memory.c revision 4c21e2f2441dc5fbb957b030333f5a3f2d02dea7
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/init.h> 51 52#include <asm/pgalloc.h> 53#include <asm/uaccess.h> 54#include <asm/tlb.h> 55#include <asm/tlbflush.h> 56#include <asm/pgtable.h> 57 58#include <linux/swapops.h> 59#include <linux/elf.h> 60 61#ifndef CONFIG_NEED_MULTIPLE_NODES 62/* use the per-pgdat data instead for discontigmem - mbligh */ 63unsigned long max_mapnr; 64struct page *mem_map; 65 66EXPORT_SYMBOL(max_mapnr); 67EXPORT_SYMBOL(mem_map); 68#endif 69 70unsigned long num_physpages; 71/* 72 * A number of key systems in x86 including ioremap() rely on the assumption 73 * that high_memory defines the upper bound on direct map memory, then end 74 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 75 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 76 * and ZONE_HIGHMEM. 77 */ 78void * high_memory; 79unsigned long vmalloc_earlyreserve; 80 81EXPORT_SYMBOL(num_physpages); 82EXPORT_SYMBOL(high_memory); 83EXPORT_SYMBOL(vmalloc_earlyreserve); 84 85/* 86 * If a p?d_bad entry is found while walking page tables, report 87 * the error, before resetting entry to p?d_none. Usually (but 88 * very seldom) called out from the p?d_none_or_clear_bad macros. 89 */ 90 91void pgd_clear_bad(pgd_t *pgd) 92{ 93 pgd_ERROR(*pgd); 94 pgd_clear(pgd); 95} 96 97void pud_clear_bad(pud_t *pud) 98{ 99 pud_ERROR(*pud); 100 pud_clear(pud); 101} 102 103void pmd_clear_bad(pmd_t *pmd) 104{ 105 pmd_ERROR(*pmd); 106 pmd_clear(pmd); 107} 108 109/* 110 * Note: this doesn't free the actual pages themselves. That 111 * has been handled earlier when unmapping all the memory regions. 112 */ 113static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd) 114{ 115 struct page *page = pmd_page(*pmd); 116 pmd_clear(pmd); 117 pte_lock_deinit(page); 118 pte_free_tlb(tlb, page); 119 dec_page_state(nr_page_table_pages); 120 tlb->mm->nr_ptes--; 121} 122 123static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 124 unsigned long addr, unsigned long end, 125 unsigned long floor, unsigned long ceiling) 126{ 127 pmd_t *pmd; 128 unsigned long next; 129 unsigned long start; 130 131 start = addr; 132 pmd = pmd_offset(pud, addr); 133 do { 134 next = pmd_addr_end(addr, end); 135 if (pmd_none_or_clear_bad(pmd)) 136 continue; 137 free_pte_range(tlb, pmd); 138 } while (pmd++, addr = next, addr != end); 139 140 start &= PUD_MASK; 141 if (start < floor) 142 return; 143 if (ceiling) { 144 ceiling &= PUD_MASK; 145 if (!ceiling) 146 return; 147 } 148 if (end - 1 > ceiling - 1) 149 return; 150 151 pmd = pmd_offset(pud, start); 152 pud_clear(pud); 153 pmd_free_tlb(tlb, pmd); 154} 155 156static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 157 unsigned long addr, unsigned long end, 158 unsigned long floor, unsigned long ceiling) 159{ 160 pud_t *pud; 161 unsigned long next; 162 unsigned long start; 163 164 start = addr; 165 pud = pud_offset(pgd, addr); 166 do { 167 next = pud_addr_end(addr, end); 168 if (pud_none_or_clear_bad(pud)) 169 continue; 170 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 171 } while (pud++, addr = next, addr != end); 172 173 start &= PGDIR_MASK; 174 if (start < floor) 175 return; 176 if (ceiling) { 177 ceiling &= PGDIR_MASK; 178 if (!ceiling) 179 return; 180 } 181 if (end - 1 > ceiling - 1) 182 return; 183 184 pud = pud_offset(pgd, start); 185 pgd_clear(pgd); 186 pud_free_tlb(tlb, pud); 187} 188 189/* 190 * This function frees user-level page tables of a process. 191 * 192 * Must be called with pagetable lock held. 193 */ 194void free_pgd_range(struct mmu_gather **tlb, 195 unsigned long addr, unsigned long end, 196 unsigned long floor, unsigned long ceiling) 197{ 198 pgd_t *pgd; 199 unsigned long next; 200 unsigned long start; 201 202 /* 203 * The next few lines have given us lots of grief... 204 * 205 * Why are we testing PMD* at this top level? Because often 206 * there will be no work to do at all, and we'd prefer not to 207 * go all the way down to the bottom just to discover that. 208 * 209 * Why all these "- 1"s? Because 0 represents both the bottom 210 * of the address space and the top of it (using -1 for the 211 * top wouldn't help much: the masks would do the wrong thing). 212 * The rule is that addr 0 and floor 0 refer to the bottom of 213 * the address space, but end 0 and ceiling 0 refer to the top 214 * Comparisons need to use "end - 1" and "ceiling - 1" (though 215 * that end 0 case should be mythical). 216 * 217 * Wherever addr is brought up or ceiling brought down, we must 218 * be careful to reject "the opposite 0" before it confuses the 219 * subsequent tests. But what about where end is brought down 220 * by PMD_SIZE below? no, end can't go down to 0 there. 221 * 222 * Whereas we round start (addr) and ceiling down, by different 223 * masks at different levels, in order to test whether a table 224 * now has no other vmas using it, so can be freed, we don't 225 * bother to round floor or end up - the tests don't need that. 226 */ 227 228 addr &= PMD_MASK; 229 if (addr < floor) { 230 addr += PMD_SIZE; 231 if (!addr) 232 return; 233 } 234 if (ceiling) { 235 ceiling &= PMD_MASK; 236 if (!ceiling) 237 return; 238 } 239 if (end - 1 > ceiling - 1) 240 end -= PMD_SIZE; 241 if (addr > end - 1) 242 return; 243 244 start = addr; 245 pgd = pgd_offset((*tlb)->mm, addr); 246 do { 247 next = pgd_addr_end(addr, end); 248 if (pgd_none_or_clear_bad(pgd)) 249 continue; 250 free_pud_range(*tlb, pgd, addr, next, floor, ceiling); 251 } while (pgd++, addr = next, addr != end); 252 253 if (!(*tlb)->fullmm) 254 flush_tlb_pgtables((*tlb)->mm, start, end); 255} 256 257void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma, 258 unsigned long floor, unsigned long ceiling) 259{ 260 while (vma) { 261 struct vm_area_struct *next = vma->vm_next; 262 unsigned long addr = vma->vm_start; 263 264 /* 265 * Hide vma from rmap and vmtruncate before freeing pgtables 266 */ 267 anon_vma_unlink(vma); 268 unlink_file_vma(vma); 269 270 if (is_hugepage_only_range(vma->vm_mm, addr, HPAGE_SIZE)) { 271 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 272 floor, next? next->vm_start: ceiling); 273 } else { 274 /* 275 * Optimization: gather nearby vmas into one call down 276 */ 277 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 278 && !is_hugepage_only_range(vma->vm_mm, next->vm_start, 279 HPAGE_SIZE)) { 280 vma = next; 281 next = vma->vm_next; 282 anon_vma_unlink(vma); 283 unlink_file_vma(vma); 284 } 285 free_pgd_range(tlb, addr, vma->vm_end, 286 floor, next? next->vm_start: ceiling); 287 } 288 vma = next; 289 } 290} 291 292int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 293{ 294 struct page *new = pte_alloc_one(mm, address); 295 if (!new) 296 return -ENOMEM; 297 298 pte_lock_init(new); 299 spin_lock(&mm->page_table_lock); 300 if (pmd_present(*pmd)) { /* Another has populated it */ 301 pte_lock_deinit(new); 302 pte_free(new); 303 } else { 304 mm->nr_ptes++; 305 inc_page_state(nr_page_table_pages); 306 pmd_populate(mm, pmd, new); 307 } 308 spin_unlock(&mm->page_table_lock); 309 return 0; 310} 311 312int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 313{ 314 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 315 if (!new) 316 return -ENOMEM; 317 318 spin_lock(&init_mm.page_table_lock); 319 if (pmd_present(*pmd)) /* Another has populated it */ 320 pte_free_kernel(new); 321 else 322 pmd_populate_kernel(&init_mm, pmd, new); 323 spin_unlock(&init_mm.page_table_lock); 324 return 0; 325} 326 327static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) 328{ 329 if (file_rss) 330 add_mm_counter(mm, file_rss, file_rss); 331 if (anon_rss) 332 add_mm_counter(mm, anon_rss, anon_rss); 333} 334 335/* 336 * This function is called to print an error when a pte in a 337 * !VM_RESERVED region is found pointing to an invalid pfn (which 338 * is an error. 339 * 340 * The calling function must still handle the error. 