AES iov optimization

[sef]

Summary

Right now, aesni_cipher_alloc does a bit of special-casing for CRYPTO_F_IOV, to not do any allocation if the first uio is large enough for the requested size. While working on ZFS crypto port, I ran into horrible performance because the code uses scatter-gather, and many of the times the data to encrypt was in the second entry. This code looks through the list, and tries to see if there is a single uio that can contain the requested data, and, if so, uses that.

This has a slight impact on the current consumers, in that the check is a little more complicated for the ones that use CRYPTO_F_IOV -- but none of them meet the criteria for testing more than one.

Test Plan

cryptocheck

[cem]

sys/crypto/aesni/aesni.c

407–408

This would be reduced to:

addr = crypto_contiguous_subsegment(crp->crp_flags, crp->crp_buf, enccrd->crd_skip, enccrd->crd_len);
if (addr != NULL) {
    *allocated = false;
    return (addr);
}

// was: alloc:
...

409–432

Like I mentioned in the other review, I think this is more broadly useful to OCF consumers than just aesni. E.g., armv8_crypto_cipher_alloc was basically copy-pasted from aesni and has the same issue. And the identical optimization can be applied to mbuf chains.

Given the general trend of OCF crypto_* methods that are agnostic to type, maybe it makes sense to just make this an OCF subroutine that operates generically, like crypto_copydata?

static inline void *
m_contiguous_subsegment(struct mbuf *m, size_t skip, size_t len)
{
        int rel_off;

        MPASS(skip <= INT_MAX);

        m = m_getptr(m, (int)skip, &rel_off);
        if (m == NULL)
                return (NULL);

        MPASS(rel_off >= 0);
        skip = rel_off;
        if (skip + len > m->m_len)
                return (NULL);
        return (mtod(m, char *) + skip);
}

static void *
cuio_contiguous_subsegment(struct uio *uio, size_t skip, size_t len)
{
        int rel_off, idx;

        MPASS(skip <= INT_MAX);
        idx = cuio_getptr(uio, (int)skip, &rel_off);
        if (idx < 0)
                return (NULL);

        MPASS(rel_off >= 0);
        skip = rel_off;
        if (skip + len > uio->uio_iov[idx].iov_len)
                return (NULL);
        return ((char *)uio->uio_iov[idx].iov_base + skip);
}

void *
crypto_contiguous_subsegment(int crpflags, void *crpbuf, size_t skip, size_t len)
{
        if ((flags & CRYPTO_F_IMBUF) != 0)
                return (m_contiguous_subsegment(crpbuf, off, size, out));
        else if ((flags & CRYPTO_F_IOV) != 0)
                return (cuio_contiguous_subsegment(crpbuf, off, size, out));
        else {
                MPASS((crp_flags & (CRYPTO_F_IMBUF | CRYPTO_F_IOV)) !=
                    (CRYPTO_F_IMBUF | CRYPTO_F_IOV));
                return ((char *)crpbuf + skip);
        }
}

(Either way, the poorly named cuio_getptr already does most of this logic for you.)

415

false for bool false values

[sef]

sys/crypto/aesni/aesni.c

409–432

I'm *perfectly* happy to have another version of it done. The existing one is a bit of a hack, and I just extended the hack for a case I cared about. I tried to touch the greater crypto code as minimally as possible, which means that I didn't refactor anything.

415

Easily enough done.

[sef]

Re-implemented per cem's feedback. Tested with cryptocheck.

[cem]

LGTM, thanks!