mmap.c revision 9480c53e9b2aa13a06283ffb96bb8f1873ac4e9a
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 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 if (mm) 179 allowed -= mm->total_vm / 32; 180 181 /* 182 * cast `allowed' as a signed long because vm_committed_space 183 * sometimes has a negative value 184 */ 185 if (atomic_long_read(&vm_committed_space) < (long)allowed) 186 return 0; 187error: 188 vm_unacct_memory(pages); 189 190 return -ENOMEM; 191} 192 193/* 194 * Requires inode->i_mapping->i_mmap_lock 195 */ 196static void __remove_shared_vm_struct(struct vm_area_struct *vma, 197 struct file *file, struct address_space *mapping) 198{ 199 if (vma->vm_flags & VM_DENYWRITE) 200 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 201 if (vma->vm_flags & VM_SHARED) 202 mapping->i_mmap_writable--; 203 204 flush_dcache_mmap_lock(mapping); 205 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 206 list_del_init(&vma->shared.vm_set.list); 207 else 208 vma_prio_tree_remove(vma, &mapping->i_mmap); 209 flush_dcache_mmap_unlock(mapping); 210} 211 212/* 213 * Unlink a file-based vm structure from its prio_tree, to hide 214 * vma from rmap and vmtruncate before freeing its page tables. 215 */ 216void unlink_file_vma(struct vm_area_struct *vma) 217{ 218 struct file *file = vma->vm_file; 219 220 if (file) { 221 struct address_space *mapping = file->f_mapping; 222 spin_lock(&mapping->i_mmap_lock); 223 __remove_shared_vm_struct(vma, file, mapping); 224 spin_unlock(&mapping->i_mmap_lock); 225 } 226} 227 228/* 229 * Close a vm structure and free it, returning the next. 230 */ 231static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 232{ 233 struct vm_area_struct *next = vma->vm_next; 234 235 might_sleep(); 236 if (vma->vm_ops && vma->vm_ops->close) 237 vma->vm_ops->close(vma); 238 if (vma->vm_file) { 239 fput(vma->vm_file); 240 if (vma->vm_flags & VM_EXECUTABLE) 241 removed_exe_file_vma(vma->vm_mm); 242 } 243 mpol_put(vma_policy(vma)); 244 kmem_cache_free(vm_area_cachep, vma); 245 return next; 246} 247 248SYSCALL_DEFINE1(brk, unsigned long, brk) 249{ 250 unsigned long rlim, retval; 251 unsigned long newbrk, oldbrk; 252 struct mm_struct *mm = current->mm; 253 unsigned long min_brk; 254 255 down_write(&mm->mmap_sem); 256 257#ifdef CONFIG_COMPAT_BRK 258 min_brk = mm->end_code; 259#else 260 min_brk = mm->start_brk; 261#endif 262 if (brk < min_brk) 263 goto out; 264 265 /* 266 * Check against rlimit here. If this check is done later after the test 267 * of oldbrk with newbrk then it can escape the test and let the data 268 * segment grow beyond its set limit the in case where the limit is 269 * not page aligned -Ram Gupta 270 */ 271 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 272 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + 273 (mm->end_data - mm->start_data) > rlim) 274 goto out; 275 276 newbrk = PAGE_ALIGN(brk); 277 oldbrk = PAGE_ALIGN(mm->brk); 278 if (oldbrk == newbrk) 279 goto set_brk; 280 281 /* Always allow shrinking brk. */ 282 if (brk <= mm->brk) { 283 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 284 goto set_brk; 285 goto out; 286 } 287 288 /* Check against existing mmap mappings. */ 289 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 290 goto out; 291 292 /* Ok, looks good - let it rip. */ 293 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 294 goto out; 295set_brk: 296 mm->brk = brk; 297out: 298 retval = mm->brk; 299 up_write(&mm->mmap_sem); 300 return retval; 301} 302 303#ifdef DEBUG_MM_RB 304static int browse_rb(struct rb_root *root) 305{ 306 int i = 0, j; 307 struct rb_node *nd, *pn = NULL; 308 unsigned long prev = 0, pend = 0; 309 310 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 311 struct vm_area_struct *vma; 312 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 313 if (vma->vm_start < prev) 314 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 315 if (vma->vm_start < pend) 316 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 317 if (vma->vm_start > vma->vm_end) 318 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 319 i++; 320 pn = nd; 321 prev = vma->vm_start; 322 pend = vma->vm_end; 323 } 324 j = 0; 325 for (nd = pn; nd; nd = rb_prev(nd)) { 326 j++; 327 } 328 if (i != j) 329 printk("backwards %d, forwards %d\n", j, i), i = 0; 330 return i; 331} 332 333void validate_mm(struct mm_struct *mm) 334{ 335 int bug = 0; 336 int i = 0; 337 struct vm_area_struct *tmp = mm->mmap; 338 while (tmp) { 339 tmp = tmp->vm_next; 340 i++; 341 } 342 if (i != mm->map_count) 343 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 344 i = browse_rb(&mm->mm_rb); 345 if (i != mm->map_count) 346 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 347 BUG_ON(bug); 348} 349#else 350#define validate_mm(mm) do { } while (0) 351#endif 352 353static struct vm_area_struct * 354find_vma_prepare(struct mm_struct *mm, unsigned long addr, 355 struct vm_area_struct **pprev, struct rb_node ***rb_link, 356 struct rb_node ** rb_parent) 357{ 358 struct vm_area_struct * vma; 359 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 360 361 __rb_link = &mm->mm_rb.rb_node; 362 rb_prev = __rb_parent = NULL; 363 vma = NULL; 364 365 while (*__rb_link) { 366 struct vm_area_struct *vma_tmp; 367 368 __rb_parent = *__rb_link; 369 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 370 371 if (vma_tmp->vm_end > addr) { 372 vma = vma_tmp; 373 if (vma_tmp->vm_start <= addr) 374 break; 375 __rb_link = &__rb_parent->rb_left; 376 } else { 377 rb_prev = __rb_parent; 378 __rb_link = &__rb_parent->rb_right; 379 } 380 } 381 382 *pprev = NULL; 383 if (rb_prev) 384 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 385 *rb_link = __rb_link; 386 *rb_parent = __rb_parent; 387 return vma; 388} 389 390static inline void 391__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 392 struct vm_area_struct *prev, struct rb_node *rb_parent) 393{ 394 if (prev) { 395 vma->vm_next = prev->vm_next; 396 prev->vm_next = vma; 397 } else { 398 mm->mmap = vma; 399 if (rb_parent) 400 vma->vm_next = rb_entry(rb_parent, 401 struct vm_area_struct, vm_rb); 402 else 403 vma->vm_next = NULL; 404 } 405} 406 407void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 408 struct rb_node **rb_link, struct rb_node *rb_parent) 409{ 410 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 411 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 412} 413 414static void __vma_link_file(struct vm_area_struct *vma) 415{ 416 struct file *file; 417 418 file = vma->vm_file; 419 if (file) { 420 struct address_space *mapping = file->f_mapping; 421 422 if (vma->vm_flags & VM_DENYWRITE) 423 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 424 if (vma->vm_flags & VM_SHARED) 425 mapping->i_mmap_writable++; 426 427 flush_dcache_mmap_lock(mapping); 428 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 429 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 430 else 431 vma_prio_tree_insert(vma, &mapping->i_mmap); 432 flush_dcache_mmap_unlock(mapping); 433 } 434} 435 436static void 437__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 438 struct vm_area_struct *prev, struct rb_node **rb_link, 439 struct rb_node *rb_parent) 440{ 441 __vma_link_list(mm, vma, prev, rb_parent); 442 __vma_link_rb(mm, vma, rb_link, rb_parent); 443 __anon_vma_link(vma); 444} 445 446static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 447 struct vm_area_struct *prev, struct rb_node **rb_link, 448 struct rb_node *rb_parent) 449{ 450 struct address_space *mapping = NULL; 451 452 if (vma->vm_file) 453 mapping = vma->vm_file->f_mapping; 454 455 if (mapping) { 456 spin_lock(&mapping->i_mmap_lock); 457 vma->vm_truncate_count = mapping->truncate_count; 458 } 459 anon_vma_lock(vma); 460 461 __vma_link(mm, vma, prev, rb_link, rb_parent); 462 __vma_link_file(vma); 463 464 anon_vma_unlock(vma); 465 if (mapping) 466 spin_unlock(&mapping->i_mmap_lock); 467 468 mm->map_count++; 469 validate_mm(mm); 470} 471 472/* 473 * Helper for vma_adjust in the split_vma insert case: 474 * insert vm structure into list and rbtree and anon_vma, 475 * but it has already been inserted into prio_tree earlier. 476 */ 477static void __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/* Flags that can be inherited from an existing mapping when merging */ 662#define VM_MERGEABLE_FLAGS (VM_CAN_NONLINEAR) 663 664/* 665 * If the vma has a ->close operation then the driver probably needs to release 666 * per-vma resources, so we don't attempt to merge those. 667 */ 668static inline int is_mergeable_vma(struct vm_area_struct *vma, 669 struct file *file, unsigned long vm_flags) 670{ 671 if ((vma->vm_flags ^ vm_flags) & ~VM_MERGEABLE_FLAGS) 672 return 0; 673 if (vma->vm_file != file) 674 return 0; 675 if (vma->vm_ops && vma->vm_ops->close) 676 return 0; 677 return 1; 678} 679 680static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 681 struct anon_vma *anon_vma2) 682{ 683 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 684} 685 686/* 687 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 688 * in front of (at a lower virtual address and file offset than) the vma. 689 * 690 * We cannot merge two vmas if they have differently assigned (non-NULL) 691 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 692 * 693 * We don't check here for the merged mmap wrapping around the end of pagecache 694 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 695 * wrap, nor mmaps which cover the final page at index -1UL. 696 */ 697static int 698can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 699 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 700{ 701 if (is_mergeable_vma(vma, file, vm_flags) && 702 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 703 if (vma->vm_pgoff == vm_pgoff) 704 return 1; 705 } 706 return 0; 707} 708 709/* 710 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 711 * beyond (at a higher virtual address and file offset than) the vma. 712 * 713 * We cannot merge two vmas if they have differently assigned (non-NULL) 714 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 715 */ 716static int 717can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 718 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 719{ 720 if (is_mergeable_vma(vma, file, vm_flags) && 721 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 722 pgoff_t vm_pglen; 723 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 724 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 725 return 1; 726 } 727 return 0; 728} 729 730/* 731 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 732 * whether that can be merged with its predecessor or its successor. 733 * Or both (it neatly fills a hole). 734 * 735 * In most cases - when called for mmap, brk or mremap - [addr,end) is 736 * certain not to be mapped by the time vma_merge is called; but when 737 * called for mprotect, it is certain to be already mapped (either at 738 * an offset within prev, or at the start of next), and the flags of 739 * this area are about to be changed to vm_flags - and the no-change 740 * case has already been eliminated. 741 * 742 * The following mprotect cases have to be considered, where AAAA is 743 * the area passed down from mprotect_fixup, never extending beyond one 744 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 745 * 746 * AAAA AAAA AAAA AAAA 747 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 748 * cannot merge might become might become might become 749 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 750 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 751 * mremap move: PPPPNNNNNNNN 8 752 * AAAA 753 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 754 * might become case 1 below case 2 below case 3 below 755 * 756 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 757 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 758 */ 759struct vm_area_struct *vma_merge(struct mm_struct *mm, 760 struct vm_area_struct *prev, unsigned long addr, 761 unsigned long end, unsigned long vm_flags, 762 struct anon_vma *anon_vma, struct file *file, 763 pgoff_t pgoff, struct mempolicy *policy) 764{ 765 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 766 struct vm_area_struct *area, *next; 767 768 /* 769 * We later require that vma->vm_flags == vm_flags, 770 * so this tests vma->vm_flags & VM_SPECIAL, too. 771 */ 772 if (vm_flags & VM_SPECIAL) 773 return NULL; 774 775 if (prev) 776 next = prev->vm_next; 777 else 778 next = mm->mmap; 779 area = next; 780 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 781 next = next->vm_next; 782 783 /* 784 * Can it merge with the predecessor? 785 */ 786 if (prev && prev->vm_end == addr && 787 mpol_equal(vma_policy(prev), policy) && 788 can_vma_merge_after(prev, vm_flags, 789 anon_vma, file, pgoff)) { 790 /* 791 * OK, it can. Can we now merge in the successor as well? 792 */ 793 if (next && end == next->vm_start && 794 mpol_equal(policy, vma_policy(next)) && 795 can_vma_merge_before(next, vm_flags, 796 anon_vma, file, pgoff+pglen) && 797 is_mergeable_anon_vma(prev->anon_vma, 798 next->anon_vma)) { 799 /* cases 1, 6 */ 800 vma_adjust(prev, prev->vm_start, 801 next->vm_end, prev->vm_pgoff, NULL); 802 } else /* cases 2, 5, 7 */ 803 vma_adjust(prev, prev->vm_start, 804 end, prev->vm_pgoff, NULL); 805 return prev; 806 } 807 808 /* 809 * Can this new request be merged in front of next? 810 */ 811 if (next && end == next->vm_start && 812 mpol_equal(policy, vma_policy(next)) && 813 can_vma_merge_before(next, vm_flags, 814 anon_vma, file, pgoff+pglen)) { 815 if (prev && addr < prev->vm_end) /* case 4 */ 816 vma_adjust(prev, prev->vm_start, 817 addr, prev->vm_pgoff, NULL); 818 else /* cases 3, 8 */ 819 vma_adjust(area, addr, next->vm_end, 820 next->vm_pgoff - pglen, NULL); 821 return area; 822 } 823 824 return NULL; 825} 826 827/* 828 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 829 * neighbouring vmas for a suitable anon_vma, before it goes off 830 * to allocate a new anon_vma. It checks because a repetitive 831 * sequence of mprotects and faults may otherwise lead to distinct 832 * anon_vmas being allocated, preventing vma merge in subsequent 833 * mprotect. 834 */ 835struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 836{ 837 struct vm_area_struct *near; 838 unsigned long vm_flags; 839 840 near = vma->vm_next; 841 if (!near) 842 goto try_prev; 843 844 /* 845 * Since only mprotect tries to remerge vmas, match flags 846 * which might be mprotected into each other later on. 847 * Neither mlock nor madvise tries to remerge at present, 848 * so leave their flags as obstructing a merge. 849 */ 850 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 851 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 852 853 if (near->anon_vma && vma->vm_end == near->vm_start && 854 mpol_equal(vma_policy(vma), vma_policy(near)) && 855 can_vma_merge_before(near, vm_flags, 856 NULL, vma->vm_file, vma->vm_pgoff + 857 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 858 return near->anon_vma; 859try_prev: 860 /* 861 * It is potentially slow to have to call find_vma_prev here. 862 * But it's only on the first write fault on the vma, not 863 * every time, and we could devise a way to avoid it later 864 * (e.g. stash info in next's anon_vma_node when assigning 865 * an anon_vma, or when trying vma_merge). Another time. 866 */ 867 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 868 if (!near) 869 goto none; 870 871 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 872 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 873 874 if (near->anon_vma && near->vm_end == vma->vm_start && 875 mpol_equal(vma_policy(near), vma_policy(vma)) && 876 can_vma_merge_after(near, vm_flags, 877 NULL, vma->vm_file, vma->vm_pgoff)) 878 return near->anon_vma; 879none: 880 /* 881 * There's no absolute need to look only at touching neighbours: 882 * we could search further afield for "compatible" anon_vmas. 883 * But it would probably just be a waste of time searching, 884 * or lead to too many vmas hanging off the same anon_vma. 885 * We're trying to allow mprotect remerging later on, 886 * not trying to minimize memory used for anon_vmas. 887 */ 888 return NULL; 889} 890 891#ifdef CONFIG_PROC_FS 892void vm_stat_account(struct mm_struct *mm, unsigned long flags, 893 struct file *file, long pages) 894{ 895 const unsigned long stack_flags 896 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 897 898 if (file) { 899 mm->shared_vm += pages; 900 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 901 mm->exec_vm += pages; 902 } else if (flags & stack_flags) 903 mm->stack_vm += pages; 904 if (flags & (VM_RESERVED|VM_IO)) 905 mm->reserved_vm += pages; 906} 907#endif /* CONFIG_PROC_FS */ 908 909/* 910 * The caller must hold down_write(current->mm->mmap_sem). 911 */ 912 913unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, 914 unsigned long len, unsigned long prot, 915 unsigned long flags, unsigned long pgoff) 916{ 917 struct mm_struct * mm = current->mm; 918 struct inode *inode; 919 unsigned int vm_flags; 920 int error; 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 } 975 976 /* mlock MCL_FUTURE? */ 977 if (vm_flags & VM_LOCKED) { 978 unsigned long locked, lock_limit; 979 locked = len >> PAGE_SHIFT; 980 locked += mm->locked_vm; 981 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 982 lock_limit >>= PAGE_SHIFT; 983 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 984 return -EAGAIN; 985 } 986 987 inode = file ? file->f_path.dentry->d_inode : NULL; 988 989 if (file) { 990 switch (flags & MAP_TYPE) { 991 case MAP_SHARED: 992 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 993 return -EACCES; 994 995 /* 996 * Make sure we don't allow writing to an append-only 997 * file.. 998 */ 999 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 1000 return -EACCES; 1001 1002 /* 1003 * Make sure there are no mandatory locks on the file. 1004 */ 1005 if (locks_verify_locked(inode)) 1006 return -EAGAIN; 1007 1008 vm_flags |= VM_SHARED | VM_MAYSHARE; 1009 if (!(file->f_mode & FMODE_WRITE)) 1010 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1011 1012 /* fall through */ 1013 case MAP_PRIVATE: 1014 if (!(file->f_mode & FMODE_READ)) 1015 return -EACCES; 1016 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1017 if (vm_flags & VM_EXEC) 1018 return -EPERM; 1019 vm_flags &= ~VM_MAYEXEC; 1020 } 1021 1022 if (!file->f_op || !file->f_op->mmap) 1023 return -ENODEV; 1024 break; 1025 1026 default: 1027 return -EINVAL; 1028 } 1029 } else { 1030 switch (flags & MAP_TYPE) { 1031 case MAP_SHARED: 1032 /* 1033 * Ignore pgoff. 1034 */ 1035 pgoff = 0; 1036 vm_flags |= VM_SHARED | VM_MAYSHARE; 1037 break; 1038 case MAP_PRIVATE: 1039 /* 1040 * Set pgoff according to addr for anon_vma. 1041 */ 1042 pgoff = addr >> PAGE_SHIFT; 1043 break; 1044 default: 1045 return -EINVAL; 1046 } 1047 } 1048 1049 error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1050 if (error) 1051 return error; 1052 1053 return mmap_region(file, addr, len, flags, vm_flags, pgoff); 1054} 1055EXPORT_SYMBOL(do_mmap_pgoff); 1056 1057/* 1058 * Some shared mappigns will want the pages marked read-only 1059 * to track write events. If so, we'll downgrade vm_page_prot 1060 * to the private version (using protection_map[] without the 1061 * VM_SHARED bit). 1062 */ 1063int vma_wants_writenotify(struct vm_area_struct *vma) 1064{ 1065 unsigned int vm_flags = vma->vm_flags; 1066 1067 /* If it was private or non-writable, the write bit is already clear */ 1068 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1069 return 0; 1070 1071 /* The backer wishes to know when pages are first written to? */ 1072 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1073 return 1; 1074 1075 /* The open routine did something to the protections already? */ 1076 if (pgprot_val(vma->vm_page_prot) != 1077 pgprot_val(vm_get_page_prot(vm_flags))) 1078 return 0; 1079 1080 /* Specialty mapping? */ 1081 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) 1082 return 0; 1083 1084 /* Can the mapping track the dirty pages? */ 1085 return vma->vm_file && vma->vm_file->f_mapping && 1086 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1087} 1088 1089/* 1090 * We account for memory if it's a private writeable mapping, 1091 * not hugepages and VM_NORESERVE wasn't set. 1092 */ 1093static inline int accountable_mapping(struct file *file, unsigned int vm_flags) 1094{ 1095 /* 1096 * hugetlb has its own accounting separate from the core VM 1097 * VM_HUGETLB may not be set yet so we cannot check for that flag. 1098 */ 1099 if (file && is_file_hugepages(file)) 1100 return 0; 1101 1102 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; 1103} 1104 1105unsigned long mmap_region(struct file *file, unsigned long addr, 1106 unsigned long len, unsigned long flags, 1107 unsigned int vm_flags, unsigned long pgoff) 1108{ 1109 struct mm_struct *mm = current->mm; 1110 struct vm_area_struct *vma, *prev; 1111 int correct_wcount = 0; 1112 int error; 1113 struct rb_node **rb_link, *rb_parent; 1114 unsigned long charged = 0; 1115 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; 1116 1117 /* Clear old maps */ 1118 error = -ENOMEM; 1119munmap_back: 1120 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1121 if (vma && vma->vm_start < addr + len) { 1122 if (do_munmap(mm, addr, len)) 1123 return -ENOMEM; 1124 goto munmap_back; 1125 } 1126 1127 /* Check against address space limit. */ 1128 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1129 return -ENOMEM; 1130 1131 /* 1132 * Set 'VM_NORESERVE' if we should not account for the 1133 * memory use of this mapping. 1134 */ 1135 if ((flags & MAP_NORESERVE)) { 1136 /* We honor MAP_NORESERVE if allowed to overcommit */ 1137 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) 1138 vm_flags |= VM_NORESERVE; 1139 1140 /* hugetlb applies strict overcommit unless MAP_NORESERVE */ 1141 if (file && is_file_hugepages(file)) 1142 vm_flags |= VM_NORESERVE; 1143 } 1144 1145 /* 1146 * Private writable mapping: check memory availability 1147 */ 1148 if (accountable_mapping(file, vm_flags)) { 1149 charged = len >> PAGE_SHIFT; 1150 if (security_vm_enough_memory(charged)) 1151 return -ENOMEM; 1152 vm_flags |= VM_ACCOUNT; 1153 } 1154 1155 /* 1156 * Can we just expand an old mapping? 