1 /* 2 * linux/mm/nommu.c 3 * 4 * Replacement code for mm functions to support CPU's that don't 5 * have any form of memory management unit (thus no virtual memory). 6 * 7 * See Documentation/nommu-mmap.txt 8 * 9 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com> 10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com> 11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org> 12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com> 13 * Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org> 14 */ 15 16 #include <linux/module.h> 17 #include <linux/mm.h> 18 #include <linux/mman.h> 19 #include <linux/swap.h> 20 #include <linux/file.h> 21 #include <linux/highmem.h> 22 #include <linux/pagemap.h> 23 #include <linux/slab.h> 24 #include <linux/vmalloc.h> 25 #include <linux/tracehook.h> 26 #include <linux/blkdev.h> 27 #include <linux/backing-dev.h> 28 #include <linux/mount.h> 29 #include <linux/personality.h> 30 #include <linux/security.h> 31 #include <linux/syscalls.h> 32 #include <linux/audit.h> 33 34 #include <asm/uaccess.h> 35 #include <asm/tlb.h> 36 #include <asm/tlbflush.h> 37 #include <asm/mmu_context.h> 38 #include "internal.h" 39 40 #if 0 41 #define kenter(FMT, ...) \ 42 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 43 #define kleave(FMT, ...) \ 44 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 45 #define kdebug(FMT, ...) \ 46 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__) 47 #else 48 #define kenter(FMT, ...) \ 49 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 50 #define kleave(FMT, ...) \ 51 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 52 #define kdebug(FMT, ...) \ 53 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__) 54 #endif 55 56 void *high_memory; 57 struct page *mem_map; 58 unsigned long max_mapnr; 59 unsigned long num_physpages; 60 unsigned long highest_memmap_pfn; 61 struct percpu_counter vm_committed_as; 62 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 63 int sysctl_overcommit_ratio = 50; /* default is 50% */ 64 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 65 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; 66 int heap_stack_gap = 0; 67 68 atomic_long_t mmap_pages_allocated; 69 70 EXPORT_SYMBOL(mem_map); 71 EXPORT_SYMBOL(num_physpages); 72 73 /* list of mapped, potentially shareable regions */ 74 static struct kmem_cache *vm_region_jar; 75 struct rb_root nommu_region_tree = RB_ROOT; 76 DECLARE_RWSEM(nommu_region_sem); 77 78 const struct vm_operations_struct generic_file_vm_ops = { 79 }; 80 81 /* 82 * Return the total memory allocated for this pointer, not 83 * just what the caller asked for. 84 * 85 * Doesn't have to be accurate, i.e. may have races. 86 */ 87 unsigned int kobjsize(const void *objp) 88 { 89 struct page *page; 90 91 /* 92 * If the object we have should not have ksize performed on it, 93 * return size of 0 94 */ 95 if (!objp || !virt_addr_valid(objp)) 96 return 0; 97 98 page = virt_to_head_page(objp); 99 100 /* 101 * If the allocator sets PageSlab, we know the pointer came from 102 * kmalloc(). 103 */ 104 if (PageSlab(page)) 105 return ksize(objp); 106 107 /* 108 * If it's not a compound page, see if we have a matching VMA 109 * region. This test is intentionally done in reverse order, 110 * so if there's no VMA, we still fall through and hand back 111 * PAGE_SIZE for 0-order pages. 112 */ 113 if (!PageCompound(page)) { 114 struct vm_area_struct *vma; 115 116 vma = find_vma(current->mm, (unsigned long)objp); 117 if (vma) 118 return vma->vm_end - vma->vm_start; 119 } 120 121 /* 122 * The ksize() function is only guaranteed to work for pointers 123 * returned by kmalloc(). So handle arbitrary pointers here. 124 */ 125 return PAGE_SIZE << compound_order(page); 126 } 127 128 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 129 unsigned long start, int nr_pages, unsigned int foll_flags, 130 struct page **pages, struct vm_area_struct **vmas) 131 { 132 struct vm_area_struct *vma; 133 unsigned long vm_flags; 134 int i; 135 136 /* calculate required read or write permissions. 137 * If FOLL_FORCE is set, we only require the "MAY" flags. 138 */ 139 vm_flags = (foll_flags & FOLL_WRITE) ? 140 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 141 vm_flags &= (foll_flags & FOLL_FORCE) ? 142 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 143 144 for (i = 0; i < nr_pages; i++) { 145 vma = find_vma(mm, start); 146 if (!vma) 147 goto finish_or_fault; 148 149 /* protect what we can, including chardevs */ 150 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || 151 !(vm_flags & vma->vm_flags)) 152 goto finish_or_fault; 153 154 if (pages) { 155 pages[i] = virt_to_page(start); 156 if (pages[i]) 157 page_cache_get(pages[i]); 158 } 159 if (vmas) 160 vmas[i] = vma; 161 start = (start + PAGE_SIZE) & PAGE_MASK; 162 } 163 164 return i; 165 166 finish_or_fault: 167 return i ? : -EFAULT; 168 } 169 170 /* 171 * get a list of pages in an address range belonging to the specified process 172 * and indicate the VMA that covers each page 173 * - this is potentially dodgy as we may end incrementing the page count of a 174 * slab page or a secondary page from a compound page 175 * - don't permit access to VMAs that don't support it, such as I/O mappings 176 */ 177 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 178 unsigned long start, int nr_pages, int write, int force, 179 struct page **pages, struct vm_area_struct **vmas) 180 { 181 int flags = 0; 182 183 if (write) 184 flags |= FOLL_WRITE; 185 if (force) 186 flags |= FOLL_FORCE; 187 188 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas); 189 } 190 EXPORT_SYMBOL(get_user_pages); 191 192 /** 193 * follow_pfn - look up PFN at a user virtual address 194 * @vma: memory mapping 195 * @address: user virtual address 196 * @pfn: location to store found PFN 197 * 198 * Only IO mappings and raw PFN mappings are allowed. 199 * 200 * Returns zero and the pfn at @pfn on success, -ve otherwise. 201 */ 202 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 203 unsigned long *pfn) 204 { 205 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 206 return -EINVAL; 207 208 *pfn = address >> PAGE_SHIFT; 209 return 0; 210 } 211 EXPORT_SYMBOL(follow_pfn); 212 213 DEFINE_RWLOCK(vmlist_lock); 214 struct vm_struct *vmlist; 215 216 void vfree(const void *addr) 217 { 218 kfree(addr); 219 } 220 EXPORT_SYMBOL(vfree); 221 222 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 223 { 224 /* 225 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() 226 * returns only a logical address. 