1 /* 2 * mm/mmap.c 3 * 4 * Written by obz. 5 * 6 * Address space accounting code <alan@redhat.com> 7 */ 8 9 #include <linux/slab.h> 10 #include <linux/mm.h> 11 #include <linux/shm.h> 12 #include <linux/mman.h> 13 #include <linux/pagemap.h> 14 #include <linux/swap.h> 15 #include <linux/syscalls.h> 16 #include <linux/capability.h> 17 #include <linux/init.h> 18 #include <linux/file.h> 19 #include <linux/fs.h> 20 #include <linux/personality.h> 21 #include <linux/security.h> 22 #include <linux/hugetlb.h> 23 #include <linux/profile.h> 24 #include <linux/module.h> 25 #include <linux/mount.h> 26 #include <linux/mempolicy.h> 27 #include <linux/rmap.h> 28 29 #include <asm/uaccess.h> 30 #include <asm/cacheflush.h> 31 #include <asm/tlb.h> 32 #include <asm/mmu_context.h> 33 34 #ifndef arch_mmap_check 35 #define arch_mmap_check(addr, len, flags) (0) 36 #endif 37 38 static void unmap_region(struct mm_struct *mm, 39 struct vm_area_struct *vma, struct vm_area_struct *prev, 40 unsigned long start, unsigned long end); 41 42 /* 43 * WARNING: the debugging will use recursive algorithms so never enable this 44 * unless you know what you are doing. 45 */ 46 #undef DEBUG_MM_RB 47 48 /* description of effects of mapping type and prot in current implementation. 49 * this is due to the limited x86 page protection hardware. The expected 50 * behavior is in parens: 51 * 52 * map_type prot 53 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 54 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 55 * w: (no) no w: (no) no w: (yes) yes w: (no) no 56 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 57 * 58 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 59 * w: (no) no w: (no) no w: (copy) copy w: (no) no 60 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 61 * 62 */ 63 pgprot_t protection_map[16] = { 64 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 65 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 66 }; 67 68 pgprot_t vm_get_page_prot(unsigned long vm_flags) 69 { 70 return protection_map[vm_flags & 71 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; 72 } 73 EXPORT_SYMBOL(vm_get_page_prot); 74 75 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 76 int sysctl_overcommit_ratio = 50; /* default is 50% */ 77 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 78 atomic_t vm_committed_space = ATOMIC_INIT(0); 79 80 /* 81 * Check that a process has enough memory to allocate a new virtual 82 * mapping. 0 means there is enough memory for the allocation to 83 * succeed and -ENOMEM implies there is not. 84 * 85 * We currently support three overcommit policies, which are set via the 86 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 87 * 88 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 89 * Additional code 2002 Jul 20 by Robert Love. 90 * 91 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 92 * 93 * Note this is a helper function intended to be used by LSMs which 94 * wish to use this logic. 95 */ 96 int __vm_enough_memory(long pages, int cap_sys_admin) 97 { 98 unsigned long free, allowed; 99 100 vm_acct_memory(pages); 101 102 /* 103 * Sometimes we want to use more memory than we have 104 */ 105 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 106 return 0; 107 108 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 109 unsigned long n; 110 111 free = global_page_state(NR_FILE_PAGES); 112 free += nr_swap_pages; 113 114 /* 115 * Any slabs which are created with the 116 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 117 * which are reclaimable, under pressure. The dentry 118 * cache and most inode caches should fall into this 119 */ 120 free += global_page_state(NR_SLAB_RECLAIMABLE); 121 122 /* 123 * Leave the last 3% for root 124 */ 125 if (!cap_sys_admin) 126 free -= free / 32; 127 128 if (free > pages) 129 return 0; 130 131 /* 132 * nr_free_pages() is very expensive on large systems, 133 * only call if we're about to fail. 134 */ 135 n = nr_free_pages(); 136 137 /* 138 * Leave reserved pages. The pages are not for anonymous pages. 139 */ 140 if (n <= totalreserve_pages) 141 goto error; 142 else 143 n -= totalreserve_pages; 144 145 /* 146 * Leave the last 3% for root 147 */ 148 if (!cap_sys_admin) 149 n -= n / 32; 150 free += n; 151 152 if (free > pages) 153 return 0; 154 155 goto error; 156 } 157 158 allowed = (totalram_pages - hugetlb_total_pages()) 159 * sysctl_overcommit_ratio / 100; 160 /* 161 * Leave the last 3% for root 162 */ 163 if (!cap_sys_admin) 164 allowed -= allowed / 32; 165 allowed += total_swap_pages; 166 167 /* Don't let a single process grow too big: 168 leave 3% of the size of this process for other processes */ 169 allowed -= current->mm->total_vm / 32; 170 171 /* 172 * cast `allowed' as a signed long because vm_committed_space 173 * sometimes has a negative value 174 */ 175 if (atomic_read(&vm_committed_space) < (long)allowed) 176 return 0; 177 error: 178 vm_unacct_memory(pages); 179 180 return -ENOMEM; 181 } 182 183 EXPORT_SYMBOL(__vm_enough_memory); 184 185 /* 186 * Requires inode->i_mapping->i_mmap_lock 187 */ 188 static void __remove_shared_vm_struct(struct vm_area_struct *vma, 189 struct file *file, struct address_space *mapping) 190 { 191 if (vma->vm_flags & VM_DENYWRITE) 192 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 193 if (vma->vm_flags & VM_SHARED) 194 mapping->i_mmap_writable--; 195 196 flush_dcache_mmap_lock(mapping); 197 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 198 list_del_init(&vma->shared.vm_set.list); 199 else 200 vma_prio_tree_remove(vma, &mapping->i_mmap); 201 flush_dcache_mmap_unlock(mapping); 202 } 203 204 /* 205 * Unlink a file-based vm structure from its prio_tree, to hide 206 * vma from rmap and vmtruncate before freeing its page tables. 207 */ 208 void unlink_file_vma(struct vm_area_struct *vma) 209 { 210 struct file *file = vma->vm_file; 211 212 if (file) { 213 struct address_space *mapping = file->f_mapping; 214 spin_lock(&mapping->i_mmap_lock); 215 __remove_shared_vm_struct(vma, file, mapping); 216 spin_unlock(&mapping->i_mmap_lock); 217 } 218 } 219 220 /* 221 * Close a vm structure and free it, returning the next. 222 */ 223 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 224 { 225 struct vm_area_struct *next = vma->vm_next; 226 227 might_sleep(); 228 if (vma->vm_ops && vma->vm_ops->close) 229 vma->vm_ops->close(vma); 230 if (vma->vm_file) 231 fput(vma->vm_file); 232 mpol_free(vma_policy(vma)); 233 kmem_cache_free(vm_area_cachep, vma); 234 return next; 235 } 236 237 asmlinkage unsigned long sys_brk(unsigned long brk) 238 { 239 unsigned long rlim, retval; 240 unsigned long newbrk, oldbrk; 241 struct mm_struct *mm = current->mm; 242 243 down_write(&mm->mmap_sem); 244 245 if (brk < mm->end_code) 246 goto out; 247 248 /* 249 * Check against rlimit here. If this check is done later after the test 250 * of oldbrk with newbrk then it can escape the test and let the data 251 * segment grow beyond its set limit the in case where the limit is 252 * not page aligned -Ram Gupta 253 */ 254 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 255 if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) 256 goto out; 257 258 newbrk = PAGE_ALIGN(brk); 259 oldbrk = PAGE_ALIGN(mm->brk); 260 if (oldbrk == newbrk) 261 goto set_brk; 262 263 /* Always allow shrinking brk. */ 264 if (brk <= mm->brk) { 265 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 266 goto set_brk; 267 goto out; 268 } 269 270 /* Check against existing mmap mappings. */ 271 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 272 goto out; 273 274 /* Ok, looks good - let it rip. */ 275 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 276 goto out; 277 set_brk: 278 mm->brk = brk; 279 out: 280 retval = mm->brk; 281 up_write(&mm->mmap_sem); 282 return retval; 283 } 284 285 #ifdef DEBUG_MM_RB 286 static int