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6841ae81 MD |
1 | // SPDX-License-Identifier: MIT |
2 | /* | |
3 | * Copyright 2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
4 | */ | |
5 | ||
6 | #include <side/trace.h> | |
a3f36db7 MD |
7 | #include <string.h> |
8 | ||
6841ae81 | 9 | #include "tracer.h" |
85b765b8 | 10 | #include "rcu.h" |
b59abc69 | 11 | #include "list.h" |
6841ae81 | 12 | |
054b7b5c | 13 | /* Top 8 bits reserved for kernel tracer use. */ |
f61301bb MD |
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 | |
17 | ||
18 | /* Allow 2^56 tracer references on an event. */ | |
19 | # define SIDE_EVENT_ENABLED_USER_MASK 0x00FFFFFFFFFFFFFFULL | |
20 | #else | |
21 | # define SIDE_EVENT_ENABLED_KERNEL_MASK 0xFF000000UL | |
22 | # define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 0x80000000UL | |
29b3374e | 23 | |
45172226 | 24 | /* Allow 2^24 tracer references on an event. */ |
f61301bb MD |
25 | # define SIDE_EVENT_ENABLED_USER_MASK 0x00FFFFFFUL |
26 | #endif | |
054b7b5c | 27 | |
6e46f5e6 MD |
28 | struct side_events_register_handle { |
29 | struct side_list_node node; | |
30 | struct side_event_description **events; | |
31 | uint32_t nr_events; | |
32 | }; | |
33 | ||
a13c9d2e MD |
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); | |
38 | void *priv; | |
39 | }; | |
40 | ||
a3f36db7 | 41 | static struct side_rcu_gp_state rcu_gp; |
075ceef7 MD |
42 | |
43 | /* | |
44 | * Lazy initialization for early use within library constructors. | |
45 | */ | |
46 | static bool initialized; | |
6e46f5e6 MD |
47 | /* |
48 | * Do not register/unregister any more events after destructor. | |
49 | */ | |
50 | static bool finalized; | |
075ceef7 | 51 | |
1e070341 MD |
52 | /* |
53 | * Recursive mutex to allow tracer callbacks to use the side API. | |
54 | */ | |
55 | static pthread_mutex_t side_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP; | |
a3f36db7 | 56 | |
a13c9d2e MD |
57 | static DEFINE_SIDE_LIST_HEAD(side_events_list); |
58 | static DEFINE_SIDE_LIST_HEAD(side_tracer_list); | |
b59abc69 | 59 | |
a3f36db7 MD |
60 | /* |
61 | * The empty callback has a NULL function callback pointer, which stops | |
62 | * iteration on the array of callbacks immediately. | |
63 | */ | |
8bd36d3b | 64 | const struct side_callback side_empty_callback = { }; |
054b7b5c | 65 | |
6e46f5e6 MD |
66 | void side_init(void) __attribute__((constructor)); |
67 | void side_exit(void) __attribute__((destructor)); | |
68 | ||
9a6ca773 | 69 | void side_call(const struct side_event_description *desc, const struct side_arg_vec *side_arg_vec) |
6841ae81 | 70 | { |
054b7b5c MD |
71 | const struct side_callback *side_cb; |
72 | unsigned int rcu_period; | |
beea6e2e | 73 | uintptr_t enabled; |
054b7b5c | 74 | |
6e46f5e6 MD |
75 | if (side_unlikely(finalized)) |
76 | return; | |
075ceef7 MD |
77 | if (side_unlikely(!initialized)) |
78 | side_init(); | |
6841ae81 MD |
79 | if (side_unlikely(desc->flags & SIDE_EVENT_FLAG_VARIADIC)) { |
80 | printf("ERROR: unexpected variadic event description\n"); | |
81 | abort(); | |
82 | } | |
3b4f86f6 MD |
83 | enabled = __atomic_load_n(desc->enabled, __ATOMIC_RELAXED); |
84 | if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) { | |
dda82f46 | 85 | // TODO: call kernel write. |
6841ae81 | 86 | } |
054b7b5c MD |
87 | rcu_period = side_rcu_read_begin(&rcu_gp); |
88 | for (side_cb = side_rcu_dereference(desc->callbacks); side_cb->u.call != NULL; side_cb++) | |
