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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0771BC433EF for ; Wed, 2 Mar 2022 00:54:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=liI/5Edjo/uRtYpAHpLM/tJB5SrDlM3HAEKrL1U7jNk=; b=JOF6UL+LY8snIA xxAswqZfpHuTGH9TGcf73Wo/GxyeTC2DXD9T3iox+7WOVITyATuRAcvpGH92tRL0HzNUCuF8+Qfuu 8gssDrHEBxohldXLAW88JncThozn7JP/04PUHWvaI7Alh3WlMFpSeZ4t+8/t2kUNn7V7lu7xoLoXW RdZxN8l3K/lTF2nh/NmS/4/hc+j611wqy/F70+pFJgVpR6MadCSMYgpRhotF8nrRTEt0S3wn+G9On lkaQo92R2wAJA+Cx0aydOE2PgFLw+yvDy7gtyNIP3mqQt2cobzo61dLgk7QQRGm3arUkVWZk95QEw 2HErSM4vgcs7Pjoe4X9g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPDE7-000vyE-1R; Wed, 02 Mar 2022 00:52:23 +0000 Received: from mail-pj1-x1035.google.com ([2607:f8b0:4864:20::1035]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nPDE1-000vx8-Kb for linux-arm-kernel@lists.infradead.org; Wed, 02 Mar 2022 00:52:21 +0000 Received: by mail-pj1-x1035.google.com with SMTP id v4so375882pjh.2 for ; Tue, 01 Mar 2022 16:52:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=HC3ZptybfOrcN0FwSYcdw8efvW/w5BuLTG20h69vWy8=; b=BbvfalDRv4VSuNAjwEQPYgeQv+916qvcYdEI0rhrqHnf4zJx6dUovakTISCl2o3pBh AMHb/aUrzKnoiXOB46bSdDmHdgK8AHz+Q5TaN+e5ryW4m2eZYG2VqlD8nyn0+944JjCx JccuGRDpu7NubLNEYyyMPM9/A3Sd/SuLbVIIibeQVmfmkBox0qKPQe9IpYncWFFbu67Z HRkmfXv/AU5xDm4oXTLeiimsNAXWH5iU+nnIhjpJ0oTb74yfP3vFHlOQrVn3wHS3QXPl cXUzwjBeOAo4UEkIWhEWBY8oH7knZnsh0vOcxescMX/9mnEHEw7fD+k/ieWPzLgcObAK X63w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=HC3ZptybfOrcN0FwSYcdw8efvW/w5BuLTG20h69vWy8=; b=ylHXTZirs3ciSuLunFo9MPy4Z0bO5C4enLT55BIxtzUQy674e7eJ2mMiGF9vSTAGch ZybotusvJUvVZsGQLu+RPR6iSZv4GvsibJLji52GzEbMEzDMLYP56PqFg9TxFsePnylh mM5P+aXpG5K+lS714ROJR2L/cyAawwbdhh4kqtQ7aNPASBbrrYIaUIQZQ4TOn6pizXnR EmDSF6b50qhaeD4DBppWnOYDZDIgkMTOzExPm+lnvnjcVoDOdKtIQIE7owkNAIKQYkyX /0o/nl/rrEaqqBay3PpMKkhXZrnTIwaIowvOUeWv4+DCHEz4twjPzbf/FIb53Yd9yV4N 2wbA== X-Gm-Message-State: AOAM5310z4JBWT+Z9fICcFEMGJD7+FiRicNYqbtADcqKnSYTHiFOqJmR 6Yx6D7KaQRdp9XTeA70Xrb0wjw== X-Google-Smtp-Source: ABdhPJyhoDEh3lherEvVt9LfMK0mrUIsb7RM5Q+XH20QBTkHDgwcARTsU4qjqLtUk9BRQiN2Qn/dDA== X-Received: by 2002:a17:90a:d90b:b0:1bc:4ec7:d867 with SMTP id c11-20020a17090ad90b00b001bc4ec7d867mr24502469pjv.226.1646182326690; Tue, 01 Mar 2022 16:52:06 -0800 (PST) Received: from google.com ([2620:15c:2ce:200:edd8:170c:efd5:6a92]) by smtp.gmail.com with ESMTPSA id s17-20020a17090a441100b001bc1b59fe1asm3061268pjg.38.2022.03.01.16.52.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Mar 2022 16:52:06 -0800 (PST) Date: Tue, 1 Mar 2022 16:52:01 -0800 From: Evgenii Stepanov To: Mark Brown Cc: Catalin Marinas , Will Deacon , Joey Gouly , Branislav Rankov , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v1 4/4] arm64/mte: Add userspace interface for enabling asymmetric mode Message-ID: References: <20220127195712.748150-1-broonie@kernel.org> <20220127195712.748150-5-broonie@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220127195712.748150-5-broonie@kernel.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220301_165217_715201_080CF4C3 X-CRM114-Status: GOOD ( 13.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jan 27, 2022 at 07:57:12PM +0000, Mark Brown wrote: > Since there PR_MTE_TCF_ values are a bitmask (allowing the kernel to choose > between the multiple modes) and there are no free bits adjacent to the > existing PR_MTE_TCF_ bits the set of bits used to specify the mode becomes > disjoint. Programs using the new interface should be aware of this and > programs that do not use it will not see any change in behaviour. Extending PR_MTE_TCF_MASK seems bad for backward compatibility. User code may do "flags =& ~PR_MTE_TCF_MASK" to disable MTE; when compiled against an old version of the header this would fail to remove the ASYMM bit. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel