mmap.c revision 7cd94146cd504016315608e297219f9fb7b1413b
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 30#include <asm/uaccess.h> 31#include <asm/cacheflush.h> 32#include <asm/tlb.h> 33#include <asm/mmu_context.h> 34 35#ifndef arch_mmap_check 36#define arch_mmap_check(addr, len, flags) (0) 37#endif 38 39static void unmap_region(struct mm_struct *mm, 40 struct vm_area_struct *vma, struct vm_area_struct *prev, 41 unsigned long start, unsigned long end); 42 43/* 44 * WARNING: the debugging will use recursive algorithms so never enable this 45 * unless you know what you are doing. 46 */ 47#undef DEBUG_MM_RB 48 49/* description of effects of mapping type and prot in current implementation. 50 * this is due to the limited x86 page protection hardware. The expected 51 * behavior is in parens: 52 * 53 * map_type prot 54 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 55 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 56 * w: (no) no w: (no) no w: (yes) yes w: (no) no 57 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 58 * 59 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 60 * w: (no) no w: (no) no w: (copy) copy w: (no) no 61 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 62 * 63 */ 64pgprot_t protection_map[16] = { 65 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 66 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 67}; 68 69pgprot_t vm_get_page_prot(unsigned long vm_flags) 70{ 71 return protection_map[vm_flags & 72 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; 73} 74EXPORT_SYMBOL(vm_get_page_prot); 75 76int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 77int sysctl_overcommit_ratio = 50; /* default is 50% */ 78int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 79atomic_t vm_committed_space = ATOMIC_INIT(0); 80 81/* 82 * Check that a process has enough memory to allocate a new virtual 83 * mapping. 0 means there is enough memory for the allocation to 84 * succeed and -ENOMEM implies there is not. 85 * 86 * We currently support three overcommit policies, which are set via the 87 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 88 * 89 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 90 * Additional code 2002 Jul 20 by Robert Love. 91 * 92 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 93 * 94 * Note this is a helper function intended to be used by LSMs which 95 * wish to use this logic. 96 */ 97int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 98{ 99 unsigned long free, allowed; 100 101 vm_acct_memory(pages); 102 103 /* 104 * Sometimes we want to use more memory than we have 105 */ 106 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 107 return 0; 108 109 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 110 unsigned long n; 111 112 free = global_page_state(NR_FILE_PAGES); 113 free += nr_swap_pages; 114 115 /* 116 * Any slabs which are created with the 117 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 118 * which are reclaimable, under pressure. The dentry 119 * cache and most inode caches should fall into this 120 */ 121 free += global_page_state(NR_SLAB_RECLAIMABLE); 122 123 /* 124 * Leave the last 3% for root 125 */ 126 if (!cap_sys_admin) 127 free -= free / 32; 128 129 if (free > pages) 130 return 0; 131 132 /* 133 * nr_free_pages() is very expensive on large systems, 134 * only call if we're about to fail. 135 */ 136 n = nr_free_pages(); 137 138 /* 139 * Leave reserved pages. The pages are not for anonymous pages. 140 */ 141 if (n <= totalreserve_pages) 142 goto error; 143 else 144 n -= totalreserve_pages; 145 146 /* 147 * Leave the last 3% for root 148 */ 149 if (!cap_sys_admin) 150 n -= n / 32; 151 free += n; 152 153 if (free > pages) 154 return 0; 155 156 goto error; 157 } 158 159 allowed = (totalram_pages - hugetlb_total_pages()) 160 * sysctl_overcommit_ratio / 100; 161 /* 162 * Leave the last 3% for root 163 */ 164 if (!cap_sys_admin) 165 allowed -= allowed / 32; 166 allowed += total_swap_pages; 167 168 /* Don't let a single process grow too big: 169 leave 3% of the size of this process for other processes */ 170 allowed -= mm->total_vm / 32; 171 172 /* 173 * cast `allowed' as a signed long because vm_committed_space 174 * sometimes has a negative value 175 */ 176 if (atomic_read(&vm_committed_space) < (long)allowed) 177 return 0; 178error: 179 vm_unacct_memory(pages); 180 181 return -ENOMEM; 182} 183 184/* 185 * Requires inode->i_mapping->i_mmap_lock 186 */ 187static void __remove_shared_vm_struct(struct vm_area_struct *vma, 188 struct file *file, struct address_space *mapping) 189{ 190 if (vma->vm_flags & VM_DENYWRITE) 191 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 192 if (vma->vm_flags & VM_SHARED) 193 mapping->i_mmap_writable--; 194 195 flush_dcache_mmap_lock(mapping); 196 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 197 list_del_init(&vma->shared.vm_set.list); 198 else 199 vma_prio_tree_remove(vma, &mapping->i_mmap); 200 flush_dcache_mmap_unlock(mapping); 201} 202 203/* 204 * Unlink a file-based vm structure from its prio_tree, to hide 205 * vma from rmap and vmtruncate before freeing its page tables. 206 */ 207void unlink_file_vma(struct vm_area_struct *vma) 208{ 209 struct file *file = vma->vm_file; 210 211 if (file) { 212 struct address_space *mapping = file->f_mapping; 213 spin_lock(&mapping->i_mmap_lock); 214 __remove_shared_vm_struct(vma, file, mapping); 215 spin_unlock(&mapping->i_mmap_lock); 216 } 217} 218 219/* 220 * Close a vm structure and free it, returning the next. 221 */ 222static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 223{ 224 struct vm_area_struct *next = vma->vm_next; 225 226 might_sleep(); 227 if (vma->vm_ops && vma->vm_ops->close) 228 vma->vm_ops->close(vma); 229 if (vma->vm_file) 230 fput(vma->vm_file); 231 mpol_free(vma_policy(vma)); 232 kmem_cache_free(vm_area_cachep, vma); 233 return next; 234} 235 236asmlinkage unsigned long sys_brk(unsigned long brk) 237{ 238 unsigned long rlim, retval; 239 unsigned long newbrk, oldbrk; 240 struct mm_struct *mm = current->mm; 241 242 down_write(&mm->mmap_sem); 243 244 if (brk < mm->end_code) 245 goto out; 246 247 /* 248 * Check against rlimit here. If this check is done later after the test 249 * of oldbrk with newbrk then it can escape the test and let the data 250 * segment grow beyond its set limit the in case where the limit is 251 * not page aligned -Ram Gupta 252 */ 253 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 254 if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) 255 goto out; 256 257 newbrk = PAGE_ALIGN(brk); 258 oldbrk = PAGE_ALIGN(mm->brk); 259 if (oldbrk == newbrk) 260 goto set_brk; 261 262 /* Always allow shrinking brk. */ 263 if (brk <= mm->brk) { 264 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 265 goto set_brk; 266 goto out; 267 } 268 269 /* Check against existing mmap mappings. */ 270 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 271 goto out; 272 273 /* Ok, looks good - let it rip. */ 274 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 275 goto out; 276set_brk: 277 mm->brk = brk; 278out: 279 retval = mm->brk; 280 up_write(&mm->mmap_sem); 281 return retval; 282} 283 284#ifdef DEBUG_MM_RB 285static int browse_rb(struct rb_root *root) 286{ 287 int i = 0, j; 288 struct rb_node *nd, *pn = NULL; 289 unsigned long prev = 0, pend = 0; 290 291 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 292 struct vm_area_struct *vma; 293 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 294 if (vma->vm_start < prev) 295 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 296 if (vma->vm_start < pend) 297 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 298 if (vma->vm_start > vma->vm_end) 299 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 300 i++; 301 pn = nd; 302 prev = vma->vm_start; 303 pend = vma->vm_end; 304 } 305 j = 0; 306 for (nd = pn; nd; nd = rb_prev(nd)) { 307 j++; 308 } 309 if (i != j) 310 printk("backwards %d, forwards %d\n", j, i), i = 0; 311 return i; 312} 313 314void validate_mm(struct mm_struct *mm) 315{ 316 int bug = 0; 317 int i = 0; 318 struct vm_area_struct *tmp = mm->mmap; 319 while (tmp) { 320 tmp = tmp->vm_next; 321 i++; 322 } 323 if (i != mm->map_count) 324 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 325 i = browse_rb(&mm->mm_rb); 326 if (i != mm->map_count) 327 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 328 BUG_ON(bug); 329} 330#else 331#define validate_mm(mm) do { } while (0) 332#endif 333 334static struct vm_area_struct * 335find_vma_prepare(struct mm_struct *mm, unsigned long addr, 336 struct vm_area_struct **pprev, struct rb_node ***rb_link, 337 struct rb_node ** rb_parent) 338{ 339 struct vm_area_struct * vma; 340 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 341 342 __rb_link = &mm->mm_rb.rb_node; 343 rb_prev = __rb_parent = NULL; 344 vma = NULL; 345 346 while (*__rb_link) { 347 struct vm_area_struct *vma_tmp; 348 349 __rb_parent = *__rb_link; 350 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 351 352 if (vma_tmp->vm_end > addr) { 353 vma = vma_tmp; 354 if (vma_tmp->vm_start <= addr) 355 return vma; 356 __rb_link = &__rb_parent->rb_left; 357 } else { 358 rb_prev = __rb_parent; 359 __rb_link = &__rb_parent->rb_right; 360 } 361 } 362 363 *pprev = NULL; 364 if (rb_prev) 365 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 366 *rb_link = __rb_link; 367 *rb_parent = __rb_parent; 368 return vma; 369} 370 371static inline void 372__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 373 struct vm_area_struct *prev, struct rb_node *rb_parent) 374{ 375 if (prev) { 376 vma->vm_next = prev->vm_next; 377 prev->vm_next = vma; 378 } else { 379 mm->mmap = vma; 380 if (rb_parent) 381 vma->vm_next = rb_entry(rb_parent, 382 struct vm_area_struct, vm_rb); 383 else 384 vma->vm_next = NULL; 385 } 386} 387 388void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 389 struct rb_node **rb_link, struct rb_node *rb_parent) 390{ 391 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 392 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 393} 394 395static inline void __vma_link_file(struct vm_area_struct *vma) 396{ 397 struct file * file; 398 399 file = vma->vm_file; 400 if (file) { 401 struct address_space *mapping = file->f_mapping; 402 403 if (vma->vm_flags & VM_DENYWRITE) 404 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 405 if (vma->vm_flags & VM_SHARED) 406 mapping->i_mmap_writable++; 407 408 flush_dcache_mmap_lock(mapping); 409 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 410 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 411 else 412 vma_prio_tree_insert(vma, &mapping->i_mmap); 413 flush_dcache_mmap_unlock(mapping); 414 } 415} 416 417static void 418__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 419 struct vm_area_struct *prev, struct rb_node **rb_link, 420 struct rb_node *rb_parent) 421{ 422 __vma_link_list(mm, vma, prev, rb_parent); 423 __vma_link_rb(mm, vma, rb_link, rb_parent); 424 __anon_vma_link(vma); 425} 426 427static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 428 struct vm_area_struct *prev, struct rb_node **rb_link, 429 struct rb_node *rb_parent) 430{ 431 struct address_space *mapping = NULL; 432 433 if (vma->vm_file) 434 mapping = vma->vm_file->f_mapping; 435 436 if (mapping) { 437 spin_lock(&mapping->i_mmap_lock); 438 vma->vm_truncate_count = mapping->truncate_count; 439 } 440 anon_vma_lock(vma); 441 442 __vma_link(mm, vma, prev, rb_link, rb_parent); 443 __vma_link_file(vma); 444 445 anon_vma_unlock(vma); 446 if (mapping) 447 spin_unlock(&mapping->i_mmap_lock); 448 449 mm->map_count++; 450 validate_mm(mm); 451} 452 453/* 454 * Helper for vma_adjust in the split_vma insert case: 455 * insert vm structure into list and rbtree and anon_vma, 456 * but it has already been inserted into prio_tree earlier. 457 */ 458static void 459__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 460{ 461 struct vm_area_struct * __vma, * prev; 462 struct rb_node ** rb_link, * rb_parent; 463 464 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 465 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 466 __vma_link(mm, vma, prev, rb_link, rb_parent); 467 mm->map_count++; 468} 469 470static inline void 471__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 472 struct vm_area_struct *prev) 473{ 474 prev->vm_next = vma->vm_next; 475 rb_erase(&vma->vm_rb, &mm->mm_rb); 476 if (mm->mmap_cache == vma) 477 mm->mmap_cache = prev; 478} 479 480/* 481 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 482 * is already present in an i_mmap tree without adjusting the tree. 483 * The following helper function should be used when such adjustments 484 * are necessary. The "insert" vma (if any) is to be inserted 485 * before we drop the necessary locks. 486 */ 487void vma_adjust(struct vm_area_struct *vma, unsigned long start, 488 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 489{ 490 struct mm_struct *mm = vma->vm_mm; 491 struct vm_area_struct *next = vma->vm_next; 492 struct vm_area_struct *importer = NULL; 493 struct address_space *mapping = NULL; 494 struct prio_tree_root *root = NULL; 495 struct file *file = vma->vm_file; 496 struct anon_vma *anon_vma = NULL; 497 long adjust_next = 0; 498 int remove_next = 0; 499 500 if (next && !insert) { 501 if (end >= next->vm_end) { 502 /* 503 * vma expands, overlapping all the next, and 504 * perhaps the one after too (mprotect case 6). 505 */ 506again: remove_next = 1 + (end > next->vm_end); 507 end = next->vm_end; 508 anon_vma = next->anon_vma; 509 importer = vma; 510 } else if (end > next->vm_start) { 511 /* 512 * vma expands, overlapping part of the next: 513 * mprotect case 5 shifting the boundary up. 514 */ 515 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 516 anon_vma = next->anon_vma; 517 importer = vma; 518 } else if (end < vma->vm_end) { 519 /* 520 * vma shrinks, and !insert tells it's not 521 * split_vma inserting another: so it must be 522 * mprotect case 4 shifting the boundary down. 523 */ 524 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 525 anon_vma = next->anon_vma; 526 importer = next; 527 } 528 } 529 530 if (file) { 531 mapping = file->f_mapping; 532 if (!(vma->vm_flags & VM_NONLINEAR)) 533 root = &mapping->i_mmap; 534 spin_lock(&mapping->i_mmap_lock); 535 if (importer && 536 vma->vm_truncate_count != next->vm_truncate_count) { 537 /* 538 * unmap_mapping_range might be in progress: 539 * ensure that the expanding vma is rescanned. 540 */ 541 importer->vm_truncate_count = 0; 542 } 543 if (insert) { 544 insert->vm_truncate_count = vma->vm_truncate_count; 545 /* 546 * Put into prio_tree now, so instantiated pages 547 * are visible to arm/parisc __flush_dcache_page 548 * throughout; but we cannot insert into address 549 * space until vma start or end is updated. 550 */ 551 __vma_link_file(insert); 552 } 553 } 554 555 /* 556 * When changing only vma->vm_end, we don't really need 557 * anon_vma lock: but is that case worth optimizing out? 558 */ 559 if (vma->anon_vma) 560 anon_vma = vma->anon_vma; 561 if (anon_vma) { 562 spin_lock(&anon_vma->lock); 563 /* 564 * Easily overlooked: when mprotect shifts the boundary, 565 * make sure the expanding vma has anon_vma set if the 566 * shrinking vma had, to cover any anon pages imported. 567 */ 568 if (importer && !importer->anon_vma) { 569 importer->anon_vma = anon_vma; 570 __anon_vma_link(importer); 571 } 572 } 573 574 if (root) { 575 flush_dcache_mmap_lock(mapping); 576 vma_prio_tree_remove(vma, root); 577 if (adjust_next) 578 vma_prio_tree_remove(next, root); 579 } 580 581 vma->vm_start = start; 582 vma->vm_end = end; 583 vma->vm_pgoff = pgoff; 584 if (adjust_next) { 585 next->vm_start += adjust_next << PAGE_SHIFT; 586 next->vm_pgoff += adjust_next; 587 } 588 589 if (root) { 590 if (adjust_next) 591 vma_prio_tree_insert(next, root); 592 vma_prio_tree_insert(vma, root); 593 flush_dcache_mmap_unlock(mapping); 594 } 595 596 if (remove_next) { 597 /* 598 * vma_merge has merged next into vma, and needs 599 * us to remove next before dropping the locks. 600 */ 601 __vma_unlink(mm, next, vma); 602 if (file) 603 __remove_shared_vm_struct(next, file, mapping); 604 if (next->anon_vma) 605 __anon_vma_merge(vma, next); 606 } else if (insert) { 607 /* 608 * split_vma has split insert from vma, and needs 609 * us to insert it before dropping the locks 610 * (it may either follow vma or precede it). 611 */ 612 __insert_vm_struct(mm, insert); 613 } 614 615 if (anon_vma) 616 spin_unlock(&anon_vma->lock); 617 if (mapping) 618 spin_unlock(&mapping->i_mmap_lock); 619 620 if (remove_next) { 621 if (file) 622 fput(file); 623 mm->map_count--; 624 mpol_free(vma_policy(next)); 625 kmem_cache_free(vm_area_cachep, next); 626 /* 627 * In mprotect's case 6 (see comments on vma_merge), 628 * we must remove another next too. It would clutter 629 * up the code too much to do both in one go. 630 */ 631 if (remove_next == 2) { 632 next = vma->vm_next; 633 goto again; 634 } 635 } 636 637 validate_mm(mm); 638} 639 640/* 641 * If the vma has a ->close operation then the driver probably needs to release 642 * per-vma resources, so we don't attempt to merge those. 643 */ 644#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) 645 646static inline int is_mergeable_vma(struct vm_area_struct *vma, 647 struct file *file, unsigned long vm_flags) 648{ 649 if (vma->vm_flags != vm_flags) 650 return 0; 651 if (vma->vm_file != file) 652 return 0; 653 if (vma->vm_ops && vma->vm_ops->close) 654 return 0; 655 return 1; 656} 657 658static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 659 struct anon_vma *anon_vma2) 660{ 661 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 662} 663 664/* 665 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 666 * in front of (at a lower virtual address and file offset than) the vma. 667 * 668 * We cannot merge two vmas if they have differently assigned (non-NULL) 669 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 670 * 671 * We don't check here for the merged mmap wrapping around the end of pagecache 672 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 673 * wrap, nor mmaps which cover the final page at index -1UL. 674 */ 675static int 676can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 677 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 678{ 679 if (is_mergeable_vma(vma, file, vm_flags) && 680 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 681 if (vma->vm_pgoff == vm_pgoff) 682 return 1; 683 } 684 return 0; 685} 686 687/* 688 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 689 * beyond (at a higher virtual address and file offset than) the vma. 690 * 691 * We cannot merge two vmas if they have differently assigned (non-NULL) 692 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 693 */ 694static int 695can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 696 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 697{ 698 if (is_mergeable_vma(vma, file, vm_flags) && 699 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 700 pgoff_t vm_pglen; 701 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 702 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 703 return 1; 704 } 705 return 0; 706} 707 708/* 709 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 710 * whether that can be merged with its predecessor or its successor. 711 * Or both (it neatly fills a hole). 712 * 713 * In most cases - when called for mmap, brk or mremap - [addr,end) is 714 * certain not to be mapped by the time vma_merge is called; but when 715 * called for mprotect, it is certain to be already mapped (either at 716 * an offset within prev, or at the start of next), and the flags of 717 * this area are about to be changed to vm_flags - and the no-change 718 * case has already been eliminated. 719 * 720 * The following mprotect cases have to be considered, where AAAA is 721 * the area passed down from mprotect_fixup, never extending beyond one 722 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 723 * 724 * AAAA AAAA AAAA AAAA 725 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 726 * cannot merge might become might become might become 727 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 728 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 729 * mremap move: PPPPNNNNNNNN 8 730 * AAAA 731 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 732 * might become case 1 below case 2 below case 3 below 733 * 734 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 735 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 736 */ 737struct vm_area_struct *vma_merge(struct mm_struct *mm, 738 struct vm_area_struct *prev, unsigned long addr, 739 unsigned long end, unsigned long vm_flags, 740 struct anon_vma *anon_vma, struct file *file, 741 pgoff_t pgoff, struct mempolicy *policy) 742{ 743 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 744 struct vm_area_struct *area, *next; 745 746 /* 747 * We later require that vma->vm_flags == vm_flags, 748 * so this tests vma->vm_flags & VM_SPECIAL, too. 749 */ 750 if (vm_flags & VM_SPECIAL) 751 return NULL; 752 753 if (prev) 754 next = prev->vm_next; 755 else 756 next = mm->mmap; 757 area = next; 758 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 759 next = next->vm_next; 760 761 /* 762 * Can it merge with the predecessor? 763 */ 764 if (prev && prev->vm_end == addr && 765 mpol_equal(vma_policy(prev), policy) && 766 can_vma_merge_after(prev, vm_flags, 767 anon_vma, file, pgoff)) { 768 /* 769 * OK, it can. Can we now merge in the successor as well? 770 */ 771 if (next && end == next->vm_start && 772 mpol_equal(policy, vma_policy(next)) && 773 can_vma_merge_before(next, vm_flags, 774 anon_vma, file, pgoff+pglen) && 775 is_mergeable_anon_vma(prev->anon_vma, 776 next->anon_vma)) { 777 /* cases 1, 6 */ 778 vma_adjust(prev, prev->vm_start, 779 next->vm_end, prev->vm_pgoff, NULL); 780 } else /* cases 2, 5, 7 */ 781 vma_adjust(prev, prev->vm_start, 782 end, prev->vm_pgoff, NULL); 783 return prev; 784 } 785 786 /* 787 * Can this new request be merged in front of next? 788 */ 789 if (next && end == next->vm_start && 790 mpol_equal(policy, vma_policy(next)) && 791 can_vma_merge_before(next, vm_flags, 792 anon_vma, file, pgoff+pglen)) { 793 if (prev && addr < prev->vm_end) /* case 4 */ 794 vma_adjust(prev, prev->vm_start, 795 addr, prev->vm_pgoff, NULL); 796 else /* cases 3, 8 */ 797 vma_adjust(area, addr, next->vm_end, 798 next->vm_pgoff - pglen, NULL); 799 return area; 800 } 801 802 return NULL; 803} 804 805/* 806 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 807 * neighbouring vmas for a suitable anon_vma, before it goes off 808 * to allocate a new anon_vma. It checks because a repetitive 809 * sequence of mprotects and faults may otherwise lead to distinct 810 * anon_vmas being allocated, preventing vma merge in subsequent 811 * mprotect. 812 */ 813struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 814{ 815 struct vm_area_struct *near; 816 unsigned long vm_flags; 817 818 near = vma->vm_next; 819 if (!near) 820 goto try_prev; 821 822 /* 823 * Since only mprotect tries to remerge vmas, match flags 824 * which might be mprotected into each other later on. 825 * Neither mlock nor madvise tries to remerge at present, 826 * so leave their flags as obstructing a merge. 827 */ 828 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 829 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 830 831 if (near->anon_vma && vma->vm_end == near->vm_start && 832 mpol_equal(vma_policy(vma), vma_policy(near)) && 833 can_vma_merge_before(near, vm_flags, 834 NULL, vma->vm_file, vma->vm_pgoff + 835 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 836 return near->anon_vma; 837try_prev: 838 /* 839 * It is potentially slow to have to call find_vma_prev here. 840 * But it's only on the first write fault on the vma, not 841 * every time, and we could devise a way to avoid it later 842 * (e.g. stash info in next's anon_vma_node when assigning 843 * an anon_vma, or when trying vma_merge). Another time. 844 */ 845 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 846 if (!near) 847 goto none; 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 && near->vm_end == vma->vm_start && 853 mpol_equal(vma_policy(near), vma_policy(vma)) && 854 can_vma_merge_after(near, vm_flags, 855 NULL, vma->vm_file, vma->vm_pgoff)) 856 return near->anon_vma; 857none: 858 /* 859 * There's no absolute need to look only at touching neighbours: 860 * we could search further afield for "compatible" anon_vmas. 861 * But it would probably just be a waste of time searching, 862 * or lead to too many vmas hanging off the same anon_vma. 863 * We're trying to allow mprotect remerging later on, 864 * not trying to minimize memory used for anon_vmas. 865 */ 866 return NULL; 867} 868 869#ifdef CONFIG_PROC_FS 870void vm_stat_account(struct mm_struct *mm, unsigned long flags, 871 struct file *file, long pages) 872{ 873 const unsigned long stack_flags 874 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 875 876 if (file) { 877 mm->shared_vm += pages; 878 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 879 mm->exec_vm += pages; 880 } else if (flags & stack_flags) 881 mm->stack_vm += pages; 882 if (flags & (VM_RESERVED|VM_IO)) 883 mm->reserved_vm += pages; 884} 885#endif /* CONFIG_PROC_FS */ 886 887/* 888 * The caller must hold down_write(current->mm->mmap_sem). 889 */ 890 891unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 892 unsigned long len, unsigned long prot, 893 unsigned long flags, unsigned long pgoff) 894{ 895 struct mm_struct * mm = current->mm; 896 struct inode *inode; 897 unsigned int vm_flags; 898 int error; 899 int accountable = 1; 900 unsigned long reqprot = prot; 901 902 /* 903 * Does the application expect PROT_READ to imply PROT_EXEC? 904 * 905 * (the exception is when the underlying filesystem is noexec 906 * mounted, in which case we dont add PROT_EXEC.) 907 */ 908 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 909 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 910 prot |= PROT_EXEC; 911 912 if (!len) 913 return -EINVAL; 914 915 if (!(flags & MAP_FIXED)) 916 addr = round_hint_to_min(addr); 917 918 error = arch_mmap_check(addr, len, flags); 919 if (error) 920 return error; 921 922 /* Careful about overflows.. */ 923 len = PAGE_ALIGN(len); 924 if (!len || len > TASK_SIZE) 925 return -ENOMEM; 926 927 /* offset overflow? */ 928 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 929 return -EOVERFLOW; 930 931 /* Too many mappings? */ 932 if (mm->map_count > sysctl_max_map_count) 933 return -ENOMEM; 934 935 /* Obtain the address to map to. we verify (or select) it and ensure 936 * that it represents a valid section of the address space. 937 */ 938 addr = get_unmapped_area(file, addr, len, pgoff, flags); 939 if (addr & ~PAGE_MASK) 940 return addr; 941 942 /* Do simple checking here so the lower-level routines won't have 943 * to. we assume access permissions have been handled by the open 944 * of the memory object, so we don't do any here. 945 */ 946 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 947 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 948 949 if (flags & MAP_LOCKED) { 950 if (!can_do_mlock()) 951 return -EPERM; 952 vm_flags |= VM_LOCKED; 953 } 954 /* mlock MCL_FUTURE? */ 955 if (vm_flags & VM_LOCKED) { 956 unsigned long locked, lock_limit; 957 locked = len >> PAGE_SHIFT; 958 locked += mm->locked_vm; 959 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 960 lock_limit >>= PAGE_SHIFT; 961 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 962 return -EAGAIN; 963 } 964 965 inode = file ? file->f_path.dentry->d_inode : NULL; 966 967 if (file) { 968 switch (flags & MAP_TYPE) { 969 case MAP_SHARED: 970 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 971 return -EACCES; 972 973 /* 974 * Make sure we don't allow writing to an append-only 975 * file.. 976 */ 977 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 978 return -EACCES; 979 980 /* 981 * Make sure there are no mandatory locks on the file. 982 */ 983 if (locks_verify_locked(inode)) 984 return -EAGAIN; 985 986 vm_flags |= VM_SHARED | VM_MAYSHARE; 987 if (!(file->f_mode & FMODE_WRITE)) 988 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 989 990 /* fall through */ 991 case MAP_PRIVATE: 992 if (!(file->f_mode & FMODE_READ)) 993 return -EACCES; 994 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 995 if (vm_flags & VM_EXEC) 996 return -EPERM; 997 vm_flags &= ~VM_MAYEXEC; 998 } 999 if (is_file_hugepages(file)) 1000 accountable = 0; 1001 1002 if (!file->f_op || !file->f_op->mmap) 1003 return -ENODEV; 1004 break; 1005 1006 default: 1007 return -EINVAL; 1008 } 1009 } else { 1010 switch (flags & MAP_TYPE) { 1011 case MAP_SHARED: 1012 vm_flags |= VM_SHARED | VM_MAYSHARE; 1013 break; 1014 case MAP_PRIVATE: 1015 /* 1016 * Set pgoff according to addr for anon_vma. 1017 */ 1018 pgoff = addr >> PAGE_SHIFT; 1019 break; 1020 default: 1021 return -EINVAL; 1022 } 1023 } 1024 1025 error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1026 if (error) 1027 return error; 1028 1029 return mmap_region(file, addr, len, flags, vm_flags, pgoff, 1030 accountable); 1031} 1032EXPORT_SYMBOL(do_mmap_pgoff); 1033 1034/* 1035 * Some shared mappigns will want the pages marked read-only 1036 * to track write events. If so, we'll downgrade vm_page_prot 1037 * to the private version (using protection_map[] without the 1038 * VM_SHARED bit). 1039 */ 1040int vma_wants_writenotify(struct vm_area_struct *vma) 1041{ 1042 unsigned int vm_flags = vma->vm_flags; 1043 1044 /* If it was private or non-writable, the write bit is already clear */ 1045 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1046 return 0; 1047 1048 /* The backer wishes to know when pages are first written to? */ 1049 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1050 return 1; 1051 1052 /* The open routine did something to the protections already? */ 1053 if (pgprot_val(vma->vm_page_prot) != 1054 pgprot_val(vm_get_page_prot(vm_flags))) 1055 return 0; 1056 1057 /* Specialty mapping? */ 1058 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) 1059 return 0; 1060 1061 /* Can the mapping track the dirty pages? */ 1062 return vma->vm_file && vma->vm_file->f_mapping && 1063 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1064} 1065 1066 1067unsigned long mmap_region(struct file *file, unsigned long addr, 1068 unsigned long len, unsigned long flags, 1069 unsigned int vm_flags, unsigned long pgoff, 1070 int accountable) 1071{ 1072 struct mm_struct *mm = current->mm; 1073 struct vm_area_struct *vma, *prev; 1074 int correct_wcount = 0; 1075 int error; 1076 struct rb_node **rb_link, *rb_parent; 1077 unsigned long charged = 0; 1078 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; 1079 1080 /* Clear old maps */ 1081 error = -ENOMEM; 1082munmap_back: 1083 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1084 if (vma && vma->vm_start < addr + len) { 1085 if (do_munmap(mm, addr, len)) 1086 return -ENOMEM; 1087 goto munmap_back; 1088 } 1089 1090 /* Check against address space limit. */ 1091 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1092 return -ENOMEM; 1093 1094 if (accountable && (!(flags & MAP_NORESERVE) || 1095 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { 1096 if (vm_flags & VM_SHARED) { 1097 /* Check memory availability in shmem_file_setup? */ 1098 vm_flags |= VM_ACCOUNT; 1099 } else if (vm_flags & VM_WRITE) { 1100 /* 1101 * Private writable mapping: check memory availability 1102 */ 1103 charged = len >> PAGE_SHIFT; 1104 if (security_vm_enough_memory(charged)) 1105 return -ENOMEM; 1106 vm_flags |= VM_ACCOUNT; 1107 } 1108 } 1109 1110 /* 1111 * Can we just expand an old private anonymous mapping? 1112 * The VM_SHARED test is necessary because shmem_zero_setup 1113 * will create the file object for a shared anonymous map below. 1114 */ 1115 if (!file && !(vm_flags & VM_SHARED) && 1116 vma_merge(mm, prev, addr, addr + len, vm_flags, 1117 NULL, NULL, pgoff, NULL)) 1118 goto out; 1119 1120 /* 1121 * Determine the object being mapped and call the appropriate 1122 * specific mapper. the address has already been validated, but 1123 * not unmapped, but the maps are removed from the list. 1124 */ 1125 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1126 if (!vma) { 1127 error = -ENOMEM; 1128 goto unacct_error; 1129 } 1130 1131 vma->vm_mm = mm; 1132 vma->vm_start = addr; 1133 vma->vm_end = addr + len; 1134 vma->vm_flags = vm_flags; 1135 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1136 vma->vm_pgoff = pgoff; 1137 1138 if (file) { 1139 error = -EINVAL; 1140 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1141 goto free_vma; 1142 if (vm_flags & VM_DENYWRITE) { 1143 error = deny_write_access(file); 1144 if (error) 1145 goto free_vma; 1146 correct_wcount = 1; 1147 } 1148 vma->vm_file = file; 1149 get_file(file); 1150 error = file->f_op->mmap(file, vma); 1151 if (error) 1152 goto unmap_and_free_vma; 1153 } else if (vm_flags & VM_SHARED) { 1154 error = shmem_zero_setup(vma); 1155 if (error) 1156 goto free_vma; 1157 } 1158 1159 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1160 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1161 * that memory reservation must be checked; but that reservation 1162 * belongs to shared memory object, not to vma: so now clear it. 1163 */ 1164 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1165 vma->vm_flags &= ~VM_ACCOUNT; 1166 1167 /* Can addr have changed?? 1168 * 1169 * Answer: Yes, several device drivers can do it in their 1170 * f_op->mmap method. -DaveM 1171 */ 1172 addr = vma->vm_start; 1173 pgoff = vma->vm_pgoff; 1174 vm_flags = vma->vm_flags; 1175 1176 if (vma_wants_writenotify(vma)) 1177 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); 1178 1179 if (!file || !vma_merge(mm, prev, addr, vma->vm_end, 1180 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1181 file = vma->vm_file; 1182 vma_link(mm, vma, prev, rb_link, rb_parent); 1183 if (correct_wcount) 1184 atomic_inc(&inode->i_writecount); 1185 } else { 1186 if (file) { 1187 if (correct_wcount) 1188 atomic_inc(&inode->i_writecount); 1189 fput(file); 1190 } 1191 mpol_free(vma_policy(vma)); 1192 kmem_cache_free(vm_area_cachep, vma); 1193 } 1194out: 1195 mm->total_vm += len >> PAGE_SHIFT; 1196 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1197 if (vm_flags & VM_LOCKED) { 1198 mm->locked_vm += len >> PAGE_SHIFT; 1199 make_pages_present(addr, addr + len); 1200 } 1201 if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) 1202 make_pages_present(addr, addr + len); 1203 return addr; 1204 1205unmap_and_free_vma: 1206 if (correct_wcount) 1207 atomic_inc(&inode->i_writecount); 1208 vma->vm_file = NULL; 1209 fput(file); 1210 1211 /* Undo any partial mapping done by a device driver. */ 1212 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1213 charged = 0; 1214free_vma: 1215 kmem_cache_free(vm_area_cachep, vma); 1216unacct_error: 1217 if (charged) 1218 vm_unacct_memory(charged); 1219 return error; 1220} 1221 1222/* Get an address range which is currently unmapped. 1223 * For shmat() with addr=0. 1224 * 1225 * Ugly calling convention alert: 1226 * Return value with the low bits set means error value, 1227 * ie 1228 * if (ret & ~PAGE_MASK) 1229 * error = ret; 1230 * 1231 * This function "knows" that -ENOMEM has the bits set. 1232 */ 1233#ifndef HAVE_ARCH_UNMAPPED_AREA 1234unsigned long 1235arch_get_unmapped_area(struct file *filp, unsigned long addr, 1236 unsigned long len, unsigned long pgoff, unsigned long flags) 1237{ 1238 struct mm_struct *mm = current->mm; 1239 struct vm_area_struct *vma; 1240 unsigned long start_addr; 1241 1242 if (len > TASK_SIZE) 1243 return -ENOMEM; 1244 1245 if (flags & MAP_FIXED) 1246 return addr; 1247 1248 if (addr) { 1249 addr = PAGE_ALIGN(addr); 1250 vma = find_vma(mm, addr); 1251 if (TASK_SIZE - len >= addr && 1252 (!vma || addr + len <= vma->vm_start)) 1253 return addr; 1254 } 1255 if (len > mm->cached_hole_size) { 1256 start_addr = addr = mm->free_area_cache; 1257 } else { 1258 start_addr = addr = TASK_UNMAPPED_BASE; 1259 mm->cached_hole_size = 0; 1260 } 1261 1262full_search: 1263 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1264 /* At this point: (!vma || addr < vma->vm_end). */ 1265 if (TASK_SIZE - len < addr) { 1266 /* 1267 * Start a new search - just in case we missed 1268 * some holes. 1269 */ 1270 if (start_addr != TASK_UNMAPPED_BASE) { 1271 addr = TASK_UNMAPPED_BASE; 1272 start_addr = addr; 1273 mm->cached_hole_size = 0; 1274 goto full_search; 1275 } 1276 return -ENOMEM; 1277 } 1278 if (!vma || addr + len <= vma->vm_start) { 1279 /* 1280 * Remember the place where we stopped the search: 1281 */ 1282 mm->free_area_cache = addr + len; 1283 return addr; 1284 } 1285 if (addr + mm->cached_hole_size < vma->vm_start) 1286 mm->cached_hole_size = vma->vm_start - addr; 1287 addr = vma->vm_end; 1288 } 1289} 1290#endif 1291 1292void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1293{ 1294 /* 1295 * Is this a new hole at the lowest possible address? 1296 */ 1297 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1298 mm->free_area_cache = addr; 1299 mm->cached_hole_size = ~0UL; 1300 } 1301} 1302 1303/* 1304 * This mmap-allocator allocates new areas top-down from below the 1305 * stack's low limit (the base): 1306 */ 1307#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1308unsigned long 1309arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1310 const unsigned long len, const unsigned long pgoff, 1311 const unsigned long flags) 1312{ 1313 struct vm_area_struct *vma; 1314 struct mm_struct *mm = current->mm; 1315 unsigned long addr = addr0; 1316 1317 /* requested length too big for entire address space */ 1318 if (len > TASK_SIZE) 1319 return -ENOMEM; 1320 1321 if (flags & MAP_FIXED) 1322 return addr; 1323 1324 /* requesting a specific address */ 1325 if (addr) { 1326 addr = PAGE_ALIGN(addr); 1327 vma = find_vma(mm, addr); 1328 if (TASK_SIZE - len >= addr && 1329 (!vma || addr + len <= vma->vm_start)) 1330 return addr; 1331 } 1332 1333 /* check if free_area_cache is useful for us */ 1334 if (len <= mm->cached_hole_size) { 1335 mm->cached_hole_size = 0; 1336 mm->free_area_cache = mm->mmap_base; 1337 } 1338 1339 /* either no address requested or can't fit in requested address hole */ 1340 addr = mm->free_area_cache; 1341 1342 /* make sure it can fit in the remaining address space */ 1343 if (addr > len) { 1344 vma = find_vma(mm, addr-len); 1345 if (!vma || addr <= vma->vm_start) 1346 /* remember the address as a hint for next time */ 1347 return (mm->free_area_cache = addr-len); 1348 } 1349 1350 if (mm->mmap_base < len) 1351 goto bottomup; 1352 1353 addr = mm->mmap_base-len; 1354 1355 do { 1356 /* 1357 * Lookup failure means no vma is above this address, 1358 * else if new region fits below vma->vm_start, 1359 * return with success: 1360 */ 1361 vma = find_vma(mm, addr); 1362 if (!vma || addr+len <= vma->vm_start) 1363 /* remember the address as a hint for next time */ 1364 return (mm->free_area_cache = addr); 1365 1366 /* remember the largest hole we saw so far */ 1367 if (addr + mm->cached_hole_size < vma->vm_start) 1368 mm->cached_hole_size = vma->vm_start - addr; 1369 1370 /* try just below the current vma->vm_start */ 1371 addr = vma->vm_start-len; 1372 } while (len < vma->vm_start); 1373 1374bottomup: 1375 /* 1376 * A failed mmap() very likely causes application failure, 1377 * so fall back to the bottom-up function here. This scenario 1378 * can happen with large stack limits and large mmap() 1379 * allocations. 1380 */ 1381 mm->cached_hole_size = ~0UL; 1382 mm->free_area_cache = TASK_UNMAPPED_BASE; 1383 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1384 /* 1385 * Restore the topdown base: 1386 */ 1387 mm->free_area_cache = mm->mmap_base; 1388 mm->cached_hole_size = ~0UL; 1389 1390 return addr; 1391} 1392#endif 1393 1394void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1395{ 1396 /* 1397 * Is this a new hole at the highest possible address? 1398 */ 1399 if (addr > mm->free_area_cache) 1400 mm->free_area_cache = addr; 1401 1402 /* dont allow allocations above current base */ 1403 if (mm->free_area_cache > mm->mmap_base) 1404 mm->free_area_cache = mm->mmap_base; 1405} 1406 1407unsigned long 1408get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1409 unsigned long pgoff, unsigned long flags) 1410{ 1411 unsigned long (*get_area)(struct file *, unsigned long, 1412 unsigned long, unsigned long, unsigned long); 1413 1414 get_area = current->mm->get_unmapped_area; 1415 if (file && file->f_op && file->f_op->get_unmapped_area) 1416 get_area = file->f_op->get_unmapped_area; 1417 addr = get_area(file, addr, len, pgoff, flags); 1418 if (IS_ERR_VALUE(addr)) 1419 return addr; 1420 1421 if (addr > TASK_SIZE - len) 1422 return -ENOMEM; 1423 if (addr & ~PAGE_MASK) 1424 return -EINVAL; 1425 1426 return addr; 1427} 1428 1429EXPORT_SYMBOL(get_unmapped_area); 1430 1431/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1432struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1433{ 1434 struct vm_area_struct *vma = NULL; 1435 1436 if (mm) { 1437 /* Check the cache first. */ 1438 /* (Cache hit rate is typically around 35%.) */ 1439 vma = mm->mmap_cache; 1440 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1441 struct rb_node * rb_node; 1442 1443 rb_node = mm->mm_rb.rb_node; 1444 vma = NULL; 1445 1446 while (rb_node) { 1447 struct vm_area_struct * vma_tmp; 1448 1449 vma_tmp = rb_entry(rb_node, 1450 struct vm_area_struct, vm_rb); 1451 1452 if (vma_tmp->vm_end > addr) { 1453 vma = vma_tmp; 1454 if (vma_tmp->vm_start <= addr) 1455 break; 1456 rb_node = rb_node->rb_left; 1457 } else 1458 rb_node = rb_node->rb_right; 1459 } 1460 if (vma) 1461 mm->mmap_cache = vma; 1462 } 1463 } 1464 return vma; 1465} 1466 1467EXPORT_SYMBOL(find_vma); 1468 1469/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1470struct vm_area_struct * 1471find_vma_prev(struct mm_struct *mm, unsigned long addr, 1472 struct vm_area_struct **pprev) 1473{ 1474 struct vm_area_struct *vma = NULL, *prev = NULL; 1475 struct rb_node * rb_node; 1476 if (!mm) 1477 goto out; 1478 1479 /* Guard against addr being lower than the first VMA */ 1480 vma = mm->mmap; 1481 1482 /* Go through the RB tree quickly. */ 1483 rb_node = mm->mm_rb.rb_node; 1484 1485 while (rb_node) { 1486 struct vm_area_struct *vma_tmp; 1487 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1488 1489 if (addr < vma_tmp->vm_end) { 1490 rb_node = rb_node->rb_left; 1491 } else { 1492 prev = vma_tmp; 1493 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1494 break; 1495 rb_node = rb_node->rb_right; 1496 } 1497 } 1498 1499out: 1500 *pprev = prev; 1501 return prev ? prev->vm_next : vma; 1502} 1503 1504/* 1505 * Verify that the stack growth is acceptable and 1506 * update accounting. This is shared with both the 1507 * grow-up and grow-down cases. 1508 */ 1509static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1510{ 1511 struct mm_struct *mm = vma->vm_mm; 1512 struct rlimit *rlim = current->signal->rlim; 1513 unsigned long new_start; 1514 1515 /* address space limit tests */ 1516 if (!may_expand_vm(mm, grow)) 1517 return -ENOMEM; 1518 1519 /* Stack limit test */ 1520 if (size > rlim[RLIMIT_STACK].rlim_cur) 1521 return -ENOMEM; 1522 1523 /* mlock limit tests */ 1524 if (vma->vm_flags & VM_LOCKED) { 1525 unsigned long locked; 1526 unsigned long limit; 1527 locked = mm->locked_vm + grow; 1528 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1529 if (locked > limit && !capable(CAP_IPC_LOCK)) 1530 return -ENOMEM; 1531 } 1532 1533 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1534 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1535 vma->vm_end - size; 1536 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1537 return -EFAULT; 1538 1539 /* 1540 * Overcommit.. This must be the final test, as it will 1541 * update security statistics. 1542 */ 1543 if (security_vm_enough_memory(grow)) 1544 return -ENOMEM; 1545 1546 /* Ok, everything looks good - let it rip */ 1547 mm->total_vm += grow; 1548 if (vma->vm_flags & VM_LOCKED) 1549 mm->locked_vm += grow; 1550 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1551 return 0; 1552} 1553 1554#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1555/* 1556 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1557 * vma is the last one with address > vma->vm_end. Have to extend vma. 1558 */ 1559#ifndef CONFIG_IA64 1560static inline 1561#endif 1562int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1563{ 1564 int error; 1565 1566 if (!(vma->vm_flags & VM_GROWSUP)) 1567 return -EFAULT; 1568 1569 /* 1570 * We must make sure the anon_vma is allocated 1571 * so that the anon_vma locking is not a noop. 1572 */ 1573 if (unlikely(anon_vma_prepare(vma))) 1574 return -ENOMEM; 1575 anon_vma_lock(vma); 1576 1577 /* 1578 * vma->vm_start/vm_end cannot change under us because the caller 1579 * is required to hold the mmap_sem in read mode. We need the 1580 * anon_vma lock to serialize against concurrent expand_stacks. 1581 * Also guard against wrapping around to address 0. 1582 */ 1583 if (address < PAGE_ALIGN(address+4)) 1584 address = PAGE_ALIGN(address+4); 1585 else { 1586 anon_vma_unlock(vma); 1587 return -ENOMEM; 1588 } 1589 error = 0; 1590 1591 /* Somebody else might have raced and expanded it already */ 1592 if (address > vma->vm_end) { 1593 unsigned long size, grow; 1594 1595 size = address - vma->vm_start; 1596 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1597 1598 error = acct_stack_growth(vma, size, grow); 1599 if (!error) 1600 vma->vm_end = address; 1601 } 1602 anon_vma_unlock(vma); 1603 return error; 1604} 1605#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1606 1607/* 1608 * vma is the first one with address < vma->vm_start. Have to extend vma. 1609 */ 1610static inline int expand_downwards(struct vm_area_struct *vma, 1611 unsigned long address) 1612{ 1613 int error; 1614 1615 /* 1616 * We must make sure the anon_vma is allocated 1617 * so that the anon_vma locking is not a noop. 1618 */ 1619 if (unlikely(anon_vma_prepare(vma))) 1620 return -ENOMEM; 1621 1622 address &= PAGE_MASK; 1623 error = security_file_mmap(0, 0, 0, 0, address, 1); 1624 if (error) 1625 return error; 1626 1627 anon_vma_lock(vma); 1628 1629 /* 1630 * vma->vm_start/vm_end cannot change under us because the caller 1631 * is required to hold the mmap_sem in read mode. We need the 1632 * anon_vma lock to serialize against concurrent expand_stacks. 1633 */ 1634 1635 /* Somebody else might have raced and expanded it already */ 1636 if (address < vma->vm_start) { 1637 unsigned long size, grow; 1638 1639 size = vma->vm_end - address; 1640 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1641 1642 error = acct_stack_growth(vma, size, grow); 1643 if (!error) { 1644 vma->vm_start = address; 1645 vma->vm_pgoff -= grow; 1646 } 1647 } 1648 anon_vma_unlock(vma); 1649 return error; 1650} 1651 1652int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) 1653{ 1654 return expand_downwards(vma, address); 1655} 1656 1657#ifdef CONFIG_STACK_GROWSUP 1658int expand_stack(struct vm_area_struct *vma, unsigned long address) 1659{ 1660 return expand_upwards(vma, address); 1661} 1662 1663struct vm_area_struct * 1664find_extend_vma(struct mm_struct *mm, unsigned long addr) 1665{ 1666 struct vm_area_struct *vma, *prev; 1667 1668 addr &= PAGE_MASK; 1669 vma = find_vma_prev(mm, addr, &prev); 1670 if (vma && (vma->vm_start <= addr)) 1671 return vma; 1672 if (!prev || expand_stack(prev, addr)) 1673 return NULL; 1674 if (prev->vm_flags & VM_LOCKED) 1675 make_pages_present(addr, prev->vm_end); 1676 return prev; 1677} 1678#else 1679int expand_stack(struct vm_area_struct *vma, unsigned long address) 1680{ 1681 return expand_downwards(vma, address); 1682} 1683 1684struct vm_area_struct * 1685find_extend_vma(struct mm_struct * mm, unsigned long addr) 1686{ 1687 struct vm_area_struct * vma; 1688 unsigned long start; 1689 1690 addr &= PAGE_MASK; 1691 vma = find_vma(mm,addr); 1692 if (!vma) 1693 return NULL; 1694 if (vma->vm_start <= addr) 1695 return vma; 1696 if (!