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#include <linux/module.h>
  33
  34#include <drm/drm.h>
  35#include <drm/drm_drv.h>
  36#include <drm/drm_file.h>
  37#include <drm/drm_framebuffer.h>
  38#include <drm/drm_gem.h>
  39#include <drm/drm_prime.h>
  40
  41#include "drm_internal.h"
  42
  43MODULE_IMPORT_NS(DMA_BUF);
  44
  45/**
  46 * DOC: overview and lifetime rules
  47 *
  48 * Similar to GEM global names, PRIME file descriptors are also used to share
  49 * buffer objects across processes. They offer additional security: as file
  50 * descriptors must be explicitly sent over UNIX domain sockets to be shared
  51 * between applications, they can't be guessed like the globally unique GEM
  52 * names.
  53 *
  54 * Drivers that support the PRIME API implement the
  55 * &drm_driver.prime_handle_to_fd and &drm_driver.prime_fd_to_handle operations.
  56 * GEM based drivers must use drm_gem_prime_handle_to_fd() and
  57 * drm_gem_prime_fd_to_handle() to implement these. For GEM based drivers the
  58 * actual driver interfaces is provided through the &drm_gem_object_funcs.export
  59 * and &drm_driver.gem_prime_import hooks.
  60 *
  61 * &dma_buf_ops implementations for GEM drivers are all individually exported
  62 * for drivers which need to overwrite or reimplement some of them.
  63 *
  64 * Reference Counting for GEM Drivers
  65 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  66 *
  67 * On the export the &dma_buf holds a reference to the exported buffer object,
  68 * usually a &drm_gem_object. It takes this reference in the PRIME_HANDLE_TO_FD
  69 * IOCTL, when it first calls &drm_gem_object_funcs.export
  70 * and stores the exporting GEM object in the &dma_buf.priv field. This
  71 * reference needs to be released when the final reference to the &dma_buf
  72 * itself is dropped and its &dma_buf_ops.release function is called.  For
  73 * GEM-based drivers, the &dma_buf should be exported using
  74 * drm_gem_dmabuf_export() and then released by drm_gem_dmabuf_release().
  75 *
  76 * Thus the chain of references always flows in one direction, avoiding loops:
  77 * importing GEM object -> dma-buf -> exported GEM bo. A further complication
  78 * are the lookup caches for import and export. These are required to guarantee
  79 * that any given object will always have only one unique userspace handle. This
  80 * is required to allow userspace to detect duplicated imports, since some GEM
  81 * drivers do fail command submissions if a given buffer object is listed more
  82 * than once. These import and export caches in &drm_prime_file_private only
  83 * retain a weak reference, which is cleaned up when the corresponding object is
  84 * released.
  85 *
  86 * Self-importing: If userspace is using PRIME as a replacement for flink then
  87 * it will get a fd->handle request for a GEM object that it created.  Drivers
  88 * should detect this situation and return back the underlying object from the
  89 * dma-buf private. For GEM based drivers this is handled in
  90 * drm_gem_prime_import() already.
  91 */
  92
  93struct drm_prime_member {
 
  94	struct dma_buf *dma_buf;
  95	uint32_t handle;
  96
  97	struct rb_node dmabuf_rb;
  98	struct rb_node handle_rb;
  99};
 100
 101static int drm_prime_add_buf_handle(struct drm_prime_file_private *prime_fpriv,
 102				    struct dma_buf *dma_buf, uint32_t handle)
 
 103{
 104	struct drm_prime_member *member;
 105	struct rb_node **p, *rb;
 106
 107	member = kmalloc(sizeof(*member), GFP_KERNEL);
 108	if (!member)
 109		return -ENOMEM;
 110
 111	get_dma_buf(dma_buf);
 112	member->dma_buf = dma_buf;
 113	member->handle = handle;
 114
 115	rb = NULL;
 116	p = &prime_fpriv->dmabufs.rb_node;
 117	while (*p) {
 118		struct drm_prime_member *pos;
 119
 120		rb = *p;
 121		pos = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
 122		if (dma_buf > pos->dma_buf)
 123			p = &rb->rb_right;
 124		else
 125			p = &rb->rb_left;
 126	}
 127	rb_link_node(&member->dmabuf_rb, rb, p);
 128	rb_insert_color(&member->dmabuf_rb, &prime_fpriv->dmabufs);
 129
 130	rb = NULL;
 131	p = &prime_fpriv->handles.rb_node;
 132	while (*p) {
 133		struct drm_prime_member *pos;
 134
 135		rb = *p;
 136		pos = rb_entry(rb, struct drm_prime_member, handle_rb);
 137		if (handle > pos->handle)
 138			p = &rb->rb_right;
 139		else
 140			p = &rb->rb_left;
 141	}
 142	rb_link_node(&member->handle_rb, rb, p);
 143	rb_insert_color(&member->handle_rb, &prime_fpriv->handles);
 144
 145	return 0;
 146}
 147
 148static struct dma_buf *drm_prime_lookup_buf_by_handle(struct drm_prime_file_private *prime_fpriv,
 149						      uint32_t handle)
 150{
 151	struct rb_node *rb;
 152
 153	rb = prime_fpriv->handles.rb_node;
 154	while (rb) {
 155		struct drm_prime_member *member;
 156
 157		member = rb_entry(rb, struct drm_prime_member, handle_rb);
 158		if (member->handle == handle)
 159			return member->dma_buf;
 160		else if (member->handle < handle)
 161			rb = rb->rb_right;
 162		else
 163			rb = rb->rb_left;
 164	}
 165
 166	return NULL;
 167}
 168
 169static int drm_prime_lookup_buf_handle(struct drm_prime_file_private *prime_fpriv,
 170				       struct dma_buf *dma_buf,
 171				       uint32_t *handle)
 172{
 173	struct rb_node *rb;
 174
 175	rb = prime_fpriv->dmabufs.rb_node;
 176	while (rb) {
 177		struct drm_prime_member *member;
 178
 179		member = rb_entry(rb, struct drm_prime_member, dmabuf_rb);
 180		if (member->dma_buf == dma_buf) {
 181			*handle = member->handle;
 182			return 0;
 183		} else if (member->dma_buf < dma_buf) {
 184			rb = rb->rb_right;
 185		} else {
 186			rb = rb->rb_left;
 187		}
 
