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 EXPORT_SYMBOL(num_physpages);
  49
  50 /* list of shareable VMAs */
  51 struct rb_root nommu_vma_tree = RB_ROOT;
  52 DECLARE_RWSEM(nommu_vma_sem);
  53
  54 struct vm_operations_struct generic_file_vm_ops = {
  55 };
  56
  57 EXPORT_SYMBOL(vfree);
  58 EXPORT_SYMBOL(vmalloc_to_page);
  59 EXPORT_SYMBOL(vmalloc_32);
  60 EXPORT_SYMBOL(vmap);
  61 EXPORT_SYMBOL(vunmap);
  62
  63 /*
  64  * Handle all mappings that got truncated by a "truncate()"
  65  * system call.
  66  *
  67  * NOTE! We have to be ready to update the memory sharing
  68  * between the file and the memory map for a potential last
  69  * incomplete page.  Ugly, but necessary.
  70  */
  71 int vmtruncate(struct inode *inode, loff_t offset)
  72 {
  73         struct address_space *mapping = inode->i_mapping;
  74         unsigned long limit;
  75
  76         if (inode->i_size < offset)
  77                 goto do_expand;
  78         i_size_write(inode, offset);
  79
  80         truncate_inode_pages(mapping, offset);
  81         goto out_truncate;
  82
  83 do_expand:
  84         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
  85         if (limit != RLIM_INFINITY && offset > limit)
  86                 goto out_sig;
  87         if (offset > inode->i_sb->s_maxbytes)
  88                 goto out;
  89         i_size_write(inode, offset);
  90
  91 out_truncate:
  92         if (inode->i_op && inode->i_op->truncate)
  93                 inode->i_op->truncate(inode);
  94         return 0;
  95 out_sig:
  96         send_sig(SIGXFSZ, current, 0);
  97 out:
  98         return -EFBIG;
  99 }
 100
 101 EXPORT_SYMBOL(vmtruncate);
 102
 103 /*
 104  * Return the total memory allocated for this pointer, not
 105  * just what the caller asked for.
 106  *
 107  * Doesn't have to be accurate, i.e. may have races.
 108  */
 109 unsigned int kobjsize(const void *objp)
 110 {
 111         struct page *page;
 112
 113         if (!objp || !((page = virt_to_page(objp))))
 114                 return 0;
 115
 116         if (PageSlab(page))
 117                 return ksize(objp);
 118
 119         BUG_ON(page->index < 0);
 120         BUG_ON(page->index >= MAX_ORDER);
 121
 122         return (PAGE_SIZE << page->index);
 123 }
 124
 125 /*
 126  * get a list of pages in an address range belonging to the specified process
 127  * and indicate the VMA that covers each page
 128  * - this is potentially dodgy as we may end incrementing the page count of a
 129  *   slab page or a secondary page from a compound page
 130  * - don't permit access to VMAs that don't support it, such as I/O mappings
 131  */
 132 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 133         unsigned long start, int len, int write, int force,
 134         struct page **pages, struct vm_area_struct **vmas)
 135 {
 136         struct vm_area_struct *vma;
 137         unsigned long vm_flags;
 138         int i;
 139
 140         /* calculate required read or write permissions.
 141          * - if 'force' is set, we only require the "MAY" flags.
 142          */
 143         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 144         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 145
 146         for (i = 0; i < len; i++) {
 147                 vma = find_vma(mm, start);
 148                 if (!vma)
 149                         goto finish_or_fault;
 150
 151                 /* protect what we can, including chardevs */
 152                 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
 153                     !(vm_flags & vma->vm_flags))
 154                         goto finish_or_fault;
 155
 156                 if (pages) {
 157                         pages[i] = virt_to_page(start);
 158                         if (pages[i])
 159                                 page_cache_get(pages[i]);
 160                 }
 161                 if (vmas)
 162                         vmas[i] = vma;
 163                 start += PAGE_SIZE;
 164         }
 165
 166         return i;
 167
 168 finish_or_fault:
 169         return i ? : -EFAULT;
 170 }
 171
 172 EXPORT_SYMBOL(get_user_pages);
 173
 174 DEFINE_RWLOCK(vmlist_lock);
 175 struct vm_struct *vmlist;
 176
 177 void vfree(void *addr)
 178 {
 179         kfree(addr);
 180 }
 181
 182 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 183 {
 184         /*
 185          * kmalloc doesn't like __GFP_HIGHMEM for some reason
 186          */
 187         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 188 }
 189
 190 struct page * vmalloc_to_page(void *addr)
 191 {
 192         return virt_to_page(addr);
 193 }
 194
 195 unsigned long vmalloc_to_pfn(void *addr)
 196 {
 197         return page_to_pfn(virt_to_page(addr));
 198 }
 199
 200
 201 long vread(char *buf, char *addr, unsigned long count)
 202 {
 203         memcpy(buf, addr, count);
 204         return count;
 205 }
 206
 207 long vwrite(char *buf, char *addr, unsigned long count)
 208 {
 209         /* Don't allow overflow */
 210         if ((unsigned long) addr + count < count)
 211                 count = -(unsigned long) addr;
 212
 213         memcpy(addr, buf, count);
 214         return(count);
 215 }
 216
 217 /*
 218  *      vmalloc  -  allocate virtually continguos memory
 219  *
 220  *      @size:          allocation size
 221  *
 222  *      Allocate enough pages to cover @size from the page level
 223  *      allocator and map them into continguos kernel virtual space.
