memory.c revision 54cb8821de07f2ffcd28c380ce9b93d5784b40d7
1/* 2 * linux/mm/memory.c 3 * 4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 5 */ 6 7/* 8 * demand-loading started 01.12.91 - seems it is high on the list of 9 * things wanted, and it should be easy to implement. - Linus 10 */ 11 12/* 13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared 14 * pages started 02.12.91, seems to work. - Linus. 15 * 16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it 17 * would have taken more than the 6M I have free, but it worked well as 18 * far as I could see. 19 * 20 * Also corrected some "invalidate()"s - I wasn't doing enough of them. 21 */ 22 23/* 24 * Real VM (paging to/from disk) started 18.12.91. Much more work and 25 * thought has to go into this. Oh, well.. 26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. 27 * Found it. Everything seems to work now. 28 * 20.12.91 - Ok, making the swap-device changeable like the root. 29 */ 30 31/* 32 * 05.04.94 - Multi-page memory management added for v1.1. 33 * Idea by Alex Bligh (alex@cconcepts.co.uk) 34 * 35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG 36 * (Gerhard.Wichert@pdb.siemens.de) 37 * 38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) 39 */ 40 41#include <linux/kernel_stat.h> 42#include <linux/mm.h> 43#include <linux/hugetlb.h> 44#include <linux/mman.h> 45#include <linux/swap.h> 46#include <linux/highmem.h> 47#include <linux/pagemap.h> 48#include <linux/rmap.h> 49#include <linux/module.h> 50#include <linux/delayacct.h> 51#include <linux/init.h> 52#include <linux/writeback.h> 53 54#include <asm/pgalloc.h> 55#include <asm/uaccess.h> 56#include <asm/tlb.h> 57#include <asm/tlbflush.h> 58#include <asm/pgtable.h> 59 60#include <linux/swapops.h> 61#include <linux/elf.h> 62 63#ifndef CONFIG_NEED_MULTIPLE_NODES 64/* use the per-pgdat data instead for discontigmem - mbligh */ 65unsigned long max_mapnr; 66struct page *mem_map; 67 68EXPORT_SYMBOL(max_mapnr); 69EXPORT_SYMBOL(mem_map); 70#endif 71 72unsigned long num_physpages; 73/* 74 * A number of key systems in x86 including ioremap() rely on the assumption 75 * that high_memory defines the upper bound on direct map memory, then end 76 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 77 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 78 * and ZONE_HIGHMEM. 79 */ 80void * high_memory; 81 82EXPORT_SYMBOL(num_physpages); 83EXPORT_SYMBOL(high_memory); 84 85int randomize_va_space __read_mostly = 1; 86 87static int __init disable_randmaps(char *s) 88{ 89 randomize_va_space = 0; 90 return 1; 91} 92__setup("norandmaps", disable_randmaps); 93 94 95/* 96 * If a p?d_bad entry is found while walking page tables, report 97 * the error, before resetting entry to p?d_none. Usually (but 98 * very seldom) called out from the p?d_none_or_clear_bad macros. 99 */ 100 101void pgd_clear_bad(pgd_t *pgd) 102{ 103 pgd_ERROR(*pgd); 104 pgd_clear(pgd); 105} 106 107void pud_clear_bad(pud_t *pud) 108{ 109 pud_ERROR(*pud); 110 pud_clear(pud); 111} 112 113void pmd_clear_bad(pmd_t *pmd) 114{ 115 pmd_ERROR(*pmd); 116 pmd_clear(pmd); 117} 118 119/* 120 * Note: this doesn't free the actual pages themselves. That 121 * has been handled earlier when unmapping all the memory regions. 122 */ 123static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd) 124{ 125 struct page *page = pmd_page(*pmd); 126 pmd_clear(pmd); 127 pte_lock_deinit(page); 128 pte_free_tlb(tlb, page); 129 dec_zone_page_state(page, NR_PAGETABLE); 130 tlb->mm->nr_ptes--; 131} 132 133static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 134 unsigned long addr, unsigned long end, 135 unsigned long floor, unsigned long ceiling) 136{ 137 pmd_t *pmd; 138 unsigned long next; 139 unsigned long start; 140 141 start = addr; 142 pmd = pmd_offset(pud, addr); 143 do { 144 next = pmd_addr_end(addr, end); 145 if (pmd_none_or_clear_bad(pmd)) 146 continue; 147 free_pte_range(tlb, pmd); 148 } while (pmd++, addr = next, addr != end); 149 150 start &= PUD_MASK; 151 if (start < floor) 152 return; 153 if (ceiling) { 154 ceiling &= PUD_MASK; 155 if (!ceiling) 156 return; 157 } 158 if (end - 1 > ceiling - 1) 159 return; 160 161 pmd = pmd_offset(pud, start); 162 pud_clear(pud); 163 pmd_free_tlb(tlb, pmd); 164} 165 166static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 167 unsigned long addr, unsigned long end, 168 unsigned long floor, unsigned long ceiling) 169{ 170 pud_t *pud; 171 unsigned long next; 172 unsigned long start; 173 174 start = addr; 175 pud = pud_offset(pgd, addr); 176 do { 177 next = pud_addr_end(addr, end); 178 if (pud_none_or_clear_bad(pud)) 179 continue; 180 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 181 } while (pud++, addr = next, addr != end); 182 183 start &= PGDIR_MASK; 184 if (start < floor) 185 return; 186 if (ceiling) { 187 ceiling &= PGDIR_MASK; 188 if (!ceiling) 189 return; 190 } 191 if (end - 1 > ceiling - 1) 192 return; 193 194 pud = pud_offset(pgd, start); 195 pgd_clear(pgd); 196 pud_free_tlb(tlb, pud); 197} 198 199/* 200 * This function frees user-level page tables of a process. 201 * 202 * Must be called with pagetable lock held. 203 */ 204void free_pgd_range(struct mmu_gather **tlb, 205 unsigned long addr, unsigned long end, 206 unsigned long floor, unsigned long ceiling) 207{ 208 pgd_t *pgd; 209 unsigned long next; 210 unsigned long start; 211 212 /* 213 * The next few lines have given us lots of grief... 214 * 215 * Why are we testing PMD* at this top level? Because often 216 * there will be no work to do at all, and we'd prefer not to 217 * go all the way down to the bottom just to discover that. 218 * 219 * Why all these "- 1"s? Because 0 represents both the bottom 220 * of the address space and the top of it (using -1 for the 221 * top wouldn't help much: the masks would do the wrong thing). 222 * The rule is that addr 0 and floor 0 refer to the bottom of 223 * the address space, but end 0 and ceiling 0 refer to the top 224 * Comparisons need to use "end - 1" and "ceiling - 1" (though 225 * that end 0 case should be mythical). 226 * 227 * Wherever addr is brought up or ceiling brought down, we must 228 * be careful to reject "the opposite 0" before it confuses the 229 * subsequent tests. But what about where end is brought down 230 * by PMD_SIZE below? no, end can't go down to 0 there. 231 * 232 * Whereas we round start (addr) and ceiling down, by different 233 * masks at different levels, in order to test whether a table 234 * now has no other vmas using it, so can be freed, we don't 235 * bother to round floor or end up - the tests don't need that. 236 */ 237 238 addr &= PMD_MASK; 239 if (addr < floor) { 240 addr += PMD_SIZE; 241 if (!addr) 242 return; 243 } 244 if (ceiling) { 245 ceiling &= PMD_MASK; 246 if (!ceiling) 247 return; 248 } 249 if (end - 1 > ceiling - 1) 250 end -= PMD_SIZE; 251 if (addr > end - 1) 252 return; 253 254 start = addr; 255 pgd = pgd_offset((*tlb)->mm, addr); 256 do { 257 next = pgd_addr_end(addr, end); 258 if (pgd_none_or_clear_bad(pgd)) 259 continue; 260 free_pud_range(*tlb, pgd, addr, next, floor, ceiling); 261 } while (pgd++, addr = next, addr != end); 262 263 if (!(*tlb)->fullmm) 264 flush_tlb_pgtables((*tlb)->mm, start, end); 265} 266 267void free_pgtables(struct mmu_gather **tlb, struct vm_area_struct *vma, 268 unsigned long floor, unsigned long ceiling) 269{ 270 while (vma) { 271 struct vm_area_struct *next = vma->vm_next; 272 unsigned long addr = vma->vm_start; 273 274 /* 275 * Hide vma from rmap and vmtruncate before freeing pgtables 276 */ 277 anon_vma_unlink(vma); 278 unlink_file_vma(vma); 279 280 if (is_vm_hugetlb_page(vma)) { 281 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 282 floor, next? next->vm_start: ceiling); 283 } else { 284 /* 285 * Optimization: gather nearby vmas into one call down 286 */ 287 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 288 && !is_vm_hugetlb_page(next)) { 289 vma = next; 290 next = vma->vm_next; 291 anon_vma_unlink(vma); 292 unlink_file_vma(vma); 293 } 294 free_pgd_range(tlb, addr, vma->vm_end, 295 floor, next? next->vm_start: ceiling); 296 } 297 vma = next; 298 } 299} 300 301int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 302{ 303 struct page *new = pte_alloc_one(mm, address); 304 if (!new) 305 return -ENOMEM; 306 307 pte_lock_init(new); 308 spin_lock(&mm->page_table_lock); 309 if (pmd_present(*pmd)) { /* Another has populated it */ 310 pte_lock_deinit(new); 311 pte_free(new); 312 } else { 313 mm->nr_ptes++; 314 inc_zone_page_state(new, NR_PAGETABLE); 315 pmd_populate(mm, pmd, new); 316 } 317 spin_unlock(&mm->page_table_lock); 318 return 0; 319} 320 321int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 322{ 323 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 324 if (!new) 325 return -ENOMEM; 326 327 spin_lock(&init_mm.page_table_lock); 328 if (pmd_present(*pmd)) /* Another has populated it */ 329 pte_free_kernel(new); 330 else 331 pmd_populate_kernel(&init_mm, pmd, new); 332 spin_unlock(&init_mm.page_table_lock); 333 return 0; 334} 335 336static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) 337{ 338 if (file_rss) 339 add_mm_counter(mm, file_rss, file_rss); 340 if (anon_rss) 341 add_mm_counter(mm, anon_rss, anon_rss); 342} 343 344/* 345 * This function is called to print an error when a bad pte 346 * is found. For example, we might have a PFN-mapped pte in 347 * a region that doesn't allow it. 348 * 349 * The calling function must still handle the error. 350 */ 351void print_bad_pte(struct vm_area_struct *vma, pte_t pte, unsigned long vaddr) 352{ 353 printk(KERN_ERR "Bad pte = %08llx, process = %s, " 354 "vm_flags = %lx, vaddr = %lx\n", 355 (long long)pte_val(pte), 356 (vma->vm_mm == current->mm ? current->comm : "???"), 357 vma->vm_flags, vaddr); 358 dump_stack(); 359} 360 361static inline int is_cow_mapping(unsigned int flags) 362{ 363 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 364} 365 366/* 367 * This function gets the "struct page" associated with a pte. 368 * 369 * NOTE! Some mappings do not have "struct pages". A raw PFN mapping 370 * will have each page table entry just pointing to a raw page frame 371 * number, and as far as the VM layer is concerned, those do not have 372 * pages associated with them - even if the PFN might point to memory 373 * that otherwise is perfectly fine and has a "struct page". 374 * 375 * The way we recognize those mappings is through the rules set up 376 * by "remap_pfn_range()": the vma will have the VM_PFNMAP bit set, 377 * and the vm_pgoff will point to the first PFN mapped: thus every 378 * page that is a raw mapping will always honor the rule 379 * 380 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 381 * 382 * and if that isn't true, the page has been COW'ed (in which case it 383 * _does_ have a "struct page" associated with it even if it is in a 384 * VM_PFNMAP range). 