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/tracehook.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/backing-dev.h>
  28 #include <linux/mount.h>
  29 #include <linux/personality.h>
  30 #include <linux/security.h>
  31 #include <linux/syscalls.h>
  32
  33 #include <asm/uaccess.h>
  34 #include <asm/tlb.h>
  35 #include <asm/tlbflush.h>
  36
  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 #ifndef PAGE_KERNEL_EXEC
 270 # define PAGE_KERNEL_EXEC PAGE_KERNEL
 271 #endif
 272
 273 /**
 274  *      vmalloc_exec  -  allocate virtually contiguous, executable memory
 275  *      @size:          allocation size
 276  *
 277  *      Kernel-internal function to allocate enough pages to cover @size
 278  *      the page level allocator and map them into contiguous and
 279  *      executable kernel virtual space.
 280  *
 281  *      For tight control over page level allocator and protection flags
 282  *      use __vmalloc() instead.
 283  */
 284
 285 void *vmalloc_exec(unsigned long size)
 286 {
 287         return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC);
 288 }
 289
 290 /**
 291  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 292  *      @size:          allocation size
 293  *
 294  *      Allocate enough 32bit PA addressable pages to cover @size from the
 295  *      page level allocator and map them into continguos kernel virtual space.
 296  */
 297 void *vmalloc_32(unsigned long size)
 298 {
 299         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 300 }
 301 EXPORT_SYMBOL(vmalloc_32);
 302
 303 /**
 304  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 305  *      @size:          allocation size
 306  *
 307  * The resulting memory area is 32bit addressable and zeroed so it can be
 308  * mapped to userspace without leaking data.
 309  *
 310  * VM_USERMAP is set on the corresponding VMA so that subsequent calls to
 311  * remap_vmalloc_range() are permissible.
 312  */
 313 void *vmalloc_32_user(unsigned long size)
 314 {
 315         /*
 316          * We'll have to sort out the ZONE_DMA bits for 64-bit,
 317          * but for now this can simply use vmalloc_user() directly.
 318          */
 319         return vmalloc_user(size);
 320 }
 321 EXPORT_SYMBOL(vmalloc_32_user);
 322
 323 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 324 {
 325         BUG();
 326         return NULL;
 327 }
 328 EXPORT_SYMBOL(vmap);
 329
 330 void vunmap(const void *addr)
 331 {
 332         BUG();
 333 }
 334 EXPORT_SYMBOL(vunmap);
 335
 336 /*
 337  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 338  * have one.
 339  */
 340 void  __attribute__((weak)) vmalloc_sync_all(void)
 341 {
 342 }
 343
 344 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 345                    struct page *page)
 346 {
 347         return -EINVAL;
 348 }
 349 EXPORT_SYMBOL(vm_insert_page);
 350
 351 /*
 352  *  sys_brk() for the most part doesn't need the global kernel
 353  *  lock, except when an application is doing something nasty
 354  *  like trying to un-brk an area that has already been mapped
 355  *  to a regular file.  in this case, the unmapping will need
 356  *  to invoke file system routines that need the global lock.
 357  */
 358 asmlinkage unsigned long sys_brk(unsigned long brk)
 359 {
 360         struct mm_struct *mm = current->mm;
 361
 362         if (brk < mm->start_brk || brk > mm->context.end_brk)
 363                 return mm->brk;
 364
 365         if (mm->brk == brk)
 366                 return mm->brk;
 367
 368         /*
 369          * Always allow shrinking brk
 370          */
 371         if (brk <= mm->brk) {
 372                 mm->brk = brk;
 373                 return brk;
 374         }
 375
 376         /*
 377          * Ok, looks good - let it rip.
