1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * mm/mmap.c 4 * 5 * Written by obz. 6 * 7 * Address space accounting code <alan@lxorguk.ukuu.org.uk> 8 */ 9 10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 11 12 #include <linux/kernel.h> 13 #include <linux/slab.h> 14 #include <linux/backing-dev.h> 15 #include <linux/mm.h> 16 #include <linux/vmacache.h> 17 #include <linux/shm.h> 18 #include <linux/mman.h> 19 #include <linux/pagemap.h> 20 #include <linux/swap.h> 21 #include <linux/syscalls.h> 22 #include <linux/capability.h> 23 #include <linux/init.h> 24 #include <linux/file.h> 25 #include <linux/fs.h> 26 #include <linux/personality.h> 27 #include <linux/security.h> 28 #include <linux/hugetlb.h> 29 #include <linux/shmem_fs.h> 30 #include <linux/profile.h> 31 #include <linux/export.h> 32 #include <linux/mount.h> 33 #include <linux/mempolicy.h> 34 #include <linux/rmap.h> 35 #include <linux/mmu_notifier.h> 36 #include <linux/mmdebug.h> 37 #include <linux/perf_event.h> 38 #include <linux/audit.h> 39 #include <linux/khugepaged.h> 40 #include <linux/uprobes.h> 41 #include <linux/rbtree_augmented.h> 42 #include <linux/notifier.h> 43 #include <linux/memory.h> 44 #include <linux/printk.h> 45 #include <linux/userfaultfd_k.h> 46 #include <linux/moduleparam.h> 47 #include <linux/pkeys.h> 48 #include <linux/oom.h> 49 #include <linux/sched/mm.h> 50 51 #include <linux/uaccess.h> 52 #include <asm/cacheflush.h> 53 #include <asm/tlb.h> 54 #include <asm/mmu_context.h> 55 56 #define CREATE_TRACE_POINTS 57 #include <trace/events/mmap.h> 58 59 #include "internal.h" 60 61 #ifndef arch_mmap_check 62 #define arch_mmap_check(addr, len, flags) (0) 63 #endif 64 65 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS 66 const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN; 67 const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX; 68 int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS; 69 #endif 70 #ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS 71 const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN; 72 const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX; 73 int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS; 74 #endif 75 76 static bool ignore_rlimit_data; 77 core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644); 78 79 static void unmap_region(struct mm_struct *mm, 80 struct vm_area_struct *vma, struct vm_area_struct *prev, 81 unsigned long start, unsigned long end); 82 83 /* description of effects of mapping type and prot in current implementation. 84 * this is due to the limited x86 page protection hardware. The expected 85 * behavior is in parens: 86 * 87 * map_type prot 88 * PROT_NONE PROT_READ PROT_WRITE PROT_EXEC 89 * MAP_SHARED r: (no) no r: (yes) yes r: (no) yes r: (no) yes 90 * w: (no) no w: (no) no w: (yes) yes w: (no) no 91 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 92 * 93 * MAP_PRIVATE r: (no) no r: (yes) yes r: (no) yes r: (no) yes 94 * w: (no) no w: (no) no w: (copy) copy w: (no) no 95 * x: (no) no x: (no) yes x: (no) yes x: (yes) yes 96 */ 97 pgprot_t protection_map[16] __ro_after_init = { 98 __P000, __P001, __P010, __P011, __P100, __P101, __P110, __P111, 99 __S000, __S001, __S010, __S011, __S100, __S101, __S110, __S111 100 }; 101 102 #ifndef CONFIG_ARCH_HAS_FILTER_PGPROT 103 static inline pgprot_t arch_filter_pgprot(pgprot_t prot) 104 { 105 return prot; 106 } 107 #endif 108 109 pgprot_t vm_get_page_prot(unsigned long vm_flags) 110 { 111 pgprot_t ret = __pgprot(pgprot_val(protection_map[vm_flags & 112 (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)]) | 113 pgprot_val(arch_vm_get_page_prot(vm_flags))); 114 115 return arch_filter_pgprot(ret); 116 } 117 EXPORT_SYMBOL(vm_get_page_prot); 118 119 static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags) 120 { 121 return pgprot_modify(oldprot, vm_get_page_prot(vm_flags)); 122 } 123 124 /* Update vma->vm_page_prot to reflect vma->vm_flags. */ 125 void vma_set_page_prot(struct vm_area_struct *vma) 126 { 127 unsigned long vm_flags = vma->vm_flags; 128 pgprot_t vm_page_prot; 129 130 vm_page_prot = vm_pgprot_modify(vma->vm_page_prot, vm_flags); 131 if (vma_wants_writenotify(vma, vm_page_prot)) { 132 vm_flags &= ~VM_SHARED; 133 vm_page_prot = vm_pgprot_modify(vm_page_prot, vm_flags); 134 } 135 /* remove_protection_ptes reads vma->vm_page_prot without mmap_sem */ 136 WRITE_ONCE(vma->vm_page_prot, vm_page_prot); 137 } 138 139 /* 140 * Requires inode->i_mapping->i_mmap_rwsem 141 */ 142 static void __remove_shared_vm_struct(struct vm_area_struct *vma, 143 struct file *file, struct address_space *mapping) 144 { 145 if (vma->vm_flags & VM_DENYWRITE) 146 atomic_inc(&file_inode(file)->i_writecount); 147 if (vma->vm_flags & VM_SHARED) 148 mapping_unmap_writable(mapping); 149 150 flush_dcache_mmap_lock(mapping); 151 vma_interval_tree_remove(vma, &mapping->i_mmap); 152 flush_dcache_mmap_unlock(mapping); 153 } 154 155 /* 156 * Unlink a file-based vm structure from its interval tree, to hide 157 * vma from rmap and vmtruncate before freeing its page tables. 158 */ 159 void unlink_file_vma(struct vm_area_struct *vma) 160 { 161 struct file *file = vma->vm_file; 162 163 if (file) { 164 struct address_space *mapping = file->f_mapping; 165 i_mmap_lock_write(mapping); 166 __remove_shared_vm_struct(vma, file, mapping); 167 i_mmap_unlock_write(mapping); 168 } 169 } 170 171 /* 172 * Close a vm structure and free it, returning the next. 173 */ 174 static struct vm_area_struct *remove_vma(struct vm_area_struct *vma) 175 { 176 struct vm_area_struct *next = vma->vm_next; 177 178 might_sleep(); 179 if (vma->vm_ops && vma->vm_ops->close) 180 vma->vm_ops->close(vma); 181 if (vma->vm_file) 182 fput(vma->vm_file); 183 mpol_put(vma_policy(vma)); 184 vm_area_free(vma); 185 return next; 186 } 187 188 static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long flags, 189 struct list_head *uf); 190 SYSCALL_DEFINE1(brk, unsigned long, brk) 191 { 192 unsigned long retval; 193 unsigned long newbrk, oldbrk, origbrk; 194 struct mm_struct *mm = current->mm; 195 struct vm_area_struct *next; 196 unsigned long min_brk; 197 bool populate; 198 bool downgraded = false; 199 LIST_HEAD(uf); 200 201 if (down_write_killable(&mm->mmap_sem)) 202 return -EINTR; 203 204 origbrk = mm->brk; 205 206 #ifdef CONFIG_COMPAT_BRK 207 /* 208 * CONFIG_COMPAT_BRK can still be overridden by setting 209 * randomize_va_space to 2, which will still cause mm->start_brk 210 * to be arbitrarily shifted 211 */ 212 if (current->brk_randomized) 213 min_brk = mm->start_brk; 214 else 215 min_brk = mm->end_data; 216 #else 217 min_brk = mm->start_brk; 218 #endif 219 if (brk < min_brk) 220 goto out; 221 222 /* 223 * Check against rlimit here. If this check is done later after the test 224 * of oldbrk with newbrk then it can escape the test and let the data 225 * segment grow beyond its set limit the in case where the limit is 226 * not page aligned -Ram Gupta 227 */ 228 if (check_data_rlimit(rlimit(RLIMIT_DATA), brk, mm->start_brk, 229 mm->end_data, mm->start_data)) 230 goto out; 231 232 newbrk = PAGE_ALIGN(brk); 233 oldbrk = PAGE_ALIGN(mm->brk); 234 if (oldbrk == newbrk) { 235 mm->brk = brk; 236 goto success; 237 } 238 239 /* 240 * Always allow shrinking brk. 241 * __do_munmap() may downgrade mmap_sem to read. 242 */ 243 if (brk <= mm->brk) { 244 int ret; 245 246 /* 247 * mm->brk must to be protected by write mmap_sem so update it 248 * before downgrading mmap_sem. When __do_munmap() fails, 249 * mm->brk will be restored from origbrk. 250 */ 251 mm->brk = brk; 252 ret = __do_munmap(mm, newbrk, oldbrk-newbrk, &uf, true); 253 if (ret < 0) { 254 mm->brk = origbrk; 255 goto out; 256 } else if (ret == 1) { 257 downgraded = true; 258 } 259 goto success; 260 } 261 262 /* Check against existing mmap mappings. */ 263 next = find_vma(mm, oldbrk); 264 if (next && newbrk + PAGE_SIZE > vm_start_gap(next)) 265 goto out; 266 267 /* Ok, looks good - let it rip. */ 268 if (do_brk_flags(oldbrk, newbrk-oldbrk, 0, &uf) < 0) 269 goto out; 270 mm->brk = brk; 271 272 success: 273 populate = newbrk > oldbrk && (mm->def_flags & VM_LOCKED) != 0; 274 if (downgraded) 275 up_read(&mm->mmap_sem); 276 else 277 up_write(&mm->mmap_sem); 278 userfaultfd_unmap_complete(mm, &uf); 279 if (populate) 280 mm_populate(oldbrk, newbrk - oldbrk); 281 return brk; 282 283 out: 284 retval = origbrk; 285 up_write(&mm->mmap_sem); 286 return retval; 287 } 288 289 static inline unsigned long vma_compute_gap(struct vm_area_struct *vma) 290 { 291 unsigned long gap, prev_end; 292 293 /* 294 * Note: in the rare case of a VM_GROWSDOWN above a VM_GROWSUP, we 295 * allow two stack_guard_gaps between them here, and when choosing 296 * an unmapped area; whereas when expanding we only require one. 297 * That's a little inconsistent, but keeps the code here simpler. 298 */ 299 gap = vm_start_gap(vma); 300 if (vma->vm_prev) { 301 prev_end = vm_end_gap(vma->vm_prev); 302 if (gap > prev_end) 303 gap -= prev_end; 304 else 305 gap = 0; 306 } 307 return gap; 308 } 309 310 #ifdef CONFIG_DEBUG_VM_RB 311 static unsigned long vma_compute_subtree_gap(struct vm_area_struct *vma) 312 { 313 unsigned long max = vma_compute_gap(vma), subtree_gap; 314 if (vma->vm_rb.rb_left) { 315 subtree_gap = rb_entry(vma->vm_rb.rb_left, 316 struct vm_area_struct, vm_rb)->rb_subtree_gap; 317 if (subtree_gap > max) 318 max = subtree_gap; 319 } 320 if (vma->vm_rb.rb_right) { 321 subtree_gap = rb_entry(vma->vm_rb.rb_right, 322 struct vm_area_struct, vm_rb)->rb_subtree_gap; 323 if (subtree_gap > max) 324 max = subtree_gap; 325 } 326 return max; 327 } 328 329 static int browse_rb(struct mm_struct *mm) 330 { 331 struct rb_root *root = &mm->mm_rb; 332 int i = 0, j, bug = 0; 333 struct rb_node *nd, *pn = NULL; 334 unsigned long prev = 0, pend = 0; 335 336 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 337 struct vm_area_struct *vma; 338 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 339 if (vma->vm_start < prev) { 340 pr_emerg("vm_start %lx < prev %lx\n", 341 vma->vm_start, prev); 342 bug = 1; 343 } 344 if (vma->vm_start < pend) { 345 pr_emerg("vm_start %lx < pend %lx\n", 346 vma->vm_start, pend); 347 bug = 1; 348 } 349 if (vma->vm_start > vma->vm_end) { 350 pr_emerg("vm_start %lx > vm_end %lx\n", 351 vma->vm_start, vma->vm_end); 352 bug = 1; 353 } 354 spin_lock(&mm->page_table_lock); 355 if (vma->rb_subtree_gap != vma_compute_subtree_gap(vma)) { 356 pr_emerg("free gap %lx, correct %lx\n", 357 vma->rb_subtree_gap, 358 vma_compute_subtree_gap(vma)); 359 bug = 1; 360 } 361 spin_unlock(&mm->page_table_lock); 362 i++; 363 pn = nd; 364 prev = vma->vm_start; 365 pend = vma->vm_end; 366 } 367 j = 0; 368 for (nd = pn; nd; nd = rb_prev(nd)) 369 j++; 370 if (i != j) { 371 pr_emerg("backwards %d, forwards %d\n", j, i); 372 bug = 1; 373 } 374 return bug ? -1 : i; 375 } 376 377 static void validate_mm_rb(struct rb_root *root, struct vm_area_struct *ignore) 378 { 379 struct rb_node *nd; 380 381 for (nd = rb_first(root); nd; nd = rb_next(nd)) { 382 struct vm_area_struct *vma; 383 vma = rb_entry(nd, struct vm_area_struct, vm_rb); 384 VM_BUG_ON_VMA(vma != ignore && 385 vma->rb_subtree_gap != vma_compute_subtree_gap(vma), 386 vma); 387 } 388 } 389 390 static void validate_mm(struct mm_struct *mm) 391 { 392 int bug = 0; 393 int i = 0; 394 unsigned long highest_address = 0; 395 struct vm_area_struct *vma = mm->mmap; 396 397 while (vma) { 398 struct anon_vma *anon_vma = vma->anon_vma; 399 struct anon_vma_chain *avc; 400 401 if (anon_vma) { 402 anon_vma_lock_read(anon_vma); 403 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 404 anon_vma_interval_tree_verify(avc); 405 anon_vma_unlock_read(anon_vma); 406 } 407 408 highest_address = vm_end_gap(vma); 409 vma = vma->vm_next; 410 i++; 411 } 412 if (i != mm->map_count) { 413 pr_emerg("map_count %d vm_next %d\n", mm->map_count, i); 414 bug = 1; 415 } 416 if (highest_address != mm->highest_vm_end) { 417 pr_emerg("mm->highest_vm_end %lx, found %lx\n", 418 mm->highest_vm_end, highest_address); 419 bug = 1; 420 } 421 i = browse_rb(mm); 422 if (i != mm->map_count) { 423 if (i != -1) 424 pr_emerg("map_count %d rb %d\n", mm->map_count, i); 425 bug = 1; 426 } 427 VM_BUG_ON_MM(bug, mm); 428 } 429 #else 430 #define validate_mm_rb(root, ignore) do { } while (0) 431 #define validate_mm(mm) do { } while (0) 432 #endif 433 434 RB_DECLARE_CALLBACKS_MAX(static, vma_gap_callbacks, 435 struct vm_area_struct, vm_rb, 436 unsigned long, rb_subtree_gap, vma_compute_gap) 437 438 /* 439 * Update augmented rbtree rb_subtree_gap values after vma->vm_start or 440 * vma->vm_prev->vm_end values changed, without modifying the vma's position 441 * in the rbtree. 442 */ 443 static void vma_gap_update(struct vm_area_struct *vma) 444 { 445 /* 446 * As it turns out, RB_DECLARE_CALLBACKS_MAX() already created 447 * a callback function that does exactly what we want. 448 */ 449 vma_gap_callbacks_propagate(&vma->vm_rb, NULL); 450 } 451 452 static inline void vma_rb_insert(struct vm_area_struct *vma, 453 struct rb_root *root) 454 { 455 /* All rb_subtree_gap values must be consistent prior to insertion */ 456 validate_mm_rb(root, NULL); 457 458 rb_insert_augmented(&vma->vm_rb, root, &vma_gap_callbacks); 459 } 460 461 static void __vma_rb_erase(struct vm_area_struct *vma, struct rb_root *root) 462 { 463 /* 464 * Note rb_erase_augmented is a fairly large inline function, 465 * so make sure we instantiate it only once with our desired 466 * augmented rbtree callbacks. 467 */ 468 rb_erase_augmented(&vma->vm_rb, root, &vma_gap_callbacks); 469 } 470 471 static __always_inline void vma_rb_erase_ignore(struct vm_area_struct *vma, 472 struct rb_root *root, 473 struct vm_area_struct *ignore) 474 { 475 /* 476 * All rb_subtree_gap values must be consistent prior to erase, 477 * with the possible exception of the "next" vma being erased if 478 * next->vm_start was reduced. 479 */ 480 validate_mm_rb(root, ignore); 481 482 __vma_rb_erase(vma, root); 483 } 484 485 static __always_inline void vma_rb_erase(struct vm_area_struct *vma, 486 struct rb_root *root) 487 { 488 /* 489 * All rb_subtree_gap values must be consistent prior to erase, 490 * with the possible exception of the vma being erased. 491 */ 492 validate_mm_rb(root, vma); 493 494 __vma_rb_erase(vma, root); 495 } 496 497 /* 498 * vma has some anon_vma assigned, and is already inserted on that 499 * anon_vma's interval trees. 500 * 501 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the 502 * vma must be removed from the anon_vma's interval trees using 503 * anon_vma_interval_tree_pre_update_vma(). 504 * 505 * After the update, the vma will be reinserted using 506 * anon_vma_interval_tree_post_update_vma(). 507 * 508 * The entire update must be protected by exclusive mmap_sem and by 509 * the root anon_vma's mutex. 510 */ 511 static inline void 512 anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma) 513 { 514 struct anon_vma_chain *avc; 515 516 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 517 anon_vma_interval_tree_remove(avc, &avc->anon_vma->rb_root); 518 } 519 520 static inline void 521 anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma) 522 { 523 struct anon_vma_chain *avc; 524 525 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 526 anon_vma_interval_tree_insert(avc, &avc->anon_vma->rb_root); 527 } 528 529 static int find_vma_links(struct mm_struct *mm, unsigned long addr, 530 unsigned long end, struct vm_area_struct **pprev, 531 struct rb_node ***rb_link, struct rb_node **rb_parent) 532 { 533 struct rb_node **__rb_link, *__rb_parent, *rb_prev; 534 535 __rb_link = &mm->mm_rb.rb_node; 536 rb_prev = __rb_parent = NULL; 537 538 while (*__rb_link) { 539 struct vm_area_struct *vma_tmp; 540 541 __rb_parent = *__rb_link; 542 vma_tmp = rb_entry(__rb_parent, struct vm_area_struct, vm_rb); 543 544 if (vma_tmp->vm_end > addr) { 545 /* Fail if an existing vma overlaps the area */ 546 if (vma_tmp->vm_start < end) 547 return -ENOMEM; 548 __rb_link = &__rb_parent->rb_left; 549 } else { 550 rb_prev = __rb_parent; 551 __rb_link = &__rb_parent->rb_right; 552 } 553 } 554 555 *pprev = NULL; 556 if (rb_prev) 557 *pprev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 558 *rb_link = __rb_link; 559 *rb_parent = __rb_parent; 560 return 0; 561 } 562 563 static unsigned long count_vma_pages_range(struct mm_struct *mm, 564 unsigned long addr, unsigned long end) 565 { 566 unsigned long nr_pages = 0; 567 struct vm_area_struct *vma; 568 569 /* Find first overlaping mapping */ 570 vma = find_vma_intersection(mm, addr, end); 571 if (!vma) 572 return 0; 573 574 nr_pages = (min(end, vma->vm_end) - 575 max(addr, vma->vm_start)) >> PAGE_SHIFT; 576 577 /* Iterate over the rest of the overlaps */ 578 for (vma = vma->vm_next; vma; vma = vma->vm_next) { 579 unsigned long overlap_len; 580 581 if (vma->vm_start > end) 582 break; 583 584 overlap_len = min(end, vma->vm_end) - vma->vm_start; 585 nr_pages += overlap_len >> PAGE_SHIFT; 586 } 587 588 return nr_pages; 589 } 590 591 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma, 592 struct rb_node **rb_link, struct rb_node *rb_parent) 593 { 594 /* Update tracking information for the gap following the new vma. */ 595 if (vma->vm_next) 596 vma_gap_update(vma->vm_next); 597 else 598 mm->highest_vm_end = vm_end_gap(vma); 599 600 /* 601 * vma->vm_prev wasn't known when we followed the rbtree to find the 602 * correct insertion point for that vma. As a result, we could not 603 * update the vma vm_rb parents rb_subtree_gap values on the way down. 604 * So, we first insert the vma with a zero rb_subtree_gap value 605 * (to be consistent with what we did on the way down), and then 606 * immediately update the gap to the correct value. Finally we 607 * rebalance the rbtree after all augmented values have been set. 608 */ 609 rb_link_node(&vma->vm_rb, rb_parent, rb_link); 610 vma->rb_subtree_gap = 0; 611 vma_gap_update(vma); 612 vma_rb_insert(vma, &mm->mm_rb); 613 } 614 615 static void __vma_link_file(struct vm_area_struct *vma) 616 { 617 struct file *file; 618 619 file = vma->vm_file; 620 if (file) { 621 struct address_space *mapping = file->f_mapping; 622 623 if (vma->vm_flags & VM_DENYWRITE) 624 atomic_dec(&file_inode(file)->i_writecount); 625 if (vma->vm_flags & VM_SHARED) 626 atomic_inc(&mapping->i_mmap_writable); 627 628 flush_dcache_mmap_lock(mapping); 629 vma_interval_tree_insert(vma, &mapping->i_mmap); 630 flush_dcache_mmap_unlock(mapping); 631 } 632 } 633 634 static void 635 __vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 636 struct vm_area_struct *prev, struct rb_node **rb_link, 637 struct rb_node *rb_parent) 638 { 639 __vma_link_list(mm, vma, prev); 640 __vma_link_rb(mm, vma, rb_link, rb_parent); 641 } 642 643 static void vma_link(struct mm_struct *mm, struct vm_area_struct *vma, 644 struct vm_area_struct *prev, struct rb_node **rb_link, 645 struct rb_node *rb_parent) 646 { 647 struct address_space *mapping = NULL; 648 649 if (vma->vm_file) { 650 mapping = vma->vm_file->f_mapping; 651 i_mmap_lock_write(mapping); 652 } 653 654 __vma_link(mm, vma, prev, rb_link, rb_parent); 655 __vma_link_file(vma); 656 657 if (mapping) 658 i_mmap_unlock_write(mapping); 659 660 mm->map_count++; 661 validate_mm(mm); 662 } 663 664 /* 665 * Helper for vma_adjust() in the split_vma insert case: insert a vma into the 666 * mm's list and rbtree. It has already been inserted into the interval tree. 667 */ 668 static void __insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 669 { 670 struct vm_area_struct *prev; 671 struct rb_node **rb_link, *rb_parent; 672 673 if (find_vma_links(mm, vma->vm_start, vma->vm_end, 674 &prev, &rb_link, &rb_parent)) 675 BUG(); 676 __vma_link(mm, vma, prev, rb_link, rb_parent); 677 mm->map_count++; 678 } 679 680 static __always_inline void __vma_unlink_common(struct mm_struct *mm, 681 struct vm_area_struct *vma, 682 struct vm_area_struct *ignore) 683 { 684 vma_rb_erase_ignore(vma, &mm->mm_rb, ignore); 685 __vma_unlink_list(mm, vma); 686 /* Kill the cache */ 687 vmacache_invalidate(mm); 688 } 689 690 /* 691 * We cannot adjust vm_start, vm_end, vm_pgoff fields of a vma that 692 * is already present in an i_mmap tree without adjusting the tree. 693 * The following helper function should be used when such adjustments 694 * are necessary. The "insert" vma (if any) is to be inserted 695 * before we drop the necessary locks. 696 */ 697 int __vma_adjust(struct vm_area_struct *vma, unsigned long start, 698 unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert, 699 struct vm_area_struct *expand) 700 { 701 struct mm_struct *mm = vma->vm_mm; 702 struct vm_area_struct *next = vma->vm_next, *orig_vma = vma; 703 struct address_space *mapping = NULL; 704 struct rb_root_cached *root = NULL; 705 struct anon_vma *anon_vma = NULL; 706 struct file *file = vma->vm_file; 707 bool start_changed = false, end_changed = false; 708 long adjust_next = 0; 709 int remove_next = 0; 710 711 if (next && !insert) { 712 struct vm_area_struct *exporter = NULL, *importer = NULL; 713 714 if (end >= next->vm_end) { 715 /* 716 * vma expands, overlapping all the next, and 717 * perhaps the one after too (mprotect case 6). 718 * The only other cases that gets here are 719 * case 1, case 7 and case 8. 720 */ 721 if (next == expand) { 722 /* 723 * The only case where we don't expand "vma" 724 * and we expand "next" instead is case 8. 725 */ 726 VM_WARN_ON(end != next->vm_end); 727 /* 728 * remove_next == 3 means we're 729 * removing "vma" and that to do so we 730 * swapped "vma" and "next". 731 */ 732 remove_next = 3; 733 VM_WARN_ON(file != next->vm_file); 734 swap(vma, next); 735 } else { 736 VM_WARN_ON(expand != vma); 737 /* 738 * case 1, 6, 7, remove_next == 2 is case 6, 739 * remove_next == 1 is case 1 or 7. 740 */ 741 remove_next = 1 + (end > next->vm_end); 742 VM_WARN_ON(remove_next == 2 && 743 end != next->vm_next->vm_end); 744 /* trim end to next, for case 6 first pass */ 745 end = next->vm_end; 746 } 747 748 exporter = next; 749 importer = vma; 750 751 /* 752 * If next doesn't have anon_vma, import from vma after 753 * next, if the vma overlaps with it. 754 */ 755 if (remove_next == 2 && !next->anon_vma) 756 exporter = next->vm_next; 757 758 } else if (end > next->vm_start) { 759 /* 760 * vma expands, overlapping part of the next: 761 * mprotect case 5 shifting the boundary up. 762 */ 763 adjust_next = (end - next->vm_start) >> PAGE_SHIFT; 764 exporter = next; 765 importer = vma; 766 VM_WARN_ON(expand != importer); 767 } else if (end < vma->vm_end) { 768 /* 769 * vma shrinks, and !insert tells it's not 770 * split_vma inserting another: so it must be 771 * mprotect case 4 shifting the boundary down. 772 */ 773 adjust_next = -((vma->vm_end - end) >> PAGE_SHIFT); 774 exporter = vma; 775 importer = next; 776 VM_WARN_ON(expand != importer); 777 } 778 779 /* 780 * Easily overlooked: when mprotect shifts the boundary, 781 * make sure the expanding vma has anon_vma set if the 782 * shrinking vma had, to cover any anon pages imported. 783 */ 784 if (exporter && exporter->anon_vma && !importer->anon_vma) { 785 int error; 786 787 importer->anon_vma = exporter->anon_vma; 788 error = anon_vma_clone(importer, exporter); 789 if (error) 790 return error; 791 } 792 } 793 again: 794 vma_adjust_trans_huge(orig_vma, start, end, adjust_next); 795 796 if (file) { 797 mapping = file->f_mapping; 798 root = &mapping->i_mmap; 799 uprobe_munmap(vma, vma->vm_start, vma->vm_end); 800 801 if (adjust_next) 802 uprobe_munmap(next, next->vm_start, next->vm_end); 803 804 i_mmap_lock_write(mapping); 805 if (insert) { 806 /* 807 * Put into interval tree now, so instantiated pages 808 * are visible to arm/parisc __flush_dcache_page 809 * throughout; but we cannot insert into address 810 * space until vma start or end is updated. 811 */ 812 __vma_link_file(insert); 813 } 814 } 815 816 anon_vma = vma->anon_vma; 817 if (!anon_vma && adjust_next) 818 anon_vma = next->anon_vma; 819 if (anon_vma) { 820 VM_WARN_ON(adjust_next && next->anon_vma && 821 anon_vma != next->anon_vma); 822 anon_vma_lock_write(anon_vma); 823 anon_vma_interval_tree_pre_update_vma(vma); 824 if (adjust_next) 825 anon_vma_interval_tree_pre_update_vma(next); 826 } 827 828 if (root) { 829 flush_dcache_mmap_lock(mapping); 830 vma_interval_tree_remove(vma, root); 831 if (adjust_next) 832 vma_interval_tree_remove(next, root); 833 } 834 835 if (start != vma->vm_start) { 836 vma->vm_start = start; 837 start_changed = true; 838 } 839 if (end != vma->vm_end) { 840 vma->vm_end = end; 841 end_changed = true; 842 } 843 vma->vm_pgoff = pgoff; 844 if (adjust_next) { 845 next->vm_start += adjust_next << PAGE_SHIFT; 846 next->vm_pgoff += adjust_next; 847 } 848 849 if (root) { 850 if (adjust_next) 851 vma_interval_tree_insert(next, root); 852 vma_interval_tree_insert(vma, root); 853 flush_dcache_mmap_unlock(mapping); 854 } 855 856 if (remove_next) { 857 /* 858 * vma_merge has merged next into vma, and needs 859 * us to remove next before dropping the locks. 860 */ 861 if (remove_next != 3) 862 __vma_unlink_common(mm, next, next); 863 else 864 /* 865 * vma is not before next if they've been 866 * swapped. 867 * 868 * pre-swap() next->vm_start was reduced so 869 * tell validate_mm_rb to ignore pre-swap() 870 * "next" (which is stored in post-swap() 871 * "vma"). 872 */ 873 __vma_unlink_common(mm, next, vma); 874 if (file) 875 __remove_shared_vm_struct(next, file, mapping); 876 } else if (insert) { 877 /* 878 * split_vma has split insert from vma, and needs 879 * us to insert it before dropping the locks 880 * (it may either follow vma or precede it). 881 */ 882 __insert_vm_struct(mm, insert); 883 } else { 884 if (start_changed) 885 vma_gap_update(vma); 886 if (end_changed) { 887 if (!next) 888 mm->highest_vm_end = vm_end_gap(vma); 889 else if (!adjust_next) 890 vma_gap_update(next); 891 } 892 } 893 894 if (anon_vma) { 895 anon_vma_interval_tree_post_update_vma(vma); 896 if (adjust_next) 897 anon_vma_interval_tree_post_update_vma(next); 898 anon_vma_unlock_write(anon_vma); 899 } 900 if (mapping) 901 i_mmap_unlock_write(mapping); 902 903 if (root) { 904 uprobe_mmap(vma); 905 906 if (adjust_next) 907 uprobe_mmap(next); 908 } 909 910 if (remove_next) { 911 if (file) { 912 uprobe_munmap(next, next->vm_start, next->vm_end); 913 fput(file); 914 } 915 if (next->anon_vma) 916 anon_vma_merge(vma, next); 917 mm->map_count--; 918 mpol_put(vma_policy(next)); 919 vm_area_free(next); 920 /* 921 * In mprotect's case 6 (see comments on vma_merge), 922 * we must remove another next too. It would clutter 923 * up the code too much to do both in one go. 924 */ 925 if (remove_next != 3) { 926 /* 927 * If "next" was removed and vma->vm_end was 928 * expanded (up) over it, in turn 929 * "next->vm_prev->vm_end" changed and the 930 * "vma->vm_next" gap must be updated. 931 */ 932 next = vma->vm_next; 933 } else { 934 /* 935 * For the scope of the comment "next" and 936 * "vma" considered pre-swap(): if "vma" was 937 * removed, next->vm_start was expanded (down) 938 * over it and the "next" gap must be updated. 939 * Because of the swap() the post-swap() "vma" 940 * actually points to pre-swap() "next" 941 * (post-swap() "next" as opposed is now a 942 * dangling pointer). 943 */ 944 next = vma; 945 } 946 if (remove_next == 2) { 947 remove_next = 1; 948 end = next->vm_end; 949 goto again; 950 } 951 else if (next) 952 vma_gap_update(next); 953 else { 954 /* 955 * If remove_next == 2 we obviously can't 956 * reach this path. 957 * 958 * If remove_next == 3 we can't reach this 959 * path because pre-swap() next is always not 960 * NULL. pre-swap() "next" is not being 961 * removed and its next->vm_end is not altered 962 * (and furthermore "end" already matches 963 * next->vm_end in remove_next == 3). 964 * 965 * We reach this only in the remove_next == 1 966 * case if the "next" vma that was removed was 967 * the highest vma of the mm. However in such 968 * case next->vm_end == "end" and the extended 969 * "vma" has vma->vm_end == next->vm_end so 970 * mm->highest_vm_end doesn't need any update 971 * in remove_next == 1 case. 972 */ 973 VM_WARN_ON(mm->highest_vm_end != vm_end_gap(vma)); 974 } 975 } 976 if (insert && file) 977 uprobe_mmap(insert); 978 979 validate_mm(mm); 980 981 return 0; 982 } 983 984 /* 985 * If the vma has a ->close operation then the driver probably needs to release 986 * per-vma resources, so we don't attempt to merge those. 