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 */ 63 unsigned long max_mapnr; 64 struct page *mem_map; 65 66 EXPORT_SYMBOL(max_mapnr); 67 EXPORT_SYMBOL(mem_map); 68 #endif 69 70 unsigned 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 */ 78 void * high_memory; 79 unsigned long vmalloc_earlyreserve; 80 81 EXPORT_SYMBOL(num_physpages); 82 EXPORT_SYMBOL(high_memory); 83 EXPORT_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 91 void pgd_clear_bad(pgd_t *pgd) 92 { 93 pgd_ERROR(*pgd); 94 pgd_clear(pgd); 95 } 96 97 void pud_clear_bad(pud_t *pud) 98 { 99 pud_ERROR(*pud); 100 pud_clear(pud); 101 } 102 103 void 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 */ 113 static 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 } 122 123 static 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 } 155 156 static 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 */ 194 void 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 } 256 257 void 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 } 291 292 int __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 } 311 312 int __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 } 326 327 static 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 */ 342 void 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 */ 357 358 static inline void 359 copy_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 if (list_empty(&dst_mm->mmlist)) 376 list_add(&dst_mm->mmlist, 377 &src_mm->mmlist); 378 spin_unlock(&mmlist_lock); 379 } 380 } 381 goto out_set_pte; 382 } 383 384 /* If the region is VM_RESERVED, the mapping is not 385 * mapped via rmap - duplicate the pte as is. 386 */ 387 if (vm_flags & VM_RESERVED) 388 goto out_set_pte; 389 390 pfn = pte_pfn(pte); 391 /* If the pte points outside of valid memory but 392 * the region is not VM_RESERVED, we have a problem. 393 */ 394 if (unlikely(!pfn_valid(pfn))) { 395 print_bad_pte(vma, pte, addr); 396 goto out_set_pte; /* try to do something sane */ 397 } 398 399 page = pfn_to_page(pfn); 400 401 /* 402 * If it's a COW mapping, write protect it both 403 * in the parent and the child 404 */ 405 if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) { 406 ptep_set_wrprotect(src_mm, addr, src_pte); 407 pte = *src_pte; 408 } 409 410 /* 411 * If it's a shared mapping, mark it clean in 412 * the child 413 */ 414 if (vm_flags & VM_SHARED) 415 pte = pte_mkclean(pte); 416 pte = pte_mkold(pte); 417 get_page(page); 418 page_dup_rmap(page); 419 rss[!!PageAnon(page)]++; 420 421 out_set_pte: 422 set_pte_at(dst_mm, addr, dst_pte, pte); 423 } 424 425 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 426 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 427 unsigned long addr, unsigned long end) 428 { 429 pte_t *src_pte, *dst_pte; 430 spinlock_t *src_ptl, *dst_ptl; 431 int progress = 0; 432 int rss[2]; 433 434 again: 435 rss[1] = rss[0] = 0; 436 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 437 if (!dst_pte) 438 return -ENOMEM; 439 src_pte = pte_offset_map_nested(src_pmd, addr); 440 src_ptl = pte_lockptr(src_mm, src_pmd); 441 spin_lock(src_ptl); 442 443 do { 444 /* 445 * We are holding two locks at this point - either of them 446 * could generate latencies in another task on another CPU. 447 */ 448 if (progress >= 32) { 449 progress = 0; 450 if (need_resched() || 451 need_lockbreak(src_ptl) || 452 need_lockbreak(dst_ptl)) 453 break; 454 } 455 if (pte_none(*src_pte)) { 456 progress++; 457 continue; 458 } 459 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 460 progress += 8; 461 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 462 463 spin_unlock(src_ptl); 464 pte_unmap_nested(src_pte - 1); 465 add_mm_rss(dst_mm, rss[0], rss[1]); 466 pte_unmap_unlock(dst_pte - 1, dst_ptl); 467 cond_resched(); 468 if (addr != end) 469 goto again; 470 return 0; 471 } 472 473 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 474 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 475 unsigned long addr, unsigned long end) 476 { 477 pmd_t *src_pmd, *dst_pmd; 478 unsigned long next; 479 480 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 481 if (!dst_pmd) 482 return -ENOMEM; 483 src_pmd = pmd_offset(src_pud, addr); 484 do { 485 next = pmd_addr_end(addr, end); 486 if (pmd_none_or_clear_bad(src_pmd)) 487 continue; 488 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 489 vma, addr, next)) 490 return -ENOMEM; 491 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 492 return 0; 493 } 494 495 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 496 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 497 unsigned long addr, unsigned long end) 498 { 499 pud_t *src_pud, *dst_pud; 500 unsigned long next; 501 502 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 503 if (!dst_pud) 504 return -ENOMEM; 505 src_pud = pud_offset(src_pgd, addr); 506 do { 507 next = pud_addr_end(addr, end); 508 if (pud_none_or_clear_bad(src_pud)) 509 continue; 510 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 511 vma, addr, next)) 512 return -ENOMEM; 513 } while (dst_pud++, src_pud++, addr = next, addr != end); 514 return 0; 515 } 516 517 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 518 struct vm_area_struct *vma) 519 { 520 pgd_t *src_pgd, *dst_pgd; 521 unsigned long next; 522 unsigned long addr = vma->vm_start; 523 unsigned long end = vma->vm_end; 524 525 /* 526 * Don't copy ptes where a page fault will fill them correctly. 527 * Fork becomes much lighter when there are big shared or private 528 * readonly mappings. The tradeoff is that copy_page_range is more 529 * efficient than faulting. 530 */ 531 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_RESERVED))) { 532 if (!vma->anon_vma) 533 return 0; 534 } 535 536 if (is_vm_hugetlb_page(vma)) 537 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 538 539 dst_pgd = pgd_offset(dst_mm, addr); 540 src_pgd = pgd_offset(src_mm, addr); 541 do { 542 next = pgd_addr_end(addr, end); 543 if (pgd_none_or_clear_bad(src_pgd)) 544 continue; 545 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 546 vma, addr, next)) 547 return -ENOMEM; 548 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 549 return 0; 550 } 551 552 static void zap_pte_range(struct mmu_gather *tlb, 553 struct vm_area_struct *vma, pmd_t *pmd, 554 unsigned long addr, unsigned long end, 555 struct zap_details *details) 556 { 557 struct mm_struct *mm = tlb->mm; 558 pte_t *pte; 559 spinlock_t *ptl; 560 int file_rss = 0; 561 int anon_rss = 0; 562 563 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 564 do { 565 pte_t ptent = *pte; 566 if (pte_none(ptent)) 567 continue; 568 if (pte_present(ptent)) { 569 struct page *page = NULL; 570 if (!(vma->vm_flags & VM_RESERVED)) { 571 unsigned long pfn = pte_pfn(ptent); 572 if (unlikely(!pfn_valid(pfn))) 573 print_bad_pte(vma, ptent, addr); 574 else 575 page = pfn_to_page(pfn); 576 } 577 if (unlikely(details) && page) { 578 /* 579 * unmap_shared_mapping_pages() wants to 580 * invalidate cache without truncating: 581 * unmap shared but keep private pages. 582 */ 583 if (details->check_mapping && 584 details->check_mapping != page->mapping) 585 continue; 586 /* 587 * Each page->index must be checked when 588 * invalidating or truncating nonlinear. 589 */ 590 if (details->nonlinear_vma && 591 (page->index < details->first_index || 592 page->index > details->last_index)) 593 continue; 594 } 595 ptent = ptep_get_and_clear_full(mm, addr, pte, 596 tlb->fullmm); 597 tlb_remove_tlb_entry(tlb, pte, addr); 598 if (unlikely(!page)) 599 continue; 600 if (unlikely(details) && details->nonlinear_vma 601 && linear_page_index(details->nonlinear_vma, 602 addr) != page->index) 603 set_pte_at(mm, addr, pte, 604 pgoff_to_pte(page->index)); 605 if (PageAnon(page)) 606 anon_rss--; 607 else { 608 if (pte_dirty(ptent)) 609 set_page_dirty(page); 610 if (pte_young(ptent)) 611 mark_page_accessed(page); 612 file_rss--; 613 } 614 page_remove_rmap(page); 615 tlb_remove_page(tlb, page); 616 continue; 617 } 618 /* 619 * If details->check_mapping, we leave swap entries; 620 * if details->nonlinear_vma, we leave file entries. 621 */ 622 if (unlikely(details)) 623 continue; 624 if (!pte_file(ptent)) 625 free_swap_and_cache(pte_to_swp_entry(ptent)); 626 pte_clear_full(mm, addr, pte, tlb->fullmm); 627 } while (pte++, addr += PAGE_SIZE, addr != end); 628 629 add_mm_rss(mm, file_rss, anon_rss); 630 pte_unmap_unlock(pte - 1, ptl); 631 } 632 633 static inline void zap_pmd_range(struct mmu_gather *tlb, 634 struct vm_area_struct *vma, pud_t *pud, 635 unsigned long addr, unsigned long end, 636 struct zap_details *details) 637 { 638 pmd_t *pmd; 639 unsigned long next; 640 641 pmd = pmd_offset(pud, addr); 642 do { 643 next = pmd_addr_end(addr, end); 644 if (pmd_none_or_clear_bad(pmd)) 645 continue; 646 zap_pte_range(tlb, vma, pmd, addr, next, details); 647 } while (pmd++, addr = next, addr != end); 648 } 649 650 static inline void zap_pud_range(struct mmu_gather *tlb, 651 struct vm_area_struct *vma, pgd_t *pgd, 652 unsigned long addr, unsigned long end, 653 struct zap_details *details) 654 { 655 pud_t *pud; 656 unsigned long next; 657 658 pud = pud_offset(pgd, addr); 659 do { 660 next = pud_addr_end(addr, end); 661 if (pud_none_or_clear_bad(pud)) 662 continue; 663 zap_pmd_range(tlb, vma, pud, addr, next, details); 664 } while (pud++, addr = next, addr != end); 665 } 666 667 static void unmap_page_range(struct mmu_gather *tlb, struct vm_area_struct *vma, 668 unsigned long addr, unsigned long end, 669 struct zap_details *details) 670 { 671 pgd_t *pgd; 672 unsigned long next; 673 674 if (details && !details->check_mapping && !details->nonlinear_vma) 675 details = NULL; 676 677 BUG_ON(addr >= end); 678 tlb_start_vma(tlb, vma); 679 pgd = pgd_offset(vma->vm_mm, addr); 680 do { 681 next = pgd_addr_end(addr, end); 682 if (pgd_none_or_clear_bad(pgd)) 683 continue; 684 zap_pud_range(tlb, vma, pgd, addr, next, details); 685 } while (pgd++, addr = next, addr != end); 686 tlb_end_vma(tlb, vma); 687 } 688 689 #ifdef CONFIG_PREEMPT 690 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 691 #else 692 /* No preempt: go for improved straight-line efficiency */ 693 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 694 #endif 695 696 /** 697 * unmap_vmas - unmap a range of memory covered by a list of vma's 698 * @tlbp: address of the caller's struct mmu_gather 699 * @vma: the starting vma 700 * @start_addr: virtual address at which to start unmapping 701 * @end_addr: virtual address at which to end unmapping 702 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 703 * @details: details of nonlinear truncation or shared cache invalidation 704 * 705 * Returns the end address of the unmapping (restart addr if interrupted). 706 * 707 * Unmap all pages in the vma list. 708 * 709 * We aim to not hold locks for too long (for scheduling latency reasons). 710 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 711 * return the ending mmu_gather to the caller. 712 * 713 * Only addresses between `start' and `end' will be unmapped. 714 * 715 * The VMA list must be sorted in ascending virtual address order. 716 * 717 * unmap_vmas() assumes that the caller will flush the whole unmapped address 718 * range after unmap_vmas() returns. So the only responsibility here is to 719 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 720 * drops the lock and schedules. 721 */ 722 unsigned long unmap_vmas(struct mmu_gather **tlbp, 723 struct vm_area_struct *vma, unsigned long start_addr, 724 unsigned long end_addr, unsigned long *nr_accounted, 725 struct zap_details *details) 726 { 727 unsigned long zap_bytes = ZAP_BLOCK_SIZE; 728 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 729 int tlb_start_valid = 0; 730 unsigned long start = start_addr; 731 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 732 int fullmm = (*tlbp)->fullmm; 733 734 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 735 unsigned long end; 736 737 start = max(vma->vm_start, start_addr); 738 if (start >= vma->vm_end) 739 continue; 740 end = min(vma->vm_end, end_addr); 741 if (end <= vma->vm_start) 742 continue; 743 744 if (vma->vm_flags & VM_ACCOUNT) 745 *nr_accounted += (end - start) >> PAGE_SHIFT; 746 747 while (start != end) { 748 unsigned long block; 749 750 if (!tlb_start_valid) { 751 tlb_start = start; 752 tlb_start_valid = 1; 753 } 754 755 if (is_vm_hugetlb_page(vma)) { 756 block = end - start; 757 unmap_hugepage_range(vma, start, end); 758 } else { 759 block = min(zap_bytes, end - start); 760 unmap_page_range(*tlbp, vma, start, 761 start + block, details); 762 } 763 764 start += block; 765 zap_bytes -= block; 766 if ((long)zap_bytes > 0) 767 continue; 768 769 tlb_finish_mmu(*tlbp, tlb_start, start); 770 771 if (need_resched() || 772 (i_mmap_lock && need_lockbreak(i_mmap_lock))) { 773 if (i_mmap_lock) { 774 *tlbp = NULL; 775 goto out; 776 } 777 cond_resched(); 778 } 779 780 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 781 tlb_start_valid = 0; 782 zap_bytes = ZAP_BLOCK_SIZE; 783 } 784 } 785 out: 786 return start; /* which is now the end (or restart) address */ 787 } 788 789 /** 790 * zap_page_range - remove user pages in a given range 791 * @vma: vm_area_struct holding the applicable pages 792 * @address: starting address of pages to zap 793 * @size: number of bytes to zap 794 * @details: details of nonlinear truncation or shared cache invalidation 795 */ 796 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 797 unsigned long size, struct zap_details *details) 798 { 799 struct mm_struct *mm = vma->vm_mm; 800 struct mmu_gather *tlb; 801 unsigned long end = address + size; 802 unsigned long nr_accounted = 0; 803 804 lru_add_drain(); 805 tlb = tlb_gather_mmu(mm, 0); 806 update_hiwater_rss(mm); 807 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 808 if (tlb) 809 tlb_finish_mmu(tlb, address, end); 810 return end; 811 } 812 813 /* 814 * Do a quick page-table lookup for a single page. 815 */ 816 struct page *follow_page(struct mm_struct *mm, unsigned long address, 817 unsigned int flags) 818 { 819 pgd_t *pgd; 820 pud_t *pud; 821 