[RFC PATCH 6/6] riscv: Add BLAKE2s V implementation

[Conor Dooley]

On Tue, Sep 12, 2023 at 01:57:28PM +0200, Björn Töpel wrote:
> From: Björn Töpel <bjorn at rivosinc.com>
> 
> BLAKE2s is used in various places, most notably in Wireguard, and as
> of v5.17 in drivers/char/random.
> 
> Add a BLAKE2s implementation using the V-extension. This is a
> translation of the x86-64 AVX512 variant
> (arch/x86/crypto/blake2s-core.S) to the RISC-V V-extension.
> 
> The AVX512 variant requires registers >= 256b (ymm*), and hence this
> implementation requires a VLEN of >=256.
> 
> The implementation passes the kernel BLAKE2s selftest, and has been
> tested on spike and qemu.
> 
> Instruction-wise, the V-variant uses 60% less instructions than the
> generic, C-based, implementation.
> 
> Signed-off-by: Björn Töpel <bjorn at rivosinc.com>

>  arch/riscv/crypto/blake2s-v.S    | 164 +++++++++++++++++++++++++++++++


This file is currently being built for !RISCV_ISA_V, leading to build errors
for obvious reasons. Eg:
../arch/riscv/crypto/blake2s-v.S:62:2: error: instruction requires the following: 'V' (Vector Extension for Application Processors), 'Zve32x' or 'Zve64x' (Vector Extensions for Embedded Processors)

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