drivers/gpu/drm/drm_vm.c

   1 /**
   2  * \file drm_vm.c
   3  * Memory mapping for DRM
   4  *
   5  * \author Rickard E. (Rik) Faith <faith@valinux.com>
   6  * \author Gareth Hughes <gareth@valinux.com>
   7  */
   8
   9 /*
  10  * Created: Mon Jan  4 08:58:31 1999 by faith@valinux.com
  11  *
  12  * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
  13  * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
  14  * All Rights Reserved.
  15  *
  16  * Permission is hereby granted, free of charge, to any person obtaining a
  17  * copy of this software and associated documentation files (the "Software"),
  18  * to deal in the Software without restriction, including without limitation
  19  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  20  * and/or sell copies of the Software, and to permit persons to whom the
  21  * Software is furnished to do so, subject to the following conditions:
  22  *
  23  * The above copyright notice and this permission notice (including the next
  24  * paragraph) shall be included in all copies or substantial portions of the
  25  * Software.
  26  *
  27  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  28  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  29  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  30  * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  31  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  32  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  33  * OTHER DEALINGS IN THE SOFTWARE.
  34  */
  35
  36 #include <drm/drmP.h>
  37 #include <linux/export.h>
  38 #if defined(__ia64__)
  39 #include <linux/efi.h>
  40 #include <linux/slab.h>
  41 #endif
  42
  43 static void drm_vm_open(struct vm_area_struct *vma);
  44 static void drm_vm_close(struct vm_area_struct *vma);
  45
  46 static pgprot_t drm_io_prot(struct drm_local_map *map,
  47                             struct vm_area_struct *vma)
  48 {
  49         pgprot_t tmp = vm_get_page_prot(vma->vm_flags);
  50
  51 #if defined(__i386__) || defined(__x86_64__)
  52         if (map->type == _DRM_REGISTERS && !(map->flags & _DRM_WRITE_COMBINING))
  53                 tmp = pgprot_noncached(tmp);
  54         else
  55                 tmp = pgprot_writecombine(tmp);
  56 #elif defined(__powerpc__)
  57         pgprot_val(tmp) |= _PAGE_NO_CACHE;
  58         if (map->type == _DRM_REGISTERS)
  59                 pgprot_val(tmp) |= _PAGE_GUARDED;
  60 #elif defined(__ia64__)
  61         if (efi_range_is_wc(vma->vm_start, vma->vm_end -
  62                                     vma->vm_start))
  63                 tmp = pgprot_writecombine(tmp);
  64         else
  65                 tmp = pgprot_noncached(tmp);
  66 #elif defined(__sparc__) || defined(__arm__) || defined(__mips__)
  67         tmp = pgprot_noncached(tmp);
  68 #endif
  69         return tmp;
  70 }
  71
  72 static pgprot_t drm_dma_prot(uint32_t map_type, struct vm_area_struct *vma)
  73 {
  74         pgprot_t tmp = vm_get_page_prot(vma->vm_flags);
  75
  76 #if defined(__powerpc__) && defined(CONFIG_NOT_COHERENT_CACHE)
  77         tmp |= _PAGE_NO_CACHE;
  78 #endif
  79         return tmp;
  80 }
  81
  82 /**
  83  * \c fault method for AGP virtual memory.
  84  *
  85  * \param vma virtual memory area.
  86  * \param address access address.
  87  * \return pointer to the page structure.
  88  *
  89  * Find the right map and if it's AGP memory find the real physical page to
  90  * map, get the page, increment the use count and return it.
  91  */
  92 #if __OS_HAS_AGP
  93 static int drm_do_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
  94 {
  95         struct drm_file *priv = vma->vm_file->private_data;
  96         struct drm_device *dev = priv->minor->dev;
  97         struct drm_local_map *map = NULL;
  98         struct drm_map_list *r_list;
  99         struct drm_hash_item *hash;
 100
 101         /*
 102          * Find the right map
 103          */
 104         if (!dev->agp)
 105                 goto vm_fault_error;
 106
 107         if (!dev->agp || !dev->agp->cant_use_aperture)
 108                 goto vm_fault_error;
 109
 110         if (drm_ht_find_item(&dev->map_hash, vma->vm_pgoff, &hash))
 111                 goto vm_fault_error;
 112
 113         r_list = drm_hash_entry(hash, struct drm_map_list, hash);
 114         map = r_list->map;
 115
 116         if (map && map->type == _DRM_AGP) {
 117                 /*
 118                  * Using vm_pgoff as a selector forces us to use this unusual
 119                  * addressing scheme.
 120                  */
 121                 resource_size_t offset = (unsigned long)vmf->virtual_address -
 122                         vma->vm_start;
 123                 resource_size_t baddr = map->offset + offset;
 124                 struct drm_agp_mem *agpmem;
 125                 struct page *page;
 126
 127 #ifdef __alpha__
 128                 /*
 129                  * Adjust to a bus-relative address
 130                  */
 131                 baddr -= dev->hose->mem_space->start;
 132 #endif
 133
 134                 /*
 135                  * It's AGP memory - find the real physical page to map
 136                  */
 137                 list_for_each_entry(agpmem, &dev->agp->memory, head) {
 138                         if (agpmem->bound <= baddr &&
 139                             agpmem->bound + agpmem->pages * PAGE_SIZE > baddr)
 140                                 break;
 141                 }
 142
 143                 if (&agpmem->head == &dev->agp->memory)
 144                         goto vm_fault_error;
 145
 146                 /*
 147                  * Get the page, inc the use count, and return it
 148                  */
 149                 offset = (baddr - agpmem->bound) >> PAGE_SHIFT;
 150                 page = agpmem->memory->pages[offset];
 151                 get_page(page);
 152                 vmf->page = page;
 153
 154                 DRM_DEBUG
 155                     ("baddr = 0x%llx page = 0x%p, offset = 0x%llx, count=%d\n",
 156                      (unsigned long long)baddr,
 157                      agpmem->memory->pages[offset],
 158                      (unsigned long long)offset,
 159                      page_count(page));
 160                 return 0;
 161         }
 162 vm_fault_error:
 163         return VM_FAULT_SIGBUS; /* Disallow mremap */
 164 }
 165 #else                           /* __OS_HAS_AGP */
 166 static int drm_do_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 167 {
 168         return VM_FAULT_SIGBUS;
 169 }
 170 #endif                          /* __OS_HAS_AGP */
 171
 172 /**
 173  * \c nopage method for shared virtual memory.
 174  *
 175  * \param vma virtual memory area.
 176  * \param address access address.
 177  * \return pointer to the page structure.
 178  *
 179  * Get the mapping, find the real physical page to map, get the page, and
 180  * return it.
 181  */
 182 static int drm_do_vm_shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 183 {
 184         struct drm_local_map *map = vma->vm_private_data;
 185         unsigned long offset;
 186         unsigned long i;
 187         struct page *page;
 188
 189         if (!map)
 190                 return VM_FAULT_SIGBUS; /* Nothing allocated */
 191
 192         offset = (unsigned long)vmf->virtual_address - vma->vm_start;
 193         i = (unsigned long)map->handle + offset;
 194         page = vmalloc_to_page((void *)i);
 195         if (!page)
 196                 return VM_FAULT_SIGBUS;
 197         get_page(page);
 198         vmf->page = page;
 199
 200         DRM_DEBUG("shm_fault 0x%lx\n", offset);
 201         return 0;
 202 }
 203
 204 /**
 205  * \c close method for shared virtual memory.
 206  *
 207  * \param vma virtual memory area.
 208  *
 209  * Deletes map information if we are the last
 210  * person to close a mapping and it's not in the global maplist.
 211  */
 212 static void drm_vm_shm_close(struct vm_area_struct *vma)
 213 {
 214         struct drm_file *priv = vma->vm_file->private_data;
 215         struct drm_device *dev = priv->minor->dev;
 216         struct drm_vma_entry *pt, *temp;
 217         struct drm_local_map *map;
 218         struct drm_map_list *r_list;
 219         int found_maps = 0;
 220
 221         DRM_DEBUG("0x%08lx,0x%08lx\n",
 222                   vma->vm_start, vma->vm_end - vma->vm_start);
 223
 224         map = vma->vm_private_data;
 225
 226         mutex_lock(&dev->struct_mutex);
 227         list_for_each_entry_safe(pt, temp, &dev->vmalist, head) {
 228                 if (pt->vma->vm_private_data == map)
 229                         found_maps++;
 230                 if (pt->vma == vma) {
 231                         list_del(&pt->head);
 232                         kfree(pt);
 233                 }
 234         }
 235
 236         /* We were the only map that was found */
 237         if (found_maps == 1 && map->flags & _DRM_REMOVABLE) {
 238                 /* Check to see if we are in the maplist, if we are not, then
 239                  * we delete this mappings information.
 240                  */
 241                 found_maps = 0;
 242                 list_for_each_entry(r_list, &dev->maplist, head) {
 243                         if (r_list->map == map)
 244                                 found_maps++;
 245                 }
 246
 247                 if (!found_maps) {
 248                         drm_dma_handle_t dmah;
 249
 250                         switch (map->type) {
 251                         case _DRM_REGISTERS:
 252                         case _DRM_FRAME_BUFFER:
 253                                 arch_phys_wc_del(map->mtrr);
 254                                 iounmap(map->handle);
 255                                 break;
 256                         case _DRM_SHM:
 257                                 vfree(map->handle);
 258                                 break;
 259                         case _DRM_AGP:
 260                         case _DRM_SCATTER_GATHER:
 261                                 break;
 262                         case _DRM_CONSISTENT:
 263                                 dmah.vaddr = map->handle;
 264                                 dmah.busaddr = map->offset;
 265                                 dmah.size = map->size;
 266                                 __drm_pci_free(dev, &dmah);
 267                                 break;
 268                         }
 269                         kfree(map);
 270                 }
 271         }
 272         mutex_unlock(&dev->struct_mutex);
 273 }
 274
 275 /**
 276  * \c fault method for DMA virtual memory.
 277  *
 278  * \param vma virtual memory area.
 279  * \param address access address.
 280  * \return pointer to the page structure.
 281  *
 282  * Determine the page number from the page offset and get it from drm_device_dma::pagelist.
 283  */
 284 static int drm_do_vm_dma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 285 {
 286         struct drm_file *priv = vma->vm_file->private_data;
 287         struct drm_device *dev = priv->minor->dev;
 288         struct drm_device_dma *dma = dev->dma;
 289         unsigned long offset;
 290         unsigned long page_nr;
 291         struct page *page;
 292
 293         if (!dma)
 294                 return VM_FAULT_SIGBUS; /* Error */
 295         if (!dma->pagelist)
 296                 return VM_FAULT_SIGBUS; /* Nothing allocated */
 297
 298         offset = (unsigned long)vmf->virtual_address - vma->vm_start;   /* vm_[pg]off[set] should be 0 */
 299         page_nr = offset >> PAGE_SHIFT; /* page_nr could just be vmf->pgoff */
 300         page = virt_to_page((void *)dma->pagelist[page_nr]);
 301
 302         get_page(page);
 303         vmf->page = page;
 304
 305         DRM_DEBUG("dma_fault 0x%lx (page %lu)\n", offset, page_nr);
 306         return 0;
 307 }
 308
 309 /**
 310  * \c fault method for scatter-gather virtual memory.
 311  *
 312  * \param vma virtual memory area.
 313  * \param address access address.
 314  * \return pointer to the page structure.
 315  *
 316  * Determine the map offset from the page offset and get it from drm_sg_mem::pagelist.
 317  */
 318 static int drm_do_vm_sg_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 319 {
 320         struct drm_local_map *map = vma->vm_private_data;
 321         struct drm_file *priv = vma->vm_file->private_data;
 322         struct drm_device *dev = priv->minor->dev;
 323         struct drm_sg_mem *entry = dev->sg;
 324         unsigned long offset;
 325         unsigned long map_offset;
 326         unsigned long page_offset;
 327         struct page *page;
 328
 329         if (!entry)
 330                 return VM_FAULT_SIGBUS; /* Error */
 331         if (!entry->pagelist)
 332                 return VM_FAULT_SIGBUS; /* Nothing allocated */
 333
 334         offset = (unsigned long)vmf->virtual_address - vma->vm_start;
 335         map_offset = map->offset - (unsigned long)dev->sg->virtual;
 336         page_offset = (offset >> PAGE_SHIFT) + (map_offset >> PAGE_SHIFT);
 337         page = entry->pagelist[page_offset];
 338         get_page(page);
 339         vmf->page = page;
 340
 341         return 0;
 342 }
 343
 344 static int drm_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 345 {
 346         return drm_do_vm_fault(vma, vmf);
 347 }
 348
 349 static int drm_vm_shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 350 {
 351         return drm_do_vm_shm_fault(vma, vmf);
 352 }
 353
 354 static int drm_vm_dma_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 355 {
 356         return drm_do_vm_dma_fault(vma, vmf);
 357 }
 358
 359 static int drm_vm_sg_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 360 {
 361         return drm_do_vm_sg_fault(vma, vmf);
 362 }
 363
 364 /** AGP virtual memory operations */
 365 static const struct vm_operations_struct drm_vm_ops = {
 366         .fault = drm_vm_fault,
 367         .open = drm_vm_open,
 368         .close = drm_vm_close,
 369 };
 370
 371 /** Shared virtual memory operations */
 372 static const struct vm_operations_struct drm_vm_shm_ops = {
 373         .fault = drm_vm_shm_fault,
 374         .open = drm_vm_open,
 375         .close = drm_vm_shm_close,
 376 };
 377
 378 /** DMA virtual memory operations */
 379 static const struct vm_operations_struct drm_vm_dma_ops = {
 380         .fault = drm_vm_dma_fault,
 381         .open = drm_vm_open,
 382         .close = drm_vm_close,
 383 };
 384
 385 /** Scatter-gather virtual memory operations */
 386 static const struct vm_operations_struct drm_vm_sg_ops = {
 387         .fault = drm_vm_sg_fault,
 388         .open = drm_vm_open,
 389         .close = drm_vm_close,
 390 };
 391
 392 /**
 393  * \c open method for shared virtual memory.
 394  *
 395  * \param vma virtual memory area.
 396  *
 397  * Create a new drm_vma_entry structure as the \p vma private data entry and
 398  * add it to drm_device::vmalist.
 399  */
 400 void drm_vm_open_locked(struct drm_device *dev,
 401                 struct vm_area_struct *vma)
 402 {
 403         struct drm_vma_entry *vma_entry;
 404
 405         DRM_DEBUG("0x%08lx,0x%08lx\n",
 406                   vma->vm_start, vma->vm_end - vma->vm_start);
 407
 408         vma_entry = kmalloc(sizeof(*vma_entry), GFP_KERNEL);
 409         if (vma_entry) {
 410                 vma_entry->vma = vma;
 411                 vma_entry->pid = current->pid;
 412                 list_add(&vma_entry->head, &dev->vmalist);
 413         }
 414 }
 415 EXPORT_SYMBOL_GPL(drm_vm_open_locked);
 416
 417 static void drm_vm_open(struct vm_area_struct *vma)
 418 {
 419         struct drm_file *priv = vma->vm_file->private_data;
 420         struct drm_device *dev = priv->minor->dev;
 421
 422         mutex_lock(&dev->struct_mutex);
 423         drm_vm_open_locked(dev, vma);
 424         mutex_unlock(&dev->struct_mutex);
 425 }
 426
 427 void drm_vm_close_locked(struct drm_device *dev,
 428                 struct vm_area_struct *vma)
 429 {
 430         struct drm_vma_entry *pt, *temp;
 431
 432         DRM_DEBUG("0x%08lx,0x%08lx\n",
 433                   vma->vm_start, vma->vm_end - vma->vm_start);
 434
 435         list_for_each_entry_safe(pt, temp, &dev->vmalist, head) {
 436                 if (pt->vma == vma) {
 437                         list_del(&pt->head);
 438                         kfree(pt);
 439                         break;
 440                 }
 441         }
 442 }
 443
 444 /**
 445  * \c close method for all virtual memory types.
 446  *
 447  * \param vma virtual memory area.
 448  *
 449  * Search the \p vma private data entry in drm_device::vmalist, unlink it, and
 450  * free it.
 451  */
 452 static void drm_vm_close(struct vm_area_struct *vma)
 453 {
 454         struct drm_file *priv = vma->vm_file->private_data;
 455         struct drm_device *dev = priv->minor->dev;
 456
 457         mutex_lock(&dev->struct_mutex);
 458         drm_vm_close_locked(dev, vma);
 459         mutex_unlock(&dev->struct_mutex);
 460 }
 461
 462 /**
 463  * mmap DMA memory.
 464  *
 465  * \param file_priv DRM file private.
 466  * \param vma virtual memory area.
 467  * \return zero on success or a negative number on failure.
 468  *
 469  * Sets the virtual memory area operations structure to vm_dma_ops, the file
 470  * pointer, and calls vm_open().
 471  */
 472 static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
 473 {
 474         struct drm_file *priv = filp->private_data;
 475         struct drm_device *dev;
 476         struct drm_device_dma *dma;
 477         unsigned long length = vma->vm_end - vma->vm_start;
 478
 479         dev = priv->minor->dev;
 480         dma = dev->dma;
 481         DRM_DEBUG("start = 0x%lx, end = 0x%lx, page offset = 0x%lx\n",
 482                   vma->vm_start, vma->vm_end, vma->vm_pgoff);
 483
 484         /* Length must match exact page count */
 485         if (!dma || (length >> PAGE_SHIFT) != dma->page_count) {
 486                 return -EINVAL;
 487         }
 488
 489         if (!capable(CAP_SYS_ADMIN) &&
 490             (dma->flags & _DRM_DMA_USE_PCI_RO)) {
 491                 vma->vm_flags &= ~(VM_WRITE | VM_MAYWRITE);
 492 #if defined(__i386__) || defined(__x86_64__)
 493                 pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
 494 #else
 495                 /* Ye gads this is ugly.  With more thought
 496                    we could move this up higher and use
 497                    `protection_map' instead.  */
 498                 vma->vm_page_prot =
 499                     __pgprot(pte_val
 500                              (pte_wrprotect
 501                               (__pte(pgprot_val(vma->vm_page_prot)))));
 502 #endif
 503         }
 504
 505         vma->vm_ops = &drm_vm_dma_ops;
 506
 507         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 508
 509         drm_vm_open_locked(dev, vma);
 510         return 0;
 511 }
 512
 513 static resource_size_t drm_core_get_reg_ofs(struct drm_device *dev)
 514 {
 515 #ifdef __alpha__
 516         return dev->hose->dense_mem_base;
 517 #else
 518         return 0;
 519 #endif
 520 }
 521
 522 /**
 523  * mmap DMA memory.
 524  *
 525  * \param file_priv DRM file private.
 526  * \param vma virtual memory area.
 527  * \return zero on success or a negative number on failure.
 528  *
 529  * If the virtual memory area has no offset associated with it then it's a DMA
 530  * area, so calls mmap_dma(). Otherwise searches the map in drm_device::maplist,
 531  * checks that the restricted flag is not set, sets the virtual memory operations
 532  * according to the mapping type and remaps the pages. Finally sets the file
 533  * pointer and calls vm_open().
 534  */
 535 int drm_mmap_locked(struct file *filp, struct vm_area_struct *vma)
 536 {
 537         struct drm_file *priv = filp->private_data;
 538         struct drm_device *dev = priv->minor->dev;
 539         struct drm_local_map *map = NULL;
 540         resource_size_t offset = 0;
 541         struct drm_hash_item *hash;
 542
 543         DRM_DEBUG("start = 0x%lx, end = 0x%lx, page offset = 0x%lx\n",
 544                   vma->vm_start, vma->vm_end, vma->vm_pgoff);
 545
 546         if (!priv->authenticated)
 547                 return -EACCES;
 548
 549         /* We check for "dma". On Apple's UniNorth, it's valid to have
 550          * the AGP mapped at physical address 0
 551          * --BenH.
 552          */
 553         if (!vma->vm_pgoff
 554 #if __OS_HAS_AGP
 555             && (!dev->agp
 556                 || dev->agp->agp_info.device->vendor != PCI_VENDOR_ID_APPLE)
 557 #endif
 558             )
 559                 return drm_mmap_dma(filp, vma);
 560
 561         if (drm_ht_find_item(&dev->map_hash, vma->vm_pgoff, &hash)) {
 562                 DRM_ERROR("Could not find map\n");
 563                 return -EINVAL;
 564         }
 565
 566         map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
 567         if (!map || ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN)))
 568                 return -EPERM;
 569
 570         /* Check for valid size. */
 571         if (map->size < vma->vm_end - vma->vm_start)
 572                 return -EINVAL;
 573
 574         if (!capable(CAP_SYS_ADMIN) && (map->flags & _DRM_READ_ONLY)) {
 575                 vma->vm_flags &= ~(VM_WRITE | VM_MAYWRITE);
 576 #if defined(__i386__) || defined(__x86_64__)
 577                 pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
 578 #else
 579                 /* Ye gads this is ugly.  With more thought
 580                    we could move this up higher and use
 581                    `protection_map' instead.  */
 582                 vma->vm_page_prot =
 583                     __pgprot(pte_val
 584                              (pte_wrprotect
 585                               (__pte(pgprot_val(vma->vm_page_prot)))));
 586 #endif
 587         }
 588
 589         switch (map->type) {
 590 #if !defined(__arm__)
 591         case _DRM_AGP:
 592                 if (dev->agp && dev->agp->cant_use_aperture) {
 593                         /*
 594                          * On some platforms we can't talk to bus dma address from the CPU, so for
 595                          * memory of type DRM_AGP, we'll deal with sorting out the real physical
 596                          * pages and mappings in fault()
 597                          */
 598 #if defined(__powerpc__)
 599                         pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE;
 600 #endif
 601                         vma->vm_ops = &drm_vm_ops;
 602                         break;
 603                 }
 604                 /* fall through to _DRM_FRAME_BUFFER... */
 605 #endif
 606         case _DRM_FRAME_BUFFER:
 607         case _DRM_REGISTERS:
 608                 offset = drm_core_get_reg_ofs(dev);
 609                 vma->vm_page_prot = drm_io_prot(map, vma);
 610                 if (io_remap_pfn_range(vma, vma->vm_start,
 611                                        (map->offset + offset) >> PAGE_SHIFT,
 612                                        vma->vm_end - vma->vm_start,
 613                                        vma->vm_page_prot))
 614                         return -EAGAIN;
 615                 DRM_DEBUG("   Type = %d; start = 0x%lx, end = 0x%lx,"
 616                           " offset = 0x%llx\n",
 617                           map->type,
 618                           vma->vm_start, vma->vm_end, (unsigned long long)(map->offset + offset));
 619
 620                 vma->vm_ops = &drm_vm_ops;
 621                 break;
 622         case _DRM_CONSISTENT:
 623                 /* Consistent memory is really like shared memory. But
 624                  * it's allocated in a different way, so avoid fault */
 625                 if (remap_pfn_range(vma, vma->vm_start,
 626                     page_to_pfn(virt_to_page(map->handle)),
 627                     vma->vm_end - vma->vm_start, vma->vm_page_prot))
 628                         return -EAGAIN;
 629                 vma->vm_page_prot = drm_dma_prot(map->type, vma);
 630         /* fall through to _DRM_SHM */
 631         case _DRM_SHM:
 632                 vma->vm_ops = &drm_vm_shm_ops;
 633                 vma->vm_private_data = (void *)map;
 634                 break;
 635         case _DRM_SCATTER_GATHER:
 636                 vma->vm_ops = &drm_vm_sg_ops;
 637                 vma->vm_private_data = (void *)map;
 638                 vma->vm_page_prot = drm_dma_prot(map->type, vma);
 639                 break;
 640         default:
 641                 return -EINVAL; /* This should never happen. */
 642         }
 643         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 644
 645         drm_vm_open_locked(dev, vma);
 646         return 0;
 647 }
 648
 649 int drm_mmap(struct file *filp, struct vm_area_struct *vma)
 650 {
 651         struct drm_file *priv = filp->private_data;
 652         struct drm_device *dev = priv->minor->dev;
 653         int ret;
 654
 655         if (drm_device_is_unplugged(dev))
 656                 return -ENODEV;
 657
 658         mutex_lock(&dev->struct_mutex);
 659         ret = drm_mmap_locked(filp, vma);
 660         mutex_unlock(&dev->struct_mutex);
 661
 662         return ret;
 663 }
 664 EXPORT_SYMBOL(drm_mmap);