1 /* 2 * T10 Data Integrity Field CRC16 calculation 3 * 4 * Copyright (c) 2007 Oracle Corporation. All rights reserved. 5 * Written by Martin K. Petersen <martin.petersen@oracle.com> 6 * 7 * This source code is licensed under the GNU General Public License, 8 * Version 2. See the file COPYING for more details. 9 */ 10 11 #include <linux/types.h> 12 #include <linux/module.h> 13 #include <linux/crc-t10dif.h> 14 #include <linux/err.h> 15 #include <linux/init.h> 16 #include <crypto/hash.h> 17 #include <linux/static_key.h> 18 19 static struct crypto_shash *crct10dif_tfm; 20 static struct static_key crct10dif_fallback __read_mostly; 21 22 __u16 crc_t10dif(const unsigned char *buffer, size_t len) 23 { 24 struct { 25 struct shash_desc shash; 26 char ctx[2]; 27 } desc; 28 int err; 29 30 if (static_key_false(&crct10dif_fallback)) 31 return crc_t10dif_generic(0, buffer, len); 32 33 desc.shash.tfm = crct10dif_tfm; 34 desc.shash.flags = 0; 35 *(__u16 *)desc.ctx = 0; 36 37 err = crypto_shash_update(&desc.shash, buffer, len); 38 BUG_ON(err); 39 40 return *(__u16 *)desc.ctx; 41 } 42 EXPORT_SYMBOL(crc_t10dif); 43 44 static int __init crc_t10dif_mod_init(void) 45 { 46 crct10dif_tfm = crypto_alloc_shash("crct10dif", 0, 0); 47 if (IS_ERR(crct10dif_tfm)) { 48 static_key_slow_inc(&crct10dif_fallback); 49 crct10dif_tfm = NULL; 50 } 51 return 0; 52 } 53 54 static void __exit crc_t10dif_mod_fini(void) 55 { 56 crypto_free_shash(crct10dif_tfm); 57 } 58 59 module_init(crc_t10dif_mod_init); 60 module_exit(crc_t10dif_mod_fini); 61 62 MODULE_DESCRIPTION("T10 DIF CRC calculation"); 63 MODULE_LICENSE("GPL"); 64 MODULE_SOFTDEP("pre: crct10dif"); 65