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 <lttng/events-internal.h>
15 #include <wrapper/barrier.h>
18 * The capture buffer size needs to be below 1024 bytes to avoid the
19 * frame to be larger than the 1024 limit enforced by the kernel. If we
20 * ever need to increase it, we will need to use a memory allocation
21 * scheme which allows allocating temporary memory chunks from the
22 * instrumentation sites. This could be done by adapting lttng
23 * tp-mempool to become nmi-safe and lock-free.
25 #define CAPTURE_BUFFER_SIZE 512
27 struct lttng_event_notifier_notification
{
29 uint64_t event_notifier_token
;
30 uint8_t capture_buf
[CAPTURE_BUFFER_SIZE
];
31 struct lttng_msgpack_writer writer
;
36 int capture_enum(struct lttng_msgpack_writer
*writer
,
37 struct lttng_interpreter_output
*output
)
42 * Enums are captured as a map containing 2 key-value pairs. Such as:
46 ret
= lttng_msgpack_begin_map(writer
, 2);
52 ret
= lttng_msgpack_write_str(writer
, "type");
58 ret
= lttng_msgpack_write_str(writer
, "enum");
64 ret
= lttng_msgpack_write_str(writer
, "value");
70 switch (output
->type
) {
71 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
72 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
78 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
79 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.u
);
89 ret
= lttng_msgpack_end_map(writer
);
98 int64_t capture_sequence_element_signed(uint8_t *ptr
,
99 const struct lttng_kernel_type_integer
*type
)
102 unsigned int size
= type
->size
;
103 bool byte_order_reversed
= type
->reverse_byte_order
;
112 tmp
= *(int16_t *) ptr
;
113 if (byte_order_reversed
)
122 tmp
= *(int32_t *) ptr
;
123 if (byte_order_reversed
)
132 tmp
= *(int64_t *) ptr
;
133 if (byte_order_reversed
)
147 uint64_t capture_sequence_element_unsigned(uint8_t *ptr
,
148 const struct lttng_kernel_type_integer
*type
)
151 unsigned int size
= type
->size
;
152 bool byte_order_reversed
= type
->reverse_byte_order
;
161 tmp
= *(uint16_t *) ptr
;
162 if (byte_order_reversed
)
171 tmp
= *(uint32_t *) ptr
;
172 if (byte_order_reversed
)
181 tmp
= *(uint64_t *) ptr
;
182 if (byte_order_reversed
)
195 int capture_sequence(struct lttng_msgpack_writer
*writer
,
196 struct lttng_interpreter_output
*output
)
198 const struct lttng_kernel_type_integer
*integer_type
= NULL
;
199 const struct lttng_kernel_type_common
*nested_type
;
204 ret
= lttng_msgpack_begin_array(writer
, output
->u
.sequence
.nr_elem
);
210 ptr
= (uint8_t *) output
->u
.sequence
.ptr
;
211 nested_type
= output
->u
.sequence
.nested_type
;
212 switch (nested_type
->type
) {
213 case lttng_kernel_type_integer
:
214 integer_type
= lttng_kernel_get_type_integer(nested_type
);
216 case lttng_kernel_type_enum
:
217 /* Treat enumeration as an integer. */
218 integer_type
= lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type
)->container_type
);
221 /* Capture of array of non-integer are not supported. */
224 signedness
= integer_type
->signedness
;
225 for (i
= 0; i
< output
->u
.sequence
.nr_elem
; i
++) {
227 ret
= lttng_msgpack_write_signed_integer(writer
,
228 capture_sequence_element_signed(ptr
, integer_type
));
234 ret
= lttng_msgpack_write_unsigned_integer(writer
,
235 capture_sequence_element_unsigned(ptr
, integer_type
));
243 * We assume that alignment is smaller or equal to the size.
