selftests/ftrace: Add function_graph tracer to func-filter-pid test

The function tracer is tested to see if pid filtering works. Add a test to
test function_graph tracer as well, but only if the function_graph tracer
is enabled for the top level or instance.

Link: https://lore.kernel.org/linux-trace-kernel/20240603190825.083048115@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc

@@ -14,6 +14,11 @@ if [ ! -f options/function-fork ]; then
     echo "no option for function-fork found. Option will not be tested."
 fi
 
+if [ ! -f options/funcgraph-proc ]; then
+    do_funcgraph_proc=0
+    echo "no option for function-fork found. Option will not be tested."
+fi
+
 read PID _ < /proc/self/stat
 
 if [ $do_function_fork -eq 1 ]; then
@@ -21,12 +26,18 @@ if [ $do_function_fork -eq 1 ]; then
     orig_value=`grep function-fork trace_options`
 fi
 
+if [ $do_funcgraph_proc -eq 1 ]; then
+    orig_value2=`cat options/funcgraph-proc`
+fi
+
 do_reset() {
-    if [ $do_function_fork -eq 0 ]; then
-	return
+    if [ $do_function_fork -eq 1 ]; then
+	echo $orig_value > trace_options
     fi
 
-    echo $orig_value > trace_options
+    if [ $do_funcgraph_proc -eq 1 ]; then
+	echo $orig_value2 > options/funcgraph-proc
+    fi
 }
 
 fail() { # msg
@@ -36,13 +47,15 @@ fail() { # msg
 }
 
 do_test() {
+    TRACER=$1
+
     disable_tracing
 
     echo do_execve* > set_ftrace_filter
     echo $FUNCTION_FORK >> set_ftrace_filter
 
     echo $PID > set_ftrace_pid
-    echo function > current_tracer
+    echo $TRACER > current_tracer
 
     if [ $do_function_fork -eq 1 ]; then
 	# don't allow children to be traced
@@ -82,7 +95,11 @@ do_test() {
     fi
 }
 
-do_test
+do_test function
+if grep -s function_graph available_tracers; then
+    do_test function_graph
+fi
+
 do_reset
 
 exit 0