mmap.c revision 4af3c9cc4fad54c3627e9afebf905aafde5690ed
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 184EXPORT_SYMBOL(__vm_enough_memory); 185 186/* 187 * Requires inode->i_mapping->i_mmap_lock 188 */ 189static void __remove_shared_vm_struct(struct vm_area_struct *vma, 190 struct file *file, struct address_space *mapping) 191{ 192 if (vma->vm_flags & VM_DENYWRITE) 193 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 194 if (vma->vm_flags & VM_SHARED) 195 mapping->i_mmap_writable--; 196 197 flush_dcache_mmap_lock(mapping); 198 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 199 list_del_init(&vma->shared.vm_set.list); 200 else 201 vma_prio_tree_remove(vma, &mapping->i_mmap); 202 flush_dcache_mmap_unlock(mapping); 203} 204 205/* 206 * Unlink a file-based vm structure from its prio_tree, to hide 207 * vma from rmap and vmtruncate before freeing its page tables. 208 */ 209void unlink_file_vma(struct vm_area_struct *vma) 210{ 211 struct file *file = vma->vm_file; 212 213 if (file) { 214 struct address_space *mapping = file->f_mapping; 215 spin_lock(&mapping->i_mmap_lock); 216 __remove_shared_vm_struct(vma, file, mapping); 217 spin_unlock(&mapping->i_mmap_lock); 218 } 219} 220 221/* 222 * Close a vm structure and free it, returning the next. 223 */ 224static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 225{ 226 struct vm_area_struct *next = vma->vm_next; 227 228 might_sleep(); 229 if (vma->vm_ops && vma->vm_ops->close) 230 vma->vm_ops->close(vma); 231 if (vma->vm_file) 232 fput(vma->vm_file); 233 mpol_free(vma_policy(vma)); 234 kmem_cache_free(vm_area_cachep, vma); 235 return next; 236} 237 238asmlinkage unsigned long sys_brk(unsigned long brk) 239{ 240 unsigned long rlim, retval; 241 unsigned long newbrk, oldbrk; 242 struct mm_struct *mm = current->mm; 243 244 down_write(&mm->mmap_sem); 245 246 if (brk < mm->end_code) 247 goto out; 248 249 /* 250 * Check against rlimit here. If this check is done later after the test 251 * of oldbrk with newbrk then it can escape the test and let the data 252 * segment grow beyond its set limit the in case where the limit is 253 * not page aligned -Ram Gupta 254 */ 255 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 256 if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) 257 goto out; 258 259 newbrk = PAGE_ALIGN(brk); 260 oldbrk = PAGE_ALIGN(mm->brk); 261 if (oldbrk == newbrk) 262 goto set_brk; 263 264 /* Always allow shrinking brk. */ 265 if (brk <= mm->brk) { 266 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 267 goto set_brk; 268 goto out; 269 } 270 271 /* Check against existing mmap mappings. */ 272 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 273 goto out; 274 275 /* Ok, looks good - let it rip. */ 276 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 277 goto out; 278set_brk: 279 mm->brk = brk; 280out: 281 retval = mm->brk; 282 up_write(&mm->mmap_sem); 283 return retval; 284} 285 286#ifdef DEBUG_MM_RB 287static int browse_rb(struct rb_root *root) 288{ 289 int i = 0, j; 290 struct rb_node *nd, *pn = NULL; 291 unsigned long prev = 0, pend = 0; 292 293 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 294 struct vm_area_struct *vma; 295 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 296 if (vma->vm_start < prev) 297 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 298 if (vma->vm_start < pend) 299 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 300 if (vma->vm_start > vma->vm_end) 301 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 302 i++; 303 pn = nd; 304 prev = vma->vm_start; 305 pend = vma->vm_end; 306 } 307 j = 0; 308 for (nd = pn; nd; nd = rb_prev(nd)) { 309 j++; 310 } 311 if (i != j) 312 printk("backwards %d, forwards %d\n", j, i), i = 0; 313 return i; 314} 315 316void validate_mm(struct mm_struct *mm) 317{ 318 int bug = 0; 319 int i = 0; 320 struct vm_area_struct *tmp = mm->mmap; 321 while (tmp) { 322 tmp = tmp->vm_next; 323 i++; 324 } 325 if (i != mm->map_count) 326 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 327 i = browse_rb(&mm->mm_rb); 328 if (i != mm->map_count) 329 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 330 BUG_ON(bug); 331} 332#else 333#define validate_mm(mm) do { } while (0) 334#endif 335 336static struct vm_area_struct * 337find_vma_prepare(struct mm_struct *mm, unsigned long addr, 338 struct vm_area_struct **pprev, struct rb_node ***rb_link, 339 struct rb_node ** rb_parent) 340{ 341 struct vm_area_struct * vma; 342 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 343 344 __rb_link = &mm->mm_rb.rb_node; 345 rb_prev = __rb_parent = NULL; 346 vma = NULL; 347 348 while (*__rb_link) { 349 struct vm_area_struct *vma_tmp; 350 351 __rb_parent = *__rb_link; 352 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 353 354 if (vma_tmp->vm_end > addr) { 355 vma = vma_tmp; 356 if (vma_tmp->vm_start <= addr) 357 return vma; 358 __rb_link = &__rb_parent->rb_left; 359 } else { 360 rb_prev = __rb_parent; 361 __rb_link = &__rb_parent->rb_right; 362 } 363 } 364 365 *pprev = NULL; 366 if (rb_prev) 367 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 368 *rb_link = __rb_link; 369 *rb_parent = __rb_parent; 370 return vma; 371} 372 373static inline void 374__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 375 struct vm_area_struct *prev, struct rb_node *rb_parent) 376{ 377 if (prev) { 378 vma->vm_next = prev->vm_next; 379 prev->vm_next = vma; 380 } else { 381 mm->mmap = vma; 382 if (rb_parent) 383 vma->vm_next = rb_entry(rb_parent, 384 struct vm_area_struct, vm_rb); 385 else 386 vma->vm_next = NULL; 387 } 388} 389 390void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 391 struct rb_node **rb_link, struct rb_node *rb_parent) 392{ 393 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 394 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 395} 396 397static inline void __vma_link_file(struct vm_area_struct *vma) 398{ 399 struct file * file; 400 401 file = vma->vm_file; 402 if (file) { 403 struct address_space *mapping = file->f_mapping; 404 405 if (vma->vm_flags & VM_DENYWRITE) 406 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 407 if (vma->vm_flags & VM_SHARED) 408 mapping->i_mmap_writable++; 409 410 flush_dcache_mmap_lock(mapping); 411 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 412 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 413 else 414 vma_prio_tree_insert(vma, &mapping->i_mmap); 415 flush_dcache_mmap_unlock(mapping); 416 } 417} 418 419static void 420__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 421 struct vm_area_struct *prev, struct rb_node **rb_link, 422 struct rb_node *rb_parent) 423{ 424 __vma_link_list(mm, vma, prev, rb_parent); 425 __vma_link_rb(mm, vma, rb_link, rb_parent); 426 __anon_vma_link(vma); 427} 428 429static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 430 struct vm_area_struct *prev, struct rb_node **rb_link, 431 struct rb_node *rb_parent) 432{ 433 struct address_space *mapping = NULL; 434 435 if (vma->vm_file) 436 mapping = vma->vm_file->f_mapping; 437 438 if (mapping) { 439 spin_lock(&mapping->i_mmap_lock); 440 vma->vm_truncate_count = mapping->truncate_count; 441 } 442 anon_vma_lock(vma); 443 444 __vma_link(mm, vma, prev, rb_link, rb_parent); 445 __vma_link_file(vma); 446 447 anon_vma_unlock(vma); 448 if (mapping) 449 spin_unlock(&mapping->i_mmap_lock); 450 451 mm->map_count++; 452 validate_mm(mm); 453} 454 455/* 456 * Helper for vma_adjust in the split_vma insert case: 457 * insert vm structure into list and rbtree and anon_vma, 458 * but it has already been inserted into prio_tree earlier. 