pmd_t *pmd; 822 pte_t *ptep, pte; 823 spinlock_t *ptl; 824 unsigned long pfn; 825 struct page *page; 826 827 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 828 if (!IS_ERR(page)) { 829 BUG_ON(flags & FOLL_GET); 830 goto out; 831 } 832 833 page = NULL; 834 pgd = pgd_offset(mm, address); 835 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 836 goto no_page_table; 837 838 pud = pud_offset(pgd, address); 839 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 840 goto no_page_table; 841 842 pmd = pmd_offset(pud, address); 843 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 844 goto no_page_table; 845 846 if (pmd_huge(*pmd)) { 847 BUG_ON(flags & FOLL_GET); 848 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 849 goto out; 850 } 851 852 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 853 if (!ptep) 854 goto out; 855 856 pte = *ptep; 857 if (!pte_present(pte)) 858 goto unlock; 859 if ((flags & FOLL_WRITE) && !pte_write(pte)) 860 goto unlock; 861 pfn = pte_pfn(pte); 862 if (!pfn_valid(pfn)) 863 goto unlock; 864 865 page = pfn_to_page(pfn); 866 if (flags & FOLL_GET) 867 get_page(page); 868 if (flags & FOLL_TOUCH) { 869 if ((flags & FOLL_WRITE) && 870 !pte_dirty(pte) && !PageDirty(page)) 871 set_page_dirty(page); 872 mark_page_accessed(page); 873 } 874 unlock: 875 pte_unmap_unlock(ptep, ptl); 876 out: 877 return page; 878 879 no_page_table: 880 /* 881 * When core dumping an enormous anonymous area that nobody 882 * has touched so far, we don't want to allocate page tables. 883 */ 884 if (flags & FOLL_ANON) { 885 page = ZERO_PAGE(address); 886 if (flags & FOLL_GET) 887 get_page(page); 888 BUG_ON(flags & FOLL_WRITE); 889 } 890 return page; 891 } 892 893 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 894 unsigned long start, int len, int write, int force, 895 struct page **pages, struct vm_area_struct **vmas) 896 { 897 int i; 898 unsigned int vm_flags; 899 900 /* 901 * Require read or write permissions. 902 * If 'force' is set, we only require the "MAY" flags. 903 */ 904 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 905 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 906 i = 0; 907 908 do { 909 struct vm_area_struct *vma; 910 unsigned int foll_flags; 911 912 vma = find_extend_vma(mm, start); 913 if (!vma && in_gate_area(tsk, start)) { 914 unsigned long pg = start & PAGE_MASK; 915 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 916 pgd_t *pgd; 917 pud_t *pud; 918 pmd_t *pmd; 919 pte_t *pte; 920 if (write) /* user gate pages are read-only */ 921 return i ? : -EFAULT; 922 if (pg > TASK_SIZE) 923 pgd = pgd_offset_k(pg); 924 else 925 pgd = pgd_offset_gate(mm, pg); 926 BUG_ON(pgd_none(*pgd)); 927 pud = pud_offset(pgd, pg); 928 BUG_ON(pud_none(*pud)); 929 pmd = pmd_offset(pud, pg); 930 if (pmd_none(*pmd)) 931 return i ? : -EFAULT; 932 pte = pte_offset_map(pmd, pg); 933 if (pte_none(*pte)) { 934 pte_unmap(pte); 935 return i ? : -EFAULT; 936 } 937 if (pages) { 938 pages[i] = pte_page(*pte); 939 get_page(pages[i]); 940 } 941 pte_unmap(pte); 942 if (vmas) 943 vmas[i] = gate_vma; 944 i++; 945 start += PAGE_SIZE; 946 len--; 947 continue; 948 } 949 950 if (!vma || (vma->vm_flags & (VM_IO | VM_RESERVED)) 951 || !(vm_flags & vma->vm_flags)) 952 return i ? : -EFAULT; 953 954 if (is_vm_hugetlb_page(vma)) { 955 i = follow_hugetlb_page(mm, vma, pages, vmas, 956 &start, &len, i); 957 continue; 958 } 959 960 foll_flags = FOLL_TOUCH; 961 if (pages) 962 foll_flags |= FOLL_GET; 963 if (!write && !(vma->vm_flags & VM_LOCKED) && 964 (!vma->vm_ops || !vma->vm_ops->nopage)) 965 foll_flags |= FOLL_ANON; 966 967 do { 968 struct page *page; 969 970 if (write) 971 foll_flags |= FOLL_WRITE; 972 973 cond_resched(); 974 while (!(page = follow_page(mm, start, foll_flags))) { 975 int ret; 976 ret = __handle_mm_fault(mm, vma, start, 977 foll_flags & FOLL_WRITE); 978 /* 979 * The VM_FAULT_WRITE bit tells us that do_wp_page has 980 * broken COW when necessary, even if maybe_mkwrite 981 * decided not to set pte_write. We can thus safely do 982 * subsequent page lookups as if they were reads. 983 */ 984 if (ret & VM_FAULT_WRITE) 985 foll_flags &= ~FOLL_WRITE; 986 987 switch (ret & ~VM_FAULT_WRITE) { 988 case VM_FAULT_MINOR: 989 tsk->min_flt++; 990 break; 991 case VM_FAULT_MAJOR: 992 tsk->maj_flt++; 993 break; 994 case VM_FAULT_SIGBUS: 995 return i ? i : -EFAULT; 996 case VM_FAULT_OOM: 997 return i ? i : -ENOMEM; 998 default: 999 BUG(); 1000 } 1001 } 1002 if (pages) { 1003 pages[i] = page; 1004 flush_dcache_page(page); 1005 } 1006 if (vmas) 1007 vmas[i] = vma; 1008 i++; 1009 start += PAGE_SIZE; 1010 len--; 1011 } while (len && start < vma->vm_end); 1012 } while (len); 1013 return i; 1014 } 1015 EXPORT_SYMBOL(get_user_pages); 1016 1017 static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1018 unsigned long addr, unsigned long end, pgprot_t prot) 1019 { 1020 pte_t *pte; 1021 spinlock_t *ptl; 1022 1023 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1024 if (!pte) 1025 return -ENOMEM; 1026 do { 1027 struct page *page = ZERO_PAGE(addr); 1028 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot)); 1029 page_cache_get(page); 1030 page_add_file_rmap(page); 1031 inc_mm_counter(mm, file_rss); 1032 BUG_ON(!pte_none(*pte)); 1033 set_pte_at(mm, addr, pte, zero_pte); 1034 } while (pte++, addr += PAGE_SIZE, addr != end); 1035 pte_unmap_unlock(pte - 1, ptl); 1036 return 0; 1037 } 1038 1039 static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud, 1040 unsigned long addr, unsigned long end, pgprot_t prot) 1041 { 1042 pmd_t *pmd; 1043 unsigned long next; 1044 1045 pmd = pmd_alloc(mm, pud, addr); 1046 if (!pmd) 1047 return -ENOMEM; 1048 do { 1049 next = pmd_addr_end(addr, end); 1050 if (zeromap_pte_range(mm, pmd, addr, next, prot)) 1051 return -ENOMEM; 1052 } while (pmd++, addr = next, addr != end); 1053 return 0; 1054 } 1055 1056 static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1057 unsigned long addr, unsigned long end, pgprot_t prot) 1058 { 1059 pud_t *pud; 1060 unsigned long next; 1061 1062 pud = pud_alloc(mm, pgd, addr); 1063 if (!pud) 1064 return -ENOMEM; 1065 do { 1066 next = pud_addr_end(addr, end); 1067 if (zeromap_pmd_range(mm, pud, addr, next, prot)) 1068 return -ENOMEM; 1069 } while (pud++, addr = next, addr != end); 1070 return 0; 1071 } 1072 1073 int zeromap_page_range(struct vm_area_struct *vma, 1074 unsigned long addr, unsigned long size, pgprot_t prot) 1075 { 1076 pgd_t *pgd; 1077 unsigned long next; 1078 unsigned long end = addr + size; 1079 struct mm_struct *mm = vma->vm_mm; 1080 int err; 1081 1082 BUG_ON(addr >= end); 1083 pgd = pgd_offset(mm, addr); 1084 flush_cache_range(vma, addr, end); 1085 do { 1086 next = pgd_addr_end(addr, end); 1087 err = zeromap_pud_range(mm, pgd, addr, next, prot); 1088 if (err) 1089 break; 1090 } while (pgd++, addr = next, addr != end); 1091 return err; 1092 } 1093 1094 /* 1095 * maps a range of physical memory into the requested pages. the old 1096 * mappings are removed. any references to nonexistent pages results 1097 * in null mappings (currently