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

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Message-ID: <20190214155522.GA1825@fuggles.cambridge.arm.com>
Date:   Thu, 14 Feb 2019 15:55:22 +0000
From:   Will Deacon <will.deacon@....com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
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()

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).
 */

With that, you can have my ack for the series:

Acked-by: Will Deacon <will.deacon@....com>

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

Cheers,

Will