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Date:   Fri, 16 Apr 2021 21:30:10 +1000
From:   Herbert Xu <herbert@gondor.apana.org.au>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     linux-crypto@vger.kernel.org
Subject: Re: [PATCH] crypto: arm64/aes-ce - deal with oversight in new CTR
 carry code
Message-ID: <20210416113010.GE16633@gondor.apana.org.au>
References: <20210406142523.1101817-1-ardb@kernel.org>
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On Tue, Apr 06, 2021 at 04:25:23PM +0200, Ard Biesheuvel wrote:
> The new carry handling code in the CTR driver can deal with a carry
> occurring in the 4x/5x parallel code path, by using a computed goto to
> jump into the carry sequence at the right place as to only apply the
> carry to a subset of the blocks being processed.
> 
> If the lower half of the counter wraps and ends up at exactly 0x0, a
> carry needs to be applied to the counter, but not to the counter values
> taken for the 4x/5x parallel sequence. In this case, the computed goto
> skips all register assignments, and branches straight to the jump
> instruction that gets us back to the fast path. This produces the
> correct result, but due to the fact that this branch target does not
> carry the correct BTI annotation, this fails when BTI is enabled.
> 
> Let's omit the computed goto entirely in this case, and jump straight
> back to the fast path after applying the carry to the main counter.
> 
> Fixes: 5318d3db465d ("crypto: arm64/aes-ctr - improve tail handling")
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  arch/arm64/crypto/aes-modes.S | 1 +
>  1 file changed, 1 insertion(+)

Patch applied.  Thanks.
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt