mmap.c revision 7cd5a02f54f4c9d16cf7fdffa2122bc73bb09b43
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/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 31#include <asm/uaccess.h> 32#include <asm/cacheflush.h> 33#include <asm/tlb.h> 34#include <asm/mmu_context.h> 35 36#include "internal.h" 37 38#ifndef arch_mmap_check 39#define arch_mmap_check(addr, len, flags) (0) 40#endif 41 42#ifndef arch_rebalance_pgtables 43#define arch_rebalance_pgtables(addr, len) (addr) 44#endif 45 46static void unmap_region(struct mm_struct *mm, 47 struct vm_area_struct *vma, struct vm_area_struct *prev, 48 unsigned long start, unsigned long end); 49 50/* 51 * WARNING: the debugging will use recursive algorithms so never enable this 52 * unless you know what you are doing. 53 */ 54#undef DEBUG_MM_RB 55 56/* description of effects of mapping type and prot in current implementation. 57 * this is due to the limited x86 page protection hardware. The expected 58 * behavior is in parens: 59 * 60 * map_type prot 61 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 62 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 63 * w: (no) no w: (no) no w: (yes) yes w: (no) no 64 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 65 * 66 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 67 * w: (no) no w: (no) no w: (copy) copy w: (no) no 68 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 69 * 70 */ 71pgprot_t protection_map[16] = { 72 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 73 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 74}; 75 76pgprot_t vm_get_page_prot(unsigned long vm_flags) 77{ 78 return __pgprot(pgprot_val(protection_map[vm_flags & 79 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | 80 pgprot_val(arch_vm_get_page_prot(vm_flags))); 81} 82EXPORT_SYMBOL(vm_get_page_prot); 83 84int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 85int sysctl_overcommit_ratio = 50; /* default is 50% */ 86int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 87atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0); 88 89/* 90 * Check that a process has enough memory to allocate a new virtual 91 * mapping. 0 means there is enough memory for the allocation to 92 * succeed and -ENOMEM implies there is not. 93 * 94 * We currently support three overcommit policies, which are set via the 95 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 96 * 97 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 98 * Additional code 2002 Jul 20 by Robert Love. 99 * 100 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 101 * 102 * Note this is a helper function intended to be used by LSMs which 103 * wish to use this logic. 104 */ 105int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 106{ 107 unsigned long free, allowed; 108 109 vm_acct_memory(pages); 110 111 /* 112 * Sometimes we want to use more memory than we have 113 */ 114 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 115 return 0; 116 117 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 118 unsigned long n; 119 120 free = global_page_state(NR_FILE_PAGES); 121 free += nr_swap_pages; 122 123 /* 124 * Any slabs which are created with the 125 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 126 * which are reclaimable, under pressure. The dentry 127 * cache and most inode caches should fall into this 128 */ 129 free += global_page_state(NR_SLAB_RECLAIMABLE); 130 131 /* 132 * Leave the last 3% for root 133 */ 134 if (!cap_sys_admin) 135 free -= free / 32; 136 137 if (free > pages) 138 return 0; 139 140 /* 141 * nr_free_pages() is very expensive on large systems, 142 * only call if we're about to fail. 143 */ 144 n = nr_free_pages(); 145 146 /* 147 * Leave reserved pages. The pages are not for anonymous pages. 148 */ 149 if (n <= totalreserve_pages) 150 goto error; 151 else 152 n -= totalreserve_pages; 153 154 /* 155 * Leave the last 3% for root 156 */ 157 if (!cap_sys_admin) 158 n -= n / 32; 159 free += n; 160 161 if (free > pages) 162 return 0; 163 164 goto error; 165 } 166 167 allowed = (totalram_pages - hugetlb_total_pages()) 168 * sysctl_overcommit_ratio / 100; 169 /* 170 * Leave the last 3% for root 171 */ 172 if (!cap_sys_admin) 173 allowed -= allowed / 32; 174 allowed += total_swap_pages; 175 176 /* Don't let a single process grow too big: 177 leave 3% of the size of this process for other processes */ 178 allowed -= mm->total_vm / 32; 179 180 /* 181 * cast `allowed' as a signed long because vm_committed_space 182 * sometimes has a negative value 183 */ 184 if (atomic_long_read(&vm_committed_space) < (long)allowed) 185 return 0; 186error: 187 vm_unacct_memory(pages); 188 189 return -ENOMEM; 190} 191 192/* 193 * Requires inode->i_mapping->i_mmap_lock 194 */ 195static void __remove_shared_vm_struct(struct vm_area_struct *vma, 196 struct file *file, struct address_space *mapping) 197{ 198 if (vma->vm_flags & VM_DENYWRITE) 199 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 200 if (vma->vm_flags & VM_SHARED) 201 mapping->i_mmap_writable--; 202 203 flush_dcache_mmap_lock(mapping); 204 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 205 list_del_init(&vma->shared.vm_set.list); 206 else 207 vma_prio_tree_remove(vma, &mapping->i_mmap); 208 flush_dcache_mmap_unlock(mapping); 209} 210 211/* 212 * Unlink a file-based vm structure from its prio_tree, to hide 213 * vma from rmap and vmtruncate before freeing its page tables. 214 */ 215void unlink_file_vma(struct vm_area_struct *vma) 216{ 217 struct file *file = vma->vm_file; 218 219 if (file) { 220 struct address_space *mapping = file->f_mapping; 221 spin_lock(&mapping->i_mmap_lock); 222 __remove_shared_vm_struct(vma, file, mapping); 223 spin_unlock(&mapping->i_mmap_lock); 224 } 225} 226 227/* 228 * Close a vm structure and free it, returning the next. 229 */ 230static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 231{ 232 struct vm_area_struct *next = vma->vm_next; 233 234 might_sleep(); 235 if (vma->vm_ops && vma->vm_ops->close) 236 vma->vm_ops->close(vma); 237 if (vma->vm_file) { 238 fput(vma->vm_file); 239 if (vma->vm_flags & VM_EXECUTABLE) 240 removed_exe_file_vma(vma->vm_mm); 241 } 242 mpol_put(vma_policy(vma)); 243 kmem_cache_free(vm_area_cachep, vma); 244 return next; 245} 246 247asmlinkage unsigned long sys_brk(unsigned long brk) 248{ 249 unsigned long rlim, retval; 250 unsigned long newbrk, oldbrk; 251 struct mm_struct *mm = current->mm; 252 unsigned long min_brk; 253 254 down_write(&mm->mmap_sem); 255 256#ifdef CONFIG_COMPAT_BRK 257 min_brk = mm->end_code; 258#else 259 min_brk = mm->start_brk; 260#endif 261 if (brk < min_brk) 262 goto out; 263 264 /* 265 * Check against rlimit here. If this check is done later after the test 266 * of oldbrk with newbrk then it can escape the test and let the data 267 * segment grow beyond its set limit the in case where the limit is 268 * not page aligned -Ram Gupta 269 */ 270 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 271 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + 272 (mm->end_data - mm->start_data) > rlim) 273 goto out; 274 275 newbrk = PAGE_ALIGN(brk); 276 oldbrk = PAGE_ALIGN(mm->brk); 277 if (oldbrk == newbrk) 278 goto set_brk; 279 280 /* Always allow shrinking brk. */ 281 if (brk <= mm->brk) { 282 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 283 goto set_brk; 284 goto out; 285 } 286 287 /* Check against existing mmap mappings. */ 288 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 289 goto out; 290 291 /* Ok, looks good - let it rip. */ 292 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 293 goto out; 294set_brk: 295 mm->brk = brk; 296out: 297 retval = mm->brk; 298 up_write(&mm->mmap_sem); 299 return retval; 300} 301 302#ifdef DEBUG_MM_RB 303static int browse_rb(struct rb_root *root) 304{ 305 int i = 0, j; 306 struct rb_node *nd, *pn = NULL; 307 unsigned long prev = 0, pend = 0; 308 309 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 310 struct vm_area_struct *vma; 311 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 312 if (vma->vm_start < prev) 313 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 314 if (vma->vm_start < pend) 315 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 316 if (vma->vm_start > vma->vm_end) 317 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 318 i++; 319 pn = nd; 320 prev = vma->vm_start; 321 pend = vma->vm_end; 322 } 323 j = 0; 324 for (nd = pn; nd; nd = rb_prev(nd)) { 325 j++; 326 } 327 if (i != j) 328 printk("backwards %d, forwards %d\n", j, i), i = 0; 329 return i; 330} 331 332void validate_mm(struct mm_struct *mm) 333{ 334 int bug = 0; 335 int i = 0; 336 struct vm_area_struct *tmp = mm->mmap; 337 while (tmp) { 338 tmp = tmp->vm_next; 339 i++; 340 } 341 if (i != mm->map_count) 342 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 343 i = browse_rb(&mm->mm_rb); 