X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=src%2Flttng-syscalls.c;h=e8b72573a42131c95b56e4952a11710e5d2e7957;hb=fad51c94f3e3354e7bcecb58029f25405116eabd;hp=bd836c001d658257e5bf529d61a3cbeabc84a168;hpb=f7d06400be7d046205c20277a03f3f31bf5b1703;p=lttng-modules.git

diff --git a/src/lttng-syscalls.c b/src/lttng-syscalls.c
index bd836c00..e8b72573 100644
--- a/src/lttng-syscalls.c
+++ b/src/lttng-syscalls.c
@@ -28,6 +28,7 @@
 #include <wrapper/file.h>
 #include <wrapper/rcu.h>
 #include <wrapper/syscall.h>
+#include <wrapper/limits.h>
 #include <lttng/events.h>
 #include <lttng/events-internal.h>
 #include <lttng/utils.h>
@@ -65,11 +66,6 @@ enum sc_type {
 void syscall_entry_event_probe(void *__data, struct pt_regs *regs, long id);
 void syscall_exit_event_probe(void *__data, struct pt_regs *regs, long ret);
 
-void syscall_entry_event_notifier_probe(void *__data, struct pt_regs *regs,
-		long id);
-void syscall_exit_event_notifier_probe(void *__data, struct pt_regs *regs,
-		long ret);
-
 /*
  * Forward declarations for old kernels.
  */
@@ -135,6 +131,15 @@ struct lttng_syscall_filter {
 	DECLARE_BITMAP(sc_exit, NR_syscalls);
 	DECLARE_BITMAP(sc_compat_entry, NR_compat_syscalls);
 	DECLARE_BITMAP(sc_compat_exit, NR_compat_syscalls);
+
+	/*
+	 * Reference counters keeping track of number of events enabled
+	 * for each bit.
+	 */
+	u32 sc_entry_refcount_map[NR_syscalls];
+	u32 sc_exit_refcount_map[NR_syscalls];
+	u32 sc_compat_entry_refcount_map[NR_compat_syscalls];
+	u32 sc_compat_exit_refcount_map[NR_compat_syscalls];
 };
 
 static void syscall_entry_event_unknown(struct hlist_head *unknown_action_list_head,
@@ -256,33 +261,33 @@ void syscall_entry_event_call_func(struct hlist_head *action_list,
 
 void syscall_entry_event_probe(void *__data, struct pt_regs *regs, long id)
 {
-	struct lttng_kernel_channel_buffer *chan = __data;
+	struct lttng_kernel_syscall_table *syscall_table = __data;
 	struct hlist_head *action_list, *unknown_action_list;
 	const struct trace_syscall_entry *table, *entry;
 	size_t table_len;
 
 	if (unlikely(in_compat_syscall())) {
-		struct lttng_syscall_filter *filter = chan->priv->parent.sc_filter;
+		struct lttng_syscall_filter *filter = syscall_table->sc_filter;
 
 		if (id < 0 || id >= NR_compat_syscalls
-			|| (!READ_ONCE(chan->priv->parent.syscall_all_entry) && !test_bit(id, filter->sc_compat_entry))) {
+			|| (!READ_ONCE(syscall_table->syscall_all_entry) && !test_bit(id, filter->sc_compat_entry))) {
 			/* System call filtered out. */
 			return;
 		}
 		table = compat_sc_table.table;
 		table_len = compat_sc_table.len;
-		unknown_action_list = &chan->priv->parent.sc_compat_unknown;
+		unknown_action_list = &syscall_table->compat_unknown_syscall_dispatch;
 	} else {
-		struct lttng_syscall_filter *filter = chan->priv->parent.sc_filter;
+		struct lttng_syscall_filter *filter = syscall_table->sc_filter;
 
 		if (id < 0 || id >= NR_syscalls
-			|| (!READ_ONCE(chan->priv->parent.syscall_all_entry) && !test_bit(id, filter->sc_entry))) {
+			|| (!READ_ONCE(syscall_table->syscall_all_entry) && !test_bit(id, filter->sc_entry))) {
 			/* System call filtered out. */
 			return;
 		}
 		table = sc_table.table;
 		table_len = sc_table.len;
-		unknown_action_list = &chan->priv->parent.sc_unknown;
+		unknown_action_list = &syscall_table->unknown_syscall_dispatch;
 	}
 	if (unlikely(id < 0 || id >= table_len)) {
 		syscall_entry_event_unknown(unknown_action_list, regs, id);
@@ -296,9 +301,9 @@ void syscall_entry_event_probe(void *__data, struct pt_regs *regs, long id)
 	}
 
 	if (unlikely(in_compat_syscall())) {
-		action_list = &chan->priv->parent.compat_sc_table[id];
+		action_list = &syscall_table->compat_syscall_dispatch[id];
 	} else {
-		action_list = &chan->priv->parent.sc_table[id];
+		action_list = &syscall_table->syscall_dispatch[id];
 	}
 	if (unlikely(hlist_empty(action_list)))
 		return;
@@ -306,65 +311,6 @@ void syscall_entry_event_probe(void *__data, struct pt_regs *regs, long id)
 	syscall_entry_event_call_func(action_list, entry->event_func, entry->nrargs, regs);
 }
 
-void syscall_entry_event_notifier_probe(void *__data, struct pt_regs *regs,
-		long id)
-{
-	struct lttng_event_notifier_group *group = __data;
-	const struct trace_syscall_entry *table, *entry;
-	struct hlist_head *dispatch_list, *unknown_dispatch_list;
-	size_t table_len;
-
-	if (unlikely(in_compat_syscall())) {
-		struct lttng_syscall_filter *filter = group->sc_filter;
-
-		if (id < 0 || id >= NR_compat_syscalls
-			|| (!READ_ONCE(group->syscall_all_entry) &&
-				!test_bit(id, filter->sc_compat_entry))) {
-			/* System call filtered out. */
-			return;
-		}
-		table = compat_sc_table.table;
-		table_len = compat_sc_table.len;
-		unknown_dispatch_list = &group->event_notifier_compat_unknown_syscall_dispatch;
-	} else {
-		struct lttng_syscall_filter *filter = group->sc_filter;
-
-		if (id < 0 || id >= NR_syscalls
-			|| (!READ_ONCE(group->syscall_all_entry) &&
-				!test_bit(id, filter->sc_entry))) {
-			/* System call filtered out. */
-			return;
-		}
-		table = sc_table.table;
-		table_len = sc_table.len;
-		unknown_dispatch_list = &group->event_notifier_unknown_syscall_dispatch;
-	}
-	/* Check if the syscall id is out of bound. */
-	if (unlikely(id < 0 || id >= table_len)) {
-		syscall_entry_event_unknown(unknown_dispatch_list,
-				regs, id);
-		return;
-	}
-
-	entry = &table[id];
-	if (!entry->event_func) {
-		syscall_entry_event_unknown(unknown_dispatch_list,
-				regs, id);
-		return;
-	}
-
-	if (unlikely(in_compat_syscall())) {
-		dispatch_list = &group->event_notifier_compat_syscall_dispatch[id];
-	} else {
-		dispatch_list = &group->event_notifier_syscall_dispatch[id];
-	}
-	if (unlikely(hlist_empty(dispatch_list)))
-		return;
-
-	syscall_entry_event_call_func(dispatch_list,
-			entry->event_func, entry->nrargs, regs);
-}
-
 static void syscall_exit_event_unknown(struct hlist_head *unknown_action_list_head,
 	struct pt_regs *regs, long id, long ret)
 {
@@ -492,7 +438,7 @@ void syscall_exit_event_call_func(struct hlist_head *action_list,
 
 void syscall_exit_event_probe(void *__data, struct pt_regs *regs, long ret)
 {
-	struct lttng_kernel_channel_buffer *chan = __data;
+	struct lttng_kernel_syscall_table *syscall_table = __data;
 	struct hlist_head *action_list, *unknown_action_list;
 	const struct trace_syscall_entry *table, *entry;
 	size_t table_len;
@@ -501,27 +447,27 @@ void syscall_exit_event_probe(void *__data, struct pt_regs *regs, long ret)
 	id = syscall_get_nr(current, regs);
 
 	if (unlikely(in_compat_syscall())) {
-		struct lttng_syscall_filter *filter = chan->priv->parent.sc_filter;
+		struct lttng_syscall_filter *filter = syscall_table->sc_filter;
 
 		if (id < 0 || id >= NR_compat_syscalls
-			|| (!READ_ONCE(chan->priv->parent.syscall_all_exit) && !test_bit(id, filter->sc_compat_exit))) {
+			|| (!READ_ONCE(syscall_table->syscall_all_exit) && !test_bit(id, filter->sc_compat_exit))) {
 			/* System call filtered out. */
 			return;
 		}
 		table = compat_sc_exit_table.table;
 		table_len = compat_sc_exit_table.len;
-		unknown_action_list = &chan->priv->parent.compat_sc_exit_unknown;
+		unknown_action_list = &syscall_table->compat_unknown_syscall_exit_dispatch;
 	} else {
-		struct lttng_syscall_filter *filter = chan->priv->parent.sc_filter;
+		struct lttng_syscall_filter *filter = syscall_table->sc_filter;
 
