selftests/ftrace: Add function profiling stat testcase

Add a testcase for function profiling per-cpu statistics
interface. There is already func_profile.tc, but that is
mainly focusing on the combination of function-profiler
and function tracer. This testcase ensures trace_stat
per-cpu function statistics is correctly updated.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/ftrace/test.d/ftrace/func_profile_stat.tc

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: ftrace - function profiling
+
+[ ! -f function_profile_enabled ] && exit_unsupported
+
+: "Enable function profile"
+echo 1 > function_profile_enabled
+
+: "Profile must be updated"
+cp trace_stat/function0 $TMPDIR/
+( echo "forked"; sleep 1 )
+: "diff returns 0 if there is no difference"
+! diff trace_stat/function0 $TMPDIR/function0
+
+echo 0 > function_profile_enabled
+
+: "Profile must NOT be updated"
+cp trace_stat/function0 $TMPDIR/
+( echo "forked"; sleep 1 )
+: "diff returns 0 if there is no difference"
+diff trace_stat/function0 $TMPDIR/function0