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 highest_memmap_pfn;
  60struct percpu_counter vm_committed_as;
  61int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  62int sysctl_overcommit_ratio = 50; /* default is 50% */
  63int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  64int sysctl_nr_trim_pages = CONFIG_NOMMU_INITIAL_TRIM_EXCESS;
  65unsigned long sysctl_user_reserve_kbytes __read_mostly = 1UL << 17; /* 128MB */
  66unsigned long sysctl_admin_reserve_kbytes __read_mostly = 1UL << 13; /* 8MB */
  67int heap_stack_gap = 0;
  68
  69atomic_long_t mmap_pages_allocated;
  70
  71/*
  72 * The global memory commitment made in the system can be a metric
  73 * that can be used to drive ballooning decisions when Linux is hosted
  74 * as a guest. On Hyper-V, the host implements a policy engine for dynamically
  75 * balancing memory across competing virtual machines that are hosted.
  76 * Several metrics drive this policy engine including the guest reported
  77 * memory commitment.
  78 */
  79unsigned long vm_memory_committed(void)
  80{
  81        return percpu_counter_read_positive(&vm_committed_as);
  82}
  83
  84EXPORT_SYMBOL_GPL(vm_memory_committed);
  85
  86EXPORT_SYMBOL(mem_map);
  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
 231LIST_HEAD(vmap_area_list);
 232
 233void vfree(const void *addr)
 234{
 235        kfree(addr);
 236}
 237EXPORT_SYMBOL(vfree);
 238
 239void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 240{
 241        /*
 242         *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 243         * returns only a logical address.
 244         */
 245        return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 246}
 247EXPORT_SYMBOL(__vmalloc);
 248
 249void *vmalloc_user(unsigned long size)
 250{
 251        void *ret;
 252
 253        ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 254                        PAGE_KERNEL);
 255        if (ret) {
 256                struct vm_area_struct *vma;
 257
 258                down_write(&current->mm->mmap_sem);
 259                vma = find_vma(current->mm, (unsigned long)ret);
 260                if (vma)
 261                        vma->vm_flags |= VM_USERMAP;
 262                up_write(&current->mm->mmap_sem);
 263        }
 264
 265        return ret;
 266}
 267EXPORT_SYMBOL(vmalloc_user);
 268
 269struct page *vmalloc_to_page(const void *addr)
 270{
 271        return virt_to_page(addr);
 272}
 273EXPORT_SYMBOL(vmalloc_to_page);
 274
 275unsigned long vmalloc_to_pfn(const void *addr)
 276{
 277        return page_to_pfn(virt_to_page(addr));
 278}
 279EXPORT_SYMBOL(vmalloc_to_pfn);
 280
 281long vread(char *buf, char *addr, unsigned long count)
 282{
 283        /* Don't allow overflow */
 284        if ((unsigned long) buf + count < count)
 285                count = -(unsigned long) buf;
 286
 287        memcpy(buf, addr, count);
 288        return count;
 289}
 290
 291long vwrite(char *buf, char *addr, unsigned long count)
 292{
 293        /* Don't allow overflow */
 294        if ((unsigned long) addr + count < count)
 295                count = -(unsigned long) addr;
 296
 297        memcpy(addr, buf, count);
 298        return(count);
 299}
 300
 301/*
 302 *      vmalloc  -  allocate virtually continguos memory
 303 *
 304 *      @size:          allocation size
 305 *
 306 *      Allocate enough pages to cover @size from the page level
 307 *      allocator and map them into continguos kernel virtual space.
 308 *
 309 *      For tight control over page level allocator and protection flags
 310 *      use __vmalloc() instead.
 311 */
 312void *vmalloc(unsigned long size)
 313{
 314       return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 315}
 316EXPORT_SYMBOL(vmalloc);
 317
 318/*
 319 *      vzalloc - allocate virtually continguos memory with zero fill
 320 *
 321 *      @size:          allocation size
 322 *
 323 *      Allocate enough pages to cover @size from the page level
 324 *      allocator and map them into continguos kernel virtual space.
 325 *      The memory allocated is set to zero.
 326 *
 327 *      For tight control over page level allocator and protection flags
 328 *      use __vmalloc() instead.
 329 */
 330void *vzalloc(unsigned long size)
 331{
 332        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 333                        PAGE_KERNEL);
 334}
 335EXPORT_SYMBOL(vzalloc);
 336
 337/**
 338 * vmalloc_node - allocate memory on a specific node
 339 * @size:       allocation size
 340 * @node:       numa node
 341 *
 342 * Allocate enough pages to cover @size from the page level
 343 * allocator and map them into contiguous kernel virtual space.
 344 *
 345 * For tight control over page level allocator and protection flags
 346 * use __vmalloc() instead.
 347 */
 348void *vmalloc_node(unsigned long size, int node)
 349{
 350        return vmalloc(size);
 351}
 352EXPORT_SYMBOL(vmalloc_node);
 353
 354/**
 355 * vzalloc_node - allocate memory on a specific node with zero fill
 356 * @size:       allocation size
 357 * @node:       numa node
 358 *
 359 * Allocate enough pages to cover @size from the page level
 360 * allocator and map them into contiguous kernel virtual space.
 361 * The memory allocated is set to zero.
 362 *
 363 * For tight control over page level allocator and protection flags
 364 * use __vmalloc() instead.
 365 */
 366void *vzalloc_node(unsigned long size, int node)
 367{
 368        return vzalloc(size);
 369}
 370EXPORT_SYMBOL(vzalloc_node);
 371
 372#ifndef PAGE_KERNEL_EXEC
 373# define PAGE_KERNEL_EXEC PAGE_KERNEL
 374#endif
 375
 376/**
 377 *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 378 *      @size:          allocation size
 379 *
 380 *      Kernel-internal function to allocate enough pages to cover @size
 381 *      the page level allocator and map them into contiguous and
 382 *      executable kernel virtual space.
 383 *
 384 *      For tight control over page level allocator and protection flags
 385 *      use __vmalloc() instead.
 386 */
 387
 388void *vmalloc_exec(unsigned long size)
 389{
 390        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 391}
 392
 393/**
 394 * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 395 *      @size:          allocation size
 396 *
 397 *      Allocate enough 32bit PA addressable pages to cover @size from the
 398 *      page level allocator and map them into continguos kernel virtual space.
 399 */
 400void *vmalloc_32(unsigned long size)
 401{
 402        return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 403}
 404EXPORT_SYMBOL(vmalloc_32);
 405
 406/**
 407 * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 408 *      @size:          allocation size
 409 *
 410 * The resulting memory area is 32bit addressable and zeroed so it can be
 411 * mapped to userspace without leaking data.
 412 *
 413 * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 414 * remap_vmalloc_range() are permissible.
 415 */
 416void *vmalloc_32_user(unsigned long size)
 417{
 418        /*
 419         * We'll have to sort out the ZONE_DMA bits for 64-bit,
 420         * but for now this can simply use vmalloc_user() directly.
 421         */
 422        return vmalloc_user(size);
 423}
 424EXPORT_SYMBOL(vmalloc_32_user);
 425
 426void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 427{
 428        BUG();
 429        return NULL;
 430}
 431EXPORT_SYMBOL(vmap);
 432
 433void vunmap(const void *addr)
 434{
 435        BUG();
 436}
 437EXPORT_SYMBOL(vunmap);
 438
 439void *vm_map_ram(struct page **pages, unsigned int count, int node, pgprot_t prot)
 440{
 441        BUG();
 442        return NULL;
 443}
 444EXPORT_SYMBOL(vm_map_ram);
 445
 446void vm_unmap_ram(const void *mem, unsigned int count)
 447{
 448        BUG();
 449}
 450EXPORT_SYMBOL(vm_unmap_ram);
 451
 452void vm_unmap_aliases(void)
 453{
 454}
 455EXPORT_SYMBOL_GPL(vm_unmap_aliases);
 456
 457/*
 458 * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 459 * have one.
