1/*
2 * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
3 * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
4 * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
5 * http://www.intel.com/products/processor/manuals/
6 * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
7 * Volume 2A: Instruction Set Reference, A-M
8 *
9 * Copyright (C) 2008 Intel Corporation
10 * Authors: Austin Zhang <austin_zhang@linux.intel.com>
11 * Kent Liu <kent.liu@intel.com>
12 *
13 * This program is free software; you can redistribute it and/or modify it
14 * under the terms and conditions of the GNU General Public License,
15 * version 2, as published by the Free Software Foundation.
16 *
17 * This program is distributed in the hope it will be useful, but WITHOUT
18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
20 * more details.
21 *
22 * You should have received a copy of the GNU General Public License along with
23 * this program; if not, write to the Free Software Foundation, Inc.,
24 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
25 *
26 */
27#include <linux/init.h>
28#include <linux/module.h>
29#include <linux/string.h>
30#include <linux/kernel.h>
31#include <crypto/internal/hash.h>
32
33#include <asm/cpufeatures.h>
34#include <asm/cpu_device_id.h>
35#include <asm/fpu/internal.h>
36
37#define CHKSUM_BLOCK_SIZE 1
38#define CHKSUM_DIGEST_SIZE 4
39
40#define SCALE_F sizeof(unsigned long)
41
42#ifdef CONFIG_X86_64
43#define REX_PRE "0x48, "
44#else
45#define REX_PRE
46#endif
47
48#ifdef CONFIG_X86_64
49/*
50 * use carryless multiply version of crc32c when buffer
51 * size is >= 512 to account
52 * for fpu state save/restore overhead.
53 */
54#define CRC32C_PCL_BREAKEVEN 512
55
56asmlinkage unsigned int crc_pcl(const u8 *buffer, int len,
57 unsigned int crc_init);
58#endif /* CONFIG_X86_64 */
59
60static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
61{
62 while (length--) {
63 __asm__ __volatile__(
64 ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
65 :"=S"(crc)
66 :"0"(crc), "c"(*data)
67 );
68 data++;
69 }
70
71 return crc;
72}
73
74static u32 __pure crc32c_intel_le_hw(u32 crc, unsigned char const *p, size_t len)
75{
76 unsigned int iquotient = len / SCALE_F;
77 unsigned int iremainder = len % SCALE_F;
78 unsigned long *ptmp = (unsigned long *)p;
79
80 while (iquotient--) {
81 __asm__ __volatile__(
82 ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
83 :"=S"(crc)
84 :"0"(crc), "c"(*ptmp)
85 );
86 ptmp++;
87 }
88
89 if (iremainder)
90 crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
91 iremainder);
92
93 return crc;
94}
95
96/*
97 * Setting the seed allows arbitrary accumulators and flexible XOR policy
98 * If your algorithm starts with ~0, then XOR with ~0 before you set
99 * the seed.
100 */
101static int crc32c_intel_setkey(struct crypto_shash *hash, const u8 *key,
102 unsigned int keylen)
103{
104 u32 *mctx = crypto_shash_ctx(hash);
105
106 if (keylen != sizeof(u32)) {
107 crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
108 return -EINVAL;
109 }
110 *mctx = le32_to_cpup((__le32 *)key);
111 return 0;
112}
113
114static int crc32c_intel_init(struct shash_desc *desc)
115{
116 u32 *mctx = crypto_shash_ctx(desc->tfm);
117 u32 *crcp = shash_desc_ctx(desc);
118
119 *crcp = *mctx;
120
121 return 0;
122}
123
124static int crc32c_intel_update(struct shash_desc *desc, const u8 *data,
125 unsigned int len)
126{
127 u32 *crcp = shash_desc_ctx(desc);
128
129 *crcp = crc32c_intel_le_hw(*crcp, data, len);
130 return 0;
131}
132
133static int __crc32c_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
134 u8 *out)
135{
136 *(__le32 *)out = ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
