selftests/ftrace: Add fgraph-multi.tc test

Add a test that creates 3 instances and enables function_graph tracer in
each as well as the top instance, where each will enable a filter (but one
that traces all functions) and check that they are filtering properly.

Link: https://lore.kernel.org/linux-trace-kernel/20240603190825.252845939@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/fgraph-multi.tc

+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: ftrace - function graph filters
+# requires: set_ftrace_filter function_graph:tracer
+
+# Make sure that function graph filtering works
+
+INSTANCE1="instances/test1_$$"
+INSTANCE2="instances/test2_$$"
+INSTANCE3="instances/test3_$$"
+
+WD=`pwd`
+
+do_reset() {
+    cd $WD
+    if [ -d $INSTANCE1 ]; then
+	echo nop > $INSTANCE1/current_tracer
+	rmdir $INSTANCE1
+    fi
+    if [ -d $INSTANCE2 ]; then
+	echo nop > $INSTANCE2/current_tracer
+	rmdir $INSTANCE2
+    fi
+    if [ -d $INSTANCE3 ]; then
+	echo nop > $INSTANCE3/current_tracer
+	rmdir $INSTANCE3
+    fi
+}
+
+mkdir $INSTANCE1
+if ! grep -q function_graph $INSTANCE1/available_tracers; then
+    echo "function_graph not allowed with instances"
+    rmdir $INSTANCE1
+    exit_unsupported
+fi
+
+mkdir $INSTANCE2
+mkdir $INSTANCE3
+
+fail() { # msg
+    do_reset
+    echo $1
+    exit_fail
+}
+
+disable_tracing
+clear_trace
+
+do_test() {
+    REGEX=$1
+    TEST=$2
+
+    # filter something, schedule is always good
+    if ! echo "$REGEX" > set_ftrace_filter; then
+	fail "can not enable filter $REGEX"
+    fi
+
+    echo > trace
+    echo function_graph > current_tracer
+    enable_tracing
+    sleep 1
+    # search for functions (has "{" or ";" on the line)
+    echo 0 > tracing_on
+    count=`cat trace | grep -v '^#' | grep -e '{' -e ';' | grep -v "$TEST" | wc -l`
+    echo 1 > tracing_on
+    if [ $count -ne 0 ]; then
+	fail "Graph filtering not working by itself against $TEST?"
+    fi
+
+    # Make sure we did find something
+    echo 0 > tracing_on
+    count=`cat trace | grep -v '^#' | grep -e '{' -e ';' | grep "$TEST" | wc -l`
+    echo 1 > tracing_on
+    if [ $count -eq 0 ]; then
+	fail "No traces found with $TEST?"
+    fi
+}
+
+do_test '*sched*' 'sched'
+cd $INSTANCE1
+do_test '*lock*' 'lock'
+cd $WD
+cd $INSTANCE2
+do_test '*rcu*' 'rcu'
+cd $WD
+cd $INSTANCE3
+echo function_graph > current_tracer
+
+sleep 1
+count=`cat trace | grep -v '^#' | grep -e '{' -e ';' | grep "$TEST" | wc -l`
+if [ $count -eq 0 ]; then
+    fail "No traces found with all tracing?"
+fi
+
+cd $WD
+echo nop > current_tracer
+echo nop > $INSTANCE1/current_tracer
+echo nop > $INSTANCE2/current_tracer
+echo nop > $INSTANCE3/current_tracer
+
+do_reset
+
+exit 0