mm/nommu.c

   1 /*
   2  *  linux/mm/nommu.c
   3  *
   4  *  Replacement code for mm functions to support CPU's that don't
   5  *  have any form of memory management unit (thus no virtual memory).
   6  *
   7  *  See Documentation/nommu-mmap.txt
   8  *
   9  *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
  10  *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
  11  *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
  12  *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
  13  *  Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
  14  */
  15
  16 #include <linux/export.h>
  17 #include <linux/mm.h>
  18 #include <linux/mman.h>
  19 #include <linux/swap.h>
  20 #include <linux/file.h>
  21 #include <linux/highmem.h>
  22 #include <linux/pagemap.h>
  23 #include <linux/slab.h>
  24 #include <linux/vmalloc.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/backing-dev.h>
  27 #include <linux/mount.h>
  28 #include <linux/personality.h>
  29 #include <linux/security.h>
  30 #include <linux/syscalls.h>
  31 #include <linux/audit.h>
  32
  33 #include <asm/uaccess.h>
  34 #include <asm/tlb.h>
  35 #include <asm/tlbflush.h>
  36 #include <asm/mmu_context.h>
  37 #include "internal.h"
  38
  39 #if 0
  40 #define kenter(FMT, ...) \
  41         printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  42 #define kleave(FMT, ...) \
  43         printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  44 #define kdebug(FMT, ...) \
  45         printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
  46 #else
  47 #define kenter(FMT, ...) \
  48         no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  49 #define kleave(FMT, ...) \
  50         no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  51 #define kdebug(FMT, ...) \
  52         no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
  53 #endif
  54
  55 void *high_memory;
  56 struct page *mem_map;
  57 unsigned long max_mapnr;
  58 unsigned long num_physpages;
  59 unsigned long highest_memmap_pfn;
  60 struct percpu_counter vm_committed_as;
  61 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  62 int sysctl_overcommit_ratio = 50; /* default is 50% */
  63 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  64 int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
  65 int heap_stack_gap = 0;
  66
  67 atomic_long_t mmap_pages_allocated;
  68
  69 EXPORT_SYMBOL(mem_map);
  70 EXPORT_SYMBOL(num_physpages);
  71
  72 /* list of mapped, potentially shareable regions */
  73 static struct kmem_cache *vm_region_jar;
  74 struct rb_root nommu_region_tree = RB_ROOT;
  75 DECLARE_RWSEM(nommu_region_sem);
  76
  77 const struct vm_operations_struct generic_file_vm_ops = {
  78 };
  79
  80 /*
  81  * Return the total memory allocated for this pointer, not
  82  * just what the caller asked for.
  83  *
  84  * Doesn't have to be accurate, i.e. may have races.
  85  */
  86 unsigned int kobjsize(const void *objp)
  87 {
  88         struct page *page;
  89
  90         /*
  91          * If the object we have should not have ksize performed on it,
  92          * return size of 0
  93          */
  94         if (!objp || !virt_addr_valid(objp))
  95                 return 0;
  96
  97         page = virt_to_head_page(objp);
  98
  99         /*
 100          * If the allocator sets PageSlab, we know the pointer came from
 101          * kmalloc().
 102          */
 103         if (PageSlab(page))
 104                 return ksize(objp);
 105
 106         /*
 107          * If it's not a compound page, see if we have a matching VMA
 108          * region. This test is intentionally done in reverse order,
 109          * so if there's no VMA, we still fall through and hand back
 110          * PAGE_SIZE for 0-order pages.
 111          */
 112         if (!PageCompound(page)) {
 113                 struct vm_area_struct *vma;
 114
 115                 vma = find_vma(current->mm, (unsigned long)objp);
 116                 if (vma)
 117                         return vma->vm_end - vma->vm_start;
 118         }
 119
 120         /*
 121          * The ksize() function is only guaranteed to work for pointers
 122          * returned by kmalloc(). So handle arbitrary pointers here.
 123          */
 124         return PAGE_SIZE << compound_order(page);
 125 }
 126
 127 int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 128                      unsigned long start, int nr_pages, unsigned int foll_flags,
 129                      struct page **pages, struct vm_area_struct **vmas,
 130                      int *retry)
 131 {
 132         struct vm_area_struct *vma;
 133         unsigned long vm_flags;
 134         int i;
 135
 136         /* calculate required read or write permissions.
 137          * If FOLL_FORCE is set, we only require the "MAY" flags.
 138          */
 139         vm_flags  = (foll_flags & FOLL_WRITE) ?
 140                         (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 141         vm_flags &= (foll_flags & FOLL_FORCE) ?
 142                         (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 143
 144         for (i = 0; i < nr_pages; i++) {
 145                 vma = find_vma(mm, start);
 146                 if (!vma)
 147                         goto finish_or_fault;
 148
 149                 /* protect what we can, including chardevs */
 150                 if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
 151                     !(vm_flags & vma->vm_flags))
 152                         goto finish_or_fault;
 153
 154                 if (pages) {
 155                         pages[i] = virt_to_page(start);
 156                         if (pages[i])
 157                                 page_cache_get(pages[i]);
 158                 }
 159                 if (vmas)
 160                         vmas[i] = vma;
 161                 start = (start + PAGE_SIZE) & PAGE_MASK;
 162         }
 163
 164         return i;
 165
 166 finish_or_fault:
 167         return i ? : -EFAULT;
 168 }
 169
 170 /*
 171  * get a list of pages in an address range belonging to the specified process
 172  * and indicate the VMA that covers each page
 173  * - this is potentially dodgy as we may end incrementing the page count of a
 174  *   slab page or a secondary page from a compound page
 175  * - don't permit access to VMAs that don't support it, such as I/O mappings
 176  */
 177 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 178         unsigned long start, int nr_pages, int write, int force,
 179         struct page **pages, struct vm_area_struct **vmas)
 180 {
 181         int flags = 0;
 182
 183         if (write)
 184                 flags |= FOLL_WRITE;
 185         if (force)
 186                 flags |= FOLL_FORCE;
 187
 188         return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
 189                                 NULL);
 190 }
 191 EXPORT_SYMBOL(get_user_pages);
 192
 193 /**
 194  * follow_pfn - look up PFN at a user virtual address
 195  * @vma: memory mapping
 196  * @address: user virtual address
 197  * @pfn: location to store found PFN
 198  *
 199  * Only IO mappings and raw PFN mappings are allowed.
 200  *
 201  * Returns zero and the pfn at @pfn on success, -ve otherwise.
 202  */
 203 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 204         unsigned long *pfn)
 205 {
 206         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 207                 return -EINVAL;
 208
 209         *pfn = address >> PAGE_SHIFT;
 210         return 0;
 211 }
 212 EXPORT_SYMBOL(follow_pfn);
 213
 214 DEFINE_RWLOCK(vmlist_lock);
 215 struct vm_struct *vmlist;
 216
 217 void vfree(const void *addr)
 218 {
 219         kfree(addr);
 220 }
 221 EXPORT_SYMBOL(vfree);
 222
 223 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 224 {
 225         /*
 226          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 227          * returns only a logical address.
 228          */
 229         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 230 }
 231 EXPORT_SYMBOL(__vmalloc);
 232
 233 void *vmalloc_user(unsigned long size)
 234 {
 235         void *ret;
 236
 237         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 238                         PAGE_KERNEL);
 239         if (ret) {
 240                 struct vm_area_struct *vma;
 241
 242                 down_write(&current->mm->mmap_sem);
 243                 vma = find_vma(current->mm, (unsigned long)ret);
 244                 if (vma)
 245                         vma->vm_flags |= VM_USERMAP;
 246                 up_write(&current->mm->mmap_sem);
 247         }
 248
 249         return ret;
 250 }
 251 EXPORT_SYMBOL(vmalloc_user);
 252
 253 struct page *vmalloc_to_page(const void *addr)
 254 {
 255         return virt_to_page(addr);
 256 }
 257 EXPORT_SYMBOL(vmalloc_to_page);
 258
 259 unsigned long vmalloc_to_pfn(const void *addr)
 260 {
 261         return page_to_pfn(virt_to_page(addr));
 262 }
 263 EXPORT_SYMBOL(vmalloc_to_pfn);
 264
 265 long vread(char *buf, char *addr, unsigned long count)
 266 {
 267         memcpy(buf, addr, count);
 268         return count;
 269 }
 270
 271 long vwrite(char *buf, char *addr, unsigned long count)
 272 {
 273         /* Don't allow overflow */
 274         if ((unsigned long) addr + count < count)
 275                 count = -(unsigned long) addr;
 276
 277         memcpy(addr, buf, count);
 278         return(count);
 279 }
 280
 281 /*
 282  *      vmalloc  -  allocate virtually continguos memory
 283  *
 284  *      @size:          allocation size
 285  *
 286  *      Allocate enough pages to cover @size from the page level
 287  *      allocator and map them into continguos kernel virtual space.
