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) 2007-2010 Paul Mundt <lethal@linux-sh.org> 14 */ 15 16 #include <linux/export.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/blkdev.h> 26 #include <linux/backing-dev.h> 27 #include <linux/mount.h> 28 #include <linux/personality.h> 29 #include <linux/security.h> 30 #include <linux/syscalls.h> 31 #include <linux/audit.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 #if 0 40 #define kenter(FMT, ...) \ 41 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 42 #define kleave(FMT, ...) \ 43 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 44 #define kdebug(FMT, ...) \ 45 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__) 46 #else 47 #define kenter(FMT, ...) \ 48 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 49 #define kleave(FMT, ...) \ 50 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 51 #define kdebug(FMT, ...) \ 52 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__) 53 #endif 54 55 void *high_memory; 56 struct page *mem_map; 57 unsigned long max_mapnr; 58 unsigned long num_physpages; 59 unsigned long highest_memmap_pfn; 60 struct percpu_counter vm_committed_as; 61 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 62 int sysctl_overcommit_ratio = 50; /* default is 50% */ 63 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 64 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; 65 int heap_stack_gap = 0; 66 67 atomic_long_t mmap_pages_allocated; 68 69 /* 70 * The global memory commitment made in the system can be a metric 71 * that can be used to drive ballooning decisions when Linux is hosted 72 * as a guest. On Hyper-V, the host implements a policy engine for dynamically 73 * balancing memory across competing virtual machines that are hosted. 74 * Several metrics drive this policy engine including the guest reported 75 * memory commitment. 76 */ 77 unsigned long vm_memory_committed(void) 78 { 79 return percpu_counter_read_positive(&vm_committed_as); 80 } 81 82 EXPORT_SYMBOL_GPL(vm_memory_committed); 83 84 EXPORT_SYMBOL(mem_map); 85 EXPORT_SYMBOL(num_physpages); 86 87 /* list of mapped, potentially shareable regions */ 88 static struct kmem_cache *vm_region_jar; 89 struct rb_root nommu_region_tree = RB_ROOT; 90 DECLARE_RWSEM(nommu_region_sem); 91 92 const struct vm_operations_struct generic_file_vm_ops = { 93 }; 94 95 /* 96 * Return the total memory allocated for this pointer, not 97 * just what the caller asked for. 98 * 99 * Doesn't have to be accurate, i.e. may have races. 100 */ 101 unsigned int kobjsize(const void *objp) 102 { 103 struct page *page; 104 105 /* 106 * If the object we have should not have ksize performed on it, 107 * return size of 0 108 */ 109 if (!objp || !virt_addr_valid(objp)) 110 return 0; 111 112 page = virt_to_head_page(objp); 113 114 /* 115 * If the allocator sets PageSlab, we know the pointer came from 116 * kmalloc(). 117 */ 118 if (PageSlab(page)) 119 return ksize(objp); 120 121 /* 122 * If it's not a compound page, see if we have a matching VMA 123 * region. This test is intentionally done in reverse order, 124 * so if there's no VMA, we still fall through and hand back 125 * PAGE_SIZE for 0-order pages. 126 */ 127 if (!PageCompound(page)) { 128 struct vm_area_struct *vma; 129 130 vma = find_vma(current->mm, (unsigned long)objp); 131 if (vma) 132 return vma->vm_end - vma->vm_start; 133 } 134 135 /* 136 * The ksize() function is only guaranteed to work for pointers 137 * returned by kmalloc(). So handle arbitrary pointers here. 138 */ 139 return PAGE_SIZE << compound_order(page); 140 } 141 142 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 143 unsigned long start, int nr_pages, unsigned int foll_flags, 144 struct page **pages, struct vm_area_struct **vmas, 145 int *retry) 146 { 147 struct vm_area_struct *vma; 148 unsigned long vm_flags; 149 int i; 150 151 /* calculate required read or write permissions. 152 * If FOLL_FORCE is set, we only require the "MAY" flags. 153 */ 154 vm_flags = (foll_flags & FOLL_WRITE) ? 155 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 156 vm_flags &= (foll_flags & FOLL_FORCE) ? 157 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 158 159 for (i = 0; i < nr_pages; i++) { 160 vma = find_vma(mm, start); 161 if (!vma) 162 goto finish_or_fault; 163 164 /* protect what we can, including chardevs */ 165 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || 166 !(vm_flags & vma->vm_flags)) 167 goto finish_or_fault; 168 169 if (pages) { 170 pages[i] = virt_to_page(start); 171 if (pages[i]) 172 page_cache_get(pages[i]); 173 } 174 if (vmas) 175 vmas[i] = vma; 176 start = (start + PAGE_SIZE) & PAGE_MASK; 177 } 178 179 return i; 180 181 finish_or_fault: 182 return i ? : -EFAULT; 183 } 184 185 /* 186 * get a list of pages in an address range belonging to the specified process 187 * and indicate the VMA that covers each page 188 * - this is potentially dodgy as we may end incrementing the page count of a 189 * slab page or a secondary page from a compound page 190 * - don't permit access to VMAs that don't support it, such as I/O mappings 191 */ 192 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 193 unsigned long start, int nr_pages, int write, int force, 194 struct page **pages, struct vm_area_struct **vmas) 195 { 196 int flags = 0; 197 198 if (write) 199 flags |= FOLL_WRITE; 200 if (force) 201 flags |= FOLL_FORCE; 202 203 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 204 NULL); 205 } 206 EXPORT_SYMBOL(get_user_pages); 207 208 /** 209 * follow_pfn - look up PFN at a user virtual address 210 * @vma: memory mapping 211 * @address: user virtual address 212 * @pfn: location to store found PFN 213 * 214 * Only IO mappings and raw PFN mappings are allowed. 215 * 216 * Returns zero and the pfn at @pfn on success, -ve otherwise. 217 */ 218 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 219 unsigned long *pfn) 220 { 221 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 222 return -EINVAL; 223 224 *pfn = address >> PAGE_SHIFT; 225 return 0; 226 } 227 EXPORT_SYMBOL(follow_pfn); 228 229 DEFINE_RWLOCK(vmlist_lock); 230 struct vm_struct *vmlist; 231 232 void vfree(const void *addr) 233 { 234 kfree(addr); 235 } 236 EXPORT_SYMBOL(vfree); 237 238 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 239 { 240 /* 241 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() 242 * returns only a logical address. 243 */ 244 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 245 } 246 EXPORT_SYMBOL(__vmalloc); 247 248 void *vmalloc_user(unsigned long size) 249 { 250 void *ret; 251 252 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 253 PAGE_KERNEL); 254 if (ret) { 255 struct vm_area_struct *vma; 256 257 down_write(¤t->mm->mmap_sem); 258 vma = find_vma(current->mm, (unsigned long)ret); 259 if (vma) 260 vma->vm_flags |= VM_USERMAP; 261 up_write(¤t->mm->mmap_sem); 262 } 263 264 return ret; 265 } 266 EXPORT_SYMBOL(vmalloc_user); 267 268 struct page *vmalloc_to_page(const void *addr) 269 { 270 return virt_to_page(addr); 271 } 272 EXPORT_SYMBOL(vmalloc_to_page); 273 274 unsigned long vmalloc_to_pfn(const void *addr) 275 { 276 return page_to_pfn(virt_to_page(addr)); 277 } 278 EXPORT_SYMBOL(vmalloc_to_pfn); 279 280 long vread(char *buf, char *addr, unsigned long count) 281 { 282 memcpy(buf, addr, count); 283 return count; 284 } 285 286 long vwrite(char *buf, char *addr, unsigned long count) 287 { 288 /* Don't allow overflow */ 289 if ((unsigned long) addr + count < count) 290 count = -(unsigned long) addr; 291 292 memcpy(addr, buf, count); 293 return(count); 294 } 295 296 /* 297 * vmalloc - allocate virtually continguos memory 298 * 299 * @size: allocation size 300 * 301 * Allocate enough pages to cover @size from the page level 302 * allocator and map them into continguos kernel virtual space. 303 * 304 * For tight control over page level allocator and protection flags 305 * use __vmalloc() instead. 306 */ 307 void *vmalloc(unsigned long size) 308 { 309 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 310 } 311 EXPORT_SYMBOL(vmalloc); 312 313 /* 314 * vzalloc - allocate virtually continguos memory with zero fill 315 * 316 * @size: allocation size 317 * 318 * Allocate enough pages to cover @size from the page level 319 * allocator and map them into continguos kernel virtual space. 320 * The memory allocated is set to zero. 321 * 322 * For tight control over page level allocator and protection flags 323 * use __vmalloc() instead. 324 */ 325 void *vzalloc(unsigned long size) 326 { 327 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 328 PAGE_KERNEL); 329 } 330 EXPORT_SYMBOL(vzalloc); 331 332 /** 333 * vmalloc_node - allocate memory on a specific node 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 * 340 * For tight control over page level allocator and protection flags 341 * use __vmalloc() instead. 342 */ 343 void *vmalloc_node(unsigned long size, int node) 344 { 345 return vmalloc(size); 346 } 347 EXPORT_SYMBOL(vmalloc_node); 348 349 /** 350 * vzalloc_node - allocate memory on a specific node with zero fill 351 * @size: allocation size 352 * @node: numa node 353 * 354 * Allocate enough pages to cover @size from the page level 355 * allocator and map them into contiguous kernel virtual space. 356 * The memory allocated is set to zero. 357 * 358 * For tight control over page level allocator and protection flags 359 * use __vmalloc() instead. 360 */ 361 void *vzalloc_node(unsigned long size, int node) 362 { 363 return vzalloc(size); 364 } 365 EXPORT_SYMBOL(vzalloc_node); 366 367 #ifndef PAGE_KERNEL_EXEC 368 # define PAGE_KERNEL_EXEC PAGE_KERNEL 369 #endif 370 371 /** 372 * vmalloc_exec - allocate virtually contiguous, executable memory 373 * @size: allocation size 374 * 375 * Kernel-internal function to allocate enough pages to cover @size 376 * the page level allocator and map them into contiguous and 377 * executable kernel virtual space. 378 * 379 * For tight control over page level allocator and protection flags 380 * use __vmalloc() instead. 381 */ 382 383 void *vmalloc_exec(unsigned long size) 384 { 385 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); 386 } 387 388 /** 389 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) 390 * @size: allocation size 391 * 392 * Allocate enough 32bit PA addressable pages to cover @size from the 393 * page level allocator and map them into continguos kernel virtual space. 394 */ 395 void *vmalloc_32(unsigned long size) 396 { 397 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 398 } 399 EXPORT_SYMBOL(vmalloc_32); 400 401 /** 402 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory 403 * @size: allocation size 404 * 405 * The resulting memory area is 32bit addressable and zeroed so it can be 406 * mapped to userspace without leaking data. 407 * 408 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to 409 * remap_vmalloc_range() are permissible. 410 */ 411 void *vmalloc_32_user(unsigned long size) 412 { 413 /* 414 * We'll have to sort out the ZONE_DMA bits for 64-bit, 415 * but for now this can simply use vmalloc_user() directly. 416 */ 417 return vmalloc_user(size); 418 } 419 EXPORT_SYMBOL(vmalloc_32_user); 420 421 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 422 { 423 BUG(); 424 return NULL; 425 } 426 EXPORT_SYMBOL(vmap); 427 428 void vunmap(const void *addr) 429 { 430 BUG(); 431 } 432 EXPORT_SYMBOL(vunmap); 433 434 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) 435 { 436 BUG(); 437 return NULL; 438 } 439 EXPORT_SYMBOL(vm_map_ram); 440 441 void vm_unmap_ram(const void *mem, unsigned int count) 442 { 443 BUG(); 444 } 445 EXPORT_SYMBOL(vm_unmap_ram); 446 447 void vm_unmap_aliases(void) 448 { 449 } 450 EXPORT_SYMBOL_GPL(vm_unmap_aliases); 451 452 /* 453 * Implement a stub for vmalloc_sync_all() if the architecture chose not to 454 * have one. 455 */ 456 void __attribute__((weak)) vmalloc_sync_all(void) 457 { 458 } 459 460 /** 461 * alloc_vm_area - allocate a range of kernel address space 462 * @size: size of the area 463 * 464 * Returns: NULL on failure, vm_struct on success 465 * 466 * This function reserves a range of kernel address space, and 467 * allocates pagetables to map that range. No actual mappings 468 * are created. If the kernel address space is not shared 469 * between processes, it syncs the pagetable across all 470 * processes. 471 */ 472 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes) 473 { 474 BUG(); 475 return NULL; 476 } 477 EXPORT_SYMBOL_GPL(alloc_vm_area); 478 479 void free_vm_area(struct vm_struct *area) 480 { 481 BUG(); 482 } 483 EXPORT_SYMBOL_GPL(free_vm_area); 484 485 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 486 struct page *page) 487 { 488 return -EINVAL; 489 } 490 EXPORT_SYMBOL(vm_insert_page); 491 492 /* 493 * sys_brk() for the most part doesn't need the global kernel 494 * lock, except when an application is doing something nasty 495 * like trying to un-brk an area that has already been mapped 496 * to a regular file. in this case, the unmapping will need 497 * to invoke file system routines that need the global lock. 498 */ 499 SYSCALL_DEFINE1(brk, unsigned long, brk) 500 { 501 struct mm_struct *mm = current->mm; 502 503 if (brk < mm->start_brk || brk > mm->context.end_brk) 504 return mm->brk; 505 506 if (mm->brk == brk) 507 return mm->brk; 508 509 /* 510 * Always allow shrinking brk 511 */ 512 if (brk <= mm->brk) { 513 mm->brk = brk; 514 return brk; 515 } 516 517 /* 518 * Ok, looks good - let it rip. 519 */ 520 flush_icache_range(mm->brk, brk); 521 return mm->brk = brk; 522 } 523 524 /* 525 * initialise the VMA and region record slabs 526 */ 527 void __init mmap_init(void) 528 { 529 int ret; 530 531 ret = percpu_counter_init(&vm_committed_as, 0); 532 VM_BUG_ON(ret); 533 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC); 534 } 535 536 /* 537 * validate the region tree 538 * - the caller must hold the region lock 539 */ 540 #ifdef CONFIG_DEBUG_NOMMU_REGIONS 541 static noinline void validate_nommu_regions(void) 542 { 543 struct vm_region *region, *last; 544 struct rb_node *p, *lastp; 545 546 lastp = rb_first(&nommu_region_tree); 547 if (!lastp) 548 return; 549 550 last = rb_entry(lastp, struct vm_region, vm_rb); 551 BUG_ON(unlikely(last->vm_end <= last->vm_start)); 552 BUG_ON(unlikely(last->vm_top < last->vm_end)); 553 554 while ((p = rb_next(lastp))) { 555 region = rb_entry(p, struct vm_region, vm_rb); 556 last = rb_entry(lastp, struct vm_region, vm_rb); 557 558 BUG_ON(unlikely(region->vm_end <= region->vm_start)); 559 BUG_ON(unlikely(region->vm_top < region->vm_end)); 560 BUG_ON(unlikely(region->vm_start < last->vm_top)); 561 562 lastp = p; 563 } 564 } 565 #else 566 static void validate_nommu_regions(void) 567 { 568 } 569 #endif 570 571 /* 572 * add a region into the global tree 573 */ 574 static void add_nommu_region(struct vm_region *region) 575 { 576 struct vm_region *pregion; 577 struct rb_node **p, *parent; 578 579 validate_nommu_regions(); 580 581 parent = NULL; 582 p = &nommu_region_tree.rb_node; 583 while (*p) { 584 parent = *p; 585 pregion = rb_entry(parent, struct vm_region, vm_rb); 586 if (region->vm_start < pregion->vm_start) 587 p = &(*p)->rb_left; 588 else if (region->vm_start > pregion->vm_start) 589 p = &(*p)->rb_right; 590 else if (pregion == region) 591 return; 592 else 593 BUG(); 594 } 595 596 rb_link_node(®ion->vm_rb, parent, p); 597 rb_insert_color(®ion->vm_rb, &nommu_region_tree); 598 599 validate_nommu_regions(); 600 } 601 602 /* 603 * delete a region from the global tree 604 */ 605 static void delete_nommu_region(struct vm_region *region) 606 { 607 BUG_ON(!nommu_region_tree.rb_node); 608 609 validate_nommu_regions(); 610 rb_erase(®ion->vm_rb, &nommu_region_tree); 611 validate_nommu_regions(); 612 } 613 614 /* 615 * free a contiguous series of pages 616 */ 617 static void free_page_series(unsigned long from, unsigned long to) 618 { 619 for (; from < to; from += PAGE_SIZE) { 620 struct page *page = virt_to_page(from); 621 622 kdebug("- free %lx", from); 623 atomic_long_dec(&mmap_pages_allocated); 624 if (page_count(page) != 1) 625 kdebug("free page %p: refcount not one: %d", 626 page, page_count(page)); 627 put_page(page); 628 } 629 } 630 631 /* 632 * release a reference to a region 633 * - the caller must hold the region semaphore for writing, which this releases 634 * - the region may not have been added to the tree yet, in which case vm_top 635 * will equal vm_start 636 */ 637 static void __put_nommu_region(struct vm_region *region) 638 __releases(nommu_region_sem) 639 { 640 kenter("%p{%d}", region, region->vm_usage); 641 642 BUG_ON(!nommu_region_tree.rb_node); 643 644 if (--region->vm_usage == 0) { 645 if (region->vm_top > region->vm_start) 646 delete_nommu_region(region); 647 up_write(&nommu_region_sem); 648 649 if (region->vm_file) 650 fput(region->vm_file); 651 652 /* IO memory and memory shared directly out of the pagecache 653 * from ramfs/tmpfs mustn't be released here */ 654 if (region->vm_flags & VM_MAPPED_COPY) { 655 kdebug("free series"); 656 free_page_series(region->vm_start, region->vm_top); 657 } 658 kmem_cache_free(vm_region_jar, region); 659 } else { 660 up_write(&nommu_region_sem); 661 } 662 } 663 664 /* 665 * release a reference to a region 666 */ 667 static void put_nommu_region(struct vm_region *region) 668 { 669 down_write(&nommu_region_sem); 670 __put_nommu_region(region); 671 } 672 673 /* 674 * update protection on a vma 675 */ 676 static void protect_vma(struct vm_area_struct *vma, unsigned long flags) 677 { 678 #ifdef CONFIG_MPU 679 struct mm_struct *mm = vma->vm_mm; 680 long start = vma->vm_start & PAGE_MASK; 681 while (start < vma->vm_end) { 682 protect_page(mm, start, flags); 683 start += PAGE_SIZE; 684 } 685 update_protections(mm); 686 #endif 687 } 688 689 /* 690 * add a VMA into a process's mm_struct in the appropriate place in the list 691 * and tree and add to the address space's page tree also if not an anonymous 692 * page 693 * - should be called with mm->mmap_sem held writelocked 694 */ 695 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) 696 { 697 struct vm_area_struct *pvma, *prev; 698 struct address_space *mapping; 699 struct rb_node **p, *parent, *rb_prev; 700 701 kenter(",%p", vma); 702 703 BUG_ON(!vma->vm_region); 704 705 mm->map_count++; 706 vma->vm_mm = mm; 707 708 protect_vma(vma, vma->vm_flags); 709 710 /* add the VMA to the mapping */ 711 if (vma->vm_file) { 712 mapping = vma->vm_file->f_mapping; 713 714 mutex_lock(&mapping->i_mmap_mutex); 715 flush_dcache_mmap_lock(mapping); 716 vma_interval_tree_insert(vma, &mapping->i_mmap); 717 flush_dcache_mmap_unlock(mapping); 718 mutex_unlock(&mapping->i_mmap_mutex); 719 } 720 721 /* add the VMA to the tree */ 722 parent = rb_prev = NULL; 723 p = &mm->mm_rb.rb_node; 724 while (*p) { 725 parent = *p; 726 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 727 728 /* sort by: start addr, end addr, VMA struct addr in that order 729 * (the latter is necessary as we may get identical VMAs) */ 730 if (vma->vm_start < pvma->vm_start) 731 p = &(*p)->rb_left; 732 else if (vma->vm_start > pvma->vm_start) { 733 rb_prev = parent; 734 p = &(*p)->rb_right; 735 } else if (vma->vm_end < pvma->vm_end) 736 p = &(*p)->rb_left; 737 else if (vma->vm_end > pvma->vm_end) { 738 rb_prev = parent; 739 p = &(*p)->rb_right; 740 } else if (vma < pvma) 741 p = &(*p)->rb_left; 742 else if (vma > pvma) { 743 rb_prev = parent; 744 p = &(*p)->rb_right; 745 } else 746 BUG(); 747 } 748 749 rb_link_node(&vma->vm_rb, parent, p); 750 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 751 752 /* add VMA to the VMA list also */ 753 prev = NULL; 754 if (rb_prev) 755 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 756 757 __vma_link_list(mm, vma, prev, parent); 758 } 759 760 /* 761 * delete a VMA from its owning mm_struct and address space 762 */ 763 static void delete_vma_from_mm(struct vm_area_struct *vma) 764 { 765 struct address_space *mapping; 766 struct mm_struct *mm = vma->vm_mm; 767 768 kenter("%p", vma); 769 770 protect_vma(vma, 0); 771 772 mm->map_count--; 773 if (mm->mmap_cache == vma) 774 mm->mmap_cache = NULL; 775 776 /* remove the VMA from the mapping */ 777 if (vma->vm_file) { 778 mapping = vma->vm_file->f_mapping; 779 780 mutex_lock(&mapping->i_mmap_mutex); 781 flush_dcache_mmap_lock(mapping); 782 vma_interval_tree_remove(vma, &mapping->i_mmap); 783 flush_dcache_mmap_unlock(mapping); 784 mutex_unlock(&mapping->i_mmap_mutex); 785 } 786 787 /* remove from the MM's tree and list */ 788 rb_erase(&vma->vm_rb, &mm->mm_rb); 789 790 if (vma->vm_prev) 791 vma->vm_prev->vm_next = vma->vm_next; 792 else 793 mm->mmap = vma->vm_next; 794 795 if (vma->vm_next) 796 vma->vm_next->vm_prev = vma->vm_prev; 797 } 798 799 /* 800 * destroy a VMA record 801 */ 802 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) 803 { 804 kenter("%p", vma); 805 if (vma->vm_ops && vma->vm_ops->close) 806 vma->vm_ops->close(vma); 807 if (vma->vm_file) 808 fput(vma->vm_file); 809 put_nommu_region(vma->vm_region); 810 kmem_cache_free(vm_area_cachep, vma); 811 } 812 813 /* 814 * look up the first VMA in which addr resides, NULL if none 815 * - should be called with mm->mmap_sem at least held readlocked 816 */ 817 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 818 { 819 struct vm_area_struct *vma; 820 821 /* check the cache first */ 822 vma = mm->mmap_cache; 823 if (vma && vma->vm_start <= addr && vma->vm_end > addr) 824 return vma; 825 826 /* trawl the list (there may be multiple mappings in which addr 827 * resides) */ 828 for (vma = mm->mmap; vma; vma = vma->vm_next) { 829 if (vma->vm_start > addr) 830 return NULL; 831 if (vma->vm_end > addr) { 832 mm->mmap_cache = vma; 833 return vma; 834 } 835 } 836 837 return NULL; 838 } 839 EXPORT_SYMBOL(find_vma); 840 841 /* 842 * find a VMA 843 * - we don't extend stack VMAs under NOMMU conditions 844 */ 845 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 846 { 847 return find_vma(mm, addr); 848 } 849 850 /* 851 * expand a stack to a given address 852 * - not supported under NOMMU conditions 853 */ 854 int expand_stack(struct vm_area_struct *vma, unsigned long address) 855 { 856 return -ENOMEM; 857 } 858 859 /* 860 * look up the first VMA exactly that exactly matches addr 861 * - should be called with mm->mmap_sem at least held readlocked 862 */ 863 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 864 unsigned long addr, 865 unsigned long len) 866 { 867 struct vm_area_struct *vma; 868 unsigned long end = addr + len; 869 870 /* check the cache first */ 871 vma = mm->mmap_cache; 872 if (vma && vma->vm_start == addr && vma->vm_end == end) 873 return vma; 874 875 /* trawl the list (there may be multiple mappings in which addr 876 * resides) */ 877 for (vma = mm->mmap; vma; vma = vma->vm_next) { 878 if (vma->vm_start < addr) 879 continue; 880 if (vma->vm_start > addr) 881 return NULL; 882 if (vma->vm_end == end) { 883 mm->mmap_cache = vma; 884 return vma; 885 } 886 } 887 888 return NULL; 889 } 890 891 /* 892 * determine whether a mapping should be permitted and, if so, what sort of 893 * mapping we're capable of supporting 894 */ 895 static int validate_mmap_request(struct file *file, 896 unsigned long addr, 897 unsigned long len, 898 unsigned long prot, 899 unsigned long flags, 900 unsigned long pgoff, 901 unsigned long *_capabilities) 902 { 903 unsigned long capabilities, rlen; 904 int ret; 905 906 /* do the simple checks first */ 907 if (flags & MAP_FIXED) { 908 printk(KERN_DEBUG 909 "%d: Can't do fixed-address/overlay mmap of RAM\n", 910 current->pid); 911 return -EINVAL; 912 } 913 914 if ((flags & MAP_TYPE) != MAP_PRIVATE && 915 (flags & MAP_TYPE) != MAP_SHARED) 916 return -EINVAL; 917 918 if (!len) 919 return -EINVAL; 920 921 /* Careful about overflows.. */ 922 rlen = PAGE_ALIGN(len); 923 if (!rlen || rlen > TASK_SIZE) 924 return -ENOMEM; 925 926 /* offset overflow? */ 927 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) 928 return -EOVERFLOW; 929 930 if (file) { 931 /* validate file mapping requests */ 932 struct address_space *mapping; 933 934 /* files must support mmap */ 935 if (!file->f_op || !file->f_op->mmap) 936 return -ENODEV; 937 938 /* work out if what we've got could possibly be shared 939 * - we support chardevs that provide their own "memory" 940 * - we support files/blockdevs that are memory backed 941 */ 942 mapping = file->f_mapping; 943 if (!mapping) 944 mapping = file->f_path.dentry->d_inode->i_mapping; 945 946 capabilities = 0; 947 if (mapping && mapping->backing_dev_info) 948 capabilities = mapping->backing_dev_info->capabilities; 949 950 if (!capabilities) { 951 /* no explicit capabilities set, so assume some 952 * defaults */ 953 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) { 954 case S_IFREG: 955 case S_IFBLK: 956 capabilities = BDI_CAP_MAP_COPY; 957 break; 958 959 case S_IFCHR: 960 capabilities = 961 BDI_CAP_MAP_DIRECT | 962 BDI_CAP_READ_MAP | 963 BDI_CAP_WRITE_MAP; 964 break; 965 966 default: 967 return -EINVAL; 968 } 969 } 970 971 /* eliminate any capabilities that we can't support on this 972 * device */ 973 if (!file->f_op->get_unmapped_area) 974 capabilities &= ~BDI_CAP_MAP_DIRECT; 975 if (!file->f_op->read) 976 capabilities &= ~BDI_CAP_MAP_COPY; 977 978 /* The file shall have been opened with read permission. */ 979 if (!(file->f_mode & FMODE_READ)) 980 return -EACCES; 981 982 if (flags & MAP_SHARED) { 983 /* do checks for writing, appending and locking */ 984 if ((prot & PROT_WRITE) && 985 !(file->f_mode & FMODE_WRITE)) 986 return -EACCES; 987 988 if (IS_APPEND(file->f_path.dentry->d_inode) && 989 (file->f_mode & FMODE_WRITE)) 990 return -EACCES; 991 992 if (locks_verify_locked(file->f_path.dentry->d_inode)) 993 return -EAGAIN; 994 995 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 996 return -ENODEV; 997 998 /* we mustn't privatise shared mappings */ 999 capabilities &= ~BDI_CAP_MAP_COPY; 1000 } 1001 else { 1002 /* we're going to read the file into private memory we 1003 * allocate */ 1004 if (!(capabilities & BDI_CAP_MAP_COPY)) 1005 return -ENODEV; 1006 1007 /* we don't permit a private writable mapping to be 1008 * shared with the backing device */ 1009 if (prot & PROT_WRITE) 1010 capabilities &= ~BDI_CAP_MAP_DIRECT; 1011 } 1012 1013 if (capabilities & BDI_CAP_MAP_DIRECT) { 1014 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 1015 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 1016 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 1017 ) { 1018 capabilities &= ~BDI_CAP_MAP_DIRECT; 1019 if (flags & MAP_SHARED) { 1020 printk(KERN_WARNING 1021 "MAP_SHARED not completely supported on !MMU\n"); 1022 return -EINVAL; 1023 } 1024 } 1025 } 1026 1027 /* handle executable mappings and implied executable 1028 * mappings */ 1029 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1030 if (prot & PROT_EXEC) 1031 return -EPERM; 1032 } 1033 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 1034 /* handle implication of PROT_EXEC by PROT_READ */ 1035 if (current->personality & READ_IMPLIES_EXEC) { 1036 if (capabilities & BDI_CAP_EXEC_MAP) 1037 prot |= PROT_EXEC; 1038 } 1039 } 1040 else if ((prot & PROT_READ) && 1041 (prot & PROT_EXEC) && 1042 !(capabilities & BDI_CAP_EXEC_MAP) 1043 ) { 1044 /* backing file is not executable, try to copy */ 1045 capabilities &= ~BDI_CAP_MAP_DIRECT; 1046 } 1047 } 1048 else { 1049 /* anonymous mappings are always memory backed and can be 1050 * privately mapped 1051 */ 1052 capabilities = BDI_CAP_MAP_COPY; 1053 1054 /* handle PROT_EXEC implication by PROT_READ */ 1055 if ((prot & PROT_READ) && 1056 (current->personality & READ_IMPLIES_EXEC)) 1057 prot |= PROT_EXEC; 1058 } 1059 1060 /* allow the security API to have its say */ 1061 ret = security_mmap_addr(addr); 1062 if (ret < 0) 1063 return ret; 1064 1065 /* looks okay */ 1066 *_capabilities = capabilities; 1067 return 0; 1068 } 1069 1070 /* 1071 * we've determined that we can make the mapping, now translate what we 1072 * now know into VMA flags 1073 */ 1074 static unsigned long determine_vm_flags(struct file *file, 1075 unsigned long prot, 1076 unsigned long flags, 1077 unsigned long capabilities) 1078 { 1079 unsigned long vm_flags; 1080 1081 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 1082 /* vm_flags |= mm->def_flags; */ 1083 1084 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 1085 /* attempt to share read-only copies of mapped file chunks */ 1086 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1087 if (file && !(prot & PROT_WRITE)) 1088 vm_flags |= VM_MAYSHARE; 1089 } else { 1090 /* overlay a shareable mapping on the backing device or inode 1091 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 1092 * romfs/cramfs */ 1093 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS); 1094 if (flags & MAP_SHARED) 1095 vm_flags |= VM_SHARED; 1096 } 1097 1098 /* refuse to let anyone share private mappings with this process if 1099 * it's being traced - otherwise breakpoints set in it may interfere 1100 * with another untraced process 1101 */ 1102 if ((flags & MAP_PRIVATE) && current->ptrace) 1103 vm_flags &= ~VM_MAYSHARE; 1104 1105 return vm_flags; 1106 } 1107 1108 /* 1109 * set up a shared mapping on a file (the driver or filesystem provides and 1110 * pins the storage) 1111 */ 1112 static int do_mmap_shared_file(struct vm_area_struct *vma) 1113 { 1114 int ret; 1115 1116 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1117 if (ret == 0) { 1118 vma->vm_region->vm_top = vma->vm_region->vm_end; 1119 return 0; 1120 } 1121 if (ret != -ENOSYS) 1122 return ret; 1123 1124 /* getting -ENOSYS indicates that direct mmap isn't possible (as 1125 * opposed to tried but failed) so we can only give a suitable error as 1126 * it's not possible to make a private copy if MAP_SHARED was given */ 1127 return -ENODEV; 1128 } 1129 1130 /* 1131 * set up a private mapping or an anonymous shared mapping 1132 */ 1133 static int do_mmap_private(struct vm_area_struct *vma, 1134 struct vm_region *region, 1135 unsigned long len, 1136 unsigned long capabilities) 1137 { 1138 struct page *pages; 1139 unsigned long total, point, n; 1140 void *base; 1141 int ret, order; 1142 1143 /* invoke the file's mapping function so that it can keep track of 1144 * shared mappings on devices or memory 1145 * - VM_MAYSHARE will be set if it may attempt to share 1146 */ 1147 if (capabilities & BDI_CAP_MAP_DIRECT) { 1148 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1149 if (ret == 0) { 1150 /* shouldn't return success if we're not sharing */ 1151 BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); 1152 vma->vm_region->vm_top = vma->vm_region->vm_end; 1153 return 0; 1154 } 1155 if (ret != -ENOSYS) 1156 return ret; 1157 1158 /* getting an ENOSYS error indicates that direct mmap isn't 1159 * possible (as opposed to tried but failed) so we'll try to 1160 * make a private copy of the data and map that instead */ 1161 } 1162 1163 1164 /* allocate some memory to hold the mapping 1165 * - note that this may not return a page-aligned address if the object 1166 * we're allocating is smaller than a page 1167 */ 1168 order = get_order(len); 1169 kdebug("alloc order %d for %lx", order, len); 1170 1171 pages = alloc_pages(GFP_KERNEL, order); 1172 if (!pages) 1173 goto enomem; 1174 1175 total = 1 << order; 1176 atomic_long_add(total, &mmap_pages_allocated); 1177 1178 point = len >> PAGE_SHIFT; 1179 1180 /* we allocated a power-of-2 sized page set, so we may want to trim off 1181 * the excess */ 1182 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) { 1183 while (total > point) { 1184 order = ilog2(total - point); 1185 n = 1 << order; 1186 kdebug("shave %lu/%lu @%lu", n, total - point, total); 1187 atomic_long_sub(n, &mmap_pages_allocated); 1188 total -= n; 1189 set_page_refcounted(pages + total); 1190 __free_pages(pages + total, order); 1191 } 1192 } 1193 1194 for (point = 1; point < total; point++) 1195 set_page_refcounted(&pages[point]); 1196 1197 base = page_address(pages); 1198 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; 1199 region->vm_start = (unsigned long) base; 1200 region->vm_end = region->vm_start + len; 1201 region->vm_top = region->vm_start + (total << PAGE_SHIFT); 1202 1203 vma->vm_start = region->vm_start; 1204 vma->vm_end = region->vm_start + len; 1205 1206 if (vma->vm_file) { 1207 /* read the contents of a file into the copy */ 1208 mm_segment_t old_fs; 1209 loff_t fpos; 1210 1211 fpos = vma->vm_pgoff; 1212 fpos <<= PAGE_SHIFT; 1213 1214 old_fs = get_fs(); 1215 set_fs(KERNEL_DS); 1216 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos); 1217 set_fs(old_fs); 1218 1219 if (ret < 0) 1220 goto error_free; 1221 1222 /* clear the last little bit */ 1223 if (ret < len) 1224 memset(base + ret, 0, len - ret); 1225 1226 } 1227 1228 return 0; 1229 1230 error_free: 1231 free_page_series(region->vm_start, region->vm_top); 1232 region->vm_start = vma->vm_start = 0; 1233 region->vm_end = vma->vm_end = 0; 1234 region->vm_top = 0; 1235 return ret; 1236 1237 enomem: 1238 printk("Allocation of length %lu from process %d (%s) failed\n", 1239 len, current->pid, current->comm); 1240 show_free_areas(0); 1241 return -ENOMEM; 1242 } 1243 1244 /* 1245 * handle mapping creation for uClinux 1246 */ 1247 unsigned long do_mmap_pgoff(struct file *file, 1248 unsigned long addr, 1249 unsigned long len, 1250 unsigned long prot, 1251 unsigned long flags, 1252 unsigned long pgoff) 1253 { 1254 struct vm_area_struct *vma; 1255 struct vm_region *region; 1256 struct rb_node *rb; 1257 unsigned long capabilities, vm_flags, result; 1258 int ret; 1259 1260 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff); 1261 1262 /* decide whether we should attempt the mapping, and if so what sort of 1263 * mapping */ 1264 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 1265 &capabilities); 1266 if (ret < 0) { 1267 kleave(" = %d [val]", ret); 1268 return ret; 1269 } 1270 1271 /* we ignore the address hint */ 1272 addr = 0; 1273 len = PAGE_ALIGN(len); 1274 1275 /* we've determined that we can make the mapping, now translate what we 1276 * now know into VMA flags */ 1277 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 1278 1279 /* we're going to need to record the mapping */ 1280 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); 1281 if (!region) 1282 goto error_getting_region; 1283 1284 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1285 if (!vma) 1286 goto error_getting_vma; 1287 1288 region->vm_usage = 1; 1289 region->vm_flags = vm_flags; 1290 region->vm_pgoff = pgoff; 1291 1292 INIT_LIST_HEAD(&vma->anon_vma_chain); 1293 vma->vm_flags = vm_flags; 1294 vma->vm_pgoff = pgoff; 1295 1296 if (file) { 1297 region->vm_file = get_file(file); 1298 vma->vm_file = get_file(file); 1299 } 1300 1301 down_write(&nommu_region_sem); 1302 1303 /* if we want to share, we need to check for regions created by other 1304 * mmap() calls that overlap with our proposed mapping 1305 * - we can only share with a superset match on most regular files 1306 * - shared mappings on character devices and memory backed files are 1307 * permitted to overlap inexactly as far as we are concerned for in 1308 * these cases, sharing is handled in the driver or filesystem rather 1309 * than here 1310 */ 1311 if (vm_flags & VM_MAYSHARE) { 1312 struct vm_region *pregion; 1313 unsigned long pglen, rpglen, pgend, rpgend, start; 1314 1315 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1316 pgend = pgoff + pglen; 1317 1318 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { 1319 pregion = rb_entry(rb, struct vm_region, vm_rb); 1320 1321 if (!