1 // SPDX-License-Identifier: MIT
3 * Copyright 2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 #include <side/trace.h>
13 /* Top 8 bits reserved for kernel tracer use. */
14 #if SIDE_BITS_PER_LONG == 64
15 # define SIDE_EVENT_ENABLED_KERNEL_MASK 0xFF00000000000000ULL
16 # define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 0x8000000000000000ULL
18 /* Allow 2^56 tracer references on an event. */
19 # define SIDE_EVENT_ENABLED_USER_MASK 0x00FFFFFFFFFFFFFFULL
21 # define SIDE_EVENT_ENABLED_KERNEL_MASK 0xFF000000UL
22 # define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 0x80000000UL
24 /* Allow 2^24 tracer references on an event. */
25 # define SIDE_EVENT_ENABLED_USER_MASK 0x00FFFFFFUL
28 struct side_events_register_handle
{
29 struct side_list_node node
;
30 struct side_event_description
**events
;
34 struct side_tracer_handle
{
35 struct side_list_node node
;
36 void (*cb
)(enum side_tracer_notification notif
,
37 struct side_event_description
**events
, uint32_t nr_events
, void *priv
);
41 struct side_callback
{
43 void (*call
)(const struct side_event_description
*desc
,
44 const struct side_arg_vec
*side_arg_vec
,
46 void (*call_variadic
)(const struct side_event_description
*desc
,
47 const struct side_arg_vec
*side_arg_vec
,
48 const struct side_arg_dynamic_struct
*var_struct
,
55 static struct side_rcu_gp_state rcu_gp
;
58 * Lazy initialization for early use within library constructors.
60 static bool initialized
;
62 * Do not register/unregister any more events after destructor.
64 static bool finalized
;
67 * Recursive mutex to allow tracer callbacks to use the side API.
69 static pthread_mutex_t side_lock
= PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
;
71 static DEFINE_SIDE_LIST_HEAD(side_events_list
);
72 static DEFINE_SIDE_LIST_HEAD(side_tracer_list
);
75 * The empty callback has a NULL function callback pointer, which stops
76 * iteration on the array of callbacks immediately.
78 const char side_empty_callback
[sizeof(struct side_callback
)];
80 void side_call_key(const struct side_event_state
*event_state
, const struct side_arg_vec
*side_arg_vec
, void *key
)
82 struct side_rcu_read_state rcu_read_state
;
83 const struct side_event_state_0
*es0
;
84 const struct side_callback
*side_cb
;
87 if (side_unlikely(finalized
))
89 if (side_unlikely(!initialized
))
91 if (side_unlikely(event_state
->version
!= 0))
93 es0
= side_container_of(event_state
, const struct side_event_state_0
, parent
);
94 assert(!(es0
->desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
));
95 enabled
= __atomic_load_n(&es0
->enabled
, __ATOMIC_RELAXED
);
96 if (side_unlikely(enabled
& SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK
)) {
97 // TODO: call kernel write.
99 side_rcu_read_begin(&rcu_gp
, &rcu_read_state
);
100 for (side_cb
= side_rcu_dereference(es0
->callbacks
); side_cb
->u
.call
!= NULL
; side_cb
++) {
101 /* A NULL key is always a match. */
102 if (key
&& side_cb
->key
&& side_cb
->key
!= key
)
104 side_cb
->u
.call(es0
->desc
, side_arg_vec
, side_cb
->priv
);
106 side_rcu_read_end(&rcu_gp
, &rcu_read_state
);
109 void side_call(const struct side_event_state
*event_state
, const struct side_arg_vec
*side_arg_vec
)
111 side_call_key(event_state
, side_arg_vec
, NULL
);
114 void side_call_variadic_key(const struct side_event_state
*event_state
,
115 const struct side_arg_vec
*side_arg_vec
,
116 const struct side_arg_dynamic_struct
*var_struct
,
119 struct side_rcu_read_state rcu_read_state
;
120 const struct side_event_state_0
*es0
;
121 const struct side_callback
*side_cb
;
124 if (side_unlikely(finalized
))
126 if (side_unlikely(!initialized
))
128 if (side_unlikely(event_state
->version
!= 0))
130 es0
= side_container_of(event_state
, const struct side_event_state_0
, parent
);
131 assert(es0
->desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
);
132 enabled
= __atomic_load_n(&es0
->enabled
, __ATOMIC_RELAXED
);
133 if (side_unlikely(enabled
& SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK
)) {
134 // TODO: call kernel write.
