1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Framework for buffer objects that can be shared across devices/subsystems.
   4 *
   5 * Copyright(C) 2011 Linaro Limited. All rights reserved.
   6 * Author: Sumit Semwal <sumit.semwal@ti.com>
   7 *
   8 * Many thanks to linaro-mm-sig list, and specially
   9 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and
  10 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and
  11 * refining of this idea.
 
 
 
 
 
 
 
 
 
 
 
 
  12 */
  13
  14#include <linux/fs.h>
  15#include <linux/slab.h>
  16#include <linux/dma-buf.h>
  17#include <linux/dma-fence.h>
  18#include <linux/dma-fence-unwrap.h>
  19#include <linux/anon_inodes.h>
  20#include <linux/export.h>
  21#include <linux/debugfs.h>
  22#include <linux/module.h>
  23#include <linux/seq_file.h>
  24#include <linux/sync_file.h>
  25#include <linux/poll.h>
  26#include <linux/dma-resv.h>
  27#include <linux/mm.h>
  28#include <linux/mount.h>
  29#include <linux/pseudo_fs.h>
  30
  31#include <uapi/linux/dma-buf.h>
  32#include <uapi/linux/magic.h>
  33
  34#include "dma-buf-sysfs-stats.h"
  35
  36static inline int is_dma_buf_file(struct file *);
  37
  38#if IS_ENABLED(CONFIG_DEBUG_FS)
  39static DEFINE_MUTEX(debugfs_list_mutex);
  40static LIST_HEAD(debugfs_list);
  41
  42static void __dma_buf_debugfs_list_add(struct dma_buf *dmabuf)
  43{
  44	mutex_lock(&debugfs_list_mutex);
  45	list_add(&dmabuf->list_node, &debugfs_list);
  46	mutex_unlock(&debugfs_list_mutex);
  47}
  48
  49static void __dma_buf_debugfs_list_del(struct dma_buf *dmabuf)
  50{
  51	if (!dmabuf)
  52		return;
  53
  54	mutex_lock(&debugfs_list_mutex);
  55	list_del(&dmabuf->list_node);
  56	mutex_unlock(&debugfs_list_mutex);
  57}
  58#else
  59static void __dma_buf_debugfs_list_add(struct dma_buf *dmabuf)
  60{
  61}
  62
  63static void __dma_buf_debugfs_list_del(struct dma_buf *dmabuf)
  64{
  65}
  66#endif
  67
  68static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
  69{
  70	struct dma_buf *dmabuf;
  71	char name[DMA_BUF_NAME_LEN];
  72	ssize_t ret = 0;
  73
  74	dmabuf = dentry->d_fsdata;
  75	spin_lock(&dmabuf->name_lock);
  76	if (dmabuf->name)
  77		ret = strscpy(name, dmabuf->name, sizeof(name));
  78	spin_unlock(&dmabuf->name_lock);
  79
  80	return dynamic_dname(buffer, buflen, "/%s:%s",
  81			     dentry->d_name.name, ret > 0 ? name : "");
  82}
  83
  84static void dma_buf_release(struct dentry *dentry)
  85{
  86	struct dma_buf *dmabuf;
  87
  88	dmabuf = dentry->d_fsdata;
  89	if (unlikely(!dmabuf))
  90		return;
  91
  92	BUG_ON(dmabuf->vmapping_counter);
  93
  94	/*
  95	 * If you hit this BUG() it could mean:
  96	 * * There's a file reference imbalance in dma_buf_poll / dma_buf_poll_cb or somewhere else
  97	 * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback
 
 
 
  98	 */
  99	BUG_ON(dmabuf->cb_in.active || dmabuf->cb_out.active);
 100
 101	dma_buf_stats_teardown(dmabuf);
 102	dmabuf->ops->release(dmabuf);
 103
 104	if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
 105		dma_resv_fini(dmabuf->resv);
 
 
 
 
 106
 107	WARN_ON(!list_empty(&dmabuf->attachments));
 108	module_put(dmabuf->owner);
 109	kfree(dmabuf->name);
 110	kfree(dmabuf);
 111}
 112
 113static int dma_buf_file_release(struct inode *inode, struct file *file)
 114{
 115	if (!is_dma_buf_file(file))
 116		return -EINVAL;
 117
 118	__dma_buf_debugfs_list_del(file->private_data);
 119
 120	return 0;
 121}
 122
 123static const struct dentry_operations dma_buf_dentry_ops = {
 124	.d_dname = dmabuffs_dname,
 125	.d_release = dma_buf_release,
 126};
 127
 128static struct vfsmount *dma_buf_mnt;
 129
 130static int dma_buf_fs_init_context(struct fs_context *fc)
 131{
 132	struct pseudo_fs_context *ctx;
 133
 134	ctx = init_pseudo(fc, DMA_BUF_MAGIC);
 135	if (!ctx)
 136		return -ENOMEM;
 137	ctx->dops = &dma_buf_dentry_ops;
 138	return 0;
 139}
 140
 141static struct file_system_type dma_buf_fs_type = {
 142	.name = "dmabuf",
 143	.init_fs_context = dma_buf_fs_init_context,
 144	.kill_sb = kill_anon_super,
 145};
 146
 147static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 148{
 149	struct dma_buf *dmabuf;
 150
 151	if (!is_dma_buf_file(file))
 152		return -EINVAL;
 153
 154	dmabuf = file->private_data;
 155
 156	/* check if buffer supports mmap */
 157	if (!dmabuf->ops->mmap)
 158		return -EINVAL;
 159
 160	/* check for overflowing the buffer's size */
 161	if (vma->vm_pgoff + vma_pages(vma) >
 162	    dmabuf->size >> PAGE_SHIFT)
 163		return -EINVAL;
 164
 165	return dmabuf->ops->mmap(dmabuf, vma);
 166}
 167
 168static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
 169{
 170	struct dma_buf *dmabuf;
 171	loff_t base;
 172
 173	if (!is_dma_buf_file(file))
 174		return -EBADF;
 175
 176	dmabuf = file->private_data;
 177
 178	/* only support discovering the end of the buffer,
 179	 * but also allow SEEK_SET to maintain the idiomatic
 180	 * SEEK_END(0), SEEK_CUR(0) pattern.
 181	 */
 182	if (whence == SEEK_END)
 183		base = dmabuf->size;
 184	else if (whence == SEEK_SET)
 185		base = 0;
 186	else
 187		return -EINVAL;
 188
 189	if (offset != 0)
 190		return -EINVAL;
 191
 192	return base + offset;
 193}
 194
 195/**
 196 * DOC: implicit fence polling
 197 *
 198 * To support cross-device and cross-driver synchronization of buffer access
 199 * implicit fences (represented internally in the kernel with &struct dma_fence)
 200 * can be attached to a &dma_buf. The glue for that and a few related things are
 201 * provided in the &dma_resv structure.
 202 *
 203 * Userspace can query the state of these implicitly tracked fences using poll()
 204 * and related system calls:
 205 *
 206 * - Checking for EPOLLIN, i.e. read access, can be use to query the state of the
 207 *   most recent write or exclusive fence.
 208 *
 209 * - Checking for EPOLLOUT, i.e. write access, can be used to query the state of
 210 *   all attached fences, shared and exclusive ones.
 211 *
 212 * Note that this only signals the completion of the respective fences, i.e. the
 213 * DMA transfers are complete. Cache flushing and any other necessary
 214 * preparations before CPU access can begin still need to happen.
 215 *
 216 * As an alternative to poll(), the set of fences on DMA buffer can be
 217 * exported as a &sync_file using &dma_buf_sync_file_export.
 218 */
 219
 220static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)
 221{
 222	struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;
 223	struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll);
 224	unsigned long flags;
 225
 226	spin_lock_irqsave(&dcb->poll->lock, flags);
 227	wake_up_locked_poll(dcb->poll, dcb->active);
 228	dcb->active = 0;
 229	spin_unlock_irqrestore(&dcb->poll->lock, flags);
 230	dma_fence_put(fence);
 231	/* Paired with get_file in dma_buf_poll */
 232	fput(dmabuf->file);
 233}
 234
 235static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,
 236				struct dma_buf_poll_cb_t *dcb)
 237{
 238	struct dma_resv_iter cursor;
 239	struct dma_fence *fence;
 240	int r;
 241
 242	dma_resv_for_each_fence(&cursor, resv, dma_resv_usage_rw(write),
 243				fence) {
 244		dma_fence_get(fence);
 245		r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);
 246		if (!r)
 247			return true;
 248		dma_fence_put(fence);
 249	}
 250
 251	return false;
 252}
 253
 254static __poll_t dma_buf_poll(struct file *file, poll_table *poll)
 255{
 256	struct dma_buf *dmabuf;
 257	struct dma_resv *resv;
 258	__poll_t events;
 
