X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fkernel.c;h=27b72a5afa133ae651b9e294a68871e50c5ee8ef;hp=d7c7984d201ba96c82d050eb71a48dca798c8e38;hb=refs%2Fheads%2Fsow-2020-0002-rev1;hpb=3a4595c2469472dee1656cde5f8882c2123efd3c

diff --git a/src/bin/lttng-sessiond/kernel.c b/src/bin/lttng-sessiond/kernel.c
index d7c7984d2..27b72a5af 100644
--- a/src/bin/lttng-sessiond/kernel.c
+++ b/src/bin/lttng-sessiond/kernel.c
@@ -15,6 +15,7 @@
 #include <sys/types.h>
 
 #include <common/common.h>
+#include <common/hashtable/utils.h>
 #include <common/trace-chunk.h>
 #include <common/kernel-ctl/kernel-ctl.h>
 #include <common/kernel-ctl/kernel-ioctl.h>
@@ -25,16 +26,28 @@
 #include <lttng/lttng-error.h>
 #include <lttng/tracker.h>
 
+#include <lttng/userspace-probe.h>
+#include <lttng/userspace-probe-internal.h>
+#include <lttng/condition/event-rule.h>
+#include <lttng/condition/event-rule-internal.h>
+#include <lttng/event-rule/event-rule.h>
+#include <lttng/event-rule/event-rule-internal.h>
+#include <lttng/event-rule/uprobe-internal.h>
+
 #include "lttng-sessiond.h"
 #include "lttng-syscall.h"
+#include "condition-internal.h"
 #include "consumer.h"
 #include "kernel.h"
 #include "kernel-consumer.h"
 #include "kern-modules.h"
+#include "sessiond-config.h"
 #include "utils.h"
 #include "rotate.h"
 #include "modprobe.h"
 #include "tracker.h"
+#include "trigger-error-accounting.h"
+#include "notification-thread-commands.h"
 
 /*
  * Key used to reference a channel between the sessiond and the consumer. This
@@ -45,9 +58,10 @@ static uint64_t next_kernel_channel_key;
 static const char *module_proc_lttng = "/proc/lttng";
 
 static int kernel_tracer_fd = -1;
+static int kernel_tracer_trigger_group_fd = -1;
+static int kernel_tracer_trigger_group_notification_fd = -1;
+static struct cds_lfht *kernel_tracer_token_ht;
 
-#include <lttng/userspace-probe.h>
-#include <lttng/userspace-probe-internal.h>
 /*
  * Add context on a kernel channel.
  *
@@ -219,6 +233,44 @@ error:
 	return -1;
 }
 
+/*
+ * Create a kernel channel, register it to the kernel tracer and add it to the
+ * kernel session.
+ */
+static
+int kernel_create_trigger_group(int *trigger_group_fd)
+{
+	int ret;
+	int local_fd = -1;
+
+	assert(trigger_group_fd);
+
+	/* Kernel tracer channel creation */
+	ret = kernctl_create_trigger_group(kernel_tracer_fd);
+	if (ret < 0) {
+		PERROR("ioctl kernel create trigger group");
+		ret = -1;
+		goto error;
+	}
+
+	/* Store locally */
+	local_fd = ret;
+
+	/* Prevent fd duplication after execlp() */
+	ret = fcntl(local_fd, F_SETFD, FD_CLOEXEC);
+	if (ret < 0) {
+		PERROR("fcntl session fd");
+	}
+
+	DBG("Kernel trigger group created (fd: %d)",
+			local_fd);
+	ret = 0;
+
+error:
+	*trigger_group_fd = local_fd;
+	return ret;
+}
+
 /*
  * Compute the offset of the instrumentation byte in the binary based on the
  * function probe location using the ELF lookup method.
@@ -230,7 +282,7 @@ error:
 static
 int extract_userspace_probe_offset_function_elf(
 		const struct lttng_userspace_probe_location *probe_location,
-		struct ltt_kernel_session *session, uint64_t *offset)
+		uid_t uid, gid_t gid, uint64_t *offset)
 {
 	int fd;
 	int ret = 0;
@@ -267,8 +319,7 @@ int extract_userspace_probe_offset_function_elf(
 		goto end;
 	}
 
-	ret = run_as_extract_elf_symbol_offset(fd, symbol, session->uid,
-			session->gid, offset);
+	ret = run_as_extract_elf_symbol_offset(fd, symbol, uid, gid, offset);
 	if (ret < 0) {
 		DBG("userspace probe offset calculation failed for "
 				"function %s", symbol);
@@ -292,7 +343,7 @@ end:
 static
 int extract_userspace_probe_offset_tracepoint_sdt(
 		const struct lttng_userspace_probe_location *probe_location,
-		struct ltt_kernel_session *session, uint64_t **offsets,
+		uid_t uid, gid_t gid, uint64_t **offsets,
 		uint32_t *offsets_count)
 {
 	enum lttng_userspace_probe_location_lookup_method_type lookup_method_type;
@@ -338,7 +389,7 @@ int extract_userspace_probe_offset_tracepoint_sdt(
 	}
 
 	ret = run_as_extract_sdt_probe_offsets(fd, provider_name, probe_name,
-			session->uid, session->gid, offsets, offsets_count);
+			uid, gid, offsets, offsets_count);
 	if (ret < 0) {
 		DBG("userspace probe offset calculation failed for sdt "
 				"probe %s:%s", provider_name, probe_name);
@@ -359,29 +410,16 @@ end:
 	return ret;
 }
 
-/*
- * Extract the offsets of the instrumentation point for the different lookup
- * methods.
- */
 static
-int userspace_probe_add_callsites(struct lttng_event *ev,
-			struct ltt_kernel_session *session, int fd)
+int userspace_probe_add_callsite(
+		const struct lttng_userspace_probe_location *location,
+		uid_t uid, gid_t gid, int fd)
 {
 	const struct lttng_userspace_probe_location_lookup_method *lookup_method = NULL;
 	enum lttng_userspace_probe_location_lookup_method_type type;
-	const struct lttng_userspace_probe_location *location = NULL;
 	int ret;
 
-	assert(ev);
-	assert(ev->type == LTTNG_EVENT_USERSPACE_PROBE);
-
-	location = lttng_event_get_userspace_probe_location(ev);
-	if (!location) {
-		ret = -1;
-		goto end;
-	}
-	lookup_method =
-			lttng_userspace_probe_location_get_lookup_method(location);
+	lookup_method = lttng_userspace_probe_location_get_lookup_method(location);
 	if (!lookup_method) {
 		ret = -1;
 		goto end;
@@ -394,7 +432,8 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
 		struct lttng_kernel_event_callsite callsite;
 		uint64_t offset;
 
-		ret = extract_userspace_probe_offset_function_elf(location, session, &offset);
+		ret = extract_userspace_probe_offset_function_elf(location,
+				uid, gid, &offset);
 		if (ret) {
 			ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
 			goto end;
@@ -403,8 +442,7 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
 		callsite.u.uprobe.offset = offset;
 		ret = kernctl_add_callsite(fd, &callsite);
 		if (ret) {
-			WARN("Adding callsite to userspace probe "
-					"event %s failed.", ev->name);
+			WARN("Adding callsite to ELF userspace probe failed.");
 			ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 			goto end;
 		}
@@ -421,8 +459,8 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
 		 * This call allocates the offsets buffer. This buffer must be freed
 		 * by the caller
 		 */
-		ret = extract_userspace_probe_offset_tracepoint_sdt(location, session,
-				&offsets, &offsets_count);
+		ret = extract_userspace_probe_offset_tracepoint_sdt(location,
+				uid, gid, &offsets, &offsets_count);
 		if (ret) {
 			ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
 			goto end;
@@ -431,8 +469,8 @@ int userspace_probe_add_callsites(struct lttng_event *ev,
 			callsite.u.uprobe.offset = offsets[i];
 			ret = kernctl_add_callsite(fd, &callsite);
 			if (ret) {
-				WARN("Adding callsite to userspace probe "
-						"event %s failed.", ev->name);
+				WARN("Adding callsite to SDT userspace probe "
+					"failed.");
 				ret = LTTNG_ERR_KERN_ENABLE_FAIL;
 				free(offsets);
 				goto end;
@@ -449,6 +487,71 @@ end:
 	return ret;
 }
 
