[PATCH v6 21/22] tracing/boot: Add function tracer filter options

From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	Frank Rowand <frowand.list@gmail.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Namhyung Kim <namhyung@kernel.org>, Tim Bird <Tim.Bird@sony.com>,
	Jiri Olsa <jolsa@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Tom Zanussi <tom.zanussi@linux.intel.com>,
	Rob Herring <robh+dt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Alexey Dobriyan <adobriyan@gmail.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v6 21/22] tracing/boot: Add function tracer filter options
Date: Sat, 11 Jan 2020 01:07:28 +0900	[thread overview]
Message-ID: <157867244841.17873.10933616628243103561.stgit@devnote2> (raw)
In-Reply-To: <157867220019.17873.13377985653744804396.stgit@devnote2>

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@kernel.org>
---
 Changes in v6:
  - Fix to depend on CONFIG_DYNAMIC_FTRACE instead of
    CONFIG_FUNCTION_TRACER.
---
 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..fa9603dc6469 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_DYNAMIC_FTRACE
+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)

