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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 361CBC04AAF for ; Thu, 16 May 2019 11:07:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02C5020848 for ; Thu, 16 May 2019 11:07:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726906AbfEPLHb (ORCPT ); Thu, 16 May 2019 07:07:31 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:56858 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726363AbfEPLHa (ORCPT ); Thu, 16 May 2019 07:07:30 -0400 Received: from pps.filterd (m0098413.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x4GAvt2Q133883 for ; Thu, 16 May 2019 07:07:29 -0400 Received: from e06smtp07.uk.ibm.com (e06smtp07.uk.ibm.com [195.75.94.103]) by mx0b-001b2d01.pphosted.com with ESMTP id 2sh6cas43k-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Thu, 16 May 2019 07:07:28 -0400 Received: from localhost by e06smtp07.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Thu, 16 May 2019 12:07:20 +0100 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x4GB7Jc336438152 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 16 May 2019 11:07:19 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 31EFC4C04A; Thu, 16 May 2019 11:07:19 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D1A4E4C044; Thu, 16 May 2019 11:07:17 +0000 (GMT) Received: from rapoport-lnx (unknown [9.148.8.112]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Thu, 16 May 2019 11:07:17 +0000 (GMT) Date: Thu, 16 May 2019 14:07:16 +0300 From: Mike Rapoport To: Ard Biesheuvel Cc: Hsin-Yi Wang , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" , Rob Herring , Mark Rutland , Frank Rowand , Devicetree List , Linux Kernel Mailing List , Stephen Boyd , Kees Cook , Rasmus Villemoes , Architecture Mailman List , Catalin Marinas , Will Deacon , Andrew Morton , Michal Hocko , Miles Chen , James Morse , Andrew Murray Subject: Re: [PATCH v2 2/2] amr64: map FDT as RW for early_init_dt_scan() References: <20190513003819.356-1-hsinyi@chromium.org> <20190513003819.356-2-hsinyi@chromium.org> <20190513085853.GB9271@rapoport-lnx> <20190514154223.GA11115@rapoport-lnx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-TM-AS-GCONF: 00 x-cbid: 19051611-0028-0000-0000-0000036E4F1D X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19051611-0029-0000-0000-0000242DE950 Message-Id: <20190516110715.GA19122@rapoport-lnx> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-05-16_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1905160074 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 15, 2019 at 10:11:53PM +0200, Ard Biesheuvel wrote: > On Wed, 15 May 2019 at 12:24, Hsin-Yi Wang wrote: > > > > On Tue, May 14, 2019 at 11:42 PM Mike Rapoport wrote: > > > > > I'm not sure if early console is available at the time kaslr_early_init() > > > is called, but if yes, running with memblock=debug may shed some light. > > > > > > > I didn't trace the real reason causing this. But in this case, maybe > > > > don't call memblock_reserve() in kaslr? > > > > > > My concern that this uncovered a real bug which might hit us later. > > > > > Hi Mike, > > Thanks for the hint. I tried on my device but seems that earlycon > > happens after the warning call trace, so can't more information. > > > > Since on my device kaslr will be runned, I tried call > > memblock_reserve() in kaslr and not in > > setup_machine_fdt()#fixmap_remap_fdt, but got following warning > > > > I realize this is not documented sufficiently in the commit log, but > the reason I introduced the separate __fixmap_remap_fdt() [which does > not