 		if (id < 0 || id >= NR_syscalls
-			|| (!READ_ONCE(chan->priv->parent.syscall_all_exit) && !test_bit(id, filter->sc_exit))) {
+			|| (!READ_ONCE(syscall_table->syscall_all_exit) && !test_bit(id, filter->sc_exit))) {
 			/* System call filtered out. */
 			return;
 		}
 		table = sc_exit_table.table;
 		table_len = sc_exit_table.len;
-		unknown_action_list = &chan->priv->parent.sc_exit_unknown;
+		unknown_action_list = &syscall_table->unknown_syscall_exit_dispatch;
 	}
 	if (unlikely(id < 0 || id >= table_len)) {
 		syscall_exit_event_unknown(unknown_action_list, regs, id, ret);
@@ -535,9 +481,9 @@ void syscall_exit_event_probe(void *__data, struct pt_regs *regs, long ret)
 	}
 
 	if (unlikely(in_compat_syscall())) {
-		action_list = &chan->priv->parent.compat_sc_exit_table[id];
+		action_list = &syscall_table->compat_syscall_exit_dispatch[id];
 	} else {
-		action_list = &chan->priv->parent.sc_exit_table[id];
+		action_list = &syscall_table->syscall_exit_dispatch[id];
 	}
 	if (unlikely(hlist_empty(action_list)))
 		return;
@@ -546,109 +492,61 @@ void syscall_exit_event_probe(void *__data, struct pt_regs *regs, long ret)
 			       regs, ret);
 }
 
-void syscall_exit_event_notifier_probe(void *__data, struct pt_regs *regs,
-		long ret)
+static
+struct lttng_kernel_syscall_table *get_syscall_table_from_enabler(struct lttng_event_enabler_common *event_enabler)
 {
-	struct lttng_event_notifier_group *group = __data;
-	const struct trace_syscall_entry *table, *entry;
-	struct hlist_head *dispatch_list, *unknown_dispatch_list;
-	size_t table_len;
-	long id;
-
-	id = syscall_get_nr(current, regs);
-
-	if (unlikely(in_compat_syscall())) {
-		struct lttng_syscall_filter *filter = group->sc_filter;
-
-		if (id < 0 || id >= NR_compat_syscalls
-			|| (!READ_ONCE(group->syscall_all_exit) &&
-				!test_bit(id, filter->sc_compat_exit))) {
-			/* System call filtered out. */
-			return;
-		}
-		table = compat_sc_exit_table.table;
-		table_len = compat_sc_exit_table.len;
-		unknown_dispatch_list = &group->event_notifier_exit_compat_unknown_syscall_dispatch;
-	} else {
-		struct lttng_syscall_filter *filter = group->sc_filter;
-
-		if (id < 0 || id >= NR_syscalls
-			|| (!READ_ONCE(group->syscall_all_exit) &&
-					!test_bit(id, filter->sc_exit))) {
-			/* System call filtered out. */
-			return;
-		}
-		table = sc_exit_table.table;
-		table_len = sc_exit_table.len;
-		unknown_dispatch_list = &group->event_notifier_exit_unknown_syscall_dispatch;
+	switch (event_enabler->enabler_type) {
+	case LTTNG_EVENT_ENABLER_TYPE_RECORDER:
+	{
+		struct lttng_event_recorder_enabler *event_recorder_enabler =
+			container_of(event_enabler, struct lttng_event_recorder_enabler, parent);
+		return &event_recorder_enabler->chan->priv->parent.syscall_table;
 	}
-	/* Check if the syscall id is out of bound. */
-	if (unlikely(id < 0 || id >= table_len)) {
-		syscall_exit_event_unknown(unknown_dispatch_list,
-				regs, id, ret);
-		return;
+	case LTTNG_EVENT_ENABLER_TYPE_NOTIFIER:
+	{
+		struct lttng_event_notifier_enabler *event_notifier_enabler =
+			container_of(event_enabler, struct lttng_event_notifier_enabler, parent);
+		return &event_notifier_enabler->group->syscall_table;
 	}
-
-	entry = &table[id];
-	if (!entry->event_func) {
-		syscall_entry_event_unknown(unknown_dispatch_list,
-				regs, id);
-		return;
+	default:
+		return NULL;
 	}
+}
 
-	if (unlikely(in_compat_syscall())) {
-		dispatch_list = &group->event_notifier_exit_compat_syscall_dispatch[id];
-	} else {
-		dispatch_list = &group->event_notifier_exit_syscall_dispatch[id];
+static
+struct lttng_kernel_syscall_table *get_syscall_table_from_event(struct lttng_kernel_event_common *event)
+{
+	switch (event->type) {
+	case LTTNG_KERNEL_EVENT_TYPE_RECORDER:
+	{
+		struct lttng_kernel_event_recorder *event_recorder =
+			container_of(event, struct lttng_kernel_event_recorder, parent);
+		return &event_recorder->chan->priv->parent.syscall_table;
+	}
+	case LTTNG_KERNEL_EVENT_TYPE_NOTIFIER:
+	{
+		struct lttng_kernel_event_notifier *event_notifier =
+			container_of(event, struct lttng_kernel_event_notifier, parent);
+		return &event_notifier->priv->group->syscall_table;
+	}
+	default:
+		return NULL;
 	}
-	if (unlikely(hlist_empty(dispatch_list)))
-		return;
-
-	syscall_exit_event_call_func(dispatch_list,
-			entry->event_func, entry->nrargs, regs, ret);
 }
-/*
- * noinline to diminish caller stack size.
- * Should be called with sessions lock held.
- */
+
 static
-int lttng_create_syscall_event_if_missing(const struct trace_syscall_entry *table, size_t table_len,
-	struct hlist_head *chan_table, struct lttng_event_enabler *event_enabler,
-	enum sc_type type)
+void lttng_syscall_event_enabler_create_event(struct lttng_event_enabler_common *syscall_event_enabler,
+		const struct lttng_kernel_event_desc *desc, enum sc_type type, unsigned int syscall_nr)
 {
-	struct lttng_kernel_channel_buffer *chan = event_enabler->chan;
-	struct lttng_kernel_session *session = chan->parent.session;
-	unsigned int i;
+	struct lttng_kernel_event_common *event;
 
-	/* Allocate events for each syscall matching enabler, insert into table */
-	for (i = 0; i < table_len; i++) {
-		const struct lttng_kernel_event_desc *desc = table[i].desc;
+	switch (syscall_event_enabler->enabler_type) {
+	case LTTNG_EVENT_ENABLER_TYPE_RECORDER:
+	{
+		struct lttng_event_recorder_enabler *syscall_event_recorder_enabler =
+			container_of(syscall_event_enabler, struct lttng_event_recorder_enabler, parent);
+		struct lttng_event_recorder_enabler *event_recorder_enabler;
 		struct lttng_kernel_abi_event ev;
-		struct lttng_kernel_event_recorder_private *event_recorder_priv;
-		struct lttng_kernel_event_recorder *event_recorder;
-		struct hlist_head *head;
-		bool found = false;
-
-		if (!desc) {
-			/* Unknown syscall */
-			continue;
-		}
-		if (lttng_desc_match_enabler(desc,
-				lttng_event_enabler_as_enabler(event_enabler)) <= 0)
-			continue;
-		/*
-		 * Check if already created.
-		 */
-		head = utils_borrow_hash_table_bucket(
-			session->priv->events_ht.table, LTTNG_EVENT_HT_SIZE,
-			desc->event_name);
-		lttng_hlist_for_each_entry(event_recorder_priv, head, hlist) {
-			if (event_recorder_priv->parent.desc == desc
-				&& event_recorder_priv->pub->chan == event_enabler->chan)
-				found = true;
-		}
-		if (found)
-			continue;
 
