2 * SPDX-License-Identifier: LGPL-2.1-only
4 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
6 * LTTng UST trace/channel/event context management.
10 #include <lttng/ust-events.h>
11 #include <lttng/ust-tracer.h>
12 #include <ust-context-provider.h>
13 #include <lttng/urcu/pointer.h>
14 #include <lttng/urcu/urcu-ust.h>
15 #include <usterr-signal-safe.h>
16 #include <ust-helper.h>
21 #include "tracepoint-internal.h"
23 #include "context-internal.h"
26 * The filter implementation requires that two consecutive "get" for the
27 * same context performed by the same thread return the same result.
30 int lttng_find_context(struct lttng_ust_ctx
*ctx
, const char *name
)
35 if (strncmp(name
, "$ctx.", strlen("$ctx.")) == 0) {
36 subname
= name
+ strlen("$ctx.");
40 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
41 /* Skip allocated (but non-initialized) contexts */
42 if (!ctx
->fields
[i
]->event_field
->name
)
44 if (!strcmp(ctx
->fields
[i
]->event_field
->name
, subname
))
50 int lttng_get_context_index(struct lttng_ust_ctx
*ctx
, const char *name
)
57 if (strncmp(name
, "$ctx.", strlen("$ctx.")) == 0) {
58 subname
= name
+ strlen("$ctx.");
62 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
63 /* Skip allocated (but non-initialized) contexts */
64 if (!ctx
->fields
[i
]->event_field
->name
)
66 if (!strcmp(ctx
->fields
[i
]->event_field
->name
, subname
))
72 static int lttng_find_context_provider(struct lttng_ust_ctx
*ctx
, const char *name
)
76 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
77 /* Skip allocated (but non-initialized) contexts */
78 if (!ctx
->fields
[i
]->event_field
->name
)
80 if (!strncmp(ctx
->fields
[i
]->event_field
->name
, name
,
88 * Note: as we append context information, the pointer location may change.
89 * lttng_add_context leaves the new last context initialized to NULL.
92 int lttng_add_context(struct lttng_ust_ctx
**ctx_p
)
94 struct lttng_ust_ctx
*ctx
;
97 *ctx_p
= zmalloc(sizeof(struct lttng_ust_ctx
));
100 (*ctx_p
)->struct_size
= sizeof(struct lttng_ust_ctx
);
101 (*ctx_p
)->largest_align
= 1;
104 if (ctx
->nr_fields
+ 1 > ctx
->allocated_fields
) {
105 struct lttng_ust_ctx_field
**new_fields
;
107 ctx
->allocated_fields
= max_t(size_t, 1, 2 * ctx
->allocated_fields
);
108 new_fields
= zmalloc(ctx
->allocated_fields
* sizeof(*new_fields
));
113 memcpy(new_fields
, ctx
->fields
, sizeof(*ctx
->fields
) * ctx
->nr_fields
);
115 ctx
->fields
= new_fields
;
121 struct lttng_ust_ctx_field
*lttng_append_context(struct lttng_ust_ctx
**ctx_p
)
123 struct lttng_ust_ctx_field
*field
;
126 field
= zmalloc(sizeof(struct lttng_ust_ctx_field
));
128 goto error_alloc_field
;
129 field
->struct_size
= sizeof(struct lttng_ust_ctx_field
);
130 field
->event_field
= zmalloc(sizeof(struct lttng_ust_event_field
));
131 if (!field
->event_field
)
132 goto error_alloc_event_field
;
133 field
->event_field
->struct_size
= sizeof(struct lttng_ust_event_field
);
135 ret
= lttng_add_context(ctx_p
);
137 goto error_add_context
;
138 (*ctx_p
)->fields
[(*ctx_p
)->nr_fields
- 1] = field
;
142 free(field
->event_field
);
143 error_alloc_event_field
:
150 * Takes ownership of @f on success.
