linux-kernel - Re: [PATCH v2 1/2] selftests/ftrace: Add new test case which adds multiple consecutive probes in a function

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Message-Id: <20230425091213.9af554f08e607c6e43a54039@kernel.org>
Date:   Tue, 25 Apr 2023 09:12:13 +0900
From:   Masami Hiramatsu (Google) <mhiramat@...nel.org>
To:     Akanksha J N <akanksha@...ux.ibm.com>
Cc:     linux-kselftest@...r.kernel.org,
        linux-trace-kernel@...r.kernel.org, linux-kernel@...r.kernel.org,
        rostedt@...dmis.org, mhiramat@...nel.org, shuah@...nel.org,
        naveen.n.rao@...ux.ibm.com
Subject: Re: [PATCH v2 1/2] selftests/ftrace: Add new test case which adds
 multiple consecutive probes in a function

On Tue, 18 Apr 2023 15:25:56 +0530
Akanksha J N <akanksha@...ux.ibm.com> wrote:

> Commit 97f88a3d723162 ("powerpc/kprobes: Fix null pointer reference in
> arch_prepare_kprobe()") fixed a recent kernel oops that was caused as
> ftrace-based kprobe does not generate kprobe::ainsn::insn and it gets
> set to NULL.
> Add new test case kprobe_insn_boundary.tc which adds a
> kprobe at every byte within $FUNCTION_FORK up to an offset of 256 bytes,
> to be able to test potential issues with kprobes on
> successive instructions.
> The '|| continue' is added with the echo statement to ignore errors that
> are caused by trying to add kprobes to non probeable lines and continue
> with the test.

Hi Akanksha,

Thanks for adding test case. This looks good to me.

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

> Signed-off-by: Akanksha J N <akanksha@...ux.ibm.com>
> ---
>  .../test.d/kprobe/kprobe_insn_boundary.tc     | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>  create mode 100644 tools/testing/selftests/ftrace/test.d/kprobe/kprobe_insn_boundary.tc
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_insn_boundary.tc b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_insn_boundary.tc
> new file mode 100644
> index 000000000000..4f7cc318f331
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_insn_boundary.tc
> @@ -0,0 +1,19 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +# Copyright (C) 2023 Akanksha J N, IBM corporation
> +# description: Register multiple kprobe events in a function
> +# requires: kprobe_events
> +
> +for i in `seq 0 255`; do
> +  echo p $FUNCTION_FORK+${i} >> kprobe_events || continue
> +done
> +
> +cat kprobe_events >> $testlog
> +
> +echo 1 > events/kprobes/enable
> +( echo "forked" )
> +echo 0 > events/kprobes/enable
> +echo > kprobe_events
> +echo "Waiting for unoptimizing & freeing"
> +sleep 5
> +echo "Done"
> -- 
> 2.31.1
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>