[PATCH 02/20] lib/crypto: aes-xctr: Pass counter by value to aes_xctr_arch()

[Thomas Huth]

On 21/09/2026 07.08, Eric Biggers wrote:
> Update the calling convention for aes_xctr_arch() to pass the counter by
> value, then do the increment in generic code.  This aligns better with
> the x86_64 and arm64 assembly code for XCTR, which takes the counter by
> value and thus has to be paired with an increment in C code anyway.
> 
> Signed-off-by: Eric Biggers <ebiggers at kernel.org>
> ---
>   lib/crypto/aes.c | 6 ++++--
>   1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/crypto/aes.c b/lib/crypto/aes.c
> index f1549839b3de..22f096c50242 100644
> --- a/lib/crypto/aes.c
> +++ b/lib/crypto/aes.c
> @@ -1094,7 +1094,7 @@ static bool aes_ctr_arch(u8 *dst, const u8 *src, size_t len,
>   }
>   #endif
>   #ifndef aes_xctr_arch
> -static bool aes_xctr_arch(u8 *dst, const u8 *src, size_t len, u64 *ctr,
> +static bool aes_xctr_arch(u8 *dst, const u8 *src, size_t len, u64 ctr,
>   			  const u8 iv[AES_BLOCK_SIZE],
>   			  const struct aes_enckey *key)
>   {
> @@ -1150,8 +1150,10 @@ void aes_xctr(u8 *dst, const u8 *src, size_t len, u64 *ctr,
>   	__le64 aes_input[2];
>   	u8 keystream[AES_BLOCK_SIZE] __aligned(__alignof__(long));
>   
> -	if (likely(aes_xctr_arch(dst, src, len, ctr, iv, key.enc_key)))
> +	if (likely(aes_xctr_arch(dst, src, len, *ctr, iv, key.enc_key))) {
> +		*ctr += DIV_ROUND_UP(len, AES_BLOCK_SIZE);
>   		return;
> +	}
>   
>   	aes_input[1] = get_unaligned((const __le64 *)&iv[8]);
>   	/* Handle the full blocks. */

Reviewed-by: Thomas Huth <thuth at redhat.com>