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 #include <linux/sched/sysctl.h> 33 34 #include <asm/uaccess.h> 35 #include <asm/tlb.h> 36 #include <asm/tlbflush.h> 37 #include <asm/mmu_context.h> 38 #include "internal.h" 39 40 #if 0 41 #define kenter(FMT, ...) \ 42 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 43 #define kleave(FMT, ...) \ 44 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 45 #define kdebug(FMT, ...) \ 46 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__) 47 #else 48 #define kenter(FMT, ...) \ 49 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 50 #define kleave(FMT, ...) \ 51 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 52 #define kdebug(FMT, ...) \ 53 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__) 54 #endif 55 56 void *high_memory; 57 struct page *mem_map; 58 unsigned long max_mapnr; 59 unsigned long num_physpages; 60 unsigned long highest_memmap_pfn; 61 struct percpu_counter vm_committed_as; 62 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 63 int sysctl_overcommit_ratio = 50; /* default is 50% */ 64 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 65 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; 66 int heap_stack_gap = 0; 67 68 atomic_long_t mmap_pages_allocated; 69 70 /* 71 * The global memory commitment made in the system can be a metric 72 * that can be used to drive ballooning decisions when Linux is hosted 73 * as a guest. On Hyper-V, the host implements a policy engine for dynamically 74 * balancing memory across competing virtual machines that are hosted. 75 * Several metrics drive this policy engine including the guest reported 76 * memory commitment. 77 */ 78 unsigned long vm_memory_committed(void) 79 { 80 return percpu_counter_read_positive(&vm_committed_as); 81 } 82 83 EXPORT_SYMBOL_GPL(vm_memory_committed); 84 85 EXPORT_SYMBOL(mem_map); 86 EXPORT_SYMBOL(num_physpages); 87 88 /* list of mapped, potentially shareable regions */ 89 static struct kmem_cache *vm_region_jar; 90 struct rb_root nommu_region_tree = RB_ROOT; 91 DECLARE_RWSEM(nommu_region_sem); 92 93 const struct vm_operations_struct generic_file_vm_ops = { 94 }; 95 96 /* 97 * Return the total memory allocated for this pointer, not 98 * just what the caller asked for. 99 * 100 * Doesn't have to be accurate, i.e. may have races. 101 */ 102 unsigned int kobjsize(const void *objp) 103 { 104 struct page *page; 105 106 /* 107 * If the object we have should not have ksize performed on it, 108 * return size of 0 109 */ 110 if (!objp || !virt_addr_valid(objp)) 111 return 0; 112 113 page = virt_to_head_page(objp); 114 115 /* 116 * If the allocator sets PageSlab, we know the pointer came from 117 * kmalloc(). 118 */ 119 if (PageSlab(page)) 120 return ksize(objp); 121 122 /* 123 * If it's not a compound page, see if we have a matching VMA 124 * region. This test is intentionally done in reverse order, 125 * so if there's no VMA, we still fall through and hand back 126 * PAGE_SIZE for 0-order pages. 127 */ 128 if (!PageCompound(page)) { 129 struct vm_area_struct *vma; 130 131 vma = find_vma(current->mm, (unsigned long)objp); 132 if (vma) 133 return vma->vm_end - vma->vm_start; 134 } 135 136 /* 137 * The ksize() function is only guaranteed to work for pointers 138 * returned by kmalloc(). So handle arbitrary pointers here. 139 */ 140 return PAGE_SIZE << compound_order(page); 141 } 142 143 long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 144 unsigned long start, unsigned long nr_pages, 145 unsigned int foll_flags, struct page **pages, 146 struct vm_area_struct **vmas, int *nonblocking) 147 { 148 struct vm_area_struct *vma; 149 unsigned long vm_flags; 150 int i; 151 152 /* calculate required read or write permissions. 153 * If FOLL_FORCE is set, we only require the "MAY" flags. 154 */ 155 vm_flags = (foll_flags & FOLL_WRITE) ? 156 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 157 vm_flags &= (foll_flags & FOLL_FORCE) ? 158 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 159 160 for (i = 0; i < nr_pages; i++) { 161 vma = find_vma(mm, start); 162 if (!vma) 163 goto finish_or_fault; 164 165 /* protect what we can, including chardevs */ 166 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || 167 !(vm_flags & vma->vm_flags)) 168 goto finish_or_fault; 169 170 if (pages) { 171 pages[i] = virt_to_page(start); 172 if (pages[i]) 173 page_cache_get(pages[i]); 174 } 175 if (vmas) 176 vmas[i] = vma; 177 start = (start + PAGE_SIZE) & PAGE_MASK; 178 } 179 180 return i; 181 182 finish_or_fault: 183 return i ? : -EFAULT; 184 } 185 186 /* 187 * get a list of pages in an address range belonging to the specified process 188 * and indicate the VMA that covers each page 189 * - this is potentially dodgy as we may end incrementing the page count of a 190 * slab page or a secondary page from a compound page 191 * - don't permit access to VMAs that don't support it, such as I/O mappings 192 */ 193 long get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 194 unsigned long start, unsigned long nr_pages, 195 int write, int force, struct page **pages, 196 struct vm_area_struct **vmas) 197 { 198 int flags = 0; 199 200 if (write) 201 flags |= FOLL_WRITE; 202 if (force) 203 flags |= FOLL_FORCE; 204 205 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 206 NULL); 207 } 208 EXPORT_SYMBOL(get_user_pages); 209 210 /** 211 * follow_pfn - look up PFN at a user virtual address 212 * @vma: memory mapping 213 * @address: user virtual address 214 * @pfn: location to store found PFN 215 * 216 * Only IO mappings and raw PFN mappings are allowed. 217 * 218 * Returns zero and the pfn at @pfn on success, -ve otherwise. 219 */ 220 int follow_pfn(struct vm_area_struct *vma, unsigned long address, 221 unsigned long *pfn) 222 { 223 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 224 return -EINVAL; 225 226 *pfn = address >> PAGE_SHIFT; 227 return 0; 228 } 229 EXPORT_SYMBOL(follow_pfn); 230 231 DEFINE_RWLOCK(vmlist_lock); 232 struct vm_struct *vmlist; 233 234 void vfree(const void *addr) 235 { 236 kfree(addr); 237 } 238 EXPORT_SYMBOL(vfree); 239 240 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 241 { 242 /* 243 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() 244 * returns only a logical address. 245 */ 246 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 247 } 248 EXPORT_SYMBOL(__vmalloc); 249 250 void *vmalloc_user(unsigned long size) 251 { 252 void *ret; 253 254 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 255 PAGE_KERNEL); 256 if (ret) { 257 struct vm_area_struct *vma; 258 259 down_write(¤t->mm->mmap_sem); 260 vma = find_vma(current->mm, (unsigned long)ret); 261 if (vma) 262 vma->vm_flags |= VM_USERMAP; 263 up_write(¤t->mm->mmap_sem); 264 } 265 266 return ret; 267 } 268 EXPORT_SYMBOL(vmalloc_user); 269 270 struct page *vmalloc_to_page(const void *addr) 271 { 272 return virt_to_page(addr); 273 } 274 EXPORT_SYMBOL(vmalloc_to_page); 275 276 unsigned long vmalloc_to_pfn(const void *addr) 277 { 278 return page_to_pfn(virt_to_page(addr)); 279 } 280 EXPORT_SYMBOL(vmalloc_to_pfn); 281 282 long vread(char *buf, char *addr, unsigned long count) 283 { 284 memcpy(buf, addr, count); 285 return count; 286 } 287 288 long vwrite(char *buf, char *addr, unsigned long count) 289 { 290 /* Don't allow overflow */ 291 if ((unsigned long) addr + count < count) 292 count = -(unsigned long) addr; 293 294 memcpy(addr, buf, count); 295 return(count); 296 } 297 298 /* 299 * vmalloc - allocate virtually continguos memory 300 * 301 * @size: allocation size 302 * 303 * Allocate enough pages to cover @size from the page level 304 * allocator and map them into continguos kernel virtual space. 305 * 306 * For tight control over page level allocator and protection flags 307 * use __vmalloc() instead. 308 */ 309 void *vmalloc(unsigned long size) 310 { 311 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 312 } 313 EXPORT_SYMBOL(vmalloc); 314 315 /* 316 * vzalloc - allocate virtually continguos memory with zero fill 317 * 318 * @size: allocation size 319 * 320 * Allocate enough pages to cover @size from the page level 321 * allocator and map them into continguos kernel virtual space. 322 * The memory allocated is set to zero. 323 * 324 * For tight control over page level allocator and protection flags 325 * use __vmalloc() instead. 326 */ 327 void *vzalloc(unsigned long size) 328 { 329 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 330 PAGE_KERNEL); 331 } 332 EXPORT_SYMBOL(vzalloc); 333 334 /** 335 * vmalloc_node - allocate memory on a specific node 336 * @size: allocation size 337 * @node: numa node 338 * 339 * Allocate enough pages to cover @size from the page level 340 * allocator and map them into contiguous kernel virtual space. 341 * 342 * For tight control over page level allocator and protection flags 343 * use __vmalloc() instead. 344 */ 345 void *vmalloc_node(unsigned long size, int node) 346 { 347 return vmalloc(size); 348 } 349 EXPORT_SYMBOL(vmalloc_node); 350 351 /** 352 * vzalloc_node - allocate memory on a specific node with zero fill 353 * @size: allocation size 354 * @node: numa node 355 * 356 * Allocate enough pages to cover @size from the page level 357 * allocator and map them into contiguous kernel virtual space. 358 * The memory allocated is set to zero. 359 * 360 * For tight control over page level allocator and protection flags 361 * use __vmalloc() instead. 362 */ 363 void *vzalloc_node(unsigned long size, int node) 364 { 365 return vzalloc(size); 366 } 367 EXPORT_SYMBOL(vzalloc_node); 368 369 #ifndef PAGE_KERNEL_EXEC 370 # define PAGE_KERNEL_EXEC PAGE_KERNEL 371 #endif 372 373 /** 374 * vmalloc_exec - allocate virtually contiguous, executable memory 375 * @size: allocation size 376 * 377 * Kernel-internal function to allocate enough pages to cover @size 378 * the page level allocator and map them into contiguous and 379 * executable kernel virtual space. 380 * 381 * For tight control over page level allocator and protection flags 382 * use __vmalloc() instead. 383 */ 384 385 void *vmalloc_exec(unsigned long size) 386 { 387 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); 388 } 389 390 /** 391 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) 392 * @size: allocation size 393 * 394 * Allocate enough 32bit PA addressable pages to cover @size from the 395 * page level allocator and map them into continguos kernel virtual space. 396 */ 397 void *vmalloc_32(unsigned long size) 398 { 399 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 400 } 401 EXPORT_SYMBOL(vmalloc_32); 402 403 /** 404 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory 405 * @size: allocation size 406 * 407 * The resulting memory area is 32bit addressable and zeroed so it can be 408 * mapped to userspace without leaking data. 409 * 410 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to 411 * remap_vmalloc_range() are permissible. 412 */ 413 void *vmalloc_32_user(unsigned long size) 414 { 415 /* 416 * We'll have to sort out the ZONE_DMA bits for 64-bit, 417 * but for now this can simply use vmalloc_user() directly. 418 */ 419 return vmalloc_user(size); 420 } 421 EXPORT_SYMBOL(vmalloc_32_user); 422 423 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 424 { 425 BUG(); 426 return NULL; 427 } 428 EXPORT_SYMBOL(vmap); 429 430 void vunmap(const void *addr) 431 { 432 BUG(); 433 } 434 EXPORT_SYMBOL(vunmap); 435 436 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) 437 { 438 BUG(); 439 return NULL; 440 } 441 EXPORT_SYMBOL(vm_map_ram); 442 443 void vm_unmap_ram(const void *mem, unsigned int count) 444 { 445 BUG(); 446 } 447 EXPORT_SYMBOL(vm_unmap_ram); 448 449 void vm_unmap_aliases(void) 450 { 451 } 452 EXPORT_SYMBOL_GPL(vm_unmap_aliases); 453 454 /* 455 * Implement a stub for vmalloc_sync_all() if the architecture chose not to 456 * have one. 457 */ 458 void __attribute__((weak)) vmalloc_sync_all(void) 459 { 460 } 461 462 /** 463 * alloc_vm_area - allocate a range of kernel address space 464 * @size: size of the area 465 * 466 * Returns: NULL on failure, vm_struct on success 467 * 468 * This function reserves a range of kernel address space, and 469 * allocates pagetables to map that range. No actual mappings 470 * are created. If the kernel address space is not shared 471 * between processes, it syncs the pagetable across all 472 * processes. 473 */ 474 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes) 475 { 476 BUG(); 477 return NULL; 478 } 479 EXPORT_SYMBOL_GPL(alloc_vm_area); 480 481 void free_vm_area(struct vm_struct *area) 482 { 483 BUG(); 484 } 485 EXPORT_SYMBOL_GPL(free_vm_area); 486 487 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 488 struct page *page) 489 { 490 return -EINVAL; 491 } 492 EXPORT_SYMBOL(vm_insert_page); 493 494 /* 495 * sys_brk() for the most part doesn't need the global kernel 496 * lock, except when an application is doing something nasty 497 * like trying to un-brk an area that has already been mapped 498 * to a regular file. in this case, the unmapping will need 499 * to invoke file system routines that need the global lock. 500 */ 501 SYSCALL_DEFINE1(brk, unsigned long, brk) 502 { 503 struct mm_struct *mm = current->mm; 504 505 if (brk < mm->start_brk || brk > mm->context.end_brk) 506 return mm->brk; 507 508 if (mm->brk == brk) 509 return mm->brk; 510 511 /* 512 * Always allow shrinking brk 513 */ 514 if (brk <= mm->brk) { 515 mm->brk = brk; 516 return brk; 517 } 518 519 /* 520 * Ok, looks good - let it rip. 521 */ 522 flush_icache_range(mm->brk, brk); 523 return mm->brk = brk; 524 } 525 526 /* 527 * initialise the VMA and region record slabs 528 */ 529 void __init mmap_init(void) 530 { 531 int ret; 532 533 ret = percpu_counter_init(&vm_committed_as, 0); 534 VM_BUG_ON(ret); 535 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC); 536 } 537 538 /* 539 * validate the region tree 540 * - the caller must hold the region lock 541 */ 542 #ifdef CONFIG_DEBUG_NOMMU_REGIONS 543 static noinline void validate_nommu_regions(void) 544 { 545 struct vm_region *region, *last; 546 struct rb_node *p, *lastp; 547 548 lastp = rb_first(&nommu_region_tree); 549 if (!lastp) 550 return; 551 552 last = rb_entry(lastp, struct vm_region, vm_rb); 553 BUG_ON(unlikely(last->vm_end <= last->vm_start)); 554 BUG_ON(unlikely(last->vm_top < last->vm_end)); 555 556 while ((p = rb_next(lastp))) { 557 region = rb_entry(p, struct vm_region, vm_rb); 558 last = rb_entry(lastp, struct vm_region, vm_rb); 559 560 BUG_ON(unlikely(region->vm_end <= region->vm_start)); 561 BUG_ON(unlikely(region->vm_top < region->vm_end)); 562 BUG_ON(unlikely(region->vm_start < last->vm_top)); 563 564 lastp = p; 565 } 566 } 567 #else 568 static void validate_nommu_regions(void) 569 { 570 } 571 #endif 572 573 /* 574 * add a region into the global tree 575 */ 576 static void add_nommu_region(struct vm_region *region) 577 { 578 struct vm_region *pregion; 579 struct rb_node **p, *parent; 580 581 validate_nommu_regions(); 582 583 parent = NULL; 584 p = &nommu_region_tree.rb_node; 585 while (*p) { 586 parent = *p; 587 pregion = rb_entry(parent, struct vm_region, vm_rb); 588 if (region->vm_start < pregion->vm_start) 589 p = &(*p)->rb_left; 590 else if (region->vm_start > pregion->vm_start) 591 p = &(*p)->rb_right; 592 else if (pregion == region) 593 return; 594 else 595 BUG(); 596 } 597 598 rb_link_node(®ion->vm_rb, parent, p); 599 rb_insert_color(®ion->vm_rb, &nommu_region_tree); 600 601 validate_nommu_regions(); 602 } 603 604 /* 605 * delete a region from the global tree 606 */ 607 static void delete_nommu_region(struct vm_region *region) 608 { 609 BUG_ON(!nommu_region_tree.rb_node); 610 611 validate_nommu_regions(); 612 rb_erase(®ion->vm_rb, &nommu_region_tree); 613 validate_nommu_regions(); 614 } 615 616 /* 617 * free a contiguous series of pages 618 */ 619 static void free_page_series(unsigned long from, unsigned long to) 620 { 621 for (; from < to; from += PAGE_SIZE) { 622 struct page *page = virt_to_page(from); 623 624 kdebug("- free %lx", from); 625 atomic_long_dec(&mmap_pages_allocated); 626 if (page_count(page) != 1) 627 kdebug("free page %p: refcount not one: %d", 628 page, page_count(page)); 629 put_page(page); 630 } 631 } 632 633 /* 634 * release a reference to a region 635 * - the caller must hold the region semaphore for writing, which this releases 636 * - the region may not have been added to the tree yet, in which case vm_top 637 * will equal vm_start 638 */ 639 static void __put_nommu_region(struct vm_region *region) 640 __releases(nommu_region_sem) 641 { 642 kenter("%p{%d}", region, region->vm_usage); 643 644 BUG_ON(!nommu_region_tree.rb_node); 645 646 if (--region->vm_usage == 0) { 647 if (region->vm_top > region->vm_start) 648 delete_nommu_region(region); 649 up_write(&nommu_region_sem); 650 651 if (region->vm_file) 652 fput(region->vm_file); 653 654 /* IO memory and memory shared directly out of the pagecache 655 * from ramfs/tmpfs mustn't be released here */ 656 if (region->vm_flags & VM_MAPPED_COPY) { 657 kdebug("free series"); 658 free_page_series(region->vm_start, region->vm_top); 659 } 660 kmem_cache_free(vm_region_jar, region); 661 } else { 662 up_write(&nommu_region_sem); 663 } 664 } 665 666 /* 667 * release a reference to a region 668 */ 669 static void put_nommu_region(struct vm_region *region) 670 { 671 down_write(&nommu_region_sem); 672 __put_nommu_region(region); 673 } 674 675 /* 676 * update protection on a vma 677 */ 678 static void protect_vma(struct vm_area_struct *vma, unsigned long flags) 679 { 680 #ifdef CONFIG_MPU 681 struct mm_struct *mm = vma->vm_mm; 682 long start = vma->vm_start & PAGE_MASK; 683 while (start < vma->vm_end) { 684 protect_page(mm, start, flags); 685 start += PAGE_SIZE; 686 } 687 update_protections(mm); 688 #endif 689 } 690 691 /* 692 * add a VMA into a process's mm_struct in the appropriate place in the list 693 * and tree and add to the address space's page tree also if not an anonymous 694 * page 695 * - should be called with mm->mmap_sem held writelocked 696 */ 697 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) 698 { 699 struct vm_area_struct *pvma, *prev; 700 struct address_space *mapping; 701 struct rb_node **p, *parent, *rb_prev; 702 703 kenter(",%p", vma); 704 705 BUG_ON(!vma->vm_region); 706 707 mm->map_count++; 708 vma->vm_mm = mm; 709 710 protect_vma(vma, vma->vm_flags); 711 712 /* add the VMA to the mapping */ 713 if (vma->vm_file) { 714 mapping = vma->vm_file->f_mapping; 715 716 mutex_lock(&mapping->i_mmap_mutex); 717 flush_dcache_mmap_lock(mapping); 718 vma_interval_tree_insert(vma, &mapping->i_mmap); 719 flush_dcache_mmap_unlock(mapping); 720 mutex_unlock(&mapping->i_mmap_mutex); 721 } 722 723 /* add the VMA to the tree */ 724 parent = rb_prev = NULL; 725 p = &mm->mm_rb.rb_node; 726 while (*p) { 727 parent = *p; 728 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 729 730 /* sort by: start addr, end addr, VMA struct addr in that order 731 * (the latter is necessary as we may get identical VMAs) */ 732 if (vma->vm_start < pvma->vm_start) 733 p = &(*p)->rb_left; 734 else if (vma->vm_start > pvma->vm_start) { 735 rb_prev = parent; 736 p = &(*p)->rb_right; 737 } else if (vma->vm_end < pvma->vm_end) 738 p = &(*p)->rb_left; 739 else if (vma->vm_end > pvma->vm_end) { 740 rb_prev = parent; 741 p = &(*p)->rb_right; 742 } else if (vma < pvma) 743 p = &(*p)->rb_left; 744 else if (vma > pvma) { 745 rb_prev = parent; 746 p = &(*p)->rb_right; 747 } else 748 BUG(); 749 } 750 751 rb_link_node(&vma->vm_rb, parent, p); 752 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 753 754 /* add VMA to the VMA list also */ 755 prev = NULL; 756 if (rb_prev) 757 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 758 759 __vma_link_list(mm, vma, prev, parent); 760 } 761 762 /* 763 * delete a VMA from its owning mm_struct and address space 764 */ 765 static void delete_vma_from_mm(struct vm_area_struct *vma) 766 { 767 struct address_space *mapping; 768 struct mm_struct *mm = vma->vm_mm; 769 770 kenter("%p", vma); 771 772 protect_vma(vma, 0); 773 774 mm->map_count--; 775 if (mm->mmap_cache == vma) 776 mm->mmap_cache = NULL; 777 778 /* remove the VMA from the mapping */ 779 if (vma->vm_file) { 780 mapping = vma->vm_file->f_mapping; 781 782 mutex_lock(&mapping->i_mmap_mutex); 783 flush_dcache_mmap_lock(mapping); 784 vma_interval_tree_remove(vma, &mapping->i_mmap); 785 flush_dcache_mmap_unlock(mapping); 786 mutex_unlock(&mapping->i_mmap_mutex); 787 } 788 789 /* remove from the MM's tree and list */ 790 rb_erase(&vma->vm_rb, &mm->mm_rb); 791 792 if (vma->vm_prev) 793 vma->vm_prev->vm_next = vma->vm_next; 794 else 795 mm->mmap = vma->vm_next; 796 797 if (vma->vm_next) 798 vma->vm_next->vm_prev = vma->vm_prev; 799 } 800 801 /* 802 * destroy a VMA record 803 */ 804 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) 805 { 806 kenter("%p", vma); 807 if (vma->vm_ops && vma->vm_ops->close) 808 vma->vm_ops->close(vma); 809 if (vma->vm_file) 810 fput(vma->vm_file); 811 put_nommu_region(vma->vm_region); 812 kmem_cache_free(vm_area_cachep, vma); 813 } 814 815 /* 816 * look up the first VMA in which addr resides, NULL if none 817 * - should be called with mm->mmap_sem at least held readlocked 818 */ 819 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 820 { 821 struct vm_area_struct *vma; 822 823 /* check the cache first */ 824 vma = mm->mmap_cache; 825 if (vma && vma->vm_start <= addr && vma->vm_end > addr) 826 return vma; 827 828 /* trawl the list (there may be multiple mappings