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 static struct side_rcu_gp_state rcu_gp
;
44 * Lazy initialization for early use within library constructors.
46 static bool initialized
;
48 * Do not register/unregister any more events after destructor.
50 static bool finalized
;
52 static pthread_mutex_t side_lock
= PTHREAD_MUTEX_INITIALIZER
;
54 static DEFINE_SIDE_LIST_HEAD(side_events_list
);
55 static DEFINE_SIDE_LIST_HEAD(side_tracer_list
);
58 * The empty callback has a NULL function callback pointer, which stops
59 * iteration on the array of callbacks immediately.
61 const struct side_callback side_empty_callback
;
63 void side_init(void) __attribute__((constructor
));
64 void side_exit(void) __attribute__((destructor
));
66 void side_call(const struct side_event_description
*desc
, const struct side_arg_vec_description
*sav_desc
)
68 const struct side_callback
*side_cb
;
69 unsigned int rcu_period
;
72 if (side_unlikely(finalized
))
74 if (side_unlikely(!initialized
))
76 if (side_unlikely(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)) {
77 printf("ERROR: unexpected variadic event description\n");
80 enabled
= __atomic_load_n(desc
->enabled
, __ATOMIC_RELAXED
);
81 if (side_unlikely(enabled
& SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK
)) {
82 // TODO: call kernel write.
84 rcu_period
= side_rcu_read_begin(&rcu_gp
);
85 for (side_cb
= side_rcu_dereference(desc
->callbacks
); side_cb
->u
.call
!= NULL
; side_cb
++)
86 side_cb
->u
.call(desc
, sav_desc
, side_cb
->priv
);
87 side_rcu_read_end(&rcu_gp
, rcu_period
);
90 void side_call_variadic(const struct side_event_description
*desc
,
91 const struct side_arg_vec_description
*sav_desc
,
92 const struct side_arg_dynamic_event_struct
*var_struct
)
94 const struct side_callback
*side_cb
;
95 unsigned int rcu_period
;
98 if (side_unlikely(finalized
))
100 if (side_unlikely(!initialized
))
102 if (side_unlikely(!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))) {
103 printf("ERROR: unexpected non-variadic event description\n");
106 enabled
= __atomic_load_n(desc
->enabled
, __ATOMIC_RELAXED
);
107 if (side_unlikely(enabled
& SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK
)) {
108 // TODO: call kernel write.
110 rcu_period
= side_rcu_read_begin(&rcu_gp
);
111 for (side_cb
= side_rcu_dereference(desc
->callbacks
); side_cb
->u
.call_variadic
!= NULL
; side_cb
++)
112 side_cb
->u
.call_variadic(desc
, sav_desc
, var_struct
, side_cb
->priv
);
113 side_rcu_read_end(&rcu_gp
, rcu_period
);
117 const struct side_callback
*side_tracer_callback_lookup(
118 const struct side_event_description
*desc
,
119 void (*call
)(), void *priv
)
121 const struct side_callback
*cb
;
123 for (cb
= desc
->callbacks
; cb
->u
.call
!= NULL
; cb
++) {
124 if (cb
->u
.call
== call
&& cb
->priv
== priv
)
131 int _side_tracer_callback_register(struct side_event_description
*desc
,
132 void (*call
)(), void *priv
)
134 struct side_callback
*old_cb
, *new_cb
;
135 int ret
= SIDE_ERROR_OK
;
139 return SIDE_ERROR_INVAL
;
141 return SIDE_ERROR_EXITING
;
144 pthread_mutex_lock(&side_lock
);
145 old_nr_cb
= desc
->nr_callbacks
;
146 if (old_nr_cb
== UINT32_MAX
) {
147 ret
= SIDE_ERROR_INVAL
;
150 /* Reject duplicate (call, priv) tuples. */
151 if (side_tracer_callback_lookup(desc
, call
, priv
)) {
152 ret
= SIDE_ERROR_EXIST
;
155 old_cb
= (struct side_callback
*) desc
->callbacks
;
156 /* old_nr_cb + 1 (new cb) + 1 (NULL) */
157 new_cb
= (struct side_callback
*) calloc(old_nr_cb
+ 2, sizeof(struct side_callback
));
159 ret
= SIDE_ERROR_NOMEM
;
162 memcpy(new_cb
, old_cb
, old_nr_cb
);