459 */ 460static void 461__insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 462{ 463 struct vm_area_struct * __vma, * prev; 464 struct rb_node ** rb_link, * rb_parent; 465 466 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 467 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 468 __vma_link(mm, vma, prev, rb_link, rb_parent); 469 mm->map_count++; 470} 471 472static inline void 473__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 474 struct vm_area_struct *prev) 475{ 476 prev->vm_next = vma->vm_next; 477 rb_erase(&vma->vm_rb, &mm->mm_rb); 478 if (mm->mmap_cache == vma) 479 mm->mmap_cache = prev; 480} 481 482/* 483 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 484 * is already present in an i_mmap tree without adjusting the tree. 485 * The following helper function should be used when such adjustments 486 * are necessary. The "insert" vma (if any) is to be inserted 487 * before we drop the necessary locks. 488 */ 489void vma_adjust(struct vm_area_struct *vma, unsigned long start, 490 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 491{ 492 struct mm_struct *mm = vma->vm_mm; 493 struct vm_area_struct *next = vma->vm_next; 494 struct vm_area_struct *importer = NULL; 495 struct address_space *mapping = NULL; 496 struct prio_tree_root *root = NULL; 497 struct file *file = vma->vm_file; 498 struct anon_vma *anon_vma = NULL; 499 long adjust_next = 0; 500 int remove_next = 0; 501 502 if (next && !insert) { 503 if (end >= next->vm_end) { 504 /* 505 * vma expands, overlapping all the next, and 506 * perhaps the one after too (mprotect case 6). 507 */ 508again: remove_next = 1 + (end > next->vm_end); 509 end = next->vm_end; 510 anon_vma = next->anon_vma; 511 importer = vma; 512 } else if (end > next->vm_start) { 513 /* 514 * vma expands, overlapping part of the next: 515 * mprotect case 5 shifting the boundary up. 516 */ 517 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 518 anon_vma = next->anon_vma; 519 importer = vma; 520 } else if (end < vma->vm_end) { 521 /* 522 * vma shrinks, and !insert tells it's not 523 * split_vma inserting another: so it must be 524 * mprotect case 4 shifting the boundary down. 525 */ 526 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 527 anon_vma = next->anon_vma; 528 importer = next; 529 } 530 } 531 532 if (file) { 533 mapping = file->f_mapping; 534 if (!(vma->vm_flags & VM_NONLINEAR)) 535 root = &mapping->i_mmap; 536 spin_lock(&mapping->i_mmap_lock); 537 if (importer && 538 vma->vm_truncate_count != next->vm_truncate_count) { 539 /* 540 * unmap_mapping_range might be in progress: 541 * ensure that the expanding vma is rescanned. 542 */ 543 importer->vm_truncate_count = 0; 544 } 545 if (insert) { 546 insert->vm_truncate_count = vma->vm_truncate_count; 547 /* 548 * Put into prio_tree now, so instantiated pages 549 * are visible to arm/parisc __flush_dcache_page 550 * throughout; but we cannot insert into address 551 * space until vma start or end is updated. 552 */ 553 __vma_link_file(insert); 554 } 555 } 556 557 /* 558 * When changing only vma->vm_end, we don't really need 559 * anon_vma lock: but is that case worth optimizing out? 560 */ 561 if (vma->anon_vma) 562 anon_vma = vma->anon_vma; 563 if (anon_vma) { 564 spin_lock(&anon_vma->lock); 565 /* 566 * Easily overlooked: when mprotect shifts the boundary, 567 * make sure the expanding vma has anon_vma set if the 568 * shrinking vma had, to cover any anon pages imported. 569 */ 570 if (importer && !importer->anon_vma) { 571 importer->anon_vma = anon_vma; 572 __anon_vma_link(importer); 573 } 574 } 575 576 if (root) { 577 flush_dcache_mmap_lock(mapping); 578 vma_prio_tree_remove(vma, root); 579 if (adjust_next) 580 vma_prio_tree_remove(next, root); 581 } 582 583 vma->vm_start = start; 584 vma->vm_end = end; 585 vma->vm_pgoff = pgoff; 586 if (adjust_next) { 587 next->vm_start += adjust_next << PAGE_SHIFT; 588 next->vm_pgoff += adjust_next; 589 } 590 591 if (root) { 592 if (adjust_next) 593 vma_prio_tree_insert(next, root); 594 vma_prio_tree_insert(vma, root); 595 flush_dcache_mmap_unlock(mapping); 596 } 597 598 if (remove_next) { 599 /* 600 * vma_merge has merged next into vma, and needs 601 * us to remove next before dropping the locks. 602 */ 603 __vma_unlink(mm, next, vma); 604 if (file) 605 __remove_shared_vm_struct(next, file, mapping); 606 if (next->anon_vma) 607 __anon_vma_merge(vma, next); 608 } else if (insert) { 609 /* 610 * split_vma has split insert from vma, and needs 611 * us to insert it before dropping the locks 612 * (it may either follow vma or precede it). 613 */ 614 __insert_vm_struct(mm, insert); 615 } 616 617 if (anon_vma) 618 spin_unlock(&anon_vma->lock); 619 if (mapping) 620 spin_unlock(&mapping->i_mmap_lock); 621 622 if (remove_next) { 623 if (file) 624 fput(file); 625 mm->map_count--; 626 mpol_free(vma_policy(next)); 627 kmem_cache_free(vm_area_cachep, next); 628 /* 629 * In mprotect's case 6 (see comments on vma_merge), 630 * we must remove another next too. It would clutter 631 * up the code too much to do both in one go. 632 */ 633 if (remove_next == 2) { 634 next = vma->vm_next; 635 goto again; 636 } 637 } 638 639 validate_mm(mm); 640} 641 642/* 643 * If the vma has a ->close operation then the driver probably needs to release 644 * per-vma resources, so we don't attempt to merge those. 645 */ 646#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP) 647 648static inline int is_mergeable_vma(struct vm_area_struct *vma, 649 struct file *file, unsigned long vm_flags) 650{ 651 if (vma->vm_flags != vm_flags) 652 return 0; 653 if (vma->vm_file != file) 654 return 0; 655 if (vma->vm_ops && vma->vm_ops->close) 656 return 0; 657 return 1; 658} 659 660static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 661 struct anon_vma *anon_vma2) 662{ 663 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 664} 665 666/* 667 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 668 * in front of (at a lower virtual address and file offset than) the vma. 669 * 670 * We cannot merge two vmas if they have differently assigned (non-NULL) 671 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 672 * 673 * We don't check here for the merged mmap wrapping around the end of pagecache 674 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 675 * wrap, nor mmaps which cover the final page at index -1UL. 676 */ 677static int 678can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 679 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 680{ 681 if (is_mergeable_vma(vma, file, vm_flags) && 682 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 683 if (vma->vm_pgoff == vm_pgoff) 684 return 1; 685 } 686 return 0; 687} 688 689/* 690 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 691 * beyond (at a higher virtual address and file offset than) the vma. 692 * 693 * We cannot merge two vmas if they have differently assigned (non-NULL) 694 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 695 */ 696static int 697can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 698 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 699{ 700 if (is_mergeable_vma(vma, file, vm_flags) && 701 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 702 pgoff_t vm_pglen; 703 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 704 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 705 return 1; 706 } 707 return 0; 708} 709 710/* 711 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 712 * whether that can be merged with its predecessor or its successor. 