2 * Copyright © 2008 Intel Corporation
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:
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
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
24 * Eric Anholt <eric@anholt.net>
28 * Copyright (c) 2011 The FreeBSD Foundation
29 * All rights reserved.
31 * This software was developed by Konstantin Belousov under sponsorship from
32 * the FreeBSD Foundation.
34 * Redistribution and use in source and binary forms, with or without
35 * modification, are permitted provided that the following conditions
37 * 1. Redistributions of source code must retain the above copyright
38 * notice, this list of conditions and the following disclaimer.
39 * 2. Redistributions in binary form must reproduce the above copyright
40 * notice, this list of conditions and the following disclaimer in the
41 * documentation and/or other materials provided with the distribution.
43 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
44 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
45 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
46 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
47 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
48 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
49 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
50 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
51 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
52 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58 #include <sys/param.h>
59 #include <sys/systm.h>
60 #include <sys/limits.h>
62 #include <sys/mutex.h>
66 #include <vm/vm_page.h>
68 #include <linux/types.h>
70 #include <linux/module.h>
72 #include <drm/drm_vma_manager.h>
73 #include <drm/drm_gem.h>
74 #include "drm_internal.h"
78 * This file provides some of the base ioctls and library routines for
79 * the graphics memory manager implemented by each device driver.
81 * Because various devices have different requirements in terms of
82 * synchronization and migration strategies, implementing that is left up to
83 * the driver, and all that the general API provides should be generic --
84 * allocating objects, reading/writing data with the cpu, freeing objects.
85 * Even there, platform-dependent optimizations for reading/writing data with
86 * the CPU mean we'll likely hook those out to driver-specific calls. However,
87 * the DRI2 implementation wants to have at least allocate/mmap be generic.
89 * The goal was to have swap-backed object allocation managed through
90 * struct file. However, file descriptors as handles to a struct file have
92 * - Process limits prevent more than 1024 or so being used at a time by
94 * - Inability to allocate high fds will aggravate the X Server's select()
95 * handling, and likely that of many GL client applications as well.
97 * This led to a plan of using our own integer IDs (called handles, following
98 * DRM terminology) to mimic fds, and implement the fd syscalls we need as
99 * ioctls. The objects themselves will still include the struct file so
100 * that we can transition to fds if the required kernel infrastructure shows
101 * up at a later date, and as our interface with shmfs for memory allocation.
105 * We make up offsets for buffer objects so we can recognize them at
109 /* pgoff in mmap is an unsigned long, so we need to make sure that
110 * the faked up offset will fit
113 #if BITS_PER_LONG == 64
114 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFFUL >> PAGE_SHIFT) + 1)
115 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFFUL >> PAGE_SHIFT) * 16)
117 #define DRM_FILE_PAGE_OFFSET_START ((0xFFFFFFFUL >> PAGE_SHIFT) + 1)
118 #define DRM_FILE_PAGE_OFFSET_SIZE ((0xFFFFFFFUL >> PAGE_SHIFT) * 16)
122 * drm_gem_init - Initialize the GEM device fields
123 * @dev: drm_devic structure to initialize
126 drm_gem_init(struct drm_device *dev)
128 struct drm_gem_mm *mm;
130 lockinit(&dev->object_name_lock, "objnam", 0, LK_CANRECURSE);
131 idr_init(&dev->object_name_idr);
133 mm = kzalloc(sizeof(struct drm_gem_mm), GFP_KERNEL);
135 DRM_ERROR("out of memory\n");
139 dev->mm_private = mm;
141 if (drm_ht_create(&mm->offset_hash, 12)) {
146 mm->idxunr = new_unrhdr(0, DRM_GEM_MAX_IDX, NULL);
147 drm_mm_init(&mm->offset_manager, DRM_FILE_PAGE_OFFSET_START,
148 DRM_FILE_PAGE_OFFSET_SIZE);
149 drm_vma_offset_manager_init(&mm->vma_manager,
150 DRM_FILE_PAGE_OFFSET_START,
151 DRM_FILE_PAGE_OFFSET_SIZE);
157 drm_gem_destroy(struct drm_device *dev)
159 struct drm_gem_mm *mm = dev->mm_private;
161 drm_mm_takedown(&mm->offset_manager);
162 drm_ht_remove(&mm->offset_hash);
164 drm_vma_offset_manager_destroy(&mm->vma_manager);
165 delete_unrhdr(mm->idxunr);
167 dev->mm_private = NULL;
171 * Initialize an already allocated GEM object of the specified size with
172 * shmfs backing store.