(vma->vm_flags & VM_GROWSDOWN)) 1697 return NULL; 1698 start = vma->vm_start; 1699 if (expand_stack(vma, addr)) 1700 return NULL; 1701 if (vma->vm_flags & VM_LOCKED) 1702 make_pages_present(addr, start); 1703 return vma; 1704} 1705#endif 1706 1707/* 1708 * Ok - we have the memory areas we should free on the vma list, 1709 * so release them, and do the vma updates. 1710 * 1711 * Called with the mm semaphore held. 1712 */ 1713static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1714{ 1715 /* Update high watermark before we lower total_vm */ 1716 update_hiwater_vm(mm); 1717 do { 1718 long nrpages = vma_pages(vma); 1719 1720 mm->total_vm -= nrpages; 1721 if (vma->vm_flags & VM_LOCKED) 1722 mm->locked_vm -= nrpages; 1723 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1724 vma = remove_vma(vma); 1725 } while (vma); 1726 validate_mm(mm); 1727} 1728 1729/* 1730 * Get rid of page table information in the indicated region. 1731 * 1732 * Called with the mm semaphore held. 1733 */ 1734static void unmap_region(struct mm_struct *mm, 1735 struct vm_area_struct *vma, struct vm_area_struct *prev, 1736 unsigned long start, unsigned long end) 1737{ 1738 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1739 struct mmu_gather *tlb; 1740 unsigned long nr_accounted = 0; 1741 1742 lru_add_drain(); 1743 tlb = tlb_gather_mmu(mm, 0); 1744 update_hiwater_rss(mm); 1745 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1746 vm_unacct_memory(nr_accounted); 1747 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1748 next? next->vm_start: 0); 1749 tlb_finish_mmu(tlb, start, end); 1750} 1751 1752/* 1753 * Create a list of vma's touched by the unmap, removing them from the mm's 1754 * vma list as we go.. 1755 */ 1756static void 1757detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1758 struct vm_area_struct *prev, unsigned long end) 1759{ 1760 struct vm_area_struct **insertion_point; 1761 struct vm_area_struct *tail_vma = NULL; 1762 unsigned long addr; 1763 1764 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1765 do { 1766 rb_erase(&vma->vm_rb, &mm->mm_rb); 1767 mm->map_count--; 1768 tail_vma = vma; 1769 vma = vma->vm_next; 1770 } while (vma && vma->vm_start < end); 1771 *insertion_point = vma; 1772 tail_vma->vm_next = NULL; 1773 if (mm->unmap_area == arch_unmap_area) 1774 addr = prev ? prev->vm_end : mm->mmap_base; 1775 else 1776 addr = vma ? vma->vm_start : mm->mmap_base; 1777 mm->unmap_area(mm, addr); 1778 mm->mmap_cache = NULL; /* Kill the cache. */ 1779} 1780 1781/* 1782 * Split a vma into two pieces at address 'addr', a new vma is allocated 1783 * either for the first part or the tail. 1784 */ 1785int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1786 unsigned long addr, int new_below) 1787{ 1788 struct mempolicy *pol; 1789 struct vm_area_struct *new; 1790 1791 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK)) 1792 return -EINVAL; 1793 1794 if (mm->map_count >= sysctl_max_map_count) 1795 return -ENOMEM; 1796 1797 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1798 if (!new) 1799 return -ENOMEM; 1800 1801 /* most fields are the same, copy all, and then fixup */ 1802 *new = *vma; 1803 1804 if (new_below) 1805 new->vm_end = addr; 1806 else { 1807 new->vm_start = addr; 1808 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1809 } 1810 1811 pol = mpol_copy(vma_policy(vma)); 1812 if (IS_ERR(pol)) { 1813 kmem_cache_free(vm_area_cachep, new); 1814 return PTR_ERR(pol); 1815 } 1816 vma_set_policy(new, pol); 1817 1818 if (new->vm_file) 1819 get_file(new->vm_file); 1820 1821 if (new->vm_ops && new->vm_ops->open) 1822 new->vm_ops->open(new); 1823 1824 if (new_below) 1825 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1826 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1827 else 1828 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1829 1830 return 0; 1831} 1832 1833/* Munmap is split into 2 main parts -- this part which finds 1834 * what needs doing, and the areas themselves, which do the 1835 * work. This now handles partial unmappings. 1836 * Jeremy Fitzhardinge <jeremy@goop.org> 1837 */ 1838int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1839{ 1840 unsigned long end; 1841 struct vm_area_struct *vma, *prev, *last; 1842 1843 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1844 return -EINVAL; 1845 1846 if ((len = PAGE_ALIGN(len)) == 0) 1847 return -EINVAL; 1848 1849 /* Find the first overlapping VMA */ 1850 vma = find_vma_prev(mm, start, &prev); 1851 if (!vma) 1852 return 0; 1853 /* we have start < vma->vm_end */ 1854 1855 /* if it doesn't overlap, we have nothing.. */ 1856 end = start + len; 1857 if (vma->vm_start >= end) 1858 return 0; 1859 1860 /* 1861 * If we need to split any vma, do it now to save pain later. 1862 * 1863 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1864 * unmapped vm_area_struct will remain in use: so lower split_vma 1865 * places tmp vma above, and higher split_vma places tmp vma below. 1866 */ 1867 if (start > vma->vm_start) { 1868 int error = split_vma(mm, vma, start, 0); 1869 if (error) 1870 return error; 1871 prev = vma; 1872 } 1873 1874 /* Does it split the last one? */ 1875 last = find_vma(mm, end); 1876 if (last && end > last->vm_start) { 1877 int error = split_vma(mm, last, end, 1); 1878 if (error) 1879 return error; 1880 } 1881 vma = prev? prev->vm_next: mm->mmap; 1882 1883 /* 1884 * Remove the vma's, and unmap the actual pages 1885 */ 1886 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1887 unmap_region(mm, vma, prev, start, end); 1888 1889 /* Fix up all other VM information */ 1890 remove_vma_list(mm, vma); 1891 1892 return 0; 1893} 1894 1895EXPORT_SYMBOL(do_munmap); 1896 1897asmlinkage long sys_munmap(unsigned long addr, size_t len) 1898{ 1899 int ret; 1900 struct mm_struct *mm = current->mm; 1901 1902 profile_munmap(addr); 1903 1904 down_write(&mm->mmap_sem); 1905 ret = do_munmap(mm, addr, len); 1906 up_write(&mm->mmap_sem); 1907 return ret; 1908} 1909 1910static inline void verify_mm_writelocked(struct mm_struct *mm) 1911{ 1912#ifdef CONFIG_DEBUG_VM 1913 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1914 WARN_ON(1); 1915 up_read(&mm->mmap_sem); 1916 } 1917#endif 1918} 1919 1920/* 1921 * this is really a simplified "do_mmap". it only handles 1922 * anonymous maps. eventually we may be able to do some 1923 * brk-specific accounting here. 1924 */ 1925unsigned long do_brk(unsigned long addr, unsigned long len) 1926{ 1927 struct mm_struct * mm = current->mm; 1928 struct vm_area_struct * vma, * prev; 1929 unsigned long flags; 1930 struct rb_node ** rb_link, * rb_parent; 1931 pgoff_t pgoff = addr >> PAGE_SHIFT; 1932 int error; 1933 1934 len = PAGE_ALIGN(len); 1935 if (!len) 1936 return addr; 1937 1938 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1939 return -EINVAL; 1940 1941 if (is_hugepage_only_range(mm, addr, len)) 1942 return -EINVAL; 1943 1944 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1945 1946 error = arch_mmap_check(addr, len, flags); 1947 if (error) 1948 return error; 1949 1950 /* 1951 * mlock MCL_FUTURE? 1952 */ 1953 if (mm->def_flags & VM_LOCKED) { 1954 unsigned long locked, lock_limit; 1955 locked = len >> PAGE_SHIFT; 1956 locked += mm->locked_vm; 1957 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1958 lock_limit >>= PAGE_SHIFT; 1959 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1960 return -EAGAIN; 1961 } 1962 1963 /* 1964 * mm->mmap_sem is required to protect against another thread 1965 * changing the mappings in case we sleep. 