 
 
 259
 260	dmabuf = file->private_data;
 261	if (!dmabuf || !dmabuf->resv)
 262		return EPOLLERR;
 263
 264	resv = dmabuf->resv;
 265
 266	poll_wait(file, &dmabuf->poll, poll);
 267
 268	events = poll_requested_events(poll) & (EPOLLIN | EPOLLOUT);
 269	if (!events)
 270		return 0;
 271
 272	dma_resv_lock(resv, NULL);
 
 
 
 
 
 
 
 
 
 
 
 
 
 273
 274	if (events & EPOLLOUT) {
 275		struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_out;
 
 
 
 
 276
 277		/* Check that callback isn't busy */
 278		spin_lock_irq(&dmabuf->poll.lock);
 279		if (dcb->active)
 280			events &= ~EPOLLOUT;
 281		else
 282			dcb->active = EPOLLOUT;
 
 283		spin_unlock_irq(&dmabuf->poll.lock);
 284
 285		if (events & EPOLLOUT) {
 286			/* Paired with fput in dma_buf_poll_cb */
 287			get_file(dmabuf->file);
 288
 289			if (!dma_buf_poll_add_cb(resv, true, dcb))
 290				/* No callback queued, wake up any other waiters */
 291				dma_buf_poll_cb(NULL, &dcb->cb);
 292			else
 293				events &= ~EPOLLOUT;
 
 
 
 
 
 
 
 
 
 
 294		}
 295	}
 296
 297	if (events & EPOLLIN) {
 298		struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_in;
 
 299
 300		/* Check that callback isn't busy */
 301		spin_lock_irq(&dmabuf->poll.lock);
 302		if (dcb->active)
 303			events &= ~EPOLLIN;
 304		else
 305			dcb->active = EPOLLIN;
 306		spin_unlock_irq(&dmabuf->poll.lock);
 307
 308		if (events & EPOLLIN) {
 309			/* Paired with fput in dma_buf_poll_cb */
 310			get_file(dmabuf->file);
 311
 312			if (!dma_buf_poll_add_cb(resv, false, dcb))
 313				/* No callback queued, wake up any other waiters */
 314				dma_buf_poll_cb(NULL, &dcb->cb);
 315			else
 316				events &= ~EPOLLIN;
 317		}
 318	}
 319
 320	dma_resv_unlock(resv);
 321	return events;
 322}
 323
 324/**
 325 * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.
 326 * It could support changing the name of the dma-buf if the same
 327 * piece of memory is used for multiple purpose between different devices.
 328 *
 329 * @dmabuf: [in]     dmabuf buffer that will be renamed.
 330 * @buf:    [in]     A piece of userspace memory that contains the name of
 331 *                   the dma-buf.
 332 *
 333 * Returns 0 on success. If the dma-buf buffer is already attached to
 334 * devices, return -EBUSY.
 335 *
 336 */
 337static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)
 338{
 339	char *name = strndup_user(buf, DMA_BUF_NAME_LEN);
 340
 341	if (IS_ERR(name))
 342		return PTR_ERR(name);
 343
 344	spin_lock(&dmabuf->name_lock);
 345	kfree(dmabuf->name);
 346	dmabuf->name = name;
 347	spin_unlock(&dmabuf->name_lock);
 348
 349	return 0;
 350}
 351
 352#if IS_ENABLED(CONFIG_SYNC_FILE)
 353static long dma_buf_export_sync_file(struct dma_buf *dmabuf,
 354				     void __user *user_data)
 355{
 356	struct dma_buf_export_sync_file arg;
 357	enum dma_resv_usage usage;
 358	struct dma_fence *fence = NULL;
 359	struct sync_file *sync_file;
 360	int fd, ret;
 361
 362	if (copy_from_user(&arg, user_data, sizeof(arg)))
 363		return -EFAULT;
 364
 365	if (arg.flags & ~DMA_BUF_SYNC_RW)
 366		return -EINVAL;
 367
 368	if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
 369		return -EINVAL;
 370
 371	fd = get_unused_fd_flags(O_CLOEXEC);
 372	if (fd < 0)
 373		return fd;
 374
 375	usage = dma_resv_usage_rw(arg.flags & DMA_BUF_SYNC_WRITE);
 376	ret = dma_resv_get_singleton(dmabuf->resv, usage, &fence);
 377	if (ret)
 378		goto err_put_fd;
 379
 380	if (!fence)
 381		fence = dma_fence_get_stub();
 382
 383	sync_file = sync_file_create(fence);
 384
 385	dma_fence_put(fence);
 386
 387	if (!sync_file) {
 388		ret = -ENOMEM;
 389		goto err_put_fd;
 390	}
 391
 392	arg.fd = fd;
 393	if (copy_to_user(user_data, &arg, sizeof(arg))) {
 394		ret = -EFAULT;
 395		goto err_put_file;
 396	}
 397
 398	fd_install(fd, sync_file->file);
 399
 400	return 0;
 401
 402err_put_file:
 403	fput(sync_file->file);
 404err_put_fd:
 405	put_unused_fd(fd);
 406	return ret;
 407}
 408
 409static long dma_buf_import_sync_file(struct dma_buf *dmabuf,
 410				     const void __user *user_data)
 411{
 412	struct dma_buf_import_sync_file arg;
 413	struct dma_fence *fence, *f;
 414	enum dma_resv_usage usage;
 415	struct dma_fence_unwrap iter;
 416	unsigned int num_fences;
 417	int ret = 0;
 418
 419	if (copy_from_user(&arg, user_data, sizeof(arg)))
 420		return -EFAULT;
 421
 422	if (arg.flags & ~DMA_BUF_SYNC_RW)
 423		return -EINVAL;
 424
 425	if ((arg.flags & DMA_BUF_SYNC_RW) == 0)
 426		return -EINVAL;
 427
 428	fence = sync_file_get_fence(arg.fd);
 429	if (!fence)
 430		return -EINVAL;
 431
 432	usage = (arg.flags & DMA_BUF_SYNC_WRITE) ? DMA_RESV_USAGE_WRITE :
 433						   DMA_RESV_USAGE_READ;
 434
 435	num_fences = 0;
 436	dma_fence_unwrap_for_each(f, &iter, fence)
 437		++num_fences;
 438
 439	if (num_fences > 0) {
 440		dma_resv_lock(dmabuf->resv, NULL);
 441
 442		ret = dma_resv_reserve_fences(dmabuf->resv, num_fences);
 443		if (!ret) {
 444			dma_fence_unwrap_for_each(f, &iter, fence)
 445				dma_resv_add_fence(dmabuf->resv, f, usage);
 446		}
 447
 448		dma_resv_unlock(dmabuf->resv);
 
