1/*
   2 * Copyright © 2012 Red Hat
   3 *
   4 * Permission is hereby granted, free of charge, to any person obtaining a
   5 * copy of this software and associated documentation files (the "Software"),
   6 * to deal in the Software without restriction, including without limitation
   7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8 * and/or sell copies of the Software, and to permit persons to whom the
   9 * Software is furnished to do so, subject to the following conditions:
  10 *
  11 * The above copyright notice and this permission notice (including the next
  12 * paragraph) shall be included in all copies or substantial portions of the
  13 * Software.
  14 *
  15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21 * IN THE SOFTWARE.
  22 *
  23 * Authors:
  24 *      Dave Airlie <airlied@redhat.com>
  25 *      Rob Clark <rob.clark@linaro.org>
  26 *
  27 */
  28
  29#include <linux/export.h>
  30#include <linux/dma-buf.h>
  31#include <linux/rbtree.h>
  32
  33#include <drm/drm.h>
  34#include <drm/drm_drv.h>
  35#include <drm/drm_file.h>
  36#include <drm/drm_framebuffer.h>
  37#include <drm/drm_gem.h>
  38#include <drm/drm_prime.h>
  39
  40#include "drm_internal.h"
  41
  42/**
  43 * DOC: overview and lifetime rules
  44 *
  45 * Similar to GEM global names, PRIME file descriptors are also used to share
  46 * buffer objects across processes. They offer additional security: as file
  47 * descriptors must be explicitly sent over UNIX domain sockets to be shared
  48 * between applications, they can't be guessed like the globally unique GEM
  49 * names.
  50 *
  51 * Drivers that support the PRIME API implement the
  52 * &drm_driver.prime_handle_to_fd and &drm_driver.prime_fd_to_handle operations.
  53 * GEM based drivers must use drm_gem_prime_handle_to_fd() and
  54 * drm_gem_prime_fd_to_handle() to implement these. For GEM based drivers the
  55 * actual driver interfaces is provided through the &drm_gem_object_funcs.export
  56 * and &drm_driver.gem_prime_import hooks.
  57 *
  58 * &dma_buf_ops implementations for GEM drivers are all individually exported
  59 * for drivers which need to overwrite or reimplement some of them.
  60 *
  61 * Reference Counting for GEM Drivers
  62 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  63 *
  64 * On the export the &dma_buf holds a reference to the exported buffer object,
  65 * usually a &drm_gem_object. It takes this reference in the PRIME_HANDLE_TO_FD
  66 * IOCTL, when it first calls &drm_gem_object_funcs.export
  67 * and stores the exporting GEM object in the &dma_buf.priv field. This
  68 * reference needs to be released when the final reference to the &dma_buf
  69 * itself is dropped and its &dma_buf_ops.release function is called.  For
  70 * GEM-based drivers, the &dma_buf should be exported using
  71 * drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release().
  72 *
  73 * Thus the chain of references always flows in one direction, avoiding loops:
  74 * importing GEM object -> dma-buf -> exported GEM bo. A further complication
  75 * are the lookup caches for import and export. These are required to guarantee
  76 * that any given object will always have only one uniqe userspace handle. This
  77 * is required to allow userspace to detect duplicated imports, since some GEM
  78 * drivers do fail command submissions if a given buffer object is listed more
  79 * than once. These import and export caches in &drm_prime_file_private only
  80 * retain a weak reference, which is cleaned up when the corresponding object is
  81 * released.
  82 *
  83 * Self-importing: If userspace is using PRIME as a replacement for flink then
  84 * it will get a fd->handle request for a GEM object that it created.  Drivers
  85 * should detect this situation and return back the underlying object from the
  86 * dma-buf private. For GEM based drivers this is handled in
  87 * drm_gem_prime_import() already.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  88 */
  89
  90struct drm_prime_member {
 
  91	struct dma_buf *dma_buf;
  92	uint32_t handle;
 
  93
  94	struct rb_node dmabuf_rb;
  95	struct rb_node handle_rb;
 
