memory.c revision 5d2a2dbbc1025dbf7998b9289574d9592b8f21cc
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 bad pte 337 * is found. For example, we might have a PFN-mapped pte in 338 * a region that doesn't allow it. 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 * This function gets the "struct page" associated with a pte. 354 * 355 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping 356 * will have each page table entry just pointing to a raw page frame 357 * number, and as far as the VM layer is concerned, those do not have 358 * pages associated with them - even if the PFN might point to memory 359 * that otherwise is perfectly fine and has a "struct page". 360 * 361 * The way we recognize those mappings is through the rules set up 362 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set, 363 * and the vm_pgoff will point to the first PFN mapped: thus every 364 * page that is a raw mapping will always honor the rule 365 * 366 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 367 * 368 * and if that isn't true, the page has been COW'ed (in which case it 369 * _does_ have a "struct page" associated with it even if it is in a 370 * VM_PFNMAP range). 371 */ 372struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte) 373{ 374 unsigned long pfn = pte_pfn(pte); 375 376 if (vma->vm_flags & VM_PFNMAP) { 377 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT; 378 if (pfn == vma->vm_pgoff + off) 379 return NULL; 380 } 381 382 /* 383 * Add some anal sanity checks for now. Eventually, 384 * we should just do "return pfn_to_page(pfn)", but 385 * in the meantime we check that we get a valid pfn, 386 * and that the resulting page looks ok. 387 * 388 * Remove this test eventually! 389 */ 390 if (unlikely(!pfn_valid(pfn))) { 391 print_bad_pte(vma, pte, addr); 392 return NULL; 393 } 394 395 /* 396 * NOTE! We still have PageReserved() pages in the page 397 * tables. 398 * 399 * The PAGE_ZERO() pages and various VDSO mappings can 400 * cause them to exist. 401 */ 402 return pfn_to_page(pfn); 403} 404 405/* 406 * copy one vm_area from one task to the other. Assumes the page tables 407 * already present in the new task to be cleared in the whole range 408 * covered by this vma. 409 */ 410 411static inline void 412copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 413 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 414 unsigned long addr, int *rss) 415{ 416 unsigned long vm_flags = vma->vm_flags; 417 pte_t pte = *src_pte; 418 struct page *page; 419 420 /* pte contains position in swap or file, so copy. */ 421 if (unlikely(!pte_present(pte))) { 422 if (!pte_file(pte)) { 423 swap_duplicate(pte_to_swp_entry(pte)); 424 /* make sure dst_mm is on swapoff's mmlist. */ 425 if (unlikely(list_empty(&dst_mm->mmlist))) { 426 spin_lock(&mmlist_lock); 427 if (list_empty(&dst_mm->mmlist)) 428 list_add(&dst_mm->mmlist, 429 &src_mm->mmlist); 430 spin_unlock(&mmlist_lock); 431 } 432 } 433 goto out_set_pte; 434 } 435 436 /* 437 * If it's a COW mapping, write protect it both 438 * in the parent and the child 439 */ 440 if ((vm_flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE) { 441 ptep_set_wrprotect(src_mm, addr, src_pte); 442 pte = *src_pte; 443 } 444 445 /* 446 * If it's a shared mapping, mark it clean in 447 * the child 448 */ 449 if (vm_flags & VM_SHARED) 450 pte = pte_mkclean(pte); 451 pte = pte_mkold(pte); 452 453 page = vm_normal_page(vma, addr, pte); 454 if (page) { 455 get_page(page); 456 page_dup_rmap(page); 457 rss[!!PageAnon(page)]++; 458 } 459 460out_set_pte: 461 set_pte_at(dst_mm, addr, dst_pte, pte); 462} 463 464static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 465 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 466 unsigned long addr, unsigned long end) 467{ 468 pte_t *src_pte, *dst_pte; 469 spinlock_t *src_ptl, *dst_ptl; 470 int progress = 0; 471 int rss[2]; 472 473again: 474 rss[1] = rss[0] = 0; 475 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 476 if (!dst_pte) 477 return -ENOMEM; 478 src_pte = pte_offset_map_nested(src_pmd, addr); 479 src_ptl = pte_lockptr(src_mm, src_pmd); 480 spin_lock(src_ptl); 481 482 do { 483 /* 484 * We are holding two locks at this point - either of them 485 * could generate latencies in another task on another CPU. 486 */ 487 if (progress >= 32) { 488 progress = 0; 489 if (need_resched() || 490 need_lockbreak(src_ptl) || 491 need_lockbreak(dst_ptl)) 492 break; 493 } 494 if (pte_none(*src_pte)) { 495 progress++; 496 continue; 497 } 498 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 499 progress += 8; 500 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 501 502 spin_unlock(src_ptl); 503 pte_unmap_nested(src_pte - 1); 504 add_mm_rss(dst_mm, rss[0], rss[1]); 505 pte_unmap_unlock(dst_pte - 1, dst_ptl); 506 cond_resched(); 507 if (addr != end) 508 goto again; 509 return 0; 510} 511 512static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 513 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 514 unsigned long addr, unsigned long end) 515{ 516 pmd_t *src_pmd, *dst_pmd; 517 unsigned long next; 518 519 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 520 if (!dst_pmd) 521 return -ENOMEM; 522 src_pmd = pmd_offset(src_pud, addr); 523 do { 524 next = pmd_addr_end(addr, end); 525 if (pmd_none_or_clear_bad(src_pmd)) 526 continue; 527 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 528 vma, addr, next)) 529 return -ENOMEM; 530 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 531 return 0; 532} 533 534static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 535 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 536 unsigned long addr, unsigned long end) 537{ 538 pud_t *src_pud, *dst_pud; 539 unsigned long next; 540 541 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 542 if (!dst_pud) 543 return -ENOMEM; 544 src_pud = pud_offset(src_pgd, addr); 545 do { 546 next = pud_addr_end(addr, end); 547 if (pud_none_or_clear_bad(src_pud)) 548 continue; 549 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 550 vma, addr, next)) 551 return -ENOMEM; 552 } while (dst_pud++, src_pud++, addr = next, addr != end); 553 return 0; 554} 555 556int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 557 struct vm_area_struct *vma) 558{ 559 pgd_t *src_pgd, *dst_pgd; 560 unsigned long next; 561 unsigned long addr = vma->vm_start; 562 unsigned long end = vma->vm_end; 563 564 /* 565 * Don't copy ptes where a page fault will fill them correctly. 566 * Fork becomes much lighter when there are big shared or private 567 * readonly mappings. The tradeoff is that copy_page_range is more 568 * efficient than faulting. 569 */ 570 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP))) { 571 if (!vma->anon_vma) 572 return 0; 573 } 574 575 if (is_vm_hugetlb_page(vma)) 576 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 577 578 dst_pgd = pgd_offset(dst_mm, addr); 579 src_pgd = pgd_offset(src_mm, addr); 580 do { 581 next = pgd_addr_end(addr, end); 582 if (pgd_none_or_clear_bad(src_pgd)) 583 continue; 584 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 585 vma, addr, next)) 586 return -ENOMEM; 587 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 588 return 0; 589} 590 591static unsigned long zap_pte_range(struct mmu_gather *tlb, 592 struct vm_area_struct *vma, pmd_t *pmd, 593 unsigned long addr, unsigned long end, 594 long *zap_work, struct zap_details *details) 595{ 596 struct mm_struct *mm = tlb->mm; 597 pte_t *pte; 598 spinlock_t *ptl; 599 int file_rss = 0; 600 int anon_rss = 0; 601 602 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 603 do { 604 pte_t ptent = *pte; 605 if (pte_none(ptent)) { 606 (*zap_work)--; 607 continue; 608 } 609 if (pte_present(ptent)) { 610 struct page *page; 611 612 (*zap_work) -= PAGE_SIZE; 613 614 page = vm_normal_page(vma, addr, ptent); 615 if (unlikely(details) && page) { 616 /* 617 * unmap_shared_mapping_pages() wants to 618 * invalidate cache without truncating: 619 * unmap shared but keep private pages. 620 */ 621 if (details->check_mapping && 622 details->check_mapping != page->mapping) 623 continue; 624 /* 625 * Each page->index must be checked when 626 * invalidating or truncating nonlinear. 627 */ 628 if (details->nonlinear_vma && 629 (page->index < details->first_index || 630 page->index > details->last_index)) 631 continue; 632 } 633 ptent = ptep_get_and_clear_full(mm, addr, pte, 634 tlb->fullmm); 635 tlb_remove_tlb_entry(tlb, pte, addr); 636 if (unlikely(!page)) 637 continue; 638 if (unlikely(details) && details->nonlinear_vma 639 && linear_page_index(details->nonlinear_vma, 640 addr) != page->index) 641 set_pte_at(mm, addr, pte, 642 pgoff_to_pte(page->index)); 643 if (PageAnon(page)) 644 anon_rss--; 645 else { 646 if (pte_dirty(ptent)) 647 set_page_dirty(page); 648 if (pte_young(ptent)) 649 mark_page_accessed(page); 650 file_rss--; 651 } 652 page_remove_rmap(page); 653 tlb_remove_page(tlb, page); 654 continue; 655 } 656 /* 657 * If details->check_mapping, we leave swap entries; 658 * if details->nonlinear_vma, we leave file entries. 659 */ 660 if (unlikely(details)) 661 continue; 662 if (!pte_file(ptent)) 663 free_swap_and_cache(pte_to_swp_entry(ptent)); 664 pte_clear_full(mm, addr, pte, tlb->fullmm); 665 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 666 667 add_mm_rss(mm, file_rss, anon_rss); 668 pte_unmap_unlock(pte - 1, ptl); 669 670 return addr; 671} 672 673static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 674 struct vm_area_struct *vma, pud_t *pud, 675 unsigned long addr, unsigned long end, 676 long *zap_work, struct zap_details *details) 677{ 678 pmd_t *pmd; 679 unsigned long next; 680 681 pmd = pmd_offset(pud, addr); 682 do { 683 next = pmd_addr_end(addr, end); 684 if (pmd_none_or_clear_bad(pmd)) { 685 (*zap_work)--; 686 continue; 687 } 688 next = zap_pte_range(tlb, vma, pmd, addr, next, 689 zap_work, details); 690 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 691 692 return addr; 693} 694 695static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 696 struct vm_area_struct *vma, pgd_t *pgd, 697 unsigned long addr, unsigned long end, 698 long *zap_work, struct zap_details *details) 699{ 700 pud_t *pud; 701 unsigned long next; 702 703 pud = pud_offset(pgd, addr); 704 do { 705 next = pud_addr_end(addr, end); 706 if (pud_none_or_clear_bad(pud)) { 707 (*zap_work)--; 708 continue; 709 } 710 next = zap_pmd_range(tlb, vma, pud, addr, next, 711 zap_work, details); 712 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 713 714 return addr; 715} 716 717static unsigned long unmap_page_range(struct mmu_gather *tlb, 718 struct vm_area_struct *vma, 719 unsigned long addr, unsigned long end, 720 long *zap_work, struct zap_details *details) 721{ 722 pgd_t *pgd; 723 unsigned long next; 724 725 if (details && !details->check_mapping && !details->nonlinear_vma) 726 details = NULL; 727 728 BUG_ON(addr >= end); 729 tlb_start_vma(tlb, vma); 730 pgd = pgd_offset(vma->vm_mm, addr); 731 do { 732 next = pgd_addr_end(addr, end); 733 if (pgd_none_or_clear_bad(pgd)) { 734 (*zap_work)--; 735 continue; 736 } 737 next = zap_pud_range(tlb, vma, pgd, addr, next, 738 zap_work, details); 739 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 740 tlb_end_vma(tlb, vma); 741 742 return addr; 743} 744 745#ifdef CONFIG_PREEMPT 746# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 747#else 748/* No preempt: go for improved straight-line efficiency */ 749# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 750#endif 751 752/** 753 * unmap_vmas - unmap a range of memory covered by a list of vma's 754 * @tlbp: address of the caller's struct mmu_gather 755 * @vma: the starting vma 756 * @start_addr: virtual address at which to start unmapping 757 * @end_addr: virtual address at which to end unmapping 758 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 759 * @details: details of nonlinear truncation or shared cache invalidation 760 * 761 * Returns the end address of the unmapping (restart addr if interrupted). 762 * 763 * Unmap all pages in the vma list. 764 * 765 * We aim to not hold locks for too long (for scheduling latency reasons). 766 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 767 * return the ending mmu_gather to the caller. 768 * 769 * Only addresses between `start' and `end' will be unmapped. 770 * 771 * The VMA list must be sorted in ascending virtual address order. 772 * 773 * unmap_vmas() assumes that the caller will flush the whole unmapped address 774 * range after unmap_vmas() returns. So the only responsibility here is to 775 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 776 * drops the lock and schedules. 777 */ 778unsigned long unmap_vmas(struct mmu_gather **tlbp, 779 struct vm_area_struct *vma, unsigned long start_addr, 780 unsigned long end_addr, unsigned long *nr_accounted, 781 struct zap_details *details) 782{ 783 long zap_work = ZAP_BLOCK_SIZE; 784 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 785 int tlb_start_valid = 0; 786 unsigned long start = start_addr; 787 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 788 int fullmm = (*tlbp)->fullmm; 789 790 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 791 unsigned long end; 792 793 start = max(vma->vm_start, start_addr); 794 if (start >= vma->vm_end) 795 continue; 796 end = min(vma->vm_end, end_addr); 797 if (end <= vma->vm_start) 798 continue; 799 800 if (vma->vm_flags & VM_ACCOUNT) 801 *nr_accounted += (end - start) >> PAGE_SHIFT; 802 803 while (start != end) { 804 if (!tlb_start_valid) { 805 tlb_start = start; 806 tlb_start_valid = 1; 807 } 808 809 if (unlikely(is_vm_hugetlb_page(vma))) { 810 unmap_hugepage_range(vma, start, end); 811 zap_work -= (end - start) / 812 (HPAGE_SIZE / PAGE_SIZE); 813 start = end; 814 } else 815 start = unmap_page_range(*tlbp, vma, 816 start, end, &zap_work, details); 817 818 if (zap_work > 0) { 819 BUG_ON(start != end); 820 break; 821 } 822 823 tlb_finish_mmu(*tlbp, tlb_start, start); 824 825 if (need_resched() || 826 (i_mmap_lock && need_lockbreak(i_mmap_lock))) { 827 if (i_mmap_lock) { 828 *tlbp = NULL; 829 goto out; 830 } 831 cond_resched(); 832 } 833 834 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 835 tlb_start_valid = 0; 836 zap_work = ZAP_BLOCK_SIZE; 837 } 838 } 839out: 840 return start; /* which is now the end (or restart) address */ 841} 842 843/** 844 * zap_page_range - remove user pages in a given range 845 * @vma: vm_area_struct holding the applicable pages 846 * @address: starting address of pages to zap 847 * @size: number of bytes to zap 848 * @details: details of nonlinear truncation or shared cache invalidation 849 */ 850unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 851 unsigned long size, struct zap_details *details) 852{ 853 struct mm_struct *mm = vma->vm_mm; 854 struct mmu_gather *tlb; 855 unsigned long end = address + size; 856 unsigned long nr_accounted = 0; 857 858 lru_add_drain(); 859 tlb = tlb_gather_mmu(mm, 0); 860 update_hiwater_rss(mm); 861 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 862 if (tlb) 863 tlb_finish_mmu(tlb, address, end); 864 return end; 865} 866 867/* 868 * Do a quick page-table lookup for a single page. 869 */ 870struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 871 unsigned int flags) 872{ 873 pgd_t *pgd; 874 pud_t *pud; 875 pmd_t *pmd; 876 pte_t *ptep, pte; 877 spinlock_t *ptl; 878 struct page *page; 879 struct mm_struct *mm = vma->vm_mm; 880 881 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 882 if (!IS_ERR(page)) { 883 BUG_ON(flags & FOLL_GET); 884 goto out; 885 } 886 887 page = NULL; 888 pgd = pgd_offset(mm, address); 889 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 890 goto no_page_table; 891 892 pud = pud_offset(pgd, address); 893 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 894 goto no_page_table; 895 896 pmd = pmd_offset(pud, address); 897 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 898 goto no_page_table; 899 900 if (pmd_huge(*pmd)) { 901 BUG_ON(flags & FOLL_GET); 902 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 903 goto out; 904 } 905 906 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 907 if (!ptep) 908 goto out; 909 910 pte = *ptep; 911 if (!pte_present(pte)) 912 goto unlock; 913 if ((flags & FOLL_WRITE) && !pte_write(pte)) 914 goto unlock; 915 page = vm_normal_page(vma, address, pte); 916 if (unlikely(!page)) 917 goto unlock; 918 919 if (flags & FOLL_GET) 920 get_page(page); 921 if (flags & FOLL_TOUCH) { 922 if ((flags & FOLL_WRITE) && 923 !pte_dirty(pte) && !PageDirty(page)) 924 set_page_dirty(page); 925 mark_page_accessed(page); 926 } 927unlock: 928 pte_unmap_unlock(ptep, ptl); 929out: 930 return page; 931 932no_page_table: 933 /* 934 * When core dumping an enormous anonymous area that nobody 935 * has touched so far, we don't want to allocate page tables. 936 */ 937 if (flags & FOLL_ANON) { 938 page = ZERO_PAGE(address); 939 if (flags & FOLL_GET) 940 get_page(page); 941 BUG_ON(flags & FOLL_WRITE); 942 } 943 return page; 944} 945 946int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 947 unsigned long start, int len, int write, int force, 948 struct page **pages, struct vm_area_struct **vmas) 949{ 950 int i; 951 unsigned int vm_flags; 952 953 /* 954 * Require read or write permissions. 955 * If 'force' is set, we only require the "MAY" flags. 956 */ 957 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 958 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 959 i = 0; 960 961 do { 962 struct vm_area_struct *vma; 963 unsigned int foll_flags; 964 965 vma = find_extend_vma(mm, start); 966 if (!vma && in_gate_area(tsk, start)) { 967 unsigned long pg = start & PAGE_MASK; 968 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 969 pgd_t *pgd; 970 pud_t *pud; 971 pmd_t *pmd; 972 pte_t *pte; 973 if (write) /* user gate pages are read-only */ 974 return i ? : -EFAULT; 975 if (pg > TASK_SIZE) 976 pgd = pgd_offset_k(pg); 977 else 978 pgd = pgd_offset_gate(mm, pg); 979 BUG_ON(pgd_none(*pgd)); 980 pud = pud_offset(pgd, pg); 981 BUG_ON(pud_none(*pud)); 982 pmd = pmd_offset(pud, pg); 983 if (pmd_none(*pmd)) 984 return i ? : -EFAULT; 985 pte = pte_offset_map(pmd, pg); 986 if (pte_none(*pte)) { 987 pte_unmap(pte); 988 return i ? : -EFAULT; 989 } 990 if (pages) { 991 struct page *page = vm_normal_page(gate_vma, start, *pte); 992 pages[i] = page; 993 if (page) 994 get_page(page); 995 } 996 pte_unmap(pte); 997 if (vmas) 998 vmas[i] = gate_vma; 999 i++; 1000 start += PAGE_SIZE; 1001 len--; 1002 continue; 1003 } 1004 1005 if (!vma || (vma->vm_flags & VM_IO) 1006 || !(vm_flags & vma->vm_flags)) 1007 return i ? : -EFAULT; 1008 1009 if (is_vm_hugetlb_page(vma)) { 1010 i = follow_hugetlb_page(mm, vma, pages, vmas, 1011 &start, &len, i); 1012 continue; 1013 } 1014 1015 foll_flags = FOLL_TOUCH; 1016 if (pages) 1017 foll_flags |= FOLL_GET; 1018 if (!write && !(vma->vm_flags & VM_LOCKED) && 1019 (!vma->vm_ops || !vma->vm_ops->nopage)) 1020 foll_flags |= FOLL_ANON; 1021 1022 do { 1023 struct page *page; 1024 1025 if (write) 1026 foll_flags |= FOLL_WRITE; 1027 1028 cond_resched(); 1029 while (!(page = follow_page(vma, start, foll_flags))) { 1030 int ret; 1031 ret = __handle_mm_fault(mm, vma, start, 1032 foll_flags & FOLL_WRITE); 1033 /* 1034 * The VM_FAULT_WRITE bit tells us that do_wp_page has 1035 * broken COW when necessary, even if maybe_mkwrite 1036 * decided not to set pte_write. We can thus safely do 1037 * subsequent page lookups as if they were reads. 1038 */ 1039 if (ret & VM_FAULT_WRITE) 1040 foll_flags &= ~FOLL_WRITE; 1041 1042 switch (ret & ~VM_FAULT_WRITE) { 1043 case VM_FAULT_MINOR: 1044 tsk->min_flt++; 1045 break; 1046 case VM_FAULT_MAJOR: 1047 tsk->maj_flt++; 1048 break; 1049 case VM_FAULT_SIGBUS: 1050 return i ? i : -EFAULT; 1051 case VM_FAULT_OOM: 1052 return i ? i : -ENOMEM; 1053 default: 1054 BUG(); 1055 } 1056 } 1057 if (pages) { 1058 pages[i] = page; 1059 flush_dcache_page(page); 1060 } 1061 if (vmas) 1062 vmas[i] = vma; 1063 i++; 1064 start += PAGE_SIZE; 1065 len--; 1066 } while (len && start < vma->vm_end); 1067 } while (len); 1068 return i; 1069} 1070EXPORT_SYMBOL(get_user_pages); 1071 1072static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1073 unsigned long addr, unsigned long end, pgprot_t prot) 1074{ 1075 pte_t *pte; 1076 spinlock_t *ptl; 1077 1078 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1079 if (!pte) 1080 return -ENOMEM; 1081 do { 1082 struct page *page = ZERO_PAGE(addr); 1083 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot)); 1084 page_cache_get(page); 1085 page_add_file_rmap(page); 1086 inc_mm_counter(mm, file_rss); 1087 BUG_ON(!pte_none(*pte)); 1088 set_pte_at(mm, addr, pte, zero_pte); 1089 } while (pte++, addr += PAGE_SIZE, addr != end); 1090 pte_unmap_unlock(pte - 1, ptl); 1091 return 0; 1092} 1093 1094static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud, 1095 unsigned long addr, unsigned long end, pgprot_t prot) 1096{ 1097 pmd_t *pmd; 1098 unsigned long next; 1099 1100 pmd = pmd_alloc(mm, pud, addr); 1101 if (!pmd) 1102 return -ENOMEM; 1103 do { 1104 next = pmd_addr_end(addr, end); 1105 if (zeromap_pte_range(mm, pmd, addr, next, prot)) 1106 return -ENOMEM; 1107 } while (pmd++, addr = next, addr != end); 1108 return 0; 1109} 1110 1111static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1112 unsigned long addr, unsigned long end, pgprot_t prot) 1113{ 1114 pud_t *pud; 1115 unsigned long next; 1116 1117 pud = pud_alloc(mm, pgd, addr); 1118 if (!pud) 1119 return -ENOMEM; 1120 do { 1121 next = pud_addr_end(addr, end); 1122 if (zeromap_pmd_range(mm, pud, addr, next, prot)) 1123 return -ENOMEM; 1124 } while (pud++, addr = next, addr != end); 1125 return 0; 1126} 1127 1128int zeromap_page_range(struct vm_area_struct *vma, 1129 unsigned long addr, unsigned long size, pgprot_t prot) 1130{ 1131 pgd_t *pgd; 1132 unsigned long next; 1133 unsigned long end = addr + size; 1134 struct mm_struct *mm = vma->vm_mm; 1135 int err; 1136 1137 BUG_ON(addr >= end); 1138 pgd = pgd_offset(mm, addr); 1139 flush_cache_range(vma, addr, end); 1140 do { 1141 next = pgd_addr_end(addr, end); 1142 err = zeromap_pud_range(mm, pgd, addr, next, prot); 1143 if (err) 1144 break; 1145 } while (pgd++, addr = next, addr != end); 1146 return err; 1147} 1148 1149pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl) 1150{ 1151 pgd_t * pgd = pgd_offset(mm, addr); 1152 pud_t * pud = pud_alloc(mm, pgd, addr); 1153 if (pud) { 1154 pmd_t * pmd = pmd_alloc(mm, pgd, addr); 1155 if (pmd) 1156 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1157 } 1158 return NULL; 1159} 1160 1161/* 1162 * This is the old fallback for page remapping. 1163 * 1164 * For historical reasons, it only allows reserved pages. Only 1165 * old drivers should use this, and they needed to mark their 1166 * pages reserved for the old functions anyway. 