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