136 side_rcu_read_begin(&rcu_gp
, &rcu_read_state
);
137 for (side_cb
= side_rcu_dereference(es0
->callbacks
); side_cb
->u
.call_variadic
!= NULL
; side_cb
++) {
138 /* A NULL key is always a match. */
139 if (key
&& side_cb
->key
&& side_cb
->key
!= key
)
141 side_cb
->u
.call_variadic(es0
->desc
, side_arg_vec
, var_struct
, side_cb
->priv
);
143 side_rcu_read_end(&rcu_gp
, &rcu_read_state
);
146 void side_call_variadic(const struct side_event_state
*event_state
,
147 const struct side_arg_vec
*side_arg_vec
,
148 const struct side_arg_dynamic_struct
*var_struct
)
150 side_call_variadic_key(event_state
, side_arg_vec
, var_struct
, NULL
);
154 const struct side_callback
*side_tracer_callback_lookup(
155 const struct side_event_description
*desc
,
156 void *call
, void *priv
, void *key
)
158 struct side_event_state
*event_state
= side_ptr_get(desc
->state
);
159 const struct side_event_state_0
*es0
;
160 const struct side_callback
*cb
;
162 if (side_unlikely(event_state
->version
!= 0))
164 es0
= side_container_of(event_state
, const struct side_event_state_0
, parent
);
165 for (cb
= es0
->callbacks
; cb
->u
.call
!= NULL
; cb
++) {
166 if ((void *) cb
->u
.call
== call
&& cb
->priv
== priv
&& cb
->key
== key
)
173 int _side_tracer_callback_register(struct side_event_description
*desc
,
174 void *call
, void *priv
, void *key
)
176 struct side_event_state
*event_state
;
177 struct side_callback
*old_cb
, *new_cb
;
178 struct side_event_state_0
*es0
;
179 int ret
= SIDE_ERROR_OK
;
183 return SIDE_ERROR_INVAL
;
185 return SIDE_ERROR_EXITING
;
188 pthread_mutex_lock(&side_lock
);
189 event_state
= side_ptr_get(desc
->state
);
190 if (side_unlikely(event_state
->version
!= 0))
192 es0
= side_container_of(event_state
, struct side_event_state_0
, parent
);
193 old_nr_cb
= es0
->nr_callbacks
;
194 if (old_nr_cb
== UINT32_MAX
) {
195 ret
= SIDE_ERROR_INVAL
;
198 /* Reject duplicate (call, priv) tuples. */
199 if (side_tracer_callback_lookup(desc
, call
, priv
, key
)) {
200 ret
= SIDE_ERROR_EXIST
;
203 old_cb
= (struct side_callback
*) es0
->callbacks
;
204 /* old_nr_cb + 1 (new cb) + 1 (NULL) */
205 new_cb
= (struct side_callback
*) calloc(old_nr_cb
+ 2, sizeof(struct side_callback
));
207 ret
= SIDE_ERROR_NOMEM
;
210 memcpy(new_cb
, old_cb
, old_nr_cb
);
211 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
212 new_cb
[old_nr_cb
].u
.call_variadic
=
213 (side_tracer_callback_variadic_func
) call
;
215 new_cb
[old_nr_cb
].u
.call
=
216 (side_tracer_callback_func
) call
;
217 new_cb
[old_nr_cb
].priv
= priv
;
218 new_cb
[old_nr_cb
].key
= key
;
219 /* High order bits are already zeroed. */
220 side_rcu_assign_pointer(es0
->callbacks
, new_cb
);
221 side_rcu_wait_grace_period(&rcu_gp
);
225 /* Increment concurrently with kernel setting the top bits. */
227 (void) __atomic_add_fetch(&es0
->enabled
, 1, __ATOMIC_RELAXED
);
229 pthread_mutex_unlock(&side_lock
);
233 int side_tracer_callback_register(struct side_event_description
*desc
,
234 side_tracer_callback_func call
,
235 void *priv
, void *key
)
237 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
238 return SIDE_ERROR_INVAL
;
239 return _side_tracer_callback_register(desc
, (void *) call
, priv
, key
);
242 int side_tracer_callback_variadic_register(struct side_event_description
*desc
,
243 side_tracer_callback_variadic_func call_variadic
