2 * SPDX-License-Identifier: LGPL-2.1-only
4 * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
13 #include <lttng/ust-endian.h>
14 #include <usterr-signal-safe.h>
15 #include <urcu/rculist.h>
17 #include "lttng-tracer-core.h"
18 #include "ust-events-internal.h"
19 #include "../libmsgpack/msgpack.h"
20 #include "lttng-bytecode.h"
21 #include "ust-share.h"
24 * We want this write to be atomic AND non-blocking, meaning that we
25 * want to write either everything OR nothing.
26 * According to `pipe(7)`, writes that are less than `PIPE_BUF` bytes must be
27 * atomic, so we bound the capture buffer size to the `PIPE_BUF` minus the size
28 * of the notification struct we are sending alongside the capture buffer.
30 #define CAPTURE_BUFFER_SIZE \
31 (PIPE_BUF - sizeof(struct lttng_ust_abi_event_notifier_notification) - 1)
33 struct lttng_event_notifier_notification
{
35 uint64_t event_notifier_token
;
36 uint8_t capture_buf
[CAPTURE_BUFFER_SIZE
];
37 struct lttng_msgpack_writer writer
;
42 void capture_enum(struct lttng_msgpack_writer
*writer
,
43 struct lttng_interpreter_output
*output
)
45 lttng_msgpack_begin_map(writer
, 2);
46 lttng_msgpack_write_str(writer
, "type");
47 lttng_msgpack_write_str(writer
, "enum");
49 lttng_msgpack_write_str(writer
, "value");
51 switch (output
->type
) {
52 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
53 lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
55 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
56 lttng_msgpack_write_signed_integer(writer
, output
->u
.u
);
62 lttng_msgpack_end_map(writer
);
66 int64_t capture_sequence_element_signed(uint8_t *ptr
,
67 const struct lttng_ust_type_integer
*integer_type
)
70 unsigned int size
= integer_type
->size
;
71 bool byte_order_reversed
= integer_type
->reverse_byte_order
;
80 tmp
= *(int16_t *) ptr
;
81 if (byte_order_reversed
)
90 tmp
= *(int32_t *) ptr
;
91 if (byte_order_reversed
)
100 tmp
= *(int64_t *) ptr
;
101 if (byte_order_reversed
)
115 uint64_t capture_sequence_element_unsigned(uint8_t *ptr
,
116 const struct lttng_ust_type_integer
*integer_type
)
119 unsigned int size
= integer_type
->size
;
120 bool byte_order_reversed
= integer_type
->reverse_byte_order
;
129 tmp
= *(uint16_t *) ptr
;
130 if (byte_order_reversed
)
139 tmp
= *(uint32_t *) ptr
;
140 if (byte_order_reversed
)
149 tmp
= *(uint64_t *) ptr
;
150 if (byte_order_reversed
)
164 void capture_sequence(struct lttng_msgpack_writer
*writer
,
165 struct lttng_interpreter_output
*output
)
167 const struct lttng_ust_type_integer
*integer_type
;
168 const struct lttng_ust_type_common
*nested_type
;
173 lttng_msgpack_begin_array(writer
, output
->u
.sequence
.nr_elem
);
175 ptr
= (uint8_t *) output
->u
.sequence
.ptr
;
176 nested_type
= output
->u
.sequence
.nested_type
;
177 switch (nested_type
->type
) {
178 case lttng_ust_type_integer
:
179 integer_type
= lttng_ust_get_type_integer(nested_type
);
181 case lttng_ust_type_enum
:
182 /* Treat enumeration as an integer. */
183 integer_type
= lttng_ust_get_type_integer(lttng_ust_get_type_enum(nested_type
)->container_type
);
186 /* Capture of array of non-integer are not supported. */
189 signedness
= integer_type
->signedness
;
190 for (i
= 0; i
< output
->u
.sequence
.nr_elem
; i
++) {
192 lttng_msgpack_write_signed_integer(writer
,
193 capture_sequence_element_signed(ptr
, integer_type
));
195 lttng_msgpack_write_unsigned_integer(writer
,
196 capture_sequence_element_unsigned(ptr
, integer_type
));
200 * We assume that alignment is smaller or equal to the size.
