Re: [PATCH 1/3] crypto: x86/aesni - Refactor the common address alignment code

[Eric Biggers]

On Mon, Sep 25, 2023 at 08:17:50AM -0700, Chang S. Bae wrote:
> The address alignment code has been duplicated for each mode. Instead
> of duplicating the same code, refactor the alignment code and simplify
> the alignment helpers.
> 
> Suggested-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
> Cc: linux-crypto@xxxxxxxxxxxxxxx
> Cc: x86@xxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Link: https://lore.kernel.org/all/20230526065414.GB875@sol.localdomain/
> ---
>  arch/x86/crypto/aesni-intel_glue.c | 26 ++++++++++----------------
>  1 file changed, 10 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
> index 39d6a62ac627..241d38ae1ed9 100644
> --- a/arch/x86/crypto/aesni-intel_glue.c
> +++ b/arch/x86/crypto/aesni-intel_glue.c
> @@ -80,6 +80,13 @@ struct gcm_context_data {
>  	u8 hash_keys[GCM_BLOCK_LEN * 16];
>  };
>  
> +static inline void *aes_align_addr(void *addr)
> +{
> +	if (crypto_tfm_ctx_alignment() >= AESNI_ALIGN)
> +		return addr;
> +	return PTR_ALIGN(addr, AESNI_ALIGN);
> +}
> +
>  asmlinkage int aesni_set_key(struct crypto_aes_ctx *ctx, const u8 *in_key,
>  			     unsigned int key_len);
>  asmlinkage void aesni_enc(const void *ctx, u8 *out, const u8 *in);
> @@ -201,32 +208,19 @@ static __ro_after_init DEFINE_STATIC_KEY_FALSE(gcm_use_avx2);
>  static inline struct
>  aesni_rfc4106_gcm_ctx *aesni_rfc4106_gcm_ctx_get(struct crypto_aead *tfm)
>  {
> -	unsigned long align = AESNI_ALIGN;
> -
> -	if (align <= crypto_tfm_ctx_alignment())
> -		align = 1;
> -	return PTR_ALIGN(crypto_aead_ctx(tfm), align);
> +	return (struct aesni_rfc4106_gcm_ctx *)aes_align_addr(crypto_aead_ctx(tfm));
>  }
>  
>  static inline struct
>  generic_gcmaes_ctx *generic_gcmaes_ctx_get(struct crypto_aead *tfm)
>  {
> -	unsigned long align = AESNI_ALIGN;
> -
> -	if (align <= crypto_tfm_ctx_alignment())
> -		align = 1;
> -	return PTR_ALIGN(crypto_aead_ctx(tfm), align);
> +	return (struct generic_gcmaes_ctx *)aes_align_addr(crypto_aead_ctx(tfm));
>  }
>  #endif
>  
>  static inline struct crypto_aes_ctx *aes_ctx(void *raw_ctx)
>  {
> -	unsigned long addr = (unsigned long)raw_ctx;
> -	unsigned long align = AESNI_ALIGN;
> -
> -	if (align <= crypto_tfm_ctx_alignment())
> -		align = 1;
> -	return (struct crypto_aes_ctx *)ALIGN(addr, align);
> +	return (struct crypto_aes_ctx *)aes_align_addr(raw_ctx);
>  }

The casts can be dropped, since aes_align_addr() returns 'void *'.

- Eric