Re: [PATCH v2 06/18] crypto: rockchip: add fallback for cipher

John Keeping
2022-03-03T14:22:01Z

On Wed, Mar 02, 2022 at 09:11:01PM +0000, Corentin Labbe wrote:
> The hardware does not handle 0 size length request, let's add a
> fallback.
> Furthermore fallback will be used for all unaligned case the hardware
> cannot handle.
>
> Fixes: ce0183cb6464b ("crypto: rockchip - switch to skcipher API")
> Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
> ---
> drivers/crypto/rockchip/rk3288_crypto.h | 2 +
> .../crypto/rockchip/rk3288_crypto_skcipher.c | 97 ++++++++++++++++---
> 2 files changed, 86 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/crypto/rockchip/rk3288_crypto.h b/drivers/crypto/rockchip/rk3288_crypto.h
> index c919d9a43a08..8b1e15d8ddc6 100644
> --- a/drivers/crypto/rockchip/rk3288_crypto.h
> +++ b/drivers/crypto/rockchip/rk3288_crypto.h
> @@ -246,10 +246,12 @@ struct rk_cipher_ctx {
> struct rk_crypto_info *dev;
> unsigned int keylen;
> u8 iv[AES_BLOCK_SIZE];
> + struct crypto_skcipher *fallback_tfm;
> };
>
> struct rk_cipher_rctx {
> u32 mode;
> + struct skcipher_request fallback_req; // keep at the end
> };
>
> enum alg_type {
> diff --git a/drivers/crypto/rockchip/rk3288_crypto_skcipher.c b/drivers/crypto/rockchip/rk3288_crypto_skcipher.c
> index bbd0bf52bf07..bf9d398cc54c 100644
> --- a/drivers/crypto/rockchip/rk3288_crypto_skcipher.c
> +++ b/drivers/crypto/rockchip/rk3288_crypto_skcipher.c
> @@ -13,6 +13,63 @@
>
> #define RK_CRYPTO_DEC BIT(0)
>
> +static int rk_cipher_need_fallback(struct skcipher_request *req)
> +{
> + struct scatterlist *sgs, *sgd;
> +
> + if (!req->cryptlen)
> + return true;
> +
> + sgs = req->src;
> + while (sgs) {
> + if (!IS_ALIGNED(sgs->offset, sizeof(u32))) {
> + return true;
> + }
> + if (sgs->length % 16) {

Can this be relaxed to check for alignment to 4 rather than 16? That's
the requirement for programming the registers.

But I think this check is wrong in general as it doesn't account for
cryptlen; with fscrypt I'm seeing sgs->length == 255 but cryptlen == 16
so the hardware can be used but at the moment the fallback path is
triggered.