1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Sync File validation framework
4 *
5 * Copyright (C) 2012 Google, Inc.
6 */
7
8#include <linux/file.h>
9#include <linux/fs.h>
10#include <linux/uaccess.h>
11#include <linux/slab.h>
12#include <linux/sync_file.h>
13
14#include "sync_debug.h"
15
16#define CREATE_TRACE_POINTS
17#include "sync_trace.h"
18
19/*
20 * SW SYNC validation framework
21 *
22 * A sync object driver that uses a 32bit counter to coordinate
23 * synchronization. Useful when there is no hardware primitive backing
24 * the synchronization.
25 *
26 * To start the framework just open:
27 *
28 * <debugfs>/sync/sw_sync
29 *
30 * That will create a sync timeline, all fences created under this timeline
31 * file descriptor will belong to the this timeline.
32 *
33 * The 'sw_sync' file can be opened many times as to create different
34 * timelines.
35 *
36 * Fences can be created with SW_SYNC_IOC_CREATE_FENCE ioctl with struct
37 * sw_sync_create_fence_data as parameter.
38 *
39 * To increment the timeline counter, SW_SYNC_IOC_INC ioctl should be used
40 * with the increment as u32. This will update the last signaled value
41 * from the timeline and signal any fence that has a seqno smaller or equal
42 * to it.
43 *
44 * struct sw_sync_create_fence_data
45 * @value: the seqno to initialise the fence with
46 * @name: the name of the new sync point
47 * @fence: return the fd of the new sync_file with the created fence
48 */
49struct sw_sync_create_fence_data {
50 __u32 value;
51 char name[32];
52 __s32 fence; /* fd of new fence */
53};
54
55/**
56 * struct sw_sync_get_deadline - get the deadline hint of a sw_sync fence
57 * @deadline_ns: absolute time of the deadline
58 * @pad: must be zero
59 * @fence_fd: the sw_sync fence fd (in)
60 *
61 * Return the earliest deadline set on the fence. The timebase for the
62 * deadline is CLOCK_MONOTONIC (same as vblank). If there is no deadline
63 * set on the fence, this ioctl will return -ENOENT.
64 */
65struct sw_sync_get_deadline {
66 __u64 deadline_ns;
67 __u32 pad;
68 __s32 fence_fd;
69};
70
71#define SW_SYNC_IOC_MAGIC 'W'
72
73#define SW_SYNC_IOC_CREATE_FENCE _IOWR(SW_SYNC_IOC_MAGIC, 0,\
74 struct sw_sync_create_fence_data)
75
76#define SW_SYNC_IOC_INC _IOW(SW_SYNC_IOC_MAGIC, 1, __u32)
77#define SW_SYNC_GET_DEADLINE _IOWR(SW_SYNC_IOC_MAGIC, 2, \
78 struct sw_sync_get_deadline)
79
80
81#define SW_SYNC_HAS_DEADLINE_BIT DMA_FENCE_FLAG_USER_BITS
82
83static const struct dma_fence_ops timeline_fence_ops;
84
85static inline struct sync_pt *dma_fence_to_sync_pt(struct dma_fence *fence)
86{
87 if (fence->ops != &timeline_fence_ops)
88 return NULL;
89 return container_of(fence, struct sync_pt, base);
90}
91
92/**
93 * sync_timeline_create() - creates a sync object
94 * @name: sync_timeline name
95 *
96 * Creates a new sync_timeline. Returns the sync_timeline object or NULL in
97 * case of error.
