From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755447Ab3JaQSm (ORCPT ); Thu, 31 Oct 2013 12:18:42 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:51328 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754733Ab3JaQSl (ORCPT ); Thu, 31 Oct 2013 12:18:41 -0400 Date: Thu, 31 Oct 2013 16:18:26 +0000 From: Jamie Iles To: Steven Rostedt Cc: Jamie Iles , linux-kernel@vger.kernel.org Subject: Re: [PATCH] recordmcount.pl: add support for __fentry__ Message-ID: <20131031161826.GH29371@localhost> References: <1383235198-24961-1-git-send-email-jamie.iles@oracle.com> <20131031120926.112c3c26@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131031120926.112c3c26@gandalf.local.home> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 31, 2013 at 12:09:26PM -0400, Steven Rostedt wrote: > On Thu, 31 Oct 2013 15:59:58 +0000 > Jamie Iles wrote: > > > With gcc 4.6.0 the -mfentry feature places the function profiling call > > at the start of the function. When this is used, the call is to > > __fentry__ and not mcount. > > > > Based on 48bb5dc6cd9d30fe0d594947563da1f8bd9abada (ftrace: Make > > recordmcount.c handle __fentry__). > > Why? All current users of __fentry__ use the C version of recordmcount. > This just slows down the few archs that still use recordmcount.pl. Okay, it's probably fair to drop this one then if it's not useful to the other arches. We have a corner case with Ksplice where the C version of mcount not writing the section symbol for __mcount_loc causes a problem and we fall back to the perl version, but I'll spend some time working on fixing that instead. Thanks, Jamie