From mboxrd@z Thu Jan 1 00:00:00 1970 From: Catalin Marinas Subject: Re: [PATCH v4 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt Date: Thu, 13 Jun 2019 13:28:21 +0100 Message-ID: <20190613122821.GS28951@C02TF0J2HF1T.local> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20190613113731.GY28398@e103592.cambridge.arm.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org To: Dave Martin 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 List-Id: linux-arch.vger.kernel.org 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. -- Catalin From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com ([217.140.110.172]:39168 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731876AbfFMM2j (ORCPT ); Thu, 13 Jun 2019 08:28:39 -0400 Date: Thu, 13 Jun 2019 13:28:21 +0100 From: Catalin Marinas Subject: Re: [PATCH v4 1/2] arm64: Define Documentation/arm64/tagged-address-abi.txt Message-ID: <20190613122821.GS28951@C02TF0J2HF1T.local> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190613113731.GY28398@e103592.cambridge.arm.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dave Martin Cc: Vincenzo Frascino , 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, linux-arm-kernel@lists.infradead.org Message-ID: <20190613122821.q3zHbteOb1hK96sRPRT-sFy9IgS9U6G4TFdCieFHqsg@z> 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. -- Catalin