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=-2.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 36F44C004C9 for ; Tue, 7 May 2019 16:35:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01547205C9 for ; Tue, 7 May 2019 16:35:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZlA04PGR" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726754AbfEGQfZ (ORCPT ); Tue, 7 May 2019 12:35:25 -0400 Received: from merlin.infradead.org ([205.233.59.134]:40306 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726197AbfEGQfY (ORCPT ); Tue, 7 May 2019 12:35:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=OwZTZ1ye0D7Ag0dmc5Qr6LUWP6U5n+yawypfjqqzLy4=; b=ZlA04PGR8vVdeot8a14D0ychS eWlNjZpfHpgXS1NucZeTFXBN6jJkNeLPtBeU8nc6mOgBgLRA1xaPZuwO3hTJ77EaFcmQFRWUBCeqP pO44MV2/RaY16zho2uINk0qCw4dSVUhH10mHw3LlTxvGNWIJ52/B93mC630NkcbkEWz4NZtDvSoY6 dXyLN3Nt8Adquvr7tqbkZzVGmNW9CrqxJ+5NkPrpdKvDDW3jx9uFyc5VIRe/3NoO8SWwXSOAaaS/1 M6ADRbzJItWnPrqpwVoIpbeAlzU/AHKAqtcQkPYt/aIoQVcTZy6A4Rk3O551zLBoYmjkiO2TyskkC miJyDezIw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hO33D-0001Qi-BY; Tue, 07 May 2019 16:34:43 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C52CC20F40185; Tue, 7 May 2019 18:34:40 +0200 (CEST) Date: Tue, 7 May 2019 18:34:40 +0200 From: Peter Zijlstra To: Linus Torvalds Cc: Steven Rostedt , Andy Lutomirski , Linux List Kernel Mailing , Ingo Molnar , Andrew Morton , Andy Lutomirski , Nicolai Stange , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , the arch/x86 maintainers , Josh Poimboeuf , Jiri Kosina , Miroslav Benes , Petr Mladek , Joe Lawrence , Shuah Khan , Konrad Rzeszutek Wilk , Tim Chen , Sebastian Andrzej Siewior , Mimi Zohar , Juergen Gross , Nick Desaulniers , Nayna Jain , Masahiro Yamada , Joerg Roedel , "open list:KERNEL SELFTEST FRAMEWORK" , stable , Masami Hiramatsu Subject: Re: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions Message-ID: <20190507163440.GV2606@hirez.programming.kicks-ass.net> References: <20190506215353.14a8ef78@oasis.local.home> <20190506225819.11756974@oasis.local.home> <20190506232158.13c9123b@oasis.local.home> <20190507111227.1d4268d7@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 07, 2019 at 08:31:14AM -0700, Linus Torvalds wrote: > The reality is that changing something fundamental like the kernel > stack at this point for an architecture that will not change in the > future is silly. In my eyes it makes sense because i386 is a minority architecture at this point, and 'nobody' wants to care about how its different if they don't have to. > The reality is that Peter's patch is much bigger than mine, because it > needed a lot of other changes *because* it did that change. Yes, I change the way stack layout works on i386, and yes that affects a lot of code. _However_ all of that code is now more like x86_64 than it was. Earlier you said that kernel_stack_pointer() was a horrible thing; and most/all the code that I ended up touching was similarly horrible. Would you consider my approach later on, under the guise of unification? We can work on it for a while, and make sure all the iffy bits are sorted, no need to rush? From mboxrd@z Thu Jan 1 00:00:00 1970 From: peterz at infradead.org (Peter Zijlstra) Date: Tue, 7 May 2019 18:34:40 +0200 Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions In-Reply-To: References: <20190506215353.14a8ef78@oasis.local.home> <20190506225819.11756974@oasis.local.home> <20190506232158.13c9123b@oasis.local.home> <20190507111227.1d4268d7@gandalf.local.home> Message-ID: <20190507163440.GV2606@hirez.programming.kicks-ass.net> On Tue, May 07, 2019 at 08:31:14AM -0700, Linus Torvalds wrote: > The reality is that changing something fundamental like the kernel > stack at this point for an architecture that will not change in the > future is silly. In my eyes it makes sense because i386 is a minority architecture at this point, and 'nobody' wants to care about how its different if they don't have to. > The reality is that Peter's patch is much bigger than mine, because it > needed a lot of other changes *because* it did that change. Yes, I change the way stack layout works on i386, and yes that affects a lot of code. _However_ all of that code is now more like x86_64 than it was. Earlier you said that kernel_stack_pointer() was a horrible thing; and most/all the code that I ended up touching was similarly horrible. Would you consider my approach later on, under the guise of unification? We can work on it for a while, and make sure all the iffy bits are sorted, no need to rush? From mboxrd@z Thu Jan 1 00:00:00 1970 From: peterz@infradead.org (Peter Zijlstra) Date: Tue, 7 May 2019 18:34:40 +0200 Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions In-Reply-To: References: <20190506215353.14a8ef78@oasis.local.home> <20190506225819.11756974@oasis.local.home> <20190506232158.13c9123b@oasis.local.home> <20190507111227.1d4268d7@gandalf.local.home> Message-ID: <20190507163440.GV2606@hirez.programming.kicks-ass.net> Content-Type: text/plain; charset="UTF-8" Message-ID: <20190507163440.V7r8qpIqYit7Q_kyfg6NVsr48U65P5dfxFAFV9362GQ@z> On Tue, May 07, 2019@08:31:14AM -0700, Linus Torvalds wrote: > The reality is that changing something fundamental like the kernel > stack at this point for an architecture that will not change in the > future is silly. In my eyes it makes sense because i386 is a minority architecture at this point, and 'nobody' wants to care about how its different if they don't have to. > The reality is that Peter's patch is much bigger than mine, because it > needed a lot of other changes *because* it did that change. Yes, I change the way stack layout works on i386, and yes that affects a lot of code. _However_ all of that code is now more like x86_64 than it was. Earlier you said that kernel_stack_pointer() was a horrible thing; and most/all the code that I ended up touching was similarly horrible. Would you consider my approach later on, under the guise of unification? We can work on it for a while, and make sure all the iffy bits are sorted, no need to rush?