From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754919AbeARIhj (ORCPT ); Thu, 18 Jan 2018 03:37:39 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:51262 "EHLO huawei.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754900AbeARIhi (ORCPT ); Thu, 18 Jan 2018 03:37:38 -0500 Subject: Re: [PATCH v2 07/11] arm64: Add skeleton to harden the branch predictor against aliasing attacks To: Will Deacon 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> <20180117100715.GA27892@arm.com> CC: , , , , , , , From: Yisheng Xie Message-ID: Date: Thu, 18 Jan 2018 16:37:17 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <20180117100715.GA27892@arm.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.177.29.40] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will, On 2018/1/17 18:07, Will Deacon wrote: > 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. Get it, Thanks for your kind explain. Thanks Yisheng > > Will > > . >