mm/nommu.c

   1 /*
   2  *  linux/mm/nommu.c
   3  *
   4  *  Replacement code for mm functions to support CPU's that don't
   5  *  have any form of memory management unit (thus no virtual memory).
   6  *
   7  *  See Documentation/nommu-mmap.txt
   8  *
   9  *  Copyright (c) 2004-2005 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      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/ptrace.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
  37 void *high_memory;
  38 struct page *mem_map;
  39 unsigned long max_mapnr;
  40 unsigned long num_physpages;
  41 unsigned long askedalloc, realalloc;
  42 atomic_long_t vm_committed_space = ATOMIC_LONG_INIT(0);
  43 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  44 int sysctl_overcommit_ratio = 50; /* default is 50% */
  45 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  46 int heap_stack_gap = 0;
  47
  48 EXPORT_SYMBOL(mem_map);
  49 EXPORT_SYMBOL(num_physpages);
  50
  51 /* list of shareable VMAs */
  52 struct rb_root nommu_vma_tree = RB_ROOT;
  53 DECLARE_RWSEM(nommu_vma_sem);
  54
  55 struct vm_operations_struct generic_file_vm_ops = {
  56 };
  57
  58 /*
  59  * Handle all mappings that got truncated by a "truncate()"
  60  * system call.
  61  *
  62  * NOTE! We have to be ready to update the memory sharing
  63  * between the file and the memory map for a potential last
  64  * incomplete page.  Ugly, but necessary.
  65  */
  66 int vmtruncate(struct inode *inode, loff_t offset)
  67 {
  68         struct address_space *mapping = inode->i_mapping;
  69         unsigned long limit;
  70
  71         if (inode->i_size < offset)
  72                 goto do_expand;
  73         i_size_write(inode, offset);
  74
  75         truncate_inode_pages(mapping, offset);
  76         goto out_truncate;
  77
  78 do_expand:
  79         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
  80         if (limit != RLIM_INFINITY && offset > limit)
  81                 goto out_sig;
  82         if (offset > inode->i_sb->s_maxbytes)
  83                 goto out;
  84         i_size_write(inode, offset);
  85
  86 out_truncate:
  87         if (inode->i_op && inode->i_op->truncate)
  88                 inode->i_op->truncate(inode);
  89         return 0;
  90 out_sig:
  91         send_sig(SIGXFSZ, current, 0);
  92 out:
  93         return -EFBIG;
  94 }
  95
  96 EXPORT_SYMBOL(vmtruncate);
  97
  98 /*
  99  * Return the total memory allocated for this pointer, not
 100  * just what the caller asked for.
 101  *
 102  * Doesn't have to be accurate, i.e. may have races.
 103  */
 104 unsigned int kobjsize(const void *objp)
 105 {
 106         struct page *page;
 107         int order = 0;
 108
 109         /*
 110          * If the object we have should not have ksize performed on it,
 111          * return size of 0
 112          */
 113         if (!objp)
 114                 return 0;
 115
 116         if ((unsigned long)objp >= memory_end)
 117                 return 0;
 118
 119         page = virt_to_head_page(objp);
 120         if (!page)
 121                 return 0;
 122
 123         /*
 124          * If the allocator sets PageSlab, we know the pointer came from
 125          * kmalloc().
 126          */
 127         if (PageSlab(page))
 128                 return ksize(objp);
 129
 130         /*
 131          * The ksize() function is only guaranteed to work for pointers
 132          * returned by kmalloc(). So handle arbitrary pointers, that we expect
 133          * always to be compound pages, here.
 134          */
 135         if (PageCompound(page))
 136                 order = compound_order(page);
 137
 138         /*
 139          * Finally, handle arbitrary pointers that don't set PageSlab.
 140          * Default to 0-order in the case when we're unable to ksize()
 141          * the object.
 142          */
 143         return PAGE_SIZE << order;
 144 }
 145
 146 /*
 147  * get a list of pages in an address range belonging to the specified process
 148  * and indicate the VMA that covers each page
 149  * - this is potentially dodgy as we may end incrementing the page count of a
 150  *   slab page or a secondary page from a compound page
 151  * - don't permit access to VMAs that don't support it, such as I/O mappings
 152  */
 153 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 154         unsigned long start, int len, int write, int force,
 155         struct page **pages, struct vm_area_struct **vmas)
 156 {
 157         struct vm_area_struct *vma;
 158         unsigned long vm_flags;
 159         int i;
 160
 161         /* calculate required read or write permissions.
 162          * - if 'force' is set, we only require the "MAY" flags.
 163          */
 164         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 165         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 166
 167         for (i = 0; i < len; i++) {
 168                 vma = find_vma(mm, start);
 169                 if (!vma)
 170                         goto finish_or_fault;
 171
 172                 /* protect what we can, including chardevs */
 173                 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
 174                     !(vm_flags & vma->vm_flags))
 175                         goto finish_or_fault;
 176
 177                 if (pages) {
 178                         pages[i] = virt_to_page(start);
 179                         if (pages[i])
 180                                 page_cache_get(pages[i]);
 181                 }
 182                 if (vmas)
 183                         vmas[i] = vma;
 184                 start += PAGE_SIZE;
 185         }
 186
 187         return i;
 188
 189 finish_or_fault:
 190         return i ? : -EFAULT;
 191 }
 192 EXPORT_SYMBOL(get_user_pages);
 193
 194 DEFINE_RWLOCK(vmlist_lock);
 195 struct vm_struct *vmlist;
 196
 197 void vfree(const void *addr)
 198 {
 199         kfree(addr);
 200 }
 201 EXPORT_SYMBOL(vfree);
 202
 203 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 204 {
 205         /*
 206          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 207          * returns only a logical address.
