linux-kernel - Re: [PATCH -tip v3 00/23] kprobes: introduce NOKPROBE_SYMBOL() and general cleaning of kprobe blacklist

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Message-ID: <20131120173600.GK8993@redhat.com>
Date:	Wed, 20 Nov 2013 12:36:00 -0500
From:	"Frank Ch. Eigler" <fche@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	linux-arch@...r.kernel.org,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Sandeepa Prabhu <sandeepa.prabhu@...aro.org>, x86@...nel.org,
	lkml <linux-kernel@...r.kernel.org>,
	"Steven Rostedt (Red Hat)" <rostedt@...dmis.org>,
	virtualization@...ts.linux-foundation.org,
	systemtap@...rceware.org, "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH -tip v3 00/23] kprobes: introduce NOKPROBE_SYMBOL() and general cleaning of kprobe blacklist

Hi -

> > Does this new blacklist cover enough that the kernel now survives a 
> > broadly wildcarded perf-probe, e.g. over e.g. all of its kallsyms?
> 
> That's generally the purpose of the annotations - if it doesn't then 
> that's a bug.

AFAIK, no kernel since kprobes was introduced has ever stood up to
that test.  perf probe lacks the wildcarding powers of systemtap, so
one needs to resort to something like:

# cat /proc/kallsyms | grep ' [tT] ' | while read addr type symbol; do
   perf probe $symbol
done

then wait for a few hours for that to finish. Then, or while the loop
is still running, run

# perf record -e 'probe:*' -aR sleep 1

to take a kernel down.


- FChE
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