713 * Or both (it neatly fills a hole). 714 * 715 * In most cases - when called for mmap, brk or mremap - [addr,end) is 716 * certain not to be mapped by the time vma_merge is called; but when 717 * called for mprotect, it is certain to be already mapped (either at 718 * an offset within prev, or at the start of next), and the flags of 719 * this area are about to be changed to vm_flags - and the no-change 720 * case has already been eliminated. 721 * 722 * The following mprotect cases have to be considered, where AAAA is 723 * the area passed down from mprotect_fixup, never extending beyond one 724 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 725 * 726 * AAAA AAAA AAAA AAAA 727 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 728 * cannot merge might become might become might become 729 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 730 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 731 * mremap move: PPPPNNNNNNNN 8 732 * AAAA 733 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 734 * might become case 1 below case 2 below case 3 below 735 * 736 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 737 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 738 */ 739struct vm_area_struct *vma_merge(struct mm_struct *mm, 740 struct vm_area_struct *prev, unsigned long addr, 741 unsigned long end, unsigned long vm_flags, 742 struct anon_vma *anon_vma, struct file *file, 743 pgoff_t pgoff, struct mempolicy *policy) 744{ 745 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 746 struct vm_area_struct *area, *next; 747 748 /* 749 * We later require that vma->vm_flags == vm_flags, 750 * so this tests vma->vm_flags & VM_SPECIAL, too. 751 */ 752 if (vm_flags & VM_SPECIAL) 753 return NULL; 754 755 if (prev) 756 next = prev->vm_next; 757 else 758 next = mm->mmap; 759 area = next; 760 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 761 next = next->vm_next; 762 763 /* 764 * Can it merge with the predecessor? 765 */ 766 if (prev && prev->vm_end == addr && 767 mpol_equal(vma_policy(prev), policy) && 768 can_vma_merge_after(prev, vm_flags, 769 anon_vma, file, pgoff)) { 770 /* 771 * OK, it can. Can we now merge in the successor as well? 772 */ 773 if (next && end == next->vm_start && 774 mpol_equal(policy, vma_policy(next)) && 775 can_vma_merge_before(next, vm_flags, 776 anon_vma, file, pgoff+pglen) && 777 is_mergeable_anon_vma(prev->anon_vma, 778 next->anon_vma)) { 779 /* cases 1, 6 */ 780 vma_adjust(prev, prev->vm_start, 781 next->vm_end, prev->vm_pgoff, NULL); 782 } else /* cases 2, 5, 7 */ 783 vma_adjust(prev, prev->vm_start, 784 end, prev->vm_pgoff, NULL); 785 return prev; 786 } 787 788 /* 789 * Can this new request be merged in front of next? 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 if (prev && addr < prev->vm_end) /* case 4 */ 796 vma_adjust(prev, prev->vm_start, 797 addr, prev->vm_pgoff, NULL); 798 else /* cases 3, 8 */ 799 vma_adjust(area, addr, next->vm_end, 800 next->vm_pgoff - pglen, NULL); 801 return area; 802 } 803 804 return NULL; 805} 806 807/* 808 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 809 * neighbouring vmas for a suitable anon_vma, before it goes off 810 * to allocate a new anon_vma. It checks because a repetitive 811 * sequence of mprotects and faults may otherwise lead to distinct 812 * anon_vmas being allocated, preventing vma merge in subsequent 813 * mprotect. 814 */ 815struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 816{ 817 struct vm_area_struct *near; 818 unsigned long vm_flags; 819 820 near = vma->vm_next; 821 if (!near) 822 goto try_prev; 823 824 /* 825 * Since only mprotect tries to remerge vmas, match flags 826 * which might be mprotected into each other later on. 827 * Neither mlock nor madvise tries to remerge at present, 828 * so leave their flags as obstructing a merge. 829 */ 830 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 831 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 832 833 if (near->anon_vma && vma->vm_end == near->vm_start && 834 mpol_equal(vma_policy(vma), vma_policy(near)) && 835 can_vma_merge_before(near, vm_flags, 836 NULL, vma->vm_file, vma->vm_pgoff + 837 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 838 return near->anon_vma; 839try_prev: 840 /* 841 * It is potentially slow to have to call find_vma_prev here. 842 * But it's only on the first write fault on the vma, not 843 * every time, and we could devise a way to avoid it later 844 * (e.g. stash info in next's anon_vma_node when assigning 845 * an anon_vma, or when trying vma_merge). Another time. 846 */ 847 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 848 if (!near) 849 goto none; 850 851 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 852 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 853 854 if (near->anon_vma && near->vm_end == vma->vm_start && 855 mpol_equal(vma_policy(near), vma_policy(vma)) && 856 can_vma_merge_after(near, vm_flags, 857 NULL, vma->vm_file, vma->vm_pgoff)) 858 return near->anon_vma; 859none: 860 /* 861 * There's no absolute need to look only at touching neighbours: 862 * we could search further afield for "compatible" anon_vmas. 863 * But it would probably just be a waste of time searching, 864 * or lead to too many vmas hanging off the same anon_vma. 865 * We're trying to allow mprotect remerging later on, 866 * not trying to minimize memory used for anon_vmas. 867 */ 868 return NULL; 869} 870 871#ifdef CONFIG_PROC_FS 872void vm_stat_account(struct mm_struct *mm, unsigned long flags, 873 struct file *file, long pages) 874{ 875 const unsigned long stack_flags 876 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 877 878 if (file) { 879 mm->shared_vm += pages; 880 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 881 mm->exec_vm += pages; 882 } else if (flags & stack_flags) 883 mm->stack_vm += pages; 884 if (flags & (VM_RESERVED|VM_IO)) 885 mm->reserved_vm += pages; 886} 887#endif /* CONFIG_PROC_FS */ 888 889/* 890 * The caller must hold down_write(current->mm->mmap_sem). 891 */ 892 893unsigned long do_mmap_pgoff(struct file * file, unsigned long addr, 894 unsigned long len, unsigned long prot, 895 unsigned long flags, unsigned long pgoff) 896{ 897 struct mm_struct * mm = current->mm; 898 struct inode *inode; 899 unsigned int vm_flags; 900 int error; 901 int accountable = 1; 902 unsigned long reqprot = prot; 903 904 /* 905 * Does the application expect PROT_READ to imply PROT_EXEC? 906 * 907 * (the exception is when the underlying filesystem is noexec 908 * mounted, in which case we dont add PROT_EXEC.) 909 */ 910 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 911 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 912 prot |= PROT_EXEC; 913 914 if (!len) 915 return -EINVAL; 916 917 error = arch_mmap_check(addr, len, flags); 918 if (error) 919 return error; 920 921 /* Careful about overflows.. */ 922 len = PAGE_ALIGN(len); 923 if (!len || len > TASK_SIZE) 924 return -ENOMEM; 925 926 /* offset overflow? */ 927 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 928 return -EOVERFLOW; 929 930 /* Too many mappings? */ 931 if (mm->map_count > sysctl_max_map_count) 932 return -ENOMEM; 933 934 /* Obtain the address to map to. we verify (or select) it and ensure 935 * that it represents a valid section of the address space. 936 */ 937 addr = get_unmapped_area(file, addr, len, pgoff, flags); 938 if (addr & ~PAGE_MASK) 939 return addr; 940 941 /* Do simple checking here so the lower-level routines won't have 942 * to. we assume access permissions have been handled by the open 943 * of the memory object, so we don't do any here. 944 */ 945 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 946 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 947 948 if (flags & MAP_LOCKED) { 949 if (!can_do_mlock()) 950 return -EPERM; 951 vm_flags |= VM_LOCKED; 952 } 953 /* mlock MCL_FUTURE? */ 954 if (vm_flags & VM_LOCKED) { 955 unsigned long locked, lock_limit; 956 locked = len >> PAGE_SHIFT; 957 locked += mm->locked_vm; 958 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 959 lock_limit >>= PAGE_SHIFT; 960 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 961 return -EAGAIN; 962 } 963 964 inode = file ? file->f_path.dentry->d_inode : NULL; 965 966 if (file) { 967 switch (flags & MAP_TYPE) { 968 case MAP_SHARED: 969 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 970 return -EACCES; 971 972 /* 973 * Make sure we don't allow writing to an append-only 974 * file.. 975 */ 976 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 977 return -EACCES; 978 979 /* 980 * Make sure there are no mandatory locks on the file. 981 */ 982 if (locks_verify_locked(inode)) 983 return -EAGAIN; 984 985 vm_flags |= VM_SHARED | VM_MAYSHARE; 986 if (!(file->f_mode & FMODE_WRITE)) 987 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 988 989 /* fall through */ 990 case MAP_PRIVATE: 991 if (!(file->f_mode & FMODE_READ)) 992 return -EACCES; 993 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 994 if (vm_flags & VM_EXEC) 995 return -EPERM; 996 vm_flags &= ~VM_MAYEXEC; 997 } 998 if (is_file_hugepages(file)) 999 accountable = 0; 1000 1001 if (!file->f_op || !file->f_op->mmap) 1002 return -ENODEV; 1003 break; 1004 1005 default: 1006 return -EINVAL; 1007 } 1008 } else { 1009 switch (flags & MAP_TYPE) { 1010 case MAP_SHARED: 1011 vm_flags |= VM_SHARED | VM_MAYSHARE; 1012 break; 1013 case MAP_PRIVATE: 1014 /* 1015 * Set pgoff according to addr for anon_vma. 1016 */ 1017 pgoff = addr >> PAGE_SHIFT; 1018 break; 1019 default: 1020 return -EINVAL; 1021 } 1022 } 1023 1024 error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1025 if (error) 1026 return error; 1027 1028 return mmap_region(file, addr, len, flags, vm_flags, pgoff, 1029 accountable); 1030} 1031EXPORT_SYMBOL(do_mmap_pgoff); 1032 1033/* 1034 * Some shared mappigns will want the pages marked read-only 1035 * to track write events. If so, we'll downgrade vm_page_prot 1036 * to the private version (using protection_map[] without the 1037 * VM_SHARED bit). 1038 */ 1039int vma_wants_writenotify(struct vm_area_struct *vma) 1040{ 1041 unsigned int vm_flags = vma->vm_flags; 1042 1043 /* If it was private or non-writable, the write bit is already clear */ 1044 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1045 return 0; 1046 1047 /* The backer wishes to know when pages are first written to? */ 1048 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1049 return 1; 1050 1051 /* The open routine did something to the protections already? */ 1052 if (pgprot_val(vma->vm_page_prot) != 1053 pgprot_val(protection_map[vm_flags & 1054 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)])) 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 = protection_map[vm_flags & 1136 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; 1137 vma->vm_pgoff = pgoff; 1138 1139 if (file) { 1140 error = -EINVAL; 1141 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1142 goto free_vma; 1143 if (vm_flags & VM_DENYWRITE) { 1144 error = deny_write_access(file); 1145 if (error) 1146 goto free_vma; 1147 correct_wcount = 1; 1148 } 1149 vma->vm_file = file; 1150 get_file(file); 1151 error = file->f_op->mmap(file, vma); 1152 if (error) 1153 goto unmap_and_free_vma; 1154 } else if (vm_flags & VM_SHARED) { 1155 error = shmem_zero_setup(vma); 1156 if (error) 1157 goto free_vma; 1158 } 1159 1160 /* We set VM_ACCOUNT in a shared mapping's vm_flags, to inform 1161 * shmem_zero_setup (perhaps called through /dev/zero's ->mmap) 1162 * that memory reservation must be checked; but that reservation 1163 * belongs to shared memory object, not to vma: so now clear it. 1164 */ 1165 if ((vm_flags & (VM_SHARED|VM_ACCOUNT)) == (VM_SHARED|VM_ACCOUNT)) 1166 vma->vm_flags &= ~VM_ACCOUNT; 1167 1168 /* Can addr have changed?? 1169 * 1170 * Answer: Yes, several device drivers can do it in their 1171 * f_op->mmap method. -DaveM 1172 */ 1173 addr = vma->vm_start; 1174 pgoff = vma->vm_pgoff; 1175 vm_flags = vma->vm_flags; 1176 1177 if (vma_wants_writenotify(vma)) 1178 vma->vm_page_prot = 1179 protection_map[vm_flags & (VM_READ|VM_WRITE|VM_EXEC)]; 1180 1181 if (!file || !vma_merge(mm, prev, addr, vma->vm_end, 1182 vma->vm_flags, NULL, file, pgoff, vma_policy(vma))) { 1183 file = vma->vm_file; 1184 vma_link(mm, vma, prev, rb_link, rb_parent); 1185 if (correct_wcount) 1186 atomic_inc(&inode->i_writecount); 1187 } else { 1188 if (file) { 1189 if (correct_wcount) 1190 atomic_inc(&inode->i_writecount); 1191 fput(file); 1192 } 1193 mpol_free(vma_policy(vma)); 1194 kmem_cache_free(vm_area_cachep, vma); 1195 } 1196out: 1197 mm->total_vm += len >> PAGE_SHIFT; 1198 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1199 if (vm_flags & VM_LOCKED) { 1200 mm->locked_vm += len >> PAGE_SHIFT; 1201 make_pages_present(addr, addr + len); 1202 } 1203 if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) 1204 make_pages_present(addr, addr + len); 1205 return addr; 1206 1207unmap_and_free_vma: 1208 if (correct_wcount) 1209 atomic_inc(&inode->i_writecount); 1210 vma->vm_file = NULL; 1211 fput(file); 1212 1213 /* Undo any partial mapping done by a device driver. */ 1214 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1215 charged = 0; 1216free_vma: 1217 kmem_cache_free(vm_area_cachep, vma); 1218unacct_error: 1219 if (charged) 1220 vm_unacct_memory(charged); 1221 return error; 1222} 1223 1224/* Get an address range which is currently unmapped. 1225 * For shmat() with addr=0. 