in which addr 829 * resides) */ 830 for (vma = mm->mmap; vma; vma = vma->vm_next) { 831 if (vma->vm_start > addr) 832 return NULL; 833 if (vma->vm_end > addr) { 834 mm->mmap_cache = vma; 835 return vma; 836 } 837 } 838 839 return NULL; 840 } 841 EXPORT_SYMBOL(find_vma); 842 843 /* 844 * find a VMA 845 * - we don't extend stack VMAs under NOMMU conditions 846 */ 847 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 848 { 849 return find_vma(mm, addr); 850 } 851 852 /* 853 * expand a stack to a given address 854 * - not supported under NOMMU conditions 855 */ 856 int expand_stack(struct vm_area_struct *vma, unsigned long address) 857 { 858 return -ENOMEM; 859 } 860 861 /* 862 * look up the first VMA exactly that exactly matches addr 863 * - should be called with mm->mmap_sem at least held readlocked 864 */ 865 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 866 unsigned long addr, 867 unsigned long len) 868 { 869 struct vm_area_struct *vma; 870 unsigned long end = addr + len; 871 872 /* check the cache first */ 873 vma = mm->mmap_cache; 874 if (vma && vma->vm_start == addr && vma->vm_end == end) 875 return vma; 876 877 /* trawl the list (there may be multiple mappings in which addr 878 * resides) */ 879 for (vma = mm->mmap; vma; vma = vma->vm_next) { 880 if (vma->vm_start < addr) 881 continue; 882 if (vma->vm_start > addr) 883 return NULL; 884 if (vma->vm_end == end) { 885 mm->mmap_cache = vma; 886 return vma; 887 } 888 } 889 890 return NULL; 891 } 892 893 /* 894 * determine whether a mapping should be permitted and, if so, what sort of 895 * mapping we're capable of supporting 896 */ 897 static int validate_mmap_request(struct file *file, 898 unsigned long addr, 899 unsigned long len, 900 unsigned long prot, 901 unsigned long flags, 902 unsigned long pgoff, 903 unsigned long *_capabilities) 904 { 905 unsigned long capabilities, rlen; 906 int ret; 907 908 /* do the simple checks first */ 909 if (flags & MAP_FIXED) { 910 printk(KERN_DEBUG 911 "%d: Can't do fixed-address/overlay mmap of RAM\n", 912 current->pid); 913 return -EINVAL; 914 } 915 916 if ((flags & MAP_TYPE) != MAP_PRIVATE && 917 (flags & MAP_TYPE) != MAP_SHARED) 918 return -EINVAL; 919 920 if (!len) 921 return -EINVAL; 922 923 /* Careful about overflows.. */ 924 rlen = PAGE_ALIGN(len); 925 if (!rlen || rlen > TASK_SIZE) 926 return -ENOMEM; 927 928 /* offset overflow? */ 929 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) 930 return -EOVERFLOW; 931 932 if (file) { 933 /* validate file mapping requests */ 934 struct address_space *mapping; 935 936 /* files must support mmap */ 937 if (!file->f_op || !file->f_op->mmap) 938 return -ENODEV; 939 940 /* work out if what we've got could possibly be shared 941 * - we support chardevs that provide their own "memory" 942 * - we support files/blockdevs that are memory backed 943 */ 944 mapping = file->f_mapping; 945 if (!mapping) 946 mapping = file_inode(file)->i_mapping; 947 948 capabilities = 0; 949 if (mapping && mapping->backing_dev_info) 950 capabilities = mapping->backing_dev_info->capabilities; 951 952 if (!capabilities) { 953 /* no explicit capabilities set, so assume some 954 * defaults */ 955 switch (file_inode(file)->i_mode & S_IFMT) { 956 case S_IFREG: 957 case S_IFBLK: 958 capabilities = BDI_CAP_MAP_COPY; 959 break; 960 961 case S_IFCHR: 962 capabilities = 963 BDI_CAP_MAP_DIRECT | 964 BDI_CAP_READ_MAP | 965 BDI_CAP_WRITE_MAP; 966 break; 967 968 default: 969 return -EINVAL; 970 } 971 } 972 973 /* eliminate any capabilities that we can't support on this 974 * device */ 975 if (!file->f_op->get_unmapped_area) 976 capabilities &= ~BDI_CAP_MAP_DIRECT; 977 if (!file->f_op->read) 978 capabilities &= ~BDI_CAP_MAP_COPY; 979 980 /* The file shall have been opened with read permission. */ 981 if (!(file->f_mode & FMODE_READ)) 982 return -EACCES; 983 984 if (flags & MAP_SHARED) { 985 /* do checks for writing, appending and locking */ 986 if ((prot & PROT_WRITE) && 987 !(file->f_mode & FMODE_WRITE)) 988 return -EACCES; 989 990 if (IS_APPEND(file_inode(file)) && 991 (file->f_mode & FMODE_WRITE)) 992 return -EACCES; 993 994 if (locks_verify_locked(file_inode(file))) 995 return -EAGAIN; 996 997 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 998 return -ENODEV; 999 1000 /* we mustn't privatise shared mappings */ 1001 capabilities &= ~BDI_CAP_MAP_COPY; 1002 } 1003 else { 1004 /* we're going to read the file into private memory we 1005 * allocate */ 1006 if (!(capabilities & BDI_CAP_MAP_COPY)) 1007 return -ENODEV; 1008 1009 /* we don't permit a private writable mapping to be 1010 * shared with the backing device */ 1011 if (prot & PROT_WRITE) 1012 capabilities &= ~BDI_CAP_MAP_DIRECT; 1013 } 1014 1015 if (capabilities & BDI_CAP_MAP_DIRECT) { 1016 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 1017 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 1018 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 1019 ) { 1020 capabilities &= ~BDI_CAP_MAP_DIRECT; 1021 if (flags & MAP_SHARED) { 1022 printk(KERN_WARNING 1023 "MAP_SHARED not completely supported on !MMU\n"); 1024 return -EINVAL; 1025 } 1026 } 1027 } 1028 1029 /* handle executable mappings and implied executable 1030 * mappings */ 1031 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1032 if (prot & PROT_EXEC) 1033 return -EPERM; 1034 } 1035 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 1036 /* handle implication of PROT_EXEC by PROT_READ */ 1037 if (current->personality & READ_IMPLIES_EXEC) { 1038 if (capabilities & BDI_CAP_EXEC_MAP) 1039 prot |= PROT_EXEC; 1040 } 1041 } 1042 else if ((prot & PROT_READ) && 1043 (prot & PROT_EXEC) && 1044 !(capabilities & BDI_CAP_EXEC_MAP) 1045 ) { 1046 /* backing file is not executable, try to copy */ 1047 capabilities &= ~BDI_CAP_MAP_DIRECT; 1048 } 1049 } 1050 else { 1051 /* anonymous mappings are always memory backed and can be 1052 * privately mapped 1053 */ 1054 capabilities = BDI_CAP_MAP_COPY; 1055 1056 /* handle PROT_EXEC implication by PROT_READ */ 1057 if ((prot & PROT_READ) && 1058 (current->personality & READ_IMPLIES_EXEC)) 1059 prot |= PROT_EXEC; 1060 } 1061 1062 /* allow the security API to have its say */ 1063 ret = security_mmap_addr(addr); 1064 if (ret < 0) 1065 return ret; 1066 1067 /* looks okay */ 1068 *_capabilities = capabilities; 1069 return 0; 1070 } 1071 1072 /* 1073 * we've determined that we can make the mapping, now translate what we 1074 * now know into VMA flags 1075 */ 1076 static unsigned long determine_vm_flags(struct file *file, 1077 unsigned long prot, 1078 unsigned long flags, 1079 unsigned long capabilities) 1080 { 1081 unsigned long vm_flags; 1082 1083 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 1084 /* vm_flags |= mm->def_flags; */ 1085 1086 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 1087 /* attempt to share read-only copies of mapped file chunks */ 1088 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1089 if (file && !