385 */ 386struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, pte_t pte) 387{ 388 unsigned long pfn = pte_pfn(pte); 389 390 if (unlikely(vma->vm_flags & VM_PFNMAP)) { 391 unsigned long off = (addr - vma->vm_start) >> PAGE_SHIFT; 392 if (pfn == vma->vm_pgoff + off) 393 return NULL; 394 if (!is_cow_mapping(vma->vm_flags)) 395 return NULL; 396 } 397 398 /* 399 * Add some anal sanity checks for now. Eventually, 400 * we should just do "return pfn_to_page(pfn)", but 401 * in the meantime we check that we get a valid pfn, 402 * and that the resulting page looks ok. 403 */ 404 if (unlikely(!pfn_valid(pfn))) { 405 print_bad_pte(vma, pte, addr); 406 return NULL; 407 } 408 409 /* 410 * NOTE! We still have PageReserved() pages in the page 411 * tables. 412 * 413 * The PAGE_ZERO() pages and various VDSO mappings can 414 * cause them to exist. 415 */ 416 return pfn_to_page(pfn); 417} 418 419/* 420 * copy one vm_area from one task to the other. Assumes the page tables 421 * already present in the new task to be cleared in the whole range 422 * covered by this vma. 423 */ 424 425static inline void 426copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 427 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 428 unsigned long addr, int *rss) 429{ 430 unsigned long vm_flags = vma->vm_flags; 431 pte_t pte = *src_pte; 432 struct page *page; 433 434 /* pte contains position in swap or file, so copy. */ 435 if (unlikely(!pte_present(pte))) { 436 if (!pte_file(pte)) { 437 swp_entry_t entry = pte_to_swp_entry(pte); 438 439 swap_duplicate(entry); 440 /* make sure dst_mm is on swapoff's mmlist. */ 441 if (unlikely(list_empty(&dst_mm->mmlist))) { 442 spin_lock(&mmlist_lock); 443 if (list_empty(&dst_mm->mmlist)) 444 list_add(&dst_mm->mmlist, 445 &src_mm->mmlist); 446 spin_unlock(&mmlist_lock); 447 } 448 if (is_write_migration_entry(entry) && 449 is_cow_mapping(vm_flags)) { 450 /* 451 * COW mappings require pages in both parent 452 * and child to be set to read. 453 */ 454 make_migration_entry_read(&entry); 455 pte = swp_entry_to_pte(entry); 456 set_pte_at(src_mm, addr, src_pte, pte); 457 } 458 } 459 goto out_set_pte; 460 } 461 462 /* 463 * If it's a COW mapping, write protect it both 464 * in the parent and the child 465 */ 466 if (is_cow_mapping(vm_flags)) { 467 ptep_set_wrprotect(src_mm, addr, src_pte); 468 pte = pte_wrprotect(pte); 469 } 470 471 /* 472 * If it's a shared mapping, mark it clean in 473 * the child 474 */ 475 if (vm_flags & VM_SHARED) 476 pte = pte_mkclean(pte); 477 pte = pte_mkold(pte); 478 479 page = vm_normal_page(vma, addr, pte); 480 if (page) { 481 get_page(page); 482 page_dup_rmap(page, vma, addr); 483 rss[!!PageAnon(page)]++; 484 } 485 486out_set_pte: 487 set_pte_at(dst_mm, addr, dst_pte, pte); 488} 489 490static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 491 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 492 unsigned long addr, unsigned long end) 493{ 494 pte_t *src_pte, *dst_pte; 495 spinlock_t *src_ptl, *dst_ptl; 496 int progress = 0; 497 int rss[2]; 498 499again: 500 rss[1] = rss[0] = 0; 501 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 502 if (!dst_pte) 503 return -ENOMEM; 504 src_pte = pte_offset_map_nested(src_pmd, addr); 505 src_ptl = pte_lockptr(src_mm, src_pmd); 506 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 507 arch_enter_lazy_mmu_mode(); 508 509 do { 510 /* 511 * We are holding two locks at this point - either of them 512 * could generate latencies in another task on another CPU. 513 */ 514 if (progress >= 32) { 515 progress = 0; 516 if (need_resched() || 517 need_lockbreak(src_ptl) || 518 need_lockbreak(dst_ptl)) 519 break; 520 } 521 if (pte_none(*src_pte)) { 522 progress++; 523 continue; 524 } 525 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 526 progress += 8; 527 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 528 529 arch_leave_lazy_mmu_mode(); 530 spin_unlock(src_ptl); 531 pte_unmap_nested(src_pte - 1); 532 add_mm_rss(dst_mm, rss[0], rss[1]); 533 pte_unmap_unlock(dst_pte - 1, dst_ptl); 534 cond_resched(); 535 if (addr != end) 536 goto again; 537 return 0; 538} 539 540static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 541 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 542 unsigned long addr, unsigned long end) 543{ 544 pmd_t *src_pmd, *dst_pmd; 545 unsigned long next; 546 547 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 548 if (!dst_pmd) 549 return -ENOMEM; 550 src_pmd = pmd_offset(src_pud, addr); 551 do { 552 next = pmd_addr_end(addr, end); 553 if (pmd_none_or_clear_bad(src_pmd)) 554 continue; 555 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 556 vma, addr, next)) 557 return -ENOMEM; 558 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 559 return 0; 560} 561 562static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 563 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 564 unsigned long addr, unsigned long end) 565{ 566 pud_t *src_pud, *dst_pud; 567 unsigned long next; 568 569 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 570 if (!dst_pud) 571 return -ENOMEM; 572 src_pud = pud_offset(src_pgd, addr); 573 do { 574 next = pud_addr_end(addr, end); 575 if (pud_none_or_clear_bad(src_pud)) 576 continue; 577 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 578 vma, addr, next)) 579 return -ENOMEM; 580 } while (dst_pud++, src_pud++, addr = next, addr != end); 581 return 0; 582} 583 584int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 585 struct vm_area_struct *vma) 586{ 587 pgd_t *src_pgd, *dst_pgd; 588 unsigned long next; 589 unsigned long addr = vma->vm_start; 590 unsigned long end = vma->vm_end; 591 592 /* 593 * Don't copy ptes where a page fault will fill them correctly. 594 * Fork becomes much lighter when there are big shared or private 595 * readonly mappings. The tradeoff is that copy_page_range is more 596 * efficient than faulting. 597 */ 598 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 599 if (!vma->anon_vma) 600 return 0; 601 } 602 603 if (is_vm_hugetlb_page(vma)) 604 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 605 606 dst_pgd = pgd_offset(dst_mm, addr); 607 src_pgd = pgd_offset(src_mm, addr); 608 do { 609 next = pgd_addr_end(addr, end); 610 if (pgd_none_or_clear_bad(src_pgd)) 611 continue; 612 if (copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 613 vma, addr, next)) 614 return -ENOMEM; 615 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 616 return 0; 617} 618 619static unsigned long zap_pte_range(struct mmu_gather *tlb, 620 struct vm_area_struct *vma, pmd_t *pmd, 621 unsigned long addr, unsigned long end, 622 long *zap_work, struct zap_details *details) 623{ 624 struct mm_struct *mm = tlb->mm; 625 pte_t *pte; 626 spinlock_t *ptl; 627 int file_rss = 0; 628 int anon_rss = 0; 629 630 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 631 arch_enter_lazy_mmu_mode(); 632 do { 633 pte_t ptent = *pte; 634 if (pte_none(ptent)) { 635 (*zap_work)--; 636 continue; 637 } 638 639 (*zap_work) -= PAGE_SIZE; 640 641 if (pte_present(ptent)) { 642 struct page *page; 643 644 page = vm_normal_page(vma, addr, ptent); 645 if (unlikely(details) && page) { 646 /* 647 * unmap_shared_mapping_pages() wants to 648 * invalidate cache without truncating: 649 * unmap shared but keep private pages. 650 */ 651 if (details->check_mapping && 652 details->check_mapping != page->mapping) 653 continue; 654 /* 655 * Each page->index must be checked when 656 * invalidating or truncating nonlinear. 657 */ 658 if (details->nonlinear_vma && 659 (page->index < details->first_index || 660 page->index > details->last_index)) 661 continue; 662 } 663 ptent = ptep_get_and_clear_full(mm, addr, pte, 664 tlb->fullmm); 665 tlb_remove_tlb_entry(tlb, pte, addr); 666 if (unlikely(!page)) 667 continue; 668 if (unlikely(details) && details->nonlinear_vma 669 && linear_page_index(details->nonlinear_vma, 670 addr) != page->index) 671 set_pte_at(mm, addr, pte, 672 pgoff_to_pte(page->index)); 673 if (PageAnon(page)) 674 anon_rss--; 675 else { 676 if (pte_dirty(ptent)) 677 set_page_dirty(page); 678 if (pte_young(ptent)) 679 SetPageReferenced(page); 680 file_rss--; 681 } 682 page_remove_rmap(page, vma); 683 tlb_remove_page(tlb, page); 684 continue; 685 } 686 /* 687 * If details->check_mapping, we leave swap entries; 688 * if details->nonlinear_vma, we leave file entries. 689 */ 690 if (unlikely(details)) 691 continue; 692 if (!pte_file(ptent)) 693 free_swap_and_cache(pte_to_swp_entry(ptent)); 694 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 695 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 696 697 add_mm_rss(mm, file_rss, anon_rss); 698 arch_leave_lazy_mmu_mode(); 699 pte_unmap_unlock(pte - 1, ptl); 700 701 return addr; 702} 703 704static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 705 struct vm_area_struct *vma, pud_t *pud, 706 unsigned long addr, unsigned long end, 707 long *zap_work, struct zap_details *details) 708{ 709 pmd_t *pmd; 710 unsigned long next; 711 712 pmd = pmd_offset(pud, addr); 713 do { 714 next = pmd_addr_end(addr, end); 715 if (pmd_none_or_clear_bad(pmd)) { 716 (*zap_work)--; 717 continue; 718 } 719 next = zap_pte_range(tlb, vma, pmd, addr, next, 720 zap_work, details); 721 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 722 723 return addr; 724} 725 726static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 727 struct vm_area_struct *vma, pgd_t *pgd, 728 unsigned long addr, unsigned long end, 729 long *zap_work, struct zap_details *details) 730{ 731 pud_t *pud; 732 unsigned long next; 733 734 pud = pud_offset(pgd, addr); 735 do { 736 next = pud_addr_end(addr, end); 737 if (pud_none_or_clear_bad(pud)) { 738 (*zap_work)--; 739 continue; 740 } 741 next = zap_pmd_range(tlb, vma, pud, addr, next, 742 zap_work, details); 743 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 744 745 return addr; 746} 747 748static unsigned long unmap_page_range(struct mmu_gather *tlb, 749 struct vm_area_struct *vma, 750 unsigned long addr, unsigned long end, 751 long *zap_work, struct zap_details *details) 752{ 753 pgd_t *pgd; 754 unsigned long next; 755 756 if (details && !details->check_mapping && !details->nonlinear_vma) 757 details = NULL; 758 759 BUG_ON(addr >= end); 760 tlb_start_vma(tlb, vma); 761 pgd = pgd_offset(vma->vm_mm, addr); 762 do { 763 next = pgd_addr_end(addr, end); 764 if (pgd_none_or_clear_bad(pgd)) { 765 (*zap_work)--; 766 continue; 767 } 768 next = zap_pud_range(tlb, vma, pgd, addr, next, 769 zap_work, details); 770 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 771 tlb_end_vma(tlb, vma); 772 773 return addr; 774} 775 776#ifdef CONFIG_PREEMPT 777# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 778#else 779/* No preempt: go for improved straight-line efficiency */ 780# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 781#endif 782 783/** 784 * unmap_vmas - unmap a range of memory covered by a list of vma's 785 * @tlbp: address of the caller's struct mmu_gather 786 * @vma: the starting vma 787 * @start_addr: virtual address at which to start unmapping 788 * @end_addr: virtual address at which to end unmapping 789 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 790 * @details: details of nonlinear truncation or shared cache invalidation 791 * 792 * Returns the end address of the unmapping (restart addr if interrupted). 793 * 794 * Unmap all pages in the vma list. 795 * 796 * We aim to not hold locks for too long (for scheduling latency reasons). 797 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 798 * return the ending mmu_gather to the caller. 799 * 800 * Only addresses between `start' and `end' will be unmapped. 801 * 802 * The VMA list must be sorted in ascending virtual address order. 803 * 804 * unmap_vmas() assumes that the caller will flush the whole unmapped address 805 * range after unmap_vmas() returns. So the only responsibility here is to 806 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 807 * drops the lock and schedules. 808 */ 809unsigned long unmap_vmas(struct mmu_gather **tlbp, 810 struct vm_area_struct *vma, unsigned long start_addr, 811 unsigned long end_addr, unsigned long *nr_accounted, 812 struct zap_details *details) 813{ 814 long zap_work = ZAP_BLOCK_SIZE; 815 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 816 int tlb_start_valid = 0; 817 unsigned long start = start_addr; 818 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 819 int fullmm = (*tlbp)->fullmm; 820 821 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 822 unsigned long end; 823 824 start = max(vma->vm_start, start_addr); 825 if (start >= vma->vm_end) 826 continue; 827 end = min(vma->vm_end, end_addr); 828 if (end <= vma->vm_start) 829 continue; 830 831 if (vma->vm_flags & VM_ACCOUNT) 832 *nr_accounted += (end - start) >> PAGE_SHIFT; 833 834 while (start != end) { 835 if (!tlb_start_valid) { 836 tlb_start = start; 837 tlb_start_valid = 1; 838 } 839 840 if (unlikely(is_vm_hugetlb_page(vma))) { 841 unmap_hugepage_range(vma, start, end); 842 zap_work -= (end - start) / 843 (HPAGE_SIZE / PAGE_SIZE); 844 start = end; 845 } else 846 start = unmap_page_range(*tlbp, vma, 847 start, end, &zap_work, details); 848 849 if (zap_work > 0) { 850 BUG_ON(start != end); 851 break; 852 } 853 854 tlb_finish_mmu(*tlbp, tlb_start, start); 855 856 if (need_resched() || 857 (i_mmap_lock && need_lockbreak(i_mmap_lock))) { 858 if (i_mmap_lock) { 859 *tlbp = NULL; 860 goto out; 861 } 862 cond_resched(); 863 } 864 865 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 866 tlb_start_valid = 0; 867 zap_work = ZAP_BLOCK_SIZE; 868 } 869 } 870out: 871 return start; /* which is now the end (or restart) address */ 872} 873 874/** 875 * zap_page_range - remove user pages in a given range 876 * @vma: vm_area_struct holding the applicable pages 877 * @address: starting address of pages to zap 878 * @size: number of bytes to zap 879 * @details: details of nonlinear truncation or shared cache invalidation 880 */ 881unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 882 unsigned long size, struct zap_details *details) 883{ 884 struct mm_struct *mm = vma->vm_mm; 885 struct mmu_gather *tlb; 886 unsigned long end = address + size; 887 unsigned long nr_accounted = 0; 888 889 lru_add_drain(); 890 tlb = tlb_gather_mmu(mm, 0); 891 update_hiwater_rss(mm); 892 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 893 if (tlb) 894 tlb_finish_mmu(tlb, address, end); 895 return end; 896} 897 898/* 899 * Do a quick page-table lookup for a single page. 900 */ 901struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 902 unsigned int flags) 903{ 904 pgd_t *pgd; 905 pud_t *pud; 906 pmd_t *pmd; 907 pte_t *ptep, pte; 908 spinlock_t *ptl; 909 struct page *page; 910 struct mm_struct *mm = vma->vm_mm; 911 912 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 913 if (!IS_ERR(page)) { 914 BUG_ON(flags & FOLL_GET); 915 goto out; 916 } 917 918 page = NULL; 919 pgd = pgd_offset(mm, address); 920 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 921 goto no_page_table; 922 923 pud = pud_offset(pgd, address); 924 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 925 goto no_page_table; 926 927 pmd = pmd_offset(pud, address); 928 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 929 goto no_page_table; 930 931 if (pmd_huge(*pmd)) { 932 BUG_ON(flags & FOLL_GET); 933 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 934 goto out; 935 } 936 937 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 938 if (!ptep) 939 goto out; 940 941 pte = *ptep; 942 if (!pte_present(pte)) 943 goto unlock; 944 if ((flags & FOLL_WRITE) && !pte_write(pte)) 945 goto unlock; 946 page = vm_normal_page(vma, address, pte); 947 if (unlikely(!page)) 948 goto unlock; 949 950 if (flags & FOLL_GET) 951 get_page(page); 952 if (flags & FOLL_TOUCH) { 953 if ((flags & FOLL_WRITE) && 954 !pte_dirty(pte) && !PageDirty(page)) 955 set_page_dirty(page); 956 mark_page_accessed(page); 957 } 958unlock: 959 pte_unmap_unlock(ptep, ptl); 960out: 961 return page; 962 963no_page_table: 964 /* 965 * When core dumping an enormous anonymous area that nobody 966 * has touched so far, we don't want to allocate page tables. 967 */ 968 if (flags & FOLL_ANON) { 969 page = ZERO_PAGE(address); 970 if (flags & FOLL_GET) 971 get_page(page); 972 BUG_ON(flags & FOLL_WRITE); 973 } 974 return page; 975} 976 977int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 978 unsigned long start, int len, int write, int force, 979 struct page **pages, struct vm_area_struct **vmas) 980{ 981 int i; 982 unsigned int vm_flags; 983 984 /* 985 * Require read or write permissions. 986 * If 'force' is set, we only require the "MAY" flags. 987 */ 988 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 989 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 990 i = 0; 991 992 do { 993 struct vm_area_struct *vma; 994 unsigned int foll_flags; 995 996 vma = find_extend_vma(mm, start); 997 if (!vma && in_gate_area(tsk, start)) { 998 unsigned long pg = start & PAGE_MASK; 999 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 1000 pgd_t *pgd; 1001 pud_t *pud; 1002 pmd_t *pmd; 1003 pte_t *pte; 1004 if (write) /* user gate pages are read-only */ 1005 return i ? : -EFAULT; 1006 if (pg > TASK_SIZE) 1007 pgd = pgd_offset_k(pg); 1008 else 1009 pgd = pgd_offset_gate(mm, pg); 1010 BUG_ON(pgd_none(*pgd)); 1011 pud = pud_offset(pgd, pg); 1012 BUG_ON(pud_none(*pud)); 1013 pmd = pmd_offset(pud, pg); 1014 if (pmd_none(*pmd)) 1015 return i ? : -EFAULT; 1016 pte = pte_offset_map(pmd, pg); 1017 if (pte_none(*pte)) { 1018 pte_unmap(pte); 1019 return i ? : -EFAULT; 1020 } 1021 if (pages) { 1022 struct page *page = vm_normal_page(gate_vma, start, *pte); 1023 pages[i] = page; 1024 if (page) 1025 get_page(page); 1026 } 1027 pte_unmap(pte); 1028 if (vmas) 1029 vmas[i] = gate_vma; 1030 i++; 1031 start += PAGE_SIZE; 1032 len--; 1033 continue; 1034 } 1035 1036 if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP)) 1037 || !(vm_flags & vma->vm_flags)) 1038 return i ? : -EFAULT; 1039 1040 if (is_vm_hugetlb_page(vma)) { 1041 i = follow_hugetlb_page(mm, vma, pages, vmas, 1042 &start, &len, i); 1043 continue; 1044 } 1045 1046 foll_flags = FOLL_TOUCH; 1047 if (pages) 1048 foll_flags |= FOLL_GET; 1049 if (!write && !(vma->vm_flags & VM_LOCKED) && 1050 (!vma->vm_ops || (!vma->vm_ops->nopage && 1051 !vma->vm_ops->fault))) 1052 foll_flags |= FOLL_ANON; 1053 1054 do { 1055 struct page *page; 1056 1057 /* 1058 * If tsk is ooming, cut off its access to large memory 1059 * allocations. It has a pending SIGKILL, but it can't 1060 * be processed until returning to user space. 1061 */ 1062 if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE))) 1063 return -ENOMEM; 1064 1065 if (write) 1066 foll_flags |= FOLL_WRITE; 1067 1068 cond_resched(); 1069 while (!(page = follow_page(vma, start, foll_flags))) { 1070 int ret; 1071 ret = __handle_mm_fault(mm, vma, start, 1072 foll_flags & FOLL_WRITE); 1073 /* 1074 * The VM_FAULT_WRITE bit tells us that do_wp_page has 1075 * broken COW when necessary, even if maybe_mkwrite 1076 * decided not to set pte_write. We can thus safely do 1077 * subsequent page lookups as if they were reads. 1078 */ 1079 if (ret & VM_FAULT_WRITE) 1080 foll_flags &= ~FOLL_WRITE; 1081 1082 switch (ret & ~VM_FAULT_WRITE) { 1083 case VM_FAULT_MINOR: 1084 tsk->min_flt++; 1085 break; 1086 case VM_FAULT_MAJOR: 1087 tsk->maj_flt++; 1088 break; 1089 case VM_FAULT_SIGBUS: 1090 return i ? i : -EFAULT; 1091 case VM_FAULT_OOM: 1092 return i ? i : -ENOMEM; 1093 default: 1094 BUG(); 1095 } 1096 cond_resched(); 1097 } 1098 if (pages) { 1099 pages[i] = page; 1100 1101 flush_anon_page(vma, page, start); 1102 flush_dcache_page(page); 1103 } 1104 if (vmas) 1105 vmas[i] = vma; 1106 i++; 1107 start += PAGE_SIZE; 1108 len--; 1109 } while (len && start < vma->vm_end); 1110 } while (len); 1111 return i; 1112} 1113EXPORT_SYMBOL(get_user_pages); 1114 1115static int zeromap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1116 unsigned long addr, unsigned long end, pgprot_t prot) 1117{ 1118 pte_t *pte; 1119 spinlock_t *ptl; 1120 int err = 0; 1121 1122 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1123 if (!pte) 1124 return -EAGAIN; 1125 arch_enter_lazy_mmu_mode(); 1126 do { 1127 struct page *page = ZERO_PAGE(addr); 1128 pte_t zero_pte = pte_wrprotect(mk_pte(page, prot)); 1129 1130 if (unlikely(!pte_none(*pte))) { 1131 err = -EEXIST; 1132 pte++; 1133 break; 1134 } 1135 page_cache_get(page); 1136 page_add_file_rmap(page); 1137 inc_mm_counter(mm, file_rss); 1138 set_pte_at(mm, addr, pte, zero_pte); 1139 } while (pte++, addr += PAGE_SIZE, addr != end); 1140 arch_leave_lazy_mmu_mode(); 1141 pte_unmap_unlock(pte - 1, ptl); 1142 return err; 1143} 1144 1145static inline int zeromap_pmd_range(struct mm_struct *mm, pud_t *pud, 1146 unsigned long addr, unsigned long end, pgprot_t prot) 1147{ 1148 pmd_t *pmd; 1149 unsigned long next; 1150 int err; 1151 1152 pmd = pmd_alloc(mm, pud, addr); 1153 if (!pmd) 1154 return -EAGAIN; 1155 do { 1156 next = pmd_addr_end(addr, end); 1157 err = zeromap_pte_range(mm, pmd, addr, next, prot); 1158 if (err) 1159 break; 1160 } while (pmd++, addr = next, addr != end); 1161 return err; 1162} 1163 1164static inline int zeromap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1165 unsigned long addr, unsigned long end, pgprot_t prot) 1166{ 1167 pud_t *pud; 1168 unsigned long next; 1169 int err; 1170 1171 pud = pud_alloc(mm, pgd, addr); 1172 if (!pud) 1173 return -EAGAIN; 1174 do { 1175 next = pud_addr_end(addr, end); 1176 err = zeromap_pmd_range(mm, pud, addr, next, prot); 1177 if (err) 1178 break; 1179 } while (pud++, addr = next, addr != end); 1180 return err; 1181} 1182 1183int zeromap_page_range(struct vm_area_struct *vma, 1184 unsigned long addr, unsigned long size, pgprot_t prot) 1185{ 1186 pgd_t *pgd; 1187 unsigned long next; 1188 unsigned long end = addr + size; 1189 struct mm_struct *mm = vma->vm_mm; 1190 int err; 1191 1192 BUG_ON(addr >= end); 1193 pgd = pgd_offset(mm, addr); 1194 flush_cache_range(vma, addr, end); 1195 do { 1196 next = pgd_addr_end(addr, end); 1197 err = zeromap_pud_range(mm, pgd, addr, next, prot); 1198 if (err) 1199 break; 1200 } while (pgd++, addr = next, addr != end); 1201 return err; 1202} 1203 1204pte_t * fastcall get_locked_pte(struct mm_struct *mm, unsigned long addr, spinlock_t **ptl) 1205{ 1206 pgd_t * pgd = pgd_offset(mm, addr); 1207 pud_t * pud = pud_alloc(mm, pgd, addr); 1208 if (pud) { 1209 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1210 if (pmd) 1211 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1212 } 1213 return NULL; 1214} 1215 1216/* 1217 * This is the old fallback for page remapping. 1218 * 1219 * For historical reasons, it only allows reserved pages. Only 1220 * old drivers should use this, and they needed to mark their 1221 * pages reserved for the old functions anyway. 1222 */ 1223static int insert_page(struct mm_struct *mm, unsigned long addr, struct page *page, pgprot_t prot) 1224{ 1225 int retval; 1226 pte_t *pte; 1227 spinlock_t *ptl; 1228 1229 retval = -EINVAL; 1230 if (PageAnon(page)) 1231 goto out; 1232 retval = -ENOMEM; 1233 flush_dcache_page(page); 1234 pte = get_locked_pte(mm, addr, &ptl); 1235 if (!pte) 1236 goto out; 1237 retval = -EBUSY; 1238 if (!pte_none(*pte)) 1239 goto out_unlock; 1240 1241 /* Ok, finally just insert the thing.. */ 1242 get_page(page); 1243 inc_mm_counter(mm, file_rss); 1244 page_add_file_rmap(page); 1245 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1246 1247 retval = 0; 1248out_unlock: 1249 pte_unmap_unlock(pte, ptl); 1250out: 1251 return retval; 1252} 1253 1254/** 1255 * vm_insert_page - insert single page into user vma 1256 * @vma: user vma to map to 1257 * @addr: target user address of this page 1258 * @page: source kernel page 1259 * 1260 * This allows drivers to insert individual pages they've allocated 1261 * into a user vma. 1262 * 1263 * The page has to be a nice clean _individual_ kernel allocation. 1264 * If you allocate a compound page, you need to have marked it as 1265 * such (__GFP_COMP), or manually just split the page up yourself 1266 * (see split_page()). 1267 * 1268 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1269 * took an arbitrary page protection parameter. This doesn't allow 1270 * that. Your vma protection will have to be set up correctly, which 1271 * means that if you want a shared writable mapping, you'd better 1272 * ask for a shared writable mapping! 1273 * 1274 * The page does not need to be reserved. 1275 */ 1276int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page *page) 1277{ 1278 if (addr < vma->vm_start || addr >= vma->vm_end) 1279 return -EFAULT; 1280 if (!page_count(page)) 1281 return -EINVAL; 1282 vma->vm_flags |= VM_INSERTPAGE; 1283 return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot); 1284} 1285EXPORT_SYMBOL(vm_insert_page); 1286 1287/** 1288 * vm_insert_pfn - insert single pfn into user vma 1289 * @vma: user vma to map to 1290 * @addr: target user address of this page 1291 * @pfn: source kernel pfn 1292 * 1293 * Similar to vm_inert_page, this allows drivers to insert individual pages 1294 * they've allocated into a user vma. Same comments apply. 1295 * 1296 * This function should only be called from a vm_ops->fault handler, and 1297 * in that case the handler should return NULL. 1298 */ 1299int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1300 unsigned long pfn) 1301{ 1302 struct mm_struct *mm = vma->vm_mm; 1303 int retval; 1304 pte_t *pte, entry; 1305 spinlock_t *ptl; 1306 1307 BUG_ON(!(vma->vm_flags & VM_PFNMAP)); 1308 BUG_ON(is_cow_mapping(vma->vm_flags)); 1309 1310 retval = -ENOMEM; 1311 pte = get_locked_pte(mm, addr, &ptl); 1312 if (!pte) 1313 goto out; 1314 retval = -EBUSY; 1315 if (!pte_none(*pte)) 1316 goto out_unlock; 1317 1318 /* Ok, finally just insert the thing.. */ 1319 entry = pfn_pte(pfn, vma->vm_page_prot); 1320 set_pte_at(mm, addr, pte, entry); 1321 update_mmu_cache(vma, addr, entry); 1322 1323 retval = 0; 1324out_unlock: 1325 pte_unmap_unlock(pte, ptl); 1326 1327out: 1328 return retval; 1329} 1330EXPORT_SYMBOL(vm_insert_pfn); 1331 1332/* 1333 * maps a range of physical memory into the requested pages. the old 1334 * mappings are removed. any references to nonexistent pages results 1335 * in null mappings (currently treated as "copy-on-access") 1336 */ 1337static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1338 unsigned long addr, unsigned long end, 1339 unsigned long pfn, pgprot_t prot) 1340{ 1341 pte_t *pte; 1342 spinlock_t *ptl; 1343 1344 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1345 if (!pte) 1346 return -ENOMEM; 1347 arch_enter_lazy_mmu_mode(); 1348 do { 1349 BUG_ON(!pte_none(*pte)); 1350 set_pte_at(mm, addr, pte, pfn_pte(pfn, prot)); 1351 pfn++; 1352 } while (pte++, addr += PAGE_SIZE, addr != end); 1353 arch_leave_lazy_mmu_mode(); 1354 pte_unmap_unlock(pte - 1, ptl); 1355 return 0; 1356} 1357 1358static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1359 unsigned long addr, unsigned long end, 1360 unsigned long pfn, pgprot_t prot) 1361{ 1362 pmd_t *pmd; 1363 unsigned long next; 1364 1365 pfn -= addr >> PAGE_SHIFT; 1366 pmd = pmd_alloc(mm, pud, addr); 1367 if (!pmd) 1368 return -ENOMEM; 1369 do { 1370 next = pmd_addr_end(addr, end); 1371 if (remap_pte_range(mm, pmd, addr, next, 1372 pfn + (addr >> PAGE_SHIFT), prot)) 1373 return -ENOMEM; 1374 } while (pmd++, addr = next, addr != end); 1375 return 0; 1376} 1377 1378static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1379 unsigned long addr, unsigned long end, 1380 unsigned long pfn, pgprot_t prot) 1381{ 1382 pud_t *pud; 1383 unsigned long next; 1384 1385 pfn -= addr >> PAGE_SHIFT; 1386 pud = pud_alloc(mm, pgd, addr); 1387 if (!pud) 1388 return -ENOMEM; 1389 do { 1390 next = pud_addr_end(addr, end); 1391 if (remap_pmd_range(mm, pud, addr, next, 1392 pfn + (addr >> PAGE_SHIFT), prot)) 1393 return -ENOMEM; 1394 } while (pud++, addr = next, addr != end); 1395 return 0; 1396} 1397 1398/** 1399 * remap_pfn_range - remap kernel memory to userspace 1400 * @vma: user vma to map to 1401 * @addr: target user address to start at 1402 * @pfn: physical address of kernel memory 1403 * @size: size of map area 1404 * @prot: page protection flags for this mapping 1405 * 1406 * Note: this is only safe if the mm semaphore is held when called. 1407 */ 1408int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1409 unsigned long pfn, unsigned long size, pgprot_t prot) 1410{ 1411 pgd_t *pgd; 1412 unsigned long next; 1413 unsigned long end = addr + PAGE_ALIGN(size); 1414 struct mm_struct *mm = vma->vm_mm; 1415 int err; 1416 1417 /* 1418 * Physically remapped pages are special. Tell the 1419 * rest of the world about it: 1420 * VM_IO tells people not to look at these pages 1421 * (accesses can have side effects). 1422 * VM_RESERVED is specified all over the place, because 1423 * in 2.4 it kept swapout's vma scan off this vma; but 1424 * in 2.6 the LRU scan won't even find its pages, so this 1425 * flag means no more than count its pages in reserved_vm, 1426 * and omit it from core dump, even when VM_IO turned off. 1427 * VM_PFNMAP tells the core MM that the base pages are just 1428 * raw PFN mappings, and do not have a "struct page" associated 1429 * with them. 1430 * 1431 * There's a horrible special case to handle copy-on-write 1432 * behaviour that some programs depend on. We mark the "original" 1433 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1434 */ 1435 if (is_cow_mapping(vma->vm_flags)) { 1436 if (addr != vma->vm_start || end != vma->vm_end) 1437 return -EINVAL; 1438 vma->vm_pgoff = pfn; 1439 } 1440 1441 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 1442 1443 BUG_ON(addr >= end); 1444 pfn -= addr >> PAGE_SHIFT; 1445 pgd = pgd_offset(mm, addr); 1446 flush_cache_range(vma, addr, end); 1447 do { 1448 next = pgd_addr_end(addr, end); 1449 err = remap_pud_range(mm, pgd, addr, next, 1450 pfn + (addr >> PAGE_SHIFT), prot); 1451 if (err) 1452 break; 1453 } while (pgd++, addr = next, addr != end); 1454 return err; 1455} 1456EXPORT_SYMBOL(remap_pfn_range); 1457 1458static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 1459 unsigned long addr, unsigned long end, 1460 pte_fn_t fn, void *data) 1461{ 1462 pte_t *pte; 1463 int err; 1464 struct page *pmd_page; 1465 spinlock_t *uninitialized_var(ptl); 1466 1467 pte = (mm == &init_mm) ? 1468 pte_alloc_kernel(pmd, addr) : 1469 pte_alloc_map_lock(mm, pmd, addr, &ptl); 1470 if (!pte) 1471 return -ENOMEM; 1472 1473 BUG_ON(pmd_huge(*pmd)); 1474 1475 pmd_page = pmd_page(*pmd); 1476 1477 do { 1478 err = fn(pte, pmd_page, addr, data); 1479 if (err) 1480 break; 1481 } while (pte++, addr += PAGE_SIZE, addr != end); 1482 1483 if (mm != &init_mm) 1484 pte_unmap_unlock(pte-1, ptl); 1485 return err; 1486} 1487 1488static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 1489 unsigned long addr, unsigned long end, 1490 pte_fn_t fn, void *data) 1491{ 1492 pmd_t *pmd; 1493 unsigned long next; 1494 int err; 1495 1496 pmd = pmd_alloc(mm, pud, addr); 1497 if (!pmd) 1498 return -ENOMEM; 1499 do { 1500 next = pmd_addr_end(addr, end); 1501 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 1502 if (err) 1503 break; 1504 } while (pmd++, addr = next, addr != end); 1505 return err; 1506} 1507 1508static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 1509 unsigned long addr, unsigned long end, 1510 pte_fn_t fn, void *data) 1511{ 1512 pud_t *pud; 1513 unsigned long next; 1514 int err; 1515 1516 pud = pud_alloc(mm, pgd, addr); 1517 if (!pud) 1518 return -ENOMEM; 1519 do { 1520 next = pud_addr_end(addr, end); 1521 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 1522 if (err) 1523 break; 1524 } while (pud++, addr = next, addr != end); 1525 return err; 1526} 1527 1528/* 1529 * Scan a region of virtual memory, filling in page tables as necessary 1530 * and calling a provided function on each leaf page table. 1531 */ 1532int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 1533 unsigned long size, pte_fn_t fn, void *data) 1534{ 1535 pgd_t *pgd; 1536 unsigned long next; 1537 unsigned long end = addr + size; 1538 int err; 1539 1540 BUG_ON(addr >= end); 1541 pgd = pgd_offset(mm, addr); 1542 do { 1543 next = pgd_addr_end(addr, end); 1544 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 1545 if (err) 1546 break; 1547 } while (pgd++, addr = next, addr != end); 1548 return err; 1549} 1550EXPORT_SYMBOL_GPL(apply_to_page_range); 1551 1552/* 1553 * handle_pte_fault chooses page fault handler according to an entry 1554 * which was read non-atomically. Before making any commitment, on 1555 * those architectures or configurations (e.g. i386 with PAE) which 1556 * might give a mix of unmatched parts, do_swap_page and do_file_page 1557 * must check under lock before unmapping the pte and proceeding 1558 * (but do_wp_page is only called after already making such a check; 1559 * and do_anonymous_page and do_no_page can safely check later on). 1560 */ 1561static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1562 pte_t *page_table, pte_t orig_pte) 1563{ 1564 int same = 1; 1565#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1566 if (sizeof(pte_t) > sizeof(unsigned long)) { 1567 spinlock_t *ptl = pte_lockptr(mm, pmd); 1568 spin_lock(ptl); 1569 same = pte_same(*page_table, orig_pte); 1570 spin_unlock(ptl); 1571 } 1572#endif 1573 pte_unmap(page_table); 1574 return same; 1575} 1576 1577/* 1578 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1579 * servicing faults for write access. In the normal case, do always want 1580 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1581 * that do not have writing enabled, when used by access_process_vm. 1582 */ 1583static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1584{ 1585 if (likely(vma->vm_flags & VM_WRITE)) 1586 pte = pte_mkwrite(pte); 1587 return pte; 1588} 1589 1590static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1591{ 1592 /* 1593 * If the source page was a PFN mapping, we don't have 1594 * a "struct page" for it. We do a best-effort copy by 1595 * just copying from the original user address. If that 1596 * fails, we just zero-fill it. Live with it. 1597 */ 1598 if (unlikely(!src)) { 1599 void *kaddr = kmap_atomic(dst, KM_USER0); 1600 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1601 1602 /* 1603 * This really shouldn't fail, because the page is there 1604 * in the page tables. But it might just be unreadable, 1605 * in which case we just give up and fill the result with 1606 * zeroes. 1607 */ 1608 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1609 memset(kaddr, 0, PAGE_SIZE); 1610 kunmap_atomic(kaddr, KM_USER0); 1611 flush_dcache_page(dst); 1612 return; 1613 1614 } 1615 copy_user_highpage(dst, src, va, vma); 1616} 1617 1618/* 1619 * This routine handles present pages, when users try to write 1620 * to a shared page. It is done by copying the page to a new address 1621 * and decrementing the shared-page counter for the old page. 1622 * 1623 * Note that this routine assumes that the protection checks have been 1624 * done by the caller (the low-level page fault routine in most cases). 1625 * Thus we can safely just mark it writable once we've done any necessary 1626 * COW. 1627 * 1628 * We also mark the page dirty at this point even though the page will 1629 * change only once the write actually happens. This avoids a few races, 1630 * and potentially makes it more efficient. 1631 * 1632 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1633 * but allow concurrent faults), with pte both mapped and locked. 1634 * We return with mmap_sem still held, but pte unmapped and unlocked. 1635 */ 1636static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1637 unsigned long address, pte_t *page_table, pmd_t *pmd, 1638 spinlock_t *ptl, pte_t orig_pte) 1639{ 1640 struct page *old_page, *new_page; 1641 pte_t entry; 1642 int reuse = 0, ret = VM_FAULT_MINOR; 1643 struct page *dirty_page = NULL; 1644 1645 old_page = vm_normal_page(vma, address, orig_pte); 1646 if (!old_page) 1647 goto gotten; 1648 1649 /* 1650 * Take out anonymous pages first, anonymous shared vmas are 1651 * not dirty accountable. 1652 */ 1653 if (PageAnon(old_page)) { 1654 if (!TestSetPageLocked(old_page)) { 1655 reuse = can_share_swap_page(old_page); 1656 unlock_page(old_page); 1657 } 1658 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 1659 (VM_WRITE|VM_SHARED))) { 1660 /* 1661 * Only catch write-faults on shared writable pages, 1662 * read-only shared pages can get COWed by 1663 * get_user_pages(.write=1, .force=1). 1664 */ 1665 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 1666 /* 1667 * Notify the address space that the page is about to 1668 * become writable so that it can prohibit this or wait 1669 * for the page to get into an appropriate state. 1670 * 1671 * We do this without the lock held, so that it can 1672 * sleep if it needs to. 1673 */ 1674 page_cache_get(old_page); 1675 pte_unmap_unlock(page_table, ptl); 1676 1677 if (vma->vm_ops->page_mkwrite(vma, old_page) < 0) 1678 goto unwritable_page; 1679 1680 /* 1681 * Since we dropped the lock we need to revalidate 1682 * the PTE as someone else may have changed it. If 1683 * they did, we just return, as we can count on the 1684 * MMU to tell us if they didn't also make it writable. 1685 */ 1686 page_table = pte_offset_map_lock(mm, pmd, address, 1687 &ptl); 1688 page_cache_release(old_page); 1689 if (!pte_same(*page_table, orig_pte)) 1690 goto unlock; 1691 } 1692 dirty_page = old_page; 1693 get_page(dirty_page); 1694 reuse = 1; 1695 } 1696 1697 if (reuse) { 1698 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1699 entry = pte_mkyoung(orig_pte); 1700 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1701 if (ptep_set_access_flags(vma, address, page_table, entry,1)) { 1702 update_mmu_cache(vma, address, entry); 1703 lazy_mmu_prot_update(entry); 1704 } 1705 ret |= VM_FAULT_WRITE; 1706 goto unlock; 1707 } 1708 1709 /* 1710 * Ok, we need to copy. Oh, well.. 1711 */ 1712 page_cache_get(old_page); 1713gotten: 1714 pte_unmap_unlock(page_table, ptl); 1715 1716 if (unlikely(anon_vma_prepare(vma))) 1717 goto oom; 1718 if (old_page == ZERO_PAGE(address)) { 1719 new_page = alloc_zeroed_user_highpage_movable(vma, address); 1720 if (!new_page) 1721 goto oom; 1722 } else { 1723 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 1724 if (!new_page) 1725 goto oom; 1726 cow_user_page(new_page, old_page, address, vma); 1727 } 1728 1729 /* 1730 * Re-check the pte - we dropped the lock 1731 */ 1732 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 1733 if (likely(pte_same(*page_table, orig_pte))) { 1734 if (old_page) { 1735 page_remove_rmap(old_page, vma); 1736 if (!PageAnon(old_page)) { 1737 dec_mm_counter(mm, file_rss); 1738 inc_mm_counter(mm, anon_rss); 1739 } 1740 } else 1741 inc_mm_counter(mm, anon_rss); 1742 flush_cache_page(vma, address, pte_pfn(orig_pte)); 1743 entry = mk_pte(new_page, vma->vm_page_prot); 1744 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 1745 lazy_mmu_prot_update(entry); 1746 /* 1747 * Clear the pte entry and flush it first, before updating the 1748 * pte with the new entry. This will avoid a race condition 1749 * seen in the presence of one thread doing SMC and another 1750 * thread doing COW. 1751 */ 1752 ptep_clear_flush(vma, address, page_table); 1753 set_pte_at(mm, address, page_table, entry); 1754 update_mmu_cache(vma, address, entry); 1755 lru_cache_add_active(new_page); 1756 page_add_new_anon_rmap(new_page, vma, address); 1757 1758 /* Free the old page.. */ 1759 new_page = old_page; 1760 ret |= VM_FAULT_WRITE; 1761 } 1762 if (new_page) 1763 page_cache_release(new_page); 1764 if (old_page) 1765 page_cache_release(old_page); 1766unlock: 1767 pte_unmap_unlock(page_table, ptl); 1768 if (dirty_page) { 1769 set_page_dirty_balance(dirty_page); 1770 put_page(dirty_page); 1771 } 1772 return ret; 1773oom: 1774 if (old_page) 1775 page_cache_release(old_page); 1776 return VM_FAULT_OOM; 1777 1778unwritable_page: 1779 page_cache_release(old_page); 1780 return VM_FAULT_SIGBUS; 1781} 1782 1783/* 1784 * Helper functions for unmap_mapping_range(). 1785 * 1786 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 1787 * 1788 * We have to restart searching the prio_tree whenever we drop the lock, 1789 * since the iterator is only valid while the lock is held, and anyway 1790 * a later vma might be split and reinserted earlier while lock dropped. 1791 * 1792 * The list of nonlinear vmas could be handled more efficiently, using 1793 * a placeholder, but handle it in the same way until a need is shown. 1794 * It is important to search the prio_tree before nonlinear list: a vma 1795 * may become nonlinear and be shifted from prio_tree to nonlinear list 1796 * while the lock is dropped; but never shifted from list to prio_tree. 1797 * 1798 * In order to make forward progress despite restarting the search, 1799 * vm_truncate_count is used to mark a vma as now dealt with, so we can 1800 * quickly skip it next time around. Since the prio_tree search only 1801 * shows us those vmas affected by unmapping the range in question, we 1802 * can't efficiently keep all vmas in step with mapping->truncate_count: 1803 * so instead reset them all whenever it wraps back to 0 (then go to 1). 1804 * mapping->truncate_count and vma->vm_truncate_count are protected by 1805 * i_mmap_lock. 1806 * 1807 * In order to make forward progress despite repeatedly restarting some 1808 * large vma, note the restart_addr from unmap_vmas when it breaks out: 1809 * and restart from that address when we reach that vma again. It might 1810 * have been split or merged, shrunk or extended, but never shifted: so 1811 * restart_addr remains valid so long as it remains in the vma's range. 1812 * unmap_mapping_range forces truncate_count to leap over page-aligned 1813 * values so we can save vma's restart_addr in its truncate_count field. 