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1// SPDX-License-Identifier: GPL-2.0-only2/*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 specially9 * Arnd Bergmann <arnd@arndb.de>, Rob Clark <rob@ti.com> and10 * Daniel Vetter <daniel@ffwll.ch> for their support in creation and11 * 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#else59static void __dma_buf_debugfs_list_add(struct dma_buf *dmabuf)60{61}62 63static void __dma_buf_debugfs_list_del(struct file *file)64{65}66#endif67 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 else97 * * dmabuf->cb_in/out.active are non-0 despite no pending fence callback98 */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 idiomatic180 SEEK_END(0), SEEK_CUR(0) pattern */181 if (whence == SEEK_END)182 base = dmabuf->size;183 else if (whence == SEEK_SET)184 base = 0;185 else186 return -EINVAL;187 188 if (offset != 0)189 return -EINVAL;190 191 return base + offset;192}193 194/**195 * DOC: implicit fence polling196 *197 * To support cross-device and cross-driver synchronization of buffer access198 * implicit fences (represented internally in the kernel with &struct dma_fence)199 * can be attached to a &dma_buf. The glue for that and a few related things are200 * provided in the &dma_resv structure.201 *202 * Userspace can query the state of these implicitly tracked fences using poll()203 * and related system calls:204 *205 * - Checking for EPOLLIN, i.e. read access, can be use to query the state of the206 * most recent write or exclusive fence.207 *208 * - Checking for EPOLLOUT, i.e. write access, can be used to query the state of209 * all attached fences, shared and exclusive ones.210 *211 * Note that this only signals the completion of the respective fences, i.e. the212 * DMA transfers are complete. Cache flushing and any other necessary213 * preparations before CPU access can begin still need to happen.214 *215 * As an alternative to poll(), the set of fences on DMA buffer can be216 * exported as a &sync_file using &dma_buf_sync_file_export.217 */218 219static void dma_buf_poll_cb(struct dma_fence *fence, struct dma_fence_cb *cb)220{221 struct dma_buf_poll_cb_t *dcb = (struct dma_buf_poll_cb_t *)cb;222 struct dma_buf *dmabuf = container_of(dcb->poll, struct dma_buf, poll);223 unsigned long flags;224 225 spin_lock_irqsave(&dcb->poll->lock, flags);226 wake_up_locked_poll(dcb->poll, dcb->active);227 dcb->active = 0;228 spin_unlock_irqrestore(&dcb->poll->lock, flags);229 dma_fence_put(fence);230 /* Paired with get_file in dma_buf_poll */231 fput(dmabuf->file);232}233 234static bool dma_buf_poll_add_cb(struct dma_resv *resv, bool write,235 struct dma_buf_poll_cb_t *dcb)236{237 struct dma_resv_iter cursor;238 struct dma_fence *fence;239 int r;240 241 dma_resv_for_each_fence(&cursor, resv, dma_resv_usage_rw(write),242 fence) {243 dma_fence_get(fence);244 r = dma_fence_add_callback(fence, &dcb->cb, dma_buf_poll_cb);245 if (!r)246 return true;247 dma_fence_put(fence);248 }249 250 return false;251}252 253static __poll_t dma_buf_poll(struct file *file, poll_table *poll)254{255 struct dma_buf *dmabuf;256 struct dma_resv *resv;257 __poll_t events;258 259 dmabuf = file->private_data;260 if (!dmabuf || !dmabuf->resv)261 return EPOLLERR;262 263 resv = dmabuf->resv;264 265 poll_wait(file, &dmabuf->poll, poll);266 267 events = poll_requested_events(poll) & (EPOLLIN | EPOLLOUT);268 if (!events)269 return 0;270 271 dma_resv_lock(resv, NULL);272 273 if (events & EPOLLOUT) {274 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_out;275 276 /* Check that callback isn't busy */277 spin_lock_irq(&dmabuf->poll.lock);278 if (dcb->active)279 events &= ~EPOLLOUT;280 else281 dcb->active = EPOLLOUT;282 spin_unlock_irq(&dmabuf->poll.lock);283 284 if (events & EPOLLOUT) {285 /* Paired with fput in dma_buf_poll_cb */286 get_file(dmabuf->file);287 288 if (!dma_buf_poll_add_cb(resv, true, dcb))289 /* No callback queued, wake up any other waiters */290 dma_buf_poll_cb(NULL, &dcb->cb);291 else292 events &= ~EPOLLOUT;293 }294 }295 296 if (events & EPOLLIN) {297 struct dma_buf_poll_cb_t *dcb = &dmabuf->cb_in;298 299 /* Check that callback isn't busy */300 spin_lock_irq(&dmabuf->poll.lock);301 if (dcb->active)302 events &= ~EPOLLIN;303 else304 dcb->active = EPOLLIN;305 spin_unlock_irq(&dmabuf->poll.lock);306 307 if (events & EPOLLIN) {308 /* Paired with fput in dma_buf_poll_cb */309 get_file(dmabuf->file);310 311 if (!dma_buf_poll_add_cb(resv, false, dcb))312 /* No callback queued, wake up any other waiters */313 dma_buf_poll_cb(NULL, &dcb->cb);314 else315 events &= ~EPOLLIN;316 }317 }318 319 dma_resv_unlock(resv);320 return events;321}322 323/**324 * dma_buf_set_name - Set a name to a specific dma_buf to track the usage.325 * It could support changing the name of the dma-buf if the same326 * piece of memory is used for multiple purpose between different devices.327 *328 * @dmabuf: [in] dmabuf buffer that will be renamed.329 * @buf: [in] A piece of userspace memory that contains the name of330 * the dma-buf.331 *332 * Returns 0 on success. If the dma-buf buffer is already attached to333 * devices, return -EBUSY.334 *335 */336static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf)337{338 char *name = strndup_user(buf, DMA_BUF_NAME_LEN);339 340 if (IS_ERR(name))341 return PTR_ERR(name);342 343 spin_lock(&dmabuf->name_lock);344 kfree(dmabuf->name);345 dmabuf->name = name;346 spin_unlock(&dmabuf->name_lock);347 348 return 0;349}350 351#if IS_ENABLED(CONFIG_SYNC_FILE)352static long dma_buf_export_sync_file(struct dma_buf *dmabuf,353 void __user *user_data)354{355 struct dma_buf_export_sync_file arg;356 enum dma_resv_usage usage;357 struct dma_fence *fence = NULL;358 struct sync_file *sync_file;359 int fd, ret;360 361 if (copy_from_user(&arg, user_data, sizeof(arg)))362 return -EFAULT;363 364 if (arg.flags & ~DMA_BUF_SYNC_RW)365 return -EINVAL;366 367 if ((arg.flags & DMA_BUF_SYNC_RW) == 0)368 return -EINVAL;369 370 