344 if (i != mm->map_count) 345 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 346 BUG_ON(bug); 347} 348#else 349#define validate_mm(mm) do { } while (0) 350#endif 351 352static struct vm_area_struct * 353find_vma_prepare(struct mm_struct *mm, unsigned long addr, 354 struct vm_area_struct **pprev, struct rb_node ***rb_link, 355 struct rb_node ** rb_parent) 356{ 357 struct vm_area_struct * vma; 358 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 359 360 __rb_link = &mm->mm_rb.rb_node; 361 rb_prev = __rb_parent = NULL; 362 vma = NULL; 363 364 while (*__rb_link) { 365 struct vm_area_struct *vma_tmp; 366 367 __rb_parent = *__rb_link; 368 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 369 370 if (vma_tmp->vm_end > addr) { 371 vma = vma_tmp; 372 if (vma_tmp->vm_start <= addr) 373 return vma; 374 __rb_link = &__rb_parent->rb_left; 375 } else { 376 rb_prev = __rb_parent; 377 __rb_link = &__rb_parent->rb_right; 378 } 379 } 380 381 *pprev = NULL; 382 if (rb_prev) 383 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 384 *rb_link = __rb_link; 385 *rb_parent = __rb_parent; 386 return vma; 387} 388 389static inline void 390__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 391 struct vm_area_struct *prev, struct rb_node *rb_parent) 392{ 393 if (prev) { 394 vma->vm_next = prev->vm_next; 395 prev->vm_next = vma; 396 } else { 397 mm->mmap = vma; 398 if (rb_parent) 399 vma->vm_next = rb_entry(rb_parent, 400 struct vm_area_struct, vm_rb); 401 else 402 vma->vm_next = NULL; 403 } 404} 405 406void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 407 struct rb_node **rb_link, struct rb_node *rb_parent) 408{ 409 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 410 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 411} 412 413static inline void __vma_link_file(struct vm_area_struct *vma) 414{ 415 struct file * file; 416 417 file = vma->vm_file; 418 if (file) { 419 struct address_space *mapping = file->f_mapping; 420 421 if (vma->vm_flags & VM_DENYWRITE) 422 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 423 if (vma->vm_flags & VM_SHARED) 424 mapping->i_mmap_writable++; 425 426 flush_dcache_mmap_lock(mapping); 427 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 428 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 429 else 430 vma_prio_tree_insert(vma, &mapping->i_mmap); 431 flush_dcache_mmap_unlock(mapping); 432 } 433} 434 435static void 436__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 437 struct vm_area_struct *prev, struct rb_node **rb_link, 438 struct rb_node *rb_parent) 439{ 440 __vma_link_list(mm, vma, prev, rb_parent); 441 __vma_link_rb(mm, vma, rb_link, rb_parent); 442 __anon_vma_link(vma); 443} 444 445static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 446 struct vm_area_struct *prev, struct rb_node **rb_link, 447 struct rb_node *rb_parent) 448{ 449 struct address_space *mapping = NULL; 450 451 if (vma->vm_file) 452 mapping = vma->vm_file->f_mapping; 453 454 if (mapping) { 455 spin_lock(&mapping->i_mmap_lock); 456 vma->vm_truncate_count = mapping->truncate_count; 457 } 458 anon_vma_lock(vma); 459 460 __vma_link(mm, vma, prev, rb_link, rb_parent); 461 __vma_link_file(vma); 462 463 anon_vma_unlock(vma); 464 if (mapping) 465 spin_unlock(&mapping->i_mmap_lock); 466 467 mm->map_count++; 468 validate_mm(mm); 469} 470 471/* 472 * Helper for vma_adjust in the split_vma insert case: 473 * insert vm structure into list and rbtree and anon_vma, 474 * but it has already been inserted into prio_tree earlier. 475 */ 476static void 477__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 478{ 479 struct vm_area_struct * __vma, * prev; 480 struct rb_node ** rb_link, * rb_parent; 481 482 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 483 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 484 __vma_link(mm, vma, prev, rb_link, rb_parent); 485 mm->map_count++; 486} 487 488static inline void 489__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 490 struct vm_area_struct *prev) 491{ 492 prev->vm_next = vma->vm_next; 493 rb_erase(&vma->vm_rb, &mm->mm_rb); 494 if (mm->mmap_cache == vma) 495 mm->mmap_cache = prev; 496} 497 498/* 499 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 500 * is already present in an i_mmap tree without adjusting the tree. 501 * The following helper function should be used when such adjustments 502 * are necessary. The "insert" vma (if any) is to be inserted 503 * before we drop the necessary locks. 504 */ 505void vma_adjust(struct vm_area_struct *vma, unsigned long start, 506 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 507{ 508 struct mm_struct *mm = vma->vm_mm; 509 struct vm_area_struct *next = vma->vm_next; 510 struct vm_area_struct *importer = NULL; 511 struct address_space *mapping = NULL; 512 struct prio_tree_root *root = NULL; 513 struct file *file = vma->vm_file; 514 struct anon_vma *anon_vma = NULL; 515 long adjust_next = 0; 516 int remove_next = 0; 517 518 if (next && !insert) { 519 if (end >= next->vm_end) { 520 /* 521 * vma expands, overlapping all the next, and 522 * perhaps the one after too (mprotect case 6). 523 */ 524again: remove_next = 1 + (end > next->vm_end); 525 end = next->vm_end; 526 anon_vma = next->anon_vma; 527 importer = vma; 528 } else if (end > next->vm_start) { 529 /* 530 * vma expands, overlapping part of the next: 531 * mprotect case 5 shifting the boundary up. 532 */ 533 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 534 anon_vma = next->anon_vma; 535 importer = vma; 536 } else if (end < vma->vm_end) { 537 /* 538 * vma shrinks, and !insert tells it's not 539 * split_vma inserting another: so it must be 540 * mprotect case 4 shifting the boundary down. 541 */ 542 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 543 anon_vma = next->anon_vma; 544 importer = next; 545 } 546 } 547 548 if (file) { 549 mapping = file->f_mapping; 550 if (!(vma->vm_flags & VM_NONLINEAR)) 551 root = &mapping->i_mmap; 552 spin_lock(&mapping->i_mmap_lock); 553 if (importer && 554 vma->vm_truncate_count != next->vm_truncate_count) { 555 /* 556 * unmap_mapping_range might be in progress: 557 * ensure that the expanding vma is rescanned. 558 */ 559 importer->vm_truncate_count = 0; 560 } 561 if (insert) { 562 insert->vm_truncate_count = vma->vm_truncate_count; 563 /* 564 * Put into prio_tree now, so instantiated pages 565 * are visible to arm/parisc __flush_dcache_page 566 * throughout; but we cannot insert into address 567 * space until vma start or end is updated. 568 */ 569 __vma_link_file(insert); 570 } 571 } 572 573 /* 574 * When changing only vma->vm_end, we don't really need 575 * anon_vma lock: but is that case worth optimizing out? 576 */ 577 if (vma->anon_vma) 578 anon_vma = vma->anon_vma; 579 if (anon_vma) { 580 spin_lock(&anon_vma->lock); 581 /* 582 * Easily overlooked: when mprotect shifts the boundary, 583 * make sure the expanding vma has anon_vma set if the 584 * shrinking vma had, to cover any anon pages imported. 585 */ 586 if (importer && !importer->anon_vma) { 587 importer->anon_vma = anon_vma; 588 __anon_vma_link(importer); 589 } 590 } 591 592 if (root) { 593 flush_dcache_mmap_lock(mapping); 594 vma_prio_tree_remove(vma, root); 595 if (adjust_next) 596 vma_prio_tree_remove(next, root); 597 } 598 599 vma->vm_start = start; 600 vma->vm_end = end; 601 vma->vm_pgoff = pgoff; 602 if (adjust_next) { 603 next->vm_start += adjust_next << PAGE_SHIFT; 604 next->vm_pgoff += adjust_next; 605 } 606 607 if (root) { 608 if (adjust_next) 609 vma_prio_tree_insert(next, root); 610 vma_prio_tree_insert(vma, root); 611 flush_dcache_mmap_unlock(mapping); 612 } 613 614 if (remove_next) { 615 /* 616 * vma_merge has merged next into vma, and needs 617 * us to remove next before dropping the locks. 618 */ 619 __vma_unlink(mm, next, vma); 620 if (file) 621 __remove_shared_vm_struct(next, file, mapping); 622 if (next->anon_vma) 623 __anon_vma_merge(vma, next); 624 } else if (insert) { 625 /* 626 * split_vma has split insert from vma, and needs 627 * us to insert it before dropping the locks 628 * (it may either follow vma or precede it). 629 */ 630 __insert_vm_struct(mm, insert); 631 } 632 633 if (anon_vma) 634 spin_unlock(&anon_vma->lock); 635 if (mapping) 636 spin_unlock(&mapping->i_mmap_lock); 637 638 if (remove_next) { 639 if (file) { 640 fput(file); 641 if (next->vm_flags & VM_EXECUTABLE) 642 removed_exe_file_vma(mm); 643 } 644 mm->map_count--; 645 mpol_put(vma_policy(next)); 646 kmem_cache_free(vm_area_cachep, next); 647 /* 648 * In mprotect's case 6 (see comments on vma_merge), 649 * we must remove another next too. It would clutter 650 * up the code too much to do both in one go. 651 */ 652 if (remove_next == 2) { 653 next = vma->vm_next; 654 goto again; 655 } 656 } 657 658 validate_mm(mm); 659} 660 661/* 662 * If the vma has a ->close operation then the driver probably needs to release 663 * per-vma resources, so we don't attempt to merge those. 