[libside.git] / src / side.c

// SPDX-License-Identifier: MIT
/*
 * Copyright 2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <side/trace.h>
#include <string.h>
#include <assert.h>

#include "rcu.h"
#include "list.h"

/* Top 8 bits reserved for kernel tracer use. */
#if SIDE_BITS_PER_LONG == 64
# define SIDE_EVENT_ENABLED_KERNEL_MASK			0xFF00000000000000ULL
# define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 	0x8000000000000000ULL

/* Allow 2^56 tracer references on an event. */
# define SIDE_EVENT_ENABLED_USER_MASK			0x00FFFFFFFFFFFFFFULL
#else
# define SIDE_EVENT_ENABLED_KERNEL_MASK			0xFF000000UL
# define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK	0x80000000UL

/* Allow 2^24 tracer references on an event. */
# define SIDE_EVENT_ENABLED_USER_MASK			0x00FFFFFFUL
#endif

struct side_events_register_handle {
	struct side_list_node node;
	struct side_event_description **events;
	uint32_t nr_events;
};

struct side_tracer_handle {
	struct side_list_node node;
	void (*cb)(enum side_tracer_notification notif,
		struct side_event_description **events, uint32_t nr_events, void *priv);
	void *priv;
};

struct side_statedump_request_handle {
	struct side_list_node node;
	void (*cb)(void);
};

struct side_callback {
	union {
		void (*call)(const struct side_event_description *desc,
			const struct side_arg_vec *side_arg_vec,
			void *priv);
		void (*call_variadic)(const struct side_event_description *desc,
			const struct side_arg_vec *side_arg_vec,
			const struct side_arg_dynamic_struct *var_struct,
			void *priv);
	} u;
	void *priv;
	void *key;
};

static struct side_rcu_gp_state rcu_gp;

/*
 * Lazy initialization for early use within library constructors.
 */
static bool initialized;
/*
 * Do not register/unregister any more events after destructor.
 */
static bool finalized;

/*
 * Recursive mutex to allow tracer callbacks to use the side API.
 */
static pthread_mutex_t side_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;

static DEFINE_SIDE_LIST_HEAD(side_events_list);
static DEFINE_SIDE_LIST_HEAD(side_tracer_list);
static DEFINE_SIDE_LIST_HEAD(side_statedump_list);

/*
 * Callback filter key for state dump.
 */
static __thread void *filter_key;

/*
 * The empty callback has a NULL function callback pointer, which stops
 * iteration on the array of callbacks immediately.
 */
const char side_empty_callback[sizeof(struct side_callback)];

static
void _side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec, void *key)
{
	struct side_rcu_read_state rcu_read_state;
	const struct side_event_state_0 *es0;
	const struct side_callback *side_cb;
	uintptr_t enabled;

	if (side_unlikely(finalized))
		return;
	if (side_unlikely(!initialized))
		side_init();
	if (side_unlikely(event_state->version != 0))
		abort();
	es0 = side_container_of(event_state, const struct side_event_state_0, parent);
	assert(!(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC));
	enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
	if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
		// TODO: call kernel write.
	}
	side_rcu_read_begin(&rcu_gp, &rcu_read_state);
	for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call != NULL; side_cb++) {
		/* A NULL key is always a match. */
		if (key && side_cb->key && side_cb->key != key)
			continue;
		side_cb->u.call(es0->desc, side_arg_vec, side_cb->priv);
	}
	side_rcu_read_end(&rcu_gp, &rcu_read_state);
}

void side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec)
{
	_side_call(event_state, side_arg_vec, NULL);
}

void side_statedump_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec)
{
	_side_call(event_state, side_arg_vec, filter_key);
}

static
void _side_call_variadic(const struct side_event_state *event_state,
	const struct side_arg_vec *side_arg_vec,
	const struct side_arg_dynamic_struct *var_struct,
	void *key)
{
	struct side_rcu_read_state rcu_read_state;
	const struct side_event_state_0 *es0;
	const struct side_callback *side_cb;
	uintptr_t enabled;

	if (side_unlikely(finalized))
		return;
	if (side_unlikely(!initialized))
		side_init();
	if (side_unlikely(event_state->version != 0))
		abort();
	es0 = side_container_of(event_state, const struct side_event_state_0, parent);
	assert(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC);
	enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
	if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
		// TODO: call kernel write.
	}
	side_rcu_read_begin(&rcu_gp, &rcu_read_state);
	for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call_variadic != NULL; side_cb++) {
		/* A NULL key is always a match. */
		if (key && side_cb->key && side_cb->key != key)
			continue;
		side_cb->u.call_variadic(es0->desc, side_arg_vec, var_struct, side_cb->priv);
	}
	side_rcu_read_end(&rcu_gp, &rcu_read_state);
}

void side_call_variadic(const struct side_event_state *event_state,
	const struct side_arg_vec *side_arg_vec,
	const struct side_arg_dynamic_struct *var_struct)
{
	_side_call_variadic(event_state, side_arg_vec, var_struct, NULL);
}

void side_statedump_call_variadic(const struct side_event_state *event_state,
	const struct side_arg_vec *side_arg_vec,
	const struct side_arg_dynamic_struct *var_struct)
{
	_side_call_variadic(event_state, side_arg_vec, var_struct, filter_key);
}

static
const struct side_callback *side_tracer_callback_lookup(
		const struct side_event_description *desc,
		void *call, void *priv, void *key)
{
	struct side_event_state *event_state = side_ptr_get(desc->state);
	const struct side_event_state_0 *es0;
	const struct side_callback *cb;

	if (side_unlikely(event_state->version != 0))
		abort();
	es0 = side_container_of(event_state, const struct side_event_state_0, parent);
	for (cb = es0->callbacks; cb->u.call != NULL; cb++) {
		if ((void *) cb->u.call == call && cb->priv == priv && cb->key == key)
			return cb;
	}
	return NULL;
}

static
int _side_tracer_callback_register(struct side_event_description *desc,
		void *call, void *priv, void *key)
{
	struct side_event_state *event_state;
	struct side_callback *old_cb, *new_cb;
	struct side_event_state_0 *es0;
	int ret = SIDE_ERROR_OK;
	uint32_t old_nr_cb;

	if (!call)
		return SIDE_ERROR_INVAL;
	if (finalized)
		return SIDE_ERROR_EXITING;
	if (!initialized)
		side_init();
	pthread_mutex_lock(&side_lock);
	event_state = side_ptr_get(desc->state);
	if (side_unlikely(event_state->version != 0))
		abort();
	es0 = side_container_of(event_state, struct side_event_state_0, parent);
	old_nr_cb = es0->nr_callbacks;
	if (old_nr_cb == UINT32_MAX) {
		ret = SIDE_ERROR_INVAL;
		goto unlock;
	}
	/* Reject duplicate (call, priv) tuples. */
	if (side_tracer_callback_lookup(desc, call, priv, key)) {
		ret = SIDE_ERROR_EXIST;
		goto unlock;
	}
	old_cb = (struct side_callback *) es0->callbacks;
	/* old_nr_cb + 1 (new cb) + 1 (NULL) */
	new_cb = (struct side_callback *) calloc(old_nr_cb + 2, sizeof(struct side_callback));
	if (!new_cb) {
		ret = SIDE_ERROR_NOMEM;
		goto unlock;
	}
	memcpy(new_cb, old_cb, old_nr_cb);
	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
		new_cb[old_nr_cb].u.call_variadic =
			(side_tracer_callback_variadic_func) call;
	else
		new_cb[old_nr_cb].u.call =
			(side_tracer_callback_func) call;
	new_cb[old_nr_cb].priv = priv;
	new_cb[old_nr_cb].key = key;
	/* High order bits are already zeroed. */
	side_rcu_assign_pointer(es0->callbacks, new_cb);
	side_rcu_wait_grace_period(&rcu_gp);
	if (old_nr_cb)
		free(old_cb);
	es0->nr_callbacks++;
	/* Increment concurrently with kernel setting the top bits. */
	if (!old_nr_cb)
		(void) __atomic_add_fetch(&es0->enabled, 1, __ATOMIC_RELAXED);
unlock:
	pthread_mutex_unlock(&side_lock);
	return ret;
}

int side_tracer_callback_register(struct side_event_description *desc,
		side_tracer_callback_func call,
		void *priv, void *key)
{
	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
		return SIDE_ERROR_INVAL;
	return _side_tracer_callback_register(desc, (void *) call, priv, key);
}

int side_tracer_callback_variadic_register(struct side_event_description *desc,
		side_tracer_callback_variadic_func call_variadic,
		void *priv, void *key)
{
	if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
		return SIDE_ERROR_INVAL;
	return _side_tracer_callback_register(desc, (void *) call_variadic, priv, key);
}

static int _side_tracer_callback_unregister(struct side_event_description *desc,
		void *call, void *priv, void *key)
{
	struct side_event_state *event_state;
	struct side_callback *old_cb, *new_cb;
	const struct side_callback *cb_pos;
	struct side_event_state_0 *es0;
	uint32_t pos_idx;
	int ret = SIDE_ERROR_OK;
	uint32_t old_nr_cb;

	if (!call)
		return SIDE_ERROR_INVAL;
	if (finalized)
		return SIDE_ERROR_EXITING;
	if (!initialized)
		side_init();
	pthread_mutex_lock(&side_lock);
	event_state = side_ptr_get(desc->state);
	if (side_unlikely(event_state->version != 0))
		abort();
	es0 = side_container_of(event_state, struct side_event_state_0, parent);
	cb_pos = side_tracer_callback_lookup(desc, call, priv, key);
	if (!cb_pos) {
		ret = SIDE_ERROR_NOENT;
		goto unlock;
	}
	old_nr_cb = es0->nr_callbacks;
	old_cb = (struct side_callback *) es0->callbacks;
	if (old_nr_cb == 1) {
		new_cb = (struct side_callback *) &side_empty_callback;
	} else {
		pos_idx = cb_pos - es0->callbacks;
		/* Remove entry at pos_idx. */
		/* old_nr_cb - 1 (removed cb) + 1 (NULL) */
		new_cb = (struct side_callback *) calloc(old_nr_cb, sizeof(struct side_callback));
		if (!new_cb) {
			ret = SIDE_ERROR_NOMEM;
			goto unlock;
		}
		memcpy(new_cb, old_cb, pos_idx);
		memcpy(&new_cb[pos_idx], &old_cb[pos_idx + 1], old_nr_cb - pos_idx - 1);
	}
	/* High order bits are already zeroed. */
	side_rcu_assign_pointer(es0->callbacks, new_cb);
	side_rcu_wait_grace_period(&rcu_gp);
	free(old_cb);
	es0->nr_callbacks--;
	/* Decrement concurrently with kernel setting the top bits. */
	if (old_nr_cb == 1)
		(void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
unlock:
	pthread_mutex_unlock(&side_lock);
	return ret;
}

int side_tracer_callback_unregister(struct side_event_description *desc,
		side_tracer_callback_func call,
		void *priv, void *key)
{
	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
		return SIDE_ERROR_INVAL;
	return _side_tracer_callback_unregister(desc, (void *) call, priv, key);
}

int side_tracer_callback_variadic_unregister(struct side_event_description *desc,
		side_tracer_callback_variadic_func call_variadic,
		void *priv, void *key)
{
	if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
		return SIDE_ERROR_INVAL;
	return _side_tracer_callback_unregister(desc, (void *) call_variadic, priv, key);
}

struct side_events_register_handle *side_events_register(struct side_event_description **events, uint32_t nr_events)
{
	struct side_events_register_handle *events_handle = NULL;
	struct side_tracer_handle *tracer_handle;

	if (finalized)
		return NULL;
	if (!initialized)
		side_init();
	events_handle = (struct side_events_register_handle *)
			calloc(1, sizeof(struct side_events_register_handle));
	if (!events_handle)
		return NULL;
	events_handle->events = events;
	events_handle->nr_events = nr_events;

	pthread_mutex_lock(&side_lock);
	side_list_insert_node_tail(&side_events_list, &events_handle->node);
	side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
		tracer_handle->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
			events, nr_events, tracer_handle->priv);
	}
	pthread_mutex_unlock(&side_lock);
	//TODO: call event batch register ioctl
	return events_handle;
}

static
void side_event_remove_callbacks(struct side_event_description *desc)
{
	struct side_event_state *event_state = side_ptr_get(desc->state);
	struct side_event_state_0 *es0;
	struct side_callback *old_cb;
	uint32_t nr_cb;

	if (side_unlikely(event_state->version != 0))
		abort();
	es0 = side_container_of(event_state, struct side_event_state_0, parent);
	nr_cb = es0->nr_callbacks;
	if (!nr_cb)
		return;
	old_cb = (struct side_callback *) es0->callbacks;
	(void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
	/*
	 * Setting the state back to 0 cb and empty callbacks out of
	 * caution. This should not matter because instrumentation is
	 * unreachable.
	 */
	es0->nr_callbacks = 0;
	side_rcu_assign_pointer(es0->callbacks, &side_empty_callback);
	/*
	 * No need to wait for grace period because instrumentation is
	 * unreachable.
	 */
	free(old_cb);
}

/*
 * Unregister event handle. At this point, all side events in that
 * handle should be unreachable.
 */
void side_events_unregister(struct side_events_register_handle *events_handle)
{
	struct side_tracer_handle *tracer_handle;
	uint32_t i;

	if (!events_handle)
		return;
	if (finalized)
		return;
	if (!initialized)
		side_init();
	pthread_mutex_lock(&side_lock);
	side_list_remove_node(&events_handle->node);
	side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
		tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS,
			events_handle->events, events_handle->nr_events,
			tracer_handle->priv);
	}
	for (i = 0; i < events_handle->nr_events; i++) {
		struct side_event_description *event = events_handle->events[i];

		/* Skip NULL pointers */
		if (!event)
			continue;
		side_event_remove_callbacks(event);
	}
	pthread_mutex_unlock(&side_lock);
	//TODO: call event batch unregister ioctl
	free(events_handle);
}

struct side_tracer_handle *side_tracer_event_notification_register(
		void (*cb)(enum side_tracer_notification notif,
			struct side_event_description **events, uint32_t nr_events, void *priv),
		void *priv)
{
	struct side_tracer_handle *tracer_handle;
	struct side_events_register_handle *events_handle;

	if (finalized)
		return NULL;
	if (!initialized)
		side_init();
	tracer_handle = (struct side_tracer_handle *)
				calloc(1, sizeof(struct side_tracer_handle));
	if (!tracer_handle)
		return NULL;
	pthread_mutex_lock(&side_lock);
	tracer_handle->cb = cb;
	tracer_handle->priv = priv;
	side_list_insert_node_tail(&side_tracer_list, &tracer_handle->node);
	side_list_for_each_entry(events_handle, &side_events_list, node) {
		cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
			events_handle->events, events_handle->nr_events, priv);
	}
	pthread_mutex_unlock(&side_lock);
	return tracer_handle;
}

void side_tracer_event_notification_unregister(struct side_tracer_handle *tracer_handle)
{
	struct side_events_register_handle *events_handle;

	if (finalized)
		return;
	if (!initialized)
		side_init();
	pthread_mutex_lock(&side_lock);
	side_list_for_each_entry(events_handle, &side_events_list, node) {
		tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS,
			events_handle->events, events_handle->nr_events,
			tracer_handle->priv);
	}
	side_list_remove_node(&tracer_handle->node);
	pthread_mutex_unlock(&side_lock);
	free(tracer_handle);
}

