xxhash is currently implemented as a self-contained module in /lib.
This patch enables that module to be used as part of the generic kernel
crypto framework. It adds a simple wrapper to the 64bit version.

I've also added test vectors (with help from Nick Terrell). The upstream
xxhash code is tested by running hashing operation on random 222 byte
data with seed values of 0 and a prime number. The upstream test
suite can be found at https://github.com/Cyan4973/xxHash/blob/cf46e0c/xxhsum.c#L664



Essentially hashing is run on data of length 0,1,14,222 with the
aforementioned seed values 0 and prime 2654435761. The particular random
222 byte string was provided to me by Nick Terrell by reading
/dev/random and the checksums were calculated by the upstream xxsum
utility with the following bash script:

dd if=/dev/random of=TEST_VECTOR bs=1 count=222

for a in 0 1; do
	for l in 0 1 14 222; do
		for s in 0 2654435761; do
			echo algo $a length $l seed $s;
			head -c $l TEST_VECTOR | ~/projects/kernel/xxHash/xxhsum -H$a -s$s
		done
	done
done

This produces output as follows:

algo 0 length 0 seed 0
02cc5d05  stdin
algo 0 length 0 seed 2654435761
02cc5d05  stdin
algo 0 length 1 seed 0
25201171  stdin
algo 0 length 1 seed 2654435761
25201171  stdin
algo 0 length 14 seed 0
c1d95975  stdin
algo 0 length 14 seed 2654435761
c1d95975  stdin
algo 0 length 222 seed 0
b38662a6  stdin
algo 0 length 222 seed 2654435761
b38662a6  stdin
algo 1 length 0 seed 0
ef46db3751d8e999  stdin
algo 1 length 0 seed 2654435761
ac75fda2929b17ef  stdin
algo 1 length 1 seed 0
27c3f04c2881203a  stdin
algo 1 length 1 seed 2654435761
4a15ed26415dfe4d  stdin
algo 1 length 14 seed 0
3d33dc700231dfad  stdin
algo 1 length 14 seed 2654435761
ea5f7ddef9a64f80  stdin
algo 1 length 222 seed 0
5f3d3c08ec2bef34  stdin
algo 1 length 222 seed 2654435761
6a9df59664c7ed62  stdin

algo 1 is xx64 variant, algo 0 is the 32 bit variant which is currently
not hooked up.

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>