[PATCH v3 1/4] Wrap crc_t10dif function all to use crypto transform framework

[Tim Chen]

When CRC T10 DIF is calculated using the crypto transform framework, we
wrap the crc_t10dif function call to utilize it.  This allows us to
take advantage of any accelerated CRC T10 DIF transform that is
plugged into the crypto framework.

Signed-off-by: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
---
 crypto/Kconfig             |   9 ++++
 crypto/Makefile            |   1 +
 crypto/crct10dif.c         | 126 +++++++++++++++++++++++++++++++++++++++++++++
 include/linux/crc-t10dif.h |   5 ++
 lib/crc-t10dif.c           |  95 +++++++++++++++++++++++++++++++++-
 5 files changed, 234 insertions(+), 2 deletions(-)
 create mode 100644 crypto/crct10dif.c

diff --git a/crypto/Kconfig b/crypto/Kconfig
index 0e7a237..17b78e4 100644
--- a/crypto/Kconfig
+++ b/crypto/Kconfig
@@ -376,6 +376,15 @@ config CRYPTO_CRC32_PCLMUL
 	  which will enable any routine to use the CRC-32-IEEE 802.3 checksum
 	  and gain better performance as compared with the table implementation.
 
+config CRYPTO_CRCT10DIF
+	tristate "CRCT10DIF algorithm"
+	depends on CRC_T10DIF
+	select CRYPTO_HASH
+	help
+	  CRC T10 Data Integrity Field computation is being cast as
+	  a crypto transform.  This allows for faster crc t10 diff
+	  transforms to be used if they are available.
+
 config CRYPTO_GHASH
 	tristate "GHASH digest algorithm"
 	select CRYPTO_GF128MUL
diff --git a/crypto/Makefile b/crypto/Makefile
index a8e9b0f..62af87d 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_CRYPTO_ZLIB) += zlib.o
 obj-$(CONFIG_CRYPTO_MICHAEL_MIC) += michael_mic.o
 obj-$(CONFIG_CRYPTO_CRC32C) += crc32c.o
 obj-$(CONFIG_CRYPTO_CRC32) += crc32.o
+obj-$(CONFIG_CRYPTO_CRCT10DIF) += crct10dif.o
 obj-$(CONFIG_CRYPTO_AUTHENC) += authenc.o authencesn.o
 obj-$(CONFIG_CRYPTO_LZO) += lzo.o
 obj-$(CONFIG_CRYPTO_842) += 842.o
diff --git a/crypto/crct10dif.c b/crypto/crct10dif.c
new file mode 100644
index 0000000..246af93
--- /dev/null
+++ b/crypto/crct10dif.c
@@ -0,0 +1,126 @@
+/*
+ * Cryptographic API.
+ *
+ * T10 Data Integrity Field CRC16 Crypto Transform
+ *
+ * Copyright (C) 2013 Intel Corporation
+ * Author: Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/module.h>
+#include <linux/crc-t10dif.h>
+#include <crypto/internal/hash.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+
+struct chksum_desc_ctx {
+	__u16 crc;
+};
+
+/*
+ * Steps through buffer one byte at at time, calculates reflected
+ * crc using table.
+ */
+
+static int chksum_init(struct shash_desc *desc)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	ctx->crc = 0;
+
+	return 0;
+}
+
+static int chksum_update(struct shash_desc *desc, const u8 *data,
+			 unsigned int length)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	ctx->crc = crc_t10dif_generic(ctx->crc, data, length);
+	return 0;
+}
+
+static int chksum_final(struct shash_desc *desc, u8 *out)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	*(__u16 *)out = ctx->crc;
+	return 0;
+}
+
+static int __chksum_finup(__u16 *crcp, const u8 *data, unsigned int len,
+			u8 *out)
+{
+	*(__u16 *)out = crc_t10dif_generic(*crcp, data, len);
+	return 0;
+}
+
+static int chksum_finup(struct shash_desc *desc, const u8 *data,
+			unsigned int len, u8 *out)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	return __chksum_finup(&ctx->crc, data, len, out);
+}
+
+static int chksum_digest(struct shash_desc *desc, const u8 *data,
+			 unsigned int length, u8 *out)
+{
+	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);
+
+	return __chksum_finup(&ctx->crc, data, length, out);
+}
+
+static struct shash_alg alg = {
+	.digestsize		=	CRC_T10DIF_DIGEST_SIZE,
+	.init		=	chksum_init,
+	.update		=	chksum_update,
+	.final		=	chksum_final,
+	.finup		=	chksum_finup,
+	.digest		=	chksum_digest,
+	.descsize		=	sizeof(struct chksum_desc_ctx),
+	.base			=	{
+		.cra_name		=	"crct10dif",
+		.cra_driver_name	=	"crct10dif-generic",
+		.cra_priority		=	100,
+		.cra_blocksize		=	CRC_T10DIF_BLOCK_SIZE,
+		.cra_module		=	THIS_MODULE,
+	}
+};
+
+static int __init crct10dif_mod_init(void)
+{
+	int ret;
+
+	ret = crypto_register_shash(&alg);
+	return ret;
+}
+
+static void __exit crct10dif_mod_fini(void)
+{
+	crypto_unregister_shash(&alg);
+}
+
+module_init(crct10dif_mod_init);
+module_exit(crct10dif_mod_fini);
+
+MODULE_AUTHOR("Tim Chen <tim.c.chen@xxxxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("T10 DIF CRC calculation.");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/crc-t10dif.h b/include/linux/crc-t10dif.h
index a9c96d8..65ac583 100644
--- a/include/linux/crc-t10dif.h
+++ b/include/linux/crc-t10dif.h
@@ -3,6 +3,11 @@
 
