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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 C8F88C433E0 for ; Mon, 22 Mar 2021 07:59:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8250861982 for ; Mon, 22 Mar 2021 07:59:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229992AbhCVH7B (ORCPT ); Mon, 22 Mar 2021 03:59:01 -0400 Received: from gecko.sbs.de ([194.138.37.40]:60831 "EHLO gecko.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229870AbhCVH6q (ORCPT ); Mon, 22 Mar 2021 03:58:46 -0400 Received: from mail2.sbs.de (mail2.sbs.de [192.129.41.66]) by gecko.sbs.de (8.15.2/8.15.2) with ESMTPS id 12M7wYCD021043 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 22 Mar 2021 08:58:35 +0100 Received: from [167.87.37.70] ([167.87.37.70]) by mail2.sbs.de (8.15.2/8.15.2) with ESMTP id 12M7wY2u002040; Mon, 22 Mar 2021 08:58:34 +0100 Subject: Re: [PATCH] of/fdt: Make sure no-map does not remove already reserved regions To: Nicolas Boichat , Rob Herring , Andre Przywara Cc: Frank Rowand , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Ian Campbell , Grant Likely , Stephen Boyd References: <20190703050827.173284-1-drinkcat@chromium.org> From: Jan Kiszka Message-ID: <12b02977-d038-8fc7-d61e-e694a6b90f7b@siemens.com> Date: Mon, 22 Mar 2021 08:58:34 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20190703050827.173284-1-drinkcat@chromium.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03.07.19 07:08, Nicolas Boichat wrote: > If the device tree is incorrectly configured, and attempts to > define a "no-map" reserved memory that overlaps with the kernel > data/code, the kernel would crash quickly after boot, with no > obvious clue about the nature of the issue. > > For example, this would happen if we have the kernel mapped at > these addresses (from /proc/iomem): > 40000000-41ffffff : System RAM > 40080000-40dfffff : Kernel code > 40e00000-411fffff : reserved > 41200000-413e0fff : Kernel data > > And we declare a no-map shared-dma-pool region at a fixed address > within that range: > mem_reserved: mem_region { > compatible = "shared-dma-pool"; > reg = <0 0x40000000 0 0x01A00000>; > no-map; > }; > > To fix this, when removing memory regions at early boot (which is > what "no-map" regions do), we need to make sure that the memory > is not already reserved. If we do, __reserved_mem_reserve_reg > will throw an error: > [ 0.000000] OF: fdt: Reserved memory: failed to reserve memory > for node 'mem_region': base 0x0000000040000000, size 26 MiB > and the code that will try to use the region should also fail, > later on. > > We do not do anything for non-"no-map" regions, as memblock > explicitly allows reserved regions to overlap, and the commit > that this fixes removed the check for that precise reason. > > Fixes: 094cb98179f19b7 ("of/fdt: memblock_reserve /memreserve/ regions in the case of partial overlap") > Signed-off-by: Nicolas Boichat > --- > drivers/of/fdt.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index cd17dc62a71980a..a1ded43fc332d0c 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -1138,8 +1138,16 @@ int __init __weak early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size) > int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base, > phys_addr_t size, bool nomap) > { > - if (nomap) > + if (nomap) { > + /* > + * If the memory is already reserved (by another region), we > + * should not allow it to be removed altogether. > + */ > + if (memblock_is_region_reserved(base, size)) > + return -EBUSY; > + > return memblock_remove(base, size); > + } > return memblock_reserve(base, size); > } > > Likely the wrong patch to blame but hopefully the right audience: I'm trying to migrate my RPi4 setup to mainline, and this commit breaks booting with TF-A (current master) in the loop. Error: [ 0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd083] [ 0.000000] Linux version 5.10.24+ (jan@md1f2u6c) (aarch64-linux-gnu-gcc (GNU Toolchain for the A-profile Architecture 9.2-2019.12 (arm-9.10)) 9.2.1 20191025, GNU ld (GNU Toolchain for the A-profile Architecture 9.2-2019.12 (arm-9.10)1 [ 0.000000] Machine model: Raspberry Pi 4 Model B Rev 1.1 [ 0.000000] efi: UEFI not found. [ 0.000000] OF: fdt: Reserved memory: failed to reserve memory for node 'atf@0': base 0x0000000000000000, size 0 MiB And then we hang later on when Linux does start to use that memory and seems to trigger an exception. Is there a bug in the upstream RPi4 DT? Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux