linux-kernel - Re: [PATCH v5 4/4] crypto: Add Allwinner Security System crypto accelerator

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Message-ID: <20141031081803.GA8012@gondor.apana.org.au>
Date:	Fri, 31 Oct 2014 16:18:03 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Maxime Ripard <maxime.ripard@...e-electrons.com>
Cc:	Corentin LABBE <clabbe.montjoie@...il.com>, robh+dt@...nel.org,
	pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	linux@....linux.org.uk, davem@...emloft.net,
	grant.likely@...aro.org, akpm@...ux-foundation.org,
	gregkh@...uxfoundation.org, joe@...ches.com,
	mchehab@....samsung.com, crope@....fi, devicetree@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-crypto@...r.kernel.org, linux-sunxi@...glegroups.com
Subject: Re: [PATCH v5 4/4] crypto: Add Allwinner Security System crypto
 accelerator

On Fri, Oct 31, 2014 at 09:13:23AM +0100, Maxime Ripard wrote:
>
> I don't understand here. Why would other drivers *not* being affected?
> 
> If the scatter list passed by AF_ALG can be in highmem, I guess it's
> the case for every driver out there. Almost every kernel code I've
> seen so far makes the assumption that the memory it has is mapped and
> accessible.
> 
> Somehow, it's the driver's fault now, and not the part of kernel that
> actually does the allocation?

If you are implementing a crypto driver that is meant to handle
requests from the crypto API then yes you need to handle highmem.

As I said if enough drivers are unable to address highmem and
require copying/software fallbacks then we could provide this
through the API and the driver would then only need to declare
its lack of highmem support or use a helper.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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