  96};
  97
  98static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
  99				    struct dma_buf *dma_buf, uint32_t handle)
 100{
 101	struct drm_prime_member *member;
 102	struct rb_node **p, *rb;
 103
 104	member = kmalloc(sizeof(*member), GFP_KERNEL);
 105	if (!member)
 106		return -ENOMEM;
 107
 108	get_dma_buf(dma_buf);
 109	member->dma_buf = dma_buf;
 110	member->handle = handle;
 111
 112	rb = NULL;
 113	p = &prime_fpriv->dmabufs.rb_node;
 114	while (*p) {
 115		struct drm_prime_member *pos;
 116
 117		rb = *p;
 118		pos = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
 119		if (dma_buf > pos->dma_buf)
 120			p = &rb->rb_right;
 121		else
 122			p = &rb->rb_left;
 123	}
 124	rb_link_node(&member->dmabuf_rb, rb, p);
 125	rb_insert_color(&member->dmabuf_rb, &prime_fpriv->dmabufs);
 126
 127	rb = NULL;
 128	p = &prime_fpriv->handles.rb_node;
 129	while (*p) {
 130		struct drm_prime_member *pos;
 131
 132		rb = *p;
 133		pos = rb_entry(rb, struct drm_prime_member, handle_rb);
 134		if (handle > pos->handle)
 135			p = &rb->rb_right;
 136		else
 137			p = &rb->rb_left;
 138	}
 139	rb_link_node(&member->handle_rb, rb, p);
 140	rb_insert_color(&member->handle_rb, &prime_fpriv->handles);
 141
 142	return 0;
 143}
 144
 145static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv,
 146						      uint32_t handle)
 147{
 148	struct rb_node *rb;
 149
 150	rb = prime_fpriv->handles.rb_node;
 151	while (rb) {
 152		struct drm_prime_member *member;
 153
 154		member = rb_entry(rb, struct drm_prime_member, handle_rb);
 155		if (member->handle == handle)
 156			return member->dma_buf;
 157		else if (member->handle < handle)
 158			rb = rb->rb_right;
 159		else
 160			rb = rb->rb_left;
 161	}
 162
 163	return NULL;
 164}
 165
 166static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv,
 167				       struct dma_buf *dma_buf,
 168				       uint32_t *handle)
 169{
 170	struct rb_node *rb;
 171
 172	rb = prime_fpriv->dmabufs.rb_node;
 173	while (rb) {
 174		struct drm_prime_member *member;
 175
 176		member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
 177		if (member->dma_buf == dma_buf) {
 178			*handle = member->handle;
 179			return 0;
 180		} else if (member->dma_buf < dma_buf) {
 181			rb = rb->rb_right;
 182		} else {
 183			rb = rb->rb_left;
 184		}
 185	}
 186
 187	return -ENOENT;
 188}
 189
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 190void drm_prime_remove_buf_handle_locked(struct drm_prime_file_private *prime_fpriv,
 191					struct dma_buf *dma_buf)
 192{
 193	struct rb_node *rb;
 194
 195	rb = prime_fpriv->dmabufs.rb_node;
 196	while (rb) {
 197		struct drm_prime_member *member;
 198
 199		member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
 200		if (member->dma_buf == dma_buf) {
 201			rb_erase(&member->handle_rb, &prime_fpriv->handles);
 202			rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs);
 203
 204			dma_buf_put(dma_buf);
 
 205			kfree(member);
 206			return;
 207		} else if (member->dma_buf < dma_buf) {
 208			rb = rb->rb_right;
 209		} else {
 210			rb = rb->rb_left;
 211		}
 212	}
 213}
 214
 215void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
 
 216{
 217	mutex_init(&prime_fpriv->lock);
 218	prime_fpriv->dmabufs = RB_ROOT;
 219	prime_fpriv->handles = RB_ROOT;
 220}
 221
 222void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
 223{
 224	/* by now drm_gem_release should've made sure the list is empty */
 225	WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
 226}
 227
 228/**
 229 * drm_gem_dmabuf_export - &dma_buf export implementation for GEM
 230 * @dev: parent device for the exported dmabuf
 231 * @exp_info: the export information used by dma_buf_export()
 232 *
 233 * This wraps dma_buf_export() for use by generic GEM drivers that are using
 234 * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
 235 * a reference to the &drm_device and the exported &drm_gem_object (stored in
 236 * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release().
 237 *
 238 * Returns the new dmabuf.
 239 */
 240struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
 241				      struct dma_buf_export_info *exp_info)
 242{
 243	struct drm_gem_object *obj = exp_info->priv;
 244	struct dma_buf *dma_buf;
 245
 246	dma_buf = dma_buf_export(exp_info);
 247	if (IS_ERR(dma_buf))
 248		return dma_buf;
 
 
 
