nommu.c revision e922c4c5360980bfeb862b3ec307d36bb344dcae
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/module.h> 17#include <linux/mm.h> 18#include <linux/mman.h> 19#include <linux/swap.h> 20#include <linux/file.h> 21#include <linux/highmem.h> 22#include <linux/pagemap.h> 23#include <linux/slab.h> 24#include <linux/vmalloc.h> 25#include <linux/tracehook.h> 26#include <linux/blkdev.h> 27#include <linux/backing-dev.h> 28#include <linux/mount.h> 29#include <linux/personality.h> 30#include <linux/security.h> 31#include <linux/syscalls.h> 32#include <linux/audit.h> 33 34#include <asm/uaccess.h> 35#include <asm/tlb.h> 36#include <asm/tlbflush.h> 37#include <asm/mmu_context.h> 38#include "internal.h" 39 40#if 0 41#define kenter(FMT, ...) \ 42 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 43#define kleave(FMT, ...) \ 44 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 45#define kdebug(FMT, ...) \ 46 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__) 47#else 48#define kenter(FMT, ...) \ 49 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 50#define kleave(FMT, ...) \ 51 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 52#define kdebug(FMT, ...) \ 53 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__) 54#endif 55 56void *high_memory; 57struct page *mem_map; 58unsigned long max_mapnr; 59unsigned long num_physpages; 60unsigned long highest_memmap_pfn; 61struct percpu_counter vm_committed_as; 62int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 63int sysctl_overcommit_ratio = 50; /* default is 50% */ 64int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 65int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; 66int heap_stack_gap = 0; 67 68atomic_long_t mmap_pages_allocated; 69 70EXPORT_SYMBOL(mem_map); 71EXPORT_SYMBOL(num_physpages); 72 73/* list of mapped, potentially shareable regions */ 74static struct kmem_cache *vm_region_jar; 75struct rb_root nommu_region_tree = RB_ROOT; 76DECLARE_RWSEM(nommu_region_sem); 77 78const struct vm_operations_struct generic_file_vm_ops = { 79}; 80 81/* 82 * Return the total memory allocated for this pointer, not 83 * just what the caller asked for. 84 * 85 * Doesn't have to be accurate, i.e. may have races. 86 */ 87unsigned int kobjsize(const void *objp) 88{ 89 struct page *page; 90 91 /* 92 * If the object we have should not have ksize performed on it, 93 * return size of 0 94 */ 95 if (!objp || !virt_addr_valid(objp)) 96 return 0; 97 98 page = virt_to_head_page(objp); 99 100 /* 101 * If the allocator sets PageSlab, we know the pointer came from 102 * kmalloc(). 103 */ 104 if (PageSlab(page)) 105 return ksize(objp); 106 107 /* 108 * If it's not a compound page, see if we have a matching VMA 109 * region. This test is intentionally done in reverse order, 110 * so if there's no VMA, we still fall through and hand back 111 * PAGE_SIZE for 0-order pages. 112 */ 113 if (!PageCompound(page)) { 114 struct vm_area_struct *vma; 115 116 vma = find_vma(current->mm, (unsigned long)objp); 117 if (vma) 118 return vma->vm_end - vma->vm_start; 119 } 120 121 /* 122 * The ksize() function is only guaranteed to work for pointers 123 * returned by kmalloc(). So handle arbitrary pointers here. 124 */ 125 return PAGE_SIZE << compound_order(page); 126} 127 128int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 129 unsigned long start, int nr_pages, unsigned int foll_flags, 130 struct page **pages, struct vm_area_struct **vmas, 131 int *retry) 132{ 133 struct vm_area_struct *vma; 134 unsigned long vm_flags; 135 int i; 136 137 /* calculate required read or write permissions. 138 * If FOLL_FORCE is set, we only require the "MAY" flags. 139 */ 140 vm_flags = (foll_flags & FOLL_WRITE) ? 141 (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 142 vm_flags &= (foll_flags & FOLL_FORCE) ? 143 (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 144 145 for (i = 0; i < nr_pages; i++) { 146 vma = find_vma(mm, start); 147 if (!vma) 148 goto finish_or_fault; 149 150 /* protect what we can, including chardevs */ 151 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || 152 !(vm_flags & vma->vm_flags)) 153 goto finish_or_fault; 154 155 if (pages) { 156 pages[i] = virt_to_page(start); 157 if (pages[i]) 158 page_cache_get(pages[i]); 159 } 160 if (vmas) 161 vmas[i] = vma; 162 start = (start + PAGE_SIZE) & PAGE_MASK; 163 } 164 165 return i; 166 167finish_or_fault: 168 return i ? : -EFAULT; 169} 170 171/* 172 * get a list of pages in an address range belonging to the specified process 173 * and indicate the VMA that covers each page 174 * - this is potentially dodgy as we may end incrementing the page count of a 175 * slab page or a secondary page from a compound page 176 * - don't permit access to VMAs that don't support it, such as I/O mappings 177 */ 178int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 179 unsigned long start, int nr_pages, int write, int force, 180 struct page **pages, struct vm_area_struct **vmas) 181{ 182 int flags = 0; 183 184 if (write) 185 flags |= FOLL_WRITE; 186 if (force) 187 flags |= FOLL_FORCE; 188 189 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas, 190 NULL); 191} 192EXPORT_SYMBOL(get_user_pages); 193 194/** 195 * follow_pfn - look up PFN at a user virtual address 196 * @vma: memory mapping 197 * @address: user virtual address 198 * @pfn: location to store found PFN 199 * 200 * Only IO mappings and raw PFN mappings are allowed. 201 * 202 * Returns zero and the pfn at @pfn on success, -ve otherwise. 203 */ 204int follow_pfn(struct vm_area_struct *vma, unsigned long address, 205 unsigned long *pfn) 206{ 207 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 208 return -EINVAL; 209 210 *pfn = address >> PAGE_SHIFT; 211 return 0; 212} 213EXPORT_SYMBOL(follow_pfn); 214 215DEFINE_RWLOCK(vmlist_lock); 216struct vm_struct *vmlist; 217 218void vfree(const void *addr) 219{ 220 kfree(addr); 221} 222EXPORT_SYMBOL(vfree); 223 224void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 225{ 226 /* 227 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() 228 * returns only a logical address. 229 */ 230 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 231} 232EXPORT_SYMBOL(__vmalloc); 233 234void *vmalloc_user(unsigned long size) 235{ 236 void *ret; 237 238 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 239 PAGE_KERNEL); 240 if (ret) { 241 struct vm_area_struct *vma; 242 243 down_write(¤t->mm->mmap_sem); 244 vma = find_vma(current->mm, (unsigned long)ret); 245 if (vma) 246 vma->vm_flags |= VM_USERMAP; 247 up_write(¤t->mm->mmap_sem); 248 } 249 250 return ret; 251} 252EXPORT_SYMBOL(vmalloc_user); 253 254struct page *vmalloc_to_page(const void *addr) 255{ 256 return virt_to_page(addr); 257} 258EXPORT_SYMBOL(vmalloc_to_page); 259 260unsigned long vmalloc_to_pfn(const void *addr) 261{ 262 return page_to_pfn(virt_to_page(addr)); 263} 264EXPORT_SYMBOL(vmalloc_to_pfn); 265 266long vread(char *buf, char *addr, unsigned long count) 267{ 268 memcpy(buf, addr, count); 269 return count; 270} 271 272long vwrite(char *buf, char *addr, unsigned long count) 273{ 274 /* Don't allow overflow */ 275 if ((unsigned long) addr + count < count) 276 count = -(unsigned long) addr; 277 278 memcpy(addr, buf, count); 279 return(count); 280} 281 282/* 283 * vmalloc - allocate virtually continguos memory 284 * 285 * @size: allocation size 286 * 287 * Allocate enough pages to cover @size from the page level 288 * allocator and map them into continguos kernel virtual space. 