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>
13 #include <drm/drm_device.h>
14 #include <drm/drm_drv.h>
15 #include <drm/drm_gem_shmem_helper.h>
16 #include <drm/drm_prime.h>
17 #include <drm/drm_print.h>
22 * This library provides helpers for GEM objects backed by shmem buffers
23 * allocated using anonymous pageable memory.
26 static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
27 .free = drm_gem_shmem_free_object,
28 .print_info = drm_gem_shmem_print_info,
29 .pin = drm_gem_shmem_pin,
30 .unpin = drm_gem_shmem_unpin,
31 .get_sg_table = drm_gem_shmem_get_sg_table,
32 .vmap = drm_gem_shmem_vmap,
33 .vunmap = drm_gem_shmem_vunmap,
34 .vm_ops = &drm_gem_shmem_vm_ops,
38 * drm_gem_shmem_create - Allocate an object with the given size
40 * @size: Size of the object to allocate
42 * This function creates a shmem GEM object.
45 * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
46 * error code on failure.
48 struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
50 struct drm_gem_shmem_object *shmem;
51 struct drm_gem_object *obj;
54 size = PAGE_ALIGN(size);
56 if (dev->driver->gem_create_object)
57 obj = dev->driver->gem_create_object(dev, size);
59 obj = kzalloc(sizeof(*shmem), GFP_KERNEL);
61 return ERR_PTR(-ENOMEM);
64 obj->funcs = &drm_gem_shmem_funcs;
66 ret = drm_gem_object_init(dev, obj, size);
70 ret = drm_gem_create_mmap_offset(obj);
74 shmem = to_drm_gem_shmem_obj(obj);
75 mutex_init(&shmem->pages_lock);
76 mutex_init(&shmem->vmap_lock);
79 * Our buffers are kept pinned, so allocating them
80 * from the MOVABLE zone is a really bad idea, and
81 * conflicts with CMA. See comments above new_inode()
82 * why this is required _and_ expected if you're
83 * going to pin these pages.
85 mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER |
86 __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
91 drm_gem_object_release(obj);
97 EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
100 * drm_gem_shmem_free_object - Free resources associated with a shmem GEM object
101 * @obj: GEM object to free
103 * This function cleans up the GEM object state and frees the memory used to
104 * store the object itself.
106 void drm_gem_shmem_free_object(struct drm_gem_object *obj)
108 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
110 WARN_ON(shmem->vmap_use_count);
112 if (obj->import_attach) {
113 shmem->pages_use_count--;
114 drm_prime_gem_destroy(obj, shmem->sgt);
115 kvfree(shmem->pages);
118 dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
119 shmem->sgt->nents, DMA_BIDIRECTIONAL);
121 drm_gem_shmem_put_pages(shmem);
122 sg_free_table(shmem->sgt);
127 WARN_ON(shmem->pages_use_count);
129 drm_gem_object_release(obj);
130 mutex_destroy(&shmem->pages_lock);
131 mutex_destroy(&shmem->vmap_lock);
134 EXPORT_SYMBOL_GPL(drm_gem_shmem_free_object);
136 static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
138 struct drm_gem_object *obj = &shmem->base;
141 if (shmem->pages_use_count++ > 0)
144 pages = drm_gem_get_pages(obj);
146 DRM_DEBUG_KMS("Failed to get pages (%ld)\n", PTR_ERR(pages));
147 shmem->pages_use_count = 0;
148 return PTR_ERR(pages);
151 shmem->pages = pages;
157 * drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
158 * @shmem: shmem GEM object
160 * This function makes sure that backing pages exists for the shmem GEM object
161 * and increases the use count.
164 * 0 on success or a negative error code on failure.
166 int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
170 ret = mutex_lock_interruptible(&shmem->pages_lock);
173 ret = drm_gem_shmem_get_pages_locked(shmem);
174 mutex_unlock(&shmem->pages_lock);
178 EXPORT_SYMBOL(drm_gem_shmem_get_pages);
180 static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
182 struct drm_gem_object *obj = &shmem->base;
184 if (WARN_ON_ONCE(!shmem->pages_use_count))
187 if (--shmem->pages_use_count > 0)
190 drm_gem_put_pages(obj, shmem->pages,
191 shmem->pages_mark_dirty_on_put,
192 shmem->pages_mark_accessed_on_put);
197 * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
198 * @shmem: shmem GEM object
200 * This function decreases the use count and puts the backing pages when use drops to zero.
