1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright 2018 Noralf Trønnes
6 #include <linux/dma-buf.h>
7 #include <linux/export.h>
8 #include <linux/mutex.h>
9 #include <linux/shmem_fs.h>
10 #include <linux/slab.h>
11 #include <linux/vmalloc.h>
14 #include <drm/drm_device.h>
15 #include <drm/drm_drv.h>
16 #include <drm/drm_gem_shmem_helper.h>
17 #include <drm/drm_prime.h>
18 #include <drm/drm_print.h>
23 * This library provides helpers for GEM objects backed by shmem buffers
24 * allocated using anonymous pageable memory.
26 * Functions that operate on the GEM object receive struct &drm_gem_shmem_object.
27 * For GEM callback helpers in struct &drm_gem_object functions, see likewise
28 * named functions with an _object_ infix (e.g., drm_gem_shmem_object_vmap() wraps
29 * drm_gem_shmem_vmap()). These helpers perform the necessary type conversion.
32 static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
33 .free = drm_gem_shmem_object_free,
34 .print_info = drm_gem_shmem_object_print_info,
35 .pin = drm_gem_shmem_object_pin,
36 .unpin = drm_gem_shmem_object_unpin,
37 .get_sg_table = drm_gem_shmem_object_get_sg_table,
38 .vmap = drm_gem_shmem_object_vmap,
39 .vunmap = drm_gem_shmem_object_vunmap,
40 .mmap = drm_gem_shmem_object_mmap,
43 static struct drm_gem_shmem_object *
44 __drm_gem_shmem_create(struct drm_device *dev, size_t size, bool private)
46 struct drm_gem_shmem_object *shmem;
47 struct drm_gem_object *obj;
50 size = PAGE_ALIGN(size);
52 if (dev->driver->gem_create_object)
53 obj = dev->driver->gem_create_object(dev, size);
55 obj = kzalloc(sizeof(*shmem), GFP_KERNEL);
57 return ERR_PTR(-ENOMEM);
59 shmem = to_drm_gem_shmem_obj(obj);
62 obj->funcs = &drm_gem_shmem_funcs;
65 drm_gem_private_object_init(dev, obj, size);
66 shmem->map_wc = false; /* dma-buf mappings use always writecombine */
68 ret = drm_gem_object_init(dev, obj, size);
73 ret = drm_gem_create_mmap_offset(obj);
77 mutex_init(&shmem->pages_lock);
78 mutex_init(&shmem->vmap_lock);
79 INIT_LIST_HEAD(&shmem->madv_list);
83 * Our buffers are kept pinned, so allocating them
84 * from the MOVABLE zone is a really bad idea, and
85 * conflicts with CMA. See comments above new_inode()
86 * why this is required _and_ expected if you're
87 * going to pin these pages.
89 mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER |
90 __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
96 drm_gem_object_release(obj);
103 * drm_gem_shmem_create - Allocate an object with the given size
105 * @size: Size of the object to allocate
107 * This function creates a shmem GEM object.
110 * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
111 * error code on failure.
113 struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
115 return __drm_gem_shmem_create(dev, size, false);
117 EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
120 * drm_gem_shmem_free - Free resources associated with a shmem GEM object
121 * @shmem: shmem GEM object to free
123 * This function cleans up the GEM object state and frees the memory used to
124 * store the object itself.
126 void drm_gem_shmem_free(struct drm_gem_shmem_object *shmem)
128 struct drm_gem_object *obj = &shmem->base;
130 WARN_ON(shmem->vmap_use_count);
132 if (obj->import_attach) {
133 drm_prime_gem_destroy(obj, shmem->sgt);
136 dma_unmap_sgtable(obj->dev->dev, shmem->sgt,
137 DMA_BIDIRECTIONAL, 0);
138 sg_free_table(shmem->sgt);
142 drm_gem_shmem_put_pages(shmem);
145 WARN_ON(shmem->pages_use_count);
147 drm_gem_object_release(obj);
148 mutex_destroy(&shmem->pages_lock);
149 mutex_destroy(&shmem->vmap_lock);
152 EXPORT_SYMBOL_GPL(drm_gem_shmem_free);
154 static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
156 struct drm_gem_object *obj = &shmem->base;
159 if (shmem->pages_use_count++ > 0)
162 pages = drm_gem_get_pages(obj);
164 DRM_DEBUG_KMS("Failed to get pages (%ld)\n", PTR_ERR(pages));
165 shmem->pages_use_count = 0;
166 return PTR_ERR(pages);
169 shmem->pages = pages;
175 * drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
176 * @shmem: shmem GEM object
178 * This function makes sure that backing pages exists for the shmem GEM object
179 * and increases the use count.
