linux-kernel - Re: [v5][PATCH] livepatch/ppc: Enable livepatching on powerpc

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Message-ID: <20160309172629.GB27913@lst.de>
Date:	Wed, 9 Mar 2016 18:26:29 +0100
From:	Torsten Duwe <duwe@....de>
To:	Petr Mladek <pmladek@...e.com>
Cc:	jeyu@...hat.com, jkosina@...e.cz, jikos@...nel.org,
	linux-kernel@...r.kernel.org, rostedt@...dmis.org,
	kamalesh@...ux.vnet.ibm.com, linuxppc-dev@...abs.org,
	live-patching@...r.kernel.org, mbenes@...e.cz
Subject: Re: [v5][PATCH] livepatch/ppc: Enable livepatching on powerpc

On Wed, Mar 09, 2016 at 05:10:25PM +0100, Petr Mladek wrote:
> On Tue 2016-03-08 16:34:35, Torsten Duwe wrote:
> > /* compile using "-ffixed-r14"! */
> > register unsigned long pass_TOC asm("r14");
> 
> BTW: Is this reentrant, please? I mean, is it possible to use this
> hack for two functions? Could the functions call each other?

Yes, it is. pass_TOC isn't really a global variable. It only lives
between the caller and the real function's return. With this notation
the task can easily be shifted to any other register.

	Torsten