[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;
};

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);

/*
 * The empty callback has a NULL function callback pointer, which stops
 * iteration on the array of callbacks immediately.
 */
const struct side_callback side_empty_callback = { };

void side_call(const struct side_event_state *event_state, const struct side_arg_vec *side_arg_vec)
{
	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, p);
	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++)
		side_cb->u.call(es0->desc, side_arg_vec, 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)
{
	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, p);
	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++)
		side_cb->u.call_variadic(es0->desc, side_arg_vec, var_struct, side_cb->priv);
	side_rcu_read_end(&rcu_gp, &rcu_read_state);
}

static
const struct side_callback *side_tracer_callback_lookup(
		const struct side_event_description *desc,
		void *call, void *priv)
{
	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, p);
	for (cb = es0->callbacks; cb->u.call != NULL; cb++) {
		if ((void *) cb->u.call == call && cb->priv == priv)
			return cb;
	}
	return NULL;
}

static
int _side_tracer_callback_register(struct side_event_description *desc,
		void *call, void *priv)
{
	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, p);
	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)) {
		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;
	/* 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)
{
	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
		return SIDE_ERROR_INVAL;
	return _side_tracer_callback_register(desc, (void *) call, priv);
}

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

static int _side_tracer_callback_unregister(struct side_event_description *desc,
		void *call, void *priv)
{
	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, p);
	cb_pos = side_tracer_callback_lookup(desc, call, priv);
	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)
{
	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
		return SIDE_ERROR_INVAL;
	return _side_tracer_callback_unregister(desc, (void *) call, priv);
}

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

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, p);
	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
	41	static struct side_rcu_gp_state rcu_gp;
	42
	43	/*
	44	* Lazy initialization for early use within library constructors.
	45	*/
	46	static bool initialized;
	47	/*
	48	* Do not register/unregister any more events after destructor.
	49	*/
	50	static bool finalized;
	51
	52	/*
	53	* Recursive mutex to allow tracer callbacks to use the side API.
	54	*/
	55	static pthread_mutex_t side_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
	56
	57	static DEFINE_SIDE_LIST_HEAD(side_events_list);
	58	static DEFINE_SIDE_LIST_HEAD(side_tracer_list);
	59
	60	/*
	61	* The empty callback has a NULL function callback pointer, which stops
	62	* iteration on the array of callbacks immediately.
	63	*/
	64	const struct side_callback side_empty_callback = { };
	65
0d747f98	66	void side_call(const struct side_event_state event_state, const struct side_arg_vec side_arg_vec)
67337c4a MD	67	{
67337c4a MD	68	struct side_rcu_read_state rcu_read_state;
b2a84b9f	69	const struct side_event_state_0 *es0;
67337c4a MD	70	const struct side_callback *side_cb;
	71	uintptr_t enabled;
	72
	73	if (side_unlikely(finalized))
	74	return;
	75	if (side_unlikely(!initialized))
	76	side_init();
b2a84b9f MD	77	if (side_unlikely(event_state->version != 0))
	78	abort();
	79	es0 = side_container_of(event_state, const struct side_event_state_0, p);
7269a8a3	80	assert(!(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC));
b2a84b9f	81	enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
67337c4a MD	82	if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
	83	// TODO: call kernel write.
	84	}
	85	side_rcu_read_begin(&rcu_gp, &rcu_read_state);
7269a8a3 MD	86	for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call != NULL; side_cb++)
7269a8a3 MD	87	side_cb->u.call(es0->desc, side_arg_vec, side_cb->priv);
67337c4a MD	88	side_rcu_read_end(&rcu_gp, &rcu_read_state);
	89	}
	90
0d747f98	91	void side_call_variadic(const struct side_event_state *event_state,
67337c4a MD	92	const struct side_arg_vec *side_arg_vec,
	93	const struct side_arg_dynamic_struct *var_struct)
	94	{
	95	struct side_rcu_read_state rcu_read_state;
b2a84b9f	96	const struct side_event_state_0 *es0;
67337c4a MD	97	const struct side_callback *side_cb;
	98	uintptr_t enabled;
	99
	100	if (side_unlikely(finalized))
	101	return;
	102	if (side_unlikely(!initialized))
	103	side_init();
b2a84b9f MD	104	if (side_unlikely(event_state->version != 0))
	105	abort();
	106	es0 = side_container_of(event_state, const struct side_event_state_0, p);
7269a8a3	107	assert(es0->desc->flags & SIDE_EVENT_FLAG_VARIADIC);
b2a84b9f	108	enabled = __atomic_load_n(&es0->enabled, __ATOMIC_RELAXED);
67337c4a MD	109	if (side_unlikely(enabled & SIDE_EVENT_ENABLED_KERNEL_USER_EVENT_MASK)) {
	110	// TODO: call kernel write.
	111	}
	112	side_rcu_read_begin(&rcu_gp, &rcu_read_state);
7269a8a3 MD	113	for (side_cb = side_rcu_dereference(es0->callbacks); side_cb->u.call_variadic != NULL; side_cb++)
7269a8a3 MD	114	side_cb->u.call_variadic(es0->desc, side_arg_vec, var_struct, side_cb->priv);
67337c4a MD	115	side_rcu_read_end(&rcu_gp, &rcu_read_state);
	116	}
	117
	118	static
	119	const struct side_callback *side_tracer_callback_lookup(
	120	const struct side_event_description *desc,
	121	void call, void priv)
	122	{
0b9e59d6	123	struct side_event_state *event_state = side_ptr_get(desc->state);
b2a84b9f	124	const struct side_event_state_0 *es0;
67337c4a MD	125	const struct side_callback *cb;
67337c4a MD	126
b2a84b9f MD	127	if (side_unlikely(event_state->version != 0))
	128	abort();
