text: // SPDX-License-Identifier: GPL-2.0
  /*
   * MIPS accelerated ChaCha and XChaCha stream ciphers,
   * including ChaCha20 (RFC7539)
   *
   * Copyright (C) 2019 Linaro, Ltd. <ard.biesheuvel@linaro.org>
   */
  
  #include <asm/byteorder.h>
  #include <crypto/algapi.h>
  #include <crypto/internal/chacha.h>
  #include <crypto/internal/skcipher.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  
  asmlinkage void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
  				  unsigned int bytes, int nrounds);
  EXPORT_SYMBOL(chacha_crypt_arch);
  
  asmlinkage void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds);
  EXPORT_SYMBOL(hchacha_block_arch);
  
  void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
  {
  	chacha_init_generic(state, key, iv);
  }
  EXPORT_SYMBOL(chacha_init_arch);
  
  static int chacha_mips_stream_xor(struct skcipher_request *req,
  				  const struct chacha_ctx *ctx, const u8 *iv)
  {
  	struct skcipher_walk walk;
  	u32 state[16];
  	int err;
  
  	err = skcipher_walk_virt(&walk, req, false);
  
  	chacha_init_generic(state, ctx->key, iv);
  
  	while (walk.nbytes > 0) {
  		unsigned int nbytes = walk.nbytes;
  
  		if (nbytes < walk.total)
  			nbytes = round_down(nbytes, walk.stride);
  
  		chacha_crypt(state, walk.dst.virt.addr, walk.src.virt.addr,
  			     nbytes, ctx->nrounds);
  		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
  	}
  
  	return err;
  }
  
  static int chacha_mips(struct skcipher_request *req)
  {
  	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
  
  	return chacha_mips_stream_xor(req, ctx, req->iv);
  }
  
  static int xchacha_mips(struct skcipher_request *req)
  {
  	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  	struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
  	struct chacha_ctx subctx;
  	u32 state[16];
  	u8 real_iv[16];
  
  	chacha_init_generic(state, ctx->key, req->iv);
  
  	hchacha_block(state, subctx.key, ctx->nrounds);
  	subctx.nrounds = ctx->nrounds;
  
  	memcpy(&real_iv[0], req->iv + 24, 8);
  	memcpy(&real_iv[8], req->iv + 16, 8);
  	return chacha_mips_stream_xor(req, &subctx, real_iv);
  }
  
  static struct skcipher_alg algs[] = {
  	{
  		.base.cra_name		= "chacha20",
  		.base.cra_driver_name	= "chacha20-mips",
  		.base.cra_priority	= 200,
  		.base.cra_blocksize	= 1,
  		.base.cra_ctxsize	= sizeof(struct chacha_ctx),
  		.base.cra_module	= THIS_MODULE,
  
  		.min_keysize		= CHACHA_KEY_SIZE,
  		.max_keysize		= CHACHA_KEY_SIZE,
  		.ivsize			= CHACHA_IV_SIZE,
  		.chunksize		= CHACHA_BLOCK_SIZE,
  		.setkey			= chacha20_setkey,
  		.encrypt		= chacha_mips,
  		.decrypt		= chacha_mips,
  	}, {
  		.base.cra_name		= "xchacha20",
  		.base.cra_driver_name	= "xchacha20-mips",
  		.base.cra_priority	= 200,
  		.base.cra_blocksize	= 1,
  		.base.cra_ctxsize	= sizeof(struct chacha_ctx),
  		.base.cra_module	= THIS_MODULE,
  
  		.min_keysize		= CHACHA_KEY_SIZE,
  		.max_keysize		= CHACHA_KEY_SIZE,
  		.ivsize			= XCHACHA_IV_SIZE,
  		.chunksize		= CHACHA_BLOCK_SIZE,
  		.setkey			= chacha20_setkey,
  		.encrypt		= xchacha_mips,
  		.decrypt		= xchacha_mips,
  	}, {
  		.base.cra_name		= "xchacha12",
  		.base.cra_driver_name	= "xchacha12-mips",
  		.base.cra_priority	= 200,
  		.base.cra_blocksize	= 1,
  		.base.cra_ctxsize	= sizeof(struct chacha_ctx),
  		.base.cra_module	= THIS_MODULE,
  
  		.min_keysize		= CHACHA_KEY_SIZE,
  		.max_keysize		= CHACHA_KEY_SIZE,
  		.ivsize			= XCHACHA_IV_SIZE,
  		.chunksize		= CHACHA_BLOCK_SIZE,
  		.setkey			= chacha12_setkey,
  		.encrypt		= xchacha_mips,
  		.decrypt		= xchacha_mips,
  	}
  };
  
  static int __init chacha_simd_mod_init(void)
  {
  	return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
  		crypto_register_skciphers(algs, ARRAY_SIZE(algs)) : 0;
  }
  
  static void __exit chacha_simd_mod_fini(void)
  {
  	if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER))
  		crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
  }
  
  module_init(chacha_simd_mod_init);
  module_exit(chacha_simd_mod_fini);
  
  MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (MIPS accelerated)");
  MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
  MODULE_LICENSE("GPL v2");
  MODULE_ALIAS_CRYPTO("chacha20");
  MODULE_ALIAS_CRYPTO("chacha20-mips");
  MODULE_ALIAS_CRYPTO("xchacha20");
  MODULE_ALIAS_CRYPTO("xchacha20-mips");
  MODULE_ALIAS_CRYPTO("xchacha12");
  MODULE_ALIAS_CRYPTO("xchacha12-mips");
  