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/ksm.h> 49 #include <linux/rmap.h> 50 #include <linux/module.h> 51 #include <linux/delayacct.h> 52 #include <linux/init.h> 53 #include <linux/writeback.h> 54 #include <linux/memcontrol.h> 55 #include <linux/mmu_notifier.h> 56 #include <linux/kallsyms.h> 57 #include <linux/swapops.h> 58 #include <linux/elf.h> 59 60 #include <asm/io.h> 61 #include <asm/pgalloc.h> 62 #include <asm/uaccess.h> 63 #include <asm/tlb.h> 64 #include <asm/tlbflush.h> 65 #include <asm/pgtable.h> 66 67 #include "internal.h" 68 69 #ifndef CONFIG_NEED_MULTIPLE_NODES 70 /* use the per-pgdat data instead for discontigmem - mbligh */ 71 unsigned long max_mapnr; 72 struct page *mem_map; 73 74 EXPORT_SYMBOL(max_mapnr); 75 EXPORT_SYMBOL(mem_map); 76 #endif 77 78 unsigned long num_physpages; 79 /* 80 * A number of key systems in x86 including ioremap() rely on the assumption 81 * that high_memory defines the upper bound on direct map memory, then end 82 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 83 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 84 * and ZONE_HIGHMEM. 85 */ 86 void * high_memory; 87 88 EXPORT_SYMBOL(num_physpages); 89 EXPORT_SYMBOL(high_memory); 90 91 /* 92 * Randomize the address space (stacks, mmaps, brk, etc.). 93 * 94 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 95 * as ancient (libc5 based) binaries can segfault. ) 96 */ 97 int randomize_va_space __read_mostly = 98 #ifdef CONFIG_COMPAT_BRK 99 1; 100 #else 101 2; 102 #endif 103 104 static int __init disable_randmaps(char *s) 105 { 106 randomize_va_space = 0; 107 return 1; 108 } 109 __setup("norandmaps", disable_randmaps); 110 111 unsigned long zero_pfn __read_mostly; 112 unsigned long highest_memmap_pfn __read_mostly; 113 114 /* 115 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init() 116 */ 117 static int __init init_zero_pfn(void) 118 { 119 zero_pfn = page_to_pfn(ZERO_PAGE(0)); 120 return 0; 121 } 122 core_initcall(init_zero_pfn); 123 124 /* 125 * If a p?d_bad entry is found while walking page tables, report 126 * the error, before resetting entry to p?d_none. Usually (but 127 * very seldom) called out from the p?d_none_or_clear_bad macros. 128 */ 129 130 void pgd_clear_bad(pgd_t *pgd) 131 { 132 pgd_ERROR(*pgd); 133 pgd_clear(pgd); 134 } 135 136 void pud_clear_bad(pud_t *pud) 137 { 138 pud_ERROR(*pud); 139 pud_clear(pud); 140 } 141 142 void pmd_clear_bad(pmd_t *pmd) 143 { 144 pmd_ERROR(*pmd); 145 pmd_clear(pmd); 146 } 147 148 /* 149 * Note: this doesn't free the actual pages themselves. That 150 * has been handled earlier when unmapping all the memory regions. 151 */ 152 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 153 unsigned long addr) 154 { 155 pgtable_t token = pmd_pgtable(*pmd); 156 pmd_clear(pmd); 157 pte_free_tlb(tlb, token, addr); 158 tlb->mm->nr_ptes--; 159 } 160 161 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 162 unsigned long addr, unsigned long end, 163 unsigned long floor, unsigned long ceiling) 164 { 165 pmd_t *pmd; 166 unsigned long next; 167 unsigned long start; 168 169 start = addr; 170 pmd = pmd_offset(pud, addr); 171 do { 172 next = pmd_addr_end(addr, end); 173 if (pmd_none_or_clear_bad(pmd)) 174 continue; 175 free_pte_range(tlb, pmd, addr); 176 } while (pmd++, addr = next, addr != end); 177 178 start &= PUD_MASK; 179 if (start < floor) 180 return; 181 if (ceiling) { 182 ceiling &= PUD_MASK; 183 if (!ceiling) 184 return; 185 } 186 if (end - 1 > ceiling - 1) 187 return; 188 189 pmd = pmd_offset(pud, start); 190 pud_clear(pud); 191 pmd_free_tlb(tlb, pmd, start); 192 } 193 194 static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 195 unsigned long addr, unsigned long end, 196 unsigned long floor, unsigned long ceiling) 197 { 198 pud_t *pud; 199 unsigned long next; 200 unsigned long start; 201 202 start = addr; 203 pud = pud_offset(pgd, addr); 204 do { 205 next = pud_addr_end(addr, end); 206 if (pud_none_or_clear_bad(pud)) 207 continue; 208 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 209 } while (pud++, addr = next, addr != end); 210 211 start &= PGDIR_MASK; 212 if (start < floor) 213 return; 214 if (ceiling) { 215 ceiling &= PGDIR_MASK; 216 if (!ceiling) 217 return; 218 } 219 if (end - 1 > ceiling - 1) 220 return; 221 222 pud = pud_offset(pgd, start); 223 pgd_clear(pgd); 224 pud_free_tlb(tlb, pud, start); 225 } 226 227 /* 228 * This function frees user-level page tables of a process. 229 * 230 * Must be called with pagetable lock held. 231 */ 232 void free_pgd_range(struct mmu_gather *tlb, 233 unsigned long addr, unsigned long end, 234 unsigned long floor, unsigned long ceiling) 235 { 236 pgd_t *pgd; 237 unsigned long next; 238 unsigned long start; 239 240 /* 241 * The next few lines have given us lots of grief... 242 * 243 * Why are we testing PMD* at this top level? Because often 244 * there will be no work to do at all, and we'd prefer not to 245 * go all the way down to the bottom just to discover that. 246 * 247 * Why all these "- 1"s? Because 0 represents both the bottom 248 * of the address space and the top of it (using -1 for the 249 * top wouldn't help much: the masks would do the wrong thing). 250 * The rule is that addr 0 and floor 0 refer to the bottom of 251 * the address space, but end 0 and ceiling 0 refer to the top 252 * Comparisons need to use "end - 1" and "ceiling - 1" (though 253 * that end 0 case should be mythical). 254 * 255 * Wherever addr is brought up or ceiling brought down, we must 256 * be careful to reject "the opposite 0" before it confuses the 257 * subsequent tests. But what about where end is brought down 258 * by PMD_SIZE below? no, end can't go down to 0 there. 259 * 260 * Whereas we round start (addr) and ceiling down, by different 261 * masks at different levels, in order to test whether a table 262 * now has no other vmas using it, so can be freed, we don't 263 * bother to round floor or end up - the tests don't need that. 264 */ 265 266 addr &= PMD_MASK; 267 if (addr < floor) { 268 addr += PMD_SIZE; 269 if (!addr) 270 return; 271 } 272 if (ceiling) { 273 ceiling &= PMD_MASK; 274 if (!ceiling) 275 return; 276 } 277 if (end - 1 > ceiling - 1) 278 end -= PMD_SIZE; 279 if (addr > end - 1) 280 return; 281 282 start = addr; 283 pgd = pgd_offset(tlb->mm, addr); 284 do { 285 next = pgd_addr_end(addr, end); 286 if (pgd_none_or_clear_bad(pgd)) 287 continue; 288 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 289 } while (pgd++, addr = next, addr != end); 290 } 291 292 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 293 unsigned long floor, unsigned long ceiling) 294 { 295 while (vma) { 296 struct vm_area_struct *next = vma->vm_next; 297 unsigned long addr = vma->vm_start; 298 299 /* 300 * Hide vma from rmap and truncate_pagecache before freeing 301 * pgtables 302 */ 303 anon_vma_unlink(vma); 304 unlink_file_vma(vma); 305 306 if (is_vm_hugetlb_page(vma)) { 307 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 308 floor, next? next->vm_start: ceiling); 309 } else { 310 /* 311 * Optimization: gather nearby vmas into one call down 312 */ 313 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 314 && !is_vm_hugetlb_page(next)) { 315 vma = next; 316 next = vma->vm_next; 317 anon_vma_unlink(vma); 318 unlink_file_vma(vma); 319 } 320 free_pgd_range(tlb, addr, vma->vm_end, 321 floor, next? next->vm_start: ceiling); 322 } 323 vma = next; 324 } 325 } 326 327 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 328 { 329 pgtable_t new = pte_alloc_one(mm, address); 330 if (!new) 331 return -ENOMEM; 332 333 /* 334 * Ensure all pte setup (eg. pte page lock and page clearing) are 335 * visible before the pte is made visible to other CPUs by being 336 * put into page tables. 337 * 338 * The other side of the story is the pointer chasing in the page 339 * table walking code (when walking the page table without locking; 340 * ie. most of the time). Fortunately, these data accesses consist 341 * of a chain of data-dependent loads, meaning most CPUs (alpha 342 * being the notable exception) will already guarantee loads are 343 * seen in-order. See the alpha page table accessors for the 344 * smp_read_barrier_depends() barriers in page table walking code. 345 */ 346 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 347 348 spin_lock(&mm->page_table_lock); 349 if (!pmd_present(*pmd)) { /* Has another populated it ? */ 350 mm->nr_ptes++; 351 pmd_populate(mm, pmd, new); 352 new = NULL; 353 } 354 spin_unlock(&mm->page_table_lock); 355 if (new) 356 pte_free(mm, new); 357 return 0; 358 } 359 360 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 361 { 362 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 363 if (!new) 364 return -ENOMEM; 365 366 smp_wmb(); /* See comment in __pte_alloc */ 367 368 spin_lock(&init_mm.page_table_lock); 369 if (!pmd_present(*pmd)) { /* Has another populated it ? */ 370 pmd_populate_kernel(&init_mm, pmd, new); 371 new = NULL; 372 } 373 spin_unlock(&init_mm.page_table_lock); 374 if (new) 375 pte_free_kernel(&init_mm, new); 376 return 0; 377 } 378 379 static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) 380 { 381 if (file_rss) 382 add_mm_counter(mm, file_rss, file_rss); 383 if (anon_rss) 384 add_mm_counter(mm, anon_rss, anon_rss); 385 } 386 387 /* 388 * This function is called to print an error when a bad pte 389 * is found. For example, we might have a PFN-mapped pte in 390 * a region that doesn't allow it. 391 * 392 * The calling function must still handle the error. 393 */ 394 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 395 pte_t pte, struct page *page) 396 { 397 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 398 pud_t *pud = pud_offset(pgd, addr); 399 pmd_t *pmd = pmd_offset(pud, addr); 400 struct address_space *mapping; 401 pgoff_t index; 402 static unsigned long resume; 403 static unsigned long nr_shown; 404 static unsigned long nr_unshown; 405 406 /* 407 * Allow a burst of 60 reports, then keep quiet for that minute; 408 * or allow a steady drip of one report per second. 409 */ 410 if (nr_shown == 60) { 411 if (time_before(jiffies, resume)) { 412 nr_unshown++; 413 return; 414 } 415 if (nr_unshown) { 416 printk(KERN_ALERT 417 "BUG: Bad page map: %lu messages suppressed\n", 418 nr_unshown); 419 nr_unshown = 0; 420 } 421 nr_shown = 0; 422 } 423 if (nr_shown++ == 0) 424 resume = jiffies + 60 * HZ; 425 426 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 427 index = linear_page_index(vma, addr); 428 429 printk(KERN_ALERT 430 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 431 current->comm, 432 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 433 if (page) { 434 printk(KERN_ALERT 435 "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n", 436 page, (void *)page->flags, page_count(page), 437 page_mapcount(page), page->mapping, page->index); 438 } 439 printk(KERN_ALERT 440 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 441 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 442 /* 443 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 444 */ 445 if (vma->vm_ops) 446 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n", 447 (unsigned long)vma->vm_ops->fault); 448 if (vma->vm_file && vma->vm_file->f_op) 449 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n", 450 (unsigned long)vma->vm_file->f_op->mmap); 451 dump_stack(); 452 add_taint(TAINT_BAD_PAGE); 453 } 454 455 static inline int is_cow_mapping(unsigned int flags) 456 { 457 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 458 } 459 460 #ifndef is_zero_pfn 461 static inline int is_zero_pfn(unsigned long pfn) 462 { 463 return pfn == zero_pfn; 464 } 465 #endif 466 467 #ifndef my_zero_pfn 468 static inline unsigned long my_zero_pfn(unsigned long addr) 469 { 470 return zero_pfn; 471 } 472 #endif 473 474 /* 475 * vm_normal_page -- This function gets the "struct page" associated with a pte. 476 * 477 * "Special" mappings do not wish to be associated with a "struct page" (either 478 * it doesn't exist, or it exists but they don't want to touch it). In this 479 * case, NULL is returned here. "Normal" mappings do have a struct page. 480 * 481 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 482 * pte bit, in which case this function is trivial. Secondly, an architecture 483 * may not have a spare pte bit, which requires a more complicated scheme, 484 * described below. 485 * 486 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 487 * special mapping (even if there are underlying and valid "struct pages"). 488 * COWed pages of a VM_PFNMAP are always normal. 