linux-kernel - Re: [patch V3 04/23] kprobes: Prevent probes in .noinstr.text section

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Date:   Tue, 24 Mar 2020 10:47:30 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Paul McKenney <paulmck@...nel.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        "Joel Fernandes \(Google\)" <joel@...lfernandes.org>,
        "Steven Rostedt \(VMware\)" <rostedt@...dmis.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Frederic Weisbecker <frederic@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Brian Gerst <brgerst@...il.com>,
        Juergen Gross <jgross@...e.com>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org
Subject: Re: [patch V3 04/23] kprobes: Prevent probes in .noinstr.text section

Masami Hiramatsu <mhiramat@...nel.org> writes:
> On Mon, 23 Mar 2020 17:03:24 +0100
> Thomas Gleixner <tglx@...utronix.de> wrote:
>> > @@ -2212,6 +2212,10 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
>> >  	ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
>> >  					(unsigned long)__kprobes_text_end);
>> >  
>> > +	/* Symbols in noinstr section are blacklisted */
>> > +	ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
>> > +					(unsigned long)__noinstr_text_end);
>> > +
>> >  	return ret ? : arch_populate_kprobe_blacklist();
>> >  }
>> 
>> So that extra function is not required when adding that, right?
>
> That's right :)
>
>> 
>> >> +/* Functions in .noinstr.text must not be probed */
>> >> +static bool within_noinstr_text(unsigned long addr)
>> >> +{
>> >> +	/* FIXME: Handle module .noinstr.text */
>
> And this reminds me that the module .kprobes.text is not handled yet :(.

Correct. Any idea how to do that with a simple oneliner like the above?

Thanks,

        tglx