 288  *
 289  *      For tight control over page level allocator and protection flags
 290  *      use __vmalloc() instead.
 291  */
 292 void *vmalloc(unsigned long size)
 293 {
 294        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 295 }
 296 EXPORT_SYMBOL(vmalloc);
 297
 298 /*
 299  *      vzalloc - allocate virtually continguos memory with zero fill
 300  *
 301  *      @size:          allocation size
 302  *
 303  *      Allocate enough pages to cover @size from the page level
 304  *      allocator and map them into continguos kernel virtual space.
 305  *      The memory allocated is set to zero.
 306  *
 307  *      For tight control over page level allocator and protection flags
 308  *      use __vmalloc() instead.
 309  */
 310 void *vzalloc(unsigned long size)
 311 {
 312         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 313                         PAGE_KERNEL);
 314 }
 315 EXPORT_SYMBOL(vzalloc);
 316
 317 /**
 318  * vmalloc_node - allocate memory on a specific node
 319  * @size:       allocation size
 320  * @node:       numa node
 321  *
 322  * Allocate enough pages to cover @size from the page level
 323  * allocator and map them into contiguous kernel virtual space.
 324  *
 325  * For tight control over page level allocator and protection flags
 326  * use __vmalloc() instead.
 327  */
 328 void *vmalloc_node(unsigned long size, int node)
 329 {
 330         return vmalloc(size);
 331 }
 332 EXPORT_SYMBOL(vmalloc_node);
 333
 334 /**
 335  * vzalloc_node - allocate memory on a specific node with zero fill
 336  * @size:       allocation size
 337  * @node:       numa node
 338  *
 339  * Allocate enough pages to cover @size from the page level
 340  * allocator and map them into contiguous kernel virtual space.
 341  * The memory allocated is set to zero.
 342  *
 343  * For tight control over page level allocator and protection flags
 344  * use __vmalloc() instead.
 345  */
 346 void *vzalloc_node(unsigned long size, int node)
 347 {
 348         return vzalloc(size);
 349 }
 350 EXPORT_SYMBOL(vzalloc_node);
 351
 352 #ifndef PAGE_KERNEL_EXEC
 353 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 354 #endif
 355
 356 /**
 357  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 358  *      @size:          allocation size
 359  *
 360  *      Kernel-internal function to allocate enough pages to cover @size
 361  *      the page level allocator and map them into contiguous and
 362  *      executable kernel virtual space.
 363  *
 364  *      For tight control over page level allocator and protection flags
 365  *      use __vmalloc() instead.
 366  */
 367
 368 void *vmalloc_exec(unsigned long size)
 369 {
 370         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 371 }
 372
 373 /**
 374  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 375  *      @size:          allocation size
 376  *
 377  *      Allocate enough 32bit PA addressable pages to cover @size from the
 378  *      page level allocator and map them into continguos kernel virtual space.
 379  */
 380 void *vmalloc_32(unsigned long size)
 381 {
 382         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 383 }
 384 EXPORT_SYMBOL(vmalloc_32);
 385
 386 /**
 387  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 388  *      @size:          allocation size
 389  *
 390  * The resulting memory area is 32bit addressable and zeroed so it can be
 391  * mapped to userspace without leaking data.
 392  *
 393  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 394  * remap_vmalloc_range() are permissible.
 395  */
 396 void *vmalloc_32_user(unsigned long size)
 397 {
 398         /*
 399          * We'll have to sort out the ZONE_DMA bits for 64-bit,
 400          * but for now this can simply use vmalloc_user() directly.
 401          */
 402         return vmalloc_user(size);
 403 }
 404 EXPORT_SYMBOL(vmalloc_32_user);
 405
 406 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 407 {
 408         BUG();
 409         return NULL;
 410 }
 411 EXPORT_SYMBOL(vmap);
 412
 413 void vunmap(const void *addr)
 414 {
 415         BUG();
 416 }
 417 EXPORT_SYMBOL(vunmap);
 418
 419 void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
 420 {
 421         BUG();
 422         return NULL;
 423 }
 424 EXPORT_SYMBOL(vm_map_ram);
 425
 426 void vm_unmap_ram(const void *mem, unsigned int count)
 427 {
 428         BUG();
 429 }
 430 EXPORT_SYMBOL(vm_unmap_ram);
 431
 432 void vm_unmap_aliases(void)
 433 {
 434 }
 435 EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 436
 437 /*
 438  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 439  * have one.
 440  */
 441 void  __attribute__((weak)) vmalloc_sync_all(void)
 442 {
 443 }
 444
 445 /**
 446  *      alloc_vm_area - allocate a range of kernel address space
 447  *      @size:          size of the area
 448  *
 449  *      Returns:        NULL on failure, vm_struct on success
 450  *
 451  *      This function reserves a range of kernel address space, and
 452  *      allocates pagetables to map that range.  No actual mappings
 453  *      are created.  If the kernel address space is not shared
 454  *      between processes, it syncs the pagetable across all
 455  *      processes.
 456  */
 457 struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
 458 {
 459         BUG();
 460         return NULL;
 461 }
 462 EXPORT_SYMBOL_GPL(alloc_vm_area);
 463
 464 void free_vm_area(struct vm_struct *area)
 465 {
 466         BUG();
 467 }
 468 EXPORT_SYMBOL_GPL(free_vm_area);
 469
 470 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 471                    struct page *page)
 472 {
 473         return -EINVAL;
 474 }
 475 EXPORT_SYMBOL(vm_insert_page);
 476
 477 /*
 478  *  sys_brk() for the most part doesn't need the global kernel
 479  *  lock, except when an application is doing something nasty
 480  *  like trying to un-brk an area that has already been mapped
 481  *  to a regular file.  in this case, the unmapping will need
 482  *  to invoke file system routines that need the global lock.
 483  */
 484 SYSCALL_DEFINE1(brk, unsigned long, brk)
 485 {
 486         struct mm_struct *mm = current->mm;
 487
 488         if (brk < mm->start_brk || brk > mm->context.end_brk)
 489                 return mm->brk;
 490
 491         if (mm->brk == brk)
 492                 return mm->brk;
 493
 494         /*
 495          * Always allow shrinking brk
 496          */
 497         if (brk <= mm->brk) {
 498                 mm->brk = brk;
 499                 return brk;
 500         }
 501
 502         /*
 503          * Ok, looks good - let it rip.
