1 /* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
3 * lttng-event-notifier-notification.c
5 * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
10 #include <lttng/lttng-bytecode.h>
11 #include <lttng/events.h>
12 #include <lttng/msgpack.h>
13 #include <lttng/event-notifier-notification.h>
14 #include <wrapper/barrier.h>
17 * The capture buffer size needs to be below 1024 bytes to avoid the
18 * frame to be larger than the 1024 limit enforced by the kernel. If we
19 * ever need to increase it, we will need to use a memory allocation
20 * scheme which allows allocating temporary memory chunks from the
21 * instrumentation sites. This could be done by adapting lttng
22 * tp-mempool to become nmi-safe and lock-free.
24 #define CAPTURE_BUFFER_SIZE 512
26 struct lttng_event_notifier_notification
{
28 uint64_t event_notifier_token
;
29 uint8_t capture_buf
[CAPTURE_BUFFER_SIZE
];
30 struct lttng_msgpack_writer writer
;
35 int capture_enum(struct lttng_msgpack_writer
*writer
,
36 struct lttng_interpreter_output
*output
)
41 * Enums are captured as a map containing 2 key-value pairs. Such as:
45 ret
= lttng_msgpack_begin_map(writer
, 2);
51 ret
= lttng_msgpack_write_str(writer
, "type");
57 ret
= lttng_msgpack_write_str(writer
, "enum");
63 ret
= lttng_msgpack_write_str(writer
, "value");
69 switch (output
->type
) {
70 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
71 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
77 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
78 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.u
);
88 ret
= lttng_msgpack_end_map(writer
);
97 int64_t capture_sequence_element_signed(uint8_t *ptr
,
98 const struct lttng_integer_type
*type
)
101 unsigned int size
= type
->size
;
102 bool byte_order_reversed
= type
->reverse_byte_order
;
111 tmp
= *(int16_t *) ptr
;
112 if (byte_order_reversed
)
121 tmp
= *(int32_t *) ptr
;
122 if (byte_order_reversed
)
131 tmp
= *(int64_t *) ptr
;
132 if (byte_order_reversed
)
146 uint64_t capture_sequence_element_unsigned(uint8_t *ptr
,
147 const struct lttng_integer_type
*type
)
150 unsigned int size
= type
->size
;
151 bool byte_order_reversed
= type
->reverse_byte_order
;
160 tmp
= *(uint16_t *) ptr
;
161 if (byte_order_reversed
)
170 tmp
= *(uint32_t *) ptr
;
171 if (byte_order_reversed
)
180 tmp
= *(uint64_t *) ptr
;
181 if (byte_order_reversed
)
194 int capture_sequence(struct lttng_msgpack_writer
*writer
,
195 struct lttng_interpreter_output
*output
)
197 const struct lttng_integer_type
*integer_type
= NULL
;
198 const struct lttng_type
*nested_type
;
203 ret
= lttng_msgpack_begin_array(writer
, output
->u
.sequence
.nr_elem
);
209 ptr
= (uint8_t *) output
->u
.sequence
.ptr
;
210 nested_type
= output
->u
.sequence
.nested_type
;
211 switch (nested_type
->atype
) {
213 integer_type
= &nested_type
->u
.integer
;
215 case atype_enum_nestable
:
216 /* Treat enumeration as an integer. */
217 integer_type
= &nested_type
->u
.enum_nestable
.container_type
->u
.integer
;
220 /* Capture of array of non-integer are not supported. */
223 signedness
= integer_type
->signedness
;
224 for (i
= 0; i
< output
->u
.sequence
.nr_elem
; i
++) {
226 ret
= lttng_msgpack_write_signed_integer(writer
,
227 capture_sequence_element_signed(ptr
, integer_type
));
233 ret
= lttng_msgpack_write_unsigned_integer(writer
,
234 capture_sequence_element_unsigned(ptr
, integer_type
));
242 * We assume that alignment is smaller or equal to the size.
