1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/mm/nommu.c 4 * 5 * Replacement code for mm functions to support CPU's that don't 6 * have any form of memory management unit (thus no virtual memory). 7 * 8 * See Documentation/admin-guide/mm/nommu-mmap.rst 9 * 10 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com> 11 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com> 12 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org> 13 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com> 14 * Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org> 15 */ 16 17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 18 19 #include <linux/export.h> 20 #include <linux/mm.h> 21 #include <linux/sched/mm.h> 22 #include <linux/mman.h> 23 #include <linux/swap.h> 24 #include <linux/file.h> 25 #include <linux/highmem.h> 26 #include <linux/pagemap.h> 27 #include <linux/slab.h> 28 #include <linux/vmalloc.h> 29 #include <linux/backing-dev.h> 30 #include <linux/compiler.h> 31 #include <linux/mount.h> 32 #include <linux/personality.h> 33 #include <linux/security.h> 34 #include <linux/syscalls.h> 35 #include <linux/audit.h> 36 #include <linux/printk.h> 37 38 #include <linux/uaccess.h> 39 #include <linux/uio.h> 40 #include <asm/tlb.h> 41 #include <asm/tlbflush.h> 42 #include <asm/mmu_context.h> 43 #include "internal.h" 44 45 void *high_memory; 46 EXPORT_SYMBOL(high_memory); 47 struct page *mem_map; 48 unsigned long max_mapnr; 49 EXPORT_SYMBOL(max_mapnr); 50 unsigned long highest_memmap_pfn; 51 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; 52 int heap_stack_gap = 0; 53 54 atomic_long_t mmap_pages_allocated; 55 56 EXPORT_SYMBOL(mem_map); 57 58 /* list of mapped, potentially shareable regions */ 59 static struct kmem_cache *vm_region_jar; 60 struct rb_root nommu_region_tree = RB_ROOT; 61 DECLARE_RWSEM(nommu_region_sem); 62 63 const struct vm_operations_struct generic_file_vm_ops = { 64 }; 65 66 /* 67 * Return the total memory allocated for this pointer, not 68 * just what the caller asked for. 69 * 70 * Doesn't have to be accurate, i.e. may have races. 71 */ 72 unsigned int kobjsize(const void *objp) 73 { 74 struct page *page; 75 76 /* 77 * If the object we have should not have ksize performed on it, 78 * return size of 0 79 */ 80 if (!objp || !virt_addr_valid(objp)) 81 return 0; 82 83 page = virt_to_head_page(objp); 84 85 /* 86 * If the allocator sets PageSlab, we know the pointer came from 87 * kmalloc(). 88 */ 89 if (PageSlab(page)) 90 return ksize(objp); 91 92 /* 93 * If it's not a compound page, see if we have a matching VMA 94 * region. This test is intentionally done in reverse order, 95 * so if there's no VMA, we still fall through and hand back 96 * PAGE_SIZE for 0-order pages. 97 */ 98 if (!PageCompound(page)) { 99 struct vm_area_struct *vma; 100 101 vma = find_vma(current->mm, (unsigned long)objp); 102 if (vma) 103 return vma->vm_end - vma->vm_start; 104 } 105 106 /* 107 * The ksize() function is only guaranteed to work for pointers 108 * returned by kmalloc(). So handle arbitrary pointers here. 109 */ 110 return page_size(page); 111 } 112 113 void vfree(const void *addr) 114 { 115 kfree(addr); 116 } 117 EXPORT_SYMBOL(vfree); 118 119 void *__vmalloc_noprof(unsigned long size, gfp_t gfp_mask) 120 { 121 /* 122 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() 123 * returns only a logical address. 124 */ 125 return kmalloc_noprof(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 126 } 127 EXPORT_SYMBOL(__vmalloc_noprof); 128 129 void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align, 130 unsigned long start, unsigned long end, gfp_t gfp_mask, 131 pgprot_t prot, unsigned long vm_flags, int node, 132 const void *caller) 133 { 134 return __vmalloc_noprof(size, gfp_mask); 135 } 136 137 void *__vmalloc_node_noprof(unsigned long size, unsigned long align, gfp_t gfp_mask, 138 int node, const void *caller) 139 { 140 return __vmalloc_noprof(size, gfp_mask); 141 } 142 143 static void *__vmalloc_user_flags(unsigned long size, gfp_t flags) 144 { 145 void *ret; 146 147 ret = __vmalloc(size, flags); 148 if (ret) { 149 struct vm_area_struct *vma; 150 151 mmap_write_lock(current->mm); 152 vma = find_vma(current->mm, (unsigned long)ret); 153 if (vma) 154 vm_flags_set(vma, VM_USERMAP); 155 mmap_write_unlock(current->mm); 156 } 157 158 return ret; 159 } 160 161 void *vmalloc_user_noprof(unsigned long size) 162 { 163 return __vmalloc_user_flags(size, GFP_KERNEL | __GFP_ZERO); 164 } 165 EXPORT_SYMBOL(vmalloc_user_noprof); 166 167 struct page *vmalloc_to_page(const void *addr) 168 { 169 return virt_to_page(addr); 170 } 171 EXPORT_SYMBOL(vmalloc_to_page); 172 173 unsigned long vmalloc_to_pfn(const void *addr) 174 { 175 return page_to_pfn(virt_to_page(addr)); 176 } 177 EXPORT_SYMBOL(vmalloc_to_pfn); 178 179 long vread_iter(struct iov_iter *iter, const char *addr, size_t count) 180 { 181 /* Don't allow overflow */ 182 if ((unsigned long) addr + count < count) 183 count = -(unsigned long) addr; 184 185 return copy_to_iter(addr, count, iter); 186 } 187 188 /* 189 * vmalloc - allocate virtually contiguous memory 190 * 191 * @size: allocation size 192 * 193 * Allocate enough pages to cover @size from the page level 194 * allocator and map them into contiguous kernel virtual space. 195 * 196 * For tight control over page level allocator and protection flags 197 * use __vmalloc() instead. 198 */ 199 void *vmalloc_noprof(unsigned long size) 200 { 201 return __vmalloc_noprof(size, GFP_KERNEL); 202 } 203 EXPORT_SYMBOL(vmalloc_noprof); 204 205 void *vmalloc_huge_noprof(unsigned long size, gfp_t gfp_mask) __weak __alias(__vmalloc_noprof); 206 207 /* 208 * vzalloc - allocate virtually contiguous memory with zero fill 209 * 210 * @size: allocation size 211 * 212 * Allocate enough pages to cover @size from the page level 213 * allocator and map them into contiguous kernel virtual space. 214 * The memory allocated is set to zero. 215 * 216 * For tight control over page level allocator and protection flags 217 * use __vmalloc() instead. 218 */ 219 void *vzalloc_noprof(unsigned long size) 220 { 221 return __vmalloc_noprof(size, GFP_KERNEL | __GFP_ZERO); 222 } 223 EXPORT_SYMBOL(vzalloc_noprof); 224 225 /** 226 * vmalloc_node - allocate memory on a specific node 227 * @size: allocation size 228 * @node: numa node 229 * 230 * Allocate enough pages to cover @size from the page level 231 * allocator and map them into contiguous kernel virtual space. 232 * 233 * For tight control over page level allocator and protection flags 234 * use __vmalloc() instead. 235 */ 236 void *vmalloc_node_noprof(unsigned long size, int node) 237 { 238 return vmalloc_noprof(size); 239 } 240 EXPORT_SYMBOL(vmalloc_node_noprof); 241 242 /** 243 * vzalloc_node - allocate memory on a specific node with zero fill 244 * @size: allocation size 245 * @node: numa node 246 * 247 * Allocate enough pages to cover @size from the page level 248 * allocator and map them into contiguous kernel virtual space. 249 * The memory allocated is set to zero. 250 * 251 * For tight control over page level allocator and protection flags 252 * use __vmalloc() instead. 253 */ 254 void *vzalloc_node_noprof(unsigned long size, int node) 255 { 256 return vzalloc_noprof(size); 257 } 258 EXPORT_SYMBOL(vzalloc_node_noprof); 259 260 /** 261 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) 262 * @size: allocation size 263 * 264 * Allocate enough 32bit PA addressable pages to cover @size from the 265 * page level allocator and map them into contiguous kernel virtual space. 266 */ 267 void *vmalloc_32_noprof(unsigned long size) 268 { 269 return __vmalloc_noprof(size, GFP_KERNEL); 270 } 271 EXPORT_SYMBOL(vmalloc_32_noprof); 272 273 /** 274 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory 275 * @size: allocation size 276 * 277 * The resulting memory area is 32bit addressable and zeroed so it can be 278 * mapped to userspace without leaking data. 279 * 280 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to 281 * remap_vmalloc_range() are permissible. 282 */ 283 void *vmalloc_32_user_noprof(unsigned long size) 284 { 285 /* 286 * We'll have to sort out the ZONE_DMA bits for 64-bit, 287 * but for now this can simply use vmalloc_user() directly. 288 */ 289 return vmalloc_user_noprof(size); 290 } 291 EXPORT_SYMBOL(vmalloc_32_user_noprof); 292 293 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 294 { 295 BUG(); 296 return NULL; 297 } 298 EXPORT_SYMBOL(vmap); 299 300 void vunmap(const void *addr) 301 { 302 BUG(); 303 } 304 EXPORT_SYMBOL(vunmap); 305 306 void *vm_map_ram(struct page **pages, unsigned int count, int node) 307 { 308 BUG(); 309 return NULL; 310 } 311 EXPORT_SYMBOL(vm_map_ram); 312 313 void vm_unmap_ram(const void *mem, unsigned int count) 314 { 315 BUG(); 316 } 317 EXPORT_SYMBOL(vm_unmap_ram); 318 319 void vm_unmap_aliases(void) 320 { 321 } 322 EXPORT_SYMBOL_GPL(vm_unmap_aliases); 323 324 void free_vm_area(struct vm_struct *area) 325 { 326 BUG(); 327 } 328 EXPORT_SYMBOL_GPL(free_vm_area); 329 330 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 331 struct page *page) 332 { 333 return -EINVAL; 334 } 335 EXPORT_SYMBOL(vm_insert_page); 336 337 int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr, 338 struct page **pages, unsigned long *num) 339 { 340 return -EINVAL; 341 } 342 EXPORT_SYMBOL(vm_insert_pages); 343 344 int vm_map_pages(struct vm_area_struct *vma, struct page **pages, 345 unsigned long num) 346 { 347 return -EINVAL; 348 } 349 EXPORT_SYMBOL(vm_map_pages); 350 351 int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages, 352 unsigned long num) 353 { 354 return -EINVAL; 355 } 356 EXPORT_SYMBOL(vm_map_pages_zero); 357 358 /* 359 * sys_brk() for the most part doesn't need the global kernel 360 * lock, except when an application is doing something nasty 361 * like trying to un-brk an area that has already been mapped 362 * to a regular file. in this case, the unmapping will need 363 * to invoke file system routines that need the global lock. 364 */ 365 SYSCALL_DEFINE1(brk, unsigned long, brk) 366 { 367 struct mm_struct *mm = current->mm; 368 369 if (brk < mm->start_brk || brk > mm->context.end_brk) 370 return mm->brk; 371 372 if (mm->brk == brk) 373 return mm->brk; 374 375 /* 376 * Always allow shrinking brk 377 */ 378 if (brk <= mm->brk) { 379 mm->brk = brk; 380 return brk; 381 } 382 383 /* 384 * Ok, looks good - let it rip. 385 */ 386 flush_icache_user_range(mm->brk, brk); 387 return mm->brk = brk; 388 } 389 390 /* 391 * initialise the percpu counter for VM and region record slabs 392 */ 393 void __init mmap_init(void) 394 { 395 int ret; 396 397 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL); 398 VM_BUG_ON(ret); 399 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC|SLAB_ACCOUNT); 400 } 401 402 /* 403 * validate the region tree 404 * - the caller must hold the region lock 405 */ 406 #ifdef CONFIG_DEBUG_NOMMU_REGIONS 407 static noinline void validate_nommu_regions(void) 408 { 409 struct vm_region *region, *last; 410 struct rb_node *p, *lastp; 411 412 lastp = rb_first(&nommu_region_tree); 413 if (!lastp) 414 return; 415 416 last = rb_entry(lastp, struct vm_region, vm_rb); 417 BUG_ON(last->vm_end <= last->vm_start); 418 BUG_ON(last->vm_top < last->vm_end); 419 420 while ((p = rb_next(lastp))) { 421 region = rb_entry(p, struct vm_region, vm_rb); 422 last = rb_entry(lastp, struct vm_region, vm_rb); 423 424 BUG_ON(region->vm_end <= region->vm_start); 425 BUG_ON(region->vm_top < region->vm_end); 426 BUG_ON(region->vm_start < last->vm_top); 427 428 lastp = p; 429 } 430 } 431 #else 432 static void validate_nommu_regions(void) 433 { 434 } 435 #endif 436 437 /* 438 * add a region into the global tree 439 */ 440 static void add_nommu_region(struct vm_region *region) 441 { 442 struct vm_region *pregion; 443 struct rb_node **p, *parent; 444 445 validate_nommu_regions(); 446 447 parent = NULL; 448 p = &nommu_region_tree.rb_node; 449 while (*p) { 450 parent = *p; 451 pregion = rb_entry(parent, struct vm_region, vm_rb); 452 if (region->vm_start < pregion->vm_start) 453 p = &(*p)->rb_left; 454 else if (region->vm_start > pregion->vm_start) 455 p = &(*p)->rb_right; 456 else if (pregion == region) 457 return; 458 else 459 BUG(); 460 } 461 462 rb_link_node(®ion->vm_rb, parent, p); 463 rb_insert_color(®ion->vm_rb, &nommu_region_tree); 464 465 validate_nommu_regions(); 466 } 467 468 /* 469 * delete a region from the global tree 470 */ 471 static void delete_nommu_region(struct vm_region *region) 472 { 473 