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 <lttng/probe-user.h>
16 #include <wrapper/barrier.h>
19 * The capture buffer size needs to be below 1024 bytes to avoid the
20 * frame to be larger than the 1024 limit enforced by the kernel. If we
21 * ever need to increase it, we will need to use a memory allocation
22 * scheme which allows allocating temporary memory chunks from the
23 * instrumentation sites. This could be done by adapting lttng
24 * tp-mempool to become nmi-safe and lock-free.
26 #define CAPTURE_BUFFER_SIZE 512
28 #define MSG_WRITE_NIL_LEN 1
30 struct lttng_event_notifier_notification
{
32 uint64_t event_notifier_token
;
33 uint8_t capture_buf
[CAPTURE_BUFFER_SIZE
];
34 struct lttng_msgpack_writer writer
;
39 int capture_enum(struct lttng_msgpack_writer
*writer
,
40 struct lttng_interpreter_output
*output
)
45 * Enums are captured as a map containing 2 key-value pairs. Such as:
49 ret
= lttng_msgpack_begin_map(writer
, 2);
54 ret
= lttng_msgpack_write_str(writer
, "type");
59 ret
= lttng_msgpack_write_str(writer
, "enum");
64 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
);
76 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
77 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.u
);
88 ret
= lttng_msgpack_end_map(writer
);
94 int capture_sequence_element_signed(uint8_t *ptr
,
95 const struct lttng_kernel_type_integer
*type
,
99 unsigned int size
= type
->size
;
100 bool user
= type
->user
;
101 bool byte_order_reversed
= type
->reverse_byte_order
;
109 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int8_t)))
122 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int16_t)))
125 tmp
= *(int16_t *) ptr
;
127 if (byte_order_reversed
)
137 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int32_t)))
140 tmp
= *(int32_t *) ptr
;
142 if (byte_order_reversed
)
152 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int64_t)))
155 tmp
= *(int64_t *) ptr
;
157 if (byte_order_reversed
)
172 int capture_sequence_element_unsigned(uint8_t *ptr
,
173 const struct lttng_kernel_type_integer
*type
,
177 unsigned int size
= type
->size
;
178 bool user
= type
->user
;
179 bool byte_order_reversed
= type
->reverse_byte_order
;
187 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint8_t)))
200 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint16_t)))
203 tmp
= *(uint16_t *) ptr
;
205 if (byte_order_reversed
)
215 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint32_t)))
218 tmp
= *(uint32_t *) ptr
;
220 if (byte_order_reversed
)
230 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint64_t)))
233 tmp
= *(uint64_t *) ptr
;
235 if (byte_order_reversed
)
249 int capture_sequence(struct lttng_msgpack_writer
*writer
,
250 struct lttng_interpreter_output
*output
)
252 const struct lttng_kernel_type_integer
*integer_type
= NULL
;
253 const struct lttng_kernel_type_common
*nested_type
;
258 ret
= lttng_msgpack_begin_array(writer
, output
->u
.sequence
.nr_elem
);
263 ptr
= (uint8_t *) output
->u
.sequence
.ptr
;
264 nested_type
= output
->u
.sequence
.nested_type
;
265 switch (nested_type
->type
) {
266 case lttng_kernel_type_integer
:
267 integer_type
= lttng_kernel_get_type_integer(nested_type
);
269 case lttng_kernel_type_enum
:
270 /* Treat enumeration as an integer. */
271 integer_type
= lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type
)->container_type
);
274 /* Capture of array of non-integer are not supported. */
279 signedness
= integer_type
->signedness
;
280 for (i
= 0; i
< output
->u
.sequence
.nr_elem
; i
++) {
284 ret
= capture_sequence_element_signed(ptr
, integer_type
, &v
);
288 ret
= lttng_msgpack_write_signed_integer(writer
, v
);
295 ret
= capture_sequence_element_unsigned(ptr
, integer_type
, &v
);
299 ret
= lttng_msgpack_write_unsigned_integer(writer
, v
);
306 * We assume that alignment is smaller or equal to the size.
307 * This currently holds true but if it changes in the future,
308 * we will want to change the pointer arithmetics below to
309 * take into account that the next element might be further
312 WARN_ON_ONCE(integer_type
->alignment
> integer_type
->size
);
314 /* Size is in number of bits. */
315 ptr
+= (integer_type
->size
/ CHAR_BIT
) ;
318 ret
= lttng_msgpack_end_array(writer
);
324 int notification_append_capture(
325 struct lttng_event_notifier_notification
*notif
,
326 struct lttng_interpreter_output
*output
)
328 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
331 switch (output
->type
) {
332 case LTTNG_INTERPRETER_TYPE_S64
:
333 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
335 case LTTNG_INTERPRETER_TYPE_U64
:
336 ret
= lttng_msgpack_write_unsigned_integer(writer
, output
->u
.u
);
338 case LTTNG_INTERPRETER_TYPE_STRING
:
339 if (output
->u
.str
.user
) {
340 ret
= lttng_msgpack_write_user_str(writer
, output
->u
.str
.user_str
);
342 ret
= lttng_msgpack_write_str(writer
, output
->u
.str
.str
);
345 case LTTNG_INTERPRETER_TYPE_SEQUENCE
:
346 ret
= capture_sequence(writer
, output
);
348 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
349 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
350 ret
= capture_enum(writer
, output
);
360 int notification_append_empty_capture(
361 struct lttng_event_notifier_notification
*notif
)
363 return lttng_msgpack_write_nil(¬if
->writer
);
367 int notification_init(struct lttng_event_notifier_notification
*notif
,
368 struct lttng_kernel_event_notifier
*event_notifier
)
370 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
373 notif
->has_captures
= false;
375 if (event_notifier
->priv
->num_captures
> 0) {
376 lttng_msgpack_writer_init(writer
, notif
->capture_buf
,
377 CAPTURE_BUFFER_SIZE
);
379 ret
= lttng_msgpack_begin_array(writer
, event_notifier
->priv
->num_captures
);
384 notif
->has_captures
= true;
392 void record_error(struct lttng_kernel_event_notifier
*event_notifier
)
395 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
396 struct lttng_counter
*error_counter
;
397 size_t dimension_index
[1];
401 * lttng_smp_load_acquire paired with lttng_smp_store_release orders
402 * creation of the error counter and setting error_counter_len
403 * before the error_counter is used.