227 */ 228 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 229 } 230 EXPORT_SYMBOL(__vmalloc); 231 232 void *vmalloc_user(unsigned long size) 233 { 234 void *ret; 235 236 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 237 PAGE_KERNEL); 238 if (ret) { 239 struct vm_area_struct *vma; 240 241 down_write(¤t->mm->mmap_sem); 242 vma = find_vma(current->mm, (unsigned long)ret); 243 if (vma) 244 vma->vm_flags |= VM_USERMAP; 245 up_write(¤t->mm->mmap_sem); 246 } 247 248 return ret; 249 } 250 EXPORT_SYMBOL(vmalloc_user); 251 252 struct page *vmalloc_to_page(const void *addr) 253 { 254 return virt_to_page(addr); 255 } 256 EXPORT_SYMBOL(vmalloc_to_page); 257 258 unsigned long vmalloc_to_pfn(const void *addr) 259 { 260 return page_to_pfn(virt_to_page(addr)); 261 } 262 EXPORT_SYMBOL(vmalloc_to_pfn); 263 264 long vread(char *buf, char *addr, unsigned long count) 265 { 266 memcpy(buf, addr, count); 267 return count; 268 } 269 270 long vwrite(char *buf, char *addr, unsigned long count) 271 { 272 /* Don't allow overflow */ 273 if ((unsigned long) addr + count < count) 274 count = -(unsigned long) addr; 275 276 memcpy(addr, buf, count); 277 return(count); 278 } 279 280 /* 281 * vmalloc - allocate virtually continguos memory 282 * 283 * @size: allocation size 284 * 285 * Allocate enough pages to cover @size from the page level 286 * allocator and map them into continguos kernel virtual space. 287 * 288 * For tight control over page level allocator and protection flags 289 * use __vmalloc() instead. 290 */ 291 void *vmalloc(unsigned long size) 292 { 293 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 294 } 295 EXPORT_SYMBOL(vmalloc); 296 297 /* 298 * vzalloc - allocate virtually continguos memory with zero fill 299 * 300 * @size: allocation size 301 * 302 * Allocate enough pages to cover @size from the page level 303 * allocator and map them into continguos kernel virtual space. 304 * The memory allocated is set to zero. 305 * 306 * For tight control over page level allocator and protection flags 307 * use __vmalloc() instead. 308 */ 309 void *vzalloc(unsigned long size) 310 { 311 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 312 PAGE_KERNEL); 313 } 314 EXPORT_SYMBOL(vzalloc); 315 316 /** 317 * vmalloc_node - allocate memory on a specific node 318 * @size: allocation size 319 * @node: numa node 320 * 321 * Allocate enough pages to cover @size from the page level 322 * allocator and map them into contiguous kernel virtual space. 323 * 324 * For tight control over page level allocator and protection flags 325 * use __vmalloc() instead. 326 */ 327 void *vmalloc_node(unsigned long size, int node) 328 { 329 return vmalloc(size); 330 } 331 332 /** 333 * vzalloc_node - allocate memory on a specific node with zero fill 334 * @size: allocation size 335 * @node: numa node 336 * 337 * Allocate enough pages to cover @size from the page level 338 * allocator and map them into contiguous kernel virtual space. 339 * The memory allocated is set to zero. 340 * 341 * For tight control over page level allocator and protection flags 342 * use __vmalloc() instead. 343 */ 344 void *vzalloc_node(unsigned long size, int node) 345 { 346 return vzalloc(size); 347 } 348 EXPORT_SYMBOL(vzalloc_node); 349 350 #ifndef PAGE_KERNEL_EXEC 351 # define PAGE_KERNEL_EXEC PAGE_KERNEL 352 #endif 353 354 /** 355 * vmalloc_exec - allocate virtually contiguous, executable memory 356 * @size: allocation size 357 * 358 * Kernel-internal function to allocate enough pages to cover @size 359 * the page level allocator and map them into contiguous and 360 * executable kernel virtual space. 361 * 362 * For tight control over page level allocator and protection flags 363 * use __vmalloc() instead. 364 */ 365 366 void *vmalloc_exec(unsigned long size) 367 { 368 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); 369 } 370 371 /** 372 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) 373 * @size: allocation size 374 * 375 * Allocate enough 32bit PA addressable pages to cover @size from the 376 * page level allocator and map them into continguos kernel virtual space. 377 */ 378 void *vmalloc_32(unsigned long size) 379 { 380 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 381 } 382 EXPORT_SYMBOL(vmalloc_32); 383 384 /** 385 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory 386 * @size: allocation size 387 * 388 * The resulting memory area is 32bit addressable and zeroed so it can be 389 * mapped to userspace without leaking data. 390 * 391 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to 392 * remap_vmalloc_range() are permissible. 393 */ 394 void *vmalloc_32_user(unsigned long size) 395 { 396 /* 397 * We'll have to sort out the ZONE_DMA bits for 64-bit, 398 * but for now this can simply use vmalloc_user() directly. 399 */ 400 return vmalloc_user(size); 401 } 402 EXPORT_SYMBOL(vmalloc_32_user); 403 404 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 405 { 406 BUG(); 407 return NULL; 408 } 409 EXPORT_SYMBOL(vmap); 410 411 void vunmap(const void *addr) 412 { 413 BUG(); 414 } 415 EXPORT_SYMBOL(vunmap); 416 417 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) 418 { 419 BUG(); 420 return NULL; 421 } 422 EXPORT_SYMBOL(vm_map_ram); 423 424 void vm_unmap_ram(const void *mem, unsigned int count) 425 { 426 BUG(); 427 } 428 EXPORT_SYMBOL(vm_unmap_ram); 429 430 void vm_unmap_aliases(void) 431 { 432 } 433 EXPORT_SYMBOL_GPL(vm_unmap_aliases); 434 435 /* 436 * Implement a stub for vmalloc_sync_all() if the architecture chose not to 437 * have one. 438 */ 439 void __attribute__((weak)) vmalloc_sync_all(void) 440 { 441 } 442 443 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 444 struct page *page) 445 { 446 return -EINVAL; 447 } 448 EXPORT_SYMBOL(vm_insert_page); 449 450 /* 451 * sys_brk() for the most part doesn't need the global kernel 452 * lock, except when an application is doing something nasty 453 * like trying to un-brk an area that has already been mapped 454 * to a regular file. in this case, the unmapping will need 455 * to invoke file system routines that need the global lock. 456 */ 457 SYSCALL_DEFINE1(brk, unsigned long, brk) 458 { 459 struct mm_struct *mm = current->mm; 460 461 if (brk < mm->start_brk || brk > mm->context.end_brk) 462 return mm->brk; 463 464 if (mm->brk == brk) 465 return mm->brk; 466 467 /* 468 * Always allow shrinking brk 469 */ 470 if (brk <= mm->brk) { 471 mm->brk = brk; 472 return brk; 473 } 474 475 /* 476 * Ok, looks good - let it rip. 477 */ 478 flush_icache_range(mm->brk, brk); 479 return mm->brk = brk; 480 } 481 482 /* 483 * initialise the VMA and region record slabs 484 */ 485 void __init mmap_init(void) 486 { 487 int ret; 488 489 ret = percpu_counter_init(&vm_committed_as, 0); 490 VM_BUG_ON(ret); 491 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC); 492 } 493 494 /* 495 * validate the region tree 496 * - the caller must hold the region lock 497 */ 498 #ifdef CONFIG_DEBUG_NOMMU_REGIONS 499 static noinline void validate_nommu_regions(void) 500 { 501 struct vm_region *region, *last; 502 struct rb_node *p, *lastp; 503 504 lastp = rb_first(&nommu_region_tree); 505 if (!lastp) 506 return; 507 508 last = rb_entry(lastp, struct vm_region, vm_rb); 509 BUG_ON(unlikely(last->vm_end <= last->vm_start)); 510 BUG_ON(unlikely(last->vm_top < last->vm_end)); 511 512 while ((p = rb_next(lastp))) { 513 region = rb_entry(p, struct vm_region, vm_rb); 514 last = rb_entry(lastp, struct vm_region, vm_rb); 515 516 BUG_ON(unlikely(region->vm_end <= region->vm_start)); 