[PATCHv3 05/10] lib: add rocksoft model crc64

Keith Busch
2022-02-22T16:32:46Z

The NVM Express specification extended data integrity fields to 64 bits
using the Rocksoft^TM 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.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
include/linux/crc64.h | 2 ++
lib/crc64.c | 26 ++++++++++++++++++++++
lib/gen_crc64table.c | 51 +++++++++++++++++++++++++++++++++----------
3 files changed, 68 insertions(+), 11 deletions(-)

diff --git a/include/linux/crc64.h b/include/linux/crc64.h
index c756e65a1b58..9480f38cc7cf 100644
--- a/include/linux/crc64.h
+++ b/include/linux/crc64.h
@@ -8,4 +8,6 @@
#include <linux/types.h>

u64 __pure crc64_be(u64 crc, const void *p, size_t len);
+u64 __pure crc64_rocksoft_generic(u64 crc, const void *p, size_t len);
+
#endif /* _LINUX_CRC64_H */
diff --git a/lib/crc64.c b/lib/crc64.c
index 9f852a89ee2a..80072fa007a9 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 +62,22 @@ 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. (u64)~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;
+
+ for (i = 0; i < len; i++)
+ crc = (crc >> 8) ^ crc64rocksofttable[(crc & 0xff) ^ *_p++];
+
+ return crc ^ (u64)~0;
+}
+EXPORT_SYMBOL_GPL(crc64_rocksoft_generic);
diff --git a/lib/gen_crc64table.c b/lib/gen_crc64table.c
index 094b43aef8db..55e222acd0b8 100644
--- a/lib/gen_crc64table.c
+++ b/lib/gen_crc64table.c
@@ -17,10 +17,30 @@
#include <stdio.h>

#define CRC64_ECMA182_POLY 0x42F0E1EBA9EA3693ULL
+#define CRC64_ROCKSOFT_POLY 0x9A6C9329AC4BC9B5ULL

static uint64_t crc64_table[256] = {0};
+static uint64_t crc64_rocksoft_table[256] = {0};

-static void generate_crc64_table(void)
+static void generate_reflected_crc64_table(uint64_t table[256], uint64_t poly)
+{
+ uint64_t i, j, c, crc;
+
+ for (i = 0; i < 256; i++) {
+ crc = 0ULL;
+ c = i;
+
+ for (j = 0; j < 8; j++) {
+ if ((crc ^ (c >> j)) & 1)
+ crc = (crc >> 1) ^ poly;
+ else
+ crc >>= 1;
+ }
+ table[i] = crc;
+ }
+}
+
+static void generate_crc64_table(uint64_t table[256], uint64_t poly)
{
uint64_t i, j, c, crc;

@@ -30,26 +50,22 @@ static void generate_crc64_table(void)

for (j = 0; j < 8; j++) {
if ((crc ^ c) & 0x8000000000000000ULL)
- crc = (crc << 1) ^ CRC64_ECMA182_POLY;
+ crc = (crc << 1) ^ poly;
else
crc <<= 1;
c <<= 1;
}

- crc64_table[i] = crc;
+ table[i] = crc;
}
}

-static void print_crc64_table(void)
+static void output_table(uint64_t table[256])
{
int i;

- printf("/* this file is generated - do not edit */\n\n");
- printf("#include <linux/types.h>\n");
- printf("#include <linux/cache.h>\n\n");
- printf("static const u64 ____cacheline_aligned crc64table[256] = {\n");
for (i = 0; i < 256; i++) {
- printf("\t0x%016" PRIx64 "ULL", crc64_table[i]);
+ printf("\t0x%016" PRIx64 "ULL", table[i]);
if (i & 0x1)
printf(",\n");
else
@@ -58,9 +74,22 @@ static void print_crc64_table(void)
printf("};\n");
}

+static void print_crc64_tables(void)
+{
+ printf("/* this file is generated - do not edit */\n\n");
+ printf("#include <linux/types.h>\n");
+ printf("#include <linux/cache.h>\n\n");
+ printf("static const u64 ____cacheline_aligned crc64table[256] = {\n");
+ output_table(crc64_table);
+
+ printf("\nstatic const u64 ____cacheline_aligned crc64rocksofttable[256] = {\n");
+ output_table(crc64_rocksoft_table);
+}
+
int main(int argc, char *argv[])
{
- generate_crc64_table();
- print_crc64_table();
+ generate_crc64_table(crc64_table, CRC64_ECMA182_POLY);
+ generate_reflected_crc64_table(crc64_rocksoft_table, CRC64_ROCKSOFT_POLY);
+ print_crc64_tables();
return 0;
}
--
2.25.4