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/module.h>
  16 #include <linux/mm.h>
  17 #include <linux/mman.h>
  18 #include <linux/swap.h>
  19 #include <linux/file.h>
  20 #include <linux/highmem.h>
  21 #include <linux/pagemap.h>
  22 #include <linux/slab.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/ptrace.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/backing-dev.h>
  27 #include <linux/mount.h>
  28 #include <linux/personality.h>
  29 #include <linux/security.h>
  30 #include <linux/syscalls.h>
  31
  32 #include <asm/uaccess.h>
  33 #include <asm/tlb.h>
  34 #include <asm/tlbflush.h>
  35
  36 void *high_memory;
  37 struct page *mem_map;
  38 unsigned long max_mapnr;
  39 unsigned long num_physpages;
  40 unsigned long askedalloc, realalloc;
  41 atomic_t vm_committed_space = ATOMIC_INIT(0);
  42 int sysctl_overcommit_memory = OVERCOMMIT_GUESS; /* heuristic overcommit */
  43 int sysctl_overcommit_ratio = 50; /* default is 50% */
  44 int sysctl_max_map_count = DEFAULT_MAX_MAP_COUNT;
  45 int heap_stack_gap = 0;
  46
  47 EXPORT_SYMBOL(mem_map);
  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 /*
  58  * Handle all mappings that got truncated by a "truncate()"
  59  * system call.
  60  *
  61  * NOTE! We have to be ready to update the memory sharing
  62  * between the file and the memory map for a potential last
  63  * incomplete page.  Ugly, but necessary.
  64  */
  65 int vmtruncate(struct inode *inode, loff_t offset)
  66 {
  67         struct address_space *mapping = inode->i_mapping;
  68         unsigned long limit;
  69
  70         if (inode->i_size < offset)
  71                 goto do_expand;
  72         i_size_write(inode, offset);
  73
  74         truncate_inode_pages(mapping, offset);
  75         goto out_truncate;
  76
  77 do_expand:
  78         limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
  79         if (limit != RLIM_INFINITY && offset > limit)
  80                 goto out_sig;
  81         if (offset > inode->i_sb->s_maxbytes)
  82                 goto out;
  83         i_size_write(inode, offset);
  84
  85 out_truncate:
  86         if (inode->i_op && inode->i_op->truncate)
  87                 inode->i_op->truncate(inode);
  88         return 0;
  89 out_sig:
  90         send_sig(SIGXFSZ, current, 0);
  91 out:
  92         return -EFBIG;
  93 }
  94
  95 EXPORT_SYMBOL(vmtruncate);
  96
  97 /*
  98  * Return the total memory allocated for this pointer, not
  99  * just what the caller asked for.
 100  *
 101  * Doesn't have to be accurate, i.e. may have races.
 102  */
 103 unsigned int kobjsize(const void *objp)
 104 {
 105         struct page *page;
 106
 107         if (!objp || !((page = virt_to_page(objp))))
 108                 return 0;
 109
 110         if (PageSlab(page))
 111                 return ksize(objp);
 112
 113         BUG_ON(page->index < 0);
 114         BUG_ON(page->index >= MAX_ORDER);
 115
 116         return (PAGE_SIZE << page->index);
 117 }
 118
 119 /*
 120  * get a list of pages in an address range belonging to the specified process
 121  * and indicate the VMA that covers each page
 122  * - this is potentially dodgy as we may end incrementing the page count of a
 123  *   slab page or a secondary page from a compound page
 124  * - don't permit access to VMAs that don't support it, such as I/O mappings
 125  */
 126 int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 127         unsigned long start, int len, int write, int force,
 128         struct page **pages, struct vm_area_struct **vmas)
 129 {
 130         struct vm_area_struct *vma;
 131         unsigned long vm_flags;
 132         int i;
 133
 134         /* calculate required read or write permissions.
 135          * - if 'force' is set, we only require the "MAY" flags.
 136          */
 137         vm_flags  = write ? (VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
 138         vm_flags &= force ? (VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
 139
 140         for (i = 0; i < len; i++) {
 141                 vma = find_vma(mm, start);
 142                 if (!vma)
 143                         goto finish_or_fault;
 144
 145                 /* protect what we can, including chardevs */
 146                 if (vma->vm_flags & (VM_IO | VM_PFNMAP) ||
 147                     !(vm_flags & vma->vm_flags))
 148                         goto finish_or_fault;
 149
 150                 if (pages) {
 151                         pages[i] = virt_to_page(start);
 152                         if (pages[i])
 153                                 page_cache_get(pages[i]);
 154                 }
 155                 if (vmas)
 156                         vmas[i] = vma;
 157                 start += PAGE_SIZE;
 158         }
 159
 160         return i;
 161
 162 finish_or_fault:
 163         return i ? : -EFAULT;
 164 }
 165 EXPORT_SYMBOL(get_user_pages);
 166
 167 DEFINE_RWLOCK(vmlist_lock);
 168 struct vm_struct *vmlist;
 169
 170 void vfree(void *addr)
 171 {
 172         kfree(addr);
 173 }
 174 EXPORT_SYMBOL(vfree);
 175
 176 void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
 177 {
 178         /*
 179          *  You can't specify __GFP_HIGHMEM with kmalloc() since kmalloc()
 180          * returns only a logical address.
 181          */
 182         return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 183 }
 184 EXPORT_SYMBOL(__vmalloc);
 185
 186 struct page * vmalloc_to_page(void *addr)
 187 {
 188         return virt_to_page(addr);
 189 }
 190 EXPORT_SYMBOL(vmalloc_to_page);
 191
 192 unsigned long vmalloc_to_pfn(void *addr)
 193 {
 194         return page_to_pfn(virt_to_page(addr));
 195 }
 196 EXPORT_SYMBOL(vmalloc_to_pfn);
 197
 198 long vread(char *buf, char *addr, unsigned long count)
 199 {
 200         memcpy(buf, addr, count);
 201         return count;
 202 }
 203
 204 long vwrite(char *buf, char *addr, unsigned long count)
 205 {
 206         /* Don't allow overflow */
 207         if ((unsigned long) addr + count < count)
 208                 count = -(unsigned long) addr;
 209
 210         memcpy(addr, buf, count);
 211         return(count);
 212 }
 213
 214 /*
 215  *      vmalloc  -  allocate virtually continguos memory
 216  *
 217  *      @size:          allocation size
 218  *
 219  *      Allocate enough pages to cover @size from the page level
 220  *      allocator and map them into continguos kernel virtual space.
