/* * Copyright © 2012 Red Hat * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. * * Authors: * Dave Airlie <[email protected]> * Rob Clark <[email protected]> * */ #include <linux/export.h> #include <linux/dma-buf.h> #include <linux/rbtree.h> #include <linux/module.h> #include <drm/drm.h> #include <drm/drm_drv.h> #include <drm/drm_file.h> #include <drm/drm_framebuffer.h> #include <drm/drm_gem.h> #include <drm/drm_prime.h> #include "drm_internal.h" MODULE_IMPORT_NS(…); /** * DOC: overview and lifetime rules * * Similar to GEM global names, PRIME file descriptors are also used to share * buffer objects across processes. They offer additional security: as file * descriptors must be explicitly sent over UNIX domain sockets to be shared * between applications, they can't be guessed like the globally unique GEM * names. * * Drivers that support the PRIME API implement the drm_gem_object_funcs.export * and &drm_driver.gem_prime_import hooks. &dma_buf_ops implementations for * drivers are all individually exported for drivers which need to overwrite * or reimplement some of them. * * Reference Counting for GEM Drivers * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * * On the export the &dma_buf holds a reference to the exported buffer object, * usually a &drm_gem_object. It takes this reference in the PRIME_HANDLE_TO_FD * IOCTL, when it first calls &drm_gem_object_funcs.export * and stores the exporting GEM object in the &dma_buf.priv field. This * reference needs to be released when the final reference to the &dma_buf * itself is dropped and its &dma_buf_ops.release function is called. For * GEM-based drivers, the &dma_buf should be exported using * drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release(). * * Thus the chain of references always flows in one direction, avoiding loops: * importing GEM object -> dma-buf -> exported GEM bo. A further complication * are the lookup caches for import and export. These are required to guarantee * that any given object will always have only one unique userspace handle. This * is required to allow userspace to detect duplicated imports, since some GEM * drivers do fail command submissions if a given buffer object is listed more * than once. These import and export caches in &drm_prime_file_private only * retain a weak reference, which is cleaned up when the corresponding object is * released. * * Self-importing: If userspace is using PRIME as a replacement for flink then * it will get a fd->handle request for a GEM object that it created. Drivers * should detect this situation and return back the underlying object from the * dma-buf private. For GEM based drivers this is handled in * drm_gem_prime_import() already. */ struct drm_prime_member { … }; static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t handle) { … } static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv, uint32_t handle) { … } static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv, struct dma_buf *dma_buf, uint32_t *handle) { … } void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv, uint32_t handle) { … } void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv) { … } void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv) { … } /** * drm_gem_dmabuf_export - &dma_buf export implementation for GEM * @dev: parent device for the exported dmabuf * @exp_info: the export information used by dma_buf_export() * * This wraps dma_buf_export() for use by generic GEM drivers that are using * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take * a reference to the &drm_device and the exported &drm_gem_object (stored in * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release(). * * Returns the new dmabuf. */ struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev, struct dma_buf_export_info *exp_info) { … } EXPORT_SYMBOL(…); /** * drm_gem_dmabuf_release - &dma_buf release implementation for GEM * @dma_buf: buffer to be released * * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers * must use this in their &dma_buf_ops structure as the release callback. * drm_gem_dmabuf_release() should be used in conjunction with * drm_gem_dmabuf_export(). */ void drm_gem_dmabuf_release(struct dma_buf *dma_buf) { … } EXPORT_SYMBOL(…); /** * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers * @dev: drm_device to import into * @file_priv: drm file-private structure * @prime_fd: fd id of the dma-buf which should be imported * @handle: pointer to storage for the handle of the imported buffer object * * This is the PRIME import function which must be used mandatorily by GEM * drivers to ensure correct lifetime management of the underlying GEM object. * The actual importing of GEM object from the dma-buf is done through the * &drm_driver.gem_prime_import driver callback. * * Returns 0 on success or a negative error code on failure. */ int drm_gem_prime_fd_to_handle(struct drm_device *dev, struct drm_file *file_priv, int prime_fd, uint32_t *handle) { … } EXPORT_SYMBOL(…); int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } static struct dma_buf *export_and_register_object(struct drm_device *dev, struct drm_gem_object *obj, uint32_t flags) { … } /** * drm_gem_prime_handle_to_dmabuf - PRIME export function for GEM drivers * @dev: dev to export the buffer from * @file_priv: drm file-private structure * @handle: buffer handle to export * @flags: flags like DRM_CLOEXEC * * This is the