Re: [PATCH] x86/crypto: ghash: use C implementation for setkey()

["H. Peter Anvin" <hpa@zytor.com>]

On 03/27/2014 04:46 AM, Ard Biesheuvel wrote:
> On 27 March 2014 12:36, Herbert Xu <herbert@gondor.apana.org.au> wrote:
>> On Thu, Mar 27, 2014 at 12:29:00PM +0100, Ard Biesheuvel wrote:
>>> The GHASH setkey() function uses SSE registers but fails to call
>>> kernel_fpu_begin()/kernel_fpu_end(). Instead of adding these calls, and
>>> then having to deal with the restriction that they cannot be called from
>>> interrupt context, move the setkey() implementation to the C domain.
>>
>> Note that setkey cannot be called from interrupt context since
>> allocation/setkey is supposed to be slow-path material.
>>
>> But your approach is fine by me.
> 
> I agree that it makes little sense to call this from atomic context,
> but that still means (I think, but the x86 guys should confirm) that
> you are supposed to call kernel_fpu_begin() and kernel_fpu_end().
> 

Yes.  I'm suspecting calling kernel_fpu_begin() for a single GF
operation is probably not worth it, so I'm fine with reimplementing it
in integer logic.

Acked-by: H. Peter Anvin <hpa@linux.intel.com>

	-hpa