From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1753665AbdF1CoN (ORCPT <rfc822;w@1wt.eu>);
        Tue, 27 Jun 2017 22:44:13 -0400
Received: from mail-qt0-f194.google.com ([209.85.216.194]:33840 "EHLO
        mail-qt0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752010AbdF1CoF (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 27 Jun 2017 22:44:05 -0400
Subject: Re: [PATCH] ARM: small correction to early_ioremap support
To: Russell King <linux@armlinux.org.uk>
Cc: Laura Abbott <labbott@redhat.com>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Nicolas Pitre <nicolas.pitre@linaro.org>,
        Jon Medhurst <tixy@linaro.org>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Kees Cook <keescook@chromium.org>, Marc Zyngier <marc.zyngier@arm.com>,
        "moderated list:ARM PORT" <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20170627005731.7869-1-opendmb@gmail.com>
From: Doug Berger <opendmb@gmail.com>
Message-ID: <fc934986-9ccf-01f0-0dbe-1db0a99680d3@gmail.com>
Date: Tue, 27 Jun 2017 19:44:02 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.1.1
MIME-Version: 1.0
In-Reply-To: <20170627005731.7869-1-opendmb@gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 06/26/2017 05:57 PM, Doug Berger wrote:
> The fixmap pages need to be on the same pmd page for the current
> implementation of arm early_fixmap.  A build time bug check is
> used to ensure that.  However, the worst case fixmap range is
> better represented by __end_of_fixed_addresses than by the value
> __end_of_early_ioremap_region.
I see now that only the early_ioremap portion of the fixmap needs to be
on the same pmd page and not the entire collection of fixmap pages.

Therefore the check against __end_of_early_ioremap_region is the correct
choice for this build time check.

Please disregard this patch.

Sorry for the confusion,
    Doug

> 
> Fixes: 2937367b8a4b ("ARM: add support for generic early_ioremap/early_memremap")
> Signed-off-by: Doug Berger <opendmb@gmail.com>
> ---
>  arch/arm/mm/mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 31af3cb59a60..74c0ed5c3b08 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -392,7 +392,7 @@ void __init early_fixmap_init(void)
>  	 * The early fixmap range spans multiple pmds, for which
>  	 * we are not prepared:
>  	 */
> -	BUILD_BUG_ON((__fix_to_virt(__end_of_early_ioremap_region) >> PMD_SHIFT)
> +	BUILD_BUG_ON((__fix_to_virt(__end_of_fixed_addresses) >> PMD_SHIFT)
>  		     != FIXADDR_TOP >> PMD_SHIFT);
>  
>  	pmd = fixmap_pmd(FIXADDR_TOP);
>