 
 449	}
 450
 451	dma_fence_put(fence);
 452
 453	return ret;
 454}
 455#endif
 456
 457static long dma_buf_ioctl(struct file *file,
 458			  unsigned int cmd, unsigned long arg)
 459{
 460	struct dma_buf *dmabuf;
 461	struct dma_buf_sync sync;
 462	enum dma_data_direction direction;
 463	int ret;
 464
 465	dmabuf = file->private_data;
 466
 467	switch (cmd) {
 468	case DMA_BUF_IOCTL_SYNC:
 469		if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))
 470			return -EFAULT;
 471
 472		if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)
 473			return -EINVAL;
 474
 475		switch (sync.flags & DMA_BUF_SYNC_RW) {
 476		case DMA_BUF_SYNC_READ:
 477			direction = DMA_FROM_DEVICE;
 478			break;
 479		case DMA_BUF_SYNC_WRITE:
 480			direction = DMA_TO_DEVICE;
 481			break;
 482		case DMA_BUF_SYNC_RW:
 483			direction = DMA_BIDIRECTIONAL;
 484			break;
 485		default:
 486			return -EINVAL;
 487		}
 488
 489		if (sync.flags & DMA_BUF_SYNC_END)
 490			ret = dma_buf_end_cpu_access(dmabuf, direction);
 491		else
 492			ret = dma_buf_begin_cpu_access(dmabuf, direction);
 493
 494		return ret;
 495
 496	case DMA_BUF_SET_NAME_A:
 497	case DMA_BUF_SET_NAME_B:
 498		return dma_buf_set_name(dmabuf, (const char __user *)arg);
 499
 500#if IS_ENABLED(CONFIG_SYNC_FILE)
 501	case DMA_BUF_IOCTL_EXPORT_SYNC_FILE:
 502		return dma_buf_export_sync_file(dmabuf, (void __user *)arg);
 503	case DMA_BUF_IOCTL_IMPORT_SYNC_FILE:
 504		return dma_buf_import_sync_file(dmabuf, (const void __user *)arg);
 505#endif
 506
 507	default:
 508		return -ENOTTY;
 509	}
 510}
 511
 512static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)
 513{
 514	struct dma_buf *dmabuf = file->private_data;
 515
 516	seq_printf(m, "size:\t%zu\n", dmabuf->size);
 517	/* Don't count the temporary reference taken inside procfs seq_show */
 518	seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);
 519	seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);
 520	spin_lock(&dmabuf->name_lock);
 521	if (dmabuf->name)
 522		seq_printf(m, "name:\t%s\n", dmabuf->name);
 523	spin_unlock(&dmabuf->name_lock);
 524}
 525
 526static const struct file_operations dma_buf_fops = {
 527	.release	= dma_buf_file_release,
 528	.mmap		= dma_buf_mmap_internal,
 529	.llseek		= dma_buf_llseek,
 530	.poll		= dma_buf_poll,
 531	.unlocked_ioctl	= dma_buf_ioctl,
 532	.compat_ioctl	= compat_ptr_ioctl,
 533	.show_fdinfo	= dma_buf_show_fdinfo,
 534};
 535
 536/*
 537 * is_dma_buf_file - Check if struct file* is associated with dma_buf
 538 */
 539static inline int is_dma_buf_file(struct file *file)
 540{
 541	return file->f_op == &dma_buf_fops;
 542}
 543
 544static struct file *dma_buf_getfile(size_t size, int flags)
 545{
 546	static atomic64_t dmabuf_inode = ATOMIC64_INIT(0);
 547	struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);
 548	struct file *file;
 549
 550	if (IS_ERR(inode))
 551		return ERR_CAST(inode);
 552
 553	inode->i_size = size;
 554	inode_set_bytes(inode, size);
 555
 556	/*
 557	 * The ->i_ino acquired from get_next_ino() is not unique thus
 558	 * not suitable for using it as dentry name by dmabuf stats.
 559	 * Override ->i_ino with the unique and dmabuffs specific
 560	 * value.
 561	 */
 562	inode->i_ino = atomic64_inc_return(&dmabuf_inode);
 563	flags &= O_ACCMODE | O_NONBLOCK;
 564	file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf",
 565				 flags, &dma_buf_fops);
 566	if (IS_ERR(file))
 567		goto err_alloc_file;
 568
 569	return file;
 570
 571err_alloc_file:
 572	iput(inode);
 573	return file;
 574}
 575
 576/**
 577 * DOC: dma buf device access
 578 *
 579 * For device DMA access to a shared DMA buffer the usual sequence of operations
 580 * is fairly simple:
 581 *
 582 * 1. The exporter defines his exporter instance using
 583 *    DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private
 584 *    buffer object into a &dma_buf. It then exports that &dma_buf to userspace
 585 *    as a file descriptor by calling dma_buf_fd().
 586 *
 587 * 2. Userspace passes this file-descriptors to all drivers it wants this buffer
 588 *    to share with: First the file descriptor is converted to a &dma_buf using
 589 *    dma_buf_get(). Then the buffer is attached to the device using
 590 *    dma_buf_attach().
 591 *
 592 *    Up to this stage the exporter is still free to migrate or reallocate the
 593 *    backing storage.
 594 *
 595 * 3. Once the buffer is attached to all devices userspace can initiate DMA
 596 *    access to the shared buffer. In the kernel this is done by calling
 597 *    dma_buf_map_attachment() and dma_buf_unmap_attachment().
 598 *
 599 * 4. Once a driver is done with a shared buffer it needs to call
 600 *    dma_buf_detach() (after cleaning up any mappings) and then release the
 601 *    reference acquired with dma_buf_get() by calling dma_buf_put().
 602 *
 603 * For the detailed semantics exporters are expected to implement see
 604 * &dma_buf_ops.
 605 */
 606
 607/**
 608 * dma_buf_export - Creates a new dma_buf, and associates an anon file
 609 * with this buffer, so it can be exported.
 610 * Also connect the allocator specific data and ops to the buffer.
 611 * Additionally, provide a name string for exporter; useful in debugging.
 612 *
 613 * @exp_info:	[in]	holds all the export related information provided
 614 *			by the exporter. see &struct dma_buf_export_info
 615 *			for further details.
 616 *
 617 * Returns, on success, a newly created struct dma_buf object, which wraps the
 618 * supplied private data and operations for struct dma_buf_ops. On either
 619 * missing ops, or error in allocating struct dma_buf, will return negative
 620 * error.
 621 *
 622 * For most cases the easiest way to create @exp_info is through the
 623 * %DEFINE_DMA_BUF_EXPORT_INFO macro.
 624 */
 625struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 626{
 627	struct dma_buf *dmabuf;
 628	struct dma_resv *resv = exp_info->resv;
 629	struct file *file;
 630	size_t alloc_size = sizeof(struct dma_buf);
 631	int ret;
 632
 633	if (WARN_ON(!exp_info->priv || !exp_info->ops
 634		    || !exp_info->ops->map_dma_buf
 635		    || !exp_info->ops->unmap_dma_buf
 636		    || !exp_info->ops->release))
 637		return ERR_PTR(-EINVAL);
 638
 639	if (WARN_ON(exp_info->ops->cache_sgt_mapping &&
 640		    (exp_info->ops->pin || exp_info->ops->unpin)))
 641		return ERR_PTR(-EINVAL);
 642
 643	if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))
 
 
 
 
 
 
 
 644		return ERR_PTR(-EINVAL);
 
 645
 646	if (!try_module_get(exp_info->owner))
 647		return ERR_PTR(-ENOENT);
 648
 649	file = dma_buf_getfile(exp_info->size, exp_info->flags);
 650	if (IS_ERR(file)) {
 651		ret = PTR_ERR(file);
 652		goto err_module;
 653	}
 654
 655	if (!exp_info->resv)
 656		alloc_size += sizeof(struct dma_resv);
 657	else
 658		/* prevent &dma_buf[1] == dma_buf->resv */
 659		alloc_size += 1;
 660	dmabuf = kzalloc(alloc_size, GFP_KERNEL);
 661	if (!dmabuf) {
 662		ret = -ENOMEM;
 663		goto err_file;
 664	}
 665
 666	dmabuf->priv = exp_info->priv;
 667	dmabuf->ops = exp_info->ops;
 668	dmabuf->size = exp_info->size;
 669	dmabuf->exp_name = exp_info->exp_name;
 670	dmabuf->owner = exp_info->owner;
 671	spin_lock_init(&dmabuf->name_lock);
 672	init_waitqueue_head(&dmabuf->poll);
 673	dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;
 674	dmabuf->cb_in.active = dmabuf->cb_out.active = 0;
 675	INIT_LIST_HEAD(&dmabuf->attachments);
 676
 677	if (!resv) {
 678		dmabuf->resv = (struct dma_resv *)&dmabuf[1];
 679		dma_resv_init(dmabuf->resv);
 680	} else {
 681		dmabuf->resv = resv;
 682	}
 
