[lttng-ust.git] / src / lib / lttng-ust / event-notifier-notification.c

/*
 * SPDX-License-Identifier: LGPL-2.1-only
 *
 * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
 */

#define _LGPL_SOURCE

#include <assert.h>
#include <errno.h>
#include <limits.h>

#include <lttng/ust-endian.h>
#include "common/logging.h"
#include <urcu/rculist.h>

#include "lttng-tracer-core.h"
#include "lib/lttng-ust/events.h"
#include "common/msgpack/msgpack.h"
#include "lttng-bytecode.h"
#include "common/patient.h"

/*
 * We want this write to be atomic AND non-blocking, meaning that we
 * want to write either everything OR nothing.
 * According to `pipe(7)`, writes that are less than `PIPE_BUF` bytes must be
 * atomic, so we bound the capture buffer size to the `PIPE_BUF` minus the size
 * of the notification struct we are sending alongside the capture buffer.
 */
#define CAPTURE_BUFFER_SIZE \
	(PIPE_BUF - sizeof(struct lttng_ust_abi_event_notifier_notification) - 1)

#define MSG_WRITE_NIL_LEN 1

struct lttng_event_notifier_notification {
	int notification_fd;
	uint64_t event_notifier_token;
	uint8_t capture_buf[CAPTURE_BUFFER_SIZE];
	struct lttng_msgpack_writer writer;
	bool has_captures;
};

static
int capture_enum(struct lttng_msgpack_writer *writer,
		struct lttng_interpreter_output *output)
{
	int ret;

	ret = lttng_msgpack_begin_map(writer, 2);
	if (ret) {
		goto end;
	}
	ret = lttng_msgpack_write_str(writer, "type");
	if (ret) {
		goto end;
	}
	ret = lttng_msgpack_write_str(writer, "enum");
	if (ret) {
		goto end;
	}
	ret = lttng_msgpack_write_str(writer, "value");
	if (ret) {
		goto end;
	}

	switch (output->type) {
	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
		ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
		if (ret) {
			goto end;
		}
		break;
	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
		ret = lttng_msgpack_write_signed_integer(writer, output->u.u);
		if (ret) {
			goto end;
		}
		break;
	default:
		CRIT("Unknown enum output type\n");
		ret = -1;
		goto end;
	}

	ret = lttng_msgpack_end_map(writer);
end:
	return ret;
}

static
int64_t capture_sequence_element_signed(uint8_t *ptr,
		const struct lttng_ust_type_integer *integer_type)
{
	int64_t value;
	unsigned int size = integer_type->size;
	bool byte_order_reversed = integer_type->reverse_byte_order;

	switch (size) {
	case 8:
		value = *ptr;
		break;
	case 16:
	{
		int16_t tmp;
		tmp = *(int16_t *) ptr;
		if (byte_order_reversed)
			tmp = lttng_ust_bswap_16(tmp);

		value = tmp;
		break;
	}
	case 32:
	{
		int32_t tmp;
		tmp = *(int32_t *) ptr;
		if (byte_order_reversed)
			tmp = lttng_ust_bswap_32(tmp);

		value = tmp;
		break;
	}
	case 64:
	{
		int64_t tmp;
		tmp = *(int64_t *) ptr;
		if (byte_order_reversed)
			tmp = lttng_ust_bswap_64(tmp);

		value = tmp;
		break;
	}
	default:
		CRIT("Unknown sequence element size\n");
		value = 0;
	}

	return value;
}

static
uint64_t capture_sequence_element_unsigned(uint8_t *ptr,
		const struct lttng_ust_type_integer *integer_type)
{
	uint64_t value;
	unsigned int size = integer_type->size;
	bool byte_order_reversed = integer_type->reverse_byte_order;

	switch (size) {
	case 8:
		value = *ptr;
		break;
	case 16:
	{
		uint16_t tmp;
		tmp = *(uint16_t *) ptr;
		if (byte_order_reversed)
			tmp = lttng_ust_bswap_16(tmp);

		value = tmp;
		break;
	}
	case 32:
	{
		uint32_t tmp;
		tmp = *(uint32_t *) ptr;
		if (byte_order_reversed)
			tmp = lttng_ust_bswap_32(tmp);

		value = tmp;
		break;
	}
	case 64:
	{
		uint64_t tmp;
		tmp = *(uint64_t *) ptr;
		if (byte_order_reversed)
			tmp = lttng_ust_bswap_64(tmp);

		value = tmp;
		break;
	}
	default:
		CRIT("Unknown sequence element size\n");
		value = 0;
	}

	return value;
}

static
int capture_sequence(struct lttng_msgpack_writer *writer,
		struct lttng_interpreter_output *output)
{
	const struct lttng_ust_type_integer *integer_type;
	const struct lttng_ust_type_common *nested_type;
	uint8_t *ptr;
	bool signedness;
	int i, ret;

	ret = lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem);
	if (ret) {
		goto end;
	}
	ptr = (uint8_t *) output->u.sequence.ptr;
	nested_type = output->u.sequence.nested_type;
	switch (nested_type->type) {
	case lttng_ust_type_integer:
		integer_type = lttng_ust_get_type_integer(nested_type);
		break;
	case lttng_ust_type_enum:
		/* Treat enumeration as an integer. */
		integer_type = lttng_ust_get_type_integer(lttng_ust_get_type_enum(nested_type)->container_type);
		break;
	default:
		CRIT("Capture of array of non-integer are not supported\n");
		ret = -1;
		goto end;
	}
	signedness = integer_type->signedness;
	for (i = 0; i < output->u.sequence.nr_elem; i++) {
		if (signedness) {
			ret = lttng_msgpack_write_signed_integer(writer,
				capture_sequence_element_signed(ptr, integer_type));
		} else {
			ret = lttng_msgpack_write_unsigned_integer(writer,
				capture_sequence_element_unsigned(ptr, integer_type));
		}
		if (ret) {
			goto end;
		}

		/*
		 * We assume that alignment is smaller or equal to the size.
		 * This currently holds true but if it changes in the future,
		 * we will want to change the pointer arithmetic below to
		 * take into account that the next element might be further
		 * away.
		 */
		assert(integer_type->alignment <= integer_type->size);

		/* Size is in number of bits. */
		ptr += (integer_type->size / CHAR_BIT) ;
	}

	ret = lttng_msgpack_end_array(writer);
end:
	return ret;
}

static
int notification_init(struct lttng_event_notifier_notification *notif,
		const struct lttng_ust_event_notifier *event_notifier)
{
	struct lttng_msgpack_writer *writer = &notif->writer;
	int ret = 0;

	notif->event_notifier_token = event_notifier->priv->parent.user_token;
	notif->notification_fd = event_notifier->priv->group->notification_fd;
	notif->has_captures = false;

	if (event_notifier->priv->num_captures > 0) {
		lttng_msgpack_writer_init(writer, notif->capture_buf,
				CAPTURE_BUFFER_SIZE);

		ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
		if (ret) {
			goto end;
		}
		notif->has_captures = true;
	}
end:
	return ret;
}

static
int notification_append_capture(
		struct lttng_event_notifier_notification *notif,
		struct lttng_interpreter_output *output)
{
	struct lttng_msgpack_writer *writer = &notif->writer;
	int ret;

	switch (output->type) {
	case LTTNG_INTERPRETER_TYPE_S64:
		ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
		break;
	case LTTNG_INTERPRETER_TYPE_U64:
		ret = lttng_msgpack_write_unsigned_integer(writer, output->u.u);
		break;
	case LTTNG_INTERPRETER_TYPE_DOUBLE:
		ret = lttng_msgpack_write_double(writer, output->u.d);
		break;
	case LTTNG_INTERPRETER_TYPE_STRING:
		ret = lttng_msgpack_write_str(writer, output->u.str.str);
		break;
	case LTTNG_INTERPRETER_TYPE_SEQUENCE:
		ret = capture_sequence(writer, output);
		break;
	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
		ret = capture_enum(writer, output);
		break;
	default:
		CRIT("Unknown capture output type\n");
		ret = -1;
	}
	return ret;
}

static
int notification_append_empty_capture(
		struct lttng_event_notifier_notification *notif)
{
	return lttng_msgpack_write_nil(&notif->writer);
}

static void record_error(const struct lttng_ust_event_notifier *event_notifier)
{
	struct lttng_event_notifier_group *event_notifier_group =
			event_notifier->priv->group;
	struct lttng_counter *error_counter;
	size_t dimension_index[1];
	int ret;

