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Re: [PATCH -tip v3 00/23] kprobes: introduce NOKPROBE_SYMBOL() and general cleaning of kprobe blacklist
- From: Steven Rostedt <rostedt at goodmis dot org>
- To: "Frank Ch. Eigler" <fche at redhat dot com>
- Cc: Ingo Molnar <mingo at kernel dot org>, 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>, 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 12:56:49 -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> <20131120173600 dot GK8993 at redhat dot com>
On Wed, 20 Nov 2013 12:36:00 -0500
"Frank Ch. Eigler" <fche@redhat.com> wrote:
> 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
I'm curious to why one would do that. IIUC, perf now has function
tracing support.
-- Steve
>
> 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