[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_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);

/*
 * 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_call_key(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_call_variadic_key(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);
}

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