 208          */
 209         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 210 }
 211 EXPORT_SYMBOL(__vmalloc);
 212
 213 void *vmalloc_user(unsigned long size)
 214 {
 215         void *ret;
 216
 217         ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
 218                         PAGE_KERNEL);
 219         if (ret) {
 220                 struct vm_area_struct *vma;
 221
 222                 down_write(&current->mm->mmap_sem);
 223                 vma = find_vma(current->mm, (unsigned long)ret);
 224                 if (vma)
 225                         vma->vm_flags |= VM_USERMAP;
 226                 up_write(&current->mm->mmap_sem);
 227         }
 228
 229         return ret;
 230 }
 231 EXPORT_SYMBOL(vmalloc_user);
 232
 233 struct page *vmalloc_to_page(const void *addr)
 234 {
 235         return virt_to_page(addr);
 236 }
 237 EXPORT_SYMBOL(vmalloc_to_page);
 238
 239 unsigned long vmalloc_to_pfn(const void *addr)
 240 {
 241         return page_to_pfn(virt_to_page(addr));
 242 }
 243 EXPORT_SYMBOL(vmalloc_to_pfn);
 244
 245 long vread(char *buf, char *addr, unsigned long count)
 246 {
 247         memcpy(buf, addr, count);
 248         return count;
 249 }
 250
 251 long vwrite(char *buf, char *addr, unsigned long count)
 252 {
 253         /* Don't allow overflow */
 254         if ((unsigned long) addr + count < count)
 255                 count = -(unsigned long) addr;
 256
 257         memcpy(addr, buf, count);
 258         return(count);
 259 }
 260
 261 /*
 262  *      vmalloc  -  allocate virtually continguos memory
 263  *
 264  *      @size:          allocation size
 265  *
 266  *      Allocate enough pages to cover @size from the page level
 267  *      allocator and map them into continguos kernel virtual space.
 268  *
 269  *      For tight control over page level allocator and protection flags
 270  *      use __vmalloc() instead.
 271  */
 272 void *vmalloc(unsigned long size)
 273 {
 274        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 275 }
 276 EXPORT_SYMBOL(vmalloc);
 277
 278 void *vmalloc_node(unsigned long size, int node)
 279 {
 280         return vmalloc(size);
 281 }
 282 EXPORT_SYMBOL(vmalloc_node);
 283
 284 /**
 285  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 286  *      @size:          allocation size
 287  *
 288  *      Allocate enough 32bit PA addressable pages to cover @size from the
 289  *      page level allocator and map them into continguos kernel virtual space.
 290  */
 291 void *vmalloc_32(unsigned long size)
 292 {
 293         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 294 }
 295 EXPORT_SYMBOL(vmalloc_32);
 296
 297 /**
 298  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 299  *      @size:          allocation size
 300  *
 301  * The resulting memory area is 32bit addressable and zeroed so it can be
 302  * mapped to userspace without leaking data.
 303  *
 304  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 305  * remap_vmalloc_range() are permissible.
 306  */
 307 void *vmalloc_32_user(unsigned long size)
 308 {
 309         /*
 310          * We'll have to sort out the ZONE_DMA bits for 64-bit,
 311          * but for now this can simply use vmalloc_user() directly.
 312          */
 313         return vmalloc_user(size);
 314 }
 315 EXPORT_SYMBOL(vmalloc_32_user);
 316
 317 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 318 {
 319         BUG();
 320         return NULL;
 321 }
 322 EXPORT_SYMBOL(vmap);
 323
 324 void vunmap(const void *addr)
 325 {
 326         BUG();
 327 }
 328 EXPORT_SYMBOL(vunmap);
 329
 330 /*
 331  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 332  * have one.
 333  */
 334 void  __attribute__((weak)) vmalloc_sync_all(void)
 335 {
 336 }
 337
 338 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 339                    struct page *page)
 340 {
 341         return -EINVAL;
 342 }
 343 EXPORT_SYMBOL(vm_insert_page);
 344
 345 /*
 346  *  sys_brk() for the most part doesn't need the global kernel
 347  *  lock, except when an application is doing something nasty
 348  *  like trying to un-brk an area that has already been mapped
 349  *  to a regular file.  in this case, the unmapping will need
 350  *  to invoke file system routines that need the global lock.
 351  */
 352 asmlinkage unsigned long sys_brk(unsigned long brk)
 353 {
 354         struct mm_struct *mm = current->mm;
 355
 356         if (brk < mm->start_brk || brk > mm->context.end_brk)
 357                 return mm->brk;
 358
 359         if (mm->brk == brk)
 360                 return mm->brk;
 361
 362         /*
 363          * Always allow shrinking brk
 364          */
 365         if (brk <= mm->brk) {
 366                 mm->brk = brk;
 367                 return brk;
 368         }
 369
 370         /*
 371          * Ok, looks good - let it rip.