664 */ 665#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) 666 667static inline int is_mergeable_vma(struct vm_area_struct *vma, 668 struct file *file, unsigned long vm_flags) 669{ 670 if (vma->vm_flags != vm_flags) 671 return 0; 672 if (vma->vm_file != file) 673 return 0; 674 if (vma->vm_ops && vma->vm_ops->close) 675 return 0; 676 return 1; 677} 678 679static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 680 struct anon_vma *anon_vma2) 681{ 682 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 683} 684 685/* 686 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 687 * in front of (at a lower virtual address and file offset than) the vma. 688 * 689 * We cannot merge two vmas if they have differently assigned (non-NULL) 690 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 691 * 692 * We don't check here for the merged mmap wrapping around the end of pagecache 693 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 694 * wrap, nor mmaps which cover the final page at index -1UL. 695 */ 696static int 697can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 698 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 699{ 700 if (is_mergeable_vma(vma, file, vm_flags) && 701 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 702 if (vma->vm_pgoff == vm_pgoff) 703 return 1; 704 } 705 return 0; 706} 707 708/* 709 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 710 * beyond (at a higher virtual address and file offset than) the vma. 711 * 712 * We cannot merge two vmas if they have differently assigned (non-NULL) 713 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 714 */ 715static int 716can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 717 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 718{ 719 if (is_mergeable_vma(vma, file, vm_flags) && 720 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 721 pgoff_t vm_pglen; 722 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 723 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 724 return 1; 725 } 726 return 0; 727} 728 729/* 730 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 731 * whether that can be merged with its predecessor or its successor. 732 * Or both (it neatly fills a hole). 733 * 734 * In most cases - when called for mmap, brk or mremap - [addr,end) is 735 * certain not to be mapped by the time vma_merge is called; but when 736 * called for mprotect, it is certain to be already mapped (either at 737 * an offset within prev, or at the start of next), and the flags of 738 * this area are about to be changed to vm_flags - and the no-change 739 * case has already been eliminated. 740 * 741 * The following mprotect cases have to be considered, where AAAA is 742 * the area passed down from mprotect_fixup, never extending beyond one 743 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 744 * 745 * AAAA AAAA AAAA AAAA 746 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 747 * cannot merge might become might become might become 748 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 749 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 750 * mremap move: PPPPNNNNNNNN 8 751 * AAAA 752 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 753 * might become case 1 below case 2 below case 3 below 754 * 755 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 756 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 757 */ 758struct vm_area_struct *vma_merge(struct mm_struct *mm, 759 struct vm_area_struct *prev, unsigned long addr, 760 unsigned long end, unsigned long vm_flags, 761 struct anon_vma *anon_vma, struct file *file, 762 pgoff_t pgoff, struct mempolicy *policy) 763{ 764 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 765 struct vm_area_struct *area, *next; 766 767 /* 768 * We later require that vma->vm_flags == vm_flags, 769 * so this tests vma->vm_flags & VM_SPECIAL, too. 770 */ 771 if (vm_flags & VM_SPECIAL) 772 return NULL; 773 774 if (prev) 775 next = prev->vm_next; 776 else 777 next = mm->mmap; 778 area = next; 779 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 780 next = next->vm_next; 781 782 /* 783 * Can it merge with the predecessor? 784 */ 785 if (prev && prev->vm_end == addr && 786 mpol_equal(vma_policy(prev), policy) && 787 can_vma_merge_after(prev, vm_flags, 788 anon_vma, file, pgoff)) { 789 /* 790 * OK, it can. Can we now merge in the successor as well? 791 */ 792 if (next && end == next->vm_start && 793 mpol_equal(policy, vma_policy(next)) && 794 can_vma_merge_before(next, vm_flags, 795 anon_vma, file, pgoff+pglen) && 796 is_mergeable_anon_vma(prev->anon_vma, 797 next->anon_vma)) { 798 /* cases 1, 6 */ 799 vma_adjust(prev, prev->vm_start, 800 next->vm_end, prev->vm_pgoff, NULL); 801 } else /* cases 2, 5, 7 */ 802 vma_adjust(prev, prev->vm_start, 803 end, prev->vm_pgoff, NULL); 804 return prev; 805 } 806 807 /* 808 * Can this new request be merged in front of next? 809 */ 810 if (next && end == next->vm_start && 811 mpol_equal(policy, vma_policy(next)) && 812 can_vma_merge_before(next, vm_flags, 813 anon_vma, file, pgoff+pglen)) { 814 if (prev && addr < prev->vm_end) /* case 4 */ 815 vma_adjust(prev, prev->vm_start, 816 addr, prev->vm_pgoff, NULL); 817 else /* cases 3, 8 */ 818 vma_adjust(area, addr, next->vm_end, 819 next->vm_pgoff - pglen, NULL); 820 return area; 821 } 822 823 return NULL; 824} 825 826/* 827 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 828 * neighbouring vmas for a suitable anon_vma, before it goes off 829 * to allocate a new anon_vma. It checks because a repetitive 830 * sequence of mprotects and faults may otherwise lead to distinct 831 * anon_vmas being allocated, preventing vma merge in subsequent 832 * mprotect. 833 */ 834struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 835{ 836 struct vm_area_struct *near; 837 unsigned long vm_flags; 838 839 near = vma->vm_next; 840 if (!near) 841 goto try_prev; 842 843 /* 844 * Since only mprotect tries to remerge vmas, match flags 845 * which might be mprotected into each other later on. 846 * Neither mlock nor madvise tries to remerge at present, 847 * so leave their flags as obstructing a merge. 848 */ 849 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 850 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 851 852 if (near->anon_vma && vma->vm_end == near->vm_start && 853 mpol_equal(vma_policy(vma), vma_policy(near)) && 854 can_vma_merge_before(near, vm_flags, 855 NULL, vma->vm_file, vma->vm_pgoff + 856 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 857 return near->anon_vma; 858try_prev: 859 /* 860 * It is potentially slow to have to call find_vma_prev here. 861 * But it's only on the first write fault on the vma, not 862 * every time, and we could devise a way to avoid it later 863 * (e.g. stash info in next's anon_vma_node when assigning 864 * an anon_vma, or when trying vma_merge). Another time. 865 */ 866 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 867 if (!near) 868 goto none; 869 870 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 871 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 872 873 if (near->anon_vma && near->vm_end == vma->vm_start && 874 mpol_equal(vma_policy(near), vma_policy(vma)) && 875 can_vma_merge_after(near, vm_flags, 876 NULL, vma->vm_file, vma->vm_pgoff)) 877 return near->anon_vma; 878none: 879 /* 880 * There's no absolute need to look only at touching neighbours: 881 * we could search further afield for "compatible" anon_vmas. 882 * But it would probably just be a waste of time searching, 883 * or lead to too many vmas hanging off the same anon_vma. 884 * We're trying to allow mprotect remerging later on, 885 * not trying to minimize memory used for anon_vmas. 886 */ 887 return NULL; 888} 889 890#ifdef CONFIG_PROC_FS 891void vm_stat_account(struct mm_struct *mm, unsigned long flags, 892 struct file *file, long pages) 893{ 894 const unsigned long stack_flags 895 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 896 897 if (file) { 898 mm->shared_vm += pages; 899 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 900 mm->exec_vm += pages; 901 } else if (flags & stack_flags) 902 mm->stack_vm += pages; 903 if (flags & (VM_RESERVED|VM_IO)) 904 mm->reserved_vm += pages; 905} 906#endif /* CONFIG_PROC_FS */ 907 908/* 909 * The caller must hold down_write(current->mm->mmap_sem). 