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 #define SIDE_EVENT_ENABLED_KERNEL_MASK 0xFF000000
15 #define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 0x80000000
17 /* Allow 2^24 tracer callbacks to be registered on an event. */
18 #define SIDE_EVENT_ENABLED_USER_MASK 0x00FFFFFF
20 struct side_events_register_handle
{
21 struct side_list_node node
;
22 struct side_event_description
**events
;
26 struct side_tracer_handle
{
27 struct side_list_node node
;
28 void (*cb
)(enum side_tracer_notification notif
,
29 struct side_event_description
**events
, uint32_t nr_events
, void *priv
);
33 static struct side_rcu_gp_state rcu_gp
;
36 * Lazy initialization for early use within library constructors.
38 static bool initialized
;
40 * Do not register/unregister any more events after destructor.
42 static bool finalized
;
44 static pthread_mutex_t side_lock
= PTHREAD_MUTEX_INITIALIZER
;
46 static DEFINE_SIDE_LIST_HEAD(side_events_list
);
47 static DEFINE_SIDE_LIST_HEAD(side_tracer_list
);
50 * The empty callback has a NULL function callback pointer, which stops
51 * iteration on the array of callbacks immediately.
53 const struct side_callback side_empty_callback
;
55 void side_init(void) __attribute__((constructor
));
56 void side_exit(void) __attribute__((destructor
));
58 void side_call(const struct side_event_description
*desc
, const struct side_arg_vec_description
*sav_desc
)
60 const struct side_callback
*side_cb
;
61 unsigned int rcu_period
;
64 if (side_unlikely(finalized
))
66 if (side_unlikely(!initialized
))
68 if (side_unlikely(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)) {
69 printf("ERROR: unexpected variadic event description\n");
72 enabled
= __atomic_load_n(desc
->enabled
, __ATOMIC_RELAXED
);
73 if (side_unlikely(enabled
& SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK
)) {
74 // TODO: call kernel write.
76 if (side_unlikely(!(enabled
& SIDE_EVENT_ENABLED_USER_MASK
)))
79 rcu_period
= side_rcu_read_begin(&rcu_gp
);
80 for (side_cb
= side_rcu_dereference(desc
->callbacks
); side_cb
->u
.call
!= NULL
; side_cb
++)
81 side_cb
->u
.call(desc
, sav_desc
, side_cb
->priv
);
82 side_rcu_read_end(&rcu_gp
, rcu_period
);
85 void side_call_variadic(const struct side_event_description
*desc
,
86 const struct side_arg_vec_description
*sav_desc
,
87 const struct side_arg_dynamic_event_struct
*var_struct
)
89 const struct side_callback
*side_cb
;
90 unsigned int rcu_period
;
93 if (side_unlikely(finalized
))
95 if (side_unlikely(!initialized
))
97 if (side_unlikely(!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))) {
98 printf("ERROR: unexpected non-variadic event description\n");
101 enabled
= __atomic_load_n(desc
->enabled
, __ATOMIC_RELAXED
);
102 if (side_unlikely(enabled
& SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK
)) {
103 // TODO: call kernel write.
105 if (side_unlikely(!(enabled
& SIDE_EVENT_ENABLED_USER_MASK
)))
108 rcu_period
= side_rcu_read_begin(&rcu_gp
);
109 for (side_cb
= side_rcu_dereference(desc
->callbacks
); side_cb
->u
.call_variadic
!= NULL
; side_cb
++)
110 side_cb
->u
.call_variadic(desc
, sav_desc
, var_struct
, side_cb
->priv
);
111 side_rcu_read_end(&rcu_gp
, rcu_period
);
115 const struct side_callback
*side_tracer_callback_lookup(
116 const struct side_event_description
*desc
,
117 void (*call
)(), void *priv
)
119 const struct side_callback
*cb
;
121 for (cb
= desc
->callbacks
; cb
->u
.call
!= NULL
; cb
++) {
122 if (cb
->u
.call
== call
&& cb
->priv
== priv
)
129 int _side_tracer_callback_register(struct side_event_description
*desc
,
130 void (*call
)(), void *priv
)
132 struct side_callback
*old_cb
, *new_cb
;
133 int ret
= SIDE_ERROR_OK
;
137 return SIDE_ERROR_INVAL
;
139 return SIDE_ERROR_EXITING
;
142 pthread_mutex_lock(&side_lock
);
143 old_nr_cb
= *desc
->enabled
& SIDE_EVENT_ENABLED_USER_MASK
;