 224  *
 225  *      For tight control over page level allocator and protection flags
 226  *      use __vmalloc() instead.
 227  */
 228 void *vmalloc(unsigned long size)
 229 {
 230        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 231 }
 232 EXPORT_SYMBOL(vmalloc);
 233
 234 void *vmalloc_node(unsigned long size, int node)
 235 {
 236         return vmalloc(size);
 237 }
 238 EXPORT_SYMBOL(vmalloc_node);
 239
 240 /*
 241  *      vmalloc_32  -  allocate virtually continguos memory (32bit addressable)
 242  *
 243  *      @size:          allocation size
 244  *
 245  *      Allocate enough 32bit PA addressable pages to cover @size from the
 246  *      page level allocator and map them into continguos kernel virtual space.
 247  */
 248 void *vmalloc_32(unsigned long size)
 249 {
 250         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 251 }
 252
 253 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 254 {
 255         BUG();
 256         return NULL;
 257 }
 258
 259 void vunmap(void *addr)
 260 {
 261         BUG();
 262 }
 263
 264 /*
 265  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 266  * have one.
 267  */
 268 void  __attribute__((weak)) vmalloc_sync_all(void)
 269 {
 270 }
 271
 272 /*
 273  *  sys_brk() for the most part doesn't need the global kernel
 274  *  lock, except when an application is doing something nasty
 275  *  like trying to un-brk an area that has already been mapped
 276  *  to a regular file.  in this case, the unmapping will need
 277  *  to invoke file system routines that need the global lock.
 278  */
 279 asmlinkage unsigned long sys_brk(unsigned long brk)
 280 {
 281         struct mm_struct *mm = current->mm;
 282
 283         if (brk < mm->start_brk || brk > mm->context.end_brk)
 284                 return mm->brk;
 285
 286         if (mm->brk == brk)
 287                 return mm->brk;
 288
 289         /*
 290          * Always allow shrinking brk
 291          */
 292         if (brk <= mm->brk) {
 293                 mm->brk = brk;
 294                 return brk;
 295         }
 296
 297         /*
 298          * Ok, looks good - let it rip.
 299          */
 300         return mm->brk = brk;
 301 }
 302
 303 #ifdef DEBUG
 304 static void show_process_blocks(void)
 305 {
 306         struct vm_list_struct *vml;
 307
 308         printk("Process blocks %d:", current->pid);
 309
 310         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
 311                 printk(" %p: %p", vml, vml->vma);
 312                 if (vml->vma)
 313                         printk(" (%d @%lx #%d)",
 314                                kobjsize((void *) vml->vma->vm_start),
 315                                vml->vma->vm_start,
 316                                atomic_read(&vml->vma->vm_usage));
 317                 printk(vml->next ? " ->" : ".\n");
 318         }
 319 }
 320 #endif /* DEBUG */
 321
 322 /*
 323  * add a VMA into a process's mm_struct in the appropriate place in the list
 324  * - should be called with mm->mmap_sem held writelocked
 325  */
 326 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
 327 {
 328         struct vm_list_struct **ppv;
 329
 330         for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
 331                 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
 332                         break;
 333
 334         vml->next = *ppv;
 335         *ppv = vml;
 336 }
 337
 338 /*
 339  * look up the first VMA in which addr resides, NULL if none
 340  * - should be called with mm->mmap_sem at least held readlocked
 341  */
 342 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 343 {
 344         struct vm_list_struct *loop, *vml;
 345
 346         /* search the vm_start ordered list */
 347         vml = NULL;
 348         for (loop = mm->context.vmlist; loop; loop = loop->next) {
 349                 if (loop->vma->vm_start > addr)
 350                         break;
 351                 vml = loop;
 352         }
 353
 354         if (vml && vml->vma->vm_end > addr)
 355                 return vml->vma;
 356
 357         return NULL;
 358 }
 359 EXPORT_SYMBOL(find_vma);
 360
 361 /*
 362  * find a VMA
 363  * - we don't extend stack VMAs under NOMMU conditions
 364  */
 365 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 366 {
 367         return find_vma(mm, addr);
 368 }
 369
 370 /*
 371  * look up the first VMA exactly that exactly matches addr
 372  * - should be called with mm->mmap_sem at least held readlocked
 373  */
 374 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 375                                                     unsigned long addr)
 376 {
 377         struct vm_list_struct *vml;
 378
 379         /* search the vm_start ordered list */
 380         for (vml = mm->context.vmlist; vml; vml = vml->next) {
 381                 if (vml->vma->vm_start == addr)
 382                         return vml->vma;
 383                 if (vml->vma->vm_start > addr)
 384                         break;
 385         }
 386
 387         return NULL;
 388 }
 389
 390 /*
 391  * find a VMA in the global tree
 392  */
 393 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
 394 {
 395         struct vm_area_struct *vma;
 396         struct rb_node *n = nommu_vma_tree.rb_node;
 397
 398         while (n) {
 399                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 400
 401                 if (start < vma->vm_start)
 402                         n = n->rb_left;
 403                 else if (start > vma->vm_start)
 404                         n = n->rb_right;
 405                 else
 406                         return vma;
 407         }
 408
 409         return NULL;
 410 }
 411
 412 /*
 413  * add a VMA in the global tree
 414  */
 415 static void add_nommu_vma(struct vm_area_struct *vma)
 416 {
 417         struct vm_area_struct *pvma;
 418         struct address_space *mapping;
 419         struct rb_node **p = &nommu_vma_tree.rb_node;
 420         struct rb_node *parent = NULL;
 421
 422         /* add the VMA to the mapping */
 423         if (vma->vm_file) {
 424                 mapping = vma->vm_file->f_mapping;
 425
