ftrace: add pretty print to selected fuction traces

This patch adds a call back for the tracers that have hooks to
selected functions. This allows the tracer to show better output
in the set_ftrace_filter file.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>

include/linux/ftrace.h

@@ -106,12 +106,18 @@ struct ftrace_func_command {
 /* asm/ftrace.h must be defined for archs supporting dynamic ftrace */
 #include <asm/ftrace.h>
 
+struct seq_file;
+
 struct ftrace_hook_ops {
 	void			(*func)(unsigned long ip,
 					unsigned long parent_ip,
 					void **data);
 	int			(*callback)(unsigned long ip, void **data);
 	void			(*free)(void **data);
+	int			(*print)(struct seq_file *m,
+					 unsigned long ip,
+					 struct ftrace_hook_ops *ops,
+					 void *data);
 };
 
 extern int

kernel/trace/ftrace.c

@@ -834,6 +834,9 @@ static int t_hash_show(struct seq_file *m, void *v)
 
 	rec = hlist_entry(hnd, struct ftrace_func_hook, node);
 
+	if (rec->ops->print)
+		return rec->ops->print(m, rec->ip, rec->ops, rec->data);
+
 	kallsyms_lookup(rec->ip, NULL, NULL, NULL, str);
 	seq_printf(m, "%s:", str);