From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2230ECE58C for ; Mon, 7 Oct 2019 15:08:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D201B21479 for ; Mon, 7 Oct 2019 15:08:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729074AbfJGPII (ORCPT ); Mon, 7 Oct 2019 11:08:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:34038 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729050AbfJGPIH (ORCPT ); Mon, 7 Oct 2019 11:08:07 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D3D692070B; Mon, 7 Oct 2019 15:08:05 +0000 (UTC) Date: Mon, 7 Oct 2019 11:08:04 -0400 From: Steven Rostedt To: Ingo Molnar Cc: Peter Zijlstra , x86@kernel.org, linux-kernel@vger.kernel.org, mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com, torvalds@linux-foundation.org, tglx@linutronix.de, namit@vmware.com, hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org, jpoimboe@redhat.com, hjl.tools@gmail.com Subject: Re: [RFC][PATCH 0/9] Variable size jump_label support Message-ID: <20191007110804.66edaa03@gandalf.local.home> In-Reply-To: <20191007125519.GA56546@gmail.com> References: <20191007090225.44108711.6@infradead.org> <20191007084443.79370128.1@infradead.org> <20191007120756.GE2311@hirez.programming.kicks-ass.net> <20191007125519.GA56546@gmail.com> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 7 Oct 2019 14:55:19 +0200 Ingo Molnar wrote: > * Peter Zijlstra wrote: > > > IIRC the recordmcount variant from Steve was also rewriting JMP8 to NOP2 > > at build time. > > > > I dug this here link out of my IRC logs: > > > > https://lore.kernel.org/lkml/1318007374.4729.58.camel@gandalf.stny.rr.com/ > > Ancient indeed ... > > > Looking at that, part of the reason might've been running yet another > > tool, instead of having one tool do everything. > > Yeah - that too wouldn't be a problem with objtool, as we are running it > anyway, right? > > So I can see about 2 valid technical reasons why Linus would have > objected to that old approach from Steve while finding the objtool > approach more acceptable. > > Basically the main assumption is that we better never run out of > competent objtool experts... :-) Actually, even back then I said that it would be best to merge all the tools into one (I just didn't have the time to implement it), and then we could pull this off. I have one of my developers working to merge record-mcount into objtool now (there's been some patches floating around). Then with a single tool, it shouldn't be controversial. -- Steve