 460 */
 461void  __attribute__((weak)) vmalloc_sync_all(void)
 462{
 463}
 464
 465/**
 466 *      alloc_vm_area - allocate a range of kernel address space
 467 *      @size:          size of the area
 468 *
 469 *      Returns:        NULL on failure, vm_struct on success
 470 *
 471 *      This function reserves a range of kernel address space, and
 472 *      allocates pagetables to map that range.  No actual mappings
 473 *      are created.  If the kernel address space is not shared
 474 *      between processes, it syncs the pagetable across all
 475 *      processes.
 476 */
 477struct vm_struct *alloc_vm_area(size_t size, pte_t **ptes)
 478{
 479        BUG();
 480        return NULL;
 481}
 482EXPORT_SYMBOL_GPL(alloc_vm_area);
 483
 484void free_vm_area(struct vm_struct *area)
 485{
 486        BUG();
 487}
 488EXPORT_SYMBOL_GPL(free_vm_area);
 489
 490int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 491                   struct page *page)
 492{
 493        return -EINVAL;
 494}
 495EXPORT_SYMBOL(vm_insert_page);
 496
 497/*
 498 *  sys_brk() for the most part doesn't need the global kernel
 499 *  lock, except when an application is doing something nasty
 500 *  like trying to un-brk an area that has already been mapped
 501 *  to a regular file.  in this case, the unmapping will need
 502 *  to invoke file system routines that need the global lock.
 503 */
 504SYSCALL_DEFINE1(brk, unsigned long, brk)
 505{
 506        struct mm_struct *mm = current->mm;
 507
 508        if (brk < mm->start_brk || brk > mm->context.end_brk)
 509                return mm->brk;
 510
 511        if (mm->brk == brk)
 512                return mm->brk;
 513
 514        /*
 515         * Always allow shrinking brk
 516         */
 517        if (brk <= mm->brk) {
 518                mm->brk = brk;
 519                return brk;
 520        }
 521
 522        /*
 523         * Ok, looks good - let it rip.
 524         */
 525        flush_icache_range(mm->brk, brk);
 526        return mm->brk = brk;
 527}
 528
 529/*
 530 * initialise the VMA and region record slabs
 531 */
 532void __init mmap_init(void)
 533{
 534        int ret;
 535
 536        ret = percpu_counter_init(&vm_committed_as, 0);
 537        VM_BUG_ON(ret);
 538        vm_region_jar = KMEM_CACHE(vm_region, SLAB_PANIC);
 539}
 540
 541/*
 542 * validate the region tree
 543 * - the caller must hold the region lock
 544 */
 545#ifdef CONFIG_DEBUG_NOMMU_REGIONS
 546static noinline void validate_nommu_regions(void)
 547{
 548        struct vm_region *region, *last;
 549        struct rb_node *p, *lastp;
 550
 551        lastp = rb_first(&nommu_region_tree);
 552        if (!lastp)
 553                return;
 554
 555        last = rb_entry(lastp, struct vm_region, vm_rb);
 556        BUG_ON(unlikely(last->vm_end <= last->vm_start));
 557        BUG_ON(unlikely(last->vm_top < last->vm_end));
 558
 559        while ((p = rb_next(lastp))) {
 560                region = rb_entry(p, struct vm_region, vm_rb);
 561                last = rb_entry(lastp, struct vm_region, vm_rb);
 562
 563                BUG_ON(unlikely(region->vm_end <= region->vm_start));
 564                BUG_ON(unlikely(region->vm_top < region->vm_end));
 565                BUG_ON(unlikely(region->vm_start < last->vm_top));
 566
 567                lastp = p;
 568        }
 569}
 570#else
 571static void validate_nommu_regions(void)
 572{
 573}
 574#endif
 575
 576/*
 577 * add a region into the global tree
 578 */
 579static void add_nommu_region(struct vm_region *region)
 580{
 581        struct vm_region *pregion;
 582        struct rb_node **p, *parent;
 583
 584        validate_nommu_regions();
 585
 586        parent = NULL;
 587        p = &nommu_region_tree.rb_node;
 588        while (*p) {
 589                parent = *p;
 590                pregion = rb_entry(parent, struct vm_region, vm_rb);
 591                if (region->vm_start < pregion->vm_start)
 592                        p = &(*p)->rb_left;
 593                else if (region->vm_start > pregion->vm_start)
 594                        p = &(*p)->rb_right;
 595                else if (pregion == region)
 596                        return;
 597                else
 598                        BUG();
 599        }
 600
 601        rb_link_node(&region->vm_rb, parent, p);
 602        rb_insert_color(&region->vm_rb, &nommu_region_tree);
 603
 604        validate_nommu_regions();
 605}
 606
 607/*
 608 * delete a region from the global tree
 609 */
 610static void delete_nommu_region(struct vm_region *region)
 611{
 612        BUG_ON(!nommu_region_tree.rb_node);
 613
 614        validate_nommu_regions();
 615        rb_erase(&region->vm_rb, &nommu_region_tree);
 616        validate_nommu_regions();
 617}
 618
 619/*
 620 * free a contiguous series of pages
 621 */
 622static void free_page_series(unsigned long from, unsigned long to)
 623{
 624        for (; from < to; from += PAGE_SIZE) {
 625                struct page *page = virt_to_page(from);
 626
 627                kdebug("- free %lx", from);
 628                atomic_long_dec(&mmap_pages_allocated);
 629                if (page_count(page) != 1)
 630                        kdebug("free page %p: refcount not one: %d",
 631                               page, page_count(page));
 632                put_page(page);
 633        }
 634}
 635
 636/*
 637 * release a reference to a region
 638 * - the caller must hold the region semaphore for writing, which this releases
 639 * - the region may not have been added to the tree yet, in which case vm_top
 640 *   will equal vm_start
 641 */
 642static void __put_nommu_region(struct vm_region *region)
 643        __releases(nommu_region_sem)
 644{
 645        kenter("%p{%d}", region, region->vm_usage);
 646
 647        BUG_ON(!nommu_region_tree.rb_node);
 648
 649        if (--region->vm_usage == 0) {
 650                if (region->vm_top > region->vm_start)
 651                        delete_nommu_region(region);
 652                up_write(&nommu_region_sem);
 653
 654                if (region->vm_file)
 655                        fput(region->vm_file);
 656
 657                /* IO memory and memory shared directly out of the pagecache
 658                 * from ramfs/tmpfs mustn't be released here */
 659                if (region->vm_flags & VM_MAPPED_COPY) {
 660                        kdebug("free series");
 661                        free_page_series(region->vm_start, region->vm_top);
 662                }
 663                kmem_cache_free(vm_region_jar, region);
 664        } else {
 665                up_write(&nommu_region_sem);
 666        }
 667}
 668
 669/*
 670 * release a reference to a region
 671 */
 672static void put_nommu_region(struct vm_region *region)
 673{
 674        down_write(&nommu_region_sem);
 675        __put_nommu_region(region);
 676}
 677
 678/*
 679 * update protection on a vma
 680 */
 681static void protect_vma(struct vm_area_struct *vma, unsigned long flags)
 682{
 683#ifdef CONFIG_MPU
 684        struct mm_struct *mm = vma->vm_mm;
 685        long start = vma->vm_start & PAGE_MASK;
 686        while (start < vma->vm_end) {
 687                protect_page(mm, start, flags);
 688                start += PAGE_SIZE;
 689        }
 690        update_protections(mm);
 691#endif
 692}
 693
 694/*
 695 * add a VMA into a process's mm_struct in the appropriate place in the list
 696 * and tree and add to the address space's page tree also if not an anonymous
 697 * page
 698 * - should be called with mm->mmap_sem held writelocked
 699 */
 700static void add_vma_to_mm(struct mm_struct *mm, struct vm_area_struct *vma)
 701{
 702        struct vm_area_struct *pvma, *prev;
 703        struct address_space *mapping;
 704        struct rb_node **p, *parent, *rb_prev;
 705
 706        kenter(",%p", vma);
 707
 708        BUG_ON(!vma->vm_region);
 709
 710        mm->map_count++;
 711        vma->vm_mm = mm;
 712
 713        protect_vma(vma, vma->vm_flags);
 714
 715        /* add the VMA to the mapping */
 716        if (vma->vm_file) {
 717                mapping = vma->vm_file->f_mapping;
 718
 719                mutex_lock(&mapping->i_mmap_mutex);
 720                flush_dcache_mmap_lock(mapping);
 721                vma_interval_tree_insert(vma, &mapping->i_mmap);
 722                flush_dcache_mmap_unlock(mapping);
 723                mutex_unlock(&mapping->i_mmap_mutex);
 724        }
 725
 726        /* add the VMA to the tree */
 727        parent = rb_prev = NULL;
 728        p = &mm->mm_rb.rb_node;
 729        while (*p) {
 730                parent = *p;
 731                pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 732
 733                /* sort by: start addr, end addr, VMA struct addr in that order
 734                 * (the latter is necessary as we may get identical VMAs) */
 735                if (vma->vm_start < pvma->vm_start)
 736                        p = &(*p)->rb_left;
 737                else if (vma->vm_start > pvma->vm_start) {
 738                        rb_prev = parent;
 739                        p = &(*p)->rb_right;
 740                } else if (vma->vm_end < pvma->vm_end)
 741                        p = &(*p)->rb_left;
 742                else if (vma->vm_end > pvma->vm_end) {
 743                        rb_prev = parent;
 744                        p = &(*p)->rb_right;
 745                } else if (vma < pvma)
 746                        p = &(*p)->rb_left;
 747                else if (vma > pvma) {
 748                        rb_prev = parent;
 749                        p = &(*p)->rb_right;
 750                } else
 751                        BUG();
 752        }
 753
 754        rb_link_node(&vma->vm_rb, parent, p);
 755        rb_insert_color(&vma->vm_rb, &mm->mm_rb);
 756
 757        /* add VMA to the VMA list also */
 758        prev = NULL;
 759        if (rb_prev)
 760                prev = rb_entry(rb_prev, struct vm_area_struct, vm_rb);
 761
 762        __vma_link_list(mm, vma, prev, parent);
 763}
 764
 765/*
 766 * delete a VMA from its owning mm_struct and address space
 767 */
 768static void delete_vma_from_mm(struct vm_area_struct *vma)
 769{
 770        struct address_space *mapping;
 771        struct mm_struct *mm = vma->vm_mm;
 772
 773        kenter("%p", vma);
 774
 775        protect_vma(vma, 0);
 776
 777        mm->map_count--;
 778        if (mm->mmap_cache == vma)
 779                mm->mmap_cache = NULL;
 780
 781        /* remove the VMA from the mapping */
 782        if (vma->vm_file) {
 783                mapping = vma->vm_file->f_mapping;
 784
 785                mutex_lock(&mapping->i_mmap_mutex);
 786                flush_dcache_mmap_lock(mapping);
 787                vma_interval_tree_remove(vma, &mapping->i_mmap);
 788                flush_dcache_mmap_unlock(mapping);
 789                mutex_unlock(&mapping->i_mmap_mutex);
 790        }
 791
 792        /* remove from the MM's tree and list */
 793        rb_erase(&vma->vm_rb, &mm->mm_rb);
 794
 795        if (vma->vm_prev)
 796                vma->vm_prev->vm_next = vma->vm_next;
 797        else
 798                mm->mmap = vma->vm_next;
 799
 800        if (vma->vm_next)
 801                vma->vm_next->vm_prev = vma->vm_prev;
 802}
 803
 804/*
 805 * destroy a VMA record
 806 */
 807static void delete_vma(struct mm_struct *mm, struct vm_area_struct *vma)
 808{
 809        kenter("%p", vma);
 810        if (vma->vm_ops && vma->vm_ops->close)
 811                vma->vm_ops->close(vma);
 812        if (vma->vm_file)
 813                fput(vma->vm_file);
 814        put_nommu_region(vma->vm_region);
 815        kmem_cache_free(vm_area_cachep, vma);
 816}
 817
 818/*
 819 * look up the first VMA in which addr resides, NULL if none
 820 * - should be called with mm->mmap_sem at least held readlocked
 821 */
 822struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 823{
 824        struct vm_area_struct *vma;
 825
 826        /* check the cache first */
 827        vma = ACCESS_ONCE(mm->mmap_cache);
 828        if (vma && vma->vm_start <= addr && vma->vm_end > addr)
 829                return vma;
 830
 831        /* trawl the list (there may be multiple mappings in which addr
 832         * resides) */
 833        for (vma = mm->mmap; vma; vma = vma->vm_next) {
 834                if (vma->vm_start > addr)
 835                        return NULL;
 836                if (vma->vm_end > addr) {
 837                        mm->mmap_cache = vma;
 838                        return vma;
 839                }
 840        }
 841
 842        return NULL;
 843}
 844EXPORT_SYMBOL(find_vma);
 845
 846/*
 847 * find a VMA
 848 * - we don't extend stack VMAs under NOMMU conditions
 849 */
 850struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 851{
 852        return find_vma(mm, addr);
 853}
 854
 855/*
 856 * expand a stack to a given address
 857 * - not supported under NOMMU conditions
 858 */
 859int expand_stack(struct vm_area_struct *vma, unsigned long address)
 860{
 861        return -ENOMEM;
 862}
 863
 864/*
 865 * look up the first VMA exactly that exactly matches addr
 866 * - should be called with mm->mmap_sem at least held readlocked
 867 */
 868static struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 869                                             unsigned long addr,
 870                                             unsigned long len)
 871{
 872        struct vm_area_struct *vma;
 873        unsigned long end = addr + len;
 874
 875        /* check the cache first */
 876        vma = mm->mmap_cache;
 877        if (vma && vma->vm_start == addr && vma->vm_end == end)
 878                return vma;
 879
 880        /* trawl the list (there may be multiple mappings in which addr
 881         * resides) */
 882        for (vma = mm->mmap; vma; vma = vma->vm_next) {
 883                if (vma->vm_start < addr)
 884                        continue;
 885                if (vma->vm_start > addr)
 886                        return NULL;
 887                if (vma->vm_end == end) {
 888                        mm->mmap_cache = vma;
 889                        return vma;
 890                }
 891        }
 892
 893        return NULL;
 894}
 895
 896/*
 897 * determine whether a mapping should be permitted and, if so, what sort of
 898 * mapping we're capable of supporting
 899 */
 900static int validate_mmap_request(struct file *file,
 901                                 unsigned long addr,
 902                                 unsigned long len,
 903                                 unsigned long prot,
 904                                 unsigned long flags,
 905                                 unsigned long pgoff,
 906                                 unsigned long *_capabilities)
 907{
 908        unsigned long capabilities, rlen;
 909        int ret;
 910
 911        /* do the simple checks first */
 912        if (flags & MAP_FIXED) {
 913                printk(KERN_DEBUG
 914                       "%d: Can't do fixed-address/overlay mmap of RAM\n",
 915                       current->pid);
 916                return -EINVAL;
 917        }
 918
 919        if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 920            (flags & MAP_TYPE) != MAP_SHARED)
 921                return -EINVAL;
 922
 923        if (!len)
 924                return -EINVAL;
 925
 926        /* Careful about overflows.. */
 927        rlen = PAGE_ALIGN(len);
 928        if (!rlen || rlen > TASK_SIZE)
 929                return -ENOMEM;
 930
 931        /* offset overflow? */
 932        if ((pgoff + (rlen >> PAGE_SHIFT)) < pgoff)
 933                return -EOVERFLOW;
 934
 935        if (file) {
 936                /* validate file mapping requests */
 937                struct address_space *mapping;
 938
 939                /* files must support mmap */
 940                if (!file->f_op || !file->f_op->mmap)
 941                        return -ENODEV;
 942
 943                /* work out if what we've got could possibly be shared
 944                 * - we support chardevs that provide their own "memory"
 945                 * - we support files/blockdevs that are memory backed
 946                 */
 947                mapping = file->f_mapping;
 948                if (!mapping)
 949                        mapping = file_inode(file)->i_mapping;
 950
 951                capabilities = 0;
 952                if (mapping && mapping->backing_dev_info)
 953                        capabilities = mapping->backing_dev_info->capabilities;
 954
 955                if (!capabilities) {
 956                        /* no explicit capabilities set, so assume some
 957                         * defaults */
 958                        switch (file_inode(file)->i_mode & S_IFMT) {
 959                        case S_IFREG:
 960                        case S_IFBLK:
 961                                capabilities = BDI_CAP_MAP_COPY;
 962                                break;
 963
 964                        case S_IFCHR:
 965                                capabilities =
 966                                        BDI_CAP_MAP_DIRECT |
 967                                        BDI_CAP_READ_MAP |
 968                                        BDI_CAP_WRITE_MAP;
 969                                break;
 970
 971                        default:
 972                                return -EINVAL;
 973                        }
 974                }
 975
 976                /* eliminate any capabilities that we can't support on this
 977                 * device */
 978                if (!file->f_op->get_unmapped_area)
 979                        capabilities &= ~BDI_CAP_MAP_DIRECT;
 980                if (!file->f_op->read)
 981                        capabilities &= ~BDI_CAP_MAP_COPY;
 982
 983                /* The file shall have been opened with read permission. */
 984                if (!(file->f_mode & FMODE_READ))
 985                        return -EACCES;
 986
 987                if (flags & MAP_SHARED) {
 988                        /* do checks for writing, appending and locking */
 989                        if ((prot & PROT_WRITE) &&
 990                            !(file->f_mode & FMODE_WRITE))
 991                                return -EACCES;
 992
 993                        if (IS_APPEND(file_inode(file)) &&
 994                            (file->f_mode & FMODE_WRITE))
 995                                return -EACCES;
 996
 997                        if (locks_verify_locked(file_inode(file)))
 998                                return -EAGAIN;
 999
1000                        if (!(capabilities & BDI_CAP_MAP_DIRECT))
1001                                return -ENODEV;
1002
1003                        /* we mustn't privatise shared mappings */
1004                        capabilities &= ~BDI_CAP_MAP_COPY;
1005                }
1006                else {
1007                        /* we're going to read the file into private memory we
1008                         * allocate */
1009                        if (!(capabilities & BDI_CAP_MAP_COPY))
1010                                return -ENODEV;
1011
1012                        /* we don't permit a private writable mapping to be
1013                         * shared with the backing device */
1014                        if (prot & PROT_WRITE)
1015                                capabilities &= ~BDI_CAP_MAP_DIRECT;
1016                }
1017
1018                if (capabilities & BDI_CAP_MAP_DIRECT) {
1019                        if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
1020                            ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
1021                            ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
1022                            ) {
1023                                capabilities &= ~BDI_CAP_MAP_DIRECT;
1024                                if (flags & MAP_SHARED) {
1025                                        printk(KERN_WARNING
1026                                               "MAP_SHARED not completely supported on !MMU\n");
1027                                        return -EINVAL;
1028                                }
1029                        }
1030                }
1031
1032                /* handle executable mappings and implied executable
1033                 * mappings */
1034                if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
1035                        if (prot & PROT_EXEC)
1036                                return -EPERM;
1037                }
1038                else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
1039                        /* handle implication of PROT_EXEC by PROT_READ */
1040                        if (current->personality & READ_IMPLIES_EXEC) {
1041                                if (capabilities & BDI_CAP_EXEC_MAP)
1042                                        prot |= PROT_EXEC;
1043                        }
1044                }
1045                else if ((prot & PROT_READ) &&
1046                         (prot & PROT_EXEC) &&
1047                         !(capabilities & BDI_CAP_EXEC_MAP)
1048                         ) {
1049                        /* backing file is not executable, try to copy */
1050                        capabilities &= ~BDI_CAP_MAP_DIRECT;
1051                }
1052        }
1053        else {
1054                /* anonymous mappings are always memory backed and can be
1055                 * privately mapped
1056                 */
1057                capabilities = BDI_CAP_MAP_COPY;
1058
1059                /* handle PROT_EXEC implication by PROT_READ */
1060                if ((prot & PROT_READ) &&
1061                    (current->personality & READ_IMPLIES_EXEC))
1062                        prot |= PROT_EXEC;
1063        }
1064
1065        /* allow the security API to have its say */
1066        ret = security_mmap_addr(addr);
1067        if (ret < 0)
1068                return ret;
1069
1070        /* looks okay */
1071        *_capabilities = capabilities;
1072        return 0;
1073}
1074
1075/*
1076 * we've determined that we can make the mapping, now translate what we
1077 * now know into VMA flags
1078 */
1079static unsigned long determine_vm_flags(struct file *file,
1080                                        unsigned long prot,
1081                                        unsigned long flags,
1082                                        unsigned long capabilities)
1083{
1084        unsigned long vm_flags;
1085
1086        vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
1087        /* vm_flags |= mm->def_flags; */
1088
1089        if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
1090                /* attempt to share read-only copies of mapped file chunks */
1091                vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1092                if (file && !(prot & PROT_WRITE))
1093                        vm_flags |= VM_MAYSHARE;
1094        } else {
1095                /* overlay a shareable mapping on the backing device or inode
1096                 * if possible - used for chardevs, ramfs/tmpfs/shmfs and
1097                 * romfs/cramfs */
1098                vm_flags |= VM_MAYSHARE | (capabilities & BDI_CAP_VMFLAGS);
1099                if (flags & MAP_SHARED)
1100                        vm_flags |= VM_SHARED;
1101        }
1102
1103        /* refuse to let anyone share private mappings with this process if
1104         * it's being traced - otherwise breakpoints set in it may interfere
1105         * with another untraced process
1106         */
1107        if ((flags & MAP_PRIVATE) && current->ptrace)
1108                vm_flags &= ~VM_MAYSHARE;
1109
1110        return vm_flags;
1111}
1112
1113/*
1114 * set up a shared mapping on a file (the driver or filesystem provides and
1115 * pins the storage)
1116 */
1117static int do_mmap_shared_file(struct vm_area_struct *vma)
1118{
1119        int ret;
1120
1121        ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1122        if (ret == 0) {
1123                vma->vm_region->vm_top = vma->vm_region->vm_end;
1124                return 0;
1125        }
1126        if (ret != -ENOSYS)
1127                return ret;
1128
1129        /* getting -ENOSYS indicates that direct mmap isn't possible (as
1130         * opposed to tried but failed) so we can only give a suitable error as
1131         * it's not possible to make a private copy if MAP_SHARED was given */
1132        return -ENODEV;
1133}
1134
1135/*
1136 * set up a private mapping or an anonymous shared mapping
1137 */
1138static int do_mmap_private(struct vm_area_struct *vma,
1139                           struct vm_region *region,
1140                           unsigned long len,
1141                           unsigned long capabilities)
1142{
1143        struct page *pages;
1144        unsigned long total, point, n;
1145        void *base;
1146        int ret, order;
1147
1148        /* invoke the file's mapping function so that it can keep track of
1149         * shared mappings on devices or memory
1150         * - VM_MAYSHARE will be set if it may attempt to share
1151         */
1152        if (capabilities & BDI_CAP_MAP_DIRECT) {
1153                ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
1154                if (ret == 0) {
1155                        /* shouldn't return success if we're not sharing */
1156                        BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
1157                        vma->vm_region->vm_top = vma->vm_region->vm_end;
1158                        return 0;
1159                }
1160                if (ret != -ENOSYS)
1161                        return ret;
1162
1163                /* getting an ENOSYS error indicates that direct mmap isn't
1164                 * possible (as opposed to tried but failed) so we'll try to
1165                 * make a private copy of the data and map that instead */
1166        }
1167
1168
1169        /* allocate some memory to hold the mapping
1170         * - note that this may not return a page-aligned address if the object
1171         *   we're allocating is smaller than a page
1172         */
1173        order = get_order(len);
1174        kdebug("alloc order %d for %lx", order, len);
1175
1176        pages = alloc_pages(GFP_KERNEL, order);
1177        if (!pages)
1178                goto enomem;
1179
1180        total = 1 << order;
1181        atomic_long_add(total, &mmap_pages_allocated);
1182
1183        point = len >> PAGE_SHIFT;
1184
1185        /* we allocated a power-of-2 sized page set, so we may want to trim off
1186         * the excess */
1187        if (sysctl_nr_trim_pages && total - point >= sysctl_nr_trim_pages) {
1188                while (total > point) {
1189                        order = ilog2(total - point);
1190                        n = 1 << order;
1191                        kdebug("shave %lu/%lu @%lu", n, total - point, total);
1192                        atomic_long_sub(n, &mmap_pages_allocated);
1193                        total -= n;
1194                        set_page_refcounted(pages + total);
1195                        __free_pages(pages + total, order);
1196                }
1197        }
1198
1199        for (point = 1; point < total; point++)
1200                set_page_refcounted(&pages[point]);
1201
1202        base = page_address(pages);
1203        region->vm_flags = vma->vm_flags |= VM_MAPPED_COPY;
1204        region->vm_start = (unsigned long) base;
1205        region->vm_end   = region->vm_start + len;
1206        region->vm_top   = region->vm_start + (total << PAGE_SHIFT);
1207
1208        vma->vm_start = region->vm_start;
1209        vma->vm_end   = region->vm_start + len;
1210
1211        if (vma->vm_file) {
1212                /* read the contents of a file into the copy */
1213                mm_segment_t old_fs;
1214                loff_t fpos;
1215
1216                fpos = vma->vm_pgoff;
1217                fpos <<= PAGE_SHIFT;
1218
1219                old_fs = get_fs();
1220                set_fs(KERNEL_DS);
1221                ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
1222                set_fs(old_fs);
1223
1224                if (ret < 0)
1225                        goto error_free;
1226
1227                /* clear the last little bit */
1228                if (ret < len)
1229                        memset(base + ret, 0, len - ret);
1230
1231        }
1232
1233        return 0;
1234
1235error_free:
1236        free_page_series(region->vm_start, region->vm_top);
1237        region->vm_start = vma->vm_start = 0;
1238        region->vm_end   = vma->vm_end = 0;
1239        region->vm_top   = 0;
1240        return ret;
1241
1242enomem:
1243        printk("Allocation of length %lu from process %d (%s) failed\n",
1244               len, current->pid, current->comm);
1245        show_free_areas(0);
1246        return -ENOMEM;
1247}
1248
1249/*
1250 * handle mapping creation for uClinux
1251 */
1252unsigned long do_mmap_pgoff(struct file *file,
1253                            unsigned long addr,
1254                            unsigned long len,
1255                            unsigned long prot,
1256                            unsigned long flags,
1257                            unsigned long pgoff,
1258                            unsigned long *populate)
1259{
1260        struct vm_area_struct *vma;
1261        struct vm_region *region;
1262        struct rb_node *rb;
1263        unsigned long capabilities, vm_flags, result;
1264        int ret;
1265
1266        kenter(",%lx,%lx,%lx,%lx,%lx", addr, len, prot, flags, pgoff);
1267
1268        *populate = 0;
1269
1270        /* decide whether we should attempt the mapping, and if so what sort of
1271         * mapping */
1272        ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
1273                                    &capabilities);
1274        if (ret < 0) {
1275                kleave(" = %d [val]", ret);
1276                return ret;
1277        }
1278
1279        /* we ignore the address hint */
1280        addr = 0;
1281        len = PAGE_ALIGN(len);
1282
1283        /* we've determined that we can make the mapping, now translate what we
1284         * now know into VMA flags */
1285        vm_flags = determine_vm_flags(file, prot, flags, capabilities);
1286
1287        /* we're going to need to record the mapping */
1288        region = kmem_cache_zalloc(vm_region_jar, GFP_KERNEL);
1289        if (!region)
1290                goto error_getting_region;
1291
1292        vma = kmem_cache_zalloc(vm_area_cachep, GFP_KERNEL);
1293        if (!vma)
1294                goto error_getting_vma;
1295
1296        region->vm_usage = 1;
1297        region->vm_flags = vm_flags;
1298        region->vm_pgoff = pgoff;
1299
1300        INIT_LIST_HEAD(&vma->anon_vma_chain);
1301        vma->vm_flags = vm_flags;
1302        vma->vm_pgoff = pgoff;
1303
1304        if (file) {
1305                region->vm_file = get_file(file);
1306                vma->vm_file = get_file(file);
1307        }
1308
1309        down_write(&nommu_region_sem);
1310
1311        /* if we want to share, we need to check for regions created by other
1312         * mmap() calls that overlap with our proposed mapping
1313         * - we can only share with a superset match on most regular files
1314         * - shared mappings on character devices and memory backed files are
1315         *   permitted to overlap inexactly as far as we are concerned for in
1316         *   these cases, sharing is handled in the driver or filesystem rather
1317         *   than here
1318         */
1319        if (vm_flags & VM_MAYSHARE) {
1320                struct vm_region *pregion;
1321                unsigned long pglen, rpglen, pgend, rpgend, start;
1322
1323                pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
1324                pgend = pgoff + pglen;
1325
1326                for (rb = rb_first(&nommu_region_tree); rb; rb = rb_next(rb)) {
1327                        pregion = rb_entry(rb, struct vm_region, vm_rb);
1328
1329                        if (!(pregion->vm_flags & VM_MAYSHARE))
1330                                continue;
1331
1332                        /* search for overlapping mappings on the same file */
1333                        if (file_inode(pregion->vm_file) !=
1334                            file_inode(file))
1335                                continue;
1336
1337                        if (pregion->vm_pgoff >= pgend)
1338                                continue;
1339
1340                        rpglen = pregion->vm_end - pregion->vm_start;
1341                        rpglen = (rpglen + PAGE_SIZE - 1) >> PAGE_SHIFT;
1342                        rpgend = pregion->vm_pgoff + rpglen;
1343                        if (pgoff >= rpgend)
1344                                continue;
1345
1346                        /* handle inexactly overlapping matches between
1347                         * mappings */
1348                        if ((pregion->vm_pgoff != pgoff || rpglen != pglen) &&
1349                            !(pgoff >= pregion->vm_pgoff && pgend <= rpgend)) {
1350                                /* new mapping is not a subset of the region */
1351                                if (!(capabilities & BDI_CAP_MAP_DIRECT))
1352                                        goto sharing_violation;
1353                                continue;
1354                        }
1355
1356                        /* we've found a region we can share */
1357                        pregion->vm_usage++;
1358                        vma->vm_region = pregion;
1359                        start = pregion->vm_start;
1360                        start += (pgoff - pregion->vm_pgoff) << PAGE_SHIFT;
1361                        vma->vm_start = start;
1362                        vma->vm_end = start + len;
1363
1364                        if (pregion->vm_flags & VM_MAPPED_COPY) {
1365                                kdebug("share copy");
1366                                vma->vm_flags |= VM_MAPPED_COPY;
1367                        } else {
1368                                kdebug("share mmap");
1369                                ret = do_mmap_shared_file(vma);
1370                                if (ret < 0) {
1371                                        vma->vm_region = NULL;
1372                                        vma->vm_start = 0;
1373                                        vma->vm_end = 0;
1374                                        pregion->vm_usage--;
1375                                        pregion = NULL;
1376                                        goto error_just_free;
1377                                }
1378                        }
1379                        fput(region->vm_file);
1380                        kmem_cache_free(vm_region_jar, region);
1381                        region = pregion;
1382                        result = start;
1383                        goto share;
1384                }
1385
1386                /* obtain the address at which to make a shared mapping
1387                 * - this is the hook for quasi-memory character devices to
1388                 *   tell us the location of a shared mapping
1389                 */
1390                if (capabilities & BDI_CAP_MAP_DIRECT) {
