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 <linux/shmem_fs.h>
  38#include <linux/dma-buf.h>
  39#include <linux/mem_encrypt.h>
  40#include <linux/pagevec.h>
  41
  42#include <drm/drm.h>
  43#include <drm/drm_device.h>
  44#include <drm/drm_drv.h>
  45#include <drm/drm_file.h>
  46#include <drm/drm_gem.h>
  47#include <drm/drm_managed.h>
  48#include <drm/drm_print.h>
  49#include <drm/drm_vma_manager.h>
  50
  51#include "drm_internal.h"
  52
  53/** @file drm_gem.c
  54 *
  55 * This file provides some of the base ioctls and library routines for
  56 * the graphics memory manager implemented by each device driver.
  57 *
  58 * Because various devices have different requirements in terms of
  59 * synchronization and migration strategies, implementing that is left up to
  60 * the driver, and all that the general API provides should be generic --
  61 * allocating objects, reading/writing data with the cpu, freeing objects.
  62 * Even there, platform-dependent optimizations for reading/writing data with
  63 * the CPU mean we'll likely hook those out to driver-specific calls.  However,
  64 * the DRI2 implementation wants to have at least allocate/mmap be generic.
  65 *
  66 * The goal was to have swap-backed object allocation managed through
  67 * struct file.  However, file descriptors as handles to a struct file have
  68 * two major failings:
  69 * - Process limits prevent more than 1024 or so being used at a time by
  70 *   default.
  71 * - Inability to allocate high fds will aggravate the X Server's select()
  72 *   handling, and likely that of many GL client applications as well.
  73 *
  74 * This led to a plan of using our own integer IDs (called handles, following
  75 * DRM terminology) to mimic fds, and implement the fd syscalls we need as
  76 * ioctls.  The objects themselves will still include the struct file so
  77 * that we can transition to fds if the required kernel infrastructure shows
  78 * up at a later date, and as our interface with shmfs for memory allocation.
  79 */
  80
  81static void
  82drm_gem_init_release(struct drm_device *dev, void *ptr)
  83{
  84	drm_vma_offset_manager_destroy(dev->vma_offset_manager);
  85}
 
 
 
 
 
 
 
 
 
 
 
  86
  87/**
  88 * drm_gem_init - Initialize the GEM device fields
  89 * @dev: drm_devic structure to initialize
  90 */
  91int
  92drm_gem_init(struct drm_device *dev)
  93{
  94	struct drm_vma_offset_manager *vma_offset_manager;
  95
  96	mutex_init(&dev->object_name_lock);
  97	idr_init_base(&dev->object_name_idr, 1);
  98
  99	vma_offset_manager = drmm_kzalloc(dev, sizeof(*vma_offset_manager),
 100					  GFP_KERNEL);
 101	if (!vma_offset_manager) {
 102		DRM_ERROR("out of memory\n");
 103		return -ENOMEM;
 104	}
 105
 106	dev->vma_offset_manager = vma_offset_manager;
 107	drm_vma_offset_manager_init(vma_offset_manager,
 108				    DRM_FILE_PAGE_OFFSET_START,
 109				    DRM_FILE_PAGE_OFFSET_SIZE);
 110
 111	return drmm_add_action(dev, drm_gem_init_release, NULL);
 
 
 
 
 
 
 
 
 
 112}
 113
 114/**
 115 * drm_gem_object_init - initialize an allocated shmem-backed GEM object
 116 * @dev: drm_device the object should be initialized for
 117 * @obj: drm_gem_object to initialize
 118 * @size: object size
 119 *
 120 * Initialize an already allocated GEM object of the specified size with
 121 * shmfs backing store.
 122 */
 123int drm_gem_object_init(struct drm_device *dev,
 124			struct drm_gem_object *obj, size_t size)
 125{
 126	struct file *filp;
 127
 128	drm_gem_private_object_init(dev, obj, size);
 129
 130	filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
 131	if (IS_ERR(filp))
 132		return PTR_ERR(filp);
 133
 134	obj->filp = filp;
 135
 136	return 0;
 137}
 138EXPORT_SYMBOL(drm_gem_object_init);
 139
 140/**
 141 * drm_gem_private_object_init - initialize an allocated private GEM object
 142 * @dev: drm_device the object should be initialized for
 143 * @obj: drm_gem_object to initialize
 144 * @size: object size
 145 *
 146 * Initialize an already allocated GEM object of the specified size with
 147 * no GEM provided backing store. Instead the caller is responsible for
 148 * backing the object and handling it.
 149 */
 150void drm_gem_private_object_init(struct drm_device *dev,
 151				 struct drm_gem_object *obj, size_t size)
 152{
 153	BUG_ON((size & (PAGE_SIZE - 1)) != 0);
 154
 155	obj->dev = dev;
 156	obj->filp = NULL;
 157
 158	kref_init(&obj->refcount);
 159	obj->handle_count = 0;
 160	obj->size = size;
 161	dma_resv_init(&obj->_resv);
 162	if (!obj->resv)
 163		obj->resv = &obj->_resv;
 164
 165	drm_vma_node_reset(&obj->vma_node);
 166}
 167EXPORT_SYMBOL(drm_gem_private_object_init);
 168
 169static void
 170drm_gem_remove_prime_handles(struct drm_gem_object *obj, struct drm_file *filp)
 171{
 172	/*
 173	 * Note: obj->dma_buf can't disappear as long as we still hold a
 174	 * handle reference in obj->handle_count.
 175	 */
 176	mutex_lock(&filp->prime.lock);
 177	if (obj->dma_buf) {
 178		drm_prime_remove_buf_handle_locked(&filp->prime,
 179						   obj->dma_buf);
 180	}
 181	mutex_unlock(&filp->prime.lock);
 182}
 183
 184/**
 185 * drm_gem_object_handle_free - release resources bound to userspace handles
 186 * @obj: GEM object to clean up.
 187 *
 188 * Called after the last handle to the object has been closed
 189 *
 190 * Removes any name for the object. Note that this must be
 191 * called before drm_gem_object_free or we'll be touching
 192 * freed memory
 193 */
 194static void drm_gem_object_handle_free(struct drm_gem_object *obj)
 195{
 196	struct drm_device *dev = obj->dev;
 197
 198	/* Remove any name for this object */
 199	if (obj->name) {
 200		idr_remove(&dev->object_name_idr, obj->name);
 201		obj->name = 0;
 202	}
 203}
 204
 205static void drm_gem_object_exported_dma_buf_free(struct drm_gem_object *obj)
 206{
 207	/* Unbreak the reference cycle if we have an exported dma_buf. */
 208	if (obj->dma_buf) {
 209		dma_buf_put(obj->dma_buf);
 210		obj->dma_buf = NULL;
 211	}
 212}
 213
 214static void
 215drm_gem_object_handle_put_unlocked(struct drm_gem_object *obj)
 216{
 217	struct drm_device *dev = obj->dev;
 218	bool final = false;
 219
 220	if (WARN_ON(READ_ONCE(obj->handle_count) == 0))
 221		return;
 222
 223	/*
 224	* Must bump handle count first as this may be the last
 225	* ref, in which case the object would disappear before we
 226	* checked for a name
 227	*/
 228
 229	mutex_lock(&dev->object_name_lock);
 230	if (--obj->handle_count == 0) {
 231		drm_gem_object_handle_free(obj);
 232		drm_gem_object_exported_dma_buf_free(obj);
 233		final = true;
 234	}
 235	mutex_unlock(&dev->object_name_lock);
 236
 237	if (final)
 238		drm_gem_object_put(obj);
 239}
 240
 241/*
 242 * Called at device or object close to release the file's
 243 * handle references on objects.
 244 */
 245static int
 246drm_gem_object_release_handle(int id, void *ptr, void *data)
 247{
 248	struct drm_file *file_priv = data;
 249	struct drm_gem_object *obj = ptr;
 250	struct drm_device *dev = obj->dev;
 251
 252	if (obj->funcs && obj->funcs->close)
 253		obj->funcs->close(obj, file_priv);
 254	else if (dev->driver->gem_close_object)
 255		dev->driver->gem_close_object(obj, file_priv);
 256
 257	drm_gem_remove_prime_handles(obj, file_priv);
 258	drm_vma_node_revoke(&obj->vma_node, file_priv);
 259
 260	drm_gem_object_handle_put_unlocked(obj);
 261
 262	return 0;
 263}
 264
 265/**
 266 * drm_gem_handle_delete - deletes the given file-private handle
 267 * @filp: drm file-private structure to use for the handle look up
 268 * @handle: userspace handle to delete
 269 *
 270 * Removes the GEM handle from the @filp lookup table which has been added with
 271 * drm_gem_handle_create(). If this is the last handle also cleans up linked
 272 * resources like GEM names.
 273 */
 274int
 275drm_gem_handle_delete(struct drm_file *filp, u32 handle)
 276{
 
