[PATCH] hash: Kconfig option for SHA512 hardware acceleration

[Joel Stanley]

On Fri, 14 May 2021 at 09:12, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> Commit a479f103dc1c ("hash: Allow for SHA512 hardware implementations")
> defined function definitions for hardware accelerated SHA384 and SHA512.
> If CONFIG_SHA_HW_ACCEL=y, these functions are used.
>
> We already have boards using CONFIG_SHA_HW_ACCEL=y but none implements the
> new functions hw_sha384() and hw_sha512().
>
> For implementing the EFI TCG2 protocol we need SHA384 and SHA512. The
> missing hardware acceleration functions lead to build errors on boards like
> peach-pi_defconfig.
>
> Introduce a new Kconfig symbol CONFIG_SHA512_HW_ACCEL to control if the
> functions hw_sha384() and hw_sha512() shall be used to implement the SHA384
> and SHA512 algorithms.
>
> Fixes: a479f103dc1c ("hash: Allow for SHA512 hardware implementations")
> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> ---
> This patch replaces
> hash: revert Allow for SHA512 hardware implementations
> https://lists.denx.de/pipermail/u-boot/2021-May/449648.html
> https://patchwork.ozlabs.org/project/uboot/patch/20210512170040.137058-1-xypron.glpk@gmx.de/

This looks to be a good compromise. Thanks for fixing it.

Reviewed-by: Joel Stanley <joel at jms.id.au>

The CONFIG maze that is the hash acceleration code could do with some
overarching cleanup at some point.


> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -389,21 +389,32 @@ config SHA384
>           (digest).
>
>  config SHA_HW_ACCEL
> -       bool "Enable hashing using hardware"
> +       bool "Enable hardware acceleration for SHA hash functions"
>         help
> -         This option enables hardware acceleration for SHA hashing.
> -         This affects the 'hash' command and also the hash_lookup_algo()
> -         function.
> +         This option enables hardware acceleration for the SHA1 and SHA256
> +         hashing algorithms. This affects the 'hash' command and also the
> +         hash_lookup_algo() function.
> +
> +if SHA_HW_ACCEL
> +
> +config SHA512_HW_ACCEL
> +       bool "Enable hardware acceleration for SHA512"
> +       depends on SHA512_ALGO

This dependency is new, does it make sense? We don't have an
equivalent one for SHA_HW_ACCEL, but perhaps we should introduce one?

> +       help
> +         This option enables hardware acceleration for the SHA384 andSHA512

Nit: there's a missing space after "and" here.

Perhaps you could add to the help text that this option should be
disabled if the platform requires SHA512 support but does not have
hardware acceleration.

> +         hashing algorithms. This affects the 'hash' command and also the
> +         hash_lookup_algo() function.
>
>  config SHA_PROG_HW_ACCEL
>         bool "Enable Progressive hashing support using hardware"
> -       depends on SHA_HW_ACCEL
>         help
>           This option enables hardware-acceleration for SHA progressive
>           hashing.
>           Data can be streamed in a block at a time and the hashing is
>           performed in hardware.
>
> +endif
> +
>  config MD5
>         bool "Support MD5 algorithm"
>         help
> --
> 2.30.2
>