,
244 void *priv
, void *key
)
246 if (!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))
247 return SIDE_ERROR_INVAL
;
248 return _side_tracer_callback_register(desc
, (void *) call_variadic
, priv
, key
);
251 static int _side_tracer_callback_unregister(struct side_event_description
*desc
,
252 void *call
, void *priv
, void *key
)
254 struct side_event_state
*event_state
;
255 struct side_callback
*old_cb
, *new_cb
;
256 const struct side_callback
*cb_pos
;
257 struct side_event_state_0
*es0
;
259 int ret
= SIDE_ERROR_OK
;
263 return SIDE_ERROR_INVAL
;
265 return SIDE_ERROR_EXITING
;
268 pthread_mutex_lock(&side_lock
);
269 event_state
= side_ptr_get(desc
->state
);
270 if (side_unlikely(event_state
->version
!= 0))
272 es0
= side_container_of(event_state
, struct side_event_state_0
, parent
);
273 cb_pos
= side_tracer_callback_lookup(desc
, call
, priv
, key
);
275 ret
= SIDE_ERROR_NOENT
;
278 old_nr_cb
= es0
->nr_callbacks
;
279 old_cb
= (struct side_callback
*) es0
->callbacks
;
280 if (old_nr_cb
== 1) {
281 new_cb
= (struct side_callback
*) &side_empty_callback
;
283 pos_idx
= cb_pos
- es0
->callbacks
;
284 /* Remove entry at pos_idx. */
285 /* old_nr_cb - 1 (removed cb) + 1 (NULL) */
286 new_cb
= (struct side_callback
*) calloc(old_nr_cb
, sizeof(struct side_callback
));
288 ret
= SIDE_ERROR_NOMEM
;
291 memcpy(new_cb
, old_cb
, pos_idx
);
292 memcpy(&new_cb
[pos_idx
], &old_cb
[pos_idx
+ 1], old_nr_cb
- pos_idx
- 1);
294 /* High order bits are already zeroed. */
295 side_rcu_assign_pointer(es0
->callbacks
, new_cb
);
296 side_rcu_wait_grace_period(&rcu_gp
);
299 /* Decrement concurrently with kernel setting the top bits. */
301 (void) __atomic_add_fetch(&es0
->enabled
, -1, __ATOMIC_RELAXED
);
303 pthread_mutex_unlock(&side_lock
);
307 int side_tracer_callback_unregister(struct side_event_description
*desc
,
308 side_tracer_callback_func call
,
309 void *priv
, void *key
)
311 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
312 return SIDE_ERROR_INVAL
;
313 return _side_tracer_callback_unregister(desc
, (void *) call
, priv
, key
);
316 int side_tracer_callback_variadic_unregister(struct side_event_description
*desc
,
317 side_tracer_callback_variadic_func call_variadic
,
318 void *priv
, void *key
)
320 if (!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))
321 return SIDE_ERROR_INVAL
;
322 return _side_tracer_callback_unregister(desc
, (void *) call_variadic
, priv
, key
);
325 struct side_events_register_handle
*side_events_register(struct side_event_description
**events
, uint32_t nr_events
)
327 struct side_events_register_handle
*events_handle
= NULL
;
328 struct side_tracer_handle
*tracer_handle
;
334 events_handle
= (struct side_events_register_handle
*)
335 calloc(1, sizeof(struct side_events_register_handle
));
338 events_handle
->events
= events
;
339 events_handle
->nr_events
= nr_events
;
341 pthread_mutex_lock(&side_lock
);
342 side_list_insert_node_tail(&side_events_list
, &events_handle
->node
);
343 side_list_for_each_entry(tracer_handle
, &side_tracer_list
, node
) {
344 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS
,
345 events
, nr_events
, tracer_handle
->priv
);
347 pthread_mutex_unlock(&side_lock
);
348 //TODO: call event batch register ioctl
349 return events_handle
;
353 void side_event_remove_callbacks(struct side_event_description
