1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
4 * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
5 * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
6 * http://www.intel.com/products/processor/manuals/
7 * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
8 * Volume 2A: Instruction Set Reference, A-M
9 *
10 * Copyright (C) 2008 Intel Corporation
11 * Authors: Austin Zhang <austin_zhang@linux.intel.com>
12 * Kent Liu <kent.liu@intel.com>
13 */
14#include <linux/init.h>
15#include <linux/module.h>
16#include <linux/string.h>
17#include <linux/kernel.h>
18#include <crypto/internal/hash.h>
19#include <crypto/internal/simd.h>
20
21#include <asm/cpufeatures.h>
22#include <asm/cpu_device_id.h>
23#include <asm/simd.h>
24
25#define CHKSUM_BLOCK_SIZE 1
26#define CHKSUM_DIGEST_SIZE 4
27
28#define SCALE_F sizeof(unsigned long)
29
30#ifdef CONFIG_X86_64
31#define CRC32_INST "crc32q %1, %q0"
32#else
33#define CRC32_INST "crc32l %1, %0"
34#endif
35
36#ifdef CONFIG_X86_64
37/*
38 * use carryless multiply version of crc32c when buffer
39 * size is >= 512 to account
40 * for fpu state save/restore overhead.
41 */
42#define CRC32C_PCL_BREAKEVEN 512
43
44asmlinkage unsigned int crc_pcl(const u8 *buffer, int len,
45 unsigned int crc_init);
46#endif /* CONFIG_X86_64 */
47
48static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
49{
50 while (length--) {
51 asm("crc32b %1, %0"
52 : "+r" (crc) : "rm" (*data));
53 data++;
54 }
55
56 return crc;
57}
58
59static u32 __pure crc32c_intel_le_hw(u32 crc, unsigned char const *p, size_t len)
60{
61 unsigned int iquotient = len / SCALE_F;
62 unsigned int iremainder = len % SCALE_F;
63 unsigned long *ptmp = (unsigned long *)p;
64
65 while (iquotient--) {
66 asm(CRC32_INST
67 : "+r" (crc) : "rm" (*ptmp));
68 ptmp++;
69 }
70
71 if (iremainder)
72 crc = crc32c_intel_le_hw_byte(crc, data: (unsigned char *)ptmp,
73 length: iremainder);
74
75 return crc;
76}
77
78/*
79 * Setting the seed allows arbitrary accumulators and flexible XOR policy
80 * If your algorithm starts with ~0, then XOR with ~0 before you set
81 * the seed.
82 */
83static int crc32c_intel_setkey(struct crypto_shash *hash, const u8 *key,
84 unsigned int keylen)
85{
86 u32 *mctx = crypto_shash_ctx(tfm: hash);
87
88 if (keylen != sizeof(u32))
89 return -EINVAL;
90 *mctx = le32_to_cpup(p: (__le32 *)key);
91 return 0;
92}
93
94static int crc32c_intel_init(struct shash_desc *desc)
95{
96 u32 *mctx = crypto_shash_ctx(tfm: desc->tfm);
97 u32 *crcp = shash_desc_ctx(desc);
98
99 *crcp = *mctx;
100
101 return 0;
102}
103
104static int crc32c_intel_update(struct shash_desc *desc, const u8 *data,
105 unsigned int len)
106{
107 u32 *crcp = shash_desc_ctx(desc);
108
109 *crcp = crc32c_intel_le_hw(crc: *crcp, p: data, len);
110 return 0;
111}
112
113static int __crc32c_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
114 u8 *out)
115{
116 *(__le32 *)out = ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
117 return 0;
118}
119
120static int crc32c_intel_finup(struct shash_desc *desc, const u8 *data,
121 unsigned int len, u8 *out)
122{
123 return __crc32c_intel_finup(crcp: shash_desc_ctx(desc), data, len, out);
124}
125
126static int crc32c_intel_final(struct shash_desc *desc, u8 *out)
127{
128 u32 *crcp = shash_desc_ctx(desc);
129
130 *(__le32 *)out = ~cpu_to_le32p(p: crcp);
131 return 0;
132}
133
