drivers/gpu/drm/drm_gem.c

   1 /*
   2  * Copyright © 2008 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  * Authors:
  24  *    Eric Anholt <eric@anholt.net>
  25  *
  26  */
  27
  28 #include <linux/types.h>
  29 #include <linux/slab.h>
  30 #include <linux/mm.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/fs.h>
  33 #include <linux/file.h>
  34 #include <linux/module.h>
  35 #include <linux/mman.h>
  36 #include <linux/pagemap.h>
  37 #include "drmP.h"
  38
  39 /** @file drm_gem.c
  40  *
  41  * This file provides some of the base ioctls and library routines for
  42  * the graphics memory manager implemented by each device driver.
  43  *
  44  * Because various devices have different requirements in terms of
  45  * synchronization and migration strategies, implementing that is left up to
  46  * the driver, and all that the general API provides should be generic --
  47  * allocating objects, reading/writing data with the cpu, freeing objects.
  48  * Even there, platform-dependent optimizations for reading/writing data with
  49  * the CPU mean we'll likely hook those out to driver-specific calls.  However,
  50  * the DRI2 implementation wants to have at least allocate/mmap be generic.
  51  *
  52  * The goal was to have swap-backed object allocation managed through
  53  * struct file.  However, file descriptors as handles to a struct file have
  54  * two major failings:
  55  * - Process limits prevent more than 1024 or so being used at a time by
  56  *   default.
  57  * - Inability to allocate high fds will aggravate the X Server's select()
  58  *   handling, and likely that of many GL client applications as well.
  59  *
  60  * This led to a plan of using our own integer IDs (called handles, following
  61  * DRM terminology) to mimic fds, and implement the fd syscalls we need as
  62  * ioctls.  The objects themselves will still include the struct file so
  63  * that we can transition to fds if the required kernel infrastructure shows
  64  * up at a later date, and as our interface with shmfs for memory allocation.
  65  */
  66
  67 /*
  68  * We make up offsets for buffer objects so we can recognize them at
  69  * mmap time.
  70  */
  71 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFFUL >> PAGE_SHIFT) + 1)
  72 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFFUL >> PAGE_SHIFT) * 16)
  73
  74 /**
  75  * Initialize the GEM device fields
  76  */
  77
  78 int
  79 drm_gem_init(struct drm_device *dev)
  80 {
  81         struct drm_gem_mm *mm;
  82
  83         spin_lock_init(&dev->object_name_lock);
  84         idr_init(&dev->object_name_idr);
  85         atomic_set(&dev->object_count, 0);
  86         atomic_set(&dev->object_memory, 0);
  87         atomic_set(&dev->pin_count, 0);
  88         atomic_set(&dev->pin_memory, 0);
  89         atomic_set(&dev->gtt_count, 0);
  90         atomic_set(&dev->gtt_memory, 0);
  91
  92         mm = kzalloc(sizeof(struct drm_gem_mm), GFP_KERNEL);
  93         if (!mm) {
  94                 DRM_ERROR("out of memory\n");
  95                 return -ENOMEM;
  96         }
  97
  98         dev->mm_private = mm;
  99
 100         if (drm_ht_create(&mm->offset_hash, 19)) {
 101                 kfree(mm);
 102                 return -ENOMEM;
 103         }
 104
 105         if (drm_mm_init(&mm->offset_manager, DRM_FILE_PAGE_OFFSET_START,
 106                         DRM_FILE_PAGE_OFFSET_SIZE)) {
 107                 drm_ht_remove(&mm->offset_hash);
 108                 kfree(mm);
 109                 return -ENOMEM;
 110         }
 111
 112         return 0;
 113 }
 114
 115 void
 116 drm_gem_destroy(struct drm_device *dev)
 117 {
 118         struct drm_gem_mm *mm = dev->mm_private;
 119
 120         drm_mm_takedown(&mm->offset_manager);
 121         drm_ht_remove(&mm->offset_hash);
 122         kfree(mm);
 123         dev->mm_private = NULL;
 124 }
 125
 126 /**
 127  * Allocate a GEM object of the specified size with shmfs backing store
 128  */
 129 struct drm_gem_object *
 130 drm_gem_object_alloc(struct drm_device *dev, size_t size)
 131 {
 132         struct drm_gem_object *obj;
 133
 134         BUG_ON((size & (PAGE_SIZE - 1)) != 0);
 135
 136         obj = kzalloc(sizeof(*obj), GFP_KERNEL);