 504          */
 505         flush_icache_range(mm->brk, brk);
 506         return mm->brk = brk;
 507 }
 508
 509 /*
 510  * initialise the VMA and region record slabs
 511  */
 512 void __init mmap_init(void)
 513 {
 514         int ret;
 515
 516         ret = percpu_counter_init(&vm_committed_as, 0);
 517         VM_BUG_ON(ret);
 518         vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
 519 }
 520
 521 /*
 522  * validate the region tree
 523  * - the caller must hold the region lock
 524  */
 525 #ifdef CONFIG_DEBUG_NOMMU_REGIONS
 526 static noinline void validate_nommu_regions(void)
 527 {
 528         struct vm_region *region, *last;
 529         struct rb_node *p, *lastp;
 530
 531         lastp = rb_first(&nommu_region_tree);
 532         if (!lastp)
 533                 return;
 534
 535         last = rb_entry(lastp, struct vm_region, vm_rb);
 536         BUG_ON(unlikely(last->vm_end <= last->vm_start));
 537         BUG_ON(unlikely(last->vm_top < last->vm_end));
 538
 539         while ((p = rb_next(lastp))) {
 540                 region = rb_entry(p, struct vm_region, vm_rb);
 541                 last = rb_entry(lastp, struct vm_region, vm_rb);
 542
 543                 BUG_ON(unlikely(region->vm_end <= region->vm_start));
 544                 BUG_ON(unlikely(region->vm_top < region->vm_end));
 545                 BUG_ON(unlikely(region->vm_start < last->vm_top));
 546
 547                 lastp = p;
 548         }
 549 }
 550 #else
 551 static void validate_nommu_regions(void)
 552 {
 553 }
 554 #endif
 555
 556 /*
 557  * add a region into the global tree
 558  */
 559 static void add_nommu_region(struct vm_region *region)
 560 {
 561         struct vm_region *pregion;
 562         struct rb_node **p, *parent;
 563
 564         validate_nommu_regions();
 565
 566         parent = NULL;
 567         p = &nommu_region_tree.rb_node;
 568         while (*p) {
 569                 parent = *p;
 570                 pregion = rb_entry(parent, struct vm_region, vm_rb);
 571                 if (region->vm_start < pregion->vm_start)
 572                         p = &(*p)->rb_left;
 573                 else if (region->vm_start > pregion->vm_start)
 574                         p = &(*p)->rb_right;
 575                 else if (pregion == region)
 576                         return;
 577                 else
 578                         BUG();
 579         }
 580
 581         rb_link_node(&region->vm_rb, parent, p);
 582         rb_insert_color(&region->vm_rb, &nommu_region_tree);
 583
 584         validate_nommu_regions();
 585 }
 586
 587 /*
 588  * delete a region from the global tree
 589  */
 590 static void delete_nommu_region(struct vm_region *region)
 591 {
 592         BUG_ON(!nommu_region_tree.rb_node);
 593
 594         validate_nommu_regions();
 595         rb_erase(&region->vm_rb, &nommu_region_tree);
 596         validate_nommu_regions();
 597 }
 598
 599 /*
 600  * free a contiguous series of pages
 601  */
 602 static void free_page_series(unsigned long from, unsigned long to)
 603 {
 604         for (; from < to; from += PAGE_SIZE) {
 605                 struct page *page = virt_to_page(from);
 606
 607                 kdebug("- free %lx", from);
 608                 atomic_long_dec(&mmap_pages_allocated);
 609                 if (page_count(page) != 1)
 610                         kdebug("free page %p: refcount not one: %d",
 611                                page, page_count(page));
 612                 put_page(page);
 613         }
 614 }
 615
 616 /*
 617  * release a reference to a region
 618  * - the caller must hold the region semaphore for writing, which this releases
 619  * - the region may not have been added to the tree yet, in which case vm_top
 620  *   will equal vm_start
 621  */
 622 static void __put_nommu_region(struct vm_region *region)
 623         __releases(nommu_region_sem)
 624 {
 625         kenter("%p{%d}", region, region->vm_usage);
 626
 627         BUG_ON(!nommu_region_tree.rb_node);
 628
 629         if (--region->vm_usage == 0) {
 630                 if (region->vm_top > region->vm_start)
 631                         delete_nommu_region(region);
 632                 up_write(&nommu_region_sem);
 633
 634                 if (region->vm_file)
 635                         fput(region->vm_file);
 636
 637                 /* IO memory and memory shared directly out of the pagecache
 638                  * from ramfs/tmpfs mustn't be released here */
 639                 if (region->vm_flags & VM_MAPPED_COPY) {
 640                         kdebug("free series");
 641                         free_page_series(region->vm_start, region->vm_top);
 642                 }
 643                 kmem_cache_free(vm_region_jar, region);
 644         } else {
 645                 up_write(&nommu_region_sem);
 646         }
 647 }
 648
 649 /*
 650  * release a reference to a region
 651  */
 652 static void put_nommu_region(struct vm_region *region)
 653 {
 654         down_write(&nommu_region_sem);
 655         __put_nommu_region(region);
 656 }
 657
 658 /*
 659  * update protection on a vma
 660  */
 661 static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
 662 {
 663 #ifdef CONFIG_MPU
 664         struct mm_struct *mm = vma->vm_mm;
 665         long start = vma->vm_start & PAGE_MASK;
 666         while (start < vma->vm_end) {
 667                 protect_page(mm, start, flags);
 668                 start += PAGE_SIZE;
 669         }
 670         update_protections(mm);
 671 #endif
 672 }
 673
 674 /*
 675  * add a VMA into a process's mm_struct in the appropriate place in the list
 676  * and tree and add to the address space's page tree also if not an anonymous
 677  * page
 678  * - should be called with mm->mmap_sem held writelocked
 679  */
 680 static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 681 {
 682         struct vm_area_struct *pvma, *prev;
 683         struct address_space *mapping;
 684         struct rb_node **p, *parent, *rb_prev;
 685
 686         kenter(",%p", vma);
 687
 688         BUG_ON(!vma->vm_region);
 689
 690         mm->map_count++;
 691         vma->vm_mm = mm;
 692
 693         protect_vma(vma, vma->vm_flags);
 694
 695         /* add the VMA to the mapping */
 696         if (vma->vm_file) {
 697                 mapping = vma->vm_file->f_mapping;
 698
 699                 mutex_lock(&mapping->i_mmap_mutex);
 700                 flush_dcache_mmap_lock(mapping);
 701                 vma_interval_tree_insert(vma, &mapping->i_mmap);
 702                 flush_dcache_mmap_unlock(mapping);
 703                 mutex_unlock(&mapping->i_mmap_mutex);
 704         }
 705
 706         /* add the VMA to the tree */
 707         parent = rb_prev = NULL;
 708         p = &mm->mm_rb.rb_node;
 709         while (*p) {
 710                 parent = *p;
 711                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 712
 713                 /* sort by: start addr, end addr, VMA struct addr in that order
 714                  * (the latter is necessary as we may get identical VMAs) */
 715                 if (vma->vm_start < pvma->vm_start)
 716                         p = &(*p)->rb_left;
 717                 else if (vma->vm_start > pvma->vm_start) {
 718                         rb_prev = parent;
 719                         p = &(*p)->rb_right;
 720                 } else if (vma->vm_end < pvma->vm_end)
 721                         p = &(*p)->rb_left;
 722                 else if (vma->vm_end > pvma->vm_end) {
 723                         rb_prev = parent;
 724                         p = &(*p)->rb_right;
 725                 } else if (vma < pvma)
 726                         p = &(*p)->rb_left;
 727                 else if (vma > pvma) {
 728                         rb_prev = parent;
 729                         p = &(*p)->rb_right;
 730                 } else
 731                         BUG();
 732         }
 733
 734         rb_link_node(&vma->vm_rb, parent, p);
 735         rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 736
 737         /* add VMA to the VMA list also */
 738         prev = NULL;
 739         if (rb_prev)
 740                 prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 741
 742         __vma_link_list(mm, vma, prev, parent);
 743 }
 744
 745 /*
 746  * delete a VMA from its owning mm_struct and address space
 747  */
 748 static void delete_vma_from_mm(struct vm_area_struct *vma)
 749 {
 750         struct address_space *mapping;
 751         struct mm_struct *mm = vma->vm_mm;
 752
 753         kenter("%p", vma);
 754
 755         protect_vma(vma, 0);
 756
 757         mm->map_count--;
 758         if (mm->mmap_cache == vma)
 759                 mm->mmap_cache = NULL;
 760
 761         /* remove the VMA from the mapping */
 762         if (vma->vm_file) {
 763                 mapping = vma->vm_file->f_mapping;
 764
 765                 mutex_lock(&mapping->i_mmap_mutex);
 766                 flush_dcache_mmap_lock(mapping);
 767                 vma_interval_tree_remove(vma, &mapping->i_mmap);
 768                 flush_dcache_mmap_unlock(mapping);
 769                 mutex_unlock(&mapping->i_mmap_mutex);
 770         }
 771
 772         /* remove from the MM's tree and list */
 773         rb_erase(&vma->vm_rb, &mm->mm_rb);
 774
 775         if (vma->vm_prev)
 776                 vma->vm_prev->vm_next = vma->vm_next;
 777         else
 778                 mm->mmap = vma->vm_next;
 779
 780         if (vma->vm_next)
 781                 vma->vm_next->vm_prev = vma->vm_prev;
 782 }
 783
 784 /*
 785  * destroy a VMA record
 786  */
 787 static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 788 {
 789         kenter("%p", vma);
 790         if (vma->vm_ops && vma->vm_ops->close)
 791                 vma->vm_ops->close(vma);
 792         if (vma->vm_file)
 793                 fput(vma->vm_file);
 794         put_nommu_region(vma->vm_region);
 795         kmem_cache_free(vm_area_cachep, vma);
 796 }
 797
 798 /*
 799  * look up the first VMA in which addr resides, NULL if none
 800  * - should be called with mm->mmap_sem at least held readlocked
 801  */
 802 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 803 {
 804         struct vm_area_struct *vma;
 805
 806         /* check the cache first */
 807         vma = mm->mmap_cache;
 808         if (vma && vma->vm_start <= addr && vma->vm_end > addr)
 809                 return vma;
 810
 811         /* trawl the list (there may be multiple mappings in which addr
 812          * resides) */
 813         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 814                 if (vma->vm_start > addr)
 815                         return NULL;
 816                 if (vma->vm_end > addr) {
 817                         mm->mmap_cache = vma;
 818                         return vma;
 819                 }
 820         }
 821
 822         return NULL;
 823 }
 824 EXPORT_SYMBOL(find_vma);
 825
 826 /*
 827  * find a VMA
 828  * - we don't extend stack VMAs under NOMMU conditions
 829  */
 830 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 831 {
 832         return find_vma(mm, addr);
 833 }
 834
 835 /*
 836  * expand a stack to a given address
 837  * - not supported under NOMMU conditions
 838  */
 839 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 840 {
 841         return -ENOMEM;
 842 }
 843
 844 /*
 845  * look up the first VMA exactly that exactly matches addr
 846  * - should be called with mm->mmap_sem at least held readlocked
 847  */
 848 static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 849                                              unsigned long addr,
 850                                              unsigned long len)
 851 {
 852         struct vm_area_struct *vma;
 853         unsigned long end = addr + len;
 854
 855         /* check the cache first */
 856         vma = mm->mmap_cache;
 857         if (vma && vma->vm_start == addr && vma->vm_end == end)
 858                 return vma;
 859
 860         /* trawl the list (there may be multiple mappings in which addr
 861          * resides) */
 862         for (vma = mm->mmap; vma; vma = vma->vm_next) {
 863                 if (vma->vm_start < addr)
 864                         continue;
 865                 if (vma->vm_start > addr)
 866                         return NULL;
 867                 if (vma->vm_end == end) {
 868                         mm->mmap_cache = vma;
 869                         return vma;
 870                 }
 871         }
 872
 873         return NULL;
 874 }
 875
 876 /*
 877  * determine whether a mapping should be permitted and, if so, what sort of
 878  * mapping we're capable of supporting
 879  */
 880 static int validate_mmap_request(struct file *file,
 881                                  unsigned long addr,
 882                                  unsigned long len,
 883                                  unsigned long prot,
 884                                  unsigned long flags,
 885                                  unsigned long pgoff,
 886                                  unsigned long *_capabilities)
 887 {
 888         unsigned long capabilities, rlen;
 889         int ret;
 890
 891         /* do the simple checks first */
 892         if (flags & MAP_FIXED) {
 893                 printk(KERN_DEBUG
 894                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 895                        current->pid);
 896                 return -EINVAL;
 897         }
 898
 899         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 900             (flags & MAP_TYPE) != MAP_SHARED)
 901                 return -EINVAL;
 902
 903         if (!len)
 904                 return -EINVAL;
 905
 906         /* Careful about overflows.. */
 907         rlen = PAGE_ALIGN(len);
 908         if (!rlen || rlen > TASK_SIZE)
 909                 return -ENOMEM;
 910
 911         /* offset overflow? */
 912         if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
 913                 return -EOVERFLOW;
 914
 915         if (file) {
 916                 /* validate file mapping requests */
 917                 struct address_space *mapping;
 918
 919                 /* files must support mmap */
 920                 if (!file->f_op || !file->f_op->mmap)
 921                         return -ENODEV;
 922
 923                 /* work out if what we've got could possibly be shared
 924                  * - we support chardevs that provide their own "memory"
 925                  * - we support files/blockdevs that are memory backed
 926                  */
 927                 mapping = file->f_mapping;
 928                 if (!mapping)
 929                         mapping = file->f_path.dentry->d_inode->i_mapping;
 930
 931                 capabilities = 0;
 932                 if (mapping && mapping->backing_dev_info)
 933                         capabilities = mapping->backing_dev_info->capabilities;
 934
 935                 if (!capabilities) {
 936                         /* no explicit capabilities set, so assume some
 937                          * defaults */
 938                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
 939                         case S_IFREG:
 940                         case S_IFBLK:
 941                                 capabilities = BDI_CAP_MAP_COPY;
 942                                 break;
 943
 944                         case S_IFCHR:
 945                                 capabilities =
 946                                         BDI_CAP_MAP_DIRECT |
 947                                         BDI_CAP_READ_MAP |
 948                                         BDI_CAP_WRITE_MAP;
 949                                 break;
 950
 951                         default:
 952                                 return -EINVAL;
 953                         }
 954                 }
 955
 956                 /* eliminate any capabilities that we can't support on this
 957                  * device */
 958                 if (!file->f_op->get_unmapped_area)
 959                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 960                 if (!file->f_op->read)
 961                         capabilities &= ~BDI_CAP_MAP_COPY;
 962
 963                 /* The file shall have been opened with read permission. */
 964                 if (!(file->f_mode & FMODE_READ))
 965                         return -EACCES;
 966
 967                 if (flags & MAP_SHARED) {
 968                         /* do checks for writing, appending and locking */
 969                         if ((prot & PROT_WRITE) &&
 970                             !(file->f_mode & FMODE_WRITE))
 971                                 return -EACCES;
 972
 973                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
 974                             (file->f_mode & FMODE_WRITE))
 975                                 return -EACCES;
 976
 977                         if (locks_verify_locked(file->f_path.dentry->d_inode))
 978                                 return -EAGAIN;
 979
 980                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 981                                 return -ENODEV;
 982
 983                         /* we mustn't privatise shared mappings */
 984                         capabilities &= ~BDI_CAP_MAP_COPY;
 985                 }
 986                 else {
 987                         /* we're going to read the file into private memory we
 988                          * allocate */
 989                         if (!(capabilities & BDI_CAP_MAP_COPY))
 990                                 return -ENODEV;
 991
 992                         /* we don't permit a private writable mapping to be
 993                          * shared with the backing device */
 994                         if (prot & PROT_WRITE)
 995                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 996                 }
 997
 998                 if (capabilities & BDI_CAP_MAP_DIRECT) {
 999                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
1000                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1001                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
1002                             ) {
1003                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1004                                 if (flags & MAP_SHARED) {
1005                                         printk(KERN_WARNING
1006                                                "MAP_SHARED not completely supported on !MMU\n");
1007                                         return -EINVAL;
1008                                 }
1009                         }
1010                 }
1011
1012                 /* handle executable mappings and implied executable
1013                  * mappings */
1014                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1015                         if (prot & PROT_EXEC)
1016                                 return -EPERM;
1017                 }
1018                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1019                         /* handle implication of PROT_EXEC by PROT_READ */
1020                         if (current->personality & READ_IMPLIES_EXEC) {
1021                                 if (capabilities & BDI_CAP_EXEC_MAP)
1022                                         prot |= PROT_EXEC;
1023                         }
1024                 }
1025                 else if ((prot & PROT_READ) &&
1026                          (prot & PROT_EXEC) &&
1027                          !(capabilities & BDI_CAP_EXEC_MAP)
1028                          ) {