(prot & PROT_WRITE)) 1090 vm_flags |= VM_MAYSHARE; 1091 } else { 1092 /* overlay a shareable mapping on the backing device or inode 1093 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 1094 * romfs/cramfs */ 1095 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS); 1096 if (flags & MAP_SHARED) 1097 vm_flags |= VM_SHARED; 1098 } 1099 1100 /* refuse to let anyone share private mappings with this process if 1101 * it's being traced - otherwise breakpoints set in it may interfere 1102 * with another untraced process 1103 */ 1104 if ((flags & MAP_PRIVATE) && current->ptrace) 1105 vm_flags &= ~VM_MAYSHARE; 1106 1107 return vm_flags; 1108 } 1109 1110 /* 1111 * set up a shared mapping on a file (the driver or filesystem provides and 1112 * pins the storage) 1113 */ 1114 static int do_mmap_shared_file(struct vm_area_struct *vma) 1115 { 1116 int ret; 1117 1118 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1119 if (ret == 0) { 1120 vma->vm_region->vm_top = vma->vm_region->vm_end; 1121 return 0; 1122 } 1123 if (ret != -ENOSYS) 1124 return ret; 1125 1126 /* getting -ENOSYS indicates that direct mmap isn't possible (as 1127 * opposed to tried but failed) so we can only give a suitable error as 1128 * it's not possible to make a private copy if MAP_SHARED was given */ 1129 return -ENODEV; 1130 } 1131 1132 /* 1133 * set up a private mapping or an anonymous shared mapping 1134 */ 1135 static int do_mmap_private(struct vm_area_struct *vma, 1136 struct vm_region *region, 1137 unsigned long len, 1138 unsigned long capabilities) 1139 { 1140 struct page *pages; 1141 unsigned long total, point, n; 1142 void *base; 1143 int ret, order; 1144 1145 /* invoke the file's mapping function so that it can keep track of 1146 * shared mappings on devices or memory 1147 * - VM_MAYSHARE will be set if it may attempt to share 1148 */ 1149 if (capabilities & BDI_CAP_MAP_DIRECT) { 1150 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1151 if (ret == 0) { 1152 /* shouldn't return success if we're not sharing */ 1153 BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); 1154 vma->vm_region->vm_top = vma->vm_region->vm_end; 1155 return 0; 1156 } 1157 if (ret != -ENOSYS) 1158 return ret; 1159 1160 /* getting an ENOSYS error indicates that direct mmap isn't 1161 * possible (as opposed to tried but failed) so we'll try to 1162 * make a private copy of the data and map that instead */ 1163 } 1164 1165 1166 /* allocate some memory to hold the mapping 1167 * - note that this may not return a page-aligned address if the object 1168 * we're allocating is smaller than a page 1169 */ 1170 order = get_order(len); 1171 kdebug("alloc order %d for %lx", order, len); 1172 1173 pages = alloc_pages(GFP_KERNEL, order); 1174 if (!pages) 1175 goto enomem; 1176 1177 total = 1 << order; 1178 atomic_long_add(total, &mmap_pages_allocated); 1179 1180 point = len >> PAGE_SHIFT; 1181 1182 /* we allocated a power-of-2 sized page set, so we may want to trim off 1183 * the excess */ 1184 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) { 1185 while (total > point) { 1186 order = ilog2(total - point); 1187 n = 1 << order; 1188 kdebug("shave %lu/%lu @%lu", n, total - point, total); 1189 atomic_long_sub(n, &mmap_pages_allocated); 1190 total -= n; 1191 set_page_refcounted(pages + total); 1192 __free_pages(pages + total, order); 1193 } 1194 } 1195 1196 for (point = 1; point < total; point++) 1197 set_page_refcounted(&pages[point]); 1198 1199 base = page_address(pages); 1200 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; 1201 region->vm_start = (unsigned long) base; 1202 region->vm_end = region->vm_start + len; 1203 region->vm_top = region->vm_start + (total << PAGE_SHIFT); 1204 1205 vma->vm_start = region->vm_start; 1206 vma->vm_end = region->vm_start + len; 1207 1208 if (vma->vm_file) { 1209 /* read the contents of a file into the copy */ 1210 mm_segment_t old_fs; 1211 loff_t fpos; 1212 1213 fpos = vma->vm_pgoff; 1214 fpos <<= PAGE_SHIFT; 1215 1216 old_fs = get_fs(); 1217 set_fs(KERNEL_DS); 1218 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos); 1219 set_fs(old_fs); 1220 1221 if (ret < 0) 1222 goto error_free; 1223 1224 /* clear the last little bit */ 1225 if (ret < len) 1226 memset(base + ret, 0, len - ret); 1227 1228 } 1229 1230 return 0; 1231 1232 error_free: 1233 free_page_series(region->vm_start, region->vm_top); 1234 region->vm_start = vma->vm_start = 0; 1235 region->vm_end = vma->vm_end = 0; 1236 region->vm_top = 0; 1237 return ret; 1238 1239 enomem: 1240 printk("Allocation of length %lu from process %d (%s) failed\n", 1241 len, current->pid, current->comm); 1242 show_free_areas(0); 1243 return -ENOMEM; 1244 } 1245 1246 /* 1247 * handle mapping creation for uClinux 1248 */ 1249 unsigned long do_mmap_pgoff(struct file *file, 1250 unsigned long addr, 1251 unsigned long len, 1252 unsigned long prot, 1253 unsigned long flags, 1254 unsigned long pgoff, 1255 unsigned long *populate) 1256 { 1257 struct vm_area_struct *vma; 1258 struct vm_region *region; 1259 struct rb_node *rb; 1260 unsigned long capabilities, vm_flags, result; 1261 int ret; 1262 1263 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff); 1264 1265 *populate = 0; 1266 1267 /* decide whether we should attempt the mapping, and if so what sort of 1268 * mapping */ 1269 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 1270 &capabilities); 1271 if (ret < 0) { 1272 kleave(" = %d [val]", ret); 1273 return ret; 1274 } 1275 1276 /* we ignore the address hint */ 1277 addr = 0; 1278 len = PAGE_ALIGN(len); 1279 1280 /* we've determined that we can make the mapping, now translate what we 1281 * now know into VMA flags */ 1282 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 1283 1284 /* we're going to need to record the mapping */ 1285 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); 1286 if (!region) 1287 goto error_getting_region; 1288 1289 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1290 if (!vma) 1291 goto error_getting_vma; 1292 1293 region->vm_usage = 1; 1294 region->vm_flags = vm_flags; 1295 region->vm_pgoff = pgoff; 1296 1297 INIT_LIST_HEAD(&vma->anon_vma_chain); 1298 vma->vm_flags = vm_flags; 1299 vma->vm_pgoff = pgoff; 1300 1301 if (file) { 1302 region->vm_file = get_file(file); 1303 vma->vm_file = get_file(file); 1304 } 1305 1306 down_write(&nommu_region_sem); 1307 1308 /* if we want to share, we need to check for regions created by other 1309 * mmap() calls that overlap with our proposed mapping 1310 * - we can only share with a superset match on most regular files 1311 * - shared mappings on character devices and memory backed files are 1312 * permitted to overlap inexactly as far as we are concerned for in 1313 * these cases, sharing is handled in the driver or filesystem rather 1314 * than here 1315 */ 1316 if (vm_flags & VM_MAYSHARE) { 1317 struct vm_region *pregion; 1318 unsigned long pglen, rpglen, pgend, rpgend, start; 1319 1320 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1321 pgend = pgoff + pglen; 1322 1323 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { 1324 pregion = rb_entry(rb, struct vm_region, vm_rb); 1325 1326 if (!