+/*
+ * Extract the offsets of the instrumentation point for the different lookup
+ * methods.
+ */
+static
+int userspace_probe_event_add_callsites(struct lttng_event *ev,
+			struct ltt_kernel_session *session, int fd)
+{
+	const struct lttng_userspace_probe_location *location = NULL;
+	int ret;
+
+	assert(ev);
+	assert(ev->type == LTTNG_EVENT_USERSPACE_PROBE);
+
+	location = lttng_event_get_userspace_probe_location(ev);
+	if (!location) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = userspace_probe_add_callsite(location, session->uid, session->gid,
+		fd);
+	if (ret) {
+		WARN("Adding callsite to userspace probe event \"%s\" "
+			"failed.", ev->name);
+	}
+
+end:
+	return ret;
+}
+
+/*
+ * Extract the offsets of the instrumentation point for the different lookup
+ * methods.
+ */
+static int userspace_probe_event_rule_add_callsites(
+		const struct lttng_event_rule *rule,
+		const struct lttng_credentials *creds,
+		int fd)
+{
+	const struct lttng_userspace_probe_location *location = NULL;
+	enum lttng_event_rule_status status;
+	int ret;
+
+	assert(rule);
+	assert(creds);
+	assert(lttng_event_rule_get_type(rule) == LTTNG_EVENT_RULE_TYPE_UPROBE);
+
+	status = lttng_event_rule_uprobe_get_location(rule, &location);
+	if (status != LTTNG_EVENT_RULE_STATUS_OK || !location) {
+		ret = -1;
+		goto end;
+	}
+
+	ret = userspace_probe_add_callsite(
+			location, lttng_credentials_get_uid(creds), lttng_credentials_get_gid(creds), fd);
+	if (ret) {
+		WARN("Adding callsite to userspace probe object %d"
+			"failed.", fd);
+	}
+
+end:
+	return ret;
+}
+
 /*
  * Create a kernel event, enable it to the kernel tracer and add it to the
  * channel event list of the kernel session.
@@ -457,7 +560,7 @@ end:
 int kernel_create_event(struct lttng_event *ev,
 		struct ltt_kernel_channel *channel,
 		char *filter_expression,
-		struct lttng_filter_bytecode *filter)
+		struct lttng_bytecode *filter)
 {
 	int err, fd;
 	enum lttng_error_code ret;
@@ -518,7 +621,8 @@ int kernel_create_event(struct lttng_event *ev,
 	}
 
 	if (ev->type == LTTNG_EVENT_USERSPACE_PROBE) {
-		ret = userspace_probe_add_callsites(ev, channel->session, event->fd);
+		ret = userspace_probe_event_add_callsites(ev, channel->session,
+			event->fd);
 		if (ret) {
 			goto add_callsite_error;
 		}
@@ -675,6 +779,42 @@ error:
 	return ret;
 }
 
+/*
+ * Disable a kernel trigger.
+ */
+static
+int kernel_disable_token_event_rule(struct ltt_kernel_token_event_rule *event)
+{
+	int ret;
+
+	assert(event);
+
+	rcu_read_lock();
+	cds_lfht_del(kernel_tracer_token_ht, &event->ht_node);
+	rcu_read_unlock();
+
+	ret = kernctl_disable(event->fd);
+	if (ret < 0) {
+		switch (-ret) {
+		case EEXIST:
+			ret = LTTNG_ERR_KERN_EVENT_EXIST;
+			break;
+		default:
+			PERROR("disable kernel event");
+			break;
+		}
+		goto error;
+	}
+
+	event->enabled = 0;
+	DBG("Kernel trigger token %" PRIu64" disabled (fd: %d)", event->token, event->fd);
+
+	return 0;
+
+error:
+	return ret;
+}
+
 static
 struct process_attr_tracker *_kernel_get_process_attr_tracker(
 		struct ltt_kernel_session *session,
@@ -1796,6 +1936,7 @@ LTTNG_HIDDEN
 int init_kernel_tracer(void)
 {
 	int ret;
+	enum lttng_error_code error_code_ret;
 	bool is_root = !getuid();
 