289 * 290 * For tight control over page level allocator and protection flags 291 * use __vmalloc() instead. 292 */ 293void *vmalloc(unsigned long size) 294{ 295 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 296} 297EXPORT_SYMBOL(vmalloc); 298 299/* 300 * vzalloc - allocate virtually continguos memory with zero fill 301 * 302 * @size: allocation size 303 * 304 * Allocate enough pages to cover @size from the page level 305 * allocator and map them into continguos kernel virtual space. 306 * The memory allocated is set to zero. 307 * 308 * For tight control over page level allocator and protection flags 309 * use __vmalloc() instead. 310 */ 311void *vzalloc(unsigned long size) 312{ 313 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 314 PAGE_KERNEL); 315} 316EXPORT_SYMBOL(vzalloc); 317 318/** 319 * vmalloc_node - allocate memory on a specific node 320 * @size: allocation size 321 * @node: numa node 322 * 323 * Allocate enough pages to cover @size from the page level 324 * allocator and map them into contiguous kernel virtual space. 325 * 326 * For tight control over page level allocator and protection flags 327 * use __vmalloc() instead. 328 */ 329void *vmalloc_node(unsigned long size, int node) 330{ 331 return vmalloc(size); 332} 333EXPORT_SYMBOL(vmalloc_node); 334 335/** 336 * vzalloc_node - allocate memory on a specific node with zero fill 337 * @size: allocation size 338 * @node: numa node 339 * 340 * Allocate enough pages to cover @size from the page level 341 * allocator and map them into contiguous kernel virtual space. 342 * The memory allocated is set to zero. 343 * 344 * For tight control over page level allocator and protection flags 345 * use __vmalloc() instead. 346 */ 347void *vzalloc_node(unsigned long size, int node) 348{ 349 return vzalloc(size); 350} 351EXPORT_SYMBOL(vzalloc_node); 352 353#ifndef PAGE_KERNEL_EXEC 354# define PAGE_KERNEL_EXEC PAGE_KERNEL 355#endif 356 357/** 358 * vmalloc_exec - allocate virtually contiguous, executable memory 359 * @size: allocation size 360 * 361 * Kernel-internal function to allocate enough pages to cover @size 362 * the page level allocator and map them into contiguous and 363 * executable kernel virtual space. 364 * 365 * For tight control over page level allocator and protection flags 366 * use __vmalloc() instead. 367 */ 368 369void *vmalloc_exec(unsigned long size) 370{ 371 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); 372} 373 374/** 375 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) 376 * @size: allocation size 377 * 378 * Allocate enough 32bit PA addressable pages to cover @size from the 379 * page level allocator and map them into continguos kernel virtual space. 380 */ 381void *vmalloc_32(unsigned long size) 382{ 383 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 384} 385EXPORT_SYMBOL(vmalloc_32); 386 387/** 388 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory 389 * @size: allocation size 390 * 391 * The resulting memory area is 32bit addressable and zeroed so it can be 392 * mapped to userspace without leaking data. 393 * 394 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to 395 * remap_vmalloc_range() are permissible. 396 */ 397void *vmalloc_32_user(unsigned long size) 398{ 399 /* 400 * We'll have to sort out the ZONE_DMA bits for 64-bit, 401 * but for now this can simply use vmalloc_user() directly. 402 */ 403 return vmalloc_user(size); 404} 405EXPORT_SYMBOL(vmalloc_32_user); 406 407void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 408{ 409 BUG(); 410 return NULL; 411} 412EXPORT_SYMBOL(vmap); 413 414void vunmap(const void *addr) 415{ 416 BUG(); 417} 418EXPORT_SYMBOL(vunmap); 419 420void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) 421{ 422 BUG(); 423 return NULL; 424} 425EXPORT_SYMBOL(vm_map_ram); 426 427void vm_unmap_ram(const void *mem, unsigned int count) 428{ 429 BUG(); 430} 431EXPORT_SYMBOL(vm_unmap_ram); 432 433void vm_unmap_aliases(void) 434{ 435} 436EXPORT_SYMBOL_GPL(vm_unmap_aliases); 437 438/* 439 * Implement a stub for vmalloc_sync_all() if the architecture chose not to 440 * have one. 441 */ 442void __attribute__((weak)) vmalloc_sync_all(void) 443{ 444} 445 446/** 447 * alloc_vm_area - allocate a range of kernel address space 448 * @size: size of the area 449 * 450 * Returns: NULL on failure, vm_struct on success 451 * 452 * This function reserves a range of kernel address space, and 453 * allocates pagetables to map that range. No actual mappings 454 * are created. If the kernel address space is not shared 455 * between processes, it syncs the pagetable across all 456 * processes. 457 */ 458struct vm_struct *alloc_vm_area(size_t size) 459{ 460 BUG(); 461 return NULL; 462} 463EXPORT_SYMBOL_GPL(alloc_vm_area); 464 465void free_vm_area(struct vm_struct *area) 466{ 467 BUG(); 468} 469EXPORT_SYMBOL_GPL(free_vm_area); 470 471int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 472 struct page *page) 473{ 474 return -EINVAL; 475} 476EXPORT_SYMBOL(vm_insert_page); 477 478/* 479 * sys_brk() for the most part doesn't need the global kernel 480 * lock, except when an application is doing something nasty 481 * like trying to un-brk an area that has already been mapped 482 * to a regular file. in this case, the unmapping will need 483 * to invoke file system routines that need the global lock. 484 */ 485SYSCALL_DEFINE1(brk, unsigned long, brk) 486{ 487 struct mm_struct *mm = current->mm; 488 489 if (brk < mm->start_brk || brk > mm->context.end_brk) 490 return mm->brk; 491 492 if (mm->brk == brk) 493 return mm->brk; 494 495 /* 496 * Always allow shrinking brk 497 */ 498 if (brk <= mm->brk) { 499 mm->brk = brk; 500 return brk; 501 } 502 503 /* 504 * Ok, looks good - let it rip. 505 */ 506 flush_icache_range(mm->brk, brk); 507 return mm->brk = brk; 508} 509 510/* 511 * initialise the VMA and region record slabs 512 */ 513void __init mmap_init(void) 514{ 515 int ret; 516 517 ret = percpu_counter_init(&vm_committed_as, 0); 518 VM_BUG_ON(ret); 519 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC); 520} 521 522/* 523 * validate the region tree 524 * - the caller must hold the region lock 525 */ 526#ifdef CONFIG_DEBUG_NOMMU_REGIONS 527static noinline void validate_nommu_regions(void) 528{ 529 struct vm_region *region, *last; 530 struct rb_node *p, *lastp; 531 532 lastp = rb_first(&nommu_region_tree); 533 if (!lastp) 534 return; 535 536 last = rb_entry(lastp, struct vm_region, vm_rb); 537 BUG_ON(unlikely(last->vm_end <= last->vm_start)); 538 BUG_ON(unlikely(last->vm_top < last->vm_end)); 539 540 while ((p = rb_next(lastp))) { 541 region = rb_entry(p, struct vm_region, vm_rb); 542 last = rb_entry(lastp, struct vm_region, vm_rb); 543 544 