crc32: bolt on crc32c

Reuse the existing crc32 code to stamp out a crc32c implementation.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Bob Pearson <rpearson@systemfabricworks.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 95 insertions, 34 deletions

diff --git a/lib/Kconfig b/lib/Kconfig
index d5a86aa441ac..6d7ce4b138c4 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -61,14 +61,14 @@ config CRC_ITU_T
           functions require M here.
 
 config CRC32
-        tristate "CRC32 functions"
+        tristate "CRC32/CRC32c functions"
         default y
         select BITREVERSE
         help
           This option is provided for the case where no in-kernel-tree
-          modules require CRC32 functions, but a module built outside the
-          kernel tree does. Such modules that use library CRC32 functions
-          require M here.
+          modules require CRC32/CRC32c functions, but a module built outside
+          the kernel tree does. Such modules that use library CRC32/CRC32c
+          functions require M here.
 
 config CRC32_SELFTEST
         bool "CRC32 perform self test on init"
diff --git a/lib/crc32.c b/lib/crc32.c
index a1a5145a93ba..87678dd1141e 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -46,7 +46,7 @@
 #include "crc32table.h"
 
 MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
-MODULE_DESCRIPTION("Ethernet CRC32 calculations");
+MODULE_DESCRIPTION("Various CRC32 calculations");
 MODULE_LICENSE("GPL");
 
 #if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
@@ -135,45 +135,66 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
  * @p: pointer to buffer over which CRC is run
  * @len: length of buffer @p
  */
-u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
+                                          size_t len, const u32 (*tab)[256],
+                                          u32 polynomial)
 {
 #if CRC_LE_BITS == 1
         int i;
         while (len--) {
                 crc ^= *p++;
                 for (i = 0; i < 8; i++)
-                        crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
+                        crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
         }
 # elif CRC_LE_BITS == 2
         while (len--) {
                 crc ^= *p++;
-                crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
-                crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
-                crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
-                crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
+                crc = (crc >> 2) ^ tab[0][crc & 3];
+                crc = (crc >> 2) ^ tab[0][crc & 3];
+                crc = (crc >> 2) ^ tab[0][crc & 3];
+                crc = (crc >> 2) ^ tab[0][crc & 3];
         }
 # elif CRC_LE_BITS == 4
         while (len--) {
                 crc ^= *p++;
-                crc = (crc >> 4) ^ crc32table_le[0][crc & 15];
-                crc = (crc >> 4) ^ crc32table_le[0][crc & 15];
+                crc = (crc >> 4) ^ tab[0][crc & 15];
+                crc = (crc >> 4) ^ tab[0][crc & 15];
         }
 # elif CRC_LE_BITS == 8
         /* aka Sarwate algorithm */
         while (len--) {
                 crc ^= *p++;
-                crc = (crc >> 8) ^ crc32table_le[0][crc & 255];
+                crc = (crc >> 8) ^ tab[0][crc & 255];
         }
 # else
-        const u32      (*tab)[] = crc32table_le;
-
         crc = (__force u32) __cpu_to_le32(crc);
         crc = crc32_body(crc, p, len, tab);
         crc = __le32_to_cpu((__force __le32)crc);
 #endif
         return crc;
 }
+
+#if CRC_LE_BITS == 1
+u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+{
+        return crc32_le_generic(crc, p, len, NULL, CRCPOLY_LE);
+}
+u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
+{
+        return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);
+}
+#else
+u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
+{
+        return crc32_le_generic(crc, p, len, crc32table_le, CRCPOLY_LE);
+}
+u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
+{
+        return crc32_le_generic(crc, p, len, crc32ctable_le, CRC32C_POLY_LE);
+}
+#endif
 EXPORT_SYMBOL(crc32_le);
+EXPORT_SYMBOL(__crc32c_le);
 
