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