517 BUG_ON(unlikely(region->vm_top < region->vm_end)); 518 BUG_ON(unlikely(region->vm_start < last->vm_top)); 519 520 lastp = p; 521 } 522 } 523 #else 524 static void validate_nommu_regions(void) 525 { 526 } 527 #endif 528 529 /* 530 * add a region into the global tree 531 */ 532 static void add_nommu_region(struct vm_region *region) 533 { 534 struct vm_region *pregion; 535 struct rb_node **p, *parent; 536 537 validate_nommu_regions(); 538 539 parent = NULL; 540 p = &nommu_region_tree.rb_node; 541 while (*p) { 542 parent = *p; 543 pregion = rb_entry(parent, struct vm_region, vm_rb); 544 if (region->vm_start < pregion->vm_start) 545 p = &(*p)->rb_left; 546 else if (region->vm_start > pregion->vm_start) 547 p = &(*p)->rb_right; 548 else if (pregion == region) 549 return; 550 else 551 BUG(); 552 } 553 554 rb_link_node(®ion->vm_rb, parent, p); 555 rb_insert_color(®ion->vm_rb, &nommu_region_tree); 556 557 validate_nommu_regions(); 558 } 559 560 /* 561 * delete a region from the global tree 562 */ 563 static void delete_nommu_region(struct vm_region *region) 564 { 565 BUG_ON(!nommu_region_tree.rb_node); 566 567 validate_nommu_regions(); 568 rb_erase(®ion->vm_rb, &nommu_region_tree); 569 validate_nommu_regions(); 570 } 571 572 /* 573 * free a contiguous series of pages 574 */ 575 static void free_page_series(unsigned long from, unsigned long to) 576 { 577 for (; from < to; from += PAGE_SIZE) { 578 struct page *page = virt_to_page(from); 579 580 kdebug("- free %lx", from); 581 atomic_long_dec(&mmap_pages_allocated); 582 if (page_count(page) != 1) 583 kdebug("free page %p: refcount not one: %d", 584 page, page_count(page)); 585 put_page(page); 586 } 587 } 588 589 /* 590 * release a reference to a region 591 * - the caller must hold the region semaphore for writing, which this releases 592 * - the region may not have been added to the tree yet, in which case vm_top 593 * will equal vm_start 594 */ 595 static void __put_nommu_region(struct vm_region *region) 596 __releases(nommu_region_sem) 597 { 598 kenter("%p{%d}", region, region->vm_usage); 599 600 BUG_ON(!nommu_region_tree.rb_node); 601 602 if (--region->vm_usage == 0) { 603 if (region->vm_top > region->vm_start) 604 delete_nommu_region(region); 605 up_write(&nommu_region_sem); 606 607 if (region->vm_file) 608 fput(region->vm_file); 609 610 /* IO memory and memory shared directly out of the pagecache 611 * from ramfs/tmpfs mustn't be released here */ 612 if (region->vm_flags & VM_MAPPED_COPY) { 613 kdebug("free series"); 614 free_page_series(region->vm_start, region->vm_top); 615 } 616 kmem_cache_free(vm_region_jar, region); 617 } else { 618 up_write(&nommu_region_sem); 619 } 620 } 621 622 /* 623 * release a reference to a region 624 */ 625 static void put_nommu_region(struct vm_region *region) 626 { 627 down_write(&nommu_region_sem); 628 __put_nommu_region(region); 629 } 630 631 /* 632 * update protection on a vma 633 */ 634 static void protect_vma(struct vm_area_struct *vma, unsigned long flags) 635 { 636 #ifdef CONFIG_MPU 637 struct mm_struct *mm = vma->vm_mm; 638 long start = vma->vm_start & PAGE_MASK; 639 while (start < vma->vm_end) { 640 protect_page(mm, start, flags); 641 start += PAGE_SIZE; 642 } 643 update_protections(mm); 644 #endif 645 } 646 647 /* 648 * add a VMA into a process's mm_struct in the appropriate place in the list 649 * and tree and add to the address space's page tree also if not an anonymous 650 * page 651 * - should be called with mm->mmap_sem held writelocked 652 */ 653 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) 654 { 655 struct vm_area_struct *pvma, **pp, *next; 656 struct address_space *mapping; 657 struct rb_node **p, *parent; 658 659 kenter(",%p", vma); 660 661 BUG_ON(!vma->vm_region); 662 663 mm->map_count++; 664 vma->vm_mm = mm; 665 666 protect_vma(vma, vma->vm_flags); 667 668 /* add the VMA to the mapping */ 669 if (vma->vm_file) { 670 mapping = vma->vm_file->f_mapping; 671 672 flush_dcache_mmap_lock(mapping); 673 vma_prio_tree_insert(vma, &mapping->i_mmap); 674 flush_dcache_mmap_unlock(mapping); 675 } 676 677 /* add the VMA to the tree */ 678 parent = NULL; 679 p = &mm->mm_rb.rb_node; 680 while (*p) { 681 parent = *p; 682 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 683 684 /* sort by: start addr, end addr, VMA struct addr in that order 685 * (the latter is necessary as we may get identical VMAs) */ 686 if (vma->vm_start < pvma->vm_start) 687 p = &(*p)->rb_left; 688 else if (vma->vm_start > pvma->vm_start) 689 p = &(*p)->rb_right; 690 else if (vma->vm_end < pvma->vm_end) 691 p = &(*p)->rb_left; 692 else if (vma->vm_end > pvma->vm_end) 693 p = &(*p)->rb_right; 694 else if (vma < pvma) 695 p = &(*p)->rb_left; 696 else if (vma > pvma) 697 p = &(*p)->rb_right; 698 else 699 BUG(); 700 } 701 702 rb_link_node(&vma->vm_rb, parent, p); 703 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 704 705 /* add VMA to the VMA list also */ 706 for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) { 707 if (pvma->vm_start > vma->vm_start) 708 break; 709 if (pvma->vm_start < vma->vm_start) 710 continue; 711 if (pvma->vm_end < vma->vm_end) 712 break; 713 } 714 715 next = *pp; 716 *pp = vma; 717 vma->vm_next = next; 718 if (next) 719 next->vm_prev = vma; 720 } 721 722 /* 723 * delete a VMA from its owning mm_struct and address space 724 */ 725 static void delete_vma_from_mm(struct vm_area_struct *vma) 726 { 727 struct vm_area_struct **pp; 728 struct address_space *mapping; 729 struct mm_struct *mm = vma->vm_mm; 730 731 kenter("%p", vma); 732 733 protect_vma(vma, 0); 734 735 mm->map_count--; 736 if (mm->mmap_cache == vma) 737 mm->mmap_cache = NULL; 738 739 /* remove the VMA from the mapping */ 740 if (vma->vm_file) { 741 mapping = vma->vm_file->f_mapping; 742 743 flush_dcache_mmap_lock(mapping); 744 vma_prio_tree_remove(vma, &mapping->i_mmap); 745 flush_dcache_mmap_unlock(mapping); 746 } 747 748 /* remove from the MM's tree and list */ 749 rb_erase(&vma->vm_rb, &mm->mm_rb); 750 for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) { 751 if (*pp == vma) { 752 *pp = vma->vm_next; 753 break; 754 } 755 } 756 757 vma->vm_mm = NULL; 758 } 759 760 /* 761 * destroy a VMA record 762 */ 763 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) 764 { 765 kenter("%p", vma); 766 if (vma->vm_ops && vma->vm_ops->close) 767 vma->vm_ops->close(vma); 768 if (vma->vm_file) { 769 fput(vma->vm_file); 770 if (vma->vm_flags & VM_EXECUTABLE) 771 removed_exe_file_vma(mm); 772 } 773 put_nommu_region(vma->vm_region); 774 kmem_cache_free(vm_area_cachep, vma); 775 } 776 777 /* 778 * look up the first VMA in which addr resides, NULL if none 779 * - should be called with mm->mmap_sem at least held readlocked 780 */ 781 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 782 { 783 struct vm_area_struct *vma; 784 struct rb_node *n = mm->mm_rb.rb_node; 785 786 /* check the cache first */ 787 vma = mm->mmap_cache; 788 if (vma && vma->vm_start <= addr && vma->vm_end > addr) 789 return vma; 790 791 /* trawl the tree (there may be