linux-kernel - Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}

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

Message-ID: <20160315082254.GE9136@infradead.org>
Date:	Tue, 15 Mar 2016 01:22:54 -0700
From:	Christoph Hellwig <hch@...radead.org>
To:	Christoph Hellwig <hch@...radead.org>,
	Dan Williams <dan.j.williams@...el.com>,
	Vinod Koul <vinod.koul@...el.com>,
	linux-renesas-soc@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dmaengine@...r.kernel.org" <dmaengine@...r.kernel.org>,
	iommu@...ts.linux-foundation.org, robin.murphy@....com,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	geert+renesas@...der.be, Linus Walleij <linus.walleij@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, linux-arch@...r.kernel.org
Subject: Re: [PATCH v5 3/9] dma-mapping: add dma_{map,unmap}_resource

On Fri, Mar 11, 2016 at 01:58:46PM +0100, Niklas S?derlund wrote:
> Without an IOMMU this is easy since the phys_addr_t and dma_addr_t are 
> the same and no special care is needed. However if you have a IOMMU you 
> need to map the DMA slave phys_addr_t to a dma_addr_t using something 
> like this. Is it not very similar to dma_map_single() where one maps 
> processor virtual memory (instead if MMIO) so that it can be used with 
> DMA slaves?

It's similar, but I don't think this actually works as a general case
as there are quite a few places that expect to be able to have a
struct page for a physical address.  We'd at least need a very careful
audit for that case.