987 */ 988 static inline int is_mergeable_vma(struct vm_area_struct *vma, 989 struct file *file, unsigned long vm_flags, 990 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 991 { 992 /* 993 * VM_SOFTDIRTY should not prevent from VMA merging, if we 994 * match the flags but dirty bit -- the caller should mark 995 * merged VMA as dirty. If dirty bit won't be excluded from 996 * comparison, we increase pressure on the memory system forcing 997 * the kernel to generate new VMAs when old one could be 998 * extended instead. 999 */ 1000 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY) 1001 return 0; 1002 if (vma->vm_file != file) 1003 return 0; 1004 if (vma->vm_ops && vma->vm_ops->close) 1005 return 0; 1006 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_userfaultfd_ctx)) 1007 return 0; 1008 return 1; 1009 } 1010 1011 static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1, 1012 struct anon_vma *anon_vma2, 1013 struct vm_area_struct *vma) 1014 { 1015 /* 1016 * The list_is_singular() test is to avoid merging VMA cloned from 1017 * parents. This can improve scalability caused by anon_vma lock. 1018 */ 1019 if ((!anon_vma1 || !anon_vma2) && (!vma || 1020 list_is_singular(&vma->anon_vma_chain))) 1021 return 1; 1022 return anon_vma1 == anon_vma2; 1023 } 1024 1025 /* 1026 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 1027 * in front of (at a lower virtual address and file offset than) the vma. 1028 * 1029 * We cannot merge two vmas if they have differently assigned (non-NULL) 1030 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 1031 * 1032 * We don't check here for the merged mmap wrapping around the end of pagecache 1033 * indices (16TB on ia32) because do_mmap_pgoff() does not permit mmap's which 1034 * wrap, nor mmaps which cover the final page at index -1UL. 1035 */ 1036 static int 1037 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags, 1038 struct anon_vma *anon_vma, struct file *file, 1039 pgoff_t vm_pgoff, 1040 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 1041 { 1042 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && 1043 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { 1044 if (vma->vm_pgoff == vm_pgoff) 1045 return 1; 1046 } 1047 return 0; 1048 } 1049 1050 /* 1051 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff) 1052 * beyond (at a higher virtual address and file offset than) the vma. 1053 * 1054 * We cannot merge two vmas if they have differently assigned (non-NULL) 1055 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible. 1056 */ 1057 static int 1058 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags, 1059 struct anon_vma *anon_vma, struct file *file, 1060 pgoff_t vm_pgoff, 1061 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 1062 { 1063 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx) && 1064 is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { 1065 pgoff_t vm_pglen; 1066 vm_pglen = vma_pages(vma); 1067 if (vma->vm_pgoff + vm_pglen == vm_pgoff) 1068 return 1; 1069 } 1070 return 0; 1071 } 1072 1073 /* 1074 * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out 1075 * whether that can be merged with its predecessor or its successor. 1076 * Or both (it neatly fills a hole). 1077 * 1078 * In most cases - when called for mmap, brk or mremap - [addr,end) is 1079 * certain not to be mapped by the time vma_merge is called; but when 1080 * called for mprotect, it is certain to be already mapped (either at 1081 * an offset within prev, or at the start of next), and the flags of 1082 * this area are about to be changed to vm_flags - and the no-change 1083 * case has already been eliminated. 1084 * 1085 * The following mprotect cases have to be considered, where AAAA is 1086 * the area passed down from mprotect_fixup, never extending beyond one 1087 * vma, PPPPPP is the prev vma specified, and NNNNNN the next vma after: 1088 * 1089 * AAAA AAAA AAAA 1090 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPNNNNNN 1091 * cannot merge might become might become 1092 * PPNNNNNNNNNN PPPPPPPPPPNN 1093 * mmap, brk or case 4 below case 5 below 1094 * mremap move: 1095 * AAAA AAAA 1096 * PPPP NNNN PPPPNNNNXXXX 1097 * might become might become 1098 * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or 1099 * PPPPPPPPNNNN 2 or PPPPPPPPXXXX 7 or 1100 * PPPPNNNNNNNN 3 PPPPXXXXXXXX 8 1101 * 1102 * It is important for case 8 that the vma NNNN overlapping the 1103 * region AAAA is never going to extended over XXXX. Instead XXXX must 1104 * be extended in region AAAA and NNNN must be removed. This way in 1105 * all cases where vma_merge succeeds, the moment vma_adjust drops the 1106 * rmap_locks, the properties of the merged vma will be already 1107 * correct for the whole merged range. Some of those properties like 1108 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must 1109 * be correct for the whole merged range immediately after the 1110 * rmap_locks are released. Otherwise if XXXX would be removed and 1111 * NNNN would be extended over the XXXX range, remove_migration_ptes 1112 * or other rmap walkers (if working on addresses beyond the "end" 1113 * parameter) may establish ptes with the wrong permissions of NNNN 1114 * instead of the right permissions of XXXX. 1115 */ 1116 struct vm_area_struct *vma_merge(struct mm_struct *mm, 1117 struct vm_area_struct *prev, unsigned long addr, 1118 unsigned long end, unsigned long vm_flags, 1119 struct anon_vma *anon_vma, struct file *file, 1120 pgoff_t pgoff, struct mempolicy *policy, 1121 struct vm_userfaultfd_ctx vm_userfaultfd_ctx) 1122 { 1123 pgoff_t pglen = (end - addr) >> PAGE_SHIFT; 1124 struct vm_area_struct *area, *next; 1125 int err; 1126 1127 /* 1128 * We later require that vma->vm_flags == vm_flags, 1129 * so this tests vma->vm_flags & VM_SPECIAL, too. 1130 */ 1131 if (vm_flags & VM_SPECIAL) 1132 return NULL; 1133 1134 if (prev) 1135 next = prev->vm_next; 1136 else 1137 next = mm->mmap; 1138 area = next; 1139 if (area && area->vm_end == end) /* cases 6, 7, 8 */ 1140 next = next->vm_next; 1141 1142 /* verify some invariant that must be enforced by the caller */ 1143 VM_WARN_ON(prev && addr <= prev->vm_start); 1144 VM_WARN_ON(area && end > area->vm_end); 1145 VM_WARN_ON(addr >= end); 1146 1147 /* 1148 * Can it merge with the predecessor? 1149 */ 1150 if (prev && prev->vm_end == addr && 1151 mpol_equal(vma_policy(prev), policy) && 1152 can_vma_merge_after(prev, vm_flags, 1153 anon_vma, file, pgoff, 1154 vm_userfaultfd_ctx)) { 1155 /* 1156 * OK, it can. Can we now merge in the successor as well? 1157 */ 1158 if (next && end == next->vm_start && 1159 mpol_equal(policy, vma_policy(next)) && 1160 can_vma_merge_before(next, vm_flags, 1161 anon_vma, file, 1162 pgoff+pglen, 1163 vm_userfaultfd_ctx) && 1164 is_mergeable_anon_vma(prev->anon_vma, 1165 next->anon_vma, NULL)) { 1166 /* cases 1, 6 */ 1167 err = __vma_adjust(prev, prev->vm_start, 1168 next->vm_end, prev->vm_pgoff, NULL, 1169 prev); 1170 } else /* cases 2, 5, 7 */ 1171 err = __vma_adjust(prev, prev->vm_start, 1172 end, prev->vm_pgoff, NULL, prev); 1173 if (err) 1174 return NULL; 1175 khugepaged_enter_vma_merge(prev, vm_flags); 1176 return prev; 1177 } 1178 1179 /* 1180 * Can this new request be merged in front of next? 1181 */ 1182 if (next && end == next->vm_start && 1183 mpol_equal(policy, vma_policy(next)) && 1184 can_vma_merge_before(next, vm_flags, 1185 anon_vma, file, pgoff+pglen, 1186 vm_userfaultfd_ctx)) { 1187 if (prev && addr < prev->vm_end) /* case 4 */ 1188 err = __vma_adjust(prev, prev->vm_start, 1189 addr, prev->vm_pgoff, NULL, next); 1190 else { /* cases 3, 8 */ 1191 err = __vma_adjust(area, addr, next->vm_end, 1192 next->vm_pgoff - pglen, NULL, next); 1193 /* 1194 * In case 3 area is already equal to next and 1195 * this is a noop, but in case 8 "area" has 1196 * been removed and next was expanded over it. 1197 */ 1198 area = next; 1199 } 1200 if (err) 1201 return NULL; 1202 khugepaged_enter_vma_merge(area, vm_flags); 1203 return area; 1204 } 1205 1206 return NULL; 1207 } 1208 1209 /* 1210 * Rough compatbility check to quickly see if it's even worth looking 1211 * at sharing an anon_vma. 1212 * 1213 * They need to have the same vm_file, and the flags can only differ 1214 * in things that mprotect may change. 1215 * 1216 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that 1217 * we can merge the two vma's. For example, we refuse to merge a vma if 1218 * there is a vm_ops->close() function, because that indicates that the 1219 * driver is doing some kind of reference counting. But that doesn't 1220 * really matter for the anon_vma sharing case. 1221 */ 1222 static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b) 1223 { 1224 return a->vm_end == b->vm_start && 1225 mpol_equal(vma_policy(a), vma_policy(b)) && 1226 a->vm_file == b->vm_file && 1227 !((a->vm_flags ^ b->vm_flags) & ~(VM_READ|VM_WRITE|VM_EXEC|VM_SOFTDIRTY)) && 1228 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT); 1229 } 1230 1231 /* 1232 * Do some basic sanity checking to see if we can re-use the anon_vma 1233 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be 1234 * the same as 'old', the other will be the new one that is trying 1235 * to share the anon_vma. 1236 * 1237 * NOTE! This runs with mm_sem held for reading, so it is possible that 1238 * the anon_vma of 'old' is concurrently in the process of being set up 1239 * by another page fault trying to merge _that_. But that's ok: if it 1240 * is being set up, that automatically means that it will be a singleton 1241 * acceptable for merging, so we can do all of this optimistically. But 1242 * we do that READ_ONCE() to make sure that we never re-load the pointer. 1243 * 1244 * IOW: that the "list_is_singular()" test on the anon_vma_chain only 1245 * matters for the 'stable anon_vma' case (ie the thing we want to avoid 1246 * is to return an anon_vma that is "complex" due to having gone through 1247 * a fork). 1248 * 1249 * We also make sure that the two vma's are compatible (adjacent, 1250 * and with the same memory policies). That's all stable, even with just 1251 * a read lock on the mm_sem. 1252 */ 1253 static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b) 1254 { 1255 if (anon_vma_compatible(a, b)) { 1256 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma); 1257 1258 if (anon_vma && list_is_singular(&old->anon_vma_chain)) 1259 return anon_vma; 1260 } 1261 return NULL; 1262 } 1263 1264 /* 1265 * find_mergeable_anon_vma is used by anon_vma_prepare, to check 1266 * neighbouring vmas for a suitable anon_vma, before it goes off 1267 * to allocate a new anon_vma. It checks because a repetitive 1268 * sequence of mprotects and faults may otherwise lead to distinct 1269 * anon_vmas being allocated, preventing vma merge in subsequent 1270 * mprotect. 1271 */ 1272 struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma) 1273 { 1274 struct anon_vma *anon_vma = NULL; 1275 1276 /* Try next first. */ 1277 if (vma->vm_next) { 1278 anon_vma = reusable_anon_vma(vma->vm_next, vma, vma->vm_next); 1279 if (anon_vma) 1280 return anon_vma; 1281 } 1282 1283 /* Try prev next. */ 1284 if (vma->vm_prev) 1285 anon_vma = reusable_anon_vma(vma->vm_prev, vma->vm_prev, vma); 1286 1287 /* 1288 * We might reach here with anon_vma == NULL if we can't find 1289 * any reusable anon_vma. 1290 * There's no absolute need to look only at touching neighbours: 1291 * we could search further afield for "compatible" anon_vmas. 1292 * But it would probably just be a waste of time searching, 1293 * or lead to too many vmas hanging off the same anon_vma. 1294 * We're trying to allow mprotect remerging later on, 1295 * not trying to minimize memory used for anon_vmas. 1296 */ 1297 return anon_vma; 1298 } 1299 1300 /* 1301 * If a hint addr is less than mmap_min_addr change hint to be as 1302 * low as possible but still greater than mmap_min_addr 1303 */ 1304 static inline unsigned long round_hint_to_min(unsigned long hint) 1305 { 1306 hint &= PAGE_MASK; 1307 if (((void *)hint != NULL) && 1308 (hint < mmap_min_addr)) 1309 return PAGE_ALIGN(mmap_min_addr); 1310 return hint; 1311 } 1312 1313 static inline int mlock_future_check(struct mm_struct *mm, 1314 unsigned long flags, 1315 unsigned long len) 1316 { 1317 unsigned long locked, lock_limit; 1318 1319 /* mlock MCL_FUTURE? */ 1320 if (flags & VM_LOCKED) { 1321 locked = len >> PAGE_SHIFT; 1322 locked += mm->locked_vm; 1323 lock_limit = rlimit(RLIMIT_MEMLOCK); 1324 lock_limit >>= PAGE_SHIFT; 1325 if (locked > lock_limit && !capable(CAP_IPC_LOCK)) 1326 return -EAGAIN; 1327 } 1328 return 0; 1329 } 1330 1331 static inline u64 file_mmap_size_max(struct file *file, struct inode *inode) 1332 { 1333 if (S_ISREG(inode->i_mode)) 1334 return MAX_LFS_FILESIZE; 1335 1336 if (S_ISBLK(inode->i_mode)) 1337 return MAX_LFS_FILESIZE; 1338 1339 if (S_ISSOCK(inode->i_mode)) 1340 return MAX_LFS_FILESIZE; 1341 1342 /* Special "we do even unsigned file positions" case */ 1343 if (file->f_mode & FMODE_UNSIGNED_OFFSET) 1344 return 0; 1345 1346 /* Yes, random drivers might want more. But I'm tired of buggy drivers */ 1347 return ULONG_MAX; 1348 } 1349 1350 static inline bool file_mmap_ok(struct file *file, struct inode *inode, 1351 unsigned long pgoff, unsigned long len) 1352 { 1353 u64 maxsize = file_mmap_size_max(file, inode); 1354 1355 if (maxsize && len > maxsize) 1356 return false; 1357 maxsize -= len; 1358 if (pgoff > maxsize >> PAGE_SHIFT) 1359 return false; 1360 return true; 1361 } 1362 1363 /* 1364 * The caller must hold down_write(¤t->mm->mmap_sem). 1365 */ 1366 unsigned long do_mmap(struct file *file, unsigned long addr, 1367 unsigned long len, unsigned long prot, 1368 unsigned long flags, vm_flags_t vm_flags, 1369 unsigned long pgoff, unsigned long *populate, 1370 struct list_head *uf) 1371 { 1372 struct mm_struct *mm = current->mm; 1373 int pkey = 0; 1374 1375 *populate = 0; 1376 1377 if (!len) 1378 return -EINVAL; 1379 1380 /* 1381 * Does the application expect PROT_READ to imply PROT_EXEC? 1382 * 1383 * (the exception is when the underlying filesystem is noexec 1384 * mounted, in which case we dont add PROT_EXEC.) 1385 */ 1386 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) 1387 if (!