PRIME export function which must be used mandatorily by GEM * drivers to ensure correct lifetime management of the underlying GEM object. * The actual exporting from GEM object to a dma-buf is done through the * &drm_gem_object_funcs.export callback. * * Unlike drm_gem_prime_handle_to_fd(), it returns the struct dma_buf it * has created, without attaching it to any file descriptors. The difference * between those two is similar to that between anon_inode_getfile() and * anon_inode_getfd(); insertion into descriptor table is something you * can not revert if any cleanup is needed, so the descriptor-returning * variants should only be used when you are past the last failure exit * and the only thing left is passing the new file descriptor to userland. * When all you need is the object itself or when you need to do something * else that might fail, use that one instead. */ struct dma_buf *drm_gem_prime_handle_to_dmabuf(struct drm_device *dev, struct drm_file *file_priv, uint32_t handle, uint32_t flags) { … } EXPORT_SYMBOL(…); /** * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers * @dev: dev to export the buffer from * @file_priv: drm file-private structure * @handle: buffer handle to export * @flags: flags like DRM_CLOEXEC * @prime_fd: pointer to storage for the fd id of the create dma-buf * * This is the PRIME export function which must be used mandatorily by GEM * drivers to ensure correct lifetime management of the underlying GEM object. * The actual exporting from GEM object to a dma-buf is done through the * &drm_gem_object_funcs.export callback. */ int drm_gem_prime_handle_to_fd(struct drm_device *dev, struct drm_file *file_priv, uint32_t handle, uint32_t flags, int *prime_fd) { … } EXPORT_SYMBOL(…); int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv) { … } /** * DOC: PRIME Helpers * * Drivers can implement &drm_gem_object_funcs.export and * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions * implement dma-buf support in terms of some lower-level helpers, which are * again exported for drivers to use individually: * * Exporting buffers * ~~~~~~~~~~~~~~~~~ * * Optional pinning of buffers is handled at dma-buf attach and detach time in * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on * &drm_gem_object_funcs.get_sg_table. If &drm_gem_object_funcs.get_sg_table is * unimplemented, exports into another device are rejected. * * For kernel-internal access there's drm_gem_dmabuf_vmap() and * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by * drm_gem_dmabuf_mmap(). * * Note that these export helpers can only be used if the underlying backing * storage is fully coherent and either permanently pinned, or it is safe to pin * it indefinitely. * * FIXME: The underlying helper functions are named rather inconsistently. * * Importing buffers * ~~~~~~~~~~~~~~~~~ * * Importing dma-bufs using drm_gem_prime_import() relies on * &drm_driver.gem_prime_import_sg_table. * * Note that similarly to the export helpers this permanently pins the * underlying backing storage. Which is ok for scanout, but is not the best * option for sharing lots of buffers for rendering. */ /** * drm_gem_map_attach - dma_buf attach implementation for GEM * @dma_buf: buffer to attach device to * @attach: buffer attachment data * * Calls &drm_gem_object_funcs.pin for device specific handling. This can be * used as the &dma_buf_ops.attach callback. Must be used together with * drm_gem_map_detach(). * * Returns 0 on success, negative error code on failure. */ int drm_gem_map_attach(struct dma_buf *dma_buf, struct dma_buf_attachment *attach) { … } EXPORT_SYMBOL(…); /** * drm_gem_map_detach - dma_buf detach implementation for GEM * @dma_buf: buffer to detach from * @attach: attachment to be detached * * Calls &drm_gem_object_funcs.pin for device specific handling. Cleans up * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the * &dma_buf_ops.detach callback. */ void drm_gem_map_detach(struct dma_buf *dma_buf, struct dma_buf_attachment *attach) { … } EXPORT_SYMBOL(…); /** * drm_gem_map_dma_buf - map_dma_buf implementation for GEM * @attach: attachment whose scatterlist is to be returned * @dir: direction of DMA transfer * * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together * with drm_gem_unmap_dma_buf(). * * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR * on error. May return -EINTR if it is interrupted by a signal. */ struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach, enum dma_data_direction dir) { … } EXPORT_SYMBOL(…); /** * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM * @attach: attachment to unmap buffer from * @sgt: scatterlist info of the buffer to unmap * @dir: direction of DMA transfer * * This can be used as the &dma_buf_ops.unmap_dma_buf callback. */ void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach, struct sg_table *sgt, enum dma_data_direction dir) { … } EXPORT_SYMBOL(…); /** * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM * @dma_buf: buffer to be mapped * @map: the virtual address of the buffer * * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling. * The kernel virtual address is returned in map. * * Returns 0 on success or a negative errno code otherwise. */ int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct iosys_map *map) { … } EXPORT_SYMBOL(…); /** * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM * @dma_buf: buffer to be unmapped * @map: the virtual