1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Calculate a CRC T10-DIF with vpmsum acceleration
4 *
5 * Copyright 2017, Daniel Axtens, IBM Corporation.
6 * [based on crc32c-vpmsum_glue.c]
7 */
8
9#include <linux/crc-t10dif.h>
10#include <crypto/internal/hash.h>
11#include <crypto/internal/simd.h>
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/string.h>
15#include <linux/kernel.h>
16#include <linux/cpufeature.h>
17#include <asm/simd.h>
18#include <asm/switch_to.h>
19
20#define VMX_ALIGN		16
21#define VMX_ALIGN_MASK		(VMX_ALIGN-1)
22
23#define VECTOR_BREAKPOINT	64
24
25u32 __crct10dif_vpmsum(u32 crc, unsigned char const *p, size_t len);
26
27static u16 crct10dif_vpmsum(u16 crci, unsigned char const *p, size_t len)
28{
29	unsigned int prealign;
30	unsigned int tail;
31	u32 crc = crci;
32
33	if (len < (VECTOR_BREAKPOINT + VMX_ALIGN) || !crypto_simd_usable())
34		return crc_t10dif_generic(crc, p, len);
35
36	if ((unsigned long)p & VMX_ALIGN_MASK) {
37		prealign = VMX_ALIGN - ((unsigned long)p & VMX_ALIGN_MASK);
38		crc = crc_t10dif_generic(crc, p, prealign);
39		len -= prealign;
40		p += prealign;
41	}
42
43	if (len & ~VMX_ALIGN_MASK) {
44		crc <<= 16;
45		preempt_disable();
46		pagefault_disable();
47		enable_kernel_altivec();
48		crc = __crct10dif_vpmsum(crc, p, len & ~VMX_ALIGN_MASK);
49		disable_kernel_altivec();
50		pagefault_enable();
51		preempt_enable();
52		crc >>= 16;
53	}
54
55	tail = len & VMX_ALIGN_MASK;
56	if (tail) {
57		p += len & ~VMX_ALIGN_MASK;
58		crc = crc_t10dif_generic(crc, p, tail);
59	}
60
61	return crc & 0xffff;
62}
63
64static int crct10dif_vpmsum_init(struct shash_desc *desc)
65{
66	u16 *crc = shash_desc_ctx(desc);
67
68	*crc = 0;
69	return 0;
70}
71
72static int crct10dif_vpmsum_update(struct shash_desc *desc, const u8 *data,
73			    unsigned int length)
74{
75	u16 *crc = shash_desc_ctx(desc);
76
77	*crc = crct10dif_vpmsum(*crc, data, length);
78
79	return 0;
80}
81
82
83static int crct10dif_vpmsum_final(struct shash_desc *desc, u8 *out)
84{
85	u16 *crcp = shash_desc_ctx(desc);
86
87	*(u16 *)out = *crcp;
88	return 0;
89}
90
91static struct shash_alg alg = {
92	.init		= crct10dif_vpmsum_init,
93	.update		= crct10dif_vpmsum_update,
94	.final		= crct10dif_vpmsum_final,
95	.descsize	= CRC_T10DIF_DIGEST_SIZE,
96	.digestsize	= CRC_T10DIF_DIGEST_SIZE,
97	.base		= {
98		.cra_name		= "crct10dif",
99		.cra_driver_name	= "crct10dif-vpmsum",
100		.cra_priority		= 200,
101		.cra_blocksize		= CRC_T10DIF_BLOCK_SIZE,
102		.cra_module		= THIS_MODULE,
103	}
104};
105
106static int __init crct10dif_vpmsum_mod_init(void)
107{
108	if (!cpu_has_feature(CPU_FTR_ARCH_207S))
109		return -ENODEV;
110
111	return crypto_register_shash(&alg);
112}
113
114static void __exit crct10dif_vpmsum_mod_fini(void)
115{
116	crypto_unregister_shash(&alg);
117}
118
119module_cpu_feature_match(PPC_MODULE_FEATURE_VEC_CRYPTO, crct10dif_vpmsum_mod_init);
120module_exit(crct10dif_vpmsum_mod_fini);
121
122MODULE_AUTHOR("Daniel Axtens <dja@axtens.net>");
123MODULE_DESCRIPTION("CRCT10DIF using vector polynomial multiply-sum instructions");
124MODULE_LICENSE("GPL");
125MODULE_ALIAS_CRYPTO("crct10dif");
126MODULE_ALIAS_CRYPTO("crct10dif-vpmsum");
127