mmap.c revision 659ace584e7a9fdda872eab4d6d7be1e0afb6cae
1/* 2 * mm/mmap.c 3 * 4 * Written by obz. 5 * 6 * Address space accounting code <alan@lxorguk.ukuu.org.uk> 7 */ 8 9#include <linux/slab.h> 10#include <linux/backing-dev.h> 11#include <linux/mm.h> 12#include <linux/shm.h> 13#include <linux/mman.h> 14#include <linux/pagemap.h> 15#include <linux/swap.h> 16#include <linux/syscalls.h> 17#include <linux/capability.h> 18#include <linux/init.h> 19#include <linux/file.h> 20#include <linux/fs.h> 21#include <linux/personality.h> 22#include <linux/security.h> 23#include <linux/hugetlb.h> 24#include <linux/profile.h> 25#include <linux/module.h> 26#include <linux/mount.h> 27#include <linux/mempolicy.h> 28#include <linux/rmap.h> 29#include <linux/mmu_notifier.h> 30#include <linux/perf_event.h> 31 32#include <asm/uaccess.h> 33#include <asm/cacheflush.h> 34#include <asm/tlb.h> 35#include <asm/mmu_context.h> 36 37#include "internal.h" 38 39#ifndef arch_mmap_check 40#define arch_mmap_check(addr, len, flags) (0) 41#endif 42 43#ifndef arch_rebalance_pgtables 44#define arch_rebalance_pgtables(addr, len) (addr) 45#endif 46 47static void unmap_region(struct mm_struct *mm, 48 struct vm_area_struct *vma, struct vm_area_struct *prev, 49 unsigned long start, unsigned long end); 50 51/* 52 * WARNING: the debugging will use recursive algorithms so never enable this 53 * unless you know what you are doing. 54 */ 55#undef DEBUG_MM_RB 56 57/* description of effects of mapping type and prot in current implementation. 58 * this is due to the limited x86 page protection hardware. The expected 59 * behavior is in parens: 60 * 61 * map_type prot 62 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 63 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 64 * w: (no) no w: (no) no w: (yes) yes w: (no) no 65 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 66 * 67 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 68 * w: (no) no w: (no) no w: (copy) copy w: (no) no 69 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 70 * 71 */ 72pgprot_t protection_map[16] = { 73 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 74 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 75}; 76 77pgprot_t vm_get_page_prot(unsigned long vm_flags) 78{ 79 return __pgprot(pgprot_val(protection_map[vm_flags & 80 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | 81 pgprot_val(arch_vm_get_page_prot(vm_flags))); 82} 83EXPORT_SYMBOL(vm_get_page_prot); 84 85int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 86int sysctl_overcommit_ratio = 50; /* default is 50% */ 87int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 88struct percpu_counter vm_committed_as; 89 90/* 91 * Check that a process has enough memory to allocate a new virtual 92 * mapping. 0 means there is enough memory for the allocation to 93 * succeed and -ENOMEM implies there is not. 94 * 95 * We currently support three overcommit policies, which are set via the 96 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 97 * 98 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 99 * Additional code 2002 Jul 20 by Robert Love. 100 * 101 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 102 * 103 * Note this is a helper function intended to be used by LSMs which 104 * wish to use this logic. 105 */ 106int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 107{ 108 unsigned long free, allowed; 109 110 vm_acct_memory(pages); 111 112 /* 113 * Sometimes we want to use more memory than we have 114 */ 115 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 116 return 0; 117 118 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 119 unsigned long n; 120 121 free = global_page_state(NR_FILE_PAGES); 122 free += nr_swap_pages; 123 124 /* 125 * Any slabs which are created with the 126 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 127 * which are reclaimable, under pressure. The dentry 128 * cache and most inode caches should fall into this 129 */ 130 free += global_page_state(NR_SLAB_RECLAIMABLE); 131 132 /* 133 * Leave the last 3% for root 134 */ 135 if (!cap_sys_admin) 136 free -= free / 32; 137 138 if (free > pages) 139 return 0; 140 141 /* 142 * nr_free_pages() is very expensive on large systems, 143 * only call if we're about to fail. 144 */ 145 n = nr_free_pages(); 146 147 /* 148 * Leave reserved pages. The pages are not for anonymous pages. 149 */ 150 if (n <= totalreserve_pages) 151 goto error; 152 else 153 n -= totalreserve_pages; 154 155 /* 156 * Leave the last 3% for root 157 */ 158 if (!cap_sys_admin) 159 n -= n / 32; 160 free += n; 161 162 if (free > pages) 163 return 0; 164 165 goto error; 166 } 167 168 allowed = (totalram_pages - hugetlb_total_pages()) 169 * sysctl_overcommit_ratio / 100; 170 /* 171 * Leave the last 3% for root 172 */ 173 if (!cap_sys_admin) 174 allowed -= allowed / 32; 175 allowed += total_swap_pages; 176 177 /* Don't let a single process grow too big: 178 leave 3% of the size of this process for other processes */ 179 if (mm) 180 allowed -= mm->total_vm / 32; 181 182 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 183 return 0; 184error: 185 vm_unacct_memory(pages); 186 187 return -ENOMEM; 188} 189 190/* 191 * Requires inode->i_mapping->i_mmap_lock 192 */ 193static void __remove_shared_vm_struct(struct vm_area_struct *vma, 194 struct file *file, struct address_space *mapping) 195{ 196 if (vma->vm_flags & VM_DENYWRITE) 197 atomic_inc(&file->f_path.dentry->d_inode->i_writecount); 198 if (vma->vm_flags & VM_SHARED) 199 mapping->i_mmap_writable--; 200 201 flush_dcache_mmap_lock(mapping); 202 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 203 list_del_init(&vma->shared.vm_set.list); 204 else 205 vma_prio_tree_remove(vma, &mapping->i_mmap); 206 flush_dcache_mmap_unlock(mapping); 207} 208 209/* 210 * Unlink a file-based vm structure from its prio_tree, to hide 211 * vma from rmap and vmtruncate before freeing its page tables. 212 */ 213void unlink_file_vma(struct vm_area_struct *vma) 214{ 215 struct file *file = vma->vm_file; 216 217 if (file) { 218 struct address_space *mapping = file->f_mapping; 219 spin_lock(&mapping->i_mmap_lock); 220 __remove_shared_vm_struct(vma, file, mapping); 221 spin_unlock(&mapping->i_mmap_lock); 222 } 223} 224 225/* 226 * Close a vm structure and free it, returning the next. 227 */ 228static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 229{ 230 struct vm_area_struct *next = vma->vm_next; 231 232 might_sleep(); 233 if (vma->vm_ops && vma->vm_ops->close) 234 vma->vm_ops->close(vma); 235 if (vma->vm_file) { 236 fput(vma->vm_file); 237 if (vma->vm_flags & VM_EXECUTABLE) 238 removed_exe_file_vma(vma->vm_mm); 239 } 240 mpol_put(vma_policy(vma)); 241 kmem_cache_free(vm_area_cachep, vma); 242 return next; 243} 244 245SYSCALL_DEFINE1(brk, unsigned long, brk) 246{ 247 unsigned long rlim, retval; 248 unsigned long newbrk, oldbrk; 249 struct mm_struct *mm = current->mm; 250 unsigned long min_brk; 251 252 down_write(&mm->mmap_sem); 253 254#ifdef CONFIG_COMPAT_BRK 255 min_brk = mm->end_code; 256#else 257 min_brk = mm->start_brk; 258#endif 259 if (brk < min_brk) 260 goto out; 261 262 /* 263 * Check against rlimit here. If this check is done later after the test 264 * of oldbrk with newbrk then it can escape the test and let the data 265 * segment grow beyond its set limit the in case where the limit is 266 * not page aligned -Ram Gupta 267 */ 268 rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; 269 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + 270 (mm->end_data - mm->start_data) > rlim) 271 goto out; 272 273 newbrk = PAGE_ALIGN(brk); 274 oldbrk = PAGE_ALIGN(mm->brk); 275 if (oldbrk == newbrk) 276 goto set_brk; 277 278 /* Always allow shrinking brk. */ 279 if (brk <= mm->brk) { 280 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 281 goto set_brk; 282 goto out; 283 } 284 285 /* Check against existing mmap mappings. */ 286 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 287 goto out; 288 289 /* Ok, looks good - let it rip. */ 290 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 291 goto out; 292set_brk: 293 mm->brk = brk; 294out: 295 retval = mm->brk; 296 up_write(&mm->mmap_sem); 297 return retval; 298} 299 300#ifdef DEBUG_MM_RB 301static int browse_rb(struct rb_root *root) 302{ 303 int i = 0, j; 304 struct rb_node *nd, *pn = NULL; 305 unsigned long prev = 0, pend = 0; 306 307 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 308 struct vm_area_struct *vma; 309 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 310 if (vma->vm_start < prev) 311 printk("vm_start %lx prev %lx\n", vma->vm_start, prev), i = -1; 312 if (vma->vm_start < pend) 313 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 314 if (vma->vm_start > vma->vm_end) 315 printk("vm_end %lx < vm_start %lx\n", vma->vm_end, vma->vm_start); 316 i++; 317 pn = nd; 318 prev = vma->vm_start; 319 pend = vma->vm_end; 320 } 321 j = 0; 322 for (nd = pn; nd; nd = rb_prev(nd)) { 323 j++; 324 } 325 if (i != j) 326 printk("backwards %d, forwards %d\n", j, i), i = 0; 327 return i; 328} 329 330void validate_mm(struct mm_struct *mm) 331{ 332 int bug = 0; 333 int i = 0; 334 struct vm_area_struct *tmp = mm->mmap; 335 while (tmp) { 336 tmp = tmp->vm_next; 337 i++; 338 } 339 if (i != mm->map_count) 340 printk("map_count %d vm_next %d\n", mm->map_count, i), bug = 1; 341 i = browse_rb(&mm->mm_rb); 342 if (i != mm->map_count) 343 printk("map_count %d rb %d\n", mm->map_count, i), bug = 1; 344 BUG_ON(bug); 345} 346#else 347#define validate_mm(mm) do { } while (0) 348#endif 349 350static struct vm_area_struct * 351find_vma_prepare(struct mm_struct *mm, unsigned long addr, 352 struct vm_area_struct **pprev, struct rb_node ***rb_link, 353 struct rb_node ** rb_parent) 354{ 355 struct vm_area_struct * vma; 356 struct rb_node ** __rb_link, * __rb_parent, * rb_prev; 357 358 __rb_link = &mm->mm_rb.rb_node; 359 rb_prev = __rb_parent = NULL; 360 vma = NULL; 361 362 while (*__rb_link) { 363 struct vm_area_struct *vma_tmp; 364 365 __rb_parent = *__rb_link; 366 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 367 368 if (vma_tmp->vm_end > addr) { 369 vma = vma_tmp; 370 if (vma_tmp->vm_start <= addr) 371 break; 372 __rb_link = &__rb_parent->rb_left; 373 } else { 374 rb_prev = __rb_parent; 375 __rb_link = &__rb_parent->rb_right; 376 } 377 } 378 379 *pprev = NULL; 380 if (rb_prev) 381 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 382 *rb_link = __rb_link; 383 *rb_parent = __rb_parent; 384 return vma; 385} 386 387static inline void 388__vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, 389 struct vm_area_struct *prev, struct rb_node *rb_parent) 390{ 391 if (prev) { 392 vma->vm_next = prev->vm_next; 393 prev->vm_next = vma; 394 } else { 395 mm->mmap = vma; 396 if (rb_parent) 397 vma->vm_next = rb_entry(rb_parent, 398 struct vm_area_struct, vm_rb); 399 else 400 vma->vm_next = NULL; 401 } 402} 403 404void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 405 struct rb_node **rb_link, struct rb_node *rb_parent) 406{ 407 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 408 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 409} 410 411static void __vma_link_file(struct vm_area_struct *vma) 412{ 413 struct file *file; 414 415 file = vma->vm_file; 416 if (file) { 417 struct address_space *mapping = file->f_mapping; 418 419 if (vma->vm_flags & VM_DENYWRITE) 420 atomic_dec(&file->f_path.dentry->d_inode->i_writecount); 421 if (vma->vm_flags & VM_SHARED) 422 mapping->i_mmap_writable++; 423 424 flush_dcache_mmap_lock(mapping); 425 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 426 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 427 else 428 vma_prio_tree_insert(vma, &mapping->i_mmap); 429 flush_dcache_mmap_unlock(mapping); 430 } 431} 432 433static void 434__vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 435 struct vm_area_struct *prev, struct rb_node **rb_link, 436 struct rb_node *rb_parent) 437{ 438 __vma_link_list(mm, vma, prev, rb_parent); 439 __vma_link_rb(mm, vma, rb_link, rb_parent); 440 __anon_vma_link(vma); 441} 442 443static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 444 struct vm_area_struct *prev, struct rb_node **rb_link, 445 struct rb_node *rb_parent) 446{ 447 struct address_space *mapping = NULL; 448 449 if (vma->vm_file) 450 mapping = vma->vm_file->f_mapping; 451 452 if (mapping) { 453 spin_lock(&mapping->i_mmap_lock); 454 vma->vm_truncate_count = mapping->truncate_count; 455 } 456 anon_vma_lock(vma); 457 458 __vma_link(mm, vma, prev, rb_link, rb_parent); 459 __vma_link_file(vma); 460 461 anon_vma_unlock(vma); 462 if (mapping) 463 spin_unlock(&mapping->i_mmap_lock); 464 465 mm->map_count++; 466 validate_mm(mm); 467} 468 469/* 470 * Helper for vma_adjust in the split_vma insert case: 471 * insert vm structure into list and rbtree and anon_vma, 472 * but it has already been inserted into prio_tree earlier. 473 */ 474static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 475{ 476 struct vm_area_struct *__vma, *prev; 477 struct rb_node **rb_link, *rb_parent; 478 479 __vma = find_vma_prepare(mm, vma->vm_start,&prev, &rb_link, &rb_parent); 480 BUG_ON(__vma && __vma->vm_start < vma->vm_end); 481 __vma_link(mm, vma, prev, rb_link, rb_parent); 482 mm->map_count++; 483} 484 485static inline void 486__vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 487 struct vm_area_struct *prev) 488{ 489 prev->vm_next = vma->vm_next; 490 rb_erase(&vma->vm_rb, &mm->mm_rb); 491 if (mm->mmap_cache == vma) 492 mm->mmap_cache = prev; 493} 494 495/* 496 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 497 * is already present in an i_mmap tree without adjusting the tree. 498 * The following helper function should be used when such adjustments 499 * are necessary. The "insert" vma (if any) is to be inserted 500 * before we drop the necessary locks. 501 */ 502void vma_adjust(struct vm_area_struct *vma, unsigned long start, 503 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 504{ 505 struct mm_struct *mm = vma->vm_mm; 506 struct vm_area_struct *next = vma->vm_next; 507 struct vm_area_struct *importer = NULL; 508 struct address_space *mapping = NULL; 509 struct prio_tree_root *root = NULL; 510 struct file *file = vma->vm_file; 511 struct anon_vma *anon_vma = NULL; 512 long adjust_next = 0; 513 int remove_next = 0; 514 515 if (next && !insert) { 516 if (end >= next->vm_end) { 517 /* 518 * vma expands, overlapping all the next, and 519 * perhaps the one after too (mprotect case 6). 520 */ 521again: remove_next = 1 + (end > next->vm_end); 522 end = next->vm_end; 523 anon_vma = next->anon_vma; 524 importer = vma; 525 } else if (end > next->vm_start) { 526 /* 527 * vma expands, overlapping part of the next: 528 * mprotect case 5 shifting the boundary up. 529 */ 530 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 531 anon_vma = next->anon_vma; 532 importer = vma; 533 } else if (end < vma->vm_end) { 534 /* 535 * vma shrinks, and !insert tells it's not 536 * split_vma inserting another: so it must be 537 * mprotect case 4 shifting the boundary down. 538 */ 539 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 540 anon_vma = next->anon_vma; 541 importer = next; 542 } 543 } 544 545 if (file) { 546 mapping = file->f_mapping; 547 if (!(vma->vm_flags & VM_NONLINEAR)) 548 root = &mapping->i_mmap; 549 spin_lock(&mapping->i_mmap_lock); 550 if (importer && 551 vma->vm_truncate_count != next->vm_truncate_count) { 552 /* 553 * unmap_mapping_range might be in progress: 554 * ensure that the expanding vma is rescanned. 555 */ 556 importer->vm_truncate_count = 0; 557 } 558 if (insert) { 559 insert->vm_truncate_count = vma->vm_truncate_count; 560 /* 561 * Put into prio_tree now, so instantiated pages 562 * are visible to arm/parisc __flush_dcache_page 563 * throughout; but we cannot insert into address 564 * space until vma start or end is updated. 565 */ 566 __vma_link_file(insert); 567 } 568 } 569 570 /* 571 * When changing only vma->vm_end, we don't really need 572 * anon_vma lock. 573 */ 574 if (vma->anon_vma && (insert || importer || start != vma->vm_start)) 575 anon_vma = vma->anon_vma; 576 if (anon_vma) { 577 spin_lock(&anon_vma->lock); 578 /* 579 * Easily overlooked: when mprotect shifts the boundary, 580 * make sure the expanding vma has anon_vma set if the 581 * shrinking vma had, to cover any anon pages imported. 582 */ 583 if (importer && !importer->anon_vma) { 584 importer->anon_vma = anon_vma; 585 __anon_vma_link(importer); 586 } 587 } 588 589 if (root) { 590 flush_dcache_mmap_lock(mapping); 591 vma_prio_tree_remove(vma, root); 592 if (adjust_next) 593 vma_prio_tree_remove(next, root); 594 } 595 596 vma->vm_start = start; 597 vma->vm_end = end; 598 vma->vm_pgoff = pgoff; 599 if (adjust_next) { 600 next->vm_start += adjust_next << PAGE_SHIFT; 601 next->vm_pgoff += adjust_next; 602 } 603 604 if (root) { 605 if (adjust_next) 606 vma_prio_tree_insert(next, root); 607 vma_prio_tree_insert(vma, root); 608 flush_dcache_mmap_unlock(mapping); 609 } 610 611 if (remove_next) { 612 /* 613 * vma_merge has merged next into vma, and needs 614 * us to remove next before dropping the locks. 615 */ 616 __vma_unlink(mm, next, vma); 617 if (file) 618 __remove_shared_vm_struct(next, file, mapping); 619 if (next->anon_vma) 620 __anon_vma_merge(vma, next); 621 } else if (insert) { 622 /* 623 * split_vma has split insert from vma, and needs 624 * us to insert it before dropping the locks 625 * (it may either follow vma or precede it). 626 */ 627 __insert_vm_struct(mm, insert); 628 } 629 630 if (anon_vma) 631 spin_unlock(&anon_vma->lock); 632 if (mapping) 633 spin_unlock(&mapping->i_mmap_lock); 634 635 if (remove_next) { 636 if (file) { 637 fput(file); 638 if (next->vm_flags & VM_EXECUTABLE) 639 removed_exe_file_vma(mm); 640 } 641 mm->map_count--; 642 mpol_put(vma_policy(next)); 643 kmem_cache_free(vm_area_cachep, next); 644 /* 645 * In mprotect's case 6 (see comments on vma_merge), 646 * we must remove another next too. It would clutter 647 * up the code too much to do both in one go. 648 */ 649 if (remove_next == 2) { 650 next = vma->vm_next; 651 goto again; 652 } 653 } 654 655 validate_mm(mm); 656} 657 658/* 659 * If the vma has a ->close operation then the driver probably needs to release 660 * per-vma resources, so we don't attempt to merge those. 661 */ 662static inline int is_mergeable_vma(struct vm_area_struct *vma, 663 struct file *file, unsigned long vm_flags) 664{ 665 /* VM_CAN_NONLINEAR may get set later by f_op->mmap() */ 666 if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR) 667 return 0; 668 if (vma->vm_file != file) 669 return 0; 670 if (vma->vm_ops && vma->vm_ops->close) 671 return 0; 672 return 1; 673} 674 675static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 676 struct anon_vma *anon_vma2) 677{ 678 return !anon_vma1 || !anon_vma2 || (anon_vma1 == anon_vma2); 679} 680 681/* 682 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 683 * in front of (at a lower virtual address and file offset than) the vma. 684 * 685 * We cannot merge two vmas if they have differently assigned (non-NULL) 686 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 687 * 688 * We don't check here for the merged mmap wrapping around the end of pagecache 689 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 690 * wrap, nor mmaps which cover the final page at index -1UL. 691 */ 692static int 693can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 694 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 695{ 696 if (is_mergeable_vma(vma, file, vm_flags) && 697 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 698 if (vma->vm_pgoff == vm_pgoff) 699 return 1; 700 } 701 return 0; 702} 703 704/* 705 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 706 * beyond (at a higher virtual address and file offset than) the vma. 707 * 708 * We cannot merge two vmas if they have differently assigned (non-NULL) 709 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 710 */ 711static int 712can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 713 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 714{ 715 if (is_mergeable_vma(vma, file, vm_flags) && 716 is_mergeable_anon_vma(anon_vma, vma->anon_vma)) { 717 pgoff_t vm_pglen; 718 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 719 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 720 return 1; 721 } 722 return 0; 723} 724 725/* 726 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 727 * whether that can be merged with its predecessor or its successor. 728 * Or both (it neatly fills a hole). 729 * 730 * In most cases - when called for mmap, brk or mremap - [addr,end) is 731 * certain not to be mapped by the time vma_merge is called; but when 732 * called for mprotect, it is certain to be already mapped (either at 733 * an offset within prev, or at the start of next), and the flags of 734 * this area are about to be changed to vm_flags - and the no-change 735 * case has already been eliminated. 736 * 737 * The following mprotect cases have to be considered, where AAAA is 738 * the area passed down from mprotect_fixup, never extending beyond one 739 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 740 * 741 * AAAA AAAA AAAA AAAA 742 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 743 * cannot merge might become might become might become 744 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 745 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 746 * mremap move: PPPPNNNNNNNN 8 747 * AAAA 748 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 749 * might become case 1 below case 2 below case 3 below 750 * 751 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 752 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 753 */ 754struct vm_area_struct *vma_merge(struct mm_struct *mm, 755 struct vm_area_struct *prev, unsigned long addr, 756 unsigned long end, unsigned long vm_flags, 757 struct anon_vma *anon_vma, struct file *file, 758 pgoff_t pgoff, struct mempolicy *policy) 759{ 760 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 761 struct vm_area_struct *area, *next; 762 763 /* 764 * We later require that vma->vm_flags == vm_flags, 765 * so this tests vma->vm_flags & VM_SPECIAL, too. 766 */ 767 if (vm_flags & VM_SPECIAL) 768 return NULL; 769 770 if (prev) 771 next = prev->vm_next; 772 else 773 next = mm->mmap; 774 area = next; 775 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 776 next = next->vm_next; 777 778 /* 779 * Can it merge with the predecessor? 780 */ 781 if (prev && prev->vm_end == addr && 782 mpol_equal(vma_policy(prev), policy) && 783 can_vma_merge_after(prev, vm_flags, 784 anon_vma, file, pgoff)) { 785 /* 786 * OK, it can. Can we now merge in the successor as well? 787 */ 788 if (next && end == next->vm_start && 789 mpol_equal(policy, vma_policy(next)) && 790 can_vma_merge_before(next, vm_flags, 791 anon_vma, file, pgoff+pglen) && 792 is_mergeable_anon_vma(prev->anon_vma, 793 next->anon_vma)) { 794 /* cases 1, 6 */ 795 vma_adjust(prev, prev->vm_start, 796 next->vm_end, prev->vm_pgoff, NULL); 797 } else /* cases 2, 5, 7 */ 798 vma_adjust(prev, prev->vm_start, 799 end, prev->vm_pgoff, NULL); 800 return prev; 801 } 802 803 /* 804 * Can this new request be merged in front of next? 805 */ 806 if (next && end == next->vm_start && 807 mpol_equal(policy, vma_policy(next)) && 808 can_vma_merge_before(next, vm_flags, 809 anon_vma, file, pgoff+pglen)) { 810 if (prev && addr < prev->vm_end) /* case 4 */ 811 vma_adjust(prev, prev->vm_start, 812 addr, prev->vm_pgoff, NULL); 813 else /* cases 3, 8 */ 814 vma_adjust(area, addr, next->vm_end, 815 next->vm_pgoff - pglen, NULL); 816 return area; 817 } 818 819 return NULL; 820} 821 822/* 823 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 824 * neighbouring vmas for a suitable anon_vma, before it goes off 825 * to allocate a new anon_vma. It checks because a repetitive 826 * sequence of mprotects and faults may otherwise lead to distinct 827 * anon_vmas being allocated, preventing vma merge in subsequent 828 * mprotect. 829 */ 830struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 831{ 832 struct vm_area_struct *near; 833 unsigned long vm_flags; 834 835 near = vma->vm_next; 836 if (!near) 837 goto try_prev; 838 839 /* 840 * Since only mprotect tries to remerge vmas, match flags 841 * which might be mprotected into each other later on. 842 * Neither mlock nor madvise tries to remerge at present, 843 * so leave their flags as obstructing a merge. 844 */ 845 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 846 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 847 848 if (near->anon_vma && vma->vm_end == near->vm_start && 849 mpol_equal(vma_policy(vma), vma_policy(near)) && 850 can_vma_merge_before(near, vm_flags, 851 NULL, vma->vm_file, vma->vm_pgoff + 852 ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT))) 853 return near->anon_vma; 854try_prev: 855 /* 856 * It is potentially slow to have to call find_vma_prev here. 857 * But it's only on the first write fault on the vma, not 858 * every time, and we could devise a way to avoid it later 859 * (e.g. stash info in next's anon_vma_node when assigning 860 * an anon_vma, or when trying vma_merge). Another time. 861 */ 862 BUG_ON(find_vma_prev(vma->vm_mm, vma->vm_start, &near) != vma); 863 if (!near) 864 goto none; 865 866 vm_flags = vma->vm_flags & ~(VM_READ|VM_WRITE|VM_EXEC); 867 vm_flags |= near->vm_flags & (VM_READ|VM_WRITE|VM_EXEC); 868 869 if (near->anon_vma && near->vm_end == vma->vm_start && 870 mpol_equal(vma_policy(near), vma_policy(vma)) && 871 can_vma_merge_after(near, vm_flags, 872 NULL, vma->vm_file, vma->vm_pgoff)) 873 return near->anon_vma; 874none: 875 /* 876 * There's no absolute need to look only at touching neighbours: 877 * we could search further afield for "compatible" anon_vmas. 878 * But it would probably just be a waste of time searching, 879 * or lead to too many vmas hanging off the same anon_vma. 880 * We're trying to allow mprotect remerging later on, 881 * not trying to minimize memory used for anon_vmas. 882 */ 883 return NULL; 884} 885 886#ifdef CONFIG_PROC_FS 887void vm_stat_account(struct mm_struct *mm, unsigned long flags, 888 struct file *file, long pages) 889{ 890 const unsigned long stack_flags 891 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 892 893 if (file) { 894 mm->shared_vm += pages; 895 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 896 mm->exec_vm += pages; 897 } else if (flags & stack_flags) 898 mm->stack_vm += pages; 899 if (flags & (VM_RESERVED|VM_IO)) 900 mm->reserved_vm += pages; 901} 902#endif /* CONFIG_PROC_FS */ 903 904/* 905 * The caller must hold down_write(¤t->mm->mmap_sem). 906 */ 907 908unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, 909 unsigned long len, unsigned long prot, 910 unsigned long flags, unsigned long pgoff) 911{ 912 struct mm_struct * mm = current->mm; 913 struct inode *inode; 914 unsigned int vm_flags; 915 int error; 916 unsigned long reqprot = prot; 917 918 /* 919 * Does the application expect PROT_READ to imply PROT_EXEC? 920 * 921 * (the exception is when the underlying filesystem is noexec 922 * mounted, in which case we dont add PROT_EXEC.) 923 */ 924 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 925 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 926 prot |= PROT_EXEC; 927 928 if (!len) 929 return -EINVAL; 930 931 if (!(flags & MAP_FIXED)) 932 addr = round_hint_to_min(addr); 933 934 /* Careful about overflows.. */ 935 len = PAGE_ALIGN(len); 936 if (!len) 937 return -ENOMEM; 938 939 /* offset overflow? */ 940 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 941 return -EOVERFLOW; 942 943 /* Too many mappings? */ 944 if (mm->map_count > sysctl_max_map_count) 945 return -ENOMEM; 946 947 /* Obtain the address to map to. we verify (or select) it and ensure 948 * that it represents a valid section of the address space. 949 */ 950 addr = get_unmapped_area(file, addr, len, pgoff, flags); 951 if (addr & ~PAGE_MASK) 952 return addr; 953 954 /* Do simple checking here so the lower-level routines won't have 955 * to. we assume access permissions have been handled by the open 956 * of the memory object, so we don't do any here. 957 */ 958 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 959 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 960 961 if (flags & MAP_LOCKED) 962 if (!can_do_mlock()) 963 return -EPERM; 964 965 /* mlock MCL_FUTURE? */ 966 if (vm_flags & VM_LOCKED) { 967 unsigned long locked, lock_limit; 968 locked = len >> PAGE_SHIFT; 969 locked += mm->locked_vm; 970 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 971 lock_limit >>= PAGE_SHIFT; 972 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 973 return -EAGAIN; 974 } 975 976 inode = file ? file->f_path.dentry->d_inode : NULL; 977 978 if (file) { 979 switch (flags & MAP_TYPE) { 980 case MAP_SHARED: 981 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 982 return -EACCES; 983 984 /* 985 * Make sure we don't allow writing to an append-only 986 * file.. 987 */ 988 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 989 return -EACCES; 990 991 /* 992 * Make sure there are no mandatory locks on the file. 993 */ 994 if (locks_verify_locked(inode)) 995 return -EAGAIN; 996 997 vm_flags |= VM_SHARED | VM_MAYSHARE; 998 if (!(file->f_mode & FMODE_WRITE)) 999 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1000 1001 /* fall through */ 1002 case MAP_PRIVATE: 1003 if (!(file->f_mode & FMODE_READ)) 1004 return -EACCES; 1005 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1006 if (vm_flags & VM_EXEC) 1007 return -EPERM; 1008 vm_flags &= ~VM_MAYEXEC; 1009 } 1010 1011 if (!file->f_op || !file->f_op->mmap) 1012 return -ENODEV; 1013 break; 1014 1015 default: 1016 return -EINVAL; 1017 } 1018 } else { 1019 switch (flags & MAP_TYPE) { 1020 case MAP_SHARED: 1021 /* 1022 * Ignore pgoff. 1023 */ 1024 pgoff = 0; 1025 vm_flags |= VM_SHARED | VM_MAYSHARE; 1026 break; 1027 case MAP_PRIVATE: 1028 /* 1029 * Set pgoff according to addr for anon_vma. 1030 */ 1031 pgoff = addr >> PAGE_SHIFT; 1032 break; 1033 default: 1034 return -EINVAL; 1035 } 1036 } 1037 1038 error = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1039 if (error) 1040 return error; 1041 1042 return mmap_region(file, addr, len, flags, vm_flags, pgoff); 1043} 1044EXPORT_SYMBOL(do_mmap_pgoff); 1045 1046/* 1047 * Some shared mappigns will want the pages marked read-only 1048 * to track write events. If so, we'll downgrade vm_page_prot 1049 * to the private version (using protection_map[] without the 1050 * VM_SHARED bit). 1051 */ 1052int vma_wants_writenotify(struct vm_area_struct *vma) 1053{ 1054 unsigned int vm_flags = vma->vm_flags; 1055 1056 /* If it was private or non-writable, the write bit is already clear */ 1057 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1058 return 0; 1059 1060 /* The backer wishes to know when pages are first written to? */ 1061 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1062 return 1; 1063 1064 /* The open routine did something to the protections already? */ 1065 if (pgprot_val(vma->vm_page_prot) != 1066 pgprot_val(vm_get_page_prot(vm_flags))) 1067 return 0; 1068 1069 /* Specialty mapping? */ 1070 if (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) 1071 return 0; 1072 1073 /* Can the mapping track the dirty pages? */ 1074 return vma->vm_file && vma->vm_file->f_mapping && 1075 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1076} 1077 1078/* 1079 * We account for memory if it's a private writeable mapping, 1080 * not hugepages and VM_NORESERVE wasn't set. 1081 */ 1082static inline int accountable_mapping(struct file *file, unsigned int vm_flags) 1083{ 1084 /* 1085 * hugetlb has its own accounting separate from the core VM 1086 * VM_HUGETLB may not be set yet so we cannot check for that flag. 1087 */ 1088 if (file && is_file_hugepages(file)) 1089 return 0; 1090 1091 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; 1092} 1093 1094unsigned long mmap_region(struct file *file, unsigned long addr, 1095 unsigned long len, unsigned long flags, 1096 unsigned int vm_flags, unsigned long pgoff) 1097{ 1098 struct mm_struct *mm = current->mm; 1099 struct vm_area_struct *vma, *prev; 1100 int correct_wcount = 0; 1101 int error; 1102 struct rb_node **rb_link, *rb_parent; 1103 unsigned long charged = 0; 1104 struct inode *inode = file ? file->f_path.dentry->d_inode : NULL; 1105 1106 /* Clear old maps */ 1107 error = -ENOMEM; 1108munmap_back: 1109 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 1110 if (vma && vma->vm_start < addr + len) { 1111 if (do_munmap(mm, addr, len)) 1112 return -ENOMEM; 1113 goto munmap_back; 1114 } 1115 1116 /* Check against address space limit. */ 1117 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1118 return -ENOMEM; 1119 1120 /* 1121 * Set 'VM_NORESERVE' if we should not account for the 1122 * memory use of this mapping. 1123 */ 1124 if ((flags & MAP_NORESERVE)) { 1125 /* We honor MAP_NORESERVE if allowed to overcommit */ 1126 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) 1127 vm_flags |= VM_NORESERVE; 1128 1129 /* hugetlb applies strict overcommit unless MAP_NORESERVE */ 1130 if (file && is_file_hugepages(file)) 1131 vm_flags |= VM_NORESERVE; 1132 } 1133 1134 /* 1135 * Private writable mapping: check memory availability 1136 */ 1137 if (accountable_mapping(file, vm_flags)) { 1138 charged = len >> PAGE_SHIFT; 1139 if (security_vm_enough_memory(charged)) 1140 return -ENOMEM; 1141 vm_flags |= VM_ACCOUNT; 1142 } 1143 1144 /* 1145 * Can we just expand an old mapping? 1146 */ 1147 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL); 1148 if (vma) 1149 goto out; 1150 1151 /* 1152 * Determine the object being mapped and call the appropriate 1153 * specific mapper. the address has already been validated, but 1154 * not unmapped, but the maps are removed from the list. 1155 */ 1156 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1157 if (!vma) { 1158 error = -ENOMEM; 1159 goto unacct_error; 1160 } 1161 1162 vma->vm_mm = mm; 1163 vma->vm_start = addr; 1164 vma->vm_end = addr + len; 1165 vma->vm_flags = vm_flags; 1166 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1167 vma->vm_pgoff = pgoff; 1168 1169 if (file) { 1170 error = -EINVAL; 1171 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1172 goto free_vma; 1173 if (vm_flags & VM_DENYWRITE) { 1174 error = deny_write_access(file); 1175 if (error) 1176 goto free_vma; 1177 correct_wcount = 1; 1178 } 1179 vma->vm_file = file; 1180 get_file(file); 1181 error = file->f_op->mmap(file, vma); 1182 if (error) 1183 goto unmap_and_free_vma; 1184 if (vm_flags & VM_EXECUTABLE) 1185 added_exe_file_vma(mm); 1186 1187 /* Can addr have changed?? 1188 * 1189 * Answer: Yes, several device drivers can do it in their 1190 * f_op->mmap method. -DaveM 1191 */ 1192 addr = vma->vm_start; 1193 pgoff = vma->vm_pgoff; 1194 vm_flags = vma->vm_flags; 1195 } else if (vm_flags & VM_SHARED) { 1196 error = shmem_zero_setup(vma); 1197 if (error) 1198 goto free_vma; 1199 } 1200 1201 if (vma_wants_writenotify(vma)) 1202 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); 1203 1204 vma_link(mm, vma, prev, rb_link, rb_parent); 1205 file = vma->vm_file; 1206 1207 /* Once vma denies write, undo our temporary denial count */ 1208 if (correct_wcount) 1209 atomic_inc(&inode->i_writecount); 1210out: 1211 perf_event_mmap(vma); 1212 1213 mm->total_vm += len >> PAGE_SHIFT; 1214 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1215 if (vm_flags & VM_LOCKED) { 1216 /* 1217 * makes pages present; downgrades, drops, reacquires mmap_sem 1218 */ 1219 long nr_pages = mlock_vma_pages_range(vma, addr, addr + len); 1220 if (nr_pages < 0) 1221 return nr_pages; /* vma gone! */ 1222 mm->locked_vm += (len >> PAGE_SHIFT) - nr_pages; 1223 } else if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK)) 1224 make_pages_present(addr, addr + len); 1225 return addr; 1226 1227unmap_and_free_vma: 1228 if (correct_wcount) 1229 atomic_inc(&inode->i_writecount); 1230 vma->vm_file = NULL; 1231 fput(file); 1232 1233 /* Undo any partial mapping done by a device driver. */ 1234 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1235 charged = 0; 1236free_vma: 1237 kmem_cache_free(vm_area_cachep, vma); 1238unacct_error: 1239 if (charged) 1240 vm_unacct_memory(charged); 1241 return error; 1242} 1243 1244/* Get an address range which is currently unmapped. 1245 * For shmat() with addr=0. 1246 * 1247 * Ugly calling convention alert: 1248 * Return value with the low bits set means error value, 1249 * ie 1250 * if (ret & ~PAGE_MASK) 1251 * error = ret; 1252 * 1253 * This function "knows" that -ENOMEM has the bits set. 1254 */ 1255#ifndef HAVE_ARCH_UNMAPPED_AREA 1256unsigned long 1257arch_get_unmapped_area(struct file *filp, unsigned long addr, 1258 unsigned long len, unsigned long pgoff, unsigned long flags) 1259{ 1260 struct mm_struct *mm = current->mm; 1261 struct vm_area_struct *vma; 1262 unsigned long start_addr; 1263 1264 if (len > TASK_SIZE) 1265 return -ENOMEM; 1266 1267 if (flags & MAP_FIXED) 1268 return addr; 1269 1270 if (addr) { 1271 addr = PAGE_ALIGN(addr); 1272 vma = find_vma(mm, addr); 1273 if (TASK_SIZE - len >= addr && 1274 (!vma || addr + len <= vma->vm_start)) 1275 return addr; 1276 } 1277 if (len > mm->cached_hole_size) { 1278 start_addr = addr = mm->free_area_cache; 1279 } else { 1280 start_addr = addr = TASK_UNMAPPED_BASE; 1281 mm->cached_hole_size = 0; 1282 } 1283 1284full_search: 1285 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 1286 /* At this point: (!vma || addr < vma->vm_end). */ 1287 if (TASK_SIZE - len < addr) { 1288 /* 1289 * Start a new search - just in case we missed 1290 * some holes. 1291 */ 1292 if (start_addr != TASK_UNMAPPED_BASE) { 1293 addr = TASK_UNMAPPED_BASE; 1294 start_addr = addr; 1295 mm->cached_hole_size = 0; 1296 goto full_search; 1297 } 1298 return -ENOMEM; 1299 } 1300 if (!vma || addr + len <= vma->vm_start) { 1301 /* 1302 * Remember the place where we stopped the search: 1303 */ 1304 mm->free_area_cache = addr + len; 1305 return addr; 1306 } 1307 if (addr + mm->cached_hole_size < vma->vm_start) 1308 mm->cached_hole_size = vma->vm_start - addr; 1309 addr = vma->vm_end; 1310 } 1311} 1312#endif 1313 1314void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1315{ 1316 /* 1317 * Is this a new hole at the lowest possible address? 1318 */ 1319 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) { 1320 mm->free_area_cache = addr; 1321 mm->cached_hole_size = ~0UL; 1322 } 1323} 1324 1325/* 1326 * This mmap-allocator allocates new areas top-down from below the 1327 * stack's low limit (the base): 1328 */ 1329#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1330unsigned long 1331arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1332 const unsigned long len, const unsigned long pgoff, 1333 const unsigned long flags) 1334{ 1335 struct vm_area_struct *vma; 1336 struct mm_struct *mm = current->mm; 1337 unsigned long addr = addr0; 1338 1339 /* requested length too big for entire address space */ 1340 if (len > TASK_SIZE) 1341 return -ENOMEM; 1342 1343 if (flags & MAP_FIXED) 1344 return addr; 1345 1346 /* requesting a specific address */ 1347 if (addr) { 1348 addr = PAGE_ALIGN(addr); 1349 vma = find_vma(mm, addr); 1350 if (TASK_SIZE - len >= addr && 1351 (!vma || addr + len <= vma->vm_start)) 1352 return addr; 1353 } 1354 1355 /* check if free_area_cache is useful for us */ 1356 if (len <= mm->cached_hole_size) { 1357 mm->cached_hole_size = 0; 1358 mm->free_area_cache = mm->mmap_base; 1359 } 1360 1361 /* either no address requested or can't fit in requested address hole */ 1362 addr = mm->free_area_cache; 1363 1364 /* make sure it can fit in the remaining address space */ 1365 if (addr > len) { 1366 vma = find_vma(mm, addr-len); 1367 if (!vma || addr <= vma->vm_start) 1368 /* remember the address as a hint for next time */ 1369 return (mm->free_area_cache = addr-len); 1370 } 1371 1372 if (mm->mmap_base < len) 1373 goto bottomup; 1374 1375 addr = mm->mmap_base-len; 1376 1377 do { 1378 /* 1379 * Lookup failure means no vma is above this address, 1380 * else if new region fits below vma->vm_start, 1381 * return with success: 1382 */ 1383 vma = find_vma(mm, addr); 1384 if (!vma || addr+len <= vma->vm_start) 1385 /* remember the address as a hint for next time */ 1386 return (mm->free_area_cache = addr); 1387 1388 /* remember the largest hole we saw so far */ 1389 if (addr + mm->cached_hole_size < vma->vm_start) 1390 mm->cached_hole_size = vma->vm_start - addr; 1391 1392 /* try just below the current vma->vm_start */ 1393 addr = vma->vm_start-len; 1394 } while (len < vma->vm_start); 1395 1396bottomup: 1397 /* 1398 * A failed mmap() very likely causes application failure, 1399 * so fall back to the bottom-up function here. This scenario 1400 * can happen with large stack limits and large mmap() 1401 * allocations. 1402 */ 1403 mm->cached_hole_size = ~0UL; 1404 mm->free_area_cache = TASK_UNMAPPED_BASE; 1405 addr = arch_get_unmapped_area(filp, addr0, len, pgoff, flags); 1406 /* 1407 * Restore the topdown base: 1408 */ 1409 mm->free_area_cache = mm->mmap_base; 1410 mm->cached_hole_size = ~0UL; 1411 1412 return addr; 1413} 1414#endif 1415 1416void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1417{ 1418 /* 1419 * Is this a new hole at the highest possible address? 1420 */ 1421 if (addr > mm->free_area_cache) 1422 mm->free_area_cache = addr; 1423 1424 /* dont allow allocations above current base */ 1425 if (mm->free_area_cache > mm->mmap_base) 1426 mm->free_area_cache = mm->mmap_base; 1427} 1428 1429unsigned long 1430get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1431 unsigned long pgoff, unsigned long flags) 1432{ 1433 unsigned long (*get_area)(struct file *, unsigned long, 1434 unsigned long, unsigned long, unsigned long); 1435 1436 unsigned long error = arch_mmap_check(addr, len, flags); 1437 if (error) 1438 return error; 1439 1440 /* Careful about overflows.. */ 1441 if (len > TASK_SIZE) 1442 return -ENOMEM; 1443 1444 get_area = current->mm->get_unmapped_area; 1445 if (file && file->f_op && file->f_op->get_unmapped_area) 1446 get_area = file->f_op->get_unmapped_area; 1447 addr = get_area(file, addr, len, pgoff, flags); 1448 if (IS_ERR_VALUE(addr)) 1449 return addr; 1450 1451 if (addr > TASK_SIZE - len) 1452 return -ENOMEM; 1453 if (addr & ~PAGE_MASK) 1454 return -EINVAL; 1455 1456 return arch_rebalance_pgtables(addr, len); 1457} 1458 1459EXPORT_SYMBOL(get_unmapped_area); 1460 1461/* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1462struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 1463{ 1464 struct vm_area_struct *vma = NULL; 1465 1466 if (mm) { 1467 /* Check the cache first. */ 1468 /* (Cache hit rate is typically around 35%.) */ 1469 vma = mm->mmap_cache; 1470 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1471 struct rb_node * rb_node; 1472 1473 rb_node = mm->mm_rb.rb_node; 1474 vma = NULL; 1475 1476 while (rb_node) { 1477 struct vm_area_struct * vma_tmp; 1478 1479 vma_tmp = rb_entry(rb_node, 1480 struct vm_area_struct, vm_rb); 1481 1482 if (vma_tmp->vm_end > addr) { 1483 vma = vma_tmp; 1484 if (vma_tmp->vm_start <= addr) 1485 break; 1486 rb_node = rb_node->rb_left; 1487 } else 1488 rb_node = rb_node->rb_right; 1489 } 1490 if (vma) 1491 mm->mmap_cache = vma; 1492 } 1493 } 1494 return vma; 1495} 1496 1497EXPORT_SYMBOL(find_vma); 1498 1499/* Same as find_vma, but also return a pointer to the previous VMA in *pprev. */ 1500struct vm_area_struct * 1501find_vma_prev(struct mm_struct *mm, unsigned long addr, 1502 struct vm_area_struct **pprev) 1503{ 1504 struct vm_area_struct *vma = NULL, *prev = NULL; 1505 struct rb_node *rb_node; 1506 if (!mm) 1507 goto out; 1508 1509 /* Guard against addr being lower than the first VMA */ 1510 vma = mm->mmap; 1511 1512 /* Go through the RB tree quickly. */ 1513 rb_node = mm->mm_rb.rb_node; 1514 1515 while (rb_node) { 1516 struct vm_area_struct *vma_tmp; 1517 vma_tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1518 1519 if (addr < vma_tmp->vm_end) { 1520 rb_node = rb_node->rb_left; 1521 } else { 1522 prev = vma_tmp; 1523 if (!prev->vm_next || (addr < prev->vm_next->vm_end)) 1524 break; 1525 rb_node = rb_node->rb_right; 1526 } 1527 } 1528 1529out: 1530 *pprev = prev; 1531 return prev ? prev->vm_next : vma; 1532} 1533 1534/* 1535 * Verify that the stack growth is acceptable and 1536 * update accounting. This is shared with both the 1537 * grow-up and grow-down cases. 1538 */ 1539static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) 1540{ 1541 struct mm_struct *mm = vma->vm_mm; 1542 struct rlimit *rlim = current->signal->rlim; 1543 unsigned long new_start; 1544 1545 /* address space limit tests */ 1546 if (!may_expand_vm(mm, grow)) 1547 return -ENOMEM; 1548 1549 /* Stack limit test */ 1550 if (size > rlim[RLIMIT_STACK].rlim_cur) 1551 return -ENOMEM; 1552 1553 /* mlock limit tests */ 1554 if (vma->vm_flags & VM_LOCKED) { 1555 unsigned long locked; 1556 unsigned long limit; 1557 locked = mm->locked_vm + grow; 1558 limit = rlim[RLIMIT_MEMLOCK].rlim_cur >> PAGE_SHIFT; 1559 if (locked > limit && !capable(CAP_IPC_LOCK)) 1560 return -ENOMEM; 1561 } 1562 1563 /* Check to ensure the stack will not grow into a hugetlb-only region */ 1564 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 1565 vma->vm_end - size; 1566 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 1567 return -EFAULT; 1568 1569 /* 1570 * Overcommit.. This must be the final test, as it will 1571 * update security statistics. 1572 */ 1573 if (security_vm_enough_memory_mm(mm, grow)) 1574 return -ENOMEM; 1575 1576 /* Ok, everything looks good - let it rip */ 1577 mm->total_vm += grow; 1578 if (vma->vm_flags & VM_LOCKED) 1579 mm->locked_vm += grow; 1580 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 1581 return 0; 1582} 1583 1584#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 1585/* 1586 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 1587 * vma is the last one with address > vma->vm_end. Have to extend vma. 1588 */ 1589#ifndef CONFIG_IA64 1590static 1591#endif 1592int expand_upwards(struct vm_area_struct *vma, unsigned long address) 1593{ 1594 int error; 1595 1596 if (!(vma->vm_flags & VM_GROWSUP)) 1597 return -EFAULT; 1598 1599 /* 1600 * We must make sure the anon_vma is allocated 1601 * so that the anon_vma locking is not a noop. 1602 */ 1603 if (unlikely(anon_vma_prepare(vma))) 1604 return -ENOMEM; 1605 anon_vma_lock(vma); 1606 1607 /* 1608 * vma->vm_start/vm_end cannot change under us because the caller 1609 * is required to hold the mmap_sem in read mode. We need the 1610 * anon_vma lock to serialize against concurrent expand_stacks. 1611 * Also guard against wrapping around to address 0. 1612 */ 1613 if (address < PAGE_ALIGN(address+4)) 1614 address = PAGE_ALIGN(address+4); 1615 else { 1616 anon_vma_unlock(vma); 1617 return -ENOMEM; 1618 } 1619 error = 0; 1620 1621 /* Somebody else might have raced and expanded it already */ 1622 if (address > vma->vm_end) { 1623 unsigned long size, grow; 1624 1625 size = address - vma->vm_start; 1626 grow = (address - vma->vm_end) >> PAGE_SHIFT; 1627 1628 error = acct_stack_growth(vma, size, grow); 1629 if (!error) 1630 vma->vm_end = address; 1631 } 1632 anon_vma_unlock(vma); 1633 return error; 1634} 1635#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 1636 1637/* 1638 * vma is the first one with address < vma->vm_start. Have to extend vma. 1639 */ 1640static int expand_downwards(struct vm_area_struct *vma, 1641 unsigned long address) 1642{ 1643 int error; 1644 1645 /* 1646 * We must make sure the anon_vma is allocated 1647 * so that the anon_vma locking is not a noop. 1648 */ 1649 if (unlikely(anon_vma_prepare(vma))) 1650 return -ENOMEM; 1651 1652 address &= PAGE_MASK; 1653 error = security_file_mmap(NULL, 0, 0, 0, address, 1); 1654 if (error) 1655 return error; 1656 1657 anon_vma_lock(vma); 1658 1659 /* 1660 * vma->vm_start/vm_end cannot change under us because the caller 1661 * is required to hold the mmap_sem in read mode. We need the 1662 * anon_vma lock to serialize against concurrent expand_stacks. 1663 */ 1664 1665 /* Somebody else might have raced and expanded it already */ 1666 if (address < vma->vm_start) { 1667 unsigned long size, grow; 1668 1669 size = vma->vm_end - address; 1670 grow = (vma->vm_start - address) >> PAGE_SHIFT; 1671 1672 error = acct_stack_growth(vma, size, grow); 1673 if (!error) { 1674 vma->vm_start = address; 1675 vma->vm_pgoff -= grow; 1676 } 1677 } 1678 anon_vma_unlock(vma); 1679 return error; 1680} 1681 1682int expand_stack_downwards(struct vm_area_struct *vma, unsigned long address) 1683{ 1684 return expand_downwards(vma, address); 1685} 1686 1687#ifdef CONFIG_STACK_GROWSUP 1688int expand_stack(struct vm_area_struct *vma, unsigned long address) 1689{ 1690 return expand_upwards(vma, address); 1691} 1692 1693struct vm_area_struct * 1694find_extend_vma(struct mm_struct *mm, unsigned long addr) 1695{ 1696 struct vm_area_struct *vma, *prev; 1697 1698 addr &= PAGE_MASK; 1699 vma = find_vma_prev(mm, addr, &prev); 1700 if (vma && (vma->vm_start <= addr)) 1701 return vma; 1702 if (!prev || expand_stack(prev, addr)) 1703 return NULL; 1704 if (prev->vm_flags & VM_LOCKED) { 1705 if (mlock_vma_pages_range(prev, addr, prev->vm_end) < 0) 1706 return NULL; /* vma gone! */ 1707 } 1708 return prev; 1709} 1710#else 1711int expand_stack(struct vm_area_struct *vma, unsigned long address) 1712{ 1713 return expand_downwards(vma, address); 1714} 1715 1716struct vm_area_struct * 1717find_extend_vma(struct mm_struct * mm, unsigned long addr) 1718{ 1719 struct vm_area_struct * vma; 1720 unsigned long start; 1721 1722 addr &= PAGE_MASK; 1723 vma = find_vma(mm,addr); 1724 if (!vma) 1725 return NULL; 1726 if (vma->vm_start <= addr) 1727 return vma; 1728 if (!(vma->vm_flags & VM_GROWSDOWN)) 1729 return NULL; 1730 start = vma->vm_start; 1731 if (expand_stack(vma, addr)) 1732 return NULL; 1733 if (vma->vm_flags & VM_LOCKED) { 1734 if (mlock_vma_pages_range(vma, addr, start) < 0) 1735 return NULL; /* vma gone! */ 1736 } 1737 return vma; 1738} 1739#endif 1740 1741/* 1742 * Ok - we have the memory areas we should free on the vma list, 1743 * so release them, and do the vma updates. 1744 * 1745 * Called with the mm semaphore held. 1746 */ 1747static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 1748{ 1749 /* Update high watermark before we lower total_vm */ 1750 update_hiwater_vm(mm); 1751 do { 1752 long nrpages = vma_pages(vma); 1753 1754 mm->total_vm -= nrpages; 1755 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 1756 vma = remove_vma(vma); 1757 } while (vma); 1758 validate_mm(mm); 1759} 1760 1761/* 1762 * Get rid of page table information in the indicated region. 1763 * 1764 * Called with the mm semaphore held. 1765 */ 1766static void unmap_region(struct mm_struct *mm, 1767 struct vm_area_struct *vma, struct vm_area_struct *prev, 1768 unsigned long start, unsigned long end) 1769{ 1770 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 1771 struct mmu_gather *tlb; 1772 unsigned long nr_accounted = 0; 1773 1774 lru_add_drain(); 1775 tlb = tlb_gather_mmu(mm, 0); 1776 update_hiwater_rss(mm); 1777 unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL); 1778 vm_unacct_memory(nr_accounted); 1779 free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS, 1780 next? next->vm_start: 0); 1781 tlb_finish_mmu(tlb, start, end); 1782} 1783 1784/* 1785 * Create a list of vma's touched by the unmap, removing them from the mm's 1786 * vma list as we go.. 1787 */ 1788static void 1789detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 1790 struct vm_area_struct *prev, unsigned long end) 1791{ 1792 struct vm_area_struct **insertion_point; 1793 struct vm_area_struct *tail_vma = NULL; 1794 unsigned long addr; 1795 1796 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 1797 do { 1798 rb_erase(&vma->vm_rb, &mm->mm_rb); 1799 mm->map_count--; 1800 tail_vma = vma; 1801 vma = vma->vm_next; 1802 } while (vma && vma->vm_start < end); 1803 *insertion_point = vma; 1804 tail_vma->vm_next = NULL; 1805 if (mm->unmap_area == arch_unmap_area) 1806 addr = prev ? prev->vm_end : mm->mmap_base; 1807 else 1808 addr = vma ? vma->vm_start : mm->mmap_base; 1809 mm->unmap_area(mm, addr); 1810 mm->mmap_cache = NULL; /* Kill the cache. */ 1811} 1812 1813/* 1814 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the 1815 * munmap path where it doesn't make sense to fail. 1816 */ 1817static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 1818 unsigned long addr, int new_below) 1819{ 1820 struct mempolicy *pol; 1821 struct vm_area_struct *new; 1822 1823 if (is_vm_hugetlb_page(vma) && (addr & 1824 ~(huge_page_mask(hstate_vma(vma))))) 1825 return -EINVAL; 1826 1827 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1828 if (!new) 1829 return -ENOMEM; 1830 1831 /* most fields are the same, copy all, and then fixup */ 1832 *new = *vma; 1833 1834 if (new_below) 1835 new->vm_end = addr; 1836 else { 1837 new->vm_start = addr; 1838 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 1839 } 1840 1841 pol = mpol_dup(vma_policy(vma)); 1842 if (IS_ERR(pol)) { 1843 kmem_cache_free(vm_area_cachep, new); 1844 return PTR_ERR(pol); 1845 } 1846 vma_set_policy(new, pol); 1847 1848 if (new->vm_file) { 1849 get_file(new->vm_file); 1850 if (vma->vm_flags & VM_EXECUTABLE) 1851 added_exe_file_vma(mm); 1852 } 1853 1854 if (new->vm_ops && new->vm_ops->open) 1855 new->vm_ops->open(new); 1856 1857 if (new_below) 1858 vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 1859 ((addr - new->vm_start) >> PAGE_SHIFT), new); 1860 else 1861 vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 1862 1863 return 0; 1864} 1865 1866/* 1867 * Split a vma into two pieces at address 'addr', a new vma is allocated 1868 * either for the first part or the tail. 1869 */ 1870int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 1871 unsigned long addr, int new_below) 1872{ 1873 if (mm->map_count >= sysctl_max_map_count) 1874 return -ENOMEM; 1875 1876 return __split_vma(mm, vma, addr, new_below); 1877} 1878 1879/* Munmap is split into 2 main parts -- this part which finds 1880 * what needs doing, and the areas themselves, which do the 1881 * work. This now handles partial unmappings. 