 221  *
 222  *      For tight control over page level allocator and protection flags
 223  *      use __vmalloc() instead.
 224  */
 225 void *vmalloc(unsigned long size)
 226 {
 227        return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL);
 228 }
 229 EXPORT_SYMBOL(vmalloc);
 230
 231 void *vmalloc_node(unsigned long size, int node)
 232 {
 233         return vmalloc(size);
 234 }
 235 EXPORT_SYMBOL(vmalloc_node);
 236
 237 /**
 238  * vmalloc_32  -  allocate virtually contiguous memory (32bit addressable)
 239  *      @size:          allocation size
 240  *
 241  *      Allocate enough 32bit PA addressable pages to cover @size from the
 242  *      page level allocator and map them into continguos kernel virtual space.
 243  */
 244 void *vmalloc_32(unsigned long size)
 245 {
 246         return __vmalloc(size, GFP_KERNEL, PAGE_KERNEL);
 247 }
 248 EXPORT_SYMBOL(vmalloc_32);
 249
 250 /**
 251  * vmalloc_32_user - allocate zeroed virtually contiguous 32bit memory
 252  *      @size:          allocation size
 253  *
 254  * The resulting memory area is 32bit addressable and zeroed so it can be
 255  * mapped to userspace without leaking data.
 256  */
 257 void *vmalloc_32_user(unsigned long size)
 258 {
 259         return __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
 260 }
 261 EXPORT_SYMBOL(vmalloc_32_user);
 262
 263 void *vmap(struct page **pages, unsigned int count, unsigned long flags, pgprot_t prot)
 264 {
 265         BUG();
 266         return NULL;
 267 }
 268 EXPORT_SYMBOL(vmap);
 269
 270 void vunmap(void *addr)
 271 {
 272         BUG();
 273 }
 274 EXPORT_SYMBOL(vunmap);
 275
 276 /*
 277  * Implement a stub for vmalloc_sync_all() if the architecture chose not to
 278  * have one.
 279  */
 280 void  __attribute__((weak)) vmalloc_sync_all(void)
 281 {
 282 }
 283
 284 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
 285                    struct page *page)
 286 {
 287         return -EINVAL;
 288 }
 289 EXPORT_SYMBOL(vm_insert_page);
 290
 291 /*
 292  *  sys_brk() for the most part doesn't need the global kernel
 293  *  lock, except when an application is doing something nasty
 294  *  like trying to un-brk an area that has already been mapped
 295  *  to a regular file.  in this case, the unmapping will need
 296  *  to invoke file system routines that need the global lock.
 297  */
 298 asmlinkage unsigned long sys_brk(unsigned long brk)
 299 {
 300         struct mm_struct *mm = current->mm;
 301
 302         if (brk < mm->start_brk || brk > mm->context.end_brk)
 303                 return mm->brk;
 304
 305         if (mm->brk == brk)
 306                 return mm->brk;
 307
 308         /*
 309          * Always allow shrinking brk
 310          */
 311         if (brk <= mm->brk) {
 312                 mm->brk = brk;
 313                 return brk;
 314         }
 315
 316         /*
 317          * Ok, looks good - let it rip.
 318          */
 319         return mm->brk = brk;
 320 }
 321
 322 #ifdef DEBUG
 323 static void show_process_blocks(void)
 324 {
 325         struct vm_list_struct *vml;
 326
 327         printk("Process blocks %d:", current->pid);
 328
 329         for (vml = &current->mm->context.vmlist; vml; vml = vml->next) {
 330                 printk(" %p: %p", vml, vml->vma);
 331                 if (vml->vma)
 332                         printk(" (%d @%lx #%d)",
 333                                kobjsize((void *) vml->vma->vm_start),
 334                                vml->vma->vm_start,
 335                                atomic_read(&vml->vma->vm_usage));
 336                 printk(vml->next ? " ->" : ".\n");
 337         }
 338 }
 339 #endif /* DEBUG */
 340
 341 /*
 342  * add a VMA into a process's mm_struct in the appropriate place in the list
 343  * - should be called with mm->mmap_sem held writelocked
 344  */
 345 static void add_vma_to_mm(struct mm_struct *mm, struct vm_list_struct *vml)
 346 {
 347         struct vm_list_struct **ppv;
 348
 349         for (ppv = &current->mm->context.vmlist; *ppv; ppv = &(*ppv)->next)
 350                 if ((*ppv)->vma->vm_start > vml->vma->vm_start)
 351                         break;
 352
 353         vml->next = *ppv;
 354         *ppv = vml;
 355 }
 356
 357 /*
 358  * look up the first VMA in which addr resides, NULL if none
 359  * - should be called with mm->mmap_sem at least held readlocked
 360  */
 361 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 362 {
 363         struct vm_list_struct *loop, *vml;
 364
 365         /* search the vm_start ordered list */
 366         vml = NULL;
 367         for (loop = mm->context.vmlist; loop; loop = loop->next) {
 368                 if (loop->vma->vm_start > addr)
 369                         break;
 370                 vml = loop;
 371         }
 372
 373         if (vml && vml->vma->vm_end > addr)
 374                 return vml->vma;
 375
 376         return NULL;
 377 }
 378 EXPORT_SYMBOL(find_vma);
 379
 380 /*
 381  * find a VMA
 382  * - we don't extend stack VMAs under NOMMU conditions
 383  */
 384 struct vm_area_struct *find_extend_vma(struct mm_struct *mm, unsigned long addr)
 385 {
 386         return find_vma(mm, addr);
 387 }
 388
 389 int expand_stack(struct vm_area_struct *vma, unsigned long address)
 390 {
 391         return -ENOMEM;
 392 }
 393
 394 /*
 395  * look up the first VMA exactly that exactly matches addr
 396  * - should be called with mm->mmap_sem at least held readlocked
 397  */
 398 static inline struct vm_area_struct *find_vma_exact(struct mm_struct *mm,
 399                                                     unsigned long addr)
 400 {
 401         struct vm_list_struct *vml;
 402
 403         /* search the vm_start ordered list */
 404         for (vml = mm->context.vmlist; vml; vml = vml->next) {
 405                 if (vml->vma->vm_start == addr)
 406                         return vml->vma;
 407                 if (vml->vma->vm_start > addr)
 408                         break;
 409         }
 410
 411         return NULL;
 412 }
 413
 414 /*
 415  * find a VMA in the global tree
 416  */
 417 static inline struct vm_area_struct *find_nommu_vma(unsigned long start)
 418 {
 419         struct vm_area_struct *vma;
 420         struct rb_node *n = nommu_vma_tree.rb_node;
 421
 422         while (n) {
 423                 vma = rb_entry(n, struct vm_area_struct, vm_rb);
 424
 425                 if (start < vma->vm_start)
