Re: [PATCH net-next v6 07/23] zinc: ChaCha20 ARM and ARM64 implementations

Ard Biesheuvel
2018-09-26T15:52:07Z

On Wed, 26 Sep 2018 at 17:50, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
>
> On Wed, Sep 26, 2018 at 5:45 PM Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> > So what you have in mind is something like calling simd_relax() every
> > 4096 bytes or so?
>
> That was actually pretty easy, putting together both of your suggestions:
>
> static inline bool chacha20_arch(struct chacha20_ctx *state, u8 *dst,
> u8 *src, size_t len,
> simd_context_t *simd_context)
> {
> while (len > PAGE_SIZE) {
> chacha20_arch(state, dst, src, PAGE_SIZE, simd_context);
> len -= PAGE_SIZE;
> src += PAGE_SIZE;
> dst += PAGE_SIZE;
> simd_relax(simd_context);
> }
> if (IS_ENABLED(CONFIG_KERNEL_MODE_NEON) && chacha20_use_neon &&
> len >= CHACHA20_BLOCK_SIZE * 3 && simd_use(simd_context))
> chacha20_neon(dst, src, len, state->key, state->counter);
> else
> chacha20_arm(dst, src, len, state->key, state->counter);
>
> state->counter[0] += (len + 63) / 64;
> return true;
> }

Nice one :-)

This works for me (but perhaps add a comment as well)