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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2018 Noralf Trønnes
4 */
5
6#include <linux/dma-buf.h>
7#include <linux/export.h>
8#include <linux/module.h>
9#include <linux/mutex.h>
10#include <linux/shmem_fs.h>
11#include <linux/slab.h>
12#include <linux/vmalloc.h>
13
14#ifdef CONFIG_X86
15#include <asm/set_memory.h>
16#endif
17
18#include <drm/drm.h>
19#include <drm/drm_device.h>
20#include <drm/drm_drv.h>
21#include <drm/drm_gem_shmem_helper.h>
22#include <drm/drm_prime.h>
23#include <drm/drm_print.h>
24
25MODULE_IMPORT_NS("DMA_BUF");
26
27/**
28 * DOC: overview
29 *
30 * This library provides helpers for GEM objects backed by shmem buffers
31 * allocated using anonymous pageable memory.
32 *
33 * Functions that operate on the GEM object receive struct &drm_gem_shmem_object.
34 * For GEM callback helpers in struct &drm_gem_object functions, see likewise
35 * named functions with an _object_ infix (e.g., drm_gem_shmem_object_vmap() wraps
36 * drm_gem_shmem_vmap()). These helpers perform the necessary type conversion.
37 */
38
39static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
40 .free = drm_gem_shmem_object_free,
41 .print_info = drm_gem_shmem_object_print_info,
42 .pin = drm_gem_shmem_object_pin,
43 .unpin = drm_gem_shmem_object_unpin,
44 .get_sg_table = drm_gem_shmem_object_get_sg_table,
45 .vmap = drm_gem_shmem_object_vmap,
46 .vunmap = drm_gem_shmem_object_vunmap,
47 .mmap = drm_gem_shmem_object_mmap,
48 .vm_ops = &drm_gem_shmem_vm_ops,
49};
50
51static struct drm_gem_shmem_object *
52__drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private,
53 struct vfsmount *gemfs)
54{
55 struct drm_gem_shmem_object *shmem;
56 struct drm_gem_object *obj;
57 int ret = 0;
58
59 size = PAGE_ALIGN(size);
60
61 if (dev->driver->gem_create_object) {
62 obj = dev->driver->gem_create_object(dev, size);
63 if (IS_ERR(obj))
64 return ERR_CAST(obj);
65 shmem = to_drm_gem_shmem_obj(obj);
66 } else {
67 shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
68 if (!shmem)
69 return ERR_PTR(-ENOMEM);
70 obj = &shmem->base;
71 }
72
73 if (!obj->funcs)
74 obj->funcs = &drm_gem_shmem_funcs;
75
76 if (private) {
77 drm_gem_private_object_init(dev, obj, size);
78 shmem->map_wc = false; /* dma-buf mappings use always writecombine */
79 } else {
80 ret = drm_gem_object_init_with_mnt(dev, obj, size, gemfs);
81 }
82 if (ret) {
83 drm_gem_private_object_fini(obj);
84 goto err_free;
85 }
86
87 ret = drm_gem_create_mmap_offset(obj);
88 if (ret)
89 goto err_release;
90
91 INIT_LIST_HEAD(&shmem->madv_list);
92
93 if (!private) {
94 /*
95 * Our buffers are kept pinned, so allocating them
96 * from the MOVABLE zone is a really bad idea, and
97 * conflicts with CMA. See comments above new_inode()
98 * why this is required _and_ expected if you're
99 * going to pin these pages.
100 */
101 mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER |
102 __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
103 }
104
105 return shmem;
106
107err_release:
108 drm_gem_object_release(obj);
109err_free:
110 kfree(obj);
111
112 return ERR_PTR(ret);
113}
114/**
115 * drm_gem_shmem_create - Allocate an object with the given size
116 * @dev: DRM device
117 * @size: Size of the object to allocate
118 *
119 * This function creates a shmem GEM object.
120 *
121 * Returns:
122 * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
123 * error code on failure.
124 */
125struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
126{
127 return __drm_gem_shmem_create(dev, size, false, NULL);
128}
129EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
130
131/**
132 * drm_gem_shmem_create_with_mnt - Allocate an object with the given size in a
133 * given mountpoint
134 * @dev: DRM device
135 * @size: Size of the object to allocate
136 * @gemfs: tmpfs mount where the GEM object will be created
137 *
138 * This function creates a shmem GEM object in a given tmpfs mountpoint.
139 *
140 * Returns:
141 * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
142 * error code on failure.
143 */
144struct drm_gem_shmem_object *drm_gem_shmem_create_with_mnt(struct drm_device *dev,
145 size_t size,
146 struct vfsmount *gemfs)
147{
148 return __drm_gem_shmem_create(dev, size, false, gemfs);
149}
150EXPORT_SYMBOL_GPL(drm_gem_shmem_create_with_mnt);
151
152/**
153 * drm_gem_shmem_free - Free resources associated with a shmem GEM object
154 * @shmem: shmem GEM object to free
155 *
156 * This function cleans up the GEM object state and frees the memory used to
157 * store the object itself.
158 */
159void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
160{
161 struct drm_gem_object *obj = &shmem->base;
162
163 if (obj->import_attach) {
164 drm_prime_gem_destroy(obj, shmem->sgt);
165 } else {
166 dma_resv_lock(shmem->base.resv, NULL);
167
168 drm_WARN_ON(obj->dev, shmem->vmap_use_count);
169
170 if (shmem->sgt) {
171 dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
172 DMA_BIDIRECTIONAL, 0);
173 sg_free_table(shmem->sgt);
174 kfree(shmem->sgt);
175 }
176 if (shmem->pages)
177 drm_gem_shmem_put_pages(shmem);
178
179 drm_WARN_ON(obj->dev, shmem->pages_use_count);
180
181 dma_resv_unlock(shmem->base.resv);
182 }
183
184 drm_gem_object_release(obj);
185 kfree(shmem);
186}
187EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
188
189static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
190{
191 struct drm_gem_object *obj = &shmem->base;
192 struct page **pages;
193
194 dma_resv_assert_held(shmem->base.resv);
195
196 if (shmem->pages_use_count++ > 0)
197 return 0;
198
199 pages = drm_gem_get_pages(obj);
200 if (IS_ERR(pages)) {
201 drm_dbg_kms(obj->dev, "Failed to get pages (%ld)\n",
202 PTR_ERR(pages));
203 shmem->pages_use_count = 0;
204 return PTR_ERR(pages);
205 }
206
207 /*
208 * TODO: Allocating WC pages which are correctly flushed is only
209 * supported on x86. Ideal solution would be a GFP_WC flag, which also
210 * ttm_pool.c could use.
211 */
212#ifdef CONFIG_X86
213 if (shmem->map_wc)
214 set_pages_array_wc(pages, obj->size >> PAGE_SHIFT);
215#endif
216
217 shmem->pages = pages;
218
219 return 0;
220}
221
222/*
223 * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
224 * @shmem: shmem GEM object
225 *
226 * This function decreases the use count and puts the backing pages when use drops to zero.
227 */
228void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
229{
230 struct drm_gem_object *obj = &shmem->base;
231
232 dma_resv_assert_held(shmem->base.resv);
233
234 if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
235 return;
236
237 if (--shmem->pages_use_count > 0)
238 return;
239
240#ifdef CONFIG_X86
241 if (shmem->map_wc)
242 set_pages_array_wb(shmem->pages, obj->size >> PAGE_SHIFT);
243#endif
244
245 drm_gem_put_pages(obj, shmem->pages,
246 shmem->pages_mark_dirty_on_put,
247 shmem->pages_mark_accessed_on_put);
248 shmem->pages = NULL;
249}
250EXPORT_SYMBOL(drm_gem_shmem_put_pages);
251
252int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem)
253{
254 int ret;
255
256 dma_resv_assert_held(shmem->base.resv);
257
258 drm_WARN_ON(shmem->base.dev, shmem->base.import_attach);
259
260 ret = drm_gem_shmem_get_pages(shmem);
261
262 return ret;
263}
264EXPORT_SYMBOL(drm_gem_shmem_pin_locked);
265
266void drm_gem_shmem_unpin_locked(struct drm_gem_shmem_object *shmem)
267{
268 dma_resv_assert_held(shmem->base.resv);
269
270 drm_gem_shmem_put_pages(shmem);
271}
272EXPORT_SYMBOL(drm_gem_shmem_unpin_locked);
273
274/**
275 * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
276 * @shmem: shmem GEM object
277 *
278 * This function makes sure the backing pages are pinned in memory while the
279 * buffer is exported.
280 *
281 * Returns:
282 * 0 on success or a negative error code on failure.
283 */
284int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
285{
286 struct drm_gem_object *obj = &shmem->base;
287 int ret;
288
289 drm_WARN_ON(obj->dev, obj->import_attach);
290
291 ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
292 if (ret)
293 return ret;
294 ret = drm_gem_shmem_pin_locked(shmem);
295 dma_resv_unlock(shmem->base.resv);
296
297 return ret;
298}
299EXPORT_SYMBOL(drm_gem_shmem_pin);
300
301/**
302 * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
303 * @shmem: shmem GEM object
304 *
305 * This function removes the requirement that the backing pages are pinned in
306 * memory.
307 */
308void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
309{
310 struct drm_gem_object *obj = &shmem->base;
311
312 drm_WARN_ON(obj->dev, obj->import_attach);
313
314 dma_resv_lock(shmem->base.resv, NULL);
315 drm_gem_shmem_unpin_locked(shmem);
316 dma_resv_unlock(shmem->base.resv);
317}
318EXPORT_SYMBOL(drm_gem_shmem_unpin);
319
320/*
321 * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
322 * @shmem: shmem GEM object
323 * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
324 * store.
325 *
326 * This function makes sure that a contiguous kernel virtual address mapping
327 * exists for the buffer backing the shmem GEM object. It hides the differences
328 * between dma-buf imported and natively allocated objects.
329 *
330 * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap().
331 *
332 * Returns:
333 * 0 on success or a negative error code on failure.
334 */
335int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem,
336 struct iosys_map *map)
337{
338 struct drm_gem_object *obj = &shmem->base;
339 int ret = 0;
340
341 if (obj->import_attach) {
342 ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
343 if (!ret) {
344 if (drm_WARN_ON(obj->dev, map->is_iomem)) {
345 dma_buf_vunmap(obj->import_attach->dmabuf, map);
346 return -EIO;
347 }
348 }
349 } else {
350 pgprot_t prot = PAGE_KERNEL;
351
352 dma_resv_assert_held(shmem->base.resv);
353
354 if (shmem->vmap_use_count++ > 0) {
355 iosys_map_set_vaddr(map, shmem->vaddr);
356 return 0;
357 }
358
359 ret = drm_gem_shmem_get_pages(shmem);
360 if (ret)
361 goto err_zero_use;
362
363 if (shmem->map_wc)
364 prot = pgprot_writecombine(prot);
365 shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
366 VM_MAP, prot);
367 if (!shmem->vaddr)
368 ret = -ENOMEM;
369 else
370 iosys_map_set_vaddr(map, shmem->vaddr);
371 }
372
373 if (ret) {
374 drm_dbg_kms(obj->dev, "Failed to vmap pages, error %d\n", ret);
375 goto err_put_pages;
376 }
377
378 return 0;
379
380err_put_pages:
381 if (!obj->import_attach)
382 drm_gem_shmem_put_pages(shmem);
383err_zero_use:
384 shmem->vmap_use_count = 0;
385
386 return ret;
387}
388EXPORT_SYMBOL(drm_gem_shmem_vmap);
389
390/*
391 * drm_gem_shmem_vunmap - Unmap a virtual mapping for a shmem GEM object
392 * @shmem: shmem GEM object
393 * @map: Kernel virtual address where the SHMEM GEM object was mapped
394 *
395 * This function cleans up a kernel virtual address mapping acquired by
396 * drm_gem_shmem_vmap(). The mapping is only removed when the use count drops to
397 * zero.
398 *
399 * This function hides the differences between dma-buf imported and natively
400 * allocated objects.
401 */
402void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem,
403 struct iosys_map *map)
404{
405 struct drm_gem_object *obj = &shmem->base;
406
407 if (obj->import_attach) {
408 dma_buf_vunmap(obj->import_attach->dmabuf, map);
409 } else {
410 dma_resv_assert_held(shmem->base.resv);
411
412 if (drm_WARN_ON_ONCE(obj->dev, !shmem->vmap_use_count))
413 return;
414
415 if (--shmem->vmap_use_count > 0)
416 return;
417
418 vunmap(shmem->vaddr);
419 drm_gem_shmem_put_pages(shmem);
420 }
421
422 shmem->vaddr = NULL;
423}
424EXPORT_SYMBOL(drm_gem_shmem_vunmap);
425
426static int
427drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
428 struct drm_device *dev, size_t size,
429 uint32_t *handle)
430{
431 struct drm_gem_shmem_object *shmem;
432 int ret;
433
434 shmem = drm_gem_shmem_create(dev, size);
435 if (IS_ERR(shmem))
436 return PTR_ERR(shmem);
437
438 /*
439 * Allocate an id of idr table where the obj is registered
440 * and handle has the id what user can see.
441 */
442 ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
443 /* drop reference from allocate - handle holds it now. */
444 drm_gem_object_put(&shmem->base);
445
446 return ret;
447}
448
449/* Update madvise status, returns true if not purged, else
450 * false or -errno.
451 */
452int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv)
453{
454 dma_resv_assert_held(shmem->base.resv);
455
456 if (shmem->madv >= 0)
457 shmem->madv = madv;
458
459 madv = shmem->madv;
460
461 return (madv >= 0);
462}
463EXPORT_SYMBOL(drm_gem_shmem_madvise);
464
465void drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
466{
467 struct drm_gem_object *obj = &shmem->base;
468 struct drm_device *dev = obj->dev;
469
470 dma_resv_assert_held(shmem->base.resv);
471
472 drm_WARN_ON(obj->dev, !drm_gem_shmem_is_purgeable(shmem));
473
474 dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
475 sg_free_table(shmem->sgt);
476 kfree(shmem->sgt);
477 shmem->sgt = NULL;
478
479 drm_gem_shmem_put_pages(shmem);
480
481 shmem->madv = -1;
482
483 drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
484 drm_gem_free_mmap_offset(obj);
485
486 /* Our goal here is to return as much of the memory as
487 * is possible back to the system as we are called from OOM.
488 * To do this we must instruct the shmfs to drop all of its
489 * backing pages, *now*.
490 */
491 shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
492
493 invalidate_mapping_pages(file_inode(obj->filp)->i_mapping, 0, (loff_t)-1);
494}
495EXPORT_SYMBOL(drm_gem_shmem_purge);
496
497/**
498 * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
499 * @file: DRM file structure to create the dumb buffer for
500 * @dev: DRM device
501 * @args: IOCTL data
502 *
503 * This function computes the pitch of the dumb buffer and rounds it up to an
504 * integer number of bytes per pixel. Drivers for hardware that doesn't have
505 * any additional restrictions on the pitch can directly use this function as
506 * their &drm_driver.dumb_create callback.
507 *
508 * For hardware with additional restrictions, drivers can adjust the fields
509 * set up by userspace before calling into this function.
510 *
511 * Returns:
512 * 0 on success or a negative error code on failure.
513 */
514int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
515 struct drm_mode_create_dumb *args)
516{
517 u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
518
519 if (!args->pitch || !args->size) {
520 args->pitch = min_pitch;
521 args->size = PAGE_ALIGN(args->pitch * args->height);
522 } else {
523 /* ensure sane minimum values */
524 if (args->pitch < min_pitch)
525 args->pitch = min_pitch;
526 if (args->size < args->pitch * args->height)
527 args->size = PAGE_ALIGN(args->pitch * args->height);
528 }
529
530 return drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
531}
532EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
533
534static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
535{
536 struct vm_area_struct *vma = vmf->vma;
537 struct drm_gem_object *obj = vma->vm_private_data;
538 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
539 loff_t num_pages = obj->size >> PAGE_SHIFT;
540 vm_fault_t ret;
541 struct page *page;
542 pgoff_t page_offset;
543
544 /* We don't use vmf->pgoff since that has the fake offset */
545 page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
546
547 dma_resv_lock(shmem->base.resv, NULL);
548
549 if (page_offset >= num_pages ||
550 drm_WARN_ON_ONCE(obj->dev, !shmem->pages) ||
551 shmem->madv < 0) {
552 ret = VM_FAULT_SIGBUS;
553 } else {
554 page = shmem->pages[page_offset];
555
556 ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page));
557 }
558
559 dma_resv_unlock(shmem->base.resv);
560
561 return ret;
562}
563
564static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
565{
566 struct drm_gem_object *obj = vma->vm_private_data;
567 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
568
569 drm_WARN_ON(obj->dev, obj->import_attach);
570
571 dma_resv_lock(shmem->base.resv, NULL);
572
573 /*
574 * We should have already pinned the pages when the buffer was first
575 * mmap'd, vm_open() just grabs an additional reference for the new
576 * mm the vma is getting copied into (ie. on fork()).
577 */
578 if (!drm_WARN_ON_ONCE(obj->dev, !shmem->pages_use_count))
579 shmem->pages_use_count++;
580
581 dma_resv_unlock(shmem->base.resv);
582
583 drm_gem_vm_open(vma);
584}
585
586static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
587{
588 struct drm_gem_object *obj = vma->vm_private_data;
589 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
590
591 dma_resv_lock(shmem->base.resv, NULL);
592 drm_gem_shmem_put_pages(shmem);
593 dma_resv_unlock(shmem->base.resv);
594
595 drm_gem_vm_close(vma);
596}
597
598const struct vm_operations_struct drm_gem_shmem_vm_ops = {
599 .fault = drm_gem_shmem_fault,
600 .open = drm_gem_shmem_vm_open,
601 .close = drm_gem_shmem_vm_close,
602};
603EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
604
605/**
606 * drm_gem_shmem_mmap - Memory-map a shmem GEM object
607 * @shmem: shmem GEM object
608 * @vma: VMA for the area to be mapped
609 *
610 * This function implements an augmented version of the GEM DRM file mmap
611 * operation for shmem objects.
612 *
613 * Returns:
614 * 0 on success or a negative error code on failure.
615 */
616int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma)
617{
618 struct drm_gem_object *obj = &shmem->base;
619 int ret;
620
621 if (obj->import_attach) {
622 /* Reset both vm_ops and vm_private_data, so we don't end up with
623 * vm_ops pointing to our implementation if the dma-buf backend
624 * doesn't set those fields.
625 */
626 vma->vm_private_data = NULL;
627 vma->vm_ops = NULL;
628
629 ret = dma_buf_mmap(obj->dma_buf, vma, 0);
630
631 /* Drop the reference drm_gem_mmap_obj() acquired.*/
632 if (!ret)
633 drm_gem_object_put(obj);
634
635 return ret;
636 }
637
638 if (is_cow_mapping(vma->vm_flags))
639 return -EINVAL;
640
641 dma_resv_lock(shmem->base.resv, NULL);
642 ret = drm_gem_shmem_get_pages(shmem);
643 dma_resv_unlock(shmem->base.resv);
644
645 if (ret)
646 return ret;
647
648 vm_flags_set(vma, VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
649 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
650 if (shmem->map_wc)
651 vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
652
653 return 0;
654}
655EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
656
657/**
658 * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
659 * @shmem: shmem GEM object
660 * @p: DRM printer
661 * @indent: Tab indentation level
662 */
663void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
664 struct drm_printer *p, unsigned int indent)
665{
666 if (shmem->base.import_attach)
667 return;
668
669 drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
670 drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
671 drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
672}
673EXPORT_SYMBOL(drm_gem_shmem_print_info);
674
675/**
676 * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
677 * pages for a shmem GEM object
678 * @shmem: shmem GEM object
679 *
680 * This function exports a scatter/gather table suitable for PRIME usage by
681 * calling the standard DMA mapping API.