	error_counter = CMM_LOAD_SHARED(event_notifier_group->error_counter);
	/*
	 * load-acquire paired with store-release orders creation of the
	 * error counter and setting error_counter_len before the
	 * error_counter is used.
	 * Currently a full memory barrier is used, which could be
	 * turned into acquire-release barriers.
	 */
	cmm_smp_mb();
	/* This group may not have an error counter attached to it. */
	if (!error_counter)
		return;

	dimension_index[0] = event_notifier->priv->error_counter_index;
	ret = event_notifier_group->error_counter->ops->counter_add(
			error_counter->counter, dimension_index, 1);
	if (ret)
		WARN_ON_ONCE(1);
}

static
void notification_send(struct lttng_event_notifier_notification *notif,
		const struct lttng_ust_event_notifier *event_notifier)
{
	ssize_t ret;
	size_t content_len;
	int iovec_count = 1;
	struct lttng_ust_abi_event_notifier_notification ust_notif = {0};
	struct iovec iov[2];

	assert(notif);

	ust_notif.token = event_notifier->priv->parent.user_token;

	/*
	 * Prepare sending the notification from multiple buffers using an
	 * array of `struct iovec`. The first buffer of the vector is
	 * notification structure itself and is always present.
	 */
	iov[0].iov_base = &ust_notif;
	iov[0].iov_len = sizeof(ust_notif);

	if (notif->has_captures) {
		/*
		 * If captures were requested, the second buffer of the array
		 * is the capture buffer.
		 */
		assert(notif->writer.buffer);
		content_len = notif->writer.write_pos - notif->writer.buffer;

		assert(content_len > 0 && content_len <= CAPTURE_BUFFER_SIZE);

		iov[1].iov_base = notif->capture_buf;
		iov[1].iov_len = content_len;

		iovec_count++;
	} else {
		content_len = 0;
	}

	/*
	 * Update the capture buffer size so that receiver of the buffer will
	 * know how much to expect.
	 */
	ust_notif.capture_buf_size = content_len;

	/* Send all the buffers. */
	ret = ust_patient_writev(notif->notification_fd, iov, iovec_count);
	if (ret == -1) {
		if (errno == EAGAIN) {
			record_error(event_notifier);
			DBG("Cannot send event_notifier notification without blocking: %s",
				strerror(errno));
		} else {
			DBG("Error to sending event notifier notification: %s",
				strerror(errno));
			abort();
		}
	}
}

/*
 * Validate that the buffer has enough room to hold empty capture fields.
 */
static
bool validate_buffer_len(struct lttng_event_notifier_notification *notif, size_t captures_left)
{
	if (notif->writer.end_write_pos - notif->writer.write_pos < MSG_WRITE_NIL_LEN * captures_left)
		return false;
	return true;
}

void lttng_event_notifier_notification_send(
		const struct lttng_ust_event_notifier *event_notifier,
		const char *stack_data,
		struct lttng_ust_probe_ctx *probe_ctx,
		struct lttng_ust_notification_ctx *notif_ctx)
{
	/*
	 * This function is called from the probe, we must do dynamic
	 * allocation in this context.
	 */
	struct lttng_event_notifier_notification notif = {0};
	size_t captures_left;

	if (notification_init(&notif, event_notifier))
		goto error;

	captures_left = event_notifier->priv->num_captures;
	if (!validate_buffer_len(&notif, captures_left))
		goto error;

	if (caa_unlikely(notif_ctx->eval_capture)) {
		struct lttng_ust_bytecode_runtime *capture_bc_runtime;

		/*
		 * Iterate over all the capture bytecodes. If the interpreter
		 * functions returns successfully, append the value of the
		 * `output` parameter to the capture buffer. If the interpreter
		 * fails, append an empty capture to the buffer.
		 */
		cds_list_for_each_entry_rcu(capture_bc_runtime,
				&event_notifier->priv->capture_bytecode_runtime_head, node) {
			struct lttng_interpreter_output output;
			uint8_t *save_pos;
			int ret = -1;

			lttng_msgpack_save_writer_pos(&notif.writer, &save_pos);
			if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
					stack_data, probe_ctx, &output) == LTTNG_UST_BYTECODE_INTERPRETER_OK)
				ret = notification_append_capture(&notif, &output);
			if (ret || !validate_buffer_len(&notif, captures_left)) {
				/*
				 * On append capture error or if the generated
				 * buffer data would not leave enough room to
				 * write empty capture fields for the remaining
				 * fields, skip the field capture by restoring
				 * the msgpack writer position and writing an
				 * empty capture field.
				 */
				lttng_msgpack_restore_writer_pos(&notif.writer, save_pos);
				ret = notification_append_empty_capture(&notif);
				if (ret)
					CRIT("Not enough space for empty capture field\n");
			}
		}
	}

	if (notif.has_captures && lttng_msgpack_end_array(&notif.writer))
		goto error;

	/*
	 * Send the notification (including the capture buffer) to the
	 * sessiond.
	 */
	notification_send(&notif, event_notifier);
	return;

error:
	record_error(event_notifier);
	return;
}
Commit	Line	Data
d8d2416d	1	/*
c0c0989a	2	* SPDX-License-Identifier: LGPL-2.1-only
d8d2416d FD	3	*
d8d2416d FD	4	* Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
d8d2416d FD	5	*/
	6
	7	#define _LGPL_SOURCE
	8
b9f82a28	9	#include <assert.h>
d8d2416d	10	#include <errno.h>
9af5d97a MJ	11	#include <limits.h>
9af5d97a MJ	12
f03092d7	13	#include <lttng/ust-endian.h>
9d315d6d	14	#include "common/logging.h"
a2e4d05e	15	#include <urcu/rculist.h>
d8d2416d	16
4b4a1337	17	#include "lttng-tracer-core.h"
36c52fff	18	#include "lib/lttng-ust/events.h"
c3ba99c2	19	#include "common/msgpack/msgpack.h"
b9f82a28	20	#include "lttng-bytecode.h"
9d315d6d	21	#include "common/patient.h"
d8d2416d	22
d37ecb3f FD	23	/*
	24	* We want this write to be atomic AND non-blocking, meaning that we
	25	* want to write either everything OR nothing.
	26	* According to `pipe(7)`, writes that are less than `PIPE_BUF` bytes must be
	27	* atomic, so we bound the capture buffer size to the `PIPE_BUF` minus the size
	28	* of the notification struct we are sending alongside the capture buffer.
	29	*/
	30	#define CAPTURE_BUFFER_SIZE \
fd17d7ce	31	(PIPE_BUF - sizeof(struct lttng_ust_abi_event_notifier_notification) - 1)
d37ecb3f	32
65c955a5 MD	33	#define MSG_WRITE_NIL_LEN 1
65c955a5 MD	34
d37ecb3f FD	35	struct lttng_event_notifier_notification {
	36	int notification_fd;
	37	uint64_t event_notifier_token;
	38	uint8_t capture_buf[CAPTURE_BUFFER_SIZE];
	39	struct lttng_msgpack_writer writer;
	40	bool has_captures;
	41	};
	42
b9f82a28	43	static
c651e872	44	int capture_enum(struct lttng_msgpack_writer *writer,
b9f82a28 FD	45	struct lttng_interpreter_output *output)
b9f82a28 FD	46	{
c651e872	47	int ret;
b9f82a28	48
c651e872 MD	49	ret = lttng_msgpack_begin_map(writer, 2);
	50	if (ret) {
	51	goto end;
	52	}
	53	ret = lttng_msgpack_write_str(writer, "type");
	54	if (ret) {
	55	goto end;
	56	}
	57	ret = lttng_msgpack_write_str(writer, "enum");
	58	if (ret) {
	59	goto end;
	60	}
	61	ret = lttng_msgpack_write_str(writer, "value");
	62	if (ret) {
	63	goto end;
	64	}
b9f82a28 FD	65
	66	switch (output->type) {
	67	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
c651e872 MD	68	ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
	69	if (ret) {
	70	goto end;
	71	}
b9f82a28 FD	72	break;
b9f82a28 FD	73	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
