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Date: Thu, 25 Feb 2016 15:25:54 +0100
From: Torsten Duwe <duwe@lst.de>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@ozlabs.org, bsingharora@gmail.com,
 linux-kernel@vger.kernel.org, rostedt@goodmis.org,
 kamalesh@linux.vnet.ibm.com, pmladek@suse.com, jeyu@redhat.com,
 jkosina@suse.cz, live-patching@vger.kernel.org, mbenes@suse.cz
Subject: Re: [PATCH 08/12] powerpc/ftrace: Rework ftrace_caller()
Message-ID: <20160225142554.GI21932@lst.de>
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 <1456324115-21144-8-git-send-email-mpe@ellerman.id.au>
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On Thu, Feb 25, 2016 at 01:28:31AM +1100, Michael Ellerman wrote:
> The main change is to just use paca->kernel_toc, rather than a branch to
> +4 and mflr etc. That makes the code simpler and should also perform
> better.

Indeed.

> There was also a sequence after ftrace_call() where we load from
> pt_regs->nip, move to LR, then a few instructions later load from LRSAVE
> and move to LR. Instead I think we want to put pt_regs->nip into CTR and
> branch to it later.

Yes, I did some of this cleanup in the livepatch implementation.

> We also rework some of the SPR loads to hopefully speed them up a bit.
> Also comment the asm much more, to hopefully make it clearer.
> 
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Reviewed-by: Torsten Duwe <duwe@suse.de>

	Torsten