9a6ca773 | 89 | side_cb->u.call(desc, side_arg_vec, side_cb->priv); |
054b7b5c | 90 | side_rcu_read_end(&rcu_gp, rcu_period); |
6841ae81 MD |
91 | } |
92 | ||
93 | void side_call_variadic(const struct side_event_description *desc, | |
9a6ca773 | 94 | const struct side_arg_vec *side_arg_vec, |
0c7abe2b | 95 | const struct side_arg_dynamic_struct *var_struct) |
6841ae81 | 96 | { |
054b7b5c MD |
97 | const struct side_callback *side_cb; |
98 | unsigned int rcu_period; | |
beea6e2e | 99 | uintptr_t enabled; |
054b7b5c | 100 | |
6e46f5e6 MD |
101 | if (side_unlikely(finalized)) |
102 | return; | |
075ceef7 MD |
103 | if (side_unlikely(!initialized)) |
104 | side_init(); | |
3b4f86f6 MD |
105 | if (side_unlikely(!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))) { |
106 | printf("ERROR: unexpected non-variadic event description\n"); | |
107 | abort(); | |
108 | } | |
109 | enabled = __atomic_load_n(desc->enabled, __ATOMIC_RELAXED); | |
110 | if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) { | |
dda82f46 | 111 | // TODO: call kernel write. |
6841ae81 | 112 | } |
054b7b5c MD |
113 | rcu_period = side_rcu_read_begin(&rcu_gp); |
114 | for (side_cb = side_rcu_dereference(desc->callbacks); side_cb->u.call_variadic != NULL; side_cb++) | |
9a6ca773 | 115 | side_cb->u.call_variadic(desc, side_arg_vec, var_struct, side_cb->priv); |
054b7b5c | 116 | side_rcu_read_end(&rcu_gp, rcu_period); |
6841ae81 | 117 | } |
075ceef7 | 118 | |
a3f36db7 MD |
119 | static |
120 | const struct side_callback *side_tracer_callback_lookup( | |
121 | const struct side_event_description *desc, | |
07e94ffc | 122 | void *call, void *priv) |
a3f36db7 MD |
123 | { |
124 | const struct side_callback *cb; | |
125 | ||
126 | for (cb = desc->callbacks; cb->u.call != NULL; cb++) { | |
07e94ffc | 127 | if ((void *) cb->u.call == call && cb->priv == priv) |
a3f36db7 MD |
128 | return cb; |
129 | } | |
130 | return NULL; | |
131 | } | |
132 | ||
133 | static | |
134 | int _side_tracer_callback_register(struct side_event_description *desc, | |
8bd36d3b | 135 | void *call, void *priv) |
a3f36db7 MD |
136 | { |
137 | struct side_callback *old_cb, *new_cb; | |
138 | int ret = SIDE_ERROR_OK; | |
139 | uint32_t old_nr_cb; | |
140 | ||
141 | if (!call) | |
142 | return SIDE_ERROR_INVAL; | |
6e46f5e6 MD |
143 | if (finalized) |
144 | return SIDE_ERROR_EXITING; | |
a13c9d2e MD |
145 | if (!initialized) |
146 | side_init(); | |
a3f36db7 | 147 | pthread_mutex_lock(&side_lock); |
45172226 MD |
148 | old_nr_cb = desc->nr_callbacks; |
149 | if (old_nr_cb == UINT32_MAX) { | |
a3f36db7 MD |
150 | ret = SIDE_ERROR_INVAL; |
151 | goto unlock; | |
152 | } | |
153 | /* Reject duplicate (call, priv) tuples. */ | |
154 | if (side_tracer_callback_lookup(desc, call, priv)) { | |
155 | ret = SIDE_ERROR_EXIST; | |
156 | goto unlock; | |
157 | } | |
158 | old_cb = (struct side_callback *) desc->callbacks; | |
159 | /* old_nr_cb + 1 (new cb) + 1 (NULL) */ | |
160 | new_cb = (struct side_callback *) calloc(old_nr_cb + 2, sizeof(struct side_callback)); | |
161 | if (!new_cb) { | |
162 | ret = SIDE_ERROR_NOMEM; | |
163 | goto unlock; | |
164 | } | |
165 | memcpy(new_cb, old_cb, old_nr_cb); | |
166 | if (desc->flags & SIDE_EVENT_FLAG_VARIADIC) | |
07e94ffc MD |
167 | new_cb[old_nr_cb].u.call_variadic = |
168 | (side_tracer_callback_variadic_func) call; | |
a3f36db7 | 169 | else |
07e94ffc MD |
