memory.c revision 828502d30073036a486d96b1fe051e0f08b6df83
1/* 2 * linux/mm/memory.c 3 * 4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 5 */ 6 7/* 8 * demand-loading started 01.12.91 - seems it is high on the list of 9 * things wanted, and it should be easy to implement. - Linus 10 */ 11 12/* 13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared 14 * pages started 02.12.91, seems to work. - Linus. 15 * 16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it 17 * would have taken more than the 6M I have free, but it worked well as 18 * far as I could see. 19 * 20 * Also corrected some "invalidate()"s - I wasn't doing enough of them. 21 */ 22 23/* 24 * Real VM (paging to/from disk) started 18.12.91. Much more work and 25 * thought has to go into this. Oh, well.. 26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why. 27 * Found it. Everything seems to work now. 28 * 20.12.91 - Ok, making the swap-device changeable like the root. 29 */ 30 31/* 32 * 05.04.94 - Multi-page memory management added for v1.1. 33 * Idea by Alex Bligh (alex@cconcepts.co.uk) 34 * 35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG 36 * (Gerhard.Wichert@pdb.siemens.de) 37 * 38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen) 39 */ 40 41#include <linux/kernel_stat.h> 42#include <linux/mm.h> 43#include <linux/hugetlb.h> 44#include <linux/mman.h> 45#include <linux/swap.h> 46#include <linux/highmem.h> 47#include <linux/pagemap.h> 48#include <linux/rmap.h> 49#include <linux/module.h> 50#include <linux/delayacct.h> 51#include <linux/init.h> 52#include <linux/writeback.h> 53#include <linux/memcontrol.h> 54#include <linux/mmu_notifier.h> 55#include <linux/kallsyms.h> 56#include <linux/swapops.h> 57#include <linux/elf.h> 58 59#include <asm/io.h> 60#include <asm/pgalloc.h> 61#include <asm/uaccess.h> 62#include <asm/tlb.h> 63#include <asm/tlbflush.h> 64#include <asm/pgtable.h> 65 66#include "internal.h" 67 68#ifndef CONFIG_NEED_MULTIPLE_NODES 69/* use the per-pgdat data instead for discontigmem - mbligh */ 70unsigned long max_mapnr; 71struct page *mem_map; 72 73EXPORT_SYMBOL(max_mapnr); 74EXPORT_SYMBOL(mem_map); 75#endif 76 77unsigned long num_physpages; 78/* 79 * A number of key systems in x86 including ioremap() rely on the assumption 80 * that high_memory defines the upper bound on direct map memory, then end 81 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and 82 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL 83 * and ZONE_HIGHMEM. 84 */ 85void * high_memory; 86 87EXPORT_SYMBOL(num_physpages); 88EXPORT_SYMBOL(high_memory); 89 90/* 91 * Randomize the address space (stacks, mmaps, brk, etc.). 92 * 93 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization, 94 * as ancient (libc5 based) binaries can segfault. ) 95 */ 96int randomize_va_space __read_mostly = 97#ifdef CONFIG_COMPAT_BRK 98 1; 99#else 100 2; 101#endif 102 103static int __init disable_randmaps(char *s) 104{ 105 randomize_va_space = 0; 106 return 1; 107} 108__setup("norandmaps", disable_randmaps); 109 110 111/* 112 * If a p?d_bad entry is found while walking page tables, report 113 * the error, before resetting entry to p?d_none. Usually (but 114 * very seldom) called out from the p?d_none_or_clear_bad macros. 115 */ 116 117void pgd_clear_bad(pgd_t *pgd) 118{ 119 pgd_ERROR(*pgd); 120 pgd_clear(pgd); 121} 122 123void pud_clear_bad(pud_t *pud) 124{ 125 pud_ERROR(*pud); 126 pud_clear(pud); 127} 128 129void pmd_clear_bad(pmd_t *pmd) 130{ 131 pmd_ERROR(*pmd); 132 pmd_clear(pmd); 133} 134 135/* 136 * Note: this doesn't free the actual pages themselves. That 137 * has been handled earlier when unmapping all the memory regions. 138 */ 139static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd, 140 unsigned long addr) 141{ 142 pgtable_t token = pmd_pgtable(*pmd); 143 pmd_clear(pmd); 144 pte_free_tlb(tlb, token, addr); 145 tlb->mm->nr_ptes--; 146} 147 148static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud, 149 unsigned long addr, unsigned long end, 150 unsigned long floor, unsigned long ceiling) 151{ 152 pmd_t *pmd; 153 unsigned long next; 154 unsigned long start; 155 156 start = addr; 157 pmd = pmd_offset(pud, addr); 158 do { 159 next = pmd_addr_end(addr, end); 160 if (pmd_none_or_clear_bad(pmd)) 161 continue; 162 free_pte_range(tlb, pmd, addr); 163 } while (pmd++, addr = next, addr != end); 164 165 start &= PUD_MASK; 166 if (start < floor) 167 return; 168 if (ceiling) { 169 ceiling &= PUD_MASK; 170 if (!ceiling) 171 return; 172 } 173 if (end - 1 > ceiling - 1) 174 return; 175 176 pmd = pmd_offset(pud, start); 177 pud_clear(pud); 178 pmd_free_tlb(tlb, pmd, start); 179} 180 181static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd, 182 unsigned long addr, unsigned long end, 183 unsigned long floor, unsigned long ceiling) 184{ 185 pud_t *pud; 186 unsigned long next; 187 unsigned long start; 188 189 start = addr; 190 pud = pud_offset(pgd, addr); 191 do { 192 next = pud_addr_end(addr, end); 193 if (pud_none_or_clear_bad(pud)) 194 continue; 195 free_pmd_range(tlb, pud, addr, next, floor, ceiling); 196 } while (pud++, addr = next, addr != end); 197 198 start &= PGDIR_MASK; 199 if (start < floor) 200 return; 201 if (ceiling) { 202 ceiling &= PGDIR_MASK; 203 if (!ceiling) 204 return; 205 } 206 if (end - 1 > ceiling - 1) 207 return; 208 209 pud = pud_offset(pgd, start); 210 pgd_clear(pgd); 211 pud_free_tlb(tlb, pud, start); 212} 213 214/* 215 * This function frees user-level page tables of a process. 216 * 217 * Must be called with pagetable lock held. 218 */ 219void free_pgd_range(struct mmu_gather *tlb, 220 unsigned long addr, unsigned long end, 221 unsigned long floor, unsigned long ceiling) 222{ 223 pgd_t *pgd; 224 unsigned long next; 225 unsigned long start; 226 227 /* 228 * The next few lines have given us lots of grief... 229 * 230 * Why are we testing PMD* at this top level? Because often 231 * there will be no work to do at all, and we'd prefer not to 232 * go all the way down to the bottom just to discover that. 233 * 234 * Why all these "- 1"s? Because 0 represents both the bottom 235 * of the address space and the top of it (using -1 for the 236 * top wouldn't help much: the masks would do the wrong thing). 237 * The rule is that addr 0 and floor 0 refer to the bottom of 238 * the address space, but end 0 and ceiling 0 refer to the top 239 * Comparisons need to use "end - 1" and "ceiling - 1" (though 240 * that end 0 case should be mythical). 241 * 242 * Wherever addr is brought up or ceiling brought down, we must 243 * be careful to reject "the opposite 0" before it confuses the 244 * subsequent tests. But what about where end is brought down 245 * by PMD_SIZE below? no, end can't go down to 0 there. 246 * 247 * Whereas we round start (addr) and ceiling down, by different 248 * masks at different levels, in order to test whether a table 249 * now has no other vmas using it, so can be freed, we don't 250 * bother to round floor or end up - the tests don't need that. 251 */ 252 253 addr &= PMD_MASK; 254 if (addr < floor) { 255 addr += PMD_SIZE; 256 if (!addr) 257 return; 258 } 259 if (ceiling) { 260 ceiling &= PMD_MASK; 261 if (!ceiling) 262 return; 263 } 264 if (end - 1 > ceiling - 1) 265 end -= PMD_SIZE; 266 if (addr > end - 1) 267 return; 268 269 start = addr; 270 pgd = pgd_offset(tlb->mm, addr); 271 do { 272 next = pgd_addr_end(addr, end); 273 if (pgd_none_or_clear_bad(pgd)) 274 continue; 275 free_pud_range(tlb, pgd, addr, next, floor, ceiling); 276 } while (pgd++, addr = next, addr != end); 277} 278 279void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma, 280 unsigned long floor, unsigned long ceiling) 281{ 282 while (vma) { 283 struct vm_area_struct *next = vma->vm_next; 284 unsigned long addr = vma->vm_start; 285 286 /* 287 * Hide vma from rmap and vmtruncate before freeing pgtables 288 */ 289 anon_vma_unlink(vma); 290 unlink_file_vma(vma); 291 292 if (is_vm_hugetlb_page(vma)) { 293 hugetlb_free_pgd_range(tlb, addr, vma->vm_end, 294 floor, next? next->vm_start: ceiling); 295 } else { 296 /* 297 * Optimization: gather nearby vmas into one call down 298 */ 299 while (next && next->vm_start <= vma->vm_end + PMD_SIZE 300 && !is_vm_hugetlb_page(next)) { 301 vma = next; 302 next = vma->vm_next; 303 anon_vma_unlink(vma); 304 unlink_file_vma(vma); 305 } 306 free_pgd_range(tlb, addr, vma->vm_end, 307 floor, next? next->vm_start: ceiling); 308 } 309 vma = next; 310 } 311} 312 313int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address) 314{ 315 pgtable_t new = pte_alloc_one(mm, address); 316 if (!new) 317 return -ENOMEM; 318 319 /* 320 * Ensure all pte setup (eg. pte page lock and page clearing) are 321 * visible before the pte is made visible to other CPUs by being 322 * put into page tables. 323 * 324 * The other side of the story is the pointer chasing in the page 325 * table walking code (when walking the page table without locking; 326 * ie. most of the time). Fortunately, these data accesses consist 327 * of a chain of data-dependent loads, meaning most CPUs (alpha 328 * being the notable exception) will already guarantee loads are 329 * seen in-order. See the alpha page table accessors for the 330 * smp_read_barrier_depends() barriers in page table walking code. 331 */ 332 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */ 333 334 spin_lock(&mm->page_table_lock); 335 if (!pmd_present(*pmd)) { /* Has another populated it ? */ 336 mm->nr_ptes++; 337 pmd_populate(mm, pmd, new); 338 new = NULL; 339 } 340 spin_unlock(&mm->page_table_lock); 341 if (new) 342 pte_free(mm, new); 343 return 0; 344} 345 346int __pte_alloc_kernel(pmd_t *pmd, unsigned long address) 347{ 348 pte_t *new = pte_alloc_one_kernel(&init_mm, address); 349 if (!new) 350 return -ENOMEM; 351 352 smp_wmb(); /* See comment in __pte_alloc */ 353 354 spin_lock(&init_mm.page_table_lock); 355 if (!pmd_present(*pmd)) { /* Has another populated it ? */ 356 pmd_populate_kernel(&init_mm, pmd, new); 357 new = NULL; 358 } 359 spin_unlock(&init_mm.page_table_lock); 360 if (new) 361 pte_free_kernel(&init_mm, new); 362 return 0; 363} 364 365static inline void add_mm_rss(struct mm_struct *mm, int file_rss, int anon_rss) 366{ 367 if (file_rss) 368 add_mm_counter(mm, file_rss, file_rss); 369 if (anon_rss) 370 add_mm_counter(mm, anon_rss, anon_rss); 371} 372 373/* 374 * This function is called to print an error when a bad pte 375 * is found. For example, we might have a PFN-mapped pte in 376 * a region that doesn't allow it. 377 * 378 * The calling function must still handle the error. 379 */ 380static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, 381 pte_t pte, struct page *page) 382{ 383 pgd_t *pgd = pgd_offset(vma->vm_mm, addr); 384 pud_t *pud = pud_offset(pgd, addr); 385 pmd_t *pmd = pmd_offset(pud, addr); 386 struct address_space *mapping; 387 pgoff_t index; 388 static unsigned long resume; 389 static unsigned long nr_shown; 390 static unsigned long nr_unshown; 391 392 /* 393 * Allow a burst of 60 reports, then keep quiet for that minute; 394 * or allow a steady drip of one report per second. 395 */ 396 if (nr_shown == 60) { 397 if (time_before(jiffies, resume)) { 398 nr_unshown++; 399 return; 400 } 401 if (nr_unshown) { 402 printk(KERN_ALERT 403 "BUG: Bad page map: %lu messages suppressed\n", 404 nr_unshown); 405 nr_unshown = 0; 406 } 407 nr_shown = 0; 408 } 409 if (nr_shown++ == 0) 410 resume = jiffies + 60 * HZ; 411 412 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL; 413 index = linear_page_index(vma, addr); 414 415 printk(KERN_ALERT 416 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n", 417 current->comm, 418 (long long)pte_val(pte), (long long)pmd_val(*pmd)); 419 if (page) { 420 printk(KERN_ALERT 421 "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n", 422 page, (void *)page->flags, page_count(page), 423 page_mapcount(page), page->mapping, page->index); 424 } 425 printk(KERN_ALERT 426 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n", 427 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index); 428 /* 429 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y 430 */ 431 if (vma->vm_ops) 432 print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n", 433 (unsigned long)vma->vm_ops->fault); 434 if (vma->vm_file && vma->vm_file->f_op) 435 print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n", 436 (unsigned long)vma->vm_file->f_op->mmap); 437 dump_stack(); 438 add_taint(TAINT_BAD_PAGE); 439} 440 441static inline int is_cow_mapping(unsigned int flags) 442{ 443 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE; 444} 445 446/* 447 * vm_normal_page -- This function gets the "struct page" associated with a pte. 448 * 449 * "Special" mappings do not wish to be associated with a "struct page" (either 450 * it doesn't exist, or it exists but they don't want to touch it). In this 451 * case, NULL is returned here. "Normal" mappings do have a struct page. 452 * 453 * There are 2 broad cases. Firstly, an architecture may define a pte_special() 454 * pte bit, in which case this function is trivial. Secondly, an architecture 455 * may not have a spare pte bit, which requires a more complicated scheme, 456 * described below. 