BUG_ON(!nommu_region_tree.rb_node); 474 475 validate_nommu_regions(); 476 rb_erase(®ion->vm_rb, &nommu_region_tree); 477 validate_nommu_regions(); 478 } 479 480 /* 481 * free a contiguous series of pages 482 */ 483 static void free_page_series(unsigned long from, unsigned long to) 484 { 485 for (; from < to; from += PAGE_SIZE) { 486 struct page *page = virt_to_page((void *)from); 487 488 atomic_long_dec(&mmap_pages_allocated); 489 put_page(page); 490 } 491 } 492 493 /* 494 * release a reference to a region 495 * - the caller must hold the region semaphore for writing, which this releases 496 * - the region may not have been added to the tree yet, in which case vm_top 497 * will equal vm_start 498 */ 499 static void __put_nommu_region(struct vm_region *region) 500 __releases(nommu_region_sem) 501 { 502 BUG_ON(!nommu_region_tree.rb_node); 503 504 if (--region->vm_usage == 0) { 505 if (region->vm_top > region->vm_start) 506 delete_nommu_region(region); 507 up_write(&nommu_region_sem); 508 509 if (region->vm_file) 510 fput(region->vm_file); 511 512 /* IO memory and memory shared directly out of the pagecache 513 * from ramfs/tmpfs mustn't be released here */ 514 if (region->vm_flags & VM_MAPPED_COPY) 515 free_page_series(region->vm_start, region->vm_top); 516 kmem_cache_free(vm_region_jar, region); 517 } else { 518 up_write(&nommu_region_sem); 519 } 520 } 521 522 /* 523 * release a reference to a region 524 */ 525 static void put_nommu_region(struct vm_region *region) 526 { 527 down_write(&nommu_region_sem); 528 __put_nommu_region(region); 529 } 530 531 static void setup_vma_to_mm(struct vm_area_struct *vma, struct mm_struct *mm) 532 { 533 vma->vm_mm = mm; 534 535 /* add the VMA to the mapping */ 536 if (vma->vm_file) { 537 struct address_space *mapping = vma->vm_file->f_mapping; 538 539 i_mmap_lock_write(mapping); 540 flush_dcache_mmap_lock(mapping); 541 vma_interval_tree_insert(vma, &mapping->i_mmap); 542 flush_dcache_mmap_unlock(mapping); 543 i_mmap_unlock_write(mapping); 544 } 545 } 546 547 static void cleanup_vma_from_mm(struct vm_area_struct *vma) 548 { 549 vma->vm_mm->map_count--; 550 /* remove the VMA from the mapping */ 551 if (vma->vm_file) { 552 struct address_space *mapping; 553 mapping = vma->vm_file->f_mapping; 554 555 i_mmap_lock_write(mapping); 556 flush_dcache_mmap_lock(mapping); 557 vma_interval_tree_remove(vma, &mapping->i_mmap); 558 flush_dcache_mmap_unlock(mapping); 559 i_mmap_unlock_write(mapping); 560 } 561 } 562 563 /* 564 * delete a VMA from its owning mm_struct and address space 565 */ 566 static int delete_vma_from_mm(struct vm_area_struct *vma) 567 { 568 VMA_ITERATOR(vmi, vma->vm_mm, vma->vm_start); 569 570 vma_iter_config(&vmi, vma->vm_start, vma->vm_end); 571 if (vma_iter_prealloc(&vmi, vma)) { 572 pr_warn("Allocation of vma tree for process %d failed\n", 573 current->pid); 574 return -ENOMEM; 575 } 576 cleanup_vma_from_mm(vma); 577 578 /* remove from the MM's tree and list */ 579 vma_iter_clear(&vmi); 580 return 0; 581 } 582 /* 583 * destroy a VMA record 584 */ 585 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) 586 { 587 if (vma->vm_ops && vma->vm_ops->close) 588 vma->vm_ops->close(vma); 589 if (vma->vm_file) 590 fput(vma->vm_file); 591 put_nommu_region(vma->vm_region); 592 vm_area_free(vma); 593 } 594 595 struct vm_area_struct *find_vma_intersection(struct mm_struct *mm, 596 unsigned long start_addr, 597 unsigned long end_addr) 598 { 599 unsigned long index = start_addr; 600 601 mmap_assert_locked(mm); 602 return mt_find(&mm->mm_mt, &index, end_addr - 1); 603 } 604 EXPORT_SYMBOL(find_vma_intersection); 605 606 /* 607 * look up the first VMA in which addr resides, NULL if none 608 * - should be called with mm->mmap_lock at least held readlocked 609 */ 610 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 611 { 612 VMA_ITERATOR(vmi, mm, addr); 613 614 return vma_iter_load(&vmi); 615 } 616 EXPORT_SYMBOL(find_vma); 617 618 /* 619 * At least xtensa ends up having protection faults even with no 620 * MMU.. No stack expansion, at least. 621 */ 622 struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm, 623 unsigned long addr, struct pt_regs *regs) 624 { 625 struct vm_area_struct *vma; 626 627 mmap_read_lock(mm); 628 vma = vma_lookup(mm, addr); 629 if (!vma) 630 mmap_read_unlock(mm); 631 return vma; 632 } 633 634 /* 635 * expand a stack to a given address 636 * - not supported under NOMMU conditions 637 */ 638 int expand_stack_locked(struct vm_area_struct *vma, unsigned long addr) 639 { 640 return -ENOMEM; 641 } 642 643 struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr) 644 { 645 mmap_read_unlock(mm); 646 return NULL; 647 } 648 649 /* 650 * look up the first VMA exactly that exactly matches addr 651 * - should be called with mm->mmap_lock at least held readlocked 652 */ 653 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 654 unsigned long addr, 655 unsigned long len) 656 { 657 struct vm_area_struct *vma; 658 unsigned long end = addr + len; 659 VMA_ITERATOR(vmi, mm, addr); 660 661 vma = vma_iter_load(&vmi); 662 if (!vma) 663 return NULL; 664 if (vma->vm_start != addr) 665 return NULL; 666 if (vma->vm_end != end) 667 return NULL; 668 669 return vma; 670 } 671 672 /* 673 * determine whether a mapping should be permitted and, if so, what sort of 674 * mapping we're capable of supporting 675 */ 676 static int validate_mmap_request(struct file *file, 677 unsigned long addr, 678 unsigned long len, 679 unsigned long prot, 680 unsigned long flags, 681 unsigned long pgoff, 682 unsigned long *_capabilities) 683 { 684 unsigned long capabilities, rlen; 685 int ret; 686 687 /* do the simple checks first */ 688 if (flags & MAP_FIXED) 689 return -EINVAL; 690 691 if ((flags & MAP_TYPE) != MAP_PRIVATE && 692 (flags & MAP_TYPE) != MAP_SHARED) 693 return -EINVAL; 694 695 if (!len) 696 return -EINVAL; 697 698 /* Careful about overflows.. */ 699 rlen = PAGE_ALIGN(len); 700 if (!rlen || rlen > TASK_SIZE) 701 return -ENOMEM; 702 703 /* offset overflow? */ 704 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) 705 return -EOVERFLOW; 706 707 if (file) { 708 /* files must support mmap */ 709 if (!file->f_op->mmap) 710 return -ENODEV; 711 712 /* work out if what we've got could possibly be shared 713 * - we support chardevs that provide their own "memory" 714 * - we support files/blockdevs that are memory backed 715 */ 716 if (file->f_op->mmap_capabilities) { 717 capabilities = file->f_op->mmap_capabilities(file); 718 } else { 719 /* no explicit capabilities set, so assume some 720 * defaults */ 721 switch (file_inode(file)->i_mode & S_IFMT) { 722 case S_IFREG: 723 case S_IFBLK: 724 capabilities = NOMMU_MAP_COPY; 725 break; 726 727 case S_IFCHR: 728 capabilities = 729 NOMMU_MAP_DIRECT | 730 NOMMU_MAP_READ | 731 NOMMU_MAP_WRITE; 732 break; 733 734 default: 735 return -EINVAL; 736 } 737 } 738 739 /* eliminate any capabilities that we can't support on this 740 * device */ 741 if (!file->f_op->get_unmapped_area) 742 capabilities &= ~NOMMU_MAP_DIRECT; 743 if (!