err.no Git - linux-2.6/blob - 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  */
  14
  15 #include <linux/mm.h>
  16 #include <linux/mman.h>
  17 #include <linux/swap.h>
  18 #include <linux/file.h>
  19 #include <linux/highmem.h>
  20 #include <linux/pagemap.h>
  21 #include <linux/slab.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/ptrace.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/backing-dev.h>
  26 #include <linux/mount.h>
  27 #include <linux/personality.h>
  28 #include <linux/security.h>
  29 #include <linux/syscalls.h>
  30
  31 #include <asm/uaccess.h>
  32 #include <asm/tlb.h>
  33 #include <asm/tlbflush.h>
  34
  35 void *high_memory;
  36 struct page *mem_map;
  37 unsigned long max_mapnr;
  38 unsigned long num_physpages;
  39 unsigned long askedalloc, realalloc;
  40 atomic_t vm_committed_space = ATOMIC_INIT(0);
  41 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  42 int sysctl_overcommit_ratio = 50; /* default is 50% */
  43 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  44 int heap_stack_gap = 0;
  45
  46 EXPORT_SYMBOL(mem_map);
  47 EXPORT_SYMBOL(__vm_enough_memory);
  48
  49 /* list of shareable VMAs */
  50 struct rb_root nommu_vma_tree = RB_ROOT;
  51 DECLARE_RWSEM(nommu_vma_sem);
  52
  53 struct vm_operations_struct generic_file_vm_ops = {
  54 };
  55
  56 EXPORT_SYMBOL(vfree);
  57 EXPORT_SYMBOL(vmalloc_to_page);
  58 EXPORT_SYMBOL(vmalloc_32);
  59 EXPORT_SYMBOL(vmap);
  60 EXPORT_SYMBOL(vunmap);
  61
  62 /*
  63  * Handle all mappings that got truncated by a "truncate()"
  64  * system call.
  65  *
  66  * NOTE! We have to be ready to update the memory sharing
  67  * between the file and the memory map for a potential last
  68  * incomplete page.  Ugly, but necessary.
  69  */
  70 int vmtruncate(struct inode *inode, loff_t offset)
  71 {
  72         struct address_space *mapping = inode->i_mapping;
  73         unsigned long limit;
  74
  75         if (inode->i_size < offset)
  76                 goto do_expand;
  77         i_size_write(inode, offset);
  78
  79         truncate_inode_pages(mapping, offset);
  80         goto out_truncate;
  81
  82 do_expand:
  83         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
  84         if (limit != RLIM_INFINITY && offset > limit)
  85                 goto out_sig;
  86         if (offset > inode->i_sb->s_maxbytes)
  87                 goto out;
  88         i_size_write(inode, offset);
  89
  90 out_truncate:
  91         if (inode->i_op && inode->i_op->truncate)
  92                 inode->i_op->truncate(inode);
  93         return 0;
  94 out_sig:
  95         send_sig(SIGXFSZ, current, 0);
  96 out:
  97         return -EFBIG;
  98 }
  99
 100 EXPORT_SYMBOL(vmtruncate);
 101
 102 /*
 103  * Return the total memory allocated for this pointer, not
 104  * just what the caller asked for.
 105  *
 106  * Doesn't have to be accurate, i.e. may have races.
 107  */
 108 unsigned int kobjsize(const void *objp)
 109 {
 110         struct page *page;
 111
 112         if (!objp || !((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
 171 EXPORT_SYMBOL(get_user_pages);
 172
 173 DEFINE_RWLOCK(vmlist_lock);
 174 struct vm_struct *vmlist;
 175
 176 void vfree(void *addr)
 177 {
 178         kfree(addr);
 179 }
 180
 181 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 182 {
 183         /*
 184          * kmalloc doesn't like __GFP_HIGHMEM for some reason
 185          */
 186         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 187 }
 188
 189 struct page * vmalloc_to_page(void *addr)
 190 {
 191         return virt_to_page(addr);
 192 }
 193
 194 unsigned long vmalloc_to_pfn(void *addr)
 195 {
 196         return page_to_pfn(virt_to_page(addr));
 197 }
 198
 199
 200 long vread(char *buf, char *addr, unsigned long count)
 201 {
 202         memcpy(buf, addr, count);
 203         return count;
 204 }
 205
 206 long vwrite(char *buf, char *addr, unsigned long count)
 207 {
 208         /* Don't allow overflow */
 209         if ((unsigned long) addr + count < count)
 210                 count = -(unsigned long) addr;
 211
 212         memcpy(addr, buf, count);
 213         return(count);
 214 }
 215
 216 /*
 217  *      vmalloc  -  allocate virtually continguos memory
 218  *
 219  *      @size:          allocation size
 220  *
 221  *      Allocate enough pages to cover @size from the page level
 222  *      allocator and map them into continguos kernel virtual space.
 223  *
 224  *      For tight cotrol over page level allocator and protection flags
 225  *      use __vmalloc() instead.
 226  */
 227 void *vmalloc(unsigned long size)
 228 {
 229        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 230 }
 231 EXPORT_SYMBOL(vmalloc);
 232
 233 void *vmalloc_node(unsigned long size, int node)
 234 {
 235         return vmalloc(size);
 236 }
 237 EXPORT_SYMBOL(vmalloc_node);
 238
 239 /*
 240  *      vmalloc_32  -  allocate virtually continguos memory (32bit addressable)
 241  *
 242  *      @size:          allocation size
 243  *
 244  *      Allocate enough 32bit PA addressable pages to cover @size from the
 245  *      page level allocator and map them into continguos kernel virtual space.
 246  */
 247 void *vmalloc_32(unsigned long size)
 248 {
 249         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 250 }
 251
 252 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 253 {
 254         BUG();
 255         return NULL;
 256 }
 257
 258 void vunmap(void *addr)
 259 {
 260         BUG();
 261 }
 262
 263 /*
 264  *  sys_brk() for the most part doesn't need the global kernel
 265  *  lock, except when an application is doing something nasty
 266  *  like trying to un-brk an area that has already been mapped
 267  *  to a regular file.  in this case, the unmapping will need
 268  *  to invoke file system routines that need the global lock.
 269  */
 270 asmlinkage unsigned long sys_brk(unsigned long brk)
 271 {
 272         struct mm_struct *mm = current->mm;
 273
 274         if (brk < mm->start_brk || brk > mm->context.end_brk)
 275                 return mm->brk;
 276
 277         if (mm->brk == brk)
 278                 return mm->brk;
 279
 280         /*
 281          * Always allow shrinking brk
 282          */
 283         if (brk <= mm->brk) {
 284                 mm->brk = brk;
 285                 return brk;
 286         }
 287
 288         /*
 289          * Ok, looks good - let it rip.
 290          */
 291         return mm->brk = brk;
 292 }
 293
 294 #ifdef DEBUG
 295 static void show_process_blocks(void)
 296 {
 297         struct vm_list_struct *vml;
 298
 299         printk("Process blocks %d:", current->pid);
 300
 301         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
 302                 printk(" %p: %p", vml, vml->vma);
 303                 if (vml->vma)
 304                         printk(" (%d @%lx #%d)",
 305                                kobjsize((void *) vml->vma->vm_start),
 306                                vml->vma->vm_start,
 307                                atomic_read(&vml->vma->vm_usage));
 308                 printk(vml->next ? " ->" : ".\n");
 309         }
 310 }
 311 #endif /* DEBUG */
 312
 313 /*
 314  * add a VMA into a process's mm_struct in the appropriate place in the list
 315  * - should be called with mm->mmap_sem held writelocked
 316  */
 317 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
 318 {
 319         struct vm_list_struct **ppv;
 320
 321         for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
 322                 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
 323                         break;
 324
 325         vml->next = *ppv;
 326         *ppv = vml;
 327 }
 328
 329 /*
 330  * look up the first VMA in which addr resides, NULL if none
 331  * - should be called with mm->mmap_sem at least held readlocked
 332  */
 333 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 334 {
 335         struct vm_list_struct *loop, *vml;
 336
 337         /* search the vm_start ordered list */
 338         vml = NULL;
 339         for (loop = mm->context.vmlist; loop; loop = loop->next) {
 340                 if (loop->vma->vm_start > addr)
 341                         break;
 342                 vml = loop;
 343         }
 344
 345         if (vml && vml->vma->vm_end > addr)
 346                 return vml->vma;
 347
 348         return NULL;
 349 }
 350 EXPORT_SYMBOL(find_vma);
 351
 352 /*
 353  * look up the first VMA exactly that exactly matches addr
 354  * - should be called with mm->mmap_sem at least held readlocked
 355  */
 356 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 357                                                     unsigned long addr)
 358 {
 359         struct vm_list_struct *vml;
 360
 361         /* search the vm_start ordered list */
 362         for (vml = mm->context.vmlist; vml; vml = vml->next) {
 363                 if (vml->vma->vm_start == addr)
 364                         return vml->vma;
 365                 if (vml->vma->vm_start > addr)
 366                         break;
 367         }
 368
 369         return NULL;
 370 }
 371
 372 /*
 373  * find a VMA in the global tree
 374  */
 375 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
 376 {
 377         struct vm_area_struct *vma;
 378         struct rb_node *n = nommu_vma_tree.rb_node;
 379
 380         while (n) {
 381                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 382
 383                 if (start < vma->vm_start)
 384                         n = n->rb_left;
 385                 else if (start > vma->vm_start)
 386                         n = n->rb_right;
 387                 else
 388                         return vma;
 389         }
 390
 391         return NULL;
 392 }
 393
 394 /*
 395  * add a VMA in the global tree
 396  */
 397 static void add_nommu_vma(struct vm_area_struct *vma)
 398 {
 399         struct vm_area_struct *pvma;
 400         struct address_space *mapping;
 401         struct rb_node **p = &nommu_vma_tree.rb_node;
 402         struct rb_node *parent = NULL;
 403
 404         /* add the VMA to the mapping */
 405         if (vma->vm_file) {
 406                 mapping = vma->vm_file->f_mapping;
 407
 408                 flush_dcache_mmap_lock(mapping);
 409                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 410                 flush_dcache_mmap_unlock(mapping);