 426                 flush_dcache_mmap_lock(mapping);
 427                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 428                 flush_dcache_mmap_unlock(mapping);
 429         }
 430
 431         /* add the VMA to the master list */
 432         while (*p) {
 433                 parent = *p;
 434                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 435
 436                 if (vma->vm_start < pvma->vm_start) {
 437                         p = &(*p)->rb_left;
 438                 }
 439                 else if (vma->vm_start > pvma->vm_start) {
 440                         p = &(*p)->rb_right;
 441                 }
 442                 else {
 443                         /* mappings are at the same address - this can only
 444                          * happen for shared-mem chardevs and shared file
 445                          * mappings backed by ramfs/tmpfs */
 446                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
 447
 448                         if (vma < pvma)
 449                                 p = &(*p)->rb_left;
 450                         else if (vma > pvma)
 451                                 p = &(*p)->rb_right;
 452                         else
 453                                 BUG();
 454                 }
 455         }
 456
 457         rb_link_node(&vma->vm_rb, parent, p);
 458         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
 459 }
 460
 461 /*
 462  * delete a VMA from the global list
 463  */
 464 static void delete_nommu_vma(struct vm_area_struct *vma)
 465 {
 466         struct address_space *mapping;
 467
 468         /* remove the VMA from the mapping */
 469         if (vma->vm_file) {
 470                 mapping = vma->vm_file->f_mapping;
 471
 472                 flush_dcache_mmap_lock(mapping);
 473                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 474                 flush_dcache_mmap_unlock(mapping);
 475         }
 476
 477         /* remove from the master list */
 478         rb_erase(&vma->vm_rb, &nommu_vma_tree);
 479 }
 480
 481 /*
 482  * determine whether a mapping should be permitted and, if so, what sort of
 483  * mapping we're capable of supporting
 484  */
 485 static int validate_mmap_request(struct file *file,
 486                                  unsigned long addr,
 487                                  unsigned long len,
 488                                  unsigned long prot,
 489                                  unsigned long flags,
 490                                  unsigned long pgoff,
 491                                  unsigned long *_capabilities)
 492 {
 493         unsigned long capabilities;
 494         unsigned long reqprot = prot;
 495         int ret;
 496
 497         /* do the simple checks first */
 498         if (flags & MAP_FIXED || addr) {
 499                 printk(KERN_DEBUG
 500                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 501                        current->pid);
 502                 return -EINVAL;
 503         }
 504
 505         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 506             (flags & MAP_TYPE) != MAP_SHARED)
 507                 return -EINVAL;
 508
 509         if (!len)
 510                 return -EINVAL;
 511
 512         /* Careful about overflows.. */
 513         len = PAGE_ALIGN(len);
 514         if (!len || len > TASK_SIZE)
 515                 return -ENOMEM;
 516
 517         /* offset overflow? */
 518         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 519                 return -EOVERFLOW;
 520
 521         if (file) {
 522                 /* validate file mapping requests */
 523                 struct address_space *mapping;
 524
 525                 /* files must support mmap */
 526                 if (!file->f_op || !file->f_op->mmap)
 527                         return -ENODEV;
 528
 529                 /* work out if what we've got could possibly be shared
 530                  * - we support chardevs that provide their own "memory"
 531                  * - we support files/blockdevs that are memory backed
 532                  */
 533                 mapping = file->f_mapping;
 534                 if (!mapping)
 535                         mapping = file->f_path.dentry->d_inode->i_mapping;
 536
 537                 capabilities = 0;
 538                 if (mapping && mapping->backing_dev_info)
 539                         capabilities = mapping->backing_dev_info->capabilities;
 540
 541                 if (!capabilities) {
 542                         /* no explicit capabilities set, so assume some
 543                          * defaults */
 544                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
 545                         case S_IFREG:
 546                         case S_IFBLK:
 547                                 capabilities = BDI_CAP_MAP_COPY;
 548                                 break;
 549
 550                         case S_IFCHR:
 551                                 capabilities =
 552                                         BDI_CAP_MAP_DIRECT |
 553                                         BDI_CAP_READ_MAP |
 554                                         BDI_CAP_WRITE_MAP;
 555                                 break;
 556
 557                         default:
 558                                 return -EINVAL;
 559                         }
 560                 }
 561
 562                 /* eliminate any capabilities that we can't support on this
 563                  * device */
 564                 if (!file->f_op->get_unmapped_area)
 565                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 566                 if (!file->f_op->read)
 567                         capabilities &= ~BDI_CAP_MAP_COPY;
 568
 569                 if (flags & MAP_SHARED) {
 570                         /* do checks for writing, appending and locking */
 571                         if ((prot & PROT_WRITE) &&
 572                             !(file->f_mode & FMODE_WRITE))
 573                                 return -EACCES;
 574
 575                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