 249
 250	drm_dev_get(dev);
 251	drm_gem_object_get(obj);
 252	dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
 253
 254	return dma_buf;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 255}
 256EXPORT_SYMBOL(drm_gem_dmabuf_export);
 257
 258/**
 259 * drm_gem_dmabuf_release - &dma_buf release implementation for GEM
 260 * @dma_buf: buffer to be released
 261 *
 262 * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
 263 * must use this in their &dma_buf_ops structure as the release callback.
 264 * drm_gem_dmabuf_release() should be used in conjunction with
 265 * drm_gem_dmabuf_export().
 266 */
 267void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
 268{
 269	struct drm_gem_object *obj = dma_buf->priv;
 270	struct drm_device *dev = obj->dev;
 271
 272	/* drop the reference on the export fd holds */
 273	drm_gem_object_put(obj);
 274
 275	drm_dev_put(dev);
 276}
 277EXPORT_SYMBOL(drm_gem_dmabuf_release);
 278
 279/**
 280 * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
 281 * @dev: dev to export the buffer from
 282 * @file_priv: drm file-private structure
 283 * @prime_fd: fd id of the dma-buf which should be imported
 284 * @handle: pointer to storage for the handle of the imported buffer object
 285 *
 286 * This is the PRIME import function which must be used mandatorily by GEM
 287 * drivers to ensure correct lifetime management of the underlying GEM object.
 288 * The actual importing of GEM object from the dma-buf is done through the
 289 * &drm_driver.gem_prime_import driver callback.
 290 *
 291 * Returns 0 on success or a negative error code on failure.
 292 */
 293int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 294			       struct drm_file *file_priv, int prime_fd,
 295			       uint32_t *handle)
 296{
 297	struct dma_buf *dma_buf;
 298	struct drm_gem_object *obj;
 299	int ret;
 300
 301	dma_buf = dma_buf_get(prime_fd);
 302	if (IS_ERR(dma_buf))
 303		return PTR_ERR(dma_buf);
 304
 305	mutex_lock(&file_priv->prime.lock);
 
 
 
 306
 307	ret = drm_prime_lookup_buf_handle(&file_priv->prime,
 308			dma_buf, handle);
 309	if (ret == 0)
 310		goto out_put;
 311
 312	/* never seen this one, need to import */
 313	mutex_lock(&dev->object_name_lock);
 314	if (dev->driver->gem_prime_import)
 315		obj = dev->driver->gem_prime_import(dev, dma_buf);
 316	else
 317		obj = drm_gem_prime_import(dev, dma_buf);
 318	if (IS_ERR(obj)) {
 319		ret = PTR_ERR(obj);
 320		goto out_unlock;
 321	}
 322
 323	if (obj->dma_buf) {
 324		WARN_ON(obj->dma_buf != dma_buf);
 325	} else {
 326		obj->dma_buf = dma_buf;
 327		get_dma_buf(dma_buf);
 328	}
 329
 330	/* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
 331	ret = drm_gem_handle_create_tail(file_priv, obj, handle);
 332	drm_gem_object_put(obj);
 333	if (ret)
 334		goto out_put;
 
 335
 336	ret = drm_prime_add_buf_handle(&file_priv->prime,
 337			dma_buf, *handle);
 338	mutex_unlock(&file_priv->prime.lock);
 339	if (ret)
 340		goto fail;
 341
 342	dma_buf_put(dma_buf);
 343
 344	return 0;
 
 
 
 
 345
 346fail:
 347	/* hmm, if driver attached, we are relying on the free-object path
 348	 * to detach.. which seems ok..
 349	 */
 350	drm_gem_handle_delete(file_priv, *handle);
 351	dma_buf_put(dma_buf);
 352	return ret;
 353
 354out_unlock:
 355	mutex_unlock(&dev->object_name_lock);
 356out_put:
 357	mutex_unlock(&file_priv->prime.lock);
 358	dma_buf_put(dma_buf);
 359	return ret;
 360}
 361EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
 362
 363int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
 364				 struct drm_file *file_priv)
 365{
 366	struct drm_prime_handle *args = data;
 
 
 
 
 
 
 
 
 
 
 367
 368	if (!dev->driver->prime_fd_to_handle)
 369		return -ENOSYS;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 370
 371	return dev->driver->prime_fd_to_handle(dev, file_priv,
 372			args->fd, &args->handle);
 
 
 
 
 
 
 
 
 
 
 