(file && path_noexec(&file->f_path))) 1388 prot |= PROT_EXEC; 1389 1390 /* force arch specific MAP_FIXED handling in get_unmapped_area */ 1391 if (flags & MAP_FIXED_NOREPLACE) 1392 flags |= MAP_FIXED; 1393 1394 if (!(flags & MAP_FIXED)) 1395 addr = round_hint_to_min(addr); 1396 1397 /* Careful about overflows.. */ 1398 len = PAGE_ALIGN(len); 1399 if (!len) 1400 return -ENOMEM; 1401 1402 /* offset overflow? */ 1403 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff) 1404 return -EOVERFLOW; 1405 1406 /* Too many mappings? */ 1407 if (mm->map_count > sysctl_max_map_count) 1408 return -ENOMEM; 1409 1410 /* Obtain the address to map to. we verify (or select) it and ensure 1411 * that it represents a valid section of the address space. 1412 */ 1413 addr = get_unmapped_area(file, addr, len, pgoff, flags); 1414 if (IS_ERR_VALUE(addr)) 1415 return addr; 1416 1417 if (flags & MAP_FIXED_NOREPLACE) { 1418 struct vm_area_struct *vma = find_vma(mm, addr); 1419 1420 if (vma && vma->vm_start < addr + len) 1421 return -EEXIST; 1422 } 1423 1424 if (prot == PROT_EXEC) { 1425 pkey = execute_only_pkey(mm); 1426 if (pkey < 0) 1427 pkey = 0; 1428 } 1429 1430 /* Do simple checking here so the lower-level routines won't have 1431 * to. we assume access permissions have been handled by the open 1432 * of the memory object, so we don't do any here. 1433 */ 1434 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) | 1435 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1436 1437 if (flags & MAP_LOCKED) 1438 if (!can_do_mlock()) 1439 return -EPERM; 1440 1441 if (mlock_future_check(mm, vm_flags, len)) 1442 return -EAGAIN; 1443 1444 if (file) { 1445 struct inode *inode = file_inode(file); 1446 unsigned long flags_mask; 1447 1448 if (!file_mmap_ok(file, inode, pgoff, len)) 1449 return -EOVERFLOW; 1450 1451 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; 1452 1453 switch (flags & MAP_TYPE) { 1454 case MAP_SHARED: 1455 /* 1456 * Force use of MAP_SHARED_VALIDATE with non-legacy 1457 * flags. E.g. MAP_SYNC is dangerous to use with 1458 * MAP_SHARED as you don't know which consistency model 1459 * you will get. We silently ignore unsupported flags 1460 * with MAP_SHARED to preserve backward compatibility. 1461 */ 1462 flags &= LEGACY_MAP_MASK; 1463 fallthrough; 1464 case MAP_SHARED_VALIDATE: 1465 if (flags & ~flags_mask) 1466 return -EOPNOTSUPP; 1467 if (prot & PROT_WRITE) { 1468 if (!(file->f_mode & FMODE_WRITE)) 1469 return -EACCES; 1470 if (IS_SWAPFILE(file->f_mapping->host)) 1471 return -ETXTBSY; 1472 } 1473 1474 /* 1475 * Make sure we don't allow writing to an append-only 1476 * file.. 1477 */ 1478 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE)) 1479 return -EACCES; 1480 1481 /* 1482 * Make sure there are no mandatory locks on the file. 1483 */ 1484 if (locks_verify_locked(file)) 1485 return -EAGAIN; 1486 1487 vm_flags |= VM_SHARED | VM_MAYSHARE; 1488 if (!(file->f_mode & FMODE_WRITE)) 1489 vm_flags &= ~(VM_MAYWRITE | VM_SHARED); 1490 fallthrough; 1491 case MAP_PRIVATE: 1492 if (!(file->f_mode & FMODE_READ)) 1493 return -EACCES; 1494 if (path_noexec(&file->f_path)) { 1495 if (vm_flags & VM_EXEC) 1496 return -EPERM; 1497 vm_flags &= ~VM_MAYEXEC; 1498 } 1499 1500 if (!file->f_op->mmap) 1501 return -ENODEV; 1502 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1503 return -EINVAL; 1504 break; 1505 1506 default: 1507 return -EINVAL; 1508 } 1509 } else { 1510 switch (flags & MAP_TYPE) { 1511 case MAP_SHARED: 1512 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) 1513 return -EINVAL; 1514 /* 1515 * Ignore pgoff. 1516 */ 1517 pgoff = 0; 1518 vm_flags |= VM_SHARED | VM_MAYSHARE; 1519 break; 1520 case MAP_PRIVATE: 1521 /* 1522 * Set pgoff according to addr for anon_vma. 1523 */ 1524 pgoff = addr >> PAGE_SHIFT; 1525 break; 1526 default: 1527 return -EINVAL; 1528 } 1529 } 1530 1531 /* 1532 * Set 'VM_NORESERVE' if we should not account for the 1533 * memory use of this mapping. 1534 */ 1535 if (flags & MAP_NORESERVE) { 1536 /* We honor MAP_NORESERVE if allowed to overcommit */ 1537 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER) 1538 vm_flags |= VM_NORESERVE; 1539 1540 /* hugetlb applies strict overcommit unless MAP_NORESERVE */ 1541 if (file && is_file_hugepages(file)) 1542 vm_flags |= VM_NORESERVE; 1543 } 1544 1545 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf); 1546 if (!IS_ERR_VALUE(addr) && 1547 ((vm_flags & VM_LOCKED) || 1548 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE)) 1549 *populate = len; 1550 return addr; 1551 } 1552 1553 unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, 1554 unsigned long prot, unsigned long flags, 1555 unsigned long fd, unsigned long pgoff) 1556 { 1557 struct file *file = NULL; 1558 unsigned long retval; 1559 1560 if (!(flags & MAP_ANONYMOUS)) { 1561 audit_mmap_fd(fd, flags); 1562 file = fget(fd); 1563 if (!file) 1564 return -EBADF; 1565 if (is_file_hugepages(file)) 1566 len = ALIGN(len, huge_page_size(hstate_file(file))); 1567 retval = -EINVAL; 1568 if (unlikely(flags & MAP_HUGETLB && !is_file_hugepages(file))) 1569 goto out_fput; 1570 } else if (flags & MAP_HUGETLB) { 1571 struct user_struct *user = NULL; 1572 struct hstate *hs; 1573 1574 hs = hstate_sizelog((flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); 1575 if (!hs) 1576 return -EINVAL; 1577 1578 len = ALIGN(len, huge_page_size(hs)); 1579 /* 1580 * VM_NORESERVE is used because the reservations will be 1581 * taken when vm_ops->mmap() is called 1582 * A dummy user value is used because we are not locking 1583 * memory so no accounting is necessary 1584 */ 1585 file = hugetlb_file_setup(HUGETLB_ANON_FILE, len, 1586 VM_NORESERVE, 1587 &user, HUGETLB_ANONHUGE_INODE, 1588 (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK); 1589 if (IS_ERR(file)) 1590 return PTR_ERR(file); 1591 } 1592 1593 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1594 1595 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1596 out_fput: 1597 if (file) 1598 fput(file); 1599 return retval; 1600 } 1601 1602 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1603 unsigned long, prot, unsigned long, flags, 1604 unsigned long, fd, unsigned long, pgoff) 1605 { 1606 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); 1607 } 1608 1609 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1610 struct mmap_arg_struct { 1611 unsigned long addr; 1612 unsigned long len; 1613 unsigned long prot; 1614 unsigned long flags; 1615 unsigned long fd; 1616 unsigned long offset; 1617 }; 1618 1619 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1620 { 1621 struct mmap_arg_struct a; 1622 1623 if (copy_from_user(&a, arg, sizeof(a))) 1624 return -EFAULT; 1625 if (offset_in_page(a.offset)) 1626 return -EINVAL; 1627 1628 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1629 a.offset >> PAGE_SHIFT); 1630 } 1631 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1632 1633 /* 1634 * Some shared mappings will want the pages marked read-only 1635 * to track write events. If so, we'll downgrade vm_page_prot 1636 * to the private version (using protection_map[] without the 1637 * VM_SHARED bit). 1638 */ 1639 int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot) 1640 { 1641 vm_flags_t vm_flags = vma->vm_flags; 1642 const struct vm_operations_struct *vm_ops = vma->vm_ops; 1643 1644 /* If it was private or non-writable, the write bit is already clear */ 1645 if ((vm_flags & (VM_WRITE|VM_SHARED)) != ((VM_WRITE|VM_SHARED))) 1646 return 0; 1647 1648 /* The backer wishes to know when pages are first written to? */ 1649 if (vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite)) 1650 return 1; 1651 1652 /* The open routine did something to the protections that pgprot_modify 1653 * won't preserve? */ 1654 if (pgprot_val(vm_page_prot) != 1655 pgprot_val(vm_pgprot_modify(vm_page_prot, vm_flags))) 1656 return 0; 1657 1658 /* Do we need to track softdirty? */ 1659 if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) && !(vm_flags & VM_SOFTDIRTY)) 1660 return 1; 1661 1662 /* Specialty mapping? */ 1663 if (vm_flags & VM_PFNMAP) 1664 return 0; 1665 1666 /* Can the mapping track the dirty pages? */ 1667 return vma->vm_file && vma->vm_file->f_mapping && 1668 mapping_cap_account_dirty(vma->vm_file->f_mapping); 1669 } 1670 1671 /* 1672 * We account for memory if it's a private writeable mapping, 1673 * not hugepages and VM_NORESERVE wasn't set. 1674 */ 1675 static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags) 1676 { 1677 /* 1678 * hugetlb has its own accounting separate from the core VM 1679 * VM_HUGETLB may not be set yet so we cannot check for that flag. 1680 */ 1681 if (file && is_file_hugepages(file)) 1682 return 0; 1683 1684 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE; 1685 } 1686 1687 unsigned long mmap_region(struct file *file, unsigned long addr, 1688 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, 1689 struct list_head *uf) 1690 { 1691 struct mm_struct *mm = current->mm; 1692 struct vm_area_struct *vma, *prev; 1693 int error; 1694 struct rb_node **rb_link, *rb_parent; 1695 unsigned long charged = 0; 1696 1697 /* Check against address space limit. */ 1698 if (!may_expand_vm(mm, vm_flags, len >> PAGE_SHIFT)) { 1699 unsigned long nr_pages; 1700 1701 /* 1702 * MAP_FIXED may remove pages of mappings that intersects with 1703 * requested mapping. Account for the pages it would unmap. 1704 */ 1705 nr_pages = count_vma_pages_range(mm, addr, addr + len); 1706 1707 if (!may_expand_vm(mm, vm_flags, 1708 (len >> PAGE_SHIFT) - nr_pages)) 1709 return -ENOMEM; 1710 } 1711 1712 /* Clear old maps */ 1713 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, 1714 &rb_parent)) { 1715 if (do_munmap(mm, addr, len, uf)) 1716 return -ENOMEM; 1717 } 1718 1719 /* 1720 * Private writable mapping: check memory availability 1721 */ 1722 if (accountable_mapping(file, vm_flags)) { 1723 charged = len >> PAGE_SHIFT; 1724 if (security_vm_enough_memory_mm(mm, charged)) 1725 return -ENOMEM; 1726 vm_flags |= VM_ACCOUNT; 1727 } 1728 1729 /* 1730 * Can we just expand an old mapping? 1731 */ 1732 vma = vma_merge(mm, prev, addr, addr + len, vm_flags, 1733 NULL, file, pgoff, NULL, NULL_VM_UFFD_CTX); 1734 if (vma) 1735 goto out; 1736 1737 /* 1738 * Determine the object being mapped and call the appropriate 1739 * specific mapper. the address has already been validated, but 1740 * not unmapped, but the maps are removed from the list. 1741 */ 1742 vma = vm_area_alloc(mm); 1743 if (!vma) { 1744 error = -ENOMEM; 1745 goto unacct_error; 1746 } 1747 1748 vma->vm_start = addr; 1749 vma->vm_end = addr + len; 1750 vma->vm_flags = vm_flags; 1751 vma->vm_page_prot = vm_get_page_prot(vm_flags); 1752 vma->vm_pgoff = pgoff; 1753 1754 if (file) { 1755 if (vm_flags & VM_DENYWRITE) { 1756 error = deny_write_access(file); 1757 if (error) 1758 goto free_vma; 1759 } 1760 if (vm_flags & VM_SHARED) { 1761 error = mapping_map_writable(file->f_mapping); 1762 if (error) 1763 goto allow_write_and_free_vma; 1764 } 1765 1766 /* ->mmap() can change vma->vm_file, but must guarantee that 1767 * vma_link() below can deny write-access if VM_DENYWRITE is set 1768 * and map writably if VM_SHARED is set. This usually means the 1769 * new file must not have been exposed to user-space, yet. 1770 */ 1771 vma->vm_file = get_file(file); 1772 error = call_mmap(file, vma); 1773 if (error) 1774 goto unmap_and_free_vma; 1775 1776 /* Can addr have changed?? 1777 * 1778 * Answer: Yes, several device drivers can do it in their 1779 * f_op->mmap method. -DaveM 1780 * Bug: If addr is changed, prev, rb_link, rb_parent should 1781 * be updated for vma_link() 1782 */ 1783 WARN_ON_ONCE(addr != vma->vm_start); 1784 1785 addr = vma->vm_start; 1786 vm_flags = vma->vm_flags; 1787 } else if (vm_flags & VM_SHARED) { 1788 error = shmem_zero_setup(vma); 1789 if (error) 1790 goto free_vma; 1791 } else { 1792 vma_set_anonymous(vma); 1793 } 1794 1795 vma_link(mm, vma, prev, rb_link, rb_parent); 1796 /* Once vma denies write, undo our temporary denial count */ 1797 if (file) { 1798 if (vm_flags & VM_SHARED) 1799 mapping_unmap_writable(file->f_mapping); 1800 if (vm_flags & VM_DENYWRITE) 1801 allow_write_access(file); 1802 } 1803 file = vma->vm_file; 1804 out: 1805 perf_event_mmap(vma); 1806 1807 vm_stat_account(mm, vm_flags, len >> PAGE_SHIFT); 1808 if (vm_flags & VM_LOCKED) { 1809 if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) || 1810 is_vm_hugetlb_page(vma) || 1811 vma == get_gate_vma(current->mm)) 1812 vma->vm_flags &= VM_LOCKED_CLEAR_MASK; 1813 else 1814 mm->locked_vm += (len >> PAGE_SHIFT); 1815 } 1816 1817 if (file) 1818 uprobe_mmap(vma); 1819 1820 /* 1821 * New (or expanded) vma always get soft dirty status. 1822 * Otherwise user-space soft-dirty page tracker won't 1823 * be able to distinguish situation when vma area unmapped, 1824 * then new mapped in-place (which must be aimed as 1825 * a completely new data area). 1826 */ 1827 vma->vm_flags |= VM_SOFTDIRTY; 1828 1829 vma_set_page_prot(vma); 1830 1831 return addr; 1832 1833 unmap_and_free_vma: 1834 vma->vm_file = NULL; 1835 fput(file); 1836 1837 /* Undo any partial mapping done by a device driver. */ 1838 unmap_region(mm, vma, prev, vma->vm_start, vma->vm_end); 1839 charged = 0; 1840 if (vm_flags & VM_SHARED) 1841 mapping_unmap_writable(file->f_mapping); 1842 allow_write_and_free_vma: 1843 if (vm_flags & VM_DENYWRITE) 1844 allow_write_access(file); 1845 free_vma: 1846 vm_area_free(vma); 1847 unacct_error: 1848 if (charged) 1849 vm_unacct_memory(charged); 1850 return error; 1851 } 1852 1853 static unsigned long unmapped_area(struct vm_unmapped_area_info *info) 1854 { 1855 /* 1856 * We implement the search by looking for an rbtree node that 1857 * immediately follows a suitable gap. That is, 1858 * - gap_start = vma->vm_prev->vm_end <= info->high_limit - length; 1859 * - gap_end = vma->vm_start >= info->low_limit + length; 1860 * - gap_end - gap_start >= length 1861 */ 1862 1863 struct mm_struct *mm = current->mm; 1864 struct vm_area_struct *vma; 1865 unsigned long length, low_limit, high_limit, gap_start, gap_end; 1866 1867 /* Adjust search length to account for worst case alignment overhead */ 1868 length = info->length + info->align_mask; 1869 if (length < info->length) 1870 return -ENOMEM; 1871 1872 /* Adjust search limits by the desired length */ 1873 if (info->high_limit < length) 1874 return -ENOMEM; 1875 high_limit = info->high_limit - length; 1876 1877 if (info->low_limit > high_limit) 1878 return -ENOMEM; 1879 low_limit = info->low_limit + length; 1880 1881 /* Check if rbtree root looks promising */ 1882 if (RB_EMPTY_ROOT(&mm->mm_rb)) 1883 goto check_highest; 1884 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); 1885 if (vma->rb_subtree_gap < length) 1886 goto check_highest; 1887 1888 while (true) { 1889 /* Visit left subtree if it looks promising */ 1890 gap_end = vm_start_gap(vma); 1891 if (gap_end >= low_limit && vma->vm_rb.rb_left) { 1892 struct vm_area_struct *left = 1893 rb_entry(vma->vm_rb.rb_left, 1894 struct vm_area_struct, vm_rb); 1895 if (left->rb_subtree_gap >= length) { 1896 vma = left; 1897 continue; 1898 } 1899 } 1900 1901 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; 1902 check_current: 1903 /* Check if current node has a suitable gap */ 1904 if (gap_start > high_limit) 1905 return -ENOMEM; 1906 if (gap_end >= low_limit && 1907 gap_end > gap_start && gap_end - gap_start >= length) 1908 goto found; 1909 1910 /* Visit right subtree if it looks promising */ 1911 if (vma->vm_rb.rb_right) { 1912 struct vm_area_struct *right = 1913 rb_entry(vma->vm_rb.rb_right, 1914 struct vm_area_struct, vm_rb); 1915 if (right->rb_subtree_gap >= length) { 1916 vma = right; 1917 continue; 1918 } 1919 } 1920 1921 /* Go back up the rbtree to find next candidate node */ 1922 while (true) { 1923 struct rb_node *prev = &vma->vm_rb; 1924 if (!rb_parent(prev)) 1925 goto check_highest; 1926 vma = rb_entry(rb_parent(prev), 1927 struct vm_area_struct, vm_rb); 1928 if (prev == vma->vm_rb.rb_left) { 1929 gap_start = vm_end_gap(vma->vm_prev); 1930 gap_end = vm_start_gap(vma); 1931 goto check_current; 1932 } 1933 } 1934 } 1935 1936 check_highest: 1937 /* Check highest gap, which does not precede any rbtree node */ 1938 gap_start = mm->highest_vm_end; 1939 gap_end = ULONG_MAX; /* Only for VM_BUG_ON below */ 1940 if (gap_start > high_limit) 1941 return -ENOMEM; 1942 1943 found: 1944 /* We found a suitable gap. Clip it with the original low_limit. */ 1945 if (gap_start < info->low_limit) 1946 gap_start = info->low_limit; 1947 1948 /* Adjust gap address to the desired alignment */ 1949 gap_start += (info->align_offset - gap_start) & info->align_mask; 1950 1951 VM_BUG_ON(gap_start + info->length > info->high_limit); 1952 VM_BUG_ON(gap_start + info->length > gap_end); 1953 return gap_start; 1954 } 1955 1956 static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info) 1957 { 1958 struct mm_struct *mm = current->mm; 1959 struct vm_area_struct *vma; 1960 unsigned long length, low_limit, high_limit, gap_start, gap_end; 1961 1962 /* Adjust search length to account for worst case alignment overhead */ 1963 length = info->length + info->align_mask; 1964 if (length < info->length) 1965 return -ENOMEM; 1966 1967 /* 1968 * Adjust search limits by the desired length. 1969 * See implementation comment at top of unmapped_area(). 1970 */ 1971 gap_end = info->high_limit; 1972 if (gap_end < length) 1973 return -ENOMEM; 1974 high_limit = gap_end - length; 1975 1976 if (info->low_limit > high_limit) 1977 return -ENOMEM; 1978 low_limit = info->low_limit + length; 1979 1980 /* Check highest gap, which does not precede any rbtree node */ 1981 gap_start = mm->highest_vm_end; 1982 if (gap_start <= high_limit) 1983 goto found_highest; 1984 1985 /* Check if rbtree root looks promising */ 1986 if (RB_EMPTY_ROOT(&mm->mm_rb)) 1987 return -ENOMEM; 1988 vma = rb_entry(mm->mm_rb.rb_node, struct vm_area_struct, vm_rb); 1989 if (vma->rb_subtree_gap < length) 1990 return -ENOMEM; 1991 1992 while (true) { 1993 /* Visit right subtree if it looks promising */ 1994 gap_start = vma->vm_prev ? vm_end_gap(vma->vm_prev) : 0; 1995 if (gap_start <= high_limit && vma->vm_rb.rb_right) { 1996 struct vm_area_struct *right = 1997 rb_entry(vma->vm_rb.rb_right, 1998 struct vm_area_struct, vm_rb); 1999 if (right->rb_subtree_gap >= length) { 2000 vma = right; 2001 continue; 2002 } 2003 } 2004 2005 check_current: 2006 /* Check if current node has a suitable gap */ 2007 gap_end = vm_start_gap(vma); 2008 if (gap_end < low_limit) 2009 return -ENOMEM; 2010 if (gap_start <= high_limit && 2011 gap_end > gap_start && gap_end - gap_start >= length) 2012 goto found; 2013 2014 /* Visit left subtree if it looks promising */ 2015 if (vma->vm_rb.rb_left) { 2016 struct vm_area_struct *left = 2017 rb_entry(vma->vm_rb.rb_left, 2018 struct vm_area_struct, vm_rb); 2019 if (left->rb_subtree_gap >= length) { 2020 vma = left; 2021 continue; 2022 } 2023 } 2024 2025 /* Go back up the rbtree to find next candidate node */ 2026 while (true) { 2027 struct rb_node *prev = &vma->vm_rb; 2028 if (!rb_parent(prev)) 2029 return -ENOMEM; 2030 vma = rb_entry(rb_parent(prev), 2031 struct vm_area_struct, vm_rb); 2032 if (prev == vma->vm_rb.rb_right) { 2033 gap_start = vma->vm_prev ? 2034 vm_end_gap(vma->vm_prev) : 0; 2035 goto check_current; 2036 } 2037 } 2038 } 2039 2040 found: 2041 /* We found a suitable gap. Clip it with the original high_limit. */ 2042 if (gap_end > info->high_limit) 2043 gap_end = info->high_limit; 2044 2045 found_highest: 2046 /* Compute highest gap address at the desired alignment */ 2047 gap_end -= info->length; 2048 gap_end -= (gap_end - info->align_offset) & info->align_mask; 2049 2050 VM_BUG_ON(gap_end < info->low_limit); 2051 VM_BUG_ON(gap_end < gap_start); 2052 return gap_end; 2053 } 2054 2055 /* 2056 * Search for an unmapped address range. 2057 * 2058 * We are looking for a range that: 2059 * - does not intersect with any VMA; 2060 * - is contained within the [low_limit, high_limit) interval; 2061 * - is at least the desired size. 2062 * - satisfies (begin_addr & align_mask) == (align_offset & align_mask) 2063 */ 2064 unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info) 2065 { 2066 unsigned long addr; 2067 2068 if (info->flags & VM_UNMAPPED_AREA_TOPDOWN) 2069 addr = unmapped_area_topdown(info); 2070 else 2071 addr = unmapped_area(info); 2072 2073 trace_vm_unmapped_area(addr, info); 2074 return addr; 2075 } 2076 2077 #ifndef arch_get_mmap_end 2078 #define arch_get_mmap_end(addr) (TASK_SIZE) 2079 #endif 2080 2081 #ifndef arch_get_mmap_base 2082 #define arch_get_mmap_base(addr, base) (base) 2083 #endif 2084 2085 /* Get an address range which is currently unmapped. 2086 * For shmat() with addr=0. 2087 * 2088 * Ugly calling convention alert: 2089 * Return value with the low bits set means error value, 2090 * ie 2091 * if (ret & ~PAGE_MASK) 2092 * error = ret; 2093 * 2094 * This function "knows" that -ENOMEM has the bits set. 2095 */ 2096 #ifndef HAVE_ARCH_UNMAPPED_AREA 2097 unsigned long 2098 arch_get_unmapped_area(struct file *filp, unsigned long addr, 2099 unsigned long len, unsigned long pgoff, unsigned long flags) 2100 { 2101 struct mm_struct *mm = current->mm; 2102 struct vm_area_struct *vma, *prev; 2103 struct vm_unmapped_area_info info; 2104 const unsigned long mmap_end = arch_get_mmap_end(addr); 2105 2106 if (len > mmap_end - mmap_min_addr) 2107 return -ENOMEM; 2108 2109 if (flags & MAP_FIXED) 2110 return addr; 2111 2112 if (addr) { 2113 addr = PAGE_ALIGN(addr); 2114 vma = find_vma_prev(mm, addr, &prev); 2115 if (mmap_end - len >= addr && addr >= mmap_min_addr && 2116 (!vma || addr + len <= vm_start_gap(vma)) && 2117 (!prev || addr >= vm_end_gap(prev))) 2118 return addr; 2119 } 2120 2121 info.flags = 0; 2122 info.length = len; 2123 info.low_limit = mm->mmap_base; 2124 info.high_limit = mmap_end; 2125 info.align_mask = 0; 2126 return vm_unmapped_area(&info); 2127 } 2128 #endif 2129 2130 /* 2131 * This mmap-allocator allocates new areas top-down from below the 2132 * stack's low limit (the base): 2133 */ 2134 #ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN 2135 unsigned long 2136 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr, 2137 unsigned long len, unsigned long pgoff, 2138 unsigned long flags) 2139 { 2140 struct vm_area_struct *vma, *prev; 2141 struct mm_struct *mm = current->mm; 2142 struct vm_unmapped_area_info info; 2143 const unsigned long mmap_end = arch_get_mmap_end(addr); 2144 2145 /* requested length too big for entire address space */ 2146 if (len > mmap_end - mmap_min_addr) 2147 return -ENOMEM; 2148 2149 if (flags & MAP_FIXED) 2150 return addr; 2151 2152 /* requesting a specific address */ 2153 if (addr) { 2154 addr = PAGE_ALIGN(addr); 2155 vma = find_vma_prev(mm, addr, &prev); 2156 if (mmap_end - len >= addr && addr >= mmap_min_addr && 2157 (!vma || addr + len <= vm_start_gap(vma)) && 2158 (!prev || addr >= vm_end_gap(prev))) 2159 return addr; 2160 } 2161 2162 info.flags = VM_UNMAPPED_AREA_TOPDOWN; 2163 info.length = len; 2164 info.low_limit = max(PAGE_SIZE, mmap_min_addr); 2165 info.high_limit = arch_get_mmap_base(addr, mm->mmap_base); 2166 info.align_mask = 0; 2167 addr = vm_unmapped_area(&info); 2168 2169 /* 2170 * A failed mmap() very likely causes application failure, 2171 * so fall back to the bottom-up function here. This scenario 2172 * can happen with large stack limits and large mmap() 2173 * allocations. 2174 */ 2175 if (offset_in_page(addr)) { 2176 VM_BUG_ON(addr != -ENOMEM); 2177 info.flags = 0; 2178 info.low_limit = TASK_UNMAPPED_BASE; 2179 info.high_limit = mmap_end; 2180 addr = vm_unmapped_area(&info); 2181 } 2182 2183 return addr; 2184 } 2185 #endif 2186 2187 unsigned long 2188 get_unmapped_area(struct file *file, unsigned long addr, unsigned long len, 2189 unsigned long pgoff, unsigned long flags) 2190 { 2191 unsigned long (*get_area)(struct file *, unsigned long, 2192 unsigned long, unsigned long, unsigned long); 2193 2194 unsigned long error = arch_mmap_check(addr, len, flags); 2195 if (error) 2196 return error; 2197 2198 /* Careful about overflows.. */ 2199 if (len > TASK_SIZE) 2200 return -ENOMEM; 2201 2202 get_area = current->mm->get_unmapped_area; 2203 if (file) { 2204 if (file->f_op->get_unmapped_area) 2205 get_area = file->f_op->get_unmapped_area; 2206 } else if (flags & MAP_SHARED) { 2207 /* 2208 * mmap_region() will call shmem_zero_setup() to create a file, 2209 * so use shmem's get_unmapped_area in case it can be huge. 2210 * do_mmap_pgoff() will clear pgoff, so match alignment. 2211 */ 2212 pgoff = 0; 2213 get_area = shmem_get_unmapped_area; 2214 } 2215 2216 addr = get_area(file, addr, len, pgoff, flags); 2217 if (IS_ERR_VALUE(addr)) 2218 return addr; 2219 2220 if (addr > TASK_SIZE - len) 2221 return -ENOMEM; 2222 if (offset_in_page(addr)) 2223 return -EINVAL; 2224 2225 error = security_mmap_addr(addr); 2226 return error ? error : addr; 2227 } 2228 2229 EXPORT_SYMBOL(get_unmapped_area); 2230 2231 /* Look up the first VMA which satisfies addr < vm_end, NULL if none. */ 2232 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 2233 { 2234 struct rb_node *rb_node; 2235 struct vm_area_struct *vma; 2236 2237 /* Check the cache first. */ 2238 vma = vmacache_find(mm, addr); 2239 if (likely(vma)) 2240 return vma; 2241 2242 rb_node = mm->mm_rb.rb_node; 2243 2244 while (rb_node) { 2245 struct vm_area_struct *tmp; 2246 2247 tmp = rb_entry(rb_node, struct vm_area_struct, vm_rb); 2248 2249 if (tmp->vm_end > addr) { 2250 vma = tmp; 2251 if (tmp->vm_start <= addr) 2252 break; 2253 rb_node = rb_node->rb_left; 2254 } else 2255 rb_node = rb_node->rb_right; 2256 } 2257 2258 if (vma) 2259 vmacache_update(addr, vma); 2260 return vma; 2261 } 2262 2263 EXPORT_SYMBOL(find_vma); 2264 2265 /* 2266 * Same as find_vma, but also return a pointer to the previous VMA in *pprev. 2267 */ 2268 struct vm_area_struct * 2269 find_vma_prev(struct mm_struct *mm, unsigned long addr, 2270 struct vm_area_struct **pprev) 2271 { 2272 struct vm_area_struct *vma; 2273 2274 vma = find_vma(mm, addr); 2275 if (vma) { 2276 *pprev = vma->vm_prev; 2277 } else { 2278 struct rb_node *rb_node = rb_last(&mm->mm_rb); 2279 2280 *pprev = rb_node ? rb_entry(rb_node, struct vm_area_struct, vm_rb) : NULL; 2281 } 2282 return vma; 2283 } 2284 2285 /* 2286 * Verify that the stack growth is acceptable and 2287 * update accounting. This is shared with both the 2288 * grow-up and grow-down cases. 2289 */ 2290 static int acct_stack_growth(struct vm_area_struct *vma, 2291 unsigned long size, unsigned long grow) 2292 { 2293 struct mm_struct *mm = vma->vm_mm; 2294 unsigned long new_start; 2295 2296 /* address space limit tests */ 2297 if (!may_expand_vm(mm, vma->vm_flags, grow)) 2298 return -ENOMEM; 2299 2300 /* Stack limit test */ 2301 if (size > rlimit(RLIMIT_STACK)) 2302 return -ENOMEM; 2303 2304 /* mlock limit tests */ 2305 if (vma->vm_flags & VM_LOCKED) { 2306 unsigned long locked; 2307 unsigned long limit; 2308 locked = mm->locked_vm + grow; 2309 limit = rlimit(RLIMIT_MEMLOCK); 2310 limit >>= PAGE_SHIFT; 2311 if (locked > limit && !capable(CAP_IPC_LOCK)) 2312 return -ENOMEM; 2313 } 2314 2315 /* Check to ensure the stack will not grow into a hugetlb-only region */ 2316 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start : 2317 vma->vm_end - size; 2318 if (is_hugepage_only_range(vma->vm_mm, new_start, size)) 2319 return -EFAULT; 2320 2321 /* 2322 * Overcommit.. This must be the final test, as it will 2323 * update security statistics. 2324 */ 2325 if (security_vm_enough_memory_mm(mm, grow)) 2326 return -ENOMEM; 2327 2328 return 0; 2329 } 2330 2331 #if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64) 2332 /* 2333 * PA-RISC uses this for its stack; IA64 for its Register Backing Store. 2334 * vma is the last one with address > vma->vm_end. Have to extend vma. 2335 */ 2336 int expand_upwards(struct vm_area_struct *vma, unsigned long address) 2337 { 2338 struct mm_struct *mm = vma->vm_mm; 2339 struct vm_area_struct *next; 2340 unsigned long gap_addr; 2341 int error = 0; 2342 2343 if (!(vma->vm_flags & VM_GROWSUP)) 2344 return -EFAULT; 2345 2346 /* Guard against exceeding limits of the address space. */ 2347 address &= PAGE_MASK; 2348 if (address >= (TASK_SIZE & PAGE_MASK)) 2349 return -ENOMEM; 2350 address += PAGE_SIZE; 2351 2352 /* Enforce stack_guard_gap */ 2353 gap_addr = address + stack_guard_gap; 2354 2355 /* Guard against overflow */ 2356 if (gap_addr < address || gap_addr > TASK_SIZE) 2357 gap_addr = TASK_SIZE; 2358 2359 next = vma->vm_next; 2360 if (next && next->vm_start < gap_addr && vma_is_accessible(next)) { 2361 if (!