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 = drm_calloc(1, sizeof(struct drm_gem_mm), DRM_MEM_MM);
  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                 drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_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_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_MM);
 108                 drm_ht_remove(&mm->offset_hash);
 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         drm_free(mm, sizeof(struct drm_gem_mm), DRM_MEM_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 = kcalloc(1, sizeof(*obj), GFP_KERNEL);
 137
 138         obj->dev = dev;
 139         obj->filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
 140         if (IS_ERR(obj->filp)) {
 141                 kfree(obj);
 142                 return NULL;
 143         }
 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                 fput(obj->filp);
 151                 kfree(obj);
 152                 return NULL;
 153         }
 154         atomic_inc(&dev->object_count);
 155         atomic_add(obj->size, &dev->object_memory);
 156         return obj;
 157 }
 158 EXPORT_SYMBOL(drm_gem_object_alloc);
 159
 160 /**
 161  * Removes the mapping from handle to filp for this object.
 162  */
 163 static int
 164 drm_gem_handle_delete(struct drm_file *filp, int handle)
 165 {
 166         struct drm_device *dev;
 167         struct drm_gem_object *obj;
 168
 169         /* This is gross. The idr system doesn't let us try a delete and
 170          * return an error code.  It just spews if you fail at deleting.
 171          * So, we have to grab a lock around finding the object and then
 172          * doing the delete on it and dropping the refcount, or the user
 173          * could race us to double-decrement the refcount and cause a
 174          * use-after-free later.  Given the frequency of our handle lookups,
 175          * we may want to use ida for number allocation and a hash table
 176          * for the pointers, anyway.
 177          */
 178         spin_lock(&filp->table_lock);
 179
 180         /* Check if we currently have a reference on the object */
 181         obj = idr_find(&filp->object_idr, handle);
 182         if (obj == NULL) {
 183                 spin_unlock(&filp->table_lock);
 184                 return -EINVAL;
 185         }
 186         dev = obj->dev;
 187
 188         /* Release reference and decrement refcount. */
 189         idr_remove(&filp->object_idr, handle);
 190         spin_unlock(&filp->table_lock);
 191
 192         mutex_lock(&dev->struct_mutex);
 193         drm_gem_object_handle_unreference(obj);
 194         mutex_unlock(&dev->struct_mutex);
 195
 196         return 0;
 197 }
 198
 199 /**
 200  * Create a handle for this object. This adds a handle reference
 201  * to the object, which includes a regular reference count. Callers
 202  * will likely want to dereference the object afterwards.
 203  */
 204 int
 205 drm_gem_handle_create(struct drm_file *file_priv,
 206                        struct drm_gem_object *obj,
 207                        int *handlep)
 208 {
 209         int     ret;
 210
 211         /*
 212          * Get the user-visible handle using idr.
 213          */
 214 again:
 215         /* ensure there is space available to allocate a handle */
 216         if (idr_pre_get(&file_priv->object_idr, GFP_KERNEL) == 0)
 217                 return -ENOMEM;
 218
 219         /* do the allocation under our spinlock */
 220         spin_lock(&file_priv->table_lock);
 221         ret = idr_get_new_above(&file_priv->object_idr, obj, 1, handlep);
 222         spin_unlock(&file_priv->table_lock);
 223         if (ret == -EAGAIN)
 224                 goto again;
 225
 226         if (ret != 0)
 227                 return ret;
 228
 229         drm_gem_object_handle_reference(obj);
 230         return 0;
 231 }
 232 EXPORT_SYMBOL(drm_gem_handle_create);
 233
 234 /** Returns a reference to the object named by the handle. */
 235 struct drm_gem_object *
 236 drm_gem_object_lookup(struct drm_device *dev, struct drm_file *filp,
 237                       int handle)
 238 {
 239         struct drm_gem_object *obj;
 240
 241         spin_lock(&filp->table_lock);
 242
 243         /* Check if we currently have a reference on the object */
 244         obj = idr_find(&filp->object_idr, handle);
 245         if (obj == NULL) {
 246                 spin_unlock(&filp->table_lock);
 247                 return NULL;
 248         }
 249
 250         drm_gem_object_reference(obj);
 251
 252         spin_unlock(&filp->table_lock);
 253
 254         return obj;
 255 }
 256 EXPORT_SYMBOL(drm_gem_object_lookup);
 257
 258 /**
 259  * Releases the handle to an mm object.
 260  */
 261 int
 262 drm_gem_close_ioctl(struct drm_device *dev, void *data,
 263                     struct drm_file *file_priv)
 264 {
 265         struct drm_gem_close *args = data;
 266         int ret;
 267
 268         if (!(dev->driver->driver_features & DRIVER_GEM))
 269                 return -ENODEV;
 270
 271         ret = drm_gem_handle_delete(file_priv, args->handle);
 272
 273         return ret;
 274 }
 275
 276 /**
 277  * Create a global name for an object, returning the name.
 278  *
 279  * Note that the name does not hold a reference; when the object
 280  * is freed, the name goes away.
 281  */
 282 int
 283 drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 284                     struct drm_file *file_priv)
 285 {
 286         struct drm_gem_flink *args = data;
 287         struct drm_gem_object *obj;
 288         int ret;
 289
 290         if (!(dev->driver->driver_features & DRIVER_GEM))
 291                 return -ENODEV;
 292
 293         obj = drm_gem_object_lookup(dev, file_priv, args->handle);
 294         if (obj == NULL)
 295                 return -EBADF;
 296
 297 again:
 298         if (idr_pre_get(&dev->object_name_idr, GFP_KERNEL) == 0)
 299                 return -ENOMEM;
 300
 301         spin_lock(&dev->object_name_lock);
 302         if (obj->name) {
 303                 args->name = obj->name;
 304                 spin_unlock(&dev->object_name_lock);
 305                 return 0;
 306         }
 307         ret = idr_get_new_above(&dev->object_name_idr, obj, 1,
 308                                  &obj->name);
 309         spin_unlock(&dev->object_name_lock);
 310         if (ret == -EAGAIN)
 311                 goto again;
 312
 313         if (ret != 0) {
 314                 mutex_lock(&dev->struct_mutex);
 315                 drm_gem_object_unreference(obj);
 316                 mutex_unlock(&dev->struct_mutex);
 317                 return ret;
 318         }
 319
 320         /*
 321          * Leave the reference from the lookup around as the
 322          * name table now holds one
 323          */
 324         args->name = (uint64_t) obj->name;
 325
 326         return 0;
 327 }
 328
 329 /**
 330  * Open an object using the global name, returning a handle and the size.
 331  *
 332  * This handle (of course) holds a reference to the object, so the object
 333  * will not go away until the handle is deleted.
 334  */
 335 int
 336 drm_gem_open_ioctl(struct drm_device *dev, void *data,
 337                    struct drm_file *file_priv)
 338 {
 339         struct drm_gem_open *args = data;
 340         struct drm_gem_object *obj;
 341         int ret;
 342         int handle;
 343
 344         if (!(dev->driver->driver_features & DRIVER_GEM))
 345                 return -ENODEV;
 346
 347         spin_lock(&dev->object_name_lock);
 348         obj = idr_find(&dev->object_name_idr, (int) args->name);
 349         if (obj)
 350                 drm_gem_object_reference(obj);
 351         spin_unlock(&dev->object_name_lock);
 352         if (!obj)
 353                 return -ENOENT;
 354
 355         ret = drm_gem_handle_create(file_priv, obj, &handle);
 356         mutex_lock(&dev->struct_mutex);
 357         drm_gem_object_unreference(obj);
 358         mutex_unlock(&dev->struct_mutex);
 359         if (ret)
 360                 return ret;
 361
 362         args->handle = handle;
 363         args->size = obj->size;
 364
 365         return 0;
 366 }
 367
 368 /**
 369  * Called at device open time, sets up the structure for handling refcounting
 370  * of mm objects.
 371  */
 372 void
 373 drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
 374 {
 375         idr_init(&file_private->object_idr);
 376         spin_lock_init(&file_private->table_lock);
 377 }
 378
 379 /**
 380  * Called at device close to release the file's
 381  * handle references on objects.
 382  */
 383 static int
 384 drm_gem_object_release_handle(int id, void *ptr, void *data)
 385 {
 386         struct drm_gem_object *obj = ptr;
 387
 388         drm_gem_object_handle_unreference(obj);
 389
 390         return 0;
 391 }
 392
 393 /**
 394  * Called at close time when the filp is going away.
 395  *
 396  * Releases any remaining references on objects by this filp.
 397  */
 398 void
 399 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 400 {
 401         mutex_lock(&dev->struct_mutex);
 402         idr_for_each(&file_private->object_idr,
 403                      &drm_gem_object_release_handle, NULL);
 404
 405         idr_destroy(&file_private->object_idr);
 406         mutex_unlock(&dev->struct_mutex);
 407 }
 408
 409 /**
 410  * Called after the last reference to the object has been lost.
 411  *
 412  * Frees the object
 413  */
 414 void
 415 drm_gem_object_free(struct kref *kref)
 416 {
 417         struct drm_gem_object *obj = (struct drm_gem_object *) kref;
 418         struct drm_device *dev = obj->dev;
 419
 420         BUG_ON(!mutex_is_locked(&dev->struct_mutex));
 421
 422         if (dev->driver->gem_free_object != NULL)
 423                 dev->driver->gem_free_object(obj);
 424
 425         fput(obj->filp);
 426         atomic_dec(&dev->object_count);
 427         atomic_sub(obj->size, &dev->object_memory);
 428         kfree(obj);
 429 }
 430 EXPORT_SYMBOL(drm_gem_object_free);
 431
 432 /**
 433  * Called after the last handle to the object has been closed
 434  *
 435  * Removes any name for the object. Note that this must be
 436  * called before drm_gem_object_free or we'll be touching
 437  * freed memory
 438  */
 439 void
 440 drm_gem_object_handle_free(struct kref *kref)
 441 {
 442         struct drm_gem_object *obj = container_of(kref,
 443                                                   struct drm_gem_object,
 444                                                   handlecount);
 445         struct drm_device *dev = obj->dev;
 446
 447         /* Remove any name for this object */
 448         spin_lock(&dev->object_name_lock);
 449         if (obj->name) {
 450                 idr_remove(&dev->object_name_idr, obj->name);
 451                 spin_unlock(&dev->object_name_lock);
 452                 /*
 453                  * The object name held a reference to this object, drop
 454                  * that now.
 455                  */
 456                 drm_gem_object_unreference(obj);
 457         } else
 458                 spin_unlock(&dev->object_name_lock);
 459
 460 }
 461 EXPORT_SYMBOL(drm_gem_object_handle_free);
 462
 463 /**
 464  * drm_gem_mmap - memory map routine for GEM objects
 465  * @filp: DRM file pointer
 466  * @vma: VMA for the area to be mapped
 467  *
 468  * If a driver supports GEM object mapping, mmap calls on the DRM file
 469  * descriptor will end up here.
 470  *
 471  * If we find the object based on the offset passed in (vma->vm_pgoff will
 472  * contain the fake offset we created when the GTT map ioctl was called on
 473  * the object), we set up the driver fault handler so that any accesses
 474  * to the object can be trapped, to perform migration, GTT binding, surface
 475  * register allocation, or performance monitoring.
 476  */
 477 int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
 478 {
 479         struct drm_file *priv = filp->private_data;
 480         struct drm_device *dev = priv->minor->dev;
 481         struct drm_gem_mm *mm = dev->mm_private;
 482         struct drm_map *map = NULL;
 483         struct drm_gem_object *obj;
 484         struct drm_hash_item *hash;
 485         unsigned long prot;
 486         int ret = 0;
 487
 488         mutex_lock(&dev->struct_mutex);
 489
 490         if (drm_ht_find_item(&mm->offset_hash, vma->vm_pgoff, &hash)) {
 491                 mutex_unlock(&dev->struct_mutex);
 492                 return drm_mmap(filp, vma);
 493         }
 494
 495         map = drm_hash_entry(hash, struct drm_map_list, hash)->map;
 496         if (!map ||
 497             ((map->flags & _DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN))) {
 498                 ret =  -EPERM;
 499                 goto out_unlock;
 500         }
 501
 502         /* Check for valid size. */
 503         if (map->size < vma->vm_end - vma->vm_start) {
 504                 ret = -EINVAL;
 505                 goto out_unlock;
 506         }
 507
 508         obj = map->handle;
 509         if (!obj->dev->driver->gem_vm_ops) {
 510                 ret = -EINVAL;
 511                 goto out_unlock;
 512         }
 513
 514         vma->vm_flags |= VM_RESERVED | VM_IO | VM_PFNMAP | VM_DONTEXPAND;
 515         vma->vm_ops = obj->dev->driver->gem_vm_ops;
 516         vma->vm_private_data = map->handle;
 517         /* FIXME: use pgprot_writecombine when available */
 518         prot = pgprot_val(vma->vm_page_prot);
 519 #ifdef CONFIG_X86
 520         prot |= _PAGE_CACHE_WC;
 521 #endif
 522         vma->vm_page_prot = __pgprot(prot);
 523
 524         vma->vm_file = filp;    /* Needed for drm_vm_open() */
 525         drm_vm_open_locked(vma);
 526
 527 out_unlock:
 528         mutex_unlock(&dev->struct_mutex);
 529
 530         return ret;
 531 }
 532 EXPORT_SYMBOL(drm_gem_mmap);