170 | new_cb[old_nr_cb].u.call = |
171 | (side_tracer_callback_func) call; | |
a3f36db7 MD |
172 | new_cb[old_nr_cb].priv = priv; |
173 | side_rcu_assign_pointer(desc->callbacks, new_cb); | |
174 | side_rcu_wait_grace_period(&rcu_gp); | |
175 | if (old_nr_cb) | |
176 | free(old_cb); | |
45172226 | 177 | desc->nr_callbacks++; |
a3f36db7 | 178 | /* Increment concurrently with kernel setting the top bits. */ |
45172226 MD |
179 | if (!old_nr_cb) |
180 | (void) __atomic_add_fetch(desc->enabled, 1, __ATOMIC_RELAXED); | |
a3f36db7 MD |
181 | unlock: |
182 | pthread_mutex_unlock(&side_lock); | |
183 | return ret; | |
184 | } | |
185 | ||
186 | int side_tracer_callback_register(struct side_event_description *desc, | |
8bd36d3b | 187 | side_tracer_callback_func call, |
a3f36db7 MD |
188 | void *priv) |
189 | { | |
190 | if (desc->flags & SIDE_EVENT_FLAG_VARIADIC) | |
191 | return SIDE_ERROR_INVAL; | |
07e94ffc | 192 | return _side_tracer_callback_register(desc, (void *) call, priv); |
a3f36db7 MD |
193 | } |
194 | ||
195 | int side_tracer_callback_variadic_register(struct side_event_description *desc, | |
8bd36d3b | 196 | side_tracer_callback_variadic_func call_variadic, |
a3f36db7 MD |
197 | void *priv) |
198 | { | |
199 | if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC)) | |
200 | return SIDE_ERROR_INVAL; | |
07e94ffc | 201 | return _side_tracer_callback_register(desc, (void *) call_variadic, priv); |
a3f36db7 MD |
202 | } |
203 | ||
204 | int _side_tracer_callback_unregister(struct side_event_description *desc, | |
8bd36d3b | 205 | void *call, void *priv) |
a3f36db7 MD |
206 | { |
207 | struct side_callback *old_cb, *new_cb; | |
208 | const struct side_callback *cb_pos; | |
209 | uint32_t pos_idx; | |
210 | int ret = SIDE_ERROR_OK; | |
211 | uint32_t old_nr_cb; | |
212 | ||
213 | if (!call) | |
214 | return SIDE_ERROR_INVAL; | |
6e46f5e6 MD |
215 | if (finalized) |
216 | return SIDE_ERROR_EXITING; | |
a13c9d2e MD |
217 | if (!initialized) |
218 | side_init(); | |
a3f36db7 | 219 | pthread_mutex_lock(&side_lock); |
a3f36db7 MD |
220 | cb_pos = side_tracer_callback_lookup(desc, call, priv); |
221 | if (!cb_pos) { | |
222 | ret = SIDE_ERROR_NOENT; | |
223 | goto unlock; | |
224 | } | |
45172226 | 225 | old_nr_cb = desc->nr_callbacks; |
9a83b759 | 226 | old_cb = (struct side_callback *) desc->callbacks; |
a3f36db7 MD |
227 | if (old_nr_cb == 1) { |
228 | new_cb = (struct side_callback *) &side_empty_callback; | |
229 | } else { | |
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)); | |
234 | if (!new_cb) { | |
235 | ret = SIDE_ERROR_NOMEM; | |
236 | goto unlock; | |
237 | } | |
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); | |
240 | } | |
241 | side_rcu_assign_pointer(desc->callbacks, new_cb); | |
242 | side_rcu_wait_grace_period(&rcu_gp); | |
243 | free(old_cb); | |
45172226 | 244 | desc->nr_callbacks--; |
a3f36db7 | 245 | /* Decrement concurrently with kernel setting the top bits. */ |
45172226 MD |
246 | if (old_nr_cb == 1) |
247 | (void) __atomic_add_fetch(desc->enabled, -1, __ATOMIC_RELAXED); | |
a3f36db7 MD |
248 | unlock: |
249 | pthread_mutex_unlock(&side_lock); | |
250 | return ret; | |
251 | } | |
252 | ||
253 | int side_tracer_callback_unregister(struct side_event_description *desc, | |
8bd36d3b | 254 | side_tracer_callback_func call, |
a3f36db7 MD |
255 | void *priv) |
256 | { | |
257 | if (desc->flags & SIDE_EVENT_FLAG_VARIADIC) | |
258 | return SIDE_ERROR_INVAL; | |
07e94ffc | 259 | return _side_tracer_callback_unregister(desc, (void *) call, priv); |
a3f36db7 MD |
260 | } |
261 | ||
262 | int side_tracer_callback_variadic_unregister(struct side_event_description *desc, | |
8bd36d3b | 263 | side_tracer_callback_variadic_func call_variadic, |
a3f36db7 MD |
264 | void *priv) |
265 | { | |
266 | if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC)) | |
267 | return SIDE_ERROR_INVAL; | |
07e94ffc | 268 | return _side_tracer_callback_unregister(desc, (void *) call_variadic, priv); |
a3f36db7 MD |
269 | } |
270 | ||
6e46f5e6 MD |
271 | struct side_events_register_handle *side_events_register(struct side_event_description **events, uint32_t nr_events) |
272 | { | |
a13c9d2e MD |
273 | struct side_events_register_handle *events_handle = NULL; |
274 | struct side_tracer_handle *tracer_handle; | |
6e46f5e6 MD |
275 | |
276 | if (finalized) | |
277 | return NULL; | |
a13c9d2e MD |
278 | if (!initialized) |
279 | side_init(); | |
07e94ffc MD |
280 | events_handle = (struct side_events_register_handle *) |
281 | calloc(1, sizeof(struct side_events_register_handle)); | |
a13c9d2e | 282 | if (!events_handle) |
6e46f5e6 | 283 | return NULL; |
a13c9d2e MD |
284 | events_handle->events = events; |
285 | events_handle->nr_events = nr_events; | |
286 | ||
6e46f5e6 | 287 | pthread_mutex_lock(&side_lock); |
a13c9d2e MD |
288 | side_list_insert_node_tail(&side_events_list, &events_handle->node); |
289 | side_list_for_each_entry(tracer_handle, &side_tracer_list, node) { | |
290 | tracer_handle->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS, | |
291 | events, nr_events, tracer_handle->priv); | |
292 | } | |
6e46f5e6 MD |
293 | pthread_mutex_unlock(&side_lock); |
294 | //TODO: call event batch register ioctl | |
a13c9d2e | 295 | return events_handle; |
6e46f5e6 MD |
296 | } |
297 | ||
a3f36db7 | 298 | static |
6e46f5e6 MD |
299 | void side_event_remove_callbacks(struct side_event_description *desc) |
300 | { | |
ea0d2bea | 301 | uint32_t nr_cb = desc->nr_callbacks; |
6e46f5e6 MD |
302 | struct side_callback *old_cb; |
303 | ||
304 | if (!nr_cb) | |
305 | return; | |
306 | old_cb = (struct side_callback *) desc->callbacks; | |
ea0d2bea | 307 | (void) __atomic_add_fetch(desc->enabled, -1, __ATOMIC_RELAXED); |
6e46f5e6 MD |
308 | /* |
309 | * Setting the state back to 0 cb and empty callbacks out of | |
310 | * caution. This should not matter because instrumentation is | |
311 | * unreachable. | |
312 | */ | |
45172226 | 313 | desc->nr_callbacks = 0; |
6e46f5e6 MD |
314 | side_rcu_assign_pointer(desc->callbacks, &side_empty_callback); |
315 | /* | |
316 | * No need to wait for grace period because instrumentation is | |
317 | * unreachable. | |
318 | */ | |
319 | free(old_cb); | |
320 | } | |
321 | ||
322 | /* | |
323 | * Unregister event handle. At this point, all side events in that | |
324 | * handle should be unreachable. | |
325 | */ | |
a13c9d2e | 326 | void side_events_unregister(struct side_events_register_handle *events_handle) |
6e46f5e6 | 327 | { |
a13c9d2e | 328 | struct side_tracer_handle *tracer_handle; |
6e46f5e6 MD |
329 | uint32_t i; |
330 | ||
314c22c3 MD |
331 | if (!events_handle) |
332 | return; | |
6e46f5e6 MD |
333 | if (finalized) |
334 | return; | |
a13c9d2e MD |
335 | if (!initialized) |
336 | side_init(); | |
6e46f5e6 | 337 | pthread_mutex_lock(&side_lock); |
a13c9d2e MD |
338 | side_list_remove_node(&events_handle->node); |