(file->f_mode & FMODE_CAN_READ)) 744 capabilities &= ~NOMMU_MAP_COPY; 745 746 /* The file shall have been opened with read permission. */ 747 if (!(file->f_mode & FMODE_READ)) 748 return -EACCES; 749 750 if (flags & MAP_SHARED) { 751 /* do checks for writing, appending and locking */ 752 if ((prot & PROT_WRITE) && 753 !(file->f_mode & FMODE_WRITE)) 754 return -EACCES; 755 756 if (IS_APPEND(file_inode(file)) && 757 (file->f_mode & FMODE_WRITE)) 758 return -EACCES; 759 760 if (!(capabilities & NOMMU_MAP_DIRECT)) 761 return -ENODEV; 762 763 /* we mustn't privatise shared mappings */ 764 capabilities &= ~NOMMU_MAP_COPY; 765 } else { 766 /* we're going to read the file into private memory we 767 * allocate */ 768 if (!(capabilities & NOMMU_MAP_COPY)) 769 return -ENODEV; 770 771 /* we don't permit a private writable mapping to be 772 * shared with the backing device */ 773 if (prot & PROT_WRITE) 774 capabilities &= ~NOMMU_MAP_DIRECT; 775 } 776 777 if (capabilities & NOMMU_MAP_DIRECT) { 778 if (((prot & PROT_READ) && !(capabilities & NOMMU_MAP_READ)) || 779 ((prot & PROT_WRITE) && !(capabilities & NOMMU_MAP_WRITE)) || 780 ((prot & PROT_EXEC) && !(capabilities & NOMMU_MAP_EXEC)) 781 ) { 782 capabilities &= ~NOMMU_MAP_DIRECT; 783 if (flags & MAP_SHARED) { 784 pr_warn("MAP_SHARED not completely supported on !MMU\n"); 785 return -EINVAL; 786 } 787 } 788 } 789 790 /* handle executable mappings and implied executable 791 * mappings */ 792 if (path_noexec(&file->f_path)) { 793 if (prot & PROT_EXEC) 794 return -EPERM; 795 } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 796 /* handle implication of PROT_EXEC by PROT_READ */ 797 if (current->personality & READ_IMPLIES_EXEC) { 798 if (capabilities & NOMMU_MAP_EXEC) 799 prot |= PROT_EXEC; 800 } 801 } else if ((prot & PROT_READ) && 802 (prot & PROT_EXEC) && 803 !(capabilities & NOMMU_MAP_EXEC) 804 ) { 805 /* backing file is not executable, try to copy */ 806 capabilities &= ~NOMMU_MAP_DIRECT; 807 } 808 } else { 809 /* anonymous mappings are always memory backed and can be 810 * privately mapped 811 */ 812 capabilities = NOMMU_MAP_COPY; 813 814 /* handle PROT_EXEC implication by PROT_READ */ 815 if ((prot & PROT_READ) && 816 (current->personality & READ_IMPLIES_EXEC)) 817 prot |= PROT_EXEC; 818 } 819 820 /* allow the security API to have its say */ 821 ret = security_mmap_addr(addr); 822 if (ret < 0) 823 return ret; 824 825 /* looks okay */ 826 *_capabilities = capabilities; 827 return 0; 828 } 829 830 /* 831 * we've determined that we can make the mapping, now translate what we 832 * now know into VMA flags 833 */ 834 static unsigned long determine_vm_flags(struct file *file, 835 unsigned long prot, 836 unsigned long flags, 837 unsigned long capabilities) 838 { 839 unsigned long vm_flags; 840 841 vm_flags = calc_vm_prot_bits(prot, 0) | calc_vm_flag_bits(flags); 842 843 if (!file) { 844 /* 845 * MAP_ANONYMOUS. MAP_SHARED is mapped to MAP_PRIVATE, because 846 * there is no fork(). 847 */ 848 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 849 } else if (flags & MAP_PRIVATE) { 850 /* MAP_PRIVATE file mapping */ 851 if (capabilities & NOMMU_MAP_DIRECT) 852 vm_flags |= (capabilities & NOMMU_VMFLAGS); 853 else 854 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 855 856 if (!(prot & PROT_WRITE) && !current->ptrace) 857 /* 858 * R/O private file mapping which cannot be used to 859 * modify memory, especially also not via active ptrace 860 * (e.g., set breakpoints) or later by upgrading 861 * permissions (no mprotect()). We can try overlaying 862 * the file mapping, which will work e.g., on chardevs, 863 * ramfs/tmpfs/shmfs and romfs/cramf. 864 */ 865 vm_flags |= VM_MAYOVERLAY; 866 } else { 867 /* MAP_SHARED file mapping: NOMMU_MAP_DIRECT is set. */ 868 vm_flags |= VM_SHARED | VM_MAYSHARE | 869 (capabilities & NOMMU_VMFLAGS); 870 } 871 872 return vm_flags; 873 } 874 875 /* 876 * set up a shared mapping on a file (the driver or filesystem provides and 877 * pins the storage) 878 */ 879 static int do_mmap_shared_file(struct vm_area_struct *vma) 880 { 881 int ret; 882 883 ret = call_mmap(vma->vm_file, vma); 884 if (ret == 0) { 885 vma->vm_region->vm_top = vma->vm_region->vm_end; 886 return 0; 887 } 888 if (ret != -ENOSYS) 889 return ret; 890 891 /* getting -ENOSYS indicates that direct mmap isn't possible (as 892 * opposed to tried but failed) so we can only give a suitable error as 893 * it's not possible to make a private copy if MAP_SHARED was given */ 894 return -ENODEV; 895 } 896 897 /* 898 * set up a private mapping or an anonymous shared mapping 899 */ 900 static int do_mmap_private(struct vm_area_struct *vma, 901 struct vm_region *region, 902 unsigned long len, 903 unsigned long capabilities) 904 { 905 unsigned long total, point; 906 void *base; 907 int ret, order; 908 909 /* 910 * Invoke the file's mapping function so that it can keep track of 911 * shared mappings on devices or memory. VM_MAYOVERLAY will be set if 912 * it may attempt to share, which will make is_nommu_shared_mapping() 913 * happy. 