526 arch_leave_lazy_mmu_mode(); 527 spin_unlock(src_ptl); 528 pte_unmap_nested(src_pte - 1); 529 add_mm_rss(dst_mm, rss[0], rss[1]); 530 pte_unmap_unlock(dst_pte - 1, dst_ptl); 531 cond_resched(); 532 if (addr != end) 533 goto again; 534 return 0; 535} 536 537static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 538 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 539 unsigned long addr, unsigned long end) 540{ 541 pmd_t *src_pmd, *dst_pmd; 542 unsigned long next; 543 544 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 545 if (!dst_pmd) 546 return -ENOMEM; 547 src_pmd = pmd_offset(src_pud, addr); 548 do { 549 next = pmd_addr_end(addr, end); 550 if (pmd_none_or_clear_bad(src_pmd)) 551 continue; 552 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 553 vma, addr, next)) 554 return -ENOMEM; 555 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 556 return 0; 557} 558 559static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 560 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 561 unsigned long addr, unsigned long end) 562{ 563 pud_t *src_pud, *dst_pud; 564 unsigned long next; 565 566 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 567 if (!dst_pud) 568 return -ENOMEM; 569 src_pud = pud_offset(src_pgd, addr); 570 do { 571 next = pud_addr_end(addr, end); 572 if (pud_none_or_clear_bad(src_pud)) 573 continue; 574 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 575 vma, addr, next)) 576 return -ENOMEM; 577 } while (dst_pud++, src_pud++, addr = next, addr != end); 578 return 0; 579} 580 581int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 582 struct vm_area_struct *vma) 583{ 584 pgd_t *src_pgd, *dst_pgd; 585 unsigned long next; 586 unsigned long addr = vma->vm_start; 587 unsigned long end = vma->vm_end; 588 589 /* 590 * Don't copy ptes where a page fault will fill them correctly. 591 * Fork becomes much lighter when there are big shared or private 592 * readonly mappings. The tradeoff is that copy_page_range is more 593 * efficient than faulting. 594 */ 595 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 596 if (!vma->anon_vma) 597 return 0; 598 } 599 600 if (is_vm_hugetlb_page(vma)) 601 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 602 603 dst_pgd = pgd_offset(dst_mm, addr); 604 src_pgd = pgd_offset(src_mm, addr); 605 do { 606 next = pgd_addr_end(addr, end); 607 if (pgd_none_or_clear_bad(src_pgd)) 608 continue; 609 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 610 vma, addr, next)) 611 return -ENOMEM; 612 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 613 return 0; 614} 615 616static unsigned long zap_pte_range(struct mmu_gather *tlb, 617 struct vm_area_struct *vma, pmd_t *pmd, 618 unsigned long addr, unsigned long end, 619 long *zap_work, struct zap_details *details) 620{ 621 struct mm_struct *mm = tlb->mm; 622 pte_t *pte; 623 spinlock_t *ptl; 624 int file_rss = 0; 625 int anon_rss = 0; 626 627 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 628 arch_enter_lazy_mmu_mode(); 629 do { 630 pte_t ptent = *pte; 631 if (pte_none(ptent)) { 632 (*zap_work)--; 633 continue; 634 } 635 636 (*zap_work) -= PAGE_SIZE; 637 638 if (pte_present(ptent)) { 639 struct page *page; 640 641 page = vm_normal_page(vma, addr, ptent); 642 if (unlikely(details) && page) { 643 /* 644 * unmap_shared_mapping_pages() wants to 645 * invalidate cache without truncating: 646 * unmap shared but keep private pages. 647 */ 648 if (details->check_mapping && 649 details->check_mapping != page->mapping) 650 continue; 651 /* 652 * Each page->index must be checked when 653 * invalidating or truncating nonlinear. 654 */ 655 if (details->nonlinear_vma && 656 (page->index < details->first_index || 657 page->index > details->last_index)) 658 continue; 659 } 660 ptent = ptep_get_and_clear_full(mm, addr, pte, 661 tlb->fullmm); 662 tlb_remove_tlb_entry(tlb, pte, addr); 663 if (unlikely(!page)) 664 continue; 665 if (unlikely(details) && details->nonlinear_vma 666 && linear_page_index(details->nonlinear_vma, 667 addr) != page->index) 668 set_pte_at(mm, addr, pte, 669 pgoff_to_pte(page->index)); 670 if (PageAnon(page)) 671 anon_rss--; 672 else { 673 if (pte_dirty(ptent)) 674 set_page_dirty(page); 675 if (pte_young(ptent)) 676 SetPageReferenced(page); 677 file_rss--; 678 } 679 page_remove_rmap(page, vma); 680 tlb_remove_page(tlb, page); 681 continue; 682 } 683 /* 684 * If details->check_mapping, we leave swap entries; 685 * if details->nonlinear_vma, we leave file entries. 686 */ 687 if (unlikely(details)) 688 continue; 689 if (!pte_file(ptent)) 690 free_swap_and_cache(pte_to_swp_entry(ptent)); 691 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 692 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 693 694 add_mm_rss(mm, file_rss, anon_rss); 695 arch_leave_lazy_mmu_mode(); 696 pte_unmap_unlock(pte - 1, ptl); 697 698 return addr; 699} 700 701static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 702 struct vm_area_struct *vma, pud_t *pud, 703 unsigned long addr, unsigned long end, 704 long *zap_work, struct zap_details *details) 705{ 706 pmd_t *pmd; 707 unsigned long next; 708 709 pmd = pmd_offset(pud, addr); 710 do { 711 next = pmd_addr_end(addr, end); 712 if (pmd_none_or_clear_bad(pmd)) { 713 (*zap_work)--; 714 continue; 715 } 716 next = zap_pte_range(tlb, vma, pmd, addr, next, 717 zap_work, details); 718 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 719 720 return addr; 721} 722 723static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 724 struct vm_area_struct *vma, pgd_t *pgd, 725 unsigned long addr, unsigned long end, 726 long *zap_work, struct zap_details *details) 727{ 728 pud_t *pud; 729 unsigned long next; 730 731 pud = pud_offset(pgd, addr); 732 do { 733 next = pud_addr_end(addr, end); 734 if (pud_none_or_clear_bad(pud)) { 735 (*zap_work)--; 736 continue; 737 } 738 next = zap_pmd_range(tlb, vma, pud, addr, next, 739 zap_work, details); 740 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 741 742 return addr; 743} 744 745static unsigned long unmap_page_range(struct mmu_gather *tlb, 746 struct vm_area_struct *vma, 747 unsigned long addr, unsigned long end, 748 long *zap_work, struct zap_details *details) 749{ 750 pgd_t *pgd; 751 unsigned long next; 752 753 if (details && !details->check_mapping && !details->nonlinear_vma) 754 details = NULL; 755 756 BUG_ON(addr >= end); 757 tlb_start_vma(tlb, vma); 758 pgd = pgd_offset(vma->vm_mm, addr); 759 do { 760 next = pgd_addr_end(addr, end); 761 if (pgd_none_or_clear_bad(pgd)) { 762 (*zap_work)--; 763 continue; 764 } 765 next = zap_pud_range(tlb, vma, pgd, addr, next, 766 zap_work, details); 767 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 768 tlb_end_vma(tlb, vma); 769 770 return addr; 771} 772 773#ifdef CONFIG_PREEMPT 774# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 775#else 776/* No preempt: go for improved straight-line efficiency */ 777# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 778#endif 779 780/** 781 * unmap_vmas - unmap a range of memory covered by a list of vma's 782 * @tlbp: address of the caller's struct mmu_gather 783 * @vma: the starting vma 784 * @start_addr: virtual address at which to start unmapping 785 * @end_addr: virtual address at which to end unmapping 786 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 787 * @details: details of nonlinear truncation or shared cache invalidation 788 * 789 * Returns the end address of the unmapping (restart addr if interrupted). 790 * 791 * Unmap all pages in the vma list. 792 * 793 * We aim to not hold locks for too long (for scheduling latency reasons). 794 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 795 * return the ending mmu_gather to the caller. 796 * 797 * Only addresses between `start' and `end' will be unmapped. 798 * 799 * The VMA list must be sorted in ascending virtual address order. 800 * 801 * unmap_vmas() assumes that the caller will flush the whole unmapped address 802 * range after unmap_vmas() returns. So the only responsibility here is to 803 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 804 * drops the lock and schedules. 