	129	es0 = side_container_of(event_state, const struct side_event_state_0, p);
7269a8a3	130	for (cb = es0->callbacks; cb->u.call != NULL; cb++) {
67337c4a MD	131	if ((void *) cb->u.call == call && cb->priv == priv)
	132	return cb;
	133	}
	134	return NULL;
	135	}
	136
	137	static
	138	int _side_tracer_callback_register(struct side_event_description *desc,
	139	void call, void priv)
	140	{
0b9e59d6	141	struct side_event_state *event_state;
67337c4a	142	struct side_callback old_cb, new_cb;
b2a84b9f	143	struct side_event_state_0 *es0;
67337c4a MD	144	int ret = SIDE_ERROR_OK;
	145	uint32_t old_nr_cb;
	146
	147	if (!call)
	148	return SIDE_ERROR_INVAL;
	149	if (finalized)
	150	return SIDE_ERROR_EXITING;
	151	if (!initialized)
	152	side_init();
	153	pthread_mutex_lock(&side_lock);
0b9e59d6	154	event_state = side_ptr_get(desc->state);
b2a84b9f MD	155	if (side_unlikely(event_state->version != 0))
	156	abort();
	157	es0 = side_container_of(event_state, struct side_event_state_0, p);
3cac1780	158	old_nr_cb = es0->nr_callbacks;
67337c4a MD	159	if (old_nr_cb == UINT32_MAX) {
	160	ret = SIDE_ERROR_INVAL;
	161	goto unlock;
	162	}
	163	/* Reject duplicate (call, priv) tuples. */
	164	if (side_tracer_callback_lookup(desc, call, priv)) {
	165	ret = SIDE_ERROR_EXIST;
	166	goto unlock;
	167	}
7269a8a3	168	old_cb = (struct side_callback *) es0->callbacks;
67337c4a MD	169	/* old_nr_cb + 1 (new cb) + 1 (NULL) */
	170	new_cb = (struct side_callback *) calloc(old_nr_cb + 2, sizeof(struct side_callback));
	171	if (!new_cb) {
	172	ret = SIDE_ERROR_NOMEM;
	173	goto unlock;
	174	}
	175	memcpy(new_cb, old_cb, old_nr_cb);
	176	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
	177	new_cb[old_nr_cb].u.call_variadic =
	178	(side_tracer_callback_variadic_func) call;
	179	else
	180	new_cb[old_nr_cb].u.call =
	181	(side_tracer_callback_func) call;
	182	new_cb[old_nr_cb].priv = priv;
f60d8121	183	/* High order bits are already zeroed. */
7269a8a3	184	side_rcu_assign_pointer(es0->callbacks, new_cb);
67337c4a MD	185	side_rcu_wait_grace_period(&rcu_gp);
	186	if (old_nr_cb)
	187	free(old_cb);
3cac1780	188	es0->nr_callbacks++;
67337c4a MD	189	/* Increment concurrently with kernel setting the top bits. */
67337c4a MD	190	if (!old_nr_cb)
b2a84b9f	191	(void) __atomic_add_fetch(&es0->enabled, 1, __ATOMIC_RELAXED);
67337c4a MD	192	unlock:
	193	pthread_mutex_unlock(&side_lock);
	194	return ret;
	195	}
	196
	197	int side_tracer_callback_register(struct side_event_description *desc,
	198	side_tracer_callback_func call,
	199	void *priv)
	200	{
	201	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
	202	return SIDE_ERROR_INVAL;
	203	return _side_tracer_callback_register(desc, (void *) call, priv);
	204	}
	205
	206	int side_tracer_callback_variadic_register(struct side_event_description *desc,
	207	side_tracer_callback_variadic_func call_variadic,
	208	void *priv)
	209	{
	210	if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
	211	return SIDE_ERROR_INVAL;
	212	return _side_tracer_callback_register(desc, (void *) call_variadic, priv);
	213	}
	214
	215	static int _side_tracer_callback_unregister(struct side_event_description *desc,
	216	void call, void priv)
	217	{
0b9e59d6	218	struct side_event_state *event_state;
67337c4a MD	219	struct side_callback old_cb, new_cb;
67337c4a MD	220	const struct side_callback *cb_pos;
b2a84b9f	221	struct side_event_state_0 *es0;
67337c4a MD	222	uint32_t pos_idx;
	223	int ret = SIDE_ERROR_OK;
	224	uint32_t old_nr_cb;
	225
	226	if (!call)
	227	return SIDE_ERROR_INVAL;
	228	if (finalized)
	229	return SIDE_ERROR_EXITING;
	230	if (!initialized)
	231	side_init();
	232	pthread_mutex_lock(&side_lock);
0b9e59d6	233	event_state = side_ptr_get(desc->state);
