1/* GPL HEADER START
2 *
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 only,
7 * as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License version 2 for more details (a copy is included
13 * in the LICENSE file that accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License
16 * version 2 along with this program; If not, see http://www.gnu.org/licenses
17 *
18 * Please visit http://www.xyratex.com/contact if you need additional
19 * information or have any questions.
20 *
21 * GPL HEADER END
22 */
23
24/*
25 * Copyright 2012 Xyratex Technology Limited
26 *
27 * Wrappers for kernel crypto shash api to pclmulqdq crc32 implementation.
28 */
29#include <linux/init.h>
30#include <linux/module.h>
31#include <linux/string.h>
32#include <linux/kernel.h>
33#include <linux/crc32.h>
34#include <crypto/internal/hash.h>
35#include <crypto/internal/simd.h>
36
37#include <asm/cpufeatures.h>
38#include <asm/cpu_device_id.h>
39#include <asm/simd.h>
40
41#define CHKSUM_BLOCK_SIZE 1
42#define CHKSUM_DIGEST_SIZE 4
43
44#define PCLMUL_MIN_LEN 64L /* minimum size of buffer
45 * for crc32_pclmul_le_16 */
46#define SCALE_F 16L /* size of xmm register */
47#define SCALE_F_MASK (SCALE_F - 1)
48
49u32 crc32_pclmul_le_16(unsigned char const *buffer, size_t len, u32 crc32);
50
51static u32 __attribute__((pure))
52 crc32_pclmul_le(u32 crc, unsigned char const *p, size_t len)
53{
54 unsigned int iquotient;
55 unsigned int iremainder;
56 unsigned int prealign;
57
58 if (len < PCLMUL_MIN_LEN + SCALE_F_MASK || !crypto_simd_usable())
59 return crc32_le(crc, p, len);
60
61 if ((long)p & SCALE_F_MASK) {
62 /* align p to 16 byte */
63 prealign = SCALE_F - ((long)p & SCALE_F_MASK);
64
65 crc = crc32_le(crc, p, prealign);
66 len -= prealign;
67 p = (unsigned char *)(((unsigned long)p + SCALE_F_MASK) &
68 ~SCALE_F_MASK);
69 }
70 iquotient = len & (~SCALE_F_MASK);
71 iremainder = len & SCALE_F_MASK;
72
73 kernel_fpu_begin();
74 crc = crc32_pclmul_le_16(p, iquotient, crc);
75 kernel_fpu_end();
76
77 if (iremainder)
78 crc = crc32_le(crc, p + iquotient, iremainder);
79
80 return crc;
81}
82
83static int crc32_pclmul_cra_init(struct crypto_tfm *tfm)
84{
85 u32 *key = crypto_tfm_ctx(tfm);
86
87 *key = 0;
88
89 return 0;
90}
91
92static int crc32_pclmul_setkey(struct crypto_shash *hash, const u8 *key,
93 unsigned int keylen)
94{
95 u32 *mctx = crypto_shash_ctx(hash);
96
97 if (keylen != sizeof(u32))
98 return -EINVAL;
99 *mctx = le32_to_cpup((__le32 *)key);
100 return 0;
101}
102
103static int crc32_pclmul_init(struct shash_desc *desc)
104{
105 u32 *mctx = crypto_shash_ctx(desc->tfm);
106 u32 *crcp = shash_desc_ctx(desc);
107
108 *crcp = *mctx;
109
110 return 0;
111}
112
113static int crc32_pclmul_update(struct shash_desc *desc, const u8 *data,
114 unsigned int len)
115{
116 u32 *crcp = shash_desc_ctx(desc);
117
118 *crcp = crc32_pclmul_le(*crcp, data, len);
119 return 0;
120}
121
122/* No final XOR 0xFFFFFFFF, like crc32_le */
123static int __crc32_pclmul_finup(u32 *crcp, const u8 *data, unsigned int len,
124 u8 *out)
125{
126 *(__le32 *)out = cpu_to_le32(crc32_pclmul_le(*crcp, data, len));
127 return 0;
128}
129
130static int crc32_pclmul_finup(struct shash_desc *desc, const u8 *data,
131 unsigned int len, u8 *out)
132{
133 return __crc32_pclmul_finup(shash_desc_ctx(desc), data, len, out);
134}
135
136static int crc32_pclmul_final(struct shash_desc *desc, u8 *out)
137{
138 u32 *crcp = shash_desc_ctx(desc);
139
140 *(__le32 *)out = cpu_to_le32p(crcp);
141 return 0;
142}
143
144static int crc32_pclmul_digest(struct shash_desc *desc, const u8 *data,
145 unsigned int len, u8 *out)
146{
147 return __crc32_pclmul_finup(crypto_shash_ctx(desc->tfm), data, len,
148 out);
149}
150
151static struct shash_alg alg = {
152 .setkey = crc32_pclmul_setkey,
153 .init = crc32_pclmul_init,
154 .update = crc32_pclmul_update,
155 .final = crc32_pclmul_final,
156 .finup = crc32_pclmul_finup,
157 .digest = crc32_pclmul_digest,
158 .descsize = sizeof(u32),
159 .digestsize = CHKSUM_DIGEST_SIZE,
160 .base = {
161 .cra_name = "crc32",
162 .cra_driver_name = "crc32-pclmul",
163 .cra_priority = 200,
164 .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
165 .cra_blocksize = CHKSUM_BLOCK_SIZE,
166 .cra_ctxsize = sizeof(u32),
167 .cra_module = THIS_MODULE,
168 .cra_init = crc32_pclmul_cra_init,
169 }
170};
171
172static const struct x86_cpu_id crc32pclmul_cpu_id[] = {
173 X86_MATCH_FEATURE(X86_FEATURE_PCLMULQDQ, NULL),
174 {}
175};
176MODULE_DEVICE_TABLE(x86cpu, crc32pclmul_cpu_id);
177
178
179static int __init crc32_pclmul_mod_init(void)
180{
181
182 if (!x86_match_cpu(crc32pclmul_cpu_id)) {
183 pr_info("PCLMULQDQ-NI instructions are not detected.\n");
184 return -ENODEV;
185 }
186 return crypto_register_shash(&alg);
187}
188
189static void __exit crc32_pclmul_mod_fini(void)
190{
191 crypto_unregister_shash(&alg);
192}
193
194module_init(crc32_pclmul_mod_init);
195module_exit(crc32_pclmul_mod_fini);
196
197MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
198MODULE_LICENSE("GPL");
199
200MODULE_ALIAS_CRYPTO("crc32");
201MODULE_ALIAS_CRYPTO("crc32-pclmul");
202

source code of linux/arch/x86/crypto/crc32-pclmul_glue.c