lib: add rocksoft model crc64

The NVM Express specification extended data integrity fields to 64 bits
using the Rocksoft parameters. Add the poly to the crc64 table
generation, and provide a generic library routine implementing the
algorithm.

The Rocksoft 64-bit CRC model parameters are as follows:
    Poly: 0xAD93D23594C93659
    Initial value: 0xFFFFFFFFFFFFFFFF
    Reflected Input: True
    Reflected Output: True
    Xor Final: 0xFFFFFFFFFFFFFFFF

Since this model used reflected bits, the implementation generates the
reflected table so the result is ordered consistently.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20220303201312.3255347-6-kbusch@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 28 insertions, 0 deletions

diff --git a/lib/crc64.c b/lib/crc64.c
index 9f852a89ee2a..61ae8dfb6a1c 100644
--- a/lib/crc64.c
+++ b/lib/crc64.c
@@ -22,6 +22,13 @@
  * x^24 + x^23 + x^22 + x^21 + x^19 + x^17 + x^13 + x^12 + x^10 + x^9 +
  * x^7 + x^4 + x + 1
  *
+ * crc64rocksoft[256] table is from the Rocksoft specification polynomial
+ * defined as,
+ *
+ * x^64 + x^63 + x^61 + x^59 + x^58 + x^56 + x^55 + x^52 + x^49 + x^48 + x^47 +
+ * x^46 + x^44 + x^41 + x^37 + x^36 + x^34 + x^32 + x^31 + x^28 + x^26 + x^23 +
+ * x^22 + x^19 + x^16 + x^13 + x^12 + x^10 + x^9 + x^6 + x^4 + x^3 + 1
+ *
  * Copyright 2018 SUSE Linux.
  *   Author: Coly Li <colyli@suse.de>
  */
@@ -55,3 +62,24 @@ u64 __pure crc64_be(u64 crc, const void *p, size_t len)
 	return crc;
 }
 EXPORT_SYMBOL_GPL(crc64_be);
+
+/**
+ * crc64_rocksoft_generic - Calculate bitwise Rocksoft CRC64
+ * @crc: seed value for computation. 0 for a new CRC calculation, or the
+ * 	 previous crc64 value if computing incrementally.
+ * @p: pointer to buffer over which CRC64 is run
+ * @len: length of buffer @p
+ */
+u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len)
+{
+	const unsigned char *_p = p;
+	size_t i;
+
+	crc = ~crc;
+
+	for (i = 0; i < len; i++)
+		crc = (crc >> 8) ^ crc64rocksofttable[(crc & 0xff) ^ *_p++];
+
+	return ~crc;
+}
+EXPORT_SYMBOL_GPL(crc64_rocksoft_generic);