[PATCH v2 02/12] lib/crc-t10dif: add support for arch overrides

[Eric Biggers]

From: Eric Biggers <ebiggers at google.com>

Following what was done for CRC32, add support for architecture-specific
override of the CRC-T10DIF library.  This will allow the CRC-T10DIF
library functions to access architecture-optimized code directly.

Reviewed-by: Ard Biesheuvel <ardb at kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen at oracle.com>
Signed-off-by: Eric Biggers <ebiggers at google.com>
---
 include/linux/crc-t10dif.h | 12 ++++++++++++
 lib/Kconfig                | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/include/linux/crc-t10dif.h b/include/linux/crc-t10dif.h
index 206ba2305483..16787c1cee21 100644
--- a/include/linux/crc-t10dif.h
+++ b/include/linux/crc-t10dif.h
@@ -5,18 +5,30 @@
 #include <linux/types.h>
 
 #define CRC_T10DIF_DIGEST_SIZE 2
 #define CRC_T10DIF_BLOCK_SIZE 1
 
+u16 crc_t10dif_arch(u16 crc, const u8 *p, size_t len);
 u16 crc_t10dif_generic(u16 crc, const u8 *p, size_t len);
 
 static inline u16 crc_t10dif_update(u16 crc, const u8 *p, size_t len)
 {
+	if (IS_ENABLED(CONFIG_CRC_T10DIF_ARCH))
+		return crc_t10dif_arch(crc, p, len);
 	return crc_t10dif_generic(crc, p, len);
 }
 
 static inline u16 crc_t10dif(const u8 *p, size_t len)
 {
 	return crc_t10dif_update(0, p, len);
 }
 
+#if IS_ENABLED(CONFIG_CRC_T10DIF_ARCH)
+bool crc_t10dif_is_optimized(void);
+#else
+static inline bool crc_t10dif_is_optimized(void)
+{
+	return false;
+}
+#endif
+
 #endif
diff --git a/lib/Kconfig b/lib/Kconfig
index be59f7cdf448..e52a38d8d783 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -159,10 +159,42 @@ config CRC_T10DIF
 	help
 	  This option is only needed if a module that's not in the
 	  kernel tree needs to calculate CRC checks for use with the
 	  SCSI data integrity subsystem.
 
+config ARCH_HAS_CRC_T10DIF
+	bool
+
+choice
+	prompt "CRC-T10DIF implementation"
+	depends on CRC_T10DIF
+	default CRC_T10DIF_IMPL_ARCH if ARCH_HAS_CRC_T10DIF
+	default CRC_T10DIF_IMPL_GENERIC if !ARCH_HAS_CRC_T10DIF
+	help
+	  This option allows you to override the default choice of CRC-T10DIF
+	  implementation.
+
+config CRC_T10DIF_IMPL_ARCH
+	bool "Architecture-optimized" if ARCH_HAS_CRC_T10DIF
+	help
+	  Use the optimized implementation of CRC-T10DIF for the selected
+	  architecture.  It is recommended to keep this enabled, as it can
+	  greatly improve CRC-T10DIF performance.
+
+config CRC_T10DIF_IMPL_GENERIC
+	bool "Generic implementation"
+	help
+	  Use the generic table-based implementation of CRC-T10DIF.  Selecting
+	  this will reduce code size slightly but can greatly reduce CRC-T10DIF
+	  performance.
+
+endchoice
+
+config CRC_T10DIF_ARCH
+	tristate
+	default CRC_T10DIF if CRC_T10DIF_IMPL_ARCH
+
 config CRC64_ROCKSOFT
 	tristate "CRC calculation for the Rocksoft model CRC64"
 	select CRC64
 	select CRYPTO
 	select CRYPTO_CRC64_ROCKSOFT
-- 
2.47.1