linux-kernel - Re: [PATCH v3 4/4] arm64: kprobes: Use arch_populate_kprobe

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Message-Id: <20190216000058.a75ff4d9497065ce216e246d@kernel.org>
Date:   Sat, 16 Feb 2019 00:00:58 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Will Deacon <will.deacon@....com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Pratyush Anand <panand@...hat.com>,
        "David A . Long" <dave.long@...aro.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        James Morse <james.morse@....com>
Subject: Re: [PATCH v3 4/4] arm64: kprobes: Use
 arch_populate_kprobe_blacklist()

On Thu, 14 Feb 2019 15:55:22 +0000
Will Deacon <will.deacon@....com> wrote:

> Hi Masami,
> 
> On Wed, Feb 13, 2019 at 12:44:48AM +0900, Masami Hiramatsu wrote:
> > Use arch_populate_kprobe_blacklist() instead of
> > arch_within_kprobe_blacklist() so that we can see the full
> > blacklisted symbols under the debugfs.
> > 
> > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> > ---
> >   Changes in v3
> >    - Do not populate blacklist in __kprobe_text in
> >      arch_populate_kprobe_blacklist(), since it is already
> >      populated in populate_kprobe_blacklist().
> >    - Add exception entry text blacklist since those are rejected
> >      by in_exception_text().
> > ---
> >  arch/arm64/kernel/probes/kprobes.c |   45 +++++++++++++++++++++---------------
> >  1 file changed, 26 insertions(+), 19 deletions(-)
> > 
> > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> > index 194262fca5cd..37d913f33a89 100644
> > --- a/arch/arm64/kernel/probes/kprobes.c
> > +++ b/arch/arm64/kernel/probes/kprobes.c
> > @@ -465,26 +465,33 @@ kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr)
> >  	return DBG_HOOK_HANDLED;
> >  }
> >  
> > -bool arch_within_kprobe_blacklist(unsigned long addr)
> 
> I think it would be useful to add a comment here so that we remember
> why this code is the way it is:
> 
> /*
>  * Provide a blacklist of symbols identifying ranges which cannot be kprobed.
>  * This blacklist is exposed to userspace via debugfs (kprobes/blacklist).
>  */

Agreed. This looks good to me too.

> 
> With that, you can have my ack for the series:
> 
> Acked-by: Will Deacon <will.deacon@....com>

Thank you!

> 
> Catalin -- can you pick these up with that comment added, please?
> 
> Cheers,
> 
> Will


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