202 void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
204 mutex_lock(&shmem->pages_lock);
205 drm_gem_shmem_put_pages_locked(shmem);
206 mutex_unlock(&shmem->pages_lock);
208 EXPORT_SYMBOL(drm_gem_shmem_put_pages);
211 * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
214 * This function makes sure the backing pages are pinned in memory while the
215 * buffer is exported.
218 * 0 on success or a negative error code on failure.
220 int drm_gem_shmem_pin(struct drm_gem_object *obj)
222 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
224 return drm_gem_shmem_get_pages(shmem);
226 EXPORT_SYMBOL(drm_gem_shmem_pin);
229 * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
232 * This function removes the requirement that the backing pages are pinned in
235 void drm_gem_shmem_unpin(struct drm_gem_object *obj)
237 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
239 drm_gem_shmem_put_pages(shmem);
241 EXPORT_SYMBOL(drm_gem_shmem_unpin);
243 static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
245 struct drm_gem_object *obj = &shmem->base;
248 if (shmem->vmap_use_count++ > 0)
251 ret = drm_gem_shmem_get_pages(shmem);
255 if (obj->import_attach)
256 shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
258 shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
259 VM_MAP, pgprot_writecombine(PAGE_KERNEL));
262 DRM_DEBUG_KMS("Failed to vmap pages\n");
270 drm_gem_shmem_put_pages(shmem);
272 shmem->vmap_use_count = 0;
278 * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
279 * @shmem: shmem GEM object
281 * This function makes sure that a virtual address exists for the buffer backing
282 * the shmem GEM object.
285 * 0 on success or a negative error code on failure.
287 void *drm_gem_shmem_vmap(struct drm_gem_object *obj)
289 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
293 ret = mutex_lock_interruptible(&shmem->vmap_lock);
296 vaddr = drm_gem_shmem_vmap_locked(shmem);
297 mutex_unlock(&shmem->vmap_lock);
301 EXPORT_SYMBOL(drm_gem_shmem_vmap);
303 static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem)
305 struct drm_gem_object *obj = &shmem->base;
307 if (WARN_ON_ONCE(!shmem->vmap_use_count))
310 if (--shmem->vmap_use_count > 0)
313 if (obj->import_attach)
314 dma_buf_vunmap(obj->import_attach->dmabuf, shmem->vaddr);
316 vunmap(shmem->vaddr);
319 drm_gem_shmem_put_pages(shmem);
323 * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
324 * @shmem: shmem GEM object
326 * This function removes the virtual address when use count drops to zero.
328 void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr)
330 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
332 mutex_lock(&shmem->vmap_lock);
333 drm_gem_shmem_vunmap_locked(shmem);
334 mutex_unlock(&shmem->vmap_lock);
336 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
338 struct drm_gem_shmem_object *
339 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
340 struct drm_device *dev, size_t size,
343 struct drm_gem_shmem_object *shmem;
346 shmem = drm_gem_shmem_create(dev, size);
351 * Allocate an id of idr table where the obj is registered
352 * and handle has the id what user can see.
354 ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
355 /* drop reference from allocate - handle holds it now. */
356 drm_gem_object_put_unlocked(&shmem->base);
362 EXPORT_SYMBOL(drm_gem_shmem_create_with_handle);
365 * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
366 * @file: DRM file structure to create the dumb buffer for
370 * This function computes the pitch of the dumb buffer and rounds it up to an
371 * integer number of bytes per pixel. Drivers for hardware that doesn't have
372 * any additional restrictions on the pitch can directly use this function as
373 * their &drm_driver.dumb_create callback.
375 * For hardware with additional restrictions, drivers can adjust the fields
376 * set up by userspace before calling into this function.
379 * 0 on success or a negative error code on failure.