 372          */
 373         return mm->brk = brk;
 374 }
 375
 376 #ifdef DEBUG
 377 static void show_process_blocks(void)
 378 {
 379         struct vm_list_struct *vml;
 380
 381         printk("Process blocks %d:", current->pid);
 382
 383         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
 384                 printk(" %p: %p", vml, vml->vma);
 385                 if (vml->vma)
 386                         printk(" (%d @%lx #%d)",
 387                                kobjsize((void *) vml->vma->vm_start),
 388                                vml->vma->vm_start,
 389                                atomic_read(&vml->vma->vm_usage));
 390                 printk(vml->next ? " ->" : ".\n");
 391         }
 392 }
 393 #endif /* DEBUG */
 394
 395 /*
 396  * add a VMA into a process's mm_struct in the appropriate place in the list
 397  * - should be called with mm->mmap_sem held writelocked
 398  */
 399 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
 400 {
 401         struct vm_list_struct **ppv;
 402
 403         for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
 404                 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
 405                         break;
 406
 407         vml->next = *ppv;
 408         *ppv = vml;
 409 }
 410
 411 /*
 412  * look up the first VMA in which addr resides, NULL if none
 413  * - should be called with mm->mmap_sem at least held readlocked
 414  */
 415 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 416 {
 417         struct vm_list_struct *loop, *vml;
 418
 419         /* search the vm_start ordered list */
 420         vml = NULL;
 421         for (loop = mm->context.vmlist; loop; loop = loop->next) {
 422                 if (loop->vma->vm_start > addr)
 423                         break;
 424                 vml = loop;
 425         }
 426
 427         if (vml && vml->vma->vm_end > addr)
 428                 return vml->vma;
 429
 430         return NULL;
 431 }
 432 EXPORT_SYMBOL(find_vma);
 433
 434 /*
 435  * find a VMA
 436  * - we don't extend stack VMAs under NOMMU conditions
 437  */
 438 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 439 {
 440         return find_vma(mm, addr);
 441 }
 442
 443 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 444 {
 445         return -ENOMEM;
 446 }
 447
 448 /*
 449  * look up the first VMA exactly that exactly matches addr
 450  * - should be called with mm->mmap_sem at least held readlocked
 451  */
 452 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 453                                                     unsigned long addr)
 454 {
 455         struct vm_list_struct *vml;
 456
 457         /* search the vm_start ordered list */
 458         for (vml = mm->context.vmlist; vml; vml = vml->next) {
 459                 if (vml->vma->vm_start == addr)
 460                         return vml->vma;
 461                 if (vml->vma->vm_start > addr)
 462                         break;
 463         }
 464
 465         return NULL;
 466 }
 467
 468 /*
 469  * find a VMA in the global tree
 470  */
 471 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
 472 {
 473         struct vm_area_struct *vma;
 474         struct rb_node *n = nommu_vma_tree.rb_node;
 475
 476         while (n) {
 477                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 478
 479                 if (start < vma->vm_start)
 480                         n = n->rb_left;
 481                 else if (start > vma->vm_start)
 482                         n = n->rb_right;
 483                 else
 484                         return vma;
 485         }
 486
 487         return NULL;
 488 }
 489
 490 /*
 491  * add a VMA in the global tree
 492  */
 493 static void add_nommu_vma(struct vm_area_struct *vma)
 494 {
 495         struct vm_area_struct *pvma;
 496         struct address_space *mapping;
 497         struct rb_node **p = &nommu_vma_tree.rb_node;
 498         struct rb_node *parent = NULL;
 499
 500         /* add the VMA to the mapping */
 501         if (vma->vm_file) {
 502                 mapping = vma->vm_file->f_mapping;
 503
 504                 flush_dcache_mmap_lock(mapping);
 505                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 506                 flush_dcache_mmap_unlock(mapping);
 507         }
 508
 509         /* add the VMA to the master list */
 510         while (*p) {
 511                 parent = *p;
 512                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 513
 514                 if (vma->vm_start < pvma->vm_start) {
 515                         p = &(*p)->rb_left;
 516                 }
 517                 else if (vma->vm_start > pvma->vm_start) {
 518                         p = &(*p)->rb_right;
 519                 }
 520                 else {
 521                         /* mappings are at the same address - this can only
 522                          * happen for shared-mem chardevs and shared file
 523                          * mappings backed by ramfs/tmpfs */
 524                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
 525
 526                         if (vma < pvma)
 527                                 p = &(*p)->rb_left;
 528                         else if (vma > pvma)
 529                                 p = &(*p)->rb_right;
 530                         else
 531                                 BUG();
 532                 }
 533         }
 534
 535         rb_link_node(&vma->vm_rb, parent, p);
 536         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
 537 }
 538
 539 /*
 540  * delete a VMA from the global list
 541  */
 542 static void delete_nommu_vma(struct vm_area_struct *vma)
 543 {
 544         struct address_space *mapping;
 545
 546         /* remove the VMA from the mapping */
 547         if (vma->vm_file) {
 548                 mapping = vma->vm_file->f_mapping;
 549
 550                 flush_dcache_mmap_lock(mapping);
 551                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 552                 flush_dcache_mmap_unlock(mapping);
 553         }
 554
 555         /* remove from the master list */
 556         rb_erase(&vma->vm_rb, &nommu_vma_tree);
 557 }
 558
 559 /*
 560  * determine whether a mapping should be permitted and, if so, what sort of
 561  * mapping we're capable of supporting
 562  */
 563 static int validate_mmap_request(struct file *file,
 564                                  unsigned long addr,
 565                                  unsigned long len,
 566                                  unsigned long prot,
 567                                  unsigned long flags,
 568                                  unsigned long pgoff,
 569                                  unsigned long *_capabilities)
 570 {
 571         unsigned long capabilities;
 572         unsigned long reqprot = prot;
 573         int ret;
 574
 575         /* do the simple checks first */
 576         if (flags & MAP_FIXED || addr) {
 577                 printk(KERN_DEBUG
 578                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 579                        current->pid);
 580                 return -EINVAL;
 581         }
 582
 583         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 584             (flags & MAP_TYPE) != MAP_SHARED)
