linux-kernel - [PATCH V2] perf test: Add a perf event fallback test

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251112164823.80168-1-zide.chen@intel.com>
Date: Wed, 12 Nov 2025 08:48:23 -0800
From: Zide Chen <zide.chen@...el.com>
To: Namhyung Kim <namhyung@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Ingo Molnar <mingo@...hat.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Ian Rogers <irogers@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org,
	thomas.falcon@...el.com,
	dapeng1.mi@...ux.intel.com,
	xudong.hao@...el.com,
	Zide Chen <zide.chen@...el.com>
Subject: [PATCH V2] perf test: Add a perf event fallback test

This adds test cases to verify the precise ip fallback logic:

- If the system supports precise ip, for an event given with the maximum
  precision level, it should be able to decrease precise_ip to find a
  supported level.
- The same fallback behavior should also work in more complex scenarios,
  such as event groups or when PEBS is involved

Additional fallback tests, such as those covering missing feature cases,
can be added in the future.

Suggested-by: Ian Rogers <irogers@...gle.com>
Reviewed-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Signed-off-by: Zide Chen <zide.chen@...el.com>
---
v2:
- Incorporated Namhyung's suggestion to change cycles:ppp to cycles:P

 .../tests/shell/test_event_open_fallback.sh   | 86 +++++++++++++++++++
 1 file changed, 86 insertions(+)
 create mode 100755 tools/perf/tests/shell/test_event_open_fallback.sh

diff --git a/tools/perf/tests/shell/test_event_open_fallback.sh b/tools/perf/tests/shell/test_event_open_fallback.sh
new file mode 100755
index 000000000000..9c411153c01b
--- /dev/null
+++ b/tools/perf/tests/shell/test_event_open_fallback.sh
@@ -0,0 +1,86 @@
+#!/bin/bash
+# Perf event open fallback test
+# SPDX-License-Identifier: GPL-2.0
+
+skip_cnt=0
+ok_cnt=0
+err_cnt=0
+
+cleanup()
+{
+	rm -f perf.data
+	rm -f perf.data.old
+	trap - EXIT TERM INT
+}
+
+trap_cleanup()
+{
+	cleanup
+	exit 1
+}
+
+trap trap_cleanup EXIT TERM INT
+
+perf_record()
+{
+	perf record "$@" -- true 1>/dev/null 2>&1
+}
+
+test_decrease_precise_ip()
+{
+	echo "Decrease precise ip test"
+
+	perf list pmu | grep -q 'cycles' || return 2
+
+	if ! perf_record -e cycles; then
+		return 2
+	fi
+
+	# It should reduce precision level down to 0 if needed.
+	if ! perf_record -e cycles:P; then
+		return 1
+	fi
+	return 0
+}
+
+test_decrease_precise_ip_complicated()
+{
+	echo "Decrease precise ip test (complicated case)"
+
+	perf list pmu | grep -q 'mem-loads-aux' || return 2
+
+	if ! perf_record -e '{cpu/mem-loads-aux/S,cpu/mem-loads/PS}'; then
+		return 1
+	fi
+	return 0
+}
+
+count_result()
+{
+	if [ "$1" -eq 2 ] ; then
+		skip_cnt=$((skip_cnt + 1))
+		return
+	fi
+	if [ "$1" -eq 0 ] ; then
+		ok_cnt=$((ok_cnt + 1))
+		return
+	fi
+	err_cnt=$((err_cnt + 1))
+}
+
+ret=0
+test_decrease_precise_ip		|| ret=$? ; count_result $ret ; ret=0
+test_decrease_precise_ip_complicated	|| ret=$? ; count_result $ret ; ret=0
+
+cleanup
+
+if [ ${err_cnt} -gt 0 ] ; then
+	exit 1
+fi
+
+if [ ${ok_cnt} -gt 0 ] ; then
+	exit 0
+fi
+
+# Skip
+exit 2
-- 
2.51.1