treated as "copy-on-access") 1098 */ 1099 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1100 unsigned long addr, unsigned long end, 1101 unsigned long pfn, pgprot_t prot) 1102 { 1103 pte_t *pte; 1104 spinlock_t *ptl; 1105 1106 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1107 if (!pte) 1108 return -ENOMEM; 1109 do { 1110 BUG_ON(!pte_none(*pte)); 1111 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); 1112 pfn++; 1113 } while (pte++, addr += PAGE_SIZE, addr != end); 1114 pte_unmap_unlock(pte - 1, ptl); 1115 return 0; 1116 } 1117 1118 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1119 unsigned long addr, unsigned long end, 1120 unsigned long pfn, pgprot_t prot) 1121 { 1122 pmd_t *pmd; 1123 unsigned long next; 1124 1125 pfn -= addr >> PAGE_SHIFT; 1126 pmd = pmd_alloc(mm, pud, addr); 1127 if (!pmd) 1128 return -ENOMEM; 1129 do { 1130 next = pmd_addr_end(addr, end); 1131 if (remap_pte_range(mm, pmd, addr, next, 1132 pfn + (addr >> PAGE_SHIFT), prot)) 1133 return -ENOMEM; 1134 } while (pmd++, addr = next, addr != end); 1135 return 0; 1136 } 1137 1138 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1139 unsigned long addr, unsigned long end, 1140 unsigned long pfn, pgprot_t prot) 1141 { 1142 pud_t *pud; 1143 unsigned long next; 1144 1145 pfn -= addr >> PAGE_SHIFT; 1146 pud = pud_alloc(mm, pgd, addr); 1147 if (!pud) 1148 return -ENOMEM; 1149 do { 1150 next = pud_addr_end(addr, end); 1151 if (remap_pmd_range(mm, pud, addr, next, 1152 pfn + (addr >> PAGE_SHIFT), prot)) 1153 return -ENOMEM; 1154 } while (pud++, addr = next, addr != end); 1155 return 0; 1156 } 1157 1158 /* Note: this is only safe if the mm semaphore is held when called. */ 1159 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1160 unsigned long pfn, unsigned long size, pgprot_t prot) 1161 { 1162 pgd_t *pgd; 1163 unsigned long next; 1164 unsigned long end = addr + PAGE_ALIGN(size); 1165 struct mm_struct *mm = vma->vm_mm; 1166 int err; 1167 1168 /* 1169 * Physically remapped pages are special. Tell the 1170 * rest of the world about it: 1171 * VM_IO tells people not to look at these pages 1172 * (accesses can have side effects). 1173 * VM_RESERVED tells the core MM not to "manage" these pages 1174 * (e.g. refcount, mapcount, try to swap them out). 1175 */ 1176 vma->vm_flags |= VM_IO | VM_RESERVED; 1177 1178 BUG_ON(addr >= end); 1179 pfn -= addr >> PAGE_SHIFT; 1180 pgd = pgd_offset(mm, addr); 1181 flush_cache_range(vma, addr, end); 1182 do { 1183 next = pgd_addr_end(addr, end); 1184 err = remap_pud_range(mm, pgd, addr, next, 1185 pfn + (addr >> PAGE_SHIFT), prot); 1186 if (err) 1187 break; 1188 } while (pgd++, addr = next, addr != end); 1189 return err; 1190 } 1191 EXPORT_SYMBOL(remap_pfn_range); 1192 1193 /* 1194 * handle_pte_fault chooses page fault handler according to an entry 1195 * which was read non-atomically. Before making any commitment, on 1196 * those architectures or configurations (e.g. i386 with PAE) which 1197 * might give a mix of unmatched parts, do_swap_page and do_file_page 1198 * must check under lock before unmapping the pte and proceeding 1199 * (but do_wp_page is only called after already making such a check; 1200 * and do_anonymous_page and do_no_page can safely check later on). 1201 */ 1202 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1203 pte_t *page_table, pte_t orig_pte) 1204 { 1205 int same = 1; 1206 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1207 if (sizeof(pte_t) > sizeof(unsigned long)) { 1208 spinlock_t *ptl = pte_lockptr(mm, pmd); 1209 spin_lock(ptl); 1210 same = pte_same(*page_table, orig_pte); 1211 spin_unlock(ptl); 1212 } 1213 #endif 1214 pte_unmap(page_table); 1215 return same; 1216 } 1217 1218 /* 1219 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1220 * servicing faults for write access. In the normal case, do always want 1221 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1222 * that do not have writing enabled, when used by access_process_vm. 1223 */ 1224 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1225 { 1226 if (likely(vma->vm_flags & VM_WRITE)) 1227 pte = pte_mkwrite(pte); 1228 return pte; 1229 } 1230 1231 /* 1232 * This routine handles present pages, when users try to write 1233 * to a shared page. It is done by copying the page to a new address 1234 * and decrementing the shared-page counter for the old page. 1235 * 1236 * Note that this routine assumes that the protection checks have been 1237 * done by the caller (the low-level page fault routine in most cases). 1238 * Thus we can safely just mark it writable once we've done any necessary 1239 * COW. 1240 * 1241 * We also mark the page dirty at this point even though the page will 1242 * change only once the write actually happens. This avoids a few races, 1243 * and potentially makes it more efficient. 1244 * 1245 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1246 * but allow concurrent faults), with pte both mapped and locked. 1247 * We return with mmap_sem still held, but pte unmapped and unlocked. 1248 */ 1249 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1250 unsigned long address, pte_t *page_table, pmd_t *pmd, 1251 spinlock_t *ptl, pte_t orig_pte) 1252 { 1253 struct page *old_page, *new_page; 1254 unsigned long pfn = pte_pfn(orig_pte); 1255 pte_t entry; 1256 int ret = VM_FAULT_MINOR; 1257 1258 BUG_ON(vma->vm_flags & VM_RESERVED); 1259 1260 if (unlikely(!pfn_valid(pfn))) { 1261 /* 1262 * Page table corrupted: show pte and kill process. 1263 */ 1264 print_bad_pte(vma, orig_pte, address); 1265 ret = VM_FAULT_OOM; 1266 goto unlock; 1267 } 1268 old_page = pfn_to_page(pfn); 1269 1270 if (PageAnon(old_page) && !TestSetPageLocked(old_page)) { 1271 int reuse = can_share_swap_page(old_page); 1272 unlock_page(old_page); 1273 if (reuse) { 1274 flush_cache_page(vma, address, pfn); 1275 entry = pte_mkyoung(orig_pte); 1276 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1277 ptep_set_access_flags(vma, address, page_table, entry, 1); 1278 update_mmu_cache(vma, address, entry); 1279 lazy_mmu_prot_update(entry); 1280 ret |= VM_FAULT_WRITE; 1281 goto unlock; 1282 } 1283 } 1284 1285 /* 1286 * Ok, we need to copy. Oh, well.. 1287 */ 1288 page_cache_get(old_page); 1289 pte_unmap_unlock(page_table, ptl); 1290 1291 if (unlikely(anon_vma_prepare(vma))) 1292 goto oom; 1293 if (old_page == ZERO_PAGE(address)) { 1294 new_page = alloc_zeroed_user_highpage(vma, address); 1295 if (!new_page) 1296 goto oom; 1297 } else { 1298 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); 1299 if (!new_page) 1300 goto oom; 1301 copy_user_highpage(new_page, old_page, address); 1302 } 1303 1304 /* 1305 * Re-check the pte - we dropped the lock 1306 */ 1307 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1308 if (likely(pte_same(*page_table, orig_pte))) { 1309 page_remove_rmap(old_page); 1310 if (!PageAnon(old_page)) { 1311 inc_mm_counter(mm, anon_rss); 1312 dec_mm_counter(mm, file_rss); 1313 } 1314 flush_cache_page(vma, address, pfn); 1315 entry = mk_pte(new_page, vma->vm_page_prot); 1316 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1317 ptep_establish(vma, address, page_table, entry); 1318 update_mmu_cache(vma, address, entry); 1319 lazy_mmu_prot_update(entry); 1320 lru_cache_add_active(new_page); 1321 page_add_anon_rmap(new_page, vma, address); 1322 1323 /* Free the old page.. */ 1324 new_page = old_page; 1325 ret |= VM_FAULT_WRITE; 1326 } 1327 page_cache_release(new_page); 1328 page_cache_release(old_page); 1329 unlock: 1330 pte_unmap_unlock(page_table, ptl); 1331 return ret; 1332 oom: 1333 page_cache_release(old_page); 1334 return VM_FAULT_OOM; 1335 } 1336 1337 /* 1338 * Helper functions for unmap_mapping_range(). 