1167 */ 1168static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot) 1169{ 1170 int retval; 1171 pte_t *pte; 1172 spinlock_t *ptl; 1173 1174 retval = -EINVAL; 1175 if (PageAnon(page) || !PageReserved(page)) 1176 goto out; 1177 retval = -ENOMEM; 1178 flush_dcache_page(page); 1179 pte = get_locked_pte(mm, addr, &ptl); 1180 if (!pte) 1181 goto out; 1182 retval = -EBUSY; 1183 if (!pte_none(*pte)) 1184 goto out_unlock; 1185 1186 /* Ok, finally just insert the thing.. */ 1187 get_page(page); 1188 inc_mm_counter(mm, file_rss); 1189 page_add_file_rmap(page); 1190 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1191 1192 retval = 0; 1193out_unlock: 1194 pte_unmap_unlock(pte, ptl); 1195out: 1196 return retval; 1197} 1198 1199/* 1200 * Somebody does a pfn remapping that doesn't actually work as a vma. 1201 * 1202 * Do it as individual pages instead, and warn about it. It's bad form, 1203 * and very inefficient. 1204 */ 1205static int incomplete_pfn_remap(struct vm_area_struct *vma, 1206 unsigned long start, unsigned long end, 1207 unsigned long pfn, pgprot_t prot) 1208{ 1209 static int warn = 10; 1210 struct page *page; 1211 int retval; 1212 1213 if (!(vma->vm_flags & VM_INCOMPLETE)) { 1214 if (warn) { 1215 warn--; 1216 printk("%s does an incomplete pfn remapping", current->comm); 1217 dump_stack(); 1218 } 1219 } 1220 vma->vm_flags |= VM_INCOMPLETE | VM_IO | VM_RESERVED; 1221 1222 if (start < vma->vm_start || end > vma->vm_end) 1223 return -EINVAL; 1224 1225 if (!pfn_valid(pfn)) 1226 return -EINVAL; 1227 1228 retval = 0; 1229 page = pfn_to_page(pfn); 1230 while (start < end) { 1231 retval = insert_page(vma->vm_mm, start, page, prot); 1232 if (retval < 0) 1233 break; 1234 start += PAGE_SIZE; 1235 page++; 1236 } 1237 return retval; 1238} 1239 1240/* 1241 * maps a range of physical memory into the requested pages. the old 1242 * mappings are removed. any references to nonexistent pages results 1243 * in null mappings (currently treated as "copy-on-access") 1244 */ 1245static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1246 unsigned long addr, unsigned long end, 1247 unsigned long pfn, pgprot_t prot) 1248{ 1249 pte_t *pte; 1250 spinlock_t *ptl; 1251 1252 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1253 if (!pte) 1254 return -ENOMEM; 1255 do { 1256 BUG_ON(!pte_none(*pte)); 1257 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); 1258 pfn++; 1259 } while (pte++, addr += PAGE_SIZE, addr != end); 1260 pte_unmap_unlock(pte - 1, ptl); 1261 return 0; 1262} 1263 1264static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1265 unsigned long addr, unsigned long end, 1266 unsigned long pfn, pgprot_t prot) 1267{ 1268 pmd_t *pmd; 1269 unsigned long next; 1270 1271 pfn -= addr >> PAGE_SHIFT; 1272 pmd = pmd_alloc(mm, pud, addr); 1273 if (!pmd) 1274 return -ENOMEM; 1275 do { 1276 next = pmd_addr_end(addr, end); 1277 if (remap_pte_range(mm, pmd, addr, next, 1278 pfn + (addr >> PAGE_SHIFT), prot)) 1279 return -ENOMEM; 1280 } while (pmd++, addr = next, addr != end); 1281 return 0; 1282} 1283 1284static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1285 unsigned long addr, unsigned long end, 1286 unsigned long pfn, pgprot_t prot) 1287{ 1288 pud_t *pud; 1289 unsigned long next; 1290 1291 pfn -= addr >> PAGE_SHIFT; 1292 pud = pud_alloc(mm, pgd, addr); 1293 if (!pud) 1294 return -ENOMEM; 1295 do { 1296 next = pud_addr_end(addr, end); 1297 if (remap_pmd_range(mm, pud, addr, next, 1298 pfn + (addr >> PAGE_SHIFT), prot)) 1299 return -ENOMEM; 1300 } while (pud++, addr = next, addr != end); 1301 return 0; 1302} 1303 1304/* Note: this is only safe if the mm semaphore is held when called. */ 1305int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1306 unsigned long pfn, unsigned long size, pgprot_t prot) 1307{ 1308 pgd_t *pgd; 1309 unsigned long next; 1310 unsigned long end = addr + PAGE_ALIGN(size); 1311 struct mm_struct *mm = vma->vm_mm; 1312 int err; 1313 1314 if (addr != vma->vm_start || end != vma->vm_end) 1315 return incomplete_pfn_remap(vma, addr, end, pfn, prot); 1316 1317 /* 1318 * Physically remapped pages are special. Tell the 1319 * rest of the world about it: 1320 * VM_IO tells people not to look at these pages 1321 * (accesses can have side effects). 1322 * VM_RESERVED is specified all over the place, because 1323 * in 2.4 it kept swapout's vma scan off this vma; but 1324 * in 2.6 the LRU scan won't even find its pages, so this 1325 * flag means no more than count its pages in reserved_vm, 1326 * and omit it from core dump, even when VM_IO turned off. 1327 * VM_PFNMAP tells the core MM that the base pages are just 1328 * raw PFN mappings, and do not have a "struct page" associated 1329 * with them. 1330 */ 1331 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 1332 vma->vm_pgoff = pfn; 1333 1334 BUG_ON(addr >= end); 1335 pfn -= addr >> PAGE_SHIFT; 1336 pgd = pgd_offset(mm, addr); 1337 flush_cache_range(vma, addr, end); 1338 do { 1339 next = pgd_addr_end(addr, end); 1340 err = remap_pud_range(mm, pgd, addr, next, 1341 pfn + (addr >> PAGE_SHIFT), prot); 1342 if (err) 1343 break; 1344 } while (pgd++, addr = next, addr != end); 1345 return err; 1346} 1347EXPORT_SYMBOL(remap_pfn_range); 1348 1349/* 1350 * handle_pte_fault chooses page fault handler according to an entry 1351 * which was read non-atomically. Before making any commitment, on 1352 * those architectures or configurations (e.g. i386 with PAE) which 1353 * might give a mix of unmatched parts, do_swap_page and do_file_page 1354 * must check under lock before unmapping the pte and proceeding 1355 * (but do_wp_page is only called after already making such a check; 1356 * and do_anonymous_page and do_no_page can safely check later on). 1357 */ 1358static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1359 pte_t *page_table, pte_t orig_pte) 1360{ 1361 int same = 1; 1362#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1363 if (sizeof(pte_t) > sizeof(unsigned long)) { 1364 spinlock_t *ptl = pte_lockptr(mm, pmd); 1365 spin_lock(ptl); 1366 same = pte_same(*page_table, orig_pte); 1367 spin_unlock(ptl); 1368 } 1369#endif 1370 pte_unmap(page_table); 1371 return same; 1372} 1373 1374/* 1375 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1376 * servicing faults for write access. In the normal case, do always want 1377 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1378 * that do not have writing enabled, when used by access_process_vm. 1379 */ 1380static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1381{ 1382 if (likely(vma->vm_flags & VM_WRITE)) 1383 pte = pte_mkwrite(pte); 1384 return pte; 1385} 1386 1387static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va) 1388{ 1389 /* 1390 * If the source page was a PFN mapping, we don't have 1391 * a "struct page" for it. We do a best-effort copy by 1392 * just copying from the original user address. If that 1393 * fails, we just zero-fill it. Live with it. 1394 */ 1395 if (unlikely(!src)) { 1396 void *kaddr = kmap_atomic(dst, KM_USER0); 1397 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1398 1399 /* 1400 * This really shouldn't fail, because the page is there 1401 * in the page tables. But it might just be unreadable, 1402 * in which case we just give up and fill the result with 1403 * zeroes. 1404 */ 1405 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1406 memset(kaddr, 0, PAGE_SIZE); 1407 kunmap_atomic(kaddr, KM_USER0); 1408 return; 1409 1410 } 1411 copy_user_highpage(dst, src, va); 1412} 1413 1414/* 1415 * This routine handles present pages, when users try to write 1416 * to a shared page. It is done by copying the page to a new address 1417 * and decrementing the shared-page counter for the old page. 1418 * 1419 * Note that this routine assumes that the protection checks have been 1420 * done by the caller (the low-level page fault routine in most cases). 