From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=dZYZ=32=lists.ozlabs.org=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@kernel.org>
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=-9.8 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_GIT 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 4F1BCC35247
	for <linuxppc-dev@archiver.kernel.org>; Thu,  6 Feb 2020 03:05:42 +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 09F5E214AF
	for <linuxppc-dev@archiver.kernel.org>; Thu,  6 Feb 2020 03:05:41 +0000 (UTC)
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 09F5E214AF
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com
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 48Cjwz6mPDzDqBs
	for <linuxppc-dev@archiver.kernel.org>; Thu,  6 Feb 2020 14:05:39 +1100 (AEDT)
Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized)
 smtp.mailfrom=huawei.com (client-ip=45.249.212.35; helo=huawei.com;
 envelope-from=yanaijie@huawei.com; receiver=<UNKNOWN>)
Authentication-Results: lists.ozlabs.org;
 dmarc=none (p=none dis=none) header.from=huawei.com
Received: from huawei.com (szxga07-in.huawei.com [45.249.212.35])
 (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 48Cjp85hrbzDqTQ
 for <linuxppc-dev@lists.ozlabs.org>; Thu,  6 Feb 2020 13:59:42 +1100 (AEDT)
Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.58])
 by Forcepoint Email with ESMTP id 2004A7B2BCFD0EE927FF;
 Thu,  6 Feb 2020 10:59:35 +0800 (CST)
Received: from huawei.com (10.175.124.28) by DGGEMS401-HUB.china.huawei.com
 (10.3.19.201) with Microsoft SMTP Server id 14.3.439.0; Thu, 6 Feb 2020
 10:59:28 +0800
From: Jason Yan <yanaijie@huawei.com>
To: <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>,
 <oss@buserror.net>
Subject: [PATCH v3 4/6] powerpc/fsl_booke/64: do not clear the BSS for the
 second pass
Date: Thu, 6 Feb 2020 10:58:23 +0800
Message-ID: <20200206025825.22934-5-yanaijie@huawei.com>
X-Mailer: git-send-email 2.17.2
In-Reply-To: <20200206025825.22934-1-yanaijie@huawei.com>
References: <20200206025825.22934-1-yanaijie@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
X-Originating-IP: [10.175.124.28]
X-CFilter-Loop: Reflected
X-BeenThere: linuxppc-dev@lists.ozlabs.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Linux on PowerPC Developers Mail List <linuxppc-dev.lists.ozlabs.org>
List-Unsubscribe: <https://lists.ozlabs.org/options/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>
List-Archive: <http://lists.ozlabs.org/pipermail/linuxppc-dev/>
List-Post: <mailto:linuxppc-dev@lists.ozlabs.org>
List-Help: <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=help>
List-Subscribe: <https://lists.ozlabs.org/listinfo/linuxppc-dev>,
 <mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>
Cc: Jason Yan <yanaijie@huawei.com>, linux-kernel@vger.kernel.org,
 zhaohongjiang@huawei.com
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

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 <yanaijie@huawei.com>
Cc: Scott Wood <oss@buserror.net>
Cc: Diana Craciun <diana.craciun@nxp.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
---
 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
+
 	/* Clear out the BSS. It may have been done in prom_init,
 	 * already but that's irrelevant since prom_init will soon
 	 * be detached from the kernel completely. Besides, we need
-- 
2.17.2