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.
27 static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
28 .free = drm_gem_shmem_free_object,
29 .print_info = drm_gem_shmem_print_info,
30 .pin = drm_gem_shmem_pin,
31 .unpin = drm_gem_shmem_unpin,
32 .get_sg_table = drm_gem_shmem_get_sg_table,
33 .vmap = drm_gem_shmem_vmap,
34 .vunmap = drm_gem_shmem_vunmap,
35 .vm_ops = &drm_gem_shmem_vm_ops,
39 * drm_gem_shmem_create - Allocate an object with the given size
41 * @size: Size of the object to allocate
43 * This function creates a shmem GEM object.
46 * A struct drm_gem_shmem_object * on success or an ERR_PTR()-encoded negative
47 * error code on failure.
49 struct drm_gem_shmem_object *drm_gem_shmem_create(struct drm_device *dev, size_t size)
51 struct drm_gem_shmem_object *shmem;
52 struct drm_gem_object *obj;
55 size = PAGE_ALIGN(size);
57 if (dev->driver->gem_create_object)
58 obj = dev->driver->gem_create_object(dev, size);
60 obj = kzalloc(sizeof(*shmem), GFP_KERNEL);
62 return ERR_PTR(-ENOMEM);
65 obj->funcs = &drm_gem_shmem_funcs;
67 ret = drm_gem_object_init(dev, obj, size);
71 ret = drm_gem_create_mmap_offset(obj);
75 shmem = to_drm_gem_shmem_obj(obj);
76 mutex_init(&shmem->pages_lock);
77 mutex_init(&shmem->vmap_lock);
80 * Our buffers are kept pinned, so allocating them
81 * from the MOVABLE zone is a really bad idea, and
82 * conflicts with CMA. See comments above new_inode()
83 * why this is required _and_ expected if you're
84 * going to pin these pages.
86 mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER |
87 __GFP_RETRY_MAYFAIL | __GFP_NOWARN);
92 drm_gem_object_release(obj);
98 EXPORT_SYMBOL_GPL(drm_gem_shmem_create);
101 * drm_gem_shmem_free_object - Free resources associated with a shmem GEM object
102 * @obj: GEM object to free
104 * This function cleans up the GEM object state and frees the memory used to
105 * store the object itself.
107 void drm_gem_shmem_free_object(struct drm_gem_object *obj)
109 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
111 WARN_ON(shmem->vmap_use_count);
113 if (obj->import_attach) {
114 shmem->pages_use_count--;
115 drm_prime_gem_destroy(obj, shmem->sgt);
116 kvfree(shmem->pages);
119 dma_unmap_sg(obj->dev->dev, shmem->sgt->sgl,
120 shmem->sgt->nents, DMA_BIDIRECTIONAL);
122 drm_gem_shmem_put_pages(shmem);
123 sg_free_table(shmem->sgt);
128 WARN_ON(shmem->pages_use_count);
130 drm_gem_object_release(obj);
131 mutex_destroy(&shmem->pages_lock);
132 mutex_destroy(&shmem->vmap_lock);
135 EXPORT_SYMBOL_GPL(drm_gem_shmem_free_object);
137 static int drm_gem_shmem_get_pages_locked(struct drm_gem_shmem_object *shmem)
139 struct drm_gem_object *obj = &shmem->base;
142 if (shmem->pages_use_count++ > 0)
145 pages = drm_gem_get_pages(obj);
147 DRM_DEBUG_KMS("Failed to get pages (%ld)\n", PTR_ERR(pages));
148 shmem->pages_use_count = 0;
149 return PTR_ERR(pages);
152 shmem->pages = pages;
158 * drm_gem_shmem_get_pages - Allocate backing pages for a shmem GEM object
159 * @shmem: shmem GEM object
161 * This function makes sure that backing pages exists for the shmem GEM object
162 * and increases the use count.
165 * 0 on success or a negative error code on failure.
167 int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem)
171 ret = mutex_lock_interruptible(&shmem->pages_lock);
174 ret = drm_gem_shmem_get_pages_locked(shmem);
175 mutex_unlock(&shmem->pages_lock);
179 EXPORT_SYMBOL(drm_gem_shmem_get_pages);
181 static void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem)
183 struct drm_gem_object *obj = &shmem->base;
185 if (WARN_ON_ONCE(!shmem->pages_use_count))
188 if (--shmem->pages_use_count > 0)
191 drm_gem_put_pages(obj, shmem->pages,
192 shmem->pages_mark_dirty_on_put,
193 shmem->pages_mark_accessed_on_put);
198 * drm_gem_shmem_put_pages - Decrease use count on the backing pages for a shmem GEM object
199 * @shmem: shmem GEM object
201 * This function decreases the use count and puts the backing pages when use drops to zero.
203 void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem)
205 mutex_lock(&shmem->pages_lock);
206 drm_gem_shmem_put_pages_locked(shmem);
207 mutex_unlock(&shmem->pages_lock);
209 EXPORT_SYMBOL(drm_gem_shmem_put_pages);
212 * drm_gem_shmem_pin - Pin backing pages for a shmem GEM object
215 * This function makes sure the backing pages are pinned in memory while the
216 * buffer is exported.
219 * 0 on success or a negative error code on failure.
221 int drm_gem_shmem_pin(struct drm_gem_object *obj)
223 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
225 return drm_gem_shmem_get_pages(shmem);
227 EXPORT_SYMBOL(drm_gem_shmem_pin);
230 * drm_gem_shmem_unpin - Unpin backing pages for a shmem GEM object
233 * This function removes the requirement that the backing pages are pinned in
236 void drm_gem_shmem_unpin(struct drm_gem_object *obj)
238 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
240 drm_gem_shmem_put_pages(shmem);
242 EXPORT_SYMBOL(drm_gem_shmem_unpin);
244 static void *drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem)
246 struct drm_gem_object *obj = &shmem->base;
249 if (shmem->vmap_use_count++ > 0)
252 ret = drm_gem_shmem_get_pages(shmem);
256 if (obj->import_attach)
257 shmem->vaddr = dma_buf_vmap(obj->import_attach->dmabuf);
259 shmem->vaddr = vmap(shmem->pages, obj->size >> PAGE_SHIFT,
260 VM_MAP, pgprot_writecombine(PAGE_KERNEL));
263 DRM_DEBUG_KMS("Failed to vmap pages\n");
271 drm_gem_shmem_put_pages(shmem);
273 shmem->vmap_use_count = 0;
279 * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
280 * @shmem: shmem GEM object
282 * This function makes sure that a virtual address exists for the buffer backing
283 * the shmem GEM object.
286 * 0 on success or a negative error code on failure.
288 void *drm_gem_shmem_vmap(struct drm_gem_object *obj)
290 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
294 ret = mutex_lock_interruptible(&shmem->vmap_lock);
297 vaddr = drm_gem_shmem_vmap_locked(shmem);
298 mutex_unlock(&shmem->vmap_lock);
302 EXPORT_SYMBOL(drm_gem_shmem_vmap);
304 static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem)
306 struct drm_gem_object *obj = &shmem->base;
308 if (WARN_ON_ONCE(!shmem->vmap_use_count))
311 if (--shmem->vmap_use_count > 0)
314 if (obj->import_attach)
315 dma_buf_vunmap(obj->import_attach->dmabuf, shmem->vaddr);
317 vunmap(shmem->vaddr);
320 drm_gem_shmem_put_pages(shmem);
324 * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
325 * @shmem: shmem GEM object
327 * This function removes the virtual address when use count drops to zero.
329 void drm_gem_shmem_vunmap(struct drm_gem_object *obj, void *vaddr)
331 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
333 mutex_lock(&shmem->vmap_lock);
334 drm_gem_shmem_vunmap_locked(shmem);
335 mutex_unlock(&shmem->vmap_lock);
337 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
339 struct drm_gem_shmem_object *
340 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
341 struct drm_device *dev, size_t size,
344 struct drm_gem_shmem_object *shmem;
347 shmem = drm_gem_shmem_create(dev, size);
352 * Allocate an id of idr table where the obj is registered
353 * and handle has the id what user can see.
355 ret = drm_gem_handle_create(file_priv, &shmem->base, handle);
356 /* drop reference from allocate - handle holds it now. */
357 drm_gem_object_put_unlocked(&shmem->base);
363 EXPORT_SYMBOL(drm_gem_shmem_create_with_handle);
366 * drm_gem_shmem_dumb_create - Create a dumb shmem buffer object
367 * @file: DRM file structure to create the dumb buffer for
371 * This function computes the pitch of the dumb buffer and rounds it up to an
372 * integer number of bytes per pixel. Drivers for hardware that doesn't have
373 * any additional restrictions on the pitch can directly use this function as
374 * their &drm_driver.dumb_create callback.
376 * For hardware with additional restrictions, drivers can adjust the fields
377 * set up by userspace before calling into this function.
380 * 0 on success or a negative error code on failure.
382 int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev,
383 struct drm_mode_create_dumb *args)
385 u32 min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
386 struct drm_gem_shmem_object *shmem;
388 if (!args->pitch || !args->size) {
389 args->pitch = min_pitch;
390 args->size = args->pitch * args->height;
392 /* ensure sane minimum values */
393 if (args->pitch < min_pitch)
394 args->pitch = min_pitch;
395 if (args->size < args->pitch * args->height)
396 args->size = args->pitch * args->height;
399 shmem = drm_gem_shmem_create_with_handle(file, dev, args->size, &args->handle);
401 return PTR_ERR_OR_ZERO(shmem);
403 EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create);
405 static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf)
407 struct vm_area_struct *vma = vmf->vma;
408 struct drm_gem_object *obj = vma->vm_private_data;
409 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
410 loff_t num_pages = obj->size >> PAGE_SHIFT;
413 if (vmf->pgoff >= num_pages || WARN_ON_ONCE(!shmem->pages))
414 return VM_FAULT_SIGBUS;
416 page = shmem->pages[vmf->pgoff];
418 return vmf_insert_page(vma, vmf->address, page);
421 static void drm_gem_shmem_vm_open(struct vm_area_struct *vma)
423 struct drm_gem_object *obj = vma->vm_private_data;
424 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
427 ret = drm_gem_shmem_get_pages(shmem);
428 WARN_ON_ONCE(ret != 0);
430 drm_gem_vm_open(vma);
433 static void drm_gem_shmem_vm_close(struct vm_area_struct *vma)
435 struct drm_gem_object *obj = vma->vm_private_data;
436 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
438 drm_gem_shmem_put_pages(shmem);
439 drm_gem_vm_close(vma);
442 const struct vm_operations_struct drm_gem_shmem_vm_ops = {
443 .fault = drm_gem_shmem_fault,
444 .open = drm_gem_shmem_vm_open,
445 .close = drm_gem_shmem_vm_close,
447 EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops);
450 * drm_gem_shmem_mmap - Memory-map a shmem GEM object
452 * @vma: VMA for the area to be mapped
454 * This function implements an augmented version of the GEM DRM file mmap
455 * operation for shmem objects. Drivers which employ the shmem helpers should
456 * use this function as their &file_operations.mmap handler in the DRM device file's
457 * file_operations structure.
459 * Instead of directly referencing this function, drivers should use the
460 * DEFINE_DRM_GEM_SHMEM_FOPS() macro.
463 * 0 on success or a negative error code on failure.
