nommu.c revision 1c3aff1ceec2cc86810e2690e67873ff0c505862
1/* 2 * linux/mm/nommu.c 3 * 4 * Replacement code for mm functions to support CPU's that don't 5 * have any form of memory management unit (thus no virtual memory). 6 * 7 * See Documentation/nommu-mmap.txt 8 * 9 * Copyright (c) 2004-2008 David Howells <dhowells@redhat.com> 10 * Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com> 11 * Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org> 12 * Copyright (c) 2002 Greg Ungerer <gerg@snapgear.com> 13 * Copyright (c) 2007-2009 Paul Mundt <lethal@linux-sh.org> 14 */ 15 16#include <linux/module.h> 17#include <linux/mm.h> 18#include <linux/mman.h> 19#include <linux/swap.h> 20#include <linux/file.h> 21#include <linux/highmem.h> 22#include <linux/pagemap.h> 23#include <linux/slab.h> 24#include <linux/vmalloc.h> 25#include <linux/tracehook.h> 26#include <linux/blkdev.h> 27#include <linux/backing-dev.h> 28#include <linux/mount.h> 29#include <linux/personality.h> 30#include <linux/security.h> 31#include <linux/syscalls.h> 32 33#include <asm/uaccess.h> 34#include <asm/tlb.h> 35#include <asm/tlbflush.h> 36#include "internal.h" 37 38static inline __attribute__((format(printf, 1, 2))) 39void no_printk(const char *fmt, ...) 40{ 41} 42 43#if 0 44#define kenter(FMT, ...) \ 45 printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 46#define kleave(FMT, ...) \ 47 printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 48#define kdebug(FMT, ...) \ 49 printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__) 50#else 51#define kenter(FMT, ...) \ 52 no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__) 53#define kleave(FMT, ...) \ 54 no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__) 55#define kdebug(FMT, ...) \ 56 no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__) 57#endif 58 59void *high_memory; 60struct page *mem_map; 61unsigned long max_mapnr; 62unsigned long num_physpages; 63struct percpu_counter vm_committed_as; 64int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */ 65int sysctl_overcommit_ratio = 50; /* default is 50% */ 66int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT; 67int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS; 68int heap_stack_gap = 0; 69 70atomic_long_t mmap_pages_allocated; 71 72EXPORT_SYMBOL(mem_map); 73EXPORT_SYMBOL(num_physpages); 74 75/* list of mapped, potentially shareable regions */ 76static struct kmem_cache *vm_region_jar; 77struct rb_root nommu_region_tree = RB_ROOT; 78DECLARE_RWSEM(nommu_region_sem); 79 80struct vm_operations_struct generic_file_vm_ops = { 81}; 82 83/* 84 * Handle all mappings that got truncated by a "truncate()" 85 * system call. 86 * 87 * NOTE! We have to be ready to update the memory sharing 88 * between the file and the memory map for a potential last 89 * incomplete page. Ugly, but necessary. 90 */ 91int vmtruncate(struct inode *inode, loff_t offset) 92{ 93 struct address_space *mapping = inode->i_mapping; 94 unsigned long limit; 95 96 if (inode->i_size < offset) 97 goto do_expand; 98 i_size_write(inode, offset); 99 100 truncate_inode_pages(mapping, offset); 101 goto out_truncate; 102 103do_expand: 104 limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur; 105 if (limit != RLIM_INFINITY && offset > limit) 106 goto out_sig; 107 if (offset > inode->i_sb->s_maxbytes) 108 goto out; 109 i_size_write(inode, offset); 110 111out_truncate: 112 if (inode->i_op->truncate) 113 inode->i_op->truncate(inode); 114 return 0; 115out_sig: 116 send_sig(SIGXFSZ, current, 0); 117out: 118 return -EFBIG; 119} 120 121EXPORT_SYMBOL(vmtruncate); 122 123/* 124 * Return the total memory allocated for this pointer, not 125 * just what the caller asked for. 126 * 127 * Doesn't have to be accurate, i.e. may have races. 128 */ 129unsigned int kobjsize(const void *objp) 130{ 131 struct page *page; 132 133 /* 134 * If the object we have should not have ksize performed on it, 135 * return size of 0 136 */ 137 if (!objp || !virt_addr_valid(objp)) 138 return 0; 139 140 page = virt_to_head_page(objp); 141 142 /* 143 * If the allocator sets PageSlab, we know the pointer came from 144 * kmalloc(). 145 */ 146 if (PageSlab(page)) 147 return ksize(objp); 148 149 /* 150 * If it's not a compound page, see if we have a matching VMA 151 * region. This test is intentionally done in reverse order, 152 * so if there's no VMA, we still fall through and hand back 153 * PAGE_SIZE for 0-order pages. 154 */ 155 if (!PageCompound(page)) { 156 struct vm_area_struct *vma; 157 158 vma = find_vma(current->mm, (unsigned long)objp); 159 if (vma) 160 return vma->vm_end - vma->vm_start; 161 } 162 163 /* 164 * The ksize() function is only guaranteed to work for pointers 165 * returned by kmalloc(). So handle arbitrary pointers here. 166 */ 167 return PAGE_SIZE << compound_order(page); 168} 169 170int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 171 unsigned long start, int nr_pages, int flags, 172 struct page **pages, struct vm_area_struct **vmas) 173{ 174 struct vm_area_struct *vma; 175 unsigned long vm_flags; 176 int i; 177 int write = !!(flags & GUP_FLAGS_WRITE); 178 int force = !!(flags & GUP_FLAGS_FORCE); 179 180 /* calculate required read or write permissions. 181 * - if 'force' is set, we only require the "MAY" flags. 182 */ 183 vm_flags = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD); 184 vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE); 185 186 for (i = 0; i < nr_pages; i++) { 187 vma = find_vma(mm, start); 188 if (!vma) 189 goto finish_or_fault; 190 191 /* protect what we can, including chardevs */ 192 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) || 193 !(vm_flags & vma->vm_flags)) 194 goto finish_or_fault; 195 196 if (pages) { 197 pages[i] = virt_to_page(start); 198 if (pages[i]) 199 page_cache_get(pages[i]); 200 } 201 if (vmas) 202 vmas[i] = vma; 203 start += PAGE_SIZE; 204 } 205 206 return i; 207 208finish_or_fault: 209 return i ? : -EFAULT; 210} 211 212/* 213 * get a list of pages in an address range belonging to the specified process 214 * and indicate the VMA that covers each page 215 * - this is potentially dodgy as we may end incrementing the page count of a 216 * slab page or a secondary page from a compound page 217 * - don't permit access to VMAs that don't support it, such as I/O mappings 218 */ 219int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, 220 unsigned long start, int nr_pages, int write, int force, 221 struct page **pages, struct vm_area_struct **vmas) 222{ 223 int flags = 0; 224 225 if (write) 226 flags |= GUP_FLAGS_WRITE; 227 if (force) 228 flags |= GUP_FLAGS_FORCE; 229 230 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas); 231} 232EXPORT_SYMBOL(get_user_pages); 233 234/** 235 * follow_pfn - look up PFN at a user virtual address 236 * @vma: memory mapping 237 * @address: user virtual address 238 * @pfn: location to store found PFN 239 * 240 * Only IO mappings and raw PFN mappings are allowed. 