201 * This currently holds true but if it changes in the future,
202 * we will want to change the pointer arithmetics below to
203 * take into account that the next element might be further
206 assert(integer_type
->alignment
<= integer_type
->size
);
208 /* Size is in number of bits. */
209 ptr
+= (integer_type
->size
/ CHAR_BIT
) ;
212 lttng_msgpack_end_array(writer
);
216 void notification_init(struct lttng_event_notifier_notification
*notif
,
217 struct lttng_ust_event_notifier
*event_notifier
)
219 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
221 notif
->event_notifier_token
= event_notifier
->priv
->parent
.user_token
;
222 notif
->notification_fd
= event_notifier
->priv
->group
->notification_fd
;
223 notif
->has_captures
= false;
225 if (event_notifier
->priv
->num_captures
> 0) {
226 lttng_msgpack_writer_init(writer
, notif
->capture_buf
,
227 CAPTURE_BUFFER_SIZE
);
229 lttng_msgpack_begin_array(writer
, event_notifier
->priv
->num_captures
);
230 notif
->has_captures
= true;
235 void notification_append_capture(
236 struct lttng_event_notifier_notification
*notif
,
237 struct lttng_interpreter_output
*output
)
239 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
241 switch (output
->type
) {
242 case LTTNG_INTERPRETER_TYPE_S64
:
243 lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
245 case LTTNG_INTERPRETER_TYPE_U64
:
246 lttng_msgpack_write_unsigned_integer(writer
, output
->u
.u
);
248 case LTTNG_INTERPRETER_TYPE_DOUBLE
:
249 lttng_msgpack_write_double(writer
, output
->u
.d
);
251 case LTTNG_INTERPRETER_TYPE_STRING
:
252 lttng_msgpack_write_str(writer
, output
->u
.str
.str
);
254 case LTTNG_INTERPRETER_TYPE_SEQUENCE
:
255 capture_sequence(writer
, output
);
257 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
258 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
259 capture_enum(writer
, output
);
267 void notification_append_empty_capture(
268 struct lttng_event_notifier_notification
*notif
)
270 lttng_msgpack_write_nil(¬if
->writer
);
273 static void record_error(struct lttng_ust_event_notifier
*event_notifier
)
275 struct lttng_event_notifier_group
*event_notifier_group
=
276 event_notifier
->priv
->group
;
277 struct lttng_counter
*error_counter
;
278 size_t dimension_index
[1];
281 error_counter
= CMM_LOAD_SHARED(event_notifier_group
->error_counter
);
283 * load-acquire paired with store-release orders creation of the
284 * error counter and setting error_counter_len before the
285 * error_counter is used.
286 * Currently a full memory barrier is used, which could be
287 * turned into acquire-release barriers.
290 /* This group may not have an error counter attached to it. */
294 dimension_index
[0] = event_notifier
->priv
->error_counter_index
;
295 ret
= event_notifier_group
->error_counter
->ops
->counter_add(
296 error_counter
->counter
, dimension_index
, 1);
302 void notification_send(struct lttng_event_notifier_notification
*notif
,
303 struct lttng_ust_event_notifier
*event_notifier
)
308 struct lttng_ust_abi_event_notifier_notification ust_notif
= {0};
313 ust_notif
.token
= event_notifier
->priv
->parent
.user_token
;
316 * Prepare sending the notification from multiple buffers using an
317 * array of `struct iovec`. The first buffer of the vector is
318 * notification structure itself and is always present.
320 iov
[0].iov_base
= &ust_notif
;
321 iov
[0].iov_len
= sizeof(ust_notif
);
323 if (notif
->has_captures
) {
325 * If captures were requested, the second buffer of the array
326 * is the capture buffer.
328 assert(notif
->writer
.buffer
);
329 content_len
= notif
->writer
.write_pos
- notif
->writer
.buffer
;
331 assert(content_len
> 0 && content_len
<= CAPTURE_BUFFER_SIZE
);
333 iov
[1].iov_base
= notif
->capture_buf
;
334 iov
[1].iov_len
= content_len
;
342 * Update the capture buffer size so that receiver of the buffer will
343 * know how much to expect.
345 ust_notif
.capture_buf_size
= content_len
;
347 /* Send all the buffers. */
348 ret
= ust_patient_writev(notif
->notification_fd
, iov
, iovec_count
);
350 if (errno
== EAGAIN
) {
351 record_error(event_notifier
);
352 DBG("Cannot send event_notifier notification without blocking: %s",
355 DBG("Error to sending event notifier notification: %s",
362 void lttng_event_notifier_notification_send(
363 struct lttng_ust_event_notifier
*event_notifier
,
364 const char *stack_data
,
365 struct lttng_ust_notification_ctx
*notif_ctx
)
368 * This function is called from the probe, we must do dynamic
369 * allocation in this context.
371 struct lttng_event_notifier_notification notif
= {0};
373 notification_init(¬if
, event_notifier
);
375 if (caa_unlikely(notif_ctx
->eval_capture
)) {
376 struct lttng_ust_bytecode_runtime
*capture_bc_runtime
;
379 * Iterate over all the capture bytecodes. If the interpreter
380 * functions returns successfully, append the value of the
381 * `output` parameter to the capture buffer. If the interpreter
382 * fails, append an empty capture to the buffer.
384 cds_list_for_each_entry_rcu(capture_bc_runtime
,
385 &event_notifier
->priv
->capture_bytecode_runtime_head
, node
) {
386 struct lttng_interpreter_output output
;
388 if (capture_bc_runtime
->interpreter_func(capture_bc_runtime
,
389 stack_data
, &output
) == LTTNG_UST_BYTECODE_INTERPRETER_OK
)
390 notification_append_capture(¬if
, &output
);
392 notification_append_empty_capture(¬if
);
397 * Send the notification (including the capture buffer) to the
400 notification_send(¬if
, event_notifier
);