perf tests kallsyms: Add basic kallsyms test

Add test that kallsyms finds a well known symbol and fails for
another.

Signed-off-by: Ian Rogers <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>

tools/perf/tests/shell/kallsyms.sh

···
+#!/bin/bash
+# perf kallsyms tests
+# SPDX-License-Identifier: GPL-2.0
+
+err=0
+
+test_kallsyms() {
+	echo "Basic perf kallsyms test"
+
+	# Check if /proc/kallsyms is readable
+	if [ ! -r /proc/kallsyms ]; then
+		echo "Basic perf kallsyms test [Skipped: /proc/kallsyms not readable]"
+		err=2
+		return
+	fi
+
+	# Use a symbol that is definitely a function and present in all kernels, e.g. schedule
+	symbol="schedule"
+
+	# Run perf kallsyms
+	# It prints "address symbol_name"
+	output=$(perf kallsyms $symbol 2>&1)
+	ret=$?
+
+	if [ $ret -ne 0 ] || [ -z "$output" ]; then
+		# If empty or failed, it might be due to permissions (kptr_restrict)
+		# Check if we can grep the symbol from /proc/kallsyms directly
+		if grep -q "$symbol" /proc/kallsyms 2>/dev/null; then
+			# If it's in /proc/kallsyms but perf kallsyms returned empty/error,
+			# it likely means perf couldn't parse it or access it correctly (e.g. kptr_restrict=2).
+			echo "Basic perf kallsyms test [Skipped: $symbol found in /proc/kallsyms but perf kallsyms failed (output: '$output')]"
+			err=2
+			return
+		else
+			echo "Basic perf kallsyms test [Skipped: $symbol not found in /proc/kallsyms]"
+			err=2
+			return
+		fi
+	fi
+
+	if echo "$output" | grep -q "not found"; then
+		echo "Basic perf kallsyms test [Failed: output '$output' does not contain $symbol]"
+		err=1
+		return
+	fi
+
+	if perf kallsyms ErlingHaaland | grep -vq "not found"; then
+		echo "Basic perf kallsyms test [Failed: ErlingHaaland found in the output]"
+		err=1
+		return
+	fi
+	echo "Basic perf kallsyms test [Success]"
+}
+
+test_kallsyms
+exit $err