 378          */
 379         return mm->brk = brk;
 380 }
 381
 382 #ifdef DEBUG
 383 static void show_process_blocks(void)
 384 {
 385         struct vm_list_struct *vml;
 386
 387         printk("Process blocks %d:", current->pid);
 388
 389         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
 390                 printk(" %p: %p", vml, vml->vma);
 391                 if (vml->vma)
 392                         printk(" (%d @%lx #%d)",
 393                                kobjsize((void *) vml->vma->vm_start),
 394                                vml->vma->vm_start,
 395                                atomic_read(&vml->vma->vm_usage));
 396                 printk(vml->next ? " ->" : ".\n");
 397         }
 398 }
 399 #endif /* DEBUG */
 400
 401 /*
 402  * add a VMA into a process's mm_struct in the appropriate place in the list
 403  * - should be called with mm->mmap_sem held writelocked
 404  */
 405 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
 406 {
 407         struct vm_list_struct **ppv;
 408
 409         for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
 410                 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
 411                         break;
 412
 413         vml->next = *ppv;
 414         *ppv = vml;
 415 }
 416
 417 /*
 418  * look up the first VMA in which addr resides, NULL if none
 419  * - should be called with mm->mmap_sem at least held readlocked
 420  */
 421 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 422 {
 423         struct vm_list_struct *loop, *vml;
 424
 425         /* search the vm_start ordered list */
 426         vml = NULL;
 427         for (loop = mm->context.vmlist; loop; loop = loop->next) {
 428                 if (loop->vma->vm_start > addr)
 429                         break;
 430                 vml = loop;
 431         }
 432
 433         if (vml && vml->vma->vm_end > addr)
 434                 return vml->vma;
 435
 436         return NULL;
 437 }
 438 EXPORT_SYMBOL(find_vma);
 439
 440 /*
 441  * find a VMA
 442  * - we don't extend stack VMAs under NOMMU conditions
 443  */
 444 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 445 {
 446         return find_vma(mm, addr);
 447 }
 448
 449 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 450 {
 451         return -ENOMEM;
 452 }
 453
 454 /*
 455  * look up the first VMA exactly that exactly matches addr
 456  * - should be called with mm->mmap_sem at least held readlocked
 457  */
 458 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 459                                                     unsigned long addr)
 460 {
 461         struct vm_list_struct *vml;
 462
 463         /* search the vm_start ordered list */
 464         for (vml = mm->context.vmlist; vml; vml = vml->next) {
 465                 if (vml->vma->vm_start == addr)
 466                         return vml->vma;
 467                 if (vml->vma->vm_start > addr)
 468                         break;
 469         }
 470
 471         return NULL;
 472 }
 473
 474 /*
 475  * find a VMA in the global tree
 476  */
 477 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
 478 {
 479         struct vm_area_struct *vma;
 480         struct rb_node *n = nommu_vma_tree.rb_node;
 481
 482         while (n) {
 483                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 484
 485                 if (start < vma->vm_start)
 486                         n = n->rb_left;
 487                 else if (start > vma->vm_start)
 488                         n = n->rb_right;
 489                 else
 490                         return vma;
 491         }
 492
 493         return NULL;
 494 }
 495
 496 /*
 497  * add a VMA in the global tree
 498  */
 499 static void add_nommu_vma(struct vm_area_struct *vma)
 500 {
 501         struct vm_area_struct *pvma;
 502         struct address_space *mapping;
 503         struct rb_node **p = &nommu_vma_tree.rb_node;
 504         struct rb_node *parent = NULL;
 505
 506         /* add the VMA to the mapping */
 507         if (vma->vm_file) {
 508                 mapping = vma->vm_file->f_mapping;
 509
 510                 flush_dcache_mmap_lock(mapping);
 511                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 512                 flush_dcache_mmap_unlock(mapping);
 513         }
 514
 515         /* add the VMA to the master list */
 516         while (*p) {
 517                 parent = *p;
 518                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 519
 520                 if (vma->vm_start < pvma->vm_start) {
 521                         p = &(*p)->rb_left;
 522                 }
 523                 else if (vma->vm_start > pvma->vm_start) {
 524                         p = &(*p)->rb_right;
 525                 }
 526                 else {
 527                         /* mappings are at the same address - this can only
 528                          * happen for shared-mem chardevs and shared file
 529                          * mappings backed by ramfs/tmpfs */
 530                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
 531
 532                         if (vma < pvma)
 533                                 p = &(*p)->rb_left;
 534                         else if (vma > pvma)
 535                                 p = &(*p)->rb_right;
 536                         else
 537                                 BUG();
 538                 }
 539         }
 540
 541         rb_link_node(&vma->vm_rb, parent, p);
 542         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
 543 }
 544
 545 /*
 546  * delete a VMA from the global list
 547  */
 548 static void delete_nommu_vma(struct vm_area_struct *vma)
 549 {
 550         struct address_space *mapping;
 551
 552         /* remove the VMA from the mapping */
 553         if (vma->vm_file) {
 554                 mapping = vma->vm_file->f_mapping;
 555
 556                 flush_dcache_mmap_lock(mapping);
 557                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 558                 flush_dcache_mmap_unlock(mapping);
