From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Thu, 31 May 2018 23:30:15 +0200 (CEST) Received: from mail.kernel.org ([198.145.29.99]:60474 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S23994688AbeEaVaIbIqDJ (ORCPT ); Thu, 31 May 2018 23:30:08 +0200 Received: from jamesdev (jahogan.plus.com [212.159.75.221]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A80B220890; Thu, 31 May 2018 21:30:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1527802201; bh=Vy2nIzyMSNLPsCeLMsX7X225soO5TlUCIhqk16jg6yc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gcHBk3OvfuDbrB581sY2LS7gtyDb8fxa6F469Q41tqZxRVtP1v3diIuwZmxiexJwE kd3uBFvWd/+1qeCAp5dvSPtSO+aifNpHc2URE+ZX1FmPRj72eqisPrp0LKte/r5UIS Qfv3gFLVdjZtd1KAVrwHKbRf+rsBG5xQxIIYa6dU= Date: Thu, 31 May 2018 22:29:57 +0100 From: James Hogan To: "Maciej W. Rozycki" Cc: Ralf Baechle , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] MIPS: prctl: Disallow FRE without FR with PR_SET_FP_MODE requests Message-ID: <20180531212956.GA30406@jamesdev> References: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="u3/rZRmxL6MmkK24" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 64137 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: jhogan@kernel.org Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips --u3/rZRmxL6MmkK24 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, May 15, 2018 at 11:04:44PM +0100, Maciej W. Rozycki wrote: > Having PR_FP_MODE_FRE (i.e. Config5.FRE) set without PR_FP_MODE_FR (i.e.= =20 > Status.FR) is not supported as the lone purpose of Config5.FRE is to=20 > emulate Status.FR=3D0 handling on FPU hardware that has Status.FR=3D1=20 > hardwired[1][2]. Also we do not handle this case elsewhere, and assume= =20 > throughout our code that TIF_HYBRID_FPREGS and TIF_32BIT_FPREGS cannot=20 > be set both at once for a task, leading to inconsistent behaviour if=20 > this does happen. >=20 > Return unsuccessfully then from prctl(2) PR_SET_FP_MODE calls requesting= =20 > PR_FP_MODE_FRE to be set with PR_FP_MODE_FR clear. This corresponds to= =20 > modes allowed by `mips_set_personality_fp'. >=20 > References: >=20 > [1] "MIPS Architecture For Programmers, Vol. III: MIPS32 / microMIPS32 > Privileged Resource Architecture", Imagination Technologies, > Document Number: MD00090, Revision 6.02, July 10, 2015, Table 9.69=20 > "Config5 Register Field Descriptions", p. 262 >=20 > [2] "MIPS Architecture For Programmers, Volume III: MIPS64 / microMIPS64= =20 > Privileged Resource Architecture", Imagination Technologies,=20 > Document Number: MD00091, Revision 6.03, December 22, 2015, Table=20 > 9.72 "Config5 Register Field Descriptions", p. 288 >=20 > Cc: stable@vger.kernel.org # 4.0+ > Fixes: 9791554b45a2 ("MIPS,prctl: add PR_[GS]ET_FP_MODE prctl options for= MIPS") > Signed-off-by: Maciej W. Rozycki Thanks, applied to mips-fixes, hopefully for 4.17 (but if it misses tomorrows linux-next it may have to wait 'til 4.18). Cheers James --u3/rZRmxL6MmkK24 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iHUEARYIAB0WIQS7lRNBWUYtqfDOVL41zuSGKxAj8gUCWxBpUwAKCRA1zuSGKxAj 8nD+AQDlX/YPX/WyufbGvOmzQO3ows5pmEBYDLTntCMjLwfQLAEA9ODc1Qt8srfM nrZ+PcIffTYPGEghVp1HHUcl1GHBqwU= =UY2D -----END PGP SIGNATURE----- --u3/rZRmxL6MmkK24--