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 if (dev->driver->gem_prime_export)
 390		dmabuf = dev->driver->gem_prime_export(obj, flags);
 391	else
 392		dmabuf = drm_gem_prime_export(obj, flags);
 393	if (IS_ERR(dmabuf)) {
 394		/* normally the created dma-buf takes ownership of the ref,
 395		 * but if that fails then drop the ref
 396		 */
 397		return dmabuf;
 398	}
 399
 400	/*
 401	 * Note that callers do not need to clean up the export cache
 402	 * since the check for obj->handle_count guarantees that someone
 403	 * will clean it up.
 404	 */
 405	obj->dma_buf = dmabuf;
 406	get_dma_buf(obj->dma_buf);
 
 
 407
 408	return dmabuf;
 409}
 410
 411/**
 412 * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
 413 * @dev: dev to export the buffer from
 414 * @file_priv: drm file-private structure
 415 * @handle: buffer handle to export
 416 * @flags: flags like DRM_CLOEXEC
 417 * @prime_fd: pointer to storage for the fd id of the create dma-buf
 418 *
 419 * This is the PRIME export function which must be used mandatorily by GEM
 420 * drivers to ensure correct lifetime management of the underlying GEM object.
 421 * The actual exporting from GEM object to a dma-buf is done through the
 422 * &drm_driver.gem_prime_export driver callback.
 423 */
 424int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 425			       struct drm_file *file_priv, uint32_t handle,
 426			       uint32_t flags,
 427			       int *prime_fd)
 428{
 429	struct drm_gem_object *obj;
 430	int ret = 0;
 431	struct dma_buf *dmabuf;
 432
 433	mutex_lock(&file_priv->prime.lock);
 434	obj = drm_gem_object_lookup(file_priv, handle);
 435	if (!obj)  {
 436		ret = -ENOENT;
 437		goto out_unlock;
 438	}
 439
 440	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
 441	if (dmabuf) {
 442		get_dma_buf(dmabuf);
 443		goto out_have_handle;
 444	}
 445
 446	mutex_lock(&dev->object_name_lock);
 447	/* re-export the original imported object */
 448	if (obj->import_attach) {
 449		dmabuf = obj->import_attach->dmabuf;
 450		get_dma_buf(dmabuf);
 451		goto out_have_obj;
 452	}
 453
 454	if (obj->dma_buf) {
 455		get_dma_buf(obj->dma_buf);
 456		dmabuf = obj->dma_buf;
 457		goto out_have_obj;
 458	}
 459
 460	dmabuf = export_and_register_object(dev, obj, flags);
 461	if (IS_ERR(dmabuf)) {
 462		/* normally the created dma-buf takes ownership of the ref,
 463		 * but if that fails then drop the ref
 464		 */
 465		ret = PTR_ERR(dmabuf);
 466		mutex_unlock(&dev->object_name_lock);
 467		goto out;
 468	}
 469
 470out_have_obj:
 471	/*
 472	 * If we've exported this buffer then cheat and add it to the import list
 473	 * so we get the correct handle back. We must do this under the
 474	 * protection of dev->object_name_lock to ensure that a racing gem close
 475	 * ioctl doesn't miss to remove this buffer handle from the cache.
 476	 */
 477	ret = drm_prime_add_buf_handle(&file_priv->prime,
 478				       dmabuf, handle);
 479	mutex_unlock(&dev->object_name_lock);
 480	if (ret)
 481		goto fail_put_dmabuf;
 482
 483out_have_handle:
 484	ret = dma_buf_fd(dmabuf, flags);
 485	/*
 486	 * We must _not_ remove the buffer from the handle cache since the newly
 487	 * created dma buf is already linked in the global obj->dma_buf pointer,
 488	 * and that is invariant as long as a userspace gem handle exists.
 489	 * Closing the handle will clean out the cache anyway, so we don't leak.
 490	 */
 491	if (ret < 0) {
 492		goto fail_put_dmabuf;
 493	} else {
 494		*prime_fd = ret;
 495		ret = 0;
 496	}
 497
 498	goto out;
 499
 500fail_put_dmabuf:
 501	dma_buf_put(dmabuf);
 502out:
 503	drm_gem_object_put(obj);
 504out_unlock:
 505	mutex_unlock(&file_priv->prime.lock);
 506
 507	return ret;
 508}
 509EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
 510
 511int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
 512				 struct drm_file *file_priv)
 513{
 514	struct drm_prime_handle *args = data;
 515
 516	if (!dev->driver->prime_handle_to_fd)
 517		return -ENOSYS;
 518
 519	/* check flags are valid */
 520	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
 521		return -EINVAL;
 522
 523	return dev->driver->prime_handle_to_fd(dev, file_priv,
 524			args->handle, args->flags, &args->fd);
 525}
 526
 527/**
 528 * DOC: PRIME Helpers
 529 *
 530 * Drivers can implement &drm_gem_object_funcs.export and
 531 * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper
 532 * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions
 533 * implement dma-buf support in terms of some lower-level helpers, which are
 534 * again exported for drivers to use individually:
 535 *
 536 * Exporting buffers
 537 * ~~~~~~~~~~~~~~~~~
 538 *
 539 * Optional pinning of buffers is handled at dma-buf attach and detach time in
 540 * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
 541 * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
 542 * &drm_gem_object_funcs.get_sg_table.
 543 *
 544 * For kernel-internal access there's drm_gem_dmabuf_vmap() and
 545 * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
 546 * drm_gem_dmabuf_mmap().
 547 *
 548 * Note that these export helpers can only be used if the underlying backing
 549 * storage is fully coherent and either permanently pinned, or it is safe to pin
 550 * it indefinitely.
 551 *
 552 * FIXME: The underlying helper functions are named rather inconsistently.
 553 *
 554 * Exporting buffers
 555 * ~~~~~~~~~~~~~~~~~
 556 *
 557 * Importing dma-bufs using drm_gem_prime_import() relies on
 558 * &drm_driver.gem_prime_import_sg_table.
 559 *
 560 * Note that similarly to the export helpers this permanently pins the
 561 * underlying backing storage. Which is ok for scanout, but is not the best
 562 * option for sharing lots of buffers for rendering.
 563 */
 564
 565/**
 566 * drm_gem_map_attach - dma_buf attach implementation for GEM
 567 * @dma_buf: buffer to attach device to
 568 * @attach: buffer attachment data
 569 *
 570 * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
 571 * used as the &dma_buf_ops.attach callback. Must be used together with
 572 * drm_gem_map_detach().
 573 *
 574 * Returns 0 on success, negative error code on failure.
 575 */
 576int drm_gem_map_attach(struct dma_buf *dma_buf,
 577		       struct dma_buf_attachment *attach)
 578{
 579	struct drm_gem_object *obj = dma_buf->priv;
 580
 581	return drm_gem_pin(obj);
 582}
 583EXPORT_SYMBOL(drm_gem_map_attach);
 584
 585/**
 586 * drm_gem_map_detach - dma_buf detach implementation for GEM
 587 * @dma_buf: buffer to detach from
 588 * @attach: attachment to be detached
 589 *
 590 * Calls &drm_gem_object_funcs.pin for device specific handling.  Cleans up
 591 * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
 592 * &dma_buf_ops.detach callback.
 593 */
 594void drm_gem_map_detach(struct dma_buf *dma_buf,
 595			struct dma_buf_attachment *attach)
 596{
 597	struct drm_gem_object *obj = dma_buf->priv;
 598
 599	drm_gem_unpin(obj);
 600}
 601EXPORT_SYMBOL(drm_gem_map_detach);
 602
 603/**
 604 * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
 605 * @attach: attachment whose scatterlist is to be returned
 606 * @dir: direction of DMA transfer
 607 *
 608 * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
 609 * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
 610 * with drm_gem_unmap_dma_buf().
 611 *
 612 * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
 613 * on error. May return -EINTR if it is interrupted by a signal.
 614 */
 615struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
 616				     enum dma_data_direction dir)
 617{
 618	struct drm_gem_object *obj = attach->dmabuf->priv;
 619	struct sg_table *sgt;
 
 
 620
 621	if (WARN_ON(dir == DMA_NONE))
 622		return ERR_PTR(-EINVAL);
 623
 624	if (obj->funcs)
 625		sgt = obj->funcs->get_sg_table(obj);
 626	else
 627		sgt = obj->dev->driver->gem_prime_get_sg_table(obj);
 628
 629	if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
 630			      DMA_ATTR_SKIP_CPU_SYNC)) {
 631		sg_free_table(sgt);
 632		kfree(sgt);
 633		sgt = ERR_PTR(-ENOMEM);
 634	}
 635
 636	return sgt;
 637}
 638EXPORT_SYMBOL(drm_gem_map_dma_buf);
 639
 640/**
 641 * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
 642 * @attach: attachment to unmap buffer from
 643 * @sgt: scatterlist info of the buffer to unmap
 644 * @dir: direction of DMA transfer
 645 *
 646 * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
 647 */
 648void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 649			   struct sg_table *sgt,
 650			   enum dma_data_direction dir)
 651{
 652	if (!sgt)
 653		return;
 654
 655	dma_unmap_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
 656			   DMA_ATTR_SKIP_CPU_SYNC);
 657	sg_free_table(sgt);
 658	kfree(sgt);
 659}
 660EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
 661
 662/**
 663 * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
 664 * @dma_buf: buffer to be mapped
 665 *
 666 * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
 667 * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
 668 *
 669 * Returns the kernel virtual address or NULL on failure.
 670 */
 671void *drm_gem_dmabuf_vmap(struct dma_buf *dma_buf)
 672{
 673	struct drm_gem_object *obj = dma_buf->priv;
 674	void *vaddr;
 675
 676	vaddr = drm_gem_vmap(obj);
 677	if (IS_ERR(vaddr))
 678		vaddr = NULL;
 679
 680	return vaddr;
 681}
 682EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
 683
 684/**
 685 * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
 686 * @dma_buf: buffer to be unmapped
 687 * @vaddr: the virtual address of the buffer
 688 *
 689 * Releases a kernel virtual mapping. This can be used as the
 690 * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
 691 */
 692void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, void *vaddr)
 693{
 694	struct drm_gem_object *obj = dma_buf->priv;
 695
 696	drm_gem_vunmap(obj, vaddr);
 697}
 698EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
 699
 700/**
 701 * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
 702 * @obj: GEM object
 703 * @vma: Virtual address range
 704 *
 705 * This function sets up a userspace mapping for PRIME exported buffers using
 706 * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
 707 * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
 708 * called to set up the mapping.
 709 *
 710 * Drivers can use this as their &drm_driver.gem_prime_mmap callback.
 
 
 
 711 */
 712int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 
 
 713{
 714	struct drm_file *priv;
 715	struct file *fil;
 716	int ret;
 717
 718	/* Add the fake offset */
 719	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
 
 720
 721	if (obj->funcs && obj->funcs->mmap) {
 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 * @pages: pointer to the array of page pointers to convert
 797 * @nr_pages: length of the page vector
 798 *
 799 * This helper creates an sg table object from a set of pages
 800 * the driver is responsible for mapping the pages into the
 801 * importers address space for use with dma_buf itself.
 802 *
 803 * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
 804 */
 805struct sg_table *drm_prime_pages_to_sg(struct page **pages, unsigned int nr_pages)
 806{
 807	struct sg_table *sg = NULL;
 808	int ret;
 809
 810	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
 811	if (!sg) {
 812		ret = -ENOMEM;
 813		goto out;
 814	}
 815
 816	ret = sg_alloc_table_from_pages(sg, pages, nr_pages, 0,
 817				nr_pages << PAGE_SHIFT, GFP_KERNEL);
 818	if (ret)
 819		goto out;
 820
 821	return sg;
 822out:
 823	kfree(sg);
 824	return ERR_PTR(ret);
 825}
 826EXPORT_SYMBOL(drm_prime_pages_to_sg);
 827
 828/**
 829 * drm_gem_prime_export - helper library implementation of the export callback
 830 * @obj: GEM object to export
 831 * @flags: flags like DRM_CLOEXEC and DRM_RDWR
 832 *
 833 * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
 834 * using the PRIME helpers. It is used as the default in
 835 * drm_gem_prime_handle_to_fd().
 836 */
 837struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
 838				     int flags)
 839{
 840	struct drm_device *dev = obj->dev;
 841	struct dma_buf_export_info exp_info = {
 842		.exp_name = KBUILD_MODNAME, /* white lie for debug */
 843		.owner = dev->driver->fops->owner,
 844		.ops = &drm_gem_prime_dmabuf_ops,
 845		.size = obj->size,
 846		.flags = flags,
 847		.priv = obj,
 848		.resv = obj->resv,
 849	};
 850
 851	return drm_gem_dmabuf_export(dev, &exp_info);
 852}
 853EXPORT_SYMBOL(drm_gem_prime_export);
 854
 855/**
 856 * drm_gem_prime_import_dev - core implementation of the import callback
 857 * @dev: drm_device to import into
 858 * @dma_buf: dma-buf object to import
 859 * @attach_dev: struct device to dma_buf attach
 860 *
 861 * This is the core of drm_gem_prime_import(). It's designed to be called by
 862 * drivers who want to use a different device structure than &drm_device.dev for
 863 * attaching via dma_buf. This function calls
 864 * &drm_driver.gem_prime_import_sg_table internally.
 865 *
 866 * Drivers must arrange to call drm_prime_gem_destroy() from their
 867 * &drm_gem_object_funcs.free hook when using this function.
 868 */
 869struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
 870					    struct dma_buf *dma_buf,
 871					    struct device *attach_dev)
 872{
 873	struct dma_buf_attachment *attach;
 874	struct sg_table *sgt;
 875	struct drm_gem_object *obj;
 876	int ret;
 877
 878	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
 879		obj = dma_buf->priv;
 880		if (obj->dev == dev) {
 881			/*
 882			 * Importing dmabuf exported from out own gem increases
 883			 * refcount on gem itself instead of f_count of dmabuf.
 884			 */
 885			drm_gem_object_get(obj);
 886			return obj;
 887		}
 888	}
 889
 890	if (!dev->driver->gem_prime_import_sg_table)
 891		return ERR_PTR(-EINVAL);
 892
 893	attach = dma_buf_attach(dma_buf, attach_dev);
 894	if (IS_ERR(attach))
 895		return ERR_CAST(attach);
 896
 897	get_dma_buf(dma_buf);
 898
 899	sgt = dma_buf_map_attachment(attach, DMA_BIDIRECTIONAL);
 900	if (IS_ERR(sgt)) {
 901		ret = PTR_ERR(sgt);
 902		goto fail_detach;
 903	}
 904
 905	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
 906	if (IS_ERR(obj)) {
 907		ret = PTR_ERR(obj);
 908		goto fail_unmap;
 909	}
 910
 911	obj->import_attach = attach;
 912	obj->resv = dma_buf->resv;
 913
 914	return obj;
 915
 916fail_unmap:
 917	dma_buf_unmap_attachment(attach, sgt, DMA_BIDIRECTIONAL);
 918fail_detach:
 919	dma_buf_detach(dma_buf, attach);
 920	dma_buf_put(dma_buf);
 921
 922	return ERR_PTR(ret);
 923}
 924EXPORT_SYMBOL(drm_gem_prime_import_dev);
 925
 926/**
 927 * drm_gem_prime_import - helper library implementation of the import callback
 928 * @dev: drm_device to import into
 929 * @dma_buf: dma-buf object to import
 930 *
 931 * This is the implementation of the gem_prime_import functions for GEM drivers
 932 * using the PRIME helpers. Drivers can use this as their
 933 * &drm_driver.gem_prime_import implementation. It is used as the default
 934 * implementation in drm_gem_prime_fd_to_handle().
 935 *
 936 * Drivers must arrange to call drm_prime_gem_destroy() from their
 937 * &drm_gem_object_funcs.free hook when using this function.
 938 */
 939struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 940					    struct dma_buf *dma_buf)
 941{
 942	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
 943}
 944EXPORT_SYMBOL(drm_gem_prime_import);
 945
 946/**
 947 * drm_prime_sg_to_page_addr_arrays - convert an sg table into a page array
 948 * @sgt: scatter-gather table to convert
 949 * @pages: optional array of page pointers to store the page array in
 950 * @addrs: optional array to store the dma bus address of each page
 951 * @max_entries: size of both the passed-in arrays
 952 *
 953 * Exports an sg table into an array of pages and addresses. This is currently
 954 * required by the TTM driver in order to do correct fault handling.
 955 *
 956 * Drivers can use this in their &drm_driver.gem_prime_import_sg_table
 957 * implementation.
 958 */
 959int drm_prime_sg_to_page_addr_arrays(struct sg_table *sgt, struct page **pages,
 960				     dma_addr_t *addrs, int max_entries)
 961{
 962	unsigned count;
 963	struct scatterlist *sg;
 964	struct page *page;
 965	u32 page_len, page_index;
 