381 int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
382 struct drm_mode_create_dumb *args)
384 u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
385 struct drm_gem_shmem_object *shmem;
387 if (!args->pitch || !args->size) {
388 args->pitch = min_pitch;
389 args->size = args->pitch * args->height;
391 /* ensure sane minimum values */
392 if (args->pitch < min_pitch)
393 args->pitch = min_pitch;
394 if (args->size < args->pitch * args->height)
395 args->size = args->pitch * args->height;
398 shmem = drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
400 return PTR_ERR_OR_ZERO(shmem);
402 EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
404 static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
406 struct vm_area_struct *vma = vmf->vma;
407 struct drm_gem_object *obj = vma->vm_private_data;
408 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
409 loff_t num_pages = obj->size >> PAGE_SHIFT;
412 if (vmf->pgoff >= num_pages || WARN_ON_ONCE(!shmem->pages))
413 return VM_FAULT_SIGBUS;
415 page = shmem->pages[vmf->pgoff];
417 return vmf_insert_page(vma, vmf->address, page);
420 static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
422 struct drm_gem_object *obj = vma->vm_private_data;
423 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
426 ret = drm_gem_shmem_get_pages(shmem);
427 WARN_ON_ONCE(ret != 0);
429 drm_gem_vm_open(vma);
432 static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
434 struct drm_gem_object *obj = vma->vm_private_data;
435 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
437 drm_gem_shmem_put_pages(shmem);
438 drm_gem_vm_close(vma);
441 const struct vm_operations_struct drm_gem_shmem_vm_ops = {
442 .fault = drm_gem_shmem_fault,
443 .open = drm_gem_shmem_vm_open,
444 .close = drm_gem_shmem_vm_close,
446 EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
449 * drm_gem_shmem_mmap - Memory-map a shmem GEM object
451 * @vma: VMA for the area to be mapped
453 * This function implements an augmented version of the GEM DRM file mmap
454 * operation for shmem objects. Drivers which employ the shmem helpers should
455 * use this function as their &file_operations.mmap handler in the DRM device file's
456 * file_operations structure.
458 * Instead of directly referencing this function, drivers should use the
459 * DEFINE_DRM_GEM_SHMEM_FOPS() macro.
462 * 0 on success or a negative error code on failure.
464 int drm_gem_shmem_mmap(struct file *filp, struct vm_area_struct *vma)
466 struct drm_gem_shmem_object *shmem;
469 ret = drm_gem_mmap(filp, vma);
473 shmem = to_drm_gem_shmem_obj(vma->vm_private_data);
475 ret = drm_gem_shmem_get_pages(shmem);
477 drm_gem_vm_close(vma);
481 /* VM_PFNMAP was set by drm_gem_mmap() */
482 vma->vm_flags &= ~VM_PFNMAP;
483 vma->vm_flags |= VM_MIXEDMAP;
485 /* Remove the fake offset */
486 vma->vm_pgoff -= drm_vma_node_start(&shmem->base.vma_node);
490 EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
493 * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
495 * @indent: Tab indentation level
498 void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
499 const struct drm_gem_object *obj)
501 const struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
503 drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
504 drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
505 drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
507 EXPORT_SYMBOL(drm_gem_shmem_print_info);
510 * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
511 * pages for a shmem GEM object
514 * This function exports a scatter/gather table suitable for PRIME usage by
515 * calling the standard DMA mapping API.
518 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
520 struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
522 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
524 return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
526 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
529 * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
530 * scatter/gather table for a shmem GEM object.
533 * This function returns a scatter/gather table suitable for driver usage. If
534 * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
538 * A pointer to the scatter/gather table of pinned pages or errno on failure.
540 struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
543 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
544 struct sg_table *sgt;
549 WARN_ON(obj->import_attach);
551 ret = drm_gem_shmem_get_pages(shmem);
555 sgt = drm_gem_shmem_get_sg_table(&shmem->base);
560 /* Map the pages for use by the h/w. */
561 dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL);
568 drm_gem_shmem_put_pages(shmem);
571 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
574 * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
575 * another driver's scatter/gather table of pinned pages
576 * @dev: Device to import into
577 * @attach: DMA-BUF attachment
578 * @sgt: Scatter/gather table of pinned pages
580 * This function imports a scatter/gather table exported via DMA-BUF by
581 * another driver. Drivers that use the shmem helpers should set this as their
582 * &drm_driver.gem_prime_import_sg_table callback.
585 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
586 * error code on failure.
588 struct drm_gem_object *
589 drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
590 struct dma_buf_attachment *attach,
591 struct sg_table *sgt)
593 size_t size = PAGE_ALIGN(attach->dmabuf->size);
594 size_t npages = size >> PAGE_SHIFT;
595 struct drm_gem_shmem_object *shmem;
598 shmem = drm_gem_shmem_create(dev, size);
600 return ERR_CAST(shmem);
602 shmem->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
608 ret = drm_prime_sg_to_page_addr_arrays(sgt, shmem->pages, NULL, npages);
613 shmem->pages_use_count = 1; /* Permanently pinned from our point of view */
615 DRM_DEBUG_PRIME("size = %zu\n", size);
620 kvfree(shmem->pages);
622 drm_gem_object_put_unlocked(&shmem->base);
626 EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);