 		/* We need to create an event for this syscall/enabler. */
 		memset(&ev, 0, sizeof(ev));
@@ -673,652 +571,313 @@ int lttng_create_syscall_event_if_missing(const struct trace_syscall_entry *tabl
 		strncpy(ev.name, desc->event_name, LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1);
 		ev.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
 		ev.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
-		event_recorder = _lttng_kernel_event_recorder_create(chan, &ev, desc, ev.instrumentation);
-		WARN_ON_ONCE(!event_recorder);
-		if (IS_ERR(event_recorder)) {
-			/*
-			 * If something goes wrong in event registration
-			 * after the first one, we have no choice but to
-			 * leave the previous events in there, until
-			 * deleted by session teardown.
-			 */
-			return PTR_ERR(event_recorder);
-		}
-		hlist_add_head(&event_recorder->priv->parent.u.syscall.node, &chan_table[i]);
-	}
-	return 0;
-}
-
-/*
- * Should be called with sessions lock held.
- */
-int lttng_syscalls_register_event(struct lttng_event_enabler *event_enabler)
-{
-	struct lttng_kernel_channel_buffer *chan = event_enabler->chan;
-	struct lttng_kernel_abi_event ev;
-	int ret;
-
-	wrapper_vmalloc_sync_mappings();
-
-	if (!chan->priv->parent.sc_table) {
-		/* create syscall table mapping syscall to events */
-		chan->priv->parent.sc_table = kzalloc(sizeof(struct lttng_kernel_event_recorder *)
-					* sc_table.len, GFP_KERNEL);
-		if (!chan->priv->parent.sc_table)
-			return -ENOMEM;
-	}
-	if (!chan->priv->parent.sc_exit_table) {
-		/* create syscall table mapping syscall to events */
-		chan->priv->parent.sc_exit_table = kzalloc(sizeof(struct lttng_kernel_event_recorder *)
-					* sc_exit_table.len, GFP_KERNEL);
-		if (!chan->priv->parent.sc_exit_table)
-			return -ENOMEM;
-	}
-
-
-#ifdef CONFIG_COMPAT
-	if (!chan->priv->parent.compat_sc_table) {
-		/* create syscall table mapping compat syscall to events */
-		chan->priv->parent.compat_sc_table = kzalloc(sizeof(struct lttng_kernel_event_recorder *)
-					* compat_sc_table.len, GFP_KERNEL);
-		if (!chan->priv->parent.compat_sc_table)
-			return -ENOMEM;
-	}
-
-	if (!chan->priv->parent.compat_sc_exit_table) {
-		/* create syscall table mapping compat syscall to events */
-		chan->priv->parent.compat_sc_exit_table = kzalloc(sizeof(struct lttng_kernel_event_recorder *)
-					* compat_sc_exit_table.len, GFP_KERNEL);
-		if (!chan->priv->parent.compat_sc_exit_table)
-			return -ENOMEM;
-	}
-#endif
-	if (hlist_empty(&chan->priv->parent.sc_unknown)) {
-		const struct lttng_kernel_event_desc *desc =
-			&__event_desc___syscall_entry_unknown;
-		struct lttng_kernel_event_recorder *event_recorder;
-
-		memset(&ev, 0, sizeof(ev));
-		strncpy(ev.name, desc->event_name, LTTNG_KERNEL_ABI_SYM_NAME_LEN);
-		ev.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
-		ev.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
-		ev.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
-		ev.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
-		event_recorder = _lttng_kernel_event_recorder_create(chan, &ev, desc,
-					    ev.instrumentation);
-		WARN_ON_ONCE(!event_recorder);
-		if (IS_ERR(event_recorder)) {
-			return PTR_ERR(event_recorder);
-		}
-		hlist_add_head(&event_recorder->priv->parent.u.syscall.node, &chan->priv->parent.sc_unknown);
-	}
-
-	if (hlist_empty(&chan->priv->parent.sc_compat_unknown)) {
-		const struct lttng_kernel_event_desc *desc =
-			&__event_desc___compat_syscall_entry_unknown;
-		struct lttng_kernel_event_recorder *event_recorder;
-
-		memset(&ev, 0, sizeof(ev));
-		strncpy(ev.name, desc->event_name, LTTNG_KERNEL_ABI_SYM_NAME_LEN);
-		ev.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
-		ev.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
-		ev.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
-		ev.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
-		event_recorder = _lttng_kernel_event_recorder_create(chan, &ev, desc,
-					    ev.instrumentation);
-		WARN_ON_ONCE(!event_recorder);
-		if (IS_ERR(event_recorder)) {
-			return PTR_ERR(event_recorder);
+		event_recorder_enabler = lttng_event_recorder_enabler_create(LTTNG_ENABLER_FORMAT_NAME, &ev,
+				syscall_event_recorder_enabler->chan);
+		WARN_ON_ONCE(!event_recorder_enabler);
+		if (!event_recorder_enabler)
+			return;
+		event = _lttng_kernel_event_create(&event_recorder_enabler->parent, desc);
+		WARN_ON_ONCE(IS_ERR(event));
+		lttng_event_enabler_destroy(&event_recorder_enabler->parent);
+		if (IS_ERR(event)) {
+			printk(KERN_INFO "Unable to create event recorder %s\n", desc->event_name);
+			return;
 		}
-		hlist_add_head(&event_recorder->priv->parent.u.syscall.node, &chan->priv->parent.sc_compat_unknown);
+		event->priv->u.syscall.syscall_id = syscall_nr;
+		break;
 	}
+	case LTTNG_EVENT_ENABLER_TYPE_NOTIFIER:
+	{
+		struct lttng_event_notifier_enabler *syscall_event_notifier_enabler =
+			container_of(syscall_event_enabler, struct lttng_event_notifier_enabler, parent);
+		struct lttng_event_notifier_enabler *event_notifier_enabler;
+		struct lttng_kernel_abi_event_notifier event_notifier_param;
+		uint64_t user_token = syscall_event_enabler->user_token;
+		uint64_t error_counter_index = syscall_event_notifier_enabler->error_counter_index;
 
-	if (hlist_empty(&chan->priv->parent.compat_sc_exit_unknown)) {
-		const struct lttng_kernel_event_desc *desc =
-			&__event_desc___compat_syscall_exit_unknown;
-		struct lttng_kernel_event_recorder *event_recorder;
-
-		memset(&ev, 0, sizeof(ev));
-		strncpy(ev.name, desc->event_name, LTTNG_KERNEL_ABI_SYM_NAME_LEN);
-		ev.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
-		ev.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
-		ev.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
-		ev.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
-		event_recorder = _lttng_kernel_event_recorder_create(chan, &ev, desc,
-					    ev.instrumentation);
-		WARN_ON_ONCE(!event_recorder);
-		if (IS_ERR(event_recorder)) {
-			return PTR_ERR(event_recorder);
+		memset(&event_notifier_param, 0, sizeof(event_notifier_param));
+		switch (type) {
+		case SC_TYPE_ENTRY:
+			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
+			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
+			break;
+		case SC_TYPE_EXIT:
+			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
+			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
+			break;
+		case SC_TYPE_COMPAT_ENTRY:
+			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
+			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
+			break;
+		case SC_TYPE_COMPAT_EXIT:
+			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
+			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
+			break;
 		}
-		hlist_add_head(&event_recorder->priv->parent.u.syscall.node, &chan->priv->parent.compat_sc_exit_unknown);
-	}
-
-	if (hlist_empty(&chan->priv->parent.sc_exit_unknown)) {
-		const struct lttng_kernel_event_desc *desc =
-			&__event_desc___syscall_exit_unknown;
-		struct lttng_kernel_event_recorder *event_recorder;
-
-		memset(&ev, 0, sizeof(ev));
-		strncpy(ev.name, desc->event_name, LTTNG_KERNEL_ABI_SYM_NAME_LEN);
-		ev.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
-		ev.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
-		ev.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
-		ev.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
-		event_recorder = _lttng_kernel_event_recorder_create(chan, &ev, desc,
-					    ev.instrumentation);
-		WARN_ON_ONCE(!event_recorder);
-		if (IS_ERR(event_recorder)) {
-			return PTR_ERR(event_recorder);
+		strncat(event_notifier_param.event.name, desc->event_name,
+			LTTNG_KERNEL_ABI_SYM_NAME_LEN - strlen(event_notifier_param.event.name) - 1);
+		event_notifier_param.event.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
+		event_notifier_param.event.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
+		event_notifier_param.event.token = user_token;
+		event_notifier_param.error_counter_index = error_counter_index;
+
+		event_notifier_enabler = lttng_event_notifier_enabler_create(LTTNG_ENABLER_FORMAT_NAME,
+				&event_notifier_param, syscall_event_notifier_enabler->group);
+		WARN_ON_ONCE(!event_notifier_enabler);
+		event = _lttng_kernel_event_create(&event_notifier_enabler->parent, desc);
+		WARN_ON_ONCE(IS_ERR(event));
+		lttng_event_enabler_destroy(&event_notifier_enabler->parent);
+		if (IS_ERR(event)) {
+			printk(KERN_INFO "Unable to create event notifier %s\n", desc->event_name);
+			return;
 		}
-		hlist_add_head(&event_recorder->priv->parent.u.syscall.node, &chan->priv->parent.sc_exit_unknown);
-	}
-
-	ret = lttng_create_syscall_event_if_missing(sc_table.table, sc_table.len,
-			chan->priv->parent.sc_table, event_enabler, SC_TYPE_ENTRY);
-	if (ret)
-		return ret;
-	ret = lttng_create_syscall_event_if_missing(sc_exit_table.table, sc_exit_table.len,
-			chan->priv->parent.sc_exit_table, event_enabler, SC_TYPE_EXIT);
-	if (ret)
-		return ret;
-
-#ifdef CONFIG_COMPAT
-	ret = lttng_create_syscall_event_if_missing(compat_sc_table.table, compat_sc_table.len,
-			chan->priv->parent.compat_sc_table, event_enabler, SC_TYPE_COMPAT_ENTRY);
-	if (ret)
-		return ret;
-	ret = lttng_create_syscall_event_if_missing(compat_sc_exit_table.table, compat_sc_exit_table.len,
-			chan->priv->parent.compat_sc_exit_table, event_enabler, SC_TYPE_COMPAT_EXIT);
-	if (ret)
-		return ret;
-#endif
-
-	if (!chan->priv->parent.sc_filter) {
-		chan->priv->parent.sc_filter = kzalloc(sizeof(struct lttng_syscall_filter),
-				GFP_KERNEL);
-		if (!chan->priv->parent.sc_filter)
-			return -ENOMEM;
-	}
-
-	if (!chan->priv->parent.sys_enter_registered) {
-		ret = lttng_wrapper_tracepoint_probe_register("sys_enter",
-				(void *) syscall_entry_event_probe, chan);
-		if (ret)
-			return ret;
-		chan->priv->parent.sys_enter_registered = 1;
+		event->priv->u.syscall.syscall_id = syscall_nr;
+		break;
 	}
-	/*
-	 * We change the name of sys_exit tracepoint due to namespace
-	 * conflict with sys_exit syscall entry.
-	 */
-	if (!chan->priv->parent.sys_exit_registered) {
-		ret = lttng_wrapper_tracepoint_probe_register("sys_exit",
-				(void *) syscall_exit_event_probe, chan);
-		if (ret) {
-			WARN_ON_ONCE(lttng_wrapper_tracepoint_probe_unregister("sys_enter",
-				(void *) syscall_entry_event_probe, chan));
-			return ret;
-		}
-		chan->priv->parent.sys_exit_registered = 1;
+	default:
+		break;
 	}
-	return ret;
 }
 