 559         }
 560
 561         /* remove from the master list */
 562         rb_erase(&vma->vm_rb, &nommu_vma_tree);
 563 }
 564
 565 /*
 566  * determine whether a mapping should be permitted and, if so, what sort of
 567  * mapping we're capable of supporting
 568  */
 569 static int validate_mmap_request(struct file *file,
 570                                  unsigned long addr,
 571                                  unsigned long len,
 572                                  unsigned long prot,
 573                                  unsigned long flags,
 574                                  unsigned long pgoff,
 575                                  unsigned long *_capabilities)
 576 {
 577         unsigned long capabilities;
 578         unsigned long reqprot = prot;
 579         int ret;
 580
 581         /* do the simple checks first */
 582         if (flags & MAP_FIXED || addr) {
 583                 printk(KERN_DEBUG
 584                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 585                        current->pid);
 586                 return -EINVAL;
 587         }
 588
 589         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 590             (flags & MAP_TYPE) != MAP_SHARED)
 591                 return -EINVAL;
 592
 593         if (!len)
 594                 return -EINVAL;
 595
 596         /* Careful about overflows.. */
 597         len = PAGE_ALIGN(len);
 598         if (!len || len > TASK_SIZE)
 599                 return -ENOMEM;
 600
 601         /* offset overflow? */
 602         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 603                 return -EOVERFLOW;
 604
 605         if (file) {
 606                 /* validate file mapping requests */
 607                 struct address_space *mapping;
 608
 609                 /* files must support mmap */
 610                 if (!file->f_op || !file->f_op->mmap)
 611                         return -ENODEV;
 612
 613                 /* work out if what we've got could possibly be shared
 614                  * - we support chardevs that provide their own "memory"
 615                  * - we support files/blockdevs that are memory backed
 616                  */
 617                 mapping = file->f_mapping;
 618                 if (!mapping)
 619                         mapping = file->f_path.dentry->d_inode->i_mapping;
 620
 621                 capabilities = 0;
 622                 if (mapping && mapping->backing_dev_info)
 623                         capabilities = mapping->backing_dev_info->capabilities;
 624
 625                 if (!capabilities) {
 626                         /* no explicit capabilities set, so assume some
 627                          * defaults */
 628                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
 629                         case S_IFREG:
 630                         case S_IFBLK:
 631                                 capabilities = BDI_CAP_MAP_COPY;
 632                                 break;
 633
 634                         case S_IFCHR:
 635                                 capabilities =
 636                                         BDI_CAP_MAP_DIRECT |
 637                                         BDI_CAP_READ_MAP |
 638                                         BDI_CAP_WRITE_MAP;
 639                                 break;
 640
 641                         default:
 642                                 return -EINVAL;
 643                         }
 644                 }
 645
 646                 /* eliminate any capabilities that we can't support on this
 647                  * device */
 648                 if (!file->f_op->get_unmapped_area)
 649                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 650                 if (!file->f_op->read)
 651                         capabilities &= ~BDI_CAP_MAP_COPY;
 652
 653                 if (flags & MAP_SHARED) {
 654                         /* do checks for writing, appending and locking */
 655                         if ((prot & PROT_WRITE) &&
 656                             !(file->f_mode & FMODE_WRITE))
 657                                 return -EACCES;
 658
 659                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
 660                             (file->f_mode & FMODE_WRITE))
 661                                 return -EACCES;
 662
 663                         if (locks_verify_locked(file->f_path.dentry->d_inode))
 664                                 return -EAGAIN;
 665
 666                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 667                                 return -ENODEV;
 668
 669                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
 670                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
 671                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
 672                             ) {
 673                                 printk("MAP_SHARED not completely supported on !MMU\n");
 674                                 return -EINVAL;
 675                         }
 676
 677                         /* we mustn't privatise shared mappings */
 678                         capabilities &= ~BDI_CAP_MAP_COPY;
 679                 }
 680                 else {
 681                         /* we're going to read the file into private memory we
 682                          * allocate */
 683                         if (!(capabilities & BDI_CAP_MAP_COPY))
 684                                 return -ENODEV;
 685
 686                         /* we don't permit a private writable mapping to be
 687                          * shared with the backing device */
 688                         if (prot & PROT_WRITE)
 689                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 690                 }
 691
 692                 /* handle executable mappings and implied executable
 693                  * mappings */
 694                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
 695                         if (prot & PROT_EXEC)