1421 * Thus we can safely just mark it writable once we've done any necessary 1422 * COW. 1423 * 1424 * We also mark the page dirty at this point even though the page will 1425 * change only once the write actually happens. This avoids a few races, 1426 * and potentially makes it more efficient. 1427 * 1428 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1429 * but allow concurrent faults), with pte both mapped and locked. 1430 * We return with mmap_sem still held, but pte unmapped and unlocked. 1431 */ 1432static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1433 unsigned long address, pte_t *page_table, pmd_t *pmd, 1434 spinlock_t *ptl, pte_t orig_pte) 1435{ 1436 struct page *old_page, *src_page, *new_page; 1437 pte_t entry; 1438 int ret = VM_FAULT_MINOR; 1439 1440 old_page = vm_normal_page(vma, address, orig_pte); 1441 src_page = old_page; 1442 if (!old_page) 1443 goto gotten; 1444 1445 if (PageAnon(old_page) && !TestSetPageLocked(old_page)) { 1446 int reuse = can_share_swap_page(old_page); 1447 unlock_page(old_page); 1448 if (reuse) { 1449 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1450 entry = pte_mkyoung(orig_pte); 1451 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1452 ptep_set_access_flags(vma, address, page_table, entry, 1); 1453 update_mmu_cache(vma, address, entry); 1454 lazy_mmu_prot_update(entry); 1455 ret |= VM_FAULT_WRITE; 1456 goto unlock; 1457 } 1458 } 1459 1460 /* 1461 * Ok, we need to copy. Oh, well.. 1462 */ 1463 page_cache_get(old_page); 1464gotten: 1465 pte_unmap_unlock(page_table, ptl); 1466 1467 if (unlikely(anon_vma_prepare(vma))) 1468 goto oom; 1469 if (src_page == ZERO_PAGE(address)) { 1470 new_page = alloc_zeroed_user_highpage(vma, address); 1471 if (!new_page) 1472 goto oom; 1473 } else { 1474 new_page = alloc_page_vma(GFP_HIGHUSER, vma, address); 1475 if (!new_page) 1476 goto oom; 1477 cow_user_page(new_page, src_page, address); 1478 } 1479 1480 /* 1481 * Re-check the pte - we dropped the lock 1482 */ 1483 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1484 if (likely(pte_same(*page_table, orig_pte))) { 1485 if (old_page) { 1486 page_remove_rmap(old_page); 1487 if (!PageAnon(old_page)) { 1488 dec_mm_counter(mm, file_rss); 1489 inc_mm_counter(mm, anon_rss); 1490 } 1491 } else 1492 inc_mm_counter(mm, anon_rss); 1493 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1494 entry = mk_pte(new_page, vma->vm_page_prot); 1495 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1496 ptep_establish(vma, address, page_table, entry); 1497 update_mmu_cache(vma, address, entry); 1498 lazy_mmu_prot_update(entry); 1499 lru_cache_add_active(new_page); 1500 page_add_anon_rmap(new_page, vma, address); 1501 1502 /* Free the old page.. */ 1503 new_page = old_page; 1504 ret |= VM_FAULT_WRITE; 1505 } 1506 if (new_page) 1507 page_cache_release(new_page); 1508 if (old_page) 1509 page_cache_release(old_page); 1510unlock: 1511 pte_unmap_unlock(page_table, ptl); 1512 return ret; 1513oom: 1514 if (old_page) 1515 page_cache_release(old_page); 1516 return VM_FAULT_OOM; 1517} 1518 1519/* 1520 * Helper functions for unmap_mapping_range(). 1521 * 1522 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 1523 * 1524 * We have to restart searching the prio_tree whenever we drop the lock, 1525 * since the iterator is only valid while the lock is held, and anyway 1526 * a later vma might be split and reinserted earlier while lock dropped. 1527 * 1528 * The list of nonlinear vmas could be handled more efficiently, using 1529 * a placeholder, but handle it in the same way until a need is shown. 1530 * It is important to search the prio_tree before nonlinear list: a vma 1531 * may become nonlinear and be shifted from prio_tree to nonlinear list 1532 * while the lock is dropped; but never shifted from list to prio_tree. 1533 * 1534 * In order to make forward progress despite restarting the search, 1535 * vm_truncate_count is used to mark a vma as now dealt with, so we can 1536 * quickly skip it next time around. Since the prio_tree search only 1537 * shows us those vmas affected by unmapping the range in question, we 1538 * can't efficiently keep all vmas in step with mapping->truncate_count: 1539 * so instead reset them all whenever it wraps back to 0 (then go to 1). 1540 * mapping->truncate_count and vma->vm_truncate_count are protected by 1541 * i_mmap_lock. 1542 * 1543 * In order to make forward progress despite repeatedly restarting some 1544 * large vma, note the restart_addr from unmap_vmas when it breaks out: 1545 * and restart from that address when we reach that vma again. It might 1546 * have been split or merged, shrunk or extended, but never shifted: so 1547 * restart_addr remains valid so long as it remains in the vma's range. 1548 * unmap_mapping_range forces truncate_count to leap over page-aligned 1549 * values so we can save vma's restart_addr in its truncate_count field. 1550 */ 1551#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 1552 1553static void reset_vma_truncate_counts(struct address_space *mapping) 1554{ 1555 struct vm_area_struct *vma; 1556 struct prio_tree_iter iter; 1557 1558 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 1559 vma->vm_truncate_count = 0; 1560 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 1561 vma->vm_truncate_count = 0; 1562} 1563 1564static int unmap_mapping_range_vma(struct vm_area_struct *vma, 1565 unsigned long start_addr, unsigned long end_addr, 1566 struct zap_details *details) 1567{ 1568 unsigned long restart_addr; 1569 int need_break; 1570 1571again: 1572 restart_addr = vma->vm_truncate_count; 1573 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 1574 start_addr = restart_addr; 1575 if (start_addr >= end_addr) { 1576 /* Top of vma has been split off since last time */ 1577 vma->vm_truncate_count = details->truncate_count; 1578 return 0; 1579 } 1580 } 1581 1582 restart_addr = zap_page_range(vma, start_addr, 1583 end_addr - start_addr, details); 1584 need_break = need_resched() || 1585 need_lockbreak(details->i_mmap_lock); 1586 1587 if (restart_addr >= end_addr) { 1588 /* We have now completed this vma: mark it so */ 1589 vma->vm_truncate_count = details->truncate_count; 1590 if (!need_break) 1591 return 0; 1592 } else { 1593 /* Note restart_addr in vma's truncate_count field */ 1594 vma->vm_truncate_count = restart_addr; 1595 if (!need_break) 1596 goto again; 1597 } 1598 1599 spin_unlock(details->i_mmap_lock); 1600 cond_resched(); 1601 spin_lock(details->i_mmap_lock); 1602 return -EINTR; 1603} 1604 1605static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 1606 struct zap_details *details) 1607{ 1608 struct vm_area_struct *vma; 1609 struct prio_tree_iter iter; 1610 pgoff_t vba, vea, zba, zea; 1611 1612restart: 1613 vma_prio_tree_foreach(vma, &iter, root, 1614 details->first_index, details->last_index) { 1615 /* Skip quickly over those we have already dealt with */ 1616 if (vma->vm_truncate_count == details->truncate_count) 1617 continue; 1618 1619 vba = vma->vm_pgoff; 1620 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 1621 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 1622 zba = details->first_index; 1623 if (zba < vba) 1624 zba = vba; 1625 zea = details->last_index; 1626 if (zea > vea) 1627 zea = vea; 1628 1629 if (unmap_mapping_range_vma(vma, 1630 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 1631 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 1632 details) < 0) 1633 goto restart; 1634 } 1635} 1636 1637static inline void unmap_mapping_range_list(struct list_head *head, 1638 struct zap_details *details) 1639{ 1640 struct vm_area_struct *vma; 1641 1642 /* 1643 * In nonlinear VMAs there is no correspondence between virtual address 1644 * offset and file offset. So we must perform an exhaustive search 1645 * across *all* the pages in each nonlinear VMA, not just the pages 1646 * whose virtual address lies outside the file truncation point. 