mmap.c revision cdfd4325c0d878679bd6a3ba8285b71d9980e3c0
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#include "internal.h" 36 37#ifndef arch_mmap_check 38#define arch_mmap_check(addr, len, flags) (0) 39#endif 40 41#ifndef arch_rebalance_pgtables 42#define arch_rebalance_pgtables(addr, len) (addr) 43#endif 44 45static void unmap_region(struct mm_struct *mm, 46 struct vm_area_struct *vma, struct vm_area_struct *prev, 47 unsigned long start, unsigned long end); 48 49/* 50 * WARNING: the debugging will use recursive algorithms so never enable this 51 * unless you know what you are doing. 52 */ 53#undef DEBUG_MM_RB 54 55/* description of effects of mapping type and prot in current implementation. 56 * this is due to the limited x86 page protection hardware. The expected 57 * behavior is in parens: 58 * 59 * map_type prot 60 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 61 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 62 * w: (no) no w: (no) no w: (yes) yes w: (no) no 63 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 64 * 65 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 66 * w: (no) no w: (no) no w: (copy) copy w: (no) no 67 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 68 * 69 */ 70pgprot_t protection_map[16] = { 71 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 72 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 73}; 74 75pgprot_t vm_get_page_prot(unsigned long vm_flags) 76{ 77 return __pgprot(pgprot_val(protection_map[vm_flags & 78 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | 79 pgprot_val(arch_vm_get_page_prot(vm_flags))); 80} 81EXPORT_SYMBOL(vm_get_page_prot); 82 83int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 84int sysctl_overcommit_ratio = 50; /* default is 50% */ 85int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 86atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0); 87 88/* 89 * Check that a process has enough memory to allocate a new virtual 90 * mapping. 0 means there is enough memory for the allocation to 91 * succeed and -ENOMEM implies there is not. 92 * 93 * We currently support three overcommit policies, which are set via the 94 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 95 * 96 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 97 * Additional code 2002 Jul 20 by Robert Love. 98 * 99 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 100 * 101 * Note this is a helper function intended to be used by LSMs which 102 * wish to use this logic. 103 */ 104int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 105{ 106 unsigned long free, allowed; 107 108 vm_acct_memory(pages); 109 110 /* 111 * Sometimes we want to use more memory than we have 112 */ 113 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 114 return 0; 115 116 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 117 unsigned long n; 118 119 free = global_page_state(NR_FILE_PAGES); 120 free += nr_swap_pages; 121 122 /* 123 * Any slabs which are created with the 124 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 125 * which are reclaimable, under pressure. The dentry 126 * cache and most inode caches should fall into this 127 */ 128 free += global_page_state(NR_SLAB_RECLAIMABLE); 129 130 /* 131 * Leave the last 3% for root 132 */ 133 if (!cap_sys_admin) 134 free -= free / 32; 135 136 if (free > pages) 137 return 0; 138 139 /* 140 * nr_free_pages() is very expensive on large systems, 141 * only call if we're about to fail. 142 */ 143 n = nr_free_pages(); 144 145 /* 146 * Leave reserved pages. The pages are not for anonymous pages. 147 */ 148 if (n <= totalreserve_pages) 149 goto error; 150 else 151 n -= totalreserve_pages; 152 153 /* 154 * Leave the last 3% for root 155 */ 156 if (!cap_sys_admin) 157 n -= n / 32; 158 free += n; 159 160 if (free > pages) 161 return 0; 162 163 goto error; 164 } 165 166 allowed = (totalram_pages - hugetlb_total_pages()) 167 * sysctl_overcommit_ratio / 100; 168 /* 169 * Leave the last 3% for root 170 */ 171 if (!cap_sys_admin) 172 allowed -= allowed / 32; 173 allowed += total_swap_pages; 174 175 /* Don't let a single process grow too big: 176 leave 3% of the size of this process for other processes */ 177 allowed -= mm->total_vm / 32; 178 179 /* 180 * cast `allowed' as a signed long because vm_committed_space 181 * sometimes has a negative value 182 */ 183 if (atomic_long_read(&vm_committed_space) < (long)allowed) 184 return 0; 185error: 186 vm_unacct_memory(pages); 187 188 return -ENOMEM; 189} 190 191/* 192 * Requires inode->i_mapping->i_mmap_lock 193 */ 194static void __remove_shared_vm_struct(struct vm_area_struct *vma, 195 struct file *file, struct address_space *mapping) 196{ 197 if (vma->vm_flags & VM_DENYWRITE) 198 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 199 if (vma->vm_flags & VM_SHARED) 200 mapping->i_mmap_writable--; 201 202 flush_dcache_mmap_lock(mapping); 203 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 204 list_del_init(&vma->shared.vm_set.list); 205 else 206 vma_prio_tree_remove(vma, &mapping->i_mmap); 207 flush_dcache_mmap_unlock(mapping); 208} 209 210/* 211 * Unlink a file-based vm structure from its prio_tree, to hide 212 * vma from rmap and vmtruncate before freeing its page tables. 213 */ 214void unlink_file_vma(struct vm_area_struct *vma) 215{ 216 struct file *file = vma->vm_file; 217 218 if (file) { 219 struct address_space *mapping = file->f_mapping; 220 spin_lock(&mapping->i_mmap_lock); 221 __remove_shared_vm_struct(vma, file, mapping); 222 spin_unlock(&mapping->i_mmap_lock); 223 } 224} 225 226/* 227 * Close a vm structure and free it, returning the next. 228 */ 229static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 230{ 231 struct vm_area_struct *next = vma->vm_next; 232 233 might_sleep(); 234 if (vma->vm_ops && vma->vm_ops->close) 235 vma->vm_ops->close(vma); 236 if (vma->vm_file) { 237 fput(vma->vm_file); 238 if (vma->vm_flags & VM_EXECUTABLE) 239 removed_exe_file_vma(vma->vm_mm); 240 } 241 mpol_put(vma_policy(vma)); 242 kmem_cache_free(vm_area_cachep, vma); 243 return next; 244} 245 246asmlinkage unsigned long sys_brk(unsigned long brk) 247{ 248 unsigned long rlim, retval; 249 unsigned long newbrk, oldbrk; 250 struct mm_struct *mm = current->mm; 251 unsigned long min_brk; 252 253 down_write(&mm->mmap_sem); 254 255#ifdef CONFIG_COMPAT_BRK 256 min_brk = mm->end_code; 257#else 258 min_brk = mm->start_brk; 259#endif 260 if (brk < min_brk) 261 goto out; 262 263 /* 264 * Check against rlimit here. If this check is done later after the test 265 * of oldbrk with newbrk then it can escape the test and let the data 266 * segment grow beyond its set limit the in case where the limit is 267 * not page aligned -Ram Gupta 268 */ 269 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 270 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + 271 (mm->end_data - mm->start_data) > rlim) 272 goto out; 273 274 newbrk = PAGE_ALIGN(brk); 275 oldbrk = PAGE_ALIGN(mm->brk); 276 if (oldbrk == newbrk) 277 goto set_brk; 278 279 /* Always allow shrinking brk. */ 280 if (brk <= mm->brk) { 281 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 282 goto set_brk; 283 goto out; 284 } 285 286 /* Check against existing mmap mappings. */ 287 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 288 goto out; 289 290 /* Ok, looks good - let it rip. */ 291 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 292 goto out; 293set_brk: 294 mm->brk = brk; 295out: 296 retval = mm->brk; 297 up_write(&mm->mmap_sem); 298 return retval; 299} 300 301#ifdef DEBUG_MM_RB 302static int browse_rb(struct rb_root *root) 303{ 304 int i = 0, j; 305 struct rb_node *nd, *pn = NULL; 306 unsigned long prev = 0, pend = 0; 307 308 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 309 struct vm_area_struct *vma; 310 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 311 if (vma->vm_start < prev) 312 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 313 if (vma->vm_start < pend) 314 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 315 if (vma->vm_start > vma->vm_end) 316 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 