1882 * Jeremy Fitzhardinge <jeremy@goop.org> 1883 */ 1884int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1885{ 1886 unsigned long end; 1887 struct vm_area_struct *vma, *prev, *last; 1888 1889 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 1890 return -EINVAL; 1891 1892 if ((len = PAGE_ALIGN(len)) == 0) 1893 return -EINVAL; 1894 1895 /* Find the first overlapping VMA */ 1896 vma = find_vma_prev(mm, start, &prev); 1897 if (!vma) 1898 return 0; 1899 /* we have start < vma->vm_end */ 1900 1901 /* if it doesn't overlap, we have nothing.. */ 1902 end = start + len; 1903 if (vma->vm_start >= end) 1904 return 0; 1905 1906 /* 1907 * If we need to split any vma, do it now to save pain later. 1908 * 1909 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 1910 * unmapped vm_area_struct will remain in use: so lower split_vma 1911 * places tmp vma above, and higher split_vma places tmp vma below. 1912 */ 1913 if (start > vma->vm_start) { 1914 int error; 1915 1916 /* 1917 * Make sure that map_count on return from munmap() will 1918 * not exceed its limit; but let map_count go just above 1919 * its limit temporarily, to help free resources as expected. 1920 */ 1921 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) 1922 return -ENOMEM; 1923 1924 error = __split_vma(mm, vma, start, 0); 1925 if (error) 1926 return error; 1927 prev = vma; 1928 } 1929 1930 /* Does it split the last one? */ 1931 last = find_vma(mm, end); 1932 if (last && end > last->vm_start) { 1933 int error = __split_vma(mm, last, end, 1); 1934 if (error) 1935 return error; 1936 } 1937 vma = prev? prev->vm_next: mm->mmap; 1938 1939 /* 1940 * unlock any mlock()ed ranges before detaching vmas 1941 */ 1942 if (mm->locked_vm) { 1943 struct vm_area_struct *tmp = vma; 1944 while (tmp && tmp->vm_start < end) { 1945 if (tmp->vm_flags & VM_LOCKED) { 1946 mm->locked_vm -= vma_pages(tmp); 1947 munlock_vma_pages_all(tmp); 1948 } 1949 tmp = tmp->vm_next; 1950 } 1951 } 1952 1953 /* 1954 * Remove the vma's, and unmap the actual pages 1955 */ 1956 detach_vmas_to_be_unmapped(mm, vma, prev, end); 1957 unmap_region(mm, vma, prev, start, end); 1958 1959 /* Fix up all other VM information */ 1960 remove_vma_list(mm, vma); 1961 1962 return 0; 1963} 1964 1965EXPORT_SYMBOL(do_munmap); 1966 1967SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1968{ 1969 int ret; 1970 struct mm_struct *mm = current->mm; 1971 1972 profile_munmap(addr); 1973 1974 down_write(&mm->mmap_sem); 1975 ret = do_munmap(mm, addr, len); 1976 up_write(&mm->mmap_sem); 1977 return ret; 1978} 1979 1980static inline void verify_mm_writelocked(struct mm_struct *mm) 1981{ 1982#ifdef CONFIG_DEBUG_VM 1983 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 1984 WARN_ON(1); 1985 up_read(&mm->mmap_sem); 1986 } 1987#endif 1988} 1989 1990/* 1991 * this is really a simplified "do_mmap". it only handles 1992 * anonymous maps. eventually we may be able to do some 1993 * brk-specific accounting here. 1994 */ 1995unsigned long do_brk(unsigned long addr, unsigned long len) 1996{ 1997 struct mm_struct * mm = current->mm; 1998 struct vm_area_struct * vma, * prev; 1999 unsigned long flags; 2000 struct rb_node ** rb_link, * rb_parent; 2001 pgoff_t pgoff = addr >> PAGE_SHIFT; 2002 int error; 2003 2004 len = PAGE_ALIGN(len); 2005 if (!len) 2006 return addr; 2007 2008 error = security_file_mmap(NULL, 0, 0, 0, addr, 1); 2009 if (error) 2010 return error; 2011 2012 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 2013 2014 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); 2015 if (error & ~PAGE_MASK) 2016 return error; 2017 2018 /* 2019 * mlock MCL_FUTURE? 2020 */ 2021 if (mm->def_flags & VM_LOCKED) { 2022 unsigned long locked, lock_limit; 2023 locked = len >> PAGE_SHIFT; 2024 locked += mm->locked_vm; 2025 lock_limit = current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur; 2026 lock_limit >>= PAGE_SHIFT; 2027 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 2028 return -EAGAIN; 2029 } 2030 2031 /* 2032 * mm->mmap_sem is required to protect against another thread 2033 * changing the mappings in case we sleep. 2034 */ 2035 verify_mm_writelocked(mm); 2036 2037 /* 2038 * Clear old maps. this also does some error checking for us 2039 */ 2040 munmap_back: 2041 vma = find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2042 if (vma && vma->vm_start < addr + len) { 2043 if (do_munmap(mm, addr, len)) 2044 return -ENOMEM; 2045 goto munmap_back; 2046 } 2047 2048 /* Check against address space limits *after* clearing old maps... */ 2049 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 2050 return -ENOMEM; 2051 2052 if (mm->map_count > sysctl_max_map_count) 2053 return -ENOMEM; 2054 2055 if (security_vm_enough_memory(len >> PAGE_SHIFT)) 2056 return -ENOMEM; 2057 2058 /* Can we just expand an old private anonymous mapping? */ 2059 vma = vma_merge(mm, prev, addr, addr + len, flags, 2060 NULL, NULL, pgoff, NULL); 2061 if (vma) 2062 goto out; 2063 2064 /* 2065 * create a vma struct for an anonymous mapping 2066 */ 2067 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2068 if (!vma) { 2069 vm_unacct_memory(len >> PAGE_SHIFT); 2070 return -ENOMEM; 2071 } 2072 2073 vma->vm_mm = mm; 2074 vma->vm_start = addr; 2075 vma->vm_end = addr + len; 2076 vma->vm_pgoff = pgoff; 2077 vma->vm_flags = flags; 2078 vma->vm_page_prot = vm_get_page_prot(flags); 2079 vma_link(mm, vma, prev, rb_link, rb_parent); 2080out: 2081 mm->total_vm += len >> PAGE_SHIFT; 2082 if (flags & VM_LOCKED) { 2083 if (!mlock_vma_pages_range(vma, addr, addr + len)) 2084 mm->locked_vm += (len >> PAGE_SHIFT); 2085 } 2086 return addr; 2087} 2088 2089EXPORT_SYMBOL(do_brk); 2090 2091/* Release all mmaps. */ 2092void exit_mmap(struct mm_struct *mm) 2093{ 2094 struct mmu_gather *tlb; 2095 struct vm_area_struct *vma; 2096 unsigned long nr_accounted = 0; 2097 unsigned long end; 2098 2099 /* mm's last user has gone, and its about to be pulled down */ 2100 mmu_notifier_release(mm); 2101 2102 if (mm->locked_vm) { 2103 vma = mm->mmap; 2104 while (vma) { 2105 if (vma->vm_flags & VM_LOCKED) 2106 munlock_vma_pages_all(vma); 2107 vma = vma->vm_next; 2108 } 2109 } 2110 2111 arch_exit_mmap(mm); 2112 2113 vma = mm->mmap; 2114 if (!vma) /* Can happen if dup_mmap() received an OOM */ 2115 return; 2116 2117 lru_add_drain(); 2118 flush_cache_mm(mm); 2119 tlb = tlb_gather_mmu(mm, 1); 2120 /* update_hiwater_rss(mm) here? but nobody should be looking */ 2121 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2122 end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL); 2123 vm_unacct_memory(nr_accounted); 2124 2125 free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0); 2126 tlb_finish_mmu(tlb, 0, end); 2127 2128 /* 2129 * Walk the list again, actually closing and freeing it, 2130 * with preemption enabled, without holding any MM locks. 2131 */ 2132 while (vma) 2133 vma = remove_vma(vma); 2134 2135 BUG_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2136} 2137 2138/* Insert vm structure into process list sorted by address 2139 * and into the inode's i_mmap tree. If vm_file is non-NULL 2140 * then i_mmap_lock is taken here. 2141 */ 2142int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma) 2143{ 2144 struct vm_area_struct * __vma, * prev; 2145 struct rb_node ** rb_link, * rb_parent; 2146 2147 /* 2148 * The vm_pgoff of a purely anonymous vma should be irrelevant 2149 * until its first write fault, when page's anon_vma and index 2150 * are set. But now set the vm_pgoff it will almost certainly 2151 * end up with (unless mremap moves it elsewhere before that 2152 * first wfault), so /proc/pid/maps tells a consistent story. 2153 * 2154 * By setting it to reflect the virtual start address of the 2155 * vma, merges and splits can happen in a seamless way, just 2156 * using the existing file pgoff checks and manipulations. 2157 * Similarly in do_mmap_pgoff and in do_brk. 2158 */ 2159 if (!vma->vm_file) { 2160 BUG_ON(vma->anon_vma); 2161 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2162 } 2163 __vma = find_vma_prepare(mm,vma->vm_start,&prev,&rb_link,&rb_parent); 2164 if (__vma && __vma->vm_start < vma->vm_end) 2165 return -ENOMEM; 2166 if ((vma->vm_flags & VM_ACCOUNT) && 2167 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2168 return -ENOMEM; 2169 vma_link(mm, vma, prev, rb_link, rb_parent); 2170 return 0; 2171} 2172 2173/* 2174 * Copy the vma structure to a new location in the same mm, 2175 * prior to moving page table entries, to effect an mremap move. 2176 */ 2177struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2178 unsigned long addr, unsigned long len, pgoff_t pgoff) 2179{ 2180 struct vm_area_struct *vma = *vmap; 2181 unsigned long vma_start = vma->vm_start; 2182 struct mm_struct *mm = vma->vm_mm; 2183 struct vm_area_struct *new_vma, *prev; 2184 struct rb_node **rb_link, *rb_parent; 2185 struct mempolicy *pol; 2186 2187 /* 2188 * If anonymous vma has not yet been faulted, update new pgoff 2189 * to match new location, to increase its chance of merging. 2190 */ 2191 if (!vma->vm_file && !vma->anon_vma) 2192 pgoff = addr >> PAGE_SHIFT; 2193 2194 find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent); 2195 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2196 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2197 if (new_vma) { 2198 /* 2199 * Source vma may have been merged into new_vma 2200 */ 2201 if (vma_start >= new_vma->vm_start && 2202 vma_start < new_vma->vm_end) 2203 *vmap = new_vma; 2204 } else { 2205 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2206 if (new_vma) { 2207 *new_vma = *vma; 2208 pol = mpol_dup(vma_policy(vma)); 2209 if (IS_ERR(pol)) { 2210 kmem_cache_free(vm_area_cachep, new_vma); 2211 return NULL; 2212 } 2213 vma_set_policy(new_vma, pol); 2214 new_vma->vm_start = addr; 2215 new_vma->vm_end = addr + len; 2216 new_vma->vm_pgoff = pgoff; 2217 if (new_vma->vm_file) { 2218 get_file(new_vma->vm_file); 2219 if (vma->vm_flags & VM_EXECUTABLE) 2220 added_exe_file_vma(mm); 2221 } 2222 if (new_vma->vm_ops && new_vma->vm_ops->open) 2223 new_vma->vm_ops->open(new_vma); 2224 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2225 } 2226 } 2227 return new_vma; 2228} 2229 2230/* 2231 * Return true if the calling process may expand its vm space by the passed 2232 * number of pages 2233 */ 2234int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2235{ 2236 unsigned long cur = mm->total_vm; /* pages */ 2237 unsigned long lim; 2238 2239 lim = current->signal->rlim[RLIMIT_AS].rlim_cur >> PAGE_SHIFT; 2240 2241 if (cur + npages > lim) 2242 return 0; 2243 return 1; 2244} 2245 2246 2247static int special_mapping_fault(struct vm_area_struct *vma, 2248 struct vm_fault *vmf) 2249{ 2250 pgoff_t pgoff; 2251 struct page **pages; 2252 2253 /* 2254 * special mappings have no vm_file, and in that case, the mm 2255 * uses vm_pgoff internally. So we have to subtract it from here. 2256 * We are allowed to do this because we are the mm; do not copy 2257 * this code into drivers! 2258 */ 2259 pgoff = vmf->pgoff - vma->vm_pgoff; 2260 2261 for (pages = vma->vm_private_data; pgoff && *pages; ++pages) 2262 pgoff--; 2263 2264 if (*pages) { 2265 struct page *page = *pages; 2266 get_page(page); 2267 vmf->page = page; 2268 return 0; 2269 } 2270 2271 return VM_FAULT_SIGBUS; 2272} 2273 2274/* 2275 * Having a close hook prevents vma merging regardless of flags. 2276 */ 2277static void special_mapping_close(struct vm_area_struct *vma) 2278{ 2279} 2280 2281static const struct vm_operations_struct special_mapping_vmops = { 2282 .close = special_mapping_close, 2283 .fault = special_mapping_fault, 2284}; 2285 2286/* 2287 * Called with mm->mmap_sem held for writing. 2288 * Insert a new vma covering the given region, with the given flags. 2289 * Its pages are supplied by the given array of struct page *. 2290 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2291 * The region past the last page supplied will always produce SIGBUS. 2292 * The array pointer and the pages it points to are assumed to stay alive 2293 * for as long as this mapping might exist. 2294 */ 2295int install_special_mapping(struct mm_struct *mm, 2296 unsigned long addr, unsigned long len, 2297 unsigned long vm_flags, struct page **pages) 2298{ 2299 struct vm_area_struct *vma; 2300 2301 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2302 if (unlikely(vma == NULL)) 2303 return -ENOMEM; 2304 2305 vma->vm_mm = mm; 2306 vma->vm_start = addr; 2307 vma->vm_end = addr + len; 2308 2309 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; 2310 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 2311 2312 vma->vm_ops = &special_mapping_vmops; 2313 vma->vm_private_data = pages; 2314 2315 if (unlikely(insert_vm_struct(mm, vma))) { 2316 kmem_cache_free(vm_area_cachep, vma); 2317 return -ENOMEM; 2318 } 2319 2320 mm->total_vm += len >> PAGE_SHIFT; 2321 2322 perf_event_mmap(vma); 2323 2324 return 0; 2325} 2326 2327static DEFINE_MUTEX(mm_all_locks_mutex); 2328 2329static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) 2330{ 2331 if (!test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2332 /* 2333 * The LSB of head.next can't change from under us 2334 * because we hold the mm_all_locks_mutex. 2335 */ 2336 spin_lock_nest_lock(&anon_vma->lock, &mm->mmap_sem); 2337 /* 2338 * We can safely modify head.next after taking the 2339 * anon_vma->lock. If some other vma in this mm shares 2340 * the same anon_vma we won't take it again. 2341 * 2342 * No need of atomic instructions here, head.next 2343 * can't change from under us thanks to the 2344 * anon_vma->lock. 2345 */ 2346 if (__test_and_set_bit(0, (unsigned long *) 2347 &anon_vma->head.next)) 2348 BUG(); 2349 } 2350} 2351 2352static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) 2353{ 2354 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2355 /* 2356 * AS_MM_ALL_LOCKS can't change from under us because 2357 * we hold the mm_all_locks_mutex. 2358 * 2359 * Operations on ->flags have to be atomic because 2360 * even if AS_MM_ALL_LOCKS is stable thanks to the 2361 * mm_all_locks_mutex, there may be other cpus 2362 * changing other bitflags in parallel to us. 2363 */ 2364 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) 2365 BUG(); 2366 spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem); 2367 } 2368} 2369 2370/* 2371 * This operation locks against the VM for all pte/vma/mm related 2372 * operations that could ever happen on a certain mm. This includes 2373 * vmtruncate, try_to_unmap, and all page faults. 2374 * 2375 * The caller must take the mmap_sem in write mode before calling 2376 * mm_take_all_locks(). The caller isn't allowed to release the 2377 * mmap_sem until mm_drop_all_locks() returns. 2378 * 2379 * mmap_sem in write mode is required in order to block all operations 2380 * that could modify pagetables and free pages without need of 2381 * altering the vma layout (for example populate_range() with 2382 * nonlinear vmas). It's also needed in write mode to avoid new 2383 * anon_vmas to be associated with existing vmas. 2384 * 2385 * A single task can't take more than one mm_take_all_locks() in a row 2386 * or it would deadlock. 2387 * 2388 * The LSB in anon_vma->head.next and the AS_MM_ALL_LOCKS bitflag in 2389 * mapping->flags avoid to take the same lock twice, if more than one 2390 * vma in this mm is backed by the same anon_vma or address_space. 2391 * 2392 * We can take all the locks in random order because the VM code 2393 * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never 2394 * takes more than one of them in a row. Secondly we're protected 2395 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. 2396 * 2397 * mm_take_all_locks() and mm_drop_all_locks are expensive operations 2398 * that may have to take thousand of locks. 2399 * 2400 * mm_take_all_locks() can fail if it's interrupted by signals. 2401 */ 2402int mm_take_all_locks(struct mm_struct *mm) 2403{ 2404 struct vm_area_struct *vma; 2405 int ret = -EINTR; 2406 2407 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2408 2409 mutex_lock(&mm_all_locks_mutex); 2410 2411 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2412 if (signal_pending(current)) 2413 goto out_unlock; 2414 if (vma->vm_file && vma->vm_file->f_mapping) 2415 vm_lock_mapping(mm, vma->vm_file->f_mapping); 2416 } 2417 2418 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2419 if (signal_pending(current)) 2420 goto out_unlock; 2421 if (vma->anon_vma) 2422 vm_lock_anon_vma(mm, vma->anon_vma); 2423 } 2424 2425 ret = 0; 2426 2427out_unlock: 2428 if (ret) 2429 mm_drop_all_locks(mm); 2430 2431 return ret; 2432} 2433 2434static void vm_unlock_anon_vma(struct anon_vma *anon_vma) 2435{ 2436 if (test_bit(0, (unsigned long *) &anon_vma->head.next)) { 2437 /* 2438 * The LSB of head.next can't change to 0 from under 2439 * us because we hold the mm_all_locks_mutex. 2440 * 2441 * We must however clear the bitflag before unlocking 2442 * the vma so the users using the anon_vma->head will 2443 * never see our bitflag. 2444 * 2445 * No need of atomic instructions here, head.next 2446 * can't change from under us until we release the 2447 * anon_vma->lock. 2448 */ 2449 if (!__test_and_clear_bit(0, (unsigned long *) 2450 &anon_vma->head.next)) 2451 BUG(); 2452 spin_unlock(&anon_vma->lock); 2453 } 2454} 2455 2456static void vm_unlock_mapping(struct address_space *mapping) 2457{ 2458 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2459 /* 2460 * AS_MM_ALL_LOCKS can't change to 0 from under us 2461 * because we hold the mm_all_locks_mutex. 2462 */ 2463 spin_unlock(&mapping->i_mmap_lock); 2464 if (!test_and_clear_bit(AS_MM_ALL_LOCKS, 2465 &mapping->flags)) 2466 BUG(); 2467 } 2468} 2469 2470/* 2471 * The mmap_sem cannot be released by the caller until 2472 * mm_drop_all_locks() returns. 2473 */ 2474void mm_drop_all_locks(struct mm_struct *mm) 2475{ 2476 struct vm_area_struct *vma; 2477 2478 BUG_ON(down_read_trylock(&mm->mmap_sem)); 2479 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); 2480 2481 for (vma = mm->mmap; vma; vma = vma->vm_next) { 2482 if (vma->anon_vma) 2483 vm_unlock_anon_vma(vma->anon_vma); 2484 if (vma->vm_file && vma->vm_file->f_mapping) 2485 vm_unlock_mapping(vma->vm_file->f_mapping); 2486 } 2487 2488 mutex_unlock(&mm_all_locks_mutex); 2489} 2490 2491/* 2492 * initialise the VMA slab 2493 */ 2494void __init mmap_init(void) 2495{ 2496 int ret; 2497 2498 ret = percpu_counter_init(&vm_committed_as, 0); 2499 VM_BUG_ON(ret); 2500} 2501