1647 */ 1648restart: 1649 list_for_each_entry(vma, head, shared.vm_set.list) { 1650 /* Skip quickly over those we have already dealt with */ 1651 if (vma->vm_truncate_count == details->truncate_count) 1652 continue; 1653 details->nonlinear_vma = vma; 1654 if (unmap_mapping_range_vma(vma, vma->vm_start, 1655 vma->vm_end, details) < 0) 1656 goto restart; 1657 } 1658} 1659 1660/** 1661 * unmap_mapping_range - unmap the portion of all mmaps 1662 * in the specified address_space corresponding to the specified 1663 * page range in the underlying file. 1664 * @mapping: the address space containing mmaps to be unmapped. 1665 * @holebegin: byte in first page to unmap, relative to the start of 1666 * the underlying file. This will be rounded down to a PAGE_SIZE 1667 * boundary. Note that this is different from vmtruncate(), which 1668 * must keep the partial page. In contrast, we must get rid of 1669 * partial pages. 1670 * @holelen: size of prospective hole in bytes. This will be rounded 1671 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 1672 * end of the file. 1673 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 1674 * but 0 when invalidating pagecache, don't throw away private data. 1675 */ 1676void unmap_mapping_range(struct address_space *mapping, 1677 loff_t const holebegin, loff_t const holelen, int even_cows) 1678{ 1679 struct zap_details details; 1680 pgoff_t hba = holebegin >> PAGE_SHIFT; 1681 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1682 1683 /* Check for overflow. */ 1684 if (sizeof(holelen) > sizeof(hlen)) { 1685 long long holeend = 1686 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1687 if (holeend & ~(long long)ULONG_MAX) 1688 hlen = ULONG_MAX - hba + 1; 1689 } 1690 1691 details.check_mapping = even_cows? NULL: mapping; 1692 details.nonlinear_vma = NULL; 1693 details.first_index = hba; 1694 details.last_index = hba + hlen - 1; 1695 if (details.last_index < details.first_index) 1696 details.last_index = ULONG_MAX; 1697 details.i_mmap_lock = &mapping->i_mmap_lock; 1698 1699 spin_lock(&mapping->i_mmap_lock); 1700 1701 /* serialize i_size write against truncate_count write */ 1702 smp_wmb(); 1703 /* Protect against page faults, and endless unmapping loops */ 1704 mapping->truncate_count++; 1705 /* 1706 * For archs where spin_lock has inclusive semantics like ia64 1707 * this smp_mb() will prevent to read pagetable contents 1708 * before the truncate_count increment is visible to 1709 * other cpus. 1710 */ 1711 smp_mb(); 1712 if (unlikely(is_restart_addr(mapping->truncate_count))) { 1713 if (mapping->truncate_count == 0) 1714 reset_vma_truncate_counts(mapping); 1715 mapping->truncate_count++; 1716 } 1717 details.truncate_count = mapping->truncate_count; 1718 1719 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 1720 unmap_mapping_range_tree(&mapping->i_mmap, &details); 1721 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 1722 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 1723 spin_unlock(&mapping->i_mmap_lock); 1724} 1725EXPORT_SYMBOL(unmap_mapping_range); 1726 1727/* 1728 * Handle all mappings that got truncated by a "truncate()" 1729 * system call. 1730 * 1731 * NOTE! We have to be ready to update the memory sharing 1732 * between the file and the memory map for a potential last 1733 * incomplete page. Ugly, but necessary. 1734 */ 1735int vmtruncate(struct inode * inode, loff_t offset) 1736{ 1737 struct address_space *mapping = inode->i_mapping; 1738 unsigned long limit; 1739 1740 if (inode->i_size < offset) 1741 goto do_expand; 1742 /* 1743 * truncation of in-use swapfiles is disallowed - it would cause 1744 * subsequent swapout to scribble on the now-freed blocks. 1745 */ 1746 if (IS_SWAPFILE(inode)) 1747 goto out_busy; 1748 i_size_write(inode, offset); 1749 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 1750 truncate_inode_pages(mapping, offset); 1751 goto out_truncate; 1752 1753do_expand: 1754 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 1755 if (limit != RLIM_INFINITY && offset > limit) 1756 goto out_sig; 1757 if (offset > inode->i_sb->s_maxbytes) 1758 goto out_big; 1759 i_size_write(inode, offset); 1760 1761out_truncate: 1762 if (inode->i_op && inode->i_op->truncate) 1763 inode->i_op->truncate(inode); 1764 return 0; 1765out_sig: 1766 send_sig(SIGXFSZ, current, 0); 1767out_big: 1768 return -EFBIG; 1769out_busy: 1770 return -ETXTBSY; 1771} 1772 1773EXPORT_SYMBOL(vmtruncate); 1774 1775/* 1776 * Primitive swap readahead code. We simply read an aligned block of 1777 * (1 << page_cluster) entries in the swap area. This method is chosen 1778 * because it doesn't cost us any seek time. We also make sure to queue 1779 * the 'original' request together with the readahead ones... 1780 * 1781 * This has been extended to use the NUMA policies from the mm triggering 1782 * the readahead. 1783 * 1784 * Caller must hold down_read on the vma->vm_mm if vma is not NULL. 1785 */ 1786void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) 1787{ 1788#ifdef CONFIG_NUMA 1789 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; 1790#endif 1791 int i, num; 1792 struct page *new_page; 1793 unsigned long offset; 1794 1795 /* 1796 * Get the number of handles we should do readahead io to. 1797 */ 1798 num = valid_swaphandles(entry, &offset); 1799 for (i = 0; i < num; offset++, i++) { 1800 /* Ok, do the async read-ahead now */ 1801 new_page = read_swap_cache_async(swp_entry(swp_type(entry), 1802 offset), vma, addr); 1803 if (!new_page) 1804 break; 1805 page_cache_release(new_page); 1806#ifdef CONFIG_NUMA 1807 /* 1808 * Find the next applicable VMA for the NUMA policy. 1809 */ 1810 addr += PAGE_SIZE; 1811 if (addr == 0) 1812 vma = NULL; 1813 if (vma) { 1814 if (addr >= vma->vm_end) { 1815 vma = next_vma; 1816 next_vma = vma ? vma->vm_next : NULL; 1817 } 1818 if (vma && addr < vma->vm_start) 1819 vma = NULL; 1820 } else { 1821 if (next_vma && addr >= next_vma->vm_start) { 1822 vma = next_vma; 1823 next_vma = vma->vm_next; 1824 } 1825 } 1826#endif 1827 } 1828 lru_add_drain(); /* Push any new pages onto the LRU now */ 1829} 1830 1831/* 1832 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1833 * but allow concurrent faults), and pte mapped but not yet locked. 1834 * We return with mmap_sem still held, but pte unmapped and unlocked. 1835 */ 1836static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 1837 unsigned long address, pte_t *page_table, pmd_t *pmd, 1838 int write_access, pte_t orig_pte) 1839{ 1840 spinlock_t *ptl; 1841 struct page *page; 1842 swp_entry_t entry; 1843 pte_t pte; 1844 int ret = VM_FAULT_MINOR; 1845 1846 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 1847 goto out; 1848 1849 entry = pte_to_swp_entry(orig_pte); 1850 page = lookup_swap_cache(entry); 1851 if (!page) { 1852 swapin_readahead(entry, address, vma); 1853 page = read_swap_cache_async(entry, vma, address); 1854 if (!page) { 1855 /* 1856 * Back out if somebody else faulted in this pte 1857 * while we released the pte lock. 1858 */ 1859 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1860 if (likely(pte_same(*page_table, orig_pte))) 1861 ret = VM_FAULT_OOM; 1862 goto unlock; 1863 } 1864 1865 /* Had to read the page from swap area: Major fault */ 1866 ret = VM_FAULT_MAJOR; 1867 inc_page_state(pgmajfault); 1868 grab_swap_token(); 1869 } 1870 1871 mark_page_accessed(page); 1872 lock_page(page); 1873 1874 /* 1875 * Back out if somebody else already faulted in this pte. 1876 */ 1877 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1878 