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 #include "mtd_test.h"
  13
  14 /*
  15  * Test the implementation for software ECC
  16  *
  17  * No actual MTD device is needed, So we don't need to warry about losing
  18  * important data by human error.
  19  *
  20  * This covers possible patterns of corruption which can be reliably corrected
  21  * or detected.
  22  */
  23
  24 #if IS_ENABLED(CONFIG_MTD_NAND)
  25
  26 struct nand_ecc_test {
  27         const char *name;
  28         void (*prepare)(void *, void *, void *, void *, const size_t);
  29         int (*verify)(void *, void *, void *, const size_t);
  30 };
  31
  32 /*
  33  * The reason for this __change_bit_le() instead of __change_bit() is to inject
  34  * bit error properly within the region which is not a multiple of
  35  * sizeof(unsigned long) on big-endian systems
  36  */
  37 #ifdef __LITTLE_ENDIAN
  38 #define __change_bit_le(nr, addr) __change_bit(nr, addr)
  39 #elif defined(__BIG_ENDIAN)
  40 #define __change_bit_le(nr, addr) \
  41                 __change_bit((nr) ^ ((BITS_PER_LONG - 1) & ~0x7), addr)
  42 #else
  43 #error "Unknown byte order"
  44 #endif
  45
  46 static void single_bit_error_data(void *error_data, void *correct_data,
  47                                 size_t size)
  48 {
  49         unsigned int offset = prandom_u32() % (size * BITS_PER_BYTE);
  50
  51         memcpy(error_data, correct_data, size);
  52         __change_bit_le(offset, error_data);
  53 }
  54
  55 static void double_bit_error_data(void *error_data, void *correct_data,
  56                                 size_t size)
  57 {
  58         unsigned int offset[2];
  59
  60         offset[0] = prandom_u32() % (size * BITS_PER_BYTE);
  61         do {
  62                 offset[1] = prandom_u32() % (size * BITS_PER_BYTE);
  63         } while (offset[0] == offset[1]);
  64
  65         memcpy(error_data, correct_data, size);
  66
  67         __change_bit_le(offset[0], error_data);
  68         __change_bit_le(offset[1], error_data);
  69 }
  70
  71 static unsigned int random_ecc_bit(size_t size)
  72 {
  73         unsigned int offset = prandom_u32() % (3 * BITS_PER_BYTE);
  74
  75         if (size == 256) {
  76                 /*
  77                  * Don't inject a bit error into the insignificant bits (16th
  78                  * and 17th bit) in ECC code for 256 byte data block
  79                  */
  80                 while (offset == 16 || offset == 17)
  81                         offset = prandom_u32() % (3 * BITS_PER_BYTE);
  82         }
  83
  84         return offset;
  85 }
  86
  87 static void single_bit_error_ecc(void *error_ecc, void *correct_ecc,
  88                                 size_t size)
  89 {
  90         unsigned int offset = random_ecc_bit(size);
  91
  92         memcpy(error_ecc, correct_ecc, 3);
  93         __change_bit_le(offset, error_ecc);
  94 }
  95
  96 static void double_bit_error_ecc(void *error_ecc, void *correct_ecc,
  97                                 size_t size)
  98 {
  99         unsigned int offset[2];
 100
 101         offset[0] = random_ecc_bit(size);
 102         do {
 103                 offset[1] = random_ecc_bit(size);
 104         } while (offset[0] == offset[1]);
 105
 106         memcpy(error_ecc, correct_ecc, 3);
 107         __change_bit_le(offset[0], error_ecc);
 108         __change_bit_le(offset[1], error_ecc);
 109 }
 110
 111 static void no_bit_error(void *error_data, void *error_ecc,
 112                 void *correct_data, void *correct_ecc, const size_t size)
 113 {
 114         memcpy(error_data, correct_data, size);
 115         memcpy(error_ecc, correct_ecc, 3);
 116 }
 117
 118 static int no_bit_error_verify(void *error_data, void *error_ecc,
 119                                 void *correct_data, const size_t size)
 120 {
 121         unsigned char calc_ecc[3];
 122         int ret;
 123
 124         __nand_calculate_ecc(error_data, size, calc_ecc);
 125         ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
 126         if (ret == 0 && !memcmp(correct_data, error_data, size))
 127                 return 0;
 128
 129         return -EINVAL;
 130 }
 131
 132 static void single_bit_error_in_data(void *error_data, void *error_ecc,
 133                 void *correct_data, void *correct_ecc, const size_t size)
 134 {
 135         single_bit_error_data(error_data, correct_data, size);
 136         memcpy(error_ecc, correct_ecc, 3);
 137 }
 138
 139 static void single_bit_error_in_ecc(void *error_data, void *error_ecc,
 140                 void *correct_data, void *correct_ecc, const size_t size)
 141 {
 142         memcpy(error_data, correct_data, size);
 143         single_bit_error_ecc(error_ecc, correct_ecc, size);
 144 }
 145
 146 static int single_bit_error_correct(void *error_data, void *error_ecc,
 147                                 void *correct_data, const size_t size)
 148 {
 149         unsigned char calc_ecc[3];
 150         int ret;
 151
 152         __nand_calculate_ecc(error_data, size, calc_ecc);
 153         ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
 154         if (ret == 1 && !memcmp(correct_data, error_data, size))
 155                 return 0;
 156
 157         return -EINVAL;
 158 }
 159
 160 static void double_bit_error_in_data(void *error_data, void *error_ecc,
 161                 void *correct_data, void *correct_ecc, const size_t size)
 162 {
 163         double_bit_error_data(error_data, correct_data, size);
 164         memcpy(error_ecc, correct_ecc, 3);
 165 }
 166