1339 * 1340 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 1341 * 1342 * We have to restart searching the prio_tree whenever we drop the lock, 1343 * since the iterator is only valid while the lock is held, and anyway 1344 * a later vma might be split and reinserted earlier while lock dropped. 1345 * 1346 * The list of nonlinear vmas could be handled more efficiently, using 1347 * a placeholder, but handle it in the same way until a need is shown. 1348 * It is important to search the prio_tree before nonlinear list: a vma 1349 * may become nonlinear and be shifted from prio_tree to nonlinear list 1350 * while the lock is dropped; but never shifted from list to prio_tree. 1351 * 1352 * In order to make forward progress despite restarting the search, 1353 * vm_truncate_count is used to mark a vma as now dealt with, so we can 1354 * quickly skip it next time around. Since the prio_tree search only 1355 * shows us those vmas affected by unmapping the range in question, we 1356 * can't efficiently keep all vmas in step with mapping->truncate_count: 1357 * so instead reset them all whenever it wraps back to 0 (then go to 1). 1358 * mapping->truncate_count and vma->vm_truncate_count are protected by 1359 * i_mmap_lock. 1360 * 1361 * In order to make forward progress despite repeatedly restarting some 1362 * large vma, note the restart_addr from unmap_vmas when it breaks out: 1363 * and restart from that address when we reach that vma again. It might 1364 * have been split or merged, shrunk or extended, but never shifted: so 1365 * restart_addr remains valid so long as it remains in the vma's range. 1366 * unmap_mapping_range forces truncate_count to leap over page-aligned 1367 * values so we can save vma's restart_addr in its truncate_count field. 1368 */ 1369 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 1370 1371 static void reset_vma_truncate_counts(struct address_space *mapping) 1372 { 1373 struct vm_area_struct *vma; 1374 struct prio_tree_iter iter; 1375 1376 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 1377 vma->vm_truncate_count = 0; 1378 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 1379 vma->vm_truncate_count = 0; 1380 } 1381 1382 static int unmap_mapping_range_vma(struct vm_area_struct *vma, 1383 unsigned long start_addr, unsigned long end_addr, 1384 struct zap_details *details) 1385 { 1386 unsigned long restart_addr; 1387 int need_break; 1388 1389 again: 1390 restart_addr = vma->vm_truncate_count; 1391 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 1392 start_addr = restart_addr; 1393 if (start_addr >= end_addr) { 1394 /* Top of vma has been split off since last time */ 1395 vma->vm_truncate_count = details->truncate_count; 1396 return 0; 1397 } 1398 } 1399 1400 restart_addr = zap_page_range(vma, start_addr, 1401 end_addr - start_addr, details); 1402 need_break = need_resched() || 1403 need_lockbreak(details->i_mmap_lock); 1404 1405 if (restart_addr >= end_addr) { 1406 /* We have now completed this vma: mark it so */ 1407 vma->vm_truncate_count = details->truncate_count; 1408 if (!need_break) 1409 return 0; 1410 } else { 1411 /* Note restart_addr in vma's truncate_count field */ 1412 vma->vm_truncate_count = restart_addr; 1413 if (!need_break) 1414 goto again; 1415 } 1416 1417 spin_unlock(details->i_mmap_lock); 1418 cond_resched(); 1419 spin_lock(details->i_mmap_lock); 1420 return -EINTR; 1421 } 1422 1423 static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 1424 struct zap_details *details) 1425 { 1426 struct vm_area_struct *vma; 1427 struct prio_tree_iter iter; 1428 pgoff_t vba, vea, zba, zea; 1429 1430 restart: 1431 vma_prio_tree_foreach(vma, &iter, root, 1432 details->first_index, details->last_index) { 1433 /* Skip quickly over those we have already dealt with */ 1434 if (vma->vm_truncate_count == details->truncate_count) 1435 continue; 1436 1437 vba = vma->vm_pgoff; 1438 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 1439 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 1440 zba = details->first_index; 1441 if (zba < vba) 1442 zba = vba; 1443 zea = details->last_index; 1444 if (zea > vea) 1445 zea = vea; 1446 1447 if (unmap_mapping_range_vma(vma, 1448 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 1449 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 1450 details) < 0) 1451 goto restart; 1452 } 1453 } 1454 1455 static inline void unmap_mapping_range_list(struct list_head *head, 1456 struct zap_details *details) 1457 { 1458 struct vm_area_struct *vma; 1459 1460 /* 1461 * In nonlinear VMAs there is no correspondence between virtual address 1462 * offset and file offset. So we must perform an exhaustive search 1463 * across *all* the pages in each nonlinear VMA, not just the pages 1464 * whose virtual address lies outside the file truncation point. 1465 */ 1466 restart: 1467 list_for_each_entry(vma, head, shared.vm_set.list) { 1468 /* Skip quickly over those we have already dealt with */ 1469 if (vma->vm_truncate_count == details->truncate_count) 1470 continue; 1471 details->nonlinear_vma = vma; 1472 if (unmap_mapping_range_vma(vma, vma->vm_start, 1473 vma->vm_end, details) < 0) 1474 goto restart; 1475 } 1476 } 1477 1478 /** 1479 * unmap_mapping_range - unmap the portion of all mmaps 1480 * in the specified address_space corresponding to the specified 1481 * page range in the underlying file. 1482 * @mapping: the address space containing mmaps to be unmapped. 1483 * @holebegin: byte in first page to unmap, relative to the start of 1484 * the underlying file. This will be rounded down to a PAGE_SIZE 1485 * boundary. Note that this is different from vmtruncate(), which 1486 * must keep the partial page. In contrast, we must get rid of 1487 * partial pages. 