98 */
99static struct sync_timeline *sync_timeline_create(const char *name)
100{
101 struct sync_timeline *obj;
102
103 obj = kzalloc(size: sizeof(*obj), GFP_KERNEL);
104 if (!obj)
105 return NULL;
106
107 kref_init(kref: &obj->kref);
108 obj->context = dma_fence_context_alloc(num: 1);
109 strscpy(obj->name, name, sizeof(obj->name));
110
111 obj->pt_tree = RB_ROOT;
112 INIT_LIST_HEAD(list: &obj->pt_list);
113 spin_lock_init(&obj->lock);
114
115 sync_timeline_debug_add(obj);
116
117 return obj;
118}
119
120static void sync_timeline_free(struct kref *kref)
121{
122 struct sync_timeline *obj =
123 container_of(kref, struct sync_timeline, kref);
124
125 sync_timeline_debug_remove(obj);
126
127 kfree(objp: obj);
128}
129
130static void sync_timeline_get(struct sync_timeline *obj)
131{
132 kref_get(kref: &obj->kref);
133}
134
135static void sync_timeline_put(struct sync_timeline *obj)
136{
137 kref_put(kref: &obj->kref, release: sync_timeline_free);
138}
139
140static const char *timeline_fence_get_driver_name(struct dma_fence *fence)
141{
142 return "sw_sync";
143}
144
145static const char *timeline_fence_get_timeline_name(struct dma_fence *fence)
146{
147 struct sync_timeline *parent = dma_fence_parent(fence);
148
149 return parent->name;
150}
151
152static void timeline_fence_release(struct dma_fence *fence)
153{
154 struct sync_pt *pt = dma_fence_to_sync_pt(fence);
155 struct sync_timeline *parent = dma_fence_parent(fence);
156 unsigned long flags;
157
158 spin_lock_irqsave(fence->lock, flags);
159 if (!list_empty(head: &pt->link)) {
160 list_del(entry: &pt->link);
161 rb_erase(&pt->node, &parent->pt_tree);
162 }
163 spin_unlock_irqrestore(lock: fence->lock, flags);
164
165 sync_timeline_put(obj: parent);
166 dma_fence_free(fence);
167}
168
169static bool timeline_fence_signaled(struct dma_fence *fence)
170{
171 struct sync_timeline *parent = dma_fence_parent(fence);
172
173 return !__dma_fence_is_later(f1: fence->seqno, f2: parent->value, ops: fence->ops);
174}
175
176static bool timeline_fence_enable_signaling(struct dma_fence *fence)
177{
178 return true;
179}
180
181static void timeline_fence_value_str(struct dma_fence *fence,
182 char *str, int size)
183{
184 snprintf(buf: str, size, fmt: "%lld", fence->seqno);
185}
186
187static void timeline_fence_timeline_value_str(struct dma_fence *fence,
188 char *str, int size)
189{
190 struct sync_timeline *parent = dma_fence_parent(fence);
191
192 snprintf(buf: str, size, fmt: "%d", parent->value);
193}
194
195static void timeline_fence_set_deadline(struct dma_fence *fence, ktime_t deadline)
196{
197 struct sync_pt *pt = dma_fence_to_sync_pt(fence);
198 unsigned long flags;
199
200 spin_lock_irqsave(fence->lock, flags);
201 if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
202 if (ktime_before(cmp1: deadline, cmp2: pt->deadline))
203 pt->deadline = deadline;
204 } else {
205 pt->deadline = deadline;
206 __set_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags);
207 }
208 spin_unlock_irqrestore(lock: fence->lock, flags);
209}
210
211static const struct dma_fence_ops timeline_fence_ops = {
212 .get_driver_name = timeline_fence_get_driver_name,
213 .get_timeline_name = timeline_fence_get_timeline_name,
214 .enable_signaling = timeline_fence_enable_signaling,
215 .signaled = timeline_fence_signaled,
216 .release = timeline_fence_release,
217 .fence_value_str = timeline_fence_value_str,
218 .timeline_value_str = timeline_fence_timeline_value_str,
219 .set_deadline = timeline_fence_set_deadline,
220};
221
222/**
223 * sync_timeline_signal() - signal a status change on a sync_timeline
224 * @obj: sync_timeline to signal
225 * @inc: num to increment on timeline->value
226 *
227 * A sync implementation should call this any time one of it's fences
228 * has signaled or has an error condition.
229 */
230static void sync_timeline_signal(struct sync_timeline *obj, unsigned int inc)
231{
232 LIST_HEAD(signalled);
233 struct sync_pt *pt, *next;
234
235 trace_sync_timeline(timeline: obj);
236
237 spin_lock_irq(lock: &obj->lock);
238
239 obj->value += inc;
240
241 list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
242 if (!timeline_fence_signaled(fence: &pt->base))
243 break;
244
245 dma_fence_get(fence: &pt->base);
246
247 list_move_tail(list: &pt->link, head: &signalled);
248 rb_erase(&pt->node, &obj->pt_tree);
249
250 dma_fence_signal_locked(fence: &pt->base);
251 }
252
253 spin_unlock_irq(lock: &obj->lock);
254
255 list_for_each_entry_safe(pt, next, &signalled, link) {
256 list_del_init(entry: &pt->link);
257 dma_fence_put(fence: &pt->base);
258 }
259}
260
261/**
262 * sync_pt_create() - creates a sync pt
263 * @obj: parent sync_timeline
264 * @value: value of the fence
265 *
266 * Creates a new sync_pt (fence) as a child of @parent. @size bytes will be
267 * allocated allowing for implementation specific data to be kept after
268 * the generic sync_timeline struct. Returns the sync_pt object or
269 * NULL in case of error.
270 */
271static struct sync_pt *sync_pt_create(struct sync_timeline *obj,
272 unsigned int value)
273{
274 struct sync_pt *pt;
275
276 pt = kzalloc(size: sizeof(*pt), GFP_KERNEL);
277 if (!pt)
278 return NULL;
279
280 sync_timeline_get(obj);
281 dma_fence_init(fence: &pt->base, ops: &timeline_fence_ops, lock: &obj->lock,
282 context: obj->context, seqno: value);
283 INIT_LIST_HEAD(list: &pt->link);
284
285 spin_lock_irq(lock: &obj->lock);
286 if (!dma_fence_is_signaled_locked(fence: &pt->base)) {
287 struct rb_node **p = &obj->pt_tree.rb_node;
288 struct rb_node *parent = NULL;
289
290 while (*p) {
291 struct sync_pt *other;
292 int cmp;
293
294 parent = *p;
295 other = rb_entry(parent, typeof(*pt), node);
296 cmp = value - other->base.seqno;
297 if (cmp > 0) {
298 p = &parent->rb_right;
299 } else if (cmp < 0) {
300 p = &parent->rb_left;
301 } else {
302 if (dma_fence_get_rcu(fence: &other->base)) {
303 sync_timeline_put(obj);
304 kfree(objp: pt);
305 pt = other;
306 goto unlock;
307 }
308 p = &parent->rb_left;
309 }
310 }
311 rb_link_node(node: &pt->node, parent, rb_link: p);
312 rb_insert_color(&pt->node, &obj->pt_tree);
313
314 parent = rb_next(&pt->node);
315 list_add_tail(new: &pt->link,
316 head: parent ? &rb_entry(parent, typeof(*pt), node)->link : &obj->pt_list);
317 }
318unlock:
319 spin_unlock_irq(lock: &obj->lock);
320
321 return pt;
322}
323
324/*
325 * *WARNING*
326 *
327 * improper use of this can result in deadlocking kernel drivers from userspace.
328 */
329
330/* opening sw_sync create a new sync obj */
331static int sw_sync_debugfs_open(struct inode *inode, struct file *file)
332{
333 struct sync_timeline *obj;
334 char task_comm[TASK_COMM_LEN];
335
336 get_task_comm(task_comm, current);
337
338 obj = sync_timeline_create(name: task_comm);
339 if (!obj)
340 return -ENOMEM;
341
342 file->private_data = obj;
343
344 return 0;
345}
346
347static int sw_sync_debugfs_release(struct inode *inode, struct file *file)
348{
349 struct sync_timeline *obj = file->private_data;
350 struct sync_pt *pt, *next;
351
352 spin_lock_irq(lock: &obj->lock);
353
354 list_for_each_entry_safe(pt, next, &obj->pt_list, link) {
355 dma_fence_set_error(fence: &pt->base, error: -ENOENT);
356 dma_fence_signal_locked(fence: &pt->base);
357 }
358
359 spin_unlock_irq(lock: &obj->lock);
360
361 sync_timeline_put(obj);
362 return 0;
363}
364
365static long sw_sync_ioctl_create_fence(struct sync_timeline *obj,
366 unsigned long arg)
367{
368 int fd = get_unused_fd_flags(O_CLOEXEC);
369 int err;
370 struct sync_pt *pt;
371 struct sync_file *sync_file;
372 struct sw_sync_create_fence_data data;
373
374 if (fd < 0)
375 return fd;
376
377 if (copy_from_user(to: &data, from: (void __user *)arg, n: sizeof(data))) {
378 err = -EFAULT;
379 goto err;
380 }
381
382 pt = sync_pt_create(obj, value: data.value);
383 if (!pt) {
384 err = -ENOMEM;
385 goto err;
386 }
387
388 sync_file = sync_file_create(fence: &pt->base);
389 dma_fence_put(fence: &pt->base);
390 if (!sync_file) {
391 err = -ENOMEM;
392 goto err;
393 }
394
395 data.fence = fd;
396 if (copy_to_user(to: (void __user *)arg, from: &data, n: sizeof(data))) {
397 fput(sync_file->file);
398 err = -EFAULT;
399 goto err;
400 }
401
402 fd_install(fd, file: sync_file->file);
403
404 return 0;
405
406err:
407 put_unused_fd(fd);
408 return err;
409}
410
411static long sw_sync_ioctl_inc(struct sync_timeline *obj, unsigned long arg)
412{
413 u32 value;
414
415 if (copy_from_user(to: &value, from: (void __user *)arg, n: sizeof(value)))
416 return -EFAULT;
417
418 while (value > INT_MAX) {
419 sync_timeline_signal(obj, INT_MAX);
420 value -= INT_MAX;
421 }
422
423 sync_timeline_signal(obj, inc: value);
424
425 return 0;
426}
427
428static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long arg)
429{
430 struct sw_sync_get_deadline data;
431 struct dma_fence *fence;
432 unsigned long flags;
433 struct sync_pt *pt;
434 int ret = 0;
435
436 if (copy_from_user(to: &data, from: (void __user *)arg, n: sizeof(data)))
437 return -EFAULT;
438
439 if (data.deadline_ns || data.pad)
440 return -EINVAL;
441
442 fence = sync_file_get_fence(fd: data.fence_fd);
443 if (!fence)
444 return -EINVAL;
445
446 pt = dma_fence_to_sync_pt(fence);
447 if (!pt)
448 return -EINVAL;
449
450 spin_lock_irqsave(fence->lock, flags);
451 if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
452 data.deadline_ns = ktime_to_ns(kt: pt->deadline);
453 } else {
454 ret = -ENOENT;
455 }
456 spin_unlock_irqrestore(lock: fence->lock, flags);
457
458 dma_fence_put(fence);
459
460 if (ret)
461 return ret;
462
463 if (copy_to_user(to: (void __user *)arg, from: &data, n: sizeof(data)))
464 return -EFAULT;
465
466 return 0;
467}
468
469static long sw_sync_ioctl(struct file *file, unsigned int cmd,
470 unsigned long arg)
471{
472 struct sync_timeline *obj = file->private_data;
473
474 switch (cmd) {
475 case SW_SYNC_IOC_CREATE_FENCE:
476 return sw_sync_ioctl_create_fence(obj, arg);
477
478 case SW_SYNC_IOC_INC:
479 return sw_sync_ioctl_inc(obj, arg);
480
481 case SW_SYNC_GET_DEADLINE:
482 return sw_sync_ioctl_get_deadline(obj, arg);
483
484 default:
485 return -ENOTTY;
486 }
487}
488
489const struct file_operations sw_sync_debugfs_fops = {
490 .open = sw_sync_debugfs_open,
491 .release = sw_sync_debugfs_release,
492 .unlocked_ioctl = sw_sync_ioctl,
493 .compat_ioctl = compat_ptr_ioctl,
494};
495

source code of linux/drivers/dma-buf/sw_sync.c