linux-kernel - Re: dma_unmap_single() lacking cache sync on some archs?

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-next>] [day] [month] [year] [list]

Message-ID: <4E81BDEE.2080601@enea.com>
Date:	Tue, 27 Sep 2011 14:13:34 +0200
From:	Arvid Brodin <arvid.brodin@...a.com>
To:	<linux-kernel@...r.kernel.org>
CC:	<linux-embedded@...r.kernel.org>,
	Hans-Christian Egtvedt <egtvedt@...fundet.no>,
	Haavard Skinnemoen <hskinnemoen@...il.com>, <arnd@...db.de>
Subject: Re: dma_unmap_single() lacking cache sync on some archs?

[Resending with CC to affected parties]

Hi,

I would expect cache synchronization for DMA_TO_DEVICE and DMA_BIDIRECTIONAL
when dma_map_single() is called, and for DMA_FROM_DEVICE and DMA_BIDIRECTIONAL
when dma_unmap_single() is called.

However, on some architechtures (at least avr32, blackfin, ...), cache
synchronization only happens when dma_map_single() is called (and then
irrespective of DMA direction). dma_unmap_single() is a no-op for these archs.

See e.g. http://lxr.linux.no/#linux+v3.0.4/arch/avr32/include/asm/dma-mapping.h#L117

Isn't this a bug?

(Please CC me in responses.)

-- 
Arvid Brodin
Enea Services Stockholm AB

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/