Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1982 insertions, 0 deletions

diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
new file mode 100644
index 000000000..918730d74
--- /dev/null
+++ b/kernel/trace/trace_events_trigger.c
@@ -0,0 +1,1982 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * trace_events_trigger - trace event triggers
+ *
+ * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
+ */
+
+#include <linux/security.h>
+#include <linux/module.h>
+#include <linux/ctype.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/rculist.h>
+
+#include "trace.h"
+
+static LIST_HEAD(trigger_commands);
+static DEFINE_MUTEX(trigger_cmd_mutex);
+
+void trigger_data_free(struct event_trigger_data *data)
+{
+	if (data->cmd_ops->set_filter)
+		data->cmd_ops->set_filter(NULL, data, NULL);
+
+	/* make sure current triggers exit before free */
+	tracepoint_synchronize_unregister();
+
+	kfree(data);
+}
+
+/**
+ * event_triggers_call - Call triggers associated with a trace event
+ * @file: The trace_event_file associated with the event
+ * @rec: The trace entry for the event, NULL for unconditional invocation
+ *
+ * For each trigger associated with an event, invoke the trigger
+ * function registered with the associated trigger command.  If rec is
+ * non-NULL, it means that the trigger requires further processing and
+ * shouldn't be unconditionally invoked.  If rec is non-NULL and the
+ * trigger has a filter associated with it, rec will checked against
+ * the filter and if the record matches the trigger will be invoked.
+ * If the trigger is a 'post_trigger', meaning it shouldn't be invoked
+ * in any case until the current event is written, the trigger
+ * function isn't invoked but the bit associated with the deferred
+ * trigger is set in the return value.
+ *
+ * Returns an enum event_trigger_type value containing a set bit for
+ * any trigger that should be deferred, ETT_NONE if nothing to defer.
+ *
+ * Called from tracepoint handlers (with rcu_read_lock_sched() held).
+ *
+ * Return: an enum event_trigger_type value containing a set bit for
+ * any trigger that should be deferred, ETT_NONE if nothing to defer.
+ */
+enum event_trigger_type
+event_triggers_call(struct trace_event_file *file,
+		    struct trace_buffer *buffer, void *rec,
+		    struct ring_buffer_event *event)
+{
+	struct event_trigger_data *data;
+	enum event_trigger_type tt = ETT_NONE;
+	struct event_filter *filter;
+
+	if (list_empty(&file->triggers))
+		return tt;
+
+	list_for_each_entry_rcu(data, &file->triggers, list) {
+		if (data->paused)
+			continue;
+		if (!rec) {
+			data->ops->trigger(data, buffer, rec, event);
+			continue;
+		}
+		filter = rcu_dereference_sched(data->filter);
+		if (filter && !filter_match_preds(filter, rec))
+			continue;
+		if (event_command_post_trigger(data->cmd_ops)) {
+			tt |= data->cmd_ops->trigger_type;
+			continue;
+		}
+		data->ops->trigger(data, buffer, rec, event);
+	}
+	return tt;
+}
+EXPORT_SYMBOL_GPL(event_triggers_call);
+
+bool __trace_trigger_soft_disabled(struct trace_event_file *file)
+{
+	unsigned long eflags = file->flags;
+
+	if (eflags & EVENT_FILE_FL_TRIGGER_MODE)
+		event_triggers_call(file, NULL, NULL, NULL);
+	if (eflags & EVENT_FILE_FL_SOFT_DISABLED)
+		return true;
+	if (eflags & EVENT_FILE_FL_PID_FILTER)
+		return trace_event_ignore_this_pid(file);
+	return false;
+}
+EXPORT_SYMBOL_GPL(__trace_trigger_soft_disabled);
+
+/**
+ * event_triggers_post_call - Call 'post_triggers' for a trace event
+ * @file: The trace_event_file associated with the event
+ * @tt: enum event_trigger_type containing a set bit for each trigger to invoke
+ *
+ * For each trigger associated with an event, invoke the trigger
+ * function registered with the associated trigger command, if the
+ * corresponding bit is set in the tt enum passed into this function.
+ * See @event_triggers_call for details on how those bits are set.
+ *
+ * Called from tracepoint handlers (with rcu_read_lock_sched() held).
+ */
+void
+event_triggers_post_call(struct trace_event_file *file,
+			 enum event_trigger_type tt)
+{
+	struct event_trigger_data *data;
+
+	list_for_each_entry_rcu(data, &file->triggers, list) {
+		if (data->paused)
+			continue;
+		if (data->cmd_ops->trigger_type & tt)
+			data->ops->trigger(data, NULL, NULL, NULL);
+	}
+}
+EXPORT_SYMBOL_GPL(event_triggers_post_call);
+
+#define SHOW_AVAILABLE_TRIGGERS	(void *)(1UL)
+
+static void *trigger_next(struct seq_file *m, void *t, loff_t *pos)
+{
+	struct trace_event_file *event_file = event_file_data(m->private);
+
+	if (t == SHOW_AVAILABLE_TRIGGERS) {
+		(*pos)++;
+		return NULL;
+	}
+	return seq_list_next(t, &event_file->triggers, pos);
+}
+
+static bool check_user_trigger(struct trace_event_file *file)
+{
+	struct event_trigger_data *data;
+
+	list_for_each_entry_rcu(data, &file->triggers, list,
+				lockdep_is_held(&event_mutex)) {
+		if (data->flags & EVENT_TRIGGER_FL_PROBE)
+			continue;
+		return true;
+	}
+	return false;
+}
+
+static void *trigger_start(struct seq_file *m, loff_t *pos)
+{
+	struct trace_event_file *event_file;
+
+	/* ->stop() is called even if ->start() fails */
+	mutex_lock(&event_mutex);
+	event_file = event_file_data(m->private);
+	if (unlikely(!event_file))
+		return ERR_PTR(-ENODEV);
+
+	if (list_empty(&event_file->triggers) || !check_user_trigger(event_file))
+		return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;
+
+	return seq_list_start(&event_file->triggers, *pos);
+}
+
+static void trigger_stop(struct seq_file *m, void *t)
+{
+	mutex_unlock(&event_mutex);
+}
+
+static int trigger_show(struct seq_file *m, void *v)
+{
+	struct event_trigger_data *data;
+	struct event_command *p;
+
+	if (v == SHOW_AVAILABLE_TRIGGERS) {
+		seq_puts(m, "# Available triggers:\n");
+		seq_putc(m, '#');
+		mutex_lock(&trigger_cmd_mutex);
+		list_for_each_entry_reverse(p, &trigger_commands, list)
+			seq_printf(m, " %s", p->name);
+		seq_putc(m, '\n');
+		mutex_unlock(&trigger_cmd_mutex);
+		return 0;
+	}
+
+	data = list_entry(v, struct event_trigger_data, list);
+	data->ops->print(m, data);
+
+	return 0;
+}
+
+static const struct seq_operations event_triggers_seq_ops = {
+	.start = trigger_start,
+	.next = trigger_next,
+	.stop = trigger_stop,
+	.show = trigger_show,
+};
+
+static int event_trigger_regex_open(struct inode *inode, struct file *file)
+{
+	int ret;
+
+	ret = security_locked_down(LOCKDOWN_TRACEFS);
+	if (ret)
+		return ret;
+
+	mutex_lock(&event_mutex);
+
+	if (unlikely(!event_file_data(file))) {
+		mutex_unlock(&event_mutex);
+		return -ENODEV;
+	}
+
+	if ((file->f_mode & FMODE_WRITE) &&
+	    (file->f_flags & O_TRUNC)) {
+		struct trace_event_file *event_file;
+		struct event_command *p;
+
+		event_file = event_file_data(file);
+
+		list_for_each_entry(p, &trigger_commands, list) {
+			if (p->unreg_all)
+				p->unreg_all(event_file);
+		}
+	}
+
+	if (file->f_mode & FMODE_READ) {
+		ret = seq_open(file, &event_triggers_seq_ops);
+		if (!ret) {
+			struct seq_file *m = file->private_data;
+			m->private = file;
+		}
+	}
+
+	mutex_unlock(&event_mutex);
+
+	return ret;
+}
+
+int trigger_process_regex(struct trace_event_file *file, char *buff)
+{
+	char *command, *next;
+	struct event_command *p;
+	int ret = -EINVAL;
+
+	next = buff = skip_spaces(buff);
+	command = strsep(&next, ": \t");
+	if (next) {
+		next = skip_spaces(next);
+		if (!*next)
+			next = NULL;
+	}
+	command = (command[0] != '!') ? command : command + 1;
+
+	mutex_lock(&trigger_cmd_mutex);
+	list_for_each_entry(p, &trigger_commands, list) {
+		if (strcmp(p->name, command) == 0) {
+			ret = p->parse(p, file, buff, command, next);
+			goto out_unlock;
+		}
+	}
+ out_unlock:
+	mutex_unlock(&trigger_cmd_mutex);
+
+	return ret;
+}
+
+static ssize_t event_trigger_regex_write(struct file *file,
+					 const char __user *ubuf,
+					 size_t cnt, loff_t *ppos)
+{
+	struct trace_event_file *event_file;
+	ssize_t ret;
+	char *buf;
+
+	if (!cnt)
+		return 0;
+
+	if (cnt >= PAGE_SIZE)
+		return -EINVAL;
+
+	buf = memdup_user_nul(ubuf, cnt);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	strim(buf);
+
+	mutex_lock(&event_mutex);
+	event_file = event_file_data(file);
+	if (unlikely(!event_file)) {
+		mutex_unlock(&event_mutex);
+		kfree(buf);
+		return -ENODEV;
+	}
+	ret = trigger_process_regex(event_file, buf);
+	mutex_unlock(&event_mutex);
+
+	kfree(buf);
+	if (ret < 0)
+		goto out;
+
+	*ppos += cnt;
+	ret = cnt;
+ out:
+	return ret;
+}
+
+static int event_trigger_regex_release(struct inode *inode, struct file *file)
+{
+	mutex_lock(&event_mutex);
+
+	if (file->f_mode & FMODE_READ)
+		seq_release(inode, file);
+
+	mutex_unlock(&event_mutex);
+
+	return 0;
+}
+
+static ssize_t
+event_trigger_write(struct file *filp, const char __user *ubuf,
+		    size_t cnt, loff_t *ppos)
+{
+	return event_trigger_regex_write(filp, ubuf, cnt, ppos);
+}
+
+static int
+event_trigger_open(struct inode *inode, struct file *filp)
+{
+	/* Checks for tracefs lockdown */
+	return event_trigger_regex_open(inode, filp);
+}
+
+static int
+event_trigger_release(struct inode *inode, struct file *file)
+{
+	return event_trigger_regex_release(inode, file);
+}
+
+const struct file_operations event_trigger_fops = {
+	.open = event_trigger_open,
+	.read = seq_read,
+	.write = event_trigger_write,
+	.llseek = tracing_lseek,
+	.release = event_trigger_release,
+};
+
+/*
+ * Currently we only register event commands from __init, so mark this
+ * __init too.
+ */
+__init int register_event_command(struct event_command *cmd)
+{
+	struct event_command *p;
+	int ret = 0;
+
+	mutex_lock(&trigger_cmd_mutex);
+	list_for_each_entry(p, &trigger_commands, list) {
+		if (strcmp(cmd->name, p->name) == 0) {
+			ret = -EBUSY;
+			goto out_unlock;
+		}
+	}
+	list_add(&cmd->list, &trigger_commands);
+ out_unlock:
+	mutex_unlock(&trigger_cmd_mutex);
+
+	return ret;
+}
+
+/*
+ * Currently we only unregister event commands from __init, so mark
+ * this __init too.
+ */
+__init int unregister_event_command(struct event_command *cmd)
+{
+	struct event_command *p, *n;
+	int ret = -ENODEV;
+
+	mutex_lock(&trigger_cmd_mutex);
+	list_for_each_entry_safe(p, n, &trigger_commands, list) {
+		if (strcmp(cmd->name, p->name) == 0) {
+			ret = 0;
+			list_del_init(&p->list);
+			goto out_unlock;
+		}
+	}
+ out_unlock:
+	mutex_unlock(&trigger_cmd_mutex);
+
+	return ret;
+}
+
+/**
+ * event_trigger_print - Generic event_trigger_ops @print implementation
+ * @name: The name of the event trigger
+ * @m: The seq_file being printed to
+ * @data: Trigger-specific data
+ * @filter_str: filter_str to print, if present
+ *
+ * Common implementation for event triggers to print themselves.
+ *
+ * Usually wrapped by a function that simply sets the @name of the
+ * trigger command and then invokes this.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+static int
+event_trigger_print(const char *name, struct seq_file *m,
+		    void *data, char *filter_str)
+{
+	long count = (long)data;
+
+	seq_puts(m, name);
+
+	if (count == -1)
+		seq_puts(m, ":unlimited");
+	else
+		seq_printf(m, ":count=%ld", count);
+
+	if (filter_str)
+		seq_printf(m, " if %s\n", filter_str);
+	else
+		seq_putc(m, '\n');
+
+	return 0;
+}
+
+/**
+ * event_trigger_init - Generic event_trigger_ops @init implementation
+ * @data: Trigger-specific data
+ *
+ * Common implementation of event trigger initialization.
+ *
+ * Usually used directly as the @init method in event trigger
+ * implementations.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+int event_trigger_init(struct event_trigger_data *data)
+{
+	data->ref++;
+	return 0;
+}
+
+/**
+ * event_trigger_free - Generic event_trigger_ops @free implementation
+ * @data: Trigger-specific data
+ *
+ * Common implementation of event trigger de-initialization.
+ *
+ * Usually used directly as the @free method in event trigger
+ * implementations.
+ */
+static void
+event_trigger_free(struct event_trigger_data *data)
+{
+	if (WARN_ON_ONCE(data->ref <= 0))
+		return;
+
+	data->ref--;
+	if (!data->ref)
+		trigger_data_free(data);
+}
+
+int trace_event_trigger_enable_disable(struct trace_event_file *file,
+				       int trigger_enable)
+{
+	int ret = 0;
+
+	if (trigger_enable) {
+		if (atomic_inc_return(&file->tm_ref) > 1)
+			return ret;
+		set_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
+		ret = trace_event_enable_disable(file, 1, 1);
+	} else {
+		if (atomic_dec_return(&file->tm_ref) > 0)
+			return ret;
+		clear_bit(EVENT_FILE_FL_TRIGGER_MODE_BIT, &file->flags);
+		ret = trace_event_enable_disable(file, 0, 1);
+	}
+
+	return ret;
+}
+
+/**
+ * clear_event_triggers - Clear all triggers associated with a trace array
+ * @tr: The trace array to clear
+ *
+ * For each trigger, the triggering event has its tm_ref decremented
+ * via trace_event_trigger_enable_disable(), and any associated event
+ * (in the case of enable/disable_event triggers) will have its sm_ref
+ * decremented via free()->trace_event_enable_disable().  That
+ * combination effectively reverses the soft-mode/trigger state added
+ * by trigger registration.