914 */ 915 if (capabilities & NOMMU_MAP_DIRECT) { 916 ret = call_mmap(vma->vm_file, vma); 917 /* shouldn't return success if we're not sharing */ 918 if (WARN_ON_ONCE(!is_nommu_shared_mapping(vma->vm_flags))) 919 ret = -ENOSYS; 920 if (ret == 0) { 921 vma->vm_region->vm_top = vma->vm_region->vm_end; 922 return 0; 923 } 924 if (ret != -ENOSYS) 925 return ret; 926 927 /* getting an ENOSYS error indicates that direct mmap isn't 928 * possible (as opposed to tried but failed) so we'll try to 929 * make a private copy of the data and map that instead */ 930 } 931 932 933 /* allocate some memory to hold the mapping 934 * - note that this may not return a page-aligned address if the object 935 * we're allocating is smaller than a page 936 */ 937 order = get_order(len); 938 total = 1 << order; 939 point = len >> PAGE_SHIFT; 940 941 /* we don't want to allocate a power-of-2 sized page set */ 942 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) 943 total = point; 944 945 base = alloc_pages_exact(total << PAGE_SHIFT, GFP_KERNEL); 946 if (!base) 947 goto enomem; 948 949 atomic_long_add(total, &mmap_pages_allocated); 950 951 vm_flags_set(vma, VM_MAPPED_COPY); 952 region->vm_flags = vma->vm_flags; 953 region->vm_start = (unsigned long) base; 954 region->vm_end = region->vm_start + len; 955 region->vm_top = region->vm_start + (total << PAGE_SHIFT); 956 957 vma->vm_start = region->vm_start; 958 vma->vm_end = region->vm_start + len; 959 960 if (vma->vm_file) { 961 /* read the contents of a file into the copy */ 962 loff_t fpos; 963 964 fpos = vma->vm_pgoff; 965 fpos <<= PAGE_SHIFT; 966 967 ret = kernel_read(vma->vm_file, base, len, &fpos); 968 if (ret < 0) 969 goto error_free; 970 971 /* clear the last little bit */ 972 if (ret < len) 973 memset(base + ret, 0, len - ret); 974 975 } else { 976 vma_set_anonymous(vma); 977 } 978 979 return 0; 980 981 error_free: 982 free_page_series(region->vm_start, region->vm_top); 983 region->vm_start = vma->vm_start = 0; 984 region->vm_end = vma->vm_end = 0; 985 region->vm_top = 0; 986 return ret; 987 988 enomem: 989 pr_err("Allocation of length %lu from process %d (%s) failed\n", 990 len, current->pid, current->comm); 991 show_mem(); 992 return -ENOMEM; 993 } 994 995 /* 996 * handle mapping creation for uClinux 997 */ 998 unsigned long do_mmap(struct file *file, 999 unsigned long addr, 1000 unsigned long len, 1001 unsigned long prot, 1002 unsigned long flags, 1003 vm_flags_t vm_flags, 1004 unsigned long pgoff, 1005 unsigned long *populate, 1006 struct list_head *uf) 1007 { 1008 struct vm_area_struct *vma; 1009 struct vm_region *region; 1010 struct rb_node *rb; 1011 unsigned long capabilities, result; 1012 int ret; 1013 VMA_ITERATOR(vmi, current->mm, 0); 1014 1015 *populate = 0; 1016 1017 /* decide whether we should attempt the mapping, and if so what sort of 1018 * mapping */ 1019 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 1020 &capabilities); 1021 if (ret < 0) 1022 return ret; 1023 1024 /* we ignore the address hint */ 1025 addr = 0; 1026 len = PAGE_ALIGN(len); 1027 1028 /* we've determined that we can make the mapping, now translate what we 1029 * now know into VMA flags */ 1030 vm_flags |= determine_vm_flags(file, prot, flags, capabilities); 1031 1032 1033 /* we're going to need to record the mapping */ 1034 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); 1035 if (!region) 1036 goto error_getting_region; 1037 1038 vma = vm_area_alloc(current->mm); 1039 if (!vma) 1040 goto error_getting_vma; 1041 1042 region->vm_usage = 1; 1043 region->vm_flags = vm_flags; 1044 region->vm_pgoff = pgoff; 1045 1046 vm_flags_init(vma, vm_flags); 1047 vma->vm_pgoff = pgoff; 1048 1049 if (file) { 1050 region->vm_file = get_file(file); 1051 vma->vm_file = get_file(file); 1052 } 1053 1054 down_write(&nommu_region_sem); 1055 1056 /* if we want to share, we need to check for regions created by other 1057 * mmap() calls that overlap with our proposed mapping 1058 * - we can only share with a superset match on most regular files 1059 * - shared mappings on character devices and memory backed files are 1060 * permitted to overlap inexactly as far as we are concerned for in 1061 * these cases, sharing is handled in the driver or filesystem rather 1062 * than here 1063 */ 1064 if (is_nommu_shared_mapping(vm_flags)) { 1065 struct vm_region *pregion; 1066 unsigned long pglen, rpglen, pgend, rpgend, start; 1067 1068 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1069 pgend = pgoff + pglen; 1070 1071 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { 1072 pregion = rb_entry(rb, struct vm_region, vm_rb); 1073 1074 if (!is_nommu_shared_mapping(pregion->vm_flags)) 1075 continue; 1076 1077 /* search for overlapping mappings on the same file */ 1078 if (file_inode(pregion->vm_file) != 1079 file_inode(file)) 1080 continue; 1081 1082 if (pregion->vm_pgoff >= pgend) 1083 continue; 1084 1085 rpglen = pregion->vm_end - pregion->vm_start; 1086 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1087 rpgend = pregion->vm_pgoff + rpglen; 1088 if (pgoff >= rpgend) 1089 continue; 1090 1091 /* handle inexactly overlapping matches between 1092 * mappings */ 1093 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && 1094 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { 1095 /* new mapping is not a subset of the region */ 1096 if (!(capabilities & NOMMU_MAP_DIRECT)) 1097 goto sharing_violation; 1098 continue; 1099 } 1100 1101 /* we've found a region we can share */ 1102 pregion->vm_usage++; 1103 vma->vm_region = pregion; 1104 start = pregion->vm_start; 1105 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; 1106 vma->vm_start = start; 1107 vma->vm_end = start + len; 1108 1109 if (pregion->vm_flags & VM_MAPPED_COPY) 1110 vm_flags_set(vma, VM_MAPPED_COPY); 1111 else { 1112 ret = do_mmap_shared_file(vma); 1113 if (ret < 0) { 1114 vma->vm_region = NULL; 1115 vma->vm_start = 0; 1116 vma->vm_end = 0; 1117 pregion->vm_usage--; 1118 pregion = NULL; 1119 goto error_just_free; 1120 } 1121 } 1122 fput(region->vm_file); 1123 kmem_cache_free(vm_region_jar, region); 1124 region = pregion; 1125 result = start; 1126 goto share; 1127 } 1128 1129 /* obtain the address at which to make a shared mapping 1130 * - this is the hook for quasi-memory character devices to 1131 * tell us the location of a shared mapping 1132 */ 1133 if (capabilities & NOMMU_MAP_DIRECT) { 1134 addr = file->f_op->get_unmapped_area(file, addr, len, 1135 pgoff, flags); 1136 if (IS_ERR_VALUE(addr)) { 1137 ret = addr; 1138 if (ret != -ENOSYS) 1139 goto error_just_free; 1140 1141 /* the driver refused to tell us where to site 1142 * the mapping so we'll have to attempt to copy 1143 * it */ 1144 ret = -ENODEV; 1145 if (!