910 */ 911 912unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 913 unsigned long len, unsigned long prot, 914 unsigned long flags, unsigned long pgoff) 915{ 916 struct mm_struct * mm = current->mm; 917 struct inode *inode; 918 unsigned int vm_flags; 919 int error; 920 int accountable = 1; 921 unsigned long reqprot = prot; 922 923 /* 924 * Does the application expect PROT_READ to imply PROT_EXEC? 925 * 926 * (the exception is when the underlying filesystem is noexec 927 * mounted, in which case we dont add PROT_EXEC.) 928 */ 929 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 930 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 931 prot |= PROT_EXEC; 932 933 if (!len) 934 return -EINVAL; 935 936 if (!(flags & MAP_FIXED)) 937 addr = round_hint_to_min(addr); 938 939 error = arch_mmap_check(addr, len, flags); 940 if (error) 941 return error; 942 943 /* Careful about overflows.. */ 944 len = PAGE_ALIGN(len); 945 if (!len || len > TASK_SIZE) 946 return -ENOMEM; 947 948 /* offset overflow? */ 949 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 950 return -EOVERFLOW; 951 952 /* Too many mappings? */ 953 if (mm->map_count > sysctl_max_map_count) 954 return -ENOMEM; 955 956 /* Obtain the address to map to. we verify (or select) it and ensure 957 * that it represents a valid section of the address space. 958 */ 959 addr = get_unmapped_area(file, addr, len, pgoff, flags); 960 if (addr & ~PAGE_MASK) 961 return addr; 962 963 /* Do simple checking here so the lower-level routines won't have 964 * to. we assume access permissions have been handled by the open 965 * of the memory object, so we don't do any here. 966 */ 967 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 968 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 969 970 if (flags & MAP_LOCKED) { 971 if (!can_do_mlock()) 972 return -EPERM; 973 vm_flags |= VM_LOCKED; 974 } 975 /* mlock MCL_FUTURE? */ 976 if (vm_flags & VM_LOCKED) { 977 unsigned long locked, lock_limit; 978 locked = len >> PAGE_SHIFT; 979 locked += mm->locked_vm; 980 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 981 lock_limit >>= PAGE_SHIFT; 982 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 983 return -EAGAIN; 984 } 985 986 inode = file ? file->f_path.dentry->d_inode : NULL; 987 988 if (file) { 989 switch (flags & MAP_TYPE) { 990 case MAP_SHARED: 991 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 992 return -EACCES; 993 994 /* 995 * Make sure we don't allow writing to an append-only 996 * file.. 997 */ 998 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 999 return -EACCES; 1000 1001 /* 1002 * Make sure there are no mandatory locks on the file. 1003 */ 1004 if (locks_verify_locked(inode)) 1005 return -EAGAIN; 1006 1007 vm_flags |= VM_SHARED | VM_MAYSHARE; 1008 if (!(file->f_mode & FMODE_WRITE)) 1009 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1010 1011 /* fall through */ 1012 case MAP_PRIVATE: 1013 if (!(file->f_mode & FMODE_READ)) 1014 return -EACCES; 1015 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1016 if (vm_flags & VM_EXEC) 1017 return -EPERM; 1018 vm_flags &= ~VM_MAYEXEC; 1019 } 1020 if (is_file_hugepages(file)) 1021 accountable = 0; 1022 1023 if (!file->f_op || !file->f_op->mmap) 1024 return -ENODEV; 1025 break; 1026 1027 default: 1028 return -EINVAL; 1029 } 1030 } else { 1031 switch (flags & MAP_TYPE) { 1032 case MAP_SHARED: 1033 vm_flags |= VM_SHARED | VM_MAYSHARE; 1034 break; 1035 case MAP_PRIVATE: 1036 /* 1037 * Set pgoff according to addr for anon_vma. 1038 */ 1039 pgoff = addr >> PAGE_SHIFT; 1040 break; 1041 default: 1042 return -EINVAL; 1043 } 1044 } 1045 1046 error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1047 if (error) 1048 return error; 1049 1050 return mmap_region(file, addr, len, flags, vm_flags, pgoff, 1051 accountable); 1052} 1053EXPORT_SYMBOL(do_mmap_pgoff); 1054 1055/* 1056 * Some shared mappigns will want the pages marked read-only 1057 * to track write events. If so, we'll downgrade vm_page_prot 1058 * to the private version (using protection_map[] without the 1059 * VM_SHARED bit). 1060 */ 1061int vma_wants_writenotify(struct vm_area_struct *vma) 1062{ 1063 unsigned int vm_flags = vma->vm_flags; 1064 1065 /* If it was private or non-writable, the write bit is already clear */ 1066 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1067 return 0; 1068 1069 /* The backer wishes to know when pages are first written to? */ 1070 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1071 return 1; 1072 1073 /* The open routine did something to the protections already? */ 1074 if (pgprot_val(vma->vm_page_prot) != 1075 pgprot_val(vm_get_page_prot(vm_flags))) 1076 return 0; 1077 1078 /* Specialty mapping? */ 1079 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) 1080 return 0; 1081 1082 /* Can the mapping track the dirty pages? */ 1083 return vma->vm_file && vma->vm_file->f_mapping && 1084 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1085} 1086 1087unsigned long mmap_region(struct file *file, unsigned long addr, 1088 unsigned long len, unsigned long flags, 1089 unsigned int vm_flags, unsigned long pgoff, 1090 int accountable) 1091{ 1092 struct mm_struct *mm = current->mm; 1093 struct vm_area_struct *vma, *prev; 1094 int correct_wcount = 0; 1095 int error; 1096 struct rb_node **rb_link, *rb_parent; 1097 unsigned long charged = 0; 1098 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; 1099 1100 /* Clear old maps */ 1101 error = -ENOMEM; 1102munmap_back: 1103 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1104 if (vma && vma->vm_start < addr + len) { 1105 if (do_munmap(mm, addr, len)) 1106 return -ENOMEM; 1107 goto munmap_back; 1108 } 1109 1110 /* Check against address space limit. */ 1111 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1112 return -ENOMEM; 1113 1114 if (flags & MAP_NORESERVE) 1115 vm_flags |= VM_NORESERVE; 1116 1117 if (accountable && (!(flags & MAP_NORESERVE) || 1118 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { 1119 if (vm_flags & VM_SHARED) { 1120 /* Check memory availability in shmem_file_setup? */ 1121 vm_flags |= VM_ACCOUNT; 1122 } else if (vm_flags & VM_WRITE) { 1123 /* 1124 * Private writable mapping: check memory availability 1125 */ 1126 charged = len >> PAGE_SHIFT; 1127 if (security_vm_enough_memory(charged)) 1128 return -ENOMEM; 1129 vm_flags |= VM_ACCOUNT; 1130 } 1131 } 1132 1133 /* 1134 * Can we just expand an old private anonymous mapping? 1135 * The VM_SHARED test is necessary because shmem_zero_setup 1136 * will create the file object for a shared anonymous map below. 1137 */ 1138 if (!file && !(vm_flags & VM_SHARED) && 1139 vma_merge(mm, prev, addr, addr + len, vm_flags, 1140 NULL, NULL, pgoff, NULL)) 1141 goto out; 1142 1143 /* 1144 * Determine the object being mapped and call the appropriate 1145 * specific mapper. the address has already been validated, but 1146 * not unmapped, but the maps are removed from the list. 1147 */ 1148 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1149 if (!vma) { 1150 error = -ENOMEM; 1151 goto unacct_error; 1152 } 1153 1154 vma->vm_mm = mm; 1155 vma->vm_start = addr; 1156 vma->vm_end = addr + len; 1157 vma->vm_flags = vm_flags; 1158 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1159 vma->vm_pgoff = pgoff; 1160 1161 if (file) { 1162 error = -EINVAL; 1163 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1164 goto free_vma; 1165 if (vm_flags & VM_DENYWRITE) { 1166 error = deny_write_access(file); 1167 if (error) 1168 goto free_vma; 1169 correct_wcount = 1; 1170 } 1171 vma->vm_file = file; 1172 get_file(file); 1173 error = file->f_op->mmap(file, vma); 1174 if (error) 1175 goto unmap_and_free_vma; 1176 if (vm_flags & VM_EXECUTABLE) 1177 added_exe_file_vma(mm); 1178 } else if (vm_flags & VM_SHARED) { 1179 error = shmem_zero_setup(vma); 1180 if (error) 1181 goto free_vma; 1182 } 1183 1184 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1185 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1186 * that memory reservation must be checked; but that reservation 1187 * belongs to shared memory object, not to vma: so now clear it. 1188 */ 1189 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1190 vma->vm_flags &= ~VM_ACCOUNT; 1191 1192 /* Can addr have changed?? 1193 * 1194 * Answer: Yes, several device drivers can do it in their 1195 * f_op->mmap method. -DaveM 1196 */ 1197 addr = vma->vm_start; 1198 pgoff = vma->vm_pgoff; 1199 vm_flags = vma->vm_flags; 1200 1201 if (vma_wants_writenotify(vma)) 1202 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); 1203 1204 if (file && vma_merge(mm, prev, addr, vma->vm_end, 1205 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1206 mpol_put(vma_policy(vma)); 1207 kmem_cache_free(vm_area_cachep, vma); 1208 fput(file); 1209 if (vm_flags & VM_EXECUTABLE) 1210 removed_exe_file_vma(mm); 1211 } else { 1212 vma_link(mm, vma, prev, rb_link, rb_parent); 1213 file = vma->vm_file; 1214 } 1215 1216 /* Once vma denies write, undo our temporary denial count */ 1217 if (correct_wcount) 1218 atomic_inc(&inode->i_writecount); 1219out: 1220 mm->total_vm += len >> PAGE_SHIFT; 1221 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1222 if (vm_flags & VM_LOCKED) { 1223 mm->locked_vm += len >> PAGE_SHIFT; 1224 make_pages_present(addr, addr + len); 1225 } 1226 if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) 1227 make_pages_present(addr, addr + len); 1228 return addr; 1229 1230unmap_and_free_vma: 1231 if (correct_wcount) 1232 atomic_inc(&inode->i_writecount); 1233 vma->vm_file = NULL; 1234 fput(file); 1235 1236 /* Undo any partial mapping done by a device driver. */ 1237 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1238 charged = 0; 1239free_vma: 1240 kmem_cache_free(vm_area_cachep, vma); 1241unacct_error: 1242 if (charged) 1243 vm_unacct_memory(charged); 1244 return error; 1245} 1246 1247/* Get an address range which is currently unmapped. 1248 * For shmat() with addr=0. 1249 * 1250 * Ugly calling convention alert: 1251 * Return value with the low bits set means error value, 1252 * ie 1253 * if (ret & ~PAGE_MASK) 1254 * error = ret; 1255 * 1256 * This function "knows" that -ENOMEM has the bits set. 1257 */ 1258#ifndef HAVE_ARCH_UNMAPPED_AREA 1259unsigned long 1260arch_get_unmapped_area(struct file *filp, unsigned long addr, 1261 unsigned long len, unsigned long pgoff, unsigned long flags) 1262{ 1263 struct mm_struct *mm = current->mm; 1264 struct vm_area_struct *vma; 1265 unsigned long start_addr; 1266 1267 if (len > TASK_SIZE) 1268 return -ENOMEM; 1269 1270 if (flags & MAP_FIXED) 1271 return addr; 1272 1273 if (addr) { 1274 addr = PAGE_ALIGN(addr); 1275 vma = find_vma(mm, addr); 1276 if (TASK_SIZE - len >= addr && 1277 (!vma || addr + len <= vma->vm_start)) 1278 return addr; 1279 } 1280 if (len > mm->cached_hole_size) { 1281 start_addr = addr = mm->free_area_cache; 1282 } else { 1283 start_addr = addr = TASK_UNMAPPED_BASE; 1284 mm->cached_hole_size = 0; 1285 } 1286 1287full_search: 1288 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1289 /* At this point: (!vma || addr < vma->vm_end). */ 1290 if (TASK_SIZE - len < addr) { 1291 /* 1292 * Start a new search - just in case we missed 1293 * some holes. 1294 */ 1295 if (start_addr != TASK_UNMAPPED_BASE) { 1296 addr = TASK_UNMAPPED_BASE; 1297 start_addr = addr; 1298 mm->cached_hole_size = 0; 1299 goto full_search; 1300 } 1301 return -ENOMEM; 1302 } 1303 if (!vma || addr + len <= vma->vm_start) { 1304 /* 1305 * Remember the place where we stopped the search: 1306 */ 1307 mm->free_area_cache = addr + len; 1308 return addr; 1309 } 1310 if (addr + mm->cached_hole_size < vma->vm_start) 1311 mm->cached_hole_size = vma->vm_start - addr; 1312 addr = vma->vm_end; 1313 } 1314} 1315#endif 1316 1317void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1318{ 1319 /* 1320 * Is this a new hole at the lowest possible address? 1321 */ 1322 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1323 mm->free_area_cache = addr; 1324 mm->cached_hole_size = ~0UL; 1325 } 1326} 1327 1328/* 1329 * This mmap-allocator allocates new areas top-down from below the 1330 * stack's low limit (the base): 1331 */ 1332#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1333unsigned long 1334arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1335 const unsigned long len, const unsigned long pgoff, 1336 const unsigned long flags) 1337{ 1338 struct vm_area_struct *vma; 1339 struct mm_struct *mm = current->mm; 1340 unsigned long addr = addr0; 1341 1342 /* requested length too big for entire address space */ 1343 if (len > TASK_SIZE) 1344 return -ENOMEM; 1345 1346 if (flags & MAP_FIXED) 1347 return addr; 1348 1349 /* requesting a specific address */ 1350 if (addr) { 1351 addr = PAGE_ALIGN(addr); 1352 vma = find_vma(mm, addr); 1353 if (TASK_SIZE - len >= addr && 1354 (!vma || addr + len <= vma->vm_start)) 1355 return addr; 1356 } 1357 1358 /* check if free_area_cache is useful for us */ 1359 if (len <= mm->cached_hole_size) { 1360 mm->cached_hole_size = 0; 1361 mm->free_area_cache = mm->mmap_base; 1362 } 1363 1364 /* either no address requested or can't fit in requested address hole */ 1365 addr = mm->free_area_cache; 1366 1367 /* make sure it can fit in the remaining address space */ 1368 if (addr > len) { 1369 vma = find_vma(mm, addr-len); 1370 if (!vma || addr <= vma->vm_start) 1371 /* remember the address as a hint for next time */ 1372 return (mm->free_area_cache = addr-len); 1373 } 1374 1375 if (mm->mmap_base < len) 1376 goto bottomup; 1377 1378 addr = mm->mmap_base-len; 1379 1380 do { 1381 /* 1382 * Lookup failure means no vma is above this address, 1383 * else if new region fits below vma->vm_start, 1384 * return with success: 1385 */ 1386 vma = find_vma(mm, addr); 1387 if (!vma || addr+len <= vma->vm_start) 1388 /* remember the address as a hint for next time */ 1389 return (mm->free_area_cache = addr); 1390 1391 /* remember the largest hole we saw so far */ 1392 if (addr + mm->cached_hole_size < vma->vm_start) 1393 mm->cached_hole_size = vma->vm_start - addr; 1394 1395 /* try just below the current vma->vm_start */ 1396 addr = vma->vm_start-len; 1397 } while (len < vma->vm_start); 1398 1399bottomup: 1400 /* 1401 * A failed mmap() very likely causes application failure, 1402 * so fall back to the bottom-up function here. This scenario 1403 * can happen with large stack limits and large mmap() 1404 * allocations. 1405 */ 1406 mm->cached_hole_size = ~0UL; 1407 mm->free_area_cache = TASK_UNMAPPED_BASE; 1408 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1409 /* 1410 * Restore the topdown base: 1411 */ 1412 mm->free_area_cache = mm->mmap_base; 1413 mm->cached_hole_size = ~0UL; 1414 1415 return addr; 1416} 1417#endif 1418 1419void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1420{ 1421 /* 1422 * Is this a new hole at the highest possible address? 1423 */ 1424 if (addr > mm->free_area_cache) 1425 mm->free_area_cache = addr; 1426 1427 /* dont allow allocations above current base */ 1428 if (mm->free_area_cache > mm->mmap_base) 1429 mm->free_area_cache = mm->mmap_base; 1430} 1431 1432unsigned long 1433get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1434 unsigned long pgoff, unsigned long flags) 1435{ 1436 unsigned long (*get_area)(struct file *, unsigned long, 1437 unsigned long, unsigned long, unsigned long); 1438 1439 get_area = current->mm->get_unmapped_area; 1440 if (file && file->f_op && file->f_op->get_unmapped_area) 1441 get_area = file->f_op->get_unmapped_area; 1442 addr = get_area(file, addr, len, pgoff, flags); 1443 if (IS_ERR_VALUE(addr)) 1444 return addr; 1445 1446 if (addr > TASK_SIZE - len) 1447 return -ENOMEM; 1448 if (addr & ~PAGE_MASK) 1449 return -EINVAL; 1450 1451 return arch_rebalance_pgtables(addr, len); 1452} 1453 1454EXPORT_SYMBOL(get_unmapped_area); 1455 1456/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1457struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1458{ 1459 struct vm_area_struct *vma = NULL; 1460 1461 if (mm) { 1462 /* Check the cache first. */ 1463 /* (Cache hit rate is typically around 35%.) */ 1464 vma = mm->mmap_cache; 1465 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1466 struct rb_node * rb_node; 1467 1468 rb_node = mm->mm_rb.rb_node; 1469 vma = NULL; 1470 1471 while (rb_node) { 1472 struct vm_area_struct * vma_tmp; 1473 1474 vma_tmp = rb_entry(rb_node, 1475 struct vm_area_struct, vm_rb); 1476 1477 if (vma_tmp->vm_end > addr) { 1478 vma = vma_tmp; 1479 if (vma_tmp->vm_start <= addr) 1480 break; 1481 rb_node = rb_node->rb_left; 1482 } else 1483 rb_node = rb_node->rb_right; 1484 } 1485 if (vma) 1486 mm->mmap_cache = vma; 1487 } 1488 } 1489 return vma; 1490} 1491 1492EXPORT_SYMBOL(find_vma); 1493 1494/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1495struct vm_area_struct * 1496find_vma_prev(struct mm_struct *mm, unsigned long addr, 1497 struct vm_area_struct **pprev) 1498{ 1499 struct vm_area_struct *vma = NULL, *prev = NULL; 1500 struct rb_node * rb_node; 1501 if (!mm) 1502 goto out; 1503 1504 /* Guard against addr being lower than the first VMA */ 1505 vma = mm->mmap; 1506 1507 /* Go through the RB tree quickly. */ 1508 rb_node = mm->mm_rb.rb_node; 1509 1510 while (rb_node) { 1511 struct vm_area_struct *vma_tmp; 1512 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1513 1514 if (addr < vma_tmp->vm_end) { 1515 rb_node = rb_node->rb_left; 1516 } else { 1517 prev = vma_tmp; 1518 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1519 break; 1520 rb_node = rb_node->rb_right; 1521 } 1522 } 1523 1524out: 1525 *pprev = prev; 1526 return prev ? prev->vm_next : vma; 1527} 1528 1529/* 1530 * Verify that the stack growth is acceptable and 1531 * update accounting. This is shared with both the 1532 * grow-up and grow-down cases. 