Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752718AbeAQKHM (ORCPT + 1 other); Wed, 17 Jan 2018 05:07:12 -0500 Received: from foss.arm.com ([217.140.101.70]:37764 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752424AbeAQKHK (ORCPT ); Wed, 17 Jan 2018 05:07:10 -0500 Date: Wed, 17 Jan 2018 10:07:15 +0000 From: Will Deacon To: Yisheng Xie Cc: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, ard.biesheuvel@linaro.org, marc.zyngier@arm.com, lorenzo.pieralisi@arm.com, christoffer.dall@linaro.org, linux-kernel@vger.kernel.org, labbott@redhat.com Subject: Re: [PATCH v2 07/11] arm64: Add skeleton to harden the branch predictor against aliasing attacks Message-ID: <20180117100715.GA27892@arm.com> References: <1515157961-20963-1-git-send-email-will.deacon@arm.com> <1515157961-20963-8-git-send-email-will.deacon@arm.com> <01c224eb-9bec-6b16-7ecf-14837cc107b6@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <01c224eb-9bec-6b16-7ecf-14837cc107b6@huawei.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Wed, Jan 17, 2018 at 12:10:33PM +0800, Yisheng Xie wrote: > Hi Will, > > On 2018/1/5 21:12, Will Deacon wrote: > > diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c > > index 5f7097d0cd12..d99b36555a16 100644 > > --- a/arch/arm64/mm/context.c > > +++ b/arch/arm64/mm/context.c > > @@ -246,6 +246,8 @@ asmlinkage void post_ttbr_update_workaround(void) > > "ic iallu; dsb nsh; isb", > > ARM64_WORKAROUND_CAVIUM_27456, > > CONFIG_CAVIUM_ERRATUM_27456)); > > + > > + arm64_apply_bp_hardening(); > > } > > post_ttbr_update_workaround was used for fix Cavium erratum 2745? so does that > means, if we do not have this erratum, we do not need arm64_apply_bp_hardening()? > when mm_swtich and kernel_exit? > > From the code logical, it seems not only related to erratum 2745 anymore? > should it be renamed? post_ttbr_update_workaround just runs code after a TTBR update, which includes mitigations against variant 2 of "spectre" and also a workaround for a Cavium erratum. These are separate issues. Will