1029                         /* backing file is not executable, try to copy */
1030                         capabilities &= ~BDI_CAP_MAP_DIRECT;
1031                 }
1032         }
1033         else {
1034                 /* anonymous mappings are always memory backed and can be
1035                  * privately mapped
1036                  */
1037                 capabilities = BDI_CAP_MAP_COPY;
1038
1039                 /* handle PROT_EXEC implication by PROT_READ */
1040                 if ((prot & PROT_READ) &&
1041                     (current->personality & READ_IMPLIES_EXEC))
1042                         prot |= PROT_EXEC;
1043         }
1044
1045         /* allow the security API to have its say */
1046         ret = security_mmap_addr(addr);
1047         if (ret < 0)
1048                 return ret;
1049
1050         /* looks okay */
1051         *_capabilities = capabilities;
1052         return 0;
1053 }
1054
1055 /*
1056  * we've determined that we can make the mapping, now translate what we
1057  * now know into VMA flags
1058  */
1059 static unsigned long determine_vm_flags(struct file *file,
1060                                         unsigned long prot,
1061                                         unsigned long flags,
1062                                         unsigned long capabilities)
1063 {
1064         unsigned long vm_flags;
1065
1066         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1067         /* vm_flags |= mm->def_flags; */
1068
1069         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1070                 /* attempt to share read-only copies of mapped file chunks */
1071                 vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1072                 if (file && !(prot & PROT_WRITE))
1073                         vm_flags |= VM_MAYSHARE;
1074         } else {
1075                 /* overlay a shareable mapping on the backing device or inode
1076                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1077                  * romfs/cramfs */
1078                 vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1079                 if (flags & MAP_SHARED)
1080                         vm_flags |= VM_SHARED;
1081         }
1082
1083         /* refuse to let anyone share private mappings with this process if
1084          * it's being traced - otherwise breakpoints set in it may interfere
1085          * with another untraced process
1086          */
1087         if ((flags & MAP_PRIVATE) && current->ptrace)
1088                 vm_flags &= ~VM_MAYSHARE;
1089
1090         return vm_flags;
1091 }
1092
1093 /*
1094  * set up a shared mapping on a file (the driver or filesystem provides and
1095  * pins the storage)
1096  */
1097 static int do_mmap_shared_file(struct vm_area_struct *vma)
1098 {
1099         int ret;
1100
1101         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1102         if (ret == 0) {
1103                 vma->vm_region->vm_top = vma->vm_region->vm_end;
1104                 return 0;
1105         }
1106         if (ret != -ENOSYS)
1107                 return ret;
1108
1109         /* getting -ENOSYS indicates that direct mmap isn't possible (as
1110          * opposed to tried but failed) so we can only give a suitable error as
1111          * it's not possible to make a private copy if MAP_SHARED was given */
1112         return -ENODEV;
1113 }
1114
1115 /*
1116  * set up a private mapping or an anonymous shared mapping
1117  */
1118 static int do_mmap_private(struct vm_area_struct *vma,
1119                            struct vm_region *region,
1120                            unsigned long len,
1121                            unsigned long capabilities)
1122 {
1123         struct page *pages;
1124         unsigned long total, point, n;
1125         void *base;
1126         int ret, order;
1127
1128         /* invoke the file's mapping function so that it can keep track of
1129          * shared mappings on devices or memory
1130          * - VM_MAYSHARE will be set if it may attempt to share
1131          */
1132         if (capabilities & BDI_CAP_MAP_DIRECT) {
1133                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1134                 if (ret == 0) {
1135                         /* shouldn't return success if we're not sharing */
1136                         BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1137                         vma->vm_region->vm_top = vma->vm_region->vm_end;
1138                         return 0;
1139                 }
1140                 if (ret != -ENOSYS)
1141                         return ret;
1142
1143                 /* getting an ENOSYS error indicates that direct mmap isn't
1144                  * possible (as opposed to tried but failed) so we'll try to
1145                  * make a private copy of the data and map that instead */
1146         }
1147
1148
1149         /* allocate some memory to hold the mapping
1150          * - note that this may not return a page-aligned address if the object
1151          *   we're allocating is smaller than a page
1152          */
1153         order = get_order(len);
1154         kdebug("alloc order %d for %lx", order, len);
1155
1156         pages = alloc_pages(GFP_KERNEL, order);
1157         if (!pages)
1158                 goto enomem;
1159
1160         total = 1 << order;
1161         atomic_long_add(total, &mmap_pages_allocated);
1162
1163         point = len >> PAGE_SHIFT;
1164
1165         /* we allocated a power-of-2 sized page set, so we may want to trim off
1166          * the excess */
1167         if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1168                 while (total > point) {
1169                         order = ilog2(total - point);
1170                         n = 1 << order;
1171                         kdebug("shave %lu/%lu @%lu", n, total - point, total);
1172                         atomic_long_sub(n, &mmap_pages_allocated);
1173                         total -= n;
1174                         set_page_refcounted(pages + total);
1175                         __free_pages(pages + total, order);
1176                 }
1177         }
1178
1179         for (point = 1; point < total; point++)
1180                 set_page_refcounted(&pages[point]);
1181
1182         base = page_address(pages);
1183         region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1184         region->vm_start = (unsigned long) base;
1185         region->vm_end   = region->vm_start + len;
1186         region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1187
1188         vma->vm_start = region->vm_start;
1189         vma->vm_end   = region->vm_start + len;
1190
1191         if (vma->vm_file) {
1192                 /* read the contents of a file into the copy */
1193                 mm_segment_t old_fs;
1194                 loff_t fpos;
1195
1196                 fpos = vma->vm_pgoff;
1197                 fpos <<= PAGE_SHIFT;
1198
1199                 old_fs = get_fs();
1200                 set_fs(KERNEL_DS);
1201                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1202                 set_fs(old_fs);
1203
1204                 if (ret < 0)
1205                         goto error_free;
1206
1207                 /* clear the last little bit */
1208                 if (ret < len)
1209                         memset(base + ret, 0, len - ret);
1210
1211         }
1212
1213         return 0;
1214
1215 error_free:
1216         free_page_series(region->vm_start, region->vm_top);
1217         region->vm_start = vma->vm_start = 0;
1218         region->vm_end   = vma->vm_end = 0;
1219         region->vm_top   = 0;
1220         return ret;
1221
1222 enomem:
1223         printk("Allocation of length %lu from process %d (%s) failed\n",
1224                len, current->pid, current->comm);
1225         show_free_areas(0);
1226         return -ENOMEM;
1227 }
1228
1229 /*
1230  * handle mapping creation for uClinux
1231  */
1232 unsigned long do_mmap_pgoff(struct file *file,
1233                             unsigned long addr,
1234                             unsigned long len,
1235                             unsigned long prot,
1236                             unsigned long flags,
1237                             unsigned long pgoff)
1238 {
1239         struct vm_area_struct *vma;
1240         struct vm_region *region;
1241         struct rb_node *rb;
1242         unsigned long capabilities, vm_flags, result;
1243         int ret;
1244
1245         kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1246
1247         /* decide whether we should attempt the mapping, and if so what sort of
1248          * mapping */
1249         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1250                                     &capabilities);
1251         if (ret < 0) {
1252                 kleave(" = %d [val]", ret);
1253                 return ret;
1254         }
1255
1256         /* we ignore the address hint */
1257         addr = 0;
1258         len = PAGE_ALIGN(len);
1259
1260         /* we've determined that we can make the mapping, now translate what we
1261          * now know into VMA flags */
1262         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1263
1264         /* we're going to need to record the mapping */
1265         region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1266         if (!region)
1267                 goto error_getting_region;
1268
1269         vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1270         if (!vma)
1271                 goto error_getting_vma;
1272
1273         region->vm_usage = 1;
1274         region->vm_flags = vm_flags;
1275         region->vm_pgoff = pgoff;
1276
1277         INIT_LIST_HEAD(&vma->anon_vma_chain);
1278         vma->vm_flags = vm_flags;
1279         vma->vm_pgoff = pgoff;
1280
1281         if (file) {
