microblaze: ftrace: add static function tracer

If -pg of gcc is enabled with CONFIG_FUNCTION_TRACER=y. a calling to
_mcount will be inserted into each kernel function. so, there is a
possibility to trace the kernel functions in _mcount.

This patch add the specific _mcount support for static function
tracing. by default, ftrace_trace_function is initialized as
ftrace_stub(an empty function), so, the default _mcount will introduce
very little overhead. after enabling ftrace in user-space, it will jump
to a real tracing function and do static function tracing for us.

Commit message from Wu Zhangjin <wuzhangjin@gmail.com>

Signed-off-by: Michal Simek <monstr@monstr.eu>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
index 57eeaa60ca69..18003ca08196 100644
--- a/arch/microblaze/Kconfig
+++ b/arch/microblaze/Kconfig
@@ -6,6 +6,7 @@ mainmenu "Linux/Microblaze Kernel Configuration"
 config MICROBLAZE
         def_bool y
         select HAVE_LMB
+        select HAVE_FUNCTION_TRACER
         select USB_ARCH_HAS_EHCI
         select ARCH_WANT_OPTIONAL_GPIOLIB