multiple mappings in which addr 792 * resides) */ 793 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) { 794 vma = rb_entry(n, struct vm_area_struct, vm_rb); 795 if (vma->vm_start > addr) 796 return NULL; 797 if (vma->vm_end > addr) { 798 mm->mmap_cache = vma; 799 return vma; 800 } 801 } 802 803 return NULL; 804 } 805 EXPORT_SYMBOL(find_vma); 806 807 /* 808 * find a VMA 809 * - we don't extend stack VMAs under NOMMU conditions 810 */ 811 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 812 { 813 return find_vma(mm, addr); 814 } 815 816 /* 817 * expand a stack to a given address 818 * - not supported under NOMMU conditions 819 */ 820 int expand_stack(struct vm_area_struct *vma, unsigned long address) 821 { 822 return -ENOMEM; 823 } 824 825 /* 826 * look up the first VMA exactly that exactly matches addr 827 * - should be called with mm->mmap_sem at least held readlocked 828 */ 829 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 830 unsigned long addr, 831 unsigned long len) 832 { 833 struct vm_area_struct *vma; 834 struct rb_node *n = mm->mm_rb.rb_node; 835 unsigned long end = addr + len; 836 837 /* check the cache first */ 838 vma = mm->mmap_cache; 839 if (vma && vma->vm_start == addr && vma->vm_end == end) 840 return vma; 841 842 /* trawl the tree (there may be multiple mappings in which addr 843 * resides) */ 844 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) { 845 vma = rb_entry(n, struct vm_area_struct, vm_rb); 846 if (vma->vm_start < addr) 847 continue; 848 if (vma->vm_start > addr) 849 return NULL; 850 if (vma->vm_end == end) { 851 mm->mmap_cache = vma; 852 return vma; 853 } 854 } 855 856 return NULL; 857 } 858 859 /* 860 * determine whether a mapping should be permitted and, if so, what sort of 861 * mapping we're capable of supporting 862 */ 863 static int validate_mmap_request(struct file *file, 864 unsigned long addr, 865 unsigned long len, 866 unsigned long prot, 867 unsigned long flags, 868 unsigned long pgoff, 869 unsigned long *_capabilities) 870 { 871 unsigned long capabilities, rlen; 872 unsigned long reqprot = prot; 873 int ret; 874 875 /* do the simple checks first */ 876 if (flags & MAP_FIXED) { 877 printk(KERN_DEBUG 878 "%d: Can't do fixed-address/overlay mmap of RAM\n", 879 current->pid); 880 return -EINVAL; 881 } 882 883 if ((flags & MAP_TYPE) != MAP_PRIVATE && 884 (flags & MAP_TYPE) != MAP_SHARED) 885 return -EINVAL; 886 887 if (!len) 888 return -EINVAL; 889 890 /* Careful about overflows.. */ 891 rlen = PAGE_ALIGN(len); 892 if (!rlen || rlen > TASK_SIZE) 893 return -ENOMEM; 894 895 /* offset overflow? */ 896 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) 897 return -EOVERFLOW; 898 899 if (file) { 900 /* validate file mapping requests */ 901 struct address_space *mapping; 902 903 /* files must support mmap */ 904 if (!file->f_op || !file->f_op->mmap) 905 return -ENODEV; 906 907 /* work out if what we've got could possibly be shared 908 * - we support chardevs that provide their own "memory" 909 * - we support files/blockdevs that are memory backed 910 */ 911 mapping = file->f_mapping; 912 if (!mapping) 913 mapping = file->f_path.dentry->d_inode->i_mapping; 914 915 capabilities = 0; 916 if (mapping && mapping->backing_dev_info) 917 capabilities = mapping->backing_dev_info->capabilities; 918 919 if (!capabilities) { 920 /* no explicit capabilities set, so assume some 921 * defaults */ 922 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) { 923 case S_IFREG: 924 case S_IFBLK: 925 capabilities = BDI_CAP_MAP_COPY; 926 break; 927 928 case S_IFCHR: 929 capabilities = 930 BDI_CAP_MAP_DIRECT | 931 BDI_CAP_READ_MAP | 932 BDI_CAP_WRITE_MAP; 933 break; 934 935 default: 936 return -EINVAL; 937 } 938 } 939 940 /* eliminate any capabilities that we can't support on this 941 * device */ 942 if (!file->f_op->get_unmapped_area) 943 capabilities &= ~BDI_CAP_MAP_DIRECT; 944 if (!file->f_op->read) 945 capabilities &= ~BDI_CAP_MAP_COPY; 946 947 /* The file shall have been opened with read permission. */ 948 if (!(file->f_mode & FMODE_READ)) 949 return -EACCES; 950 951 if (flags & MAP_SHARED) { 952 /* do checks for writing, appending and locking */ 953 if ((prot & PROT_WRITE) && 954 !(file->f_mode & FMODE_WRITE)) 955 return -EACCES; 956 957 if (IS_APPEND(file->f_path.dentry->d_inode) && 958 (file->f_mode & FMODE_WRITE)) 959 return -EACCES; 960 961 if (locks_verify_locked(file->f_path.dentry->d_inode)) 962 return -EAGAIN; 963 964 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 965 return -ENODEV; 966 967 /* we mustn't privatise shared mappings */ 968 capabilities &= ~BDI_CAP_MAP_COPY; 969 } 970 else { 971 /* we're going to read the file into private memory we 972 * allocate */ 973 if (!(capabilities & BDI_CAP_MAP_COPY)) 974 return -ENODEV; 975 976 /* we don't permit a private writable mapping to be 977 * shared with the backing device */ 978 if (prot & PROT_WRITE) 979 capabilities &= ~BDI_CAP_MAP_DIRECT; 980 } 981 982 if (capabilities & BDI_CAP_MAP_DIRECT) { 983 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 984 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 985 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 986 ) { 987 capabilities &= ~BDI_CAP_MAP_DIRECT; 988 if (flags & MAP_SHARED) { 989 printk(KERN_WARNING 990 "MAP_SHARED not completely supported on !MMU\n"); 991 return -EINVAL; 992 } 993 } 994 } 995 996 /* handle executable mappings and implied executable 997 * mappings */ 998 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 999 if (prot & PROT_EXEC) 1000 return -EPERM; 1001 } 1002 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 1003 /* handle implication of PROT_EXEC by PROT_READ */ 1004 if (current->personality & READ_IMPLIES_EXEC) { 1005 if (capabilities & BDI_CAP_EXEC_MAP) 1006 prot |= PROT_EXEC; 1007 } 1008 } 1009 else if ((prot & PROT_READ) && 1010 (prot & PROT_EXEC) && 1011 !(capabilities & BDI_CAP_EXEC_MAP) 1012 ) { 1013 /* backing file is not executable, try to copy */ 1014 capabilities &= ~BDI_CAP_MAP_DIRECT; 1015 } 1016 } 1017 else { 1018 /* anonymous mappings are always memory backed and can be 1019 * privately mapped 1020 */ 1021 capabilities = BDI_CAP_MAP_COPY; 1022 1023 /* handle PROT_EXEC implication by PROT_READ */ 1024 if ((prot & PROT_READ) && 1025 (current->personality & READ_IMPLIES_EXEC)) 1026 prot |= PROT_EXEC; 1027 } 1028 1029 /* allow the security API to have its say */ 1030 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1031 if (ret < 0) 1032 return ret; 1033 1034 /* looks okay */ 1035 *_capabilities = capabilities; 1036 return 0; 1037 } 1038 1039 /* 1040 * we've determined that we can make the mapping, now translate what we 1041 * now know into VMA flags 1042 */ 1043 static unsigned long determine_vm_flags(struct file *file, 1044 unsigned long prot, 1045 unsigned long flags, 1046 unsigned long capabilities) 1047 { 1048 unsigned long vm_flags; 1049 1050 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 1051 /* vm_flags |= mm->def_flags; */ 1052 1053 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 1054 /* attempt to share read-only copies of mapped file chunks */ 1055 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1056 if (file && !(prot & PROT_WRITE)) 1057 vm_flags |= VM_MAYSHARE; 1058 } else { 1059 /* overlay a shareable mapping on the backing device or inode 1060 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 1061 * romfs/cramfs */ 1062 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS); 1063 if (flags & MAP_SHARED) 1064 vm_flags |= VM_SHARED; 1065 } 1066 1067 /* refuse to let anyone share private mappings with this process if 1068 * it's being traced - otherwise breakpoints set in it may interfere 1069 * with another untraced process 1070 */ 1071 if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current)) 1072 vm_flags &= ~VM_MAYSHARE; 1073 1074 return vm_flags; 1075 } 1076 1077 /* 1078 * set up a shared mapping on a file (the driver or filesystem provides and 1079 * pins the storage) 1080 */ 1081 static int do_mmap_shared_file(struct vm_area_struct *vma) 1082 { 1083 int ret; 1084 1085 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1086 if (ret == 0) { 1087 vma->vm_region->vm_top = vma->vm_region->vm_end; 1088 return 0; 1089 } 1090 if (ret != -ENOSYS) 1091 return ret; 1092 1093 /* getting -ENOSYS indicates that direct mmap isn't possible (as 1094 * opposed to tried but failed) so we can only give a suitable error as 1095 * it's not possible to make a private copy if MAP_SHARED was given */ 1096 return -ENODEV; 1097 } 1098 1099 /* 1100 * set up a private mapping or an anonymous shared mapping 1101 */ 1102 static int do_mmap_private(struct vm_area_struct *vma, 1103 struct vm_region *region, 1104 unsigned long len, 1105 unsigned long capabilities) 1106 { 1107 struct page *pages; 1108 unsigned long total, point, n, rlen; 1109 void *base; 1110 int ret, order; 1111 1112 /* invoke the file's mapping function so that it can keep track of 1113 * shared mappings on devices or memory 1114 * - VM_MAYSHARE will be set if it may attempt to share 1115 */ 1116 if (capabilities & BDI_CAP_MAP_DIRECT) { 1117 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1118 if (ret == 0) { 1119 /* shouldn't return success if we're not sharing */ 1120 BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); 1121 vma->vm_region->vm_top = vma->vm_region->vm_end; 1122 return 0; 1123 } 1124 if (ret != -ENOSYS) 1125 return ret; 1126 1127 /* getting an ENOSYS error indicates that direct mmap isn't 1128 * possible (as opposed to tried but failed) so we'll try to 1129 * make a private copy of the data and map that instead */ 1130 } 1131 1132 rlen = PAGE_ALIGN(len); 1133 1134 /* allocate some memory to hold the mapping 1135 * - note that this may not return a page-aligned address if the object 1136 * we're allocating is smaller than a page 1137 */ 1138 order = get_order(rlen); 1139 kdebug("alloc order %d for %lx", order, len); 1140 1141 pages = alloc_pages(GFP_KERNEL, order); 1142 if (!pages) 1143 goto enomem; 1144 1145 total = 1 << order; 1146 atomic_long_add(total, &mmap_pages_allocated); 1147 1148 point = rlen >> PAGE_SHIFT; 1149 1150 /* we allocated a power-of-2 sized page set, so we may want to trim off 1151 * the excess */ 1152 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) { 1153 while (total > point) { 1154 order = ilog2(total - point); 1155 n = 1 << order; 1156 kdebug("shave %lu/%lu @%lu", n, total - point, total); 1157 atomic_long_sub(n, &mmap_pages_allocated); 1158 total -= n; 1159 set_page_refcounted(pages + total); 1160 __free_pages(pages + total, order); 1161 } 1162 } 1163 1164 for (point = 1; point < total; point++) 1165 set_page_refcounted(&pages[point]); 1166 1167 base = page_address(pages); 1168 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; 1169 region->vm_start = (unsigned long) base; 1170 region->vm_end = region->vm_start + rlen; 1171 region->vm_top = region->vm_start + (total << PAGE_SHIFT); 1172 1173 vma->vm_start = region->vm_start; 1174 vma->vm_end = region->vm_start + len; 1175 1176 if (vma->vm_file) { 1177 /* read the contents of a file into the copy */ 1178 mm_segment_t old_fs; 1179 loff_t fpos; 1180 1181 fpos = vma->vm_pgoff; 1182 fpos <<= PAGE_SHIFT; 1183 1184 old_fs = get_fs(); 1185 set_fs(KERNEL_DS); 1186 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos); 1187 set_fs(old_fs); 1188 1189 if (ret < 0) 1190 goto error_free; 1191 1192 /* clear the last little bit */ 1193 if (ret < rlen) 1194 memset(base + ret, 0, rlen - ret); 1195 1196 } 1197 1198 return 0; 1199 1200 error_free: 1201 free_page_series(region->vm_start, region->vm_end); 1202 region->vm_start = vma->vm_start = 0; 1203 region->vm_end = vma->vm_end = 0; 1204 region->vm_top = 0; 1205 return ret; 1206 1207 enomem: 1208 printk("Allocation of length %lu from process %d (%s) failed\n", 1209 len, current->pid, current->comm); 1210 show_free_areas(); 1211 return -ENOMEM; 1212 } 1213 1214 /* 1215 * handle mapping creation for uClinux 1216 */ 1217 unsigned long do_mmap_pgoff(struct file *file, 1218 unsigned long addr, 1219 unsigned long len, 1220 unsigned long prot, 1221 unsigned long flags, 1222 unsigned long pgoff) 1223 { 1224 struct vm_area_struct *vma; 1225 struct vm_region *region; 1226 struct rb_node *rb; 1227 unsigned long capabilities, vm_flags, result; 1228 int ret; 1229 1230 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff); 1231 1232 /* decide whether we should attempt the mapping, and if so what sort of 1233 * mapping */ 1234 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 1235 &capabilities); 1236 if (ret < 0) { 1237 kleave(" = %d [val]", ret); 1238 return ret; 1239 } 1240 1241 /* we ignore the address hint */ 1242 addr = 0; 1243 1244 /* we've determined that we can make the mapping, now translate what we 1245 * now know into VMA flags */ 1246 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 1247 1248 /* we're going to need to record the mapping */ 1249 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); 1250 if (!region) 1251 goto error_getting_region; 1252 1253 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1254 if (!vma) 1255 goto error_getting_vma; 1256 1257 region->vm_usage = 1; 1258 region->vm_flags = vm_flags; 1259 region->vm_pgoff = pgoff; 1260 1261 INIT_LIST_HEAD(&vma->anon_vma_chain); 1262 vma->vm_flags = vm_flags; 1263 vma->vm_pgoff = pgoff; 1264 1265 if (file) { 1266 region->vm_file = file; 1267 get_file(file); 1268 vma->vm_file = file; 1269 get_file(file); 1270 if (vm_flags & VM_EXECUTABLE) { 1271 added_exe_file_vma(current->mm); 1272 vma->vm_mm = current->mm; 1273 } 1274 } 1275 1276 down_write(&nommu_region_sem); 1277 1278 /* if we want to share, we need to check for regions created by other 1279 * mmap() calls that overlap with our proposed mapping 1280 * - we can only share with a superset match on most regular files 1281 * - shared mappings on character devices and memory backed files are 1282 * permitted to overlap inexactly as far as we are concerned for in 1283 * these cases, sharing is handled in the driver or filesystem rather 1284 * than here 1285 */ 1286 if (vm_flags & VM_MAYSHARE) { 1287 struct vm_region *pregion; 1288 unsigned long pglen, rpglen, pgend, rpgend, start; 1289 1290 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1291 pgend = pgoff + pglen; 1292 1293 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { 1294 pregion = rb_entry(rb, struct vm_region, vm_rb); 1295 1296 if (!