call memblock_reserve()] was that the KASLR init code should set > as little global state as possible, given that it is called with the > kernel mapped at the wrong virtual address. > > The KASLR boot sequence is something like > - map kernel at default [unrandomized] address > - apply relocations and clear BSS > - run KASLR init to map and parse the FDT [*] > - if KASLR is enabled, unmap the kernel and remap it at the randomized address > - apply relocations and clear BSS > - proceed with start_kernel() > > The issue you are seeing is caused by the fact that the memblock > bookkeeping gets into an inconsistent state due to the 2nd clearing of > BSS. Ah, now the warning makes perfect sense :) Thanks! > [*] The reason we need to map the FDT this early is to obtain the > random seed, and to check whether 'nokaslr' was passed on the kernel > command line. The reason arm64 deviates from other architectures in > this regard is that we don't have a decompressor, and so there is no > other execution context available where we can run C code to parse the > FDT etc before we enter the kernel proper. > > > > > > [ 0.000000] memblock_remove: > > [0x0001000000000000-0x0000fffffffffffe] arm64_memblock_init+0x28/0x224 > > [ 0.000000] memblock_remove: > > [0x0000004040000000-0x000000403ffffffe] arm64_memblock_init+0x64/0x224 > > [ 0.000000] memblock_reserve: > > [0x0000000040080000-0x00000000413c3fff] > > arm64_memblock_init+0x188/0x224 > > [ 0.000000] WARNING: CPU: 0 PID: 0 at > > /mnt/host/source/src/third_party/kernel/v4.19/mm/memblock.c:583 > > memblock_add_range+0x1bc/0x1c8 > > [ 0.000000] Modules linked in: > > [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.19.38 #222 > > [ 0.000000] Hardware name: MediaTek kukui rev2 board (DT) > > [ 0.000000] pstate: 60000085 (nZCv daIf -PAN -UAO) > > [ 0.000000] pc : memblock_add_range+0x1bc/0x1c8 > > [ 0.000000] lr : memblock_add_range+0x30/0x1c8 > > [ 0.000000] sp : ffffffab68603ea0 > > [ 0.000000] x29: ffffffab68603ef0 x28: 0000000040954324 > > [ 0.000000] x27: 0000000040080000 x26: 0000000000080000 > > [ 0.000000] x25: 0000000080127e4b x24: ffffffab68716000 > > [ 0.000000] x23: ffffffab680b5000 x22: 0000000001344000 > > [ 0.000000] x21: 0000000040080000 x20: 0000000000000000 > > [ 0.000000] x19: ffffffab6864bf00 x18: 00000000fffffc94 > > [ 0.000000] x17: 000000000000003c x16: ffffffab67d49064 > > [ 0.000000] x15: 0000000000000006 x14: 626d656d5f34366d > > [ 0.000000] x13: 7261205d66666633 x12: 0000000000000000 > > [ 0.000000] x11: 0000000000000000 x10: ffffffffffffffff > > [ 0.000000] x9 : 0000000000011547 x8 : ffffffab68765690 > > [ 0.000000] x7 : 696e695f6b636f6c x6 : ffffffab6875dd41 > > [ 0.000000] x5 : 0000000000000000 x4 : 0000000000000000 > > [ 0.000000] x3 : ffffffab678a24a0 x2 : 0000000001344000 > > [ 0.000000] x1 : 0000000040080000 x0 : ffffffab6864bf00 > > [ 0.000000] Call trace: > > [ 0.000000] memblock_add_range+0x1bc/0x1c8 > > [ 0.000000] memblock_reserve+0x60/0xac > > [ 0.000000] arm64_memblock_init+0x188/0x224 > > [ 0.000000] setup_arch+0x138/0x19c > > [ 0.000000] start_kernel+0x68/0x380 > > [ 0.000000] random: get_random_bytes called from > > print_oops_end_marker+0x3c/0x58 with crng_init=0 > > [ 0.000000] ---[ end trace ea99802b425f7adf ]--- > > [ 0.000000] memblock_reserve: > > [0x000000005f800000-0x000000005f811536] > > early_init_dt_reserve_memory_arch+0x38/0x48 > > [ 0.000000] memblock_reserve: > > [0x00000000ffe00000-0x00000000ffffffff] > > early_init_dt_reserve_memory_arch+0x38/0x48 > > > > So I guess we just can't call memblock_reserve() in kaslr? > -- Sincerely yours, Mike.