1282                 region->vm_file = get_file(file);
1283                 vma->vm_file = get_file(file);
1284         }
1285
1286         down_write(&nommu_region_sem);
1287
1288         /* if we want to share, we need to check for regions created by other
1289          * mmap() calls that overlap with our proposed mapping
1290          * - we can only share with a superset match on most regular files
1291          * - shared mappings on character devices and memory backed files are
1292          *   permitted to overlap inexactly as far as we are concerned for in
1293          *   these cases, sharing is handled in the driver or filesystem rather
1294          *   than here
1295          */
1296         if (vm_flags & VM_MAYSHARE) {
1297                 struct vm_region *pregion;
1298                 unsigned long pglen, rpglen, pgend, rpgend, start;
1299
1300                 pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1301                 pgend = pgoff + pglen;
1302
1303                 for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1304                         pregion = rb_entry(rb, struct vm_region, vm_rb);
1305
1306                         if (!(pregion->vm_flags & VM_MAYSHARE))
1307                                 continue;
1308
1309                         /* search for overlapping mappings on the same file */
1310                         if (pregion->vm_file->f_path.dentry->d_inode !=
1311                             file->f_path.dentry->d_inode)
1312                                 continue;
1313
1314                         if (pregion->vm_pgoff >= pgend)
1315                                 continue;
1316
1317                         rpglen = pregion->vm_end - pregion->vm_start;
1318                         rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1319                         rpgend = pregion->vm_pgoff + rpglen;
1320                         if (pgoff >= rpgend)
1321                                 continue;
1322
1323                         /* handle inexactly overlapping matches between
1324                          * mappings */
1325                         if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1326                             !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1327                                 /* new mapping is not a subset of the region */
1328                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
1329                                         goto sharing_violation;
1330                                 continue;
1331                         }
1332
1333                         /* we've found a region we can share */
1334                         pregion->vm_usage++;
1335                         vma->vm_region = pregion;
1336                         start = pregion->vm_start;
1337                         start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1338                         vma->vm_start = start;
1339                         vma->vm_end = start + len;
1340
1341                         if (pregion->vm_flags & VM_MAPPED_COPY) {
1342                                 kdebug("share copy");
1343                                 vma->vm_flags |= VM_MAPPED_COPY;
1344                         } else {
1345                                 kdebug("share mmap");
1346                                 ret = do_mmap_shared_file(vma);
1347                                 if (ret < 0) {
1348                                         vma->vm_region = NULL;
1349                                         vma->vm_start = 0;
1350                                         vma->vm_end = 0;
1351                                         pregion->vm_usage--;
1352                                         pregion = NULL;
1353                                         goto error_just_free;
1354                                 }
1355                         }
1356                         fput(region->vm_file);
1357                         kmem_cache_free(vm_region_jar, region);
1358                         region = pregion;
1359                         result = start;
1360                         goto share;
1361                 }
1362
1363                 /* obtain the address at which to make a shared mapping
1364                  * - this is the hook for quasi-memory character devices to
1365                  *   tell us the location of a shared mapping
1366                  */
1367                 if (capabilities & BDI_CAP_MAP_DIRECT) {
1368                         addr = file->f_op->get_unmapped_area(file, addr, len,
1369                                                              pgoff, flags);
1370                         if (IS_ERR_VALUE(addr)) {
1371                                 ret = addr;
1372                                 if (ret != -ENOSYS)
1373                                         goto error_just_free;
1374
1375                                 /* the driver refused to tell us where to site
1376                                  * the mapping so we'll have to attempt to copy
1377                                  * it */
1378                                 ret = -ENODEV;
1379                                 if (!(capabilities & BDI_CAP_MAP_COPY))
1380                                         goto error_just_free;
1381
1382                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
1383                         } else {
1384                                 vma->vm_start = region->vm_start = addr;
1385                                 vma->vm_end = region->vm_end = addr + len;
1386                         }
1387                 }
1388         }
1389
1390         vma->vm_region = region;
1391
1392         /* set up the mapping
1393          * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1394          */
1395         if (file && vma->vm_flags & VM_SHARED)
1396                 ret = do_mmap_shared_file(vma);
1397         else
1398                 ret = do_mmap_private(vma, region, len, capabilities);
1399         if (ret < 0)
1400                 goto error_just_free;
1401         add_nommu_region(region);
1402
1403         /* clear anonymous mappings that don't ask for uninitialized data */
1404         if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1405                 memset((void *)region->vm_start, 0,
1406                        region->vm_end - region->vm_start);
1407
1408         /* okay... we have a mapping; now we have to register it */
1409         result = vma->vm_start;
1410
1411         current->mm->total_vm += len >> PAGE_SHIFT;
1412
1413 share:
1414         add_vma_to_mm(current->mm, vma);
1415
1416         /* we flush the region from the icache only when the first executable
1417          * mapping of it is made  */
1418         if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1419                 flush_icache_range(region->vm_start, region->vm_end);
1420                 region->vm_icache_flushed = true;
1421         }
1422
1423         up_write(&nommu_region_sem);
1424
1425         kleave(" = %lx", result);
1426         return result;
1427
1428 error_just_free:
1429         up_write(&nommu_region_sem);
1430 error:
1431         if (region->vm_file)
1432                 fput(region->vm_file);
1433         kmem_cache_free(vm_region_jar, region);
1434         if (vma->vm_file)
1435                 fput(vma->vm_file);
1436         kmem_cache_free(vm_area_cachep, vma);
1437         kleave(" = %d", ret);
1438         return ret;
1439
1440 sharing_violation:
1441         up_write(&nommu_region_sem);
1442         printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1443         ret = -EINVAL;
1444         goto error;
1445
1446 error_getting_vma:
1447         kmem_cache_free(vm_region_jar, region);
1448         printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1449                " from process %d failed\n",
1450                len, current->pid);
1451         show_free_areas(0);
1452         return -ENOMEM;
1453
1454 error_getting_region:
1455         printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1456                " from process %d failed\n",
1457                len, current->pid);
1458         show_free_areas(0);
1459         return -ENOMEM;
1460 }
1461
1462 SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1463                 unsigned long, prot, unsigned long, flags,
1464                 unsigned long, fd, unsigned long, pgoff)
1465 {
1466         struct file *file = NULL;
1467         unsigned long retval = -EBADF;
1468
1469         audit_mmap_fd(fd, flags);
1470         if (!(flags & MAP_ANONYMOUS)) {
1471                 file = fget(fd);
1472                 if (!file)
1473                         goto out;
1474         }
1475
1476         flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1477
1478         retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1479
1480         if (file)
1481                 fput(file);
1482 out:
1483         return retval;
1484 }
1485
1486 #ifdef __ARCH_WANT_SYS_OLD_MMAP
1487 struct mmap_arg_struct {
1488         unsigned long addr;
1489         unsigned long len;
1490         unsigned long prot;
1491         unsigned long flags;
1492         unsigned long fd;
1493         unsigned long offset;
1494 };
1495
1496 SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1497 {
1498         struct mmap_arg_struct a;
1499
1500         if (copy_from_user(&a, arg, sizeof(a)))
1501                 return -EFAULT;
1502         if (a.offset & ~PAGE_MASK)
1503                 return -EINVAL;
1504
1505         return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1506                               a.offset >> PAGE_SHIFT);
1507 }
1508 #endif /* __ARCH_WANT_SYS_OLD_MMAP */
1509
1510 /*
1511  * split a vma into two pieces at address 'addr', a new vma is allocated either
1512  * for the first part or the tail.
