linux/mm/nommu.c
<<
>>
Prefs
   1/*
   2 *  linux/mm/nommu.c
   3 *
   4 *  Replacement code for mm functions to support CPU's that don't
   5 *  have any form of memory management unit (thus no virtual memory).
   6 *
   7 *  See Documentation/nommu-mmap.txt
   8 *
   9 *  Copyright (c) 2004-2008 David Howells <dhowells@redhat.com>
  10 *  Copyright (c) 2000-2003 David McCullough <davidm@snapgear.com>
  11 *  Copyright (c) 2000-2001 D Jeff Dionne <jeff@uClinux.org>
  12 *  Copyright (c) 2002      Greg Ungerer <gerg@snapgear.com>
  13 *  Copyright (c) 2007-2010 Paul Mundt <lethal@linux-sh.org>
  14 */
  15
  16#include <linux/export.h>
  17#include <linux/mm.h>
  18#include <linux/mman.h>
  19#include <linux/swap.h>
  20#include <linux/file.h>
  21#include <linux/highmem.h>
  22#include <linux/pagemap.h>
  23#include <linux/slab.h>
  24#include <linux/vmalloc.h>
  25#include <linux/blkdev.h>
  26#include <linux/backing-dev.h>
  27#include <linux/mount.h>
  28#include <linux/personality.h>
  29#include <linux/security.h>
  30#include <linux/syscalls.h>
  31#include <linux/audit.h>
  32#include <linux/sched/sysctl.h>
  33
  34#include <asm/uaccess.h>
  35#include <asm/tlb.h>
  36#include <asm/tlbflush.h>
  37#include <asm/mmu_context.h>
  38#include "internal.h"
  39
  40#if 0
  41#define kenter(FMT, ...) \
  42        printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  43#define kleave(FMT, ...) \
  44        printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  45#define kdebug(FMT, ...) \
  46        printk(KERN_DEBUG "xxx" FMT"yyy\n", ##__VA_ARGS__)
  47#else
  48#define kenter(FMT, ...) \
  49        no_printk(KERN_DEBUG "==> %s("FMT")\n", __func__, ##__VA_ARGS__)
  50#define kleave(FMT, ...) \
  51        no_printk(KERN_DEBUG "<== %s()"FMT"\n", __func__, ##__VA_ARGS__)
  52#define kdebug(FMT, ...) \
  53        no_printk(KERN_DEBUG FMT"\n", ##__VA_ARGS__)
  54#endif
  55
  56void *high_memory;
  57struct page *mem_map;
  58unsigned long max_mapnr;
  59unsigned long num_physpages;
  60unsigned long highest_memmap_pfn;
  61struct percpu_counter vm_committed_as;
  62int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  63int sysctl_overcommit_ratio = 50; /* default is 50% */
  64int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  65int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
  66int heap_stack_gap = 0;
  67
  68atomic_long_t mmap_pages_allocated;
  69
  70/*
  71 * The global memory commitment made in the system can be a metric
  72 * that can be used to drive ballooning decisions when Linux is hosted
  73 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
  74 * balancing memory across competing virtual machines that are hosted.
  75 * Several metrics drive this policy engine including the guest reported
  76 * memory commitment.
  77 */
  78unsigned long vm_memory_committed(void)
  79{
  80        return percpu_counter_read_positive(&vm_committed_as);
  81}
  82
  83EXPORT_SYMBOL_GPL(vm_memory_committed);
  84
  85EXPORT_SYMBOL(mem_map);
  86EXPORT_SYMBOL(num_physpages);
  87
  88/* list of mapped, potentially shareable regions */
  89static struct kmem_cache *vm_region_jar;
  90struct rb_root nommu_region_tree = RB_ROOT;
  91DECLARE_RWSEM(nommu_region_sem);
  92
  93const struct vm_operations_struct generic_file_vm_ops = {
  94};
  95
  96/*
  97 * Return the total memory allocated for this pointer, not
  98 * just what the caller asked for.
  99 *
 100 * Doesn't have to be accurate, i.e. may have races.
 101 */
 102unsigned int kobjsize(const void *objp)
 103{
 104        struct page *page;
 105
 106        /*
 107         * If the object we have should not have ksize performed on it,
 108         * return size of 0
 109         */
 110        if (!objp || !virt_addr_valid(objp))
 111                return 0;
 112
 113        page = virt_to_head_page(objp);
 114
 115        /*
 116         * If the allocator sets PageSlab, we know the pointer came from
 117         * kmalloc().
 118         */
 119        if (PageSlab(page))
 120                return ksize(objp);
 121
 122        /*
 123         * If it's not a compound page, see if we have a matching VMA
 124         * region. This test is intentionally done in reverse order,
 125         * so if there's no VMA, we still fall through and hand back
 126         * PAGE_SIZE for 0-order pages.
 127         */
 128        if (!PageCompound(page)) {
 129                struct vm_area_struct *vma;
 130
 131                vma = find_vma(current->mm, (unsigned long)objp);
 132                if (vma)
 133                        return vma->vm_end - vma->vm_start;
 134        }
 135
 136        /*
 137         * The ksize() function is only guaranteed to work for pointers
 138         * returned by kmalloc(). So handle arbitrary pointers here.
 139         */
 140        return PAGE_SIZE << compound_order(page);
 141}
 142
 143long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 144                      unsigned long start, unsigned long nr_pages,
 145                      unsigned int foll_flags, struct page **pages,
 146                      struct vm_area_struct **vmas, int *nonblocking)
 147{
 148        struct vm_area_struct *vma;
 149        unsigned long vm_flags;
 150        int i;
 151
 152        /* calculate required read or write permissions.
 153         * If FOLL_FORCE is set, we only require the "MAY" flags.
 154         */
 155        vm_flags  = (foll_flags & FOLL_WRITE) ?
 156                        (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 157        vm_flags &= (foll_flags & FOLL_FORCE) ?
 158                        (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 159
 160        for (i = 0; i < nr_pages; i++) {
 161                vma = find_vma(mm, start);
 162                if (!vma)
 163                        goto finish_or_fault;
 164
 165                /* protect what we can, including chardevs */
 166                if ((vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
 167                    !(vm_flags & vma->vm_flags))
 168                        goto finish_or_fault;
 169
 170                if (pages) {
 171                        pages[i] = virt_to_page(start);
 172                        if (pages[i])
 173                                page_cache_get(pages[i]);
 174                }
 175                if (vmas)
 176                        vmas[i] = vma;
 177                start = (start + PAGE_SIZE) & PAGE_MASK;
 178        }
 179
 180        return i;
 181
 182finish_or_fault:
 183        return i ? : -EFAULT;
 184}
 185
 186/*
 187 * get a list of pages in an address range belonging to the specified process
 188 * and indicate the VMA that covers each page
 189 * - this is potentially dodgy as we may end incrementing the page count of a
 190 *   slab page or a secondary page from a compound page
 191 * - don't permit access to VMAs that don't support it, such as I/O mappings
 192 */
 193long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 194                    unsigned long start, unsigned long nr_pages,
 195                    int write, int force, struct page **pages,
 196                    struct vm_area_struct **vmas)
 197{
 198        int flags = 0;
 199
 200        if (write)
 201                flags |= FOLL_WRITE;
 202        if (force)
 203                flags |= FOLL_FORCE;
 204
 205        return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
 206                                NULL);
 207}
 208EXPORT_SYMBOL(get_user_pages);
 209
 210/**
 211 * follow_pfn - look up PFN at a user virtual address
 212 * @vma: memory mapping
 213 * @address: user virtual address
 214 * @pfn: location to store found PFN
 215 *
 216 * Only IO mappings and raw PFN mappings are allowed.
 217 *
 218 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 219 */
 220int follow_pfn(struct vm_area_struct *vma, unsigned long address,
 221        unsigned long *pfn)
 222{
 223        if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
 224                return -EINVAL;
 225
 226        *pfn = address >> PAGE_SHIFT;
 227        return 0;
 228}
 229EXPORT_SYMBOL(follow_pfn);
 230
 231DEFINE_RWLOCK(vmlist_lock);
 232struct vm_struct *vmlist;
 233
 234void vfree(const void *addr)
 235{
 236        kfree(addr);
 237}
 238EXPORT_SYMBOL(vfree);
 239
 240void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 241{
 242        /*
 243         *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 244         * returns only a logical address.
 245         */
 246        return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 247}
 248EXPORT_SYMBOL(__vmalloc);
 249
 250void *vmalloc_user(unsigned long size)
 251{
 252        void *ret;
 253
 254        ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 255                        PAGE_KERNEL);
 256        if (ret) {
 257                struct vm_area_struct *vma;
 258
 259                down_write(&current->mm->mmap_sem);
 260                vma = find_vma(current->mm, (unsigned long)ret);
 261                if (vma)
 262                        vma->vm_flags |= VM_USERMAP;
 263                up_write(&current->mm->mmap_sem);
 264        }
 265
 266        return ret;
 267}
 268EXPORT_SYMBOL(vmalloc_user);
 269
 270struct page *vmalloc_to_page(const void *addr)
 271{
 272        return virt_to_page(addr);
 273}
 274EXPORT_SYMBOL(vmalloc_to_page);
 275
 276unsigned long vmalloc_to_pfn(const void *addr)
 277{
 278        return page_to_pfn(virt_to_page(addr));
 279}
 280EXPORT_SYMBOL(vmalloc_to_pfn);
 281
 282long vread(char *buf, char *addr, unsigned long count)
 283{
 284        memcpy(buf, addr, count);
 285        return count;
 286}
 287
 288long vwrite(char *buf, char *addr, unsigned long count)
 289{
 290        /* Don't allow overflow */
 291        if ((unsigned long) addr + count < count)
 292                count = -(unsigned long) addr;
 293
 294        memcpy(addr, buf, count);
 295        return(count);
 296}
 297
 298/*
 299 *      vmalloc  -  allocate virtually continguos memory
 300 *
 301 *      @size:          allocation size
 302 *
 303 *      Allocate enough pages to cover @size from the page level
 304 *      allocator and map them into continguos kernel virtual space.
 305 *
 306 *      For tight control over page level allocator and protection flags
 307 *      use __vmalloc() instead.
 308 */
 309void *vmalloc(unsigned long size)
 310{
 311       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 312}
 313EXPORT_SYMBOL(vmalloc);
 314
 315/*
 316 *      vzalloc - allocate virtually continguos memory with zero fill
 317 *
 318 *      @size:          allocation size
 319 *
 320 *      Allocate enough pages to cover @size from the page level
 321 *      allocator and map them into continguos kernel virtual space.
 322 *      The memory allocated is set to zero.
 323 *
 324 *      For tight control over page level allocator and protection flags
 325 *      use __vmalloc() instead.
 326 */
 327void *vzalloc(unsigned long size)
 328{
 329        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 330                        PAGE_KERNEL);
 331}
 332EXPORT_SYMBOL(vzalloc);
 333
 334/**
 335 * vmalloc_node - allocate memory on a specific node
 336 * @size:       allocation size
 337 * @node:       numa node
 338 *
 339 * Allocate enough pages to cover @size from the page level
 340 * allocator and map them into contiguous kernel virtual space.
 341 *
 342 * For tight control over page level allocator and protection flags
 343 * use __vmalloc() instead.
 344 */
 345void *vmalloc_node(unsigned long size, int node)
 346{
 347        return vmalloc(size);
 348}
 349EXPORT_SYMBOL(vmalloc_node);
 350
 351/**
 352 * vzalloc_node - allocate memory on a specific node with zero fill
 353 * @size:       allocation size
 354 * @node:       numa node
 355 *
 356 * Allocate enough pages to cover @size from the page level
 357 * allocator and map them into contiguous kernel virtual space.
 358 * The memory allocated is set to zero.
 359 *
 360 * For tight control over page level allocator and protection flags
 361 * use __vmalloc() instead.
 362 */
 363void *vzalloc_node(unsigned long size, int node)
 364{
 365        return vzalloc(size);
 366}
 367EXPORT_SYMBOL(vzalloc_node);
 368
 369#ifndef PAGE_KERNEL_EXEC
 370# define PAGE_KERNEL_EXEC PAGE_KERNEL
 371#endif
 372
 373/**
 374 *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 375 *      @size:          allocation size
 376 *
 377 *      Kernel-internal function to allocate enough pages to cover @size
 378 *      the page level allocator and map them into contiguous and
 379 *      executable kernel virtual space.
 380 *
 381 *      For tight control over page level allocator and protection flags
 382 *      use __vmalloc() instead.
 383 */
 384
 385void *vmalloc_exec(unsigned long size)
 386{
 387        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 388}
 389
 390/**
 391 * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 392 *      @size:          allocation size
 393 *
 394 *      Allocate enough 32bit PA addressable pages to cover @size from the
 395 *      page level allocator and map them into continguos kernel virtual space.
 396 */
 397void *vmalloc_32(unsigned long size)
 398{
 399        return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 400}
 401EXPORT_SYMBOL(vmalloc_32);
 402
 403/**
 404 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 405 *      @size:          allocation size
 406 *
 407 * The resulting memory area is 32bit addressable and zeroed so it can be
 408 * mapped to userspace without leaking data.
 409 *
 410 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 411 * remap_vmalloc_range() are permissible.
 412 */
 413void *vmalloc_32_user(unsigned long size)
 414{
 415        /*
 416         * We'll have to sort out the ZONE_DMA bits for 64-bit,
 417         * but for now this can simply use vmalloc_user() directly.
 418         */
 419        return vmalloc_user(size);
 420}
 421EXPORT_SYMBOL(vmalloc_32_user);
 422
 423void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 424{
 425        BUG();
 426        return NULL;
 427}
 428EXPORT_SYMBOL(vmap);
 429
 430void vunmap(const void *addr)
 431{
 432        BUG();
 433}
 434EXPORT_SYMBOL(vunmap);
 435
 436void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
 437{
 438        BUG();
 439        return NULL;
 440}
 441EXPORT_SYMBOL(vm_map_ram);
 442
 443void vm_unmap_ram(const void *mem, unsigned int count)
 444{
 445        BUG();
 446}
 447EXPORT_SYMBOL(vm_unmap_ram);
 448
 449void vm_unmap_aliases(void)
 450{
 451}
 452EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 453
 454/*
 455 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 456 * have one.
 457 */
 458void  __attribute__((weak)) vmalloc_sync_all(void)
 459{
 460}
 461
 462/**
 463 *      alloc_vm_area - allocate a range of kernel address space
 464 *      @size:          size of the area
 465 *
 466 *      Returns:        NULL on failure, vm_struct on success
 467 *
 468 *      This function reserves a range of kernel address space, and
 469 *      allocates pagetables to map that range.  No actual mappings
 470 *      are created.  If the kernel address space is not shared
 471 *      between processes, it syncs the pagetable across all
 472 *      processes.
 473 */
 474struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
 475{
 476        BUG();
 477        return NULL;
 478}
 479EXPORT_SYMBOL_GPL(alloc_vm_area);
 480
 481void free_vm_area(struct vm_struct *area)
 482{
 483        BUG();
 484}
 485EXPORT_SYMBOL_GPL(free_vm_area);
 486
 487int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 488                   struct page *page)
 489{
 490        return -EINVAL;
 491}
 492EXPORT_SYMBOL(vm_insert_page);
 493
 494/*
 495 *  sys_brk() for the most part doesn't need the global kernel
 496 *  lock, except when an application is doing something nasty
 497 *  like trying to un-brk an area that has already been mapped
 498 *  to a regular file.  in this case, the unmapping will need
 499 *  to invoke file system routines that need the global lock.
 500 */
 501SYSCALL_DEFINE1(brk, unsigned long, brk)
 502{
 503        struct mm_struct *mm = current->mm;
 504
 505        if (brk < mm->start_brk || brk > mm->context.end_brk)
 506                return mm->brk;
 507
 508        if (mm->brk == brk)
 509                return mm->brk;
 510
 511        /*
 512         * Always allow shrinking brk
 513         */
 514        if (brk <= mm->brk) {
 515                mm->brk = brk;
 516                return brk;
 517        }
 518
 519        /*
 520         * Ok, looks good - let it rip.