struct side_statedump_request_handle *side_statedump_request_notification_register(void (*statedump_cb)(void))
{
	struct side_statedump_request_handle *handle;

	if (finalized)
		return NULL;
	if (!initialized)
		side_init();
	/*
	 * The statedump request notification should not be registered
	 * from a notification callback.
	 */
	assert(filter_key == NULL);
	handle = (struct side_statedump_request_handle *)
				calloc(1, sizeof(struct side_statedump_request_handle));
	if (!handle)
		return NULL;
	pthread_mutex_lock(&side_lock);
	handle->cb = statedump_cb;
	side_list_insert_node_tail(&side_statedump_list, &handle->node);
	/* Invoke callback for all tracers. */
	statedump_cb();
	pthread_mutex_unlock(&side_lock);
	return handle;
}

void side_statedump_request_notification_unregister(struct side_statedump_request_handle *handle)
{
	if (finalized)
		return;
	if (!initialized)
		side_init();
	assert(filter_key == NULL);
	pthread_mutex_lock(&side_lock);
	side_list_remove_node(&handle->node);
	pthread_mutex_unlock(&side_lock);
	free(handle);
}

void side_tracer_statedump_request(void *key)
{
	struct side_statedump_request_handle *handle;

	/* Invoke the state dump callback specifically for the tracer key. */
	filter_key = key;
	pthread_mutex_lock(&side_lock);
	side_list_for_each_entry(handle, &side_statedump_list, node)
		handle->cb();
	pthread_mutex_unlock(&side_lock);
	filter_key = NULL;
}

void side_init(void)
{
	if (initialized)
		return;
	side_rcu_gp_init(&rcu_gp);
	initialized = true;
}

/*
 * side_exit() is executed from a library destructor. It can be called
 * explicitly at application exit as well. Concurrent side API use is
 * not expected at that point.
 */
void side_exit(void)
{
	struct side_events_register_handle *handle, *tmp;