174 int drm_gem_object_init(struct drm_device *dev,
175 struct drm_gem_object *obj, size_t size)
177 drm_gem_private_object_init(dev, obj, size);
179 obj->filp = default_pager_alloc(NULL, size,
180 VM_PROT_READ | VM_PROT_WRITE, 0);
184 EXPORT_SYMBOL(drm_gem_object_init);
187 * drm_gem_object_init - initialize an allocated private GEM object
188 * @dev: drm_device the object should be initialized for
189 * @obj: drm_gem_object to initialize
192 * Initialize an already allocated GEM object of the specified size with
193 * no GEM provided backing store. Instead the caller is responsible for
194 * backing the object and handling it.
196 void drm_gem_private_object_init(struct drm_device *dev,
197 struct drm_gem_object *obj, size_t size)
199 BUG_ON((size & (PAGE_SIZE - 1)) != 0);
204 kref_init(&obj->refcount);
205 obj->handle_count = 0;
207 drm_vma_node_reset(&obj->vma_node);
209 EXPORT_SYMBOL(drm_gem_private_object_init);
212 drm_gem_remove_prime_handles(struct drm_gem_object *obj, struct drm_file *filp)
215 * Note: obj->dma_buf can't disappear as long as we still hold a
216 * handle reference in obj->handle_count.
218 mutex_lock(&filp->prime.lock);
221 drm_prime_remove_buf_handle_locked(&filp->prime,
225 mutex_unlock(&filp->prime.lock);
228 static void drm_gem_object_ref_bug(struct kref *list_kref)
234 * drm_gem_object_handle_free - release resources bound to userspace handles
235 * @obj: GEM object to clean up.
237 * Called after the last handle to the object has been closed
239 * Removes any name for the object. Note that this must be
240 * called before drm_gem_object_free or we'll be touching
243 static void drm_gem_object_handle_free(struct drm_gem_object *obj)
245 struct drm_device *dev = obj->dev;
247 /* Remove any name for this object */
249 idr_remove(&dev->object_name_idr, obj->name);
252 * The object name held a reference to this object, drop
255 * This cannot be the last reference, since the handle holds one too.
257 kref_put(&obj->refcount, drm_gem_object_ref_bug);
261 static void drm_gem_object_exported_dma_buf_free(struct drm_gem_object *obj)
264 /* Unbreak the reference cycle if we have an exported dma_buf. */
266 dma_buf_put(obj->dma_buf);
273 drm_gem_object_handle_unreference_unlocked(struct drm_gem_object *obj)
275 struct drm_device *dev = obj->dev;
277 if (WARN_ON(obj->handle_count == 0))
281 * Must bump handle count first as this may be the last
282 * ref, in which case the object would disappear before we
286 mutex_lock(&dev->object_name_lock);
287 if (--obj->handle_count == 0) {
288 drm_gem_object_handle_free(obj);
289 drm_gem_object_exported_dma_buf_free(obj);
291 mutex_unlock(&dev->object_name_lock);
293 drm_gem_object_unreference_unlocked(obj);
297 * Called at device or object close to release the file's
298 * handle references on objects.