682 *
683 * Drivers who need to acquire an scatter/gather table for objects need to call
684 * drm_gem_shmem_get_pages_sgt() instead.
685 *
686 * Returns:
687 * A pointer to the scatter/gather table of pinned pages or error pointer on failure.
688 */
689struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem)
690{
691 struct drm_gem_object *obj = &shmem->base;
692
693 drm_WARN_ON(obj->dev, obj->import_attach);
694
695 return drm_prime_pages_to_sg(obj->dev, shmem->pages, obj->size >> PAGE_SHIFT);
696}
697EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
698
699static struct sg_table *drm_gem_shmem_get_pages_sgt_locked(struct drm_gem_shmem_object *shmem)
700{
701 struct drm_gem_object *obj = &shmem->base;
702 int ret;
703 struct sg_table *sgt;
704
705 if (shmem->sgt)
706 return shmem->sgt;
707
708 drm_WARN_ON(obj->dev, obj->import_attach);
709
710 ret = drm_gem_shmem_get_pages(shmem);
711 if (ret)
712 return ERR_PTR(ret);
713
714 sgt = drm_gem_shmem_get_sg_table(shmem);
715 if (IS_ERR(sgt)) {
716 ret = PTR_ERR(sgt);
717 goto err_put_pages;
718 }
719 /* Map the pages for use by the h/w. */
720 ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0);
721 if (ret)
722 goto err_free_sgt;
723
724 shmem->sgt = sgt;
725
726 return sgt;
727
728err_free_sgt:
729 sg_free_table(sgt);
730 kfree(sgt);
731err_put_pages:
732 drm_gem_shmem_put_pages(shmem);
733 return ERR_PTR(ret);
734}
735
736/**
737 * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
738 * scatter/gather table for a shmem GEM object.
739 * @shmem: shmem GEM object
740 *
741 * This function returns a scatter/gather table suitable for driver usage. If
742 * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
743 * table created.
744 *
745 * This is the main function for drivers to get at backing storage, and it hides
746 * and difference between dma-buf imported and natively allocated objects.
747 * drm_gem_shmem_get_sg_table() should not be directly called by drivers.
748 *
749 * Returns:
750 * A pointer to the scatter/gather table of pinned pages or errno on failure.
751 */
752struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
753{
754 int ret;
755 struct sg_table *sgt;
756
757 ret = dma_resv_lock_interruptible(shmem->base.resv, NULL);
758 if (ret)
759 return ERR_PTR(ret);
760 sgt = drm_gem_shmem_get_pages_sgt_locked(shmem);
761 dma_resv_unlock(shmem->base.resv);
762
763 return sgt;
764}
765EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
766
767/**
768 * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
769 * another driver's scatter/gather table of pinned pages
770 * @dev: Device to import into
771 * @attach: DMA-BUF attachment
772 * @sgt: Scatter/gather table of pinned pages
773 *
774 * This function imports a scatter/gather table exported via DMA-BUF by
775 * another driver. Drivers that use the shmem helpers should set this as their
776 * &drm_driver.gem_prime_import_sg_table callback.
777 *
778 * Returns:
779 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
780 * error code on failure.
781 */
782struct drm_gem_object *
783drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
784 struct dma_buf_attachment *attach,
785 struct sg_table *sgt)
786{
787 size_t size = PAGE_ALIGN(attach->dmabuf->size);
788 struct drm_gem_shmem_object *shmem;
789
790 shmem = __drm_gem_shmem_create(dev, size, true, NULL);
791 if (IS_ERR(shmem))
792 return ERR_CAST(shmem);
793
794 shmem->sgt = sgt;
795
796 drm_dbg_prime(dev, "size = %zu\n", size);
797
798 return &shmem->base;
799}
800EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);
801
802MODULE_DESCRIPTION("DRM SHMEM memory-management helpers");
803MODULE_IMPORT_NS("DMA_BUF");
804MODULE_LICENSE("GPL v2");