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From:   Tiezhu Yang <yangtiezhu@loongson.cn>
To:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Shuah Khan <shuah@kernel.org>
Cc:     Xuefeng Li <lixuefeng@loongson.cn>, linux-mips@vger.kernel.org,
        linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] selftests/ftrace: Save kprobe_events to test log
Date:   Thu,  5 May 2022 20:19:07 +0800
Message-Id: <1651753148-1464-2-git-send-email-yangtiezhu@loongson.cn>
In-Reply-To: <1651753148-1464-1-git-send-email-yangtiezhu@loongson.cn>
References: <1651753148-1464-1-git-send-email-yangtiezhu@loongson.cn>
Precedence: bulk

It may lead to kernel panic when execute the following testcase on mips:

  # ./ftracetest test.d/kprobe/multiple_kprobes.tc

A preliminary analysis shows that the issue is related with

  echo 1 > events/kprobes/enable

after add the 256 probe points.

In order to find the root cause, I want to verify which probe point has
problem, so it is necessary to save kprobe_events to test log.

With this patch, we can get the 256 probe points in the test log through
the following command:

  # ./ftracetest test.d/kprobe/multiple_kprobes.tc -vvv -k

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
---
 tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc b/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
index 312d237..be754f5 100644
--- a/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
+++ b/tools/testing/selftests/ftrace/test.d/kprobe/multiple_kprobes.tc
@@ -25,6 +25,8 @@ if [ $L -ne 256 ]; then
   exit_fail
 fi
 
+cat kprobe_events >> $testlog
+
 echo 1 > events/kprobes/enable
 echo 0 > events/kprobes/enable
 echo > kprobe_events
-- 
2.1.0