489 * 490 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 491 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 492 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 493 * mapping will always honor the rule 494 * 495 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 496 * 497 * And for normal mappings this is false. 498 * 499 * This restricts such mappings to be a linear translation from virtual address 500 * to pfn. To get around this restriction, we allow arbitrary mappings so long 501 * as the vma is not a COW mapping; in that case, we know that all ptes are 502 * special (because none can have been COWed). 503 * 504 * 505 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 506 * 507 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 508 * page" backing, however the difference is that _all_ pages with a struct 509 * page (that is, those where pfn_valid is true) are refcounted and considered 510 * normal pages by the VM. The disadvantage is that pages are refcounted 511 * (which can be slower and simply not an option for some PFNMAP users). The 512 * advantage is that we don't have to follow the strict linearity rule of 513 * PFNMAP mappings in order to support COWable mappings. 514 * 515 */ 516 #ifdef __HAVE_ARCH_PTE_SPECIAL 517 # define HAVE_PTE_SPECIAL 1 518 #else 519 # define HAVE_PTE_SPECIAL 0 520 #endif 521 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 522 pte_t pte) 523 { 524 unsigned long pfn = pte_pfn(pte); 525 526 if (HAVE_PTE_SPECIAL) { 527 if (likely(!pte_special(pte))) 528 goto check_pfn; 529 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP)) 530 return NULL; 531 if (!is_zero_pfn(pfn)) 532 print_bad_pte(vma, addr, pte, NULL); 533 return NULL; 534 } 535 536 /* !HAVE_PTE_SPECIAL case follows: */ 537 538 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 539 if (vma->vm_flags & VM_MIXEDMAP) { 540 if (!pfn_valid(pfn)) 541 return NULL; 542 goto out; 543 } else { 544 unsigned long off; 545 off = (addr - vma->vm_start) >> PAGE_SHIFT; 546 if (pfn == vma->vm_pgoff + off) 547 return NULL; 548 if (!is_cow_mapping(vma->vm_flags)) 549 return NULL; 550 } 551 } 552 553 if (is_zero_pfn(pfn)) 554 return NULL; 555 check_pfn: 556 if (unlikely(pfn > highest_memmap_pfn)) { 557 print_bad_pte(vma, addr, pte, NULL); 558 return NULL; 559 } 560 561 /* 562 * NOTE! We still have PageReserved() pages in the page tables. 563 * eg. VDSO mappings can cause them to exist. 564 */ 565 out: 566 return pfn_to_page(pfn); 567 } 568 569 /* 570 * copy one vm_area from one task to the other. Assumes the page tables 571 * already present in the new task to be cleared in the whole range 572 * covered by this vma. 573 */ 574 575 static inline unsigned long 576 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 577 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 578 unsigned long addr, int *rss) 579 { 580 unsigned long vm_flags = vma->vm_flags; 581 pte_t pte = *src_pte; 582 struct page *page; 583 584 /* pte contains position in swap or file, so copy. */ 585 if (unlikely(!pte_present(pte))) { 586 if (!pte_file(pte)) { 587 swp_entry_t entry = pte_to_swp_entry(pte); 588 589 if (swap_duplicate(entry) < 0) 590 return entry.val; 591 592 /* make sure dst_mm is on swapoff's mmlist. */ 593 if (unlikely(list_empty(&dst_mm->mmlist))) { 594 spin_lock(&mmlist_lock); 595 if (list_empty(&dst_mm->mmlist)) 596 list_add(&dst_mm->mmlist, 597 &src_mm->mmlist); 598 spin_unlock(&mmlist_lock); 599 } 600 if (is_write_migration_entry(entry) && 601 is_cow_mapping(vm_flags)) { 602 /* 603 * COW mappings require pages in both parent 604 * and child to be set to read. 605 */ 606 make_migration_entry_read(&entry); 607 pte = swp_entry_to_pte(entry); 608 set_pte_at(src_mm, addr, src_pte, pte); 609 } 610 } 611 goto out_set_pte; 612 } 613 614 /* 615 * If it's a COW mapping, write protect it both 616 * in the parent and the child 617 */ 618 if (is_cow_mapping(vm_flags)) { 619 ptep_set_wrprotect(src_mm, addr, src_pte); 620 pte = pte_wrprotect(pte); 621 } 622 623 /* 624 * If it's a shared mapping, mark it clean in 625 * the child 626 */ 627 if (vm_flags & VM_SHARED) 628 pte = pte_mkclean(pte); 629 pte = pte_mkold(pte); 630 631 page = vm_normal_page(vma, addr, pte); 632 if (page) { 633 get_page(page); 634 page_dup_rmap(page); 635 rss[PageAnon(page)]++; 636 } 637 638 out_set_pte: 639 set_pte_at(dst_mm, addr, dst_pte, pte); 640 return 0; 641 } 642 643 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 644 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 645 unsigned long addr, unsigned long end) 646 { 647 pte_t *orig_src_pte, *orig_dst_pte; 648 pte_t *src_pte, *dst_pte; 649 spinlock_t *src_ptl, *dst_ptl; 650 int progress = 0; 651 int rss[2]; 652 swp_entry_t entry = (swp_entry_t){0}; 653 654 again: 655 rss[1] = rss[0] = 0; 656 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 657 if (!dst_pte) 658 return -ENOMEM; 659 src_pte = pte_offset_map_nested(src_pmd, addr); 660 src_ptl = pte_lockptr(src_mm, src_pmd); 661 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 662 orig_src_pte = src_pte; 663 orig_dst_pte = dst_pte; 664 arch_enter_lazy_mmu_mode(); 665 666 do { 667 /* 668 * We are holding two locks at this point - either of them 669 * could generate latencies in another task on another CPU. 670 */ 671 if (progress >= 32) { 672 progress = 0; 673 if (need_resched() || 674 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 675 break; 676 } 677 if (pte_none(*src_pte)) { 678 progress++; 679 continue; 680 } 681 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, 682 vma, addr, rss); 683 if (entry.val) 684 break; 685 progress += 8; 686 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 687 688 arch_leave_lazy_mmu_mode(); 689 spin_unlock(src_ptl); 690 pte_unmap_nested(orig_src_pte); 691 add_mm_rss(dst_mm, rss[0], rss[1]); 692 pte_unmap_unlock(orig_dst_pte, dst_ptl); 693 cond_resched(); 694 695 if (entry.val) { 696 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) 697 return -ENOMEM; 698 progress = 0; 699 } 700 if (addr != end) 701 goto again; 702 return 0; 703 } 704 705 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 706 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 707 unsigned long addr, unsigned long end) 708 { 709 pmd_t *src_pmd, *dst_pmd; 710 unsigned long next; 711 712 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 713 if (!dst_pmd) 714 return -ENOMEM; 715 src_pmd = pmd_offset(src_pud, addr); 716 do { 717 next = pmd_addr_end(addr, end); 718 if (pmd_none_or_clear_bad(src_pmd)) 719 continue; 720 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 721 vma, addr, next)) 722 return -ENOMEM; 723 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 724 return 0; 725 } 726 727 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 728 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 729 unsigned long addr, unsigned long end) 730 { 731 pud_t *src_pud, *dst_pud; 732 unsigned long next; 733 734 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 735 if (!dst_pud) 736 return -ENOMEM; 737 src_pud = pud_offset(src_pgd, addr); 738 do { 739 next = pud_addr_end(addr, end); 740 if (pud_none_or_clear_bad(src_pud)) 741 continue; 742 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 743 vma, addr, next)) 744 return -ENOMEM; 745 } while (dst_pud++, src_pud++, addr = next, addr != end); 746 return 0; 747 } 748 749 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 750 struct vm_area_struct *vma) 751 { 752 pgd_t *src_pgd, *dst_pgd; 753 unsigned long next; 754 unsigned long addr = vma->vm_start; 755 unsigned long end = vma->vm_end; 756 int ret; 757 758 /* 759 * Don't copy ptes where a page fault will fill them correctly. 760 * Fork becomes much lighter when there are big shared or private 761 * readonly mappings. The tradeoff is that copy_page_range is more 762 * efficient than faulting. 763 */ 764 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 765 if (!vma->anon_vma) 766 return 0; 767 } 768 769 if (is_vm_hugetlb_page(vma)) 770 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 771 772 if (unlikely(is_pfn_mapping(vma))) { 773 /* 774 * We do not free on error cases below as remove_vma 775 * gets called on error from higher level routine 776 */ 777 ret = track_pfn_vma_copy(vma); 778 if (ret) 779 return ret; 780 } 781 782 /* 783 * We need to invalidate the secondary MMU mappings only when 784 * there could be a permission downgrade on the ptes of the 785 * parent mm. And a permission downgrade will only happen if 786 * is_cow_mapping() returns true. 787 */ 788 if (is_cow_mapping(vma->vm_flags)) 789 mmu_notifier_invalidate_range_start(src_mm, addr, end); 790 791 ret = 0; 792 dst_pgd = pgd_offset(dst_mm, addr); 793 src_pgd = pgd_offset(src_mm, addr); 794 do { 795 next = pgd_addr_end(addr, end); 796 if (pgd_none_or_clear_bad(src_pgd)) 797 continue; 798 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 799 vma, addr, next))) { 800 ret = -ENOMEM; 801 break; 802 } 803 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 804 805 if (is_cow_mapping(vma->vm_flags)) 806 mmu_notifier_invalidate_range_end(src_mm, 807 vma->vm_start, end); 808 return ret; 809 } 810 811 static unsigned long zap_pte_range(struct mmu_gather *tlb, 812 struct vm_area_struct *vma, pmd_t *pmd, 813 unsigned long addr, unsigned long end, 814 long *zap_work, struct zap_details *details) 815 { 816 struct mm_struct *mm = tlb->mm; 817 pte_t *pte; 818 spinlock_t *ptl; 819 int file_rss = 0; 820 int anon_rss = 0; 821 822 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 823 arch_enter_lazy_mmu_mode(); 824 do { 825 pte_t ptent = *pte; 826 if (pte_none(ptent)) { 827 (*zap_work)--; 828 continue; 829 } 830 831 (*zap_work) -= PAGE_SIZE; 832 833 if (pte_present(ptent)) { 834 struct page *page; 835 836 page = vm_normal_page(vma, addr, ptent); 837 if (unlikely(details) && page) { 838 /* 839 * unmap_shared_mapping_pages() wants to 840 * invalidate cache without truncating: 841 * unmap shared but keep private pages. 842 */ 843 if (details->check_mapping && 844 details->check_mapping != page->mapping) 845 continue; 846 /* 847 * Each page->index must be checked when 848 * invalidating or truncating nonlinear. 849 */ 850 if (details->nonlinear_vma && 851 (page->index < details->first_index || 852 page->index > details->last_index)) 853 continue; 854 } 855 ptent = ptep_get_and_clear_full(mm, addr, pte, 856 tlb->fullmm); 857 tlb_remove_tlb_entry(tlb, pte, addr); 858 if (unlikely(!page)) 859 continue; 860 if (unlikely(details) && details->nonlinear_vma 861 && linear_page_index(details->nonlinear_vma, 862 addr) != page->index) 863 set_pte_at(mm, addr, pte, 864 pgoff_to_pte(page->index)); 865 if (PageAnon(page)) 866 anon_rss--; 867 else { 868 if (pte_dirty(ptent)) 869 set_page_dirty(page); 870 if (pte_young(ptent) && 871 likely(!VM_SequentialReadHint(vma))) 872 mark_page_accessed(page); 873 file_rss--; 874 } 875 page_remove_rmap(page); 876 if (unlikely(page_mapcount(page) < 0)) 877 print_bad_pte(vma, addr, ptent, page); 878 tlb_remove_page(tlb, page); 879 continue; 880 } 881 /* 882 * If details->check_mapping, we leave swap entries; 883 * if details->nonlinear_vma, we leave file entries. 884 */ 885 if (unlikely(details)) 886 continue; 887 if (pte_file(ptent)) { 888 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 889 print_bad_pte(vma, addr, ptent, NULL); 890 } else if 891 (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent)))) 892 print_bad_pte(vma, addr, ptent, NULL); 893 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 894 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 895 896 add_mm_rss(mm, file_rss, anon_rss); 897 arch_leave_lazy_mmu_mode(); 898 pte_unmap_unlock(pte - 1, ptl); 899 900 return addr; 901 } 902 903 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 904 struct vm_area_struct *vma, pud_t *pud, 905 unsigned long addr, unsigned long end, 906 long *zap_work, struct zap_details *details) 907 { 908 pmd_t *pmd; 909 unsigned long next; 910 911 pmd = pmd_offset(pud, addr); 912 do { 913 next = pmd_addr_end(addr, end); 914 if (pmd_none_or_clear_bad(pmd)) { 915 (*zap_work)--; 916 continue; 917 } 918 next = zap_pte_range(tlb, vma, pmd, addr, next, 919 zap_work, details); 920 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 921 922 return addr; 923 } 924 925 static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 926 struct vm_area_struct *vma, pgd_t *pgd, 927 unsigned long addr, unsigned long end, 928 long *zap_work, struct zap_details *details) 929 { 930 pud_t *pud; 931 unsigned long next; 932 933 pud = pud_offset(pgd, addr); 934 do { 935 next = pud_addr_end(addr, end); 936 if (pud_none_or_clear_bad(pud)) { 937 (*zap_work)--; 938 continue; 939 } 940 next = zap_pmd_range(tlb, vma, pud, addr, next, 941 zap_work, details); 942 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 943 944 return addr; 945 } 946 947 static unsigned long unmap_page_range(struct mmu_gather *tlb, 948 struct vm_area_struct *vma, 949 unsigned long addr, unsigned long end, 950 long *zap_work, struct zap_details *details) 951 { 952 pgd_t *pgd; 953 unsigned long next; 954 955 if (details && !details->check_mapping && !details->nonlinear_vma) 956 details = NULL; 957 958 BUG_ON(addr >= end); 959 mem_cgroup_uncharge_start(); 960 tlb_start_vma(tlb, vma); 961 pgd = pgd_offset(vma->vm_mm, addr); 962 do { 963 next = pgd_addr_end(addr, end); 964 if (pgd_none_or_clear_bad(pgd)) { 965 (*zap_work)--; 966 continue; 967 } 968 next = zap_pud_range(tlb, vma, pgd, addr, next, 969 zap_work, details); 970 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 971 tlb_end_vma(tlb, vma); 972 mem_cgroup_uncharge_end(); 973 974 return addr; 975 } 976 977 #ifdef CONFIG_PREEMPT 978 # define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 979 #else 980 /* No preempt: go for improved straight-line efficiency */ 981 # define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 982 #endif 983 984 /** 985 * unmap_vmas - unmap a range of memory covered by a list of vma's 986 * @tlbp: address of the caller's struct mmu_gather 987 * @vma: the starting vma 988 * @start_addr: virtual address at which to start unmapping 989 * @end_addr: virtual address at which to end unmapping 990 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 991 * @details: details of nonlinear truncation or shared cache invalidation 992 * 993 * Returns the end address of the unmapping (restart addr if interrupted). 