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(sysctl_max_map_count);
  48 EXPORT_SYMBOL(sysctl_overcommit_memory);
  49 EXPORT_SYMBOL(sysctl_overcommit_ratio);
  50 EXPORT_SYMBOL(vm_committed_space);
  51 EXPORT_SYMBOL(__vm_enough_memory);
  52
  53 /* list of shareable VMAs */
  54 struct rb_root nommu_vma_tree = RB_ROOT;
  55 DECLARE_RWSEM(nommu_vma_sem);
  56
  57 struct vm_operations_struct generic_file_vm_ops = {
  58 };
  59
  60 EXPORT_SYMBOL(vmalloc);
  61 EXPORT_SYMBOL(vfree);
  62 EXPORT_SYMBOL(vmalloc_to_page);
  63 EXPORT_SYMBOL(vmalloc_32);
  64
  65 /*
  66  * Handle all mappings that got truncated by a "truncate()"
  67  * system call.
  68  *
  69  * NOTE! We have to be ready to update the memory sharing
  70  * between the file and the memory map for a potential last
  71  * incomplete page.  Ugly, but necessary.
  72  */
  73 int vmtruncate(struct inode *inode, loff_t offset)
  74 {
  75         struct address_space *mapping = inode->i_mapping;
  76         unsigned long limit;
  77
  78         if (inode->i_size < offset)
  79                 goto do_expand;
  80         i_size_write(inode, offset);
  81
  82         truncate_inode_pages(mapping, offset);
  83         goto out_truncate;
  84
  85 do_expand:
  86         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
  87         if (limit != RLIM_INFINITY && offset > limit)
  88                 goto out_sig;
  89         if (offset > inode->i_sb->s_maxbytes)
  90                 goto out;
  91         i_size_write(inode, offset);
  92
  93 out_truncate:
  94         if (inode->i_op && inode->i_op->truncate)
  95                 inode->i_op->truncate(inode);
  96         return 0;
  97 out_sig:
  98         send_sig(SIGXFSZ, current, 0);
  99 out:
 100         return -EFBIG;
 101 }
 102
 103 EXPORT_SYMBOL(vmtruncate);
 104
 105 /*
 106  * Return the total memory allocated for this pointer, not
 107  * just what the caller asked for.
 108  *
 109  * Doesn't have to be accurate, i.e. may have races.
 110  */
 111 unsigned int kobjsize(const void *objp)
 112 {
 113         struct page *page;
 114
 115         if (!objp || !((page = virt_to_page(objp))))
 116                 return 0;
 117
 118         if (PageSlab(page))
 119                 return ksize(objp);
 120
 121         BUG_ON(page->index < 0);
 122         BUG_ON(page->index >= MAX_ORDER);
 123
 124         return (PAGE_SIZE << page->index);
 125 }
 126
 127 /*
 128  * The nommu dodgy version :-)
 129  */
 130 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 131         unsigned long start, int len, int write, int force,
 132         struct page **pages, struct vm_area_struct **vmas)
 133 {
 134         int i;
 135         static struct vm_area_struct dummy_vma;
 136
 137         for (i = 0; i < len; i++) {
 138                 if (pages) {
 139                         pages[i] = virt_to_page(start);
 140                         if (pages[i])
 141                                 page_cache_get(pages[i]);
 142                 }
 143                 if (vmas)
 144                         vmas[i] = &dummy_vma;
 145                 start += PAGE_SIZE;
 146         }
 147         return(i);
 148 }
 149
 150 EXPORT_SYMBOL(get_user_pages);
 151
 152 DEFINE_RWLOCK(vmlist_lock);
 153 struct vm_struct *vmlist;
 154
 155 void vfree(void *addr)
 156 {
 157         kfree(addr);
 158 }
 159
 160 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 161 {
 162         /*
 163          * kmalloc doesn't like __GFP_HIGHMEM for some reason
 164          */
 165         return kmalloc(size, gfp_mask & ~__GFP_HIGHMEM);
 166 }
 167
 168 struct page * vmalloc_to_page(void *addr)
 169 {
 170         return virt_to_page(addr);
 171 }
 172
 173 unsigned long vmalloc_to_pfn(void *addr)
 174 {
 175         return page_to_pfn(virt_to_page(addr));
 176 }
 177
 178
 179 long vread(char *buf, char *addr, unsigned long count)
 180 {
 181         memcpy(buf, addr, count);
 182         return count;
 183 }
 184
 185 long vwrite(char *buf, char *addr, unsigned long count)
 186 {
 187         /* Don't allow overflow */
 188         if ((unsigned long) addr + count < count)
 189                 count = -(unsigned long) addr;
 190
 191         memcpy(addr, buf, count);
 192         return(count);
 193 }
 194
 195 /*
 196  *      vmalloc  -  allocate virtually continguos memory
 197  *
 198  *      @size:          allocation size
 199  *
 200  *      Allocate enough pages to cover @size from the page level
 201  *      allocator and map them into continguos kernel virtual space.
