xref: /openbmc/linux/drivers/gpu/drm/drm_gem.c (revision b7fd68ab)
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/dma-buf.h>
29 #include <linux/file.h>
30 #include <linux/fs.h>
31 #include <linux/iosys-map.h>
32 #include <linux/mem_encrypt.h>
33 #include <linux/mm.h>
34 #include <linux/mman.h>
35 #include <linux/module.h>
36 #include <linux/pagemap.h>
37 #include <linux/pagevec.h>
38 #include <linux/shmem_fs.h>
39 #include <linux/slab.h>
40 #include <linux/string_helpers.h>
41 #include <linux/types.h>
42 #include <linux/uaccess.h>
43 
44 #include <drm/drm.h>
45 #include <drm/drm_device.h>
46 #include <drm/drm_drv.h>
47 #include <drm/drm_file.h>
48 #include <drm/drm_gem.h>
49 #include <drm/drm_managed.h>
50 #include <drm/drm_print.h>
51 #include <drm/drm_vma_manager.h>
52 
53 #include "drm_internal.h"
54 
55 /** @file drm_gem.c
56  *
57  * This file provides some of the base ioctls and library routines for
58  * the graphics memory manager implemented by each device driver.
59  *
60  * Because various devices have different requirements in terms of
61  * synchronization and migration strategies, implementing that is left up to
62  * the driver, and all that the general API provides should be generic --
63  * allocating objects, reading/writing data with the cpu, freeing objects.
64  * Even there, platform-dependent optimizations for reading/writing data with
65  * the CPU mean we'll likely hook those out to driver-specific calls.  However,
66  * the DRI2 implementation wants to have at least allocate/mmap be generic.
67  *
68  * The goal was to have swap-backed object allocation managed through
69  * struct file.  However, file descriptors as handles to a struct file have
70  * two major failings:
71  * - Process limits prevent more than 1024 or so being used at a time by
72  *   default.
73  * - Inability to allocate high fds will aggravate the X Server's select()
74  *   handling, and likely that of many GL client applications as well.
75  *
76  * This led to a plan of using our own integer IDs (called handles, following
77  * DRM terminology) to mimic fds, and implement the fd syscalls we need as
78  * ioctls.  The objects themselves will still include the struct file so
79  * that we can transition to fds if the required kernel infrastructure shows
80  * up at a later date, and as our interface with shmfs for memory allocation.
81  */
82 
83 static void
drm_gem_init_release(struct drm_device * dev,void * ptr)84 drm_gem_init_release(struct drm_device *dev, void *ptr)
85 {
86 	drm_vma_offset_manager_destroy(dev->vma_offset_manager);
87 }
88 
89 /**
90  * drm_gem_init - Initialize the GEM device fields
91  * @dev: drm_devic structure to initialize
92  */
93 int
drm_gem_init(struct drm_device * dev)94 drm_gem_init(struct drm_device *dev)
95 {
96 	struct drm_vma_offset_manager *vma_offset_manager;
97 
98 	mutex_init(&dev->object_name_lock);
99 	idr_init_base(&dev->object_name_idr, 1);
100 
101 	vma_offset_manager = drmm_kzalloc(dev, sizeof(*vma_offset_manager),
102 					  GFP_KERNEL);
103 	if (!vma_offset_manager) {
104 		DRM_ERROR("out of memory\n");
105 		return -ENOMEM;
106 	}
107 
108 	dev->vma_offset_manager = vma_offset_manager;
109 	drm_vma_offset_manager_init(vma_offset_manager,
110 				    DRM_FILE_PAGE_OFFSET_START,
111 				    DRM_FILE_PAGE_OFFSET_SIZE);
112 
113 	return drmm_add_action(dev, drm_gem_init_release, NULL);
114 }
115 
116 /**
117  * drm_gem_object_init - initialize an allocated shmem-backed GEM object
118  * @dev: drm_device the object should be initialized for
119  * @obj: drm_gem_object to initialize
120  * @size: object size
121  *
122  * Initialize an already allocated GEM object of the specified size with
123  * shmfs backing store.
124  */
drm_gem_object_init(struct drm_device * dev,struct drm_gem_object * obj,size_t size)125 int drm_gem_object_init(struct drm_device *dev,
126 			struct drm_gem_object *obj, size_t size)
127 {
128 	struct file *filp;
129 
130 	drm_gem_private_object_init(dev, obj, size);
131 
132 	filp = shmem_file_setup("drm mm object", size, VM_NORESERVE);
133 	if (IS_ERR(filp))
134 		return PTR_ERR(filp);
135 
136 	obj->filp = filp;
137 
138 	return 0;
139 }
140 EXPORT_SYMBOL(drm_gem_object_init);
141 
142 /**
143  * drm_gem_private_object_init - initialize an allocated private GEM object
144  * @dev: drm_device the object should be initialized for
145  * @obj: drm_gem_object to initialize
146  * @size: object size
147  *
148  * Initialize an already allocated GEM object of the specified size with
149  * no GEM provided backing store. Instead the caller is responsible for
150  * backing the object and handling it.
151  */
drm_gem_private_object_init(struct drm_device * dev,struct drm_gem_object * obj,size_t size)152 void drm_gem_private_object_init(struct drm_device *dev,
153 				 struct drm_gem_object *obj, size_t size)
154 {
155 	BUG_ON((size & (PAGE_SIZE - 1)) != 0);
156 
157 	obj->dev = dev;
158 	obj->filp = NULL;
159 
160 	kref_init(&obj->refcount);
161 	obj->handle_count = 0;
162 	obj->size = size;
163 	dma_resv_init(&obj->_resv);
164 	if (!obj->resv)
165 		obj->resv = &obj->_resv;
166 
167 	if (drm_core_check_feature(dev, DRIVER_GEM_GPUVA))
168 		drm_gem_gpuva_init(obj);
169 
170 	drm_vma_node_reset(&obj->vma_node);
171 	INIT_LIST_HEAD(&obj->lru_node);
172 }
173 EXPORT_SYMBOL(drm_gem_private_object_init);
174 
175 /**
176  * drm_gem_private_object_fini - Finalize a failed drm_gem_object
177  * @obj: drm_gem_object
178  *
179  * Uninitialize an already allocated GEM object when it initialized failed
180  */
drm_gem_private_object_fini(struct drm_gem_object * obj)181 void drm_gem_private_object_fini(struct drm_gem_object *obj)
182 {
183 	WARN_ON(obj->dma_buf);
184 
185 	dma_resv_fini(&obj->_resv);
186 }
187 EXPORT_SYMBOL(drm_gem_private_object_fini);
188 
189 /**
190  * drm_gem_object_handle_free - release resources bound to userspace handles
191  * @obj: GEM object to clean up.