b2a84b9f MD	234	if (side_unlikely(event_state->version != 0))
	235	abort();
	236	es0 = side_container_of(event_state, struct side_event_state_0, p);
67337c4a MD	237	cb_pos = side_tracer_callback_lookup(desc, call, priv);
	238	if (!cb_pos) {
	239	ret = SIDE_ERROR_NOENT;
	240	goto unlock;
	241	}
3cac1780	242	old_nr_cb = es0->nr_callbacks;
7269a8a3	243	old_cb = (struct side_callback *) es0->callbacks;
67337c4a MD	244	if (old_nr_cb == 1) {
	245	new_cb = (struct side_callback *) &side_empty_callback;
	246	} else {
7269a8a3	247	pos_idx = cb_pos - es0->callbacks;
67337c4a MD	248	/* Remove entry at pos_idx. */
	249	/* old_nr_cb - 1 (removed cb) + 1 (NULL) */
	250	new_cb = (struct side_callback *) calloc(old_nr_cb, sizeof(struct side_callback));
	251	if (!new_cb) {
	252	ret = SIDE_ERROR_NOMEM;
	253	goto unlock;
	254	}
	255	memcpy(new_cb, old_cb, pos_idx);
	256	memcpy(&new_cb[pos_idx], &old_cb[pos_idx + 1], old_nr_cb - pos_idx - 1);
	257	}
f60d8121	258	/* High order bits are already zeroed. */
7269a8a3	259	side_rcu_assign_pointer(es0->callbacks, new_cb);
67337c4a MD	260	side_rcu_wait_grace_period(&rcu_gp);
67337c4a MD	261	free(old_cb);
3cac1780	262	es0->nr_callbacks--;
67337c4a MD	263	/* Decrement concurrently with kernel setting the top bits. */
67337c4a MD	264	if (old_nr_cb == 1)
b2a84b9f	265	(void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
67337c4a MD	266	unlock:
	267	pthread_mutex_unlock(&side_lock);
	268	return ret;
	269	}
	270
	271	int side_tracer_callback_unregister(struct side_event_description *desc,
	272	side_tracer_callback_func call,
	273	void *priv)
	274	{
	275	if (desc->flags & SIDE_EVENT_FLAG_VARIADIC)
	276	return SIDE_ERROR_INVAL;
	277	return _side_tracer_callback_unregister(desc, (void *) call, priv);
	278	}
	279
	280	int side_tracer_callback_variadic_unregister(struct side_event_description *desc,
	281	side_tracer_callback_variadic_func call_variadic,
	282	void *priv)
	283	{
	284	if (!(desc->flags & SIDE_EVENT_FLAG_VARIADIC))
	285	return SIDE_ERROR_INVAL;
	286	return _side_tracer_callback_unregister(desc, (void *) call_variadic, priv);
	287	}
	288
	289	struct side_events_register_handle side_events_register(struct side_event_description *events, uint32_t nr_events)
	290	{
	291	struct side_events_register_handle *events_handle = NULL;
	292	struct side_tracer_handle *tracer_handle;
	293
	294	if (finalized)
	295	return NULL;
	296	if (!initialized)
	297	side_init();
	298	events_handle = (struct side_events_register_handle *)
	299	calloc(1, sizeof(struct side_events_register_handle));
	300	if (!events_handle)
	301	return NULL;
	302	events_handle->events = events;
	303	events_handle->nr_events = nr_events;
	304
	305	pthread_mutex_lock(&side_lock);
	306	side_list_insert_node_tail(&side_events_list, &events_handle->node);
	307	side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
	308	tracer_handle->cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
	309	events, nr_events, tracer_handle->priv);
	310	}
	311	pthread_mutex_unlock(&side_lock);
	312	//TODO: call event batch register ioctl
	313	return events_handle;
	314	}
	315
	316	static
	317	void side_event_remove_callbacks(struct side_event_description *desc)
	318	{
0b9e59d6	319	struct side_event_state *event_state = side_ptr_get(desc->state);
b2a84b9f	320	struct side_event_state_0 *es0;
67337c4a	321	struct side_callback *old_cb;
3cac1780	322	uint32_t nr_cb;
67337c4a	323
b2a84b9f MD	324	if (side_unlikely(event_state->version != 0))
	325	abort();
	326	es0 = side_container_of(event_state, struct side_event_state_0, p);
3cac1780 MD	327	nr_cb = es0->nr_callbacks;
	328	if (!nr_cb)
	329	return;
7269a8a3	330	old_cb = (struct side_callback *) es0->callbacks;
