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Date:   Mon, 1 Mar 2021 12:30:49 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     huangshaobo <huangshaobo6@huawei.com>
Cc:     linux@arm.linux.org.uk, mhiramat@kernel.org, tixy@linaro.org,
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        zengweilin@huawei.com, young.liuyang@huawei.com,
        nixiaoming@huawei.com, chenzefeng2@huawei.com,
        liucheng32@huawei.com, kepler.chenxin@huawei.com,
        xiaoqian9@huawei.com
Subject: Re: [PATCH 4.4.y] arm: kprobes: Allow to handle reentered kprobe on
 single-stepping
Message-ID: <YDzQaT6zTUb43LFt@kroah.com>
References: <20210227091701.23944-1-huangshaobo6@huawei.com>
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On Sat, Feb 27, 2021 at 05:17:01PM +0800, huangshaobo wrote:
> From: Masami Hiramatsu <mhiramat@kernel.org>
> 
> commit f3fbd7ec62dec1528fb8044034e2885f2b257941 upstream
> 
> This is arm port of commit 6a5022a56ac3 ("kprobes/x86: Allow to
> handle reentered kprobe on single-stepping")
> 
> Since the FIQ handlers can interrupt in the single stepping
> (or preparing the single stepping, do_debug etc.), we should
> consider a kprobe is hit in the NMI handler. Even in that
> case, the kprobe is allowed to be reentered as same as the
> kprobes hit in kprobe handlers
> (KPROBE_HIT_ACTIVE or KPROBE_HIT_SSDONE).
> 
> The real issue will happen when a kprobe hit while another
> reentered kprobe is processing (KPROBE_REENTER), because
> we already consumed a saved-area for the previous kprobe.
> 
> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
> Signed-off-by: Jon Medhurst <tixy@linaro.org>
> Fixes: 24ba613c9d6c ("ARM kprobes: core code")
> Cc: stable@vger.kernel.org #v2.6.25~v4.11
> Signed-off-by: huangshaobo <huangshaobo6@huawei.com>
> ---
>  arch/arm/probes/kprobes/core.c | 6 ++++++
>  1 file changed, 6 insertions(+)

What about the 4.9.y tree as well?

thanks,

greg k-h