crypto: ghash - Add PCLMULQDQ accelerated implementation

PCLMULQDQ is used to accelerate the most time-consuming part of GHASH,
carry-less multiplication. More information about PCLMULQDQ can be
found at:

http://software.intel.com/en-us/articles/carry-less-multiplication-and-its-usage-for-computing-the-gcm-mode/

Because PCLMULQDQ changes XMM state, its usage must be enclosed with
kernel_fpu_begin/end, which can be used only in process context, the
acceleration is implemented as crypto_ahash. That is, request in soft
IRQ context will be defered to the cryptd kernel thread.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/include/crypto/cryptd.h b/include/crypto/cryptd.h
index 2f65a6e..1c96b25 100644
--- a/include/crypto/cryptd.h
+++ b/include/crypto/cryptd.h
@@ -39,6 +39,7 @@
 struct cryptd_ahash *cryptd_alloc_ahash(const char *alg_name,
 					u32 type, u32 mask);
 struct crypto_shash *cryptd_ahash_child(struct cryptd_ahash *tfm);
+struct shash_desc *cryptd_shash_desc(struct ahash_request *req);
 void cryptd_free_ahash(struct cryptd_ahash *tfm);
 
 #endif