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, 11 insertions, 0 deletions

diff --git a/arch/microblaze/kernel/Makefile b/arch/microblaze/kernel/Makefile
index c465a5c4669..d5ee3264cd7 100644
--- a/arch/microblaze/kernel/Makefile
+++ b/arch/microblaze/kernel/Makefile
@@ -2,6 +2,16 @@
 # Makefile
 #
 
+ifdef CONFIG_FUNCTION_TRACER
+# Do not trace early boot code and low level code
+CFLAGS_REMOVE_timer.o = -pg
+CFLAGS_REMOVE_intc.o = -pg
+CFLAGS_REMOVE_early_printk.o = -pg
+CFLAGS_REMOVE_selfmod.o = -pg
+CFLAGS_REMOVE_heartbeat.o = -pg
+CFLAGS_REMOVE_ftrace.o = -pg
+endif
+
 extra-y := head.o vmlinux.lds
 
 obj-y += exceptions.o \
@@ -17,5 +27,6 @@ obj-$(CONFIG_HEART_BEAT)	+= heartbeat.o
 obj-$(CONFIG_MODULES)           += microblaze_ksyms.o module.o
 obj-$(CONFIG_MMU)               += misc.o
 obj-$(CONFIG_STACKTRACE)        += stacktrace.o
+obj-$(CONFIG_FUNCTION_TRACER)   += mcount.o
 
 obj-y   += entry$(MMU).o