182 * 0 on success or a negative error code on failure.
184 int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
188 WARN_ON(shmem->base.import_attach);
190 ret = mutex_lock_interruptible(&shmem->pages_lock);
193 ret = drm_gem_shmem_get_pages_locked(shmem);
194 mutex_unlock(&shmem->pages_lock);
198 EXPORT_SYMBOL(drm_gem_shmem_get_pages);
200 static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
202 struct drm_gem_object *obj = &shmem->base;
204 if (WARN_ON_ONCE(!shmem->pages_use_count))
207 if (--shmem->pages_use_count > 0)
210 drm_gem_put_pages(obj, shmem->pages,
211 shmem->pages_mark_dirty_on_put,
212 shmem->pages_mark_accessed_on_put);
217 * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
218 * @shmem: shmem GEM object
220 * This function decreases the use count and puts the backing pages when use drops to zero.
222 void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
224 mutex_lock(&shmem->pages_lock);
225 drm_gem_shmem_put_pages_locked(shmem);
226 mutex_unlock(&shmem->pages_lock);
228 EXPORT_SYMBOL(drm_gem_shmem_put_pages);
231 * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
232 * @shmem: shmem GEM object
234 * This function makes sure the backing pages are pinned in memory while the
235 * buffer is exported.
238 * 0 on success or a negative error code on failure.
240 int drm_gem_shmem_pin(struct drm_gem_shmem_object *shmem)
242 WARN_ON(shmem->base.import_attach);
244 return drm_gem_shmem_get_pages(shmem);
246 EXPORT_SYMBOL(drm_gem_shmem_pin);
249 * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
250 * @shmem: shmem GEM object
252 * This function removes the requirement that the backing pages are pinned in
255 void drm_gem_shmem_unpin(struct drm_gem_shmem_object *shmem)
257 WARN_ON(shmem->base.import_attach);
259 drm_gem_shmem_put_pages(shmem);
261 EXPORT_SYMBOL(drm_gem_shmem_unpin);
263 static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
265 struct drm_gem_object *obj = &shmem->base;
268 if (shmem->vmap_use_count++ > 0) {
269 dma_buf_map_set_vaddr(map, shmem->vaddr);
273 if (obj->import_attach) {
274 ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
276 if (WARN_ON(map->is_iomem)) {
277 dma_buf_vunmap(obj->import_attach->dmabuf, map);
281 shmem->vaddr = map->vaddr;
284 pgprot_t prot = PAGE_KERNEL;
286 ret = drm_gem_shmem_get_pages(shmem);
291 prot = pgprot_writecombine(prot);
292 shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
297 dma_buf_map_set_vaddr(map, shmem->vaddr);
301 DRM_DEBUG_KMS("Failed to vmap pages, error %d\n", ret);
308 if (!obj->import_attach)
309 drm_gem_shmem_put_pages(shmem);
311 shmem->vmap_use_count = 0;
317 * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
318 * @shmem: shmem GEM object
319 * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
322 * This function makes sure that a contiguous kernel virtual address mapping
323 * exists for the buffer backing the shmem GEM object. It hides the differences
324 * between dma-buf imported and natively allocated objects.
326 * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap().
329 * 0 on success or a negative error code on failure.
331 int drm_gem_shmem_vmap(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
335 ret = mutex_lock_interruptible(&shmem->vmap_lock);
338 ret = drm_gem_shmem_vmap_locked(shmem, map);
339 mutex_unlock(&shmem->vmap_lock);
343 EXPORT_SYMBOL(drm_gem_shmem_vmap);
345 static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
346 struct dma_buf_map *map)
348 struct drm_gem_object *obj = &shmem->base;
350 if (WARN_ON_ONCE(!shmem->vmap_use_count))
353 if (--shmem->vmap_use_count > 0)
356 if (obj->import_attach) {
357 dma_buf_vunmap(obj->import_attach->dmabuf, map);
359 vunmap(shmem->vaddr);
360 drm_gem_shmem_put_pages(shmem);
367 * drm_gem_shmem_vunmap - Unmap a virtual mapping for a shmem GEM object
368 * @shmem: shmem GEM object
369 * @map: Kernel virtual address where the SHMEM GEM object was mapped
371 * This function cleans up a kernel virtual address mapping acquired by
372 * drm_gem_shmem_vmap(). The mapping is only removed when the use count drops to
375 * This function hides the differences between dma-buf imported and natively
378 void drm_gem_shmem_vunmap(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
380 mutex_lock(&shmem->vmap_lock);
381 drm_gem_shmem_vunmap_locked(shmem, map);
382 mutex_unlock(&shmem->vmap_lock);
384 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
386 static struct drm_gem_shmem_object *
387 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
388 struct drm_device *dev, size_t size,
391 struct drm_gem_shmem_object *shmem;
394 shmem = drm_gem_shmem_create(dev, size);
399 * Allocate an id of idr table where the obj is registered
400 * and handle has the id what user can see.
402 ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
403 /* drop reference from allocate - handle holds it now. */
404 drm_gem_object_put(&shmem->base);
411 /* Update madvise status, returns true if not purged, else
414 int drm_gem_shmem_madvise(struct drm_gem_shmem_object *shmem, int madv)
416 mutex_lock(&shmem->pages_lock);
418 if (shmem->madv >= 0)
423 mutex_unlock(&shmem->pages_lock);
427 EXPORT_SYMBOL(drm_gem_shmem_madvise);
429 void drm_gem_shmem_purge_locked(struct drm_gem_shmem_object *shmem)
431 struct drm_gem_object *obj = &shmem->base;
432 struct drm_device *dev = obj->dev;
434 WARN_ON(!drm_gem_shmem_is_purgeable(shmem));
436 dma_unmap_sgtable(dev->dev, shmem->sgt, DMA_BIDIRECTIONAL, 0);
437 sg_free_table(shmem->sgt);
441 drm_gem_shmem_put_pages_locked(shmem);
445 drm_vma_node_unmap(&obj->vma_node, dev->anon_inode->i_mapping);
446 drm_gem_free_mmap_offset(obj);
448 /* Our goal here is to return as much of the memory as
449 * is possible back to the system as we are called from OOM.
450 * To do this we must instruct the shmfs to drop all of its
451 * backing pages, *now*.
453 shmem_truncate_range(file_inode(obj->filp), 0, (loff_t)-1);
455 invalidate_mapping_pages(file_inode(obj->filp)->i_mapping, 0, (loff_t)-1);
457 EXPORT_SYMBOL(drm_gem_shmem_purge_locked);
459 bool drm_gem_shmem_purge(struct drm_gem_shmem_object *shmem)
461 if (!mutex_trylock(&shmem->pages_lock))
463 drm_gem_shmem_purge_locked(shmem);
464 mutex_unlock(&shmem->pages_lock);
468 EXPORT_SYMBOL(drm_gem_shmem_purge);
471 * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
472 * @file: DRM file structure to create the dumb buffer for
476 * This function computes the pitch of the dumb buffer and rounds it up to an
477 * integer number of bytes per pixel. Drivers for hardware that doesn't have
478 * any additional restrictions on the pitch can directly use this function as
479 * their &drm_driver.dumb_create callback.
481 * For hardware with additional restrictions, drivers can adjust the fields
482 * set up by userspace before calling into this function.
485 * 0 on success or a negative error code on failure.
487 int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
488 struct drm_mode_create_dumb *args)
490 u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
491 struct drm_gem_shmem_object *shmem;
493 if (!args->pitch || !args->size) {
494 args->pitch = min_pitch;
495 args->size = PAGE_ALIGN(args->pitch * args->height);
497 /* ensure sane minimum values */
498 if (args->pitch < min_pitch)
499 args->pitch = min_pitch;
500 if (args->size < args->pitch * args->height)
501 args->size = PAGE_ALIGN(args->pitch * args->height);
504 shmem = drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
506 return PTR_ERR_OR_ZERO(shmem);
508 EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
510 static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
512 struct vm_area_struct *vma = vmf->vma;
513 struct drm_gem_object *obj = vma->vm_private_data;
514 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
515 loff_t num_pages = obj->size >> PAGE_SHIFT;
520 /* We don't use vmf->pgoff since that has the fake offset */
521 page_offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
523 mutex_lock(&shmem->pages_lock);
525 if (page_offset >= num_pages ||
526 WARN_ON_ONCE(!shmem->pages) ||
528 ret = VM_FAULT_SIGBUS;
530 page = shmem->pages[page_offset];
532 ret = vmf_insert_page(vma, vmf->address, page);
535 mutex_unlock(&shmem->pages_lock);
540 static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
542 struct drm_gem_object *obj = vma->vm_private_data;
543 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
545 WARN_ON(shmem->base.import_attach);
547 mutex_lock(&shmem->pages_lock);
550 * We should have already pinned the pages when the buffer was first
551 * mmap'd, vm_open() just grabs an additional reference for the new
552 * mm the vma is getting copied into (ie. on fork()).
