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 struct lttng_event_notifier_notification
{
30 uint64_t event_notifier_token
;
31 uint8_t capture_buf
[CAPTURE_BUFFER_SIZE
];
32 struct lttng_msgpack_writer writer
;
37 int capture_enum(struct lttng_msgpack_writer
*writer
,
38 struct lttng_interpreter_output
*output
)
43 * Enums are captured as a map containing 2 key-value pairs. Such as:
47 ret
= lttng_msgpack_begin_map(writer
, 2);
52 ret
= lttng_msgpack_write_str(writer
, "type");
57 ret
= lttng_msgpack_write_str(writer
, "enum");
62 ret
= lttng_msgpack_write_str(writer
, "value");
67 switch (output
->type
) {
68 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
69 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
74 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
75 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.u
);
84 ret
= lttng_msgpack_end_map(writer
);
90 int64_t capture_sequence_element_signed(uint8_t *ptr
,
91 const struct lttng_kernel_type_integer
*type
)
94 unsigned int size
= type
->size
;
95 bool user
= type
->user
;
96 bool byte_order_reversed
= type
->reverse_byte_order
;
104 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int8_t)))
117 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int16_t)))
120 tmp
= *(int16_t *) ptr
;
122 if (byte_order_reversed
)
132 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int32_t)))
135 tmp
= *(int32_t *) ptr
;
137 if (byte_order_reversed
)
147 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(int64_t)))
150 tmp
= *(int64_t *) ptr
;
152 if (byte_order_reversed
)
165 uint64_t capture_sequence_element_unsigned(uint8_t *ptr
,
166 const struct lttng_kernel_type_integer
*type
)
169 unsigned int size
= type
->size
;
170 bool user
= type
->user
;
171 bool byte_order_reversed
= type
->reverse_byte_order
;
179 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint8_t)))
192 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint16_t)))
195 tmp
= *(uint16_t *) ptr
;
197 if (byte_order_reversed
)
207 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint32_t)))
210 tmp
= *(uint32_t *) ptr
;
212 if (byte_order_reversed
)
222 if (lttng_copy_from_user_check_nofault(&tmp
, ptr
, sizeof(uint64_t)))
225 tmp
= *(uint64_t *) ptr
;
227 if (byte_order_reversed
)
239 int capture_sequence(struct lttng_msgpack_writer
*writer
,
240 struct lttng_interpreter_output
*output
)
242 const struct lttng_kernel_type_integer
*integer_type
= NULL
;
243 const struct lttng_kernel_type_common
*nested_type
;
248 ret
= lttng_msgpack_begin_array(writer
, output
->u
.sequence
.nr_elem
);
253 ptr
= (uint8_t *) output
->u
.sequence
.ptr
;
254 nested_type
= output
->u
.sequence
.nested_type
;
255 switch (nested_type
->type
) {
256 case lttng_kernel_type_integer
:
257 integer_type
= lttng_kernel_get_type_integer(nested_type
);
259 case lttng_kernel_type_enum
:
260 /* Treat enumeration as an integer. */
261 integer_type
= lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type
)->container_type
);
264 /* Capture of array of non-integer are not supported. */
269 signedness
= integer_type
->signedness
;
270 for (i
= 0; i
< output
->u
.sequence
.nr_elem
; i
++) {
272 ret
= lttng_msgpack_write_signed_integer(writer
,
273 capture_sequence_element_signed(ptr
, integer_type
));
278 ret
= lttng_msgpack_write_unsigned_integer(writer
,
279 capture_sequence_element_unsigned(ptr
, integer_type
));
286 * We assume that alignment is smaller or equal to the size.
287 * This currently holds true but if it changes in the future,
288 * we will want to change the pointer arithmetics below to
289 * take into account that the next element might be further
292 WARN_ON_ONCE(integer_type
->alignment
> integer_type
->size
);
294 /* Size is in number of bits. */
295 ptr
+= (integer_type
->size
/ CHAR_BIT
) ;
298 ret
= lttng_msgpack_end_array(writer
);
304 int notification_append_capture(
305 struct lttng_event_notifier_notification
*notif
,
306 struct lttng_interpreter_output
*output
)
308 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
311 switch (output
->type
) {
312 case LTTNG_INTERPRETER_TYPE_S64
:
313 ret
= lttng_msgpack_write_signed_integer(writer
, output
->u
.s
);
315 case LTTNG_INTERPRETER_TYPE_U64
:
316 ret
= lttng_msgpack_write_unsigned_integer(writer
, output
->u
.u
);
318 case LTTNG_INTERPRETER_TYPE_STRING
:
319 if (output
->u
.str
.user
) {
320 ret
= lttng_msgpack_write_user_str(writer
, output
->u
.str
.user_str
);
322 ret
= lttng_msgpack_write_str(writer
, output
->u
.str
.str
);
325 case LTTNG_INTERPRETER_TYPE_SEQUENCE
:
326 ret
= capture_sequence(writer
, output
);
328 case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM
:
329 case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM
:
330 ret
= capture_enum(writer
, output
);
340 int notification_append_empty_capture(
341 struct lttng_event_notifier_notification
*notif
)
343 return lttng_msgpack_write_nil(¬if
->writer
);
347 int notification_init(struct lttng_event_notifier_notification
*notif
,
348 struct lttng_kernel_event_notifier
*event_notifier
)
350 struct lttng_msgpack_writer
*writer
= ¬if
->writer
;
353 notif
->has_captures
= false;
355 if (event_notifier
->priv
->num_captures
> 0) {
356 lttng_msgpack_writer_init(writer
, notif
->capture_buf
,
357 CAPTURE_BUFFER_SIZE
);
359 ret
= lttng_msgpack_begin_array(writer
, event_notifier
->priv
->num_captures
);
364 notif
->has_captures
= true;
372 void record_error(struct lttng_kernel_event_notifier
*event_notifier
)
375 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
376 struct lttng_counter
*error_counter
;
377 size_t dimension_index
[1];
381 * lttng_smp_load_acquire paired with lttng_smp_store_release orders
382 * creation of the error counter and setting error_counter_len
383 * before the error_counter is used.
385 error_counter
= lttng_smp_load_acquire(&event_notifier_group
->error_counter
);
386 /* This group may not have an error counter attached to it. */
390 dimension_index
[0] = event_notifier
->priv
->error_counter_index
;
392 ret
= error_counter
->ops
->counter_add(error_counter
->counter
,
399 void notification_send(struct lttng_event_notifier_notification
*notif
,
400 struct lttng_kernel_event_notifier
*event_notifier
)
402 struct lttng_event_notifier_group
*event_notifier_group
= event_notifier
->priv
->group
;
403 struct lttng_kernel_ring_buffer_ctx ctx
;
404 struct lttng_kernel_abi_event_notifier_notification kernel_notif
;
405 size_t capture_buffer_content_len
, reserve_size
;
408 reserve_size
= sizeof(kernel_notif
);
409 kernel_notif
.token
= event_notifier
->priv
->parent
.user_token
;
411 if (notif
->has_captures
) {
412 capture_buffer_content_len
= notif
->writer
.write_pos
- notif
->writer
.buffer
;
414 capture_buffer_content_len
= 0;
417 WARN_ON_ONCE(capture_buffer_content_len
> CAPTURE_BUFFER_SIZE
);
419 reserve_size
+= capture_buffer_content_len
;
420 kernel_notif
.capture_buf_size
= capture_buffer_content_len
;
422 lib_ring_buffer_ctx_init(&ctx
, event_notifier_group
->chan
, reserve_size
,
423 lttng_alignof(kernel_notif
), NULL
);
424 ret
= event_notifier_group
->ops
->event_reserve(&ctx
);
426 record_error(event_notifier
);
430 /* Write the notif structure. */
431 event_notifier_group
->ops
->event_write(&ctx
, &kernel_notif
,
432 sizeof(kernel_notif
), lttng_alignof(kernel_notif
));
435 * Write the capture buffer. No need to realigned as the below is a raw
438 event_notifier_group
->ops
->event_write(&ctx
, ¬if
->capture_buf
,
439 capture_buffer_content_len
, 1);
441 event_notifier_group
->ops
->event_commit(&ctx
);
442 irq_work_queue(&event_notifier_group
->wakeup_pending
);
445 void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier
*event_notifier
,
446 const char *stack_data
,
447 struct lttng_kernel_probe_ctx
*probe_ctx
,
448 struct lttng_kernel_notification_ctx
*notif_ctx
)
450 struct lttng_event_notifier_notification notif
= { 0 };
452 if (unlikely(!READ_ONCE(event_notifier
->parent
.enabled
)))
455 if (notification_init(¬if
, event_notifier
)) {
456 record_error(event_notifier
);
460 if (unlikely(notif_ctx
->eval_capture
)) {
461 struct lttng_kernel_bytecode_runtime
*capture_bc_runtime
;
464 * Iterate over all the capture bytecodes. If the interpreter
465 * functions returns successfully, append the value of the
466 * `output` parameter to the capture buffer. If the interpreter
467 * fails, append an empty capture to the buffer.
469 list_for_each_entry_rcu(capture_bc_runtime
,
470 &event_notifier
->priv
->capture_bytecode_runtime_head
, node
) {
471 struct lttng_interpreter_output output
;
475 lttng_msgpack_save_writer_pos(¬if
.writer
, &save_pos
);
476 if (capture_bc_runtime
->interpreter_func(capture_bc_runtime
,
477 stack_data
, probe_ctx
, &output
) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK
)
478 ret
= notification_append_capture(¬if
, &output
);
480 ret
= notification_append_empty_capture(¬if
);
483 * On append capture error, skip the field
484 * capture by restoring the msgpack writer
487 lttng_msgpack_restore_writer_pos(¬if
.writer
, save_pos
);
493 * Send the notification (including the capture buffer) to the
496 notification_send(¬if
, event_notifier
);