 966	dma_addr_t addr;
 967	u32 dma_len, dma_index;
 968
 969	/*
 970	 * Scatterlist elements contains both pages and DMA addresses, but
 971	 * one shoud not assume 1:1 relation between them. The sg->length is
 972	 * the size of the physical memory chunk described by the sg->page,
 973	 * while sg_dma_len(sg) is the size of the DMA (IO virtual) chunk
 974	 * described by the sg_dma_address(sg).
 975	 */
 976	page_index = 0;
 977	dma_index = 0;
 978	for_each_sg(sgt->sgl, sg, sgt->nents, count) {
 979		page_len = sg->length;
 980		page = sg_page(sg);
 981		dma_len = sg_dma_len(sg);
 982		addr = sg_dma_address(sg);
 983
 984		while (pages && page_len > 0) {
 985			if (WARN_ON(page_index >= max_entries))
 986				return -1;
 987			pages[page_index] = page;
 
 
 
 988			page++;
 989			page_len -= PAGE_SIZE;
 990			page_index++;
 991		}
 992		while (addrs && dma_len > 0) {
 993			if (WARN_ON(dma_index >= max_entries))
 994				return -1;
 995			addrs[dma_index] = addr;
 996			addr += PAGE_SIZE;
 997			dma_len -= PAGE_SIZE;
 998			dma_index++;
 999		}
1000	}
1001	return 0;
1002}
1003EXPORT_SYMBOL(drm_prime_sg_to_page_addr_arrays);
1004
1005/**
1006 * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1007 * @obj: GEM object which was created from a dma-buf
1008 * @sg: the sg-table which was pinned at import time
1009 *
1010 * This is the cleanup functions which GEM drivers need to call when they use
1011 * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1012 */
1013void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1014{
1015	struct dma_buf_attachment *attach;
1016	struct dma_buf *dma_buf;
1017
1018	attach = obj->import_attach;
1019	if (sg)
1020		dma_buf_unmap_attachment(attach, sg, DMA_BIDIRECTIONAL);
1021	dma_buf = attach->dmabuf;
1022	dma_buf_detach(attach->dmabuf, attach);
1023	/* remove the reference */
1024	dma_buf_put(dma_buf);
1025}
1026EXPORT_SYMBOL(drm_prime_gem_destroy);