linux-kernel - Re: Detecting kprobes generated code addresses

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Message-Id: <20161226133012.347f7e45dbf8a8d671ea07fb@kernel.org>
Date:   Mon, 26 Dec 2016 13:30:12 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org
Subject: Re: Detecting kprobes generated code addresses

On Sun, 25 Dec 2016 15:16:00 +0900
Masami Hiramatsu <mhiramat@...nel.org> wrote:

> On Sun, 25 Dec 2016 12:13:20 +0900
> Masami Hiramatsu <mhiramat@...nel.org> wrote:
> 
> > On Thu, 22 Dec 2016 00:42:19 -0600
> > Josh Poimboeuf <jpoimboe@...hat.com> wrote:
> > 
> > > Hi Masami,
> > > 
> > > I would like to make __kernel_text_address() be able to detect whether
> > > an address belongs to code which was generated by kprobes.  As far as I
> > > can tell, that information seems to be in the 'pages' lists of
> > > kprobe_insn_slots and kprobe_optinsn_slots.  But they seem to be
> > > protected by mutexes.
> > 
> > Right. It is currently under mutex because it may kick
> > page allocation. But I think it is easy to fix that :)
> 
> Hmm, IMHO, it seems that we should add a dummy (auto-generated)
> symbol for optprobe trampoline code to kallsyms so that
> __kernel_text_address() automatically returns true on it.

Sorry, I reconsidered this idea and conclude it was overkill.
As same as ftrace does, maybe it is enough to add a check
routine to __kernel_text_address().

Thanks,

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