*desc
)
355 struct side_event_state
*event_state
= side_ptr_get(desc
->state
);
356 struct side_event_state_0
*es0
;
357 struct side_callback
*old_cb
;
360 if (side_unlikely(event_state
->version
!= 0))
362 es0
= side_container_of(event_state
, struct side_event_state_0
, parent
);
363 nr_cb
= es0
->nr_callbacks
;
366 old_cb
= (struct side_callback
*) es0
->callbacks
;
367 (void) __atomic_add_fetch(&es0
->enabled
, -1, __ATOMIC_RELAXED
);
369 * Setting the state back to 0 cb and empty callbacks out of
370 * caution. This should not matter because instrumentation is
373 es0
->nr_callbacks
= 0;
374 side_rcu_assign_pointer(es0
->callbacks
, &side_empty_callback
);
376 * No need to wait for grace period because instrumentation is
383 * Unregister event handle. At this point, all side events in that
384 * handle should be unreachable.
386 void side_events_unregister(struct side_events_register_handle
*events_handle
)
388 struct side_tracer_handle
*tracer_handle
;
397 pthread_mutex_lock(&side_lock
);
398 side_list_remove_node(&events_handle
->node
);
399 side_list_for_each_entry(tracer_handle
, &side_tracer_list
, node
) {
400 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS
,
401 events_handle
->events
, events_handle
->nr_events
,
402 tracer_handle
->priv
);
404 for (i
= 0; i
< events_handle
->nr_events
; i
++) {
405 struct side_event_description
*event
= events_handle
->events
[i
];
407 /* Skip NULL pointers */
410 side_event_remove_callbacks(event
);
412 pthread_mutex_unlock(&side_lock
);
413 //TODO: call event batch unregister ioctl
417 struct side_tracer_handle
*side_tracer_event_notification_register(
418 void (*cb
)(enum side_tracer_notification notif
,
419 struct side_event_description
**events
, uint32_t nr_events
, void *priv
),
422 struct side_tracer_handle
*tracer_handle
;
423 struct side_events_register_handle
*events_handle
;
429 tracer_handle
= (struct side_tracer_handle
*)
430 calloc(1, sizeof(struct side_tracer_handle
));
433 pthread_mutex_lock(&side_lock
);
434 tracer_handle
->cb
= cb
;
435 tracer_handle
->priv
= priv
;
436 side_list_insert_node_tail(&side_tracer_list
, &tracer_handle
->node
);
437 side_list_for_each_entry(events_handle
, &side_events_list
, node
) {
438 cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS
,
439 events_handle
->events
, events_handle
->nr_events
, priv
);
441 pthread_mutex_unlock(&side_lock
);
442 return tracer_handle
;
445 void side_tracer_event_notification_unregister(struct side_tracer_handle
*tracer_handle
)
447 struct side_events_register_handle
*events_handle
;
453 pthread_mutex_lock(&side_lock
);
454 side_list_for_each_entry(events_handle
, &side_events_list
, node
) {
455 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS
,
456 events_handle
->events
, events_handle
->nr_events
,
457 tracer_handle
->priv
);
459 side_list_remove_node(&tracer_handle
->node
);
460 pthread_mutex_unlock(&side_lock
);
468 side_rcu_gp_init(&rcu_gp
);
473 * side_exit() is executed from a library destructor. It can be called
474 * explicitly at application exit as well. Concurrent side API use is
475 * not expected at that point.
479 struct side_events_register_handle
*handle
, *tmp
;
483 side_list_for_each_entry_safe(handle
, tmp
, &side_events_list
, node
)
484 side_events_unregister(handle
);
485 side_rcu_gp_exit(&rcu_gp
);