341 */ 342void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr) 343{ 344 printk(KERN_ERR "Bad pte = %08llx, process = %s, " 345 "vm_flags = %lx, vaddr = %lx\n", 346 (long long)pte_val(pte), 347 (vma->vm_mm == current->mm ? current->comm : "???"), 348 vma->vm_flags, vaddr); 349 dump_stack(); 350} 351 352/* 353 * copy one vm_area from one task to the other. Assumes the page tables 354 * already present in the new task to be cleared in the whole range 355 * covered by this vma. 356 */ 357 358static inline void 359copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 360 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 361 unsigned long addr, int *rss) 362{ 363 unsigned long vm_flags = vma->vm_flags; 364 pte_t pte = *src_pte; 365 struct page *page; 366 unsigned long pfn; 367 368 /* pte contains position in swap or file, so copy. */ 369 if (unlikely(!pte_present(pte))) { 370 if (!pte_file(pte)) { 371 swap_duplicate(pte_to_swp_entry(pte)); 372 /* make sure dst_mm is on swapoff's mmlist. */ 373 if (unlikely(list_empty(&dst_mm->mmlist))) { 374 spin_lock(&mmlist_lock); 375 list_add(&dst_mm->mmlist, &src_mm->mmlist); 376 spin_unlock(&mmlist_lock); 377 } 378 } 379 goto out_set_pte; 380 } 381 382 /* If the region is VM_RESERVED, the mapping is not 383 * mapped via rmap - duplicate the pte as is. 384 */ 385 if (vm_flags & VM_RESERVED) 386 goto out_set_pte; 387 388 pfn = pte_pfn(pte); 389 /* If the pte points outside of valid memory but 390 * the region is not VM_RESERVED, we have a problem. 391 */ 392 if (unlikely(!pfn_valid(pfn))) { 393 print_bad_pte(vma, pte, addr); 394 goto out_set_pte; /* try to do something sane */ 395 } 396 397 page = pfn_to_page(pfn); 398 399 /* 400 * If it's a COW mapping, write protect it both 401 * in the parent and the child 402 */ 403 if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) { 404 ptep_set_wrprotect(src_mm, addr, src_pte); 405 pte = *src_pte; 406 } 407 408 /* 409 * If it's a shared mapping, mark it clean in 410 * the child 411 */ 412 if (vm_flags & VM_SHARED) 413 pte = pte_mkclean(pte); 414 pte = pte_mkold(pte); 415 get_page(page); 416 page_dup_rmap(page); 417 rss[!!PageAnon(page)]++; 418 419out_set_pte: 420 set_pte_at(dst_mm, addr, dst_pte, pte); 421} 422 423static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 424 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 425 unsigned long addr, unsigned long end) 426{ 427 pte_t *src_pte, *dst_pte; 428 spinlock_t *src_ptl, *dst_ptl; 429 int progress = 0; 430 int rss[2]; 431 432again: 433 rss[1] = rss[0] = 0; 434 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 435 if (!dst_pte) 436 return -ENOMEM; 437 src_pte = pte_offset_map_nested(src_pmd, addr); 438 src_ptl = pte_lockptr(src_mm, src_pmd); 439 spin_lock(src_ptl); 440 441 do { 442 /* 443 * We are holding two locks at this point - either of them 444 * could generate latencies in another task on another CPU. 445 */ 446 if (progress >= 32) { 447 progress = 0; 448 if (need_resched() || 449 need_lockbreak(src_ptl) || 450 need_lockbreak(dst_ptl)) 451 break; 452 } 453 if (pte_none(*src_pte)) { 454 progress++; 455 continue; 456 } 457 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 458 progress += 8; 459 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 460 461 spin_unlock(src_ptl); 462 pte_unmap_nested(src_pte - 1); 463 add_mm_rss(dst_mm, rss[0], rss[1]); 464 pte_unmap_unlock(dst_pte - 1, dst_ptl); 465 cond_resched(); 466 if (addr != end) 467 goto again; 468 return 0; 469} 470 471static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 472 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 473 unsigned long addr, unsigned long end) 474{ 475 pmd_t *src_pmd, *dst_pmd; 476 unsigned long next; 477 478 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 479 if (!dst_pmd) 480 return -ENOMEM; 481 src_pmd = pmd_offset(src_pud, addr); 482 do { 483 next = pmd_addr_end(addr, end); 484 if (pmd_none_or_clear_bad(src_pmd)) 485 continue; 486 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 487 vma, addr, next)) 488 return -ENOMEM; 489 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 490 return 0; 491} 492 493static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 494 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 495 unsigned long addr, unsigned long end) 496{ 497 pud_t *src_pud, *dst_pud; 498 unsigned long next; 499 500 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 501 if (!dst_pud) 502 return -ENOMEM; 503 src_pud = pud_offset(src_pgd, addr); 504 do { 505 next = pud_addr_end(addr, end); 506 if (pud_none_or_clear_bad(src_pud)) 507 continue; 508 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 509 vma, addr, next)) 510 return -ENOMEM; 511 } while (dst_pud++, src_pud++, addr = next, addr != end); 512 return 0; 513} 514 515int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 516 struct vm_area_struct *vma) 517{ 518 pgd_t *src_pgd, *dst_pgd; 519 unsigned long next; 520 unsigned long addr = vma->vm_start; 521 unsigned long end = vma->vm_end; 522 523 /* 524 * Don't copy ptes where a page fault will fill them correctly. 525 * Fork becomes much lighter when there are big shared or private 526 * readonly mappings. The tradeoff is that copy_page_range is more 527 * efficient than faulting. 528 */ 529 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_RESERVED))) { 530 if (!vma->anon_vma) 531 return 0; 532 } 533 534 if (is_vm_hugetlb_page(vma)) 535 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 536 537 dst_pgd = pgd_offset(dst_mm, addr); 538 src_pgd = pgd_offset(src_mm, addr); 539 do { 540 next = pgd_addr_end(addr, end); 541 if (pgd_none_or_clear_bad(src_pgd)) 542 continue; 543 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 544 vma, addr, next)) 545 return -ENOMEM; 546 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 547 return 0; 548} 549 550static void zap_pte_range(struct mmu_gather *tlb, 551 struct vm_area_struct *vma, pmd_t *pmd, 552 unsigned long addr, unsigned long end, 553 struct zap_details *details) 554{ 555 struct mm_struct *mm = tlb->mm; 556 pte_t *pte; 557 spinlock_t *ptl; 558 int file_rss = 0; 559 int anon_rss = 0; 560 561 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 562 do { 563 pte_t ptent = *pte; 564 if (pte_none(ptent)) 565 continue; 566 if (pte_present(ptent)) { 567 struct page *page = NULL; 568 if (!(vma->vm_flags & VM_RESERVED)) { 569 unsigned long pfn = pte_pfn(ptent); 570 if (unlikely(!pfn_valid(pfn))) 571 print_bad_pte(vma, ptent, addr); 572 else 573 page = pfn_to_page(pfn); 574 } 575 if (unlikely(details) && page) { 576 /* 577 * unmap_shared_mapping_pages() wants to 578 * invalidate cache without truncating: 579 * unmap shared but keep private pages. 580 */ 581 if (details->check_mapping && 582 details->check_mapping != page->mapping) 583 continue; 584 /* 585 * Each page->index must be checked when 586 * invalidating or truncating nonlinear. 587 */ 588 if (details->nonlinear_vma && 589 (page->index < details->first_index || 590 page->index > details->last_index)) 591 continue; 592 } 593 ptent = ptep_get_and_clear_full(mm, addr, pte, 594 tlb->fullmm); 595 tlb_remove_tlb_entry(tlb, pte, addr); 596 if (unlikely(!page)) 597 continue; 598 if (unlikely(details) && details->nonlinear_vma 599 && linear_page_index(details->nonlinear_vma, 600 addr) != page->index) 601 set_pte_at(mm, addr, pte, 602 pgoff_to_pte(page->index)); 603 if (PageAnon(page)) 604 anon_rss--; 605 else { 606 if (pte_dirty(ptent)) 607 set_page_dirty(page); 608 if (pte_young(ptent)) 609 mark_page_accessed(page); 610 file_rss--; 611 } 612 page_remove_rmap(page); 613 tlb_remove_page(tlb, page); 614 continue; 615 } 616 /* 617 * If details->check_mapping, we leave swap entries; 618 * if details->nonlinear_vma, we leave file entries. 619 */ 620 if (unlikely(details)) 621 continue; 622 if (!pte_file(ptent)) 623 free_swap_and_cache(pte_to_swp_entry(ptent)); 624 pte_clear_full(mm, addr, pte, tlb->fullmm); 625 } while (pte++, addr += PAGE_SIZE, addr != end); 626 627 add_mm_rss(mm, file_rss, anon_rss); 628 pte_unmap_unlock(pte - 1, ptl); 629} 630 631static inline void zap_pmd_range(struct mmu_gather *tlb, 632 struct vm_area_struct *vma, pud_t *pud, 633 unsigned long addr, unsigned long end, 634 struct zap_details *details) 635{ 636 pmd_t *pmd; 637 unsigned long next; 638 639 pmd = pmd_offset(pud, addr); 640 do { 641 next = pmd_addr_end(addr, end); 642 if (pmd_none_or_clear_bad(pmd)) 643 continue; 644 zap_pte_range(tlb, vma, pmd, addr, next, details); 645 } while (pmd++, addr = next, addr != end); 646} 647 648static inline void zap_pud_range(struct mmu_gather *tlb, 649 struct vm_area_struct *vma, pgd_t *pgd, 650 unsigned long addr, unsigned long end, 651 struct zap_details *details) 652{ 653 pud_t *pud; 654 unsigned long next; 655 656 pud = pud_offset(pgd, addr); 657 do { 658 next = pud_addr_end(addr, end); 659 if (pud_none_or_clear_bad(pud)) 660 continue; 661 zap_pmd_range(tlb, vma, pud, addr, next, details); 662 } while (pud++, addr = next, addr != end); 663} 664 665static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma, 666 unsigned long addr, unsigned long end, 667 struct zap_details *details) 668{ 669 pgd_t *pgd; 670 unsigned long next; 671 672 if (details && !details->check_mapping && !details->nonlinear_vma) 673 details = NULL; 674 675 BUG_ON(addr >= end); 676 tlb_start_vma(tlb, vma); 677 pgd = pgd_offset(vma->vm_mm, addr); 678 do { 679 next = pgd_addr_end(addr, end); 680 if (pgd_none_or_clear_bad(pgd)) 681 continue; 682 zap_pud_range(tlb, vma, pgd, addr, next, details); 683 } while (pgd++, addr = next, addr != end); 684 tlb_end_vma(tlb, vma); 685} 686 687#ifdef CONFIG_PREEMPT 688# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 689#else 690/* No preempt: go for improved straight-line efficiency */ 691# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 692#endif 693 694/** 695 * unmap_vmas - unmap a range of memory covered by a list of vma's 696 * @tlbp: address of the caller's struct mmu_gather 697 * @vma: the starting vma 698 * @start_addr: virtual address at which to start unmapping 699 * @end_addr: virtual address at which to end unmapping 700 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 701 * @details: details of nonlinear truncation or shared cache invalidation 702 * 703 * Returns the end address of the unmapping (restart addr if interrupted). 704 * 705 * Unmap all pages in the vma list. 706 * 707 * We aim to not hold locks for too long (for scheduling latency reasons). 708 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 709 * return the ending mmu_gather to the caller. 710 * 711 * Only addresses between `start' and `end' will be unmapped. 712 * 713 * The VMA list must be sorted in ascending virtual address order. 714 * 715 * unmap_vmas() assumes that the caller will flush the whole unmapped address 716 * range after unmap_vmas() returns. So the only responsibility here is to 717 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 718 * drops the lock and schedules. 719 */ 720unsigned long unmap_vmas(struct mmu_gather **tlbp, 721 struct vm_area_struct *vma, unsigned long start_addr, 722 unsigned long end_addr, unsigned long *nr_accounted, 723 struct zap_details *details) 724{ 725 unsigned long zap_bytes = ZAP_BLOCK_SIZE; 726 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 727 int tlb_start_valid = 0; 728 unsigned long start = start_addr; 729 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 730 int fullmm = (*tlbp)->fullmm; 731 732 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 733 unsigned long end; 734 735 start = max(vma->vm_start, start_addr); 736 if (start >= vma->vm_end) 737 continue; 738 end = min(vma->vm_end, end_addr); 739 if (end <= vma->vm_start) 740 continue; 741 742 if (vma->vm_flags & VM_ACCOUNT) 743 *nr_accounted += (end - start) >> PAGE_SHIFT; 744 745 while (start != end) { 746 unsigned long block; 747 748 if (!tlb_start_valid) { 749 tlb_start = start; 750 tlb_start_valid = 1; 751 } 752 753 if (is_vm_hugetlb_page(vma)) { 754 block = end - start; 755 unmap_hugepage_range(vma, start, end); 756 } else { 757 block = min(zap_bytes, end - start); 758 unmap_page_range(*tlbp, vma, start, 759 start + block, details); 760 } 761 762 start += block; 763 zap_bytes -= block; 764 if ((long)zap_bytes > 0) 765 continue; 766 767 tlb_finish_mmu(*tlbp, tlb_start, start); 768 769 if (need_resched() || 770 (i_mmap_lock && need_lockbreak(i_mmap_lock))) { 771 if (i_mmap_lock) { 772 *tlbp = NULL; 773 goto out; 774 } 775 cond_resched(); 776 } 777 778 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 779 tlb_start_valid = 0; 780 zap_bytes = ZAP_BLOCK_SIZE; 781 } 782 } 783out: 784 return start; /* which is now the end (or restart) address */ 785} 786 787/** 788 * zap_page_range - remove user pages in a given range 789 * @vma: vm_area_struct holding the applicable pages 790 * @address: starting address of pages to zap 791 * @size: number of bytes to zap 792 * @details: details of nonlinear truncation or shared cache invalidation 793 */ 794unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 795 unsigned long size, struct zap_details *details) 796{ 797 struct mm_struct *mm = vma->vm_mm; 798 struct mmu_gather *tlb; 799 unsigned long end = address + size; 800 unsigned long nr_accounted = 0; 801 802 lru_add_drain(); 803 tlb = tlb_gather_mmu(mm, 0); 804 update_hiwater_rss(mm); 805 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 806 if (tlb) 807 tlb_finish_mmu(tlb, address, end); 808 return end; 809} 810 811/* 812 * Do a quick page-table lookup for a single page. 813 */ 814struct page *follow_page(struct mm_struct *mm, unsigned long address, 815 unsigned int flags) 816{ 817 pgd_t *pgd; 818 pud_t *pud; 819 pmd_t *pmd; 820 pte_t *ptep, pte; 821 spinlock_t *ptl; 822 unsigned long pfn; 823 struct page *page; 824 825 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 826 if (!IS_ERR(page)) { 827 BUG_ON(flags & FOLL_GET); 828 goto out; 829 } 830 831 page = NULL; 832 pgd = pgd_offset(mm, address); 833 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 834 goto no_page_table; 835 836 pud = pud_offset(pgd, address); 837 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 838 goto no_page_table; 839 840 pmd = pmd_offset(pud, address); 841 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 842 goto no_page_table; 843 844 if (pmd_huge(*pmd)) { 845 BUG_ON(flags & FOLL_GET); 846 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 847 goto out; 848 } 849 850 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 851 if (!ptep) 852 goto out; 853 854 pte = *ptep; 855 if (!pte_present(pte)) 856 goto unlock; 857 if ((flags & FOLL_WRITE) && !pte_write(pte)) 858 goto unlock; 859 pfn = pte_pfn(pte); 860 if (!pfn_valid(pfn)) 861 goto unlock; 862 863 page = pfn_to_page(pfn); 864 if (flags & FOLL_GET) 865 get_page(page); 866 if (flags & FOLL_TOUCH) { 867 if ((flags & FOLL_WRITE) && 868 !pte_dirty(pte) && !PageDirty(page)) 869 set_page_dirty(page); 870 mark_page_accessed(page); 871 } 872unlock: 873 pte_unmap_unlock(ptep, ptl); 874out: 875 return page; 876 877no_page_table: 878 /* 879 * When core dumping an enormous anonymous area that nobody 880 * has touched so far, we don't want to allocate page tables. 881 */ 882 if (flags & FOLL_ANON) { 883 page = ZERO_PAGE(address); 884 if (flags & FOLL_GET) 885 get_page(page); 886 BUG_ON(flags & FOLL_WRITE); 887 } 888 return page; 889} 890 891int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 892 unsigned long start, int len, int write, int force, 893 struct page **pages, struct vm_area_struct **vmas) 894{ 895 int i; 896 unsigned int vm_flags; 897 898 /* 899 * Require read or write permissions. 900 * If 'force' is set, we only require the "MAY" flags. 