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Message-ID: <20090924150333.GA26389@Krystal>
Date: Thu, 24 Sep 2009 11:03:33 -0400
From: Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org,
"Frank Ch. Eigler" <fche@...hat.com>,
Hideo AOKI <haoki@...hat.com>,
Takashi Nishiie <t-nishiie@...css.fujitsu.com>,
Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...hat.com>
Subject: Re: [patch 12/12] Tracepoints - Immediate Values
* Peter Zijlstra (peterz@...radead.org) wrote:
> On Thu, 2009-09-24 at 09:26 -0400, Mathieu Desnoyers wrote:
> > plain text document attachment (tracepoints-immediate-values.patch)
> > Use immediate values in tracepoints.
>
> I might have missed it, but did both the Intel and AMD cpu folks clear
> the SMP code rewrite bits?
>
SMP handling is performed with stop_machine() in this patchset. Nothing
fancy here.
I've got other patches, not included in this patchset, which implements
nmi-safe code modification, based on a scheme using breakpoints and
IPIs, inspired from djprobes. That one might be worth clearing with
intel/amd devs before merging.
However, doing code patching within stop_machine() is pretty safe, given
all other CPUs are busy-looping with interrupts off while this happens.
Ftrace already does this.
Thanks,
Mathieu
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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