linux-kernel - Re: livepatch/kprobes incompatibility

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Message-Id: <20160825002319.43769195b85c943981d4ec8b@kernel.org>
Date:   Thu, 25 Aug 2016 00:23:19 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Jessica Yu <jeyu@...hat.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: livepatch/kprobes incompatibility

On Wed, 24 Aug 2016 11:39:59 +0200
Petr Mladek <pmladek@...e.com> wrote:

> Well, there is one more problem. We should also warn when a kprobe
> is not longer accessible because the function call is redirected
> by a livepatch. My last notes about it are:
> 
>   + worked on the check for lost Kprobes; decided that only Kprobe
>     knows about all probes and need to be informed about patching;
>     added KPROBE_FLAG_PATCHED and its handling; it will be used
>     by a fake probe that will just signalize that the function is
>     patched; added helper functions that will register and unregister
>     that fake probe; the patchset still needs some clean up before
>     sending

I think the warning is acceptable but no need to update by flag,
since the livepatch can be removed and kprobes can come back again.
Moreover, at the lower level like kprobes, user might want to use
it for monitoring that the patched code is actually not executed,
like security inspection.

Thank you,


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