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

/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
 *
 * lttng-event-notifier-notification.c
 *
 * Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
 */

#include <linux/bug.h>

#include <lttng/lttng-bytecode.h>
#include <lttng/events.h>
#include <lttng/msgpack.h>
#include <lttng/event-notifier-notification.h>
#include <lttng/events-internal.h>
#include <lttng/probe-user.h>
#include <wrapper/barrier.h>

/*
 * The capture buffer size needs to be below 1024 bytes to avoid the
 * frame to be larger than the 1024 limit enforced by the kernel. If we
 * ever need to increase it, we will need to use a memory allocation
 * scheme which allows allocating temporary memory chunks from the
 * instrumentation sites. This could be done by adapting lttng
 * tp-mempool to become nmi-safe and lock-free.
 */
#define CAPTURE_BUFFER_SIZE 512

#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;

	/*
	 * Enums are captured as a map containing 2 key-value pairs. Such as:
	 * - type: enum
	 *   value: 177
	 */
	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:
		WARN_ON_ONCE(1);
	}

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

static
int64_t capture_sequence_element_signed(uint8_t *ptr,
		const struct lttng_kernel_type_integer *type)
{
	int64_t value = 0;
	unsigned int size = type->size;
	bool user = type->user;
	bool byte_order_reversed = type->reverse_byte_order;

	switch (size) {
	case 8:
	{
		int8_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int8_t)))
				tmp = 0;
		} else {
			tmp = *ptr;
		}
		value = tmp;
		break;
	}
	case 16:
	{
		int16_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int16_t)))
				tmp = 0;
		} else {
			tmp = *(int16_t *) ptr;
		}
		if (byte_order_reversed)
			__swab16s(&tmp);
		value = tmp;
		break;
	}
	case 32:
	{
		int32_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int32_t)))
				tmp = 0;
		} else {
			tmp = *(int32_t *) ptr;
		}
		if (byte_order_reversed)
			__swab32s(&tmp);
		value = tmp;
		break;
	}
	case 64:
	{
		int64_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int64_t)))
				tmp = 0;
		} else {
			tmp = *(int64_t *) ptr;
		}
		if (byte_order_reversed)
			__swab64s(&tmp);
		value = tmp;
		break;
	}
	default:
		WARN_ON_ONCE(1);
	}

	return value;
}

static
uint64_t capture_sequence_element_unsigned(uint8_t *ptr,
		const struct lttng_kernel_type_integer *type)
{
	uint64_t value = 0;
	unsigned int size = type->size;
	bool user = type->user;
	bool byte_order_reversed = type->reverse_byte_order;

	switch (size) {
	case 8:
	{
		uint8_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint8_t)))
				tmp = 0;
		} else {
			tmp = *ptr;
		}
		value = tmp;
		break;
	}
	case 16:
	{
		uint16_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint16_t)))
				tmp = 0;
		} else {
			tmp = *(uint16_t *) ptr;
		}
		if (byte_order_reversed)
			__swab16s(&tmp);
		value = tmp;
		break;
	}
	case 32:
	{
		uint32_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint32_t)))
				tmp = 0;
		} else {
			tmp = *(uint32_t *) ptr;
		}
		if (byte_order_reversed)
			__swab32s(&tmp);
		value = tmp;
		break;
	}
	case 64:
	{
		uint64_t tmp;

		if (user) {
			if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint64_t)))
				tmp = 0;
		} else {
			tmp = *(uint64_t *) ptr;
		}
		if (byte_order_reversed)
			__swab64s(&tmp);
		value = tmp;
		break;
	}
	default:
		WARN_ON_ONCE(1);
	}

	return value;
}

int capture_sequence(struct lttng_msgpack_writer *writer,
		struct lttng_interpreter_output *output)
{
	const struct lttng_kernel_type_integer *integer_type = NULL;
	const struct lttng_kernel_type_common *nested_type;
	uint8_t *ptr;
	bool signedness;
	int ret, i;

