[RFC PATCH] arm64: add support for AES in CCM mode using Crypto Extensions

Herbert Xu herbert at gondor.apana.org.au
Tue Feb 25 02:02:52 EST 2014

On Tue, Feb 11, 2014 at 09:21:45AM +0100, Ard Biesheuvel wrote:
> This adds support for a synchronous implementation of AES in CCM mode
> using ARMv8 Crypto Extensions, using NEON registers q0 - q5.
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel at linaro.org>
> ---
> Hi all,
> I am posting this for review/RFC. The main topic for feedback is the way
> I have used an inner blkcipher instance to process the encrypted + authenticated
> data.
> The point of having a dedicated module for synchronous ccm(aes) is the fact that
> mac80211 uses it for WPA2 CCMP en-/decryption, where it runs entirely in soft
> IRQ context. In this case, the performance improvement offered by dedicated AES
> instructions is likely wasted on stacking and unstacking the NEON register file,
> as the generic CCM operates on a single AES block at a time.
> Instead, this implementation interleaves the CTR and CBC modes at the round
> level, eliminating 50% of both the input and round key loads and (hopefully)
> eliminating pipeline stalls by operating on two AES blocks at a time.
> Tested with tcrypt, no performance numbers yet.

I think your idea definitely make sense, since we do the same
thing in aesni-intel.

It'll be interesting to see some numbers, especially if we could
compare this against the generic version that we talked about

Email: Herbert Xu <herbert at gondor.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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