901 */ 902 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 903 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 904 i = 0; 905 906 do { 907 struct vm_area_struct *vma; 908 unsigned int foll_flags; 909 910 vma = find_extend_vma(mm, start); 911 if (!vma && in_gate_area(tsk, start)) { 912 unsigned long pg = start & PAGE_MASK; 913 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 914 pgd_t *pgd; 915 pud_t *pud; 916 pmd_t *pmd; 917 pte_t *pte; 918 if (write) /* user gate pages are read-only */ 919 return i ? : -EFAULT; 920 if (pg > TASK_SIZE) 921 pgd = pgd_offset_k(pg); 922 else 923 pgd = pgd_offset_gate(mm, pg); 924 BUG_ON(pgd_none(*pgd)); 925 pud = pud_offset(pgd, pg); 926 BUG_ON(pud_none(*pud)); 927 pmd = pmd_offset(pud, pg); 928 if (pmd_none(*pmd)) 929 return i ? : -EFAULT; 930 pte = pte_offset_map(pmd, pg); 931 if (pte_none(*pte)) { 932 pte_unmap(pte); 933 return i ? : -EFAULT; 934 } 935 if (pages) { 936 pages[i] = pte_page(*pte); 937 get_page(pages[i]); 938 } 939 pte_unmap(pte); 940 if (vmas) 941 vmas[i] = gate_vma; 942 i++; 943 start += PAGE_SIZE; 944 len--; 945 continue; 946 } 947 948 if (!vma || (vma->vm_flags & (VM_IO | VM_RESERVED)) 949 || !(vm_flags & vma->vm_flags)) 950 return i ? : -EFAULT; 951 952 if (is_vm_hugetlb_page(vma)) { 953 i = follow_hugetlb_page(mm, vma, pages, vmas, 954 &start, &len, i); 955 continue; 956 } 957 958 foll_flags = FOLL_TOUCH; 959 if (pages) 960 foll_flags |= FOLL_GET; 961 if (!write && !(vma->vm_flags & VM_LOCKED) && 962 (!vma->vm_ops || !vma->vm_ops->nopage)) 963 foll_flags |= FOLL_ANON; 964 965 do { 966 struct page *page; 967 968 if (write) 969 foll_flags |= FOLL_WRITE; 970 971 cond_resched(); 972 while (!(page = follow_page(mm, start, foll_flags))) { 973 int ret; 974 ret = __handle_mm_fault(mm, vma, start, 975 foll_flags & FOLL_WRITE); 976 /* 977 * The VM_FAULT_WRITE bit tells us that do_wp_page has 978 * broken COW when necessary, even if maybe_mkwrite 979 * decided not to set pte_write. We can thus safely do 980 * subsequent page lookups as if they were reads. 981 */ 982 if (ret & VM_FAULT_WRITE) 983 foll_flags &= ~FOLL_WRITE; 984 985 switch (ret & ~VM_FAULT_WRITE) { 986 case VM_FAULT_MINOR: 987 tsk->min_flt++; 988 break; 989 case VM_FAULT_MAJOR: 990 tsk->maj_flt++; 991 break; 992 case VM_FAULT_SIGBUS: 993 return i ? i : -EFAULT; 994 case VM_FAULT_OOM: 995 return i ? i : -ENOMEM; 996 default: 997 BUG(); 998 } 999 } 1000 if (pages) { 1001 pages[i] = page; 1002 flush_dcache_page(page); 1003 } 1004 if (vmas) 1005 vmas[i] = vma; 1006 i++; 1007 start += PAGE_SIZE; 1008 len--; 1009 } while (len && start < vma->vm_end); 1010 } while (len); 1011 return i; 1012} 1013EXPORT_SYMBOL(get_user_pages); 1014 1015static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1016 unsigned long addr, unsigned long end, pgprot_t prot) 1017{ 1018 pte_t *pte; 1019 spinlock_t *ptl; 1020 1021 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1022 if (!pte) 1023 return -ENOMEM; 1024 do { 1025 struct page *page = ZERO_PAGE(addr); 1026 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot)); 1027 page_cache_get(page); 1028 page_add_file_rmap(page); 1029 inc_mm_counter(mm, file_rss); 1030 BUG_ON(!pte_none(*pte)); 1031 set_pte_at(mm, addr, pte, zero_pte); 1032 } while (pte++, addr += PAGE_SIZE, addr != end); 1033 pte_unmap_unlock(pte - 1, ptl); 1034 return 0; 1035} 1036 1037static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud, 1038 unsigned long addr, unsigned long end, pgprot_t prot) 1039{ 1040 pmd_t *pmd; 1041 unsigned long next; 1042 1043 pmd = pmd_alloc(mm, pud, addr); 1044 if (!pmd) 1045 return -ENOMEM; 1046 do { 1047 next = pmd_addr_end(addr, end); 1048 if (zeromap_pte_range(mm, pmd, addr, next, prot)) 1049 return -ENOMEM; 1050 } while (pmd++, addr = next, addr != end); 1051 return 0; 1052} 1053 1054static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1055 unsigned long addr, unsigned long end, pgprot_t prot) 1056{ 1057 pud_t *pud; 1058 unsigned long next; 1059 1060 pud = pud_alloc(mm, pgd, addr); 1061 if (!pud) 1062 return -ENOMEM; 1063 do { 1064 next = pud_addr_end(addr, end); 1065 if (zeromap_pmd_range(mm, pud, addr, next, prot)) 1066 return -ENOMEM; 1067 } while (pud++, addr = next, addr != end); 1068 return 0; 1069} 1070 1071int zeromap_page_range(struct vm_area_struct *vma, 1072 unsigned long addr, unsigned long size, pgprot_t prot) 1073{ 1074 pgd_t *pgd; 1075 unsigned long next; 1076 unsigned long end = addr + size; 1077 struct mm_struct *mm = vma->vm_mm; 1078 int err; 1079 1080 BUG_ON(addr >= end); 1081 pgd = pgd_offset(mm, addr); 1082 flush_cache_range(vma, addr, end); 1083 do { 1084 next = pgd_addr_end(addr, end); 1085 err = zeromap_pud_range(mm, pgd, addr, next, prot); 1086 if (err) 1087 break; 1088 } while (pgd++, addr = next, addr != end); 1089 return err; 1090} 1091 1092/* 1093 * maps a range of physical memory into the requested pages. the old 1094 * mappings are removed. any references to nonexistent pages results 1095 * in null mappings (currently treated as "copy-on-access") 1096 */ 1097static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1098 unsigned long addr, unsigned long end, 1099 unsigned long pfn, pgprot_t prot) 1100{ 1101 pte_t *pte; 1102 spinlock_t *ptl; 1103 1104 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1105 if (!pte) 1106 return -ENOMEM; 1107 do { 1108 BUG_ON(!pte_none(*pte)); 1109 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); 1110 pfn++; 1111 } while (pte++, addr += PAGE_SIZE, addr != end); 1112 pte_unmap_unlock(pte - 1, ptl); 1113 return 0; 1114} 1115 1116static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1117 unsigned long addr, unsigned long end, 1118 unsigned long pfn, pgprot_t prot) 1119{ 1120 pmd_t *pmd; 1121 unsigned long next; 1122 1123 pfn -= addr >> PAGE_SHIFT; 1124 pmd = pmd_alloc(mm, pud, addr); 1125 if (!pmd) 1126 return -ENOMEM; 1127 do { 1128 next = pmd_addr_end(addr, end); 1129 if (remap_pte_range(mm, pmd, addr, next, 1130 pfn + (addr >> PAGE_SHIFT), prot)) 1131 return -ENOMEM; 1132 } while (pmd++, addr = next, addr != end); 1133 return 0; 1134} 1135 1136static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1137 unsigned long addr, unsigned long end, 1138 unsigned long pfn, pgprot_t prot) 1139{ 1140 pud_t *pud; 1141 unsigned long next; 1142 1143 pfn -= addr >> PAGE_SHIFT; 1144 pud = pud_alloc(mm, pgd, addr); 1145 if (!pud) 1146 return -ENOMEM; 1147 do { 1148 next = pud_addr_end(addr, end); 1149 if (remap_pmd_range(mm, pud, addr, next, 1150 pfn + (addr >> PAGE_SHIFT), prot)) 1151 return -ENOMEM; 1152 } while (pud++, addr = next, addr != end); 1153 return 0; 1154} 1155 1156/* Note: this is only safe if the mm semaphore is held when called. */ 1157int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1158 unsigned long pfn, unsigned long size, pgprot_t prot) 1159{ 1160 pgd_t *pgd; 1161 unsigned long next; 1162 unsigned long end = addr + PAGE_ALIGN(size); 1163 struct mm_struct *mm = vma->vm_mm; 1164 int err; 1165 1166 /* 1167 * Physically remapped pages are special. Tell the 1168 * rest of the world about it: 1169 * VM_IO tells people not to look at these pages 1170 * (accesses can have side effects). 1171 * VM_RESERVED tells the core MM not to "manage" these pages 1172 * (e.g. refcount, mapcount, try to swap them out). 1173 */ 1174 vma->vm_flags |= VM_IO | VM_RESERVED; 1175 1176 BUG_ON(addr >= end); 1177 pfn -= addr >> PAGE_SHIFT; 1178 pgd = pgd_offset(mm, addr); 1179 flush_cache_range(vma, addr, end); 1180 do { 1181 next = pgd_addr_end(addr, end); 1182 err = remap_pud_range(mm, pgd, addr, next, 1183 pfn + (addr >> PAGE_SHIFT), prot); 1184 if (err) 1185 break; 1186 } while (pgd++, addr = next, addr != end); 1187 return err; 1188} 1189EXPORT_SYMBOL(remap_pfn_range); 1190 1191/* 1192 * handle_pte_fault chooses page fault handler according to an entry 1193 * which was read non-atomically. Before making any commitment, on 1194 * those architectures or configurations (e.g. i386 with PAE) which 1195 * might give a mix of unmatched parts, do_swap_page and do_file_page 1196 * must check under lock before unmapping the pte and proceeding 1197 * (but do_wp_page is only called after already making such a check; 1198 * and do_anonymous_page and do_no_page can safely check later on). 1199 */ 1200static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1201 pte_t *page_table, pte_t orig_pte) 1202{ 1203 int same = 1; 1204#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1205 if (sizeof(pte_t) > sizeof(unsigned long)) { 1206 spinlock_t *ptl = pte_lockptr(mm, pmd); 1207 spin_lock(ptl); 1208 same = pte_same(*page_table, orig_pte); 1209 spin_unlock(ptl); 1210 } 1211#endif 1212 pte_unmap(page_table); 1213 return same; 1214} 1215 1216/* 1217 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1218 * servicing faults for write access. In the normal case, do always want 1219 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1220 * that do not have writing enabled, when used by access_process_vm. 1221 */ 1222static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1223{ 1224 if (likely(vma->vm_flags & VM_WRITE)) 1225 pte = pte_mkwrite(pte); 1226 return pte; 1227} 1228 1229/* 1230 * This routine handles present pages, when users try to write 1231 * to a shared page. It is done by copying the page to a new address 1232 * and decrementing the shared-page counter for the old page. 1233 * 1234 * Note that this routine assumes that the protection checks have been 1235 * done by the caller (the low-level page fault routine in most cases). 1236 * Thus we can safely just mark it writable once we've done any necessary 1237 * COW. 1238 * 1239 * We also mark the page dirty at this point even though the page will 1240 * change only once the write actually happens. This avoids a few races, 1241 * and potentially makes it more efficient. 1242 * 1243 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1244 * but allow concurrent faults), with pte both mapped and locked. 1245 * We return with mmap_sem still held, but pte unmapped and unlocked. 1246 */ 1247static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1248 unsigned long address, pte_t *page_table, pmd_t *pmd, 1249 spinlock_t *ptl, pte_t orig_pte) 1250{ 1251 struct page *old_page, *new_page; 1252 unsigned long pfn = pte_pfn(orig_pte); 1253 pte_t entry; 1254 int ret = VM_FAULT_MINOR; 1255 1256 BUG_ON(vma->vm_flags & VM_RESERVED); 1257 1258 if (unlikely(!pfn_valid(pfn))) { 1259 /* 1260 * Page table corrupted: show pte and kill process. 1261 */ 1262 print_bad_pte(vma, orig_pte, address); 1263 ret = VM_FAULT_OOM; 1264 goto unlock; 1265 } 1266 old_page = pfn_to_page(pfn); 1267 1268 if (PageAnon(old_page) && !TestSetPageLocked(old_page)) { 1269 int reuse = can_share_swap_page(old_page); 1270 unlock_page(old_page); 1271 if (reuse) { 1272 flush_cache_page(vma, address, pfn); 1273 entry = pte_mkyoung(orig_pte); 1274 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1275 ptep_set_access_flags(vma, address, page_table, entry, 1); 1276 update_mmu_cache(vma, address, entry); 1277 lazy_mmu_prot_update(entry); 1278 ret |= VM_FAULT_WRITE; 1279 goto unlock; 1280 } 1281 } 1282 1283 /* 1284 * Ok, we need to copy. Oh, well.. 1285 */ 1286 page_cache_get(old_page); 1287 pte_unmap_unlock(page_table, ptl); 1288 1289 if (unlikely(anon_vma_prepare(vma))) 1290 goto oom; 1291 if (old_page == ZERO_PAGE(address)) { 1292 new_page = alloc_zeroed_user_highpage(vma, address); 1293 if (!new_page) 1294 goto oom; 1295 } else { 1296 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); 1297 if (!new_page) 1298 goto oom; 1299 copy_user_highpage(new_page, old_page, address); 1300 } 1301 1302 /* 1303 * Re-check the pte - we dropped the lock 1304 */ 1305 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1306 if (likely(pte_same(*page_table, orig_pte))) { 1307 page_remove_rmap(old_page); 1308 if (!PageAnon(old_page)) { 1309 inc_mm_counter(mm, anon_rss); 1310 dec_mm_counter(mm, file_rss); 1311 } 1312 flush_cache_page(vma, address, pfn); 1313 entry = mk_pte(new_page, vma->vm_page_prot); 1314 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1315 ptep_establish(vma, address, page_table, entry); 1316 update_mmu_cache(vma, address, entry); 1317 lazy_mmu_prot_update(entry); 1318 lru_cache_add_active(new_page); 1319 page_add_anon_rmap(new_page, vma, address); 1320 1321 /* Free the old page.. */ 1322 new_page = old_page; 1323 ret |= VM_FAULT_WRITE; 1324 } 1325 page_cache_release(new_page); 1326 page_cache_release(old_page); 1327unlock: 1328 pte_unmap_unlock(page_table, ptl); 1329 return ret; 1330oom: 1331 page_cache_release(old_page); 1332 return VM_FAULT_OOM; 1333} 1334 1335/* 1336 * Helper functions for unmap_mapping_range(). 1337 * 1338 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 1339 * 1340 * We have to restart searching the prio_tree whenever we drop the lock, 1341 * since the iterator is only valid while the lock is held, and anyway 1342 * a later vma might be split and reinserted earlier while lock dropped. 1343 * 1344 * The list of nonlinear vmas could be handled more efficiently, using 1345 * a placeholder, but handle it in the same way until a need is shown. 1346 * It is important to search the prio_tree before nonlinear list: a vma 1347 * may become nonlinear and be shifted from prio_tree to nonlinear list 1348 * while the lock is dropped; but never shifted from list to prio_tree. 1349 * 1350 * In order to make forward progress despite restarting the search, 1351 * vm_truncate_count is used to mark a vma as now dealt with, so we can 1352 * quickly skip it next time around. Since the prio_tree search only 1353 * shows us those vmas affected by unmapping the range in question, we 1354 * can't efficiently keep all vmas in step with mapping->truncate_count: 1355 * so instead reset them all whenever it wraps back to 0 (then go to 1). 1356 * mapping->truncate_count and vma->vm_truncate_count are protected by 1357 * i_mmap_lock. 1358 * 1359 * In order to make forward progress despite repeatedly restarting some 1360 * large vma, note the restart_addr from unmap_vmas when it breaks out: 1361 * and restart from that address when we reach that vma again. It might 1362 * have been split or merged, shrunk or extended, but never shifted: so 1363 * restart_addr remains valid so long as it remains in the vma's range. 1364 * unmap_mapping_range forces truncate_count to leap over page-aligned 1365 * values so we can save vma's restart_addr in its truncate_count field. 1366 */ 1367#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 1368 1369static void reset_vma_truncate_counts(struct address_space *mapping) 1370{ 1371 struct vm_area_struct *vma; 1372 struct prio_tree_iter iter; 1373 1374 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 1375 vma->vm_truncate_count = 0; 1376 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 1377 vma->vm_truncate_count = 0; 1378} 1379 1380static int unmap_mapping_range_vma(struct vm_area_struct *vma, 1381 unsigned long start_addr, unsigned long end_addr, 1382 struct zap_details *details) 1383{ 1384 unsigned long restart_addr; 1385 int need_break; 1386 1387again: 1388 restart_addr = vma->vm_truncate_count; 1389 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 1390 start_addr = restart_addr; 1391 if (start_addr >= end_addr) { 1392 /* Top of vma has been split off since last time */ 1393 vma->vm_truncate_count = details->truncate_count; 1394 return 0; 1395 } 1396 } 1397 1398 restart_addr = zap_page_range(vma, start_addr, 1399 end_addr - start_addr, details); 1400 need_break = need_resched() || 1401 need_lockbreak(details->i_mmap_lock); 1402 1403 if (restart_addr >= end_addr) { 1404 /* We have now completed this vma: mark it so */ 1405 vma->vm_truncate_count = details->truncate_count; 1406 if (!need_break) 1407 return 0; 1408 } else { 1409 /* Note restart_addr in vma's truncate_count field */ 1410 vma->vm_truncate_count = restart_addr; 1411 if (!need_break) 1412 goto again; 1413 } 1414 1415 spin_unlock(details->i_mmap_lock); 1416 cond_resched(); 1417 spin_lock(details->i_mmap_lock); 1418 return -EINTR; 1419} 1420 1421static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 1422 struct zap_details *details) 1423{ 1424 struct vm_area_struct *vma; 1425 struct prio_tree_iter iter; 1426 pgoff_t vba, vea, zba, zea; 1427 1428restart: 1429 vma_prio_tree_foreach(vma, &iter, root, 1430 details->first_index, details->last_index) { 1431 /* Skip quickly over those we have already dealt with */ 1432 if (vma->vm_truncate_count == details->truncate_count) 1433 continue; 1434 1435 vba = vma->vm_pgoff; 1436 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 1437 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 1438 zba = details->first_index; 1439 if (zba < vba) 1440 zba = vba; 1441 zea = details->last_index; 1442 if (zea > vea) 1443 zea = vea; 1444 1445 if (unmap_mapping_range_vma(vma, 1446 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 1447 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 1448 details) < 0) 1449 goto restart; 1450 } 1451} 1452 1453static inline void unmap_mapping_range_list(struct list_head *head, 1454 struct zap_details *details) 1455{ 1456 struct vm_area_struct *vma; 1457 1458 /* 1459 * In nonlinear VMAs there is no correspondence between virtual address 1460 * offset and file offset. So we must perform an exhaustive search 1461 * across *all* the pages in each nonlinear VMA, not just the pages 1462 * whose virtual address lies outside the file truncation point. 1463 */ 1464restart: 1465 list_for_each_entry(vma, head, shared.vm_set.list) { 1466 /* Skip quickly over those we have already dealt with */ 1467 if (vma->vm_truncate_count == details->truncate_count) 1468 continue; 1469 details->nonlinear_vma = vma; 1470 if (unmap_mapping_range_vma(vma, vma->vm_start, 1471 vma->vm_end, details) < 0) 1472 goto restart; 1473 } 1474} 1475 1476/** 1477 * unmap_mapping_range - unmap the portion of all mmaps 1478 * in the specified address_space corresponding to the specified 1479 * page range in the underlying file. 1480 * @mapping: the address space containing mmaps to be unmapped. 1481 * @holebegin: byte in first page to unmap, relative to the start of 1482 * the underlying file. This will be rounded down to a PAGE_SIZE 1483 * boundary. Note that this is different from vmtruncate(), which 1484 * must keep the partial page. In contrast, we must get rid of 1485 * partial pages. 1486 * @holelen: size of prospective hole in bytes. This will be rounded 1487 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 1488 * end of the file. 1489 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 1490 * but 0 when invalidating pagecache, don't throw away private data. 1491 */ 1492void unmap_mapping_range(struct address_space *mapping, 1493 loff_t const holebegin, loff_t const holelen, int even_cows) 1494{ 1495 struct zap_details details; 1496 pgoff_t hba = holebegin >> PAGE_SHIFT; 1497 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1498 1499 /* Check for overflow. */ 1500 if (sizeof(holelen) > sizeof(hlen)) { 1501 long long holeend = 1502 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1503 if (holeend & ~(long long)ULONG_MAX) 1504 hlen = ULONG_MAX - hba + 1; 1505 } 1506 1507 details.check_mapping = even_cows? NULL: mapping; 1508 details.nonlinear_vma = NULL; 1509 details.first_index = hba; 1510 details.last_index = hba + hlen - 1; 1511 if (details.last_index < details.first_index) 1512 details.last_index = ULONG_MAX; 1513 details.i_mmap_lock = &mapping->i_mmap_lock; 1514 1515 spin_lock(&mapping->i_mmap_lock); 1516 1517 /* serialize i_size write against truncate_count write */ 1518 smp_wmb(); 1519 /* Protect against page faults, and endless unmapping loops */ 1520 mapping->truncate_count++; 1521 /* 1522 * For archs where spin_lock has inclusive semantics like ia64 1523 * this smp_mb() will prevent to read pagetable contents 1524 * before the truncate_count increment is visible to 1525 * other cpus. 1526 */ 1527 smp_mb(); 1528 if (unlikely(is_restart_addr(mapping->truncate_count))) { 1529 if (mapping->truncate_count == 0) 1530 reset_vma_truncate_counts(mapping); 1531 mapping->truncate_count++; 1532 } 1533 details.truncate_count = mapping->truncate_count; 1534 1535 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 1536 unmap_mapping_range_tree(&mapping->i_mmap, &details); 1537 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 1538 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 1539 spin_unlock(&mapping->i_mmap_lock); 1540} 1541EXPORT_SYMBOL(unmap_mapping_range); 1542 1543/* 1544 * Handle all mappings that got truncated by a "truncate()" 1545 * system call. 1546 * 1547 * NOTE! We have to be ready to update the memory sharing 1548 * between the file and the memory map for a potential last 1549 * incomplete page. Ugly, but necessary. 1550 */ 1551int vmtruncate(struct inode * inode, loff_t offset) 1552{ 1553 struct address_space *mapping = inode->i_mapping; 1554 unsigned long limit; 1555 1556 if (inode->i_size < offset) 1557 goto do_expand; 1558 /* 1559 * truncation of in-use swapfiles is disallowed - it would cause 1560 * subsequent swapout to scribble on the now-freed blocks. 1561 */ 1562 if (IS_SWAPFILE(inode)) 1563 goto out_busy; 1564 i_size_write(inode, offset); 1565 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1566 truncate_inode_pages(mapping, offset); 1567 goto out_truncate; 1568 1569do_expand: 1570 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1571 if (limit != RLIM_INFINITY && offset > limit) 1572 goto out_sig; 1573 if (offset > inode->i_sb->s_maxbytes) 1574 goto out_big; 1575 i_size_write(inode, offset); 1576 1577out_truncate: 1578 if (inode->i_op && inode->i_op->truncate) 1579 inode->i_op->truncate(inode); 1580 return 0; 1581out_sig: 1582 send_sig(SIGXFSZ, current, 0); 1583out_big: 1584 return -EFBIG; 1585out_busy: 1586 return -ETXTBSY; 1587} 1588 1589EXPORT_SYMBOL(vmtruncate); 1590 1591/* 1592 * Primitive swap readahead code. We simply read an aligned block of 1593 * (1 << page_cluster) entries in the swap area. This method is chosen 1594 * because it doesn't cost us any seek time. We also make sure to queue 1595 * the 'original' request together with the readahead ones... 1596 * 1597 * This has been extended to use the NUMA policies from the mm triggering 1598 * the readahead. 1599 * 1600 * Caller must hold down_read on the vma->vm_mm if vma is not NULL. 1601 */ 1602void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) 1603{ 1604#ifdef CONFIG_NUMA 1605 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; 1606#endif 1607 int i, num; 1608 struct page *new_page; 1609 unsigned long offset; 1610 1611 /* 1612 * Get the number of handles we should do readahead io to. 1613 */ 1614 num = valid_swaphandles(entry, &offset); 1615 for (i = 0; i < num; offset++, i++) { 1616 /* Ok, do the async read-ahead now */ 1617 new_page = read_swap_cache_async(swp_entry(swp_type(entry), 1618 offset), vma, addr); 1619 if (!new_page) 1620 break; 1621 page_cache_release(new_page); 1622#ifdef CONFIG_NUMA 1623 /* 1624 * Find the next applicable VMA for the NUMA policy. 1625 */ 1626 addr += PAGE_SIZE; 1627 if (addr == 0) 1628 vma = NULL; 1629 if (vma) { 1630 if (addr >= vma->vm_end) { 1631 vma = next_vma; 1632 next_vma = vma ? vma->vm_next : NULL; 1633 } 1634 if (vma && addr < vma->vm_start) 1635 vma = NULL; 1636 } else { 1637 if (next_vma && addr >= next_vma->vm_start) { 1638 vma = next_vma; 1639 next_vma = vma->vm_next; 1640 } 1641 } 1642#endif 1643 } 1644 lru_add_drain(); /* Push any new pages onto the LRU now */ 1645} 1646 1647/* 1648 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1649 * but allow concurrent faults), and pte mapped but not yet locked. 1650 * We return with mmap_sem still held, but pte unmapped and unlocked. 