(pregion->vm_flags & VM_MAYSHARE)) 1322 continue; 1323 1324 /* search for overlapping mappings on the same file */ 1325 if (pregion->vm_file->f_path.dentry->d_inode != 1326 file->f_path.dentry->d_inode) 1327 continue; 1328 1329 if (pregion->vm_pgoff >= pgend) 1330 continue; 1331 1332 rpglen = pregion->vm_end - pregion->vm_start; 1333 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1334 rpgend = pregion->vm_pgoff + rpglen; 1335 if (pgoff >= rpgend) 1336 continue; 1337 1338 /* handle inexactly overlapping matches between 1339 * mappings */ 1340 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && 1341 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { 1342 /* new mapping is not a subset of the region */ 1343 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 1344 goto sharing_violation; 1345 continue; 1346 } 1347 1348 /* we've found a region we can share */ 1349 pregion->vm_usage++; 1350 vma->vm_region = pregion; 1351 start = pregion->vm_start; 1352 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; 1353 vma->vm_start = start; 1354 vma->vm_end = start + len; 1355 1356 if (pregion->vm_flags & VM_MAPPED_COPY) { 1357 kdebug("share copy"); 1358 vma->vm_flags |= VM_MAPPED_COPY; 1359 } else { 1360 kdebug("share mmap"); 1361 ret = do_mmap_shared_file(vma); 1362 if (ret < 0) { 1363 vma->vm_region = NULL; 1364 vma->vm_start = 0; 1365 vma->vm_end = 0; 1366 pregion->vm_usage--; 1367 pregion = NULL; 1368 goto error_just_free; 1369 } 1370 } 1371 fput(region->vm_file); 1372 kmem_cache_free(vm_region_jar, region); 1373 region = pregion; 1374 result = start; 1375 goto share; 1376 } 1377 1378 /* obtain the address at which to make a shared mapping 1379 * - this is the hook for quasi-memory character devices to 1380 * tell us the location of a shared mapping 1381 */ 1382 if (capabilities & BDI_CAP_MAP_DIRECT) { 1383 addr = file->f_op->get_unmapped_area(file, addr, len, 1384 pgoff, flags); 1385 if (IS_ERR_VALUE(addr)) { 1386 ret = addr; 1387 if (ret != -ENOSYS) 1388 goto error_just_free; 1389 1390 /* the driver refused to tell us where to site 1391 * the mapping so we'll have to attempt to copy 1392 * it */ 1393 ret = -ENODEV; 1394 if (!(capabilities & BDI_CAP_MAP_COPY)) 1395 goto error_just_free; 1396 1397 capabilities &= ~BDI_CAP_MAP_DIRECT; 1398 } else { 1399 vma->vm_start = region->vm_start = addr; 1400 vma->vm_end = region->vm_end = addr + len; 1401 } 1402 } 1403 } 1404 1405 vma->vm_region = region; 1406 1407 /* set up the mapping 1408 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set 1409 */ 1410 if (file && vma->vm_flags & VM_SHARED) 1411 ret = do_mmap_shared_file(vma); 1412 else 1413 ret = do_mmap_private(vma, region, len, capabilities); 1414 if (ret < 0) 1415 goto error_just_free; 1416 add_nommu_region(region); 1417 1418 /* clear anonymous mappings that don't ask for uninitialized data */ 1419 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) 1420 memset((void *)region->vm_start, 0, 1421 region->vm_end - region->vm_start); 1422 1423 /* okay... we have a mapping; now we have to register it */ 1424 result = vma->vm_start; 1425 1426 current->mm->total_vm += len >> PAGE_SHIFT; 1427 1428 share: 1429 add_vma_to_mm(current->mm, vma); 1430 1431 /* we flush the region from the icache only when the first executable 1432 * mapping of it is made */ 1433 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { 1434 flush_icache_range(region->vm_start, region->vm_end); 1435 region->vm_icache_flushed = true; 1436 } 1437 1438 up_write(&nommu_region_sem); 1439 1440 kleave(" = %lx", result); 1441 return result; 1442 1443 error_just_free: 1444 up_write(&nommu_region_sem); 1445 error: 1446 if (region->vm_file) 1447 fput(region->vm_file); 1448 kmem_cache_free(vm_region_jar, region); 1449 if (vma->vm_file) 1450 fput(vma->vm_file); 1451 kmem_cache_free(vm_area_cachep, vma); 1452 kleave(" = %d", ret); 1453 return ret; 1454 1455 sharing_violation: 1456 up_write(&nommu_region_sem); 1457 printk(KERN_WARNING "Attempt to share mismatched mappings\n"); 1458 ret = -EINVAL; 1459 goto error; 1460 1461 error_getting_vma: 1462 kmem_cache_free(vm_region_jar, region); 1463 printk(KERN_WARNING "Allocation of vma for %lu byte allocation" 1464 " from process %d failed\n", 1465 len, current->pid); 1466 show_free_areas(0); 1467 return -ENOMEM; 1468 1469 error_getting_region: 1470 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation" 1471 " from process %d failed\n", 1472 len, current->pid); 1473 show_free_areas(0); 1474 return -ENOMEM; 1475 } 1476 1477 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1478 unsigned long, prot, unsigned long, flags, 1479 unsigned long, fd, unsigned long, pgoff) 1480 { 1481 struct file *file = NULL; 1482 unsigned long retval = -EBADF; 1483 1484 audit_mmap_fd(fd, flags); 1485 if (!(flags & MAP_ANONYMOUS)) { 1486 file = fget(fd); 1487 if (!file) 1488 goto out; 1489 } 1490 1491 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1492 1493 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1494 1495 if (file) 1496 fput(file); 1497 out: 1498 return retval; 1499 } 1500 1501 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1502 struct mmap_arg_struct { 1503 unsigned long addr; 1504 unsigned long len; 1505 unsigned long prot; 1506 unsigned long flags; 1507 unsigned long fd; 1508 unsigned long offset; 1509 }; 1510 1511 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1512 { 1513 struct mmap_arg_struct a; 1514 1515 if (copy_from_user(&a, arg, sizeof(a))) 1516 return -EFAULT; 1517 if (a.offset & ~PAGE_MASK) 1518 return -EINVAL; 1519 1520 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1521 a.offset >> PAGE_SHIFT); 1522 } 1523 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1524 1525 /* 1526 * split a vma into two pieces at address 'addr', a new vma is allocated either 1527 * for the first part or the tail. 1528 */ 1529 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 1530 unsigned long addr, int new_below) 1531 { 1532 struct vm_area_struct *new; 1533 struct vm_region *region; 1534 unsigned long npages; 1535 1536 kenter(""); 1537 1538 /* we're only permitted to split anonymous regions (these should have 1539 * only a single usage on the region) */ 1540 if (vma->vm_file) 1541 return -ENOMEM; 1542 1543 if (mm->map_count >= sysctl_max_map_count) 1544 return -ENOMEM; 1545 1546 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); 1547 if (!region) 1548 return -ENOMEM; 1549 1550 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1551 if (!new) { 1552 kmem_cache_free(vm_region_jar, region); 1553 return -ENOMEM; 1554 } 1555 1556 /* most fields are the same, copy all, and then fixup */ 1557 *new = *vma; 1558 *region = *vma->vm_region; 1559 new->vm_region = region; 1560 1561 npages = (addr - vma->vm_start) >> PAGE_SHIFT; 1562 1563 if (new_below) { 1564 region->vm_top = region->vm_end = new->vm_end = addr; 1565 } else { 1566 region->vm_start = new->vm_start = addr; 1567 region->vm_pgoff = new->vm_pgoff += npages; 1568 } 1569 1570 if (new->vm_ops && new->vm_ops->open) 1571 new->vm_ops->open(new); 1572 1573 delete_vma_from_mm(vma); 1574 down_write(&nommu_region_sem); 1575 delete_nommu_region(vma->vm_region); 1576 if (new_below) { 1577 vma->vm_region->vm_start = vma->vm_start = addr; 1578 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; 1579 } else { 1580 vma->vm_region->vm_end = vma->vm_end = addr; 1581 vma->vm_region->vm_top = addr; 1582 } 1583 add_nommu_region(vma->vm_region); 1584 add_nommu_region(new->vm_region); 1585 up_write(&nommu_region_sem); 1586 add_vma_to_mm(mm, vma); 1587 add_vma_to_mm(mm, new); 1588 return 0; 1589 } 1590 1591 /* 1592 * shrink a VMA by removing the specified chunk from either the beginning or 1593 * the end 1594 */ 1595 static int shrink_vma(struct mm_struct *mm, 1596 struct vm_area_struct *vma, 1597 unsigned long from, unsigned long to) 1598 { 1599 struct vm_region *region; 1600 1601 kenter(""); 1602 1603 /* adjust the VMA's pointers, which may reposition it in the MM's tree 1604 * and list */ 1605 delete_vma_from_mm(vma); 1606 if (from > vma->vm_start) 1607 vma->vm_end = from; 1608 else 1609 vma->vm_start = to; 1610 add_vma_to_mm(mm, vma); 1611 1612 /* cut the backing region down to size */ 1613 region = vma->vm_region; 1614 BUG_ON(region->vm_usage != 1); 1615 1616 down_write(&nommu_region_sem); 1617 delete_nommu_region(region); 1618 if (from > region->vm_start) { 1619 to = region->vm_top; 1620 region->vm_top = region->vm_end = from; 1621 } else { 1622 region->vm_start = to; 1623 } 1624 add_nommu_region(region); 1625 up_write(&nommu_region_sem); 1626 1627 free_page_series(from, to); 1628 return 0; 1629 } 1630 1631 /* 1632 * release a mapping 1633 * - under NOMMU conditions the chunk to be unmapped must be backed by a single 1634 * VMA, though it need not cover the whole VMA 1635 */ 1636 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1637 { 1638 struct vm_area_struct *vma; 1639 unsigned long end; 1640 int ret; 1641 1642 kenter(",%lx,%zx", start, len); 1643 1644 len = PAGE_ALIGN(len); 1645 if (len == 0) 1646 return -EINVAL; 1647 1648 end = start + len; 1649 1650 /* find the first potentially overlapping VMA */ 1651 vma = find_vma(mm, start); 1652 if (!vma) { 1653 static int limit = 0; 1654 if (limit < 5) { 1655 printk(KERN_WARNING 1656 "munmap of memory not mmapped by process %d" 1657 " (%s): 0x%lx-0x%lx\n", 1658 current->pid, current->comm, 1659 start, start + len - 1); 1660 limit++; 1661 } 1662 return -EINVAL; 1663 } 1664 1665 /* we're allowed to split an anonymous VMA but not a file-backed one */ 1666 if (vma->vm_file) { 1667 do { 1668 if (start > vma->vm_start) { 1669 kleave(" = -EINVAL [miss]"); 1670 return -EINVAL; 1671 } 1672 if (end == vma->vm_end) 1673 goto erase_whole_vma; 1674 vma = vma->vm_next; 1675 } while (vma); 1676 kleave(" = -EINVAL [split file]"); 1677 return -EINVAL; 1678 } else { 1679 /* the chunk must be a subset of the VMA found */ 1680 if (start == vma->vm_start && end == vma->vm_end) 1681 goto erase_whole_vma; 1682 if (start < vma->vm_start || end > vma->vm_end) { 1683 kleave(" = -EINVAL [superset]"); 1684 return -EINVAL; 1685 } 1686 if (start & ~PAGE_MASK) { 1687 kleave(" = -EINVAL [unaligned start]"); 1688 return -EINVAL; 1689 } 1690 if (end != vma->vm_end && end & ~PAGE_MASK) { 1691 kleave(" = -EINVAL [unaligned split]"); 1692 return -EINVAL; 1693 } 1694 if (start != vma->vm_start && end != vma->vm_end) { 1695 ret = split_vma(mm, vma, start, 1); 1696 if (ret < 0) { 1697 kleave(" = %d [split]", ret); 1698 return ret; 1699 } 1700 } 1701 return shrink_vma(mm, vma, start, end); 1702 } 1703 1704 erase_whole_vma: 1705 delete_vma_from_mm(vma); 1706 delete_vma(mm, vma); 1707 kleave(" = 0"); 1708 return 0; 1709 } 1710 EXPORT_SYMBOL(do_munmap); 1711 1712 int vm_munmap(unsigned long addr, size_t len) 1713 { 1714 struct mm_struct *mm = current->mm; 1715 int ret; 1716 1717 down_write(&mm->mmap_sem); 1718 ret = do_munmap(mm, addr, len); 1719 up_write(&mm->mmap_sem); 1720 return ret; 1721 } 1722 EXPORT_SYMBOL(vm_munmap); 1723 1724 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1725 { 1726 return vm_munmap(addr, len); 1727 } 1728 1729 /* 1730 * release all the mappings made in a process's VM space 1731 */ 1732 void exit_mmap(struct mm_struct *mm) 1733 { 1734 struct vm_area_struct *vma; 1735 1736 if (!mm) 1737 return; 1738 1739 kenter(""); 1740 1741 mm->total_vm = 0; 1742 1743 while ((vma = mm->mmap)) { 1744 mm->mmap = vma->vm_next; 1745 delete_vma_from_mm(vma); 1746 delete_vma(mm, vma); 1747 cond_resched(); 1748 } 1749 1750 kleave(""); 1751 } 1752 1753 unsigned long vm_brk(unsigned long addr, unsigned long len) 1754 { 1755 return -ENOMEM; 1756 } 1757 1758 /* 1759 * expand (or shrink) an existing mapping, potentially moving it at the same 1760 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1761 * 1762 * under NOMMU conditions, we only permit changing a mapping's size, and only 1763 * as long as it stays within the region allocated by do_mmap_private() and the 1764 * block is not shareable 1765 * 1766 * MREMAP_FIXED is not supported under NOMMU conditions 1767 */ 1768 unsigned long do_mremap(unsigned long addr, 1769 unsigned long old_len, unsigned long new_len, 1770 unsigned long flags, unsigned long new_addr) 1771 { 1772 struct vm_area_struct *vma; 1773 1774 /* insanity checks first */ 1775 old_len = PAGE_ALIGN(old_len); 1776 new_len = PAGE_ALIGN(new_len); 1777 if (old_len == 0 || new_len == 0) 1778 return (unsigned long) -EINVAL; 1779 1780 if (addr & ~PAGE_MASK) 1781 return -EINVAL; 1782 1783 if (flags & MREMAP_FIXED && new_addr != addr) 1784 return (unsigned long) -EINVAL; 1785 1786 vma = find_vma_exact(current->mm, addr, old_len); 1787 if (!vma) 1788 return (unsigned long) -EINVAL; 1789 1790 if (vma->vm_end != vma->vm_start + old_len) 1791 return (unsigned long) -EFAULT; 1792 1793 if (vma->vm_flags & VM_MAYSHARE) 1794 return (unsigned long) -EPERM; 1795 1796 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) 1797 return (unsigned long) -ENOMEM; 1798 1799 /* all checks complete - do it */ 1800 vma->vm_end = vma->vm_start + new_len; 1801 return vma->vm_start; 1802 } 1803 EXPORT_SYMBOL(do_mremap); 1804 1805 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, 1806 unsigned long, new_len, unsigned long, flags, 1807 unsigned long, new_addr) 1808 { 1809 unsigned long ret; 1810 1811 down_write(¤t->mm->mmap_sem); 1812 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1813 up_write(¤t->mm->mmap_sem); 1814 return ret; 1815 } 1816 1817 struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1818 unsigned int foll_flags) 1819 { 1820 return NULL; 1821 } 1822 1823 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1824 unsigned long pfn, unsigned long size, pgprot_t prot) 1825 { 1826 if (addr != (pfn << PAGE_SHIFT)) 1827 return -EINVAL; 1828 1829 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 1830 return 0; 1831 } 1832 EXPORT_SYMBOL(remap_pfn_range); 1833 1834 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 1835 unsigned long pgoff) 1836 { 1837 unsigned int size = vma->vm_end - vma->vm_start; 1838 1839 if (!(vma->vm_flags & VM_USERMAP)) 1840 return -EINVAL; 1841 1842 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); 1843 vma->vm_end = vma->vm_start + size; 1844 1845 return 0; 1846 } 1847 EXPORT_SYMBOL(remap_vmalloc_range); 1848 1849 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1850 unsigned long len, unsigned long pgoff, unsigned long flags) 1851 { 1852 return -ENOMEM; 1853 } 1854 1855 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1856 { 1857 } 1858 1859 void unmap_mapping_range(struct address_space *mapping, 1860 loff_t const holebegin, loff_t const holelen, 1861 int even_cows) 1862 { 1863 } 1864 EXPORT_SYMBOL(unmap_mapping_range); 1865 1866 /* 1867 * Check that a process has enough memory to allocate a new virtual 1868 * mapping. 