465 int drm_gem_shmem_mmap(struct file *filp, struct vm_area_struct *vma)
467 struct drm_gem_shmem_object *shmem;
470 ret = drm_gem_mmap(filp, vma);
474 shmem = to_drm_gem_shmem_obj(vma->vm_private_data);
476 ret = drm_gem_shmem_get_pages(shmem);
478 drm_gem_vm_close(vma);
482 /* VM_PFNMAP was set by drm_gem_mmap() */
483 vma->vm_flags &= ~VM_PFNMAP;
484 vma->vm_flags |= VM_MIXEDMAP;
486 /* Remove the fake offset */
487 vma->vm_pgoff -= drm_vma_node_start(&shmem->base.vma_node);
491 EXPORT_SYMBOL_GPL(drm_gem_shmem_mmap);
494 * drm_gem_shmem_print_info() - Print &drm_gem_shmem_object info for debugfs
496 * @indent: Tab indentation level
499 void drm_gem_shmem_print_info(struct drm_printer *p, unsigned int indent,
500 const struct drm_gem_object *obj)
502 const struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
504 drm_printf_indent(p, indent, "pages_use_count=%u\n", shmem->pages_use_count);
505 drm_printf_indent(p, indent, "vmap_use_count=%u\n", shmem->vmap_use_count);
506 drm_printf_indent(p, indent, "vaddr=%p\n", shmem->vaddr);
508 EXPORT_SYMBOL(drm_gem_shmem_print_info);
511 * drm_gem_shmem_get_sg_table - Provide a scatter/gather table of pinned
512 * pages for a shmem GEM object
515 * This function exports a scatter/gather table suitable for PRIME usage by
516 * calling the standard DMA mapping API.
519 * A pointer to the scatter/gather table of pinned pages or NULL on failure.
521 struct sg_table *drm_gem_shmem_get_sg_table(struct drm_gem_object *obj)
523 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
525 return drm_prime_pages_to_sg(shmem->pages, obj->size >> PAGE_SHIFT);
527 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_sg_table);
530 * drm_gem_shmem_get_pages_sgt - Pin pages, dma map them, and return a
531 * scatter/gather table for a shmem GEM object.
534 * This function returns a scatter/gather table suitable for driver usage. If
535 * the sg table doesn't exist, the pages are pinned, dma-mapped, and a sg
539 * A pointer to the scatter/gather table of pinned pages or errno on failure.
541 struct sg_table *drm_gem_shmem_get_pages_sgt(struct drm_gem_object *obj)
544 struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
545 struct sg_table *sgt;
550 WARN_ON(obj->import_attach);
552 ret = drm_gem_shmem_get_pages(shmem);
556 sgt = drm_gem_shmem_get_sg_table(&shmem->base);
561 /* Map the pages for use by the h/w. */
562 dma_map_sg(obj->dev->dev, sgt->sgl, sgt->nents, DMA_BIDIRECTIONAL);
569 drm_gem_shmem_put_pages(shmem);
572 EXPORT_SYMBOL_GPL(drm_gem_shmem_get_pages_sgt);
575 * drm_gem_shmem_prime_import_sg_table - Produce a shmem GEM object from
576 * another driver's scatter/gather table of pinned pages
577 * @dev: Device to import into
578 * @attach: DMA-BUF attachment
579 * @sgt: Scatter/gather table of pinned pages
581 * This function imports a scatter/gather table exported via DMA-BUF by
582 * another driver. Drivers that use the shmem helpers should set this as their
583 * &drm_driver.gem_prime_import_sg_table callback.
586 * A pointer to a newly created GEM object or an ERR_PTR-encoded negative
587 * error code on failure.
589 struct drm_gem_object *
590 drm_gem_shmem_prime_import_sg_table(struct drm_device *dev,
591 struct dma_buf_attachment *attach,
592 struct sg_table *sgt)
594 size_t size = PAGE_ALIGN(attach->dmabuf->size);
595 size_t npages = size >> PAGE_SHIFT;
596 struct drm_gem_shmem_object *shmem;
599 shmem = drm_gem_shmem_create(dev, size);
601 return ERR_CAST(shmem);
603 shmem->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
609 ret = drm_prime_sg_to_page_addr_arrays(sgt, shmem->pages, NULL, npages);
614 shmem->pages_use_count = 1; /* Permanently pinned from our point of view */
616 DRM_DEBUG_PRIME("size = %zu\n", size);
621 kvfree(shmem->pages);
623 drm_gem_object_put_unlocked(&shmem->base);
627 EXPORT_SYMBOL_GPL(drm_gem_shmem_prime_import_sg_table);