301 drm_gem_object_release_handle(int id, void *ptr, void *data)
303 struct drm_file *file_priv = data;
304 struct drm_gem_object *obj = ptr;
305 struct drm_device *dev = obj->dev;
307 drm_gem_remove_prime_handles(obj, file_priv);
309 if (dev->driver->gem_close_object)
310 dev->driver->gem_close_object(obj, file_priv);
312 drm_gem_object_handle_unreference_unlocked(obj);
318 * drm_gem_handle_delete - deletes the given file-private handle
319 * @filp: drm file-private structure to use for the handle look up
320 * @handle: userspace handle to delete
322 * Removes the GEM handle from the @filp lookup table which has been added with
323 * drm_gem_handle_create(). If this is the last handle also cleans up linked
324 * resources like GEM names.
327 drm_gem_handle_delete(struct drm_file *filp, u32 handle)
329 struct drm_device *dev;
330 struct drm_gem_object *obj;
332 /* This is gross. The idr system doesn't let us try a delete and
333 * return an error code. It just spews if you fail at deleting.
334 * So, we have to grab a lock around finding the object and then
335 * doing the delete on it and dropping the refcount, or the user
336 * could race us to double-decrement the refcount and cause a
337 * use-after-free later. Given the frequency of our handle lookups,
338 * we may want to use ida for number allocation and a hash table
339 * for the pointers, anyway.
341 lockmgr(&filp->table_lock, LK_EXCLUSIVE);
343 /* Check if we currently have a reference on the object */
344 obj = idr_find(&filp->object_idr, handle);
346 lockmgr(&filp->table_lock, LK_RELEASE);
351 /* Release reference and decrement refcount. */
352 idr_remove(&filp->object_idr, handle);
353 lockmgr(&filp->table_lock, LK_RELEASE);
355 drm_gem_remove_prime_handles(obj, filp);
357 if (dev->driver->gem_close_object)
358 dev->driver->gem_close_object(obj, filp);
359 drm_gem_object_handle_unreference_unlocked(obj);
363 EXPORT_SYMBOL(drm_gem_handle_delete);
366 * drm_gem_dumb_destroy - dumb fb callback helper for gem based drivers
367 * @file: drm file-private structure to remove the dumb handle from
368 * @dev: corresponding drm_device
369 * @handle: the dumb handle to remove
371 * This implements the ->dumb_destroy kms driver callback for drivers which use
372 * gem to manage their backing storage.
374 int drm_gem_dumb_destroy(struct drm_file *file,
375 struct drm_device *dev,
378 return drm_gem_handle_delete(file, handle);
380 EXPORT_SYMBOL(drm_gem_dumb_destroy);
383 * drm_gem_handle_create_tail - internal functions to create a handle
384 * @file_priv: drm file-private structure to register the handle for
385 * @obj: object to register
386 * @handlep: pointer to return the created handle to the caller
388 * This expects the dev->object_name_lock to be held already and will drop it
389 * before returning. Used to avoid races in establishing new handles when
390 * importing an object from either an flink name or a dma-buf.
392 * Handles must be release again through drm_gem_handle_delete(). This is done
393 * when userspace closes @file_priv for all attached handles, or through the
394 * GEM_CLOSE ioctl for individual handles.
397 drm_gem_handle_create_tail(struct drm_file *file_priv,
398 struct drm_gem_object *obj,
401 struct drm_device *dev = obj->dev;
404 *handlep = 0; /* whack gcc warning */
405 WARN_ON(!mutex_is_locked(&dev->object_name_lock));
408 * Get the user-visible handle using idr. Preload and perform
409 * allocation under our spinlock.
