perf tests top: Add basic perf top coverage test

The test starts a backgroup thloop workload and monitors it using
cpu-clock ensuring test_loop appears in the output.

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

tools/perf/tests/shell/top.sh

@@ -0,0 +1,74 @@
+#!/bin/bash
+# perf top tests
+# SPDX-License-Identifier: GPL-2.0
+
+set -e
+
+err=0
+log_file=$(mktemp /tmp/perf.top.log.XXXXX)
+
+cleanup() {
+	rm -f "${log_file}"
+	trap - EXIT TERM INT
+}
+
+trap_cleanup() {
+	echo "Unexpected signal in ${FUNCNAME[1]}"
+	cleanup
+	exit 1
+}
+trap trap_cleanup EXIT TERM INT
+
+test_basic_perf_top() {
+	echo "Basic perf top test"
+
+	# Start a workload that spins to generate samples
+	# thloop runs for the specified number of seconds
+	perf test -w thloop 20 &
+	PID=$!
+
+	# Allow it to start
+	sleep 0.1
+
+	# Run perf top for 5 seconds, monitoring that PID
+	# Use --stdio to avoid TUI and redirect output
+	# Use -d 1 to avoid flooding output
+	# Use -e cpu-clock to ensure we get samples
+	# Use sleep to keep stdin open but silent, preventing EOF loop or interactive spam
+	if ! sleep 10 | timeout 5s perf top --stdio -d 1 -e cpu-clock -p $PID > "${log_file}" 2>&1; then
+		retval=$?
+		if [ $retval -ne 124 ] && [ $retval -ne 0 ]; then
+			echo "Basic perf top test [Failed: perf top failed to start or run (ret=$retval)]"
+			head -n 50 "${log_file}"
+			kill $PID
+			wait $PID 2>/dev/null || true
+			err=1
+			return
+		fi
+	fi
+
+	kill $PID
+	wait $PID 2>/dev/null || true
+
+	# Check for some sample data (percentage)
+	if ! grep -E -q "[0-9]+\.[0-9]+%" "${log_file}"; then
+		echo "Basic perf top test [Failed: no sample percentage found]"
+		head -n 50 "${log_file}"
+		err=1
+		return
+	fi
+
+	# Check for the symbol
+	if ! grep -q "test_loop" "${log_file}"; then
+		echo "Basic perf top test [Failed: test_loop symbol not found]"
+		head -n 50 "${log_file}"
+		err=1
+		return
+	fi
+
+	echo "Basic perf top test [Success]"
+}
+
+test_basic_perf_top
+cleanup
+exit $err