 585                 return -EINVAL;
 586
 587         if (!len)
 588                 return -EINVAL;
 589
 590         /* Careful about overflows.. */
 591         len = PAGE_ALIGN(len);
 592         if (!len || len > TASK_SIZE)
 593                 return -ENOMEM;
 594
 595         /* offset overflow? */
 596         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 597                 return -EOVERFLOW;
 598
 599         if (file) {
 600                 /* validate file mapping requests */
 601                 struct address_space *mapping;
 602
 603                 /* files must support mmap */
 604                 if (!file->f_op || !file->f_op->mmap)
 605                         return -ENODEV;
 606
 607                 /* work out if what we've got could possibly be shared
 608                  * - we support chardevs that provide their own "memory"
 609                  * - we support files/blockdevs that are memory backed
 610                  */
 611                 mapping = file->f_mapping;
 612                 if (!mapping)
 613                         mapping = file->f_path.dentry->d_inode->i_mapping;
 614
 615                 capabilities = 0;
 616                 if (mapping && mapping->backing_dev_info)
 617                         capabilities = mapping->backing_dev_info->capabilities;
 618
 619                 if (!capabilities) {
 620                         /* no explicit capabilities set, so assume some
 621                          * defaults */
 622                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
 623                         case S_IFREG:
 624                         case S_IFBLK:
 625                                 capabilities = BDI_CAP_MAP_COPY;
 626                                 break;
 627
 628                         case S_IFCHR:
 629                                 capabilities =
 630                                         BDI_CAP_MAP_DIRECT |
 631                                         BDI_CAP_READ_MAP |
 632                                         BDI_CAP_WRITE_MAP;
 633                                 break;
 634
 635                         default:
 636                                 return -EINVAL;
 637                         }
 638                 }
 639
 640                 /* eliminate any capabilities that we can't support on this
 641                  * device */
 642                 if (!file->f_op->get_unmapped_area)
 643                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 644                 if (!file->f_op->read)
 645                         capabilities &= ~BDI_CAP_MAP_COPY;
 646
 647                 if (flags & MAP_SHARED) {
 648                         /* do checks for writing, appending and locking */
 649                         if ((prot & PROT_WRITE) &&
 650                             !(file->f_mode & FMODE_WRITE))
 651                                 return -EACCES;
 652
 653                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
 654                             (file->f_mode & FMODE_WRITE))
 655                                 return -EACCES;
 656
 657                         if (locks_verify_locked(file->f_path.dentry->d_inode))
 658                                 return -EAGAIN;
 659
 660                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 661                                 return -ENODEV;
 662
 663                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
 664                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
 665                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
 666                             ) {
 667                                 printk("MAP_SHARED not completely supported on !MMU\n");
 668                                 return -EINVAL;
 669                         }
 670
 671                         /* we mustn't privatise shared mappings */
 672                         capabilities &= ~BDI_CAP_MAP_COPY;
 673                 }
 674                 else {
 675                         /* we're going to read the file into private memory we
 676                          * allocate */
 677                         if (!(capabilities & BDI_CAP_MAP_COPY))
 678                                 return -ENODEV;
 679
 680                         /* we don't permit a private writable mapping to be
 681                          * shared with the backing device */
 682                         if (prot & PROT_WRITE)
 683                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 684                 }
 685
 686                 /* handle executable mappings and implied executable
 687                  * mappings */
 688                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
 689                         if (prot & PROT_EXEC)
 690                                 return -EPERM;
 691                 }
 692                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 693                         /* handle implication of PROT_EXEC by PROT_READ */
 694                         if (current->personality & READ_IMPLIES_EXEC) {
 695                                 if (capabilities & BDI_CAP_EXEC_MAP)
 696                                         prot |= PROT_EXEC;
 697                         }
 698                 }
 699                 else if ((prot & PROT_READ) &&
 700                          (prot & PROT_EXEC) &&
 701                          !(capabilities & BDI_CAP_EXEC_MAP)
 702                          ) {
 703                         /* backing file is not executable, try to copy */
 704                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 705                 }
 706         }
 707         else {
 708                 /* anonymous mappings are always memory backed and can be
 709                  * privately mapped
 710                  */
 711                 capabilities = BDI_CAP_MAP_COPY;
 712
 713                 /* handle PROT_EXEC implication by PROT_READ */
 714                 if ((prot & PROT_READ) &&
 715                     (current->personality & READ_IMPLIES_EXEC))
 716                         prot |= PROT_EXEC;
 717         }
 718
 719         /* allow the security API to have its say */
 720         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
 721         if (ret < 0)
 722                 return ret;
 723
 724         /* looks okay */
 725         *_capabilities = capabilities;
 726         return 0;
 727 }
 728
 729 /*
 730  * we've determined that we can make the mapping, now translate what we
 731  * now know into VMA flags
 732  */
 733 static unsigned long determine_vm_flags(struct file *file,
 734                                         unsigned long prot,
 735                                         unsigned long flags,
 736                                         unsigned long capabilities)
 737 {
 738         unsigned long vm_flags;
 739
 740         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
 741         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 742         /* vm_flags |= mm->def_flags; */
 743
 744         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