 426                         n = n->rb_left;
 427                 else if (start > vma->vm_start)
 428                         n = n->rb_right;
 429                 else
 430                         return vma;
 431         }
 432
 433         return NULL;
 434 }
 435
 436 /*
 437  * add a VMA in the global tree
 438  */
 439 static void add_nommu_vma(struct vm_area_struct *vma)
 440 {
 441         struct vm_area_struct *pvma;
 442         struct address_space *mapping;
 443         struct rb_node **p = &nommu_vma_tree.rb_node;
 444         struct rb_node *parent = NULL;
 445
 446         /* add the VMA to the mapping */
 447         if (vma->vm_file) {
 448                 mapping = vma->vm_file->f_mapping;
 449
 450                 flush_dcache_mmap_lock(mapping);
 451                 vma_prio_tree_insert(vma, &mapping->i_mmap);
 452                 flush_dcache_mmap_unlock(mapping);
 453         }
 454
 455         /* add the VMA to the master list */
 456         while (*p) {
 457                 parent = *p;
 458                 pvma = rb_entry(parent, struct vm_area_struct, vm_rb);
 459
 460                 if (vma->vm_start < pvma->vm_start) {
 461                         p = &(*p)->rb_left;
 462                 }
 463                 else if (vma->vm_start > pvma->vm_start) {
 464                         p = &(*p)->rb_right;
 465                 }
 466                 else {
 467                         /* mappings are at the same address - this can only
 468                          * happen for shared-mem chardevs and shared file
 469                          * mappings backed by ramfs/tmpfs */
 470                         BUG_ON(!(pvma->vm_flags & VM_SHARED));
 471
 472                         if (vma < pvma)
 473                                 p = &(*p)->rb_left;
 474                         else if (vma > pvma)
 475                                 p = &(*p)->rb_right;
 476                         else
 477                                 BUG();
 478                 }
 479         }
 480
 481         rb_link_node(&vma->vm_rb, parent, p);
 482         rb_insert_color(&vma->vm_rb, &nommu_vma_tree);
 483 }
 484
 485 /*
 486  * delete a VMA from the global list
 487  */
 488 static void delete_nommu_vma(struct vm_area_struct *vma)
 489 {
 490         struct address_space *mapping;
 491
 492         /* remove the VMA from the mapping */
 493         if (vma->vm_file) {
 494                 mapping = vma->vm_file->f_mapping;
 495
 496                 flush_dcache_mmap_lock(mapping);
 497                 vma_prio_tree_remove(vma, &mapping->i_mmap);
 498                 flush_dcache_mmap_unlock(mapping);
 499         }
 500
 501         /* remove from the master list */
 502         rb_erase(&vma->vm_rb, &nommu_vma_tree);
 503 }
 504
 505 /*
 506  * determine whether a mapping should be permitted and, if so, what sort of
 507  * mapping we're capable of supporting
 508  */
 509 static int validate_mmap_request(struct file *file,
 510                                  unsigned long addr,
 511                                  unsigned long len,
 512                                  unsigned long prot,
 513                                  unsigned long flags,
 514                                  unsigned long pgoff,
 515                                  unsigned long *_capabilities)
 516 {
 517         unsigned long capabilities;
 518         unsigned long reqprot = prot;
 519         int ret;
 520
 521         /* do the simple checks first */
 522         if (flags & MAP_FIXED || addr) {
 523                 printk(KERN_DEBUG
 524                        "%d: Can't do fixed-address/overlay mmap of RAM\n",
 525                        current->pid);
 526                 return -EINVAL;
 527         }
 528
 529         if ((flags & MAP_TYPE) != MAP_PRIVATE &&
 530             (flags & MAP_TYPE) != MAP_SHARED)
 531                 return -EINVAL;
 532
 533         if (!len)
 534                 return -EINVAL;
 535
 536         /* Careful about overflows.. */
 537         len = PAGE_ALIGN(len);
 538         if (!len || len > TASK_SIZE)
 539                 return -ENOMEM;
 540
 541         /* offset overflow? */
 542         if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
 543                 return -EOVERFLOW;
 544
 545         if (file) {
 546                 /* validate file mapping requests */
 547                 struct address_space *mapping;
 548
 549                 /* files must support mmap */
 550                 if (!file->f_op || !file->f_op->mmap)
 551                         return -ENODEV;
 552
 553                 /* work out if what we've got could possibly be shared
 554                  * - we support chardevs that provide their own "memory"
 555                  * - we support files/blockdevs that are memory backed
 556                  */
 557                 mapping = file->f_mapping;
 558                 if (!mapping)
 559                         mapping = file->f_path.dentry->d_inode->i_mapping;
 560
 561                 capabilities = 0;
 562                 if (mapping && mapping->backing_dev_info)
 563                         capabilities = mapping->backing_dev_info->capabilities;
 564
 565                 if (!capabilities) {
 566                         /* no explicit capabilities set, so assume some
 567                          * defaults */
 568                         switch (file->f_path.dentry->d_inode->i_mode & S_IFMT) {
 569                         case S_IFREG:
 570                         case S_IFBLK:
 571                                 capabilities = BDI_CAP_MAP_COPY;
 572                                 break;
 573
 574                         case S_IFCHR:
 575                                 capabilities =
 576                                         BDI_CAP_MAP_DIRECT |
 577                                         BDI_CAP_READ_MAP |
 578                                         BDI_CAP_WRITE_MAP;
 579                                 break;
 580
 581                         default:
 582                                 return -EINVAL;
 583                         }
 584                 }
 585
 586                 /* eliminate any capabilities that we can't support on this
 587                  * device */
 588                 if (!file->f_op->get_unmapped_area)
 589                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 590                 if (!file->f_op->read)