1513  */
1514 int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1515               unsigned long addr, int new_below)
1516 {
1517         struct vm_area_struct *new;
1518         struct vm_region *region;
1519         unsigned long npages;
1520
1521         kenter("");
1522
1523         /* we're only permitted to split anonymous regions (these should have
1524          * only a single usage on the region) */
1525         if (vma->vm_file)
1526                 return -ENOMEM;
1527
1528         if (mm->map_count >= sysctl_max_map_count)
1529                 return -ENOMEM;
1530
1531         region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1532         if (!region)
1533                 return -ENOMEM;
1534
1535         new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1536         if (!new) {
1537                 kmem_cache_free(vm_region_jar, region);
1538                 return -ENOMEM;
1539         }
1540
1541         /* most fields are the same, copy all, and then fixup */
1542         *new = *vma;
1543         *region = *vma->vm_region;
1544         new->vm_region = region;
1545
1546         npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1547
1548         if (new_below) {
1549                 region->vm_top = region->vm_end = new->vm_end = addr;
1550         } else {
1551                 region->vm_start = new->vm_start = addr;
1552                 region->vm_pgoff = new->vm_pgoff += npages;
1553         }
1554
1555         if (new->vm_ops && new->vm_ops->open)
1556                 new->vm_ops->open(new);
1557
1558         delete_vma_from_mm(vma);
1559         down_write(&nommu_region_sem);
1560         delete_nommu_region(vma->vm_region);
1561         if (new_below) {
1562                 vma->vm_region->vm_start = vma->vm_start = addr;
1563                 vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1564         } else {
1565                 vma->vm_region->vm_end = vma->vm_end = addr;
1566                 vma->vm_region->vm_top = addr;
1567         }
1568         add_nommu_region(vma->vm_region);
1569         add_nommu_region(new->vm_region);
1570         up_write(&nommu_region_sem);
1571         add_vma_to_mm(mm, vma);
1572         add_vma_to_mm(mm, new);
1573         return 0;
1574 }
1575
1576 /*
1577  * shrink a VMA by removing the specified chunk from either the beginning or
1578  * the end
1579  */
1580 static int shrink_vma(struct mm_struct *mm,
1581                       struct vm_area_struct *vma,
1582                       unsigned long from, unsigned long to)
1583 {
1584         struct vm_region *region;
1585
1586         kenter("");
1587
1588         /* adjust the VMA's pointers, which may reposition it in the MM's tree
1589          * and list */
1590         delete_vma_from_mm(vma);
1591         if (from > vma->vm_start)
1592                 vma->vm_end = from;
1593         else
1594                 vma->vm_start = to;
1595         add_vma_to_mm(mm, vma);
1596
1597         /* cut the backing region down to size */
1598         region = vma->vm_region;
1599         BUG_ON(region->vm_usage != 1);
1600
1601         down_write(&nommu_region_sem);
1602         delete_nommu_region(region);
1603         if (from > region->vm_start) {
1604                 to = region->vm_top;
1605                 region->vm_top = region->vm_end = from;
1606         } else {
1607                 region->vm_start = to;
1608         }
1609         add_nommu_region(region);
1610         up_write(&nommu_region_sem);
1611
1612         free_page_series(from, to);
1613         return 0;
1614 }
1615
1616 /*
1617  * release a mapping
1618  * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1619  *   VMA, though it need not cover the whole VMA
1620  */
1621 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1622 {
1623         struct vm_area_struct *vma;
1624         unsigned long end;
1625         int ret;
1626
1627         kenter(",%lx,%zx", start, len);
1628
1629         len = PAGE_ALIGN(len);
1630         if (len == 0)
1631                 return -EINVAL;
1632
1633         end = start + len;
1634
1635         /* find the first potentially overlapping VMA */
1636         vma = find_vma(mm, start);
1637         if (!vma) {
1638                 static int limit = 0;
1639                 if (limit < 5) {
1640                         printk(KERN_WARNING
1641                                "munmap of memory not mmapped by process %d"
1642                                " (%s): 0x%lx-0x%lx\n",
1643                                current->pid, current->comm,
1644                                start, start + len - 1);
1645                         limit++;
1646                 }
1647                 return -EINVAL;
1648         }
1649
1650         /* we're allowed to split an anonymous VMA but not a file-backed one */
1651         if (vma->vm_file) {
1652                 do {
1653                         if (start > vma->vm_start) {
1654                                 kleave(" = -EINVAL [miss]");
1655                                 return -EINVAL;
1656                         }
1657                         if (end == vma->vm_end)
1658                                 goto erase_whole_vma;
1659                         vma = vma->vm_next;
1660                 } while (vma);
1661                 kleave(" = -EINVAL [split file]");
1662                 return -EINVAL;
1663         } else {
1664                 /* the chunk must be a subset of the VMA found */
1665                 if (start == vma->vm_start && end == vma->vm_end)
1666                         goto erase_whole_vma;
1667                 if (start < vma->vm_start || end > vma->vm_end) {
1668                         kleave(" = -EINVAL [superset]");
1669                         return -EINVAL;
1670                 }
1671                 if (start & ~PAGE_MASK) {
1672                         kleave(" = -EINVAL [unaligned start]");
1673                         return -EINVAL;
1674                 }
1675                 if (end != vma->vm_end && end & ~PAGE_MASK) {
1676                         kleave(" = -EINVAL [unaligned split]");
1677                         return -EINVAL;
1678                 }
1679                 if (start != vma->vm_start && end != vma->vm_end) {
1680                         ret = split_vma(mm, vma, start, 1);
1681                         if (ret < 0) {
1682                                 kleave(" = %d [split]", ret);
1683                                 return ret;
1684                         }
1685                 }
1686                 return shrink_vma(mm, vma, start, end);
1687         }
1688
1689 erase_whole_vma:
1690         delete_vma_from_mm(vma);
1691         delete_vma(mm, vma);
1692         kleave(" = 0");
1693         return 0;
1694 }
1695 EXPORT_SYMBOL(do_munmap);
1696
1697 int vm_munmap(unsigned long addr, size_t len)
1698 {
1699         struct mm_struct *mm = current->mm;
1700         int ret;
1701
1702         down_write(&mm->mmap_sem);
1703         ret = do_munmap(mm, addr, len);
1704         up_write(&mm->mmap_sem);
1705         return ret;
1706 }
1707 EXPORT_SYMBOL(vm_munmap);
1708
1709 SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1710 {
1711         return vm_munmap(addr, len);
1712 }
1713
1714 /*
1715  * release all the mappings made in a process's VM space
1716  */
1717 void exit_mmap(struct mm_struct *mm)
1718 {
1719         struct vm_area_struct *vma;
1720
1721         if (!mm)
1722                 return;
1723
1724         kenter("");
1725
1726         mm->total_vm = 0;
1727
1728         while ((vma = mm->mmap)) {
1729                 mm->mmap = vma->vm_next;
1730                 delete_vma_from_mm(vma);
1731                 delete_vma(mm, vma);
1732                 cond_resched();
1733         }
1734
1735         kleave("");
1736 }
1737
1738 unsigned long vm_brk(unsigned long addr, unsigned long len)
1739 {
1740         return -ENOMEM;
1741 }
1742
1743 /*
1744  * expand (or shrink) an existing mapping, potentially moving it at the same
1745  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1746  *
1747  * under NOMMU conditions, we only permit changing a mapping's size, and only
1748  * as long as it stays within the region allocated by do_mmap_private() and the
1749  * block is not shareable
1750  *
1751  * MREMAP_FIXED is not supported under NOMMU conditions
1752  */
1753 unsigned long do_mremap(unsigned long addr,
1754                         unsigned long old_len, unsigned long new_len,
1755                         unsigned long flags, unsigned long new_addr)
1756 {
1757         struct vm_area_struct *vma;
1758
1759         /* insanity checks first */
1760         old_len = PAGE_ALIGN(old_len);
1761         new_len = PAGE_ALIGN(new_len);
1762         if (old_len == 0 || new_len == 0)
1763                 return (unsigned long) -EINVAL;
1764
1765         if (addr & ~PAGE_MASK)
1766                 return -EINVAL;
1767
1768         if (flags & MREMAP_FIXED && new_addr != addr)
1769                 return (unsigned long) -EINVAL;
1770
1771         vma = find_vma_exact(current->mm, addr, old_len);
1772         if (!vma)
1773                 return (unsigned long) -EINVAL;
1774
1775         if (vma->vm_end != vma->vm_start + old_len)
1776                 return (unsigned long) -EFAULT;
1777
1778         if (vma->vm_flags & VM_MAYSHARE)
1779                 return (unsigned long) -EPERM;
1780
1781         if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1782                 return (unsigned long) -ENOMEM;
1783
1784         /* all checks complete - do it */
1785         vma->vm_end = vma->vm_start + new_len;
1786         return vma->vm_start;
1787 }
1788 EXPORT_SYMBOL(do_mremap);
1789
1790 SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1791                 unsigned long, new_len, unsigned long, flags,
1792                 unsigned long, new_addr)
1793 {
1794         unsigned long ret;
1795
1796         down_write(&current->mm->mmap_sem);
1797         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1798         up_write(&current->mm->mmap_sem);
1799         return ret;
1800 }
1801
1802 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1803                         unsigned int foll_flags)
1804 {
1805         return NULL;
1806 }
1807
1808 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1809                 unsigned long pfn, unsigned long size, pgprot_t prot)
1810 {
1811         if (addr != (pfn << PAGE_SHIFT))
1812                 return -EINVAL;
1813
1814         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1815         return 0;
1816 }
1817 EXPORT_SYMBOL(remap_pfn_range);
1818
1819 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1820                         unsigned long pgoff)
1821 {
1822         unsigned int size = vma->vm_end - vma->vm_start;
1823
1824         if (!(vma->vm_flags & VM_USERMAP))
1825                 return -EINVAL;
1826
1827         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1828         vma->vm_end = vma->vm_start + size;
1829
1830         return 0;
1831 }
1832 EXPORT_SYMBOL(remap_vmalloc_range);
1833
1834 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1835         unsigned long len, unsigned long pgoff, unsigned long flags)
1836 {
1837         return -ENOMEM;
1838 }
1839
1840 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1841 {
1842 }
1843
1844 void unmap_mapping_range(struct address_space *mapping,
1845                          loff_t const holebegin, loff_t const holelen,
1846                          int even_cows)
1847 {
1848 }
1849 EXPORT_SYMBOL(unmap_mapping_range);
1850
1851 /*
1852  * Check that a process has enough memory to allocate a new virtual
1853  * mapping. 0 means there is enough memory for the allocation to
1854  * succeed and -ENOMEM implies there is not.
