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

Link: http://lkml.kernel.org/r/157867244841.17873.10933616628243103561.stgit@devnote2Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

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)