linux-kernel - Re: [PATCH v2 4/4] arm64: kprobes: Use arch_populate_kprobe

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Date:   Fri, 8 Feb 2019 09:15:19 +0000
From:   Will Deacon <will.deacon@....com>
To:     Masami Hiramatsu <mhiramat@...nel.org>
Cc:     James Morse <james.morse@....com>,
        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>
Subject: Re: [PATCH v2 4/4] arm64: kprobes: Use
 arch_populate_kprobe_blacklist()

Hi Masami,

On Mon, Jan 21, 2019 at 10:25:58PM +0900, Masami Hiramatsu wrote:
> On Mon, 21 Jan 2019 12:20:07 +0000
> James Morse <james.morse@....com> wrote:
> > On 15/01/2019 06:25, 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.
> > > diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> > > index b9e9758b6534..6c066c34c8a4 100644
> > > --- a/arch/arm64/kernel/probes/kprobes.c
> > > +++ b/arch/arm64/kernel/probes/kprobes.c
> > > @@ -465,26 +465,30 @@ kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr)
> > >  	return DBG_HOOK_HANDLED;
> > >  }
> > >  
> > > -bool arch_within_kprobe_blacklist(unsigned long addr)
> > > +int __init arch_populate_kprobe_blacklist(void)
> > >  {
> > > -	if ((addr >= (unsigned long)__kprobes_text_start &&
> > > -	    addr < (unsigned long)__kprobes_text_end) ||
> > > -	    (addr >= (unsigned long)__entry_text_start &&
> > > -	    addr < (unsigned long)__entry_text_end) ||
> > > -	    (addr >= (unsigned long)__idmap_text_start &&
> > > -	    addr < (unsigned long)__idmap_text_end) ||
> > 
> > > -	    in_exception_text(addr))
> > 
> > You added this one in the previous patch, but it disappears here.
> 
> Yes, it is easy to explain how we transcribe from 
> arch_within_kprobe_blacklist() to arch_populate_kprobe_blacklist().
> 
> > 
> > 
> > > -		return true;
> > > -
> > > -	if (!is_kernel_in_hyp_mode()) {
> > > -		if ((addr >= (unsigned long)__hyp_text_start &&
> > > -		    addr < (unsigned long)__hyp_text_end) ||
> > > -		    (addr >= (unsigned long)__hyp_idmap_text_start &&
> > > -		    addr < (unsigned long)__hyp_idmap_text_end))
> > > -			return true;
> > > -	}
> > > -
> > > -	return false;
> > > +	int ret;
> > 
> > 
> > > +	ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
> > > +					(unsigned long)__kprobes_text_end);
> > > +	if (ret)
> > > +		return ret;
> > 
> > Now that we have arch_populate_kprobe_blacklist(), does the arch-code need to
> > blacklist the kprobes section itself?
> 
> Ah, good catch! No, we don't need it here. Sorry I worked on older patch.
> I'll update it.

Did you send a new version of this series? I can't seem to spot it in my
inbox.

Cheers,

Will