411 idr_preload(GFP_KERNEL);
412 lockmgr(&file_priv->table_lock, LK_EXCLUSIVE);
414 ret = idr_alloc(&file_priv->object_idr, obj, 1, 0, GFP_NOWAIT);
415 drm_gem_object_reference(obj);
417 lockmgr(&file_priv->table_lock, LK_RELEASE);
419 mutex_unlock(&dev->object_name_lock);
421 drm_gem_object_handle_unreference_unlocked(obj);
427 ret = drm_vma_node_allow(&obj->vma_node, file_priv->filp);
429 drm_gem_handle_delete(file_priv, *handlep);
434 if (dev->driver->gem_open_object) {
435 ret = dev->driver->gem_open_object(obj, file_priv);
437 drm_gem_handle_delete(file_priv, *handlep);
446 * drm_gem_handle_create - create a gem handle for an object
447 * @file_priv: drm file-private structure to register the handle for
448 * @obj: object to register
449 * @handlep: pionter to return the created handle to the caller
451 * Create a handle for this object. This adds a handle reference
452 * to the object, which includes a regular reference count. Callers
453 * will likely want to dereference the object afterwards.
455 int drm_gem_handle_create(struct drm_file *file_priv,
456 struct drm_gem_object *obj,
459 mutex_lock(&obj->dev->object_name_lock);
461 return drm_gem_handle_create_tail(file_priv, obj, handlep);
463 EXPORT_SYMBOL(drm_gem_handle_create);
466 * drm_gem_free_mmap_offset - release a fake mmap offset for an object
467 * @obj: obj in question
469 * This routine frees fake offsets allocated by drm_gem_create_mmap_offset().
471 * Note that drm_gem_object_release() already calls this function, so drivers
472 * don't have to take care of releasing the mmap offset themselves when freeing
476 drm_gem_free_mmap_offset(struct drm_gem_object *obj)
478 struct drm_device *dev = obj->dev;
479 struct drm_gem_mm *mm = dev->mm_private;
480 struct drm_hash_item *list;
484 list = &obj->map_list;
486 drm_ht_remove_item(&mm->offset_hash, list);
487 free_unr(mm->idxunr, list->key);
490 drm_vma_offset_remove(&mm->vma_manager, &obj->vma_node);
492 EXPORT_SYMBOL(drm_gem_free_mmap_offset);
495 * drm_gem_create_mmap_offset_size - create a fake mmap offset for an object
496 * @obj: obj in question
497 * @size: the virtual size
499 * GEM memory mapping works by handing back to userspace a fake mmap offset
500 * it can use in a subsequent mmap(2) call. The DRM core code then looks
501 * up the object based on the offset and sets up the various memory mapping
504 * This routine allocates and attaches a fake offset for @obj, in cases where
505 * the virtual size differs from the physical size (ie. obj->size). Otherwise
506 * just use drm_gem_create_mmap_offset().
508 * This function is idempotent and handles an already allocated mmap offset
509 * transparently. Drivers do not need to check for this case.
512 drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size)
514 struct drm_device *dev = obj->dev;
515 struct drm_gem_mm *mm = dev->mm_private;
521 obj->map_list.key = alloc_unr(mm->idxunr);
522 ret = drm_ht_insert_item(&mm->offset_hash, &obj->map_list);
524 DRM_ERROR("failed to add to map hash\n");
525 free_unr(mm->idxunr, obj->map_list.key);
531 return drm_vma_offset_add(&mm->vma_manager, &obj->vma_node,
534 EXPORT_SYMBOL(drm_gem_create_mmap_offset_size);
537 * drm_gem_create_mmap_offset - create a fake mmap offset for an object
538 * @obj: obj in question
540 * GEM memory mapping works by handing back to userspace a fake mmap offset
541 * it can use in a subsequent mmap(2) call. The DRM core code then looks
542 * up the object based on the offset and sets up the various memory mapping
545 * This routine allocates and attaches a fake offset for @obj.
547 * Drivers can call drm_gem_free_mmap_offset() before freeing @obj to release
548 * the fake offset again.