fd = get_unused_fd_flags(O_CLOEXEC);371 if (fd < 0)372 return fd;373 374 usage = dma_resv_usage_rw(arg.flags & DMA_BUF_SYNC_WRITE);375 ret = dma_resv_get_singleton(dmabuf->resv, usage, &fence);376 if (ret)377 goto err_put_fd;378 379 if (!fence)380 fence = dma_fence_get_stub();381 382 sync_file = sync_file_create(fence);383 384 dma_fence_put(fence);385 386 if (!sync_file) {387 ret = -ENOMEM;388 goto err_put_fd;389 }390 391 arg.fd = fd;392 if (copy_to_user(user_data, &arg, sizeof(arg))) {393 ret = -EFAULT;394 goto err_put_file;395 }396 397 fd_install(fd, sync_file->file);398 399 return 0;400 401err_put_file:402 fput(sync_file->file);403err_put_fd:404 put_unused_fd(fd);405 return ret;406}407 408static long dma_buf_import_sync_file(struct dma_buf *dmabuf,409 const void __user *user_data)410{411 struct dma_buf_import_sync_file arg;412 struct dma_fence *fence, *f;413 enum dma_resv_usage usage;414 struct dma_fence_unwrap iter;415 unsigned int num_fences;416 int ret = 0;417 418 if (copy_from_user(&arg, user_data, sizeof(arg)))419 return -EFAULT;420 421 if (arg.flags & ~DMA_BUF_SYNC_RW)422 return -EINVAL;423 424 if ((arg.flags & DMA_BUF_SYNC_RW) == 0)425 return -EINVAL;426 427 fence = sync_file_get_fence(arg.fd);428 if (!fence)429 return -EINVAL;430 431 usage = (arg.flags & DMA_BUF_SYNC_WRITE) ? DMA_RESV_USAGE_WRITE :432 DMA_RESV_USAGE_READ;433 434 num_fences = 0;435 dma_fence_unwrap_for_each(f, &iter, fence)436 ++num_fences;437 438 if (num_fences > 0) {439 dma_resv_lock(dmabuf->resv, NULL);440 441 ret = dma_resv_reserve_fences(dmabuf->resv, num_fences);442 if (!ret) {443 dma_fence_unwrap_for_each(f, &iter, fence)444 dma_resv_add_fence(dmabuf->resv, f, usage);445 }446 447 dma_resv_unlock(dmabuf->resv);448 }449 450 dma_fence_put(fence);451 452 return ret;453}454#endif455 456static long dma_buf_ioctl(struct file *file,457 unsigned int cmd, unsigned long arg)458{459 struct dma_buf *dmabuf;460 struct dma_buf_sync sync;461 enum dma_data_direction direction;462 int ret;463 464 dmabuf = file->private_data;465 466 switch (cmd) {467 case DMA_BUF_IOCTL_SYNC:468 if (copy_from_user(&sync, (void __user *) arg, sizeof(sync)))469 return -EFAULT;470 471 if (sync.flags & ~DMA_BUF_SYNC_VALID_FLAGS_MASK)472 return -EINVAL;473 474 switch (sync.flags & DMA_BUF_SYNC_RW) {475 case DMA_BUF_SYNC_READ:476 direction = DMA_FROM_DEVICE;477 break;478 case DMA_BUF_SYNC_WRITE:479 direction = DMA_TO_DEVICE;480 break;481 case DMA_BUF_SYNC_RW:482 direction = DMA_BIDIRECTIONAL;483 break;484 default:485 return -EINVAL;486 }487 488 if (sync.flags & DMA_BUF_SYNC_END)489 ret = dma_buf_end_cpu_access(dmabuf, direction);490 else491 ret = dma_buf_begin_cpu_access(dmabuf, direction);492 493 return ret;494 495 case DMA_BUF_SET_NAME_A:496 case DMA_BUF_SET_NAME_B:497 return dma_buf_set_name(dmabuf, (const char __user *)arg);498 499#if IS_ENABLED(CONFIG_SYNC_FILE)500 case DMA_BUF_IOCTL_EXPORT_SYNC_FILE:501 return dma_buf_export_sync_file(dmabuf, (void __user *)arg);502 case DMA_BUF_IOCTL_IMPORT_SYNC_FILE:503 return dma_buf_import_sync_file(dmabuf, (const void __user *)arg);504#endif505 506 default:507 return -ENOTTY;508 }509}510 511static void dma_buf_show_fdinfo(struct seq_file *m, struct file *file)512{513 struct dma_buf *dmabuf = file->private_data;514 515 seq_printf(m, "size:\t%zu\n", dmabuf->size);516 /* Don't count the temporary reference taken inside procfs seq_show */517 seq_printf(m, "count:\t%ld\n", file_count(dmabuf->file) - 1);518 seq_printf(m, "exp_name:\t%s\n", dmabuf->exp_name);519 spin_lock(&dmabuf->name_lock);520 if (dmabuf->name)521 seq_printf(m, "name:\t%s\n", dmabuf->name);522 spin_unlock(&dmabuf->name_lock);523}524 525static const struct file_operations dma_buf_fops = {526 .release = dma_buf_file_release,527 .mmap = dma_buf_mmap_internal,528 .llseek = dma_buf_llseek,529 .poll = dma_buf_poll,530 .unlocked_ioctl = dma_buf_ioctl,531 .compat_ioctl = compat_ptr_ioctl,532 .show_fdinfo = dma_buf_show_fdinfo,533};534 535/*536 * is_dma_buf_file - Check if struct file* is associated with dma_buf537 */538static inline int is_dma_buf_file(struct file *file)539{540 return file->f_op == &dma_buf_fops;541}542 543static struct file *dma_buf_getfile(size_t size, int flags)544{545 static atomic64_t dmabuf_inode = ATOMIC64_INIT(0);546 struct inode *inode = alloc_anon_inode(dma_buf_mnt->mnt_sb);547 struct file *file;548 549 if (IS_ERR(inode))550 return ERR_CAST(inode);551 552 inode->i_size = size;553 inode_set_bytes(inode, size);554 555 /*556 * The ->i_ino acquired from get_next_ino() is not unique thus557 * not suitable for using it as dentry name by dmabuf stats.558 * Override ->i_ino with the unique and dmabuffs specific559 * value.560 */561 inode->i_ino = atomic64_add_return(1, &dmabuf_inode);562 flags &= O_ACCMODE | O_NONBLOCK;563 file = alloc_file_pseudo(inode, dma_buf_mnt, "dmabuf",564 flags, &dma_buf_fops);565 if (IS_ERR(file))566 goto err_alloc_file;567 568 return file;569 570err_alloc_file:571 iput(inode);572 return file;573}574 575/**576 * DOC: dma buf device access577 *578 * For device DMA access to a shared DMA buffer the usual sequence of operations579 * is fairly simple:580 *581 * 1. The exporter defines his exporter instance using582 * DEFINE_DMA_BUF_EXPORT_INFO() and calls dma_buf_export() to wrap a private583 * buffer object into a &dma_buf. It then exports that &dma_buf to userspace584 * as a file descriptor by calling dma_buf_fd().585 *586 * 2. Userspace passes this file-descriptors to all drivers it wants this buffer587 * to share with: First the file descriptor is converted to a &dma_buf using588 * dma_buf_get(). Then the buffer is attached to the device using589 * dma_buf_attach().590 *591 * Up to this stage the exporter is still free to migrate or reallocate the592 * backing storage.593 *594 * 3. Once the buffer is attached to all devices userspace can initiate DMA595 * access to the shared buffer. In the kernel this is done by calling596 * dma_buf_map_attachment() and dma_buf_unmap_attachment().597 *598 * 4. Once a driver is done with a shared buffer it needs to call599 * dma_buf_detach() (after cleaning up any mappings) and then release the600 * reference acquired with dma_buf_get() by calling dma_buf_put().601 *602 * For the detailed semantics exporters are expected to implement see603 * &dma_buf_ops.604 */605 606/**607 * dma_buf_export - Creates a new dma_buf, and associates an anon file608 * with this buffer, so it can be exported.609 * Also connect the allocator specific data and ops to the buffer.610 * Additionally, provide a name string for exporter; useful in debugging.611 *612 * @exp_info: [in] holds all the export related information provided613 * by the exporter. see &struct dma_buf_export_info614 * for further details.615 *616 * Returns, on success, a newly created struct dma_buf object, which wraps the617 * supplied private data and operations for struct dma_buf_ops. On either618 * missing ops, or error in allocating struct dma_buf, will return negative619 * error.620 *621 * For most cases the easiest way to create @exp_info is through the622 * %DEFINE_DMA_BUF_EXPORT_INFO macro.623 */624struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)625{626 struct dma_buf *dmabuf;627 struct dma_resv *resv = exp_info->resv;628 struct file *file;629 size_t alloc_size = sizeof(struct dma_buf);630 int ret;631 632 if (WARN_ON(!exp_info->priv || !exp_info->ops633 || !exp_info->ops->map_dma_buf634 || !exp_info->ops->unmap_dma_buf635 || !exp_info->ops->release))636 return ERR_PTR(-EINVAL);637 638 if (WARN_ON(exp_info->ops->cache_sgt_mapping &&639 (exp_info->ops->pin || exp_info->ops->unpin)))640 return ERR_PTR(-EINVAL);641 642 if (WARN_ON(!exp_info->ops->pin != !exp_info->ops->unpin))643 return ERR_PTR(-EINVAL);644 645 if (!try_module_get(exp_info->owner))646 return ERR_PTR(-ENOENT);647 648 file = dma_buf_getfile(exp_info->size, exp_info->flags);649 if (IS_ERR(file)) {650 ret = PTR_ERR(file);651 goto err_module;652 }653 654 if (!exp_info->resv)655 alloc_size += sizeof(struct dma_resv);656 else657 /* prevent &dma_buf[1] == dma_buf->resv */658 alloc_size += 1;659 dmabuf = kzalloc(alloc_size, GFP_KERNEL);660 if (!dmabuf) {661 ret = -ENOMEM;662 goto err_file;663 }664 665 dmabuf->priv = exp_info->priv;666 dmabuf->ops = exp_info->ops;667 dmabuf->size = exp_info->size;668 dmabuf->exp_name = exp_info->exp_name;669 dmabuf->owner = exp_info->owner;670 spin_lock_init(&dmabuf->name_lock);671 init_waitqueue_head(&dmabuf->poll);672 dmabuf->cb_in.poll = dmabuf->cb_out.poll = &dmabuf->poll;673 dmabuf->cb_in.active = dmabuf->cb_out.active = 0;674 INIT_LIST_HEAD(&dmabuf->attachments);675 676 if (!resv) {677 dmabuf->resv = (struct dma_resv *)&dmabuf[1];678 dma_resv_init(dmabuf->resv);679 } else {680 dmabuf->resv = resv;681 }682 683 ret = dma_buf_stats_setup(dmabuf, file);684 if (ret)685 goto err_dmabuf;686 687 file->private_data = dmabuf;688 file->f_path.dentry->d_fsdata = dmabuf;689 dmabuf->file = file;690 691 __dma_buf_debugfs_list_add(dmabuf);692 693 return dmabuf;694 695err_dmabuf:696 if (!resv)697 dma_resv_fini(dmabuf->resv);698 kfree(dmabuf);699err_file:700 fput(file);701err_module:702 module_put(exp_info->owner);703 return ERR_PTR(ret);704}705EXPORT_SYMBOL_NS_GPL(dma_buf_export, DMA_BUF);706 707/**708 * dma_buf_fd - returns a file descriptor for the given struct dma_buf709 * @dmabuf: [in] pointer to dma_buf for which fd is required.710 * @flags: [in] flags to give to fd711 *712 * On success, returns an associated 'fd'. Else, returns error.713 */714int dma_buf_fd(struct dma_buf *dmabuf, int flags)715{716 int fd;717 718 if (!dmabuf || !dmabuf->file)719 return -EINVAL;720 721 fd = get_unused_fd_flags(flags);722 if (fd < 0)723 return fd;724 725 fd_install(fd, dmabuf->file);726 727 return fd;728}729EXPORT_SYMBOL_NS_GPL(dma_buf_fd, DMA_BUF);730 731/**732 * dma_buf_get - returns the struct dma_buf related to an fd733 * @fd: [in] fd associated with the struct dma_buf to be returned734 *735 * On success, returns the struct dma_buf associated with an fd; uses736 * file's refcounting done by fget to increase refcount. returns ERR_PTR737 * otherwise.738 */739struct dma_buf *dma_buf_get(int fd)740{741 struct file *file;742 743 file = fget(fd);744 745 if (!file)746 return ERR_PTR(-EBADF);747 748 if (!is_dma_buf_file(file)) {749 fput(file);750 return ERR_PTR(-EINVAL);751 }752 753 return file->private_data;754}755EXPORT_SYMBOL_NS_GPL(dma_buf_get, DMA_BUF);756 757/**758 * dma_buf_put - decreases refcount of the buffer759 * @dmabuf: [in] buffer to reduce refcount of760 *761 * Uses file's refcounting done implicitly by fput().762 *763 * If, as a result of this call, the refcount becomes 0, the 'release' file764 * operation related to this fd is called. It calls &dma_buf_ops.release vfunc765 * in turn, and frees the memory allocated for dmabuf when exported.766 */767void dma_buf_put(struct dma_buf *dmabuf)768{769 if (WARN_ON(!dmabuf || !dmabuf->file))770 return;771 772 fput(dmabuf->file);773}774EXPORT_SYMBOL_NS_GPL(dma_buf_put, DMA_BUF);775 776static void mangle_sg_table(struct sg_table *sg_table)777{778#ifdef CONFIG_DMABUF_DEBUG779 int i;780 struct scatterlist *sg;781 782 /* To catch abuse of the underlying struct page by importers mix783 * up the bits, but take care to preserve the low SG_ bits to784 * not corrupt the sgt. The mixing is undone in __unmap_dma_buf785 * before passing the sgt back to the exporter. */786 for_each_sgtable_sg(sg_table, sg, i)787 sg->page_link ^= ~0xffUL;788#endif789 790}791static struct sg_table * __map_dma_buf(struct dma_buf_attachment *attach,792 enum dma_data_direction direction)793{794 struct sg_table *sg_table;795 signed long ret;796 797 sg_table = attach->dmabuf->ops->map_dma_buf(attach, direction);798 if (IS_ERR_OR_NULL(sg_table))799 return sg_table;800 801 if (!dma_buf_attachment_is_dynamic(attach)) {802 ret = dma_resv_wait_timeout(attach->dmabuf->resv,803 DMA_RESV_USAGE_KERNEL, true,804 MAX_SCHEDULE_TIMEOUT);805 