b2a84b9f	331	(void) __atomic_add_fetch(&es0->enabled, -1, __ATOMIC_RELAXED);
67337c4a MD	332	/*
	333	* Setting the state back to 0 cb and empty callbacks out of
	334	* caution. This should not matter because instrumentation is
	335	* unreachable.
	336	*/
3cac1780	337	es0->nr_callbacks = 0;
7269a8a3	338	side_rcu_assign_pointer(es0->callbacks, &side_empty_callback);
67337c4a MD	339	/*
	340	* No need to wait for grace period because instrumentation is
	341	* unreachable.
	342	*/
	343	free(old_cb);
	344	}
	345
	346	/*
	347	* Unregister event handle. At this point, all side events in that
	348	* handle should be unreachable.
	349	*/
	350	void side_events_unregister(struct side_events_register_handle *events_handle)
	351	{
	352	struct side_tracer_handle *tracer_handle;
	353	uint32_t i;
	354
	355	if (!events_handle)
	356	return;
	357	if (finalized)
	358	return;
	359	if (!initialized)
	360	side_init();
	361	pthread_mutex_lock(&side_lock);
	362	side_list_remove_node(&events_handle->node);
	363	side_list_for_each_entry(tracer_handle, &side_tracer_list, node) {
	364	tracer_handle->cb(SIDE_TRACER_NOTIFICATION_REMOVE_EVENTS,
	365	events_handle->events, events_handle->nr_events,
	366	tracer_handle->priv);
	367	}
	368	for (i = 0; i < events_handle->nr_events; i++) {
	369	struct side_event_description *event = events_handle->events[i];
	370
	371	/* Skip NULL pointers */
	372	if (!event)
	373	continue;
	374	side_event_remove_callbacks(event);
	375	}
	376	pthread_mutex_unlock(&side_lock);
	377	//TODO: call event batch unregister ioctl
	378	free(events_handle);
	379	}
	380
	381	struct side_tracer_handle *side_tracer_event_notification_register(
	382	void (*cb)(enum side_tracer_notification notif,
	383	struct side_event_description *events, uint32_t nr_events, void priv),
	384	void *priv)
	385	{
	386	struct side_tracer_handle *tracer_handle;
	387	struct side_events_register_handle *events_handle;
	388
	389	if (finalized)
	390	return NULL;
	391	if (!initialized)
	392	side_init();
	393	tracer_handle = (struct side_tracer_handle *)
	394	calloc(1, sizeof(struct side_tracer_handle));
	395	if (!tracer_handle)
	396	return NULL;
	397	pthread_mutex_lock(&side_lock);
	398	tracer_handle->cb = cb;
	399	tracer_handle->priv = priv;
	400	side_list_insert_node_tail(&side_tracer_list, &tracer_handle->node);
	401	side_list_for_each_entry(events_handle, &side_events_list, node) {
	402	cb(SIDE_TRACER_NOTIFICATION_INSERT_EVENTS,
403	events_handle->events, events_handle->nr_events, priv);
404	}
405	pthread_mutex_unlock(&side_lock);
406	return tracer_handle;
407	}
408
409	void side_tracer_event_notification_unregister(struct side_tracer_handle *tracer_handle)
410	{
411	struct side_events_register_handle *events_handle;
412
413	if (finalized)
414	return;
415	if (!initialized)
416	side_init();
417	pthread_mutex_lock(&side_lock);
418	side_list_for_each_entry(events_handle, &side_events_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	side_list_remove_node(&tracer_handle->node);
424	pthread_mutex_unlock(&side_lock);
be787080	425	free(tracer_handle);
67337c4a MD	426	}
	427
	428	void side_init(void)
	429	{
	430	if (initialized)
	431	return;
	432	side_rcu_gp_init(&rcu_gp);
	433	initialized = true;
	434	}
	435
	436	/*
	437	* side_exit() is executed from a library destructor. It can be called
	438	* explicitly at application exit as well. Concurrent side API use is
	439	* not expected at that point.
	440	*/
	441	void side_exit(void)
	442	{
	443	struct side_events_register_handle handle, tmp;
	444
	445	if (finalized)
	446	return;
	447	side_list_for_each_entry_safe(handle, tmp, &side_events_list, node)
	448	side_events_unregister(handle);
	449	side_rcu_gp_exit(&rcu_gp);
	450	finalized = true;
	451	}