1533 */ 1534static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1535{ 1536 struct mm_struct *mm = vma->vm_mm; 1537 struct rlimit *rlim = current->signal->rlim; 1538 unsigned long new_start; 1539 1540 /* address space limit tests */ 1541 if (!may_expand_vm(mm, grow)) 1542 return -ENOMEM; 1543 1544 /* Stack limit test */ 1545 if (size > rlim[RLIMIT_STACK].rlim_cur) 1546 return -ENOMEM; 1547 1548 /* mlock limit tests */ 1549 if (vma->vm_flags & VM_LOCKED) { 1550 unsigned long locked; 1551 unsigned long limit; 1552 locked = mm->locked_vm + grow; 1553 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1554 if (locked > limit && !capable(CAP_IPC_LOCK)) 1555 return -ENOMEM; 1556 } 1557 1558 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1559 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1560 vma->vm_end - size; 1561 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1562 return -EFAULT; 1563 1564 /* 1565 * Overcommit.. This must be the final test, as it will 1566 * update security statistics. 1567 */ 1568 if (security_vm_enough_memory(grow)) 1569 return -ENOMEM; 1570 1571 /* Ok, everything looks good - let it rip */ 1572 mm->total_vm += grow; 1573 if (vma->vm_flags & VM_LOCKED) 1574 mm->locked_vm += grow; 1575 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1576 return 0; 1577} 1578 1579#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1580/* 1581 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1582 * vma is the last one with address > vma->vm_end. Have to extend vma. 1583 */ 1584#ifndef CONFIG_IA64 1585static inline 1586#endif 1587int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1588{ 1589 int error; 1590 1591 if (!(vma->vm_flags & VM_GROWSUP)) 1592 return -EFAULT; 1593 1594 /* 1595 * We must make sure the anon_vma is allocated 1596 * so that the anon_vma locking is not a noop. 1597 */ 1598 if (unlikely(anon_vma_prepare(vma))) 1599 return -ENOMEM; 1600 anon_vma_lock(vma); 1601 1602 /* 1603 * vma->vm_start/vm_end cannot change under us because the caller 1604 * is required to hold the mmap_sem in read mode. We need the 1605 * anon_vma lock to serialize against concurrent expand_stacks. 1606 * Also guard against wrapping around to address 0. 1607 */ 1608 if (address < PAGE_ALIGN(address+4)) 1609 address = PAGE_ALIGN(address+4); 1610 else { 1611 anon_vma_unlock(vma); 1612 return -ENOMEM; 1613 } 1614 error = 0; 1615 1616 /* Somebody else might have raced and expanded it already */ 1617 if (address > vma->vm_end) { 1618 unsigned long size, grow; 1619 1620 size = address - vma->vm_start; 1621 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1622 1623 error = acct_stack_growth(vma, size, grow); 1624 if (!error) 1625 vma->vm_end = address; 1626 } 1627 anon_vma_unlock(vma); 1628 return error; 1629} 1630#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1631 1632/* 1633 * vma is the first one with address < vma->vm_start. Have to extend vma. 1634 */ 1635static inline int expand_downwards(struct vm_area_struct *vma, 1636 unsigned long address) 1637{ 1638 int error; 1639 1640 /* 1641 * We must make sure the anon_vma is allocated 1642 * so that the anon_vma locking is not a noop. 1643 */ 1644 if (unlikely(anon_vma_prepare(vma))) 1645 return -ENOMEM; 1646 1647 address &= PAGE_MASK; 1648 error = security_file_mmap(NULL, 0, 0, 0, address, 1); 1649 if (error) 1650 return error; 1651 1652 anon_vma_lock(vma); 1653 1654 /* 1655 * vma->vm_start/vm_end cannot change under us because the caller 1656 * is required to hold the mmap_sem in read mode. We need the 1657 * anon_vma lock to serialize against concurrent expand_stacks. 1658 */ 1659 1660 /* Somebody else might have raced and expanded it already */ 1661 if (address < vma->vm_start) { 1662 unsigned long size, grow; 1663 1664 size = vma->vm_end - address; 1665 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1666 1667 error = acct_stack_growth(vma, size, grow); 1668 if (!error) { 1669 vma->vm_start = address; 1670 vma->vm_pgoff -= grow; 1671 } 1672 } 1673 anon_vma_unlock(vma); 1674 return error; 1675} 1676 1677int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) 1678{ 1679 return expand_downwards(vma, address); 1680} 1681 1682#ifdef CONFIG_STACK_GROWSUP 1683int expand_stack(struct vm_area_struct *vma, unsigned long address) 1684{ 1685 return expand_upwards(vma, address); 1686} 1687 1688struct vm_area_struct * 1689find_extend_vma(struct mm_struct *mm, unsigned long addr) 1690{ 1691 struct vm_area_struct *vma, *prev; 1692 1693 addr &= PAGE_MASK; 1694 vma = find_vma_prev(mm, addr, &prev); 1695 if (vma && (vma->vm_start <= addr)) 1696 return vma; 1697 if (!prev || expand_stack(prev, addr)) 1698 return NULL; 1699 if (prev->vm_flags & VM_LOCKED) 1700 make_pages_present(addr, prev->vm_end); 1701 return prev; 1702} 1703#else 1704int expand_stack(struct vm_area_struct *vma, unsigned long address) 1705{ 1706 return expand_downwards(vma, address); 1707} 1708 1709struct vm_area_struct * 1710find_extend_vma(struct mm_struct * mm, unsigned long addr) 1711{ 1712 struct vm_area_struct * vma; 1713 unsigned long start; 1714 1715 addr &= PAGE_MASK; 1716 vma = find_vma(mm,addr); 1717 if (!vma) 1718 return NULL; 1719 if (vma->vm_start <= addr) 1720 return vma; 1721 if (!(vma->vm_flags & VM_GROWSDOWN)) 1722 return NULL; 1723 start = vma->vm_start; 1724 if (expand_stack(vma, addr)) 1725 return NULL; 1726 if (vma->vm_flags & VM_LOCKED) 1727 make_pages_present(addr, start); 1728 return vma; 1729} 1730#endif 1731 1732/* 1733 * Ok - we have the memory areas we should free on the vma list, 1734 * so release them, and do the vma updates. 1735 * 1736 * Called with the mm semaphore held. 1737 */ 1738static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1739{ 1740 /* Update high watermark before we lower total_vm */ 1741 update_hiwater_vm(mm); 1742 do { 1743 long nrpages = vma_pages(vma); 1744 1745 mm->total_vm -= nrpages; 1746 if (vma->vm_flags & VM_LOCKED) 1747 mm->locked_vm -= nrpages; 1748 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1749 vma = remove_vma(vma); 1750 } while (vma); 1751 validate_mm(mm); 1752} 1753 1754/* 1755 * Get rid of page table information in the indicated region. 1756 * 1757 * Called with the mm semaphore held. 1758 */ 1759static void unmap_region(struct mm_struct *mm, 1760 struct vm_area_struct *vma, struct vm_area_struct *prev, 1761 unsigned long start, unsigned long end) 1762{ 1763 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1764 struct mmu_gather *tlb; 1765 unsigned long nr_accounted = 0; 1766 1767 lru_add_drain(); 1768 tlb = tlb_gather_mmu(mm, 0); 1769 update_hiwater_rss(mm); 1770 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1771 vm_unacct_memory(nr_accounted); 1772 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1773 next? next->vm_start: 0); 1774 tlb_finish_mmu(tlb, start, end); 1775} 1776 1777/* 1778 * Create a list of vma's touched by the unmap, removing them from the mm's 1779 * vma list as we go.. 1780 */ 1781static void 1782detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1783 struct vm_area_struct *prev, unsigned long end) 1784{ 1785 struct vm_area_struct **insertion_point; 1786 struct vm_area_struct *tail_vma = NULL; 1787 unsigned long addr; 1788 1789 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1790 do { 1791 rb_erase(&vma->vm_rb, &mm->mm_rb); 1792 mm->map_count--; 1793 tail_vma = vma; 1794 vma = vma->vm_next; 1795 } while (vma && vma->vm_start < end); 1796 *insertion_point = vma; 1797 tail_vma->vm_next = NULL; 1798 if (mm->unmap_area == arch_unmap_area) 1799 addr = prev ? prev->vm_end : mm->mmap_base; 1800 else 1801 addr = vma ? vma->vm_start : mm->mmap_base; 1802 mm->unmap_area(mm, addr); 1803 mm->mmap_cache = NULL; /* Kill the cache. */ 1804} 1805 1806/* 1807 * Split a vma into two pieces at address 'addr', a new vma is allocated 1808 * either for the first part or the tail. 1809 */ 1810int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1811 unsigned long addr, int new_below) 1812{ 1813 struct mempolicy *pol; 1814 struct vm_area_struct *new; 1815 1816 if (is_vm_hugetlb_page(vma) && (addr & 1817 ~(huge_page_mask(hstate_vma(vma))))) 1818 return -EINVAL; 1819 1820 if (mm->map_count >= sysctl_max_map_count) 1821 return -ENOMEM; 1822 1823 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1824 if (!new) 1825 return -ENOMEM; 1826 1827 /* most fields are the same, copy all, and then fixup */ 1828 *new = *vma; 1829 1830 if (new_below) 1831 new->vm_end = addr; 1832 else { 1833 new->vm_start = addr; 1834 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1835 } 1836 1837 pol = mpol_dup(vma_policy(vma)); 1838 if (IS_ERR(pol)) { 1839 kmem_cache_free(vm_area_cachep, new); 1840 return PTR_ERR(pol); 1841 } 1842 vma_set_policy(new, pol); 1843 1844 if (new->vm_file) { 1845 get_file(new->vm_file); 1846 if (vma->vm_flags & VM_EXECUTABLE) 1847 added_exe_file_vma(mm); 1848 } 1849 1850 if (new->vm_ops && new->vm_ops->open) 1851 new->vm_ops->open(new); 1852 1853 if (new_below) 1854 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1855 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1856 else 1857 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1858 1859 return 0; 1860} 1861 1862/* Munmap is split into 2 main parts -- this part which finds 1863 * what needs doing, and the areas themselves, which do the 1864 * work. This now handles partial unmappings. 1865 * Jeremy Fitzhardinge <jeremy@goop.org> 1866 */ 1867int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1868{ 1869 unsigned long end; 1870 struct vm_area_struct *vma, *prev, *last; 1871 1872 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1873 return -EINVAL; 1874 1875 if ((len = PAGE_ALIGN(len)) == 0) 1876 return -EINVAL; 1877 1878 /* Find the first overlapping VMA */ 1879 vma = find_vma_prev(mm, start, &prev); 1880 if (!vma) 1881 return 0; 1882 /* we have start < vma->vm_end */ 1883 1884 /* if it doesn't overlap, we have nothing.. */ 1885 end = start + len; 1886 if (vma->vm_start >= end) 1887 return 0; 1888 1889 /* 1890 * If we need to split any vma, do it now to save pain later. 1891 * 1892 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1893 * unmapped vm_area_struct will remain in use: so lower split_vma 1894 * places tmp vma above, and higher split_vma places tmp vma below. 1895 */ 1896 if (start > vma->vm_start) { 1897 int error = split_vma(mm, vma, start, 0); 1898 if (error) 1899 return error; 1900 prev = vma; 1901 } 1902 1903 /* Does it split the last one? */ 1904 last = find_vma(mm, end); 1905 if (last && end > last->vm_start) { 1906 int error = split_vma(mm, last, end, 1); 1907 if (error) 1908 return error; 1909 } 1910 vma = prev? prev->vm_next: mm->mmap; 1911 1912 /* 1913 * Remove the vma's, and unmap the actual pages 1914 */ 1915 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1916 unmap_region(mm, vma, prev, start, end); 1917 1918 /* Fix up all other VM information */ 1919 remove_vma_list(mm, vma); 1920 1921 return 0; 1922} 1923 1924EXPORT_SYMBOL(do_munmap); 1925 1926asmlinkage long sys_munmap(unsigned long addr, size_t len) 1927{ 1928 int ret; 1929 struct mm_struct *mm = current->mm; 1930 1931 profile_munmap(addr); 1932 1933 down_write(&mm->mmap_sem); 1934 ret = do_munmap(mm, addr, len); 1935 up_write(&mm->mmap_sem); 1936 return ret; 1937} 1938 1939static inline void verify_mm_writelocked(struct mm_struct *mm) 1940{ 1941#ifdef CONFIG_DEBUG_VM 1942 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1943 WARN_ON(1); 1944 up_read(&mm->mmap_sem); 1945 } 1946#endif 1947} 1948 1949/* 1950 * this is really a simplified "do_mmap". it only handles 1951 * anonymous maps. eventually we may be able to do some 1952 * brk-specific accounting here. 1953 */ 1954unsigned long do_brk(unsigned long addr, unsigned long len) 1955{ 1956 struct mm_struct * mm = current->mm; 1957 struct vm_area_struct * vma, * prev; 1958 unsigned long flags; 1959 struct rb_node ** rb_link, * rb_parent; 1960 pgoff_t pgoff = addr >> PAGE_SHIFT; 1961 int error; 1962 1963 len = PAGE_ALIGN(len); 1964 if (!len) 1965 return addr; 1966 1967 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1968 return -EINVAL; 1969 1970 if (is_hugepage_only_range(mm, addr, len)) 1971 return -EINVAL; 1972 1973 error = security_file_mmap(NULL, 0, 0, 0, addr, 1); 1974 if (error) 1975 return error; 1976 1977 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1978 1979 error = arch_mmap_check(addr, len, flags); 1980 if (error) 1981 return error; 1982 1983 /* 1984 * mlock MCL_FUTURE? 1985 */ 1986 if (mm->def_flags & VM_LOCKED) { 1987 unsigned long locked, lock_limit; 1988 locked = len >> PAGE_SHIFT; 1989 locked += mm->locked_vm; 1990 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1991 lock_limit >>= PAGE_SHIFT; 1992 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1993 return -EAGAIN; 1994 } 1995 1996 /* 1997 * mm->mmap_sem is required to protect against another thread 1998 * changing the mappings in case we sleep. 1999 */ 2000 verify_mm_writelocked(mm); 2001 2002 /* 2003 * Clear old maps. this also does some error checking for us 2004 */ 2005 munmap_back: 2006 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2007 if (vma && vma->vm_start < addr + len) { 2008 if (do_munmap(mm, addr, len)) 2009 return -ENOMEM; 2010 goto munmap_back; 2011 } 2012 2013 /* Check against address space limits *after* clearing old maps... */ 2014 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 2015 return -ENOMEM; 2016 2017 if (mm->map_count > sysctl_max_map_count) 2018 return -ENOMEM; 2019 2020 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 2021 return -ENOMEM; 2022 2023 /* Can we just expand an old private anonymous mapping? */ 2024 if (vma_merge(mm, prev, addr, addr + len, flags, 2025 NULL, NULL, pgoff, NULL)) 2026 goto out; 2027 2028 /* 2029 * create a vma struct for an anonymous mapping 2030 */ 2031 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2032 if (!vma) { 2033 vm_unacct_memory(len >> PAGE_SHIFT); 2034 return -ENOMEM; 2035 } 2036 2037 vma->vm_mm = mm; 2038 vma->vm_start = addr; 2039 vma->vm_end = addr + len; 2040 vma->vm_pgoff = pgoff; 2041 vma->vm_flags = flags; 2042 vma->vm_page_prot = vm_get_page_prot(flags); 2043 vma_link(mm, vma, prev, rb_link, rb_parent); 2044out: 2045 mm->total_vm += len >> PAGE_SHIFT; 2046 if (flags & VM_LOCKED) { 2047 mm->locked_vm += len >> PAGE_SHIFT; 2048 make_pages_present(addr, addr + len); 2049 } 2050 return addr; 2051} 2052 2053EXPORT_SYMBOL(do_brk); 2054 2055/* Release all mmaps. */ 2056void exit_mmap(struct mm_struct *mm) 2057{ 2058 struct mmu_gather *tlb; 2059 struct vm_area_struct *vma = mm->mmap; 2060 unsigned long nr_accounted = 0; 2061 unsigned long end; 2062 2063 /* mm's last user has gone, and its about to be pulled down */ 2064 arch_exit_mmap(mm); 2065 mmu_notifier_release(mm); 2066 2067 lru_add_drain(); 2068 flush_cache_mm(mm); 2069 tlb = tlb_gather_mmu(mm, 1); 2070 /* Don't update_hiwater_rss(mm) here, do_exit already did */ 2071 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2072 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 2073 vm_unacct_memory(nr_accounted); 2074 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); 2075 tlb_finish_mmu(tlb, 0, end); 2076 2077 /* 2078 * Walk the list again, actually closing and freeing it, 2079 * with preemption enabled, without holding any MM locks. 2080 */ 2081 while (vma) 2082 vma = remove_vma(vma); 2083 2084 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2085} 2086 2087/* Insert vm structure into process list sorted by address 2088 * and into the inode's i_mmap tree. If vm_file is non-NULL 2089 * then i_mmap_lock is taken here. 2090 */ 2091int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 2092{ 2093 struct vm_area_struct * __vma, * prev; 2094 struct rb_node ** rb_link, * rb_parent; 2095 2096 /* 2097 * The vm_pgoff of a purely anonymous vma should be irrelevant 2098 * until its first write fault, when page's anon_vma and index 2099 * are set. But now set the vm_pgoff it will almost certainly 2100 * end up with (unless mremap moves it elsewhere before that 2101 * first wfault), so /proc/pid/maps tells a consistent story. 2102 * 2103 * By setting it to reflect the virtual start address of the 2104 * vma, merges and splits can happen in a seamless way, just 2105 * using the existing file pgoff checks and manipulations. 2106 * Similarly in do_mmap_pgoff and in do_brk. 2107 */ 2108 if (!vma->vm_file) { 2109 BUG_ON(vma->anon_vma); 2110 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2111 } 2112 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2113 if (__vma && __vma->vm_start < vma->vm_end) 2114 return -ENOMEM; 2115 if ((vma->vm_flags & VM_ACCOUNT) && 2116 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2117 return -ENOMEM; 2118 vma_link(mm, vma, prev, rb_link, rb_parent); 2119 return 0; 2120} 2121 2122/* 2123 * Copy the vma structure to a new location in the same mm, 2124 * prior to moving page table entries, to effect an mremap move. 2125 */ 2126struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2127 unsigned long addr, unsigned long len, pgoff_t pgoff) 2128{ 2129 struct vm_area_struct *vma = *vmap; 2130 unsigned long vma_start = vma->vm_start; 2131 struct mm_struct *mm = vma->vm_mm; 2132 struct vm_area_struct *new_vma, *prev; 2133 struct rb_node **rb_link, *rb_parent; 2134 struct mempolicy *pol; 2135 2136 /* 2137 * If anonymous vma has not yet been faulted, update new pgoff 2138 * to match new location, to increase its chance of merging. 