1814 */ 1815#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 1816 1817static void reset_vma_truncate_counts(struct address_space *mapping) 1818{ 1819 struct vm_area_struct *vma; 1820 struct prio_tree_iter iter; 1821 1822 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 1823 vma->vm_truncate_count = 0; 1824 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 1825 vma->vm_truncate_count = 0; 1826} 1827 1828static int unmap_mapping_range_vma(struct vm_area_struct *vma, 1829 unsigned long start_addr, unsigned long end_addr, 1830 struct zap_details *details) 1831{ 1832 unsigned long restart_addr; 1833 int need_break; 1834 1835 /* 1836 * files that support invalidating or truncating portions of the 1837 * file from under mmaped areas must set the VM_CAN_INVALIDATE flag, and 1838 * have their .nopage function return the page locked. 1839 */ 1840 BUG_ON(!(vma->vm_flags & VM_CAN_INVALIDATE)); 1841 1842again: 1843 restart_addr = vma->vm_truncate_count; 1844 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 1845 start_addr = restart_addr; 1846 if (start_addr >= end_addr) { 1847 /* Top of vma has been split off since last time */ 1848 vma->vm_truncate_count = details->truncate_count; 1849 return 0; 1850 } 1851 } 1852 1853 restart_addr = zap_page_range(vma, start_addr, 1854 end_addr - start_addr, details); 1855 need_break = need_resched() || 1856 need_lockbreak(details->i_mmap_lock); 1857 1858 if (restart_addr >= end_addr) { 1859 /* We have now completed this vma: mark it so */ 1860 vma->vm_truncate_count = details->truncate_count; 1861 if (!need_break) 1862 return 0; 1863 } else { 1864 /* Note restart_addr in vma's truncate_count field */ 1865 vma->vm_truncate_count = restart_addr; 1866 if (!need_break) 1867 goto again; 1868 } 1869 1870 spin_unlock(details->i_mmap_lock); 1871 cond_resched(); 1872 spin_lock(details->i_mmap_lock); 1873 return -EINTR; 1874} 1875 1876static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 1877 struct zap_details *details) 1878{ 1879 struct vm_area_struct *vma; 1880 struct prio_tree_iter iter; 1881 pgoff_t vba, vea, zba, zea; 1882 1883restart: 1884 vma_prio_tree_foreach(vma, &iter, root, 1885 details->first_index, details->last_index) { 1886 /* Skip quickly over those we have already dealt with */ 1887 if (vma->vm_truncate_count == details->truncate_count) 1888 continue; 1889 1890 vba = vma->vm_pgoff; 1891 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 1892 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 1893 zba = details->first_index; 1894 if (zba < vba) 1895 zba = vba; 1896 zea = details->last_index; 1897 if (zea > vea) 1898 zea = vea; 1899 1900 if (unmap_mapping_range_vma(vma, 1901 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 1902 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 1903 details) < 0) 1904 goto restart; 1905 } 1906} 1907 1908static inline void unmap_mapping_range_list(struct list_head *head, 1909 struct zap_details *details) 1910{ 1911 struct vm_area_struct *vma; 1912 1913 /* 1914 * In nonlinear VMAs there is no correspondence between virtual address 1915 * offset and file offset. So we must perform an exhaustive search 1916 * across *all* the pages in each nonlinear VMA, not just the pages 1917 * whose virtual address lies outside the file truncation point. 1918 */ 1919restart: 1920 list_for_each_entry(vma, head, shared.vm_set.list) { 1921 /* Skip quickly over those we have already dealt with */ 1922 if (vma->vm_truncate_count == details->truncate_count) 1923 continue; 1924 details->nonlinear_vma = vma; 1925 if (unmap_mapping_range_vma(vma, vma->vm_start, 1926 vma->vm_end, details) < 0) 1927 goto restart; 1928 } 1929} 1930 1931/** 1932 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 1933 * @mapping: the address space containing mmaps to be unmapped. 1934 * @holebegin: byte in first page to unmap, relative to the start of 1935 * the underlying file. This will be rounded down to a PAGE_SIZE 1936 * boundary. Note that this is different from vmtruncate(), which 1937 * must keep the partial page. In contrast, we must get rid of 1938 * partial pages. 1939 * @holelen: size of prospective hole in bytes. This will be rounded 1940 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 1941 * end of the file. 1942 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 1943 * but 0 when invalidating pagecache, don't throw away private data. 1944 */ 1945void unmap_mapping_range(struct address_space *mapping, 1946 loff_t const holebegin, loff_t const holelen, int even_cows) 1947{ 1948 struct zap_details details; 1949 pgoff_t hba = holebegin >> PAGE_SHIFT; 1950 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1951 1952 /* Check for overflow. */ 1953 if (sizeof(holelen) > sizeof(hlen)) { 1954 long long holeend = 1955 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1956 if (holeend & ~(long long)ULONG_MAX) 1957 hlen = ULONG_MAX - hba + 1; 1958 } 1959 1960 details.check_mapping = even_cows? NULL: mapping; 1961 details.nonlinear_vma = NULL; 1962 details.first_index = hba; 1963 details.last_index = hba + hlen - 1; 1964 if (details.last_index < details.first_index) 1965 details.last_index = ULONG_MAX; 1966 details.i_mmap_lock = &mapping->i_mmap_lock; 1967 1968 spin_lock(&mapping->i_mmap_lock); 1969 1970 /* Protect against endless unmapping loops */ 1971 mapping->truncate_count++; 1972 if (unlikely(is_restart_addr(mapping->truncate_count))) { 1973 if (mapping->truncate_count == 0) 1974 reset_vma_truncate_counts(mapping); 1975 mapping->truncate_count++; 1976 } 1977 details.truncate_count = mapping->truncate_count; 1978 1979 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 1980 unmap_mapping_range_tree(&mapping->i_mmap, &details); 1981 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 1982 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 1983 spin_unlock(&mapping->i_mmap_lock); 1984} 1985EXPORT_SYMBOL(unmap_mapping_range); 1986 1987/** 1988 * vmtruncate - unmap mappings "freed" by truncate() syscall 1989 * @inode: inode of the file used 1990 * @offset: file offset to start truncating 1991 * 1992 * NOTE! We have to be ready to update the memory sharing 1993 * between the file and the memory map for a potential last 1994 * incomplete page. Ugly, but necessary. 1995 */ 1996int vmtruncate(struct inode * inode, loff_t offset) 1997{ 1998 struct address_space *mapping = inode->i_mapping; 1999 unsigned long limit; 2000 2001 if (inode->i_size < offset) 2002 goto do_expand; 2003 /* 2004 * truncation of in-use swapfiles is disallowed - it would cause 2005 * subsequent swapout to scribble on the now-freed blocks. 2006 */ 2007 if (IS_SWAPFILE(inode)) 2008 goto out_busy; 2009 i_size_write(inode, offset); 2010 2011 /* 2012 * unmap_mapping_range is called twice, first simply for efficiency 2013 * so that truncate_inode_pages does fewer single-page unmaps. However 2014 * after this first call, and before truncate_inode_pages finishes, 2015 * it is possible for private pages to be COWed, which remain after 2016 * truncate_inode_pages finishes, hence the second unmap_mapping_range 2017 * call must be made for correctness. 2018 */ 2019 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 2020 truncate_inode_pages(mapping, offset); 2021 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 2022 goto out_truncate; 2023 2024do_expand: 2025 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 2026 if (limit != RLIM_INFINITY && offset > limit) 2027 goto out_sig; 2028 if (offset > inode->i_sb->s_maxbytes) 2029 goto out_big; 2030 i_size_write(inode, offset); 2031 2032out_truncate: 2033 if (inode->i_op && inode->i_op->truncate) 2034 inode->i_op->truncate(inode); 2035 return 0; 2036out_sig: 2037 send_sig(SIGXFSZ, current, 0); 2038out_big: 2039 return -EFBIG; 2040out_busy: 2041 return -ETXTBSY; 2042} 2043EXPORT_SYMBOL(vmtruncate); 2044 2045int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 2046{ 2047 struct address_space *mapping = inode->i_mapping; 2048 2049 /* 2050 * If the underlying filesystem is not going to provide 2051 * a way to truncate a range of blocks (punch a hole) - 2052 * we should return failure right now. 2053 */ 2054 if (!inode->i_op || !inode->i_op->truncate_range) 2055 return -ENOSYS; 2056 2057 mutex_lock(&inode->i_mutex); 2058 down_write(&inode->i_alloc_sem); 2059 unmap_mapping_range(mapping, offset, (end - offset), 1); 2060 truncate_inode_pages_range(mapping, offset, end); 2061 unmap_mapping_range(mapping, offset, (end - offset), 1); 2062 inode->i_op->truncate_range(inode, offset, end); 2063 up_write(&inode->i_alloc_sem); 2064 mutex_unlock(&inode->i_mutex); 2065 2066 return 0; 2067} 2068 2069/** 2070 * swapin_readahead - swap in pages in hope we need them soon 2071 * @entry: swap entry of this memory 2072 * @addr: address to start 2073 * @vma: user vma this addresses belong to 2074 * 2075 * Primitive swap readahead code. We simply read an aligned block of 2076 * (1 << page_cluster) entries in the swap area. This method is chosen 2077 * because it doesn't cost us any seek time. We also make sure to queue 2078 * the 'original' request together with the readahead ones... 2079 * 2080 * This has been extended to use the NUMA policies from the mm triggering 2081 * the readahead. 2082 * 2083 * Caller must hold down_read on the vma->vm_mm if vma is not NULL. 2084 */ 2085void swapin_readahead(swp_entry_t entry, unsigned long addr,struct vm_area_struct *vma) 2086{ 2087#ifdef CONFIG_NUMA 2088 struct vm_area_struct *next_vma = vma ? vma->vm_next : NULL; 2089#endif 2090 int i, num; 2091 struct page *new_page; 2092 unsigned long offset; 2093 2094 /* 2095 * Get the number of handles we should do readahead io to. 2096 */ 2097 num = valid_swaphandles(entry, &offset); 2098 for (i = 0; i < num; offset++, i++) { 2099 /* Ok, do the async read-ahead now */ 2100 new_page = read_swap_cache_async(swp_entry(swp_type(entry), 2101 offset), vma, addr); 2102 if (!new_page) 2103 break; 2104 page_cache_release(new_page); 2105#ifdef CONFIG_NUMA 2106 /* 2107 * Find the next applicable VMA for the NUMA policy. 2108 */ 2109 addr += PAGE_SIZE; 2110 if (addr == 0) 2111 vma = NULL; 2112 if (vma) { 2113 if (addr >= vma->vm_end) { 2114 vma = next_vma; 2115 next_vma = vma ? vma->vm_next : NULL; 2116 } 2117 if (vma && addr < vma->vm_start) 2118 vma = NULL; 2119 } else { 2120 if (next_vma && addr >= next_vma->vm_start) { 2121 vma = next_vma; 2122 next_vma = vma->vm_next; 2123 } 2124 } 2125#endif 2126 } 2127 lru_add_drain(); /* Push any new pages onto the LRU now */ 2128} 2129 2130/* 2131 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2132 * but allow concurrent faults), and pte mapped but not yet locked. 2133 * We return with mmap_sem still held, but pte unmapped and unlocked. 