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/*
* ChaCha20 256-bit cipher algorithm, RFC7539, ARM NEON functions
*
* Copyright (C) 2016 Linaro, Ltd. <ard.biesheuvel@linaro.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Based on:
* ChaCha20 256-bit cipher algorithm, RFC7539, SIMD glue code
*
* Copyright (C) 2015 Martin Willi
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <crypto/algapi.h>
#include <crypto/chacha20.h>
#include <linux/crypto.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <asm/hwcap.h>
#include <asm/neon.h>
#include <asm/simd.h>
asmlinkage void chacha20_block_xor_neon(u32 *state, u8 *dst, const u8 *src);
asmlinkage void chacha20_4block_xor_neon(u32 *state, u8 *dst, const u8 *src);
static void chacha20_dosimd(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
{
u8 buf[CHACHA20_BLOCK_SIZE];
while (bytes >= CHACHA20_BLOCK_SIZE * 4) {
chacha20_4block_xor_neon(state, dst, src);
bytes -= CHACHA20_BLOCK_SIZE * 4;
src += CHACHA20_BLOCK_SIZE * 4;
dst += CHACHA20_BLOCK_SIZE * 4;
state[12] += 4;
}
while (bytes >= CHACHA20_BLOCK_SIZE) {
chacha20_block_xor_neon(state, dst, src);
bytes -= CHACHA20_BLOCK_SIZE;
src += CHACHA20_BLOCK_SIZE;
dst += CHACHA20_BLOCK_SIZE;
state[12]++;
}
if (bytes) {
memcpy(buf, src, bytes);
chacha20_block_xor_neon(state, buf, buf);
memcpy(dst, buf, bytes);
}
}
static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst,
struct scatterlist *src, unsigned int nbytes)
{
struct blkcipher_walk walk;
u32 state[16];
int err;
if (nbytes <= CHACHA20_BLOCK_SIZE || !may_use_simd())
return crypto_chacha20_crypt(desc, dst, src, nbytes);
blkcipher_walk_init(&walk, dst, src, nbytes);
err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
kernel_neon_begin();
while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
err = blkcipher_walk_done(desc, &walk,
walk.nbytes % CHACHA20_BLOCK_SIZE);
}
if (walk.nbytes) {
chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
walk.nbytes);
err = blkcipher_walk_done(desc, &walk, 0);
}
kernel_neon_end();
return err;
}
static struct crypto_alg alg = {
.cra_name = "chacha20",
.cra_driver_name = "chacha20-neon",
.cra_priority = 300,
.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER,
.cra_blocksize = 1,
.cra_type = &crypto_blkcipher_type,
.cra_ctxsize = sizeof(struct chacha20_ctx),
.cra_alignmask = sizeof(u32) - 1,
.cra_module = THIS_MODULE,
.cra_u = {
.blkcipher = {
.min_keysize = CHACHA20_KEY_SIZE,
.max_keysize = CHACHA20_KEY_SIZE,
.ivsize = CHACHA20_IV_SIZE,
.geniv = "seqiv",
.setkey = crypto_chacha20_setkey,
.encrypt = chacha20_simd,
.decrypt = chacha20_simd,
},
},
};
static int __init chacha20_simd_mod_init(void)
{
if (!(elf_hwcap & HWCAP_NEON))
return -ENODEV;
return crypto_register_alg(&alg);
}
static void __exit chacha20_simd_mod_fini(void)
{
crypto_unregister_alg(&alg);
}
module_init(chacha20_simd_mod_init);
module_exit(chacha20_simd_mod_fini);
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS_CRYPTO("chacha20");
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