 576                             (file->f_mode & FMODE_WRITE))
 577                                 return -EACCES;
 578
 579                         if (locks_verify_locked(file->f_path.dentry->d_inode))
 580                                 return -EAGAIN;
 581
 582                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 583                                 return -ENODEV;
 584
 585                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
 586                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
 587                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
 588                             ) {
 589                                 printk("MAP_SHARED not completely supported on !MMU\n");
 590                                 return -EINVAL;
 591                         }
 592
 593                         /* we mustn't privatise shared mappings */
 594                         capabilities &= ~BDI_CAP_MAP_COPY;
 595                 }
 596                 else {
 597                         /* we're going to read the file into private memory we
 598                          * allocate */
 599                         if (!(capabilities & BDI_CAP_MAP_COPY))
 600                                 return -ENODEV;
 601
 602                         /* we don't permit a private writable mapping to be
 603                          * shared with the backing device */
 604                         if (prot & PROT_WRITE)
 605                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 606                 }
 607
 608                 /* handle executable mappings and implied executable
 609                  * mappings */
 610                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
 611                         if (prot & PROT_EXEC)
 612                                 return -EPERM;
 613                 }
 614                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 615                         /* handle implication of PROT_EXEC by PROT_READ */
 616                         if (current->personality & READ_IMPLIES_EXEC) {
 617                                 if (capabilities & BDI_CAP_EXEC_MAP)
 618                                         prot |= PROT_EXEC;
 619                         }
 620                 }
 621                 else if ((prot & PROT_READ) &&
 622                          (prot & PROT_EXEC) &&
 623                          !(capabilities & BDI_CAP_EXEC_MAP)
 624                          ) {
 625                         /* backing file is not executable, try to copy */
 626                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 627                 }
 628         }
 629         else {
 630                 /* anonymous mappings are always memory backed and can be
 631                  * privately mapped
 632                  */
 633                 capabilities = BDI_CAP_MAP_COPY;
 634
 635                 /* handle PROT_EXEC implication by PROT_READ */
 636                 if ((prot & PROT_READ) &&
 637                     (current->personality & READ_IMPLIES_EXEC))
 638                         prot |= PROT_EXEC;
 639         }
 640
 641         /* allow the security API to have its say */
 642         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
 643         if (ret < 0)
 644                 return ret;
 645
 646         /* looks okay */
 647         *_capabilities = capabilities;
 648         return 0;
 649 }
 650
 651 /*
 652  * we've determined that we can make the mapping, now translate what we
 653  * now know into VMA flags
 654  */
 655 static unsigned long determine_vm_flags(struct file *file,
 656                                         unsigned long prot,
 657                                         unsigned long flags,
 658                                         unsigned long capabilities)
 659 {
 660         unsigned long vm_flags;
 661
 662         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
 663         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 664         /* vm_flags |= mm->def_flags; */
 665
 666         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
 667                 /* attempt to share read-only copies of mapped file chunks */
 668                 if (file && !(prot & PROT_WRITE))
 669                         vm_flags |= VM_MAYSHARE;
 670         }
 671         else {
 672                 /* overlay a shareable mapping on the backing device or inode
 673                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 674                  * romfs/cramfs */
 675                 if (flags & MAP_SHARED)
 676                         vm_flags |= VM_MAYSHARE | VM_SHARED;
 677                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
 678                         vm_flags |= VM_MAYSHARE;
 679         }
 680
 681         /* refuse to let anyone share private mappings with this process if
 682          * it's being traced - otherwise breakpoints set in it may interfere
 683          * with another untraced process
 684          */
 685         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
 686                 vm_flags &= ~VM_MAYSHARE;
 687
 688         return vm_flags;
 689 }
 690
 691 /*
 692  * set up a shared mapping on a file
 693  */
 694 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
 695 {
 696         int ret;
 697
 698         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 699         if (ret != -ENOSYS)
 700                 return ret;
 701
 702         /* getting an ENOSYS error indicates that direct mmap isn't
 703          * possible (as opposed to tried but failed) so we'll fall
 704          * through to making a private copy of the data and mapping
 705          * that if we can */
 706         return -ENODEV;
 707 }
 708
 709 /*
 710  * set up a private mapping or an anonymous shared mapping
 711  */
 712 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
 713 {
 714         void *base;
 715         int ret;
 716
 717         /* invoke the file's mapping function so that it can keep track of
 718          * shared mappings on devices or memory
 719          * - VM_MAYSHARE will be set if it may attempt to share