2134 */ 2135static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2136 unsigned long address, pte_t *page_table, pmd_t *pmd, 2137 int write_access, pte_t orig_pte) 2138{ 2139 spinlock_t *ptl; 2140 struct page *page; 2141 swp_entry_t entry; 2142 pte_t pte; 2143 int ret = VM_FAULT_MINOR; 2144 2145 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2146 goto out; 2147 2148 entry = pte_to_swp_entry(orig_pte); 2149 if (is_migration_entry(entry)) { 2150 migration_entry_wait(mm, pmd, address); 2151 goto out; 2152 } 2153 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2154 page = lookup_swap_cache(entry); 2155 if (!page) { 2156 grab_swap_token(); /* Contend for token _before_ read-in */ 2157 swapin_readahead(entry, address, vma); 2158 page = read_swap_cache_async(entry, vma, address); 2159 if (!page) { 2160 /* 2161 * Back out if somebody else faulted in this pte 2162 * while we released the pte lock. 2163 */ 2164 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2165 if (likely(pte_same(*page_table, orig_pte))) 2166 ret = VM_FAULT_OOM; 2167 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2168 goto unlock; 2169 } 2170 2171 /* Had to read the page from swap area: Major fault */ 2172 ret = VM_FAULT_MAJOR; 2173 count_vm_event(PGMAJFAULT); 2174 } 2175 2176 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2177 mark_page_accessed(page); 2178 lock_page(page); 2179 2180 /* 2181 * Back out if somebody else already faulted in this pte. 2182 */ 2183 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2184 if (unlikely(!pte_same(*page_table, orig_pte))) 2185 goto out_nomap; 2186 2187 if (unlikely(!PageUptodate(page))) { 2188 ret = VM_FAULT_SIGBUS; 2189 goto out_nomap; 2190 } 2191 2192 /* The page isn't present yet, go ahead with the fault. */ 2193 2194 inc_mm_counter(mm, anon_rss); 2195 pte = mk_pte(page, vma->vm_page_prot); 2196 if (write_access && can_share_swap_page(page)) { 2197 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2198 write_access = 0; 2199 } 2200 2201 flush_icache_page(vma, page); 2202 set_pte_at(mm, address, page_table, pte); 2203 page_add_anon_rmap(page, vma, address); 2204 2205 swap_free(entry); 2206 if (vm_swap_full()) 2207 remove_exclusive_swap_page(page); 2208 unlock_page(page); 2209 2210 if (write_access) { 2211 if (do_wp_page(mm, vma, address, 2212 page_table, pmd, ptl, pte) == VM_FAULT_OOM) 2213 ret = VM_FAULT_OOM; 2214 goto out; 2215 } 2216 2217 /* No need to invalidate - it was non-present before */ 2218 update_mmu_cache(vma, address, pte); 2219unlock: 2220 pte_unmap_unlock(page_table, ptl); 2221out: 2222 return ret; 2223out_nomap: 2224 pte_unmap_unlock(page_table, ptl); 2225 unlock_page(page); 2226 page_cache_release(page); 2227 return ret; 2228} 2229 2230/* 2231 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2232 * but allow concurrent faults), and pte mapped but not yet locked. 2233 * We return with mmap_sem still held, but pte unmapped and unlocked. 2234 */ 2235static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2236 unsigned long address, pte_t *page_table, pmd_t *pmd, 2237 int write_access) 2238{ 2239 struct page *page; 2240 spinlock_t *ptl; 2241 pte_t entry; 2242 2243 if (write_access) { 2244 /* Allocate our own private page. */ 2245 pte_unmap(page_table); 2246 2247 if (unlikely(anon_vma_prepare(vma))) 2248 goto oom; 2249 page = alloc_zeroed_user_highpage_movable(vma, address); 2250 if (!page) 2251 goto oom; 2252 2253 entry = mk_pte(page, vma->vm_page_prot); 2254 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2255 2256 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2257 if (!pte_none(*page_table)) 2258 goto release; 2259 inc_mm_counter(mm, anon_rss); 2260 lru_cache_add_active(page); 2261 page_add_new_anon_rmap(page, vma, address); 2262 } else { 2263 /* Map the ZERO_PAGE - vm_page_prot is readonly */ 2264 page = ZERO_PAGE(address); 2265 page_cache_get(page); 2266 entry = mk_pte(page, vma->vm_page_prot); 2267 2268 ptl = pte_lockptr(mm, pmd); 2269 spin_lock(ptl); 2270 if (!pte_none(*page_table)) 2271 goto release; 2272 inc_mm_counter(mm, file_rss); 2273 page_add_file_rmap(page); 2274 } 2275 2276 set_pte_at(mm, address, page_table, entry); 2277 2278 /* No need to invalidate - it was non-present before */ 2279 update_mmu_cache(vma, address, entry); 2280 lazy_mmu_prot_update(entry); 2281unlock: 2282 pte_unmap_unlock(page_table, ptl); 2283 return VM_FAULT_MINOR; 2284release: 2285 page_cache_release(page); 2286 goto unlock; 2287oom: 2288 return VM_FAULT_OOM; 2289} 2290 2291/* 2292 * __do_fault() tries to create a new page mapping. It aggressively 2293 * tries to share with existing pages, but makes a separate copy if 2294 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 2295 * the next page fault. 2296 * 2297 * As this is called only for pages that do not currently exist, we 2298 * do not need to flush old virtual caches or the TLB. 2299 * 2300 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2301 * but allow concurrent faults), and pte mapped but not yet locked. 2302 * We return with mmap_sem still held, but pte unmapped and unlocked. 2303 */ 2304static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2305 unsigned long address, pte_t *page_table, pmd_t *pmd, 2306 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2307{ 2308 spinlock_t *ptl; 2309 struct page *page, *faulted_page; 2310 pte_t entry; 2311 int anon = 0; 2312 struct page *dirty_page = NULL; 2313 struct fault_data fdata; 2314 2315 fdata.address = address & PAGE_MASK; 2316 fdata.pgoff = pgoff; 2317 fdata.flags = flags; 2318 2319 pte_unmap(page_table); 2320 BUG_ON(vma->vm_flags & VM_PFNMAP); 2321 2322 if (likely(vma->vm_ops->fault)) { 2323 fdata.type = -1; 2324 faulted_page = vma->vm_ops->fault(vma, &fdata); 2325 WARN_ON(fdata.type == -1); 2326 if (unlikely(!faulted_page)) 2327 return fdata.type; 2328 } else { 2329 /* Legacy ->nopage path */ 2330 fdata.type = VM_FAULT_MINOR; 2331 faulted_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, 2332 &fdata.type); 2333 /* no page was available -- either SIGBUS or OOM */ 2334 if (unlikely(faulted_page == NOPAGE_SIGBUS)) 2335 return VM_FAULT_SIGBUS; 2336 else if (unlikely(faulted_page == NOPAGE_OOM)) 2337 return VM_FAULT_OOM; 2338 } 2339 2340 /* 2341 * For consistency in subsequent calls, make the faulted_page always 2342 * locked. 2343 */ 2344 if (unlikely(!(vma->vm_flags & VM_CAN_INVALIDATE))) 2345 lock_page(faulted_page); 2346 else 2347 BUG_ON(!PageLocked(faulted_page)); 2348 2349 /* 2350 * Should we do an early C-O-W break? 2351 */ 2352 page = faulted_page; 2353 if (flags & FAULT_FLAG_WRITE) { 2354 if (!(vma->vm_flags & VM_SHARED)) { 2355 anon = 1; 2356 if (unlikely(anon_vma_prepare(vma))) { 2357 fdata.type = VM_FAULT_OOM; 2358 goto out; 2359 } 2360 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2361 if (!page) { 2362 fdata.type = VM_FAULT_OOM; 2363 goto out; 2364 } 2365 copy_user_highpage(page, faulted_page, address, vma); 2366 } else { 2367 /* 2368 * If the page will be shareable, see if the backing 2369 * address space wants to know that the page is about 2370 * to become writable 2371 */ 2372 if (vma->vm_ops->page_mkwrite && 2373 vma->vm_ops->page_mkwrite(vma, page) < 0) { 2374 fdata.type = VM_FAULT_SIGBUS; 2375 anon = 1; /* no anon but release faulted_page */ 2376 goto out; 2377 } 2378 } 2379 2380 } 2381 2382 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2383 2384 /* 2385 * This silly early PAGE_DIRTY setting removes a race 2386 * due to the bad i386 page protection. But it's valid 2387 * for other architectures too. 2388 * 2389 * Note that if write_access is true, we either now have 2390 * an exclusive copy of the page, or this is a shared mapping, 2391 * so we can make it writable and dirty to avoid having to 2392 * handle that later. 2393 */ 2394 /* Only go through if we didn't race with anybody else... */ 2395 if (likely(pte_same(*page_table, orig_pte))) { 2396 flush_icache_page(vma, page); 2397 entry = mk_pte(page, vma->vm_page_prot); 2398 if (flags & FAULT_FLAG_WRITE) 2399 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2400 set_pte_at(mm, address, page_table, entry); 2401 if (anon) { 2402 inc_mm_counter(mm, anon_rss); 2403 lru_cache_add_active(page); 2404 page_add_new_anon_rmap(page, vma, address); 2405 } else { 2406 inc_mm_counter(mm, file_rss); 2407 page_add_file_rmap(page); 2408 if (flags & FAULT_FLAG_WRITE) { 2409 dirty_page = page; 2410 get_page(dirty_page); 2411 } 2412 } 2413 2414 /* no need to invalidate: a not-present page won't be cached */ 2415 update_mmu_cache(vma, address, entry); 2416 lazy_mmu_prot_update(entry); 2417 } else { 2418 if (anon) 2419 page_cache_release(page); 2420 else 2421 anon = 1; /* no anon but release faulted_page */ 2422 } 2423 2424 pte_unmap_unlock(page_table, ptl); 2425 2426out: 2427 unlock_page(faulted_page); 2428 if (anon) 2429 page_cache_release(faulted_page); 2430 else if (dirty_page) { 2431 set_page_dirty_balance(dirty_page); 2432 put_page(dirty_page); 2433 } 2434 2435 return fdata.type; 2436} 2437 2438static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2439 unsigned long address, pte_t *page_table, pmd_t *pmd, 2440 int write_access, pte_t orig_pte) 2441{ 2442 pgoff_t pgoff = (((address & PAGE_MASK) 2443 - vma->vm_start) >> PAGE_CACHE_SHIFT) + vma->vm_pgoff; 2444 unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0); 2445 2446 return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte); 2447} 2448 2449static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2450 unsigned long address, pte_t *page_table, pmd_t *pmd, 2451 int write_access, pgoff_t pgoff, pte_t orig_pte) 2452{ 2453 unsigned int flags = FAULT_FLAG_NONLINEAR | 2454 (write_access ? FAULT_FLAG_WRITE : 0); 2455 2456 return __do_fault(mm, vma, address, page_table, pmd, pgoff, flags, orig_pte); 2457} 2458 2459/* 2460 * do_no_pfn() tries to create a new page mapping for a page without 2461 * a struct_page backing it 2462 * 2463 * As this is called only for pages that do not currently exist, we 2464 * do not need to flush old virtual caches or the TLB. 2465 * 2466 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2467 * but allow concurrent faults), and pte mapped but not yet locked. 2468 * We return with mmap_sem still held, but pte unmapped and unlocked. 2469 * 2470 * It is expected that the ->nopfn handler always returns the same pfn 2471 * for a given virtual mapping. 2472 * 2473 * Mark this `noinline' to prevent it from bloating the main pagefault code. 2474 */ 2475static noinline int do_no_pfn(struct mm_struct *mm, struct vm_area_struct *vma, 2476 unsigned long address, pte_t *page_table, pmd_t *pmd, 2477 int write_access) 2478{ 2479 spinlock_t *ptl; 2480 pte_t entry; 2481 unsigned long pfn; 2482 int ret = VM_FAULT_MINOR; 2483 2484 pte_unmap(page_table); 2485 BUG_ON(!