summaryrefslogtreecommitdiff
path: root/drivers/gpu/drm/drm_gem_shmem_helper.c
blob: d77c9f8ff26ced1e994792f36e4cc49321bb31f3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2018 Noralf Trønnes
 */

#include <linux/dma-buf.h>
#include <linux/export.h>
#include <linux/mutex.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>

#include <drm/drm.h>
#include <drm/drm_device.h>
#include <drm/drm_drv.h>
#include <drm/drm_gem_shmem_helper.h>
#include <drm/drm_prime.h>
#include <drm/drm_print.h>

/**
 * DOC: overview
 *
 * This library provides helpers for GEM objects backed by shmem buffers
 * allocated using anonymous pageable memory.
 */

static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
	.free = drm_gem_shmem_free_object,
	.print_info = drm_gem_shmem_print_info,
	.pin = drm_gem_shmem_pin,
	.unpin = drm_gem_shmem_unpin,
	.get_sg_table = drm_gem_shmem_get_sg_table,
	.vmap = drm_gem_shmem_vmap,
	.vunmap = drm_gem_shmem_vunmap,
	.mmap = drm_gem_shmem_mmap,
};

static struct drm_gem_shmem_object *
__drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
{
	struct drm_gem_shmem_object *shmem;
	struct drm_gem_object *obj;
	int ret = 0;

	size = PAGE_ALIGN(size);

	if (dev->driver->gem_create_object)
		obj = dev->driver->gem_create_object(dev, size);
	else
		obj = kzalloc(sizeof(*shmem), GFP_KERNEL);
	if (!obj)
		return ERR_PTR(-ENOMEM);

	if (!obj->funcs)
		obj->funcs = &drm_gem_shmem_funcs;

	if (private)
		drm_gem_private_object_init(dev, obj, size);
	else
		ret = drm_gem_object_init(dev, obj, size);
	if (ret)
		goto err_free;

	ret = drm_gem_create_mmap_offset(obj);
	if (ret)
		goto err_release;

	shmem = to_drm_gem_shmem_obj(obj);
	mutex_init(&shmem->pages_lock);
	mutex_init(&shmem->vmap_lock);
	INIT_LIST_HEAD(&shmem->madv_list);

	if (!private) {
		/*
		 * Our buffers are kept pinned, so allocating them
		 * from the MOVABLE zone is a really bad idea, and
		 * conflicts with CMA. See comments above new_inode()
		 * why this is required _and_ expected if you're
		 * going to pin these pages.
		 */
		mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER |
				     __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
	}

	return shmem;

err_release:
	drm_gem_object_release(obj);
err_free:
	kfree(obj);

	return ERR_PTR(ret);
}
/**
 * drm_gem_shmem_create - Allocate an object with the given size
 * @dev: DRM device
 * @size: Size of the object to allocate
 *
 * This function creates a shmem GEM object.
 *
 * Returns:
 * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
 * error code on failure.
 */
struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
{
	return __drm_gem_shmem_create(dev, size, false);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_create);

/**
 * drm_gem_shmem_free_object - Free resources associated with a shmem GEM object
 * @obj: GEM object to free
 *
 * This function cleans up the GEM object state and frees the memory used to
 * store the object itself. It should be used to implement
 * &drm_gem_object_funcs.free.
 */
void drm_gem_shmem_free_object(struct drm_gem_object *obj)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	WARN_ON(shmem->vmap_use_count);

	if (obj->import_attach) {
		drm_prime_gem_destroy(obj, shmem->sgt);
	} else {
		if (shmem->sgt) {
			dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
					  DMA_BIDIRECTIONAL, 0);
			sg_free_table(shmem->sgt);
			kfree(shmem->sgt);
		}
		if (shmem->pages)
			drm_gem_shmem_put_pages(shmem);
	}

