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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1B671C433FE for ; Mon, 11 Oct 2021 11:48:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 009F26109E for ; Mon, 11 Oct 2021 11:48:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231659AbhJKLum (ORCPT ); Mon, 11 Oct 2021 07:50:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:37274 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236114AbhJKLum (ORCPT ); Mon, 11 Oct 2021 07:50:42 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EF39060E0C; Mon, 11 Oct 2021 11:48:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633952922; bh=Z1/JhxxEatT+l2NqNuffCCtFx2fY6SMTSZ9VwNJdlFY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oSEL6Y5FvTC7jFnEaXT5jMyBdAGK7dV3+aeP6Jg5KmH3Oh9SlxaqQMxXLsrvsjXXf 55pxBu4ja90fq+ruvavx7yZlYoQs7OuxnCKkRJ5V6f/b/SX805suGscqUplucklBqx 7GqjrZi4NnLG27CKab16cUQRmjjUZL58xETuUwIJui+dwxNp5dHhBGW9P9Ev3p1j6P cstCT/4/rdQHRkzFU3XbWyFnZStXxiwhZ30wrpReJ3kLIZL85eAUADSc05IU+8fNUw Y3u4axrlhJ2xSgQFxv6A0MII1F/Krq9e0hdBp2icVI21iviJkSYtdpyN9I+cGERBPo qq3oXJHgC9yyw== Date: Mon, 11 Oct 2021 12:48:40 +0100 From: Mark Brown To: Alan Hayward Cc: Catalin Marinas , Will Deacon , Shuah Khan , Shuah Khan , Luis Machado , Salil Akerkar , Basant KumarDwivedi , Szabolcs Nagy , "linux-arm-kernel@lists.infradead.org" , "linux-kselftest@vger.kernel.org" , nd Subject: Re: [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME Message-ID: References: <20210930181144.10029-1-broonie@kernel.org> <20210930181144.10029-13-broonie@kernel.org> <59675B79-E426-4177-8A4E-43026E42B9E3@arm.com> <0749CCC0-CCEF-4869-9F55-FD9AC97CBA67@arm.com> <78C51A1B-DF42-463B-9B1D-AE96756C5854@arm.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="YByx5LhWlp99fXXV" Content-Disposition: inline In-Reply-To: <78C51A1B-DF42-463B-9B1D-AE96756C5854@arm.com> X-Cookie: Your ignorance cramps my conversation. Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org --YByx5LhWlp99fXXV Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 11, 2021 at 11:15:09AM +0000, Alan Hayward wrote: > > On 8 Oct 2021, at 18:04, Mark Brown wrote: > > I will if/when it gets fixed that way. Actually, while looking > > at that code I was tempted to remove the support for returning > > FPSIMD only registers via NT_ARM_SVE entirely and just always > > convert to SVE format - I'm not sure what the use case was there? > > It's not a pressing thing but it seemed like it was a bit of an > > implementation detail that we were revealing. > What about in the write registers case? Both register sets accept FPSIMD registers for writes - we can't remove that for the SVE register set given that it's ABI. > With the existing code: > Read SVE registers with ptrace. Get FPSIMD. Update FPSIMD with new values= =2E Write back to ptrace. > In that scenario, the internal SVE states stays =E2=80=9Cinactive=E2=80= =9D in the kernel. Right. > If ptrace always returned an SVE structure, then writing back with the sa= me structure would cause the > SVE state to become active. It=E2=80=99s a small difference, but we reall= y don=E2=80=99t want the debugger to effect things. With the existing code - with the wider availability of SVE hardware we'll see soon we might be looking at changing how the kernel handles enabling and disabling SVE which might mean we want to change how that looks internally anyway. Part of what has me thinking about this is that what we've got at the minute is quite tied to the implementation and we might want to change that. --YByx5LhWlp99fXXV Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmFkJJcACgkQJNaLcl1U h9BHqgf/bX8EzVZFKTIoBVOMUJIlFJ9rtZwWjw6JQkjf525ToIDJQORSPghVbO23 RMPHuwLkkyJ6kmIOo35wDG6A4u+mDloEGokvmtfuAHdAIdFQbNDvnMUCfZWRpRz4 LMFoxwqu/iyFsuHB0e+/H/BN1Ac4HBWSGKFG2JSiivzqJQOpS3CMFUscI+T16bRI dwnXmEz0/CRoiqtQmLje7M/nvSoy4AKk4sY+TFREi+jvD6To+ynrWx/5eVvk/i8d lwPNreWw1oMCNjW/8ZLH2FkhzXdj8usuw+pYnm7TYJlyfvBySLYlTEJL2bUN13/n sAz+pXFplABmLPYbNUIStBDTc5gM5w== =Uo00 -----END PGP SIGNATURE----- --YByx5LhWlp99fXXV-- 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8160C433EF for ; Mon, 11 Oct 2021 11:51:46 +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 9A7E060F21 for ; Mon, 11 Oct 2021 11:51:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9A7E060F21 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: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-Transfer-Encoding:Content-ID:Content-Description:Resent-Date :Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=SCQlUFxnmiRw8fcJJ6qkJk45aTMrpj/vbVII8DAo/m0=; b=WEsimgk/MNW+GdIsFEpZ+si6tt jer2POFs/kJlNEc+s9g3OCRE8YwQdkJNDN3UwSi5sKtndr0xN3sijNf+8NPAoavLKxZVgJZyMTc2H chQw1d2ES8PpUH78Su8+XOPUdZpRWF0jnZhQsuu9tQFFQ8OEGuWhYU0AhfrgVDf5CrGpcNSuK+vNy 6HEH94BvJdnmz78vYco0Db2Z8oYXluqUCIvJn7GE38LN5SM2wKTGFiUh8UHApREGxNNix/MILuZQ4 lYn6XHZ2HBpVcdk4NE37PVyeKTVLKhJ7rUV8Y45w5O0sA5LCdYUpQkgUkwWUhON95k5gBTsvUGLUH qWGSQuQQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mZtnc-009CHp-RY; Mon, 11 Oct 2021 11:48:57 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mZtnP-009CFU-2y for linux-arm-kernel@lists.infradead.org; Mon, 11 Oct 2021 11:48:44 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id EF39060E0C; Mon, 11 Oct 2021 11:48:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1633952922; bh=Z1/JhxxEatT+l2NqNuffCCtFx2fY6SMTSZ9VwNJdlFY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=oSEL6Y5FvTC7jFnEaXT5jMyBdAGK7dV3+aeP6Jg5KmH3Oh9SlxaqQMxXLsrvsjXXf 55pxBu4ja90fq+ruvavx7yZlYoQs7OuxnCKkRJ5V6f/b/SX805suGscqUplucklBqx 7GqjrZi4NnLG27CKab16cUQRmjjUZL58xETuUwIJui+dwxNp5dHhBGW9P9Ev3p1j6P cstCT/4/rdQHRkzFU3XbWyFnZStXxiwhZ30wrpReJ3kLIZL85eAUADSc05IU+8fNUw Y3u4axrlhJ2xSgQFxv6A0MII1F/Krq9e0hdBp2icVI21iviJkSYtdpyN9I+cGERBPo qq3oXJHgC9yyw== Date: Mon, 11 Oct 2021 12:48:40 +0100 From: Mark Brown To: Alan Hayward Cc: Catalin Marinas , Will Deacon , Shuah Khan , Shuah Khan , Luis Machado , Salil Akerkar , Basant KumarDwivedi , Szabolcs Nagy , "linux-arm-kernel@lists.infradead.org" , "linux-kselftest@vger.kernel.org" , nd Subject: Re: [PATCH v1 12/38] arm64/sme: Provide ABI documentation for SME Message-ID: References: <20210930181144.10029-1-broonie@kernel.org> <20210930181144.10029-13-broonie@kernel.org> <59675B79-E426-4177-8A4E-43026E42B9E3@arm.com> <0749CCC0-CCEF-4869-9F55-FD9AC97CBA67@arm.com> <78C51A1B-DF42-463B-9B1D-AE96756C5854@arm.com> MIME-Version: 1.0 In-Reply-To: <78C51A1B-DF42-463B-9B1D-AE96756C5854@arm.com> X-Cookie: Your ignorance cramps my conversation. X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211011_044843_217245_2FAB63CC X-CRM114-Status: GOOD ( 21.67 ) 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: multipart/mixed; boundary="===============8124717033182922283==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============8124717033182922283== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="YByx5LhWlp99fXXV" Content-Disposition: inline --YByx5LhWlp99fXXV Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 11, 2021 at 11:15:09AM +0000, Alan Hayward wrote: > > On 8 Oct 2021, at 18:04, Mark Brown wrote: > > I will if/when it gets fixed that way. Actually, while looking > > at that code I was tempted to remove the support for returning > > FPSIMD only registers via NT_ARM_SVE entirely and just always > > convert to SVE format - I'm not sure what the use case was there? > > It's not a pressing thing but it seemed like it was a bit of an > > implementation detail that we were revealing. > What about in the write registers case? Both register sets accept FPSIMD registers for writes - we can't remove that for the SVE register set given that it's ABI. > With the existing code: > Read SVE registers with ptrace. Get FPSIMD. Update FPSIMD with new values= =2E Write back to ptrace. > In that scenario, the internal SVE states stays =E2=80=9Cinactive=E2=80= =9D in the kernel. Right. > If ptrace always returned an SVE structure, then writing back with the sa= me structure would cause the > SVE state to become active. It=E2=80=99s a small difference, but we reall= y don=E2=80=99t want the debugger to effect things. With the existing code - with the wider availability of SVE hardware we'll see soon we might be looking at changing how the kernel handles enabling and disabling SVE which might mean we want to change how that looks internally anyway. Part of what has me thinking about this is that what we've got at the minute is quite tied to the implementation and we might want to change that. --YByx5LhWlp99fXXV Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAABCgAdFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAmFkJJcACgkQJNaLcl1U h9BHqgf/bX8EzVZFKTIoBVOMUJIlFJ9rtZwWjw6JQkjf525ToIDJQORSPghVbO23 RMPHuwLkkyJ6kmIOo35wDG6A4u+mDloEGokvmtfuAHdAIdFQbNDvnMUCfZWRpRz4 LMFoxwqu/iyFsuHB0e+/H/BN1Ac4HBWSGKFG2JSiivzqJQOpS3CMFUscI+T16bRI dwnXmEz0/CRoiqtQmLje7M/nvSoy4AKk4sY+TFREi+jvD6To+ynrWx/5eVvk/i8d lwPNreWw1oMCNjW/8ZLH2FkhzXdj8usuw+pYnm7TYJlyfvBySLYlTEJL2bUN13/n sAz+pXFplABmLPYbNUIStBDTc5gM5w== =Uo00 -----END PGP SIGNATURE----- --YByx5LhWlp99fXXV-- --===============8124717033182922283== 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 --===============8124717033182922283==--