554 if (!WARN_ON_ONCE(!shmem->pages_use_count))
555 shmem->pages_use_count++;
557 mutex_unlock(&shmem->pages_lock);
559 drm_gem_vm_open(vma);
562 static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
564 struct drm_gem_object *obj = vma->vm_private_data;
565 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
567 drm_gem_shmem_put_pages(shmem);
568 drm_gem_vm_close(vma);
571 static const struct vm_operations_struct drm_gem_shmem_vm_ops = {
572 .fault = drm_gem_shmem_fault,
573 .open = drm_gem_shmem_vm_open,
574 .close = drm_gem_shmem_vm_close,
578 * drm_gem_shmem_mmap - Memory-map a shmem GEM object
579 * @shmem: shmem GEM object
580 * @vma: VMA for the area to be mapped
582 * This function implements an augmented version of the GEM DRM file mmap
583 * operation for shmem objects.
586 * 0 on success or a negative error code on failure.
588 int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct *vma)
590 struct drm_gem_object *obj = &shmem->base;
593 if (obj->import_attach) {
594 /* Drop the reference drm_gem_mmap_obj() acquired.*/
595 drm_gem_object_put(obj);
596 vma->vm_private_data = NULL;
598 return dma_buf_mmap(obj->dma_buf, vma, 0);
601 ret = drm_gem_shmem_get_pages(shmem);
605 vma->vm_flags |= VM_MIXEDMAP | VM_DONTEXPAND;
606 vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
608 vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot);
609 vma->vm_ops = &drm_gem_shmem_vm_ops;
613 EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
616 * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
617 * @shmem: shmem GEM object
619 * @indent: Tab indentation level
621 void drm_gem_shmem_print_info(const struct drm_gem_shmem_object *shmem,
622 struct drm_printer *p, unsigned int indent)
624 drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
625 drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
626 drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
628 EXPORT_SYMBOL(drm_gem_shmem_print_info);
631 * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
632 * pages for a shmem GEM object
633 * @shmem: shmem GEM object
635 * This function exports a scatter/gather table suitable for PRIME usage by
636 * calling the standard DMA mapping API.
638 * Drivers who need to acquire an scatter/gather table for objects need to call
639 * drm_gem_shmem_get_pages_sgt() instead.
642 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
644 struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_shmem_object *shmem)
646 struct drm_gem_object *obj = &shmem->base;
648 WARN_ON(shmem->base.import_attach);
650 return drm_prime_pages_to_sg(obj->dev, shmem->pages, obj->size >> PAGE_SHIFT);
652 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
655 * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
656 * scatter/gather table for a shmem GEM object.
657 * @shmem: shmem GEM object
659 * This function returns a scatter/gather table suitable for driver usage. If
660 * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
663 * This is the main function for drivers to get at backing storage, and it hides
664 * and difference between dma-buf imported and natively allocated objects.
665 * drm_gem_shmem_get_sg_table() should not be directly called by drivers.
668 * A pointer to the scatter/gather table of pinned pages or errno on failure.
670 struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_shmem_object *shmem)
672 struct drm_gem_object *obj = &shmem->base;
674 struct sg_table *sgt;
679 WARN_ON(obj->import_attach);
681 ret = drm_gem_shmem_get_pages(shmem);
685 sgt = drm_gem_shmem_get_sg_table(shmem);
690 /* Map the pages for use by the h/w. */
691 ret = dma_map_sgtable(obj->dev->dev, sgt, DMA_BIDIRECTIONAL, 0);
703 drm_gem_shmem_put_pages(shmem);
706 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
709 * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
710 * another driver's scatter/gather table of pinned pages
711 * @dev: Device to import into
712 * @attach: DMA-BUF attachment
713 * @sgt: Scatter/gather table of pinned pages
715 * This function imports a scatter/gather table exported via DMA-BUF by
716 * another driver. Drivers that use the shmem helpers should set this as their
717 * &drm_driver.gem_prime_import_sg_table callback.
720 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
721 * error code on failure.
723 struct drm_gem_object *
724 drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
725 struct dma_buf_attachment *attach,
726 struct sg_table *sgt)
728 size_t size = PAGE_ALIGN(attach->dmabuf->size);
729 struct drm_gem_shmem_object *shmem;
731 shmem = __drm_gem_shmem_create(dev, size, true);
733 return ERR_CAST(shmem);
737 DRM_DEBUG_PRIME("size = %zu\n", size);
741 EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);