 696                                 return -EPERM;
 697                 }
 698                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 699                         /* handle implication of PROT_EXEC by PROT_READ */
 700                         if (current->personality & READ_IMPLIES_EXEC) {
 701                                 if (capabilities & BDI_CAP_EXEC_MAP)
 702                                         prot |= PROT_EXEC;
 703                         }
 704                 }
 705                 else if ((prot & PROT_READ) &&
 706                          (prot & PROT_EXEC) &&
 707                          !(capabilities & BDI_CAP_EXEC_MAP)
 708                          ) {
 709                         /* backing file is not executable, try to copy */
 710                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 711                 }
 712         }
 713         else {
 714                 /* anonymous mappings are always memory backed and can be
 715                  * privately mapped
 716                  */
 717                 capabilities = BDI_CAP_MAP_COPY;
 718
 719                 /* handle PROT_EXEC implication by PROT_READ */
 720                 if ((prot & PROT_READ) &&
 721                     (current->personality & READ_IMPLIES_EXEC))
 722                         prot |= PROT_EXEC;
 723         }
 724
 725         /* allow the security API to have its say */
 726         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
 727         if (ret < 0)
 728                 return ret;
 729
 730         /* looks okay */
 731         *_capabilities = capabilities;
 732         return 0;
 733 }
 734
 735 /*
 736  * we've determined that we can make the mapping, now translate what we
 737  * now know into VMA flags
 738  */
 739 static unsigned long determine_vm_flags(struct file *file,
 740                                         unsigned long prot,
 741                                         unsigned long flags,
 742                                         unsigned long capabilities)
 743 {
 744         unsigned long vm_flags;
 745
 746         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
 747         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 748         /* vm_flags |= mm->def_flags; */
 749
 750         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
 751                 /* attempt to share read-only copies of mapped file chunks */
 752                 if (file && !(prot & PROT_WRITE))
 753                         vm_flags |= VM_MAYSHARE;
 754         }
 755         else {
 756                 /* overlay a shareable mapping on the backing device or inode
 757                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 758                  * romfs/cramfs */
 759                 if (flags & MAP_SHARED)
 760                         vm_flags |= VM_MAYSHARE | VM_SHARED;
 761                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
 762                         vm_flags |= VM_MAYSHARE;
 763         }
 764
 765         /* refuse to let anyone share private mappings with this process if
 766          * it's being traced - otherwise breakpoints set in it may interfere
 767          * with another untraced process
 768          */
 769         if ((flags & MAP_PRIVATE) && tracehook_expect_breakpoints(current))
 770                 vm_flags &= ~VM_MAYSHARE;
 771
 772         return vm_flags;
 773 }
 774
 775 /*
 776  * set up a shared mapping on a file
 777  */
 778 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
 779 {
 780         int ret;
 781
 782         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 783         if (ret != -ENOSYS)
 784                 return ret;
 785
 786         /* getting an ENOSYS error indicates that direct mmap isn't
 787          * possible (as opposed to tried but failed) so we'll fall
 788          * through to making a private copy of the data and mapping
 789          * that if we can */
 790         return -ENODEV;
 791 }
 792
 793 /*
 794  * set up a private mapping or an anonymous shared mapping
 795  */
 796 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
 797 {
 798         void *base;
 799         int ret;
 800
 801         /* invoke the file's mapping function so that it can keep track of
 802          * shared mappings on devices or memory
 803          * - VM_MAYSHARE will be set if it may attempt to share
 804          */
 805         if (vma->vm_file) {
 806                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 807                 if (ret != -ENOSYS) {
 808                         /* shouldn't return success if we're not sharing */
 809                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
 810                         return ret; /* success or a real error */
 811                 }
 812
 813                 /* getting an ENOSYS error indicates that direct mmap isn't
 814                  * possible (as opposed to tried but failed) so we'll try to
 815                  * make a private copy of the data and map that instead */
 816         }
 817
 818         /* allocate some memory to hold the mapping
 819          * - note that this may not return a page-aligned address if the object
 820          *   we're allocating is smaller than a page
 821          */
 822         base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
 823         if (!base)
 824                 goto enomem;
 825
 826         vma->vm_start = (unsigned long) base;
 827         vma->vm_end = vma->vm_start + len;
 828         vma->vm_flags |= VM_MAPPED_COPY;
 829
 830 #ifdef WARN_ON_SLACK
 831         if (len + WARN_ON_SLACK <= kobjsize(result))
 832                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
 833                        len, current->pid, kobjsize(result) - len);
 834 #endif
 835
 836         if (vma->vm_file) {
 837                 /* read the contents of a file into the copy */
 838                 mm_segment_t old_fs;
 839                 loff_t fpos;
 840
