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 "ust-events-internal.h"
18 #include "../libmsgpack/msgpack.h"
19 #include "lttng-bytecode.h"
20 #include "ust-share.h"
23 * We want this write to be atomic AND non-blocking, meaning that we
24 * want to write either everything OR nothing.
25 * According to `pipe(7)`, writes that are less than `PIPE_BUF` bytes must be
26 * atomic, so we bound the capture buffer size to the `PIPE_BUF` minus the size
27 * of the notification struct we are sending alongside the capture buffer.
29 #define CAPTURE_BUFFER_SIZE \
30 (PIPE_BUF - sizeof(struct lttng_ust_abi_event_notifier_notification) - 1)
32 struct lttng_event_notifier_notification
{
34 uint64_t event_notifier_token
;
35 uint8_t capture_buf
[CAPTURE_BUFFER_SIZE
];
36 struct lttng_msgpack_writer writer
;
41 void capture_enum(struct lttng_msgpack_writer
*writer
,
42 struct lttng_interpreter_output
*output
)
44 lttng_msgpack_begin_map(writer
, 2);
45 lttng_msgpack_write_str(writer
, "type");
46 lttng_msgpack_write_str(writer
, "enum");
48 lttng_msgpack_write_str(writer
, "value");
50 switch (output
->type
) {
51 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
52 lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
54 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
55 lttng_msgpack_write_signed_integer(writer
, output
->u
.u
);
61 lttng_msgpack_end_map(writer
);
65 int64_t capture_sequence_element_signed(uint8_t *ptr
,
66 struct lttng_ust_type_integer
*integer_type
)
69 unsigned int size
= integer_type
->size
;
70 bool byte_order_reversed
= integer_type
->reverse_byte_order
;
79 tmp
= *(int16_t *) ptr
;
80 if (byte_order_reversed
)
89 tmp
= *(int32_t *) ptr
;
90 if (byte_order_reversed
)
99 tmp
= *(int64_t *) ptr
;
100 if (byte_order_reversed
)
114 uint64_t capture_sequence_element_unsigned(uint8_t *ptr
,
115 struct lttng_ust_type_integer
*integer_type
)
118 unsigned int size
= integer_type
->size
;
119 bool byte_order_reversed
= integer_type
->reverse_byte_order
;
128 tmp
= *(uint16_t *) ptr
;
129 if (byte_order_reversed
)
138 tmp
= *(uint32_t *) ptr
;
139 if (byte_order_reversed
)
148 tmp
= *(uint64_t *) ptr
;
149 if (byte_order_reversed
)
163 void capture_sequence(struct lttng_msgpack_writer
*writer
,
164 struct lttng_interpreter_output
*output
)
166 struct lttng_ust_type_integer
*integer_type
;
167 struct lttng_ust_type_common
*nested_type
;
172 lttng_msgpack_begin_array(writer
, output
->u
.sequence
.nr_elem
);
174 ptr
= (uint8_t *) output
->u
.sequence
.ptr
;
175 nested_type
= output
->u
.sequence
.nested_type
;
176 switch (nested_type
->type
) {
177 case lttng_ust_type_integer
:
178 integer_type
= lttng_ust_get_type_integer(nested_type
);
180 case lttng_ust_type_enum
:
181 /* Treat enumeration as an integer. */
182 integer_type
= lttng_ust_get_type_integer(lttng_ust_get_type_enum(nested_type
)->container_type
);
185 /* Capture of array of non-integer are not supported. */
188 signedness
= integer_type
->signedness
;
189 for (i
= 0; i
< output
->u
.sequence
.nr_elem
; i
++) {
191 lttng_msgpack_write_signed_integer(writer
,
192 capture_sequence_element_signed(ptr
, integer_type
));
194 lttng_msgpack_write_unsigned_integer(writer
,
195 capture_sequence_element_unsigned(ptr
, integer_type
));
199 * We assume that alignment is smaller or equal to the size.
200 * This currently holds true but if it changes in the future,
201 * we will want to change the pointer arithmetics below to
202 * take into account that the next element might be further
205 assert(integer_type
->alignment
<= integer_type
->size
);
207 /* Size is in number of bits. */
208 ptr
+= (integer_type
->size
/ CHAR_BIT
) ;
211 lttng_msgpack_end_array(writer
);
215 void notification_init(struct lttng_event_notifier_notification
*notif
,
216 struct lttng_ust_event_notifier
*event_notifier
)
218 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
220 notif
->event_notifier_token
= event_notifier
->priv
->parent
.user_token
;
221 notif
->notification_fd
= event_notifier
->priv
->group
->notification_fd
;
222 notif
->has_captures
= false;
224 if (event_notifier
->priv
->num_captures
> 0) {
225 lttng_msgpack_writer_init(writer
, notif
->capture_buf
,
226 CAPTURE_BUFFER_SIZE
);
228 lttng_msgpack_begin_array(writer
, event_notifier
->priv
->num_captures
);
229 notif
->has_captures
= true;
234 void notification_append_capture(
235 struct lttng_event_notifier_notification
*notif
,
236 struct lttng_interpreter_output
*output
)
238 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
240 switch (output
->type
) {
241 case LTTNG_INTERPRETER_TYPE_S64
:
242 lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
244 case LTTNG_INTERPRETER_TYPE_U64
:
245 lttng_msgpack_write_unsigned_integer(writer
, output
->u
.u
);
247 case LTTNG_INTERPRETER_TYPE_DOUBLE
:
248 lttng_msgpack_write_double(writer
, output
->u
.d
);
250 case LTTNG_INTERPRETER_TYPE_STRING
:
251 lttng_msgpack_write_str(writer
, output
->u
.str
.str
);
253 case LTTNG_INTERPRETER_TYPE_SEQUENCE
:
254 capture_sequence(writer
, output
);
256 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
257 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
258 capture_enum(writer
, output
);
266 void notification_append_empty_capture(
267 struct lttng_event_notifier_notification
*notif
)
269 lttng_msgpack_write_nil(¬if
->writer
);
272 static void record_error(struct lttng_ust_event_notifier
*event_notifier
)
274 struct lttng_event_notifier_group
*event_notifier_group
=
275 event_notifier
->priv
->group
;
276 struct lttng_counter
*error_counter
;
277 size_t dimension_index
[1];
280 error_counter
= CMM_LOAD_SHARED(event_notifier_group
->error_counter
);
282 * load-acquire paired with store-release orders creation of the
283 * error counter and setting error_counter_len before the
284 * error_counter is used.
285 * Currently a full memory barrier is used, which could be
286 * turned into acquire-release barriers.
289 /* This group may not have an error counter attached to it. */
293 dimension_index
[0] = event_notifier
->priv
->error_counter_index
;
294 ret
= event_notifier_group
->error_counter
->ops
->counter_add(
295 error_counter
->counter
, dimension_index
, 1);
301 void notification_send(struct lttng_event_notifier_notification
*notif
,
302 struct lttng_ust_event_notifier
*event_notifier
)
307 struct lttng_ust_abi_event_notifier_notification ust_notif
= {0};
312 ust_notif
.token
= event_notifier
->priv
->parent
.user_token
;
315 * Prepare sending the notification from multiple buffers using an
316 * array of `struct iovec`. The first buffer of the vector is
317 * notification structure itself and is always present.
319 iov
[0].iov_base
= &ust_notif
;
320 iov
[0].iov_len
= sizeof(ust_notif
);
322 if (notif
->has_captures
) {
324 * If captures were requested, the second buffer of the array
325 * is the capture buffer.
327 assert(notif
->writer
.buffer
);
328 content_len
= notif
->writer
.write_pos
- notif
->writer
.buffer
;
330 assert(content_len
> 0 && content_len
<= CAPTURE_BUFFER_SIZE
);
332 iov
[1].iov_base
= notif
->capture_buf
;
333 iov
[1].iov_len
= content_len
;
341 * Update the capture buffer size so that receiver of the buffer will
342 * know how much to expect.
344 ust_notif
.capture_buf_size
= content_len
;
346 /* Send all the buffers. */
347 ret
= ust_patient_writev(notif
->notification_fd
, iov
, iovec_count
);
349 if (errno
== EAGAIN
) {
350 record_error(event_notifier
);
351 DBG("Cannot send event_notifier notification without blocking: %s",
354 DBG("Error to sending event notifier notification: %s",
361 void lttng_event_notifier_notification_send(
362 struct lttng_ust_event_notifier
*event_notifier
,
363 const char *stack_data
,
364 struct lttng_ust_notification_ctx
*notif_ctx
)
367 * This function is called from the probe, we must do dynamic
368 * allocation in this context.
370 struct lttng_event_notifier_notification notif
= {0};
372 notification_init(¬if
, event_notifier
);
374 if (caa_unlikely(notif_ctx
->eval_capture
)) {
375 struct lttng_ust_bytecode_runtime
*capture_bc_runtime
;
378 * Iterate over all the capture bytecodes. If the interpreter
379 * functions returns successfully, append the value of the
380 * `output` parameter to the capture buffer. If the interpreter
381 * fails, append an empty capture to the buffer.
383 cds_list_for_each_entry_rcu(capture_bc_runtime
,
384 &event_notifier
->priv
->capture_bytecode_runtime_head
, node
) {
385 struct lttng_interpreter_output output
;
387 if (capture_bc_runtime
->interpreter_func(capture_bc_runtime
,
388 stack_data
, &output
) == LTTNG_UST_BYTECODE_INTERPRETER_OK
)
389 notification_append_capture(¬if
, &output
);
391 notification_append_empty_capture(¬if
);
396 * Send the notification (including the capture buffer) to the
399 notification_send(¬if
, event_notifier
);