 373}
 
 374
 375static struct dma_buf *export_and_register_object(struct drm_device *dev,
 376						  struct drm_gem_object *obj,
 377						  uint32_t flags)
 378{
 379	struct dma_buf *dmabuf;
 380
 381	/* prevent races with concurrent gem_close. */
 382	if (obj->handle_count == 0) {
 383		dmabuf = ERR_PTR(-ENOENT);
 384		return dmabuf;
 385	}
 386
 387	if (obj->funcs && obj->funcs->export)
 388		dmabuf = obj->funcs->export(obj, flags);
 389	else
 390		dmabuf = drm_gem_prime_export(obj, flags);
 391	if (IS_ERR(dmabuf)) {
 392		/* normally the created dma-buf takes ownership of the ref,
 393		 * but if that fails then drop the ref
 394		 */
 395		return dmabuf;
 396	}
 397
 398	/*
 399	 * Note that callers do not need to clean up the export cache
 400	 * since the check for obj->handle_count guarantees that someone
 401	 * will clean it up.
 402	 */
 403	obj->dma_buf = dmabuf;
 404	get_dma_buf(obj->dma_buf);
 
 
 405
 406	return dmabuf;
 407}
 408
 409/**
 410 * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
 411 * @dev: dev to export the buffer from
 412 * @file_priv: drm file-private structure
 413 * @handle: buffer handle to export
 414 * @flags: flags like DRM_CLOEXEC
 415 * @prime_fd: pointer to storage for the fd id of the create dma-buf
 416 *
 417 * This is the PRIME export function which must be used mandatorily by GEM
 418 * drivers to ensure correct lifetime management of the underlying GEM object.
 419 * The actual exporting from GEM object to a dma-buf is done through the
 420 * &drm_gem_object_funcs.export callback.
 421 */
 422int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 423			       struct drm_file *file_priv, uint32_t handle,
 424			       uint32_t flags,
 425			       int *prime_fd)
 426{
 427	struct drm_gem_object *obj;
 428	int ret = 0;
 429	struct dma_buf *dmabuf;
 430
 431	mutex_lock(&file_priv->prime.lock);
 432	obj = drm_gem_object_lookup(file_priv, handle);
 433	if (!obj)  {
 434		ret = -ENOENT;
 435		goto out_unlock;
 436	}
 437
 438	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
 439	if (dmabuf) {
 440		get_dma_buf(dmabuf);
 441		goto out_have_handle;
 442	}
 443
 444	mutex_lock(&dev->object_name_lock);
 445	/* re-export the original imported object */
 446	if (obj->import_attach) {
 447		dmabuf = obj->import_attach->dmabuf;
 448		get_dma_buf(dmabuf);
 449		goto out_have_obj;
 450	}
 451
 452	if (obj->dma_buf) {
 453		get_dma_buf(obj->dma_buf);
 454		dmabuf = obj->dma_buf;
 455		goto out_have_obj;
 456	}
 457
 458	dmabuf = export_and_register_object(dev, obj, flags);
 459	if (IS_ERR(dmabuf)) {
 460		/* normally the created dma-buf takes ownership of the ref,
 461		 * but if that fails then drop the ref
 462		 */
 463		ret = PTR_ERR(dmabuf);
 464		mutex_unlock(&dev->object_name_lock);
 465		goto out;
 466	}
 467
 468out_have_obj:
 469	/*
 470	 * If we've exported this buffer then cheat and add it to the import list
 471	 * so we get the correct handle back. We must do this under the
 472	 * protection of dev->object_name_lock to ensure that a racing gem close
 473	 * ioctl doesn't miss to remove this buffer handle from the cache.
 474	 */
 475	ret = drm_prime_add_buf_handle(&file_priv->prime,
 476				       dmabuf, handle);
 477	mutex_unlock(&dev->object_name_lock);
 478	if (ret)
 479		goto fail_put_dmabuf;
 480
 481out_have_handle:
 482	ret = dma_buf_fd(dmabuf, flags);
 483	/*
 484	 * We must _not_ remove the buffer from the handle cache since the newly
 485	 * created dma buf is already linked in the global obj->dma_buf pointer,
 486	 * and that is invariant as long as a userspace gem handle exists.
 487	 * Closing the handle will clean out the cache anyway, so we don't leak.
 488	 */
 489	if (ret < 0) {
 490		goto fail_put_dmabuf;
 491	} else {
 492		*prime_fd = ret;
 493		ret = 0;
 494	}
 495
 496	goto out;
 497
 498fail_put_dmabuf:
 499	dma_buf_put(dmabuf);
 500out:
 501	drm_gem_object_put(obj);
 502out_unlock:
 503	mutex_unlock(&file_priv->prime.lock);
 504
 505	return ret;
 506}
 507EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
 508
 509int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
 510				 struct drm_file *file_priv)
 511{
 512	struct drm_prime_handle *args = data;
 513
 514	if (!dev->driver->prime_handle_to_fd)
 515		return -ENOSYS;
 516
 517	/* check flags are valid */
 518	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
 519		return -EINVAL;
 520
 521	return dev->driver->prime_handle_to_fd(dev, file_priv,
 522			args->handle, args->flags, &args->fd);
 523}
 524
 525/**
 526 * DOC: PRIME Helpers
 527 *
 528 * Drivers can implement &drm_gem_object_funcs.export and
 529 * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper
 530 * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions
 531 * implement dma-buf support in terms of some lower-level helpers, which are
 532 * again exported for drivers to use individually:
 533 *
 534 * Exporting buffers
 535 * ~~~~~~~~~~~~~~~~~
 536 *
 537 * Optional pinning of buffers is handled at dma-buf attach and detach time in
 538 * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
 539 * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
 540 * &drm_gem_object_funcs.get_sg_table.
 541 *
 542 * For kernel-internal access there's drm_gem_dmabuf_vmap() and
 543 * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
 544 * drm_gem_dmabuf_mmap().
 545 *
 546 * Note that these export helpers can only be used if the underlying backing
 547 * storage is fully coherent and either permanently pinned, or it is safe to pin
 548 * it indefinitely.
 549 *
 550 * FIXME: The underlying helper functions are named rather inconsistently.
 551 *
 552 * Exporting buffers
 553 * ~~~~~~~~~~~~~~~~~
 554 *
 555 * Importing dma-bufs using drm_gem_prime_import() relies on
 556 * &drm_driver.gem_prime_import_sg_table.
 557 *
 558 * Note that similarly to the export helpers this permanently pins the
 559 * underlying backing storage. Which is ok for scanout, but is not the best
 560 * option for sharing lots of buffers for rendering.
 561 */
 562
 563/**
 564 * drm_gem_map_attach - dma_buf attach implementation for GEM
 565 * @dma_buf: buffer to attach device to
 566 * @attach: buffer attachment data
 567 *
 568 * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
 569 * used as the &dma_buf_ops.attach callback. Must be used together with
 570 * drm_gem_map_detach().
 571 *
 572 * Returns 0 on success, negative error code on failure.
 573 */
 574int drm_gem_map_attach(struct dma_buf *dma_buf,
 575		       struct dma_buf_attachment *attach)
 576{
 577	struct drm_gem_object *obj = dma_buf->priv;
 578
 579	return drm_gem_pin(obj);
 580}
 581EXPORT_SYMBOL(drm_gem_map_attach);
 582
 583/**
 584 * drm_gem_map_detach - dma_buf detach implementation for GEM
 585 * @dma_buf: buffer to detach from
 586 * @attach: attachment to be detached
 587 *
 588 * Calls &drm_gem_object_funcs.pin for device specific handling.  Cleans up
 589 * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
 590 * &dma_buf_ops.detach callback.
 591 */
 592void drm_gem_map_detach(struct dma_buf *dma_buf,
 593			struct dma_buf_attachment *attach)
 594{
 595	struct drm_gem_object *obj = dma_buf->priv;
 596
 597	drm_gem_unpin(obj);
 598}
 599EXPORT_SYMBOL(drm_gem_map_detach);
 600
 601/**
 602 * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
 603 * @attach: attachment whose scatterlist is to be returned
 604 * @dir: direction of DMA transfer
 605 *
 606 * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
 607 * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
 608 * with drm_gem_unmap_dma_buf().
 609 *
 610 * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
 611 * on error. May return -EINTR if it is interrupted by a signal.
 612 */
 613struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
 614				     enum dma_data_direction dir)
 615{
 616	struct drm_gem_object *obj = attach->dmabuf->priv;
 617	struct sg_table *sgt;
 
 618	int ret;
 619
 620	if (WARN_ON(dir == DMA_NONE))
 621		return ERR_PTR(-EINVAL);
 622
 623	if (WARN_ON(!obj->funcs->get_sg_table))
 624		return ERR_PTR(-ENOSYS);
 625
 626	sgt = obj->funcs->get_sg_table(obj);
 627	if (IS_ERR(sgt))
 628		return sgt;
 629
 630	ret = dma_map_sgtable(attach->dev, sgt, dir,
 631			      DMA_ATTR_SKIP_CPU_SYNC);
 632	if (ret) {
 633		sg_free_table(sgt);
 634		kfree(sgt);
 635		sgt = ERR_PTR(ret);
 636	}
 637
 638	return sgt;
 639}
 640EXPORT_SYMBOL(drm_gem_map_dma_buf);
 641
 642/**
 643 * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
 644 * @attach: attachment to unmap buffer from
 645 * @sgt: scatterlist info of the buffer to unmap
 646 * @dir: direction of DMA transfer
 647 *
 648 * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
 649 */
 650void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 651			   struct sg_table *sgt,
 652			   enum dma_data_direction dir)
 653{
 654	if (!sgt)
 655		return;
 656
 657	dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
 658	sg_free_table(sgt);
 659	kfree(sgt);
 660}
 661EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
 662
 663/**
 664 * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
 665 * @dma_buf: buffer to be mapped
 666 * @map: the virtual address of the buffer
 667 *
 668 * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
 669 * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
 670 * The kernel virtual address is returned in map.
 671 *
 672 * Returns 0 on success or a negative errno code otherwise.
 673 */
 674int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct dma_buf_map *map)
 675{
 676	struct drm_gem_object *obj = dma_buf->priv;
 677
 678	return drm_gem_vmap(obj, map);
 679}
 680EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
 681
 682/**
 683 * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
 684 * @dma_buf: buffer to be unmapped
 685 * @map: the virtual address of the buffer
 686 *
 687 * Releases a kernel virtual mapping. This can be used as the
 688 * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
 689 */
 690void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct dma_buf_map *map)
 691{
 692	struct drm_gem_object *obj = dma_buf->priv;
 693
 694	drm_gem_vunmap(obj, map);
 