1855  *
1856  * We currently support three overcommit policies, which are set via the
1857  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1858  *
1859  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1860  * Additional code 2002 Jul 20 by Robert Love.
1861  *
1862  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1863  *
1864  * Note this is a helper function intended to be used by LSMs which
1865  * wish to use this logic.
1866  */
1867 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1868 {
1869         unsigned long free, allowed;
1870
1871         vm_acct_memory(pages);
1872
1873         /*
1874          * Sometimes we want to use more memory than we have
1875          */
1876         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1877                 return 0;
1878
1879         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1880                 free = global_page_state(NR_FREE_PAGES);
1881                 free += global_page_state(NR_FILE_PAGES);
1882
1883                 /*
1884                  * shmem pages shouldn't be counted as free in this
1885                  * case, they can't be purged, only swapped out, and
1886                  * that won't affect the overall amount of available
1887                  * memory in the system.
1888                  */
1889                 free -= global_page_state(NR_SHMEM);
1890
1891                 free += nr_swap_pages;
1892
1893                 /*
1894                  * Any slabs which are created with the
1895                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1896                  * which are reclaimable, under pressure.  The dentry
1897                  * cache and most inode caches should fall into this
1898                  */
1899                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1900
1901                 /*
1902                  * Leave reserved pages. The pages are not for anonymous pages.
1903                  */
1904                 if (free <= totalreserve_pages)
1905                         goto error;
1906                 else
1907                         free -= totalreserve_pages;
1908
1909                 /*
1910                  * Leave the last 3% for root
1911                  */
1912                 if (!cap_sys_admin)
1913                         free -= free / 32;
1914
1915                 if (free > pages)
1916                         return 0;
1917
1918                 goto error;
1919         }
1920
1921         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1922         /*
1923          * Leave the last 3% for root
1924          */
1925         if (!cap_sys_admin)
1926                 allowed -= allowed / 32;
1927         allowed += total_swap_pages;
1928
1929         /* Don't let a single process grow too big:
1930            leave 3% of the size of this process for other processes */
1931         if (mm)
1932                 allowed -= mm->total_vm / 32;
1933
1934         if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1935                 return 0;
1936
1937 error:
1938         vm_unacct_memory(pages);
1939
1940         return -ENOMEM;
1941 }
1942
1943 int in_gate_area_no_mm(unsigned long addr)
1944 {
1945         return 0;
1946 }
1947
1948 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1949 {
1950         BUG();
1951         return 0;
1952 }
1953 EXPORT_SYMBOL(filemap_fault);
1954
1955 int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
1956                              unsigned long size, pgoff_t pgoff)
1957 {
1958         BUG();
1959         return 0;
1960 }
1961 EXPORT_SYMBOL(generic_file_remap_pages);
1962
1963 static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1964                 unsigned long addr, void *buf, int len, int write)
1965 {
1966         struct vm_area_struct *vma;
1967
1968         down_read(&mm->mmap_sem);
1969
1970         /* the access must start within one of the target process's mappings */
1971         vma = find_vma(mm, addr);
1972         if (vma) {
1973                 /* don't overrun this mapping */
1974                 if (addr + len >= vma->vm_end)
1975                         len = vma->vm_end - addr;
1976
1977                 /* only read or write mappings where it is permitted */
1978                 if (write && vma->vm_flags & VM_MAYWRITE)
1979                         copy_to_user_page(vma, NULL, addr,
1980                                          (void *) addr, buf, len);
1981                 else if (!write && vma->vm_flags & VM_MAYREAD)
1982                         copy_from_user_page(vma, NULL, addr,
1983                                             buf, (void *) addr, len);
1984                 else
1985                         len = 0;
1986         } else {
1987                 len = 0;
1988         }
1989
1990         up_read(&mm->mmap_sem);
1991
1992         return len;
1993 }
1994
1995 /**
1996  * @access_remote_vm - access another process' address space
1997  * @mm:         the mm_struct of the target address space
1998  * @addr:       start address to access
1999  * @buf:        source or destination buffer
2000  * @len:        number of bytes to transfer
2001  * @write:      whether the access is a write
2002  *
2003  * The caller must hold a reference on @mm.
2004  */
2005 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2006                 void *buf, int len, int write)
2007 {
2008         return __access_remote_vm(NULL, mm, addr, buf, len, write);
2009 }
2010
2011 /*
2012  * Access another process' address space.
2013  * - source/target buffer must be kernel space
2014  */
2015 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2016 {
2017         struct mm_struct *mm;
2018
2019         if (addr + len < addr)
2020                 return 0;
2021
2022         mm = get_task_mm(tsk);
2023         if (!mm)
2024                 return 0;
2025
2026         len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2027
2028         mmput(mm);
2029         return len;
2030 }
2031
2032 /**
2033  * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2034  * @inode: The inode to check
2035  * @size: The current filesize of the inode
2036  * @newsize: The proposed filesize of the inode
2037  *
2038  * Check the shared mappings on an inode on behalf of a shrinking truncate to
2039  * make sure that that any outstanding VMAs aren't broken and then shrink the
2040  * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2041  * automatically grant mappings that are too large.
2042  */
2043 int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2044                                 size_t newsize)
2045 {
2046         struct vm_area_struct *vma;
2047         struct vm_region *region;
2048         pgoff_t low, high;
2049         size_t r_size, r_top;
2050
2051         low = newsize >> PAGE_SHIFT;
2052         high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2053
2054         down_write(&nommu_region_sem);
2055         mutex_lock(&inode->i_mapping->i_mmap_mutex);
2056
2057         /* search for VMAs that fall within the dead zone */
2058         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
2059                 /* found one - only interested if it's shared out of the page
2060                  * cache */
2061                 if (vma->vm_flags & VM_SHARED) {
2062                         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2063                         up_write(&nommu_region_sem);
2064                         return -ETXTBSY; /* not quite true, but near enough */
2065                 }
2066         }
2067
2068         /* reduce any regions that overlap the dead zone - if in existence,
2069          * these will be pointed to by VMAs that don't overlap the dead zone
2070          *
2071          * we don't check for any regions that start beyond the EOF as there
2072          * shouldn't be any
2073          */
2074         vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
2075                                   0, ULONG_MAX) {
2076                 if (!(vma->vm_flags & VM_SHARED))
2077                         continue;
2078
2079                 region = vma->vm_region;
2080                 r_size = region->vm_top - region->vm_start;
2081                 r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2082
2083                 if (r_top > newsize) {
2084                         region->vm_top -= r_top - newsize;
2085                         if (region->vm_end > region->vm_top)
2086                                 region->vm_end = region->vm_top;
2087                 }
2088         }
2089
2090         mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2091         up_write(&nommu_region_sem);
2092         return 0;
2093 }