 683
 684	ret = dma_buf_stats_setup(dmabuf, file);
 685	if (ret)
 686		goto err_dmabuf;
 
 
 
 687
 688	file->private_data = dmabuf;
 689	file->f_path.dentry->d_fsdata = dmabuf;
 690	dmabuf->file = file;
 691
 692	__dma_buf_debugfs_list_add(dmabuf);
 
 
 
 
 
 693
 694	return dmabuf;
 695
 696err_dmabuf:
 697	if (!resv)
 698		dma_resv_fini(dmabuf->resv);
 699	kfree(dmabuf);
 700err_file:
 701	fput(file);
 702err_module:
 703	module_put(exp_info->owner);
 704	return ERR_PTR(ret);
 705}
 706EXPORT_SYMBOL_NS_GPL(dma_buf_export, "DMA_BUF");
 707
 708/**
 709 * dma_buf_fd - returns a file descriptor for the given struct dma_buf
 710 * @dmabuf:	[in]	pointer to dma_buf for which fd is required.
 711 * @flags:      [in]    flags to give to fd
 712 *
 713 * On success, returns an associated 'fd'. Else, returns error.
 714 */
 715int dma_buf_fd(struct dma_buf *dmabuf, int flags)
 716{
 717	int fd;
 718
 719	if (!dmabuf || !dmabuf->file)
 720		return -EINVAL;
 721
 722	fd = get_unused_fd_flags(flags);
 723	if (fd < 0)
 724		return fd;
 725
 726	fd_install(fd, dmabuf->file);
 727
 728	return fd;
 729}
 730EXPORT_SYMBOL_NS_GPL(dma_buf_fd, "DMA_BUF");
 731
 732/**
 733 * dma_buf_get - returns the struct dma_buf related to an fd
 734 * @fd:	[in]	fd associated with the struct dma_buf to be returned
 735 *
 736 * On success, returns the struct dma_buf associated with an fd; uses
 737 * file's refcounting done by fget to increase refcount. returns ERR_PTR
 738 * otherwise.
 739 */
 740struct dma_buf *dma_buf_get(int fd)
 741{
 742	struct file *file;
 743
 744	file = fget(fd);
 745
 746	if (!file)
 747		return ERR_PTR(-EBADF);
 748
 749	if (!is_dma_buf_file(file)) {
 750		fput(file);
 751		return ERR_PTR(-EINVAL);
 752	}
 753
 754	return file->private_data;
 755}
 756EXPORT_SYMBOL_NS_GPL(dma_buf_get, "DMA_BUF");
 757
 758/**
 759 * dma_buf_put - decreases refcount of the buffer
 760 * @dmabuf:	[in]	buffer to reduce refcount of
 761 *
 762 * Uses file's refcounting done implicitly by fput().
 763 *
 764 * If, as a result of this call, the refcount becomes 0, the 'release' file
 765 * operation related to this fd is called. It calls &dma_buf_ops.release vfunc
 766 * in turn, and frees the memory allocated for dmabuf when exported.
 767 */
 768void dma_buf_put(struct dma_buf *dmabuf)
 769{
 770	if (WARN_ON(!dmabuf || !dmabuf->file))
 771		return;
 772
 773	fput(dmabuf->file);
 774}
 775EXPORT_SYMBOL_NS_GPL(dma_buf_put, "DMA_BUF");
 776
 777static void mangle_sg_table(struct sg_table *sg_table)
 778{
 779#ifdef CONFIG_DMABUF_DEBUG
 780	int i;
 781	struct scatterlist *sg;
 782
 783	/* To catch abuse of the underlying struct page by importers mix
 784	 * up the bits, but take care to preserve the low SG_ bits to
 785	 * not corrupt the sgt. The mixing is undone in __unmap_dma_buf
 786	 * before passing the sgt back to the exporter.
 787	 */
 788	for_each_sgtable_sg(sg_table, sg, i)
 789		sg->page_link ^= ~0xffUL;
 790#endif
 791
 792}
 793static struct sg_table *__map_dma_buf(struct dma_buf_attachment *attach,
 794				       enum dma_data_direction direction)
 795{
 796	struct sg_table *sg_table;
 797	signed long ret;
 798
 799	sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);
 800	if (IS_ERR_OR_NULL(sg_table))
 801		return sg_table;
 802
 803	if (!dma_buf_attachment_is_dynamic(attach)) {
 804		ret = dma_resv_wait_timeout(attach->dmabuf->resv,
 805					    DMA_RESV_USAGE_KERNEL, true,
 806					    MAX_SCHEDULE_TIMEOUT);
 807		if (ret < 0) {
 808			attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,
 809							   direction);
 810			return ERR_PTR(ret);
 811		}
 812	}
 813
 814	mangle_sg_table(sg_table);
 815	return sg_table;
 816}
 817
 818/**
 819 * DOC: locking convention
 820 *
 821 * In order to avoid deadlock situations between dma-buf exports and importers,
 822 * all dma-buf API users must follow the common dma-buf locking convention.
 823 *
 824 * Convention for importers
 825 *
 826 * 1. Importers must hold the dma-buf reservation lock when calling these
 827 *    functions:
 828 *
 829 *     - dma_buf_pin()
 830 *     - dma_buf_unpin()
 831 *     - dma_buf_map_attachment()
 832 *     - dma_buf_unmap_attachment()
 833 *     - dma_buf_vmap()
 834 *     - dma_buf_vunmap()
 835 *
 836 * 2. Importers must not hold the dma-buf reservation lock when calling these
 837 *    functions:
 838 *
 839 *     - dma_buf_attach()
 840 *     - dma_buf_dynamic_attach()
 841 *     - dma_buf_detach()
 842 *     - dma_buf_export()
 843 *     - dma_buf_fd()
 844 *     - dma_buf_get()
 845 *     - dma_buf_put()
 846 *     - dma_buf_mmap()
 847 *     - dma_buf_begin_cpu_access()
 848 *     - dma_buf_end_cpu_access()
 849 *     - dma_buf_map_attachment_unlocked()
 850 *     - dma_buf_unmap_attachment_unlocked()
 851 *     - dma_buf_vmap_unlocked()
 852 *     - dma_buf_vunmap_unlocked()
 853 *
 854 * Convention for exporters
 855 *
 856 * 1. These &dma_buf_ops callbacks are invoked with unlocked dma-buf
 857 *    reservation and exporter can take the lock:
 858 *
 859 *     - &dma_buf_ops.attach()
 860 *     - &dma_buf_ops.detach()
 861 *     - &dma_buf_ops.release()
 862 *     - &dma_buf_ops.begin_cpu_access()
 863 *     - &dma_buf_ops.end_cpu_access()
 864 *     - &dma_buf_ops.mmap()
 865 *
 866 * 2. These &dma_buf_ops callbacks are invoked with locked dma-buf
 867 *    reservation and exporter can't take the lock:
 868 *
 869 *     - &dma_buf_ops.pin()
 870 *     - &dma_buf_ops.unpin()
 871 *     - &dma_buf_ops.map_dma_buf()
 872 *     - &dma_buf_ops.unmap_dma_buf()
 873 *     - &dma_buf_ops.vmap()
 874 *     - &dma_buf_ops.vunmap()
 875 *
 876 * 3. Exporters must hold the dma-buf reservation lock when calling these
 877 *    functions:
 878 *
 879 *     - dma_buf_move_notify()
 880 */
 881
 882/**
 883 * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list
 884 * @dmabuf:		[in]	buffer to attach device to.
 885 * @dev:		[in]	device to be attached.
 886 * @importer_ops:	[in]	importer operations for the attachment
 887 * @importer_priv:	[in]	importer private pointer for the attachment
 888 *
 889 * Returns struct dma_buf_attachment pointer for this attachment. Attachments
 890 * must be cleaned up by calling dma_buf_detach().
 891 *
 892 * Optionally this calls &dma_buf_ops.attach to allow device-specific attach
 893 * functionality.
 894 *
 895 * Returns:
 896 *
 897 * A pointer to newly created &dma_buf_attachment on success, or a negative
 898 * error code wrapped into a pointer on failure.
 899 *
 900 * Note that this can fail if the backing storage of @dmabuf is in a place not
 901 * accessible to @dev, and cannot be moved to a more suitable place. This is
 902 * indicated with the error code -EBUSY.
 903 */
 904struct dma_buf_attachment *
 905dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,
 906		       const struct dma_buf_attach_ops *importer_ops,
 907		       void *importer_priv)
 908{
 909	struct dma_buf_attachment *attach;
 910	int ret;
 911
 912	if (WARN_ON(!dmabuf || !dev))
 913		return ERR_PTR(-EINVAL);
 914
 915	if (WARN_ON(importer_ops && !importer_ops->move_notify))
 916		return ERR_PTR(-EINVAL);
 917
 918	attach = kzalloc(sizeof(*attach), GFP_KERNEL);
 919	if (!attach)
 920		return ERR_PTR(-ENOMEM);
 921
 922	attach->dev = dev;
 923	attach->dmabuf = dmabuf;
 924	if (importer_ops)
 925		attach->peer2peer = importer_ops->allow_peer2peer;
 926	attach->importer_ops = importer_ops;
 927	attach->importer_priv = importer_priv;
 928
 929	if (dmabuf->ops->attach) {
 930		ret = dmabuf->ops->attach(dmabuf, attach);
 931		if (ret)
 932			goto err_attach;
 933	}
 934	dma_resv_lock(dmabuf->resv, NULL);
 935	list_add(&attach->node, &dmabuf->attachments);
 936	dma_resv_unlock(dmabuf->resv);
 937
 938	/* When either the importer or the exporter can't handle dynamic
 939	 * mappings we cache the mapping here to avoid issues with the
 940	 * reservation object lock.
 941	 */
 942	if (dma_buf_attachment_is_dynamic(attach) !=
 943	    dma_buf_is_dynamic(dmabuf)) {
 944		struct sg_table *sgt;
 945
 946		dma_resv_lock(attach->dmabuf->resv, NULL);
 947		if (dma_buf_is_dynamic(attach->dmabuf)) {
 948			ret = dmabuf->ops->pin(attach);
 949			if (ret)
 950				goto err_unlock;
 951		}
 952
 953		sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);
 954		if (!sgt)
 955			sgt = ERR_PTR(-ENOMEM);
 956		if (IS_ERR(sgt)) {
 957			ret = PTR_ERR(sgt);
 958			goto err_unpin;
 959		}
 960		dma_resv_unlock(attach->dmabuf->resv);
 961		attach->sgt = sgt;
 962		attach->dir = DMA_BIDIRECTIONAL;
 963	}
 964
 
 965	return attach;
 966
 967err_attach:
 968	kfree(attach);
 
 969	return ERR_PTR(ret);
 970
 971err_unpin:
 972	if (dma_buf_is_dynamic(attach->dmabuf))
 973		dmabuf->ops->unpin(attach);
 974
 975err_unlock:
 976	dma_resv_unlock(attach->dmabuf->resv);
 977
 978	dma_buf_detach(dmabuf, attach);
 979	return ERR_PTR(ret);
 980}
 981EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, "DMA_BUF");
 982
 983/**
 984 * dma_buf_attach - Wrapper for dma_buf_dynamic_attach
 985 * @dmabuf:	[in]	buffer to attach device to.
 986 * @dev:	[in]	device to be attached.
 987 *
 988 * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static
 989 * mapping.
 990 */
 991struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,
 992					  struct device *dev)
 993{
 994	return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);
 995}
 996EXPORT_SYMBOL_NS_GPL(dma_buf_attach, "DMA_BUF");
 997
 998static void __unmap_dma_buf(struct dma_buf_attachment *attach,
 999			    struct sg_table *sg_table,
1000			    enum dma_data_direction direction)
1001{
1002	/* uses XOR, hence this unmangles */
1003	mangle_sg_table(sg_table);
1004
1005	attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);
1006}
 
1007
1008/**
1009 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list
 
1010 * @dmabuf:	[in]	buffer to detach from.
1011 * @attach:	[in]	attachment to be detached; is free'd after this call.
1012 *
1013 * Clean up a device attachment obtained by calling dma_buf_attach().
1014 *
1015 * Optionally this calls &dma_buf_ops.detach for device-specific detach.
1016 */
1017void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)
1018{
1019	if (WARN_ON(!dmabuf || !attach || dmabuf != attach->dmabuf))
1020		return;
1021
1022	dma_resv_lock(dmabuf->resv, NULL);
1023
1024	if (attach->sgt) {
1025
1026		__unmap_dma_buf(attach, attach->sgt, attach->dir);
1027
1028		if (dma_buf_is_dynamic(attach->dmabuf))
1029			dmabuf->ops->unpin(attach);
1030	}
1031	list_del(&attach->node);
1032
1033	dma_resv_unlock(dmabuf->resv);
1034
1035	if (dmabuf->ops->detach)
1036		dmabuf->ops->detach(dmabuf, attach);
1037
 
1038	kfree(attach);
1039}
1040EXPORT_SYMBOL_NS_GPL(dma_buf_detach, "DMA_BUF");
1041
1042/**
1043 * dma_buf_pin - Lock down the DMA-buf
1044 * @attach:	[in]	attachment which should be pinned
1045 *
1046 * Only dynamic importers (who set up @attach with dma_buf_dynamic_attach()) may
1047 * call this, and only for limited use cases like scanout and not for temporary
1048 * pin operations. It is not permitted to allow userspace to pin arbitrary
1049 * amounts of buffers through this interface.
1050 *
1051 * Buffers must be unpinned by calling dma_buf_unpin().
1052 *
1053 * Returns:
1054 * 0 on success, negative error code on failure.
1055 */
1056int dma_buf_pin(struct dma_buf_attachment *attach)
1057{
1058	struct dma_buf *dmabuf = attach->dmabuf;
1059	int ret = 0;
1060
1061	WARN_ON(!dma_buf_attachment_is_dynamic(attach));
1062
1063	dma_resv_assert_held(dmabuf->resv);
1064
1065	if (dmabuf->ops->pin)
1066		ret = dmabuf->ops->pin(attach);
1067
1068	return ret;
1069}
1070EXPORT_SYMBOL_NS_GPL(dma_buf_pin, "DMA_BUF");
1071
1072/**
1073 * dma_buf_unpin - Unpin a DMA-buf
1074 * @attach:	[in]	attachment which should be unpinned
1075 *
1076 * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move
1077 * any mapping of @attach again and inform the importer through
1078 * &dma_buf_attach_ops.move_notify.
1079 */
1080void dma_buf_unpin(struct dma_buf_attachment *attach)
1081{
1082	struct dma_buf *dmabuf = attach->dmabuf;
1083
1084	WARN_ON(!dma_buf_attachment_is_dynamic(attach));
1085
1086	dma_resv_assert_held(dmabuf->resv);
1087
1088	if (dmabuf->ops->unpin)
1089		dmabuf->ops->unpin(attach);
1090}
1091EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, "DMA_BUF");
1092
1093/**
1094 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;
1095 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
1096 * dma_buf_ops.
1097 * @attach:	[in]	attachment whose scatterlist is to be returned
1098 * @direction:	[in]	direction of DMA transfer
1099 *
1100 * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR
1101 * on error. May return -EINTR if it is interrupted by a signal.
1102 *
1103 * On success, the DMA addresses and lengths in the returned scatterlist are
1104 * PAGE_SIZE aligned.
1105 *
1106 * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that
1107 * the underlying backing storage is pinned for as long as a mapping exists,
1108 * therefore users/importers should not hold onto a mapping for undue amounts of
1109 * time.
1110 *
1111 * Important: Dynamic importers must wait for the exclusive fence of the struct
1112 * dma_resv attached to the DMA-BUF first.
1113 */
1114struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,
1115					enum dma_data_direction direction)
1116{
1117	struct sg_table *sg_table;
1118	int r;
1119
1120	might_sleep();
1121
1122	if (WARN_ON(!attach || !attach->dmabuf))
1123		return ERR_PTR(-EINVAL);
1124
1125	dma_resv_assert_held(attach->dmabuf->resv);
1126
1127	if (attach->sgt) {
1128		/*
1129		 * Two mappings with different directions for the same
1130		 * attachment are not allowed.
1131		 */
1132		if (attach->dir != direction &&
1133		    attach->dir != DMA_BIDIRECTIONAL)
1134			return ERR_PTR(-EBUSY);
1135
1136		return attach->sgt;
1137	}
1138
1139	if (dma_buf_is_dynamic(attach->dmabuf)) {
1140		if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {
1141			r = attach->dmabuf->ops->pin(attach);
1142			if (r)
1143				return ERR_PTR(r);
1144		}
1145	}
1146
1147	sg_table = __map_dma_buf(attach, direction);
1148	if (!sg_table)
1149		sg_table = ERR_PTR(-ENOMEM);
1150
1151	if (IS_ERR(sg_table) && dma_buf_is_dynamic(attach->dmabuf) &&
1152	     !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
1153		attach->dmabuf->ops->unpin(attach);
1154
1155	if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {
1156		attach->sgt = sg_table;
1157		attach->dir = direction;
1158	}
1159
1160#ifdef CONFIG_DMA_API_DEBUG
1161	if (!IS_ERR(sg_table)) {
1162		struct scatterlist *sg;
1163		u64 addr;
1164		int len;
1165		int i;
1166
1167		for_each_sgtable_dma_sg(sg_table, sg, i) {
1168			addr = sg_dma_address(sg);
1169			len = sg_dma_len(sg);
1170			if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) {
1171				pr_debug("%s: addr %llx or len %x is not page aligned!\n",
1172					 __func__, addr, len);
1173			}
1174		}
1175	}
1176#endif /* CONFIG_DMA_API_DEBUG */
1177	return sg_table;
1178}
1179EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment, "DMA_BUF");
1180
1181/**
1182 * dma_buf_map_attachment_unlocked - Returns the scatterlist table of the attachment;
1183 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the
1184 * dma_buf_ops.
1185 * @attach:	[in]	attachment whose scatterlist is to be returned
1186 * @direction:	[in]	direction of DMA transfer
1187 *
1188 * Unlocked variant of dma_buf_map_attachment().
1189 */
1190struct sg_table *
1191dma_buf_map_attachment_unlocked(struct dma_buf_attachment *attach,
1192				enum dma_data_direction direction)
1193{
1194	struct sg_table *sg_table;
1195
1196	might_sleep();
1197
1198	if (WARN_ON(!attach || !attach->dmabuf))
1199		return ERR_PTR(-EINVAL);
1200
1201	dma_resv_lock(attach->dmabuf->resv, NULL);
1202	sg_table = dma_buf_map_attachment(attach, direction);
1203	dma_resv_unlock(attach->dmabuf->resv);
1204
1205	return sg_table;
1206}
1207EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment_unlocked, "DMA_BUF");
1208
1209/**
1210 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might
1211 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
1212 * dma_buf_ops.
1213 * @attach:	[in]	attachment to unmap buffer from
1214 * @sg_table:	[in]	scatterlist info of the buffer to unmap
1215 * @direction:  [in]    direction of DMA transfer
1216 *
1217 * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().
1218 */
1219void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,
1220				struct sg_table *sg_table,
1221				enum dma_data_direction direction)
1222{
1223	might_sleep();
1224
1225	if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
1226		return;
1227
1228	dma_resv_assert_held(attach->dmabuf->resv);
1229
1230	if (attach->sgt == sg_table)
1231		return;
1232
1233	__unmap_dma_buf(attach, sg_table, direction);
1234
1235	if (dma_buf_is_dynamic(attach->dmabuf) &&
1236	    !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))
1237		dma_buf_unpin(attach);
1238}
1239EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment, "DMA_BUF");
1240
1241/**
1242 * dma_buf_unmap_attachment_unlocked - unmaps and decreases usecount of the buffer;might
1243 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of
1244 * dma_buf_ops.
1245 * @attach:	[in]	attachment to unmap buffer from
1246 * @sg_table:	[in]	scatterlist info of the buffer to unmap
1247 * @direction:	[in]	direction of DMA transfer
1248 *
1249 * Unlocked variant of dma_buf_unmap_attachment().
1250 */
1251void dma_buf_unmap_attachment_unlocked(struct dma_buf_attachment *attach,
1252				       struct sg_table *sg_table,
1253				       enum dma_data_direction direction)
1254{
1255	might_sleep();
1256
1257	if (WARN_ON(!attach || !attach->dmabuf || !sg_table))
1258		return;
1259
1260	dma_resv_lock(attach->dmabuf->resv, NULL);
1261	dma_buf_unmap_attachment(attach, sg_table, direction);
1262	dma_resv_unlock(attach->dmabuf->resv);
1263}
1264EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment_unlocked, "DMA_BUF");
1265
1266/**
1267 * dma_buf_move_notify - notify attachments that DMA-buf is moving
1268 *
1269 * @dmabuf:	[in]	buffer which is moving
1270 *
1271 * Informs all attachments that they need to destroy and recreate all their
1272 * mappings.
1273 */
1274void dma_buf_move_notify(struct dma_buf *dmabuf)
1275{
1276	struct dma_buf_attachment *attach;
1277
1278	dma_resv_assert_held(dmabuf->resv);
1279
1280	list_for_each_entry(attach, &dmabuf->attachments, node)
1281		if (attach->importer_ops)
1282			attach->importer_ops->move_notify(attach);
1283}
1284EXPORT_SYMBOL_NS_GPL(dma_buf_move_notify, "DMA_BUF");
1285
1286/**
1287 * DOC: cpu access
1288 *
1289 * There are multiple reasons for supporting CPU access to a dma buffer object:
1290 *
1291 * - Fallback operations in the kernel, for example when a device is connected
1292 *   over USB and the kernel needs to shuffle the data around first before
1293 *   sending it away. Cache coherency is handled by bracketing any transactions
1294 *   with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()
1295 *   access.
1296 *
1297 *   Since for most kernel internal dma-buf accesses need the entire buffer, a
