1/*
  2 * ChaCha20 256-bit cipher algorithm, RFC7539, SIMD glue code
  3 *
  4 * Copyright (C) 2015 Martin Willi
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; either version 2 of the License, or
  9 * (at your option) any later version.
 10 */
 11
 12#include <crypto/algapi.h>
 13#include <crypto/chacha20.h>
 14#include <linux/crypto.h>
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <asm/fpu/api.h>
 18#include <asm/simd.h>
 19
 20#define CHACHA20_STATE_ALIGN 16
 21
 22asmlinkage void chacha20_block_xor_ssse3(u32 *state, u8 *dst, const u8 *src);
 23asmlinkage void chacha20_4block_xor_ssse3(u32 *state, u8 *dst, const u8 *src);
 24#ifdef CONFIG_AS_AVX2
 25asmlinkage void chacha20_8block_xor_avx2(u32 *state, u8 *dst, const u8 *src);
 26static bool chacha20_use_avx2;
 27#endif
 28
 29static void chacha20_dosimd(u32 *state, u8 *dst, const u8 *src,
 30			    unsigned int bytes)
 31{
 32	u8 buf[CHACHA20_BLOCK_SIZE];
 33
 34#ifdef CONFIG_AS_AVX2
 35	if (chacha20_use_avx2) {
 36		while (bytes >= CHACHA20_BLOCK_SIZE * 8) {
 37			chacha20_8block_xor_avx2(state, dst, src);
 38			bytes -= CHACHA20_BLOCK_SIZE * 8;
 39			src += CHACHA20_BLOCK_SIZE * 8;
 40			dst += CHACHA20_BLOCK_SIZE * 8;
 41			state[12] += 8;
 42		}
 43	}
 44#endif
 45	while (bytes >= CHACHA20_BLOCK_SIZE * 4) {
 46		chacha20_4block_xor_ssse3(state, dst, src);
 47		bytes -= CHACHA20_BLOCK_SIZE * 4;
 48		src += CHACHA20_BLOCK_SIZE * 4;
 49		dst += CHACHA20_BLOCK_SIZE * 4;
 50		state[12] += 4;
 51	}
 52	while (bytes >= CHACHA20_BLOCK_SIZE) {
 53		chacha20_block_xor_ssse3(state, dst, src);
 54		bytes -= CHACHA20_BLOCK_SIZE;
 55		src += CHACHA20_BLOCK_SIZE;
 56		dst += CHACHA20_BLOCK_SIZE;
 57		state[12]++;
 58	}
 59	if (bytes) {
 60		memcpy(buf, src, bytes);
 61		chacha20_block_xor_ssse3(state, buf, buf);
 62		memcpy(dst, buf, bytes);
 63	}
 64}
 65
 66static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst,
 67			 struct scatterlist *src, unsigned int nbytes)
 68{
 69	u32 *state, state_buf[16 + (CHACHA20_STATE_ALIGN / sizeof(u32)) - 1];
 70	struct blkcipher_walk walk;
 71	int err;
 72
 73	if (nbytes <= CHACHA20_BLOCK_SIZE || !may_use_simd())
 74		return crypto_chacha20_crypt(desc, dst, src, nbytes);
 75
 76	state = (u32 *)roundup((uintptr_t)state_buf, CHACHA20_STATE_ALIGN);
 77
 78	blkcipher_walk_init(&walk, dst, src, nbytes);
 79	err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
 80
 81	crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
 82
 83	kernel_fpu_begin();
 84
 85	while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
 86		chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
 87				rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
 88		err = blkcipher_walk_done(desc, &walk,
 89					  walk.nbytes % CHACHA20_BLOCK_SIZE);
 90	}
 91
 92	if (walk.nbytes) {
 93		chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
 94				walk.nbytes);
 95		err = blkcipher_walk_done(desc, &walk, 0);
 96	}
 97
 98	kernel_fpu_end();
 99
100	return err;
101}
102
103static struct crypto_alg alg = {
104	.cra_name		= "chacha20",
105	.cra_driver_name	= "chacha20-simd",
106	.cra_priority		= 300,
107	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER,
108	.cra_blocksize		= 1,
109	.cra_type		= &crypto_blkcipher_type,
110	.cra_ctxsize		= sizeof(struct chacha20_ctx),
111	.cra_alignmask		= sizeof(u32) - 1,
112	.cra_module		= THIS_MODULE,
113	.cra_u			= {
114		.blkcipher = {
115			.min_keysize	= CHACHA20_KEY_SIZE,
116			.max_keysize	= CHACHA20_KEY_SIZE,
117			.ivsize		= CHACHA20_IV_SIZE,
118			.geniv		= "seqiv",
119			.setkey		= crypto_chacha20_setkey,
120			.encrypt	= chacha20_simd,
121			.decrypt	= chacha20_simd,
122		},
123	},
124};
125
126static int __init chacha20_simd_mod_init(void)
127{
128	if (!boot_cpu_has(X86_FEATURE_SSSE3))
129		return -ENODEV;
130
131#ifdef CONFIG_AS_AVX2
132	chacha20_use_avx2 = boot_cpu_has(X86_FEATURE_AVX) &&
133			    boot_cpu_has(X86_FEATURE_AVX2) &&
134			    cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL);
135#endif
136	return crypto_register_alg(&alg);
137}
138
139static void __exit chacha20_simd_mod_fini(void)
140{
141	crypto_unregister_alg(&alg);
142}
143
144module_init(chacha20_simd_mod_init);
145module_exit(chacha20_simd_mod_fini);
146
147MODULE_LICENSE("GPL");
148MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
149MODULE_DESCRIPTION("chacha20 cipher algorithm, SIMD accelerated");
150MODULE_ALIAS_CRYPTO("chacha20");
151MODULE_ALIAS_CRYPTO("chacha20-simd");