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/export.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 #include <linux/audit.h> 32 #include <linux/khugepaged.h> 33 #include <linux/uprobes.h> 34 #include <linux/rbtree_augmented.h> 35 #include <linux/sched/sysctl.h> 36 37 #include <asm/uaccess.h> 38 #include <asm/cacheflush.h> 39 #include <asm/tlb.h> 40 #include <asm/mmu_context.h> 41 42 #include "internal.h" 43 44 #ifndef arch_mmap_check 45 #define arch_mmap_check(addr, len, flags) (0) 46 #endif 47 48 #ifndef arch_rebalance_pgtables 49 #define arch_rebalance_pgtables(addr, len) (addr) 50 #endif 51 52 static void unmap_region(struct mm_struct *mm, 53 struct vm_area_struct *vma, struct vm_area_struct *prev, 54 unsigned long start, unsigned long end); 55 56 /* description of effects of mapping type and prot in current implementation. 57 * this is due to the limited x86 page protection hardware. The expected 58 * behavior is in parens: 59 * 60 * map_type prot 61 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 62 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 63 * w: (no) no w: (no) no w: (yes) yes w: (no) no 64 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 65 * 66 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 67 * w: (no) no w: (no) no w: (copy) copy w: (no) no 68 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 69 * 70 */ 71 pgprot_t protection_map[16] = { 72 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 73 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 74 }; 75 76 pgprot_t vm_get_page_prot(unsigned long vm_flags) 77 { 78 return __pgprot(pgprot_val(protection_map[vm_flags & 79 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | 80 pgprot_val(arch_vm_get_page_prot(vm_flags))); 81 } 82 EXPORT_SYMBOL(vm_get_page_prot); 83 84 int sysctl_overcommit_memory __read_mostly = OVERCOMMIT_GUESS; /* heuristic overcommit */ 85 int sysctl_overcommit_ratio __read_mostly = 50; /* default is 50% */ 86 int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT; 87 /* 88 * Make sure vm_committed_as in one cacheline and not cacheline shared with 89 * other variables. It can be updated by several CPUs frequently. 90 */ 91 struct percpu_counter vm_committed_as ____cacheline_aligned_in_smp; 92 93 /* 94 * The global memory commitment made in the system can be a metric 95 * that can be used to drive ballooning decisions when Linux is hosted 96 * as a guest. On Hyper-V, the host implements a policy engine for dynamically 97 * balancing memory across competing virtual machines that are hosted. 98 * Several metrics drive this policy engine including the guest reported 99 * memory commitment. 100 */ 101 unsigned long vm_memory_committed(void) 102 { 103 return percpu_counter_read_positive(&vm_committed_as); 104 } 105 EXPORT_SYMBOL_GPL(vm_memory_committed); 106 107 /* 108 * Check that a process has enough memory to allocate a new virtual 109 * mapping. 0 means there is enough memory for the allocation to 110 * succeed and -ENOMEM implies there is not. 111 * 112 * We currently support three overcommit policies, which are set via the 113 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 114 * 115 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 116 * Additional code 2002 Jul 20 by Robert Love. 117 * 118 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 119 * 120 * Note this is a helper function intended to be used by LSMs which 121 * wish to use this logic. 122 */ 123 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 124 { 125 unsigned long free, allowed; 126 127 vm_acct_memory(pages); 128 129 /* 130 * Sometimes we want to use more memory than we have 131 */ 132 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 133 return 0; 134 135 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 136 free = global_page_state(NR_FREE_PAGES); 137 free += global_page_state(NR_FILE_PAGES); 138 139 /* 140 * shmem pages shouldn't be counted as free in this 141 * case, they can't be purged, only swapped out, and 142 * that won't affect the overall amount of available 143 * memory in the system. 144 */ 145 free -= global_page_state(NR_SHMEM); 146 147 free += get_nr_swap_pages(); 148 149 /* 150 * Any slabs which are created with the 151 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 152 * which are reclaimable, under pressure. The dentry 153 * cache and most inode caches should fall into this 154 */ 155 free += global_page_state(NR_SLAB_RECLAIMABLE); 156 157 /* 158 * Leave reserved pages. The pages are not for anonymous pages. 159 */ 160 if (free <= totalreserve_pages) 161 goto error; 162 else 163 free -= totalreserve_pages; 164 165 /* 166 * Leave the last 3% for root 167 */ 168 if (!cap_sys_admin) 169 free -= free / 32; 170 171 if (free > pages) 172 return 0; 173 174 goto error; 175 } 176 177 allowed = (totalram_pages - hugetlb_total_pages()) 178 * sysctl_overcommit_ratio / 100; 179 /* 180 * Leave the last 3% for root 181 */ 182 if (!cap_sys_admin) 183 allowed -= allowed / 32; 184 allowed += total_swap_pages; 185 186 /* Don't let a single process grow too big: 187 leave 3% of the size of this process for other processes */ 188 if (mm) 189 allowed -= mm->total_vm / 32; 190 191 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 192 return 0; 193 error: 194 vm_unacct_memory(pages); 195 196 return -ENOMEM; 197 } 198 199 /* 200 * Requires inode->i_mapping->i_mmap_mutex 201 */ 202 static void __remove_shared_vm_struct(struct vm_area_struct *vma, 203 struct file *file, struct address_space *mapping) 204 { 205 if (vma->vm_flags & VM_DENYWRITE) 206 atomic_inc(&file_inode(file)->i_writecount); 207 if (vma->vm_flags & VM_SHARED) 208 mapping->i_mmap_writable--; 209 210 flush_dcache_mmap_lock(mapping); 211 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 212 list_del_init(&vma->shared.nonlinear); 213 else 214 vma_interval_tree_remove(vma, &mapping->i_mmap); 215 flush_dcache_mmap_unlock(mapping); 216 } 217 218 /* 219 * Unlink a file-based vm structure from its interval tree, to hide 220 * vma from rmap and vmtruncate before freeing its page tables. 221 */ 222 void unlink_file_vma(struct vm_area_struct *vma) 223 { 224 struct file *file = vma->vm_file; 225 226 if (file) { 227 struct address_space *mapping = file->f_mapping; 228 mutex_lock(&mapping->i_mmap_mutex); 229 __remove_shared_vm_struct(vma, file, mapping); 230 mutex_unlock(&mapping->i_mmap_mutex); 231 } 232 } 233 234 /* 235 * Close a vm structure and free it, returning the next. 236 */ 237 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 238 { 239 struct vm_area_struct *next = vma->vm_next; 240 241 might_sleep(); 242 if (vma->vm_ops && vma->vm_ops->close) 243 vma->vm_ops->close(vma); 244 if (vma->vm_file) 245 fput(vma->vm_file); 246 mpol_put(vma_policy(vma)); 247 kmem_cache_free(vm_area_cachep, vma); 248 return next; 249 } 250 251 static unsigned long do_brk(unsigned long addr, unsigned long len); 252 253 SYSCALL_DEFINE1(brk, unsigned long, brk) 254 { 255 unsigned long rlim, retval; 256 unsigned long newbrk, oldbrk; 257 struct mm_struct *mm = current->mm; 258 unsigned long min_brk; 259 bool populate; 260 261 down_write(&mm->mmap_sem); 262 263 #ifdef CONFIG_COMPAT_BRK 264 /* 265 * CONFIG_COMPAT_BRK can still be overridden by setting 266 * randomize_va_space to 2, which will still cause mm->start_brk 267 * to be arbitrarily shifted 268 */ 269 if (current->brk_randomized) 270 min_brk = mm->start_brk; 271 else 272 min_brk = mm->end_data; 273 #else 274 min_brk = mm->start_brk; 275 #endif 276 if (brk < min_brk) 277 goto out; 278 279 /* 280 * Check against rlimit here. If this check is done later after the test 281 * of oldbrk with newbrk then it can escape the test and let the data 282 * segment grow beyond its set limit the in case where the limit is 283 * not page aligned -Ram Gupta 284 */ 285 rlim = rlimit(RLIMIT_DATA); 286 if (rlim < RLIM_INFINITY && (brk - mm->start_brk) + 287 (mm->end_data - mm->start_data) > rlim) 288 goto out; 289 290 newbrk = PAGE_ALIGN(brk); 291 oldbrk = PAGE_ALIGN(mm->brk); 292 if (oldbrk == newbrk) 293 goto set_brk; 294 295 /* Always allow shrinking brk. */ 296 if (brk <= mm->brk) { 297 if (!do_munmap(mm, newbrk, oldbrk-newbrk)) 298 goto set_brk; 299 goto out; 300 } 301 302 /* Check against existing mmap mappings. */ 303 if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) 304 goto out; 305 306 /* Ok, looks good - let it rip. */ 307 if (do_brk(oldbrk, newbrk-oldbrk) != oldbrk) 308 goto out; 309 310 set_brk: 311 mm->brk = brk; 312 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; 313 up_write(&mm->mmap_sem); 314 if (populate) 315 mm_populate(oldbrk, newbrk - oldbrk); 316 return brk; 317 318 out: 319 retval = mm->brk; 320 up_write(&mm->mmap_sem); 321 return retval; 322 } 323 324 static long vma_compute_subtree_gap(struct vm_area_struct *vma) 325 { 326 unsigned long max, subtree_gap; 327 max = vma->vm_start; 328 if (vma->vm_prev) 329 max -= vma->vm_prev->vm_end; 330 if (vma->vm_rb.rb_left) { 331 subtree_gap = rb_entry(vma->vm_rb.rb_left, 332 struct vm_area_struct, vm_rb)->rb_subtree_gap; 333 if (subtree_gap > max) 334 max = subtree_gap; 335 } 336 if (vma->vm_rb.rb_right) { 337 subtree_gap = rb_entry(vma->vm_rb.rb_right, 338 struct vm_area_struct, vm_rb)->rb_subtree_gap; 339 if (subtree_gap > max) 340 max = subtree_gap; 341 } 342 return max; 343 } 344 345 #ifdef CONFIG_DEBUG_VM_RB 346 static int browse_rb(struct rb_root *root) 347 { 348 int i = 0, j, bug = 0; 349 struct rb_node *nd, *pn = NULL; 350 unsigned long prev = 0, pend = 0; 351 352 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 353 struct vm_area_struct *vma; 354 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 355 if (vma->vm_start < prev) { 356 printk("vm_start %lx prev %lx\n", vma->vm_start, prev); 357 bug = 1; 358 } 359 if (vma->vm_start < pend) { 360 printk("vm_start %lx pend %lx\n", vma->vm_start, pend); 361 bug = 1; 362 } 363 if (vma->vm_start > vma->vm_end) { 364 printk("vm_end %lx < vm_start %lx\n", 365 vma->vm_end, vma->vm_start); 366 bug = 1; 367 } 368 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { 369 printk("free gap %lx, correct %lx\n", 370 vma->rb_subtree_gap, 371 vma_compute_subtree_gap(vma)); 372 bug = 1; 373 } 374 i++; 375 pn = nd; 376 prev = vma->vm_start; 377 pend = vma->vm_end; 378 } 379 j = 0; 380 for (nd = pn; nd; nd = rb_prev(nd)) 381 j++; 382 if (i != j) { 383 printk("backwards %d, forwards %d\n", j, i); 384 bug = 1; 385 } 386 return bug ? -1 : i; 387 } 388 389 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) 390 { 391 struct rb_node *nd; 392 393 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 394 struct vm_area_struct *vma; 395 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 396 BUG_ON(vma != ignore && 397 vma->rb_subtree_gap != vma_compute_subtree_gap(vma)); 398 } 399 } 400 401 void validate_mm(struct mm_struct *mm) 402 { 403 int bug = 0; 404 int i = 0; 405 unsigned long highest_address = 0; 406 struct vm_area_struct *vma = mm->mmap; 407 while (vma) { 408 struct anon_vma_chain *avc; 409 vma_lock_anon_vma(vma); 410 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 411 anon_vma_interval_tree_verify(avc); 412 vma_unlock_anon_vma(vma); 413 highest_address = vma->vm_end; 414 vma = vma->vm_next; 415 i++; 416 } 417 if (i != mm->map_count) { 418 printk("map_count %d vm_next %d\n", mm->map_count, i); 419 bug = 1; 420 } 421 if (highest_address != mm->highest_vm_end) { 422 printk("mm->highest_vm_end %lx, found %lx\n", 423 mm->highest_vm_end, highest_address); 424 bug = 1; 425 } 426 i = browse_rb(&mm->mm_rb); 427 if (i != mm->map_count) { 428 printk("map_count %d rb %d\n", mm->map_count, i); 429 bug = 1; 430 } 431 BUG_ON(bug); 432 } 433 #else 434 #define validate_mm_rb(root, ignore) do { } while (0) 435 #define validate_mm(mm) do { } while (0) 436 #endif 437 438 RB_DECLARE_CALLBACKS(static, vma_gap_callbacks, struct vm_area_struct, vm_rb, 439 unsigned long, rb_subtree_gap, vma_compute_subtree_gap) 440 441 /* 442 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or 443 * vma->vm_prev->vm_end values changed, without modifying the vma's position 444 * in the rbtree. 