1 /* 2 * mm/mmap.c 3 * 4 * Written by obz. 5 * 6 * Address space accounting code <alan@lxorguk.ukuu.org.uk> 7 */ 8 9 #include <linux/slab.h> 10 #include <linux/backing-dev.h> 11 #include <linux/mm.h> 12 #include <linux/shm.h> 13 #include <linux/mman.h> 14 #include <linux/pagemap.h> 15 #include <linux/swap.h> 16 #include <linux/syscalls.h> 17 #include <linux/capability.h> 18 #include <linux/init.h> 19 #include <linux/file.h> 20 #include <linux/fs.h> 21 #include <linux/personality.h> 22 #include <linux/security.h> 23 #include <linux/hugetlb.h> 24 #include <linux/profile.h> 25 #include <linux/module.h> 26 #include <linux/mount.h> 27 #include <linux/mempolicy.h> 28 #include <linux/rmap.h> 29 #include <linux/mmu_notifier.h> 30 #include <linux/perf_event.h> 31 32 #include <asm/uaccess.h> 33 #include <asm/cacheflush.h> 34 #include <asm/tlb.h> 35 #include <asm/mmu_context.h> 36 37 #include "internal.h" 38 39 #ifndef arch_mmap_check 40 #define arch_mmap_check(addr, len, flags) (0) 41 #endif 42 43 #ifndef arch_rebalance_pgtables 44 #define arch_rebalance_pgtables(addr, len) (addr) 45 #endif 46 47 static void unmap_region(struct mm_struct *mm, 48 struct vm_area_struct *vma, struct vm_area_struct *prev, 49 unsigned long start, unsigned long end); 50 51 /* 52 * WARNING: the debugging will use recursive algorithms so never enable this 53 * unless you know what you are doing. 54 */ 55 #undef DEBUG_MM_RB 56 57 /* description of effects of mapping type and prot in current implementation. 58 * this is due to the limited x86 page protection hardware. The expected 59 * behavior is in parens: 60 * 61 * map_type prot 62 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 63 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 64 * w: (no) no w: (no) no w: (yes) yes w: (no) no 65 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 66 * 67 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 68 * w: (no) no w: (no) no w: (copy) copy w: (no) no 69 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 70 * 71 */ 72 pgprot_t protection_map[16] = { 73 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 74 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 75 }; 76 77 pgprot_t vm_get_page_prot(unsigned long vm_flags) 78 { 79 return __pgprot(pgprot_val(protection_map[vm_flags & 80 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | 81 pgprot_val(arch_vm_get_page_prot(vm_flags))); 82 } 83 EXPORT_SYMBOL(vm_get_page_prot); 84 85 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 86 int sysctl_overcommit_ratio = 50; /* default is 50% */ 87 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 88 struct percpu_counter vm_committed_as; 89 90 /* 91 * Check that a process has enough memory to allocate a new virtual 92 * mapping. 0 means there is enough memory for the allocation to 93 * succeed and -ENOMEM implies there is not. 94 * 95 * We currently support three overcommit policies, which are set via the 96 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 97 * 98 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 99 * Additional code 2002 Jul 20 by Robert Love. 100 * 101 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 102 * 103 * Note this is a helper function intended to be used by LSMs which 104 * wish to use this logic. 105 */ 106 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 107 { 108 unsigned long free, allowed; 109 110 vm_acct_memory(pages); 111 112 /* 113 * Sometimes we want to use more memory than we have 114 */ 115 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 116 return 0; 117 118 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 119 unsigned long n; 120 121 free = global_page_state(NR_FILE_PAGES); 122 free += nr_swap_pages; 123 124 /* 125 * Any slabs which are created with the 126 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 127 * which are reclaimable, under pressure. The dentry 128 * cache and most inode caches should fall into this 129 */ 130 free += global_page_state(NR_SLAB_RECLAIMABLE); 131 132 /* 133 * Leave the last 3% for root 134 */ 135 if (!cap_sys_admin) 136 free -= free / 32; 137 138 if (free > pages) 139 return 0; 140 141 /* 142 * nr_free_pages() is very expensive on large systems, 143 * only call if we're about to fail. 144 */ 145 n = nr_free_pages(); 146 147 /* 148 * Leave reserved pages. The pages are not for anonymous pages. 149 */ 150 if (n <= totalreserve_pages) 151 goto error; 152 else 153 n -= totalreserve_pages; 154 155 /* 156 * Leave the last 3% for root 157 */ 158 if (!cap_sys_admin) 159 n -= n / 32; 160 free += n; 161 162 if (free > pages) 163 return 0; 164 165 goto error; 166 } 167 168 allowed = (totalram_pages - hugetlb_total_pages()) 169 * sysctl_overcommit_ratio / 100; 170 /* 171 * Leave the last 3% for root 172 */ 173 if (!cap_sys_admin) 174 allowed -= allowed / 32; 175 allowed += total_swap_pages; 176 177 /* Don't let a single process grow too big: 178 leave 3% of the size of this process for other processes */ 179 if (mm) 180 allowed -= mm->total_vm / 32; 181 182 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 183 return 0; 184 error: 185 vm_unacct_memory(pages); 186 187 return -ENOMEM; 188 } 189 190 /* 191 * Requires inode->i_mapping->i_mmap_lock 192 */ 193 static void __remove_shared_vm_struct(struct vm_area_struct *vma, 194 struct file *file, struct address_space *mapping) 195 { 196 if (vma->vm_flags & VM_DENYWRITE) 197 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 198 if (vma->vm_flags & VM_SHARED) 199 mapping->i_mmap_writable--; 200 201 flush_dcache_mmap_lock(mapping); 202 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 203 list_del_init(&vma->shared.vm_set.list); 204 else 205 vma_prio_tree_remove(vma, &mapping->i_mmap); 206 flush_dcache_mmap_unlock(mapping); 207 } 208 209 /* 210 * Unlink a file-based vm structure from its prio_tree, to hide 211 * vma from rmap and vmtruncate before freeing its page tables. 212 */ 213 void unlink_file_vma(struct vm_area_struct *vma) 214 { 215 struct file *file = vma->vm_file; 216 217 if (file) { 218 struct address_space *mapping = file->f_mapping; 219 spin_lock(&mapping->i_mmap_lock); 220 __remove_shared_vm_struct(vma, file, mapping); 221 spin_unlock(&mapping->i_mmap_lock); 222 } 223 } 224 225 /* 226 * Close a vm structure and free it, returning the next. 227 */ 228 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 229 { 230 struct vm_area_struct *next = vma->vm_next; 231 232 might_sleep(); 233 if (vma->vm_ops && vma->vm_ops->close) 234 vma->vm_ops->close(vma); 235 if (vma->vm_file) { 236 fput(vma->vm_file); 237 if (vma->vm_flags & VM_EXECUTABLE) 238 removed_exe_file_vma(vma->vm_mm); 239 } 240 mpol_put(vma_policy(vma)); 241 kmem_cache_free(vm_area_cachep, vma); 242 return next; 243 } 244 245 SYSCALL_DEFINE1(brk, unsigned long, brk) 246 { 247 unsigned long rlim, retval; 248 unsigned long newbrk, oldbrk; 249 struct mm_struct *mm = current->mm; 250 unsigned long min_brk; 251 252 down_write(&mm->mmap_sem); 253 254 #ifdef CONFIG_COMPAT_BRK 255 min_brk = mm->end_code; 256 #else 257 min_brk = mm->start_brk; 258 #endif 259 if (brk < min_brk) 260 goto out; 261 262 /* 263 * Check against rlimit here. If this check is done later after the test 264 * of oldbrk with newbrk then it can escape the test and let the data 265 * segment grow beyond its set limit the in case where the limit is 266 * not page aligned -Ram Gupta 267 */ 268 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 269 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + 270 (mm->end_data - mm->start_data) > rlim) 271 goto out; 272 273 newbrk = PAGE_ALIGN(brk); 274 oldbrk = PAGE_ALIGN(mm->brk); 275 if (oldbrk == newbrk) 276 goto set_brk; 277 278 /* Always allow shrinking brk. */ 279 if (brk <= mm->brk) { 280 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 281 goto set_brk; 282 goto out; 283 } 284 285 /* Check against existing mmap mappings. */ 286 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 287 goto out; 288 289 /* Ok, looks good - let it rip. */ 290 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 291 goto out; 292 set_brk: 293 mm->brk = brk; 294 out: 295 retval = mm->brk; 296 up_write(&mm->mmap_sem); 297 return retval; 298 } 299 300 #ifdef DEBUG_MM_RB 301 static int browse_rb(struct rb_root *root) 302 { 303 int i = 0, j; 304 struct rb_node *nd, *pn = NULL; 305 unsigned long prev = 0, pend = 0; 306 307 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 308 struct vm_area_struct *vma; 309 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 310 if (vma->vm_start < prev) 311 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 312 if (vma->vm_start < pend) 313 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 314 if (vma->vm_start > vma->vm_end) 315 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 316 i++; 317 pn = nd; 318 prev = vma->vm_start; 319 pend = vma->vm_end; 320 } 321 j = 0; 322 for (nd = pn; nd; nd = rb_prev(nd)) { 323 j++; 324 } 325 if (i != j) 326 printk("backwards %d, forwards %d\n", j, i), i = 0; 327 return i; 328 } 329 330 void validate_mm(struct mm_struct *mm) 331 { 332 int bug = 0; 333 int i = 0; 334 struct vm_area_struct *tmp = mm->mmap; 335 while (tmp) { 336 tmp = tmp->vm_next; 337 i++; 338 } 339 if (i != mm->map_count) 340 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 341 i = browse_rb(&mm->mm_rb); 342 if (i != mm->map_count) 343 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 344 BUG_ON(bug); 345 } 346 #else 347 #define validate_mm(mm) do { } while (0) 348 #endif 349 350 static struct vm_area_struct * 351 find_vma_prepare(struct mm_struct *mm, unsigned long addr, 352 struct vm_area_struct **pprev, struct rb_node ***rb_link, 353 struct rb_node ** rb_parent) 354 { 355 struct vm_area_struct * vma; 356 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 357 358 __rb_link = &mm->mm_rb.rb_node; 359 rb_prev = __rb_parent = NULL; 360 vma = NULL; 361 362 while (*__rb_link) { 363 struct vm_area_struct *vma_tmp; 364 365 __rb_parent = *__rb_link; 366 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 367 368 if (vma_tmp->vm_end > addr) { 369 vma = vma_tmp; 370 if (vma_tmp->vm_start <= addr) 371 break; 372 __rb_link = &__rb_parent->rb_left; 373 } else { 374 rb_prev = __rb_parent; 375 __rb_link = &__rb_parent->rb_right; 376 } 377 } 378 379 *pprev = NULL; 380 if (rb_prev) 381 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 382 *rb_link = __rb_link; 383 *rb_parent = __rb_parent; 384 return vma; 385 } 386 387 static inline void 388 __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 389 struct vm_area_struct *prev, struct rb_node *rb_parent) 390 { 391 if (prev) { 392 vma->vm_next = prev->vm_next; 393 prev->vm_next = vma; 394 } else { 395 mm->mmap = vma; 396 if (rb_parent) 397 vma->vm_next = rb_entry(rb_parent, 398 struct vm_area_struct, vm_rb); 399 else 400 vma->vm_next = NULL; 401 } 402 } 403 404 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 405 struct rb_node **rb_link, struct rb_node *rb_parent) 406 { 407 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 408 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 409 } 410 411 static void __vma_link_file(struct vm_area_struct *vma) 412 { 413 struct file *file; 414 415 file = vma->vm_file; 416 if (file) { 417 struct address_space *mapping = file->f_mapping; 418 419 if (vma->vm_flags & VM_DENYWRITE) 420 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 421 if (vma->vm_flags & VM_SHARED) 422 mapping->i_mmap_writable++; 423 424 flush_dcache_mmap_lock(mapping); 425 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 426 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 427 else 428 vma_prio_tree_insert(vma, &mapping->i_mmap); 429 flush_dcache_mmap_unlock(mapping); 430 } 431 } 432 433 static void 434 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 435 struct vm_area_struct *prev, struct rb_node **rb_link, 436 struct rb_node *rb_parent) 437 { 438 __vma_link_list(mm, vma, prev, rb_parent); 439 __vma_link_rb(mm, vma, rb_link, rb_parent); 440 __anon_vma_link(vma); 441 } 442 443 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 444 struct vm_area_struct *prev, struct rb_node **rb_link, 445 struct rb_node *rb_parent) 446 { 447 struct address_space *mapping = NULL; 448 449 if (vma->vm_file) 450 mapping = vma->vm_file->f_mapping; 451 452 if (mapping) { 453 spin_lock(&mapping->i_mmap_lock); 454 vma->vm_truncate_count = mapping->truncate_count; 455 } 456 anon_vma_lock(vma); 457 458 __vma_link(mm, vma, prev, rb_link, rb_parent); 459 __vma_link_file(vma); 460 461 anon_vma_unlock(vma); 462 if (mapping) 463 spin_unlock(&mapping->i_mmap_lock); 464 465 mm->map_count++; 466 validate_mm(mm); 467 } 468 469 /* 470 * Helper for vma_adjust in the split_vma insert case: 471 * insert vm structure into list and rbtree and anon_vma, 472 * but it has already been inserted into prio_tree earlier. 473 */ 474 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 475 { 476 struct vm_area_struct *__vma, *prev; 477 struct rb_node **rb_link, *rb_parent; 478 479 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 480 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 481 __vma_link(mm, vma, prev, rb_link, rb_parent); 482 mm->map_count++; 483 } 484 485 static inline void 486 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 487 struct vm_area_struct *prev) 488 { 489 prev->vm_next = vma->vm_next; 490 rb_erase(&vma->vm_rb, &mm->mm_rb); 491 if (mm->mmap_cache == vma) 492 mm->mmap_cache = prev; 493 } 494 495 /* 496 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 497 * is already present in an i_mmap tree without adjusting the tree. 498 * The following helper function should be used when such adjustments 499 * are necessary. The "insert" vma (if any) is to be inserted 500 * before we drop the necessary locks. 501 */ 502 void vma_adjust(struct vm_area_struct *vma, unsigned long start, 503 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 504 { 505 struct mm_struct *mm = vma->vm_mm; 506 struct vm_area_struct *next = vma->vm_next; 507 struct vm_area_struct *importer = NULL; 508 struct address_space *mapping = NULL; 509 struct prio_tree_root *root = NULL; 510 struct file *file = vma->vm_file; 511 struct anon_vma *anon_vma = NULL; 512 long adjust_next = 0; 513 int remove_next = 0; 514 515 if (next && !insert) { 516 if (end >= next->vm_end) { 517 /* 518 * vma expands, overlapping all the next, and 519 * perhaps the one after too (mprotect case 6). 520 */ 521 again: remove_next = 1 + (end > next->vm_end); 522 end = next->vm_end; 523 anon_vma = next->anon_vma; 524 importer = vma; 525 } else if (end > next->vm_start) { 526 /* 527 * vma expands, overlapping part of the next: 528 * mprotect case 5 shifting the boundary up. 529 */ 530 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 531 anon_vma = next->anon_vma; 532 importer = vma; 533 } else if (end < vma->vm_end) { 534 /* 535 * vma shrinks, and !insert tells it's not 536 * split_vma inserting another: so it must be 537 * mprotect case 4 shifting the boundary down. 538 */ 539 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 540 anon_vma = next->anon_vma; 541 importer = next; 542 } 543 } 544 545 if (file) { 546 mapping = file->f_mapping; 547 if (!(vma->vm_flags & VM_NONLINEAR)) 548 root = &mapping->i_mmap; 549 spin_lock(&mapping->i_mmap_lock); 550 if (importer && 551 vma->vm_truncate_count != next->vm_truncate_count) { 552 /* 553 * unmap_mapping_range might be in progress: 554 * ensure that the expanding vma is rescanned. 555 */ 556 importer->vm_truncate_count = 0; 557 } 558 if (insert) { 559 insert->vm_truncate_count = vma->vm_truncate_count; 560 /* 561 * Put into prio_tree now, so instantiated pages 562 * are visible to arm/parisc __flush_dcache_page 563 * throughout; but we cannot insert into address 564 * space until vma start or end is updated. 565 */ 566 __vma_link_file(insert); 567 } 568 } 569 570 /* 571 * When changing only vma->vm_end, we don't really need 572 * anon_vma lock. 573 */ 574 if (vma->anon_vma && (insert || importer || start != vma->vm_start)) 575 anon_vma = vma->anon_vma; 576 if (anon_vma) { 577 spin_lock(&anon_vma->lock); 578 /* 579 * Easily overlooked: when mprotect shifts the boundary, 580 * make sure the expanding vma has anon_vma set if the 581 * shrinking vma had, to cover any anon pages imported. 582 */ 583 if (importer && !importer->anon_vma) { 584 importer->anon_vma = anon_vma; 585 __anon_vma_link(importer); 586 } 587 } 588 589 if (root) { 590 flush_dcache_mmap_lock(mapping); 591 vma_prio_tree_remove(vma, root); 592 if (adjust_next) 593 vma_prio_tree_remove(next, root); 594 } 595 596 vma->vm_start = start; 597 vma->vm_end = end; 598 vma->vm_pgoff = pgoff; 599 if (adjust_next) { 600 next->vm_start += adjust_next << PAGE_SHIFT; 601 next->vm_pgoff += adjust_next; 602 } 603 604 if (root) { 605 if (adjust_next) 606 vma_prio_tree_insert(next, root); 607 vma_prio_tree_insert(vma, root); 608 flush_dcache_mmap_unlock(mapping); 609 } 610 611 if (remove_next) { 612 /* 613 * vma_merge has merged next into vma, and needs 614 * us to remove next before dropping the locks. 615 */ 616 __vma_unlink(mm, next, vma); 617 if (file) 618 __remove_shared_vm_struct(next, file, mapping); 619 if (next->anon_vma) 620 __anon_vma_merge(vma, next); 621 } else if (insert) { 622 /* 623 * split_vma has split insert from vma, and needs 624 * us to insert it before dropping the locks 625 * (it may either follow vma or precede it). 626 */ 627 __insert_vm_struct(mm, insert); 628 } 629 630 if (anon_vma) 631 spin_unlock(&anon_vma->lock); 632 if (mapping) 633 spin_unlock(&mapping->i_mmap_lock); 634 635 if (remove_next) { 636 if (file) { 637 fput(file); 638 if (next->vm_flags & VM_EXECUTABLE) 639 removed_exe_file_vma(mm); 640 } 641 mm->map_count--; 642 mpol_put(vma_policy(next)); 643 kmem_cache_free(vm_area_cachep, next); 644 /* 645 * In mprotect's case 6 (see comments on vma_merge), 646 * we must remove another next too. It would clutter 647 * up the code too much to do both in one go. 648 */ 649 if (remove_next == 2) { 650 next = vma->vm_next; 651 goto again; 652 } 653 } 654 655 validate_mm(mm); 656 } 657 658 /* 659 * If the vma has a ->close operation then the driver probably needs to release 660 * per-vma resources, so we don't attempt to merge those. 661 */ 662 static inline int is_mergeable_vma(struct vm_area_struct *vma, 663 struct file *file, unsigned long vm_flags) 664 { 665 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */ 666 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR) 667 return 0; 668 if (vma->vm_file != file) 669 return 0; 670 if (vma->vm_ops && vma->vm_ops->close) 671 return 0; 672 return 1; 673 } 674 675 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 676 struct anon_vma *anon_vma2) 677 { 678 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 679 } 680 681 /* 682 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 683 * in front of (at a lower virtual address and file offset than) the vma. 684 * 685 * We cannot merge two vmas if they have differently assigned (non-NULL) 686 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 687 * 688 * We don't check here for the merged mmap wrapping around the end of pagecache 689 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 690 * wrap, nor mmaps which cover the final page at index -1UL. 691 */ 692 static int 693 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 694 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 695 { 696 if (is_mergeable_vma(vma, file, vm_flags) && 697 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 698 if (vma->vm_pgoff == vm_pgoff) 699 return 1; 700 } 701 return 0; 702 } 703 704 /* 705 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 706 * beyond (at a higher virtual address and file offset than) the vma. 707 * 708 * We cannot merge two vmas if they have differently assigned (non-NULL) 709 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 710 */ 711 static int 712 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 713 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 714 { 715 if (is_mergeable_vma(vma, file, vm_flags) && 716 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 717 pgoff_t vm_pglen; 718 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 719 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 720 return 1; 721 } 722 return 0; 723 } 724 725 /* 726 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 727 * whether that can be merged with its predecessor or its successor. 728 * Or both (it neatly fills a hole). 729 * 730 * In most cases - when called for mmap, brk or mremap - [addr,end) is 731 * certain not to be mapped by the time vma_merge is called; but when 732 * called for mprotect, it is certain to be already mapped (either at 733 * an offset within prev, or at the start of next), and the flags of 734 * this area are about to be changed to vm_flags - and the no-change 735 * case has already been eliminated. 736 * 737 * The following mprotect cases have to be considered, where AAAA is 738 * the area passed down from mprotect_fixup, never extending beyond one 739 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 740 * 741 * AAAA AAAA AAAA AAAA 742 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 743 * cannot merge might become might become might become 744 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 745 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 746 * mremap move: PPPPNNNNNNNN 8 747 * AAAA 748 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 749 * might become case 1 below case 2 below case 3 below 750 * 751 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 752 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 753 */ 754 struct vm_area_struct *vma_merge(struct mm_struct *mm, 755 struct vm_area_struct *prev, unsigned long addr, 756 unsigned long end, unsigned long vm_flags, 757 struct anon_vma *anon_vma, struct file *file, 758 pgoff_t pgoff, struct mempolicy *policy) 759 { 760 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 761 struct vm_area_struct *area, *next; 762 763 /* 764 * We later require that vma->vm_flags == vm_flags, 765 * so this tests vma->vm_flags & VM_SPECIAL, too. 766 */ 767 if (vm_flags & VM_SPECIAL) 768 return NULL; 769 770 if (prev) 771 next = prev->vm_next; 772 else 773 next = mm->mmap; 774 area = next; 775 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 776 next = next->vm_next; 777 778 /* 779 * Can it merge with the predecessor? 780 */ 781 if (prev && prev->vm_end == addr && 782 mpol_equal(vma_policy(prev), policy) && 783 can_vma_merge_after(prev, vm_flags, 784 anon_vma, file, pgoff)) { 785 /* 786 * OK, it can. Can we now merge in the successor as well? 787 */ 788 if (next && end == next->vm_start && 789 mpol_equal(policy, vma_policy(next)) && 790 can_vma_merge_before(next, vm_flags, 791 anon_vma, file, pgoff+pglen) && 792 is_mergeable_anon_vma(prev->anon_vma, 793 next->anon_vma)) { 794 /* cases 1, 6 */ 795 vma_adjust(prev, prev->vm_start, 796 next->vm_end, prev->vm_pgoff, NULL); 797 } else /* cases 2, 5, 7 */ 798 vma_adjust(prev, prev->vm_start, 799 end, prev->vm_pgoff, NULL); 800 return prev; 801 } 802 803 /* 804 * Can this new request be merged in front of next? 805 */ 806 if (next && end == next->vm_start && 807 mpol_equal(policy, vma_policy(next)) && 808 can_vma_merge_before(next, vm_flags, 809 anon_vma, file, pgoff+pglen)) { 810 if (prev && addr < prev->vm_end) /* case 4 */ 811 vma_adjust(prev, prev->vm_start, 812 addr, prev->vm_pgoff, NULL); 813 else /* cases 3, 8 */ 814 vma_adjust(area, addr, next->vm_end, 815 next->vm_pgoff - pglen, NULL); 816 return area; 817 } 818 819 return NULL; 820 } 821 822 /* 823 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 824 * neighbouring vmas for a suitable anon_vma, before it goes off 825 * to allocate a new anon_vma. It checks because a repetitive 826 * sequence of mprotects and faults may otherwise lead to distinct 827 * anon_vmas being allocated, preventing vma merge in subsequent 828 * mprotect. 829 */ 830 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 831 { 832 struct vm_area_struct *near; 833 unsigned long vm_flags; 834 835 near = vma->vm_next; 836 if (!near) 837 goto try_prev; 838 839 /* 840 * Since only mprotect tries to remerge vmas, match flags 841 * which might be mprotected into each other later on. 842 * Neither mlock nor madvise tries to remerge at present, 843 * so leave their flags as obstructing a merge. 844 */ 845 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 846 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 847 848 if (near->anon_vma && vma->vm_end == near->vm_start && 849 mpol_equal(vma_policy(vma), vma_policy(near)) && 850 can_vma_merge_before(near, vm_flags, 851 NULL, vma->vm_file, vma->vm_pgoff + 852 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 853 return near->anon_vma; 854 try_prev: 855 /* 856 * It is potentially slow to have to call find_vma_prev here. 857 * But it's only on the first write fault on the vma, not 858 * every time, and we could devise a way to avoid it later 859 * (e.g. stash info in next's anon_vma_node when assigning 860 * an anon_vma, or when trying vma_merge). Another time. 861 */ 862 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 863 if (!near) 864 goto none; 865 866 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 867 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 868 869 if (near->anon_vma && near->vm_end == vma->vm_start && 870 mpol_equal(vma_policy(near), vma_policy(vma)) && 871 can_vma_merge_after(near, vm_flags, 872 NULL, vma->vm_file, vma->vm_pgoff)) 873 return near->anon_vma; 874 none: 875 /* 876 * There's no absolute need to look only at touching neighbours: 877 * we could search further afield for "compatible" anon_vmas. 878 * But it would probably just be a waste of time searching, 879 * or lead to too many vmas hanging off the same anon_vma. 880 * We're trying to allow mprotect remerging later on, 881 * not trying to minimize memory used for anon_vmas. 882 */ 883 return NULL; 884 } 885 886 #ifdef CONFIG_PROC_FS 887 void vm_stat_account(struct mm_struct *mm, unsigned long flags, 888 struct file *file, long pages) 889 { 890 const unsigned long stack_flags 891 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 892 893 if (file) { 894 mm->shared_vm += pages; 895 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 896 mm->exec_vm += pages; 897 } else if (flags & stack_flags) 898 mm->stack_vm += pages; 899 if (flags & (VM_RESERVED|VM_IO)) 900 mm->reserved_vm += pages; 901 } 902 #endif /* CONFIG_PROC_FS */ 903 904 /* 905 * The caller must hold down_write(¤t->mm->mmap_sem). 906 */ 907 908 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, 909 unsigned long len, unsigned long prot, 910 unsigned long flags, unsigned long pgoff) 911 { 912 struct mm_struct * mm = current->mm; 913 struct inode *inode; 914 unsigned int vm_flags; 915 int error; 916 unsigned long reqprot = prot; 917 918 /* 919 * Does the application expect PROT_READ to imply PROT_EXEC? 920 * 921 * (the exception is when the underlying filesystem is noexec 922 * mounted, in which case we dont add PROT_EXEC.) 923 */ 924 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 925 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 926 prot |= PROT_EXEC; 927 928 if (!len) 929 return -EINVAL; 930 931 if (!(flags & MAP_FIXED)) 932 addr = round_hint_to_min(addr); 933 934 error = arch_mmap_check(addr, len, flags); 935 if (error) 936 return error; 937 938 /* Careful about overflows.. */ 939 len = PAGE_ALIGN(len); 940 if (!len || len > TASK_SIZE) 941 return -ENOMEM; 942 943 /* offset overflow? */ 944 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 945 return -EOVERFLOW; 946 947 /* Too many mappings? */ 948 if (mm->map_count > sysctl_max_map_count) 949 return -ENOMEM; 950 951 if (flags & MAP_HUGETLB) { 952 struct user_struct *user = NULL; 953 if (file) 954 return -EINVAL; 955 956 /* 957 * VM_NORESERVE is used because the reservations will be 958 * taken when vm_ops->mmap() is called 959 * A dummy user value is used because we are not locking 960 * memory so no accounting is necessary 961 */ 962 len = ALIGN(len, huge_page_size(&default_hstate)); 963 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, VM_NORESERVE, 964 &user, HUGETLB_ANONHUGE_INODE); 965 if (IS_ERR(file)) 966 return PTR_ERR(file); 967 } 968 969 /* Obtain the address to map to. we verify (or select) it and ensure 970 * that it represents a valid section of the address space. 971 */ 972 addr = get_unmapped_area(file, addr, len, pgoff, flags); 973 if (addr & ~PAGE_MASK) 974 return addr; 975 976 /* Do simple checking here so the lower-level routines won't have 977 * to. we assume access permissions have been handled by the open 978 * of the memory object, so we don't do any here. 979 */ 980 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 981 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 982 983 if (flags & MAP_LOCKED) 984 if (!can_do_mlock()) 985 return -EPERM; 986 987 /* mlock MCL_FUTURE? */ 988 if (vm_flags & VM_LOCKED) { 989 unsigned long locked, lock_limit; 990 locked = len >> PAGE_SHIFT; 991 locked += mm->locked_vm; 992 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 993 lock_limit >>= PAGE_SHIFT; 994 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 995 return -EAGAIN; 996 } 997 998 inode = file ? file->f_path.dentry->d_inode : NULL; 999 1000 if (file) { 1001 switch (flags & MAP_TYPE) { 1002 case MAP_SHARED: 1003 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 1004 return -EACCES; 1005 1006 /* 1007 * Make sure we don't allow writing to an append-only 1008 * file.. 1009 */ 1010 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 1011 return -EACCES; 1012 1013 /* 1014 * Make sure there are no mandatory locks on the file. 1015 */ 1016 if (locks_verify_locked(inode)) 1017 return -EAGAIN; 1018 1019 vm_flags |= VM_SHARED | VM_MAYSHARE; 1020 if (!(file->f_mode & FMODE_WRITE)) 1021 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1022 1023 /* fall through */ 1024 case MAP_PRIVATE: 1025 if (!(file->f_mode & FMODE_READ)) 1026 return -EACCES; 1027 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1028 if (vm_flags & VM_EXEC) 1029 return -EPERM; 1030 vm_flags &= ~VM_MAYEXEC; 1031 } 1032 1033 if (!file->f_op || !file->f_op->mmap) 1034 return -ENODEV; 1035 break; 1036 1037 default: 1038 return -EINVAL; 1039 } 1040 } else { 1041 switch (flags & MAP_TYPE) { 1042 case MAP_SHARED: 1043 /* 1044 * Ignore pgoff. 1045 */ 1046 pgoff = 0; 1047 vm_flags |= VM_SHARED | VM_MAYSHARE; 1048 break; 1049 case MAP_PRIVATE: 1050 /* 1051 * Set pgoff according to addr for anon_vma. 1052 */ 1053 pgoff = addr >> PAGE_SHIFT; 1054 break; 1055 default: 1056 return -EINVAL; 1057 } 1058 } 1059 1060 error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1061 if (error) 1062 return error; 1063 1064 return mmap_region(file, addr, len, flags, vm_flags, pgoff); 1065 } 1066 EXPORT_SYMBOL(do_mmap_pgoff); 1067 1068 /* 1069 * Some shared mappigns will want the pages marked read-only 1070 * to track write events. If so, we'll downgrade vm_page_prot 1071 * to the private version (using protection_map[] without the 1072 * VM_SHARED bit). 1073 */ 1074 int vma_wants_writenotify(struct vm_area_struct *vma) 1075 { 1076 unsigned int vm_flags = vma->vm_flags; 1077 1078 /* If it was private or non-writable, the write bit is already clear */ 1079 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1080 return 0; 1081 1082 /* The backer wishes to know when pages are first written to? */ 1083 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1084 return 1; 1085 1086 /* The open routine did something to the protections already? */ 1087 if (pgprot_val(vma->vm_page_prot) != 1088 pgprot_val(vm_get_page_prot(vm_flags))) 1089 return 0; 1090 1091 /* Specialty mapping? */ 1092 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) 1093 return 0; 1094 1095 /* Can the mapping track the dirty pages? */ 1096 return vma->vm_file && vma->vm_file->f_mapping && 1097 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1098 } 1099 1100 /* 1101 * We account for memory if it's a private writeable mapping, 1102 * not hugepages and VM_NORESERVE wasn't set. 1103 */ 1104 static inline int accountable_mapping(struct file *file, unsigned int vm_flags) 1105 { 1106 /* 1107 * hugetlb has its own accounting separate from the core VM 1108 * VM_HUGETLB may not be set yet so we cannot check for that flag. 1109 */ 1110 if (file && is_file_hugepages(file)) 1111 return 0; 1112 1113 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; 1114 } 1115 1116 unsigned long mmap_region(struct file *file, unsigned long addr, 1117 unsigned long len, unsigned long flags, 1118 unsigned int vm_flags, unsigned long pgoff) 1119 { 1120 struct mm_struct *mm = current->mm; 1121 struct vm_area_struct *vma, *prev; 1122 int correct_wcount = 0; 1123 int error; 1124 struct rb_node **rb_link, *rb_parent; 1125 unsigned long charged = 0; 1126 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; 1127 1128 /* Clear old maps */ 1129 error = -ENOMEM; 1130 munmap_back: 1131 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1132 if (vma && vma->vm_start < addr + len) { 1133 if (do_munmap(mm, addr, len)) 1134 return -ENOMEM; 1135 goto munmap_back; 1136 } 1137 1138 /* Check against address space limit. */ 1139 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1140 return -ENOMEM; 1141 1142 /* 1143 * Set 'VM_NORESERVE' if we should not account for the 1144 * memory use of this mapping. 1145 */ 1146 if ((flags & MAP_NORESERVE)) { 1147 /* We honor MAP_NORESERVE if allowed to overcommit */ 1148 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) 1149 vm_flags |= VM_NORESERVE; 1150 1151 /* hugetlb applies strict overcommit unless MAP_NORESERVE */ 1152 if (file && is_file_hugepages(file)) 1153 vm_flags |= VM_NORESERVE; 1154 } 1155 1156 /* 1157 * Private writable mapping: check memory availability 1158 */ 1159 if (accountable_mapping(file, vm_flags)) { 1160 charged = len >> PAGE_SHIFT; 1161 if (security_vm_enough_memory(charged)) 1162 return -ENOMEM; 1163 vm_flags |= VM_ACCOUNT; 1164 } 1165 1166 /* 1167 * Can we just expand an old mapping? 1168 */ 1169 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL); 1170 if (vma) 1171 goto out; 1172 1173 /* 1174 * Determine the object being mapped and call the appropriate 1175 * specific mapper. the address has already been validated, but 1176 * not unmapped, but the maps are removed from the list. 1177 */ 1178 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1179 if (!vma) { 1180 error = -ENOMEM; 1181 goto unacct_error; 1182 } 1183 1184 vma->vm_mm = mm; 1185 vma->vm_start = addr; 1186 vma->vm_end = addr + len; 1187 vma->vm_flags = vm_flags; 1188 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1189 vma->vm_pgoff = pgoff; 1190 1191 if (file) { 1192 error = -EINVAL; 1193 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1194 goto free_vma; 1195 if (vm_flags & VM_DENYWRITE) { 1196 error = deny_write_access(file); 1197 if (error) 1198 goto free_vma; 1199 correct_wcount = 1; 1200 } 1201 vma->vm_file = file; 1202 get_file(file); 1203 error = file->f_op->mmap(file, vma); 1204 if (error) 1205 goto unmap_and_free_vma; 1206 if (vm_flags & VM_EXECUTABLE) 1207 added_exe_file_vma(mm); 1208 1209 /* Can addr have changed?? 1210 * 1211 * Answer: Yes, several device drivers can do it in their 1212 * f_op->mmap method. -DaveM 1213 */ 1214 addr = vma->vm_start; 1215 pgoff = vma->vm_pgoff; 1216 vm_flags = vma->vm_flags; 1217 } else if (vm_flags & VM_SHARED) { 1218 error = shmem_zero_setup(vma); 1219 if (error) 1220 goto free_vma; 1221 } 1222 1223 if (vma_wants_writenotify(vma)) 1224 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); 1225 1226 vma_link(mm, vma, prev, rb_link, rb_parent); 1227 file = vma->vm_file; 1228 1229 /* Once vma denies write, undo our temporary denial count */ 1230 if (correct_wcount) 1231 atomic_inc(&inode->i_writecount); 1232 out: 1233 perf_event_mmap(vma); 1234 1235 mm->total_vm += len >> PAGE_SHIFT; 1236 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1237 if (vm_flags & VM_LOCKED) { 1238 /* 1239 * makes pages present; downgrades, drops, reacquires mmap_sem 1240 */ 1241 long nr_pages = mlock_vma_pages_range(vma, addr, addr + len); 1242 if (nr_pages < 0) 1243 return nr_pages; /* vma gone! */ 1244 mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages; 1245 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) 1246 make_pages_present(addr, addr + len); 1247 return addr; 1248 1249 unmap_and_free_vma: 1250 if (correct_wcount) 1251 atomic_inc(&inode->i_writecount); 1252 vma->vm_file = NULL; 1253 fput(file); 1254 1255 /* Undo any partial mapping done by a device driver. */ 1256 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1257 charged = 0; 1258 free_vma: 1259 kmem_cache_free(vm_area_cachep, vma); 1260 unacct_error: 1261 if (charged) 1262 vm_unacct_memory(charged); 1263 return error; 1264 } 1265 1266 /* Get an address range which is currently unmapped. 1267 * For shmat() with addr=0. 1268 * 1269 * Ugly calling convention alert: 1270 * Return value with the low bits set means error value, 1271 * ie 1272 * if (ret & ~PAGE_MASK) 1273 * error = ret; 1274 * 1275 * This function "knows" that -ENOMEM has the bits set. 1276 */ 1277 #ifndef HAVE_ARCH_UNMAPPED_AREA 1278 unsigned long 1279 arch_get_unmapped_area(struct file *filp, unsigned long addr, 1280 unsigned long len, unsigned long pgoff, unsigned long flags) 1281 { 1282 struct mm_struct *mm = current->mm; 1283 struct vm_area_struct *vma; 1284 unsigned long start_addr; 1285 1286 if (len > TASK_SIZE) 1287 return -ENOMEM; 1288 1289 if (flags & MAP_FIXED) 1290 return addr; 1291 1292 if (addr) { 1293 addr = PAGE_ALIGN(addr); 1294 vma = find_vma(mm, addr); 1295 if (TASK_SIZE - len >= addr && 1296 (!vma || addr + len <= vma->vm_start)) 1297 return addr; 1298 } 1299 if (len > mm->cached_hole_size) { 1300 start_addr = addr = mm->free_area_cache; 1301 } else { 1302 start_addr = addr = TASK_UNMAPPED_BASE; 1303 mm->cached_hole_size = 0; 1304 } 1305 1306 full_search: 1307 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1308 /* At this point: (!vma || addr < vma->vm_end). */ 1309 if (TASK_SIZE - len < addr) { 1310 /* 1311 * Start a new search - just in case we missed 1312 * some holes. 1313 */ 1314 if (start_addr != TASK_UNMAPPED_BASE) { 1315 addr = TASK_UNMAPPED_BASE; 1316 start_addr = addr; 1317 mm->cached_hole_size = 0; 1318 goto full_search; 1319 } 1320 return -ENOMEM; 1321 } 1322 if (!vma || addr + len <= vma->vm_start) { 1323 /* 1324 * Remember the place where we stopped the search: 1325 */ 1326 mm->free_area_cache = addr + len; 1327 return addr; 1328 } 1329 if (addr + mm->cached_hole_size < vma->vm_start) 1330 mm->cached_hole_size = vma->vm_start - addr; 1331 addr = vma->vm_end; 1332 } 1333 } 1334 #endif 1335 1336 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1337 { 1338 /* 1339 * Is this a new hole at the lowest possible address? 1340 */ 1341 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1342 mm->free_area_cache = addr; 1343 mm->cached_hole_size = ~0UL; 1344 } 1345 } 1346 1347 /* 1348 * This mmap-allocator allocates new areas top-down from below the 1349 * stack's low limit (the base): 1350 */ 1351 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1352 unsigned long 1353 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1354 const unsigned long len, const unsigned long pgoff, 1355 const unsigned long flags) 1356 { 1357 struct vm_area_struct *vma; 1358 struct mm_struct *mm = current->mm; 1359 unsigned long addr = addr0; 1360 1361 /* requested length too big for entire address space */ 1362 if (len > TASK_SIZE) 1363 return -ENOMEM; 1364 1365 if (flags & MAP_FIXED) 1366 return addr; 1367 1368 /* requesting a specific address */ 1369 if (addr) { 1370 addr = PAGE_ALIGN(addr); 1371 vma = find_vma(mm, addr); 1372 if (TASK_SIZE - len >= addr && 1373 (!vma || addr + len <= vma->vm_start)) 1374 return addr; 1375 } 1376 1377 /* check if free_area_cache is useful for us */ 1378 if (len <= mm->cached_hole_size) { 1379 mm->cached_hole_size = 0; 1380 mm->free_area_cache = mm->mmap_base; 1381 } 1382 1383 /* either no address requested or can't fit in requested address hole */ 1384 addr = mm->free_area_cache; 1385 1386 /* make sure it can fit in the remaining address space */ 1387 if (addr > len) { 1388 vma = find_vma(mm, addr-len); 1389 if (!vma || addr <= vma->vm_start) 1390 /* remember the address as a hint for next time */ 1391 return (mm->free_area_cache = addr-len); 1392 } 1393 1394 if (mm->mmap_base < len) 1395 goto bottomup; 1396 1397 addr = mm->mmap_base-len; 1398 1399 do { 1400 /* 1401 * Lookup failure means no vma is above this address, 1402 * else if new region fits below vma->vm_start, 1403 * return with success: 1404 */ 1405 vma = find_vma(mm, addr); 1406 if (!vma || addr+len <= vma->vm_start) 1407 /* remember the address as a hint for next time */ 1408 return (mm->free_area_cache = addr); 1409 1410 /* remember the largest hole we saw so far */ 1411 if (addr + mm->cached_hole_size < vma->vm_start) 1412 mm->cached_hole_size = vma->vm_start - addr; 1413 1414 /* try just below the current vma->vm_start */ 1415 addr = vma->vm_start-len; 1416 } while (len < vma->vm_start); 1417 1418 bottomup: 1419 /* 1420 * A failed mmap() very likely causes application failure, 1421 * so fall back to the bottom-up function here. This scenario 1422 * can happen with large stack limits and large mmap() 1423 * allocations. 1424 */ 1425 mm->cached_hole_size = ~0UL; 1426 mm->free_area_cache = TASK_UNMAPPED_BASE; 1427 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1428 /* 1429 * Restore the topdown base: 1430 */ 1431 mm->free_area_cache = mm->mmap_base; 1432 mm->cached_hole_size = ~0UL; 1433 1434 return addr; 1435 } 1436 #endif 1437 1438 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1439 { 1440 /* 1441 * Is this a new hole at the highest possible address? 1442 */ 1443 if (addr > mm->free_area_cache) 1444 mm->free_area_cache = addr; 1445 1446 /* dont allow allocations above current base */ 1447 if (mm->free_area_cache > mm->mmap_base) 1448 mm->free_area_cache = mm->mmap_base; 1449 } 1450 1451 unsigned long 1452 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1453 unsigned long pgoff, unsigned long flags) 1454 { 1455 unsigned long (*get_area)(struct file *, unsigned long, 1456 unsigned long, unsigned long, unsigned long); 1457 1458 get_area = current->mm->get_unmapped_area; 1459 if (file && file->f_op && file->f_op->get_unmapped_area) 1460 get_area = file->f_op->get_unmapped_area; 1461 addr = get_area(file, addr, len, pgoff, flags); 1462 if (IS_ERR_VALUE(addr)) 1463 return addr; 1464 1465 if (addr > TASK_SIZE - len) 1466 return -ENOMEM; 1467 if (addr & ~PAGE_MASK) 1468 return -EINVAL; 1469 1470 return arch_rebalance_pgtables(addr, len); 1471 } 1472 1473 EXPORT_SYMBOL(get_unmapped_area); 1474 1475 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1476 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 1477 { 1478 struct vm_area_struct *vma = NULL; 1479 1480 if (mm) { 1481 /* Check the cache first. */ 1482 /* (Cache hit rate is typically around 35%.) */ 1483 vma = mm->mmap_cache; 1484 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1485 struct rb_node * rb_node; 1486 1487 rb_node = mm->mm_rb.rb_node; 1488 vma = NULL; 1489 1490 while (rb_node) { 1491 struct vm_area_struct * vma_tmp; 1492 1493 vma_tmp = rb_entry(rb_node, 1494 struct vm_area_struct, vm_rb); 1495 1496 if (vma_tmp->vm_end > addr) { 1497 vma = vma_tmp; 1498 if (vma_tmp->vm_start <= addr) 1499 break; 1500 rb_node = rb_node->rb_left; 1501 } else 1502 rb_node = rb_node->rb_right; 1503 } 1504 if (vma) 1505 mm->mmap_cache = vma; 1506 } 1507 } 1508 return vma; 1509 } 1510 1511 EXPORT_SYMBOL(find_vma); 1512 1513 /* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1514 struct vm_area_struct * 1515 find_vma_prev(struct mm_struct *mm, unsigned long addr, 1516 struct vm_area_struct **pprev) 1517 { 1518 struct vm_area_struct *vma = NULL, *prev = NULL; 1519 struct rb_node *rb_node; 1520 if (!mm) 1521 goto out; 1522 1523 /* Guard against addr being lower than the first VMA */ 1524 vma = mm->mmap; 1525 1526 /* Go through the RB tree quickly. */ 1527 rb_node = mm->mm_rb.rb_node; 1528 1529 while (rb_node) { 1530 struct vm_area_struct *vma_tmp; 1531 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1532 1533 if (addr < vma_tmp->vm_end) { 1534 rb_node = rb_node->rb_left; 1535 } else { 1536 prev = vma_tmp; 1537 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1538 break; 1539 rb_node = rb_node->rb_right; 1540 } 1541 } 1542 1543 out: 1544 *pprev = prev; 1545 return prev ? prev->vm_next : vma; 1546 } 1547 1548 /* 1549 * Verify that the stack growth is acceptable and 1550 * update accounting. This is shared with both the 1551 * grow-up and grow-down cases. 1552 */ 1553 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) 1554 { 1555 struct mm_struct *mm = vma->vm_mm; 1556 struct rlimit *rlim = current->signal->rlim; 1557 unsigned long new_start; 1558 1559 /* address space limit tests */ 1560 if (!may_expand_vm(mm, grow)) 1561 return -ENOMEM; 1562 1563 /* Stack limit test */ 1564 if (size > rlim[RLIMIT_STACK].rlim_cur) 1565 return -ENOMEM; 1566 1567 /* mlock limit tests */ 1568 if (vma->vm_flags & VM_LOCKED) { 1569 unsigned long locked; 1570 unsigned long limit; 1571 locked = mm->locked_vm + grow; 1572 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1573 if (locked > limit && !capable(CAP_IPC_LOCK)) 1574 return -ENOMEM; 1575 } 1576 1577 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1578 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1579 vma->vm_end - size; 1580 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1581 return -EFAULT; 1582 1583 /* 1584 * Overcommit.. This must be the final test, as it will 1585 * update security statistics. 1586 */ 1587 if (security_vm_enough_memory_mm(mm, grow)) 1588 return -ENOMEM; 1589 1590 /* Ok, everything looks good - let it rip */ 1591 mm->total_vm += grow; 1592 if (vma->vm_flags & VM_LOCKED) 1593 mm->locked_vm += grow; 1594 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1595 return 0; 1596 } 1597 1598 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1599 /* 1600 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1601 * vma is the last one with address > vma->vm_end. Have to extend vma. 1602 */ 1603 #ifndef CONFIG_IA64 1604 static 1605 #endif 1606 int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1607 { 1608 int error; 1609 1610 if (!(vma->vm_flags & VM_GROWSUP)) 1611 return -EFAULT; 1612 1613 /* 1614 * We must make sure the anon_vma is allocated 1615 * so that the anon_vma locking is not a noop. 1616 */ 1617 if (unlikely(anon_vma_prepare(vma))) 1618 return -ENOMEM; 1619 anon_vma_lock(vma); 1620 1621 /* 1622 * vma->vm_start/vm_end cannot change under us because the caller 1623 * is required to hold the mmap_sem in read mode. We need the 1624 * anon_vma lock to serialize against concurrent expand_stacks. 1625 * Also guard against wrapping around to address 0. 1626 */ 1627 if (address < PAGE_ALIGN(address+4)) 1628 address = PAGE_ALIGN(address+4); 1629 else { 1630 anon_vma_unlock(vma); 1631 return -ENOMEM; 1632 } 1633 error = 0; 1634 1635 /* Somebody else might have raced and expanded it already */ 1636 if (address > vma->vm_end) { 1637 unsigned long size, grow; 1638 1639 size = address - vma->vm_start; 1640 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1641 1642 error = acct_stack_growth(vma, size, grow); 1643 if (!error) 1644 vma->vm_end = address; 1645 } 1646 anon_vma_unlock(vma); 1647 return error; 1648 } 1649 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1650 1651 /* 1652 * vma is the first one with address < vma->vm_start. Have to extend vma. 1653 */ 1654 static int expand_downwards(struct vm_area_struct *vma, 1655 unsigned long address) 1656 { 1657 int error; 1658 1659 /* 1660 * We must make sure the anon_vma is allocated 1661 * so that the anon_vma locking is not a noop. 1662 */ 1663 if (unlikely(anon_vma_prepare(vma))) 1664 return -ENOMEM; 1665 1666 address &= PAGE_MASK; 1667 error = security_file_mmap(NULL, 0, 0, 0, address, 1); 1668 if (error) 1669 return error; 1670 1671 anon_vma_lock(vma); 1672 1673 /* 1674 * vma->vm_start/vm_end cannot change under us because the caller 1675 * is required to hold the mmap_sem in read mode. We need the 1676 * anon_vma lock to serialize against concurrent expand_stacks. 1677 */ 1678 1679 /* Somebody else might have raced and expanded it already */ 1680 if (address < vma->vm_start) { 1681 unsigned long size, grow; 1682 1683 size = vma->vm_end - address; 1684 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1685 1686 error = acct_stack_growth(vma, size, grow); 1687 if (!error) { 1688 vma->vm_start = address; 1689 vma->vm_pgoff -= grow; 1690 } 1691 } 1692 anon_vma_unlock(vma); 1693 return error; 1694 } 1695 1696 int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) 1697 { 1698 return expand_downwards(vma, address); 1699 } 1700 1701 #ifdef CONFIG_STACK_GROWSUP 1702 int expand_stack(struct vm_area_struct *vma, unsigned long address) 1703 { 1704 return expand_upwards(vma, address); 1705 } 1706 1707 struct vm_area_struct * 1708 find_extend_vma(struct mm_struct *mm, unsigned long addr) 1709 { 1710 struct vm_area_struct *vma, *prev; 1711 1712 addr &= PAGE_MASK; 1713 vma = find_vma_prev(mm, addr, &prev); 1714 if (vma && (vma->vm_start <= addr)) 1715 return vma; 1716 if (!prev || expand_stack(prev, addr)) 1717 return NULL; 1718 if (prev->vm_flags & VM_LOCKED) { 1719 if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0) 1720 return NULL; /* vma gone! */ 1721 } 1722 return prev; 1723 } 1724 #else 1725 int expand_stack(struct vm_area_struct *vma, unsigned long address) 1726 { 1727 return expand_downwards(vma, address); 1728 } 1729 1730 struct vm_area_struct * 1731 find_extend_vma(struct mm_struct * mm, unsigned long addr) 1732 { 1733 struct vm_area_struct * vma; 1734 unsigned long start; 1735 1736 addr &= PAGE_MASK; 1737 vma = find_vma(mm,addr); 1738 if (!vma) 1739 return NULL; 1740 if (vma->vm_start <= addr) 1741 return vma; 1742 if (!(vma->vm_flags & VM_GROWSDOWN)) 1743 return NULL; 1744 start = vma->vm_start; 1745 if (expand_stack(vma, addr)) 1746 return NULL; 1747 if (vma->vm_flags & VM_LOCKED) { 1748 if (mlock_vma_pages_range(vma, addr, start) < 0) 1749 return NULL; /* vma gone! */ 1750 } 1751 return vma; 1752 } 1753 #endif 1754 1755 /* 1756 * Ok - we have the memory areas we should free on the vma list, 1757 * so release them, and do the vma updates. 1758 * 1759 * Called with the mm semaphore held. 1760 */ 1761 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1762 { 1763 /* Update high watermark before we lower total_vm */ 1764 update_hiwater_vm(mm); 1765 do { 1766 long nrpages = vma_pages(vma); 1767 1768 mm->total_vm -= nrpages; 1769 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1770 vma = remove_vma(vma); 1771 } while (vma); 1772 validate_mm(mm); 1773 } 1774 1775 /* 1776 * Get rid of page table information in the indicated region. 1777 * 1778 * Called with the mm semaphore held. 1779 */ 1780 static void unmap_region(struct mm_struct *mm, 1781 struct vm_area_struct *vma, struct vm_area_struct *prev, 1782 unsigned long start, unsigned long end) 1783 { 1784 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1785 struct mmu_gather *tlb; 1786 unsigned long nr_accounted = 0; 1787 1788 lru_add_drain(); 1789 tlb = tlb_gather_mmu(mm, 0); 1790 update_hiwater_rss(mm); 1791 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1792 vm_unacct_memory(nr_accounted); 1793 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1794 next? next->vm_start: 0); 1795 tlb_finish_mmu(tlb, start, end); 1796 } 1797 1798 /* 1799 * Create a list of vma's touched by the unmap, removing them from the mm's 1800 * vma list as we go.. 1801 */ 1802 static void 1803 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1804 struct vm_area_struct *prev, unsigned long end) 1805 { 1806 struct vm_area_struct **insertion_point; 1807 struct vm_area_struct *tail_vma = NULL; 1808 unsigned long addr; 1809 1810 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1811 do { 1812 rb_erase(&vma->vm_rb, &mm->mm_rb); 1813 mm->map_count--; 1814 tail_vma = vma; 1815 vma = vma->vm_next; 1816 } while (vma && vma->vm_start < end); 1817 *insertion_point = vma; 1818 tail_vma->vm_next = NULL; 1819 if (mm->unmap_area == arch_unmap_area) 1820 addr = prev ? prev->vm_end : mm->mmap_base; 1821 else 1822 addr = vma ? vma->vm_start : mm->mmap_base; 1823 mm->unmap_area(mm, addr); 1824 mm->mmap_cache = NULL; /* Kill the cache. */ 1825 } 1826 1827 /* 1828 * Split a vma into two pieces at address 'addr', a new vma is allocated 1829 * either for the first part or the tail. 1830 */ 1831 int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1832 unsigned long addr, int new_below) 1833 { 1834 struct mempolicy *pol; 1835 struct vm_area_struct *new; 1836 1837 if (is_vm_hugetlb_page(vma) && (addr & 1838 ~(huge_page_mask(hstate_vma(vma))))) 1839 return -EINVAL; 1840 1841 if (mm->map_count >= sysctl_max_map_count) 1842 return -ENOMEM; 1843 1844 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1845 if (!new) 1846 return -ENOMEM; 1847 1848 /* most fields are the same, copy all, and then fixup */ 1849 *new = *vma; 1850 1851 if (new_below) 1852 new->vm_end = addr; 1853 else { 1854 new->vm_start = addr; 1855 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1856 } 1857 1858 pol = mpol_dup(vma_policy(vma)); 1859 if (IS_ERR(pol)) { 1860 kmem_cache_free(vm_area_cachep, new); 1861 return PTR_ERR(pol); 1862 } 1863 vma_set_policy(new, pol); 1864 1865 if (new->vm_file) { 1866 get_file(new->vm_file); 1867 if (vma->vm_flags & VM_EXECUTABLE) 1868 added_exe_file_vma(mm); 1869 } 1870 1871 if (new->vm_ops && new->vm_ops->open) 1872 new->vm_ops->open(new); 1873 1874 if (new_below) 1875 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1876 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1877 else 1878 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1879 1880 return 0; 1881 } 1882 1883 /* Munmap is split into 2 main parts -- this part which finds 1884 * what needs doing, and the areas themselves, which do the 1885 * work. This now handles partial unmappings. 1886 * Jeremy Fitzhardinge <jeremy@goop.org> 1887 */ 1888 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1889 { 1890 unsigned long end; 1891 struct vm_area_struct *vma, *prev, *last; 1892 1893 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1894 return -EINVAL; 1895 1896 if ((len = PAGE_ALIGN(len)) == 0) 1897 return -EINVAL; 1898 1899 /* Find the first overlapping VMA */ 1900 vma = find_vma_prev(mm, start, &prev); 1901 if (!vma) 1902 return 0; 1903 /* we have start < vma->vm_end */ 1904 1905 /* if it doesn't overlap, we have nothing.. */ 1906 end = start + len; 1907 if (vma->vm_start >= end) 1908 return 0; 1909 1910 /* 1911 * If we need to split any vma, do it now to save pain later. 1912 * 1913 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1914 * unmapped vm_area_struct will remain in use: so lower split_vma 1915 * places tmp vma above, and higher split_vma places tmp vma below. 1916 */ 1917 if (start > vma->vm_start) { 1918 int error = split_vma(mm, vma, start, 0); 1919 if (error) 1920 return error; 1921 prev = vma; 1922 } 1923 1924 /* Does it split the last one? */ 1925 last = find_vma(mm, end); 1926 if (last && end > last->vm_start) { 1927 int error = split_vma(mm, last, end, 1); 1928 if (error) 1929 return error; 1930 } 1931 vma = prev? prev->vm_next: mm->mmap; 1932 1933 /* 1934 * unlock any mlock()ed ranges before detaching vmas 1935 */ 1936 if (mm->locked_vm) { 1937 struct vm_area_struct *tmp = vma; 1938 while (tmp && tmp->vm_start < end) { 1939 if (tmp->vm_flags & VM_LOCKED) { 1940 mm->locked_vm -= vma_pages(tmp); 1941 munlock_vma_pages_all(tmp); 1942 } 1943 tmp = tmp->vm_next; 1944 } 1945 } 1946 1947 /* 1948 * Remove the vma's, and unmap the actual pages 1949 */ 1950 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1951 unmap_region(mm, vma, prev, start, end); 1952 1953 /* Fix up all other VM information */ 1954 remove_vma_list(mm, vma); 1955 1956 return 0; 1957 } 1958 1959 EXPORT_SYMBOL(do_munmap); 1960 1961 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1962 { 1963 int ret; 1964 struct mm_struct *mm = current->mm; 1965 1966 profile_munmap(addr); 1967 1968 down_write(&mm->mmap_sem); 1969 ret = do_munmap(mm, addr, len); 1970 up_write(&mm->mmap_sem); 1971 return ret; 1972 } 1973 1974 static inline void verify_mm_writelocked(struct mm_struct *mm) 1975 { 1976 #ifdef CONFIG_DEBUG_VM 1977 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1978 WARN_ON(1); 1979 up_read(&mm->mmap_sem); 1980 } 1981 #endif 1982 } 1983 1984 /* 1985 * this is really a simplified "do_mmap". it only handles 1986 * anonymous maps. eventually we may be able to do some 1987 * brk-specific accounting here. 1988 */ 1989 unsigned long do_brk(unsigned long addr, unsigned long len) 1990 { 1991 struct mm_struct * mm = current->mm; 1992 struct vm_area_struct * vma, * prev; 1993 unsigned long flags; 1994 struct rb_node ** rb_link, * rb_parent; 1995 pgoff_t pgoff = addr >> PAGE_SHIFT; 1996 int error; 1997 1998 len = PAGE_ALIGN(len); 1999 if (!len) 2000 return addr; 2001 2002 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 2003 return -EINVAL; 2004 2005 if (is_hugepage_only_range(mm, addr, len)) 2006 return -EINVAL; 2007 2008 error = security_file_mmap(NULL, 0, 0, 0, addr, 1); 2009 if (error) 2010 return error; 2011 2012 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 2013 2014 error = arch_mmap_check(addr, len, flags); 2015 if (error) 2016 return error; 2017 2018 /* 2019 * mlock MCL_FUTURE? 2020 */ 2021 if (mm->def_flags & VM_LOCKED) { 2022 unsigned long locked, lock_limit; 2023 locked = len >> PAGE_SHIFT; 2024 locked += mm->locked_vm; 2025 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 2026 lock_limit >>= PAGE_SHIFT; 2027 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 2028 return -EAGAIN; 2029 } 2030 2031 /* 2032 * mm->mmap_sem is required to protect against another thread 2033 * changing the mappings in case we sleep. 2034 */ 2035 verify_mm_writelocked(mm); 2036 2037 /* 2038 * Clear old maps. this also does some error checking for us 2039 */ 2040 munmap_back: 2041 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2042 if (vma && vma->vm_start < addr + len) { 2043 if (do_munmap(mm, addr, len)) 2044 return -ENOMEM; 2045 goto munmap_back; 2046 } 2047 2048 /* Check against address space limits *after* clearing old maps... */ 2049 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 2050 return -ENOMEM; 2051 2052 if (mm->map_count > sysctl_max_map_count) 2053 return -ENOMEM; 2054 2055 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 2056 return -ENOMEM; 2057 2058 /* Can we just expand an old private anonymous mapping? */ 2059 vma = vma_merge(mm, prev, addr, addr + len, flags, 2060 NULL, NULL, pgoff, NULL); 2061 if (vma) 2062 goto out; 2063 2064 /* 2065 * create a vma struct for an anonymous mapping 2066 */ 2067 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2068 if (!vma) { 2069 vm_unacct_memory(len >> PAGE_SHIFT); 2070 return -ENOMEM; 2071 } 2072 2073 vma->vm_mm = mm; 2074 vma->vm_start = addr; 2075 vma->vm_end = addr + len; 2076 vma->vm_pgoff = pgoff; 2077 vma->vm_flags = flags; 2078 vma->vm_page_prot = vm_get_page_prot(flags); 2079 vma_link(mm, vma, prev, rb_link, rb_parent); 2080 out: 2081 mm->total_vm += len >> PAGE_SHIFT; 2082 if (flags & VM_LOCKED) { 2083 if (!mlock_vma_pages_range(vma, addr, addr + len)) 2084 mm->locked_vm += (len >> PAGE_SHIFT); 2085 } 2086 return addr; 2087 } 2088 2089 EXPORT_SYMBOL(do_brk); 2090 2091 /* Release all mmaps. */ 2092 void exit_mmap(struct mm_struct *mm) 2093 { 2094 struct mmu_gather *tlb; 2095 struct vm_area_struct *vma; 2096 unsigned long nr_accounted = 0; 2097 unsigned long end; 2098 2099 /* mm's last user has gone, and its about to be pulled down */ 2100 mmu_notifier_release(mm); 2101 2102 if (mm->locked_vm) { 2103 vma = mm->mmap; 2104 while (vma) { 2105 if (vma->vm_flags & VM_LOCKED) 2106 munlock_vma_pages_all(vma); 2107 vma = vma->vm_next; 2108 } 2109 } 2110 2111 arch_exit_mmap(mm); 2112 2113 vma = mm->mmap; 2114 if (!vma) /* Can happen if dup_mmap() received an OOM */ 2115 return; 2116 2117 lru_add_drain(); 2118 flush_cache_mm(mm); 2119 tlb = tlb_gather_mmu(mm, 1); 2120 /* update_hiwater_rss(mm) here? but nobody should be looking */ 2121 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2122 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 2123 vm_unacct_memory(nr_accounted); 2124 2125 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); 2126 tlb_finish_mmu(tlb, 0, end); 2127 2128 /* 2129 * Walk the list again, actually closing and freeing it, 2130 * with preemption enabled, without holding any MM locks. 2131 */ 2132 while (vma) 2133 vma = remove_vma(vma); 2134 2135 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2136 } 2137 2138 /* Insert vm structure into process list sorted by address 2139 * and into the inode's i_mmap tree. If vm_file is non-NULL 2140 * then i_mmap_lock is taken here. 2141 */ 2142 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 2143 { 2144 struct vm_area_struct * __vma, * prev; 2145 struct rb_node ** rb_link, * rb_parent; 2146 2147 /* 2148 * The vm_pgoff of a purely anonymous vma should be irrelevant 2149 * until its first write fault, when page's anon_vma and index 2150 * are set. But now set the vm_pgoff it will almost certainly 2151 * end up with (unless mremap moves it elsewhere before that 2152 * first wfault), so /proc/pid/maps tells a consistent story. 2153 * 2154 * By setting it to reflect the virtual start address of the 2155 * vma, merges and splits can happen in a seamless way, just 2156 * using the existing file pgoff checks and manipulations. 2157 * Similarly in do_mmap_pgoff and in do_brk. 2158 */ 2159 if (!vma->vm_file) { 2160 BUG_ON(vma->anon_vma); 2161 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2162 } 2163 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2164 if (__vma && __vma->vm_start < vma->vm_end) 2165 return -ENOMEM; 2166 if ((vma->vm_flags & VM_ACCOUNT) && 2167 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2168 return -ENOMEM; 2169 vma_link(mm, vma, prev, rb_link, rb_parent); 2170 return 0; 2171 } 2172 2173 /* 2174 * Copy the vma structure to a new location in the same mm, 2175 * prior to moving page table entries, to effect an mremap move. 2176 */ 2177 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2178 unsigned long addr, unsigned long len, pgoff_t pgoff) 2179 { 2180 struct vm_area_struct *vma = *vmap; 2181 unsigned long vma_start = vma->vm_start; 2182 struct mm_struct *mm = vma->vm_mm; 2183 struct vm_area_struct *new_vma, *prev; 2184 struct rb_node **rb_link, *rb_parent; 2185 struct mempolicy *pol; 2186 2187 /* 2188 * If anonymous vma has not yet been faulted, update new pgoff 2189 * to match new location, to increase its chance of merging. 