1651 */ 1652static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 1653 unsigned long address, pte_t *page_table, pmd_t *pmd, 1654 int write_access, pte_t orig_pte) 1655{ 1656 spinlock_t *ptl; 1657 struct page *page; 1658 swp_entry_t entry; 1659 pte_t pte; 1660 int ret = VM_FAULT_MINOR; 1661 1662 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 1663 goto out; 1664 1665 entry = pte_to_swp_entry(orig_pte); 1666 page = lookup_swap_cache(entry); 1667 if (!page) { 1668 swapin_readahead(entry, address, vma); 1669 page = read_swap_cache_async(entry, vma, address); 1670 if (!page) { 1671 /* 1672 * Back out if somebody else faulted in this pte 1673 * while we released the pte lock. 1674 */ 1675 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1676 if (likely(pte_same(*page_table, orig_pte))) 1677 ret = VM_FAULT_OOM; 1678 goto unlock; 1679 } 1680 1681 /* Had to read the page from swap area: Major fault */ 1682 ret = VM_FAULT_MAJOR; 1683 inc_page_state(pgmajfault); 1684 grab_swap_token(); 1685 } 1686 1687 mark_page_accessed(page); 1688 lock_page(page); 1689 1690 /* 1691 * Back out if somebody else already faulted in this pte. 1692 */ 1693 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1694 if (unlikely(!pte_same(*page_table, orig_pte))) 1695 goto out_nomap; 1696 1697 if (unlikely(!PageUptodate(page))) { 1698 ret = VM_FAULT_SIGBUS; 1699 goto out_nomap; 1700 } 1701 1702 /* The page isn't present yet, go ahead with the fault. */ 1703 1704 inc_mm_counter(mm, anon_rss); 1705 pte = mk_pte(page, vma->vm_page_prot); 1706 if (write_access && can_share_swap_page(page)) { 1707 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 1708 write_access = 0; 1709 } 1710 1711 flush_icache_page(vma, page); 1712 set_pte_at(mm, address, page_table, pte); 1713 page_add_anon_rmap(page, vma, address); 1714 1715 swap_free(entry); 1716 if (vm_swap_full()) 1717 remove_exclusive_swap_page(page); 1718 unlock_page(page); 1719 1720 if (write_access) { 1721 if (do_wp_page(mm, vma, address, 1722 page_table, pmd, ptl, pte) == VM_FAULT_OOM) 1723 ret = VM_FAULT_OOM; 1724 goto out; 1725 } 1726 1727 /* No need to invalidate - it was non-present before */ 1728 update_mmu_cache(vma, address, pte); 1729 lazy_mmu_prot_update(pte); 1730unlock: 1731 pte_unmap_unlock(page_table, ptl); 1732out: 1733 return ret; 1734out_nomap: 1735 pte_unmap_unlock(page_table, ptl); 1736 unlock_page(page); 1737 page_cache_release(page); 1738 return ret; 1739} 1740 1741/* 1742 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1743 * but allow concurrent faults), and pte mapped but not yet locked. 1744 * We return with mmap_sem still held, but pte unmapped and unlocked. 1745 */ 1746static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 1747 unsigned long address, pte_t *page_table, pmd_t *pmd, 1748 int write_access) 1749{ 1750 struct page *page; 1751 spinlock_t *ptl; 1752 pte_t entry; 1753 1754 if (write_access) { 1755 /* Allocate our own private page. */ 1756 pte_unmap(page_table); 1757 1758 if (unlikely(anon_vma_prepare(vma))) 1759 goto oom; 1760 page = alloc_zeroed_user_highpage(vma, address); 1761 if (!page) 1762 goto oom; 1763 1764 entry = mk_pte(page, vma->vm_page_prot); 1765 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1766 1767 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1768 if (!pte_none(*page_table)) 1769 goto release; 1770 inc_mm_counter(mm, anon_rss); 1771 lru_cache_add_active(page); 1772 SetPageReferenced(page); 1773 page_add_anon_rmap(page, vma, address); 1774 } else { 1775 /* Map the ZERO_PAGE - vm_page_prot is readonly */ 1776 page = ZERO_PAGE(address); 1777 page_cache_get(page); 1778 entry = mk_pte(page, vma->vm_page_prot); 1779 1780 ptl = pte_lockptr(mm, pmd); 1781 spin_lock(ptl); 1782 if (!pte_none(*page_table)) 1783 goto release; 1784 inc_mm_counter(mm, file_rss); 1785 page_add_file_rmap(page); 1786 } 1787 1788 set_pte_at(mm, address, page_table, entry); 1789 1790 /* No need to invalidate - it was non-present before */ 1791 update_mmu_cache(vma, address, entry); 1792 lazy_mmu_prot_update(entry); 1793unlock: 1794 pte_unmap_unlock(page_table, ptl); 1795 return VM_FAULT_MINOR; 1796release: 1797 page_cache_release(page); 1798 goto unlock; 1799oom: 1800 return VM_FAULT_OOM; 1801} 1802 1803/* 1804 * do_no_page() tries to create a new page mapping. It aggressively 1805 * tries to share with existing pages, but makes a separate copy if 1806 * the "write_access" parameter is true in order to avoid the next 1807 * page fault. 1808 * 1809 * As this is called only for pages that do not currently exist, we 1810 * do not need to flush old virtual caches or the TLB. 1811 * 1812 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1813 * but allow concurrent faults), and pte mapped but not yet locked. 1814 * We return with mmap_sem still held, but pte unmapped and unlocked. 1815 */ 1816static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 1817 unsigned long address, pte_t *page_table, pmd_t *pmd, 1818 int write_access) 1819{ 1820 spinlock_t *ptl; 1821 struct page *new_page; 1822 struct address_space *mapping = NULL; 1823 pte_t entry; 1824 unsigned int sequence = 0; 1825 int ret = VM_FAULT_MINOR; 1826 int anon = 0; 1827 1828 pte_unmap(page_table); 1829 1830 if (vma->vm_file) { 1831 mapping = vma->vm_file->f_mapping; 1832 sequence = mapping->truncate_count; 1833 smp_rmb(); /* serializes i_size against truncate_count */ 1834 } 1835retry: 1836 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); 1837 /* 1838 * No smp_rmb is needed here as long as there's a full 1839 * spin_lock/unlock sequence inside the ->nopage callback 1840 * (for the pagecache lookup) that acts as an implicit 1841 * smp_mb() and prevents the i_size read to happen 1842 * after the next truncate_count read. 1843 */ 1844 1845 /* no page was available -- either SIGBUS or OOM */ 1846 if (new_page == NOPAGE_SIGBUS) 1847 return VM_FAULT_SIGBUS; 1848 if (new_page == NOPAGE_OOM) 1849 return VM_FAULT_OOM; 1850 1851 /* 1852 * Should we do an early C-O-W break? 1853 */ 1854 if (write_access && !(vma->vm_flags & VM_SHARED)) { 1855 struct page *page; 1856 1857 if (unlikely(anon_vma_prepare(vma))) 1858 goto oom; 1859 page = alloc_page_vma(GFP_HIGHUSER, vma, address); 1860 if (!page) 1861 goto oom; 1862 copy_user_highpage(page, new_page, address); 1863 page_cache_release(new_page); 1864 new_page = page; 1865 anon = 1; 1866 } 1867 1868 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1869 /* 1870 * For a file-backed vma, someone could have truncated or otherwise 1871 * invalidated this page. If unmap_mapping_range got called, 1872 * retry getting the page. 1873 */ 1874 if (mapping && unlikely(sequence != mapping->truncate_count)) { 1875 pte_unmap_unlock(page_table, ptl); 1876 page_cache_release(new_page); 1877 cond_resched(); 1878 sequence = mapping->truncate_count; 1879 smp_rmb(); 1880 goto retry; 1881 } 1882 1883 /* 1884 * This silly early PAGE_DIRTY setting removes a race 1885 * due to the bad i386 page protection. But it's valid 1886 * for other architectures too. 1887 * 1888 * Note that if write_access is true, we either now have 1889 * an exclusive copy of the page, or this is a shared mapping, 1890 * so we can make it writable and dirty to avoid having to 1891 * handle that later. 1892 */ 1893 /* Only go through if we didn't race with anybody else... */ 1894 if (pte_none(*page_table)) { 1895 flush_icache_page(vma, new_page); 1896 entry = mk_pte(new_page, vma->vm_page_prot); 1897 if (write_access) 1898 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1899 set_pte_at(mm, address, page_table, entry); 1900 if (anon) { 1901 inc_mm_counter(mm, anon_rss); 1902 lru_cache_add_active(new_page); 1903 page_add_anon_rmap(new_page, vma, address); 1904 } else if (!