 202  *
 203  *      For tight cotrol over page level allocator and protection flags
 204  *      use __vmalloc() instead.
 205  */
 206 void *vmalloc(unsigned long size)
 207 {
 208        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 209 }
 210
 211 /*
 212  *      vmalloc_32  -  allocate virtually continguos memory (32bit addressable)
 213  *
 214  *      @size:          allocation size
 215  *
 216  *      Allocate enough 32bit PA addressable pages to cover @size from the
 217  *      page level allocator and map them into continguos kernel virtual space.
 218  */
 219 void *vmalloc_32(unsigned long size)
 220 {
 221         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 222 }
 223
 224 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 225 {
 226         BUG();
 227         return NULL;
 228 }
 229
 230 void vunmap(void *addr)
 231 {
 232         BUG();
 233 }
 234
 235 /*
 236  *  sys_brk() for the most part doesn't need the global kernel
 237  *  lock, except when an application is doing something nasty
 238  *  like trying to un-brk an area that has already been mapped
 239  *  to a regular file.  in this case, the unmapping will need
 240  *  to invoke file system routines that need the global lock.
 241  */
 242 asmlinkage unsigned long sys_brk(unsigned long brk)
 243 {
 244         struct mm_struct *mm = current->mm;
 245
 246         if (brk < mm->start_brk || brk > mm->context.end_brk)
 247                 return mm->brk;
 248
 249         if (mm->brk == brk)
 250                 return mm->brk;
 251
 252         /*
 253          * Always allow shrinking brk
 254          */
 255         if (brk <= mm->brk) {
 256                 mm->brk = brk;
 257                 return brk;
 258         }
 259
 260         /*
 261          * Ok, looks good - let it rip.
 262          */
 263         return mm->brk = brk;
 264 }
 265
 266 #ifdef DEBUG
 267 static void show_process_blocks(void)
 268 {
 269         struct vm_list_struct *vml;
 270
 271         printk("Process blocks %d:", current->pid);
 272
 273         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
 274                 printk(" %p: %p", vml, vml->vma);
 275                 if (vml->vma)
 276                         printk(" (%d @%lx #%d)",
 277                                kobjsize((void *) vml->vma->vm_start),
 278                                vml->vma->vm_start,
 279                                atomic_read(&vml->vma->vm_usage));
 280                 printk(vml->next ? " ->" : ".\n");
 281         }
 282 }
 283 #endif /* DEBUG */
 284
 285 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
 286 {
 287         struct vm_area_struct *vma;
 288         struct rb_node *n = nommu_vma_tree.rb_node;
 289
 290         while (n) {
 291                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 292
 293                 if (start < vma->vm_start)
 294                         n = n->rb_left;
 295                 else if (start > vma->vm_start)
 296                         n = n->rb_right;
 297                 else
 298                         return vma;
 299         }
 300
 301         return NULL;
 302 }
 303
 304 static void add_nommu_vma(struct vm_area_struct *vma)
 305 {
 306         struct vm_area_struct *pvma;
 307         struct address_space *mapping;
 308         struct rb_node **p = &nommu_vma_tree.rb_node;
 309         struct rb_node *parent = NULL;
 310
 311         /* add the VMA to the mapping */
 312         if (vma->vm_file) {
 313                 mapping = vma->vm_file->f_mapping;
 314
 315                 flush_dcache_mmap_lock(mapping);
 316                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 317                 flush_dcache_mmap_unlock(mapping);
 318         }
 319
 320         /* add the VMA to the master list */
 321         while (*p) {
 322                 parent = *p;
 323                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 324
 325                 if (vma->vm_start < pvma->vm_start) {
 326                         p = &(*p)->rb_left;
 327                 }
 328                 else if (vma->vm_start > pvma->vm_start) {
 329                         p = &(*p)->rb_right;
 330                 }
 331                 else {
 332                         /* mappings are at the same address - this can only
 333                          * happen for shared-mem chardevs and shared file
 334                          * mappings backed by ramfs/tmpfs */
 335                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
 336
 337                         if (vma < pvma)
 338                                 p = &(*p)->rb_left;
 339                         else if (vma > pvma)
 340                                 p = &(*p)->rb_right;
 341                         else
 342                                 BUG();
 343                 }
 344         }
 345
 346         rb_link_node(&vma->vm_rb, parent, p);
 347         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
 348 }
 349
 350 static void delete_nommu_vma(struct vm_area_struct *vma)
 351 {
 352         struct address_space *mapping;
 353
 354         /* remove the VMA from the mapping */
 355         if (vma->vm_file) {
 356                 mapping = vma->vm_file->f_mapping;
 357
 358                 flush_dcache_mmap_lock(mapping);
 359                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 360                 flush_dcache_mmap_unlock(mapping);
 361         }
 362
 363         /* remove from the master list */
 364         rb_erase(&vma->vm_rb, &nommu_vma_tree);
 365 }
 366
 367 /*
 368  * determine whether a mapping should be permitted and, if so, what sort of
 369  * mapping we're capable of supporting
 370  */
 371 static int validate_mmap_request(struct file *file,
 372                                  unsigned long addr,
 373                                  unsigned long len,
 374                                  unsigned long prot,
 375                                  unsigned long flags,
 376                                  unsigned long pgoff,
 377                                  unsigned long *_capabilities)
 378 {
 379         unsigned long capabilities;
 380         unsigned long reqprot = prot;
 381         int ret;
 382
 383         /* do the simple checks first */
 384         if (flags & MAP_FIXED || addr) {
 385                 printk(KERN_DEBUG
 386                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 387                        current->pid);
 388                 return -EINVAL;
 389         }
 390
 391         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 392             (flags & MAP_TYPE) != MAP_SHARED)
 393                 return -EINVAL;
 394
 395         if (PAGE_ALIGN(len) == 0)
 396                 return addr;
 397
 398         if (len > TASK_SIZE)
 399                 return -EINVAL;
 400
 401         /* offset overflow? */
 402         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 403                 return -EINVAL;
 404
 405         if (file) {
 406                 /* validate file mapping requests */
 407                 struct address_space *mapping;
 408
 409                 /* files must support mmap */
 410                 if (!file->f_op || !file->f_op->mmap)
 411                         return -ENODEV;
 412
 413                 /* work out if what we've got could possibly be shared
 414                  * - we support chardevs that provide their own "memory"
 415                  * - we support files/blockdevs that are memory backed
 416                  */
 417                 mapping = file->f_mapping;
 418                 if (!mapping)
 419                         mapping = file->f_dentry->d_inode->i_mapping;
 420
 421                 capabilities = 0;
 422                 if (mapping && mapping->backing_dev_info)
 423                         capabilities = mapping->backing_dev_info->capabilities;
 424
 425                 if (!capabilities) {
 426                         /* no explicit capabilities set, so assume some
 427                          * defaults */
 428                         switch (file->f_dentry->d_inode->i_mode & S_IFMT) {
 429                         case S_IFREG:
 430                         case S_IFBLK:
 431                                 capabilities = BDI_CAP_MAP_COPY;
 432                                 break;
 433
 434                         case S_IFCHR:
 435                                 capabilities =
 436                                         BDI_CAP_MAP_DIRECT |
 437                                         BDI_CAP_READ_MAP |
 438                                         BDI_CAP_WRITE_MAP;
 439                                 break;
 440
 441                         default:
 442                                 return -EINVAL;
 443                         }
 444                 }
 445
 446                 /* eliminate any capabilities that we can't support on this
 447                  * device */
 448                 if (!file->f_op->get_unmapped_area)
 449                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 450                 if (!file->f_op->read)
 451                         capabilities &= ~BDI_CAP_MAP_COPY;
 452
 453                 if (flags & MAP_SHARED) {
 454                         /* do checks for writing, appending and locking */
 455                         if ((prot & PROT_WRITE) &&
 456                             !(file->f_mode & FMODE_WRITE))
 457                                 return -EACCES;
 458
 459                         if (IS_APPEND(file->f_dentry->d_inode) &&
 460                             (file->f_mode & FMODE_WRITE))
 461                                 return -EACCES;
 462
 463                         if (locks_verify_locked(file->f_dentry->d_inode))
 464                                 return -EAGAIN;
 465
 466                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 467                                 return -ENODEV;
 468
 469                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
 470                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
 471                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
 472                             ) {
 473                                 printk("MAP_SHARED not completely supported on !MMU\n");
 474                                 return -EINVAL;
 475                         }
 476
 477                         /* we mustn't privatise shared mappings */