2190 */ 2191 if (!vma->vm_file && !vma->anon_vma) 2192 pgoff = addr >> PAGE_SHIFT; 2193 2194 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2195 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2196 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2197 if (new_vma) { 2198 /* 2199 * Source vma may have been merged into new_vma 2200 */ 2201 if (vma_start >= new_vma->vm_start && 2202 vma_start < new_vma->vm_end) 2203 *vmap = new_vma; 2204 } else { 2205 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2206 if (new_vma) { 2207 *new_vma = *vma; 2208 pol = mpol_dup(vma_policy(vma)); 2209 if (IS_ERR(pol)) { 2210 kmem_cache_free(vm_area_cachep, new_vma); 2211 return NULL; 2212 } 2213 vma_set_policy(new_vma, pol); 2214 new_vma->vm_start = addr; 2215 new_vma->vm_end = addr + len; 2216 new_vma->vm_pgoff = pgoff; 2217 if (new_vma->vm_file) { 2218 get_file(new_vma->vm_file); 2219 if (vma->vm_flags & VM_EXECUTABLE) 2220 added_exe_file_vma(mm); 2221 } 2222 if (new_vma->vm_ops && new_vma->vm_ops->open) 2223 new_vma->vm_ops->open(new_vma); 2224 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2225 } 2226 } 2227 return new_vma; 2228 } 2229 2230 /* 2231 * Return true if the calling process may expand its vm space by the passed 2232 * number of pages 2233 */ 2234 int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2235 { 2236 unsigned long cur = mm->total_vm; /* pages */ 2237 unsigned long lim; 2238 2239 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2240 2241 if (cur + npages > lim) 2242 return 0; 2243 return 1; 2244 } 2245 2246 2247 static int special_mapping_fault(struct vm_area_struct *vma, 2248 struct vm_fault *vmf) 2249 { 2250 pgoff_t pgoff; 2251 struct page **pages; 2252 2253 /* 2254 * special mappings have no vm_file, and in that case, the mm 2255 * uses vm_pgoff internally. So we have to subtract it from here. 2256 * We are allowed to do this because we are the mm; do not copy 2257 * this code into drivers! 2258 */ 2259 pgoff = vmf->pgoff - vma->vm_pgoff; 2260 2261 for (pages = vma->vm_private_data; pgoff && *pages; ++pages) 2262 pgoff--; 2263 2264 if (*pages) { 2265 struct page *page = *pages; 2266 get_page(page); 2267 vmf->page = page; 2268 return 0; 2269 } 2270 2271 return VM_FAULT_SIGBUS; 2272 } 2273 2274 /* 2275 * Having a close hook prevents vma merging regardless of flags. 2276 */ 2277 static void special_mapping_close(struct vm_area_struct *vma) 2278 { 2279 } 2280 2281 static const struct vm_operations_struct special_mapping_vmops = { 2282 .close = special_mapping_close, 2283 .fault = special_mapping_fault, 2284 }; 2285 2286 /* 2287 * Called with mm->mmap_sem held for writing. 2288 * Insert a new vma covering the given region, with the given flags. 2289 * Its pages are supplied by the given array of struct page *. 2290 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2291 * The region past the last page supplied will always produce SIGBUS. 2292 * The array pointer and the pages it points to are assumed to stay alive 2293 * for as long as this mapping might exist. 2294 */ 2295 int install_special_mapping(struct mm_struct *mm, 2296 unsigned long addr, unsigned long len, 2297 unsigned long vm_flags, struct page **pages) 2298 { 2299 struct vm_area_struct *vma; 2300 2301 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2302 if (unlikely(vma == NULL)) 2303 return -ENOMEM; 2304 2305 vma->vm_mm = mm; 2306 vma->vm_start = addr; 2307 vma->vm_end = addr + len; 2308 2309 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; 2310 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 2311 2312 vma->vm_ops = &special_mapping_vmops; 2313 vma->vm_private_data = pages; 2314 2315 if (unlikely(insert_vm_struct(mm, vma))) { 2316 kmem_cache_free(vm_area_cachep, vma); 2317 return -ENOMEM; 2318 } 2319 2320 mm->total_vm += len >> PAGE_SHIFT; 2321 2322 perf_event_mmap(vma); 2323 2324 return 0; 2325 } 2326 2327 static DEFINE_MUTEX(mm_all_locks_mutex); 2328 2329 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) 2330 { 2331 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2332 /* 2333 * The LSB of head.next can't change from under us 2334 * because we hold the mm_all_locks_mutex. 2335 */ 2336 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem); 2337 /* 2338 * We can safely modify head.next after taking the 2339 * anon_vma->lock. If some other vma in this mm shares 2340 * the same anon_vma we won't take it again. 2341 * 2342 * No need of atomic instructions here, head.next 2343 * can't change from under us thanks to the 2344 * anon_vma->lock. 2345 */ 2346 if (__test_and_set_bit(0, (unsigned long *) 2347 &anon_vma->head.next)) 2348 BUG(); 2349 } 2350 } 2351 2352 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) 2353 { 2354 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2355 /* 2356 * AS_MM_ALL_LOCKS can't change from under us because 2357 * we hold the mm_all_locks_mutex. 2358 * 2359 * Operations on ->flags have to be atomic because 2360 * even if AS_MM_ALL_LOCKS is stable thanks to the 2361 * mm_all_locks_mutex, there may be other cpus 2362 * changing other bitflags in parallel to us. 2363 */ 2364 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) 2365 BUG(); 2366 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem); 2367 } 2368 } 2369 2370 /* 2371 * This operation locks against the VM for all pte/vma/mm related 2372 * operations that could ever happen on a certain mm. This includes 2373 * vmtruncate, try_to_unmap, and all page faults. 2374 * 2375 * The caller must take the mmap_sem in write mode before calling 2376 * mm_take_all_locks(). The caller isn't allowed to release the 2377 * mmap_sem until mm_drop_all_locks() returns. 2378 * 2379 * mmap_sem in write mode is required in order to block all operations 2380 * that could modify pagetables and free pages without need of 2381 * altering the vma layout (for example populate_range() with 2382 * nonlinear vmas). It's also needed in write mode to avoid new 2383 * anon_vmas to be associated with existing vmas. 2384 * 2385 * A single task can't take more than one mm_take_all_locks() in a row 2386 * or it would deadlock. 2387 * 2388 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in 2389 * mapping->flags avoid to take the same lock twice, if more than one 2390 * vma in this mm is backed by the same anon_vma or address_space. 2391 * 2392 * We can take all the locks in random order because the VM code 2393 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never 2394 * takes more than one of them in a row. Secondly we're protected 2395 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. 2396 * 2397 * mm_take_all_locks() and mm_drop_all_locks are expensive operations 2398 * that may have to take thousand of locks. 2399 * 2400 * mm_take_all_locks() can fail if it's interrupted by signals. 2401 */ 2402 int mm_take_all_locks(struct mm_struct *mm) 2403 { 2404 struct vm_area_struct *vma; 2405 int ret = -EINTR; 2406 2407 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2408 2409 mutex_lock(&mm_all_locks_mutex); 2410 2411 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2412 if (signal_pending(current)) 2413 goto out_unlock; 2414 if (vma->vm_file && vma->vm_file->f_mapping) 2415 vm_lock_mapping(mm, vma->vm_file->f_mapping); 2416 } 2417 2418 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2419 if (signal_pending(current)) 2420 goto out_unlock; 2421 if (vma->anon_vma) 2422 vm_lock_anon_vma(mm, vma->anon_vma); 2423 } 2424 2425 ret = 0; 2426 2427 out_unlock: 2428 if (ret) 2429 mm_drop_all_locks(mm); 2430 2431 return ret; 2432 } 2433 2434 static void vm_unlock_anon_vma(struct anon_vma *anon_vma) 2435 { 2436 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2437 /* 2438 * The LSB of head.next can't change to 0 from under 2439 * us because we hold the mm_all_locks_mutex. 2440 * 2441 * We must however clear the bitflag before unlocking 2442 * the vma so the users using the anon_vma->head will 2443 * never see our bitflag. 2444 * 2445 * No need of atomic instructions here, head.next 2446 * can't change from under us until we release the 2447 * anon_vma->lock. 2448 */ 2449 if (!__test_and_clear_bit(0, (unsigned long *) 2450 &anon_vma->head.next)) 2451 BUG(); 2452 spin_unlock(&anon_vma->lock); 2453 } 2454 } 2455 2456 static void vm_unlock_mapping(struct address_space *mapping) 2457 { 2458 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2459 /* 2460 * AS_MM_ALL_LOCKS can't change to 0 from under us 2461 * because we hold the mm_all_locks_mutex. 2462 */ 2463 spin_unlock(&mapping->i_mmap_lock); 2464 if (!test_and_clear_bit(AS_MM_ALL_LOCKS, 2465 &mapping->flags)) 2466 BUG(); 2467 } 2468 } 2469 2470 /* 2471 * The mmap_sem cannot be released by the caller until 2472 * mm_drop_all_locks() returns. 2473 */ 2474 void mm_drop_all_locks(struct mm_struct *mm) 2475 { 2476 struct vm_area_struct *vma; 2477 2478 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2479 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); 2480 2481 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2482 if (vma->anon_vma) 2483 vm_unlock_anon_vma(vma->anon_vma); 2484 if (vma->vm_file && vma->vm_file->f_mapping) 2485 vm_unlock_mapping(vma->vm_file->f_mapping); 2486 } 2487 2488 mutex_unlock(&mm_all_locks_mutex); 2489 } 2490 2491 /* 2492 * initialise the VMA slab 2493 */ 2494 void __init mmap_init(void) 2495 { 2496 int ret; 2497 2498 ret = percpu_counter_init(&vm_committed_as, 0); 2499 VM_BUG_ON(ret); 2500 } 2501