 277	struct drm_gem_object *obj;
 278
 
 
 
 
 
 
 
 
 
 279	spin_lock(&filp->table_lock);
 280
 281	/* Check if we currently have a reference on the object */
 282	obj = idr_replace(&filp->object_idr, NULL, handle);
 283	spin_unlock(&filp->table_lock);
 284	if (IS_ERR_OR_NULL(obj))
 285		return -EINVAL;
 
 
 286
 287	/* Release driver's reference and decrement refcount. */
 288	drm_gem_object_release_handle(handle, obj, filp);
 289
 290	/* And finally make the handle available for future allocations. */
 291	spin_lock(&filp->table_lock);
 292	idr_remove(&filp->object_idr, handle);
 293	spin_unlock(&filp->table_lock);
 294
 
 295	return 0;
 296}
 297EXPORT_SYMBOL(drm_gem_handle_delete);
 298
 299/**
 300 * drm_gem_dumb_map_offset - return the fake mmap offset for a gem object
 301 * @file: drm file-private structure containing the gem object
 302 * @dev: corresponding drm_device
 303 * @handle: gem object handle
 304 * @offset: return location for the fake mmap offset
 305 *
 306 * This implements the &drm_driver.dumb_map_offset kms driver callback for
 307 * drivers which use gem to manage their backing storage.
 308 *
 309 * Returns:
 310 * 0 on success or a negative error code on failure.
 311 */
 312int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
 313			    u32 handle, u64 *offset)
 314{
 315	struct drm_gem_object *obj;
 316	int ret;
 317
 318	obj = drm_gem_object_lookup(file, handle);
 319	if (!obj)
 320		return -ENOENT;
 321
 322	/* Don't allow imported objects to be mapped */
 323	if (obj->import_attach) {
 324		ret = -EINVAL;
 325		goto out;
 326	}
 327
 328	ret = drm_gem_create_mmap_offset(obj);
 329	if (ret)
 330		goto out;
 331
 332	*offset = drm_vma_node_offset_addr(&obj->vma_node);
 333out:
 334	drm_gem_object_put(obj);
 335
 336	return ret;
 337}
 338EXPORT_SYMBOL_GPL(drm_gem_dumb_map_offset);
 339
 340/**
 341 * drm_gem_dumb_destroy - dumb fb callback helper for gem based drivers
 342 * @file: drm file-private structure to remove the dumb handle from
 343 * @dev: corresponding drm_device
 344 * @handle: the dumb handle to remove
 345 *
 346 * This implements the &drm_driver.dumb_destroy kms driver callback for drivers
 347 * which use gem to manage their backing storage.
 348 */
 349int drm_gem_dumb_destroy(struct drm_file *file,
 350			 struct drm_device *dev,
 351			 uint32_t handle)
 352{
 353	return drm_gem_handle_delete(file, handle);
 354}
 355EXPORT_SYMBOL(drm_gem_dumb_destroy);
 356
 357/**
 358 * drm_gem_handle_create_tail - internal functions to create a handle
 359 * @file_priv: drm file-private structure to register the handle for
 360 * @obj: object to register
 361 * @handlep: pointer to return the created handle to the caller
 362 *
 363 * This expects the &drm_device.object_name_lock to be held already and will
 364 * drop it before returning. Used to avoid races in establishing new handles
 365 * when importing an object from either an flink name or a dma-buf.
 366 *
 367 * Handles must be release again through drm_gem_handle_delete(). This is done
 368 * when userspace closes @file_priv for all attached handles, or through the
 369 * GEM_CLOSE ioctl for individual handles.
 370 */
 371int
 372drm_gem_handle_create_tail(struct drm_file *file_priv,
 373			   struct drm_gem_object *obj,
 374			   u32 *handlep)
 375{
 376	struct drm_device *dev = obj->dev;
 377	u32 handle;
 378	int ret;
 379
 380	WARN_ON(!mutex_is_locked(&dev->object_name_lock));
 381	if (obj->handle_count++ == 0)
 382		drm_gem_object_get(obj);
 383
 384	/*
 385	 * Get the user-visible handle using idr.  Preload and perform
 386	 * allocation under our spinlock.
 387	 */
 388	idr_preload(GFP_KERNEL);
 389	spin_lock(&file_priv->table_lock);
 390
 391	ret = idr_alloc(&file_priv->object_idr, obj, 1, 0, GFP_NOWAIT);
 392
 393	spin_unlock(&file_priv->table_lock);
 394	idr_preload_end();
 395
 396	mutex_unlock(&dev->object_name_lock);
 397	if (ret < 0)
 398		goto err_unref;
 399
 400	handle = ret;
 401
 402	ret = drm_vma_node_allow(&obj->vma_node, file_priv);
 403	if (ret)
 404		goto err_remove;
 405
 406	if (obj->funcs && obj->funcs->open) {
 407		ret = obj->funcs->open(obj, file_priv);
 408		if (ret)
 409			goto err_revoke;
 410	} else if (dev->driver->gem_open_object) {
 411		ret = dev->driver->gem_open_object(obj, file_priv);
 412		if (ret)
 413			goto err_revoke;
 414	}
 415
 416	*handlep = handle;
 417	return 0;
 418
 419err_revoke:
 420	drm_vma_node_revoke(&obj->vma_node, file_priv);
 421err_remove:
 422	spin_lock(&file_priv->table_lock);
 423	idr_remove(&file_priv->object_idr, handle);
 424	spin_unlock(&file_priv->table_lock);
 425err_unref:
 426	drm_gem_object_handle_put_unlocked(obj);
 427	return ret;
 428}
 429
 430/**
 431 * drm_gem_handle_create - create a gem handle for an object
 432 * @file_priv: drm file-private structure to register the handle for
 433 * @obj: object to register
 434 * @handlep: pointer to return the created handle to the caller
 435 *
 436 * Create a handle for this object. This adds a handle reference to the object,
 437 * which includes a regular reference count. Callers will likely want to
 438 * dereference the object afterwards.
 439 *
 440 * Since this publishes @obj to userspace it must be fully set up by this point,
 441 * drivers must call this last in their buffer object creation callbacks.
 
 442 */
 443int drm_gem_handle_create(struct drm_file *file_priv,
 444			  struct drm_gem_object *obj,
 445			  u32 *handlep)
 446{
 447	mutex_lock(&obj->dev->object_name_lock);
 448
 449	return drm_gem_handle_create_tail(file_priv, obj, handlep);
 450}
 451EXPORT_SYMBOL(drm_gem_handle_create);
 452
 453
 454/**
 455 * drm_gem_free_mmap_offset - release a fake mmap offset for an object
 456 * @obj: obj in question
 457 *
 458 * This routine frees fake offsets allocated by drm_gem_create_mmap_offset().
 459 *
 460 * Note that drm_gem_object_release() already calls this function, so drivers
 461 * don't have to take care of releasing the mmap offset themselves when freeing
 462 * the GEM object.
 463 */
 464void
 465drm_gem_free_mmap_offset(struct drm_gem_object *obj)
 466{
 467	struct drm_device *dev = obj->dev;
 468
 469	drm_vma_offset_remove(dev->vma_offset_manager, &obj->vma_node);
 470}
 471EXPORT_SYMBOL(drm_gem_free_mmap_offset);
 472
 473/**
 474 * drm_gem_create_mmap_offset_size - create a fake mmap offset for an object
 475 * @obj: obj in question
 476 * @size: the virtual size
 477 *
 478 * GEM memory mapping works by handing back to userspace a fake mmap offset
 479 * it can use in a subsequent mmap(2) call.  The DRM core code then looks
 480 * up the object based on the offset and sets up the various memory mapping
 481 * structures.
 482 *
 483 * This routine allocates and attaches a fake offset for @obj, in cases where
 484 * the virtual size differs from the physical size (ie. &drm_gem_object.size).
 485 * Otherwise just use drm_gem_create_mmap_offset().
 486 *
 487 * This function is idempotent and handles an already allocated mmap offset
 488 * transparently. Drivers do not need to check for this case.
 489 */
 490int
 491drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size)
 492{
 493	struct drm_device *dev = obj->dev;
 494
 495	return drm_vma_offset_add(dev->vma_offset_manager, &obj->vma_node,
 496				  size / PAGE_SIZE);
 497}
 498EXPORT_SYMBOL(drm_gem_create_mmap_offset_size);
 499
 500/**
 501 * drm_gem_create_mmap_offset - create a fake mmap offset for an object
 502 * @obj: obj in question
 503 *
 504 * GEM memory mapping works by handing back to userspace a fake mmap offset
 505 * it can use in a subsequent mmap(2) call.  The DRM core code then looks
 506 * up the object based on the offset and sets up the various memory mapping
 507 * structures.
 508 *
 509 * This routine allocates and attaches a fake offset for @obj.
 510 *
 511 * Drivers can call drm_gem_free_mmap_offset() before freeing @obj to release
 512 * the fake offset again.
 513 */
 514int drm_gem_create_mmap_offset(struct drm_gem_object *obj)
 515{
 516	return drm_gem_create_mmap_offset_size(obj, obj->size);
 517}
 518EXPORT_SYMBOL(drm_gem_create_mmap_offset);
 519
 520/*
 521 * Move pages to appropriate lru and release the pagevec, decrementing the
 522 * ref count of those pages.
 523 */
 524static void drm_gem_check_release_pagevec(struct pagevec *pvec)
 525{
 526	check_move_unevictable_pages(pvec);
 527	__pagevec_release(pvec);
 528	cond_resched();
 529}
 530
 531/**
 532 * drm_gem_get_pages - helper to allocate backing pages for a GEM object
 533 * from shmem
 534 * @obj: obj in question
 535 *
 536 * This reads the page-array of the shmem-backing storage of the given gem
 537 * object. An array of pages is returned. If a page is not allocated or
 538 * swapped-out, this will allocate/swap-in the required pages. Note that the
 539 * whole object is covered by the page-array and pinned in memory.
 540 *
 541 * Use drm_gem_put_pages() to release the array and unpin all pages.
 542 *
 543 * This uses the GFP-mask set on the shmem-mapping (see mapping_set_gfp_mask()).
 544 * If you require other GFP-masks, you have to do those allocations yourself.
 545 *
 546 * Note that you are not allowed to change gfp-zones during runtime. That is,
 547 * shmem_read_mapping_page_gfp() must be called with the same gfp_zone(gfp) as
 548 * set during initialization. If you have special zone constraints, set them
 549 * after drm_gem_object_init() via mapping_set_gfp_mask(). shmem-core takes care
 550 * to keep pages in the required zone during swap-in.
 551 *
 552 * This function is only valid on objects initialized with
 553 * drm_gem_object_init(), but not for those initialized with
 554 * drm_gem_private_object_init() only.
 555 */
 556struct page **drm_gem_get_pages(struct drm_gem_object *obj)
 557{
 558	struct address_space *mapping;
 559	struct page *p, **pages;
 560	struct pagevec pvec;
 561	int i, npages;
 562
 563
 564	if (WARN_ON(!obj->filp))
 565		return ERR_PTR(-EINVAL);
 566
 567	/* This is the shared memory object that backs the GEM resource */
 568	mapping = obj->filp->f_mapping;
 569
 570	/* We already BUG_ON() for non-page-aligned sizes in
 571	 * drm_gem_object_init(), so we should never hit this unless
 572	 * driver author is doing something really wrong:
 573	 */
 574	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
 575
 576	npages = obj->size >> PAGE_SHIFT;
 577