+ *
+ * Must be called with event_mutex held.
+ */
+void
+clear_event_triggers(struct trace_array *tr)
+{
+	struct trace_event_file *file;
+
+	list_for_each_entry(file, &tr->events, list) {
+		struct event_trigger_data *data, *n;
+		list_for_each_entry_safe(data, n, &file->triggers, list) {
+			trace_event_trigger_enable_disable(file, 0);
+			list_del_rcu(&data->list);
+			if (data->ops->free)
+				data->ops->free(data);
+		}
+	}
+}
+
+/**
+ * update_cond_flag - Set or reset the TRIGGER_COND bit
+ * @file: The trace_event_file associated with the event
+ *
+ * If an event has triggers and any of those triggers has a filter or
+ * a post_trigger, trigger invocation needs to be deferred until after
+ * the current event has logged its data, and the event should have
+ * its TRIGGER_COND bit set, otherwise the TRIGGER_COND bit should be
+ * cleared.
+ */
+void update_cond_flag(struct trace_event_file *file)
+{
+	struct event_trigger_data *data;
+	bool set_cond = false;
+
+	lockdep_assert_held(&event_mutex);
+
+	list_for_each_entry(data, &file->triggers, list) {
+		if (data->filter || event_command_post_trigger(data->cmd_ops) ||
+		    event_command_needs_rec(data->cmd_ops)) {
+			set_cond = true;
+			break;
+		}
+	}
+
+	if (set_cond)
+		set_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
+	else
+		clear_bit(EVENT_FILE_FL_TRIGGER_COND_BIT, &file->flags);
+}
+
+/**
+ * register_trigger - Generic event_command @reg implementation
+ * @glob: The raw string used to register the trigger
+ * @data: Trigger-specific data to associate with the trigger
+ * @file: The trace_event_file associated with the event
+ *
+ * Common implementation for event trigger registration.
+ *
+ * Usually used directly as the @reg method in event command
+ * implementations.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+static int register_trigger(char *glob,
+			    struct event_trigger_data *data,
+			    struct trace_event_file *file)
+{
+	struct event_trigger_data *test;
+	int ret = 0;
+
+	lockdep_assert_held(&event_mutex);
+
+	list_for_each_entry(test, &file->triggers, list) {
+		if (test->cmd_ops->trigger_type == data->cmd_ops->trigger_type) {
+			ret = -EEXIST;
+			goto out;
+		}
+	}
+
+	if (data->ops->init) {
+		ret = data->ops->init(data);
+		if (ret < 0)
+			goto out;
+	}
+
+	list_add_rcu(&data->list, &file->triggers);
+
+	update_cond_flag(file);
+	ret = trace_event_trigger_enable_disable(file, 1);
+	if (ret < 0) {
+		list_del_rcu(&data->list);
+		update_cond_flag(file);
+	}
+out:
+	return ret;
+}
+
+/**
+ * unregister_trigger - Generic event_command @unreg implementation
+ * @glob: The raw string used to register the trigger
+ * @test: Trigger-specific data used to find the trigger to remove
+ * @file: The trace_event_file associated with the event
+ *
+ * Common implementation for event trigger unregistration.
+ *
+ * Usually used directly as the @unreg method in event command
+ * implementations.
+ */
+static void unregister_trigger(char *glob,
+			       struct event_trigger_data *test,
+			       struct trace_event_file *file)
+{
+	struct event_trigger_data *data = NULL, *iter;
+
+	lockdep_assert_held(&event_mutex);
+
+	list_for_each_entry(iter, &file->triggers, list) {
+		if (iter->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
+			data = iter;
+			list_del_rcu(&data->list);
+			trace_event_trigger_enable_disable(file, 0);
+			update_cond_flag(file);
+			break;
+		}
+	}
+
+	if (data && data->ops->free)
+		data->ops->free(data);
+}
+
+/*
+ * Event trigger parsing helper functions.
+ *
+ * These functions help make it easier to write an event trigger
+ * parsing function i.e. the struct event_command.parse() callback
+ * function responsible for parsing and registering a trigger command
+ * written to the 'trigger' file.
+ *
+ * A trigger command (or just 'trigger' for short) takes the form:
+ *   [trigger] [if filter]
+ *
+ * The struct event_command.parse() callback (and other struct
+ * event_command functions) refer to several components of a trigger
+ * command.  Those same components are referenced by the event trigger
+ * parsing helper functions defined below.  These components are:
+ *
+ *   cmd               - the trigger command name
+ *   glob              - the trigger command name optionally prefaced with '!'
+ *   param_and_filter  - text following cmd and ':'
+ *   param             - text following cmd and ':' and stripped of filter
+ *   filter            - the optional filter text following (and including) 'if'
+ *
+ * To illustrate the use of these componenents, here are some concrete
+ * examples. For the following triggers:
+ *
+ *   echo 'traceon:5 if pid == 0' > trigger
+ *     - 'traceon' is both cmd and glob
+ *     - '5 if pid == 0' is the param_and_filter
+ *     - '5' is the param
+ *     - 'if pid == 0' is the filter
+ *
+ *   echo 'enable_event:sys:event:n' > trigger
+ *     - 'enable_event' is both cmd and glob
+ *     - 'sys:event:n' is the param_and_filter
+ *     - 'sys:event:n' is the param
+ *     - there is no filter
+ *
+ *   echo 'hist:keys=pid if prio > 50' > trigger
+ *     - 'hist' is both cmd and glob
+ *     - 'keys=pid if prio > 50' is the param_and_filter
+ *     - 'keys=pid' is the param
+ *     - 'if prio > 50' is the filter
+ *
+ *   echo '!enable_event:sys:event:n' > trigger
+ *     - 'enable_event' the cmd
+ *     - '!enable_event' is the glob
+ *     - 'sys:event:n' is the param_and_filter
+ *     - 'sys:event:n' is the param
+ *     - there is no filter
+ *
+ *   echo 'traceoff' > trigger
+ *     - 'traceoff' is both cmd and glob
+ *     - there is no param_and_filter
+ *     - there is no param
+ *     - there is no filter
+ *
+ * There are a few different categories of event trigger covered by
+ * these helpers:
+ *
+ *  - triggers that don't require a parameter e.g. traceon
+ *  - triggers that do require a parameter e.g. enable_event and hist
+ *  - triggers that though they may not require a param may support an
+ *    optional 'n' param (n = number of times the trigger should fire)
+ *    e.g.: traceon:5 or enable_event:sys:event:n
+ *  - triggers that do not support an 'n' param e.g. hist
+ *
+ * These functions can be used or ignored as necessary - it all
+ * depends on the complexity of the trigger, and the granularity of
+ * the functions supported reflects the fact that some implementations
+ * may need to customize certain aspects of their implementations and
+ * won't need certain functions.  For instance, the hist trigger
+ * implementation doesn't use event_trigger_separate_filter() because
+ * it has special requirements for handling the filter.
+ */
+
+/**
+ * event_trigger_check_remove - check whether an event trigger specifies remove
+ * @glob: The trigger command string, with optional remove(!) operator
+ *
+ * The event trigger callback implementations pass in 'glob' as a
+ * parameter.  This is the command name either with or without a
+ * remove(!)  operator.  This function simply parses the glob and
+ * determines whether the command corresponds to a trigger removal or
+ * a trigger addition.