c651e872 MD	74	ret = lttng_msgpack_write_signed_integer(writer, output->u.u);
	75	if (ret) {
	76	goto end;
	77	}
b9f82a28 FD	78	break;
b9f82a28 FD	79	default:
c651e872 MD	80	CRIT("Unknown enum output type\n");
	81	ret = -1;
	82	goto end;
b9f82a28 FD	83	}
b9f82a28 FD	84
c651e872 MD	85	ret = lttng_msgpack_end_map(writer);
	86	end:
	87	return ret;
b9f82a28 FD	88	}
	89
	90	static
	91	int64_t capture_sequence_element_signed(uint8_t *ptr,
4e48b5d2	92	const struct lttng_ust_type_integer *integer_type)
b9f82a28 FD	93	{
b9f82a28 FD	94	int64_t value;
a084756d MD	95	unsigned int size = integer_type->size;
a084756d MD	96	bool byte_order_reversed = integer_type->reverse_byte_order;
b9f82a28 FD	97
	98	switch (size) {
	99	case 8:
	100	value = *ptr;
	101	break;
	102	case 16:
	103	{
	104	int16_t tmp;
	105	tmp = (int16_t ) ptr;
	106	if (byte_order_reversed)
baa8acf3	107	tmp = lttng_ust_bswap_16(tmp);
b9f82a28 FD	108
	109	value = tmp;
	110	break;
	111	}
	112	case 32:
	113	{
	114	int32_t tmp;
	115	tmp = (int32_t ) ptr;
	116	if (byte_order_reversed)
baa8acf3	117	tmp = lttng_ust_bswap_32(tmp);
b9f82a28 FD	118
	119	value = tmp;
	120	break;
	121	}
	122	case 64:
	123	{
	124	int64_t tmp;
	125	tmp = (int64_t ) ptr;
	126	if (byte_order_reversed)
baa8acf3	127	tmp = lttng_ust_bswap_64(tmp);
b9f82a28 FD	128
	129	value = tmp;
	130	break;
	131	}
	132	default:
c651e872 MD	133	CRIT("Unknown sequence element size\n");
c651e872 MD	134	value = 0;
b9f82a28 FD	135	}
	136
	137	return value;
	138	}
	139
	140	static
	141	uint64_t capture_sequence_element_unsigned(uint8_t *ptr,
4e48b5d2	142	const struct lttng_ust_type_integer *integer_type)
b9f82a28 FD	143	{
b9f82a28 FD	144	uint64_t value;
a084756d MD	145	unsigned int size = integer_type->size;
a084756d MD	146	bool byte_order_reversed = integer_type->reverse_byte_order;
b9f82a28 FD	147
	148	switch (size) {
	149	case 8:
	150	value = *ptr;
	151	break;
	152	case 16:
	153	{
	154	uint16_t tmp;
	155	tmp = (uint16_t ) ptr;
	156	if (byte_order_reversed)
baa8acf3	157	tmp = lttng_ust_bswap_16(tmp);
b9f82a28 FD	158
	159	value = tmp;
	160	break;
	161	}
	162	case 32:
	163	{
	164	uint32_t tmp;
	165	tmp = (uint32_t ) ptr;
	166	if (byte_order_reversed)
baa8acf3	167	tmp = lttng_ust_bswap_32(tmp);
b9f82a28 FD	168
	169	value = tmp;
	170	break;
	171	}
	172	case 64:
	173	{
	174	uint64_t tmp;
	175	tmp = (uint64_t ) ptr;
	176	if (byte_order_reversed)
baa8acf3	177	tmp = lttng_ust_bswap_64(tmp);
b9f82a28 FD	178
	179	value = tmp;
	180	break;
	181	}
	182	default:
c651e872 MD	183	CRIT("Unknown sequence element size\n");
c651e872 MD	184	value = 0;
b9f82a28 FD	185	}
	186
	187	return value;
	188	}
	189
b9f82a28	190	static
c651e872	191	int capture_sequence(struct lttng_msgpack_writer *writer,
b9f82a28 FD	192	struct lttng_interpreter_output *output)
b9f82a28 FD	193	{
4e48b5d2 MD	194	const struct lttng_ust_type_integer *integer_type;
4e48b5d2 MD	195	const struct lttng_ust_type_common *nested_type;
b9f82a28 FD	196	uint8_t *ptr;
b9f82a28 FD	197	bool signedness;
c651e872	198	int i, ret;
b9f82a28	199
c651e872 MD	200	ret = lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem);
	201	if (ret) {
	202	goto end;
	203	}
b9f82a28 FD	204	ptr = (uint8_t *) output->u.sequence.ptr;
b9f82a28 FD	205	nested_type = output->u.sequence.nested_type;
a084756d MD	206	switch (nested_type->type) {
	207	case lttng_ust_type_integer:
	208	integer_type = lttng_ust_get_type_integer(nested_type);
b9f82a28	209	break;