 745                 /* attempt to share read-only copies of mapped file chunks */
 746                 if (file && !(prot & PROT_WRITE))
 747                         vm_flags |= VM_MAYSHARE;
 748         }
 749         else {
 750                 /* overlay a shareable mapping on the backing device or inode
 751                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 752                  * romfs/cramfs */
 753                 if (flags & MAP_SHARED)
 754                         vm_flags |= VM_MAYSHARE | VM_SHARED;
 755                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
 756                         vm_flags |= VM_MAYSHARE;
 757         }
 758
 759         /* refuse to let anyone share private mappings with this process if
 760          * it's being traced - otherwise breakpoints set in it may interfere
 761          * with another untraced process
 762          */
 763         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
 764                 vm_flags &= ~VM_MAYSHARE;
 765
 766         return vm_flags;
 767 }
 768
 769 /*
 770  * set up a shared mapping on a file
 771  */
 772 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
 773 {
 774         int ret;
 775
 776         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 777         if (ret != -ENOSYS)
 778                 return ret;
 779
 780         /* getting an ENOSYS error indicates that direct mmap isn't
 781          * possible (as opposed to tried but failed) so we'll fall
 782          * through to making a private copy of the data and mapping
 783          * that if we can */
 784         return -ENODEV;
 785 }
 786
 787 /*
 788  * set up a private mapping or an anonymous shared mapping
 789  */
 790 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
 791 {
 792         void *base;
 793         int ret;
 794
 795         /* invoke the file's mapping function so that it can keep track of
 796          * shared mappings on devices or memory
 797          * - VM_MAYSHARE will be set if it may attempt to share
 798          */
 799         if (vma->vm_file) {
 800                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 801                 if (ret != -ENOSYS) {
 802                         /* shouldn't return success if we're not sharing */
 803                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
 804                         return ret; /* success or a real error */
 805                 }
 806
 807                 /* getting an ENOSYS error indicates that direct mmap isn't
 808                  * possible (as opposed to tried but failed) so we'll try to
 809                  * make a private copy of the data and map that instead */
 810         }
 811
 812         /* allocate some memory to hold the mapping
 813          * - note that this may not return a page-aligned address if the object
 814          *   we're allocating is smaller than a page
 815          */
 816         base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
 817         if (!base)
 818                 goto enomem;
 819
 820         vma->vm_start = (unsigned long) base;
 821         vma->vm_end = vma->vm_start + len;
 822         vma->vm_flags |= VM_MAPPED_COPY;
 823
 824 #ifdef WARN_ON_SLACK
 825         if (len + WARN_ON_SLACK <= kobjsize(result))
 826                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
 827                        len, current->pid, kobjsize(result) - len);
 828 #endif
 829
 830         if (vma->vm_file) {
 831                 /* read the contents of a file into the copy */
 832                 mm_segment_t old_fs;
 833                 loff_t fpos;
 834
 835                 fpos = vma->vm_pgoff;
 836                 fpos <<= PAGE_SHIFT;
 837
 838                 old_fs = get_fs();
 839                 set_fs(KERNEL_DS);
 840                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
 841                 set_fs(old_fs);
 842
 843                 if (ret < 0)
 844                         goto error_free;
 845
 846                 /* clear the last little bit */
 847                 if (ret < len)
 848                         memset(base + ret, 0, len - ret);
 849
 850         } else {
 851                 /* if it's an anonymous mapping, then just clear it */
 852                 memset(base, 0, len);
 853         }
 854
 855         return 0;
 856
 857 error_free:
 858         kfree(base);
 859         vma->vm_start = 0;
 860         return ret;
 861
 862 enomem:
 863         printk("Allocation of length %lu from process %d failed\n",
 864                len, current->pid);
 865         show_free_areas();
 866         return -ENOMEM;
 867 }
 868
 869 /*
 870  * handle mapping creation for uClinux
 871  */
 872 unsigned long do_mmap_pgoff(struct file *file,
 873                             unsigned long addr,
 874                             unsigned long len,
 875                             unsigned long prot,
 876                             unsigned long flags,
 877                             unsigned long pgoff)
 878 {
 879         struct vm_list_struct *vml = NULL;
 880         struct vm_area_struct *vma = NULL;
 881         struct rb_node *rb;
 882         unsigned long capabilities, vm_flags;
 883         void *result;
 884         int ret;
 885
 886         if (!(flags & MAP_FIXED))
 887                 addr = round_hint_to_min(addr);
 888
 889         /* decide whether we should attempt the mapping, and if so what sort of
 890          * mapping */
 891         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
 892                                     &capabilities);
 893         if (ret < 0)
 894                 return ret;
 895
 896         /* we've determined that we can make the mapping, now translate what we
 897          * now know into VMA flags */
 898         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
 899
 900         /* we're going to need to record the mapping if it works */
 901         vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
 902         if (!vml)
 903                 goto error_getting_vml;
 904
 905         down_write(&nommu_vma_sem);
 906
 907         /* if we want to share, we need to check for VMAs created by other
 908          * mmap() calls that overlap with our proposed mapping
 909          * - we can only share with an exact match on most regular files
 910          * - shared mappings on character devices and memory backed files are
 911          *   permitted to overlap inexactly as far as we are concerned for in
 912          *   these cases, sharing is handled in the driver or filesystem rather
 913          *   than here
 914          */
 915         if (vm_flags & VM_MAYSHARE) {
 916                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 917                 unsigned long vmpglen;
 918
 919                 /* suppress VMA sharing for shared regions */
 920                 if (vm_flags & VM_SHARED &&
 921                     capabilities & BDI_CAP_MAP_DIRECT)
 922                         goto dont_share_VMAs;
 923
 924                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
 925                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
 926
 927                         if (!(vma->vm_flags & VM_MAYSHARE))