 
 188	}
 189
 190	return -ENOENT;
 191}
 192
 193void drm_prime_remove_buf_handle(struct drm_prime_file_private *prime_fpriv,
 194				 uint32_t handle)
 195{
 196	struct rb_node *rb;
 197
 198	mutex_lock(&prime_fpriv->lock);
 199
 200	rb = prime_fpriv->handles.rb_node;
 201	while (rb) {
 202		struct drm_prime_member *member;
 203
 204		member = rb_entry(rb, struct drm_prime_member, handle_rb);
 205		if (member->handle == handle) {
 206			rb_erase(&member->handle_rb, &prime_fpriv->handles);
 207			rb_erase(&member->dmabuf_rb, &prime_fpriv->dmabufs);
 208
 209			dma_buf_put(member->dma_buf);
 210			kfree(member);
 211			break;
 212		} else if (member->handle < handle) {
 213			rb = rb->rb_right;
 214		} else {
 215			rb = rb->rb_left;
 216		}
 217	}
 218
 219	mutex_unlock(&prime_fpriv->lock);
 220}
 221
 222void drm_prime_init_file_private(struct drm_prime_file_private *prime_fpriv)
 223{
 224	mutex_init(&prime_fpriv->lock);
 225	prime_fpriv->dmabufs = RB_ROOT;
 226	prime_fpriv->handles = RB_ROOT;
 227}
 228
 229void drm_prime_destroy_file_private(struct drm_prime_file_private *prime_fpriv)
 230{
 231	/* by now drm_gem_release should've made sure the list is empty */
 232	WARN_ON(!RB_EMPTY_ROOT(&prime_fpriv->dmabufs));
 233}
 234
 235/**
 236 * drm_gem_dmabuf_export - &dma_buf export implementation for GEM
 237 * @dev: parent device for the exported dmabuf
 238 * @exp_info: the export information used by dma_buf_export()
 239 *
 240 * This wraps dma_buf_export() for use by generic GEM drivers that are using
 241 * drm_gem_dmabuf_release(). In addition to calling dma_buf_export(), we take
 242 * a reference to the &drm_device and the exported &drm_gem_object (stored in
 243 * &dma_buf_export_info.priv) which is released by drm_gem_dmabuf_release().
 244 *
 245 * Returns the new dmabuf.
 246 */
 247struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
 248				      struct dma_buf_export_info *exp_info)
 249{
 250	struct drm_gem_object *obj = exp_info->priv;
 251	struct dma_buf *dma_buf;
 252
 253	dma_buf = dma_buf_export(exp_info);
 254	if (IS_ERR(dma_buf))
 255		return dma_buf;
 256
 257	drm_dev_get(dev);
 258	drm_gem_object_get(obj);
 259	dma_buf->file->f_mapping = obj->dev->anon_inode->i_mapping;
 260
 261	return dma_buf;
 262}
 263EXPORT_SYMBOL(drm_gem_dmabuf_export);
 264
 265/**
 266 * drm_gem_dmabuf_release - &dma_buf release implementation for GEM
 267 * @dma_buf: buffer to be released
 268 *
 269 * Generic release function for dma_bufs exported as PRIME buffers. GEM drivers
 270 * must use this in their &dma_buf_ops structure as the release callback.
 271 * drm_gem_dmabuf_release() should be used in conjunction with
 272 * drm_gem_dmabuf_export().
 273 */
 274void drm_gem_dmabuf_release(struct dma_buf *dma_buf)
 275{
 276	struct drm_gem_object *obj = dma_buf->priv;
 277	struct drm_device *dev = obj->dev;
 278
 279	/* drop the reference on the export fd holds */
 280	drm_gem_object_put(obj);
 281
 282	drm_dev_put(dev);
 283}
 284EXPORT_SYMBOL(drm_gem_dmabuf_release);
 285
 286/**
 287 * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
 288 * @dev: dev to export the buffer from
 289 * @file_priv: drm file-private structure
 290 * @prime_fd: fd id of the dma-buf which should be imported
 291 * @handle: pointer to storage for the handle of the imported buffer object
 292 *
 293 * This is the PRIME import function which must be used mandatorily by GEM
 294 * drivers to ensure correct lifetime management of the underlying GEM object.
 295 * The actual importing of GEM object from the dma-buf is done through the
 296 * &drm_driver.gem_prime_import driver callback.
 297 *
 298 * Returns 0 on success or a negative error code on failure.
 299 */
 300int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 301			       struct drm_file *file_priv, int prime_fd,
 302			       uint32_t *handle)
 303{
 304	struct dma_buf *dma_buf;
 305	struct drm_gem_object *obj;
 306	int ret;
 307
 308	dma_buf = dma_buf_get(prime_fd);
 309	if (IS_ERR(dma_buf))
 310		return PTR_ERR(dma_buf);
 311
 312	mutex_lock(&file_priv->prime.lock);
 313
 314	ret = drm_prime_lookup_buf_handle(&file_priv->prime,
 315			dma_buf, handle);
 316	if (ret == 0)
 