1488 * @holelen: size of prospective hole in bytes. This will be rounded 1489 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 1490 * end of the file. 1491 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 1492 * but 0 when invalidating pagecache, don't throw away private data. 1493 */ 1494 void unmap_mapping_range(struct address_space *mapping, 1495 loff_t const holebegin, loff_t const holelen, int even_cows) 1496 { 1497 struct zap_details details; 1498 pgoff_t hba = holebegin >> PAGE_SHIFT; 1499 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1500 1501 /* Check for overflow. */ 1502 if (sizeof(holelen) > sizeof(hlen)) { 1503 long long holeend = 1504 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1505 if (holeend & ~(long long)ULONG_MAX) 1506 hlen = ULONG_MAX - hba + 1; 1507 } 1508 1509 details.check_mapping = even_cows? NULL: mapping; 1510 details.nonlinear_vma = NULL; 1511 details.first_index = hba; 1512 details.last_index = hba + hlen - 1; 1513 if (details.last_index < details.first_index) 1514 details.last_index = ULONG_MAX; 1515 details.i_mmap_lock = &mapping->i_mmap_lock; 1516 1517 spin_lock(&mapping->i_mmap_lock); 1518 1519 /* serialize i_size write against truncate_count write */ 1520 smp_wmb(); 1521 /* Protect against page faults, and endless unmapping loops */ 1522 mapping->truncate_count++; 1523 /* 1524 * For archs where spin_lock has inclusive semantics like ia64 1525 * this smp_mb() will prevent to read pagetable contents 1526 * before the truncate_count increment is visible to 1527 * other cpus. 1528 */ 1529 smp_mb(); 1530 if (unlikely(is_restart_addr(mapping->truncate_count))) { 1531 if (mapping->truncate_count == 0) 1532 reset_vma_truncate_counts(mapping); 1533 mapping->truncate_count++; 1534 } 1535 details.truncate_count = mapping->truncate_count; 1536 1537 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 1538 unmap_mapping_range_tree(&mapping->i_mmap, &details); 1539 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 1540 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 1541 spin_unlock(&mapping->i_mmap_lock); 1542 } 1543 EXPORT_SYMBOL(unmap_mapping_range); 1544 1545 /* 1546 * Handle all mappings that got truncated by a "truncate()" 1547 * system call. 1548 * 1549 * NOTE! We have to be ready to update the memory sharing 1550 * between the file and the memory map for a potential last 1551 * incomplete page. Ugly, but necessary. 1552 */ 1553 int vmtruncate(struct inode * inode, loff_t offset) 1554 { 1555 struct address_space *mapping = inode->i_mapping; 1556 unsigned long limit; 1557 1558 if (inode->i_size < offset) 1559 goto do_expand; 1560 /* 1561 * truncation of in-use swapfiles is disallowed - it would cause 1562 * subsequent swapout to scribble on the now-freed blocks. 1563 */ 1564 if (IS_SWAPFILE(inode)) 1565 goto out_busy; 1566 i_size_write(inode, offset); 1567 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1568 truncate_inode_pages(mapping, offset); 1569 goto out_truncate; 1570 1571 do_expand: 1572 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1573 if (limit != RLIM_INFINITY && offset > limit) 1574 goto out_sig; 1575 if (offset > inode->i_sb->s_maxbytes) 1576 goto out_big; 1577 i_size_write(inode, offset); 1578 1579 out_truncate: 1580 if (inode->i_op && inode->i_op->truncate) 1581 inode->i_op->truncate(inode); 1582 return 0; 1583 out_sig: 1584 send_sig(SIGXFSZ, current, 0); 1585 out_big: 1586 return -EFBIG; 1587 out_busy: 1588 return -ETXTBSY; 1589 } 1590 1591 EXPORT_SYMBOL(vmtruncate); 1592 1593 /* 1594 * Primitive swap readahead code. We simply read an aligned block of 1595 * (1 << page_cluster) entries in the swap area. This method is chosen 1596 * because it doesn't cost us any seek time. We also make sure to queue 1597 * the 'original' request together with the readahead ones... 1598 * 1599 * This has been extended to use the NUMA policies from the mm triggering 1600 * the readahead. 1601 * 1602 * Caller must hold down_read on the vma->vm_mm if vma is not NULL. 1603 */ 1604 void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) 1605 { 1606 #ifdef CONFIG_NUMA 1607 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; 1608 #endif 1609 int i, num; 1610 struct page *new_page; 1611 unsigned long offset; 1612 1613 /* 1614 * Get the number of handles we should do readahead io to. 1615 */ 1616 num = valid_swaphandles(entry, &offset); 1617 for (i = 0; i < num; offset++, i++) { 1618 /* Ok, do the async read-ahead now */ 1619 new_page = read_swap_cache_async(swp_entry(swp_type(entry), 1620 offset), vma, addr); 1621 if (!new_page) 1622 break; 1623 page_cache_release(new_page); 1624 #ifdef CONFIG_NUMA 1625 /* 1626 * Find the next applicable VMA for the NUMA policy. 1627 */ 1628 addr += PAGE_SIZE; 1629 if (addr == 0) 1630 vma = NULL; 1631 if (vma) { 1632 if (addr >= vma->vm_end) { 1633 vma = next_vma; 1634 next_vma = vma ? vma->vm_next : NULL; 1635 } 1636 if (vma && addr < vma->vm_start) 1637 vma = NULL; 1638 } else { 1639 if (next_vma && addr >= next_vma->vm_start) { 1640 vma = next_vma; 1641 next_vma = vma->vm_next; 1642 } 1643 } 1644 #endif 1645 } 1646 lru_add_drain(); /* Push any new pages onto the LRU now */ 1647 } 1648 1649 /* 1650 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1651 * but allow concurrent faults), and pte mapped but not yet locked. 1652 * We return with mmap_sem still held, but pte unmapped and unlocked. 1653 */ 1654 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 1655 unsigned long address, pte_t *page_table, pmd_t *pmd, 1656 int write_access, pte_t orig_pte) 1657 { 1658 spinlock_t *ptl; 1659 struct page *page; 1660 swp_entry_t entry; 1661 pte_t pte; 1662 int ret = VM_FAULT_MINOR; 1663 1664 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 1665 goto out; 1666 1667 entry = pte_to_swp_entry(orig_pte); 1668 page = lookup_swap_cache(entry); 1669 if (!page) { 1670 swapin_readahead(entry, address, vma); 1671 page = read_swap_cache_async(entry, vma, address); 1672 if (!page) { 1673 /* 1674 * Back out if somebody else faulted in this pte 1675 * while we released the pte lock. 1676 */ 1677 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1678 if (likely(pte_same(*page_table, orig_pte))) 1679 ret = VM_FAULT_OOM; 1680 goto unlock; 1681 } 1682 1683 /* Had to read the page from swap area: Major fault */ 1684 ret = VM_FAULT_MAJOR; 1685 inc_page_state(pgmajfault); 1686 grab_swap_token(); 1687 } 1688 1689 mark_page_accessed(page); 1690 lock_page(page); 1691 1692 /* 1693 * Back out if somebody else already faulted in this pte. 1694 */ 1695 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1696 if (unlikely(!pte_same(*page_table, orig_pte))) 1697 goto out_nomap; 1698 1699 if (unlikely(!PageUptodate(page))) { 1700 ret = VM_FAULT_SIGBUS; 1701 goto out_nomap; 1702 } 1703 1704 /* The page isn't present yet, go ahead with the fault. */ 1705 1706 inc_mm_counter(mm, anon_rss); 1707 pte = mk_pte(page, vma->vm_page_prot); 1708 if (write_access && can_share_swap_page(page)) { 1709 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 1710 write_access = 0; 1711 } 1712 1713 flush_icache_page(vma, page); 1714 set_pte_at(mm, address, page_table, pte); 1715 page_add_anon_rmap(page, vma, address); 1716 1717 swap_free(entry); 1718 if (vm_swap_full()) 1719 remove_exclusive_swap_page(page); 1720 unlock_page(page); 1721 1722 if (write_access) { 1723 if (do_wp_page(mm, vma, address, 1724 page_table, pmd, ptl, pte) == VM_FAULT_OOM) 1725 ret = VM_FAULT_OOM; 1726 goto out; 1727 } 1728 1729 /* No need to invalidate - it was non-present before */ 1730 update_mmu_cache(vma, address, pte); 1731 lazy_mmu_prot_update(pte); 1732 unlock: 1733 pte_unmap_unlock(page_table, ptl); 1734 out: 1735 return ret; 1736 out_nomap: 1737 pte_unmap_unlock(page_table, ptl); 1738 unlock_page(page); 1739 page_cache_release(page); 1740 return ret; 1741 } 1742 1743 /* 1744 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1745 * but allow concurrent faults), and pte mapped but not yet locked. 1746 * We return with mmap_sem still held, but pte unmapped and unlocked. 1747 */ 1748 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 1749 unsigned long address, pte_t *page_table, pmd_t *pmd, 1750 int write_access) 1751 { 1752 struct page *page; 1753 spinlock_t *ptl; 1754 pte_t entry; 1755 1756 if (write_access) { 1757 /* Allocate our own private page. */ 1758 pte_unmap(page_table); 1759 1760 if (unlikely(anon_vma_prepare(vma))) 1761 goto oom; 1762 page = alloc_zeroed_user_highpage(vma, address); 1763 if (!page) 1764 goto oom; 1765 1766 entry = mk_pte(page, vma->vm_page_prot); 1767 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1768 1769 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1770 if (!pte_none(*page_table)) 1771 goto release; 1772 inc_mm_counter(mm, anon_rss); 1773 lru_cache_add_active(page); 1774 SetPageReferenced(page); 1775 page_add_anon_rmap(page, vma, address); 1776 } else { 1777 /* Map the ZERO_PAGE - vm_page_prot is readonly */ 1778 page = ZERO_PAGE(address); 1779 page_cache_get(page); 1780 entry = mk_pte(page, vma->vm_page_prot); 1781 1782 ptl = pte_lockptr(mm, pmd); 1783 spin_lock(ptl); 1784 if (!pte_none(*page_table)) 1785 goto release; 1786 inc_mm_counter(mm, file_rss); 1787 page_add_file_rmap(page); 1788 } 1789 1790 set_pte_at(mm, address, page_table, entry); 1791 1792 /* No need to invalidate - it was non-present before */ 1793 update_mmu_cache(vma, address, entry); 1794 lazy_mmu_prot_update(entry); 1795 unlock: 1796 pte_unmap_unlock(page_table, ptl); 1797 return VM_FAULT_MINOR; 1798 release: 1799 page_cache_release(page); 1800 goto unlock; 1801 oom: 1802 return VM_FAULT_OOM; 1803 } 1804 1805 /* 1806 * do_no_page() tries to create a new page mapping. It aggressively 1807 * tries to share with existing pages, but makes a separate copy if 1808 * the "write_access" parameter is true in order to avoid the next 1809 * page fault. 1810 * 1811 * As this is called only for pages that do not currently exist, we 1812 * do not need to flush old virtual caches or the TLB. 1813 * 1814 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1815 * but allow concurrent faults), and pte mapped but not yet locked. 1816 * We return with mmap_sem still held, but pte unmapped and unlocked. 1817 */ 1818 static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 1819 unsigned long address, pte_t *page_table, pmd_t *pmd, 1820 int write_access) 1821 { 1822 spinlock_t *ptl; 1823 struct page *new_page; 1824 struct address_space *mapping = NULL; 1825 pte_t entry; 1826 unsigned int sequence = 0; 1827 int ret = VM_FAULT_MINOR; 1828 int anon = 0; 1829 1830 pte_unmap(page_table); 1831 1832 if (vma->vm_file) { 1833 mapping = vma->vm_file->f_mapping; 1834 sequence = mapping->truncate_count; 1835 smp_rmb(); /* serializes i_size against truncate_count */ 1836 } 1837 retry: 1838 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); 1839 /* 1840 * No smp_rmb is needed here as long as there's a full 1841 * spin_lock/unlock sequence inside the ->nopage callback 1842 * (for the pagecache lookup) that acts as an implicit 1843 * smp_mb() and prevents the i_size read to happen 1844 * after the next truncate_count read. 1845 */ 1846 1847 /* no page was available -- either SIGBUS or OOM */ 1848 if (new_page == NOPAGE_SIGBUS) 1849 return VM_FAULT_SIGBUS; 1850 if (new_page == NOPAGE_OOM) 1851 return VM_FAULT_OOM; 1852 1853 /* 1854 * Should we do an early C-O-W break? 1855 */ 1856 if (write_access && !(vma->vm_flags & VM_SHARED)) { 1857 struct page *page; 1858 1859 if (unlikely(anon_vma_prepare(vma))) 1860 goto oom; 1861 page = alloc_page_vma(GFP_HIGHUSER, vma, address); 1862 if (!page) 1863 goto oom; 1864 copy_user_highpage(page, new_page, address); 1865 page_cache_release(new_page); 1866 new_page = page; 1867 anon = 1; 1868 } 1869 1870 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1871 /* 1872 * For a file-backed vma, someone could have truncated or otherwise 1873 * invalidated this page. If unmap_mapping_range got called, 1874 * retry getting the page. 1875 */ 1876 if (mapping && unlikely(sequence != mapping->truncate_count)) { 1877 pte_unmap_unlock(page_table, ptl); 1878 page_cache_release(new_page); 1879 cond_resched(); 1880 sequence = mapping->truncate_count; 1881 smp_rmb(); 1882 goto retry; 1883 } 1884 1885 /* 1886 * This silly early PAGE_DIRTY setting removes a race 1887 * due to the bad i386 page protection. But it's valid 1888 * for other architectures too. 1889 * 1890 * Note that if write_access is true, we either now have 1891 * an exclusive copy of the page, or this is a shared mapping, 1892 * so we can make it writable and dirty to avoid having to 1893 * handle that later. 1894 */ 1895 /* Only go through if we didn't race with anybody else... */ 1896 if (pte_none(*page_table)) { 1897 flush_icache_page(vma, new_page); 1898 entry = mk_pte(new_page, vma->vm_page_prot); 1899 if (write_access) 1900 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1901 set_pte_at(mm, address, page_table, entry); 1902 if (anon) { 1903 inc_mm_counter(mm, anon_rss); 1904 lru_cache_add_active(new_page); 1905 page_add_anon_rmap(new_page, vma, address); 1906 } else if (!(vma->vm_flags & VM_RESERVED)) { 1907 inc_mm_counter(mm, file_rss); 1908 page_add_file_rmap(new_page); 1909 } 1910 } else { 1911 /* One of our sibling threads was faster, back out. */ 1912 page_cache_release(new_page); 1913 goto unlock; 1914 } 1915 1916 /* no need to invalidate: a not-present page shouldn't be cached */ 1917 update_mmu_cache(vma, address, entry); 1918 lazy_mmu_prot_update(entry); 1919 unlock: 1920 pte_unmap_unlock(page_table, ptl); 1921 return ret; 1922 oom: 1923 page_cache_release(new_page); 1924 return VM_FAULT_OOM; 1925 } 1926 1927 /* 1928 * Fault of a previously existing named mapping. Repopulate the pte 1929 * from the encoded file_pte if possible. This enables swappable 1930 * nonlinear vmas. 1931 * 1932 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1933 * but allow concurrent faults), and pte mapped but not yet locked. 1934 * We return with mmap_sem still held, but pte unmapped and unlocked. 1935 */ 1936 static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma, 1937 unsigned long address, pte_t *page_table, pmd_t *pmd, 1938 int write_access, pte_t orig_pte) 1939 { 1940 pgoff_t pgoff; 1941 int err; 1942 1943 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 1944 return VM_FAULT_MINOR; 1945 1946 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 1947 /* 1948 * Page table corrupted: show pte and kill process. 