0 means there is enough memory for the allocation to 1869 * succeed and -ENOMEM implies there is not. 1870 * 1871 * We currently support three overcommit policies, which are set via the 1872 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1873 * 1874 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1875 * Additional code 2002 Jul 20 by Robert Love. 1876 * 1877 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1878 * 1879 * Note this is a helper function intended to be used by LSMs which 1880 * wish to use this logic. 1881 */ 1882 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 1883 { 1884 unsigned long free, allowed; 1885 1886 vm_acct_memory(pages); 1887 1888 /* 1889 * Sometimes we want to use more memory than we have 1890 */ 1891 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1892 return 0; 1893 1894 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1895 free = global_page_state(NR_FREE_PAGES); 1896 free += global_page_state(NR_FILE_PAGES); 1897 1898 /* 1899 * shmem pages shouldn't be counted as free in this 1900 * case, they can't be purged, only swapped out, and 1901 * that won't affect the overall amount of available 1902 * memory in the system. 1903 */ 1904 free -= global_page_state(NR_SHMEM); 1905 1906 free += nr_swap_pages; 1907 1908 /* 1909 * Any slabs which are created with the 1910 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1911 * which are reclaimable, under pressure. The dentry 1912 * cache and most inode caches should fall into this 1913 */ 1914 free += global_page_state(NR_SLAB_RECLAIMABLE); 1915 1916 /* 1917 * Leave reserved pages. The pages are not for anonymous pages. 1918 */ 1919 if (free <= totalreserve_pages) 1920 goto error; 1921 else 1922 free -= totalreserve_pages; 1923 1924 /* 1925 * Leave the last 3% for root 1926 */ 1927 if (!cap_sys_admin) 1928 free -= free / 32; 1929 1930 if (free > pages) 1931 return 0; 1932 1933 goto error; 1934 } 1935 1936 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1937 /* 1938 * Leave the last 3% for root 1939 */ 1940 if (!cap_sys_admin) 1941 allowed -= allowed / 32; 1942 allowed += total_swap_pages; 1943 1944 /* Don't let a single process grow too big: 1945 leave 3% of the size of this process for other processes */ 1946 if (mm) 1947 allowed -= mm->total_vm / 32; 1948 1949 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 1950 return 0; 1951 1952 error: 1953 vm_unacct_memory(pages); 1954 1955 return -ENOMEM; 1956 } 1957 1958 int in_gate_area_no_mm(unsigned long addr) 1959 { 1960 return 0; 1961 } 1962 1963 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1964 { 1965 BUG(); 1966 return 0; 1967 } 1968 EXPORT_SYMBOL(filemap_fault); 1969 1970 int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr, 1971 unsigned long size, pgoff_t pgoff) 1972 { 1973 BUG(); 1974 return 0; 1975 } 1976 EXPORT_SYMBOL(generic_file_remap_pages); 1977 1978 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 1979 unsigned long addr, void *buf, int len, int write) 1980 { 1981 struct vm_area_struct *vma; 1982 1983 down_read(&mm->mmap_sem); 1984 1985 /* the access must start within one of the target process's mappings */ 1986 vma = find_vma(mm, addr); 1987 if (vma) { 1988 /* don't overrun this mapping */ 1989 if (addr + len >= vma->vm_end) 1990 len = vma->vm_end - addr; 1991 1992 /* only read or write mappings where it is permitted */ 1993 if (write && vma->vm_flags & VM_MAYWRITE) 1994 copy_to_user_page(vma, NULL, addr, 1995 (void *) addr, buf, len); 1996 else if (!write && vma->vm_flags & VM_MAYREAD) 1997 copy_from_user_page(vma, NULL, addr, 1998 buf, (void *) addr, len); 1999 else 2000 len = 0; 2001 } else { 2002 len = 0; 2003 } 2004 2005 up_read(&mm->mmap_sem); 2006 2007 return len; 2008 } 2009 2010 /** 2011 * @access_remote_vm - access another process' address space 2012 * @mm: the mm_struct of the target address space 2013 * @addr: start address to access 2014 * @buf: source or destination buffer 2015 * @len: number of bytes to transfer 2016 * @write: whether the access is a write 2017 * 2018 * The caller must hold a reference on @mm. 2019 */ 2020 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 2021 void *buf, int len, int write) 2022 { 2023 return __access_remote_vm(NULL, mm, addr, buf, len, write); 2024 } 2025 2026 /* 2027 * Access another process' address space. 2028 * - source/target buffer must be kernel space 2029 */ 2030 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2031 { 2032 struct mm_struct *mm; 2033 2034 if (addr + len < addr) 2035 return 0; 2036 2037 mm = get_task_mm(tsk); 2038 if (!mm) 2039 return 0; 2040 2041 len = __access_remote_vm(tsk, mm, addr, buf, len, write); 2042 2043 mmput(mm); 2044 return len; 2045 } 2046 2047 /** 2048 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode 2049 * @inode: The inode to check 2050 * @size: The current filesize of the inode 2051 * @newsize: The proposed filesize of the inode 2052 * 2053 * Check the shared mappings on an inode on behalf of a shrinking truncate to 2054 * make sure that that any outstanding VMAs aren't broken and then shrink the 2055 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't 2056 * automatically grant mappings that are too large. 2057 */ 2058 int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 2059 size_t newsize) 2060 { 2061 struct vm_area_struct *vma; 2062 struct vm_region *region; 2063 pgoff_t low, high; 2064 size_t r_size, r_top; 2065 2066 low = newsize >> PAGE_SHIFT; 2067 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 2068 2069 down_write(&nommu_region_sem); 2070 mutex_lock(&inode->i_mapping->i_mmap_mutex); 2071 2072 /* search for VMAs that fall within the dead zone */ 2073 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { 2074 /* found one - only interested if it's shared out of the page 2075 * cache */ 2076 if (vma->vm_flags & VM_SHARED) { 2077 mutex_unlock(&inode->i_mapping->i_mmap_mutex); 2078 up_write(&nommu_region_sem); 2079 return -ETXTBSY; /* not quite true, but near enough */ 2080 } 2081 } 2082 2083 /* reduce any regions that overlap the dead zone - if in existence, 2084 * these will be pointed to by VMAs that don't overlap the dead zone 2085 * 2086 * we don't check for any regions that start beyond the EOF as there 2087 * shouldn't be any 2088 */ 2089 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 2090 0, ULONG_MAX) { 2091 if (!(vma->vm_flags & VM_SHARED)) 2092 continue; 2093 2094 region = vma->vm_region; 2095 r_size = region->vm_top - region->vm_start; 2096 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; 2097 2098 if (r_top > newsize) { 2099 region->vm_top -= r_top - newsize; 2100 if (region->vm_end > region->vm_top) 2101 region->vm_end = region->vm_top; 2102 } 2103 } 2104 2105 mutex_unlock(&inode->i_mapping->i_mmap_mutex); 2106 up_write(&nommu_region_sem); 2107 return 0; 2108 } 2109