	if (finalized)
		return;
	side_list_for_each_entry_safe(handle, tmp, &side_events_list, node)
		side_events_unregister(handle);
	side_rcu_gp_exit(&rcu_gp);
	finalized = true;
}
Commit	Line	Data
67337c4a MD	1	// SPDX-License-Identifier: MIT
	2	/*
	3	* Copyright 2022 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	4	*/
	5
	6	#include <side/trace.h>
	7	#include <string.h>
b1bf768c	8	#include <assert.h>
67337c4a MD	9
	10	#include "rcu.h"
	11	#include "list.h"
	12
	13	/* Top 8 bits reserved for kernel tracer use. */
	14	#if SIDE_BITS_PER_LONG == 64
	15	# define SIDE_EVENT_ENABLED_KERNEL_MASK 0xFF00000000000000ULL
	16	# define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 0x8000000000000000ULL
	17
	18	/* Allow 2^56 tracer references on an event. */
	19	# define SIDE_EVENT_ENABLED_USER_MASK 0x00FFFFFFFFFFFFFFULL
	20	#else
	21	# define SIDE_EVENT_ENABLED_KERNEL_MASK 0xFF000000UL
	22	# define SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK 0x80000000UL
	23
	24	/* Allow 2^24 tracer references on an event. */
	25	# define SIDE_EVENT_ENABLED_USER_MASK 0x00FFFFFFUL
	26	#endif
	27
	28	struct side_events_register_handle {
	29	struct side_list_node node;
	30	struct side_event_description **events;
	31	uint32_t nr_events;
	32	};
	33
	34	struct side_tracer_handle {
	35	struct side_list_node node;
	36	void (*cb)(enum side_tracer_notification notif,
	37	struct side_event_description *events, uint32_t nr_events, void priv);
	38	void *priv;
	39	};
	40
f0b01832 MD	41	struct side_statedump_request_handle {
	42	struct side_list_node node;
	43	void (*cb)(void);
	44	};
	45
867b4725 MD	46	struct side_callback {
	47	union {
	48	void (call)(const struct side_event_description desc,
	49	const struct side_arg_vec *side_arg_vec,
	50	void *priv);
	51	void (call_variadic)(const struct side_event_description desc,
	52	const struct side_arg_vec *side_arg_vec,
	53	const struct side_arg_dynamic_struct *var_struct,
	54	void *priv);
	55	} u;
	56	void *priv;
92c377f9	57	void *key;
867b4725 MD	58	};
867b4725 MD	59
67337c4a MD	60	static struct side_rcu_gp_state rcu_gp;
	61
	62	/*
	63	* Lazy initialization for early use within library constructors.
	64	*/
	65	static bool initialized;
	66	/*
	67	* Do not register/unregister any more events after destructor.
	68	*/
	69	static bool finalized;
	70
	71	/*
	72	* Recursive mutex to allow tracer callbacks to use the side API.
	73	*/
	74	static pthread_mutex_t side_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
	75
	76	static DEFINE_SIDE_LIST_HEAD(side_events_list);
	77	static DEFINE_SIDE_LIST_HEAD(side_tracer_list);
f0b01832	78	static DEFINE_SIDE_LIST_HEAD(side_statedump_list);
67337c4a	79
74be90b7 MD	80	/*
	81	* Callback filter key for state dump.
	82	*/
	83	static __thread void *filter_key;
	84
67337c4a MD	85	/*
	86	* The empty callback has a NULL function callback pointer, which stops
	87	* iteration on the array of callbacks immediately.
	88	*/
867b4725	89	const char side_empty_callback[sizeof(struct side_callback)];
67337c4a	90
74be90b7 MD	91	static
74be90b7 MD	92	void _side_call(const struct side_event_state event_state, const struct side_arg_vec side_arg_vec, void *key)
67337c4a MD	93	{
67337c4a MD	94	struct side_rcu_read_state rcu_read_state;
b2a84b9f	95	const struct side_event_state_0 *es0;
67337c4a MD	96	const struct side_callback *side_cb;
	97	uintptr_t enabled;
	98
	99	if (side_unlikely(finalized))
	100	return;
	101	if (side_unlikely(!initialized))
	102	side_init();
b2a84b9f MD	103	if (side_unlikely(event_state->version != 0))
b2a84b9f MD	104	abort();
49aea3ef	105	es0 = side_container_of(event_state, const struct side_event_state_0, parent);
7269a8a3	106	assert(!(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC));
b2a84b9f	107	enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
67337c4a MD	108	if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
	109	// TODO: call kernel write.
	110	}
	111	side_rcu_read_begin(&rcu_gp, &rcu_read_state);
92c377f9 MD	112	for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call != NULL; side_cb++) {
	113	/* A NULL key is always a match. */
	114	if (key && side_cb->key && side_cb->key != key)
	115	continue;
7269a8a3	116	side_cb->u.call(es0->desc, side_arg_vec, side_cb->priv);
92c377f9	117	}
67337c4a MD	118	side_rcu_read_end(&rcu_gp, &rcu_read_state);
	119	}
	120
92c377f9 MD	121	void side_call(const struct side_event_state event_state, const struct side_arg_vec side_arg_vec)
92c377f9 MD	122	{
74be90b7	123	_side_call(event_state, side_arg_vec, NULL);
92c377f9 MD	124	}
92c377f9 MD	125
f0b01832	126	void side_statedump_call(const struct side_event_state event_state, const struct side_arg_vec side_arg_vec)
74be90b7 MD	127	{
	128	_side_call(event_state, side_arg_vec, filter_key);
	129	}
	130
	131	static
	132	void _side_call_variadic(const struct side_event_state *event_state,
67337c4a	133	const struct side_arg_vec *side_arg_vec,
92c377f9 MD	134	const struct side_arg_dynamic_struct *var_struct,
92c377f9 MD	135	void *key)
67337c4a MD	136	{
67337c4a MD	137	struct side_rcu_read_state rcu_read_state;
b2a84b9f	138	const struct side_event_state_0 *es0;
67337c4a MD	139	const struct side_callback *side_cb;