(pregion->vm_flags & VM_MAYSHARE)) 1327 continue; 1328 1329 /* search for overlapping mappings on the same file */ 1330 if (file_inode(pregion->vm_file) != 1331 file_inode(file)) 1332 continue; 1333 1334 if (pregion->vm_pgoff >= pgend) 1335 continue; 1336 1337 rpglen = pregion->vm_end - pregion->vm_start; 1338 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1339 rpgend = pregion->vm_pgoff + rpglen; 1340 if (pgoff >= rpgend) 1341 continue; 1342 1343 /* handle inexactly overlapping matches between 1344 * mappings */ 1345 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && 1346 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { 1347 /* new mapping is not a subset of the region */ 1348 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 1349 goto sharing_violation; 1350 continue; 1351 } 1352 1353 /* we've found a region we can share */ 1354 pregion->vm_usage++; 1355 vma->vm_region = pregion; 1356 start = pregion->vm_start; 1357 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; 1358 vma->vm_start = start; 1359 vma->vm_end = start + len; 1360 1361 if (pregion->vm_flags & VM_MAPPED_COPY) { 1362 kdebug("share copy"); 1363 vma->vm_flags |= VM_MAPPED_COPY; 1364 } else { 1365 kdebug("share mmap"); 1366 ret = do_mmap_shared_file(vma); 1367 if (ret < 0) { 1368 vma->vm_region = NULL; 1369 vma->vm_start = 0; 1370 vma->vm_end = 0; 1371 pregion->vm_usage--; 1372 pregion = NULL; 1373 goto error_just_free; 1374 } 1375 } 1376 fput(region->vm_file); 1377 kmem_cache_free(vm_region_jar, region); 1378 region = pregion; 1379 result = start; 1380 goto share; 1381 } 1382 1383 /* obtain the address at which to make a shared mapping 1384 * - this is the hook for quasi-memory character devices to 1385 * tell us the location of a shared mapping 1386 */ 1387 if (capabilities & BDI_CAP_MAP_DIRECT) { 1388 addr = file->f_op->get_unmapped_area(file, addr, len, 1389 pgoff, flags); 1390 if (IS_ERR_VALUE(addr)) { 1391 ret = addr; 1392 if (ret != -ENOSYS) 1393 goto error_just_free; 1394 1395 /* the driver refused to tell us where to site 1396 * the mapping so we'll have to attempt to copy 1397 * it */ 1398 ret = -ENODEV; 1399 if (!(capabilities & BDI_CAP_MAP_COPY)) 1400 goto error_just_free; 1401 1402 capabilities &= ~BDI_CAP_MAP_DIRECT; 1403 } else { 1404 vma->vm_start = region->vm_start = addr; 1405 vma->vm_end = region->vm_end = addr + len; 1406 } 1407 } 1408 } 1409 1410 vma->vm_region = region; 1411 1412 /* set up the mapping 1413 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set 1414 */ 1415 if (file && vma->vm_flags & VM_SHARED) 1416 ret = do_mmap_shared_file(vma); 1417 else 1418 ret = do_mmap_private(vma, region, len, capabilities); 1419 if (ret < 0) 1420 goto error_just_free; 1421 add_nommu_region(region); 1422 1423 /* clear anonymous mappings that don't ask for uninitialized data */ 1424 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) 1425 memset((void *)region->vm_start, 0, 1426 region->vm_end - region->vm_start); 1427 1428 /* okay... we have a mapping; now we have to register it */ 1429 result = vma->vm_start; 1430 1431 current->mm->total_vm += len >> PAGE_SHIFT; 1432 1433 share: 1434 add_vma_to_mm(current->mm, vma); 1435 1436 /* we flush the region from the icache only when the first executable 1437 * mapping of it is made */ 1438 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { 1439 flush_icache_range(region->vm_start, region->vm_end); 1440 region->vm_icache_flushed = true; 1441 } 1442 1443 up_write(&nommu_region_sem); 1444 1445 kleave(" = %lx", result); 1446 return result; 1447 1448 error_just_free: 1449 up_write(&nommu_region_sem); 1450 error: 1451 if (region->vm_file) 1452 fput(region->vm_file); 1453 kmem_cache_free(vm_region_jar, region); 1454 if (vma->vm_file) 1455 fput(vma->vm_file); 1456 kmem_cache_free(vm_area_cachep, vma); 1457 kleave(" = %d", ret); 1458 return ret; 1459 1460 sharing_violation: 1461 up_write(&nommu_region_sem); 1462 printk(KERN_WARNING "Attempt to share mismatched mappings\n"); 1463 ret = -EINVAL; 1464 goto error; 1465 1466 error_getting_vma: 1467 kmem_cache_free(vm_region_jar, region); 1468 printk(KERN_WARNING "Allocation of vma for %lu byte allocation" 1469 " from process %d failed\n", 1470 len, current->pid); 1471 show_free_areas(0); 1472 return -ENOMEM; 1473 1474 error_getting_region: 1475 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation" 1476 " from process %d failed\n", 1477 len, current->pid); 1478 show_free_areas(0); 1479 return -ENOMEM; 1480 } 1481 1482 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1483 unsigned long, prot, unsigned long, flags, 1484 unsigned long, fd, unsigned long, pgoff) 1485 { 1486 struct file *file = NULL; 1487 unsigned long retval = -EBADF; 1488 1489 audit_mmap_fd(fd, flags); 1490 if (!(flags & MAP_ANONYMOUS)) { 1491 file = fget(fd); 1492 if (!file) 1493 goto out; 1494 } 1495 1496 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1497 1498 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1499 1500 if (file) 1501 fput(file); 1502 out: 1503 return retval; 1504 } 1505 1506 #ifdef __ARCH_WANT_SYS_OLD_MMAP 1507 struct mmap_arg_struct { 1508 unsigned long addr; 1509 unsigned long len; 1510 unsigned long prot; 1511 unsigned long flags; 1512 unsigned long fd; 1513 unsigned long offset; 1514 }; 1515 1516 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1517 { 1518 struct mmap_arg_struct a; 1519 1520 if (copy_from_user(&a, arg, sizeof(a))) 1521 return -EFAULT; 1522 if (a.offset & ~PAGE_MASK) 1523 return -EINVAL; 1524 1525 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1526 a.offset >> PAGE_SHIFT); 1527 } 1528 #endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1529 1530 /* 1531 * split a vma into two pieces at address 'addr', a new vma is allocated either 1532 * for the first part or the tail. 1533 */ 1534 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 1535 unsigned long addr, int new_below) 1536 { 1537 struct vm_area_struct *new; 1538 struct vm_region *region; 1539 unsigned long npages; 1540 1541 kenter(""); 1542 1543 /* we're only permitted to split anonymous regions (these should have 1544 * only a single usage on the region) */ 1545 if (vma->vm_file) 1546 return -ENOMEM; 1547 1548 if (mm->map_count >= sysctl_max_map_count) 1549 return -ENOMEM; 1550 1551 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); 1552 if (!region) 1553 return -ENOMEM; 1554 1555 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1556 if (!new) { 1557 kmem_cache_free(vm_region_jar, region); 1558 return -ENOMEM; 1559 } 1560 1561 /* most fields are the same, copy all, and then fixup */ 1562 *new = *vma; 1563 *region = *vma->vm_region; 1564 new->vm_region = region; 1565 1566 npages = (addr - vma->vm_start) >> PAGE_SHIFT; 1567 1568 if (new_below) { 1569 region->vm_top = region->vm_end = new->vm_end = addr; 1570 } else { 1571 region->vm_start = new->vm_start = addr; 1572 region->vm_pgoff = new->vm_pgoff += npages; 1573 } 1574 1575 if (new->vm_ops && new->vm_ops->open) 1576 new->vm_ops->open(new); 1577 1578 delete_vma_from_mm(vma); 1579 down_write(&nommu_region_sem); 1580 delete_nommu_region(vma->vm_region); 1581 if (new_below) { 1582 vma->vm_region->vm_start = vma->vm_start = addr; 1583 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; 1584 } else { 1585 vma->vm_region->vm_end = vma->vm_end = addr; 1586 vma->vm_region->vm_top = addr; 1587 } 1588 add_nommu_region(vma->vm_region); 