 411         }
 412
 413         /* add the VMA to the master list */
 414         while (*p) {
 415                 parent = *p;
 416                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 417
 418                 if (vma->vm_start < pvma->vm_start) {
 419                         p = &(*p)->rb_left;
 420                 }
 421                 else if (vma->vm_start > pvma->vm_start) {
 422                         p = &(*p)->rb_right;
 423                 }
 424                 else {
 425                         /* mappings are at the same address - this can only
 426                          * happen for shared-mem chardevs and shared file
 427                          * mappings backed by ramfs/tmpfs */
 428                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
 429
 430                         if (vma < pvma)
 431                                 p = &(*p)->rb_left;
 432                         else if (vma > pvma)
 433                                 p = &(*p)->rb_right;
 434                         else
 435                                 BUG();
 436                 }
 437         }
 438
 439         rb_link_node(&vma->vm_rb, parent, p);
 440         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
 441 }
 442
 443 /*
 444  * delete a VMA from the global list
 445  */
 446 static void delete_nommu_vma(struct vm_area_struct *vma)
 447 {
 448         struct address_space *mapping;
 449
 450         /* remove the VMA from the mapping */
 451         if (vma->vm_file) {
 452                 mapping = vma->vm_file->f_mapping;
 453
 454                 flush_dcache_mmap_lock(mapping);
 455                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 456                 flush_dcache_mmap_unlock(mapping);
 457         }
 458
 459         /* remove from the master list */
 460         rb_erase(&vma->vm_rb, &nommu_vma_tree);
 461 }
 462
 463 /*
 464  * determine whether a mapping should be permitted and, if so, what sort of
 465  * mapping we're capable of supporting
 466  */
 467 static int validate_mmap_request(struct file *file,
 468                                  unsigned long addr,
 469                                  unsigned long len,
 470                                  unsigned long prot,
 471                                  unsigned long flags,
 472                                  unsigned long pgoff,
 473                                  unsigned long *_capabilities)
 474 {
 475         unsigned long capabilities;
 476         unsigned long reqprot = prot;
 477         int ret;
 478
 479         /* do the simple checks first */
 480         if (flags & MAP_FIXED || addr) {
 481                 printk(KERN_DEBUG
 482                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 483                        current->pid);
 484                 return -EINVAL;
 485         }
 486
 487         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 488             (flags & MAP_TYPE) != MAP_SHARED)
 489                 return -EINVAL;
 490
 491         if (PAGE_ALIGN(len) == 0)
 492                 return addr;
 493
 494         if (len > TASK_SIZE)
 495                 return -EINVAL;
 496
 497         /* offset overflow? */
 498         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 499                 return -EINVAL;
 500
 501         if (file) {
 502                 /* validate file mapping requests */
 503                 struct address_space *mapping;
 504
 505                 /* files must support mmap */
 506                 if (!file->f_op || !file->f_op->mmap)
 507                         return -ENODEV;
 508
 509                 /* work out if what we've got could possibly be shared
 510                  * - we support chardevs that provide their own "memory"
 511                  * - we support files/blockdevs that are memory backed
 512                  */
 513                 mapping = file->f_mapping;
 514                 if (!mapping)
 515                         mapping = file->f_dentry->d_inode->i_mapping;
 516
 517                 capabilities = 0;
 518                 if (mapping && mapping->backing_dev_info)
 519                         capabilities = mapping->backing_dev_info->capabilities;
 520
 521                 if (!capabilities) {
 522                         /* no explicit capabilities set, so assume some
 523                          * defaults */
 524                         switch (file->f_dentry->d_inode->i_mode & S_IFMT) {
 525                         case S_IFREG:
 526                         case S_IFBLK:
 527                                 capabilities = BDI_CAP_MAP_COPY;
 528                                 break;
 529
 530                         case S_IFCHR:
 531                                 capabilities =
 532                                         BDI_CAP_MAP_DIRECT |
 533                                         BDI_CAP_READ_MAP |
 534                                         BDI_CAP_WRITE_MAP;
 535                                 break;
 536
 537                         default:
 538                                 return -EINVAL;
 539                         }
 540                 }
 541
 542                 /* eliminate any capabilities that we can't support on this
 543                  * device */
 544                 if (!file->f_op->get_unmapped_area)
 545                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 546                 if (!file->f_op->read)
 547                         capabilities &= ~BDI_CAP_MAP_COPY;
 548
 549                 if (flags & MAP_SHARED) {
 550                         /* do checks for writing, appending and locking */
 551                         if ((prot & PROT_WRITE) &&
 552                             !(file->f_mode & FMODE_WRITE))
 553                                 return -EACCES;
 554
 555                         if (IS_APPEND(file->f_dentry->d_inode) &&