 521         */
 522        flush_icache_range(mm->brk, brk);
 523        return mm->brk = brk;
 524}
 525
 526/*
 527 * initialise the VMA and region record slabs
 528 */
 529void __init mmap_init(void)
 530{
 531        int ret;
 532
 533        ret = percpu_counter_init(&vm_committed_as, 0);
 534        VM_BUG_ON(ret);
 535        vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
 536}
 537
 538/*
 539 * validate the region tree
 540 * - the caller must hold the region lock
 541 */
 542#ifdef CONFIG_DEBUG_NOMMU_REGIONS
 543static noinline void validate_nommu_regions(void)
 544{
 545        struct vm_region *region, *last;
 546        struct rb_node *p, *lastp;
 547
 548        lastp = rb_first(&nommu_region_tree);
 549        if (!lastp)
 550                return;
 551
 552        last = rb_entry(lastp, struct vm_region, vm_rb);
 553        BUG_ON(unlikely(last->vm_end <= last->vm_start));
 554        BUG_ON(unlikely(last->vm_top < last->vm_end));
 555
 556        while ((p = rb_next(lastp))) {
 557                region = rb_entry(p, struct vm_region, vm_rb);
 558                last = rb_entry(lastp, struct vm_region, vm_rb);
 559
 560                BUG_ON(unlikely(region->vm_end <= region->vm_start));
 561                BUG_ON(unlikely(region->vm_top < region->vm_end));
 562                BUG_ON(unlikely(region->vm_start < last->vm_top));
 563
 564                lastp = p;
 565        }
 566}
 567#else
 568static void validate_nommu_regions(void)
 569{
 570}
 571#endif
 572
 573/*
 574 * add a region into the global tree
 575 */
 576static void add_nommu_region(struct vm_region *region)
 577{
 578        struct vm_region *pregion;
 579        struct rb_node **p, *parent;
 580
 581        validate_nommu_regions();
 582
 583        parent = NULL;
 584        p = &nommu_region_tree.rb_node;
 585        while (*p) {
 586                parent = *p;
 587                pregion = rb_entry(parent, struct vm_region, vm_rb);
 588                if (region->vm_start < pregion->vm_start)
 589                        p = &(*p)->rb_left;
 590                else if (region->vm_start > pregion->vm_start)
 591                        p = &(*p)->rb_right;
 592                else if (pregion == region)
 593                        return;
 594                else
 595                        BUG();
 596        }
 597
 598        rb_link_node(&region->vm_rb, parent, p);
 599        rb_insert_color(&region->vm_rb, &nommu_region_tree);
 600
 601        validate_nommu_regions();
 602}
 603
 604/*
 605 * delete a region from the global tree
 606 */
 607static void delete_nommu_region(struct vm_region *region)
 608{
 609        BUG_ON(!nommu_region_tree.rb_node);
 610
 611        validate_nommu_regions();
 612        rb_erase(&region->vm_rb, &nommu_region_tree);
 613        validate_nommu_regions();
 614}
 615
 616/*
 617 * free a contiguous series of pages
 618 */
 619static void free_page_series(unsigned long from, unsigned long to)
 620{
 621        for (; from < to; from += PAGE_SIZE) {
 622                struct page *page = virt_to_page(from);
 623
 624                kdebug("- free %lx", from);
 625                atomic_long_dec(&mmap_pages_allocated);
 626                if (page_count(page) != 1)
 627                        kdebug("free page %p: refcount not one: %d",
 628                               page, page_count(page));
 629                put_page(page);
 630        }
 631}
 632
 633/*
 634 * release a reference to a region
 635 * - the caller must hold the region semaphore for writing, which this releases
 636 * - the region may not have been added to the tree yet, in which case vm_top
 637 *   will equal vm_start
 638 */
 639static void __put_nommu_region(struct vm_region *region)
 640        __releases(nommu_region_sem)
 641{
 642        kenter("%p{%d}", region, region->vm_usage);
 643
 644        BUG_ON(!nommu_region_tree.rb_node);
 645
 646        if (--region->vm_usage == 0) {
 647                if (region->vm_top > region->vm_start)
 648                        delete_nommu_region(region);
 649                up_write(&nommu_region_sem);
 650
 651                if (region->vm_file)
 652                        fput(region->vm_file);
 653
 654                /* IO memory and memory shared directly out of the pagecache
 655                 * from ramfs/tmpfs mustn't be released here */
 656                if (region->vm_flags & VM_MAPPED_COPY) {
 657                        kdebug("free series");
 658                        free_page_series(region->vm_start, region->vm_top);
 659                }
 660                kmem_cache_free(vm_region_jar, region);
 661        } else {
 662                up_write(&nommu_region_sem);
 663        }
 664}
 665
 666/*
 667 * release a reference to a region
 668 */
 669static void put_nommu_region(struct vm_region *region)
 670{
 671        down_write(&nommu_region_sem);
 672        __put_nommu_region(region);
 673}
 674
 675/*
 676 * update protection on a vma
 677 */
 678static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
 679{
 680#ifdef CONFIG_MPU
 681        struct mm_struct *mm = vma->vm_mm;
 682        long start = vma->vm_start & PAGE_MASK;
 683        while (start < vma->vm_end) {
 684                protect_page(mm, start, flags);
 685                start += PAGE_SIZE;
 686        }
 687        update_protections(mm);
 688#endif
 689}
 690
 691/*
 692 * add a VMA into a process's mm_struct in the appropriate place in the list
 693 * and tree and add to the address space's page tree also if not an anonymous
 694 * page
 695 * - should be called with mm->mmap_sem held writelocked
 696 */
 697static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 698{
 699        struct vm_area_struct *pvma, *prev;
 700        struct address_space *mapping;
 701        struct rb_node **p, *parent, *rb_prev;
 702
 703        kenter(",%p", vma);
 704
 705        BUG_ON(!vma->vm_region);
 706
 707        mm->map_count++;
 708        vma->vm_mm = mm;
 709
 710        protect_vma(vma, vma->vm_flags);
 711
 712        /* add the VMA to the mapping */
 713        if (vma->vm_file) {
 714                mapping = vma->vm_file->f_mapping;
 715
 716                mutex_lock(&mapping->i_mmap_mutex);
 717                flush_dcache_mmap_lock(mapping);
 718                vma_interval_tree_insert(vma, &mapping->i_mmap);
 719                flush_dcache_mmap_unlock(mapping);
 720                mutex_unlock(&mapping->i_mmap_mutex);
 721        }
 722
 723        /* add the VMA to the tree */
 724        parent = rb_prev = NULL;
 725        p = &mm->mm_rb.rb_node;
 726        while (*p) {
 727                parent = *p;
 728                pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 729
 730                /* sort by: start addr, end addr, VMA struct addr in that order
 731                 * (the latter is necessary as we may get identical VMAs) */
 732                if (vma->vm_start < pvma->vm_start)
 733                        p = &(*p)->rb_left;
 734                else if (vma->vm_start > pvma->vm_start) {
 735                        rb_prev = parent;
 736                        p = &(*p)->rb_right;
 737                } else if (vma->vm_end < pvma->vm_end)
 738                        p = &(*p)->rb_left;
 739                else if (vma->vm_end > pvma->vm_end) {
 740                        rb_prev = parent;
 741                        p = &(*p)->rb_right;
 742                } else if (vma < pvma)
 743                        p = &(*p)->rb_left;
 744                else if (vma > pvma) {
 745                        rb_prev = parent;
 746                        p = &(*p)->rb_right;
 747                } else
 748                        BUG();
 749        }
 750
 751        rb_link_node(&vma->vm_rb, parent, p);
 752        rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 753
 754        /* add VMA to the VMA list also */
 755        prev = NULL;
 756        if (rb_prev)
 757                prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 758
 759        __vma_link_list(mm, vma, prev, parent);
 760}
 761
 762/*
 763 * delete a VMA from its owning mm_struct and address space
 764 */
 765static void delete_vma_from_mm(struct vm_area_struct *vma)
 766{
 767        struct address_space *mapping;
 768        struct mm_struct *mm = vma->vm_mm;
 769
 770        kenter("%p", vma);
 771
 772        protect_vma(vma, 0);
 773
 774        mm->map_count--;
 775        if (mm->mmap_cache == vma)
 776                mm->mmap_cache = NULL;
 777
 778        /* remove the VMA from the mapping */
 779        if (vma->vm_file) {
 780                mapping = vma->vm_file->f_mapping;
 781
 782                mutex_lock(&mapping->i_mmap_mutex);
 783                flush_dcache_mmap_lock(mapping);
 784                vma_interval_tree_remove(vma, &mapping->i_mmap);
 785                flush_dcache_mmap_unlock(mapping);
 786                mutex_unlock(&mapping->i_mmap_mutex);
 787        }
 788
 789        /* remove from the MM's tree and list */
 790        rb_erase(&vma->vm_rb, &mm->mm_rb);
 791
 792        if (vma->vm_prev)
 793                vma->vm_prev->vm_next = vma->vm_next;
 794        else
 795                mm->mmap = vma->vm_next;
 796
 797        if (vma->vm_next)
 798                vma->vm_next->vm_prev = vma->vm_prev;
 799}
 800
 801/*
 802 * destroy a VMA record
 803 */
 804static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 805{
 806        kenter("%p", vma);
 807        if (vma->vm_ops && vma->vm_ops->close)
 808                vma->vm_ops->close(vma);
 809        if (vma->vm_file)
 810                fput(vma->vm_file);
