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

   1 /*
   2  * ChaCha20 256-bit cipher algorithm, RFC7539, ARM NEON functions
   3  *
   4  * Copyright (C) 2016 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                 chacha20_4block_xor_neon(state, dst, src);
  41                 bytes -= CHACHA20_BLOCK_SIZE * 4;
  42                 src += CHACHA20_BLOCK_SIZE * 4;
  43                 dst += CHACHA20_BLOCK_SIZE * 4;
  44                 state[12] += 4;
  45         }
  46         while (bytes >= CHACHA20_BLOCK_SIZE) {
  47                 chacha20_block_xor_neon(state, dst, src);
  48                 bytes -= CHACHA20_BLOCK_SIZE;
  49                 src += CHACHA20_BLOCK_SIZE;
  50                 dst += CHACHA20_BLOCK_SIZE;
  51                 state[12]++;
  52         }
  53         if (bytes) {
  54                 memcpy(buf, src, bytes);
  55                 chacha20_block_xor_neon(state, buf, buf);
  56                 memcpy(dst, buf, bytes);
  57         }
  58 }
  59
  60 static int chacha20_neon(struct skcipher_request *req)
  61 {
  62         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
  63         struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm);
  64         struct skcipher_walk walk;
  65         u32 state[16];
  66         int err;
  67
  68         if (req->cryptlen <= CHACHA20_BLOCK_SIZE || !may_use_simd())
  69                 return crypto_chacha20_crypt(req);
  70
  71         err = skcipher_walk_virt(&walk, req, true);
  72
  73         crypto_chacha20_init(state, ctx, walk.iv);
  74
  75         kernel_neon_begin();
  76         while (walk.nbytes > 0) {
  77                 unsigned int nbytes = walk.nbytes;
  78
  79                 if (nbytes < walk.total)
  80                         nbytes = round_down(nbytes, walk.stride);
  81
  82                 chacha20_doneon(state, walk.dst.virt.addr, walk.src.virt.addr,
  83                                 nbytes);
  84                 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
  85         }
  86         kernel_neon_end();
  87
  88         return err;
  89 }
  90
  91 static struct skcipher_alg alg = {
  92         .base.cra_name          = "chacha20",
  93         .base.cra_driver_name   = "chacha20-neon",
  94         .base.cra_priority      = 300,
  95         .base.cra_blocksize     = 1,
  96         .base.cra_ctxsize       = sizeof(struct chacha20_ctx),
  97         .base.cra_module        = THIS_MODULE,
  98
  99         .min_keysize            = CHACHA20_KEY_SIZE,
 100         .max_keysize            = CHACHA20_KEY_SIZE,
 101         .ivsize                 = CHACHA20_IV_SIZE,
 102         .chunksize              = CHACHA20_BLOCK_SIZE,
 103         .walksize               = 4 * CHACHA20_BLOCK_SIZE,
 104         .setkey                 = crypto_chacha20_setkey,
 105         .encrypt                = chacha20_neon,
 106         .decrypt                = chacha20_neon,
 107 };
 108
 109 static int __init chacha20_simd_mod_init(void)
 110 {
 111         if (!(elf_hwcap & HWCAP_NEON))
 112                 return -ENODEV;
 113
 114         return crypto_register_skcipher(&alg);
 115 }
 116
 117 static void __exit chacha20_simd_mod_fini(void)
 118 {
 119         crypto_unregister_skcipher(&alg);
 120 }
 121
 122 module_init(chacha20_simd_mod_init);
 123 module_exit(chacha20_simd_mod_fini);
 124
 125 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 126 MODULE_LICENSE("GPL v2");
 127 MODULE_ALIAS_CRYPTO("chacha20");