if (ret < 0) {806 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table,807 direction);808 return ERR_PTR(ret);809 }810 }811 812 mangle_sg_table(sg_table);813 return sg_table;814}815 816/**817 * DOC: locking convention818 *819 * In order to avoid deadlock situations between dma-buf exports and importers,820 * all dma-buf API users must follow the common dma-buf locking convention.821 *822 * Convention for importers823 *824 * 1. Importers must hold the dma-buf reservation lock when calling these825 * functions:826 *827 * - dma_buf_pin()828 * - dma_buf_unpin()829 * - dma_buf_map_attachment()830 * - dma_buf_unmap_attachment()831 * - dma_buf_vmap()832 * - dma_buf_vunmap()833 *834 * 2. Importers must not hold the dma-buf reservation lock when calling these835 * functions:836 *837 * - dma_buf_attach()838 * - dma_buf_dynamic_attach()839 * - dma_buf_detach()840 * - dma_buf_export()841 * - dma_buf_fd()842 * - dma_buf_get()843 * - dma_buf_put()844 * - dma_buf_mmap()845 * - dma_buf_begin_cpu_access()846 * - dma_buf_end_cpu_access()847 * - dma_buf_map_attachment_unlocked()848 * - dma_buf_unmap_attachment_unlocked()849 * - dma_buf_vmap_unlocked()850 * - dma_buf_vunmap_unlocked()851 *852 * Convention for exporters853 *854 * 1. These &dma_buf_ops callbacks are invoked with unlocked dma-buf855 * reservation and exporter can take the lock:856 *857 * - &dma_buf_ops.attach()858 * - &dma_buf_ops.detach()859 * - &dma_buf_ops.release()860 * - &dma_buf_ops.begin_cpu_access()861 * - &dma_buf_ops.end_cpu_access()862 * - &dma_buf_ops.mmap()863 *864 * 2. These &dma_buf_ops callbacks are invoked with locked dma-buf865 * reservation and exporter can't take the lock:866 *867 * - &dma_buf_ops.pin()868 * - &dma_buf_ops.unpin()869 * - &dma_buf_ops.map_dma_buf()870 * - &dma_buf_ops.unmap_dma_buf()871 * - &dma_buf_ops.vmap()872 * - &dma_buf_ops.vunmap()873 *874 * 3. Exporters must hold the dma-buf reservation lock when calling these875 * functions:876 *877 * - dma_buf_move_notify()878 */879 880/**881 * dma_buf_dynamic_attach - Add the device to dma_buf's attachments list882 * @dmabuf: [in] buffer to attach device to.883 * @dev: [in] device to be attached.884 * @importer_ops: [in] importer operations for the attachment885 * @importer_priv: [in] importer private pointer for the attachment886 *887 * Returns struct dma_buf_attachment pointer for this attachment. Attachments888 * must be cleaned up by calling dma_buf_detach().889 *890 * Optionally this calls &dma_buf_ops.attach to allow device-specific attach891 * functionality.892 *893 * Returns:894 *895 * A pointer to newly created &dma_buf_attachment on success, or a negative896 * error code wrapped into a pointer on failure.897 *898 * Note that this can fail if the backing storage of @dmabuf is in a place not899 * accessible to @dev, and cannot be moved to a more suitable place. This is900 * indicated with the error code -EBUSY.901 */902struct dma_buf_attachment *903dma_buf_dynamic_attach(struct dma_buf *dmabuf, struct device *dev,904 const struct dma_buf_attach_ops *importer_ops,905 void *importer_priv)906{907 struct dma_buf_attachment *attach;908 int ret;909 910 if (WARN_ON(!dmabuf || !dev))911 return ERR_PTR(-EINVAL);912 913 if (WARN_ON(importer_ops && !importer_ops->move_notify))914 return ERR_PTR(-EINVAL);915 916 attach = kzalloc(sizeof(*attach), GFP_KERNEL);917 if (!attach)918 return ERR_PTR(-ENOMEM);919 920 attach->dev = dev;921 attach->dmabuf = dmabuf;922 if (importer_ops)923 attach->peer2peer = importer_ops->allow_peer2peer;924 attach->importer_ops = importer_ops;925 attach->importer_priv = importer_priv;926 927 if (dmabuf->ops->attach) {928 ret = dmabuf->ops->attach(dmabuf, attach);929 if (ret)930 goto err_attach;931 }932 dma_resv_lock(dmabuf->resv, NULL);933 list_add(&attach->node, &dmabuf->attachments);934 dma_resv_unlock(dmabuf->resv);935 936 /* When either the importer or the exporter can't handle dynamic937 * mappings we cache the mapping here to avoid issues with the938 * reservation object lock.939 */940 if (dma_buf_attachment_is_dynamic(attach) !=941 dma_buf_is_dynamic(dmabuf)) {942 struct sg_table *sgt;943 944 dma_resv_lock(attach->dmabuf->resv, NULL);945 if (dma_buf_is_dynamic(attach->dmabuf)) {946 ret = dmabuf->ops->pin(attach);947 if (ret)948 goto err_unlock;949 }950 951 sgt = __map_dma_buf(attach, DMA_BIDIRECTIONAL);952 if (!sgt)953 sgt = ERR_PTR(-ENOMEM);954 if (IS_ERR(sgt)) {955 ret = PTR_ERR(sgt);956 goto err_unpin;957 }958 dma_resv_unlock(attach->dmabuf->resv);959 attach->sgt = sgt;960 attach->dir = DMA_BIDIRECTIONAL;961 }962 963 return attach;964 965err_attach:966 kfree(attach);967 return ERR_PTR(ret);968 969err_unpin:970 if (dma_buf_is_dynamic(attach->dmabuf))971 dmabuf->ops->unpin(attach);972 973err_unlock:974 dma_resv_unlock(attach->dmabuf->resv);975 976 dma_buf_detach(dmabuf, attach);977 return ERR_PTR(ret);978}979EXPORT_SYMBOL_NS_GPL(dma_buf_dynamic_attach, DMA_BUF);980 981/**982 * dma_buf_attach - Wrapper for dma_buf_dynamic_attach983 * @dmabuf: [in] buffer to attach device to.984 * @dev: [in] device to be attached.985 *986 * Wrapper to call dma_buf_dynamic_attach() for drivers which still use a static987 * mapping.988 */989struct dma_buf_attachment *dma_buf_attach(struct dma_buf *dmabuf,990 struct device *dev)991{992 return dma_buf_dynamic_attach(dmabuf, dev, NULL, NULL);993}994EXPORT_SYMBOL_NS_GPL(dma_buf_attach, DMA_BUF);995 996static void __unmap_dma_buf(struct dma_buf_attachment *attach,997 struct sg_table *sg_table,998 enum dma_data_direction direction)999{1000 /* uses XOR, hence this unmangles */1001 mangle_sg_table(sg_table);1002 1003 attach->dmabuf->ops->unmap_dma_buf(attach, sg_table, direction);1004}1005 1006/**1007 * dma_buf_detach - Remove the given attachment from dmabuf's attachments list1008 * @dmabuf: [in] buffer to detach from.1009 * @attach: [in] attachment to be detached; is free'd after this call.1010 *1011 * Clean up a device attachment obtained by calling dma_buf_attach().1012 *1013 * Optionally this calls &dma_buf_ops.detach for device-specific detach.1014 */1015void dma_buf_detach(struct dma_buf *dmabuf, struct dma_buf_attachment *attach)1016{1017 if (WARN_ON(!dmabuf || !attach || dmabuf != attach->dmabuf))1018 return;1019 1020 dma_resv_lock(dmabuf->resv, NULL);1021 1022 if (attach->sgt) {1023 1024 __unmap_dma_buf(attach, attach->sgt, attach->dir);1025 1026 if (dma_buf_is_dynamic(attach->dmabuf))1027 dmabuf->ops->unpin(attach);1028 }1029 list_del(&attach->node);1030 1031 dma_resv_unlock(dmabuf->resv);1032 1033 if (dmabuf->ops->detach)1034 dmabuf->ops->detach(dmabuf, attach);1035 1036 kfree(attach);1037}1038EXPORT_SYMBOL_NS_GPL(dma_buf_detach, DMA_BUF);1039 1040/**1041 * dma_buf_pin - Lock down the DMA-buf1042 * @attach: [in] attachment which should be pinned1043 *1044 * Only dynamic importers (who set up @attach with dma_buf_dynamic_attach()) may1045 * call this, and only for limited use cases like scanout and not for temporary1046 * pin operations. It is not permitted to allow userspace to pin arbitrary1047 * amounts of buffers through this interface.1048 *1049 * Buffers must be unpinned by calling dma_buf_unpin().1050 *1051 * Returns:1052 * 0 on success, negative error code on failure.1053 */1054int dma_buf_pin(struct dma_buf_attachment *attach)1055{1056 struct dma_buf *dmabuf = attach->dmabuf;1057 int ret = 0;1058 1059 WARN_ON(!dma_buf_attachment_is_dynamic(attach));1060 1061 dma_resv_assert_held(dmabuf->resv);1062 1063 if (dmabuf->ops->pin)1064 ret = dmabuf->ops->pin(attach);1065 1066 return ret;1067}1068EXPORT_SYMBOL_NS_GPL(dma_buf_pin, DMA_BUF);1069 1070/**1071 * dma_buf_unpin - Unpin a DMA-buf1072 * @attach: [in] attachment which should be unpinned1073 *1074 * This unpins a buffer pinned by dma_buf_pin() and allows the exporter to move1075 * any mapping of @attach again and inform the importer through1076 * &dma_buf_attach_ops.move_notify.1077 */1078void dma_buf_unpin(struct dma_buf_attachment *attach)1079{1080 struct dma_buf *dmabuf = attach->dmabuf;1081 1082 WARN_ON(!dma_buf_attachment_is_dynamic(attach));1083 1084 dma_resv_assert_held(dmabuf->resv);1085 1086 if (dmabuf->ops->unpin)1087 dmabuf->ops->unpin(attach);1088}1089EXPORT_SYMBOL_NS_GPL(dma_buf_unpin, DMA_BUF);1090 1091/**1092 * dma_buf_map_attachment - Returns the scatterlist table of the attachment;1093 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the1094 * dma_buf_ops.1095 * @attach: [in] attachment whose scatterlist is to be returned1096 * @direction: [in] direction of DMA transfer1097 *1098 * Returns sg_table containing the scatterlist to be returned; returns ERR_PTR1099 * on error. May return -EINTR if it is interrupted by a signal.1100 *1101 * On success, the DMA addresses and lengths in the returned scatterlist are1102 * PAGE_SIZE aligned.1103 *1104 * A mapping must be unmapped by using dma_buf_unmap_attachment(). Note that1105 * the underlying backing storage is pinned for as long as a mapping exists,1106 * therefore users/importers should not hold onto a mapping for undue amounts of1107 * time.1108 *1109 * Important: Dynamic importers must wait for the exclusive fence of the struct1110 * dma_resv attached to the DMA-BUF first.1111 */1112struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *attach,1113 enum dma_data_direction direction)1114{1115 struct sg_table *sg_table;1116 int r;1117 1118 might_sleep();1119 1120 if (WARN_ON(!attach || !attach->dmabuf))1121 return ERR_PTR(-EINVAL);1122 1123 dma_resv_assert_held(attach->dmabuf->resv);1124 1125 if (attach->sgt) {1126 /*1127 * Two mappings with different directions for the same1128 * attachment are not allowed.1129 */1130 if (attach->dir != direction &&1131 attach->dir != DMA_BIDIRECTIONAL)1132 return ERR_PTR(-EBUSY);1133 1134 return attach->sgt;1135 }1136 1137 if (dma_buf_is_dynamic(attach->dmabuf)) {1138 if (!IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY)) {1139 r = attach->dmabuf->ops->pin(attach);1140 if (r)1141 return ERR_PTR(r);1142 }1143 }1144 1145 sg_table = __map_dma_buf(attach, direction);1146 if (!sg_table)1147 sg_table = ERR_PTR(-ENOMEM);1148 1149 if (IS_ERR(sg_table) && dma_buf_is_dynamic(attach->dmabuf) &&1150 !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))1151 attach->dmabuf->ops->unpin(attach);1152 1153 if (!IS_ERR(sg_table) && attach->dmabuf->ops->cache_sgt_mapping) {1154 attach->sgt = sg_table;1155 attach->dir = direction;1156 }1157 1158#ifdef CONFIG_DMA_API_DEBUG1159 if (!IS_ERR(sg_table)) {1160 struct scatterlist *sg;1161 u64 addr;1162 int len;1163 int i;1164 1165 for_each_sgtable_dma_sg(sg_table, sg, i) {1166 addr = sg_dma_address(sg);1167 len = sg_dma_len(sg);1168 if (!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(len)) {1169 pr_debug("%s: addr %llx or len %x is not page aligned!\n",1170 __func__, addr, len);1171 }1172 }1173 }1174#endif /* CONFIG_DMA_API_DEBUG */1175 return sg_table;1176}1177EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment, DMA_BUF);1178 1179/**1180 * dma_buf_map_attachment_unlocked - Returns the scatterlist table of the attachment;1181 * mapped into _device_ address space. Is a wrapper for map_dma_buf() of the1182 * dma_buf_ops.1183 * @attach: [in] attachment whose scatterlist is to be returned1184 * @direction: [in] direction of DMA transfer1185 *1186 * Unlocked variant of dma_buf_map_attachment().1187 */1188struct sg_table *1189dma_buf_map_attachment_unlocked(struct dma_buf_attachment *attach,1190 enum dma_data_direction direction)1191{1192 struct sg_table *sg_table;1193 1194 might_sleep();1195 1196 if (WARN_ON(!attach || !attach->dmabuf))1197 return ERR_PTR(-EINVAL);1198 1199 dma_resv_lock(attach->dmabuf->resv, NULL);1200 sg_table = dma_buf_map_attachment(attach, direction);1201 dma_resv_unlock(attach->dmabuf->resv);1202 1203 return sg_table;1204}1205EXPORT_SYMBOL_NS_GPL(dma_buf_map_attachment_unlocked, DMA_BUF);1206 1207/**1208 * dma_buf_unmap_attachment - unmaps and decreases