linux/arch/x86/crypto/crc32c-intel_glue.c
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   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/cpufeatures.h>
  34#include <asm/cpu_device_id.h>
  35#include <asm/fpu/internal.h>
  36
  37#define CHKSUM_BLOCK_SIZE       1
  38#define CHKSUM_DIGEST_SIZE      4
  39
  40#define SCALE_F sizeof(unsigned long)
  41
  42#ifdef CONFIG_X86_64
  43#define REX_PRE "0x48, "
  44#else
  45#define REX_PRE
  46#endif
  47
  48#ifdef CONFIG_X86_64
  49/*
  50 * use carryless multiply version of crc32c when buffer
  51 * size is >= 512 to account
  52 * for fpu state save/restore overhead.
  53 */
  54#define CRC32C_PCL_BREAKEVEN    512
  55
  56asmlinkage unsigned int crc_pcl(const u8 *buffer, int len,
  57                                unsigned int crc_init);
  58#endif /* CONFIG_X86_64 */
  59
  60static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
  61{
  62        while (length--) {
  63                __asm__ __volatile__(
  64                        ".byte 0xf2, 0xf, 0x38, 0xf0, 0xf1"
  65                        :"=S"(crc)
  66                        :"0"(crc), "c"(*data)
  67                );
  68                data++;
  69        }
  70
  71        return crc;
  72}
  73
  74static u32 __pure crc32c_intel_le_hw(u32 crc, unsigned char const *p, size_t len)
  75{
  76        unsigned int iquotient = len / SCALE_F;
  77        unsigned int iremainder = len % SCALE_F;
  78        unsigned long *ptmp = (unsigned long *)p;
  79
  80        while (iquotient--) {
  81                __asm__ __volatile__(
  82                        ".byte 0xf2, " REX_PRE "0xf, 0x38, 0xf1, 0xf1;"
  83                        :"=S"(crc)
  84                        :"0"(crc), "c"(*ptmp)
  85                );
  86                ptmp++;
  87        }
  88
  89        if (iremainder)
  90                crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
  91                                 iremainder);
  92
  93        return crc;
  94}
  95
  96/*
  97 * Setting the seed allows arbitrary accumulators and flexible XOR policy
  98 * If your algorithm starts with ~0, then XOR with ~0 before you set
  99 * the seed.
 100 */
 101static int crc32c_intel_setkey(struct crypto_shash *hash, const u8 *key,
 102                        unsigned int keylen)
 103{
 104        u32 *mctx = crypto_shash_ctx(hash);
 105
 106        if (keylen != sizeof(u32)) {
 107                crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
 108                return -EINVAL;
 109        }
 110        *mctx = le32_to_cpup((__le32 *)key);
 111        return 0;
 112}
 113
 114static int crc32c_intel_init(struct shash_desc *desc)
 115{
 116        u32 *mctx = crypto_shash_ctx(desc->tfm);
 117        u32 *crcp = shash_desc_ctx(desc);
 118
 119        *crcp = *mctx;
 120
 121        return 0;
 122}
 123
 124static int crc32c_intel_update(struct shash_desc *desc, const u8 *data,
 125                               unsigned int len)
 126{
 127        u32 *crcp = shash_desc_ctx(desc);
 128
 129        *crcp = crc32c_intel_le_hw(*crcp, data, len);
 130        return 0;
 131}
 132
 133static int __crc32c_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
 134                                u8 *out)
 135{
 136        *(__le32 *)out = ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
 137        return 0;
 138}
 139
 140static int crc32c_intel_finup(struct shash_desc *desc, const u8 *data,
 141                              unsigned int len, u8 *out)
 142{
 143        return __crc32c_intel_finup(shash_desc_ctx(desc), data, len, out);
 144}
 145
 146static int crc32c_intel_final(struct shash_desc *desc, u8 *out)
 147{
 148        u32 *crcp = shash_desc_ctx(desc);
 149
 150        *(__le32 *)out = ~cpu_to_le32p(crcp);
 151        return 0;
 152}
 153
 154static int crc32c_intel_digest(struct shash_desc *desc, const u8 *data,
 155                               unsigned int len, u8 *out)
 156{
 157        return __crc32c_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
 158                                    out);
 159}
 160
