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/crypto/Kconfig b/crypto/Kconfig
index 26b5dd0..fd68711 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -440,6 +440,14 @@
 	  See also:
 	  <http://planeta.terra.com.br/informatica/paulobarreto/WhirlpoolPage.html>
 
+config CRYPTO_GHASH_CLMUL_NI_INTEL
+	tristate "GHASH digest algorithm (CLMUL-NI accelerated)"
+	select CRYPTO_SHASH
+	select CRYPTO_CRYPTD
+	help
+	  GHASH is message digest algorithm for GCM (Galois/Counter Mode).
+	  The implementation is accelerated by CLMUL-NI of Intel.
+
 comment "Ciphers"
 
 config CRYPTO_AES