994 * 995 * Unmap all pages in the vma list. 996 * 997 * We aim to not hold locks for too long (for scheduling latency reasons). 998 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 999 * return the ending mmu_gather to the caller. 1000 * 1001 * Only addresses between `start' and `end' will be unmapped. 1002 * 1003 * The VMA list must be sorted in ascending virtual address order. 1004 * 1005 * unmap_vmas() assumes that the caller will flush the whole unmapped address 1006 * range after unmap_vmas() returns. So the only responsibility here is to 1007 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 1008 * drops the lock and schedules. 1009 */ 1010 unsigned long unmap_vmas(struct mmu_gather **tlbp, 1011 struct vm_area_struct *vma, unsigned long start_addr, 1012 unsigned long end_addr, unsigned long *nr_accounted, 1013 struct zap_details *details) 1014 { 1015 long zap_work = ZAP_BLOCK_SIZE; 1016 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 1017 int tlb_start_valid = 0; 1018 unsigned long start = start_addr; 1019 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 1020 int fullmm = (*tlbp)->fullmm; 1021 struct mm_struct *mm = vma->vm_mm; 1022 1023 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 1024 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 1025 unsigned long end; 1026 1027 start = max(vma->vm_start, start_addr); 1028 if (start >= vma->vm_end) 1029 continue; 1030 end = min(vma->vm_end, end_addr); 1031 if (end <= vma->vm_start) 1032 continue; 1033 1034 if (vma->vm_flags & VM_ACCOUNT) 1035 *nr_accounted += (end - start) >> PAGE_SHIFT; 1036 1037 if (unlikely(is_pfn_mapping(vma))) 1038 untrack_pfn_vma(vma, 0, 0); 1039 1040 while (start != end) { 1041 if (!tlb_start_valid) { 1042 tlb_start = start; 1043 tlb_start_valid = 1; 1044 } 1045 1046 if (unlikely(is_vm_hugetlb_page(vma))) { 1047 /* 1048 * It is undesirable to test vma->vm_file as it 1049 * should be non-null for valid hugetlb area. 1050 * However, vm_file will be NULL in the error 1051 * cleanup path of do_mmap_pgoff. When 1052 * hugetlbfs ->mmap method fails, 1053 * do_mmap_pgoff() nullifies vma->vm_file 1054 * before calling this function to clean up. 1055 * Since no pte has actually been setup, it is 1056 * safe to do nothing in this case. 1057 */ 1058 if (vma->vm_file) { 1059 unmap_hugepage_range(vma, start, end, NULL); 1060 zap_work -= (end - start) / 1061 pages_per_huge_page(hstate_vma(vma)); 1062 } 1063 1064 start = end; 1065 } else 1066 start = unmap_page_range(*tlbp, vma, 1067 start, end, &zap_work, details); 1068 1069 if (zap_work > 0) { 1070 BUG_ON(start != end); 1071 break; 1072 } 1073 1074 tlb_finish_mmu(*tlbp, tlb_start, start); 1075 1076 if (need_resched() || 1077 (i_mmap_lock && spin_needbreak(i_mmap_lock))) { 1078 if (i_mmap_lock) { 1079 *tlbp = NULL; 1080 goto out; 1081 } 1082 cond_resched(); 1083 } 1084 1085 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 1086 tlb_start_valid = 0; 1087 zap_work = ZAP_BLOCK_SIZE; 1088 } 1089 } 1090 out: 1091 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1092 return start; /* which is now the end (or restart) address */ 1093 } 1094 1095 /** 1096 * zap_page_range - remove user pages in a given range 1097 * @vma: vm_area_struct holding the applicable pages 1098 * @address: starting address of pages to zap 1099 * @size: number of bytes to zap 1100 * @details: details of nonlinear truncation or shared cache invalidation 1101 */ 1102 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 1103 unsigned long size, struct zap_details *details) 1104 { 1105 struct mm_struct *mm = vma->vm_mm; 1106 struct mmu_gather *tlb; 1107 unsigned long end = address + size; 1108 unsigned long nr_accounted = 0; 1109 1110 lru_add_drain(); 1111 tlb = tlb_gather_mmu(mm, 0); 1112 update_hiwater_rss(mm); 1113 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 1114 if (tlb) 1115 tlb_finish_mmu(tlb, address, end); 1116 return end; 1117 } 1118 1119 /** 1120 * zap_vma_ptes - remove ptes mapping the vma 1121 * @vma: vm_area_struct holding ptes to be zapped 1122 * @address: starting address of pages to zap 1123 * @size: number of bytes to zap 1124 * 1125 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1126 * 1127 * The entire address range must be fully contained within the vma. 1128 * 1129 * Returns 0 if successful. 1130 */ 1131 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1132 unsigned long size) 1133 { 1134 if (address < vma->vm_start || address + size > vma->vm_end || 1135 !(vma->vm_flags & VM_PFNMAP)) 1136 return -1; 1137 zap_page_range(vma, address, size, NULL); 1138 return 0; 1139 } 1140 EXPORT_SYMBOL_GPL(zap_vma_ptes); 1141 1142 /* 1143 * Do a quick page-table lookup for a single page. 1144 */ 1145 struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1146 unsigned int flags) 1147 { 1148 pgd_t *pgd; 1149 pud_t *pud; 1150 pmd_t *pmd; 1151 pte_t *ptep, pte; 1152 spinlock_t *ptl; 1153 struct page *page; 1154 struct mm_struct *mm = vma->vm_mm; 1155 1156 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 1157 if (!IS_ERR(page)) { 1158 BUG_ON(flags & FOLL_GET); 1159 goto out; 1160 } 1161 1162 page = NULL; 1163 pgd = pgd_offset(mm, address); 1164 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 1165 goto no_page_table; 1166 1167 pud = pud_offset(pgd, address); 1168 if (pud_none(*pud)) 1169 goto no_page_table; 1170 if (pud_huge(*pud)) { 1171 BUG_ON(flags & FOLL_GET); 1172 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); 1173 goto out; 1174 } 1175 if (unlikely(pud_bad(*pud))) 1176 goto no_page_table; 1177 1178 pmd = pmd_offset(pud, address); 1179 if (pmd_none(*pmd)) 1180 goto no_page_table; 1181 if (pmd_huge(*pmd)) { 1182 BUG_ON(flags & FOLL_GET); 1183 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 1184 goto out; 1185 } 1186 if (unlikely(pmd_bad(*pmd))) 1187 goto no_page_table; 1188 1189 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 1190 1191 pte = *ptep; 1192 if (!pte_present(pte)) 1193 goto no_page; 1194 if ((flags & FOLL_WRITE) && !pte_write(pte)) 1195 goto unlock; 1196 1197 page = vm_normal_page(vma, address, pte); 1198 if (unlikely(!page)) { 1199 if ((flags & FOLL_DUMP) || 1200 !is_zero_pfn(pte_pfn(pte))) 1201 goto bad_page; 1202 page = pte_page(pte); 1203 } 1204 1205 if (flags & FOLL_GET) 1206 get_page(page); 1207 if (flags & FOLL_TOUCH) { 1208 if ((flags & FOLL_WRITE) && 1209 !pte_dirty(pte) && !PageDirty(page)) 1210 set_page_dirty(page); 1211 /* 1212 * pte_mkyoung() would be more correct here, but atomic care 1213 * is needed to avoid losing the dirty bit: it is easier to use 1214 * mark_page_accessed(). 1215 */ 1216 mark_page_accessed(page); 1217 } 1218 unlock: 1219 pte_unmap_unlock(ptep, ptl); 1220 out: 1221 return page; 1222 1223 bad_page: 1224 pte_unmap_unlock(ptep, ptl); 1225 return ERR_PTR(-EFAULT); 1226 1227 no_page: 1228 pte_unmap_unlock(ptep, ptl); 1229 if (!pte_none(pte)) 1230 return page; 1231 1232 no_page_table: 1233 /* 1234 * When core dumping an enormous anonymous area that nobody 1235 * has touched so far, we don't want to allocate unnecessary pages or 1236 * page tables. Return error instead of NULL to skip handle_mm_fault, 1237 * then get_dump_page() will return NULL to leave a hole in the dump. 1238 * But we can only make this optimization where a hole would surely 1239 * be zero-filled if handle_mm_fault() actually did handle it. 1240 */ 1241 if ((flags & FOLL_DUMP) && 1242 (!vma->vm_ops || !vma->vm_ops->fault)) 1243 return ERR_PTR(-EFAULT); 1244 return page; 1245 } 1246 1247 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1248 unsigned long start, int nr_pages, unsigned int gup_flags, 1249 struct page **pages, struct vm_area_struct **vmas) 1250 { 1251 int i; 1252 unsigned long vm_flags; 1253 1254 if (nr_pages <= 0) 1255 return 0; 1256 1257 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET)); 1258 1259 /* 1260 * Require read or write permissions. 1261 * If FOLL_FORCE is set, we only require the "MAY" flags. 1262 */ 1263 vm_flags = (gup_flags & FOLL_WRITE) ? 1264 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 1265 vm_flags &= (gup_flags & FOLL_FORCE) ? 1266 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 1267 i = 0; 1268 1269 do { 1270 struct vm_area_struct *vma; 1271 1272 vma = find_extend_vma(mm, start); 1273 if (!vma && in_gate_area(tsk, start)) { 1274 unsigned long pg = start & PAGE_MASK; 1275 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 1276 pgd_t *pgd; 1277 pud_t *pud; 1278 pmd_t *pmd; 1279 pte_t *pte; 1280 1281 /* user gate pages are read-only */ 1282 if (gup_flags & FOLL_WRITE) 1283 return i ? : -EFAULT; 1284 if (pg > TASK_SIZE) 1285 pgd = pgd_offset_k(pg); 1286 else 1287 pgd = pgd_offset_gate(mm, pg); 1288 BUG_ON(pgd_none(*pgd)); 1289 pud = pud_offset(pgd, pg); 1290 BUG_ON(pud_none(*pud)); 1291 pmd = pmd_offset(pud, pg); 1292 if (pmd_none(*pmd)) 1293 return i ? : -EFAULT; 1294 pte = pte_offset_map(pmd, pg); 1295 if (pte_none(*pte)) { 1296 pte_unmap(pte); 1297 return i ? : -EFAULT; 1298 } 1299 if (pages) { 1300 struct page *page = vm_normal_page(gate_vma, start, *pte); 1301 pages[i] = page; 1302 if (page) 1303 get_page(page); 1304 } 1305 pte_unmap(pte); 1306 if (vmas) 1307 vmas[i] = gate_vma; 1308 i++; 1309 start += PAGE_SIZE; 1310 nr_pages--; 1311 continue; 1312 } 1313 1314 if (!vma || 1315 (vma->vm_flags & (VM_IO | VM_PFNMAP)) || 1316 !(vm_flags & vma->vm_flags)) 1317 return i ? : -EFAULT; 1318 1319 if (is_vm_hugetlb_page(vma)) { 1320 i = follow_hugetlb_page(mm, vma, pages, vmas, 1321 &start, &nr_pages, i, gup_flags); 1322 continue; 1323 } 1324 1325 do { 1326 struct page *page; 1327 unsigned int foll_flags = gup_flags; 1328 1329 /* 1330 * If we have a pending SIGKILL, don't keep faulting 1331 * pages and potentially allocating memory. 1332 */ 1333 if (unlikely(fatal_signal_pending(current))) 1334 return i ? i : -ERESTARTSYS; 1335 1336 cond_resched(); 1337 while (!(page = follow_page(vma, start, foll_flags))) { 1338 int ret; 1339 1340 ret = handle_mm_fault(mm, vma, start, 1341 (foll_flags & FOLL_WRITE) ? 1342 FAULT_FLAG_WRITE : 0); 1343 1344 if (ret & VM_FAULT_ERROR) { 1345 if (ret & VM_FAULT_OOM) 1346 return i ? i : -ENOMEM; 1347 if (ret & 1348 (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS)) 1349 return i ? i : -EFAULT; 1350 BUG(); 1351 } 1352 if (ret & VM_FAULT_MAJOR) 1353 tsk->maj_flt++; 1354 else 1355 tsk->min_flt++; 1356 1357 /* 1358 * The VM_FAULT_WRITE bit tells us that 1359 * do_wp_page has broken COW when necessary, 1360 * even if maybe_mkwrite decided not to set 1361 * pte_write. We can thus safely do subsequent 1362 * page lookups as if they were reads. But only 1363 * do so when looping for pte_write is futile: 1364 * in some cases userspace may also be wanting 1365 * to write to the gotten user page, which a 1366 * read fault here might prevent (a readonly 1367 * page might get reCOWed by userspace write). 1368 */ 1369 if ((ret & VM_FAULT_WRITE) && 1370 !