805 */ 806unsigned long unmap_vmas(struct mmu_gather **tlbp, 807 struct vm_area_struct *vma, unsigned long start_addr, 808 unsigned long end_addr, unsigned long *nr_accounted, 809 struct zap_details *details) 810{ 811 long zap_work = ZAP_BLOCK_SIZE; 812 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 813 int tlb_start_valid = 0; 814 unsigned long start = start_addr; 815 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 816 int fullmm = (*tlbp)->fullmm; 817 818 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 819 unsigned long end; 820 821 start = max(vma->vm_start, start_addr); 822 if (start >= vma->vm_end) 823 continue; 824 end = min(vma->vm_end, end_addr); 825 if (end <= vma->vm_start) 826 continue; 827 828 if (vma->vm_flags & VM_ACCOUNT) 829 *nr_accounted += (end - start) >> PAGE_SHIFT; 830 831 while (start != end) { 832 if (!tlb_start_valid) { 833 tlb_start = start; 834 tlb_start_valid = 1; 835 } 836 837 if (unlikely(is_vm_hugetlb_page(vma))) { 838 unmap_hugepage_range(vma, start, end); 839 zap_work -= (end - start) / 840 (HPAGE_SIZE / PAGE_SIZE); 841 start = end; 842 } else 843 start = unmap_page_range(*tlbp, vma, 844 start, end, &zap_work, details); 845 846 if (zap_work > 0) { 847 BUG_ON(start != end); 848 break; 849 } 850 851 tlb_finish_mmu(*tlbp, tlb_start, start); 852 853 if (need_resched() || 854 (i_mmap_lock && need_lockbreak(i_mmap_lock))) { 855 if (i_mmap_lock) { 856 *tlbp = NULL; 857 goto out; 858 } 859 cond_resched(); 860 } 861 862 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 863 tlb_start_valid = 0; 864 zap_work = ZAP_BLOCK_SIZE; 865 } 866 } 867out: 868 return start; /* which is now the end (or restart) address */ 869} 870 871/** 872 * zap_page_range - remove user pages in a given range 873 * @vma: vm_area_struct holding the applicable pages 874 * @address: starting address of pages to zap 875 * @size: number of bytes to zap 876 * @details: details of nonlinear truncation or shared cache invalidation 877 */ 878unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 879 unsigned long size, struct zap_details *details) 880{ 881 struct mm_struct *mm = vma->vm_mm; 882 struct mmu_gather *tlb; 883 unsigned long end = address + size; 884 unsigned long nr_accounted = 0; 885 886 lru_add_drain(); 887 tlb = tlb_gather_mmu(mm, 0); 888 update_hiwater_rss(mm); 889 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 890 if (tlb) 891 tlb_finish_mmu(tlb, address, end); 892 return end; 893} 894 895/* 896 * Do a quick page-table lookup for a single page. 897 */ 898struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 899 unsigned int flags) 900{ 901 pgd_t *pgd; 902 pud_t *pud; 903 pmd_t *pmd; 904 pte_t *ptep, pte; 905 spinlock_t *ptl; 906 struct page *page; 907 struct mm_struct *mm = vma->vm_mm; 908 909 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 910 if (!IS_ERR(page)) { 911 BUG_ON(flags & FOLL_GET); 912 goto out; 913 } 914 915 page = NULL; 916 pgd = pgd_offset(mm, address); 917 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 918 goto no_page_table; 919 920 pud = pud_offset(pgd, address); 921 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 922 goto no_page_table; 923 924 pmd = pmd_offset(pud, address); 925 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 926 goto no_page_table; 927 928 if (pmd_huge(*pmd)) { 929 BUG_ON(flags & FOLL_GET); 930 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 931 goto out; 932 } 933 934 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 935 if (!ptep) 936 goto out; 937 938 pte = *ptep; 939 if (!pte_present(pte)) 940 goto unlock; 941 if ((flags & FOLL_WRITE) && !pte_write(pte)) 942 goto unlock; 943 page = vm_normal_page(vma, address, pte); 944 if (unlikely(!page)) 945 goto unlock; 946 947 if (flags & FOLL_GET) 948 get_page(page); 949 if (flags & FOLL_TOUCH) { 950 if ((flags & FOLL_WRITE) && 951 !pte_dirty(pte) && !PageDirty(page)) 952 set_page_dirty(page); 953 mark_page_accessed(page); 954 } 955unlock: 956 pte_unmap_unlock(ptep, ptl); 957out: 958 return page; 959 960no_page_table: 961 /* 962 * When core dumping an enormous anonymous area that nobody 963 * has touched so far, we don't want to allocate page tables. 964 */ 965 if (flags & FOLL_ANON) { 966 page = ZERO_PAGE(0); 967 if (flags & FOLL_GET) 968 get_page(page); 969 BUG_ON(flags & FOLL_WRITE); 970 } 971 return page; 972} 973 974int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 975 unsigned long start, int len, int write, int force, 976 struct page **pages, struct vm_area_struct **vmas) 977{ 978 int i; 979 unsigned int vm_flags; 980 981 /* 982 * Require read or write permissions. 983 * If 'force' is set, we only require the "MAY" flags. 984 */ 985 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 986 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 987 i = 0; 988 989 do { 990 struct vm_area_struct *vma; 991 unsigned int foll_flags; 992 993 vma = find_extend_vma(mm, start); 994 if (!vma && in_gate_area(tsk, start)) { 995 unsigned long pg = start & PAGE_MASK; 996 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 997 pgd_t *pgd; 998 pud_t *pud; 999 pmd_t *pmd; 1000 pte_t *pte; 1001 if (write) /* user gate pages are read-only */ 1002 return i ? : -EFAULT; 1003 if (pg > TASK_SIZE) 1004 pgd = pgd_offset_k(pg); 1005 else 1006 pgd = pgd_offset_gate(mm, pg); 1007 BUG_ON(pgd_none(*pgd)); 1008 pud = pud_offset(pgd, pg); 1009 BUG_ON(pud_none(*pud)); 1010 pmd = pmd_offset(pud, pg); 1011 if (pmd_none(*pmd)) 1012 return i ? : -EFAULT; 1013 pte = pte_offset_map(pmd, pg); 1014 if (pte_none(*pte)) { 1015 pte_unmap(pte); 1016 return i ? : -EFAULT; 1017 } 1018 if (pages) { 1019 struct page *page = vm_normal_page(gate_vma, start, *pte); 1020 pages[i] = page; 1021 if (page) 1022 get_page(page); 1023 } 1024 pte_unmap(pte); 1025 if (vmas) 1026 vmas[i] = gate_vma; 1027 i++; 1028 start += PAGE_SIZE; 1029 len--; 1030 continue; 1031 } 1032 1033 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP)) 1034 || !(vm_flags & vma->vm_flags)) 1035 return i ? : -EFAULT; 1036 1037 if (is_vm_hugetlb_page(vma)) { 1038 i = follow_hugetlb_page(mm, vma, pages, vmas, 1039 &start, &len, i, write); 1040 continue; 1041 } 1042 1043 foll_flags = FOLL_TOUCH; 1044 if (pages) 1045 foll_flags |= FOLL_GET; 1046 if (!write && !(vma->vm_flags & VM_LOCKED) && 1047 (!vma->vm_ops || (!vma->vm_ops->nopage && 1048 !vma->vm_ops->fault))) 1049 foll_flags |= FOLL_ANON; 1050 1051 do { 1052 struct page *page; 1053 1054 /* 1055 * If tsk is ooming, cut off its access to large memory 1056 * allocations. It has a pending SIGKILL, but it can't 1057 * be processed until returning to user space. 1058 */ 1059 if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE))) 1060 return -ENOMEM; 1061 1062 if (write) 1063 foll_flags |= FOLL_WRITE; 1064 1065 cond_resched(); 1066 while (!(page = follow_page(vma, start, foll_flags))) { 1067 int ret; 1068 ret = handle_mm_fault(mm, vma, start, 1069 foll_flags & FOLL_WRITE); 1070 if (ret & VM_FAULT_ERROR) { 1071 if (ret & VM_FAULT_OOM) 1072 return i ? i : -ENOMEM; 1073 else if (ret & VM_FAULT_SIGBUS) 1074 return i ? i : -EFAULT; 1075 BUG(); 1076 } 1077 if (ret & VM_FAULT_MAJOR) 1078 tsk->maj_flt++; 1079 else 1080 tsk->min_flt++; 1081 1082 /* 1083 * The VM_FAULT_WRITE bit tells us that 1084 * do_wp_page has broken COW when necessary, 1085 * even if maybe_mkwrite decided not to set 1086 * pte_write. We can thus safely do subsequent 1087 * page lookups as if they were reads. 1088 */ 1089 if (ret & VM_FAULT_WRITE) 1090 foll_flags &= ~FOLL_WRITE; 1091 1092 cond_resched(); 1093 } 1094 if (pages) { 1095 pages[i] = page; 1096 1097 flush_anon_page(vma, page, start); 1098 flush_dcache_page(page); 1099 } 1100 if (vmas) 1101 vmas[i] = vma; 1102 i++; 1103 start += PAGE_SIZE; 1104 len--; 1105 } while (len && start < vma->vm_end); 1106 } while (len); 1107 return i; 1108} 1109EXPORT_SYMBOL(get_user_pages); 1110 1111pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl) 1112{ 1113 pgd_t * pgd = pgd_offset(mm, addr); 1114 pud_t * pud = pud_alloc(mm, pgd, addr); 1115 if (pud) { 1116 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1117 if (pmd) 1118 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1119 } 1120 return NULL; 1121} 1122 1123/* 1124 * This is the old fallback for page remapping. 1125 * 1126 * For historical reasons, it only allows reserved pages. Only 1127 * old drivers should use this, and they needed to mark their 1128 * pages reserved for the old functions anyway. 