selftests/ftrace: Add function filter on module testcase

Add a testcase for function filter on module.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

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

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: ftrace - function trace on module
+
+[ ! -f set_ftrace_filter ] && exit_unsupported
+
+: "mod: allows to filter a non exist function"
+echo 'non_exist_func:mod:non_exist_module' > set_ftrace_filter
+grep -q "non_exist_func" set_ftrace_filter
+
+: "mod: on exist module"
+echo '*:mod:trace_printk' > set_ftrace_filter
+if ! modprobe trace-printk ; then
+  echo "No trace-printk sample module - please make CONFIG_SAMPLE_TRACE_PRINTK=
+m"
+  exit_unresolved;
+fi
+
+: "Wildcard should be resolved after loading module"
+grep -q "trace_printk_irq_work" set_ftrace_filter
+
+: "After removing the filter becomes empty"
+rmmod trace_printk
+test `cat set_ftrace_filter | wc -l` -eq 0