137 return 0;
138}
139
140static int crc32c_intel_finup(struct shash_desc *desc, const u8 *data,
141 unsigned int len, u8 *out)
142{
143 return __crc32c_intel_finup(shash_desc_ctx(desc), data, len, out);
144}
145
146static int crc32c_intel_final(struct shash_desc *desc, u8 *out)
147{
148 u32 *crcp = shash_desc_ctx(desc);
149
150 *(__le32 *)out = ~cpu_to_le32p(crcp);
151 return 0;
152}
153
154static int crc32c_intel_digest(struct shash_desc *desc, const u8 *data,
155 unsigned int len, u8 *out)
156{
157 return __crc32c_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
158 out);
159}
160
161static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
162{
163 u32 *key = crypto_tfm_ctx(tfm);
164
165 *key = ~0;
166
167 return 0;
168}
169
170#ifdef CONFIG_X86_64
171static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
172 unsigned int len)
173{
174 u32 *crcp = shash_desc_ctx(desc);
175
176 /*
177 * use faster PCL version if datasize is large enough to
178 * overcome kernel fpu state save/restore overhead
179 */
180 if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) {
181 kernel_fpu_begin();
182 *crcp = crc_pcl(data, len, *crcp);
183 kernel_fpu_end();
184 } else
185 *crcp = crc32c_intel_le_hw(*crcp, data, len);
186 return 0;
187}
188
189static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
190 u8 *out)
191{
192 if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) {
193 kernel_fpu_begin();
194 *(__le32 *)out = ~cpu_to_le32(crc_pcl(data, len, *crcp));
195 kernel_fpu_end();
196 } else
197 *(__le32 *)out =
198 ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
199 return 0;
200}
201
202static int crc32c_pcl_intel_finup(struct shash_desc *desc, const u8 *data,
203 unsigned int len, u8 *out)
204{
205 return __crc32c_pcl_intel_finup(shash_desc_ctx(desc), data, len, out);
206}
207
208static int crc32c_pcl_intel_digest(struct shash_desc *desc, const u8 *data,
209 unsigned int len, u8 *out)
210{
211 return __crc32c_pcl_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
212 out);
213}
214#endif /* CONFIG_X86_64 */
215
216static struct shash_alg alg = {
217 .setkey = crc32c_intel_setkey,
218 .init = crc32c_intel_init,
219 .update = crc32c_intel_update,
220 .final = crc32c_intel_final,
221 .finup = crc32c_intel_finup,
222 .digest = crc32c_intel_digest,
223 .descsize = sizeof(u32),
224 .digestsize = CHKSUM_DIGEST_SIZE,
225 .base = {
226 .cra_name = "crc32c",
227 .cra_driver_name = "crc32c-intel",
228 .cra_priority = 200,
229 .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
230 .cra_blocksize = CHKSUM_BLOCK_SIZE,
231 .cra_ctxsize = sizeof(u32),
232 .cra_module = THIS_MODULE,
233 .cra_init = crc32c_intel_cra_init,
234 }
235};
236
237static const struct x86_cpu_id crc32c_cpu_id[] = {
238 X86_FEATURE_MATCH(X86_FEATURE_XMM4_2),
239 {}
240};
241MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
242
243static int __init crc32c_intel_mod_init(void)
244{
245 if (!x86_match_cpu(crc32c_cpu_id))
246 return -ENODEV;
247#ifdef CONFIG_X86_64
248 if (boot_cpu_has(X86_FEATURE_PCLMULQDQ)) {
249 alg.update = crc32c_pcl_intel_update;
250 alg.finup = crc32c_pcl_intel_finup;
251 alg.digest = crc32c_pcl_intel_digest;
252 }
253#endif
254 return crypto_register_shash(&alg);
255}
256
257static void __exit crc32c_intel_mod_fini(void)
258{
259 crypto_unregister_shash(&alg);
260}
261
262module_init(crc32c_intel_mod_init);
263module_exit(crc32c_intel_mod_fini);
264
265MODULE_AUTHOR("Austin Zhang <austin.zhang@intel.com>, Kent Liu <kent.liu@intel.com>");
266MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
267MODULE_LICENSE("GPL");
268
269MODULE_ALIAS_CRYPTO("crc32c");
270MODULE_ALIAS_CRYPTO("crc32c-intel");
271