 591                         capabilities &= ~BDI_CAP_MAP_COPY;
 592
 593                 if (flags & MAP_SHARED) {
 594                         /* do checks for writing, appending and locking */
 595                         if ((prot & PROT_WRITE) &&
 596                             !(file->f_mode & FMODE_WRITE))
 597                                 return -EACCES;
 598
 599                         if (IS_APPEND(file->f_path.dentry->d_inode) &&
 600                             (file->f_mode & FMODE_WRITE))
 601                                 return -EACCES;
 602
 603                         if (locks_verify_locked(file->f_path.dentry->d_inode))
 604                                 return -EAGAIN;
 605
 606                         if (!(capabilities & BDI_CAP_MAP_DIRECT))
 607                                 return -ENODEV;
 608
 609                         if (((prot & PROT_READ)  && !(capabilities & BDI_CAP_READ_MAP))  ||
 610                             ((prot & PROT_WRITE) && !(capabilities & BDI_CAP_WRITE_MAP)) ||
 611                             ((prot & PROT_EXEC)  && !(capabilities & BDI_CAP_EXEC_MAP))
 612                             ) {
 613                                 printk("MAP_SHARED not completely supported on !MMU\n");
 614                                 return -EINVAL;
 615                         }
 616
 617                         /* we mustn't privatise shared mappings */
 618                         capabilities &= ~BDI_CAP_MAP_COPY;
 619                 }
 620                 else {
 621                         /* we're going to read the file into private memory we
 622                          * allocate */
 623                         if (!(capabilities & BDI_CAP_MAP_COPY))
 624                                 return -ENODEV;
 625
 626                         /* we don't permit a private writable mapping to be
 627                          * shared with the backing device */
 628                         if (prot & PROT_WRITE)
 629                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 630                 }
 631
 632                 /* handle executable mappings and implied executable
 633                  * mappings */
 634                 if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
 635                         if (prot & PROT_EXEC)
 636                                 return -EPERM;
 637                 }
 638                 else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
 639                         /* handle implication of PROT_EXEC by PROT_READ */
 640                         if (current->personality & READ_IMPLIES_EXEC) {
 641                                 if (capabilities & BDI_CAP_EXEC_MAP)
 642                                         prot |= PROT_EXEC;
 643                         }
 644                 }
 645                 else if ((prot & PROT_READ) &&
 646                          (prot & PROT_EXEC) &&
 647                          !(capabilities & BDI_CAP_EXEC_MAP)
 648                          ) {
 649                         /* backing file is not executable, try to copy */
 650                         capabilities &= ~BDI_CAP_MAP_DIRECT;
 651                 }
 652         }
 653         else {
 654                 /* anonymous mappings are always memory backed and can be
 655                  * privately mapped
 656                  */
 657                 capabilities = BDI_CAP_MAP_COPY;
 658
 659                 /* handle PROT_EXEC implication by PROT_READ */
 660                 if ((prot & PROT_READ) &&
 661                     (current->personality & READ_IMPLIES_EXEC))
 662                         prot |= PROT_EXEC;
 663         }
 664
 665         /* allow the security API to have its say */
 666         ret = security_file_mmap(file, reqprot, prot, flags, addr, 0);
 667         if (ret < 0)
 668                 return ret;
 669
 670         /* looks okay */
 671         *_capabilities = capabilities;
 672         return 0;
 673 }
 674
 675 /*
 676  * we've determined that we can make the mapping, now translate what we
 677  * now know into VMA flags
 678  */
 679 static unsigned long determine_vm_flags(struct file *file,
 680                                         unsigned long prot,
 681                                         unsigned long flags,
 682                                         unsigned long capabilities)
 683 {
 684         unsigned long vm_flags;
 685
 686         vm_flags = calc_vm_prot_bits(prot) | calc_vm_flag_bits(flags);
 687         vm_flags |= VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
 688         /* vm_flags |= mm->def_flags; */
 689
 690         if (!(capabilities & BDI_CAP_MAP_DIRECT)) {
 691                 /* attempt to share read-only copies of mapped file chunks */
 692                 if (file && !(prot & PROT_WRITE))
 693                         vm_flags |= VM_MAYSHARE;
 694         }
 695         else {
 696                 /* overlay a shareable mapping on the backing device or inode
 697                  * if possible - used for chardevs, ramfs/tmpfs/shmfs and
 698                  * romfs/cramfs */
 699                 if (flags & MAP_SHARED)
 700                         vm_flags |= VM_MAYSHARE | VM_SHARED;
 701                 else if ((((vm_flags & capabilities) ^ vm_flags) & BDI_CAP_VMFLAGS) == 0)
 702                         vm_flags |= VM_MAYSHARE;
 703         }
 704
 705         /* refuse to let anyone share private mappings with this process if
 706          * it's being traced - otherwise breakpoints set in it may interfere
 707          * with another untraced process
 708          */
 709         if ((flags & MAP_PRIVATE) && (current->ptrace & PT_PTRACED))
 710                 vm_flags &= ~VM_MAYSHARE;
 711
 712         return vm_flags;
 713 }
 714
 715 /*
 716  * set up a shared mapping on a file
 717  */
 718 static int do_mmap_shared_file(struct vm_area_struct *vma, unsigned long len)
 719 {
 720         int ret;
 721
 722         ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 723         if (ret != -ENOSYS)
 724                 return ret;
 725
 726         /* getting an ENOSYS error indicates that direct mmap isn't
 727          * possible (as opposed to tried but failed) so we'll fall
 728          * through to making a private copy of the data and mapping
 729          * that if we can */
 730         return -ENODEV;
 731 }
 732
 733 /*
 734  * set up a private mapping or an anonymous shared mapping
 735  */
 736 static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
 737 {
 738         void *base;
 739         int ret;
 740
 741         /* invoke the file's mapping function so that it can keep track of
 742          * shared mappings on devices or memory
 743          * - VM_MAYSHARE will be set if it may attempt to share
 744          */
 745         if (vma->vm_file) {
 746                 ret = vma->vm_file->f_op->mmap(vma->vm_file, vma);
 747                 if (ret != -ENOSYS) {
 748                         /* shouldn't return success if we're not sharing */
 749                         BUG_ON(ret == 0 && !(vma->vm_flags & VM_MAYSHARE));
 750                         return ret; /* success or a real error */
 751                 }
 752
 753                 /* getting an ENOSYS error indicates that direct mmap isn't
 754                  * possible (as opposed to tried but failed) so we'll try to
 755                  * make a private copy of the data and map that instead */
 756         }
 757
 758         /* allocate some memory to hold the mapping
 759          * - note that this may not return a page-aligned address if the object
 760          *   we're allocating is smaller than a page
 761          */
 762         base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
 763         if (!base)
 764                 goto enomem;
 765
 766         vma->vm_start = (unsigned long) base;
 767         vma->vm_end = vma->vm_start + len;
 768         vma->vm_flags |= VM_MAPPED_COPY;
 769
 770 #ifdef WARN_ON_SLACK
 771         if (len + WARN_ON_SLACK <= kobjsize(result))
 772                 printk("Allocation of %lu bytes from process %d has %lu bytes of slack\n",
 773                        len, current->pid, kobjsize(result) - len);
 774 #endif
 775
 776         if (vma->vm_file) {
 777                 /* read the contents of a file into the copy */
 778                 mm_segment_t old_fs;
 779                 loff_t fpos;
 780
 781                 fpos = vma->vm_pgoff;
 782                 fpos <<= PAGE_SHIFT;
 783
 784                 old_fs = get_fs();
 785                 set_fs(KERNEL_DS);
 786                 ret = vma->vm_file->f_op->read(vma->vm_file, base, len, &fpos);
 787                 set_fs(old_fs);
 788
 789                 if (ret < 0)
 790                         goto error_free;
 791
 792                 /* clear the last little bit */
 793                 if (ret < len)
 794                         memset(base + ret, 0, len - ret);
 795
 796         } else {
 797                 /* if it's an anonymous mapping, then just clear it */
 798                 memset(base, 0, len);
 799         }
 800
 801         return 0;
 802
 803 error_free:
 804         kfree(base);
 805         vma->vm_start = 0;
 806         return ret;
 807
 808 enomem:
 809         printk("Allocation of length %lu from process %d failed\n",
 810                len, current->pid);
 811         show_free_areas();
 812         return -ENOMEM;
 813 }
 814
 815 /*
 816  * handle mapping creation for uClinux
 817  */
 818 unsigned long do_mmap_pgoff(struct file *file,
 819                             unsigned long addr,
 820                             unsigned long len,
 821                             unsigned long prot,
 822                             unsigned long flags,
 823                             unsigned long pgoff)
 824 {
 825         struct vm_list_struct *vml = NULL;
 826         struct vm_area_struct *vma = NULL;
 827         struct rb_node *rb;
 828         unsigned long capabilities, vm_flags;
 829         void *result;
 830         int ret;
 831
 832         /* decide whether we should attempt the mapping, and if so what sort of
 833          * mapping */
 834         ret = validate_mmap_request(file, addr, len, prot, flags, pgoff,
 835                                     &capabilities);
 836         if (ret < 0)
 837                 return ret;
 838
 839         /* we've determined that we can make the mapping, now translate what we
 840          * now know into VMA flags */
 841         vm_flags = determine_vm_flags(file, prot, flags, capabilities);
 842
 843         /* we're going to need to record the mapping if it works */
 844         vml = kzalloc(sizeof(struct vm_list_struct), GFP_KERNEL);
 845         if (!vml)
 846                 goto error_getting_vml;
 847
 848         down_write(&nommu_vma_sem);
 849
 850         /* if we want to share, we need to check for VMAs created by other
 851          * mmap() calls that overlap with our proposed mapping
 852          * - we can only share with an exact match on most regular files
 853          * - shared mappings on character devices and memory backed files are
 854          *   permitted to overlap inexactly as far as we are concerned for in
 855          *   these cases, sharing is handled in the driver or filesystem rather
 856          *   than here
 857          */
 858         if (vm_flags & VM_MAYSHARE) {
 859                 unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 860                 unsigned long vmpglen;
 861
 862                 /* suppress VMA sharing for shared regions */
 863                 if (vm_flags & VM_SHARED &&
 864                     capabilities & BDI_CAP_MAP_DIRECT)
 865                         goto dont_share_VMAs;
 866
 867                 for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) {
 868                         vma = rb_entry(rb, struct vm_area_struct, vm_rb);
 869
 870                         if (!(vma->vm_flags & VM_MAYSHARE))
 871                                 continue;
 872
 873                         /* search for overlapping mappings on the same file */
 874                         if (vma->vm_file->f_path.dentry->d_inode != file->f_path.dentry->d_inode)
 875                                 continue;
 876
 877                         if (vma->vm_pgoff >= pgoff + pglen)
 878                                 continue;
 879
 880                         vmpglen = vma->vm_end - vma->vm_start + PAGE_SIZE - 1;
 881                         vmpglen >>= PAGE_SHIFT;
 882                         if (pgoff >= vma->vm_pgoff + vmpglen)
 883                                 continue;
 884
 885                         /* handle inexactly overlapping matches between mappings */
 886                         if (vma->vm_pgoff != pgoff || vmpglen != pglen) {
 887                                 if (!(capabilities & BDI_CAP_MAP_DIRECT))
 888                                         goto sharing_violation;
 889                                 continue;
 890                         }
 891
 892                         /* we've found a VMA we can share */
 893                         atomic_inc(&vma->vm_usage);
 894
 895                         vml->vma = vma;
 896                         result = (void *) vma->vm_start;
 897                         goto shared;
 898                 }
 899
 900         dont_share_VMAs:
 901                 vma = NULL;
 902
 903                 /* obtain the address at which to make a shared mapping
 904                  * - this is the hook for quasi-memory character devices to
 905                  *   tell us the location of a shared mapping
 906                  */
 907                 if (file && file->f_op->get_unmapped_area) {
 908                         addr = file->f_op->get_unmapped_area(file, addr, len,
 909                                                              pgoff, flags);
 910                         if (IS_ERR((void *) addr)) {
 911                                 ret = addr;
 912                                 if (ret != (unsigned long) -ENOSYS)
 913                                         goto error;
 914
 915                                 /* the driver refused to tell us where to site
 916                                  * the mapping so we'll have to attempt to copy
 917                                  * it */
 918                                 ret = (unsigned long) -ENODEV;
 919                                 if (!(capabilities & BDI_CAP_MAP_COPY))
 920                                         goto error;
 921
 922                                 capabilities &= ~BDI_CAP_MAP_DIRECT;
 923                         }
 924                 }
 925         }
 926
 927         /* we're going to need a VMA struct as well */
 928         vma = kzalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
 929         if (!vma)
 930                 goto error_getting_vma;
 931
 932         INIT_LIST_HEAD(&vma->anon_vma_node);
 933         atomic_set(&vma->vm_usage, 1);
 934         if (file)
 935                 get_file(file);
 936         vma->vm_file    = file;
 937         vma->vm_flags   = vm_flags;
 938         vma->vm_start   = addr;
 939         vma->vm_end     = addr + len;
 940         vma->vm_pgoff   = pgoff;
 941
 942         vml->vma = vma;
 943
 944         /* set up the mapping */
 945         if (file && vma->vm_flags & VM_SHARED)
 946                 ret = do_mmap_shared_file(vma, len);
 947         else
 948                 ret = do_mmap_private(vma, len);
 949         if (ret < 0)
 950                 goto error;
 951
 952         /* okay... we have a mapping; now we have to register it */
 953         result = (void *) vma->vm_start;
 954
 955         if (vma->vm_flags & VM_MAPPED_COPY) {
 956                 realalloc += kobjsize(result);
 957                 askedalloc += len;
 958         }
 959
 960         realalloc += kobjsize(vma);
 961         askedalloc += sizeof(*vma);
 962
 963         current->mm->total_vm += len >> PAGE_SHIFT;
 964
 965         add_nommu_vma(vma);
 966
 967  shared:
 968         realalloc += kobjsize(vml);
 969         askedalloc += sizeof(*vml);
 970
 971         add_vma_to_mm(current->mm, vml);
 972
 973         up_write(&nommu_vma_sem);
 974
 975         if (prot & PROT_EXEC)
 976                 flush_icache_range((unsigned long) result,
 977                                    (unsigned long) result + len);
 978
 979 #ifdef DEBUG
 980         printk("do_mmap:\n");
 981         show_process_blocks();
 982 #endif
 983
 984         return (unsigned long) result;
 985
 986  error:
 987         up_write(&nommu_vma_sem);
 988         kfree(vml);
 989         if (vma) {
 990                 if (vma->vm_file)
 991                         fput(vma->vm_file);
 992                 kfree(vma);
 993         }
 994         return ret;
 995
 996  sharing_violation:
 997         up_write(&nommu_vma_sem);
 998         printk("Attempt to share mismatched mappings\n");
 999         kfree(vml);
1000         return -EINVAL;
1001
1002  error_getting_vma:
1003         up_write(&nommu_vma_sem);
1004         kfree(vml);
1005         printk("Allocation of vma for %lu byte allocation from process %d failed\n",
1006                len, current->pid);
1007         show_free_areas();
1008         return -ENOMEM;
1009
1010  error_getting_vml:
1011         printk("Allocation of vml for %lu byte allocation from process %d failed\n",
1012                len, current->pid);
1013         show_free_areas();
1014         return -ENOMEM;
1015 }
1016 EXPORT_SYMBOL(do_mmap_pgoff);
1017
1018 /*
1019  * handle mapping disposal for uClinux
1020  */
1021 static void put_vma(struct vm_area_struct *vma)
1022 {
1023         if (vma) {
1024                 down_write(&nommu_vma_sem);
1025
1026                 if (atomic_dec_and_test(&vma->vm_usage)) {
1027                         delete_nommu_vma(vma);
1028
1029                         if (vma->vm_ops && vma->vm_ops->close)
1030                                 vma->vm_ops->close(vma);
1031
1032                         /* IO memory and memory shared directly out of the pagecache from
1033                          * ramfs/tmpfs mustn't be released here */
1034                         if (vma->vm_flags & VM_MAPPED_COPY) {
1035                                 realalloc -= kobjsize((void *) vma->vm_start);
1036                                 askedalloc -= vma->vm_end - vma->vm_start;
1037                                 kfree((void *) vma->vm_start);
1038                         }
1039
1040                         realalloc -= kobjsize(vma);
1041                         askedalloc -= sizeof(*vma);
1042
1043                         if (vma->vm_file)
1044                                 fput(vma->vm_file);
1045                         kfree(vma);
1046                 }
1047
1048                 up_write(&nommu_vma_sem);
1049         }
1050 }
1051
1052 /*
1053  * release a mapping
1054  * - under NOMMU conditions the parameters must match exactly to the mapping to
1055  *   be removed
1056  */
1057 int do_munmap(struct mm_struct *mm, unsigned long addr, size_t len)
1058 {
1059         struct vm_list_struct *vml, **parent;
1060         unsigned long end = addr + len;
1061
1062 #ifdef DEBUG
1063         printk("do_munmap:\n");
1064 #endif
1065
1066         for (parent = &mm->context.vmlist; *parent; parent = &(*parent)->next) {
1067                 if ((*parent)->vma->vm_start > addr)
1068                         break;
1069                 if ((*parent)->vma->vm_start == addr &&
1070                     ((len == 0) || ((*parent)->vma->vm_end == end)))
1071                         goto found;
1072         }
1073
1074         printk("munmap of non-mmaped memory by process %d (%s): %p\n",
1075                current->pid, current->comm, (void *) addr);
1076         return -EINVAL;
1077
1078  found:
1079         vml = *parent;
1080
1081         put_vma(vml->vma);
1082
1083         *parent = vml->next;
1084         realalloc -= kobjsize(vml);
1085         askedalloc -= sizeof(*vml);
1086         kfree(vml);
1087
1088         update_hiwater_vm(mm);
1089         mm->total_vm -= len >> PAGE_SHIFT;
1090
1091 #ifdef DEBUG
1092         show_process_blocks();
1093 #endif
1094
1095         return 0;
1096 }
1097 EXPORT_SYMBOL(do_munmap);
1098
1099 asmlinkage long sys_munmap(unsigned long addr, size_t len)
1100 {
1101         int ret;
1102         struct mm_struct *mm = current->mm;
1103
1104         down_write(&mm->mmap_sem);
1105         ret = do_munmap(mm, addr, len);
1106         up_write(&mm->mmap_sem);
1107         return ret;
1108 }
1109
1110 /*
1111  * Release all mappings
1112  */
1113 void exit_mmap(struct mm_struct * mm)
1114 {
1115         struct vm_list_struct *tmp;
1116
1117         if (mm) {
1118 #ifdef DEBUG
1119                 printk("Exit_mmap:\n");
1120 #endif
1121
1122                 mm->total_vm = 0;
1123
1124                 while ((tmp = mm->context.vmlist)) {
1125                         mm->context.vmlist = tmp->next;
1126                         put_vma(tmp->vma);
1127
1128                         realalloc -= kobjsize(tmp);
1129                         askedalloc -= sizeof(*tmp);
1130                         kfree(tmp);
1131                 }
1132
1133 #ifdef DEBUG
1134                 show_process_blocks();
1135 #endif
1136         }
1137 }
1138
1139 unsigned long do_brk(unsigned long addr, unsigned long len)
1140 {
1141         return -ENOMEM;
1142 }
1143
1144 /*
1145  * expand (or shrink) an existing mapping, potentially moving it at the same
1146  * time (controlled by the MREMAP_MAYMOVE flag and available VM space)
1147  *
1148  * under NOMMU conditions, we only permit changing a mapping's size, and only
1149  * as long as it stays within the hole allocated by the kmalloc() call in
1150  * do_mmap_pgoff() and the block is not shareable
1151  *
1152  * MREMAP_FIXED is not supported under NOMMU conditions
1153  */
1154 unsigned long do_mremap(unsigned long addr,
1155                         unsigned long old_len, unsigned long new_len,
1156                         unsigned long flags, unsigned long new_addr)
1157 {
1158         struct vm_area_struct *vma;
1159
1160         /* insanity checks first */
1161         if (new_len == 0)
1162                 return (unsigned long) -EINVAL;
1163
1164         if (flags & MREMAP_FIXED && new_addr != addr)
1165                 return (unsigned long) -EINVAL;
1166
1167         vma = find_vma_exact(current->mm, addr);
1168         if (!vma)
1169                 return (unsigned long) -EINVAL;
1170
1171         if (vma->vm_end != vma->vm_start + old_len)
1172                 return (unsigned long) -EFAULT;
1173
1174         if (vma->vm_flags & VM_MAYSHARE)
1175                 return (unsigned long) -EPERM;
1176
1177         if (new_len > kobjsize((void *) addr))
1178                 return (unsigned long) -ENOMEM;
1179
1180         /* all checks complete - do it */
1181         vma->vm_end = vma->vm_start + new_len;
1182
1183         askedalloc -= old_len;
1184         askedalloc += new_len;
1185
1186         return vma->vm_start;
1187 }
1188 EXPORT_SYMBOL(do_mremap);
1189
1190 asmlinkage unsigned long sys_mremap(unsigned long addr,
1191         unsigned long old_len, unsigned long new_len,
1192         unsigned long flags, unsigned long new_addr)
1193 {
1194         unsigned long ret;
1195
1196         down_write(&current->mm->mmap_sem);
1197         ret = do_mremap(addr, old_len, new_len, flags, new_addr);
1198         up_write(&current->mm->mmap_sem);
1199         return ret;
1200 }
1201
1202 struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1203                         unsigned int foll_flags)
1204 {
1205         return NULL;
1206 }
1207
1208 int remap_pfn_range(struct vm_area_struct *vma, unsigned long from,
1209                 unsigned long to, unsigned long size, pgprot_t prot)
1210 {
1211         vma->vm_start = vma->vm_pgoff << PAGE_SHIFT;
1212         return 0;
1213 }
1214 EXPORT_SYMBOL(remap_pfn_range);
1215
1216 void swap_unplug_io_fn(struct backing_dev_info *bdi, struct page *page)
1217 {
1218 }
1219
1220 unsigned long arch_get_unmapped_area(struct file *file, unsigned long addr,
1221         unsigned long len, unsigned long pgoff, unsigned long flags)
1222 {
1223         return -ENOMEM;
1224 }
1225
1226 void arch_unmap_area(struct mm_struct *mm, unsigned long addr)
1227 {
1228 }
1229
1230 void unmap_mapping_range(struct address_space *mapping,
1231                          loff_t const holebegin, loff_t const holelen,
1232                          int even_cows)
1233 {
1234 }
1235 EXPORT_SYMBOL(unmap_mapping_range);
1236
1237 /*
1238  * ask for an unmapped area at which to create a mapping on a file
1239  */
1240 unsigned long get_unmapped_area(struct file *file, unsigned long addr,
1241                                 unsigned long len, unsigned long pgoff,
1242                                 unsigned long flags)
1243 {
1244         unsigned long (*get_area)(struct file *, unsigned long, unsigned long,
1245                                   unsigned long, unsigned long);
1246
1247         get_area = current->mm->get_unmapped_area;
1248         if (file && file->f_op && file->f_op->get_unmapped_area)
1249                 get_area = file->f_op->get_unmapped_area;
1250
1251         if (!get_area)
1252                 return -ENOSYS;
1253
1254         return get_area(file, addr, len, pgoff, flags);
1255 }
1256 EXPORT_SYMBOL(get_unmapped_area);
1257
1258 /*
1259  * Check that a process has enough memory to allocate a new virtual
1260  * mapping. 0 means there is enough memory for the allocation to
1261  * succeed and -ENOMEM implies there is not.