(vma->vm_flags & VM_WRITE)) 1371 foll_flags &= ~FOLL_WRITE; 1372 1373 cond_resched(); 1374 } 1375 if (IS_ERR(page)) 1376 return i ? i : PTR_ERR(page); 1377 if (pages) { 1378 pages[i] = page; 1379 1380 flush_anon_page(vma, page, start); 1381 flush_dcache_page(page); 1382 } 1383 if (vmas) 1384 vmas[i] = vma; 1385 i++; 1386 start += PAGE_SIZE; 1387 nr_pages--; 1388 } while (nr_pages && start < vma->vm_end); 1389 } while (nr_pages); 1390 return i; 1391 } 1392 1393 /** 1394 * get_user_pages() - pin user pages in memory 1395 * @tsk: task_struct of target task 1396 * @mm: mm_struct of target mm 1397 * @start: starting user address 1398 * @nr_pages: number of pages from start to pin 1399 * @write: whether pages will be written to by the caller 1400 * @force: whether to force write access even if user mapping is 1401 * readonly. This will result in the page being COWed even 1402 * in MAP_SHARED mappings. You do not want this. 1403 * @pages: array that receives pointers to the pages pinned. 1404 * Should be at least nr_pages long. Or NULL, if caller 1405 * only intends to ensure the pages are faulted in. 1406 * @vmas: array of pointers to vmas corresponding to each page. 1407 * Or NULL if the caller does not require them. 1408 * 1409 * Returns number of pages pinned. This may be fewer than the number 1410 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1411 * were pinned, returns -errno. Each page returned must be released 1412 * with a put_page() call when it is finished with. vmas will only 1413 * remain valid while mmap_sem is held. 1414 * 1415 * Must be called with mmap_sem held for read or write. 1416 * 1417 * get_user_pages walks a process's page tables and takes a reference to 1418 * each struct page that each user address corresponds to at a given 1419 * instant. That is, it takes the page that would be accessed if a user 1420 * thread accesses the given user virtual address at that instant. 1421 * 1422 * This does not guarantee that the page exists in the user mappings when 1423 * get_user_pages returns, and there may even be a completely different 1424 * page there in some cases (eg. if mmapped pagecache has been invalidated 1425 * and subsequently re faulted). However it does guarantee that the page 1426 * won't be freed completely. And mostly callers simply care that the page 1427 * contains data that was valid *at some point in time*. Typically, an IO 1428 * or similar operation cannot guarantee anything stronger anyway because 1429 * locks can't be held over the syscall boundary. 1430 * 1431 * If write=0, the page must not be written to. If the page is written to, 1432 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called 1433 * after the page is finished with, and before put_page is called. 1434 * 1435 * get_user_pages is typically used for fewer-copy IO operations, to get a 1436 * handle on the memory by some means other than accesses via the user virtual 1437 * addresses. The pages may be submitted for DMA to devices or accessed via 1438 * their kernel linear mapping (via the kmap APIs). Care should be taken to 1439 * use the correct cache flushing APIs. 1440 * 1441 * See also get_user_pages_fast, for performance critical applications. 1442 */ 1443 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1444 unsigned long start, int nr_pages, int write, int force, 1445 struct page **pages, struct vm_area_struct **vmas) 1446 { 1447 int flags = FOLL_TOUCH; 1448 1449 if (pages) 1450 flags |= FOLL_GET; 1451 if (write) 1452 flags |= FOLL_WRITE; 1453 if (force) 1454 flags |= FOLL_FORCE; 1455 1456 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas); 1457 } 1458 EXPORT_SYMBOL(get_user_pages); 1459 1460 /** 1461 * get_dump_page() - pin user page in memory while writing it to core dump 1462 * @addr: user address 1463 * 1464 * Returns struct page pointer of user page pinned for dump, 1465 * to be freed afterwards by page_cache_release() or put_page(). 1466 * 1467 * Returns NULL on any kind of failure - a hole must then be inserted into 1468 * the corefile, to preserve alignment with its headers; and also returns 1469 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found - 1470 * allowing a hole to be left in the corefile to save diskspace. 1471 * 1472 * Called without mmap_sem, but after all other threads have been killed. 1473 */ 1474 #ifdef CONFIG_ELF_CORE 1475 struct page *get_dump_page(unsigned long addr) 1476 { 1477 struct vm_area_struct *vma; 1478 struct page *page; 1479 1480 if (__get_user_pages(current, current->mm, addr, 1, 1481 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1) 1482 return NULL; 1483 flush_cache_page(vma, addr, page_to_pfn(page)); 1484 return page; 1485 } 1486 #endif /* CONFIG_ELF_CORE */ 1487 1488 pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr, 1489 spinlock_t **ptl) 1490 { 1491 pgd_t * pgd = pgd_offset(mm, addr); 1492 pud_t * pud = pud_alloc(mm, pgd, addr); 1493 if (pud) { 1494 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1495 if (pmd) 1496 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1497 } 1498 return NULL; 1499 } 1500 1501 /* 1502 * This is the old fallback for page remapping. 1503 * 1504 * For historical reasons, it only allows reserved pages. Only 1505 * old drivers should use this, and they needed to mark their 1506 * pages reserved for the old functions anyway. 1507 */ 1508 static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1509 struct page *page, pgprot_t prot) 1510 { 1511 struct mm_struct *mm = vma->vm_mm; 1512 int retval; 1513 pte_t *pte; 1514 spinlock_t *ptl; 1515 1516 retval = -EINVAL; 1517 if (PageAnon(page)) 1518 goto out; 1519 retval = -ENOMEM; 1520 flush_dcache_page(page); 1521 pte = get_locked_pte(mm, addr, &ptl); 1522 if (!pte) 1523 goto out; 1524 retval = -EBUSY; 1525 if (!pte_none(*pte)) 1526 goto out_unlock; 1527 1528 /* Ok, finally just insert the thing.. */ 1529 get_page(page); 1530 inc_mm_counter(mm, file_rss); 1531 page_add_file_rmap(page); 1532 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1533 1534 retval = 0; 1535 pte_unmap_unlock(pte, ptl); 1536 return retval; 1537 out_unlock: 1538 pte_unmap_unlock(pte, ptl); 1539 out: 1540 return retval; 1541 } 1542 1543 /** 1544 * vm_insert_page - insert single page into user vma 1545 * @vma: user vma to map to 1546 * @addr: target user address of this page 1547 * @page: source kernel page 1548 * 1549 * This allows drivers to insert individual pages they've allocated 1550 * into a user vma. 1551 * 1552 * The page has to be a nice clean _individual_ kernel allocation. 1553 * If you allocate a compound page, you need to have marked it as 1554 * such (__GFP_COMP), or manually just split the page up yourself 1555 * (see split_page()). 1556 * 1557 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1558 * took an arbitrary page protection parameter. This doesn't allow 1559 * that. Your vma protection will have to be set up correctly, which 1560 * means that if you want a shared writable mapping, you'd better 1561 * ask for a shared writable mapping! 1562 * 1563 * The page does not need to be reserved. 1564 */ 1565 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1566 struct page *page) 1567 { 1568 if (addr < vma->vm_start || addr >= vma->vm_end) 1569 return -EFAULT; 1570 if (!page_count(page)) 1571 return -EINVAL; 1572 vma->vm_flags |= VM_INSERTPAGE; 1573 return insert_page(vma, addr, page, vma->vm_page_prot); 1574 } 1575 EXPORT_SYMBOL(vm_insert_page); 1576 1577 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1578 unsigned long pfn, pgprot_t prot) 1579 { 1580 struct mm_struct *mm = vma->vm_mm; 1581 int retval; 1582 pte_t *pte, entry; 1583 spinlock_t *ptl; 1584 1585 retval = -ENOMEM; 1586 pte = get_locked_pte(mm, addr, &ptl); 1587 if (!pte) 1588 goto out; 1589 retval = -EBUSY; 1590 if (!pte_none(*pte)) 1591 goto out_unlock; 1592 1593 /* Ok, finally just insert the thing.. */ 1594 entry = pte_mkspecial(pfn_pte(pfn, prot)); 1595 set_pte_at(mm, addr, pte, entry); 1596 update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */ 1597 1598 retval = 0; 1599 out_unlock: 1600 pte_unmap_unlock(pte, ptl); 1601 out: 1602 return retval; 1603 } 1604 1605 /** 1606 * vm_insert_pfn - insert single pfn into user vma 1607 * @vma: user vma to map to 1608 * @addr: target user address of this page 1609 * @pfn: source kernel pfn 1610 * 1611 * Similar to vm_inert_page, this allows drivers to insert individual pages 1612 * they've allocated into a user vma. Same comments apply. 1613 * 1614 * This function should only be called from a vm_ops->fault handler, and 1615 * in that case the handler should return NULL. 1616 * 1617 * vma cannot be a COW mapping. 1618 * 1619 * As this is called only for pages that do not currently exist, we 1620 * do not need to flush old virtual caches or the TLB. 1621 */ 1622 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1623 unsigned long pfn) 1624 { 1625 int ret; 1626 pgprot_t pgprot = vma->vm_page_prot; 1627 /* 1628 * Technically, architectures with pte_special can avoid all these 1629 * restrictions (same for remap_pfn_range). However we would like 1630 * consistency in testing and feature parity among all, so we should 1631 * try to keep these invariants in place for everybody. 1632 */ 1633 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 1634 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1635 (VM_PFNMAP|VM_MIXEDMAP)); 1636 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1637 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 1638 1639 if (addr < vma->vm_start || addr >= vma->vm_end) 1640 return -EFAULT; 1641 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE)) 1642 return -EINVAL; 1643 1644 ret = insert_pfn(vma, addr, pfn, pgprot); 1645 1646 if (ret) 1647 untrack_pfn_vma(vma, pfn, PAGE_SIZE); 1648 1649 return ret; 1650 } 1651 EXPORT_SYMBOL(vm_insert_pfn); 1652 1653 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1654 unsigned long pfn) 1655 { 1656 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 1657 1658 if (addr < vma->vm_start || addr >= vma->vm_end) 1659 return -EFAULT; 1660 1661 /* 1662 * If we don't have pte special, then we have to use the pfn_valid() 1663 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 1664 * refcount the page if pfn_valid is true (hence insert_page rather 1665 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP 1666 * without pte special, it would there be refcounted as a normal page. 1667 */ 1668 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 1669 struct page *page; 1670 1671 page = pfn_to_page(pfn); 1672 return insert_page(vma, addr, page, vma->vm_page_prot); 1673 } 1674 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 1675 } 1676 EXPORT_SYMBOL(vm_insert_mixed); 1677 1678 /* 1679 * maps a range of physical memory into the requested pages. the old 1680 * mappings are removed. any references to nonexistent pages results 1681 * in null mappings (currently treated as "copy-on-access") 1682 */ 1683 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1684 unsigned long addr, unsigned long end, 1685 unsigned long pfn, pgprot_t prot) 1686 { 1687 pte_t *pte; 1688 spinlock_t *ptl; 1689 1690 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1691 if (!pte) 1692 return -ENOMEM; 1693 arch_enter_lazy_mmu_mode(); 1694 do { 1695 BUG_ON(!pte_none(*pte)); 1696 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 1697 pfn++; 1698 } while (pte++, addr += PAGE_SIZE, addr != end); 1699 arch_leave_lazy_mmu_mode(); 1700 pte_unmap_unlock(pte - 1, ptl); 1701 return 0; 1702 } 1703 1704 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1705 unsigned long addr, unsigned long end, 1706 unsigned long pfn, pgprot_t prot) 1707 { 1708 pmd_t *pmd; 1709 unsigned long next; 1710 1711 pfn -= addr >> PAGE_SHIFT; 1712 pmd = pmd_alloc(mm, pud, addr); 1713 if (!pmd) 1714 return -ENOMEM; 1715 do { 1716 next = pmd_addr_end(addr, end); 1717 if (remap_pte_range(mm, pmd, addr, next, 1718 pfn + (addr >> PAGE_SHIFT), prot)) 1719 return -ENOMEM; 1720 } while (pmd++, addr = next, addr != end); 1721 return 0; 1722 } 1723 1724 static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1725 unsigned long addr, unsigned long end, 1726 unsigned long pfn, pgprot_t prot) 1727 { 1728 pud_t *pud; 1729 unsigned long next; 1730 1731 pfn -= addr >> PAGE_SHIFT; 1732 pud = pud_alloc(mm, pgd, addr); 1733 if (!pud) 1734 return -ENOMEM; 1735 do { 1736 next = pud_addr_end(addr, end); 1737 if (remap_pmd_range(mm, pud, addr, next, 1738 pfn + (addr >> PAGE_SHIFT), prot)) 1739 return -ENOMEM; 1740 } while (pud++, addr = next, addr != end); 1741 return 0; 1742 } 1743 1744 /** 1745 * remap_pfn_range - remap kernel memory to userspace 1746 * @vma: user vma to map to 1747 * @addr: target user address to start at 1748 * @pfn: physical address of kernel memory 1749 * @size: size of map area 1750 * @prot: page protection flags for this mapping 1751 * 1752 * Note: this is only safe if the mm semaphore is held when called. 1753 */ 1754 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1755 unsigned long pfn, unsigned long size, pgprot_t prot) 1756 { 1757 pgd_t *pgd; 1758 unsigned long next; 1759 unsigned long end = addr + PAGE_ALIGN(size); 1760 struct mm_struct *mm = vma->vm_mm; 1761 int err; 1762 1763 /* 1764 * Physically remapped pages are special. Tell the 1765 * rest of the world about it: 1766 * VM_IO tells people not to look at these pages 1767 * (accesses can have side effects). 1768 * VM_RESERVED is specified all over the place, because 1769 * in 2.4 it kept swapout's vma scan off this vma; but 1770 * in 2.6 the LRU scan won't even find its pages, so this 1771 * flag means no more than count its pages in reserved_vm, 1772 * and omit it from core dump, even when VM_IO turned off. 1773 * VM_PFNMAP tells the core MM that the base pages are just 1774 * raw PFN mappings, and do not have a "struct page" associated 1775 * with them. 1776 * 1777 * There's a horrible special case to handle copy-on-write 1778 * behaviour that some programs depend on. We mark the "original" 1779 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1780 */ 1781 if (addr == vma->vm_start && end == vma->vm_end) { 1782 vma->vm_pgoff = pfn; 1783 vma->vm_flags |= VM_PFN_AT_MMAP; 1784 } else if (is_cow_mapping(vma->vm_flags)) 1785 return -EINVAL; 1786 1787 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 1788 1789 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size)); 1790 if (err) { 1791 /* 1792 * To indicate that track_pfn related cleanup is not 1793 * needed from higher level routine calling unmap_vmas 1794 */ 1795 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP); 1796 vma->vm_flags &= ~VM_PFN_AT_MMAP; 1797 return -EINVAL; 1798 } 1799 1800 BUG_ON(addr >= end); 1801 pfn -= addr >> PAGE_SHIFT; 1802 pgd = pgd_offset(mm, addr); 1803 flush_cache_range(vma, addr, end); 1804 do { 1805 next = pgd_addr_end(addr, end); 1806 err = remap_pud_range(mm, pgd, addr, next, 1807 pfn + (addr >> PAGE_SHIFT), prot); 1808 if (err) 1809 break; 1810 } while (pgd++, addr = next, addr != end); 1811 1812 if (err) 1813 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size)); 1814 1815 return err; 1816 } 1817 EXPORT_SYMBOL(remap_pfn_range); 1818 1819 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 1820 unsigned long addr, unsigned long end, 1821 pte_fn_t fn, void *data) 1822 { 1823 pte_t *pte; 1824 int err; 1825 pgtable_t token; 1826 spinlock_t *uninitialized_var(ptl); 1827 1828 pte = (mm == &init_mm) ? 1829 pte_alloc_kernel(pmd, addr) : 1830 pte_alloc_map_lock(mm, pmd, addr, &ptl); 1831 if (!pte) 1832 return -ENOMEM; 1833 1834 BUG_ON(pmd_huge(*pmd)); 1835 1836 arch_enter_lazy_mmu_mode(); 1837 1838 token = pmd_pgtable(*pmd); 1839 1840 do { 1841 err = fn(pte++, token, addr, data); 1842 if (err) 1843 break; 1844 } while (addr += PAGE_SIZE, addr != end); 1845 1846 arch_leave_lazy_mmu_mode(); 1847 1848 if (mm != &init_mm) 1849 pte_unmap_unlock(pte-1, ptl); 1850 return err; 1851 } 1852 1853 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 1854 unsigned long addr, unsigned long end, 1855 pte_fn_t fn, void *data) 1856 { 1857 pmd_t *pmd; 1858 unsigned long next; 1859 int err; 1860 1861 BUG_ON(pud_huge(*pud)); 1862 1863 pmd = pmd_alloc(mm, pud, addr); 1864 if (!pmd) 1865 return -ENOMEM; 1866 do { 1867 next = pmd_addr_end(addr, end); 1868 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 1869 if (err) 1870 break; 1871 } while (pmd++, addr = next, addr != end); 1872 return err; 1873 } 1874 1875 static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 1876 unsigned long addr, unsigned long end, 1877 pte_fn_t fn, void *data) 1878 { 1879 pud_t *pud; 1880 unsigned long next; 1881 int err; 1882 1883 pud = pud_alloc(mm, pgd, addr); 1884 if (!pud) 1885 return -ENOMEM; 1886 do { 1887 next = pud_addr_end(addr, end); 1888 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 1889 if (err) 1890 break; 1891 } while (pud++, addr = next, addr != end); 1892 return err; 1893 } 1894 1895 /* 1896 * Scan a region of virtual memory, filling in page tables as necessary 1897 * and calling a provided function on each leaf page table. 1898 */ 1899 int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 1900 unsigned long size, pte_fn_t fn, void *data) 1901 { 1902 pgd_t *pgd; 1903 unsigned long next; 1904 unsigned long start = addr, end = addr + size; 1905 int err; 1906 1907 BUG_ON(addr >= end); 1908 mmu_notifier_invalidate_range_start(mm, start, end); 1909 pgd = pgd_offset(mm, addr); 1910 do { 1911 next = pgd_addr_end(addr, end); 1912 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 1913 if (err) 1914 break; 1915 } while (pgd++, addr = next, addr != end); 1916 mmu_notifier_invalidate_range_end(mm, start, end); 1917 return err; 1918 } 1919 EXPORT_SYMBOL_GPL(apply_to_page_range); 1920 1921 /* 1922 * handle_pte_fault chooses page fault handler according to an entry 1923 * which was read non-atomically. Before making any commitment, on 1924 * those architectures or configurations (e.g. i386 with PAE) which 1925 * might give a mix of unmatched parts, do_swap_page and do_file_page 1926 * must check under lock before unmapping the pte and proceeding 1927 * (but do_wp_page is only called after already making such a check; 1928 * and do_anonymous_page and do_no_page can safely check later on). 1929 */ 1930 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1931 pte_t *page_table, pte_t orig_pte) 1932 { 1933 int same = 1; 1934 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1935 if (sizeof(pte_t) > sizeof(unsigned long)) { 1936 spinlock_t *ptl = pte_lockptr(mm, pmd); 1937 spin_lock(ptl); 1938 same = pte_same(*page_table, orig_pte); 1939 spin_unlock(ptl); 1940 } 1941 #endif 1942 pte_unmap(page_table); 1943 return same; 1944 } 1945 1946 /* 1947 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1948 * servicing faults for write access. In the normal case, do always want 1949 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1950 * that do not have writing enabled, when used by access_process_vm. 1951 */ 1952 static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1953 { 1954 if (likely(vma->vm_flags & VM_WRITE)) 1955 pte = pte_mkwrite(pte); 1956 return pte; 1957 } 1958 1959 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1960 { 1961 /* 1962 * If the source page was a PFN mapping, we don't have 1963 * a "struct page" for it. We do a best-effort copy by 1964 * just copying from the original user address. If that 1965 * fails, we just zero-fill it. Live with it. 1966 */ 1967 if (unlikely(!src)) { 1968 void *kaddr = kmap_atomic(dst, KM_USER0); 1969 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1970 1971 /* 1972 * This really shouldn't fail, because the page is there 1973 * in the page tables. But it might just be unreadable, 1974 * in which case we just give up and fill the result with 1975 * zeroes. 1976 */ 1977 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1978 memset(kaddr, 0, PAGE_SIZE); 1979 kunmap_atomic(kaddr, KM_USER0); 1980 flush_dcache_page(dst); 1981 } else 1982 copy_user_highpage(dst, src, va, vma); 1983 } 1984 1985 /* 1986 * This routine handles present pages, when users try to write 1987 * to a shared page. It is done by copying the page to a new address 1988 * and decrementing the shared-page counter for the old page. 1989 * 1990 * Note that this routine assumes that the protection checks have been 1991 * done by the caller (the low-level page fault routine in most cases). 1992 * Thus we can safely just mark it writable once we've done any necessary 1993 * COW. 1994 * 1995 * We also mark the page dirty at this point even though the page will 1996 * change only once the write actually happens. This avoids a few races, 1997 * and potentially makes it more efficient. 1998 * 1999 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2000 * but allow concurrent faults), with pte both mapped and locked. 2001 * We return with mmap_sem still held, but pte unmapped and unlocked. 2002 */ 2003 static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 2004 unsigned long address, pte_t *page_table, pmd_t *pmd, 2005 spinlock_t *ptl, pte_t orig_pte) 2006 { 2007 struct page *old_page, *new_page; 2008 pte_t entry; 2009 int reuse = 0, ret = 0; 2010 int page_mkwrite = 0; 2011 struct page *dirty_page = NULL; 2012 2013 old_page = vm_normal_page(vma, address, orig_pte); 2014 if (!old_page) { 2015 /* 2016 * VM_MIXEDMAP !pfn_valid() case 2017 * 2018 * We should not cow pages in a shared writeable mapping. 2019 * Just mark the pages writable as we can't do any dirty 2020 * accounting on raw pfn maps. 2021 */ 2022 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2023 (VM_WRITE|VM_SHARED)) 2024 goto reuse; 2025 goto gotten; 2026 } 2027 2028 /* 2029 * Take out anonymous pages first, anonymous shared vmas are 2030 * not dirty accountable. 2031 */ 2032 if (PageAnon(old_page) && !PageKsm(old_page)) { 2033 if (!trylock_page(old_page)) { 2034 page_cache_get(old_page); 2035 pte_unmap_unlock(page_table, ptl); 2036 lock_page(old_page); 2037 page_table = pte_offset_map_lock(mm, pmd, address, 2038 &ptl); 2039 if (!pte_same(*page_table, orig_pte)) { 2040 unlock_page(old_page); 2041 page_cache_release(old_page); 2042 goto unlock; 2043 } 2044 page_cache_release(old_page); 2045 } 2046 reuse = reuse_swap_page(old_page); 2047 unlock_page(old_page); 2048 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 2049 (VM_WRITE|VM_SHARED))) { 2050 /* 2051 * Only catch write-faults on shared writable pages, 2052 * read-only shared pages can get COWed by 2053 * get_user_pages(.write=1, .force=1). 2054 */ 2055 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2056 struct vm_fault vmf; 2057 int tmp; 2058 2059 vmf.virtual_address = (void __user *)(address & 2060 PAGE_MASK); 2061 vmf.pgoff = old_page->index; 2062 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2063 vmf.page = old_page; 2064 2065 /* 2066 * Notify the address space that the page is about to 2067 * become writable so that it can prohibit this or wait 2068 * for the page to get into an appropriate state. 2069 * 2070 * We do this without the lock held, so that it can 2071 * sleep if it needs to. 2072 */ 2073 page_cache_get(old_page); 2074 pte_unmap_unlock(page_table, ptl); 2075 2076 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 2077 if (unlikely(tmp & 2078 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2079 ret = tmp; 2080 goto unwritable_page; 2081 } 2082 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 2083 lock_page(old_page); 2084 if (!old_page->mapping) { 2085 ret = 0; /* retry the fault */ 2086 unlock_page(old_page); 2087 goto unwritable_page; 2088 } 2089 } else 2090 VM_BUG_ON(!PageLocked(old_page)); 2091 2092 /* 2093 * Since we dropped the lock we need to revalidate 2094 * the PTE as someone else may have changed it. If 2095 * they did, we just return, as we can count on the 2096 * MMU to tell us if they didn't also make it writable. 2097 */ 2098 page_table = pte_offset_map_lock(mm, pmd, address, 2099 &ptl); 2100 if (!pte_same(*page_table, orig_pte)) { 2101 unlock_page(old_page); 2102 page_cache_release(old_page); 2103 goto unlock; 2104 } 2105 2106 page_mkwrite = 1; 2107 } 2108 dirty_page = old_page; 2109 get_page(dirty_page); 2110 reuse = 1; 2111 } 2112 2113 if (reuse) { 2114 reuse: 2115 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2116 entry = pte_mkyoung(orig_pte); 2117 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2118 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2119 update_mmu_cache(vma, address, entry); 2120 ret |= VM_FAULT_WRITE; 2121 goto unlock; 2122 } 2123 2124 /* 2125 * Ok, we need to copy. Oh, well.. 2126 */ 2127 page_cache_get(old_page); 2128 gotten: 2129 pte_unmap_unlock(page_table, ptl); 2130 2131 if (unlikely(anon_vma_prepare(vma))) 2132 goto oom; 2133 2134 if (is_zero_pfn(pte_pfn(orig_pte))) { 2135 new_page = alloc_zeroed_user_highpage_movable(vma, address); 2136 if (!new_page) 2137 goto oom; 2138 } else { 2139 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2140 if (!new_page) 2141 goto oom; 2142 cow_user_page(new_page, old_page, address, vma); 2143 } 2144 __SetPageUptodate(new_page); 2145 2146 /* 2147 * Don't let another task, with possibly unlocked vma, 2148 * keep the mlocked page. 2149 */ 2150 if ((vma->vm_flags & VM_LOCKED) && old_page) { 2151 lock_page(old_page); /* for LRU manipulation */ 2152 clear_page_mlock(old_page); 2153 unlock_page(old_page); 2154 } 2155 2156 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) 2157 goto oom_free_new; 2158 2159 /* 2160 * Re-check the pte - we dropped the lock 2161 */ 2162 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2163 if (likely(pte_same(*page_table, orig_pte))) { 2164 if (old_page) { 2165 if (!PageAnon(old_page)) { 2166 dec_mm_counter(mm, file_rss); 2167 inc_mm_counter(mm, anon_rss); 2168 } 2169 } else 2170 inc_mm_counter(mm, anon_rss); 2171 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2172 entry = mk_pte(new_page, vma->vm_page_prot); 2173 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2174 /* 2175 * Clear the pte entry and flush it first, before updating the 2176 * pte with the new entry. This will avoid a race condition 2177 * seen in the presence of one thread doing SMC and another 2178 * thread doing COW. 2179 */ 2180 ptep_clear_flush(vma, address, page_table); 2181 page_add_new_anon_rmap(new_page, vma, address); 2182 /* 2183 * We call the notify macro here because, when using secondary 2184 * mmu page tables (such as kvm shadow page tables), we want the 2185 * new page to be mapped directly into the secondary page table. 2186 */ 2187 set_pte_at_notify(mm, address, page_table, entry); 2188 update_mmu_cache(vma, address, entry); 2189 if (old_page) { 2190 /* 2191 * Only after switching the pte to the new page may 2192 * we remove the mapcount here. Otherwise another 2193 * process may come and find the rmap count decremented 2194 * before the pte is switched to the new page, and 2195 * "reuse" the old page writing into it while our pte 2196 * here still points into it and can be read by other 2197 * threads. 2198 * 2199 * The critical issue is to order this 2200 * page_remove_rmap with the ptp_clear_flush above. 2201 * Those stores are ordered by (if nothing else,) 2202 * the barrier present in the atomic_add_negative 2203 * in page_remove_rmap. 2204 * 2205 * Then the TLB flush in ptep_clear_flush ensures that 2206 * no process can access the old page before the 2207 * decremented mapcount is visible. And the old page 2208 * cannot be reused until after the decremented 2209 * mapcount is visible. So transitively, TLBs to 2210 * old page will be flushed before it can be reused. 2211 */ 2212 page_remove_rmap(old_page); 2213 } 2214 2215 /* Free the old page.. */ 2216 new_page = old_page; 2217 ret |= VM_FAULT_WRITE; 2218 } else 2219 mem_cgroup_uncharge_page(new_page); 2220 2221 if (new_page) 2222 page_cache_release(new_page); 2223 if (old_page) 2224 page_cache_release(old_page); 2225 unlock: 2226 pte_unmap_unlock(page_table, ptl); 2227 if (dirty_page) { 2228 /* 2229 * Yes, Virginia, this is actually required to prevent a race 2230 * with clear_page_dirty_for_io() from clearing the page dirty 2231 * bit after it clear all dirty ptes, but before a racing 2232 * do_wp_page installs a dirty pte. 2233 * 2234 * do_no_page is protected similarly. 2235 */ 2236 if (!page_mkwrite) { 2237 wait_on_page_locked(dirty_page); 2238 set_page_dirty_balance(dirty_page, page_mkwrite); 2239 } 2240 put_page(dirty_page); 2241 if (page_mkwrite) { 2242 struct address_space *mapping = dirty_page->mapping; 2243 2244 set_page_dirty(dirty_page); 2245 unlock_page(dirty_page); 2246 page_cache_release(dirty_page); 2247 if (mapping) { 2248 /* 2249 * Some device drivers do not set page.mapping 2250 * but still dirty their pages 2251 */ 2252 balance_dirty_pages_ratelimited(mapping); 2253 } 2254 } 2255 2256 /* file_update_time outside page_lock */ 2257 if (vma->vm_file) 2258 file_update_time(vma->vm_file); 2259 } 2260 return ret; 2261 oom_free_new: 2262 page_cache_release(new_page); 2263 oom: 2264 if (old_page) { 2265 if (page_mkwrite) { 2266 unlock_page(old_page); 2267 page_cache_release(old_page); 2268 } 2269 page_cache_release(old_page); 2270 } 2271 return VM_FAULT_OOM; 2272 2273 unwritable_page: 2274 page_cache_release(old_page); 2275 return ret; 2276 } 2277 2278 /* 2279 * Helper functions for unmap_mapping_range(). 2280 * 2281 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 2282 * 2283 * We have to restart searching the prio_tree whenever we drop the lock, 2284 * since the iterator is only valid while the lock is held, and anyway 2285 * a later vma might be split and reinserted earlier while lock dropped. 2286 * 2287 * The list of nonlinear vmas could be handled more efficiently, using 2288 * a placeholder, but handle it in the same way until a need is shown. 2289 * It is important to search the prio_tree before nonlinear list: a vma 2290 * may become nonlinear and be shifted from prio_tree to nonlinear list 2291 * while the lock is dropped; but never shifted from list to prio_tree. 2292 * 2293 * In order to make forward progress despite restarting the search, 2294 * vm_truncate_count is used to mark a vma as now dealt with, so we can 2295 * quickly skip it next time around. Since the prio_tree search only 2296 * shows us those vmas affected by unmapping the range in question, we 2297 * can't efficiently keep all vmas in step with mapping->truncate_count: 2298 * so instead reset them all whenever it wraps back to 0 (then go to 1). 2299 * mapping->truncate_count and vma->vm_truncate_count are protected by 2300 * i_mmap_lock. 2301 * 2302 * In order to make forward progress despite repeatedly restarting some 2303 * large vma, note the restart_addr from unmap_vmas when it breaks out: 2304 * and restart from that address when we reach that vma again. It might 2305 * have been split or merged, shrunk or extended, but never shifted: so 2306 * restart_addr remains valid so long as it remains in the vma's range. 2307 * unmap_mapping_range forces truncate_count to leap over page-aligned 2308 * values so we can save vma's restart_addr in its truncate_count field. 2309 */ 2310 #define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 2311 2312 static void reset_vma_truncate_counts(struct address_space *mapping) 2313 { 2314 struct vm_area_struct *vma; 2315 struct prio_tree_iter iter; 2316 2317 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 2318 vma->vm_truncate_count = 0; 2319 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 2320 vma->vm_truncate_count = 0; 2321 } 2322 2323 static int unmap_mapping_range_vma(struct vm_area_struct *vma, 2324 unsigned long start_addr, unsigned long end_addr, 2325 struct zap_details *details) 2326 { 2327 unsigned long restart_addr; 2328 int need_break; 2329 2330 /* 2331 * files that support invalidating or truncating portions of the 2332 * file from under mmaped areas must have their ->fault function 2333 * return a locked page (and set VM_FAULT_LOCKED in the return). 2334 * This provides synchronisation against concurrent unmapping here. 2335 */ 2336 2337 again: 2338 restart_addr = vma->vm_truncate_count; 2339 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 2340 start_addr = restart_addr; 2341 if (start_addr >= end_addr) { 2342 /* Top of vma has been split off since last time */ 2343 vma->vm_truncate_count = details->truncate_count; 2344 return 0; 2345 } 2346 } 2347 2348 restart_addr = zap_page_range(vma, start_addr, 2349 end_addr - start_addr, details); 2350 need_break = need_resched() || spin_needbreak(details->i_mmap_lock); 2351 2352 if (restart_addr >= end_addr) { 2353 /* We have now completed this vma: mark it so */ 2354 vma->vm_truncate_count = details->truncate_count; 2355 if (!need_break) 2356 return 0; 2357 } else { 2358 /* Note restart_addr in vma's truncate_count field */ 2359 vma->vm_truncate_count = restart_addr; 2360 if (!need_break) 2361 goto again; 2362 } 2363 2364 spin_unlock(details->i_mmap_lock); 2365 cond_resched(); 2366 spin_lock(details->i_mmap_lock); 2367 return -EINTR; 2368 } 2369 2370 static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 2371 struct zap_details *details) 2372 { 2373 struct vm_area_struct *vma; 2374 struct prio_tree_iter iter; 2375 pgoff_t vba, vea, zba, zea; 2376 2377 restart: 2378 vma_prio_tree_foreach(vma, &iter, root, 2379 details->first_index, details->last_index) { 2380 /* Skip quickly over those we have already dealt with */ 2381 if (vma->vm_truncate_count == details->truncate_count) 2382 continue; 2383 2384 vba = vma->vm_pgoff; 2385 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 2386 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2387 zba = details->first_index; 2388 if (zba < vba) 2389 zba = vba; 2390 zea = details->last_index; 2391 if (zea > vea) 2392 zea = vea; 2393 2394 if (unmap_mapping_range_vma(vma, 2395 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2396 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2397 details) < 0) 2398 goto restart; 2399 } 2400 } 2401 2402 static inline void unmap_mapping_range_list(struct list_head *head, 2403 struct zap_details *details) 2404 { 2405 struct vm_area_struct *vma; 2406 2407 /* 2408 * In nonlinear VMAs there is no correspondence between virtual address 2409 * offset and file offset. So we must perform an exhaustive search 2410 * across *all* the pages in each nonlinear VMA, not just the pages 2411 * whose virtual address lies outside the file truncation point. 2412 */ 2413 restart: 2414 list_for_each_entry(vma, head, shared.vm_set.list) { 2415 /* Skip quickly over those we have already dealt with */ 2416 if (vma->vm_truncate_count == details->truncate_count) 2417 continue; 2418 details->nonlinear_vma = vma; 2419 if (unmap_mapping_range_vma(vma, vma->vm_start, 2420 vma->vm_end, details) < 0) 2421 goto restart; 2422 } 2423 } 2424 2425 /** 2426 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2427 * @mapping: the address space containing mmaps to be unmapped. 2428 * @holebegin: byte in first page to unmap, relative to the start of 2429 * the underlying file. This will be rounded down to a PAGE_SIZE 2430 * boundary. Note that this is different from truncate_pagecache(), which 2431 * must keep the partial page. In contrast, we must get rid of 2432 * partial pages. 2433 * @holelen: size of prospective hole in bytes. This will be rounded 2434 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2435 * end of the file. 2436 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2437 * but 0 when invalidating pagecache, don't throw away private data. 2438 */ 2439 void unmap_mapping_range(struct address_space *mapping, 2440 loff_t const holebegin, loff_t const holelen, int even_cows) 2441 { 2442 struct zap_details details; 2443 pgoff_t hba = holebegin >> PAGE_SHIFT; 2444 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2445 2446 /* Check for overflow. */ 2447 if (sizeof(holelen) > sizeof(hlen)) { 2448 long long holeend = 2449 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2450 if (holeend & ~(long long)ULONG_MAX) 2451 hlen = ULONG_MAX - hba + 1; 2452 } 2453 2454 details.check_mapping = even_cows? NULL: mapping; 2455 details.nonlinear_vma = NULL; 2456 details.first_index = hba; 2457 details.last_index = hba + hlen - 1; 2458 if (details.last_index < details.first_index) 2459 details.last_index = ULONG_MAX; 2460 details.i_mmap_lock = &mapping->i_mmap_lock; 2461 2462 spin_lock(&mapping->i_mmap_lock); 2463 2464 /* Protect against endless unmapping loops */ 2465 mapping->truncate_count++; 2466 if (unlikely(is_restart_addr(mapping->truncate_count))) { 2467 if (mapping->truncate_count == 0) 2468 reset_vma_truncate_counts(mapping); 2469 mapping->truncate_count++; 2470 } 2471 details.truncate_count = mapping->truncate_count; 2472 2473 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 2474 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2475 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 2476 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 2477 spin_unlock(&mapping->i_mmap_lock); 2478 } 2479 EXPORT_SYMBOL(unmap_mapping_range); 2480 2481 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 2482 { 2483 struct address_space *mapping = inode->i_mapping; 2484 2485 /* 2486 * If the underlying filesystem is not going to provide 2487 * a way to truncate a range of blocks (punch a hole) - 2488 * we should return failure right now. 2489 */ 2490 if (!inode->i_op->truncate_range) 2491 return -ENOSYS; 2492 2493 mutex_lock(&inode->i_mutex); 2494 down_write(&inode->i_alloc_sem); 2495 unmap_mapping_range(mapping, offset, (end - offset), 1); 2496 truncate_inode_pages_range(mapping, offset, end); 2497 unmap_mapping_range(mapping, offset, (end - offset), 1); 2498 inode->i_op->truncate_range(inode, offset, end); 2499 up_write(&inode->i_alloc_sem); 2500 mutex_unlock(&inode->i_mutex); 2501 2502 return 0; 2503 } 2504 2505 /* 2506 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2507 * but allow concurrent faults), and pte mapped but not yet locked. 2508 * We return with mmap_sem still held, but pte unmapped and unlocked. 2509 */ 2510 static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2511 unsigned long address, pte_t *page_table, pmd_t *pmd, 2512 unsigned int flags, pte_t orig_pte) 2513 { 2514 spinlock_t *ptl; 2515 struct page *page; 2516 swp_entry_t entry; 2517 pte_t pte; 2518 struct mem_cgroup *ptr = NULL; 2519 int ret = 0; 2520 2521 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2522 goto out; 2523 2524 entry = pte_to_swp_entry(orig_pte); 2525 if (unlikely(non_swap_entry(entry))) { 2526 if (is_migration_entry(entry)) { 2527 migration_entry_wait(mm, pmd, address); 2528 } else if (is_hwpoison_entry(entry)) { 2529 ret = VM_FAULT_HWPOISON; 2530 } else { 2531 print_bad_pte(vma, address, orig_pte, NULL); 2532 ret = VM_FAULT_SIGBUS; 2533 } 2534 goto out; 2535 } 2536 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2537 page = lookup_swap_cache(entry); 2538 if (!page) { 2539 grab_swap_token(mm); /* Contend for token _before_ read-in */ 2540 page = swapin_readahead(entry, 2541 GFP_HIGHUSER_MOVABLE, vma, address); 2542 if (!page) { 2543 /* 2544 * Back out if somebody else faulted in this pte 2545 * while we released the pte lock. 2546 */ 2547 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2548 if (likely(pte_same(*page_table, orig_pte))) 2549 ret = VM_FAULT_OOM; 2550 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2551 goto unlock; 2552 } 2553 2554 /* Had to read the page from swap area: Major fault */ 2555 ret = VM_FAULT_MAJOR; 2556 count_vm_event(PGMAJFAULT); 2557 } else if (PageHWPoison(page)) { 2558 /* 2559 * hwpoisoned dirty swapcache pages are kept for killing 2560 * owner processes (which may be unknown at hwpoison time) 2561 */ 2562 ret = VM_FAULT_HWPOISON; 2563 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2564 goto out_release; 2565 } 2566 2567 lock_page(page); 2568 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2569 2570 page = ksm_might_need_to_copy(page, vma, address); 2571 if (!page) { 2572 ret = VM_FAULT_OOM; 2573 goto out; 2574 } 2575 2576 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { 2577 ret = VM_FAULT_OOM; 2578 goto out_page; 2579 } 2580 2581 /* 2582 * Back out if somebody else already faulted in this pte. 2583 */ 2584 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2585 if (unlikely(!pte_same(*page_table, orig_pte))) 2586 goto out_nomap; 2587 2588 if (unlikely(!PageUptodate(page))) { 2589 ret = VM_FAULT_SIGBUS; 2590 goto out_nomap; 2591 } 2592 2593 /* 2594 * The page isn't present yet, go ahead with the fault. 2595 * 2596 * Be careful about the sequence of operations here. 2597 * To get its accounting right, reuse_swap_page() must be called 2598 * while the page is counted on swap but not yet in mapcount i.e. 2599 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2600 * must be called after the swap_free(), or it will never succeed. 2601 * Because delete_from_swap_page() may be called by reuse_swap_page(), 2602 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry 2603 * in page->private. In this case, a record in swap_cgroup is silently 2604 * discarded at swap_free(). 2605 */ 2606 2607 inc_mm_counter(mm, anon_rss); 2608 pte = mk_pte(page, vma->vm_page_prot); 2609 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 2610 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2611 flags &= ~FAULT_FLAG_WRITE; 2612 } 2613 flush_icache_page(vma, page); 2614 set_pte_at(mm, address, page_table, pte); 2615 page_add_anon_rmap(page, vma, address); 2616 /* It's better to call commit-charge after rmap is established */ 2617 mem_cgroup_commit_charge_swapin(page, ptr); 2618 2619 swap_free(entry); 2620 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 2621 try_to_free_swap(page); 2622 unlock_page(page); 2623 2624 if (flags & FAULT_FLAG_WRITE) { 2625 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 2626 if (ret & VM_FAULT_ERROR) 2627 ret &= VM_FAULT_ERROR; 2628 goto out; 2629 } 2630 2631 /* No need to invalidate - it was non-present before */ 2632 update_mmu_cache(vma, address, pte); 2633 unlock: 2634 pte_unmap_unlock(page_table, ptl); 2635 out: 2636 return ret; 2637 out_nomap: 2638 mem_cgroup_cancel_charge_swapin(ptr); 2639 pte_unmap_unlock(page_table, ptl); 2640 out_page: 2641 unlock_page(page); 2642 out_release: 2643 page_cache_release(page); 2644 return ret; 2645 } 2646 2647 /* 2648 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2649 * but allow concurrent faults), and pte mapped but not yet locked. 2650 * We return with mmap_sem still held, but pte unmapped and unlocked. 2651 */ 2652 static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2653 unsigned long address, pte_t *page_table, pmd_t *pmd, 2654 unsigned int flags) 2655 { 2656 struct page *page; 2657 spinlock_t *ptl; 2658 pte_t entry; 2659 2660 if (!(flags & FAULT_FLAG_WRITE)) { 2661 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address), 2662 vma->vm_page_prot)); 2663 ptl = pte_lockptr(mm, pmd); 2664 spin_lock(ptl); 2665 if (!pte_none(*page_table)) 2666 goto unlock; 2667 goto setpte; 2668 } 2669 2670 /* Allocate our own private page. */ 2671 pte_unmap(page_table); 2672 2673 if (unlikely(anon_vma_prepare(vma))) 2674 goto oom; 2675 page = alloc_zeroed_user_highpage_movable(vma, address); 2676 if (!page) 2677 goto oom; 2678 __SetPageUptodate(page); 2679 2680 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) 2681 goto oom_free_page; 2682 2683 entry = mk_pte(page, vma->vm_page_prot); 2684 if (vma->vm_flags & VM_WRITE) 2685 entry = pte_mkwrite(pte_mkdirty(entry)); 2686 2687 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2688 if (!pte_none(*page_table)) 2689 goto release; 2690 2691 inc_mm_counter(mm, anon_rss); 2692 page_add_new_anon_rmap(page, vma, address); 2693 setpte: 2694 set_pte_at(mm, address, page_table, entry); 2695 2696 /* No need to invalidate - it was non-present before */ 2697 update_mmu_cache(vma, address, entry); 2698 unlock: 2699 pte_unmap_unlock(page_table, ptl); 2700 return 0; 2701 release: 2702 mem_cgroup_uncharge_page(page); 2703 page_cache_release(page); 2704 goto unlock; 2705 oom_free_page: 2706 page_cache_release(page); 2707 oom: 2708 return VM_FAULT_OOM; 2709 } 2710 2711 /* 2712 * __do_fault() tries to create a new page mapping. It aggressively 2713 * tries to share with existing pages, but makes a separate copy if 2714 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 2715 * the next page fault. 2716 * 2717 * As this is called only for pages that do not currently exist, we 2718 * do not need to flush old virtual caches or the TLB. 2719 * 2720 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2721 * but allow concurrent faults), and pte neither mapped nor locked. 2722 * We return with mmap_sem still held, but pte unmapped and unlocked. 2723 */ 2724 static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2725 unsigned long address, pmd_t *pmd, 2726 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2727 { 2728 pte_t *page_table; 2729 spinlock_t *ptl; 2730 struct page *page; 2731 pte_t entry; 2732 int anon = 0; 2733 int charged = 0; 2734 struct page *dirty_page = NULL; 2735 struct vm_fault vmf; 2736 int ret; 2737 int page_mkwrite = 0; 2738 2739 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2740 vmf.pgoff = pgoff; 2741 vmf.flags = flags; 2742 vmf.page = NULL; 2743 2744 ret = vma->vm_ops->fault(vma, &vmf); 2745 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2746 return ret; 2747 2748 if (unlikely(PageHWPoison(vmf.page))) { 2749 if (ret & VM_FAULT_LOCKED) 2750 unlock_page(vmf.page); 2751 return VM_FAULT_HWPOISON; 2752 } 2753 2754 /* 2755 * For consistency in subsequent calls, make the faulted page always 2756 * locked. 2757 */ 2758 if (unlikely(!(ret & VM_FAULT_LOCKED))) 2759 lock_page(vmf.page); 2760 else 2761 VM_BUG_ON(!PageLocked(vmf.page)); 2762 2763 /* 2764 * Should we do an early C-O-W break? 2765 */ 2766 page = vmf.page; 2767 if (flags & FAULT_FLAG_WRITE) { 2768 if (!(vma->vm_flags & VM_SHARED)) { 2769 anon = 1; 2770 if (unlikely(anon_vma_prepare(vma))) { 2771 ret = VM_FAULT_OOM; 2772 goto out; 2773 } 2774 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, 2775 vma, address); 2776 if (!page) { 2777 ret = VM_FAULT_OOM; 2778 goto out; 2779 } 2780 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) { 2781 ret = VM_FAULT_OOM; 2782 page_cache_release(page); 2783 goto out; 2784 } 2785 charged = 1; 2786 /* 2787 * Don't let another task, with possibly unlocked vma, 2788 * keep the mlocked page. 2789 */ 2790 if (vma->vm_flags & VM_LOCKED) 2791 clear_page_mlock(vmf.page); 2792 copy_user_highpage(page, vmf.page, address, vma); 2793 __SetPageUptodate(page); 2794 } else { 2795 /* 2796 * If the page will be shareable, see if the backing 2797 * address space wants to know that the page is about 2798 * to become writable 2799 */ 2800 if (vma->vm_ops->page_mkwrite) { 2801 int tmp; 2802 2803 unlock_page(page); 2804 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2805 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 2806 if (unlikely(tmp & 2807 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2808 ret = tmp; 2809 goto unwritable_page; 2810 } 2811 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 2812 lock_page(page); 2813 if (!page->mapping) { 2814 ret = 0; /* retry the fault */ 2815 unlock_page(page); 2816 goto unwritable_page; 2817 } 2818 } else 2819 VM_BUG_ON(!PageLocked(page)); 2820 page_mkwrite = 1; 2821 } 2822 } 2823 2824 } 2825 2826 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2827 2828 /* 2829 * This silly early PAGE_DIRTY setting removes a race 2830 * due to the bad i386 page protection. But it's valid 2831 * for other architectures too. 2832 * 2833 * Note that if FAULT_FLAG_WRITE is set, we either now have 2834 * an exclusive copy of the page, or this is a shared mapping, 2835 * so we can make it writable and dirty to avoid having to 2836 * handle that later. 2837 */ 2838 /* Only go through if we didn't race with anybody else... */ 2839 if (likely(pte_same(*page_table, orig_pte))) { 2840 flush_icache_page(vma, page); 2841 entry = mk_pte(page, vma->vm_page_prot); 2842 if (flags & FAULT_FLAG_WRITE) 2843 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2844 if (anon) { 2845 inc_mm_counter(mm, anon_rss); 2846 page_add_new_anon_rmap(page, vma, address); 2847 } else { 2848 inc_mm_counter(mm, file_rss); 2849 page_add_file_rmap(page); 2850 if (flags & FAULT_FLAG_WRITE) { 2851 dirty_page = page; 2852 get_page(dirty_page); 2853 } 2854 } 2855 set_pte_at(mm, address, page_table, entry); 2856 2857 /* no need to invalidate: a not-present page won't be cached */ 2858 update_mmu_cache(vma, address, entry); 2859 } else { 2860 if (charged) 2861 mem_cgroup_uncharge_page(page); 2862 if (anon) 2863 page_cache_release(page); 2864 else 2865 anon = 1; /* no anon but release faulted_page */ 2866 } 2867 2868 pte_unmap_unlock(page_table, ptl); 2869 2870 out: 2871 if (dirty_page) { 2872 struct address_space *mapping = page->mapping; 2873 2874 if (set_page_dirty(dirty_page)) 2875 page_mkwrite = 1; 2876 unlock_page(dirty_page); 2877 put_page(dirty_page); 2878 if (page_mkwrite && mapping) { 2879 /* 2880 * Some device drivers do not set page.mapping but still 2881 * dirty their pages 2882 */ 2883 balance_dirty_pages_ratelimited(mapping); 2884 } 2885 2886 /* file_update_time outside page_lock */ 2887 if (vma->vm_file) 2888 file_update_time(vma->vm_file); 2889 } else { 2890 unlock_page(vmf.page); 2891 if (anon) 2892 page_cache_release(vmf.page); 2893 } 2894 2895 return ret; 2896 2897 unwritable_page: 2898 page_cache_release(page); 2899 return ret; 2900 } 2901 2902 static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2903 unsigned long address, pte_t *page_table, pmd_t *pmd, 2904 unsigned int flags, pte_t orig_pte) 2905 { 2906 pgoff_t pgoff = (((address & PAGE_MASK) 2907 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 2908 2909 pte_unmap(page_table); 2910 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2911 } 2912 2913 /* 2914 * Fault of a previously existing named mapping. Repopulate the pte 2915 * from the encoded file_pte if possible. This enables swappable 2916 * nonlinear vmas. 2917 * 2918 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2919 * but allow concurrent faults), and pte mapped but not yet locked. 2920 * We return with mmap_sem still held, but pte unmapped and unlocked. 2921 */ 2922 static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2923 unsigned long address, pte_t *page_table, pmd_t *pmd, 2924 unsigned int flags, pte_t orig_pte) 2925 { 2926 pgoff_t pgoff; 2927 2928 flags |= FAULT_FLAG_NONLINEAR; 2929 2930 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2931 return 0; 2932 2933 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 2934 /* 2935 * Page table corrupted: show pte and kill process. 