 556                             (file->f_mode & FMODE_WRITE))
 557                                 return -EACCES;
 558
 559                         if (locks_verify_locked(file->f_dentry->d_inode))
 560                                 return -EAGAIN;
 561
 562                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 563                                 return -ENODEV;
 564
 565                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
 566                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
 567                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
 568                             ) {
 569                                 printk("MAP_SHARED not completely supported on !MMU\n");
 570                                 return -EINVAL;
 571                         }
 572
 573                         /* we mustn't privatise shared mappings */
 574                         capabilities &= ~BDI_CAP_MAP_COPY;
 575                 }
 576                 else {
 577                         /* we're going to read the file into private memory we
 578                          * allocate */
 579                         if (!(capabilities & BDI_CAP_MAP_COPY))
 580                                 return -ENODEV;
 581
 582                         /* we don't permit a private writable mapping to be
 583                          * shared with the backing device */
 584                         if (prot & PROT_WRITE)
 585                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 586                 }
 587
 588                 /* handle executable mappings and implied executable
 589                  * mappings */
 590                 if (file->f_vfsmnt->mnt_flags & MNT_NOEXEC) {
 591                         if (prot & PROT_EXEC)
 592                                 return -EPERM;
 593                 }
 594                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 595                         /* handle implication of PROT_EXEC by PROT_READ */
 596                         if (current->personality & READ_IMPLIES_EXEC) {
 597                                 if (capabilities & BDI_CAP_EXEC_MAP)
 598                                         prot |= PROT_EXEC;
 599                         }
 600                 }
 601                 else if ((prot & PROT_READ) &&
 602                          (prot & PROT_EXEC) &&
 603                          !(capabilities & BDI_CAP_EXEC_MAP)
 604                          ) {
 605                         /* backing file is not executable, try to copy */
 606                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 607                 }
 608         }
 609         else {
 610                 /* anonymous mappings are always memory backed and can be
 611                  * privately mapped
 612                  */
 613                 capabilities = BDI_CAP_MAP_COPY;
 614
 615                 /* handle PROT_EXEC implication by PROT_READ */
 616                 if ((prot & PROT_READ) &&
 617                     (current->personality & READ_IMPLIES_EXEC))
 618                         prot |= PROT_EXEC;
 619         }
 620
 621         /* allow the security API to have its say */
 622         ret = security_file_mmap(file, reqprot, prot, flags);
 623         if (ret < 0)
 624                 return ret;
 625
 626         /* looks okay */
 627         *_capabilities = capabilities;
 628         return 0;
 629 }
 630
 631 /*
 632  * we've determined that we can make the mapping, now translate what we
 633  * now know into VMA flags
 634  */
 635 static unsigned long determine_vm_flags(struct file *file,
 636                                         unsigned long prot,
 637                                         unsigned long flags,
 638                                         unsigned long capabilities)
 639 {
 640         unsigned long vm_flags;
 641
 642         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
 643         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 644         /* vm_flags |= mm->def_flags; */
 645
 646         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
 647                 /* attempt to share read-only copies of mapped file chunks */
 648                 if (file && !(prot & PROT_WRITE))
 649                         vm_flags |= VM_MAYSHARE;
 650         }
 651         else {
 652                 /* overlay a shareable mapping on the backing device or inode
 653                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 654                  * romfs/cramfs */
 655                 if (flags & MAP_SHARED)
 656                         vm_flags |= VM_MAYSHARE | VM_SHARED;
 657                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
 658                         vm_flags |= VM_MAYSHARE;
 659         }
 660
 661         /* refuse to let anyone share private mappings with this process if
 662          * it's being traced - otherwise breakpoints set in it may interfere
 663          * with another untraced process
 664          */
 665         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
 666                 vm_flags &= ~VM_MAYSHARE;
 667
 668         return vm_flags;
 669 }
 670
 671 /*
 672  * set up a shared mapping on a file
 673  */
 674 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
 675 {
 676         int ret;
 677
 678         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 679         if (ret != -ENOSYS)
 680                 return ret;
 681
 682         /* getting an ENOSYS error indicates that direct mmap isn't
 683          * possible (as opposed to tried but failed) so we'll fall
 684          * through to making a private copy of the data and mapping
 685          * that if we can */
 686         return -ENODEV;
 687 }
 688
 689 /*
 690  * set up a private mapping or an anonymous shared mapping
 691  */
 692 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
 693 {