address of the buffer * * Releases a kernel virtual mapping. This can be used as the * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling. */ void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct iosys_map *map) { … } EXPORT_SYMBOL(…); /** * drm_gem_prime_mmap - PRIME mmap function for GEM drivers * @obj: GEM object * @vma: Virtual address range * * This function sets up a userspace mapping for PRIME exported buffers using * the same codepath that is used for regular GEM buffer mapping on the DRM fd. * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is * called to set up the mapping. */ int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) { … } EXPORT_SYMBOL(…); /** * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM * @dma_buf: buffer to be mapped * @vma: virtual address range * * Provides memory mapping for the buffer. This can be used as the * &dma_buf_ops.mmap callback. It just forwards to drm_gem_prime_mmap(). * * Returns 0 on success or a negative error code on failure. */ int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma) { … } EXPORT_SYMBOL(…); static const struct dma_buf_ops drm_gem_prime_dmabuf_ops = …; /** * drm_prime_pages_to_sg - converts a page array into an sg list * @dev: DRM device * @pages: pointer to the array of page pointers to convert * @nr_pages: length of the page vector * * This helper creates an sg table object from a set of pages * the driver is responsible for mapping the pages into the * importers address space for use with dma_buf itself. * * This is useful for implementing &drm_gem_object_funcs.get_sg_table. */ struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev, struct page **pages, unsigned int nr_pages) { … } EXPORT_SYMBOL(…); /** * drm_prime_get_contiguous_size - returns the contiguous size of the buffer * @sgt: sg_table describing the buffer to check * * This helper calculates the contiguous size in the DMA address space * of the buffer described by the provided sg_table. * * This is useful for implementing * &drm_gem_object_funcs.gem_prime_import_sg_table. */ unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt) { … } EXPORT_SYMBOL(…); /** * drm_gem_prime_export - helper library implementation of the export callback * @obj: GEM object to export * @flags: flags like DRM_CLOEXEC and DRM_RDWR * * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers * using the PRIME helpers. It is used as the default in * drm_gem_prime_handle_to_fd(). */ struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj, int flags) { … } EXPORT_SYMBOL(…); /** * drm_gem_prime_import_dev - core implementation of the import callback * @dev: drm_device to import into * @dma_buf: dma-buf object to import * @attach_dev: struct device to dma_buf attach * * This is the core of drm_gem_prime_import(). It's designed to be called by * drivers who want to use a different device structure than &drm_device.dev for * attaching via dma_buf. This function calls * &drm_driver.gem_prime_import_sg_table internally. * * Drivers must arrange to call drm_prime_gem_destroy() from their * &drm_gem_object_funcs.free hook when using this function. */ struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev, struct dma_buf *dma_buf, struct device *attach_dev) { … } EXPORT_SYMBOL(…); /** * drm_gem_prime_import - helper library implementation of the import callback * @dev: drm_device to import into * @dma_buf: dma-buf object to import * * This is the implementation of the gem_prime_import functions for GEM drivers * using the PRIME helpers. Drivers can use this as their * &drm_driver.gem_prime_import implementation. It is used as the default * implementation in drm_gem_prime_fd_to_handle(). * * Drivers must arrange to call drm_prime_gem_destroy() from their * &drm_gem_object_funcs.free hook when using this function. */ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev, struct dma_buf *dma_buf) { … } EXPORT_SYMBOL(…); /** * drm_prime_sg_to_page_array - convert an sg table into a page array * @sgt: scatter-gather table to convert * @pages: array of page pointers to store the pages in * @max_entries: size of the passed-in array * * Exports an sg table into an array of pages. * * This function is deprecated and strongly discouraged to be used. * The page array is only useful for page faults and those can corrupt fields * in the struct page if they are not handled by the exporting driver. */ int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt, struct page **pages, int max_entries) { … } EXPORT_SYMBOL(…); /** * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array * @sgt: scatter-gather table to convert * @addrs: array to store the dma bus address of each page * @max_entries: size of both the passed-in arrays * * Exports an sg table into an array of addresses. * * Drivers should use this in their &drm_driver.gem_prime_import_sg_table * implementation. */ int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs, int max_entries) { … } EXPORT_SYMBOL(…); /** * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object * @obj: GEM object which was created from a dma-buf * @sg: the sg-table which was pinned at import time * * This is the cleanup functions which GEM drivers need to call when they use * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs. */ void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg) { … } EXPORT_SYMBOL(…);
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