 720          */
 721         if (vma->vm_file) {
 722                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 723                 if (ret != -ENOSYS) {
 724                         /* shouldn't return success if we're not sharing */
 725                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
 726                         return ret; /* success or a real error */
 727                 }
 728
 729                 /* getting an ENOSYS error indicates that direct mmap isn't
 730                  * possible (as opposed to tried but failed) so we'll try to
 731                  * make a private copy of the data and map that instead */
 732         }
 733
 734         /* allocate some memory to hold the mapping
 735          * - note that this may not return a page-aligned address if the object
 736          *   we're allocating is smaller than a page
 737          */
 738         base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
 739         if (!base)
 740                 goto enomem;
 741
 742         vma->vm_start = (unsigned long) base;
 743         vma->vm_end = vma->vm_start + len;
 744         vma->vm_flags |= VM_MAPPED_COPY;
 745
 746 #ifdef WARN_ON_SLACK
 747         if (len + WARN_ON_SLACK <= kobjsize(result))
 748                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
 749                        len, current->pid, kobjsize(result) - len);
 750 #endif
 751
 752         if (vma->vm_file) {
 753                 /* read the contents of a file into the copy */
 754                 mm_segment_t old_fs;
 755                 loff_t fpos;
 756
 757                 fpos = vma->vm_pgoff;
 758                 fpos <<= PAGE_SHIFT;
 759
 760                 old_fs = get_fs();
 761                 set_fs(KERNEL_DS);
 762                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
 763                 set_fs(old_fs);
 764
 765                 if (ret < 0)
 766                         goto error_free;
 767
 768                 /* clear the last little bit */
 769                 if (ret < len)
 770                         memset(base + ret, 0, len - ret);
 771
 772         } else {
 773                 /* if it's an anonymous mapping, then just clear it */
 774                 memset(base, 0, len);
 775         }
 776
 777         return 0;
 778
 779 error_free:
 780         kfree(base);
 781         vma->vm_start = 0;
 782         return ret;
 783
 784 enomem:
 785         printk("Allocation of length %lu from process %d failed\n",
 786                len, current->pid);
 787         show_free_areas();
 788         return -ENOMEM;
 789 }
 790
 791 /*
 792  * handle mapping creation for uClinux
 793  */
 794 unsigned long do_mmap_pgoff(struct file *file,
 795                             unsigned long addr,
 796                             unsigned long len,
 797                             unsigned long prot,
 798                             unsigned long flags,
 799                             unsigned long pgoff)
 800 {
 801         struct vm_list_struct *vml = NULL;
 802         struct vm_area_struct *vma = NULL;
 803         struct rb_node *rb;
 804         unsigned long capabilities, vm_flags;
 805         void *result;
 806         int ret;
 807
 808         /* decide whether we should attempt the mapping, and if so what sort of
 809          * mapping */
 810         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
 811                                     &capabilities);
 812         if (ret < 0)
 813                 return ret;
 814
 815         /* we've determined that we can make the mapping, now translate what we
 816          * now know into VMA flags */
 817         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
 818
 819         /* we're going to need to record the mapping if it works */
 820         vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
 821         if (!vml)
 822                 goto error_getting_vml;
 823
 824         down_write(&nommu_vma_sem);
 825
 826         /* if we want to share, we need to check for VMAs created by other
 827          * mmap() calls that overlap with our proposed mapping
 828          * - we can only share with an exact match on most regular files
 829          * - shared mappings on character devices and memory backed files are
 830          *   permitted to overlap inexactly as far as we are concerned for in
 831          *   these cases, sharing is handled in the driver or filesystem rather
 832          *   than here
 833          */
 834         if (vm_flags & VM_MAYSHARE) {
 835                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 836                 unsigned long vmpglen;
 837
 838                 /* suppress VMA sharing for shared regions */
 839                 if (vm_flags & VM_SHARED &&
 840                     capabilities & BDI_CAP_MAP_DIRECT)
 841                         goto dont_share_VMAs;
 842
 843                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
 844                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
 845
 846                         if (!(vma->vm_flags & VM_MAYSHARE))
 847                                 continue;
 848
 849                         /* search for overlapping mappings on the same file */
 850                         if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
 851                                 continue;
 852
 853                         if (vma->vm_pgoff >= pgoff + pglen)
 854                                 continue;
 855
 856                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
 857                         vmpglen >>= PAGE_SHIFT;
 858                         if (pgoff >= vma->vm_pgoff + vmpglen)
 859                                 continue;
 860
 861                         /* handle inexactly overlapping matches between mappings */
 862                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
 863                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
 864                                         goto sharing_violation;
 865                                 continue;
 866                         }