-/*
- * Should be called with sessions lock held.
- */
-int lttng_syscalls_register_event_notifier(
-		struct lttng_event_notifier_enabler *event_notifier_enabler)
+static
+void lttng_syscall_event_enabler_create_matching_syscall_table_events(struct lttng_event_enabler_common *syscall_event_enabler_common,
+		const struct trace_syscall_entry *table, size_t table_len, enum sc_type type)
 {
-	struct lttng_event_notifier_group *group = event_notifier_enabler->group;
+	struct lttng_event_ht *events_ht = lttng_get_event_ht_from_enabler(syscall_event_enabler_common);
+	const struct lttng_kernel_event_desc *desc;
 	unsigned int i;
-	int ret = 0;
-
-	wrapper_vmalloc_sync_mappings();
-
-	if (!group->event_notifier_syscall_dispatch) {
-		group->event_notifier_syscall_dispatch =
-				kzalloc(sizeof(struct hlist_head) * sc_table.len,
-					GFP_KERNEL);
-		if (!group->event_notifier_syscall_dispatch)
-			return -ENOMEM;
-
-		/* Initialize all list_head */
-		for (i = 0; i < sc_table.len; i++)
-			INIT_HLIST_HEAD(&group->event_notifier_syscall_dispatch[i]);
-
-		/* Init the unknown syscall notifier list. */
-		INIT_HLIST_HEAD(&group->event_notifier_unknown_syscall_dispatch);
-	}
-
-	if (!group->event_notifier_exit_syscall_dispatch) {
-		group->event_notifier_exit_syscall_dispatch =
-				kzalloc(sizeof(struct hlist_head) * sc_table.len,
-					GFP_KERNEL);
-		if (!group->event_notifier_exit_syscall_dispatch)
-			return -ENOMEM;
-
-		/* Initialize all list_head */
-		for (i = 0; i < sc_table.len; i++)
-			INIT_HLIST_HEAD(&group->event_notifier_exit_syscall_dispatch[i]);
-
-		/* Init the unknown exit syscall notifier list. */
-		INIT_HLIST_HEAD(&group->event_notifier_exit_unknown_syscall_dispatch);
-	}
-
-#ifdef CONFIG_COMPAT
-	if (!group->event_notifier_compat_syscall_dispatch) {
-		group->event_notifier_compat_syscall_dispatch =
-				kzalloc(sizeof(struct hlist_head) * compat_sc_table.len,
-					GFP_KERNEL);
-		if (!group->event_notifier_syscall_dispatch)
-			return -ENOMEM;
-
-		/* Initialize all list_head */
-		for (i = 0; i < compat_sc_table.len; i++)
-			INIT_HLIST_HEAD(&group->event_notifier_compat_syscall_dispatch[i]);
-
-		/* Init the unknown syscall notifier list. */
-		INIT_HLIST_HEAD(&group->event_notifier_compat_unknown_syscall_dispatch);
-	}
-
-	if (!group->event_notifier_exit_compat_syscall_dispatch) {
-		group->event_notifier_exit_compat_syscall_dispatch =
-				kzalloc(sizeof(struct hlist_head) * compat_sc_exit_table.len,
-					GFP_KERNEL);
-		if (!group->event_notifier_exit_syscall_dispatch)
-			return -ENOMEM;
 
-		/* Initialize all list_head */
-		for (i = 0; i < compat_sc_exit_table.len; i++)
-			INIT_HLIST_HEAD(&group->event_notifier_exit_compat_syscall_dispatch[i]);
-
-		/* Init the unknown exit syscall notifier list. */
-		INIT_HLIST_HEAD(&group->event_notifier_exit_compat_unknown_syscall_dispatch);
-	}
+#ifndef CONFIG_COMPAT
+	if (type == SC_TYPE_COMPAT_ENTRY || type == SC_TYPE_COMPAT_EXIT)
+		return;
 #endif
+	/* iterate over all syscall and create event that match */
+	for (i = 0; i < table_len; i++) {
+		struct lttng_kernel_event_common_private *event_priv;
+		struct hlist_head *head;
+		bool found = false;
 
-	if (!group->sc_filter) {
-		group->sc_filter = kzalloc(sizeof(struct lttng_syscall_filter),
-				GFP_KERNEL);
-		if (!group->sc_filter)
-			return -ENOMEM;
-	}
+		desc = table[i].desc;
+		if (!desc) {
+			/* Unknown syscall */
+			continue;
+		}
 
-	if (!group->sys_enter_registered) {
-		ret = lttng_wrapper_tracepoint_probe_register("sys_enter",
-				(void *) syscall_entry_event_notifier_probe, group);
-		if (ret)
-			return ret;
-		group->sys_enter_registered = 1;
-	}
+		if (!lttng_desc_match_enabler(desc, syscall_event_enabler_common))
+			continue;
 
-	if (!group->sys_exit_registered) {
-		ret = lttng_wrapper_tracepoint_probe_register("sys_exit",
-				(void *) syscall_exit_event_notifier_probe, group);
-		if (ret) {
-			WARN_ON_ONCE(lttng_wrapper_tracepoint_probe_unregister("sys_enter",
-				(void *) syscall_entry_event_notifier_probe, group));
-			return ret;
+		/*
+		 * Check if already created.
+		 */
+		head = utils_borrow_hash_table_bucket(events_ht->table, LTTNG_EVENT_HT_SIZE, desc->event_name);
+		lttng_hlist_for_each_entry(event_priv, head, hlist_node) {
+			if (lttng_event_enabler_desc_match_event(syscall_event_enabler_common, desc, event_priv->pub)) {
+				found = true;
+				break;
+			}
 		}
-		group->sys_exit_registered = 1;
+		if (found)
+			continue;
+
+		lttng_syscall_event_enabler_create_event(syscall_event_enabler_common, desc, type, i);
 	}
+}
 
-	return ret;
+static
+bool lttng_syscall_event_enabler_is_wildcard_all(struct lttng_event_enabler_common *event_enabler)
+{
+	if (event_enabler->event_param.instrumentation != LTTNG_KERNEL_ABI_SYSCALL)
+		return false;
+	if (event_enabler->event_param.u.syscall.abi != LTTNG_KERNEL_ABI_SYSCALL_ABI_ALL)
+		return false;
+	if (event_enabler->event_param.u.syscall.match != LTTNG_KERNEL_ABI_SYSCALL_MATCH_NAME)
+		return false;
+	if (strcmp(event_enabler->event_param.name, "*"))
+		return false;
+	return true;
 }
 
 static
-int create_unknown_event_notifier(
-		struct lttng_event_notifier_enabler *event_notifier_enabler,
-		enum sc_type type)
+void create_unknown_syscall_event(struct lttng_event_enabler_common *event_enabler, enum sc_type type)
 {
-	struct lttng_kernel_event_notifier_private *event_notifier_priv;
-	struct lttng_kernel_event_notifier *event_notifier;
+	struct lttng_event_ht *events_ht = lttng_get_event_ht_from_enabler(event_enabler);
+	struct lttng_kernel_event_common_private *event_priv;
 	const struct lttng_kernel_event_desc *desc;
-	struct lttng_event_notifier_group *group = event_notifier_enabler->group;
-	struct lttng_kernel_abi_event_notifier event_notifier_param;
-	uint64_t user_token = event_notifier_enabler->base.user_token;
-	uint64_t error_counter_index = event_notifier_enabler->error_counter_index;
-	struct lttng_enabler *base_enabler = lttng_event_notifier_enabler_as_enabler(
-		event_notifier_enabler);
-	struct hlist_head *unknown_dispatch_list;
-	int ret = 0;
 	bool found = false;
-	enum lttng_kernel_abi_syscall_abi abi;
-	enum lttng_kernel_abi_syscall_entryexit entryexit;
 	struct hlist_head *head;
 
+#ifndef CONFIG_COMPAT
+	if (type == SC_TYPE_COMPAT_ENTRY || type == SC_TYPE_COMPAT_EXIT)
+		return;
+#endif
+	/*
+	 * Considering that currently system calls can only be enabled on a per
+	 * name basis (or wildcard based on a name), unknown syscall events are
+	 * only used when matching *all* system calls, because this is the only
+	 * case which can be associated with an unknown system call.
+	 *
+	 * When enabling system call on a per system call number basis will be
+	 * supported, this will need to be revisited.
+	 */
+	if (!lttng_syscall_event_enabler_is_wildcard_all(event_enabler))
+		return;
+
 	switch (type) {
 	case SC_TYPE_ENTRY:
 		desc = &__event_desc___syscall_entry_unknown;
-		unknown_dispatch_list = &group->event_notifier_unknown_syscall_dispatch;
-		entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
-		abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
 		break;
 	case SC_TYPE_EXIT:
 		desc = &__event_desc___syscall_exit_unknown;
-		unknown_dispatch_list = &group->event_notifier_exit_unknown_syscall_dispatch;
-		entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
-		abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
 		break;
 	case SC_TYPE_COMPAT_ENTRY:
 		desc = &__event_desc___compat_syscall_entry_unknown;
-		unknown_dispatch_list = &group->event_notifier_compat_unknown_syscall_dispatch;
-		entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
-		abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
 		break;
 	case SC_TYPE_COMPAT_EXIT:
 		desc = &__event_desc___compat_syscall_exit_unknown;
-		unknown_dispatch_list = &group->event_notifier_exit_compat_unknown_syscall_dispatch;
-		entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
-		abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
 		break;
 	default:
-		BUG_ON(1);
+		WARN_ON_ONCE(1);
 	}
 
 	/*
 	 * Check if already created.
 	 */
-	head = utils_borrow_hash_table_bucket(group->event_notifiers_ht.table,
-		LTTNG_EVENT_NOTIFIER_HT_SIZE, desc->event_name);
-	lttng_hlist_for_each_entry(event_notifier_priv, head, hlist) {
-		if (event_notifier_priv->parent.desc == desc &&
-				event_notifier_priv->parent.user_token == base_enabler->user_token)
+	head = utils_borrow_hash_table_bucket(events_ht->table, LTTNG_EVENT_HT_SIZE, desc->event_name);
+	lttng_hlist_for_each_entry(event_priv, head, hlist_node) {
+		if (lttng_event_enabler_desc_match_event(event_enabler, desc, event_priv->pub)) {
 			found = true;
-	}
-	if (found)
-		goto end;
-
-	memset(&event_notifier_param, 0, sizeof(event_notifier_param));
-	strncat(event_notifier_param.event.name, desc->event_name,
-		LTTNG_KERNEL_ABI_SYM_NAME_LEN - strlen(event_notifier_param.event.name) - 1);
-
-	event_notifier_param.event.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
-
-	event_notifier_param.event.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
-	event_notifier_param.event.u.syscall.abi = abi;
-	event_notifier_param.event.u.syscall.entryexit = entryexit;
-
-	event_notifier = _lttng_event_notifier_create(desc, user_token,
-		error_counter_index, group, &event_notifier_param,
-		event_notifier_param.event.instrumentation);
-	if (IS_ERR(event_notifier)) {
-		printk(KERN_INFO "Unable to create unknown notifier %s\n",
-			desc->event_name);
-		ret = -ENOMEM;
-		goto end;
-	}
-
-	hlist_add_head_rcu(&event_notifier->priv->parent.u.syscall.node, unknown_dispatch_list);
-
-end:
-	return ret;
-}
-
-static int create_matching_event_notifiers(
-		struct lttng_event_notifier_enabler *event_notifier_enabler,
-		const struct trace_syscall_entry *table,
-		size_t table_len, enum sc_type type)
-{
-	struct lttng_event_notifier_group *group = event_notifier_enabler->group;
-	const struct lttng_kernel_event_desc *desc;
-	uint64_t user_token = event_notifier_enabler->base.user_token;
-	uint64_t error_counter_index = event_notifier_enabler->error_counter_index;
-	unsigned int i;
-	int ret = 0;
-
-	/* iterate over all syscall and create event_notifier that match */
-	for (i = 0; i < table_len; i++) {
-		struct lttng_kernel_event_notifier_private *event_notifier_priv;
-		struct lttng_kernel_event_notifier *event_notifier;
-		struct lttng_kernel_abi_event_notifier event_notifier_param;
-		struct hlist_head *head;
-		int found = 0;
-
-		desc = table[i].desc;
-		if (!desc) {
-			/* Unknown syscall */
-			continue;
-		}
-
-		if (!lttng_desc_match_enabler(desc,
-				lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
-			continue;
-
-		/*
-		 * Check if already created.
-		 */
-		head = utils_borrow_hash_table_bucket(group->event_notifiers_ht.table,
-			LTTNG_EVENT_NOTIFIER_HT_SIZE, desc->event_name);
-		lttng_hlist_for_each_entry(event_notifier_priv, head, hlist) {
-			if (event_notifier_priv->parent.desc == desc
-				&& event_notifier_priv->parent.user_token == event_notifier_enabler->base.user_token)
-				found = 1;
-		}
-		if (found)
-			continue;
-
-		memset(&event_notifier_param, 0, sizeof(event_notifier_param));
-		switch (type) {
-		case SC_TYPE_ENTRY:
-			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
-			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
-			break;
-		case SC_TYPE_EXIT:
-			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
-			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_NATIVE;
-			break;
-		case SC_TYPE_COMPAT_ENTRY:
-			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_ENTRY;
-			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
-			break;
-		case SC_TYPE_COMPAT_EXIT:
-			event_notifier_param.event.u.syscall.entryexit = LTTNG_KERNEL_ABI_SYSCALL_EXIT;
-			event_notifier_param.event.u.syscall.abi = LTTNG_KERNEL_ABI_SYSCALL_ABI_COMPAT;
 			break;
 		}
-		strncat(event_notifier_param.event.name, desc->event_name,
-			LTTNG_KERNEL_ABI_SYM_NAME_LEN - strlen(event_notifier_param.event.name) - 1);
-		event_notifier_param.event.name[LTTNG_KERNEL_ABI_SYM_NAME_LEN - 1] = '\0';
-		event_notifier_param.event.instrumentation = LTTNG_KERNEL_ABI_SYSCALL;
-
-		event_notifier = _lttng_event_notifier_create(desc, user_token,
-			error_counter_index, group, &event_notifier_param,
-			event_notifier_param.event.instrumentation);
-		if (IS_ERR(event_notifier)) {
-			printk(KERN_INFO "Unable to create event_notifier %s\n",
-				desc->event_name);
-			ret = -ENOMEM;
-			goto end;
-		}
-
-		event_notifier->priv->parent.u.syscall.syscall_id = i;
 	}
-
-end:
-	return ret;
-
+	if (!found)
+		lttng_syscall_event_enabler_create_event(event_enabler, desc, type, -1U);
 }
 
