arch/x86/crypto/crc32c-intel.c

   1 /*
   2  * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
   3  * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
   4  * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
   5  * http://www.intel.com/products/processor/manuals/
   6  * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
   7  * Volume 2A: Instruction Set Reference, A-M
   8  *
   9  * Copyright (c) 2008 Austin Zhang <austin_zhang@linux.intel.com>
  10  * Copyright (c) 2008 Kent Liu <kent.liu@intel.com>
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU General Public License as published by the Free
  14  * Software Foundation; either version 2 of the License, or (at your option)
  15  * any later version.
  16  *
  17  */
  18 #include <linux/init.h>
  19 #include <linux/module.h>
  20 #include <linux/string.h>
  21 #include <linux/kernel.h>
  22 #include <crypto/internal/hash.h>
  23
  24 #include <asm/cpufeature.h>
  25
  26 #define CHKSUM_BLOCK_SIZE       1
  27 #define CHKSUM_DIGEST_SIZE      4
  28
  29 #define SCALE_F sizeof(unsigned long)
  30
  31 #ifdef CONFIG_X86_64
  32 #define REX_PRE "0x48, "
  33 #else
  34 #define REX_PRE
  35 #endif
  36
  37 static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
  38 {
  39         while (length--) {
  40                 __asm__ __volatile__(
  41                         ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
  42                         :"=S"(crc)
  43                         :"0"(crc), "c"(*data)
  44                 );
  45                 data++;
  46         }
  47
  48         return crc;
  49 }
  50
  51 static u32 __pure crc32c_intel_le_hw(u32 crc, unsigned char const *p, size_t len)
  52 {
  53         unsigned int iquotient = len / SCALE_F;
  54         unsigned int iremainder = len % SCALE_F;
  55         unsigned long *ptmp = (unsigned long *)p;
  56
  57         while (iquotient--) {
  58                 __asm__ __volatile__(
  59                         ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
  60                         :"=S"(crc)
  61                         :"0"(crc), "c"(*ptmp)
  62                 );
  63                 ptmp++;
  64         }
  65
  66         if (iremainder)
  67                 crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
  68                                  iremainder);
  69
  70         return crc;
  71 }
  72
  73 /*
  74  * Setting the seed allows arbitrary accumulators and flexible XOR policy
  75  * If your algorithm starts with ~0, then XOR with ~0 before you set
  76  * the seed.
  77  */
  78 static int crc32c_intel_setkey(struct crypto_ahash *hash, const u8 *key,
  79                         unsigned int keylen)
  80 {
  81         u32 *mctx = crypto_ahash_ctx(hash);
  82
  83         if (keylen != sizeof(u32)) {
  84                 crypto_ahash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
  85                 return -EINVAL;
  86         }
  87         *mctx = le32_to_cpup((__le32 *)key);
  88         return 0;
  89 }
  90
  91 static int crc32c_intel_init(struct ahash_request *req)
  92 {
  93         u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
  94         u32 *crcp = ahash_request_ctx(req);
  95
  96         *crcp = *mctx;
  97
  98         return 0;
  99 }
 100
 101 static int crc32c_intel_update(struct ahash_request *req)
 102 {
 103         struct crypto_hash_walk walk;
 104         u32 *crcp = ahash_request_ctx(req);
 105         u32 crc = *crcp;
 106         int nbytes;
 107
 108         for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
 109            nbytes = crypto_hash_walk_done(&walk, 0))
 110         crc = crc32c_intel_le_hw(crc, walk.data, nbytes);
 111
 112         *crcp = crc;
 113         return 0;
 114 }
 115
 116 static int crc32c_intel_final(struct ahash_request *req)
 117 {
 118         u32 *crcp = ahash_request_ctx(req);
 119
 120         *(__le32 *)req->result = ~cpu_to_le32p(crcp);
 121         return 0;
 122 }
 123
 124 static int crc32c_intel_digest(struct ahash_request *req)
 125 {
 126         struct crypto_hash_walk walk;
 127         u32 *mctx = crypto_ahash_ctx(crypto_ahash_reqtfm(req));
 128         u32 crc = *mctx;
 129         int nbytes;
 130
 131         for (nbytes = crypto_hash_walk_first(req, &walk); nbytes;
 132            nbytes = crypto_hash_walk_done(&walk, 0))
 133                 crc = crc32c_intel_le_hw(crc, walk.data, nbytes);
 134
 135         *(__le32 *)req->result = ~cpu_to_le32(crc);
 136         return 0;
 137 }
 138
 139 static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
 140 {
 141         u32 *key = crypto_tfm_ctx(tfm);
 142
 143         *key = ~0;
 144
 145         tfm->crt_ahash.reqsize = sizeof(u32);
 146
 147         return 0;
 148 }
 149
 150 static struct crypto_alg alg = {
 151         .cra_name               =       "crc32c",
 152         .cra_driver_name        =       "crc32c-intel",
 153         .cra_priority           =       200,
 154         .cra_flags              =       CRYPTO_ALG_TYPE_AHASH,
 155         .cra_blocksize          =       CHKSUM_BLOCK_SIZE,
 156         .cra_alignmask          =       3,
 157         .cra_ctxsize            =       sizeof(u32),
 158         .cra_module             =       THIS_MODULE,
 159         .cra_list               =       LIST_HEAD_INIT(alg.cra_list),
 160         .cra_init               =       crc32c_intel_cra_init,
 161         .cra_type               =       &crypto_ahash_type,
 162         .cra_u                  =       {
 163                 .ahash = {
 164                         .digestsize    =       CHKSUM_DIGEST_SIZE,
 165                         .setkey        =       crc32c_intel_setkey,
 166                         .init          =       crc32c_intel_init,
 167                         .update        =       crc32c_intel_update,
 168                         .final         =       crc32c_intel_final,
 169                         .digest        =       crc32c_intel_digest,
 170                 }
 171         }
 172 };
 173
 174
 175 static int __init crc32c_intel_mod_init(void)
 176 {
 177         if (cpu_has_xmm4_2)
 178                 return crypto_register_alg(&alg);
 179         else
 180                 return -ENODEV;
 181 }
 182
 183 static void __exit crc32c_intel_mod_fini(void)
 184 {
 185         crypto_unregister_alg(&alg);
 186 }
 187
 188 module_init(crc32c_intel_mod_init);
 189 module_exit(crc32c_intel_mod_fini);
 190
 191 MODULE_AUTHOR("Austin Zhang <austin.zhang@intel.com>, Kent Liu <kent.liu@intel.com>");
 192 MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
 193 MODULE_LICENSE("GPL");
 194
 195 MODULE_ALIAS("crc32c");
 196 MODULE_ALIAS("crc32c-intel");
 197