(next->vm_flags & VM_GROWSUP)) 2362 return -ENOMEM; 2363 /* Check that both stack segments have the same anon_vma? */ 2364 } 2365 2366 /* We must make sure the anon_vma is allocated. */ 2367 if (unlikely(anon_vma_prepare(vma))) 2368 return -ENOMEM; 2369 2370 /* 2371 * vma->vm_start/vm_end cannot change under us because the caller 2372 * is required to hold the mmap_sem in read mode. We need the 2373 * anon_vma lock to serialize against concurrent expand_stacks. 2374 */ 2375 anon_vma_lock_write(vma->anon_vma); 2376 2377 /* Somebody else might have raced and expanded it already */ 2378 if (address > vma->vm_end) { 2379 unsigned long size, grow; 2380 2381 size = address - vma->vm_start; 2382 grow = (address - vma->vm_end) >> PAGE_SHIFT; 2383 2384 error = -ENOMEM; 2385 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) { 2386 error = acct_stack_growth(vma, size, grow); 2387 if (!error) { 2388 /* 2389 * vma_gap_update() doesn't support concurrent 2390 * updates, but we only hold a shared mmap_sem 2391 * lock here, so we need to protect against 2392 * concurrent vma expansions. 2393 * anon_vma_lock_write() doesn't help here, as 2394 * we don't guarantee that all growable vmas 2395 * in a mm share the same root anon vma. 2396 * So, we reuse mm->page_table_lock to guard 2397 * against concurrent vma expansions. 2398 */ 2399 spin_lock(&mm->page_table_lock); 2400 if (vma->vm_flags & VM_LOCKED) 2401 mm->locked_vm += grow; 2402 vm_stat_account(mm, vma->vm_flags, grow); 2403 anon_vma_interval_tree_pre_update_vma(vma); 2404 vma->vm_end = address; 2405 anon_vma_interval_tree_post_update_vma(vma); 2406 if (vma->vm_next) 2407 vma_gap_update(vma->vm_next); 2408 else 2409 mm->highest_vm_end = vm_end_gap(vma); 2410 spin_unlock(&mm->page_table_lock); 2411 2412 perf_event_mmap(vma); 2413 } 2414 } 2415 } 2416 anon_vma_unlock_write(vma->anon_vma); 2417 khugepaged_enter_vma_merge(vma, vma->vm_flags); 2418 validate_mm(mm); 2419 return error; 2420 } 2421 #endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */ 2422 2423 /* 2424 * vma is the first one with address < vma->vm_start. Have to extend vma. 2425 */ 2426 int expand_downwards(struct vm_area_struct *vma, 2427 unsigned long address) 2428 { 2429 struct mm_struct *mm = vma->vm_mm; 2430 struct vm_area_struct *prev; 2431 int error = 0; 2432 2433 address &= PAGE_MASK; 2434 if (address < mmap_min_addr) 2435 return -EPERM; 2436 2437 /* Enforce stack_guard_gap */ 2438 prev = vma->vm_prev; 2439 /* Check that both stack segments have the same anon_vma? */ 2440 if (prev && !(prev->vm_flags & VM_GROWSDOWN) && 2441 vma_is_accessible(prev)) { 2442 if (address - prev->vm_end < stack_guard_gap) 2443 return -ENOMEM; 2444 } 2445 2446 /* We must make sure the anon_vma is allocated. */ 2447 if (unlikely(anon_vma_prepare(vma))) 2448 return -ENOMEM; 2449 2450 /* 2451 * vma->vm_start/vm_end cannot change under us because the caller 2452 * is required to hold the mmap_sem in read mode. We need the 2453 * anon_vma lock to serialize against concurrent expand_stacks. 2454 */ 2455 anon_vma_lock_write(vma->anon_vma); 2456 2457 /* Somebody else might have raced and expanded it already */ 2458 if (address < vma->vm_start) { 2459 unsigned long size, grow; 2460 2461 size = vma->vm_end - address; 2462 grow = (vma->vm_start - address) >> PAGE_SHIFT; 2463 2464 error = -ENOMEM; 2465 if (grow <= vma->vm_pgoff) { 2466 error = acct_stack_growth(vma, size, grow); 2467 if (!error) { 2468 /* 2469 * vma_gap_update() doesn't support concurrent 2470 * updates, but we only hold a shared mmap_sem 2471 * lock here, so we need to protect against 2472 * concurrent vma expansions. 2473 * anon_vma_lock_write() doesn't help here, as 2474 * we don't guarantee that all growable vmas 2475 * in a mm share the same root anon vma. 2476 * So, we reuse mm->page_table_lock to guard 2477 * against concurrent vma expansions. 2478 */ 2479 spin_lock(&mm->page_table_lock); 2480 if (vma->vm_flags & VM_LOCKED) 2481 mm->locked_vm += grow; 2482 vm_stat_account(mm, vma->vm_flags, grow); 2483 anon_vma_interval_tree_pre_update_vma(vma); 2484 vma->vm_start = address; 2485 vma->vm_pgoff -= grow; 2486 anon_vma_interval_tree_post_update_vma(vma); 2487 vma_gap_update(vma); 2488 spin_unlock(&mm->page_table_lock); 2489 2490 perf_event_mmap(vma); 2491 } 2492 } 2493 } 2494 anon_vma_unlock_write(vma->anon_vma); 2495 khugepaged_enter_vma_merge(vma, vma->vm_flags); 2496 validate_mm(mm); 2497 return error; 2498 } 2499 2500 /* enforced gap between the expanding stack and other mappings. */ 2501 unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT; 2502 2503 static int __init cmdline_parse_stack_guard_gap(char *p) 2504 { 2505 unsigned long val; 2506 char *endptr; 2507 2508 val = simple_strtoul(p, &endptr, 10); 2509 if (!*endptr) 2510 stack_guard_gap = val << PAGE_SHIFT; 2511 2512 return 0; 2513 } 2514 __setup("stack_guard_gap=", cmdline_parse_stack_guard_gap); 2515 2516 #ifdef CONFIG_STACK_GROWSUP 2517 int expand_stack(struct vm_area_struct *vma, unsigned long address) 2518 { 2519 return expand_upwards(vma, address); 2520 } 2521 2522 struct vm_area_struct * 2523 find_extend_vma(struct mm_struct *mm, unsigned long addr) 2524 { 2525 struct vm_area_struct *vma, *prev; 2526 2527 addr &= PAGE_MASK; 2528 vma = find_vma_prev(mm, addr, &prev); 2529 if (vma && (vma->vm_start <= addr)) 2530 return vma; 2531 /* don't alter vm_end if the coredump is running */ 2532 if (!prev || !mmget_still_valid(mm) || expand_stack(prev, addr)) 2533 return NULL; 2534 if (prev->vm_flags & VM_LOCKED) 2535 populate_vma_page_range(prev, addr, prev->vm_end, NULL); 2536 return prev; 2537 } 2538 #else 2539 int expand_stack(struct vm_area_struct *vma, unsigned long address) 2540 { 2541 return expand_downwards(vma, address); 2542 } 2543 2544 struct vm_area_struct * 2545 find_extend_vma(struct mm_struct *mm, unsigned long addr) 2546 { 2547 struct vm_area_struct *vma; 2548 unsigned long start; 2549 2550 addr &= PAGE_MASK; 2551 vma = find_vma(mm, addr); 2552 if (!vma) 2553 return NULL; 2554 if (vma->vm_start <= addr) 2555 return vma; 2556 if (!(vma->vm_flags & VM_GROWSDOWN)) 2557 return NULL; 2558 /* don't alter vm_start if the coredump is running */ 2559 if (!mmget_still_valid(mm)) 2560 return NULL; 2561 start = vma->vm_start; 2562 if (expand_stack(vma, addr)) 2563 return NULL; 2564 if (vma->vm_flags & VM_LOCKED) 2565 populate_vma_page_range(vma, addr, start, NULL); 2566 return vma; 2567 } 2568 #endif 2569 2570 EXPORT_SYMBOL_GPL(find_extend_vma); 2571 2572 /* 2573 * Ok - we have the memory areas we should free on the vma list, 2574 * so release them, and do the vma updates. 2575 * 2576 * Called with the mm semaphore held. 2577 */ 2578 static void remove_vma_list(struct mm_struct *mm, struct vm_area_struct *vma) 2579 { 2580 unsigned long nr_accounted = 0; 2581 2582 /* Update high watermark before we lower total_vm */ 2583 update_hiwater_vm(mm); 2584 do { 2585 long nrpages = vma_pages(vma); 2586 2587 if (vma->vm_flags & VM_ACCOUNT) 2588 nr_accounted += nrpages; 2589 vm_stat_account(mm, vma->vm_flags, -nrpages); 2590 vma = remove_vma(vma); 2591 } while (vma); 2592 vm_unacct_memory(nr_accounted); 2593 validate_mm(mm); 2594 } 2595 2596 /* 2597 * Get rid of page table information in the indicated region. 2598 * 2599 * Called with the mm semaphore held. 2600 */ 2601 static void unmap_region(struct mm_struct *mm, 2602 struct vm_area_struct *vma, struct vm_area_struct *prev, 2603 unsigned long start, unsigned long end) 2604 { 2605 struct vm_area_struct *next = prev ? prev->vm_next : mm->mmap; 2606 struct mmu_gather tlb; 2607 2608 lru_add_drain(); 2609 tlb_gather_mmu(&tlb, mm, start, end); 2610 update_hiwater_rss(mm); 2611 unmap_vmas(&tlb, vma, start, end); 2612 free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS, 2613 next ? next->vm_start : USER_PGTABLES_CEILING); 2614 tlb_finish_mmu(&tlb, start, end); 2615 } 2616 2617 /* 2618 * Create a list of vma's touched by the unmap, removing them from the mm's 2619 * vma list as we go.. 2620 */ 2621 static void 2622 detach_vmas_to_be_unmapped(struct mm_struct *mm, struct vm_area_struct *vma, 2623 struct vm_area_struct *prev, unsigned long end) 2624 { 2625 struct vm_area_struct **insertion_point; 2626 struct vm_area_struct *tail_vma = NULL; 2627 2628 insertion_point = (prev ? &prev->vm_next : &mm->mmap); 2629 vma->vm_prev = NULL; 2630 do { 2631 vma_rb_erase(vma, &mm->mm_rb); 2632 mm->map_count--; 2633 tail_vma = vma; 2634 vma = vma->vm_next; 2635 } while (vma && vma->vm_start < end); 2636 *insertion_point = vma; 2637 if (vma) { 2638 vma->vm_prev = prev; 2639 vma_gap_update(vma); 2640 } else 2641 mm->highest_vm_end = prev ? vm_end_gap(prev) : 0; 2642 tail_vma->vm_next = NULL; 2643 2644 /* Kill the cache */ 2645 vmacache_invalidate(mm); 2646 } 2647 2648 /* 2649 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it 2650 * has already been checked or doesn't make sense to fail. 2651 */ 2652 int __split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 2653 unsigned long addr, int new_below) 2654 { 2655 struct vm_area_struct *new; 2656 int err; 2657 2658 if (vma->vm_ops && vma->vm_ops->split) { 2659 err = vma->vm_ops->split(vma, addr); 2660 if (err) 2661 return err; 2662 } 2663 2664 new = vm_area_dup(vma); 2665 if (!new) 2666 return -ENOMEM; 2667 2668 if (new_below) 2669 new->vm_end = addr; 2670 else { 2671 new->vm_start = addr; 2672 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT); 2673 } 2674 2675 err = vma_dup_policy(vma, new); 2676 if (err) 2677 goto out_free_vma; 2678 2679 err = anon_vma_clone(new, vma); 2680 if (err) 2681 goto out_free_mpol; 2682 2683 if (new->vm_file) 2684 get_file(new->vm_file); 2685 2686 if (new->vm_ops && new->vm_ops->open) 2687 new->vm_ops->open(new); 2688 2689 if (new_below) 2690 err = vma_adjust(vma, addr, vma->vm_end, vma->vm_pgoff + 2691 ((addr - new->vm_start) >> PAGE_SHIFT), new); 2692 else 2693 err = vma_adjust(vma, vma->vm_start, addr, vma->vm_pgoff, new); 2694 2695 /* Success. */ 2696 if (!err) 2697 return 0; 2698 2699 /* Clean everything up if vma_adjust failed. */ 2700 if (new->vm_ops && new->vm_ops->close) 2701 new->vm_ops->close(new); 2702 if (new->vm_file) 2703 fput(new->vm_file); 2704 unlink_anon_vmas(new); 2705 out_free_mpol: 2706 mpol_put(vma_policy(new)); 2707 out_free_vma: 2708 vm_area_free(new); 2709 return err; 2710 } 2711 2712 /* 2713 * Split a vma into two pieces at address 'addr', a new vma is allocated 2714 * either for the first part or the tail. 2715 */ 2716 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 2717 unsigned long addr, int new_below) 2718 { 2719 if (mm->map_count >= sysctl_max_map_count) 2720 return -ENOMEM; 2721 2722 return __split_vma(mm, vma, addr, new_below); 2723 } 2724 2725 /* Munmap is split into 2 main parts -- this part which finds 2726 * what needs doing, and the areas themselves, which do the 2727 * work. This now handles partial unmappings. 2728 * Jeremy Fitzhardinge <jeremy@goop.org> 2729 */ 2730 int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len, 2731 struct list_head *uf, bool downgrade) 2732 { 2733 unsigned long end; 2734 struct vm_area_struct *vma, *prev, *last; 2735 2736 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start) 2737 return -EINVAL; 2738 2739 len = PAGE_ALIGN(len); 2740 end = start + len; 2741 if (len == 0) 2742 return -EINVAL; 2743 2744 /* 2745 * arch_unmap() might do unmaps itself. It must be called 2746 * and finish any rbtree manipulation before this code 2747 * runs and also starts to manipulate the rbtree. 2748 */ 2749 arch_unmap(mm, start, end); 2750 2751 /* Find the first overlapping VMA */ 2752 vma = find_vma(mm, start); 2753 if (!vma) 2754 return 0; 2755 prev = vma->vm_prev; 2756 /* we have start < vma->vm_end */ 2757 2758 /* if it doesn't overlap, we have nothing.. */ 2759 if (vma->vm_start >= end) 2760 return 0; 2761 2762 /* 2763 * If we need to split any vma, do it now to save pain later. 2764 * 2765 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially 2766 * unmapped vm_area_struct will remain in use: so lower split_vma 2767 * places tmp vma above, and higher split_vma places tmp vma below. 2768 */ 2769 if (start > vma->vm_start) { 2770 int error; 2771 2772 /* 2773 * Make sure that map_count on return from munmap() will 2774 * not exceed its limit; but let map_count go just above 2775 * its limit temporarily, to help free resources as expected. 2776 */ 2777 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count) 2778 return -ENOMEM; 2779 2780 error = __split_vma(mm, vma, start, 0); 2781 if (error) 2782 return error; 2783 prev = vma; 2784 } 2785 2786 /* Does it split the last one? */ 2787 last = find_vma(mm, end); 2788 if (last && end > last->vm_start) { 2789 int error = __split_vma(mm, last, end, 1); 2790 if (error) 2791 return error; 2792 } 2793 vma = prev ? prev->vm_next : mm->mmap; 2794 2795 if (unlikely(uf)) { 2796 /* 2797 * If userfaultfd_unmap_prep returns an error the vmas 2798 * will remain splitted, but userland will get a 2799 * highly unexpected error anyway. This is no 2800 * different than the case where the first of the two 2801 * __split_vma fails, but we don't undo the first 2802 * split, despite we could. This is unlikely enough 2803 * failure that it's not worth optimizing it for. 2804 */ 2805 int error = userfaultfd_unmap_prep(vma, start, end, uf); 2806 if (error) 2807 return error; 2808 } 2809 2810 /* 2811 * unlock any mlock()ed ranges before detaching vmas 2812 */ 2813 if (mm->locked_vm) { 2814 struct vm_area_struct *tmp = vma; 2815 while (tmp && tmp->vm_start < end) { 2816 if (tmp->vm_flags & VM_LOCKED) { 2817 mm->locked_vm -= vma_pages(tmp); 2818 munlock_vma_pages_all(tmp); 2819 } 2820 2821 tmp = tmp->vm_next; 2822 } 2823 } 2824 2825 /* Detach vmas from rbtree */ 2826 detach_vmas_to_be_unmapped(mm, vma, prev, end); 2827 2828 if (downgrade) 2829 downgrade_write(&mm->mmap_sem); 2830 2831 unmap_region(mm, vma, prev, start, end); 2832 2833 /* Fix up all other VM information */ 2834 remove_vma_list(mm, vma); 2835 2836 return downgrade ? 1 : 0; 2837 } 2838 2839 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, 2840 struct list_head *uf) 2841 { 2842 return __do_munmap(mm, start, len, uf, false); 2843 } 2844 2845 static int __vm_munmap(unsigned long start, size_t len, bool downgrade) 2846 { 2847 int ret; 2848 struct mm_struct *mm = current->mm; 2849 LIST_HEAD(uf); 2850 2851 if (down_write_killable(&mm->mmap_sem)) 2852 return -EINTR; 2853 2854 ret = __do_munmap(mm, start, len, &uf, downgrade); 2855 /* 2856 * Returning 1 indicates mmap_sem is downgraded. 2857 * But 1 is not legal return value of vm_munmap() and munmap(), reset 2858 * it to 0 before return. 2859 */ 2860 if (ret == 1) { 2861 up_read(&mm->mmap_sem); 2862 ret = 0; 2863 } else 2864 up_write(&mm->mmap_sem); 2865 2866 userfaultfd_unmap_complete(mm, &uf); 2867 return ret; 2868 } 2869 2870 int vm_munmap(unsigned long start, size_t len) 2871 { 2872 return __vm_munmap(start, len, false); 2873 } 2874 EXPORT_SYMBOL(vm_munmap); 2875 2876 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 2877 { 2878 addr = untagged_addr(addr); 2879 profile_munmap(addr); 2880 return __vm_munmap(addr, len, true); 2881 } 2882 2883 2884 /* 2885 * Emulation of deprecated remap_file_pages() syscall. 2886 */ 2887 SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size, 2888 unsigned long, prot, unsigned long, pgoff, unsigned long, flags) 2889 { 2890 2891 struct mm_struct *mm = current->mm; 2892 struct vm_area_struct *vma; 2893 unsigned long populate = 0; 2894 unsigned long ret = -EINVAL; 2895 struct file *file; 2896 2897 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n", 2898 current->comm, current->pid); 2899 2900 if (prot) 2901 return ret; 2902 start = start & PAGE_MASK; 2903 size = size & PAGE_MASK; 2904 2905 if (start + size <= start) 2906 return ret; 2907 2908 /* Does pgoff wrap? */ 2909 if (pgoff + (size >> PAGE_SHIFT) < pgoff) 2910 return ret; 2911 2912 if (down_write_killable(&mm->mmap_sem)) 2913 return -EINTR; 2914 2915 vma = find_vma(mm, start); 2916 2917 if (!vma || !(vma->vm_flags & VM_SHARED)) 2918 goto out; 2919 2920 if (start < vma->vm_start) 2921 goto out; 2922 2923 if (start + size > vma->vm_end) { 2924 struct vm_area_struct *next; 2925 2926 for (next = vma->vm_next; next; next = next->vm_next) { 2927 /* hole between vmas ? */ 2928 if (next->vm_start != next->vm_prev->vm_end) 2929 goto out; 2930 2931 if (next->vm_file != vma->vm_file) 2932 goto out; 2933 2934 if (next->vm_flags != vma->vm_flags) 2935 goto out; 2936 2937 if (start + size <= next->vm_end) 2938 break; 2939 } 2940 2941 if (!next) 2942 goto out; 2943 } 2944 2945 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0; 2946 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0; 2947 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0; 2948 2949 flags &= MAP_NONBLOCK; 2950 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE; 2951 if (vma->vm_flags & VM_LOCKED) { 2952 struct vm_area_struct *tmp; 2953 flags |= MAP_LOCKED; 2954 2955 /* drop PG_Mlocked flag for over-mapped range */ 2956 for (tmp = vma; tmp->vm_start >= start + size; 2957 tmp = tmp->vm_next) { 2958 /* 2959 * Split pmd and munlock page on the border 2960 * of the range. 2961 */ 2962 vma_adjust_trans_huge(tmp, start, start + size, 0); 2963 2964 munlock_vma_pages_range(tmp, 2965 max(tmp->vm_start, start), 2966 min(tmp->vm_end, start + size)); 2967 } 2968 } 2969 2970 file = get_file(vma->vm_file); 2971 ret = do_mmap_pgoff(vma->vm_file, start, size, 2972 prot, flags, pgoff, &populate, NULL); 2973 fput(file); 2974 out: 2975 up_write(&mm->mmap_sem); 2976 if (populate) 2977 mm_populate(ret, populate); 2978 if (!IS_ERR_VALUE(ret)) 2979 ret = 0; 2980 return ret; 2981 } 2982 2983 /* 2984 * this is really a simplified "do_mmap". it only handles 2985 * anonymous maps. eventually we may be able to do some 2986 * brk-specific accounting here. 2987 */ 2988 static int do_brk_flags(unsigned long addr, unsigned long len, unsigned long flags, struct list_head *uf) 2989 { 2990 struct mm_struct *mm = current->mm; 2991 struct vm_area_struct *vma, *prev; 2992 struct rb_node **rb_link, *rb_parent; 2993 pgoff_t pgoff = addr >> PAGE_SHIFT; 2994 int error; 2995 unsigned long mapped_addr; 2996 2997 /* Until we need other flags, refuse anything except VM_EXEC. */ 2998 if ((flags & (~VM_EXEC)) != 0) 2999 return -EINVAL; 3000 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags; 3001 3002 mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED); 3003 if (IS_ERR_VALUE(mapped_addr)) 3004 return mapped_addr; 3005 3006 error = mlock_future_check(mm, mm->def_flags, len); 3007 if (error) 3008 return error; 3009 3010 /* 3011 * Clear old maps. this also does some error checking for us 3012 */ 3013 while (find_vma_links(mm, addr, addr + len, &prev, &rb_link, 3014 &rb_parent)) { 3015 if (do_munmap(mm, addr, len, uf)) 3016 return -ENOMEM; 3017 } 3018 3019 /* Check against address space limits *after* clearing old maps... */ 3020 if (!may_expand_vm(mm, flags, len >> PAGE_SHIFT)) 3021 return -ENOMEM; 3022 3023 if (mm->map_count > sysctl_max_map_count) 3024 return -ENOMEM; 3025 3026 if (security_vm_enough_memory_mm(mm, len >> PAGE_SHIFT)) 3027 return -ENOMEM; 3028 3029 /* Can we just expand an old private anonymous mapping? */ 3030 vma = vma_merge(mm, prev, addr, addr + len, flags, 3031 NULL, NULL, pgoff, NULL, NULL_VM_UFFD_CTX); 3032 if (vma) 3033 goto out; 3034 3035 /* 3036 * create a vma struct for an anonymous mapping 3037 */ 3038 vma = vm_area_alloc(mm); 3039 if (!vma) { 3040 vm_unacct_memory(len >> PAGE_SHIFT); 3041 return -ENOMEM; 3042 } 3043 3044 vma_set_anonymous(vma); 3045 vma->vm_start = addr; 3046 vma->vm_end = addr + len; 3047 vma->vm_pgoff = pgoff; 3048 vma->vm_flags = flags; 3049 vma->vm_page_prot = vm_get_page_prot(flags); 3050 vma_link(mm, vma, prev, rb_link, rb_parent); 3051 out: 3052 perf_event_mmap(vma); 3053 mm->total_vm += len >> PAGE_SHIFT; 3054 mm->data_vm += len >> PAGE_SHIFT; 3055 if (flags & VM_LOCKED) 3056 mm->locked_vm += (len >> PAGE_SHIFT); 3057 vma->vm_flags |= VM_SOFTDIRTY; 3058 return 0; 3059 } 3060 3061 int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) 3062 { 3063 struct mm_struct *mm = current->mm; 3064 unsigned long len; 3065 int ret; 3066 bool populate; 3067 LIST_HEAD(uf); 3068 3069 len = PAGE_ALIGN(request); 3070 if (len < request) 3071 return -ENOMEM; 3072 if (!len) 3073 return 0; 3074 3075 if (down_write_killable(&mm->mmap_sem)) 3076 return -EINTR; 3077 3078 ret = do_brk_flags(addr, len, flags, &uf); 3079 populate = ((mm->def_flags & VM_LOCKED) != 0); 3080 up_write(&mm->mmap_sem); 3081 userfaultfd_unmap_complete(mm, &uf); 3082 if (populate && !ret) 3083 mm_populate(addr, len); 3084 return ret; 3085 } 3086 EXPORT_SYMBOL(vm_brk_flags); 3087 3088 int vm_brk(unsigned long addr, unsigned long len) 3089 { 3090 return vm_brk_flags(addr, len, 0); 3091 } 3092 EXPORT_SYMBOL(vm_brk); 3093 3094 /* Release all mmaps. */ 3095 void exit_mmap(struct mm_struct *mm) 3096 { 3097 struct mmu_gather tlb; 3098 struct vm_area_struct *vma; 3099 unsigned long nr_accounted = 0; 3100 3101 /* mm's last user has gone, and its about to be pulled down */ 3102 mmu_notifier_release(mm); 3103 3104 if (unlikely(mm_is_oom_victim(mm))) { 3105 /* 3106 * Manually reap the mm to free as much memory as possible. 3107 * Then, as the oom reaper does, set MMF_OOM_SKIP to disregard 3108 * this mm from further consideration. Taking mm->mmap_sem for 3109 * write after setting MMF_OOM_SKIP will guarantee that the oom 3110 * reaper will not run on this mm again after mmap_sem is 3111 * dropped. 3112 * 3113 * Nothing can be holding mm->mmap_sem here and the above call 3114 * to mmu_notifier_release(mm) ensures mmu notifier callbacks in 3115 * __oom_reap_task_mm() will not block. 3116 * 3117 * This needs to be done before calling munlock_vma_pages_all(), 3118 * which clears VM_LOCKED, otherwise the oom reaper cannot 3119 * reliably test it. 3120 */ 3121 (void)__oom_reap_task_mm(mm); 3122 3123 set_bit(MMF_OOM_SKIP, &mm->flags); 3124 down_write(&mm->mmap_sem); 3125 up_write(&mm->mmap_sem); 3126 } 3127 3128 if (mm->locked_vm) { 3129 vma = mm->mmap; 3130 while (vma) { 3131 if (vma->vm_flags & VM_LOCKED) 3132 munlock_vma_pages_all(vma); 3133 vma = vma->vm_next; 3134 } 3135 } 3136 3137 arch_exit_mmap(mm); 3138 3139 vma = mm->mmap; 3140 if (!vma) /* Can happen if dup_mmap() received an OOM */ 3141 return; 3142 3143 lru_add_drain(); 3144 flush_cache_mm(mm); 3145 tlb_gather_mmu(&tlb, mm, 0, -1); 3146 /* update_hiwater_rss(mm) here? but nobody should be looking */ 3147 /* Use -1 here to ensure all VMAs in the mm are unmapped */ 3148 unmap_vmas(&tlb, vma, 0, -1); 3149 free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, USER_PGTABLES_CEILING); 3150 tlb_finish_mmu(&tlb, 0, -1); 3151 3152 /* 3153 * Walk the list again, actually closing and freeing it, 3154 * with preemption enabled, without holding any MM locks. 3155 */ 3156 while (vma) { 3157 if (vma->vm_flags & VM_ACCOUNT) 3158 nr_accounted += vma_pages(vma); 3159 vma = remove_vma(vma); 3160 } 3161 vm_unacct_memory(nr_accounted); 3162 } 3163 3164 /* Insert vm structure into process list sorted by address 3165 * and into the inode's i_mmap tree. If vm_file is non-NULL 3166 * then i_mmap_rwsem is taken here. 3167 */ 3168 int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma) 3169 { 3170 struct vm_area_struct *prev; 3171 struct rb_node **rb_link, *rb_parent; 3172 3173 if (find_vma_links(mm, vma->vm_start, vma->vm_end, 3174 &prev, &rb_link, &rb_parent)) 3175 return -ENOMEM; 3176 if ((vma->vm_flags & VM_ACCOUNT) && 3177 security_vm_enough_memory_mm(mm, vma_pages(vma))) 3178 return -ENOMEM; 3179 3180 /* 3181 * The vm_pgoff of a purely anonymous vma should be irrelevant 3182 * until its first write fault, when page's anon_vma and index 3183 * are set. But now set the vm_pgoff it will almost certainly 3184 * end up with (unless mremap moves it elsewhere before that 3185 * first wfault), so /proc/pid/maps tells a consistent story. 3186 * 3187 * By setting it to reflect the virtual start address of the 3188 * vma, merges and splits can happen in a seamless way, just 3189 * using the existing file pgoff checks and manipulations. 3190 * Similarly in do_mmap_pgoff and in do_brk. 3191 */ 3192 if (vma_is_anonymous(vma)) { 3193 BUG_ON(vma->anon_vma); 3194 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT; 3195 } 3196 3197 vma_link(mm, vma, prev, rb_link, rb_parent); 3198 return 0; 3199 } 3200 3201 /* 3202 * Copy the vma structure to a new location in the same mm, 3203 * prior to moving page table entries, to effect an mremap move. 3204 */ 3205 struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, 3206 unsigned long addr, unsigned long len, pgoff_t pgoff, 3207 bool *need_rmap_locks) 3208 { 3209 struct vm_area_struct *vma = *vmap; 3210 unsigned long vma_start = vma->vm_start; 3211 struct mm_struct *mm = vma->vm_mm; 3212 struct vm_area_struct *new_vma, *prev; 3213 struct rb_node **rb_link, *rb_parent; 3214 bool faulted_in_anon_vma = true; 3215 3216 /* 3217 * If anonymous vma has not yet been faulted, update new pgoff 3218 * to match new location, to increase its chance of merging. 3219 */ 3220 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) { 3221 pgoff = addr >> PAGE_SHIFT; 3222 faulted_in_anon_vma = false; 3223 } 3224 3225 if (find_vma_links(mm, addr, addr + len, &prev, &rb_link, &rb_parent)) 3226 return NULL; /* should never get here */ 3227 new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags, 3228 vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma), 3229 vma->vm_userfaultfd_ctx); 3230 if (new_vma) { 3231 /* 3232 * Source vma may have been merged into new_vma 3233 */ 3234 if (unlikely(vma_start >= new_vma->vm_start && 3235 vma_start < new_vma->vm_end)) { 3236 /* 3237 * The only way we can get a vma_merge with 3238 * self during an mremap is if the vma hasn't 3239 * been faulted in yet and we were allowed to 3240 * reset the dst vma->vm_pgoff to the 3241 * destination address of the mremap to allow 3242 * the merge to happen. mremap must change the 3243 * vm_pgoff linearity between src and dst vmas 3244 * (in turn preventing a vma_merge) to be 3245 * safe. It is only safe to keep the vm_pgoff 3246 * linear if there are no pages mapped yet. 3247 */ 3248 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma); 3249 *vmap = vma = new_vma; 3250 } 3251 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff); 3252 } else { 3253 new_vma = vm_area_dup(vma); 3254 if (!new_vma) 3255 goto out; 3256 new_vma->vm_start = addr; 3257 new_vma->vm_end = addr + len; 3258 new_vma->vm_pgoff = pgoff; 3259 if (vma_dup_policy(vma, new_vma)) 3260 goto out_free_vma; 3261 if (anon_vma_clone(new_vma, vma)) 3262 goto out_free_mempol; 3263 if (new_vma->vm_file) 3264 get_file(new_vma->vm_file); 3265 if (new_vma->vm_ops && new_vma->vm_ops->open) 3266 new_vma->vm_ops->open(new_vma); 3267 vma_link(mm, new_vma, prev, rb_link, rb_parent); 3268 *need_rmap_locks = false; 3269 } 3270 return new_vma; 3271 3272 out_free_mempol: 3273 mpol_put(vma_policy(new_vma)); 3274 out_free_vma: 3275 vm_area_free(new_vma); 3276 out: 3277 return NULL; 3278 } 3279 3280 /* 3281 * Return true if the calling process may expand its vm space by the passed 3282 * number of pages 3283 */ 3284 bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) 3285 { 3286 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) 3287 return false; 3288 3289 if (is_data_mapping(flags) && 3290 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) { 3291 /* Workaround for Valgrind */ 3292 if (rlimit(RLIMIT_DATA) == 0 && 3293 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT) 3294 return true; 3295 3296 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n", 3297 current->comm, current->pid, 3298 (mm->data_vm + npages) << PAGE_SHIFT, 3299 rlimit(RLIMIT_DATA), 3300 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data"); 3301 3302 if (!ignore_rlimit_data) 3303 return false; 3304 } 3305 3306 return true; 3307 } 3308 3309 void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages) 3310 { 3311 mm->total_vm += npages; 3312 3313 if (is_exec_mapping(flags)) 3314 mm->exec_vm += npages; 3315 else if (is_stack_mapping(flags)) 3316 mm->stack_vm += npages; 3317 else if (is_data_mapping(flags)) 3318 mm->data_vm += npages; 3319 } 3320 3321 static vm_fault_t special_mapping_fault(struct vm_fault *vmf); 3322 3323 /* 3324 * Having a close hook prevents vma merging regardless of flags. 