usecount of the buffer;might1209 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of1210 * dma_buf_ops.1211 * @attach: [in] attachment to unmap buffer from1212 * @sg_table: [in] scatterlist info of the buffer to unmap1213 * @direction: [in] direction of DMA transfer1214 *1215 * This unmaps a DMA mapping for @attached obtained by dma_buf_map_attachment().1216 */1217void dma_buf_unmap_attachment(struct dma_buf_attachment *attach,1218 struct sg_table *sg_table,1219 enum dma_data_direction direction)1220{1221 might_sleep();1222 1223 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))1224 return;1225 1226 dma_resv_assert_held(attach->dmabuf->resv);1227 1228 if (attach->sgt == sg_table)1229 return;1230 1231 __unmap_dma_buf(attach, sg_table, direction);1232 1233 if (dma_buf_is_dynamic(attach->dmabuf) &&1234 !IS_ENABLED(CONFIG_DMABUF_MOVE_NOTIFY))1235 dma_buf_unpin(attach);1236}1237EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment, DMA_BUF);1238 1239/**1240 * dma_buf_unmap_attachment_unlocked - unmaps and decreases usecount of the buffer;might1241 * deallocate the scatterlist associated. Is a wrapper for unmap_dma_buf() of1242 * dma_buf_ops.1243 * @attach: [in] attachment to unmap buffer from1244 * @sg_table: [in] scatterlist info of the buffer to unmap1245 * @direction: [in] direction of DMA transfer1246 *1247 * Unlocked variant of dma_buf_unmap_attachment().1248 */1249void dma_buf_unmap_attachment_unlocked(struct dma_buf_attachment *attach,1250 struct sg_table *sg_table,1251 enum dma_data_direction direction)1252{1253 might_sleep();1254 1255 if (WARN_ON(!attach || !attach->dmabuf || !sg_table))1256 return;1257 1258 dma_resv_lock(attach->dmabuf->resv, NULL);1259 dma_buf_unmap_attachment(attach, sg_table, direction);1260 dma_resv_unlock(attach->dmabuf->resv);1261}1262EXPORT_SYMBOL_NS_GPL(dma_buf_unmap_attachment_unlocked, DMA_BUF);1263 1264/**1265 * dma_buf_move_notify - notify attachments that DMA-buf is moving1266 *1267 * @dmabuf: [in] buffer which is moving1268 *1269 * Informs all attachments that they need to destroy and recreate all their1270 * mappings.1271 */1272void dma_buf_move_notify(struct dma_buf *dmabuf)1273{1274 struct dma_buf_attachment *attach;1275 1276 dma_resv_assert_held(dmabuf->resv);1277 1278 list_for_each_entry(attach, &dmabuf->attachments, node)1279 if (attach->importer_ops)1280 attach->importer_ops->move_notify(attach);1281}1282EXPORT_SYMBOL_NS_GPL(dma_buf_move_notify, DMA_BUF);1283 1284/**1285 * DOC: cpu access1286 *1287 * There are multiple reasons for supporting CPU access to a dma buffer object:1288 *1289 * - Fallback operations in the kernel, for example when a device is connected1290 * over USB and the kernel needs to shuffle the data around first before1291 * sending it away. Cache coherency is handled by bracketing any transactions1292 * with calls to dma_buf_begin_cpu_access() and dma_buf_end_cpu_access()1293 * access.1294 *1295 * Since for most kernel internal dma-buf accesses need the entire buffer, a1296 * vmap interface is introduced. Note that on very old 32-bit architectures1297 * vmalloc space might be limited and result in vmap calls failing.1298 *1299 * Interfaces::1300 *1301 * void \*dma_buf_vmap(struct dma_buf \*dmabuf, struct iosys_map \*map)1302 * void dma_buf_vunmap(struct dma_buf \*dmabuf, struct iosys_map \*map)1303 *1304 * The vmap call can fail if there is no vmap support in the exporter, or if1305 * it runs out of vmalloc space. Note that the dma-buf layer keeps a reference1306 * count for all vmap access and calls down into the exporter's vmap function1307 * only when no vmapping exists, and only unmaps it once. Protection against1308 * concurrent vmap/vunmap calls is provided by taking the &dma_buf.lock mutex.1309 *1310 * - For full compatibility on the importer side with existing userspace1311 * interfaces, which might already support mmap'ing buffers. This is needed in1312 * many processing pipelines (e.g. feeding a software rendered image into a1313 * hardware pipeline, thumbnail creation, snapshots, ...). Also, Android's ION1314 * framework already supported this and for DMA buffer file descriptors to1315 * replace ION buffers mmap support was needed.1316 *1317 * There is no special interfaces, userspace simply calls mmap on the dma-buf1318 * fd. But like for CPU access there's a need to bracket the actual access,1319 * which is handled by the ioctl (DMA_BUF_IOCTL_SYNC). Note that1320 * DMA_BUF_IOCTL_SYNC can fail with -EAGAIN or -EINTR, in which case it must1321 * be restarted.1322 *1323 * Some systems might need some sort of cache coherency management e.g. when1324 * CPU and GPU domains are being accessed through dma-buf at the same time.1325 * To circumvent this problem there are begin/end coherency markers, that1326 * forward directly to existing dma-buf device drivers vfunc hooks. Userspace1327 * can make use of those markers through the DMA_BUF_IOCTL_SYNC ioctl. The1328 * sequence would be used like following:1329 *1330 * - mmap dma-buf fd1331 * - for each drawing/upload cycle in CPU 1. SYNC_START ioctl, 2. read/write1332 * to mmap area 3. SYNC_END ioctl. This can be repeated as often as you1333 * want (with the new data being consumed by say the GPU or the scanout1334 * device)1335 * - munmap once you don't need the buffer any more1336 *1337 * For correctness and optimal performance, it is always required to use1338 * SYNC_START and SYNC_END before and after, respectively, when accessing the1339 * mapped address. Userspace cannot rely on coherent access, even when there1340 * are systems where it just works without calling these ioctls.1341 *1342 * - And as a CPU fallback in userspace processing pipelines.1343 *1344 * Similar to the motivation for kernel cpu access it is again important that1345 * the userspace code of a given importing subsystem can use the same1346 * interfaces with a imported dma-buf buffer object as with a native buffer1347 * object. This is especially important for drm where the userspace part of1348 * contemporary OpenGL, X, and other drivers is huge, and reworking them to1349 * use a different way to mmap a buffer rather invasive.1350 *1351 * The assumption in the current dma-buf interfaces is that redirecting the1352 * initial mmap is all that's needed. A survey of some of the existing1353 * subsystems shows that no driver seems to do any nefarious thing like1354 * syncing up with outstanding asynchronous processing on the device or1355 * allocating special resources at fault time. So hopefully this is good1356 * enough, since adding interfaces to intercept pagefaults and allow pte1357 * shootdowns would increase the complexity quite a bit.1358 *1359 * Interface::1360 *1361 * int dma_buf_mmap(struct dma_buf \*, struct vm_area_struct \*,1362 * unsigned long);1363 *1364 * If the importing subsystem simply provides a special-purpose mmap call to1365 * set up a mapping in userspace, calling do_mmap with &dma_buf.file will1366 * equally achieve that for a dma-buf object.1367 */1368 1369static int __dma_buf_begin_cpu_access(struct dma_buf *dmabuf,1370 enum dma_data_direction direction)1371{1372 bool write = (direction == DMA_BIDIRECTIONAL ||1373 direction == DMA_TO_DEVICE);1374 struct dma_resv *resv = dmabuf->resv;1375 long ret;1376 1377 /* Wait on any implicit rendering fences */1378 ret = dma_resv_wait_timeout(resv, dma_resv_usage_rw(write),1379 true, MAX_SCHEDULE_TIMEOUT);1380 if (ret < 0)1381 return ret;1382 1383 return 0;1384}1385 1386/**1387 * dma_buf_begin_cpu_access - Must be called before accessing a dma_buf from the1388 * cpu in the kernel context. Calls begin_cpu_access to allow exporter-specific1389 * preparations. Coherency is only guaranteed in the specified range for the1390 * specified access direction.1391 * @dmabuf: [in] buffer to prepare cpu access for.1392 * @direction: [in] direction of access.1393 *1394 * After the cpu access is complete the caller should call1395 * dma_buf_end_cpu_access(). Only when cpu access is bracketed by both calls is1396 * it guaranteed to be coherent with other DMA access.1397 *1398 * This function will also wait for any DMA transactions tracked through1399 * implicit synchronization in &dma_buf.resv. For DMA transactions with explicit1400 * synchronization this function will only ensure cache coherency, callers must1401 * ensure synchronization with such DMA transactions on their own.1402 *1403 * Can return negative error values, returns 0 on success.1404 */1405int dma_buf_begin_cpu_access(struct dma_buf *dmabuf,1406 enum dma_data_direction direction)1407{1408 int ret = 0;1409 1410 if (WARN_ON(!dmabuf))1411 return -EINVAL;1412 1413 might_lock(&dmabuf->resv->lock.base);1414 1415 if (dmabuf->ops->begin_cpu_access)1416 ret = dmabuf->ops->begin_cpu_access(dmabuf, direction);1417 1418 /* Ensure that all fences are waited upon - but we first allow1419 * the native handler the chance to do so more efficiently if it1420 * chooses. A double invocation here will be reasonably cheap no-op.1421 */1422 if (ret == 0)1423 ret = __dma_buf_begin_cpu_access(dmabuf, direction);1424 1425 return ret;1426}1427EXPORT_SYMBOL_NS_GPL(dma_buf_begin_cpu_access, DMA_BUF);1428 1429/**1430 * dma_buf_end_cpu_access - Must be called after accessing a dma_buf from the1431 * cpu in the kernel context. Calls end_cpu_access to allow exporter-specific1432 * actions. Coherency is only guaranteed in the specified range for the1433 * specified access direction.1434 * @dmabuf: [in] buffer to complete cpu access for.1435 * @direction: [in] direction of access.1436 *1437 * This terminates CPU access started with dma_buf_begin_cpu_access().1438 *1439 * Can return negative error values, returns 0 on success.1440 */1441int dma_buf_end_cpu_access(struct dma_buf *dmabuf,1442 enum dma_data_direction direction)1443{1444 int ret = 0;1445 1446 WARN_ON(!dmabuf);1447 1448 might_lock(&dmabuf->resv->lock.base);1449 1450 if (dmabuf->ops->end_cpu_access)1451 ret = dmabuf->ops->end_cpu_access(dmabuf, direction);1452 1453 return ret;1454}1455EXPORT_SYMBOL_NS_GPL(dma_buf_end_cpu_access, DMA_BUF);1456 1457 1458/**1459 * dma_buf_mmap - Setup up a userspace mmap with the given vma1460 * @dmabuf: [in] buffer that should back the vma1461 * @vma: [in] vma for the mmap1462 * @pgoff: [in] offset in pages where this mmap should start within the1463 * dma-buf buffer.1464 *1465 * This function adjusts the passed in vma so that it points at the file of the1466 * dma_buf operation. It also adjusts the starting pgoff and does bounds1467 * checking on the size of the vma. Then it calls the exporters mmap function to1468 * set up the mapping.1469 *1470 * Can return negative error values, returns 0 on success.1471 */1472int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,1473 unsigned long pgoff)1474{1475 if (WARN_ON(!dmabuf || !vma))1476 return -EINVAL;1477 1478 /* check if buffer supports mmap */1479 if (!dmabuf->ops->mmap)1480 return -EINVAL;1481 1482 /* check for offset overflow */1483 if (pgoff + vma_pages(vma) < pgoff)1484 return -EOVERFLOW;1485 1486 /* check for overflowing the buffer's size */1487 if (pgoff + vma_pages(vma) >1488 dmabuf->size >> PAGE_SHIFT)1489 return -EINVAL;1490 1491 /* readjust the vma */1492 vma_set_file(vma, dmabuf->file);1493 vma->vm_pgoff = pgoff;1494 1495 return dmabuf->ops->mmap(dmabuf, vma);1496}1497EXPORT_SYMBOL_NS_GPL(dma_buf_mmap, DMA_BUF);1498 1499/**1500 * dma_buf_vmap - Create virtual mapping for the buffer object into kernel1501 * address space. Same restrictions as for vmap and friends apply.1502 * @dmabuf: [in] buffer to vmap1503 * @map: [out] returns the vmap pointer1504 *1505 * This call may fail due to lack of virtual mapping address space.1506 * These calls are optional in drivers. The intended use for them1507 * is for mapping objects linear in kernel space for high use objects.1508 *1509 * To ensure coherency users must call dma_buf_begin_cpu_access() and1510 * dma_buf_end_cpu_access() around any cpu access performed through this1511 * mapping.1512 *1513 * Returns 0 on success, or a negative errno code otherwise.1514 */1515int dma_buf_vmap(struct dma_buf *dmabuf, struct iosys_map *map)1516{1517 struct iosys_map ptr;1518 int ret;1519 1520 iosys_map_clear(map);1521 1522 if (WARN_ON(!dmabuf))1523 return -EINVAL;1524 1525 dma_resv_assert_held(dmabuf->resv);1526 1527 if (!dmabuf->ops->vmap)1528 return -EINVAL;1529 1530 if (dmabuf->vmapping_counter) {1531 dmabuf->vmapping_counter++;1532 BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));1533 *map = dmabuf->vmap_ptr;1534 return 0;1535 }1536 1537 BUG_ON(iosys_map_is_set(&dmabuf->vmap_ptr));1538 1539 ret = dmabuf->ops->vmap(dmabuf, &ptr);1540 if (WARN_ON_ONCE(ret))1541 return ret;1542 1543 dmabuf->vmap_ptr = ptr;1544 dmabuf->vmapping_counter = 1;1545 1546 *map = dmabuf->vmap_ptr;1547 1548 return 0;1549}1550EXPORT_SYMBOL_NS_GPL(dma_buf_vmap, DMA_BUF);1551 1552/**1553 * dma_buf_vmap_unlocked - Create virtual mapping for the buffer object into kernel1554 * address space. Same restrictions as for vmap and friends apply.1555 * @dmabuf: [in] buffer to vmap1556 * @map: [out] returns the vmap pointer1557 *1558 * Unlocked version of dma_buf_vmap()1559 *1560 * Returns 0 on success, or a negative errno code otherwise.1561 */1562int dma_buf_vmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)1563{1564 int ret;1565 1566 iosys_map_clear(map);1567 1568 if (WARN_ON(!dmabuf))1569 return -EINVAL;1570 1571 dma_resv_lock(dmabuf->resv, NULL);1572 ret = dma_buf_vmap(dmabuf, map);1573 dma_resv_unlock(dmabuf->resv);1574 1575 return ret;1576}1577EXPORT_SYMBOL_NS_GPL(dma_buf_vmap_unlocked, DMA_BUF);1578 1579/**1580 * dma_buf_vunmap - Unmap a vmap obtained by dma_buf_vmap.1581 * @dmabuf: [in] buffer to vunmap1582 * @map: [in] vmap pointer to vunmap1583 */1584void dma_buf_vunmap(struct dma_buf *dmabuf, struct iosys_map *map)1585{1586 if (WARN_ON(!dmabuf))1587 return;1588 1589 dma_resv_assert_held(dmabuf->resv);1590 1591 BUG_ON(iosys_map_is_null(&dmabuf->vmap_ptr));1592 BUG_ON(dmabuf->vmapping_counter == 0);1593 BUG_ON(!iosys_map_is_equal(&dmabuf->vmap_ptr, map));1594 1595 if (--dmabuf->vmapping_counter == 0) {1596 if (dmabuf->ops->vunmap)1597 dmabuf->ops->vunmap(dmabuf, map);1598 iosys_map_clear(&dmabuf->vmap_ptr);1599 }1600}1601EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap, DMA_BUF);1602 1603/**1604 * dma_buf_vunmap_unlocked - Unmap a vmap obtained by dma_buf_vmap.1605 * @dmabuf: [in] buffer to vunmap1606 * @map: [in] vmap pointer to vunmap1607 */1608void dma_buf_vunmap_unlocked(struct dma_buf *dmabuf, struct iosys_map *map)1609{1610 if (WARN_ON(!dmabuf))1611 return;1612 1613 dma_resv_lock(dmabuf->resv, NULL);1614 dma_buf_vunmap(dmabuf, map);1615 dma_resv_unlock(dmabuf->resv);1616}1617EXPORT_SYMBOL_NS_GPL(dma_buf_vunmap_unlocked, DMA_BUF);1618 1619#ifdef CONFIG_DEBUG_FS1620static int dma_buf_debug_show(struct seq_file *s, void *unused)1621{1622 struct dma_buf *buf_obj;1623 struct dma_buf_attachment *attach_obj;1624 int count = 0, attach_count;1625 size_t size = 0;1626 int ret;1627 1628 ret = mutex_lock_interruptible(&debugfs_list_mutex);1629 1630 if (ret)1631 return ret;1632 1633 seq_puts(s, "\nDma-buf Objects:\n");1634 seq_printf(s, "%-8s\t%-8s\t%-8s\t%-8s\texp_name\t%-8s\tname\n",1635 "size", "flags", "mode", "count", "ino");1636 1637 list_for_each_entry(buf_obj, &debugfs_list, list_node) {1638 1639 ret = dma_resv_lock_interruptible(buf_obj->resv, NULL);1640 if (ret)1641 goto error_unlock;1642 1643 1644 spin_lock(&buf_obj->name_lock);1645 seq_printf(s, "%08zu\t%08x\t%08x\t%08ld\t%s\t%08lu\t%s\n",1646 buf_obj->size,1647 buf_obj->file->f_flags, buf_obj->file->f_mode,1648 file_count(buf_obj->file),1649 buf_obj->exp_name,1650 file_inode(buf_obj->file)->i_ino,1651 buf_obj->name ?: "<none>");1652 spin_unlock(&buf_obj->name_lock);1653 1654 dma_resv_describe(buf_obj->resv, s);1655 1656 seq_puts(s, "\tAttached Devices:\n");1657 attach_count = 0;1658 1659 list_for_each_entry(attach_obj, &buf_obj->attachments, node) {1660 seq_printf(s, "\t%s\n", dev_name(attach_obj->dev));1661 attach_count++;1662 }1663 dma_resv_unlock(buf_obj->resv);1664 1665 seq_printf(s, "Total %d devices attached\n\n",1666 attach_count);1667 1668 count++;1669 size += buf_obj->size;1670 }1671 1672 seq_printf(s, "\nTotal %d objects, %zu bytes\n", count, size);1673 1674 mutex_unlock(&debugfs_list_mutex);1675 return 0;1676 1677error_unlock:1678 mutex_unlock(&debugfs_list_mutex);1679 return ret;1680}1681 1682DEFINE_SHOW_ATTRIBUTE(dma_buf_debug);1683 1684static struct dentry *dma_buf_debugfs_dir;1685 1686static int dma_buf_init_debugfs(void)1687{1688 struct dentry *d;1689 int err = 0;1690 1691 d = debugfs_create_dir("dma_buf", NULL);1692 if (IS_ERR(d))1693 return PTR_ERR(d);1694 1695 dma_buf_debugfs_dir = d;1696 1697 d = debugfs_create_file("bufinfo", S_IRUGO, dma_buf_debugfs_dir,1698 NULL, &dma_buf_debug_fops);1699 if (IS_ERR(d)) {1700 pr_debug("dma_buf: debugfs: failed to create node bufinfo\n");1701 debugfs_remove_recursive(dma_buf_debugfs_dir);1702 dma_buf_debugfs_dir = NULL;1703 err = PTR_ERR(d);1704 }1705 1706 return err;1707}1708 1709static void dma_buf_uninit_debugfs(void)1710{1711 debugfs_remove_recursive(dma_buf_debugfs_dir);1712}1713#else1714static inline int dma_buf_init_debugfs(void)1715{1716 return 0;1717}1718static inline void dma_buf_uninit_debugfs(void)1719{1720}1721#endif1722 1723static int __init dma_buf_init(void)1724{1725 int ret;1726 1727 ret = dma_buf_init_sysfs_statistics();1728 if (ret)1729 return ret;1730 1731 dma_buf_mnt = kern_mount(&dma_buf_fs_type);1732 if (IS_ERR(dma_buf_mnt))1733 return PTR_ERR(dma_buf_mnt);1734 1735 dma_buf_init_debugfs();1736 return 0;1737}1738subsys_initcall(dma_buf_init);1739 1740static void __exit dma_buf_deinit(void)1741{1742 dma_buf_uninit_debugfs();1743 kern_unmount(dma_buf_mnt);1744 dma_buf_uninit_sysfs_statistics();1745}1746__exitcall(dma_buf_deinit);1747