+ *
+ * Return: true if this is a remove command, false otherwise
+ */
+bool event_trigger_check_remove(const char *glob)
+{
+	return (glob && glob[0] == '!') ? true : false;
+}
+
+/**
+ * event_trigger_empty_param - check whether the param is empty
+ * @param: The trigger param string
+ *
+ * The event trigger callback implementations pass in 'param' as a
+ * parameter.  This corresponds to the string following the command
+ * name minus the command name.  This function can be called by a
+ * callback implementation for any command that requires a param; a
+ * callback that doesn't require a param can ignore it.
+ *
+ * Return: true if this is an empty param, false otherwise
+ */
+bool event_trigger_empty_param(const char *param)
+{
+	return !param;
+}
+
+/**
+ * event_trigger_separate_filter - separate an event trigger from a filter
+ * @param_and_filter: String containing trigger and possibly filter
+ * @param: outparam, will be filled with a pointer to the trigger
+ * @filter: outparam, will be filled with a pointer to the filter
+ * @param_required: Specifies whether or not the param string is required
+ *
+ * Given a param string of the form '[trigger] [if filter]', this
+ * function separates the filter from the trigger and returns the
+ * trigger in @param and the filter in @filter.  Either the @param
+ * or the @filter may be set to NULL by this function - if not set to
+ * NULL, they will contain strings corresponding to the trigger and
+ * filter.
+ *
+ * There are two cases that need to be handled with respect to the
+ * passed-in param: either the param is required, or it is not
+ * required.  If @param_required is set, and there's no param, it will
+ * return -EINVAL.  If @param_required is not set and there's a param
+ * that starts with a number, that corresponds to the case of a
+ * trigger with :n (n = number of times the trigger should fire) and
+ * the parsing continues normally; otherwise the function just returns
+ * and assumes param just contains a filter and there's nothing else
+ * to do.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+int event_trigger_separate_filter(char *param_and_filter, char **param,
+				  char **filter, bool param_required)
+{
+	int ret = 0;
+
+	*param = *filter = NULL;
+
+	if (!param_and_filter) {
+		if (param_required)
+			ret = -EINVAL;
+		goto out;
+	}
+
+	/*
+	 * Here we check for an optional param. The only legal
+	 * optional param is :n, and if that's the case, continue
+	 * below. Otherwise we assume what's left is a filter and
+	 * return it as the filter string for the caller to deal with.
+	 */
+	if (!param_required && param_and_filter && !isdigit(param_and_filter[0])) {
+		*filter = param_and_filter;
+		goto out;
+	}
+
+	/*
+	 * Separate the param from the filter (param [if filter]).
+	 * Here we have either an optional :n param or a required
+	 * param and an optional filter.
+	 */
+	*param = strsep(&param_and_filter, " \t");
+
+	/*
+	 * Here we have a filter, though it may be empty.
+	 */
+	if (param_and_filter) {
+		*filter = skip_spaces(param_and_filter);
+		if (!**filter)
+			*filter = NULL;
+	}
+out:
+	return ret;
+}
+
+/**
+ * event_trigger_alloc - allocate and init event_trigger_data for a trigger
+ * @cmd_ops: The event_command operations for the trigger
+ * @cmd: The cmd string
+ * @param: The param string
+ * @private_data: User data to associate with the event trigger
+ *
+ * Allocate an event_trigger_data instance and initialize it.  The
+ * @cmd_ops are used along with the @cmd and @param to get the
+ * trigger_ops to assign to the event_trigger_data.  @private_data can
+ * also be passed in and associated with the event_trigger_data.
+ *
+ * Use event_trigger_free() to free an event_trigger_data object.
+ *
+ * Return: The trigger_data object success, NULL otherwise
+ */
+struct event_trigger_data *event_trigger_alloc(struct event_command *cmd_ops,
+					       char *cmd,
+					       char *param,
+					       void *private_data)
+{
+	struct event_trigger_data *trigger_data;
+	struct event_trigger_ops *trigger_ops;
+
+	trigger_ops = cmd_ops->get_trigger_ops(cmd, param);
+
+	trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
+	if (!trigger_data)
+		return NULL;
+
+	trigger_data->count = -1;
+	trigger_data->ops = trigger_ops;
+	trigger_data->cmd_ops = cmd_ops;
+	trigger_data->private_data = private_data;
+
+	INIT_LIST_HEAD(&trigger_data->list);
+	INIT_LIST_HEAD(&trigger_data->named_list);
+	RCU_INIT_POINTER(trigger_data->filter, NULL);
+
+	return trigger_data;
+}
+
+/**
+ * event_trigger_parse_num - parse and return the number param for a trigger
+ * @param: The param string
+ * @trigger_data: The trigger_data for the trigger
+ *
+ * Parse the :n (n = number of times the trigger should fire) param
+ * and set the count variable in the trigger_data to the parsed count.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+int event_trigger_parse_num(char *param,
+			    struct event_trigger_data *trigger_data)
+{
+	char *number;
+	int ret = 0;
+
+	if (param) {
+		number = strsep(&param, ":");
+
+		if (!strlen(number))
+			return -EINVAL;
+
+		/*
+		 * We use the callback data field (which is a pointer)
+		 * as our counter.
+		 */
+		ret = kstrtoul(number, 0, &trigger_data->count);
+	}
+
+	return ret;
+}
+
+/**
+ * event_trigger_set_filter - set an event trigger's filter
+ * @cmd_ops: The event_command operations for the trigger
+ * @file: The event file for the trigger's event
+ * @param: The string containing the filter
+ * @trigger_data: The trigger_data for the trigger
+ *
+ * Set the filter for the trigger.  If the filter is NULL, just return
+ * without error.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+int event_trigger_set_filter(struct event_command *cmd_ops,
+			     struct trace_event_file *file,
+			     char *param,
+			     struct event_trigger_data *trigger_data)
+{
+	if (param && cmd_ops->set_filter)
+		return cmd_ops->set_filter(param, trigger_data, file);
+
+	return 0;
+}
+
+/**
+ * event_trigger_reset_filter - reset an event trigger's filter
+ * @cmd_ops: The event_command operations for the trigger
+ * @trigger_data: The trigger_data for the trigger
+ *
+ * Reset the filter for the trigger to no filter.
+ */
+void event_trigger_reset_filter(struct event_command *cmd_ops,
+				struct event_trigger_data *trigger_data)
+{
+	if (cmd_ops->set_filter)
+		cmd_ops->set_filter(NULL, trigger_data, NULL);
+}
+
+/**
+ * event_trigger_register - register an event trigger
+ * @cmd_ops: The event_command operations for the trigger
+ * @file: The event file for the trigger's event
+ * @glob: The trigger command string, with optional remove(!) operator
+ * @trigger_data: The trigger_data for the trigger
+ *
+ * Register an event trigger.  The @cmd_ops are used to call the
+ * cmd_ops->reg() function which actually does the registration.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+int event_trigger_register(struct event_command *cmd_ops,
+			   struct trace_event_file *file,
+			   char *glob,
+			   struct event_trigger_data *trigger_data)
+{
+	return cmd_ops->reg(glob, trigger_data, file);
+}
+
+/**
+ * event_trigger_unregister - unregister an event trigger
+ * @cmd_ops: The event_command operations for the trigger
+ * @file: The event file for the trigger's event
+ * @glob: The trigger command string, with optional remove(!) operator
+ * @trigger_data: The trigger_data for the trigger
+ *
+ * Unregister an event trigger.  The @cmd_ops are used to call the
+ * cmd_ops->unreg() function which actually does the unregistration.