134static int crc32c_intel_digest(struct shash_desc *desc, const u8 *data,
135 unsigned int len, u8 *out)
136{
137 return __crc32c_intel_finup(crcp: crypto_shash_ctx(tfm: desc->tfm), data, len,
138 out);
139}
140
141static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
142{
143 u32 *key = crypto_tfm_ctx(tfm);
144
145 *key = ~0;
146
147 return 0;
148}
149
150#ifdef CONFIG_X86_64
151static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
152 unsigned int len)
153{
154 u32 *crcp = shash_desc_ctx(desc);
155
156 /*
157 * use faster PCL version if datasize is large enough to
158 * overcome kernel fpu state save/restore overhead
159 */
160 if (len >= CRC32C_PCL_BREAKEVEN && crypto_simd_usable()) {
161 kernel_fpu_begin();
162 *crcp = crc_pcl(buffer: data, len, crc_init: *crcp);
163 kernel_fpu_end();
164 } else
165 *crcp = crc32c_intel_le_hw(crc: *crcp, p: data, len);
166 return 0;
167}
168
169static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
170 u8 *out)
171{
172 if (len >= CRC32C_PCL_BREAKEVEN && crypto_simd_usable()) {
173 kernel_fpu_begin();
174 *(__le32 *)out = ~cpu_to_le32(crc_pcl(data, len, *crcp));
175 kernel_fpu_end();
176 } else
177 *(__le32 *)out =
178 ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
179 return 0;
180}
181
182static int crc32c_pcl_intel_finup(struct shash_desc *desc, const u8 *data,
183 unsigned int len, u8 *out)
184{
185 return __crc32c_pcl_intel_finup(crcp: shash_desc_ctx(desc), data, len, out);
186}
187
188static int crc32c_pcl_intel_digest(struct shash_desc *desc, const u8 *data,
189 unsigned int len, u8 *out)
190{
191 return __crc32c_pcl_intel_finup(crcp: crypto_shash_ctx(tfm: desc->tfm), data, len,
192 out);
193}
194#endif /* CONFIG_X86_64 */
195
196static struct shash_alg alg = {
197 .setkey = crc32c_intel_setkey,
198 .init = crc32c_intel_init,
199 .update = crc32c_intel_update,
200 .final = crc32c_intel_final,
201 .finup = crc32c_intel_finup,
202 .digest = crc32c_intel_digest,
203 .descsize = sizeof(u32),
204 .digestsize = CHKSUM_DIGEST_SIZE,
205 .base = {
206 .cra_name = "crc32c",
207 .cra_driver_name = "crc32c-intel",
208 .cra_priority = 200,
209 .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
210 .cra_blocksize = CHKSUM_BLOCK_SIZE,
211 .cra_ctxsize = sizeof(u32),
212 .cra_module = THIS_MODULE,
213 .cra_init = crc32c_intel_cra_init,
214 }
215};
216
217static const struct x86_cpu_id crc32c_cpu_id[] = {
218 X86_MATCH_FEATURE(X86_FEATURE_XMM4_2, NULL),
219 {}
220};
221MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
222
223static int __init crc32c_intel_mod_init(void)
224{
225 if (!x86_match_cpu(match: crc32c_cpu_id))
226 return -ENODEV;
227#ifdef CONFIG_X86_64
228 if (boot_cpu_has(X86_FEATURE_PCLMULQDQ)) {
229 alg.update = crc32c_pcl_intel_update;
230 alg.finup = crc32c_pcl_intel_finup;
231 alg.digest = crc32c_pcl_intel_digest;
232 }
233#endif
234 return crypto_register_shash(alg: &alg);
235}
236
237static void __exit crc32c_intel_mod_fini(void)
238{
239 crypto_unregister_shash(alg: &alg);
240}
241
242module_init(crc32c_intel_mod_init);
243module_exit(crc32c_intel_mod_fini);
244
245MODULE_AUTHOR("Austin Zhang <austin.zhang@intel.com>, Kent Liu <kent.liu@intel.com>");
246MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
247MODULE_LICENSE("GPL");
248
249MODULE_ALIAS_CRYPTO("crc32c");
250MODULE_ALIAS_CRYPTO("crc32c-intel");
251

source code of linux/arch/x86/crypto/crc32c-intel_glue.c