192  *
193  * Called after the last handle to the object has been closed
194  *
195  * Removes any name for the object. Note that this must be
196  * called before drm_gem_object_free or we'll be touching
197  * freed memory
198  */
drm_gem_object_handle_free(struct drm_gem_object * obj)199 static void drm_gem_object_handle_free(struct drm_gem_object *obj)
200 {
201 	struct drm_device *dev = obj->dev;
202 
203 	/* Remove any name for this object */
204 	if (obj->name) {
205 		idr_remove(&dev->object_name_idr, obj->name);
206 		obj->name = 0;
207 	}
208 }
209 
drm_gem_object_exported_dma_buf_free(struct drm_gem_object * obj)210 static void drm_gem_object_exported_dma_buf_free(struct drm_gem_object *obj)
211 {
212 	/* Unbreak the reference cycle if we have an exported dma_buf. */
213 	if (obj->dma_buf) {
214 		dma_buf_put(obj->dma_buf);
215 		obj->dma_buf = NULL;
216 	}
217 }
218 
219 static void
drm_gem_object_handle_put_unlocked(struct drm_gem_object * obj)220 drm_gem_object_handle_put_unlocked(struct drm_gem_object *obj)
221 {
222 	struct drm_device *dev = obj->dev;
223 	bool final = false;
224 
225 	if (WARN_ON(READ_ONCE(obj->handle_count) == 0))
226 		return;
227 
228 	/*
229 	* Must bump handle count first as this may be the last
230 	* ref, in which case the object would disappear before we
231 	* checked for a name
232 	*/
233 
234 	mutex_lock(&dev->object_name_lock);
235 	if (--obj->handle_count == 0) {
236 		drm_gem_object_handle_free(obj);
237 		drm_gem_object_exported_dma_buf_free(obj);
238 		final = true;
239 	}
240 	mutex_unlock(&dev->object_name_lock);
241 
242 	if (final)
243 		drm_gem_object_put(obj);
244 }
245 
246 /*
247  * Called at device or object close to release the file's
248  * handle references on objects.
249  */
250 static int
drm_gem_object_release_handle(int id,void * ptr,void * data)251 drm_gem_object_release_handle(int id, void *ptr, void *data)
252 {
253 	struct drm_file *file_priv = data;
254 	struct drm_gem_object *obj = ptr;
255 
256 	if (obj->funcs->close)
257 		obj->funcs->close(obj, file_priv);
258 
259 	drm_prime_remove_buf_handle(&file_priv->prime, id);
260 	drm_vma_node_revoke(&obj->vma_node, file_priv);
261 
262 	drm_gem_object_handle_put_unlocked(obj);
263 
264 	return 0;
265 }
266 
267 /**
268  * drm_gem_handle_delete - deletes the given file-private handle
269  * @filp: drm file-private structure to use for the handle look up
270  * @handle: userspace handle to delete
271  *
272  * Removes the GEM handle from the @filp lookup table which has been added with
273  * drm_gem_handle_create(). If this is the last handle also cleans up linked
274  * resources like GEM names.
275  */
276 int
drm_gem_handle_delete(struct drm_file * filp,u32 handle)277 drm_gem_handle_delete(struct drm_file *filp, u32 handle)
278 {
279 	struct drm_gem_object *obj;
280 
281 	spin_lock(&filp->table_lock);
282 
283 	/* Check if we currently have a reference on the object */
284 	obj = idr_replace(&filp->object_idr, NULL, handle);
285 	spin_unlock(&filp->table_lock);
286 	if (IS_ERR_OR_NULL(obj))
287 		return -EINVAL;
288 
289 	/* Release driver's reference and decrement refcount. */
290 	drm_gem_object_release_handle(handle, obj, filp);
291 
292 	/* And finally make the handle available for future allocations. */
293 	spin_lock(&filp->table_lock);
294 	idr_remove(&filp->object_idr, handle);
295 	spin_unlock(&filp->table_lock);
296 
297 	return 0;
298 }
299 EXPORT_SYMBOL(drm_gem_handle_delete);
300 
301 /**
302  * drm_gem_dumb_map_offset - return the fake mmap offset for a gem object
303  * @file: drm file-private structure containing the gem object
304  * @dev: corresponding drm_device
305  * @handle: gem object handle
306  * @offset: return location for the fake mmap offset
307  *
308  * This implements the &drm_driver.dumb_map_offset kms driver callback for
309  * drivers which use gem to manage their backing storage.
310  *
311  * Returns:
312  * 0 on success or a negative error code on failure.
313  */
drm_gem_dumb_map_offset(struct drm_file * file,struct drm_device * dev,u32 handle,u64 * offset)314 int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev,
315 			    u32 handle, u64 *offset)
316 {
317 	struct drm_gem_object *obj;
318 	int ret;
319 
320 	obj = drm_gem_object_lookup(file, handle);
321 	if (!obj)
322 		return -ENOENT;
323 
324 	/* Don't allow imported objects to be mapped */
325 	if (obj->import_attach) {
326 		ret = -EINVAL;
327 		goto out;
328 	}
329 
330 	ret = drm_gem_create_mmap_offset(obj);
331 	if (ret)
332 		goto out;
333 
334 	*offset = drm_vma_node_offset_addr(&obj->vma_node);
335 out:
336 	drm_gem_object_put(obj);
337 
338 	return ret;
339 }
340 EXPORT_SYMBOL_GPL(drm_gem_dumb_map_offset);
341 
342 /**
343  * drm_gem_handle_create_tail - internal functions to create a handle
344  * @file_priv: drm file-private structure to register the handle for
345  * @obj: object to register
346  * @handlep: pointer to return the created handle to the caller
347  *
348  * This expects the &drm_device.object_name_lock to be held already and will
349  * drop it before returning. Used to avoid races in establishing new handles
350  * when importing an object from either an flink name or a dma-buf.
351  *
352  * Handles must be release again through drm_gem_handle_delete(). This is done
353  * when userspace closes @file_priv for all attached handles, or through the
354  * GEM_CLOSE ioctl for individual handles.
355  */
356 int
drm_gem_handle_create_tail(struct drm_file * file_priv,struct drm_gem_object * obj,u32 * handlep)357 drm_gem_handle_create_tail(struct drm_file *file_priv,
358 			   struct drm_gem_object *obj,
359 			   u32 *handlep)
360 {
361 	struct drm_device *dev = obj->dev;
362 	u32 handle;
363 	int ret;
364 
365 	WARN_ON(!mutex_is_locked(&dev->object_name_lock));
366 	if (obj->handle_count++ == 0)
367 		drm_gem_object_get(obj);
368 
369 	/*
370 	 * Get the user-visible handle using idr.  Preload and perform
371 	 * allocation under our spinlock.
372 	 */
373 	idr_preload(GFP_KERNEL);
374 	spin_lock(&file_priv->table_lock);
375 
376 	ret = idr_alloc(&file_priv->object_idr, obj, 1, 0, GFP_NOWAIT);
377 
378 	spin_unlock(&file_priv->table_lock);
379 	idr_preload_end();
380 
381 	mutex_unlock(&dev->object_name_lock);
382 	if (ret < 0)
383 		goto err_unref;
384 
385 	handle = ret;
386 
387 	ret = drm_vma_node_allow(&obj->vma_node, file_priv);
388 	if (ret)
389 		goto err_remove;
390 
391 	if (obj->funcs->open) {
392 		ret = obj->funcs->open(obj, file_priv);
393 		if (ret)
394 			goto err_revoke;
395 	}
396 
397 	*handlep = handle;
398 	return 0;
399 
400 err_revoke:
401 	drm_vma_node_revoke(&obj->vma_node, file_priv);
402 err_remove:
403 	spin_lock(&file_priv->table_lock);
404 	idr_remove(&file_priv->object_idr, handle);
405 	spin_unlock(&file_priv->table_lock);
406 err_unref:
407 	drm_gem_object_handle_put_unlocked(obj);
408 	return ret;
409 }
410 
411 /**
412  * drm_gem_handle_create - create a gem handle for an object
413  * @file_priv: drm file-private structure to register the handle for
414  * @obj: object to register
415  * @handlep: pointer to return the created handle to the caller
416  *
417  * Create a handle for this object. This adds a handle reference to the object,
418  * which includes a regular reference count. Callers will likely want to
419  * dereference the object afterwards.
420  *
421  * Since this publishes @obj to userspace it must be fully set up by this point,
422  * drivers must call this last in their buffer object creation callbacks.
423  */
drm_gem_handle_create(struct drm_file * file_priv,struct drm_gem_object * obj,u32 * handlep)424 int drm_gem_handle_create(struct drm_file *file_priv,
425 			  struct drm_gem_object *obj,
426 			  u32 *handlep)
427 {
428 	mutex_lock(&obj->dev->object_name_lock);
429 
430 	return drm_gem_handle_create_tail(file_priv, obj, handlep);
431 }
432 EXPORT_SYMBOL(drm_gem_handle_create);
433 
434 
435 /**
436  * drm_gem_free_mmap_offset - release a fake mmap offset for an object
437  * @obj: obj in question
438  *
439  * This routine frees fake offsets allocated by drm_gem_create_mmap_offset().
440  *
441  * Note that drm_gem_object_release() already calls this function, so drivers
442  * don't have to take care of releasing the mmap offset themselves when freeing
443  * the GEM object.
444  */
445 void
drm_gem_free_mmap_offset(struct drm_gem_object * obj)446 drm_gem_free_mmap_offset(struct drm_gem_object *obj)
447 {
448 	struct drm_device *dev = obj->dev;
449 
450 	drm_vma_offset_remove(dev->vma_offset_manager, &obj->vma_node);
451 }
452 EXPORT_SYMBOL(drm_gem_free_mmap_offset);
453 
454 /**
455  * drm_gem_create_mmap_offset_size - create a fake mmap offset for an object
456  * @obj: obj in question
457  * @size: the virtual size
458  *
459  * GEM memory mapping works by handing back to userspace a fake mmap offset
460  * it can use in a subsequent mmap(2) call.  The DRM core code then looks
461  * up the object based on the offset and sets up the various memory mapping
462  * structures.
463  *
464  * This routine allocates and attaches a fake offset for @obj, in cases where
465  * the virtual size differs from the physical size (ie. &drm_gem_object.size).
466  * Otherwise just use drm_gem_create_mmap_offset().
467  *
468  * This function is idempotent and handles an already allocated mmap offset
469  * transparently. Drivers do not need to check for this case.
470  */
471 int
drm_gem_create_mmap_offset_size(struct drm_gem_object * obj,size_t size)472 drm_gem_create_mmap_offset_size(struct drm_gem_object *obj, size_t size)
473 {
474 	struct drm_device *dev = obj->dev;
475 
476 	return drm_vma_offset_add(dev->vma_offset_manager, &obj->vma_node,
477 				  size / PAGE_SIZE);
478 }
479 EXPORT_SYMBOL(drm_gem_create_mmap_offset_size);
480 
481 /**
482  * drm_gem_create_mmap_offset - create a fake mmap offset for an object
483  * @obj: obj in question
484  *
485  * GEM memory mapping works by handing back to userspace a fake mmap offset
486  * it can use in a subsequent mmap(2) call.  The DRM core code then looks
487  * up the object based on the offset and sets up the various memory mapping
488  * structures.
489  *
490  * This routine allocates and attaches a fake offset for @obj.
491  *
492  * Drivers can call drm_gem_free_mmap_offset() before freeing @obj to release
493  * the fake offset again.
494  */
drm_gem_create_mmap_offset(struct drm_gem_object * obj)495 int drm_gem_create_mmap_offset(struct drm_gem_object *obj)
496 {
497 	return drm_gem_create_mmap_offset_size(obj, obj->size);
498 }
499 EXPORT_SYMBOL(drm_gem_create_mmap_offset);
500 
501 /*
502  * Move folios to appropriate lru and release the folios, decrementing the
503  * ref count of those folios.
504  */
drm_gem_check_release_batch(struct folio_batch * fbatch)505 static void drm_gem_check_release_batch(struct folio_batch *fbatch)
506 {
507 	check_move_unevictable_folios(fbatch);
508 	__folio_batch_release(fbatch);
509 	cond_resched();
510 }
511 
512 /**
513  * drm_gem_get_pages - helper to allocate backing pages for a GEM object
514  * from shmem
515  * @obj: obj in question
516  *
517  * This reads the page-array of the shmem-backing storage of the given gem
518  * object. An array of pages is returned. If a page is not allocated or
519  * swapped-out, this will allocate/swap-in the required pages. Note that the
520  * whole object is covered by the page-array and pinned in memory.
521  *
522  * Use drm_gem_put_pages() to release the array and unpin all pages.
523  *
524  * This uses the GFP-mask set on the shmem-mapping (see mapping_set_gfp_mask()).
525  * If you require other GFP-masks, you have to do those allocations yourself.
526  *
527  * Note that you are not allowed to change gfp-zones during runtime. That is,
528  * shmem_read_mapping_page_gfp() must be called with the same gfp_zone(gfp) as
529  * set during initialization. If you have special zone constraints, set them
530  * after drm_gem_object_init() via mapping_set_gfp_mask(). shmem-core takes care
531  * to keep pages in the required zone during swap-in.
532  *
533  * This function is only valid on objects initialized with
534  * drm_gem_object_init(), but not for those initialized with
535  * drm_gem_private_object_init() only.
536  */
drm_gem_get_pages(struct drm_gem_object * obj)537 struct page **drm_gem_get_pages(struct drm_gem_object *obj)
538 {
539 	struct address_space *mapping;
540 	struct page **pages;
541 	struct folio *folio;
542 	struct folio_batch fbatch;
543 	long i, j, npages;
544 
545 	if (WARN_ON(!obj->filp))
546 		return ERR_PTR(-EINVAL);
547 
548 	/* This is the shared memory object that backs the GEM resource */
549 	mapping = obj->filp->f_mapping;
550 
551 	/* We already BUG_ON() for non-page-aligned sizes in
552 	 * drm_gem_object_init(), so we should never hit this unless
553 	 * driver author is doing something really wrong:
554 	 */
555 	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
556 
557 	npages = obj->size >> PAGE_SHIFT;
558 
559 	pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
560 	if (pages == NULL)
561 		return ERR_PTR(-ENOMEM);
562 
563 	mapping_set_unevictable(mapping);
564 
565 	i = 0;
566 	while (i < npages) {
567 		long nr;
568 		folio = shmem_read_folio_gfp(mapping, i,
569 				mapping_gfp_mask(mapping));
570 		if (IS_ERR(folio))
571 			goto fail;
572 		nr = min(npages - i, folio_nr_pages(folio));
573 		for (j = 0; j < nr; j++, i++)
574 			pages[i] = folio_file_page(folio, i);
575 
576 		/* Make sure shmem keeps __GFP_DMA32 allocated pages in the
577 		 * correct region during swapin. Note that this requires
578 		 * __GFP_DMA32 to be set in mapping_gfp_mask(inode->i_mapping)
579 		 * so shmem can relocate pages during swapin if required.
