Commit e66ed86c authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Steven Rostedt (VMware)
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tracing/boot: Add per-event histogram action options 

Add a hist-trigger action syntax support to boot-time tracing.
Currently, boot-time tracing supports per-event actions as option
strings. However, for the histogram action, it has a special syntax
and usually needs a long action definition.
To make it readable and fit to the bootconfig syntax, this introduces
a new options for histogram.

Here are the histogram action options for boot-time tracing.

ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {
     keys = <KEY>[,...]
     values = <VAL>[,...]
     sort = <SORT-KEY>[,...]
     size = <ENTRIES>
     name = <HISTNAME>
     var { <VAR> = <EXPR> ... }
     pause|continue|clear
     onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] }
     onmatch { event = <EVENT>; <ACTION> [= <PARAM>] }
     filter = <FILTER>
}

Where <ACTION> is one of below;

     trace = <EVENT>, <ARG1>[, ...]
     save = <ARG1>[, ...]
     snapshot

Link: https://lkml.kernel.org/r/162856124106.203126.10501871028479029087.stgit@devnote2



Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent c3b1c377

kernel/trace/trace_boot.c

+231 −0
Original line number Diff line number Diff line
@@ -171,6 +171,231 @@ trace_boot_add_synth_event(struct xbc_node *node, const char *event) 
}

#endif



#ifdef CONFIG_HIST_TRIGGERS

static int __init __printf(3, 4)

append_printf(char **bufp, char *end, const char *fmt, ...)

{

	va_list args;

	int ret;



	if (*bufp == end)

		return -ENOSPC;



	va_start(args, fmt);

	ret = vsnprintf(*bufp, end - *bufp, fmt, args);

	if (ret < end - *bufp) {

		*bufp += ret;

	} else {

		*bufp = end;

		ret = -ERANGE;

	}

	va_end(args);



	return ret;

}



static int __init

append_str_nospace(char **bufp, char *end, const char *str)

{

	char *p = *bufp;

	int len;



	while (p < end - 1 && *str != '\0') {

		if (!isspace(*str))

			*(p++) = *str;

		str++;

	}

	*p = '\0';

	if (p == end - 1) {

		*bufp = end;

		return -ENOSPC;

	}

	len = p - *bufp;

	*bufp = p;

	return (int)len;

}



static int __init

trace_boot_hist_add_array(struct xbc_node *hnode, char **bufp,

			  char *end, const char *key)

{

	struct xbc_node *knode, *anode;

	const char *p;

	char sep;



	knode = xbc_node_find_child(hnode, key);

	if (knode) {

		anode = xbc_node_get_child(knode);

		if (!anode) {

			pr_err("hist.%s requires value(s).\n", key);

			return -EINVAL;

		}



		append_printf(bufp, end, ":%s", key);

		sep = '=';

		xbc_array_for_each_value(anode, p) {

			append_printf(bufp, end, "%c%s", sep, p);

			if (sep == '=')

				sep = ',';

		}

	} else

		return -ENOENT;



	return 0;

}



static int __init

trace_boot_hist_add_handler(struct xbc_node *hnode, char **bufp,

			    char *end, const char *param)

{

	struct xbc_node *knode, *anode;

	const char *p;

	char sep;



	/* Compose 'handler' parameter */

	p = xbc_node_find_value(hnode, param, NULL);

	if (!p) {

		pr_err("hist.%s requires '%s' option.\n",

		       xbc_node_get_data(hnode), param);

		return -EINVAL;

	}

	append_printf(bufp, end, ":%s(%s)", xbc_node_get_data(hnode), p);



	/* Compose 'action' parameter */

	knode = xbc_node_find_child(hnode, "trace");

	if (!knode)

		knode = xbc_node_find_child(hnode, "save");



	if (knode) {

		anode = xbc_node_get_child(knode);

		if (!anode || !xbc_node_is_value(anode)) {

			pr_err("hist.%s.%s requires value(s).\n",

			       xbc_node_get_data(hnode),

			       xbc_node_get_data(knode));

			return -EINVAL;

		}



		append_printf(bufp, end, ".%s", xbc_node_get_data(knode));

		sep = '(';

		xbc_array_for_each_value(anode, p) {

			append_printf(bufp, end, "%c%s", sep, p);

			if (sep == '(')

				sep = ',';

		}

		append_printf(bufp, end, ")");

	} else if (xbc_node_find_child(hnode, "snapshot")) {

		append_printf(bufp, end, ".snapshot()");

	} else {

		pr_err("hist.%s requires an action.\n",

		       xbc_node_get_data(hnode));

		return -EINVAL;

	}



	return 0;

}



/*

 * Histogram boottime tracing syntax.

 *

 * ftrace.[instance.INSTANCE.]event.GROUP.EVENT.hist {

 *	keys = <KEY>[,...]

 *	values = <VAL>[,...]

 *	sort = <SORT-KEY>[,...]

 *	size = <ENTRIES>

 *	name = <HISTNAME>

 *	var { <VAR> = <EXPR> ... }

 *	pause|continue|clear

 *	onmax|onchange { var = <VAR>; <ACTION> [= <PARAM>] }

 *	onmatch { event = <EVENT>; <ACTION> [= <PARAM>] }

 *	filter = <FILTER>

 * }

 *

 * Where <ACTION> are;

 *

 *	trace = <EVENT>, <ARG1>[, ...]

 *	save = <ARG1>[, ...]

 *	snapshot

 */

static int __init

trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)

{

	struct xbc_node *node, *knode;

	char *end = buf + size;

	const char *p;

	int ret = 0;



	append_printf(&buf, end, "hist");



	ret = trace_boot_hist_add_array(hnode, &buf, end, "keys");

	if (ret < 0) {

		if (ret == -ENOENT)

			pr_err("hist requires keys.\n");

		return -EINVAL;

	}



	ret = trace_boot_hist_add_array(hnode, &buf, end, "values");

	if (ret == -EINVAL)

		return ret;

	ret = trace_boot_hist_add_array(hnode, &buf, end, "sort");

	if (ret == -EINVAL)

		return ret;



	p = xbc_node_find_value(hnode, "size", NULL);

	if (p)

		append_printf(&buf, end, ":size=%s", p);



	p = xbc_node_find_value(hnode, "name", NULL);

	if (p)

		append_printf(&buf, end, ":name=%s", p);



	node = xbc_node_find_child(hnode, "var");

	if (node) {

		xbc_node_for_each_key_value(node, knode, p) {

			/* Expression must not include spaces. */

			append_printf(&buf, end, ":%s=",

				      xbc_node_get_data(knode));

			append_str_nospace(&buf, end, p);

		}

	}



	/* Histogram control attributes (mutual exclusive) */

	if (xbc_node_find_child(hnode, "pause"))

		append_printf(&buf, end, ":pause");

	else if (xbc_node_find_child(hnode, "continue"))

		append_printf(&buf, end, ":continue");

	else if (xbc_node_find_child(hnode, "clear"))

		append_printf(&buf, end, ":clear");



	/* Histogram handler and actions */

	node = xbc_node_find_child(hnode, "onmax");

	if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)

		return -EINVAL;

	node = xbc_node_find_child(hnode, "onchange");

	if (node && trace_boot_hist_add_handler(node, &buf, end, "var") < 0)

		return -EINVAL;

	node = xbc_node_find_child(hnode, "onmatch");

	if (node && trace_boot_hist_add_handler(node, &buf, end, "event") < 0)

		return -EINVAL;



	p = xbc_node_find_value(hnode, "filter", NULL);

	if (p)

		append_printf(&buf, end, " if %s", p);



	if (buf == end) {

		pr_err("hist exceeds the max command length.\n");

		return -E2BIG;

	}



	return 0;

}

#else

static int __init

trace_boot_compose_hist_cmd(struct xbc_node *hnode, char *buf, size_t size)

{

	return -EOPNOTSUPP;

}

#endif



static void __init

trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode,

			  struct xbc_node *enode)
@@ -212,6 +437,12 @@ trace_boot_init_one_event(struct trace_array *tr, struct xbc_node *gnode, 
			else if (trigger_process_regex(file, buf) < 0)

				pr_err("Failed to apply an action: %s\n", buf);

		}

		anode = xbc_node_find_child(enode, "hist");

		if (anode &&

		    trace_boot_compose_hist_cmd(anode, buf, ARRAY_SIZE(buf)) == 0) {

			if (trigger_process_regex(file, buf) < 0)

				pr_err("Failed to apply hist trigger: %s\n", buf);

		}

	} else if (xbc_node_find_value(enode, "actions", NULL))

		pr_err("Failed to apply event actions because CONFIG_HIST_TRIGGERS is not set.\n");