a084756d	210	case lttng_ust_type_enum:
b9f82a28	211	/* Treat enumeration as an integer. */
a084756d	212	integer_type = lttng_ust_get_type_integer(lttng_ust_get_type_enum(nested_type)->container_type);
b9f82a28 FD	213	break;
b9f82a28 FD	214	default:
c651e872 MD	215	CRIT("Capture of array of non-integer are not supported\n");
	216	ret = -1;
	217	goto end;
b9f82a28 FD	218	}
	219	signedness = integer_type->signedness;
	220	for (i = 0; i < output->u.sequence.nr_elem; i++) {
	221	if (signedness) {
c651e872	222	ret = lttng_msgpack_write_signed_integer(writer,
b9f82a28 FD	223	capture_sequence_element_signed(ptr, integer_type));
b9f82a28 FD	224	} else {
c651e872	225	ret = lttng_msgpack_write_unsigned_integer(writer,
b9f82a28 FD	226	capture_sequence_element_unsigned(ptr, integer_type));
b9f82a28 FD	227	}
c651e872 MD	228	if (ret) {
	229	goto end;
	230	}
b9f82a28 FD	231
	232	/*
	233	* We assume that alignment is smaller or equal to the size.
	234	* This currently holds true but if it changes in the future,
2fbda51c	235	* we will want to change the pointer arithmetic below to
b9f82a28 FD	236	* take into account that the next element might be further
	237	* away.
	238	*/
	239	assert(integer_type->alignment <= integer_type->size);
	240
	241	/* Size is in number of bits. */
	242	ptr += (integer_type->size / CHAR_BIT) ;
	243	}
	244
c651e872 MD	245	ret = lttng_msgpack_end_array(writer);
	246	end:
	247	return ret;
b9f82a28 FD	248	}
b9f82a28 FD	249
d37ecb3f	250	static
c651e872	251	int notification_init(struct lttng_event_notifier_notification *notif,
cda77256	252	const struct lttng_ust_event_notifier *event_notifier)
d8d2416d	253	{
d37ecb3f	254	struct lttng_msgpack_writer *writer = &notif->writer;
c651e872	255	int ret = 0;
d37ecb3f	256
115db533 MD	257	notif->event_notifier_token = event_notifier->priv->parent.user_token;
115db533 MD	258	notif->notification_fd = event_notifier->priv->group->notification_fd;
d37ecb3f FD	259	notif->has_captures = false;
d37ecb3f FD	260
115db533	261	if (event_notifier->priv->num_captures > 0) {
d37ecb3f FD	262	lttng_msgpack_writer_init(writer, notif->capture_buf,
	263	CAPTURE_BUFFER_SIZE);
	264
c651e872 MD	265	ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
	266	if (ret) {
	267	goto end;
	268	}
d37ecb3f FD	269	notif->has_captures = true;
d37ecb3f FD	270	}
c651e872 MD	271	end:
c651e872 MD	272	return ret;
d37ecb3f FD	273	}
	274
	275	static
c651e872	276	int notification_append_capture(
d37ecb3f FD	277	struct lttng_event_notifier_notification *notif,
	278	struct lttng_interpreter_output *output)
	279	{
	280	struct lttng_msgpack_writer *writer = &notif->writer;
c651e872	281	int ret;
d37ecb3f FD	282
	283	switch (output->type) {
	284	case LTTNG_INTERPRETER_TYPE_S64:
c651e872	285	ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
d37ecb3f FD	286	break;
d37ecb3f FD	287	case LTTNG_INTERPRETER_TYPE_U64:
c651e872	288	ret = lttng_msgpack_write_unsigned_integer(writer, output->u.u);
d37ecb3f FD	289	break;
d37ecb3f FD	290	case LTTNG_INTERPRETER_TYPE_DOUBLE:
c651e872	291	ret = lttng_msgpack_write_double(writer, output->u.d);
d37ecb3f FD	292	break;
d37ecb3f FD	293	case LTTNG_INTERPRETER_TYPE_STRING:
c651e872	294	ret = lttng_msgpack_write_str(writer, output->u.str.str);
d37ecb3f FD	295	break;
d37ecb3f FD	296	case LTTNG_INTERPRETER_TYPE_SEQUENCE:
c651e872	297	ret = capture_sequence(writer, output);
d37ecb3f FD	298	break;
	299	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