 694         void *base;
 695         int ret;
 696
 697         /* invoke the file's mapping function so that it can keep track of
 698          * shared mappings on devices or memory
 699          * - VM_MAYSHARE will be set if it may attempt to share
 700          */
 701         if (vma->vm_file) {
 702                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 703                 if (ret != -ENOSYS) {
 704                         /* shouldn't return success if we're not sharing */
 705                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
 706                         return ret; /* success or a real error */
 707                 }
 708
 709                 /* getting an ENOSYS error indicates that direct mmap isn't
 710                  * possible (as opposed to tried but failed) so we'll try to
 711                  * make a private copy of the data and map that instead */
 712         }
 713
 714         /* allocate some memory to hold the mapping
 715          * - note that this may not return a page-aligned address if the object
 716          *   we're allocating is smaller than a page
 717          */
 718         base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
 719         if (!base)
 720                 goto enomem;
 721
 722         vma->vm_start = (unsigned long) base;
 723         vma->vm_end = vma->vm_start + len;
 724         vma->vm_flags |= VM_MAPPED_COPY;
 725
 726 #ifdef WARN_ON_SLACK
 727         if (len + WARN_ON_SLACK <= kobjsize(result))
 728                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
 729                        len, current->pid, kobjsize(result) - len);
 730 #endif
 731
 732         if (vma->vm_file) {
 733                 /* read the contents of a file into the copy */
 734                 mm_segment_t old_fs;
 735                 loff_t fpos;
 736
 737                 fpos = vma->vm_pgoff;
 738                 fpos <<= PAGE_SHIFT;
 739
 740                 old_fs = get_fs();
 741                 set_fs(KERNEL_DS);
 742                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
 743                 set_fs(old_fs);
 744
 745                 if (ret < 0)
 746                         goto error_free;
 747
 748                 /* clear the last little bit */
 749                 if (ret < len)
 750                         memset(base + ret, 0, len - ret);
 751
 752         } else {
 753                 /* if it's an anonymous mapping, then just clear it */
 754                 memset(base, 0, len);
 755         }
 756
 757         return 0;
 758
 759 error_free:
 760         kfree(base);
 761         vma->vm_start = 0;
 762         return ret;
 763
 764 enomem:
 765         printk("Allocation of length %lu from process %d failed\n",
 766                len, current->pid);
 767         show_free_areas();
 768         return -ENOMEM;
 769 }
 770
 771 /*
 772  * handle mapping creation for uClinux
 773  */
 774 unsigned long do_mmap_pgoff(struct file *file,
 775                             unsigned long addr,
 776                             unsigned long len,
 777                             unsigned long prot,
 778                             unsigned long flags,
 779                             unsigned long pgoff)
 780 {
 781         struct vm_list_struct *vml = NULL;
 782         struct vm_area_struct *vma = NULL;
 783         struct rb_node *rb;
 784         unsigned long capabilities, vm_flags;
 785         void *result;
 786         int ret;
 787
 788         /* decide whether we should attempt the mapping, and if so what sort of
 789          * mapping */
 790         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
 791                                     &capabilities);
 792         if (ret < 0)
 793                 return ret;
 794
 795         /* we've determined that we can make the mapping, now translate what we
 796          * now know into VMA flags */
 797         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
 798
 799         /* we're going to need to record the mapping if it works */
 800         vml = kmalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
 801         if (!vml)
 802                 goto error_getting_vml;
 803         memset(vml, 0, sizeof(*vml));
 804
 805         down_write(&nommu_vma_sem);
 806
 807         /* if we want to share, we need to check for VMAs created by other
 808          * mmap() calls that overlap with our proposed mapping
 809          * - we can only share with an exact match on most regular files
 810          * - shared mappings on character devices and memory backed files are
 811          *   permitted to overlap inexactly as far as we are concerned for in
 812          *   these cases, sharing is handled in the driver or filesystem rather
 813          *   than here
 814          */
 815         if (vm_flags & VM_MAYSHARE) {
 816                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 817                 unsigned long vmpglen;
 818
 819                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
 820                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
 821
 822                         if (!(vma->vm_flags & VM_MAYSHARE))
 823                                 continue;
 824
 825                         /* search for overlapping mappings on the same file */
 826                         if (vma->vm_file->f_dentry->d_inode != file->f_dentry->d_inode)
 827                                 continue;
 828
 829                         if (vma->vm_pgoff >= pgoff + pglen)
 830                                 continue;
 831
 832                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
 833                         vmpglen >>= PAGE_SHIFT;
 834                         if (pgoff >= vma->vm_pgoff + vmpglen)
 835                                 continue;
 836
 837                         /* handle inexactly overlapping matches between mappings */
 838                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
 839                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
 840                                         goto sharing_violation;
 841                                 continue;
 842                         }
 843
 844                         /* we've found a VMA we can share */
 845                         atomic_inc(&vma->vm_usage);
 846
 847                         vml->vma = vma;
 848                         result = (void *) vma->vm_start;
 849                         goto shared;
 850                 }
 851
 852                 vma = NULL;
 853
 854                 /* obtain the address at which to make a shared mapping
 855                  * - this is the hook for quasi-memory character devices to
 856                  *   tell us the location of a shared mapping
 857                  */
 858                 if (file && file->f_op->get_unmapped_area) {
 859                         addr = file->f_op->get_unmapped_area(file, addr, len,
 860                                                              pgoff, flags);
 861                         if (IS_ERR((void *) addr)) {
 862                                 ret = addr;
 863                                 if (ret != (unsigned long) -ENOSYS)
 864                                         goto error;
 865
 866                                 /* the driver refused to tell us where to site
 867                                  * the mapping so we'll have to attempt to copy
 868                                  * it */
 869                                 ret = (unsigned long) -ENODEV;
 870                                 if (!(capabilities & BDI_CAP_MAP_COPY))
 871                                         goto error;
 872
 873                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 874                         }
 875                 }
 876         }
 877
 878         /* we're going to need a VMA struct as well */
 879         vma = kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
 880         if (!vma)
 881                 goto error_getting_vma;
 882
 883         memset(vma, 0, sizeof(*vma));
 884         INIT_LIST_HEAD(&vma->anon_vma_node);
 885         atomic_set(&vma->vm_usage, 1);
 886         if (file)
 887                 get_file(file);
 888         vma->vm_file    = file;
 889         vma->vm_flags   = vm_flags;
 890         vma->vm_start   = addr;
 891         vma->vm_end     = addr + len;
 892         vma->vm_pgoff   = pgoff;
 893
 894         vml->vma = vma;
 895
 896         /* set up the mapping */
 897         if (file && vma->vm_flags & VM_SHARED)
 898                 ret = do_mmap_shared_file(vma, len);
 899         else
 900                 ret = do_mmap_private(vma, len);
 901         if (ret < 0)
 902                 goto error;
 903
 904         /* okay... we have a mapping; now we have to register it */
 905         result = (void *) vma->vm_start;
 906
 907         if (vma->vm_flags & VM_MAPPED_COPY) {
 908                 realalloc += kobjsize(result);
 909                 askedalloc += len;
 910         }
 911
 912         realalloc += kobjsize(vma);
 913         askedalloc += sizeof(*vma);
 914
 915         current->mm->total_vm += len >> PAGE_SHIFT;
 916
 917         add_nommu_vma(vma);
 918
 919  shared:
 920         realalloc += kobjsize(vml);
 921         askedalloc += sizeof(*vml);
 922
 923         add_vma_to_mm(current->mm, vml);
 924
 925         up_write(&nommu_vma_sem);
 926
 927         if (prot & PROT_EXEC)
 928                 flush_icache_range((unsigned long) result,
 929                                    (unsigned long) result + len);
 930
 931 #ifdef DEBUG
 932         printk("do_mmap:\n");
 933         show_process_blocks();
 934 #endif
 935
 936         return (unsigned long) result;
 937
 938  error:
 939         up_write(&nommu_vma_sem);
 940         kfree(vml);
 941         if (vma) {
 942                 fput(vma->vm_file);
 943                 kfree(vma);
 944         }
 945         return ret;
 946
 947  sharing_violation:
 948         up_write(&nommu_vma_sem);
 949         printk("Attempt to share mismatched mappings\n");
 950         kfree(vml);
 951         return -EINVAL;
 952
 953  error_getting_vma:
 954         up_write(&nommu_vma_sem);
 955         kfree(vml);
 956         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
 957                len, current->pid);
 958         show_free_areas();
 959         return -ENOMEM;
 960
 961  error_getting_vml:
 962         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
 963                len, current->pid);
 964         show_free_areas();
 965         return -ENOMEM;
 966 }
 967
 968 /*
 969  * handle mapping disposal for uClinux
 970  */
 971 static void put_vma(struct vm_area_struct *vma)
 972 {
 973         if (vma) {
 974                 down_write(&nommu_vma_sem);
 975
 976                 if (atomic_dec_and_test(&vma->vm_usage)) {
 977                         delete_nommu_vma(vma);
 978
 979                         if (vma->vm_ops && vma->vm_ops->close)
 980                                 vma->vm_ops->close(vma);
 981
 982                         /* IO memory and memory shared directly out of the pagecache from
 983                          * ramfs/tmpfs mustn't be released here */
 984                         if (vma->vm_flags & VM_MAPPED_COPY) {
 985                                 realalloc -= kobjsize((void *) vma->vm_start);
 986                                 askedalloc -= vma->vm_end - vma->vm_start;
 987                                 kfree((void *) vma->vm_start);
 988                         }
 989
 990                         realalloc -= kobjsize(vma);
 991                         askedalloc -= sizeof(*vma);
 992
 993                         if (vma->vm_file)
 994                                 fput(vma->vm_file);
 995                         kfree(vma);
 996                 }
 997
 998                 up_write(&nommu_vma_sem);
 999         }
1000 }
1001
1002 /*
1003  * release a mapping
1004  * - under NOMMU conditions the parameters must match exactly to the mapping to
1005  *   be removed
1006  */
1007 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1008 {
1009         struct vm_list_struct *vml, **parent;
1010         unsigned long end = addr + len;
1011
1012 #ifdef DEBUG
1013         printk("do_munmap:\n");
1014 #endif
1015
1016         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1017                 if ((*parent)->vma->vm_start > addr)
1018                         break;
1019                 if ((*parent)->vma->vm_start == addr &&
1020                     ((len == 0) || ((*parent)->vma->vm_end == end)))
1021                         goto found;
1022         }
1023
1024         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1025                current->pid, current->comm, (void *) addr);
1026         return -EINVAL;
1027
1028  found:
1029         vml = *parent;
1030
1031         put_vma(vml->vma);
1032
1033         *parent = vml->next;
1034         realalloc -= kobjsize(vml);
1035         askedalloc -= sizeof(*vml);
1036         kfree(vml);
1037
1038         update_hiwater_vm(mm);
1039         mm->total_vm -= len >> PAGE_SHIFT;
1040
1041 #ifdef DEBUG
1042         show_process_blocks();
1043 #endif
1044
1045         return 0;
1046 }
1047
1048 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1049 {
1050         int ret;
1051         struct mm_struct *mm = current->mm;
1052
1053         down_write(&mm->mmap_sem);
1054         ret = do_munmap(mm, addr, len);
1055         up_write(&mm->mmap_sem);
1056         return ret;
1057 }
1058
1059 /*
1060  * Release all mappings
1061  */
1062 void exit_mmap(struct mm_struct * mm)
1063 {
1064         struct vm_list_struct *tmp;
1065
1066         if (mm) {
1067 #ifdef DEBUG
1068                 printk("Exit_mmap:\n");
1069 #endif
1070
1071                 mm->total_vm = 0;
1072
1073                 while ((tmp = mm->context.vmlist)) {
1074                         mm->context.vmlist = tmp->next;
1075                         put_vma(tmp->vma);
1076
1077                         realalloc -= kobjsize(tmp);
1078                         askedalloc -= sizeof(*tmp);
1079                         kfree(tmp);
1080                 }
1081
1082 #ifdef DEBUG
1083                 show_process_blocks();
1084 #endif
1085         }
1086 }
1087
1088 unsigned long do_brk(unsigned long addr, unsigned long len)
1089 {
1090         return -ENOMEM;
1091 }
1092
1093 /*
1094  * expand (or shrink) an existing mapping, potentially moving it at the same
1095  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1096  *
1097  * under NOMMU conditions, we only permit changing a mapping's size, and only
1098  * as long as it stays within the hole allocated by the kmalloc() call in
1099  * do_mmap_pgoff() and the block is not shareable
1100  *
1101  * MREMAP_FIXED is not supported under NOMMU conditions
1102  */
1103 unsigned long do_mremap(unsigned long addr,
1104                         unsigned long old_len, unsigned long new_len,
1105                         unsigned long flags, unsigned long new_addr)
1106 {
1107         struct vm_area_struct *vma;
1108
1109         /* insanity checks first */
1110         if (new_len == 0)
1111                 return (unsigned long) -EINVAL;
1112
1113         if (flags & MREMAP_FIXED && new_addr != addr)
1114                 return (unsigned long) -EINVAL;
1115
1116         vma = find_vma_exact(current->mm, addr);
1117         if (!vma)
1118                 return (unsigned long) -EINVAL;
1119
1120         if (vma->vm_end != vma->vm_start + old_len)
1121                 return (unsigned long) -EFAULT;
1122
1123         if (vma->vm_flags & VM_MAYSHARE)
1124                 return (unsigned long) -EPERM;
1125
1126         if (new_len > kobjsize((void *) addr))
1127                 return (unsigned long) -ENOMEM;
1128
1129         /* all checks complete - do it */
1130         vma->vm_end = vma->vm_start + new_len;
1131
1132         askedalloc -= old_len;
1133         askedalloc += new_len;
1134
1135         return vma->vm_start;
1136 }
1137
1138 asmlinkage unsigned long sys_mremap(unsigned long addr,
1139         unsigned long old_len, unsigned long new_len,
1140         unsigned long flags, unsigned long new_addr)
1141 {
1142         unsigned long ret;
1143
1144         down_write(&current->mm->mmap_sem);
1145         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1146         up_write(&current->mm->mmap_sem);
1147         return ret;
1148 }
1149
1150 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1151                         unsigned int foll_flags)
1152 {
1153         return NULL;
1154 }
1155
1156 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
1157 {
1158         return NULL;
1159 }
1160
1161 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1162                 unsigned long to, unsigned long size, pgprot_t prot)
1163 {
1164         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1165         return 0;
1166 }
1167 EXPORT_SYMBOL(remap_pfn_range);
1168
1169 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1170 {
1171 }
1172
1173 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1174         unsigned long len, unsigned long pgoff, unsigned long flags)
1175 {
1176         return -ENOMEM;
1177 }
1178
1179 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1180 {
1181 }
1182
1183 void unmap_mapping_range(struct address_space *mapping,
1184                          loff_t const holebegin, loff_t const holelen,
1185                          int even_cows)
1186 {
1187 }
1188 EXPORT_SYMBOL(unmap_mapping_range);
1189
1190 /*
1191  * Check that a process has enough memory to allocate a new virtual
1192  * mapping. 0 means there is enough memory for the allocation to
1193  * succeed and -ENOMEM implies there is not.
