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 5A6ABC7618B for ; Mon, 29 Jul 2019 14:04:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 37D1B216C8 for ; Mon, 29 Jul 2019 14:04:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728386AbfG2OEq (ORCPT ); Mon, 29 Jul 2019 10:04:46 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:3234 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727461AbfG2OEp (ORCPT ); Mon, 29 Jul 2019 10:04:45 -0400 Received: from DGGEMS401-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id CCB4D861A3D54308FD35; Mon, 29 Jul 2019 22:04:41 +0800 (CST) Received: from [127.0.0.1] (10.177.96.203) by DGGEMS401-HUB.china.huawei.com (10.3.19.201) with Microsoft SMTP Server id 14.3.439.0; Mon, 29 Jul 2019 22:04:32 +0800 Subject: Re: [RFC PATCH 09/10] powerpc/fsl_booke/kaslr: support nokaslr cmdline parameter To: Christophe Leroy , , , , , , , , CC: , , , , , References: <20190717080621.40424-1-yanaijie@huawei.com> <20190717080621.40424-10-yanaijie@huawei.com> From: Jason Yan Message-ID: <846fa5fc-5d21-d974-e021-c314b554fa51@huawei.com> Date: Mon, 29 Jul 2019 22:04:31 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.177.96.203] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/7/29 19:38, Christophe Leroy wrote: > > > Le 17/07/2019 à 10:06, Jason Yan a écrit : >> One may want to disable kaslr when boot, so provide a cmdline parameter >> 'nokaslr' to support this. >> >> Signed-off-by: Jason Yan >> Cc: Diana Craciun >> Cc: Michael Ellerman >> Cc: Christophe Leroy >> Cc: Benjamin Herrenschmidt >> Cc: Paul Mackerras >> Cc: Nicholas Piggin >> Cc: Kees Cook >> --- >>   arch/powerpc/kernel/kaslr_booke.c | 14 ++++++++++++++ >>   1 file changed, 14 insertions(+) >> >> diff --git a/arch/powerpc/kernel/kaslr_booke.c >> b/arch/powerpc/kernel/kaslr_booke.c >> index 00339c05879f..e65a5d9d2ff1 100644 >> --- a/arch/powerpc/kernel/kaslr_booke.c >> +++ b/arch/powerpc/kernel/kaslr_booke.c >> @@ -373,6 +373,18 @@ static unsigned long __init >> kaslr_choose_location(void *dt_ptr, phys_addr_t size >>       return kaslr_offset; >>   } >> +static inline __init bool kaslr_disabled(void) >> +{ >> +    char *str; >> + >> +    str = strstr(early_command_line, "nokaslr"); > > Why using early_command_line instead of boot_command_line ? > Will switch to boot_command_line. > >> +    if ((str == early_command_line) || >> +        (str > early_command_line && *(str - 1) == ' ')) > > Is that stuff really needed ? > > Why not just: > > return strstr(early_command_line, "nokaslr") != NULL; > This code is derived from other arch such as arm64/mips. It's trying to make sure that 'nokaslr' is a separate word but not part of other words such as 'abcnokaslr'. >> +        return true; >> + >> +    return false; >> +} > > >> + >>   /* >>    * To see if we need to relocate the kernel to a random offset >>    * void *dt_ptr - address of the device tree >> @@ -388,6 +400,8 @@ notrace void __init kaslr_early_init(void *dt_ptr, >> phys_addr_t size) >>       kernel_sz = (unsigned long)_end - KERNELBASE; >>       kaslr_get_cmdline(dt_ptr); >> +    if (kaslr_disabled()) >> +        return; >>       offset = kaslr_choose_location(dt_ptr, size, kernel_sz); >> > > Christophe > > . >