1157 */ 1158 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL); 1159 if (vma) 1160 goto out; 1161 1162 /* 1163 * Determine the object being mapped and call the appropriate 1164 * specific mapper. the address has already been validated, but 1165 * not unmapped, but the maps are removed from the list. 1166 */ 1167 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1168 if (!vma) { 1169 error = -ENOMEM; 1170 goto unacct_error; 1171 } 1172 1173 vma->vm_mm = mm; 1174 vma->vm_start = addr; 1175 vma->vm_end = addr + len; 1176 vma->vm_flags = vm_flags; 1177 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1178 vma->vm_pgoff = pgoff; 1179 1180 if (file) { 1181 error = -EINVAL; 1182 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1183 goto free_vma; 1184 if (vm_flags & VM_DENYWRITE) { 1185 error = deny_write_access(file); 1186 if (error) 1187 goto free_vma; 1188 correct_wcount = 1; 1189 } 1190 vma->vm_file = file; 1191 get_file(file); 1192 error = file->f_op->mmap(file, vma); 1193 if (error) 1194 goto unmap_and_free_vma; 1195 if (vm_flags & VM_EXECUTABLE) 1196 added_exe_file_vma(mm); 1197 } else if (vm_flags & VM_SHARED) { 1198 error = shmem_zero_setup(vma); 1199 if (error) 1200 goto free_vma; 1201 } 1202 1203 /* Can addr have changed?? 1204 * 1205 * Answer: Yes, several device drivers can do it in their 1206 * f_op->mmap method. -DaveM 1207 */ 1208 addr = vma->vm_start; 1209 pgoff = vma->vm_pgoff; 1210 vm_flags = vma->vm_flags; 1211 1212 if (vma_wants_writenotify(vma)) 1213 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); 1214 1215 vma_link(mm, vma, prev, rb_link, rb_parent); 1216 file = vma->vm_file; 1217 1218 /* Once vma denies write, undo our temporary denial count */ 1219 if (correct_wcount) 1220 atomic_inc(&inode->i_writecount); 1221out: 1222 mm->total_vm += len >> PAGE_SHIFT; 1223 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1224 if (vm_flags & VM_LOCKED) { 1225 /* 1226 * makes pages present; downgrades, drops, reacquires mmap_sem 1227 */ 1228 long nr_pages = mlock_vma_pages_range(vma, addr, addr + len); 1229 if (nr_pages < 0) 1230 return nr_pages; /* vma gone! */ 1231 mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages; 1232 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) 1233 make_pages_present(addr, addr + len); 1234 return addr; 1235 1236unmap_and_free_vma: 1237 if (correct_wcount) 1238 atomic_inc(&inode->i_writecount); 1239 vma->vm_file = NULL; 1240 fput(file); 1241 1242 /* Undo any partial mapping done by a device driver. */ 1243 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1244 charged = 0; 1245free_vma: 1246 kmem_cache_free(vm_area_cachep, vma); 1247unacct_error: 1248 if (charged) 1249 vm_unacct_memory(charged); 1250 return error; 1251} 1252 1253/* Get an address range which is currently unmapped. 1254 * For shmat() with addr=0. 1255 * 1256 * Ugly calling convention alert: 1257 * Return value with the low bits set means error value, 1258 * ie 1259 * if (ret & ~PAGE_MASK) 1260 * error = ret; 1261 * 1262 * This function "knows" that -ENOMEM has the bits set. 1263 */ 1264#ifndef HAVE_ARCH_UNMAPPED_AREA 1265unsigned long 1266arch_get_unmapped_area(struct file *filp, unsigned long addr, 1267 unsigned long len, unsigned long pgoff, unsigned long flags) 1268{ 1269 struct mm_struct *mm = current->mm; 1270 struct vm_area_struct *vma; 1271 unsigned long start_addr; 1272 1273 if (len > TASK_SIZE) 1274 return -ENOMEM; 1275 1276 if (flags & MAP_FIXED) 1277 return addr; 1278 1279 if (addr) { 1280 addr = PAGE_ALIGN(addr); 1281 vma = find_vma(mm, addr); 1282 if (TASK_SIZE - len >= addr && 1283 (!vma || addr + len <= vma->vm_start)) 1284 return addr; 1285 } 1286 if (len > mm->cached_hole_size) { 1287 start_addr = addr = mm->free_area_cache; 1288 } else { 1289 start_addr = addr = TASK_UNMAPPED_BASE; 1290 mm->cached_hole_size = 0; 1291 } 1292 1293full_search: 1294 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1295 /* At this point: (!vma || addr < vma->vm_end). */ 1296 if (TASK_SIZE - len < addr) { 1297 /* 1298 * Start a new search - just in case we missed 1299 * some holes. 1300 */ 1301 if (start_addr != TASK_UNMAPPED_BASE) { 1302 addr = TASK_UNMAPPED_BASE; 1303 start_addr = addr; 1304 mm->cached_hole_size = 0; 1305 goto full_search; 1306 } 1307 return -ENOMEM; 1308 } 1309 if (!vma || addr + len <= vma->vm_start) { 1310 /* 1311 * Remember the place where we stopped the search: 1312 */ 1313 mm->free_area_cache = addr + len; 1314 return addr; 1315 } 1316 if (addr + mm->cached_hole_size < vma->vm_start) 1317 mm->cached_hole_size = vma->vm_start - addr; 1318 addr = vma->vm_end; 1319 } 1320} 1321#endif 1322 1323void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1324{ 1325 /* 1326 * Is this a new hole at the lowest possible address? 1327 */ 1328 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1329 mm->free_area_cache = addr; 1330 mm->cached_hole_size = ~0UL; 1331 } 1332} 1333 1334/* 1335 * This mmap-allocator allocates new areas top-down from below the 1336 * stack's low limit (the base): 1337 */ 1338#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1339unsigned long 1340arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1341 const unsigned long len, const unsigned long pgoff, 1342 const unsigned long flags) 1343{ 1344 struct vm_area_struct *vma; 1345 struct mm_struct *mm = current->mm; 1346 unsigned long addr = addr0; 1347 1348 /* requested length too big for entire address space */ 1349 if (len > TASK_SIZE) 1350 return -ENOMEM; 1351 1352 if (flags & MAP_FIXED) 1353 return addr; 1354 1355 /* requesting a specific address */ 1356 if (addr) { 1357 addr = PAGE_ALIGN(addr); 1358 vma = find_vma(mm, addr); 1359 if (TASK_SIZE - len >= addr && 1360 (!vma || addr + len <= vma->vm_start)) 1361 return addr; 1362 } 1363 1364 /* check if free_area_cache is useful for us */ 1365 if (len <= mm->cached_hole_size) { 1366 mm->cached_hole_size = 0; 1367 mm->free_area_cache = mm->mmap_base; 1368 } 1369 1370 /* either no address requested or can't fit in requested address hole */ 1371 addr = mm->free_area_cache; 1372 1373 /* make sure it can fit in the remaining address space */ 1374 if (addr > len) { 1375 vma = find_vma(mm, addr-len); 1376 if (!vma || addr <= vma->vm_start) 1377 /* remember the address as a hint for next time */ 1378 return (mm->free_area_cache = addr-len); 1379 } 1380 1381 if (mm->mmap_base < len) 1382 goto bottomup; 1383 1384 addr = mm->mmap_base-len; 1385 1386 do { 1387 /* 1388 * Lookup failure means no vma is above this address, 1389 * else if new region fits below vma->vm_start, 1390 * return with success: 1391 */ 1392 vma = find_vma(mm, addr); 1393 if (!vma || addr+len <= vma->vm_start) 1394 /* remember the address as a hint for next time */ 1395 return (mm->free_area_cache = addr); 1396 1397 /* remember the largest hole we saw so far */ 1398 if (addr + mm->cached_hole_size < vma->vm_start) 1399 mm->cached_hole_size = vma->vm_start - addr; 1400 1401 /* try just below the current vma->vm_start */ 1402 addr = vma->vm_start-len; 1403 } while (len < vma->vm_start); 1404 1405bottomup: 1406 /* 1407 * A failed mmap() very likely causes application failure, 1408 * so fall back to the bottom-up function here. This scenario 1409 * can happen with large stack limits and large mmap() 1410 * allocations. 1411 */ 1412 mm->cached_hole_size = ~0UL; 1413 mm->free_area_cache = TASK_UNMAPPED_BASE; 1414 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1415 /* 1416 * Restore the topdown base: 1417 */ 1418 mm->free_area_cache = mm->mmap_base; 1419 mm->cached_hole_size = ~0UL; 1420 1421 return addr; 1422} 1423#endif 1424 1425void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1426{ 1427 /* 1428 * Is this a new hole at the highest possible address? 1429 */ 1430 if (addr > mm->free_area_cache) 1431 mm->free_area_cache = addr; 1432 1433 /* dont allow allocations above current base */ 1434 if (mm->free_area_cache > mm->mmap_base) 1435 mm->free_area_cache = mm->mmap_base; 1436} 1437 1438unsigned long 1439get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1440 unsigned long pgoff, unsigned long flags) 1441{ 1442 unsigned long (*get_area)(struct file *, unsigned long, 1443 unsigned long, unsigned long, unsigned long); 1444 1445 get_area = current->mm->get_unmapped_area; 1446 if (file && file->f_op && file->f_op->get_unmapped_area) 1447 get_area = file->f_op->get_unmapped_area; 1448 addr = get_area(file, addr, len, pgoff, flags); 1449 if (IS_ERR_VALUE(addr)) 1450 return addr; 1451 1452 if (addr > TASK_SIZE - len) 1453 return -ENOMEM; 1454 if (addr & ~PAGE_MASK) 1455 return -EINVAL; 1456 1457 return arch_rebalance_pgtables(addr, len); 1458} 1459 1460EXPORT_SYMBOL(get_unmapped_area); 1461 1462/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1463struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 1464{ 1465 struct vm_area_struct *vma = NULL; 1466 1467 if (mm) { 1468 /* Check the cache first. */ 1469 /* (Cache hit rate is typically around 35%.) */ 1470 vma = mm->mmap_cache; 1471 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1472 struct rb_node * rb_node; 1473 1474 rb_node = mm->mm_rb.rb_node; 1475 vma = NULL; 1476 1477 while (rb_node) { 1478 struct vm_area_struct * vma_tmp; 1479 1480 vma_tmp = rb_entry(rb_node, 1481 struct vm_area_struct, vm_rb); 1482 1483 if (vma_tmp->vm_end > addr) { 1484 vma = vma_tmp; 1485 if (vma_tmp->vm_start <= addr) 1486 break; 1487 rb_node = rb_node->rb_left; 1488 } else 1489 rb_node = rb_node->rb_right; 1490 } 1491 if (vma) 1492 mm->mmap_cache = vma; 1493 } 1494 } 1495 return vma; 1496} 1497 1498EXPORT_SYMBOL(find_vma); 1499 1500/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1501struct vm_area_struct * 1502find_vma_prev(struct mm_struct *mm, unsigned long addr, 1503 struct vm_area_struct **pprev) 1504{ 1505 struct vm_area_struct *vma = NULL, *prev = NULL; 1506 struct rb_node *rb_node; 1507 if (!mm) 1508 goto out; 1509 1510 /* Guard against addr being lower than the first VMA */ 1511 vma = mm->mmap; 1512 1513 /* Go through the RB tree quickly. */ 1514 rb_node = mm->mm_rb.rb_node; 1515 1516 while (rb_node) { 1517 struct vm_area_struct *vma_tmp; 1518 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1519 1520 if (addr < vma_tmp->vm_end) { 1521 rb_node = rb_node->rb_left; 1522 } else { 1523 prev = vma_tmp; 1524 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1525 break; 1526 rb_node = rb_node->rb_right; 1527 } 1528 } 1529 1530out: 1531 *pprev = prev; 1532 return prev ? prev->vm_next : vma; 1533} 1534 1535/* 1536 * Verify that the stack growth is acceptable and 1537 * update accounting. This is shared with both the 1538 * grow-up and grow-down cases. 1539 */ 1540static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) 1541{ 1542 struct mm_struct *mm = vma->vm_mm; 1543 struct rlimit *rlim = current->signal->rlim; 1544 unsigned long new_start; 1545 1546 /* address space limit tests */ 1547 if (!may_expand_vm(mm, grow)) 1548 return -ENOMEM; 1549 1550 /* Stack limit test */ 1551 if (size > rlim[RLIMIT_STACK].rlim_cur) 1552 return -ENOMEM; 1553 1554 /* mlock limit tests */ 1555 if (vma->vm_flags & VM_LOCKED) { 1556 unsigned long locked; 1557 unsigned long limit; 1558 locked = mm->locked_vm + grow; 1559 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1560 if (locked > limit && !capable(CAP_IPC_LOCK)) 1561 return -ENOMEM; 1562 } 1563 1564 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1565 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1566 vma->vm_end - size; 1567 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1568 return -EFAULT; 1569 1570 /* 1571 * Overcommit.. This must be the final test, as it will 1572 * update security statistics. 1573 */ 1574 if (security_vm_enough_memory(grow)) 1575 return -ENOMEM; 1576 1577 /* Ok, everything looks good - let it rip */ 1578 mm->total_vm += grow; 1579 if (vma->vm_flags & VM_LOCKED) 1580 mm->locked_vm += grow; 1581 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1582 return 0; 1583} 1584 1585#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1586/* 1587 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1588 * vma is the last one with address > vma->vm_end. Have to extend vma. 1589 */ 1590#ifndef CONFIG_IA64 1591static 1592#endif 1593int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1594{ 1595 int error; 1596 1597 if (!(vma->vm_flags & VM_GROWSUP)) 1598 return -EFAULT; 1599 1600 /* 1601 * We must make sure the anon_vma is allocated 1602 * so that the anon_vma locking is not a noop. 1603 */ 1604 if (unlikely(anon_vma_prepare(vma))) 1605 return -ENOMEM; 1606 anon_vma_lock(vma); 1607 1608 /* 1609 * vma->vm_start/vm_end cannot change under us because the caller 1610 * is required to hold the mmap_sem in read mode. We need the 1611 * anon_vma lock to serialize against concurrent expand_stacks. 1612 * Also guard against wrapping around to address 0. 1613 */ 1614 if (address < PAGE_ALIGN(address+4)) 1615 address = PAGE_ALIGN(address+4); 1616 else { 1617 anon_vma_unlock(vma); 1618 return -ENOMEM; 1619 } 1620 error = 0; 1621 1622 /* Somebody else might have raced and expanded it already */ 1623 if (address > vma->vm_end) { 1624 unsigned long size, grow; 1625 1626 size = address - vma->vm_start; 1627 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1628 1629 error = acct_stack_growth(vma, size, grow); 1630 if (!error) 1631 vma->vm_end = address; 1632 } 1633 anon_vma_unlock(vma); 1634 return error; 1635} 1636#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1637 1638/* 1639 * vma is the first one with address < vma->vm_start. Have to extend vma. 1640 */ 1641static int expand_downwards(struct vm_area_struct *vma, 1642 unsigned long address) 1643{ 1644 int error; 1645 1646 /* 1647 * We must make sure the anon_vma is allocated 1648 * so that the anon_vma locking is not a noop. 1649 */ 1650 if (unlikely(anon_vma_prepare(vma))) 1651 return -ENOMEM; 1652 1653 address &= PAGE_MASK; 1654 error = security_file_mmap(NULL, 0, 0, 0, address, 1); 1655 if (error) 1656 return error; 1657 1658 anon_vma_lock(vma); 1659 1660 /* 1661 * vma->vm_start/vm_end cannot change under us because the caller 1662 * is required to hold the mmap_sem in read mode. We need the 1663 * anon_vma lock to serialize against concurrent expand_stacks. 1664 */ 1665 1666 /* Somebody else might have raced and expanded it already */ 1667 if (address < vma->vm_start) { 1668 unsigned long size, grow; 1669 1670 size = vma->vm_end - address; 1671 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1672 1673 error = acct_stack_growth(vma, size, grow); 1674 if (!error) { 1675 vma->vm_start = address; 1676 vma->vm_pgoff -= grow; 1677 } 1678 } 1679 anon_vma_unlock(vma); 1680 return error; 1681} 1682 1683int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) 1684{ 1685 return expand_downwards(vma, address); 1686} 1687 1688#ifdef CONFIG_STACK_GROWSUP 1689int expand_stack(struct vm_area_struct *vma, unsigned long address) 1690{ 1691 return expand_upwards(vma, address); 1692} 1693 1694struct vm_area_struct * 1695find_extend_vma(struct mm_struct *mm, unsigned long addr) 1696{ 1697 struct vm_area_struct *vma, *prev; 1698 1699 addr &= PAGE_MASK; 1700 vma = find_vma_prev(mm, addr, &prev); 1701 if (vma && (vma->vm_start <= addr)) 1702 return vma; 1703 if (!prev || expand_stack(prev, addr)) 1704 return NULL; 1705 if (prev->vm_flags & VM_LOCKED) { 1706 if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0) 1707 return NULL; /* vma gone! */ 1708 } 1709 return prev; 1710} 1711#else 1712int expand_stack(struct vm_area_struct *vma, unsigned long address) 1713{ 1714 return expand_downwards(vma, address); 1715} 1716 1717struct vm_area_struct * 1718find_extend_vma(struct mm_struct * mm, unsigned long addr) 1719{ 1720 struct vm_area_struct * vma; 1721 unsigned long start; 1722 1723 addr &= PAGE_MASK; 1724 vma = find_vma(mm,addr); 1725 if (!vma) 1726 return NULL; 1727 if (vma->vm_start <= addr) 1728 return vma; 1729 if (!