drivers/mtd/tests/mtd_nandecctest.c

   1 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
   2
   3 #include <linux/kernel.h>
   4 #include <linux/module.h>
   5 #include <linux/list.h>
   6 #include <linux/random.h>
   7 #include <linux/string.h>
   8 #include <linux/bitops.h>
   9 #include <linux/slab.h>
  10 #include <linux/mtd/nand_ecc.h>
  11
  12 /*
  13  * Test the implementation for software ECC
  14  *
  15  * No actual MTD device is needed, So we don't need to warry about losing
  16  * important data by human error.
  17  *
  18  * This covers possible patterns of corruption which can be reliably corrected
  19  * or detected.
  20  */
  21
  22 #if IS_ENABLED(CONFIG_MTD_NAND)
  23
  24 struct nand_ecc_test {
  25         const char *name;
  26         void (*prepare)(void *, void *, void *, void *, const size_t);
  27         int (*verify)(void *, void *, void *, const size_t);
  28 };
  29
  30 /*
  31  * The reason for this __change_bit_le() instead of __change_bit() is to inject
  32  * bit error properly within the region which is not a multiple of
  33  * sizeof(unsigned long) on big-endian systems
  34  */
  35 #ifdef __LITTLE_ENDIAN
  36 #define __change_bit_le(nr, addr) __change_bit(nr, addr)
  37 #elif defined(__BIG_ENDIAN)
  38 #define __change_bit_le(nr, addr) \
  39                 __change_bit((nr) ^ ((BITS_PER_LONG - 1) & ~0x7), addr)
  40 #else
  41 #error "Unknown byte order"
  42 #endif
  43
  44 static void single_bit_error_data(void *error_data, void *correct_data,
  45                                 size_t size)
  46 {
  47         unsigned int offset = prandom_u32() % (size * BITS_PER_BYTE);
  48
  49         memcpy(error_data, correct_data, size);
  50         __change_bit_le(offset, error_data);
  51 }
  52
  53 static void double_bit_error_data(void *error_data, void *correct_data,
  54                                 size_t size)
  55 {
  56         unsigned int offset[2];
  57
  58         offset[0] = prandom_u32() % (size * BITS_PER_BYTE);
  59         do {
  60                 offset[1] = prandom_u32() % (size * BITS_PER_BYTE);
  61         } while (offset[0] == offset[1]);
  62
  63         memcpy(error_data, correct_data, size);
  64
  65         __change_bit_le(offset[0], error_data);
  66         __change_bit_le(offset[1], error_data);
  67 }
  68
  69 static unsigned int random_ecc_bit(size_t size)
  70 {
  71         unsigned int offset = prandom_u32() % (3 * BITS_PER_BYTE);
  72
  73         if (size == 256) {
  74                 /*
  75                  * Don't inject a bit error into the insignificant bits (16th
  76                  * and 17th bit) in ECC code for 256 byte data block
  77                  */
  78                 while (offset == 16 || offset == 17)
  79                         offset = prandom_u32() % (3 * BITS_PER_BYTE);
  80         }
  81
  82         return offset;
  83 }
  84
  85 static void single_bit_error_ecc(void *error_ecc, void *correct_ecc,
  86                                 size_t size)
  87 {
  88         unsigned int offset = random_ecc_bit(size);
  89
  90         memcpy(error_ecc, correct_ecc, 3);
  91         __change_bit_le(offset, error_ecc);
  92 }
  93
  94 static void double_bit_error_ecc(void *error_ecc, void *correct_ecc,
  95                                 size_t size)
  96 {
  97         unsigned int offset[2];
  98
  99         offset[0] = random_ecc_bit(size);
 100         do {
 101                 offset[1] = random_ecc_bit(size);
 102         } while (offset[0] == offset[1]);
 103
 104         memcpy(error_ecc, correct_ecc, 3);
 105         __change_bit_le(offset[0], error_ecc);
 106         __change_bit_le(offset[1], error_ecc);
 107 }
 108
 109 static void no_bit_error(void *error_data, void *error_ecc,
 110                 void *correct_data, void *correct_ecc, const size_t size)
 111 {
 112         memcpy(error_data, correct_data, size);
 113         memcpy(error_ecc, correct_ecc, 3);
 114 }
 115
 116 static int no_bit_error_verify(void *error_data, void *error_ecc,
 117                                 void *correct_data, const size_t size)
 118 {
 119         unsigned char calc_ecc[3];
 120         int ret;
 121
 122         __nand_calculate_ecc(error_data, size, calc_ecc);
 123         ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
 124         if (ret == 0 && !memcmp(correct_data, error_data, size))
 125                 return 0;
 126
 127         return -EINVAL;
 128 }
 129
 130 static void single_bit_error_in_data(void *error_data, void *error_ecc,
 131                 void *correct_data, void *correct_ecc, const size_t size)
 132 {
 133         single_bit_error_data(error_data, correct_data, size);
 134         memcpy(error_ecc, correct_ecc, 3);
 135 }
 136
 137 static void single_bit_error_in_ecc(void *error_data, void *error_ecc,
 138                 void *correct_data, void *correct_ecc, const size_t size)
 139 {
 140         memcpy(error_data, correct_data, size);
 141         single_bit_error_ecc(error_ecc, correct_ecc, size);
 142 }
 143
 144 static int single_bit_error_correct(void *error_data, void *error_ecc,
 145                                 void *correct_data, const size_t size)
 146 {
 147         unsigned char calc_ecc[3];
 148         int ret;
 149
 150         __nand_calculate_ecc(error_data, size, calc_ecc);
 151         ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
 152         if (ret == 1 && !memcmp(correct_data, error_data, size))
 153                 return 0;
 154
 155         return -EINVAL;
 156 }
 157
 158 static void double_bit_error_in_data(void *error_data, void *error_ecc,
 159                 void *correct_data, void *correct_ecc, const size_t size)
 160 {
 161         double_bit_error_data(error_data, correct_data, size);
 162         memcpy(error_ecc, correct_ecc, 3);
 163 }
 164
 165 static void single_bit_error_in_data_and_ecc(void *error_data, void *error_ecc,
 166                 void *correct_data, void *correct_ecc, const size_t size)
 167 {
 168         single_bit_error_data(error_data, correct_data, size);
 169         single_bit_error_ecc(error_ecc, correct_ecc, size);
 170 }
 171
 172 static void double_bit_error_in_ecc(void *error_data, void *error_ecc,
 173                 void *correct_data, void *correct_ecc, const size_t size)
 174 {
 175         memcpy(error_data, correct_data, size);
 176         double_bit_error_ecc(error_ecc, correct_ecc, size);
 177 }
 178
 179 static int double_bit_error_detect(void *error_data, void *error_ecc,
 180                                 void *correct_data, const size_t size)
 181 {
 182         unsigned char calc_ecc[3];
 183         int ret;
 184
 185         __nand_calculate_ecc(error_data, size, calc_ecc);
 186         ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
 187
 188         return (ret == -1) ? 0 : -EINVAL;
 189 }
 190
 191 static const struct nand_ecc_test nand_ecc_test[] = {
 192         {
 193                 .name = "no-bit-error",
 194                 .prepare = no_bit_error,
 195                 .verify = no_bit_error_verify,
 196         },
 197         {
 198                 .name = "single-bit-error-in-data-correct",
 199                 .prepare = single_bit_error_in_data,
 200                 .verify = single_bit_error_correct,
 201         },
 202         {
 203                 .name = "single-bit-error-in-ecc-correct",
 204                 .prepare = single_bit_error_in_ecc,
 205                 .verify = single_bit_error_correct,
 206         },
 207         {
 208                 .name = "double-bit-error-in-data-detect",
 209                 .prepare = double_bit_error_in_data,
 210                 .verify = double_bit_error_detect,
 211         },
 212         {
 213                 .name = "single-bit-error-in-data-and-ecc-detect",
 214                 .prepare = single_bit_error_in_data_and_ecc,
 215                 .verify = double_bit_error_detect,
 216         },
 217         {
 218                 .name = "double-bit-error-in-ecc-detect",
 219                 .prepare = double_bit_error_in_ecc,
 220                 .verify = double_bit_error_detect,
 221         },
 222 };
 223
 224 static void dump_data_ecc(void *error_data, void *error_ecc, void *correct_data,
 225                         void *correct_ecc, const size_t size)
 226 {
 227         pr_info("hexdump of error data:\n");
 228         print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
 229                         error_data, size, false);
 230         print_hex_dump(KERN_INFO, "hexdump of error ecc: ",
 231                         DUMP_PREFIX_NONE, 16, 1, error_ecc, 3, false);
 232
 233         pr_info("hexdump of correct data:\n");
 234         print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
 235                         correct_data, size, false);
 236         print_hex_dump(KERN_INFO, "hexdump of correct ecc: ",
 237                         DUMP_PREFIX_NONE, 16, 1, correct_ecc, 3, false);
 238 }
 239
 240 static int nand_ecc_test_run(const size_t size)
 241 {
 242         int i;
 243         int err = 0;
 244         void *error_data;
 245         void *error_ecc;
 246         void *correct_data;
 247         void *correct_ecc;
 248
 249         error_data = kmalloc(size, GFP_KERNEL);
 250         error_ecc = kmalloc(3, GFP_KERNEL);
 251         correct_data = kmalloc(size, GFP_KERNEL);
 252         correct_ecc = kmalloc(3, GFP_KERNEL);
 253
 254         if (!error_data || !error_ecc || !correct_data || !correct_ecc) {
 255                 err = -ENOMEM;
 256                 goto error;
 257         }
 258
 259         prandom_bytes(correct_data, size);
 260         __nand_calculate_ecc(correct_data, size, correct_ecc);
 261
 262         for (i = 0; i < ARRAY_SIZE(nand_ecc_test); i++) {
 263                 nand_ecc_test[i].prepare(error_data, error_ecc,
 264                                 correct_data, correct_ecc, size);
 265                 err = nand_ecc_test[i].verify(error_data, error_ecc,
 266                                                 correct_data, size);
 267
 268                 if (err) {
 269                         pr_err("not ok - %s-%zd\n",
 270                                 nand_ecc_test[i].name, size);
 271                         dump_data_ecc(error_data, error_ecc,
 272                                 correct_data, correct_ecc, size);
 273                         break;
 274                 }
 275                 pr_info("ok - %s-%zd\n",
 276                         nand_ecc_test[i].name, size);
 277         }
 278 error:
 279         kfree(error_data);
 280         kfree(error_ecc);
 281         kfree(correct_data);
 282         kfree(correct_ecc);
 283
 284         return err;
 285 }
 286
 287 #else
 288
 289 static int nand_ecc_test_run(const size_t size)
 290 {
 291         return 0;
 292 }
 293
 294 #endif
 295
 296 static int __init ecc_test_init(void)
 297 {
 298         int err;
 299
 300         err = nand_ecc_test_run(256);
 301         if (err)
 302                 return err;
 303
 304         return nand_ecc_test_run(512);
 305 }
 306
 307 static void __exit ecc_test_exit(void)
 308 {
 309 }
 310
 311 module_init(ecc_test_init);
 312 module_exit(ecc_test_exit);
 313
 314 MODULE_DESCRIPTION("NAND ECC function test module");
 315 MODULE_AUTHOR("Akinobu Mita");
 316 MODULE_LICENSE("GPL");