 137         if (!obj)
 138                 goto free;
 139
 140         obj->dev = dev;
 141         obj->filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
 142         if (IS_ERR(obj->filp))
 143                 goto free;
 144
 145         kref_init(&obj->refcount);
 146         kref_init(&obj->handlecount);
 147         obj->size = size;
 148         if (dev->driver->gem_init_object != NULL &&
 149             dev->driver->gem_init_object(obj) != 0) {
 150                 goto fput;
 151         }
 152         atomic_inc(&dev->object_count);
 153         atomic_add(obj->size, &dev->object_memory);
 154         return obj;
 155 fput:
 156         fput(obj->filp);
 157 free:
 158         kfree(obj);
 159         return NULL;
 160 }
 161 EXPORT_SYMBOL(drm_gem_object_alloc);
 162
 163 /**
 164  * Removes the mapping from handle to filp for this object.
 165  */
 166 static int
 167 drm_gem_handle_delete(struct drm_file *filp, u32 handle)
 168 {
 169         struct drm_device *dev;
 170         struct drm_gem_object *obj;
 171
 172         /* This is gross. The idr system doesn't let us try a delete and
 173          * return an error code.  It just spews if you fail at deleting.
 174          * So, we have to grab a lock around finding the object and then
 175          * doing the delete on it and dropping the refcount, or the user
 176          * could race us to double-decrement the refcount and cause a
 177          * use-after-free later.  Given the frequency of our handle lookups,
 178          * we may want to use ida for number allocation and a hash table
 179          * for the pointers, anyway.
 180          */
 181         spin_lock(&filp->table_lock);
 182
 183         /* Check if we currently have a reference on the object */
 184         obj = idr_find(&filp->object_idr, handle);
 185         if (obj == NULL) {
 186                 spin_unlock(&filp->table_lock);
 187                 return -EINVAL;
 188         }
 189         dev = obj->dev;
 190
 191         /* Release reference and decrement refcount. */
 192         idr_remove(&filp->object_idr, handle);
 193         spin_unlock(&filp->table_lock);
 194
 195         drm_gem_object_handle_unreference_unlocked(obj);
 196
 197         return 0;
 198 }
 199
 200 /**
 201  * Create a handle for this object. This adds a handle reference
 202  * to the object, which includes a regular reference count. Callers
 203  * will likely want to dereference the object afterwards.
 204  */
 205 int
 206 drm_gem_handle_create(struct drm_file *file_priv,
 207                        struct drm_gem_object *obj,
 208                        u32 *handlep)
 209 {
 210         int     ret;
 211
 212         /*
 213          * Get the user-visible handle using idr.
 214          */
 215 again:
 216         /* ensure there is space available to allocate a handle */
 217         if (idr_pre_get(&file_priv->object_idr, GFP_KERNEL) == 0)
 218                 return -ENOMEM;
 219
 220         /* do the allocation under our spinlock */
 221         spin_lock(&file_priv->table_lock);
 222         ret = idr_get_new_above(&file_priv->object_idr, obj, 1, (int *)handlep);
 223         spin_unlock(&file_priv->table_lock);
 224         if (ret == -EAGAIN)
 225                 goto again;
 226
 227         if (ret != 0)
 228                 return ret;
 229
 230         drm_gem_object_handle_reference(obj);
 231         return 0;
 232 }
 233 EXPORT_SYMBOL(drm_gem_handle_create);
 234
 235 /** Returns a reference to the object named by the handle. */
 236 struct drm_gem_object *
 237 drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,
 238                       u32 handle)
 239 {
 240         struct drm_gem_object *obj;
 241
 242         spin_lock(&filp->table_lock);
 243
 244         /* Check if we currently have a reference on the object */
 245         obj = idr_find(&filp->object_idr, handle);
 246         if (obj == NULL) {
 247                 spin_unlock(&filp->table_lock);
 248                 return NULL;
 249         }
 250
 251         drm_gem_object_reference(obj);
 252
 253         spin_unlock(&filp->table_lock);
 254
 255         return obj;
 256 }
 257 EXPORT_SYMBOL(drm_gem_object_lookup);
 258
 259 /**
 260  * Releases the handle to an mm object.