	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_kernel_type_integer:
		integer_type = lttng_kernel_get_type_integer(nested_type);
		break;
	case lttng_kernel_type_enum:
		/* Treat enumeration as an integer. */
		integer_type = lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type)->container_type);
		break;
	default:
		/* Capture of array of non-integer are not supported. */
		WARN_ON_ONCE(1);
		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));
			if (ret) {
				goto end;
			}
		} 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 arithmetics below to
		 * take into account that the next element might be further
		 * away.
		 */
		WARN_ON_ONCE(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_append_capture(
		struct lttng_event_notifier_notification *notif,
		struct lttng_interpreter_output *output)
{
	struct lttng_msgpack_writer *writer = &notif->writer;
	int ret = 0;

	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_STRING:
		if (output->u.str.user) {
			ret = lttng_msgpack_write_user_str(writer, output->u.str.user_str);
		} else {
			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:
		ret = -1;
		WARN_ON_ONCE(1);
	}
	return ret;
}

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

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

	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
void record_error(struct lttng_kernel_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;

	/*
	 * lttng_smp_load_acquire paired with lttng_smp_store_release orders
	 * creation of the error counter and setting error_counter_len
	 * before the error_counter is used.
	 */
	error_counter = lttng_smp_load_acquire(&event_notifier_group->error_counter);
	/* 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 = 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,
		struct lttng_kernel_event_notifier *event_notifier)
{
	struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
	struct lttng_kernel_ring_buffer_ctx ctx;
	struct lttng_kernel_abi_event_notifier_notification kernel_notif;
	size_t capture_buffer_content_len, reserve_size;
	int ret;

	reserve_size = sizeof(kernel_notif);
	kernel_notif.token = event_notifier->priv->parent.user_token;

	if (notif->has_captures) {
		capture_buffer_content_len = notif->writer.write_pos - notif->writer.buffer;
	} else {
		capture_buffer_content_len = 0;
	}

	WARN_ON_ONCE(capture_buffer_content_len > CAPTURE_BUFFER_SIZE);

	reserve_size += capture_buffer_content_len;
	kernel_notif.capture_buf_size = capture_buffer_content_len;

	lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, reserve_size,
			lttng_alignof(kernel_notif), NULL);
	ret = event_notifier_group->ops->event_reserve(&ctx);
	if (ret < 0) {
		record_error(event_notifier);
		return;
	}

	/* Write the notif structure. */
	event_notifier_group->ops->event_write(&ctx, &kernel_notif,
			sizeof(kernel_notif), lttng_alignof(kernel_notif));

	/*
	 * Write the capture buffer. No need to realigned as the below is a raw
	 * char* buffer.
	 */
	event_notifier_group->ops->event_write(&ctx, &notif->capture_buf,
			capture_buffer_content_len, 1);

	event_notifier_group->ops->event_commit(&ctx);
	irq_work_queue(&event_notifier_group->wakeup_pending);
}

/*
 * 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(struct lttng_kernel_event_notifier *event_notifier,
		const char *stack_data,
		struct lttng_kernel_probe_ctx *probe_ctx,
		struct lttng_kernel_notification_ctx *notif_ctx)
{
	struct lttng_event_notifier_notification notif = { 0 };
	size_t captures_left;

	if (unlikely(!READ_ONCE(event_notifier->parent.enabled)))
		return;

	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 (unlikely(notif_ctx->eval_capture)) {
		struct lttng_kernel_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.
		 */
		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);
			captures_left--;
			if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
					stack_data, probe_ctx, &output) == LTTNG_KERNEL_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);
				WARN_ON_ONCE(ret);
			}
		}
	}