(pregion->vm_flags & VM_MAYSHARE)) 1297 continue; 1298 1299 /* search for overlapping mappings on the same file */ 1300 if (pregion->vm_file->f_path.dentry->d_inode != 1301 file->f_path.dentry->d_inode) 1302 continue; 1303 1304 if (pregion->vm_pgoff >= pgend) 1305 continue; 1306 1307 rpglen = pregion->vm_end - pregion->vm_start; 1308 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1309 rpgend = pregion->vm_pgoff + rpglen; 1310 if (pgoff >= rpgend) 1311 continue; 1312 1313 /* handle inexactly overlapping matches between 1314 * mappings */ 1315 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && 1316 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { 1317 /* new mapping is not a subset of the region */ 1318 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 1319 goto sharing_violation; 1320 continue; 1321 } 1322 1323 /* we've found a region we can share */ 1324 pregion->vm_usage++; 1325 vma->vm_region = pregion; 1326 start = pregion->vm_start; 1327 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; 1328 vma->vm_start = start; 1329 vma->vm_end = start + len; 1330 1331 if (pregion->vm_flags & VM_MAPPED_COPY) { 1332 kdebug("share copy"); 1333 vma->vm_flags |= VM_MAPPED_COPY; 1334 } else { 1335 kdebug("share mmap"); 1336 ret = do_mmap_shared_file(vma); 1337 if (ret < 0) { 1338 vma->vm_region = NULL; 1339 vma->vm_start = 0; 1340 vma->vm_end = 0; 1341 pregion->vm_usage--; 1342 pregion = NULL; 1343 goto error_just_free; 1344 } 1345 } 1346 fput(region->vm_file); 1347 kmem_cache_free(vm_region_jar, region); 1348 region = pregion; 1349 result = start; 1350 goto share; 1351 } 1352 1353 /* obtain the address at which to make a shared mapping 1354 * - this is the hook for quasi-memory character devices to 1355 * tell us the location of a shared mapping 1356 */ 1357 if (capabilities & BDI_CAP_MAP_DIRECT) { 1358 addr = file->f_op->get_unmapped_area(file, addr, len, 1359 pgoff, flags); 1360 if (IS_ERR((void *) addr)) { 1361 ret = addr; 1362 if (ret != (unsigned long) -ENOSYS) 1363 goto error_just_free; 1364 1365 /* the driver refused to tell us where to site 1366 * the mapping so we'll have to attempt to copy 1367 * it */ 1368 ret = (unsigned long) -ENODEV; 1369 if (!(capabilities & BDI_CAP_MAP_COPY)) 1370 goto error_just_free; 1371 1372 capabilities &= ~BDI_CAP_MAP_DIRECT; 1373 } else { 1374 vma->vm_start = region->vm_start = addr; 1375 vma->vm_end = region->vm_end = addr + len; 1376 } 1377 } 1378 } 1379 1380 vma->vm_region = region; 1381 1382 /* set up the mapping 1383 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set 1384 */ 1385 if (file && vma->vm_flags & VM_SHARED) 1386 ret = do_mmap_shared_file(vma); 1387 else 1388 ret = do_mmap_private(vma, region, len, capabilities); 1389 if (ret < 0) 1390 goto error_just_free; 1391 add_nommu_region(region); 1392 1393 /* clear anonymous mappings that don't ask for uninitialized data */ 1394 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) 1395 memset((void *)region->vm_start, 0, 1396 region->vm_end - region->vm_start); 1397 1398 /* okay... we have a mapping; now we have to register it */ 1399 result = vma->vm_start; 1400 1401 current->mm->total_vm += len >> PAGE_SHIFT; 1402 1403 share: 1404 add_vma_to_mm(current->mm, vma); 1405 1406 /* we flush the region from the icache only when the first executable 1407 * mapping of it is made */ 1408 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { 1409 flush_icache_range(region->vm_start, region->vm_end); 1410 region->vm_icache_flushed = true; 1411 } 1412 1413 up_write(&nommu_region_sem); 1414 1415 kleave(" = %lx", result); 1416 return result; 1417 1418 error_just_free: 1419 up_write(&nommu_region_sem); 1420 error: 1421 if (region->vm_file) 1422 fput(region->vm_file); 1423 kmem_cache_free(vm_region_jar, region); 1424 if (vma->vm_file) 1425 fput(vma->vm_file); 1426 if (vma->vm_flags & VM_EXECUTABLE) 1427 removed_exe_file_vma(vma->vm_mm); 1428 kmem_cache_free(vm_area_cachep, vma); 1429 kleave(" = %d", ret); 1430 return ret; 1431 1432 sharing_violation: 1433 up_write(&nommu_region_sem); 1434 printk(KERN_WARNING "Attempt to share mismatched mappings\n"); 1435 ret = -EINVAL; 1436 goto error; 1437 1438 error_getting_vma: 1439 kmem_cache_free(vm_region_jar, region); 1440 printk(KERN_WARNING "Allocation of vma for %lu byte allocation" 1441 " from process %d failed\n", 1442 len, current->pid); 1443 show_free_areas(); 1444 return -ENOMEM; 1445 1446 error_getting_region: 1447 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation" 1448 " from process %d failed\n", 1449 len, current->pid); 1450 show_free_areas(); 1451 return -ENOMEM; 1452 } 1453 EXPORT_SYMBOL(do_mmap_pgoff); 1454 1455 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1456 unsigned long, prot, unsigned long, flags, 1457 unsigned long, fd, unsigned long, pgoff) 1458 { 1459 struct file *file = NULL; 1460 unsigned long retval = -EBADF; 1461 1462 audit_mmap_fd(fd, flags); 1463 if (!(flags & MAP_ANONYMOUS)) { 1464 file = fget(fd); 1465 if (!file) 1466 goto out; 1467 } 1468 1469 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1470 1471 down_write(¤t->mm->mmap_sem); 1472 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1473 up_write(¤t->mm->mmap_sem); 1474 1475 if (file) 1476 fput(file); 1477 out: 1478 return retval; 1479 } 1480 1481 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1482 struct mmap_arg_struct { 1483 unsigned long addr; 1484 unsigned long len; 1485 unsigned long prot; 1486 unsigned long flags; 1487 unsigned long fd; 1488 unsigned long offset; 1489 }; 1490 1491 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1492 { 1493 struct mmap_arg_struct a; 1494 1495 if (copy_from_user(&a, arg, sizeof(a))) 1496 return -EFAULT; 1497 if (a.offset & ~PAGE_MASK) 1498 return -EINVAL; 1499 1500 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1501 a.offset >> PAGE_SHIFT); 1502 } 1503 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1504 1505 /* 1506 * split a vma into two pieces at address 'addr', a new vma is allocated either 1507 * for the first part or the tail. 1508 */ 1509 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 1510 unsigned long addr, int new_below) 1511 { 1512 struct vm_area_struct *new; 1513 struct vm_region *region; 1514 unsigned long npages; 1515 1516 kenter(""); 1517 1518 /* we're only permitted to split anonymous regions (these should have 1519 * only a single usage on the region) */ 1520 if (vma->vm_file) 1521 return -ENOMEM; 1522 1523 if (mm->map_count >= sysctl_max_map_count) 1524 return -ENOMEM; 1525 1526 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); 1527 if (!region) 1528 return -ENOMEM; 1529 1530 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1531 if (!new) { 1532 kmem_cache_free(vm_region_jar, region); 1533 return -ENOMEM; 1534 } 1535 1536 /* most fields are the same, copy all, and then fixup */ 1537 *new = *vma; 1538 *region = *vma->vm_region; 1539 new->vm_region = region; 1540 1541 npages = (addr - vma->vm_start) >> PAGE_SHIFT; 1542 1543 if (new_below) { 1544 region->vm_top = region->vm_end = new->vm_end = addr; 1545 } else { 1546 region->vm_start = new->vm_start = addr; 1547 region->vm_pgoff = new->vm_pgoff += npages; 1548 } 1549 1550 if (new->vm_ops && new->vm_ops->open) 1551 new->vm_ops->open(new); 1552 1553 delete_vma_from_mm(vma); 1554 down_write(&nommu_region_sem); 1555 delete_nommu_region(vma->vm_region); 1556 if (new_below) { 1557 vma->vm_region->vm_start = vma->vm_start = addr; 1558 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; 1559 } else { 1560 vma->vm_region->vm_end = vma->vm_end = addr; 1561 vma->vm_region->vm_top = addr; 1562 } 1563 add_nommu_region(vma->vm_region); 1564 add_nommu_region(new->vm_region); 1565 up_write(&nommu_region_sem); 1566 add_vma_to_mm(mm, vma); 1567 add_vma_to_mm(mm, new); 1568 return 0; 1569 } 1570 1571 /* 1572 * shrink a VMA by removing the specified chunk from either the beginning or 1573 * the end 1574 */ 1575 static int shrink_vma(struct mm_struct *mm, 1576 struct vm_area_struct *vma, 1577 unsigned long from, unsigned long to) 1578 { 1579 struct vm_region *region; 1580 1581 kenter(""); 1582 1583 /* adjust the VMA's pointers, which may reposition it in the MM's tree 1584 * and list */ 1585 delete_vma_from_mm(vma); 1586 if (from > vma->vm_start) 1587 vma->vm_end = from; 1588 else 1589 vma->vm_start = to; 1590 add_vma_to_mm(mm, vma); 1591 1592 /* cut the backing region down to size */ 1593 region = vma->vm_region; 1594 BUG_ON(region->vm_usage != 1); 1595 1596 down_write(&nommu_region_sem); 1597 delete_nommu_region(region); 1598 if (from > region->vm_start) { 1599 to = region->vm_top; 1600 region->vm_top = region->vm_end = from; 1601 } else { 1602 region->vm_start = to; 1603 } 1604 add_nommu_region(region); 1605 up_write(&nommu_region_sem); 1606 1607 free_page_series(from, to); 1608 return 0; 1609 } 1610 1611 /* 1612 * release a mapping 1613 * - under NOMMU conditions the chunk to be unmapped must be backed by a single 1614 * VMA, though it need not cover the whole VMA 1615 */ 1616 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1617 { 1618 struct vm_area_struct *vma; 1619 struct rb_node *rb; 1620 unsigned long end = start + len; 1621 int ret; 1622 1623 kenter(",%lx,%zx", start, len); 1624 1625 if (len == 0) 1626 return -EINVAL; 1627 1628 /* find the first potentially overlapping VMA */ 1629 vma = find_vma(mm, start); 1630 if (!vma) { 1631 static int limit = 0; 1632 if (limit < 5) { 1633 printk(KERN_WARNING 1634 "munmap of memory not mmapped by process %d" 1635 " (%s): 0x%lx-0x%lx\n", 1636 current->pid, current->comm, 1637 start, start + len - 1); 1638 limit++; 1639 } 1640 return -EINVAL; 1641 } 1642 1643 /* we're allowed to split an anonymous VMA but not a file-backed one */ 1644 if (vma->vm_file) { 1645 do { 1646 if (start > vma->vm_start) { 1647 kleave(" = -EINVAL [miss]"); 1648 return -EINVAL; 1649 } 1650 if (end == vma->vm_end) 1651 goto erase_whole_vma; 1652 rb = rb_next(&vma->vm_rb); 1653 vma = rb_entry(rb, struct vm_area_struct, vm_rb); 1654 } while (rb); 1655 kleave(" = -EINVAL [split file]"); 1656 return -EINVAL; 1657 } else { 1658 /* the chunk must be a subset of the VMA found */ 1659 if (start == vma->vm_start && end == vma->vm_end) 1660 goto erase_whole_vma; 1661 if (start < vma->vm_start || end > vma->vm_end) { 1662 kleave(" = -EINVAL [superset]"); 1663 return -EINVAL; 1664 } 1665 if (start & ~PAGE_MASK) { 1666 kleave(" = -EINVAL [unaligned start]"); 1667 return -EINVAL; 1668 } 1669 if (end != vma->vm_end && end & ~PAGE_MASK) { 1670 kleave(" = -EINVAL [unaligned split]"); 1671 return -EINVAL; 1672 } 1673 if (start != vma->vm_start && end != vma->vm_end) { 1674 ret = split_vma(mm, vma, start, 1); 1675 if (ret < 0) { 1676 kleave(" = %d [split]", ret); 1677 return ret; 1678 } 1679 } 1680 return shrink_vma(mm, vma, start, end); 1681 } 1682 1683 erase_whole_vma: 1684 delete_vma_from_mm(vma); 1685 delete_vma(mm, vma); 1686 kleave(" = 0"); 1687 return 0; 1688 } 1689 EXPORT_SYMBOL(do_munmap); 1690 1691 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1692 { 1693 int ret; 1694 struct mm_struct *mm = current->mm; 1695 1696 down_write(&mm->mmap_sem); 1697 ret = do_munmap(mm, addr, len); 1698 up_write(&mm->mmap_sem); 1699 return ret; 1700 } 1701 1702 /* 1703 * release all the mappings made in a process's VM space 1704 */ 1705 void exit_mmap(struct mm_struct *mm) 1706 { 1707 struct vm_area_struct *vma; 1708 1709 if (!mm) 1710 return; 1711 1712 kenter(""); 1713 1714 mm->total_vm = 0; 1715 1716 while ((vma = mm->mmap)) { 1717 mm->mmap = vma->vm_next; 1718 delete_vma_from_mm(vma); 1719 delete_vma(mm, vma); 1720 } 1721 1722 kleave(""); 1723 } 1724 1725 unsigned long do_brk(unsigned long addr, unsigned long len) 1726 { 1727 return -ENOMEM; 1728 } 1729 1730 /* 1731 * expand (or shrink) an existing mapping, potentially moving it at the same 1732 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1733 * 1734 * under NOMMU conditions, we only permit changing a mapping's size, and only 1735 * as long as it stays within the region allocated by do_mmap_private() and the 1736 * block is not shareable 1737 * 1738 * MREMAP_FIXED is not supported under NOMMU conditions 1739 */ 1740 unsigned long do_mremap(unsigned long addr, 1741 unsigned long old_len, unsigned long new_len, 1742 unsigned long flags, unsigned long new_addr) 1743 { 1744 struct vm_area_struct *vma; 1745 1746 /* insanity checks first */ 1747 if (old_len == 0 || new_len == 0) 1748 return (unsigned long) -EINVAL; 1749 1750 if (addr & ~PAGE_MASK) 1751 return -EINVAL; 1752 1753 if (flags & MREMAP_FIXED && new_addr != addr) 1754 return (unsigned long) -EINVAL; 1755 1756 vma = find_vma_exact(current->mm, addr, old_len); 1757 if (!vma) 1758 return (unsigned long) -EINVAL; 1759 1760 if (vma->vm_end != vma->vm_start + old_len) 1761 return (unsigned long) -EFAULT; 1762 1763 if (vma->vm_flags & VM_MAYSHARE) 1764 return (unsigned long) -EPERM; 1765 1766 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) 1767 return (unsigned long) -ENOMEM; 1768 1769 /* all checks complete - do it */ 1770 vma->vm_end = vma->vm_start + new_len; 1771 return vma->vm_start; 1772 } 1773 EXPORT_SYMBOL(do_mremap); 1774 1775 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, 1776 unsigned long, new_len, unsigned long, flags, 1777 unsigned long, new_addr) 1778 { 1779 unsigned long ret; 1780 1781 down_write(¤t->mm->mmap_sem); 1782 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1783 up_write(¤t->mm->mmap_sem); 1784 return ret; 1785 } 1786 1787 struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1788 unsigned int foll_flags) 1789 { 1790 return NULL; 1791 } 1792 1793 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 1794 unsigned long to, unsigned long size, pgprot_t prot) 1795 { 1796 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT; 1797 return 0; 1798 } 1799 EXPORT_SYMBOL(remap_pfn_range); 1800 1801 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 1802 unsigned long pgoff) 1803 { 1804 unsigned int size = vma->vm_end - vma->vm_start; 1805 1806 if (!