1391                        addr = file->f_op->get_unmapped_area(file, addr, len,
1392                                                             pgoff, flags);
1393                        if (IS_ERR_VALUE(addr)) {
1394                                ret = addr;
1395                                if (ret != -ENOSYS)
1396                                        goto error_just_free;
1397
1398                                /* the driver refused to tell us where to site
1399                                 * the mapping so we'll have to attempt to copy
1400                                 * it */
1401                                ret = -ENODEV;
1402                                if (!(capabilities & BDI_CAP_MAP_COPY))
1403                                        goto error_just_free;
1404
1405                                capabilities &= ~BDI_CAP_MAP_DIRECT;
1406                        } else {
1407                                vma->vm_start = region->vm_start = addr;
1408                                vma->vm_end = region->vm_end = addr + len;
1409                        }
1410                }
1411        }
1412
1413        vma->vm_region = region;
1414
1415        /* set up the mapping
1416         * - the region is filled in if BDI_CAP_MAP_DIRECT is still set
1417         */
1418        if (file && vma->vm_flags & VM_SHARED)
1419                ret = do_mmap_shared_file(vma);
1420        else
1421                ret = do_mmap_private(vma, region, len, capabilities);
1422        if (ret < 0)
1423                goto error_just_free;
1424        add_nommu_region(region);
1425
1426        /* clear anonymous mappings that don't ask for uninitialized data */
1427        if (!vma->vm_file && !(flags & MAP_UNINITIALIZED))
1428                memset((void *)region->vm_start, 0,
1429                       region->vm_end - region->vm_start);
1430
1431        /* okay... we have a mapping; now we have to register it */
1432        result = vma->vm_start;
1433
1434        current->mm->total_vm += len >> PAGE_SHIFT;
1435
1436share:
1437        add_vma_to_mm(current->mm, vma);
1438
1439        /* we flush the region from the icache only when the first executable
1440         * mapping of it is made  */
1441        if (vma->vm_flags & VM_EXEC && !region->vm_icache_flushed) {
1442                flush_icache_range(region->vm_start, region->vm_end);
1443                region->vm_icache_flushed = true;
1444        }
1445
1446        up_write(&nommu_region_sem);
1447
1448        kleave(" = %lx", result);
1449        return result;
1450
1451error_just_free:
1452        up_write(&nommu_region_sem);
1453error:
1454        if (region->vm_file)
1455                fput(region->vm_file);
1456        kmem_cache_free(vm_region_jar, region);
1457        if (vma->vm_file)
1458                fput(vma->vm_file);
1459        kmem_cache_free(vm_area_cachep, vma);
1460        kleave(" = %d", ret);
1461        return ret;
1462
1463sharing_violation:
1464        up_write(&nommu_region_sem);
1465        printk(KERN_WARNING "Attempt to share mismatched mappings\n");
1466        ret = -EINVAL;
1467        goto error;
1468
1469error_getting_vma:
1470        kmem_cache_free(vm_region_jar, region);
1471        printk(KERN_WARNING "Allocation of vma for %lu byte allocation"
1472               " from process %d failed\n",
1473               len, current->pid);
1474        show_free_areas(0);
1475        return -ENOMEM;
1476
1477error_getting_region:
1478        printk(KERN_WARNING "Allocation of vm region for %lu byte allocation"
1479               " from process %d failed\n",
1480               len, current->pid);
1481        show_free_areas(0);
1482        return -ENOMEM;
1483}
1484
1485SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1486                unsigned long, prot, unsigned long, flags,
1487                unsigned long, fd, unsigned long, pgoff)
1488{
1489        struct file *file = NULL;
1490        unsigned long retval = -EBADF;
1491
1492        audit_mmap_fd(fd, flags);
1493        if (!(flags & MAP_ANONYMOUS)) {
1494                file = fget(fd);
1495                if (!file)
1496                        goto out;
1497        }
1498
1499        flags &= ~(MAP_EXECUTABLE | MAP_DENYWRITE);
1500
1501        retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1502
1503        if (file)
1504                fput(file);
1505out:
1506        return retval;
1507}
1508
1509#ifdef __ARCH_WANT_SYS_OLD_MMAP
1510struct mmap_arg_struct {
1511        unsigned long addr;
1512        unsigned long len;
1513        unsigned long prot;
1514        unsigned long flags;
1515        unsigned long fd;
1516        unsigned long offset;
1517};
1518
1519SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1520{
1521        struct mmap_arg_struct a;
1522
1523        if (copy_from_user(&a, arg, sizeof(a)))
1524                return -EFAULT;
1525        if (a.offset & ~PAGE_MASK)
1526                return -EINVAL;
1527
1528        return sys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1529                              a.offset >> PAGE_SHIFT);
1530}
1531#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1532
1533/*
1534 * split a vma into two pieces at address 'addr', a new vma is allocated either
1535 * for the first part or the tail.
1536 */
1537int split_vma(struct mm_struct *mm, struct vm_area_struct *vma,
1538              unsigned long addr, int new_below)
1539{
1540        struct vm_area_struct *new;
1541        struct vm_region *region;
1542        unsigned long npages;
1543
1544        kenter("");
1545
1546        /* we're only permitted to split anonymous regions (these should have
1547         * only a single usage on the region) */
1548        if (vma->vm_file)
1549                return -ENOMEM;
1550
1551        if (mm->map_count >= sysctl_max_map_count)
1552                return -ENOMEM;
1553
1554        region = kmem_cache_alloc(vm_region_jar, GFP_KERNEL);
1555        if (!region)
1556                return -ENOMEM;
1557
1558        new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
1559        if (!new) {
1560                kmem_cache_free(vm_region_jar, region);
1561                return -ENOMEM;
1562        }
1563
1564        /* most fields are the same, copy all, and then fixup */
1565        *new = *vma;
1566        *region = *vma->vm_region;
1567        new->vm_region = region;
1568
1569        npages = (addr - vma->vm_start) >> PAGE_SHIFT;
1570
1571        if (new_below) {
1572                region->vm_top = region->vm_end = new->vm_end = addr;
1573        } else {
1574                region->vm_start = new->vm_start = addr;
1575                region->vm_pgoff = new->vm_pgoff += npages;
1576        }
1577
1578        if (new->vm_ops && new->vm_ops->open)
1579                new->vm_ops->open(new);
1580
1581        delete_vma_from_mm(vma);
1582        down_write(&nommu_region_sem);
1583        delete_nommu_region(vma->vm_region);
1584        if (new_below) {
1585                vma->vm_region->vm_start = vma->vm_start = addr;
1586                vma->vm_region->vm_pgoff = vma->vm_pgoff += npages;
1587        } else {
1588                vma->vm_region->vm_end = vma->vm_end = addr;
1589                vma->vm_region->vm_top = addr;
1590        }
1591        add_nommu_region(vma->vm_region);
1592        add_nommu_region(new->vm_region);
1593        up_write(&nommu_region_sem);
1594        add_vma_to_mm(mm, vma);
1595        add_vma_to_mm(mm, new);
1596        return 0;
1597}
1598
1599/*
1600 * shrink a VMA by removing the specified chunk from either the beginning or
1601 * the end
1602 */
1603static int shrink_vma(struct mm_struct *mm,
1604                      struct vm_area_struct *vma,
1605                      unsigned long from, unsigned long to)
1606{
1607        struct vm_region *region;
1608
1609        kenter("");
1610
1611        /* adjust the VMA's pointers, which may reposition it in the MM's tree
1612         * and list */
1613        delete_vma_from_mm(vma);
1614        if (from > vma->vm_start)
1615                vma->vm_end = from;
1616        else
1617                vma->vm_start = to;
1618        add_vma_to_mm(mm, vma);
1619
1620        /* cut the backing region down to size */
1621        region = vma->vm_region;
1622        BUG_ON(region->vm_usage != 1);
1623
1624        down_write(&nommu_region_sem);
1625        delete_nommu_region(region);
1626        if (from > region->vm_start) {
1627                to = region->vm_top;
1628                region->vm_top = region->vm_end = from;
1629        } else {
1630                region->vm_start = to;
1631        }
1632        add_nommu_region(region);
1633        up_write(&nommu_region_sem);
1634
1635        free_page_series(from, to);
1636        return 0;
1637}
1638
1639/*
1640 * release a mapping
1641 * - under NOMMU conditions the chunk to be unmapped must be backed by a single
1642 *   VMA, though it need not cover the whole VMA
1643 */
1644int do_munmap(struct mm_struct *mm, unsigned long start, size_t len)
1645{
1646        struct vm_area_struct *vma;
1647        unsigned long end;
1648        int ret;
1649
1650        kenter(",%lx,%zx", start, len);
1651
1652        len = PAGE_ALIGN(len);
1653        if (len == 0)
1654                return -EINVAL;
1655
1656        end = start + len;
1657
1658        /* find the first potentially overlapping VMA */
1659        vma = find_vma(mm, start);
1660        if (!vma) {
1661                static int limit = 0;
1662                if (limit < 5) {
1663                        printk(KERN_WARNING
1664                               "munmap of memory not mmapped by process %d"
1665                               " (%s): 0x%lx-0x%lx\n",
1666                               current->pid, current->comm,
1667                               start, start + len - 1);
1668                        limit++;
1669                }
1670                return -EINVAL;
1671        }
1672
1673        /* we're allowed to split an anonymous VMA but not a file-backed one */
1674        if (vma->vm_file) {
1675                do {
1676                        if (start > vma->vm_start) {
1677                                kleave(" = -EINVAL [miss]");
1678                                return -EINVAL;
1679                        }
1680                        if (end == vma->vm_end)
1681                                goto erase_whole_vma;
1682                        vma = vma->vm_next;
1683                } while (vma);
1684                kleave(" = -EINVAL [split file]");
1685                return -EINVAL;
1686        } else {
1687                /* the chunk must be a subset of the VMA found */
1688                if (start == vma->vm_start && end == vma->vm_end)
1689                        goto erase_whole_vma;
1690                if (start < vma->vm_start || end > vma->vm_end) {
1691                        kleave(" = -EINVAL [superset]");
1692                        return -EINVAL;
1693                }
1694                if (start & ~PAGE_MASK) {
1695                        kleave(" = -EINVAL [unaligned start]");
1696                        return -EINVAL;
1697                }
1698                if (end != vma->vm_end && end & ~PAGE_MASK) {
1699                        kleave(" = -EINVAL [unaligned split]");
1700                        return -EINVAL;
1701                }
1702                if (start != vma->vm_start && end != vma->vm_end) {
1703                        ret = split_vma(mm, vma, start, 1);
1704                        if (ret < 0) {
1705                                kleave(" = %d [split]", ret);
1706                                return ret;
1707                        }
1708                }
1709                return shrink_vma(mm, vma, start, end);
1710        }
1711
1712erase_whole_vma:
1713        delete_vma_from_mm(vma);
1714        delete_vma(mm, vma);
1715        kleave(" = 0");
1716        return 0;
1717}
1718EXPORT_SYMBOL(do_munmap);
1719
1720int vm_munmap(unsigned long addr, size_t len)
1721{
1722        struct mm_struct *mm = current->mm;
1723        int ret;
1724
1725        down_write(&mm->mmap_sem);
1726        ret = do_munmap(mm, addr, len);
1727        up_write(&mm->mmap_sem);
1728        return ret;
1729}
1730EXPORT_SYMBOL(vm_munmap);
1731
1732SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
1733{
1734        return vm_munmap(addr, len);
1735}
1736
1737/*
1738 * release all the mappings made in a process's VM space
1739 */
1740void exit_mmap(struct mm_struct *mm)
1741{
1742        struct vm_area_struct *vma;
1743
1744        if (!mm)
1745                return;
1746
1747        kenter("");
1748
1749        mm->total_vm = 0;
1750
1751        while ((vma = mm->mmap)) {
1752                mm->mmap = vma->vm_next;
1753                delete_vma_from_mm(vma);
1754                delete_vma(mm, vma);
1755                cond_resched();
1756        }
1757
1758        kleave("");
1759}
1760
1761unsigned long vm_brk(unsigned long addr, unsigned long len)
1762{
1763        return -ENOMEM;
1764}
1765
1766/*
1767 * expand (or shrink) an existing mapping, potentially moving it at the same
1768 * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1769 *
1770 * under NOMMU conditions, we only permit changing a mapping's size, and only
1771 * as long as it stays within the region allocated by do_mmap_private() and the
1772 * block is not shareable
1773 *
1774 * MREMAP_FIXED is not supported under NOMMU conditions
1775 */
1776static unsigned long do_mremap(unsigned long addr,
1777                        unsigned long old_len, unsigned long new_len,
1778                        unsigned long flags, unsigned long new_addr)
1779{
1780        struct vm_area_struct *vma;
1781
1782        /* insanity checks first */
1783        old_len = PAGE_ALIGN(old_len);
1784        new_len = PAGE_ALIGN(new_len);
1785        if (old_len == 0 || new_len == 0)
1786                return (unsigned long) -EINVAL;
1787
1788        if (addr & ~PAGE_MASK)
1789                return -EINVAL;
1790
1791        if (flags & MREMAP_FIXED && new_addr != addr)
1792                return (unsigned long) -EINVAL;
1793
1794        vma = find_vma_exact(current->mm, addr, old_len);
1795        if (!vma)
1796                return (unsigned long) -EINVAL;
1797
1798        if (vma->vm_end != vma->vm_start + old_len)
1799                return (unsigned long) -EFAULT;
1800
1801        if (vma->vm_flags & VM_MAYSHARE)
1802                return (unsigned long) -EPERM;
1803
1804        if (new_len > vma->vm_region->vm_end - vma->vm_region->vm_start)
1805                return (unsigned long) -ENOMEM;
1806
1807        /* all checks complete - do it */
1808        vma->vm_end = vma->vm_start + new_len;
1809        return vma->vm_start;
1810}
1811
1812SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
1813                unsigned long, new_len, unsigned long, flags,
1814                unsigned long, new_addr)
1815{
1816        unsigned long ret;
1817
1818        down_write(&current->mm->mmap_sem);
1819        ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1820        up_write(&current->mm->mmap_sem);
1821        return ret;
1822}
1823
1824struct page *follow_page_mask(struct vm_area_struct *vma,
1825                              unsigned long address, unsigned int flags,
1826                              unsigned int *page_mask)
1827{
1828        *page_mask = 0;
1829        return NULL;
1830}
1831
1832int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1833                unsigned long pfn, unsigned long size, pgprot_t prot)
1834{
1835        if (addr != (pfn << PAGE_SHIFT))
1836                return -EINVAL;
1837
1838        vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1839        return 0;
1840}
1841EXPORT_SYMBOL(remap_pfn_range);
1842
1843int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1844{
1845        unsigned long pfn = start >> PAGE_SHIFT;
1846        unsigned long vm_len = vma->vm_end - vma->vm_start;
1847
1848        pfn += vma->vm_pgoff;
1849        return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1850}
1851EXPORT_SYMBOL(vm_iomap_memory);
1852
1853int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1854                        unsigned long pgoff)
1855{
1856        unsigned int size = vma->vm_end - vma->vm_start;
1857
1858        if (!(vma->vm_flags & VM_USERMAP))
1859                return -EINVAL;
1860
1861        vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1862        vma->vm_end = vma->vm_start + size;
1863
1864        return 0;
1865}
1866EXPORT_SYMBOL(remap_vmalloc_range);
1867
1868unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1869        unsigned long len, unsigned long pgoff, unsigned long flags)
1870{
1871        return -ENOMEM;
1872}
1873
1874void unmap_mapping_range(struct address_space *mapping,
1875                         loff_t const holebegin, loff_t const holelen,
1876                         int even_cows)
1877{
1878}
1879EXPORT_SYMBOL(unmap_mapping_range);
1880
1881/*
1882 * Check that a process has enough memory to allocate a new virtual
1883 * mapping. 0 means there is enough memory for the allocation to
1884 * succeed and -ENOMEM implies there is not.
1885 *
1886 * We currently support three overcommit policies, which are set via the
1887 * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1888 *
1889 * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1890 * Additional code 2002 Jul 20 by Robert Love.
1891 *
1892 * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1893 *
1894 * Note this is a helper function intended to be used by LSMs which
1895 * wish to use this logic.
