1 files changed, 120 insertions, 0 deletions
diff --git a/fs/btrfs/crc32c.h b/fs/btrfs/crc32c.h
new file mode 100644
index 00000000000..1eaf11d334f
--- /dev/null
+++ b/fs/btrfs/crc32c.h
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2008 Oracle.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#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.
+ * We must workaround older implementations of crc32c_le()
+ * found on older kernel versions.
+ */
+#define btrfs_crc32c(seed, data, length) \
+	__btrfs_crc32c(seed, (unsigned char const *)data, length)
+#endif
+