445 */ 446 static void vma_gap_update(struct vm_area_struct *vma) 447 { 448 /* 449 * As it turns out, RB_DECLARE_CALLBACKS() already created a callback 450 * function that does exacltly what we want. 451 */ 452 vma_gap_callbacks_propagate(&vma->vm_rb, NULL); 453 } 454 455 static inline void vma_rb_insert(struct vm_area_struct *vma, 456 struct rb_root *root) 457 { 458 /* All rb_subtree_gap values must be consistent prior to insertion */ 459 validate_mm_rb(root, NULL); 460 461 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); 462 } 463 464 static void vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) 465 { 466 /* 467 * All rb_subtree_gap values must be consistent prior to erase, 468 * with the possible exception of the vma being erased. 469 */ 470 validate_mm_rb(root, vma); 471 472 /* 473 * Note rb_erase_augmented is a fairly large inline function, 474 * so make sure we instantiate it only once with our desired 475 * augmented rbtree callbacks. 476 */ 477 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); 478 } 479 480 /* 481 * vma has some anon_vma assigned, and is already inserted on that 482 * anon_vma's interval trees. 483 * 484 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the 485 * vma must be removed from the anon_vma's interval trees using 486 * anon_vma_interval_tree_pre_update_vma(). 487 * 488 * After the update, the vma will be reinserted using 489 * anon_vma_interval_tree_post_update_vma(). 490 * 491 * The entire update must be protected by exclusive mmap_sem and by 492 * the root anon_vma's mutex. 493 */ 494 static inline void 495 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) 496 { 497 struct anon_vma_chain *avc; 498 499 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 500 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); 501 } 502 503 static inline void 504 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) 505 { 506 struct anon_vma_chain *avc; 507 508 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 509 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); 510 } 511 512 static int find_vma_links(struct mm_struct *mm, unsigned long addr, 513 unsigned long end, struct vm_area_struct **pprev, 514 struct rb_node ***rb_link, struct rb_node **rb_parent) 515 { 516 struct rb_node **__rb_link, *__rb_parent, *rb_prev; 517 518 __rb_link = &mm->mm_rb.rb_node; 519 rb_prev = __rb_parent = NULL; 520 521 while (*__rb_link) { 522 struct vm_area_struct *vma_tmp; 523 524 __rb_parent = *__rb_link; 525 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 526 527 if (vma_tmp->vm_end > addr) { 528 /* Fail if an existing vma overlaps the area */ 529 if (vma_tmp->vm_start < end) 530 return -ENOMEM; 531 __rb_link = &__rb_parent->rb_left; 532 } else { 533 rb_prev = __rb_parent; 534 __rb_link = &__rb_parent->rb_right; 535 } 536 } 537 538 *pprev = NULL; 539 if (rb_prev) 540 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 541 *rb_link = __rb_link; 542 *rb_parent = __rb_parent; 543 return 0; 544 } 545 546 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 547 struct rb_node **rb_link, struct rb_node *rb_parent) 548 { 549 /* Update tracking information for the gap following the new vma. */ 550 if (vma->vm_next) 551 vma_gap_update(vma->vm_next); 552 else 553 mm->highest_vm_end = vma->vm_end; 554 555 /* 556 * vma->vm_prev wasn't known when we followed the rbtree to find the 557 * correct insertion point for that vma. As a result, we could not 558 * update the vma vm_rb parents rb_subtree_gap values on the way down. 559 * So, we first insert the vma with a zero rb_subtree_gap value 560 * (to be consistent with what we did on the way down), and then 561 * immediately update the gap to the correct value. Finally we 562 * rebalance the rbtree after all augmented values have been set. 563 */ 564 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 565 vma->rb_subtree_gap = 0; 566 vma_gap_update(vma); 567 vma_rb_insert(vma, &mm->mm_rb); 568 } 569 570 static void __vma_link_file(struct vm_area_struct *vma) 571 { 572 struct file *file; 573 574 file = vma->vm_file; 575 if (file) { 576 struct address_space *mapping = file->f_mapping; 577 578 if (vma->vm_flags & VM_DENYWRITE) 579 atomic_dec(&file_inode(file)->i_writecount); 580 if (vma->vm_flags & VM_SHARED) 581 mapping->i_mmap_writable++; 582 583 flush_dcache_mmap_lock(mapping); 584 if (unlikely(vma->vm_flags & VM_NONLINEAR)) 585 vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear); 586 else 587 vma_interval_tree_insert(vma, &mapping->i_mmap); 588 flush_dcache_mmap_unlock(mapping); 589 } 590 } 591 592 static void 593 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 594 struct vm_area_struct *prev, struct rb_node **rb_link, 595 struct rb_node *rb_parent) 596 { 597 __vma_link_list(mm, vma, prev, rb_parent); 598 __vma_link_rb(mm, vma, rb_link, rb_parent); 599 } 600 601 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 602 struct vm_area_struct *prev, struct rb_node **rb_link, 603 struct rb_node *rb_parent) 604 { 605 struct address_space *mapping = NULL; 606 607 if (vma->vm_file) 608 mapping = vma->vm_file->f_mapping; 609 610 if (mapping) 611 mutex_lock(&mapping->i_mmap_mutex); 612 613 __vma_link(mm, vma, prev, rb_link, rb_parent); 614 __vma_link_file(vma); 615 616 if (mapping) 617 mutex_unlock(&mapping->i_mmap_mutex); 618 619 mm->map_count++; 620 validate_mm(mm); 621 } 622 623 /* 624 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the 625 * mm's list and rbtree. It has already been inserted into the interval tree. 626 */ 627 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 628 { 629 struct vm_area_struct *prev; 630 struct rb_node **rb_link, *rb_parent; 631 632 if (find_vma_links(mm, vma->vm_start, vma->vm_end, 633 &prev, &rb_link, &rb_parent)) 634 BUG(); 635 __vma_link(mm, vma, prev, rb_link, rb_parent); 636 mm->map_count++; 637 } 638 639 static inline void 640 __vma_unlink(struct mm_struct *mm, struct vm_area_struct *vma, 641 struct vm_area_struct *prev) 642 { 643 struct vm_area_struct *next; 644 645 vma_rb_erase(vma, &mm->mm_rb); 646 prev->vm_next = next = vma->vm_next; 647 if (next) 648 next->vm_prev = prev; 649 if (mm->mmap_cache == vma) 650 mm->mmap_cache = prev; 651 } 652 653 /* 654 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 655 * is already present in an i_mmap tree without adjusting the tree. 656 * The following helper function should be used when such adjustments 657 * are necessary. The "insert" vma (if any) is to be inserted 658 * before we drop the necessary locks. 659 */ 660 int vma_adjust(struct vm_area_struct *vma, unsigned long start, 661 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert) 662 { 663 struct mm_struct *mm = vma->vm_mm; 664 struct vm_area_struct *next = vma->vm_next; 665 struct vm_area_struct *importer = NULL; 666 struct address_space *mapping = NULL; 667 struct rb_root *root = NULL; 668 struct anon_vma *anon_vma = NULL; 669 struct file *file = vma->vm_file; 670 bool start_changed = false, end_changed = false; 671 long adjust_next = 0; 672 int remove_next = 0; 673 674 if (next && !insert) { 675 struct vm_area_struct *exporter = NULL; 676 677 if (end >= next->vm_end) { 678 /* 679 * vma expands, overlapping all the next, and 680 * perhaps the one after too (mprotect case 6). 681 */ 682 again: remove_next = 1 + (end > next->vm_end); 683 end = next->vm_end; 684 exporter = next; 685 importer = vma; 686 } else if (end > next->vm_start) { 687 /* 688 * vma expands, overlapping part of the next: 689 * mprotect case 5 shifting the boundary up. 690 */ 691 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 692 exporter = next; 693 importer = vma; 694 } else if (end < vma->vm_end) { 695 /* 696 * vma shrinks, and !insert tells it's not 697 * split_vma inserting another: so it must be 698 * mprotect case 4 shifting the boundary down. 699 */ 700 adjust_next = - ((vma->vm_end - end) >> PAGE_SHIFT); 701 exporter = vma; 702 importer = next; 703 } 704 705 /* 706 * Easily overlooked: when mprotect shifts the boundary, 707 * make sure the expanding vma has anon_vma set if the 708 * shrinking vma had, to cover any anon pages imported. 709 */ 710 if (exporter && exporter->anon_vma && !importer->anon_vma) { 711 if (anon_vma_clone(importer, exporter)) 712 return -ENOMEM; 713 importer->anon_vma = exporter->anon_vma; 714 } 715 } 716 717 if (file) { 718 mapping = file->f_mapping; 719 if (!(vma->vm_flags & VM_NONLINEAR)) { 720 root = &mapping->i_mmap; 721 uprobe_munmap(vma, vma->vm_start, vma->vm_end); 722 723 if (adjust_next) 724 uprobe_munmap(next, next->vm_start, 725 next->vm_end); 726 } 727 728 mutex_lock(&mapping->i_mmap_mutex); 729 if (insert) { 730 /* 731 * Put into interval tree now, so instantiated pages 732 * are visible to arm/parisc __flush_dcache_page 733 * throughout; but we cannot insert into address 734 * space until vma start or end is updated. 735 */ 736 __vma_link_file(insert); 737 } 738 } 739 740 vma_adjust_trans_huge(vma, start, end, adjust_next); 741 742 anon_vma = vma->anon_vma; 743 if (!anon_vma && adjust_next) 744 anon_vma = next->anon_vma; 745 if (anon_vma) { 746 VM_BUG_ON(adjust_next && next->anon_vma && 747 anon_vma != next->anon_vma); 748 anon_vma_lock_write(anon_vma); 749 anon_vma_interval_tree_pre_update_vma(vma); 750 if (adjust_next) 751 anon_vma_interval_tree_pre_update_vma(next); 752 } 753 754 if (root) { 755 flush_dcache_mmap_lock(mapping); 756 vma_interval_tree_remove(vma, root); 757 if (adjust_next) 758 vma_interval_tree_remove(next, root); 759 } 760 761 if (start != vma->vm_start) { 762 vma->vm_start = start; 763 start_changed = true; 764 } 765 if (end != vma->vm_end) { 766 vma->vm_end = end; 767 end_changed = true; 768 } 769 vma->vm_pgoff = pgoff; 770 if (adjust_next) { 771 next->vm_start += adjust_next << PAGE_SHIFT; 772 next->vm_pgoff += adjust_next; 773 } 774 775 if (root) { 776 if (adjust_next) 777 vma_interval_tree_insert(next, root); 778 vma_interval_tree_insert(vma, root); 779 flush_dcache_mmap_unlock(mapping); 780 } 781 782 if (remove_next) { 783 /* 784 * vma_merge has merged next into vma, and needs 785 * us to remove next before dropping the locks. 786 */ 787 __vma_unlink(mm, next, vma); 788 if (file) 789 __remove_shared_vm_struct(next, file, mapping); 790 } else if (insert) { 791 /* 792 * split_vma has split insert from vma, and needs 793 * us to insert it before dropping the locks 794 * (it may either follow vma or precede it). 