163 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
164 new_cb
[old_nr_cb
].u
.call_variadic
= call
;
166 new_cb
[old_nr_cb
].u
.call
= call
;
167 new_cb
[old_nr_cb
].priv
= priv
;
168 side_rcu_assign_pointer(desc
->callbacks
, new_cb
);
169 side_rcu_wait_grace_period(&rcu_gp
);
172 desc
->nr_callbacks
++;
173 /* Increment concurrently with kernel setting the top bits. */
175 (void) __atomic_add_fetch(desc
->enabled
, 1, __ATOMIC_RELAXED
);
177 pthread_mutex_unlock(&side_lock
);
181 int side_tracer_callback_register(struct side_event_description
*desc
,
182 void (*call
)(const struct side_event_description
*desc
,
183 const struct side_arg_vec_description
*sav_desc
,
187 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
188 return SIDE_ERROR_INVAL
;
189 return _side_tracer_callback_register(desc
, call
, priv
);
192 int side_tracer_callback_variadic_register(struct side_event_description
*desc
,
193 void (*call_variadic
)(const struct side_event_description
*desc
,
194 const struct side_arg_vec_description
*sav_desc
,
195 const struct side_arg_dynamic_event_struct
*var_struct
,
199 if (!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))
200 return SIDE_ERROR_INVAL
;
201 return _side_tracer_callback_register(desc
, call_variadic
, priv
);
204 int _side_tracer_callback_unregister(struct side_event_description
*desc
,
205 void (*call
)(), void *priv
)
207 struct side_callback
*old_cb
, *new_cb
;
208 const struct side_callback
*cb_pos
;
210 int ret
= SIDE_ERROR_OK
;
214 return SIDE_ERROR_INVAL
;
216 return SIDE_ERROR_EXITING
;
219 pthread_mutex_lock(&side_lock
);
220 cb_pos
= side_tracer_callback_lookup(desc
, call
, priv
);
222 ret
= SIDE_ERROR_NOENT
;
225 old_nr_cb
= desc
->nr_callbacks
;
226 old_cb
= (struct side_callback
*) desc
->callbacks
;
227 if (old_nr_cb
== 1) {
228 new_cb
= (struct side_callback
*) &side_empty_callback
;
230 pos_idx
= cb_pos
- desc
->callbacks
;
231 /* Remove entry at pos_idx. */
232 /* old_nr_cb - 1 (removed cb) + 1 (NULL) */
233 new_cb
= (struct side_callback
*) calloc(old_nr_cb
, sizeof(struct side_callback
));
235 ret
= SIDE_ERROR_NOMEM
;
238 memcpy(new_cb
, old_cb
, pos_idx
);
239 memcpy(&new_cb
[pos_idx
], &old_cb
[pos_idx
+ 1], old_nr_cb
- pos_idx
- 1);
241 side_rcu_assign_pointer(desc
->callbacks
, new_cb
);
242 side_rcu_wait_grace_period(&rcu_gp
);
244 desc
->nr_callbacks
--;
245 /* Decrement concurrently with kernel setting the top bits. */
247 (void) __atomic_add_fetch(desc
->enabled
, -1, __ATOMIC_RELAXED
);
249 pthread_mutex_unlock(&side_lock
);
253 int side_tracer_callback_unregister(struct side_event_description
*desc
,
254 void (*call
)(const struct side_event_description
*desc
,
255 const struct side_arg_vec_description
*sav_desc
,
259 if (desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
)
260 return SIDE_ERROR_INVAL
;
261 return _side_tracer_callback_unregister(desc
, call
, priv
);
264 int side_tracer_callback_variadic_unregister(struct side_event_description
*desc
,
265 void (*call_variadic
)(const struct side_event_description
*desc
,
266 const struct side_arg_vec_description
*sav_desc
,
267 const struct side_arg_dynamic_event_struct
*var_struct
,
271 if (!(desc
->flags
& SIDE_EVENT_FLAG_VARIADIC
))
272 return SIDE_ERROR_INVAL
;
273 return _side_tracer_callback_unregister(desc
, call_variadic
, priv
);
276 struct side_events_register_handle
*side_events_register(struct side_event_description
**events
, uint32_t nr_events
)
278 struct side_events_register_handle
*events_handle
= NULL
;
279 struct side_tracer_handle
*tracer_handle
;
285 events_handle
= calloc(1, sizeof(struct side_events_register_handle
));
288 events_handle
