commit 376cfa8730c08c0394d0aa1d4a80fd8c9971f323
author Tim Bird <tim.bird@am.sony.com> Sat Oct 09 22:24:38 2010 +0530
committer Rabin Vincent <rabin@rab.in> Fri Nov 19 21:43:27 2010 +0530
tree f1384eb77981241b1ab1028a50b94382c2c6e723
parent d3b9dc9dd2b994f396741f7086ffe7a48bacb165

ARM: ftrace: function graph tracer support

Cc: Tim Bird <tim.bird@am.sony.com>
[rabin@rab.in: rebase on top of latest code,
	       keep code in ftrace.c instead of separate file,
	       check for ftrace_graph_entry also]
Signed-off-by: Rabin Vincent <rabin@rab.in>

arch/arm/kernel/ftrace.c

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 971ac8c..7a702a5 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -24,6 +24,7 @@
 #define	NOP		0xe8bd4000	/* pop {lr} */
 #endif
 
+#ifdef CONFIG_DYNAMIC_FTRACE
 #ifdef CONFIG_OLD_MCOUNT
 #define OLD_MCOUNT_ADDR	((unsigned long) mcount)
 #define OLD_FTRACE_ADDR ((unsigned long) ftrace_caller_old)
@@ -193,3 +194,36 @@
 
 	return 0;
 }
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+			   unsigned long frame_pointer)
+{
+	unsigned long return_hooker = (unsigned long) &return_to_handler;
+	struct ftrace_graph_ent trace;
+	unsigned long old;
+	int err;
+
+	if (unlikely(atomic_read(&current->tracing_graph_pause)))
+		return;
+
+	old = *parent;
+	*parent = return_hooker;
+
+	err = ftrace_push_return_trace(old, self_addr, &trace.depth,
+				       frame_pointer);
+	if (err == -EBUSY) {
+		*parent = old;
+		return;
+	}
+
+	trace.func = self_addr;
+
+	/* Only trace if the calling function expects to */
+	if (!ftrace_graph_entry(&trace)) {
+		current->curr_ret_stack--;
+		*parent = old;
+	}
+}
+#endif /* CONFIG_FUNCTION_GRAPH_TRACER */