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 X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F1224C3F2CE for ; Thu, 5 Mar 2020 03:15:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D20B1214D8 for ; Thu, 5 Mar 2020 03:15:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725938AbgCEDPO (ORCPT ); Wed, 4 Mar 2020 22:15:14 -0500 Received: from szxga07-in.huawei.com ([45.249.212.35]:42170 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725844AbgCEDPO (ORCPT ); Wed, 4 Mar 2020 22:15:14 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id B11B318CE46A3B88F89C; Thu, 5 Mar 2020 11:15:07 +0800 (CST) Received: from [127.0.0.1] (10.173.221.195) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.439.0; Thu, 5 Mar 2020 11:14:59 +0800 Subject: Re: [PATCH v3 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass To: Scott Wood , , , , , , , , , CC: , References: <20200206025825.22934-1-yanaijie@huawei.com> <20200206025825.22934-5-yanaijie@huawei.com> From: Jason Yan Message-ID: Date: Thu, 5 Mar 2020 11:14:59 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.173.221.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2020/3/5 5:49, Scott Wood 写道: > On Thu, 2020-02-06 at 10:58 +0800, Jason Yan wrote: >> The BSS section has already cleared out in the first pass. No need to >> clear it again. This can save some time when booting with KASLR >> enabled. >> >> Signed-off-by: Jason Yan >> Cc: Scott Wood >> Cc: Diana Craciun >> Cc: Michael Ellerman >> Cc: Christophe Leroy >> Cc: Benjamin Herrenschmidt >> Cc: Paul Mackerras >> Cc: Nicholas Piggin >> Cc: Kees Cook >> --- >> arch/powerpc/kernel/head_64.S | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S >> index 744624140fb8..8c644e7c3eaf 100644 >> --- a/arch/powerpc/kernel/head_64.S >> +++ b/arch/powerpc/kernel/head_64.S >> @@ -914,6 +914,13 @@ start_here_multiplatform: >> bl relative_toc >> tovirt(r2,r2) >> >> + /* Do not clear the BSS for the second pass if randomized */ >> + LOAD_REG_ADDR(r3, kernstart_virt_addr) >> + lwz r3,0(r3) >> + LOAD_REG_IMMEDIATE(r4, KERNELBASE) >> + cmpw r3,r4 >> + bne 4f > > These are 64-bit values. > Oh yes, will fix. Thanks. > -Scott > > > > . >