2139 */ 2140 if (!vma->vm_file && !vma->anon_vma) 2141 pgoff = addr >> PAGE_SHIFT; 2142 2143 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2144 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2145 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2146 if (new_vma) { 2147 /* 2148 * Source vma may have been merged into new_vma 2149 */ 2150 if (vma_start >= new_vma->vm_start && 2151 vma_start < new_vma->vm_end) 2152 *vmap = new_vma; 2153 } else { 2154 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2155 if (new_vma) { 2156 *new_vma = *vma; 2157 pol = mpol_dup(vma_policy(vma)); 2158 if (IS_ERR(pol)) { 2159 kmem_cache_free(vm_area_cachep, new_vma); 2160 return NULL; 2161 } 2162 vma_set_policy(new_vma, pol); 2163 new_vma->vm_start = addr; 2164 new_vma->vm_end = addr + len; 2165 new_vma->vm_pgoff = pgoff; 2166 if (new_vma->vm_file) { 2167 get_file(new_vma->vm_file); 2168 if (vma->vm_flags & VM_EXECUTABLE) 2169 added_exe_file_vma(mm); 2170 } 2171 if (new_vma->vm_ops && new_vma->vm_ops->open) 2172 new_vma->vm_ops->open(new_vma); 2173 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2174 } 2175 } 2176 return new_vma; 2177} 2178 2179/* 2180 * Return true if the calling process may expand its vm space by the passed 2181 * number of pages 2182 */ 2183int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2184{ 2185 unsigned long cur = mm->total_vm; /* pages */ 2186 unsigned long lim; 2187 2188 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2189 2190 if (cur + npages > lim) 2191 return 0; 2192 return 1; 2193} 2194 2195 2196static int special_mapping_fault(struct vm_area_struct *vma, 2197 struct vm_fault *vmf) 2198{ 2199 pgoff_t pgoff; 2200 struct page **pages; 2201 2202 /* 2203 * special mappings have no vm_file, and in that case, the mm 2204 * uses vm_pgoff internally. So we have to subtract it from here. 2205 * We are allowed to do this because we are the mm; do not copy 2206 * this code into drivers! 2207 */ 2208 pgoff = vmf->pgoff - vma->vm_pgoff; 2209 2210 for (pages = vma->vm_private_data; pgoff && *pages; ++pages) 2211 pgoff--; 2212 2213 if (*pages) { 2214 struct page *page = *pages; 2215 get_page(page); 2216 vmf->page = page; 2217 return 0; 2218 } 2219 2220 return VM_FAULT_SIGBUS; 2221} 2222 2223/* 2224 * Having a close hook prevents vma merging regardless of flags. 2225 */ 2226static void special_mapping_close(struct vm_area_struct *vma) 2227{ 2228} 2229 2230static struct vm_operations_struct special_mapping_vmops = { 2231 .close = special_mapping_close, 2232 .fault = special_mapping_fault, 2233}; 2234 2235/* 2236 * Called with mm->mmap_sem held for writing. 2237 * Insert a new vma covering the given region, with the given flags. 2238 * Its pages are supplied by the given array of struct page *. 2239 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2240 * The region past the last page supplied will always produce SIGBUS. 2241 * The array pointer and the pages it points to are assumed to stay alive 2242 * for as long as this mapping might exist. 2243 */ 2244int install_special_mapping(struct mm_struct *mm, 2245 unsigned long addr, unsigned long len, 2246 unsigned long vm_flags, struct page **pages) 2247{ 2248 struct vm_area_struct *vma; 2249 2250 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2251 if (unlikely(vma == NULL)) 2252 return -ENOMEM; 2253 2254 vma->vm_mm = mm; 2255 vma->vm_start = addr; 2256 vma->vm_end = addr + len; 2257 2258 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; 2259 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 2260 2261 vma->vm_ops = &special_mapping_vmops; 2262 vma->vm_private_data = pages; 2263 2264 if (unlikely(insert_vm_struct(mm, vma))) { 2265 kmem_cache_free(vm_area_cachep, vma); 2266 return -ENOMEM; 2267 } 2268 2269 mm->total_vm += len >> PAGE_SHIFT; 2270 2271 return 0; 2272} 2273 2274static DEFINE_MUTEX(mm_all_locks_mutex); 2275 2276static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) 2277{ 2278 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2279 /* 2280 * The LSB of head.next can't change from under us 2281 * because we hold the mm_all_locks_mutex. 2282 */ 2283 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem); 2284 /* 2285 * We can safely modify head.next after taking the 2286 * anon_vma->lock. If some other vma in this mm shares 2287 * the same anon_vma we won't take it again. 2288 * 2289 * No need of atomic instructions here, head.next 2290 * can't change from under us thanks to the 2291 * anon_vma->lock. 2292 */ 2293 if (__test_and_set_bit(0, (unsigned long *) 2294 &anon_vma->head.next)) 2295 BUG(); 2296 } 2297} 2298 2299static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) 2300{ 2301 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2302 /* 2303 * AS_MM_ALL_LOCKS can't change from under us because 2304 * we hold the mm_all_locks_mutex. 2305 * 2306 * Operations on ->flags have to be atomic because 2307 * even if AS_MM_ALL_LOCKS is stable thanks to the 2308 * mm_all_locks_mutex, there may be other cpus 2309 * changing other bitflags in parallel to us. 2310 */ 2311 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) 2312 BUG(); 2313 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem); 2314 } 2315} 2316 2317/* 2318 * This operation locks against the VM for all pte/vma/mm related 2319 * operations that could ever happen on a certain mm. This includes 2320 * vmtruncate, try_to_unmap, and all page faults. 2321 * 2322 * The caller must take the mmap_sem in write mode before calling 2323 * mm_take_all_locks(). The caller isn't allowed to release the 2324 * mmap_sem until mm_drop_all_locks() returns. 2325 * 2326 * mmap_sem in write mode is required in order to block all operations 2327 * that could modify pagetables and free pages without need of 2328 * altering the vma layout (for example populate_range() with 2329 * nonlinear vmas). It's also needed in write mode to avoid new 2330 * anon_vmas to be associated with existing vmas. 2331 * 2332 * A single task can't take more than one mm_take_all_locks() in a row 2333 * or it would deadlock. 2334 * 2335 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in 2336 * mapping->flags avoid to take the same lock twice, if more than one 2337 * vma in this mm is backed by the same anon_vma or address_space. 2338 * 2339 * We can take all the locks in random order because the VM code 2340 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never 2341 * takes more than one of them in a row. Secondly we're protected 2342 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. 2343 * 2344 * mm_take_all_locks() and mm_drop_all_locks are expensive operations 2345 * that may have to take thousand of locks. 2346 * 2347 * mm_take_all_locks() can fail if it's interrupted by signals. 2348 */ 2349int mm_take_all_locks(struct mm_struct *mm) 2350{ 2351 struct vm_area_struct *vma; 2352 int ret = -EINTR; 2353 2354 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2355 2356 mutex_lock(&mm_all_locks_mutex); 2357 2358 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2359 if (signal_pending(current)) 2360 goto out_unlock; 2361 if (vma->vm_file && vma->vm_file->f_mapping) 2362 vm_lock_mapping(mm, vma->vm_file->f_mapping); 2363 } 2364 2365 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2366 if (signal_pending(current)) 2367 goto out_unlock; 2368 if (vma->anon_vma) 2369 vm_lock_anon_vma(mm, vma->anon_vma); 2370 } 2371 2372 ret = 0; 2373 2374out_unlock: 2375 if (ret) 2376 mm_drop_all_locks(mm); 2377 2378 return ret; 2379} 2380 2381static void vm_unlock_anon_vma(struct anon_vma *anon_vma) 2382{ 2383 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2384 /* 2385 * The LSB of head.next can't change to 0 from under 2386 * us because we hold the mm_all_locks_mutex. 2387 * 2388 * We must however clear the bitflag before unlocking 2389 * the vma so the users using the anon_vma->head will 2390 * never see our bitflag. 2391 * 2392 * No need of atomic instructions here, head.next 2393 * can't change from under us until we release the 2394 * anon_vma->lock. 2395 */ 2396 if (!__test_and_clear_bit(0, (unsigned long *) 2397 &anon_vma->head.next)) 2398 BUG(); 2399 spin_unlock(&anon_vma->lock); 2400 } 2401} 2402 2403static void vm_unlock_mapping(struct address_space *mapping) 2404{ 2405 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2406 /* 2407 * AS_MM_ALL_LOCKS can't change to 0 from under us 2408 * because we hold the mm_all_locks_mutex. 2409 */ 2410 spin_unlock(&mapping->i_mmap_lock); 2411 if (!test_and_clear_bit(AS_MM_ALL_LOCKS, 2412 &mapping->flags)) 2413 BUG(); 2414 } 2415} 2416 2417/* 2418 * The mmap_sem cannot be released by the caller until 2419 * mm_drop_all_locks() returns. 2420 */ 2421void mm_drop_all_locks(struct mm_struct *mm) 2422{ 2423 struct vm_area_struct *vma; 2424 2425 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2426 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); 2427 2428 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2429 if (vma->anon_vma) 2430 vm_unlock_anon_vma(vma->anon_vma); 2431 if (vma->vm_file && vma->vm_file->f_mapping) 2432 vm_unlock_mapping(vma->vm_file->f_mapping); 2433 } 2434 2435 mutex_unlock(&mm_all_locks_mutex); 2436} 2437