550 int drm_gem_create_mmap_offset(struct drm_gem_object *obj)
552 return drm_gem_create_mmap_offset_size(obj, obj->size);
554 EXPORT_SYMBOL(drm_gem_create_mmap_offset);
557 * drm_gem_object_lookup - look up a GEM object from it's handle
558 * @filp: DRM file private date
559 * @handle: userspace handle
563 * A reference to the object named by the handle if such exists on @filp, NULL
566 struct drm_gem_object *
567 drm_gem_object_lookup(struct drm_file *filp, u32 handle)
569 struct drm_gem_object *obj;
571 lockmgr(&filp->table_lock, LK_EXCLUSIVE);
573 /* Check if we currently have a reference on the object */
574 obj = idr_find(&filp->object_idr, handle);
576 drm_gem_object_reference(obj);
578 lockmgr(&filp->table_lock, LK_RELEASE);
582 EXPORT_SYMBOL(drm_gem_object_lookup);
585 * drm_gem_close_ioctl - implementation of the GEM_CLOSE ioctl
588 * @file_priv: drm file-private structure
590 * Releases the handle to an mm object.
593 drm_gem_close_ioctl(struct drm_device *dev, void *data,
594 struct drm_file *file_priv)
596 struct drm_gem_close *args = data;
599 if (!drm_core_check_feature(dev, DRIVER_GEM))
602 ret = drm_gem_handle_delete(file_priv, args->handle);
608 * Create a global name for an object, returning the name.
610 * Note that the name does not hold a reference; when the object
611 * is freed, the name goes away.
614 drm_gem_flink_ioctl(struct drm_device *dev, void *data,
615 struct drm_file *file_priv)
617 struct drm_gem_flink *args = data;
618 struct drm_gem_object *obj;
621 if (!drm_core_check_feature(dev, DRIVER_GEM))
624 obj = drm_gem_object_lookup(file_priv, args->handle);
628 idr_preload(GFP_KERNEL);
629 lockmgr(&dev->object_name_lock, LK_EXCLUSIVE);
630 /* prevent races with concurrent gem_close. */
631 if (obj->handle_count == 0) {
637 ret = idr_alloc(&dev->object_name_idr, obj, 1, 0, GFP_NOWAIT);
643 /* Allocate a reference for the name table. */
644 drm_gem_object_reference(obj);
647 args->name = (uint64_t) obj->name;
651 lockmgr(&dev->object_name_lock, LK_RELEASE);
653 drm_gem_object_unreference_unlocked(obj);
658 * drm_gem_open - implementation of the GEM_OPEN ioctl
661 * @file_priv: drm file-private structure
663 * Open an object using the global name, returning a handle and the size.
665 * This handle (of course) holds a reference to the object, so the object
666 * will not go away until the handle is deleted.
669 drm_gem_open_ioctl(struct drm_device *dev, void *data,
670 struct drm_file *file_priv)
672 struct drm_gem_open *args = data;
673 struct drm_gem_object *obj;
677 if (!drm_core_check_feature(dev, DRIVER_GEM))
680 lockmgr(&dev->object_name_lock, LK_EXCLUSIVE);
681 obj = idr_find(&dev->object_name_idr, (int) args->name);
683 drm_gem_object_reference(obj);
684 lockmgr(&dev->object_name_lock, LK_RELEASE);
688 ret = drm_gem_handle_create(file_priv, obj, &handle);
689 drm_gem_object_unreference_unlocked(obj);
693 args->handle = handle;
694 args->size = obj->size;
700 * gem_gem_open - initalizes GEM file-private structures at devnode open time
701 * @dev: drm_device which is being opened by userspace
702 * @file_private: drm file-private structure to set up
704 * Called at device open time, sets up the structure for handling refcounting
708 drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
710 idr_init(&file_private->object_idr);
711 lockinit(&file_private->table_lock, "fptab", 0, LK_CANRECURSE);
715 * drm_gem_release - release file-private GEM resources
716 * @dev: drm_device which is being closed by userspace
717 * @file_private: drm file-private structure to clean up
719 * Called at close time when the filp is going away.
721 * Releases any remaining references on objects by this filp.