1896 */
1897int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1898{
1899        unsigned long free, allowed, reserve;
1900
1901        vm_acct_memory(pages);
1902
1903        /*
1904         * Sometimes we want to use more memory than we have
1905         */
1906        if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1907                return 0;
1908
1909        if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1910                free = global_page_state(NR_FREE_PAGES);
1911                free += global_page_state(NR_FILE_PAGES);
1912
1913                /*
1914                 * shmem pages shouldn't be counted as free in this
1915                 * case, they can't be purged, only swapped out, and
1916                 * that won't affect the overall amount of available
1917                 * memory in the system.
1918                 */
1919                free -= global_page_state(NR_SHMEM);
1920
1921                free += get_nr_swap_pages();
1922
1923                /*
1924                 * Any slabs which are created with the
1925                 * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1926                 * which are reclaimable, under pressure.  The dentry
1927                 * cache and most inode caches should fall into this
1928                 */
1929                free += global_page_state(NR_SLAB_RECLAIMABLE);
1930
1931                /*
1932                 * Leave reserved pages. The pages are not for anonymous pages.
1933                 */
1934                if (free <= totalreserve_pages)
1935                        goto error;
1936                else
1937                        free -= totalreserve_pages;
1938
1939                /*
1940                 * Reserve some for root
1941                 */
1942                if (!cap_sys_admin)
1943                        free -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
1944
1945                if (free > pages)
1946                        return 0;
1947
1948                goto error;
1949        }
1950
1951        allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1952        /*
1953         * Reserve some 3% for root
1954         */
1955        if (!cap_sys_admin)
1956                allowed -= sysctl_admin_reserve_kbytes >> (PAGE_SHIFT - 10);
1957        allowed += total_swap_pages;
1958
1959        /*
1960         * Don't let a single process grow so big a user can't recover
1961         */
1962        if (mm) {
1963                reserve = sysctl_user_reserve_kbytes >> (PAGE_SHIFT - 10);
1964                allowed -= min(mm->total_vm / 32, reserve);
1965        }
1966
1967        if (percpu_counter_read_positive(&vm_committed_as) < allowed)
1968                return 0;
1969
1970error:
1971        vm_unacct_memory(pages);
1972
1973        return -ENOMEM;
1974}
1975
1976int in_gate_area_no_mm(unsigned long addr)
1977{
1978        return 0;
1979}
1980
1981int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1982{
1983        BUG();
1984        return 0;
1985}
1986EXPORT_SYMBOL(filemap_fault);
1987
1988int generic_file_remap_pages(struct vm_area_struct *vma, unsigned long addr,
1989                             unsigned long size, pgoff_t pgoff)
1990{
1991        BUG();
1992        return 0;
1993}
1994EXPORT_SYMBOL(generic_file_remap_pages);
1995
1996static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
1997                unsigned long addr, void *buf, int len, int write)
1998{
1999        struct vm_area_struct *vma;
2000
2001        down_read(&mm->mmap_sem);
2002
2003        /* the access must start within one of the target process's mappings */
2004        vma = find_vma(mm, addr);
2005        if (vma) {
2006                /* don't overrun this mapping */
2007                if (addr + len >= vma->vm_end)
2008                        len = vma->vm_end - addr;
2009
2010                /* only read or write mappings where it is permitted */
2011                if (write && vma->vm_flags & VM_MAYWRITE)
2012                        copy_to_user_page(vma, NULL, addr,
2013                                         (void *) addr, buf, len);
2014                else if (!write && vma->vm_flags & VM_MAYREAD)
2015                        copy_from_user_page(vma, NULL, addr,
2016                                            buf, (void *) addr, len);
2017                else
2018                        len = 0;
2019        } else {
2020                len = 0;
2021        }
2022
2023        up_read(&mm->mmap_sem);
2024
2025        return len;
2026}
2027
2028/**
2029 * @access_remote_vm - access another process' address space
2030 * @mm:         the mm_struct of the target address space
2031 * @addr:       start address to access
2032 * @buf:        source or destination buffer
2033 * @len:        number of bytes to transfer
2034 * @write:      whether the access is a write
2035 *
2036 * The caller must hold a reference on @mm.
2037 */
2038int access_remote_vm(struct mm_struct *mm, unsigned long addr,
2039                void *buf, int len, int write)
2040{
2041        return __access_remote_vm(NULL, mm, addr, buf, len, write);
2042}
2043
2044/*
2045 * Access another process' address space.
2046 * - source/target buffer must be kernel space
2047 */
2048int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
2049{
2050        struct mm_struct *mm;
2051
2052        if (addr + len < addr)
2053                return 0;
2054
2055        mm = get_task_mm(tsk);
2056        if (!mm)
2057                return 0;
2058
2059        len = __access_remote_vm(tsk, mm, addr, buf, len, write);
2060
2061        mmput(mm);
2062        return len;
2063}
2064
2065/**
2066 * nommu_shrink_inode_mappings - Shrink the shared mappings on an inode
2067 * @inode: The inode to check
2068 * @size: The current filesize of the inode
2069 * @newsize: The proposed filesize of the inode
2070 *
2071 * Check the shared mappings on an inode on behalf of a shrinking truncate to
2072 * make sure that that any outstanding VMAs aren't broken and then shrink the
2073 * vm_regions that extend that beyond so that do_mmap_pgoff() doesn't
2074 * automatically grant mappings that are too large.
2075 */
2076int nommu_shrink_inode_mappings(struct inode *inode, size_t size,
2077                                size_t newsize)
2078{
2079        struct vm_area_struct *vma;
2080        struct vm_region *region;
2081        pgoff_t low, high;
2082        size_t r_size, r_top;
2083
2084        low = newsize >> PAGE_SHIFT;
2085        high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2086
2087        down_write(&nommu_region_sem);
2088        mutex_lock(&inode->i_mapping->i_mmap_mutex);
2089
2090        /* search for VMAs that fall within the dead zone */
2091        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) {
2092                /* found one - only interested if it's shared out of the page
2093                 * cache */
2094                if (vma->vm_flags & VM_SHARED) {
2095                        mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2096                        up_write(&nommu_region_sem);
2097                        return -ETXTBSY; /* not quite true, but near enough */
2098                }
2099        }
2100
2101        /* reduce any regions that overlap the dead zone - if in existence,
2102         * these will be pointed to by VMAs that don't overlap the dead zone
2103         *
2104         * we don't check for any regions that start beyond the EOF as there
2105         * shouldn't be any
2106         */
2107        vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap,
2108                                  0, ULONG_MAX) {
2109                if (!(vma->vm_flags & VM_SHARED))
2110                        continue;
2111
2112                region = vma->vm_region;
2113                r_size = region->vm_top - region->vm_start;
2114                r_top = (region->vm_pgoff << PAGE_SHIFT) + r_size;
2115
2116                if (r_top > newsize) {
2117                        region->vm_top -= r_top - newsize;
2118                        if (region->vm_end > region->vm_top)
2119                                region->vm_end = region->vm_top;
2120                }
2121        }
2122
2123        mutex_unlock(&inode->i_mapping->i_mmap_mutex);
2124        up_write(&nommu_region_sem);
2125        return 0;
2126}
2127
2128/*
2129 * Initialise sysctl_user_reserve_kbytes.
2130 *
2131 * This is intended to prevent a user from starting a single memory hogging
2132 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
2133 * mode.
2134 *
2135 * The default value is min(3% of free memory, 128MB)
2136 * 128MB is enough to recover with sshd/login, bash, and top/kill.
2137 */
2138static int __meminit init_user_reserve(void)
2139{
2140        unsigned long free_kbytes;
2141
2142        free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
2143
2144        sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
2145        return 0;
2146}
2147module_init(init_user_reserve)
2148
2149/*
2150 * Initialise sysctl_admin_reserve_kbytes.
2151 *
2152 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
2153 * to log in and kill a memory hogging process.
2154 *
2155 * Systems with more than 256MB will reserve 8MB, enough to recover
2156 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
2157 * only reserve 3% of free pages by default.
2158 */
2159static int __meminit init_admin_reserve(void)
2160{
2161        unsigned long free_kbytes;
2162
2163        free_kbytes = global_page_state(NR_FREE_PAGES) << (PAGE_SHIFT - 10);
2164
2165        sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
2166        return 0;
2167}
2168module_init(init_admin_reserve)
2169
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.