perf tests script dlfilter: Add a dlfilter test

Compile a simple dlfilter and make sure it remove samples from
everything other than a test_loop.

Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

Author: captain5050

tools/perf/tests/shell/script_dlfilter.sh

@@ -0,0 +1,107 @@
+#!/bin/bash
+# perf script --dlfilter tests
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+
+shelldir=$(dirname "$0")
+# shellcheck source=lib/setup_python.sh
+. "${shelldir}"/lib/setup_python.sh
+
+# skip if there's no compiler
+if ! [ -x "$(command -v cc)" ]; then
+	echo "failed: no compiler, install gcc"
+	exit 2
+fi
+
+err=0
+perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
+dlfilter_c=$(mktemp /tmp/__perf_test.dlfilter.test.c.XXXXX)
+dlfilter_so=$(mktemp /tmp/__perf_test.dlfilter.so.XXXXX)
+
+cleanup() {
+	rm -f "${perfdata}"
+	rm -f "${dlfilter_c}"
+	rm -f "${dlfilter_so}"
+	rm -f "${dlfilter_so}.o"
+
+	trap - EXIT TERM INT
+}
+
+trap_cleanup() {
+	echo "Unexpected signal in ${FUNCNAME[1]}"
+	cleanup
+	exit 1
+}
+trap trap_cleanup EXIT TERM INT
+
+cat <<EOF > "${dlfilter_c}"
+#include <perf/perf_dlfilter.h>
+#include <string.h>
+#include <stdio.h>
+
+struct perf_dlfilter_fns perf_dlfilter_fns;
+
+int filter_event(void *data, const struct perf_dlfilter_sample *sample, void *ctx)
+{
+	const struct perf_dlfilter_al *al;
+
+	if (!sample->ip)
+		return 0;
+
+	al = perf_dlfilter_fns.resolve_ip(ctx);
+	if (!al || !al->sym || strcmp(al->sym, "test_loop"))
+		return 1;
+
+	return 0;
+}
+EOF
+
+test_dlfilter() {
+	echo "Basic --dlfilter test"
+	# Generate perf.data file
+	if ! perf record -o "${perfdata}" perf test -w thloop 1 2> /dev/null
+	then
+		echo "Basic --dlfilter test [Failed record]"
+		err=1
+		return
+	fi
+
+	# Build the dlfilter
+	if ! cc -c -I tools/perf/include -fpic -x c "${dlfilter_c}" -o "${dlfilter_so}.o"
+	then
+		echo "Basic --dlfilter test [Failed to build dlfilter object]"
+		err=1
+		return
+	fi
+
+	if ! cc -shared -o "${dlfilter_so}" "${dlfilter_so}.o"
+	then
+		echo "Basic --dlfilter test [Failed to link dlfilter shared object]"
+		err=1
+		return
+	fi
+
+	# Check that the output contains "test_loop" and nothing else
+	if ! perf script -i "${perfdata}" --dlfilter "${dlfilter_so}" | grep -q "test_loop"
+	then
+		echo "Basic --dlfilter test [Failed missing output]"
+		err=1
+		return
+	fi
+
+	# The filter should filter out everything except test_loop, so ensure no other symbols are present
+	# This is a simple check; we could be more rigorous
+	if perf script -i "${perfdata}" --dlfilter "${dlfilter_so}" | grep -v "test_loop" | grep -q "perf"
+	then
+		echo "Basic --dlfilter test [Failed filtering]"
+		err=1
+		return
+	fi
+
+	echo "Basic --dlfilter test [Success]"
+}
+
+test_dlfilter
+cleanup
+exit $err