linux-kernel - [RFC PATCH v4 21/22] tracing/boot: Add function tracer filter options

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Message-Id: <157528183338.22451.2725921016653118215.stgit@devnote2>
Date:   Mon,  2 Dec 2019 19:17:13 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>,
        Frank Rowand <frowand.list@...il.com>
Cc:     Ingo Molnar <mingo@...hat.com>, Namhyung Kim <namhyung@...nel.org>,
        Tim Bird <Tim.Bird@...y.com>, Jiri Olsa <jolsa@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Tom Zanussi <tom.zanussi@...ux.intel.com>,
        Rob Herring <robh+dt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Jonathan Corbet <corbet@....net>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-doc@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH v4 21/22] tracing/boot: Add function tracer filter options

Add below function-tracer filter options to boot-time tracing.

 - ftrace.[instance.INSTANCE.]ftrace.filters
   This will take an array of tracing function filter rules

 - ftrace.[instance.INSTANCE.]ftrace.notraces
   This will take an array of NON-tracing function filter rules

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
---
 kernel/trace/trace_boot.c |   40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/kernel/trace/trace_boot.c b/kernel/trace/trace_boot.c
index 81d923c16a4d..57274b9b3718 100644
--- a/kernel/trace/trace_boot.c
+++ b/kernel/trace/trace_boot.c
@@ -244,11 +244,51 @@ trace_boot_init_events(struct trace_array *tr, struct xbc_node *node)
 #define trace_boot_init_events(tr, node) do {} while (0)
 #endif
 
+#ifdef CONFIG_FUNCTION_TRACER
+extern bool ftrace_filter_param __initdata;
+extern int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
+			     int len, int reset);
+extern int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
+			      int len, int reset);
+static void __init
+trace_boot_set_ftrace_filter(struct trace_array *tr, struct xbc_node *node)
+{
+	struct xbc_node *anode;
+	const char *p;
+	char *q;
+
+	xbc_node_for_each_array_value(node, "ftrace.filters", anode, p) {
+		q = kstrdup(p, GFP_KERNEL);
+		if (!q)
+			return;
+		if (ftrace_set_filter(tr->ops, q, strlen(q), 0) < 0)
+			pr_err("Failed to add %s to ftrace filter\n", p);
+		else
+			ftrace_filter_param = true;
+		kfree(q);
+	}
+	xbc_node_for_each_array_value(node, "ftrace.notraces", anode, p) {
+		q = kstrdup(p, GFP_KERNEL);
+		if (!q)
+			return;
+		if (ftrace_set_notrace(tr->ops, q, strlen(q), 0) < 0)
+			pr_err("Failed to add %s to ftrace filter\n", p);
+		else
+			ftrace_filter_param = true;
+		kfree(q);
+	}
+}
+#else
+#define trace_boot_set_ftrace_filter(tr, node) do {} while (0)
+#endif
+
 static void __init
 trace_boot_enable_tracer(struct trace_array *tr, struct xbc_node *node)
 {
 	const char *p;
 
+	trace_boot_set_ftrace_filter(tr, node);
+
 	p = xbc_node_find_value(node, "tracer", NULL);
 	if (p && *p != '\0') {
 		if (tracing_set_tracer(tr, p) < 0)