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