 
 
 
 
 
 695}
 696EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
 697
 698/**
 699 * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
 700 * @obj: GEM object
 701 * @vma: Virtual address range
 702 *
 703 * This function sets up a userspace mapping for PRIME exported buffers using
 704 * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
 705 * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
 706 * called to set up the mapping.
 707 *
 708 * Drivers can use this as their &drm_driver.gem_prime_mmap callback.
 
 
 
 709 */
 710int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 
 
 711{
 712	struct drm_file *priv;
 713	struct file *fil;
 714	int ret;
 715
 716	/* Add the fake offset */
 717	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
 
 
 
 718
 719	if (obj->funcs && obj->funcs->mmap) {
 720		vma->vm_ops = obj->funcs->vm_ops;
 
 
 721
 722		ret = obj->funcs->mmap(obj, vma);
 723		if (ret)
 724			return ret;
 725		vma->vm_private_data = obj;
 726		drm_gem_object_get(obj);
 727		return 0;
 728	}
 729
 730	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 731	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
 732	if (!priv || !fil) {
 733		ret = -ENOMEM;
 734		goto out;
 735	}
 736
 737	/* Used by drm_gem_mmap() to lookup the GEM object */
 738	priv->minor = obj->dev->primary;
 739	fil->private_data = priv;
 
 
 740
 741	ret = drm_vma_node_allow(&obj->vma_node, priv);
 
 742	if (ret)
 743		goto out;
 744
 745	ret = obj->dev->driver->fops->mmap(fil, vma);
 746
 747	drm_vma_node_revoke(&obj->vma_node, priv);
 748out:
 749	kfree(priv);
 750	kfree(fil);
 751
 
 
 
 
 
 
 
 
 
