From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755242AbdCTO0X (ORCPT ); Mon, 20 Mar 2017 10:26:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37336 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755070AbdCTO0R (ORCPT ); Mon, 20 Mar 2017 10:26:17 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com B4B057FD46 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=jpoimboe@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com B4B057FD46 Date: Mon, 20 Mar 2017 09:02:17 -0500 From: Josh Poimboeuf To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Masami Hiramatsu , "H. Peter Anvin" , Andy Lutomirski , Linus Torvalds Subject: Re: [PATCH 5/6 v3] ftrace/x86_32: Add -mfentry support to x86_32 with DYNAMIC_FTRACE set Message-ID: <20170320140217.p27nu2hlx3e2p2kc@treble> References: <20170318210923.814509382@goodmis.org> <20170318211149.565075180@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170318211149.565075180@goodmis.org> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 20 Mar 2017 14:02:19 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Mar 18, 2017 at 05:09:28PM -0400, Steven Rostedt wrote: > From: "Steven Rostedt (VMware)" > > x86_64 has had fentry support for some time. I did not add support to x86_32 > as I was unsure if it will be used much in the future. It is still very much > used, and there's issues with function graph tracing with gcc playing around > with the mcount frames, causing function graph to panic. The fentry code > does not have this issue, and is able to cope as there is no frame to mess > up. > > Note, this only add support for fentry when DYNAMIC_FTRACE is set. There's > really no reason to not have that set, because the performance of the > machine drops significantly when it's not enabled. I only keep > !DYNAMIC_FTRACE around to test it off, as there's still some archs that have > FTRACE but not DYNAMIC_FTRACE. > > Reviewed-by: Masami Hiramatsu > Signed-off-by: Steven Rostedt (VMware) Reviewed-by: Josh Poimboeuf -- Josh