2936 */ 2937 print_bad_pte(vma, address, orig_pte, NULL); 2938 return VM_FAULT_SIGBUS; 2939 } 2940 2941 pgoff = pte_to_pgoff(orig_pte); 2942 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2943 } 2944 2945 /* 2946 * These routines also need to handle stuff like marking pages dirty 2947 * and/or accessed for architectures that don't do it in hardware (most 2948 * RISC architectures). The early dirtying is also good on the i386. 2949 * 2950 * There is also a hook called "update_mmu_cache()" that architectures 2951 * with external mmu caches can use to update those (ie the Sparc or 2952 * PowerPC hashed page tables that act as extended TLBs). 2953 * 2954 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2955 * but allow concurrent faults), and pte mapped but not yet locked. 2956 * We return with mmap_sem still held, but pte unmapped and unlocked. 2957 */ 2958 static inline int handle_pte_fault(struct mm_struct *mm, 2959 struct vm_area_struct *vma, unsigned long address, 2960 pte_t *pte, pmd_t *pmd, unsigned int flags) 2961 { 2962 pte_t entry; 2963 spinlock_t *ptl; 2964 2965 entry = *pte; 2966 if (!pte_present(entry)) { 2967 if (pte_none(entry)) { 2968 if (vma->vm_ops) { 2969 if (likely(vma->vm_ops->fault)) 2970 return do_linear_fault(mm, vma, address, 2971 pte, pmd, flags, entry); 2972 } 2973 return do_anonymous_page(mm, vma, address, 2974 pte, pmd, flags); 2975 } 2976 if (pte_file(entry)) 2977 return do_nonlinear_fault(mm, vma, address, 2978 pte, pmd, flags, entry); 2979 return do_swap_page(mm, vma, address, 2980 pte, pmd, flags, entry); 2981 } 2982 2983 ptl = pte_lockptr(mm, pmd); 2984 spin_lock(ptl); 2985 if (unlikely(!pte_same(*pte, entry))) 2986 goto unlock; 2987 if (flags & FAULT_FLAG_WRITE) { 2988 if (!pte_write(entry)) 2989 return do_wp_page(mm, vma, address, 2990 pte, pmd, ptl, entry); 2991 entry = pte_mkdirty(entry); 2992 } 2993 entry = pte_mkyoung(entry); 2994 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 2995 update_mmu_cache(vma, address, entry); 2996 } else { 2997 /* 2998 * This is needed only for protection faults but the arch code 2999 * is not yet telling us if this is a protection fault or not. 3000 * This still avoids useless tlb flushes for .text page faults 3001 * with threads. 3002 */ 3003 if (flags & FAULT_FLAG_WRITE) 3004 flush_tlb_page(vma, address); 3005 } 3006 unlock: 3007 pte_unmap_unlock(pte, ptl); 3008 return 0; 3009 } 3010 3011 /* 3012 * By the time we get here, we already hold the mm semaphore 3013 */ 3014 int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 3015 unsigned long address, unsigned int flags) 3016 { 3017 pgd_t *pgd; 3018 pud_t *pud; 3019 pmd_t *pmd; 3020 pte_t *pte; 3021 3022 __set_current_state(TASK_RUNNING); 3023 3024 count_vm_event(PGFAULT); 3025 3026 if (unlikely(is_vm_hugetlb_page(vma))) 3027 return hugetlb_fault(mm, vma, address, flags); 3028 3029 pgd = pgd_offset(mm, address); 3030 pud = pud_alloc(mm, pgd, address); 3031 if (!pud) 3032 return VM_FAULT_OOM; 3033 pmd = pmd_alloc(mm, pud, address); 3034 if (!pmd) 3035 return VM_FAULT_OOM; 3036 pte = pte_alloc_map(mm, pmd, address); 3037 if (!pte) 3038 return VM_FAULT_OOM; 3039 3040 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 3041 } 3042 3043 #ifndef __PAGETABLE_PUD_FOLDED 3044 /* 3045 * Allocate page upper directory. 3046 * We've already handled the fast-path in-line. 3047 */ 3048 int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3049 { 3050 pud_t *new = pud_alloc_one(mm, address); 3051 if (!new) 3052 return -ENOMEM; 3053 3054 smp_wmb(); /* See comment in __pte_alloc */ 3055 3056 spin_lock(&mm->page_table_lock); 3057 if (pgd_present(*pgd)) /* Another has populated it */ 3058 pud_free(mm, new); 3059 else 3060 pgd_populate(mm, pgd, new); 3061 spin_unlock(&mm->page_table_lock); 3062 return 0; 3063 } 3064 #endif /* __PAGETABLE_PUD_FOLDED */ 3065 3066 #ifndef __PAGETABLE_PMD_FOLDED 3067 /* 3068 * Allocate page middle directory. 3069 * We've already handled the fast-path in-line. 3070 */ 3071 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 3072 { 3073 pmd_t *new = pmd_alloc_one(mm, address); 3074 if (!new) 3075 return -ENOMEM; 3076 3077 smp_wmb(); /* See comment in __pte_alloc */ 3078 3079 spin_lock(&mm->page_table_lock); 3080 #ifndef __ARCH_HAS_4LEVEL_HACK 3081 if (pud_present(*pud)) /* Another has populated it */ 3082 pmd_free(mm, new); 3083 else 3084 pud_populate(mm, pud, new); 3085 #else 3086 if (pgd_present(*pud)) /* Another has populated it */ 3087 pmd_free(mm, new); 3088 else 3089 pgd_populate(mm, pud, new); 3090 #endif /* __ARCH_HAS_4LEVEL_HACK */ 3091 spin_unlock(&mm->page_table_lock); 3092 return 0; 3093 } 3094 #endif /* __PAGETABLE_PMD_FOLDED */ 3095 3096 int make_pages_present(unsigned long addr, unsigned long end) 3097 { 3098 int ret, len, write; 3099 struct vm_area_struct * vma; 3100 3101 vma = find_vma(current->mm, addr); 3102 if (!vma) 3103 return -ENOMEM; 3104 write = (vma->vm_flags & VM_WRITE) != 0; 3105 BUG_ON(addr >= end); 3106 BUG_ON(end > vma->vm_end); 3107 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; 3108 ret = get_user_pages(current, current->mm, addr, 3109 len, write, 0, NULL, NULL); 3110 if (ret < 0) 3111 return ret; 3112 return ret == len ? 0 : -EFAULT; 3113 } 3114 3115 #if !defined(__HAVE_ARCH_GATE_AREA) 3116 3117 #if defined(AT_SYSINFO_EHDR) 3118 static struct vm_area_struct gate_vma; 3119 3120 static int __init gate_vma_init(void) 3121 { 3122 gate_vma.vm_mm = NULL; 3123 gate_vma.vm_start = FIXADDR_USER_START; 3124 gate_vma.vm_end = FIXADDR_USER_END; 3125 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 3126 gate_vma.vm_page_prot = __P101; 3127 /* 3128 * Make sure the vDSO gets into every core dump. 3129 * Dumping its contents makes post-mortem fully interpretable later 3130 * without matching up the same kernel and hardware config to see 3131 * what PC values meant. 3132 */ 3133 gate_vma.vm_flags |= VM_ALWAYSDUMP; 3134 return 0; 3135 } 3136 __initcall(gate_vma_init); 3137 #endif 3138 3139 struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 3140 { 3141 #ifdef AT_SYSINFO_EHDR 3142 return &gate_vma; 3143 #else 3144 return NULL; 3145 #endif 3146 } 3147 3148 int in_gate_area_no_task(unsigned long addr) 3149 { 3150 #ifdef AT_SYSINFO_EHDR 3151 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 3152 return 1; 3153 #endif 3154 return 0; 3155 } 3156 3157 #endif /* __HAVE_ARCH_GATE_AREA */ 3158 3159 static int follow_pte(struct mm_struct *mm, unsigned long address, 3160 pte_t **ptepp, spinlock_t **ptlp) 3161 { 3162 pgd_t *pgd; 3163 pud_t *pud; 3164 pmd_t *pmd; 3165 pte_t *ptep; 3166 3167 pgd = pgd_offset(mm, address); 3168 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 3169 goto out; 3170 3171 pud = pud_offset(pgd, address); 3172 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 3173 goto out; 3174 3175 pmd = pmd_offset(pud, address); 3176 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 3177 goto out; 3178 3179 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 3180 if (pmd_huge(*pmd)) 3181 goto out; 3182 3183 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 3184 if (!ptep) 3185 goto out; 3186 if (!pte_present(*ptep)) 3187 goto unlock; 3188 *ptepp = ptep; 3189 return 0; 3190 unlock: 3191 pte_unmap_unlock(ptep, *ptlp); 3192 out: 3193 return -EINVAL; 3194 } 3195 3196 /** 3197 * follow_pfn - look up PFN at a user virtual address 3198 * @vma: memory mapping 3199 * @address: user virtual address 3200 * @pfn: location to store found PFN 3201 * 3202 * Only IO mappings and raw PFN mappings are allowed. 3203 * 3204 * Returns zero and the pfn at @pfn on success, -ve otherwise. 3205 */ 3206 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 3207 unsigned long *pfn) 3208 { 3209 int ret = -EINVAL; 3210 spinlock_t *ptl; 3211 pte_t *ptep; 3212 3213 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3214 return ret; 3215 3216 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 3217 if (ret) 3218 return ret; 3219 *pfn = pte_pfn(*ptep); 3220 pte_unmap_unlock(ptep, ptl); 3221 return 0; 3222 } 3223 EXPORT_SYMBOL(follow_pfn); 3224 3225 #ifdef CONFIG_HAVE_IOREMAP_PROT 3226 int follow_phys(struct vm_area_struct *vma, 3227 unsigned long address, unsigned int flags, 3228 unsigned long *prot, resource_size_t *phys) 3229 { 3230 int ret = -EINVAL; 3231 pte_t *ptep, pte; 3232 spinlock_t *ptl; 3233 3234 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3235 goto out; 3236 3237 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 3238 goto out; 3239 pte = *ptep; 3240 3241 if ((flags & FOLL_WRITE) && !pte_write(pte)) 3242 goto unlock; 3243 3244 *prot = pgprot_val(pte_pgprot(pte)); 3245 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 3246 3247 ret = 0; 3248 unlock: 3249 pte_unmap_unlock(ptep, ptl); 3250 out: 3251 return ret; 3252 } 3253 3254 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 3255 void *buf, int len, int write) 3256 { 3257 resource_size_t phys_addr; 3258 unsigned long prot = 0; 3259 void __iomem *maddr; 3260 int offset = addr & (PAGE_SIZE-1); 3261 3262 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 3263 return -EINVAL; 3264 3265 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 3266 if (write) 3267 memcpy_toio(maddr + offset, buf, len); 3268 else 3269 memcpy_fromio(buf, maddr + offset, len); 3270 iounmap(maddr); 3271 3272 return len; 3273 } 3274 #endif 3275 3276 /* 3277 * Access another process' address space. 3278 * Source/target buffer must be kernel space, 3279 * Do not walk the page table directly, use get_user_pages 3280 */ 3281 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 3282 { 3283 struct mm_struct *mm; 3284 struct vm_area_struct *vma; 3285 void *old_buf = buf; 3286 3287 mm = get_task_mm(tsk); 3288 if (!mm) 3289 return 0; 3290 3291 down_read(&mm->mmap_sem); 3292 /* ignore errors, just check how much was successfully transferred */ 3293 while (len) { 3294 int bytes, ret, offset; 3295 void *maddr; 3296 struct page *page = NULL; 3297 3298 ret = get_user_pages(tsk, mm, addr, 1, 3299 write, 1, &page, &vma); 3300 if (ret <= 0) { 3301 /* 3302 * Check if this is a VM_IO | VM_PFNMAP VMA, which 3303 * we can access using slightly different code. 3304 */ 3305 #ifdef CONFIG_HAVE_IOREMAP_PROT 3306 vma = find_vma(mm, addr); 3307 if (!vma) 3308 break; 3309 if (vma->vm_ops && vma->vm_ops->access) 3310 ret = vma->vm_ops->access(vma, addr, buf, 3311 len, write); 3312 if (ret <= 0) 3313 #endif 3314 break; 3315 bytes = ret; 3316 } else { 3317 bytes = len; 3318 offset = addr & (PAGE_SIZE-1); 3319 if (bytes > PAGE_SIZE-offset) 3320 bytes = PAGE_SIZE-offset; 3321 3322 maddr = kmap(page); 3323 if (write) { 3324 copy_to_user_page(vma, page, addr, 3325 maddr + offset, buf, bytes); 3326 set_page_dirty_lock(page); 3327 } else { 3328 copy_from_user_page(vma, page, addr, 3329 buf, maddr + offset, bytes); 3330 } 3331 kunmap(page); 3332 page_cache_release(page); 3333 } 3334 len -= bytes; 3335 buf += bytes; 3336 addr += bytes; 3337 } 3338 up_read(&mm->mmap_sem); 3339 mmput(mm); 3340 3341 return buf - old_buf; 3342 } 3343 3344 /* 3345 * Print the name of a VMA. 3346 */ 3347 void print_vma_addr(char *prefix, unsigned long ip) 3348 { 3349 struct mm_struct *mm = current->mm; 3350 struct vm_area_struct *vma; 3351 3352 /* 3353 * Do not print if we are in atomic 3354 * contexts (in exception stacks, etc.): 3355 */ 3356 if (preempt_count()) 3357 return; 3358 3359 down_read(&mm->mmap_sem); 3360 vma = find_vma(mm, ip); 3361 if (vma && vma->vm_file) { 3362 struct file *f = vma->vm_file; 3363 char *buf = (char *)__get_free_page(GFP_KERNEL); 3364 if (buf) { 3365 char *p, *s; 3366 3367 p = d_path(&f->f_path, buf, PAGE_SIZE); 3368 if (IS_ERR(p)) 3369 p = "?"; 3370 s = strrchr(p, '/'); 3371 if (s) 3372 p = s+1; 3373 printk("%s%s[%lx+%lx]", prefix, p, 3374 vma->vm_start, 3375 vma->vm_end - vma->vm_start); 3376 free_page((unsigned long)buf); 3377 } 3378 } 3379 up_read(¤t->mm->mmap_sem); 3380 } 3381 3382 #ifdef CONFIG_PROVE_LOCKING 3383 void might_fault(void) 3384 { 3385 /* 3386 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 3387 * holding the mmap_sem, this is safe because kernel memory doesn't 3388 * get paged out, therefore we'll never actually fault, and the 3389 * below annotations will generate false positives. 3390 */ 3391 if (segment_eq(get_fs(), KERNEL_DS)) 3392 return; 3393 3394 might_sleep(); 3395 /* 3396 * it would be nicer only to annotate paths which are not under 3397 * pagefault_disable, however that requires a larger audit and 3398 * providing helpers like get_user_atomic. 3399 */ 3400 if (!in_atomic() && current->mm) 3401 might_lock_read(¤t->mm->mmap_sem); 3402 } 3403 EXPORT_SYMBOL(might_fault); 3404 #endif 3405