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=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 54DC9C433DB for ; Mon, 22 Mar 2021 18:11:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF2DF61998 for ; Mon, 22 Mar 2021 18:11:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230225AbhCVSKe (ORCPT ); Mon, 22 Mar 2021 14:10:34 -0400 Received: from lizzard.sbs.de ([194.138.37.39]:37808 "EHLO lizzard.sbs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230165AbhCVSKY (ORCPT ); Mon, 22 Mar 2021 14:10:24 -0400 Received: from mail2.sbs.de (mail2.sbs.de [192.129.41.66]) by lizzard.sbs.de (8.15.2/8.15.2) with ESMTPS id 12MIAD3O000529 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 22 Mar 2021 19:10:13 +0100 Received: from [167.87.37.70] ([167.87.37.70]) by mail2.sbs.de (8.15.2/8.15.2) with ESMTP id 12MI5CsM007874; Mon, 22 Mar 2021 19:05:12 +0100 Subject: Re: [PATCH] of/fdt: Make sure no-map does not remove already reserved regions From: Jan Kiszka To: Nicolas Boichat , Rob Herring , Andre Przywara , Phil Elwell 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> <12b02977-d038-8fc7-d61e-e694a6b90f7b@siemens.com> Message-ID: <5154396c-fffd-8e9d-3e2e-860fff35e9fc@siemens.com> Date: Mon, 22 Mar 2021 19:05:12 +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: <12b02977-d038-8fc7-d61e-e694a6b90f7b@siemens.com> 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 22.03.21 08:58, Jan Kiszka wrote: > 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? > FWIW, this is triggering the conflict: (arch/arm/boot/dts/bcm283x.dtsi) /* firmware-provided startup stubs live here, where the secondary CPUs are * spinning. */ /memreserve/ 0x00000000 0x00001000; I strongly suspect this is only needed in case of TF-A-free boot. With TF-A we have standard PCSI (my motivation to use TF-A in the first place) - and then this is in conflict with the firmware's reservation. Do we need separate DTs for this use case? Or should TF-A account for this? Jan -- Siemens AG, T RDA IOT Corporate Competence Center Embedded Linux