This patch adds the functions needed to create and use shash
spawns, i.e., to use shash algorithms in a template.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

This patch adds shash_instance and the associated alloc/free
functions.  This is meant to be an instance that with a shash
algorithm under it.  Note that the instance itself doesn't have
to be shash.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

This patch allows shash algorithms to be used through the old hash
interface.  This is a transitional measure so we can convert the
underlying algorithms to shash before converting the users across.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

It is often useful to save the partial state of a hash function
so that it can be used as a base for two or more computations.

The most prominent example is HMAC where all hashes start from
a base determined by the key.  Having an import/export interface
means that we only have to compute that base once rather than
for each message.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

The shash interface replaces the current synchronous hash interface.
It improves over hash in two ways.  Firstly shash is reentrant,
meaning that the same tfm may be used by two threads simultaneously
as all hashing state is stored in a local descriptor.

The other enhancement is that shash no longer takes scatter list
entries.  This is because shash is specifically designed for
synchronous algorithms and as such scatter lists are unnecessary.

All existing hash users will be converted to shash once the
algorithms have been completely converted.

There is also a new finup function that combines update with final.
This will be extended to ahash once the algorithm conversion is
done.

This is also the first time that an algorithm type has their own
registration function.  Existing algorithm types will be converted
to this way in due course.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

All new crypto interfaces should go into individual files as much
as possible in order to ensure that crypto.h does not collapse under
its own weight.

This patch moves the ahash code into crypto/hash.h and crypto/internal/hash.h
respectively.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

This patch adds the walking helpers for hash algorithms akin to
those of block ciphers.  This is a necessary step before we can
reimplement existing hash algorithms using the new ahash interface.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>