 478                         capabilities &= ~BDI_CAP_MAP_COPY;
 479                 }
 480                 else {
 481                         /* we're going to read the file into private memory we
 482                          * allocate */
 483                         if (!(capabilities & BDI_CAP_MAP_COPY))
 484                                 return -ENODEV;
 485
 486                         /* we don't permit a private writable mapping to be
 487                          * shared with the backing device */
 488                         if (prot & PROT_WRITE)
 489                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 490                 }
 491
 492                 /* handle executable mappings and implied executable
 493                  * mappings */
 494                 if (file->f_vfsmnt->mnt_flags & MNT_NOEXEC) {
 495                         if (prot & PROT_EXEC)
 496                                 return -EPERM;
 497                 }
 498                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 499                         /* handle implication of PROT_EXEC by PROT_READ */
 500                         if (current->personality & READ_IMPLIES_EXEC) {
 501                                 if (capabilities & BDI_CAP_EXEC_MAP)
 502                                         prot |= PROT_EXEC;
 503                         }
 504                 }
 505                 else if ((prot & PROT_READ) &&
 506                          (prot & PROT_EXEC) &&
 507                          !(capabilities & BDI_CAP_EXEC_MAP)
 508                          ) {
 509                         /* backing file is not executable, try to copy */
 510                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 511                 }
 512         }
 513         else {
 514                 /* anonymous mappings are always memory backed and can be
 515                  * privately mapped
 516                  */
 517                 capabilities = BDI_CAP_MAP_COPY;
 518
 519                 /* handle PROT_EXEC implication by PROT_READ */
 520                 if ((prot & PROT_READ) &&
 521                     (current->personality & READ_IMPLIES_EXEC))
 522                         prot |= PROT_EXEC;
 523         }
 524
 525         /* allow the security API to have its say */
 526         ret = security_file_mmap(file, reqprot, prot, flags);
 527         if (ret < 0)
 528                 return ret;
 529
 530         /* looks okay */
 531         *_capabilities = capabilities;
 532         return 0;
 533 }
 534
 535 /*
 536  * we've determined that we can make the mapping, now translate what we
 537  * now know into VMA flags
 538  */
 539 static unsigned long determine_vm_flags(struct file *file,
 540                                         unsigned long prot,
 541                                         unsigned long flags,
 542                                         unsigned long capabilities)
 543 {
 544         unsigned long vm_flags;
 545
 546         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
 547         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 548         /* vm_flags |= mm->def_flags; */
 549
 550         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
 551                 /* attempt to share read-only copies of mapped file chunks */
 552                 if (file && !(prot & PROT_WRITE))
 553                         vm_flags |= VM_MAYSHARE;
 554         }
 555         else {
 556                 /* overlay a shareable mapping on the backing device or inode
 557                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 558                  * romfs/cramfs */
 559                 if (flags & MAP_SHARED)
 560                         vm_flags |= VM_MAYSHARE | VM_SHARED;
 561                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
 562                         vm_flags |= VM_MAYSHARE;
 563         }
 564
 565         /* refuse to let anyone share private mappings with this process if
 566          * it's being traced - otherwise breakpoints set in it may interfere
 567          * with another untraced process
 568          */
 569         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
 570                 vm_flags &= ~VM_MAYSHARE;
 571
 572         return vm_flags;
 573 }
 574
 575 /*
 576  * set up a shared mapping on a file
 577  */
 578 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
 579 {
 580         int ret;
 581
 582         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 583         if (ret != -ENOSYS)
 584                 return ret;
 585
 586         /* getting an ENOSYS error indicates that direct mmap isn't
 587          * possible (as opposed to tried but failed) so we'll fall
 588          * through to making a private copy of the data and mapping
 589          * that if we can */
 590         return -ENODEV;
 591 }
 592
 593 /*
 594  * set up a private mapping or an anonymous shared mapping
 595  */
 596 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
 597 {
 598         void *base;
 599         int ret;
 600
 601         /* invoke the file's mapping function so that it can keep track of
 602          * shared mappings on devices or memory
 603          * - VM_MAYSHARE will be set if it may attempt to share