(capabilities & NOMMU_MAP_COPY)) 1146 goto error_just_free; 1147 1148 capabilities &= ~NOMMU_MAP_DIRECT; 1149 } else { 1150 vma->vm_start = region->vm_start = addr; 1151 vma->vm_end = region->vm_end = addr + len; 1152 } 1153 } 1154 } 1155 1156 vma->vm_region = region; 1157 1158 /* set up the mapping 1159 * - the region is filled in if NOMMU_MAP_DIRECT is still set 1160 */ 1161 if (file && vma->vm_flags & VM_SHARED) 1162 ret = do_mmap_shared_file(vma); 1163 else 1164 ret = do_mmap_private(vma, region, len, capabilities); 1165 if (ret < 0) 1166 goto error_just_free; 1167 add_nommu_region(region); 1168 1169 /* clear anonymous mappings that don't ask for uninitialized data */ 1170 if (!vma->vm_file && 1171 (!IS_ENABLED(CONFIG_MMAP_ALLOW_UNINITIALIZED) || 1172 !(flags & MAP_UNINITIALIZED))) 1173 memset((void *)region->vm_start, 0, 1174 region->vm_end - region->vm_start); 1175 1176 /* okay... we have a mapping; now we have to register it */ 1177 result = vma->vm_start; 1178 1179 current->mm->total_vm += len >> PAGE_SHIFT; 1180 1181 share: 1182 BUG_ON(!vma->vm_region); 1183 vma_iter_config(&vmi, vma->vm_start, vma->vm_end); 1184 if (vma_iter_prealloc(&vmi, vma)) 1185 goto error_just_free; 1186 1187 setup_vma_to_mm(vma, current->mm); 1188 current->mm->map_count++; 1189 /* add the VMA to the tree */ 1190 vma_iter_store(&vmi, vma); 1191 1192 /* we flush the region from the icache only when the first executable 1193 * mapping of it is made */ 1194 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { 1195 flush_icache_user_range(region->vm_start, region->vm_end); 1196 region->vm_icache_flushed = true; 1197 } 1198 1199 up_write(&nommu_region_sem); 1200 1201 return result; 1202 1203 error_just_free: 1204 up_write(&nommu_region_sem); 1205 error: 1206 vma_iter_free(&vmi); 1207 if (region->vm_file) 1208 fput(region->vm_file); 1209 kmem_cache_free(vm_region_jar, region); 1210 if (vma->vm_file) 1211 fput(vma->vm_file); 1212 vm_area_free(vma); 1213 return ret; 1214 1215 sharing_violation: 1216 up_write(&nommu_region_sem); 1217 pr_warn("Attempt to share mismatched mappings\n"); 1218 ret = -EINVAL; 1219 goto error; 1220 1221 error_getting_vma: 1222 kmem_cache_free(vm_region_jar, region); 1223 pr_warn("Allocation of vma for %lu byte allocation from process %d failed\n", 1224 len, current->pid); 1225 show_mem(); 1226 return -ENOMEM; 1227 1228 error_getting_region: 1229 pr_warn("Allocation of vm region for %lu byte allocation from process %d failed\n", 1230 len, current->pid); 1231 show_mem(); 1232 return -ENOMEM; 1233 } 1234 1235 unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, 1236 unsigned long prot, unsigned long flags, 1237 unsigned long fd, unsigned long pgoff) 1238 { 1239 struct file *file = NULL; 1240 unsigned long retval = -EBADF; 1241 1242 audit_mmap_fd(fd, flags); 1243 if (!(flags & MAP_ANONYMOUS)) { 1244 file = fget(fd); 1245 if (!file) 1246 goto out; 1247 } 1248 1249 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1250 1251 if (file) 1252 fput(file); 1253 out: 1254 return retval; 1255 } 1256 1257 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1258 unsigned long, prot, unsigned long, flags, 1259 unsigned long, fd, unsigned long, pgoff) 1260 { 1261 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff); 1262 } 1263 1264 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1265 struct mmap_arg_struct { 1266 unsigned long addr; 1267 unsigned long len; 1268 unsigned long prot; 1269 unsigned long flags; 1270 unsigned long fd; 1271 unsigned long offset; 1272 }; 1273 1274 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1275 { 1276 struct mmap_arg_struct a; 1277 1278 if (copy_from_user(&a, arg, sizeof(a))) 1279 return -EFAULT; 1280 if (offset_in_page(a.offset)) 1281 return -EINVAL; 1282 1283 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1284 a.offset >> PAGE_SHIFT); 1285 } 1286 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1287 1288 /* 1289 * split a vma into two pieces at address 'addr', a new vma is allocated either 1290 * for the first part or the tail. 1291 */ 1292 static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, 1293 unsigned long addr, int new_below) 1294 { 1295 struct vm_area_struct *new; 1296 struct vm_region *region; 1297 unsigned long npages; 1298 struct mm_struct *mm; 1299 1300 /* we're only permitted to split anonymous regions (these should have 1301 * only a single usage on the region) */ 1302 if (vma->vm_file) 1303 return -ENOMEM; 1304 1305 mm = vma->vm_mm; 1306 if (mm->map_count >= sysctl_max_map_count) 1307 return -ENOMEM; 1308 1309 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); 1310 if (!region) 1311 return -ENOMEM; 1312 1313 new = vm_area_dup(vma); 1314 if (!new) 1315 goto err_vma_dup; 1316 1317 /* most fields are the same, copy all, and then fixup */ 1318 *region = *vma->vm_region; 1319 new->vm_region = region; 1320 1321 npages = (addr - vma->vm_start) >> PAGE_SHIFT; 1322 1323 if (new_below) { 1324 region->vm_top = region->vm_end = new->vm_end = addr; 1325 } else { 1326 region->vm_start = new->vm_start = addr; 1327 region->vm_pgoff = new->vm_pgoff += npages; 1328 } 1329 1330 vma_iter_config(vmi, new->vm_start, new->vm_end); 1331 if (vma_iter_prealloc(vmi, vma)) { 1332 pr_warn("Allocation of vma tree for process %d failed\n", 1333 current->pid); 1334 goto err_vmi_preallocate; 1335 } 1336 1337 if (new->vm_ops && new->vm_ops->open) 1338 new->vm_ops->open(new); 1339 1340 down_write(&nommu_region_sem); 1341 delete_nommu_region(vma->vm_region); 1342 if (new_below) { 1343 vma->vm_region->vm_start = vma->vm_start = addr; 1344 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; 1345 } else { 1346 vma->vm_region->vm_end = vma->vm_end = addr; 1347 vma->vm_region->vm_top = addr; 1348 } 1349 add_nommu_region(vma->vm_region); 1350 add_nommu_region(new->vm_region); 1351 up_write(&nommu_region_sem); 1352 1353 setup_vma_to_mm(vma, mm); 1354 setup_vma_to_mm(new, mm); 1355 vma_iter_store(vmi, new); 1356 mm->map_count++; 1357 return 0; 1358 1359 err_vmi_preallocate: 1360 vm_area_free(new); 1361 err_vma_dup: 1362 kmem_cache_free(vm_region_jar, region); 1363 return -ENOMEM; 1364 } 1365 1366 /* 1367 * shrink a VMA by removing the specified chunk from either the beginning or 1368 * the end 1369 */ 1370 static int vmi_shrink_vma(struct vma_iterator *vmi, 1371 struct vm_area_struct *vma, 1372 unsigned long from, unsigned long to) 1373 { 1374 struct vm_region *region; 1375 1376 /* adjust the VMA's pointers, which may reposition it in the MM's tree 1377 * and list */ 1378 if (from > vma->vm_start) { 1379 if (vma_iter_clear_gfp(vmi, from, vma->vm_end, GFP_KERNEL)) 1380 return -ENOMEM; 1381 vma->vm_end = from; 1382 } else { 1383 if (vma_iter_clear_gfp(vmi, vma->vm_start, to, GFP_KERNEL)) 1384 return -ENOMEM; 1385 vma->vm_start = to; 1386 } 1387 1388 /* cut the backing region down to size */ 1389 region = vma->vm_region; 1390 BUG_ON(region->vm_usage != 1); 1391 1392 down_write(&nommu_region_sem); 1393 delete_nommu_region(region); 1394 if (from > region->vm_start) { 1395 to = region->vm_top; 1396 region->vm_top = region->vm_end = from; 1397 } else { 1398 region->vm_start = to; 1399 } 1400 add_nommu_region(region); 1401 up_write(&nommu_region_sem); 1402 1403 free_page_series(from, to); 1404 return 0; 1405 } 1406 1407 /* 1408 * release a mapping 1409 * - under NOMMU conditions the chunk to be unmapped must be backed by a single 1410 * VMA, though it need not cover the whole VMA 1411 */ 1412 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len, struct list_head *uf) 1413 { 1414 VMA_ITERATOR(vmi, mm, start); 1415 struct vm_area_struct *vma; 1416 unsigned long end; 1417 int ret = 0; 1418 1419 len = PAGE_ALIGN(len); 1420 if (len == 0) 1421 return -EINVAL; 1422 1423 end = start + len; 1424 1425 /* find the first potentially overlapping VMA */ 1426 vma = vma_find(&vmi, end); 1427 if (!vma) { 1428 static int limit; 1429 if (limit < 5) { 1430 pr_warn("munmap of memory not mmapped by process %d (%s): 0x%lx-0x%lx\n", 1431 current->pid, current->comm, 1432 start, start + len - 1); 1433 limit++; 1434 } 1435 return -EINVAL; 1436 } 1437 1438 /* we're allowed to split an anonymous VMA but not a file-backed one */ 1439 if (vma->vm_file) { 1440 do { 1441 if (start > vma->vm_start) 1442 return -EINVAL; 1443 if (end == vma->vm_end) 1444 goto erase_whole_vma; 1445 vma = vma_find(&vmi, end); 1446 } while (vma); 1447 return -EINVAL; 1448 } else { 1449 /* the chunk must be a subset of the VMA found */ 1450 if (start == vma->vm_start && end == vma->vm_end) 1451 goto erase_whole_vma; 1452 if (start < vma->vm_start || end > vma->vm_end) 1453 return -EINVAL; 1454 if (offset_in_page(start)) 1455 return -EINVAL; 1456 if (end != vma->vm_end && offset_in_page(end)) 1457 return -EINVAL; 1458 if (start != vma->vm_start && end != vma->vm_end) { 1459 ret = split_vma(&vmi, vma, start, 1); 1460 if (ret < 0) 1461 return ret; 1462 } 1463 return vmi_shrink_vma(&vmi, vma, start, end); 1464 } 1465 1466 erase_whole_vma: 1467 if (delete_vma_from_mm(vma)) 1468 ret = -ENOMEM; 1469 else 1470 delete_vma(mm, vma); 1471 return ret; 1472 } 1473 1474 int vm_munmap(unsigned long addr, size_t len) 1475 { 1476 struct mm_struct *mm = current->mm; 1477 int ret; 1478 1479 mmap_write_lock(mm); 1480 ret = do_munmap(mm, addr, len, NULL); 1481 mmap_write_unlock(mm); 1482 return ret; 1483 } 1484 EXPORT_SYMBOL(vm_munmap); 1485 1486 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1487 { 1488 return vm_munmap(addr, len); 1489 } 1490 1491 /* 1492 * release all the mappings made in a process's VM space 1493 */ 1494 void exit_mmap(struct mm_struct *mm) 1495 { 1496 VMA_ITERATOR(vmi, mm, 0); 1497 struct vm_area_struct *vma; 1498 1499 if (!mm) 1500 return; 1501 1502 mm->total_vm = 0; 1503 1504 /* 1505 * Lock the mm to avoid assert complaining even though this is the only 1506 * user of the mm 1507 */ 1508 mmap_write_lock(mm); 1509 for_each_vma(vmi, vma) { 1510 cleanup_vma_from_mm(vma); 1511 delete_vma(mm, vma); 1512 cond_resched(); 1513 } 1514 __mt_destroy(&mm->mm_mt); 1515 mmap_write_unlock(mm); 1516 } 1517 1518 /* 1519 * expand (or shrink) an existing mapping, potentially moving it at the same 1520 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1521 * 1522 * under NOMMU conditions, we only permit changing a mapping's size, and only 1523 * as long as it stays within the region allocated by do_mmap_private() and the 1524 * block is not shareable 1525 * 1526 * MREMAP_FIXED is not supported under NOMMU conditions 1527 */ 1528 static unsigned long do_mremap(unsigned long addr, 1529 unsigned long old_len, unsigned long new_len, 1530 unsigned long flags, unsigned long new_addr) 1531 { 1532 struct vm_area_struct *vma; 1533 1534 /* insanity checks first */ 1535 old_len = PAGE_ALIGN(old_len); 1536 new_len = PAGE_ALIGN(new_len); 1537 if (old_len == 0 || new_len == 0) 1538 return (unsigned long) -EINVAL; 1539 1540 if (offset_in_page(addr)) 1541 return -EINVAL; 1542 1543 if (flags & MREMAP_FIXED && new_addr != addr) 1544 return (unsigned long) -EINVAL; 1545 1546 vma = find_vma_exact(current->mm, addr, old_len); 1547 if (!vma) 1548 return (unsigned long) -EINVAL; 1549 1550 if (vma->vm_end != vma->vm_start + old_len) 1551 return (unsigned long) -EFAULT; 1552 1553 if (is_nommu_shared_mapping(vma->vm_flags)) 1554 return (unsigned long) -EPERM; 1555 1556 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) 1557 return (unsigned long) -ENOMEM; 1558 1559 /* all checks complete - do it */ 1560 vma->vm_end = vma->vm_start + new_len; 1561 return vma->vm_start; 1562 } 1563 1564 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, 1565 unsigned long, new_len, unsigned long, flags, 1566 unsigned long, new_addr) 1567 { 1568 unsigned long ret; 1569 1570 mmap_write_lock(current->mm); 1571 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1572 mmap_write_unlock(current->mm); 1573 return ret; 1574 } 1575 1576 struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1577 unsigned int foll_flags) 1578 { 1579 return NULL; 1580 } 1581 1582 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1583 unsigned long pfn, unsigned long size, pgprot_t prot) 1584 { 1585 if (addr != (pfn << PAGE_SHIFT)) 1586 return -EINVAL; 1587 1588 vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP); 1589 return 0; 1590 } 1591 EXPORT_SYMBOL(remap_pfn_range); 1592 1593 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len) 1594 { 1595 unsigned long pfn = start >> PAGE_SHIFT; 1596 unsigned long vm_len = vma->vm_end - vma->vm_start; 1597 1598 pfn += vma->vm_pgoff; 1599 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot); 1600 } 1601 EXPORT_SYMBOL(vm_iomap_memory); 1602 1603 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 1604 unsigned long pgoff) 1605 { 1606 unsigned int size = vma->vm_end - vma->vm_start; 1607 1608 if (!(vma->vm_flags & VM_USERMAP)) 1609 return -EINVAL; 1610 1611 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); 1612 vma->vm_end = vma->vm_start + size; 1613 1614 return 0; 1615 } 1616 EXPORT_SYMBOL(remap_vmalloc_range); 1617 1618 vm_fault_t filemap_fault(struct vm_fault *vmf) 1619 { 1620 BUG(); 1621 return 0; 1622 } 1623 EXPORT_SYMBOL(filemap_fault); 1624 1625 vm_fault_t filemap_map_pages(struct vm_fault *vmf, 1626 pgoff_t start_pgoff, pgoff_t end_pgoff) 1627 { 1628 BUG(); 1629 return 0; 1630 } 1631 EXPORT_SYMBOL(filemap_map_pages); 1632 1633 static int __access_remote_vm(struct mm_struct *mm, unsigned long addr, 1634 void *buf, int len, unsigned int gup_flags) 1635 { 1636 struct vm_area_struct *vma; 1637 int write = gup_flags & FOLL_WRITE; 1638 1639 if (mmap_read_lock_killable(mm)) 1640 return 0; 1641 1642 /* the access must start within one of the target process's mappings */ 1643 vma = find_vma(mm, addr); 1644 if (vma) { 1645 /* don't overrun this mapping */ 1646 if (addr + len >= vma->vm_end) 1647 len = vma->vm_end - addr; 1648 1649 /* only read or write mappings where it is permitted */ 1650 if (write && vma->vm_flags & VM_MAYWRITE) 1651 copy_to_user_page(vma, NULL, addr, 1652 (void *) addr, buf, len); 1653 else if (!write && vma->vm_flags & VM_MAYREAD) 1654 copy_from_user_page(vma, NULL, addr, 1655 buf, (void *) addr, len); 1656 else 1657 len = 0; 1658 } else { 1659 len = 0; 1660 } 1661 1662 mmap_read_unlock(mm); 1663 1664 return len; 1665 } 1666 1667 /** 1668 * access_remote_vm - access another process' address space 1669 * @mm: the mm_struct of the target address space 1670 * @addr: start address to access 1671 * @buf: source or destination buffer 1672 * @len: number of bytes to transfer 1673 * @gup_flags: flags modifying lookup behaviour 1674 * 1675 * The caller must hold a reference on @mm. 1676 */ 1677 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 1678 void *buf, int len, unsigned int gup_flags) 1679 { 1680 return __access_remote_vm(mm, addr, buf, len, gup_flags); 1681 } 1682 1683 /* 1684 * Access another process' address space. 1685 * - source/target buffer must be kernel space 1686 */ 1687 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, 1688 unsigned int gup_flags) 1689 { 1690 struct mm_struct *mm; 1691 1692 if (addr + len < addr) 1693 return 0; 1694 1695 mm = get_task_mm(tsk); 1696 if (!mm) 1697 return 0; 1698 1699 len = __access_remote_vm(mm, addr, buf, len, gup_flags); 1700 1701 mmput(mm); 1702 return len; 1703 } 1704 EXPORT_SYMBOL_GPL(access_process_vm); 1705 1706 /** 1707 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode 1708 * @inode: The inode to check 1709 * @size: The current filesize of the inode 1710 * @newsize: The proposed filesize of the inode 1711 * 1712 * Check the shared mappings on an inode on behalf of a shrinking truncate to 1713 * make sure that any outstanding VMAs aren't broken and then shrink the 1714 * vm_regions that extend beyond so that do_mmap() doesn't 1715 * automatically grant mappings that are too large. 1716 */ 1717 int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 1718 size_t newsize) 1719 { 1720 struct vm_area_struct *vma; 1721 struct vm_region *region; 1722 pgoff_t low, high; 1723 size_t r_size, r_top; 1724 1725 low = newsize >> PAGE_SHIFT; 1726 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 1727 1728 down_write(&nommu_region_sem); 1729 i_mmap_lock_read(inode->i_mapping); 1730 1731 /* search for VMAs that fall within the dead zone */ 1732 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { 1733 /* found one - only interested if it's shared out of the page 1734 * cache */ 1735 if (vma->vm_flags & VM_SHARED) { 1736 i_mmap_unlock_read(inode->i_mapping); 1737 up_write(&nommu_region_sem); 1738 return -ETXTBSY; /* not quite true, but near enough */ 1739 } 1740 } 1741 1742 /* reduce any regions that overlap the dead zone - if in existence, 1743 * these will be pointed to by VMAs that don't overlap the dead zone 1744 * 1745 * we don't check for any regions that start beyond the EOF as there 1746 * shouldn't be any 1747 */ 1748 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) { 1749 if (!(vma->vm_flags & VM_SHARED)) 1750 continue; 1751 1752 region = vma->vm_region; 1753 r_size = region->vm_top - region->vm_start; 1754 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; 1755 1756 if (r_top > newsize) { 1757 region->vm_top -= r_top - newsize; 1758 if (region->vm_end > region->vm_top) 1759 region->vm_end = region->vm_top; 1760 } 1761 } 1762 1763 i_mmap_unlock_read(inode->i_mapping); 1764 up_write(&nommu_region_sem); 1765 return 0; 1766 } 1767 1768 /* 1769 * Initialise sysctl_user_reserve_kbytes. 1770 * 1771 * This is intended to prevent a user from starting a single memory hogging 1772 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER 1773 * mode. 1774 * 1775 * The default value is min(3% of free memory, 128MB) 1776 * 128MB is enough to recover with sshd/login, bash, and top/kill. 1777 */ 1778 static int __meminit init_user_reserve(void) 1779 { 1780 unsigned long free_kbytes; 1781 1782 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); 1783 1784 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17); 1785 return 0; 1786 } 1787 subsys_initcall(init_user_reserve); 1788 1789 /* 1790 * Initialise sysctl_admin_reserve_kbytes. 1791 * 1792 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin 1793 * to log in and kill a memory hogging process. 1794 * 1795 * Systems with more than 256MB will reserve 8MB, enough to recover 1796 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will 1797 * only reserve 3% of free pages by default. 1798 */ 1799 static int __meminit init_admin_reserve(void) 1800 { 1801 unsigned long free_kbytes; 1802 1803 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES)); 1804 1805 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13); 1806 return 0; 1807 } 1808 subsys_initcall(init_admin_reserve); 1809