580 		 */
581 		BUG_ON(mapping_gfp_constraint(mapping, __GFP_DMA32) &&
582 				(folio_pfn(folio) >= 0x00100000UL));
583 	}
584 
585 	return pages;
586 
587 fail:
588 	mapping_clear_unevictable(mapping);
589 	folio_batch_init(&fbatch);
590 	j = 0;
591 	while (j < i) {
592 		struct folio *f = page_folio(pages[j]);
593 		if (!folio_batch_add(&fbatch, f))
594 			drm_gem_check_release_batch(&fbatch);
595 		j += folio_nr_pages(f);
596 	}
597 	if (fbatch.nr)
598 		drm_gem_check_release_batch(&fbatch);
599 
600 	kvfree(pages);
601 	return ERR_CAST(folio);
602 }
603 EXPORT_SYMBOL(drm_gem_get_pages);
604 
605 /**
606  * drm_gem_put_pages - helper to free backing pages for a GEM object
607  * @obj: obj in question
608  * @pages: pages to free
609  * @dirty: if true, pages will be marked as dirty
610  * @accessed: if true, the pages will be marked as accessed
611  */
drm_gem_put_pages(struct drm_gem_object * obj,struct page ** pages,bool dirty,bool accessed)612 void drm_gem_put_pages(struct drm_gem_object *obj, struct page **pages,
613 		bool dirty, bool accessed)
614 {
615 	int i, npages;
616 	struct address_space *mapping;
617 	struct folio_batch fbatch;
618 
619 	mapping = file_inode(obj->filp)->i_mapping;
620 	mapping_clear_unevictable(mapping);
621 
622 	/* We already BUG_ON() for non-page-aligned sizes in
623 	 * drm_gem_object_init(), so we should never hit this unless
624 	 * driver author is doing something really wrong:
625 	 */
626 	WARN_ON((obj->size & (PAGE_SIZE - 1)) != 0);
627 
628 	npages = obj->size >> PAGE_SHIFT;
629 
630 	folio_batch_init(&fbatch);
631 	for (i = 0; i < npages; i++) {
632 		struct folio *folio;
633 
634 		if (!pages[i])
635 			continue;
636 		folio = page_folio(pages[i]);
637 
638 		if (dirty)
639 			folio_mark_dirty(folio);
640 
641 		if (accessed)
642 			folio_mark_accessed(folio);
643 
644 		/* Undo the reference we took when populating the table */
645 		if (!folio_batch_add(&fbatch, folio))
646 			drm_gem_check_release_batch(&fbatch);
647 		i += folio_nr_pages(folio) - 1;
648 	}
649 	if (folio_batch_count(&fbatch))
650 		drm_gem_check_release_batch(&fbatch);
651 
652 	kvfree(pages);
653 }
654 EXPORT_SYMBOL(drm_gem_put_pages);
655 
objects_lookup(struct drm_file * filp,u32 * handle,int count,struct drm_gem_object ** objs)656 static int objects_lookup(struct drm_file *filp, u32 *handle, int count,
657 			  struct drm_gem_object **objs)
658 {
659 	int i, ret = 0;
660 	struct drm_gem_object *obj;
661 
662 	spin_lock(&filp->table_lock);
663 
664 	for (i = 0; i < count; i++) {
665 		/* Check if we currently have a reference on the object */
666 		obj = idr_find(&filp->object_idr, handle[i]);
667 		if (!obj) {
668 			ret = -ENOENT;
669 			break;
670 		}
671 		drm_gem_object_get(obj);
672 		objs[i] = obj;
673 	}
674 	spin_unlock(&filp->table_lock);
675 
676 	return ret;
677 }
678 
679 /**
680  * drm_gem_objects_lookup - look up GEM objects from an array of handles
681  * @filp: DRM file private date
682  * @bo_handles: user pointer to array of userspace handle
683  * @count: size of handle array
684  * @objs_out: returned pointer to array of drm_gem_object pointers
685  *
686  * Takes an array of userspace handles and returns a newly allocated array of
687  * GEM objects.
688  *
689  * For a single handle lookup, use drm_gem_object_lookup().
690  *
691  * Returns:
692  *
693  * @objs filled in with GEM object pointers. Returned GEM objects need to be
694  * released with drm_gem_object_put(). -ENOENT is returned on a lookup
695  * failure. 0 is returned on success.
696  *
697  */
drm_gem_objects_lookup(struct drm_file * filp,void __user * bo_handles,int count,struct drm_gem_object *** objs_out)698 int drm_gem_objects_lookup(struct drm_file *filp, void __user *bo_handles,
699 			   int count, struct drm_gem_object ***objs_out)
700 {
701 	int ret;
702 	u32 *handles;
703 	struct drm_gem_object **objs;
704 
705 	if (!count)
706 		return 0;
707 
708 	objs = kvmalloc_array(count, sizeof(struct drm_gem_object *),
709 			     GFP_KERNEL | __GFP_ZERO);
710 	if (!objs)
711 		return -ENOMEM;
712 
713 	*objs_out = objs;
714 
715 	handles = kvmalloc_array(count, sizeof(u32), GFP_KERNEL);
716 	if (!handles) {
717 		ret = -ENOMEM;
718 		goto out;
719 	}
720 
721 	if (copy_from_user(handles, bo_handles, count * sizeof(u32))) {
722 		ret = -EFAULT;
723 		DRM_DEBUG("Failed to copy in GEM handles\n");
724 		goto out;
725 	}
726 
727 	ret = objects_lookup(filp, handles, count, objs);
728 out:
729 	kvfree(handles);
730 	return ret;
731 
732 }
733 EXPORT_SYMBOL(drm_gem_objects_lookup);
734 
735 /**
736  * drm_gem_object_lookup - look up a GEM object from its handle
737  * @filp: DRM file private date
738  * @handle: userspace handle
739  *
740  * Returns:
741  *
742  * A reference to the object named by the handle if such exists on @filp, NULL
743  * otherwise.
744  *
745  * If looking up an array of handles, use drm_gem_objects_lookup().
746  */
747 struct drm_gem_object *
drm_gem_object_lookup(struct drm_file * filp,u32 handle)748 drm_gem_object_lookup(struct drm_file *filp, u32 handle)
749 {
750 	struct drm_gem_object *obj = NULL;
751 
752 	objects_lookup(filp, &handle, 1, &obj);
753 	return obj;
754 }
755 EXPORT_SYMBOL(drm_gem_object_lookup);
756 
757 /**
758  * drm_gem_dma_resv_wait - Wait on GEM object's reservation's objects
759  * shared and/or exclusive fences.
760  * @filep: DRM file private date
761  * @handle: userspace handle
762  * @wait_all: if true, wait on all fences, else wait on just exclusive fence
763  * @timeout: timeout value in jiffies or zero to return immediately
764  *
765  * Returns:
766  *
767  * Returns -ERESTARTSYS if interrupted, 0 if the wait timed out, or
768  * greater than 0 on success.
769  */
drm_gem_dma_resv_wait(struct drm_file * filep,u32 handle,bool wait_all,unsigned long timeout)770 long drm_gem_dma_resv_wait(struct drm_file *filep, u32 handle,
771 				    bool wait_all, unsigned long timeout)
772 {
773 	long ret;
774 	struct drm_gem_object *obj;
775 
776 	obj = drm_gem_object_lookup(filep, handle);
777 	if (!obj) {
778 		DRM_DEBUG("Failed to look up GEM BO %d\n", handle);
779 		return -EINVAL;
780 	}
781 
782 	ret = dma_resv_wait_timeout(obj->resv, dma_resv_usage_rw(wait_all),
783 				    true, timeout);
784 	if (ret == 0)
785 		ret = -ETIME;
786 	else if (ret > 0)
787 		ret = 0;
788 
789 	drm_gem_object_put(obj);
790 
791 	return ret;
792 }
793 EXPORT_SYMBOL(drm_gem_dma_resv_wait);
794 
795 /**
796  * drm_gem_close_ioctl - implementation of the GEM_CLOSE ioctl
797  * @dev: drm_device
798  * @data: ioctl data
799  * @file_priv: drm file-private structure
800  *
801  * Releases the handle to an mm object.
802  */
803 int
drm_gem_close_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)804 drm_gem_close_ioctl(struct drm_device *dev, void *data,
805 		    struct drm_file *file_priv)
806 {
807 	struct drm_gem_close *args = data;
808 	int ret;
809 
810 	if (!drm_core_check_feature(dev, DRIVER_GEM))
811 		return -EOPNOTSUPP;
812 
813 	ret = drm_gem_handle_delete(file_priv, args->handle);
814 
815 	return ret;
816 }
817 
818 /**
819  * drm_gem_flink_ioctl - implementation of the GEM_FLINK ioctl
820  * @dev: drm_device
821  * @data: ioctl data
822  * @file_priv: drm file-private structure
823  *
824  * Create a global name for an object, returning the name.
825  *
826  * Note that the name does not hold a reference; when the object
827  * is freed, the name goes away.
828  */
829 int
drm_gem_flink_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)830 drm_gem_flink_ioctl(struct drm_device *dev, void *data,
831 		    struct drm_file *file_priv)
832 {
833 	struct drm_gem_flink *args = data;
834 	struct drm_gem_object *obj;
835 	int ret;
836 
837 	if (!drm_core_check_feature(dev, DRIVER_GEM))
838 		return -EOPNOTSUPP;
839 
840 	obj = drm_gem_object_lookup(file_priv, args->handle);
841 	if (obj == NULL)
842 		return -ENOENT;
843 
844 	mutex_lock(&dev->object_name_lock);
845 	/* prevent races with concurrent gem_close. */
846 	if (obj->handle_count == 0) {
847 		ret = -ENOENT;
848 		goto err;
849 	}
850 
851 	if (!obj->name) {
852 		ret = idr_alloc(&dev->object_name_idr, obj, 1, 0, GFP_KERNEL);
853 		if (ret < 0)
854 			goto err;
855 
856 		obj->name = ret;
857 	}
858 
859 	args->name = (uint64_t) obj->name;
860 	ret = 0;
861 
862 err:
863 	mutex_unlock(&dev->object_name_lock);
864 	drm_gem_object_put(obj);
865 	return ret;
866 }
867 
868 /**
869  * drm_gem_open_ioctl - implementation of the GEM_OPEN ioctl
870  * @dev: drm_device
871  * @data: ioctl data
872  * @file_priv: drm file-private structure
873  *
874  * Open an object using the global name, returning a handle and the size.
875  *
876  * This handle (of course) holds a reference to the object, so the object
877  * will not go away until the handle is deleted.
878  */
879 int
drm_gem_open_ioctl(struct drm_device * dev,void * data,struct drm_file * file_priv)880 drm_gem_open_ioctl(struct drm_device *dev, void *data,
881 		   struct drm_file *file_priv)
882 {
883 	struct drm_gem_open *args = data;
884 	struct drm_gem_object *obj;
885 	int ret;
886 	u32 handle;
887 
888 	if (!drm_core_check_feature(dev, DRIVER_GEM))
889 		return -EOPNOTSUPP;
890 
891 	mutex_lock(&dev->object_name_lock);
892 	obj = idr_find(&dev->object_name_idr, (int) args->name);
893 	if (obj) {
894 		drm_gem_object_get(obj);
895 	} else {
896 		mutex_unlock(&dev->object_name_lock);
897 		return -ENOENT;
898 	}
899 
900 	/* drm_gem_handle_create_tail unlocks dev->object_name_lock. */
901 	ret = drm_gem_handle_create_tail(file_priv, obj, &handle);
902 	if (ret)
903 		goto err;
904 
905 	args->handle = handle;
906 	args->size = obj->size;
907 
908 err:
909 	drm_gem_object_put(obj);
910 	return ret;
911 }
912 
913 /**
914  * drm_gem_open - initializes GEM file-private structures at devnode open time
915  * @dev: drm_device which is being opened by userspace
916  * @file_private: drm file-private structure to set up
917  *
918  * Called at device open time, sets up the structure for handling refcounting
919  * of mm objects.
920  */
921 void
drm_gem_open(struct drm_device * dev,struct drm_file * file_private)922 drm_gem_open(struct drm_device *dev, struct drm_file *file_private)
923 {
924 	idr_init_base(&file_private->object_idr, 1);
925 	spin_lock_init(&file_private->table_lock);
926 }
927 
928 /**
929  * drm_gem_release - release file-private GEM resources
930  * @dev: drm_device which is being closed by userspace
931  * @file_private: drm file-private structure to clean up
932  *
933  * Called at close time when the filp is going away.
934  *
935  * Releases any remaining references on objects by this filp.
936  */
937 void
drm_gem_release(struct drm_device * dev,struct drm_file * file_private)938 drm_gem_release(struct drm_device *dev, struct drm_file *file_private)
939 {
940 	idr_for_each(&file_private->object_idr,
941 		     &drm_gem_object_release_handle, file_private);
942 	idr_destroy(&file_private->object_idr);
943 }
944 
945 /**
946  * drm_gem_object_release - release GEM buffer object resources
947  * @obj: GEM buffer object
948  *
949  * This releases any structures and resources used by @obj and is the inverse of
950  * drm_gem_object_init().
951  */
952 void
drm_gem_object_release(struct drm_gem_object * obj)953 drm_gem_object_release(struct drm_gem_object *obj)
954 {
955 	if (obj->filp)
956 		fput(obj->filp);
957 
958 	drm_gem_private_object_fini(obj);
959 
960 	drm_gem_free_mmap_offset(obj);
961 	drm_gem_lru_remove(obj);
962 }
963 EXPORT_SYMBOL(drm_gem_object_release);
964 
965 /**
966  * drm_gem_object_free - free a GEM object
967  * @kref: kref of the object to free
968  *
969  * Called after the last reference to the object has been lost.
970  *
971  * Frees the object
972  */
973 void
drm_gem_object_free(struct kref * kref)974 drm_gem_object_free(struct kref *kref)
975 {
976 	struct drm_gem_object *obj =
977 		container_of(kref, struct drm_gem_object, refcount);
978 
979 	if (WARN_ON(!obj->funcs->free))
980 		return;
981 
982 	obj->funcs->free(obj);
983 }
984 EXPORT_SYMBOL(drm_gem_object_free);
985 
986 /**
987  * drm_gem_vm_open - vma->ops->open implementation for GEM
988  * @vma: VM area structure
989  *
990  * This function implements the #vm_operations_struct open() callback for GEM
991  * drivers. This must be used together with drm_gem_vm_close().
992  */
drm_gem_vm_open(struct vm_area_struct * vma)993 void drm_gem_vm_open(struct vm_area_struct *vma)
994 {
995 	struct drm_gem_object *obj = vma->vm_private_data;
996 
997 	drm_gem_object_get(obj);
998 }
999 EXPORT_SYMBOL(drm_gem_vm_open);
1000 
1001 /**
1002  * drm_gem_vm_close - vma->ops->close implementation for GEM
1003  * @vma: VM area structure
1004  *
1005  * This function implements the #vm_operations_struct close() callback for GEM
1006  * drivers. This must be used together with drm_gem_vm_open().
1007  */
drm_gem_vm_close(struct vm_area_struct * vma)1008 void drm_gem_vm_close(struct vm_area_struct *vma)
1009 {
1010 	struct drm_gem_object *obj = vma->vm_private_data;
1011 
1012 	drm_gem_object_put(obj);
1013 }
1014 EXPORT_SYMBOL(drm_gem_vm_close);
1015 
1016 /**
1017  * drm_gem_mmap_obj - memory map a GEM object
1018  * @obj: the GEM object to map
1019  * @obj_size: the object size to be mapped, in bytes
1020  * @vma: VMA for the area to be mapped
1021  *
1022  * Set up the VMA to prepare mapping of the GEM object using the GEM object's
1023  * vm_ops. Depending on their requirements, GEM objects can either
1024  * provide a fault handler in their vm_ops (in which case any accesses to
1025  * the object will be trapped, to perform migration, GTT binding, surface
1026  * register allocation, or performance monitoring), or mmap the buffer memory
1027  * synchronously after calling drm_gem_mmap_obj.
1028  *
1029  * This function is mainly intended to implement the DMABUF mmap operation, when
1030  * the GEM object is not looked up based on its fake offset. To implement the
1031  * DRM mmap operation, drivers should use the drm_gem_mmap() function.
1032  *
1033  * drm_gem_mmap_obj() assumes the user is granted access to the buffer while
1034  * drm_gem_mmap() prevents unprivileged users from mapping random objects. So
1035  * callers must verify access restrictions before calling this helper.
1036  *
1037  * Return 0 or success or -EINVAL if the object size is smaller than the VMA
1038  * size, or if no vm_ops are provided.
1039  */
drm_gem_mmap_obj(struct drm_gem_object * obj,unsigned long obj_size,struct vm_area_struct * vma)1040 int drm_gem_mmap_obj(struct drm_gem_object *obj, unsigned long obj_size,
1041 		     struct vm_area_struct *vma)
1042 {
1043 	int ret;
1044 
1045 	/* Check for valid size. */
1046 	if (obj_size < vma->vm_end - vma->vm_start)
1047 		return -EINVAL;
1048 
1049 	/* Take a ref for this mapping of the object, so that the fault
1050 	 * handler can dereference the mmap offset's pointer to the object.
1051 	 * This reference is cleaned up by the corresponding vm_close
1052 	 * (which should happen whether the vma was created by this call, or
1053 	 * by a vm_open due to mremap or partial unmap or whatever).
1054 	 */
1055 	drm_gem_object_get(obj);
1056 
1057 	vma->vm_private_data = obj;
1058 	vma->vm_ops = obj->funcs->vm_ops;
1059 
1060 	if (obj->funcs->mmap) {
1061 		ret = obj->funcs->mmap(obj, vma);
1062 		if (ret)
1063 			goto err_drm_gem_object_put;
1064 		WARN_ON(!(vma->vm_flags & VM_DONTEXPAND));
1065 	} else {
1066 		if (!vma->vm_ops) {
1067 			ret = -EINVAL;
1068 			goto err_drm_gem_object_put;
1069 		}
1070 
1071 		vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
1072 		vma->vm_page_prot = pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
1073 		vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
1074 	}
1075 
1076 	return 0;
1077 
1078 err_drm_gem_object_put:
1079 	drm_gem_object_put(obj);
1080 	return ret;
1081 }
1082 EXPORT_SYMBOL(drm_gem_mmap_obj);
1083 
1084 /**
1085  * drm_gem_mmap - memory map routine for GEM objects
1086  * @filp: DRM file pointer
1087  * @vma: VMA for the area to be mapped
1088  *
1089  * If a driver supports GEM object mapping, mmap calls on the DRM file
1090  * descriptor will end up here.
1091  *
1092  * Look up the GEM object based on the offset passed in (vma->vm_pgoff will
1093  * contain the fake offset we created when the GTT map ioctl was called on
1094  * the object) and map it with a call to drm_gem_mmap_obj().
1095  *
1096  * If the caller is not granted access to the buffer object, the mmap will fail
1097  * with EACCES. Please see the vma manager for more information.
1098  */
drm_gem_mmap(struct file * filp,struct vm_area_struct * vma)1099 int drm_gem_mmap(struct file *filp, struct vm_area_struct *vma)
1100 {
1101 	struct drm_file *priv = filp->private_data;
1102 	struct drm_device *dev = priv->minor->dev;
1103 	struct drm_gem_object *obj = NULL;
1104 	struct drm_vma_offset_node *node;
1105 	int ret;
1106 
1107 	if (drm_dev_is_unplugged(dev))
1108 		return -ENODEV;
1109 
1110 	drm_vma_offset_lock_lookup(dev->vma_offset_manager);
1111 	node = drm_vma_offset_exact_lookup_locked(dev->vma_offset_manager,
1112 						  vma->vm_pgoff,
1113 						  vma_pages(vma));
1114 	if (likely(node)) {
1115 		obj = container_of(node, struct drm_gem_object, vma_node);
1116 		/*
1117 		 * When the object is being freed, after it hits 0-refcnt it
1118 		 * proceeds to tear down the object. In the process it will
1119 		 * attempt to remove the VMA offset and so acquire this
1120 		 * mgr->vm_lock.  Therefore if we find an object with a 0-refcnt
1121 		 * that matches our range, we know it is in the process of being
1122 		 * destroyed and will be freed as soon as we release the lock -
1123 		 * so we have to check for the 0-refcnted object and treat it as
1124 		 * invalid.
1125 		 */
1126 		if (!kref_get_unless_zero(&obj->refcount))
1127 			obj = NULL;
1128 	}
1129 	drm_vma_offset_unlock_lookup(dev->vma_offset_manager);
1130 
1131 	if (!obj)
1132 		return -EINVAL;
1133 
1134 	if (!drm_vma_node_is_allowed(node, priv)) {
1135 		drm_gem_object_put(obj);
1136 		return -EACCES;
1137 	}
1138 
1139 	ret = drm_gem_mmap_obj(obj, drm_vma_node_size(node) << PAGE_SHIFT,
1140 			       vma);
1141 
1142 	drm_gem_object_put(obj);
1143 
1144 	return ret;
1145 }
1146 EXPORT_SYMBOL(drm_gem_mmap);
1147 
drm_gem_print_info(struct drm_printer * p,unsigned int indent,const struct drm_gem_object * obj)1148 void drm_gem_print_info(struct drm_printer *p, unsigned int indent,
1149 			const struct drm_gem_object *obj)
1150 {
1151 	drm_printf_indent(p, indent, "name=%d\n", obj->name);
1152 	drm_printf_indent(p, indent, "refcount=%u\n",
1153 			  kref_read(&obj->refcount));
1154 	drm_printf_indent(p, indent, "start=%08lx\n",
1155 			  drm_vma_node_start(&obj->vma_node));
1156 	drm_printf_indent(p, indent, "size=%zu\n", obj->size);
1157 	drm_printf_indent(p, indent, "imported=%s\n",
1158 			  str_yes_no(obj->import_attach));
1159 
1160 	if (obj->funcs->print_info)
1161 		obj->funcs->print_info(p, indent, obj);
1162 }
1163 
drm_gem_pin(struct drm_gem_object * obj)1164 int drm_gem_pin(struct drm_gem_object *obj)
1165 {
1166 	if (obj->funcs->pin)
1167 		return obj->funcs->pin(obj);
1168 
1169 	return 0;
1170 }
1171 
drm_gem_unpin(struct drm_gem_object * obj)1172 void drm_gem_unpin(struct drm_gem_object *obj)
1173 {
1174 	if (obj->funcs->unpin)
1175 		obj->funcs->unpin(obj);
1176 }
1177 
drm_gem_vmap(struct drm_gem_object * obj,struct iosys_map * map)1178 int drm_gem_vmap(struct drm_gem_object *obj, struct iosys_map *map)
1179 {
1180 	int ret;
1181 
1182 	dma_resv_assert_held(obj->resv);
1183 
1184 	if (!obj->funcs->vmap)
1185 		return -EOPNOTSUPP;
1186 
1187 	ret = obj->funcs->vmap(obj, map);
1188 	if (ret)
1189 		return ret;
1190 	else if (iosys_map_is_null(map))
1191 		return -ENOMEM;
1192 
1193 	return 0;
1194 }
1195 EXPORT_SYMBOL(drm_gem_vmap);
1196 
drm_gem_vunmap(struct drm_gem_object * obj,struct iosys_map * map)1197 void drm_gem_vunmap(struct drm_gem_object *obj, struct iosys_map *map)
1198 {
1199 	dma_resv_assert_held(obj->resv);
1200 
1201 	if (iosys_map_is_null(map))
1202 		return;
1203 
1204 	if (obj->funcs->vunmap)
1205 		obj->funcs->vunmap(obj, map);
1206 
1207 	/* Always set the mapping to NULL. Callers may rely on this. */
1208 	iosys_map_clear(map);
1209 }
1210 EXPORT_SYMBOL(drm_gem_vunmap);
1211 
drm_gem_vmap_unlocked(struct drm_gem_object * obj,struct iosys_map * map)1212 int drm_gem_vmap_unlocked(struct drm_gem_object *obj, struct iosys_map *map)
1213 {
1214 	int ret;
1215 
1216 	dma_resv_lock(obj->resv, NULL);
1217 	ret = drm_gem_vmap(obj, map);
1218 	dma_resv_unlock(obj->resv);
1219 
1220 	return ret;
1221 }
1222 EXPORT_SYMBOL(drm_gem_vmap_unlocked);
1223 
drm_gem_vunmap_unlocked(struct drm_gem_object * obj,struct iosys_map * map)1224 void drm_gem_vunmap_unlocked(struct drm_gem_object *obj, struct iosys_map *map)
1225 {
1226 	dma_resv_lock(obj->resv, NULL);
1227 	drm_gem_vunmap(obj, map);
1228 	dma_resv_unlock(obj->resv);
1229 }
1230 EXPORT_SYMBOL(drm_gem_vunmap_unlocked);
1231 
1232 /**
1233  * drm_gem_lock_reservations - Sets up the ww context and acquires
1234  * the lock on an array of GEM objects.
1235  *
1236  * Once you've locked your reservations, you'll want to set up space
1237  * for your shared fences (if applicable), submit your job, then
1238  * drm_gem_unlock_reservations().
1239  *
1240  * @objs: drm_gem_objects to lock
1241  * @count: Number of objects in @objs
1242  * @acquire_ctx: struct ww_acquire_ctx that will be initialized as
1243  * part of tracking this set of locked reservations.
1244  */
1245 int
drm_gem_lock_reservations(struct drm_gem_object ** objs,int count,struct ww_acquire_ctx * acquire_ctx)1246 drm_gem_lock_reservations(struct drm_gem_object **objs, int count,
1247 			  struct ww_acquire_ctx *acquire_ctx)
1248 {
1249 	int contended = -1;
1250 	int i, ret;
1251 
1252 	ww_acquire_init(acquire_ctx, &reservation_ww_class);
1253 
1254 retry:
1255 	if (contended != -1) {
1256 		struct drm_gem_object *obj = objs[contended];
1257 
1258 		ret = dma_resv_lock_slow_interruptible(obj->resv,
1259 								 acquire_ctx);
1260 		if (ret) {
1261 			ww_acquire_fini(acquire_ctx);
1262 			return ret;
1263 		}
1264 	}
1265 
1266 	for (i = 0; i < count; i++) {
1267 		if (i == contended)
1268 			continue;
1269 
1270 		ret = dma_resv_lock_interruptible(objs[i]->resv,
1271 							    acquire_ctx);
1272 		if (ret) {
1273 			int j;
1274 
1275 			for (j = 0; j < i; j++)
1276 				dma_resv_unlock(objs[j]->resv);
1277 
1278 			if (contended != -1 && contended >= i)
1279 				dma_resv_unlock(objs[contended]->resv);
1280 
1281 			if (ret == -EDEADLK) {
1282 				contended = i;
1283 				goto retry;
1284 			}
1285 
1286 			ww_acquire_fini(acquire_ctx);
1287 			return ret;
1288 		}
1289 	}
1290 
1291 	ww_acquire_done(acquire_ctx);
1292 
1293 	return 0;
1294 }
1295 EXPORT_SYMBOL(drm_gem_lock_reservations);
1296 
1297 void
drm_gem_unlock_reservations(struct drm_gem_object ** objs,int count,struct ww_acquire_ctx * acquire_ctx)1298 drm_gem_unlock_reservations(struct drm_gem_object **objs, int count,
1299 			    struct ww_acquire_ctx *acquire_ctx)
1300 {
1301 	int i;
1302 
1303 	for (i = 0; i < count; i++)
1304 		dma_resv_unlock(objs[i]->resv);
1305 
1306 	ww_acquire_fini(acquire_ctx);
1307 }
1308 EXPORT_SYMBOL(drm_gem_unlock_reservations);
1309 
1310 /**
1311  * drm_gem_lru_init - initialize a LRU
1312  *
1313  * @lru: The LRU to initialize
1314  * @lock: The lock protecting the LRU
1315  */
1316 void
drm_gem_lru_init(struct drm_gem_lru * lru,struct mutex * lock)1317 drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock)
1318 {
1319 	lru->lock = lock;
1320 	lru->count = 0;
1321 	INIT_LIST_HEAD(&lru->list);
1322 }
1323 EXPORT_SYMBOL(drm_gem_lru_init);
1324 
1325 static void
drm_gem_lru_remove_locked(struct drm_gem_object * obj)1326 drm_gem_lru_remove_locked(struct drm_gem_object *obj)
1327 {
1328 	obj->lru->count -= obj->size >> PAGE_SHIFT;
1329 	WARN_ON(obj->lru->count < 0);
1330 	list_del(&obj->lru_node);
1331 	obj->lru = NULL;
1332 }
1333 
1334 /**
1335  * drm_gem_lru_remove - remove object from whatever LRU it is in
1336  *
1337  * If the object is currently in any LRU, remove it.
1338  *
1339  * @obj: The GEM object to remove from current LRU
1340  */
1341 void
drm_gem_lru_remove(struct drm_gem_object * obj)1342 drm_gem_lru_remove(struct drm_gem_object *obj)
1343 {
1344 	struct drm_gem_lru *lru = obj->lru;
1345 
1346 	if (!lru)
1347 		return;
1348 
1349 	mutex_lock(lru->lock);
1350 	drm_gem_lru_remove_locked(obj);
1351 	mutex_unlock(lru->lock);
1352 }
1353 EXPORT_SYMBOL(drm_gem_lru_remove);
1354 
1355 /**
1356  * drm_gem_lru_move_tail_locked - move the object to the tail of the LRU
1357  *
1358  * Like &drm_gem_lru_move_tail but lru lock must be held
1359  *
1360  * @lru: The LRU to move the object into.
1361  * @obj: The GEM object to move into this LRU
1362  */
1363 void
drm_gem_lru_move_tail_locked(struct drm_gem_lru * lru,struct drm_gem_object * obj)1364 drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj)
1365 {
1366 	lockdep_assert_held_once(lru->lock);
1367 
1368 	if (obj->lru)
1369 		drm_gem_lru_remove_locked(obj);
1370 
1371 	lru->count += obj->size >> PAGE_SHIFT;
1372 	list_add_tail(&obj->lru_node, &lru->list);
1373 	obj->lru = lru;
1374 }
1375 EXPORT_SYMBOL(drm_gem_lru_move_tail_locked);
1376 
1377 /**
1378  * drm_gem_lru_move_tail - move the object to the tail of the LRU
1379  *
1380  * If the object is already in this LRU it will be moved to the
1381  * tail.  Otherwise it will be removed from whichever other LRU
1382  * it is in (if any) and moved into this LRU.
1383  *
1384  * @lru: The LRU to move the object into.
1385  * @obj: The GEM object to move into this LRU
1386  */
1387 void
drm_gem_lru_move_tail(struct drm_gem_lru * lru,struct drm_gem_object * obj)1388 drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj)
1389 {
1390 	mutex_lock(lru->lock);
1391 	drm_gem_lru_move_tail_locked(lru, obj);
1392 	mutex_unlock(lru->lock);
1393 }
1394 EXPORT_SYMBOL(drm_gem_lru_move_tail);
1395 
1396 /**
1397  * drm_gem_lru_scan - helper to implement shrinker.scan_objects
1398  *
1399  * If the shrink callback succeeds, it is expected that the driver
1400  * move the object out of this LRU.
1401  *
1402  * If the LRU possibly contain active buffers, it is the responsibility
1403  * of the shrink callback to check for this (ie. dma_resv_test_signaled())
1404  * or if necessary block until the buffer becomes idle.
1405  *
1406  * @lru: The LRU to scan
1407  * @nr_to_scan: The number of pages to try to reclaim
1408  * @remaining: The number of pages left to reclaim, should be initialized by caller
1409  * @shrink: Callback to try to shrink/reclaim the object.
1410  */
1411 unsigned long
drm_gem_lru_scan(struct drm_gem_lru * lru,unsigned int nr_to_scan,unsigned long * remaining,bool (* shrink)(struct drm_gem_object * obj))1412 drm_gem_lru_scan(struct drm_gem_lru *lru,
1413 		 unsigned int nr_to_scan,
1414 		 unsigned long *remaining,
1415 		 bool (*shrink)(struct drm_gem_object *obj))
1416 {
1417 	struct drm_gem_lru still_in_lru;
1418 	struct drm_gem_object *obj;
1419 	unsigned freed = 0;
1420 
1421 	drm_gem_lru_init(&still_in_lru, lru->lock);
1422 
1423 	mutex_lock(lru->lock);
1424 
1425 	while (freed < nr_to_scan) {
1426 		obj = list_first_entry_or_null(&lru->list, typeof(*obj), lru_node);
1427 
1428 		if (!obj)
1429 			break;
1430 
1431 		drm_gem_lru_move_tail_locked(&still_in_lru, obj);
1432 
1433 		/*
1434 		 * If it's in the process of being freed, gem_object->free()
1435 		 * may be blocked on lock waiting to remove it.  So just
1436 		 * skip it.
1437 		 */
1438 		if (!kref_get_unless_zero(&obj->refcount))
1439 			continue;
1440 
1441 		/*
1442 		 * Now that we own a reference, we can drop the lock for the
1443 		 * rest of the loop body, to reduce contention with other
1444 		 * code paths that need the LRU lock
1445 		 */
1446 		mutex_unlock(lru->lock);
1447 
1448 		/*
1449 		 * Note that this still needs to be trylock, since we can
1450 		 * hit shrinker in response to trying to get backing pages
1451 		 * for this obj (ie. while it's lock is already held)
1452 		 */
1453 		if (!dma_resv_trylock(obj->resv)) {
1454 			*remaining += obj->size >> PAGE_SHIFT;
1455 			goto tail;
1456 		}
1457 
1458 		if (shrink(obj)) {
1459 			freed += obj->size >> PAGE_SHIFT;
1460 
1461 			/*
1462 			 * If we succeeded in releasing the object's backing
1463 			 * pages, we expect the driver to have moved the object
1464 			 * out of this LRU
1465 			 */
1466 			WARN_ON(obj->lru == &still_in_lru);
1467 			WARN_ON(obj->lru == lru);
1468 		}
1469 
1470 		dma_resv_unlock(obj->resv);
1471 
1472 tail:
1473 		drm_gem_object_put(obj);
1474 		mutex_lock(lru->lock);
1475 	}
1476 
1477 	/*
1478 	 * Move objects we've skipped over out of the temporary still_in_lru
1479 	 * back into this LRU
1480 	 */
1481 	list_for_each_entry (obj, &still_in_lru.list, lru_node)
1482 		obj->lru = lru;
1483 	list_splice_tail(&still_in_lru.list, &lru->list);
1484 	lru->count += still_in_lru.count;
1485 
1486 	mutex_unlock(lru->lock);
1487 
1488 	return freed;
1489 }
1490 EXPORT_SYMBOL(drm_gem_lru_scan);
1491 
1492 /**
1493  * drm_gem_evict - helper to evict backing pages for a GEM object
1494  * @obj: obj in question
1495  */
drm_gem_evict(struct drm_gem_object * obj)1496 int drm_gem_evict(struct drm_gem_object *obj)
1497 {
1498 	dma_resv_assert_held(obj->resv);
1499 
1500 	if (!dma_resv_test_signaled(obj->resv, DMA_RESV_USAGE_READ))
1501 		return -EBUSY;
1502 
1503 	if (obj->funcs->evict)
1504 		return obj->funcs->evict(obj);
1505 
1506 	return 0;
1507 }
1508 EXPORT_SYMBOL(drm_gem_evict);
1509