 
 752	return ret;
 753}
 754EXPORT_SYMBOL(drm_gem_prime_mmap);
 755
 756/**
 757 * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
 758 * @dma_buf: buffer to be mapped
 759 * @vma: virtual address range
 760 *
 761 * Provides memory mapping for the buffer. This can be used as the
 762 * &dma_buf_ops.mmap callback. It just forwards to &drm_driver.gem_prime_mmap,
 763 * which should be set to drm_gem_prime_mmap().
 764 *
 765 * FIXME: There's really no point to this wrapper, drivers which need anything
 766 * else but drm_gem_prime_mmap can roll their own &dma_buf_ops.mmap callback.
 767 *
 768 * Returns 0 on success or a negative error code on failure.
 769 */
 770int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
 771{
 772	struct drm_gem_object *obj = dma_buf->priv;
 773	struct drm_device *dev = obj->dev;
 774
 775	if (!dev->driver->gem_prime_mmap)
 776		return -ENOSYS;
 777
 778	return dev->driver->gem_prime_mmap(obj, vma);
 779}
 780EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
 781
 782static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
 783	.cache_sgt_mapping = true,
 784	.attach = drm_gem_map_attach,
 785	.detach = drm_gem_map_detach,
 786	.map_dma_buf = drm_gem_map_dma_buf,
 787	.unmap_dma_buf = drm_gem_unmap_dma_buf,
 788	.release = drm_gem_dmabuf_release,
 789	.mmap = drm_gem_dmabuf_mmap,
 790	.vmap = drm_gem_dmabuf_vmap,
 791	.vunmap = drm_gem_dmabuf_vunmap,
 792};
 793
 794/**
 795 * drm_prime_pages_to_sg - converts a page array into an sg list
 796 * @dev: DRM device
 797 * @pages: pointer to the array of page pointers to convert
 798 * @nr_pages: length of the page vector
 799 *
 800 * This helper creates an sg table object from a set of pages
 801 * the driver is responsible for mapping the pages into the
 802 * importers address space for use with dma_buf itself.
 803 *
 804 * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
 805 */
 806struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
 807				       struct page **pages, unsigned int nr_pages)
 808{
 809	struct sg_table *sg;
 810	struct scatterlist *sge;
 811	size_t max_segment = 0;
 812
 813	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
 814	if (!sg)
 815		return ERR_PTR(-ENOMEM);
 816
 817	if (dev)
 818		max_segment = dma_max_mapping_size(dev->dev);
 819	if (max_segment == 0)
 820		max_segment = UINT_MAX;
 821	sge = __sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
 822					  nr_pages << PAGE_SHIFT,
 823					  max_segment,
 824					  NULL, 0, GFP_KERNEL);
 825	if (IS_ERR(sge)) {
 826		kfree(sg);
 827		sg = ERR_CAST(sge);
 828	}
 829	return sg;
 830}
 831EXPORT_SYMBOL(drm_prime_pages_to_sg);
 832
 833/**
 834 * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
 835 * @sgt: sg_table describing the buffer to check
 836 *
 837 * This helper calculates the contiguous size in the DMA address space
 838 * of the the buffer described by the provided sg_table.
 839 *
 840 * This is useful for implementing
 841 * &drm_gem_object_funcs.gem_prime_import_sg_table.
 842 */
 843unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
 844{
 845	dma_addr_t expected = sg_dma_address(sgt->sgl);
 846	struct scatterlist *sg;
 847	unsigned long size = 0;
 848	int i;
 849
 850	for_each_sgtable_dma_sg(sgt, sg, i) {
 851		unsigned int len = sg_dma_len(sg);
 852
 853		if (!len)
 854			break;
 855		if (sg_dma_address(sg) != expected)
 856			break;
 857		expected += len;
 858		size += len;
 859	}
 860	return size;
 861}
 862EXPORT_SYMBOL(drm_prime_get_contiguous_size);
 863
 864/**
 865 * drm_gem_prime_export - helper library implementation of the export callback
 866 * @obj: GEM object to export
 867 * @flags: flags like DRM_CLOEXEC and DRM_RDWR
 868 *
 869 * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
 870 * using the PRIME helpers. It is used as the default in
 871 * drm_gem_prime_handle_to_fd().
 872 */
 873struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
 874				     int flags)
 875{
 876	struct drm_device *dev = obj->dev;
 877	struct dma_buf_export_info exp_info = {
 878		.exp_name = KBUILD_MODNAME, /* white lie for debug */
 879		.owner = dev->driver->fops->owner,
 880		.ops = &drm_gem_prime_dmabuf_ops,
 881		.size = obj->size,
 882		.flags = flags,
 883		.priv = obj,
 884		.resv = obj->resv,
 885	};
 886
 887	return drm_gem_dmabuf_export(dev, &exp_info);
 
 888}
 889EXPORT_SYMBOL(drm_gem_prime_export);
 890
 891/**
 892 * drm_gem_prime_import_dev - core implementation of the import callback
 893 * @dev: drm_device to import into
 894 * @dma_buf: dma-buf object to import
 895 * @attach_dev: struct device to dma_buf attach
 896 *
 897 * This is the core of drm_gem_prime_import(). It's designed to be called by
 898 * drivers who want to use a different device structure than &drm_device.dev for
 899 * attaching via dma_buf. This function calls
 900 * &drm_driver.gem_prime_import_sg_table internally.
 901 *
 902 * Drivers must arrange to call drm_prime_gem_destroy() from their
 903 * &drm_gem_object_funcs.free hook when using this function.
 
