ftrace.c

Kernel code of linux kernel

				type = MATCH_END_ONLY;
				search_len = len - (i + 1);
			} else {
				if (type == MATCH_END_ONLY) {
					type = MATCH_MIDDLE_ONLY;
				} else {
					match = i;
					type = MATCH_FRONT_ONLY;
				}
				buff[i] = 0;
				break;
			}
		}
	}

	/* keep kstop machine from running */
	preempt_disable();
	if (enable)
		ftrace_filtered = 1;
	pg = ftrace_pages_start;
	while (pg) {
		for (i = 0; i < pg->index; i++) {
			int matched = 0;
			char *ptr;

			rec = &pg->records[i];
			if (rec->flags & FTRACE_FL_FAILED)
				continue;
			kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
			switch (type) {
			case MATCH_FULL:
				if (strcmp(str, buff) == 0)
					matched = 1;
				break;
			case MATCH_FRONT_ONLY:
				if (memcmp(str, buff, match) == 0)
					matched = 1;
				break;
			case MATCH_MIDDLE_ONLY:
				if (strstr(str, search))
					matched = 1;
				break;
			case MATCH_END_ONLY:
				ptr = strstr(str, search);
				if (ptr && (ptr[search_len] == 0))
					matched = 1;
				break;
			}
			if (matched)
				rec->flags |= flag;
		}
		pg = pg->next;
	}
	preempt_enable();
}

static ssize_t
ftrace_regex_write(struct file *file, const char __user *ubuf,
		   size_t cnt, loff_t *ppos, int enable)
{
	struct ftrace_iterator *iter;
	char ch;
	size_t read = 0;
	ssize_t ret;

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

	mutex_lock(&ftrace_regex_lock);

	if (file->f_mode & FMODE_READ) {
		struct seq_file *m = file->private_data;
		iter = m->private;
	} else
		iter = file->private_data;

	if (!*ppos) {
		iter->flags &= ~FTRACE_ITER_CONT;
		iter->buffer_idx = 0;
	}

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

	if (!(iter->flags & ~FTRACE_ITER_CONT)) {
		/* skip white space */
		while (cnt && isspace(ch)) {
			ret = get_user(ch, ubuf++);
			if (ret)
				goto out;
			read++;
			cnt--;
		}

		if (isspace(ch)) {
			file->f_pos += read;
			ret = read;
			goto out;
		}

		iter->buffer_idx = 0;
	}

	while (cnt && !isspace(ch)) {
		if (iter->buffer_idx < FTRACE_BUFF_MAX)
			iter->buffer[iter->buffer_idx++] = ch;
		else {
			ret = -EINVAL;
			goto out;
		}
		ret = get_user(ch, ubuf++);
		if (ret)
			goto out;
		read++;
		cnt--;
	}

	if (isspace(ch)) {
		iter->filtered++;
		iter->buffer[iter->buffer_idx] = 0;
		ftrace_match(iter->buffer, iter->buffer_idx, enable);
		iter->buffer_idx = 0;
	} else
		iter->flags |= FTRACE_ITER_CONT;


	file->f_pos += read;

	ret = read;
 out:
	mutex_unlock(&ftrace_regex_lock);

	return ret;
}

static ssize_t
ftrace_filter_write(struct file *file, const char __user *ubuf,
		    size_t cnt, loff_t *ppos)
{
	return ftrace_regex_write(file, ubuf, cnt, ppos, 1);
}

static ssize_t
ftrace_notrace_write(struct file *file, const char __user *ubuf,
		     size_t cnt, loff_t *ppos)
{
	return ftrace_regex_write(file, ubuf, cnt, ppos, 0);
}

static void
ftrace_set_regex(unsigned char *buf, int len, int reset, int enable)
{
	if (unlikely(ftrace_disabled))
		return;

	mutex_lock(&ftrace_regex_lock);
	if (reset)
		ftrace_filter_reset(enable);
	if (buf)
		ftrace_match(buf, len, enable);
	mutex_unlock(&ftrace_regex_lock);
}

/**
 * ftrace_set_filter - set a function to filter on in ftrace
 * @buf - the string that holds the function filter text.
 * @len - the length of the string.
 * @reset - non zero to reset all filters before applying this filter.
 *
 * Filters denote which functions should be enabled when tracing is enabled.
 * If @buf is NULL and reset is set, all functions will be enabled for tracing.
 */
void ftrace_set_filter(unsigned char *buf, int len, int reset)
{
	ftrace_set_regex(buf, len, reset, 1);
}

/**
 * ftrace_set_notrace - set a function to not trace in ftrace
 * @buf - the string that holds the function notrace text.
 * @len - the length of the string.
 * @reset - non zero to reset all filters before applying this filter.
 *
 * Notrace Filters denote which functions should not be enabled when tracing
 * is enabled. If @buf is NULL and reset is set, all functions will be enabled
 * for tracing.
 */
void ftrace_set_notrace(unsigned char *buf, int len, int reset)
{
	ftrace_set_regex(buf, len, reset, 0);
}

static int
ftrace_regex_release(struct inode *inode, struct file *file, int enable)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	struct ftrace_iterator *iter;

	mutex_lock(&ftrace_regex_lock);
	if (file->f_mode & FMODE_READ) {
		iter = m->private;

		seq_release(inode, file);
	} else
		iter = file->private_data;

	if (iter->buffer_idx) {
		iter->filtered++;
		iter->buffer[iter->buffer_idx] = 0;
		ftrace_match(iter->buffer, iter->buffer_idx, enable);
	}

	mutex_lock(&ftrace_sysctl_lock);
	mutex_lock(&ftraced_lock);
	if (iter->filtered && ftraced_suspend && ftrace_enabled)
		ftrace_run_update_code(FTRACE_ENABLE_CALLS);
	mutex_unlock(&ftraced_lock);
	mutex_unlock(&ftrace_sysctl_lock);

	kfree(iter);
	mutex_unlock(&ftrace_regex_lock);
	return 0;
}

static int
ftrace_filter_release(struct inode *inode, struct file *file)
{
	return ftrace_regex_release(inode, file, 1);
}

static int
ftrace_notrace_release(struct inode *inode, struct file *file)
{
	return ftrace_regex_release(inode, file, 0);
}

static ssize_t
ftraced_read(struct file *filp, char __user *ubuf,
		     size_t cnt, loff_t *ppos)
{
	/* don't worry about races */
	char *buf = ftraced_stop ? "disabled\n" : "enabled\n";
	int r = strlen(buf);

	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);
}

static ssize_t
ftraced_write(struct file *filp, const char __user *ubuf,
		      size_t cnt, loff_t *ppos)
{
	char buf[64];
	long val;
	int ret;

	if (cnt >= sizeof(buf))
		return -EINVAL;

	if (copy_from_user(&buf, ubuf, cnt))
		return -EFAULT;

	if (strncmp(buf, "enable", 6) == 0)
		val = 1;
	else if (strncmp(buf, "disable", 7) == 0)
		val = 0;
	else {
		buf[cnt] = 0;

		ret = strict_strtoul(buf, 10, &val);
		if (ret < 0)
			return ret;

		val = !!val;
	}

	if (val)
		ftrace_enable_daemon();
	else
		ftrace_disable_daemon();

	filp->f_pos += cnt;

	return cnt;
}

static struct file_operations ftrace_avail_fops = {
	.open = ftrace_avail_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = ftrace_avail_release,
};

static struct file_operations ftrace_failures_fops = {
	.open = ftrace_failures_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = ftrace_avail_release,
};

static struct file_operations ftrace_filter_fops = {
	.open = ftrace_filter_open,
	.read = ftrace_regex_read,
	.write = ftrace_filter_write,
	.llseek = ftrace_regex_lseek,
	.release = ftrace_filter_release,
};

static struct file_operations ftrace_notrace_fops = {
	.open = ftrace_notrace_open,
	.read = ftrace_regex_read,
	.write = ftrace_notrace_write,
	.llseek = ftrace_regex_lseek,
	.release = ftrace_notrace_release,
};

static struct file_operations ftraced_fops = {
	.open = tracing_open_generic,
	.read = ftraced_read,
	.write = ftraced_write,
};

/**
 * ftrace_force_update - force an update to all recording ftrace functions
 */
int ftrace_force_update(void)
{
	int ret = 0;

	if (unlikely(ftrace_disabled))
		return -ENODEV;

	mutex_lock(&ftrace_sysctl_lock);
	mutex_lock(&ftraced_lock);

	/*
	 * If ftraced_trigger is not set, then there is nothing
	 * to update.
	 */
	if (ftraced_trigger && !ftrace_update_code())
		ret = -EBUSY;

	mutex_unlock(&ftraced_lock);
	mutex_unlock(&ftrace_sysctl_lock);

	return ret;
}

static void ftrace_force_shutdown(void)
{
	struct task_struct *task;
	int command = FTRACE_DISABLE_CALLS | FTRACE_UPDATE_TRACE_FUNC;

	mutex_lock(&ftraced_lock);
	task = ftraced_task;
	ftraced_task = NULL;
	ftraced_suspend = -1;
	ftrace_run_update_code(command);
	mutex_unlock(&ftraced_lock);

	if (task)
		kthread_stop(task);
}

static __init int ftrace_init_debugfs(void)
{
	struct dentry *d_tracer;
	struct dentry *entry;

	d_tracer = tracing_init_dentry();

	entry = debugfs_create_file("available_filter_functions", 0444,
				    d_tracer, NULL, &ftrace_avail_fops);
	if (!entry)
		pr_warning("Could not create debugfs "
			   "'available_filter_functions' entry\n");

	entry = debugfs_create_file("failures", 0444,
				    d_tracer, NULL, &ftrace_failures_fops);
	if (!entry)
		pr_warning("Could not create debugfs 'failures' entry\n");

	entry = debugfs_create_file("set_ftrace_filter", 0644, d_tracer,
				    NULL, &ftrace_filter_fops);
	if (!entry)
		pr_warning("Could not create debugfs "
			   "'set_ftrace_filter' entry\n");

	entry = debugfs_create_file("set_ftrace_notrace", 0644, d_tracer,
				    NULL, &ftrace_notrace_fops);
	if (!entry)
		pr_warning("Could not create debugfs "
			   "'set_ftrace_notrace' entry\n");

	entry = debugfs_create_file("ftraced_enabled", 0644, d_tracer,
				    NULL, &ftraced_fops);
	if (!entry)
		pr_warning("Could not create debugfs "
			   "'ftraced_enabled' entry\n");
	return 0;
}

fs_initcall(ftrace_init_debugfs);

static int __init ftrace_dynamic_init(void)
{
	struct task_struct *p;
	unsigned long addr;
	int ret;

	addr = (unsigned long)ftrace_record_ip;

	stop_machine(ftrace_dyn_arch_init, &addr, NULL);

	/* ftrace_dyn_arch_init places the return code in addr */
	if (addr) {
		ret = (int)addr;
		goto failed;
	}

	ret = ftrace_dyn_table_alloc();
	if (ret)
		goto failed;

	p = kthread_run(ftraced, NULL, "ftraced");
	if (IS_ERR(p)) {
		ret = -1;
		goto failed;
	}

	last_ftrace_enabled = ftrace_enabled = 1;
	ftraced_task = p;

	return 0;

 failed:
	ftrace_disabled = 1;
	return ret;
}

core_initcall(ftrace_dynamic_init);
#else
# define ftrace_startup()		do { } while (0)
# define ftrace_shutdown()		do { } while (0)
# define ftrace_startup_sysctl()	do { } while (0)
# define ftrace_shutdown_sysctl()	do { } while (0)
# define ftrace_force_shutdown()	do { } while (0)
#endif /* CONFIG_DYNAMIC_FTRACE */

/**
 * ftrace_kill_atomic - kill ftrace from critical sections
 *
 * This function should be used by panic code. It stops ftrace
 * but in a not so nice way. If you need to simply kill ftrace
 * from a non-atomic section, use ftrace_kill.
 */
void ftrace_kill_atomic(void)
{
	ftrace_disabled = 1;
	ftrace_enabled = 0;
#ifdef CONFIG_DYNAMIC_FTRACE
	ftraced_suspend = -1;
#endif
	clear_ftrace_function();
}

/**
 * ftrace_kill - totally shutdown ftrace
 *
 * This is a safety measure. If something was detected that seems
 * wrong, calling this function will keep ftrace from doing
 * any more modifications, and updates.
 * used when something went wrong.
 */
void ftrace_kill(void)
{
	mutex_lock(&ftrace_sysctl_lock);
	ftrace_disabled = 1;
	ftrace_enabled = 0;

	clear_ftrace_function();
	mutex_unlock(&ftrace_sysctl_lock);

	/* Try to totally disable ftrace */
	ftrace_force_shutdown();
}

/**
 * register_ftrace_function - register a function for profiling
 * @ops - ops structure that holds the function for profiling.
 *
 * Register a function to be called by all functions in the
 * kernel.
 *
 * Note: @ops->func and all the functions it calls must be labeled
 *       with "notrace", otherwise it will go into a
 *       recursive loop.
 */
int register_ftrace_function(struct ftrace_ops *ops)
{
	int ret;

	if (unlikely(ftrace_disabled))
		return -1;

	mutex_lock(&ftrace_sysctl_lock);
	ret = __register_ftrace_function(ops);
	ftrace_startup();
	mutex_unlock(&ftrace_sysctl_lock);

	return ret;
}

/**
 * unregister_ftrace_function - unresgister a function for profiling.
 * @ops - ops structure that holds the function to unregister
 *
 * Unregister a function that was added to be called by ftrace profiling.
 */
int unregister_ftrace_function(struct ftrace_ops *ops)
{
	int ret;

	mutex_lock(&ftrace_sysctl_lock);
	ret = __unregister_ftrace_function(ops);
	ftrace_shutdown();
	mutex_unlock(&ftrace_sysctl_lock);

	return ret;
}

int
ftrace_enable_sysctl(struct ctl_table *table, int write,
		     struct file *file, void __user *buffer, size_t *lenp,
		     loff_t *ppos)
{
	int ret;

	if (unlikely(ftrace_disabled))
		return -ENODEV;

	mutex_lock(&ftrace_sysctl_lock);

	ret  = proc_dointvec(table, write, file, buffer, lenp, ppos);

	if (ret || !write || (last_ftrace_enabled == ftrace_enabled))
		goto out;

	last_ftrace_enabled = ftrace_enabled;

	if (ftrace_enabled) {

		ftrace_startup_sysctl();

		/* we are starting ftrace again */
		if (ftrace_list != &ftrace_list_end) {
			if (ftrace_list->next == &ftrace_list_end)
				ftrace_trace_function = ftrace_list->func;
			else
				ftrace_trace_function = ftrace_list_func;
		}

	} else {
		/* stopping ftrace calls (just send to ftrace_stub) */
		ftrace_trace_function = ftrace_stub;

		ftrace_shutdown_sysctl();
	}

 out:
	mutex_unlock(&ftrace_sysctl_lock);
	return ret;
}