 604          */
 605         if (vma->vm_file) {
 606                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 607                 if (ret != -ENOSYS) {
 608                         /* shouldn't return success if we're not sharing */
 609                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
 610                         return ret; /* success or a real error */
 611                 }
 612
 613                 /* getting an ENOSYS error indicates that direct mmap isn't
 614                  * possible (as opposed to tried but failed) so we'll try to
 615                  * make a private copy of the data and map that instead */
 616         }
 617
 618         /* allocate some memory to hold the mapping
 619          * - note that this may not return a page-aligned address if the object
 620          *   we're allocating is smaller than a page
 621          */
 622         base = kmalloc(len, GFP_KERNEL);
 623         if (!base)
 624                 goto enomem;
 625
 626         vma->vm_start = (unsigned long) base;
 627         vma->vm_end = vma->vm_start + len;
 628         vma->vm_flags |= VM_MAPPED_COPY;
 629
 630 #ifdef WARN_ON_SLACK
 631         if (len + WARN_ON_SLACK <= kobjsize(result))
 632                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
 633                        len, current->pid, kobjsize(result) - len);
 634 #endif
 635
 636         if (vma->vm_file) {
 637                 /* read the contents of a file into the copy */
 638                 mm_segment_t old_fs;
 639                 loff_t fpos;
 640
 641                 fpos = vma->vm_pgoff;
 642                 fpos <<= PAGE_SHIFT;
 643
 644                 old_fs = get_fs();
 645                 set_fs(KERNEL_DS);
 646                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
 647                 set_fs(old_fs);
 648
 649                 if (ret < 0)
 650                         goto error_free;
 651
 652                 /* clear the last little bit */
 653                 if (ret < len)
 654                         memset(base + ret, 0, len - ret);
 655
 656         } else {
 657                 /* if it's an anonymous mapping, then just clear it */
 658                 memset(base, 0, len);
 659         }
 660
 661         return 0;
 662
 663 error_free:
 664         kfree(base);
 665         vma->vm_start = 0;
 666         return ret;
 667
 668 enomem:
 669         printk("Allocation of length %lu from process %d failed\n",
 670                len, current->pid);
 671         show_free_areas();
 672         return -ENOMEM;
 673 }
 674
 675 /*
 676  * handle mapping creation for uClinux
 677  */
 678 unsigned long do_mmap_pgoff(struct file *file,
 679                             unsigned long addr,
 680                             unsigned long len,
 681                             unsigned long prot,
 682                             unsigned long flags,
 683                             unsigned long pgoff)
 684 {
 685         struct vm_list_struct *vml = NULL;
 686         struct vm_area_struct *vma = NULL;
 687         struct rb_node *rb;
 688         unsigned long capabilities, vm_flags;
 689         void *result;
 690         int ret;
 691
 692         /* decide whether we should attempt the mapping, and if so what sort of
 693          * mapping */
 694         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
 695                                     &capabilities);
 696         if (ret < 0)
 697                 return ret;
 698
 699         /* we've determined that we can make the mapping, now translate what we
 700          * now know into VMA flags */
 701         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
 702
 703         /* we're going to need to record the mapping if it works */
 704         vml = kmalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
 705         if (!vml)
 706                 goto error_getting_vml;
 707         memset(vml, 0, sizeof(*vml));
 708
 709         down_write(&nommu_vma_sem);
 710
 711         /* if we want to share, we need to check for VMAs created by other
 712          * mmap() calls that overlap with our proposed mapping
 713          * - we can only share with an exact match on most regular files
 714          * - shared mappings on character devices and memory backed files are
 715          *   permitted to overlap inexactly as far as we are concerned for in
 716          *   these cases, sharing is handled in the driver or filesystem rather
 717          *   than here
 718          */
 719         if (vm_flags & VM_MAYSHARE) {
 720                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 721                 unsigned long vmpglen;
 722
 723                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
 724                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
 725
 726                         if (!(vma->vm_flags & VM_MAYSHARE))
 727                                 continue;
 728
 729                         /* search for overlapping mappings on the same file */
 730                         if (vma->vm_file->f_dentry->d_inode != file->f_dentry->d_inode)
 731                                 continue;
 732
