Btrfs: Add support for HW assisted crc32c
Intel doesn't yet ship hardware to the public with this enabled, but when they
do, they will be ready. Original code from:
Austin Zhang <austin_zhang@linux.intel.com>
It is currently disabled, but edit crc32c.h to turn it on.
Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/crc32c.h b/fs/btrfs/crc32c.h
index a93255b..bf6c12e 100644
--- a/fs/btrfs/crc32c.h
+++ b/fs/btrfs/crc32c.h
@@ -1,7 +1,95 @@
+#ifndef __BTRFS_CRC32C__
+#define __BTRFS_CRC32C__
#include <asm/byteorder.h>
#include <linux/crc32c.h>
#include <linux/version.h>
+/* #define CONFIG_BTRFS_HW_SUM 1 */
+
+#ifdef CONFIG_BTRFS_HW_SUM
+#ifdef CONFIG_X86
+/*
+ * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
+ * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
+ * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
+ * http://www.intel.com/products/processor/manuals/
+ * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
+ * Volume 2A: Instruction Set Reference, A-M
+ */
+
+#include <asm/cpufeature.h>
+#include <asm/processor.h>
+
+#define X86_FEATURE_XMM4_2 (4*32+20) /* Streaming SIMD Extensions-4.2 */
+#define cpu_has_xmm4_2 boot_cpu_has(X86_FEATURE_XMM4_2)
+
+#ifdef CONFIG_X86_64
+#define REX_PRE "0x48, "
+#define SCALE_F 8
+#else
+#define REX_PRE
+#define SCALE_F 4
+#endif
+
+static inline u32 btrfs_crc32c_le_hw_byte(u32 crc, unsigned char const *data,
+ size_t length)
+{
+ while (length--) {
+ __asm__ __volatile__(
+ ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
+ :"=S"(crc)
+ :"0"(crc), "c"(*data)
+ );
+ data++;
+ }
+
+ return crc;
+}
+
+static inline u32 __pure btrfs_crc32c_le_hw(u32 crc, unsigned char const *p,
+ size_t len)
+{
+ unsigned int iquotient = len / SCALE_F;
+ unsigned int iremainder = len % SCALE_F;
+#ifdef CONFIG_X86_64
+ u64 *ptmp = (u64 *)p;
+#else
+ u32 *ptmp = (u32 *)p;
+#endif
+
+ while (iquotient--) {
+ __asm__ __volatile__(
+ ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
+ :"=S"(crc)
+ :"0"(crc), "c"(*ptmp)
+ );
+ ptmp++;
+ }
+
+ if (iremainder)
+ crc = btrfs_crc32c_le_hw_byte(crc, (unsigned char *)ptmp,
+ iremainder);
+
+ return crc;
+}
+#endif /* CONFIG_BTRFS_HW_SUM */
+
+static inline u32 __btrfs_crc32c(u32 crc, unsigned char const *address,
+ size_t len)
+{
+#ifdef CONFIG_BTRFS_HW_SUM
+ if (cpu_has_xmm4_2)
+ return btrfs_crc32c_le_hw(crc, address, len);
+#endif
+ return crc32c_le(crc, address, len);
+}
+
+#else
+
+#define __btrfs_crc32c(seed, data, length) crc32c(seed, data, length)
+
+#endif /* CONFIG_X86 */
+
/**
* implementation of crc32c_le() changed in linux-2.6.23,
* has of v0.13 btrfs-progs is using the latest version.
@@ -10,8 +98,11 @@
*/
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
#define btrfs_crc32c(seed, data, length) \
- __cpu_to_le32( crc32c( __le32_to_cpu(seed), data, length) )
+ __cpu_to_le32( __btrfs_crc32c( __le32_to_cpu(seed), \
+ (unsigned char const *)data, length) )
#else
#define btrfs_crc32c(seed, data, length) \
- crc32c(seed, data, length)
+ __btrfs_crc32c(seed, (unsigned char const *)data, length)
#endif
+#endif
+