Release 4.15 kernel/trace/trace_events_trigger.c

/*
 * trace_events_trigger - trace event triggers
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) 2013 Tom Zanussi <tom.zanussi@linux.intel.com>
 */

#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);

	synchronize_sched(); /* make sure current triggers exit before free */
	kfree(data);
}

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/**
 * 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, void *rec)
{
	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->func(data, rec);
			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->func(data, rec);
	}
	return tt;
}
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EXPORT_SYMBOL_GPL(event_triggers_call);

/**
 * 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
 * @rec: The trace entry for the event
 *
 * 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,
			 void *rec)
{
	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->func(data, rec);
	}
}
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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)
		return NULL;

	return seq_list_next(t, &event_file->triggers, pos);
}

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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))
		return *pos == 0 ? SHOW_AVAILABLE_TRIGGERS : NULL;

	return seq_list_start(&event_file->triggers, *pos);
}

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static void trigger_stop(struct seq_file *m, void *t)
{
	mutex_unlock(&event_mutex);
}

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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->ops, data);

	return 0;
}

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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 = 0;

	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;
}

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static int trigger_process_regex(struct trace_event_file *file, char *buff)
{
	char *command, *next = buff;
	struct event_command *p;
	int ret = -EINVAL;

	command = strsep(&next, ": \t");
	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->func(p, file, buff, command, next);
			goto out_unlock;
		}
	}
 out_unlock:
	mutex_unlock(&trigger_cmd_mutex);

	return ret;
}

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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;
}

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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;
}

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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);
}

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static int

event_trigger_open(struct inode *inode, struct file *filp)
{
	return event_trigger_regex_open(inode, filp);
}

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static int

event_trigger_release(struct inode *inode, struct file *file)
{
	return event_trigger_regex_release(inode, file);
}

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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;
}

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/*
 * 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;
}

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/**
 * 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;
}

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/**
 * event_trigger_init - Generic event_trigger_ops @init implementation
 * @ops: The trigger ops associated with the trigger
 * @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_ops *ops,
		       struct event_trigger_data *data)
{
	data->ref++;
	return 0;
}

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/**
 * event_trigger_free - Generic event_trigger_ops @free implementation
 * @ops: The trigger ops associated with the trigger
 * @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_ops *ops,
		   struct event_trigger_data *data)
{
	if (WARN_ON_ONCE(data->ref <= 0))
		return;

	data->ref--;
	if (!data->ref)
		trigger_data_free(data);
}

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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;
}

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/**
 * 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;
		list_for_each_entry_rcu(data, &file->triggers, list) {
			trace_event_trigger_enable_disable(file, 0);
			if (data->ops->free)
				data->ops->free(data->ops, data);
		}
	}
}

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/**
 * 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;

	list_for_each_entry_rcu(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);
}

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/**
 * register_trigger - Generic event_command @reg implementation
 * @glob: The raw string used to register the trigger
 * @ops: The trigger ops associated with 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_ops *ops,
			    struct event_trigger_data *data,
			    struct trace_event_file *file)
{
	struct event_trigger_data *test;
	int ret = 0;

	list_for_each_entry_rcu(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->ops, data);
		if (ret < 0)
			goto out;
	}

	list_add_rcu(&data->list, &file->triggers);
	ret++;

	update_cond_flag(file);
	if (trace_event_trigger_enable_disable(file, 1) < 0) {
		list_del_rcu(&data->list);
		update_cond_flag(file);
		ret--;
	}
out:
	return ret;
}

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/**
 * unregister_trigger - Generic event_command @unreg implementation
 * @glob: The raw string used to register the trigger
 * @ops: The trigger ops associated with 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.
 */


void unregister_trigger(char *glob, struct event_trigger_ops *ops,
			struct event_trigger_data *test,
			struct trace_event_file *file)
{
	struct event_trigger_data *data;
	bool unregistered = false;

	list_for_each_entry_rcu(data, &file->triggers, list) {
		if (data->cmd_ops->trigger_type == test->cmd_ops->trigger_type) {
			unregistered = true;
			list_del_rcu(&data->list);
			trace_event_trigger_enable_disable(file, 0);
			update_cond_flag(file);
			break;
		}
	}

	if (unregistered && data->ops->free)
		data->ops->free(data->ops, data);
}

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/**
 * event_trigger_callback - Generic event_command @func 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: The params portion of the string used to register the trigger
 *
 * Common implementation for event command parsing and trigger
 * instantiation.
 *
 * Usually used directly as the @func method in event command
 * implementations.
 *
 * Return: 0 on success, errno otherwise
 */

static int

event_trigger_callback(struct event_command *cmd_ops,
		       struct trace_event_file *file,
		       char *glob, char *cmd, char *param)
{
	struct event_trigger_data *trigger_data;
	struct event_trigger_ops *trigger_ops;
	char *trigger = NULL;
	char *number;
	int ret;

	/* separate the trigger from the filter (t:n [if filter]) */
	if (param && isdigit(param[0]))
		trigger = strsep(&param, " \t");

	trigger_ops = cmd_ops->get_trigger_ops(cmd, trigger);

	ret = -ENOMEM;
	trigger_data = kzalloc(sizeof(*trigger_data), GFP_KERNEL);
	if (!trigger_data)
		goto out;

	trigger_data->count = -1;
	trigger_data->ops = trigger_ops;
	trigger_data->cmd_ops = cmd_ops;
	INIT_LIST_HEAD(&trigger_data->list);
	INIT_LIST_HEAD(&trigger_data->named_list);

	if (glob[0] == '!') {
		cmd_ops->unreg(glob+1, trigger_ops, trigger_data, file);
		kfree(trigger_data);
		ret = 0;
		goto out;
	}

	if (trigger) {
		number = strsep(&trigger, ":");

		ret = -EINVAL;
		if (!strlen(number))
			goto out_free;

		/*
                 * We use the callback data field (which is a pointer)
                 * as our counter.
                 */
		ret = kstrtoul(number, 0, &trigger_data->count);
		if (ret)
			goto out_free;
	}

	if (!param) /* if param is non-empty, it's supposed to be a filter */
		goto out_reg;

	if (!cmd_ops->set_filter)
		goto out_reg;

	ret = cmd_ops->set_filter(param, trigger_data, file);
	if (ret < 0)
		goto out_free;

 out_reg:
	ret = cmd_ops->reg(glob, trigger_ops, trigger_data, file);
	/*
         * The above returns on success the # of functions enabled,
         * but if it didn't find any functions it returns zero.
         * Consider no functions a failure too.
         */
	if (!ret) {
		ret = -ENOENT;
		goto out_free;
	} else if (ret < 0)
		goto out_free;
	ret = 0;
 out:
	return ret;

 out_free:
	if (cmd_ops->set_filter)
		cmd_ops->set_filter(NULL, trigger_data, NULL);
	kfree(trigger_data);
	goto out;
}

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4
100.00%

/**
 * 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->event_call, filter_str, false, &filter);
	if (ret)
		goto out;
 assign:
	tmp = rcu_access_pointer(data->filter);

	rcu_assign_pointer(data->filter, filter);

	if (tmp) {
		/* Make sure the call is done with the filter */
		synchronize_sched();
		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;
}

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2
66.67%
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217
100.00%
3
100.00%

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;
}

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/**
 * 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;
}

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/**
 * 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)
{