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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>
This commit is contained in:
Chris Mason 2008-08-04 11:10:20 -04:00
parent 6dab815743
commit 3117a77370
1 changed files with 93 additions and 2 deletions
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95
fs/btrfs/crc32c.h
View File

@ -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