241 * 242 * Returns zero and the pfn at @pfn on success, -ve otherwise. 243 */ 244int follow_pfn(struct vm_area_struct *vma, unsigned long address, 245 unsigned long *pfn) 246{ 247 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP))) 248 return -EINVAL; 249 250 *pfn = address >> PAGE_SHIFT; 251 return 0; 252} 253EXPORT_SYMBOL(follow_pfn); 254 255DEFINE_RWLOCK(vmlist_lock); 256struct vm_struct *vmlist; 257 258void vfree(const void *addr) 259{ 260 kfree(addr); 261} 262EXPORT_SYMBOL(vfree); 263 264void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot) 265{ 266 /* 267 * You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc() 268 * returns only a logical address. 269 */ 270 return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM); 271} 272EXPORT_SYMBOL(__vmalloc); 273 274void *vmalloc_user(unsigned long size) 275{ 276 void *ret; 277 278 ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, 279 PAGE_KERNEL); 280 if (ret) { 281 struct vm_area_struct *vma; 282 283 down_write(¤t->mm->mmap_sem); 284 vma = find_vma(current->mm, (unsigned long)ret); 285 if (vma) 286 vma->vm_flags |= VM_USERMAP; 287 up_write(¤t->mm->mmap_sem); 288 } 289 290 return ret; 291} 292EXPORT_SYMBOL(vmalloc_user); 293 294struct page *vmalloc_to_page(const void *addr) 295{ 296 return virt_to_page(addr); 297} 298EXPORT_SYMBOL(vmalloc_to_page); 299 300unsigned long vmalloc_to_pfn(const void *addr) 301{ 302 return page_to_pfn(virt_to_page(addr)); 303} 304EXPORT_SYMBOL(vmalloc_to_pfn); 305 306long vread(char *buf, char *addr, unsigned long count) 307{ 308 memcpy(buf, addr, count); 309 return count; 310} 311 312long vwrite(char *buf, char *addr, unsigned long count) 313{ 314 /* Don't allow overflow */ 315 if ((unsigned long) addr + count < count) 316 count = -(unsigned long) addr; 317 318 memcpy(addr, buf, count); 319 return(count); 320} 321 322/* 323 * vmalloc - allocate virtually continguos memory 324 * 325 * @size: allocation size 326 * 327 * Allocate enough pages to cover @size from the page level 328 * allocator and map them into continguos kernel virtual space. 329 * 330 * For tight control over page level allocator and protection flags 331 * use __vmalloc() instead. 332 */ 333void *vmalloc(unsigned long size) 334{ 335 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL); 336} 337EXPORT_SYMBOL(vmalloc); 338 339void *vmalloc_node(unsigned long size, int node) 340{ 341 return vmalloc(size); 342} 343EXPORT_SYMBOL(vmalloc_node); 344 345#ifndef PAGE_KERNEL_EXEC 346# define PAGE_KERNEL_EXEC PAGE_KERNEL 347#endif 348 349/** 350 * vmalloc_exec - allocate virtually contiguous, executable memory 351 * @size: allocation size 352 * 353 * Kernel-internal function to allocate enough pages to cover @size 354 * the page level allocator and map them into contiguous and 355 * executable kernel virtual space. 356 * 357 * For tight control over page level allocator and protection flags 358 * use __vmalloc() instead. 359 */ 360 361void *vmalloc_exec(unsigned long size) 362{ 363 return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC); 364} 365 366/** 367 * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) 368 * @size: allocation size 369 * 370 * Allocate enough 32bit PA addressable pages to cover @size from the 371 * page level allocator and map them into continguos kernel virtual space. 372 */ 373void *vmalloc_32(unsigned long size) 374{ 375 return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL); 376} 377EXPORT_SYMBOL(vmalloc_32); 378 379/** 380 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory 381 * @size: allocation size 382 * 383 * The resulting memory area is 32bit addressable and zeroed so it can be 384 * mapped to userspace without leaking data. 385 * 386 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to 387 * remap_vmalloc_range() are permissible. 388 */ 389void *vmalloc_32_user(unsigned long size) 390{ 391 /* 392 * We'll have to sort out the ZONE_DMA bits for 64-bit, 393 * but for now this can simply use vmalloc_user() directly. 394 */ 395 return vmalloc_user(size); 396} 397EXPORT_SYMBOL(vmalloc_32_user); 398 399void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot) 400{ 401 BUG(); 402 return NULL; 403} 404EXPORT_SYMBOL(vmap); 405 406void vunmap(const void *addr) 407{ 408 BUG(); 409} 410EXPORT_SYMBOL(vunmap); 411 412void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot) 413{ 414 BUG(); 415 return NULL; 416} 417EXPORT_SYMBOL(vm_map_ram); 418 419void vm_unmap_ram(const void *mem, unsigned int count) 420{ 421 BUG(); 422} 423EXPORT_SYMBOL(vm_unmap_ram); 424 425void vm_unmap_aliases(void) 426{ 427} 428EXPORT_SYMBOL_GPL(vm_unmap_aliases); 429 430/* 431 * Implement a stub for vmalloc_sync_all() if the architecture chose not to 432 * have one. 433 */ 434void __attribute__((weak)) vmalloc_sync_all(void) 435{ 436} 437 438int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, 439 struct page *page) 440{ 441 return -EINVAL; 442} 443EXPORT_SYMBOL(vm_insert_page); 444 445/* 446 * sys_brk() for the most part doesn't need the global kernel 447 * lock, except when an application is doing something nasty 448 * like trying to un-brk an area that has already been mapped 449 * to a regular file. in this case, the unmapping will need 450 * to invoke file system routines that need the global lock. 451 */ 452SYSCALL_DEFINE1(brk, unsigned long, brk) 453{ 454 struct mm_struct *mm = current->mm; 455 456 if (brk < mm->start_brk || brk > mm->context.end_brk) 457 return mm->brk; 458 459 if (mm->brk == brk) 460 return mm->brk; 461 462 /* 463 * Always allow shrinking brk 464 */ 465 if (brk <= mm->brk) { 466 mm->brk = brk; 467 return brk; 468 } 469 470 /* 471 * Ok, looks good - let it rip. 472 */ 473 return mm->brk = brk; 474} 475 476/* 477 * initialise the VMA and region record slabs 478 */ 479void __init mmap_init(void) 480{ 481 int ret; 482 483 ret = percpu_counter_init(&vm_committed_as, 0); 484 VM_BUG_ON(ret); 485 vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC); 486} 487 488/* 489 * validate the region tree 490 * - the caller must hold the region lock 491 */ 492#ifdef CONFIG_DEBUG_NOMMU_REGIONS 493static noinline void validate_nommu_regions(void) 494{ 495 struct vm_region *region, *last; 496 struct rb_node *p, *lastp; 497 498 lastp = rb_first(&nommu_region_tree); 499 if (!lastp) 500 return; 501 502 last = rb_entry(lastp, struct vm_region, vm_rb); 503 BUG_ON(unlikely(last->vm_end <= last->vm_start)); 504 BUG_ON(unlikely(last->vm_top < last->vm_end)); 505 506 while ((p = rb_next(lastp))) { 507 region = rb_entry(p, struct vm_region, vm_rb); 508 last = rb_entry(lastp, struct vm_region, vm_rb); 509 510 BUG_ON(unlikely(region->vm_end <= region->vm_start)); 511 BUG_ON(unlikely(region->vm_top < region->vm_end)); 512 BUG_ON(unlikely(region->vm_start < last->vm_top)); 513 514 lastp = p; 515 } 516} 517#else 518static void validate_nommu_regions(void) 519{ 520} 521#endif 522 523/* 524 * add a region into the global tree 525 */ 526static void add_nommu_region(struct vm_region *region) 527{ 528 struct vm_region *pregion; 529 struct rb_node **p, *parent; 530 531 validate_nommu_regions(); 532 533 parent = NULL; 534 p = &nommu_region_tree.rb_node; 535 while (*p) { 536 parent = *p; 537 pregion = rb_entry(parent, struct vm_region, vm_rb); 538 if (region->vm_start < pregion->vm_start) 539 p = &(*p)->rb_left; 540 else if (region->vm_start > pregion->vm_start) 541 p = &(*p)->rb_right; 542 else if (pregion == region) 543 return; 544 else 545 BUG(); 546 } 547 548 rb_link_node(®ion->vm_rb, parent, p); 549 rb_insert_color(®ion->vm_rb, &nommu_region_tree); 550 551 validate_nommu_regions(); 552} 553 554/* 555 * delete a region from the global tree 556 */ 557static void delete_nommu_region(struct vm_region *region) 558{ 559 BUG_ON(!nommu_region_tree.rb_node); 560 561 validate_nommu_regions(); 562 rb_erase(®ion->vm_rb, &nommu_region_tree); 563 validate_nommu_regions(); 564} 565 566/* 567 * free a contiguous series of pages 568 */ 569static void free_page_series(unsigned long from, unsigned long to) 570{ 571 for (; from < to; from += PAGE_SIZE) { 572 struct page *page = virt_to_page(from); 573 574 kdebug("- free %lx", from); 575 atomic_long_dec(&mmap_pages_allocated); 576 if (page_count(page) != 1) 577 kdebug("free page %p: refcount not one: %d", 578 page, page_count(page)); 579 put_page(page); 580 } 581} 582 583/* 584 * release a reference to a region 585 * - the caller must hold the region semaphore for writing, which this releases 586 * - the region may not have been added to the tree yet, in which case vm_top 587 * will equal vm_start 588 */ 589static void __put_nommu_region(struct vm_region *region) 590 __releases(nommu_region_sem) 591{ 592 kenter("%p{%d}", region, atomic_read(®ion->vm_usage)); 593 594 BUG_ON(!nommu_region_tree.rb_node); 595 596 if (atomic_dec_and_test(®ion->vm_usage)) { 597 if (region->vm_top > region->vm_start) 598 delete_nommu_region(region); 599 up_write(&nommu_region_sem); 600 601 if (region->vm_file) 602 fput(region->vm_file); 603 604 /* IO memory and memory shared directly out of the pagecache 605 * from ramfs/tmpfs mustn't be released here */ 606 if (region->vm_flags & VM_MAPPED_COPY) { 607 kdebug("free series"); 608 free_page_series(region->vm_start, region->vm_top); 609 } 610 kmem_cache_free(vm_region_jar, region); 611 } else { 612 up_write(&nommu_region_sem); 613 } 614} 615 616/* 617 * release a reference to a region 618 */ 619static void put_nommu_region(struct vm_region *region) 620{ 621 down_write(&nommu_region_sem); 622 __put_nommu_region(region); 623} 624 625/* 626 * add a VMA into a process's mm_struct in the appropriate place in the list 627 * and tree and add to the address space's page tree also if not an anonymous 628 * page 629 * - should be called with mm->mmap_sem held writelocked 630 */ 631static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma) 632{ 633 struct vm_area_struct *pvma, **pp; 634 struct address_space *mapping; 635 struct rb_node **p, *parent; 636 637 kenter(",%p", vma); 638 639 BUG_ON(!vma->vm_region); 640 641 mm->map_count++; 642 vma->vm_mm = mm; 643 644 /* add the VMA to the mapping */ 645 if (vma->vm_file) { 646 mapping = vma->vm_file->f_mapping; 647 648 flush_dcache_mmap_lock(mapping); 649 vma_prio_tree_insert(vma, &mapping->i_mmap); 650 flush_dcache_mmap_unlock(mapping); 651 } 652 653 /* add the VMA to the tree */ 654 parent = NULL; 655 p = &mm->mm_rb.rb_node; 656 while (*p) { 657 parent = *p; 658 pvma = rb_entry(parent, struct vm_area_struct, vm_rb); 659 660 /* sort by: start addr, end addr, VMA struct addr in that order 661 * (the latter is necessary as we may get identical VMAs) */ 662 if (vma->vm_start < pvma->vm_start) 663 p = &(*p)->rb_left; 664 else if (vma->vm_start > pvma->vm_start) 665 p = &(*p)->rb_right; 666 else if (vma->vm_end < pvma->vm_end) 667 p = &(*p)->rb_left; 668 else if (vma->vm_end > pvma->vm_end) 669 p = &(*p)->rb_right; 670 else if (vma < pvma) 671 p = &(*p)->rb_left; 672 else if (vma > pvma) 673 p = &(*p)->rb_right; 674 else 675 BUG(); 676 } 677 678 rb_link_node(&vma->vm_rb, parent, p); 679 rb_insert_color(&vma->vm_rb, &mm->mm_rb); 680 681 /* add VMA to the VMA list also */ 682 for (pp = &mm->mmap; (pvma = *pp); pp = &(*pp)->vm_next) { 683 if (pvma->vm_start > vma->vm_start) 684 break; 685 if (pvma->vm_start < vma->vm_start) 686 continue; 687 if (pvma->vm_end < vma->vm_end) 688 break; 689 } 690 691 vma->vm_next = *pp; 692 *pp = vma; 693} 694 695/* 696 * delete a VMA from its owning mm_struct and address space 697 */ 698static void delete_vma_from_mm(struct vm_area_struct *vma) 699{ 700 struct vm_area_struct **pp; 701 struct address_space *mapping; 702 struct mm_struct *mm = vma->vm_mm; 703 704 kenter("%p", vma); 705 706 mm->map_count--; 707 if (mm->mmap_cache == vma) 708 mm->mmap_cache = NULL; 709 710 /* remove the VMA from the mapping */ 711 if (vma->vm_file) { 712 mapping = vma->vm_file->f_mapping; 713 714 flush_dcache_mmap_lock(mapping); 715 vma_prio_tree_remove(vma, &mapping->i_mmap); 716 flush_dcache_mmap_unlock(mapping); 717 } 718 719 /* remove from the MM's tree and list */ 720 rb_erase(&vma->vm_rb, &mm->mm_rb); 721 for (pp = &mm->mmap; *pp; pp = &(*pp)->vm_next) { 722 if (*pp == vma) { 723 *pp = vma->vm_next; 724 break; 725 } 726 } 727 728 vma->vm_mm = NULL; 729} 730 731/* 732 * destroy a VMA record 733 */ 734static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma) 735{ 736 kenter("%p", vma); 737 if (vma->vm_ops && vma->vm_ops->close) 738 vma->vm_ops->close(vma); 739 if (vma->vm_file) { 740 fput(vma->vm_file); 741 if (vma->vm_flags & VM_EXECUTABLE) 742 removed_exe_file_vma(mm); 743 } 744 put_nommu_region(vma->vm_region); 745 kmem_cache_free(vm_area_cachep, vma); 746} 747 748/* 749 * look up the first VMA in which addr resides, NULL