-int lttng_syscalls_create_matching_event_notifiers(
-		struct lttng_event_notifier_enabler *event_notifier_enabler)
+static
+void lttng_syscall_event_enabler_create_matching_events(struct lttng_event_enabler_common *event_enabler)
 {
-	int ret;
-	struct lttng_enabler *base_enabler =
-			lttng_event_notifier_enabler_as_enabler(event_notifier_enabler);
-	enum lttng_kernel_abi_syscall_entryexit entryexit =
-			base_enabler->event_param.u.syscall.entryexit;
+	enum lttng_kernel_abi_syscall_entryexit entryexit = event_enabler->event_param.u.syscall.entryexit;
 
 	if (entryexit == LTTNG_KERNEL_ABI_SYSCALL_ENTRY || entryexit == LTTNG_KERNEL_ABI_SYSCALL_ENTRYEXIT) {
-		ret = create_matching_event_notifiers(event_notifier_enabler,
+		lttng_syscall_event_enabler_create_matching_syscall_table_events(event_enabler,
 			sc_table.table, sc_table.len, SC_TYPE_ENTRY);
-		if (ret)
-			goto end;
-
-		ret = create_matching_event_notifiers(event_notifier_enabler,
-			compat_sc_table.table, compat_sc_table.len,
-			SC_TYPE_COMPAT_ENTRY);
-		if (ret)
-			goto end;
-
-		ret = create_unknown_event_notifier(event_notifier_enabler,
-				SC_TYPE_ENTRY);
-		if (ret)
-			goto end;
-
-		ret = create_unknown_event_notifier(event_notifier_enabler,
-				SC_TYPE_COMPAT_ENTRY);
-		if (ret)
-			goto end;
+		lttng_syscall_event_enabler_create_matching_syscall_table_events(event_enabler,
+			compat_sc_table.table, compat_sc_table.len, SC_TYPE_COMPAT_ENTRY);
+		create_unknown_syscall_event(event_enabler, SC_TYPE_ENTRY);
+		create_unknown_syscall_event(event_enabler, SC_TYPE_COMPAT_ENTRY);
 	}
 
 	if (entryexit == LTTNG_KERNEL_ABI_SYSCALL_EXIT || entryexit == LTTNG_KERNEL_ABI_SYSCALL_ENTRYEXIT) {
-		ret = create_matching_event_notifiers(event_notifier_enabler,
-			sc_exit_table.table, sc_exit_table.len,
-			SC_TYPE_EXIT);
-		if (ret)
-			goto end;
-
-		ret = create_unknown_event_notifier(event_notifier_enabler,
-				SC_TYPE_EXIT);
-		if (ret)
-			goto end;
-
-		ret = create_matching_event_notifiers(event_notifier_enabler,
-			compat_sc_exit_table.table, compat_sc_exit_table.len,
-			SC_TYPE_COMPAT_EXIT);
-		if (ret)
-			goto end;
-
-		ret = create_unknown_event_notifier(event_notifier_enabler,
-				SC_TYPE_COMPAT_EXIT);
-		if (ret)
-			goto end;
+		lttng_syscall_event_enabler_create_matching_syscall_table_events(event_enabler,
+			sc_exit_table.table, sc_exit_table.len, SC_TYPE_EXIT);
+		lttng_syscall_event_enabler_create_matching_syscall_table_events(event_enabler,
+			compat_sc_exit_table.table, compat_sc_exit_table.len, SC_TYPE_COMPAT_EXIT);
+		create_unknown_syscall_event(event_enabler, SC_TYPE_EXIT);
+		create_unknown_syscall_event(event_enabler, SC_TYPE_COMPAT_EXIT);
 	}
-
-end:
-	return ret;
 }
 
 /*
- * Unregister the syscall event_notifier probes from the callsites.
+ * Should be called with sessions lock held.
  */
-int lttng_syscalls_unregister_event_notifier_group(
-		struct lttng_event_notifier_group *event_notifier_group)
+int lttng_event_enabler_create_syscall_events_if_missing(struct lttng_event_enabler_common *syscall_event_enabler)
 {
+	struct lttng_kernel_syscall_table *syscall_table = get_syscall_table_from_enabler(syscall_event_enabler);
 	int ret;
 
-	/*
-	 * Only register the event_notifier probe on the `sys_enter` callsite for now.
-	 * At the moment, we don't think it's desirable to have one fired
-	 * event_notifier for the entry and one for the exit of a syscall.
-	 */
-	if (event_notifier_group->sys_enter_registered) {
-		ret = lttng_wrapper_tracepoint_probe_unregister("sys_enter",
-				(void *) syscall_entry_event_notifier_probe, event_notifier_group);
+	if (!syscall_table->syscall_dispatch) {
+		/* create syscall table mapping syscall to events */
+		syscall_table->syscall_dispatch = kzalloc(sizeof(struct hlist_head) * sc_table.len, GFP_KERNEL);
+		if (!syscall_table->syscall_dispatch)
+			return -ENOMEM;
+	}
+	if (!syscall_table->syscall_exit_dispatch) {
+		/* create syscall table mapping syscall to events */
+		syscall_table->syscall_exit_dispatch = kzalloc(sizeof(struct hlist_head) * sc_exit_table.len, GFP_KERNEL);
+		if (!syscall_table->syscall_exit_dispatch)
+			return -ENOMEM;
+	}
+
+#ifdef CONFIG_COMPAT
+	if (!syscall_table->compat_syscall_dispatch) {
+		/* create syscall table mapping compat syscall to events */
+		syscall_table->compat_syscall_dispatch = kzalloc(sizeof(struct hlist_head) * compat_sc_table.len, GFP_KERNEL);
+		if (!syscall_table->compat_syscall_dispatch)
+			return -ENOMEM;
+	}
+
+	if (!syscall_table->compat_syscall_exit_dispatch) {
+		/* create syscall table mapping compat syscall to events */
+		syscall_table->compat_syscall_exit_dispatch = kzalloc(sizeof(struct hlist_head) * compat_sc_exit_table.len, GFP_KERNEL);
+		if (!syscall_table->compat_syscall_exit_dispatch)
+			return -ENOMEM;
+	}
+#endif
+	if (!syscall_table->sc_filter) {
+		syscall_table->sc_filter = kzalloc(sizeof(struct lttng_syscall_filter),
+				GFP_KERNEL);
+		if (!syscall_table->sc_filter)
+			return -ENOMEM;
+	}
+
+	if (!syscall_table->sys_enter_registered) {
+		ret = lttng_wrapper_tracepoint_probe_register("sys_enter",
+				(void *) syscall_entry_event_probe, syscall_table);
 		if (ret)
 			return ret;
-		event_notifier_group->sys_enter_registered = 0;
+		syscall_table->sys_enter_registered = 1;
 	}
-	if (event_notifier_group->sys_exit_registered) {
-		ret = lttng_wrapper_tracepoint_probe_unregister("sys_exit",
-				(void *) syscall_exit_event_notifier_probe, event_notifier_group);
-		if (ret)
+	if (!syscall_table->sys_exit_registered) {
+		ret = lttng_wrapper_tracepoint_probe_register("sys_exit",
+				(void *) syscall_exit_event_probe, syscall_table);
+		if (ret) {
+			WARN_ON_ONCE(lttng_wrapper_tracepoint_probe_unregister("sys_enter",
+				(void *) syscall_entry_event_probe, syscall_table));
 			return ret;
-		event_notifier_group->sys_enter_registered = 0;
+		}
+		syscall_table->sys_exit_registered = 1;
 	}
 
-	kfree(event_notifier_group->event_notifier_syscall_dispatch);
-	kfree(event_notifier_group->event_notifier_exit_syscall_dispatch);
-#ifdef CONFIG_COMPAT
-	kfree(event_notifier_group->event_notifier_compat_syscall_dispatch);
-	kfree(event_notifier_group->event_notifier_exit_compat_syscall_dispatch);
-#endif
+	lttng_syscall_event_enabler_create_matching_events(syscall_event_enabler);
+
 	return 0;
 }
 
-int lttng_syscalls_unregister_channel(struct lttng_kernel_channel_buffer *chan)
+int lttng_syscalls_unregister_syscall_table(struct lttng_kernel_syscall_table *syscall_table)
 {
 	int ret;
 
-	if (!chan->priv->parent.sc_table)
+	if (!syscall_table->syscall_dispatch)
 		return 0;
-	if (chan->priv->parent.sys_enter_registered) {
+	if (syscall_table->sys_enter_registered) {
 		ret = lttng_wrapper_tracepoint_probe_unregister("sys_enter",
-				(void *) syscall_entry_event_probe, chan);
+				(void *) syscall_entry_event_probe, syscall_table);
 		if (ret)
 			return ret;
-		chan->priv->parent.sys_enter_registered = 0;
+		syscall_table->sys_enter_registered = 0;
 	}
-	if (chan->priv->parent.sys_exit_registered) {
+	if (syscall_table->sys_exit_registered) {
 		ret = lttng_wrapper_tracepoint_probe_unregister("sys_exit",
-				(void *) syscall_exit_event_probe, chan);
+				(void *) syscall_exit_event_probe, syscall_table);
 		if (ret)
 			return ret;
-		chan->priv->parent.sys_exit_registered = 0;
+		syscall_table->sys_exit_registered = 0;
 	}
 	return 0;
 }
 
-int lttng_syscalls_destroy_event(struct lttng_kernel_channel_buffer *chan)
+int lttng_syscalls_destroy_syscall_table(struct lttng_kernel_syscall_table *syscall_table)
 {
-	kfree(chan->priv->parent.sc_table);
-	kfree(chan->priv->parent.sc_exit_table);
+	kfree(syscall_table->syscall_dispatch);
+	kfree(syscall_table->syscall_exit_dispatch);
 #ifdef CONFIG_COMPAT
-	kfree(chan->priv->parent.compat_sc_table);
-	kfree(chan->priv->parent.compat_sc_exit_table);
+	kfree(syscall_table->compat_syscall_dispatch);
+	kfree(syscall_table->compat_syscall_exit_dispatch);
 #endif
-	kfree(chan->priv->parent.sc_filter);
+	kfree(syscall_table->sc_filter);
 	return 0;
 }
 