1262  *
1263  * We currently support three overcommit policies, which are set via the
1264  * vm.overcommit_memory sysctl.  See Documentation/vm/overcommit-accounting
1265  *
1266  * Strict overcommit modes added 2002 Feb 26 by Alan Cox.
1267  * Additional code 2002 Jul 20 by Robert Love.
1268  *
1269  * cap_sys_admin is 1 if the process has admin privileges, 0 otherwise.
1270  *
1271  * Note this is a helper function intended to be used by LSMs which
1272  * wish to use this logic.
1273  */
1274 int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admin)
1275 {
1276         unsigned long free, allowed;
1277
1278         vm_acct_memory(pages);
1279
1280         /*
1281          * Sometimes we want to use more memory than we have
1282          */
1283         if (sysctl_overcommit_memory == OVERCOMMIT_ALWAYS)
1284                 return 0;
1285
1286         if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) {
1287                 unsigned long n;
1288
1289                 free = global_page_state(NR_FILE_PAGES);
1290                 free += nr_swap_pages;
1291
1292                 /*
1293                  * Any slabs which are created with the
1294                  * SLAB_RECLAIM_ACCOUNT flag claim to have contents
1295                  * which are reclaimable, under pressure.  The dentry
1296                  * cache and most inode caches should fall into this
1297                  */
1298                 free += global_page_state(NR_SLAB_RECLAIMABLE);
1299
1300                 /*
1301                  * Leave the last 3% for root
1302                  */
1303                 if (!cap_sys_admin)
1304                         free -= free / 32;
1305
1306                 if (free > pages)
1307                         return 0;
1308
1309                 /*
1310                  * nr_free_pages() is very expensive on large systems,
1311                  * only call if we're about to fail.
1312                  */
1313                 n = nr_free_pages();
1314
1315                 /*
1316                  * Leave reserved pages. The pages are not for anonymous pages.
1317                  */
1318                 if (n <= totalreserve_pages)
1319                         goto error;
1320                 else
1321                         n -= totalreserve_pages;
1322
1323                 /*
1324                  * Leave the last 3% for root
1325                  */
1326                 if (!cap_sys_admin)
1327                         n -= n / 32;
1328                 free += n;
1329
1330                 if (free > pages)
1331                         return 0;
1332
1333                 goto error;
1334         }
1335
1336         allowed = totalram_pages * sysctl_overcommit_ratio / 100;
1337         /*
1338          * Leave the last 3% for root
1339          */
1340         if (!cap_sys_admin)
1341                 allowed -= allowed / 32;
1342         allowed += total_swap_pages;
1343
1344         /* Don't let a single process grow too big:
1345            leave 3% of the size of this process for other processes */
1346         allowed -= current->mm->total_vm / 32;
1347
1348         /*
1349          * cast `allowed' as a signed long because vm_committed_space
1350          * sometimes has a negative value
1351          */
1352         if (atomic_read(&vm_committed_space) < (long)allowed)
1353                 return 0;
1354 error:
1355         vm_unacct_memory(pages);
1356
1357         return -ENOMEM;
1358 }
1359
1360 int in_gate_area_no_task(unsigned long addr)
1361 {
1362         return 0;
1363 }
1364
1365 int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1366 {
1367         BUG();
1368         return 0;
1369 }
1370 EXPORT_SYMBOL(filemap_fault);
1371
1372 /*
1373  * Access another process' address space.
1374  * - source/target buffer must be kernel space
1375  */
1376 int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write)
1377 {
1378         struct vm_area_struct *vma;
1379         struct mm_struct *mm;
1380
1381         if (addr + len < addr)
1382                 return 0;
1383
1384         mm = get_task_mm(tsk);
1385         if (!mm)
1386                 return 0;
1387
1388         down_read(&mm->mmap_sem);
1389
1390         /* the access must start within one of the target process's mappings */
1391         vma = find_vma(mm, addr);
1392         if (vma) {
1393                 /* don't overrun this mapping */
1394                 if (addr + len >= vma->vm_end)
1395                         len = vma->vm_end - addr;
1396
1397                 /* only read or write mappings where it is permitted */
1398                 if (write && vma->vm_flags & VM_MAYWRITE)
1399                         len -= copy_to_user((void *) addr, buf, len);
1400                 else if (!write && vma->vm_flags & VM_MAYREAD)
1401                         len -= copy_from_user(buf, (void *) addr, len);
1402                 else
1403                         len = 0;
1404         } else {
1405                 len = 0;
1406         }
1407
1408         up_read(&mm->mmap_sem);
1409         mmput(mm);
1410         return len;
1411 }