 #include <linux/types.h>
 
+#define CRC_T10DIF_DIGEST_SIZE 2
+#define CRC_T10DIF_BLOCK_SIZE 1
+
+__u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer, size_t len);
+void crc_t10dif_update_lib(void);
 __u16 crc_t10dif(unsigned char const *, size_t);
 
 #endif
diff --git a/lib/crc-t10dif.c b/lib/crc-t10dif.c
index fbbd66e..e4409bb 100644
--- a/lib/crc-t10dif.c
+++ b/lib/crc-t10dif.c
@@ -11,6 +11,9 @@
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/crc-t10dif.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <crypto/hash.h>
 
 /* Table generated using the following polynomium:
  * x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
@@ -51,9 +54,11 @@ static const __u16 t10_dif_crc_table[256] = {
 	0xF0D8, 0x7B6F, 0x6C01, 0xE7B6, 0x42DD, 0xC96A, 0xDE04, 0x55B3
 };
 
-__u16 crc_t10dif(const unsigned char *buffer, size_t len)
+static struct crypto_shash *crct10dif_tfm;
+static bool init;
+
+__u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer, size_t len)
 {
-	__u16 crc = 0;
 	unsigned int i;
 
 	for (i = 0 ; i < len ; i++)
@@ -61,7 +66,93 @@ __u16 crc_t10dif(const unsigned char *buffer, size_t len)
 
 	return crc;
 }
+EXPORT_SYMBOL(crc_t10dif_generic);
+
+/*
+ * If we have defined faster crypto transform for CRC-T10DIF, use that instead.
+ * This allows us to plug in fast version of CRC-T10DIF when available.
+ */
+
+void crc_t10dif_update_lib()
+{
+	struct crypto_shash *new_tfm;
+
+	new_tfm = crypto_alloc_shash("crct10dif", 0, 0);
+	if (IS_ERR(new_tfm))
+		return;
+
+	if (init && crct10dif_tfm) {
+		/* We are using crct10dif_tfm, cannot switch it to new_tfm */
+		if (crypto_tfm_alg_priority(&new_tfm->base) >
+		    crypto_tfm_alg_priority(&crct10dif_tfm->base)) {
+			pr_info("%s should be loaded prior to initializing "
+				"crc-t10dif module.\n",
+				crypto_tfm_alg_driver_name(&new_tfm->base));
+		}
+		goto free_tfm;
+	}
+
+	if (crypto_tfm_alg_priority(&new_tfm->base) <= 100)
+		/* don't need to use crypto xform for generic algorithm */
+		goto free_tfm;
+
+	if (!crct10dif_tfm)
+		goto set_tfm;	
+
+	if (crypto_tfm_alg_priority(&new_tfm->base) <=
+	    crypto_tfm_alg_priority(&crct10dif_tfm->base))
+		goto free_tfm;
+
+	/* we haven't initialized this module and use crct10dif_tfm yet,
+	 * safe to free crct10dif_tfm and use a better algorithm
+	 */
+	crypto_free_shash(crct10dif_tfm);
+set_tfm:
+	crct10dif_tfm = new_tfm;
+	return;
+
+free_tfm:
+	crypto_free_shash(new_tfm);
+}
+EXPORT_SYMBOL(crc_t10dif_update_lib);
+
+__u16 crc_t10dif(const unsigned char *buffer, size_t len)
+{
+	struct {
+		struct shash_desc shash;
+		char ctx[2];
+	} desc;
+	int err;
+
+	if (unlikely(!init) || !crct10dif_tfm)
+		return crc_t10dif_generic(0, buffer, len);
+
+	desc.shash.tfm = crct10dif_tfm;
+	desc.shash.flags = 0;
+	*(__u16 *)desc.ctx = 0;
+
+	err = crypto_shash_update(&desc.shash, buffer, len);
+	BUG_ON(err);
+
+	return *(__u16 *)desc.ctx;
+}
 EXPORT_SYMBOL(crc_t10dif);
 
+static int __init crc_t10dif_mod_init(void)
+{
+	crc_t10dif_update_lib();
+	init = true;
+	return 0;
+}
+
+static void __exit crc_t10dif_mod_fini(void)
+{
+	if (crct10dif_tfm)
+		crypto_free_shash(crct10dif_tfm);
+}
+
+module_init(crc_t10dif_mod_init);
+module_exit(crc_t10dif_mod_fini);
+
 MODULE_DESCRIPTION("T10 DIF CRC calculation");
 MODULE_LICENSE("GPL");
-- 
1.7.11.7

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