 841                 fpos = vma->vm_pgoff;
 842                 fpos <<= PAGE_SHIFT;
 843
 844                 old_fs = get_fs();
 845                 set_fs(KERNEL_DS);
 846                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
 847                 set_fs(old_fs);
 848
 849                 if (ret < 0)
 850                         goto error_free;
 851
 852                 /* clear the last little bit */
 853                 if (ret < len)
 854                         memset(base + ret, 0, len - ret);
 855
 856         } else {
 857                 /* if it's an anonymous mapping, then just clear it */
 858                 memset(base, 0, len);
 859         }
 860
 861         return 0;
 862
 863 error_free:
 864         kfree(base);
 865         vma->vm_start = 0;
 866         return ret;
 867
 868 enomem:
 869         printk("Allocation of length %lu from process %d failed\n",
 870                len, current->pid);
 871         show_free_areas();
 872         return -ENOMEM;
 873 }
 874
 875 /*
 876  * handle mapping creation for uClinux
 877  */
 878 unsigned long do_mmap_pgoff(struct file *file,
 879                             unsigned long addr,
 880                             unsigned long len,
 881                             unsigned long prot,
 882                             unsigned long flags,
 883                             unsigned long pgoff)
 884 {
 885         struct vm_list_struct *vml = NULL;
 886         struct vm_area_struct *vma = NULL;
 887         struct rb_node *rb;
 888         unsigned long capabilities, vm_flags;
 889         void *result;
 890         int ret;
 891
 892         if (!(flags & MAP_FIXED))
 893                 addr = round_hint_to_min(addr);
 894
 895         /* decide whether we should attempt the mapping, and if so what sort of
 896          * mapping */
 897         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
 898                                     &capabilities);
 899         if (ret < 0)
 900                 return ret;
 901
 902         /* we've determined that we can make the mapping, now translate what we
 903          * now know into VMA flags */
 904         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
 905
 906         /* we're going to need to record the mapping if it works */
 907         vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
 908         if (!vml)
 909                 goto error_getting_vml;
 910
 911         down_write(&nommu_vma_sem);
 912
 913         /* if we want to share, we need to check for VMAs created by other
 914          * mmap() calls that overlap with our proposed mapping
 915          * - we can only share with an exact match on most regular files
 916          * - shared mappings on character devices and memory backed files are
 917          *   permitted to overlap inexactly as far as we are concerned for in
 918          *   these cases, sharing is handled in the driver or filesystem rather
 919          *   than here
 920          */
 921         if (vm_flags & VM_MAYSHARE) {
 922                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 923                 unsigned long vmpglen;
 924
 925                 /* suppress VMA sharing for shared regions */
 926                 if (vm_flags & VM_SHARED &&
 927                     capabilities & BDI_CAP_MAP_DIRECT)
 928                         goto dont_share_VMAs;
 929
 930                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
 931                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
 932
 933                         if (!(vma->vm_flags & VM_MAYSHARE))
 934                                 continue;
 935
 936                         /* search for overlapping mappings on the same file */
 937                         if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
 938                                 continue;
 939
 940                         if (vma->vm_pgoff >= pgoff + pglen)
 941                                 continue;
 942
 943                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
 944                         vmpglen >>= PAGE_SHIFT;
 945                         if (pgoff >= vma->vm_pgoff + vmpglen)
 946                                 continue;
 947
 948                         /* handle inexactly overlapping matches between mappings */
 949                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
 950                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
 951                                         goto sharing_violation;
 952                                 continue;
 953                         }
 954
 955                         /* we've found a VMA we can share */
 956                         atomic_inc(&vma->vm_usage);
 957
 958                         vml->vma = vma;
 959                         result = (void *) vma->vm_start;
 960                         goto shared;
 961                 }
 962
 963         dont_share_VMAs:
 964                 vma = NULL;
 965
 966                 /* obtain the address at which to make a shared mapping
 967                  * - this is the hook for quasi-memory character devices to
 968                  *   tell us the location of a shared mapping
 969                  */
 970                 if (file && file->f_op->get_unmapped_area) {
 971                         addr = file->f_op->get_unmapped_area(file, addr, len,
 972                                                              pgoff, flags);
 973                         if (IS_ERR((void *) addr)) {
 974                                 ret = addr;
 975                                 if (ret != (unsigned long) -ENOSYS)
 976                                         goto error;
 977
 978                                 /* the driver refused to tell us where to site
 979                                  * the mapping so we'll have to attempt to copy
 980                                  * it */
 981                                 ret = (unsigned long) -ENODEV;