	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
21f58fb7 FD	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
	2	*
	3	* lttng-event-notifier-notification.c
	4	*
	5	* Copyright (C) 2020 Francis Deslauriers <francis.deslauriers@efficios.com>
	6	*/
	7
42f3ef8c FD	8	#include <linux/bug.h>
	9
	10	#include <lttng/lttng-bytecode.h>
21f58fb7	11	#include <lttng/events.h>
42f3ef8c	12	#include <lttng/msgpack.h>
21f58fb7	13	#include <lttng/event-notifier-notification.h>
437d5aa5	14	#include <lttng/events-internal.h>
11b589f6	15	#include <lttng/probe-user.h>
6657edec	16	#include <wrapper/barrier.h>
21f58fb7	17
99d223ad	18	/*
e699ee6c MD	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.
99d223ad FD	25	*/
	26	#define CAPTURE_BUFFER_SIZE 512
	27
f125ded4 MD	28	#define MSG_WRITE_NIL_LEN 1
f125ded4 MD	29
99d223ad FD	30	struct lttng_event_notifier_notification {
	31	int notification_fd;
	32	uint64_t event_notifier_token;
	33	uint8_t capture_buf[CAPTURE_BUFFER_SIZE];
	34	struct lttng_msgpack_writer writer;
	35	bool has_captures;
	36	};
	37
42f3ef8c FD	38	static
	39	int capture_enum(struct lttng_msgpack_writer *writer,
	40	struct lttng_interpreter_output *output)
	41	{
	42	int ret;
	43
	44	/*
	45	* Enums are captured as a map containing 2 key-value pairs. Such as:
	46	* - type: enum
	47	* value: 177
	48	*/
	49	ret = lttng_msgpack_begin_map(writer, 2);
	50	if (ret) {
42f3ef8c FD	51	goto end;
	52	}
	53
	54	ret = lttng_msgpack_write_str(writer, "type");
	55	if (ret) {
42f3ef8c FD	56	goto end;
	57	}
	58
	59	ret = lttng_msgpack_write_str(writer, "enum");
	60	if (ret) {
42f3ef8c FD	61	goto end;
	62	}
	63
	64	ret = lttng_msgpack_write_str(writer, "value");
	65	if (ret) {
42f3ef8c FD	66	goto end;
	67	}
	68
	69	switch (output->type) {
	70	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
	71	ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
	72	if (ret) {
42f3ef8c FD	73	goto end;
	74	}
	75	break;
	76	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
	77	ret = lttng_msgpack_write_signed_integer(writer, output->u.u);
	78	if (ret) {
42f3ef8c FD	79	goto end;
	80	}
	81	break;
	82	default:
736f2dd6	83	WARN_ON_ONCE(1);
42f3ef8c FD	84	}
	85
	86	ret = lttng_msgpack_end_map(writer);
42f3ef8c FD	87	end:
	88	return ret;
	89	}
	90
	91	static
	92	int64_t capture_sequence_element_signed(uint8_t *ptr,
437d5aa5	93	const struct lttng_kernel_type_integer *type)
42f3ef8c FD	94	{
	95	int64_t value = 0;
	96	unsigned int size = type->size;
11b589f6	97	bool user = type->user;
42f3ef8c FD	98	bool byte_order_reversed = type->reverse_byte_order;
	99
	100	switch (size) {
	101	case 8:
11b589f6 MD	102	{
	103	int8_t tmp;
	104
	105	if (user) {
	106	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int8_t)))
	107	tmp = 0;
	108	} else {
	109	tmp = *ptr;
	110	}
	111	value = tmp;
42f3ef8c	112	break;
11b589f6	113	}
42f3ef8c FD	114	case 16:
	115	{
	116	int16_t tmp;
11b589f6 MD	117
	118	if (user) {
	119	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int16_t)))
	120	tmp = 0;
	121	} else {
	122	tmp = (int16_t ) ptr;
	123	}
42f3ef8c FD	124	if (byte_order_reversed)
42f3ef8c FD	125	__swab16s(&tmp);
42f3ef8c FD	126	value = tmp;
	127	break;
	128	}
	129	case 32:
	130	{
	131	int32_t tmp;
11b589f6 MD	132
	133	if (user) {
	134	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int32_t)))
	135	tmp = 0;
	136	} else {
	137	tmp = (int32_t ) ptr;
	138	}
42f3ef8c FD	139	if (byte_order_reversed)
42f3ef8c FD	140	__swab32s(&tmp);
42f3ef8c FD	141	value = tmp;
	142	break;
	143	}
	144	case 64:
	145	{
	146	int64_t tmp;
11b589f6 MD	147
	148	if (user) {
	149	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(int64_t)))
	150	tmp = 0;
	151	} else {
	152	tmp = (int64_t ) ptr;
	153	}
42f3ef8c FD	154	if (byte_order_reversed)
42f3ef8c FD	155	__swab64s(&tmp);
42f3ef8c FD	156	value = tmp;
	157	break;
	158	}
	159	default:
736f2dd6	160	WARN_ON_ONCE(1);
42f3ef8c FD	161	}
	162
	163	return value;
	164	}
	165
	166	static
	167	uint64_t capture_sequence_element_unsigned(uint8_t *ptr,
437d5aa5	168	const struct lttng_kernel_type_integer *type)
42f3ef8c FD	169	{
	170	uint64_t value = 0;
	171	unsigned int size = type->size;
11b589f6	172	bool user = type->user;
42f3ef8c FD	173	bool byte_order_reversed = type->reverse_byte_order;
	174
	175	switch (size) {
	176	case 8:
11b589f6 MD	177	{
	178	uint8_t tmp;
	179
	180	if (user) {
	181	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint8_t)))
	182	tmp = 0;
	183	} else {
	184	tmp = *ptr;
	185	}
	186	value = tmp;
42f3ef8c	187	break;
11b589f6	188	}
42f3ef8c FD	189	case 16:
	190	{
	191	uint16_t tmp;
11b589f6 MD	192
	193	if (user) {
	194	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint16_t)))
	195	tmp = 0;
	196	} else {
	197	tmp = (uint16_t ) ptr;
	198	}
42f3ef8c FD	199	if (byte_order_reversed)
42f3ef8c FD	200	__swab16s(&tmp);
42f3ef8c FD	201	value = tmp;
	202	break;
	203	}
	204	case 32:
	205	{
	206	uint32_t tmp;
11b589f6 MD	207
	208	if (user) {
	209	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint32_t)))
	210	tmp = 0;
	211	} else {
	212	tmp = (uint32_t ) ptr;
	213	}
42f3ef8c FD	214	if (byte_order_reversed)
42f3ef8c FD	215	__swab32s(&tmp);
42f3ef8c FD	216	value = tmp;
	217	break;
	218	}
	219	case 64:
	220	{
	221	uint64_t tmp;
11b589f6 MD	222
	223	if (user) {
	224	if (lttng_copy_from_user_check_nofault(&tmp, ptr, sizeof(uint64_t)))
	225	tmp = 0;
	226	} else {
	227	tmp = (uint64_t ) ptr;
	228	}
42f3ef8c FD	229	if (byte_order_reversed)
42f3ef8c FD	230	__swab64s(&tmp);
42f3ef8c FD	231	value = tmp;
	232	break;
	233	}
	234	default:
736f2dd6	235	WARN_ON_ONCE(1);
42f3ef8c FD	236	}
	237
	238	return value;
	239	}
	240
42f3ef8c FD	241	int capture_sequence(struct lttng_msgpack_writer *writer,
	242	struct lttng_interpreter_output *output)
	243	{
437d5aa5 MD	244	const struct lttng_kernel_type_integer *integer_type = NULL;
437d5aa5 MD	245	const struct lttng_kernel_type_common *nested_type;
42f3ef8c FD	246	uint8_t *ptr;
	247	bool signedness;
	248	int ret, i;
	249
	250	ret = lttng_msgpack_begin_array(writer, output->u.sequence.nr_elem);
	251	if (ret) {
42f3ef8c FD	252	goto end;
	253	}
	254
	255	ptr = (uint8_t *) output->u.sequence.ptr;
	256	nested_type = output->u.sequence.nested_type;
12bb2edb MD	257	switch (nested_type->type) {
12bb2edb MD	258	case lttng_kernel_type_integer:
437d5aa5	259	integer_type = lttng_kernel_get_type_integer(nested_type);
42f3ef8c	260	break;
437d5aa5	261	case lttng_kernel_type_enum:
42f3ef8c	262	/* Treat enumeration as an integer. */
437d5aa5	263	integer_type = lttng_kernel_get_type_integer(lttng_kernel_get_type_enum(nested_type)->container_type);
42f3ef8c FD	264	break;
	265	default:
	266	/* Capture of array of non-integer are not supported. */
736f2dd6 MD	267	WARN_ON_ONCE(1);
	268	ret = -1;
	269	goto end;
42f3ef8c FD	270	}
	271	signedness = integer_type->signedness;
	272	for (i = 0; i < output->u.sequence.nr_elem; i++) {
	273	if (signedness) {
	274	ret = lttng_msgpack_write_signed_integer(writer,
	275	capture_sequence_element_signed(ptr, integer_type));
	276	if (ret) {
42f3ef8c FD	277	goto end;
	278	}
	279	} else {
	280	ret = lttng_msgpack_write_unsigned_integer(writer,
	281	capture_sequence_element_unsigned(ptr, integer_type));
	282	if (ret) {
42f3ef8c FD	283	goto end;
	284	}
	285	}
	286
	287	/*
	288	* We assume that alignment is smaller or equal to the size.
	289	* This currently holds true but if it changes in the future,
	290	* we will want to change the pointer arithmetics below to
	291	* take into account that the next element might be further
	292	* away.
	293	*/
736f2dd6	294	WARN_ON_ONCE(integer_type->alignment > integer_type->size);
42f3ef8c FD	295
	296	/* Size is in number of bits. */
	297	ptr += (integer_type->size / CHAR_BIT) ;
	298	}
	299
	300	ret = lttng_msgpack_end_array(writer);
42f3ef8c FD	301	end:
	302	return ret;
	303	}
	304
99d223ad FD	305	static
	306	int notification_append_capture(
	307	struct lttng_event_notifier_notification *notif,
	308	struct lttng_interpreter_output *output)
	309	{
	310	struct lttng_msgpack_writer *writer = &notif->writer;
	311	int ret = 0;
	312
	313	switch (output->type) {
	314	case LTTNG_INTERPRETER_TYPE_S64:
	315	ret = lttng_msgpack_write_signed_integer(writer, output->u.s);
99d223ad FD	316	break;
	317	case LTTNG_INTERPRETER_TYPE_U64:
	318	ret = lttng_msgpack_write_unsigned_integer(writer, output->u.u);
99d223ad FD	319	break;
99d223ad FD	320	case LTTNG_INTERPRETER_TYPE_STRING:
8915cf5e MD	321	if (output->u.str.user) {
	322	ret = lttng_msgpack_write_user_str(writer, output->u.str.user_str);
	323	} else {
	324	ret = lttng_msgpack_write_str(writer, output->u.str.str);
	325	}
99d223ad FD	326	break;
	327	case LTTNG_INTERPRETER_TYPE_SEQUENCE:
	328	ret = capture_sequence(writer, output);
99d223ad FD	329	break;
	330	case LTTNG_INTERPRETER_TYPE_SIGNED_ENUM:
	331	case LTTNG_INTERPRETER_TYPE_UNSIGNED_ENUM:
	332	ret = capture_enum(writer, output);
99d223ad FD	333	break;
	334	default:
	335	ret = -1;
736f2dd6	336	WARN_ON_ONCE(1);
99d223ad	337	}
99d223ad FD	338	return ret;
	339	}
	340
	341	static
	342	int notification_append_empty_capture(
	343	struct lttng_event_notifier_notification *notif)
	344	{
736f2dd6	345	return lttng_msgpack_write_nil(&notif->writer);
99d223ad FD	346	}
	347
	348	static
	349	int notification_init(struct lttng_event_notifier_notification *notif,
a67ba386	350	struct lttng_kernel_event_notifier *event_notifier)
99d223ad FD	351	{
	352	struct lttng_msgpack_writer *writer = &notif->writer;
	353	int ret = 0;
	354
	355	notif->has_captures = false;
	356
a67ba386	357	if (event_notifier->priv->num_captures > 0) {
99d223ad FD	358	lttng_msgpack_writer_init(writer, notif->capture_buf,
