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