 261  */
 262 int
 263 drm_gem_close_ioctl(struct drm_device *dev, void *data,
 264                     struct drm_file *file_priv)
 265 {
 266         struct drm_gem_close *args = data;
 267         int ret;
 268
 269         if (!(dev->driver->driver_features & DRIVER_GEM))
 270                 return -ENODEV;
 271
 272         ret = drm_gem_handle_delete(file_priv, args->handle);
 273
 274         return ret;
 275 }
 276
 277 /**
 278  * Create a global name for an object, returning the name.
 279  *
 280  * Note that the name does not hold a reference; when the object
 281  * is freed, the name goes away.
 282  */
 283 int
 284 drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 285                     struct drm_file *file_priv)
 286 {
 287         struct drm_gem_flink *args = data;
 288         struct drm_gem_object *obj;
 289         int ret;
 290
 291         if (!(dev->driver->driver_features & DRIVER_GEM))
 292                 return -ENODEV;
 293
 294         obj = drm_gem_object_lookup(dev, file_priv, args->handle);
 295         if (obj == NULL)
 296                 return -EBADF;
 297
 298 again:
 299         if (idr_pre_get(&dev->object_name_idr, GFP_KERNEL) == 0) {
 300                 ret = -ENOMEM;
 301                 goto err;
 302         }
 303
 304         spin_lock(&dev->object_name_lock);
 305         if (!obj->name) {
 306                 ret = idr_get_new_above(&dev->object_name_idr, obj, 1,
 307                                         &obj->name);
 308                 args->name = (uint64_t) obj->name;
 309                 spin_unlock(&dev->object_name_lock);
 310
 311                 if (ret == -EAGAIN)
 312                         goto again;
 313
 314                 if (ret != 0)
 315                         goto err;
 316
 317                 /* Allocate a reference for the name table.  */
 318                 drm_gem_object_reference(obj);
 319         } else {
 320                 args->name = (uint64_t) obj->name;
 321                 spin_unlock(&dev->object_name_lock);
 322                 ret = 0;
 323         }
 324
 325 err:
 326         drm_gem_object_unreference_unlocked(obj);
 327         return ret;
 328 }
 329
 330 /**
 331  * Open an object using the global name, returning a handle and the size.
 332  *
 333  * This handle (of course) holds a reference to the object, so the object
 334  * will not go away until the handle is deleted.
 335  */
 336 int
 337 drm_gem_open_ioctl(struct drm_device *dev, void *data,
 338                    struct drm_file *file_priv)
 339 {
 340         struct drm_gem_open *args = data;
 341         struct drm_gem_object *obj;
 342         int ret;
 343         u32 handle;
 344
 345         if (!(dev->driver->driver_features & DRIVER_GEM))
 346                 return -ENODEV;
 347
 348         spin_lock(&dev->object_name_lock);
 349         obj = idr_find(&dev->object_name_idr, (int) args->name);
 350         if (obj)
 351                 drm_gem_object_reference(obj);
 352         spin_unlock(&dev->object_name_lock);
 353         if (!obj)
 354                 return -ENOENT;
 355
 356         ret = drm_gem_handle_create(file_priv, obj, &handle);
 357         drm_gem_object_unreference_unlocked(obj);
 358         if (ret)
 359                 return ret;
 360
 361         args->handle = handle;
 362         args->size = obj->size;
 363
 364         return 0;
 365 }
 366
 367 /**
 368  * Called at device open time, sets up the structure for handling refcounting
 369  * of mm objects.
 370  */
 371 void
 372 drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
 373 {
 374         idr_init(&file_private->object_idr);
 375         spin_lock_init(&file_private->table_lock);
 376 }
 377
 378 /**
 379  * Called at device close to release the file's
 380  * handle references on objects.
 381  */
 382 static int
 383 drm_gem_object_release_handle(int id, void *ptr, void *data)
 384 {
 385         struct drm_gem_object *obj = ptr;
 386
 387         drm_gem_object_handle_unreference_unlocked(obj);
 388
 389         return 0;
 390 }
 391
 392 /**
 393  * Called at close time when the filp is going away.
 394  *
 395  * Releases any remaining references on objects by this filp.
 396  */
 397 void
 398 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 399 {
 400         idr_for_each(&file_private->object_idr,
 401                      &drm_gem_object_release_handle, NULL);
 402
 403         idr_destroy(&file_private->object_idr);
 404 }
 405
 406 static void
 407 drm_gem_object_free_common(struct drm_gem_object *obj)
 408 {
 409         struct drm_device *dev = obj->dev;
 410         fput(obj->filp);
 411         atomic_dec(&dev->object_count);
 412         atomic_sub(obj->size, &dev->object_memory);
 413         kfree(obj);
 414 }
 415
 416 /**
 417  * Called after the last reference to the object has been lost.
 418  * Must be called holding struct_ mutex
 419  *
 420  * Frees the object
 421  */
 422 void
 423 drm_gem_object_free(struct kref *kref)
 424 {
 425         struct drm_gem_object *obj = (struct drm_gem_object *) kref;
 426         struct drm_device *dev = obj->dev;
 427
 428         BUG_ON(!mutex_is_locked(&dev->struct_mutex));
 429
 430         if (dev->driver->gem_free_object != NULL)
 431                 dev->driver->gem_free_object(obj);
 432
 433         drm_gem_object_free_common(obj);
 434 }
 435 EXPORT_SYMBOL(drm_gem_object_free);
 436
 437 /**
 438  * Called after the last reference to the object has been lost.
 439  * Must be called without holding struct_mutex
 440  *
 441  * Frees the object
 442  */
 443 void
 444 drm_gem_object_free_unlocked(struct kref *kref)
 445 {
 446         struct drm_gem_object *obj = (struct drm_gem_object *) kref;
 447         struct drm_device *dev = obj->dev;
 448
 449         if (dev->driver->gem_free_object_unlocked != NULL)
 450                 dev->driver->gem_free_object_unlocked(obj);
 451         else if (dev->driver->gem_free_object != NULL) {
 452                 mutex_lock(&dev->struct_mutex);
 453                 dev->driver->gem_free_object(obj);
 454                 mutex_unlock(&dev->struct_mutex);
 455         }
 456
 457         drm_gem_object_free_common(obj);
 458 }
 459 EXPORT_SYMBOL(drm_gem_object_free_unlocked);
 460
 461 static void drm_gem_object_ref_bug(struct kref *list_kref)
 462 {
 463         BUG();
 464 }
 465
 466 /**
 467  * Called after the last handle to the object has been closed
 468  *
 469  * Removes any name for the object. Note that this must be
 470  * called before drm_gem_object_free or we'll be touching
 471  * freed memory
 472  */
 473 void
 474 drm_gem_object_handle_free(struct kref *kref)
 475 {
 476         struct drm_gem_object *obj = container_of(kref,
 477                                                   struct drm_gem_object,
 478                                                   handlecount);
 479         struct drm_device *dev = obj->dev;
 480
 481         /* Remove any name for this object */
 482         spin_lock(&dev->object_name_lock);
 483         if (obj->name) {
 484                 idr_remove(&dev->object_name_idr, obj->name);
 485                 obj->name = 0;
 486                 spin_unlock(&dev->object_name_lock);
 487                 /*
 488                  * The object name held a reference to this object, drop
 489                  * that now.
 490                 *
 491                 * This cannot be the last reference, since the handle holds one too.
 492                  */
 493                 kref_put(&obj->refcount, drm_gem_object_ref_bug);
 494         } else
 495                 spin_unlock(&dev->object_name_lock);
 496
 497 }
 498 EXPORT_SYMBOL(drm_gem_object_handle_free);
 499
 500 void drm_gem_vm_open(struct vm_area_struct *vma)
 501 {
 502         struct drm_gem_object *obj = vma->vm_private_data;
 503
 504         drm_gem_object_reference(obj);
 505 }
 506 EXPORT_SYMBOL(drm_gem_vm_open);
 507
 508 void drm_gem_vm_close(struct vm_area_struct *vma)
 509 {
 510         struct drm_gem_object *obj = vma->vm_private_data;
 511
 512         drm_gem_object_unreference_unlocked(obj);
 513 }
 514 EXPORT_SYMBOL(drm_gem_vm_close);
 515
 516
 517 /**
 518  * drm_gem_mmap - memory map routine for GEM objects
 519  * @filp: DRM file pointer
 520  * @vma: VMA for the area to be mapped
 521  *
 522  * If a driver supports GEM object mapping, mmap calls on the DRM file
 523  * descriptor will end up here.
 524  *
 525  * If we find the object based on the offset passed in (vma->vm_pgoff will
 526  * contain the fake offset we created when the GTT map ioctl was called on
 527  * the object), we set up the driver fault handler so that any accesses
 528  * to the object can be trapped, to perform migration, GTT binding, surface
 529  * register allocation, or performance monitoring.
 530  */
 531 int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 532 {
 533         struct drm_file *priv = filp->private_data;
 534         struct drm_device *dev = priv->minor->dev;
 535         struct drm_gem_mm *mm = dev->mm_private;
 536         struct drm_local_map *map = NULL;
 537         struct drm_gem_object *obj;
 538         struct drm_hash_item *hash;
 539         int ret = 0;
 540
 541         mutex_lock(&dev->struct_mutex);
 542
 543         if (drm_ht_find_item(&mm->offset_hash, vma->vm_pgoff, &hash)) {
 544                 mutex_unlock(&dev->struct_mutex);
 545                 return drm_mmap(filp, vma);
 546         }
 547
 548         map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
 549         if (!map ||
 550             ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) {
 551                 ret =  -EPERM;
 552                 goto out_unlock;
 553         }
 554
 555         /* Check for valid size. */
 556         if (map->size < vma->vm_end - vma->vm_start) {
 557                 ret = -EINVAL;
 558                 goto out_unlock;
 559         }
 560
 561         obj = map->handle;
 562         if (!obj->dev->driver->gem_vm_ops) {
 563                 ret = -EINVAL;
 564                 goto out_unlock;
 565         }
 566
 567         vma->vm_flags |= VM_RESERVED | VM_IO | VM_PFNMAP | VM_DONTEXPAND;
 568         vma->vm_ops = obj->dev->driver->gem_vm_ops;
 569         vma->vm_private_data = map->handle;
 570         vma->vm_page_prot =  pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
 571
 572         /* Take a ref for this mapping of the object, so that the fault
 573          * handler can dereference the mmap offset's pointer to the object.
 574          * This reference is cleaned up by the corresponding vm_close
 575          * (which should happen whether the vma was created by this call, or
 576          * by a vm_open due to mremap or partial unmap or whatever).
 577          */
 578         drm_gem_object_reference(obj);
 579
 580         vma->vm_file = filp;    /* Needed for drm_vm_open() */
 581         drm_vm_open_locked(vma);
 582
 583 out_unlock:
 584         mutex_unlock(&dev->struct_mutex);
 585
 586         return ret;
 587 }
 588 EXPORT_SYMBOL(drm_gem_mmap);