From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754258AbdEIQ0D (ORCPT ); Tue, 9 May 2017 12:26:03 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:35512 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750805AbdEIQ0B (ORCPT ); Tue, 9 May 2017 12:26:01 -0400 Subject: Re: [PATCH V2] ARM: dts: bcm283x: Reserve first page for firmware To: Phil Elwell , Rob Herring , Mark Rutland , Russell King , Florian Fainelli , bcm-kernel-feedback-list@broadcom.com, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-rpi-kernel@lists.infradead.org References: From: Florian Fainelli Message-ID: Date: Tue, 9 May 2017 09:25:54 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/09/2017 02:04 AM, Phil Elwell wrote: > The Raspberry Pi startup stub files for multi-core BCM27XX processors > make the secondary CPUs spin until the corresponding mailbox is > written. These stubs are loaded at physical address 0x00000xxx (as seen > by the ARMs), but this page will be reused by the kernel unless it is > explicitly reserved, causing the waiting cores to execute random code. > > Use the /memreserve/ Device Tree directive to mark the first page as > off-limits to the kernel. This reserves a 4KB page here, is this good enough, or should we just go directly to the maximum page granule size possible on an ARM64/Linux system to be on the safe side? > > See: https://github.com/raspberrypi/linux/issues/1989 > > Signed-off-by: Phil Elwell > --- > > Changes in V2: > - Rebase against linux-next > - Drop downstream-only patch > > arch/arm/boot/dts/bcm283x.dtsi | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm/boot/dts/bcm283x.dtsi b/arch/arm/boot/dts/bcm283x.dtsi > index a3106aa..6d12c3e8 100644 > --- a/arch/arm/boot/dts/bcm283x.dtsi > +++ b/arch/arm/boot/dts/bcm283x.dtsi > @@ -3,6 +3,8 @@ > #include > #include > > +/memreserve/ 0x00000000 0x00001000; Can you put a comment above this /memreserve entry here to remind about what this is useful for? Thanks! > + > /* This include file covers the common peripherals and configuration between > * bcm2835 and bcm2836 implementations, leaving the CPU configuration to > * bcm2835.dtsi and bcm2836.dtsi. > -- Florian