 904 */
 905struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
 906					    struct dma_buf *dma_buf,
 907					    struct device *attach_dev)
 908{
 909	struct dma_buf_attachment *attach;
 910	struct sg_table *sgt;
 911	struct drm_gem_object *obj;
 912	int ret;
 913
 914	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
 915		obj = dma_buf->priv;
 916		if (obj->dev == dev) {
 917			/*
 918			 * Importing dmabuf exported from out own gem increases
 919			 * refcount on gem itself instead of f_count of dmabuf.
 920			 */
 921			drm_gem_object_get(obj);
 922			return obj;
 923		}
 924	}
 925
 926	if (!dev->driver->gem_prime_import_sg_table)
 927		return ERR_PTR(-EINVAL);
 928
 929	attach = dma_buf_attach(dma_buf, attach_dev);
 930	if (IS_ERR(attach))
 931		return ERR_CAST(attach);
 932
 933	get_dma_buf(dma_buf);
 934
 935	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
 936	if (IS_ERR(sgt)) {
 937		ret = PTR_ERR(sgt);
 938		goto fail_detach;
 939	}
 940
 941	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
 942	if (IS_ERR(obj)) {
 943		ret = PTR_ERR(obj);
 944		goto fail_unmap;
 945	}
 946
 947	obj->import_attach = attach;
 948	obj->resv = dma_buf->resv;
 949
 950	return obj;
 951
 952fail_unmap:
 953	dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 954fail_detach:
 955	dma_buf_detach(dma_buf, attach);
 956	dma_buf_put(dma_buf);
 957
 
 
 
 958	return ERR_PTR(ret);
 959}
 960EXPORT_SYMBOL(drm_gem_prime_import_dev);
 961
 962/**
 963 * drm_gem_prime_import - helper library implementation of the import callback
 964 * @dev: drm_device to import into
 965 * @dma_buf: dma-buf object to import
 966 *
 967 * This is the implementation of the gem_prime_import functions for GEM drivers
 968 * using the PRIME helpers. Drivers can use this as their
 969 * &drm_driver.gem_prime_import implementation. It is used as the default
 970 * implementation in drm_gem_prime_fd_to_handle().
 971 *
 972 * Drivers must arrange to call drm_prime_gem_destroy() from their
 973 * &drm_gem_object_funcs.free hook when using this function.
 974 */
 975struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 976					    struct dma_buf *dma_buf)
 977{
 978	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
 979}
 980EXPORT_SYMBOL(drm_gem_prime_import);
 981
 982/**
 983 * drm_prime_sg_to_page_array - convert an sg table into a page array
 984 * @sgt: scatter-gather table to convert
 985 * @pages: array of page pointers to store the pages in
 986 * @max_entries: size of the passed-in array
 987 *
 988 * Exports an sg table into an array of pages.
 989 *
 990 * This function is deprecated and strongly discouraged to be used.
 991 * The page array is only useful for page faults and those can corrupt fields
 992 * in the struct page if they are not handled by the exporting driver.
 993 */
 994int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
 995					    struct page **pages,
 996					    int max_entries)
 997{
 998	struct sg_page_iter page_iter;
 999	struct page **p = pages;
1000
1001	for_each_sgtable_page(sgt, &page_iter, 0) {
1002		if (WARN_ON(p - pages >= max_entries))
1003			return -1;
1004		*p++ = sg_page_iter_page(&page_iter);
1005	}
1006	return 0;
1007}
1008EXPORT_SYMBOL(drm_prime_sg_to_page_array);
1009
1010/**
1011 * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
1012 * @sgt: scatter-gather table to convert
1013 * @addrs: array to store the dma bus address of each page
1014 * @max_entries: size of both the passed-in arrays
1015 *
1016 * Exports an sg table into an array of addresses.
1017 *
1018 * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
1019 * implementation.
1020 */
1021int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
1022				   int max_entries)
1023{
1024	struct sg_dma_page_iter dma_iter;
1025	dma_addr_t *a = addrs;
1026
1027	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
1028		if (WARN_ON(a - addrs >= max_entries))
1029			return -1;
1030		*a++ = sg_page_iter_dma_address(&dma_iter);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1031	}
1032	return 0;
1033}
1034EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
1035
1036/**
1037 * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1038 * @obj: GEM object which was created from a dma-buf
1039 * @sg: the sg-table which was pinned at import time
1040 *
1041 * This is the cleanup functions which GEM drivers need to call when they use
1042 * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1043 */
1044void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1045{
1046	struct dma_buf_attachment *attach;
1047	struct dma_buf *dma_buf;
1048
1049	attach = obj->import_attach;
1050	if (sg)
1051		dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
1052	dma_buf = attach->dmabuf;
1053	dma_buf_detach(attach->dmabuf, attach);
1054	/* remove the reference */
1055	dma_buf_put(dma_buf);
1056}
1057EXPORT_SYMBOL(drm_prime_gem_destroy);