arch/x86/crypto/chacha20_glue.c

   1 /*
   2  * ChaCha20 256-bit cipher algorithm, RFC7539, SIMD glue code
   3  *
   4  * Copyright (C) 2015 Martin Willi
   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 as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11
  12 #include <crypto/algapi.h>
  13 #include <crypto/chacha20.h>
  14 #include <linux/crypto.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <asm/fpu/api.h>
  18 #include <asm/simd.h>
  19
  20 #define CHACHA20_STATE_ALIGN 16
  21
  22 asmlinkage void chacha20_block_xor_ssse3(u32 *state, u8 *dst, const u8 *src);
  23 asmlinkage void chacha20_4block_xor_ssse3(u32 *state, u8 *dst, const u8 *src);
  24 #ifdef CONFIG_AS_AVX2
  25 asmlinkage void chacha20_8block_xor_avx2(u32 *state, u8 *dst, const u8 *src);
  26 static bool chacha20_use_avx2;
  27 #endif
  28
  29 static void chacha20_dosimd(u32 *state, u8 *dst, const u8 *src,
  30                             unsigned int bytes)
  31 {
  32         u8 buf[CHACHA20_BLOCK_SIZE];
  33
  34 #ifdef CONFIG_AS_AVX2
  35         if (chacha20_use_avx2) {
  36                 while (bytes >= CHACHA20_BLOCK_SIZE * 8) {
  37                         chacha20_8block_xor_avx2(state, dst, src);
  38                         bytes -= CHACHA20_BLOCK_SIZE * 8;
  39                         src += CHACHA20_BLOCK_SIZE * 8;
  40                         dst += CHACHA20_BLOCK_SIZE * 8;
  41                         state[12] += 8;
  42                 }
  43         }
  44 #endif
  45         while (bytes >= CHACHA20_BLOCK_SIZE * 4) {
  46                 chacha20_4block_xor_ssse3(state, dst, src);
  47                 bytes -= CHACHA20_BLOCK_SIZE * 4;
  48                 src += CHACHA20_BLOCK_SIZE * 4;
  49                 dst += CHACHA20_BLOCK_SIZE * 4;
  50                 state[12] += 4;
  51         }
  52         while (bytes >= CHACHA20_BLOCK_SIZE) {
  53                 chacha20_block_xor_ssse3(state, dst, src);
  54                 bytes -= CHACHA20_BLOCK_SIZE;
  55                 src += CHACHA20_BLOCK_SIZE;
  56                 dst += CHACHA20_BLOCK_SIZE;
  57                 state[12]++;
  58         }
  59         if (bytes) {
  60                 memcpy(buf, src, bytes);
  61                 chacha20_block_xor_ssse3(state, buf, buf);
  62                 memcpy(dst, buf, bytes);
  63         }
  64 }
  65
  66 static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst,
  67                          struct scatterlist *src, unsigned int nbytes)
  68 {
  69         u32 *state, state_buf[16 + (CHACHA20_STATE_ALIGN / sizeof(u32)) - 1];
  70         struct blkcipher_walk walk;
  71         int err;
  72
  73         if (!may_use_simd())
  74                 return crypto_chacha20_crypt(desc, dst, src, nbytes);
  75
  76         state = (u32 *)roundup((uintptr_t)state_buf, CHACHA20_STATE_ALIGN);
  77
  78         blkcipher_walk_init(&walk, dst, src, nbytes);
  79         err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE);
  80
  81         crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv);
  82
  83         kernel_fpu_begin();
  84
  85         while (walk.nbytes >= CHACHA20_BLOCK_SIZE) {
  86                 chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
  87                                 rounddown(walk.nbytes, CHACHA20_BLOCK_SIZE));
  88                 err = blkcipher_walk_done(desc, &walk,
  89                                           walk.nbytes % CHACHA20_BLOCK_SIZE);
  90         }
  91
  92         if (walk.nbytes) {
  93                 chacha20_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
  94                                 walk.nbytes);
  95                 err = blkcipher_walk_done(desc, &walk, 0);
  96         }
  97
  98         kernel_fpu_end();
  99
 100         return err;
 101 }
 102
 103 static struct crypto_alg alg = {
 104         .cra_name               = "chacha20",
 105         .cra_driver_name        = "chacha20-simd",
 106         .cra_priority           = 300,
 107         .cra_flags              = CRYPTO_ALG_TYPE_BLKCIPHER,
 108         .cra_blocksize          = 1,
 109         .cra_type               = &crypto_blkcipher_type,
 110         .cra_ctxsize            = sizeof(struct chacha20_ctx),
 111         .cra_alignmask          = sizeof(u32) - 1,
 112         .cra_module             = THIS_MODULE,
 113         .cra_u                  = {
 114                 .blkcipher = {
 115                         .min_keysize    = CHACHA20_KEY_SIZE,
 116                         .max_keysize    = CHACHA20_KEY_SIZE,
 117                         .ivsize         = CHACHA20_IV_SIZE,
 118                         .geniv          = "seqiv",
 119                         .setkey         = crypto_chacha20_setkey,
 120                         .encrypt        = chacha20_simd,
 121                         .decrypt        = chacha20_simd,
 122                 },
 123         },
 124 };
 125
 126 static int __init chacha20_simd_mod_init(void)
 127 {
 128         if (!cpu_has_ssse3)
 129                 return -ENODEV;
 130
 131 #ifdef CONFIG_AS_AVX2
 132         chacha20_use_avx2 = cpu_has_avx && cpu_has_avx2 &&
 133                             cpu_has_xfeatures(XFEATURE_MASK_SSE | XFEATURE_MASK_YMM, NULL);
 134 #endif
 135         return crypto_register_alg(&alg);
 136 }
 137
 138 static void __exit chacha20_simd_mod_fini(void)
 139 {
 140         crypto_unregister_alg(&alg);
 141 }
 142
 143 module_init(chacha20_simd_mod_init);
 144 module_exit(chacha20_simd_mod_fini);
 145
 146 MODULE_LICENSE("GPL");
 147 MODULE_AUTHOR("Martin Willi <martin@strongswan.org>");
 148 MODULE_DESCRIPTION("chacha20 cipher algorithm, SIMD accelerated");
 149 MODULE_ALIAS_CRYPTO("chacha20");
 150 MODULE_ALIAS_CRYPTO("chacha20-simd");