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lib/crc32: make crc32c() go directly to lib

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Now that the lower level __crc32c_le() library function is optimized for
each architecture, make crc32c() just call that instead of taking an
inefficient and error-prone detour through the shash API.

Note: a future cleanup should make crc32c_le() be the actual library
function instead of __crc32c_le().  That will require updating callers
of __crc32c_le() to use crc32c_le() instead, and updating callers of
crc32c_le() that expect a 'const void *' arg to expect 'const u8 *'
instead.  Similarly, a future cleanup should remove LIBCRC32C by making
everyone who is selecting it just select CRC32 directly instead.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20241202010844.144356-16-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
This commit is contained in:
Eric Biggers 2024-12-01 17:08:40 -08:00
parent cc354fa7f0
commit 38a9a5121c
4 changed files with 8 additions and 84 deletions
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7
include/linux/crc32c.h
View File

@ -2,9 +2,12 @@
#ifndef _LINUX_CRC32C_H
#define _LINUX_CRC32C_H
#include <linux/types.h>
#include <linux/crc32.h>
extern u32 crc32c(u32 crc, const void *address, unsigned int length);
static inline u32 crc32c(u32 crc, const void *address, unsigned int length)
{
return __crc32c_le(crc, address, length);
}
/* This macro exists for backwards-compatibility. */
#define crc32c_le crc32c

10
lib/Kconfig
View File

@ -310,14 +310,10 @@ config CRC7
config LIBCRC32C
tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
select CRYPTO
select CRYPTO_CRC32C
select CRC32
help
This option is provided for the case where no in-kernel-tree
modules require CRC32c functions, but a module built outside the
kernel tree does. Such modules that use library CRC32c functions
require M here. See Castagnoli93.
Module will be libcrc32c.
This option just selects CRC32 and is provided for compatibility
purposes until the users are updated to select CRC32 directly.
config CRC8
tristate "CRC8 function"

1
lib/Makefile
View File

@ -167,7 +167,6 @@ obj-$(CONFIG_CRC64) += crc64.o
obj-$(CONFIG_CRC32_SELFTEST) += crc32test.o
obj-$(CONFIG_CRC4) += crc4.o
obj-$(CONFIG_CRC7) += crc7.o
obj-$(CONFIG_LIBCRC32C) += libcrc32c.o
obj-$(CONFIG_CRC8) += crc8.o
obj-$(CONFIG_CRC64_ROCKSOFT) += crc64-rocksoft.o
obj-$(CONFIG_XXHASH) += xxhash.o

74
lib/libcrc32c.c
View File

@ -1,74 +0,0 @@
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* CRC32C
*@Article{castagnoli-crc,
* author = { Guy Castagnoli and Stefan Braeuer and Martin Herrman},
* title = {{Optimization of Cyclic Redundancy-Check Codes with 24
* and 32 Parity Bits}},
* journal = IEEE Transactions on Communication,
* year = {1993},
* volume = {41},
* number = {6},
* pages = {},
* month = {June},
*}
* Used by the iSCSI driver, possibly others, and derived from
* the iscsi-crc.c module of the linux-iscsi driver at
* http://linux-iscsi.sourceforge.net.
*
* Following the example of lib/crc32, this function is intended to be
* flexible and useful for all users. Modules that currently have their
* own crc32c, but hopefully may be able to use this one are:
* net/sctp (please add all your doco to here if you change to
* use this one!)
* <endoflist>
*
* Copyright (c) 2004 Cisco Systems, Inc.
*/
#include <crypto/hash.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/crc32c.h>
static struct crypto_shash *tfm;
u32 crc32c(u32 crc, const void *address, unsigned int length)
{
SHASH_DESC_ON_STACK(shash, tfm);
u32 ret, *ctx = (u32 *)shash_desc_ctx(shash);
int err;
shash->tfm = tfm;
*ctx = crc;
err = crypto_shash_update(shash, address, length);
BUG_ON(err);
ret = *ctx;
barrier_data(ctx);
return ret;
}
EXPORT_SYMBOL(crc32c);
static int __init libcrc32c_mod_init(void)
{
tfm = crypto_alloc_shash("crc32c", 0, 0);
return PTR_ERR_OR_ZERO(tfm);
}
static void __exit libcrc32c_mod_fini(void)
{
crypto_free_shash(tfm);
}
module_init(libcrc32c_mod_init);
module_exit(libcrc32c_mod_fini);
MODULE_AUTHOR("Clay Haapala <chaapala@cisco.com>");
MODULE_DESCRIPTION("CRC32c (Castagnoli) calculations");
MODULE_LICENSE("GPL");
MODULE_SOFTDEP("pre: crc32c");