243 * This currently holds true but if it changes in the future,
244 * we will want to change the pointer arithmetics below to
245 * take into account that the next element might be further
248 WARN_ON(integer_type
->alignment
> integer_type
->size
);
250 /* Size is in number of bits. */
251 ptr
+= (integer_type
->size
/ CHAR_BIT
) ;
254 ret
= lttng_msgpack_end_array(writer
);
262 int notification_append_capture(
263 struct lttng_event_notifier_notification
*notif
,
264 struct lttng_interpreter_output
*output
)
266 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
269 switch (output
->type
) {
270 case LTTNG_INTERPRETER_TYPE_S64
:
271 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
277 case LTTNG_INTERPRETER_TYPE_U64
:
278 ret
= lttng_msgpack_write_unsigned_integer(writer
, output
->u
.u
);
284 case LTTNG_INTERPRETER_TYPE_STRING
:
285 ret
= lttng_msgpack_write_str(writer
, output
->u
.str
.str
);
291 case LTTNG_INTERPRETER_TYPE_SEQUENCE
:
292 ret
= capture_sequence(writer
, output
);
298 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
299 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
300 ret
= capture_enum(writer
, output
);
315 int notification_append_empty_capture(
316 struct lttng_event_notifier_notification
*notif
)
318 int ret
= lttng_msgpack_write_nil(¬if
->writer
);
326 int notification_init(struct lttng_event_notifier_notification
*notif
,
327 struct lttng_event_notifier
*event_notifier
)
329 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
332 notif
->has_captures
= false;
334 if (event_notifier
->num_captures
> 0) {
335 lttng_msgpack_writer_init(writer
, notif
->capture_buf
,
336 CAPTURE_BUFFER_SIZE
);
338 ret
= lttng_msgpack_begin_array(writer
, event_notifier
->num_captures
);
344 notif
->has_captures
= true;
352 void record_error(struct lttng_event_notifier
*event_notifier
)
355 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->group
;
356 struct lttng_counter
*error_counter
;
357 size_t dimension_index
[1];
361 * lttng_smp_load_acquire paired with lttng_smp_store_release orders
362 * creation of the error counter and setting error_counter_len
363 * before the error_counter is used.
365 error_counter
= lttng_smp_load_acquire(&event_notifier_group
->error_counter
);
366 /* This group may not have an error counter attached to it. */
370 dimension_index
[0] = event_notifier
->error_counter_index
;
372 ret
= error_counter
->ops
->counter_add(error_counter
->counter
,
379 void notification_send(struct lttng_event_notifier_notification
*notif
,
380 struct lttng_event_notifier
*event_notifier
)
382 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->group
;
383 struct lib_ring_buffer_ctx ctx
;
384 struct lttng_kernel_event_notifier_notification kernel_notif
;
385 size_t capture_buffer_content_len
, reserve_size
;
388 reserve_size
= sizeof(kernel_notif
);
389 kernel_notif
.token
= event_notifier
->user_token
;
391 if (notif
->has_captures
) {
392 capture_buffer_content_len
= notif
->writer
.write_pos
- notif
->writer
.buffer
;
394 capture_buffer_content_len
= 0;
397 WARN_ON_ONCE(capture_buffer_content_len
> CAPTURE_BUFFER_SIZE
);
399 reserve_size
+= capture_buffer_content_len
;
400 kernel_notif
.capture_buf_size
= capture_buffer_content_len
;
402 lib_ring_buffer_ctx_init(&ctx
, event_notifier_group
->chan
, NULL
, reserve_size
,
403 lttng_alignof(kernel_notif
), -1);
404 ret
= event_notifier_group
->ops
->event_reserve(&ctx
, 0);
406 record_error(event_notifier
);
410 lib_ring_buffer_align_ctx(&ctx
, lttng_alignof(kernel_notif
));
412 /* Write the notif structure. */
413 event_notifier_group
->ops
->event_write(&ctx
, &kernel_notif
,
414 sizeof(kernel_notif
));
417 * Write the capture buffer. No need to realigned as the below is a raw
420 event_notifier_group
->ops
->event_write(&ctx
, ¬if
->capture_buf
,
421 capture_buffer_content_len
);
423 event_notifier_group
->ops
->event_commit(&ctx
);
424 irq_work_queue(&event_notifier_group
->wakeup_pending
);
427 void lttng_event_notifier_notification_send(struct lttng_event_notifier
*event_notifier
,
428 struct lttng_probe_ctx
*lttng_probe_ctx
,
429 const char *stack_data
)
431 struct lttng_event_notifier_notification notif
= { 0 };
434 if (unlikely(!READ_ONCE(event_notifier
->enabled
)))
437 ret
= notification_init(¬if
, event_notifier
);
443 if (unlikely(!list_empty(&event_notifier
->capture_bytecode_runtime_head
))) {
444 struct lttng_bytecode_runtime
*capture_bc_runtime
;
447 * Iterate over all the capture bytecodes. If the interpreter
448 * functions returns successfully, append the value of the
449 * `output` parameter to the capture buffer. If the interpreter
450 * fails, append an empty capture to the buffer.
452 list_for_each_entry(capture_bc_runtime
,
453 &event_notifier
->capture_bytecode_runtime_head
, node
) {
454 struct lttng_interpreter_output output
;
456 if (capture_bc_runtime
->interpreter_funcs
.capture(capture_bc_runtime
,
457 lttng_probe_ctx
, stack_data
, &output
) & LTTNG_INTERPRETER_RECORD_FLAG
)
458 ret
= notification_append_capture(¬if
, &output
);
460 ret
= notification_append_empty_capture(¬if
);
463 printk(KERN_WARNING
"Error appending capture to notification");
468 * Send the notification (including the capture buffer) to the
471 notification_send(¬if
, event_notifier
);