 578	pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
 579	if (pages == NULL)
 580		return ERR_PTR(-ENOMEM);
 581
 582	mapping_set_unevictable(mapping);
 583
 584	for (i = 0; i < npages; i++) {
 585		p = shmem_read_mapping_page(mapping, i);
 586		if (IS_ERR(p))
 587			goto fail;
 588		pages[i] = p;
 589
 590		/* Make sure shmem keeps __GFP_DMA32 allocated pages in the
 591		 * correct region during swapin. Note that this requires
 592		 * __GFP_DMA32 to be set in mapping_gfp_mask(inode->i_mapping)
 593		 * so shmem can relocate pages during swapin if required.
 594		 */
 595		BUG_ON(mapping_gfp_constraint(mapping, __GFP_DMA32) &&
 596				(page_to_pfn(p) >= 0x00100000UL));
 597	}
 598
 599	return pages;
 600
 601fail:
 602	mapping_clear_unevictable(mapping);
 603	pagevec_init(&pvec);
 604	while (i--) {
 605		if (!pagevec_add(&pvec, pages[i]))
 606			drm_gem_check_release_pagevec(&pvec);
 607	}
 608	if (pagevec_count(&pvec))
 609		drm_gem_check_release_pagevec(&pvec);
 610
 611	kvfree(pages);
 612	return ERR_CAST(p);
 613}
 614EXPORT_SYMBOL(drm_gem_get_pages);
 615
 616/**
 617 * drm_gem_put_pages - helper to free backing pages for a GEM object
 618 * @obj: obj in question
 619 * @pages: pages to free
 620 * @dirty: if true, pages will be marked as dirty
 621 * @accessed: if true, the pages will be marked as accessed
 622 */
 623void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
 624		bool dirty, bool accessed)
 625{
 626	int i, npages;
 627	struct address_space *mapping;
 628	struct pagevec pvec;
 629
 630	mapping = file_inode(obj->filp)->i_mapping;
 631	mapping_clear_unevictable(mapping);
 632
 633	/* We already BUG_ON() for non-page-aligned sizes in
 634	 * drm_gem_object_init(), so we should never hit this unless
 635	 * driver author is doing something really wrong:
 636	 */
 637	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
 638
 639	npages = obj->size >> PAGE_SHIFT;
 640
 641	pagevec_init(&pvec);
 642	for (i = 0; i < npages; i++) {
 643		if (!pages[i])
 644			continue;
 645
 646		if (dirty)
 647			set_page_dirty(pages[i]);
 648
 649		if (accessed)
 650			mark_page_accessed(pages[i]);
 651
 652		/* Undo the reference we took when populating the table */
 653		if (!pagevec_add(&pvec, pages[i]))
 654			drm_gem_check_release_pagevec(&pvec);
 655	}
 656	if (pagevec_count(&pvec))
 657		drm_gem_check_release_pagevec(&pvec);
 658
 659	kvfree(pages);
 660}
 661EXPORT_SYMBOL(drm_gem_put_pages);
 662
 663static int objects_lookup(struct drm_file *filp, u32 *handle, int count,
 664			  struct drm_gem_object **objs)
 665{
 666	int i, ret = 0;
 667	struct drm_gem_object *obj;
 668
 669	spin_lock(&filp->table_lock);
 670
 671	for (i = 0; i < count; i++) {
 672		/* Check if we currently have a reference on the object */
 673		obj = idr_find(&filp->object_idr, handle[i]);
 674		if (!obj) {
 675			ret = -ENOENT;
 676			break;
 677		}
 678		drm_gem_object_get(obj);
 679		objs[i] = obj;
 680	}
 681	spin_unlock(&filp->table_lock);
 682
 683	return ret;
 684}
 685
 686/**
 687 * drm_gem_objects_lookup - look up GEM objects from an array of handles
 688 * @filp: DRM file private date
 689 * @bo_handles: user pointer to array of userspace handle
 690 * @count: size of handle array
 691 * @objs_out: returned pointer to array of drm_gem_object pointers
 692 *
 693 * Takes an array of userspace handles and returns a newly allocated array of
 694 * GEM objects.
 695 *
 696 * For a single handle lookup, use drm_gem_object_lookup().
 697 *
 698 * Returns:
 699 *
 700 * @objs filled in with GEM object pointers. Returned GEM objects need to be
 701 * released with drm_gem_object_put(). -ENOENT is returned on a lookup
 702 * failure. 0 is returned on success.
 703 *
 704 */
 705int drm_gem_objects_lookup(struct drm_file *filp, void __user *bo_handles,
 706			   int count, struct drm_gem_object ***objs_out)
 707{
 708	int ret;
 709	u32 *handles;
 710	struct drm_gem_object **objs;
 711
 712	if (!count)
 713		return 0;
 714
 715	objs = kvmalloc_array(count, sizeof(struct drm_gem_object *),
 716			     GFP_KERNEL | __GFP_ZERO);
 717	if (!objs)
 718		return -ENOMEM;
 719
 720	*objs_out = objs;
 721
 722	handles = kvmalloc_array(count, sizeof(u32), GFP_KERNEL);
 723	if (!handles) {
 724		ret = -ENOMEM;
 725		goto out;
 726	}
 727
 728	if (copy_from_user(handles, bo_handles, count * sizeof(u32))) {
 729		ret = -EFAULT;
 730		DRM_DEBUG("Failed to copy in GEM handles\n");
 731		goto out;
 732	}
 733
 734	ret = objects_lookup(filp, handles, count, objs);
 735out:
 736	kvfree(handles);
 737	return ret;
 738
 739}
 740EXPORT_SYMBOL(drm_gem_objects_lookup);
 741
 742/**
 743 * drm_gem_object_lookup - look up a GEM object from its handle
 744 * @filp: DRM file private date
 745 * @handle: userspace handle
 746 *
 747 * Returns:
 748 *
 749 * A reference to the object named by the handle if such exists on @filp, NULL
 750 * otherwise.
 751 *
 752 * If looking up an array of handles, use drm_gem_objects_lookup().
 753 */
 754struct drm_gem_object *
 755drm_gem_object_lookup(struct drm_file *filp, u32 handle)
 
