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