 928                                 continue;
 929
 930                         /* search for overlapping mappings on the same file */
 931                         if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
 932                                 continue;
 933
 934                         if (vma->vm_pgoff >= pgoff + pglen)
 935                                 continue;
 936
 937                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
 938                         vmpglen >>= PAGE_SHIFT;
 939                         if (pgoff >= vma->vm_pgoff + vmpglen)
 940                                 continue;
 941
 942                         /* handle inexactly overlapping matches between mappings */
 943                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
 944                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
 945                                         goto sharing_violation;
 946                                 continue;
 947                         }
 948
 949                         /* we've found a VMA we can share */
 950                         atomic_inc(&vma->vm_usage);
 951
 952                         vml->vma = vma;
 953                         result = (void *) vma->vm_start;
 954                         goto shared;
 955                 }
 956
 957         dont_share_VMAs:
 958                 vma = NULL;
 959
 960                 /* obtain the address at which to make a shared mapping
 961                  * - this is the hook for quasi-memory character devices to
 962                  *   tell us the location of a shared mapping
 963                  */
 964                 if (file && file->f_op->get_unmapped_area) {
 965                         addr = file->f_op->get_unmapped_area(file, addr, len,
 966                                                              pgoff, flags);
 967                         if (IS_ERR((void *) addr)) {
 968                                 ret = addr;
 969                                 if (ret != (unsigned long) -ENOSYS)
 970                                         goto error;
 971
 972                                 /* the driver refused to tell us where to site
 973                                  * the mapping so we'll have to attempt to copy
 974                                  * it */
 975                                 ret = (unsigned long) -ENODEV;
 976                                 if (!(capabilities & BDI_CAP_MAP_COPY))
 977                                         goto error;
 978
 979                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 980                         }
 981                 }
 982         }
 983
 984         /* we're going to need a VMA struct as well */
 985         vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
 986         if (!vma)
 987                 goto error_getting_vma;
 988
 989         INIT_LIST_HEAD(&vma->anon_vma_node);
 990         atomic_set(&vma->vm_usage, 1);
 991         if (file) {
 992                 get_file(file);
 993                 if (vm_flags & VM_EXECUTABLE) {
 994                         added_exe_file_vma(current->mm);
 995                         vma->vm_mm = current->mm;
 996                 }
 997         }
 998         vma->vm_file    = file;
 999         vma->vm_flags   = vm_flags;
1000         vma->vm_start   = addr;
1001         vma->vm_end     = addr + len;
1002         vma->vm_pgoff   = pgoff;
1003
1004         vml->vma = vma;
1005
1006         /* set up the mapping */
1007         if (file && vma->vm_flags & VM_SHARED)
1008                 ret = do_mmap_shared_file(vma, len);
1009         else
1010                 ret = do_mmap_private(vma, len);
1011         if (ret < 0)
1012                 goto error;
1013
1014         /* okay... we have a mapping; now we have to register it */
1015         result = (void *) vma->vm_start;
1016
1017         if (vma->vm_flags & VM_MAPPED_COPY) {
1018                 realalloc += kobjsize(result);
1019                 askedalloc += len;
1020         }
1021
1022         realalloc += kobjsize(vma);
1023         askedalloc += sizeof(*vma);
1024
1025         current->mm->total_vm += len >> PAGE_SHIFT;
1026
1027         add_nommu_vma(vma);
1028
1029  shared:
1030         realalloc += kobjsize(vml);
1031         askedalloc += sizeof(*vml);
1032
1033         add_vma_to_mm(current->mm, vml);
1034
1035         up_write(&nommu_vma_sem);
1036
1037         if (prot & PROT_EXEC)
1038                 flush_icache_range((unsigned long) result,
1039                                    (unsigned long) result + len);
1040
1041 #ifdef DEBUG
1042         printk("do_mmap:\n");
1043         show_process_blocks();
1044 #endif
1045
1046         return (unsigned long) result;
1047
1048  error:
1049         up_write(&nommu_vma_sem);
1050         kfree(vml);
1051         if (vma) {
1052                 if (vma->vm_file) {
1053                         fput(vma->vm_file);
1054                         if (vma->vm_flags & VM_EXECUTABLE)
1055                                 removed_exe_file_vma(vma->vm_mm);
1056                 }
1057                 kfree(vma);
1058         }
1059         return ret;
1060
1061  sharing_violation:
1062         up_write(&nommu_vma_sem);
1063         printk("Attempt to share mismatched mappings\n");
1064         kfree(vml);
1065         return -EINVAL;
1066
1067  error_getting_vma:
1068         up_write(&nommu_vma_sem);
1069         kfree(vml);
1070         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
1071                len, current->pid);
1072         show_free_areas();
1073         return -ENOMEM;
1074
1075  error_getting_vml:
1076         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
1077                len, current->pid);
1078         show_free_areas();
1079         return -ENOMEM;
1080 }
1081 EXPORT_SYMBOL(do_mmap_pgoff);
1082
1083 /*
1084  * handle mapping disposal for uClinux
1085  */
1086 static void put_vma(struct mm_struct *mm, struct vm_area_struct *vma)
1087 {
1088         if (vma) {
1089                 down_write(&nommu_vma_sem);
1090
1091                 if (atomic_dec_and_test(&vma->vm_usage)) {
1092                         delete_nommu_vma(vma);
1093
1094                         if (vma->vm_ops && vma->vm_ops->close)
1095                                 vma->vm_ops->close(vma);
1096
1097                         /* IO memory and memory shared directly out of the pagecache from
1098                          * ramfs/tmpfs mustn't be released here */
1099                         if (vma->vm_flags & VM_MAPPED_COPY) {
1100                                 realalloc -= kobjsize((void *) vma->vm_start);
1101                                 askedalloc -= vma->vm_end - vma->vm_start;
1102                                 kfree((void *) vma->vm_start);
1103                         }
1104
1105                         realalloc -= kobjsize(vma);
1106                         askedalloc -= sizeof(*vma);
1107
1108                         if (vma->vm_file) {
1109                                 fput(vma->vm_file);
1110                                 if (vma->vm_flags & VM_EXECUTABLE)
1111                                         removed_exe_file_vma(mm);
1112                         }