 733                         if (vma->vm_pgoff >= pgoff + pglen)
 734                                 continue;
 735
 736                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
 737                         vmpglen >>= PAGE_SHIFT;
 738                         if (pgoff >= vma->vm_pgoff + vmpglen)
 739                                 continue;
 740
 741                         /* handle inexactly overlapping matches between mappings */
 742                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
 743                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
 744                                         goto sharing_violation;
 745                                 continue;
 746                         }
 747
 748                         /* we've found a VMA we can share */
 749                         atomic_inc(&vma->vm_usage);
 750
 751                         vml->vma = vma;
 752                         result = (void *) vma->vm_start;
 753                         goto shared;
 754                 }
 755
 756                 vma = NULL;
 757
 758                 /* obtain the address at which to make a shared mapping
 759                  * - this is the hook for quasi-memory character devices to
 760                  *   tell us the location of a shared mapping
 761                  */
 762                 if (file && file->f_op->get_unmapped_area) {
 763                         addr = file->f_op->get_unmapped_area(file, addr, len,
 764                                                              pgoff, flags);
 765                         if (IS_ERR((void *) addr)) {
 766                                 ret = addr;
 767                                 if (ret != (unsigned long) -ENOSYS)
 768                                         goto error;
 769
 770                                 /* the driver refused to tell us where to site
 771                                  * the mapping so we'll have to attempt to copy
 772                                  * it */
 773                                 ret = (unsigned long) -ENODEV;
 774                                 if (!(capabilities & BDI_CAP_MAP_COPY))
 775                                         goto error;
 776
 777                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 778                         }
 779                 }
 780         }
 781
 782         /* we're going to need a VMA struct as well */
 783         vma = kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
 784         if (!vma)
 785                 goto error_getting_vma;
 786
 787         memset(vma, 0, sizeof(*vma));
 788         INIT_LIST_HEAD(&vma->anon_vma_node);
 789         atomic_set(&vma->vm_usage, 1);
 790         if (file)
 791                 get_file(file);
 792         vma->vm_file    = file;
 793         vma->vm_flags   = vm_flags;
 794         vma->vm_start   = addr;
 795         vma->vm_end     = addr + len;
 796         vma->vm_pgoff   = pgoff;
 797
 798         vml->vma = vma;
 799
 800         /* set up the mapping */
 801         if (file && vma->vm_flags & VM_SHARED)
 802                 ret = do_mmap_shared_file(vma, len);
 803         else
 804                 ret = do_mmap_private(vma, len);
 805         if (ret < 0)
 806                 goto error;
 807
 808         /* okay... we have a mapping; now we have to register it */
 809         result = (void *) vma->vm_start;
 810
 811         if (vma->vm_flags & VM_MAPPED_COPY) {
 812                 realalloc += kobjsize(result);
 813                 askedalloc += len;
 814         }
 815
 816         realalloc += kobjsize(vma);
 817         askedalloc += sizeof(*vma);
 818
 819         current->mm->total_vm += len >> PAGE_SHIFT;
 820
 821         add_nommu_vma(vma);
 822
 823  shared:
 824         realalloc += kobjsize(vml);
 825         askedalloc += sizeof(*vml);
 826
 827         vml->next = current->mm->context.vmlist;
 828         current->mm->context.vmlist = vml;
 829
 830         up_write(&nommu_vma_sem);
 831
 832         if (prot & PROT_EXEC)
 833                 flush_icache_range((unsigned long) result,
 834                                    (unsigned long) result + len);
 835
 836 #ifdef DEBUG
 837         printk("do_mmap:\n");
 838         show_process_blocks();
 839 #endif
 840
 841         return (unsigned long) result;
 842
 843  error:
 844         up_write(&nommu_vma_sem);
 845         kfree(vml);
 846         if (vma) {
 847                 fput(vma->vm_file);
 848                 kfree(vma);
 849         }
 850         return ret;
 851
 852  sharing_violation:
 853         up_write(&nommu_vma_sem);
 854         printk("Attempt to share mismatched mappings\n");
 855         kfree(vml);
 856         return -EINVAL;
 857
 858  error_getting_vma:
 859         up_write(&nommu_vma_sem);
 860         kfree(vml);
 861         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
 862                len, current->pid);
 863         show_free_areas();
 864         return -ENOMEM;
 865
 866  error_getting_vml:
 867         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
 868                len, current->pid);
 869         show_free_areas();
 870         return -ENOMEM;
 871 }
 872
 873 /*
 874  * handle mapping disposal for uClinux