BUG_ON(unlikely(region->vm_end <= region->vm_start)); 545 BUG_ON(unlikely(region->vm_top < region->vm_end)); 546 BUG_ON(unlikely(region->vm_start < last->vm_top)); 547 548 lastp = p; 549 } 550} 551#else 552static void validate_nommu_regions(void) 553{ 554} 555#endif 556 557/* 558 * add a region into the global tree 559 */ 560static void add_nommu_region(struct vm_region *region) 561{ 562 struct vm_region *pregion; 563 struct rb_node **p, *parent; 564 565 validate_nommu_regions(); 566 567 parent = NULL; 568 p = &nommu_region_tree.rb_node; 569 while (*p) { 570 parent = *p; 571 pregion = rb_entry(parent, struct vm_region, vm_rb); 572 if (region->vm_start < pregion->vm_start) 573 p = &(*p)->rb_left; 574 else if (region->vm_start > pregion->vm_start) 575 p = &(*p)->rb_right; 576 else if (pregion == region) 577 return; 578 else 579 BUG(); 580 } 581 582 rb_link_node(®ion->vm_rb, parent, p); 583 rb_insert_color(®ion->vm_rb, &nommu_region_tree); 584 585 validate_nommu_regions(); 586} 587 588/* 589 * delete a region from the global tree 590 */ 591static void delete_nommu_region(struct vm_region *region) 592{ 593 BUG_ON(!nommu_region_tree.rb_node); 594 595 validate_nommu_regions(); 596 rb_erase(®ion->vm_rb, &nommu_region_tree); 597 validate_nommu_regions(); 598} 599 600/* 601 * free a contiguous series of pages 602 */ 603static void free_page_series(unsigned long from, unsigned long to) 604{ 605 for (; from < to; from += PAGE_SIZE) { 606 struct page *page = virt_to_page(from); 607 608 kdebug("- free %lx", from); 609 atomic_long_dec(&mmap_pages_allocated); 610 if (page_count(page) != 1) 611 kdebug("free page %p: refcount not one: %d", 612 page, page_count(page)); 613 put_page(page); 614 } 615} 616 617/* 618 * release a reference to a region 619 * - the caller must hold the region semaphore for writing, which this releases 620 * - the region may not have been added to the tree yet, in which case vm_top 621 * will equal vm_start 622 */ 623static void __put_nommu_region(struct vm_region *region) 624 __releases(nommu_region_sem) 625{ 626 kenter("%p{%d}", region, region->vm_usage); 627 628 BUG_ON(!nommu_region_tree.rb_node); 629 630 if (--region->vm_usage == 0) { 631 if (region->vm_top > region->vm_start) 632 delete_nommu_region(region); 633 up_write(&nommu_region_sem); 634 635 if (region->vm_file) 636 fput(region->vm_file); 637 638 /* IO memory and memory shared directly out of the pagecache 639 * from ramfs/tmpfs mustn't be released here */ 640 if (region->vm_flags & VM_MAPPED_COPY) { 641 kdebug("free series"); 642 free_page_series(region->vm_start, region->vm_top); 643 } 644 kmem_cache_free(vm_region_jar, region); 645 } else { 646 up_write(&nommu_region_sem); 647 } 648} 649 650/* 651 * release a reference to a region 652 */ 653static void put_nommu_region(struct vm_region *region) 654{ 655 down_write(&nommu_region_sem); 656 __put_nommu_region(region); 657} 658 659/* 660 * update protection on a vma 661 */ 662static void protect_vma(struct vm_area_struct *vma, unsigned long flags) 663{ 664#ifdef CONFIG_MPU 665 struct mm_struct *mm = vma->vm_mm; 666 long start = vma->vm_start & PAGE_MASK; 667 while (start < vma->vm_end) { 668 protect_page(mm, start, flags); 669 start += PAGE_SIZE; 670 } 671 update_protections(mm); 672#endif 673} 674 675/* 676 * add a VMA into a process's mm_struct in the appropriate place in the list 677 * and tree and add to the address space's page tree also if not an anonymous 678 * page 679 * - should be called with mm->mmap_sem held writelocked 680 */ 681static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) 682{ 683 struct vm_area_struct *pvma, *prev; 684 struct address_space *mapping; 685 struct rb_node **p, *parent, *rb_prev; 686 687 kenter(",%p", vma); 688 689 BUG_ON(!vma->vm_region); 690 691 mm->map_count++; 692 vma->vm_mm = mm; 693 694 protect_vma(vma, vma->vm_flags); 695 696 /* add the VMA to the mapping */ 697 if (vma->vm_file) { 698 mapping = vma->vm_file->f_mapping; 699 700 flush_dcache_mmap_lock(mapping); 701 vma_prio_tree_insert(vma, &mapping->i_mmap); 702 flush_dcache_mmap_unlock(mapping); 703 } 704 705 /* add the VMA to the tree */ 706 parent = rb_prev = NULL; 707 p = &mm->mm_rb.rb_node; 708 while (*p) { 709 parent = *p; 710 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 711 712 /* sort by: start addr, end addr, VMA struct addr in that order 713 * (the latter is necessary as we may get identical VMAs) */ 714 if (vma->vm_start < pvma->vm_start) 715 p = &(*p)->rb_left; 716 else if (vma->vm_start > pvma->vm_start) { 717 rb_prev = parent; 718 p = &(*p)->rb_right; 719 } else if (vma->vm_end < pvma->vm_end) 720 p = &(*p)->rb_left; 721 else if (vma->vm_end > pvma->vm_end) { 722 rb_prev = parent; 723 p = &(*p)->rb_right; 724 } else if (vma < pvma) 725 p = &(*p)->rb_left; 726 else if (vma > pvma) { 727 rb_prev = parent; 728 p = &(*p)->rb_right; 729 } else 730 BUG(); 731 } 732 733 rb_link_node(&vma->vm_rb, parent, p); 734 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 735 736 /* add VMA to the VMA list also */ 737 prev = NULL; 738 if (rb_prev) 739 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb); 740 741 __vma_link_list(mm, vma, prev, parent); 742} 743 744/* 745 * delete a VMA from its owning mm_struct and address space 746 */ 747static void delete_vma_from_mm(struct vm_area_struct *vma) 748{ 749 struct address_space *mapping; 750 struct mm_struct *mm = vma->vm_mm; 751 752 kenter("%p", vma); 753 754 protect_vma(vma, 0); 755 756 mm->map_count--; 757 if (mm->mmap_cache == vma) 758 mm->mmap_cache = NULL; 759 760 /* remove the VMA from the mapping */ 761 if (vma->vm_file) { 762 mapping = vma->vm_file->f_mapping; 763 764 flush_dcache_mmap_lock(mapping); 765 vma_prio_tree_remove(vma, &mapping->i_mmap); 766 flush_dcache_mmap_unlock(mapping); 767 } 768 769 /* remove from the MM's tree and list */ 770 rb_erase(&vma->vm_rb, &mm->mm_rb); 771 772 if (vma->vm_prev) 773 vma->vm_prev->vm_next = vma->vm_next; 774 else 775 mm->mmap = vma->vm_next; 776 777 if (vma->vm_next) 778 vma->vm_next->vm_prev = vma->vm_prev; 779 780 vma->vm_mm = NULL; 781} 782 783/* 784 * destroy a VMA record 785 */ 786static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) 787{ 788 kenter("%p", vma); 789 if (vma->vm_ops && vma->vm_ops->close) 790 vma->vm_ops->close(vma); 791 if (vma->vm_file) { 792 fput(vma->vm_file); 793 if (vma->vm_flags & VM_EXECUTABLE) 794 removed_exe_file_vma(mm); 795 } 796 put_nommu_region(vma->vm_region); 797 kmem_cache_free(vm_area_cachep, vma); 798} 799 800/* 801 * look up the first VMA in which addr resides, NULL if none 802 * - should be called with mm->mmap_sem at least held readlocked 803 */ 804struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 805{ 806 struct vm_area_struct *vma; 807 808 /* check the cache first */ 809 vma = mm->mmap_cache; 810 if (vma && vma->vm_start <= addr && vma->vm_end > addr) 811 return vma; 812 813 /* trawl the list (there may be multiple mappings in which addr 814 * resides) */ 815 for (vma = mm->mmap; vma; vma = vma->vm_next) { 816 if (vma->vm_start > addr) 817 return NULL; 818 if (vma->vm_end > addr) { 819 mm->mmap_cache = vma; 820 return vma; 821 } 822 } 823 824 return NULL; 825} 826EXPORT_SYMBOL(find_vma); 827 828/* 829 * find a VMA 830 * - we don't extend stack VMAs under NOMMU conditions 831 */ 832struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 833{ 834 return find_vma(mm, addr); 835} 836 837/* 838 * expand a stack to a given address 839 * - not supported under NOMMU conditions 840 */ 841int expand_stack(struct vm_area_struct *vma, unsigned long address) 842{ 843 return -ENOMEM; 844} 845 846/* 847 * look up the first VMA exactly that exactly matches addr 848 * - should be called with mm->mmap_sem at least held readlocked 849 */ 850static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 851 unsigned long addr, 852 unsigned long len) 853{ 854 struct vm_area_struct *vma; 855 unsigned long end = addr + len; 856 857 /* check the cache first */ 858 vma = mm->mmap_cache; 859 if (vma && vma->vm_start == addr && vma->vm_end == end) 860 return vma; 861 862 /* trawl the list (there may be multiple mappings in which addr 863 * resides) */ 864 for (vma = mm->mmap; vma; vma = vma->vm_next) { 865 if (vma->vm_start < addr) 866 continue; 867 if (vma->vm_start > addr) 868 return NULL; 869 if (vma->vm_end == end) { 870 mm->mmap_cache = vma; 871 return vma; 872 } 873 } 874 875 return NULL; 876} 877 878/* 879 * determine whether a mapping should be permitted and, if so, what sort of 880 * mapping we're capable of supporting 881 */ 882static int validate_mmap_request(struct file *file, 883 unsigned long addr, 884 unsigned long len, 885 unsigned long prot, 886 unsigned long flags, 887 unsigned long pgoff, 888 unsigned long *_capabilities) 889{ 890 unsigned long capabilities, rlen; 891 unsigned long reqprot = prot; 892 int ret; 893 894 /* do the simple checks first */ 895 if (flags & MAP_FIXED) { 896 printk(KERN_DEBUG 897 "%d: Can't do fixed-address/overlay mmap of RAM\n", 898 current->pid); 899 return -EINVAL; 900 } 901 902 if ((flags & MAP_TYPE) != MAP_PRIVATE && 903 (flags & MAP_TYPE) != MAP_SHARED) 904 return -EINVAL; 905 906 if (!len) 907 return -EINVAL; 908 909 /* Careful about overflows.. */ 910 rlen = PAGE_ALIGN(len); 911 if (!rlen || rlen > TASK_SIZE) 912 return -ENOMEM; 913 914 /* offset overflow? */ 915 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) 916 return -EOVERFLOW; 917 918 if (file) { 919 /* validate file mapping requests */ 920 struct address_space *mapping; 921 922 /* files must support mmap */ 923 if (!file->f_op || !file->f_op->mmap) 924 return -ENODEV; 925 926 /* work out if what we've got could possibly be shared 927 * - we support chardevs that provide their own "memory" 928 * - we support files/blockdevs that are memory backed 929 */ 930 mapping = file->f_mapping; 931 if (!mapping) 932 mapping = file->f_path.dentry->d_inode->i_mapping; 933 934 capabilities = 0; 935 if (mapping && mapping->backing_dev_info) 936 capabilities = mapping->backing_dev_info->capabilities; 937 938 if (!capabilities) { 939 /* no explicit capabilities set, so assume some 940 * defaults */ 941 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) { 942 case S_IFREG: 943 case S_IFBLK: 944 capabilities = BDI_CAP_MAP_COPY; 945 break; 946 947 case S_IFCHR: 948 capabilities = 949 BDI_CAP_MAP_DIRECT | 950 BDI_CAP_READ_MAP | 951 BDI_CAP_WRITE_MAP; 952 break; 953 954 default: 955 return -EINVAL; 956 } 957 } 958 959 /* eliminate any capabilities that we can't support on this 960 * device */ 961 if (!file->f_op->get_unmapped_area) 962 capabilities &= ~BDI_CAP_MAP_DIRECT; 963 if (!file->f_op->read) 964 capabilities &= ~BDI_CAP_MAP_COPY; 965 966 /* The file shall have been opened with read permission. */ 967 if (!(file->f_mode & FMODE_READ)) 968 return -EACCES; 969 970 if (flags & MAP_SHARED) { 971 /* do checks for writing, appending and locking */ 972 if ((prot & PROT_WRITE) && 973 !(file->f_mode & FMODE_WRITE)) 974 return -EACCES; 975 976 if (IS_APPEND(file->f_path.dentry->d_inode) && 977 (file->f_mode & FMODE_WRITE)) 978 return -EACCES; 979 980 if (locks_verify_locked(file->f_path.dentry->d_inode)) 981 return -EAGAIN; 982 983 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 984 return -ENODEV; 985 986 /* we mustn't privatise shared mappings */ 987 capabilities &= ~BDI_CAP_MAP_COPY; 988 } 989 else { 990 /* we're going to read the file into private memory we 991 * allocate */ 992 if (!(capabilities & BDI_CAP_MAP_COPY)) 993 return -ENODEV; 994 995 /* we don't permit a private writable mapping to be 996 * shared with the backing device */ 997 if (prot & PROT_WRITE) 998 capabilities &= ~BDI_CAP_MAP_DIRECT; 999 } 1000 1001 if (capabilities & BDI_CAP_MAP_DIRECT) { 1002 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 1003 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 1004 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 1005 ) { 1006 capabilities &= ~BDI_CAP_MAP_DIRECT; 1007 if (flags & MAP_SHARED) { 1008 printk(KERN_WARNING 1009 "MAP_SHARED not completely supported on !MMU\n"); 1010 return -EINVAL; 1011 } 1012 } 1013 } 1014 1015 /* handle executable mappings and implied executable 1016 * mappings */ 1017 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 1018 if (prot & PROT_EXEC) 1019 return -EPERM; 1020 } 1021 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 1022 /* handle implication of PROT_EXEC by PROT_READ */ 1023 if (current->personality & READ_IMPLIES_EXEC) { 1024 if (capabilities & BDI_CAP_EXEC_MAP) 1025 prot |= PROT_EXEC; 1026 } 1027 } 1028 else if ((prot & PROT_READ) && 1029 (prot & PROT_EXEC) && 1030 !(capabilities & BDI_CAP_EXEC_MAP) 1031 ) { 1032 /* backing file is not executable, try to copy */ 1033 capabilities &= ~BDI_CAP_MAP_DIRECT; 1034 } 1035 } 1036 else { 1037 /* anonymous mappings are always memory backed and can be 1038 * privately mapped 1039 */ 1040 capabilities = BDI_CAP_MAP_COPY; 1041 1042 /* handle PROT_EXEC implication by PROT_READ */ 1043 if ((prot & PROT_READ) && 1044 (current->personality & READ_IMPLIES_EXEC)) 1045 prot |= PROT_EXEC; 1046 } 1047 1048 /* allow the security API to have its say */ 1049 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0); 1050 if (ret < 0) 1051 return ret; 1052 1053 /* looks okay */ 1054 *_capabilities = capabilities; 1055 return 0; 1056} 1057 1058/* 1059 * we've determined that we can make the mapping, now translate what we 1060 * now know into VMA flags 1061 */ 1062static unsigned long determine_vm_flags(struct file *file, 1063 unsigned long prot, 1064 unsigned long flags, 1065 unsigned long capabilities) 1066{ 1067 unsigned long vm_flags; 1068 1069 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 1070 /* vm_flags |= mm->def_flags; */ 1071 1072 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 1073 /* attempt to share read-only copies of mapped file chunks */ 1074 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1075 if (file && !(prot & PROT_WRITE)) 1076 vm_flags |= VM_MAYSHARE; 1077 } else { 1078 /* overlay a shareable mapping on the backing device or inode 1079 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 1080 * romfs/cramfs */ 1081 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS); 1082 if (flags & MAP_SHARED) 1083 vm_flags |= VM_SHARED; 1084 } 1085 1086 /* refuse to let anyone share private mappings with this process if 1087 * it's being traced - otherwise breakpoints set in it may interfere 1088 * with another untraced process 1089 */ 1090 if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current)) 1091 vm_flags &= ~VM_MAYSHARE; 1092 1093 return vm_flags; 1094} 1095 1096/* 1097 * set up a shared mapping on a file (the driver or filesystem provides and 1098 * pins the storage) 1099 */ 1100static int do_mmap_shared_file(struct vm_area_struct *vma) 1101{ 1102 int ret; 1103 1104 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1105 if (ret == 0) { 1106 vma->vm_region->vm_top = vma->vm_region->vm_end; 1107 return 0; 1108 } 1109 if (ret != -ENOSYS) 1110 return ret; 1111 1112 /* getting -ENOSYS indicates that direct mmap isn't possible (as 1113 * opposed to tried but failed) so we can only give a suitable error as 1114 * it's not possible to make a private copy if MAP_SHARED was given */ 1115 return -ENODEV; 1116} 1117 1118/* 1119 * set up a private mapping or an anonymous shared mapping 1120 */ 1121static int do_mmap_private(struct vm_area_struct *vma, 1122 struct vm_region *region, 1123 unsigned long len, 1124 unsigned long capabilities) 1125{ 1126 struct page *pages; 1127 unsigned long total, point, n, rlen; 1128 void *base; 1129 int ret, order; 1130 1131 /* invoke the file's mapping function so that it can keep track of 1132 * shared mappings on devices or memory 1133 * - VM_MAYSHARE will be set if it may attempt to share 1134 */ 1135 if (capabilities & BDI_CAP_MAP_DIRECT) { 1136 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1137 if (ret == 0) { 1138 /* shouldn't return success if we're not sharing */ 1139 BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); 1140 vma->vm_region->vm_top = vma->vm_region->vm_end; 1141 return 0; 1142 } 1143 if (ret != -ENOSYS) 1144 return ret; 1145 1146 /* getting an ENOSYS error indicates that direct mmap isn't 1147 * possible (as opposed to tried but failed) so we'll try to 1148 * make a private copy of the data and map that instead */ 1149 } 1150 1151 rlen = PAGE_ALIGN(len); 1152 1153 /* allocate some memory to hold the mapping 1154 * - note that this may not return a page-aligned address if the object 1155 * we're allocating is smaller than a page 1156 */ 1157 order = get_order(rlen); 1158 kdebug("alloc order %d for %lx", order, len); 1159 1160 pages = alloc_pages(GFP_KERNEL, order); 1161 if (!pages) 1162 goto enomem; 1163 1164 total = 1 << order; 1165 atomic_long_add(total, &mmap_pages_allocated); 1166 1167 point = rlen >> PAGE_SHIFT; 1168 1169 /* we allocated a power-of-2 sized page set, so we may want to trim off 1170 * the excess */ 1171 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) { 1172 while (total > point) { 1173 order = ilog2(total - point); 1174 n = 1 << order; 1175 kdebug("shave %lu/%lu @%lu", n, total - point, total); 1176 atomic_long_sub(n, &mmap_pages_allocated); 1177 total -= n; 1178 set_page_refcounted(pages + total); 1179 __free_pages(pages + total, order); 1180 } 1181 } 1182 1183 for (point = 1; point < total; point++) 1184 set_page_refcounted(&pages[point]); 1185 1186 base = page_address(pages); 1187 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; 1188 region->vm_start = (unsigned long) base; 1189 region->vm_end = region->vm_start + rlen; 1190 region->vm_top = region->vm_start + (total << PAGE_SHIFT); 1191 1192 vma->vm_start = region->vm_start; 1193 vma->vm_end = region->vm_start + len; 1194 1195 if (vma->vm_file) { 1196 /* read the contents of a file into the copy */ 1197 mm_segment_t old_fs; 1198 loff_t fpos; 1199 1200 fpos = vma->vm_pgoff; 1201 fpos <<= PAGE_SHIFT; 1202 1203 old_fs = get_fs(); 1204 set_fs(KERNEL_DS); 1205 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos); 1206 set_fs(old_fs); 1207 1208 if (ret < 0) 1209 goto error_free; 1210 1211 /* clear the last little bit */ 1212 if (ret < rlen) 1213 memset(base + ret, 0, rlen - ret); 1214 1215 } 1216 1217 return 0; 1218 1219error_free: 1220 free_page_series(region->vm_start, region->vm_end); 1221 region->vm_start = vma->vm_start = 0; 1222 region->vm_end = vma->vm_end = 0; 1223 region->vm_top = 0; 1224 return ret; 1225 1226enomem: 1227 printk("Allocation of length %lu from process %d (%s) failed\n", 1228 len, current->pid, current->comm); 1229 show_free_areas(0); 1230 return -ENOMEM; 1231} 1232 1233/* 1234 * handle mapping creation for uClinux 1235 */ 1236unsigned long do_mmap_pgoff(struct file *file, 1237 unsigned long addr, 1238 unsigned long len, 1239 unsigned long prot, 1240 unsigned long flags, 1241 unsigned long pgoff) 1242{ 1243 struct vm_area_struct *vma; 1244 struct vm_region *region; 1245 struct rb_node *rb; 1246 unsigned long capabilities, vm_flags, result; 1247 int ret; 1248 1249 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff); 1250 1251 /* decide whether we should attempt the mapping, and if so what sort of 1252 * mapping */ 1253 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 1254 &capabilities); 1255 if (ret < 0) { 1256 kleave(" = %d [val]", ret); 1257 return ret; 1258 } 1259 1260 /* we ignore the address hint */ 1261 addr = 0; 1262 1263 /* we've determined that we can make the mapping, now translate what we 1264 * now know into VMA flags */ 1265 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 1266 1267 /* we're going to need to record the mapping */ 1268 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); 1269 if (!region) 1270 goto error_getting_region; 1271 1272 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1273 if (!vma) 1274 goto error_getting_vma; 1275 1276 region->vm_usage = 1; 1277 region->vm_flags = vm_flags; 1278 region->vm_pgoff = pgoff; 1279 1280 INIT_LIST_HEAD(&vma->anon_vma_chain); 1281 vma->vm_flags = vm_flags; 1282 vma->vm_pgoff = pgoff; 1283 1284 if (file) { 1285 region->vm_file = file; 1286 get_file(file); 1287 vma->vm_file = file; 1288 get_file(file); 1289 if (vm_flags & VM_EXECUTABLE) { 1290 added_exe_file_vma(current->mm); 1291 vma->vm_mm = current->mm; 1292 } 1293 } 1294 1295 down_write(&nommu_region_sem); 1296 1297 /* if we want to share, we need to check for regions created by other 1298 * mmap() calls that overlap with our proposed mapping 1299 * - we can only share with a superset match on most regular files 1300 * - shared mappings on character devices and memory backed files are 1301 * permitted to overlap inexactly as far as we are concerned for in 1302 * these cases, sharing is handled in the driver or filesystem rather 1303 * than here 1304 */ 1305 if (vm_flags & VM_MAYSHARE) { 1306 struct vm_region *pregion; 1307 unsigned long pglen, rpglen, pgend, rpgend, start; 1308 1309 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1310 pgend = pgoff + pglen; 1311 1312 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { 1313 pregion = rb_entry(rb, struct vm_region, vm_rb); 1314 1315 if (!