path: root/kernel/trace/trace_events.c

/*
 * event tracer
 *
 * Copyright (C) 2008 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
 *
 *  - Added format output of fields of the trace point.
 *    This was based off of work by Tom Zanussi <tzanussi@gmail.com>.
 *
 */

#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/kthread.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/delay.h>

#include <asm/setup.h>

#include "trace_output.h"

#undef TRACE_SYSTEM
#define TRACE_SYSTEM "TRACE_SYSTEM"

DEFINE_MUTEX(event_mutex);

LIST_HEAD(ftrace_events);

int trace_define_field(struct ftrace_event_call *call, const char *type,
		       const char *name, int offset, int size, int is_signed,
		       int filter_type)
{
	struct ftrace_event_field *field;

	field = kzalloc(sizeof(*field), GFP_KERNEL);
	if (!field)
		goto err;

	field->name = kstrdup(name, GFP_KERNEL);
	if (!field->name)
		goto err;

	field->type = kstrdup(type, GFP_KERNEL);
	if (!field->type)
		goto err;

	if (filter_type == FILTER_OTHER)
		field->filter_type = filter_assign_type(type);
	else
		field->filter_type = filter_type;

	field->offset = offset;
	field->size = size;
	field->is_signed = is_signed;

	list_add(&field->link, &call->fields);

	return 0;

err:
	if (field) {
		kfree(field->name);
		kfree(field->type);
	}
	kfree(field);

	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(trace_define_field);

#define __common_field(type, item)					\
	ret = trace_define_field(call, #type, "common_" #item,		\
				 offsetof(typeof(ent), item),		\
				 sizeof(ent.item),			\
				 is_signed_type(type), FILTER_OTHER);	\
	if (ret)							\
		return ret;

static int trace_define_common_fields(struct ftrace_event_call *call)
{
	int ret;
	struct trace_entry ent;

	__common_field(unsigned short, type);
	__common_field(unsigned char, flags);
	__common_field(unsigned char, preempt_count);
	__common_field(int, pid);
	__common_field(int, lock_depth);

	return ret;
}

void trace_destroy_fields(struct ftrace_event_call *call)
{
	struct ftrace_event_field *field, *next;

	list_for_each_entry_safe(field, next, &call->fields, link) {
		list_del(&field->link);
		kfree(field->type);
		kfree(field->name);
		kfree(field);
	}
}

int trace_event_raw_init(struct ftrace_event_call *call)
{
	int id;

	id = register_ftrace_event(call->event);
	if (!id)
		return -ENODEV;
	call->id = id;
	INIT_LIST_HEAD(&call->fields);

	return 0;
}
EXPORT_SYMBOL_GPL(trace_event_raw_init);

static int ftrace_event_enable_disable(struct ftrace_event_call *call,
					int enable)
{
	int ret = 0;

	switch (enable) {
	case 0:
		if (call->enabled) {
			call->enabled = 0;
			tracing_stop_cmdline_record();
			call->unregfunc(call);
		}
		break;
	case 1:
		if (!call->enabled) {
			tracing_start_cmdline_record();
			ret = call->regfunc(call);
			if (ret) {
				tracing_stop_cmdline_record();
				pr_info("event trace: Could not enable event "
					"%s\n", call->name);
				break;
			}
			call->enabled = 1;
		}
		break;
	}

	return ret;
}

static void ftrace_clear_events(void)
{
	struct ftrace_event_call *call;

	mutex_lock(&event_mutex);
	list_for_each_entry(call, &ftrace_events, list) {
		ftrace_event_enable_disable(call, 0);
	}
	mutex_unlock(&event_mutex);
}

/*
 * __ftrace_set_clr_event(NULL, NULL, NULL, set) will set/unset all events.
 */
static int __ftrace_set_clr_event(const char *match, const char *sub,
				  const char *event, int set)
{
	struct ftrace_event_call *call;
	int ret = -EINVAL;

	mutex_lock(&event_mutex);
	list_for_each_entry(call, &ftrace_events, list) {

		if (!call->name || !call->regfunc)
			continue;

		if (match &&
		    strcmp(match, call->name) != 0 &&
		    strcmp(match, call->system) != 0)
			continue;

		if (sub && strcmp(sub, call->system) != 0)
			continue;

		if (event && strcmp(event, call->name) != 0)
			continue;

		ftrace_event_enable_disable(call, set);

		ret = 0;
	}
	mutex_unlock(&event_mutex);

	return ret;
}

static int ftrace_set_clr_event(char *buf, int set)
{
	char *event = NULL, *sub = NULL, *match;

	/*
	 * The buf format can be <subsystem>:<event-name>
	 *  *:<event-name> means any event by that name.
	 *  :<event-name> is the same.
	 *
	 *  <subsystem>:* means all events in that subsystem
	 *  <subsystem>: means the same.
	 *
	 *  <name> (no ':') means all events in a subsystem with
	 *  the name <name> or any event that matches <name>
	 */

	match = strsep(&buf, ":");
	if (buf) {
		sub = match;
		event = buf;
		match = NULL;

		if (!strlen(sub) || strcmp(sub, "*") == 0)
			sub = NULL;
		if (!strlen(event) || strcmp(event, "*") == 0)
			event = NULL;
	}

	return __ftrace_set_clr_event(match, sub, event, set);
}

/**
 * trace_set_clr_event - enable or disable an event
 * @system: system name to match (NULL for any system)
 * @event: event name to match (NULL for all events, within system)
 * @set: 1 to enable, 0 to disable
 *
 * This is a way for other parts of the kernel to enable or disable
 * event recording.
 *
 * Returns 0 on success, -EINVAL if the parameters do not match any
 * registered events.
 */
int trace_set_clr_event(const char *system, const char *event, int set)
{
	return __ftrace_set_clr_event(NULL, system, event, set);
}

/* 128 should be much more than enough */
#define EVENT_BUF_SIZE		127

static ssize_t
ftrace_event_write(struct file *file, const char __user *ubuf,
		   size_t cnt, loff_t *ppos)
{
	struct trace_parser parser;
	ssize_t read, ret;

	if (!cnt)
		return 0;

	ret = tracing_update_buffers();
	if (ret < 0)
		return ret;

	if (trace_parser_get_init(&parser, EVENT_BUF_SIZE + 1))
		return -ENOMEM;

	read = trace_get_user(&parser, ubuf, cnt, ppos);

	if (read >= 0 && trace_parser_loaded((&parser))) {
		int set = 1;

		if (*parser.buffer == '!')
			set = 0;

		parser.buffer[parser.idx] = 0;

		ret = ftrace_set_clr_event(parser.buffer + !set, set);
		if (ret)
			goto out_put;
	}

	ret = read;

 out_put:
	trace_parser_put(&parser);

	return ret;
}

static void *
t_next(struct seq_file *m, void *v, loff_t *pos)
{
	struct ftrace_event_call *call = v;

	(*pos)++;

	list_for_each_entry_continue(call, &ftrace_events, list) {
		/*
		 * The ftrace subsystem is for showing formats only.
		 * They can not be enabled or disabled via the event files.
		 */
		if (call->regfunc)
			return call;
	}

	return NULL;
}

static void *t_start(struct seq_file *m, loff_t *pos)
{
	struct ftrace_event_call *call;
	loff_t l;

	mutex_lock(&event_mutex);

	call = list_entry(&ftrace_events, struct ftrace_event_call, list);
	for (l = 0; l <= *pos; ) {
		call = t_next(m, call, &l);
		if (!call)
			break;
	}
	return call;
}

static void *
s_