linux-kernel - Re: [PATCH v2] hwmon: xgene: access mailbox as RAM

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Fri, 9 Sep 2016 14:56:53 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Hoan Tran <hotran@....com>, Jean Delvare <jdelvare@...e.com>,
        Jonathan Corbet <corbet@....net>,
        Rob Herring <robh+dt@...nel.org>,
        Jassi Brar <jassisinghbrar@...il.com>,
        Ashwin Chaugule <ashwin.chaugule@...aro.org>,
        Duc Dang <dhdang@....com>, Loc Ho <lho@....com>,
        linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Devicetree List <devicetree@...r.kernel.org>
Subject: Re: [PATCH v2] hwmon: xgene: access mailbox as RAM

On Fri, Sep 09, 2016 at 10:10:45PM +0200, Arnd Bergmann wrote:
> The newly added hwmon driver fails to build in an allmodconfig
> kernel:
> 
>       ERROR: "memblock_is_memory" [drivers/hwmon/xgene-hwmon.ko] undefined!
> 
> According to comments in the code, the mailbox is a shared memory region,
> not a set of MMIO registers, so we should use memremap() for mapping it
> instead of ioremap or acpi_os_ioremap, and pointer dereferences instead
> of readl/writel.
> 
> The driver already uses plain kernel pointers, so it's a bit unusual
> to work with functions that operate on __iomem pointers, and this
> fixes that part too.
> 
> I'm using READ_ONCE/WRITE_ONCE here to keep the existing behavior
> regarding the ordering of the accesses from the CPU, but note that
> there are no barriers (also unchanged from before).
> 
> I'm also keeping the endianess behavior, though I'm unsure whether
> the message data was supposed to be in LE32 format in the first
> place, it's possible this was meant to be interpreted as a byte
> stream instead.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Applied after 's/endianess/endianness/' to make checkpatch happy.

Thanks,
Guenter