 /**
  * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
@@ -182,7 +203,9 @@ EXPORT_SYMBOL(crc32_le);
  * @p: pointer to buffer over which CRC is run
  * @len: length of buffer @p
  */
-u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
+static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p,
+                                          size_t len, const u32 (*tab)[256],
+                                          u32 polynomial)
 {
 #if CRC_BE_BITS == 1
         int i;
@@ -190,37 +213,47 @@ u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
                 crc ^= *p++ << 24;
                 for (i = 0; i < 8; i++)
                         crc =
-                            (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE :
+                            (crc << 1) ^ ((crc & 0x80000000) ? polynomial :
                                           0);
         }
 # elif CRC_BE_BITS == 2
         while (len--) {
                 crc ^= *p++ << 24;
-                crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
-                crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
-                crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
-                crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
+                crc = (crc << 2) ^ tab[0][crc >> 30];
+                crc = (crc << 2) ^ tab[0][crc >> 30];
+                crc = (crc << 2) ^ tab[0][crc >> 30];
+                crc = (crc << 2) ^ tab[0][crc >> 30];
         }
 # elif CRC_BE_BITS == 4
         while (len--) {
                 crc ^= *p++ << 24;
-                crc = (crc << 4) ^ crc32table_be[0][crc >> 28];
-                crc = (crc << 4) ^ crc32table_be[0][crc >> 28];
+                crc = (crc << 4) ^ tab[0][crc >> 28];
+                crc = (crc << 4) ^ tab[0][crc >> 28];
         }
 # elif CRC_BE_BITS == 8
         while (len--) {
                 crc ^= *p++ << 24;
-                crc = (crc << 8) ^ crc32table_be[0][crc >> 24];
+                crc = (crc << 8) ^ tab[0][crc >> 24];
         }
 # else
-        const u32      (*tab)[] = crc32table_be;
-
         crc = (__force u32) __cpu_to_be32(crc);
         crc = crc32_body(crc, p, len, tab);
         crc = __be32_to_cpu((__force __be32)crc);
 # endif
         return crc;
 }
+
+#if CRC_LE_BITS == 1
+u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
+{
+        return crc32_be_generic(crc, p, len, NULL, CRCPOLY_BE);
+}
+#else
+u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
+{
+        return crc32_be_generic(crc, p, len, crc32table_be, CRCPOLY_BE);
+}
+#endif
 EXPORT_SYMBOL(crc32_be);
 
 #ifdef CONFIG_CRC32_SELFTEST
diff --git a/lib/crc32defs.h b/lib/crc32defs.h
index 818159288489..6fd191732fec 100644
--- a/lib/crc32defs.h
+++ b/lib/crc32defs.h
@@ -7,6 +7,13 @@
 #define CRCPOLY_BE 0x04c11db7
 
 /*
+ * This is the CRC32c polynomial, as outlined by Castagnoli.
+ * x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+x^11+x^10+x^9+
+ * x^8+x^6+x^0
+ */
+#define CRC32C_POLY_LE 0x82F63B78
+
+/*
  * How many bits at a time to use.  Valid values are 1, 2, 4, 8, 32 and 64.
  * For less performance-sensitive, use 4 or 8 to save table size.
  * For larger systems choose same as CPU architecture as default.
diff --git a/lib/gen_crc32table.c b/lib/gen_crc32table.c
index 0d9edd17ee13..8f8d5439e2d9 100644
--- a/lib/gen_crc32table.c
+++ b/lib/gen_crc32table.c
@@ -23,6 +23,7 @@
 
 static uint32_t crc32table_le[LE_TABLE_ROWS][256];
 static uint32_t crc32table_be[BE_TABLE_ROWS][256];
+static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];
 
 /**
  * crc32init_le() - allocate and initialize LE table data
@@ -31,27 +32,38 @@ static uint32_t crc32table_be[BE_TABLE_ROWS][256];
  * fact that crctable[i^j] = crctable[i] ^ crctable[j].
  *
  */
-static void crc32init_le(void)
+static void crc32init_le_generic(const uint32_t polynomial,
+                                 uint32_t (*tab)[256])
 {
         unsigned i, j;
         uint32_t crc = 1;
 
-        crc32table_le[0][0] = 0;
+        tab[0][0] = 0;
 
         for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
-                crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
+                crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
                 for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
-                        crc32table_le[0][i + j] = crc ^ crc32table_le[0][j];
+                        tab[0][i + j] = crc ^ tab[0][j];
         }
         for (i = 0; i < LE_TABLE_SIZE; i++) {
-                crc = crc32table_le[0][i];
+                crc = tab[0][i];
                 for (j = 1; j < LE_TABLE_ROWS; j++) {
-                        crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8);
-                        crc32table_le[j][i] = crc;
+                        crc = tab[0][crc & 0xff] ^ (crc >> 8);
+                        tab[j][i] = crc;
                 }
         }
 }
 
+static void crc32init_le(void)
+{
+        crc32init_le_generic(CRCPOLY_LE, crc32table_le);
+}
+
+static void crc32cinit_le(void)
+{
+        crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
+}
+
 /**
  * crc32init_be() - allocate and initialize BE table data
  */
@@ -114,6 +126,15 @@ int main(int argc, char** argv)
                              BE_TABLE_SIZE, "tobe");
                 printf("};\n");
         }
+        if (CRC_LE_BITS > 1) {
+                crc32cinit_le();
+                printf("static const u32 __cacheline_aligned "
+                       "crc32ctable_le[%d][%d] = {",
+                       LE_TABLE_ROWS, LE_TABLE_SIZE);
+                output_table(crc32ctable_le, LE_TABLE_ROWS,
+                             LE_TABLE_SIZE, "tole");
+                printf("};\n");
+        }
 
         return 0;
 }