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_2 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 1F72EC3F2CE for ; Wed, 4 Mar 2020 21:49:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F1B012084E for ; Wed, 4 Mar 2020 21:49:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388463AbgCDVtt (ORCPT ); Wed, 4 Mar 2020 16:49:49 -0500 Received: from baldur.buserror.net ([165.227.176.147]:34440 "EHLO baldur.buserror.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388312AbgCDVts (ORCPT ); Wed, 4 Mar 2020 16:49:48 -0500 Received: from [2601:449:8480:af0:12bf:48ff:fe84:c9a0] by baldur.buserror.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1j9btL-0000ZP-0c; Wed, 04 Mar 2020 15:49:24 -0600 Message-ID: From: Scott Wood To: Jason Yan , mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com Cc: linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com Date: Wed, 04 Mar 2020 15:49:21 -0600 In-Reply-To: <20200206025825.22934-5-yanaijie@huawei.com> References: <20200206025825.22934-1-yanaijie@huawei.com> <20200206025825.22934-5-yanaijie@huawei.com> Organization: Red Hat Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2601:449:8480:af0:12bf:48ff:fe84:c9a0 X-SA-Exim-Rcpt-To: yanaijie@huawei.com, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com X-SA-Exim-Mail-From: oss@buserror.net Subject: Re: [PATCH v3 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on baldur.buserror.net) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. -Scott 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_2 autolearn=unavailable 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 1A9E7C3F2CE for ; Wed, 4 Mar 2020 21:51:56 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C793120732 for ; Wed, 4 Mar 2020 21:51:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C793120732 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=buserror.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48Xnf10L88zDqQb for ; Thu, 5 Mar 2020 08:51:53 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=buserror.net (client-ip=165.227.176.147; helo=baldur.buserror.net; envelope-from=oss@buserror.net; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=buserror.net Received: from baldur.buserror.net (baldur.buserror.net [165.227.176.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 48XnbC3xYqzDq9G for ; Thu, 5 Mar 2020 08:49:27 +1100 (AEDT) Received: from [2601:449:8480:af0:12bf:48ff:fe84:c9a0] by baldur.buserror.net with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1j9btL-0000ZP-0c; Wed, 04 Mar 2020 15:49:24 -0600 Message-ID: From: Scott Wood To: Jason Yan , mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com Date: Wed, 04 Mar 2020 15:49:21 -0600 In-Reply-To: <20200206025825.22934-5-yanaijie@huawei.com> References: <20200206025825.22934-1-yanaijie@huawei.com> <20200206025825.22934-5-yanaijie@huawei.com> Organization: Red Hat Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 2601:449:8480:af0:12bf:48ff:fe84:c9a0 X-SA-Exim-Rcpt-To: yanaijie@huawei.com, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, diana.craciun@nxp.com, christophe.leroy@c-s.fr, benh@kernel.crashing.org, paulus@samba.org, npiggin@gmail.com, keescook@chromium.org, kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com X-SA-Exim-Mail-From: oss@buserror.net Subject: Re: [PATCH v3 4/6] powerpc/fsl_booke/64: do not clear the BSS for the second pass X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on baldur.buserror.net) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-kernel@vger.kernel.org, zhaohongjiang@huawei.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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. -Scott