	359	CAPTURE_BUFFER_SIZE);
	360
a67ba386	361	ret = lttng_msgpack_begin_array(writer, event_notifier->priv->num_captures);
99d223ad	362	if (ret) {
99d223ad FD	363	goto end;
	364	}
	365
	366	notif->has_captures = true;
	367	}
	368
	369	end:
	370	return ret;
	371	}
	372
99f52fcc	373	static
a67ba386	374	void record_error(struct lttng_kernel_event_notifier *event_notifier)
99f52fcc FD	375	{
99f52fcc FD	376
a67ba386	377	struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
ab04d7b1	378	struct lttng_counter *error_counter;
99f52fcc FD	379	size_t dimension_index[1];
	380	int ret;
	381
ab04d7b1	382	/*
6657edec	383	* lttng_smp_load_acquire paired with lttng_smp_store_release orders
ab04d7b1 MD	384	* creation of the error counter and setting error_counter_len
	385	* before the error_counter is used.
	386	*/
6657edec	387	error_counter = lttng_smp_load_acquire(&event_notifier_group->error_counter);
a83d6831	388	/* This group may not have an error counter attached to it. */
ab04d7b1	389	if (!error_counter)
a83d6831 FD	390	return;
a83d6831 FD	391
a67ba386	392	dimension_index[0] = event_notifier->priv->error_counter_index;
99f52fcc	393
ab04d7b1	394	ret = error_counter->ops->counter_add(error_counter->counter,
99f52fcc FD	395	dimension_index, 1);
	396	if (ret)
	397	WARN_ON_ONCE(1);
	398	}
	399
99d223ad FD	400	static
99d223ad FD	401	void notification_send(struct lttng_event_notifier_notification *notif,
a67ba386	402	struct lttng_kernel_event_notifier *event_notifier)
21f58fb7	403	{
a67ba386	404	struct lttng_event_notifier_group *event_notifier_group = event_notifier->priv->group;
8a57ec02	405	struct lttng_kernel_ring_buffer_ctx ctx;
606828e4	406	struct lttng_kernel_abi_event_notifier_notification kernel_notif;
99d223ad	407	size_t capture_buffer_content_len, reserve_size;
21f58fb7 FD	408	int ret;
21f58fb7 FD	409
99d223ad	410	reserve_size = sizeof(kernel_notif);
a67ba386	411	kernel_notif.token = event_notifier->priv->parent.user_token;
21f58fb7	412
99d223ad FD	413	if (notif->has_captures) {
	414	capture_buffer_content_len = notif->writer.write_pos - notif->writer.buffer;
	415	} else {
	416	capture_buffer_content_len = 0;
	417	}
	418
	419	WARN_ON_ONCE(capture_buffer_content_len > CAPTURE_BUFFER_SIZE);
	420
	421	reserve_size += capture_buffer_content_len;
	422	kernel_notif.capture_buf_size = capture_buffer_content_len;
	423
8a445457	424	lib_ring_buffer_ctx_init(&ctx, event_notifier_group->chan, reserve_size,
b1199bd3	425	lttng_alignof(kernel_notif), NULL);
c2fb9c1c	426	ret = event_notifier_group->ops->event_reserve(&ctx);
21f58fb7	427	if (ret < 0) {
99f52fcc	428	record_error(event_notifier);
21f58fb7 FD	429	return;
21f58fb7 FD	430	}
99d223ad	431
99d223ad FD	432	/* Write the notif structure. */
99d223ad FD	433	event_notifier_group->ops->event_write(&ctx, &kernel_notif,
f5ffbd77	434	sizeof(kernel_notif), lttng_alignof(kernel_notif));
99d223ad FD	435
	436	/*
	437	* Write the capture buffer. No need to realigned as the below is a raw
	438	* char* buffer.
	439	*/
	440	event_notifier_group->ops->event_write(&ctx, &notif->capture_buf,
f5ffbd77	441	capture_buffer_content_len, 1);
99d223ad	442
21f58fb7 FD	443	event_notifier_group->ops->event_commit(&ctx);
