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Re: [PATCH -tip v3 00/23] kprobes: introduce NOKPROBE_SYMBOL() and general cleaning of kprobe blacklist
- From: "Frank Ch. Eigler" <fche at redhat dot com>
- To: Ingo Molnar <mingo at kernel dot org>
- Cc: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>, linux-arch at vger dot kernel dot org, Ananth N Mavinakayanahalli <ananth at in dot ibm dot com>, Sandeepa Prabhu <sandeepa dot prabhu at linaro dot org>, x86 at kernel dot org, lkml <linux-kernel at vger dot kernel dot org>, "Steven Rostedt (Red Hat)" <rostedt at goodmis dot org>, virtualization at lists dot linux-foundation dot org, systemtap at sourceware dot org, "David S. Miller" <davem at davemloft dot net>
- Date: Wed, 20 Nov 2013 12:36:00 -0500
- Subject: Re: [PATCH -tip v3 00/23] kprobes: introduce NOKPROBE_SYMBOL() and general cleaning of kprobe blacklist
- Authentication-results: sourceware.org; auth=none
- References: <20131120042148 dot 15296 dot 88360 dot stgit at kbuild-fedora dot novalocal> <y0mvbznxi6k dot fsf at fche dot csb> <20131120153801 dot GA9743 at gmail dot com>
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