1194  *
1195  * We currently support three overcommit policies, which are set via the
1196  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1197  *
1198  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1199  * Additional code 2002 Jul 20 by Robert Love.
1200  *
1201  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1202  *
1203  * Note this is a helper function intended to be used by LSMs which
1204  * wish to use this logic.
1205  */
1206 int __vm_enough_memory(long pages, int cap_sys_admin)
1207 {
1208         unsigned long free, allowed;
1209
1210         vm_acct_memory(pages);
1211
1212         /*
1213          * Sometimes we want to use more memory than we have
1214          */
1215         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1216                 return 0;
1217
1218         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1219                 unsigned long n;
1220
1221                 free = global_page_state(NR_FILE_PAGES);
1222                 free += nr_swap_pages;
1223
1224                 /*
1225                  * Any slabs which are created with the
1226                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1227                  * which are reclaimable, under pressure.  The dentry
1228                  * cache and most inode caches should fall into this
1229                  */
1230                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1231
1232                 /*
1233                  * Leave the last 3% for root
1234                  */
1235                 if (!cap_sys_admin)
1236                         free -= free / 32;
1237
1238                 if (free > pages)
1239                         return 0;
1240
1241                 /*
1242                  * nr_free_pages() is very expensive on large systems,
1243                  * only call if we're about to fail.
1244                  */
1245                 n = nr_free_pages();
1246
1247                 /*
1248                  * Leave reserved pages. The pages are not for anonymous pages.
1249                  */
1250                 if (n <= totalreserve_pages)
1251                         goto error;
1252                 else
1253                         n -= totalreserve_pages;
1254
1255                 /*
1256                  * Leave the last 3% for root
1257                  */
1258                 if (!cap_sys_admin)
1259                         n -= n / 32;
1260                 free += n;
1261
1262                 if (free > pages)
1263                         return 0;
1264
1265                 goto error;
1266         }
1267
1268         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1269         /*
1270          * Leave the last 3% for root
1271          */
1272         if (!cap_sys_admin)
1273                 allowed -= allowed / 32;
1274         allowed += total_swap_pages;
1275
1276         /* Don't let a single process grow too big:
1277            leave 3% of the size of this process for other processes */
1278         allowed -= current->mm->total_vm / 32;
1279
1280         /*
1281          * cast `allowed' as a signed long because vm_committed_space
1282          * sometimes has a negative value
1283          */
1284         if (atomic_read(&vm_committed_space) < (long)allowed)
1285                 return 0;
1286 error:
1287         vm_unacct_memory(pages);
1288
1289         return -ENOMEM;
1290 }
1291
1292 int in_gate_area_no_task(unsigned long addr)
1293 {
1294         return 0;
1295 }
1296
1297 struct page *filemap_nopage(struct vm_area_struct *area,
1298                         unsigned long address, int *type)
1299 {
1300         BUG();
1301         return NULL;
1302 }
1303
1304 /*
1305  * Access another process' address space.
1306  * - source/target buffer must be kernel space
1307  */
1308 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1309 {
1310         struct vm_area_struct *vma;
1311         struct mm_struct *mm;
1312
1313         if (addr + len < addr)
1314                 return 0;
1315
1316         mm = get_task_mm(tsk);
1317         if (!mm)
1318                 return 0;
1319
1320         down_read(&mm->mmap_sem);
1321
1322         /* the access must start within one of the target process's mappings */
1323         vma = find_vma(mm, addr);
1324         if (vma) {
1325                 /* don't overrun this mapping */
1326                 if (addr + len >= vma->vm_end)
1327                         len = vma->vm_end - addr;
1328
1329                 /* only read or write mappings where it is permitted */
1330                 if (write && vma->vm_flags & VM_MAYWRITE)
1331                         len -= copy_to_user((void *) addr, buf, len);
1332                 else if (!write && vma->vm_flags & VM_MAYREAD)
1333                         len -= copy_from_user(buf, (void *) addr, len);
1334                 else
1335                         len = 0;
1336         } else {
1337                 len = 0;
1338         }
1339
1340         up_read(&mm->mmap_sem);
1341         mmput(mm);
1342         return len;
1343 }