457 * 458 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a 459 * special mapping (even if there are underlying and valid "struct pages"). 460 * COWed pages of a VM_PFNMAP are always normal. 461 * 462 * The way we recognize COWed pages within VM_PFNMAP mappings is through the 463 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit 464 * set, and the vm_pgoff will point to the first PFN mapped: thus every special 465 * mapping will always honor the rule 466 * 467 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT) 468 * 469 * And for normal mappings this is false. 470 * 471 * This restricts such mappings to be a linear translation from virtual address 472 * to pfn. To get around this restriction, we allow arbitrary mappings so long 473 * as the vma is not a COW mapping; in that case, we know that all ptes are 474 * special (because none can have been COWed). 475 * 476 * 477 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP. 478 * 479 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct 480 * page" backing, however the difference is that _all_ pages with a struct 481 * page (that is, those where pfn_valid is true) are refcounted and considered 482 * normal pages by the VM. The disadvantage is that pages are refcounted 483 * (which can be slower and simply not an option for some PFNMAP users). The 484 * advantage is that we don't have to follow the strict linearity rule of 485 * PFNMAP mappings in order to support COWable mappings. 486 * 487 */ 488#ifdef __HAVE_ARCH_PTE_SPECIAL 489# define HAVE_PTE_SPECIAL 1 490#else 491# define HAVE_PTE_SPECIAL 0 492#endif 493struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr, 494 pte_t pte) 495{ 496 unsigned long pfn = pte_pfn(pte); 497 498 if (HAVE_PTE_SPECIAL) { 499 if (likely(!pte_special(pte))) 500 goto check_pfn; 501 if (!(vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))) 502 print_bad_pte(vma, addr, pte, NULL); 503 return NULL; 504 } 505 506 /* !HAVE_PTE_SPECIAL case follows: */ 507 508 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) { 509 if (vma->vm_flags & VM_MIXEDMAP) { 510 if (!pfn_valid(pfn)) 511 return NULL; 512 goto out; 513 } else { 514 unsigned long off; 515 off = (addr - vma->vm_start) >> PAGE_SHIFT; 516 if (pfn == vma->vm_pgoff + off) 517 return NULL; 518 if (!is_cow_mapping(vma->vm_flags)) 519 return NULL; 520 } 521 } 522 523check_pfn: 524 if (unlikely(pfn > highest_memmap_pfn)) { 525 print_bad_pte(vma, addr, pte, NULL); 526 return NULL; 527 } 528 529 /* 530 * NOTE! We still have PageReserved() pages in the page tables. 531 * eg. VDSO mappings can cause them to exist. 532 */ 533out: 534 return pfn_to_page(pfn); 535} 536 537/* 538 * copy one vm_area from one task to the other. Assumes the page tables 539 * already present in the new task to be cleared in the whole range 540 * covered by this vma. 541 */ 542 543static inline void 544copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm, 545 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma, 546 unsigned long addr, int *rss) 547{ 548 unsigned long vm_flags = vma->vm_flags; 549 pte_t pte = *src_pte; 550 struct page *page; 551 552 /* pte contains position in swap or file, so copy. */ 553 if (unlikely(!pte_present(pte))) { 554 if (!pte_file(pte)) { 555 swp_entry_t entry = pte_to_swp_entry(pte); 556 557 swap_duplicate(entry); 558 /* make sure dst_mm is on swapoff's mmlist. */ 559 if (unlikely(list_empty(&dst_mm->mmlist))) { 560 spin_lock(&mmlist_lock); 561 if (list_empty(&dst_mm->mmlist)) 562 list_add(&dst_mm->mmlist, 563 &src_mm->mmlist); 564 spin_unlock(&mmlist_lock); 565 } 566 if (is_write_migration_entry(entry) && 567 is_cow_mapping(vm_flags)) { 568 /* 569 * COW mappings require pages in both parent 570 * and child to be set to read. 571 */ 572 make_migration_entry_read(&entry); 573 pte = swp_entry_to_pte(entry); 574 set_pte_at(src_mm, addr, src_pte, pte); 575 } 576 } 577 goto out_set_pte; 578 } 579 580 /* 581 * If it's a COW mapping, write protect it both 582 * in the parent and the child 583 */ 584 if (is_cow_mapping(vm_flags)) { 585 ptep_set_wrprotect(src_mm, addr, src_pte); 586 pte = pte_wrprotect(pte); 587 } 588 589 /* 590 * If it's a shared mapping, mark it clean in 591 * the child 592 */ 593 if (vm_flags & VM_SHARED) 594 pte = pte_mkclean(pte); 595 pte = pte_mkold(pte); 596 597 page = vm_normal_page(vma, addr, pte); 598 if (page) { 599 get_page(page); 600 page_dup_rmap(page, vma, addr); 601 rss[!!PageAnon(page)]++; 602 } 603 604out_set_pte: 605 set_pte_at(dst_mm, addr, dst_pte, pte); 606} 607 608static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 609 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma, 610 unsigned long addr, unsigned long end) 611{ 612 pte_t *src_pte, *dst_pte; 613 spinlock_t *src_ptl, *dst_ptl; 614 int progress = 0; 615 int rss[2]; 616 617again: 618 rss[1] = rss[0] = 0; 619 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl); 620 if (!dst_pte) 621 return -ENOMEM; 622 src_pte = pte_offset_map_nested(src_pmd, addr); 623 src_ptl = pte_lockptr(src_mm, src_pmd); 624 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING); 625 arch_enter_lazy_mmu_mode(); 626 627 do { 628 /* 629 * We are holding two locks at this point - either of them 630 * could generate latencies in another task on another CPU. 631 */ 632 if (progress >= 32) { 633 progress = 0; 634 if (need_resched() || 635 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl)) 636 break; 637 } 638 if (pte_none(*src_pte)) { 639 progress++; 640 continue; 641 } 642 copy_one_pte(dst_mm, src_mm, dst_pte, src_pte, vma, addr, rss); 643 progress += 8; 644 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end); 645 646 arch_leave_lazy_mmu_mode(); 647 spin_unlock(src_ptl); 648 pte_unmap_nested(src_pte - 1); 649 add_mm_rss(dst_mm, rss[0], rss[1]); 650 pte_unmap_unlock(dst_pte - 1, dst_ptl); 651 cond_resched(); 652 if (addr != end) 653 goto again; 654 return 0; 655} 656 657static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 658 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma, 659 unsigned long addr, unsigned long end) 660{ 661 pmd_t *src_pmd, *dst_pmd; 662 unsigned long next; 663 664 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr); 665 if (!dst_pmd) 666 return -ENOMEM; 667 src_pmd = pmd_offset(src_pud, addr); 668 do { 669 next = pmd_addr_end(addr, end); 670 if (pmd_none_or_clear_bad(src_pmd)) 671 continue; 672 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd, 673 vma, addr, next)) 674 return -ENOMEM; 675 } while (dst_pmd++, src_pmd++, addr = next, addr != end); 676 return 0; 677} 678 679static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 680 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma, 681 unsigned long addr, unsigned long end) 682{ 683 pud_t *src_pud, *dst_pud; 684 unsigned long next; 685 686 dst_pud = pud_alloc(dst_mm, dst_pgd, addr); 687 if (!dst_pud) 688 return -ENOMEM; 689 src_pud = pud_offset(src_pgd, addr); 690 do { 691 next = pud_addr_end(addr, end); 692 if (pud_none_or_clear_bad(src_pud)) 693 continue; 694 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud, 695 vma, addr, next)) 696 return -ENOMEM; 697 } while (dst_pud++, src_pud++, addr = next, addr != end); 698 return 0; 699} 700 701int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 702 struct vm_area_struct *vma) 703{ 704 pgd_t *src_pgd, *dst_pgd; 705 unsigned long next; 706 unsigned long addr = vma->vm_start; 707 unsigned long end = vma->vm_end; 708 int ret; 709 710 /* 711 * Don't copy ptes where a page fault will fill them correctly. 712 * Fork becomes much lighter when there are big shared or private 713 * readonly mappings. The tradeoff is that copy_page_range is more 714 * efficient than faulting. 715 */ 716 if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) { 717 if (!vma->anon_vma) 718 return 0; 719 } 720 721 if (is_vm_hugetlb_page(vma)) 722 return copy_hugetlb_page_range(dst_mm, src_mm, vma); 723 724 if (unlikely(is_pfn_mapping(vma))) { 725 /* 726 * We do not free on error cases below as remove_vma 727 * gets called on error from higher level routine 728 */ 729 ret = track_pfn_vma_copy(vma); 730 if (ret) 731 return ret; 732 } 733 734 /* 735 * We need to invalidate the secondary MMU mappings only when 736 * there could be a permission downgrade on the ptes of the 737 * parent mm. And a permission downgrade will only happen if 738 * is_cow_mapping() returns true. 739 */ 740 if (is_cow_mapping(vma->vm_flags)) 741 mmu_notifier_invalidate_range_start(src_mm, addr, end); 742 743 ret = 0; 744 dst_pgd = pgd_offset(dst_mm, addr); 745 src_pgd = pgd_offset(src_mm, addr); 746 do { 747 next = pgd_addr_end(addr, end); 748 if (pgd_none_or_clear_bad(src_pgd)) 749 continue; 750 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd, 751 vma, addr, next))) { 752 ret = -ENOMEM; 753 break; 754 } 755 } while (dst_pgd++, src_pgd++, addr = next, addr != end); 756 757 if (is_cow_mapping(vma->vm_flags)) 758 mmu_notifier_invalidate_range_end(src_mm, 759 vma->vm_start, end); 760 return ret; 761} 762 763static unsigned long zap_pte_range(struct mmu_gather *tlb, 764 struct vm_area_struct *vma, pmd_t *pmd, 765 unsigned long addr, unsigned long end, 766 long *zap_work, struct zap_details *details) 767{ 768 struct mm_struct *mm = tlb->mm; 769 pte_t *pte; 770 spinlock_t *ptl; 771 int file_rss = 0; 772 int anon_rss = 0; 773 774 pte = pte_offset_map_lock(mm, pmd, addr, &ptl); 775 arch_enter_lazy_mmu_mode(); 776 do { 777 pte_t ptent = *pte; 778 if (pte_none(ptent)) { 779 (*zap_work)--; 780 continue; 781 } 782 783 (*zap_work) -= PAGE_SIZE; 784 785 if (pte_present(ptent)) { 786 struct page *page; 787 788 page = vm_normal_page(vma, addr, ptent); 789 if (unlikely(details) && page) { 790 /* 791 * unmap_shared_mapping_pages() wants to 792 * invalidate cache without truncating: 793 * unmap shared but keep private pages. 794 */ 795 if (details->check_mapping && 796 details->check_mapping != page->mapping) 797 continue; 798 /* 799 * Each page->index must be checked when 800 * invalidating or truncating nonlinear. 801 */ 802 if (details->nonlinear_vma && 803 (page->index < details->first_index || 804 page->index > details->last_index)) 805 continue; 806 } 807 ptent = ptep_get_and_clear_full(mm, addr, pte, 808 tlb->fullmm); 809 tlb_remove_tlb_entry(tlb, pte, addr); 810 if (unlikely(!page)) 811 continue; 812 if (unlikely(details) && details->nonlinear_vma 813 && linear_page_index(details->nonlinear_vma, 814 addr) != page->index) 815 set_pte_at(mm, addr, pte, 816 pgoff_to_pte(page->index)); 817 if (PageAnon(page)) 818 anon_rss--; 819 else { 820 if (pte_dirty(ptent)) 821 set_page_dirty(page); 822 if (pte_young(ptent) && 823 likely(!VM_SequentialReadHint(vma))) 824 mark_page_accessed(page); 825 file_rss--; 826 } 827 page_remove_rmap(page); 828 if (unlikely(page_mapcount(page) < 0)) 829 print_bad_pte(vma, addr, ptent, page); 830 tlb_remove_page(tlb, page); 831 continue; 832 } 833 /* 834 * If details->check_mapping, we leave swap entries; 835 * if details->nonlinear_vma, we leave file entries. 836 */ 837 if (unlikely(details)) 838 continue; 839 if (pte_file(ptent)) { 840 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) 841 print_bad_pte(vma, addr, ptent, NULL); 842 } else if 843 (unlikely(!free_swap_and_cache(pte_to_swp_entry(ptent)))) 844 print_bad_pte(vma, addr, ptent, NULL); 845 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); 846 } while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0)); 847 848 add_mm_rss(mm, file_rss, anon_rss); 849 arch_leave_lazy_mmu_mode(); 850 pte_unmap_unlock(pte - 1, ptl); 851 852 return addr; 853} 854 855static inline unsigned long zap_pmd_range(struct mmu_gather *tlb, 856 struct vm_area_struct *vma, pud_t *pud, 857 unsigned long addr, unsigned long end, 858 long *zap_work, struct zap_details *details) 859{ 860 pmd_t *pmd; 861 unsigned long next; 862 863 pmd = pmd_offset(pud, addr); 864 do { 865 next = pmd_addr_end(addr, end); 866 if (pmd_none_or_clear_bad(pmd)) { 867 (*zap_work)--; 868 continue; 869 } 870 next = zap_pte_range(tlb, vma, pmd, addr, next, 871 zap_work, details); 872 } while (pmd++, addr = next, (addr != end && *zap_work > 0)); 873 874 return addr; 875} 876 877static inline unsigned long zap_pud_range(struct mmu_gather *tlb, 878 struct vm_area_struct *vma, pgd_t *pgd, 879 unsigned long addr, unsigned long end, 880 long *zap_work, struct zap_details *details) 881{ 882 pud_t *pud; 883 unsigned long next; 884 885 pud = pud_offset(pgd, addr); 886 do { 887 next = pud_addr_end(addr, end); 888 if (pud_none_or_clear_bad(pud)) { 889 (*zap_work)--; 890 continue; 891 } 892 next = zap_pmd_range(tlb, vma, pud, addr, next, 893 zap_work, details); 894 } while (pud++, addr = next, (addr != end && *zap_work > 0)); 895 896 return addr; 897} 898 899static unsigned long unmap_page_range(struct mmu_gather *tlb, 900 struct vm_area_struct *vma, 901 unsigned long addr, unsigned long end, 902 long *zap_work, struct zap_details *details) 903{ 904 pgd_t *pgd; 905 unsigned long next; 906 907 if (details && !details->check_mapping && !details->nonlinear_vma) 908 details = NULL; 909 910 BUG_ON(addr >= end); 911 tlb_start_vma(tlb, vma); 912 pgd = pgd_offset(vma->vm_mm, addr); 913 do { 914 next = pgd_addr_end(addr, end); 915 if (pgd_none_or_clear_bad(pgd)) { 916 (*zap_work)--; 917 continue; 918 } 919 next = zap_pud_range(tlb, vma, pgd, addr, next, 920 zap_work, details); 921 } while (pgd++, addr = next, (addr != end && *zap_work > 0)); 922 tlb_end_vma(tlb, vma); 923 924 return addr; 925} 926 927#ifdef CONFIG_PREEMPT 928# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE) 929#else 930/* No preempt: go for improved straight-line efficiency */ 931# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE) 932#endif 933 934/** 935 * unmap_vmas - unmap a range of memory covered by a list of vma's 936 * @tlbp: address of the caller's struct mmu_gather 937 * @vma: the starting vma 938 * @start_addr: virtual address at which to start unmapping 939 * @end_addr: virtual address at which to end unmapping 940 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here 941 * @details: details of nonlinear truncation or shared cache invalidation 942 * 943 * Returns the end address of the unmapping (restart addr if interrupted). 944 * 945 * Unmap all pages in the vma list. 946 * 947 * We aim to not hold locks for too long (for scheduling latency reasons). 948 * So zap pages in ZAP_BLOCK_SIZE bytecounts. This means we need to 949 * return the ending mmu_gather to the caller. 950 * 951 * Only addresses between `start' and `end' will be unmapped. 952 * 953 * The VMA list must be sorted in ascending virtual address order. 954 * 955 * unmap_vmas() assumes that the caller will flush the whole unmapped address 956 * range after unmap_vmas() returns. So the only responsibility here is to 957 * ensure that any thus-far unmapped pages are flushed before unmap_vmas() 958 * drops the lock and schedules. 959 */ 960unsigned long unmap_vmas(struct mmu_gather **tlbp, 961 struct vm_area_struct *vma, unsigned long start_addr, 962 unsigned long end_addr, unsigned long *nr_accounted, 963 struct zap_details *details) 964{ 965 long zap_work = ZAP_BLOCK_SIZE; 966 unsigned long tlb_start = 0; /* For tlb_finish_mmu */ 967 int tlb_start_valid = 0; 968 unsigned long start = start_addr; 969 spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL; 970 int fullmm = (*tlbp)->fullmm; 971 struct mm_struct *mm = vma->vm_mm; 972 973 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr); 974 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) { 975 unsigned long end; 976 977 start = max(vma->vm_start, start_addr); 978 if (start >= vma->vm_end) 979 continue; 980 end = min(vma->vm_end, end_addr); 981 if (end <= vma->vm_start) 982 continue; 983 984 if (vma->vm_flags & VM_ACCOUNT) 985 *nr_accounted += (end - start) >> PAGE_SHIFT; 986 987 if (unlikely(is_pfn_mapping(vma))) 988 untrack_pfn_vma(vma, 0, 0); 989 990 while (start != end) { 991 if (!tlb_start_valid) { 992 tlb_start = start; 993 tlb_start_valid = 1; 994 } 995 996 if (unlikely(is_vm_hugetlb_page(vma))) { 997 /* 998 * It is undesirable to test vma->vm_file as it 999 * should be non-null for valid hugetlb area. 1000 * However, vm_file will be NULL in the error 1001 * cleanup path of do_mmap_pgoff. When 1002 * hugetlbfs ->mmap method fails, 1003 * do_mmap_pgoff() nullifies vma->vm_file 1004 * before calling this function to clean up. 1005 * Since no pte has actually been setup, it is 1006 * safe to do nothing in this case. 1007 */ 1008 if (vma->vm_file) { 1009 unmap_hugepage_range(vma, start, end, NULL); 1010 zap_work -= (end - start) / 1011 pages_per_huge_page(hstate_vma(vma)); 1012 } 1013 1014 start = end; 1015 } else 1016 start = unmap_page_range(*tlbp, vma, 1017 start, end, &zap_work, details); 1018 1019 if (zap_work > 0) { 1020 BUG_ON(start != end); 1021 break; 1022 } 1023 1024 tlb_finish_mmu(*tlbp, tlb_start, start); 1025 1026 if (need_resched() || 1027 (i_mmap_lock && spin_needbreak(i_mmap_lock))) { 1028 if (i_mmap_lock) { 1029 *tlbp = NULL; 1030 goto out; 1031 } 1032 cond_resched(); 1033 } 1034 1035 *tlbp = tlb_gather_mmu(vma->vm_mm, fullmm); 1036 tlb_start_valid = 0; 1037 zap_work = ZAP_BLOCK_SIZE; 1038 } 1039 } 1040out: 1041 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr); 1042 return start; /* which is now the end (or restart) address */ 1043} 1044 1045/** 1046 * zap_page_range - remove user pages in a given range 1047 * @vma: vm_area_struct holding the applicable pages 1048 * @address: starting address of pages to zap 1049 * @size: number of bytes to zap 1050 * @details: details of nonlinear truncation or shared cache invalidation 1051 */ 1052unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address, 1053 unsigned long size, struct zap_details *details) 1054{ 1055 struct mm_struct *mm = vma->vm_mm; 1056 struct mmu_gather *tlb; 1057 unsigned long end = address + size; 1058 unsigned long nr_accounted = 0; 1059 1060 lru_add_drain(); 1061 tlb = tlb_gather_mmu(mm, 0); 1062 update_hiwater_rss(mm); 1063 end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details); 1064 if (tlb) 1065 tlb_finish_mmu(tlb, address, end); 1066 return end; 1067} 1068 1069/** 1070 * zap_vma_ptes - remove ptes mapping the vma 1071 * @vma: vm_area_struct holding ptes to be zapped 1072 * @address: starting address of pages to zap 1073 * @size: number of bytes to zap 1074 * 1075 * This function only unmaps ptes assigned to VM_PFNMAP vmas. 1076 * 1077 * The entire address range must be fully contained within the vma. 1078 * 1079 * Returns 0 if successful. 1080 */ 1081int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address, 1082 unsigned long size) 1083{ 1084 if (address < vma->vm_start || address + size > vma->vm_end || 1085 !(vma->vm_flags & VM_PFNMAP)) 1086 return -1; 1087 zap_page_range(vma, address, size, NULL); 1088 return 0; 1089} 1090EXPORT_SYMBOL_GPL(zap_vma_ptes); 1091 1092/* 1093 * Do a quick page-table lookup for a single page. 1094 */ 1095struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1096 unsigned int flags) 1097{ 1098 pgd_t *pgd; 1099 pud_t *pud; 1100 pmd_t *pmd; 1101 pte_t *ptep, pte; 1102 spinlock_t *ptl; 1103 struct page *page; 1104 struct mm_struct *mm = vma->vm_mm; 1105 1106 page = follow_huge_addr(mm, address, flags & FOLL_WRITE); 1107 if (!IS_ERR(page)) { 1108 BUG_ON(flags & FOLL_GET); 1109 goto out; 1110 } 1111 1112 page = NULL; 1113 pgd = pgd_offset(mm, address); 1114 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 1115 goto no_page_table; 1116 1117 pud = pud_offset(pgd, address); 1118 if (pud_none(*pud)) 1119 goto no_page_table; 1120 if (pud_huge(*pud)) { 1121 BUG_ON(flags & FOLL_GET); 1122 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE); 1123 goto out; 1124 } 1125 if (unlikely(pud_bad(*pud))) 1126 goto no_page_table; 1127 1128 pmd = pmd_offset(pud, address); 1129 if (pmd_none(*pmd)) 1130 goto no_page_table; 1131 if (pmd_huge(*pmd)) { 1132 BUG_ON(flags & FOLL_GET); 1133 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE); 1134 goto out; 1135 } 1136 if (unlikely(pmd_bad(*pmd))) 1137 goto no_page_table; 1138 1139 ptep = pte_offset_map_lock(mm, pmd, address, &ptl); 1140 1141 pte = *ptep; 1142 if (!pte_present(pte)) 1143 goto no_page; 1144 if ((flags & FOLL_WRITE) && !pte_write(pte)) 1145 goto unlock; 1146 page = vm_normal_page(vma, address, pte); 1147 if (unlikely(!page)) 1148 goto bad_page; 1149 1150 if (flags & FOLL_GET) 1151 get_page(page); 1152 if (flags & FOLL_TOUCH) { 1153 if ((flags & FOLL_WRITE) && 1154 !pte_dirty(pte) && !PageDirty(page)) 1155 set_page_dirty(page); 1156 /* 1157 * pte_mkyoung() would be more correct here, but atomic care 1158 * is needed to avoid losing the dirty bit: it is easier to use 1159 * mark_page_accessed(). 1160 */ 1161 mark_page_accessed(page); 1162 } 1163unlock: 1164 pte_unmap_unlock(ptep, ptl); 1165out: 1166 return page; 1167 1168bad_page: 1169 pte_unmap_unlock(ptep, ptl); 1170 return ERR_PTR(-EFAULT); 1171 1172no_page: 1173 pte_unmap_unlock(ptep, ptl); 1174 if (!pte_none(pte)) 1175 return page; 1176 /* Fall through to ZERO_PAGE handling */ 1177no_page_table: 1178 /* 1179 * When core dumping an enormous anonymous area that nobody 1180 * has touched so far, we don't want to allocate page tables. 1181 */ 1182 if (flags & FOLL_ANON) { 1183 page = ZERO_PAGE(0); 1184 if (flags & FOLL_GET) 1185 get_page(page); 1186 BUG_ON(flags & FOLL_WRITE); 1187 } 1188 return page; 1189} 1190 1191/* Can we do the FOLL_ANON optimization? */ 1192static inline int use_zero_page(struct vm_area_struct *vma) 1193{ 1194 /* 1195 * We don't want to optimize FOLL_ANON for make_pages_present() 1196 * when it tries to page in a VM_LOCKED region. As to VM_SHARED, 1197 * we want to get the page from the page tables to make sure 1198 * that we serialize and update with any other user of that 1199 * mapping. 1200 */ 1201 if (vma->vm_flags & (VM_LOCKED | VM_SHARED)) 1202 return 0; 1203 /* 1204 * And if we have a fault routine, it's not an anonymous region. 1205 */ 1206 return !vma->vm_ops || !vma->vm_ops->fault; 1207} 1208 1209 1210 1211int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1212 unsigned long start, int nr_pages, int flags, 1213 struct page **pages, struct vm_area_struct **vmas) 1214{ 1215 int i; 1216 unsigned int vm_flags = 0; 1217 int write = !!(flags & GUP_FLAGS_WRITE); 1218 int force = !!(flags & GUP_FLAGS_FORCE); 1219 int ignore = !!(flags & GUP_FLAGS_IGNORE_VMA_PERMISSIONS); 1220 int ignore_sigkill = !!(flags & GUP_FLAGS_IGNORE_SIGKILL); 1221 1222 if (nr_pages <= 0) 1223 return 0; 1224 /* 1225 * Require read or write permissions. 1226 * If 'force' is set, we only require the "MAY" flags. 1227 */ 1228 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 1229 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 1230 i = 0; 1231 1232 do { 1233 struct vm_area_struct *vma; 1234 unsigned int foll_flags; 1235 1236 vma = find_extend_vma(mm, start); 1237 if (!vma && in_gate_area(tsk, start)) { 1238 unsigned long pg = start & PAGE_MASK; 1239 struct vm_area_struct *gate_vma = get_gate_vma(tsk); 1240 pgd_t *pgd; 1241 pud_t *pud; 1242 pmd_t *pmd; 1243 pte_t *pte; 1244 1245 /* user gate pages are read-only */ 1246 if (!ignore && write) 1247 return i ? : -EFAULT; 1248 if (pg > TASK_SIZE) 1249 pgd = pgd_offset_k(pg); 1250 else 1251 pgd = pgd_offset_gate(mm, pg); 1252 BUG_ON(pgd_none(*pgd)); 1253 pud = pud_offset(pgd, pg); 1254 BUG_ON(pud_none(*pud)); 1255 pmd = pmd_offset(pud, pg); 1256 if (pmd_none(*pmd)) 1257 return i ? : -EFAULT; 1258 pte = pte_offset_map(pmd, pg); 1259 if (pte_none(*pte)) { 1260 pte_unmap(pte); 1261 return i ? : -EFAULT; 1262 } 1263 if (pages) { 1264 struct page *page = vm_normal_page(gate_vma, start, *pte); 1265 pages[i] = page; 1266 if (page) 1267 get_page(page); 1268 } 1269 pte_unmap(pte); 1270 if (vmas) 1271 vmas[i] = gate_vma; 1272 i++; 1273 start += PAGE_SIZE; 1274 nr_pages--; 1275 continue; 1276 } 1277 1278 if (!vma || 1279 (vma->vm_flags & (VM_IO | VM_PFNMAP)) || 1280 (!ignore && !(vm_flags & vma->vm_flags))) 1281 return i ? : -EFAULT; 1282 1283 if (is_vm_hugetlb_page(vma)) { 1284 i = follow_hugetlb_page(mm, vma, pages, vmas, 1285 &start, &nr_pages, i, write); 1286 continue; 1287 } 1288 1289 foll_flags = FOLL_TOUCH; 1290 if (pages) 1291 foll_flags |= FOLL_GET; 1292 if (!write && use_zero_page(vma)) 1293 foll_flags |= FOLL_ANON; 1294 1295 do { 1296 struct page *page; 1297 1298 /* 1299 * If we have a pending SIGKILL, don't keep faulting 1300 * pages and potentially allocating memory, unless 1301 * current is handling munlock--e.g., on exit. In 1302 * that case, we are not allocating memory. Rather, 1303 * we're only unlocking already resident/mapped pages. 1304 */ 1305 if (unlikely(!ignore_sigkill && 1306 fatal_signal_pending(current))) 1307 return i ? i : -ERESTARTSYS; 1308 1309 if (write) 1310 foll_flags |= FOLL_WRITE; 1311 1312 cond_resched(); 1313 while (!(page = follow_page(vma, start, foll_flags))) { 1314 int ret; 1315 1316 ret = handle_mm_fault(mm, vma, start, 1317 (foll_flags & FOLL_WRITE) ? 