339 | side_list_for_each_entry(tracer_handle, &side_tracer_list, node) { | |
340 | tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS, | |
341 | events_handle->events, events_handle->nr_events, | |
342 | tracer_handle->priv); | |
343 | } | |
344 | for (i = 0; i < events_handle->nr_events; i++) { | |
345 | struct side_event_description *event = events_handle->events[i]; | |
6e46f5e6 MD |
346 | |
347 | /* Skip NULL pointers */ | |
348 | if (!event) | |
349 | continue; | |
350 | side_event_remove_callbacks(event); | |
351 | } | |
352 | pthread_mutex_unlock(&side_lock); | |
353 | //TODO: call event batch unregister ioctl | |
a13c9d2e MD |
354 | free(events_handle); |
355 | } | |
356 | ||
357 | struct side_tracer_handle *side_tracer_event_notification_register( | |
358 | void (*cb)(enum side_tracer_notification notif, | |
359 | struct side_event_description **events, uint32_t nr_events, void *priv), | |
360 | void *priv) | |
361 | { | |
362 | struct side_tracer_handle *tracer_handle; | |
363 | struct side_events_register_handle *events_handle; | |
364 | ||
365 | if (finalized) | |
366 | return NULL; | |
367 | if (!initialized) | |
368 | side_init(); | |
07e94ffc MD |
369 | tracer_handle = (struct side_tracer_handle *) |
370 | calloc(1, sizeof(struct side_tracer_handle)); | |
a13c9d2e MD |
371 | if (!tracer_handle) |
372 | return NULL; | |
373 | pthread_mutex_lock(&side_lock); | |
374 | tracer_handle->cb = cb; | |
375 | tracer_handle->priv = priv; | |
376 | side_list_insert_node_tail(&side_tracer_list, &tracer_handle->node); | |
377 | side_list_for_each_entry(events_handle, &side_events_list, node) { | |
378 | cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS, | |
379 | events_handle->events, events_handle->nr_events, priv); | |
380 | } | |
381 | pthread_mutex_unlock(&side_lock); | |
382 | return tracer_handle; | |
383 | } | |
384 | ||
385 | void side_tracer_event_notification_unregister(struct side_tracer_handle *tracer_handle) | |
386 | { | |
387 | struct side_events_register_handle *events_handle; | |
388 | ||
389 | if (finalized) | |
390 | return; | |
391 | if (!initialized) | |
392 | side_init(); | |
393 | pthread_mutex_lock(&side_lock); | |
394 | side_list_for_each_entry(events_handle, &side_events_list, node) { | |
395 | tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS, | |
396 | events_handle->events, events_handle->nr_events, | |
397 | tracer_handle->priv); | |
398 | } | |
399 | side_list_remove_node(&tracer_handle->node); | |
400 | pthread_mutex_unlock(&side_lock); | |
6e46f5e6 MD |
401 | } |
402 | ||
075ceef7 MD |
403 | void side_init(void) |
404 | { | |
405 | if (initialized) | |
406 | return; | |
054b7b5c | 407 | side_rcu_gp_init(&rcu_gp); |
075ceef7 MD |
408 | initialized = true; |
409 | } | |
6e46f5e6 | 410 | |
aa584c16 MD |
411 | /* |
412 | * side_exit() is executed from a library destructor. It can be called | |
413 | * explicitly at application exit as well. Concurrent side API use is | |
414 | * not expected at that point. | |
415 | */ | |
6e46f5e6 MD |
416 | void side_exit(void) |
417 | { | |
418 | struct side_events_register_handle *handle, *tmp; | |
419 | ||
420 | if (finalized) | |
421 | return; | |
a13c9d2e | 422 | side_list_for_each_entry_safe(handle, tmp, &side_events_list, node) |
6e46f5e6 | 423 | side_events_unregister(handle); |
64d29894 | 424 | side_rcu_gp_exit(&rcu_gp); |
6e46f5e6 MD |
425 | finalized = true; |
426 | } |