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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 12AA4C38A2A for ; Fri, 8 May 2020 10:12:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDC7020870 for ; Fri, 8 May 2020 10:12:33 +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="IALsoFlb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726817AbgEHKMd (ORCPT ); Fri, 8 May 2020 06:12:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36088 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725815AbgEHKMc (ORCPT ); Fri, 8 May 2020 06:12:32 -0400 Received: from merlin.infradead.org (unknown [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19C8AC05BD43 for ; Fri, 8 May 2020 03:12:32 -0700 (PDT) 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; bh=R9lBog4QwyyUN2dMY8gMVLm+VAmVFFjpkamhWWZmK+8=; b=IALsoFlbh7+AEmeiGBQPVqG+GV 5MPENByL3nWip53KQ4DnR7YepgNA5wA+QW8lHqy1NanzfGQB1jNBWIyVIpTCqJXLa1F9BPZY1GmQc iau3/5yltWKj8j+JAjfJkVg9DXwMhHgJqcas2VexN8f+3I9vtHwi8NjU0tn7hmUjZaHuqKZmGfwg7 4iTdMwOr0/Zg+fZYy7xG4wJGpbnOeyLbK/pajw7IbqwRAepurE3ai4Six1pKFCmzx/quVCT9I+fx5 p5oSJRNWJ1+valpWQKyzoTO7dR2DLYJXJKxDodc3YGlqpLe9FoJeQRQzXRLl7hfjSnXGc+yChgimt 7aok8oYQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWzzI-0006Ff-3a; Fri, 08 May 2020 10:12:12 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 67322301DFC; Fri, 8 May 2020 12:12:09 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 52997201C228D; Fri, 8 May 2020 12:12:09 +0200 (CEST) Date: Fri, 8 May 2020 12:12:09 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: Josh Poimboeuf , x86@kernel.org, linux-kernel@vger.kernel.org, luto@kernel.org Subject: Re: [RFC][PATCH 3/3] x86/entry, ORC: Teach objtool/unwind_orc about stack irq swizzles Message-ID: <20200508101209.GY5298@hirez.programming.kicks-ass.net> References: <20200507161020.783541450@infradead.org> <20200507161828.801097834@infradead.org> <20200507173809.GK5298@hirez.programming.kicks-ass.net> <20200507183048.rlf2bgj4cf2g4jy6@treble> <878si3e8v2.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <878si3e8v2.fsf@nanos.tec.linutronix.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 07, 2020 at 11:24:49PM +0200, Thomas Gleixner wrote: > But over our IRC conversation I came up with a 3rd variant: > > For most of the vectors the indirect call overhead is just noise, so > we can run them through the ASM switcher, but for the resched IPI > we can just use a separate direct call stub in ASM. Are we sure the rat-poison crap is noise for all the other system vectors? I suppose it is for most since they'll do indirect calls themselves anyway, right? > I can live with that. I might have to pay up for Peter's headaches to > teach objtool, but that's a different story. Let me check how many beers > he owes me first ... We're going to be so massively drunk if we ever settle that :-) For now I'll just have to live with knowing more about the unwinders.