144 if (old_nr_cb
== SIDE_EVENT_ENABLED_USER_MASK
) {
145 ret
= SIDE_ERROR_INVAL
;
148 /* Reject duplicate (call, priv) tuples. */
149 if (side_tracer_callback_lookup(desc
, call
, priv
)) {
150 ret
= SIDE_ERROR_EXIST
;
153 old_cb
= (struct side_callback
*) desc
->callbacks
;
154 /* old_nr_cb + 1 (new cb) + 1 (NULL) */
155 new_cb
= (struct side_callback
*) calloc(old_nr_cb
+ 2, sizeof(struct side_callback
));
157 ret
= SIDE_ERROR_NOMEM
;
160 memcpy(new_cb
, old_cb
, old_nr_cb
);
161 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
162 new_cb
[old_nr_cb
].u
.call_variadic
= call
;
164 new_cb
[old_nr_cb
].u
.call
= call
;
165 new_cb
[old_nr_cb
].priv
= priv
;
166 side_rcu_assign_pointer(desc
->callbacks
, new_cb
);
167 side_rcu_wait_grace_period(&rcu_gp
);
170 /* Increment concurrently with kernel setting the top bits. */
171 (void) __atomic_add_fetch(desc
->enabled
, 1, __ATOMIC_RELAXED
);
173 pthread_mutex_unlock(&side_lock
);
177 int side_tracer_callback_register(struct side_event_description
*desc
,
178 void (*call
)(const struct side_event_description
*desc
,
179 const struct side_arg_vec_description
*sav_desc
,
183 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
184 return SIDE_ERROR_INVAL
;
185 return _side_tracer_callback_register(desc
, call
, priv
);
188 int side_tracer_callback_variadic_register(struct side_event_description
*desc
,
189 void (*call_variadic
)(const struct side_event_description
*desc
,
190 const struct side_arg_vec_description
*sav_desc
,
191 const struct side_arg_dynamic_event_struct
*var_struct
,
195 if (!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))
196 return SIDE_ERROR_INVAL
;
197 return _side_tracer_callback_register(desc
, call_variadic
, priv
);
200 int _side_tracer_callback_unregister(struct side_event_description
*desc
,
201 void (*call
)(), void *priv
)
203 struct side_callback
*old_cb
, *new_cb
;
204 const struct side_callback
*cb_pos
;
206 int ret
= SIDE_ERROR_OK
;
210 return SIDE_ERROR_INVAL
;
212 return SIDE_ERROR_EXITING
;
215 pthread_mutex_lock(&side_lock
);
216 cb_pos
= side_tracer_callback_lookup(desc
, call
, priv
);
218 ret
= SIDE_ERROR_NOENT
;
221 old_nr_cb
= *desc
->enabled
& SIDE_EVENT_ENABLED_USER_MASK
;
222 old_cb
= (struct side_callback
*) desc
->callbacks
;
223 if (old_nr_cb
== 1) {
224 new_cb
= (struct side_callback
*) &side_empty_callback
;
226 pos_idx
= cb_pos
- desc
->callbacks
;
227 /* Remove entry at pos_idx. */
228 /* old_nr_cb - 1 (removed cb) + 1 (NULL) */
229 new_cb
= (struct side_callback
*) calloc(old_nr_cb
, sizeof(struct side_callback
));
231 ret
= SIDE_ERROR_NOMEM
;
234 memcpy(new_cb
, old_cb
, pos_idx
);
235 memcpy(&new_cb
[pos_idx
], &old_cb
[pos_idx
+ 1], old_nr_cb
- pos_idx
- 1);
237 side_rcu_assign_pointer(desc
->callbacks
, new_cb
);
238 side_rcu_wait_grace_period(&rcu_gp
);
240 /* Decrement concurrently with kernel setting the top bits. */
241 (void) __atomic_add_fetch(desc
->enabled
, -1, __ATOMIC_RELAXED
);
243 pthread_mutex_unlock(&side_lock
);
247 int side_tracer_callback_unregister(struct side_event_description
*desc
,
248 void (*call
)(const struct side_event_description
*desc
,
249 const struct side_arg_vec_description
*sav_desc
,
253 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
254 return SIDE_ERROR_INVAL
;
255 return _side_tracer_callback_unregister(desc
, call
, priv
);
258 int side_tracer_callback_variadic_unregister(struct side_event_description
*desc
,
259 void (*call_variadic
)(const struct side_event_description
*desc
,
260 const struct side_arg_vec_description
*sav_desc
,
261 const struct side_arg_dynamic_event_struct
*var_struct
,
265 if (!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))
266 return SIDE_ERROR_INVAL
;
267 return _side_tracer_callback_unregister(desc
, call_variadic
, priv
);
270 struct side_events_register_handle
*side_events_register(struct side_event_description