1226 * 1227 * Ugly calling convention alert: 1228 * Return value with the low bits set means error value, 1229 * ie 1230 * if (ret & ~PAGE_MASK) 1231 * error = ret; 1232 * 1233 * This function "knows" that -ENOMEM has the bits set. 1234 */ 1235#ifndef HAVE_ARCH_UNMAPPED_AREA 1236unsigned long 1237arch_get_unmapped_area(struct file *filp, unsigned long addr, 1238 unsigned long len, unsigned long pgoff, unsigned long flags) 1239{ 1240 struct mm_struct *mm = current->mm; 1241 struct vm_area_struct *vma; 1242 unsigned long start_addr; 1243 1244 if (len > TASK_SIZE) 1245 return -ENOMEM; 1246 1247 if (flags & MAP_FIXED) 1248 return addr; 1249 1250 if (addr) { 1251 addr = PAGE_ALIGN(addr); 1252 vma = find_vma(mm, addr); 1253 if (TASK_SIZE - len >= addr && 1254 (!vma || addr + len <= vma->vm_start)) 1255 return addr; 1256 } 1257 if (len > mm->cached_hole_size) { 1258 start_addr = addr = mm->free_area_cache; 1259 } else { 1260 start_addr = addr = TASK_UNMAPPED_BASE; 1261 mm->cached_hole_size = 0; 1262 } 1263 1264full_search: 1265 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1266 /* At this point: (!vma || addr < vma->vm_end). */ 1267 if (TASK_SIZE - len < addr) { 1268 /* 1269 * Start a new search - just in case we missed 1270 * some holes. 1271 */ 1272 if (start_addr != TASK_UNMAPPED_BASE) { 1273 addr = TASK_UNMAPPED_BASE; 1274 start_addr = addr; 1275 mm->cached_hole_size = 0; 1276 goto full_search; 1277 } 1278 return -ENOMEM; 1279 } 1280 if (!vma || addr + len <= vma->vm_start) { 1281 /* 1282 * Remember the place where we stopped the search: 1283 */ 1284 mm->free_area_cache = addr + len; 1285 return addr; 1286 } 1287 if (addr + mm->cached_hole_size < vma->vm_start) 1288 mm->cached_hole_size = vma->vm_start - addr; 1289 addr = vma->vm_end; 1290 } 1291} 1292#endif 1293 1294void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1295{ 1296 /* 1297 * Is this a new hole at the lowest possible address? 1298 */ 1299 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1300 mm->free_area_cache = addr; 1301 mm->cached_hole_size = ~0UL; 1302 } 1303} 1304 1305/* 1306 * This mmap-allocator allocates new areas top-down from below the 1307 * stack's low limit (the base): 1308 */ 1309#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1310unsigned long 1311arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1312 const unsigned long len, const unsigned long pgoff, 1313 const unsigned long flags) 1314{ 1315 struct vm_area_struct *vma; 1316 struct mm_struct *mm = current->mm; 1317 unsigned long addr = addr0; 1318 1319 /* requested length too big for entire address space */ 1320 if (len > TASK_SIZE) 1321 return -ENOMEM; 1322 1323 if (flags & MAP_FIXED) 1324 return addr; 1325 1326 /* requesting a specific address */ 1327 if (addr) { 1328 addr = PAGE_ALIGN(addr); 1329 vma = find_vma(mm, addr); 1330 if (TASK_SIZE - len >= addr && 1331 (!vma || addr + len <= vma->vm_start)) 1332 return addr; 1333 } 1334 1335 /* check if free_area_cache is useful for us */ 1336 if (len <= mm->cached_hole_size) { 1337 mm->cached_hole_size = 0; 1338 mm->free_area_cache = mm->mmap_base; 1339 } 1340 1341 /* either no address requested or can't fit in requested address hole */ 1342 addr = mm->free_area_cache; 1343 1344 /* make sure it can fit in the remaining address space */ 1345 if (addr > len) { 1346 vma = find_vma(mm, addr-len); 1347 if (!vma || addr <= vma->vm_start) 1348 /* remember the address as a hint for next time */ 1349 return (mm->free_area_cache = addr-len); 1350 } 1351 1352 if (mm->mmap_base < len) 1353 goto bottomup; 1354 1355 addr = mm->mmap_base-len; 1356 1357 do { 1358 /* 1359 * Lookup failure means no vma is above this address, 1360 * else if new region fits below vma->vm_start, 1361 * return with success: 1362 */ 1363 vma = find_vma(mm, addr); 1364 if (!vma || addr+len <= vma->vm_start) 1365 /* remember the address as a hint for next time */ 1366 return (mm->free_area_cache = addr); 1367 1368 /* remember the largest hole we saw so far */ 1369 if (addr + mm->cached_hole_size < vma->vm_start) 1370 mm->cached_hole_size = vma->vm_start - addr; 1371 1372 /* try just below the current vma->vm_start */ 1373 addr = vma->vm_start-len; 1374 } while (len < vma->vm_start); 1375 1376bottomup: 1377 /* 1378 * A failed mmap() very likely causes application failure, 1379 * so fall back to the bottom-up function here. This scenario 1380 * can happen with large stack limits and large mmap() 1381 * allocations. 1382 */ 1383 mm->cached_hole_size = ~0UL; 1384 mm->free_area_cache = TASK_UNMAPPED_BASE; 1385 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1386 /* 1387 * Restore the topdown base: 1388 */ 1389 mm->free_area_cache = mm->mmap_base; 1390 mm->cached_hole_size = ~0UL; 1391 1392 return addr; 1393} 1394#endif 1395 1396void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1397{ 1398 /* 1399 * Is this a new hole at the highest possible address? 1400 */ 1401 if (addr > mm->free_area_cache) 1402 mm->free_area_cache = addr; 1403 1404 /* dont allow allocations above current base */ 1405 if (mm->free_area_cache > mm->mmap_base) 1406 mm->free_area_cache = mm->mmap_base; 1407} 1408 1409unsigned long 1410get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1411 unsigned long pgoff, unsigned long flags) 1412{ 1413 unsigned long (*get_area)(struct file *, unsigned long, 1414 unsigned long, unsigned long, unsigned long); 1415 1416 get_area = current->mm->get_unmapped_area; 1417 if (file && file->f_op && file->f_op->get_unmapped_area) 1418 get_area = file->f_op->get_unmapped_area; 1419 addr = get_area(file, addr, len, pgoff, flags); 1420 if (IS_ERR_VALUE(addr)) 1421 return addr; 1422 1423 if (addr > TASK_SIZE - len) 1424 return -ENOMEM; 1425 if (addr & ~PAGE_MASK) 1426 return -EINVAL; 1427 1428 return addr; 1429} 1430 1431EXPORT_SYMBOL(get_unmapped_area); 1432 1433/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1434struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr) 1435{ 1436 struct vm_area_struct *vma = NULL; 1437 1438 if (mm) { 1439 /* Check the cache first. */ 1440 /* (Cache hit rate is typically around 35%.) */ 1441 vma = mm->mmap_cache; 1442 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1443 struct rb_node * rb_node; 1444 1445 rb_node = mm->mm_rb.rb_node; 1446 vma = NULL; 1447 1448 while (rb_node) { 1449 struct vm_area_struct * vma_tmp; 1450 1451 vma_tmp = rb_entry(rb_node, 1452 struct vm_area_struct, vm_rb); 1453 1454 if (vma_tmp->vm_end > addr) { 1455 vma = vma_tmp; 1456 if (vma_tmp->vm_start <= addr) 1457 break; 1458 rb_node = rb_node->rb_left; 1459 } else 1460 rb_node = rb_node->rb_right; 1461 } 1462 if (vma) 1463 mm->mmap_cache = vma; 1464 } 1465 } 1466 return vma; 1467} 1468 1469EXPORT_SYMBOL(find_vma); 1470 1471/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1472struct vm_area_struct * 1473find_vma_prev(struct mm_struct *mm, unsigned long addr, 1474 struct vm_area_struct **pprev) 1475{ 1476 struct vm_area_struct *vma = NULL, *prev = NULL; 1477 struct rb_node * rb_node; 1478 if (!mm) 1479 goto out; 1480 1481 /* Guard against addr being lower than the first VMA */ 1482 vma = mm->mmap; 1483 1484 /* Go through the RB tree quickly. */ 1485 rb_node = mm->mm_rb.rb_node; 1486 1487 while (rb_node) { 1488 struct vm_area_struct *vma_tmp; 1489 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1490 1491 if (addr < vma_tmp->vm_end) { 1492 rb_node = rb_node->rb_left; 1493 } else { 1494 prev = vma_tmp; 1495 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1496 break; 1497 rb_node = rb_node->rb_right; 1498 } 1499 } 1500 1501out: 1502 *pprev = prev; 1503 return prev ? prev->vm_next : vma; 1504} 1505 1506/* 1507 * Verify that the stack growth is acceptable and 1508 * update accounting. This is shared with both the 1509 * grow-up and grow-down cases. 1510 */ 1511static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, unsigned long grow) 1512{ 1513 struct mm_struct *mm = vma->vm_mm; 1514 struct rlimit *rlim = current->signal->rlim; 1515 unsigned long new_start; 1516 1517 /* address space limit tests */ 1518 if (!may_expand_vm(mm, grow)) 1519 return -ENOMEM; 1520 1521 /* Stack limit test */ 1522 if (size > rlim[RLIMIT_STACK].rlim_cur) 1523 return -ENOMEM; 1524 1525 /* mlock limit tests */ 1526 if (vma->vm_flags & VM_LOCKED) { 1527 unsigned long locked; 1528 unsigned long limit; 1529 locked = mm->locked_vm + grow; 1530 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1531 if (locked > limit && !capable(CAP_IPC_LOCK)) 1532 return -ENOMEM; 1533 } 1534 1535 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1536 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1537 vma->vm_end - size; 1538 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1539 return -EFAULT; 1540 1541 /* 1542 * Overcommit.. This must be the final test, as it will 1543 * update security statistics. 1544 */ 1545 if (security_vm_enough_memory(grow)) 1546 return -ENOMEM; 1547 1548 /* Ok, everything looks good - let it rip */ 1549 mm->total_vm += grow; 1550 if (vma->vm_flags & VM_LOCKED) 1551 mm->locked_vm += grow; 1552 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1553 return 0; 1554} 1555 1556#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1557/* 1558 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1559 * vma is the last one with address > vma->vm_end. Have to extend vma. 1560 */ 1561#ifndef CONFIG_IA64 1562static inline 1563#endif 1564int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1565{ 1566 int error; 1567 1568 if (!(vma->vm_flags & VM_GROWSUP)) 1569 return -EFAULT; 1570 1571 /* 1572 * We must make sure the anon_vma is allocated 1573 * so that the anon_vma locking is not a noop. 1574 */ 1575 if (unlikely(anon_vma_prepare(vma))) 1576 return -ENOMEM; 1577 anon_vma_lock(vma); 1578 1579 /* 1580 * vma->vm_start/vm_end cannot change under us because the caller 1581 * is required to hold the mmap_sem in read mode. We need the 1582 * anon_vma lock to serialize against concurrent expand_stacks. 1583 * Also guard against wrapping around to address 0. 1584 */ 1585 if (address < PAGE_ALIGN(address+4)) 1586 address = PAGE_ALIGN(address+4); 1587 else { 1588 anon_vma_unlock(vma); 1589 return -ENOMEM; 1590 } 1591 error = 0; 1592 1593 /* Somebody else might have raced and expanded it already */ 1594 if (address > vma->vm_end) { 1595 unsigned long size, grow; 1596 1597 size = address - vma->vm_start; 1598 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1599 1600 error = acct_stack_growth(vma, size, grow); 1601 if (!error) 1602 vma->vm_end = address; 1603 } 1604 anon_vma_unlock(vma); 1605 return error; 1606} 1607#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1608 1609/* 1610 * vma is the first one with address < vma->vm_start. Have to extend vma. 1611 */ 1612static inline int expand_downwards(struct vm_area_struct *vma, 1613 unsigned long address) 1614{ 1615 int error; 1616 1617 /* 1618 * We must make sure the anon_vma is allocated 1619 * so that the anon_vma locking is not a noop. 1620 */ 1621 if (unlikely(anon_vma_prepare(vma))) 1622 return -ENOMEM; 1623 anon_vma_lock(vma); 1624 1625 /* 1626 * vma->vm_start/vm_end cannot change under us because the caller 1627 * is required to hold the mmap_sem in read mode. We need the 1628 * anon_vma lock to serialize against concurrent expand_stacks. 1629 */ 1630 address &= PAGE_MASK; 1631 error = 0; 1632 1633 /* Somebody else might have raced and expanded it already */ 1634 if (address < vma->vm_start) { 1635 unsigned long size, grow; 1636 1637 size = vma->vm_end - address; 1638 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1639 1640 error = acct_stack_growth(vma, size, grow); 1641 if (!error) { 1642 vma->vm_start = address; 1643 vma->vm_pgoff -= grow; 1644 } 1645 } 1646 anon_vma_unlock(vma); 1647 return error; 1648} 1649 1650int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) 1651{ 1652 return expand_downwards(vma, address); 1653} 1654 1655#ifdef CONFIG_STACK_GROWSUP 1656int expand_stack(struct vm_area_struct *vma, unsigned long address) 1657{ 1658 return expand_upwards(vma, address); 1659} 1660 1661struct vm_area_struct * 1662find_extend_vma(struct mm_struct *mm, unsigned long addr) 1663{ 1664 struct vm_area_struct *vma, *prev; 1665 1666 addr &= PAGE_MASK; 1667 vma = find_vma_prev(mm, addr, &prev); 1668 if (vma && (vma->vm_start <= addr)) 1669 return vma; 1670 if (!prev || expand_stack(prev, addr)) 1671 return NULL; 1672 if (prev->vm_flags & VM_LOCKED) 1673 make_pages_present(addr, prev->vm_end); 1674 return prev; 1675} 1676#else 1677int expand_stack(struct vm_area_struct *vma, unsigned long address) 1678{ 1679 return expand_downwards(vma, address); 1680} 1681 1682struct vm_area_struct * 1683find_extend_vma(struct mm_struct * mm, unsigned long addr) 1684{ 1685 struct vm_area_struct * vma; 1686 unsigned long start; 1687 1688 addr &= PAGE_MASK; 1689 vma = find_vma(mm,addr); 1690 if (!vma) 1691 return NULL; 1692 if (vma->vm_start <= addr) 1693 return vma; 1694 if (!(vma->vm_flags & VM_GROWSDOWN)) 1695 return NULL; 1696 start = vma->vm_start; 1697 if (expand_stack(vma, addr)) 1698 return NULL; 1699 if (vma->vm_flags & VM_LOCKED) 1700 make_pages_present(addr, start); 1701 return vma; 1702} 1703#endif 1704 1705/* 1706 * Ok - we have the memory areas we should free on the vma list, 1707 * so release them, and do the vma updates. 1708 * 1709 * Called with the mm semaphore held. 1710 */ 1711static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1712{ 1713 /* Update high watermark before we lower total_vm */ 1714 update_hiwater_vm(mm); 1715 do { 1716 long nrpages = vma_pages(vma); 1717 1718 mm->total_vm -= nrpages; 1719 if (vma->vm_flags & VM_LOCKED) 1720 mm->locked_vm -= nrpages; 1721 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1722 vma = remove_vma(vma); 1723 } while (vma); 1724 validate_mm(mm); 1725} 1726 1727/* 1728 * Get rid of page table information in the indicated region. 