 811        put_nommu_region(vma->vm_region);
 812        kmem_cache_free(vm_area_cachep, vma);
 813}
 814
 815/*
 816 * look up the first VMA in which addr resides, NULL if none
 817 * - should be called with mm->mmap_sem at least held readlocked
 818 */
 819struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 820{
 821        struct vm_area_struct *vma;
 822
 823        /* check the cache first */
 824        vma = ACCESS_ONCE(mm->mmap_cache);
 825        if (vma && vma->vm_start <= addr && vma->vm_end > addr)
 826                return vma;
 827
 828        /* trawl the list (there may be multiple mappings in which addr
 829         * resides) */
 830        for (vma = mm->mmap; vma; vma = vma->vm_next) {
 831                if (vma->vm_start > addr)
 832                        return NULL;
 833                if (vma->vm_end > addr) {
 834                        mm->mmap_cache = vma;
 835                        return vma;
 836                }
 837        }
 838
 839        return NULL;
 840}
 841EXPORT_SYMBOL(find_vma);
 842
 843/*
 844 * find a VMA
 845 * - we don't extend stack VMAs under NOMMU conditions
 846 */
 847struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 848{
 849        return find_vma(mm, addr);
 850}
 851
 852/*
 853 * expand a stack to a given address
 854 * - not supported under NOMMU conditions
 855 */
 856int expand_stack(struct vm_area_struct *vma, unsigned long address)
 857{
 858        return -ENOMEM;
 859}
 860
 861/*
 862 * look up the first VMA exactly that exactly matches addr
 863 * - should be called with mm->mmap_sem at least held readlocked
 864 */
 865static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 866                                             unsigned long addr,
 867                                             unsigned long len)
 868{
 869        struct vm_area_struct *vma;
 870        unsigned long end = addr + len;
 871
 872        /* check the cache first */
 873        vma = mm->mmap_cache;
 874        if (vma && vma->vm_start == addr && vma->vm_end == end)
 875                return vma;
 876
 877        /* trawl the list (there may be multiple mappings in which addr
 878         * resides) */
 879        for (vma = mm->mmap; vma; vma = vma->vm_next) {
 880                if (vma->vm_start < addr)
 881                        continue;
 882                if (vma->vm_start > addr)
 883                        return NULL;
 884                if (vma->vm_end == end) {
 885                        mm->mmap_cache = vma;
 886                        return vma;
 887                }
 888        }
 889
 890        return NULL;
 891}
 892
 893/*
 894 * determine whether a mapping should be permitted and, if so, what sort of
 895 * mapping we're capable of supporting
 896 */
 897static int validate_mmap_request(struct file *file,
 898                                 unsigned long addr,
 899                                 unsigned long len,
 900                                 unsigned long prot,
 901                                 unsigned long flags,
 902                                 unsigned long pgoff,
 903                                 unsigned long *_capabilities)
 904{
 905        unsigned long capabilities, rlen;
 906        int ret;
 907
 908        /* do the simple checks first */
 909        if (flags & MAP_FIXED) {
 910                printk(KERN_DEBUG
 911                       "%d: Can't do fixed-address/overlay mmap of RAM\n",
 912                       current->pid);
 913                return -EINVAL;
 914        }
 915
 916        if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 917            (flags & MAP_TYPE) != MAP_SHARED)
 918                return -EINVAL;
 919
 920        if (!len)
 921                return -EINVAL;
 922
 923        /* Careful about overflows.. */
 924        rlen = PAGE_ALIGN(len);
 925        if (!rlen || rlen > TASK_SIZE)
 926                return -ENOMEM;
 927
 928        /* offset overflow? */
 929        if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
 930                return -EOVERFLOW;
 931
 932        if (file) {
 933                /* validate file mapping requests */
 934                struct address_space *mapping;
 935
 936                /* files must support mmap */
 937                if (!file->f_op || !file->f_op->mmap)
 938                        return -ENODEV;
 939
 940                /* work out if what we've got could possibly be shared
 941                 * - we support chardevs that provide their own "memory"
 942                 * - we support files/blockdevs that are memory backed
 943                 */
 944                mapping = file->f_mapping;
 945                if (!mapping)
 946                        mapping = file_inode(file)->i_mapping;
 947
 948                capabilities = 0;
 949                if (mapping && mapping->backing_dev_info)
 950                        capabilities = mapping->backing_dev_info->capabilities;
 951
 952                if (!capabilities) {
 953                        /* no explicit capabilities set, so assume some
 954                         * defaults */
 955                        switch (file_inode(file)->i_mode & S_IFMT) {
 956                        case S_IFREG:
 957                        case S_IFBLK:
 958                                capabilities = BDI_CAP_MAP_COPY;
 959                                break;
 960
 961                        case S_IFCHR:
 962                                capabilities =
 963                                        BDI_CAP_MAP_DIRECT |
 964                                        BDI_CAP_READ_MAP |
 965                                        BDI_CAP_WRITE_MAP;
 966                                break;
 967
 968                        default:
 969                                return -EINVAL;
 970                        }
 971                }
 972
 973                /* eliminate any capabilities that we can't support on this
 974                 * device */
 975                if (!file->f_op->get_unmapped_area)
 976                        capabilities &= ~BDI_CAP_MAP_DIRECT;
 977                if (!file->f_op->read)
 978                        capabilities &= ~BDI_CAP_MAP_COPY;
 979
 980                /* The file shall have been opened with read permission. */
 981                if (!(file->f_mode & FMODE_READ))
 982                        return -EACCES;
 983
 984                if (flags & MAP_SHARED) {
 985                        /* do checks for writing, appending and locking */
 986                        if ((prot & PROT_WRITE) &&
 987                            !(file->f_mode & FMODE_WRITE))
 988                                return -EACCES;
 989
 990                        if (IS_APPEND(file_inode(file)) &&
 991                            (file->f_mode & FMODE_WRITE))
 992                                return -EACCES;
 993
 994                        if (locks_verify_locked(file_inode(file)))
 995                                return -EAGAIN;
 996
 997                        if (!(capabilities & BDI_CAP_MAP_DIRECT))
 998                                return -ENODEV;
 999
1000                        /* we mustn't privatise shared mappings */
1001                        capabilities &= ~BDI_CAP_MAP_COPY;
1002                }
1003                else {
1004                        /* we're going to read the file into private memory we
1005                         * allocate */
1006                        if (!(capabilities & BDI_CAP_MAP_COPY))
1007                                return -ENODEV;
1008
1009                        /* we don't permit a private writable mapping to be
1010                         * shared with the backing device */
1011                        if (prot & PROT_WRITE)
1012                                capabilities &= ~BDI_CAP_MAP_DIRECT;
1013                }
1014
1015                if (capabilities & BDI_CAP_MAP_DIRECT) {
1016                        if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
1017                            ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1018                            ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
1019                            ) {
1020                                capabilities &= ~BDI_CAP_MAP_DIRECT;
1021                                if (flags & MAP_SHARED) {
1022                                        printk(KERN_WARNING
1023                                               "MAP_SHARED not completely supported on !MMU\n");
1024                                        return -EINVAL;
1025                                }
1026                        }
1027                }
1028
1029                /* handle executable mappings and implied executable
1030                 * mappings */
1031                if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1032                        if (prot & PROT_EXEC)
1033                                return -EPERM;
1034                }
1035                else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1036                        /* handle implication of PROT_EXEC by PROT_READ */
1037                        if (current->personality & READ_IMPLIES_EXEC) {
1038                                if (capabilities & BDI_CAP_EXEC_MAP)
1039                                        prot |= PROT_EXEC;
1040                        }
1041                }
1042                else if ((prot & PROT_READ) &&
1043                         (prot & PROT_EXEC) &&
1044                         !(capabilities & BDI_CAP_EXEC_MAP)
1045                         ) {
1046                        /* backing file is not executable, try to copy */