 317		goto out_put;
 
 318
 319	/* never seen this one, need to import */
 320	mutex_lock(&dev->object_name_lock);
 321	if (dev->driver->gem_prime_import)
 322		obj = dev->driver->gem_prime_import(dev, dma_buf);
 323	else
 324		obj = drm_gem_prime_import(dev, dma_buf);
 325	if (IS_ERR(obj)) {
 326		ret = PTR_ERR(obj);
 327		goto out_unlock;
 328	}
 329
 330	if (obj->dma_buf) {
 331		WARN_ON(obj->dma_buf != dma_buf);
 332	} else {
 333		obj->dma_buf = dma_buf;
 334		get_dma_buf(dma_buf);
 335	}
 336
 337	/* _handle_create_tail unconditionally unlocks dev->object_name_lock. */
 338	ret = drm_gem_handle_create_tail(file_priv, obj, handle);
 339	drm_gem_object_put(obj);
 340	if (ret)
 341		goto out_put;
 342
 343	ret = drm_prime_add_buf_handle(&file_priv->prime,
 344			dma_buf, *handle);
 345	mutex_unlock(&file_priv->prime.lock);
 346	if (ret)
 347		goto fail;
 348
 349	dma_buf_put(dma_buf);
 350
 351	return 0;
 352
 353fail:
 354	/* hmm, if driver attached, we are relying on the free-object path
 355	 * to detach.. which seems ok..
 356	 */
 357	drm_gem_handle_delete(file_priv, *handle);
 358	dma_buf_put(dma_buf);
 359	return ret;
 360
 361out_unlock:
 362	mutex_unlock(&dev->object_name_lock);
 363out_put:
 364	mutex_unlock(&file_priv->prime.lock);
 365	dma_buf_put(dma_buf);
 366	return ret;
 367}
 368EXPORT_SYMBOL(drm_gem_prime_fd_to_handle);
 369
 370int drm_prime_fd_to_handle_ioctl(struct drm_device *dev, void *data,
 371				 struct drm_file *file_priv)
 372{
 373	struct drm_prime_handle *args = data;
 374
 375	if (!dev->driver->prime_fd_to_handle)
 376		return -ENOSYS;
 377
 378	return dev->driver->prime_fd_to_handle(dev, file_priv,
 379			args->fd, &args->handle);
 380}
 381
 382static struct dma_buf *export_and_register_object(struct drm_device *dev,
 383						  struct drm_gem_object *obj,
 384						  uint32_t flags)
 385{
 386	struct dma_buf *dmabuf;
 387
 388	/* prevent races with concurrent gem_close. */
 389	if (obj->handle_count == 0) {
 390		dmabuf = ERR_PTR(-ENOENT);
 391		return dmabuf;
 392	}
 393
 394	if (obj->funcs && obj->funcs->export)
 395		dmabuf = obj->funcs->export(obj, flags);
 396	else
 397		dmabuf = drm_gem_prime_export(obj, flags);
 398	if (IS_ERR(dmabuf)) {
 399		/* normally the created dma-buf takes ownership of the ref,
 400		 * but if that fails then drop the ref
 401		 */
 402		return dmabuf;
 403	}
 404
 405	/*
 406	 * Note that callers do not need to clean up the export cache
 407	 * since the check for obj->handle_count guarantees that someone
 408	 * will clean it up.
 409	 */
 410	obj->dma_buf = dmabuf;
 411	get_dma_buf(obj->dma_buf);
 412
 413	return dmabuf;
 414}
 415
 416/**
 417 * drm_gem_prime_handle_to_fd - PRIME export function for GEM drivers
 418 * @dev: dev to export the buffer from
 419 * @file_priv: drm file-private structure
 420 * @handle: buffer handle to export
 421 * @flags: flags like DRM_CLOEXEC
 422 * @prime_fd: pointer to storage for the fd id of the create dma-buf
 423 *
 424 * This is the PRIME export function which must be used mandatorily by GEM
 425 * drivers to ensure correct lifetime management of the underlying GEM object.
 426 * The actual exporting from GEM object to a dma-buf is done through the
 427 * &drm_gem_object_funcs.export callback.
 428 */
 429int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 430			       struct drm_file *file_priv, uint32_t handle,
 431			       uint32_t flags,
 432			       int *prime_fd)
 433{
 434	struct drm_gem_object *obj;
 435	int ret = 0;
 436	struct dma_buf *dmabuf;
 437
 438	mutex_lock(&file_priv->prime.lock);
 439	obj = drm_gem_object_lookup(file_priv, handle);
 440	if (!obj)  {
 441		ret = -ENOENT;
 442		goto out_unlock;
 443	}
 444
 445	dmabuf = drm_prime_lookup_buf_by_handle(&file_priv->prime, handle);
 446	if (dmabuf) {
 447		get_dma_buf(dmabuf);
 448		goto out_have_handle;
 449	}
 450
 451	mutex_lock(&dev->object_name_lock);
 452	/* re-export the original imported object */
 453	if (obj->import_attach) {
 454		dmabuf = obj->import_attach->dmabuf;
 455		get_dma_buf(dmabuf);
 456		goto out_have_obj;
 457	}
 458
 459	if (obj->dma_buf) {
 460		get_dma_buf(obj->dma_buf);
 461		dmabuf = obj->dma_buf;
 462		goto out_have_obj;
 463	}
 464
 465	dmabuf = export_and_register_object(dev, obj, flags);
 466	if (IS_ERR(dmabuf)) {
 467		/* normally the created dma-buf takes ownership of the ref,
 468		 * but if that fails then drop the ref
 469		 */
 470		ret = PTR_ERR(dmabuf);
 471		mutex_unlock(&dev->object_name_lock);
 472		goto out;
 473	}
 474
 475out_have_obj:
 476	/*
 477	 * If we've exported this buffer then cheat and add it to the import list
 478	 * so we get the correct handle back. We must do this under the
 479	 * protection of dev->object_name_lock to ensure that a racing gem close
 480	 * ioctl doesn't miss to remove this buffer handle from the cache.
 481	 */
 482	ret = drm_prime_add_buf_handle(&file_priv->prime,
 483				       dmabuf, handle);
 484	mutex_unlock(&dev->object_name_lock);
 485	if (ret)
 486		goto fail_put_dmabuf;
 487
 488out_have_handle:
 489	ret = dma_buf_fd(dmabuf, flags);
 490	/*
 491	 * We must _not_ remove the buffer from the handle cache since the newly
 492	 * created dma buf is already linked in the global obj->dma_buf pointer,
 493	 * and that is invariant as long as a userspace gem handle exists.
 494	 * Closing the handle will clean out the cache anyway, so we don't leak.
 495	 */
 496	if (ret < 0) {
 497		goto fail_put_dmabuf;
 498	} else {
 499		*prime_fd = ret;
 500		ret = 0;
 501	}
 502
 503	goto out;
 504
 505fail_put_dmabuf:
 506	dma_buf_put(dmabuf);
 507out:
 508	drm_gem_object_put(obj);
 509out_unlock:
 510	mutex_unlock(&file_priv->prime.lock);
 511
 512	return ret;
 513}
 514EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
 515
 516int drm_prime_handle_to_fd_ioctl(struct drm_device *dev, void *data,
 517				 struct drm_file *file_priv)
 518{
 519	struct drm_prime_handle *args = data;
 
 
 
 
 520
 521	if (!dev->driver->prime_handle_to_fd)
 522		return -ENOSYS;
 523
 524	/* check flags are valid */
 525	if (args->flags & ~(DRM_CLOEXEC | DRM_RDWR))
 526		return -EINVAL;
 527
 528	return dev->driver->prime_handle_to_fd(dev, file_priv,
 529			args->handle, args->flags, &args->fd);
 530}
 531
 532/**
 533 * DOC: PRIME Helpers
 534 *
 535 * Drivers can implement &drm_gem_object_funcs.export and
 536 * &drm_driver.gem_prime_import in terms of simpler APIs by using the helper
 537 * functions drm_gem_prime_export() and drm_gem_prime_import(). These functions
 538 * implement dma-buf support in terms of some lower-level helpers, which are
 539 * again exported for drivers to use individually:
 540 *
 541 * Exporting buffers
 542 * ~~~~~~~~~~~~~~~~~
 543 *
 544 * Optional pinning of buffers is handled at dma-buf attach and detach time in
 545 * drm_gem_map_attach() and drm_gem_map_detach(). Backing storage itself is
 546 * handled by drm_gem_map_dma_buf() and drm_gem_unmap_dma_buf(), which relies on
 547 * &drm_gem_object_funcs.get_sg_table.
 548 *
 549 * For kernel-internal access there's drm_gem_dmabuf_vmap() and
 550 * drm_gem_dmabuf_vunmap(). Userspace mmap support is provided by
 551 * drm_gem_dmabuf_mmap().
 552 *
 553 * Note that these export helpers can only be used if the underlying backing
 554 * storage is fully coherent and either permanently pinned, or it is safe to pin
 555 * it indefinitely.
 556 *
 557 * FIXME: The underlying helper functions are named rather inconsistently.
 558 *
 559 * Importing buffers
 560 * ~~~~~~~~~~~~~~~~~
 561 *
 562 * Importing dma-bufs using drm_gem_prime_import() relies on
 563 * &drm_driver.gem_prime_import_sg_table.
 564 *
 565 * Note that similarly to the export helpers this permanently pins the
 566 * underlying backing storage. Which is ok for scanout, but is not the best
 567 * option for sharing lots of buffers for rendering.
 568 */
 569
 570/**
 571 * drm_gem_map_attach - dma_buf attach implementation for GEM
 572 * @dma_buf: buffer to attach device to
 573 * @attach: buffer attachment data
 574 *
 575 * Calls &drm_gem_object_funcs.pin for device specific handling. This can be
 576 * used as the &dma_buf_ops.attach callback. Must be used together with
 577 * drm_gem_map_detach().
 578 *
 579 * Returns 0 on success, negative error code on failure.
 580 */
 581int drm_gem_map_attach(struct dma_buf *dma_buf,
 582		       struct dma_buf_attachment *attach)
 583{
 584	struct drm_gem_object *obj = dma_buf->priv;
 585
 586	return drm_gem_pin(obj);
 587}
 588EXPORT_SYMBOL(drm_gem_map_attach);
 589
 590/**
 591 * drm_gem_map_detach - dma_buf detach implementation for GEM
 592 * @dma_buf: buffer to detach from
 593 * @attach: attachment to be detached
 594 *
 595 * Calls &drm_gem_object_funcs.pin for device specific handling.  Cleans up
 596 * &dma_buf_attachment from drm_gem_map_attach(). This can be used as the
 597 * &dma_buf_ops.detach callback.
 598 */
 599void drm_gem_map_detach(struct dma_buf *dma_buf,
 600			struct dma_buf_attachment *attach)
 601{
 602	struct drm_gem_object *obj = dma_buf->priv;
 603
 604	drm_gem_unpin(obj);
 605}
 606EXPORT_SYMBOL(drm_gem_map_detach);
 607
 608/**
 609 * drm_gem_map_dma_buf - map_dma_buf implementation for GEM
 610 * @attach: attachment whose scatterlist is to be returned
 611 * @dir: direction of DMA transfer
 612 *
 613 * Calls &drm_gem_object_funcs.get_sg_table and then maps the scatterlist. This
 614 * can be used as the &dma_buf_ops.map_dma_buf callback. Should be used together
 615 * with drm_gem_unmap_dma_buf().
 616 *
 617 * Returns:sg_table containing the scatterlist to be returned; returns ERR_PTR
 618 * on error. May return -EINTR if it is interrupted by a signal.
 619 */
 620struct sg_table *drm_gem_map_dma_buf(struct dma_buf_attachment *attach,
 621				     enum dma_data_direction dir)
 622{
 623	struct drm_gem_object *obj = attach->dmabuf->priv;
 624	struct sg_table *sgt;
 625	int ret;
 626
 627	if (WARN_ON(dir == DMA_NONE))
 628		return ERR_PTR(-EINVAL);
 629
 630	if (WARN_ON(!obj->funcs->get_sg_table))
 631		return ERR_PTR(-ENOSYS);
 632
 633	sgt = obj->funcs->get_sg_table(obj);
 634	if (IS_ERR(sgt))
 635		return sgt;
 636
 637	ret = dma_map_sgtable(attach->dev, sgt, dir,
 638			      DMA_ATTR_SKIP_CPU_SYNC);
 639	if (ret) {
 640		sg_free_table(sgt);
 641		kfree(sgt);
 642		sgt = ERR_PTR(ret);
 643	}
 644
 645	return sgt;
 646}
 647EXPORT_SYMBOL(drm_gem_map_dma_buf);
 648
 649/**
 650 * drm_gem_unmap_dma_buf - unmap_dma_buf implementation for GEM
 651 * @attach: attachment to unmap buffer from
 652 * @sgt: scatterlist info of the buffer to unmap
 653 * @dir: direction of DMA transfer
 654 *
 655 * This can be used as the &dma_buf_ops.unmap_dma_buf callback.
 656 */
 657void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 658			   struct sg_table *sgt,
 659			   enum dma_data_direction dir)
 660{
 661	if (!sgt)
 662		return;
 663
 664	dma_unmap_sgtable(attach->dev, sgt, dir, DMA_ATTR_SKIP_CPU_SYNC);
 665	sg_free_table(sgt);
 666	kfree(sgt);
 667}
 668EXPORT_SYMBOL(drm_gem_unmap_dma_buf);
 669
 670/**
 671 * drm_gem_dmabuf_vmap - dma_buf vmap implementation for GEM
 672 * @dma_buf: buffer to be mapped
 673 * @map: the virtual address of the buffer
 674 *
 675 * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap
 676 * callback. Calls into &drm_gem_object_funcs.vmap for device specific handling.
 677 * The kernel virtual address is returned in map.
 678 *
 679 * Returns 0 on success or a negative errno code otherwise.
 680 */
 681int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct iosys_map *map)
 682{
 683	struct drm_gem_object *obj = dma_buf->priv;
 684
 685	return drm_gem_vmap(obj, map);
 686}
 687EXPORT_SYMBOL(drm_gem_dmabuf_vmap);
 688
 689/**
 690 * drm_gem_dmabuf_vunmap - dma_buf vunmap implementation for GEM
 691 * @dma_buf: buffer to be unmapped
 692 * @map: the virtual address of the buffer
 693 *
 694 * Releases a kernel virtual mapping. This can be used as the
 695 * &dma_buf_ops.vunmap callback. Calls into &drm_gem_object_funcs.vunmap for device specific handling.
 696 */
 697void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct iosys_map *map)
 698{
 699	struct drm_gem_object *obj = dma_buf->priv;
 700
 701	drm_gem_vunmap(obj, map);
 
