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