1298 *   vmap interface is introduced. Note that on very old 32-bit architectures
1299 *   vmalloc space might be limited and result in vmap calls failing.
1300 *
1301 *   Interfaces:
1302 *
1303 *   .. code-block:: c
1304 *
1305 *     void *dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
1306 *     void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
1307 *
1308 *   The vmap call can fail if there is no vmap support in the exporter, or if
1309 *   it runs out of vmalloc space. Note that the dma-buf layer keeps a reference
1310 *   count for all vmap access and calls down into the exporter's vmap function
1311 *   only when no vmapping exists, and only unmaps it once. Protection against
1312 *   concurrent vmap/vunmap calls is provided by taking the &dma_buf.lock mutex.
1313 *
1314 * - For full compatibility on the importer side with existing userspace
1315 *   interfaces, which might already support mmap'ing buffers. This is needed in
1316 *   many processing pipelines (e.g. feeding a software rendered image into a
1317 *   hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION
1318 *   framework already supported this and for DMA buffer file descriptors to
1319 *   replace ION buffers mmap support was needed.
1320 *
1321 *   There is no special interfaces, userspace simply calls mmap on the dma-buf
1322 *   fd. But like for CPU access there's a need to bracket the actual access,
1323 *   which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that
1324 *   DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must
1325 *   be restarted.
1326 *
1327 *   Some systems might need some sort of cache coherency management e.g. when
1328 *   CPU and GPU domains are being accessed through dma-buf at the same time.
1329 *   To circumvent this problem there are begin/end coherency markers, that
1330 *   forward directly to existing dma-buf device drivers vfunc hooks. Userspace
1331 *   can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The
1332 *   sequence would be used like following:
1333 *
1334 *     - mmap dma-buf fd
1335 *     - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write
1336 *       to mmap area 3. SYNC_END ioctl. This can be repeated as often as you
1337 *       want (with the new data being consumed by say the GPU or the scanout
1338 *       device)
1339 *     - munmap once you don't need the buffer any more
1340 *
1341 *    For correctness and optimal performance, it is always required to use
1342 *    SYNC_START and SYNC_END before and after, respectively, when accessing the
1343 *    mapped address. Userspace cannot rely on coherent access, even when there
1344 *    are systems where it just works without calling these ioctls.
1345 *
1346 * - And as a CPU fallback in userspace processing pipelines.
1347 *
1348 *   Similar to the motivation for kernel cpu access it is again important that
1349 *   the userspace code of a given importing subsystem can use the same
1350 *   interfaces with a imported dma-buf buffer object as with a native buffer
1351 *   object. This is especially important for drm where the userspace part of
1352 *   contemporary OpenGL, X, and other drivers is huge, and reworking them to
1353 *   use a different way to mmap a buffer rather invasive.
1354 *
1355 *   The assumption in the current dma-buf interfaces is that redirecting the
1356 *   initial mmap is all that's needed. A survey of some of the existing
1357 *   subsystems shows that no driver seems to do any nefarious thing like
1358 *   syncing up with outstanding asynchronous processing on the device or
1359 *   allocating special resources at fault time. So hopefully this is good
1360 *   enough, since adding interfaces to intercept pagefaults and allow pte
1361 *   shootdowns would increase the complexity quite a bit.
1362 *
1363 *   Interface:
1364 *
1365 *   .. code-block:: c
1366 *
1367 *     int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, unsigned long);
1368 *
1369 *   If the importing subsystem simply provides a special-purpose mmap call to
1370 *   set up a mapping in userspace, calling do_mmap with &dma_buf.file will
1371 *   equally achieve that for a dma-buf object.
1372 */
1373
1374static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1375				      enum dma_data_direction direction)
1376{
1377	bool write = (direction == DMA_BIDIRECTIONAL ||
1378		      direction == DMA_TO_DEVICE);
1379	struct dma_resv *resv = dmabuf->resv;
1380	long ret;
1381
1382	/* Wait on any implicit rendering fences */
1383	ret = dma_resv_wait_timeout(resv, dma_resv_usage_rw(write),
1384				    true, MAX_SCHEDULE_TIMEOUT);
1385	if (ret < 0)
1386		return ret;
1387
1388	return 0;
1389}
1390
1391/**
1392 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the
1393 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific
1394 * preparations. Coherency is only guaranteed in the specified range for the
1395 * specified access direction.
1396 * @dmabuf:	[in]	buffer to prepare cpu access for.
1397 * @direction:	[in]	direction of access.
1398 *
1399 * After the cpu access is complete the caller should call
1400 * dma_buf_end_cpu_access(). Only when cpu access is bracketed by both calls is
1401 * it guaranteed to be coherent with other DMA access.
1402 *
1403 * This function will also wait for any DMA transactions tracked through
1404 * implicit synchronization in &dma_buf.resv. For DMA transactions with explicit
1405 * synchronization this function will only ensure cache coherency, callers must
1406 * ensure synchronization with such DMA transactions on their own.
1407 *
1408 * Can return negative error values, returns 0 on success.
1409 */
1410int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
1411			     enum dma_data_direction direction)
1412{
1413	int ret = 0;
1414
1415	if (WARN_ON(!dmabuf))
1416		return -EINVAL;
1417
1418	might_lock(&dmabuf->resv->lock.base);
1419
1420	if (dmabuf->ops->begin_cpu_access)
1421		ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);
1422
1423	/* Ensure that all fences are waited upon - but we first allow
1424	 * the native handler the chance to do so more efficiently if it
1425	 * chooses. A double invocation here will be reasonably cheap no-op.
1426	 */
1427	if (ret == 0)
1428		ret = __dma_buf_begin_cpu_access(dmabuf, direction);
1429
1430	return ret;
1431}
1432EXPORT_SYMBOL_NS_GPL(dma_buf_begin_cpu_access, "DMA_BUF");
1433
1434/**
1435 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the
1436 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific
1437 * actions. Coherency is only guaranteed in the specified range for the
1438 * specified access direction.
1439 * @dmabuf:	[in]	buffer to complete cpu access for.
1440 * @direction:	[in]	direction of access.
1441 *
1442 * This terminates CPU access started with dma_buf_begin_cpu_access().
1443 *
1444 * Can return negative error values, returns 0 on success.
1445 */
1446int dma_buf_end_cpu_access(struct dma_buf *dmabuf,
1447			   enum dma_data_direction direction)
1448{
1449	int ret = 0;
1450
1451	WARN_ON(!dmabuf);
1452
1453	might_lock(&dmabuf->resv->lock.base);
1454
1455	if (dmabuf->ops->end_cpu_access)
1456		ret = dmabuf->ops->end_cpu_access(dmabuf, direction);
1457
1458	return ret;
1459}
1460EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, "DMA_BUF");
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1461
1462
1463/**
1464 * dma_buf_mmap - Setup up a userspace mmap with the given vma
1465 * @dmabuf:	[in]	buffer that should back the vma
1466 * @vma:	[in]	vma for the mmap
1467 * @pgoff:	[in]	offset in pages where this mmap should start within the
1468 *			dma-buf buffer.
1469 *
1470 * This function adjusts the passed in vma so that it points at the file of the
1471 * dma_buf operation. It also adjusts the starting pgoff and does bounds
1472 * checking on the size of the vma. Then it calls the exporters mmap function to
1473 * set up the mapping.
1474 *
1475 * Can return negative error values, returns 0 on success.
1476 */
1477int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
1478		 unsigned long pgoff)
1479{
1480	if (WARN_ON(!dmabuf || !vma))
1481		return -EINVAL;
1482
1483	/* check if buffer supports mmap */
1484	if (!dmabuf->ops->mmap)
1485		return -EINVAL;
1486
1487	/* check for offset overflow */
1488	if (pgoff + vma_pages(vma) < pgoff)
1489		return -EOVERFLOW;
1490
1491	/* check for overflowing the buffer's size */
1492	if (pgoff + vma_pages(vma) >
1493	    dmabuf->size >> PAGE_SHIFT)
1494		return -EINVAL;
1495
1496	/* readjust the vma */
1497	vma_set_file(vma, dmabuf->file);
 