1113                         kfree(vma);
1114                 }
1115
1116                 up_write(&nommu_vma_sem);
1117         }
1118 }
1119
1120 /*
1121  * release a mapping
1122  * - under NOMMU conditions the parameters must match exactly to the mapping to
1123  *   be removed
1124  */
1125 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1126 {
1127         struct vm_list_struct *vml, **parent;
1128         unsigned long end = addr + len;
1129
1130 #ifdef DEBUG
1131         printk("do_munmap:\n");
1132 #endif
1133
1134         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1135                 if ((*parent)->vma->vm_start > addr)
1136                         break;
1137                 if ((*parent)->vma->vm_start == addr &&
1138                     ((len == 0) || ((*parent)->vma->vm_end == end)))
1139                         goto found;
1140         }
1141
1142         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1143                current->pid, current->comm, (void *) addr);
1144         return -EINVAL;
1145
1146  found:
1147         vml = *parent;
1148
1149         put_vma(mm, vml->vma);
1150
1151         *parent = vml->next;
1152         realalloc -= kobjsize(vml);
1153         askedalloc -= sizeof(*vml);
1154         kfree(vml);
1155
1156         update_hiwater_vm(mm);
1157         mm->total_vm -= len >> PAGE_SHIFT;
1158
1159 #ifdef DEBUG
1160         show_process_blocks();
1161 #endif
1162
1163         return 0;
1164 }
1165 EXPORT_SYMBOL(do_munmap);
1166
1167 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1168 {
1169         int ret;
1170         struct mm_struct *mm = current->mm;
1171
1172         down_write(&mm->mmap_sem);
1173         ret = do_munmap(mm, addr, len);
1174         up_write(&mm->mmap_sem);
1175         return ret;
1176 }
1177
1178 /*
1179  * Release all mappings
1180  */
1181 void exit_mmap(struct mm_struct * mm)
1182 {
1183         struct vm_list_struct *tmp;
1184
1185         if (mm) {
1186 #ifdef DEBUG
1187                 printk("Exit_mmap:\n");
1188 #endif
1189
1190                 mm->total_vm = 0;
1191
1192                 while ((tmp = mm->context.vmlist)) {
1193                         mm->context.vmlist = tmp->next;
1194                         put_vma(mm, tmp->vma);
1195
1196                         realalloc -= kobjsize(tmp);
1197                         askedalloc -= sizeof(*tmp);
1198                         kfree(tmp);
1199                 }
1200
1201 #ifdef DEBUG
1202                 show_process_blocks();
1203 #endif
1204         }
1205 }
1206
1207 unsigned long do_brk(unsigned long addr, unsigned long len)
1208 {
1209         return -ENOMEM;
1210 }
1211
1212 /*
1213  * expand (or shrink) an existing mapping, potentially moving it at the same
1214  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1215  *
1216  * under NOMMU conditions, we only permit changing a mapping's size, and only
1217  * as long as it stays within the hole allocated by the kmalloc() call in
1218  * do_mmap_pgoff() and the block is not shareable
1219  *
1220  * MREMAP_FIXED is not supported under NOMMU conditions
1221  */
1222 unsigned long do_mremap(unsigned long addr,
1223                         unsigned long old_len, unsigned long new_len,
1224                         unsigned long flags, unsigned long new_addr)
1225 {
1226         struct vm_area_struct *vma;
1227
1228         /* insanity checks first */
1229         if (new_len == 0)
1230                 return (unsigned long) -EINVAL;
1231
1232         if (flags & MREMAP_FIXED && new_addr != addr)
1233                 return (unsigned long) -EINVAL;
1234
1235         vma = find_vma_exact(current->mm, addr);
1236         if (!vma)
1237                 return (unsigned long) -EINVAL;
1238
1239         if (vma->vm_end != vma->vm_start + old_len)
1240                 return (unsigned long) -EFAULT;
1241
1242         if (vma->vm_flags & VM_MAYSHARE)
1243                 return (unsigned long) -EPERM;
1244
1245         if (new_len > kobjsize((void *) addr))
1246                 return (unsigned long) -ENOMEM;
1247
1248         /* all checks complete - do it */
1249         vma->vm_end = vma->vm_start + new_len;
1250
1251         askedalloc -= old_len;
1252         askedalloc += new_len;
1253
1254         return vma->vm_start;
1255 }
1256 EXPORT_SYMBOL(do_mremap);
1257
1258 asmlinkage unsigned long sys_mremap(unsigned long addr,
1259         unsigned long old_len, unsigned long new_len,
1260         unsigned long flags, unsigned long new_addr)
1261 {
1262         unsigned long ret;
1263
1264         down_write(&current->mm->mmap_sem);
1265         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1266         up_write(&current->mm->mmap_sem);
1267         return ret;
1268 }
1269
1270 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1271                         unsigned int foll_flags)
1272 {
1273         return NULL;
1274 }
1275
1276 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1277                 unsigned long to, unsigned long size, pgprot_t prot)
1278 {
1279         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1280         return 0;
1281 }
1282 EXPORT_SYMBOL(remap_pfn_range);
1283
1284 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1285                         unsigned long pgoff)
1286 {
1287         unsigned int size = vma->vm_end - vma->vm_start;
1288
1289         if (!(vma->vm_flags & VM_USERMAP))
1290                 return -EINVAL;
1291
1292         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1293         vma->vm_end = vma->vm_start + size;
1294
1295         return 0;
1296 }
1297 EXPORT_SYMBOL(remap_vmalloc_range);
1298
1299 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1300 {
1301 }
1302
1303 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1304         unsigned long len, unsigned long pgoff, unsigned long flags)
1305 {
1306         return -ENOMEM;
1307 }
1308
1309 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1310 {
1311 }
1312
1313 void unmap_mapping_range(struct address_space *mapping,
1314                          loff_t const holebegin, loff_t const holelen,
1315                          int even_cows)
1316 {
1317 }
1318 EXPORT_SYMBOL(unmap_mapping_range);
1319
1320 /*
1321  * ask for an unmapped area at which to create a mapping on a file
1322  */
1323 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1324                                 unsigned long len, unsigned long pgoff,
1325                                 unsigned long flags)
1326 {
1327         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1328                                   unsigned long, unsigned long);
1329
1330         get_area = current->mm->get_unmapped_area;
1331         if (file && file->f_op && file->f_op->get_unmapped_area)
1332                 get_area = file->f_op->get_unmapped_area;
1333
1334         if (!get_area)
1335                 return -ENOSYS;
1336
1337         return get_area(file, addr, len, pgoff, flags);
1338 }
1339 EXPORT_SYMBOL(get_unmapped_area);
1340
1341 /*
1342  * Check that a process has enough memory to allocate a new virtual
1343  * mapping. 0 means there is enough memory for the allocation to
1344  * succeed and -ENOMEM implies there is not.