1589 add_nommu_region(new->vm_region); 1590 up_write(&nommu_region_sem); 1591 add_vma_to_mm(mm, vma); 1592 add_vma_to_mm(mm, new); 1593 return 0; 1594 } 1595 1596 /* 1597 * shrink a VMA by removing the specified chunk from either the beginning or 1598 * the end 1599 */ 1600 static int shrink_vma(struct mm_struct *mm, 1601 struct vm_area_struct *vma, 1602 unsigned long from, unsigned long to) 1603 { 1604 struct vm_region *region; 1605 1606 kenter(""); 1607 1608 /* adjust the VMA's pointers, which may reposition it in the MM's tree 1609 * and list */ 1610 delete_vma_from_mm(vma); 1611 if (from > vma->vm_start) 1612 vma->vm_end = from; 1613 else 1614 vma->vm_start = to; 1615 add_vma_to_mm(mm, vma); 1616 1617 /* cut the backing region down to size */ 1618 region = vma->vm_region; 1619 BUG_ON(region->vm_usage != 1); 1620 1621 down_write(&nommu_region_sem); 1622 delete_nommu_region(region); 1623 if (from > region->vm_start) { 1624 to = region->vm_top; 1625 region->vm_top = region->vm_end = from; 1626 } else { 1627 region->vm_start = to; 1628 } 1629 add_nommu_region(region); 1630 up_write(&nommu_region_sem); 1631 1632 free_page_series(from, to); 1633 return 0; 1634 } 1635 1636 /* 1637 * release a mapping 1638 * - under NOMMU conditions the chunk to be unmapped must be backed by a single 1639 * VMA, though it need not cover the whole VMA 1640 */ 1641 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1642 { 1643 struct vm_area_struct *vma; 1644 unsigned long end; 1645 int ret; 1646 1647 kenter(",%lx,%zx", start, len); 1648 1649 len = PAGE_ALIGN(len); 1650 if (len == 0) 1651 return -EINVAL; 1652 1653 end = start + len; 1654 1655 /* find the first potentially overlapping VMA */ 1656 vma = find_vma(mm, start); 1657 if (!vma) { 1658 static int limit = 0; 1659 if (limit < 5) { 1660 printk(KERN_WARNING 1661 "munmap of memory not mmapped by process %d" 1662 " (%s): 0x%lx-0x%lx\n", 1663 current->pid, current->comm, 1664 start, start + len - 1); 1665 limit++; 1666 } 1667 return -EINVAL; 1668 } 1669 1670 /* we're allowed to split an anonymous VMA but not a file-backed one */ 1671 if (vma->vm_file) { 1672 do { 1673 if (start > vma->vm_start) { 1674 kleave(" = -EINVAL [miss]"); 1675 return -EINVAL; 1676 } 1677 if (end == vma->vm_end) 1678 goto erase_whole_vma; 1679 vma = vma->vm_next; 1680 } while (vma); 1681 kleave(" = -EINVAL [split file]"); 1682 return -EINVAL; 1683 } else { 1684 /* the chunk must be a subset of the VMA found */ 1685 if (start == vma->vm_start && end == vma->vm_end) 1686 goto erase_whole_vma; 1687 if (start < vma->vm_start || end > vma->vm_end) { 1688 kleave(" = -EINVAL [superset]"); 1689 return -EINVAL; 1690 } 1691 if (start & ~PAGE_MASK) { 1692 kleave(" = -EINVAL [unaligned start]"); 1693 return -EINVAL; 1694 } 1695 if (end != vma->vm_end && end & ~PAGE_MASK) { 1696 kleave(" = -EINVAL [unaligned split]"); 1697 return -EINVAL; 1698 } 1699 if (start != vma->vm_start && end != vma->vm_end) { 1700 ret = split_vma(mm, vma, start, 1); 1701 if (ret < 0) { 1702 kleave(" = %d [split]", ret); 1703 return ret; 1704 } 1705 } 1706 return shrink_vma(mm, vma, start, end); 1707 } 1708 1709 erase_whole_vma: 1710 delete_vma_from_mm(vma); 1711 delete_vma(mm, vma); 1712 kleave(" = 0"); 1713 return 0; 1714 } 1715 EXPORT_SYMBOL(do_munmap); 1716 1717 int vm_munmap(unsigned long addr, size_t len) 1718 { 1719 struct mm_struct *mm = current->mm; 1720 int ret; 1721 1722 down_write(&mm->mmap_sem); 1723 ret = do_munmap(mm, addr, len); 1724 up_write(&mm->mmap_sem); 1725 return ret; 1726 } 1727 EXPORT_SYMBOL(vm_munmap); 1728 1729 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1730 { 1731 return vm_munmap(addr, len); 1732 } 1733 1734 /* 1735 * release all the mappings made in a process's VM space 1736 */ 1737 void exit_mmap(struct mm_struct *mm) 1738 { 1739 struct vm_area_struct *vma; 1740 1741 if (!mm) 1742 return; 1743 1744 kenter(""); 1745 1746 mm->total_vm = 0; 1747 1748 while ((vma = mm->mmap)) { 1749 mm->mmap = vma->vm_next; 1750 delete_vma_from_mm(vma); 1751 delete_vma(mm, vma); 1752 cond_resched(); 1753 } 1754 1755 kleave(""); 1756 } 1757 1758 unsigned long vm_brk(unsigned long addr, unsigned long len) 1759 { 1760 return -ENOMEM; 1761 } 1762 1763 /* 1764 * expand (or shrink) an existing mapping, potentially moving it at the same 1765 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1766 * 1767 * under NOMMU conditions, we only permit changing a mapping's size, and only 1768 * as long as it stays within the region allocated by do_mmap_private() and the 1769 * block is not shareable 1770 * 1771 * MREMAP_FIXED is not supported under NOMMU conditions 1772 */ 1773 unsigned long do_mremap(unsigned long addr, 1774 unsigned long old_len, unsigned long new_len, 1775 unsigned long flags, unsigned long new_addr) 1776 { 1777 struct vm_area_struct *vma; 1778 1779 /* insanity checks first */ 1780 old_len = PAGE_ALIGN(old_len); 1781 new_len = PAGE_ALIGN(new_len); 1782 if (old_len == 0 || new_len == 0) 1783 return (unsigned long) -EINVAL; 1784 1785 if (addr & ~PAGE_MASK) 1786 return -EINVAL; 1787 1788 if (flags & MREMAP_FIXED && new_addr != addr) 1789 return (unsigned long) -EINVAL; 1790 1791 vma = find_vma_exact(current->mm, addr, old_len); 1792 if (!vma) 1793 return (unsigned long) -EINVAL; 1794 1795 if (vma->vm_end != vma->vm_start + old_len) 1796 return (unsigned long) -EFAULT; 1797 1798 if (vma->vm_flags & VM_MAYSHARE) 1799 return (unsigned long) -EPERM; 1800 1801 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) 1802 return (unsigned long) -ENOMEM; 1803 1804 /* all checks complete - do it */ 1805 vma->vm_end = vma->vm_start + new_len; 1806 return vma->vm_start; 1807 } 1808 EXPORT_SYMBOL(do_mremap); 1809 1810 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, 1811 unsigned long, new_len, unsigned long, flags, 1812 unsigned long, new_addr) 1813 { 1814 unsigned long ret; 1815 1816 down_write(¤t->mm->mmap_sem); 1817 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1818 up_write(¤t->mm->mmap_sem); 1819 return ret; 1820 } 1821 1822 struct page *follow_page_mask(struct vm_area_struct *vma, 1823 unsigned long address, unsigned int flags, 1824 unsigned int *page_mask) 1825 { 1826 *page_mask = 0; 1827 return NULL; 1828 } 1829 1830 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 1831 unsigned long pfn, unsigned long size, pgprot_t prot) 1832 { 1833 if (addr != (pfn << PAGE_SHIFT)) 1834 return -EINVAL; 1835 1836 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP; 1837 return 0; 1838 } 1839 EXPORT_SYMBOL(remap_pfn_range); 1840 1841 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 1842 unsigned long pgoff) 1843 { 1844 unsigned int size = vma->vm_end - vma->vm_start; 1845 1846 if (!(vma->vm_flags & VM_USERMAP)) 1847 return -EINVAL; 1848 1849 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); 1850 vma->vm_end = vma->vm_start + size; 1851 1852 return 0; 1853 } 1854 EXPORT_SYMBOL(remap_vmalloc_range); 1855 1856 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1857 unsigned long len, unsigned long pgoff, unsigned long flags) 1858 { 1859 return -ENOMEM; 1860 } 1861 1862 void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1863 { 1864 } 1865 1866 void unmap_mapping_range(struct address_space *mapping, 1867 loff_t const holebegin, loff_t const holelen, 1868 int even_cows) 1869 { 1870 } 1871 EXPORT_SYMBOL(unmap_mapping_range); 1872 1873 /* 1874 * Check that a process has enough memory to allocate a new virtual 1875 * mapping. 