 
1498	vma->vm_pgoff = pgoff;
1499
1500	return dmabuf->ops->mmap(dmabuf, vma);
 
 
 
 
 
 
 
 
 
 
1501}
1502EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, "DMA_BUF");
1503
1504/**
1505 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel
1506 * address space. Same restrictions as for vmap and friends apply.
1507 * @dmabuf:	[in]	buffer to vmap
1508 * @map:	[out]	returns the vmap pointer
1509 *
1510 * This call may fail due to lack of virtual mapping address space.
1511 * These calls are optional in drivers. The intended use for them
1512 * is for mapping objects linear in kernel space for high use objects.
 
1513 *
1514 * To ensure coherency users must call dma_buf_begin_cpu_access() and
1515 * dma_buf_end_cpu_access() around any cpu access performed through this
1516 * mapping.
1517 *
1518 * Returns 0 on success, or a negative errno code otherwise.
1519 */
1520int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)
1521{
1522	struct iosys_map ptr;
1523	int ret;
1524
1525	iosys_map_clear(map);
1526
1527	if (WARN_ON(!dmabuf))
1528		return -EINVAL;
1529
1530	dma_resv_assert_held(dmabuf->resv);
1531
1532	if (!dmabuf->ops->vmap)
1533		return -EINVAL;
1534
 
1535	if (dmabuf->vmapping_counter) {
1536		dmabuf->vmapping_counter++;
1537		BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
1538		*map = dmabuf->vmap_ptr;
1539		return 0;
1540	}
1541
1542	BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));
1543
1544	ret = dmabuf->ops->vmap(dmabuf, &ptr);
1545	if (WARN_ON_ONCE(ret))
1546		return ret;
 
 
1547
1548	dmabuf->vmap_ptr = ptr;
1549	dmabuf->vmapping_counter = 1;
1550
1551	*map = dmabuf->vmap_ptr;
1552
1553	return 0;
1554}
1555EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, "DMA_BUF");
1556
1557/**
1558 * dma_buf_vmap_unlocked - Create virtual mapping for the buffer object into kernel
1559 * address space. Same restrictions as for vmap and friends apply.
1560 * @dmabuf:	[in]	buffer to vmap
1561 * @map:	[out]	returns the vmap pointer
1562 *
1563 * Unlocked version of dma_buf_vmap()
1564 *
1565 * Returns 0 on success, or a negative errno code otherwise.
1566 */
1567int dma_buf_vmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
1568{
1569	int ret;
1570
1571	iosys_map_clear(map);
1572
1573	if (WARN_ON(!dmabuf))
1574		return -EINVAL;
1575
1576	dma_resv_lock(dmabuf->resv, NULL);
1577	ret = dma_buf_vmap(dmabuf, map);
1578	dma_resv_unlock(dmabuf->resv);
1579
1580	return ret;
1581}
1582EXPORT_SYMBOL_NS_GPL(dma_buf_vmap_unlocked, "DMA_BUF");
1583
1584/**
1585 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.
1586 * @dmabuf:	[in]	buffer to vunmap
1587 * @map:	[in]	vmap pointer to vunmap
1588 */
1589void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)
1590{
1591	if (WARN_ON(!dmabuf))
1592		return;
1593
1594	dma_resv_assert_held(dmabuf->resv);
1595
1596	BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));
1597	BUG_ON(dmabuf->vmapping_counter == 0);
1598	BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));
1599
 
1600	if (--dmabuf->vmapping_counter == 0) {
1601		if (dmabuf->ops->vunmap)
1602			dmabuf->ops->vunmap(dmabuf, map);
1603		iosys_map_clear(&dmabuf->vmap_ptr);
1604	}
 
1605}
1606EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, "DMA_BUF");
1607
1608/**
1609 * dma_buf_vunmap_unlocked - Unmap a vmap obtained by dma_buf_vmap.
1610 * @dmabuf:	[in]	buffer to vunmap
1611 * @map:	[in]	vmap pointer to vunmap
1612 */
1613void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)
1614{
1615	if (WARN_ON(!dmabuf))
1616		return;
1617
1618	dma_resv_lock(dmabuf->resv, NULL);
1619	dma_buf_vunmap(dmabuf, map);
1620	dma_resv_unlock(dmabuf->resv);
1621}
1622EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap_unlocked, "DMA_BUF");
1623
1624#ifdef CONFIG_DEBUG_FS
1625static int dma_buf_debug_show(struct seq_file *s, void *unused)
1626{
 
1627	struct dma_buf *buf_obj;
1628	struct dma_buf_attachment *attach_obj;
1629	int count = 0, attach_count;
1630	size_t size = 0;
1631	int ret;
1632
1633	ret = mutex_lock_interruptible(&debugfs_list_mutex);
1634
1635	if (ret)
1636		return ret;
1637
1638	seq_puts(s, "\nDma-buf Objects:\n");
1639	seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\tname\n",
1640		   "size", "flags", "mode", "count", "ino");
1641
1642	list_for_each_entry(buf_obj, &debugfs_list, list_node) {
1643
1644		ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);
1645		if (ret)
1646			goto error_unlock;
1647
 
 
 
 
 
1648
1649		spin_lock(&buf_obj->name_lock);
1650		seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",
1651				buf_obj->size,
1652				buf_obj->file->f_flags, buf_obj->file->f_mode,
1653				file_count(buf_obj->file),
1654				buf_obj->exp_name,
1655				file_inode(buf_obj->file)->i_ino,
1656				buf_obj->name ?: "<none>");
1657		spin_unlock(&buf_obj->name_lock);
1658
1659		dma_resv_describe(buf_obj->resv, s);
1660
1661		seq_puts(s, "\tAttached Devices:\n");
1662		attach_count = 0;
1663
1664		list_for_each_entry(attach_obj, &buf_obj->attachments, node) {
1665			seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));
 
 
1666			attach_count++;
1667		}
1668		dma_resv_unlock(buf_obj->resv);
1669
1670		seq_printf(s, "Total %d devices attached\n\n",
1671				attach_count);
1672
1673		count++;
1674		size += buf_obj->size;
 
1675	}
1676
1677	seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);
1678
1679	mutex_unlock(&debugfs_list_mutex);
1680	return 0;
 
1681
1682error_unlock:
1683	mutex_unlock(&debugfs_list_mutex);
1684	return ret;
 
 
 
1685}
1686
1687DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);
 
 
 
 
 
 
 
 
 
 
1688
1689static struct dentry *dma_buf_debugfs_dir;
1690
1691static int dma_buf_init_debugfs(void)
1692{
1693	struct dentry *d;
1694	int err = 0;
1695
1696	d = debugfs_create_dir("dma_buf", NULL);
1697	if (IS_ERR(d))
1698		return PTR_ERR(d);
1699
1700	dma_buf_debugfs_dir = d;
1701
1702	d = debugfs_create_file("bufinfo", 0444, dma_buf_debugfs_dir,
1703				NULL, &dma_buf_debug_fops);
1704	if (IS_ERR(d)) {
1705		pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");
1706		debugfs_remove_recursive(dma_buf_debugfs_dir);
1707		dma_buf_debugfs_dir = NULL;
1708		err = PTR_ERR(d);
1709	}
1710
 
 
 
 
 
1711	return err;
1712}
1713
1714static void dma_buf_uninit_debugfs(void)
1715{
1716	debugfs_remove_recursive(dma_buf_debugfs_dir);
 
 
 
 
 
 
 
 
 
 
 
 
1717}
1718#else
1719static inline int dma_buf_init_debugfs(void)
1720{
1721	return 0;
1722}
1723static inline void dma_buf_uninit_debugfs(void)
1724{
1725}
1726#endif
1727
1728static int __init dma_buf_init(void)
1729{
1730	int ret;
1731
1732	ret = dma_buf_init_sysfs_statistics();
1733	if (ret)
1734		return ret;
1735
1736	dma_buf_mnt = kern_mount(&dma_buf_fs_type);
1737	if (IS_ERR(dma_buf_mnt))
1738		return PTR_ERR(dma_buf_mnt);
1739
1740	dma_buf_init_debugfs();
1741	return 0;
1742}
1743subsys_initcall(dma_buf_init);
1744
1745static void __exit dma_buf_deinit(void)
1746{
1747	dma_buf_uninit_debugfs();
1748	kern_unmount(dma_buf_mnt);
1749	dma_buf_uninit_sysfs_statistics();
1750}
1751__exitcall(dma_buf_deinit);