linux-kernel - Re: [PATCH] [2/11] x86: Fix alternatives and kprobes to remap write-protected kernel text

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Message-ID: <20070723152542.GA13457@Krystal>
Date:	Mon, 23 Jul 2007 11:25:42 -0400
From:	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>
To:	Andi Kleen <ak@...e.de>
Cc:	jbeulich@...ell.com, jeremy@...p.org, zach@...are.com,
	patches@...-64.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [2/11] x86: Fix alternatives and kprobes to remap write-protected kernel text

* Andi Kleen (ak@...e.de) wrote:
> On Monday 23 July 2007 16:46:03 Mathieu Desnoyers wrote:
> 
> > I would recommend to prefix with __init every function that is assumed
> > "safe" because executed at boot time. It would minimize the risks of
> > buggy usage of these text-modification primitives. That includes
> > text_poke() and a big chunk of the apply alternative code. (it should
> > never be executed on a live system, except at boot time, right ?)
> 
> lock prefix patching can happen later on cpu hotplug/unplug event.
> 

There seem to be a separate set of functions for applying smp lock
prefixes and more "general" alternatives. I guess the "general"
alternatives and paravirt could be declared __init, and text_poke users
would have to use it responsibly. Such as:

__init apply_alternatives
__init apply_paravirt

non init:
alternatives_smp_*
alternatives_smp_

Mathieu

> -Andi
> 

-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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