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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 34ADBC388F9 for ; Wed, 11 Nov 2020 20:39:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 95351208B8 for ; Wed, 11 Nov 2020 20:39:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ZvdQIxRD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726611AbgKKUjt (ORCPT ); Wed, 11 Nov 2020 15:39:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35516 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725900AbgKKUjt (ORCPT ); Wed, 11 Nov 2020 15:39:49 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 239E6C0613D1 for ; Wed, 11 Nov 2020 12:39:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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=+xuKYc0X+UN/uYD5LNznUOLcd4BbelJ9pcfJxobTWf8=; b=ZvdQIxRDcDVreTfUZpwVhiNEFJ 5qV1CT9de2hFKXm2ckHMZPEMyzTF759KfYhLLhiV6bNgXNB3DUGZivkBzvTwrBA+jLZ5LsCkdV7/X kRfq3QuKvbRDzyf7li86dLmFrwI2bRbIBRluJdPaUVkKH7rWMLpLxXdDOBirSSVbrECTdYBis9fmh UrSjuWg/lLvHgvrZn8GAOeQ7fIhZ71AHFgQIo0EBDn/LNP6IIEmL2oR/U3YLzCDb7GlorOuaUxL0V Yvbzb6YZbX9MHqr7rDs6DTx1N8Ot+0kDbCAcRaLKT79VInE/7ppSxeu6G4DBckyLL5oCaXnrnimAF 93zdWtRg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kcwu6-0007yl-B6; Wed, 11 Nov 2020 20:39:42 +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 DB4C3301EE3; Wed, 11 Nov 2020 21:39:41 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C78CD2BCE964C; Wed, 11 Nov 2020 21:39:41 +0100 (CET) Date: Wed, 11 Nov 2020 21:39:41 +0100 From: Peter Zijlstra To: Andrew Cooper Cc: Josh Poimboeuf , Shinichiro Kawasaki , "linux-kernel@vger.kernel.org" , Nicholas Piggin , Damien Le Moal , jgross@suse.com, x86@kernel.org Subject: Re: WARNING: can't access registers at asm_common_interrupt Message-ID: <20201111203941.GP2628@hirez.programming.kicks-ass.net> References: <20201106060414.edtcb7nrbzm4a32t@shindev.dhcp.fujisawa.hgst.com> <20201111170536.arx2zbn4ngvjoov7@treble> <20201111174736.GH2628@hirez.programming.kicks-ass.net> <20201111181328.mbxcz2uap2vnqpxq@treble> <33843b7f-ed8a-8fcb-19bc-c76cf00f453d@citrix.com> <20201111194206.GK2628@hirez.programming.kicks-ass.net> <20201111195900.2x7kfce2ejkmrzi3@treble> <20201111200730.GM2628@hirez.programming.kicks-ass.net> <20201111201506.bftpmx4svxn376tn@treble> <61b2538f-7be6-8f4a-9395-03071b5cc6f0@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <61b2538f-7be6-8f4a-9395-03071b5cc6f0@citrix.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 11, 2020 at 08:25:36PM +0000, Andrew Cooper wrote: > > Right, it makes objtool's job a _little_ easier, since it already knows > > how to read alternatives. But it still has to learn to deal with the > > conflicting stack layouts. > > I suppose the needed abstraction is "these blocks will start and end > with the same stack layout", while allowing the internals to diverge. It's a little more complicated than that due to the fact that there is only a single ORC table. So something like: alt0 alt1 0x00 push 0x00 nop 0x01 nop 0x01 push is impossible to correctly unwind.