From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760819AbcBYOZ6 (ORCPT ); Thu, 25 Feb 2016 09:25:58 -0500 Received: from verein.lst.de ([213.95.11.211]:48599 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760085AbcBYOZ4 (ORCPT ); Thu, 25 Feb 2016 09:25:56 -0500 Date: Thu, 25 Feb 2016 15:25:54 +0100 From: Torsten Duwe To: Michael Ellerman 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> References: <1456324115-21144-1-git-send-email-mpe@ellerman.id.au> <1456324115-21144-8-git-send-email-mpe@ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1456324115-21144-8-git-send-email-mpe@ellerman.id.au> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Reviewed-by: Torsten Duwe Torsten