152 int lttng_context_add_rcu(struct lttng_ust_ctx
**ctx_p
,
153 struct lttng_ust_ctx_field
*f
)
155 struct lttng_ust_ctx
*old_ctx
= *ctx_p
, *new_ctx
= NULL
;
156 struct lttng_ust_ctx_field
**new_fields
= NULL
;
160 new_ctx
= zmalloc(sizeof(struct lttng_ust_ctx
));
163 new_ctx
->struct_size
= sizeof(struct lttng_ust_ctx
);
165 new_fields
= zmalloc(new_ctx
->allocated_fields
* sizeof(*new_fields
));
171 memcpy(new_fields
, old_ctx
->fields
,
172 sizeof(*old_ctx
->fields
) * old_ctx
->nr_fields
);
173 new_ctx
->fields
= new_fields
;
175 ret
= lttng_add_context(&new_ctx
);
181 /* Taking ownership of f. */
182 (*ctx_p
)->fields
[(*ctx_p
)->nr_fields
- 1] = f
;
183 lttng_context_update(new_ctx
);
184 lttng_ust_rcu_assign_pointer(*ctx_p
, new_ctx
);
185 lttng_ust_urcu_synchronize_rcu();
187 free(old_ctx
->fields
);
193 static size_t get_type_max_align(struct lttng_ust_type_common
*type
)
195 switch (type
->type
) {
196 case lttng_ust_type_integer
:
197 return lttng_ust_get_type_integer(type
)->alignment
;
198 case lttng_ust_type_string
:
200 case lttng_ust_type_dynamic
:
202 case lttng_ust_type_enum
:
203 return get_type_max_align(lttng_ust_get_type_enum(type
)->container_type
);
204 case lttng_ust_type_array
:
205 return max_t(size_t, get_type_max_align(lttng_ust_get_type_array(type
)->elem_type
),
206 lttng_ust_get_type_array(type
)->alignment
);
207 case lttng_ust_type_sequence
:
208 return max_t(size_t, get_type_max_align(lttng_ust_get_type_sequence(type
)->elem_type
),
209 lttng_ust_get_type_sequence(type
)->alignment
);
210 case lttng_ust_type_struct
:
213 size_t field_align
= 0;
214 struct lttng_ust_type_struct
*struct_type
= lttng_ust_get_type_struct(type
);
216 for (i
= 0; i
< struct_type
->nr_fields
; i
++) {
217 field_align
= max_t(size_t,
218 get_type_max_align(struct_type
->fields
[i
]->type
),
230 * lttng_context_update() should be called at least once between context
231 * modification and trace start.
233 void lttng_context_update(struct lttng_ust_ctx
*ctx
)
236 size_t largest_align
= 8; /* in bits */
238 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
239 size_t field_align
= 8;
241 field_align
= get_type_max_align(ctx
->fields
[i
]->event_field
->type
);
242 largest_align
= max_t(size_t, largest_align
, field_align
);
244 ctx
->largest_align
= largest_align
>> 3; /* bits to bytes */
248 * Remove last context field.
250 void lttng_remove_context_field(struct lttng_ust_ctx
**ctx_p
,
251 struct lttng_ust_ctx_field
*field
)
253 struct lttng_ust_ctx
*ctx
;
257 assert(ctx
->fields
[ctx
->nr_fields
] == field
);
258 lttng_ust_destroy_type(field
->event_field
->type
);
259 free((char *) field
->event_field
->name
);
260 free(field
->event_field
);
262 ctx
->fields
[ctx
->nr_fields
] = NULL
;
265 void lttng_destroy_context(struct lttng_ust_ctx
*ctx
)
271 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
272 if (ctx
->fields
[i
]->destroy
)
273 ctx
->fields
[i
]->destroy(ctx
->fields
[i
]);
274 lttng_ust_destroy_type(ctx
->fields
[i
]->event_field
->type
);
275 free((char *) ctx
->fields
[i
]->event_field
->name
);
276 free(ctx
->fields
[i
]->event_field
);
277 free(ctx
->fields
[i
]);
284 * Can be safely performed concurrently with tracing using the struct
285 * lttng_ctx. Using RCU update. Needs to match RCU read-side handling of
288 * This does not allow adding, removing, or changing typing of the
289 * contexts, since this needs to stay invariant for metadata. However,
290 * it allows updating the handlers associated with all contexts matching
291 * a provider (by name) while tracing is using it, in a way that ensures
292 * a single RCU read-side critical section see either all old, or all
295 int lttng_ust_context_set_provider_rcu(struct lttng_ust_ctx
**_ctx
,
297 size_t (*get_size
)(struct lttng_ust_ctx_field
*field
, size_t offset
),
298 void (*record
)(struct lttng_ust_ctx_field
*field
,
299 struct lttng_ust_lib_ring_buffer_ctx
*ctx
,
300 struct lttng_ust_channel_buffer
*chan
),
301 void (*get_value
)(struct lttng_ust_ctx_field
*field
,
302 struct lttng_ust_ctx_value
*value
))
305 struct lttng_ust_ctx
*ctx
= *_ctx
, *new_ctx
;
306 struct lttng_ust_ctx_field
**new_fields
;
308 if (!ctx
|| !lttng_find_context_provider(ctx
, name
))
311 * We have at least one instance of context for the provider.