 867
 868                         /* we've found a VMA we can share */
 869                         atomic_inc(&vma->vm_usage);
 870
 871                         vml->vma = vma;
 872                         result = (void *) vma->vm_start;
 873                         goto shared;
 874                 }
 875
 876         dont_share_VMAs:
 877                 vma = NULL;
 878
 879                 /* obtain the address at which to make a shared mapping
 880                  * - this is the hook for quasi-memory character devices to
 881                  *   tell us the location of a shared mapping
 882                  */
 883                 if (file && file->f_op->get_unmapped_area) {
 884                         addr = file->f_op->get_unmapped_area(file, addr, len,
 885                                                              pgoff, flags);
 886                         if (IS_ERR((void *) addr)) {
 887                                 ret = addr;
 888                                 if (ret != (unsigned long) -ENOSYS)
 889                                         goto error;
 890
 891                                 /* the driver refused to tell us where to site
 892                                  * the mapping so we'll have to attempt to copy
 893                                  * it */
 894                                 ret = (unsigned long) -ENODEV;
 895                                 if (!(capabilities & BDI_CAP_MAP_COPY))
 896                                         goto error;
 897
 898                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 899                         }
 900                 }
 901         }
 902
 903         /* we're going to need a VMA struct as well */
 904         vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
 905         if (!vma)
 906                 goto error_getting_vma;
 907
 908         INIT_LIST_HEAD(&vma->anon_vma_node);
 909         atomic_set(&vma->vm_usage, 1);
 910         if (file)
 911                 get_file(file);
 912         vma->vm_file    = file;
 913         vma->vm_flags   = vm_flags;
 914         vma->vm_start   = addr;
 915         vma->vm_end     = addr + len;
 916         vma->vm_pgoff   = pgoff;
 917
 918         vml->vma = vma;
 919
 920         /* set up the mapping */
 921         if (file && vma->vm_flags & VM_SHARED)
 922                 ret = do_mmap_shared_file(vma, len);
 923         else
 924                 ret = do_mmap_private(vma, len);
 925         if (ret < 0)
 926                 goto error;
 927
 928         /* okay... we have a mapping; now we have to register it */
 929         result = (void *) vma->vm_start;
 930
 931         if (vma->vm_flags & VM_MAPPED_COPY) {
 932                 realalloc += kobjsize(result);
 933                 askedalloc += len;
 934         }
 935
 936         realalloc += kobjsize(vma);
 937         askedalloc += sizeof(*vma);
 938
 939         current->mm->total_vm += len >> PAGE_SHIFT;
 940
 941         add_nommu_vma(vma);
 942
 943  shared:
 944         realalloc += kobjsize(vml);
 945         askedalloc += sizeof(*vml);
 946
 947         add_vma_to_mm(current->mm, vml);
 948
 949         up_write(&nommu_vma_sem);
 950
 951         if (prot & PROT_EXEC)
 952                 flush_icache_range((unsigned long) result,
 953                                    (unsigned long) result + len);
 954
 955 #ifdef DEBUG
 956         printk("do_mmap:\n");
 957         show_process_blocks();
 958 #endif
 959
 960         return (unsigned long) result;
 961
 962  error:
 963         up_write(&nommu_vma_sem);
 964         kfree(vml);
 965         if (vma) {
 966                 if (vma->vm_file)
 967                         fput(vma->vm_file);
 968                 kfree(vma);
 969         }
 970         return ret;
 971
 972  sharing_violation:
 973         up_write(&nommu_vma_sem);
 974         printk("Attempt to share mismatched mappings\n");
 975         kfree(vml);
 976         return -EINVAL;
 977
 978  error_getting_vma:
 979         up_write(&nommu_vma_sem);
 980         kfree(vml);
 981         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
 982                len, current->pid);
 983         show_free_areas();
 984         return -ENOMEM;
 985
 986  error_getting_vml:
 987         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
 988                len, current->pid);
 989         show_free_areas();
 990         return -ENOMEM;
 991 }
 992
 993 /*
 994  * handle mapping disposal for uClinux
 995  */
 996 static void put_vma(struct vm_area_struct *vma)
 997 {
 998         if (vma) {
 999                 down_write(&nommu_vma_sem);
1000
1001                 if (atomic_dec_and_test(&vma->vm_usage)) {
1002                         delete_nommu_vma(vma);
1003
1004                         if (vma->vm_ops && vma->vm_ops->close)
1005                                 vma->vm_ops->close(vma);
1006
1007                         /* IO memory and memory shared directly out of the pagecache from
1008                          * ramfs/tmpfs mustn't be released here */
1009                         if (vma->vm_flags & VM_MAPPED_COPY) {
1010                                 realalloc -= kobjsize((void *) vma->vm_start);
1011                                 askedalloc -= vma->vm_end - vma->vm_start;
1012                                 kfree((void *) vma->vm_start);
1013                         }
1014
1015                         realalloc -= kobjsize(vma);
1016                         askedalloc -= sizeof(*vma);
1017
1018                         if (vma->vm_file)
1019                                 fput(vma->vm_file);
1020                         kfree(vma);
1021                 }
1022
1023                 up_write(&nommu_vma_sem);
1024         }
1025 }
1026
1027 /*
1028  * release a mapping
1029  * - under NOMMU conditions the parameters must match exactly to the mapping to
1030  *   be removed
1031  */
1032 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1033 {
1034         struct vm_list_struct *vml, **parent;
1035         unsigned long end = addr + len;
1036
1037 #ifdef DEBUG
1038         printk("do_munmap:\n");
1039 #endif
1040