**events
, uint32_t nr_events
)
272 struct side_events_register_handle
*events_handle
= NULL
;
273 struct side_tracer_handle
*tracer_handle
;
279 events_handle
= calloc(1, sizeof(struct side_events_register_handle
));
282 events_handle
->events
= events
;
283 events_handle
->nr_events
= nr_events
;
285 pthread_mutex_lock(&side_lock
);
286 side_list_insert_node_tail(&side_events_list
, &events_handle
->node
);
287 side_list_for_each_entry(tracer_handle
, &side_tracer_list
, node
) {
288 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS
,
289 events
, nr_events
, tracer_handle
->priv
);
291 pthread_mutex_unlock(&side_lock
);
292 //TODO: call event batch register ioctl
293 return events_handle
;
297 void side_event_remove_callbacks(struct side_event_description
*desc
)
299 uint32_t nr_cb
= *desc
->enabled
& SIDE_EVENT_ENABLED_USER_MASK
;
300 struct side_callback
*old_cb
;
304 old_cb
= (struct side_callback
*) desc
->callbacks
;
306 * Setting the state back to 0 cb and empty callbacks out of
307 * caution. This should not matter because instrumentation is
310 (void) __atomic_add_fetch(desc
->enabled
, -nr_cb
, __ATOMIC_RELAXED
);
311 side_rcu_assign_pointer(desc
->callbacks
, &side_empty_callback
);
313 * No need to wait for grace period because instrumentation is
320 * Unregister event handle. At this point, all side events in that
321 * handle should be unreachable.
323 void side_events_unregister(struct side_events_register_handle
*events_handle
)
325 struct side_tracer_handle
*tracer_handle
;
334 pthread_mutex_lock(&side_lock
);
335 side_list_remove_node(&events_handle
->node
);
336 side_list_for_each_entry(tracer_handle
, &side_tracer_list
, node
) {
337 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS
,
338 events_handle
->events
, events_handle
->nr_events
,
339 tracer_handle
->priv
);
341 for (i
= 0; i
< events_handle
->nr_events
; i
++) {
342 struct side_event_description
*event
= events_handle
->events
[i
];
344 /* Skip NULL pointers */
347 side_event_remove_callbacks(event
);
349 pthread_mutex_unlock(&side_lock
);
350 //TODO: call event batch unregister ioctl
354 struct side_tracer_handle
*side_tracer_event_notification_register(
355 void (*cb
)(enum side_tracer_notification notif
,
356 struct side_event_description
**events
, uint32_t nr_events
, void *priv
),
359 struct side_tracer_handle
*tracer_handle
;
360 struct side_events_register_handle
*events_handle
;
366 tracer_handle
= calloc(1, sizeof(struct side_tracer_handle
));
369 pthread_mutex_lock(&side_lock
);
370 tracer_handle
->cb
= cb
;
371 tracer_handle
->priv
= priv
;
372 side_list_insert_node_tail(&side_tracer_list
, &tracer_handle
->node
);
373 side_list_for_each_entry(events_handle
, &side_events_list
, node
) {
374 cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS
,
375 events_handle
->events
, events_handle
->nr_events
, priv
);
377 pthread_mutex_unlock(&side_lock
);
378 return tracer_handle
;
381 void side_tracer_event_notification_unregister(struct side_tracer_handle
*tracer_handle
)
383 struct side_events_register_handle
*events_handle
;
389 pthread_mutex_lock(&side_lock
);
390 side_list_for_each_entry(events_handle
, &side_events_list
, node
) {
391 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS
,
392 events_handle
->events
, events_handle
->nr_events
,
393 tracer_handle
->priv
);
395 side_list_remove_node(&tracer_handle
->node
);
396 pthread_mutex_unlock(&side_lock
);
403 side_rcu_gp_init(&rcu_gp
);
408 * side_exit() is executed from a library destructor. It can be called
409 * explicitly at application exit as well. Concurrent side API use is
410 * not expected at that point.
414 struct side_events_register_handle
*handle
, *tmp
;
418 side_rcu_gp_exit(&rcu_gp
);
419 side_list_for_each_entry_safe(handle
, tmp
, &side_events_list
, node
)
420 side_events_unregister(handle
);