 982                                 if (!(capabilities & BDI_CAP_MAP_COPY))
 983                                         goto error;
 984
 985                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 986                         }
 987                 }
 988         }
 989
 990         /* we're going to need a VMA struct as well */
 991         vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
 992         if (!vma)
 993                 goto error_getting_vma;
 994
 995         INIT_LIST_HEAD(&vma->anon_vma_node);
 996         atomic_set(&vma->vm_usage, 1);
 997         if (file) {
 998                 get_file(file);
 999                 if (vm_flags & VM_EXECUTABLE) {
1000                         added_exe_file_vma(current->mm);
1001                         vma->vm_mm = current->mm;
1002                 }
1003         }
1004         vma->vm_file    = file;
1005         vma->vm_flags   = vm_flags;
1006         vma->vm_start   = addr;
1007         vma->vm_end     = addr + len;
1008         vma->vm_pgoff   = pgoff;
1009
1010         vml->vma = vma;
1011
1012         /* set up the mapping */
1013         if (file && vma->vm_flags & VM_SHARED)
1014                 ret = do_mmap_shared_file(vma, len);
1015         else
1016                 ret = do_mmap_private(vma, len);
1017         if (ret < 0)
1018                 goto error;
1019
1020         /* okay... we have a mapping; now we have to register it */
1021         result = (void *) vma->vm_start;
1022
1023         if (vma->vm_flags & VM_MAPPED_COPY) {
1024                 realalloc += kobjsize(result);
1025                 askedalloc += len;
1026         }
1027
1028         realalloc += kobjsize(vma);
1029         askedalloc += sizeof(*vma);
1030
1031         current->mm->total_vm += len >> PAGE_SHIFT;
1032
1033         add_nommu_vma(vma);
1034
1035  shared:
1036         realalloc += kobjsize(vml);
1037         askedalloc += sizeof(*vml);
1038
1039         add_vma_to_mm(current->mm, vml);
1040
1041         up_write(&nommu_vma_sem);
1042
1043         if (prot & PROT_EXEC)
1044                 flush_icache_range((unsigned long) result,
1045                                    (unsigned long) result + len);
1046
1047 #ifdef DEBUG
1048         printk("do_mmap:\n");
1049         show_process_blocks();
1050 #endif
1051
1052         return (unsigned long) result;
1053
1054  error:
1055         up_write(&nommu_vma_sem);
1056         kfree(vml);
1057         if (vma) {
1058                 if (vma->vm_file) {
1059                         fput(vma->vm_file);
1060                         if (vma->vm_flags & VM_EXECUTABLE)
1061                                 removed_exe_file_vma(vma->vm_mm);
1062                 }
1063                 kfree(vma);
1064         }
1065         return ret;
1066
1067  sharing_violation:
1068         up_write(&nommu_vma_sem);
1069         printk("Attempt to share mismatched mappings\n");
1070         kfree(vml);
1071         return -EINVAL;
1072
1073  error_getting_vma:
1074         up_write(&nommu_vma_sem);
1075         kfree(vml);
1076         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
1077                len, current->pid);
1078         show_free_areas();
1079         return -ENOMEM;
1080
1081  error_getting_vml:
1082         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
1083                len, current->pid);
1084         show_free_areas();
1085         return -ENOMEM;
1086 }
1087 EXPORT_SYMBOL(do_mmap_pgoff);
1088
1089 /*
1090  * handle mapping disposal for uClinux
1091  */
1092 static void put_vma(struct mm_struct *mm, struct vm_area_struct *vma)
1093 {
1094         if (vma) {
1095                 down_write(&nommu_vma_sem);
1096
1097                 if (atomic_dec_and_test(&vma->vm_usage)) {
1098                         delete_nommu_vma(vma);
1099
1100                         if (vma->vm_ops && vma->vm_ops->close)
1101                                 vma->vm_ops->close(vma);
1102
1103                         /* IO memory and memory shared directly out of the pagecache from
1104                          * ramfs/tmpfs mustn't be released here */
1105                         if (vma->vm_flags & VM_MAPPED_COPY) {
1106                                 realalloc -= kobjsize((void *) vma->vm_start);
1107                                 askedalloc -= vma->vm_end - vma->vm_start;
1108                                 kfree((void *) vma->vm_start);
1109                         }
1110
1111                         realalloc -= kobjsize(vma);
1112                         askedalloc -= sizeof(*vma);
1113
1114                         if (vma->vm_file) {
1115                                 fput(vma->vm_file);
1116                                 if (vma->vm_flags & VM_EXECUTABLE)
1117                                         removed_exe_file_vma(mm);
1118                         }
1119                         kfree(vma);
1120                 }
1121
1122                 up_write(&nommu_vma_sem);
1123         }
1124 }
1125
1126 /*
1127  * release a mapping
1128  * - under NOMMU conditions the parameters must match exactly to the mapping to
1129  *   be removed
1130  */
1131 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1132 {
1133         struct vm_list_struct *vml, **parent;
1134         unsigned long end = addr + len;
1135
1136 #ifdef DEBUG
1137         printk("do_munmap:\n");
1138 #endif
1139
1140         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1141                 if ((*parent)->vma->vm_start > addr)
1142                         break;
1143                 if ((*parent)->vma->vm_start == addr &&
1144                     ((len == 0) || ((*parent)->vma->vm_end == end)))
1145                         goto found;
1146         }
1147
1148         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1149                current->pid, current->comm, (void *) addr);
1150         return -EINVAL;
1151
1152  found:
1153         vml = *parent;
1154
1155         put_vma(mm, vml->vma);
1156
1157         *parent = vml->next;
1158         realalloc -= kobjsize(vml);