317 i++; 318 pn = nd; 319 prev = vma->vm_start; 320 pend = vma->vm_end; 321 } 322 j = 0; 323 for (nd = pn; nd; nd = rb_prev(nd)) { 324 j++; 325 } 326 if (i != j) 327 printk("backwards %d, forwards %d\n", j, i), i = 0; 328 return i; 329} 330 331void validate_mm(struct mm_struct *mm) 332{ 333 int bug = 0; 334 int i = 0; 335 struct vm_area_struct *tmp = mm->mmap; 336 while (tmp) { 337 tmp = tmp->vm_next; 338 i++; 339 } 340 if (i != mm->map_count) 341 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 342 i = browse_rb(&mm->mm_rb); 343 if (i != mm->map_count) 344 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 345 BUG_ON(bug); 346} 347#else 348#define validate_mm(mm) do { } while (0) 349#endif 350 351static struct vm_area_struct * 352find_vma_prepare(struct mm_struct *mm, unsigned long addr, 353 struct vm_area_struct **pprev, struct rb_node ***rb_link, 354 struct rb_node ** rb_parent) 355{ 356 struct vm_area_struct * vma; 357 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 358 359 __rb_link = &mm->mm_rb.rb_node; 360 rb_prev = __rb_parent = NULL; 361 vma = NULL; 362 363 while (*__rb_link) { 364 struct vm_area_struct *vma_tmp; 365 366 __rb_parent = *__rb_link; 367 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 368 369 if (vma_tmp->vm_end > addr) { 370 vma = vma_tmp; 371 if (vma_tmp->vm_start <= addr) 372 return vma; 373 __rb_link = &__rb_parent->rb_left; 374 } else { 375 rb_prev = __rb_parent; 376 __rb_link = &__rb_parent->rb_right; 377 } 378 } 379 380 *pprev = NULL; 381 if (rb_prev) 382 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 383 *rb_link = __rb_link; 384 *rb_parent = __rb_parent; 385 return vma; 386} 387 388static inline void 389__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 390 struct vm_area_struct *prev, struct rb_node *rb_parent) 391{ 392 if (prev) { 393 vma->vm_next = prev->vm_next; 394 prev->vm_next = vma; 395 } else { 396 mm->mmap = vma; 397 if (rb_parent) 398 vma->vm_next = rb_entry(rb_parent, 399 struct vm_area_struct, vm_rb); 400 else 401 vma->vm_next = NULL; 402 } 403} 404 405void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 406 struct rb_node **rb_link, struct rb_node *rb_parent) 407{ 408 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 409 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 410} 411 412static inline void __vma_link_file(struct vm_area_struct *vma) 413{ 414 struct file * file; 415 416 file = vma->vm_file; 417 if (file) { 418 struct address_space *mapping = file->f_mapping; 419 420 if (vma->vm_flags & VM_DENYWRITE) 421 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 422 if (vma->vm_flags & VM_SHARED) 423 mapping->i_mmap_writable++; 424 425 flush_dcache_mmap_lock(mapping); 426 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 427 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 428 else 429 vma_prio_tree_insert(vma, &mapping->i_mmap); 430 flush_dcache_mmap_unlock(mapping); 431 } 432} 433 434static void 435__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 436 struct vm_area_struct *prev, struct rb_node **rb_link, 437 struct rb_node *rb_parent) 438{ 439 __vma_link_list(mm, vma, prev, rb_parent); 440 __vma_link_rb(mm, vma, rb_link, rb_parent); 441 __anon_vma_link(vma); 442} 443 444static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 445 struct vm_area_struct *prev, struct rb_node **rb_link, 446 struct rb_node *rb_parent) 447{ 448 struct address_space *mapping = NULL; 449 450 if (vma->vm_file) 451 mapping = vma->vm_file->f_mapping; 452 453 if (mapping) { 454 spin_lock(&mapping->i_mmap_lock); 455 vma->vm_truncate_count = mapping->truncate_count; 456 } 457 anon_vma_lock(vma); 458 459 __vma_link(mm, vma, prev, rb_link, rb_parent); 460 __vma_link_file(vma); 461 462 anon_vma_unlock(vma); 463 if (mapping) 464 spin_unlock(&mapping->i_mmap_lock); 465 466 mm->map_count++; 467 validate_mm(mm); 468} 469 470/* 471 * Helper for vma_adjust in the split_vma insert case: 472 * insert vm structure into list and rbtree and anon_vma, 473 * but it has already been inserted into prio_tree earlier. 474 */ 475static void 476__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 477{ 478 struct vm_area_struct * __vma, * prev; 479 struct rb_node ** rb_link, * rb_parent; 480 481 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 482 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 483 __vma_link(mm, vma, prev, rb_link, rb_parent); 484 mm->map_count++; 485} 486 487static inline void 488__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 489 struct vm_area_struct *prev) 490{ 491 prev->vm_next = vma->vm_next; 492 rb_erase(&vma->vm_rb, &mm->mm_rb); 493 if (mm->mmap_cache == vma) 494 mm->mmap_cache = prev; 495} 496 497/* 498 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 499 * is already present in an i_mmap tree without adjusting the tree. 500 * The following helper function should be used when such adjustments 501 * are necessary. The "insert" vma (if any) is to be inserted 502 * before we drop the necessary locks. 503 */ 504void vma_adjust(struct vm_area_struct *vma, unsigned long start, 505 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 506{ 507 struct mm_struct *mm = vma->vm_mm; 508 struct vm_area_struct *next = vma->vm_next; 509 struct vm_area_struct *importer = NULL; 510 struct address_space *mapping = NULL; 511 struct prio_tree_root *root = NULL; 512 struct file *file = vma->vm_file; 513 struct anon_vma *anon_vma = NULL; 514 long adjust_next = 0; 515 int remove_next = 0; 516 517 if (next && !insert) { 518 if (end >= next->vm_end) { 519 /* 520 * vma expands, overlapping all the next, and 521 * perhaps the one after too (mprotect case 6). 522 */ 523again: remove_next = 1 + (end > next->vm_end); 524 end = next->vm_end; 525 anon_vma = next->anon_vma; 526 importer = vma; 527 } else if (end > next->vm_start) { 528 /* 529 * vma expands, overlapping part of the next: 530 * mprotect case 5 shifting the boundary up. 531 */ 532 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 533 anon_vma = next->anon_vma; 534 importer = vma; 535 } else if (end < vma->vm_end) { 536 /* 537 * vma shrinks, and !insert tells it's not 538 * split_vma inserting another: so it must be 539 * mprotect case 4 shifting the boundary down. 540 */ 541 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 542 anon_vma = next->anon_vma; 543 importer = next; 544 } 545 } 546 547 if (file) { 548 mapping = file->f_mapping; 549 if (!(vma->vm_flags & VM_NONLINEAR)) 550 root = &mapping->i_mmap; 551 spin_lock(&mapping->i_mmap_lock); 552 if (importer && 553 vma->vm_truncate_count != next->vm_truncate_count) { 554 /* 555 * unmap_mapping_range might be in progress: 556 * ensure that the expanding vma is rescanned. 557 */ 558 importer->vm_truncate_count = 0; 559 } 560 if (insert) { 561 insert->vm_truncate_count = vma->vm_truncate_count; 562 /* 563 * Put into prio_tree now, so instantiated pages 564 * are visible to arm/parisc __flush_dcache_page 565 * throughout; but we cannot insert into address 566 * space until vma start or end is updated. 567 */ 568 __vma_link_file(insert); 569 } 570 } 571 572 /* 573 * When changing only vma->vm_end, we don't really need 574 * anon_vma lock: but is that case worth optimizing out? 575 */ 576 if (vma->anon_vma) 577 anon_vma = vma->anon_vma; 578 if (anon_vma) { 579 spin_lock(&anon_vma->lock); 580 /* 581 * Easily overlooked: when mprotect shifts the boundary, 582 * make sure the expanding vma has anon_vma set if the 583 * shrinking vma had, to cover any anon pages imported. 584 */ 585 if (importer && !importer->anon_vma) { 586 importer->anon_vma = anon_vma; 587 __anon_vma_link(importer); 588 } 589 } 590 591 if (root) { 592 flush_dcache_mmap_lock(mapping); 593 vma_prio_tree_remove(vma, root); 594 if (adjust_next) 595 vma_prio_tree_remove(next, root); 596 } 597 598 vma->vm_start = start; 599 vma->vm_end = end; 600 vma->vm_pgoff = pgoff; 601 if (adjust_next) { 602 next->vm_start += adjust_next << PAGE_SHIFT; 603 next->vm_pgoff += adjust_next; 604 } 605 606 if (root) { 607 if (adjust_next) 608 vma_prio_tree_insert(next, root); 609 vma_prio_tree_insert(vma, root); 610 flush_dcache_mmap_unlock(mapping); 611 } 612 613 if (remove_next) { 614 /* 615 * vma_merge has merged next into vma, and needs 616 * us to remove next before dropping the locks. 617 */ 618 __vma_unlink(mm, next, vma); 619 if (file) 620 __remove_shared_vm_struct(next, file, mapping); 621 if (next->anon_vma) 622 __anon_vma_merge(vma, next); 623 } else if (insert) { 624 /* 625 * split_vma has split insert from vma, and needs 626 * us to insert it before dropping the locks 627 * (it may either follow vma or precede it). 628 */ 629 __insert_vm_struct(mm, insert); 630 } 631 632 if (anon_vma) 633 spin_unlock(&anon_vma->lock); 634 if (mapping) 635 spin_unlock(&mapping->i_mmap_lock); 636 637 if (remove_next) { 638 if (file) { 639 fput(file); 640 if (next->vm_flags & VM_EXECUTABLE) 641 removed_exe_file_vma(mm); 642 } 643 mm->map_count--; 644 mpol_put(vma_policy(next)); 645 kmem_cache_free(vm_area_cachep, next); 646 /* 647 * In mprotect's case 6 (see comments on vma_merge), 648 * we must remove another next too. It would clutter 649 * up the code too much to do both in one go. 650 */ 651 if (remove_next == 2) { 652 next = vma->vm_next; 653 goto again; 654 } 655 } 656 657 validate_mm(mm); 658} 659 660/* 661 * If the vma has a ->close operation then the driver probably needs to release 662 * per-vma resources, so we don't attempt to merge those. 663 */ 664#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) 665 666static inline int is_mergeable_vma(struct vm_area_struct *vma, 667 struct file *file, unsigned long vm_flags) 668{ 669 if (vma->vm_flags != vm_flags) 670 return 0; 671 if (vma->vm_file != file) 672 return 0; 673 if (vma->vm_ops && vma->vm_ops->close) 674 return 0; 675 return 1; 676} 677 678static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 679 struct anon_vma *anon_vma2) 680{ 681 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 682} 683 684/* 685 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 686 * in front of (at a lower virtual address and file offset than) the vma. 687 * 688 * We cannot merge two vmas if they have differently assigned (non-NULL) 689 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 690 * 691 * We don't check here for the merged mmap wrapping around the end of pagecache 692 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 693 * wrap, nor mmaps which cover the final page at index -1UL. 694 */ 695static int 696can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 697 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 698{ 699 if (is_mergeable_vma(vma, file, vm_flags) && 700 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 701 if (vma->vm_pgoff == vm_pgoff) 702 return 1; 703 } 704 return 0; 705} 706 707/* 708 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 709 * beyond (at a higher virtual address and file offset than) the vma. 710 * 711 * We cannot merge two vmas if they have differently assigned (non-NULL) 712 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 713 */ 714static int 715can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 716 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 717{ 718 if (is_mergeable_vma(vma, file, vm_flags) && 719 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 720 pgoff_t vm_pglen; 721 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 722 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 723 return 1; 724 } 725 return 0; 726} 727 728/* 729 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 730 * whether that can be merged with its predecessor or its successor. 731 * Or both (it neatly fills a hole). 732 * 733 * In most cases - when called for mmap, brk or mremap - [addr,end) is 734 * certain not to be mapped by the time vma_merge is called; but when 735 * called for mprotect, it is certain to be already mapped (either at 736 * an offset within prev, or at the start of next), and the flags of 737 * this area are about to be changed to vm_flags - and the no-change 738 * case has already been eliminated. 739 * 740 * The following mprotect cases have to be considered, where AAAA is 741 * the area passed down from mprotect_fixup, never extending beyond one 742 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 743 * 744 * AAAA AAAA AAAA AAAA 745 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 746 * cannot merge might become might become might become 747 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 748 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 749 * mremap move: PPPPNNNNNNNN 8 750 * AAAA 751 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 752 * might become case 1 below case 2 below case 3 below 753 * 754 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 755 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 756 */ 757struct vm_area_struct *vma_merge(struct mm_struct *mm, 758 struct vm_area_struct *prev, unsigned long addr, 759 unsigned long end, unsigned long vm_flags, 760 struct anon_vma *anon_vma, struct file *file, 761 pgoff_t pgoff, struct mempolicy *policy) 762{ 763 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 764 struct vm_area_struct *area, *next; 765 766 /* 767 * We later require that vma->vm_flags == vm_flags, 768 * so this tests vma->vm_flags & VM_SPECIAL, too. 769 */ 770 if (vm_flags & VM_SPECIAL) 771 return NULL; 772 773 if (prev) 774 next = prev->vm_next; 775 else 776 next = mm->mmap; 777 area = next; 778 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 779 next = next->vm_next; 780 781 /* 782 * Can it merge with the predecessor? 783 */ 784 if (prev && prev->vm_end == addr && 785 mpol_equal(vma_policy(prev), policy) && 786 can_vma_merge_after(prev, vm_flags, 787 anon_vma, file, pgoff)) { 788 /* 789 * OK, it can. Can we now merge in the successor as well? 790 */ 791 if (next && end == next->vm_start && 792 mpol_equal(policy, vma_policy(next)) && 793 can_vma_merge_before(next, vm_flags, 794 anon_vma, file, pgoff+pglen) && 795 is_mergeable_anon_vma(prev->anon_vma, 796 next->anon_vma)) { 797 /* cases 1, 6 */ 798 vma_adjust(prev, prev->vm_start, 799 next->vm_end, prev->vm_pgoff, NULL); 800 } else /* cases 2, 5, 7 */ 801 vma_adjust(prev, prev->vm_start, 802 end, prev->vm_pgoff, NULL); 803 return prev; 804 } 805 806 /* 807 * Can this new request be merged in front of next? 808 */ 809 if (next && end == next->vm_start && 810 mpol_equal(policy, vma_policy(next)) && 811 can_vma_merge_before(next, vm_flags, 812 anon_vma, file, pgoff+pglen)) { 813 if (prev && addr < prev->vm_end) /* case 4 */ 814 vma_adjust(prev, prev->vm_start, 815 addr, prev->vm_pgoff, NULL); 816 else /* cases 3, 8 */ 817 vma_adjust(area, addr, next->vm_end, 818 next->vm_pgoff - pglen, NULL); 819 return area; 820 } 821 822 return NULL; 823} 824 825/* 826 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 827 * neighbouring vmas for a suitable anon_vma, before it goes off 828 * to allocate a new anon_vma. It checks because a repetitive 829 * sequence of mprotects and faults may otherwise lead to distinct 830 * anon_vmas being allocated, preventing vma merge in subsequent 831 * mprotect. 832 */ 833struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 834{ 835 struct vm_area_struct *near; 836 unsigned long vm_flags; 837 838 near = vma->vm_next; 839 if (!near) 840 goto try_prev; 841 842 /* 843 * Since only mprotect tries to remerge vmas, match flags 844 * which might be mprotected into each other later on. 845 * Neither mlock nor madvise tries to remerge at present, 846 * so leave their flags as obstructing a merge. 