(pregion->vm_flags & VM_MAYSHARE)) 1316 continue; 1317 1318 /* search for overlapping mappings on the same file */ 1319 if (pregion->vm_file->f_path.dentry->d_inode != 1320 file->f_path.dentry->d_inode) 1321 continue; 1322 1323 if (pregion->vm_pgoff >= pgend) 1324 continue; 1325 1326 rpglen = pregion->vm_end - pregion->vm_start; 1327 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1328 rpgend = pregion->vm_pgoff + rpglen; 1329 if (pgoff >= rpgend) 1330 continue; 1331 1332 /* handle inexactly overlapping matches between 1333 * mappings */ 1334 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && 1335 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { 1336 /* new mapping is not a subset of the region */ 1337 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 1338 goto sharing_violation; 1339 continue; 1340 } 1341 1342 /* we've found a region we can share */ 1343 pregion->vm_usage++; 1344 vma->vm_region = pregion; 1345 start = pregion->vm_start; 1346 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; 1347 vma->vm_start = start; 1348 vma->vm_end = start + len; 1349 1350 if (pregion->vm_flags & VM_MAPPED_COPY) { 1351 kdebug("share copy"); 1352 vma->vm_flags |= VM_MAPPED_COPY; 1353 } else { 1354 kdebug("share mmap"); 1355 ret = do_mmap_shared_file(vma); 1356 if (ret < 0) { 1357 vma->vm_region = NULL; 1358 vma->vm_start = 0; 1359 vma->vm_end = 0; 1360 pregion->vm_usage--; 1361 pregion = NULL; 1362 goto error_just_free; 1363 } 1364 } 1365 fput(region->vm_file); 1366 kmem_cache_free(vm_region_jar, region); 1367 region = pregion; 1368 result = start; 1369 goto share; 1370 } 1371 1372 /* obtain the address at which to make a shared mapping 1373 * - this is the hook for quasi-memory character devices to 1374 * tell us the location of a shared mapping 1375 */ 1376 if (capabilities & BDI_CAP_MAP_DIRECT) { 1377 addr = file->f_op->get_unmapped_area(file, addr, len, 1378 pgoff, flags); 1379 if (IS_ERR((void *) addr)) { 1380 ret = addr; 1381 if (ret != (unsigned long) -ENOSYS) 1382 goto error_just_free; 1383 1384 /* the driver refused to tell us where to site 1385 * the mapping so we'll have to attempt to copy 1386 * it */ 1387 ret = (unsigned long) -ENODEV; 1388 if (!(capabilities & BDI_CAP_MAP_COPY)) 1389 goto error_just_free; 1390 1391 capabilities &= ~BDI_CAP_MAP_DIRECT; 1392 } else { 1393 vma->vm_start = region->vm_start = addr; 1394 vma->vm_end = region->vm_end = addr + len; 1395 } 1396 } 1397 } 1398 1399 vma->vm_region = region; 1400 1401 /* set up the mapping 1402 * - the region is filled in if BDI_CAP_MAP_DIRECT is still set 1403 */ 1404 if (file && vma->vm_flags & VM_SHARED) 1405 ret = do_mmap_shared_file(vma); 1406 else 1407 ret = do_mmap_private(vma, region, len, capabilities); 1408 if (ret < 0) 1409 goto error_just_free; 1410 add_nommu_region(region); 1411 1412 /* clear anonymous mappings that don't ask for uninitialized data */ 1413 if (!vma->vm_file && !(flags & MAP_UNINITIALIZED)) 1414 memset((void *)region->vm_start, 0, 1415 region->vm_end - region->vm_start); 1416 1417 /* okay... we have a mapping; now we have to register it */ 1418 result = vma->vm_start; 1419 1420 current->mm->total_vm += len >> PAGE_SHIFT; 1421 1422share: 1423 add_vma_to_mm(current->mm, vma); 1424 1425 /* we flush the region from the icache only when the first executable 1426 * mapping of it is made */ 1427 if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) { 1428 flush_icache_range(region->vm_start, region->vm_end); 1429 region->vm_icache_flushed = true; 1430 } 1431 1432 up_write(&nommu_region_sem); 1433 1434 kleave(" = %lx", result); 1435 return result; 1436 1437error_just_free: 1438 up_write(&nommu_region_sem); 1439error: 1440 if (region->vm_file) 1441 fput(region->vm_file); 1442 kmem_cache_free(vm_region_jar, region); 1443 if (vma->vm_file) 1444 fput(vma->vm_file); 1445 if (vma->vm_flags & VM_EXECUTABLE) 1446 removed_exe_file_vma(vma->vm_mm); 1447 kmem_cache_free(vm_area_cachep, vma); 1448 kleave(" = %d", ret); 1449 return ret; 1450 1451sharing_violation: 1452 up_write(&nommu_region_sem); 1453 printk(KERN_WARNING "Attempt to share mismatched mappings\n"); 1454 ret = -EINVAL; 1455 goto error; 1456 1457error_getting_vma: 1458 kmem_cache_free(vm_region_jar, region); 1459 printk(KERN_WARNING "Allocation of vma for %lu byte allocation" 1460 " from process %d failed\n", 1461 len, current->pid); 1462 show_free_areas(0); 1463 return -ENOMEM; 1464 1465error_getting_region: 1466 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation" 1467 " from process %d failed\n", 1468 len, current->pid); 1469 show_free_areas(0); 1470 return -ENOMEM; 1471} 1472EXPORT_SYMBOL(do_mmap_pgoff); 1473 1474SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len, 1475 unsigned long, prot, unsigned long, flags, 1476 unsigned long, fd, unsigned long, pgoff) 1477{ 1478 struct file *file = NULL; 1479 unsigned long retval = -EBADF; 1480 1481 audit_mmap_fd(fd, flags); 1482 if (!(flags & MAP_ANONYMOUS)) { 1483 file = fget(fd); 1484 if (!file) 1485 goto out; 1486 } 1487 1488 flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE); 1489 1490 down_write(¤t->mm->mmap_sem); 1491 retval = do_mmap_pgoff(file, addr, len, prot, flags, pgoff); 1492 up_write(¤t->mm->mmap_sem); 1493 1494 if (file) 1495 fput(file); 1496out: 1497 return retval; 1498} 1499 1500#ifdef __ARCH_WANT_SYS_OLD_MMAP 1501struct mmap_arg_struct { 1502 unsigned long addr; 1503 unsigned long len; 1504 unsigned long prot; 1505 unsigned long flags; 1506 unsigned long fd; 1507 unsigned long offset; 1508}; 1509 1510SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg) 1511{ 1512 struct mmap_arg_struct a; 1513 1514 if (copy_from_user(&a, arg, sizeof(a))) 1515 return -EFAULT; 1516 if (a.offset & ~PAGE_MASK) 1517 return -EINVAL; 1518 1519 return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, 1520 a.offset >> PAGE_SHIFT); 1521} 1522#endif /* __ARCH_WANT_SYS_OLD_MMAP */ 1523 1524/* 1525 * split a vma into two pieces at address 'addr', a new vma is allocated either 1526 * for the first part or the tail. 1527 */ 1528int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 1529 unsigned long addr, int new_below) 1530{ 1531 struct vm_area_struct *new; 1532 struct vm_region *region; 1533 unsigned long npages; 1534 1535 kenter(""); 1536 1537 /* we're only permitted to split anonymous regions (these should have 1538 * only a single usage on the region) */ 1539 if (vma->vm_file) 1540 return -ENOMEM; 1541 1542 if (mm->map_count >= sysctl_max_map_count) 1543 return -ENOMEM; 1544 1545 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); 1546 if (!region) 1547 return -ENOMEM; 1548 1549 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1550 if (!new) { 1551 kmem_cache_free(vm_region_jar, region); 1552 return -ENOMEM; 1553 } 1554 1555 /* most fields are the same, copy all, and then fixup */ 1556 *new = *vma; 1557 *region = *vma->vm_region; 1558 new->vm_region = region; 1559 1560 npages = (addr - vma->vm_start) >> PAGE_SHIFT; 1561 1562 if (new_below) { 1563 region->vm_top = region->vm_end = new->vm_end = addr; 1564 } else { 1565 region->vm_start = new->vm_start = addr; 1566 region->vm_pgoff = new->vm_pgoff += npages; 