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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 4BD87C433DB for ; Wed, 10 Feb 2021 17:16:43 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (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 EDF2264DE9 for ; Wed, 10 Feb 2021 17:16:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDF2264DE9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=merlin.20170209; h=Sender: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-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=C/37xKGYSoS4rmYuaFH4mwkMuCqKNqqGcmze/Ngn6UE=; b=RcZp3xL+wkY8iy6qMmrC2m01Y M01WAWnXgm/X+z+Lipsh28q0LZTIX+Cqs32bi3W3DXs30OrhJmt4VFN1eoPgVsnUqMme2PJGgYXnU VjK3EW9oqdC128634WV2c+ZTvVrqhELP5xgEqE7yoA3sOYZKpVbVqdL9hgK9q1n3dpB2bnHQLcZKm NR9J8XgWZTyCjYpslMfny47OUenCm2LVJYc4K5iUjQDKJ4cJq/vW2mCwiD6Vss2hXYEFmoflze8WC 2IMpffGbAVLA2Dra3F7SUxiKPGHp+XgQk6UMt/+jn9qEOdPe415aDkVwIksxtgAFhqW8bKW1zdwb3 qjehDpXtw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1l9t5Y-0007Sa-Cw; Wed, 10 Feb 2021 17:15:40 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1l9t5V-0007RR-8U for linux-arm-kernel@lists.infradead.org; Wed, 10 Feb 2021 17:15:38 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 78F3E64DE8; Wed, 10 Feb 2021 17:15:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1612977336; bh=6fenlg+SCsaYGlajDXZ7/yNeO+1PnQNd98rvcz7rb04=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=OI2OaGkRkBZ1O8d/CBvahMOqFfVrPGW3EI1ciPd/5ekVUgxahDRZkUbNHjTMkg4tP MU/e9LXA9YsZF3ZJRk9cgJ1emR5z6C0oVHHP4cvNuQkC9zo011hKEe7/kWkx0Y3sR1 qmBJ1EDRBIiCa9dPJvDlypk9gu+McEFEPKE/tXJ35i9Zas+F27wKgDB2WeQ04Sxb1D cz1UKLGMq9/EcT1zJSuJNdFUEp58zFruxdPKQai0Xhj27xN166OjYuk6EX+BxZFvsj JctzXhvhtLfaxAFArDka06EObcPIsHUV9GUOoGwEiELBu5jkbjuQoRgH9uGJ+1rqPK qOe6WnTi+XtDw== Date: Wed, 10 Feb 2021 17:14:42 +0000 From: Mark Brown To: Dave Martin Subject: Re: [PATCH v7 1/2] arm64/sve: Split TIF_SVE into separate execute and register state flags Message-ID: <20210210171442.GC4748@sirena.org.uk> References: <20210201122901.11331-1-broonie@kernel.org> <20210201122901.11331-2-broonie@kernel.org> <20210210105650.GI21837@arm.com> <20210210145452.GA4748@sirena.org.uk> <20210210154249.GK21837@arm.com> MIME-Version: 1.0 In-Reply-To: <20210210154249.GK21837@arm.com> X-Cookie: Are we live or on tape? User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210210_121537_461583_F5144BF1 X-CRM114-Status: GOOD ( 24.21 ) 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: Julien Grall , Julien Grall , Catalin Marinas , Zhang Lei , Will Deacon , linux-arm-kernel@lists.infradead.org, Daniel Kiss Content-Type: multipart/mixed; boundary="===============1938726939502056056==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============1938726939502056056== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="FsscpQKzF/jJk6ya" Content-Disposition: inline --FsscpQKzF/jJk6ya Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Feb 10, 2021 at 03:42:51PM +0000, Dave Martin wrote: > On Wed, Feb 10, 2021 at 02:54:52PM +0000, Mark Brown wrote: > > Oh, *that's* what that's all about. I spent quite a bit of time trying > > to figure out why we were sometimes using vq_minus_1 but never managed > > to get to the bottom of it - it's an awkward name and there's nothing in > > the code that explains the logic behind when we use it so it was really > > confusing. We can do the rename but I'm not sure it's achieving the > > goal of comprehensibility. > Ah, I see. The reason for the difference is that the vector length is > encoded in ZCR_ELx.LEN as the vector length in quadwords ("vq" -- see > Documentation/arm64/sve.rst) minus one. It seemed poor practice to do > the conversion in asm where the compiler can't see or optimise it, plus > I didn't want the possibility of passing meaningless values at that > level. So the caller has to validate the vector length with > sve_vl_valid() where deemed necessary, and then convert explicitly. Yeah, it's relatively clear to get to the fact that it's due to the ZCR_ELx.LEN - what was not at all clear was what the rule for choosing between the two representations was, my instinct would've been to hide the different representation, something like a static inline wrapper for the assembly function would still let the compiler see what's going on. =20 > Either way, calling this "vl" is breaking a useful convention that's > followed throughout the rest of the kernel, so I'd prefer we call it > something else -- but within reason, I don't mind what name is used. That's the convention in the arm64 FP code or something else? --FsscpQKzF/jJk6ya Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmAkFIIACgkQJNaLcl1U h9CnAgf/ZPdFmH5g974GVleWg92jOFqQe9Rj+EUz5YlOOR5YjKLf0ohw4CEoT2UA BrpgvKrlY84zecanLvfmM2Kp+PNEJNM6Hf3aCBXEhatIoqV9vqbgBiw3P8M2l87k MqGxu3PRMujI7+lUj1GSzICyrcxUEtBrGvbF6knapX5ix8fqL/jeDjNvGxKbraTq 9jsHzm2kcaUTAEkmjUSgUwi2cwil1EhPeY/wWvhp4fMH9qiidtfBQUe8sWcyAyU/ ZMRYZgrpiZcEF/oELVDdgKboMg7x/NtLYQ5VkCdFKj6rUfDUNI8WaQywen+m5eaJ 7L0mmDTX708HTqEFsikHFYR4vuFvsg== =saDw -----END PGP SIGNATURE----- --FsscpQKzF/jJk6ya-- --===============1938726939502056056== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============1938726939502056056==--