	140	uintptr_t enabled;
	141
	142	if (side_unlikely(finalized))
	143	return;
	144	if (side_unlikely(!initialized))
	145	side_init();
b2a84b9f MD	146	if (side_unlikely(event_state->version != 0))
b2a84b9f MD	147	abort();
49aea3ef	148	es0 = side_container_of(event_state, const struct side_event_state_0, parent);
7269a8a3	149	assert(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC);
b2a84b9f	150	enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
67337c4a MD	151	if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
	152	// TODO: call kernel write.
	153	}
	154	side_rcu_read_begin(&rcu_gp, &rcu_read_state);
92c377f9 MD	155	for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call_variadic != NULL; side_cb++) {
	156	/* A NULL key is always a match. */
	157	if (key && side_cb->key && side_cb->key != key)
	158	continue;
7269a8a3	159	side_cb->u.call_variadic(es0->desc, side_arg_vec, var_struct, side_cb->priv);
92c377f9	160	}
67337c4a MD	161	side_rcu_read_end(&rcu_gp, &rcu_read_state);
	162	}
	163
92c377f9 MD	164	void side_call_variadic(const struct side_event_state *event_state,
	165	const struct side_arg_vec *side_arg_vec,
	166	const struct side_arg_dynamic_struct *var_struct)
	167	{
74be90b7 MD	168	_side_call_variadic(event_state, side_arg_vec, var_struct, NULL);
	169	}
	170
f0b01832	171	void side_statedump_call_variadic(const struct side_event_state *event_state,
74be90b7 MD	172	const struct side_arg_vec *side_arg_vec,
	173	const struct side_arg_dynamic_struct *var_struct)
	174	{
	175	_side_call_variadic(event_state, side_arg_vec, var_struct, filter_key);
92c377f9 MD	176	}
92c377f9 MD	177
67337c4a MD	178	static
	179	const struct side_callback *side_tracer_callback_lookup(
	180	const struct side_event_description *desc,
92c377f9	181	void call, void priv, void *key)
67337c4a	182	{
0b9e59d6	183	struct side_event_state *event_state = side_ptr_get(desc->state);
b2a84b9f	184	const struct side_event_state_0 *es0;
67337c4a MD	185	const struct side_callback *cb;
67337c4a MD	186
b2a84b9f MD	187	if (side_unlikely(event_state->version != 0))
b2a84b9f MD	188	abort();
49aea3ef	189	es0 = side_container_of(event_state, const struct side_event_state_0, parent);
7269a8a3	190	for (cb = es0->callbacks; cb->u.call != NULL; cb++) {
92c377f9	191	if ((void *) cb->u.call == call && cb->priv == priv && cb->key == key)
67337c4a MD	192	return cb;
	193	}
	194	return NULL;
	195	}
	196
	197	static
	198	int _side_tracer_callback_register(struct side_event_description *desc,
92c377f9	199	void call, void priv, void *key)
67337c4a	200	{
0b9e59d6	201	struct side_event_state *event_state;
67337c4a	202	struct side_callback old_cb, new_cb;
b2a84b9f	203	struct side_event_state_0 *es0;
67337c4a MD	204	int ret = SIDE_ERROR_OK;
	205	uint32_t old_nr_cb;
	206
	207	if (!call)
	208	return SIDE_ERROR_INVAL;
	209	if (finalized)
	210	return SIDE_ERROR_EXITING;
	211	if (!initialized)
	212	side_init();
	213	pthread_mutex_lock(&side_lock);
0b9e59d6	214	event_state = side_ptr_get(desc->state);
b2a84b9f MD	215	if (side_unlikely(event_state->version != 0))
b2a84b9f MD	216	abort();
49aea3ef	217	es0 = side_container_of(event_state, struct side_event_state_0, parent);
3cac1780	218	old_nr_cb = es0->nr_callbacks;
67337c4a MD	219	if (old_nr_cb == UINT32_MAX) {
	220	ret = SIDE_ERROR_INVAL;
	221	goto unlock;
	222	}
	223	/* Reject duplicate (call, priv) tuples. */
92c377f9	224	if (side_tracer_callback_lookup(desc, call, priv, key)) {
67337c4a MD	225	ret = SIDE_ERROR_EXIST;
	226	goto unlock;
	227	}
7269a8a3	228	old_cb = (struct side_callback *) es0->callbacks;
67337c4a MD	229	/* old_nr_cb + 1 (new cb) + 1 (NULL) */
	230	new_cb = (struct side_callback *) calloc(old_nr_cb + 2, sizeof(struct side_callback));
	231	if (!new_cb) {
	232	ret = SIDE_ERROR_NOMEM;
	233	goto unlock;
	234	}
	235	memcpy(new_cb, old_cb, old_nr_cb);
	236	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
	237	new_cb[old_nr_cb].u.call_variadic =
	238	(side_tracer_callback_variadic_func) call;
	239	else
	240	new_cb[old_nr_cb].u.call =
	241	(side_tracer_callback_func) call;
	242	new_cb[old_nr_cb].priv = priv;
92c377f9	243	new_cb[old_nr_cb].key = key;
f60d8121	244	/* High order bits are already zeroed. */
7269a8a3	245	side_rcu_assign_pointer(es0->callbacks, new_cb);
67337c4a MD	246	side_rcu_wait_grace_period(&rcu_gp);
	247	if (old_nr_cb)
	248	free(old_cb);
3cac1780	249	es0->nr_callbacks++;
67337c4a MD	250	/* Increment concurrently with kernel setting the top bits. */
67337c4a MD	251	if (!old_nr_cb)
b2a84b9f	252	(void) __atomic_add_fetch(&es0->enabled, 1, __ATOMIC_RELAXED);
67337c4a MD	253	unlock:
	254	pthread_mutex_unlock(&side_lock);
	255	return ret;
	256	}
	257
	258	int side_tracer_callback_register(struct side_event_description *desc,
	259	side_tracer_callback_func call,
92c377f9	260	void priv, void key)
67337c4a MD	261	{
	262	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
	263	return SIDE_ERROR_INVAL;
92c377f9	264	return _side_tracer_callback_register(desc, (void *) call, priv, key);
67337c4a MD	265	}
	266
	267	int side_tracer_callback_variadic_register(struct side_event_description *desc,
