linux-kernel - Re: [PATCH v8 4/5] selftests/ftrace: Add selftest for testing eprobe events

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Date:   Fri, 20 Aug 2021 09:46:39 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-kernel@...r.kernel.org, linux-trace-devel@...r.kernel.org,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        "Tzvetomir Stoyanov" <tz.stoyanov@...il.com>,
        Tom Zanussi <zanussi@...nel.org>,
        Shuah Khan <shuah@...nel.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v8 4/5] selftests/ftrace: Add selftest for testing
 eprobe events

On Thu, 19 Aug 2021 11:26:08 -0400
Steven Rostedt <rostedt@...dmis.org> wrote:

> From: "Steven Rostedt (VMware)" <rostedt@...dmis.org>
> 
> Add a test to test event probes, by creating a synthetic event across
> sys_enter_openat and sys_exit_openat that passes the filename pointer from
> the enter of the system call to the exit, and then add an event probe to
> the synthetic event to make sure that the file name is seen.
> 
> Link: https://lkml.kernel.org/r/20210819041842.884828019@goodmis.org
> 
> Cc: Shuah Khan <shuah@...nel.org>
> Cc: Shuah Khan <skhan@...uxfoundation.org>
> Cc: linux-kselftest@...r.kernel.org
> Signed-off-by: Steven Rostedt (VMware) <rostedt@...dmis.org>
> ---
>  .../test.d/dynevent/add_remove_eprobe.tc      | 53 +++++++++++++++++++
>  1 file changed, 53 insertions(+)
>  create mode 100644 tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc
> new file mode 100644
> index 000000000000..7b242f29b916
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_eprobe.tc
> @@ -0,0 +1,53 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: Generic dynamic event - add/remove eprobe events
> +# requires: dynamic_events "e[:[<group>/]<event>] <attached-group>.<attached-event> [<args>]":README
> +
> +echo 0 > events/enable
> +
> +clear_dynamic_events
> +
> +SYSTEM="syscalls"
> +START="sys_enter_openat"
> +END="sys_exit_openat"
> +FIELD="filename"
> +SYNTH="synth_open"
> +EPROBE="eprobe_open"
> +
> +echo "$SYNTH u64 filename; s64 ret;" > synthetic_events
> +echo "hist:keys=common_pid:__arg__1=$FIELD" > events/$SYSTEM/$START/trigger
> +echo "hist:keys=common_pid:filename=\$__arg__1,ret=ret:onmatch($SYSTEM.$START).trace($SYNTH,\$filename,\$ret)" > events/$SYSTEM/$END/trigger

Hmm, can you make this more simple one without synthetic events?
Since synthetic event depends on CONFIG_SYNTH_EVENTS, you need to add
"synth_events" to 'requires' tag.
However, this means that this testcase doesn't run when CONFIG_SYNTH_EVENTS=n
but CONFIG_*PROBE_EVENTS=y.

Thank you,

> +
> +echo "e:$EPROBE synthetic/$SYNTH file=+0(\$filename):ustring ret=\$ret:s64" >> dynamic_events
> +
> +grep -q "$SYNTH" dynamic_events
> +grep -q "$EPROBE" dynamic_events
> +test -d events/synthetic/$SYNTH
> +test -d events/eprobes/$EPROBE
> +
> +echo 1 > events/eprobes/$EPROBE/enable
> +ls
> +echo 0 > events/eprobes/$EPROBE/enable
> +
> +content=`grep '^ *ls-' trace | grep 'file='`
> +nocontent=`grep '^ *ls-' trace | grep 'file=' | grep -v -e '"/' -e '"."'` || true
> +
> +if [ -z "$content" ]; then
> +	exit_fail
> +fi
> +
> +if [ ! -z "$nocontent" ]; then
> +	exit_fail
> +fi
> +
> +echo "-:$EPROBE" >> dynamic_events
> +echo '!'"hist:keys=common_pid:filename=\$__arg__1,ret=ret:onmatch($SYSTEM.$START).trace($SYNTH,\$filename,\$ret)" > events/$SYSTEM/$END/trigger
> +echo '!'"hist:keys=common_pid:__arg__1=$FIELD" > events/$SYSTEM/$START/trigger
> +echo '!'"$SYNTH u64 filename; s64 ret;" >> synthetic_events
> +
> +! grep -q "$SYNTH" dynamic_events
> +! grep -q "$EPROBE" dynamic_events
> +! test -d events/synthetic/$SYNTH
> +! test -d events/eprobes/$EPROBE
> +
> +clear_trace
> -- 
> 2.30.2


-- 
Masami Hiramatsu <mhiramat@...nel.org>