1729 * 1730 * Called with the mm semaphore held. 1731 */ 1732static void unmap_region(struct mm_struct *mm, 1733 struct vm_area_struct *vma, struct vm_area_struct *prev, 1734 unsigned long start, unsigned long end) 1735{ 1736 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1737 struct mmu_gather *tlb; 1738 unsigned long nr_accounted = 0; 1739 1740 lru_add_drain(); 1741 tlb = tlb_gather_mmu(mm, 0); 1742 update_hiwater_rss(mm); 1743 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1744 vm_unacct_memory(nr_accounted); 1745 free_pgtables(&tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1746 next? next->vm_start: 0); 1747 tlb_finish_mmu(tlb, start, end); 1748} 1749 1750/* 1751 * Create a list of vma's touched by the unmap, removing them from the mm's 1752 * vma list as we go.. 1753 */ 1754static void 1755detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1756 struct vm_area_struct *prev, unsigned long end) 1757{ 1758 struct vm_area_struct **insertion_point; 1759 struct vm_area_struct *tail_vma = NULL; 1760 unsigned long addr; 1761 1762 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1763 do { 1764 rb_erase(&vma->vm_rb, &mm->mm_rb); 1765 mm->map_count--; 1766 tail_vma = vma; 1767 vma = vma->vm_next; 1768 } while (vma && vma->vm_start < end); 1769 *insertion_point = vma; 1770 tail_vma->vm_next = NULL; 1771 if (mm->unmap_area == arch_unmap_area) 1772 addr = prev ? prev->vm_end : mm->mmap_base; 1773 else 1774 addr = vma ? vma->vm_start : mm->mmap_base; 1775 mm->unmap_area(mm, addr); 1776 mm->mmap_cache = NULL; /* Kill the cache. */ 1777} 1778 1779/* 1780 * Split a vma into two pieces at address 'addr', a new vma is allocated 1781 * either for the first part or the tail. 1782 */ 1783int split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1784 unsigned long addr, int new_below) 1785{ 1786 struct mempolicy *pol; 1787 struct vm_area_struct *new; 1788 1789 if (is_vm_hugetlb_page(vma) && (addr & ~HPAGE_MASK)) 1790 return -EINVAL; 1791 1792 if (mm->map_count >= sysctl_max_map_count) 1793 return -ENOMEM; 1794 1795 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1796 if (!new) 1797 return -ENOMEM; 1798 1799 /* most fields are the same, copy all, and then fixup */ 1800 *new = *vma; 1801 1802 if (new_below) 1803 new->vm_end = addr; 1804 else { 1805 new->vm_start = addr; 1806 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1807 } 1808 1809 pol = mpol_copy(vma_policy(vma)); 1810 if (IS_ERR(pol)) { 1811 kmem_cache_free(vm_area_cachep, new); 1812 return PTR_ERR(pol); 1813 } 1814 vma_set_policy(new, pol); 1815 1816 if (new->vm_file) 1817 get_file(new->vm_file); 1818 1819 if (new->vm_ops && new->vm_ops->open) 1820 new->vm_ops->open(new); 1821 1822 if (new_below) 1823 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1824 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1825 else 1826 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1827 1828 return 0; 1829} 1830 1831/* Munmap is split into 2 main parts -- this part which finds 1832 * what needs doing, and the areas themselves, which do the 1833 * work. This now handles partial unmappings. 1834 * Jeremy Fitzhardinge <jeremy@goop.org> 1835 */ 1836int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1837{ 1838 unsigned long end; 1839 struct vm_area_struct *vma, *prev, *last; 1840 1841 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1842 return -EINVAL; 1843 1844 if ((len = PAGE_ALIGN(len)) == 0) 1845 return -EINVAL; 1846 1847 /* Find the first overlapping VMA */ 1848 vma = find_vma_prev(mm, start, &prev); 1849 if (!vma) 1850 return 0; 1851 /* we have start < vma->vm_end */ 1852 1853 /* if it doesn't overlap, we have nothing.. */ 1854 end = start + len; 1855 if (vma->vm_start >= end) 1856 return 0; 1857 1858 /* 1859 * If we need to split any vma, do it now to save pain later. 1860 * 1861 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1862 * unmapped vm_area_struct will remain in use: so lower split_vma 1863 * places tmp vma above, and higher split_vma places tmp vma below. 1864 */ 1865 if (start > vma->vm_start) { 1866 int error = split_vma(mm, vma, start, 0); 1867 if (error) 1868 return error; 1869 prev = vma; 1870 } 1871 1872 /* Does it split the last one? */ 1873 last = find_vma(mm, end); 1874 if (last && end > last->vm_start) { 1875 int error = split_vma(mm, last, end, 1); 1876 if (error) 1877 return error; 1878 } 1879 vma = prev? prev->vm_next: mm->mmap; 1880 1881 /* 1882 * Remove the vma's, and unmap the actual pages 1883 */ 1884 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1885 unmap_region(mm, vma, prev, start, end); 1886 1887 /* Fix up all other VM information */ 1888 remove_vma_list(mm, vma); 1889 1890 return 0; 1891} 1892 1893EXPORT_SYMBOL(do_munmap); 1894 1895asmlinkage long sys_munmap(unsigned long addr, size_t len) 1896{ 1897 int ret; 1898 struct mm_struct *mm = current->mm; 1899 1900 profile_munmap(addr); 1901 1902 down_write(&mm->mmap_sem); 1903 ret = do_munmap(mm, addr, len); 1904 up_write(&mm->mmap_sem); 1905 return ret; 1906} 1907 1908static inline void verify_mm_writelocked(struct mm_struct *mm) 1909{ 1910#ifdef CONFIG_DEBUG_VM 1911 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1912 WARN_ON(1); 1913 up_read(&mm->mmap_sem); 1914 } 1915#endif 1916} 1917 1918/* 1919 * this is really a simplified "do_mmap". it only handles 1920 * anonymous maps. eventually we may be able to do some 1921 * brk-specific accounting here. 1922 */ 1923unsigned long do_brk(unsigned long addr, unsigned long len) 1924{ 1925 struct mm_struct * mm = current->mm; 1926 struct vm_area_struct * vma, * prev; 1927 unsigned long flags; 1928 struct rb_node ** rb_link, * rb_parent; 1929 pgoff_t pgoff = addr >> PAGE_SHIFT; 1930 int error; 1931 1932 len = PAGE_ALIGN(len); 1933 if (!len) 1934 return addr; 1935 1936 if ((addr + len) > TASK_SIZE || (addr + len) < addr) 1937 return -EINVAL; 1938 1939 if (is_hugepage_only_range(mm, addr, len)) 1940 return -EINVAL; 1941 1942 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 1943 1944 error = arch_mmap_check(addr, len, flags); 1945 if (error) 1946 return error; 1947 1948 /* 1949 * mlock MCL_FUTURE? 1950 */ 1951 if (mm->def_flags & VM_LOCKED) { 1952 unsigned long locked, lock_limit; 1953 locked = len >> PAGE_SHIFT; 1954 locked += mm->locked_vm; 1955 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 1956 lock_limit >>= PAGE_SHIFT; 1957 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1958 return -EAGAIN; 1959 } 1960 1961 /* 1962 * mm->mmap_sem is required to protect against another thread 1963 * changing the mappings in case we sleep. 