1129 */ 1130static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot) 1131{ 1132 int retval; 1133 pte_t *pte; 1134 spinlock_t *ptl; 1135 1136 retval = -EINVAL; 1137 if (PageAnon(page)) 1138 goto out; 1139 retval = -ENOMEM; 1140 flush_dcache_page(page); 1141 pte = get_locked_pte(mm, addr, &ptl); 1142 if (!pte) 1143 goto out; 1144 retval = -EBUSY; 1145 if (!pte_none(*pte)) 1146 goto out_unlock; 1147 1148 /* Ok, finally just insert the thing.. */ 1149 get_page(page); 1150 inc_mm_counter(mm, file_rss); 1151 page_add_file_rmap(page); 1152 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1153 1154 retval = 0; 1155out_unlock: 1156 pte_unmap_unlock(pte, ptl); 1157out: 1158 return retval; 1159} 1160 1161/** 1162 * vm_insert_page - insert single page into user vma 1163 * @vma: user vma to map to 1164 * @addr: target user address of this page 1165 * @page: source kernel page 1166 * 1167 * This allows drivers to insert individual pages they've allocated 1168 * into a user vma. 1169 * 1170 * The page has to be a nice clean _individual_ kernel allocation. 1171 * If you allocate a compound page, you need to have marked it as 1172 * such (__GFP_COMP), or manually just split the page up yourself 1173 * (see split_page()). 1174 * 1175 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1176 * took an arbitrary page protection parameter. This doesn't allow 1177 * that. Your vma protection will have to be set up correctly, which 1178 * means that if you want a shared writable mapping, you'd better 1179 * ask for a shared writable mapping! 1180 * 1181 * The page does not need to be reserved. 1182 */ 1183int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page) 1184{ 1185 if (addr < vma->vm_start || addr >= vma->vm_end) 1186 return -EFAULT; 1187 if (!page_count(page)) 1188 return -EINVAL; 1189 vma->vm_flags |= VM_INSERTPAGE; 1190 return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot); 1191} 1192EXPORT_SYMBOL(vm_insert_page); 1193 1194/** 1195 * vm_insert_pfn - insert single pfn into user vma 1196 * @vma: user vma to map to 1197 * @addr: target user address of this page 1198 * @pfn: source kernel pfn 1199 * 1200 * Similar to vm_inert_page, this allows drivers to insert individual pages 1201 * they've allocated into a user vma. Same comments apply. 1202 * 1203 * This function should only be called from a vm_ops->fault handler, and 1204 * in that case the handler should return NULL. 1205 */ 1206int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1207 unsigned long pfn) 1208{ 1209 struct mm_struct *mm = vma->vm_mm; 1210 int retval; 1211 pte_t *pte, entry; 1212 spinlock_t *ptl; 1213 1214 BUG_ON(!(vma->vm_flags & VM_PFNMAP)); 1215 BUG_ON(is_cow_mapping(vma->vm_flags)); 1216 1217 retval = -ENOMEM; 1218 pte = get_locked_pte(mm, addr, &ptl); 1219 if (!pte) 1220 goto out; 1221 retval = -EBUSY; 1222 if (!pte_none(*pte)) 1223 goto out_unlock; 1224 1225 /* Ok, finally just insert the thing.. */ 1226 entry = pfn_pte(pfn, vma->vm_page_prot); 1227 set_pte_at(mm, addr, pte, entry); 1228 update_mmu_cache(vma, addr, entry); 1229 1230 retval = 0; 1231out_unlock: 1232 pte_unmap_unlock(pte, ptl); 1233 1234out: 1235 return retval; 1236} 1237EXPORT_SYMBOL(vm_insert_pfn); 1238 1239/* 1240 * maps a range of physical memory into the requested pages. the old 1241 * mappings are removed. any references to nonexistent pages results 1242 * in null mappings (currently treated as "copy-on-access") 1243 */ 1244static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1245 unsigned long addr, unsigned long end, 1246 unsigned long pfn, pgprot_t prot) 1247{ 1248 pte_t *pte; 1249 spinlock_t *ptl; 1250 1251 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1252 if (!pte) 1253 return -ENOMEM; 1254 arch_enter_lazy_mmu_mode(); 1255 do { 1256 BUG_ON(!pte_none(*pte)); 1257 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); 1258 pfn++; 1259 } while (pte++, addr += PAGE_SIZE, addr != end); 1260 arch_leave_lazy_mmu_mode(); 1261 pte_unmap_unlock(pte - 1, ptl); 1262 return 0; 1263} 1264 1265static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1266 unsigned long addr, unsigned long end, 1267 unsigned long pfn, pgprot_t prot) 1268{ 1269 pmd_t *pmd; 1270 unsigned long next; 1271 1272 pfn -= addr >> PAGE_SHIFT; 1273 pmd = pmd_alloc(mm, pud, addr); 1274 if (!pmd) 1275 return -ENOMEM; 1276 do { 1277 next = pmd_addr_end(addr, end); 1278 if (remap_pte_range(mm, pmd, addr, next, 1279 pfn + (addr >> PAGE_SHIFT), prot)) 1280 return -ENOMEM; 1281 } while (pmd++, addr = next, addr != end); 1282 return 0; 1283} 1284 1285static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1286 unsigned long addr, unsigned long end, 1287 unsigned long pfn, pgprot_t prot) 1288{ 1289 pud_t *pud; 1290 unsigned long next; 1291 1292 pfn -= addr >> PAGE_SHIFT; 1293 pud = pud_alloc(mm, pgd, addr); 1294 if (!pud) 1295 return -ENOMEM; 1296 do { 1297 next = pud_addr_end(addr, end); 1298 if (remap_pmd_range(mm, pud, addr, next, 1299 pfn + (addr >> PAGE_SHIFT), prot)) 1300 return -ENOMEM; 1301 } while (pud++, addr = next, addr != end); 1302 return 0; 1303} 1304 1305/** 1306 * remap_pfn_range - remap kernel memory to userspace 1307 * @vma: user vma to map to 1308 * @addr: target user address to start at 1309 * @pfn: physical address of kernel memory 1310 * @size: size of map area 1311 * @prot: page protection flags for this mapping 1312 * 1313 * Note: this is only safe if the mm semaphore is held when called. 1314 */ 1315int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1316 unsigned long pfn, unsigned long size, pgprot_t prot) 1317{ 1318 pgd_t *pgd; 1319 unsigned long next; 1320 unsigned long end = addr + PAGE_ALIGN(size); 1321 struct mm_struct *mm = vma->vm_mm; 1322 int err; 1323 1324 /* 1325 * Physically remapped pages are special. Tell the 1326 * rest of the world about it: 1327 * VM_IO tells people not to look at these pages 1328 * (accesses can have side effects). 1329 * VM_RESERVED is specified all over the place, because 1330 * in 2.4 it kept swapout's vma scan off this vma; but 1331 * in 2.6 the LRU scan won't even find its pages, so this 1332 * flag means no more than count its pages in reserved_vm, 1333 * and omit it from core dump, even when VM_IO turned off. 1334 * VM_PFNMAP tells the core MM that the base pages are just 1335 * raw PFN mappings, and do not have a "struct page" associated 1336 * with them. 1337 * 1338 * There's a horrible special case to handle copy-on-write 1339 * behaviour that some programs depend on. We mark the "original" 1340 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1341 */ 1342 if (is_cow_mapping(vma->vm_flags)) { 1343 if (addr != vma->vm_start || end != vma->vm_end) 1344 return -EINVAL; 1345 vma->vm_pgoff = pfn; 1346 } 1347 1348 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 1349 1350 BUG_ON(addr >= end); 1351 pfn -= addr >> PAGE_SHIFT; 1352 pgd = pgd_offset(mm, addr); 1353 flush_cache_range(vma, addr, end); 1354 do { 1355 next = pgd_addr_end(addr, end); 1356 err = remap_pud_range(mm, pgd, addr, next, 1357 pfn + (addr >> PAGE_SHIFT), prot); 1358 if (err) 1359 break; 1360 } while (pgd++, addr = next, addr != end); 1361 return err; 1362} 1363EXPORT_SYMBOL(remap_pfn_range); 1364 1365static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 1366 unsigned long addr, unsigned long end, 1367 pte_fn_t fn, void *data) 1368{ 1369 pte_t *pte; 1370 int err; 1371 struct page *pmd_page; 1372 spinlock_t *uninitialized_var(ptl); 1373 1374 pte = (mm == &init_mm) ? 1375 pte_alloc_kernel(pmd, addr) : 1376 pte_alloc_map_lock(mm, pmd, addr, &ptl); 1377 if (!pte) 1378 return -ENOMEM; 1379 1380 BUG_ON(pmd_huge(*pmd)); 1381 1382 pmd_page = pmd_page(*pmd); 1383 1384 do { 1385 err = fn(pte, pmd_page, addr, data); 1386 if (err) 1387 break; 1388 } while (pte++, addr += PAGE_SIZE, addr != end); 1389 1390 if (mm != &init_mm) 1391 pte_unmap_unlock(pte-1, ptl); 1392 return err; 1393} 1394 1395static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 1396 unsigned long addr, unsigned long end, 1397 pte_fn_t fn, void *data) 1398{ 1399 pmd_t *pmd; 1400 unsigned long next; 1401 int err; 1402 1403 pmd = pmd_alloc(mm, pud, addr); 1404 if (!pmd) 1405 return -ENOMEM; 1406 do { 1407 next = pmd_addr_end(addr, end); 1408 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 1409 if (err) 1410 break; 1411 } while (pmd++, addr = next, addr != end); 1412 return err; 1413} 1414 1415static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 1416 unsigned long addr, unsigned long end, 1417 pte_fn_t fn, void *data) 1418{ 1419 pud_t *pud; 1420 unsigned long next; 1421 int err; 1422 1423 pud = pud_alloc(mm, pgd, addr); 1424 if (!pud) 1425 return -ENOMEM; 1426 do { 1427 next = pud_addr_end(addr, end); 1428 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 1429 if (err) 1430 break; 1431 } while (pud++, addr = next, addr != end); 1432 return err; 1433} 1434 1435/* 1436 * Scan a region of virtual memory, filling in page tables as necessary 1437 * and calling a provided function on each leaf page table. 