->events
= events
;
289 events_handle
->nr_events
= nr_events
;
291 pthread_mutex_lock(&side_lock
);
292 side_list_insert_node_tail(&side_events_list
, &events_handle
->node
);
293 side_list_for_each_entry(tracer_handle
, &side_tracer_list
, node
) {
294 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS
,
295 events
, nr_events
, tracer_handle
->priv
);
297 pthread_mutex_unlock(&side_lock
);
298 //TODO: call event batch register ioctl
299 return events_handle
;
303 void side_event_remove_callbacks(struct side_event_description
*desc
)
305 uint32_t nr_cb
= desc
->nr_callbacks
;
306 struct side_callback
*old_cb
;
310 old_cb
= (struct side_callback
*) desc
->callbacks
;
311 (void) __atomic_add_fetch(desc
->enabled
, -1, __ATOMIC_RELAXED
);
313 * Setting the state back to 0 cb and empty callbacks out of
314 * caution. This should not matter because instrumentation is
317 desc
->nr_callbacks
= 0;
318 side_rcu_assign_pointer(desc
->callbacks
, &side_empty_callback
);
320 * No need to wait for grace period because instrumentation is
327 * Unregister event handle. At this point, all side events in that
328 * handle should be unreachable.
330 void side_events_unregister(struct side_events_register_handle
*events_handle
)
332 struct side_tracer_handle
*tracer_handle
;
341 pthread_mutex_lock(&side_lock
);
342 side_list_remove_node(&events_handle
->node
);
343 side_list_for_each_entry(tracer_handle
, &side_tracer_list
, node
) {
344 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS
,
345 events_handle
->events
, events_handle
->nr_events
,
346 tracer_handle
->priv
);
348 for (i
= 0; i
< events_handle
->nr_events
; i
++) {
349 struct side_event_description
*event
= events_handle
->events
[i
];
351 /* Skip NULL pointers */
354 side_event_remove_callbacks(event
);
356 pthread_mutex_unlock(&side_lock
);
357 //TODO: call event batch unregister ioctl
361 struct side_tracer_handle
*side_tracer_event_notification_register(
362 void (*cb
)(enum side_tracer_notification notif
,
363 struct side_event_description
**events
, uint32_t nr_events
, void *priv
),
366 struct side_tracer_handle
*tracer_handle
;
367 struct side_events_register_handle
*events_handle
;
373 tracer_handle
= calloc(1, sizeof(struct side_tracer_handle
));
376 pthread_mutex_lock(&side_lock
);
377 tracer_handle
->cb
= cb
;
378 tracer_handle
->priv
= priv
;
379 side_list_insert_node_tail(&side_tracer_list
, &tracer_handle
->node
);
380 side_list_for_each_entry(events_handle
, &side_events_list
, node
) {
381 cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS
,
382 events_handle
->events
, events_handle
->nr_events
, priv
);
384 pthread_mutex_unlock(&side_lock
);
385 return tracer_handle
;
388 void side_tracer_event_notification_unregister(struct side_tracer_handle
*tracer_handle
)
390 struct side_events_register_handle
*events_handle
;
396 pthread_mutex_lock(&side_lock
);
397 side_list_for_each_entry(events_handle
, &side_events_list
, node
) {
398 tracer_handle
->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS
,
399 events_handle
->events
, events_handle
->nr_events
,
400 tracer_handle
->priv
);
402 side_list_remove_node(&tracer_handle
->node
);
403 pthread_mutex_unlock(&side_lock
);
410 side_rcu_gp_init(&rcu_gp
);
415 * side_exit() is executed from a library destructor. It can be called
416 * explicitly at application exit as well. Concurrent side API use is
417 * not expected at that point.
421 struct side_events_register_handle
*handle
, *tmp
;
425 side_rcu_gp_exit(&rcu_gp
);
426 side_list_for_each_entry_safe(handle
, tmp
, &side_events_list
, node
)
427 side_events_unregister(handle
);