 756{
 757	struct drm_gem_object *obj = NULL;
 758
 759	objects_lookup(filp, &handle, 1, &obj);
 760	return obj;
 761}
 762EXPORT_SYMBOL(drm_gem_object_lookup);
 763
 764/**
 765 * drm_gem_dma_resv_wait - Wait on GEM object's reservation's objects
 766 * shared and/or exclusive fences.
 767 * @filep: DRM file private date
 768 * @handle: userspace handle
 769 * @wait_all: if true, wait on all fences, else wait on just exclusive fence
 770 * @timeout: timeout value in jiffies or zero to return immediately
 771 *
 772 * Returns:
 773 *
 774 * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
 775 * greater than 0 on success.
 776 */
 777long drm_gem_dma_resv_wait(struct drm_file *filep, u32 handle,
 778				    bool wait_all, unsigned long timeout)
 779{
 780	long ret;
 781	struct drm_gem_object *obj;
 782
 783	obj = drm_gem_object_lookup(filep, handle);
 784	if (!obj) {
 785		DRM_DEBUG("Failed to look up GEM BO %d\n", handle);
 786		return -EINVAL;
 
 
 
 787	}
 788
 789	ret = dma_resv_wait_timeout_rcu(obj->resv, wait_all,
 790						  true, timeout);
 791	if (ret == 0)
 792		ret = -ETIME;
 793	else if (ret > 0)
 794		ret = 0;
 795
 796	drm_gem_object_put(obj);
 797
 798	return ret;
 799}
 800EXPORT_SYMBOL(drm_gem_dma_resv_wait);
 801
 802/**
 803 * drm_gem_close_ioctl - implementation of the GEM_CLOSE ioctl
 804 * @dev: drm_device
 805 * @data: ioctl data
 806 * @file_priv: drm file-private structure
 807 *
 808 * Releases the handle to an mm object.
 809 */
 810int
 811drm_gem_close_ioctl(struct drm_device *dev, void *data,
 812		    struct drm_file *file_priv)
 813{
 814	struct drm_gem_close *args = data;
 815	int ret;
 816
 817	if (!drm_core_check_feature(dev, DRIVER_GEM))
 818		return -EOPNOTSUPP;
 819
 820	ret = drm_gem_handle_delete(file_priv, args->handle);
 821
 822	return ret;
 823}
 824
 825/**
 826 * drm_gem_flink_ioctl - implementation of the GEM_FLINK ioctl
 827 * @dev: drm_device
 828 * @data: ioctl data
 829 * @file_priv: drm file-private structure
 830 *
 831 * Create a global name for an object, returning the name.
 832 *
 833 * Note that the name does not hold a reference; when the object
 834 * is freed, the name goes away.
 835 */
 836int
 837drm_gem_flink_ioctl(struct drm_device *dev, void *data,
 838		    struct drm_file *file_priv)
 839{
 840	struct drm_gem_flink *args = data;
 841	struct drm_gem_object *obj;
 842	int ret;
 843
 844	if (!drm_core_check_feature(dev, DRIVER_GEM))
 845		return -EOPNOTSUPP;
 846
 847	obj = drm_gem_object_lookup(file_priv, args->handle);
 848	if (obj == NULL)
 849		return -ENOENT;
 850
 851	mutex_lock(&dev->object_name_lock);
 852	/* prevent races with concurrent gem_close. */
 853	if (obj->handle_count == 0) {
 854		ret = -ENOENT;
 855		goto err;
 856	}
 857
 858	if (!obj->name) {
 859		ret = idr_alloc(&dev->object_name_idr, obj, 1, 0, GFP_KERNEL);
 860		if (ret < 0)
 861			goto err;
 862
 863		obj->name = ret;
 864	}
 865
 866	args->name = (uint64_t) obj->name;
 867	ret = 0;
 868
 869err:
 870	mutex_unlock(&dev->object_name_lock);
 871	drm_gem_object_put(obj);
 872	return ret;
 873}
 874
 875/**
 876 * drm_gem_open - implementation of the GEM_OPEN ioctl
 877 * @dev: drm_device
 878 * @data: ioctl data
 879 * @file_priv: drm file-private structure
 880 *
 881 * Open an object using the global name, returning a handle and the size.
 882 *
 883 * This handle (of course) holds a reference to the object, so the object
 884 * will not go away until the handle is deleted.
 885 */
 886int
 887drm_gem_open_ioctl(struct drm_device *dev, void *data,
 888		   struct drm_file *file_priv)
 889{
 890	struct drm_gem_open *args = data;
 891	struct drm_gem_object *obj;
 892	int ret;
 893	u32 handle;
 894
 895	if (!drm_core_check_feature(dev, DRIVER_GEM))
 896		return -EOPNOTSUPP;
 897
 898	mutex_lock(&dev->object_name_lock);
 899	obj = idr_find(&dev->object_name_idr, (int) args->name);
 900	if (obj) {
 901		drm_gem_object_get(obj);
 902	} else {
 903		mutex_unlock(&dev->object_name_lock);
 904		return -ENOENT;
 905	}
 906
 907	/* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
 908	ret = drm_gem_handle_create_tail(file_priv, obj, &handle);
 