1318 FAULT_FLAG_WRITE : 0); 1319 1320 if (ret & VM_FAULT_ERROR) { 1321 if (ret & VM_FAULT_OOM) 1322 return i ? i : -ENOMEM; 1323 else if (ret & VM_FAULT_SIGBUS) 1324 return i ? i : -EFAULT; 1325 BUG(); 1326 } 1327 if (ret & VM_FAULT_MAJOR) 1328 tsk->maj_flt++; 1329 else 1330 tsk->min_flt++; 1331 1332 /* 1333 * The VM_FAULT_WRITE bit tells us that 1334 * do_wp_page has broken COW when necessary, 1335 * even if maybe_mkwrite decided not to set 1336 * pte_write. We can thus safely do subsequent 1337 * page lookups as if they were reads. But only 1338 * do so when looping for pte_write is futile: 1339 * in some cases userspace may also be wanting 1340 * to write to the gotten user page, which a 1341 * read fault here might prevent (a readonly 1342 * page might get reCOWed by userspace write). 1343 */ 1344 if ((ret & VM_FAULT_WRITE) && 1345 !(vma->vm_flags & VM_WRITE)) 1346 foll_flags &= ~FOLL_WRITE; 1347 1348 cond_resched(); 1349 } 1350 if (IS_ERR(page)) 1351 return i ? i : PTR_ERR(page); 1352 if (pages) { 1353 pages[i] = page; 1354 1355 flush_anon_page(vma, page, start); 1356 flush_dcache_page(page); 1357 } 1358 if (vmas) 1359 vmas[i] = vma; 1360 i++; 1361 start += PAGE_SIZE; 1362 nr_pages--; 1363 } while (nr_pages && start < vma->vm_end); 1364 } while (nr_pages); 1365 return i; 1366} 1367 1368/** 1369 * get_user_pages() - pin user pages in memory 1370 * @tsk: task_struct of target task 1371 * @mm: mm_struct of target mm 1372 * @start: starting user address 1373 * @nr_pages: number of pages from start to pin 1374 * @write: whether pages will be written to by the caller 1375 * @force: whether to force write access even if user mapping is 1376 * readonly. This will result in the page being COWed even 1377 * in MAP_SHARED mappings. You do not want this. 1378 * @pages: array that receives pointers to the pages pinned. 1379 * Should be at least nr_pages long. Or NULL, if caller 1380 * only intends to ensure the pages are faulted in. 1381 * @vmas: array of pointers to vmas corresponding to each page. 1382 * Or NULL if the caller does not require them. 1383 * 1384 * Returns number of pages pinned. This may be fewer than the number 1385 * requested. If nr_pages is 0 or negative, returns 0. If no pages 1386 * were pinned, returns -errno. Each page returned must be released 1387 * with a put_page() call when it is finished with. vmas will only 1388 * remain valid while mmap_sem is held. 1389 * 1390 * Must be called with mmap_sem held for read or write. 1391 * 1392 * get_user_pages walks a process's page tables and takes a reference to 1393 * each struct page that each user address corresponds to at a given 1394 * instant. That is, it takes the page that would be accessed if a user 1395 * thread accesses the given user virtual address at that instant. 1396 * 1397 * This does not guarantee that the page exists in the user mappings when 1398 * get_user_pages returns, and there may even be a completely different 1399 * page there in some cases (eg. if mmapped pagecache has been invalidated 1400 * and subsequently re faulted). However it does guarantee that the page 1401 * won't be freed completely. And mostly callers simply care that the page 1402 * contains data that was valid *at some point in time*. Typically, an IO 1403 * or similar operation cannot guarantee anything stronger anyway because 1404 * locks can't be held over the syscall boundary. 1405 * 1406 * If write=0, the page must not be written to. If the page is written to, 1407 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called 1408 * after the page is finished with, and before put_page is called. 1409 * 1410 * get_user_pages is typically used for fewer-copy IO operations, to get a 1411 * handle on the memory by some means other than accesses via the user virtual 1412 * addresses. The pages may be submitted for DMA to devices or accessed via 1413 * their kernel linear mapping (via the kmap APIs). Care should be taken to 1414 * use the correct cache flushing APIs. 1415 * 1416 * See also get_user_pages_fast, for performance critical applications. 1417 */ 1418int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 1419 unsigned long start, int nr_pages, int write, int force, 1420 struct page **pages, struct vm_area_struct **vmas) 1421{ 1422 int flags = 0; 1423 1424 if (write) 1425 flags |= GUP_FLAGS_WRITE; 1426 if (force) 1427 flags |= GUP_FLAGS_FORCE; 1428 1429 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas); 1430} 1431 1432EXPORT_SYMBOL(get_user_pages); 1433 1434pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr, 1435 spinlock_t **ptl) 1436{ 1437 pgd_t * pgd = pgd_offset(mm, addr); 1438 pud_t * pud = pud_alloc(mm, pgd, addr); 1439 if (pud) { 1440 pmd_t * pmd = pmd_alloc(mm, pud, addr); 1441 if (pmd) 1442 return pte_alloc_map_lock(mm, pmd, addr, ptl); 1443 } 1444 return NULL; 1445} 1446 1447/* 1448 * This is the old fallback for page remapping. 1449 * 1450 * For historical reasons, it only allows reserved pages. Only 1451 * old drivers should use this, and they needed to mark their 1452 * pages reserved for the old functions anyway. 1453 */ 1454static int insert_page(struct vm_area_struct *vma, unsigned long addr, 1455 struct page *page, pgprot_t prot) 1456{ 1457 struct mm_struct *mm = vma->vm_mm; 1458 int retval; 1459 pte_t *pte; 1460 spinlock_t *ptl; 1461 1462 retval = -EINVAL; 1463 if (PageAnon(page)) 1464 goto out; 1465 retval = -ENOMEM; 1466 flush_dcache_page(page); 1467 pte = get_locked_pte(mm, addr, &ptl); 1468 if (!pte) 1469 goto out; 1470 retval = -EBUSY; 1471 if (!pte_none(*pte)) 1472 goto out_unlock; 1473 1474 /* Ok, finally just insert the thing.. */ 1475 get_page(page); 1476 inc_mm_counter(mm, file_rss); 1477 page_add_file_rmap(page); 1478 set_pte_at(mm, addr, pte, mk_pte(page, prot)); 1479 1480 retval = 0; 1481 pte_unmap_unlock(pte, ptl); 1482 return retval; 1483out_unlock: 1484 pte_unmap_unlock(pte, ptl); 1485out: 1486 return retval; 1487} 1488 1489/** 1490 * vm_insert_page - insert single page into user vma 1491 * @vma: user vma to map to 1492 * @addr: target user address of this page 1493 * @page: source kernel page 1494 * 1495 * This allows drivers to insert individual pages they've allocated 1496 * into a user vma. 1497 * 1498 * The page has to be a nice clean _individual_ kernel allocation. 1499 * If you allocate a compound page, you need to have marked it as 1500 * such (__GFP_COMP), or manually just split the page up yourself 1501 * (see split_page()). 1502 * 1503 * NOTE! Traditionally this was done with "remap_pfn_range()" which 1504 * took an arbitrary page protection parameter. This doesn't allow 1505 * that. Your vma protection will have to be set up correctly, which 1506 * means that if you want a shared writable mapping, you'd better 1507 * ask for a shared writable mapping! 1508 * 1509 * The page does not need to be reserved. 1510 */ 1511int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 1512 struct page *page) 1513{ 1514 if (addr < vma->vm_start || addr >= vma->vm_end) 1515 return -EFAULT; 1516 if (!page_count(page)) 1517 return -EINVAL; 1518 vma->vm_flags |= VM_INSERTPAGE; 1519 return insert_page(vma, addr, page, vma->vm_page_prot); 1520} 1521EXPORT_SYMBOL(vm_insert_page); 1522 1523static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1524 unsigned long pfn, pgprot_t prot) 1525{ 1526 struct mm_struct *mm = vma->vm_mm; 1527 int retval; 1528 pte_t *pte, entry; 1529 spinlock_t *ptl; 1530 1531 retval = -ENOMEM; 1532 pte = get_locked_pte(mm, addr, &ptl); 1533 if (!pte) 1534 goto out; 1535 retval = -EBUSY; 1536 if (!pte_none(*pte)) 1537 goto out_unlock; 1538 1539 /* Ok, finally just insert the thing.. */ 1540 entry = pte_mkspecial(pfn_pte(pfn, prot)); 1541 set_pte_at(mm, addr, pte, entry); 1542 update_mmu_cache(vma, addr, entry); /* XXX: why not for insert_page? */ 1543 1544 retval = 0; 1545out_unlock: 1546 pte_unmap_unlock(pte, ptl); 1547out: 1548 return retval; 1549} 1550 1551/** 1552 * vm_insert_pfn - insert single pfn into user vma 1553 * @vma: user vma to map to 1554 * @addr: target user address of this page 1555 * @pfn: source kernel pfn 1556 * 1557 * Similar to vm_inert_page, this allows drivers to insert individual pages 1558 * they've allocated into a user vma. Same comments apply. 1559 * 1560 * This function should only be called from a vm_ops->fault handler, and 1561 * in that case the handler should return NULL. 1562 * 1563 * vma cannot be a COW mapping. 1564 * 1565 * As this is called only for pages that do not currently exist, we 1566 * do not need to flush old virtual caches or the TLB. 1567 */ 1568int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, 1569 unsigned long pfn) 1570{ 1571 int ret; 1572 pgprot_t pgprot = vma->vm_page_prot; 1573 /* 1574 * Technically, architectures with pte_special can avoid all these 1575 * restrictions (same for remap_pfn_range). However we would like 1576 * consistency in testing and feature parity among all, so we should 1577 * try to keep these invariants in place for everybody. 1578 */ 1579 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))); 1580 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) == 1581 (VM_PFNMAP|VM_MIXEDMAP)); 1582 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags)); 1583 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn)); 1584 1585 if (addr < vma->vm_start || addr >= vma->vm_end) 1586 return -EFAULT; 1587 if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE)) 1588 return -EINVAL; 1589 1590 ret = insert_pfn(vma, addr, pfn, pgprot); 1591 1592 if (ret) 1593 untrack_pfn_vma(vma, pfn, PAGE_SIZE); 1594 1595 return ret; 1596} 1597EXPORT_SYMBOL(vm_insert_pfn); 1598 1599int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, 1600 unsigned long pfn) 1601{ 1602 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP)); 1603 1604 if (addr < vma->vm_start || addr >= vma->vm_end) 1605 return -EFAULT; 1606 1607 /* 1608 * If we don't have pte special, then we have to use the pfn_valid() 1609 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must* 1610 * refcount the page if pfn_valid is true (hence insert_page rather 1611 * than insert_pfn). 1612 */ 1613 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) { 1614 struct page *page; 1615 1616 page = pfn_to_page(pfn); 1617 return insert_page(vma, addr, page, vma->vm_page_prot); 1618 } 1619 return insert_pfn(vma, addr, pfn, vma->vm_page_prot); 1620} 1621EXPORT_SYMBOL(vm_insert_mixed); 1622 1623/* 1624 * maps a range of physical memory into the requested pages. the old 1625 * mappings are removed. any references to nonexistent pages results 1626 * in null mappings (currently treated as "copy-on-access") 1627 */ 1628static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd, 1629 unsigned long addr, unsigned long end, 1630 unsigned long pfn, pgprot_t prot) 1631{ 1632 pte_t *pte; 1633 spinlock_t *ptl; 1634 1635 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl); 1636 if (!pte) 1637 return -ENOMEM; 1638 arch_enter_lazy_mmu_mode(); 1639 do { 1640 BUG_ON(!pte_none(*pte)); 1641 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot))); 1642 pfn++; 1643 } while (pte++, addr += PAGE_SIZE, addr != end); 1644 arch_leave_lazy_mmu_mode(); 1645 pte_unmap_unlock(pte - 1, ptl); 1646 return 0; 1647} 1648 1649static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud, 1650 unsigned long addr, unsigned long end, 1651 unsigned long pfn, pgprot_t prot) 1652{ 1653 pmd_t *pmd; 1654 unsigned long next; 1655 1656 pfn -= addr >> PAGE_SHIFT; 1657 pmd = pmd_alloc(mm, pud, addr); 1658 if (!pmd) 1659 return -ENOMEM; 1660 do { 1661 next = pmd_addr_end(addr, end); 1662 if (remap_pte_range(mm, pmd, addr, next, 1663 pfn + (addr >> PAGE_SHIFT), prot)) 1664 return -ENOMEM; 1665 } while (pmd++, addr = next, addr != end); 1666 return 0; 1667} 1668 1669static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd, 1670 unsigned long addr, unsigned long end, 1671 unsigned long pfn, pgprot_t prot) 1672{ 1673 pud_t *pud; 1674 unsigned long next; 1675 1676 pfn -= addr >> PAGE_SHIFT; 1677 pud = pud_alloc(mm, pgd, addr); 1678 if (!pud) 1679 return -ENOMEM; 1680 do { 1681 next = pud_addr_end(addr, end); 1682 if (remap_pmd_range(mm, pud, addr, next, 1683 pfn + (addr >> PAGE_SHIFT), prot)) 1684 return -ENOMEM; 1685 } while (pud++, addr = next, addr != end); 1686 return 0; 1687} 1688 1689/** 1690 * remap_pfn_range - remap kernel memory to userspace 1691 * @vma: user vma to map to 1692 * @addr: target user address to start at 1693 * @pfn: physical address of kernel memory 1694 * @size: size of map area 1695 * @prot: page protection flags for this mapping 1696 * 1697 * Note: this is only safe if the mm semaphore is held when called. 1698 */ 1699int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1700 unsigned long pfn, unsigned long size, pgprot_t prot) 1701{ 1702 pgd_t *pgd; 1703 unsigned long next; 1704 unsigned long end = addr + PAGE_ALIGN(size); 1705 struct mm_struct *mm = vma->vm_mm; 1706 int err; 1707 1708 /* 1709 * Physically remapped pages are special. Tell the 1710 * rest of the world about it: 1711 * VM_IO tells people not to look at these pages 1712 * (accesses can have side effects). 1713 * VM_RESERVED is specified all over the place, because 1714 * in 2.4 it kept swapout's vma scan off this vma; but 1715 * in 2.6 the LRU scan won't even find its pages, so this 1716 * flag means no more than count its pages in reserved_vm, 1717 * and omit it from core dump, even when VM_IO turned off. 1718 * VM_PFNMAP tells the core MM that the base pages are just 1719 * raw PFN mappings, and do not have a "struct page" associated 1720 * with them. 1721 * 1722 * There's a horrible special case to handle copy-on-write 1723 * behaviour that some programs depend on. We mark the "original" 1724 * un-COW'ed pages by matching them up with "vma->vm_pgoff". 1725 */ 1726 if (addr == vma->vm_start && end == vma->vm_end) { 1727 vma->vm_pgoff = pfn; 1728 vma->vm_flags |= VM_PFN_AT_MMAP; 1729 } else if (is_cow_mapping(vma->vm_flags)) 1730 return -EINVAL; 1731 1732 vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP; 1733 1734 err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size)); 1735 if (err) { 1736 /* 1737 * To indicate that track_pfn related cleanup is not 1738 * needed from higher level routine calling unmap_vmas 1739 */ 1740 vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP); 1741 vma->vm_flags &= ~VM_PFN_AT_MMAP; 1742 return -EINVAL; 1743 } 1744 1745 BUG_ON(addr >= end); 1746 pfn -= addr >> PAGE_SHIFT; 1747 pgd = pgd_offset(mm, addr); 1748 flush_cache_range(vma, addr, end); 1749 do { 1750 next = pgd_addr_end(addr, end); 1751 err = remap_pud_range(mm, pgd, addr, next, 1752 pfn + (addr >> PAGE_SHIFT), prot); 1753 if (err) 1754 break; 1755 } while (pgd++, addr = next, addr != end); 1756 1757 if (err) 1758 untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size)); 1759 1760 return err; 1761} 1762EXPORT_SYMBOL(remap_pfn_range); 1763 1764static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd, 1765 unsigned long addr, unsigned long end, 1766 pte_fn_t fn, void *data) 1767{ 1768 pte_t *pte; 1769 int err; 1770 pgtable_t token; 1771 spinlock_t *uninitialized_var(ptl); 1772 1773 pte = (mm == &init_mm) ? 1774 pte_alloc_kernel(pmd, addr) : 1775 pte_alloc_map_lock(mm, pmd, addr, &ptl); 1776 if (!pte) 1777 return -ENOMEM; 1778 1779 BUG_ON(pmd_huge(*pmd)); 1780 1781 arch_enter_lazy_mmu_mode(); 1782 1783 token = pmd_pgtable(*pmd); 1784 1785 do { 1786 err = fn(pte, token, addr, data); 1787 if (err) 1788 break; 1789 } while (pte++, addr += PAGE_SIZE, addr != end); 1790 1791 arch_leave_lazy_mmu_mode(); 1792 1793 if (mm != &init_mm) 1794 pte_unmap_unlock(pte-1, ptl); 1795 return err; 1796} 1797 1798static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud, 1799 unsigned long addr, unsigned long end, 1800 pte_fn_t fn, void *data) 1801{ 1802 pmd_t *pmd; 1803 unsigned long next; 1804 int err; 1805 1806 BUG_ON(pud_huge(*pud)); 1807 1808 pmd = pmd_alloc(mm, pud, addr); 1809 if (!pmd) 1810 return -ENOMEM; 1811 do { 1812 next = pmd_addr_end(addr, end); 1813 err = apply_to_pte_range(mm, pmd, addr, next, fn, data); 1814 if (err) 1815 break; 1816 } while (pmd++, addr = next, addr != end); 1817 return err; 1818} 1819 1820static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd, 1821 unsigned long addr, unsigned long end, 1822 pte_fn_t fn, void *data) 1823{ 1824 pud_t *pud; 1825 unsigned long next; 1826 int err; 1827 1828 pud = pud_alloc(mm, pgd, addr); 1829 if (!pud) 1830 return -ENOMEM; 1831 do { 1832 next = pud_addr_end(addr, end); 1833 err = apply_to_pmd_range(mm, pud, addr, next, fn, data); 1834 if (err) 1835 break; 1836 } while (pud++, addr = next, addr != end); 1837 return err; 1838} 1839 1840/* 1841 * Scan a region of virtual memory, filling in page tables as necessary 1842 * and calling a provided function on each leaf page table. 1843 */ 1844int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 1845 unsigned long size, pte_fn_t fn, void *data) 1846{ 1847 pgd_t *pgd; 1848 unsigned long next; 1849 unsigned long start = addr, end = addr + size; 1850 int err; 1851 1852 BUG_ON(addr >= end); 1853 mmu_notifier_invalidate_range_start(mm, start, end); 1854 pgd = pgd_offset(mm, addr); 1855 do { 1856 next = pgd_addr_end(addr, end); 1857 err = apply_to_pud_range(mm, pgd, addr, next, fn, data); 1858 if (err) 1859 break; 1860 } while (pgd++, addr = next, addr != end); 1861 mmu_notifier_invalidate_range_end(mm, start, end); 1862 return err; 1863} 1864EXPORT_SYMBOL_GPL(apply_to_page_range); 1865 1866/* 1867 * handle_pte_fault chooses page fault handler according to an entry 1868 * which was read non-atomically. Before making any commitment, on 1869 * those architectures or configurations (e.g. i386 with PAE) which 1870 * might give a mix of unmatched parts, do_swap_page and do_file_page 1871 * must check under lock before unmapping the pte and proceeding 1872 * (but do_wp_page is only called after already making such a check; 1873 * and do_anonymous_page and do_no_page can safely check later on). 1874 */ 1875static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd, 1876 pte_t *page_table, pte_t orig_pte) 1877{ 1878 int same = 1; 1879#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT) 1880 if (sizeof(pte_t) > sizeof(unsigned long)) { 1881 spinlock_t *ptl = pte_lockptr(mm, pmd); 1882 spin_lock(ptl); 1883 same = pte_same(*page_table, orig_pte); 1884 spin_unlock(ptl); 1885 } 1886#endif 1887 pte_unmap(page_table); 1888 return same; 1889} 1890 1891/* 1892 * Do pte_mkwrite, but only if the vma says VM_WRITE. We do this when 1893 * servicing faults for write access. In the normal case, do always want 1894 * pte_mkwrite. But get_user_pages can cause write faults for mappings 1895 * that do not have writing enabled, when used by access_process_vm. 1896 */ 1897static inline pte_t maybe_mkwrite(pte_t pte, struct vm_area_struct *vma) 1898{ 1899 if (likely(vma->vm_flags & VM_WRITE)) 1900 pte = pte_mkwrite(pte); 1901 return pte; 1902} 1903 1904static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma) 1905{ 1906 /* 1907 * If the source page was a PFN mapping, we don't have 1908 * a "struct page" for it. We do a best-effort copy by 1909 * just copying from the original user address. If that 1910 * fails, we just zero-fill it. Live with it. 1911 */ 1912 if (unlikely(!src)) { 1913 void *kaddr = kmap_atomic(dst, KM_USER0); 1914 void __user *uaddr = (void __user *)(va & PAGE_MASK); 1915 1916 /* 1917 * This really shouldn't fail, because the page is there 1918 * in the page tables. But it might just be unreadable, 1919 * in which case we just give up and fill the result with 1920 * zeroes. 1921 */ 1922 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) 1923 memset(kaddr, 0, PAGE_SIZE); 1924 kunmap_atomic(kaddr, KM_USER0); 1925 flush_dcache_page(dst); 1926 } else 1927 copy_user_highpage(dst, src, va, vma); 1928} 1929 1930/* 1931 * This routine handles present pages, when users try to write 1932 * to a shared page. It is done by copying the page to a new address 1933 * and decrementing the shared-page counter for the old page. 1934 * 1935 * Note that this routine assumes that the protection checks have been 1936 * done by the caller (the low-level page fault routine in most cases). 1937 * Thus we can safely just mark it writable once we've done any necessary 1938 * COW. 1939 * 1940 * We also mark the page dirty at this point even though the page will 1941 * change only once the write actually happens. This avoids a few races, 1942 * and potentially makes it more efficient. 1943 * 1944 * We enter with non-exclusive mmap_sem (to exclude vma changes, 1945 * but allow concurrent faults), with pte both mapped and locked. 1946 * We return with mmap_sem still held, but pte unmapped and unlocked. 1947 */ 1948static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, 1949 unsigned long address, pte_t *page_table, pmd_t *pmd, 1950 spinlock_t *ptl, pte_t orig_pte) 1951{ 1952 struct page *old_page, *new_page; 1953 pte_t entry; 1954 int reuse = 0, ret = 0; 1955 int page_mkwrite = 0; 1956 struct page *dirty_page = NULL; 1957 1958 old_page = vm_normal_page(vma, address, orig_pte); 1959 if (!old_page) { 1960 /* 1961 * VM_MIXEDMAP !pfn_valid() case 1962 * 1963 * We should not cow pages in a shared writeable mapping. 1964 * Just mark the pages writable as we can't do any dirty 1965 * accounting on raw pfn maps. 1966 */ 1967 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 1968 (VM_WRITE|VM_SHARED)) 1969 goto reuse; 1970 goto gotten; 1971 } 1972 1973 /* 1974 * Take out anonymous pages first, anonymous shared vmas are 1975 * not dirty accountable. 1976 */ 1977 if (PageAnon(old_page)) { 1978 if (!trylock_page(old_page)) { 1979 page_cache_get(old_page); 1980 pte_unmap_unlock(page_table, ptl); 1981 lock_page(old_page); 1982 page_table = pte_offset_map_lock(mm, pmd, address, 1983 &ptl); 1984 if (!pte_same(*page_table, orig_pte)) { 1985 unlock_page(old_page); 1986 page_cache_release(old_page); 1987 goto unlock; 1988 } 1989 page_cache_release(old_page); 1990 } 1991 reuse = reuse_swap_page(old_page); 1992 unlock_page(old_page); 1993 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) == 1994 (VM_WRITE|VM_SHARED))) { 1995 /* 1996 * Only catch write-faults on shared writable pages, 1997 * read-only shared pages can get COWed by 1998 * get_user_pages(.write=1, .force=1). 1999 */ 2000 if (vma->vm_ops && vma->vm_ops->page_mkwrite) { 2001 struct vm_fault vmf; 2002 int tmp; 2003 2004 vmf.virtual_address = (void __user *)(address & 2005 PAGE_MASK); 2006 vmf.pgoff = old_page->index; 2007 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2008 vmf.page = old_page; 2009 2010 /* 2011 * Notify the address space that the page is about to 2012 * become writable so that it can prohibit this or wait 2013 * for the page to get into an appropriate state. 2014 * 2015 * We do this without the lock held, so that it can 2016 * sleep if it needs to. 2017 */ 2018 page_cache_get(old_page); 2019 pte_unmap_unlock(page_table, ptl); 2020 2021 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 2022 if (unlikely(tmp & 2023 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2024 ret = tmp; 2025 goto unwritable_page; 2026 } 2027 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 2028 lock_page(old_page); 2029 if (!old_page->mapping) { 2030 ret = 0; /* retry the fault */ 2031 unlock_page(old_page); 2032 goto unwritable_page; 2033 } 2034 } else 2035 VM_BUG_ON(!PageLocked(old_page)); 2036 2037 /* 2038 * Since we dropped the lock we need to revalidate 2039 * the PTE as someone else may have changed it. If 2040 * they did, we just return, as we can count on the 2041 * MMU to tell us if they didn't also make it writable. 2042 */ 2043 page_table = pte_offset_map_lock(mm, pmd, address, 2044 &ptl); 2045 if (!pte_same(*page_table, orig_pte)) { 2046 unlock_page(old_page); 2047 page_cache_release(old_page); 2048 goto unlock; 2049 } 2050 2051 page_mkwrite = 1; 2052 } 2053 dirty_page = old_page; 2054 get_page(dirty_page); 2055 reuse = 1; 2056 } 2057 2058 if (reuse) { 2059reuse: 2060 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2061 entry = pte_mkyoung(orig_pte); 2062 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2063 if (ptep_set_access_flags(vma, address, page_table, entry,1)) 2064 update_mmu_cache(vma, address, entry); 2065 ret |= VM_FAULT_WRITE; 2066 goto unlock; 2067 } 2068 2069 /* 2070 * Ok, we need to copy. Oh, well.. 2071 */ 2072 page_cache_get(old_page); 2073gotten: 2074 pte_unmap_unlock(page_table, ptl); 2075 2076 if (unlikely(anon_vma_prepare(vma))) 2077 goto oom; 2078 VM_BUG_ON(old_page == ZERO_PAGE(0)); 2079 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); 2080 if (!new_page) 2081 goto oom; 2082 /* 2083 * Don't let another task, with possibly unlocked vma, 2084 * keep the mlocked page. 2085 */ 2086 if ((vma->vm_flags & VM_LOCKED) && old_page) { 2087 lock_page(old_page); /* for LRU manipulation */ 2088 clear_page_mlock(old_page); 2089 unlock_page(old_page); 2090 } 2091 cow_user_page(new_page, old_page, address, vma); 2092 __SetPageUptodate(new_page); 2093 2094 if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) 2095 goto oom_free_new; 2096 2097 /* 2098 * Re-check the pte - we dropped the lock 2099 */ 2100 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2101 if (likely(pte_same(*page_table, orig_pte))) { 2102 if (old_page) { 2103 if (!PageAnon(old_page)) { 2104 dec_mm_counter(mm, file_rss); 2105 inc_mm_counter(mm, anon_rss); 2106 } 2107 } else 2108 inc_mm_counter(mm, anon_rss); 2109 flush_cache_page(vma, address, pte_pfn(orig_pte)); 2110 entry = mk_pte(new_page, vma->vm_page_prot); 2111 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2112 /* 2113 * Clear the pte entry and flush it first, before updating the 2114 * pte with the new entry. This will avoid a race condition 2115 * seen in the presence of one thread doing SMC and another 2116 * thread doing COW. 2117 */ 2118 ptep_clear_flush(vma, address, page_table); 2119 page_add_new_anon_rmap(new_page, vma, address); 2120 /* 2121 * We call the notify macro here because, when using secondary 2122 * mmu page tables (such as kvm shadow page tables), we want the 2123 * new page to be mapped directly into the secondary page table. 