(vma->vm_flags & VM_USERMAP)) 1807 return -EINVAL; 1808 1809 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); 1810 vma->vm_end = vma->vm_start + size; 1811 1812 return 0; 1813 } 1814 EXPORT_SYMBOL(remap_vmalloc_range); 1815 1816 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) 1817 { 1818 } 1819 1820 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1821 unsigned long len, unsigned long pgoff, unsigned long flags) 1822 { 1823 return -ENOMEM; 1824 } 1825 1826 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1827 { 1828 } 1829 1830 void unmap_mapping_range(struct address_space *mapping, 1831 loff_t const holebegin, loff_t const holelen, 1832 int even_cows) 1833 { 1834 } 1835 EXPORT_SYMBOL(unmap_mapping_range); 1836 1837 /* 1838 * Check that a process has enough memory to allocate a new virtual 1839 * mapping. 0 means there is enough memory for the allocation to 1840 * succeed and -ENOMEM implies there is not. 1841 * 1842 * We currently support three overcommit policies, which are set via the 1843 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1844 * 1845 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1846 * Additional code 2002 Jul 20 by Robert Love. 1847 * 1848 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1849 * 1850 * Note this is a helper function intended to be used by LSMs which 1851 * wish to use this logic. 1852 */ 1853 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 1854 { 1855 unsigned long free, allowed; 1856 1857 vm_acct_memory(pages); 1858 1859 /* 1860 * Sometimes we want to use more memory than we have 1861 */ 1862 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1863 return 0; 1864 1865 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1866 unsigned long n; 1867 1868 free = global_page_state(NR_FILE_PAGES); 1869 free += nr_swap_pages; 1870 1871 /* 1872 * Any slabs which are created with the 1873 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1874 * which are reclaimable, under pressure. The dentry 1875 * cache and most inode caches should fall into this 1876 */ 1877 free += global_page_state(NR_SLAB_RECLAIMABLE); 1878 1879 /* 1880 * Leave the last 3% for root 1881 */ 1882 if (!cap_sys_admin) 1883 free -= free / 32; 1884 1885 if (free > pages) 1886 return 0; 1887 1888 /* 1889 * nr_free_pages() is very expensive on large systems, 1890 * only call if we're about to fail. 1891 */ 1892 n = nr_free_pages(); 1893 1894 /* 1895 * Leave reserved pages. The pages are not for anonymous pages. 1896 */ 1897 if (n <= totalreserve_pages) 1898 goto error; 1899 else 1900 n -= totalreserve_pages; 1901 1902 /* 1903 * Leave the last 3% for root 1904 */ 1905 if (!cap_sys_admin) 1906 n -= n / 32; 1907 free += n; 1908 1909 if (free > pages) 1910 return 0; 1911 1912 goto error; 1913 } 1914 1915 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1916 /* 1917 * Leave the last 3% for root 1918 */ 1919 if (!cap_sys_admin) 1920 allowed -= allowed / 32; 1921 allowed += total_swap_pages; 1922 1923 /* Don't let a single process grow too big: 1924 leave 3% of the size of this process for other processes */ 1925 if (mm) 1926 allowed -= mm->total_vm / 32; 1927 1928 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 1929 return 0; 1930 1931 error: 1932 vm_unacct_memory(pages); 1933 1934 return -ENOMEM; 1935 } 1936 1937 int in_gate_area_no_task(unsigned long addr) 1938 { 1939 return 0; 1940 } 1941 1942 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1943 { 1944 BUG(); 1945 return 0; 1946 } 1947 EXPORT_SYMBOL(filemap_fault); 1948 1949 /* 1950 * Access another process' address space. 1951 * - source/target buffer must be kernel space 1952 */ 1953 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 1954 { 1955 struct vm_area_struct *vma; 1956 struct mm_struct *mm; 1957 1958 if (addr + len < addr) 1959 return 0; 1960 1961 mm = get_task_mm(tsk); 1962 if (!mm) 1963 return 0; 1964 1965 down_read(&mm->mmap_sem); 1966 1967 /* the access must start within one of the target process's mappings */ 1968 vma = find_vma(mm, addr); 1969 if (vma) { 1970 /* don't overrun this mapping */ 1971 if (addr + len >= vma->vm_end) 1972 len = vma->vm_end - addr; 1973 1974 /* only read or write mappings where it is permitted */ 1975 if (write && vma->vm_flags & VM_MAYWRITE) 1976 copy_to_user_page(vma, NULL, addr, 1977 (void *) addr, buf, len); 1978 else if (!write && vma->vm_flags & VM_MAYREAD) 1979 copy_from_user_page(vma, NULL, addr, 1980 buf, (void *) addr, len); 1981 else 1982 len = 0; 1983 } else { 1984 len = 0; 1985 } 1986 1987 up_read(&mm->mmap_sem); 1988 mmput(mm); 1989 return len; 1990 } 1991 1992 /** 1993 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode 1994 * @inode: The inode to check 1995 * @size: The current filesize of the inode 1996 * @newsize: The proposed filesize of the inode 1997 * 1998 * Check the shared mappings on an inode on behalf of a shrinking truncate to 1999 * make sure that that any outstanding VMAs aren't broken and then shrink the 2000 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't 2001 * automatically grant mappings that are too large. 2002 */ 2003 int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 2004 size_t newsize) 2005 { 2006 struct vm_area_struct *vma; 2007 struct prio_tree_iter iter; 2008 struct vm_region *region; 2009 pgoff_t low, high; 2010 size_t r_size, r_top; 2011 2012 low = newsize >> PAGE_SHIFT; 2013 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 2014 2015 down_write(&nommu_region_sem); 2016 2017 /* search for VMAs that fall within the dead zone */ 2018 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap, 2019 low, high) { 2020 /* found one - only interested if it's shared out of the page 2021 * cache */ 2022 if (vma->vm_flags & VM_SHARED) { 2023 up_write(&nommu_region_sem); 2024 return -ETXTBSY; /* not quite true, but near enough */ 2025 } 2026 } 2027 2028 /* reduce any regions that overlap the dead zone - if in existence, 2029 * these will be pointed to by VMAs that don't overlap the dead zone 2030 * 2031 * we don't check for any regions that start beyond the EOF as there 2032 * shouldn't be any 2033 */ 2034 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap, 2035 0, ULONG_MAX) { 2036 if (!(vma->vm_flags & VM_SHARED)) 2037 continue; 2038 2039 region = vma->vm_region; 2040 r_size = region->vm_top - region->vm_start; 2041 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; 2042 2043 if (r_top > newsize) { 2044 region->vm_top -= r_top - newsize; 2045 if (region->vm_end > region->vm_top) 2046 region->vm_end = region->vm_top; 2047 } 2048 } 2049 2050 up_write(&nommu_region_sem); 2051 return 0; 2052 } 2053