 	/* Modprobe lttng kernel modules */
@@ -1827,20 +1968,48 @@ int init_kernel_tracer(void)
 	if (ret < 0) {
 		goto error_modules;
 	}
-
 	if (ret < 1) {
 		WARN("Kernel tracer does not support buffer monitoring. "
 			"The monitoring timer of channels in the kernel domain "
 			"will be set to 0 (disabled).");
 	}
 
+	ret = kernel_create_trigger_group(&kernel_tracer_trigger_group_fd);
+	if (ret < 0) {
+		/* TODO: error handling if it is not supported etc. */
+		WARN("Failed trigger group creation");
+		kernel_tracer_trigger_group_fd = -1;
+		/* This is not fatal */
+	} else {
+
+		error_code_ret = kernel_create_trigger_group_notification_fd(
+				&kernel_tracer_trigger_group_notification_fd);
+		if (error_code_ret != LTTNG_OK) {
+			goto error_modules;
+		}
+
+		trigger_error_accounting_register_kernel(kernel_tracer_trigger_group_fd);
+		if (ret < 0) {
+			goto error_modules;
+		}
+	}
+
+	kernel_tracer_token_ht = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0,
+		CDS_LFHT_AUTO_RESIZE|CDS_LFHT_ACCOUNTING, NULL);
+	if (!kernel_tracer_token_ht) {
+		goto error_modules;
+	}
+
 	DBG("Kernel tracer fd %d", kernel_tracer_fd);
+	DBG("Kernel tracer trigger group fd %d", kernel_tracer_trigger_group_fd);
+	DBG("Kernel tracer trigger group notification fd %d", kernel_tracer_trigger_group_notification_fd);
 
 	ret = syscall_init_table(kernel_tracer_fd);
 	if (ret < 0) {
 		ERR("Unable to populate syscall table. Syscall tracing won't "
 			"work for this session daemon.");
 	}
+
 	return 0;
 
 error_version:
@@ -1875,6 +2044,40 @@ LTTNG_HIDDEN
 void cleanup_kernel_tracer(void)
 {
 	int ret;
+	struct cds_lfht_iter iter;
+
+	struct ltt_kernel_token_event_rule *rule = NULL;
+        cds_lfht_for_each_entry(kernel_tracer_token_ht, &iter, rule, ht_node) {
+		kernel_disable_token_event_rule(rule);
+		trace_kernel_destroy_token_event_rule(rule);
+		cds_lfht_del(kernel_tracer_token_ht, &rule->ht_node);
+	}
+
+	DBG2("Closing kernel trigger group notification fd");
+	if (kernel_tracer_trigger_group_notification_fd >= 0) {
+		
+		ret = notification_thread_command_remove_application(
+				notification_thread_handle,
+				kernel_tracer_trigger_group_notification_fd);
+		if (ret != LTTNG_OK) {
+			ERR("Failed to remove kernel trigger notification from notification thread");
+		}
+		ret = close(kernel_tracer_trigger_group_notification_fd);
+		if (ret) {
+			PERROR("close");
+		}
+		kernel_tracer_trigger_group_notification_fd = -1;
+	}
+
+	/* TODO: do we iterate over the list to remove all token? */
+	DBG2("Closing kernel trigger group fd");
+	if (kernel_tracer_trigger_group_fd >= 0) {
+		ret = close(kernel_tracer_trigger_group_fd);
+		if (ret) {
+			PERROR("close");
+		}
+		kernel_tracer_trigger_group_fd = -1;
+	}
 
 	DBG2("Closing kernel fd");
 	if (kernel_tracer_fd >= 0) {
@@ -1884,6 +2087,7 @@ void cleanup_kernel_tracer(void)
 		}
 		kernel_tracer_fd = -1;
 	}
+
 	DBG("Unloading kernel modules");
 	modprobe_remove_lttng_all();
 	free(syscall_table);
@@ -1974,3 +2178,322 @@ end:
 	rcu_read_unlock();
 	return status;
 }
+
+enum lttng_error_code kernel_create_trigger_group_notification_fd(
+		int *trigger_group_notification_fd)
+{
+	enum lttng_error_code error_code_ret;
+	int local_fd = -1, ret;
+
+	assert(trigger_group_notification_fd);
+
+	ret = kernctl_create_trigger_group_notification_fd(kernel_tracer_trigger_group_fd);
+	if (ret < 0) {
+		PERROR("ioctl kernel create trigger group");
+		error_code_ret = LTTNG_ERR_TRIGGER_GROUP_NOTIFICATION_FD;
+		goto error;
+	}
+
+	/* Store locally */
+	local_fd = ret;
+
+	/* Prevent fd duplication after execlp() */
+	ret = fcntl(local_fd, F_SETFD, FD_CLOEXEC);
+	if (ret < 0) {
+		PERROR("fcntl session fd");
+		error_code_ret = LTTNG_ERR_TRIGGER_GROUP_NOTIFICATION_FD;
+		goto error;
+	}
+
+	DBG("Kernel trigger group notification created (fd: %d)",
+			local_fd);
+	error_code_ret = LTTNG_OK;
+	*trigger_group_notification_fd = local_fd;
+
+error:
+	return error_code_ret;
+}
+
+enum lttng_error_code kernel_create_trigger_group_error_counter(
+		int *error_counter_fd, size_t nb_bucket)
+{
+	enum lttng_error_code error_code_ret;
+	int local_fd = -1, ret;
+	struct lttng_kernel_counter_conf error_counter_conf;
+
+	assert(error_counter_fd);
+
+	error_counter_conf.arithmetic = LTTNG_KERNEL_COUNTER_ARITHMETIC_MODULAR;
+	error_counter_conf.bitness = LTTNG_KERNEL_COUNTER_BITNESS_64BITS;
+	error_counter_conf.global_sum_step = 0;
+	error_counter_conf.number_dimensions = 1;
+	error_counter_conf.dimensions[0].size = nb_bucket;
+	error_counter_conf.dimensions[0].has_underflow = false;
+	error_counter_conf.dimensions[0].has_overflow = false;
+
+	ret = kernctl_create_trigger_group_error_counter(
+			kernel_tracer_trigger_group_fd, &error_counter_conf);
+	if (ret < 0) {
+		PERROR("ioctl kernel create trigger group error counter");
+		error_code_ret = LTTNG_ERR_TRIGGER_GROUP_ERROR_COUNTER;
+		goto error;
+	}
+
+	/* Store locally */
+	local_fd = ret;
+
+	/* Prevent fd duplication after execlp() */
+	ret = fcntl(local_fd, F_SETFD, FD_CLOEXEC);
+	if (ret < 0) {
+		error_code_ret = LTTNG_ERR_TRIGGER_GROUP_ERROR_COUNTER;
+		PERROR("fcntl session fd");
+	}
+
+	DBG("Kernel trigger group error counter (fd: %d)",
+			local_fd);
+	error_code_ret = LTTNG_OK;
+
+error:
+	*error_counter_fd = local_fd;
+	return error_code_ret;
+}
+
+enum lttng_error_code kernel_destroy_trigger_group_notification_fd(
+		int trigger_group_notification_fd)
+{
+	enum lttng_error_code ret = LTTNG_OK;
+	DBG("Closing trigger group notification fd %d", trigger_group_notification_fd);
+	if (trigger_group_notification_fd >= 0) {
+		ret = close(trigger_group_notification_fd);
+		if (ret) {
+			PERROR("close");
+		}
+	}
+	return ret;
+}
+
+static
+unsigned long hash_trigger(struct lttng_trigger *trigger)
+{
+	const struct lttng_condition *condition =
+			lttng_trigger_get_const_condition(trigger);
+	return lttng_condition_hash(condition);
+}
+
+static
+int match_trigger(struct cds_lfht_node *node, const void *key)
+{
+	struct ltt_kernel_token_event_rule *token;
+	const struct lttng_trigger *trigger = key;
+
+	token = caa_container_of(node, struct ltt_kernel_token_event_rule, ht_node);
+
+	return lttng_trigger_is_equal(trigger, token->trigger);
+}
+
+static enum lttng_error_code kernel_create_token_event_rule(struct lttng_trigger *trigger,
+		const struct lttng_credentials *creds, uint64_t token)
+{
+	int err, fd, ret = 0;
+	enum lttng_error_code error_code_ret;
+	struct ltt_kernel_token_event_rule *event;
+	struct lttng_kernel_trigger kernel_trigger = {};
+	unsigned int capture_bytecode_count = 0;
+	struct lttng_condition *condition = NULL;
+	struct lttng_event_rule *event_rule = NULL;
+
+	assert(trigger);
+
+	condition = lttng_trigger_get_condition(trigger);
+	assert(condition);
+	assert(lttng_condition_get_type(condition) == LTTNG_CONDITION_TYPE_EVENT_RULE_HIT);
+
+	lttng_condition_event_rule_get_rule_mutable(condition, &event_rule);
+	assert(event_rule);
+	assert(lttng_event_rule_get_type(event_rule) != LTTNG_EVENT_RULE_TYPE_UNKNOWN);
+
+	error_code_ret = trace_kernel_create_token_event_rule(trigger, token,
+			lttng_trigger_get_error_counter_index(trigger), &event);
+	if (error_code_ret != LTTNG_OK) {
+		goto error;
+	}
+
+	trace_kernel_init_trigger_from_event_rule(event_rule, &kernel_trigger);
+	kernel_trigger.id = event->token;
+	kernel_trigger.error_counter_idx = lttng_trigger_get_error_counter_index(trigger);
+
+	fd = kernctl_create_trigger(kernel_tracer_trigger_group_fd, &kernel_trigger);
+	if (fd < 0) {
+		switch (-fd) {
+		case EEXIST:
+			error_code_ret = LTTNG_ERR_KERN_EVENT_EXIST;
+			break;
+		case ENOSYS:
+			WARN("Trigger type not implemented");
+			error_code_ret = LTTNG_ERR_KERN_EVENT_ENOSYS;
+			break;
+		case ENOENT:
+			WARN("Event %s not found!", kernel_trigger.name);
+			error_code_ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+			break;
+		default:
+			error_code_ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+			PERROR("create trigger ioctl");
+		}
+		goto free_event;
+	}
+
+	event->fd = fd;
+	/* Prevent fd duplication after execlp() */
+	err = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
+	if (err < 0) {
+		PERROR("fcntl session fd");
+	}
+
+	if (event->filter) {
+		err = kernctl_filter(event->fd, event->filter);
+		if (err < 0) {
+			switch (-err) {
+			case ENOMEM:
+				error_code_ret = LTTNG_ERR_FILTER_NOMEM;
+				break;
+			default:
+				error_code_ret = LTTNG_ERR_FILTER_INVAL;
+				break;
+			}
+			goto filter_error;
+		}
+	}
+
+	if (lttng_event_rule_get_type(event_rule) ==
+			LTTNG_EVENT_RULE_TYPE_UPROBE) {
+		ret = userspace_probe_event_rule_add_callsites(
+				event_rule, creds, event->fd);
+		if (ret) {
+			error_code_ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+			goto add_callsite_error;
+		}
+	}
+
+	/* Set the capture bytecode */
+	capture_bytecode_count = lttng_trigger_get_capture_bytecode_count(trigger);
+	for (unsigned int i = 0; i < capture_bytecode_count; i++) {
+		const struct lttng_bytecode *capture_bytecode = lttng_trigger_get_capture_bytecode_at_index(trigger, i);
+		ret = kernctl_capture(event->fd, capture_bytecode);
+		if (ret < 0) {
+			error_code_ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+			goto error;
+		}
+	}
+
+	err = kernctl_enable(event->fd);
+	if (err < 0) {
+		switch (-err) {
+		case EEXIST:
+			error_code_ret = LTTNG_ERR_KERN_EVENT_EXIST;
+			break;
+		default:
+			PERROR("enable kernel trigger");
+			error_code_ret = LTTNG_ERR_KERN_ENABLE_FAIL;
+			break;
+		}
+		goto enable_error;
+	}
+
+	/* Add trigger to kernel token mapping in the hashtable. */
+	cds_lfht_add(kernel_tracer_token_ht, hash_trigger(trigger),
+			&event->ht_node);
+
+	DBG("Trigger %s created (fd: %d)", kernel_trigger.name, event->fd);
+
+	return LTTNG_OK;
+
+add_callsite_error:
+enable_error:
+filter_error:
+	{
+		int closeret;
+
+		closeret = close(event->fd);
+		if (closeret) {
+			PERROR("close event fd");
+		}
+	}
+free_event:
+	free(event);
+error:
+	return error_code_ret;
+}
+
+enum lttng_error_code kernel_register_trigger(struct lttng_trigger *trigger, const struct lttng_credentials *cmd_creds)
+{
+	enum lttng_error_code ret;
+	struct lttng_condition *condition;
+	struct lttng_event_rule *event_rule;
+	uint64_t token;
+
+	/* TODO error handling */
+
+	rcu_read_lock();
+	pthread_mutex_lock(&notification_trigger_tokens_ht_lock);
+
+	/* TODO: error checking and type checking */
+	token = lttng_trigger_get_tracer_token(trigger);
+	condition = lttng_trigger_get_condition(trigger);
+	(void) lttng_condition_event_rule_get_rule_mutable(condition, &event_rule);
+
+	assert(lttng_event_rule_get_domain_type(event_rule) == LTTNG_DOMAIN_KERNEL);
+
+	ret = kernel_create_token_event_rule(trigger, cmd_creds, token);
+	if (ret != LTTNG_OK) {
+		ERR("Failed to create kernel trigger token.");
+	}
+
+	rcu_read_unlock();
+	pthread_mutex_unlock(&notification_trigger_tokens_ht_lock);
+	return ret;
+}
+
+enum lttng_error_code kernel_unregister_trigger(struct lttng_trigger *trigger)
+{
+	struct ltt_kernel_token_event_rule *token_event_rule_element;
+	struct cds_lfht_node *node;
+	struct cds_lfht_iter iter;
+	enum lttng_error_code error_code_ret;
+	int ret;
+
+	rcu_read_lock();
+	pthread_mutex_unlock(&notification_trigger_tokens_ht_lock);
+
+	cds_lfht_lookup(kernel_tracer_token_ht, hash_trigger(trigger),
+			match_trigger, trigger, &iter);
+	node = cds_lfht_iter_get_node(&iter);
+	if (!node) {
+		error_code_ret = LTTNG_ERR_TRIGGER_NOT_FOUND;
+		goto error;
+	}
+
+	token_event_rule_element = caa_container_of(node,
+			struct ltt_kernel_token_event_rule, ht_node);
+
+	ret = kernel_disable_token_event_rule(token_event_rule_element);
+	if (ret) {
+		error_code_ret = LTTNG_ERR_FATAL;
+		goto error;
+	}
+
+	trace_kernel_destroy_token_event_rule(token_event_rule_element);
+
+	rcu_read_unlock();
+	pthread_mutex_unlock(&notification_trigger_tokens_ht_lock);
+
+	error_code_ret = LTTNG_OK;
+
+error:
+	return error_code_ret;
+}
+
+int kernel_get_notification_fd(void)
+{
+	return kernel_tracer_trigger_group_notification_fd;
+}