1047                        capabilities &= ~BDI_CAP_MAP_DIRECT;
1048                }
1049        }
1050        else {
1051                /* anonymous mappings are always memory backed and can be
1052                 * privately mapped
1053                 */
1054                capabilities = BDI_CAP_MAP_COPY;
1055
1056                /* handle PROT_EXEC implication by PROT_READ */
1057                if ((prot & PROT_READ) &&
1058                    (current->personality & READ_IMPLIES_EXEC))
1059                        prot |= PROT_EXEC;
1060        }
1061
1062        /* allow the security API to have its say */
1063        ret = security_mmap_addr(addr);
1064        if (ret < 0)
1065                return ret;
1066
1067        /* looks okay */
1068        *_capabilities = capabilities;
1069        return 0;
1070}
1071
1072/*
1073 * we've determined that we can make the mapping, now translate what we
1074 * now know into VMA flags
1075 */
1076static unsigned long determine_vm_flags(struct file *file,
1077                                        unsigned long prot,
1078                                        unsigned long flags,
1079                                        unsigned long capabilities)
1080{
1081        unsigned long vm_flags;
1082
1083        vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1084        /* vm_flags |= mm->def_flags; */
1085
1086        if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1087                /* attempt to share read-only copies of mapped file chunks */
1088                vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1089                if (file && !(prot & PROT_WRITE))
1090                        vm_flags |= VM_MAYSHARE;
1091        } else {
1092                /* overlay a shareable mapping on the backing device or inode
1093                 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1094                 * romfs/cramfs */
1095                vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1096                if (flags & MAP_SHARED)
1097                        vm_flags |= VM_SHARED;
1098        }
1099
1100        /* refuse to let anyone share private mappings with this process if
1101         * it's being traced - otherwise breakpoints set in it may interfere
1102         * with another untraced process
1103         */
1104        if ((flags & MAP_PRIVATE) && current->ptrace)
1105                vm_flags &= ~VM_MAYSHARE;
1106
1107        return vm_flags;
1108}
1109
1110/*
1111 * set up a shared mapping on a file (the driver or filesystem provides and
1112 * pins the storage)
1113 */
1114static int do_mmap_shared_file(struct vm_area_struct *vma)
1115{
1116        int ret;
1117
1118        ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1119        if (ret == 0) {
1120                vma->vm_region->vm_top = vma->vm_region->vm_end;
1121                return 0;
1122        }
1123        if (ret != -ENOSYS)
1124                return ret;
1125
1126        /* getting -ENOSYS indicates that direct mmap isn't possible (as
1127         * opposed to tried but failed) so we can only give a suitable error as
1128         * it's not possible to make a private copy if MAP_SHARED was given */
1129        return -ENODEV;
1130}
1131
1132/*
1133 * set up a private mapping or an anonymous shared mapping
1134 */
1135static int do_mmap_private(struct vm_area_struct *vma,
1136                           struct vm_region *region,
1137                           unsigned long len,
1138                           unsigned long capabilities)
1139{
1140        struct page *pages;
1141        unsigned long total, point, n;
1142        void *base;
1143        int ret, order;
1144
1145        /* invoke the file's mapping function so that it can keep track of
1146         * shared mappings on devices or memory
1147         * - VM_MAYSHARE will be set if it may attempt to share
1148         */
1149        if (capabilities & BDI_CAP_MAP_DIRECT) {
1150                ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1151                if (ret == 0) {
1152                        /* shouldn't return success if we're not sharing */
1153                        BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1154                        vma->vm_region->vm_top = vma->vm_region->vm_end;
1155                        return 0;
1156                }
1157                if (ret != -ENOSYS)
1158                        return ret;
1159
1160                /* getting an ENOSYS error indicates that direct mmap isn't
1161                 * possible (as opposed to tried but failed) so we'll try to
1162                 * make a private copy of the data and map that instead */
1163        }
1164
1165
1166        /* allocate some memory to hold the mapping
1167         * - note that this may not return a page-aligned address if the object
1168         *   we're allocating is smaller than a page
1169         */
1170        order = get_order(len);
1171        kdebug("alloc order %d for %lx", order, len);
1172
1173        pages = alloc_pages(GFP_KERNEL, order);
1174        if (!pages)
1175                goto enomem;
1176
1177        total = 1 << order;
1178        atomic_long_add(total, &mmap_pages_allocated);
1179
1180        point = len >> PAGE_SHIFT;
1181
1182        /* we allocated a power-of-2 sized page set, so we may want to trim off
1183         * the excess */
1184        if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1185                while (total > point) {
1186                        order = ilog2(total - point);
1187                        n = 1 << order;
1188                        kdebug("shave %lu/%lu @%lu", n, total - point, total);
1189                        atomic_long_sub(n, &mmap_pages_allocated);
1190                        total -= n;
1191                        set_page_refcounted(pages + total);
1192                        __free_pages(pages + total, order);
1193                }
1194        }
1195
1196        for (point = 1; point < total; point++)
1197                set_page_refcounted(&pages[point]);
1198
1199        base = page_address(pages);
1200        region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1201        region->vm_start = (unsigned long) base;
1202        region->vm_end   = region->vm_start + len;
1203        region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1204
1205        vma->vm_start = region->vm_start;
1206        vma->vm_end   = region->vm_start + len;
1207
1208        if (vma->vm_file) {
1209                /* read the contents of a file into the copy */
1210                mm_segment_t old_fs;
1211                loff_t fpos;
1212
1213                fpos = vma->vm_pgoff;
1214                fpos <<= PAGE_SHIFT;
1215
1216                old_fs = get_fs();
1217                set_fs(KERNEL_DS);
1218                ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1219                set_fs(old_fs);
1220
1221                if (ret < 0)
1222                        goto error_free;
1223
1224                /* clear the last little bit */
1225                if (ret < len)
1226                        memset(base + ret, 0, len - ret);
1227
1228        }
1229
1230        return 0;
1231
1232error_free:
1233        free_page_series(region->vm_start, region->vm_top);
1234        region->vm_start = vma->vm_start = 0;
1235        region->vm_end   = vma->vm_end = 0;
1236        region->vm_top   = 0;
1237        return ret;
1238
1239enomem:
1240        printk("Allocation of length %lu from process %d (%s) failed\n",
1241               len, current->pid, current->comm);
1242        show_free_areas(0);
1243        return -ENOMEM;
1244}
1245
1246/*
1247 * handle mapping creation for uClinux
1248 */
1249unsigned long do_mmap_pgoff(struct file *file,
1250                            unsigned long addr,
1251                            unsigned long len,
1252                            unsigned long prot,
1253                            unsigned long flags,
1254                            unsigned long pgoff,
1255                            unsigned long *populate)
1256{
1257        struct vm_area_struct *vma;
1258        struct vm_region *region;
1259        struct rb_node *rb;
1260        unsigned long capabilities, vm_flags, result;
1261        int ret;
1262
1263        kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1264
1265        *populate = 0;
1266
1267        /* decide whether we should attempt the mapping, and if so what sort of
1268         * mapping */
1269        ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1270                                    &capabilities);
1271        if (ret < 0) {
1272                kleave(" = %d [val]", ret);
1273                return ret;
1274        }
1275
1276        /* we ignore the address hint */
1277        addr = 0;
1278        len = PAGE_ALIGN(len);
1279
1280        /* we've determined that we can make the mapping, now translate what we
1281         * now know into VMA flags */
1282        vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1283
1284        /* we're going to need to record the mapping */
1285        region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1286        if (!region)
1287                goto error_getting_region;
1288
1289        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1290        if (!vma)
1291                goto error_getting_vma;
1292
1293        region->vm_usage = 1;
1294        region->vm_flags = vm_flags;
1295        region->vm_pgoff = pgoff;
1296
1297        INIT_LIST_HEAD(&vma->anon_vma_chain);
1298        vma->vm_flags = vm_flags;
1299        vma->vm_pgoff = pgoff;
1300
1301        if (file) {
1302                region->vm_file = get_file(file);
1303                vma->vm_file = get_file(file);
1304        }
1305
1306        down_write(&nommu_region_sem);
1307
1308        /* if we want to share, we need to check for regions created by other
1309         * mmap() calls that overlap with our proposed mapping
1310         * - we can only share with a superset match on most regular files
1311         * - shared mappings on character devices and memory backed files are
1312         *   permitted to overlap inexactly as far as we are concerned for in
1313         *   these cases, sharing is handled in the driver or filesystem rather
1314         *   than here
1315         */
1316        if (vm_flags & VM_MAYSHARE) {
1317                struct vm_region *pregion;
1318                unsigned long pglen, rpglen, pgend, rpgend, start;
1319
1320                pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1321                pgend = pgoff + pglen;
1322
1323                for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1324                        pregion = rb_entry(rb, struct vm_region, vm_rb);
1325
1326                        if (!(pregion->vm_flags & VM_MAYSHARE))
1327                                continue;
1328
1329                        /* search for overlapping mappings on the same file */
1330                        if (file_inode(pregion->vm_file) !=
1331                            file_inode(file))
1332                                continue;
1333
1334                        if (pregion->vm_pgoff >= pgend)
1335                                continue;
1336
1337                        rpglen = pregion->vm_end - pregion->vm_start;
1338                        rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1339                        rpgend = pregion->vm_pgoff + rpglen;
1340                        if (pgoff >= rpgend)
1341                                continue;
1342
1343                        /* handle inexactly overlapping matches between
1344                         * mappings */
1345                        if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1346                            !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1347                                /* new mapping is not a subset of the region */
1348                                if (!(capabilities & BDI_CAP_MAP_DIRECT))
1349                                        goto sharing_violation;
1350                                continue;
1351                        }
1352
1353                        /* we've found a region we can share */
1354                        pregion->vm_usage++;
1355                        vma->vm_region = pregion;
1356                        start = pregion->vm_start;
1357                        start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1358                        vma->vm_start = start;
1359                        vma->vm_end = start + len;
1360
1361                        if (pregion->vm_flags & VM_MAPPED_COPY) {
1362                                kdebug("share copy");
1363                                vma->vm_flags |= VM_MAPPED_COPY;
1364                        } else {
1365                                kdebug("share mmap");
1366                                ret = do_mmap_shared_file(vma);
1367                                if (ret < 0) {
1368                                        vma->vm_region = NULL;
1369                                        vma->vm_start = 0;
1370                                        vma->vm_end = 0;
1371                                        pregion->vm_usage--;
1372                                        pregion = NULL;
1373                                        goto error_just_free;
1374                                }
1375                        }
1376                        fput(region->vm_file);
1377                        kmem_cache_free(vm_region_jar, region);
1378                        region = pregion;
1379                        result = start;
1380                        goto share;
1381                }
1382
1383                /* obtain the address at which to make a shared mapping
1384                 * - this is the hook for quasi-memory character devices to
1385                 *   tell us the location of a shared mapping
1386                 */
1387                if (capabilities & BDI_CAP_MAP_DIRECT) {
1388                        addr = file->f_op->get_unmapped_area(file, addr, len,
1389                                                             pgoff, flags);
1390                        if (IS_ERR_VALUE(addr)) {
1391                                ret = addr;
1392                                if (ret != -ENOSYS)
1393                                        goto error_just_free;
1394
1395                                /* the driver refused to tell us where to site
1396                                 * the mapping so we'll have to attempt to copy
1397                                 * it */
1398                                ret = -ENODEV;
1399                                if (!(capabilities & BDI_CAP_MAP_COPY))
1400                                        goto error_just_free;
1401
1402                                capabilities &= ~BDI_CAP_MAP_DIRECT;
1403                        } else {
1404                                vma->vm_start = region->vm_start = addr;
1405                                vma->vm_end = region->vm_end = addr + len;
1406                        }
1407                }
1408        }
1409
1410        vma->vm_region = region;
1411
1412        /* set up the mapping
1413         * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1414         */
1415        if (file && vma->vm_flags & VM_SHARED)
1416                ret = do_mmap_shared_file(vma);
1417        else
1418                ret = do_mmap_private(vma, region, len, capabilities);
1419        if (ret < 0)
1420                goto error_just_free;
1421        add_nommu_region(region);
1422
1423        /* clear anonymous mappings that don't ask for uninitialized data */
1424        if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1425                memset((void *)region->vm_start, 0,
1426                       region->vm_end - region->vm_start);
1427
1428        /* okay... we have a mapping; now we have to register it */
1429        result = vma->vm_start;
1430
1431        current->mm->total_vm += len >> PAGE_SHIFT;
1432
1433share:
1434        add_vma_to_mm(current->mm, vma);
1435
1436        /* we flush the region from the icache only when the first executable
1437         * mapping of it is made  */
1438        if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1439                flush_icache_range(region->vm_start, region->vm_end);
1440                region->vm_icache_flushed = true;
1441        }
1442
1443        up_write(&nommu_region_sem);
1444
1445        kleave(" = %lx", result);
1446        return result;
1447
1448error_just_free:
1449        up_write(&nommu_region_sem);
1450error:
1451        if (region->vm_file)
1452                fput(region->vm_file);
1453        kmem_cache_free(vm_region_jar, region);
1454        if (vma->vm_file)
1455                fput(vma->vm_file);
1456        kmem_cache_free(vm_area_cachep, vma);
1457        kleave(" = %d", ret);
1458        return ret;
1459
1460sharing_violation:
1461        up_write(&nommu_region_sem);
1462        printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1463        ret = -EINVAL;
1464        goto error;
1465
1466error_getting_vma:
1467        kmem_cache_free(vm_region_jar, region);
1468        printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1469               " from process %d failed\n",
1470               len, current->pid);
1471        show_free_areas(0);
1472        return -ENOMEM;
1473
1474error_getting_region:
1475        printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1476               " from process %d failed\n",
1477               len, current->pid);
1478        show_free_areas(0);
1479        return -ENOMEM;
1480}
1481
1482SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1483                unsigned long, prot, unsigned long, flags,
1484                unsigned long, fd, unsigned long, pgoff)
1485{
1486        struct file *file = NULL;
1487        unsigned long retval = -EBADF;
1488
1489        audit_mmap_fd(fd, flags);
1490        if (!(flags & MAP_ANONYMOUS)) {
1491                file = fget(fd);
1492                if (!file)
1493                        goto out;
1494        }
1495
1496        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1497
1498        retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1499
1500        if (file)
1501                fput(file);
1502out:
1503        return retval;
1504}
1505
1506#ifdef __ARCH_WANT_SYS_OLD_MMAP
1507struct mmap_arg_struct {
1508        unsigned long addr;
1509        unsigned long len;
1510        unsigned long prot;
1511        unsigned long flags;
1512        unsigned long fd;
1513        unsigned long offset;
1514};
1515
1516SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1517{
1518        struct mmap_arg_struct a;
1519
1520        if (copy_from_user(&a, arg, sizeof(a)))
1521                return -EFAULT;
1522        if (a.offset & ~PAGE_MASK)
1523                return -EINVAL;
1524
1525        return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1526                              a.offset >> PAGE_SHIFT);
1527}
1528#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1529
1530/*
1531 * split a vma into two pieces at address 'addr', a new vma is allocated either
1532 * for the first part or the tail.
1533 */
1534int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1535              unsigned long addr, int new_below)
1536{
1537        struct vm_area_struct *new;
1538        struct vm_region *region;
1539        unsigned long npages;
1540
1541        kenter("");
1542
1543        /* we're only permitted to split anonymous regions (these should have
1544         * only a single usage on the region) */
1545        if (vma->vm_file)
1546                return -ENOMEM;
1547
1548        if (mm->map_count >= sysctl_max_map_count)
1549                return -ENOMEM;
1550
1551        region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1552        if (!region)
1553                return -ENOMEM;
1554
1555        new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1556        if (!new) {
1557                kmem_cache_free(vm_region_jar, region);
1558                return -ENOMEM;
1559        }
1560
1561        /* most fields are the same, copy all, and then fixup */
1562        *new = *vma;
1563        *region = *vma->vm_region;
1564        new->vm_region = region;
1565
1566        npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1567
1568        if (new_below) {
1569                region->vm_top = region->vm_end = new->vm_end = addr;
1570        } else {
1571                region->vm_start = new->vm_start = addr;
1572                region->vm_pgoff = new->vm_pgoff += npages;
1573        }
1574
1575        if (new->vm_ops && new->vm_ops->open)
1576                new->vm_ops->open(new);
1577
1578        delete_vma_from_mm(vma);
1579        down_write(&nommu_region_sem);
1580        delete_nommu_region(vma->vm_region);
1581        if (new_below) {
1582                vma->vm_region->vm_start = vma->vm_start = addr;
1583                vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1584        } else {
1585                vma->vm_region->vm_end = vma->vm_end = addr;
1586                vma->vm_region->vm_top = addr;
1587        }
1588        add_nommu_region(vma->vm_region);
1589        add_nommu_region(new->vm_region);
1590        up_write(&nommu_region_sem);
1591        add_vma_to_mm(mm, vma);
1592        add_vma_to_mm(mm, new);
1593        return 0;
1594}
1595
1596/*
1597 * shrink a VMA by removing the specified chunk from either the beginning or
1598 * the end
1599 */
1600static int shrink_vma(struct mm_struct *mm,
1601                      struct vm_area_struct *vma,
1602                      unsigned long from, unsigned long to)
1603{
1604        struct vm_region *region;
1605
1606        kenter("");
1607
1608        /* adjust the VMA's pointers, which may reposition it in the MM's tree
1609         * and list */
1610        delete_vma_from_mm(vma);
1611        if (from > vma->vm_start)
1612                vma->vm_end = from;
1613        else
1614                vma->vm_start = to;
1615        add_vma_to_mm(mm, vma);
1616
1617        /* cut the backing region down to size */
1618        region = vma->vm_region;
1619        BUG_ON(region->vm_usage != 1);
1620
1621        down_write(&nommu_region_sem);
1622        delete_nommu_region(region);
1623        if (from > region->vm_start) {
1624                to = region->vm_top;
1625                region->vm_top = region->vm_end = from;
1626        } else {
1627                region->vm_start = to;
1628        }
1629        add_nommu_region(region);
1630        up_write(&nommu_region_sem);
1631
1632        free_page_series(from, to);
1633        return 0;
1634}
1635
1636/*
1637 * release a mapping
1638 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1639 *   VMA, though it need not cover the whole VMA
1640 */
1641int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1642{
1643        struct vm_area_struct *vma;
1644        unsigned long end;
1645        int ret;
1646
1647        kenter(",%lx,%zx", start, len);
1648
1649        len = PAGE_ALIGN(len);
1650        if (len == 0)
1651                return -EINVAL;
1652
1653        end = start + len;
1654
1655        /* find the first potentially overlapping VMA */
1656        vma = find_vma(mm, start);
1657        if (!vma) {
1658                static int limit = 0;
1659                if (limit < 5) {
1660                        printk(KERN_WARNING
1661                               "munmap of memory not mmapped by process %d"
1662                               " (%s): 0x%lx-0x%lx\n",
1663                               current->pid, current->comm,
1664                               start, start + len - 1);
1665                        limit++;
1666                }
1667                return -EINVAL;
1668        }
1669
1670        /* we're allowed to split an anonymous VMA but not a file-backed one */
1671        if (vma->vm_file) {
1672                do {
1673                        if (start > vma->vm_start) {
1674                                kleave(" = -EINVAL [miss]");
1675                                return -EINVAL;
1676                        }
1677                        if (end == vma->vm_end)
1678                                goto erase_whole_vma;
1679                        vma = vma->vm_next;
1680                } while (vma);
1681                kleave(" = -EINVAL [split file]");
1682                return -EINVAL;
1683        } else {
1684                /* the chunk must be a subset of the VMA found */
1685                if (start == vma->vm_start && end == vma->vm_end)
1686                        goto erase_whole_vma;
1687                if (start < vma->vm_start || end > vma->vm_end) {
1688                        kleave(" = -EINVAL [superset]");
1689                        return -EINVAL;
1690                }
1691                if (start & ~PAGE_MASK) {
1692                        kleave(" = -EINVAL [unaligned start]");
1693                        return -EINVAL;
1694                }
1695                if (end != vma->vm_end && end & ~PAGE_MASK) {
1696                        kleave(" = -EINVAL [unaligned split]");
1697                        return -EINVAL;
1698                }
1699                if (start != vma->vm_start && end != vma->vm_end) {
1700                        ret = split_vma(mm, vma, start, 1);
1701                        if (ret < 0) {
1702                                kleave(" = %d [split]", ret);
1703                                return ret;
1704                        }
1705                }
1706                return shrink_vma(mm, vma, start, end);
1707        }
1708
1709erase_whole_vma:
1710        delete_vma_from_mm(vma);
1711        delete_vma(mm, vma);
1712        kleave(" = 0");
1713        return 0;
1714}
1715EXPORT_SYMBOL(do_munmap);
1716
1717int vm_munmap(unsigned long addr, size_t len)
1718{
1719        struct mm_struct *mm = current->mm;
1720        int ret;
1721
1722        down_write(&mm->mmap_sem);
1723        ret = do_munmap(mm, addr, len);
1724        up_write(&mm->mmap_sem);
1725        return ret;
1726}
1727EXPORT_SYMBOL(vm_munmap);
1728
1729SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1730{
1731        return vm_munmap(addr, len);
1732}
1733
1734/*
1735 * release all the mappings made in a process's VM space
1736 */
1737void exit_mmap(struct mm_struct *mm)
1738{
1739        struct vm_area_struct *vma;
1740
1741        if (!mm)
1742                return;
1743
1744        kenter("");
1745
1746        mm->total_vm = 0;
1747
1748        while ((vma = mm->mmap)) {
1749                mm->mmap = vma->vm_next;
1750                delete_vma_from_mm(vma);
1751                delete_vma(mm, vma);
1752                cond_resched();
1753        }
1754
1755        kleave("");
1756}
1757
1758unsigned long vm_brk(unsigned long addr, unsigned long len)
1759{
1760        return -ENOMEM;
1761}
1762
1763/*
1764 * expand (or shrink) an existing mapping, potentially moving it at the same
1765 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1766 *
1767 * under NOMMU conditions, we only permit changing a mapping's size, and only
1768 * as long as it stays within the region allocated by do_mmap_private() and the
1769 * block is not shareable
1770 *
1771 * MREMAP_FIXED is not supported under NOMMU conditions
1772 */
1773unsigned long do_mremap(unsigned long addr,
1774                        unsigned long old_len, unsigned long new_len,
1775                        unsigned long flags, unsigned long new_addr)
1776{
1777        struct vm_area_struct *vma;
1778
1779        /* insanity checks first */
1780        old_len = PAGE_ALIGN(old_len);
1781        new_len = PAGE_ALIGN(new_len);
1782        if (old_len == 0 || new_len == 0)
1783                return (unsigned long) -EINVAL;
1784
1785        if (addr & ~PAGE_MASK)
1786                return -EINVAL;
1787
1788        if (flags & MREMAP_FIXED && new_addr != addr)
1789                return (unsigned long) -EINVAL;
1790
1791        vma = find_vma_exact(current->mm, addr, old_len);
1792        if (!vma)
1793                return (unsigned long) -EINVAL;
1794
1795        if (vma->vm_end != vma->vm_start + old_len)
1796                return (unsigned long) -EFAULT;
1797
1798        if (vma->vm_flags & VM_MAYSHARE)
1799                return (unsigned long) -EPERM;
1800
1801        if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1802                return (unsigned long) -ENOMEM;
1803
1804        /* all checks complete - do it */
1805        vma->vm_end = vma->vm_start + new_len;
1806        return vma->vm_start;
1807}
1808EXPORT_SYMBOL(do_mremap);
1809
1810SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1811                unsigned long, new_len, unsigned long, flags,
1812                unsigned long, new_addr)
1813{
1814        unsigned long ret;
1815
1816        down_write(&current->mm->mmap_sem);
1817        ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1818        up_write(&current->mm->mmap_sem);
1819        return ret;
1820}
1821
1822struct page *follow_page_mask(struct vm_area_struct *vma,
1823                              unsigned long address, unsigned int flags,
1824                              unsigned int *page_mask)
1825{
1826        *page_mask = 0;
1827        return NULL;
1828}
1829
1830int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1831                unsigned long pfn, unsigned long size, pgprot_t prot)
1832{
1833        if (addr != (pfn << PAGE_SHIFT))
1834                return -EINVAL;
1835
1836        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1837        return 0;
1838}
1839EXPORT_SYMBOL(remap_pfn_range);
1840
1841int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1842{
1843        unsigned long pfn = start >> PAGE_SHIFT;
1844        unsigned long vm_len = vma->vm_end - vma->vm_start;
1845
1846        pfn += vma->vm_pgoff;
1847        return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1848}
1849EXPORT_SYMBOL(vm_iomap_memory);
1850
1851int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1852                        unsigned long pgoff)
1853{
1854        unsigned int size = vma->vm_end - vma->vm_start;
1855
1856        if (!(vma->vm_flags & VM_USERMAP))
1857                return -EINVAL;
1858
1859        vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1860        vma->vm_end = vma->vm_start + size;
1861
1862        return 0;
1863}
1864EXPORT_SYMBOL(remap_vmalloc_range);
1865
1866unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1867        unsigned long len, unsigned long pgoff, unsigned long flags)
1868{
1869        return -ENOMEM;
1870}
1871
1872void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1873{
1874}
1875
1876void unmap_mapping_range(struct address_space *mapping,
1877                         loff_t const holebegin, loff_t const holelen,
1878                         int even_cows)
1879{
1880}
1881EXPORT_SYMBOL(unmap_mapping_range);
1882
1883/*
1884 * Check that a process has enough memory to allocate a new virtual
1885 * mapping. 0 means there is enough memory for the allocation to
1886 * succeed and -ENOMEM implies there is not.
1887 *
1888 * We currently support three overcommit policies, which are set via the
1889 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1890 *
1891 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1892 * Additional code 2002 Jul 20 by Robert Love.
1893 *
1894 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1895 *
1896 * Note this is a helper function intended to be used by LSMs which
1897 * wish to use this logic.
1898 */
1899int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1900{
1901        unsigned long free, allowed;
1902
1903        vm_acct_memory(pages);
1904
1905        /*
1906         * Sometimes we want to use more memory than we have
1907         */
1908        if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1909                return 0;
1910
1911        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1912                free = global_page_state(NR_FREE_PAGES);
1913                free += global_page_state(NR_FILE_PAGES);
1914
1915                /*
1916                 * shmem pages shouldn't be counted as free in this
1917                 * case, they can't be purged, only swapped out, and
1918                 * that won't affect the overall amount of available
1919                 * memory in the system.
1920                 */
1921                free -= global_page_state(NR_SHMEM);
1922
1923                free += get_nr_swap_pages();
1924
1925                /*
1926                 * Any slabs which are created with the
1927                 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1928                 * which are reclaimable, under pressure.  The dentry
1929                 * cache and most inode caches should fall into this
1930                 */
1931                free += global_page_state(NR_SLAB_RECLAIMABLE);
1932
1933                /*
1934                 * Leave reserved pages. The pages are not for anonymous pages.
1935                 */
1936                if (free <= totalreserve_pages)
1937                        goto error;
1938                else
1939                        free -= totalreserve_pages;
1940
1941                /*
1942                 * Leave the last 3% for root
1943                 */
1944                if (!cap_sys_admin)
1945                        free -= free / 32;
1946
1947                if (free > pages)
1948                        return 0;
1949
1950                goto error;
1951        }
1952
1953        allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1954        /*
1955         * Leave the last 3% for root
1956         */
1957        if (!cap_sys_admin)
1958                allowed -= allowed / 32;
1959        allowed += total_swap_pages;
1960
1961        /* Don't let a single process grow too big:
1962           leave 3% of the size of this process for other processes */
1963        if (mm)
1964                allowed -= mm->total_vm / 32;
1965
1966        if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1967                return 0;
1968
1969error:
1970        vm_unacct_memory(pages);
1971
1972        return -ENOMEM;
1973}
1974
1975int in_gate_area_no_mm(unsigned long addr)
1976{
1977        return 0;
1978}
1979
1980int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1981{
1982        BUG();
1983        return 0;
1984}
1985EXPORT_SYMBOL(filemap_fault);
1986
1987int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
1988                             unsigned long size, pgoff_t pgoff)
1989{
1990        BUG();
1991        return 0;
1992}
1993EXPORT_SYMBOL(generic_file_remap_pages);
1994
1995static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1996                unsigned long addr, void *buf, int len, int write)
1997{
1998        struct vm_area_struct *vma;
1999
2000        down_read(&mm->mmap_sem);
2001
2002        /* the access must start within one of the target process's mappings */
2003        vma = find_vma(mm, addr);
2004        if (vma) {
2005                /* don't overrun this mapping */
2006                if (addr + len >= vma->vm_end)
2007                        len = vma->vm_end - addr;
2008
2009                /* only read or write mappings where it is permitted */
2010                if (write && vma->vm_flags & VM_MAYWRITE)
2011                        copy_to_user_page(vma, NULL, addr,
2012                                         (void *) addr, buf, len);
2013                else if (!write && vma->vm_flags & VM_MAYREAD)
2014                        copy_from_user_page(vma, NULL, addr,
2015                                            buf, (void *) addr, len);
2016                else
2017                        len = 0;
2018        } else {
2019                len = 0;
2020        }
2021
2022        up_read(&mm->mmap_sem);
2023
2024        return len;
2025}
2026
2027/**
2028 * @access_remote_vm - access another process' address space
2029 * @mm:         the mm_struct of the target address space
2030 * @addr:       start address to access
2031 * @buf:        source or destination buffer
2032 * @len:        number of bytes to transfer
2033 * @write:      whether the access is a write
2034 *
2035 * The caller must hold a reference on @mm.
2036 */
2037int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2038                void *buf, int len, int write)
2039{
2040        return __access_remote_vm(NULL, mm, addr, buf, len, write);
2041}
2042
2043/*
2044 * Access another process' address space.
2045 * - source/target buffer must be kernel space
2046 */
2047int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2048{
2049        struct mm_struct *mm;
2050
2051        if (addr + len < addr)
2052                return 0;
2053
2054        mm = get_task_mm(tsk);
2055        if (!mm)
2056                return 0;
2057
2058        len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2059
2060        mmput(mm);
2061        return len;
2062}
2063
2064/**
2065 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2066 * @inode: The inode to check
2067 * @size: The current filesize of the inode
2068 * @newsize: The proposed filesize of the inode
2069 *
2070 * Check the shared mappings on an inode on behalf of a shrinking truncate to
2071 * make sure that that any outstanding VMAs aren't broken and then shrink the
2072 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2073 * automatically grant mappings that are too large.
2074 */
2075int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2076                                size_t newsize)
2077{
2078        struct vm_area_struct *vma;
2079        struct vm_region *region;
2080        pgoff_t low, high;
2081        size_t r_size, r_top;
2082
2083        low = newsize >> PAGE_SHIFT;
2084        high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2085
2086        down_write(&nommu_region_sem);
2087        mutex_lock(&inode->i_mapping->i_mmap_mutex);
2088
2089        /* search for VMAs that fall within the dead zone */
2090        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
2091                /* found one - only interested if it's shared out of the page
2092                 * cache */
2093                if (vma->vm_flags & VM_SHARED) {
2094                        mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2095                        up_write(&nommu_region_sem);
2096                        return -ETXTBSY; /* not quite true, but near enough */
2097                }
2098        }
2099
2100        /* reduce any regions that overlap the dead zone - if in existence,
2101         * these will be pointed to by VMAs that don't overlap the dead zone
2102         *
2103         * we don't check for any regions that start beyond the EOF as there
2104         * shouldn't be any
2105         */
2106        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
2107                                  0, ULONG_MAX) {
2108                if (!(vma->vm_flags & VM_SHARED))
2109                        continue;
2110
2111                region = vma->vm_region;
2112                r_size = region->vm_top - region->vm_start;
2113                r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2114
2115                if (r_top > newsize) {
2116                        region->vm_top -= r_top - newsize;
2117                        if (region->vm_end > region->vm_top)
2118                                region->vm_end = region->vm_top;
2119                }
2120        }
2121
2122        mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2123        up_write(&nommu_region_sem);
2124        return 0;
2125}
2126
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.