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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/lib/crypto/arm64/chacha-neon-glue.c
26285 views
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/*

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 * ChaCha and HChaCha functions (ARM64 optimized)

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 *

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 * Copyright (C) 2016 - 2017 Linaro, Ltd. <[email protected]>

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 *

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License version 2 as

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 * published by the Free Software Foundation.

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 *

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 * Based on:

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 * ChaCha20 256-bit cipher algorithm, RFC7539, SIMD glue code

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 *

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 * Copyright (C) 2015 Martin Willi

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 *

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License as published by

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 * the Free Software Foundation; either version 2 of the License, or

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 * (at your option) any later version.

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 */

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#include <crypto/chacha.h>

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#include <crypto/internal/simd.h>

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#include <linux/jump_label.h>

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#include <linux/kernel.h>

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#include <linux/module.h>

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#include <asm/hwcap.h>

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#include <asm/neon.h>

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#include <asm/simd.h>

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asmlinkage void chacha_block_xor_neon(const struct chacha_state *state,

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				      u8 *dst, const u8 *src, int nrounds);

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asmlinkage void chacha_4block_xor_neon(const struct chacha_state *state,

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				       u8 *dst, const u8 *src,

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				       int nrounds, int bytes);

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asmlinkage void hchacha_block_neon(const struct chacha_state *state,

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				   u32 out[HCHACHA_OUT_WORDS], int nrounds);

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static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);

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static void chacha_doneon(struct chacha_state *state, u8 *dst, const u8 *src,

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			  int bytes, int nrounds)

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{

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	while (bytes > 0) {

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		int l = min(bytes, CHACHA_BLOCK_SIZE * 5);

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		if (l <= CHACHA_BLOCK_SIZE) {

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			u8 buf[CHACHA_BLOCK_SIZE];

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			memcpy(buf, src, l);

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			chacha_block_xor_neon(state, buf, buf, nrounds);

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			memcpy(dst, buf, l);

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			state->x[12] += 1;

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			break;

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		}

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		chacha_4block_xor_neon(state, dst, src, nrounds, l);

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		bytes -= l;

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		src += l;

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		dst += l;

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		state->x[12] += DIV_ROUND_UP(l, CHACHA_BLOCK_SIZE);

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	}

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}

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void hchacha_block_arch(const struct chacha_state *state,

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			u32 out[HCHACHA_OUT_WORDS], int nrounds)

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{

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	if (!static_branch_likely(&have_neon) || !crypto_simd_usable()) {

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		hchacha_block_generic(state, out, nrounds);

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	} else {

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		kernel_neon_begin();

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		hchacha_block_neon(state, out, nrounds);

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		kernel_neon_end();

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	}

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}

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EXPORT_SYMBOL(hchacha_block_arch);

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void chacha_crypt_arch(struct chacha_state *state, u8 *dst, const u8 *src,

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		       unsigned int bytes, int nrounds)

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{

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	if (!static_branch_likely(&have_neon) || bytes <= CHACHA_BLOCK_SIZE ||

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	    !crypto_simd_usable())

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		return chacha_crypt_generic(state, dst, src, bytes, nrounds);

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	do {

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		unsigned int todo = min_t(unsigned int, bytes, SZ_4K);

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		kernel_neon_begin();

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		chacha_doneon(state, dst, src, todo, nrounds);

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		kernel_neon_end();

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		bytes -= todo;

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		src += todo;

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		dst += todo;

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	} while (bytes);

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}

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EXPORT_SYMBOL(chacha_crypt_arch);

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bool chacha_is_arch_optimized(void)

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{

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	return static_key_enabled(&have_neon);

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}

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EXPORT_SYMBOL(chacha_is_arch_optimized);

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static int __init chacha_simd_mod_init(void)

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{

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	if (cpu_have_named_feature(ASIMD))

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		static_branch_enable(&have_neon);

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	return 0;

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}

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subsys_initcall(chacha_simd_mod_init);

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static void __exit chacha_simd_mod_exit(void)

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{

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}

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module_exit(chacha_simd_mod_exit);

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MODULE_DESCRIPTION("ChaCha and HChaCha functions (ARM64 optimized)");

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MODULE_AUTHOR("Ard Biesheuvel <[email protected]>");

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MODULE_LICENSE("GPL v2");

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