795 */ 796 __insert_vm_struct(mm, insert); 797 } else { 798 if (start_changed) 799 vma_gap_update(vma); 800 if (end_changed) { 801 if (!next) 802 mm->highest_vm_end = end; 803 else if (!adjust_next) 804 vma_gap_update(next); 805 } 806 } 807 808 if (anon_vma) { 809 anon_vma_interval_tree_post_update_vma(vma); 810 if (adjust_next) 811 anon_vma_interval_tree_post_update_vma(next); 812 anon_vma_unlock_write(anon_vma); 813 } 814 if (mapping) 815 mutex_unlock(&mapping->i_mmap_mutex); 816 817 if (root) { 818 uprobe_mmap(vma); 819 820 if (adjust_next) 821 uprobe_mmap(next); 822 } 823 824 if (remove_next) { 825 if (file) { 826 uprobe_munmap(next, next->vm_start, next->vm_end); 827 fput(file); 828 } 829 if (next->anon_vma) 830 anon_vma_merge(vma, next); 831 mm->map_count--; 832 mpol_put(vma_policy(next)); 833 kmem_cache_free(vm_area_cachep, next); 834 /* 835 * In mprotect's case 6 (see comments on vma_merge), 836 * we must remove another next too. It would clutter 837 * up the code too much to do both in one go. 838 */ 839 next = vma->vm_next; 840 if (remove_next == 2) 841 goto again; 842 else if (next) 843 vma_gap_update(next); 844 else 845 mm->highest_vm_end = end; 846 } 847 if (insert && file) 848 uprobe_mmap(insert); 849 850 validate_mm(mm); 851 852 return 0; 853 } 854 855 /* 856 * If the vma has a ->close operation then the driver probably needs to release 857 * per-vma resources, so we don't attempt to merge those. 858 */ 859 static inline int is_mergeable_vma(struct vm_area_struct *vma, 860 struct file *file, unsigned long vm_flags) 861 { 862 if (vma->vm_flags ^ vm_flags) 863 return 0; 864 if (vma->vm_file != file) 865 return 0; 866 if (vma->vm_ops && vma->vm_ops->close) 867 return 0; 868 return 1; 869 } 870 871 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 872 struct anon_vma *anon_vma2, 873 struct vm_area_struct *vma) 874 { 875 /* 876 * The list_is_singular() test is to avoid merging VMA cloned from 877 * parents. This can improve scalability caused by anon_vma lock. 878 */ 879 if ((!anon_vma1 || !anon_vma2) && (!vma || 880 list_is_singular(&vma->anon_vma_chain))) 881 return 1; 882 return anon_vma1 == anon_vma2; 883 } 884 885 /* 886 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 887 * in front of (at a lower virtual address and file offset than) the vma. 888 * 889 * We cannot merge two vmas if they have differently assigned (non-NULL) 890 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 891 * 892 * We don't check here for the merged mmap wrapping around the end of pagecache 893 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 894 * wrap, nor mmaps which cover the final page at index -1UL. 895 */ 896 static int 897 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 898 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 899 { 900 if (is_mergeable_vma(vma, file, vm_flags) && 901 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { 902 if (vma->vm_pgoff == vm_pgoff) 903 return 1; 904 } 905 return 0; 906 } 907 908 /* 909 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 910 * beyond (at a higher virtual address and file offset than) the vma. 911 * 912 * We cannot merge two vmas if they have differently assigned (non-NULL) 913 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 914 */ 915 static int 916 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 917 struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff) 918 { 919 if (is_mergeable_vma(vma, file, vm_flags) && 920 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { 921 pgoff_t vm_pglen; 922 vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 923 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 924 return 1; 925 } 926 return 0; 927 } 928 929 /* 930 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 931 * whether that can be merged with its predecessor or its successor. 932 * Or both (it neatly fills a hole). 933 * 934 * In most cases - when called for mmap, brk or mremap - [addr,end) is 935 * certain not to be mapped by the time vma_merge is called; but when 936 * called for mprotect, it is certain to be already mapped (either at 937 * an offset within prev, or at the start of next), and the flags of 938 * this area are about to be changed to vm_flags - and the no-change 939 * case has already been eliminated. 940 * 941 * The following mprotect cases have to be considered, where AAAA is 942 * the area passed down from mprotect_fixup, never extending beyond one 943 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 944 * 945 * AAAA AAAA AAAA AAAA 946 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN PPPPNNNNXXXX 947 * cannot merge might become might become might become 948 * PPNNNNNNNNNN PPPPPPPPPPNN PPPPPPPPPPPP 6 or 949 * mmap, brk or case 4 below case 5 below PPPPPPPPXXXX 7 or 950 * mremap move: PPPPNNNNNNNN 8 951 * AAAA 952 * PPPP NNNN PPPPPPPPPPPP PPPPPPPPNNNN PPPPNNNNNNNN 953 * might become case 1 below case 2 below case 3 below 954 * 955 * Odd one out? Case 8, because it extends NNNN but needs flags of XXXX: 956 * mprotect_fixup updates vm_flags & vm_page_prot on successful return. 957 */ 958 struct vm_area_struct *vma_merge(struct mm_struct *mm, 959 struct vm_area_struct *prev, unsigned long addr, 960 unsigned long end, unsigned long vm_flags, 961 struct anon_vma *anon_vma, struct file *file, 962 pgoff_t pgoff, struct mempolicy *policy) 963 { 964 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 965 struct vm_area_struct *area, *next; 966 int err; 967 968 /* 969 * We later require that vma->vm_flags == vm_flags, 970 * so this tests vma->vm_flags & VM_SPECIAL, too. 971 */ 972 if (vm_flags & VM_SPECIAL) 973 return NULL; 974 975 if (prev) 976 next = prev->vm_next; 977 else 978 next = mm->mmap; 979 area = next; 980 if (next && next->vm_end == end) /* cases 6, 7, 8 */ 981 next = next->vm_next; 982 983 /* 984 * Can it merge with the predecessor? 985 */ 986 if (prev && prev->vm_end == addr && 987 mpol_equal(vma_policy(prev), policy) && 988 can_vma_merge_after(prev, vm_flags, 989 anon_vma, file, pgoff)) { 990 /* 991 * OK, it can. Can we now merge in the successor as well? 992 */ 993 if (next && end == next->vm_start && 994 mpol_equal(policy, vma_policy(next)) && 995 can_vma_merge_before(next, vm_flags, 996 anon_vma, file, pgoff+pglen) && 997 is_mergeable_anon_vma(prev->anon_vma, 998 next->anon_vma, NULL)) { 999 /* cases 1, 6 */ 1000 err = vma_adjust(prev, prev->vm_start, 1001 next->vm_end, prev->vm_pgoff, NULL); 1002 } else /* cases 2, 5, 7 */ 1003 err = vma_adjust(prev, prev->vm_start, 1004 end, prev->vm_pgoff, NULL); 1005 if (err) 1006 return NULL; 1007 khugepaged_enter_vma_merge(prev); 1008 return prev; 1009 } 1010 1011 /* 1012 * Can this new request be merged in front of next? 1013 */ 1014 if (next && end == next->vm_start && 1015 mpol_equal(policy, vma_policy(next)) && 1016 can_vma_merge_before(next, vm_flags, 1017 anon_vma, file, pgoff+pglen)) { 1018 if (prev && addr < prev->vm_end) /* case 4 */ 1019 err = vma_adjust(prev, prev->vm_start, 1020 addr, prev->vm_pgoff, NULL); 1021 else /* cases 3, 8 */ 1022 err = vma_adjust(area, addr, next->vm_end, 1023 next->vm_pgoff - pglen, NULL); 1024 if (err) 1025 return NULL; 1026 khugepaged_enter_vma_merge(area); 1027 return area; 1028 } 1029 1030 return NULL; 1031 } 1032 1033 /* 1034 * Rough compatbility check to quickly see if it's even worth looking 1035 * at sharing an anon_vma. 1036 * 1037 * They need to have the same vm_file, and the flags can only differ 1038 * in things that mprotect may change. 1039 * 1040 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that 1041 * we can merge the two vma's. For example, we refuse to merge a vma if 1042 * there is a vm_ops->close() function, because that indicates that the 1043 * driver is doing some kind of reference counting. But that doesn't 1044 * really matter for the anon_vma sharing case. 1045 */ 1046 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) 1047 { 1048 return a->vm_end == b->vm_start && 1049 mpol_equal(vma_policy(a), vma_policy(b)) && 1050 a->vm_file == b->vm_file && 1051 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC)) && 1052 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); 1053 } 1054 1055 /* 1056 * Do some basic sanity checking to see if we can re-use the anon_vma 1057 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be 1058 * the same as 'old', the other will be the new one that is trying 1059 * to share the anon_vma. 1060 * 1061 * NOTE! This runs with mm_sem held for reading, so it is possible that 1062 * the anon_vma of 'old' is concurrently in the process of being set up 1063 * by another page fault trying to merge _that_. But that's ok: if it 1064 * is being set up, that automatically means that it will be a singleton 1065 * acceptable for merging, so we can do all of this optimistically. But 1066 * we do that ACCESS_ONCE() to make sure that we never re-load the pointer. 1067 * 1068 * IOW: that the "list_is_singular()" test on the anon_vma_chain only 1069 * matters for the 'stable anon_vma' case (ie the thing we want to avoid 1070 * is to return an anon_vma that is "complex" due to having gone through 1071 * a fork). 1072 * 1073 * We also make sure that the two vma's are compatible (adjacent, 1074 * and with the same memory policies). That's all stable, even with just 1075 * a read lock on the mm_sem. 1076 */ 1077 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) 1078 { 1079 if (anon_vma_compatible(a, b)) { 1080 struct anon_vma *anon_vma = ACCESS_ONCE(old->anon_vma); 1081 1082 if (anon_vma && list_is_singular(&old->anon_vma_chain)) 1083 return anon_vma; 1084 } 1085 return NULL; 1086 } 1087 1088 /* 1089 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 1090 * neighbouring vmas for a suitable anon_vma, before it goes off 1091 * to allocate a new anon_vma. It checks because a repetitive 1092 * sequence of mprotects and faults may otherwise lead to distinct 1093 * anon_vmas being allocated, preventing vma merge in subsequent 1094 * mprotect. 1095 */ 1096 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 1097 { 1098 struct anon_vma *anon_vma; 1099 struct vm_area_struct *near; 1100 1101 near = vma->vm_next; 1102 if (!near) 1103 goto try_prev; 1104 1105 anon_vma = reusable_anon_vma(near, vma, near); 1106 if (anon_vma) 1107 return anon_vma; 1108 try_prev: 1109 near = vma->vm_prev; 1110 if (!near) 1111 goto none; 1112 1113 anon_vma = reusable_anon_vma(near, near, vma); 1114 if (anon_vma) 1115 return anon_vma; 1116 none: 1117 /* 1118 * There's no absolute need to look only at touching neighbours: 1119 * we could search further afield for "compatible" anon_vmas. 1120 * But it would probably just be a waste of time searching, 1121 * or lead to too many vmas hanging off the same anon_vma. 1122 * We're trying to allow mprotect remerging later on, 1123 * not trying to minimize memory used for anon_vmas. 1124 */ 1125 return NULL; 1126 } 1127 1128 #ifdef CONFIG_PROC_FS 1129 void vm_stat_account(struct mm_struct *mm, unsigned long flags, 1130 struct file *file, long pages) 1131 { 1132 const unsigned long stack_flags 1133 = VM_STACK_FLAGS & (VM_GROWSUP|VM_GROWSDOWN); 1134 1135 mm->total_vm += pages; 1136 1137 if (file) { 1138 mm->shared_vm += pages; 1139 if ((flags & (VM_EXEC|VM_WRITE)) == VM_EXEC) 1140 mm->exec_vm += pages; 1141 } else if (flags & stack_flags) 1142 mm->stack_vm += pages; 1143 } 1144 #endif /* CONFIG_PROC_FS */ 1145 1146 /* 1147 * If a hint addr is less than mmap_min_addr change hint to be as 1148 * low as possible but still greater than mmap_min_addr 1149 */ 1150 static inline unsigned long round_hint_to_min(unsigned long hint) 1151 { 1152 hint &= PAGE_MASK; 1153 if (((void *)hint != NULL) && 1154 (hint < mmap_min_addr)) 1155 return PAGE_ALIGN(mmap_min_addr); 1156 return hint; 1157 } 1158 1159 /* 1160 * The caller must hold down_write(¤t->mm->mmap_sem). 1161 */ 1162 1163 unsigned long do_mmap_pgoff(struct file *file, unsigned long addr, 1164 unsigned long len, unsigned long prot, 1165 unsigned long flags, unsigned long pgoff, 1166 unsigned long *populate) 1167 { 1168 struct mm_struct * mm = current->mm; 1169 struct inode *inode; 1170 vm_flags_t vm_flags; 1171 1172 *populate = 0; 1173 1174 /* 1175 * Does the application expect PROT_READ to imply PROT_EXEC? 1176 * 1177 * (the exception is when the underlying filesystem is noexec 1178 * mounted, in which case we dont add PROT_EXEC.) 1179 */ 1180 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 1181 if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC))) 1182 prot |= PROT_EXEC; 1183 1184 if (!len) 1185 return -EINVAL; 1186 1187 if (!(flags & MAP_FIXED)) 1188 addr = round_hint_to_min(addr); 1189 1190 /* Careful about overflows.. */ 1191 len = PAGE_ALIGN(len); 1192 if (!len) 1193 return -ENOMEM; 1194 1195 /* offset overflow? */ 1196 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 1197 return -EOVERFLOW; 1198 1199 /* Too many mappings? */ 1200 if (mm->map_count > sysctl_max_map_count) 1201 return -ENOMEM; 1202 1203 /* Obtain the address to map to. we verify (or select) it and ensure 1204 * that it represents a valid section of the address space. 1205 */ 1206 addr = get_unmapped_area(file, addr, len, pgoff, flags); 1207 if (addr & ~PAGE_MASK) 1208 return addr; 1209 1210 /* Do simple checking here so the lower-level routines won't have 1211 * to. we assume access permissions have been handled by the open 1212 * of the memory object, so we don't do any here. 1213 */ 1214 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags) | 1215 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1216 1217 if (flags & MAP_LOCKED) 1218 if (!can_do_mlock()) 1219 return -EPERM; 1220 1221 /* mlock MCL_FUTURE? */ 1222 if (vm_flags & VM_LOCKED) { 1223 unsigned long locked, lock_limit; 1224 locked = len >> PAGE_SHIFT; 1225 locked += mm->locked_vm; 1226 lock_limit = rlimit(RLIMIT_MEMLOCK); 1227 lock_limit >>= PAGE_SHIFT; 1228 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1229 return -EAGAIN; 1230 } 1231 1232 inode = file ? file_inode(file) : NULL; 1233 1234 if (file) { 1235 switch (flags & MAP_TYPE) { 1236 case MAP_SHARED: 1237 if ((prot&PROT_WRITE) && !(file->f_mode&FMODE_WRITE)) 1238 return -EACCES; 1239 1240 /* 1241 * Make sure we don't allow writing to an append-only 1242 * file.. 1243 */ 1244 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 1245 return -EACCES; 1246 1247 /* 1248 * Make sure there are no mandatory locks on the file. 1249 */ 1250 if (locks_verify_locked(inode)) 1251 return -EAGAIN; 1252 1253 vm_flags |= VM_SHARED | VM_MAYSHARE; 1254 if (!(file->f_mode & FMODE_WRITE)) 1255 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1256 1257 /* fall through */ 1258 case MAP_PRIVATE: 1259 if (!(file->f_mode & FMODE_READ)) 1260 return -EACCES; 1261 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1262 if (vm_flags & VM_EXEC) 1263 return -EPERM; 1264 vm_flags &= ~VM_MAYEXEC; 1265 } 1266 1267 if (!file->f_op || !file->f_op->mmap) 1268 return -ENODEV; 1269 break; 1270 1271 default: 1272 return -EINVAL; 1273 } 1274 } else { 1275 switch (flags & MAP_TYPE) { 1276 case MAP_SHARED: 1277 /* 1278 * Ignore pgoff. 1279 */ 1280 pgoff = 0; 1281 vm_flags |= VM_SHARED | VM_MAYSHARE; 1282 break; 1283 case MAP_PRIVATE: 1284 /* 1285 * Set pgoff according to addr for anon_vma. 1286 */ 1287 pgoff = addr >> PAGE_SHIFT; 1288 break; 1289 default: 1290 return -EINVAL; 1291 } 1292 } 1293 1294 /* 1295 * Set 'VM_NORESERVE' if we should not account for the 1296 * memory use of this mapping. 1297 */ 1298 if (flags & MAP_NORESERVE) { 1299 /* We honor MAP_NORESERVE if allowed to overcommit */ 1300 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) 1301 vm_flags |= VM_NORESERVE; 1302 1303 /* hugetlb applies strict overcommit unless MAP_NORESERVE */ 1304 if (file && is_file_hugepages(file)) 1305 vm_flags |= VM_NORESERVE; 1306 } 1307 1308 addr = mmap_region(file, addr, len, vm_flags, pgoff); 1309 if (!IS_ERR_VALUE(addr) && 1310 ((vm_flags & VM_LOCKED) || 1311 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) 1312 *populate = len; 1313 return addr; 1314 } 1315 1316 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1317 unsigned long, prot, unsigned long, flags, 1318 unsigned long, fd, unsigned long, pgoff) 1319 { 1320 struct file *file = NULL; 1321 unsigned long retval = -EBADF; 1322 1323 if (!(flags & MAP_ANONYMOUS)) { 1324 audit_mmap_fd(fd, flags); 1325 if (unlikely(flags & MAP_HUGETLB)) 1326 return -EINVAL; 1327 file = fget(fd); 1328 if (!file) 1329 goto out; 1330 } else if (flags & MAP_HUGETLB) { 1331 struct user_struct *user = NULL; 1332 /* 1333 * VM_NORESERVE is used because the reservations will be 1334 * taken when vm_ops->mmap() is called 1335 * A dummy user value is used because we are not locking 1336 * memory so no accounting is necessary 1337 */ 1338 file = hugetlb_file_setup(HUGETLB_ANON_FILE, addr, len, 1339 VM_NORESERVE, 1340 &user, HUGETLB_ANONHUGE_INODE, 1341 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); 1342 if (IS_ERR(file)) 1343 return PTR_ERR(file); 1344 } 1345 1346 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1347 1348 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1349 if (file) 1350 fput(file); 1351 out: 1352 return retval; 1353 } 1354 1355 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1356 struct mmap_arg_struct { 1357 unsigned long addr; 1358 unsigned long len; 1359 unsigned long prot; 1360 unsigned long flags; 1361 unsigned long fd; 1362 unsigned long offset; 1363 }; 1364 1365 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1366 { 1367 struct mmap_arg_struct a; 1368 1369 if (copy_from_user(&a, arg, sizeof(a))) 1370 return -EFAULT; 1371 if (a.offset & ~PAGE_MASK) 1372 return -EINVAL; 1373 1374 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1375 a.offset >> PAGE_SHIFT); 1376 } 1377 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1378 1379 /* 1380 * Some shared mappigns will want the pages marked read-only 1381 * to track write events. If so, we'll downgrade vm_page_prot 1382 * to the private version (using protection_map[] without the 1383 * VM_SHARED bit). 1384 */ 1385 int vma_wants_writenotify(struct vm_area_struct *vma) 1386 { 1387 vm_flags_t vm_flags = vma->vm_flags; 1388 1389 /* If it was private or non-writable, the write bit is already clear */ 1390 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1391 return 0; 1392 1393 /* The backer wishes to know when pages are first written to? */ 1394 if (vma->vm_ops && vma->vm_ops->page_mkwrite) 1395 return 1; 1396 1397 /* The open routine did something to the protections already? */ 1398 if (pgprot_val(vma->vm_page_prot) != 1399 pgprot_val(vm_get_page_prot(vm_flags))) 1400 return 0; 1401 1402 /* Specialty mapping? */ 1403 if (vm_flags & VM_PFNMAP) 1404 return 0; 1405 1406 /* Can the mapping track the dirty pages? */ 1407 return vma->vm_file && vma->vm_file->f_mapping && 1408 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1409 } 1410 1411 /* 1412 * We account for memory if it's a private writeable mapping, 1413 * not hugepages and VM_NORESERVE wasn't set. 1414 */ 1415 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) 1416 { 1417 /* 1418 * hugetlb has its own accounting separate from the core VM 1419 * VM_HUGETLB may not be set yet so we cannot check for that flag. 1420 */ 1421 if (file && is_file_hugepages(file)) 1422 return 0; 1423 1424 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; 1425 } 1426 1427 unsigned long mmap_region(struct file *file, unsigned long addr, 1428 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff) 1429 { 1430 struct mm_struct *mm = current->mm; 1431 struct vm_area_struct *vma, *prev; 1432 int correct_wcount = 0; 1433 int error; 1434 struct rb_node **rb_link, *rb_parent; 1435 unsigned long charged = 0; 1436 struct inode *inode = file ? file_inode(file) : NULL; 1437 1438 /* Clear old maps */ 1439 error = -ENOMEM; 1440 munmap_back: 1441 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) { 1442 if (do_munmap(mm, addr, len)) 1443 return -ENOMEM; 1444 goto munmap_back; 1445 } 1446 1447 /* Check against address space limit. */ 1448 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 1449 return -ENOMEM; 1450 1451 /* 1452 * Private writable mapping: check memory availability 1453 */ 1454 if (accountable_mapping(file, vm_flags)) { 1455 charged = len >> PAGE_SHIFT; 1456 if (security_vm_enough_memory_mm(mm, charged)) 1457 return -ENOMEM; 1458 vm_flags |= VM_ACCOUNT; 1459 } 1460 1461 /* 1462 * Can we just expand an old mapping? 1463 */ 1464 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL); 1465 if (vma) 1466 goto out; 1467 1468 /* 1469 * Determine the object being mapped and call the appropriate 1470 * specific mapper. the address has already been validated, but 1471 * not unmapped, but the maps are removed from the list. 1472 */ 1473 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1474 if (!vma) { 1475 error = -ENOMEM; 1476 goto unacct_error; 1477 } 1478 1479 vma->vm_mm = mm; 1480 vma->vm_start = addr; 1481 vma->vm_end = addr + len; 1482 vma->vm_flags = vm_flags; 1483 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1484 vma->vm_pgoff = pgoff; 1485 INIT_LIST_HEAD(&vma->anon_vma_chain); 1486 1487 error = -EINVAL; /* when rejecting VM_GROWSDOWN|VM_GROWSUP */ 1488 1489 if (file) { 1490 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1491 goto free_vma; 1492 if (vm_flags & VM_DENYWRITE) { 1493 error = deny_write_access(file); 1494 if (error) 1495 goto free_vma; 1496 correct_wcount = 1; 1497 } 1498 vma->vm_file = get_file(file); 1499 error = file->f_op->mmap(file, vma); 1500 if (error) 1501 goto unmap_and_free_vma; 1502 1503 /* Can addr have changed?? 1504 * 1505 * Answer: Yes, several device drivers can do it in their 1506 * f_op->mmap method. -DaveM 1507 * Bug: If addr is changed, prev, rb_link, rb_parent should 1508 * be updated for vma_link() 1509 */ 1510 WARN_ON_ONCE(addr != vma->vm_start); 1511 1512 addr = vma->vm_start; 1513 pgoff = vma->vm_pgoff; 1514 vm_flags = vma->vm_flags; 1515 } else if (vm_flags & VM_SHARED) { 1516 if (unlikely(vm_flags & (VM_GROWSDOWN|VM_GROWSUP))) 1517 goto free_vma; 1518 error = shmem_zero_setup(vma); 1519 if (error) 1520 goto free_vma; 1521 } 1522 1523 if (vma_wants_writenotify(vma)) { 1524 pgprot_t pprot = vma->vm_page_prot; 1525 1526 /* Can vma->vm_page_prot have changed?? 1527 * 1528 * Answer: Yes, drivers may have changed it in their 1529 * f_op->mmap method. 1530 * 1531 * Ensures that vmas marked as uncached stay that way. 1532 */ 1533 vma->vm_page_prot = vm_get_page_prot(vm_flags & ~VM_SHARED); 1534 if (pgprot_val(pprot) == pgprot_val(pgprot_noncached(pprot))) 1535 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); 1536 } 1537 1538 vma_link(mm, vma, prev, rb_link, rb_parent); 1539 file = vma->vm_file; 1540 1541 /* Once vma denies write, undo our temporary denial count */ 1542 if (correct_wcount) 1543 atomic_inc(&inode->i_writecount); 1544 out: 1545 perf_event_mmap(vma); 1546 1547 vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT); 1548 if (vm_flags & VM_LOCKED) { 1549 if (!