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 imlementation.
 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
 36#include <asm/cpufeatures.h>
 37#include <asm/cpu_device_id.h>
 38#include <asm/fpu/api.h>
 39
 40#define CHKSUM_BLOCK_SIZE	1
 41#define CHKSUM_DIGEST_SIZE	4
 42
 43#define PCLMUL_MIN_LEN		64L     /* minimum size of buffer
 44					 * for crc32_pclmul_le_16 */
 45#define SCALE_F			16L	/* size of xmm register */
 46#define SCALE_F_MASK		(SCALE_F - 1)
 47
 48u32 crc32_pclmul_le_16(unsigned char const *buffer, size_t len, u32 crc32);
 49
 50static u32 __attribute__((pure))
 51	crc32_pclmul_le(u32 crc, unsigned char const *p, size_t len)
 52{
 53	unsigned int iquotient;
 54	unsigned int iremainder;
 55	unsigned int prealign;
 56
 57	if (len < PCLMUL_MIN_LEN + SCALE_F_MASK || !irq_fpu_usable())
 58		return crc32_le(crc, p, len);
 59
 60	if ((long)p & SCALE_F_MASK) {
 61		/* align p to 16 byte */
 62		prealign = SCALE_F - ((long)p & SCALE_F_MASK);
 63
 64		crc = crc32_le(crc, p, prealign);
 65		len -= prealign;
 66		p = (unsigned char *)(((unsigned long)p + SCALE_F_MASK) &
 67				     ~SCALE_F_MASK);
 68	}
 69	iquotient = len & (~SCALE_F_MASK);
 70	iremainder = len & SCALE_F_MASK;
 71
 72	kernel_fpu_begin();
 73	crc = crc32_pclmul_le_16(p, iquotient, crc);
 74	kernel_fpu_end();
 75
 76	if (iremainder)
 77		crc = crc32_le(crc, p + iquotient, iremainder);
 78
 79	return crc;
 80}
 81
 82static int crc32_pclmul_cra_init(struct crypto_tfm *tfm)
 83{
 84	u32 *key = crypto_tfm_ctx(tfm);
 85
 86	*key = 0;
 87
 88	return 0;
 89}
 90
 91static int crc32_pclmul_setkey(struct crypto_shash *hash, const u8 *key,
 92			unsigned int keylen)
 93{
 94	u32 *mctx = crypto_shash_ctx(hash);
 95
 96	if (keylen != sizeof(u32)) {
 97		crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
 98		return -EINVAL;
 99	}
100	*mctx = le32_to_cpup((__le32 *)key);
101	return 0;
102}
103
104static int crc32_pclmul_init(struct shash_desc *desc)
105{
106	u32 *mctx = crypto_shash_ctx(desc->tfm);
107	u32 *crcp = shash_desc_ctx(desc);
108
109	*crcp = *mctx;
110
111	return 0;
112}
113
114static int crc32_pclmul_update(struct shash_desc *desc, const u8 *data,
115			       unsigned int len)
116{
117	u32 *crcp = shash_desc_ctx(desc);
118
119	*crcp = crc32_pclmul_le(*crcp, data, len);
120	return 0;
121}
122
123/* No final XOR 0xFFFFFFFF, like crc32_le */
124static int __crc32_pclmul_finup(u32 *crcp, const u8 *data, unsigned int len,
125				u8 *out)
126{
127	*(__le32 *)out = cpu_to_le32(crc32_pclmul_le(*crcp, data, len));
128	return 0;
129}
130
131static int crc32_pclmul_finup(struct shash_desc *desc, const u8 *data,
132			      unsigned int len, u8 *out)
133{
134	return __crc32_pclmul_finup(shash_desc_ctx(desc), data, len, out);
135}
136
137static int crc32_pclmul_final(struct shash_desc *desc, u8 *out)
138{
139	u32 *crcp = shash_desc_ctx(desc);
140
141	*(__le32 *)out = cpu_to_le32p(crcp);
142	return 0;
143}
144
145static int crc32_pclmul_digest(struct shash_desc *desc, const u8 *data,
146			       unsigned int len, u8 *out)
147{
148	return __crc32_pclmul_finup(crypto_shash_ctx(desc->tfm), data, len,
149				    out);
150}
151
152static struct shash_alg alg = {
153	.setkey		= crc32_pclmul_setkey,
154	.init		= crc32_pclmul_init,
155	.update		= crc32_pclmul_update,
156	.final		= crc32_pclmul_final,
157	.finup		= crc32_pclmul_finup,
158	.digest		= crc32_pclmul_digest,
159	.descsize	= sizeof(u32),
160	.digestsize	= CHKSUM_DIGEST_SIZE,
161	.base		= {
162			.cra_name		= "crc32",
163			.cra_driver_name	= "crc32-pclmul",
164			.cra_priority		= 200,
165			.cra_flags		= CRYPTO_ALG_OPTIONAL_KEY,
166			.cra_blocksize		= CHKSUM_BLOCK_SIZE,
167			.cra_ctxsize		= sizeof(u32),
168			.cra_module		= THIS_MODULE,
169			.cra_init		= crc32_pclmul_cra_init,
170	}
171};
172
173static const struct x86_cpu_id crc32pclmul_cpu_id[] = {
174	X86_FEATURE_MATCH(X86_FEATURE_PCLMULQDQ),
175	{}
176};
177MODULE_DEVICE_TABLE(x86cpu, crc32pclmul_cpu_id);
178
179
180static int __init crc32_pclmul_mod_init(void)
181{
182
183	if (!x86_match_cpu(crc32pclmul_cpu_id)) {
184		pr_info("PCLMULQDQ-NI instructions are not detected.\n");
185		return -ENODEV;
186	}
187	return crypto_register_shash(&alg);
188}
189
190static void __exit crc32_pclmul_mod_fini(void)
191{
192	crypto_unregister_shash(&alg);
193}
194
195module_init(crc32_pclmul_mod_init);
196module_exit(crc32_pclmul_mod_fini);
197
198MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
199MODULE_LICENSE("GPL");
200
201MODULE_ALIAS_CRYPTO("crc32");
202MODULE_ALIAS_CRYPTO("crc32-pclmul");