313 new_ctx
= zmalloc(sizeof(*new_ctx
));
316 new_ctx
->struct_size
= sizeof(*new_ctx
);
318 new_fields
= zmalloc(sizeof(*new_fields
) * ctx
->allocated_fields
);
324 memcpy(new_fields
, ctx
->fields
,
325 sizeof(*new_fields
) * ctx
->allocated_fields
);
326 for (i
= 0; i
< ctx
->nr_fields
; i
++) {
327 if (strncmp(new_fields
[i
]->event_field
->name
,
328 name
, strlen(name
)) != 0)
330 new_fields
[i
]->get_size
= get_size
;
331 new_fields
[i
]->record
= record
;
332 new_fields
[i
]->get_value
= get_value
;
334 new_ctx
->fields
= new_fields
;
335 lttng_ust_rcu_assign_pointer(*_ctx
, new_ctx
);
336 lttng_ust_urcu_synchronize_rcu();
346 int lttng_context_init_all(struct lttng_ust_ctx
**ctx
)
350 ret
= lttng_add_pthread_id_to_ctx(ctx
);
352 WARN("Cannot add context lttng_add_pthread_id_to_ctx");
355 ret
= lttng_add_vtid_to_ctx(ctx
);
357 WARN("Cannot add context lttng_add_vtid_to_ctx");
360 ret
= lttng_add_vpid_to_ctx(ctx
);
362 WARN("Cannot add context lttng_add_vpid_to_ctx");
365 ret
= lttng_add_procname_to_ctx(ctx
);
367 WARN("Cannot add context lttng_add_procname_to_ctx");
370 ret
= lttng_add_cpu_id_to_ctx(ctx
);
372 WARN("Cannot add context lttng_add_cpu_id_to_ctx");
375 ret
= lttng_add_cgroup_ns_to_ctx(ctx
);
377 WARN("Cannot add context lttng_add_cgroup_ns_to_ctx");
380 ret
= lttng_add_ipc_ns_to_ctx(ctx
);
382 WARN("Cannot add context lttng_add_ipc_ns_to_ctx");
385 ret
= lttng_add_mnt_ns_to_ctx(ctx
);
387 WARN("Cannot add context lttng_add_mnt_ns_to_ctx");
390 ret
= lttng_add_net_ns_to_ctx(ctx
);
392 WARN("Cannot add context lttng_add_net_ns_to_ctx");
395 ret
= lttng_add_pid_ns_to_ctx(ctx
);
397 WARN("Cannot add context lttng_add_pid_ns_to_ctx");
400 ret
= lttng_add_time_ns_to_ctx(ctx
);
402 WARN("Cannot add context lttng_add_time_ns_to_ctx");
405 ret
= lttng_add_user_ns_to_ctx(ctx
);
407 WARN("Cannot add context lttng_add_user_ns_to_ctx");
410 ret
= lttng_add_uts_ns_to_ctx(ctx
);
412 WARN("Cannot add context lttng_add_uts_ns_to_ctx");
415 ret
= lttng_add_vuid_to_ctx(ctx
);
417 WARN("Cannot add context lttng_add_vuid_to_ctx");
420 ret
= lttng_add_veuid_to_ctx(ctx
);
422 WARN("Cannot add context lttng_add_veuid_to_ctx");
425 ret
= lttng_add_vsuid_to_ctx(ctx
);
427 WARN("Cannot add context lttng_add_vsuid_to_ctx");
430 ret
= lttng_add_vgid_to_ctx(ctx
);
432 WARN("Cannot add context lttng_add_vgid_to_ctx");
435 ret
= lttng_add_vegid_to_ctx(ctx
);
437 WARN("Cannot add context lttng_add_vegid_to_ctx");
440 ret
= lttng_add_vsgid_to_ctx(ctx
);
442 WARN("Cannot add context lttng_add_vsgid_to_ctx");
445 lttng_context_update(*ctx
);
449 lttng_destroy_context(*ctx
);