 909	if (ret)
 910		goto err;
 911
 912	args->handle = handle;
 913	args->size = obj->size;
 914
 915err:
 916	drm_gem_object_put(obj);
 917	return ret;
 918}
 919
 920/**
 921 * gem_gem_open - initalizes GEM file-private structures at devnode open time
 922 * @dev: drm_device which is being opened by userspace
 923 * @file_private: drm file-private structure to set up
 924 *
 925 * Called at device open time, sets up the structure for handling refcounting
 926 * of mm objects.
 927 */
 928void
 929drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
 930{
 931	idr_init_base(&file_private->object_idr, 1);
 932	spin_lock_init(&file_private->table_lock);
 933}
 934
 935/**
 936 * drm_gem_release - release file-private GEM resources
 937 * @dev: drm_device which is being closed by userspace
 938 * @file_private: drm file-private structure to clean up
 939 *
 940 * Called at close time when the filp is going away.
 941 *
 942 * Releases any remaining references on objects by this filp.
 943 */
 944void
 945drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
 946{
 947	idr_for_each(&file_private->object_idr,
 948		     &drm_gem_object_release_handle, file_private);
 949	idr_destroy(&file_private->object_idr);
 950}
 951
 952/**
 953 * drm_gem_object_release - release GEM buffer object resources
 954 * @obj: GEM buffer object
 955 *
 956 * This releases any structures and resources used by @obj and is the invers of
 957 * drm_gem_object_init().
 958 */
 959void
 960drm_gem_object_release(struct drm_gem_object *obj)
 961{
 962	WARN_ON(obj->dma_buf);
 963
 964	if (obj->filp)
 965		fput(obj->filp);
 966
 967	dma_resv_fini(&obj->_resv);
 968	drm_gem_free_mmap_offset(obj);
 969}
 970EXPORT_SYMBOL(drm_gem_object_release);
 971
 972/**
 973 * drm_gem_object_free - free a GEM object
 974 * @kref: kref of the object to free
 975 *
 976 * Called after the last reference to the object has been lost.
 
 977 *
 978 * Frees the object
 979 */
 980void
 981drm_gem_object_free(struct kref *kref)
 982{
 983	struct drm_gem_object *obj =
 984		container_of(kref, struct drm_gem_object, refcount);
 985	struct drm_device *dev = obj->dev;
 986
 987	if (obj->funcs)
 988		obj->funcs->free(obj);
 989	else if (dev->driver->gem_free_object_unlocked)
 990		dev->driver->gem_free_object_unlocked(obj);
 991}
 992EXPORT_SYMBOL(drm_gem_object_free);
 993
 994/**
 995 * drm_gem_object_put_locked - release a GEM buffer object reference
 996 * @obj: GEM buffer object
 997 *
 998 * This releases a reference to @obj. Callers must hold the
 999 * &drm_device.struct_mutex lock when calling this function, even when the
1000 * driver doesn't use &drm_device.struct_mutex for anything.
1001 *
1002 * For drivers not encumbered with legacy locking use
1003 * drm_gem_object_put() instead.
1004 */
1005void
1006drm_gem_object_put_locked(struct drm_gem_object *obj)
1007{
1008	if (obj) {
1009		WARN_ON(!mutex_is_locked(&obj->dev->struct_mutex));
1010
1011		kref_put(&obj->refcount, drm_gem_object_free);
1012	}
1013}
1014EXPORT_SYMBOL(drm_gem_object_put_locked);
1015
1016/**
1017 * drm_gem_vm_open - vma->ops->open implementation for GEM
1018 * @vma: VM area structure
1019 *
1020 * This function implements the #vm_operations_struct open() callback for GEM
1021 * drivers. This must be used together with drm_gem_vm_close().
1022 */
1023void drm_gem_vm_open(struct vm_area_struct *vma)
1024{
1025	struct drm_gem_object *obj = vma->vm_private_data;
1026
1027	drm_gem_object_get(obj);
1028}
1029EXPORT_SYMBOL(drm_gem_vm_open);
1030
1031/**
1032 * drm_gem_vm_close - vma->ops->close implementation for GEM
1033 * @vma: VM area structure
1034 *
1035 * This function implements the #vm_operations_struct close() callback for GEM
1036 * drivers. This must be used together with drm_gem_vm_open().
1037 */
1038void drm_gem_vm_close(struct vm_area_struct *vma)
1039{
1040	struct drm_gem_object *obj = vma->vm_private_data;
1041
1042	drm_gem_object_put(obj);
1043}
1044EXPORT_SYMBOL(drm_gem_vm_close);
1045
1046/**
1047 * drm_gem_mmap_obj - memory map a GEM object
1048 * @obj: the GEM object to map
1049 * @obj_size: the object size to be mapped, in bytes
1050 * @vma: VMA for the area to be mapped
1051 *
1052 * Set up the VMA to prepare mapping of the GEM object using the gem_vm_ops
1053 * provided by the driver. Depending on their requirements, drivers can either
1054 * provide a fault handler in their gem_vm_ops (in which case any accesses to
1055 * the object will be trapped, to perform migration, GTT binding, surface
1056 * register allocation, or performance monitoring), or mmap the buffer memory
1057 * synchronously after calling drm_gem_mmap_obj.
1058 *
1059 * This function is mainly intended to implement the DMABUF mmap operation, when
1060 * the GEM object is not looked up based on its fake offset. To implement the
1061 * DRM mmap operation, drivers should use the drm_gem_mmap() function.
1062 *
1063 * drm_gem_mmap_obj() assumes the user is granted access to the buffer while
1064 * drm_gem_mmap() prevents unprivileged users from mapping random objects. So
1065 * callers must verify access restrictions before calling this helper.
1066 *
1067 * Return 0 or success or -EINVAL if the object size is smaller than the VMA
1068 * size, or if no gem_vm_ops are provided.
1069 */
1070int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
1071		     struct vm_area_struct *vma)
1072{
1073	struct drm_device *dev = obj->dev;
1074	int ret;
1075
1076	/* Check for valid size. */
1077	if (obj_size < vma->vm_end - vma->vm_start)
1078		return -EINVAL;
1079
 
