arch/arm64/crypto/chacha20-neon-glue.c

   1 /*
   2  * ChaCha20 256-bit cipher algorithm, RFC7539, arm64 NEON functions
   3  *
   4  * Copyright (C) 2016 - 2017 Linaro, Ltd. <ard.biesheuvel@linaro.org>
   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 version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Based on:
  11  * ChaCha20 256-bit cipher algorithm, RFC7539, SIMD glue code
  12  *
  13  * Copyright (C) 2015 Martin Willi
  14  *
  15  * This program is free software; you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  */
  20
  21 #include <crypto/algapi.h>
  22 #include <crypto/chacha20.h>
  23 #include <crypto/internal/skcipher.h>
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26
  27 #include <asm/hwcap.h>
  28 #include <asm/neon.h>
  29 #include <asm/simd.h>
  30
  31 asmlinkage void chacha20_block_xor_neon(u32 *state, u8 *dst, const u8 *src);
  32 asmlinkage void chacha20_4block_xor_neon(u32 *state, u8 *dst, const u8 *src);
  33
  34 static void chacha20_doneon(u32 *state, u8 *dst, const u8 *src,
  35                             unsigned int bytes)
  36 {
  37         u8 buf[CHACHA20_BLOCK_SIZE];
  38
  39         while (bytes >= CHACHA20_BLOCK_SIZE * 4) {
  40                 kernel_neon_begin();
  41                 chacha20_4block_xor_neon(state, dst, src);
  42                 kernel_neon_end();
  43                 bytes -= CHACHA20_BLOCK_SIZE * 4;
  44                 src += CHACHA20_BLOCK_SIZE * 4;
  45                 dst += CHACHA20_BLOCK_SIZE * 4;
  46                 state[12] += 4;
  47         }
  48
  49         if (!bytes)
  50                 return;
  51
  52         kernel_neon_begin();
  53         while (bytes >= CHACHA20_BLOCK_SIZE) {
  54                 chacha20_block_xor_neon(state, dst, src);
  55                 bytes -= CHACHA20_BLOCK_SIZE;
  56                 src += CHACHA20_BLOCK_SIZE;
  57                 dst += CHACHA20_BLOCK_SIZE;
  58                 state[12]++;
  59         }
  60         if (bytes) {
  61                 memcpy(buf, src, bytes);
  62                 chacha20_block_xor_neon(state, buf, buf);
  63                 memcpy(dst, buf, bytes);
  64         }
  65         kernel_neon_end();
  66 }
  67
  68 static int chacha20_neon(struct skcipher_request *req)
  69 {
  70         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  71         struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
  72         struct skcipher_walk walk;
  73         u32 state[16];
  74         int err;
  75
  76         if (!may_use_simd() || req->cryptlen <= CHACHA20_BLOCK_SIZE)
  77                 return crypto_chacha20_crypt(req);
  78
  79         err = skcipher_walk_virt(&walk, req, false);
  80
  81         crypto_chacha20_init(state, ctx, walk.iv);
  82
  83         while (walk.nbytes > 0) {
  84                 unsigned int nbytes = walk.nbytes;
  85
  86                 if (nbytes < walk.total)
  87                         nbytes = round_down(nbytes, walk.stride);
  88
  89                 chacha20_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
  90                                 nbytes);
  91                 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
  92         }
  93
  94         return err;
  95 }
  96
  97 static struct skcipher_alg alg = {
  98         .base.cra_name          = "chacha20",
  99         .base.cra_driver_name   = "chacha20-neon",
 100         .base.cra_priority      = 300,
 101         .base.cra_blocksize     = 1,
 102         .base.cra_ctxsize       = sizeof(struct chacha20_ctx),
 103         .base.cra_module        = THIS_MODULE,
 104
 105         .min_keysize            = CHACHA20_KEY_SIZE,
 106         .max_keysize            = CHACHA20_KEY_SIZE,
 107         .ivsize                 = CHACHA20_IV_SIZE,
 108         .chunksize              = CHACHA20_BLOCK_SIZE,
 109         .walksize               = 4 * CHACHA20_BLOCK_SIZE,
 110         .setkey                 = crypto_chacha20_setkey,
 111         .encrypt                = chacha20_neon,
 112         .decrypt                = chacha20_neon,
 113 };
 114
 115 static int __init chacha20_simd_mod_init(void)
 116 {
 117         if (!(elf_hwcap & HWCAP_ASIMD))
 118                 return -ENODEV;
 119
 120         return crypto_register_skcipher(&alg);
 121 }
 122
 123 static void __exit chacha20_simd_mod_fini(void)
 124 {
 125         crypto_unregister_skcipher(&alg);
 126 }
 127
 128 module_init(chacha20_simd_mod_init);
 129 module_exit(chacha20_simd_mod_fini);
 130
 131 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 132 MODULE_LICENSE("GPL v2");
 133 MODULE_ALIAS_CRYPTO("chacha20");