1041         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1042                 if ((*parent)->vma->vm_start > addr)
1043                         break;
1044                 if ((*parent)->vma->vm_start == addr &&
1045                     ((len == 0) || ((*parent)->vma->vm_end == end)))
1046                         goto found;
1047         }
1048
1049         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1050                current->pid, current->comm, (void *) addr);
1051         return -EINVAL;
1052
1053  found:
1054         vml = *parent;
1055
1056         put_vma(vml->vma);
1057
1058         *parent = vml->next;
1059         realalloc -= kobjsize(vml);
1060         askedalloc -= sizeof(*vml);
1061         kfree(vml);
1062
1063         update_hiwater_vm(mm);
1064         mm->total_vm -= len >> PAGE_SHIFT;
1065
1066 #ifdef DEBUG
1067         show_process_blocks();
1068 #endif
1069
1070         return 0;
1071 }
1072
1073 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1074 {
1075         int ret;
1076         struct mm_struct *mm = current->mm;
1077
1078         down_write(&mm->mmap_sem);
1079         ret = do_munmap(mm, addr, len);
1080         up_write(&mm->mmap_sem);
1081         return ret;
1082 }
1083
1084 /*
1085  * Release all mappings
1086  */
1087 void exit_mmap(struct mm_struct * mm)
1088 {
1089         struct vm_list_struct *tmp;
1090
1091         if (mm) {
1092 #ifdef DEBUG
1093                 printk("Exit_mmap:\n");
1094 #endif
1095
1096                 mm->total_vm = 0;
1097
1098                 while ((tmp = mm->context.vmlist)) {
1099                         mm->context.vmlist = tmp->next;
1100                         put_vma(tmp->vma);
1101
1102                         realalloc -= kobjsize(tmp);
1103                         askedalloc -= sizeof(*tmp);
1104                         kfree(tmp);
1105                 }
1106
1107 #ifdef DEBUG
1108                 show_process_blocks();
1109 #endif
1110         }
1111 }
1112
1113 unsigned long do_brk(unsigned long addr, unsigned long len)
1114 {
1115         return -ENOMEM;
1116 }
1117
1118 /*
1119  * expand (or shrink) an existing mapping, potentially moving it at the same
1120  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1121  *
1122  * under NOMMU conditions, we only permit changing a mapping's size, and only
1123  * as long as it stays within the hole allocated by the kmalloc() call in
1124  * do_mmap_pgoff() and the block is not shareable
1125  *
1126  * MREMAP_FIXED is not supported under NOMMU conditions
1127  */
1128 unsigned long do_mremap(unsigned long addr,
1129                         unsigned long old_len, unsigned long new_len,
1130                         unsigned long flags, unsigned long new_addr)
1131 {
1132         struct vm_area_struct *vma;
1133
1134         /* insanity checks first */
1135         if (new_len == 0)
1136                 return (unsigned long) -EINVAL;
1137
1138         if (flags & MREMAP_FIXED && new_addr != addr)
1139                 return (unsigned long) -EINVAL;
1140
1141         vma = find_vma_exact(current->mm, addr);
1142         if (!vma)
1143                 return (unsigned long) -EINVAL;
1144
1145         if (vma->vm_end != vma->vm_start + old_len)
1146                 return (unsigned long) -EFAULT;
1147
1148         if (vma->vm_flags & VM_MAYSHARE)
1149                 return (unsigned long) -EPERM;
1150
1151         if (new_len > kobjsize((void *) addr))
1152                 return (unsigned long) -ENOMEM;
1153
1154         /* all checks complete - do it */
1155         vma->vm_end = vma->vm_start + new_len;
1156
1157         askedalloc -= old_len;
1158         askedalloc += new_len;
1159
1160         return vma->vm_start;
1161 }
1162
1163 asmlinkage unsigned long sys_mremap(unsigned long addr,
1164         unsigned long old_len, unsigned long new_len,
1165         unsigned long flags, unsigned long new_addr)
1166 {
1167         unsigned long ret;
1168
1169         down_write(&current->mm->mmap_sem);
1170         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1171         up_write(&current->mm->mmap_sem);
1172         return ret;
1173 }
1174
1175 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1176                         unsigned int foll_flags)
1177 {
1178         return NULL;
1179 }
1180
1181 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1182                 unsigned long to, unsigned long size, pgprot_t prot)
1183 {
1184         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1185         return 0;
1186 }
1187 EXPORT_SYMBOL(remap_pfn_range);
1188
1189 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1190 {
1191 }
1192
1193 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1194         unsigned long len, unsigned long pgoff, unsigned long flags)
1195 {
1196         return -ENOMEM;
1197 }
1198
1199 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1200 {
1201 }
1202
1203 void unmap_mapping_range(struct address_space *mapping,
1204                          loff_t const holebegin, loff_t const holelen,
1205                          int even_cows)
1206 {
1207 }
1208 EXPORT_SYMBOL(unmap_mapping_range);
1209
1210 /*
1211  * ask for an unmapped area at which to create a mapping on a file
1212  */
1213 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1214                                 unsigned long len, unsigned long pgoff,
1215                                 unsigned long flags)
1216 {
1217         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1218                                   unsigned long, unsigned long);
1219
1220         get_area = current->mm->get_unmapped_area;
1221         if (file && file->f_op && file->f_op->get_unmapped_area)
1222                 get_area = file->f_op->get_unmapped_area;
1223
1224         if (!get_area)
1225                 return -ENOSYS;
1226
1227         return get_area(file, addr, len, pgoff, flags);
1228 }
1229
1230 EXPORT_SYMBOL(get_unmapped_area);
1231
1232 /*
1233  * Check that a process has enough memory to allocate a new virtual
1234  * mapping. 0 means there is enough memory for the allocation to
1235  * succeed and -ENOMEM implies there is not.
1236  *
1237  * We currently support three overcommit policies, which are set via the
1238  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1239  *
1240  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1241  * Additional code 2002 Jul 20 by Robert Love.
1242  *
1243  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1244  *
1245  * Note this is a helper function intended to be used by LSMs which
1246  * wish to use this logic.
1247  */
1248 int __vm_enough_memory(long pages, int cap_sys_admin)
1249 {
1250         unsigned long free, allowed;
1251
1252         vm_acct_memory(pages);
1253
1254         /*
1255          * Sometimes we want to use more memory than we have
1256          */
1257         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1258                 return 0;
1259
1260         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1261                 unsigned long n;
1262
1263                 free = global_page_state(NR_FILE_PAGES);
1264                 free += nr_swap_pages;
1265
1266                 /*
1267                  * Any slabs which are created with the
1268                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1269                  * which are reclaimable, under pressure.  The dentry
1270                  * cache and most inode caches should fall into this
1271                  */
1272                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1273
1274                 /*
1275                  * Leave the last 3% for root
1276                  */
1277                 if (!cap_sys_admin)
1278                         free -= free / 32;
1279
1280                 if (free > pages)
1281                         return 0;
1282
1283                 /*
1284                  * nr_free_pages() is very expensive on large systems,
1285                  * only call if we're about to fail.
1286                  */
1287                 n = nr_free_pages();
1288
1289                 /*
1290                  * Leave reserved pages. The pages are not for anonymous pages.
1291                  */
1292                 if (n <= totalreserve_pages)
1293                         goto error;
1294                 else
1295                         n -= totalreserve_pages;
1296
1297                 /*
1298                  * Leave the last 3% for root
1299                  */
1300                 if (!cap_sys_admin)
1301                         n -= n / 32;
1302                 free += n;
1303
1304                 if (free > pages)
1305                         return 0;
1306
1307                 goto error;
1308         }
1309
1310         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1311         /*
1312          * Leave the last 3% for root
1313          */
1314         if (!cap_sys_admin)
1315                 allowed -= allowed / 32;
1316         allowed += total_swap_pages;
1317
1318         /* Don't let a single process grow too big:
1319            leave 3% of the size of this process for other processes */
1320         allowed -= current->mm->total_vm / 32;
1321
1322         /*
1323          * cast `allowed' as a signed long because vm_committed_space
1324          * sometimes has a negative value
1325          */
1326         if (atomic_read(&vm_committed_space) < (long)allowed)
1327                 return 0;
1328 error:
1329         vm_unacct_memory(pages);
1330
1331         return -ENOMEM;
1332 }
1333
1334 int in_gate_area_no_task(unsigned long addr)
1335 {
1336         return 0;
1337 }
1338
1339 struct page *filemap_nopage(struct vm_area_struct *area,
1340                         unsigned long address, int *type)
1341 {
1342         BUG();
1343         return NULL;
1344 }
1345
1346 /*
1347  * Access another process' address space.
1348  * - source/target buffer must be kernel space
1349  */
1350 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1351 {
1352         struct vm_area_struct *vma;
1353         struct mm_struct *mm;
1354
1355         if (addr + len < addr)
1356                 return 0;
1357
1358         mm = get_task_mm(tsk);
1359         if (!mm)
1360                 return 0;
1361
1362         down_read(&mm->mmap_sem);
1363
1364         /* the access must start within one of the target process's mappings */
1365         vma = find_vma(mm, addr);
1366         if (vma) {
1367                 /* don't overrun this mapping */
1368                 if (addr + len >= vma->vm_end)
1369                         len = vma->vm_end - addr;
1370
1371                 /* only read or write mappings where it is permitted */
1372                 if (write && vma->vm_flags & VM_MAYWRITE)
1373                         len -= copy_to_user((void *) addr, buf, len);
1374                 else if (!write && vma->vm_flags & VM_MAYREAD)
1375                         len -= copy_from_user(buf, (void *) addr, len);
1376                 else
1377                         len = 0;
1378         } else {
1379                 len = 0;
1380         }
1381
1382         up_read(&mm->mmap_sem);
1383         mmput(mm);
1384         return len;
1385 }