 161static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
 162{
 163        u32 *key = crypto_tfm_ctx(tfm);
 164
 165        *key = ~0;
 166
 167        return 0;
 168}
 169
 170#ifdef CONFIG_X86_64
 171static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
 172                               unsigned int len)
 173{
 174        u32 *crcp = shash_desc_ctx(desc);
 175
 176        /*
 177         * use faster PCL version if datasize is large enough to
 178         * overcome kernel fpu state save/restore overhead
 179         */
 180        if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) {
 181                kernel_fpu_begin();
 182                *crcp = crc_pcl(data, len, *crcp);
 183                kernel_fpu_end();
 184        } else
 185                *crcp = crc32c_intel_le_hw(*crcp, data, len);
 186        return 0;
 187}
 188
 189static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
 190                                u8 *out)
 191{
 192        if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) {
 193                kernel_fpu_begin();
 194                *(__le32 *)out = ~cpu_to_le32(crc_pcl(data, len, *crcp));
 195                kernel_fpu_end();
 196        } else
 197                *(__le32 *)out =
 198                        ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
 199        return 0;
 200}
 201
 202static int crc32c_pcl_intel_finup(struct shash_desc *desc, const u8 *data,
 203                              unsigned int len, u8 *out)
 204{
 205        return __crc32c_pcl_intel_finup(shash_desc_ctx(desc), data, len, out);
 206}
 207
 208static int crc32c_pcl_intel_digest(struct shash_desc *desc, const u8 *data,
 209                               unsigned int len, u8 *out)
 210{
 211        return __crc32c_pcl_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
 212                                    out);
 213}
 214#endif /* CONFIG_X86_64 */
 215
 216static struct shash_alg alg = {
 217        .setkey                 =       crc32c_intel_setkey,
 218        .init                   =       crc32c_intel_init,
 219        .update                 =       crc32c_intel_update,
 220        .final                  =       crc32c_intel_final,
 221        .finup                  =       crc32c_intel_finup,
 222        .digest                 =       crc32c_intel_digest,
 223        .descsize               =       sizeof(u32),
 224        .digestsize             =       CHKSUM_DIGEST_SIZE,
 225        .base                   =       {
 226                .cra_name               =       "crc32c",
 227                .cra_driver_name        =       "crc32c-intel",
 228                .cra_priority           =       200,
 229                .cra_blocksize          =       CHKSUM_BLOCK_SIZE,
 230                .cra_ctxsize            =       sizeof(u32),
 231                .cra_module             =       THIS_MODULE,
 232                .cra_init               =       crc32c_intel_cra_init,
 233        }
 234};
 235
 236static const struct x86_cpu_id crc32c_cpu_id[] = {
 237        X86_FEATURE_MATCH(X86_FEATURE_XMM4_2),
 238        {}
 239};
 240MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
 241
 242static int __init crc32c_intel_mod_init(void)
 243{
 244        if (!x86_match_cpu(crc32c_cpu_id))
 245                return -ENODEV;
 246#ifdef CONFIG_X86_64
 247        if (boot_cpu_has(X86_FEATURE_PCLMULQDQ)) {
 248                alg.update = crc32c_pcl_intel_update;
 249                alg.finup = crc32c_pcl_intel_finup;
 250                alg.digest = crc32c_pcl_intel_digest;
 251        }
 252#endif
 253        return crypto_register_shash(&alg);
 254}
 255
 256static void __exit crc32c_intel_mod_fini(void)
 257{
 258        crypto_unregister_shash(&alg);
 259}
 260
 261module_init(crc32c_intel_mod_init);
 262module_exit(crc32c_intel_mod_fini);
 263
 264MODULE_AUTHOR("Austin Zhang <austin.zhang@intel.com>, Kent Liu <kent.liu@intel.com>");
 265MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
 266MODULE_LICENSE("GPL");
 267
 268MODULE_ALIAS_CRYPTO("crc32c");
 269MODULE_ALIAS_CRYPTO("crc32c-intel");
 270