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, VM_MAP, PAGE_KERNEL);
261 DRM_DEBUG_KMS("Failed to vmap pages\n");
269 drm_gem_shmem_put_pages(shmem);
271 shmem->vmap_use_count = 0;
277 * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
278 * @shmem: shmem GEM object
280 * This function makes sure that a virtual address exists for the buffer backing
281 * the shmem GEM object.
284 * 0 on success or a negative error code on failure.
286 void *drm_gem_shmem_vmap(struct drm_gem_object *obj)
288 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
292 ret = mutex_lock_interruptible(&shmem->vmap_lock);
295 vaddr = drm_gem_shmem_vmap_locked(shmem);
296 mutex_unlock(&shmem->vmap_lock);
300 EXPORT_SYMBOL(drm_gem_shmem_vmap);
302 static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem)
304 struct drm_gem_object *obj = &shmem->base;
306 if (WARN_ON_ONCE(!shmem->vmap_use_count))
309 if (--shmem->vmap_use_count > 0)
312 if (obj->import_attach)
313 dma_buf_vunmap(obj->import_attach->dmabuf, shmem->vaddr);
315 vunmap(shmem->vaddr);
318 drm_gem_shmem_put_pages(shmem);
322 * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
323 * @shmem: shmem GEM object
325 * This function removes the virtual address when use count drops to zero.
327 void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr)
329 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
331 mutex_lock(&shmem->vmap_lock);
332 drm_gem_shmem_vunmap_locked(shmem);
333 mutex_unlock(&shmem->vmap_lock);
335 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
337 struct drm_gem_shmem_object *
338 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
339 struct drm_device *dev, size_t size,
342 struct drm_gem_shmem_object *shmem;
345 shmem = drm_gem_shmem_create(dev, size);
350 * Allocate an id of idr table where the obj is registered
351 * and handle has the id what user can see.
353 ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
354 /* drop reference from allocate - handle holds it now. */
355 drm_gem_object_put_unlocked(&shmem->base);
361 EXPORT_SYMBOL(drm_gem_shmem_create_with_handle);
364 * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
365 * @file: DRM file structure to create the dumb buffer for
369 * This function computes the pitch of the dumb buffer and rounds it up to an
370 * integer number of bytes per pixel. Drivers for hardware that doesn't have
371 * any additional restrictions on the pitch can directly use this function as
372 * their &drm_driver.dumb_create callback.
374 * For hardware with additional restrictions, drivers can adjust the fields
375 * set up by userspace before calling into this function.
378 * 0 on success or a negative error code on failure.
380 int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
381 struct drm_mode_create_dumb *args)
383 u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
384 struct drm_gem_shmem_object *shmem;
386 if (!args->pitch || !args->size) {
387 args->pitch = min_pitch;
388 args->size = args->pitch * args->height;
390 /* ensure sane minimum values */
391 if (args->pitch < min_pitch)
392 args->pitch = min_pitch;
393 if (args->size < args->pitch * args->height)
394 args->size = args->pitch * args->height;
397 shmem = drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
399 return PTR_ERR_OR_ZERO(shmem);
401 EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
403 static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
405 struct vm_area_struct *vma = vmf->vma;
406 struct drm_gem_object *obj = vma->vm_private_data;
407 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
408 loff_t num_pages = obj->size >> PAGE_SHIFT;
411 if (vmf->pgoff >= num_pages || WARN_ON_ONCE(!shmem->pages))
412 return VM_FAULT_SIGBUS;
414 page = shmem->pages[vmf->pgoff];
416 return vmf_insert_page(vma, vmf->address, page);
419 static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
421 struct drm_gem_object *obj = vma->vm_private_data;
422 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
425 ret = drm_gem_shmem_get_pages(shmem);
426 WARN_ON_ONCE(ret != 0);
428 drm_gem_vm_open(vma);
431 static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
433 struct drm_gem_object *obj = vma->vm_private_data;
434 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
436 drm_gem_shmem_put_pages(shmem);
437 drm_gem_vm_close(vma);
440 const struct vm_operations_struct drm_gem_shmem_vm_ops = {
441 .fault = drm_gem_shmem_fault,
442 .open = drm_gem_shmem_vm_open,
443 .close = drm_gem_shmem_vm_close,
445 EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
448 * drm_gem_shmem_mmap - Memory-map a shmem GEM object
450 * @vma: VMA for the area to be mapped
452 * This function implements an augmented version of the GEM DRM file mmap
453 * operation for shmem objects. Drivers which employ the shmem helpers should
454 * use this function as their &file_operations.mmap handler in the DRM device file's
455 * file_operations structure.
457 * Instead of directly referencing this function, drivers should use the
458 * DEFINE_DRM_GEM_SHMEM_FOPS() macro.
461 * 0 on success or a negative error code on failure.
463 int drm_gem_shmem_mmap(struct file *filp, struct vm_area_struct *vma)
465 struct drm_gem_shmem_object *shmem;
468 ret = drm_gem_mmap(filp, vma);
472 shmem = to_drm_gem_shmem_obj(vma->vm_private_data);
474 ret = drm_gem_shmem_get_pages(shmem);
476 drm_gem_vm_close(vma);
480 /* VM_PFNMAP was set by drm_gem_mmap() */
481 vma->vm_flags &= ~VM_PFNMAP;
482 vma->vm_flags |= VM_MIXEDMAP;
484 /* Remove the fake offset */
485 vma->vm_pgoff -= drm_vma_node_start(&shmem->base.vma_node);
489 EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
492 * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
494 * @indent: Tab indentation level
497 void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
498 const struct drm_gem_object *obj)
500 const struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
502 drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
503 drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
504 drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
506 EXPORT_SYMBOL(drm_gem_shmem_print_info);
509 * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
510 * pages for a shmem GEM object
513 * This function exports a scatter/gather table suitable for PRIME usage by
514 * calling the standard DMA mapping API.
517 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
519 struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
521 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
523 return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
525 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
528 * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
529 * scatter/gather table for a shmem GEM object.
532 * This function returns a scatter/gather table suitable for driver usage. If
533 * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
537 * A pointer to the scatter/gather table of pinned pages or errno on failure.
539 struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
542 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
543 struct sg_table *sgt;
548 WARN_ON(obj->import_attach);
550 ret = drm_gem_shmem_get_pages(shmem);
554 sgt = drm_gem_shmem_get_sg_table(&shmem->base);
559 /* Map the pages for use by the h/w. */
560 dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL);
567 drm_gem_shmem_put_pages(shmem);
570 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
573 * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
574 * another driver's scatter/gather table of pinned pages
575 * @dev: Device to import into
576 * @attach: DMA-BUF attachment
577 * @sgt: Scatter/gather table of pinned pages
579 * This function imports a scatter/gather table exported via DMA-BUF by
580 * another driver. Drivers that use the shmem helpers should set this as their
581 * &drm_driver.gem_prime_import_sg_table callback.
584 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
585 * error code on failure.
587 struct drm_gem_object *
588 drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
589 struct dma_buf_attachment *attach,
590 struct sg_table *sgt)
592 size_t size = PAGE_ALIGN(attach->dmabuf->size);
593 size_t npages = size >> PAGE_SHIFT;
594 struct drm_gem_shmem_object *shmem;
597 shmem = drm_gem_shmem_create(dev, size);
599 return ERR_CAST(shmem);
601 shmem->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
607 ret = drm_prime_sg_to_page_addr_arrays(sgt, shmem->pages, NULL, npages);
612 shmem->pages_use_count = 1; /* Permanently pinned from our point of view */
614 DRM_DEBUG_PRIME("size = %zu\n", size);
619 kvfree(shmem->pages);
621 drm_gem_object_put_unlocked(&shmem->base);
625 EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);