(vma->vm_flags & VM_GROWSDOWN)) 1730 return NULL; 1731 start = vma->vm_start; 1732 if (expand_stack(vma, addr)) 1733 return NULL; 1734 if (vma->vm_flags & VM_LOCKED) { 1735 if (mlock_vma_pages_range(vma, addr, start) < 0) 1736 return NULL; /* vma gone! */ 1737 } 1738 return vma; 1739} 1740#endif 1741 1742/* 1743 * Ok - we have the memory areas we should free on the vma list, 1744 * so release them, and do the vma updates. 1745 * 1746 * Called with the mm semaphore held. 1747 */ 1748static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1749{ 1750 /* Update high watermark before we lower total_vm */ 1751 update_hiwater_vm(mm); 1752 do { 1753 long nrpages = vma_pages(vma); 1754 1755 mm->total_vm -= nrpages; 1756 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1757 vma = remove_vma(vma); 1758 } while (vma); 1759 validate_mm(mm); 1760} 1761 1762/* 1763 * Get rid of page table information in the indicated region. 1764 * 1765 * Called with the mm semaphore held. 1766 */ 1767static void unmap_region(struct mm_struct *mm, 1768 struct vm_area_struct *vma, struct vm_area_struct *prev, 1769 unsigned long start, unsigned long end) 1770{ 1771 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1772 struct mmu_gather *tlb; 1773 unsigned long nr_accounted = 0; 1774 1775 lru_add_drain(); 1776 tlb = tlb_gather_mmu(mm, 0); 1777 update_hiwater_rss(mm); 1778 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1779 vm_unacct_memory(nr_accounted); 1780 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1781 next? next->vm_start: 0); 1782 tlb_finish_mmu(tlb, start, end); 1783} 1784 1785/* 1786 * Create a list of vma's touched by the unmap, removing them from the mm's 1787 * vma list as we go.. 1788 */ 1789static void 1790detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1791 struct vm_area_struct *prev, unsigned long end) 1792{ 1793 struct vm_area_struct **insertion_point; 1794 struct vm_area_struct *tail_vma = NULL; 1795 unsigned long addr; 1796 1797 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1798 do { 1799 rb_erase(&vma->vm_rb, &mm->mm_rb); 1800 mm->map_count--; 1801 tail_vma = vma; 1802 vma = vma->vm_next; 1803 } while (vma && vma->vm_start < end); 1804 *insertion_point = vma; 1805 tail_vma->vm_next = NULL; 1806 if (mm->unmap_area == arch_unmap_area) 1807 addr = prev ? prev->vm_end : mm->mmap_base; 1808 else 1809 addr = vma ? vma->vm_start : mm->mmap_base; 1810 mm->unmap_area(mm, addr); 1811 mm->mmap_cache = NULL; /* Kill the cache. */ 1812} 1813 1814/* 1815 * Split a vma into two pieces at address 'addr', a new vma is allocated 1816 * either for the first part or the tail. 1817 */ 1818int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1819 unsigned long addr, int new_below) 1820{ 1821 struct mempolicy *pol; 1822 struct vm_area_struct *new; 1823 1824 if (is_vm_hugetlb_page(vma) && (addr & 1825 ~(huge_page_mask(hstate_vma(vma))))) 1826 return -EINVAL; 1827 1828 if (mm->map_count >= sysctl_max_map_count) 1829 return -ENOMEM; 1830 1831 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1832 if (!new) 1833 return -ENOMEM; 1834 1835 /* most fields are the same, copy all, and then fixup */ 1836 *new = *vma; 1837 1838 if (new_below) 1839 new->vm_end = addr; 1840 else { 1841 new->vm_start = addr; 1842 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1843 } 1844 1845 pol = mpol_dup(vma_policy(vma)); 1846 if (IS_ERR(pol)) { 1847 kmem_cache_free(vm_area_cachep, new); 1848 return PTR_ERR(pol); 1849 } 1850 vma_set_policy(new, pol); 1851 1852 if (new->vm_file) { 1853 get_file(new->vm_file); 1854 if (vma->vm_flags & VM_EXECUTABLE) 1855 added_exe_file_vma(mm); 1856 } 1857 1858 if (new->vm_ops && new->vm_ops->open) 1859 new->vm_ops->open(new); 1860 1861 if (new_below) 1862 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1863 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1864 else 1865 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1866 1867 return 0; 1868} 1869 1870/* Munmap is split into 2 main parts -- this part which finds 1871 * what needs doing, and the areas themselves, which do the 1872 * work. This now handles partial unmappings. 1873 * Jeremy Fitzhardinge <jeremy@goop.org> 1874 */ 1875int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1876{ 1877 unsigned long end; 1878 struct vm_area_struct *vma, *prev, *last; 1879 1880 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1881 return -EINVAL; 1882 1883 if ((len = PAGE_ALIGN(len)) == 0) 1884 return -EINVAL; 1885 1886 /* Find the first overlapping VMA */ 1887 vma = find_vma_prev(mm, start, &prev); 1888 if (!vma) 1889 return 0; 1890 /* we have start < vma->vm_end */ 1891 1892 /* if it doesn't overlap, we have nothing.. */ 1893 end = start + len; 1894 if (vma->vm_start >= end) 1895 return 0; 1896 1897 /* 1898 * If we need to split any vma, do it now to save pain later. 1899 * 1900 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1901 * unmapped vm_area_struct will remain in use: so lower split_vma 1902 * places tmp vma above, and higher split_vma places tmp vma below. 1903 */ 1904 if (start > vma->vm_start) { 1905 int error = split_vma(mm, vma, start, 0); 1906 if (error) 1907 return error; 1908 prev = vma; 1909 } 1910 1911 /* Does it split the last one? */ 1912 last = find_vma(mm, end); 1913 if (last && end > last->vm_start) { 1914 int error = split_vma(mm, last, end, 1); 1915 if (error) 1916 return error; 1917 } 1918 vma = prev? prev->vm_next: mm->mmap; 1919 1920 /* 1921 * unlock any mlock()ed ranges before detaching vmas 1922 */ 1923 if (mm->locked_vm) { 1924 struct vm_area_struct *tmp = vma; 1925 while (tmp && tmp->vm_start < end) { 1926 if (tmp->vm_flags & VM_LOCKED) { 1927 mm->locked_vm -= vma_pages(tmp); 1928 munlock_vma_pages_all(tmp); 1929 } 1930 tmp = tmp->vm_next; 1931 } 1932 } 1933 1934 /* 1935 * Remove the vma's, and unmap the actual pages 1936 */ 1937 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1938 unmap_region(mm, vma, prev, start, end); 1939 1940 /* Fix up all other VM information */ 1941 remove_vma_list(mm, vma); 1942 1943 return 0; 1944} 1945 1946EXPORT_SYMBOL(do_munmap); 1947 1948SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1949{ 1950 int ret; 1951 struct mm_struct *mm = current->mm; 1952 1953 profile_munmap(addr); 1954 1955 down_write(&mm->mmap_sem); 1956 ret = do_munmap(mm, addr, len); 1957 up_write(&mm->mmap_sem); 1958 return ret; 1959} 1960 1961static inline void verify_mm_writelocked(struct mm_struct *mm) 1962{ 1963#ifdef CONFIG_DEBUG_VM 1964 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1965 WARN_ON(1); 1966 up_read(&mm->mmap_sem); 1967 } 1968#endif 1969} 1970 1971/* 1972 * this is really a simplified "do_mmap". it only handles 1973 * anonymous maps. eventually we may be able to do some 1974 * brk-specific accounting here. 1975 */ 1976unsigned long do_brk(unsigned long addr, unsigned long len) 1977{ 1978 struct mm_struct * mm = current->mm; 1979 struct vm_area_struct * vma, * prev; 1980 unsigned long flags; 1981 struct rb_node ** rb_link, * rb_parent; 1982 pgoff_t pgoff = addr >> PAGE_SHIFT; 1983 int error; 1984 1985 len = PAGE_ALIGN(len); 1986 if (!len) 1987 return addr; 1988 1989 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1990 return -EINVAL; 1991 1992 if (is_hugepage_only_range(mm, addr, len)) 1993 return -EINVAL; 1994 1995 error = security_file_mmap(NULL, 0, 0, 0, addr, 1); 1996 if (error) 1997 return error; 1998 1999 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 2000 2001 error = arch_mmap_check(addr, len, flags); 2002 if (error) 2003 return error; 2004 2005 /* 2006 * mlock MCL_FUTURE? 2007 */ 2008 if (mm->def_flags & VM_LOCKED) { 2009 unsigned long locked, lock_limit; 2010 locked = len >> PAGE_SHIFT; 2011 locked += mm->locked_vm; 2012 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 2013 lock_limit >>= PAGE_SHIFT; 2014 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 2015 return -EAGAIN; 2016 } 2017 2018 /* 2019 * mm->mmap_sem is required to protect against another thread 2020 * changing the mappings in case we sleep. 2021 */ 2022 verify_mm_writelocked(mm); 2023 2024 /* 2025 * Clear old maps. this also does some error checking for us 2026 */ 2027 munmap_back: 2028 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2029 if (vma && vma->vm_start < addr + len) { 2030 if (do_munmap(mm, addr, len)) 2031 return -ENOMEM; 2032 goto munmap_back; 2033 } 2034 2035 /* Check against address space limits *after* clearing old maps... */ 2036 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 2037 return -ENOMEM; 2038 2039 if (mm->map_count > sysctl_max_map_count) 2040 return -ENOMEM; 2041 2042 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 2043 return -ENOMEM; 2044 2045 /* Can we just expand an old private anonymous mapping? */ 2046 vma = vma_merge(mm, prev, addr, addr + len, flags, 2047 NULL, NULL, pgoff, NULL); 2048 if (vma) 2049 goto out; 2050 2051 /* 2052 * create a vma struct for an anonymous mapping 2053 */ 2054 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2055 if (!vma) { 2056 vm_unacct_memory(len >> PAGE_SHIFT); 2057 return -ENOMEM; 2058 } 2059 2060 vma->vm_mm = mm; 2061 vma->vm_start = addr; 2062 vma->vm_end = addr + len; 2063 vma->vm_pgoff = pgoff; 2064 vma->vm_flags = flags; 2065 vma->vm_page_prot = vm_get_page_prot(flags); 2066 vma_link(mm, vma, prev, rb_link, rb_parent); 2067out: 2068 mm->total_vm += len >> PAGE_SHIFT; 2069 if (flags & VM_LOCKED) { 2070 if (!mlock_vma_pages_range(vma, addr, addr + len)) 2071 mm->locked_vm += (len >> PAGE_SHIFT); 2072 } 2073 return addr; 2074} 2075 2076EXPORT_SYMBOL(do_brk); 2077 2078/* Release all mmaps. */ 2079void exit_mmap(struct mm_struct *mm) 2080{ 2081 struct mmu_gather *tlb; 2082 struct vm_area_struct *vma; 2083 unsigned long nr_accounted = 0; 2084 unsigned long end; 2085 2086 /* mm's last user has gone, and its about to be pulled down */ 2087 mmu_notifier_release(mm); 2088 2089 if (mm->locked_vm) { 2090 vma = mm->mmap; 2091 while (vma) { 2092 if (vma->vm_flags & VM_LOCKED) 2093 munlock_vma_pages_all(vma); 2094 vma = vma->vm_next; 2095 } 2096 } 2097 2098 arch_exit_mmap(mm); 2099 2100 vma = mm->mmap; 2101 if (!vma) /* Can happen if dup_mmap() received an OOM */ 2102 return; 2103 2104 lru_add_drain(); 2105 flush_cache_mm(mm); 2106 tlb = tlb_gather_mmu(mm, 1); 2107 /* update_hiwater_rss(mm) here? but nobody should be looking */ 2108 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2109 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 2110 vm_unacct_memory(nr_accounted); 2111 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); 2112 tlb_finish_mmu(tlb, 0, end); 2113 2114 /* 2115 * Walk the list again, actually closing and freeing it, 2116 * with preemption enabled, without holding any MM locks. 2117 */ 2118 while (vma) 2119 vma = remove_vma(vma); 2120 2121 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2122} 2123 2124/* Insert vm structure into process list sorted by address 2125 * and into the inode's i_mmap tree. If vm_file is non-NULL 2126 * then i_mmap_lock is taken here. 2127 */ 2128int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 2129{ 2130 struct vm_area_struct * __vma, * prev; 2131 struct rb_node ** rb_link, * rb_parent; 2132 2133 /* 2134 * The vm_pgoff of a purely anonymous vma should be irrelevant 2135 * until its first write fault, when page's anon_vma and index 2136 * are set. But now set the vm_pgoff it will almost certainly 2137 * end up with (unless mremap moves it elsewhere before that 2138 * first wfault), so /proc/pid/maps tells a consistent story. 2139 * 2140 * By setting it to reflect the virtual start address of the 2141 * vma, merges and splits can happen in a seamless way, just 2142 * using the existing file pgoff checks and manipulations. 2143 * Similarly in do_mmap_pgoff and in do_brk. 2144 */ 2145 if (!vma->vm_file) { 2146 BUG_ON(vma->anon_vma); 2147 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2148 } 2149 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2150 if (__vma && __vma->vm_start < vma->vm_end) 2151 return -ENOMEM; 2152 if ((vma->vm_flags & VM_ACCOUNT) && 2153 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2154 return -ENOMEM; 2155 vma_link(mm, vma, prev, rb_link, rb_parent); 2156 return 0; 2157} 2158 2159/* 2160 * Copy the vma structure to a new location in the same mm, 2161 * prior to moving page table entries, to effect an mremap move. 2162 */ 2163struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2164 unsigned long addr, unsigned long len, pgoff_t pgoff) 2165{ 2166 struct vm_area_struct *vma = *vmap; 2167 unsigned long vma_start = vma->vm_start; 2168 struct mm_struct *mm = vma->vm_mm; 2169 struct vm_area_struct *new_vma, *prev; 2170 struct rb_node **rb_link, *rb_parent; 2171 struct mempolicy *pol; 2172 2173 /* 2174 * If anonymous vma has not yet been faulted, update new pgoff 2175 * to match new location, to increase its chance of merging. 2176 */ 2177 if (!vma->vm_file && !vma->anon_vma) 2178 pgoff = addr >> PAGE_SHIFT; 2179 2180 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2181 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2182 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2183 if (new_vma) { 2184 /* 2185 * Source vma may have been merged into new_vma 2186 */ 2187 if (vma_start >= new_vma->vm_start && 2188 vma_start < new_vma->vm_end) 2189 *vmap = new_vma; 2190 } else { 2191 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2192 if (new_vma) { 2193 *new_vma = *vma; 2194 pol = mpol_dup(vma_policy(vma)); 2195 if (IS_ERR(pol)) { 2196 kmem_cache_free(vm_area_cachep, new_vma); 2197 return NULL; 2198 } 2199 vma_set_policy(new_vma, pol); 2200 new_vma->vm_start = addr; 2201 new_vma->vm_end = addr + len; 2202 new_vma->vm_pgoff = pgoff; 2203 if (new_vma->vm_file) { 2204 get_file(new_vma->vm_file); 2205 if (vma->vm_flags & VM_EXECUTABLE) 2206 added_exe_file_vma(mm); 2207 } 2208 if (new_vma->vm_ops && new_vma->vm_ops->open) 2209 new_vma->vm_ops->open(new_vma); 2210 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2211 } 2212 } 2213 return new_vma; 2214} 2215 2216/* 2217 * Return true if the calling process may expand its vm space by the passed 2218 * number of pages 2219 */ 2220int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2221{ 2222 unsigned long cur = mm->total_vm; /* pages */ 2223 unsigned long lim; 2224 2225 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2226 2227 if (cur + npages > lim) 2228 return 0; 2229 return 1; 2230} 2231 2232 2233static int special_mapping_fault(struct vm_area_struct *vma, 2234 struct vm_fault *vmf) 2235{ 2236 pgoff_t pgoff; 2237 struct page **pages; 2238 2239 /* 2240 * special mappings have no vm_file, and in that case, the mm 2241 * uses vm_pgoff internally. So we have to subtract it from here. 2242 * We are allowed to do this because we are the mm; do not copy 2243 * this code into drivers! 