	268	side_tracer_callback_variadic_func call_variadic,
92c377f9	269	void priv, void key)
67337c4a MD	270	{
	271	if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
	272	return SIDE_ERROR_INVAL;
92c377f9	273	return _side_tracer_callback_register(desc, (void *) call_variadic, priv, key);
67337c4a MD	274	}
	275
	276	static int _side_tracer_callback_unregister(struct side_event_description *desc,
92c377f9	277	void call, void priv, void *key)
67337c4a	278	{
0b9e59d6	279	struct side_event_state *event_state;
67337c4a MD	280	struct side_callback old_cb, new_cb;
67337c4a MD	281	const struct side_callback *cb_pos;
b2a84b9f	282	struct side_event_state_0 *es0;
67337c4a MD	283	uint32_t pos_idx;
	284	int ret = SIDE_ERROR_OK;
	285	uint32_t old_nr_cb;
	286
	287	if (!call)
	288	return SIDE_ERROR_INVAL;
	289	if (finalized)
	290	return SIDE_ERROR_EXITING;
	291	if (!initialized)
	292	side_init();
	293	pthread_mutex_lock(&side_lock);
0b9e59d6	294	event_state = side_ptr_get(desc->state);
b2a84b9f MD	295	if (side_unlikely(event_state->version != 0))
b2a84b9f MD	296	abort();
49aea3ef	297	es0 = side_container_of(event_state, struct side_event_state_0, parent);
92c377f9	298	cb_pos = side_tracer_callback_lookup(desc, call, priv, key);
67337c4a MD	299	if (!cb_pos) {
	300	ret = SIDE_ERROR_NOENT;
	301	goto unlock;
	302	}
3cac1780	303	old_nr_cb = es0->nr_callbacks;
7269a8a3	304	old_cb = (struct side_callback *) es0->callbacks;
67337c4a MD	305	if (old_nr_cb == 1) {
	306	new_cb = (struct side_callback *) &side_empty_callback;
	307	} else {
7269a8a3	308	pos_idx = cb_pos - es0->callbacks;
67337c4a MD	309	/* Remove entry at pos_idx. */
	310	/* old_nr_cb - 1 (removed cb) + 1 (NULL) */
	311	new_cb = (struct side_callback *) calloc(old_nr_cb, sizeof(struct side_callback));
	312	if (!new_cb) {
	313	ret = SIDE_ERROR_NOMEM;
	314	goto unlock;
	315	}
	316	memcpy(new_cb, old_cb, pos_idx);
	317	memcpy(&new_cb[pos_idx], &old_cb[pos_idx + 1], old_nr_cb - pos_idx - 1);
	318	}
f60d8121	319	/* High order bits are already zeroed. */
7269a8a3	320	side_rcu_assign_pointer(es0->callbacks, new_cb);
67337c4a MD	321	side_rcu_wait_grace_period(&rcu_gp);
67337c4a MD	322	free(old_cb);
3cac1780	323	es0->nr_callbacks--;
67337c4a MD	324	/* Decrement concurrently with kernel setting the top bits. */
67337c4a MD	325	if (old_nr_cb == 1)
b2a84b9f	326	(void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
67337c4a MD	327	unlock:
	328	pthread_mutex_unlock(&side_lock);
	329	return ret;
	330	}
	331
	332	int side_tracer_callback_unregister(struct side_event_description *desc,
	333	side_tracer_callback_func call,
92c377f9	334	void priv, void key)
67337c4a MD	335	{
	336	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
	337	return SIDE_ERROR_INVAL;
92c377f9	338	return _side_tracer_callback_unregister(desc, (void *) call, priv, key);
67337c4a MD	339	}
	340
	341	int side_tracer_callback_variadic_unregister(struct side_event_description *desc,
	342	side_tracer_callback_variadic_func call_variadic,
92c377f9	343	void priv, void key)
67337c4a MD	344	{
	345	if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
	346	return SIDE_ERROR_INVAL;
92c377f9	347	return _side_tracer_callback_unregister(desc, (void *) call_variadic, priv, key);
67337c4a MD	348	}
	349
	350	struct side_events_register_handle side_events_register(struct side_event_description *events, uint32_t nr_events)
	351	{
	352	struct side_events_register_handle *events_handle = NULL;
	353	struct side_tracer_handle *tracer_handle;
	354
	355	if (finalized)
	356	return NULL;
	357	if (!initialized)
	358	side_init();
	359	events_handle = (struct side_events_register_handle *)
	360	calloc(1, sizeof(struct side_events_register_handle));
	361	if (!events_handle)
	362	return NULL;
	363	events_handle->events = events;
	364	events_handle->nr_events = nr_events;
	365
	366	pthread_mutex_lock(&side_lock);
	367	side_list_insert_node_tail(&side_events_list, &events_handle->node);
	368	side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
	369	tracer_handle->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
	370	events, nr_events, tracer_handle->priv);
	371	}
	372	pthread_mutex_unlock(&side_lock);
	373	//TODO: call event batch register ioctl
	374	return events_handle;
	375	}
	376
	377	static
	378	void side_event_remove_callbacks(struct side_event_description *desc)
	379	{
0b9e59d6	380	struct side_event_state *event_state = side_ptr_get(desc->state);
b2a84b9f	381	struct side_event_state_0 *es0;
67337c4a	382	struct side_callback *old_cb;
3cac1780	383	uint32_t nr_cb;
67337c4a	384
b2a84b9f MD	385	if (side_unlikely(event_state->version != 0))
b2a84b9f MD	386	abort();
49aea3ef	387	es0 = side_container_of(event_state, struct side_event_state_0, parent);
3cac1780 MD	388	nr_cb = es0->nr_callbacks;
	389	if (!nr_cb)
	390	return;
7269a8a3	391	old_cb = (struct side_callback *) es0->callbacks;
b2a84b9f	392	(void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
67337c4a MD	393	/*
	394	* Setting the state back to 0 cb and empty callbacks out of
	395	* caution. This should not matter because instrumentation is
	396	* unreachable.
	397	*/
3cac1780	398	es0->nr_callbacks = 0;
7269a8a3	399	side_rcu_assign_pointer(es0->callbacks, &side_empty_callback);
67337c4a MD	400	/*
	401	* No need to wait for grace period because instrumentation is
	402	* unreachable.
	403	*/
	404	free(old_cb);
	405	}
	406
	407	/*
	408	* Unregister event handle. At this point, all side events in that
	409	* handle should be unreachable.
	410	*/
	411	void side_events_unregister(struct side_events_register_handle *events_handle)
	412	{
	413	struct side_tracer_handle *tracer_handle;
	414	uint32_t i;
	415
	416	if (!events_handle)
	417	return;
	418	if (finalized)
	419	return;
	420	if (!initialized)
	421	side_init();
	422	pthread_mutex_lock(&side_lock);
	423	side_list_remove_node(&events_handle->node);
	424	side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
	425	tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS,
	426	events_handle->events, events_handle->nr_events,
	427	tracer_handle->priv);
	428	}
	429	for (i = 0; i < events_handle->nr_events; i++) {
	430	struct side_event_description *event = events_handle->events[i];
	431
	432	/* Skip NULL pointers */
	433	if (!event)
	434	continue;
	435	side_event_remove_callbacks(event);
	436	}
	437	pthread_mutex_unlock(&side_lock);
	438	//TODO: call event batch unregister ioctl
	439	free(events_handle);
	440	}
	441
	442	struct side_tracer_handle *side_tracer_event_notification_register(
	443	void (*cb)(enum side_tracer_notification notif,
	444	struct side_event_description *events, uint32_t nr_events, void priv),
	445	void *priv)
	446	{
	447	struct side_tracer_handle *tracer_handle;
	448	struct side_events_register_handle *events_handle;
	449
	450	if (finalized)
	451	return NULL;
	452	if (!initialized)
	453	side_init();
	454	tracer_handle = (struct side_tracer_handle *)
	455	calloc(1, sizeof(struct side_tracer_handle));
	456	if (!tracer_handle)
	457	return NULL;
	458	pthread_mutex_lock(&side_lock);
	459	tracer_handle->cb = cb;
	460	tracer_handle->priv = priv;
	461	side_list_insert_node_tail(&side_tracer_list, &tracer_handle->node);
	462	side_list_for_each_entry(events_handle, &side_events_list, node) {
	463	cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
464	events_handle->events, events_handle->nr_events, priv);
465	}
466	pthread_mutex_unlock(&side_lock);
467	return tracer_handle;
468	}
469
470	void side_tracer_event_notification_unregister(struct side_tracer_handle *tracer_handle)
471	{
472	struct side_events_register_handle *events_handle;
473
474	if (finalized)
475	return;
476	if (!initialized)
477	side_init();
478	pthread_mutex_lock(&side_lock);
479	side_list_for_each_entry(events_handle, &side_events_list, node) {
480	tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS,
481	events_handle->events, events_handle->nr_events,
482	tracer_handle->priv);
483	}
484	side_list_remove_node(&tracer_handle->node);
485	pthread_mutex_unlock(&side_lock);
be787080	486	free(tracer_handle);
67337c4a MD	487	}
67337c4a MD	488
f0b01832 MD	489	struct side_statedump_request_handle side_statedump_request_notification_register(void (statedump_cb)(void))
	490	{
	491	struct side_statedump_request_handle *handle;
	492
	493	if (finalized)
	494	return NULL;
	495	if (!initialized)
	496	side_init();
	497	/*
	498	* The statedump request notification should not be registered
	499	* from a notification callback.
	500	*/
	501	assert(filter_key == NULL);
	502	handle = (struct side_statedump_request_handle *)
	503	calloc(1, sizeof(struct side_statedump_request_handle));
	504	if (!handle)
	505	return NULL;
	506	pthread_mutex_lock(&side_lock);
	507	handle->cb = statedump_cb;
	508	side_list_insert_node_tail(&side_statedump_list, &handle->node);
	509	/* Invoke callback for all tracers. */
	510	statedump_cb();
	511	pthread_mutex_unlock(&side_lock);
	512	return handle;
	513	}
	514
	515	void side_statedump_request_notification_unregister(struct side_statedump_request_handle *handle)
	516	{
	517	if (finalized)
	518	return;
	519	if (!initialized)
	520	side_init();
	521	assert(filter_key == NULL);
	522	pthread_mutex_lock(&side_lock);
	523	side_list_remove_node(&handle->node);
	524	pthread_mutex_unlock(&side_lock);
	525	free(handle);
	526	}
	527
	528	void side_tracer_statedump_request(void *key)
	529	{
	530	struct side_statedump_request_handle *handle;
	531
	532	/* Invoke the state dump callback specifically for the tracer key. */
	533	filter_key = key;
	534	pthread_mutex_lock(&side_lock);
	535	side_list_for_each_entry(handle, &side_statedump_list, node)
	536	handle->cb();
	537	pthread_mutex_unlock(&side_lock);
	538	filter_key = NULL;
	539	}
	540
67337c4a MD	541	void side_init(void)
	542	{
	543	if (initialized)
	544	return;
	545	side_rcu_gp_init(&rcu_gp);
	546	initialized = true;
	547	}
	548
	549	/*
	550	* side_exit() is executed from a library destructor. It can be called
	551	* explicitly at application exit as well. Concurrent side API use is
	552	* not expected at that point.
	553	*/
	554	void side_exit(void)
	555	{
	556	struct side_events_register_handle handle, tmp;
	557
	558	if (finalized)
	559	return;
	560	side_list_for_each_entry_safe(handle, tmp, &side_events_list, node)
	561	side_events_unregister(handle);
	562	side_rcu_gp_exit(&rcu_gp);
	563	finalized = true;
	564	}