847 */ 848 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 849 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 850 851 if (near->anon_vma && vma->vm_end == near->vm_start && 852 mpol_equal(vma_policy(vma), vma_policy(near)) && 853 can_vma_merge_before(near, vm_flags, 854 NULL, vma->vm_file, vma->vm_pgoff + 855 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 856 return near->anon_vma; 857try_prev: 858 /* 859 * It is potentially slow to have to call find_vma_prev here. 860 * But it's only on the first write fault on the vma, not 861 * every time, and we could devise a way to avoid it later 862 * (e.g. stash info in next's anon_vma_node when assigning 863 * an anon_vma, or when trying vma_merge). Another time. 864 */ 865 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 866 if (!near) 867 goto none; 868 869 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 870 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 871 872 if (near->anon_vma && near->vm_end == vma->vm_start && 873 mpol_equal(vma_policy(near), vma_policy(vma)) && 874 can_vma_merge_after(near, vm_flags, 875 NULL, vma->vm_file, vma->vm_pgoff)) 876 return near->anon_vma; 877none: 878 /* 879 * There's no absolute need to look only at touching neighbours: 880 * we could search further afield for "compatible" anon_vmas. 881 * But it would probably just be a waste of time searching, 882 * or lead to too many vmas hanging off the same anon_vma. 883 * We're trying to allow mprotect remerging later on, 884 * not trying to minimize memory used for anon_vmas. 885 */ 886 return NULL; 887} 888 889#ifdef CONFIG_PROC_FS 890void vm_stat_account(struct mm_struct *mm, unsigned long flags, 891 struct file *file, long pages) 892{ 893 const unsigned long stack_flags 894 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 895 896 if (file) { 897 mm->shared_vm += pages; 898 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 899 mm->exec_vm += pages; 900 } else if (flags & stack_flags) 901 mm->stack_vm += pages; 902 if (flags & (VM_RESERVED|VM_IO)) 903 mm->reserved_vm += pages; 904} 905#endif /* CONFIG_PROC_FS */ 906 907/* 908 * The caller must hold down_write(current->mm->mmap_sem). 909 */ 910 911unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 912 unsigned long len, unsigned long prot, 913 unsigned long flags, unsigned long pgoff) 914{ 915 struct mm_struct * mm = current->mm; 916 struct inode *inode; 917 unsigned int vm_flags; 918 int error; 919 int accountable = 1; 920 unsigned long reqprot = prot; 921 922 /* 923 * Does the application expect PROT_READ to imply PROT_EXEC? 924 * 925 * (the exception is when the underlying filesystem is noexec 926 * mounted, in which case we dont add PROT_EXEC.) 927 */ 928 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 929 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 930 prot |= PROT_EXEC; 931 932 if (!len) 933 return -EINVAL; 934 935 if (!(flags & MAP_FIXED)) 936 addr = round_hint_to_min(addr); 937 938 error = arch_mmap_check(addr, len, flags); 939 if (error) 940 return error; 941 942 /* Careful about overflows.. */ 943 len = PAGE_ALIGN(len); 944 if (!len || len > TASK_SIZE) 945 return -ENOMEM; 946 947 /* offset overflow? */ 948 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 949 return -EOVERFLOW; 950 951 /* Too many mappings? */ 952 if (mm->map_count > sysctl_max_map_count) 953 return -ENOMEM; 954 955 /* Obtain the address to map to. we verify (or select) it and ensure 956 * that it represents a valid section of the address space. 957 */ 958 addr = get_unmapped_area(file, addr, len, pgoff, flags); 959 if (addr & ~PAGE_MASK) 960 return addr; 961 962 /* Do simple checking here so the lower-level routines won't have 963 * to. we assume access permissions have been handled by the open 964 * of the memory object, so we don't do any here. 965 */ 966 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 967 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 968 969 if (flags & MAP_LOCKED) { 970 if (!can_do_mlock()) 971 return -EPERM; 972 vm_flags |= VM_LOCKED; 973 } 974 /* mlock MCL_FUTURE? */ 975 if (vm_flags & VM_LOCKED) { 976 unsigned long locked, lock_limit; 977 locked = len >> PAGE_SHIFT; 978 locked += mm->locked_vm; 979 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 980 lock_limit >>= PAGE_SHIFT; 981 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 982 return -EAGAIN; 983 } 984 985 inode = file ? file->f_path.dentry->d_inode : NULL; 986 987 if (file) { 988 switch (flags & MAP_TYPE) { 989 case MAP_SHARED: 990 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 991 return -EACCES; 992 993 /* 994 * Make sure we don't allow writing to an append-only 995 * file.. 996 */ 997 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 998 return -EACCES; 999 1000 /* 1001 * Make sure there are no mandatory locks on the file. 1002 */ 1003 if (locks_verify_locked(inode)) 1004 return -EAGAIN; 1005 1006 vm_flags |= VM_SHARED | VM_MAYSHARE; 1007 if (!(file->f_mode & FMODE_WRITE)) 1008 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1009 1010 /* fall through */ 1011 case MAP_PRIVATE: 1012 if (!(file->f_mode & FMODE_READ)) 1013 return -EACCES; 1014 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1015 if (vm_flags & VM_EXEC) 1016 return -EPERM; 1017 vm_flags &= ~VM_MAYEXEC; 1018 } 1019 if (is_file_hugepages(file)) 1020 accountable = 0; 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 vm_flags |= VM_SHARED | VM_MAYSHARE; 1033 break; 1034 case MAP_PRIVATE: 1035 /* 1036 * Set pgoff according to addr for anon_vma. 1037 */ 1038 pgoff = addr >> PAGE_SHIFT; 1039 break; 1040 default: 1041 return -EINVAL; 1042 } 1043 } 1044 1045 error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1046 if (error) 1047 return error; 1048 1049 return mmap_region(file, addr, len, flags, vm_flags, pgoff, 1050 accountable); 1051} 1052EXPORT_SYMBOL(do_mmap_pgoff); 1053 1054/* 1055 * Some shared mappigns will want the pages marked read-only 1056 * to track write events. If so, we'll downgrade vm_page_prot 1057 * to the private version (using protection_map[] without the 1058 * VM_SHARED bit). 1059 */ 1060int vma_wants_writenotify(struct vm_area_struct *vma) 1061{ 1062 unsigned int vm_flags = vma->vm_flags; 1063 1064 /* If it was private or non-writable, the write bit is already clear */ 1065 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1066 return 0; 1067 1068 /* The backer wishes to know when pages are first written to? */ 1069 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1070 return 1; 1071 1072 /* The open routine did something to the protections already? */ 1073 if (pgprot_val(vma->vm_page_prot) != 1074 pgprot_val(vm_get_page_prot(vm_flags))) 1075 return 0; 1076 1077 /* Specialty mapping? */ 1078 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) 1079 return 0; 1080 1081 /* Can the mapping track the dirty pages? */ 1082 return vma->vm_file && vma->vm_file->f_mapping && 1083 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1084} 1085 1086unsigned long mmap_region(struct file *file, unsigned long addr, 1087 unsigned long len, unsigned long flags, 1088 unsigned int vm_flags, unsigned long pgoff, 1089 int accountable) 1090{ 1091 struct mm_struct *mm = current->mm; 1092 struct vm_area_struct *vma, *prev; 1093 int correct_wcount = 0; 1094 int error; 1095 struct rb_node **rb_link, *rb_parent; 1096 unsigned long charged = 0; 1097 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; 1098 1099 /* Clear old maps */ 1100 error = -ENOMEM; 1101munmap_back: 1102 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1103 if (vma && vma->vm_start < addr + len) { 1104 if (do_munmap(mm, addr, len)) 1105 return -ENOMEM; 1106 goto munmap_back; 1107 } 1108 1109 /* Check against address space limit. */ 1110 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1111 return -ENOMEM; 1112 1113 if (flags & MAP_NORESERVE) 1114 vm_flags |= VM_NORESERVE; 1115 1116 if (accountable && (!(flags & MAP_NORESERVE) || 1117 sysctl_overcommit_memory == OVERCOMMIT_NEVER)) { 1118 if (vm_flags & VM_SHARED) { 1119 /* Check memory availability in shmem_file_setup? */ 1120 vm_flags |= VM_ACCOUNT; 1121 } else if (vm_flags & VM_WRITE) { 1122 /* 1123 * Private writable mapping: check memory availability 1124 */ 1125 charged = len >> PAGE_SHIFT; 1126 if (security_vm_enough_memory(charged)) 1127 return -ENOMEM; 1128 vm_flags |= VM_ACCOUNT; 1129 } 1130 } 1131 1132 /* 1133 * Can we just expand an old private anonymous mapping? 1134 * The VM_SHARED test is necessary because shmem_zero_setup 1135 * will create the file object for a shared anonymous map below. 1136 */ 1137 if (!file && !