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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 20873C43219 for ; Tue, 15 Nov 2022 19:38:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230245AbiKOTim (ORCPT ); Tue, 15 Nov 2022 14:38:42 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40810 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229642AbiKOTij (ORCPT ); Tue, 15 Nov 2022 14:38:39 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ACF2EDE8D for ; Tue, 15 Nov 2022 11:38:37 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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=YjA/Ad/XxCVAlWu1iPIeT3IVaSA8C09QDHCG8r7fee0=; b=XjA7TarsVxzV99sbuNHH8kY/A7 iG24UfHkxnZnkKHbHyGB8C1Kng1egEKviH4iKiRXW5lSjrJxFMKZ69/hosSY4Zy++gBE/AFCJdhSy kuYSmsrlWpx5Cj84lO/wkVh20MTxtbKP8KMadWr3TPfq1Y+f9dDfmPyZU7G4mnPKlIun2Zv8koUPX 96k9XuXameTjMqOCdz2emhRsIReUHYNLffZBm9zJx2eaefVe8dIbE660V5hBIOrNCJmOUT27UgMXF v5n+axW3SPk1a1maD5p3m/Hh8SKvspIFWAd4UY5s2/8OCiGLjqvTaV9Wfk4EgpmJySStq+9KMJQx1 y4rO7t5A==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1ov1lM-0015NK-Vv; Tue, 15 Nov 2022 19:38:29 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 9AE6B30115B; Tue, 15 Nov 2022 19:45:03 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 859EB20C99E5C; Tue, 15 Nov 2022 19:45:03 +0100 (CET) Date: Tue, 15 Nov 2022 19:45:03 +0100 From: Peter Zijlstra To: "Edgecombe, Rick P" Cc: "Torvalds, Linus" , "keescook@chromium.org" , "linux-kernel@vger.kernel.org" , "fweimer@redhat.com" , "hjl.tools@gmail.com" , "x86@kernel.org" Subject: Re: CET shadow stack app compatibility Message-ID: References: <7d8133c7e0186bdaeb3893c1c808148dc0d11945.camel@intel.com> <883ed1a3f4de8d508c4bc2f504ae4a5c8db19a20.camel@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <883ed1a3f4de8d508c4bc2f504ae4a5c8db19a20.camel@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 15, 2022 at 05:04:40PM +0000, Edgecombe, Rick P wrote: > > ELF bits should not, must not, be called CET. API, not CET, Compiler > > features, also not CET. > > So the arch_prctl()s can't be shared between shadow stack and IBT? They > don't have to be, but this is a new thing after a fair amount of > earlier discussion. I would very strongly suggest IBT not use that interface and instead we follow ARM64 BTI's lead -- such that application developers don't go insane trying to use two nearly identical solutions. I mean, the toolchain folks made a godawefull mess of things, but we don't have to.