browse_rb(struct rb_root *root) 287 { 288 int i = 0, j; 289 struct rb_node *nd, *pn = NULL; 290 unsigned long prev = 0, pend = 0; 291 292 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 293 struct vm_area_struct *vma; 294 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 295 if (vma->vm_start < prev) 296 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 297 if (vma->vm_start < pend) 298 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 299 if (vma->vm_start > vma->vm_end) 300 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 301 i++; 302 pn = nd; 303 prev = vma->vm_start; 304 pend = vma->vm_end; 305 } 306 j = 0; 307 for (nd = pn; nd; nd = rb_prev(nd)) { 308 j++; 309 } 310 if (i != j) 311 printk("backwards %d, forwards %d\n", j, i), i = 0; 312 return i; 313 } 314 315 void validate_mm(struct mm_struct *mm) 316 { 317 int bug = 0; 318 int i = 0; 319 struct vm_area_struct *tmp = mm->mmap; 320 while (tmp) { 321 tmp = tmp->vm_next; 322 i++; 323 } 324 if (i != mm->map_count) 325 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 326 i = browse_rb(&mm->mm_rb); 327 if (i != mm->map_count) 328 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 329 BUG_ON(bug); 330 } 331 #else 332 #define validate_mm(mm) do { } while (0) 333 #endif 334 335 static struct vm_area_struct * 336 find_vma_prepare(struct mm_struct *mm, unsigned long addr, 337 struct vm_area_struct **pprev, struct rb_node ***rb_link, 338 struct rb_node ** rb_parent) 339 { 340 struct vm_area_struct * vma; 341 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 342 343 __rb_link = &mm->mm_rb.rb_node; 344 rb_prev = __rb_parent = NULL; 345 vma = NULL; 346 347 while (*__rb_link) { 348 struct vm_area_struct *vma_tmp; 349 350 __rb_parent = *__rb_link; 351 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 352 353 if (vma_tmp->vm_end > addr) { 354 vma = vma_tmp; 355 if (vma_tmp->vm_start <= addr) 356 return vma; 357 __rb_link = &__rb_parent->rb_left; 358 } else { 359 rb_prev = __rb_parent; 360 __rb_link = &__rb_parent->rb_right; 361 } 362 } 363 364 *pprev = NULL; 365 if (rb_prev) 366 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 367 *rb_link = __rb_link; 368 *rb_parent = __rb_parent; 369 return vma; 370 } 371 372 static inline void 373 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 374 struct vm_area_struct *prev, struct rb_node *rb_parent) 375 { 376 if (prev) { 377 vma->vm_next = prev->vm_next; 378 prev->vm_next = vma; 379 } else { 380 mm->mmap = vma; 381 if (rb_parent) 382 vma->vm_next = rb_entry(rb_parent, 383 struct vm_area_struct, vm_rb); 384 else 385 vma->vm_next = NULL; 386 } 387 } 388 389 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 390 struct rb_node **rb_link, struct rb_node *rb_parent) 391 { 392 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 393 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 394 } 395 396 static inline void __vma_link_file(struct vm_area_struct *vma) 397 { 398 struct file * file; 399 400 file = vma->vm_file; 401 if (file) { 402 struct address_space *mapping = file->f_mapping; 403 404 if (vma->vm_flags & VM_DENYWRITE) 405 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 406 if (vma->vm_flags & VM_SHARED) 407 mapping->i_mmap_writable++; 408 409 flush_dcache_mmap_lock(mapping); 410 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 411 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 412 else 413 vma_prio_tree_insert(vma, &mapping->i_mmap); 414 flush_dcache_mmap_unlock(mapping); 415 } 416 } 417 418 static void 419 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 420 struct vm_area_struct *prev, struct rb_node **rb_link, 421 struct rb_node *rb_parent) 422 { 423 __vma_link_list(mm, vma, prev, rb_parent); 424 __vma_link_rb(mm, vma, rb_link, rb_parent); 425 __anon_vma_link(vma); 426 } 427 428 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 429 struct vm_area_struct *prev, struct rb_node **rb_link, 430 struct rb_node *rb_parent) 431 { 432 struct address_space *mapping = NULL; 433 434 if (vma->vm_file) 435 mapping = vma->vm_file->f_mapping; 436 437 if (mapping) { 438 spin_lock(&mapping->i_mmap_lock); 439 vma->vm_truncate_count = mapping->truncate_count; 440 } 441 anon_vma_lock(vma); 442 443 __vma_link(mm, vma, prev, rb_link, rb_parent); 444 __vma_link_file(vma); 445 446 anon_vma_unlock(vma); 447 if (mapping) 448 spin_unlock(&mapping->i_mmap_lock); 449 450 mm->map_count++; 451 validate_mm(mm); 452 } 453 454 /* 455 * Helper for vma_adjust in the split_vma insert case: 456 * insert vm structure into list and rbtree and anon_vma, 457 * but it has already been inserted into prio_tree earlier. 458 */ 459 static void 460 __insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 461 { 462 struct vm_area_struct * __vma, * prev; 463 struct rb_node ** rb_link, * rb_parent; 464 465 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 466 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 467 __vma_link(mm, vma, prev, rb_link, rb_parent); 468 mm->map_count++; 469 } 470 471 static inline void 472 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 473 struct vm_area_struct *prev) 474 { 475 prev->vm_next = vma->vm_next; 476 rb_erase(&vma->vm_rb, &mm->mm_rb); 477 if (mm->mmap_cache == vma) 478 mm->mmap_cache = prev; 479 } 480 481 /* 482 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 483 * is already present in an i_mmap tree without adjusting the tree. 484 * The following helper function should be used when such adjustments 485 * are necessary. The "insert" vma (if any) is to be inserted 486 * before we drop the necessary locks. 487 */ 488 void vma_adjust(struct vm_area_struct *vma, unsigned long start, 489 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 490 { 491 struct mm_struct *mm = vma->vm_mm; 492 struct vm_area_struct *next = vma->vm_next; 493 struct vm_area_struct *importer = NULL; 494 struct address_space *mapping = NULL; 495 struct prio_tree_root *root = NULL; 496 struct file *file = vma->vm_file; 497 struct anon_vma *anon_vma = NULL; 498 long adjust_next = 0; 499 int remove_next = 0; 500 501 if (next && !insert) { 502 if (end >= next->vm_end) { 503 /* 504 * vma expands, overlapping all the next, and 505 * perhaps the one after too (mprotect case 6). 506 */ 507 again: remove_next = 1 + (end > next->vm_end); 508 end = next->vm_end; 509 anon_vma = next->anon_vma; 510 importer = vma; 511 } else if (end > next->vm_start) { 512 /* 513 * vma expands, overlapping part of the next: 514 * mprotect case 5 shifting the boundary up. 515 */ 516 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 517 anon_vma = next->anon_vma; 518 importer = vma; 519 } else if (end < vma->vm_end) { 520 /* 521 * vma shrinks, and !insert tells it's not 522 * split_vma inserting another: so it must be 523 * mprotect case 4 shifting the boundary down. 524 */ 525 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 526 anon_vma = next->anon_vma; 527 importer = next; 528 } 529 } 530 531 if (file) { 532 mapping = file->f_mapping; 533 if (!(vma->vm_flags & VM_NONLINEAR)) 534 root = &mapping->i_mmap; 535 spin_lock(&mapping->i_mmap_lock); 536 if (importer && 537 vma->vm_truncate_count != next->vm_truncate_count) { 538 /* 539 * unmap_mapping_range might be in progress: 540 * ensure that the expanding vma is rescanned. 541 */ 542 importer->vm_truncate_count = 0; 543 } 544 if (insert) { 545 insert->vm_truncate_count = vma->vm_truncate_count; 546 /* 547 * Put into prio_tree now, so instantiated pages 548 * are visible to arm/parisc __flush_dcache_page 549 * throughout; but we cannot insert into address 550 * space until vma start or end is updated. 551 */ 552 __vma_link_file(insert); 553 } 554 } 555 556 /* 557 * When changing only vma->vm_end, we don't really need 558 * anon_vma lock: but is that case worth optimizing out? 559 */ 560 if (vma->anon_vma) 561 anon_vma = vma->anon_vma; 562 if (anon_vma) { 563 spin_lock(&anon_vma->lock); 564 /* 565 * Easily overlooked: when mprotect shifts the boundary, 566 * make sure the expanding vma has anon_vma set if the 567 * shrinking vma had, to cover any anon pages imported. 568 */ 569 if (importer && !importer->anon_vma) { 570 importer->anon_vma = anon_vma; 571 __anon_vma_link(importer); 572 } 573 } 574 575 if (root) { 576 flush_dcache_mmap_lock(mapping); 577 vma_prio_tree_remove(vma, root); 578 if (adjust_next) 579 vma_prio_tree_remove(next, root); 580 } 581 582 vma->vm_start = start; 583 vma->vm_end = end; 584 vma->vm_pgoff = pgoff; 585 if (adjust_next) { 586 next->vm_start += adjust_next << PAGE_SHIFT; 587 next->vm_pgoff += adjust_next; 588 } 589 590 if (root) { 591 if (adjust_next) 592 vma_prio_tree_insert(next, root); 593 vma_prio_tree_insert(vma, root); 594 flush_dcache_mmap_unlock(mapping); 595 } 596 597 if (remove_next) { 598 /* 599 * vma_merge has merged next into vma, and needs 600 * us to remove next before dropping the locks. 601 */ 602 __vma_unlink(mm, next, vma); 603 if (file) 604 __remove_shared_vm_struct(next, file, mapping); 605 if (next->anon_vma) 606 __anon_vma_merge(vma, next); 607 } else if (insert) { 608 /* 609 * split_vma has split insert from vma, and needs 610 * us to insert it before dropping the locks 611 * (it may either follow vma or precede it). 612 */ 613 __insert_vm_struct(mm, insert); 614 } 615 616 if (anon_vma) 617 spin_unlock(&anon_vma->lock); 618 if (mapping) 619 spin_unlock(&mapping->i_mmap_lock); 620 621 if (remove_next) { 622 if (file) 623 fput(file); 624 mm->map_count--; 625 mpol_free(vma_policy(next)); 626 kmem_cache_free(vm_area_cachep, next); 627 /* 628 * In mprotect's case 6 (see comments on vma_merge), 629 * we must remove another next too. It would clutter 630 * up the code too much to do both in one go. 631 */ 632 if (remove_next == 2) { 633 next = vma->vm_next; 634 goto again; 635 } 636 } 637 638 validate_mm(mm); 639 } 640 641 /* 642 * If the vma has a ->close operation then the driver probably needs to release 643 * per-vma resources, so we don't attempt to merge those. 644 */ 645 #define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) 646 647 static inline int is_mergeable_vma(struct vm_area_struct *vma, 648 struct file *file, unsigned long vm_flags) 649 { 650 if (vma->vm_flags != vm_flags) 651 return 0; 652 if (vma->vm_file != file) 653 return 0; 654 if (vma->vm_ops && vma->vm_ops->close) 655 return 0; 656 return 1; 657 } 658 659 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 660 struct anon_vma *anon_vma2) 661 { 662 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 663 } 664 665 /* 666 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 667 * in front of (at a lower virtual address and file offset than) the vma. 668 * 669 * We cannot merge two vmas if they have differently assigned (non-NULL) 670 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 671 * 672 * We don't check here for the merged mmap wrapping around the end of pagecache 673 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 674 * wrap, nor mmaps which cover the final page at index -1UL. 675 */ 676 static int 677 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 678 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 679 { 680 if (is_mergeable_vma(vma, file, vm_flags) && 681 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 682 if (vma->vm_pgoff == vm_pgoff) 683 return 1; 684 } 685 return 0; 686 } 687 688 /* 689 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 690 * beyond (at a higher virtual address and file offset than) the vma. 691 * 692 * We cannot merge two vmas if they have differently assigned (non-NULL) 693 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 694 */ 695 static int 696 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 697 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 698 { 699 if (is_mergeable_vma(vma, file, vm_flags) && 700 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 701 pgoff_t vm_pglen; 702 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 703 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 704 return 1; 705 } 706 return 0; 707 } 708 709 /* 710 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 711 * whether that can be merged with its predecessor or its successor. 712 * Or both (it neatly fills a hole). 713 * 714 * In most cases - when called for mmap, brk or mremap - [addr,end) is 715 * certain not to be mapped by the time vma_merge is called; but when 716 * called for mprotect, it is certain to be already mapped (either at 717 * an offset within prev, or at the start of next), and the flags of 718 * this area are about to be changed to vm_flags - and the no-change 719 * case has already been eliminated. 720 * 721 * The following mprotect cases have to be considered, where AAAA is 722 * the area passed down from mprotect_fixup, never extending beyond one 723 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 724 * 725 * AAAA AAAA AAAA AAAA 726 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 727 * cannot merge might become might become might become 728 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 729 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 730 * mremap move: PPPPNNNNNNNN 8 731 * AAAA 732 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 733 * might become case 1 below case 2 below case 3 below 734 * 735 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 736 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 737 */ 738 struct vm_area_struct *vma_merge(struct mm_struct *mm, 739 struct vm_area_struct *prev, unsigned long addr, 740 unsigned long end, unsigned long vm_flags, 741 struct anon_vma *anon_vma, struct file *file, 742 pgoff_t pgoff, struct mempolicy *policy) 743 { 744 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 745 struct vm_area_struct *area, *next; 746 747 /* 748 * We later require that vma->vm_flags == vm_flags, 749 * so this tests vma->vm_flags & VM_SPECIAL, too. 750 */ 751 if (vm_flags & VM_SPECIAL) 752 return NULL; 753 754 if (prev) 755 next = prev->vm_next; 756 else 757 next = mm->mmap; 758 area = next; 759 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 760 next = next->vm_next; 761 762 /* 763 * Can it merge with the predecessor? 764 */ 765 if (prev && prev->vm_end == addr && 766 mpol_equal(vma_policy(prev), policy) && 767 can_vma_merge_after(prev, vm_flags, 768 anon_vma, file, pgoff)) { 769 /* 770 * OK, it can. Can we now merge in the successor as well? 771 */ 772 if (next && end == next->vm_start && 773 mpol_equal(policy, vma_policy(next)) && 774 can_vma_merge_before(next, vm_flags, 775 anon_vma, file, pgoff+pglen) && 776 is_mergeable_anon_vma(prev->anon_vma, 777 next->anon_vma)) { 778 /* cases 1, 6 */ 779 vma_adjust(prev, prev->vm_start, 780 next->vm_end, prev->vm_pgoff, NULL); 781 } else /* cases 2, 5, 7 */ 782 vma_adjust(prev, prev->vm_start, 783 end, prev->vm_pgoff, NULL); 784 return prev; 785 } 786 787 /* 788 * Can this new request be merged in front of next? 789 */ 790 if (next && end == next->vm_start && 791 mpol_equal(policy, vma_policy(next)) && 792 can_vma_merge_before(next, vm_flags, 793 anon_vma, file, pgoff+pglen)) { 794 if (prev && addr < prev->vm_end) /* case 4 */ 795 vma_adjust(prev, prev->vm_start, 796 addr, prev->vm_pgoff, NULL); 797 else /* cases 3, 8 */ 798 vma_adjust(area, addr, next->vm_end, 799 next->vm_pgoff - pglen, NULL); 800 return area; 801 } 802 803 return NULL; 804 } 805 806 /* 807 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 808 * neighbouring vmas for a suitable anon_vma, before it goes off 809 * to allocate a new anon_vma. It checks because a repetitive 810 * sequence of mprotects and faults may otherwise lead to distinct 811 * anon_vmas being allocated, preventing vma merge in subsequent 812 * mprotect. 813 */ 814 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 815 { 816 struct vm_area_struct *near; 817 unsigned long vm_flags; 818 819 near = vma->vm_next; 820 if (!near) 821 goto try_prev; 822 823 /* 824 * Since only mprotect tries to remerge vmas, match flags 825 * which might be mprotected into each other later on. 826 * Neither mlock nor madvise tries to remerge at present, 827 * so leave their flags as obstructing a merge. 828 */ 829 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 830 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 831 832 if (near->anon_vma && vma->vm_end == near->vm_start && 833 mpol_equal(vma_policy(vma), vma_policy(near)) && 834 can_vma_merge_before(near, vm_flags, 835 NULL, vma->vm_file, vma->vm_pgoff + 836 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 837 return near->anon_vma; 838 try_prev: 839 /* 840 * It is potentially slow to have to call find_vma_prev here. 841 * But it's only on the first write fault on the vma, not 842 * every time, and we could devise a way to avoid it later 843 * (e.g. stash info in next's anon_vma_node when assigning 844 * an anon_vma, or when trying vma_merge). Another time. 845 */ 846 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 847 if (!near) 848 goto none; 849 850 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 851 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 852 853 if (near->anon_vma && near->vm_end == vma->vm_start && 854 mpol_equal(vma_policy(near), vma_policy(vma)) && 855 can_vma_merge_after(near, vm_flags, 856 NULL, vma->vm_file, vma->vm_pgoff)) 857 return near->anon_vma; 858 none: 859 /* 860 * There's no absolute need to look only at touching neighbours: 861 * we could search further afield for "compatible" anon_vmas. 862 * But it would probably just be a waste of time searching, 863 * or lead to too many vmas hanging off the same anon_vma. 864 * We're trying to allow mprotect remerging later on, 865 * not trying to minimize memory used for anon_vmas. 866 */ 867 return NULL; 868 } 869 870 #ifdef CONFIG_PROC_FS 871 void vm_stat_account(struct mm_struct *mm, unsigned long flags, 872 struct file *file, long pages) 873 { 874 const unsigned long stack_flags 875 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 876 877 if (file) { 878 mm->shared_vm += pages; 879 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 880 mm->exec_vm += pages; 881 } else if (flags & stack_flags) 882 mm->stack_vm += pages; 883 if (flags & (VM_RESERVED|VM_IO)) 884 mm->reserved_vm += pages; 885 } 886 #endif /* CONFIG_PROC_FS */ 887 888 /* 889 * The caller must hold down_write(current->mm->mmap_sem). 890 */ 891 892 unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 893 unsigned long len, unsigned long prot, 894 unsigned long flags, unsigned long pgoff) 895 { 896 struct mm_struct * mm = current->mm; 897 struct vm_area_struct * vma, * prev; 898 struct inode *inode; 899 unsigned int vm_flags; 900 int correct_wcount = 0; 901 int error; 902 struct rb_node ** rb_link, * rb_parent; 903 int accountable = 1; 904 unsigned long charged = 0, reqprot = prot; 905 906 /* 907 * Does the application expect PROT_READ to imply PROT_EXEC? 908 * 909 * (the exception is when the underlying filesystem is noexec 910 * mounted, in which case we dont add PROT_EXEC.) 911 */ 912 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 913 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 914 prot |= PROT_EXEC; 915 916 if (!len) 917 return -EINVAL; 918 919 error = arch_mmap_check(addr, len, flags); 920 if (error) 921 return error; 922 923 /* Careful about overflows.. */ 924 len = PAGE_ALIGN(len); 925 if (!len || len > TASK_SIZE) 926 return -ENOMEM; 927 928 /* offset overflow? */ 929 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 930 return -EOVERFLOW; 931 932 /* Too many mappings? */ 933 if (mm->map_count > sysctl_max_map_count) 934 return -ENOMEM; 935 936 /* Obtain the address to map to. we verify (or select) it and ensure 937 * that it represents a valid section of the address space. 938 */ 939 addr = get_unmapped_area(file, addr, len, pgoff, flags); 940 if (addr & ~PAGE_MASK) 941 return addr; 942 943 /* Do simple checking here so the lower-level routines won't have 944 * to. we assume access permissions have been handled by the open 945 * of the memory object, so we don't do any here. 946 */ 947 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 948 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 949 950 if (flags & MAP_LOCKED) { 951 if (!can_do_mlock()) 952 return -EPERM; 953 vm_flags |= VM_LOCKED; 954 } 955 /* mlock MCL_FUTURE? */ 956 if (vm_flags & VM_LOCKED) { 957 unsigned long locked, lock_limit; 958 locked = len >> PAGE_SHIFT; 959 locked += mm->locked_vm; 960 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 961 lock_limit >>= PAGE_SHIFT; 962 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 963 return -EAGAIN; 964 } 965 966 inode = file ? file->f_path.dentry->d_inode : NULL; 967 968 if (file) { 969 switch (flags & MAP_TYPE) { 970 case MAP_SHARED: 971 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 972 return -EACCES; 973 974 /* 975 * Make sure we don't allow writing to an append-only 976 * file.. 977 */ 978 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 979 return -EACCES; 980 981 /* 982 * Make sure there are no mandatory locks on the file. 983 */ 984 if (locks_verify_locked(inode)) 985 return -EAGAIN; 986 987 vm_flags |= VM_SHARED | VM_MAYSHARE; 988 if (!(file->f_mode & FMODE_WRITE)) 989 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 990 991 /* fall through */ 992 case MAP_PRIVATE: 993 if (!(file->f_mode & FMODE_READ)) 994 return -EACCES; 995 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 996 if (vm_flags & VM_EXEC) 997 return -EPERM; 998 vm_flags &= ~VM_MAYEXEC; 999 } 1000 if (is_file_hugepages(file)) 1001 accountable = 0; 1002 1003 if (!file->f_op || !file->f_op->mmap) 1004 return -ENODEV; 1005 break; 1006 1007 default: 1008 return -EINVAL; 1009 } 1010 } else { 1011 switch (flags & MAP_TYPE) { 1012 case MAP_SHARED: 1013 vm_flags |= VM_SHARED | VM_MAYSHARE; 1014 break; 1015 case MAP_PRIVATE: 1016 /* 1017 * Set pgoff according to addr for anon_vma. 1018 */ 1019 pgoff = addr >> PAGE_SHIFT; 1020 break; 1021 default: 1022 return -EINVAL; 1023 } 1024 } 1025 1026 error = security_file_mmap(file, reqprot, prot, flags); 1027 if (error) 1028 return error; 1029 1030 /* Clear old maps */ 1031 error = -ENOMEM; 1032 munmap_back: 1033 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1034 if (vma && vma->vm_start < addr + len) { 1035 if (do_munmap(mm, addr, len)) 1036 return -ENOMEM; 1037 goto munmap_back; 1038 } 1039 1040 /* Check against address space limit. */ 1041 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1042 return -ENOMEM; 1043 1044 if (accountable && (!(flags & MAP_NORESERVE) || 1045 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { 1046 if (vm_flags & VM_SHARED) { 1047 /* Check memory availability in shmem_file_setup? */ 1048 vm_flags |= VM_ACCOUNT; 1049 } else if (vm_flags & VM_WRITE) { 1050 /* 1051 * Private writable mapping: check memory availability 1052 */ 1053 charged = len >> PAGE_SHIFT; 1054 if (security_vm_enough_memory(charged)) 1055 return -ENOMEM; 1056 vm_flags |= VM_ACCOUNT; 1057 } 1058 } 1059 1060 /* 1061 * Can we just expand an old private anonymous mapping? 1062 * The VM_SHARED test is necessary because shmem_zero_setup 1063 * will create the file object for a shared anonymous map below. 1064 */ 1065 if (!file && !(vm_flags & VM_SHARED) && 1066 vma_merge(mm, prev, addr, addr + len, vm_flags, 1067 NULL, NULL, pgoff, NULL)) 1068 goto out; 1069 1070 /* 1071 * Determine the object being mapped and call the appropriate 1072 * specific mapper. the address has already been validated, but 1073 * not unmapped, but the maps are removed from the list. 1074 */ 1075 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1076 if (!vma) { 1077 error = -ENOMEM; 1078 goto unacct_error; 1079 } 1080 1081 vma->vm_mm = mm; 1082 vma->vm_start = addr; 1083 vma->vm_end = addr + len; 1084 vma->vm_flags = vm_flags; 1085 vma->vm_page_prot = protection_map[vm_flags & 1086 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; 1087 vma->vm_pgoff = pgoff; 1088 1089 if (file) { 1090 error = -EINVAL; 1091 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1092 goto free_vma; 1093 if (vm_flags & VM_DENYWRITE) { 1094 error = deny_write_access(file); 1095 if (error) 1096 goto free_vma; 1097 correct_wcount = 1; 1098 } 1099 vma->vm_file = file; 1100 get_file(file); 1101 error = file->f_op->mmap(file, vma); 1102 if (error) 1103 goto unmap_and_free_vma; 1104 } else if (vm_flags & VM_SHARED) { 1105 error = shmem_zero_setup(vma); 1106 if (error) 1107 goto free_vma; 1108 } 1109 1110 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1111 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1112 * that memory reservation must be checked; but that reservation 1113 * belongs to shared memory object, not to vma: so now clear it. 1114 */ 1115 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1116 vma->vm_flags &= ~VM_ACCOUNT; 1117 1118 /* Can addr have changed?? 1119 * 1120 * Answer: Yes, several device drivers can do it in their 1121 * f_op->mmap method. -DaveM 1122 */ 1123 addr = vma->vm_start; 1124 pgoff = vma->vm_pgoff; 1125 vm_flags = vma->vm_flags; 1126 1127 if (vma_wants_writenotify(vma)) 1128 vma->vm_page_prot = 1129 protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC)]; 1130 1131 if (!file || !vma_merge(mm, prev, addr, vma->vm_end, 1132 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1133 file = vma->vm_file; 1134 vma_link(mm, vma, prev, rb_link, rb_parent); 1135 if (correct_wcount) 1136 atomic_inc(&inode->i_writecount); 1137 } else { 1138 if (file) { 1139 if (correct_wcount) 1140 atomic_inc(&inode->i_writecount); 1141 fput(file); 1142 } 1143 mpol_free(vma_policy(vma)); 1144 kmem_cache_free(vm_area_cachep, vma); 1145 } 1146 out: 1147 mm->total_vm += len >> PAGE_SHIFT; 1148 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1149 if (vm_flags & VM_LOCKED) { 1150 mm->locked_vm += len >> PAGE_SHIFT; 1151 make_pages_present(addr, addr + len); 1152 } 1153 if (flags & MAP_POPULATE) { 1154 up_write(&mm->mmap_sem); 1155 sys_remap_file_pages(addr, len, 0, 1156 pgoff, flags & MAP_NONBLOCK); 1157 down_write(&mm->mmap_sem); 1158 } 1159 return addr; 1160 1161 unmap_and_free_vma: 1162 if (correct_wcount) 1163 atomic_inc(&inode->i_writecount); 1164 vma->vm_file = NULL; 1165 fput(file); 1166 1167 /* Undo any partial mapping done by a device driver. */ 1168 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1169 charged = 0; 1170 free_vma: 1171 kmem_cache_free(vm_area_cachep, vma); 1172 unacct_error: 1173 if (charged) 1174 vm_unacct_memory(charged); 1175 return error; 1176 } 1177 1178 EXPORT_SYMBOL(do_mmap_pgoff); 1179 1180 /* Get an address range which is currently unmapped. 1181 * For shmat() with addr=0. 1182 * 1183 * Ugly calling convention alert: 1184 * Return value with the low bits set means error value, 1185 * ie 1186 * if (ret & ~PAGE_MASK) 1187 * error = ret; 1188 * 1189 * This function "knows" that -ENOMEM has the bits set. 1190 */ 1191 #ifndef HAVE_ARCH_UNMAPPED_AREA 1192 unsigned long 1193 arch_get_unmapped_area(struct file *filp, unsigned long addr, 1194 unsigned long len, unsigned long pgoff, unsigned long flags) 1195 { 1196 struct mm_struct *mm = current->mm; 1197 struct vm_area_struct *vma; 1198 unsigned long start_addr; 1199 1200 if (len > TASK_SIZE) 1201 return -ENOMEM; 1202 1203 if (flags & MAP_FIXED) 1204 return addr; 1205 1206 if (addr) { 1207 addr = PAGE_ALIGN(addr); 1208 vma = find_vma(mm, addr); 1209 if (TASK_SIZE - len >= addr && 1210 (!vma || addr + len <= vma->vm_start)) 1211 return addr; 1212 } 1213 if (len > mm->cached_hole_size) { 1214 start_addr = addr = mm->free_area_cache; 1215 } else { 1216 start_addr = addr = TASK_UNMAPPED_BASE; 1217 mm->cached_hole_size = 0; 1218 } 1219 1220 full_search: 1221 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1222 /* At this point: (!vma || addr < vma->vm_end). */ 1223 if (TASK_SIZE - len < addr) { 1224 /* 1225 * Start a new search - just in case we missed 1226 * some holes. 1227 */ 1228 if (start_addr != TASK_UNMAPPED_BASE) { 1229 addr = TASK_UNMAPPED_BASE; 1230 start_addr = addr; 1231 mm->cached_hole_size = 0; 1232 goto full_search; 1233 } 1234 return -ENOMEM; 1235 } 1236 if (!vma || addr + len <= vma->vm_start) { 1237 /* 1238 * Remember the place where we stopped the search: 1239 */ 1240 mm->free_area_cache = addr + len; 1241 return addr; 1242 } 1243 if (addr + mm->cached_hole_size < vma->vm_start) 1244 mm->cached_hole_size = vma->vm_start - addr; 1245 addr = vma->vm_end; 1246 } 1247 } 1248 #endif 1249 1250 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1251 { 1252 /* 1253 * Is this a new hole at the lowest possible address? 1254 */ 1255 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1256 mm->free_area_cache = addr; 1257 mm->cached_hole_size = ~0UL; 1258 } 1259 } 1260 1261 /* 1262 * This mmap-allocator allocates new areas top-down from below the 1263 * stack's low limit (the base): 1264 */ 1265 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1266 unsigned long 1267 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1268 const unsigned long len, const unsigned long pgoff, 1269 const unsigned long flags) 1270 { 1271 struct vm_area_struct *vma; 1272 struct mm_struct *mm = current->mm; 1273 unsigned long addr = addr0; 1274 1275 /* requested length too big for entire address space */ 1276 if (len > TASK_SIZE) 1277 return -ENOMEM; 1278 1279 if (flags & MAP_FIXED) 1280 return addr; 1281 1282 /* requesting a specific address */ 1283 if (addr) { 1284 addr = PAGE_ALIGN(addr); 1285 vma = find_vma(mm, addr); 1286 if (TASK_SIZE - len >= addr && 1287 (!vma || addr + len <= vma->vm_start)) 1288 return addr; 1289 } 1290 1291 /* check if free_area_cache is useful for us */ 1292 if (len <= mm->cached_hole_size) { 1293 mm->cached_hole_size = 0; 1294 mm->free_area_cache = mm->mmap_base; 1295 } 1296 1297 /* either no address requested or can't fit in requested address hole */ 1298 addr = mm->free_area_cache; 1299 1300 /* make sure it can fit in the remaining address space */ 1301 if (addr > len) { 1302 vma = find_vma(mm, addr-len); 1303 if (!vma || addr <= vma->vm_start) 1304 /* remember the address as a hint for next time */ 1305 return (mm->free_area_cache = addr-len); 1306 } 1307 1308 if (mm->mmap_base < len) 1309 goto bottomup; 1310 1311 addr = mm->mmap_base-len; 1312 1313 do { 1314 /* 1315 * Lookup failure means no vma is above this address, 1316 * else if new region fits below vma->vm_start, 1317 * return with success: 1318 */ 1319 vma = find_vma(mm, addr); 1320 if (!vma || addr+len <= vma->vm_start) 1321 /* remember the address as a hint for next time */ 1322 return (mm->free_area_cache = addr); 1323 1324 /* remember the largest hole we saw so far */ 1325 if (addr + mm->cached_hole_size < vma->vm_start) 1326 mm->cached_hole_size = vma->vm_start - addr; 1327 1328 /* try just below the current vma->vm_start */ 1329 addr = vma->vm_start-len; 1330 } while (len < vma->vm_start); 1331 1332 bottomup: 1333 /* 1334 * A failed mmap() very likely causes application failure, 1335 * so fall back to the bottom-up function here. This scenario 1336 * can happen with large stack limits and large mmap() 1337 * allocations. 1338 */ 1339 mm->cached_hole_size = ~0UL; 1340 mm->free_area_cache = TASK_UNMAPPED_BASE; 1341 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1342 /* 1343 * Restore the topdown base: 1344 */ 1345 mm->free_area_cache = mm->mmap_base; 1346 mm->cached_hole_size = ~0UL; 1347 1348 return addr; 1349 } 1350 #endif 1351 1352 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1353 { 1354 /* 1355 * Is this a new hole at the highest possible address? 1356 */ 1357 if (addr > mm->free_area_cache) 1358 mm->free_area_cache = addr; 1359 1360 /* dont allow allocations above current base */ 1361 if (mm->free_area_cache > mm->mmap_base) 1362 mm->free_area_cache = mm->mmap_base; 1363 } 1364 1365 unsigned long 1366 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1367 unsigned long pgoff, unsigned long flags) 1368 { 1369 unsigned long (*get_area)(struct file *, unsigned long, 1370 unsigned long, unsigned long, unsigned long); 1371 1372 get_area = current->mm->get_unmapped_area; 1373 if (file && file->f_op && file->f_op->get_unmapped_area) 1374 get_area = file->f_op->get_unmapped_area; 1375 addr = get_area(file, addr, len, pgoff, flags); 1376 if (IS_ERR_VALUE(addr)) 1377 return addr; 1378 1379 if (addr > TASK_SIZE - len) 1380 return -ENOMEM; 1381 if (addr & ~PAGE_MASK) 1382 return -EINVAL; 1383 1384 return addr; 1385 } 1386 1387 EXPORT_SYMBOL(get_unmapped_area); 1388 1389 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1390 struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1391 { 1392 struct vm_area_struct *vma = NULL; 1393 1394 if (mm) { 1395 /* Check the cache first. */ 1396 /* (Cache hit rate is typically around 35%.) */ 1397 vma = mm->mmap_cache; 1398 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1399 struct rb_node * rb_node; 1400 1401 rb_node = mm->mm_rb.rb_node; 1402 vma = NULL; 1403 1404 while (rb_node) { 1405 struct vm_area_struct * vma_tmp; 1406 1407 vma_tmp = rb_entry(rb_node, 1408 struct vm_area_struct, vm_rb); 1409 1410 if (vma_tmp->vm_end > addr) { 1411 vma = vma_tmp; 1412 if (vma_tmp->vm_start <= addr) 1413 break; 1414 rb_node = rb_node->rb_left; 1415 } else 1416 rb_node = rb_node->rb_right; 1417 } 1418 if (vma) 1419 mm->mmap_cache = vma; 1420 } 1421 } 1422 return vma; 1423 } 1424 1425 EXPORT_SYMBOL(find_vma); 1426 1427 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1428 struct vm_area_struct * 1429 find_vma_prev(struct mm_struct *mm, unsigned long addr, 1430 struct vm_area_struct **pprev) 1431 { 1432 struct vm_area_struct *vma = NULL, *prev = NULL; 1433 struct rb_node * rb_node; 1434 if (!mm) 1435 goto out; 1436 1437 /* Guard against addr being lower than the first VMA */ 1438 vma = mm->mmap; 1439 1440 /* Go through the RB tree quickly. */ 1441 rb_node = mm->mm_rb.rb_node; 1442 1443 while (rb_node) { 1444 struct vm_area_struct *vma_tmp; 1445 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1446 1447 if (addr < vma_tmp->vm_end) { 1448 rb_node = rb_node->rb_left; 1449 } else { 1450 prev = vma_tmp; 1451 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1452 break; 1453 rb_node = rb_node->rb_right; 1454 } 1455 } 1456 1457 out: 1458 *pprev = prev; 1459 return prev ? prev->vm_next : vma; 1460 } 1461 1462 /* 1463 * Verify that the stack growth is acceptable and 1464 * update accounting. This is shared with both the 1465 * grow-up and grow-down cases. 1466 */ 1467 static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1468 { 1469 struct mm_struct *mm = vma->vm_mm; 1470 struct rlimit *rlim = current->signal->rlim; 1471 unsigned long new_start; 1472 1473 /* address space limit tests */ 1474 if (!may_expand_vm(mm, grow)) 1475 return -ENOMEM; 1476 1477 /* Stack limit test */ 1478 if (size > rlim[RLIMIT_STACK].rlim_cur) 1479 return -ENOMEM; 1480 1481 /* mlock limit tests */ 1482 if (vma->vm_flags & VM_LOCKED) { 1483 unsigned long locked; 1484 unsigned long limit; 1485 locked = mm->locked_vm + grow; 1486 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1487 if (locked > limit && !capable(CAP_IPC_LOCK)) 1488 return -ENOMEM; 1489 } 1490 1491 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1492 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1493 vma->vm_end - size; 1494 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1495 return -EFAULT; 1496 1497 /* 1498 * Overcommit.. This must be the final test, as it will 1499 * update security statistics. 1500 */ 1501 if (security_vm_enough_memory(grow)) 1502 return -ENOMEM; 1503 1504 /* Ok, everything looks good - let it rip */ 1505 mm->total_vm += grow; 1506 if (vma->vm_flags & VM_LOCKED) 1507 mm->locked_vm += grow; 1508 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1509 return 0; 1510 } 1511 1512 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1513 /* 1514 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1515 * vma is the last one with address > vma->vm_end. Have to extend vma. 1516 */ 1517 #ifndef CONFIG_IA64 1518 static inline 1519 #endif 1520 int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1521 { 1522 int error; 1523 1524 if (!(vma->vm_flags & VM_GROWSUP)) 1525 return -EFAULT; 1526 1527 /* 1528 * We must make sure the anon_vma is allocated 1529 * so that the anon_vma locking is not a noop. 1530 */ 1531 if (unlikely(anon_vma_prepare(vma))) 1532 return -ENOMEM; 1533 anon_vma_lock(vma); 1534 1535 /* 1536 * vma->vm_start/vm_end cannot change under us because the caller 1537 * is required to hold the mmap_sem in read mode. We need the 1538 * anon_vma lock to serialize against concurrent expand_stacks. 1539 */ 1540 address += 4 + PAGE_SIZE - 1; 1541 address &= PAGE_MASK; 1542 error = 0; 1543 1544 /* Somebody else might have raced and expanded it already */ 1545 if (address > vma->vm_end) { 1546 unsigned long size, grow; 1547 1548 size = address - vma->vm_start; 1549 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1550 1551 error = acct_stack_growth(vma, size, grow); 1552 if (!error) 1553 vma->vm_end = address; 1554 } 1555 anon_vma_unlock(vma); 1556 return error; 1557 } 1558 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1559 1560 #ifdef CONFIG_STACK_GROWSUP 1561 int expand_stack(struct vm_area_struct *vma, unsigned long address) 1562 { 1563 return expand_upwards(vma, address); 1564 } 1565 1566 struct vm_area_struct * 1567 find_extend_vma(struct mm_struct *mm, unsigned long addr) 1568 { 1569 struct vm_area_struct *vma, *prev; 1570 1571 addr &= PAGE_MASK; 1572 vma = find_vma_prev(mm, addr, &prev); 1573 if (vma && (vma->vm_start <= addr)) 1574 return vma; 1575 if (!prev || expand_stack(prev, addr)) 1576 return NULL; 1577 if (prev->vm_flags & VM_LOCKED) { 1578 make_pages_present(addr, prev->vm_end); 1579 } 1580 return prev; 1581 } 1582 #else 1583 /* 1584 * vma is the first one with address < vma->vm_start. Have to extend vma. 1585 */ 1586 int expand_stack(struct vm_area_struct *vma, unsigned long address) 1587 { 1588 int error; 1589 1590 /* 1591 * We must make sure the anon_vma is allocated 1592 * so that the anon_vma locking is not a noop. 1593 */ 1594 if (unlikely(anon_vma_prepare(vma))) 1595 return -ENOMEM; 1596 anon_vma_lock(vma); 1597 1598 /* 1599 * vma->vm_start/vm_end cannot change under us because the caller 1600 * is required to hold the mmap_sem in read mode. We need the 1601 * anon_vma lock to serialize against concurrent expand_stacks. 1602 */ 1603 address &= PAGE_MASK; 1604 error = 0; 1605 1606 /* Somebody else might have raced and expanded it already */ 1607 if (address < vma->vm_start) { 1608 unsigned long size, grow; 1609 1610 size = vma->vm_end - address; 1611 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1612 1613 error = acct_stack_growth(vma, size, grow); 1614 if (!error) { 1615 vma->vm_start = address; 1616 vma->vm_pgoff -= grow; 1617 } 1618 } 1619 anon_vma_unlock(vma); 1620 return error; 1621 } 1622 1623 struct vm_area_struct * 1624 find_extend_vma(struct mm_struct * mm, unsigned long addr) 1625 { 1626 struct vm_area_struct * vma; 1627 unsigned long start; 1628 1629 addr &= PAGE_MASK; 1630 vma = find_vma(mm,addr); 1631 if (!vma) 1632 return NULL; 1633 if (vma->vm_start <= addr) 1634 return vma; 1635 if (!(vma->vm_flags & VM_GROWSDOWN)) 1636 return NULL; 1637 start = vma->vm_start; 1638 if (expand_stack(vma, addr)) 1639 return NULL; 1640 if (vma->vm_flags & VM_LOCKED) { 1641 make_pages_present(addr, start); 1642 } 1643 return vma; 1644 } 1645 #endif 1646 1647 /* 1648 * Ok - we have the memory areas we should free on the vma list, 1649 * so release them, and do the vma updates. 1650 * 1651 * Called with the mm semaphore held. 1652 */ 1653 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1654 { 1655 /* Update high watermark before we lower total_vm */ 1656 update_hiwater_vm(mm); 1657 do { 1658 long nrpages = vma_pages(vma); 1659 1660 mm->total_vm -= nrpages; 1661 if (vma->vm_flags & VM_LOCKED) 1662 mm->locked_vm -= nrpages; 1663 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1664 vma = remove_vma(vma); 1665 } while (vma); 1666 validate_mm(mm); 1667 } 1668 1669 /* 1670 * Get rid of page table information in the indicated region. 1671 * 1672 * Called with the mm semaphore held. 1673 */ 1674 static void unmap_region(struct mm_struct *mm, 1675 struct vm_area_struct *vma, struct vm_area_struct *prev, 1676 unsigned long start, unsigned long end) 1677 { 1678 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1679 struct mmu_gather *tlb; 1680 unsigned long nr_accounted = 0; 1681 1682 lru_add_drain(); 1683 tlb = tlb_gather_mmu(mm, 0); 1684 update_hiwater_rss(mm); 1685 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1686 vm_unacct_memory(nr_accounted); 1687 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1688 next? next->vm_start: 0); 1689 tlb_finish_mmu(tlb, start, end); 1690 } 1691 1692 /* 1693 * Create a list of vma's touched by the unmap, removing them from the mm's 1694 * vma list as we go.. 1695 */ 1696 static void 1697 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1698 struct vm_area_struct *prev, unsigned long end) 1699 { 1700 struct vm_area_struct **insertion_point; 1701 struct vm_area_struct *tail_vma = NULL; 1702 unsigned long addr; 1703 1704 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1705 do { 1706 rb_erase(&vma->vm_rb, &mm->mm_rb); 1707 mm->map_count--; 1708 tail_vma = vma; 1709 vma = vma->vm_next; 1710 } while (vma && vma->vm_start < end); 1711 *insertion_point = vma; 1712 tail_vma->vm_next = NULL; 1713 if (mm->unmap_area == arch_unmap_area) 1714 addr = prev ? prev->vm_end : mm->mmap_base; 1715 else 1716 addr = vma ? vma->vm_start : mm->mmap_base; 1717 mm->unmap_area(mm, addr); 1718 mm->mmap_cache = NULL; /* Kill the cache. */ 1719 } 1720 1721 /* 1722 * Split a vma into two pieces at address 'addr', a new vma is allocated 1723 * either for the first part or the tail. 1724 */ 1725 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1726 unsigned long addr, int new_below) 1727 { 1728 struct mempolicy *pol; 1729 struct vm_area_struct *new; 1730 1731 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK)) 1732 return -EINVAL; 1733 1734 if (mm->map_count >= sysctl_max_map_count) 1735 return -ENOMEM; 1736 1737 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1738 if (!new) 1739 return -ENOMEM; 1740 1741 /* most fields are the same, copy all, and then fixup */ 1742 *new = *vma; 1743 1744 if (new_below) 1745 new->vm_end = addr; 1746 else { 1747 new->vm_start = addr; 1748 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1749 } 1750 1751 pol = mpol_copy(vma_policy(vma)); 1752 if (IS_ERR(pol)) { 1753 kmem_cache_free(vm_area_cachep, new); 1754 return PTR_ERR(pol); 1755 } 1756 vma_set_policy(new, pol); 1757 1758 if (new->vm_file) 1759 get_file(new->vm_file); 1760 1761 if (new->vm_ops && new->vm_ops->open) 1762 new->vm_ops->open(new); 1763 1764 if (new_below) 1765 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1766 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1767 else 1768 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1769 1770 return 0; 1771 } 1772 1773 /* Munmap is split into 2 main parts -- this part which finds 1774 * what needs doing, and the areas themselves, which do the 1775 * work. This now handles partial unmappings. 1776 * Jeremy Fitzhardinge <jeremy@goop.org> 1777 */ 1778 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1779 { 1780 unsigned long end; 1781 struct vm_area_struct *vma, *prev, *last; 1782 1783 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1784 return -EINVAL; 1785 1786 if ((len = PAGE_ALIGN(len)) == 0) 1787 return -EINVAL; 1788 1789 /* Find the first overlapping VMA */ 1790 vma = find_vma_prev(mm, start, &prev); 1791 if (!vma) 1792 return 0; 1793 /* we have start < vma->vm_end */ 1794 1795 /* if it doesn't overlap, we have nothing.. */ 1796 end = start + len; 1797 if (vma->vm_start >= end) 1798 return 0; 1799 1800 /* 1801 * If we need to split any vma, do it now to save pain later. 1802 * 1803 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1804 * unmapped vm_area_struct will remain in use: so lower split_vma 1805 * places tmp vma above, and higher split_vma places tmp vma below. 1806 */ 1807 if (start > vma->vm_start) { 1808 int error = split_vma(mm, vma, start, 0); 1809 if (error) 1810 return error; 1811 prev = vma; 1812 } 1813 1814 /* Does it split the last one? */ 1815 last = find_vma(mm, end); 1816 if (last && end > last->vm_start) { 1817 int error = split_vma(mm, last, end, 1); 1818 if (error) 1819 return error; 1820 } 1821 vma = prev? prev->vm_next: mm->mmap; 1822 1823 /* 1824 * Remove the vma's, and unmap the actual pages 1825 */ 1826 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1827 unmap_region(mm, vma, prev, start, end); 1828 1829 /* Fix up all other VM information */ 1830 remove_vma_list(mm, vma); 1831 1832 return 0; 1833 } 1834 1835 EXPORT_SYMBOL(do_munmap); 1836 1837 asmlinkage long sys_munmap(unsigned long addr, size_t len) 1838 { 1839 int ret; 1840 struct mm_struct *mm = current->mm; 1841 1842 profile_munmap(addr); 1843 1844 down_write(&mm->mmap_sem); 1845 ret = do_munmap(mm, addr, len); 1846 up_write(&mm->mmap_sem); 1847 return ret; 1848 } 1849 1850 static inline void verify_mm_writelocked(struct mm_struct *mm) 1851 { 1852 #ifdef CONFIG_DEBUG_VM 1853 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1854 WARN_ON(1); 1855 up_read(&mm->mmap_sem); 1856 } 1857 #endif 1858 } 1859 1860 /* 1861 * this is really a simplified "do_mmap". it only handles 1862 * anonymous maps. eventually we may be able to do some 1863 * brk-specific accounting here. 1864 */ 1865 unsigned long do_brk(unsigned long addr, unsigned long len) 1866 { 1867 struct mm_struct * mm = current->mm; 1868 struct vm_area_struct * vma, * prev; 1869 unsigned long flags; 1870 struct rb_node ** rb_link, * rb_parent; 1871 pgoff_t pgoff = addr >> PAGE_SHIFT; 1872 int error; 1873 1874 len = PAGE_ALIGN(len); 1875 if (!len) 1876 return addr; 1877 1878 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1879 return -EINVAL; 1880 1881 if (is_hugepage_only_range(mm, addr, len)) 1882 return -EINVAL; 1883 1884 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1885 1886 error = arch_mmap_check(addr, len, flags); 1887 if (error) 1888 return error; 1889 1890 /* 1891 * mlock MCL_FUTURE? 1892 */ 1893 if (mm->def_flags & VM_LOCKED) { 1894 unsigned long locked, lock_limit; 1895 locked = len >> PAGE_SHIFT; 1896 locked += mm->locked_vm; 1897 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1898 lock_limit >>= PAGE_SHIFT; 1899 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1900 return -EAGAIN; 1901 } 1902 1903 /* 1904 * mm->mmap_sem is required to protect against another thread 1905 * changing the mappings in case we sleep. 1906 */ 1907 verify_mm_writelocked(mm); 1908 1909 /* 1910 * Clear old maps. this also does some error checking for us 1911 */ 1912 munmap_back: 1913 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1914 if (vma && vma->vm_start < addr + len) { 1915 if (do_munmap(mm, addr, len)) 1916 return -ENOMEM; 1917 goto munmap_back; 1918 } 1919 1920 /* Check against address space limits *after* clearing old maps... */ 1921 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1922 return -ENOMEM; 1923 1924 if (mm->map_count > sysctl_max_map_count) 1925 return -ENOMEM; 1926 1927 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 1928 return -ENOMEM; 1929 1930 /* Can we just expand an old private anonymous mapping? */ 1931 if (vma_merge(mm, prev, addr, addr + len, flags, 1932 NULL, NULL, pgoff, NULL)) 1933 goto out; 1934 1935 /* 1936 * create a vma struct for an anonymous mapping 1937 */ 1938 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1939 if (!vma) { 1940 vm_unacct_memory(len >> PAGE_SHIFT); 1941 return -ENOMEM; 1942 } 1943 1944 vma->vm_mm = mm; 1945 vma->vm_start = addr; 1946 vma->vm_end = addr + len; 1947 vma->vm_pgoff = pgoff; 1948 vma->vm_flags = flags; 1949 vma->vm_page_prot = protection_map[flags & 1950 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; 1951 vma_link(mm, vma, prev, rb_link, rb_parent); 1952 out: 1953 mm->total_vm += len >> PAGE_SHIFT; 1954 if (flags & VM_LOCKED) { 1955 mm->locked_vm += len >> PAGE_SHIFT; 1956 make_pages_present(addr, addr + len); 1957 } 1958 return addr; 1959 } 1960 1961 EXPORT_SYMBOL(do_brk); 1962 1963 /* Release all mmaps. */ 1964 void exit_mmap(struct mm_struct *mm) 1965 { 1966 struct mmu_gather *tlb; 1967 struct vm_area_struct *vma = mm->mmap; 1968 unsigned long nr_accounted = 0; 1969 unsigned long end; 1970 1971 /* mm's last user has gone, and its about to be pulled down */ 1972 arch_exit_mmap(mm); 1973 1974 lru_add_drain(); 1975 flush_cache_mm(mm); 1976 tlb = tlb_gather_mmu(mm, 1); 1977 /* Don't update_hiwater_rss(mm) here, do_exit already did */ 1978 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 1979 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 1980 vm_unacct_memory(nr_accounted); 1981 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); 1982 tlb_finish_mmu(tlb, 0, end); 1983 1984 /* 1985 * Walk the list again, actually closing and freeing it, 1986 * with preemption enabled, without holding any MM locks. 1987 */ 1988 while (vma) 1989 vma = remove_vma(vma); 1990 1991 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 1992 } 1993 1994 /* Insert vm structure into process list sorted by address 1995 * and into the inode's i_mmap tree. If vm_file is non-NULL 1996 * then i_mmap_lock is taken here. 1997 */ 1998 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 1999 { 2000 struct vm_area_struct * __vma, * prev; 2001 struct rb_node ** rb_link, * rb_parent; 2002 2003 /* 2004 * The vm_pgoff of a purely anonymous vma should be irrelevant 2005 * until its first write fault, when page's anon_vma and index 2006 * are set. But now set the vm_pgoff it will almost certainly 2007 * end up with (unless mremap moves it elsewhere before that 2008 * first wfault), so /proc/pid/maps tells a consistent story. 2009 * 2010 * By setting it to reflect the virtual start address of the 2011 * vma, merges and splits can happen in a seamless way, just 2012 * using the existing file pgoff checks and manipulations. 2013 * Similarly in do_mmap_pgoff and in do_brk. 2014 */ 2015 if (!vma->vm_file) { 2016 BUG_ON(vma->anon_vma); 2017 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2018 } 2019 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2020 if (__vma && __vma->vm_start < vma->vm_end) 2021 return -ENOMEM; 2022 if ((vma->vm_flags & VM_ACCOUNT) && 2023 security_vm_enough_memory(vma_pages(vma))) 2024 return -ENOMEM; 2025 vma_link(mm, vma, prev, rb_link, rb_parent); 2026 return 0; 2027 } 2028 2029 /* 2030 * Copy the vma structure to a new location in the same mm, 2031 * prior to moving page table entries, to effect an mremap move. 2032 */ 2033 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2034 unsigned long addr, unsigned long len, pgoff_t pgoff) 2035 { 2036 struct vm_area_struct *vma = *vmap; 2037 unsigned long vma_start = vma->vm_start; 2038 struct mm_struct *mm = vma->vm_mm; 2039 struct vm_area_struct *new_vma, *prev; 2040 struct rb_node **rb_link, *rb_parent; 2041 struct mempolicy *pol; 2042 2043 /* 2044 * If anonymous vma has not yet been faulted, update new pgoff 2045 * to match new location, to increase its chance of merging. 2046 */ 2047 if (!vma->vm_file && !vma->anon_vma) 2048 pgoff = addr >> PAGE_SHIFT; 2049 2050 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2051 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2052 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2053 if (new_vma) { 2054 /* 2055 * Source vma may have been merged into new_vma 2056 */ 2057 if (vma_start >= new_vma->vm_start && 2058 vma_start < new_vma->vm_end) 2059 *vmap = new_vma; 2060 } else { 2061 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2062 if (new_vma) { 2063 *new_vma = *vma; 2064 pol = mpol_copy(vma_policy(vma)); 2065 if (IS_ERR(pol)) { 2066 kmem_cache_free(vm_area_cachep, new_vma); 2067 return NULL; 2068 } 2069 vma_set_policy(new_vma, pol); 2070 new_vma->vm_start = addr; 2071 new_vma->vm_end = addr + len; 2072 new_vma->vm_pgoff = pgoff; 2073 if (new_vma->vm_file) 2074 get_file(new_vma->vm_file); 2075 if (new_vma->vm_ops && new_vma->vm_ops->open) 2076 new_vma->vm_ops->open(new_vma); 2077 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2078 } 2079 } 2080 return new_vma; 2081 } 2082 2083 /* 2084 * Return true if the calling process may expand its vm space by the passed 2085 * number of pages 2086 */ 2087 int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2088 { 2089 unsigned long cur = mm->total_vm; /* pages */ 2090 unsigned long lim; 2091 2092 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2093 2094 if (cur + npages > lim) 2095 return 0; 2096 return 1; 2097 } 2098 2099 2100 static struct page *special_mapping_nopage(struct vm_area_struct *vma, 2101 unsigned long address, int *type) 2102 { 2103 struct page **pages; 2104 2105 BUG_ON(address < vma->vm_start || address >= vma->vm_end); 2106 2107 address -= vma->vm_start; 2108 for (pages = vma->vm_private_data; address > 0 && *pages; ++pages) 2109 address -= PAGE_SIZE; 2110 2111 if (*pages) { 2112 struct page *page = *pages; 2113 get_page(page); 2114 return page; 2115 } 2116 2117 return NOPAGE_SIGBUS; 2118 } 2119 2120 /* 2121 * Having a close hook prevents vma merging regardless of flags. 2122 */ 2123 static void special_mapping_close(struct vm_area_struct *vma) 2124 { 2125 } 2126 2127 static struct vm_operations_struct special_mapping_vmops = { 2128 .close = special_mapping_close, 2129 .nopage = special_mapping_nopage, 2130 }; 2131 2132 /* 2133 * Called with mm->mmap_sem held for writing. 2134 * Insert a new vma covering the given region, with the given flags. 2135 * Its pages are supplied by the given array of struct page *. 2136 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2137 * The region past the last page supplied will always produce SIGBUS. 2138 * The array pointer and the pages it points to are assumed to stay alive 2139 * for as long as this mapping might exist. 2140 */ 2141 int install_special_mapping(struct mm_struct *mm, 2142 unsigned long addr, unsigned long len, 2143 unsigned long vm_flags, struct page **pages) 2144 { 2145 struct vm_area_struct *vma; 2146 2147 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2148 if (unlikely(vma == NULL)) 2149 return -ENOMEM; 2150 2151 vma->vm_mm = mm; 2152 vma->vm_start = addr; 2153 vma->vm_end = addr + len; 2154 2155 vma->vm_flags = vm_flags | mm->def_flags; 2156 vma->vm_page_prot = protection_map[vma->vm_flags & 7]; 2157 2158 vma->vm_ops = &special_mapping_vmops; 2159 vma->vm_private_data = pages; 2160 2161 if (unlikely(insert_vm_struct(mm, vma))) { 2162 kmem_cache_free(vm_area_cachep, vma); 2163 return -ENOMEM; 2164 } 2165 2166 mm->total_vm += len >> PAGE_SHIFT; 2167 2168 return 0; 2169 } 2170