perf test cs-etm: Test process attribution

Run the context switch workload on one CPU and trace it to test that
symbols are attributed to the correct process and that the attribution
changes at the exact point that the context switch happened.

Reviewed-by: Leo Yan <leo.yan@arm.com>
Signed-off-by: James Clark <james.clark@linaro.org>
Cc: Amir Ayupov <aaupov@meta.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Mike Leach <mike.leach@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paschalis Mpeis <Paschalis.Mpeis@arm.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/shell/coresight/context_switch_thread.sh

@@ -0,0 +1,69 @@
+#!/bin/bash -e
+# CoreSight context switch thread attribution (exclusive)
+
+# SPDX-License-Identifier: GPL-2.0
+
+# If CoreSight is not available, skip the test
+perf list pmu | grep -q cs_etm || exit 2
+
+if [ "$(id -u)" != 0 ]; then
+	# Requires root for "-C 0" in record command
+	echo "[Skip] No root permission"
+	exit 2
+fi
+
+tmpdir=$(mktemp -d /tmp/__perf_test.coresight_context_switch.XXXXX)
+
+cleanup() {
+	rm -rf "${tmpdir}"
+	trap - EXIT TERM INT
+}
+
+trap_cleanup() {
+	cleanup
+	exit 1
+}
+trap trap_cleanup EXIT TERM INT
+
+check_samples() {
+	owner_samples=$(grep -c "proc1.*context_switch_loop_proc1" "$tmpdir/script" || true)
+	next_samples=$(grep -c "proc2.*context_switch_loop_proc2" "$tmpdir/script" || true)
+
+	if [ "$owner_samples" -eq 0 ] || [ "$next_samples" -eq 0 ]; then
+		echo "No samples found"
+		cleanup
+		exit 1
+	fi
+
+	if grep "proc2.*context_switch_loop_proc1" "$tmpdir/script"; then
+		echo "Thread1 symbol was attributed to proc2"
+		cleanup
+		exit 1
+	fi
+
+	if grep "proc1.*context_switch_loop_proc2" "$tmpdir/script"; then
+		echo "Thread2 symbol was attributed to proc1"
+		cleanup
+		exit 1
+	fi
+}
+
+cf="$tmpdir/ctl"
+af="$tmpdir/ack"
+mkfifo "$cf" "$af"
+
+# Pin to one CPU so the two threads alternate running but record into the same
+# trace buffer. Start disabled and use the control FIFO to only record the
+# workload and not startup.
+perf record -o "$tmpdir/data" -e cs_etm/timestamp=0/u -C 0 -D -1 --control fifo:"$cf","$af" -- \
+	taskset --cpu-list 0 perf test --record-ctl fifo:"$cf","$af" \
+	-w context_switch_loop > /dev/null 2>&1
+
+# Test both instruction and branch sample generation modes.
+perf script -i "$tmpdir/data" --itrace=i4 -F comm,pid,tid,ip,sym > "$tmpdir/script" 2>/dev/null
+check_samples
+perf script -i "$tmpdir/data" --itrace=b -F comm,pid,tid,ip,sym > "$tmpdir/script" 2>/dev/null
+check_samples
+
+cleanup
+exit 0