 875  */
 876 static void put_vma(struct vm_area_struct *vma)
 877 {
 878         if (vma) {
 879                 down_write(&nommu_vma_sem);
 880
 881                 if (atomic_dec_and_test(&vma->vm_usage)) {
 882                         delete_nommu_vma(vma);
 883
 884                         if (vma->vm_ops && vma->vm_ops->close)
 885                                 vma->vm_ops->close(vma);
 886
 887                         /* IO memory and memory shared directly out of the pagecache from
 888                          * ramfs/tmpfs mustn't be released here */
 889                         if (vma->vm_flags & VM_MAPPED_COPY) {
 890                                 realalloc -= kobjsize((void *) vma->vm_start);
 891                                 askedalloc -= vma->vm_end - vma->vm_start;
 892                                 kfree((void *) vma->vm_start);
 893                         }
 894
 895                         realalloc -= kobjsize(vma);
 896                         askedalloc -= sizeof(*vma);
 897
 898                         if (vma->vm_file)
 899                                 fput(vma->vm_file);
 900                         kfree(vma);
 901                 }
 902
 903                 up_write(&nommu_vma_sem);
 904         }
 905 }
 906
 907 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
 908 {
 909         struct vm_list_struct *vml, **parent;
 910         unsigned long end = addr + len;
 911
 912 #ifdef DEBUG
 913         printk("do_munmap:\n");
 914 #endif
 915
 916         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next)
 917                 if ((*parent)->vma->vm_start == addr &&
 918                     ((len == 0) || ((*parent)->vma->vm_end == end)))
 919                         goto found;
 920
 921         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
 922                current->pid, current->comm, (void *) addr);
 923         return -EINVAL;
 924
 925  found:
 926         vml = *parent;
 927
 928         put_vma(vml->vma);
 929
 930         *parent = vml->next;
 931         realalloc -= kobjsize(vml);
 932         askedalloc -= sizeof(*vml);
 933         kfree(vml);
 934         mm->total_vm -= len >> PAGE_SHIFT;
 935
 936 #ifdef DEBUG
 937         show_process_blocks();
 938 #endif
 939
 940         return 0;
 941 }
 942
 943 /* Release all mmaps. */
 944 void exit_mmap(struct mm_struct * mm)
 945 {
 946         struct vm_list_struct *tmp;
 947
 948         if (mm) {
 949 #ifdef DEBUG
 950                 printk("Exit_mmap:\n");
 951 #endif
 952
 953                 mm->total_vm = 0;
 954
 955                 while ((tmp = mm->context.vmlist)) {
 956                         mm->context.vmlist = tmp->next;
 957                         put_vma(tmp->vma);
 958
 959                         realalloc -= kobjsize(tmp);
 960                         askedalloc -= sizeof(*tmp);
 961                         kfree(tmp);
 962                 }
 963
 964 #ifdef DEBUG
 965                 show_process_blocks();
 966 #endif
 967         }
 968 }
 969
 970 asmlinkage long sys_munmap(unsigned long addr, size_t len)
 971 {
 972         int ret;
 973         struct mm_struct *mm = current->mm;
 974
 975         down_write(&mm->mmap_sem);
 976         ret = do_munmap(mm, addr, len);
 977         up_write(&mm->mmap_sem);
 978         return ret;
 979 }
 980
 981 unsigned long do_brk(unsigned long addr, unsigned long len)
 982 {
 983         return -ENOMEM;
 984 }
 985
 986 /*
 987  * Expand (or shrink) an existing mapping, potentially moving it at the
 988  * same time (controlled by the MREMAP_MAYMOVE flag and available VM space)
 989  *
 990  * MREMAP_FIXED option added 5-Dec-1999 by Benjamin LaHaise
 991  * This option implies MREMAP_MAYMOVE.
 992  *
 993  * on uClinux, we only permit changing a mapping's size, and only as long as it stays within the
 994  * hole allocated by the kmalloc() call in do_mmap_pgoff() and the block is not shareable
 995  */
 996 unsigned long do_mremap(unsigned long addr,
 997                         unsigned long old_len, unsigned long new_len,
 998                         unsigned long flags, unsigned long new_addr)
 999 {
1000         struct vm_list_struct *vml = NULL;
1001
1002         /* insanity checks first */
1003         if (new_len == 0)
1004                 return (unsigned long) -EINVAL;
1005
1006         if (flags & MREMAP_FIXED && new_addr != addr)
1007                 return (unsigned long) -EINVAL;
1008
1009         for (vml = current->mm->context.vmlist; vml; vml = vml->next)
1010                 if (vml->vma->vm_start == addr)
1011                         goto found;
1012
1013         return (unsigned long) -EINVAL;
1014
1015  found:
1016         if (vml->vma->vm_end != vml->vma->vm_start + old_len)
1017                 return (unsigned long) -EFAULT;
1018
1019         if (vml->vma->vm_flags & VM_MAYSHARE)
1020                 return (unsigned long) -EPERM;
1021
1022         if (new_len > kobjsize((void *) addr))
1023                 return (unsigned long) -ENOMEM;
1024
1025         /* all checks complete - do it */
1026         vml->vma->vm_end = vml->vma->vm_start + new_len;
1027
1028         askedalloc -= old_len;
1029         askedalloc += new_len;
1030
1031         return vml->vma->vm_start;