	444	irq_work_queue(&event_notifier_group->wakeup_pending);
	445	}
99d223ad	446
f125ded4 MD	447	/*
	448	* Validate that the buffer has enough room to hold empty capture fields.
	449	*/
	450	static
	451	bool validate_buffer_len(struct lttng_event_notifier_notification *notif, size_t captures_left)
	452	{
	453	if (notif->writer.end_write_pos - notif->writer.write_pos < MSG_WRITE_NIL_LEN * captures_left)
	454	return false;
	455	return true;
	456	}
	457
a67ba386	458	void lttng_event_notifier_notification_send(struct lttng_kernel_event_notifier *event_notifier,
c3eddb2e	459	const char *stack_data,
a92e844e	460	struct lttng_kernel_probe_ctx *probe_ctx,
a67ba386	461	struct lttng_kernel_notification_ctx *notif_ctx)
99d223ad FD	462	{
99d223ad FD	463	struct lttng_event_notifier_notification notif = { 0 };
f125ded4	464	size_t captures_left;
99d223ad	465
a67ba386	466	if (unlikely(!READ_ONCE(event_notifier->parent.enabled)))
99d223ad FD	467	return;
99d223ad FD	468
f125ded4 MD	469	if (notification_init(&notif, event_notifier))
	470	goto error;
	471
	472	captures_left = event_notifier->priv->num_captures;
	473	if (!validate_buffer_len(&notif, captures_left))
	474	goto error;
99d223ad	475
c3eddb2e	476	if (unlikely(notif_ctx->eval_capture)) {
218585b9	477	struct lttng_kernel_bytecode_runtime *capture_bc_runtime;
99d223ad FD	478
	479	/*
	480	* Iterate over all the capture bytecodes. If the interpreter
	481	* functions returns successfully, append the value of the
	482	* `output` parameter to the capture buffer. If the interpreter
	483	* fails, append an empty capture to the buffer.
	484	*/
c3eddb2e	485	list_for_each_entry_rcu(capture_bc_runtime,
a67ba386	486	&event_notifier->priv->capture_bytecode_runtime_head, node) {
99d223ad	487	struct lttng_interpreter_output output;
736f2dd6	488	uint8_t *save_pos;
f125ded4	489	int ret = -1;
99d223ad	490
736f2dd6	491	lttng_msgpack_save_writer_pos(&notif.writer, &save_pos);
f125ded4	492	captures_left--;
8a445457 MD	493	if (capture_bc_runtime->interpreter_func(capture_bc_runtime,
8a445457 MD	494	stack_data, probe_ctx, &output) == LTTNG_KERNEL_BYTECODE_INTERPRETER_OK)
99d223ad	495	ret = notification_append_capture(&notif, &output);
f125ded4	496	if (ret \|\| !validate_buffer_len(&notif, captures_left)) {
736f2dd6	497	/*
f125ded4 MD	498	* On append capture error or if the generated
	499	* buffer data would not leave enough room to
	500	* write empty capture fields for the remaining
	501	* fields, skip the field capture by restoring
	502	* the msgpack writer position and writing an
	503	* empty capture field.
736f2dd6 MD	504	*/
736f2dd6 MD	505	lttng_msgpack_restore_writer_pos(&notif.writer, save_pos);
f125ded4 MD	506	ret = notification_append_empty_capture(&notif);
f125ded4 MD	507	WARN_ON_ONCE(ret);
736f2dd6	508	}
99d223ad FD	509	}
	510	}
	511
f125ded4 MD	512	if (notif.has_captures && lttng_msgpack_end_array(&notif.writer))
	513	goto error;
	514
99d223ad FD	515	/*
	516	* Send the notification (including the capture buffer) to the
	517	* sessiond.
	518	*/
	519	notification_send(&notif, event_notifier);
f125ded4 MD	520	return;
	521
	522	error:
	523	record_error(event_notifier);
99d223ad FD	524	return;
99d223ad FD	525	}