From 6b7dca401cb148603158119c89319c85228a2a61 Mon Sep 17 00:00:00 2001
From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Tue, 21 Aug 2018 16:27:58 +0900
Subject: [PATCH] tracing: Allow gcov profiling on only ftrace subsystem

Add GCOV_PROFILE_FTRACE to allow gcov profiling on only files in ftrace
subsystem. This config option will be used for checking kselftest/ftrace
coverage.

Link: http://lkml.kernel.org/r/153483647755.32472.4746349899604275441.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/Kconfig  | 12 ++++++++++++
 kernel/trace/Makefile |  5 +++++
 2 files changed, 17 insertions(+)

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index fd6754b88f87..aec44d838283 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -774,6 +774,18 @@ config TRACING_EVENTS_GPIO
 	help
 	  Enable tracing events for gpio subsystem
 
+config GCOV_PROFILE_FTRACE
+	bool "Enable GCOV profiling on ftrace subsystem"
+	depends on GCOV_KERNEL
+	help
+	  Enable GCOV profiling on ftrace subsystem for checking
+	  which functions/lines are tested.
+
+	  If unsure, say N.
+
+	  Note that on a kernel compiled with this config, ftrace will
+	  run significantly slower.
+
 endif # FTRACE
 
 endif # TRACING_SUPPORT
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 98d53b39a8ee..f81dadbc7c4a 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -23,6 +23,11 @@ ifdef CONFIG_TRACING_BRANCHES
 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
 endif
 
+# for GCOV coverage profiling
+ifdef CONFIG_GCOV_PROFILE_FTRACE
+GCOV_PROFILE := y
+endif
+
 CFLAGS_trace_benchmark.o := -I$(src)
 CFLAGS_trace_events_filter.o := -I$(src)
 
-- 
2.50.1