+ */
+void event_trigger_unregister(struct event_command *cmd_ops,
+			      struct trace_event_file *file,
+			      char *glob,
+			      struct event_trigger_data *trigger_data)
+{
+	cmd_ops->unreg(glob, trigger_data, file);
+}
+
+/*
+ * End event trigger parsing helper functions.
+ */
+
+/**
+ * event_trigger_parse - Generic event_command @parse implementation
+ * @cmd_ops: The command ops, used for trigger registration
+ * @file: The trace_event_file associated with the event
+ * @glob: The raw string used to register the trigger
+ * @cmd: The cmd portion of the string used to register the trigger
+ * @param_and_filter: The param and filter portion of the string used to register the trigger
+ *
+ * Common implementation for event command parsing and trigger
+ * instantiation.
+ *
+ * Usually used directly as the @parse method in event command
+ * implementations.
+ *
+ * Return: 0 on success, errno otherwise
+ */
+static int
+event_trigger_parse(struct event_command *cmd_ops,
+		    struct trace_event_file *file,
+		    char *glob, char *cmd, char *param_and_filter)
+{
+	struct event_trigger_data *trigger_data;
+	char *param, *filter;
+	bool remove;
+	int ret;
+
+	remove = event_trigger_check_remove(glob);
+
+	ret = event_trigger_separate_filter(param_and_filter, &param, &filter, false);
+	if (ret)
+		return ret;
+
+	ret = -ENOMEM;
+	trigger_data = event_trigger_alloc(cmd_ops, cmd, param, file);
+	if (!trigger_data)
+		goto out;
+
+	if (remove) {
+		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
+		kfree(trigger_data);
+		ret = 0;
+		goto out;
+	}
+
+	ret = event_trigger_parse_num(param, trigger_data);
+	if (ret)
+		goto out_free;
+
+	ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
+	if (ret < 0)
+		goto out_free;
+
+	/* Up the trigger_data count to make sure reg doesn't free it on failure */
+	event_trigger_init(trigger_data);
+
+	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
+	if (ret)
+		goto out_free;
+
+	/* Down the counter of trigger_data or free it if not used anymore */
+	event_trigger_free(trigger_data);
+ out:
+	return ret;
+
+ out_free:
+	event_trigger_reset_filter(cmd_ops, trigger_data);
+	kfree(trigger_data);
+	goto out;
+}
+
+/**
+ * set_trigger_filter - Generic event_command @set_filter implementation
+ * @filter_str: The filter string for the trigger, NULL to remove filter
+ * @trigger_data: Trigger-specific data
+ * @file: The trace_event_file associated with the event
+ *
+ * Common implementation for event command filter parsing and filter
+ * instantiation.
+ *
+ * Usually used directly as the @set_filter method in event command
+ * implementations.
+ *
+ * Also used to remove a filter (if filter_str = NULL).
+ *
+ * Return: 0 on success, errno otherwise
+ */
+int set_trigger_filter(char *filter_str,
+		       struct event_trigger_data *trigger_data,
+		       struct trace_event_file *file)
+{
+	struct event_trigger_data *data = trigger_data;
+	struct event_filter *filter = NULL, *tmp;
+	int ret = -EINVAL;
+	char *s;
+
+	if (!filter_str) /* clear the current filter */
+		goto assign;
+
+	s = strsep(&filter_str, " \t");
+
+	if (!strlen(s) || strcmp(s, "if") != 0)
+		goto out;
+
+	if (!filter_str)
+		goto out;
+
+	/* The filter is for the 'trigger' event, not the triggered event */
+	ret = create_event_filter(file->tr, file->event_call,
+				  filter_str, false, &filter);
+	/*
+	 * If create_event_filter() fails, filter still needs to be freed.
+	 * Which the calling code will do with data->filter.
+	 */
+ assign:
+	tmp = rcu_access_pointer(data->filter);
+
+	rcu_assign_pointer(data->filter, filter);
+
+	if (tmp) {
+		/* Make sure the call is done with the filter */
+		tracepoint_synchronize_unregister();
+		free_event_filter(tmp);
+	}
+
+	kfree(data->filter_str);
+	data->filter_str = NULL;
+
+	if (filter_str) {
+		data->filter_str = kstrdup(filter_str, GFP_KERNEL);
+		if (!data->filter_str) {
+			free_event_filter(rcu_access_pointer(data->filter));
+			data->filter = NULL;
+			ret = -ENOMEM;
+		}
+	}
+ out:
+	return ret;
+}
+
+static LIST_HEAD(named_triggers);
+
+/**
+ * find_named_trigger - Find the common named trigger associated with @name
+ * @name: The name of the set of named triggers to find the common data for
+ *
+ * Named triggers are sets of triggers that share a common set of
+ * trigger data.  The first named trigger registered with a given name
+ * owns the common trigger data that the others subsequently
+ * registered with the same name will reference.  This function
+ * returns the common trigger data associated with that first
+ * registered instance.
+ *
+ * Return: the common trigger data for the given named trigger on
+ * success, NULL otherwise.
+ */
+struct event_trigger_data *find_named_trigger(const char *name)
+{
+	struct event_trigger_data *data;
+
+	if (!name)
+		return NULL;
+
+	list_for_each_entry(data, &named_triggers, named_list) {
+		if (data->named_data)
+			continue;
+		if (strcmp(data->name, name) == 0)
+			return data;
+	}
+
+	return NULL;
+}
+
+/**
+ * is_named_trigger - determine if a given trigger is a named trigger
+ * @test: The trigger data to test
+ *
+ * Return: true if 'test' is a named trigger, false otherwise.
+ */
+bool is_named_trigger(struct event_trigger_data *test)
+{
+	struct event_trigger_data *data;
+
+	list_for_each_entry(data, &named_triggers, named_list) {
+		if (test == data)
+			return true;
+	}
+
+	return false;
+}
+
+/**
+ * save_named_trigger - save the trigger in the named trigger list
+ * @name: The name of the named trigger set
+ * @data: The trigger data to save
+ *
+ * Return: 0 if successful, negative error otherwise.
+ */
+int save_named_trigger(const char *name, struct event_trigger_data *data)
+{
+	data->name = kstrdup(name, GFP_KERNEL);
+	if (!data->name)
+		return -ENOMEM;
+
+	list_add(&data->named_list, &named_triggers);
+
+	return 0;
+}
+
+/**
+ * del_named_trigger - delete a trigger from the named trigger list
+ * @data: The trigger data to delete
+ */
+void del_named_trigger(struct event_trigger_data *data)
+{
+	kfree(data->name);
+	data->name = NULL;
+
+	list_del(&data->named_list);
+}
+
+static void __pause_named_trigger(struct event_trigger_data *data, bool pause)
+{
+	struct event_trigger_data *test;
+
+	list_for_each_entry(test, &named_triggers, named_list) {
+		if (strcmp(test->name, data->name) == 0) {
+			if (pause) {
+				test->paused_tmp = test->paused;
+				test->paused = true;
+			} else {
+				test->paused = test->paused_tmp;
+			}
+		}
+	}
+}
+
+/**
+ * pause_named_trigger - Pause all named triggers with the same name
+ * @data: The trigger data of a named trigger to pause
+ *
+ * Pauses a named trigger along with all other triggers having the
+ * same name.  Because named triggers share a common set of data,
+ * pausing only one is meaningless, so pausing one named trigger needs
+ * to pause all triggers with the same name.
+ */
+void pause_named_trigger(struct event_trigger_data *data)
+{
+	__pause_named_trigger(data, true);
+}
+
+/**
+ * unpause_named_trigger - Un-pause all named triggers with the same name
+ * @data: The trigger data of a named trigger to unpause
+ *
+ * Un-pauses a named trigger along with all other triggers having the
+ * same name.  Because named triggers share a common set of data,
+ * unpausing only one is meaningless, so unpausing one named trigger
+ * needs to unpause all triggers with the same name.
+ */
+void unpause_named_trigger(struct event_trigger_data *data)
+{
+	__pause_named_trigger(data, false);
+}
+
+/**
+ * set_named_trigger_data - Associate common named trigger data
+ * @data: The trigger data to associate
+ * @named_data: The common named trigger to be associated
+ *
+ * Named triggers are sets of triggers that share a common set of
+ * trigger data.  The first named trigger registered with a given name
+ * owns the common trigger data that the others subsequently
+ * registered with the same name will reference.  This function
+ * associates the common trigger data from the first trigger with the
+ * given trigger.
+ */
+void set_named_trigger_data(struct event_trigger_data *data,
+			    struct event_trigger_data *named_data)
+{
+	data->named_data = named_data;
+}
+
+struct event_trigger_data *
+get_named_trigger_data(struct event_trigger_data *data)
+{
+	return data->named_data;
+}
+
+static void
+traceon_trigger(struct event_trigger_data *data,
+		struct trace_buffer *buffer, void *rec,
+		struct ring_buffer_event *event)
+{
+	struct trace_event_file *file = data->private_data;
+
+	if (file) {
+		if (tracer_tracing_is_on(file->tr))
+			return;
+
+		tracer_tracing_on(file->tr);
+		return;
+	}
+
+	if (tracing_is_on())
+		return;
+
+	tracing_on();
+}
+
+static void
+traceon_count_trigger(struct event_trigger_data *data,
+		      struct trace_buffer *buffer, void *rec,
+		      struct ring_buffer_event *event)
+{
+	struct trace_event_file *file = data->private_data;
+
+	if (file) {
+		if (tracer_tracing_is_on(file->tr))
+			return;
+	} else {
+		if (tracing_is_on())
+			return;
+	}
+
+	if (!data->count)
+		return;
+
+	if (data->count != -1)
+		(data->count)--;
+
+	if (file)
+		tracer_tracing_on(file->tr);
+	else
+		tracing_on();
+}
+
+static void
+traceoff_trigger(struct event_trigger_data *data,
+		 struct trace_buffer *buffer, void *rec,
+		 struct ring_buffer_event *event)
+{
+	struct trace_event_file *file = data->private_data;
+
+	if (file) {
+		if (!tracer_tracing_is_on(file->tr))
+			return;
+
+		tracer_tracing_off(file->tr);
+		return;
+	}
+
+	if (!tracing_is_on())
+		return;
+
+	tracing_off();
+}
+
+static void
+traceoff_count_trigger(struct event_trigger_data *data,
+		       struct trace_buffer *buffer, void *rec,
+		       struct ring_buffer_event *event)
+{
+	struct trace_event_file *file = data->private_data;
+
+	if (file) {
+		if (!tracer_tracing_is_on(file->tr))
+			return;
+	} else {
+		if (!tracing_is_on())
+			return;
+	}
+
+	if (!data->count)
+		return;
+
+	if (data->count != -1)
+		(data->count)--;
+
+	if (file)
+		tracer_tracing_off(file->tr);
+	else
+		tracing_off();
+}
+
+static int
+traceon_trigger_print(struct seq_file *m, struct event_trigger_data *data)
+{
+	return event_trigger_print("traceon", m, (void *)data->count,
+				   data->filter_str);
+}
+
+static int
+traceoff_trigger_print(struct seq_file *m, struct event_trigger_data *data)
+{
+	return event_trigger_print("traceoff", m, (void *)data->count,
+				   data->filter_str);
+}
+
+static struct event_trigger_ops traceon_trigger_ops = {
+	.trigger		= traceon_trigger,
+	.print			= traceon_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops traceon_count_trigger_ops = {
+	.trigger		= traceon_count_trigger,
+	.print			= traceon_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops traceoff_trigger_ops = {
+	.trigger		= traceoff_trigger,
+	.print			= traceoff_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops traceoff_count_trigger_ops = {
+	.trigger		= traceoff_count_trigger,
+	.print			= traceoff_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops *
+onoff_get_trigger_ops(char *cmd, char *param)
+{
+	struct event_trigger_ops *ops;
+
+	/* we register both traceon and traceoff to this callback */
+	if (strcmp(cmd, "traceon") == 0)
+		ops = param ? &traceon_count_trigger_ops :
+			&traceon_trigger_ops;
+	else
+		ops = param ? &traceoff_count_trigger_ops :
+			&traceoff_trigger_ops;
+
+	return ops;
+}
+
+static struct event_command trigger_traceon_cmd = {
+	.name			= "traceon",
+	.trigger_type		= ETT_TRACE_ONOFF,
+	.parse			= event_trigger_parse,
+	.reg			= register_trigger,
+	.unreg			= unregister_trigger,
+	.get_trigger_ops	= onoff_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static struct event_command trigger_traceoff_cmd = {
+	.name			= "traceoff",
+	.trigger_type		= ETT_TRACE_ONOFF,
+	.flags			= EVENT_CMD_FL_POST_TRIGGER,
+	.parse			= event_trigger_parse,
+	.reg			= register_trigger,
+	.unreg			= unregister_trigger,
+	.get_trigger_ops	= onoff_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+#ifdef CONFIG_TRACER_SNAPSHOT
+static void
+snapshot_trigger(struct event_trigger_data *data,
+		 struct trace_buffer *buffer, void *rec,
+		 struct ring_buffer_event *event)
+{
+	struct trace_event_file *file = data->private_data;
+
+	if (file)
+		tracing_snapshot_instance(file->tr);
+	else
+		tracing_snapshot();
+}
+
+static void
+snapshot_count_trigger(struct event_trigger_data *data,
+		       struct trace_buffer *buffer, void *rec,
+		       struct ring_buffer_event *event)
+{
+	if (!data->count)
+		return;
+
+	if (data->count != -1)
+		(data->count)--;
+
+	snapshot_trigger(data, buffer, rec, event);
+}
+
+static int
+register_snapshot_trigger(char *glob,
+			  struct event_trigger_data *data,
+			  struct trace_event_file *file)
+{
+	if (tracing_alloc_snapshot_instance(file->tr) != 0)
+		return 0;
+
+	return register_trigger(glob, data, file);
+}
+
+static int
+snapshot_trigger_print(struct seq_file *m, struct event_trigger_data *data)
+{
+	return event_trigger_print("snapshot", m, (void *)data->count,
+				   data->filter_str);
+}
+
+static struct event_trigger_ops snapshot_trigger_ops = {
+	.trigger		= snapshot_trigger,
+	.print			= snapshot_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops snapshot_count_trigger_ops = {
+	.trigger		= snapshot_count_trigger,
+	.print			= snapshot_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops *
+snapshot_get_trigger_ops(char *cmd, char *param)
+{
+	return param ? &snapshot_count_trigger_ops : &snapshot_trigger_ops;
+}
+
+static struct event_command trigger_snapshot_cmd = {
+	.name			= "snapshot",
+	.trigger_type		= ETT_SNAPSHOT,
+	.parse			= event_trigger_parse,
+	.reg			= register_snapshot_trigger,
+	.unreg			= unregister_trigger,
+	.get_trigger_ops	= snapshot_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static __init int register_trigger_snapshot_cmd(void)
+{
+	int ret;
+
+	ret = register_event_command(&trigger_snapshot_cmd);
+	WARN_ON(ret < 0);
+
+	return ret;
+}
+#else
+static __init int register_trigger_snapshot_cmd(void) { return 0; }
+#endif /* CONFIG_TRACER_SNAPSHOT */
+
+#ifdef CONFIG_STACKTRACE
+#ifdef CONFIG_UNWINDER_ORC
+/* Skip 2:
+ *   event_triggers_post_call()
+ *   trace_event_raw_event_xxx()
+ */
+# define STACK_SKIP 2
+#else
+/*
+ * Skip 4:
+ *   stacktrace_trigger()
+ *   event_triggers_post_call()
+ *   trace_event_buffer_commit()
+ *   trace_event_raw_event_xxx()
+ */
+#define STACK_SKIP 4
+#endif
+
+static void
+stacktrace_trigger(struct event_trigger_data *data,
+		   struct trace_buffer *buffer,  void *rec,
+		   struct ring_buffer_event *event)
+{
+	struct trace_event_file *file = data->private_data;
+
+	if (file)
+		__trace_stack(file->tr, tracing_gen_ctx(), STACK_SKIP);
+	else
+		trace_dump_stack(STACK_SKIP);
+}
+
+static void
+stacktrace_count_trigger(struct event_trigger_data *data,
+			 struct trace_buffer *buffer, void *rec,
+			 struct ring_buffer_event *event)
+{
+	if (!data->count)
+		return;
+
+	if (data->count != -1)
+		(data->count)--;
+
+	stacktrace_trigger(data, buffer, rec, event);
+}
+
+static int
+stacktrace_trigger_print(struct seq_file *m, struct event_trigger_data *data)
+{
+	return event_trigger_print("stacktrace", m, (void *)data->count,
+				   data->filter_str);
+}
+
+static struct event_trigger_ops stacktrace_trigger_ops = {
+	.trigger		= stacktrace_trigger,
+	.print			= stacktrace_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops stacktrace_count_trigger_ops = {
+	.trigger		= stacktrace_count_trigger,
+	.print			= stacktrace_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_trigger_free,
+};
+
+static struct event_trigger_ops *
+stacktrace_get_trigger_ops(char *cmd, char *param)
+{
+	return param ? &stacktrace_count_trigger_ops : &stacktrace_trigger_ops;
+}
+
+static struct event_command trigger_stacktrace_cmd = {
+	.name			= "stacktrace",
+	.trigger_type		= ETT_STACKTRACE,
+	.flags			= EVENT_CMD_FL_POST_TRIGGER,
+	.parse			= event_trigger_parse,
+	.reg			= register_trigger,
+	.unreg			= unregister_trigger,
+	.get_trigger_ops	= stacktrace_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static __init int register_trigger_stacktrace_cmd(void)
+{
+	int ret;
+
+	ret = register_event_command(&trigger_stacktrace_cmd);
+	WARN_ON(ret < 0);
+
+	return ret;
+}
+#else
+static __init int register_trigger_stacktrace_cmd(void) { return 0; }
+#endif /* CONFIG_STACKTRACE */
+
+static __init void unregister_trigger_traceon_traceoff_cmds(void)
+{
+	unregister_event_command(&trigger_traceon_cmd);
+	unregister_event_command(&trigger_traceoff_cmd);
+}
+
+static void
+event_enable_trigger(struct event_trigger_data *data,
+		     struct trace_buffer *buffer,  void *rec,
+		     struct ring_buffer_event *event)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+
+	if (enable_data->enable)
+		clear_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
+	else
+		set_bit(EVENT_FILE_FL_SOFT_DISABLED_BIT, &enable_data->file->flags);
+}
+
+static void
+event_enable_count_trigger(struct event_trigger_data *data,
+			   struct trace_buffer *buffer,  void *rec,
+			   struct ring_buffer_event *event)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+
+	if (!data->count)
+		return;
+
+	/* Skip if the event is in a state we want to switch to */
+	if (enable_data->enable == !(enable_data->file->flags & EVENT_FILE_FL_SOFT_DISABLED))
+		return;
+
+	if (data->count != -1)
+		(data->count)--;
+
+	event_enable_trigger(data, buffer, rec, event);
+}
+
+int event_enable_trigger_print(struct seq_file *m,
+			       struct event_trigger_data *data)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+
+	seq_printf(m, "%s:%s:%s",
+		   enable_data->hist ?
+		   (enable_data->enable ? ENABLE_HIST_STR : DISABLE_HIST_STR) :
+		   (enable_data->enable ? ENABLE_EVENT_STR : DISABLE_EVENT_STR),
+		   enable_data->file->event_call->class->system,
+		   trace_event_name(enable_data->file->event_call));
+
+	if (data->count == -1)
+		seq_puts(m, ":unlimited");
+	else
+		seq_printf(m, ":count=%ld", data->count);
+
+	if (data->filter_str)
+		seq_printf(m, " if %s\n", data->filter_str);
+	else
+		seq_putc(m, '\n');
+
+	return 0;
+}
+
+void event_enable_trigger_free(struct event_trigger_data *data)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+
+	if (WARN_ON_ONCE(data->ref <= 0))
+		return;
+
+	data->ref--;
+	if (!data->ref) {
+		/* Remove the SOFT_MODE flag */
+		trace_event_enable_disable(enable_data->file, 0, 1);
+		trace_event_put_ref(enable_data->file->event_call);
+		trigger_data_free(data);
+		kfree(enable_data);
+	}
+}
+
+static struct event_trigger_ops event_enable_trigger_ops = {
+	.trigger		= event_enable_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+static struct event_trigger_ops event_enable_count_trigger_ops = {
+	.trigger		= event_enable_count_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+static struct event_trigger_ops event_disable_trigger_ops = {
+	.trigger		= event_enable_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+static struct event_trigger_ops event_disable_count_trigger_ops = {
+	.trigger		= event_enable_count_trigger,
+	.print			= event_enable_trigger_print,
+	.init			= event_trigger_init,
+	.free			= event_enable_trigger_free,
+};
+
+int event_enable_trigger_parse(struct event_command *cmd_ops,
+			       struct trace_event_file *file,
+			       char *glob, char *cmd, char *param_and_filter)
+{
+	struct trace_event_file *event_enable_file;
+	struct enable_trigger_data *enable_data;
+	struct event_trigger_data *trigger_data;
+	struct trace_array *tr = file->tr;
+	char *param, *filter;
+	bool enable, remove;
+	const char *system;
+	const char *event;