 
 
 
 
 
 
 
1080	/* Take a ref for this mapping of the object, so that the fault
1081	 * handler can dereference the mmap offset's pointer to the object.
1082	 * This reference is cleaned up by the corresponding vm_close
1083	 * (which should happen whether the vma was created by this call, or
1084	 * by a vm_open due to mremap or partial unmap or whatever).
1085	 */
1086	drm_gem_object_get(obj);
1087
1088	if (obj->funcs && obj->funcs->mmap) {
1089		ret = obj->funcs->mmap(obj, vma);
1090		if (ret) {
1091			drm_gem_object_put(obj);
1092			return ret;
1093		}
1094		WARN_ON(!(vma->vm_flags & VM_DONTEXPAND));
1095	} else {
1096		if (obj->funcs && obj->funcs->vm_ops)
1097			vma->vm_ops = obj->funcs->vm_ops;
1098		else if (dev->driver->gem_vm_ops)
1099			vma->vm_ops = dev->driver->gem_vm_ops;
1100		else {
1101			drm_gem_object_put(obj);
1102			return -EINVAL;
1103		}
1104
1105		vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1106		vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
1107		vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
1108	}
1109
1110	vma->vm_private_data = obj;
1111
1112	return 0;
1113}
1114EXPORT_SYMBOL(drm_gem_mmap_obj);
1115
1116/**
1117 * drm_gem_mmap - memory map routine for GEM objects
1118 * @filp: DRM file pointer
1119 * @vma: VMA for the area to be mapped
1120 *
1121 * If a driver supports GEM object mapping, mmap calls on the DRM file
1122 * descriptor will end up here.
1123 *
1124 * Look up the GEM object based on the offset passed in (vma->vm_pgoff will
1125 * contain the fake offset we created when the GTT map ioctl was called on
1126 * the object) and map it with a call to drm_gem_mmap_obj().
1127 *
1128 * If the caller is not granted access to the buffer object, the mmap will fail
1129 * with EACCES. Please see the vma manager for more information.
1130 */
1131int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
1132{
1133	struct drm_file *priv = filp->private_data;
1134	struct drm_device *dev = priv->minor->dev;
1135	struct drm_gem_object *obj = NULL;
1136	struct drm_vma_offset_node *node;
1137	int ret;
1138
1139	if (drm_dev_is_unplugged(dev))
1140		return -ENODEV;
1141
1142	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
1143	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
1144						  vma->vm_pgoff,
1145						  vma_pages(vma));
1146	if (likely(node)) {
1147		obj = container_of(node, struct drm_gem_object, vma_node);
1148		/*
1149		 * When the object is being freed, after it hits 0-refcnt it
1150		 * proceeds to tear down the object. In the process it will
1151		 * attempt to remove the VMA offset and so acquire this
1152		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
1153		 * that matches our range, we know it is in the process of being
1154		 * destroyed and will be freed as soon as we release the lock -
1155		 * so we have to check for the 0-refcnted object and treat it as
1156		 * invalid.
1157		 */
1158		if (!kref_get_unless_zero(&obj->refcount))
1159			obj = NULL;
1160	}
1161	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
1162
1163	if (!obj)
1164		return -EINVAL;
1165
1166	if (!drm_vma_node_is_allowed(node, priv)) {
1167		drm_gem_object_put(obj);
1168		return -EACCES;
1169	}
1170
1171	if (node->readonly) {
1172		if (vma->vm_flags & VM_WRITE) {
1173			drm_gem_object_put(obj);
1174			return -EINVAL;
1175		}
1176
1177		vma->vm_flags &= ~VM_MAYWRITE;
1178	}
1179
1180	ret = drm_gem_mmap_obj(obj, drm_vma_node_size(node) << PAGE_SHIFT,
1181			       vma);
1182
1183	drm_gem_object_put(obj);
1184
1185	return ret;
1186}
1187EXPORT_SYMBOL(drm_gem_mmap);
1188
1189void drm_gem_print_info(struct drm_printer *p, unsigned int indent,
1190			const struct drm_gem_object *obj)
1191{
1192	drm_printf_indent(p, indent, "name=%d\n", obj->name);
1193	drm_printf_indent(p, indent, "refcount=%u\n",
1194			  kref_read(&obj->refcount));
1195	drm_printf_indent(p, indent, "start=%08lx\n",
1196			  drm_vma_node_start(&obj->vma_node));
1197	drm_printf_indent(p, indent, "size=%zu\n", obj->size);
1198	drm_printf_indent(p, indent, "imported=%s\n",
1199			  obj->import_attach ? "yes" : "no");
1200
1201	if (obj->funcs && obj->funcs->print_info)
1202		obj->funcs->print_info(p, indent, obj);
1203}
1204
1205int drm_gem_pin(struct drm_gem_object *obj)
1206{
1207	if (obj->funcs && obj->funcs->pin)
1208		return obj->funcs->pin(obj);
1209	else if (obj->dev->driver->gem_prime_pin)
1210		return obj->dev->driver->gem_prime_pin(obj);
1211	else
1212		return 0;
1213}
1214
1215void drm_gem_unpin(struct drm_gem_object *obj)
1216{
1217	if (obj->funcs && obj->funcs->unpin)
1218		obj->funcs->unpin(obj);
1219	else if (obj->dev->driver->gem_prime_unpin)
1220		obj->dev->driver->gem_prime_unpin(obj);
1221}
1222
1223void *drm_gem_vmap(struct drm_gem_object *obj)
1224{
1225	void *vaddr;
1226
1227	if (obj->funcs && obj->funcs->vmap)
1228		vaddr = obj->funcs->vmap(obj);
1229	else if (obj->dev->driver->gem_prime_vmap)
1230		vaddr = obj->dev->driver->gem_prime_vmap(obj);
1231	else
1232		vaddr = ERR_PTR(-EOPNOTSUPP);
1233
1234	if (!vaddr)
1235		vaddr = ERR_PTR(-ENOMEM);
1236
1237	return vaddr;
1238}
1239