3325 */ 3326 static void special_mapping_close(struct vm_area_struct *vma) 3327 { 3328 } 3329 3330 static const char *special_mapping_name(struct vm_area_struct *vma) 3331 { 3332 return ((struct vm_special_mapping *)vma->vm_private_data)->name; 3333 } 3334 3335 static int special_mapping_mremap(struct vm_area_struct *new_vma) 3336 { 3337 struct vm_special_mapping *sm = new_vma->vm_private_data; 3338 3339 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm)) 3340 return -EFAULT; 3341 3342 if (sm->mremap) 3343 return sm->mremap(sm, new_vma); 3344 3345 return 0; 3346 } 3347 3348 static const struct vm_operations_struct special_mapping_vmops = { 3349 .close = special_mapping_close, 3350 .fault = special_mapping_fault, 3351 .mremap = special_mapping_mremap, 3352 .name = special_mapping_name, 3353 /* vDSO code relies that VVAR can't be accessed remotely */ 3354 .access = NULL, 3355 }; 3356 3357 static const struct vm_operations_struct legacy_special_mapping_vmops = { 3358 .close = special_mapping_close, 3359 .fault = special_mapping_fault, 3360 }; 3361 3362 static vm_fault_t special_mapping_fault(struct vm_fault *vmf) 3363 { 3364 struct vm_area_struct *vma = vmf->vma; 3365 pgoff_t pgoff; 3366 struct page **pages; 3367 3368 if (vma->vm_ops == &legacy_special_mapping_vmops) { 3369 pages = vma->vm_private_data; 3370 } else { 3371 struct vm_special_mapping *sm = vma->vm_private_data; 3372 3373 if (sm->fault) 3374 return sm->fault(sm, vmf->vma, vmf); 3375 3376 pages = sm->pages; 3377 } 3378 3379 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages) 3380 pgoff--; 3381 3382 if (*pages) { 3383 struct page *page = *pages; 3384 get_page(page); 3385 vmf->page = page; 3386 return 0; 3387 } 3388 3389 return VM_FAULT_SIGBUS; 3390 } 3391 3392 static struct vm_area_struct *__install_special_mapping( 3393 struct mm_struct *mm, 3394 unsigned long addr, unsigned long len, 3395 unsigned long vm_flags, void *priv, 3396 const struct vm_operations_struct *ops) 3397 { 3398 int ret; 3399 struct vm_area_struct *vma; 3400 3401 vma = vm_area_alloc(mm); 3402 if (unlikely(vma == NULL)) 3403 return ERR_PTR(-ENOMEM); 3404 3405 vma->vm_start = addr; 3406 vma->vm_end = addr + len; 3407 3408 vma->vm_flags = vm_flags | mm->def_flags | VM_DONTEXPAND | VM_SOFTDIRTY; 3409 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); 3410 3411 vma->vm_ops = ops; 3412 vma->vm_private_data = priv; 3413 3414 ret = insert_vm_struct(mm, vma); 3415 if (ret) 3416 goto out; 3417 3418 vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT); 3419 3420 perf_event_mmap(vma); 3421 3422 return vma; 3423 3424 out: 3425 vm_area_free(vma); 3426 return ERR_PTR(ret); 3427 } 3428 3429 bool vma_is_special_mapping(const struct vm_area_struct *vma, 3430 const struct vm_special_mapping *sm) 3431 { 3432 return vma->vm_private_data == sm && 3433 (vma->vm_ops == &special_mapping_vmops || 3434 vma->vm_ops == &legacy_special_mapping_vmops); 3435 } 3436 3437 /* 3438 * Called with mm->mmap_sem held for writing. 3439 * Insert a new vma covering the given region, with the given flags. 3440 * Its pages are supplied by the given array of struct page *. 3441 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated. 3442 * The region past the last page supplied will always produce SIGBUS. 3443 * The array pointer and the pages it points to are assumed to stay alive 3444 * for as long as this mapping might exist. 3445 */ 3446 struct vm_area_struct *_install_special_mapping( 3447 struct mm_struct *mm, 3448 unsigned long addr, unsigned long len, 3449 unsigned long vm_flags, const struct vm_special_mapping *spec) 3450 { 3451 return __install_special_mapping(mm, addr, len, vm_flags, (void *)spec, 3452 &special_mapping_vmops); 3453 } 3454 3455 int install_special_mapping(struct mm_struct *mm, 3456 unsigned long addr, unsigned long len, 3457 unsigned long vm_flags, struct page **pages) 3458 { 3459 struct vm_area_struct *vma = __install_special_mapping( 3460 mm, addr, len, vm_flags, (void *)pages, 3461 &legacy_special_mapping_vmops); 3462 3463 return PTR_ERR_OR_ZERO(vma); 3464 } 3465 3466 static DEFINE_MUTEX(mm_all_locks_mutex); 3467 3468 static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma) 3469 { 3470 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { 3471 /* 3472 * The LSB of head.next can't change from under us 3473 * because we hold the mm_all_locks_mutex. 3474 */ 3475 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_sem); 3476 /* 3477 * We can safely modify head.next after taking the 3478 * anon_vma->root->rwsem. If some other vma in this mm shares 3479 * the same anon_vma we won't take it again. 3480 * 3481 * No need of atomic instructions here, head.next 3482 * can't change from under us thanks to the 3483 * anon_vma->root->rwsem. 3484 */ 3485 if (__test_and_set_bit(0, (unsigned long *) 3486 &anon_vma->root->rb_root.rb_root.rb_node)) 3487 BUG(); 3488 } 3489 } 3490 3491 static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping) 3492 { 3493 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 3494 /* 3495 * AS_MM_ALL_LOCKS can't change from under us because 3496 * we hold the mm_all_locks_mutex. 3497 * 3498 * Operations on ->flags have to be atomic because 3499 * even if AS_MM_ALL_LOCKS is stable thanks to the 3500 * mm_all_locks_mutex, there may be other cpus 3501 * changing other bitflags in parallel to us. 3502 */ 3503 if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags)) 3504 BUG(); 3505 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_sem); 3506 } 3507 } 3508 3509 /* 3510 * This operation locks against the VM for all pte/vma/mm related 3511 * operations that could ever happen on a certain mm. This includes 3512 * vmtruncate, try_to_unmap, and all page faults. 3513 * 3514 * The caller must take the mmap_sem in write mode before calling 3515 * mm_take_all_locks(). The caller isn't allowed to release the 3516 * mmap_sem until mm_drop_all_locks() returns. 3517 * 3518 * mmap_sem in write mode is required in order to block all operations 3519 * that could modify pagetables and free pages without need of 3520 * altering the vma layout. It's also needed in write mode to avoid new 3521 * anon_vmas to be associated with existing vmas. 3522 * 3523 * A single task can't take more than one mm_take_all_locks() in a row 3524 * or it would deadlock. 3525 * 3526 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in 3527 * mapping->flags avoid to take the same lock twice, if more than one 3528 * vma in this mm is backed by the same anon_vma or address_space. 3529 * 3530 * We take locks in following order, accordingly to comment at beginning 3531 * of mm/rmap.c: 3532 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for 3533 * hugetlb mapping); 3534 * - all i_mmap_rwsem locks; 3535 * - all anon_vma->rwseml 3536 * 3537 * We can take all locks within these types randomly because the VM code 3538 * doesn't nest them and we protected from parallel mm_take_all_locks() by 3539 * mm_all_locks_mutex. 3540 * 3541 * mm_take_all_locks() and mm_drop_all_locks are expensive operations 3542 * that may have to take thousand of locks. 3543 * 3544 * mm_take_all_locks() can fail if it's interrupted by signals. 3545 */ 3546 int mm_take_all_locks(struct mm_struct *mm) 3547 { 3548 struct vm_area_struct *vma; 3549 struct anon_vma_chain *avc; 3550 3551 BUG_ON(down_read_trylock(&mm->mmap_sem)); 3552 3553 mutex_lock(&mm_all_locks_mutex); 3554 3555 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3556 if (signal_pending(current)) 3557 goto out_unlock; 3558 if (vma->vm_file && vma->vm_file->f_mapping && 3559 is_vm_hugetlb_page(vma)) 3560 vm_lock_mapping(mm, vma->vm_file->f_mapping); 3561 } 3562 3563 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3564 if (signal_pending(current)) 3565 goto out_unlock; 3566 if (vma->vm_file && vma->vm_file->f_mapping && 3567 !is_vm_hugetlb_page(vma)) 3568 vm_lock_mapping(mm, vma->vm_file->f_mapping); 3569 } 3570 3571 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3572 if (signal_pending(current)) 3573 goto out_unlock; 3574 if (vma->anon_vma) 3575 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 3576 vm_lock_anon_vma(mm, avc->anon_vma); 3577 } 3578 3579 return 0; 3580 3581 out_unlock: 3582 mm_drop_all_locks(mm); 3583 return -EINTR; 3584 } 3585 3586 static void vm_unlock_anon_vma(struct anon_vma *anon_vma) 3587 { 3588 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) { 3589 /* 3590 * The LSB of head.next can't change to 0 from under 3591 * us because we hold the mm_all_locks_mutex. 3592 * 3593 * We must however clear the bitflag before unlocking 3594 * the vma so the users using the anon_vma->rb_root will 3595 * never see our bitflag. 3596 * 3597 * No need of atomic instructions here, head.next 3598 * can't change from under us until we release the 3599 * anon_vma->root->rwsem. 3600 */ 3601 if (!__test_and_clear_bit(0, (unsigned long *) 3602 &anon_vma->root->rb_root.rb_root.rb_node)) 3603 BUG(); 3604 anon_vma_unlock_write(anon_vma); 3605 } 3606 } 3607 3608 static void vm_unlock_mapping(struct address_space *mapping) 3609 { 3610 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) { 3611 /* 3612 * AS_MM_ALL_LOCKS can't change to 0 from under us 3613 * because we hold the mm_all_locks_mutex. 3614 */ 3615 i_mmap_unlock_write(mapping); 3616 if (!test_and_clear_bit(AS_MM_ALL_LOCKS, 3617 &mapping->flags)) 3618 BUG(); 3619 } 3620 } 3621 3622 /* 3623 * The mmap_sem cannot be released by the caller until 3624 * mm_drop_all_locks() returns. 3625 */ 3626 void mm_drop_all_locks(struct mm_struct *mm) 3627 { 3628 struct vm_area_struct *vma; 3629 struct anon_vma_chain *avc; 3630 3631 BUG_ON(down_read_trylock(&mm->mmap_sem)); 3632 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex)); 3633 3634 for (vma = mm->mmap; vma; vma = vma->vm_next) { 3635 if (vma->anon_vma) 3636 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma) 3637 vm_unlock_anon_vma(avc->anon_vma); 3638 if (vma->vm_file && vma->vm_file->f_mapping) 3639 vm_unlock_mapping(vma->vm_file->f_mapping); 3640 } 3641 3642 mutex_unlock(&mm_all_locks_mutex); 3643 } 3644 3645 /* 3646 * initialise the percpu counter for VM 3647 */ 3648 void __init mmap_init(void) 3649 { 3650 int ret; 3651 3652 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); 3653 VM_BUG_ON(ret); 3654 } 3655 3656 /* 3657 * Initialise sysctl_user_reserve_kbytes. 3658 * 3659 * This is intended to prevent a user from starting a single memory hogging 3660 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER 3661 * mode. 3662 * 3663 * The default value is min(3% of free memory, 128MB) 3664 * 128MB is enough to recover with sshd/login, bash, and top/kill. 3665 */ 3666 static int init_user_reserve(void) 3667 { 3668 unsigned long free_kbytes; 3669 3670 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 3671 3672 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); 3673 return 0; 3674 } 3675 subsys_initcall(init_user_reserve); 3676 3677 /* 3678 * Initialise sysctl_admin_reserve_kbytes. 3679 * 3680 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin 3681 * to log in and kill a memory hogging process. 3682 * 3683 * Systems with more than 256MB will reserve 8MB, enough to recover 3684 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will 3685 * only reserve 3% of free pages by default. 3686 */ 3687 static int init_admin_reserve(void) 3688 { 3689 unsigned long free_kbytes; 3690 3691 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 3692 3693 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); 3694 return 0; 3695 } 3696 subsys_initcall(init_admin_reserve); 3697 3698 /* 3699 * Reinititalise user and admin reserves if memory is added or removed. 3700 * 3701 * The default user reserve max is 128MB, and the default max for the 3702 * admin reserve is 8MB. These are usually, but not always, enough to 3703 * enable recovery from a memory hogging process using login/sshd, a shell, 3704 * and tools like top. It may make sense to increase or even disable the 3705 * reserve depending on the existence of swap or variations in the recovery 3706 * tools. So, the admin may have changed them. 3707 * 3708 * If memory is added and the reserves have been eliminated or increased above 3709 * the default max, then we'll trust the admin. 3710 * 3711 * If memory is removed and there isn't enough free memory, then we 3712 * need to reset the reserves. 3713 * 3714 * Otherwise keep the reserve set by the admin. 3715 */ 3716 static int reserve_mem_notifier(struct notifier_block *nb, 3717 unsigned long action, void *data) 3718 { 3719 unsigned long tmp, free_kbytes; 3720 3721 switch (action) { 3722 case MEM_ONLINE: 3723 /* Default max is 128MB. Leave alone if modified by operator. */ 3724 tmp = sysctl_user_reserve_kbytes; 3725 if (0 < tmp && tmp < (1UL << 17)) 3726 init_user_reserve(); 3727 3728 /* Default max is 8MB. Leave alone if modified by operator. */ 3729 tmp = sysctl_admin_reserve_kbytes; 3730 if (0 < tmp && tmp < (1UL << 13)) 3731 init_admin_reserve(); 3732 3733 break; 3734 case MEM_OFFLINE: 3735 free_kbytes = global_zone_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10); 3736 3737 if (sysctl_user_reserve_kbytes > free_kbytes) { 3738 init_user_reserve(); 3739 pr_info("vm.user_reserve_kbytes reset to %lu\n", 3740 sysctl_user_reserve_kbytes); 3741 } 3742 3743 if (sysctl_admin_reserve_kbytes > free_kbytes) { 3744 init_admin_reserve(); 3745 pr_info("vm.admin_reserve_kbytes reset to %lu\n", 3746 sysctl_admin_reserve_kbytes); 3747 } 3748 break; 3749 default: 3750 break; 3751 } 3752 return NOTIFY_OK; 3753 } 3754 3755 static struct notifier_block reserve_mem_nb = { 3756 .notifier_call = reserve_mem_notifier, 3757 }; 3758 3759 static int __meminit init_reserve_notifier(void) 3760 { 3761 if (register_hotmemory_notifier(&reserve_mem_nb)) 3762 pr_err("Failed registering memory add/remove notifier for admin reserve\n"); 3763 3764 return 0; 3765 } 3766 subsys_initcall(init_reserve_notifier); 3767