On 01.05.2014 18:51, Ard Biesheuvel wrote:
> The Crypto Extensions based SHA1 implementation uses the NEON register file,
> and hence runs with preemption disabled. This patch adds a TIF_NEED_RESCHED
> check to its inner loop so we at least give up the CPU voluntarily when we
> are running in process context and have been tagged for preemption by the
> scheduler.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheu...@linaro.org>
> ---
<snip>
> @@ -42,6 +42,7 @@ static int sha1_update(struct shash_desc *desc, const u8
> *data,
> sctx->count += len;
>
> if ((partial + len) >= SHA1_BLOCK_SIZE) {
> + struct thread_info *ti = NULL;
> int blocks;
>
> if (partial) {
> @@ -52,16 +53,30 @@ static int sha1_update(struct shash_desc *desc, const u8
> *data,
> len -= p;
> }
>
> + /*
> + * Pass current's thread info pointer to sha1_ce_transform()
> + * below if we want it to play nice under preemption.
> + */
> + if ((IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY) ||
> + IS_ENABLED(CONFIG_PREEMPT)) && !in_interrupt())
> + ti = current_thread_info();
> +
> blocks = len / SHA1_BLOCK_SIZE;
> len %= SHA1_BLOCK_SIZE;
>
> - kernel_neon_begin_partial(16);
> - sha1_ce_transform(blocks, data, sctx->state,
> - partial ? sctx->buffer : NULL, 0);
> - kernel_neon_end();
> + do {
> + int rem;
> +
> + kernel_neon_begin_partial(16);
> + rem = sha1_ce_transform(blocks, data, sctx->state,
> + partial ? sctx->buffer : NULL,
> + 0, ti);
> + kernel_neon_end();
>
> - data += blocks * SHA1_BLOCK_SIZE;
> - partial = 0;
> + data += (blocks - rem) * SHA1_BLOCK_SIZE;
> + blocks = rem;
> + partial = 0;
> + } while (unlikely(ti && blocks > 0));
> }
> if (len)
> memcpy(sctx->buffer + partial, data, len);
> @@ -94,6 +109,7 @@ static int sha1_finup(struct shash_desc *desc, const u8
> *data,
> unsigned int len, u8 *out)
> {
> struct sha1_state *sctx = shash_desc_ctx(desc);
> + struct thread_info *ti = NULL;
> __be32 *dst = (__be32 *)out;
> int blocks;
> int i;
> @@ -111,9 +127,20 @@ static int sha1_finup(struct shash_desc *desc, const u8
> *data,
> */
> blocks = len / SHA1_BLOCK_SIZE;
>
> - kernel_neon_begin_partial(16);
> - sha1_ce_transform(blocks, data, sctx->state, NULL, len);
> - kernel_neon_end();
> + if ((IS_ENABLED(CONFIG_PREEMPT_VOLUNTARY) ||
> + IS_ENABLED(CONFIG_PREEMPT)) && !in_interrupt())
> + ti = current_thread_info();
> +
> + do {
> + int rem;
> +
> + kernel_neon_begin_partial(16);
> + rem = sha1_ce_transform(blocks, data, sctx->state,
> + NULL, len, ti);
> + kernel_neon_end();
> + data += (blocks - rem) * SHA1_BLOCK_SIZE;
> + blocks = rem;
> + } while (unlikely(ti && blocks > 0));
>
These seem to be similar, how about renaming assembly function to
__sha1_ce_transform
and moving this loop to new sha1_ce_transform.
Otherwise, patches looks good.
-Jussi
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