1159         askedalloc -= sizeof(*vml);
1160         kfree(vml);
1161
1162         update_hiwater_vm(mm);
1163         mm->total_vm -= len >> PAGE_SHIFT;
1164
1165 #ifdef DEBUG
1166         show_process_blocks();
1167 #endif
1168
1169         return 0;
1170 }
1171 EXPORT_SYMBOL(do_munmap);
1172
1173 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1174 {
1175         int ret;
1176         struct mm_struct *mm = current->mm;
1177
1178         down_write(&mm->mmap_sem);
1179         ret = do_munmap(mm, addr, len);
1180         up_write(&mm->mmap_sem);
1181         return ret;
1182 }
1183
1184 /*
1185  * Release all mappings
1186  */
1187 void exit_mmap(struct mm_struct * mm)
1188 {
1189         struct vm_list_struct *tmp;
1190
1191         if (mm) {
1192 #ifdef DEBUG
1193                 printk("Exit_mmap:\n");
1194 #endif
1195
1196                 mm->total_vm = 0;
1197
1198                 while ((tmp = mm->context.vmlist)) {
1199                         mm->context.vmlist = tmp->next;
1200                         put_vma(mm, tmp->vma);
1201
1202                         realalloc -= kobjsize(tmp);
1203                         askedalloc -= sizeof(*tmp);
1204                         kfree(tmp);
1205                 }
1206
1207 #ifdef DEBUG
1208                 show_process_blocks();
1209 #endif
1210         }
1211 }
1212
1213 unsigned long do_brk(unsigned long addr, unsigned long len)
1214 {
1215         return -ENOMEM;
1216 }
1217
1218 /*
1219  * expand (or shrink) an existing mapping, potentially moving it at the same
1220  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1221  *
1222  * under NOMMU conditions, we only permit changing a mapping's size, and only
1223  * as long as it stays within the hole allocated by the kmalloc() call in
1224  * do_mmap_pgoff() and the block is not shareable
1225  *
1226  * MREMAP_FIXED is not supported under NOMMU conditions
1227  */
1228 unsigned long do_mremap(unsigned long addr,
1229                         unsigned long old_len, unsigned long new_len,
1230                         unsigned long flags, unsigned long new_addr)
1231 {
1232         struct vm_area_struct *vma;
1233
1234         /* insanity checks first */
1235         if (new_len == 0)
1236                 return (unsigned long) -EINVAL;
1237
1238         if (flags & MREMAP_FIXED && new_addr != addr)
1239                 return (unsigned long) -EINVAL;
1240
1241         vma = find_vma_exact(current->mm, addr);
1242         if (!vma)
1243                 return (unsigned long) -EINVAL;
1244
1245         if (vma->vm_end != vma->vm_start + old_len)
1246                 return (unsigned long) -EFAULT;
1247
1248         if (vma->vm_flags & VM_MAYSHARE)
1249                 return (unsigned long) -EPERM;
1250
1251         if (new_len > kobjsize((void *) addr))
1252                 return (unsigned long) -ENOMEM;
1253
1254         /* all checks complete - do it */
1255         vma->vm_end = vma->vm_start + new_len;
1256
1257         askedalloc -= old_len;
1258         askedalloc += new_len;
1259
1260         return vma->vm_start;
1261 }
1262 EXPORT_SYMBOL(do_mremap);
1263
1264 asmlinkage unsigned long sys_mremap(unsigned long addr,
1265         unsigned long old_len, unsigned long new_len,
1266         unsigned long flags, unsigned long new_addr)
1267 {
1268         unsigned long ret;
1269
1270         down_write(&current->mm->mmap_sem);
1271         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1272         up_write(&current->mm->mmap_sem);
1273         return ret;
1274 }
1275
1276 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1277                         unsigned int foll_flags)
1278 {
1279         return NULL;
1280 }
1281
1282 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1283                 unsigned long to, unsigned long size, pgprot_t prot)
1284 {
1285         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1286         return 0;
1287 }
1288 EXPORT_SYMBOL(remap_pfn_range);
1289
1290 int remap_vmalloc_range(struct vm_area_struct *vma, void *addr,
1291                         unsigned long pgoff)
1292 {
1293         unsigned int size = vma->vm_end - vma->vm_start;
1294
1295         if (!(vma->vm_flags & VM_USERMAP))
1296                 return -EINVAL;
1297
1298         vma->vm_start = (unsigned long)(addr + (pgoff << PAGE_SHIFT));
1299         vma->vm_end = vma->vm_start + size;
1300
1301         return 0;
1302 }
1303 EXPORT_SYMBOL(remap_vmalloc_range);
1304
1305 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1306 {
1307 }
1308
1309 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1310         unsigned long len, unsigned long pgoff, unsigned long flags)
1311 {
1312         return -ENOMEM;
1313 }
1314
1315 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1316 {
1317 }
1318
1319 void unmap_mapping_range(struct address_space *mapping,
1320                          loff_t const holebegin, loff_t const holelen,
1321                          int even_cows)
1322 {
1323 }
1324 EXPORT_SYMBOL(unmap_mapping_range);
1325
1326 /*
1327  * ask for an unmapped area at which to create a mapping on a file
1328  */
1329 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1330                                 unsigned long len, unsigned long pgoff,
1331                                 unsigned long flags)
1332 {
1333         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1334                                   unsigned long, unsigned long);
1335
1336         get_area = current->mm->get_unmapped_area;
1337         if (file && file->f_op && file->f_op->get_unmapped_area)
1338                 get_area = file->f_op->get_unmapped_area;
1339
1340         if (!get_area)
1341                 return -ENOSYS;
1342
1343         return get_area(file, addr, len, pgoff, flags);
1344 }
1345 EXPORT_SYMBOL(get_unmapped_area);
1346
1347 /*
1348  * Check that a process has enough memory to allocate a new virtual
1349  * mapping. 0 means there is enough memory for the allocation to
1350  * succeed and -ENOMEM implies there is not.
