From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v5 15/30] arm64/sve: Signal handling support Date: Tue, 12 Dec 2017 10:40:30 +0000 Message-ID: <20171212104030.GG28301@arm.com> References: <1509465082-30427-1-git-send-email-Dave.Martin@arm.com> <1509465082-30427-16-git-send-email-Dave.Martin@arm.com> <20171207104948.GE31900@arm.com> <20171211140720.GE2141@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:41940 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751507AbdLLKkX (ORCPT ); Tue, 12 Dec 2017 05:40:23 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-arch-owner@vger.kernel.org List-ID: To: Kees Cook Cc: Dave Martin , linux-arm-kernel@lists.infradead.org, linux-arch , Okamoto Takayuki , libc-alpha , Ard Biesheuvel , Szabolcs Nagy , Catalin Marinas , Alex =?iso-8859-1?Q?Benn=E9e?= , kvmarm@lists.cs.columbia.edu On Mon, Dec 11, 2017 at 11:23:09AM -0800, Kees Cook wrote: > On Mon, Dec 11, 2017 at 6:07 AM, Will Deacon wrote: > > On Thu, Dec 07, 2017 at 10:50:38AM -0800, Kees Cook wrote: > >> My question is mainly: why not just use copy_*() everywhere instead? > >> Having these things so spread out makes it fragile, and there's very > >> little performance benefit from using __copy_*() over copy_*(). > > > > I think that's more of a general question. Why not just remove the __ > > versions from the kernel entirely if they're not worth the perf? > > That has been something Linus has strongly suggested in the past, so > I've kind of been looking for easy places to drop the __copy_* > versions. :) Tell you what then: I'll Ack the arm64 patch if it's part of a series removing the thing entirely :p I guess we'd still want to the validation of the whole sigframe though, so we don't end up pushing half a signal stack before running into an access_ok failure? Will From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Tue, 12 Dec 2017 10:40:30 +0000 Subject: [PATCH v5 15/30] arm64/sve: Signal handling support In-Reply-To: References: <1509465082-30427-1-git-send-email-Dave.Martin@arm.com> <1509465082-30427-16-git-send-email-Dave.Martin@arm.com> <20171207104948.GE31900@arm.com> <20171211140720.GE2141@arm.com> Message-ID: <20171212104030.GG28301@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Dec 11, 2017 at 11:23:09AM -0800, Kees Cook wrote: > On Mon, Dec 11, 2017 at 6:07 AM, Will Deacon wrote: > > On Thu, Dec 07, 2017 at 10:50:38AM -0800, Kees Cook wrote: > >> My question is mainly: why not just use copy_*() everywhere instead? > >> Having these things so spread out makes it fragile, and there's very > >> little performance benefit from using __copy_*() over copy_*(). > > > > I think that's more of a general question. Why not just remove the __ > > versions from the kernel entirely if they're not worth the perf? > > That has been something Linus has strongly suggested in the past, so > I've kind of been looking for easy places to drop the __copy_* > versions. :) Tell you what then: I'll Ack the arm64 patch if it's part of a series removing the thing entirely :p I guess we'd still want to the validation of the whole sigframe though, so we don't end up pushing half a signal stack before running into an access_ok failure? Will