+	bool hist = false;
+	int ret;
+
+	remove = event_trigger_check_remove(glob);
+
+	if (event_trigger_empty_param(param_and_filter))
+		return -EINVAL;
+
+	ret = event_trigger_separate_filter(param_and_filter, &param, &filter, true);
+	if (ret)
+		return ret;
+
+	system = strsep(&param, ":");
+	if (!param)
+		return -EINVAL;
+
+	event = strsep(&param, ":");
+
+	ret = -EINVAL;
+	event_enable_file = find_event_file(tr, system, event);
+	if (!event_enable_file)
+		goto out;
+
+#ifdef CONFIG_HIST_TRIGGERS
+	hist = ((strcmp(cmd, ENABLE_HIST_STR) == 0) ||
+		(strcmp(cmd, DISABLE_HIST_STR) == 0));
+
+	enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
+		  (strcmp(cmd, ENABLE_HIST_STR) == 0));
+#else
+	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+#endif
+	ret = -ENOMEM;
+
+	enable_data = kzalloc(sizeof(*enable_data), GFP_KERNEL);
+	if (!enable_data)
+		goto out;
+
+	enable_data->hist = hist;
+	enable_data->enable = enable;
+	enable_data->file = event_enable_file;
+
+	trigger_data = event_trigger_alloc(cmd_ops, cmd, param, enable_data);
+	if (!trigger_data) {
+		kfree(enable_data);
+		goto out;
+	}
+
+	if (remove) {
+		event_trigger_unregister(cmd_ops, file, glob+1, trigger_data);
+		kfree(trigger_data);
+		kfree(enable_data);
+		ret = 0;
+		goto out;
+	}
+
+	/* Up the trigger_data count to make sure nothing frees it on failure */
+	event_trigger_init(trigger_data);
+
+	ret = event_trigger_parse_num(param, trigger_data);
+	if (ret)
+		goto out_free;
+
+	ret = event_trigger_set_filter(cmd_ops, file, filter, trigger_data);
+	if (ret < 0)
+		goto out_free;
+
+	/* Don't let event modules unload while probe registered */
+	ret = trace_event_try_get_ref(event_enable_file->event_call);
+	if (!ret) {
+		ret = -EBUSY;
+		goto out_free;
+	}
+
+	ret = trace_event_enable_disable(event_enable_file, 1, 1);
+	if (ret < 0)
+		goto out_put;
+
+	ret = event_trigger_register(cmd_ops, file, glob, trigger_data);
+	if (ret)
+		goto out_disable;
+
+	event_trigger_free(trigger_data);
+ out:
+	return ret;
+ out_disable:
+	trace_event_enable_disable(event_enable_file, 0, 1);
+ out_put:
+	trace_event_put_ref(event_enable_file->event_call);
+ out_free:
+	event_trigger_reset_filter(cmd_ops, trigger_data);
+	event_trigger_free(trigger_data);
+	kfree(enable_data);
+
+	goto out;
+}
+
+int event_enable_register_trigger(char *glob,
+				  struct event_trigger_data *data,
+				  struct trace_event_file *file)
+{
+	struct enable_trigger_data *enable_data = data->private_data;
+	struct enable_trigger_data *test_enable_data;
+	struct event_trigger_data *test;
+	int ret = 0;
+
+	lockdep_assert_held(&event_mutex);
+
+	list_for_each_entry(test, &file->triggers, list) {
+		test_enable_data = test->private_data;
+		if (test_enable_data &&
+		    (test->cmd_ops->trigger_type ==
+		     data->cmd_ops->trigger_type) &&
+		    (test_enable_data->file == enable_data->file)) {
+			ret = -EEXIST;
+			goto out;
+		}
+	}
+
+	if (data->ops->init) {
+		ret = data->ops->init(data);
+		if (ret < 0)
+			goto out;
+	}
+
+	list_add_rcu(&data->list, &file->triggers);
+
+	update_cond_flag(file);
+	ret = trace_event_trigger_enable_disable(file, 1);
+	if (ret < 0) {
+		list_del_rcu(&data->list);
+		update_cond_flag(file);
+	}
+out:
+	return ret;
+}
+
+void event_enable_unregister_trigger(char *glob,
+				     struct event_trigger_data *test,
+				     struct trace_event_file *file)
+{
+	struct enable_trigger_data *test_enable_data = test->private_data;
+	struct event_trigger_data *data = NULL, *iter;
+	struct enable_trigger_data *enable_data;
+
+	lockdep_assert_held(&event_mutex);
+
+	list_for_each_entry(iter, &file->triggers, list) {
+		enable_data = iter->private_data;
+		if (enable_data &&
+		    (iter->cmd_ops->trigger_type ==
+		     test->cmd_ops->trigger_type) &&
+		    (enable_data->file == test_enable_data->file)) {
+			data = iter;
+			list_del_rcu(&data->list);
+			trace_event_trigger_enable_disable(file, 0);
+			update_cond_flag(file);
+			break;
+		}
+	}
+
+	if (data && data->ops->free)
+		data->ops->free(data);
+}
+
+static struct event_trigger_ops *
+event_enable_get_trigger_ops(char *cmd, char *param)
+{
+	struct event_trigger_ops *ops;
+	bool enable;
+
+#ifdef CONFIG_HIST_TRIGGERS
+	enable = ((strcmp(cmd, ENABLE_EVENT_STR) == 0) ||
+		  (strcmp(cmd, ENABLE_HIST_STR) == 0));
+#else
+	enable = strcmp(cmd, ENABLE_EVENT_STR) == 0;
+#endif
+	if (enable)
+		ops = param ? &event_enable_count_trigger_ops :
+			&event_enable_trigger_ops;
+	else
+		ops = param ? &event_disable_count_trigger_ops :
+			&event_disable_trigger_ops;
+
+	return ops;
+}
+
+static struct event_command trigger_enable_cmd = {
+	.name			= ENABLE_EVENT_STR,
+	.trigger_type		= ETT_EVENT_ENABLE,
+	.parse			= event_enable_trigger_parse,
+	.reg			= event_enable_register_trigger,
+	.unreg			= event_enable_unregister_trigger,
+	.get_trigger_ops	= event_enable_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static struct event_command trigger_disable_cmd = {
+	.name			= DISABLE_EVENT_STR,
+	.trigger_type		= ETT_EVENT_ENABLE,
+	.parse			= event_enable_trigger_parse,
+	.reg			= event_enable_register_trigger,
+	.unreg			= event_enable_unregister_trigger,
+	.get_trigger_ops	= event_enable_get_trigger_ops,
+	.set_filter		= set_trigger_filter,
+};
+
+static __init void unregister_trigger_enable_disable_cmds(void)
+{
+	unregister_event_command(&trigger_enable_cmd);
+	unregister_event_command(&trigger_disable_cmd);
+}
+
+static __init int register_trigger_enable_disable_cmds(void)
+{
+	int ret;
+
+	ret = register_event_command(&trigger_enable_cmd);
+	if (WARN_ON(ret < 0))
+		return ret;
+	ret = register_event_command(&trigger_disable_cmd);
+	if (WARN_ON(ret < 0))
+		unregister_trigger_enable_disable_cmds();
+
+	return ret;
+}
+
+static __init int register_trigger_traceon_traceoff_cmds(void)
+{
+	int ret;
+
+	ret = register_event_command(&trigger_traceon_cmd);
+	if (WARN_ON(ret < 0))
+		return ret;
+	ret = register_event_command(&trigger_traceoff_cmd);
+	if (WARN_ON(ret < 0))
+		unregister_trigger_traceon_traceoff_cmds();
+
+	return ret;
+}
+
+__init int register_trigger_cmds(void)
+{
+	register_trigger_traceon_traceoff_cmds();
+	register_trigger_snapshot_cmd();
+	register_trigger_stacktrace_cmd();
+	register_trigger_enable_disable_cmds();
+	register_trigger_hist_enable_disable_cmds();
+	register_trigger_hist_cmd();
+
+	return 0;
+}