if (unlikely(!pte_same(*page_table, orig_pte))) 1879 goto out_nomap; 1880 1881 if (unlikely(!PageUptodate(page))) { 1882 ret = VM_FAULT_SIGBUS; 1883 goto out_nomap; 1884 } 1885 1886 /* The page isn't present yet, go ahead with the fault. */ 1887 1888 inc_mm_counter(mm, anon_rss); 1889 pte = mk_pte(page, vma->vm_page_prot); 1890 if (write_access && can_share_swap_page(page)) { 1891 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 1892 write_access = 0; 1893 } 1894 1895 flush_icache_page(vma, page); 1896 set_pte_at(mm, address, page_table, pte); 1897 page_add_anon_rmap(page, vma, address); 1898 1899 swap_free(entry); 1900 if (vm_swap_full()) 1901 remove_exclusive_swap_page(page); 1902 unlock_page(page); 1903 1904 if (write_access) { 1905 if (do_wp_page(mm, vma, address, 1906 page_table, pmd, ptl, pte) == VM_FAULT_OOM) 1907 ret = VM_FAULT_OOM; 1908 goto out; 1909 } 1910 1911 /* No need to invalidate - it was non-present before */ 1912 update_mmu_cache(vma, address, pte); 1913 lazy_mmu_prot_update(pte); 1914unlock: 1915 pte_unmap_unlock(page_table, ptl); 1916out: 1917 return ret; 1918out_nomap: 1919 pte_unmap_unlock(page_table, ptl); 1920 unlock_page(page); 1921 page_cache_release(page); 1922 return ret; 1923} 1924 1925/* 1926 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1927 * but allow concurrent faults), and pte mapped but not yet locked. 1928 * We return with mmap_sem still held, but pte unmapped and unlocked. 1929 */ 1930static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 1931 unsigned long address, pte_t *page_table, pmd_t *pmd, 1932 int write_access) 1933{ 1934 struct page *page; 1935 spinlock_t *ptl; 1936 pte_t entry; 1937 1938 if (write_access) { 1939 /* Allocate our own private page. */ 1940 pte_unmap(page_table); 1941 1942 if (unlikely(anon_vma_prepare(vma))) 1943 goto oom; 1944 page = alloc_zeroed_user_highpage(vma, address); 1945 if (!page) 1946 goto oom; 1947 1948 entry = mk_pte(page, vma->vm_page_prot); 1949 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1950 1951 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1952 if (!pte_none(*page_table)) 1953 goto release; 1954 inc_mm_counter(mm, anon_rss); 1955 lru_cache_add_active(page); 1956 SetPageReferenced(page); 1957 page_add_anon_rmap(page, vma, address); 1958 } else { 1959 /* Map the ZERO_PAGE - vm_page_prot is readonly */ 1960 page = ZERO_PAGE(address); 1961 page_cache_get(page); 1962 entry = mk_pte(page, vma->vm_page_prot); 1963 1964 ptl = pte_lockptr(mm, pmd); 1965 spin_lock(ptl); 1966 if (!pte_none(*page_table)) 1967 goto release; 1968 inc_mm_counter(mm, file_rss); 1969 page_add_file_rmap(page); 1970 } 1971 1972 set_pte_at(mm, address, page_table, entry); 1973 1974 /* No need to invalidate - it was non-present before */ 1975 update_mmu_cache(vma, address, entry); 1976 lazy_mmu_prot_update(entry); 1977unlock: 1978 pte_unmap_unlock(page_table, ptl); 1979 return VM_FAULT_MINOR; 1980release: 1981 page_cache_release(page); 1982 goto unlock; 1983oom: 1984 return VM_FAULT_OOM; 1985} 1986 1987/* 1988 * do_no_page() tries to create a new page mapping. It aggressively 1989 * tries to share with existing pages, but makes a separate copy if 1990 * the "write_access" parameter is true in order to avoid the next 1991 * page fault. 1992 * 1993 * As this is called only for pages that do not currently exist, we 1994 * do not need to flush old virtual caches or the TLB. 1995 * 1996 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1997 * but allow concurrent faults), and pte mapped but not yet locked. 1998 * We return with mmap_sem still held, but pte unmapped and unlocked. 1999 */ 2000static int do_no_page(struct mm_struct *mm, struct vm_area_struct *vma, 2001 unsigned long address, pte_t *page_table, pmd_t *pmd, 2002 int write_access) 2003{ 2004 spinlock_t *ptl; 2005 struct page *new_page; 2006 struct address_space *mapping = NULL; 2007 pte_t entry; 2008 unsigned int sequence = 0; 2009 int ret = VM_FAULT_MINOR; 2010 int anon = 0; 2011 2012 pte_unmap(page_table); 2013 if (vma->vm_file) { 2014 mapping = vma->vm_file->f_mapping; 2015 sequence = mapping->truncate_count; 2016 smp_rmb(); /* serializes i_size against truncate_count */ 2017 } 2018retry: 2019 new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, &ret); 2020 /* 2021 * No smp_rmb is needed here as long as there's a full 2022 * spin_lock/unlock sequence inside the ->nopage callback 2023 * (for the pagecache lookup) that acts as an implicit 2024 * smp_mb() and prevents the i_size read to happen 2025 * after the next truncate_count read. 2026 */ 2027 2028 /* no page was available -- either SIGBUS or OOM */ 2029 if (new_page == NOPAGE_SIGBUS) 2030 return VM_FAULT_SIGBUS; 2031 if (new_page == NOPAGE_OOM) 2032 return VM_FAULT_OOM; 2033 2034 /* 2035 * Should we do an early C-O-W break? 2036 */ 2037 if (write_access && !(vma->vm_flags & VM_SHARED)) { 2038 struct page *page; 2039 2040 if (unlikely(anon_vma_prepare(vma))) 2041 goto oom; 2042 page = alloc_page_vma(GFP_HIGHUSER, vma, address); 2043 if (!page) 2044 goto oom; 2045 cow_user_page(page, new_page, address); 2046 page_cache_release(new_page); 2047 new_page = page; 2048 anon = 1; 2049 } 2050 2051 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2052 /* 2053 * For a file-backed vma, someone could have truncated or otherwise 2054 * invalidated this page. If unmap_mapping_range got called, 2055 * retry getting the page. 2056 */ 2057 if (mapping && unlikely(sequence != mapping->truncate_count)) { 2058 pte_unmap_unlock(page_table, ptl); 2059 page_cache_release(new_page); 2060 cond_resched(); 2061 sequence = mapping->truncate_count; 2062 smp_rmb(); 2063 goto retry; 2064 } 2065 2066 /* 2067 * This silly early PAGE_DIRTY setting removes a race 2068 * due to the bad i386 page protection. But it's valid 2069 * for other architectures too. 2070 * 2071 * Note that if write_access is true, we either now have 2072 * an exclusive copy of the page, or this is a shared mapping, 2073 * so we can make it writable and dirty to avoid having to 2074 * handle that later. 2075 */ 2076 /* Only go through if we didn't race with anybody else... */ 2077 if (pte_none(*page_table)) { 2078 flush_icache_page(vma, new_page); 2079 entry = mk_pte(new_page, vma->vm_page_prot); 2080 if (write_access) 2081 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2082 set_pte_at(mm, address, page_table, entry); 2083 if (anon) { 2084 inc_mm_counter(mm, anon_rss); 2085 lru_cache_add_active(new_page); 2086 page_add_anon_rmap(new_page, vma, address); 2087 } else { 2088 inc_mm_counter(mm, file_rss); 2089 page_add_file_rmap(new_page); 2090 } 2091 } else { 2092 /* One of our sibling threads was faster, back out. */ 2093 page_cache_release(new_page); 2094 goto unlock; 2095 } 2096 2097 /* no need to invalidate: a not-present page shouldn't be cached */ 2098 update_mmu_cache(vma, address, entry); 2099 lazy_mmu_prot_update(entry); 2100unlock: 2101 pte_unmap_unlock(page_table, ptl); 2102 return ret; 2103oom: 2104 page_cache_release(new_page); 2105 return VM_FAULT_OOM; 2106} 2107 2108/* 2109 * Fault of a previously existing named mapping. Repopulate the pte 2110 * from the encoded file_pte if possible. This enables swappable 2111 * nonlinear vmas. 2112 * 2113 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2114 * but allow concurrent faults), and pte mapped but not yet locked. 2115 * We return with mmap_sem still held, but pte unmapped and unlocked. 2116 */ 2117static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma, 2118 unsigned long address, pte_t *page_table, pmd_t *pmd, 2119 int write_access, pte_t orig_pte) 2120{ 2121 pgoff_t pgoff; 2122 int err; 2123 2124 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2125 return VM_FAULT_MINOR; 2126 2127 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 2128 /* 2129 * Page table corrupted: show pte and kill process. 2130 */ 2131 print_bad_pte(vma, orig_pte, address); 2132 return VM_FAULT_OOM; 2133 } 2134 /* We can then assume vm->vm_ops && vma->vm_ops->populate */ 2135 2136 pgoff = pte_to_pgoff(orig_pte); 2137 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, 2138 vma->vm_page_prot, pgoff, 0); 2139 if (err == -ENOMEM) 2140 return VM_FAULT_OOM; 2141 if (err) 2142 return VM_FAULT_SIGBUS; 2143 return VM_FAULT_MAJOR; 2144} 2145 2146/* 2147 * These routines also need to handle stuff like marking pages dirty 2148 * and/or accessed for architectures that don't do it in hardware (most 2149 * RISC architectures). The early dirtying is also good on the i386. 2150 * 2151 * There is also a hook called "update_mmu_cache()" that architectures 2152 * with external mmu caches can use to update those (ie the Sparc or 2153 * PowerPC hashed page tables that act as extended TLBs). 2154 * 2155 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2156 * but allow concurrent faults), and pte mapped but not yet locked. 2157 * We return with mmap_sem still held, but pte unmapped and unlocked. 2158 */ 2159static inline int handle_pte_fault(struct mm_struct *mm, 2160 struct vm_area_struct *vma, unsigned long address, 2161 pte_t *pte, pmd_t *pmd, int write_access) 2162{ 2163 pte_t entry; 2164 pte_t old_entry; 2165 spinlock_t *ptl; 2166 2167 old_entry = entry = *pte; 2168 if (!pte_present(entry)) { 2169 if (pte_none(entry)) { 2170 if (!vma->vm_ops || !vma->vm_ops->nopage) 2171 return do_anonymous_page(mm, vma, address, 2172 pte, pmd, write_access); 2173 return do_no_page(mm, vma, address, 2174 pte, pmd, write_access); 2175 } 2176 if (pte_file(entry)) 2177 return do_file_page(mm, vma, address, 2178 pte, pmd, write_access, entry); 2179 return do_swap_page(mm, vma, address, 2180 pte, pmd, write_access, entry); 2181 } 2182 2183 ptl = pte_lockptr(mm, pmd); 2184 spin_lock(ptl); 2185 if (unlikely(!pte_same(*pte, entry))) 2186 goto unlock; 2187 if (write_access) { 2188 if (!pte_write(entry)) 2189 return do_wp_page(mm, vma, address, 2190 pte, pmd, ptl, entry); 2191 entry = pte_mkdirty(entry); 2192 } 2193 entry = pte_mkyoung(entry); 2194 if (!pte_same(old_entry, entry)) { 2195 ptep_set_access_flags(vma, address, pte, entry, write_access); 2196 update_mmu_cache(vma, address, entry); 2197 lazy_mmu_prot_update(entry); 2198 } else { 2199 /* 2200 * This is needed only for protection faults but the arch code 2201 * is not yet telling us if this is a protection fault or not. 2202 * This still avoids useless tlb flushes for .text page faults 2203 * with threads. 2204 */ 2205 if (write_access) 2206 flush_tlb_page(vma, address); 2207 } 2208unlock: 2209 pte_unmap_unlock(pte, ptl); 2210 return VM_FAULT_MINOR; 2211} 2212 2213/* 2214 * By the time we get here, we already hold the mm semaphore 2215 */ 2216int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2217 unsigned long address, int write_access) 2218{ 2219 pgd_t *pgd; 2220 pud_t *pud; 2221 pmd_t *pmd; 2222 pte_t *pte; 2223 2224 __set_current_state(TASK_RUNNING); 2225 2226 inc_page_state(pgfault); 2227 2228 if (unlikely(is_vm_hugetlb_page(vma))) 2229 return hugetlb_fault(mm, vma, address, write_access); 2230 2231 pgd = pgd_offset(mm, address); 2232 pud = pud_alloc(mm, pgd, address); 2233 if (!pud) 2234 return VM_FAULT_OOM; 2235 pmd = pmd_alloc(mm, pud, address); 2236 if (!pmd) 2237 return VM_FAULT_OOM; 2238 pte = pte_alloc_map(mm, pmd, address); 2239 if (!pte) 2240 return VM_FAULT_OOM; 2241 2242 return handle_pte_fault(mm, vma, address, pte, pmd, write_access); 2243} 2244 2245#ifndef __PAGETABLE_PUD_FOLDED 2246/* 2247 * Allocate page upper directory. 2248 * We've already handled the fast-path in-line. 2249 */ 2250int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2251{ 2252 pud_t *new = pud_alloc_one(mm, address); 2253 if (!new) 2254 return -ENOMEM; 2255 2256 spin_lock(&mm->page_table_lock); 2257 if (pgd_present(*pgd)) /* Another has populated it */ 2258 pud_free(new); 2259 else 2260 pgd_populate(mm, pgd, new); 2261 spin_unlock(&mm->page_table_lock); 2262 return 0; 2263} 2264#else 2265/* Workaround for gcc 2.96 */ 2266int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2267{ 2268 return 0; 2269} 2270#endif /* __PAGETABLE_PUD_FOLDED */ 2271 2272#ifndef __PAGETABLE_PMD_FOLDED 2273/* 2274 * Allocate page middle directory. 2275 * We've already handled the fast-path in-line. 2276 */ 2277int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2278{ 2279 pmd_t *new = pmd_alloc_one(mm, address); 2280 if (!new) 2281 return -ENOMEM; 2282 2283 spin_lock(&mm->page_table_lock); 2284#ifndef __ARCH_HAS_4LEVEL_HACK 2285 if (pud_present(*pud)) /* Another has populated it */ 2286 pmd_free(new); 2287 else 2288 pud_populate(mm, pud, new); 2289#else 2290 if (pgd_present(*pud)) /* Another has populated it */ 2291 pmd_free(new); 2292 else 2293 pgd_populate(mm, pud, new); 2294#endif /* __ARCH_HAS_4LEVEL_HACK */ 2295 spin_unlock(&mm->page_table_lock); 2296 return 0; 2297} 2298#else 2299/* Workaround for gcc 2.96 */ 2300int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2301{ 2302 return 0; 2303} 2304#endif /* __PAGETABLE_PMD_FOLDED */ 2305 2306int make_pages_present(unsigned long addr, unsigned long end) 2307{ 2308 int ret, len, write; 2309 struct vm_area_struct * vma; 2310 2311 vma = find_vma(current->mm, addr); 2312 if (!vma) 2313 return -1; 2314 write = (vma->vm_flags & VM_WRITE) != 0; 2315 if (addr >= end) 2316 BUG(); 2317 if (end > vma->vm_end) 2318 BUG(); 2319 len = (end+PAGE_SIZE-1)/PAGE_SIZE-addr/PAGE_SIZE; 2320 ret = get_user_pages(current, current->mm, addr, 2321 len, write, 0, NULL, NULL); 2322 if (ret < 0) 2323 return ret; 2324 return ret == len ? 0 : -1; 2325} 2326 2327/* 2328 * Map a vmalloc()-space virtual address to the physical page. 2329 */ 2330struct page * vmalloc_to_page(void * vmalloc_addr) 2331{ 2332 unsigned long addr = (unsigned long) vmalloc_addr; 2333 struct page *page = NULL; 2334 pgd_t *pgd = pgd_offset_k(addr); 2335 pud_t *pud; 2336 pmd_t *pmd; 2337 pte_t *ptep, pte; 2338 2339 if (!pgd_none(*pgd)) { 2340 pud = pud_offset(pgd, addr); 2341 if (!pud_none(*pud)) { 2342 pmd = pmd_offset(pud, addr); 2343 if (!pmd_none(*pmd)) { 2344 ptep = pte_offset_map(pmd, addr); 2345 pte = *ptep; 2346 if (pte_present(pte)) 2347 page = pte_page(pte); 2348 pte_unmap(ptep); 2349 } 2350 } 2351 } 2352 return page; 2353} 2354 2355EXPORT_SYMBOL(vmalloc_to_page); 2356 2357/* 2358 * Map a vmalloc()-space virtual address to the physical page frame number. 2359 */ 2360unsigned long vmalloc_to_pfn(void * vmalloc_addr) 2361{ 2362 return page_to_pfn(vmalloc_to_page(vmalloc_addr)); 2363} 2364 2365EXPORT_SYMBOL(vmalloc_to_pfn); 2366 2367#if !defined(__HAVE_ARCH_GATE_AREA) 2368 2369#if defined(AT_SYSINFO_EHDR) 2370static struct vm_area_struct gate_vma; 2371 2372static int __init gate_vma_init(void) 2373{ 2374 gate_vma.vm_mm = NULL; 2375 gate_vma.vm_start = FIXADDR_USER_START; 2376 gate_vma.vm_end = FIXADDR_USER_END; 2377 gate_vma.vm_page_prot = PAGE_READONLY; 2378 gate_vma.vm_flags = 0; 2379 return 0; 2380} 2381__initcall(gate_vma_init); 2382#endif 2383 2384struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 2385{ 2386#ifdef AT_SYSINFO_EHDR 2387 return &gate_vma; 2388#else 2389 return NULL; 2390#endif 2391} 2392 2393int in_gate_area_no_task(unsigned long addr) 2394{ 2395#ifdef AT_SYSINFO_EHDR 2396 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 2397 return 1; 2398#endif 2399 return 0; 2400} 2401 2402#endif /* __HAVE_ARCH_GATE_AREA */ 2403