1438 */ 1439int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 1440 unsigned long size, pte_fn_t fn, void *data) 1441{ 1442 pgd_t *pgd; 1443 unsigned long next; 1444 unsigned long end = addr + size; 1445 int err; 1446 1447 BUG_ON(addr >= end); 1448 pgd = pgd_offset(mm, addr); 1449 do { 1450 next = pgd_addr_end(addr, end); 1451 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 1452 if (err) 1453 break; 1454 } while (pgd++, addr = next, addr != end); 1455 return err; 1456} 1457EXPORT_SYMBOL_GPL(apply_to_page_range); 1458 1459/* 1460 * handle_pte_fault chooses page fault handler according to an entry 1461 * which was read non-atomically. Before making any commitment, on 1462 * those architectures or configurations (e.g. i386 with PAE) which 1463 * might give a mix of unmatched parts, do_swap_page and do_file_page 1464 * must check under lock before unmapping the pte and proceeding 1465 * (but do_wp_page is only called after already making such a check; 1466 * and do_anonymous_page and do_no_page can safely check later on). 1467 */ 1468static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1469 pte_t *page_table, pte_t orig_pte) 1470{ 1471 int same = 1; 1472#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1473 if (sizeof(pte_t) > sizeof(unsigned long)) { 1474 spinlock_t *ptl = pte_lockptr(mm, pmd); 1475 spin_lock(ptl); 1476 same = pte_same(*page_table, orig_pte); 1477 spin_unlock(ptl); 1478 } 1479#endif 1480 pte_unmap(page_table); 1481 return same; 1482} 1483 1484/* 1485 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1486 * servicing faults for write access. In the normal case, do always want 1487 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1488 * that do not have writing enabled, when used by access_process_vm. 1489 */ 1490static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1491{ 1492 if (likely(vma->vm_flags & VM_WRITE)) 1493 pte = pte_mkwrite(pte); 1494 return pte; 1495} 1496 1497static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1498{ 1499 /* 1500 * If the source page was a PFN mapping, we don't have 1501 * a "struct page" for it. We do a best-effort copy by 1502 * just copying from the original user address. If that 1503 * fails, we just zero-fill it. Live with it. 1504 */ 1505 if (unlikely(!src)) { 1506 void *kaddr = kmap_atomic(dst, KM_USER0); 1507 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1508 1509 /* 1510 * This really shouldn't fail, because the page is there 1511 * in the page tables. But it might just be unreadable, 1512 * in which case we just give up and fill the result with 1513 * zeroes. 1514 */ 1515 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1516 memset(kaddr, 0, PAGE_SIZE); 1517 kunmap_atomic(kaddr, KM_USER0); 1518 flush_dcache_page(dst); 1519 return; 1520 1521 } 1522 copy_user_highpage(dst, src, va, vma); 1523} 1524 1525/* 1526 * This routine handles present pages, when users try to write 1527 * to a shared page. It is done by copying the page to a new address 1528 * and decrementing the shared-page counter for the old page. 1529 * 1530 * Note that this routine assumes that the protection checks have been 1531 * done by the caller (the low-level page fault routine in most cases). 1532 * Thus we can safely just mark it writable once we've done any necessary 1533 * COW. 1534 * 1535 * We also mark the page dirty at this point even though the page will 1536 * change only once the write actually happens. This avoids a few races, 1537 * and potentially makes it more efficient. 1538 * 1539 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1540 * but allow concurrent faults), with pte both mapped and locked. 1541 * We return with mmap_sem still held, but pte unmapped and unlocked. 1542 */ 1543static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1544 unsigned long address, pte_t *page_table, pmd_t *pmd, 1545 spinlock_t *ptl, pte_t orig_pte) 1546{ 1547 struct page *old_page, *new_page; 1548 pte_t entry; 1549 int reuse = 0, ret = 0; 1550 int page_mkwrite = 0; 1551 struct page *dirty_page = NULL; 1552 1553 old_page = vm_normal_page(vma, address, orig_pte); 1554 if (!old_page) 1555 goto gotten; 1556 1557 /* 1558 * Take out anonymous pages first, anonymous shared vmas are 1559 * not dirty accountable. 1560 */ 1561 if (PageAnon(old_page)) { 1562 if (!TestSetPageLocked(old_page)) { 1563 reuse = can_share_swap_page(old_page); 1564 unlock_page(old_page); 1565 } 1566 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 1567 (VM_WRITE|VM_SHARED))) { 1568 /* 1569 * Only catch write-faults on shared writable pages, 1570 * read-only shared pages can get COWed by 1571 * get_user_pages(.write=1, .force=1). 1572 */ 1573 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 1574 /* 1575 * Notify the address space that the page is about to 1576 * become writable so that it can prohibit this or wait 1577 * for the page to get into an appropriate state. 1578 * 1579 * We do this without the lock held, so that it can 1580 * sleep if it needs to. 1581 */ 1582 page_cache_get(old_page); 1583 pte_unmap_unlock(page_table, ptl); 1584 1585 if (vma->vm_ops->page_mkwrite(vma, old_page) < 0) 1586 goto unwritable_page; 1587 1588 /* 1589 * Since we dropped the lock we need to revalidate 1590 * the PTE as someone else may have changed it. If 1591 * they did, we just return, as we can count on the 1592 * MMU to tell us if they didn't also make it writable. 1593 */ 1594 page_table = pte_offset_map_lock(mm, pmd, address, 1595 &ptl); 1596 page_cache_release(old_page); 1597 if (!pte_same(*page_table, orig_pte)) 1598 goto unlock; 1599 1600 page_mkwrite = 1; 1601 } 1602 dirty_page = old_page; 1603 get_page(dirty_page); 1604 reuse = 1; 1605 } 1606 1607 if (reuse) { 1608 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1609 entry = pte_mkyoung(orig_pte); 1610 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1611 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 1612 update_mmu_cache(vma, address, entry); 1613 ret |= VM_FAULT_WRITE; 1614 goto unlock; 1615 } 1616 1617 /* 1618 * Ok, we need to copy. Oh, well.. 1619 */ 1620 page_cache_get(old_page); 1621gotten: 1622 pte_unmap_unlock(page_table, ptl); 1623 1624 if (unlikely(anon_vma_prepare(vma))) 1625 goto oom; 1626 VM_BUG_ON(old_page == ZERO_PAGE(0)); 1627 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 1628 if (!new_page) 1629 goto oom; 1630 cow_user_page(new_page, old_page, address, vma); 1631 1632 /* 1633 * Re-check the pte - we dropped the lock 1634 */ 1635 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1636 if (likely(pte_same(*page_table, orig_pte))) { 1637 if (old_page) { 1638 page_remove_rmap(old_page, vma); 1639 if (!PageAnon(old_page)) { 1640 dec_mm_counter(mm, file_rss); 1641 inc_mm_counter(mm, anon_rss); 1642 } 1643 } else 1644 inc_mm_counter(mm, anon_rss); 1645 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1646 entry = mk_pte(new_page, vma->vm_page_prot); 1647 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1648 /* 1649 * Clear the pte entry and flush it first, before updating the 1650 * pte with the new entry. This will avoid a race condition 1651 * seen in the presence of one thread doing SMC and another 1652 * thread doing COW. 1653 */ 1654 ptep_clear_flush(vma, address, page_table); 1655 set_pte_at(mm, address, page_table, entry); 1656 update_mmu_cache(vma, address, entry); 1657 lru_cache_add_active(new_page); 1658 page_add_new_anon_rmap(new_page, vma, address); 1659 1660 /* Free the old page.. */ 1661 new_page = old_page; 1662 ret |= VM_FAULT_WRITE; 1663 } 1664 if (new_page) 1665 page_cache_release(new_page); 1666 if (old_page) 1667 page_cache_release(old_page); 1668unlock: 1669 pte_unmap_unlock(page_table, ptl); 1670 if (dirty_page) { 1671 /* 1672 * Yes, Virginia, this is actually required to prevent a race 1673 * with clear_page_dirty_for_io() from clearing the page dirty 1674 * bit after it clear all dirty ptes, but before a racing 1675 * do_wp_page installs a dirty pte. 1676 * 1677 * do_no_page is protected similarly. 