1032 }
1033
1034 /*
1035  * Look up the first VMA which satisfies  addr < vm_end,  NULL if none
1036  */
1037 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1038 {
1039         struct vm_list_struct *vml;
1040
1041         for (vml = mm->context.vmlist; vml; vml = vml->next)
1042                 if (addr >= vml->vma->vm_start && addr < vml->vma->vm_end)
1043                         return vml->vma;
1044
1045         return NULL;
1046 }
1047
1048 EXPORT_SYMBOL(find_vma);
1049
1050 struct page * follow_page(struct mm_struct *mm, unsigned long addr, int write)
1051 {
1052         return NULL;
1053 }
1054
1055 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
1056 {
1057         return NULL;
1058 }
1059
1060 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1061                 unsigned long to, unsigned long size, pgprot_t prot)
1062 {
1063         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1064         return 0;
1065 }
1066
1067 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1068 {
1069 }
1070
1071 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1072         unsigned long len, unsigned long pgoff, unsigned long flags)
1073 {
1074         return -ENOMEM;
1075 }
1076
1077 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1078 {
1079 }
1080
1081 void update_mem_hiwater(struct task_struct *tsk)
1082 {
1083         unsigned long rss;
1084
1085         if (likely(tsk->mm)) {
1086                 rss = get_mm_rss(tsk->mm);
1087                 if (tsk->mm->hiwater_rss < rss)
1088                         tsk->mm->hiwater_rss = rss;
1089                 if (tsk->mm->hiwater_vm < tsk->mm->total_vm)
1090                         tsk->mm->hiwater_vm = tsk->mm->total_vm;
1091         }
1092 }
1093
1094 void unmap_mapping_range(struct address_space *mapping,
1095                          loff_t const holebegin, loff_t const holelen,
1096                          int even_cows)
1097 {
1098 }
1099
1100 /*
1101  * Check that a process has enough memory to allocate a new virtual
1102  * mapping. 0 means there is enough memory for the allocation to
1103  * succeed and -ENOMEM implies there is not.
1104  *
1105  * We currently support three overcommit policies, which are set via the
1106  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1107  *
1108  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1109  * Additional code 2002 Jul 20 by Robert Love.
1110  *
1111  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1112  *
1113  * Note this is a helper function intended to be used by LSMs which
1114  * wish to use this logic.
1115  */
1116 int __vm_enough_memory(long pages, int cap_sys_admin)
1117 {
1118         unsigned long free, allowed;
1119
1120         vm_acct_memory(pages);
1121
1122         /*
1123          * Sometimes we want to use more memory than we have
1124          */
1125         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1126                 return 0;
1127
1128         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1129                 unsigned long n;
1130
1131                 free = get_page_cache_size();
1132                 free += nr_swap_pages;
1133
1134                 /*
1135                  * Any slabs which are created with the
1136                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1137                  * which are reclaimable, under pressure.  The dentry
1138                  * cache and most inode caches should fall into this
1139                  */
1140                 free += atomic_read(&slab_reclaim_pages);
1141
1142                 /*
1143                  * Leave the last 3% for root
1144                  */
1145                 if (!cap_sys_admin)
1146                         free -= free / 32;
1147
1148                 if (free > pages)
1149                         return 0;
1150
1151                 /*
1152                  * nr_free_pages() is very expensive on large systems,
1153                  * only call if we're about to fail.
1154                  */
1155                 n = nr_free_pages();
1156                 if (!cap_sys_admin)
1157                         n -= n / 32;
1158                 free += n;
1159
1160                 if (free > pages)
1161                         return 0;
1162                 vm_unacct_memory(pages);
1163                 return -ENOMEM;
1164         }
1165
1166         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1167         /*
1168          * Leave the last 3% for root
1169          */
1170         if (!cap_sys_admin)
1171                 allowed -= allowed / 32;
1172         allowed += total_swap_pages;
1173
1174         /* Don't let a single process grow too big:
1175            leave 3% of the size of this process for other processes */
1176         allowed -= current->mm->total_vm / 32;
1177
1178         /*
1179          * cast `allowed' as a signed long because vm_committed_space
1180          * sometimes has a negative value
1181          */
1182         if (atomic_read(&vm_committed_space) < (long)allowed)
1183                 return 0;
1184
1185         vm_unacct_memory(pages);
1186
1187         return -ENOMEM;
1188 }
1189
1190 int in_gate_area_no_task(unsigned long addr)
1191 {
1192         return 0;
1193 }