From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752975AbcBOWVP (ORCPT ); Mon, 15 Feb 2016 17:21:15 -0500 Received: from verein.lst.de ([213.95.11.211]:34401 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751338AbcBOWVN (ORCPT ); Mon, 15 Feb 2016 17:21:13 -0500 Date: Mon, 15 Feb 2016 23:21:11 +0100 From: Torsten Duwe To: Michael Ellerman Cc: Balbir Singh , Jiri Kosina , Miroslav Benes , Petr Mladek , Jessica Yu , Steven Rostedt , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Subject: Re: [PATCH v8 4/8] ppc64 ftrace_with_regs configuration variables Message-ID: <20160215222111.GA3321@lst.de> References: <20160210174221.EBBEC692C8@newverein.lst.de> <20160210174450.9C065692C8@newverein.lst.de> <1455176897.2885.12.camel@gmail.com> <20160211084230.GB29683@lst.de> <1455532035.26205.5.camel@ellerman.id.au> <20160215140408.GA22872@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160215140408.GA22872@lst.de> 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 Mon, Feb 15, 2016 at 03:04:08PM +0100, Torsten Duwe wrote: > If you use "-pg -mprofile-kernel", gcc seems to forget that, and omits the TOC > load, for a similar assembler calling sequence. > > Looking at the code I can _understand_ why this is so, but my GCC knowledge > is not that deep that I could easily _fix_ this reliably. Nonetheless, here's a proposal. --- a/gcc/config/rs6000/rs6000.c +++ b/gcc/config/rs6000/rs6000.c @@ -25154,6 +25154,10 @@ rs6000_emit_prologue (void) { cfun->machine->r2_setup_needed = df_regs_ever_live_p (TOC_REGNUM); + /* Profiling _will_ generate a call to a global _mcount. */ + if (crtl->profile) + cfun->machine->r2_setup_needed = true; + /* With -mminimal-toc we may generate an extra use of r2 below. */ if (TARGET_TOC && TARGET_MINIMAL_TOC && get_pool_size () != 0) cfun->machine->r2_setup_needed = true;