 702}
 703EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
 704
 705/**
 706 * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
 707 * @obj: GEM object
 708 * @vma: Virtual address range
 709 *
 710 * This function sets up a userspace mapping for PRIME exported buffers using
 711 * the same codepath that is used for regular GEM buffer mapping on the DRM fd.
 712 * The fake GEM offset is added to vma->vm_pgoff and &drm_driver->fops->mmap is
 713 * called to set up the mapping.
 714 *
 715 * Drivers can use this as their &drm_driver.gem_prime_mmap callback.
 
 
 716 */
 717int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
 718{
 719	struct drm_file *priv;
 720	struct file *fil;
 
 721	int ret;
 722
 723	/* Add the fake offset */
 724	vma->vm_pgoff += drm_vma_node_start(&obj->vma_node);
 725
 726	if (obj->funcs && obj->funcs->mmap) {
 727		vma->vm_ops = obj->funcs->vm_ops;
 728
 729		drm_gem_object_get(obj);
 730		ret = obj->funcs->mmap(obj, vma);
 731		if (ret) {
 732			drm_gem_object_put(obj);
 733			return ret;
 734		}
 735		vma->vm_private_data = obj;
 736		return 0;
 737	}
 738
 739	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 740	fil = kzalloc(sizeof(*fil), GFP_KERNEL);
 741	if (!priv || !fil) {
 742		ret = -ENOMEM;
 743		goto out;
 744	}
 745
 746	/* Used by drm_gem_mmap() to lookup the GEM object */
 747	priv->minor = obj->dev->primary;
 748	fil->private_data = priv;
 749
 750	ret = drm_vma_node_allow(&obj->vma_node, priv);
 751	if (ret)
 752		goto out;
 753
 754	ret = obj->dev->driver->fops->mmap(fil, vma);
 755
 756	drm_vma_node_revoke(&obj->vma_node, priv);
 757out:
 758	kfree(priv);
 759	kfree(fil);
 760
 761	return ret;
 762}
 763EXPORT_SYMBOL(drm_gem_prime_mmap);
 764
 765/**
 766 * drm_gem_dmabuf_mmap - dma_buf mmap implementation for GEM
 767 * @dma_buf: buffer to be mapped
 768 * @vma: virtual address range
 769 *
 770 * Provides memory mapping for the buffer. This can be used as the
 771 * &dma_buf_ops.mmap callback. It just forwards to &drm_driver.gem_prime_mmap,
 772 * which should be set to drm_gem_prime_mmap().
 773 *
 774 * FIXME: There's really no point to this wrapper, drivers which need anything
 775 * else but drm_gem_prime_mmap can roll their own &dma_buf_ops.mmap callback.
 776 *
 777 * Returns 0 on success or a negative error code on failure.
 778 */
 779int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma)
 780{
 781	struct drm_gem_object *obj = dma_buf->priv;
 782	struct drm_device *dev = obj->dev;
 783
 784	dma_resv_assert_held(dma_buf->resv);
 785
 786	if (!dev->driver->gem_prime_mmap)
 787		return -ENOSYS;
 788
 789	return dev->driver->gem_prime_mmap(obj, vma);
 790}
 791EXPORT_SYMBOL(drm_gem_dmabuf_mmap);
 792
 793static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
 794	.cache_sgt_mapping = true,
 795	.attach = drm_gem_map_attach,
 796	.detach = drm_gem_map_detach,
 797	.map_dma_buf = drm_gem_map_dma_buf,
 798	.unmap_dma_buf = drm_gem_unmap_dma_buf,
 799	.release = drm_gem_dmabuf_release,
 800	.mmap = drm_gem_dmabuf_mmap,
 801	.vmap = drm_gem_dmabuf_vmap,
 802	.vunmap = drm_gem_dmabuf_vunmap,
 803};
 804
 805/**
 806 * drm_prime_pages_to_sg - converts a page array into an sg list
 807 * @dev: DRM device
 808 * @pages: pointer to the array of page pointers to convert
 809 * @nr_pages: length of the page vector
 810 *
 811 * This helper creates an sg table object from a set of pages
 812 * the driver is responsible for mapping the pages into the
 813 * importers address space for use with dma_buf itself.
 814 *
 815 * This is useful for implementing &drm_gem_object_funcs.get_sg_table.
 816 */
 817struct sg_table *drm_prime_pages_to_sg(struct drm_device *dev,
 818				       struct page **pages, unsigned int nr_pages)
 819{
 820	struct sg_table *sg;
 821	size_t max_segment = 0;
 822	int err;
 823
 824	sg = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
 825	if (!sg)
 826		return ERR_PTR(-ENOMEM);
 827
 828	if (dev)
 829		max_segment = dma_max_mapping_size(dev->dev);
 830	if (max_segment == 0)
 831		max_segment = UINT_MAX;
 832	err = sg_alloc_table_from_pages_segment(sg, pages, nr_pages, 0,
 833						nr_pages << PAGE_SHIFT,
 834						max_segment, GFP_KERNEL);
 835	if (err) {
 836		kfree(sg);
 837		sg = ERR_PTR(err);
 838	}
 839	return sg;
 