-static
-int get_syscall_nr(const char *syscall_name)
-{
-	int syscall_nr = -1;
-	int i;
-
-	for (i = 0; i < sc_table.len; i++) {
-		const struct trace_syscall_entry *entry;
-		const char *it_name;
-
-		entry = &sc_table.table[i];
-		if (!entry->desc)
-			continue;
-		it_name = entry->desc->event_name;
-		it_name += strlen(SYSCALL_ENTRY_STR);
-		if (!strcmp(syscall_name, it_name)) {
-			syscall_nr = i;
-			break;
-		}
-	}
-	return syscall_nr;
-}
-
-static
-int get_compat_syscall_nr(const char *syscall_name)
-{
-	int syscall_nr = -1;
-	int i;
-
-	for (i = 0; i < compat_sc_table.len; i++) {
-		const struct trace_syscall_entry *entry;
-		const char *it_name;
-
-		entry = &compat_sc_table.table[i];
-		if (!entry->desc)
-			continue;
-		it_name = entry->desc->event_name;
-		it_name += strlen(COMPAT_SYSCALL_ENTRY_STR);
-		if (!strcmp(syscall_name, it_name)) {
-			syscall_nr = i;
-			break;
-		}
-	}
-	return syscall_nr;
-}
-
 static
 uint32_t get_sc_tables_len(void)
 {
@@ -1363,35 +922,25 @@ static
 int lttng_syscall_filter_enable(
 		struct lttng_syscall_filter *filter,
 		const char *desc_name, enum lttng_syscall_abi abi,
-		enum lttng_syscall_entryexit entryexit)
+		enum lttng_syscall_entryexit entryexit,
+		unsigned int syscall_id)
 {
 	const char *syscall_name;
 	unsigned long *bitmap;
-	int syscall_nr;
+	u32 *refcount_map;
 
 	syscall_name = get_syscall_name(desc_name, abi, entryexit);
 
-	switch (abi) {
-	case LTTNG_SYSCALL_ABI_NATIVE:
-		syscall_nr = get_syscall_nr(syscall_name);
-		break;
-	case LTTNG_SYSCALL_ABI_COMPAT:
-		syscall_nr = get_compat_syscall_nr(syscall_name);
-		break;
-	default:
-		return -EINVAL;
-	}
-	if (syscall_nr < 0)
-		return -ENOENT;
-
 	switch (entryexit) {
 	case LTTNG_SYSCALL_ENTRY:
 		switch (abi) {
 		case LTTNG_SYSCALL_ABI_NATIVE:
 			bitmap = filter->sc_entry;
+			refcount_map = filter->sc_entry_refcount_map;
 			break;
 		case LTTNG_SYSCALL_ABI_COMPAT:
 			bitmap = filter->sc_compat_entry;
+			refcount_map = filter->sc_compat_entry_refcount_map;
 			break;
 		default:
 			return -EINVAL;
@@ -1401,9 +950,11 @@ int lttng_syscall_filter_enable(
 		switch (abi) {
 		case LTTNG_SYSCALL_ABI_NATIVE:
 			bitmap = filter->sc_exit;
+			refcount_map = filter->sc_exit_refcount_map;
 			break;
 		case LTTNG_SYSCALL_ABI_COMPAT:
 			bitmap = filter->sc_compat_exit;
+			refcount_map = filter->sc_compat_exit_refcount_map;
 			break;
 		default:
 			return -EINVAL;
@@ -1412,113 +963,122 @@ int lttng_syscall_filter_enable(
 	default:
 		return -EINVAL;
 	}
-	if (test_bit(syscall_nr, bitmap))
-		return -EEXIST;
-	bitmap_set(bitmap, syscall_nr, 1);
+	if (refcount_map[syscall_id] == U32_MAX)
+		return -EOVERFLOW;
+	if (refcount_map[syscall_id]++ == 0)
+		bitmap_set(bitmap, syscall_id, 1);
 	return 0;
 }
 
-int lttng_syscall_filter_enable_event_notifier(
-		struct lttng_kernel_event_notifier *event_notifier)
+int lttng_syscall_filter_enable_event(struct lttng_kernel_event_common *event)
 {
-	struct lttng_event_notifier_group *group = event_notifier->priv->group;
-	unsigned int syscall_id = event_notifier->priv->parent.u.syscall.syscall_id;
+	struct lttng_kernel_syscall_table *syscall_table = get_syscall_table_from_event(event);
+	unsigned int syscall_id = event->priv->u.syscall.syscall_id;
 	struct hlist_head *dispatch_list;
 	int ret = 0;
 
-	WARN_ON_ONCE(event_notifier->priv->parent.instrumentation != LTTNG_KERNEL_ABI_SYSCALL);
-
-	ret = lttng_syscall_filter_enable(group->sc_filter,
-		event_notifier->priv->parent.desc->event_name,
-		event_notifier->priv->parent.u.syscall.abi,
-		event_notifier->priv->parent.u.syscall.entryexit);
-	if (ret) {
-		goto end;
-	}
-
-	switch (event_notifier->priv->parent.u.syscall.entryexit) {
-	case LTTNG_SYSCALL_ENTRY:
-		switch (event_notifier->priv->parent.u.syscall.abi) {
-		case LTTNG_SYSCALL_ABI_NATIVE:
-			dispatch_list = &group->event_notifier_syscall_dispatch[syscall_id];
+	WARN_ON_ONCE(event->priv->instrumentation != LTTNG_KERNEL_ABI_SYSCALL);
+
+	/* Unknown syscall */
+	if (syscall_id == -1U) {
+		switch (event->priv->u.syscall.entryexit) {
+		case LTTNG_SYSCALL_ENTRY:
+			switch (event->priv->u.syscall.abi) {
+			case LTTNG_SYSCALL_ABI_NATIVE:
+				dispatch_list = &syscall_table->unknown_syscall_dispatch;
+				break;
+			case LTTNG_SYSCALL_ABI_COMPAT:
+				dispatch_list = &syscall_table->compat_unknown_syscall_dispatch;
+				break;
+			default:
+				ret = -EINVAL;
+				goto end;
+			}
 			break;
-		case LTTNG_SYSCALL_ABI_COMPAT:
-			dispatch_list = &group->event_notifier_compat_syscall_dispatch[syscall_id];
+		case LTTNG_SYSCALL_EXIT:
+			switch (event->priv->u.syscall.abi) {
+			case LTTNG_SYSCALL_ABI_NATIVE:
+				dispatch_list = &syscall_table->unknown_syscall_exit_dispatch;
+				break;
+			case LTTNG_SYSCALL_ABI_COMPAT:
+				dispatch_list = &syscall_table->compat_unknown_syscall_exit_dispatch;
+				break;
+			default:
+				ret = -EINVAL;
+				goto end;
+			}
 			break;
 		default:
 			ret = -EINVAL;
 			goto end;
 		}
-		break;
-	case LTTNG_SYSCALL_EXIT:
-		switch (event_notifier->priv->parent.u.syscall.abi) {
-		case LTTNG_SYSCALL_ABI_NATIVE:
-			dispatch_list = &group->event_notifier_exit_syscall_dispatch[syscall_id];
+	} else {
+		ret = lttng_syscall_filter_enable(syscall_table->sc_filter,
+			event->priv->desc->event_name, event->priv->u.syscall.abi,
+			event->priv->u.syscall.entryexit, syscall_id);
+		if (ret)
+			return ret;
+
+		switch (event->priv->u.syscall.entryexit) {
+		case LTTNG_SYSCALL_ENTRY:
+			switch (event->priv->u.syscall.abi) {
+			case LTTNG_SYSCALL_ABI_NATIVE:
+				dispatch_list = &syscall_table->syscall_dispatch[syscall_id];
+				break;
+			case LTTNG_SYSCALL_ABI_COMPAT:
+				dispatch_list = &syscall_table->compat_syscall_dispatch[syscall_id];
+				break;
+			default:
+				ret = -EINVAL;
+				goto end;
+			}
 			break;
-		case LTTNG_SYSCALL_ABI_COMPAT:
-			dispatch_list = &group->event_notifier_exit_compat_syscall_dispatch[syscall_id];
+		case LTTNG_SYSCALL_EXIT:
+			switch (event->priv->u.syscall.abi) {
+			case LTTNG_SYSCALL_ABI_NATIVE:
+				dispatch_list = &syscall_table->syscall_exit_dispatch[syscall_id];
+				break;
+			case LTTNG_SYSCALL_ABI_COMPAT:
+				dispatch_list = &syscall_table->compat_syscall_exit_dispatch[syscall_id];
+				break;
+			default:
+				ret = -EINVAL;
+				goto end;
+			}
 			break;
 		default:
 			ret = -EINVAL;
 			goto end;
 		}
-		break;
-	default:
-		ret = -EINVAL;
-		goto end;
 	}
 
