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