0 means there is enough memory for the allocation to 1876 * succeed and -ENOMEM implies there is not. 1877 * 1878 * We currently support three overcommit policies, which are set via the 1879 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1880 * 1881 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1882 * Additional code 2002 Jul 20 by Robert Love. 1883 * 1884 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1885 * 1886 * Note this is a helper function intended to be used by LSMs which 1887 * wish to use this logic. 1888 */ 1889 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 1890 { 1891 unsigned long free, allowed; 1892 1893 vm_acct_memory(pages); 1894 1895 /* 1896 * Sometimes we want to use more memory than we have 1897 */ 1898 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1899 return 0; 1900 1901 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1902 free = global_page_state(NR_FREE_PAGES); 1903 free += global_page_state(NR_FILE_PAGES); 1904 1905 /* 1906 * shmem pages shouldn't be counted as free in this 1907 * case, they can't be purged, only swapped out, and 1908 * that won't affect the overall amount of available 1909 * memory in the system. 1910 */ 1911 free -= global_page_state(NR_SHMEM); 1912 1913 free += get_nr_swap_pages(); 1914 1915 /* 1916 * Any slabs which are created with the 1917 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1918 * which are reclaimable, under pressure. The dentry 1919 * cache and most inode caches should fall into this 1920 */ 1921 free += global_page_state(NR_SLAB_RECLAIMABLE); 1922 1923 /* 1924 * Leave reserved pages. The pages are not for anonymous pages. 1925 */ 1926 if (free <= totalreserve_pages) 1927 goto error; 1928 else 1929 free -= totalreserve_pages; 1930 1931 /* 1932 * Leave the last 3% for root 1933 */ 1934 if (!cap_sys_admin) 1935 free -= free / 32; 1936 1937 if (free > pages) 1938 return 0; 1939 1940 goto error; 1941 } 1942 1943 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1944 /* 1945 * Leave the last 3% for root 1946 */ 1947 if (!cap_sys_admin) 1948 allowed -= allowed / 32; 1949 allowed += total_swap_pages; 1950 1951 /* Don't let a single process grow too big: 1952 leave 3% of the size of this process for other processes */ 1953 if (mm) 1954 allowed -= mm->total_vm / 32; 1955 1956 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 1957 return 0; 1958 1959 error: 1960 vm_unacct_memory(pages); 1961 1962 return -ENOMEM; 1963 } 1964 1965 int in_gate_area_no_mm(unsigned long addr) 1966 { 1967 return 0; 1968 } 1969 1970 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1971 { 1972 BUG(); 1973 return 0; 1974 } 1975 EXPORT_SYMBOL(filemap_fault); 1976 1977 int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr, 1978 unsigned long size, pgoff_t pgoff) 1979 { 1980 BUG(); 1981 return 0; 1982 } 1983 EXPORT_SYMBOL(generic_file_remap_pages); 1984 1985 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 1986 unsigned long addr, void *buf, int len, int write) 1987 { 1988 struct vm_area_struct *vma; 1989 1990 down_read(&mm->mmap_sem); 1991 1992 /* the access must start within one of the target process's mappings */ 1993 vma = find_vma(mm, addr); 1994 if (vma) { 1995 /* don't overrun this mapping */ 1996 if (addr + len >= vma->vm_end) 1997 len = vma->vm_end - addr; 1998 1999 /* only read or write mappings where it is permitted */ 2000 if (write && vma->vm_flags & VM_MAYWRITE) 2001 copy_to_user_page(vma, NULL, addr, 2002 (void *) addr, buf, len); 2003 else if (!write && vma->vm_flags & VM_MAYREAD) 2004 copy_from_user_page(vma, NULL, addr, 2005 buf, (void *) addr, len); 2006 else 2007 len = 0; 2008 } else { 2009 len = 0; 2010 } 2011 2012 up_read(&mm->mmap_sem); 2013 2014 return len; 2015 } 2016 2017 /** 2018 * @access_remote_vm - access another process' address space 2019 * @mm: the mm_struct of the target address space 2020 * @addr: start address to access 2021 * @buf: source or destination buffer 2022 * @len: number of bytes to transfer 2023 * @write: whether the access is a write 2024 * 2025 * The caller must hold a reference on @mm. 2026 */ 2027 int access_remote_vm(struct mm_struct *mm, unsigned long addr, 2028 void *buf, int len, int write) 2029 { 2030 return __access_remote_vm(NULL, mm, addr, buf, len, write); 2031 } 2032 2033 /* 2034 * Access another process' address space. 2035 * - source/target buffer must be kernel space 2036 */ 2037 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2038 { 2039 struct mm_struct *mm; 2040 2041 if (addr + len < addr) 2042 return 0; 2043 2044 mm = get_task_mm(tsk); 2045 if (!mm) 2046 return 0; 2047 2048 len = __access_remote_vm(tsk, mm, addr, buf, len, write); 2049 2050 mmput(mm); 2051 return len; 2052 } 2053 2054 /** 2055 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode 2056 * @inode: The inode to check 2057 * @size: The current filesize of the inode 2058 * @newsize: The proposed filesize of the inode 2059 * 2060 * Check the shared mappings on an inode on behalf of a shrinking truncate to 2061 * make sure that that any outstanding VMAs aren't broken and then shrink the 2062 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't 2063 * automatically grant mappings that are too large. 2064 */ 2065 int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 2066 size_t newsize) 2067 { 2068 struct vm_area_struct *vma; 2069 struct vm_region *region; 2070 pgoff_t low, high; 2071 size_t r_size, r_top; 2072 2073 low = newsize >> PAGE_SHIFT; 2074 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 2075 2076 down_write(&nommu_region_sem); 2077 mutex_lock(&inode->i_mapping->i_mmap_mutex); 2078 2079 /* search for VMAs that fall within the dead zone */ 2080 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { 2081 /* found one - only interested if it's shared out of the page 2082 * cache */ 2083 if (vma->vm_flags & VM_SHARED) { 2084 mutex_unlock(&inode->i_mapping->i_mmap_mutex); 2085 up_write(&nommu_region_sem); 2086 return -ETXTBSY; /* not quite true, but near enough */ 2087 } 2088 } 2089 2090 /* reduce any regions that overlap the dead zone - if in existence, 2091 * these will be pointed to by VMAs that don't overlap the dead zone 2092 * 2093 * we don't check for any regions that start beyond the EOF as there 2094 * shouldn't be any 2095 */ 2096 vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 2097 0, ULONG_MAX) { 2098 if (!(vma->vm_flags & VM_SHARED)) 2099 continue; 2100 2101 region = vma->vm_region; 2102 r_size = region->vm_top - region->vm_start; 2103 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; 2104 2105 if (r_top > newsize) { 2106 region->vm_top -= r_top - newsize; 2107 if (region->vm_end > region->vm_top) 2108 region->vm_end = region->vm_top; 2109 } 2110 } 2111 2112 mutex_unlock(&inode->i_mapping->i_mmap_mutex); 2113 up_write(&nommu_region_sem); 2114 return 0; 2115 } 2116