 
 
 840}
 841EXPORT_SYMBOL(drm_prime_pages_to_sg);
 842
 843/**
 844 * drm_prime_get_contiguous_size - returns the contiguous size of the buffer
 845 * @sgt: sg_table describing the buffer to check
 846 *
 847 * This helper calculates the contiguous size in the DMA address space
 848 * of the buffer described by the provided sg_table.
 849 *
 850 * This is useful for implementing
 851 * &drm_gem_object_funcs.gem_prime_import_sg_table.
 852 */
 853unsigned long drm_prime_get_contiguous_size(struct sg_table *sgt)
 854{
 855	dma_addr_t expected = sg_dma_address(sgt->sgl);
 856	struct scatterlist *sg;
 857	unsigned long size = 0;
 858	int i;
 859
 860	for_each_sgtable_dma_sg(sgt, sg, i) {
 861		unsigned int len = sg_dma_len(sg);
 862
 863		if (!len)
 864			break;
 865		if (sg_dma_address(sg) != expected)
 866			break;
 867		expected += len;
 868		size += len;
 
 
 
 
 
 
 
 
 
 
 
 
 869	}
 870	return size;
 871}
 872EXPORT_SYMBOL(drm_prime_get_contiguous_size);
 873
 874/**
 875 * drm_gem_prime_export - helper library implementation of the export callback
 876 * @obj: GEM object to export
 877 * @flags: flags like DRM_CLOEXEC and DRM_RDWR
 878 *
 879 * This is the implementation of the &drm_gem_object_funcs.export functions for GEM drivers
 880 * using the PRIME helpers. It is used as the default in
 881 * drm_gem_prime_handle_to_fd().
 882 */
 883struct dma_buf *drm_gem_prime_export(struct drm_gem_object *obj,
 884				     int flags)
 885{
 886	struct drm_device *dev = obj->dev;
 887	struct dma_buf_export_info exp_info = {
 888		.exp_name = KBUILD_MODNAME, /* white lie for debug */
 889		.owner = dev->driver->fops->owner,
 890		.ops = &drm_gem_prime_dmabuf_ops,
 891		.size = obj->size,
 892		.flags = flags,
 893		.priv = obj,
 894		.resv = obj->resv,
 895	};
 896
 897	return drm_gem_dmabuf_export(dev, &exp_info);
 898}
 899EXPORT_SYMBOL(drm_gem_prime_export);
 900
 901/**
 902 * drm_gem_prime_import_dev - core implementation of the import callback
 903 * @dev: drm_device to import into
 904 * @dma_buf: dma-buf object to import
 905 * @attach_dev: struct device to dma_buf attach
 906 *
 907 * This is the core of drm_gem_prime_import(). It's designed to be called by
 908 * drivers who want to use a different device structure than &drm_device.dev for
 909 * attaching via dma_buf. This function calls
 910 * &drm_driver.gem_prime_import_sg_table internally.
 911 *
 912 * Drivers must arrange to call drm_prime_gem_destroy() from their
 913 * &drm_gem_object_funcs.free hook when using this function.
 914 */
 915struct drm_gem_object *drm_gem_prime_import_dev(struct drm_device *dev,
 916					    struct dma_buf *dma_buf,
 917					    struct device *attach_dev)
 918{
 919	struct dma_buf_attachment *attach;
 920	struct sg_table *sgt;
 921	struct drm_gem_object *obj;
 922	int ret;
 923
 924	if (dma_buf->ops == &drm_gem_prime_dmabuf_ops) {
 925		obj = dma_buf->priv;
 926		if (obj->dev == dev) {
 927			/*
 928			 * Importing dmabuf exported from out own gem increases
 929			 * refcount on gem itself instead of f_count of dmabuf.
 930			 */
 931			drm_gem_object_get(obj);
 932			return obj;
 933		}
 934	}
 935
 936	if (!dev->driver->gem_prime_import_sg_table)
 937		return ERR_PTR(-EINVAL);
 938
 939	attach = dma_buf_attach(dma_buf, attach_dev);
 940	if (IS_ERR(attach))
 941		return ERR_CAST(attach);
 942
 943	get_dma_buf(dma_buf);
 944
 945	sgt = dma_buf_map_attachment_unlocked(attach, DMA_BIDIRECTIONAL);
 946	if (IS_ERR(sgt)) {
 947		ret = PTR_ERR(sgt);
 948		goto fail_detach;
 949	}
 950
 951	obj = dev->driver->gem_prime_import_sg_table(dev, attach, sgt);
 952	if (IS_ERR(obj)) {
 953		ret = PTR_ERR(obj);
 954		goto fail_unmap;
 955	}
 956
 957	obj->import_attach = attach;
 958	obj->resv = dma_buf->resv;
 959
 960	return obj;
 961
 962fail_unmap:
 963	dma_buf_unmap_attachment_unlocked(attach, sgt, DMA_BIDIRECTIONAL);
 964fail_detach:
 965	dma_buf_detach(dma_buf, attach);
 966	dma_buf_put(dma_buf);
 
