Introduce lazy system call event creation
[lttng-modules.git] / src / lttng-events.c
index 246c71029dcc23d9f4dd602a645a5b069b0abcd1..3f9d0f9a91fdf7b50b7a647d1aea55413d8412b0 100644 (file)
@@ -36,7 +36,9 @@
 #include <wrapper/types.h>
 #include <lttng/kernel-version.h>
 #include <lttng/events.h>
+#include <lttng/lttng-bytecode.h>
 #include <lttng/tracer.h>
+#include <lttng/event-notifier-notification.h>
 #include <lttng/abi-old.h>
 #include <lttng/endian.h>
 #include <lttng/string-utils.h>
 static LIST_HEAD(sessions);
 static LIST_HEAD(event_notifier_groups);
 static LIST_HEAD(lttng_transport_list);
+static LIST_HEAD(lttng_counter_transport_list);
 /*
  * Protect the sessions and metadata caches.
  */
 static DEFINE_MUTEX(sessions_mutex);
 static struct kmem_cache *event_cache;
+static struct kmem_cache *event_notifier_cache;
 
 static void lttng_session_lazy_sync_event_enablers(struct lttng_session *session);
 static void lttng_session_sync_event_enablers(struct lttng_session *session);
 static void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler);
+static void lttng_event_notifier_enabler_destroy(struct lttng_event_notifier_enabler *event_notifier_enabler);
+static void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group);
 
 static void _lttng_event_destroy(struct lttng_event *event);
+static void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier);
 static void _lttng_channel_destroy(struct lttng_channel *chan);
 static int _lttng_event_unregister(struct lttng_event *event);
+static int _lttng_event_notifier_unregister(struct lttng_event_notifier *event_notifier);
 static
 int _lttng_event_metadata_statedump(struct lttng_session *session,
                                  struct lttng_channel *chan,
@@ -190,6 +198,61 @@ err:
        return NULL;
 }
 
+static
+struct lttng_counter_transport *lttng_counter_transport_find(const char *name)
+{
+       struct lttng_counter_transport *transport;
+
+       list_for_each_entry(transport, &lttng_counter_transport_list, node) {
+               if (!strcmp(transport->name, name))
+                       return transport;
+       }
+       return NULL;
+}
+
+struct lttng_counter *lttng_kernel_counter_create(
+               const char *counter_transport_name,
+               size_t number_dimensions, const size_t *dimensions_sizes)
+{
+       struct lttng_counter *counter = NULL;
+       struct lttng_counter_transport *counter_transport = NULL;
+
+       counter_transport = lttng_counter_transport_find(counter_transport_name);
+       if (!counter_transport) {
+               printk(KERN_WARNING "LTTng: counter transport %s not found.\n",
+                      counter_transport_name);
+               goto notransport;
+       }
+       if (!try_module_get(counter_transport->owner)) {
+               printk(KERN_WARNING "LTTng: Can't lock counter transport module.\n");
+               goto notransport;
+       }
+
+       counter = lttng_kvzalloc(sizeof(struct lttng_counter), GFP_KERNEL);
+       if (!counter)
+               goto nomem;
+
+       /* Create event notifier error counter. */
+       counter->ops = &counter_transport->ops;
+       counter->transport = counter_transport;
+
+       counter->counter = counter->ops->counter_create(
+                       number_dimensions, dimensions_sizes, 0);
+       if (!counter->counter) {
+               goto create_error;
+       }
+
+       return counter;
+
+create_error:
+       lttng_kvfree(counter);
+nomem:
+       if (counter_transport)
+               module_put(counter_transport->owner);
+notransport:
+       return NULL;
+}
+
 struct lttng_event_notifier_group *lttng_event_notifier_group_create(void)
 {
        struct lttng_transport *transport = NULL;
@@ -199,6 +262,7 @@ struct lttng_event_notifier_group *lttng_event_notifier_group_create(void)
        size_t num_subbuf = 16;         //TODO
        unsigned int switch_timer_interval = 0;
        unsigned int read_timer_interval = 0;
+       int i;
 
        mutex_lock(&sessions_mutex);
 
@@ -232,6 +296,12 @@ struct lttng_event_notifier_group *lttng_event_notifier_group_create(void)
                goto create_error;
 
        event_notifier_group->transport = transport;
+
+       INIT_LIST_HEAD(&event_notifier_group->enablers_head);
+       INIT_LIST_HEAD(&event_notifier_group->event_notifiers_head);
+       for (i = 0; i < LTTNG_EVENT_NOTIFIER_HT_SIZE; i++)
+               INIT_HLIST_HEAD(&event_notifier_group->event_notifiers_ht.table[i]);
+
        list_add(&event_notifier_group->node, &event_notifier_groups);
 
        mutex_unlock(&sessions_mutex);
@@ -267,7 +337,7 @@ void lttng_session_destroy(struct lttng_session *session)
        mutex_lock(&sessions_mutex);
        WRITE_ONCE(session->active, 0);
        list_for_each_entry(chan, &session->chan, list) {
-               ret = lttng_syscalls_unregister(chan);
+               ret = lttng_syscalls_unregister_channel(chan);
                WARN_ON(ret);
        }
        list_for_each_entry(event, &session->events, list) {
@@ -276,7 +346,7 @@ void lttng_session_destroy(struct lttng_session *session)
        }
        synchronize_trace();    /* Wait for in-flight events to complete */
        list_for_each_entry(chan, &session->chan, list) {
-               ret = lttng_syscalls_destroy(chan);
+               ret = lttng_syscalls_destroy_event(chan);
                WARN_ON(ret);
        }
        list_for_each_entry_safe(event_enabler, tmp_event_enabler,
@@ -304,15 +374,54 @@ void lttng_session_destroy(struct lttng_session *session)
        lttng_kvfree(session);
 }
 
-void lttng_event_notifier_group_destroy(struct lttng_event_notifier_group *event_notifier_group)
+void lttng_event_notifier_group_destroy(
+               struct lttng_event_notifier_group *event_notifier_group)
 {
+       struct lttng_event_notifier_enabler *event_notifier_enabler, *tmp_event_notifier_enabler;
+       struct lttng_event_notifier *event_notifier, *tmpevent_notifier;
+       int ret;
+
        if (!event_notifier_group)
                return;
 
        mutex_lock(&sessions_mutex);
+
+       ret = lttng_syscalls_unregister_event_notifier_group(event_notifier_group);
+       WARN_ON(ret);
+
+       list_for_each_entry_safe(event_notifier, tmpevent_notifier,
+                       &event_notifier_group->event_notifiers_head, list) {
+               ret = _lttng_event_notifier_unregister(event_notifier);
+               WARN_ON(ret);
+       }
+
+       /* Wait for in-flight event notifier to complete */
+       synchronize_trace();
+
+       irq_work_sync(&event_notifier_group->wakeup_pending);
+
+       kfree(event_notifier_group->sc_filter);
+
+       list_for_each_entry_safe(event_notifier_enabler, tmp_event_notifier_enabler,
+                       &event_notifier_group->enablers_head, node)
+               lttng_event_notifier_enabler_destroy(event_notifier_enabler);
+
+       list_for_each_entry_safe(event_notifier, tmpevent_notifier,
+                       &event_notifier_group->event_notifiers_head, list)
+               _lttng_event_notifier_destroy(event_notifier);
+
+       if (event_notifier_group->error_counter) {
+               struct lttng_counter *error_counter = event_notifier_group->error_counter;
+               error_counter->ops->counter_destroy(error_counter->counter);
+               module_put(error_counter->transport->owner);
+               lttng_kvfree(error_counter);
+               event_notifier_group->error_counter = NULL;
+       }
+
        event_notifier_group->ops->channel_destroy(event_notifier_group->chan);
        module_put(event_notifier_group->transport->owner);
        list_del(&event_notifier_group->node);
+
        mutex_unlock(&sessions_mutex);
        lttng_kvfree(event_notifier_group);
 }
@@ -562,6 +671,66 @@ end:
        return ret;
 }
 
+int lttng_event_notifier_enable(struct lttng_event_notifier *event_notifier)
+{
+       int ret = 0;
+
+       mutex_lock(&sessions_mutex);
+       if (event_notifier->enabled) {
+               ret = -EEXIST;
+               goto end;
+       }
+       switch (event_notifier->instrumentation) {
+       case LTTNG_KERNEL_TRACEPOINT:
+       case LTTNG_KERNEL_SYSCALL:
+               ret = -EINVAL;
+               break;
+       case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
+               WRITE_ONCE(event_notifier->enabled, 1);
+               break;
+       case LTTNG_KERNEL_FUNCTION:
+       case LTTNG_KERNEL_NOOP:
+       case LTTNG_KERNEL_KRETPROBE:
+       default:
+               WARN_ON_ONCE(1);
+               ret = -EINVAL;
+       }
+end:
+       mutex_unlock(&sessions_mutex);
+       return ret;
+}
+
+int lttng_event_notifier_disable(struct lttng_event_notifier *event_notifier)
+{
+       int ret = 0;
+
+       mutex_lock(&sessions_mutex);
+       if (!event_notifier->enabled) {
+               ret = -EEXIST;
+               goto end;
+       }
+       switch (event_notifier->instrumentation) {
+       case LTTNG_KERNEL_TRACEPOINT:
+       case LTTNG_KERNEL_SYSCALL:
+               ret = -EINVAL;
+               break;
+       case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
+               WRITE_ONCE(event_notifier->enabled, 0);
+               break;
+       case LTTNG_KERNEL_FUNCTION:
+       case LTTNG_KERNEL_NOOP:
+       case LTTNG_KERNEL_KRETPROBE:
+       default:
+               WARN_ON_ONCE(1);
+               ret = -EINVAL;
+       }
+end:
+       mutex_unlock(&sessions_mutex);
+       return ret;
+}
+
 struct lttng_channel *lttng_channel_create(struct lttng_session *session,
                                       const char *transport_name,
                                       void *buf_addr,
@@ -654,6 +823,7 @@ void _lttng_metadata_channel_hangup(struct lttng_metadata_stream *stream)
        wake_up_interruptible(&stream->read_wait);
 }
 
+
 /*
  * Supports event creation while tracing session is active.
  * Needs to be called with sessions mutex held.
@@ -715,7 +885,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
        event->id = chan->free_event_id++;
        event->instrumentation = itype;
        event->evtype = LTTNG_TYPE_EVENT;
-       INIT_LIST_HEAD(&event->bytecode_runtime_head);
+       INIT_LIST_HEAD(&event->filter_bytecode_runtime_head);
        INIT_LIST_HEAD(&event->enablers_ref_head);
 
        switch (itype) {
@@ -743,7 +913,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
                 * registration.
                 */
                smp_wmb();
-               ret = lttng_kprobes_register(event_name,
+               ret = lttng_kprobes_register_event(event_name,
                                event_param->u.kprobe.symbol_name,
                                event_param->u.kprobe.offset,
                                event_param->u.kprobe.addr,
@@ -859,7 +1029,7 @@ struct lttng_event *_lttng_event_create(struct lttng_channel *chan,
                 */
                smp_wmb();
 
-               ret = lttng_uprobes_register(event_param->name,
+               ret = lttng_uprobes_register_event(event_param->name,
                                event_param->u.uprobe.fd,
                                event);
                if (ret)
@@ -893,6 +1063,235 @@ full:
        return ERR_PTR(ret);
 }
 
+struct lttng_event_notifier *_lttng_event_notifier_create(
+               const struct lttng_event_desc *event_desc,
+               uint64_t token, uint64_t error_counter_index,
+               struct lttng_event_notifier_group *event_notifier_group,
+               struct lttng_kernel_event_notifier *event_notifier_param,
+               void *filter, enum lttng_kernel_instrumentation itype)
+{
+       struct lttng_event_notifier *event_notifier;
+       const char *event_name;
+       struct hlist_head *head;
+       int ret;
+
+       switch (itype) {
+       case LTTNG_KERNEL_TRACEPOINT:
+               event_name = event_desc->name;
+               break;
+       case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
+       case LTTNG_KERNEL_SYSCALL:
+               event_name = event_notifier_param->event.name;
+               break;
+       case LTTNG_KERNEL_KRETPROBE:
+       case LTTNG_KERNEL_FUNCTION:
+       case LTTNG_KERNEL_NOOP:
+       default:
+               WARN_ON_ONCE(1);
+               ret = -EINVAL;
+               goto type_error;
+       }
+
+       head = utils_borrow_hash_table_bucket(event_notifier_group->event_notifiers_ht.table,
+               LTTNG_EVENT_NOTIFIER_HT_SIZE, event_name);
+       lttng_hlist_for_each_entry(event_notifier, head, hlist) {
+               WARN_ON_ONCE(!event_notifier->desc);
+               if (!strncmp(event_notifier->desc->name, event_name,
+                                       LTTNG_KERNEL_SYM_NAME_LEN - 1)
+                               && event_notifier_group == event_notifier->group
+                               && token == event_notifier->user_token) {
+                       ret = -EEXIST;
+                       goto exist;
+               }
+       }
+
+       event_notifier = kmem_cache_zalloc(event_notifier_cache, GFP_KERNEL);
+       if (!event_notifier) {
+               ret = -ENOMEM;
+               goto cache_error;
+       }
+
+       event_notifier->group = event_notifier_group;
+       event_notifier->user_token = token;
+       event_notifier->error_counter_index = error_counter_index;
+       event_notifier->num_captures = 0;
+       event_notifier->filter = filter;
+       event_notifier->instrumentation = itype;
+       event_notifier->evtype = LTTNG_TYPE_EVENT;
+       event_notifier->send_notification = lttng_event_notifier_notification_send;
+       INIT_LIST_HEAD(&event_notifier->filter_bytecode_runtime_head);
+       INIT_LIST_HEAD(&event_notifier->capture_bytecode_runtime_head);
+       INIT_LIST_HEAD(&event_notifier->enablers_ref_head);
+
+       switch (itype) {
+       case LTTNG_KERNEL_TRACEPOINT:
+               /* Event will be enabled by enabler sync. */
+               event_notifier->enabled = 0;
+               event_notifier->registered = 0;
+               event_notifier->desc = lttng_event_desc_get(event_name);
+               if (!event_notifier->desc) {
+                       ret = -ENOENT;
+                       goto register_error;
+               }
+               /* Populate lttng_event_notifier structure before event registration. */
+               smp_wmb();
+               break;
+       case LTTNG_KERNEL_KPROBE:
+               /*
+                * Needs to be explicitly enabled after creation, since
+                * we may want to apply filters.
+                */
+               event_notifier->enabled = 0;
+               event_notifier->registered = 1;
+               /*
+                * Populate lttng_event_notifier structure before event
+                * registration.
+                */
+               smp_wmb();
+               ret = lttng_kprobes_register_event_notifier(
+                               event_notifier_param->event.u.kprobe.symbol_name,
+                               event_notifier_param->event.u.kprobe.offset,
+                               event_notifier_param->event.u.kprobe.addr,
+                               event_notifier);
+               if (ret) {
+                       ret = -EINVAL;
+                       goto register_error;
+               }
+               ret = try_module_get(event_notifier->desc->owner);
+               WARN_ON_ONCE(!ret);
+               break;
+       case LTTNG_KERNEL_NOOP:
+       case LTTNG_KERNEL_SYSCALL:
+               /*
+                * Needs to be explicitly enabled after creation, since
+                * we may want to apply filters.
+                */
+               event_notifier->enabled = 0;
+               event_notifier->registered = 0;
+               event_notifier->desc = event_desc;
+               switch (event_notifier_param->event.u.syscall.entryexit) {
+               case LTTNG_KERNEL_SYSCALL_ENTRYEXIT:
+                       ret = -EINVAL;
+                       goto register_error;
+               case LTTNG_KERNEL_SYSCALL_ENTRY:
+                       event_notifier->u.syscall.entryexit = LTTNG_SYSCALL_ENTRY;
+                       break;
+               case LTTNG_KERNEL_SYSCALL_EXIT:
+                       event_notifier->u.syscall.entryexit = LTTNG_SYSCALL_EXIT;
+                       break;
+               }
+               switch (event_notifier_param->event.u.syscall.abi) {
+               case LTTNG_KERNEL_SYSCALL_ABI_ALL:
+                       ret = -EINVAL;
+                       goto register_error;
+               case LTTNG_KERNEL_SYSCALL_ABI_NATIVE:
+                       event_notifier->u.syscall.abi = LTTNG_SYSCALL_ABI_NATIVE;
+                       break;
+               case LTTNG_KERNEL_SYSCALL_ABI_COMPAT:
+                       event_notifier->u.syscall.abi = LTTNG_SYSCALL_ABI_COMPAT;
+                       break;
+               }
+
+               if (!event_notifier->desc) {
+                       ret = -EINVAL;
+                       goto register_error;
+               }
+               break;
+       case LTTNG_KERNEL_UPROBE:
+               /*
+                * Needs to be explicitly enabled after creation, since
+                * we may want to apply filters.
+                */
+               event_notifier->enabled = 0;
+               event_notifier->registered = 1;
+
+               /*
+                * Populate lttng_event_notifier structure before
+                * event_notifier registration.
+                */
+               smp_wmb();
+
+               ret = lttng_uprobes_register_event_notifier(
+                               event_notifier_param->event.name,
+                               event_notifier_param->event.u.uprobe.fd,
+                               event_notifier);
+               if (ret)
+                       goto register_error;
+               ret = try_module_get(event_notifier->desc->owner);
+               WARN_ON_ONCE(!ret);
+               break;
+       case LTTNG_KERNEL_KRETPROBE:
+       case LTTNG_KERNEL_FUNCTION:
+       default:
+               WARN_ON_ONCE(1);
+               ret = -EINVAL;
+               goto register_error;
+       }
+
+       list_add(&event_notifier->list, &event_notifier_group->event_notifiers_head);
+       hlist_add_head(&event_notifier->hlist, head);
+
+       /*
+        * Clear the error counter bucket. The sessiond keeps track of which
+        * bucket is currently in use. We trust it.
+        */
+       if (event_notifier_group->error_counter) {
+               size_t dimension_index[1];
+
+               /*
+                * Check that the index is within the boundary of the counter.
+                */
+               if (event_notifier->error_counter_index >= event_notifier_group->error_counter_len) {
+                       printk(KERN_INFO "LTTng: event_notifier: Error counter index out-of-bound: counter-len=%zu, index=%llu\n",
+                               event_notifier_group->error_counter_len, event_notifier->error_counter_index);
+                       ret = -EINVAL;
+                       goto register_error;
+               }
+
+               dimension_index[0] = event_notifier->error_counter_index;
+               ret = event_notifier_group->error_counter->ops->counter_clear(
+                               event_notifier_group->error_counter->counter,
+                               dimension_index);
+               if (ret) {
+                       printk(KERN_INFO "LTTng: event_notifier: Unable to clear error counter bucket %llu\n",
+                               event_notifier->error_counter_index);
+                       goto register_error;
+               }
+       }
+
+       return event_notifier;
+
+register_error:
+       kmem_cache_free(event_notifier_cache, event_notifier);
+cache_error:
+exist:
+type_error:
+       return ERR_PTR(ret);
+}
+
+int lttng_kernel_counter_read(struct lttng_counter *counter,
+               const size_t *dim_indexes, int32_t cpu,
+               int64_t *val, bool *overflow, bool *underflow)
+{
+       return counter->ops->counter_read(counter->counter, dim_indexes,
+                       cpu, val, overflow, underflow);
+}
+
+int lttng_kernel_counter_aggregate(struct lttng_counter *counter,
+               const size_t *dim_indexes, int64_t *val,
+               bool *overflow, bool *underflow)
+{
+       return counter->ops->counter_aggregate(counter->counter, dim_indexes,
+                       val, overflow, underflow);
+}
+
+int lttng_kernel_counter_clear(struct lttng_counter *counter,
+               const size_t *dim_indexes)
+{
+       return counter->ops->counter_clear(counter->counter, dim_indexes);
+}
+
 struct lttng_event *lttng_event_create(struct lttng_channel *chan,
                                struct lttng_kernel_event *event_param,
                                void *filter,
@@ -908,6 +1307,23 @@ struct lttng_event *lttng_event_create(struct lttng_channel *chan,
        return event;
 }
 
+struct lttng_event_notifier *lttng_event_notifier_create(
+               const struct lttng_event_desc *event_desc,
+               uint64_t id, uint64_t error_counter_index,
+               struct lttng_event_notifier_group *event_notifier_group,
+               struct lttng_kernel_event_notifier *event_notifier_param,
+               void *filter, enum lttng_kernel_instrumentation itype)
+{
+       struct lttng_event_notifier *event_notifier;
+
+       mutex_lock(&sessions_mutex);
+       event_notifier = _lttng_event_notifier_create(event_desc, id,
+               error_counter_index, event_notifier_group,
+               event_notifier_param, filter, itype);
+       mutex_unlock(&sessions_mutex);
+       return event_notifier;
+}
+
 /* Only used for tracepoints for now. */
 static
 void register_event(struct lttng_event *event)
@@ -926,7 +1342,7 @@ void register_event(struct lttng_event *event)
                                                  event);
                break;
        case LTTNG_KERNEL_SYSCALL:
-               ret = lttng_syscall_filter_enable(event->chan, event);
+               ret = lttng_syscall_filter_enable_event(event->chan, event);
                break;
        case LTTNG_KERNEL_KPROBE:
        case LTTNG_KERNEL_UPROBE:
@@ -961,7 +1377,7 @@ int _lttng_event_unregister(struct lttng_event *event)
                                                  event);
                break;
        case LTTNG_KERNEL_KPROBE:
-               lttng_kprobes_unregister(event);
+               lttng_kprobes_unregister_event(event);
                ret = 0;
                break;
        case LTTNG_KERNEL_KRETPROBE:
@@ -969,13 +1385,13 @@ int _lttng_event_unregister(struct lttng_event *event)
                ret = 0;
                break;
        case LTTNG_KERNEL_SYSCALL:
-               ret = lttng_syscall_filter_disable(event->chan, event);
+               ret = lttng_syscall_filter_disable_event(event->chan, event);
                break;
        case LTTNG_KERNEL_NOOP:
                ret = 0;
                break;
        case LTTNG_KERNEL_UPROBE:
-               lttng_uprobes_unregister(event);
+               lttng_uprobes_unregister_event(event);
                ret = 0;
                break;
        case LTTNG_KERNEL_FUNCTION:     /* Fall-through */
@@ -987,6 +1403,79 @@ int _lttng_event_unregister(struct lttng_event *event)
        return ret;
 }
 
+/* Only used for tracepoints for now. */
+static
+void register_event_notifier(struct lttng_event_notifier *event_notifier)
+{
+       const struct lttng_event_desc *desc;
+       int ret = -EINVAL;
+
+       if (event_notifier->registered)
+               return;
+
+       desc = event_notifier->desc;
+       switch (event_notifier->instrumentation) {
+       case LTTNG_KERNEL_TRACEPOINT:
+               ret = lttng_wrapper_tracepoint_probe_register(desc->kname,
+                                                 desc->event_notifier_callback,
+                                                 event_notifier);
+               break;
+       case LTTNG_KERNEL_SYSCALL:
+               ret = lttng_syscall_filter_enable_event_notifier(event_notifier);
+               break;
+       case LTTNG_KERNEL_KPROBE:
+       case LTTNG_KERNEL_UPROBE:
+               ret = 0;
+               break;
+       case LTTNG_KERNEL_KRETPROBE:
+       case LTTNG_KERNEL_FUNCTION:
+       case LTTNG_KERNEL_NOOP:
+       default:
+               WARN_ON_ONCE(1);
+       }
+       if (!ret)
+               event_notifier->registered = 1;
+}
+
+static
+int _lttng_event_notifier_unregister(
+               struct lttng_event_notifier *event_notifier)
+{
+       const struct lttng_event_desc *desc;
+       int ret = -EINVAL;
+
+       if (!event_notifier->registered)
+               return 0;
+
+       desc = event_notifier->desc;
+       switch (event_notifier->instrumentation) {
+       case LTTNG_KERNEL_TRACEPOINT:
+               ret = lttng_wrapper_tracepoint_probe_unregister(event_notifier->desc->kname,
+                                                 event_notifier->desc->event_notifier_callback,
+                                                 event_notifier);
+               break;
+       case LTTNG_KERNEL_KPROBE:
+               lttng_kprobes_unregister_event_notifier(event_notifier);
+               ret = 0;
+               break;
+       case LTTNG_KERNEL_UPROBE:
+               lttng_uprobes_unregister_event_notifier(event_notifier);
+               ret = 0;
+               break;
+       case LTTNG_KERNEL_SYSCALL:
+               ret = lttng_syscall_filter_disable_event_notifier(event_notifier);
+               break;
+       case LTTNG_KERNEL_KRETPROBE:
+       case LTTNG_KERNEL_FUNCTION:
+       case LTTNG_KERNEL_NOOP:
+       default:
+               WARN_ON_ONCE(1);
+       }
+       if (!ret)
+               event_notifier->registered = 0;
+       return ret;
+}
+
 /*
  * Only used internally at session destruction.
  */
@@ -999,7 +1488,7 @@ void _lttng_event_destroy(struct lttng_event *event)
                break;
        case LTTNG_KERNEL_KPROBE:
                module_put(event->desc->owner);
-               lttng_kprobes_destroy_private(event);
+               lttng_kprobes_destroy_event_private(event);
                break;
        case LTTNG_KERNEL_KRETPROBE:
                module_put(event->desc->owner);
@@ -1010,7 +1499,7 @@ void _lttng_event_destroy(struct lttng_event *event)
                break;
        case LTTNG_KERNEL_UPROBE:
                module_put(event->desc->owner);
-               lttng_uprobes_destroy_private(event);
+               lttng_uprobes_destroy_event_private(event);
                break;
        case LTTNG_KERNEL_FUNCTION:     /* Fall-through */
        default:
@@ -1021,6 +1510,36 @@ void _lttng_event_destroy(struct lttng_event *event)
        kmem_cache_free(event_cache, event);
 }
 
+/*
+ * Only used internally at session destruction.
+ */
+static
+void _lttng_event_notifier_destroy(struct lttng_event_notifier *event_notifier)
+{
+       switch (event_notifier->instrumentation) {
+       case LTTNG_KERNEL_TRACEPOINT:
+               lttng_event_desc_put(event_notifier->desc);
+               break;
+       case LTTNG_KERNEL_KPROBE:
+               module_put(event_notifier->desc->owner);
+               lttng_kprobes_destroy_event_notifier_private(event_notifier);
+               break;
+       case LTTNG_KERNEL_NOOP:
+       case LTTNG_KERNEL_SYSCALL:
+               break;
+       case LTTNG_KERNEL_UPROBE:
+               module_put(event_notifier->desc->owner);
+               lttng_uprobes_destroy_event_notifier_private(event_notifier);
+               break;
+       case LTTNG_KERNEL_KRETPROBE:
+       case LTTNG_KERNEL_FUNCTION:
+       default:
+               WARN_ON_ONCE(1);
+       }
+       list_del(&event_notifier->list);
+       kmem_cache_free(event_notifier_cache, event_notifier);
+}
+
 struct lttng_id_tracker *get_tracker(struct lttng_session *session,
                enum tracker_type tracker_type)
 {
@@ -1296,7 +1815,6 @@ int lttng_match_enabler_name(const char *desc_name,
        return 1;
 }
 
-static
 int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
                struct lttng_enabler *enabler)
 {
@@ -1362,7 +1880,7 @@ int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
                        return -EINVAL;
                }
                switch (enabler->event_param.u.syscall.match) {
-               case LTTNG_SYSCALL_MATCH_NAME:
+               case LTTNG_KERNEL_SYSCALL_MATCH_NAME:
                        switch (enabler->format_type) {
                        case LTTNG_ENABLER_FORMAT_STAR_GLOB:
                                return lttng_match_enabler_star_glob(desc_name, enabler_name);
@@ -1372,7 +1890,7 @@ int lttng_desc_match_enabler(const struct lttng_event_desc *desc,
                                return -EINVAL;
                        }
                        break;
-               case LTTNG_SYSCALL_MATCH_NR:
+               case LTTNG_KERNEL_SYSCALL_MATCH_NR:
                        return -EINVAL; /* Not implemented. */
                default:
                        return -EINVAL;
@@ -1400,6 +1918,23 @@ int lttng_event_enabler_match_event(struct lttng_event_enabler *event_enabler,
                return 0;
 }
 
+static
+int lttng_event_notifier_enabler_match_event_notifier(struct lttng_event_notifier_enabler *event_notifier_enabler,
+               struct lttng_event_notifier *event_notifier)
+{
+       struct lttng_enabler *base_enabler = lttng_event_notifier_enabler_as_enabler(
+               event_notifier_enabler);
+
+       if (base_enabler->event_param.instrumentation != event_notifier->instrumentation)
+               return 0;
+       if (lttng_desc_match_enabler(event_notifier->desc, base_enabler)
+                       && event_notifier->group == event_notifier_enabler->group
+                       && event_notifier->user_token == event_notifier_enabler->base.user_token)
+               return 1;
+       else
+               return 0;
+}
+
 static
 struct lttng_enabler_ref *lttng_enabler_ref(
                struct list_head *enablers_ref_list,
@@ -1433,36 +1968,92 @@ void lttng_create_tracepoint_event_if_missing(struct lttng_event_enabler *event_
                for (i = 0; i < probe_desc->nr_events; i++) {
                        int found = 0;
                        struct hlist_head *head;
-                       struct lttng_event *event;
+                       struct lttng_event *event;
+
+                       desc = probe_desc->event_desc[i];
+                       if (!lttng_desc_match_enabler(desc,
+                                       lttng_event_enabler_as_enabler(event_enabler)))
+                               continue;
+
+                       /*
+                        * Check if already created.
+                        */
+                       head = utils_borrow_hash_table_bucket(
+                               session->events_ht.table, LTTNG_EVENT_HT_SIZE,
+                               desc->name);
+                       lttng_hlist_for_each_entry(event, head, hlist) {
+                               if (event->desc == desc
+                                               && event->chan == event_enabler->chan)
+                                       found = 1;
+                       }
+                       if (found)
+                               continue;
+
+                       /*
+                        * We need to create an event for this
+                        * event probe.
+                        */
+                       event = _lttng_event_create(event_enabler->chan,
+                                       NULL, NULL, desc,
+                                       LTTNG_KERNEL_TRACEPOINT);
+                       if (!event) {
+                               printk(KERN_INFO "LTTng: Unable to create event %s\n",
+                                       probe_desc->event_desc[i]->name);
+                       }
+               }
+       }
+}
+
+static
+void lttng_create_tracepoint_event_notifier_if_missing(struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+       struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
+       struct lttng_probe_desc *probe_desc;
+       const struct lttng_event_desc *desc;
+       int i;
+       struct list_head *probe_list;
+
+       probe_list = lttng_get_probe_list_head();
+       /*
+        * For each probe event, if we find that a probe event matches
+        * our enabler, create an associated lttng_event_notifier if not
+        * already present.
+        */
+       list_for_each_entry(probe_desc, probe_list, head) {
+               for (i = 0; i < probe_desc->nr_events; i++) {
+                       int found = 0;
+                       struct hlist_head *head;
+                       struct lttng_event_notifier *event_notifier;
 
                        desc = probe_desc->event_desc[i];
                        if (!lttng_desc_match_enabler(desc,
-                                       lttng_event_enabler_as_enabler(event_enabler)))
+                                       lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)))
                                continue;
 
                        /*
                         * Check if already created.
                         */
                        head = utils_borrow_hash_table_bucket(
-                               session->events_ht.table, LTTNG_EVENT_HT_SIZE,
-                               desc->name);
-                       lttng_hlist_for_each_entry(event, head, hlist) {
-                               if (event->desc == desc
-                                               && event->chan == event_enabler->chan)
+                               event_notifier_group->event_notifiers_ht.table,
+                               LTTNG_EVENT_NOTIFIER_HT_SIZE, desc->name);
+                       lttng_hlist_for_each_entry(event_notifier, head, hlist) {
+                               if (event_notifier->desc == desc
+                                               && event_notifier->user_token == event_notifier_enabler->base.user_token)
                                        found = 1;
                        }
                        if (found)
                                continue;
 
                        /*
-                        * We need to create an event for this
-                        * event probe.
+                        * We need to create a event_notifier for this event probe.
                         */
-                       event = _lttng_event_create(event_enabler->chan,
-                                       NULL, NULL, desc,
-                                       LTTNG_KERNEL_TRACEPOINT);
-                       if (!event) {
-                               printk(KERN_INFO "LTTng: Unable to create event %s\n",
+                       event_notifier = _lttng_event_notifier_create(desc,
+                               event_notifier_enabler->base.user_token,
+                               event_notifier_enabler->error_counter_index,
+                               event_notifier_group, NULL, NULL,
+                               LTTNG_KERNEL_TRACEPOINT);
+                       if (IS_ERR(event_notifier)) {
+                               printk(KERN_INFO "Unable to create event_notifier %s\n",
                                        probe_desc->event_desc[i]->name);
                        }
                }
@@ -1474,7 +2065,18 @@ void lttng_create_syscall_event_if_missing(struct lttng_event_enabler *event_ena
 {
        int ret;
 
-       ret = lttng_syscalls_register(event_enabler->chan, NULL);
+       ret = lttng_syscalls_register_event(event_enabler, NULL);
+       WARN_ON_ONCE(ret);
+}
+
+static
+void lttng_create_syscall_event_notifier_if_missing(struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+       int ret;
+
+       ret = lttng_syscalls_register_event_notifier(event_notifier_enabler, NULL);
+       WARN_ON_ONCE(ret);
+       ret = lttng_syscals_create_matching_event_notifiers(event_notifier_enabler, NULL);
        WARN_ON_ONCE(ret);
 }
 
@@ -1513,14 +2115,17 @@ int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
        struct lttng_event *event;
 
        if (base_enabler->event_param.instrumentation == LTTNG_KERNEL_SYSCALL &&
-                       base_enabler->event_param.u.syscall.entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT &&
                        base_enabler->event_param.u.syscall.abi == LTTNG_KERNEL_SYSCALL_ABI_ALL &&
-                       base_enabler->event_param.u.syscall.match == LTTNG_SYSCALL_MATCH_NAME &&
+                       base_enabler->event_param.u.syscall.match == LTTNG_KERNEL_SYSCALL_MATCH_NAME &&
                        !strcmp(base_enabler->event_param.name, "*")) {
-               if (base_enabler->enabled)
-                       WRITE_ONCE(chan->syscall_all, 1);
-               else
-                       WRITE_ONCE(chan->syscall_all, 0);
+               int enabled = base_enabler->enabled;
+               enum lttng_kernel_syscall_entryexit entryexit = base_enabler->event_param.u.syscall.entryexit;
+
+               if (entryexit == LTTNG_KERNEL_SYSCALL_ENTRY || entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT)
+                       WRITE_ONCE(chan->syscall_all_entry, enabled);
+
+               if (entryexit == LTTNG_KERNEL_SYSCALL_EXIT || entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT)
+                       WRITE_ONCE(chan->syscall_all_exit, enabled);
        }
 
        /* First ensure that probe events are created for this enabler. */
@@ -1552,14 +2157,106 @@ int lttng_event_enabler_ref_events(struct lttng_event_enabler *event_enabler)
                 */
                lttng_enabler_link_bytecode(event->desc,
                        lttng_static_ctx,
-                       &event->bytecode_runtime_head,
-                       lttng_event_enabler_as_enabler(event_enabler));
+                       &event->filter_bytecode_runtime_head,
+                       &lttng_event_enabler_as_enabler(event_enabler)->filter_bytecode_head);
 
                /* TODO: merge event context. */
        }
        return 0;
 }
 
+/*
+ * Create struct lttng_event_notifier if it is missing and present in the list of
+ * tracepoint probes.
+ * Should be called with sessions mutex held.
+ */
+static
+void lttng_create_event_notifier_if_missing(struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+       switch (event_notifier_enabler->base.event_param.instrumentation) {
+       case LTTNG_KERNEL_TRACEPOINT:
+               lttng_create_tracepoint_event_notifier_if_missing(event_notifier_enabler);
+               break;
+       case LTTNG_KERNEL_SYSCALL:
+               lttng_create_syscall_event_notifier_if_missing(event_notifier_enabler);
+               break;
+       default:
+               WARN_ON_ONCE(1);
+               break;
+       }
+}
+
+/*
+ * Create event_notifiers associated with a event_notifier enabler (if not already present).
+ */
+static
+int lttng_event_notifier_enabler_ref_event_notifiers(
+               struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+       struct lttng_event_notifier_group *event_notifier_group = event_notifier_enabler->group;
+       struct lttng_enabler *base_enabler = lttng_event_notifier_enabler_as_enabler(event_notifier_enabler);
+       struct lttng_event_notifier *event_notifier;
+
+       if (base_enabler->event_param.instrumentation == LTTNG_KERNEL_SYSCALL &&
+                       base_enabler->event_param.u.syscall.abi == LTTNG_KERNEL_SYSCALL_ABI_ALL &&
+                       base_enabler->event_param.u.syscall.match == LTTNG_KERNEL_SYSCALL_MATCH_NAME &&
+                       !strcmp(base_enabler->event_param.name, "*")) {
+
+               int enabled = base_enabler->enabled;
+               enum lttng_kernel_syscall_entryexit entryexit = base_enabler->event_param.u.syscall.entryexit;
+
+               if (entryexit == LTTNG_KERNEL_SYSCALL_ENTRY || entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT)
+                       WRITE_ONCE(event_notifier_group->syscall_all_entry, enabled);
+
+               if (entryexit == LTTNG_KERNEL_SYSCALL_EXIT || entryexit == LTTNG_KERNEL_SYSCALL_ENTRYEXIT)
+                       WRITE_ONCE(event_notifier_group->syscall_all_exit, enabled);
+
+       }
+
+       /* First ensure that probe event_notifiers are created for this enabler. */
+       lttng_create_event_notifier_if_missing(event_notifier_enabler);
+
+       /* Link the created event_notifier with its associated enabler. */
+       list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, list) {
+               struct lttng_enabler_ref *enabler_ref;
+
+               if (!lttng_event_notifier_enabler_match_event_notifier(event_notifier_enabler, event_notifier))
+                       continue;
+
+               enabler_ref = lttng_enabler_ref(&event_notifier->enablers_ref_head,
+                       lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
+               if (!enabler_ref) {
+                       /*
+                        * If no backward ref, create it.
+                        * Add backward ref from event_notifier to enabler.
+                        */
+                       enabler_ref = kzalloc(sizeof(*enabler_ref), GFP_KERNEL);
+                       if (!enabler_ref)
+                               return -ENOMEM;
+
+                       enabler_ref->ref = lttng_event_notifier_enabler_as_enabler(
+                               event_notifier_enabler);
+                       list_add(&enabler_ref->node,
+                               &event_notifier->enablers_ref_head);
+               }
+
+               /*
+                * Link filter bytecodes if not linked yet.
+                */
+               lttng_enabler_link_bytecode(event_notifier->desc,
+                       lttng_static_ctx, &event_notifier->filter_bytecode_runtime_head,
+                       &lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->filter_bytecode_head);
+
+               /* Link capture bytecodes if not linked yet. */
+               lttng_enabler_link_bytecode(event_notifier->desc,
+                       lttng_static_ctx, &event_notifier->capture_bytecode_runtime_head,
+                       &event_notifier_enabler->capture_bytecode_head);
+
+               event_notifier->num_captures = event_notifier_enabler->num_captures;
+       }
+       return 0;
+}
+
 /*
  * Called at module load: connect the probe on all enablers matching
  * this event.
@@ -1574,6 +2271,39 @@ int lttng_fix_pending_events(void)
        return 0;
 }
 
+static bool lttng_event_notifier_group_has_active_event_notifiers(
+               struct lttng_event_notifier_group *event_notifier_group)
+{
+       struct lttng_event_notifier_enabler *event_notifier_enabler;
+
+       list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head,
+                       node) {
+               if (event_notifier_enabler->base.enabled)
+                       return true;
+       }
+       return false;
+}
+
+bool lttng_event_notifier_active(void)
+{
+       struct lttng_event_notifier_group *event_notifier_group;
+
+       list_for_each_entry(event_notifier_group, &event_notifier_groups, node) {
+               if (lttng_event_notifier_group_has_active_event_notifiers(event_notifier_group))
+                       return true;
+       }
+       return false;
+}
+
+int lttng_fix_pending_event_notifiers(void)
+{
+       struct lttng_event_notifier_group *event_notifier_group;
+
+       list_for_each_entry(event_notifier_group, &event_notifier_groups, node)
+               lttng_event_notifier_group_sync_enablers(event_notifier_group);
+       return 0;
+}
+
 struct lttng_event_enabler *lttng_event_enabler_create(
                enum lttng_enabler_format_type format_type,
                struct lttng_kernel_event *event_param,
@@ -1618,17 +2348,17 @@ int lttng_event_enabler_disable(struct lttng_event_enabler *event_enabler)
 }
 
 static
-int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
+int lttng_enabler_attach_filter_bytecode(struct lttng_enabler *enabler,
                struct lttng_kernel_filter_bytecode __user *bytecode)
 {
-       struct lttng_filter_bytecode_node *bytecode_node;
+       struct lttng_bytecode_node *bytecode_node;
        uint32_t bytecode_len;
        int ret;
 
        ret = get_user(bytecode_len, &bytecode->len);
        if (ret)
                return ret;
-       bytecode_node = kzalloc(sizeof(*bytecode_node) + bytecode_len,
+       bytecode_node = lttng_kvzalloc(sizeof(*bytecode_node) + bytecode_len,
                        GFP_KERNEL);
        if (!bytecode_node)
                return -ENOMEM;
@@ -1637,6 +2367,7 @@ int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
        if (ret)
                goto error_free;
 
+       bytecode_node->type = LTTNG_BYTECODE_NODE_TYPE_FILTER;
        bytecode_node->enabler = enabler;
        /* Enforce length based on allocated size */
        bytecode_node->bc.len = bytecode_len;
@@ -1645,15 +2376,15 @@ int lttng_enabler_attach_bytecode(struct lttng_enabler *enabler,
        return 0;
 
 error_free:
-       kfree(bytecode_node);
+       lttng_kvfree(bytecode_node);
        return ret;
 }
 
-int lttng_event_enabler_attach_bytecode(struct lttng_event_enabler *event_enabler,
+int lttng_event_enabler_attach_filter_bytecode(struct lttng_event_enabler *event_enabler,
                struct lttng_kernel_filter_bytecode __user *bytecode)
 {
        int ret;
-       ret = lttng_enabler_attach_bytecode(
+       ret = lttng_enabler_attach_filter_bytecode(
                lttng_event_enabler_as_enabler(event_enabler), bytecode);
        if (ret)
                goto error;
@@ -1671,7 +2402,7 @@ int lttng_event_add_callsite(struct lttng_event *event,
 
        switch (event->instrumentation) {
        case LTTNG_KERNEL_UPROBE:
-               return lttng_uprobes_add_callsite(event, callsite);
+               return lttng_uprobes_event_add_callsite(event, callsite);
        default:
                return -EINVAL;
        }
@@ -1686,12 +2417,12 @@ int lttng_event_enabler_attach_context(struct lttng_event_enabler *event_enabler
 static
 void lttng_enabler_destroy(struct lttng_enabler *enabler)
 {
-       struct lttng_filter_bytecode_node *filter_node, *tmp_filter_node;
+       struct lttng_bytecode_node *filter_node, *tmp_filter_node;
 
        /* Destroy filter bytecode */
        list_for_each_entry_safe(filter_node, tmp_filter_node,
                        &enabler->filter_bytecode_head, node) {
-               kfree(filter_node);
+               lttng_kvfree(filter_node);
        }
 }
 
@@ -1707,6 +2438,156 @@ void lttng_event_enabler_destroy(struct lttng_event_enabler *event_enabler)
        kfree(event_enabler);
 }
 
+struct lttng_event_notifier_enabler *lttng_event_notifier_enabler_create(
+               struct lttng_event_notifier_group *event_notifier_group,
+               enum lttng_enabler_format_type format_type,
+               struct lttng_kernel_event_notifier *event_notifier_param)
+{
+       struct lttng_event_notifier_enabler *event_notifier_enabler;
+
+       event_notifier_enabler = kzalloc(sizeof(*event_notifier_enabler), GFP_KERNEL);
+       if (!event_notifier_enabler)
+               return NULL;
+
+       event_notifier_enabler->base.format_type = format_type;
+       INIT_LIST_HEAD(&event_notifier_enabler->base.filter_bytecode_head);
+       INIT_LIST_HEAD(&event_notifier_enabler->capture_bytecode_head);
+
+       event_notifier_enabler->error_counter_index = event_notifier_param->error_counter_index;
+       event_notifier_enabler->num_captures = 0;
+
+       memcpy(&event_notifier_enabler->base.event_param, &event_notifier_param->event,
+               sizeof(event_notifier_enabler->base.event_param));
+       event_notifier_enabler->base.evtype = LTTNG_TYPE_ENABLER;
+
+       event_notifier_enabler->base.enabled = 0;
+       event_notifier_enabler->base.user_token = event_notifier_param->event.token;
+       event_notifier_enabler->group = event_notifier_group;
+
+       mutex_lock(&sessions_mutex);
+       list_add(&event_notifier_enabler->node, &event_notifier_enabler->group->enablers_head);
+       lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+
+       mutex_unlock(&sessions_mutex);
+
+       return event_notifier_enabler;
+}
+
+int lttng_event_notifier_enabler_enable(
+               struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+       mutex_lock(&sessions_mutex);
+       lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 1;
+       lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+       mutex_unlock(&sessions_mutex);
+       return 0;
+}
+
+int lttng_event_notifier_enabler_disable(
+               struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+       mutex_lock(&sessions_mutex);
+       lttng_event_notifier_enabler_as_enabler(event_notifier_enabler)->enabled = 0;
+       lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+       mutex_unlock(&sessions_mutex);
+       return 0;
+}
+
+int lttng_event_notifier_enabler_attach_filter_bytecode(
+               struct lttng_event_notifier_enabler *event_notifier_enabler,
+               struct lttng_kernel_filter_bytecode __user *bytecode)
+{
+       int ret;
+
+       ret = lttng_enabler_attach_filter_bytecode(
+               lttng_event_notifier_enabler_as_enabler(event_notifier_enabler),
+               bytecode);
+       if (ret)
+               goto error;
+
+       lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+       return 0;
+
+error:
+       return ret;
+}
+
+int lttng_event_notifier_enabler_attach_capture_bytecode(
+               struct lttng_event_notifier_enabler *event_notifier_enabler,
+               struct lttng_kernel_capture_bytecode __user *bytecode)
+{
+       struct lttng_bytecode_node *bytecode_node;
+       struct lttng_enabler *enabler =
+                       lttng_event_notifier_enabler_as_enabler(event_notifier_enabler);
+       uint32_t bytecode_len;
+       int ret;
+
+       ret = get_user(bytecode_len, &bytecode->len);
+       if (ret)
+               return ret;
+
+       bytecode_node = lttng_kvzalloc(sizeof(*bytecode_node) + bytecode_len,
+                       GFP_KERNEL);
+       if (!bytecode_node)
+               return -ENOMEM;
+
+       ret = copy_from_user(&bytecode_node->bc, bytecode,
+               sizeof(*bytecode) + bytecode_len);
+       if (ret)
+               goto error_free;
+
+       bytecode_node->type = LTTNG_BYTECODE_NODE_TYPE_CAPTURE;
+       bytecode_node->enabler = enabler;
+
+       /* Enforce length based on allocated size */
+       bytecode_node->bc.len = bytecode_len;
+       list_add_tail(&bytecode_node->node, &event_notifier_enabler->capture_bytecode_head);
+
+       event_notifier_enabler->num_captures++;
+
+       lttng_event_notifier_group_sync_enablers(event_notifier_enabler->group);
+       goto end;
+
+error_free:
+       lttng_kvfree(bytecode_node);
+end:
+       return ret;
+}
+
+int lttng_event_notifier_add_callsite(struct lttng_event_notifier *event_notifier,
+               struct lttng_kernel_event_callsite __user *callsite)
+{
+
+       switch (event_notifier->instrumentation) {
+       case LTTNG_KERNEL_UPROBE:
+               return lttng_uprobes_event_notifier_add_callsite(event_notifier,
+                               callsite);
+       default:
+               return -EINVAL;
+       }
+}
+
+int lttng_event_notifier_enabler_attach_context(
+               struct lttng_event_notifier_enabler *event_notifier_enabler,
+               struct lttng_kernel_context *context_param)
+{
+       return -ENOSYS;
+}
+
+static
+void lttng_event_notifier_enabler_destroy(
+               struct lttng_event_notifier_enabler *event_notifier_enabler)
+{
+       if (!event_notifier_enabler) {
+               return;
+       }
+
+       list_del(&event_notifier_enabler->node);
+
+       lttng_enabler_destroy(lttng_event_notifier_enabler_as_enabler(event_notifier_enabler));
+       kfree(event_notifier_enabler);
+}
+
 /*
  * lttng_session_sync_event_enablers should be called just before starting a
  * session.
@@ -1778,8 +2659,8 @@ void lttng_session_sync_event_enablers(struct lttng_session *session)
 
                /* Enable filters */
                list_for_each_entry(runtime,
-                               &event->bytecode_runtime_head, node)
-                       lttng_filter_sync_state(runtime);
+                               &event->filter_bytecode_runtime_head, node)
+                       lttng_bytecode_filter_sync_state(runtime);
        }
 }
 
@@ -1799,6 +2680,78 @@ void lttng_session_lazy_sync_event_enablers(struct lttng_session *session)
        lttng_session_sync_event_enablers(session);
 }
 
+static
+void lttng_event_notifier_group_sync_enablers(struct lttng_event_notifier_group *event_notifier_group)
+{
+       struct lttng_event_notifier_enabler *event_notifier_enabler;
+       struct lttng_event_notifier *event_notifier;
+
+       list_for_each_entry(event_notifier_enabler, &event_notifier_group->enablers_head, node)
+               lttng_event_notifier_enabler_ref_event_notifiers(event_notifier_enabler);
+
+       /*
+        * For each event_notifier, if at least one of its enablers is enabled,
+        * we enable the event_notifier, else we disable it.
+        */
+       list_for_each_entry(event_notifier, &event_notifier_group->event_notifiers_head, list) {
+               struct lttng_enabler_ref *enabler_ref;
+               struct lttng_bytecode_runtime *runtime;
+               int enabled = 0, has_enablers_without_bytecode = 0;
+
+               switch (event_notifier->instrumentation) {
+               case LTTNG_KERNEL_TRACEPOINT:
+               case LTTNG_KERNEL_SYSCALL:
+                       /* Enable event_notifiers */
+                       list_for_each_entry(enabler_ref,
+                                       &event_notifier->enablers_ref_head, node) {
+                               if (enabler_ref->ref->enabled) {
+                                       enabled = 1;
+                                       break;
+                               }
+                       }
+                       break;
+               default:
+                       /* Not handled with sync. */
+                       continue;
+               }
+
+               WRITE_ONCE(event_notifier->enabled, enabled);
+               /*
+                * Sync tracepoint registration with event_notifier enabled
+                * state.
+                */
+               if (enabled) {
+                       if (!event_notifier->registered)
+                               register_event_notifier(event_notifier);
+               } else {
+                       if (event_notifier->registered)
+                               _lttng_event_notifier_unregister(event_notifier);
+               }
+
+               /* Check if has enablers without bytecode enabled */
+               list_for_each_entry(enabler_ref,
+                               &event_notifier->enablers_ref_head, node) {
+                       if (enabler_ref->ref->enabled
+                                       && list_empty(&enabler_ref->ref->filter_bytecode_head)) {
+                               has_enablers_without_bytecode = 1;
+                               break;
+                       }
+               }
+               event_notifier->has_enablers_without_bytecode =
+                       has_enablers_without_bytecode;
+
+               /* Enable filters */
+               list_for_each_entry(runtime,
+                               &event_notifier->filter_bytecode_runtime_head, node)
+                       lttng_bytecode_filter_sync_state(runtime);
+
+               /* Enable captures */
+               list_for_each_entry(runtime,
+                               &event_notifier->capture_bytecode_runtime_head, node)
+                       lttng_bytecode_capture_sync_state(runtime);
+       }
+}
+
 /*
  * Serialize at most one packet worth of metadata into a metadata
  * channel.
@@ -3050,6 +4003,29 @@ void lttng_transport_unregister(struct lttng_transport *transport)
 }
 EXPORT_SYMBOL_GPL(lttng_transport_unregister);
 
+void lttng_counter_transport_register(struct lttng_counter_transport *transport)
+{
+       /*
+        * Make sure no page fault can be triggered by the module about to be
+        * registered. We deal with this here so we don't have to call
+        * vmalloc_sync_mappings() in each module's init.
+        */
+       wrapper_vmalloc_sync_mappings();
+
+       mutex_lock(&sessions_mutex);
+       list_add_tail(&transport->node, &lttng_counter_transport_list);
+       mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(lttng_counter_transport_register);
+
+void lttng_counter_transport_unregister(struct lttng_counter_transport *transport)
+{
+       mutex_lock(&sessions_mutex);
+       list_del(&transport->node);
+       mutex_unlock(&sessions_mutex);
+}
+EXPORT_SYMBOL_GPL(lttng_counter_transport_unregister);
+
 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
 
 enum cpuhp_state lttng_hp_prepare;
@@ -3202,7 +4178,12 @@ static int __init lttng_events_init(void)
        event_cache = KMEM_CACHE(lttng_event, 0);
        if (!event_cache) {
                ret = -ENOMEM;
-               goto error_kmem;
+               goto error_kmem_event;
+       }
+       event_notifier_cache = KMEM_CACHE(lttng_event_notifier, 0);
+       if (!event_notifier_cache) {
+               ret = -ENOMEM;
+               goto error_kmem_event_notifier;
        }
        ret = lttng_abi_init();
        if (ret)
@@ -3236,8 +4217,10 @@ error_hotplug:
 error_logger:
        lttng_abi_exit();
 error_abi:
+       kmem_cache_destroy(event_notifier_cache);
+error_kmem_event_notifier:
        kmem_cache_destroy(event_cache);
-error_kmem:
+error_kmem_event:
        lttng_tracepoint_exit();
 error_tp:
        lttng_context_exit();
@@ -3272,6 +4255,7 @@ static void __exit lttng_events_exit(void)
        list_for_each_entry_safe(session, tmpsession, &sessions, list)
                lttng_session_destroy(session);
        kmem_cache_destroy(event_cache);
+       kmem_cache_destroy(event_notifier_cache);
        lttng_tracepoint_exit();
        lttng_context_exit();
        printk(KERN_NOTICE "LTTng: Unloaded modules v%s.%s.%s%s (%s)%s%s\n",
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