-	hlist_add_head_rcu(&event_notifier->priv->parent.u.syscall.node, dispatch_list);
-
+	hlist_add_head_rcu(&event->priv->u.syscall.node, dispatch_list);
 end:
-	return ret ;
-}
-
-int lttng_syscall_filter_enable_event(
-		struct lttng_kernel_channel_buffer *channel,
-		struct lttng_kernel_event_recorder *event_recorder)
-{
-	WARN_ON_ONCE(event_recorder->priv->parent.instrumentation != LTTNG_KERNEL_ABI_SYSCALL);
-
-	return lttng_syscall_filter_enable(channel->priv->parent.sc_filter,
-		event_recorder->priv->parent.desc->event_name,
-		event_recorder->priv->parent.u.syscall.abi,
-		event_recorder->priv->parent.u.syscall.entryexit);
+	return ret;
 }
 
 static
-int lttng_syscall_filter_disable(
-		struct lttng_syscall_filter *filter,
+int lttng_syscall_filter_disable(struct lttng_syscall_filter *filter,
 		const char *desc_name, enum lttng_syscall_abi abi,
-		enum lttng_syscall_entryexit entryexit)
+		enum lttng_syscall_entryexit entryexit,
+		unsigned int syscall_id)
 {
 	const char *syscall_name;
 	unsigned long *bitmap;
-	int syscall_nr;
+	u32 *refcount_map;
 
 	syscall_name = get_syscall_name(desc_name, abi, entryexit);
 
-	switch (abi) {
-	case LTTNG_SYSCALL_ABI_NATIVE:
-		syscall_nr = get_syscall_nr(syscall_name);
-		break;
-	case LTTNG_SYSCALL_ABI_COMPAT:
-		syscall_nr = get_compat_syscall_nr(syscall_name);
-		break;
-	default:
-		return -EINVAL;
-	}
-	if (syscall_nr < 0)
-		return -ENOENT;
-
 	switch (entryexit) {
 	case LTTNG_SYSCALL_ENTRY:
 		switch (abi) {
 		case LTTNG_SYSCALL_ABI_NATIVE:
 			bitmap = filter->sc_entry;
+			refcount_map = filter->sc_entry_refcount_map;
 			break;
 		case LTTNG_SYSCALL_ABI_COMPAT:
 			bitmap = filter->sc_compat_entry;
+			refcount_map = filter->sc_compat_entry_refcount_map;
 			break;
 		default:
 			return -EINVAL;
@@ -1528,9 +1088,11 @@ int lttng_syscall_filter_disable(
 		switch (abi) {
 		case LTTNG_SYSCALL_ABI_NATIVE:
 			bitmap = filter->sc_exit;
+			refcount_map = filter->sc_exit_refcount_map;
 			break;
 		case LTTNG_SYSCALL_ABI_COMPAT:
 			bitmap = filter->sc_compat_exit;
+			refcount_map = filter->sc_compat_exit_refcount_map;
 			break;
 		default:
 			return -EINVAL;
@@ -1539,39 +1101,45 @@ int lttng_syscall_filter_disable(
 	default:
 		return -EINVAL;
 	}
-	if (!test_bit(syscall_nr, bitmap))
-		return -EEXIST;
-	bitmap_clear(bitmap, syscall_nr, 1);
-
+	if (refcount_map[syscall_id] == 0)
+		return -ENOENT;
+	if (--refcount_map[syscall_id] == 0)
+		bitmap_clear(bitmap, syscall_id, 1);
 	return 0;
 }
 
-int lttng_syscall_filter_disable_event_notifier(
-		struct lttng_kernel_event_notifier *event_notifier)
+int lttng_syscall_filter_disable_event(struct lttng_kernel_event_common *event)
 {
-	struct lttng_event_notifier_group *group = event_notifier->priv->group;
+	struct lttng_kernel_syscall_table *syscall_table = get_syscall_table_from_event(event);
+	unsigned int syscall_id = event->priv->u.syscall.syscall_id;
 	int ret;
 
-	WARN_ON_ONCE(event_notifier->priv->parent.instrumentation != LTTNG_KERNEL_ABI_SYSCALL);
-
-	ret = lttng_syscall_filter_disable(group->sc_filter,
-		event_notifier->priv->parent.desc->event_name,
-		event_notifier->priv->parent.u.syscall.abi,
-		event_notifier->priv->parent.u.syscall.entryexit);
-	WARN_ON_ONCE(ret != 0);
-
-	hlist_del_rcu(&event_notifier->priv->parent.u.syscall.node);
+	/* Except for unknown syscall */
+	if (syscall_id != -1U) {
+		ret = lttng_syscall_filter_disable(syscall_table->sc_filter,
+			event->priv->desc->event_name, event->priv->u.syscall.abi,
+			event->priv->u.syscall.entryexit, syscall_id);
+		if (ret)
+			return ret;
+	}
+	hlist_del_rcu(&event->priv->u.syscall.node);
 	return 0;
 }
 
-int lttng_syscall_filter_disable_event(
-		struct lttng_kernel_channel_buffer *channel,
-		struct lttng_kernel_event_recorder *event_recorder)
+void lttng_syscall_table_set_wildcard_all(struct lttng_event_enabler_common *event_enabler)
 {
-	return lttng_syscall_filter_disable(channel->priv->parent.sc_filter,
-		event_recorder->priv->parent.desc->event_name,
-		event_recorder->priv->parent.u.syscall.abi,
-		event_recorder->priv->parent.u.syscall.entryexit);
+	struct lttng_kernel_syscall_table *syscall_table = get_syscall_table_from_enabler(event_enabler);
+	enum lttng_kernel_abi_syscall_entryexit entryexit;
+	int enabled = event_enabler->enabled;
+
+	if (!lttng_syscall_event_enabler_is_wildcard_all(event_enabler))
+		return;
+	entryexit = event_enabler->event_param.u.syscall.entryexit;
+	if (entryexit == LTTNG_KERNEL_ABI_SYSCALL_ENTRY || entryexit == LTTNG_KERNEL_ABI_SYSCALL_ENTRYEXIT)
+		WRITE_ONCE(syscall_table->syscall_all_entry, enabled);
+
+	if (entryexit == LTTNG_KERNEL_ABI_SYSCALL_EXIT || entryexit == LTTNG_KERNEL_ABI_SYSCALL_ENTRYEXIT)
+		WRITE_ONCE(syscall_table->syscall_all_exit, enabled);
 }
 
 static
@@ -1688,7 +1256,7 @@ const struct file_operations lttng_syscall_list_fops = {
 /*
  * A syscall is enabled if it is traced for either entry or exit.
  */
-long lttng_channel_syscall_mask(struct lttng_kernel_channel_buffer *channel,
+long lttng_syscall_table_get_active_mask(struct lttng_kernel_syscall_table *syscall_table,
 		struct lttng_kernel_abi_syscall_mask __user *usyscall_mask)
 {
 	uint32_t len, sc_tables_len, bitmask_len;
@@ -1708,14 +1276,14 @@ long lttng_channel_syscall_mask(struct lttng_kernel_channel_buffer *channel,
 	tmp_mask = kzalloc(bitmask_len, GFP_KERNEL);
 	if (!tmp_mask)
 		return -ENOMEM;
-	filter = channel->priv->parent.sc_filter;
+	filter = syscall_table->sc_filter;
 
 	for (bit = 0; bit < sc_table.len; bit++) {
 		char state;
 
-		if (channel->priv->parent.sc_table) {
-			if (!(READ_ONCE(channel->priv->parent.syscall_all_entry)
-					|| READ_ONCE(channel->priv->parent.syscall_all_exit)) && filter)
+		if (syscall_table->syscall_dispatch) {
+			if (!(READ_ONCE(syscall_table->syscall_all_entry)
+					|| READ_ONCE(syscall_table->syscall_all_exit)) && filter)
 				state = test_bit(bit, filter->sc_entry)
 					|| test_bit(bit, filter->sc_exit);
 			else
@@ -1728,9 +1296,9 @@ long lttng_channel_syscall_mask(struct lttng_kernel_channel_buffer *channel,
 	for (; bit < sc_tables_len; bit++) {
 		char state;
 
-		if (channel->priv->parent.compat_sc_table) {
-			if (!(READ_ONCE(channel->priv->parent.syscall_all_entry)
-					|| READ_ONCE(channel->priv->parent.syscall_all_exit)) && filter)
+		if (syscall_table->compat_syscall_dispatch) {
+			if (!(READ_ONCE(syscall_table->syscall_all_entry)
+					|| READ_ONCE(syscall_table->syscall_all_exit)) && filter)
 				state = test_bit(bit - sc_table.len,
 						filter->sc_compat_entry)
 					|| test_bit(bit - sc_table.len,