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