 
 967
 968	return ERR_PTR(ret);
 
 
 
 969}
 970EXPORT_SYMBOL(drm_gem_prime_import_dev);
 971
 972/**
 973 * drm_gem_prime_import - helper library implementation of the import callback
 974 * @dev: drm_device to import into
 975 * @dma_buf: dma-buf object to import
 976 *
 977 * This is the implementation of the gem_prime_import functions for GEM drivers
 978 * using the PRIME helpers. Drivers can use this as their
 979 * &drm_driver.gem_prime_import implementation. It is used as the default
 980 * implementation in drm_gem_prime_fd_to_handle().
 981 *
 982 * Drivers must arrange to call drm_prime_gem_destroy() from their
 983 * &drm_gem_object_funcs.free hook when using this function.
 984 */
 985struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 986					    struct dma_buf *dma_buf)
 987{
 988	return drm_gem_prime_import_dev(dev, dma_buf, dev->dev);
 
 
 
 
 989}
 990EXPORT_SYMBOL(drm_gem_prime_import);
 991
 992/**
 993 * drm_prime_sg_to_page_array - convert an sg table into a page array
 994 * @sgt: scatter-gather table to convert
 995 * @pages: array of page pointers to store the pages in
 996 * @max_entries: size of the passed-in array
 997 *
 998 * Exports an sg table into an array of pages.
 999 *
1000 * This function is deprecated and strongly discouraged to be used.
1001 * The page array is only useful for page faults and those can corrupt fields
1002 * in the struct page if they are not handled by the exporting driver.
1003 */
1004int __deprecated drm_prime_sg_to_page_array(struct sg_table *sgt,
1005					    struct page **pages,
1006					    int max_entries)
1007{
1008	struct sg_page_iter page_iter;
1009	struct page **p = pages;
1010
1011	for_each_sgtable_page(sgt, &page_iter, 0) {
1012		if (WARN_ON(p - pages >= max_entries))
1013			return -1;
1014		*p++ = sg_page_iter_page(&page_iter);
1015	}
 
 
1016	return 0;
1017}
1018EXPORT_SYMBOL(drm_prime_sg_to_page_array);
1019
1020/**
1021 * drm_prime_sg_to_dma_addr_array - convert an sg table into a dma addr array
1022 * @sgt: scatter-gather table to convert
1023 * @addrs: array to store the dma bus address of each page
1024 * @max_entries: size of both the passed-in arrays
1025 *
1026 * Exports an sg table into an array of addresses.
1027 *
1028 * Drivers should use this in their &drm_driver.gem_prime_import_sg_table
1029 * implementation.
1030 */
1031int drm_prime_sg_to_dma_addr_array(struct sg_table *sgt, dma_addr_t *addrs,
1032				   int max_entries)
1033{
1034	struct sg_dma_page_iter dma_iter;
1035	dma_addr_t *a = addrs;
1036
1037	for_each_sgtable_dma_page(sgt, &dma_iter, 0) {
1038		if (WARN_ON(a - addrs >= max_entries))
1039			return -1;
1040		*a++ = sg_page_iter_dma_address(&dma_iter);
 
1041	}
1042	return 0;
1043}
1044EXPORT_SYMBOL(drm_prime_sg_to_dma_addr_array);
1045
1046/**
1047 * drm_prime_gem_destroy - helper to clean up a PRIME-imported GEM object
1048 * @obj: GEM object which was created from a dma-buf
1049 * @sg: the sg-table which was pinned at import time
1050 *
1051 * This is the cleanup functions which GEM drivers need to call when they use
1052 * drm_gem_prime_import() or drm_gem_prime_import_dev() to import dma-bufs.
1053 */
1054void drm_prime_gem_destroy(struct drm_gem_object *obj, struct sg_table *sg)
1055{
1056	struct dma_buf_attachment *attach;
1057	struct dma_buf *dma_buf;
1058
1059	attach = obj->import_attach;
1060	if (sg)
1061		dma_buf_unmap_attachment_unlocked(attach, sg, DMA_BIDIRECTIONAL);
1062	dma_buf = attach->dmabuf;
1063	dma_buf_detach(attach->dmabuf, attach);
1064	/* remove the reference */
1065	dma_buf_put(dma_buf);
 
1066}
1067EXPORT_SYMBOL(drm_prime_gem_destroy);