((vm_flags & VM_SPECIAL) || is_vm_hugetlb_page(vma) || 1550 vma == get_gate_vma(current->mm))) 1551 mm->locked_vm += (len >> PAGE_SHIFT); 1552 else 1553 vma->vm_flags &= ~VM_LOCKED; 1554 } 1555 1556 if (file) 1557 uprobe_mmap(vma); 1558 1559 return addr; 1560 1561 unmap_and_free_vma: 1562 if (correct_wcount) 1563 atomic_inc(&inode->i_writecount); 1564 vma->vm_file = NULL; 1565 fput(file); 1566 1567 /* Undo any partial mapping done by a device driver. */ 1568 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1569 charged = 0; 1570 free_vma: 1571 kmem_cache_free(vm_area_cachep, vma); 1572 unacct_error: 1573 if (charged) 1574 vm_unacct_memory(charged); 1575 return error; 1576 } 1577 1578 unsigned long unmapped_area(struct vm_unmapped_area_info *info) 1579 { 1580 /* 1581 * We implement the search by looking for an rbtree node that 1582 * immediately follows a suitable gap. That is, 1583 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; 1584 * - gap_end = vma->vm_start >= info->low_limit + length; 1585 * - gap_end - gap_start >= length 1586 */ 1587 1588 struct mm_struct *mm = current->mm; 1589 struct vm_area_struct *vma; 1590 unsigned long length, low_limit, high_limit, gap_start, gap_end; 1591 1592 /* Adjust search length to account for worst case alignment overhead */ 1593 length = info->length + info->align_mask; 1594 if (length < info->length) 1595 return -ENOMEM; 1596 1597 /* Adjust search limits by the desired length */ 1598 if (info->high_limit < length) 1599 return -ENOMEM; 1600 high_limit = info->high_limit - length; 1601 1602 if (info->low_limit > high_limit) 1603 return -ENOMEM; 1604 low_limit = info->low_limit + length; 1605 1606 /* Check if rbtree root looks promising */ 1607 if (RB_EMPTY_ROOT(&mm->mm_rb)) 1608 goto check_highest; 1609 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); 1610 if (vma->rb_subtree_gap < length) 1611 goto check_highest; 1612 1613 while (true) { 1614 /* Visit left subtree if it looks promising */ 1615 gap_end = vma->vm_start; 1616 if (gap_end >= low_limit && vma->vm_rb.rb_left) { 1617 struct vm_area_struct *left = 1618 rb_entry(vma->vm_rb.rb_left, 1619 struct vm_area_struct, vm_rb); 1620 if (left->rb_subtree_gap >= length) { 1621 vma = left; 1622 continue; 1623 } 1624 } 1625 1626 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; 1627 check_current: 1628 /* Check if current node has a suitable gap */ 1629 if (gap_start > high_limit) 1630 return -ENOMEM; 1631 if (gap_end >= low_limit && gap_end - gap_start >= length) 1632 goto found; 1633 1634 /* Visit right subtree if it looks promising */ 1635 if (vma->vm_rb.rb_right) { 1636 struct vm_area_struct *right = 1637 rb_entry(vma->vm_rb.rb_right, 1638 struct vm_area_struct, vm_rb); 1639 if (right->rb_subtree_gap >= length) { 1640 vma = right; 1641 continue; 1642 } 1643 } 1644 1645 /* Go back up the rbtree to find next candidate node */ 1646 while (true) { 1647 struct rb_node *prev = &vma->vm_rb; 1648 if (!rb_parent(prev)) 1649 goto check_highest; 1650 vma = rb_entry(rb_parent(prev), 1651 struct vm_area_struct, vm_rb); 1652 if (prev == vma->vm_rb.rb_left) { 1653 gap_start = vma->vm_prev->vm_end; 1654 gap_end = vma->vm_start; 1655 goto check_current; 1656 } 1657 } 1658 } 1659 1660 check_highest: 1661 /* Check highest gap, which does not precede any rbtree node */ 1662 gap_start = mm->highest_vm_end; 1663 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ 1664 if (gap_start > high_limit) 1665 return -ENOMEM; 1666 1667 found: 1668 /* We found a suitable gap. Clip it with the original low_limit. */ 1669 if (gap_start < info->low_limit) 1670 gap_start = info->low_limit; 1671 1672 /* Adjust gap address to the desired alignment */ 1673 gap_start += (info->align_offset - gap_start) & info->align_mask; 1674 1675 VM_BUG_ON(gap_start + info->length > info->high_limit); 1676 VM_BUG_ON(gap_start + info->length > gap_end); 1677 return gap_start; 1678 } 1679 1680 unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) 1681 { 1682 struct mm_struct *mm = current->mm; 1683 struct vm_area_struct *vma; 1684 unsigned long length, low_limit, high_limit, gap_start, gap_end; 1685 1686 /* Adjust search length to account for worst case alignment overhead */ 1687 length = info->length + info->align_mask; 1688 if (length < info->length) 1689 return -ENOMEM; 1690 1691 /* 1692 * Adjust search limits by the desired length. 1693 * See implementation comment at top of unmapped_area(). 1694 */ 1695 gap_end = info->high_limit; 1696 if (gap_end < length) 1697 return -ENOMEM; 1698 high_limit = gap_end - length; 1699 1700 if (info->low_limit > high_limit) 1701 return -ENOMEM; 1702 low_limit = info->low_limit + length; 1703 1704 /* Check highest gap, which does not precede any rbtree node */ 1705 gap_start = mm->highest_vm_end; 1706 if (gap_start <= high_limit) 1707 goto found_highest; 1708 1709 /* Check if rbtree root looks promising */ 1710 if (RB_EMPTY_ROOT(&mm->mm_rb)) 1711 return -ENOMEM; 1712 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); 1713 if (vma->rb_subtree_gap < length) 1714 return -ENOMEM; 1715 1716 while (true) { 1717 /* Visit right subtree if it looks promising */ 1718 gap_start = vma->vm_prev ? vma->vm_prev->vm_end : 0; 1719 if (gap_start <= high_limit && vma->vm_rb.rb_right) { 1720 struct vm_area_struct *right = 1721 rb_entry(vma->vm_rb.rb_right, 1722 struct vm_area_struct, vm_rb); 1723 if (right->rb_subtree_gap >= length) { 1724 vma = right; 1725 continue; 1726 } 1727 } 1728 1729 check_current: 1730 /* Check if current node has a suitable gap */ 1731 gap_end = vma->vm_start; 1732 if (gap_end < low_limit) 1733 return -ENOMEM; 1734 if (gap_start <= high_limit && gap_end - gap_start >= length) 1735 goto found; 1736 1737 /* Visit left subtree if it looks promising */ 1738 if (vma->vm_rb.rb_left) { 1739 struct vm_area_struct *left = 1740 rb_entry(vma->vm_rb.rb_left, 1741 struct vm_area_struct, vm_rb); 1742 if (left->rb_subtree_gap >= length) { 1743 vma = left; 1744 continue; 1745 } 1746 } 1747 1748 /* Go back up the rbtree to find next candidate node */ 1749 while (true) { 1750 struct rb_node *prev = &vma->vm_rb; 1751 if (!rb_parent(prev)) 1752 return -ENOMEM; 1753 vma = rb_entry(rb_parent(prev), 1754 struct vm_area_struct, vm_rb); 1755 if (prev == vma->vm_rb.rb_right) { 1756 gap_start = vma->vm_prev ? 1757 vma->vm_prev->vm_end : 0; 1758 goto check_current; 1759 } 1760 } 1761 } 1762 1763 found: 1764 /* We found a suitable gap. Clip it with the original high_limit. */ 1765 if (gap_end > info->high_limit) 1766 gap_end = info->high_limit; 1767 1768 found_highest: 1769 /* Compute highest gap address at the desired alignment */ 1770 gap_end -= info->length; 1771 gap_end -= (gap_end - info->align_offset) & info->align_mask; 1772 1773 VM_BUG_ON(gap_end < info->low_limit); 1774 VM_BUG_ON(gap_end < gap_start); 1775 return gap_end; 1776 } 1777 1778 /* Get an address range which is currently unmapped. 1779 * For shmat() with addr=0. 1780 * 1781 * Ugly calling convention alert: 1782 * Return value with the low bits set means error value, 1783 * ie 1784 * if (ret & ~PAGE_MASK) 1785 * error = ret; 1786 * 1787 * This function "knows" that -ENOMEM has the bits set. 1788 */ 1789 #ifndef HAVE_ARCH_UNMAPPED_AREA 1790 unsigned long 1791 arch_get_unmapped_area(struct file *filp, unsigned long addr, 1792 unsigned long len, unsigned long pgoff, unsigned long flags) 1793 { 1794 struct mm_struct *mm = current->mm; 1795 struct vm_area_struct *vma; 1796 struct vm_unmapped_area_info info; 1797 1798 if (len > TASK_SIZE) 1799 return -ENOMEM; 1800 1801 if (flags & MAP_FIXED) 1802 return addr; 1803 1804 if (addr) { 1805 addr = PAGE_ALIGN(addr); 1806 vma = find_vma(mm, addr); 1807 if (TASK_SIZE - len >= addr && 1808 (!vma || addr + len <= vma->vm_start)) 1809 return addr; 1810 } 1811 1812 info.flags = 0; 1813 info.length = len; 1814 info.low_limit = TASK_UNMAPPED_BASE; 1815 info.high_limit = TASK_SIZE; 1816 info.align_mask = 0; 1817 return vm_unmapped_area(&info); 1818 } 1819 #endif 1820 1821 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1822 { 1823 /* 1824 * Is this a new hole at the lowest possible address? 1825 */ 1826 if (addr >= TASK_UNMAPPED_BASE && addr < mm->free_area_cache) 1827 mm->free_area_cache = addr; 1828 } 1829 1830 /* 1831 * This mmap-allocator allocates new areas top-down from below the 1832 * stack's low limit (the base): 1833 */ 1834 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 1835 unsigned long 1836 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0, 1837 const unsigned long len, const unsigned long pgoff, 1838 const unsigned long flags) 1839 { 1840 struct vm_area_struct *vma; 1841 struct mm_struct *mm = current->mm; 1842 unsigned long addr = addr0; 1843 struct vm_unmapped_area_info info; 1844 1845 /* requested length too big for entire address space */ 1846 if (len > TASK_SIZE) 1847 return -ENOMEM; 1848 1849 if (flags & MAP_FIXED) 1850 return addr; 1851 1852 /* requesting a specific address */ 1853 if (addr) { 1854 addr = PAGE_ALIGN(addr); 1855 vma = find_vma(mm, addr); 1856 if (TASK_SIZE - len >= addr && 1857 (!vma || addr + len <= vma->vm_start)) 1858 return addr; 1859 } 1860 1861 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 1862 info.length = len; 1863 info.low_limit = PAGE_SIZE; 1864 info.high_limit = mm->mmap_base; 1865 info.align_mask = 0; 1866 addr = vm_unmapped_area(&info); 1867 1868 /* 1869 * A failed mmap() very likely causes application failure, 1870 * so fall back to the bottom-up function here. This scenario 1871 * can happen with large stack limits and large mmap() 1872 * allocations. 1873 */ 1874 if (addr & ~PAGE_MASK) { 1875 VM_BUG_ON(addr != -ENOMEM); 1876 info.flags = 0; 1877 info.low_limit = TASK_UNMAPPED_BASE; 1878 info.high_limit = TASK_SIZE; 1879 addr = vm_unmapped_area(&info); 1880 } 1881 1882 return addr; 1883 } 1884 #endif 1885 1886 void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr) 1887 { 1888 /* 1889 * Is this a new hole at the highest possible address? 1890 */ 1891 if (addr > mm->free_area_cache) 1892 mm->free_area_cache = addr; 1893 1894 /* dont allow allocations above current base */ 1895 if (mm->free_area_cache > mm->mmap_base) 1896 mm->free_area_cache = mm->mmap_base; 1897 } 1898 1899 unsigned long 1900 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 1901 unsigned long pgoff, unsigned long flags) 1902 { 1903 unsigned long (*get_area)(struct file *, unsigned long, 1904 unsigned long, unsigned long, unsigned long); 1905 1906 unsigned long error = arch_mmap_check(addr, len, flags); 1907 if (error) 1908 return error; 1909 1910 /* Careful about overflows.. */ 1911 if (len > TASK_SIZE) 1912 return -ENOMEM; 1913 1914 get_area = current->mm->get_unmapped_area; 1915 if (file && file->f_op && file->f_op->get_unmapped_area) 1916 get_area = file->f_op->get_unmapped_area; 1917 addr = get_area(file, addr, len, pgoff, flags); 1918 if (IS_ERR_VALUE(addr)) 1919 return addr; 1920 1921 if (addr > TASK_SIZE - len) 1922 return -ENOMEM; 1923 if (addr & ~PAGE_MASK) 1924 return -EINVAL; 1925 1926 addr = arch_rebalance_pgtables(addr, len); 1927 error = security_mmap_addr(addr); 1928 return error ? error : addr; 1929 } 1930 1931 EXPORT_SYMBOL(get_unmapped_area); 1932 1933 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 1934 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 1935 { 1936 struct vm_area_struct *vma = NULL; 1937 1938 if (WARN_ON_ONCE(!mm)) /* Remove this in linux-3.6 */ 1939 return NULL; 1940 1941 /* Check the cache first. */ 1942 /* (Cache hit rate is typically around 35%.) */ 1943 vma = mm->mmap_cache; 1944 if (!(vma && vma->vm_end > addr && vma->vm_start <= addr)) { 1945 struct rb_node *rb_node; 1946 1947 rb_node = mm->mm_rb.rb_node; 1948 vma = NULL; 1949 1950 while (rb_node) { 1951 struct vm_area_struct *vma_tmp; 1952 1953 vma_tmp = rb_entry(rb_node, 1954 struct vm_area_struct, vm_rb); 1955 1956 if (vma_tmp->vm_end > addr) { 1957 vma = vma_tmp; 1958 if (vma_tmp->vm_start <= addr) 1959 break; 1960 rb_node = rb_node->rb_left; 1961 } else 1962 rb_node = rb_node->rb_right; 1963 } 1964 if (vma) 1965 mm->mmap_cache = vma; 1966 } 1967 return vma; 1968 } 1969 1970 EXPORT_SYMBOL(find_vma); 1971 1972 /* 1973 * Same as find_vma, but also return a pointer to the previous VMA in *pprev. 1974 */ 1975 struct vm_area_struct * 1976 find_vma_prev(struct mm_struct *mm, unsigned long addr, 1977 struct vm_area_struct **pprev) 1978 { 1979 struct vm_area_struct *vma; 1980 1981 vma = find_vma(mm, addr); 1982 if (vma) { 1983 *pprev = vma->vm_prev; 1984 } else { 1985 struct rb_node *rb_node = mm->mm_rb.rb_node; 1986 *pprev = NULL; 1987 while (rb_node) { 1988 *pprev = rb_entry(rb_node, struct vm_area_struct, vm_rb); 1989 rb_node = rb_node->rb_right; 1990 } 1991 } 1992 return vma; 1993 } 1994 1995 /* 1996 * Verify that the stack growth is acceptable and 1997 * update accounting. This is shared with both the 1998 * grow-up and grow-down cases. 1999 */ 2000 static int acct_stack_growth(struct vm_area_struct *vma, unsigned long size, unsigned long grow) 2001 { 2002 struct mm_struct *mm = vma->vm_mm; 2003 struct rlimit *rlim = current->signal->rlim; 2004 unsigned long new_start; 2005 2006 /* address space limit tests */ 2007 if (!may_expand_vm(mm, grow)) 2008 return -ENOMEM; 2009 2010 /* Stack limit test */ 2011 if (size > ACCESS_ONCE(rlim[RLIMIT_STACK].rlim_cur)) 2012 return -ENOMEM; 2013 2014 /* mlock limit tests */ 2015 if (vma->vm_flags & VM_LOCKED) { 2016 unsigned long locked; 2017 unsigned long limit; 2018 locked = mm->locked_vm + grow; 2019 limit = ACCESS_ONCE(rlim[RLIMIT_MEMLOCK].rlim_cur); 2020 limit >>= PAGE_SHIFT; 2021 if (locked > limit && !capable(CAP_IPC_LOCK)) 2022 return -ENOMEM; 2023 } 2024 2025 /* Check to ensure the stack will not grow into a hugetlb-only region */ 2026 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 2027 vma->vm_end - size; 2028 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 2029 return -EFAULT; 2030 2031 /* 2032 * Overcommit.. This must be the final test, as it will 2033 * update security statistics. 2034 */ 2035 if (security_vm_enough_memory_mm(mm, grow)) 2036 return -ENOMEM; 2037 2038 /* Ok, everything looks good - let it rip */ 2039 if (vma->vm_flags & VM_LOCKED) 2040 mm->locked_vm += grow; 2041 vm_stat_account(mm, vma->vm_flags, vma->vm_file, grow); 2042 return 0; 2043 } 2044 2045 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 2046 /* 2047 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 2048 * vma is the last one with address > vma->vm_end. Have to extend vma. 2049 */ 2050 int expand_upwards(struct vm_area_struct *vma, unsigned long address) 2051 { 2052 int error; 2053 2054 if (!(vma->vm_flags & VM_GROWSUP)) 2055 return -EFAULT; 2056 2057 /* 2058 * We must make sure the anon_vma is allocated 2059 * so that the anon_vma locking is not a noop. 2060 */ 2061 if (unlikely(anon_vma_prepare(vma))) 2062 return -ENOMEM; 2063 vma_lock_anon_vma(vma); 2064 2065 /* 2066 * vma->vm_start/vm_end cannot change under us because the caller 2067 * is required to hold the mmap_sem in read mode. We need the 2068 * anon_vma lock to serialize against concurrent expand_stacks. 2069 * Also guard against wrapping around to address 0. 2070 */ 2071 if (address < PAGE_ALIGN(address+4)) 2072 address = PAGE_ALIGN(address+4); 2073 else { 2074 vma_unlock_anon_vma(vma); 2075 return -ENOMEM; 2076 } 2077 error = 0; 2078 2079 /* Somebody else might have raced and expanded it already */ 2080 if (address > vma->vm_end) { 2081 unsigned long size, grow; 2082 2083 size = address - vma->vm_start; 2084 grow = (address - vma->vm_end) >> PAGE_SHIFT; 2085 2086 error = -ENOMEM; 2087 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { 2088 error = acct_stack_growth(vma, size, grow); 2089 if (!error) { 2090 /* 2091 * vma_gap_update() doesn't support concurrent 2092 * updates, but we only hold a shared mmap_sem 2093 * lock here, so we need to protect against 2094 * concurrent vma expansions. 2095 * vma_lock_anon_vma() doesn't help here, as 2096 * we don't guarantee that all growable vmas 2097 * in a mm share the same root anon vma. 2098 * So, we reuse mm->page_table_lock to guard 2099 * against concurrent vma expansions. 2100 */ 2101 spin_lock(&vma->vm_mm->page_table_lock); 2102 anon_vma_interval_tree_pre_update_vma(vma); 2103 vma->vm_end = address; 2104 anon_vma_interval_tree_post_update_vma(vma); 2105 if (vma->vm_next) 2106 vma_gap_update(vma->vm_next); 2107 else 2108 vma->vm_mm->highest_vm_end = address; 2109 spin_unlock(&vma->vm_mm->page_table_lock); 2110 2111 perf_event_mmap(vma); 2112 } 2113 } 2114 } 2115 vma_unlock_anon_vma(vma); 2116 khugepaged_enter_vma_merge(vma); 2117 validate_mm(vma->vm_mm); 2118 return error; 2119 } 2120 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 2121 2122 /* 2123 * vma is the first one with address < vma->vm_start. Have to extend vma. 2124 */ 2125 int expand_downwards(struct vm_area_struct *vma, 2126 unsigned long address) 2127 { 2128 int error; 2129 2130 /* 2131 * We must make sure the anon_vma is allocated 2132 * so that the anon_vma locking is not a noop. 2133 */ 2134 if (unlikely(anon_vma_prepare(vma))) 2135 return -ENOMEM; 2136 2137 address &= PAGE_MASK; 2138 error = security_mmap_addr(address); 2139 if (error) 2140 return error; 2141 2142 vma_lock_anon_vma(vma); 2143 2144 /* 2145 * vma->vm_start/vm_end cannot change under us because the caller 2146 * is required to hold the mmap_sem in read mode. We need the 2147 * anon_vma lock to serialize against concurrent expand_stacks. 2148 */ 2149 2150 /* Somebody else might have raced and expanded it already */ 2151 if (address < vma->vm_start) { 2152 unsigned long size, grow; 2153 2154 size = vma->vm_end - address; 2155 grow = (vma->vm_start - address) >> PAGE_SHIFT; 2156 2157 error = -ENOMEM; 2158 if (grow <= vma->vm_pgoff) { 2159 error = acct_stack_growth(vma, size, grow); 2160 if (!error) { 2161 /* 2162 * vma_gap_update() doesn't support concurrent 2163 * updates, but we only hold a shared mmap_sem 2164 * lock here, so we need to protect against 2165 * concurrent vma expansions. 2166 * vma_lock_anon_vma() doesn't help here, as 2167 * we don't guarantee that all growable vmas 2168 * in a mm share the same root anon vma. 2169 * So, we reuse mm->page_table_lock to guard 2170 * against concurrent vma expansions. 2171 */ 2172 spin_lock(&vma->vm_mm->page_table_lock); 2173 anon_vma_interval_tree_pre_update_vma(vma); 2174 vma->vm_start = address; 2175 vma->vm_pgoff -= grow; 2176 anon_vma_interval_tree_post_update_vma(vma); 2177 vma_gap_update(vma); 2178 spin_unlock(&vma->vm_mm->page_table_lock); 2179 2180 perf_event_mmap(vma); 2181 } 2182 } 2183 } 2184 vma_unlock_anon_vma(vma); 2185 khugepaged_enter_vma_merge(vma); 2186 validate_mm(vma->vm_mm); 2187 return error; 2188 } 2189 2190 /* 2191 * Note how expand_stack() refuses to expand the stack all the way to 2192 * abut the next virtual mapping, *unless* that mapping itself is also 2193 * a stack mapping. We want to leave room for a guard page, after all 2194 * (the guard page itself is not added here, that is done by the 2195 * actual page faulting logic) 2196 * 2197 * This matches the behavior of the guard page logic (see mm/memory.c: 2198 * check_stack_guard_page()), which only allows the guard page to be 2199 * removed under these circumstances. 2200 */ 2201 #ifdef CONFIG_STACK_GROWSUP 2202 int expand_stack(struct vm_area_struct *vma, unsigned long address) 2203 { 2204 struct vm_area_struct *next; 2205 2206 address &= PAGE_MASK; 2207 next = vma->vm_next; 2208 if (next && next->vm_start == address + PAGE_SIZE) { 2209 if (!(next->vm_flags & VM_GROWSUP)) 2210 return -ENOMEM; 2211 } 2212 return expand_upwards(vma, address); 2213 } 2214 2215 struct vm_area_struct * 2216 find_extend_vma(struct mm_struct *mm, unsigned long addr) 2217 { 2218 struct vm_area_struct *vma, *prev; 2219 2220 addr &= PAGE_MASK; 2221 vma = find_vma_prev(mm, addr, &prev); 2222 if (vma && (vma->vm_start <= addr)) 2223 return vma; 2224 if (!prev || expand_stack(prev, addr)) 2225 return NULL; 2226 if (prev->vm_flags & VM_LOCKED) 2227 __mlock_vma_pages_range(prev, addr, prev->vm_end, NULL); 2228 return prev; 2229 } 2230 #else 2231 int expand_stack(struct vm_area_struct *vma, unsigned long address) 2232 { 2233 struct vm_area_struct *prev; 2234 2235 address &= PAGE_MASK; 2236 prev = vma->vm_prev; 2237 if (prev && prev->vm_end == address) { 2238 if (!(prev->vm_flags & VM_GROWSDOWN)) 2239 return -ENOMEM; 2240 } 2241 return expand_downwards(vma, address); 2242 } 2243 2244 struct vm_area_struct * 2245 find_extend_vma(struct mm_struct * mm, unsigned long addr) 2246 { 2247 struct vm_area_struct * vma; 2248 unsigned long start; 2249 2250 addr &= PAGE_MASK; 2251 vma = find_vma(mm,addr); 2252 if (!vma) 2253 return NULL; 2254 if (vma->vm_start <= addr) 2255 return vma; 2256 if (!(vma->vm_flags & VM_GROWSDOWN)) 2257 return NULL; 2258 start = vma->vm_start; 2259 if (expand_stack(vma, addr)) 2260 return NULL; 2261 if (vma->vm_flags & VM_LOCKED) 2262 __mlock_vma_pages_range(vma, addr, start, NULL); 2263 return vma; 2264 } 2265 #endif 2266 2267 /* 2268 * Ok - we have the memory areas we should free on the vma list, 2269 * so release them, and do the vma updates. 2270 * 2271 * Called with the mm semaphore held. 2272 */ 2273 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 2274 { 2275 unsigned long nr_accounted = 0; 2276 2277 /* Update high watermark before we lower total_vm */ 2278 update_hiwater_vm(mm); 2279 do { 2280 long nrpages = vma_pages(vma); 2281 2282 if (vma->vm_flags & VM_ACCOUNT) 2283 nr_accounted += nrpages; 2284 vm_stat_account(mm, vma->vm_flags, vma->vm_file, -nrpages); 2285 vma = remove_vma(vma); 2286 } while (vma); 2287 vm_unacct_memory(nr_accounted); 2288 validate_mm(mm); 2289 } 2290 2291 /* 2292 * Get rid of page table information in the indicated region. 2293 * 2294 * Called with the mm semaphore held. 2295 */ 2296 static void unmap_region(struct mm_struct *mm, 2297 struct vm_area_struct *vma, struct vm_area_struct *prev, 2298 unsigned long start, unsigned long end) 2299 { 2300 struct vm_area_struct *next = prev? prev->vm_next: mm->mmap; 2301 struct mmu_gather tlb; 2302 2303 lru_add_drain(); 2304 tlb_gather_mmu(&tlb, mm, 0); 2305 update_hiwater_rss(mm); 2306 unmap_vmas(&tlb, vma, start, end); 2307 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, 2308 next ? next->vm_start : 0); 2309 tlb_finish_mmu(&tlb, start, end); 2310 } 2311 2312 /* 2313 * Create a list of vma's touched by the unmap, removing them from the mm's 2314 * vma list as we go.. 2315 */ 2316 static void 2317 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 2318 struct vm_area_struct *prev, unsigned long end) 2319 { 2320 struct vm_area_struct **insertion_point; 2321 struct vm_area_struct *tail_vma = NULL; 2322 unsigned long addr; 2323 2324 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 2325 vma->vm_prev = NULL; 2326 do { 2327 vma_rb_erase(vma, &mm->mm_rb); 2328 mm->map_count--; 2329 tail_vma = vma; 2330 vma = vma->vm_next; 2331 } while (vma && vma->vm_start < end); 2332 *insertion_point = vma; 2333 if (vma) { 2334 vma->vm_prev = prev; 2335 vma_gap_update(vma); 2336 } else 2337 mm->highest_vm_end = prev ? prev->vm_end : 0; 2338 tail_vma->vm_next = NULL; 2339 if (mm->unmap_area == arch_unmap_area) 2340 addr = prev ? prev->vm_end : mm->mmap_base; 2341 else 2342 addr = vma ? vma->vm_start : mm->mmap_base; 2343 mm->unmap_area(mm, addr); 2344 mm->mmap_cache = NULL; /* Kill the cache. */ 2345 } 2346 2347 /* 2348 * __split_vma() bypasses sysctl_max_map_count checking. We use this on the 2349 * munmap path where it doesn't make sense to fail. 2350 */ 2351 static int __split_vma(struct mm_struct * mm, struct vm_area_struct * vma, 2352 unsigned long addr, int new_below) 2353 { 2354 struct mempolicy *pol; 2355 struct vm_area_struct *new; 2356 int err = -ENOMEM; 2357 2358 if (is_vm_hugetlb_page(vma) && (addr & 2359 ~(huge_page_mask(hstate_vma(vma))))) 2360 return -EINVAL; 2361 2362 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2363 if (!new) 2364 goto out_err; 2365 2366 /* most fields are the same, copy all, and then fixup */ 2367 *new = *vma; 2368 2369 INIT_LIST_HEAD(&new->anon_vma_chain); 2370 2371 if (new_below) 2372 new->vm_end = addr; 2373 else { 2374 new->vm_start = addr; 2375 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 2376 } 2377 2378 pol = mpol_dup(vma_policy(vma)); 2379 if (IS_ERR(pol)) { 2380 err = PTR_ERR(pol); 2381 goto out_free_vma; 2382 } 2383 vma_set_policy(new, pol); 2384 2385 if (anon_vma_clone(new, vma)) 2386 goto out_free_mpol; 2387 2388 if (new->vm_file) 2389 get_file(new->vm_file); 2390 2391 if (new->vm_ops && new->vm_ops->open) 2392 new->vm_ops->open(new); 2393 2394 if (new_below) 2395 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 2396 ((addr - new->vm_start) >> PAGE_SHIFT), new); 2397 else 2398 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 2399 2400 /* Success. */ 2401 if (!err) 2402 return 0; 2403 2404 /* Clean everything up if vma_adjust failed. */ 2405 if (new->vm_ops && new->vm_ops->close) 2406 new->vm_ops->close(new); 2407 if (new->vm_file) 2408 fput(new->vm_file); 2409 unlink_anon_vmas(new); 2410 out_free_mpol: 2411 mpol_put(pol); 2412 out_free_vma: 2413 kmem_cache_free(vm_area_cachep, new); 2414 out_err: 2415 return err; 2416 } 2417 2418 /* 2419 * Split a vma into two pieces at address 'addr', a new vma is allocated 2420 * either for the first part or the tail. 2421 */ 2422 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 2423 unsigned long addr, int new_below) 2424 { 2425 if (mm->map_count >= sysctl_max_map_count) 2426 return -ENOMEM; 2427 2428 return __split_vma(mm, vma, addr, new_below); 2429 } 2430 2431 /* Munmap is split into 2 main parts -- this part which finds 2432 * what needs doing, and the areas themselves, which do the 2433 * work. This now handles partial unmappings. 2434 * Jeremy Fitzhardinge <jeremy@goop.org> 2435 */ 2436 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 2437 { 2438 unsigned long end; 2439 struct vm_area_struct *vma, *prev, *last; 2440 2441 if ((start & ~PAGE_MASK) || start > TASK_SIZE || len > TASK_SIZE-start) 2442 return -EINVAL; 2443 2444 if ((len = PAGE_ALIGN(len)) == 0) 2445 return -EINVAL; 2446 2447 /* Find the first overlapping VMA */ 2448 vma = find_vma(mm, start); 2449 if (!vma) 2450 return 0; 2451 prev = vma->vm_prev; 2452 /* we have start < vma->vm_end */ 2453 2454 /* if it doesn't overlap, we have nothing.. */ 2455 end = start + len; 2456 if (vma->vm_start >= end) 2457 return 0; 2458 2459 /* 2460 * If we need to split any vma, do it now to save pain later. 2461 * 2462 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 2463 * unmapped vm_area_struct will remain in use: so lower split_vma 2464 * places tmp vma above, and higher split_vma places tmp vma below. 2465 */ 2466 if (start > vma->vm_start) { 2467 int error; 2468 2469 /* 2470 * Make sure that map_count on return from munmap() will 2471 * not exceed its limit; but let map_count go just above 2472 * its limit temporarily, to help free resources as expected. 2473 */ 2474 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) 2475 return -ENOMEM; 2476 2477 error = __split_vma(mm, vma, start, 0); 2478 if (error) 2479 return error; 2480 prev = vma; 2481 } 2482 2483 /* Does it split the last one? */ 2484 last = find_vma(mm, end); 2485 if (last && end > last->vm_start) { 2486 int error = __split_vma(mm, last, end, 1); 2487 if (error) 2488 return error; 2489 } 2490 vma = prev? prev->vm_next: mm->mmap; 2491 2492 /* 2493 * unlock any mlock()ed ranges before detaching vmas 2494 */ 2495 if (mm->locked_vm) { 2496 struct vm_area_struct *tmp = vma; 2497 while (tmp && tmp->vm_start < end) { 2498 if (tmp->vm_flags & VM_LOCKED) { 2499 mm->locked_vm -= vma_pages(tmp); 2500 munlock_vma_pages_all(tmp); 2501 } 2502 tmp = tmp->vm_next; 2503 } 2504 } 2505 2506 /* 2507 * Remove the vma's, and unmap the actual pages 2508 */ 2509 detach_vmas_to_be_unmapped(mm, vma, prev, end); 2510 unmap_region(mm, vma, prev, start, end); 2511 2512 /* Fix up all other VM information */ 2513 remove_vma_list(mm, vma); 2514 2515 return 0; 2516 } 2517 2518 int vm_munmap(unsigned long start, size_t len) 2519 { 2520 int ret; 2521 struct mm_struct *mm = current->mm; 2522 2523 down_write(&mm->mmap_sem); 2524 ret = do_munmap(mm, start, len); 2525 up_write(&mm->mmap_sem); 2526 return ret; 2527 } 2528 EXPORT_SYMBOL(vm_munmap); 2529 2530 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 2531 { 2532 profile_munmap(addr); 2533 return vm_munmap(addr, len); 2534 } 2535 2536 static inline void verify_mm_writelocked(struct mm_struct *mm) 2537 { 2538 #ifdef CONFIG_DEBUG_VM 2539 if (unlikely(down_read_trylock(&mm->mmap_sem))) { 2540 WARN_ON(1); 2541 up_read(&mm->mmap_sem); 2542 } 2543 #endif 2544 } 2545 2546 /* 2547 * this is really a simplified "do_mmap". it only handles 2548 * anonymous maps. eventually we may be able to do some 2549 * brk-specific accounting here. 2550 */ 2551 static unsigned long do_brk(unsigned long addr, unsigned long len) 2552 { 2553 struct mm_struct * mm = current->mm; 2554 struct vm_area_struct * vma, * prev; 2555 unsigned long flags; 2556 struct rb_node ** rb_link, * rb_parent; 2557 pgoff_t pgoff = addr >> PAGE_SHIFT; 2558 int error; 2559 2560 len = PAGE_ALIGN(len); 2561 if (!len) 2562 return addr; 2563 2564 flags = VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 2565 2566 error = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); 2567 if (error & ~PAGE_MASK) 2568 return error; 2569 2570 /* 2571 * mlock MCL_FUTURE? 2572 */ 2573 if (mm->def_flags & VM_LOCKED) { 2574 unsigned long locked, lock_limit; 2575 locked = len >> PAGE_SHIFT; 2576 locked += mm->locked_vm; 2577 lock_limit = rlimit(RLIMIT_MEMLOCK); 2578 lock_limit >>= PAGE_SHIFT; 2579 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 2580 return -EAGAIN; 2581 } 2582 2583 /* 2584 * mm->mmap_sem is required to protect against another thread 2585 * changing the mappings in case we sleep. 2586 */ 2587 verify_mm_writelocked(mm); 2588 2589 /* 2590 * Clear old maps. this also does some error checking for us 2591 */ 2592 munmap_back: 2593 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) { 2594 if (do_munmap(mm, addr, len)) 2595 return -ENOMEM; 2596 goto munmap_back; 2597 } 2598 2599 /* Check against address space limits *after* clearing old maps... */ 2600 if (!may_expand_vm(mm, len >> PAGE_SHIFT)) 2601 return -ENOMEM; 2602 2603 if (mm->map_count > sysctl_max_map_count) 2604 return -ENOMEM; 2605 2606 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) 2607 return -ENOMEM; 2608 2609 /* Can we just expand an old private anonymous mapping? */ 2610 vma = vma_merge(mm, prev, addr, addr + len, flags, 2611 NULL, NULL, pgoff, NULL); 2612 if (vma) 2613 goto out; 2614 2615 /* 2616 * create a vma struct for an anonymous mapping 2617 */ 2618 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2619 if (!vma) { 2620 vm_unacct_memory(len >> PAGE_SHIFT); 2621 return -ENOMEM; 2622 } 2623 2624 INIT_LIST_HEAD(&vma->anon_vma_chain); 2625 vma->vm_mm = mm; 2626 vma->vm_start = addr; 2627 vma->vm_end = addr + len; 2628 vma->vm_pgoff = pgoff; 2629 vma->vm_flags = flags; 2630 vma->vm_page_prot = vm_get_page_prot(flags); 2631 vma_link(mm, vma, prev, rb_link, rb_parent); 2632 out: 2633 perf_event_mmap(vma); 2634 mm->total_vm += len >> PAGE_SHIFT; 2635 if (flags & VM_LOCKED) 2636 mm->locked_vm += (len >> PAGE_SHIFT); 2637 return addr; 2638 } 2639 2640 unsigned long vm_brk(unsigned long addr, unsigned long len) 2641 { 2642 struct mm_struct *mm = current->mm; 2643 unsigned long ret; 2644 bool populate; 2645 2646 down_write(&mm->mmap_sem); 2647 ret = do_brk(addr, len); 2648 populate = ((mm->def_flags & VM_LOCKED) != 0); 2649 up_write(&mm->mmap_sem); 2650 if (populate) 2651 mm_populate(addr, len); 2652 return ret; 2653 } 2654 EXPORT_SYMBOL(vm_brk); 2655 2656 /* Release all mmaps. */ 2657 void exit_mmap(struct mm_struct *mm) 2658 { 2659 struct mmu_gather tlb; 2660 struct vm_area_struct *vma; 2661 unsigned long nr_accounted = 0; 2662 2663 /* mm's last user has gone, and its about to be pulled down */ 2664 mmu_notifier_release(mm); 2665 2666 if (mm->locked_vm) { 2667 vma = mm->mmap; 2668 while (vma) { 2669 if (vma->vm_flags & VM_LOCKED) 2670 munlock_vma_pages_all(vma); 2671 vma = vma->vm_next; 2672 } 2673 } 2674 2675 arch_exit_mmap(mm); 2676 2677 vma = mm->mmap; 2678 if (!vma) /* Can happen if dup_mmap() received an OOM */ 2679 return; 2680 2681 lru_add_drain(); 2682 flush_cache_mm(mm); 2683 tlb_gather_mmu(&tlb, mm, 1); 2684 /* update_hiwater_rss(mm) here? but nobody should be looking */ 2685 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 2686 unmap_vmas(&tlb, vma, 0, -1); 2687 2688 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0); 2689 tlb_finish_mmu(&tlb, 0, -1); 2690 2691 /* 2692 * Walk the list again, actually closing and freeing it, 2693 * with preemption enabled, without holding any MM locks. 2694 */ 2695 while (vma) { 2696 if (vma->vm_flags & VM_ACCOUNT) 2697 nr_accounted += vma_pages(vma); 2698 vma = remove_vma(vma); 2699 } 2700 vm_unacct_memory(nr_accounted); 2701 2702 WARN_ON(mm->nr_ptes > (FIRST_USER_ADDRESS+PMD_SIZE-1)>>PMD_SHIFT); 2703 } 2704 2705 /* Insert vm structure into process list sorted by address 2706 * and into the inode's i_mmap tree. If vm_file is non-NULL 2707 * then i_mmap_mutex is taken here. 2708 */ 2709 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 2710 { 2711 struct vm_area_struct *prev; 2712 struct rb_node **rb_link, *rb_parent; 2713 2714 /* 2715 * The vm_pgoff of a purely anonymous vma should be irrelevant 2716 * until its first write fault, when page's anon_vma and index 2717 * are set. But now set the vm_pgoff it will almost certainly 2718 * end up with (unless mremap moves it elsewhere before that 2719 * first wfault), so /proc/pid/maps tells a consistent story. 2720 * 2721 * By setting it to reflect the virtual start address of the 2722 * vma, merges and splits can happen in a seamless way, just 2723 * using the existing file pgoff checks and manipulations. 