724 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
726 idr_for_each(&file_private->object_idr,
727 &drm_gem_object_release_handle, file_private);
728 idr_destroy(&file_private->object_idr);
732 * drm_gem_object_release - release GEM buffer object resources
733 * @obj: GEM buffer object
735 * This releases any structures and resources used by @obj and is the invers of
736 * drm_gem_object_init().
739 drm_gem_object_release(struct drm_gem_object *obj)
743 * obj->vm_obj can be NULL for private gem objects.
745 vm_object_deallocate(obj->filp);
747 EXPORT_SYMBOL(drm_gem_object_release);
750 * drm_gem_object_free - free a GEM object
751 * @kref: kref of the object to free
753 * Called after the last reference to the object has been lost.
754 * Must be called holding struct_ mutex
759 drm_gem_object_free(struct kref *kref)
761 struct drm_gem_object *obj =
762 container_of(kref, struct drm_gem_object, refcount);
763 struct drm_device *dev = obj->dev;
765 WARN_ON(!mutex_is_locked(&dev->struct_mutex));
767 if (dev->driver->gem_free_object != NULL)
768 dev->driver->gem_free_object(obj);
770 EXPORT_SYMBOL(drm_gem_object_free);
773 * drm_gem_object_unreference_unlocked - release a GEM BO reference
774 * @obj: GEM buffer object
776 * This releases a reference to @obj. Callers must not hold the
777 * dev->struct_mutex lock when calling this function.
779 * See also __drm_gem_object_unreference().
782 drm_gem_object_unreference_unlocked(struct drm_gem_object *obj)
784 struct drm_device *dev;
790 if (kref_put_mutex(&obj->refcount, drm_gem_object_free, &dev->struct_mutex))
791 mutex_unlock(&dev->struct_mutex);
793 might_lock(&dev->struct_mutex);
795 EXPORT_SYMBOL(drm_gem_object_unreference_unlocked);
798 * drm_gem_object_unreference - release a GEM BO reference
799 * @obj: GEM buffer object
801 * This releases a reference to @obj. Callers must hold the dev->struct_mutex
802 * lock when calling this function, even when the driver doesn't use
803 * dev->struct_mutex for anything.
805 * For drivers not encumbered with legacy locking use
806 * drm_gem_object_unreference_unlocked() instead.
809 drm_gem_object_unreference(struct drm_gem_object *obj)
813 WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
816 kref_put(&obj->refcount, drm_gem_object_free);
819 EXPORT_SYMBOL(drm_gem_object_unreference);
821 static struct drm_gem_object *
822 drm_gem_object_from_offset(struct drm_device *dev, vm_ooffset_t offset)
824 struct drm_gem_object *obj;
825 struct drm_gem_mm *mm = dev->mm_private;
826 struct drm_hash_item *hash;
828 if ((offset & DRM_GEM_MAPPING_MASK) != DRM_GEM_MAPPING_KEY)
830 offset &= ~DRM_GEM_MAPPING_KEY;
832 if (drm_ht_find_item(&mm->offset_hash, DRM_GEM_MAPPING_IDX(offset),
836 obj = container_of(hash, struct drm_gem_object, map_list);
841 drm_gem_mmap_single(struct drm_device *dev, vm_ooffset_t *offset, vm_size_t size,
842 struct vm_object **obj_res, int nprot)
844 struct drm_gem_object *gem_obj;
845 struct vm_object *vm_obj;
848 gem_obj = drm_gem_object_from_offset(dev, *offset);
849 if (gem_obj == NULL) {
854 drm_gem_object_reference(gem_obj);
856 vm_obj = cdev_pager_allocate(gem_obj, OBJT_MGTDEVICE,
857 dev->driver->gem_vm_ops, size, nprot,
858 DRM_GEM_MAPPING_MAPOFF(*offset), curthread->td_ucred);
859 if (vm_obj == NULL) {
860 drm_gem_object_unreference_unlocked(gem_obj);
863 *offset = DRM_GEM_MAPPING_MAPOFF(*offset);