1567 } 1568 1569 if (new->vm_ops && new->vm_ops->open) 1570 new->vm_ops->open(new); 1571 1572 delete_vma_from_mm(vma); 1573 down_write(&nommu_region_sem); 1574 delete_nommu_region(vma->vm_region); 1575 if (new_below) { 1576 vma->vm_region->vm_start = vma->vm_start = addr; 1577 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; 1578 } else { 1579 vma->vm_region->vm_end = vma->vm_end = addr; 1580 vma->vm_region->vm_top = addr; 1581 } 1582 add_nommu_region(vma->vm_region); 1583 add_nommu_region(new->vm_region); 1584 up_write(&nommu_region_sem); 1585 add_vma_to_mm(mm, vma); 1586 add_vma_to_mm(mm, new); 1587 return 0; 1588} 1589 1590/* 1591 * shrink a VMA by removing the specified chunk from either the beginning or 1592 * the end 1593 */ 1594static int shrink_vma(struct mm_struct *mm, 1595 struct vm_area_struct *vma, 1596 unsigned long from, unsigned long to) 1597{ 1598 struct vm_region *region; 1599 1600 kenter(""); 1601 1602 /* adjust the VMA's pointers, which may reposition it in the MM's tree 1603 * and list */ 1604 delete_vma_from_mm(vma); 1605 if (from > vma->vm_start) 1606 vma->vm_end = from; 1607 else 1608 vma->vm_start = to; 1609 add_vma_to_mm(mm, vma); 1610 1611 /* cut the backing region down to size */ 1612 region = vma->vm_region; 1613 BUG_ON(region->vm_usage != 1); 1614 1615 down_write(&nommu_region_sem); 1616 delete_nommu_region(region); 1617 if (from > region->vm_start) { 1618 to = region->vm_top; 1619 region->vm_top = region->vm_end = from; 1620 } else { 1621 region->vm_start = to; 1622 } 1623 add_nommu_region(region); 1624 up_write(&nommu_region_sem); 1625 1626 free_page_series(from, to); 1627 return 0; 1628} 1629 1630/* 1631 * release a mapping 1632 * - under NOMMU conditions the chunk to be unmapped must be backed by a single 1633 * VMA, though it need not cover the whole VMA 1634 */ 1635int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1636{ 1637 struct vm_area_struct *vma; 1638 struct rb_node *rb; 1639 unsigned long end = start + len; 1640 int ret; 1641 1642 kenter(",%lx,%zx", start, len); 1643 1644 if (len == 0) 1645 return -EINVAL; 1646 1647 /* find the first potentially overlapping VMA */ 1648 vma = find_vma(mm, start); 1649 if (!vma) { 1650 static int limit = 0; 1651 if (limit < 5) { 1652 printk(KERN_WARNING 1653 "munmap of memory not mmapped by process %d" 1654 " (%s): 0x%lx-0x%lx\n", 1655 current->pid, current->comm, 1656 start, start + len - 1); 1657 limit++; 1658 } 1659 return -EINVAL; 1660 } 1661 1662 /* we're allowed to split an anonymous VMA but not a file-backed one */ 1663 if (vma->vm_file) { 1664 do { 1665 if (start > vma->vm_start) { 1666 kleave(" = -EINVAL [miss]"); 1667 return -EINVAL; 1668 } 1669 if (end == vma->vm_end) 1670 goto erase_whole_vma; 1671 rb = rb_next(&vma->vm_rb); 1672 vma = rb_entry(rb, struct vm_area_struct, vm_rb); 1673 } while (rb); 1674 kleave(" = -EINVAL [split file]"); 1675 return -EINVAL; 1676 } else { 1677 /* the chunk must be a subset of the VMA found */ 1678 if (start == vma->vm_start && end == vma->vm_end) 1679 goto erase_whole_vma; 1680 if (start < vma->vm_start || end > vma->vm_end) { 1681 kleave(" = -EINVAL [superset]"); 1682 return -EINVAL; 1683 } 1684 if (start & ~PAGE_MASK) { 1685 kleave(" = -EINVAL [unaligned start]"); 1686 return -EINVAL; 1687 } 1688 if (end != vma->vm_end && end & ~PAGE_MASK) { 1689 kleave(" = -EINVAL [unaligned split]"); 1690 return -EINVAL; 1691 } 1692 if (start != vma->vm_start && end != vma->vm_end) { 1693 ret = split_vma(mm, vma, start, 1); 1694 if (ret < 0) { 1695 kleave(" = %d [split]", ret); 1696 return ret; 1697 } 1698 } 1699 return shrink_vma(mm, vma, start, end); 1700 } 1701 1702erase_whole_vma: 1703 delete_vma_from_mm(vma); 1704 delete_vma(mm, vma); 1705 kleave(" = 0"); 1706 return 0; 1707} 1708EXPORT_SYMBOL(do_munmap); 1709 1710SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1711{ 1712 int ret; 1713 struct mm_struct *mm = current->mm; 1714 1715 down_write(&mm->mmap_sem); 1716 ret = do_munmap(mm, addr, len); 1717 up_write(&mm->mmap_sem); 1718 return ret; 1719} 1720 1721/* 1722 * release all the mappings made in a process's VM space 1723 */ 1724void exit_mmap(struct mm_struct *mm) 1725{ 1726 struct vm_area_struct *vma; 1727 1728 if (!mm) 1729 return; 1730 1731 kenter(""); 1732 1733 mm->total_vm = 0; 1734 1735 while ((vma = mm->mmap)) { 1736 mm->mmap = vma->vm_next; 1737 delete_vma_from_mm(vma); 1738 delete_vma(mm, vma); 1739 cond_resched(); 1740 } 1741 1742 kleave(""); 1743} 1744 1745unsigned long do_brk(unsigned long addr, unsigned long len) 1746{ 1747 return -ENOMEM; 1748} 1749 1750/* 1751 * expand (or shrink) an existing mapping, potentially moving it at the same 1752 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1753 * 1754 * under NOMMU conditions, we only permit changing a mapping's size, and only 1755 * as long as it stays within the region allocated by do_mmap_private() and the 1756 * block is not shareable 1757 * 1758 * MREMAP_FIXED is not supported under NOMMU conditions 1759 */ 1760unsigned long do_mremap(unsigned long addr, 1761 unsigned long old_len, unsigned long new_len, 1762 unsigned long flags, unsigned long new_addr) 1763{ 1764 struct vm_area_struct *vma; 1765 1766 /* insanity checks first */ 1767 if (old_len == 0 || new_len == 0) 1768 return (unsigned long) -EINVAL; 1769 1770 if (addr & ~PAGE_MASK) 1771 return -EINVAL; 1772 1773 if (flags & MREMAP_FIXED && new_addr != addr) 1774 return (unsigned long) -EINVAL; 1775 1776 vma = find_vma_exact(current->mm, addr, old_len); 1777 if (!vma) 1778 return (unsigned long) -EINVAL; 1779 1780 if (vma->vm_end != vma->vm_start + old_len) 1781 return (unsigned long) -EFAULT; 1782 1783 if (vma->vm_flags & VM_MAYSHARE) 1784 return (unsigned long) -EPERM; 1785 1786 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) 1787 return (unsigned long) -ENOMEM; 1788 1789 /* all checks complete - do it */ 1790 vma->vm_end = vma->vm_start + new_len; 1791 return vma->vm_start; 1792} 1793EXPORT_SYMBOL(do_mremap); 1794 1795SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, 1796 unsigned long, new_len, unsigned long, flags, 1797 unsigned long, new_addr) 1798{ 1799 unsigned long ret; 1800 1801 down_write(¤t->mm->mmap_sem); 1802 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1803 up_write(¤t->mm->mmap_sem); 1804 return ret; 1805} 1806 1807struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1808 unsigned int foll_flags) 1809{ 1810 return NULL; 1811} 1812 1813int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 1814 unsigned long to, unsigned long size, pgprot_t prot) 1815{ 1816 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT; 1817 return 0; 1818} 1819EXPORT_SYMBOL(remap_pfn_range); 1820 1821int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 1822 unsigned long pgoff) 1823{ 1824 unsigned int size = vma->vm_end - vma->vm_start; 1825 1826 if (!