 167 static void single_bit_error_in_data_and_ecc(void *error_data, void *error_ecc,
 168                 void *correct_data, void *correct_ecc, const size_t size)
 169 {
 170         single_bit_error_data(error_data, correct_data, size);
 171         single_bit_error_ecc(error_ecc, correct_ecc, size);
 172 }
 173
 174 static void double_bit_error_in_ecc(void *error_data, void *error_ecc,
 175                 void *correct_data, void *correct_ecc, const size_t size)
 176 {
 177         memcpy(error_data, correct_data, size);
 178         double_bit_error_ecc(error_ecc, correct_ecc, size);
 179 }
 180
 181 static int double_bit_error_detect(void *error_data, void *error_ecc,
 182                                 void *correct_data, const size_t size)
 183 {
 184         unsigned char calc_ecc[3];
 185         int ret;
 186
 187         __nand_calculate_ecc(error_data, size, calc_ecc);
 188         ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size);
 189
 190         return (ret == -EBADMSG) ? 0 : -EINVAL;
 191 }
 192
 193 static const struct nand_ecc_test nand_ecc_test[] = {
 194         {
 195                 .name = "no-bit-error",
 196                 .prepare = no_bit_error,
 197                 .verify = no_bit_error_verify,
 198         },
 199         {
 200                 .name = "single-bit-error-in-data-correct",
 201                 .prepare = single_bit_error_in_data,
 202                 .verify = single_bit_error_correct,
 203         },
 204         {
 205                 .name = "single-bit-error-in-ecc-correct",
 206                 .prepare = single_bit_error_in_ecc,
 207                 .verify = single_bit_error_correct,
 208         },
 209         {
 210                 .name = "double-bit-error-in-data-detect",
 211                 .prepare = double_bit_error_in_data,
 212                 .verify = double_bit_error_detect,
 213         },
 214         {
 215                 .name = "single-bit-error-in-data-and-ecc-detect",
 216                 .prepare = single_bit_error_in_data_and_ecc,
 217                 .verify = double_bit_error_detect,
 218         },
 219         {
 220                 .name = "double-bit-error-in-ecc-detect",
 221                 .prepare = double_bit_error_in_ecc,
 222                 .verify = double_bit_error_detect,
 223         },
 224 };
 225
 226 static void dump_data_ecc(void *error_data, void *error_ecc, void *correct_data,
 227                         void *correct_ecc, const size_t size)
 228 {
 229         pr_info("hexdump of error data:\n");
 230         print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
 231                         error_data, size, false);
 232         print_hex_dump(KERN_INFO, "hexdump of error ecc: ",
 233                         DUMP_PREFIX_NONE, 16, 1, error_ecc, 3, false);
 234
 235         pr_info("hexdump of correct data:\n");
 236         print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4,
 237                         correct_data, size, false);
 238         print_hex_dump(KERN_INFO, "hexdump of correct ecc: ",
 239                         DUMP_PREFIX_NONE, 16, 1, correct_ecc, 3, false);
 240 }
 241
 242 static int nand_ecc_test_run(const size_t size)
 243 {
 244         int i;
 245         int err = 0;
 246         void *error_data;
 247         void *error_ecc;
 248         void *correct_data;
 249         void *correct_ecc;
 250
 251         error_data = kmalloc(size, GFP_KERNEL);
 252         error_ecc = kmalloc(3, GFP_KERNEL);
 253         correct_data = kmalloc(size, GFP_KERNEL);
 254         correct_ecc = kmalloc(3, GFP_KERNEL);
 255
 256         if (!error_data || !error_ecc || !correct_data || !correct_ecc) {
 257                 err = -ENOMEM;
 258                 goto error;
 259         }
 260
 261         prandom_bytes(correct_data, size);
 262         __nand_calculate_ecc(correct_data, size, correct_ecc);
 263
 264         for (i = 0; i < ARRAY_SIZE(nand_ecc_test); i++) {
 265                 nand_ecc_test[i].prepare(error_data, error_ecc,
 266                                 correct_data, correct_ecc, size);
 267                 err = nand_ecc_test[i].verify(error_data, error_ecc,
 268                                                 correct_data, size);
 269
 270                 if (err) {
 271                         pr_err("not ok - %s-%zd\n",
 272                                 nand_ecc_test[i].name, size);
 273                         dump_data_ecc(error_data, error_ecc,
 274                                 correct_data, correct_ecc, size);
 275                         break;
 276                 }
 277                 pr_info("ok - %s-%zd\n",
 278                         nand_ecc_test[i].name, size);
 279
 280                 err = mtdtest_relax();
 281                 if (err)
 282                         break;
 283         }
 284 error:
 285         kfree(error_data);
 286         kfree(error_ecc);
 287         kfree(correct_data);
 288         kfree(correct_ecc);
 289
 290         return err;
 291 }
 292
 293 #else
 294
 295 static int nand_ecc_test_run(const size_t size)
 296 {
 297         return 0;
 298 }
 299
 300 #endif
 301
 302 static int __init ecc_test_init(void)
 303 {
 304         int err;
 305
 306         err = nand_ecc_test_run(256);
 307         if (err)
 308                 return err;
 309
 310         return nand_ecc_test_run(512);
 311 }
 312
 313 static void __exit ecc_test_exit(void)
 314 {
 315 }
 316
 317 module_init(ecc_test_init);
 318 module_exit(ecc_test_exit);
 319
 320 MODULE_DESCRIPTION("NAND ECC function test module");
 321 MODULE_AUTHOR("Akinobu Mita");
 322 MODULE_LICENSE("GPL");