	300	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
c651e872	301	ret = capture_enum(writer, output);
d37ecb3f FD	302	break;
d37ecb3f FD	303	default:
c651e872 MD	304	CRIT("Unknown capture output type\n");
c651e872 MD	305	ret = -1;
d37ecb3f	306	}
c651e872	307	return ret;
d37ecb3f FD	308	}
	309
	310	static
c651e872	311	int notification_append_empty_capture(
d37ecb3f FD	312	struct lttng_event_notifier_notification *notif)
d37ecb3f FD	313	{
c651e872	314	return lttng_msgpack_write_nil(&notif->writer);
d37ecb3f FD	315	}
d37ecb3f FD	316
cda77256	317	static void record_error(const struct lttng_ust_event_notifier *event_notifier)
6566528b FD	318	{
6566528b FD	319	struct lttng_event_notifier_group *event_notifier_group =
115db533	320	event_notifier->priv->group;
33f43caa	321	struct lttng_counter *error_counter;
6566528b FD	322	size_t dimension_index[1];
	323	int ret;
	324
33f43caa MD	325	error_counter = CMM_LOAD_SHARED(event_notifier_group->error_counter);
	326	/*
	327	* load-acquire paired with store-release orders creation of the
	328	* error counter and setting error_counter_len before the
	329	* error_counter is used.
	330	* Currently a full memory barrier is used, which could be
	331	* turned into acquire-release barriers.
	332	*/
	333	cmm_smp_mb();
c30ad764	334	/* This group may not have an error counter attached to it. */
33f43caa	335	if (!error_counter)
c30ad764 MD	336	return;
c30ad764 MD	337
115db533	338	dimension_index[0] = event_notifier->priv->error_counter_index;
6566528b	339	ret = event_notifier_group->error_counter->ops->counter_add(
33f43caa	340	error_counter->counter, dimension_index, 1);
6566528b FD	341	if (ret)
	342	WARN_ON_ONCE(1);
	343	}
	344
d37ecb3f	345	static
6566528b	346	void notification_send(struct lttng_event_notifier_notification *notif,
cda77256	347	const struct lttng_ust_event_notifier *event_notifier)
d37ecb3f FD	348	{
	349	ssize_t ret;
	350	size_t content_len;
	351	int iovec_count = 1;
fd17d7ce	352	struct lttng_ust_abi_event_notifier_notification ust_notif = {0};
d37ecb3f FD	353	struct iovec iov[2];
	354
	355	assert(notif);
	356
115db533	357	ust_notif.token = event_notifier->priv->parent.user_token;
d37ecb3f	358
d8d2416d	359	/*
d37ecb3f FD	360	* Prepare sending the notification from multiple buffers using an
	361	* array of `struct iovec`. The first buffer of the vector is
	362	* notification structure itself and is always present.
d8d2416d	363	*/
d37ecb3f FD	364	iov[0].iov_base = &ust_notif;
	365	iov[0].iov_len = sizeof(ust_notif);
	366
	367	if (notif->has_captures) {
	368	/*
	369	* If captures were requested, the second buffer of the array
	370	* is the capture buffer.
	371	*/
	372	assert(notif->writer.buffer);
	373	content_len = notif->writer.write_pos - notif->writer.buffer;
d8d2416d	374
d37ecb3f	375	assert(content_len > 0 && content_len <= CAPTURE_BUFFER_SIZE);
d8d2416d	376
d37ecb3f FD	377	iov[1].iov_base = notif->capture_buf;
	378	iov[1].iov_len = content_len;
	379
	380	iovec_count++;
	381	} else {
	382	content_len = 0;
	383	}
	384
	385	/*
	386	* Update the capture buffer size so that receiver of the buffer will
	387	* know how much to expect.
	388	*/
	389	ust_notif.capture_buf_size = content_len;
d8d2416d	390
d37ecb3f	391	/* Send all the buffers. */
516d12da	392	ret = ust_patient_writev(notif->notification_fd, iov, iovec_count);
d8d2416d FD	393	if (ret == -1) {
d8d2416d FD	394	if (errno == EAGAIN) {