1966 */ 1967 verify_mm_writelocked(mm); 1968 1969 /* 1970 * Clear old maps. this also does some error checking for us 1971 */ 1972 munmap_back: 1973 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1974 if (vma && vma->vm_start < addr + len) { 1975 if (do_munmap(mm, addr, len)) 1976 return -ENOMEM; 1977 goto munmap_back; 1978 } 1979 1980 /* Check against address space limits *after* clearing old maps... */ 1981 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1982 return -ENOMEM; 1983 1984 if (mm->map_count > sysctl_max_map_count) 1985 return -ENOMEM; 1986 1987 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 1988 return -ENOMEM; 1989 1990 /* Can we just expand an old private anonymous mapping? */ 1991 if (vma_merge(mm, prev, addr, addr + len, flags, 1992 NULL, NULL, pgoff, NULL)) 1993 goto out; 1994 1995 /* 1996 * create a vma struct for an anonymous mapping 1997 */ 1998 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1999 if (!vma) { 2000 vm_unacct_memory(len >> PAGE_SHIFT); 2001 return -ENOMEM; 2002 } 2003 2004 vma->vm_mm = mm; 2005 vma->vm_start = addr; 2006 vma->vm_end = addr + len; 2007 vma->vm_pgoff = pgoff; 2008 vma->vm_flags = flags; 2009 vma->vm_page_prot = vm_get_page_prot(flags); 2010 vma_link(mm, vma, prev, rb_link, rb_parent); 2011out: 2012 mm->total_vm += len >> PAGE_SHIFT; 2013 if (flags & VM_LOCKED) { 2014 mm->locked_vm += len >> PAGE_SHIFT; 2015 make_pages_present(addr, addr + len); 2016 } 2017 return addr; 2018} 2019 2020EXPORT_SYMBOL(do_brk); 2021 2022/* Release all mmaps. */ 2023void exit_mmap(struct mm_struct *mm) 2024{ 2025 struct mmu_gather *tlb; 2026 struct vm_area_struct *vma = mm->mmap; 2027 unsigned long nr_accounted = 0; 2028 unsigned long end; 2029 2030 /* mm's last user has gone, and its about to be pulled down */ 2031 arch_exit_mmap(mm); 2032 2033 lru_add_drain(); 2034 flush_cache_mm(mm); 2035 tlb = tlb_gather_mmu(mm, 1); 2036 /* Don't update_hiwater_rss(mm) here, do_exit already did */ 2037 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2038 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 2039 vm_unacct_memory(nr_accounted); 2040 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); 2041 tlb_finish_mmu(tlb, 0, end); 2042 2043 /* 2044 * Walk the list again, actually closing and freeing it, 2045 * with preemption enabled, without holding any MM locks. 2046 */ 2047 while (vma) 2048 vma = remove_vma(vma); 2049 2050 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2051} 2052 2053/* Insert vm structure into process list sorted by address 2054 * and into the inode's i_mmap tree. If vm_file is non-NULL 2055 * then i_mmap_lock is taken here. 2056 */ 2057int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 2058{ 2059 struct vm_area_struct * __vma, * prev; 2060 struct rb_node ** rb_link, * rb_parent; 2061 2062 /* 2063 * The vm_pgoff of a purely anonymous vma should be irrelevant 2064 * until its first write fault, when page's anon_vma and index 2065 * are set. But now set the vm_pgoff it will almost certainly 2066 * end up with (unless mremap moves it elsewhere before that 2067 * first wfault), so /proc/pid/maps tells a consistent story. 2068 * 2069 * By setting it to reflect the virtual start address of the 2070 * vma, merges and splits can happen in a seamless way, just 2071 * using the existing file pgoff checks and manipulations. 2072 * Similarly in do_mmap_pgoff and in do_brk. 2073 */ 2074 if (!vma->vm_file) { 2075 BUG_ON(vma->anon_vma); 2076 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2077 } 2078 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2079 if (__vma && __vma->vm_start < vma->vm_end) 2080 return -ENOMEM; 2081 if ((vma->vm_flags & VM_ACCOUNT) && 2082 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2083 return -ENOMEM; 2084 vma_link(mm, vma, prev, rb_link, rb_parent); 2085 return 0; 2086} 2087 2088/* 2089 * Copy the vma structure to a new location in the same mm, 2090 * prior to moving page table entries, to effect an mremap move. 2091 */ 2092struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2093 unsigned long addr, unsigned long len, pgoff_t pgoff) 2094{ 2095 struct vm_area_struct *vma = *vmap; 2096 unsigned long vma_start = vma->vm_start; 2097 struct mm_struct *mm = vma->vm_mm; 2098 struct vm_area_struct *new_vma, *prev; 2099 struct rb_node **rb_link, *rb_parent; 2100 struct mempolicy *pol; 2101 2102 /* 2103 * If anonymous vma has not yet been faulted, update new pgoff 2104 * to match new location, to increase its chance of merging. 2105 */ 2106 if (!vma->vm_file && !vma->anon_vma) 2107 pgoff = addr >> PAGE_SHIFT; 2108 2109 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2110 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2111 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2112 if (new_vma) { 2113 /* 2114 * Source vma may have been merged into new_vma 2115 */ 2116 if (vma_start >= new_vma->vm_start && 2117 vma_start < new_vma->vm_end) 2118 *vmap = new_vma; 2119 } else { 2120 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2121 if (new_vma) { 2122 *new_vma = *vma; 2123 pol = mpol_copy(vma_policy(vma)); 2124 if (IS_ERR(pol)) { 2125 kmem_cache_free(vm_area_cachep, new_vma); 2126 return NULL; 2127 } 2128 vma_set_policy(new_vma, pol); 2129 new_vma->vm_start = addr; 2130 new_vma->vm_end = addr + len; 2131 new_vma->vm_pgoff = pgoff; 2132 if (new_vma->vm_file) 2133 get_file(new_vma->vm_file); 2134 if (new_vma->vm_ops && new_vma->vm_ops->open) 2135 new_vma->vm_ops->open(new_vma); 2136 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2137 } 2138 } 2139 return new_vma; 2140} 2141 2142/* 2143 * Return true if the calling process may expand its vm space by the passed 2144 * number of pages 2145 */ 2146int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2147{ 2148 unsigned long cur = mm->total_vm; /* pages */ 2149 unsigned long lim; 2150 2151 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2152 2153 if (cur + npages > lim) 2154 return 0; 2155 return 1; 2156} 2157 2158 2159static struct page *special_mapping_nopage(struct vm_area_struct *vma, 2160 unsigned long address, int *type) 2161{ 2162 struct page **pages; 2163 2164 BUG_ON(address < vma->vm_start || address >= vma->vm_end); 2165 2166 address -= vma->vm_start; 2167 for (pages = vma->vm_private_data; address > 0 && *pages; ++pages) 2168 address -= PAGE_SIZE; 2169 2170 if (*pages) { 2171 struct page *page = *pages; 2172 get_page(page); 2173 return page; 2174 } 2175 2176 return NOPAGE_SIGBUS; 2177} 2178 2179/* 2180 * Having a close hook prevents vma merging regardless of flags. 2181 */ 2182static void special_mapping_close(struct vm_area_struct *vma) 2183{ 2184} 2185 2186static struct vm_operations_struct special_mapping_vmops = { 2187 .close = special_mapping_close, 2188 .nopage = special_mapping_nopage, 2189}; 2190 2191/* 2192 * Called with mm->mmap_sem held for writing. 2193 * Insert a new vma covering the given region, with the given flags. 2194 * Its pages are supplied by the given array of struct page *. 2195 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2196 * The region past the last page supplied will always produce SIGBUS. 2197 * The array pointer and the pages it points to are assumed to stay alive 2198 * for as long as this mapping might exist. 2199 */ 2200int install_special_mapping(struct mm_struct *mm, 2201 unsigned long addr, unsigned long len, 2202 unsigned long vm_flags, struct page **pages) 2203{ 2204 struct vm_area_struct *vma; 2205 2206 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2207 if (unlikely(vma == NULL)) 2208 return -ENOMEM; 2209 2210 vma->vm_mm = mm; 2211 vma->vm_start = addr; 2212 vma->vm_end = addr + len; 2213 2214 vma->vm_flags = vm_flags | mm->def_flags; 2215 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 2216 2217 vma->vm_ops = &special_mapping_vmops; 2218 vma->vm_private_data = pages; 2219 2220 if (unlikely(insert_vm_struct(mm, vma))) { 2221 kmem_cache_free(vm_area_cachep, vma); 2222 return -ENOMEM; 2223 } 2224 2225 mm->total_vm += len >> PAGE_SHIFT; 2226 2227 return 0; 2228} 2229