1678 */ 1679 wait_on_page_locked(dirty_page); 1680 set_page_dirty_balance(dirty_page, page_mkwrite); 1681 put_page(dirty_page); 1682 } 1683 return ret; 1684oom: 1685 if (old_page) 1686 page_cache_release(old_page); 1687 return VM_FAULT_OOM; 1688 1689unwritable_page: 1690 page_cache_release(old_page); 1691 return VM_FAULT_SIGBUS; 1692} 1693 1694/* 1695 * Helper functions for unmap_mapping_range(). 1696 * 1697 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 1698 * 1699 * We have to restart searching the prio_tree whenever we drop the lock, 1700 * since the iterator is only valid while the lock is held, and anyway 1701 * a later vma might be split and reinserted earlier while lock dropped. 1702 * 1703 * The list of nonlinear vmas could be handled more efficiently, using 1704 * a placeholder, but handle it in the same way until a need is shown. 1705 * It is important to search the prio_tree before nonlinear list: a vma 1706 * may become nonlinear and be shifted from prio_tree to nonlinear list 1707 * while the lock is dropped; but never shifted from list to prio_tree. 1708 * 1709 * In order to make forward progress despite restarting the search, 1710 * vm_truncate_count is used to mark a vma as now dealt with, so we can 1711 * quickly skip it next time around. Since the prio_tree search only 1712 * shows us those vmas affected by unmapping the range in question, we 1713 * can't efficiently keep all vmas in step with mapping->truncate_count: 1714 * so instead reset them all whenever it wraps back to 0 (then go to 1). 1715 * mapping->truncate_count and vma->vm_truncate_count are protected by 1716 * i_mmap_lock. 1717 * 1718 * In order to make forward progress despite repeatedly restarting some 1719 * large vma, note the restart_addr from unmap_vmas when it breaks out: 1720 * and restart from that address when we reach that vma again. It might 1721 * have been split or merged, shrunk or extended, but never shifted: so 1722 * restart_addr remains valid so long as it remains in the vma's range. 1723 * unmap_mapping_range forces truncate_count to leap over page-aligned 1724 * values so we can save vma's restart_addr in its truncate_count field. 1725 */ 1726#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 1727 1728static void reset_vma_truncate_counts(struct address_space *mapping) 1729{ 1730 struct vm_area_struct *vma; 1731 struct prio_tree_iter iter; 1732 1733 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 1734 vma->vm_truncate_count = 0; 1735 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 1736 vma->vm_truncate_count = 0; 1737} 1738 1739static int unmap_mapping_range_vma(struct vm_area_struct *vma, 1740 unsigned long start_addr, unsigned long end_addr, 1741 struct zap_details *details) 1742{ 1743 unsigned long restart_addr; 1744 int need_break; 1745 1746 /* 1747 * files that support invalidating or truncating portions of the 1748 * file from under mmaped areas must have their ->fault function 1749 * return a locked page (and set VM_FAULT_LOCKED in the return). 1750 * This provides synchronisation against concurrent unmapping here. 1751 */ 1752 1753again: 1754 restart_addr = vma->vm_truncate_count; 1755 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 1756 start_addr = restart_addr; 1757 if (start_addr >= end_addr) { 1758 /* Top of vma has been split off since last time */ 1759 vma->vm_truncate_count = details->truncate_count; 1760 return 0; 1761 } 1762 } 1763 1764 restart_addr = zap_page_range(vma, start_addr, 1765 end_addr - start_addr, details); 1766 need_break = need_resched() || 1767 need_lockbreak(details->i_mmap_lock); 1768 1769 if (restart_addr >= end_addr) { 1770 /* We have now completed this vma: mark it so */ 1771 vma->vm_truncate_count = details->truncate_count; 1772 if (!need_break) 1773 return 0; 1774 } else { 1775 /* Note restart_addr in vma's truncate_count field */ 1776 vma->vm_truncate_count = restart_addr; 1777 if (!need_break) 1778 goto again; 1779 } 1780 1781 spin_unlock(details->i_mmap_lock); 1782 cond_resched(); 1783 spin_lock(details->i_mmap_lock); 1784 return -EINTR; 1785} 1786 1787static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 1788 struct zap_details *details) 1789{ 1790 struct vm_area_struct *vma; 1791 struct prio_tree_iter iter; 1792 pgoff_t vba, vea, zba, zea; 1793 1794restart: 1795 vma_prio_tree_foreach(vma, &iter, root, 1796 details->first_index, details->last_index) { 1797 /* Skip quickly over those we have already dealt with */ 1798 if (vma->vm_truncate_count == details->truncate_count) 1799 continue; 1800 1801 vba = vma->vm_pgoff; 1802 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 1803 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 1804 zba = details->first_index; 1805 if (zba < vba) 1806 zba = vba; 1807 zea = details->last_index; 1808 if (zea > vea) 1809 zea = vea; 1810 1811 if (unmap_mapping_range_vma(vma, 1812 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 1813 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 1814 details) < 0) 1815 goto restart; 1816 } 1817} 1818 1819static inline void unmap_mapping_range_list(struct list_head *head, 1820 struct zap_details *details) 1821{ 1822 struct vm_area_struct *vma; 1823 1824 /* 1825 * In nonlinear VMAs there is no correspondence between virtual address 1826 * offset and file offset. So we must perform an exhaustive search 1827 * across *all* the pages in each nonlinear VMA, not just the pages 1828 * whose virtual address lies outside the file truncation point. 1829 */ 1830restart: 1831 list_for_each_entry(vma, head, shared.vm_set.list) { 1832 /* Skip quickly over those we have already dealt with */ 1833 if (vma->vm_truncate_count == details->truncate_count) 1834 continue; 1835 details->nonlinear_vma = vma; 1836 if (unmap_mapping_range_vma(vma, vma->vm_start, 1837 vma->vm_end, details) < 0) 1838 goto restart; 1839 } 1840} 1841 1842/** 1843 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 1844 * @mapping: the address space containing mmaps to be unmapped. 1845 * @holebegin: byte in first page to unmap, relative to the start of 1846 * the underlying file. This will be rounded down to a PAGE_SIZE 1847 * boundary. Note that this is different from vmtruncate(), which 1848 * must keep the partial page. In contrast, we must get rid of 1849 * partial pages. 1850 * @holelen: size of prospective hole in bytes. This will be rounded 1851 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 1852 * end of the file. 1853 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 1854 * but 0 when invalidating pagecache, don't throw away private data. 1855 */ 1856void unmap_mapping_range(struct address_space *mapping, 1857 loff_t const holebegin, loff_t const holelen, int even_cows) 1858{ 1859 struct zap_details details; 1860 pgoff_t hba = holebegin >> PAGE_SHIFT; 1861 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1862 1863 /* Check for overflow. */ 1864 if (sizeof(holelen) > sizeof(hlen)) { 1865 long long holeend = 1866 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1867 if (holeend & ~(long long)ULONG_MAX) 1868 hlen = ULONG_MAX - hba + 1; 1869 } 1870 1871 details.check_mapping = even_cows? NULL: mapping; 1872 details.nonlinear_vma = NULL; 1873 details.first_index = hba; 1874 details.last_index = hba + hlen - 1; 1875 if (details.last_index < details.first_index) 1876 details.last_index = ULONG_MAX; 1877 details.i_mmap_lock = &mapping->i_mmap_lock; 1878 1879 spin_lock(&mapping->i_mmap_lock); 1880 1881 /* Protect against endless unmapping loops */ 1882 mapping->truncate_count++; 1883 if (unlikely(is_restart_addr(mapping->truncate_count))) { 1884 if (mapping->truncate_count == 0) 1885 reset_vma_truncate_counts(mapping); 1886 mapping->truncate_count++; 1887 } 1888 details.truncate_count = mapping->truncate_count; 1889 1890 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 1891 unmap_mapping_range_tree(&mapping->i_mmap, &details); 1892 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 1893 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 1894 spin_unlock(&mapping->i_mmap_lock); 1895} 1896EXPORT_SYMBOL(unmap_mapping_range); 1897 1898/** 1899 * vmtruncate - unmap mappings "freed" by truncate() syscall 1900 * @inode: inode of the file used 1901 * @offset: file offset to start truncating 1902 * 1903 * NOTE! We have to be ready to update the memory sharing 1904 * between the file and the memory map for a potential last 1905 * incomplete page. Ugly, but necessary. 1906 */ 1907int vmtruncate(struct inode * inode, loff_t offset) 1908{ 1909 struct address_space *mapping = inode->i_mapping; 1910 unsigned long limit; 1911 1912 if (inode->i_size < offset) 1913 goto do_expand; 1914 /* 1915 * truncation of in-use swapfiles is disallowed - it would cause 1916 * subsequent swapout to scribble on the now-freed blocks. 1917 */ 1918 if (IS_SWAPFILE(inode)) 1919 goto out_busy; 1920 i_size_write(inode, offset); 1921 1922 /* 1923 * unmap_mapping_range is called twice, first simply for efficiency 1924 * so that truncate_inode_pages does fewer single-page unmaps. However 1925 * after this first call, and before truncate_inode_pages finishes, 1926 * it is possible for private pages to be COWed, which remain after 1927 * truncate_inode_pages finishes, hence the second unmap_mapping_range 1928 * call must be made for correctness. 1929 */ 1930 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1931 truncate_inode_pages(mapping, offset); 1932 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1933 goto out_truncate; 1934 1935do_expand: 1936 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1937 if (limit != RLIM_INFINITY && offset > limit) 1938 goto out_sig; 1939 if (offset > inode->i_sb->s_maxbytes) 1940 goto out_big; 1941 i_size_write(inode, offset); 1942 1943out_truncate: 1944 if (inode->i_op && inode->i_op->truncate) 1945 inode->i_op->truncate(inode); 1946 return 0; 1947out_sig: 1948 send_sig(SIGXFSZ, current, 0); 1949out_big: 1950 return -EFBIG; 1951out_busy: 1952 return -ETXTBSY; 1953} 1954EXPORT_SYMBOL(vmtruncate); 1955 1956int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 1957{ 1958 struct address_space *mapping = inode->i_mapping; 1959 1960 /* 1961 * If the underlying filesystem is not going to provide 1962 * a way to truncate a range of blocks (punch a hole) - 1963 * we should return failure right now. 1964 */ 1965 if (!inode->i_op || !inode->i_op->truncate_range) 1966 return -ENOSYS; 1967 1968 mutex_lock(&inode->i_mutex); 1969 down_write(&inode->i_alloc_sem); 1970 unmap_mapping_range(mapping, offset, (end - offset), 1); 1971 truncate_inode_pages_range(mapping, offset, end); 1972 unmap_mapping_range(mapping, offset, (end - offset), 1); 1973 inode->i_op->truncate_range(inode, offset, end); 1974 up_write(&inode->i_alloc_sem); 1975 mutex_unlock(&inode->i_mutex); 1976 1977 return 0; 1978} 1979 1980/** 1981 * swapin_readahead - swap in pages in hope we need them soon 1982 * @entry: swap entry of this memory 1983 * @addr: address to start 1984 * @vma: user vma this addresses belong to 1985 * 1986 * Primitive swap readahead code. We simply read an aligned block of 1987 * (1 << page_cluster) entries in the swap area. This method is chosen 1988 * because it doesn't cost us any seek time. We also make sure to queue 1989 * the 'original' request together with the readahead ones... 1990 * 1991 * This has been extended to use the NUMA policies from the mm triggering 1992 * the readahead. 1993 * 1994 * Caller must hold down_read on the vma->vm_mm if vma is not NULL. 1995 */ 1996void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) 1997{ 1998#ifdef CONFIG_NUMA 1999 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; 2000#endif 2001 int i, num; 2002 struct page *new_page; 2003 unsigned long offset; 2004 2005 /* 2006 * Get the number of handles we should do readahead io to. 2007 */ 2008 num = valid_swaphandles(entry, &offset); 2009 for (i = 0; i < num; offset++, i++) { 2010 /* Ok, do the async read-ahead now */ 2011 new_page = read_swap_cache_async(swp_entry(swp_type(entry), 2012 offset), vma, addr); 2013 if (!new_page) 2014 break; 2015 page_cache_release(new_page); 2016#ifdef CONFIG_NUMA 2017 /* 2018 * Find the next applicable VMA for the NUMA policy. 2019 */ 2020 addr += PAGE_SIZE; 2021 if (addr == 0) 2022 vma = NULL; 2023 if (vma) { 2024 if (addr >= vma->vm_end) { 2025 vma = next_vma; 2026 next_vma = vma ? vma->vm_next : NULL; 2027 } 2028 if (vma && addr < vma->vm_start) 2029 vma = NULL; 2030 } else { 2031 if (next_vma && addr >= next_vma->vm_start) { 2032 vma = next_vma; 2033 next_vma = vma->vm_next; 2034 } 2035 } 2036#endif 2037 } 2038 lru_add_drain(); /* Push any new pages onto the LRU now */ 2039} 2040 2041/* 2042 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2043 * but allow concurrent faults), and pte mapped but not yet locked. 2044 * We return with mmap_sem still held, but pte unmapped and unlocked. 2045 */ 2046static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2047 unsigned long address, pte_t *page_table, pmd_t *pmd, 2048 int write_access, pte_t orig_pte) 2049{ 2050 spinlock_t *ptl; 2051 struct page *page; 2052 swp_entry_t entry; 2053 pte_t pte; 2054 int ret = 0; 2055 2056 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2057 goto out; 2058 2059 entry = pte_to_swp_entry(orig_pte); 2060 if (is_migration_entry(entry)) { 2061 migration_entry_wait(mm, pmd, address); 2062 goto out; 2063 } 2064 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2065 page = lookup_swap_cache(entry); 2066 if (!page) { 2067 grab_swap_token(); /* Contend for token _before_ read-in */ 2068 swapin_readahead(entry, address, vma); 2069 page = read_swap_cache_async(entry, vma, address); 2070 if (!page) { 2071 /* 2072 * Back out if somebody else faulted in this pte 2073 * while we released the pte lock. 2074 */ 2075 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2076 if (likely(pte_same(*page_table, orig_pte))) 2077 ret = VM_FAULT_OOM; 2078 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2079 goto unlock; 2080 } 2081 2082 /* Had to read the page from swap area: Major fault */ 2083 ret = VM_FAULT_MAJOR; 2084 count_vm_event(PGMAJFAULT); 2085 } 2086 2087 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2088 mark_page_accessed(page); 2089 lock_page(page); 2090 2091 /* 2092 * Back out if somebody else already faulted in this pte. 2093 */ 2094 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2095 if (unlikely(!pte_same(*page_table, orig_pte))) 2096 goto out_nomap; 2097 2098 if (unlikely(!PageUptodate(page))) { 2099 ret = VM_FAULT_SIGBUS; 2100 goto out_nomap; 2101 } 2102 2103 /* The page isn't present yet, go ahead with the fault. */ 2104 2105 inc_mm_counter(mm, anon_rss); 2106 pte = mk_pte(page, vma->vm_page_prot); 2107 if (write_access && can_share_swap_page(page)) { 2108 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2109 write_access = 0; 2110 } 2111 2112 flush_icache_page(vma, page); 2113 set_pte_at(mm, address, page_table, pte); 2114 page_add_anon_rmap(page, vma, address); 2115 2116 swap_free(entry); 2117 if (vm_swap_full()) 2118 remove_exclusive_swap_page(page); 2119 unlock_page(page); 2120 2121 if (write_access) { 2122 /* XXX: We could OR the do_wp_page code with this one? */ 2123 if (do_wp_page(mm, vma, address, 2124 page_table, pmd, ptl, pte) & VM_FAULT_OOM) 2125 ret = VM_FAULT_OOM; 2126 goto out; 2127 } 2128 2129 /* No need to invalidate - it was non-present before */ 2130 update_mmu_cache(vma, address, pte); 2131unlock: 2132 pte_unmap_unlock(page_table, ptl); 2133out: 2134 return ret; 2135out_nomap: 2136 pte_unmap_unlock(page_table, ptl); 2137 unlock_page(page); 2138 page_cache_release(page); 2139 return ret; 2140} 2141 2142/* 2143 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2144 * but allow concurrent faults), and pte mapped but not yet locked. 2145 * We return with mmap_sem still held, but pte unmapped and unlocked. 2146 */ 2147static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2148 unsigned long address, pte_t *page_table, pmd_t *pmd, 2149 int write_access) 2150{ 2151 struct page *page; 2152 spinlock_t *ptl; 2153 pte_t entry; 2154 2155 /* Allocate our own private page. */ 2156 pte_unmap(page_table); 2157 2158 if (unlikely(anon_vma_prepare(vma))) 2159 goto oom; 2160 page = alloc_zeroed_user_highpage_movable(vma, address); 2161 if (!page) 2162 goto oom; 2163 2164 entry = mk_pte(page, vma->vm_page_prot); 2165 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2166 2167 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2168 if (!pte_none(*page_table)) 2169 goto release; 2170 inc_mm_counter(mm, anon_rss); 2171 lru_cache_add_active(page); 2172 page_add_new_anon_rmap(page, vma, address); 2173 set_pte_at(mm, address, page_table, entry); 2174 2175 /* No need to invalidate - it was non-present before */ 2176 update_mmu_cache(vma, address, entry); 2177unlock: 2178 pte_unmap_unlock(page_table, ptl); 2179 return 0; 2180release: 2181 page_cache_release(page); 2182 goto unlock; 2183oom: 2184 return VM_FAULT_OOM; 2185} 2186 2187/* 2188 * __do_fault() tries to create a new page mapping. It aggressively 2189 * tries to share with existing pages, but makes a separate copy if 2190 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 2191 * the next page fault. 2192 * 2193 * As this is called only for pages that do not currently exist, we 2194 * do not need to flush old virtual caches or the TLB. 2195 * 2196 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2197 * but allow concurrent faults), and pte neither mapped nor locked. 2198 * We return with mmap_sem still held, but pte unmapped and unlocked. 2199 */ 2200static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2201 unsigned long address, pmd_t *pmd, 2202 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2203{ 2204 pte_t *page_table; 2205 spinlock_t *ptl; 2206 struct page *page; 2207 pte_t entry; 2208 int anon = 0; 2209 struct page *dirty_page = NULL; 2210 struct vm_fault vmf; 2211 int ret; 2212 int page_mkwrite = 0; 2213 2214 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2215 vmf.pgoff = pgoff; 2216 vmf.flags = flags; 2217 vmf.page = NULL; 2218 2219 BUG_ON(vma->vm_flags & VM_PFNMAP); 2220 2221 if (likely(vma->vm_ops->fault)) { 2222 ret = vma->vm_ops->fault(vma, &vmf); 2223 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2224 return ret; 2225 } else { 2226 /* Legacy ->nopage path */ 2227 ret = 0; 2228 vmf.page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); 2229 /* no page was available -- either SIGBUS or OOM */ 2230 if (unlikely(vmf.page == NOPAGE_SIGBUS)) 2231 return VM_FAULT_SIGBUS; 2232 else if (unlikely(vmf.page == NOPAGE_OOM)) 2233 return VM_FAULT_OOM; 2234 } 2235 2236 /* 2237 * For consistency in subsequent calls, make the faulted page always 2238 * locked. 2239 */ 2240 if (unlikely(!(ret & VM_FAULT_LOCKED))) 2241 lock_page(vmf.page); 2242 else 2243 VM_BUG_ON(!PageLocked(vmf.page)); 2244 2245 /* 2246 * Should we do an early C-O-W break? 2247 */ 2248 page = vmf.page; 2249 if (flags & FAULT_FLAG_WRITE) { 2250 if (!(vma->vm_flags & VM_SHARED)) { 2251 anon = 1; 2252 if (unlikely(anon_vma_prepare(vma))) { 2253 ret = VM_FAULT_OOM; 2254 goto out; 2255 } 2256 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, 2257 vma, address); 2258 if (!page) { 2259 ret = VM_FAULT_OOM; 2260 goto out; 2261 } 2262 copy_user_highpage(page, vmf.page, address, vma); 2263 } else { 2264 /* 2265 * If the page will be shareable, see if the backing 2266 * address space wants to know that the page is about 2267 * to become writable 2268 */ 2269 if (vma->vm_ops->page_mkwrite) { 2270 unlock_page(page); 2271 if (vma->vm_ops->page_mkwrite(vma, page) < 0) { 2272 ret = VM_FAULT_SIGBUS; 2273 anon = 1; /* no anon but release vmf.page */ 2274 goto out_unlocked; 2275 } 2276 lock_page(page); 2277 /* 2278 * XXX: this is not quite right (racy vs 2279 * invalidate) to unlock and relock the page 2280 * like this, however a better fix requires 2281 * reworking page_mkwrite locking API, which 2282 * is better done later. 2283 */ 2284 if (!page->mapping) { 2285 ret = 0; 2286 anon = 1; /* no anon but release vmf.page */ 2287 goto out; 2288 } 2289 page_mkwrite = 1; 2290 } 2291 } 2292 2293 } 2294 2295 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2296 2297 /* 2298 * This silly early PAGE_DIRTY setting removes a race 2299 * due to the bad i386 page protection. But it's valid 2300 * for other architectures too. 2301 * 2302 * Note that if write_access is true, we either now have 2303 * an exclusive copy of the page, or this is a shared mapping, 2304 * so we can make it writable and dirty to avoid having to 2305 * handle that later. 2306 */ 2307 /* Only go through if we didn't race with anybody else... */ 2308 if (likely(pte_same(*page_table, orig_pte))) { 2309 flush_icache_page(vma, page); 2310 entry = mk_pte(page, vma->vm_page_prot); 2311 if (flags & FAULT_FLAG_WRITE) 2312 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2313 set_pte_at(mm, address, page_table, entry); 2314 if (anon) { 2315 inc_mm_counter(mm, anon_rss); 2316 lru_cache_add_active(page); 2317 page_add_new_anon_rmap(page, vma, address); 2318 } else { 2319 inc_mm_counter(mm, file_rss); 2320 page_add_file_rmap(page); 2321 if (flags & FAULT_FLAG_WRITE) { 2322 dirty_page = page; 2323 get_page(dirty_page); 2324 } 2325 } 2326 2327 /* no need to invalidate: a not-present page won't be cached */ 2328 update_mmu_cache(vma, address, entry); 2329 } else { 2330 if (anon) 2331 page_cache_release(page); 2332 else 2333 anon = 1; /* no anon but release faulted_page */ 2334 } 2335 2336 pte_unmap_unlock(page_table, ptl); 2337 2338out: 2339 unlock_page(vmf.page); 2340out_unlocked: 2341 if (anon) 2342 page_cache_release(vmf.page); 2343 else if (dirty_page) { 2344 set_page_dirty_balance(dirty_page, page_mkwrite); 2345 put_page(dirty_page); 2346 } 2347 2348 return ret; 2349} 2350 2351static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2352 unsigned long address, pte_t *page_table, pmd_t *pmd, 2353 int write_access, pte_t orig_pte) 2354{ 2355 pgoff_t pgoff = (((address & PAGE_MASK) 2356 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 2357 unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0); 2358 2359 pte_unmap(page_table); 2360 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2361} 2362 2363 2364/* 2365 * do_no_pfn() tries to create a new page mapping for a page without 2366 * a struct_page backing it 2367 * 2368 * As this is called only for pages that do not currently exist, we 2369 * do not need to flush old virtual caches or the TLB. 2370 * 2371 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2372 * but allow concurrent faults), and pte mapped but not yet locked. 2373 * We return with mmap_sem still held, but pte unmapped and unlocked. 2374 * 2375 * It is expected that the ->nopfn handler always returns the same pfn 2376 * for a given virtual mapping. 2377 * 2378 * Mark this `noinline' to prevent it from bloating the main pagefault code. 2379 */ 2380static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma, 2381 unsigned long address, pte_t *page_table, pmd_t *pmd, 2382 int write_access) 2383{ 2384 spinlock_t *ptl; 2385 pte_t entry; 2386 unsigned long pfn; 2387 2388 pte_unmap(page_table); 2389 BUG_ON(!(vma->vm_flags & VM_PFNMAP)); 2390 BUG_ON(is_cow_mapping(vma->vm_flags)); 2391 2392 pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK); 2393 if (unlikely(pfn == NOPFN_OOM)) 2394 return VM_FAULT_OOM; 2395 else if (unlikely(pfn == NOPFN_SIGBUS)) 2396 return VM_FAULT_SIGBUS; 2397 else if (unlikely(pfn == NOPFN_REFAULT)) 2398 return 0; 2399 2400 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2401 2402 /* Only go through if we didn't race with anybody else... */ 2403 if (pte_none(*page_table)) { 2404 entry = pfn_pte(pfn, vma->vm_page_prot); 2405 if (write_access) 2406 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2407 set_pte_at(mm, address, page_table, entry); 2408 } 2409 pte_unmap_unlock(page_table, ptl); 2410 return 0; 2411} 2412 2413/* 2414 * Fault of a previously existing named mapping. Repopulate the pte 2415 * from the encoded file_pte if possible. This enables swappable 2416 * nonlinear vmas. 2417 * 2418 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2419 * but allow concurrent faults), and pte mapped but not yet locked. 2420 * We return with mmap_sem still held, but pte unmapped and unlocked. 2421 */ 2422static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2423 unsigned long address, pte_t *page_table, pmd_t *pmd, 2424 int write_access, pte_t orig_pte) 2425{ 2426 unsigned int flags = FAULT_FLAG_NONLINEAR | 2427 (write_access ? FAULT_FLAG_WRITE : 0); 2428 pgoff_t pgoff; 2429 2430 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2431 return 0; 2432 2433 if (unlikely(!(vma->vm_flags & VM_NONLINEAR) || 2434 !(vma->vm_flags & VM_CAN_NONLINEAR))) { 2435 /* 2436 * Page table corrupted: show pte and kill process. 2437 */ 2438 print_bad_pte(vma, orig_pte, address); 2439 return VM_FAULT_OOM; 2440 } 2441 2442 pgoff = pte_to_pgoff(orig_pte); 2443 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2444} 2445 2446/* 2447 * These routines also need to handle stuff like marking pages dirty 2448 * and/or accessed for architectures that don't do it in hardware (most 2449 * RISC architectures). The early dirtying is also good on the i386. 2450 * 2451 * There is also a hook called "update_mmu_cache()" that architectures 2452 * with external mmu caches can use to update those (ie the Sparc or 2453 * PowerPC hashed page tables that act as extended TLBs). 2454 * 2455 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2456 * but allow concurrent faults), and pte mapped but not yet locked. 2457 * We return with mmap_sem still held, but pte unmapped and unlocked. 2458 */ 2459static inline int handle_pte_fault(struct mm_struct *mm, 2460 struct vm_area_struct *vma, unsigned long address, 2461 pte_t *pte, pmd_t *pmd, int write_access) 2462{ 2463 pte_t entry; 2464 spinlock_t *ptl; 2465 2466 entry = *pte; 2467 if (!pte_present(entry)) { 2468 if (pte_none(entry)) { 2469 if (vma->vm_ops) { 2470 if (vma->vm_ops->fault || vma->vm_ops->nopage) 2471 return do_linear_fault(mm, vma, address, 2472 pte, pmd, write_access, entry); 2473 if (unlikely(vma->vm_ops->nopfn)) 2474 return do_no_pfn(mm, vma, address, pte, 2475 pmd, write_access); 2476 } 2477 return do_anonymous_page(mm, vma, address, 2478 pte, pmd, write_access); 2479 } 2480 if (pte_file(entry)) 2481 return do_nonlinear_fault(mm, vma, address, 2482 pte, pmd, write_access, entry); 2483 return do_swap_page(mm, vma, address, 2484 pte, pmd, write_access, entry); 2485 } 2486 2487 ptl = pte_lockptr(mm, pmd); 2488 spin_lock(ptl); 2489 if (unlikely(!pte_same(*pte, entry))) 2490 goto unlock; 2491 if (write_access) { 2492 if (!pte_write(entry)) 2493 return do_wp_page(mm, vma, address, 2494 pte, pmd, ptl, entry); 2495 entry = pte_mkdirty(entry); 2496 } 2497 entry = pte_mkyoung(entry); 2498 if (ptep_set_access_flags(vma, address, pte, entry, write_access)) { 2499 update_mmu_cache(vma, address, entry); 2500 } else { 2501 /* 2502 * This is needed only for protection faults but the arch code 2503 * is not yet telling us if this is a protection fault or not. 2504 * This still avoids useless tlb flushes for .text page faults 2505 * with threads. 2506 */ 2507 if (write_access) 2508 flush_tlb_page(vma, address); 2509 } 2510unlock: 2511 pte_unmap_unlock(pte, ptl); 2512 return 0; 2513} 2514 2515/* 2516 * By the time we get here, we already hold the mm semaphore 2517 */ 2518int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2519 unsigned long address, int write_access) 2520{ 2521 pgd_t *pgd; 2522 pud_t *pud; 2523 pmd_t *pmd; 2524 pte_t *pte; 2525 2526 __set_current_state(TASK_RUNNING); 2527 2528 count_vm_event(PGFAULT); 2529 2530 if (unlikely(is_vm_hugetlb_page(vma))) 2531 return hugetlb_fault(mm, vma, address, write_access); 2532 2533 pgd = pgd_offset(mm, address); 2534 pud = pud_alloc(mm, pgd, address); 2535 if (!pud) 2536 return VM_FAULT_OOM; 2537 pmd = pmd_alloc(mm, pud, address); 2538 if (!pmd) 2539 return VM_FAULT_OOM; 2540 pte = pte_alloc_map(mm, pmd, address); 2541 if (!pte) 2542 return VM_FAULT_OOM; 2543 2544 return handle_pte_fault(mm, vma, address, pte, pmd, write_access); 2545} 2546 2547#ifndef __PAGETABLE_PUD_FOLDED 2548/* 2549 * Allocate page upper directory. 2550 * We've already handled the fast-path in-line. 2551 */ 2552int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2553{ 2554 pud_t *new = pud_alloc_one(mm, address); 2555 if (!new) 2556 return -ENOMEM; 2557 2558 spin_lock(&mm->page_table_lock); 2559 if (pgd_present(*pgd)) /* Another has populated it */ 2560 pud_free(new); 2561 else 2562 pgd_populate(mm, pgd, new); 2563 spin_unlock(&mm->page_table_lock); 2564 return 0; 2565} 2566#endif /* __PAGETABLE_PUD_FOLDED */ 2567 2568#ifndef __PAGETABLE_PMD_FOLDED 2569/* 2570 * Allocate page middle directory. 2571 * We've already handled the fast-path in-line. 2572 */ 2573int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2574{ 2575 pmd_t *new = pmd_alloc_one(mm, address); 2576 if (!new) 2577 return -ENOMEM; 2578 2579 spin_lock(&mm->page_table_lock); 2580#ifndef __ARCH_HAS_4LEVEL_HACK 2581 if (pud_present(*pud)) /* Another has populated it */ 2582 pmd_free(new); 2583 else 2584 pud_populate(mm, pud, new); 2585#else 2586 if (pgd_present(*pud)) /* Another has populated it */ 2587 pmd_free(new); 2588 else 2589 pgd_populate(mm, pud, new); 2590#endif /* __ARCH_HAS_4LEVEL_HACK */ 2591 spin_unlock(&mm->page_table_lock); 2592 return 0; 2593} 2594#endif /* __PAGETABLE_PMD_FOLDED */ 2595 2596int make_pages_present(unsigned long addr, unsigned long end) 2597{ 2598 int ret, len, write; 2599 struct vm_area_struct * vma; 2600 2601 vma = find_vma(current->mm, addr); 2602 if (!vma) 2603 return -1; 2604 write = (vma->vm_flags & VM_WRITE) != 0; 2605 BUG_ON(addr >= end); 2606 BUG_ON(end > vma->vm_end); 2607 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; 2608 ret = get_user_pages(current, current->mm, addr, 2609 len, write, 0, NULL, NULL); 2610 if (ret < 0) 2611 return ret; 2612 return ret == len ? 0 : -1; 2613} 2614 2615/* 2616 * Map a vmalloc()-space virtual address to the physical page. 2617 */ 2618struct page * vmalloc_to_page(void * vmalloc_addr) 2619{ 2620 unsigned long addr = (unsigned long) vmalloc_addr; 2621 struct page *page = NULL; 2622 pgd_t *pgd = pgd_offset_k(addr); 2623 pud_t *pud; 2624 pmd_t *pmd; 2625 pte_t *ptep, pte; 2626 2627 if (!pgd_none(*pgd)) { 2628 pud = pud_offset(pgd, addr); 2629 if (!pud_none(*pud)) { 2630 pmd = pmd_offset(pud, addr); 2631 if (!pmd_none(*pmd)) { 2632 ptep = pte_offset_map(pmd, addr); 2633 pte = *ptep; 2634 if (pte_present(pte)) 2635 page = pte_page(pte); 2636 pte_unmap(ptep); 2637 } 2638 } 2639 } 2640 return page; 2641} 2642 2643EXPORT_SYMBOL(vmalloc_to_page); 2644 2645/* 2646 * Map a vmalloc()-space virtual address to the physical page frame number. 2647 */ 2648unsigned long vmalloc_to_pfn(void * vmalloc_addr) 2649{ 2650 return page_to_pfn(vmalloc_to_page(vmalloc_addr)); 2651} 2652 2653EXPORT_SYMBOL(vmalloc_to_pfn); 2654 2655#if !defined(__HAVE_ARCH_GATE_AREA) 2656 2657#if defined(AT_SYSINFO_EHDR) 2658static struct vm_area_struct gate_vma; 2659 2660static int __init gate_vma_init(void) 2661{ 2662 gate_vma.vm_mm = NULL; 2663 gate_vma.vm_start = FIXADDR_USER_START; 2664 gate_vma.vm_end = FIXADDR_USER_END; 2665 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 2666 gate_vma.vm_page_prot = __P101; 2667 /* 2668 * Make sure the vDSO gets into every core dump. 2669 * Dumping its contents makes post-mortem fully interpretable later 2670 * without matching up the same kernel and hardware config to see 2671 * what PC values meant. 2672 */ 2673 gate_vma.vm_flags |= VM_ALWAYSDUMP; 2674 return 0; 2675} 2676__initcall(gate_vma_init); 2677#endif 2678 2679struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 2680{ 2681#ifdef AT_SYSINFO_EHDR 2682 return &gate_vma; 2683#else 2684 return NULL; 2685#endif 2686} 2687 2688int in_gate_area_no_task(unsigned long addr) 2689{ 2690#ifdef AT_SYSINFO_EHDR 2691 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 2692 return 1; 2693#endif 2694 return 0; 2695} 2696 2697#endif /* __HAVE_ARCH_GATE_AREA */ 2698 2699/* 2700 * Access another process' address space. 2701 * Source/target buffer must be kernel space, 2702 * Do not walk the page table directly, use get_user_pages 2703 */ 2704int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2705{ 2706 struct mm_struct *mm; 2707 struct vm_area_struct *vma; 2708 struct page *page; 2709 void *old_buf = buf; 2710 2711 mm = get_task_mm(tsk); 2712 if (!mm) 2713 return 0; 2714 2715 down_read(&mm->mmap_sem); 2716 /* ignore errors, just check how much was successfully transferred */ 2717 while (len) { 2718 int bytes, ret, offset; 2719 void *maddr; 2720 2721 ret = get_user_pages(tsk, mm, addr, 1, 2722 write, 1, &page, &vma); 2723 if (ret <= 0) 2724 break; 2725 2726 bytes = len; 2727 offset = addr & (PAGE_SIZE-1); 2728 if (bytes > PAGE_SIZE-offset) 2729 bytes = PAGE_SIZE-offset; 2730 2731 maddr = kmap(page); 2732 if (write) { 2733 copy_to_user_page(vma, page, addr, 2734 maddr + offset, buf, bytes); 2735 set_page_dirty_lock(page); 2736 } else { 2737 copy_from_user_page(vma, page, addr, 2738 buf, maddr + offset, bytes); 2739 } 2740 kunmap(page); 2741 page_cache_release(page); 2742 len -= bytes; 2743 buf += bytes; 2744 addr += bytes; 2745 } 2746 up_read(&mm->mmap_sem); 2747 mmput(mm); 2748 2749 return buf - old_buf; 2750} 2751