(vma->vm_flags & VM_PFNMAP)); 2486 BUG_ON(is_cow_mapping(vma->vm_flags)); 2487 2488 pfn = vma->vm_ops->nopfn(vma, address & PAGE_MASK); 2489 if (unlikely(pfn == NOPFN_OOM)) 2490 return VM_FAULT_OOM; 2491 else if (unlikely(pfn == NOPFN_SIGBUS)) 2492 return VM_FAULT_SIGBUS; 2493 else if (unlikely(pfn == NOPFN_REFAULT)) 2494 return VM_FAULT_MINOR; 2495 2496 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2497 2498 /* Only go through if we didn't race with anybody else... */ 2499 if (pte_none(*page_table)) { 2500 entry = pfn_pte(pfn, vma->vm_page_prot); 2501 if (write_access) 2502 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2503 set_pte_at(mm, address, page_table, entry); 2504 } 2505 pte_unmap_unlock(page_table, ptl); 2506 return ret; 2507} 2508 2509/* 2510 * Fault of a previously existing named mapping. Repopulate the pte 2511 * from the encoded file_pte if possible. This enables swappable 2512 * nonlinear vmas. 2513 * 2514 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2515 * but allow concurrent faults), and pte mapped but not yet locked. 2516 * We return with mmap_sem still held, but pte unmapped and unlocked. 2517 */ 2518static int do_file_page(struct mm_struct *mm, struct vm_area_struct *vma, 2519 unsigned long address, pte_t *page_table, pmd_t *pmd, 2520 int write_access, pte_t orig_pte) 2521{ 2522 pgoff_t pgoff; 2523 int err; 2524 2525 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2526 return VM_FAULT_MINOR; 2527 2528 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 2529 /* 2530 * Page table corrupted: show pte and kill process. 2531 */ 2532 print_bad_pte(vma, orig_pte, address); 2533 return VM_FAULT_OOM; 2534 } 2535 2536 pgoff = pte_to_pgoff(orig_pte); 2537 2538 if (vma->vm_ops && vma->vm_ops->fault) 2539 return do_nonlinear_fault(mm, vma, address, page_table, pmd, 2540 write_access, pgoff, orig_pte); 2541 2542 /* We can then assume vm->vm_ops && vma->vm_ops->populate */ 2543 err = vma->vm_ops->populate(vma, address & PAGE_MASK, PAGE_SIZE, 2544 vma->vm_page_prot, pgoff, 0); 2545 if (err == -ENOMEM) 2546 return VM_FAULT_OOM; 2547 if (err) 2548 return VM_FAULT_SIGBUS; 2549 return VM_FAULT_MAJOR; 2550} 2551 2552/* 2553 * These routines also need to handle stuff like marking pages dirty 2554 * and/or accessed for architectures that don't do it in hardware (most 2555 * RISC architectures). The early dirtying is also good on the i386. 2556 * 2557 * There is also a hook called "update_mmu_cache()" that architectures 2558 * with external mmu caches can use to update those (ie the Sparc or 2559 * PowerPC hashed page tables that act as extended TLBs). 2560 * 2561 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2562 * but allow concurrent faults), and pte mapped but not yet locked. 2563 * We return with mmap_sem still held, but pte unmapped and unlocked. 2564 */ 2565static inline int handle_pte_fault(struct mm_struct *mm, 2566 struct vm_area_struct *vma, unsigned long address, 2567 pte_t *pte, pmd_t *pmd, int write_access) 2568{ 2569 pte_t entry; 2570 spinlock_t *ptl; 2571 2572 entry = *pte; 2573 if (!pte_present(entry)) { 2574 if (pte_none(entry)) { 2575 if (vma->vm_ops) { 2576 if (vma->vm_ops->fault || vma->vm_ops->nopage) 2577 return do_linear_fault(mm, vma, address, 2578 pte, pmd, write_access, entry); 2579 if (unlikely(vma->vm_ops->nopfn)) 2580 return do_no_pfn(mm, vma, address, pte, 2581 pmd, write_access); 2582 } 2583 return do_anonymous_page(mm, vma, address, 2584 pte, pmd, write_access); 2585 } 2586 if (pte_file(entry)) 2587 return do_file_page(mm, vma, address, 2588 pte, pmd, write_access, entry); 2589 return do_swap_page(mm, vma, address, 2590 pte, pmd, write_access, entry); 2591 } 2592 2593 ptl = pte_lockptr(mm, pmd); 2594 spin_lock(ptl); 2595 if (unlikely(!pte_same(*pte, entry))) 2596 goto unlock; 2597 if (write_access) { 2598 if (!pte_write(entry)) 2599 return do_wp_page(mm, vma, address, 2600 pte, pmd, ptl, entry); 2601 entry = pte_mkdirty(entry); 2602 } 2603 entry = pte_mkyoung(entry); 2604 if (ptep_set_access_flags(vma, address, pte, entry, write_access)) { 2605 update_mmu_cache(vma, address, entry); 2606 lazy_mmu_prot_update(entry); 2607 } else { 2608 /* 2609 * This is needed only for protection faults but the arch code 2610 * is not yet telling us if this is a protection fault or not. 2611 * This still avoids useless tlb flushes for .text page faults 2612 * with threads. 2613 */ 2614 if (write_access) 2615 flush_tlb_page(vma, address); 2616 } 2617unlock: 2618 pte_unmap_unlock(pte, ptl); 2619 return VM_FAULT_MINOR; 2620} 2621 2622/* 2623 * By the time we get here, we already hold the mm semaphore 2624 */ 2625int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2626 unsigned long address, int write_access) 2627{ 2628 pgd_t *pgd; 2629 pud_t *pud; 2630 pmd_t *pmd; 2631 pte_t *pte; 2632 2633 __set_current_state(TASK_RUNNING); 2634 2635 count_vm_event(PGFAULT); 2636 2637 if (unlikely(is_vm_hugetlb_page(vma))) 2638 return hugetlb_fault(mm, vma, address, write_access); 2639 2640 pgd = pgd_offset(mm, address); 2641 pud = pud_alloc(mm, pgd, address); 2642 if (!pud) 2643 return VM_FAULT_OOM; 2644 pmd = pmd_alloc(mm, pud, address); 2645 if (!pmd) 2646 return VM_FAULT_OOM; 2647 pte = pte_alloc_map(mm, pmd, address); 2648 if (!pte) 2649 return VM_FAULT_OOM; 2650 2651 return handle_pte_fault(mm, vma, address, pte, pmd, write_access); 2652} 2653 2654EXPORT_SYMBOL_GPL(__handle_mm_fault); 2655 2656#ifndef __PAGETABLE_PUD_FOLDED 2657/* 2658 * Allocate page upper directory. 2659 * We've already handled the fast-path in-line. 2660 */ 2661int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 2662{ 2663 pud_t *new = pud_alloc_one(mm, address); 2664 if (!new) 2665 return -ENOMEM; 2666 2667 spin_lock(&mm->page_table_lock); 2668 if (pgd_present(*pgd)) /* Another has populated it */ 2669 pud_free(new); 2670 else 2671 pgd_populate(mm, pgd, new); 2672 spin_unlock(&mm->page_table_lock); 2673 return 0; 2674} 2675#endif /* __PAGETABLE_PUD_FOLDED */ 2676 2677#ifndef __PAGETABLE_PMD_FOLDED 2678/* 2679 * Allocate page middle directory. 2680 * We've already handled the fast-path in-line. 2681 */ 2682int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 2683{ 2684 pmd_t *new = pmd_alloc_one(mm, address); 2685 if (!new) 2686 return -ENOMEM; 2687 2688 spin_lock(&mm->page_table_lock); 2689#ifndef __ARCH_HAS_4LEVEL_HACK 2690 if (pud_present(*pud)) /* Another has populated it */ 2691 pmd_free(new); 2692 else 2693 pud_populate(mm, pud, new); 2694#else 2695 if (pgd_present(*pud)) /* Another has populated it */ 2696 pmd_free(new); 2697 else 2698 pgd_populate(mm, pud, new); 2699#endif /* __ARCH_HAS_4LEVEL_HACK */ 2700 spin_unlock(&mm->page_table_lock); 2701 return 0; 2702} 2703#endif /* __PAGETABLE_PMD_FOLDED */ 2704 2705int make_pages_present(unsigned long addr, unsigned long end) 2706{ 2707 int ret, len, write; 2708 struct vm_area_struct * vma; 2709 2710 vma = find_vma(current->mm, addr); 2711 if (!vma) 2712 return -1; 2713 write = (vma->vm_flags & VM_WRITE) != 0; 2714 BUG_ON(addr >= end); 2715 BUG_ON(end > vma->vm_end); 2716 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; 2717 ret = get_user_pages(current, current->mm, addr, 2718 len, write, 0, NULL, NULL); 2719 if (ret < 0) 2720 return ret; 2721 return ret == len ? 0 : -1; 2722} 2723 2724/* 2725 * Map a vmalloc()-space virtual address to the physical page. 2726 */ 2727struct page * vmalloc_to_page(void * vmalloc_addr) 2728{ 2729 unsigned long addr = (unsigned long) vmalloc_addr; 2730 struct page *page = NULL; 2731 pgd_t *pgd = pgd_offset_k(addr); 2732 pud_t *pud; 2733 pmd_t *pmd; 2734 pte_t *ptep, pte; 2735 2736 if (!pgd_none(*pgd)) { 2737 pud = pud_offset(pgd, addr); 2738 if (!pud_none(*pud)) { 2739 pmd = pmd_offset(pud, addr); 2740 if (!pmd_none(*pmd)) { 2741 ptep = pte_offset_map(pmd, addr); 2742 pte = *ptep; 2743 if (pte_present(pte)) 2744 page = pte_page(pte); 2745 pte_unmap(ptep); 2746 } 2747 } 2748 } 2749 return page; 2750} 2751 2752EXPORT_SYMBOL(vmalloc_to_page); 2753 2754/* 2755 * Map a vmalloc()-space virtual address to the physical page frame number. 2756 */ 2757unsigned long vmalloc_to_pfn(void * vmalloc_addr) 2758{ 2759 return page_to_pfn(vmalloc_to_page(vmalloc_addr)); 2760} 2761 2762EXPORT_SYMBOL(vmalloc_to_pfn); 2763 2764#if !defined(__HAVE_ARCH_GATE_AREA) 2765 2766#if defined(AT_SYSINFO_EHDR) 2767static struct vm_area_struct gate_vma; 2768 2769static int __init gate_vma_init(void) 2770{ 2771 gate_vma.vm_mm = NULL; 2772 gate_vma.vm_start = FIXADDR_USER_START; 2773 gate_vma.vm_end = FIXADDR_USER_END; 2774 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 2775 gate_vma.vm_page_prot = __P101; 2776 /* 2777 * Make sure the vDSO gets into every core dump. 2778 * Dumping its contents makes post-mortem fully interpretable later 2779 * without matching up the same kernel and hardware config to see 2780 * what PC values meant. 2781 */ 2782 gate_vma.vm_flags |= VM_ALWAYSDUMP; 2783 return 0; 2784} 2785__initcall(gate_vma_init); 2786#endif 2787 2788struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 2789{ 2790#ifdef AT_SYSINFO_EHDR 2791 return &gate_vma; 2792#else 2793 return NULL; 2794#endif 2795} 2796 2797int in_gate_area_no_task(unsigned long addr) 2798{ 2799#ifdef AT_SYSINFO_EHDR 2800 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 2801 return 1; 2802#endif 2803 return 0; 2804} 2805 2806#endif /* __HAVE_ARCH_GATE_AREA */ 2807 2808/* 2809 * Access another process' address space. 2810 * Source/target buffer must be kernel space, 2811 * Do not walk the page table directly, use get_user_pages 2812 */ 2813int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2814{ 2815 struct mm_struct *mm; 2816 struct vm_area_struct *vma; 2817 struct page *page; 2818 void *old_buf = buf; 2819 2820 mm = get_task_mm(tsk); 2821 if (!mm) 2822 return 0; 2823 2824 down_read(&mm->mmap_sem); 2825 /* ignore errors, just check how much was sucessfully transfered */ 2826 while (len) { 2827 int bytes, ret, offset; 2828 void *maddr; 2829 2830 ret = get_user_pages(tsk, mm, addr, 1, 2831 write, 1, &page, &vma); 2832 if (ret <= 0) 2833 break; 2834 2835 bytes = len; 2836 offset = addr & (PAGE_SIZE-1); 2837 if (bytes > PAGE_SIZE-offset) 2838 bytes = PAGE_SIZE-offset; 2839 2840 maddr = kmap(page); 2841 if (write) { 2842 copy_to_user_page(vma, page, addr, 2843 maddr + offset, buf, bytes); 2844 set_page_dirty_lock(page); 2845 } else { 2846 copy_from_user_page(vma, page, addr, 2847 buf, maddr + offset, bytes); 2848 } 2849 kunmap(page); 2850 page_cache_release(page); 2851 len -= bytes; 2852 buf += bytes; 2853 addr += bytes; 2854 } 2855 up_read(&mm->mmap_sem); 2856 mmput(mm); 2857 2858 return buf - old_buf; 2859} 2860