405 error_counter
= lttng_smp_load_acquire(&event_notifier_group
->error_counter
);
406 /* This group may not have an error counter attached to it. */
410 dimension_index
[0] = event_notifier
->priv
->error_counter_index
;
412 ret
= error_counter
->ops
->counter_add(error_counter
->counter
,
419 void notification_send(struct lttng_event_notifier_notification
*notif
,
420 struct lttng_kernel_event_notifier
*event_notifier
)
422 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
423 struct lttng_kernel_ring_buffer_ctx ctx
;
424 struct lttng_kernel_abi_event_notifier_notification kernel_notif
;
425 size_t capture_buffer_content_len
, reserve_size
;
428 reserve_size
= sizeof(kernel_notif
);
429 kernel_notif
.token
= event_notifier
->priv
->parent
.user_token
;
431 if (notif
->has_captures
) {
432 capture_buffer_content_len
= notif
->writer
.write_pos
- notif
->writer
.buffer
;
434 capture_buffer_content_len
= 0;
437 WARN_ON_ONCE(capture_buffer_content_len
> CAPTURE_BUFFER_SIZE
);
439 reserve_size
+= capture_buffer_content_len
;
440 kernel_notif
.capture_buf_size
= capture_buffer_content_len
;
442 lib_ring_buffer_ctx_init(&ctx
, event_notifier_group
->chan
, reserve_size
,
443 lttng_alignof(kernel_notif
), NULL
);
444 ret
= event_notifier_group
->ops
->event_reserve(&ctx
);
446 record_error(event_notifier
);
450 /* Write the notif structure. */
451 event_notifier_group
->ops
->event_write(&ctx
, &kernel_notif
,
452 sizeof(kernel_notif
), lttng_alignof(kernel_notif
));
455 * Write the capture buffer. No need to realigned as the below is a raw
458 event_notifier_group
->ops
->event_write(&ctx
, ¬if
->capture_buf
,
459 capture_buffer_content_len
, 1);
461 event_notifier_group
->ops
->event_commit(&ctx
);
462 irq_work_queue(&event_notifier_group
->wakeup_pending
);
466 * Validate that the buffer has enough room to hold empty capture fields.
469 bool validate_buffer_len(struct lttng_event_notifier_notification
*notif
, size_t captures_left
)
471 if (notif
->writer
.end_write_pos
- notif
->writer
.write_pos
< MSG_WRITE_NIL_LEN
* captures_left
)
476 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier
*event_notifier
,
477 const char *stack_data
,
478 struct lttng_kernel_probe_ctx
*probe_ctx
,
479 struct lttng_kernel_notification_ctx
*notif_ctx
)
481 struct lttng_event_notifier_notification notif
= { 0 };
482 size_t captures_left
;
484 if (notification_init(¬if
, event_notifier
))
487 captures_left
= event_notifier
->priv
->num_captures
;
488 if (!validate_buffer_len(¬if
, captures_left
))
491 if (unlikely(notif_ctx
->eval_capture
)) {
492 struct lttng_kernel_bytecode_runtime
*capture_bc_runtime
;
495 * Iterate over all the capture bytecodes. If the interpreter
496 * functions returns successfully, append the value of the
497 * `output` parameter to the capture buffer. If the interpreter
498 * fails, append an empty capture to the buffer.
500 list_for_each_entry_rcu(capture_bc_runtime
,
501 &event_notifier
->priv
->capture_bytecode_runtime_head
, node
) {
502 struct lttng_interpreter_output output
;
506 lttng_msgpack_save_writer_pos(¬if
.writer
, &save_pos
);
508 if (capture_bc_runtime
->interpreter_func(capture_bc_runtime
,
509 stack_data
, probe_ctx
, &output
) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK
)
510 ret
= notification_append_capture(¬if
, &output
);
511 if (ret
|| !validate_buffer_len(¬if
, captures_left
)) {
513 * On append capture error or if the generated
514 * buffer data would not leave enough room to
515 * write empty capture fields for the remaining
516 * fields, skip the field capture by restoring
517 * the msgpack writer position and writing an
518 * empty capture field.
520 lttng_msgpack_restore_writer_pos(¬if
.writer
, save_pos
);
521 ret
= notification_append_empty_capture(¬if
);
527 if (notif
.has_captures
&& lttng_msgpack_end_array(¬if
.writer
))
531 * Send the notification (including the capture buffer) to the
534 notification_send(¬if
, event_notifier
);
538 record_error(event_notifier
);