arch/x86/crypto/crc32c-intel_glue.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 Intel Corporation
  10  * Authors: Austin Zhang <austin_zhang@linux.intel.com>
  11  *          Kent Liu <kent.liu@intel.com>
  12  *
  13  * This program is free software; you can redistribute it and/or modify it
  14  * under the terms and conditions of the GNU General Public License,
  15  * version 2, as published by the Free Software Foundation.
  16  *
  17  * This program is distributed in the hope it will be useful, but WITHOUT
  18  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  19  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  20  * more details.
  21  *
  22  * You should have received a copy of the GNU General Public License along with
  23  * this program; if not, write to the Free Software Foundation, Inc.,
  24  * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  25  *
  26  */
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/string.h>
  30 #include <linux/kernel.h>
  31 #include <crypto/internal/hash.h>
  32
  33 #include <asm/cpufeature.h>
  34 #include <asm/cpu_device_id.h>
  35 #include <asm/i387.h>
  36 #include <asm/fpu-internal.h>
  37
  38 #define CHKSUM_BLOCK_SIZE       1
  39 #define CHKSUM_DIGEST_SIZE      4
  40
  41 #define SCALE_F sizeof(unsigned long)
  42
  43 #ifdef CONFIG_X86_64
  44 #define REX_PRE "0x48, "
  45 #else
  46 #define REX_PRE
  47 #endif
  48
  49 #ifdef CONFIG_X86_64
  50 /*
  51  * use carryless multiply version of crc32c when buffer
  52  * size is >= 512 (when eager fpu is enabled) or
  53  * >= 1024 (when eager fpu is disabled) to account
  54  * for fpu state save/restore overhead.
  55  */
  56 #define CRC32C_PCL_BREAKEVEN_EAGERFPU   512
  57 #define CRC32C_PCL_BREAKEVEN_NOEAGERFPU 1024
  58
  59 asmlinkage unsigned int crc_pcl(const u8 *buffer, int len,
  60                                 unsigned int crc_init);
  61 static int crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_EAGERFPU;
  62 #if defined(X86_FEATURE_EAGER_FPU)
  63 #define set_pcl_breakeven_point()                                       \
  64 do {                                                                    \
  65         if (!use_eager_fpu())                                           \
  66                 crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU; \
  67 } while (0)
  68 #else
  69 #define set_pcl_breakeven_point()                                       \
  70         (crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU)
  71 #endif
  72 #endif /* CONFIG_X86_64 */
  73
  74 static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
  75 {
  76         while (length--) {
  77                 __asm__ __volatile__(
  78                         ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
  79                         :"=S"(crc)
  80                         :"0"(crc), "c"(*data)
  81                 );
  82                 data++;
  83         }
  84
  85         return crc;
  86 }
  87
  88 static u32 __pure crc32c_intel_le_hw(u32 crc, unsigned char const *p, size_t len)
  89 {
  90         unsigned int iquotient = len / SCALE_F;
  91         unsigned int iremainder = len % SCALE_F;
  92         unsigned long *ptmp = (unsigned long *)p;
  93
  94         while (iquotient--) {
  95                 __asm__ __volatile__(
  96                         ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
  97                         :"=S"(crc)
  98                         :"0"(crc), "c"(*ptmp)
  99                 );
 100                 ptmp++;
 101         }
 102
 103         if (iremainder)
 104                 crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
 105                                  iremainder);
 106
 107         return crc;
 108 }
 109
 110 /*
 111  * Setting the seed allows arbitrary accumulators and flexible XOR policy
 112  * If your algorithm starts with ~0, then XOR with ~0 before you set
 113  * the seed.
 114  */
 115 static int crc32c_intel_setkey(struct crypto_shash *hash, const u8 *key,
 116                         unsigned int keylen)
 117 {
 118         u32 *mctx = crypto_shash_ctx(hash);
 119
 120         if (keylen != sizeof(u32)) {
 121                 crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
 122                 return -EINVAL;
 123         }
 124         *mctx = le32_to_cpup((__le32 *)key);
 125         return 0;
 126 }
 127
 128 static int crc32c_intel_init(struct shash_desc *desc)
 129 {
 130         u32 *mctx = crypto_shash_ctx(desc->tfm);
 131         u32 *crcp = shash_desc_ctx(desc);
 132
 133         *crcp = *mctx;
 134
 135         return 0;
 136 }
 137
 138 static int crc32c_intel_update(struct shash_desc *desc, const u8 *data,
 139                                unsigned int len)
 140 {
 141         u32 *crcp = shash_desc_ctx(desc);
 142
 143         *crcp = crc32c_intel_le_hw(*crcp, data, len);
 144         return 0;
 145 }
 146
 147 static int __crc32c_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
 148                                 u8 *out)
 149 {
 150         *(__le32 *)out = ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
 151         return 0;
 152 }
 153
 154 static int crc32c_intel_finup(struct shash_desc *desc, const u8 *data,
 155                               unsigned int len, u8 *out)
 156 {
 157         return __crc32c_intel_finup(shash_desc_ctx(desc), data, len, out);
 158 }
 159
 160 static int crc32c_intel_final(struct shash_desc *desc, u8 *out)
 161 {
 162         u32 *crcp = shash_desc_ctx(desc);
 163
 164         *(__le32 *)out = ~cpu_to_le32p(crcp);
 165         return 0;
 166 }
 167
 168 static int crc32c_intel_digest(struct shash_desc *desc, const u8 *data,
 169                                unsigned int len, u8 *out)
 170 {
 171         return __crc32c_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
 172                                     out);
 173 }
 174
 175 static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
 176 {
 177         u32 *key = crypto_tfm_ctx(tfm);
 178
 179         *key = ~0;
 180
 181         return 0;
 182 }
 183
 184 #ifdef CONFIG_X86_64
 185 static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
 186                                unsigned int len)
 187 {
 188         u32 *crcp = shash_desc_ctx(desc);
 189
 190         /*
 191          * use faster PCL version if datasize is large enough to
 192          * overcome kernel fpu state save/restore overhead
 193          */
 194         if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) {
 195                 kernel_fpu_begin();
 196                 *crcp = crc_pcl(data, len, *crcp);
 197                 kernel_fpu_end();
 198         } else
 199                 *crcp = crc32c_intel_le_hw(*crcp, data, len);
 200         return 0;
 201 }
 202
 203 static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
 204                                 u8 *out)
 205 {
 206         if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) {
 207                 kernel_fpu_begin();
 208                 *(__le32 *)out = ~cpu_to_le32(crc_pcl(data, len, *crcp));
 209                 kernel_fpu_end();
 210         } else
 211                 *(__le32 *)out =
 212                         ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
 213         return 0;
 214 }
 215
 216 static int crc32c_pcl_intel_finup(struct shash_desc *desc, const u8 *data,
 217                               unsigned int len, u8 *out)
 218 {
 219         return __crc32c_pcl_intel_finup(shash_desc_ctx(desc), data, len, out);
 220 }
 221
 222 static int crc32c_pcl_intel_digest(struct shash_desc *desc, const u8 *data,
 223                                unsigned int len, u8 *out)
 224 {
 225         return __crc32c_pcl_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
 226                                     out);
 227 }
 228 #endif /* CONFIG_X86_64 */
 229
 230 static struct shash_alg alg = {
 231         .setkey                 =       crc32c_intel_setkey,
 232         .init                   =       crc32c_intel_init,
 233         .update                 =       crc32c_intel_update,
 234         .final                  =       crc32c_intel_final,
 235         .finup                  =       crc32c_intel_finup,
 236         .digest                 =       crc32c_intel_digest,
 237         .descsize               =       sizeof(u32),
 238         .digestsize             =       CHKSUM_DIGEST_SIZE,
 239         .base                   =       {
 240                 .cra_name               =       "crc32c",
 241                 .cra_driver_name        =       "crc32c-intel",
 242                 .cra_priority           =       200,
 243                 .cra_blocksize          =       CHKSUM_BLOCK_SIZE,
 244                 .cra_ctxsize            =       sizeof(u32),
 245                 .cra_module             =       THIS_MODULE,
 246                 .cra_init               =       crc32c_intel_cra_init,
 247         }
 248 };
 249
 250 static const struct x86_cpu_id crc32c_cpu_id[] = {
 251         X86_FEATURE_MATCH(X86_FEATURE_XMM4_2),
 252         {}
 253 };
 254 MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
 255
 256 static int __init crc32c_intel_mod_init(void)
 257 {
 258         if (!x86_match_cpu(crc32c_cpu_id))
 259                 return -ENODEV;
 260 #ifdef CONFIG_X86_64
 261         if (cpu_has_pclmulqdq) {
 262                 alg.update = crc32c_pcl_intel_update;
 263                 alg.finup = crc32c_pcl_intel_finup;
 264                 alg.digest = crc32c_pcl_intel_digest;
 265                 set_pcl_breakeven_point();
 266         }
 267 #endif
 268         return crypto_register_shash(&alg);
 269 }
 270
 271 static void __exit crc32c_intel_mod_fini(void)
 272 {
 273         crypto_unregister_shash(&alg);
 274 }
 275
 276 module_init(crc32c_intel_mod_init);
 277 module_exit(crc32c_intel_mod_fini);
 278
 279 MODULE_AUTHOR("Austin Zhang <austin.zhang@intel.com>, Kent Liu <kent.liu@intel.com>");
 280 MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
 281 MODULE_LICENSE("GPL");
 282
 283 MODULE_ALIAS("crc32c");
 284 MODULE_ALIAS("crc32c-intel");