1351  *
1352  * We currently support three overcommit policies, which are set via the
1353  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1354  *
1355  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1356  * Additional code 2002 Jul 20 by Robert Love.
1357  *
1358  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1359  *
1360  * Note this is a helper function intended to be used by LSMs which
1361  * wish to use this logic.
1362  */
1363 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1364 {
1365         unsigned long free, allowed;
1366
1367         vm_acct_memory(pages);
1368
1369         /*
1370          * Sometimes we want to use more memory than we have
1371          */
1372         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1373                 return 0;
1374
1375         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1376                 unsigned long n;
1377
1378                 free = global_page_state(NR_FILE_PAGES);
1379                 free += nr_swap_pages;
1380
1381                 /*
1382                  * Any slabs which are created with the
1383                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1384                  * which are reclaimable, under pressure.  The dentry
1385                  * cache and most inode caches should fall into this
1386                  */
1387                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1388
1389                 /*
1390                  * Leave the last 3% for root
1391                  */
1392                 if (!cap_sys_admin)
1393                         free -= free / 32;
1394
1395                 if (free > pages)
1396                         return 0;
1397
1398                 /*
1399                  * nr_free_pages() is very expensive on large systems,
1400                  * only call if we're about to fail.
1401                  */
1402                 n = nr_free_pages();
1403
1404                 /*
1405                  * Leave reserved pages. The pages are not for anonymous pages.
1406                  */
1407                 if (n <= totalreserve_pages)
1408                         goto error;
1409                 else
1410                         n -= totalreserve_pages;
1411
1412                 /*
1413                  * Leave the last 3% for root
1414                  */
1415                 if (!cap_sys_admin)
1416                         n -= n / 32;
1417                 free += n;
1418
1419                 if (free > pages)
1420                         return 0;
1421
1422                 goto error;
1423         }
1424
1425         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1426         /*
1427          * Leave the last 3% for root
1428          */
1429         if (!cap_sys_admin)
1430                 allowed -= allowed / 32;
1431         allowed += total_swap_pages;
1432
1433         /* Don't let a single process grow too big:
1434            leave 3% of the size of this process for other processes */
1435         allowed -= current->mm->total_vm / 32;
1436
1437         /*
1438          * cast `allowed' as a signed long because vm_committed_space
1439          * sometimes has a negative value
1440          */
1441         if (atomic_long_read(&vm_committed_space) < (long)allowed)
1442                 return 0;
1443 error:
1444         vm_unacct_memory(pages);
1445
1446         return -ENOMEM;
1447 }
1448
1449 int in_gate_area_no_task(unsigned long addr)
1450 {
1451         return 0;
1452 }
1453
1454 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1455 {
1456         BUG();
1457         return 0;
1458 }
1459 EXPORT_SYMBOL(filemap_fault);
1460
1461 /*
1462  * Access another process' address space.
1463  * - source/target buffer must be kernel space
1464  */
1465 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1466 {
1467         struct vm_area_struct *vma;
1468         struct mm_struct *mm;
1469
1470         if (addr + len < addr)
1471                 return 0;
1472
1473         mm = get_task_mm(tsk);
1474         if (!mm)
1475                 return 0;
1476
1477         down_read(&mm->mmap_sem);
1478
1479         /* the access must start within one of the target process's mappings */
1480         vma = find_vma(mm, addr);
1481         if (vma) {
1482                 /* don't overrun this mapping */
1483                 if (addr + len >= vma->vm_end)
1484                         len = vma->vm_end - addr;
1485
1486                 /* only read or write mappings where it is permitted */
1487                 if (write && vma->vm_flags & VM_MAYWRITE)
1488                         len -= copy_to_user((void *) addr, buf, len);
1489                 else if (!write && vma->vm_flags & VM_MAYREAD)
1490                         len -= copy_from_user(buf, (void *) addr, len);
1491                 else
1492                         len = 0;
1493         } else {
1494                 len = 0;
1495         }
1496
1497         up_read(&mm->mmap_sem);
1498         mmput(mm);
1499         return len;
1500 }