(vm_flags & VM_SHARED) && 1138 vma_merge(mm, prev, addr, addr + len, vm_flags, 1139 NULL, NULL, pgoff, NULL)) 1140 goto out; 1141 1142 /* 1143 * Determine the object being mapped and call the appropriate 1144 * specific mapper. the address has already been validated, but 1145 * not unmapped, but the maps are removed from the list. 1146 */ 1147 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1148 if (!vma) { 1149 error = -ENOMEM; 1150 goto unacct_error; 1151 } 1152 1153 vma->vm_mm = mm; 1154 vma->vm_start = addr; 1155 vma->vm_end = addr + len; 1156 vma->vm_flags = vm_flags; 1157 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1158 vma->vm_pgoff = pgoff; 1159 1160 if (file) { 1161 error = -EINVAL; 1162 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1163 goto free_vma; 1164 if (vm_flags & VM_DENYWRITE) { 1165 error = deny_write_access(file); 1166 if (error) 1167 goto free_vma; 1168 correct_wcount = 1; 1169 } 1170 vma->vm_file = file; 1171 get_file(file); 1172 error = file->f_op->mmap(file, vma); 1173 if (error) 1174 goto unmap_and_free_vma; 1175 if (vm_flags & VM_EXECUTABLE) 1176 added_exe_file_vma(mm); 1177 } else if (vm_flags & VM_SHARED) { 1178 error = shmem_zero_setup(vma); 1179 if (error) 1180 goto free_vma; 1181 } 1182 1183 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1184 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1185 * that memory reservation must be checked; but that reservation 1186 * belongs to shared memory object, not to vma: so now clear it. 1187 */ 1188 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1189 vma->vm_flags &= ~VM_ACCOUNT; 1190 1191 /* Can addr have changed?? 1192 * 1193 * Answer: Yes, several device drivers can do it in their 1194 * f_op->mmap method. -DaveM 1195 */ 1196 addr = vma->vm_start; 1197 pgoff = vma->vm_pgoff; 1198 vm_flags = vma->vm_flags; 1199 1200 if (vma_wants_writenotify(vma)) 1201 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); 1202 1203 if (file && vma_merge(mm, prev, addr, vma->vm_end, 1204 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1205 mpol_put(vma_policy(vma)); 1206 kmem_cache_free(vm_area_cachep, vma); 1207 fput(file); 1208 if (vm_flags & VM_EXECUTABLE) 1209 removed_exe_file_vma(mm); 1210 } else { 1211 vma_link(mm, vma, prev, rb_link, rb_parent); 1212 file = vma->vm_file; 1213 } 1214 1215 /* Once vma denies write, undo our temporary denial count */ 1216 if (correct_wcount) 1217 atomic_inc(&inode->i_writecount); 1218out: 1219 mm->total_vm += len >> PAGE_SHIFT; 1220 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1221 if (vm_flags & VM_LOCKED) { 1222 mm->locked_vm += len >> PAGE_SHIFT; 1223 make_pages_present(addr, addr + len); 1224 } 1225 if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) 1226 make_pages_present(addr, addr + len); 1227 return addr; 1228 1229unmap_and_free_vma: 1230 if (correct_wcount) 1231 atomic_inc(&inode->i_writecount); 1232 vma->vm_file = NULL; 1233 fput(file); 1234 1235 /* Undo any partial mapping done by a device driver. */ 1236 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1237 charged = 0; 1238free_vma: 1239 kmem_cache_free(vm_area_cachep, vma); 1240unacct_error: 1241 if (charged) 1242 vm_unacct_memory(charged); 1243 return error; 1244} 1245 1246/* Get an address range which is currently unmapped. 1247 * For shmat() with addr=0. 1248 * 1249 * Ugly calling convention alert: 1250 * Return value with the low bits set means error value, 1251 * ie 1252 * if (ret & ~PAGE_MASK) 1253 * error = ret; 1254 * 1255 * This function "knows" that -ENOMEM has the bits set. 1256 */ 1257#ifndef HAVE_ARCH_UNMAPPED_AREA 1258unsigned long 1259arch_get_unmapped_area(struct file *filp, unsigned long addr, 1260 unsigned long len, unsigned long pgoff, unsigned long flags) 1261{ 1262 struct mm_struct *mm = current->mm; 1263 struct vm_area_struct *vma; 1264 unsigned long start_addr; 1265 1266 if (len > TASK_SIZE) 1267 return -ENOMEM; 1268 1269 if (flags & MAP_FIXED) 1270 return addr; 1271 1272 if (addr) { 1273 addr = PAGE_ALIGN(addr); 1274 vma = find_vma(mm, addr); 1275 if (TASK_SIZE - len >= addr && 1276 (!vma || addr + len <= vma->vm_start)) 1277 return addr; 1278 } 1279 if (len > mm->cached_hole_size) { 1280 start_addr = addr = mm->free_area_cache; 1281 } else { 1282 start_addr = addr = TASK_UNMAPPED_BASE; 1283 mm->cached_hole_size = 0; 1284 } 1285 1286full_search: 1287 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1288 /* At this point: (!vma || addr < vma->vm_end). */ 1289 if (TASK_SIZE - len < addr) { 1290 /* 1291 * Start a new search - just in case we missed 1292 * some holes. 1293 */ 1294 if (start_addr != TASK_UNMAPPED_BASE) { 1295 addr = TASK_UNMAPPED_BASE; 1296 start_addr = addr; 1297 mm->cached_hole_size = 0; 1298 goto full_search; 1299 } 1300 return -ENOMEM; 1301 } 1302 if (!vma || addr + len <= vma->vm_start) { 1303 /* 1304 * Remember the place where we stopped the search: 1305 */ 1306 mm->free_area_cache = addr + len; 1307 return addr; 1308 } 1309 if (addr + mm->cached_hole_size < vma->vm_start) 1310 mm->cached_hole_size = vma->vm_start - addr; 1311 addr = vma->vm_end; 1312 } 1313} 1314#endif 1315 1316void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1317{ 1318 /* 1319 * Is this a new hole at the lowest possible address? 1320 */ 1321 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1322 mm->free_area_cache = addr; 1323 mm->cached_hole_size = ~0UL; 1324 } 1325} 1326 1327/* 1328 * This mmap-allocator allocates new areas top-down from below the 1329 * stack's low limit (the base): 1330 */ 1331#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1332unsigned long 1333arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1334 const unsigned long len, const unsigned long pgoff, 1335 const unsigned long flags) 1336{ 1337 struct vm_area_struct *vma; 1338 struct mm_struct *mm = current->mm; 1339 unsigned long addr = addr0; 1340 1341 /* requested length too big for entire address space */ 1342 if (len > TASK_SIZE) 1343 return -ENOMEM; 1344 1345 if (flags & MAP_FIXED) 1346 return addr; 1347 1348 /* requesting a specific address */ 1349 if (addr) { 1350 addr = PAGE_ALIGN(addr); 1351 vma = find_vma(mm, addr); 1352 if (TASK_SIZE - len >= addr && 1353 (!vma || addr + len <= vma->vm_start)) 1354 return addr; 1355 } 1356 1357 /* check if free_area_cache is useful for us */ 1358 if (len <= mm->cached_hole_size) { 1359 mm->cached_hole_size = 0; 1360 mm->free_area_cache = mm->mmap_base; 1361 } 1362 1363 /* either no address requested or can't fit in requested address hole */ 1364 addr = mm->free_area_cache; 1365 1366 /* make sure it can fit in the remaining address space */ 1367 if (addr > len) { 1368 vma = find_vma(mm, addr-len); 1369 if (!vma || addr <= vma->vm_start) 1370 /* remember the address as a hint for next time */ 1371 return (mm->free_area_cache = addr-len); 1372 } 1373 1374 if (mm->mmap_base < len) 1375 goto bottomup; 1376 1377 addr = mm->mmap_base-len; 1378 1379 do { 1380 /* 1381 * Lookup failure means no vma is above this address, 1382 * else if new region fits below vma->vm_start, 1383 * return with success: 1384 */ 1385 vma = find_vma(mm, addr); 1386 if (!vma || addr+len <= vma->vm_start) 1387 /* remember the address as a hint for next time */ 1388 return (mm->free_area_cache = addr); 1389 1390 /* remember the largest hole we saw so far */ 1391 if (addr + mm->cached_hole_size < vma->vm_start) 1392 mm->cached_hole_size = vma->vm_start - addr; 1393 1394 /* try just below the current vma->vm_start */ 1395 addr = vma->vm_start-len; 1396 } while (len < vma->vm_start); 1397 1398bottomup: 1399 /* 1400 * A failed mmap() very likely causes application failure, 1401 * so fall back to the bottom-up function here. This scenario 1402 * can happen with large stack limits and large mmap() 1403 * allocations. 1404 */ 1405 mm->cached_hole_size = ~0UL; 1406 mm->free_area_cache = TASK_UNMAPPED_BASE; 1407 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1408 /* 1409 * Restore the topdown base: 1410 */ 1411 mm->free_area_cache = mm->mmap_base; 1412 mm->cached_hole_size = ~0UL; 1413 1414 return addr; 1415} 1416#endif 1417 1418void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1419{ 1420 /* 1421 * Is this a new hole at the highest possible address? 