1949 */ 1950 print_bad_pte(vma, orig_pte, address); 1951 return VM_FAULT_OOM; 1952 } 1953 /* We can then assume vm->vm_ops && vma->vm_ops->populate */ 1954 1955 pgoff = pte_to_pgoff(orig_pte); 1956 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, 1957 vma->vm_page_prot, pgoff, 0); 1958 if (err == -ENOMEM) 1959 return VM_FAULT_OOM; 1960 if (err) 1961 return VM_FAULT_SIGBUS; 1962 return VM_FAULT_MAJOR; 1963 } 1964 1965 /* 1966 * These routines also need to handle stuff like marking pages dirty 1967 * and/or accessed for architectures that don't do it in hardware (most 1968 * RISC architectures). The early dirtying is also good on the i386. 1969 * 1970 * There is also a hook called "update_mmu_cache()" that architectures 1971 * with external mmu caches can use to update those (ie the Sparc or 1972 * PowerPC hashed page tables that act as extended TLBs). 1973 * 1974 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1975 * but allow concurrent faults), and pte mapped but not yet locked. 1976 * We return with mmap_sem still held, but pte unmapped and unlocked. 1977 */ 1978 static inline int handle_pte_fault(struct mm_struct *mm, 1979 struct vm_area_struct *vma, unsigned long address, 1980 pte_t *pte, pmd_t *pmd, int write_access) 1981 { 1982 pte_t entry; 1983 pte_t old_entry; 1984 spinlock_t *ptl; 1985 1986 old_entry = entry = *pte; 1987 if (!pte_present(entry)) { 1988 if (pte_none(entry)) { 1989 if (!vma->vm_ops || !vma->vm_ops->nopage) 1990 return do_anonymous_page(mm, vma, address, 1991 pte, pmd, write_access); 1992 return do_no_page(mm, vma, address, 1993 pte, pmd, write_access); 1994 } 1995 if (pte_file(entry)) 1996 return do_file_page(mm, vma, address, 1997 pte, pmd, write_access, entry); 1998 return do_swap_page(mm, vma, address, 1999 pte, pmd, write_access, entry); 2000 } 2001 2002 ptl = pte_lockptr(mm, pmd); 2003 spin_lock(ptl); 2004 if (unlikely(!pte_same(*pte, entry))) 2005 goto unlock; 2006 if (write_access) { 2007 if (!pte_write(entry)) 2008 return do_wp_page(mm, vma, address, 2009 pte, pmd, ptl, entry); 2010 entry = pte_mkdirty(entry); 2011 } 2012 entry = pte_mkyoung(entry); 2013 if (!pte_same(old_entry, entry)) { 2014 ptep_set_access_flags(vma, address, pte, entry, write_access); 2015 update_mmu_cache(vma, address, entry); 2016 lazy_mmu_prot_update(entry); 2017 } else { 2018 /* 2019 * This is needed only for protection faults but the arch code 2020 * is not yet telling us if this is a protection fault or not. 2021 * This still avoids useless tlb flushes for .text page faults 2022 * with threads. 2023 */ 2024 if (write_access) 2025 flush_tlb_page(vma, address); 2026 } 2027 unlock: 2028 pte_unmap_unlock(pte, ptl); 2029 return VM_FAULT_MINOR; 2030 } 2031 2032 /* 2033 * By the time we get here, we already hold the mm semaphore 2034 */ 2035 int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2036 unsigned long address, int write_access) 2037 { 2038 pgd_t *pgd; 2039 pud_t *pud; 2040 pmd_t *pmd; 2041 pte_t *pte; 2042 2043 __set_current_state(TASK_RUNNING); 2044 2045 inc_page_state(pgfault); 2046 2047 if (unlikely(is_vm_hugetlb_page(vma))) 2048 return hugetlb_fault(mm, vma, address, write_access); 2049 2050 pgd = pgd_offset(mm, address); 2051 pud = pud_alloc(mm, pgd, address); 2052 if (!pud) 2053 return VM_FAULT_OOM; 2054 pmd = pmd_alloc(mm, pud, address); 2055 if (!pmd) 2056 return VM_FAULT_OOM; 2057 pte = pte_alloc_map(mm, pmd, address); 2058 if (!pte) 2059 return VM_FAULT_OOM; 2060 2061 return handle_pte_fault(mm, vma, address, pte, pmd, write_access); 2062 } 2063 2064 #ifndef __PAGETABLE_PUD_FOLDED 2065 /* 2066 * Allocate page upper directory. 2067 * We've already handled the fast-path in-line. 2068 */ 2069 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2070 { 2071 pud_t *new = pud_alloc_one(mm, address); 2072 if (!new) 2073 return -ENOMEM; 2074 2075 spin_lock(&mm->page_table_lock); 2076 if (pgd_present(*pgd)) /* Another has populated it */ 2077 pud_free(new); 2078 else 2079 pgd_populate(mm, pgd, new); 2080 spin_unlock(&mm->page_table_lock); 2081 return 0; 2082 } 2083 #endif /* __PAGETABLE_PUD_FOLDED */ 2084 2085 #ifndef __PAGETABLE_PMD_FOLDED 2086 /* 2087 * Allocate page middle directory. 2088 * We've already handled the fast-path in-line. 2089 */ 2090 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2091 { 2092 pmd_t *new = pmd_alloc_one(mm, address); 2093 if (!new) 2094 return -ENOMEM; 2095 2096 spin_lock(&mm->page_table_lock); 2097 #ifndef __ARCH_HAS_4LEVEL_HACK 2098 if (pud_present(*pud)) /* Another has populated it */ 2099 pmd_free(new); 2100 else 2101 pud_populate(mm, pud, new); 2102 #else 2103 if (pgd_present(*pud)) /* Another has populated it */ 2104 pmd_free(new); 2105 else 2106 pgd_populate(mm, pud, new); 2107 #endif /* __ARCH_HAS_4LEVEL_HACK */ 2108 spin_unlock(&mm->page_table_lock); 2109 return 0; 2110 } 2111 #endif /* __PAGETABLE_PMD_FOLDED */ 2112 2113 int make_pages_present(unsigned long addr, unsigned long end) 2114 { 2115 int ret, len, write; 2116 struct vm_area_struct * vma; 2117 2118 vma = find_vma(current->mm, addr); 2119 if (!vma) 2120 return -1; 2121 write = (vma->vm_flags & VM_WRITE) != 0; 2122 if (addr >= end) 2123 BUG(); 2124 if (end > vma->vm_end) 2125 BUG(); 2126 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE; 2127 ret = get_user_pages(current, current->mm, addr, 2128 len, write, 0, NULL, NULL); 2129 if (ret < 0) 2130 return ret; 2131 return ret == len ? 0 : -1; 2132 } 2133 2134 /* 2135 * Map a vmalloc()-space virtual address to the physical page. 2136 */ 2137 struct page * vmalloc_to_page(void * vmalloc_addr) 2138 { 2139 unsigned long addr = (unsigned long) vmalloc_addr; 2140 struct page *page = NULL; 2141 pgd_t *pgd = pgd_offset_k(addr); 2142 pud_t *pud; 2143 pmd_t *pmd; 2144 pte_t *ptep, pte; 2145 2146 if (!pgd_none(*pgd)) { 2147 pud = pud_offset(pgd, addr); 2148 if (!pud_none(*pud)) { 2149 pmd = pmd_offset(pud, addr); 2150 if (!pmd_none(*pmd)) { 2151 ptep = pte_offset_map(pmd, addr); 2152 pte = *ptep; 2153 if (pte_present(pte)) 2154 page = pte_page(pte); 2155 pte_unmap(ptep); 2156 } 2157 } 2158 } 2159 return page; 2160 } 2161 2162 EXPORT_SYMBOL(vmalloc_to_page); 2163 2164 /* 2165 * Map a vmalloc()-space virtual address to the physical page frame number. 2166 */ 2167 unsigned long vmalloc_to_pfn(void * vmalloc_addr) 2168 { 2169 return page_to_pfn(vmalloc_to_page(vmalloc_addr)); 2170 } 2171 2172 EXPORT_SYMBOL(vmalloc_to_pfn); 2173 2174 #if !defined(__HAVE_ARCH_GATE_AREA) 2175 2176 #if defined(AT_SYSINFO_EHDR) 2177 static struct vm_area_struct gate_vma; 2178 2179 static int __init gate_vma_init(void) 2180 { 2181 gate_vma.vm_mm = NULL; 2182 gate_vma.vm_start = FIXADDR_USER_START; 2183 gate_vma.vm_end = FIXADDR_USER_END; 2184 gate_vma.vm_page_prot = PAGE_READONLY; 2185 gate_vma.vm_flags = VM_RESERVED; 2186 return 0; 2187 } 2188 __initcall(gate_vma_init); 2189 #endif 2190 2191 struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 2192 { 2193 #ifdef AT_SYSINFO_EHDR 2194 return &gate_vma; 2195 #else 2196 return NULL; 2197 #endif 2198 } 2199 2200 int in_gate_area_no_task(unsigned long addr) 2201 { 2202 #ifdef AT_SYSINFO_EHDR 2203 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 2204 return 1; 2205 #endif 2206 return 0; 2207 } 2208 2209 #endif /* __HAVE_ARCH_GATE_AREA */ 2210