244 * This currently holds true but if it changes in the future,
245 * we will want to change the pointer arithmetics below to
246 * take into account that the next element might be further
249 WARN_ON(integer_type
->alignment
> integer_type
->size
);
251 /* Size is in number of bits. */
252 ptr
+= (integer_type
->size
/ CHAR_BIT
) ;
255 ret
= lttng_msgpack_end_array(writer
);
263 int notification_append_capture(
264 struct lttng_event_notifier_notification
*notif
,
265 struct lttng_interpreter_output
*output
)
267 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
270 switch (output
->type
) {
271 case LTTNG_INTERPRETER_TYPE_S64
:
272 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
278 case LTTNG_INTERPRETER_TYPE_U64
:
279 ret
= lttng_msgpack_write_unsigned_integer(writer
, output
->u
.u
);
285 case LTTNG_INTERPRETER_TYPE_STRING
:
286 ret
= lttng_msgpack_write_str(writer
, output
->u
.str
.str
);
292 case LTTNG_INTERPRETER_TYPE_SEQUENCE
:
293 ret
= capture_sequence(writer
, output
);
299 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
300 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
301 ret
= capture_enum(writer
, output
);
316 int notification_append_empty_capture(
317 struct lttng_event_notifier_notification
*notif
)
319 int ret
= lttng_msgpack_write_nil(¬if
->writer
);
327 int notification_init(struct lttng_event_notifier_notification
*notif
,
328 struct lttng_kernel_event_notifier
*event_notifier
)
330 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
333 notif
->has_captures
= false;
335 if (event_notifier
->priv
->num_captures
> 0) {
336 lttng_msgpack_writer_init(writer
, notif
->capture_buf
,
337 CAPTURE_BUFFER_SIZE
);
339 ret
= lttng_msgpack_begin_array(writer
, event_notifier
->priv
->num_captures
);
345 notif
->has_captures
= true;
353 void record_error(struct lttng_kernel_event_notifier
*event_notifier
)
356 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
357 struct lttng_counter
*error_counter
;
358 size_t dimension_index
[1];
362 * lttng_smp_load_acquire paired with lttng_smp_store_release orders
363 * creation of the error counter and setting error_counter_len
364 * before the error_counter is used.
366 error_counter
= lttng_smp_load_acquire(&event_notifier_group
->error_counter
);
367 /* This group may not have an error counter attached to it. */
371 dimension_index
[0] = event_notifier
->priv
->error_counter_index
;
373 ret
= error_counter
->ops
->counter_add(error_counter
->counter
,
380 void notification_send(struct lttng_event_notifier_notification
*notif
,
381 struct lttng_kernel_event_notifier
*event_notifier
)
383 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
384 struct lttng_kernel_ring_buffer_ctx ctx
;
385 struct lttng_kernel_abi_event_notifier_notification kernel_notif
;
386 size_t capture_buffer_content_len
, reserve_size
;
389 reserve_size
= sizeof(kernel_notif
);
390 kernel_notif
.token
= event_notifier
->priv
->parent
.user_token
;
392 if (notif
->has_captures
) {
393 capture_buffer_content_len
= notif
->writer
.write_pos
- notif
->writer
.buffer
;
395 capture_buffer_content_len
= 0;
398 WARN_ON_ONCE(capture_buffer_content_len
> CAPTURE_BUFFER_SIZE
);
400 reserve_size
+= capture_buffer_content_len
;
401 kernel_notif
.capture_buf_size
= capture_buffer_content_len
;
403 lib_ring_buffer_ctx_init(&ctx
, event_notifier_group
->chan
, reserve_size
,
404 lttng_alignof(kernel_notif
), NULL
);
405 ret
= event_notifier_group
->ops
->event_reserve(&ctx
);
407 record_error(event_notifier
);
411 /* Write the notif structure. */
412 event_notifier_group
->ops
->event_write(&ctx
, &kernel_notif
,
413 sizeof(kernel_notif
), lttng_alignof(kernel_notif
));
416 * Write the capture buffer. No need to realigned as the below is a raw
419 event_notifier_group
->ops
->event_write(&ctx
, ¬if
->capture_buf
,
420 capture_buffer_content_len
, 1);
422 event_notifier_group
->ops
->event_commit(&ctx
);
423 irq_work_queue(&event_notifier_group
->wakeup_pending
);
426 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier
*event_notifier
,
427 const char *stack_data
,
428 struct lttng_kernel_probe_ctx
*probe_ctx
,
429 struct lttng_kernel_notification_ctx
*notif_ctx
)
431 struct lttng_event_notifier_notification notif
= { 0 };
434 if (unlikely(!READ_ONCE(event_notifier
->parent
.enabled
)))
437 ret
= notification_init(¬if
, event_notifier
);
443 if (unlikely(notif_ctx
->eval_capture
)) {
444 struct lttng_kernel_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_rcu(capture_bc_runtime
,
453 &event_notifier
->priv
->capture_bytecode_runtime_head
, node
) {
454 struct lttng_interpreter_output output
;
456 if (capture_bc_runtime
->interpreter_func(capture_bc_runtime
,
457 stack_data
, probe_ctx
, &output
) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK
)
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
);