1422 */ 1423 if (addr > mm->free_area_cache) 1424 mm->free_area_cache = addr; 1425 1426 /* dont allow allocations above current base */ 1427 if (mm->free_area_cache > mm->mmap_base) 1428 mm->free_area_cache = mm->mmap_base; 1429} 1430 1431unsigned long 1432get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1433 unsigned long pgoff, unsigned long flags) 1434{ 1435 unsigned long (*get_area)(struct file *, unsigned long, 1436 unsigned long, unsigned long, unsigned long); 1437 1438 get_area = current->mm->get_unmapped_area; 1439 if (file && file->f_op && file->f_op->get_unmapped_area) 1440 get_area = file->f_op->get_unmapped_area; 1441 addr = get_area(file, addr, len, pgoff, flags); 1442 if (IS_ERR_VALUE(addr)) 1443 return addr; 1444 1445 if (addr > TASK_SIZE - len) 1446 return -ENOMEM; 1447 if (addr & ~PAGE_MASK) 1448 return -EINVAL; 1449 1450 return arch_rebalance_pgtables(addr, len); 1451} 1452 1453EXPORT_SYMBOL(get_unmapped_area); 1454 1455/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1456struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1457{ 1458 struct vm_area_struct *vma = NULL; 1459 1460 if (mm) { 1461 /* Check the cache first. */ 1462 /* (Cache hit rate is typically around 35%.) */ 1463 vma = mm->mmap_cache; 1464 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1465 struct rb_node * rb_node; 1466 1467 rb_node = mm->mm_rb.rb_node; 1468 vma = NULL; 1469 1470 while (rb_node) { 1471 struct vm_area_struct * vma_tmp; 1472 1473 vma_tmp = rb_entry(rb_node, 1474 struct vm_area_struct, vm_rb); 1475 1476 if (vma_tmp->vm_end > addr) { 1477 vma = vma_tmp; 1478 if (vma_tmp->vm_start <= addr) 1479 break; 1480 rb_node = rb_node->rb_left; 1481 } else 1482 rb_node = rb_node->rb_right; 1483 } 1484 if (vma) 1485 mm->mmap_cache = vma; 1486 } 1487 } 1488 return vma; 1489} 1490 1491EXPORT_SYMBOL(find_vma); 1492 1493/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1494struct vm_area_struct * 1495find_vma_prev(struct mm_struct *mm, unsigned long addr, 1496 struct vm_area_struct **pprev) 1497{ 1498 struct vm_area_struct *vma = NULL, *prev = NULL; 1499 struct rb_node * rb_node; 1500 if (!mm) 1501 goto out; 1502 1503 /* Guard against addr being lower than the first VMA */ 1504 vma = mm->mmap; 1505 1506 /* Go through the RB tree quickly. */ 1507 rb_node = mm->mm_rb.rb_node; 1508 1509 while (rb_node) { 1510 struct vm_area_struct *vma_tmp; 1511 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1512 1513 if (addr < vma_tmp->vm_end) { 1514 rb_node = rb_node->rb_left; 1515 } else { 1516 prev = vma_tmp; 1517 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1518 break; 1519 rb_node = rb_node->rb_right; 1520 } 1521 } 1522 1523out: 1524 *pprev = prev; 1525 return prev ? prev->vm_next : vma; 1526} 1527 1528/* 1529 * Verify that the stack growth is acceptable and 1530 * update accounting. This is shared with both the 1531 * grow-up and grow-down cases. 1532 */ 1533static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1534{ 1535 struct mm_struct *mm = vma->vm_mm; 1536 struct rlimit *rlim = current->signal->rlim; 1537 unsigned long new_start; 1538 1539 /* address space limit tests */ 1540 if (!may_expand_vm(mm, grow)) 1541 return -ENOMEM; 1542 1543 /* Stack limit test */ 1544 if (size > rlim[RLIMIT_STACK].rlim_cur) 1545 return -ENOMEM; 1546 1547 /* mlock limit tests */ 1548 if (vma->vm_flags & VM_LOCKED) { 1549 unsigned long locked; 1550 unsigned long limit; 1551 locked = mm->locked_vm + grow; 1552 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1553 if (locked > limit && !capable(CAP_IPC_LOCK)) 1554 return -ENOMEM; 1555 } 1556 1557 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1558 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1559 vma->vm_end - size; 1560 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1561 return -EFAULT; 1562 1563 /* 1564 * Overcommit.. This must be the final test, as it will 1565 * update security statistics. 1566 */ 1567 if (security_vm_enough_memory(grow)) 1568 return -ENOMEM; 1569 1570 /* Ok, everything looks good - let it rip */ 1571 mm->total_vm += grow; 1572 if (vma->vm_flags & VM_LOCKED) 1573 mm->locked_vm += grow; 1574 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1575 return 0; 1576} 1577 1578#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1579/* 1580 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1581 * vma is the last one with address > vma->vm_end. Have to extend vma. 1582 */ 1583#ifndef CONFIG_IA64 1584static inline 1585#endif 1586int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1587{ 1588 int error; 1589 1590 if (!(vma->vm_flags & VM_GROWSUP)) 1591 return -EFAULT; 1592 1593 /* 1594 * We must make sure the anon_vma is allocated 1595 * so that the anon_vma locking is not a noop. 1596 */ 1597 if (unlikely(anon_vma_prepare(vma))) 1598 return -ENOMEM; 1599 anon_vma_lock(vma); 1600 1601 /* 1602 * vma->vm_start/vm_end cannot change under us because the caller 1603 * is required to hold the mmap_sem in read mode. We need the 1604 * anon_vma lock to serialize against concurrent expand_stacks. 1605 * Also guard against wrapping around to address 0. 1606 */ 1607 if (address < PAGE_ALIGN(address+4)) 1608 address = PAGE_ALIGN(address+4); 1609 else { 1610 anon_vma_unlock(vma); 1611 return -ENOMEM; 1612 } 1613 error = 0; 1614 1615 /* Somebody else might have raced and expanded it already */ 1616 if (address > vma->vm_end) { 1617 unsigned long size, grow; 1618 1619 size = address - vma->vm_start; 1620 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1621 1622 error = acct_stack_growth(vma, size, grow); 1623 if (!error) 1624 vma->vm_end = address; 1625 } 1626 anon_vma_unlock(vma); 1627 return error; 1628} 1629#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1630 1631/* 1632 * vma is the first one with address < vma->vm_start. Have to extend vma. 1633 */ 1634static inline int expand_downwards(struct vm_area_struct *vma, 1635 unsigned long address) 1636{ 1637 int error; 1638 1639 /* 1640 * We must make sure the anon_vma is allocated 1641 * so that the anon_vma locking is not a noop. 1642 */ 1643 if (unlikely(anon_vma_prepare(vma))) 1644 return -ENOMEM; 1645 1646 address &= PAGE_MASK; 1647 error = security_file_mmap(NULL, 0, 0, 0, address, 1); 1648 if (error) 1649 return error; 1650 1651 anon_vma_lock(vma); 1652 1653 /* 1654 * vma->vm_start/vm_end cannot change under us because the caller 1655 * is required to hold the mmap_sem in read mode. We need the 1656 * anon_vma lock to serialize against concurrent expand_stacks. 1657 */ 1658 1659 /* Somebody else might have raced and expanded it already */ 1660 if (address < vma->vm_start) { 1661 unsigned long size, grow; 1662 1663 size = vma->vm_end - address; 1664 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1665 1666 error = acct_stack_growth(vma, size, grow); 1667 if (!error) { 1668 vma->vm_start = address; 1669 vma->vm_pgoff -= grow; 1670 } 1671 } 1672 anon_vma_unlock(vma); 1673 return error; 1674} 1675 1676int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) 1677{ 1678 return expand_downwards(vma, address); 1679} 1680 1681#ifdef CONFIG_STACK_GROWSUP 1682int expand_stack(struct vm_area_struct *vma, unsigned long address) 1683{ 1684 return expand_upwards(vma, address); 1685} 1686 1687struct vm_area_struct * 1688find_extend_vma(struct mm_struct *mm, unsigned long addr) 1689{ 1690 struct vm_area_struct *vma, *prev; 1691 1692 addr &= PAGE_MASK; 1693 vma = find_vma_prev(mm, addr, &prev); 1694 if (vma && (vma->vm_start <= addr)) 1695 return vma; 1696 if (!prev || expand_stack(prev, addr)) 1697 return NULL; 1698 if (prev->vm_flags & VM_LOCKED) 1699 make_pages_present(addr, prev->vm_end); 1700 return prev; 1701} 1702#else 1703int expand_stack(struct vm_area_struct *vma, unsigned long address) 1704{ 1705 return expand_downwards(vma, address); 1706} 1707 1708struct vm_area_struct * 1709find_extend_vma(struct mm_struct * mm, unsigned long addr) 1710{ 1711 struct vm_area_struct * vma; 1712 unsigned long start; 1713 1714 addr &= PAGE_MASK; 1715 vma = find_vma(mm,addr); 1716 if (!vma) 1717 return NULL; 1718 if (vma->vm_start <= addr) 1719 return vma; 1720 if (!(vma->vm_flags & VM_GROWSDOWN)) 1721 return NULL; 1722 start = vma->vm_start; 1723 if (expand_stack(vma, addr)) 1724 return NULL; 1725 if (vma->vm_flags & VM_LOCKED) 1726 make_pages_present(addr, start); 1727 return vma; 1728} 1729#endif 1730 1731/* 1732 * Ok - we have the memory areas we should free on the vma list, 1733 * so release them, and do the vma updates. 1734 * 1735 * Called with the mm semaphore held. 1736 */ 1737static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1738{ 1739 /* Update high watermark before we lower total_vm */ 1740 update_hiwater_vm(mm); 1741 do { 1742 long nrpages = vma_pages(vma); 1743 1744 mm->total_vm -= nrpages; 1745 if (vma->vm_flags & VM_LOCKED) 1746 mm->locked_vm -= nrpages; 1747 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1748 vma = remove_vma(vma); 1749 } while (vma); 1750 validate_mm(mm); 1751} 1752 1753/* 1754 * Get rid of page table information in the indicated region. 1755 * 1756 * Called with the mm semaphore held. 1757 */ 1758static void unmap_region(struct mm_struct *mm, 1759 struct vm_area_struct *vma, struct vm_area_struct *prev, 1760 unsigned long start, unsigned long end) 1761{ 1762 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1763 struct mmu_gather *tlb; 1764 unsigned long nr_accounted = 0; 1765 1766 lru_add_drain(); 1767 tlb = tlb_gather_mmu(mm, 0); 1768 update_hiwater_rss(mm); 1769 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1770 vm_unacct_memory(nr_accounted); 1771 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1772 next? next->vm_start: 0); 1773 tlb_finish_mmu(tlb, start, end); 1774} 1775 1776/* 1777 * Create a list of vma's touched by the unmap, removing them from the mm's 1778 * vma list as we go.. 1779 */ 1780static void 1781detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1782 struct vm_area_struct *prev, unsigned long end) 1783{ 1784 struct vm_area_struct **insertion_point; 1785 struct vm_area_struct *tail_vma = NULL; 1786 unsigned long addr; 1787 1788 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1789 do { 1790 rb_erase(&vma->vm_rb, &mm->mm_rb); 1791 mm->map_count--; 1792 tail_vma = vma; 1793 vma = vma->vm_next; 1794 } while (vma && vma->vm_start < end); 1795 *insertion_point = vma; 1796 tail_vma->vm_next = NULL; 1797 if (mm->unmap_area == arch_unmap_area) 1798 addr = prev ? prev->vm_end : mm->mmap_base; 1799 else 1800 addr = vma ? vma->vm_start : mm->mmap_base; 1801 mm->unmap_area(mm, addr); 1802 mm->mmap_cache = NULL; /* Kill the cache. */ 1803} 1804 1805/* 1806 * Split a vma into two pieces at address 'addr', a new vma is allocated 1807 * either for the first part or the tail. 1808 */ 1809int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1810 unsigned long addr, int new_below) 1811{ 1812 struct mempolicy *pol; 1813 struct vm_area_struct *new; 1814 1815 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK)) 1816 return -EINVAL; 1817 1818 if (mm->map_count >= sysctl_max_map_count) 1819 return -ENOMEM; 1820 1821 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1822 if (!new) 1823 return -ENOMEM; 1824 1825 /* most fields are the same, copy all, and then fixup */ 1826 *new = *vma; 1827 1828 if (new_below) 1829 new->vm_end = addr; 1830 else { 1831 new->vm_start = addr; 1832 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1833 } 1834 1835 pol = mpol_dup(vma_policy(vma)); 1836 if (IS_ERR(pol)) { 1837 kmem_cache_free(vm_area_cachep, new); 1838 return PTR_ERR(pol); 1839 } 1840 vma_set_policy(new, pol); 1841 1842 if (new->vm_file) { 1843 get_file(new->vm_file); 1844 if (vma->vm_flags & VM_EXECUTABLE) 1845 added_exe_file_vma(mm); 1846 } 1847 1848 if (new->vm_ops && new->vm_ops->open) 1849 new->vm_ops->open(new); 1850 1851 if (new_below) 1852 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1853 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1854 else 1855 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1856 1857 return 0; 1858} 1859 1860/* Munmap is split into 2 main parts -- this part which finds 1861 * what needs doing, and the areas themselves, which do the 1862 * work. This now handles partial unmappings. 1863 * Jeremy Fitzhardinge <jeremy@goop.org> 1864 */ 1865int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1866{ 1867 unsigned long end; 1868 struct vm_area_struct *vma, *prev, *last; 1869 1870 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1871 return -EINVAL; 1872 1873 if ((len = PAGE_ALIGN(len)) == 0) 1874 return -EINVAL; 1875 1876 /* Find the first overlapping VMA */ 1877 vma = find_vma_prev(mm, start, &prev); 1878 if (!vma) 1879 return 0; 1880 /* we have start < vma->vm_end */ 1881 1882 /* if it doesn't overlap, we have nothing.. */ 1883 end = start + len; 1884 if (vma->vm_start >= end) 1885 return 0; 1886 1887 /* 1888 * If we need to split any vma, do it now to save pain later. 1889 * 1890 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1891 * unmapped vm_area_struct will remain in use: so lower split_vma 1892 * places tmp vma above, and higher split_vma places tmp vma below. 1893 */ 1894 if (start > vma->vm_start) { 1895 int error = split_vma(mm, vma, start, 0); 1896 if (error) 1897 return error; 1898 prev = vma; 1899 } 1900 1901 /* Does it split the last one? */ 1902 last = find_vma(mm, end); 1903 if (last && end > last->vm_start) { 1904 int error = split_vma(mm, last, end, 1); 1905 if (error) 1906 return error; 1907 } 1908 vma = prev? prev->vm_next: mm->mmap; 1909 1910 /* 1911 * Remove the vma's, and unmap the actual pages 1912 */ 1913 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1914 unmap_region(mm, vma, prev, start, end); 1915 1916 /* Fix up all other VM information */ 1917 remove_vma_list(mm, vma); 1918 1919 return 0; 1920} 1921 1922EXPORT_SYMBOL(do_munmap); 1923 1924asmlinkage long sys_munmap(unsigned long addr, size_t len) 1925{ 1926 int ret; 1927 struct mm_struct *mm = current->mm; 1928 1929 profile_munmap(addr); 1930 1931 down_write(&mm->mmap_sem); 1932 ret = do_munmap(mm, addr, len); 1933 up_write(&mm->mmap_sem); 1934 return ret; 1935} 1936 1937static inline void verify_mm_writelocked(struct mm_struct *mm) 1938{ 1939#ifdef CONFIG_DEBUG_VM 1940 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1941 WARN_ON(1); 1942 up_read(&mm->mmap_sem); 1943 } 1944#endif 1945} 1946 1947/* 1948 * this is really a simplified "do_mmap". it only handles 1949 * anonymous maps. eventually we may be able to do some 1950 * brk-specific accounting here. 1951 */ 1952unsigned long do_brk(unsigned long addr, unsigned long len) 1953{ 1954 struct mm_struct * mm = current->mm; 1955 struct vm_area_struct * vma, * prev; 1956 unsigned long flags; 1957 struct rb_node ** rb_link, * rb_parent; 1958 pgoff_t pgoff = addr >> PAGE_SHIFT; 1959 int error; 1960 1961 len = PAGE_ALIGN(len); 1962 if (!len) 1963 return addr; 1964 1965 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1966 return -EINVAL; 1967 1968 if (is_hugepage_only_range(mm, addr, len)) 1969 return -EINVAL; 1970 1971 error = security_file_mmap(NULL, 0, 0, 0, addr, 1); 1972 if (error) 1973 return error; 1974 1975 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1976 1977 error = arch_mmap_check(addr, len, flags); 1978 if (error) 1979 return error; 1980 1981 /* 1982 * mlock MCL_FUTURE? 1983 */ 1984 if (mm->def_flags & VM_LOCKED) { 1985 unsigned long locked, lock_limit; 1986 locked = len >> PAGE_SHIFT; 1987 locked += mm->locked_vm; 1988 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1989 lock_limit >>= PAGE_SHIFT; 1990 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1991 return -EAGAIN; 1992 } 1993 1994 /* 1995 * mm->mmap_sem is required to protect against another thread 1996 * changing the mappings in case we sleep. 1997 */ 1998 verify_mm_writelocked(mm); 1999 2000 /* 2001 * Clear old maps. this also does some error checking for us 2002 */ 2003 munmap_back: 2004 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2005 if (vma && vma->vm_start < addr + len) { 2006 if (do_munmap(mm, addr, len)) 2007 return -ENOMEM; 2008 goto munmap_back; 2009 } 2010 2011 /* Check against address space limits *after* clearing old maps... */ 2012 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 2013 return -ENOMEM; 2014 2015 if (mm->map_count > sysctl_max_map_count) 2016 return -ENOMEM; 2017 2018 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 2019 return -ENOMEM; 2020 2021 /* Can we just expand an old private anonymous mapping? */ 2022 if (vma_merge(mm, prev, addr, addr + len, flags, 2023 NULL, NULL, pgoff, NULL)) 2024 goto out; 2025 2026 /* 2027 * create a vma struct for an anonymous mapping 2028 */ 2029 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2030 if (!vma) { 2031 vm_unacct_memory(len >> PAGE_SHIFT); 2032 return -ENOMEM; 2033 } 2034 2035 vma->vm_mm = mm; 2036 vma->vm_start = addr; 2037 vma->vm_end = addr + len; 2038 vma->vm_pgoff = pgoff; 2039 vma->vm_flags = flags; 2040 vma->vm_page_prot = vm_get_page_prot(flags); 2041 vma_link(mm, vma, prev, rb_link, rb_parent); 2042out: 2043 mm->total_vm += len >> PAGE_SHIFT; 2044 if (flags & VM_LOCKED) { 2045 mm->locked_vm += len >> PAGE_SHIFT; 2046 make_pages_present(addr, addr + len); 2047 } 2048 return addr; 2049} 2050 2051EXPORT_SYMBOL(do_brk); 2052 2053/* Release all mmaps. */ 2054void exit_mmap(struct mm_struct *mm) 2055{ 2056 struct mmu_gather *tlb; 2057 struct vm_area_struct *vma = mm->mmap; 2058 unsigned long nr_accounted = 0; 2059 unsigned long end; 2060 2061 /* mm's last user has gone, and its about to be pulled down */ 2062 arch_exit_mmap(mm); 2063 2064 lru_add_drain(); 2065 flush_cache_mm(mm); 2066 tlb = tlb_gather_mmu(mm, 1); 2067 /* Don't update_hiwater_rss(mm) here, do_exit already did */ 2068 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2069 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 2070 vm_unacct_memory(nr_accounted); 2071 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); 2072 tlb_finish_mmu(tlb, 0, end); 2073 2074 /* 2075 * Walk the list again, actually closing and freeing it, 2076 * with preemption enabled, without holding any MM locks. 2077 */ 2078 while (vma) 2079 vma = remove_vma(vma); 2080 2081 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2082} 2083 2084/* Insert vm structure into process list sorted by address 2085 * and into the inode's i_mmap tree. If vm_file is non-NULL 2086 * then i_mmap_lock is taken here. 2087 */ 2088int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 2089{ 2090 struct vm_area_struct * __vma, * prev; 2091 struct rb_node ** rb_link, * rb_parent; 2092 2093 /* 2094 * The vm_pgoff of a purely anonymous vma should be irrelevant 2095 * until its first write fault, when page's anon_vma and index 2096 * are set. But now set the vm_pgoff it will almost certainly 2097 * end up with (unless mremap moves it elsewhere before that 2098 * first wfault), so /proc/pid/maps tells a consistent story. 2099 * 2100 * By setting it to reflect the virtual start address of the 2101 * vma, merges and splits can happen in a seamless way, just 2102 * using the existing file pgoff checks and manipulations. 2103 * Similarly in do_mmap_pgoff and in do_brk. 2104 */ 2105 if (!vma->vm_file) { 2106 BUG_ON(vma->anon_vma); 2107 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2108 } 2109 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2110 if (__vma && __vma->vm_start < vma->vm_end) 2111 return -ENOMEM; 2112 if ((vma->vm_flags & VM_ACCOUNT) && 2113 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2114 return -ENOMEM; 2115 vma_link(mm, vma, prev, rb_link, rb_parent); 2116 return 0; 2117} 2118 2119/* 2120 * Copy the vma structure to a new location in the same mm, 2121 * prior to moving page table entries, to effect an mremap move. 2122 */ 2123struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2124 unsigned long addr, unsigned long len, pgoff_t pgoff) 2125{ 2126 struct vm_area_struct *vma = *vmap; 2127 unsigned long vma_start = vma->vm_start; 2128 struct mm_struct *mm = vma->vm_mm; 2129 struct vm_area_struct *new_vma, *prev; 2130 struct rb_node **rb_link, *rb_parent; 2131 struct mempolicy *pol; 2132 2133 /* 2134 * If anonymous vma has not yet been faulted, update new pgoff 2135 * to match new location, to increase its chance of merging. 2136 */ 2137 if (!vma->vm_file && !vma->anon_vma) 2138 pgoff = addr >> PAGE_SHIFT; 2139 2140 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2141 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2142 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2143 if (new_vma) { 2144 /* 2145 * Source vma may have been merged into new_vma 2146 */ 2147 if (vma_start >= new_vma->vm_start && 2148 vma_start < new_vma->vm_end) 2149 *vmap = new_vma; 2150 } else { 2151 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2152 if (new_vma) { 2153 *new_vma = *vma; 2154 pol = mpol_dup(vma_policy(vma)); 2155 if (IS_ERR(pol)) { 2156 kmem_cache_free(vm_area_cachep, new_vma); 2157 return NULL; 2158 } 2159 vma_set_policy(new_vma, pol); 2160 new_vma->vm_start = addr; 2161 new_vma->vm_end = addr + len; 2162 new_vma->vm_pgoff = pgoff; 2163 if (new_vma->vm_file) { 2164 get_file(new_vma->vm_file); 2165 if (vma->vm_flags & VM_EXECUTABLE) 2166 added_exe_file_vma(mm); 2167 } 2168 if (new_vma->vm_ops && new_vma->vm_ops->open) 2169 new_vma->vm_ops->open(new_vma); 2170 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2171 } 2172 } 2173 return new_vma; 2174} 2175 2176/* 2177 * Return true if the calling process may expand its vm space by the passed 2178 * number of pages 2179 */ 2180int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2181{ 2182 unsigned long cur = mm->total_vm; /* pages */ 2183 unsigned long lim; 2184 2185 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2186 2187 if (cur + npages > lim) 2188 return 0; 2189 return 1; 2190} 2191 2192 2193static int special_mapping_fault(struct vm_area_struct *vma, 2194 struct vm_fault *vmf) 2195{ 2196 pgoff_t pgoff; 2197 struct page **pages; 2198 2199 /* 2200 * special mappings have no vm_file, and in that case, the mm 2201 * uses vm_pgoff internally. So we have to subtract it from here. 2202 * We are allowed to do this because we are the mm; do not copy 2203 * this code into drivers! 2204 */ 2205 pgoff = vmf->pgoff - vma->vm_pgoff; 2206 2207 for (pages = vma->vm_private_data; pgoff && *pages; ++pages) 2208 pgoff--; 2209 2210 if (*pages) { 2211 struct page *page = *pages; 2212 get_page(page); 2213 vmf->page = page; 2214 return 0; 2215 } 2216 2217 return VM_FAULT_SIGBUS; 2218} 2219 2220/* 2221 * Having a close hook prevents vma merging regardless of flags. 2222 */ 2223static void special_mapping_close(struct vm_area_struct *vma) 2224{ 2225} 2226 2227static struct vm_operations_struct special_mapping_vmops = { 2228 .close = special_mapping_close, 2229 .fault = special_mapping_fault, 2230}; 2231 2232/* 2233 * Called with mm->mmap_sem held for writing. 2234 * Insert a new vma covering the given region, with the given flags. 2235 * Its pages are supplied by the given array of struct page *. 2236 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2237 * The region past the last page supplied will always produce SIGBUS. 2238 * The array pointer and the pages it points to are assumed to stay alive 2239 * for as long as this mapping might exist. 2240 */ 2241int install_special_mapping(struct mm_struct *mm, 2242 unsigned long addr, unsigned long len, 2243 unsigned long vm_flags, struct page **pages) 2244{ 2245 struct vm_area_struct *vma; 2246 2247 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2248 if (unlikely(vma == NULL)) 2249 return -ENOMEM; 2250 2251 vma->vm_mm = mm; 2252 vma->vm_start = addr; 2253 vma->vm_end = addr + len; 2254 2255 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; 2256 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 2257 2258 vma->vm_ops = &special_mapping_vmops; 2259 vma->vm_private_data = pages; 2260 2261 if (unlikely(insert_vm_struct(mm, vma))) { 2262 kmem_cache_free(vm_area_cachep, vma); 2263 return -ENOMEM; 2264 } 2265 2266 mm->total_vm += len >> PAGE_SHIFT; 2267 2268 return 0; 2269} 2270