linux-kernel - Re: [PATCH 2/2] Rewrite jump_label.c to use binary search

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Message-ID: <20100922150743.GA6272@Krystal>
Date:	Wed, 22 Sep 2010 11:07:43 -0400
From:	Mathieu Desnoyers <compudj@...stal.dyndns.org>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	jbaron@...hat.com, rusty@...tcorp.co.au, rostedt@...dmis.com,
	linux-kernel@...r.kernel.org, mingo@...e.hu, hpa@...or.com,
	tglx@...utronix.de, roland@...hat.com, rth@...hat.com,
	mhiramat@...hat.com, fweisbec@...il.com, avi@...hat.com,
	davem@...emloft.net, vgoyal@...hat.com, sam@...nborg.org,
	tony@...eyournoodle.com, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 2/2] Rewrite jump_label.c to use binary search

* Mathieu Desnoyers (mathieu.desnoyers@...ymtl.ca) wrote:
> * Andi Kleen (andi@...stfloor.org) wrote:
> > 
> > >
> > >>> +	for (; entry < stop && entry->key == key; entry++)
> > >>> +		if (kernel_text_address(entry->code))
> > >>
> > >> This does not work for modules I'm afraid, only for the core kernel. You
> > >> should test for __module_text_address() somewhere.
> > >
> > > I thought it was shared now, but ok.
> > 
> > Double checked. This is ok because kernel_text_address()
> > already checks for modules. You were probably thinking
> > of __kernel_text_address()
> 
> Ah right,
> 
> Although we have another problem:
> 
> __module_text_address() includes module init text, which defeats the
> purpose of the check put in there by Jason.
> 
> So the check works for the core kernel, but not for modules.

So, we have this issue, but I also have a question for Jason: what
happens if someone puts static jump in a function declared in the __init
section of the core kernel/module ? Can we enable them at early boot ?

Thanks,

Mathieu

> 
> Mathieu
> 
> > 
> > -Andi
> > 
> 
> -- 
> Mathieu Desnoyers
> Operating System Efficiency R&D Consultant
> EfficiOS Inc.
> http://www.efficios.com

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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