(vma->vm_flags & VM_USERMAP)) 1827 return -EINVAL; 1828 1829 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); 1830 vma->vm_end = vma->vm_start + size; 1831 1832 return 0; 1833} 1834EXPORT_SYMBOL(remap_vmalloc_range); 1835 1836unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1837 unsigned long len, unsigned long pgoff, unsigned long flags) 1838{ 1839 return -ENOMEM; 1840} 1841 1842void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1843{ 1844} 1845 1846void unmap_mapping_range(struct address_space *mapping, 1847 loff_t const holebegin, loff_t const holelen, 1848 int even_cows) 1849{ 1850} 1851EXPORT_SYMBOL(unmap_mapping_range); 1852 1853/* 1854 * Check that a process has enough memory to allocate a new virtual 1855 * mapping. 0 means there is enough memory for the allocation to 1856 * succeed and -ENOMEM implies there is not. 1857 * 1858 * We currently support three overcommit policies, which are set via the 1859 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1860 * 1861 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1862 * Additional code 2002 Jul 20 by Robert Love. 1863 * 1864 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1865 * 1866 * Note this is a helper function intended to be used by LSMs which 1867 * wish to use this logic. 1868 */ 1869int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 1870{ 1871 unsigned long free, allowed; 1872 1873 vm_acct_memory(pages); 1874 1875 /* 1876 * Sometimes we want to use more memory than we have 1877 */ 1878 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1879 return 0; 1880 1881 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1882 unsigned long n; 1883 1884 free = global_page_state(NR_FILE_PAGES); 1885 free += nr_swap_pages; 1886 1887 /* 1888 * Any slabs which are created with the 1889 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1890 * which are reclaimable, under pressure. The dentry 1891 * cache and most inode caches should fall into this 1892 */ 1893 free += global_page_state(NR_SLAB_RECLAIMABLE); 1894 1895 /* 1896 * Leave the last 3% for root 1897 */ 1898 if (!cap_sys_admin) 1899 free -= free / 32; 1900 1901 if (free > pages) 1902 return 0; 1903 1904 /* 1905 * nr_free_pages() is very expensive on large systems, 1906 * only call if we're about to fail. 1907 */ 1908 n = nr_free_pages(); 1909 1910 /* 1911 * Leave reserved pages. The pages are not for anonymous pages. 1912 */ 1913 if (n <= totalreserve_pages) 1914 goto error; 1915 else 1916 n -= totalreserve_pages; 1917 1918 /* 1919 * Leave the last 3% for root 1920 */ 1921 if (!cap_sys_admin) 1922 n -= n / 32; 1923 free += n; 1924 1925 if (free > pages) 1926 return 0; 1927 1928 goto error; 1929 } 1930 1931 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1932 /* 1933 * Leave the last 3% for root 1934 */ 1935 if (!cap_sys_admin) 1936 allowed -= allowed / 32; 1937 allowed += total_swap_pages; 1938 1939 /* Don't let a single process grow too big: 1940 leave 3% of the size of this process for other processes */ 1941 if (mm) 1942 allowed -= mm->total_vm / 32; 1943 1944 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 1945 return 0; 1946 1947error: 1948 vm_unacct_memory(pages); 1949 1950 return -ENOMEM; 1951} 1952 1953int in_gate_area_no_mm(unsigned long addr) 1954{ 1955 return 0; 1956} 1957 1958int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1959{ 1960 BUG(); 1961 return 0; 1962} 1963EXPORT_SYMBOL(filemap_fault); 1964 1965static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm, 1966 unsigned long addr, void *buf, int len, int write) 1967{ 1968 struct vm_area_struct *vma; 1969 1970 down_read(&mm->mmap_sem); 1971 1972 /* the access must start within one of the target process's mappings */ 1973 vma = find_vma(mm, addr); 1974 if (vma) { 1975 /* don't overrun this mapping */ 1976 if (addr + len >= vma->vm_end) 1977 len = vma->vm_end - addr; 1978 1979 /* only read or write mappings where it is permitted */ 1980 if (write && vma->vm_flags & VM_MAYWRITE) 1981 copy_to_user_page(vma, NULL, addr, 1982 (void *) addr, buf, len); 1983 else if (!write && vma->vm_flags & VM_MAYREAD) 1984 copy_from_user_page(vma, NULL, addr, 1985 buf, (void *) addr, len); 1986 else 1987 len = 0; 1988 } else { 1989 len = 0; 1990 } 1991 1992 up_read(&mm->mmap_sem); 1993 1994 return len; 1995} 1996 1997/** 1998 * @access_remote_vm - access another process' address space 1999 * @mm: the mm_struct of the target address space 2000 * @addr: start address to access 2001 * @buf: source or destination buffer 2002 * @len: number of bytes to transfer 2003 * @write: whether the access is a write 2004 * 2005 * The caller must hold a reference on @mm. 2006 */ 2007int access_remote_vm(struct mm_struct *mm, unsigned long addr, 2008 void *buf, int len, int write) 2009{ 2010 return __access_remote_vm(NULL, mm, addr, buf, len, write); 2011} 2012 2013/* 2014 * Access another process' address space. 2015 * - source/target buffer must be kernel space 2016 */ 2017int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 2018{ 2019 struct mm_struct *mm; 2020 2021 if (addr + len < addr) 2022 return 0; 2023 2024 mm = get_task_mm(tsk); 2025 if (!mm) 2026 return 0; 2027 2028 len = __access_remote_vm(tsk, mm, addr, buf, len, write); 2029 2030 mmput(mm); 2031 return len; 2032} 2033 2034/** 2035 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode 2036 * @inode: The inode to check 2037 * @size: The current filesize of the inode 2038 * @newsize: The proposed filesize of the inode 2039 * 2040 * Check the shared mappings on an inode on behalf of a shrinking truncate to 2041 * make sure that that any outstanding VMAs aren't broken and then shrink the 2042 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't 2043 * automatically grant mappings that are too large. 2044 */ 2045int nommu_shrink_inode_mappings(struct inode *inode, size_t size, 2046 size_t newsize) 2047{ 2048 struct vm_area_struct *vma; 2049 struct prio_tree_iter iter; 2050 struct vm_region *region; 2051 pgoff_t low, high; 2052 size_t r_size, r_top; 2053 2054 low = newsize >> PAGE_SHIFT; 2055 high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; 2056 2057 down_write(&nommu_region_sem); 2058 2059 /* search for VMAs that fall within the dead zone */ 2060 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap, 2061 low, high) { 2062 /* found one - only interested if it's shared out of the page 2063 * cache */ 2064 if (vma->vm_flags & VM_SHARED) { 2065 up_write(&nommu_region_sem); 2066 return -ETXTBSY; /* not quite true, but near enough */ 2067 } 2068 } 2069 2070 /* reduce any regions that overlap the dead zone - if in existence, 2071 * these will be pointed to by VMAs that don't overlap the dead zone 2072 * 2073 * we don't check for any regions that start beyond the EOF as there 2074 * shouldn't be any 2075 */ 2076 vma_prio_tree_foreach(vma, &iter, &inode->i_mapping->i_mmap, 2077 0, ULONG_MAX) { 2078 if (!(vma->vm_flags & VM_SHARED)) 2079 continue; 2080 2081 region = vma->vm_region; 2082 r_size = region->vm_top - region->vm_start; 2083 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size; 2084 2085 if (r_top > newsize) { 2086 region->vm_top -= r_top - newsize; 2087 if (region->vm_end > region->vm_top) 2088 region->vm_end = region->vm_top; 2089 } 2090 } 2091 2092 up_write(&nommu_region_sem); 2093 return 0; 2094} 2095