(vma->vm_flags & VM_RESERVED)) { 1905 inc_mm_counter(mm, file_rss); 1906 page_add_file_rmap(new_page); 1907 } 1908 } else { 1909 /* One of our sibling threads was faster, back out. */ 1910 page_cache_release(new_page); 1911 goto unlock; 1912 } 1913 1914 /* no need to invalidate: a not-present page shouldn't be cached */ 1915 update_mmu_cache(vma, address, entry); 1916 lazy_mmu_prot_update(entry); 1917unlock: 1918 pte_unmap_unlock(page_table, ptl); 1919 return ret; 1920oom: 1921 page_cache_release(new_page); 1922 return VM_FAULT_OOM; 1923} 1924 1925/* 1926 * Fault of a previously existing named mapping. Repopulate the pte 1927 * from the encoded file_pte if possible. This enables swappable 1928 * nonlinear vmas. 1929 * 1930 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1931 * but allow concurrent faults), and pte mapped but not yet locked. 1932 * We return with mmap_sem still held, but pte unmapped and unlocked. 1933 */ 1934static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma, 1935 unsigned long address, pte_t *page_table, pmd_t *pmd, 1936 int write_access, pte_t orig_pte) 1937{ 1938 pgoff_t pgoff; 1939 int err; 1940 1941 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 1942 return VM_FAULT_MINOR; 1943 1944 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 1945 /* 1946 * Page table corrupted: show pte and kill process. 1947 */ 1948 print_bad_pte(vma, orig_pte, address); 1949 return VM_FAULT_OOM; 1950 } 1951 /* We can then assume vm->vm_ops && vma->vm_ops->populate */ 1952 1953 pgoff = pte_to_pgoff(orig_pte); 1954 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, 1955 vma->vm_page_prot, pgoff, 0); 1956 if (err == -ENOMEM) 1957 return VM_FAULT_OOM; 1958 if (err) 1959 return VM_FAULT_SIGBUS; 1960 return VM_FAULT_MAJOR; 1961} 1962 1963/* 1964 * These routines also need to handle stuff like marking pages dirty 1965 * and/or accessed for architectures that don't do it in hardware (most 1966 * RISC architectures). The early dirtying is also good on the i386. 1967 * 1968 * There is also a hook called "update_mmu_cache()" that architectures 1969 * with external mmu caches can use to update those (ie the Sparc or 1970 * PowerPC hashed page tables that act as extended TLBs). 1971 * 1972 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1973 * but allow concurrent faults), and pte mapped but not yet locked. 1974 * We return with mmap_sem still held, but pte unmapped and unlocked. 1975 */ 1976static inline int handle_pte_fault(struct mm_struct *mm, 1977 struct vm_area_struct *vma, unsigned long address, 1978 pte_t *pte, pmd_t *pmd, int write_access) 1979{ 1980 pte_t entry; 1981 spinlock_t *ptl; 1982 1983 entry = *pte; 1984 if (!pte_present(entry)) { 1985 if (pte_none(entry)) { 1986 if (!vma->vm_ops || !vma->vm_ops->nopage) 1987 return do_anonymous_page(mm, vma, address, 1988 pte, pmd, write_access); 1989 return do_no_page(mm, vma, address, 1990 pte, pmd, write_access); 1991 } 1992 if (pte_file(entry)) 1993 return do_file_page(mm, vma, address, 1994 pte, pmd, write_access, entry); 1995 return do_swap_page(mm, vma, address, 1996 pte, pmd, write_access, entry); 1997 } 1998 1999 ptl = pte_lockptr(mm, pmd); 2000 spin_lock(ptl); 2001 if (unlikely(!pte_same(*pte, entry))) 2002 goto unlock; 2003 if (write_access) { 2004 if (!pte_write(entry)) 2005 return do_wp_page(mm, vma, address, 2006 pte, pmd, ptl, entry); 2007 entry = pte_mkdirty(entry); 2008 } 2009 entry = pte_mkyoung(entry); 2010 ptep_set_access_flags(vma, address, pte, entry, write_access); 2011 update_mmu_cache(vma, address, entry); 2012 lazy_mmu_prot_update(entry); 2013unlock: 2014 pte_unmap_unlock(pte, ptl); 2015 return VM_FAULT_MINOR; 2016} 2017 2018/* 2019 * By the time we get here, we already hold the mm semaphore 2020 */ 2021int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2022 unsigned long address, int write_access) 2023{ 2024 pgd_t *pgd; 2025 pud_t *pud; 2026 pmd_t *pmd; 2027 pte_t *pte; 2028 2029 __set_current_state(TASK_RUNNING); 2030 2031 inc_page_state(pgfault); 2032 2033 if (unlikely(is_vm_hugetlb_page(vma))) 2034 return hugetlb_fault(mm, vma, address, write_access); 2035 2036 pgd = pgd_offset(mm, address); 2037 pud = pud_alloc(mm, pgd, address); 2038 if (!pud) 2039 return VM_FAULT_OOM; 2040 pmd = pmd_alloc(mm, pud, address); 2041 if (!pmd) 2042 return VM_FAULT_OOM; 2043 pte = pte_alloc_map(mm, pmd, address); 2044 if (!pte) 2045 return VM_FAULT_OOM; 2046 2047 return handle_pte_fault(mm, vma, address, pte, pmd, write_access); 2048} 2049 2050#ifndef __PAGETABLE_PUD_FOLDED 2051/* 2052 * Allocate page upper directory. 2053 * We've already handled the fast-path in-line. 2054 */ 2055int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2056{ 2057 pud_t *new = pud_alloc_one(mm, address); 2058 if (!new) 2059 return -ENOMEM; 2060 2061 spin_lock(&mm->page_table_lock); 2062 if (pgd_present(*pgd)) /* Another has populated it */ 2063 pud_free(new); 2064 else 2065 pgd_populate(mm, pgd, new); 2066 spin_unlock(&mm->page_table_lock); 2067 return 0; 2068} 2069#endif /* __PAGETABLE_PUD_FOLDED */ 2070 2071#ifndef __PAGETABLE_PMD_FOLDED 2072/* 2073 * Allocate page middle directory. 2074 * We've already handled the fast-path in-line. 2075 */ 2076int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2077{ 2078 pmd_t *new = pmd_alloc_one(mm, address); 2079 if (!new) 2080 return -ENOMEM; 2081 2082 spin_lock(&mm->page_table_lock); 2083#ifndef __ARCH_HAS_4LEVEL_HACK 2084 if (pud_present(*pud)) /* Another has populated it */ 2085 pmd_free(new); 2086 else 2087 pud_populate(mm, pud, new); 2088#else 2089 if (pgd_present(*pud)) /* Another has populated it */ 2090 pmd_free(new); 2091 else 2092 pgd_populate(mm, pud, new); 2093#endif /* __ARCH_HAS_4LEVEL_HACK */ 2094 spin_unlock(&mm->page_table_lock); 2095 return 0; 2096} 2097#endif /* __PAGETABLE_PMD_FOLDED */ 2098 2099int make_pages_present(unsigned long addr, unsigned long end) 2100{ 2101 int ret, len, write; 2102 struct vm_area_struct * vma; 2103 2104 vma = find_vma(current->mm, addr); 2105 if (!vma) 2106 return -1; 2107 write = (vma->vm_flags & VM_WRITE) != 0; 2108 if (addr >= end) 2109 BUG(); 2110 if (end > vma->vm_end) 2111 BUG(); 2112 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE; 2113 ret = get_user_pages(current, current->mm, addr, 2114 len, write, 0, NULL, NULL); 2115 if (ret < 0) 2116 return ret; 2117 return ret == len ? 0 : -1; 2118} 2119 2120/* 2121 * Map a vmalloc()-space virtual address to the physical page. 2122 */ 2123struct page * vmalloc_to_page(void * vmalloc_addr) 2124{ 2125 unsigned long addr = (unsigned long) vmalloc_addr; 2126 struct page *page = NULL; 2127 pgd_t *pgd = pgd_offset_k(addr); 2128 pud_t *pud; 2129 pmd_t *pmd; 2130 pte_t *ptep, pte; 2131 2132 if (!pgd_none(*pgd)) { 2133 pud = pud_offset(pgd, addr); 2134 if (!pud_none(*pud)) { 2135 pmd = pmd_offset(pud, addr); 2136 if (!pmd_none(*pmd)) { 2137 ptep = pte_offset_map(pmd, addr); 2138 pte = *ptep; 2139 if (pte_present(pte)) 2140 page = pte_page(pte); 2141 pte_unmap(ptep); 2142 } 2143 } 2144 } 2145 return page; 2146} 2147 2148EXPORT_SYMBOL(vmalloc_to_page); 2149 2150/* 2151 * Map a vmalloc()-space virtual address to the physical page frame number. 2152 */ 2153unsigned long vmalloc_to_pfn(void * vmalloc_addr) 2154{ 2155 return page_to_pfn(vmalloc_to_page(vmalloc_addr)); 2156} 2157 2158EXPORT_SYMBOL(vmalloc_to_pfn); 2159 2160#if !defined(__HAVE_ARCH_GATE_AREA) 2161 2162#if defined(AT_SYSINFO_EHDR) 2163static struct vm_area_struct gate_vma; 2164 2165static int __init gate_vma_init(void) 2166{ 2167 gate_vma.vm_mm = NULL; 2168 gate_vma.vm_start = FIXADDR_USER_START; 2169 gate_vma.vm_end = FIXADDR_USER_END; 2170 gate_vma.vm_page_prot = PAGE_READONLY; 2171 gate_vma.vm_flags = VM_RESERVED; 2172 return 0; 2173} 2174__initcall(gate_vma_init); 2175#endif 2176 2177struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 2178{ 2179#ifdef AT_SYSINFO_EHDR 2180 return &gate_vma; 2181#else 2182 return NULL; 2183#endif 2184} 2185 2186int in_gate_area_no_task(unsigned long addr) 2187{ 2188#ifdef AT_SYSINFO_EHDR 2189 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 2190 return 1; 2191#endif 2192 return 0; 2193} 2194 2195#endif /* __HAVE_ARCH_GATE_AREA */ 2196