xref: /openbmc/linux/lib/crc-t10dif.c (revision 84d517f3)
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