6566528b FD	395	record_error(event_notifier);
6566528b FD	396	DBG("Cannot send event_notifier notification without blocking: %s",
d8d2416d FD	397	strerror(errno));
	398	} else {
	399	DBG("Error to sending event notifier notification: %s",
	400	strerror(errno));
	401	abort();
	402	}
	403	}
	404	}
d37ecb3f	405
65c955a5 MD	406	/*
	407	* Validate that the buffer has enough room to hold empty capture fields.
	408	*/
	409	static
	410	bool validate_buffer_len(struct lttng_event_notifier_notification *notif, size_t captures_left)
	411	{
	412	if (notif->writer.end_write_pos - notif->writer.write_pos < MSG_WRITE_NIL_LEN * captures_left)
	413	return false;
	414	return true;
	415	}
	416
6566528b	417	void lttng_event_notifier_notification_send(
cda77256	418	const struct lttng_ust_event_notifier *event_notifier,
a2e4d05e	419	const char *stack_data,
b2e37d27	420	struct lttng_ust_probe_ctx *probe_ctx,
a2e4d05e	421	struct lttng_ust_notification_ctx *notif_ctx)
d37ecb3f FD	422	{
	423	/*
	424	* This function is called from the probe, we must do dynamic
	425	* allocation in this context.
	426	*/
	427	struct lttng_event_notifier_notification notif = {0};
65c955a5	428	size_t captures_left;
d37ecb3f	429
65c955a5 MD	430	if (notification_init(&notif, event_notifier))
	431	goto error;
	432
	433	captures_left = event_notifier->priv->num_captures;
	434	if (!validate_buffer_len(&notif, captures_left))
	435	goto error;
d37ecb3f	436
a2e4d05e	437	if (caa_unlikely(notif_ctx->eval_capture)) {
5469a374	438	struct lttng_ust_bytecode_runtime *capture_bc_runtime;
d37ecb3f FD	439
	440	/*
	441	* Iterate over all the capture bytecodes. If the interpreter
	442	* functions returns successfully, append the value of the
	443	* `output` parameter to the capture buffer. If the interpreter
	444	* fails, append an empty capture to the buffer.
	445	*/
a2e4d05e MD	446	cds_list_for_each_entry_rcu(capture_bc_runtime,
a2e4d05e MD	447	&event_notifier->priv->capture_bytecode_runtime_head, node) {
d37ecb3f	448	struct lttng_interpreter_output output;
c651e872	449	uint8_t *save_pos;
65c955a5	450	int ret = -1;
d37ecb3f	451
c651e872	452	lttng_msgpack_save_writer_pos(&notif.writer, &save_pos);
22c30e27	453	if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
b2e37d27	454	stack_data, probe_ctx, &output) == LTTNG_UST_BYTECODE_INTERPRETER_OK)
c651e872	455	ret = notification_append_capture(&notif, &output);
65c955a5	456	if (ret \|\| !validate_buffer_len(&notif, captures_left)) {
c651e872	457	/*
65c955a5 MD	458	* On append capture error or if the generated
	459	* buffer data would not leave enough room to
	460	* write empty capture fields for the remaining
	461	* fields, skip the field capture by restoring
	462	* the msgpack writer position and writing an
	463	* empty capture field.
c651e872 MD	464	*/
c651e872 MD	465	lttng_msgpack_restore_writer_pos(&notif.writer, save_pos);
65c955a5 MD	466	ret = notification_append_empty_capture(&notif);
	467	if (ret)
	468	CRIT("Not enough space for empty capture field\n");
c651e872	469	}
d37ecb3f FD	470	}
	471	}
	472
65c955a5 MD	473	if (notif.has_captures && lttng_msgpack_end_array(&notif.writer))
	474	goto error;
	475
d37ecb3f FD	476	/*
	477	* Send the notification (including the capture buffer) to the
	478	* sessiond.
	479	*/
6566528b	480	notification_send(&notif, event_notifier);
65c955a5 MD	481	return;
	482
	483	error:
	484	record_error(event_notifier);
c651e872	485	return;
d37ecb3f	486	}