if none 750 * - should be called with mm->mmap_sem at least held readlocked 751 */ 752struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr) 753{ 754 struct vm_area_struct *vma; 755 struct rb_node *n = mm->mm_rb.rb_node; 756 757 /* check the cache first */ 758 vma = mm->mmap_cache; 759 if (vma && vma->vm_start <= addr && vma->vm_end > addr) 760 return vma; 761 762 /* trawl the tree (there may be multiple mappings in which addr 763 * resides) */ 764 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) { 765 vma = rb_entry(n, struct vm_area_struct, vm_rb); 766 if (vma->vm_start > addr) 767 return NULL; 768 if (vma->vm_end > addr) { 769 mm->mmap_cache = vma; 770 return vma; 771 } 772 } 773 774 return NULL; 775} 776EXPORT_SYMBOL(find_vma); 777 778/* 779 * find a VMA 780 * - we don't extend stack VMAs under NOMMU conditions 781 */ 782struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr) 783{ 784 return find_vma(mm, addr); 785} 786 787/* 788 * expand a stack to a given address 789 * - not supported under NOMMU conditions 790 */ 791int expand_stack(struct vm_area_struct *vma, unsigned long address) 792{ 793 return -ENOMEM; 794} 795 796/* 797 * look up the first VMA exactly that exactly matches addr 798 * - should be called with mm->mmap_sem at least held readlocked 799 */ 800static struct vm_area_struct *find_vma_exact(struct mm_struct *mm, 801 unsigned long addr, 802 unsigned long len) 803{ 804 struct vm_area_struct *vma; 805 struct rb_node *n = mm->mm_rb.rb_node; 806 unsigned long end = addr + len; 807 808 /* check the cache first */ 809 vma = mm->mmap_cache; 810 if (vma && vma->vm_start == addr && vma->vm_end == end) 811 return vma; 812 813 /* trawl the tree (there may be multiple mappings in which addr 814 * resides) */ 815 for (n = rb_first(&mm->mm_rb); n; n = rb_next(n)) { 816 vma = rb_entry(n, struct vm_area_struct, vm_rb); 817 if (vma->vm_start < addr) 818 continue; 819 if (vma->vm_start > addr) 820 return NULL; 821 if (vma->vm_end == end) { 822 mm->mmap_cache = vma; 823 return vma; 824 } 825 } 826 827 return NULL; 828} 829 830/* 831 * determine whether a mapping should be permitted and, if so, what sort of 832 * mapping we're capable of supporting 833 */ 834static int validate_mmap_request(struct file *file, 835 unsigned long addr, 836 unsigned long len, 837 unsigned long prot, 838 unsigned long flags, 839 unsigned long pgoff, 840 unsigned long *_capabilities) 841{ 842 unsigned long capabilities, rlen; 843 unsigned long reqprot = prot; 844 int ret; 845 846 /* do the simple checks first */ 847 if (flags & MAP_FIXED || addr) { 848 printk(KERN_DEBUG 849 "%d: Can't do fixed-address/overlay mmap of RAM\n", 850 current->pid); 851 return -EINVAL; 852 } 853 854 if ((flags & MAP_TYPE) != MAP_PRIVATE && 855 (flags & MAP_TYPE) != MAP_SHARED) 856 return -EINVAL; 857 858 if (!len) 859 return -EINVAL; 860 861 /* Careful about overflows.. */ 862 rlen = PAGE_ALIGN(len); 863 if (!rlen || rlen > TASK_SIZE) 864 return -ENOMEM; 865 866 /* offset overflow? */ 867 if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff) 868 return -EOVERFLOW; 869 870 if (file) { 871 /* validate file mapping requests */ 872 struct address_space *mapping; 873 874 /* files must support mmap */ 875 if (!file->f_op || !file->f_op->mmap) 876 return -ENODEV; 877 878 /* work out if what we've got could possibly be shared 879 * - we support chardevs that provide their own "memory" 880 * - we support files/blockdevs that are memory backed 881 */ 882 mapping = file->f_mapping; 883 if (!mapping) 884 mapping = file->f_path.dentry->d_inode->i_mapping; 885 886 capabilities = 0; 887 if (mapping && mapping->backing_dev_info) 888 capabilities = mapping->backing_dev_info->capabilities; 889 890 if (!capabilities) { 891 /* no explicit capabilities set, so assume some 892 * defaults */ 893 switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) { 894 case S_IFREG: 895 case S_IFBLK: 896 capabilities = BDI_CAP_MAP_COPY; 897 break; 898 899 case S_IFCHR: 900 capabilities = 901 BDI_CAP_MAP_DIRECT | 902 BDI_CAP_READ_MAP | 903 BDI_CAP_WRITE_MAP; 904 break; 905 906 default: 907 return -EINVAL; 908 } 909 } 910 911 /* eliminate any capabilities that we can't support on this 912 * device */ 913 if (!file->f_op->get_unmapped_area) 914 capabilities &= ~BDI_CAP_MAP_DIRECT; 915 if (!file->f_op->read) 916 capabilities &= ~BDI_CAP_MAP_COPY; 917 918 /* The file shall have been opened with read permission. */ 919 if (!(file->f_mode & FMODE_READ)) 920 return -EACCES; 921 922 if (flags & MAP_SHARED) { 923 /* do checks for writing, appending and locking */ 924 if ((prot & PROT_WRITE) && 925 !(file->f_mode & FMODE_WRITE)) 926 return -EACCES; 927 928 if (IS_APPEND(file->f_path.dentry->d_inode) && 929 (file->f_mode & FMODE_WRITE)) 930 return -EACCES; 931 932 if (locks_verify_locked(file->f_path.dentry->d_inode)) 933 return -EAGAIN; 934 935 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 936 return -ENODEV; 937 938 if (((prot & PROT_READ) && !(capabilities & BDI_CAP_READ_MAP)) || 939 ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) || 940 ((prot & PROT_EXEC) && !(capabilities & BDI_CAP_EXEC_MAP)) 941 ) { 942 printk("MAP_SHARED not completely supported on !MMU\n"); 943 return -EINVAL; 944 } 945 946 /* we mustn't privatise shared mappings */ 947 capabilities &= ~BDI_CAP_MAP_COPY; 948 } 949 else { 950 /* we're going to read the file into private memory we 951 * allocate */ 952 if (!(capabilities & BDI_CAP_MAP_COPY)) 953 return -ENODEV; 954 955 /* we don't permit a private writable mapping to be 956 * shared with the backing device */ 957 if (prot & PROT_WRITE) 958 capabilities &= ~BDI_CAP_MAP_DIRECT; 959 } 960 961 /* handle executable mappings and implied executable 962 * mappings */ 963 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) { 964 if (prot & PROT_EXEC) 965 return -EPERM; 966 } 967 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) { 968 /* handle implication of PROT_EXEC by PROT_READ */ 969 if (current->personality & READ_IMPLIES_EXEC) { 970 if (capabilities & BDI_CAP_EXEC_MAP) 971 prot |= PROT_EXEC; 972 } 973 } 974 else if ((prot & PROT_READ) && 975 (prot & PROT_EXEC) && 976 !(capabilities & BDI_CAP_EXEC_MAP) 977 ) { 978 /* backing file is not executable, try to copy */ 979 capabilities &= ~BDI_CAP_MAP_DIRECT; 980 } 981 } 982 else { 983 /* anonymous mappings are always memory backed and can be 984 * privately mapped 985 */ 986 capabilities = BDI_CAP_MAP_COPY; 987 988 /* handle PROT_EXEC implication by PROT_READ */ 989 if ((prot & PROT_READ) && 990 (current->personality & READ_IMPLIES_EXEC)) 991 prot |= PROT_EXEC; 992 } 993 994 /* allow the security API to have its say */ 995 ret = security_file_mmap(file, reqprot, prot, flags, addr, 0); 996 if (ret < 0) 997 return ret; 998 999 /* looks okay */ 1000 *_capabilities = capabilities; 1001 return 0; 1002} 1003 1004/* 1005 * we've determined that we can make the mapping, now translate what we 1006 * now know into VMA flags 1007 */ 1008static unsigned long determine_vm_flags(struct file *file, 1009 unsigned long prot, 1010 unsigned long flags, 1011 unsigned long capabilities) 1012{ 1013 unsigned long vm_flags; 1014 1015 vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags); 1016 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC; 1017 /* vm_flags |= mm->def_flags; */ 1018 1019 if (!(capabilities & BDI_CAP_MAP_DIRECT)) { 1020 /* attempt to share read-only copies of mapped file chunks */ 1021 if (file && !(prot & PROT_WRITE)) 1022 vm_flags |= VM_MAYSHARE; 1023 } 1024 else { 1025 /* overlay a shareable mapping on the backing device or inode 1026 * if possible - used for chardevs, ramfs/tmpfs/shmfs and 1027 * romfs/cramfs */ 1028 if (flags & MAP_SHARED) 1029 vm_flags |= VM_MAYSHARE | VM_SHARED; 1030 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0) 1031 vm_flags |= VM_MAYSHARE; 1032 } 1033 1034 /* refuse to let anyone share private mappings with this process if 1035 * it's being traced - otherwise breakpoints set in it may interfere 1036 * with another untraced process 1037 */ 1038 if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current)) 1039 vm_flags &= ~VM_MAYSHARE; 1040 1041 return vm_flags; 1042} 1043 1044/* 1045 * set up a shared mapping on a file (the driver or filesystem provides and 1046 * pins the storage) 1047 */ 1048static int do_mmap_shared_file(struct vm_area_struct *vma) 1049{ 1050 int ret; 1051 1052 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1053 if (ret == 0) { 1054 vma->vm_region->vm_top = vma->vm_region->vm_end; 1055 return ret; 1056 } 1057 if (ret != -ENOSYS) 1058 return ret; 1059 1060 /* getting an ENOSYS error indicates that direct mmap isn't 1061 * possible (as opposed to tried but failed) so we'll fall 1062 * through to making a private copy of the data and mapping 1063 * that if we can */ 1064 return -ENODEV; 1065} 1066 1067/* 1068 * set up a private mapping or an anonymous shared mapping 1069 */ 1070static int do_mmap_private(struct vm_area_struct *vma, 1071 struct vm_region *region, 1072 unsigned long len) 1073{ 1074 struct page *pages; 1075 unsigned long total, point, n, rlen; 1076 void *base; 1077 int ret, order; 1078 1079 /* invoke the file's mapping function so that it can keep track of 1080 * shared mappings on devices or memory 1081 * - VM_MAYSHARE will be set if it may attempt to share 1082 */ 1083 if (vma->vm_file) { 1084 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma); 1085 if (ret == 0) { 1086 /* shouldn't return success if we're not sharing */ 1087 BUG_ON(!(vma->vm_flags & VM_MAYSHARE)); 1088 vma->vm_region->vm_top = vma->vm_region->vm_end; 1089 return ret; 1090 } 1091 if (ret != -ENOSYS) 1092 return ret; 1093 1094 /* getting an ENOSYS error indicates that direct mmap isn't 1095 * possible (as opposed to tried but failed) so we'll try to 1096 * make a private copy of the data and map that instead */ 1097 } 1098 1099 rlen = PAGE_ALIGN(len); 1100 1101 /* allocate some memory to hold the mapping 1102 * - note that this may not return a page-aligned address if the object 1103 * we're allocating is smaller than a page 1104 */ 1105 order = get_order(rlen); 1106 kdebug("alloc order %d for %lx", order, len); 1107 1108 pages = alloc_pages(GFP_KERNEL, order); 1109 if (!pages) 1110 goto enomem; 1111 1112 total = 1 << order; 1113 atomic_long_add(total, &mmap_pages_allocated); 1114 1115 point = rlen >> PAGE_SHIFT; 1116 1117 /* we allocated a power-of-2 sized page set, so we may want to trim off 1118 * the excess */ 1119 if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) { 1120 while (total > point) { 1121 order = ilog2(total - point); 1122 n = 1 << order; 1123 kdebug("shave %lu/%lu @%lu", n, total - point, total); 1124 atomic_long_sub(n, &mmap_pages_allocated); 1125 total -= n; 1126 set_page_refcounted(pages + total); 1127 __free_pages(pages + total, order); 1128 } 1129 } 1130 1131 for (point = 1; point < total; point++) 1132 set_page_refcounted(&pages[point]); 1133 1134 base = page_address(pages); 1135 region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY; 1136 region->vm_start = (unsigned long) base; 1137 region->vm_end = region->vm_start + rlen; 1138 region->vm_top = region->vm_start + (total << PAGE_SHIFT); 1139 1140 vma->vm_start = region->vm_start; 1141 vma->vm_end = region->vm_start + len; 1142 1143 if (vma->vm_file) { 1144 /* read the contents of a file into the copy */ 1145 mm_segment_t old_fs; 1146 loff_t fpos; 1147 1148 fpos = vma->vm_pgoff; 1149 fpos <<= PAGE_SHIFT; 1150 1151 old_fs = get_fs(); 1152 set_fs(KERNEL_DS); 1153 ret = vma->vm_file->f_op->read(vma->vm_file, base, rlen, &fpos); 1154 set_fs(old_fs); 1155 1156 if (ret < 0) 1157 goto error_free; 1158 1159 /* clear the last little bit */ 1160 if (ret < rlen) 1161 memset(base + ret, 0, rlen - ret); 1162 1163 } else { 1164 /* if it's an anonymous mapping, then just clear it */ 1165 memset(base, 0, rlen); 1166 } 1167 1168 return 0; 1169 1170error_free: 1171 free_page_series(region->vm_start, region->vm_end); 1172 region->vm_start = vma->vm_start = 0; 1173 region->vm_end = vma->vm_end = 0; 1174 region->vm_top = 0; 1175 return ret; 1176 1177enomem: 1178 printk("Allocation of length %lu from process %d (%s) failed\n", 1179 len, current->pid, current->comm); 1180 show_free_areas(); 1181 return -ENOMEM; 1182} 1183 1184/* 1185 * handle mapping creation for uClinux 1186 */ 1187unsigned long do_mmap_pgoff(struct file *file, 1188 unsigned long addr, 1189 unsigned long len, 1190 unsigned long prot, 1191 unsigned long flags, 1192 unsigned long pgoff) 1193{ 1194 struct vm_area_struct *vma; 1195 struct vm_region *region; 1196 struct rb_node *rb; 1197 unsigned long capabilities, vm_flags, result; 1198 int ret; 1199 1200 kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff); 1201 1202 if (!(flags & MAP_FIXED)) 1203 addr = round_hint_to_min(addr); 1204 1205 /* decide whether we should attempt the mapping, and if so what sort of 1206 * mapping */ 1207 ret = validate_mmap_request(file, addr, len, prot, flags, pgoff, 1208 &capabilities); 1209 if (ret < 0) { 1210 kleave(" = %d [val]", ret); 1211 return ret; 1212 } 1213 1214 /* we've determined that we can make the mapping, now translate what we 1215 * now know into VMA flags */ 1216 vm_flags = determine_vm_flags(file, prot, flags, capabilities); 1217 1218 /* we're going to need to record the mapping */ 1219 region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL); 1220 if (!region) 1221 goto error_getting_region; 1222 1223 vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL); 1224 if (!vma) 1225 goto error_getting_vma; 1226 1227 atomic_set(®ion->vm_usage, 1); 1228 region->vm_flags = vm_flags; 1229 region->vm_pgoff = pgoff; 1230 1231 INIT_LIST_HEAD(&vma->anon_vma_node); 1232 vma->vm_flags = vm_flags; 1233 vma->vm_pgoff = pgoff; 1234 1235 if (file) { 1236 region->vm_file = file; 1237 get_file(file); 1238 vma->vm_file = file; 1239 get_file(file); 1240 if (vm_flags & VM_EXECUTABLE) { 1241 added_exe_file_vma(current->mm); 1242 vma->vm_mm = current->mm; 1243 } 1244 } 1245 1246 down_write(&nommu_region_sem); 1247 1248 /* if we want to share, we need to check for regions created by other 1249 * mmap() calls that overlap with our proposed mapping 1250 * - we can only share with a superset match on most regular files 1251 * - shared mappings on character devices and memory backed files are 1252 * permitted to overlap inexactly as far as we are concerned for in 1253 * these cases, sharing is handled in the driver or filesystem rather 1254 * than here 1255 */ 1256 if (vm_flags & VM_MAYSHARE) { 1257 struct vm_region *pregion; 1258 unsigned long pglen, rpglen, pgend, rpgend, start; 1259 1260 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; 1261 pgend = pgoff + pglen; 1262 1263 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) { 1264 pregion = rb_entry(rb, struct vm_region, vm_rb); 1265 1266 if (!(pregion->vm_flags & VM_MAYSHARE)) 1267 continue; 1268 1269 /* search for overlapping mappings on the same file */ 1270 if (pregion->vm_file->f_path.dentry->d_inode != 1271 file->f_path.dentry->d_inode) 1272 continue; 1273 1274 if (pregion->vm_pgoff >= pgend) 1275 continue; 1276 1277 rpglen = pregion->vm_end - pregion->vm_start; 1278 rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT; 1279 rpgend = pregion->vm_pgoff + rpglen; 1280 if (pgoff >= rpgend) 1281 continue; 1282 1283 /* handle inexactly overlapping matches between 1284 * mappings */ 1285 if ((pregion->vm_pgoff != pgoff || rpglen != pglen) && 1286 !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) { 1287 /* new mapping is not a subset of the region */ 1288 if (!(capabilities & BDI_CAP_MAP_DIRECT)) 1289 goto sharing_violation; 1290 continue; 1291 } 1292 1293 /* we've found a region we can share */ 1294 atomic_inc(&pregion->vm_usage); 1295 vma->vm_region = pregion; 1296 start = pregion->vm_start; 1297 start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT; 1298 vma->vm_start = start; 1299 vma->vm_end = start + len; 1300 1301 if (pregion->vm_flags & VM_MAPPED_COPY) { 1302 kdebug("share copy"); 1303 vma->vm_flags |= VM_MAPPED_COPY; 1304 } else { 1305 kdebug("share mmap"); 1306 ret = do_mmap_shared_file(vma); 1307 if (ret < 0) { 1308 vma->vm_region = NULL; 1309 vma->vm_start = 0; 1310 vma->vm_end = 0; 1311 atomic_dec(&pregion->vm_usage); 1312 pregion = NULL; 1313 goto error_just_free; 1314 } 1315 } 1316 fput(region->vm_file); 1317 kmem_cache_free(vm_region_jar, region); 1318 region = pregion; 1319 result = start; 1320 goto share; 1321 } 1322 1323 /* obtain the address at which to make a shared mapping 1324 * - this is the hook for quasi-memory character devices to 1325 * tell us the location of a shared mapping 1326 */ 1327 if (file && file->f_op->get_unmapped_area) { 1328 addr = file->f_op->get_unmapped_area(file, addr, len, 1329 pgoff, flags); 1330 if (IS_ERR((void *) addr)) { 1331 ret = addr; 1332 if (ret != (unsigned long) -ENOSYS) 1333 goto error_just_free; 1334 1335 /* the driver refused to tell us where to site 1336 * the mapping so we'll have to attempt to copy 1337 * it */ 1338 ret = (unsigned long) -ENODEV; 1339 if (!(capabilities & BDI_CAP_MAP_COPY)) 1340 goto error_just_free; 1341 1342 capabilities &= ~BDI_CAP_MAP_DIRECT; 1343 } else { 1344 vma->vm_start = region->vm_start = addr; 1345 vma->vm_end = region->vm_end = addr + len; 1346 } 1347 } 1348 } 1349 1350 vma->vm_region = region; 1351 add_nommu_region(region); 1352 1353 /* set up the mapping */ 1354 if (file && vma->vm_flags & VM_SHARED) 1355 ret = do_mmap_shared_file(vma); 1356 else 1357 ret = do_mmap_private(vma, region, len); 1358 if (ret < 0) 1359 goto error_put_region; 1360 1361 /* okay... we have a mapping; now we have to register it */ 1362 result = vma->vm_start; 1363 1364 current->mm->total_vm += len >> PAGE_SHIFT; 1365 1366share: 1367 add_vma_to_mm(current->mm, vma); 1368 1369 up_write(&nommu_region_sem); 1370 1371 if (prot & PROT_EXEC) 1372 flush_icache_range(result, result + len); 1373 1374 kleave(" = %lx", result); 1375 return result; 1376 1377error_put_region: 1378 __put_nommu_region(region); 1379 if (vma) { 1380 if (vma->vm_file) { 1381 fput(vma->vm_file); 1382 if (vma->vm_flags & VM_EXECUTABLE) 1383 removed_exe_file_vma(vma->vm_mm); 1384 } 1385 kmem_cache_free(vm_area_cachep, vma); 1386 } 1387 kleave(" = %d [pr]", ret); 1388 return ret; 1389 1390error_just_free: 1391 up_write(&nommu_region_sem); 1392error: 1393 fput(region->vm_file); 1394 kmem_cache_free(vm_region_jar, region); 1395 fput(vma->vm_file); 1396 if (vma->vm_flags & VM_EXECUTABLE) 1397 removed_exe_file_vma(vma->vm_mm); 1398 kmem_cache_free(vm_area_cachep, vma); 1399 kleave(" = %d", ret); 1400 return ret; 1401 1402sharing_violation: 1403 up_write(&nommu_region_sem); 1404 printk(KERN_WARNING "Attempt to share mismatched mappings\n"); 1405 ret = -EINVAL; 1406 goto error; 1407 1408error_getting_vma: 1409 kmem_cache_free(vm_region_jar, region); 1410 printk(KERN_WARNING "Allocation of vma for %lu byte allocation" 1411 " from process %d failed\n", 1412 len, current->pid); 1413 show_free_areas(); 1414 return -ENOMEM; 1415 1416error_getting_region: 1417 printk(KERN_WARNING "Allocation of vm region for %lu byte allocation" 1418 " from process %d failed\n", 1419 len, current->pid); 1420 show_free_areas(); 1421 return -ENOMEM; 1422} 1423EXPORT_SYMBOL(do_mmap_pgoff); 1424 1425/* 1426 * split a vma into two pieces at address 'addr', a new vma is allocated either 1427 * for the first part or the tail. 1428 */ 1429int split_vma(struct mm_struct *mm, struct vm_area_struct *vma, 1430 unsigned long addr, int new_below) 1431{ 1432 struct vm_area_struct *new; 1433 struct vm_region *region; 1434 unsigned long npages; 1435 1436 kenter(""); 1437 1438 /* we're only permitted to split anonymous regions that have a single 1439 * owner */ 1440 if (vma->vm_file || 1441 atomic_read(&vma->vm_region->vm_usage) != 1) 1442 return -ENOMEM; 1443 1444 if (mm->map_count >= sysctl_max_map_count) 1445 return -ENOMEM; 1446 1447 region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL); 1448 if (!region) 1449 return -ENOMEM; 1450 1451 new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL); 1452 if (!new) { 1453 kmem_cache_free(vm_region_jar, region); 1454 return -ENOMEM; 1455 } 1456 1457 /* most fields are the same, copy all, and then fixup */ 1458 *new = *vma; 1459 *region = *vma->vm_region; 1460 new->vm_region = region; 1461 1462 npages = (addr - vma->vm_start) >> PAGE_SHIFT; 1463 1464 if (new_below) { 1465 region->vm_top = region->vm_end = new->vm_end = addr; 1466 } else { 1467 region->vm_start = new->vm_start = addr; 1468 region->vm_pgoff = new->vm_pgoff += npages; 1469 } 1470 1471 if (new->vm_ops && new->vm_ops->open) 1472 new->vm_ops->open(new); 1473 1474 delete_vma_from_mm(vma); 1475 down_write(&nommu_region_sem); 1476 delete_nommu_region(vma->vm_region); 1477 if (new_below) { 1478 vma->vm_region->vm_start = vma->vm_start = addr; 1479 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages; 1480 } else { 1481 vma->vm_region->vm_end = vma->vm_end = addr; 1482 vma->vm_region->vm_top = addr; 1483 } 1484 add_nommu_region(vma->vm_region); 1485 add_nommu_region(new->vm_region); 1486 up_write(&nommu_region_sem); 1487 add_vma_to_mm(mm, vma); 1488 add_vma_to_mm(mm, new); 1489 return 0; 1490} 1491 1492/* 1493 * shrink a VMA by removing the specified chunk from either the beginning or 1494 * the end 1495 */ 1496static int shrink_vma(struct mm_struct *mm, 1497 struct vm_area_struct *vma, 1498 unsigned long from, unsigned long to) 1499{ 1500 struct vm_region *region; 1501 1502 kenter(""); 1503 1504 /* adjust the VMA's pointers, which may reposition it in the MM's tree 1505 * and list */ 1506 delete_vma_from_mm(vma); 1507 if (from > vma->vm_start) 1508 vma->vm_end = from; 1509 else 1510 vma->vm_start = to; 1511 add_vma_to_mm(mm, vma); 1512 1513 /* cut the backing region down to size */ 1514 region = vma->vm_region; 1515 BUG_ON(atomic_read(®ion->vm_usage) != 1); 1516 1517 down_write(&nommu_region_sem); 1518 delete_nommu_region(region); 1519 if (from > region->vm_start) { 1520 to = region->vm_top; 1521 region->vm_top = region->vm_end = from; 1522 } else { 1523 region->vm_start = to; 1524 } 1525 add_nommu_region(region); 1526 up_write(&nommu_region_sem); 1527 1528 free_page_series(from, to); 1529 return 0; 1530} 1531 1532/* 1533 * release a mapping 1534 * - under NOMMU conditions the chunk to be unmapped must be backed by a single 1535 * VMA, though it need not cover the whole VMA 1536 */ 1537int do_munmap(struct mm_struct *mm, unsigned long start, size_t len) 1538{ 1539 struct vm_area_struct *vma; 1540 struct rb_node *rb; 1541 unsigned long end = start + len; 1542 int ret; 1543 1544 kenter(",%lx,%zx", start, len); 1545 1546 if (len == 0) 1547 return -EINVAL; 1548 1549 /* find the first potentially overlapping VMA */ 1550 vma = find_vma(mm, start); 1551 if (!vma) { 1552 static int limit = 0; 1553 if (limit < 5) { 1554 printk(KERN_WARNING 1555 "munmap of memory not mmapped by process %d" 1556 " (%s): 0x%lx-0x%lx\n", 1557 current->pid, current->comm, 1558 start, start + len - 1); 1559 limit++; 1560 } 1561 return -EINVAL; 1562 } 1563 1564 /* we're allowed to split an anonymous VMA but not a file-backed one */ 1565 if (vma->vm_file) { 1566 do { 1567 if (start > vma->vm_start) { 1568 kleave(" = -EINVAL [miss]"); 1569 return -EINVAL; 1570 } 1571 if (end == vma->vm_end) 1572 goto erase_whole_vma; 1573 rb = rb_next(&vma->vm_rb); 1574 vma = rb_entry(rb, struct vm_area_struct, vm_rb); 1575 } while (rb); 1576 kleave(" = -EINVAL [split file]"); 1577 return -EINVAL; 1578 } else { 1579 /* the chunk must be a subset of the VMA found */ 1580 if (start == vma->vm_start && end == vma->vm_end) 1581 goto erase_whole_vma; 1582 if (start < vma->vm_start || end > vma->vm_end) { 1583 kleave(" = -EINVAL [superset]"); 1584 return -EINVAL; 1585 } 1586 if (start & ~PAGE_MASK) { 1587 kleave(" = -EINVAL [unaligned start]"); 1588 return -EINVAL; 1589 } 1590 if (end != vma->vm_end && end & ~PAGE_MASK) { 1591 kleave(" = -EINVAL [unaligned split]"); 1592 return -EINVAL; 1593 } 1594 if (start != vma->vm_start && end != vma->vm_end) { 1595 ret = split_vma(mm, vma, start, 1); 1596 if (ret < 0) { 1597 kleave(" = %d [split]", ret); 1598 return ret; 1599 } 1600 } 1601 return shrink_vma(mm, vma, start, end); 1602 } 1603 1604erase_whole_vma: 1605 delete_vma_from_mm(vma); 1606 delete_vma(mm, vma); 1607 kleave(" = 0"); 1608 return 0; 1609} 1610EXPORT_SYMBOL(do_munmap); 1611 1612SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len) 1613{ 1614 int ret; 1615 struct mm_struct *mm = current->mm; 1616 1617 down_write(&mm->mmap_sem); 1618 ret = do_munmap(mm, addr, len); 1619 up_write(&mm->mmap_sem); 1620 return ret; 1621} 1622 1623/* 1624 * release all the mappings made in a process's VM space 1625 */ 1626void exit_mmap(struct mm_struct *mm) 1627{ 1628 struct vm_area_struct *vma; 1629 1630 if (!mm) 1631 return; 1632 1633 kenter(""); 1634 1635 mm->total_vm = 0; 1636 1637 while ((vma = mm->mmap)) { 1638 mm->mmap = vma->vm_next; 1639 delete_vma_from_mm(vma); 1640 delete_vma(mm, vma); 1641 } 1642 1643 kleave(""); 1644} 1645 1646unsigned long do_brk(unsigned long addr, unsigned long len) 1647{ 1648 return -ENOMEM; 1649} 1650 1651/* 1652 * expand (or shrink) an existing mapping, potentially moving it at the same 1653 * time (controlled by the MREMAP_MAYMOVE flag and available VM space) 1654 * 1655 * under NOMMU conditions, we only permit changing a mapping's size, and only 1656 * as long as it stays within the region allocated by do_mmap_private() and the 1657 * block is not shareable 1658 * 1659 * MREMAP_FIXED is not supported under NOMMU conditions 1660 */ 1661unsigned long do_mremap(unsigned long addr, 1662 unsigned long old_len, unsigned long new_len, 1663 unsigned long flags, unsigned long new_addr) 1664{ 1665 struct vm_area_struct *vma; 1666 1667 /* insanity checks first */ 1668 if (old_len == 0 || new_len == 0) 1669 return (unsigned long) -EINVAL; 1670 1671 if (addr & ~PAGE_MASK) 1672 return -EINVAL; 1673 1674 if (flags & MREMAP_FIXED && new_addr != addr) 1675 return (unsigned long) -EINVAL; 1676 1677 vma = find_vma_exact(current->mm, addr, old_len); 1678 if (!vma) 1679 return (unsigned long) -EINVAL; 1680 1681 if (vma->vm_end != vma->vm_start + old_len) 1682 return (unsigned long) -EFAULT; 1683 1684 if (vma->vm_flags & VM_MAYSHARE) 1685 return (unsigned long) -EPERM; 1686 1687 if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start) 1688 return (unsigned long) -ENOMEM; 1689 1690 /* all checks complete - do it */ 1691 vma->vm_end = vma->vm_start + new_len; 1692 return vma->vm_start; 1693} 1694EXPORT_SYMBOL(do_mremap); 1695 1696SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, 1697 unsigned long, new_len, unsigned long, flags, 1698 unsigned long, new_addr) 1699{ 1700 unsigned long ret; 1701 1702 down_write(¤t->mm->mmap_sem); 1703 ret = do_mremap(addr, old_len, new_len, flags, new_addr); 1704 up_write(¤t->mm->mmap_sem); 1705 return ret; 1706} 1707 1708struct page *follow_page(struct vm_area_struct *vma, unsigned long address, 1709 unsigned int foll_flags) 1710{ 1711 return NULL; 1712} 1713 1714int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, 1715 unsigned long to, unsigned long size, pgprot_t prot) 1716{ 1717 vma->vm_start = vma->vm_pgoff << PAGE_SHIFT; 1718 return 0; 1719} 1720EXPORT_SYMBOL(remap_pfn_range); 1721 1722int remap_vmalloc_range(struct vm_area_struct *vma, void *addr, 1723 unsigned long pgoff) 1724{ 1725 unsigned int size = vma->vm_end - vma->vm_start; 1726 1727 if (!(vma->vm_flags & VM_USERMAP)) 1728 return -EINVAL; 1729 1730 vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT)); 1731 vma->vm_end = vma->vm_start + size; 1732 1733 return 0; 1734} 1735EXPORT_SYMBOL(remap_vmalloc_range); 1736 1737void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page) 1738{ 1739} 1740 1741unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr, 1742 unsigned long len, unsigned long pgoff, unsigned long flags) 1743{ 1744 return -ENOMEM; 1745} 1746 1747void arch_unmap_area(struct mm_struct *mm, unsigned long addr) 1748{ 1749} 1750 1751void unmap_mapping_range(struct address_space *mapping, 1752 loff_t const holebegin, loff_t const holelen, 1753 int even_cows) 1754{ 1755} 1756EXPORT_SYMBOL(unmap_mapping_range); 1757 1758/* 1759 * ask for an unmapped area at which to create a mapping on a file 1760 */ 1761unsigned long get_unmapped_area(struct file *file, unsigned long addr, 1762 unsigned long len, unsigned long pgoff, 1763 unsigned long flags) 1764{ 1765 unsigned long (*get_area)(struct file *, unsigned long, unsigned long, 1766 unsigned long, unsigned long); 1767 1768 get_area = current->mm->get_unmapped_area; 1769 if (file && file->f_op && file->f_op->get_unmapped_area) 1770 get_area = file->f_op->get_unmapped_area; 1771 1772 if (!get_area) 1773 return -ENOSYS; 1774 1775 return get_area(file, addr, len, pgoff, flags); 1776} 1777EXPORT_SYMBOL(get_unmapped_area); 1778 1779/* 1780 * Check that a process has enough memory to allocate a new virtual 1781 * mapping. 0 means there is enough memory for the allocation to 1782 * succeed and -ENOMEM implies there is not. 1783 * 1784 * We currently support three overcommit policies, which are set via the 1785 * vm.overcommit_memory sysctl. See Documentation/vm/overcommit-accounting 1786 * 1787 * Strict overcommit modes added 2002 Feb 26 by Alan Cox. 1788 * Additional code 2002 Jul 20 by Robert Love. 1789 * 1790 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise. 1791 * 1792 * Note this is a helper function intended to be used by LSMs which 1793 * wish to use this logic. 1794 */ 1795int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin) 1796{ 1797 unsigned long free, allowed; 1798 1799 vm_acct_memory(pages); 1800 1801 /* 1802 * Sometimes we want to use more memory than we have 1803 */ 1804 if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS) 1805 return 0; 1806 1807 if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { 1808 unsigned long n; 1809 1810 free = global_page_state(NR_FILE_PAGES); 1811 free += nr_swap_pages; 1812 1813 /* 1814 * Any slabs which are created with the 1815 * SLAB_RECLAIM_ACCOUNT flag claim to have contents 1816 * which are reclaimable, under pressure. The dentry 1817 * cache and most inode caches should fall into this 1818 */ 1819 free += global_page_state(NR_SLAB_RECLAIMABLE); 1820 1821 /* 1822 * Leave the last 3% for root 1823 */ 1824 if (!cap_sys_admin) 1825 free -= free / 32; 1826 1827 if (free > pages) 1828 return 0; 1829 1830 /* 1831 * nr_free_pages() is very expensive on large systems, 1832 * only call if we're about to fail. 1833 */ 1834 n = nr_free_pages(); 1835 1836 /* 1837 * Leave reserved pages. The pages are not for anonymous pages. 1838 */ 1839 if (n <= totalreserve_pages) 1840 goto error; 1841 else 1842 n -= totalreserve_pages; 1843 1844 /* 1845 * Leave the last 3% for root 1846 */ 1847 if (!cap_sys_admin) 1848 n -= n / 32; 1849 free += n; 1850 1851 if (free > pages) 1852 return 0; 1853 1854 goto error; 1855 } 1856 1857 allowed = totalram_pages * sysctl_overcommit_ratio / 100; 1858 /* 1859 * Leave the last 3% for root 1860 */ 1861 if (!cap_sys_admin) 1862 allowed -= allowed / 32; 1863 allowed += total_swap_pages; 1864 1865 /* Don't let a single process grow too big: 1866 leave 3% of the size of this process for other processes */ 1867 if (mm) 1868 allowed -= mm->total_vm / 32; 1869 1870 if (percpu_counter_read_positive(&vm_committed_as) < allowed) 1871 return 0; 1872 1873error: 1874 vm_unacct_memory(pages); 1875 1876 return -ENOMEM; 1877} 1878 1879int in_gate_area_no_task(unsigned long addr) 1880{ 1881 return 0; 1882} 1883 1884int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) 1885{ 1886 BUG(); 1887 return 0; 1888} 1889EXPORT_SYMBOL(filemap_fault); 1890 1891/* 1892 * Access another process' address space. 1893 * - source/target buffer must be kernel space 1894 */ 1895int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write) 1896{ 1897 struct vm_area_struct *vma; 1898 struct mm_struct *mm; 1899 1900 if (addr + len < addr) 1901 return 0; 1902 1903 mm = get_task_mm(tsk); 1904 if (!mm) 1905 return 0; 1906 1907 down_read(&mm->mmap_sem); 1908 1909 /* the access must start within one of the target process's mappings */ 1910 vma = find_vma(mm, addr); 1911 if (vma) { 1912 /* don't overrun this mapping */ 1913 if (addr + len >= vma->vm_end) 1914 len = vma->vm_end - addr; 1915 1916 /* only read or write mappings where it is permitted */ 1917 if (write && vma->vm_flags & VM_MAYWRITE) 1918 len -= copy_to_user((void *) addr, buf, len); 1919 else if (!write && vma->vm_flags & VM_MAYREAD) 1920 len -= copy_from_user(buf, (void *) addr, len); 1921 else 1922 len = 0; 1923 } else { 1924 len = 0; 1925 } 1926 1927 up_read(&mm->mmap_sem); 1928 mmput(mm); 1929 return len; 1930} 1931