1964 */ 1965 verify_mm_writelocked(mm); 1966 1967 /* 1968 * Clear old maps. this also does some error checking for us 1969 */ 1970 munmap_back: 1971 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1972 if (vma && vma->vm_start < addr + len) { 1973 if (do_munmap(mm, addr, len)) 1974 return -ENOMEM; 1975 goto munmap_back; 1976 } 1977 1978 /* Check against address space limits *after* clearing old maps... */ 1979 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1980 return -ENOMEM; 1981 1982 if (mm->map_count > sysctl_max_map_count) 1983 return -ENOMEM; 1984 1985 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 1986 return -ENOMEM; 1987 1988 /* Can we just expand an old private anonymous mapping? */ 1989 if (vma_merge(mm, prev, addr, addr + len, flags, 1990 NULL, NULL, pgoff, NULL)) 1991 goto out; 1992 1993 /* 1994 * create a vma struct for an anonymous mapping 1995 */ 1996 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1997 if (!vma) { 1998 vm_unacct_memory(len >> PAGE_SHIFT); 1999 return -ENOMEM; 2000 } 2001 2002 vma->vm_mm = mm; 2003 vma->vm_start = addr; 2004 vma->vm_end = addr + len; 2005 vma->vm_pgoff = pgoff; 2006 vma->vm_flags = flags; 2007 vma->vm_page_prot = protection_map[flags & 2008 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]; 2009 vma_link(mm, vma, prev, rb_link, rb_parent); 2010out: 2011 mm->total_vm += len >> PAGE_SHIFT; 2012 if (flags & VM_LOCKED) { 2013 mm->locked_vm += len >> PAGE_SHIFT; 2014 make_pages_present(addr, addr + len); 2015 } 2016 return addr; 2017} 2018 2019EXPORT_SYMBOL(do_brk); 2020 2021/* Release all mmaps. */ 2022void exit_mmap(struct mm_struct *mm) 2023{ 2024 struct mmu_gather *tlb; 2025 struct vm_area_struct *vma = mm->mmap; 2026 unsigned long nr_accounted = 0; 2027 unsigned long end; 2028 2029 /* mm's last user has gone, and its about to be pulled down */ 2030 arch_exit_mmap(mm); 2031 2032 lru_add_drain(); 2033 flush_cache_mm(mm); 2034 tlb = tlb_gather_mmu(mm, 1); 2035 /* Don't update_hiwater_rss(mm) here, do_exit already did */ 2036 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2037 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 2038 vm_unacct_memory(nr_accounted); 2039 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); 2040 tlb_finish_mmu(tlb, 0, end); 2041 2042 /* 2043 * Walk the list again, actually closing and freeing it, 2044 * with preemption enabled, without holding any MM locks. 2045 */ 2046 while (vma) 2047 vma = remove_vma(vma); 2048 2049 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2050} 2051 2052/* Insert vm structure into process list sorted by address 2053 * and into the inode's i_mmap tree. If vm_file is non-NULL 2054 * then i_mmap_lock is taken here. 2055 */ 2056int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 2057{ 2058 struct vm_area_struct * __vma, * prev; 2059 struct rb_node ** rb_link, * rb_parent; 2060 2061 /* 2062 * The vm_pgoff of a purely anonymous vma should be irrelevant 2063 * until its first write fault, when page's anon_vma and index 2064 * are set. But now set the vm_pgoff it will almost certainly 2065 * end up with (unless mremap moves it elsewhere before that 2066 * first wfault), so /proc/pid/maps tells a consistent story. 2067 * 2068 * By setting it to reflect the virtual start address of the 2069 * vma, merges and splits can happen in a seamless way, just 2070 * using the existing file pgoff checks and manipulations. 2071 * Similarly in do_mmap_pgoff and in do_brk. 2072 */ 2073 if (!vma->vm_file) { 2074 BUG_ON(vma->anon_vma); 2075 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2076 } 2077 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2078 if (__vma && __vma->vm_start < vma->vm_end) 2079 return -ENOMEM; 2080 if ((vma->vm_flags & VM_ACCOUNT) && 2081 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2082 return -ENOMEM; 2083 vma_link(mm, vma, prev, rb_link, rb_parent); 2084 return 0; 2085} 2086 2087/* 2088 * Copy the vma structure to a new location in the same mm, 2089 * prior to moving page table entries, to effect an mremap move. 2090 */ 2091struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2092 unsigned long addr, unsigned long len, pgoff_t pgoff) 2093{ 2094 struct vm_area_struct *vma = *vmap; 2095 unsigned long vma_start = vma->vm_start; 2096 struct mm_struct *mm = vma->vm_mm; 2097 struct vm_area_struct *new_vma, *prev; 2098 struct rb_node **rb_link, *rb_parent; 2099 struct mempolicy *pol; 2100 2101 /* 2102 * If anonymous vma has not yet been faulted, update new pgoff 2103 * to match new location, to increase its chance of merging. 2104 */ 2105 if (!vma->vm_file && !vma->anon_vma) 2106 pgoff = addr >> PAGE_SHIFT; 2107 2108 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2109 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2110 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2111 if (new_vma) { 2112 /* 2113 * Source vma may have been merged into new_vma 2114 */ 2115 if (vma_start >= new_vma->vm_start && 2116 vma_start < new_vma->vm_end) 2117 *vmap = new_vma; 2118 } else { 2119 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2120 if (new_vma) { 2121 *new_vma = *vma; 2122 pol = mpol_copy(vma_policy(vma)); 2123 if (IS_ERR(pol)) { 2124 kmem_cache_free(vm_area_cachep, new_vma); 2125 return NULL; 2126 } 2127 vma_set_policy(new_vma, pol); 2128 new_vma->vm_start = addr; 2129 new_vma->vm_end = addr + len; 2130 new_vma->vm_pgoff = pgoff; 2131 if (new_vma->vm_file) 2132 get_file(new_vma->vm_file); 2133 if (new_vma->vm_ops && new_vma->vm_ops->open) 2134 new_vma->vm_ops->open(new_vma); 2135 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2136 } 2137 } 2138 return new_vma; 2139} 2140 2141/* 2142 * Return true if the calling process may expand its vm space by the passed 2143 * number of pages 2144 */ 2145int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2146{ 2147 unsigned long cur = mm->total_vm; /* pages */ 2148 unsigned long lim; 2149 2150 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2151 2152 if (cur + npages > lim) 2153 return 0; 2154 return 1; 2155} 2156 2157 2158static struct page *special_mapping_nopage(struct vm_area_struct *vma, 2159 unsigned long address, int *type) 2160{ 2161 struct page **pages; 2162 2163 BUG_ON(address < vma->vm_start || address >= vma->vm_end); 2164 2165 address -= vma->vm_start; 2166 for (pages = vma->vm_private_data; address > 0 && *pages; ++pages) 2167 address -= PAGE_SIZE; 2168 2169 if (*pages) { 2170 struct page *page = *pages; 2171 get_page(page); 2172 return page; 2173 } 2174 2175 return NOPAGE_SIGBUS; 2176} 2177 2178/* 2179 * Having a close hook prevents vma merging regardless of flags. 2180 */ 2181static void special_mapping_close(struct vm_area_struct *vma) 2182{ 2183} 2184 2185static struct vm_operations_struct special_mapping_vmops = { 2186 .close = special_mapping_close, 2187 .nopage = special_mapping_nopage, 2188}; 2189 2190/* 2191 * Called with mm->mmap_sem held for writing. 2192 * Insert a new vma covering the given region, with the given flags. 2193 * Its pages are supplied by the given array of struct page *. 2194 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2195 * The region past the last page supplied will always produce SIGBUS. 2196 * The array pointer and the pages it points to are assumed to stay alive 2197 * for as long as this mapping might exist. 2198 */ 2199int install_special_mapping(struct mm_struct *mm, 2200 unsigned long addr, unsigned long len, 2201 unsigned long vm_flags, struct page **pages) 2202{ 2203 struct vm_area_struct *vma; 2204 2205 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2206 if (unlikely(vma == NULL)) 2207 return -ENOMEM; 2208 2209 vma->vm_mm = mm; 2210 vma->vm_start = addr; 2211 vma->vm_end = addr + len; 2212 2213 vma->vm_flags = vm_flags | mm->def_flags; 2214 vma->vm_page_prot = protection_map[vma->vm_flags & 7]; 2215 2216 vma->vm_ops = &special_mapping_vmops; 2217 vma->vm_private_data = pages; 2218 2219 if (unlikely(insert_vm_struct(mm, vma))) { 2220 kmem_cache_free(vm_area_cachep, vma); 2221 return -ENOMEM; 2222 } 2223 2224 mm->total_vm += len >> PAGE_SHIFT; 2225 2226 return 0; 2227} 2228