	WARN_ON(shmem->pages_use_count);

	drm_gem_object_release(obj);
	mutex_destroy(&shmem->pages_lock);
	mutex_destroy(&shmem->vmap_lock);
	kfree(shmem);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_free_object);

static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
{
	struct drm_gem_object *obj = &shmem->base;
	struct page **pages;

	if (shmem->pages_use_count++ > 0)
		return 0;

	pages = drm_gem_get_pages(obj);
	if (IS_ERR(pages)) {
		DRM_DEBUG_KMS("Failed to get pages (%ld)\n", PTR_ERR(pages));
		shmem->pages_use_count = 0;
		return PTR_ERR(pages);
	}

	shmem->pages = pages;

	return 0;
}

/*
 * drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
 * @shmem: shmem GEM object
 *
 * This function makes sure that backing pages exists for the shmem GEM object
 * and increases the use count.
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 */
int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
{
	int ret;

	WARN_ON(shmem->base.import_attach);

	ret = mutex_lock_interruptible(&shmem->pages_lock);
	if (ret)
		return ret;
	ret = drm_gem_shmem_get_pages_locked(shmem);
	mutex_unlock(&shmem->pages_lock);

	return ret;
}
EXPORT_SYMBOL(drm_gem_shmem_get_pages);

static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
{
	struct drm_gem_object *obj = &shmem->base;

	if (WARN_ON_ONCE(!shmem->pages_use_count))
		return;

	if (--shmem->pages_use_count > 0)
		return;

	drm_gem_put_pages(obj, shmem->pages,
			  shmem->pages_mark_dirty_on_put,
			  shmem->pages_mark_accessed_on_put);
	shmem->pages = NULL;
}

/*
 * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
 * @shmem: shmem GEM object
 *
 * This function decreases the use count and puts the backing pages when use drops to zero.
 */
void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
{
	mutex_lock(&shmem->pages_lock);
	drm_gem_shmem_put_pages_locked(shmem);
	mutex_unlock(&shmem->pages_lock);
}
EXPORT_SYMBOL(drm_gem_shmem_put_pages);

/**
 * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
 * @obj: GEM object
 *
 * This function makes sure the backing pages are pinned in memory while the
 * buffer is exported. It should only be used to implement
 * &drm_gem_object_funcs.pin.
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 */
int drm_gem_shmem_pin(struct drm_gem_object *obj)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	WARN_ON(shmem->base.import_attach);

	return drm_gem_shmem_get_pages(shmem);
}
EXPORT_SYMBOL(drm_gem_shmem_pin);

/**
 * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
 * @obj: GEM object
 *
 * This function removes the requirement that the backing pages are pinned in
 * memory. It should only be used to implement &drm_gem_object_funcs.unpin.
 */
void drm_gem_shmem_unpin(struct drm_gem_object *obj)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	WARN_ON(shmem->base.import_attach);

	drm_gem_shmem_put_pages(shmem);
}
EXPORT_SYMBOL(drm_gem_shmem_unpin);

static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
{
	struct drm_gem_object *obj = &shmem->base;
	int ret;

	if (shmem->vmap_use_count++ > 0)
		return shmem->vaddr;

	if (obj->import_attach) {
		shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
	} else {
		pgprot_t prot = PAGE_KERNEL;

		ret = drm_gem_shmem_get_pages(shmem);
		if (ret)
			goto err_zero_use;

		if (!shmem->map_cached)
			prot = pgprot_writecombine(prot);
		shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
				    VM_MAP, prot);
	}

	if (!shmem->vaddr) {
		DRM_DEBUG_KMS("Failed to vmap pages\n");
		ret = -ENOMEM;
		goto err_put_pages;
	}

	return shmem->vaddr;

err_put_pages:
	if (!obj->import_attach)
		drm_gem_shmem_put_pages(shmem);
err_zero_use:
	shmem->vmap_use_count = 0;

	return ERR_PTR(ret);
}

/*
 * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
 * @shmem: shmem GEM object
 *
 * This function makes sure that a contiguous kernel virtual address mapping
 * exists for the buffer backing the shmem GEM object.
 *
 * This function can be used to implement &drm_gem_object_funcs.vmap. But it can
 * also be called by drivers directly, in which case it will hide the
 * differences between dma-buf imported and natively allocated objects.
 *
 * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap().
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 */
void *drm_gem_shmem_vmap(struct drm_gem_object *obj)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
	void *vaddr;
	int ret;

	ret = mutex_lock_interruptible(&shmem->vmap_lock);
	if (ret)
		return ERR_PTR(ret);
	vaddr = drm_gem_shmem_vmap_locked(shmem);
	mutex_unlock(&shmem->vmap_lock);

	return vaddr;
}
EXPORT_SYMBOL(drm_gem_shmem_vmap);

static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem)
{
	struct drm_gem_object *obj = &shmem->base;

	if (WARN_ON_ONCE(!shmem->vmap_use_count))
		return;

	if (--shmem->vmap_use_count > 0)
		return;

	if (obj->import_attach)
		dma_buf_vunmap(obj->import_attach->dmabuf, shmem->vaddr);
	else
		vunmap(shmem->vaddr);

	shmem->vaddr = NULL;
	drm_gem_shmem_put_pages(shmem);
}

/*
 * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
 * @shmem: shmem GEM object
 *
 * This function cleans up a kernel virtual address mapping acquired by
 * drm_gem_shmem_vmap(). The mapping is only removed when the use count drops to
 * zero.
 *
 * This function can be used to implement &drm_gem_object_funcs.vmap. But it can
 * also be called by drivers directly, in which case it will hide the
 * differences between dma-buf imported and natively allocated objects.
 */
void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	mutex_lock(&shmem->vmap_lock);
	drm_gem_shmem_vunmap_locked(shmem);
	mutex_unlock(&shmem->vmap_lock);
}
EXPORT_SYMBOL(drm_gem_shmem_vunmap);

struct drm_gem_shmem_object *
drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
				 struct drm_device *dev, size_t size,
				 uint32_t *handle)
{
	struct drm_gem_shmem_object *shmem;
	int ret;

	shmem = drm_gem_shmem_create(dev, size);
	if (IS_ERR(shmem))
		return shmem;

	/*
	 * Allocate an id of idr table where the obj is registered
	 * and handle has the id what user can see.
	 */
	ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
	/* drop reference from allocate - handle holds it now. */
	drm_gem_object_put(&shmem->base);
	if (ret)
		return ERR_PTR(ret);

	return shmem;
}
EXPORT_SYMBOL(drm_gem_shmem_create_with_handle);

/* Update madvise status, returns true if not purged, else
 * false or -errno.
 */
int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	mutex_lock(&shmem->pages_lock);

	if (shmem->madv >= 0)
		shmem->madv = madv;

	madv = shmem->madv;

	mutex_unlock(&shmem->pages_lock);

	return (madv >= 0);
}
EXPORT_SYMBOL(drm_gem_shmem_madvise);

void drm_gem_shmem_purge_locked(struct drm_gem_object *obj)
{
	struct drm_device *dev = obj->dev;
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	WARN_ON(!drm_gem_shmem_is_purgeable(shmem));

	dma_unmap_sgtable(obj->dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
	sg_free_table(shmem->sgt);
	kfree(shmem->sgt);
	shmem->sgt = NULL;

	drm_gem_shmem_put_pages_locked(shmem);

	shmem->madv = -1;

	drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
	drm_gem_free_mmap_offset(obj);

	/* Our goal here is to return as much of the memory as
	 * is possible back to the system as we are called from OOM.
	 * To do this we must instruct the shmfs to drop all of its
	 * backing pages, *now*.
	 */
	shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);

	invalidate_mapping_pages(file_inode(obj->filp)->i_mapping,
			0, (loff_t)-1);
}
EXPORT_SYMBOL(drm_gem_shmem_purge_locked);

bool drm_gem_shmem_purge(struct drm_gem_object *obj)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	if (!mutex_trylock(&shmem->pages_lock))
		return false;
	drm_gem_shmem_purge_locked(obj);
	mutex_unlock(&shmem->pages_lock);

	return true;
}
EXPORT_SYMBOL(drm_gem_shmem_purge);

/**
 * drm_gem_shmem_create_object_cached - Create a shmem buffer object with
 *                                      cached mappings
 * @dev: DRM device
 * @size: Size of the object to allocate
 *
 * By default, shmem buffer objects use writecombine mappings. This
 * function implements struct drm_driver.gem_create_object for shmem
 * buffer objects with cached mappings.
 *
 * Returns:
 * A struct drm_gem_shmem_object * on success or NULL negative on failure.
 */
struct drm_gem_object *
drm_gem_shmem_create_object_cached(struct drm_device *dev, size_t size)
{
	struct drm_gem_shmem_object *shmem;

	shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
	if (!shmem)
		return NULL;
	shmem->map_cached = true;

	return &shmem->base;
}
EXPORT_SYMBOL(drm_gem_shmem_create_object_cached);

/**
 * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
 * @file: DRM file structure to create the dumb buffer for
 * @dev: DRM device
 * @args: IOCTL data
 *
 * This function computes the pitch of the dumb buffer and rounds it up to an
 * integer number of bytes per pixel. Drivers for hardware that doesn't have
 * any additional restrictions on the pitch can directly use this function as
 * their &drm_driver.dumb_create callback.
 *
 * For hardware with additional restrictions, drivers can adjust the fields
 * set up by userspace before calling into this function.
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 */
int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
			      struct drm_mode_create_dumb *args)
{
	u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
	struct drm_gem_shmem_object *shmem;

	if (!args->pitch || !args->size) {
		args->pitch = min_pitch;
		args->size = args->pitch * args->height;
	} else {
		/* ensure sane minimum values */
		if (args->pitch < min_pitch)
			args->pitch = min_pitch;
		if (args->size < args->pitch * args->height)
			args->size = args->pitch * args->height;
	}

	shmem = drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);

	return PTR_ERR_OR_ZERO(shmem);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);

static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
{
	struct vm_area_struct *vma = vmf->vma;
	struct drm_gem_object *obj = vma->vm_private_data;
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
	loff_t num_pages = obj->size >> PAGE_SHIFT;
	struct page *page;

	if (vmf->pgoff >= num_pages || WARN_ON_ONCE(!shmem->pages))
		return VM_FAULT_SIGBUS;

	page = shmem->pages[vmf->pgoff];

	return vmf_insert_page(vma, vmf->address, page);
}

static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
{
	struct drm_gem_object *obj = vma->vm_private_data;
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
	int ret;

	WARN_ON(shmem->base.import_attach);

	ret = drm_gem_shmem_get_pages(shmem);
	WARN_ON_ONCE(ret != 0);

	drm_gem_vm_open(vma);
}

static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
{
	struct drm_gem_object *obj = vma->vm_private_data;
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	drm_gem_shmem_put_pages(shmem);
	drm_gem_vm_close(vma);
}

static const struct vm_operations_struct drm_gem_shmem_vm_ops = {
	.fault = drm_gem_shmem_fault,
	.open = drm_gem_shmem_vm_open,
	.close = drm_gem_shmem_vm_close,
};

/**
 * drm_gem_shmem_mmap - Memory-map a shmem GEM object
 * @obj: gem object
 * @vma: VMA for the area to be mapped
 *
 * This function implements an augmented version of the GEM DRM file mmap
 * operation for shmem objects. Drivers which employ the shmem helpers should
 * use this function as their &drm_gem_object_funcs.mmap handler.
 *
 * Returns:
 * 0 on success or a negative error code on failure.
 */
int drm_gem_shmem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
{
	struct drm_gem_shmem_object *shmem;
	int ret;

	/* Remove the fake offset */
	vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);

	if (obj->import_attach)
		return dma_buf_mmap(obj->dma_buf, vma, 0);

	shmem = to_drm_gem_shmem_obj(obj);

	ret = drm_gem_shmem_get_pages(shmem);
	if (ret) {
		drm_gem_vm_close(vma);
		return ret;
	}

	vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
	if (!shmem->map_cached)
		vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
	vma->vm_ops = &drm_gem_shmem_vm_ops;

	return 0;
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);

/**
 * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
 * @p: DRM printer
 * @indent: Tab indentation level
 * @obj: GEM object
 *
 * This implements the &drm_gem_object_funcs.info callback.
 */
void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
			      const struct drm_gem_object *obj)
{
	const struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
	drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
	drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
}
EXPORT_SYMBOL(drm_gem_shmem_print_info);

/**
 * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
 *                              pages for a shmem GEM object
 * @obj: GEM object
 *
 * This function exports a scatter/gather table suitable for PRIME usage by
 * calling the standard DMA mapping API. Drivers should not call this function
 * directly, instead it should only be used as an implementation for
 * &drm_gem_object_funcs.get_sg_table.
 *
 * Drivers who need to acquire an scatter/gather table for objects need to call
 * drm_gem_shmem_get_pages_sgt() instead.
 *
 * Returns:
 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
 */
struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
{
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);

	WARN_ON(shmem->base.import_attach);

	return drm_prime_pages_to_sg(obj->dev, shmem->pages, obj->size >> PAGE_SHIFT);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);

/**
 * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
 *				 scatter/gather table for a shmem GEM object.
 * @obj: GEM object
 *
 * This function returns a scatter/gather table suitable for driver usage. If
 * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
 * table created.
 *
 * This is the main function for drivers to get at backing storage, and it hides
 * and difference between dma-buf imported and natively allocated objects.
 * drm_gem_shmem_get_sg_table() should not be directly called by drivers.
 *
 * Returns:
 * A pointer to the scatter/gather table of pinned pages or errno on failure.
 */
struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
{
	int ret;
	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
	struct sg_table *sgt;

	if (shmem->sgt)
		return shmem->sgt;

	WARN_ON(obj->import_attach);

	ret = drm_gem_shmem_get_pages(shmem);
	if (ret)
		return ERR_PTR(ret);

	sgt = drm_gem_shmem_get_sg_table(&shmem->base);
	if (IS_ERR(sgt)) {
		ret = PTR_ERR(sgt);
		goto err_put_pages;
	}
	/* Map the pages for use by the h/w. */
	ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0);
	if (ret)
		goto err_free_sgt;

	shmem->sgt = sgt;

	return sgt;

err_free_sgt:
	sg_free_table(sgt);
	kfree(sgt);
err_put_pages:
	drm_gem_shmem_put_pages(shmem);
	return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);

/**
 * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
 *                 another driver's scatter/gather table of pinned pages
 * @dev: Device to import into
 * @attach: DMA-BUF attachment
 * @sgt: Scatter/gather table of pinned pages
 *
 * This function imports a scatter/gather table exported via DMA-BUF by
 * another driver. Drivers that use the shmem helpers should set this as their
 * &drm_driver.gem_prime_import_sg_table callback.
 *
 * Returns:
 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
 * error code on failure.
 */
struct drm_gem_object *
drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
				    struct dma_buf_attachment *attach,
				    struct sg_table *sgt)
{
	size_t size = PAGE_ALIGN(attach->dmabuf->size);
	struct drm_gem_shmem_object *shmem;

	shmem = __drm_gem_shmem_create(dev, size, true);
	if (IS_ERR(shmem))
		return ERR_CAST(shmem);

	shmem->sgt = sgt;

	DRM_DEBUG_PRIME("size = %zu\n", size);

	return &shmem->base;
}
EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);