1345  *
1346  * We currently support three overcommit policies, which are set via the
1347  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1348  *
1349  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1350  * Additional code 2002 Jul 20 by Robert Love.
1351  *
1352  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1353  *
1354  * Note this is a helper function intended to be used by LSMs which
1355  * wish to use this logic.
1356  */
1357 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1358 {
1359         unsigned long free, allowed;
1360
1361         vm_acct_memory(pages);
1362
1363         /*
1364          * Sometimes we want to use more memory than we have
1365          */
1366         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1367                 return 0;
1368
1369         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1370                 unsigned long n;
1371
1372                 free = global_page_state(NR_FILE_PAGES);
1373                 free += nr_swap_pages;
1374
1375                 /*
1376                  * Any slabs which are created with the
1377                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1378                  * which are reclaimable, under pressure.  The dentry
1379                  * cache and most inode caches should fall into this
1380                  */
1381                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1382
1383                 /*
1384                  * Leave the last 3% for root
1385                  */
1386                 if (!cap_sys_admin)
1387                         free -= free / 32;
1388
1389                 if (free > pages)
1390                         return 0;
1391
1392                 /*
1393                  * nr_free_pages() is very expensive on large systems,
1394                  * only call if we're about to fail.
1395                  */
1396                 n = nr_free_pages();
1397
1398                 /*
1399                  * Leave reserved pages. The pages are not for anonymous pages.
1400                  */
1401                 if (n <= totalreserve_pages)
1402                         goto error;
1403                 else
1404                         n -= totalreserve_pages;
1405
1406                 /*
1407                  * Leave the last 3% for root
1408                  */
1409                 if (!cap_sys_admin)
1410                         n -= n / 32;
1411                 free += n;
1412
1413                 if (free > pages)
1414                         return 0;
1415
1416                 goto error;
1417         }
1418
1419         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1420         /*
1421          * Leave the last 3% for root
1422          */
1423         if (!cap_sys_admin)
1424                 allowed -= allowed / 32;
1425         allowed += total_swap_pages;
1426
1427         /* Don't let a single process grow too big:
1428            leave 3% of the size of this process for other processes */
1429         allowed -= current->mm->total_vm / 32;
1430
1431         /*
1432          * cast `allowed' as a signed long because vm_committed_space
1433          * sometimes has a negative value
1434          */
1435         if (atomic_long_read(&vm_committed_space) < (long)allowed)
1436                 return 0;
1437 error:
1438         vm_unacct_memory(pages);
1439
1440         return -ENOMEM;
1441 }
1442
1443 int in_gate_area_no_task(unsigned long addr)
1444 {
1445         return 0;
1446 }
1447
1448 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1449 {
1450         BUG();
1451         return 0;
1452 }
1453 EXPORT_SYMBOL(filemap_fault);
1454
1455 /*
1456  * Access another process' address space.
1457  * - source/target buffer must be kernel space
1458  */
1459 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1460 {
1461         struct vm_area_struct *vma;
1462         struct mm_struct *mm;
1463
1464         if (addr + len < addr)
1465                 return 0;
1466
1467         mm = get_task_mm(tsk);
1468         if (!mm)
1469                 return 0;
1470
1471         down_read(&mm->mmap_sem);
1472
1473         /* the access must start within one of the target process's mappings */
1474         vma = find_vma(mm, addr);
1475         if (vma) {
1476                 /* don't overrun this mapping */
1477                 if (addr + len >= vma->vm_end)
1478                         len = vma->vm_end - addr;
1479
1480                 /* only read or write mappings where it is permitted */
1481                 if (write && vma->vm_flags & VM_MAYWRITE)
1482                         len -= copy_to_user((void *) addr, buf, len);
1483                 else if (!write && vma->vm_flags & VM_MAYREAD)
1484                         len -= copy_from_user(buf, (void *) addr, len);
1485                 else
1486                         len = 0;
1487         } else {
1488                 len = 0;
1489         }
1490
1491         up_read(&mm->mmap_sem);
1492         mmput(mm);
1493         return len;
1494 }