ftrace: fix dynamic ftrace selftest

With the adding of the configuration changes in the Makefile to prevent
tracing of functions in the ftrace code, all tracing of all the ftrace
code has been removed. Unfortunately, one of the selftests, relied on
a function to be traced. With the new change, the function was no longer
traced and the test failed.

This patch separates out the test function into its own file so that
we can add the "-pg" flag to the compilation of that function and the
adding of the mcount call to that function.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/trace/Makefile

@@ -4,6 +4,10 @@
 ifdef CONFIG_FTRACE
 ORIG_CFLAGS := $(KBUILD_CFLAGS)
 KBUILD_CFLAGS = $(subst -pg,,$(ORIG_CFLAGS))
+
+# selftest needs instrumentation
+CFLAGS_trace_selftest_dynamic.o = -pg
+obj-y += trace_selftest_dynamic.o
 endif
 
 obj-$(CONFIG_FTRACE) += libftrace.o

kernel/trace/trace.h

@@ -244,6 +244,8 @@ extern int unregister_tracer_switch(struct tracer_switch_ops *ops);
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 extern unsigned long ftrace_update_tot_cnt;
+#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
+extern int DYN_FTRACE_TEST_NAME(void);
 #endif
 
 #ifdef CONFIG_FTRACE_STARTUP_TEST

kernel/trace/trace_selftest.c

@@ -107,14 +107,8 @@ static int trace_test_buffer(struct trace_array *tr, unsigned long *count)
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
-#define DYN_FTRACE_TEST_NAME trace_selftest_dynamic_test_func
 #define __STR(x) #x
 #define STR(x) __STR(x)
-static int DYN_FTRACE_TEST_NAME(void)
-{
-	/* used to call mcount */
-	return 0;
-}
 
 /* Test dynamic code modification and ftrace filters */
 int trace_selftest_startup_dynamic_tracing(struct tracer *trace,

kernel/trace/trace_selftest_dynamic.c

+#include "trace.h"
+
+int DYN_FTRACE_TEST_NAME(void)
+{
+	/* used to call mcount */
+	return 0;
+}