2724 * Similarly in do_mmap_pgoff and in do_brk. 2725 */ 2726 if (!vma->vm_file) { 2727 BUG_ON(vma->anon_vma); 2728 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 2729 } 2730 if (find_vma_links(mm, vma->vm_start, vma->vm_end, 2731 &prev, &rb_link, &rb_parent)) 2732 return -ENOMEM; 2733 if ((vma->vm_flags & VM_ACCOUNT) && 2734 security_vm_enough_memory_mm(mm, vma_pages(vma))) 2735 return -ENOMEM; 2736 2737 vma_link(mm, vma, prev, rb_link, rb_parent); 2738 return 0; 2739 } 2740 2741 /* 2742 * Copy the vma structure to a new location in the same mm, 2743 * prior to moving page table entries, to effect an mremap move. 2744 */ 2745 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 2746 unsigned long addr, unsigned long len, pgoff_t pgoff, 2747 bool *need_rmap_locks) 2748 { 2749 struct vm_area_struct *vma = *vmap; 2750 unsigned long vma_start = vma->vm_start; 2751 struct mm_struct *mm = vma->vm_mm; 2752 struct vm_area_struct *new_vma, *prev; 2753 struct rb_node **rb_link, *rb_parent; 2754 struct mempolicy *pol; 2755 bool faulted_in_anon_vma = true; 2756 2757 /* 2758 * If anonymous vma has not yet been faulted, update new pgoff 2759 * to match new location, to increase its chance of merging. 2760 */ 2761 if (unlikely(!vma->vm_file && !vma->anon_vma)) { 2762 pgoff = addr >> PAGE_SHIFT; 2763 faulted_in_anon_vma = false; 2764 } 2765 2766 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) 2767 return NULL; /* should never get here */ 2768 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 2769 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma)); 2770 if (new_vma) { 2771 /* 2772 * Source vma may have been merged into new_vma 2773 */ 2774 if (unlikely(vma_start >= new_vma->vm_start && 2775 vma_start < new_vma->vm_end)) { 2776 /* 2777 * The only way we can get a vma_merge with 2778 * self during an mremap is if the vma hasn't 2779 * been faulted in yet and we were allowed to 2780 * reset the dst vma->vm_pgoff to the 2781 * destination address of the mremap to allow 2782 * the merge to happen. mremap must change the 2783 * vm_pgoff linearity between src and dst vmas 2784 * (in turn preventing a vma_merge) to be 2785 * safe. It is only safe to keep the vm_pgoff 2786 * linear if there are no pages mapped yet. 2787 */ 2788 VM_BUG_ON(faulted_in_anon_vma); 2789 *vmap = vma = new_vma; 2790 } 2791 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); 2792 } else { 2793 new_vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 2794 if (new_vma) { 2795 *new_vma = *vma; 2796 new_vma->vm_start = addr; 2797 new_vma->vm_end = addr + len; 2798 new_vma->vm_pgoff = pgoff; 2799 pol = mpol_dup(vma_policy(vma)); 2800 if (IS_ERR(pol)) 2801 goto out_free_vma; 2802 vma_set_policy(new_vma, pol); 2803 INIT_LIST_HEAD(&new_vma->anon_vma_chain); 2804 if (anon_vma_clone(new_vma, vma)) 2805 goto out_free_mempol; 2806 if (new_vma->vm_file) 2807 get_file(new_vma->vm_file); 2808 if (new_vma->vm_ops && new_vma->vm_ops->open) 2809 new_vma->vm_ops->open(new_vma); 2810 vma_link(mm, new_vma, prev, rb_link, rb_parent); 2811 *need_rmap_locks = false; 2812 } 2813 } 2814 return new_vma; 2815 2816 out_free_mempol: 2817 mpol_put(pol); 2818 out_free_vma: 2819 kmem_cache_free(vm_area_cachep, new_vma); 2820 return NULL; 2821 } 2822 2823 /* 2824 * Return true if the calling process may expand its vm space by the passed 2825 * number of pages 2826 */ 2827 int may_expand_vm(struct mm_struct *mm, unsigned long npages) 2828 { 2829 unsigned long cur = mm->total_vm; /* pages */ 2830 unsigned long lim; 2831 2832 lim = rlimit(RLIMIT_AS) >> PAGE_SHIFT; 2833 2834 if (cur + npages > lim) 2835 return 0; 2836 return 1; 2837 } 2838 2839 2840 static int special_mapping_fault(struct vm_area_struct *vma, 2841 struct vm_fault *vmf) 2842 { 2843 pgoff_t pgoff; 2844 struct page **pages; 2845 2846 /* 2847 * special mappings have no vm_file, and in that case, the mm 2848 * uses vm_pgoff internally. So we have to subtract it from here. 2849 * We are allowed to do this because we are the mm; do not copy 2850 * this code into drivers! 2851 */ 2852 pgoff = vmf->pgoff - vma->vm_pgoff; 2853 2854 for (pages = vma->vm_private_data; pgoff && *pages; ++pages) 2855 pgoff--; 2856 2857 if (*pages) { 2858 struct page *page = *pages; 2859 get_page(page); 2860 vmf->page = page; 2861 return 0; 2862 } 2863 2864 return VM_FAULT_SIGBUS; 2865 } 2866 2867 /* 2868 * Having a close hook prevents vma merging regardless of flags. 2869 */ 2870 static void special_mapping_close(struct vm_area_struct *vma) 2871 { 2872 } 2873 2874 static const struct vm_operations_struct special_mapping_vmops = { 2875 .close = special_mapping_close, 2876 .fault = special_mapping_fault, 2877 }; 2878 2879 /* 2880 * Called with mm->mmap_sem held for writing. 2881 * Insert a new vma covering the given region, with the given flags. 2882 * Its pages are supplied by the given array of struct page *. 2883 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 2884 * The region past the last page supplied will always produce SIGBUS. 2885 * The array pointer and the pages it points to are assumed to stay alive 2886 * for as long as this mapping might exist. 2887 */ 2888 int install_special_mapping(struct mm_struct *mm, 2889 unsigned long addr, unsigned long len, 2890 unsigned long vm_flags, struct page **pages) 2891 { 2892 int ret; 2893 struct vm_area_struct *vma; 2894 2895 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 2896 if (unlikely(vma == NULL)) 2897 return -ENOMEM; 2898 2899 INIT_LIST_HEAD(&vma->anon_vma_chain); 2900 vma->vm_mm = mm; 2901 vma->vm_start = addr; 2902 vma->vm_end = addr + len; 2903 2904 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND; 2905 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 2906 2907 vma->vm_ops = &special_mapping_vmops; 2908 vma->vm_private_data = pages; 2909 2910 ret = insert_vm_struct(mm, vma); 2911 if (ret) 2912 goto out; 2913 2914 mm->total_vm += len >> PAGE_SHIFT; 2915 2916 perf_event_mmap(vma); 2917 2918 return 0; 2919 2920 out: 2921 kmem_cache_free(vm_area_cachep, vma); 2922 return ret; 2923 } 2924 2925 static DEFINE_MUTEX(mm_all_locks_mutex); 2926 2927 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) 2928 { 2929 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { 2930 /* 2931 * The LSB of head.next can't change from under us 2932 * because we hold the mm_all_locks_mutex. 2933 */ 2934 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); 2935 /* 2936 * We can safely modify head.next after taking the 2937 * anon_vma->root->rwsem. If some other vma in this mm shares 2938 * the same anon_vma we won't take it again. 2939 * 2940 * No need of atomic instructions here, head.next 2941 * can't change from under us thanks to the 2942 * anon_vma->root->rwsem. 2943 */ 2944 if (__test_and_set_bit(0, (unsigned long *) 2945 &anon_vma->root->rb_root.rb_node)) 2946 BUG(); 2947 } 2948 } 2949 2950 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) 2951 { 2952 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 2953 /* 2954 * AS_MM_ALL_LOCKS can't change from under us because 2955 * we hold the mm_all_locks_mutex. 2956 * 2957 * Operations on ->flags have to be atomic because 2958 * even if AS_MM_ALL_LOCKS is stable thanks to the 2959 * mm_all_locks_mutex, there may be other cpus 2960 * changing other bitflags in parallel to us. 2961 */ 2962 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) 2963 BUG(); 2964 mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem); 2965 } 2966 } 2967 2968 /* 2969 * This operation locks against the VM for all pte/vma/mm related 2970 * operations that could ever happen on a certain mm. This includes 2971 * vmtruncate, try_to_unmap, and all page faults. 2972 * 2973 * The caller must take the mmap_sem in write mode before calling 2974 * mm_take_all_locks(). The caller isn't allowed to release the 2975 * mmap_sem until mm_drop_all_locks() returns. 2976 * 2977 * mmap_sem in write mode is required in order to block all operations 2978 * that could modify pagetables and free pages without need of 2979 * altering the vma layout (for example populate_range() with 2980 * nonlinear vmas). It's also needed in write mode to avoid new 2981 * anon_vmas to be associated with existing vmas. 2982 * 2983 * A single task can't take more than one mm_take_all_locks() in a row 2984 * or it would deadlock. 2985 * 2986 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in 2987 * mapping->flags avoid to take the same lock twice, if more than one 2988 * vma in this mm is backed by the same anon_vma or address_space. 2989 * 2990 * We can take all the locks in random order because the VM code 2991 * taking i_mmap_mutex or anon_vma->rwsem outside the mmap_sem never 2992 * takes more than one of them in a row. Secondly we're protected 2993 * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex. 2994 * 2995 * mm_take_all_locks() and mm_drop_all_locks are expensive operations 2996 * that may have to take thousand of locks. 2997 * 2998 * mm_take_all_locks() can fail if it's interrupted by signals. 2999 */ 3000 int mm_take_all_locks(struct mm_struct *mm) 3001 { 3002 struct vm_area_struct *vma; 3003 struct anon_vma_chain *avc; 3004 3005 BUG_ON(down_read_trylock(&mm->mmap_sem)); 3006 3007 mutex_lock(&mm_all_locks_mutex); 3008 3009 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3010 if (signal_pending(current)) 3011 goto out_unlock; 3012 if (vma->vm_file && vma->vm_file->f_mapping) 3013 vm_lock_mapping(mm, vma->vm_file->f_mapping); 3014 } 3015 3016 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3017 if (signal_pending(current)) 3018 goto out_unlock; 3019 if (vma->anon_vma) 3020 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 3021 vm_lock_anon_vma(mm, avc->anon_vma); 3022 } 3023 3024 return 0; 3025 3026 out_unlock: 3027 mm_drop_all_locks(mm); 3028 return -EINTR; 3029 } 3030 3031 static void vm_unlock_anon_vma(struct anon_vma *anon_vma) 3032 { 3033 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_node)) { 3034 /* 3035 * The LSB of head.next can't change to 0 from under 3036 * us because we hold the mm_all_locks_mutex. 3037 * 3038 * We must however clear the bitflag before unlocking 3039 * the vma so the users using the anon_vma->rb_root will 3040 * never see our bitflag. 3041 * 3042 * No need of atomic instructions here, head.next 3043 * can't change from under us until we release the 3044 * anon_vma->root->rwsem. 3045 */ 3046 if (!__test_and_clear_bit(0, (unsigned long *) 3047 &anon_vma->root->rb_root.rb_node)) 3048 BUG(); 3049 anon_vma_unlock_write(anon_vma); 3050 } 3051 } 3052 3053 static void vm_unlock_mapping(struct address_space *mapping) 3054 { 3055 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 3056 /* 3057 * AS_MM_ALL_LOCKS can't change to 0 from under us 3058 * because we hold the mm_all_locks_mutex. 3059 */ 3060 mutex_unlock(&mapping->i_mmap_mutex); 3061 if (!test_and_clear_bit(AS_MM_ALL_LOCKS, 3062 &mapping->flags)) 3063 BUG(); 3064 } 3065 } 3066 3067 /* 3068 * The mmap_sem cannot be released by the caller until 3069 * mm_drop_all_locks() returns. 3070 */ 3071 void mm_drop_all_locks(struct mm_struct *mm) 3072 { 3073 struct vm_area_struct *vma; 3074 struct anon_vma_chain *avc; 3075 3076 BUG_ON(down_read_trylock(&mm->mmap_sem)); 3077 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); 3078 3079 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3080 if (vma->anon_vma) 3081 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 3082 vm_unlock_anon_vma(avc->anon_vma); 3083 if (vma->vm_file && vma->vm_file->f_mapping) 3084 vm_unlock_mapping(vma->vm_file->f_mapping); 3085 } 3086 3087 mutex_unlock(&mm_all_locks_mutex); 3088 } 3089 3090 /* 3091 * initialise the VMA slab 3092 */ 3093 void __init mmap_init(void) 3094 { 3095 int ret; 3096 3097 ret = percpu_counter_init(&vm_committed_as, 0); 3098 VM_BUG_ON(ret); 3099 } 3100