1240void drm_gem_vunmap(struct drm_gem_object *obj, void *vaddr)
1241{
1242	if (!vaddr)
1243		return;
1244
1245	if (obj->funcs && obj->funcs->vunmap)
1246		obj->funcs->vunmap(obj, vaddr);
1247	else if (obj->dev->driver->gem_prime_vunmap)
1248		obj->dev->driver->gem_prime_vunmap(obj, vaddr);
1249}
1250
1251/**
1252 * drm_gem_lock_reservations - Sets up the ww context and acquires
1253 * the lock on an array of GEM objects.
1254 *
1255 * Once you've locked your reservations, you'll want to set up space
1256 * for your shared fences (if applicable), submit your job, then
1257 * drm_gem_unlock_reservations().
1258 *
1259 * @objs: drm_gem_objects to lock
1260 * @count: Number of objects in @objs
1261 * @acquire_ctx: struct ww_acquire_ctx that will be initialized as
1262 * part of tracking this set of locked reservations.
1263 */
1264int
1265drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
1266			  struct ww_acquire_ctx *acquire_ctx)
1267{
1268	int contended = -1;
1269	int i, ret;
1270
1271	ww_acquire_init(acquire_ctx, &reservation_ww_class);
1272
1273retry:
1274	if (contended != -1) {
1275		struct drm_gem_object *obj = objs[contended];
1276
1277		ret = dma_resv_lock_slow_interruptible(obj->resv,
1278								 acquire_ctx);
1279		if (ret) {
1280			ww_acquire_done(acquire_ctx);
1281			return ret;
1282		}
1283	}
1284
1285	for (i = 0; i < count; i++) {
1286		if (i == contended)
1287			continue;
1288
1289		ret = dma_resv_lock_interruptible(objs[i]->resv,
1290							    acquire_ctx);
1291		if (ret) {
1292			int j;
1293
1294			for (j = 0; j < i; j++)
1295				dma_resv_unlock(objs[j]->resv);
1296
1297			if (contended != -1 && contended >= i)
1298				dma_resv_unlock(objs[contended]->resv);
1299
1300			if (ret == -EDEADLK) {
1301				contended = i;
1302				goto retry;
1303			}
1304
1305			ww_acquire_done(acquire_ctx);
1306			return ret;
1307		}
1308	}
1309
1310	ww_acquire_done(acquire_ctx);
1311
1312	return 0;
1313}
1314EXPORT_SYMBOL(drm_gem_lock_reservations);
1315
1316void
1317drm_gem_unlock_reservations(struct drm_gem_object **objs, int count,
1318			    struct ww_acquire_ctx *acquire_ctx)
1319{
1320	int i;
1321
1322	for (i = 0; i < count; i++)
1323		dma_resv_unlock(objs[i]->resv);
1324
1325	ww_acquire_fini(acquire_ctx);
1326}
1327EXPORT_SYMBOL(drm_gem_unlock_reservations);
1328
1329/**
1330 * drm_gem_fence_array_add - Adds the fence to an array of fences to be
1331 * waited on, deduplicating fences from the same context.
1332 *
1333 * @fence_array: array of dma_fence * for the job to block on.
1334 * @fence: the dma_fence to add to the list of dependencies.
1335 *
1336 * Returns:
1337 * 0 on success, or an error on failing to expand the array.
1338 */
1339int drm_gem_fence_array_add(struct xarray *fence_array,
1340			    struct dma_fence *fence)
1341{
1342	struct dma_fence *entry;
1343	unsigned long index;
1344	u32 id = 0;
1345	int ret;
1346
1347	if (!fence)
1348		return 0;
1349
1350	/* Deduplicate if we already depend on a fence from the same context.
1351	 * This lets the size of the array of deps scale with the number of
1352	 * engines involved, rather than the number of BOs.
1353	 */
1354	xa_for_each(fence_array, index, entry) {
1355		if (entry->context != fence->context)
1356			continue;
1357
1358		if (dma_fence_is_later(fence, entry)) {
1359			dma_fence_put(entry);
1360			xa_store(fence_array, index, fence, GFP_KERNEL);
1361		} else {
1362			dma_fence_put(fence);
1363		}
1364		return 0;
1365	}
1366
1367	ret = xa_alloc(fence_array, &id, fence, xa_limit_32b, GFP_KERNEL);
1368	if (ret != 0)
1369		dma_fence_put(fence);
1370
1371	return ret;
1372}
1373EXPORT_SYMBOL(drm_gem_fence_array_add);
1374
1375/**
1376 * drm_gem_fence_array_add_implicit - Adds the implicit dependencies tracked
1377 * in the GEM object's reservation object to an array of dma_fences for use in
1378 * scheduling a rendering job.
1379 *
1380 * This should be called after drm_gem_lock_reservations() on your array of
1381 * GEM objects used in the job but before updating the reservations with your
1382 * own fences.
1383 *
1384 * @fence_array: array of dma_fence * for the job to block on.
1385 * @obj: the gem object to add new dependencies from.
1386 * @write: whether the job might write the object (so we need to depend on
1387 * shared fences in the reservation object).
1388 */
1389int drm_gem_fence_array_add_implicit(struct xarray *fence_array,
1390				     struct drm_gem_object *obj,
1391				     bool write)
1392{
1393	int ret;
1394	struct dma_fence **fences;
1395	unsigned int i, fence_count;
1396
1397	if (!write) {
1398		struct dma_fence *fence =
1399			dma_resv_get_excl_rcu(obj->resv);
1400
1401		return drm_gem_fence_array_add(fence_array, fence);
1402	}
1403
1404	ret = dma_resv_get_fences_rcu(obj->resv, NULL,
1405						&fence_count, &fences);
1406	if (ret || !fence_count)
1407		return ret;
1408
1409	for (i = 0; i < fence_count; i++) {
1410		ret = drm_gem_fence_array_add(fence_array, fences[i]);
1411		if (ret)
1412			break;
1413	}
1414
1415	for (; i < fence_count; i++)
1416		dma_fence_put(fences[i]);
1417	kfree(fences);
1418	return ret;
1419}
1420EXPORT_SYMBOL(drm_gem_fence_array_add_implicit);