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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 C5CB2C31E45 for ; Thu, 13 Jun 2019 13:23:52 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 9ADBC2173C for ; Thu, 13 Jun 2019 13:23:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="W/sGmmvy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9ADBC2173C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=5Nstq3gJ8vRO83fsxpGQF8VkySepRcEfz/CTdsD4haw=; b=W/sGmmvy+VF8En y3acgiOeqb2jOKGq8TqoTJR3YhPZqWNveo9vSa86UnlwvRi6g8WQIFzaxgWFi57IZBn8vEeZMsaUH M9Ue9cb115vZqa8zR3A+HM3oblR76wz75TapIY1xDiCqal0OdQwwvTn+QS0ScA/5W12C6QF61he9T PazyTzWEliWzg/aEq0w68elHq/0k9DUyEY6HwI9XhVWztOKEGysnB0+GNtn+81TkLmUm/Dr0j0tJk ulw/nQsubMBRXgbwXKvlK/0ktGLvumXpDO9IEGmE/XX2VxPgKLH/LeSA2OBnnZTAHNO5+KEN4/H6w PB/p6ecf4Luvi9zlytaw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hbPhn-0001Rp-CC; Thu, 13 Jun 2019 13:23:51 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hbPhk-0001RP-9Q for linux-arm-kernel@lists.infradead.org; Thu, 13 Jun 2019 13:23:49 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3E6A63EF; Thu, 13 Jun 2019 06:23:47 -0700 (PDT) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A51833F73C; Thu, 13 Jun 2019 06:23:45 -0700 (PDT) Date: Thu, 13 Jun 2019 14:23:43 +0100 From: Dave Martin To: Catalin Marinas Subject: Re: [PATCH v4 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt Message-ID: <20190613132342.GZ28398@e103592.cambridge.arm.com> References: <20190612142111.28161-1-vincenzo.frascino@arm.com> <20190612142111.28161-2-vincenzo.frascino@arm.com> <20190612153538.GL28951@C02TF0J2HF1T.local> <141c740a-94c2-2243-b6d1-b44ffee43791@arm.com> <20190613113731.GY28398@e103592.cambridge.arm.com> <20190613122821.GS28951@C02TF0J2HF1T.local> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190613122821.GS28951@C02TF0J2HF1T.local> User-Agent: Mutt/1.5.23 (2014-03-12) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190613_062348_369649_1D94823D X-CRM114-Status: GOOD ( 15.91 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, Szabolcs Nagy , Andrey Konovalov , Will Deacon , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Alexander Viro , linux-kselftest@vger.kernel.org, Vincenzo Frascino , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jun 13, 2019 at 01:28:21PM +0100, Catalin Marinas wrote: > On Thu, Jun 13, 2019 at 12:37:32PM +0100, Dave P Martin wrote: > > On Thu, Jun 13, 2019 at 11:15:34AM +0100, Vincenzo Frascino wrote: > > > On 12/06/2019 16:35, Catalin Marinas wrote: > > > > On Wed, Jun 12, 2019 at 03:21:10PM +0100, Vincenzo Frascino wrote: > > > >> + - PR_GET_TAGGED_ADDR_CTRL: can be used to check the status of the Tagged > > > >> + Address ABI. > [...] > > Is there a canonical way to detect whether this whole API/ABI is > > available? (i.e., try to call this prctl / check for an HWCAP bit, > > etc.) > > The canonical way is a prctl() call. HWCAP doesn't make sense since it's > not a hardware feature. If you really want a different way of detecting > this (which I don't think it's worth), we can reinstate the AT_FLAGS > bit. Sure, I think this probably makes sense -- I'm still getting my around which parts of the design are directly related to MTE and which aren't. I was a bit concerned about the interaction between PR_SET_TAGGED_ADDR_CTRL and the sysctl: the caller might conclude that this API is unavailable when actually tagged addresses are stuck on. I'm not sure whether this matters, but it's a bit weird. One option would be to change the semantics, so that the sysctl just forbids turning tagging from off to on. Alternatively, we could return a different error code to distinguish this case. Or we just leave it as proposed. Cheers ---Dave _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel