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From: Ard Biesheuvel <ardb@kernel.org>
Date: Thu, 11 Jan 2024 17:35:02 +0100
Message-ID: <CAMj1kXHBNe-CaFpWAxeWCw74vG8vwne-VOV6R4O+B=b7pcxiFQ@mail.gmail.com>
Subject: Re: [PATCH 4/8] crypto: arm64/aes-ccm - Replace bytewise tail
 handling with NEON permute
To: Ard Biesheuvel <ardb+git@google.com>
Cc: linux-crypto@vger.kernel.org, ebiggers@kernel.org, 
	herbert@gondor.apana.org.au
Content-Type: text/plain; charset="UTF-8"

On Thu, 11 Jan 2024 at 13:33, Ard Biesheuvel <ardb+git@google.com> wrote:
>
> From: Ard Biesheuvel <ardb@kernel.org>
>
> Implement the CCM tail handling using a single sequence that uses
> permute vectors and overlapping loads and stores, rather than going over
> the tail byte by byte in a loop, and using scalar operations. This is
> more efficient, even though the measured speedup is only around 1-2% on
> the CPUs I have tried.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  arch/arm64/crypto/aes-ce-ccm-core.S | 59 +++++++++++++-------
>  arch/arm64/crypto/aes-ce-ccm-glue.c | 20 +++----
>  2 files changed, 48 insertions(+), 31 deletions(-)
>
...

The hunks below don't belong here: they were supposed to be squashed
into the previous patch.

I will fix that up for the next revision.


> diff --git a/arch/arm64/crypto/aes-ce-ccm-glue.c b/arch/arm64/crypto/aes-ce-ccm-glue.c
> index 2f4e6a318fcd..4710e59075f5 100644
> --- a/arch/arm64/crypto/aes-ce-ccm-glue.c
> +++ b/arch/arm64/crypto/aes-ce-ccm-glue.c
> @@ -181,16 +181,16 @@ static int ccm_encrypt(struct aead_request *req)
>                 if (walk.nbytes == walk.total)
>                         tail = 0;
>
> -               if (unlikely(walk.total < AES_BLOCK_SIZE))
> -                       src = dst = memcpy(buf + sizeof(buf) - walk.total,
> -                                          src, walk.total);
> +               if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
> +                       src = dst = memcpy(&buf[sizeof(buf) - walk.nbytes],
> +                                          src, walk.nbytes);
>
>                 ce_aes_ccm_encrypt(dst, src, walk.nbytes - tail,
>                                    ctx->key_enc, num_rounds(ctx),
>                                    mac, walk.iv);
>
> -               if (unlikely(walk.total < AES_BLOCK_SIZE))
> -                       memcpy(walk.dst.virt.addr, dst, walk.total);
> +               if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
> +                       memcpy(walk.dst.virt.addr, dst, walk.nbytes);
>
>                 if (walk.nbytes == walk.total)
>                         ce_aes_ccm_final(mac, orig_iv, ctx->key_enc, num_rounds(ctx));
> @@ -248,16 +248,16 @@ static int ccm_decrypt(struct aead_request *req)
>                 if (walk.nbytes == walk.total)
>                         tail = 0;
>
> -               if (unlikely(walk.total < AES_BLOCK_SIZE))
> -                       src = dst = memcpy(buf + sizeof(buf) - walk.total,
> -                                          src, walk.total);
> +               if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
> +                       src = dst = memcpy(&buf[sizeof(buf) - walk.nbytes],
> +                                          src, walk.nbytes);
>
>                 ce_aes_ccm_decrypt(dst, src, walk.nbytes - tail,
>                                    ctx->key_enc, num_rounds(ctx),
>                                    mac, walk.iv);
>
> -               if (unlikely(walk.total < AES_BLOCK_SIZE))
> -                       memcpy(walk.dst.virt.addr, dst, walk.total);
> +               if (unlikely(walk.nbytes < AES_BLOCK_SIZE))
> +                       memcpy(walk.dst.virt.addr, dst, walk.nbytes);
>
>                 if (walk.nbytes == walk.total)
>                         ce_aes_ccm_final(mac, orig_iv, ctx->key_enc, num_rounds(ctx));
> --
> 2.43.0.275.g3460e3d667-goog
>