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/debugfs.h>
#include <linux/uaccess.h>
#include <linux/module.h>
#include <linux/ctype.h>

#include "trace_output.h"

#define TRACE_SYSTEM "TRACE_SYSTEM"

static DEFINE_MUTEX(event_mutex);

int trace_define_field(struct ftrace_event_call *call, char *type,
		       char *name, int offset, int size)
{
	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;

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

	return 0;

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

	return -ENOMEM;
}

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


	while ((unsigned long)call < (unsigned long)__stop_ftrace_events) {

		if (call->enabled) {
			call->enabled = 0;
			call->unregfunc();
		}
		call++;
	}
}

static void ftrace_event_enable_disable(struct ftrace_event_call *call,
					int enable)
{

	switch (enable) {
	case 0:
		if (call->enabled) {
			call->enabled = 0;
			call->unregfunc();
		}
		break;
	case 1:
		if (!call->enabled) {
			call->enabled = 1;
			call->regfunc();
		}
		break;
	}
}

static int ftrace_set_clr_event(char *buf, int set)
{
	struct ftrace_event_call *call = __start_ftrace_events;
	char *event = NULL, *sub = NULL, *match;
	int ret = -EINVAL;

	/*
	 * 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;
	}

	mutex_lock(&event_mutex);
	for_each_event(call) {

		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;
}

/* 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)
{
	size_t read = 0;
	int i, set = 1;
	ssize_t ret;
	char *buf;
	char ch;

	if (!cnt || cnt < 0)
		return 0;

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

	ret = get_user(ch, ubuf++);
	if (ret)
		return ret;
	read++;
	cnt--;

	/* skip white space */
	while (cnt && isspace(ch)) {
		ret = get_user(ch, ubuf++);
		if (ret)
			return ret;
		read++;
		cnt--;
	}

	/* Only white space found? */
	if (isspace(ch)) {
		file->f_pos += read;
		ret = read;
		return ret;
	}

	buf = kmalloc(EVENT_BUF_SIZE+1, GFP_KERNEL);
	if (!buf)
		return -ENOMEM;

	if (cnt > EVENT_BUF_SIZE)
		cnt = EVENT_BUF_SIZE;

	i = 0;
	while (cnt && !isspace(ch)) {
		if (!i && ch == '!')
			set = 0;
		else
			buf[i++] = ch;