2124 */ 2125 set_pte_at_notify(mm, address, page_table, entry); 2126 update_mmu_cache(vma, address, entry); 2127 if (old_page) { 2128 /* 2129 * Only after switching the pte to the new page may 2130 * we remove the mapcount here. Otherwise another 2131 * process may come and find the rmap count decremented 2132 * before the pte is switched to the new page, and 2133 * "reuse" the old page writing into it while our pte 2134 * here still points into it and can be read by other 2135 * threads. 2136 * 2137 * The critical issue is to order this 2138 * page_remove_rmap with the ptp_clear_flush above. 2139 * Those stores are ordered by (if nothing else,) 2140 * the barrier present in the atomic_add_negative 2141 * in page_remove_rmap. 2142 * 2143 * Then the TLB flush in ptep_clear_flush ensures that 2144 * no process can access the old page before the 2145 * decremented mapcount is visible. And the old page 2146 * cannot be reused until after the decremented 2147 * mapcount is visible. So transitively, TLBs to 2148 * old page will be flushed before it can be reused. 2149 */ 2150 page_remove_rmap(old_page); 2151 } 2152 2153 /* Free the old page.. */ 2154 new_page = old_page; 2155 ret |= VM_FAULT_WRITE; 2156 } else 2157 mem_cgroup_uncharge_page(new_page); 2158 2159 if (new_page) 2160 page_cache_release(new_page); 2161 if (old_page) 2162 page_cache_release(old_page); 2163unlock: 2164 pte_unmap_unlock(page_table, ptl); 2165 if (dirty_page) { 2166 /* 2167 * Yes, Virginia, this is actually required to prevent a race 2168 * with clear_page_dirty_for_io() from clearing the page dirty 2169 * bit after it clear all dirty ptes, but before a racing 2170 * do_wp_page installs a dirty pte. 2171 * 2172 * do_no_page is protected similarly. 2173 */ 2174 if (!page_mkwrite) { 2175 wait_on_page_locked(dirty_page); 2176 set_page_dirty_balance(dirty_page, page_mkwrite); 2177 } 2178 put_page(dirty_page); 2179 if (page_mkwrite) { 2180 struct address_space *mapping = dirty_page->mapping; 2181 2182 set_page_dirty(dirty_page); 2183 unlock_page(dirty_page); 2184 page_cache_release(dirty_page); 2185 if (mapping) { 2186 /* 2187 * Some device drivers do not set page.mapping 2188 * but still dirty their pages 2189 */ 2190 balance_dirty_pages_ratelimited(mapping); 2191 } 2192 } 2193 2194 /* file_update_time outside page_lock */ 2195 if (vma->vm_file) 2196 file_update_time(vma->vm_file); 2197 } 2198 return ret; 2199oom_free_new: 2200 page_cache_release(new_page); 2201oom: 2202 if (old_page) { 2203 if (page_mkwrite) { 2204 unlock_page(old_page); 2205 page_cache_release(old_page); 2206 } 2207 page_cache_release(old_page); 2208 } 2209 return VM_FAULT_OOM; 2210 2211unwritable_page: 2212 page_cache_release(old_page); 2213 return ret; 2214} 2215 2216/* 2217 * Helper functions for unmap_mapping_range(). 2218 * 2219 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __ 2220 * 2221 * We have to restart searching the prio_tree whenever we drop the lock, 2222 * since the iterator is only valid while the lock is held, and anyway 2223 * a later vma might be split and reinserted earlier while lock dropped. 2224 * 2225 * The list of nonlinear vmas could be handled more efficiently, using 2226 * a placeholder, but handle it in the same way until a need is shown. 2227 * It is important to search the prio_tree before nonlinear list: a vma 2228 * may become nonlinear and be shifted from prio_tree to nonlinear list 2229 * while the lock is dropped; but never shifted from list to prio_tree. 2230 * 2231 * In order to make forward progress despite restarting the search, 2232 * vm_truncate_count is used to mark a vma as now dealt with, so we can 2233 * quickly skip it next time around. Since the prio_tree search only 2234 * shows us those vmas affected by unmapping the range in question, we 2235 * can't efficiently keep all vmas in step with mapping->truncate_count: 2236 * so instead reset them all whenever it wraps back to 0 (then go to 1). 2237 * mapping->truncate_count and vma->vm_truncate_count are protected by 2238 * i_mmap_lock. 2239 * 2240 * In order to make forward progress despite repeatedly restarting some 2241 * large vma, note the restart_addr from unmap_vmas when it breaks out: 2242 * and restart from that address when we reach that vma again. It might 2243 * have been split or merged, shrunk or extended, but never shifted: so 2244 * restart_addr remains valid so long as it remains in the vma's range. 2245 * unmap_mapping_range forces truncate_count to leap over page-aligned 2246 * values so we can save vma's restart_addr in its truncate_count field. 2247 */ 2248#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK)) 2249 2250static void reset_vma_truncate_counts(struct address_space *mapping) 2251{ 2252 struct vm_area_struct *vma; 2253 struct prio_tree_iter iter; 2254 2255 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) 2256 vma->vm_truncate_count = 0; 2257 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) 2258 vma->vm_truncate_count = 0; 2259} 2260 2261static int unmap_mapping_range_vma(struct vm_area_struct *vma, 2262 unsigned long start_addr, unsigned long end_addr, 2263 struct zap_details *details) 2264{ 2265 unsigned long restart_addr; 2266 int need_break; 2267 2268 /* 2269 * files that support invalidating or truncating portions of the 2270 * file from under mmaped areas must have their ->fault function 2271 * return a locked page (and set VM_FAULT_LOCKED in the return). 2272 * This provides synchronisation against concurrent unmapping here. 2273 */ 2274 2275again: 2276 restart_addr = vma->vm_truncate_count; 2277 if (is_restart_addr(restart_addr) && start_addr < restart_addr) { 2278 start_addr = restart_addr; 2279 if (start_addr >= end_addr) { 2280 /* Top of vma has been split off since last time */ 2281 vma->vm_truncate_count = details->truncate_count; 2282 return 0; 2283 } 2284 } 2285 2286 restart_addr = zap_page_range(vma, start_addr, 2287 end_addr - start_addr, details); 2288 need_break = need_resched() || spin_needbreak(details->i_mmap_lock); 2289 2290 if (restart_addr >= end_addr) { 2291 /* We have now completed this vma: mark it so */ 2292 vma->vm_truncate_count = details->truncate_count; 2293 if (!need_break) 2294 return 0; 2295 } else { 2296 /* Note restart_addr in vma's truncate_count field */ 2297 vma->vm_truncate_count = restart_addr; 2298 if (!need_break) 2299 goto again; 2300 } 2301 2302 spin_unlock(details->i_mmap_lock); 2303 cond_resched(); 2304 spin_lock(details->i_mmap_lock); 2305 return -EINTR; 2306} 2307 2308static inline void unmap_mapping_range_tree(struct prio_tree_root *root, 2309 struct zap_details *details) 2310{ 2311 struct vm_area_struct *vma; 2312 struct prio_tree_iter iter; 2313 pgoff_t vba, vea, zba, zea; 2314 2315restart: 2316 vma_prio_tree_foreach(vma, &iter, root, 2317 details->first_index, details->last_index) { 2318 /* Skip quickly over those we have already dealt with */ 2319 if (vma->vm_truncate_count == details->truncate_count) 2320 continue; 2321 2322 vba = vma->vm_pgoff; 2323 vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1; 2324 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */ 2325 zba = details->first_index; 2326 if (zba < vba) 2327 zba = vba; 2328 zea = details->last_index; 2329 if (zea > vea) 2330 zea = vea; 2331 2332 if (unmap_mapping_range_vma(vma, 2333 ((zba - vba) << PAGE_SHIFT) + vma->vm_start, 2334 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start, 2335 details) < 0) 2336 goto restart; 2337 } 2338} 2339 2340static inline void unmap_mapping_range_list(struct list_head *head, 2341 struct zap_details *details) 2342{ 2343 struct vm_area_struct *vma; 2344 2345 /* 2346 * In nonlinear VMAs there is no correspondence between virtual address 2347 * offset and file offset. So we must perform an exhaustive search 2348 * across *all* the pages in each nonlinear VMA, not just the pages 2349 * whose virtual address lies outside the file truncation point. 2350 */ 2351restart: 2352 list_for_each_entry(vma, head, shared.vm_set.list) { 2353 /* Skip quickly over those we have already dealt with */ 2354 if (vma->vm_truncate_count == details->truncate_count) 2355 continue; 2356 details->nonlinear_vma = vma; 2357 if (unmap_mapping_range_vma(vma, vma->vm_start, 2358 vma->vm_end, details) < 0) 2359 goto restart; 2360 } 2361} 2362 2363/** 2364 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file. 2365 * @mapping: the address space containing mmaps to be unmapped. 2366 * @holebegin: byte in first page to unmap, relative to the start of 2367 * the underlying file. This will be rounded down to a PAGE_SIZE 2368 * boundary. Note that this is different from vmtruncate(), which 2369 * must keep the partial page. In contrast, we must get rid of 2370 * partial pages. 2371 * @holelen: size of prospective hole in bytes. This will be rounded 2372 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the 2373 * end of the file. 2374 * @even_cows: 1 when truncating a file, unmap even private COWed pages; 2375 * but 0 when invalidating pagecache, don't throw away private data. 2376 */ 2377void unmap_mapping_range(struct address_space *mapping, 2378 loff_t const holebegin, loff_t const holelen, int even_cows) 2379{ 2380 struct zap_details details; 2381 pgoff_t hba = holebegin >> PAGE_SHIFT; 2382 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2383 2384 /* Check for overflow. */ 2385 if (sizeof(holelen) > sizeof(hlen)) { 2386 long long holeend = 2387 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT; 2388 if (holeend & ~(long long)ULONG_MAX) 2389 hlen = ULONG_MAX - hba + 1; 2390 } 2391 2392 details.check_mapping = even_cows? NULL: mapping; 2393 details.nonlinear_vma = NULL; 2394 details.first_index = hba; 2395 details.last_index = hba + hlen - 1; 2396 if (details.last_index < details.first_index) 2397 details.last_index = ULONG_MAX; 2398 details.i_mmap_lock = &mapping->i_mmap_lock; 2399 2400 spin_lock(&mapping->i_mmap_lock); 2401 2402 /* Protect against endless unmapping loops */ 2403 mapping->truncate_count++; 2404 if (unlikely(is_restart_addr(mapping->truncate_count))) { 2405 if (mapping->truncate_count == 0) 2406 reset_vma_truncate_counts(mapping); 2407 mapping->truncate_count++; 2408 } 2409 details.truncate_count = mapping->truncate_count; 2410 2411 if (unlikely(!prio_tree_empty(&mapping->i_mmap))) 2412 unmap_mapping_range_tree(&mapping->i_mmap, &details); 2413 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear))) 2414 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details); 2415 spin_unlock(&mapping->i_mmap_lock); 2416} 2417EXPORT_SYMBOL(unmap_mapping_range); 2418 2419/** 2420 * vmtruncate - unmap mappings "freed" by truncate() syscall 2421 * @inode: inode of the file used 2422 * @offset: file offset to start truncating 2423 * 2424 * NOTE! We have to be ready to update the memory sharing 2425 * between the file and the memory map for a potential last 2426 * incomplete page. Ugly, but necessary. 2427 */ 2428int vmtruncate(struct inode * inode, loff_t offset) 2429{ 2430 if (inode->i_size < offset) { 2431 unsigned long limit; 2432 2433 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 2434 if (limit != RLIM_INFINITY && offset > limit) 2435 goto out_sig; 2436 if (offset > inode->i_sb->s_maxbytes) 2437 goto out_big; 2438 i_size_write(inode, offset); 2439 } else { 2440 struct address_space *mapping = inode->i_mapping; 2441 2442 /* 2443 * truncation of in-use swapfiles is disallowed - it would 2444 * cause subsequent swapout to scribble on the now-freed 2445 * blocks. 2446 */ 2447 if (IS_SWAPFILE(inode)) 2448 return -ETXTBSY; 2449 i_size_write(inode, offset); 2450 2451 /* 2452 * unmap_mapping_range is called twice, first simply for 2453 * efficiency so that truncate_inode_pages does fewer 2454 * single-page unmaps. However after this first call, and 2455 * before truncate_inode_pages finishes, it is possible for 2456 * private pages to be COWed, which remain after 2457 * truncate_inode_pages finishes, hence the second 2458 * unmap_mapping_range call must be made for correctness. 2459 */ 2460 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 2461 truncate_inode_pages(mapping, offset); 2462 unmap_mapping_range(mapping, offset + PAGE_SIZE - 1, 0, 1); 2463 } 2464 2465 if (inode->i_op->truncate) 2466 inode->i_op->truncate(inode); 2467 return 0; 2468 2469out_sig: 2470 send_sig(SIGXFSZ, current, 0); 2471out_big: 2472 return -EFBIG; 2473} 2474EXPORT_SYMBOL(vmtruncate); 2475 2476int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 2477{ 2478 struct address_space *mapping = inode->i_mapping; 2479 2480 /* 2481 * If the underlying filesystem is not going to provide 2482 * a way to truncate a range of blocks (punch a hole) - 2483 * we should return failure right now. 2484 */ 2485 if (!inode->i_op->truncate_range) 2486 return -ENOSYS; 2487 2488 mutex_lock(&inode->i_mutex); 2489 down_write(&inode->i_alloc_sem); 2490 unmap_mapping_range(mapping, offset, (end - offset), 1); 2491 truncate_inode_pages_range(mapping, offset, end); 2492 unmap_mapping_range(mapping, offset, (end - offset), 1); 2493 inode->i_op->truncate_range(inode, offset, end); 2494 up_write(&inode->i_alloc_sem); 2495 mutex_unlock(&inode->i_mutex); 2496 2497 return 0; 2498} 2499 2500/* 2501 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2502 * but allow concurrent faults), and pte mapped but not yet locked. 2503 * We return with mmap_sem still held, but pte unmapped and unlocked. 2504 */ 2505static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 2506 unsigned long address, pte_t *page_table, pmd_t *pmd, 2507 unsigned int flags, pte_t orig_pte) 2508{ 2509 spinlock_t *ptl; 2510 struct page *page; 2511 swp_entry_t entry; 2512 pte_t pte; 2513 struct mem_cgroup *ptr = NULL; 2514 int ret = 0; 2515 2516 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2517 goto out; 2518 2519 entry = pte_to_swp_entry(orig_pte); 2520 if (is_migration_entry(entry)) { 2521 migration_entry_wait(mm, pmd, address); 2522 goto out; 2523 } 2524 delayacct_set_flag(DELAYACCT_PF_SWAPIN); 2525 page = lookup_swap_cache(entry); 2526 if (!page) { 2527 grab_swap_token(mm); /* Contend for token _before_ read-in */ 2528 page = swapin_readahead(entry, 2529 GFP_HIGHUSER_MOVABLE, vma, address); 2530 if (!page) { 2531 /* 2532 * Back out if somebody else faulted in this pte 2533 * while we released the pte lock. 2534 */ 2535 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2536 if (likely(pte_same(*page_table, orig_pte))) 2537 ret = VM_FAULT_OOM; 2538 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2539 goto unlock; 2540 } 2541 2542 /* Had to read the page from swap area: Major fault */ 2543 ret = VM_FAULT_MAJOR; 2544 count_vm_event(PGMAJFAULT); 2545 } 2546 2547 lock_page(page); 2548 delayacct_clear_flag(DELAYACCT_PF_SWAPIN); 2549 2550 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) { 2551 ret = VM_FAULT_OOM; 2552 goto out_page; 2553 } 2554 2555 /* 2556 * Back out if somebody else already faulted in this pte. 2557 */ 2558 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2559 if (unlikely(!pte_same(*page_table, orig_pte))) 2560 goto out_nomap; 2561 2562 if (unlikely(!PageUptodate(page))) { 2563 ret = VM_FAULT_SIGBUS; 2564 goto out_nomap; 2565 } 2566 2567 /* 2568 * The page isn't present yet, go ahead with the fault. 2569 * 2570 * Be careful about the sequence of operations here. 2571 * To get its accounting right, reuse_swap_page() must be called 2572 * while the page is counted on swap but not yet in mapcount i.e. 2573 * before page_add_anon_rmap() and swap_free(); try_to_free_swap() 2574 * must be called after the swap_free(), or it will never succeed. 2575 * Because delete_from_swap_page() may be called by reuse_swap_page(), 2576 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry 2577 * in page->private. In this case, a record in swap_cgroup is silently 2578 * discarded at swap_free(). 2579 */ 2580 2581 inc_mm_counter(mm, anon_rss); 2582 pte = mk_pte(page, vma->vm_page_prot); 2583 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) { 2584 pte = maybe_mkwrite(pte_mkdirty(pte), vma); 2585 flags &= ~FAULT_FLAG_WRITE; 2586 } 2587 flush_icache_page(vma, page); 2588 set_pte_at(mm, address, page_table, pte); 2589 page_add_anon_rmap(page, vma, address); 2590 /* It's better to call commit-charge after rmap is established */ 2591 mem_cgroup_commit_charge_swapin(page, ptr); 2592 2593 swap_free(entry); 2594 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page)) 2595 try_to_free_swap(page); 2596 unlock_page(page); 2597 2598 if (flags & FAULT_FLAG_WRITE) { 2599 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte); 2600 if (ret & VM_FAULT_ERROR) 2601 ret &= VM_FAULT_ERROR; 2602 goto out; 2603 } 2604 2605 /* No need to invalidate - it was non-present before */ 2606 update_mmu_cache(vma, address, pte); 2607unlock: 2608 pte_unmap_unlock(page_table, ptl); 2609out: 2610 return ret; 2611out_nomap: 2612 mem_cgroup_cancel_charge_swapin(ptr); 2613 pte_unmap_unlock(page_table, ptl); 2614out_page: 2615 unlock_page(page); 2616 page_cache_release(page); 2617 return ret; 2618} 2619 2620/* 2621 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2622 * but allow concurrent faults), and pte mapped but not yet locked. 2623 * We return with mmap_sem still held, but pte unmapped and unlocked. 2624 */ 2625static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma, 2626 unsigned long address, pte_t *page_table, pmd_t *pmd, 2627 unsigned int flags) 2628{ 2629 struct page *page; 2630 spinlock_t *ptl; 2631 pte_t entry; 2632 2633 /* Allocate our own private page. */ 2634 pte_unmap(page_table); 2635 2636 if (unlikely(anon_vma_prepare(vma))) 2637 goto oom; 2638 page = alloc_zeroed_user_highpage_movable(vma, address); 2639 if (!page) 2640 goto oom; 2641 __SetPageUptodate(page); 2642 2643 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) 2644 goto oom_free_page; 2645 2646 entry = mk_pte(page, vma->vm_page_prot); 2647 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2648 2649 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2650 if (!pte_none(*page_table)) 2651 goto release; 2652 inc_mm_counter(mm, anon_rss); 2653 page_add_new_anon_rmap(page, vma, address); 2654 set_pte_at(mm, address, page_table, entry); 2655 2656 /* No need to invalidate - it was non-present before */ 2657 update_mmu_cache(vma, address, entry); 2658unlock: 2659 pte_unmap_unlock(page_table, ptl); 2660 return 0; 2661release: 2662 mem_cgroup_uncharge_page(page); 2663 page_cache_release(page); 2664 goto unlock; 2665oom_free_page: 2666 page_cache_release(page); 2667oom: 2668 return VM_FAULT_OOM; 2669} 2670 2671/* 2672 * __do_fault() tries to create a new page mapping. It aggressively 2673 * tries to share with existing pages, but makes a separate copy if 2674 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid 2675 * the next page fault. 2676 * 2677 * As this is called only for pages that do not currently exist, we 2678 * do not need to flush old virtual caches or the TLB. 2679 * 2680 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2681 * but allow concurrent faults), and pte neither mapped nor locked. 2682 * We return with mmap_sem still held, but pte unmapped and unlocked. 2683 */ 2684static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2685 unsigned long address, pmd_t *pmd, 2686 pgoff_t pgoff, unsigned int flags, pte_t orig_pte) 2687{ 2688 pte_t *page_table; 2689 spinlock_t *ptl; 2690 struct page *page; 2691 pte_t entry; 2692 int anon = 0; 2693 int charged = 0; 2694 struct page *dirty_page = NULL; 2695 struct vm_fault vmf; 2696 int ret; 2697 int page_mkwrite = 0; 2698 2699 vmf.virtual_address = (void __user *)(address & PAGE_MASK); 2700 vmf.pgoff = pgoff; 2701 vmf.flags = flags; 2702 vmf.page = NULL; 2703 2704 ret = vma->vm_ops->fault(vma, &vmf); 2705 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) 2706 return ret; 2707 2708 /* 2709 * For consistency in subsequent calls, make the faulted page always 2710 * locked. 2711 */ 2712 if (unlikely(!(ret & VM_FAULT_LOCKED))) 2713 lock_page(vmf.page); 2714 else 2715 VM_BUG_ON(!PageLocked(vmf.page)); 2716 2717 /* 2718 * Should we do an early C-O-W break? 2719 */ 2720 page = vmf.page; 2721 if (flags & FAULT_FLAG_WRITE) { 2722 if (!(vma->vm_flags & VM_SHARED)) { 2723 anon = 1; 2724 if (unlikely(anon_vma_prepare(vma))) { 2725 ret = VM_FAULT_OOM; 2726 goto out; 2727 } 2728 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, 2729 vma, address); 2730 if (!page) { 2731 ret = VM_FAULT_OOM; 2732 goto out; 2733 } 2734 if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) { 2735 ret = VM_FAULT_OOM; 2736 page_cache_release(page); 2737 goto out; 2738 } 2739 charged = 1; 2740 /* 2741 * Don't let another task, with possibly unlocked vma, 2742 * keep the mlocked page. 2743 */ 2744 if (vma->vm_flags & VM_LOCKED) 2745 clear_page_mlock(vmf.page); 2746 copy_user_highpage(page, vmf.page, address, vma); 2747 __SetPageUptodate(page); 2748 } else { 2749 /* 2750 * If the page will be shareable, see if the backing 2751 * address space wants to know that the page is about 2752 * to become writable 2753 */ 2754 if (vma->vm_ops->page_mkwrite) { 2755 int tmp; 2756 2757 unlock_page(page); 2758 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE; 2759 tmp = vma->vm_ops->page_mkwrite(vma, &vmf); 2760 if (unlikely(tmp & 2761 (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) { 2762 ret = tmp; 2763 goto unwritable_page; 2764 } 2765 if (unlikely(!(tmp & VM_FAULT_LOCKED))) { 2766 lock_page(page); 2767 if (!page->mapping) { 2768 ret = 0; /* retry the fault */ 2769 unlock_page(page); 2770 goto unwritable_page; 2771 } 2772 } else 2773 VM_BUG_ON(!PageLocked(page)); 2774 page_mkwrite = 1; 2775 } 2776 } 2777 2778 } 2779 2780 page_table = pte_offset_map_lock(mm, pmd, address, &ptl); 2781 2782 /* 2783 * This silly early PAGE_DIRTY setting removes a race 2784 * due to the bad i386 page protection. But it's valid 2785 * for other architectures too. 2786 * 2787 * Note that if FAULT_FLAG_WRITE is set, we either now have 2788 * an exclusive copy of the page, or this is a shared mapping, 2789 * so we can make it writable and dirty to avoid having to 2790 * handle that later. 2791 */ 2792 /* Only go through if we didn't race with anybody else... */ 2793 if (likely(pte_same(*page_table, orig_pte))) { 2794 flush_icache_page(vma, page); 2795 entry = mk_pte(page, vma->vm_page_prot); 2796 if (flags & FAULT_FLAG_WRITE) 2797 entry = maybe_mkwrite(pte_mkdirty(entry), vma); 2798 if (anon) { 2799 inc_mm_counter(mm, anon_rss); 2800 page_add_new_anon_rmap(page, vma, address); 2801 } else { 2802 inc_mm_counter(mm, file_rss); 2803 page_add_file_rmap(page); 2804 if (flags & FAULT_FLAG_WRITE) { 2805 dirty_page = page; 2806 get_page(dirty_page); 2807 } 2808 } 2809 set_pte_at(mm, address, page_table, entry); 2810 2811 /* no need to invalidate: a not-present page won't be cached */ 2812 update_mmu_cache(vma, address, entry); 2813 } else { 2814 if (charged) 2815 mem_cgroup_uncharge_page(page); 2816 if (anon) 2817 page_cache_release(page); 2818 else 2819 anon = 1; /* no anon but release faulted_page */ 2820 } 2821 2822 pte_unmap_unlock(page_table, ptl); 2823 2824out: 2825 if (dirty_page) { 2826 struct address_space *mapping = page->mapping; 2827 2828 if (set_page_dirty(dirty_page)) 2829 page_mkwrite = 1; 2830 unlock_page(dirty_page); 2831 put_page(dirty_page); 2832 if (page_mkwrite && mapping) { 2833 /* 2834 * Some device drivers do not set page.mapping but still 2835 * dirty their pages 2836 */ 2837 balance_dirty_pages_ratelimited(mapping); 2838 } 2839 2840 /* file_update_time outside page_lock */ 2841 if (vma->vm_file) 2842 file_update_time(vma->vm_file); 2843 } else { 2844 unlock_page(vmf.page); 2845 if (anon) 2846 page_cache_release(vmf.page); 2847 } 2848 2849 return ret; 2850 2851unwritable_page: 2852 page_cache_release(page); 2853 return ret; 2854} 2855 2856static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2857 unsigned long address, pte_t *page_table, pmd_t *pmd, 2858 unsigned int flags, pte_t orig_pte) 2859{ 2860 pgoff_t pgoff = (((address & PAGE_MASK) 2861 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 2862 2863 pte_unmap(page_table); 2864 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2865} 2866 2867/* 2868 * Fault of a previously existing named mapping. Repopulate the pte 2869 * from the encoded file_pte if possible. This enables swappable 2870 * nonlinear vmas. 2871 * 2872 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2873 * but allow concurrent faults), and pte mapped but not yet locked. 2874 * We return with mmap_sem still held, but pte unmapped and unlocked. 2875 */ 2876static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2877 unsigned long address, pte_t *page_table, pmd_t *pmd, 2878 unsigned int flags, pte_t orig_pte) 2879{ 2880 pgoff_t pgoff; 2881 2882 flags |= FAULT_FLAG_NONLINEAR; 2883 2884 if (!pte_unmap_same(mm, pmd, page_table, orig_pte)) 2885 return 0; 2886 2887 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) { 2888 /* 2889 * Page table corrupted: show pte and kill process. 2890 */ 2891 print_bad_pte(vma, address, orig_pte, NULL); 2892 return VM_FAULT_OOM; 2893 } 2894 2895 pgoff = pte_to_pgoff(orig_pte); 2896 return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte); 2897} 2898 2899/* 2900 * These routines also need to handle stuff like marking pages dirty 2901 * and/or accessed for architectures that don't do it in hardware (most 2902 * RISC architectures). The early dirtying is also good on the i386. 2903 * 2904 * There is also a hook called "update_mmu_cache()" that architectures 2905 * with external mmu caches can use to update those (ie the Sparc or 2906 * PowerPC hashed page tables that act as extended TLBs). 2907 * 2908 * We enter with non-exclusive mmap_sem (to exclude vma changes, 2909 * but allow concurrent faults), and pte mapped but not yet locked. 2910 * We return with mmap_sem still held, but pte unmapped and unlocked. 2911 */ 2912static inline int handle_pte_fault(struct mm_struct *mm, 2913 struct vm_area_struct *vma, unsigned long address, 2914 pte_t *pte, pmd_t *pmd, unsigned int flags) 2915{ 2916 pte_t entry; 2917 spinlock_t *ptl; 2918 2919 entry = *pte; 2920 if (!pte_present(entry)) { 2921 if (pte_none(entry)) { 2922 if (vma->vm_ops) { 2923 if (likely(vma->vm_ops->fault)) 2924 return do_linear_fault(mm, vma, address, 2925 pte, pmd, flags, entry); 2926 } 2927 return do_anonymous_page(mm, vma, address, 2928 pte, pmd, flags); 2929 } 2930 if (pte_file(entry)) 2931 return do_nonlinear_fault(mm, vma, address, 2932 pte, pmd, flags, entry); 2933 return do_swap_page(mm, vma, address, 2934 pte, pmd, flags, entry); 2935 } 2936 2937 ptl = pte_lockptr(mm, pmd); 2938 spin_lock(ptl); 2939 if (unlikely(!pte_same(*pte, entry))) 2940 goto unlock; 2941 if (flags & FAULT_FLAG_WRITE) { 2942 if (!pte_write(entry)) 2943 return do_wp_page(mm, vma, address, 2944 pte, pmd, ptl, entry); 2945 entry = pte_mkdirty(entry); 2946 } 2947 entry = pte_mkyoung(entry); 2948 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) { 2949 update_mmu_cache(vma, address, entry); 2950 } else { 2951 /* 2952 * This is needed only for protection faults but the arch code 2953 * is not yet telling us if this is a protection fault or not. 2954 * This still avoids useless tlb flushes for .text page faults 2955 * with threads. 2956 */ 2957 if (flags & FAULT_FLAG_WRITE) 2958 flush_tlb_page(vma, address); 2959 } 2960unlock: 2961 pte_unmap_unlock(pte, ptl); 2962 return 0; 2963} 2964 2965/* 2966 * By the time we get here, we already hold the mm semaphore 2967 */ 2968int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 2969 unsigned long address, unsigned int flags) 2970{ 2971 pgd_t *pgd; 2972 pud_t *pud; 2973 pmd_t *pmd; 2974 pte_t *pte; 2975 2976 __set_current_state(TASK_RUNNING); 2977 2978 count_vm_event(PGFAULT); 2979 2980 if (unlikely(is_vm_hugetlb_page(vma))) 2981 return hugetlb_fault(mm, vma, address, flags); 2982 2983 pgd = pgd_offset(mm, address); 2984 pud = pud_alloc(mm, pgd, address); 2985 if (!pud) 2986 return VM_FAULT_OOM; 2987 pmd = pmd_alloc(mm, pud, address); 2988 if (!pmd) 2989 return VM_FAULT_OOM; 2990 pte = pte_alloc_map(mm, pmd, address); 2991 if (!pte) 2992 return VM_FAULT_OOM; 2993 2994 return handle_pte_fault(mm, vma, address, pte, pmd, flags); 2995} 2996 2997#ifndef __PAGETABLE_PUD_FOLDED 2998/* 2999 * Allocate page upper directory. 3000 * We've already handled the fast-path in-line. 3001 */ 3002int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address) 3003{ 3004 pud_t *new = pud_alloc_one(mm, address); 3005 if (!new) 3006 return -ENOMEM; 3007 3008 smp_wmb(); /* See comment in __pte_alloc */ 3009 3010 spin_lock(&mm->page_table_lock); 3011 if (pgd_present(*pgd)) /* Another has populated it */ 3012 pud_free(mm, new); 3013 else 3014 pgd_populate(mm, pgd, new); 3015 spin_unlock(&mm->page_table_lock); 3016 return 0; 3017} 3018#endif /* __PAGETABLE_PUD_FOLDED */ 3019 3020#ifndef __PAGETABLE_PMD_FOLDED 3021/* 3022 * Allocate page middle directory. 3023 * We've already handled the fast-path in-line. 3024 */ 3025int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address) 3026{ 3027 pmd_t *new = pmd_alloc_one(mm, address); 3028 if (!new) 3029 return -ENOMEM; 3030 3031 smp_wmb(); /* See comment in __pte_alloc */ 3032 3033 spin_lock(&mm->page_table_lock); 3034#ifndef __ARCH_HAS_4LEVEL_HACK 3035 if (pud_present(*pud)) /* Another has populated it */ 3036 pmd_free(mm, new); 3037 else 3038 pud_populate(mm, pud, new); 3039#else 3040 if (pgd_present(*pud)) /* Another has populated it */ 3041 pmd_free(mm, new); 3042 else 3043 pgd_populate(mm, pud, new); 3044#endif /* __ARCH_HAS_4LEVEL_HACK */ 3045 spin_unlock(&mm->page_table_lock); 3046 return 0; 3047} 3048#endif /* __PAGETABLE_PMD_FOLDED */ 3049 3050int make_pages_present(unsigned long addr, unsigned long end) 3051{ 3052 int ret, len, write; 3053 struct vm_area_struct * vma; 3054 3055 vma = find_vma(current->mm, addr); 3056 if (!vma) 3057 return -ENOMEM; 3058 write = (vma->vm_flags & VM_WRITE) != 0; 3059 BUG_ON(addr >= end); 3060 BUG_ON(end > vma->vm_end); 3061 len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE; 3062 ret = get_user_pages(current, current->mm, addr, 3063 len, write, 0, NULL, NULL); 3064 if (ret < 0) 3065 return ret; 3066 return ret == len ? 0 : -EFAULT; 3067} 3068 3069#if !defined(__HAVE_ARCH_GATE_AREA) 3070 3071#if defined(AT_SYSINFO_EHDR) 3072static struct vm_area_struct gate_vma; 3073 3074static int __init gate_vma_init(void) 3075{ 3076 gate_vma.vm_mm = NULL; 3077 gate_vma.vm_start = FIXADDR_USER_START; 3078 gate_vma.vm_end = FIXADDR_USER_END; 3079 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC; 3080 gate_vma.vm_page_prot = __P101; 3081 /* 3082 * Make sure the vDSO gets into every core dump. 3083 * Dumping its contents makes post-mortem fully interpretable later 3084 * without matching up the same kernel and hardware config to see 3085 * what PC values meant. 3086 */ 3087 gate_vma.vm_flags |= VM_ALWAYSDUMP; 3088 return 0; 3089} 3090__initcall(gate_vma_init); 3091#endif 3092 3093struct vm_area_struct *get_gate_vma(struct task_struct *tsk) 3094{ 3095#ifdef AT_SYSINFO_EHDR 3096 return &gate_vma; 3097#else 3098 return NULL; 3099#endif 3100} 3101 3102int in_gate_area_no_task(unsigned long addr) 3103{ 3104#ifdef AT_SYSINFO_EHDR 3105 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END)) 3106 return 1; 3107#endif 3108 return 0; 3109} 3110 3111#endif /* __HAVE_ARCH_GATE_AREA */ 3112 3113static int follow_pte(struct mm_struct *mm, unsigned long address, 3114 pte_t **ptepp, spinlock_t **ptlp) 3115{ 3116 pgd_t *pgd; 3117 pud_t *pud; 3118 pmd_t *pmd; 3119 pte_t *ptep; 3120 3121 pgd = pgd_offset(mm, address); 3122 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) 3123 goto out; 3124 3125 pud = pud_offset(pgd, address); 3126 if (pud_none(*pud) || unlikely(pud_bad(*pud))) 3127 goto out; 3128 3129 pmd = pmd_offset(pud, address); 3130 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) 3131 goto out; 3132 3133 /* We cannot handle huge page PFN maps. Luckily they don't exist. */ 3134 if (pmd_huge(*pmd)) 3135 goto out; 3136 3137 ptep = pte_offset_map_lock(mm, pmd, address, ptlp); 3138 if (!ptep) 3139 goto out; 3140 if (!pte_present(*ptep)) 3141 goto unlock; 3142 *ptepp = ptep; 3143 return 0; 3144unlock: 3145 pte_unmap_unlock(ptep, *ptlp); 3146out: 3147 return -EINVAL; 3148} 3149 3150/** 3151 * follow_pfn - look up PFN at a user virtual address 3152 * @vma: memory mapping 3153 * @address: user virtual address 3154 * @pfn: location to store found PFN 3155 * 3156 * Only IO mappings and raw PFN mappings are allowed. 3157 * 3158 * Returns zero and the pfn at @pfn on success, -ve otherwise. 3159 */ 3160int follow_pfn(struct vm_area_struct *vma, unsigned long address, 3161 unsigned long *pfn) 3162{ 3163 int ret = -EINVAL; 3164 spinlock_t *ptl; 3165 pte_t *ptep; 3166 3167 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3168 return ret; 3169 3170 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl); 3171 if (ret) 3172 return ret; 3173 *pfn = pte_pfn(*ptep); 3174 pte_unmap_unlock(ptep, ptl); 3175 return 0; 3176} 3177EXPORT_SYMBOL(follow_pfn); 3178 3179#ifdef CONFIG_HAVE_IOREMAP_PROT 3180int follow_phys(struct vm_area_struct *vma, 3181 unsigned long address, unsigned int flags, 3182 unsigned long *prot, resource_size_t *phys) 3183{ 3184 int ret = -EINVAL; 3185 pte_t *ptep, pte; 3186 spinlock_t *ptl; 3187 3188 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 3189 goto out; 3190 3191 if (follow_pte(vma->vm_mm, address, &ptep, &ptl)) 3192 goto out; 3193 pte = *ptep; 3194 3195 if ((flags & FOLL_WRITE) && !pte_write(pte)) 3196 goto unlock; 3197 3198 *prot = pgprot_val(pte_pgprot(pte)); 3199 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT; 3200 3201 ret = 0; 3202unlock: 3203 pte_unmap_unlock(ptep, ptl); 3204out: 3205 return ret; 3206} 3207 3208int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, 3209 void *buf, int len, int write) 3210{ 3211 resource_size_t phys_addr; 3212 unsigned long prot = 0; 3213 void __iomem *maddr; 3214 int offset = addr & (PAGE_SIZE-1); 3215 3216 if (follow_phys(vma, addr, write, &prot, &phys_addr)) 3217 return -EINVAL; 3218 3219 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot); 3220 if (write) 3221 memcpy_toio(maddr + offset, buf, len); 3222 else 3223 memcpy_fromio(buf, maddr + offset, len); 3224 iounmap(maddr); 3225 3226 return len; 3227} 3228#endif 3229 3230/* 3231 * Access another process' address space. 3232 * Source/target buffer must be kernel space, 3233 * Do not walk the page table directly, use get_user_pages 3234 */ 3235int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 3236{ 3237 struct mm_struct *mm; 3238 struct vm_area_struct *vma; 3239 void *old_buf = buf; 3240 3241 mm = get_task_mm(tsk); 3242 if (!mm) 3243 return 0; 3244 3245 down_read(&mm->mmap_sem); 3246 /* ignore errors, just check how much was successfully transferred */ 3247 while (len) { 3248 int bytes, ret, offset; 3249 void *maddr; 3250 struct page *page = NULL; 3251 3252 ret = get_user_pages(tsk, mm, addr, 1, 3253 write, 1, &page, &vma); 3254 if (ret <= 0) { 3255 /* 3256 * Check if this is a VM_IO | VM_PFNMAP VMA, which 3257 * we can access using slightly different code. 3258 */ 3259#ifdef CONFIG_HAVE_IOREMAP_PROT 3260 vma = find_vma(mm, addr); 3261 if (!vma) 3262 break; 3263 if (vma->vm_ops && vma->vm_ops->access) 3264 ret = vma->vm_ops->access(vma, addr, buf, 3265 len, write); 3266 if (ret <= 0) 3267#endif 3268 break; 3269 bytes = ret; 3270 } else { 3271 bytes = len; 3272 offset = addr & (PAGE_SIZE-1); 3273 if (bytes > PAGE_SIZE-offset) 3274 bytes = PAGE_SIZE-offset; 3275 3276 maddr = kmap(page); 3277 if (write) { 3278 copy_to_user_page(vma, page, addr, 3279 maddr + offset, buf, bytes); 3280 set_page_dirty_lock(page); 3281 } else { 3282 copy_from_user_page(vma, page, addr, 3283 buf, maddr + offset, bytes); 3284 } 3285 kunmap(page); 3286 page_cache_release(page); 3287 } 3288 len -= bytes; 3289 buf += bytes; 3290 addr += bytes; 3291 } 3292 up_read(&mm->mmap_sem); 3293 mmput(mm); 3294 3295 return buf - old_buf; 3296} 3297 3298/* 3299 * Print the name of a VMA. 3300 */ 3301void print_vma_addr(char *prefix, unsigned long ip) 3302{ 3303 struct mm_struct *mm = current->mm; 3304 struct vm_area_struct *vma; 3305 3306 /* 3307 * Do not print if we are in atomic 3308 * contexts (in exception stacks, etc.): 3309 */ 3310 if (preempt_count()) 3311 return; 3312 3313 down_read(&mm->mmap_sem); 3314 vma = find_vma(mm, ip); 3315 if (vma && vma->vm_file) { 3316 struct file *f = vma->vm_file; 3317 char *buf = (char *)__get_free_page(GFP_KERNEL); 3318 if (buf) { 3319 char *p, *s; 3320 3321 p = d_path(&f->f_path, buf, PAGE_SIZE); 3322 if (IS_ERR(p)) 3323 p = "?"; 3324 s = strrchr(p, '/'); 3325 if (s) 3326 p = s+1; 3327 printk("%s%s[%lx+%lx]", prefix, p, 3328 vma->vm_start, 3329 vma->vm_end - vma->vm_start); 3330 free_page((unsigned long)buf); 3331 } 3332 } 3333 up_read(¤t->mm->mmap_sem); 3334} 3335 3336#ifdef CONFIG_PROVE_LOCKING 3337void might_fault(void) 3338{ 3339 /* 3340 * Some code (nfs/sunrpc) uses socket ops on kernel memory while 3341 * holding the mmap_sem, this is safe because kernel memory doesn't 3342 * get paged out, therefore we'll never actually fault, and the 3343 * below annotations will generate false positives. 3344 */ 3345 if (segment_eq(get_fs(), KERNEL_DS)) 3346 return; 3347 3348 might_sleep(); 3349 /* 3350 * it would be nicer only to annotate paths which are not under 3351 * pagefault_disable, however that requires a larger audit and 3352 * providing helpers like get_user_atomic. 3353 */ 3354 if (!in_atomic() && current->mm) 3355 might_lock_read(¤t->mm->mmap_sem); 3356} 3357EXPORT_SYMBOL(might_fault); 3358#endif 3359