2244 */ 2245 pgoff = vmf->pgoff - vma->vm_pgoff; 2246 2247 for (pages = vma->vm_private_data; pgoff && *pages; ++pages) 2248 pgoff--; 2249 2250 if (*pages) { 2251 struct page *page = *pages; 2252 get_page(page); 2253 vmf->page = page; 2254 return 0; 2255 } 2256 2257 return VM_FAULT_SIGBUS; 2258} 2259 2260/* 2261 * Having a close hook prevents vma merging regardless of flags. 2262 */ 2263static void special_mapping_close(struct vm_area_struct *vma) 2264{ 2265} 2266 2267static struct vm_operations_struct special_mapping_vmops = { 2268 .close = special_mapping_close, 2269 .fault = special_mapping_fault, 2270}; 2271 2272/* 2273 * Called with mm->mmap_sem held for writing. 2274 * Insert a new vma covering the given region, with the given flags. 2275 * Its pages are supplied by the given array of struct page *. 2276 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2277 * The region past the last page supplied will always produce SIGBUS. 2278 * The array pointer and the pages it points to are assumed to stay alive 2279 * for as long as this mapping might exist. 2280 */ 2281int install_special_mapping(struct mm_struct *mm, 2282 unsigned long addr, unsigned long len, 2283 unsigned long vm_flags, struct page **pages) 2284{ 2285 struct vm_area_struct *vma; 2286 2287 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2288 if (unlikely(vma == NULL)) 2289 return -ENOMEM; 2290 2291 vma->vm_mm = mm; 2292 vma->vm_start = addr; 2293 vma->vm_end = addr + len; 2294 2295 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; 2296 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 2297 2298 vma->vm_ops = &special_mapping_vmops; 2299 vma->vm_private_data = pages; 2300 2301 if (unlikely(insert_vm_struct(mm, vma))) { 2302 kmem_cache_free(vm_area_cachep, vma); 2303 return -ENOMEM; 2304 } 2305 2306 mm->total_vm += len >> PAGE_SHIFT; 2307 2308 return 0; 2309} 2310 2311static DEFINE_MUTEX(mm_all_locks_mutex); 2312 2313static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) 2314{ 2315 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2316 /* 2317 * The LSB of head.next can't change from under us 2318 * because we hold the mm_all_locks_mutex. 2319 */ 2320 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem); 2321 /* 2322 * We can safely modify head.next after taking the 2323 * anon_vma->lock. If some other vma in this mm shares 2324 * the same anon_vma we won't take it again. 2325 * 2326 * No need of atomic instructions here, head.next 2327 * can't change from under us thanks to the 2328 * anon_vma->lock. 2329 */ 2330 if (__test_and_set_bit(0, (unsigned long *) 2331 &anon_vma->head.next)) 2332 BUG(); 2333 } 2334} 2335 2336static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) 2337{ 2338 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2339 /* 2340 * AS_MM_ALL_LOCKS can't change from under us because 2341 * we hold the mm_all_locks_mutex. 2342 * 2343 * Operations on ->flags have to be atomic because 2344 * even if AS_MM_ALL_LOCKS is stable thanks to the 2345 * mm_all_locks_mutex, there may be other cpus 2346 * changing other bitflags in parallel to us. 2347 */ 2348 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) 2349 BUG(); 2350 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem); 2351 } 2352} 2353 2354/* 2355 * This operation locks against the VM for all pte/vma/mm related 2356 * operations that could ever happen on a certain mm. This includes 2357 * vmtruncate, try_to_unmap, and all page faults. 2358 * 2359 * The caller must take the mmap_sem in write mode before calling 2360 * mm_take_all_locks(). The caller isn't allowed to release the 2361 * mmap_sem until mm_drop_all_locks() returns. 2362 * 2363 * mmap_sem in write mode is required in order to block all operations 2364 * that could modify pagetables and free pages without need of 2365 * altering the vma layout (for example populate_range() with 2366 * nonlinear vmas). It's also needed in write mode to avoid new 2367 * anon_vmas to be associated with existing vmas. 2368 * 2369 * A single task can't take more than one mm_take_all_locks() in a row 2370 * or it would deadlock. 2371 * 2372 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in 2373 * mapping->flags avoid to take the same lock twice, if more than one 2374 * vma in this mm is backed by the same anon_vma or address_space. 2375 * 2376 * We can take all the locks in random order because the VM code 2377 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never 2378 * takes more than one of them in a row. Secondly we're protected 2379 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. 2380 * 2381 * mm_take_all_locks() and mm_drop_all_locks are expensive operations 2382 * that may have to take thousand of locks. 2383 * 2384 * mm_take_all_locks() can fail if it's interrupted by signals. 2385 */ 2386int mm_take_all_locks(struct mm_struct *mm) 2387{ 2388 struct vm_area_struct *vma; 2389 int ret = -EINTR; 2390 2391 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2392 2393 mutex_lock(&mm_all_locks_mutex); 2394 2395 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2396 if (signal_pending(current)) 2397 goto out_unlock; 2398 if (vma->vm_file && vma->vm_file->f_mapping) 2399 vm_lock_mapping(mm, vma->vm_file->f_mapping); 2400 } 2401 2402 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2403 if (signal_pending(current)) 2404 goto out_unlock; 2405 if (vma->anon_vma) 2406 vm_lock_anon_vma(mm, vma->anon_vma); 2407 } 2408 2409 ret = 0; 2410 2411out_unlock: 2412 if (ret) 2413 mm_drop_all_locks(mm); 2414 2415 return ret; 2416} 2417 2418static void vm_unlock_anon_vma(struct anon_vma *anon_vma) 2419{ 2420 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2421 /* 2422 * The LSB of head.next can't change to 0 from under 2423 * us because we hold the mm_all_locks_mutex. 2424 * 2425 * We must however clear the bitflag before unlocking 2426 * the vma so the users using the anon_vma->head will 2427 * never see our bitflag. 2428 * 2429 * No need of atomic instructions here, head.next 2430 * can't change from under us until we release the 2431 * anon_vma->lock. 2432 */ 2433 if (!__test_and_clear_bit(0, (unsigned long *) 2434 &anon_vma->head.next)) 2435 BUG(); 2436 spin_unlock(&anon_vma->lock); 2437 } 2438} 2439 2440static void vm_unlock_mapping(struct address_space *mapping) 2441{ 2442 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2443 /* 2444 * AS_MM_ALL_LOCKS can't change to 0 from under us 2445 * because we hold the mm_all_locks_mutex. 2446 */ 2447 spin_unlock(&mapping->i_mmap_lock); 2448 if (!test_and_clear_bit(AS_MM_ALL_LOCKS, 2449 &mapping->flags)) 2450 BUG(); 2451 } 2452} 2453 2454/* 2455 * The mmap_sem cannot be released by the caller until 2456 * mm_drop_all_locks() returns. 2457 */ 2458void mm_drop_all_locks(struct mm_struct *mm) 2459{ 2460 struct vm_area_struct *vma; 2461 2462 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2463 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); 2464 2465 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2466 if (vma->anon_vma) 2467 vm_unlock_anon_vma(vma->anon_vma); 2468 if (vma->vm_file && vma->vm_file->f_mapping) 2469 vm_unlock_mapping(vma->vm_file->f_mapping); 2470 } 2471 2472 mutex_unlock(&mm_all_locks_mutex); 2473} 2474 2475/* 2476 * initialise the VMA slab 2477 */ 2478void __init mmap_init(void) 2479{ 2480 vm_area_cachep = kmem_cache_create("vm_area_struct", 2481 sizeof(struct vm_area_struct), 0, 2482 SLAB_PANIC, NULL); 2483} 2484