1 #include <linux/kernel.h> 2 #include <linux/module.h> 3 #include <linux/list.h> 4 #include <linux/random.h> 5 #include <linux/string.h> 6 #include <linux/bitops.h> 7 #include <linux/slab.h> 8 #include <linux/mtd/nand_ecc.h> 9 10 /* 11 * Test the implementation for software ECC 12 * 13 * No actual MTD device is needed, So we don't need to warry about losing 14 * important data by human error. 15 * 16 * This covers possible patterns of corruption which can be reliably corrected 17 * or detected. 18 */ 19 20 #if defined(CONFIG_MTD_NAND) || defined(CONFIG_MTD_NAND_MODULE) 21 22 struct nand_ecc_test { 23 const char *name; 24 void (*prepare)(void *, void *, void *, void *, const size_t); 25 int (*verify)(void *, void *, void *, const size_t); 26 }; 27 28 /* 29 * The reason for this __change_bit_le() instead of __change_bit() is to inject 30 * bit error properly within the region which is not a multiple of 31 * sizeof(unsigned long) on big-endian systems 32 */ 33 #ifdef __LITTLE_ENDIAN 34 #define __change_bit_le(nr, addr) __change_bit(nr, addr) 35 #elif defined(__BIG_ENDIAN) 36 #define __change_bit_le(nr, addr) \ 37 __change_bit((nr) ^ ((BITS_PER_LONG - 1) & ~0x7), addr) 38 #else 39 #error "Unknown byte order" 40 #endif 41 42 static void single_bit_error_data(void *error_data, void *correct_data, 43 size_t size) 44 { 45 unsigned int offset = random32() % (size * BITS_PER_BYTE); 46 47 memcpy(error_data, correct_data, size); 48 __change_bit_le(offset, error_data); 49 } 50 51 static void double_bit_error_data(void *error_data, void *correct_data, 52 size_t size) 53 { 54 unsigned int offset[2]; 55 56 offset[0] = random32() % (size * BITS_PER_BYTE); 57 do { 58 offset[1] = random32() % (size * BITS_PER_BYTE); 59 } while (offset[0] == offset[1]); 60 61 memcpy(error_data, correct_data, size); 62 63 __change_bit_le(offset[0], error_data); 64 __change_bit_le(offset[1], error_data); 65 } 66 67 static unsigned int random_ecc_bit(size_t size) 68 { 69 unsigned int offset = random32() % (3 * BITS_PER_BYTE); 70 71 if (size == 256) { 72 /* 73 * Don't inject a bit error into the insignificant bits (16th 74 * and 17th bit) in ECC code for 256 byte data block 75 */ 76 while (offset == 16 || offset == 17) 77 offset = random32() % (3 * BITS_PER_BYTE); 78 } 79 80 return offset; 81 } 82 83 static void single_bit_error_ecc(void *error_ecc, void *correct_ecc, 84 size_t size) 85 { 86 unsigned int offset = random_ecc_bit(size); 87 88 memcpy(error_ecc, correct_ecc, 3); 89 __change_bit_le(offset, error_ecc); 90 } 91 92 static void double_bit_error_ecc(void *error_ecc, void *correct_ecc, 93 size_t size) 94 { 95 unsigned int offset[2]; 96 97 offset[0] = random_ecc_bit(size); 98 do { 99 offset[1] = random_ecc_bit(size); 100 } while (offset[0] == offset[1]); 101 102 memcpy(error_ecc, correct_ecc, 3); 103 __change_bit_le(offset[0], error_ecc); 104 __change_bit_le(offset[1], error_ecc); 105 } 106 107 static void no_bit_error(void *error_data, void *error_ecc, 108 void *correct_data, void *correct_ecc, const size_t size) 109 { 110 memcpy(error_data, correct_data, size); 111 memcpy(error_ecc, correct_ecc, 3); 112 } 113 114 static int no_bit_error_verify(void *error_data, void *error_ecc, 115 void *correct_data, const size_t size) 116 { 117 unsigned char calc_ecc[3]; 118 int ret; 119 120 __nand_calculate_ecc(error_data, size, calc_ecc); 121 ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size); 122 if (ret == 0 && !memcmp(correct_data, error_data, size)) 123 return 0; 124 125 return -EINVAL; 126 } 127 128 static void single_bit_error_in_data(void *error_data, void *error_ecc, 129 void *correct_data, void *correct_ecc, const size_t size) 130 { 131 single_bit_error_data(error_data, correct_data, size); 132 memcpy(error_ecc, correct_ecc, 3); 133 } 134 135 static void single_bit_error_in_ecc(void *error_data, void *error_ecc, 136 void *correct_data, void *correct_ecc, const size_t size) 137 { 138 memcpy(error_data, correct_data, size); 139 single_bit_error_ecc(error_ecc, correct_ecc, size); 140 } 141 142 static int single_bit_error_correct(void *error_data, void *error_ecc, 143 void *correct_data, const size_t size) 144 { 145 unsigned char calc_ecc[3]; 146 int ret; 147 148 __nand_calculate_ecc(error_data, size, calc_ecc); 149 ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size); 150 if (ret == 1 && !memcmp(correct_data, error_data, size)) 151 return 0; 152 153 return -EINVAL; 154 } 155 156 static void double_bit_error_in_data(void *error_data, void *error_ecc, 157 void *correct_data, void *correct_ecc, const size_t size) 158 { 159 double_bit_error_data(error_data, correct_data, size); 160 memcpy(error_ecc, correct_ecc, 3); 161 } 162 163 static void single_bit_error_in_data_and_ecc(void *error_data, void *error_ecc, 164 void *correct_data, void *correct_ecc, const size_t size) 165 { 166 single_bit_error_data(error_data, correct_data, size); 167 single_bit_error_ecc(error_ecc, correct_ecc, size); 168 } 169 170 static void double_bit_error_in_ecc(void *error_data, void *error_ecc, 171 void *correct_data, void *correct_ecc, const size_t size) 172 { 173 memcpy(error_data, correct_data, size); 174 double_bit_error_ecc(error_ecc, correct_ecc, size); 175 } 176 177 static int double_bit_error_detect(void *error_data, void *error_ecc, 178 void *correct_data, const size_t size) 179 { 180 unsigned char calc_ecc[3]; 181 int ret; 182 183 __nand_calculate_ecc(error_data, size, calc_ecc); 184 ret = __nand_correct_data(error_data, error_ecc, calc_ecc, size); 185 186 return (ret == -1) ? 0 : -EINVAL; 187 } 188 189 static const struct nand_ecc_test nand_ecc_test[] = { 190 { 191 .name = "no-bit-error", 192 .prepare = no_bit_error, 193 .verify = no_bit_error_verify, 194 }, 195 { 196 .name = "single-bit-error-in-data-correct", 197 .prepare = single_bit_error_in_data, 198 .verify = single_bit_error_correct, 199 }, 200 { 201 .name = "single-bit-error-in-ecc-correct", 202 .prepare = single_bit_error_in_ecc, 203 .verify = single_bit_error_correct, 204 }, 205 { 206 .name = "double-bit-error-in-data-detect", 207 .prepare = double_bit_error_in_data, 208 .verify = double_bit_error_detect, 209 }, 210 { 211 .name = "single-bit-error-in-data-and-ecc-detect", 212 .prepare = single_bit_error_in_data_and_ecc, 213 .verify = double_bit_error_detect, 214 }, 215 { 216 .name = "double-bit-error-in-ecc-detect", 217 .prepare = double_bit_error_in_ecc, 218 .verify = double_bit_error_detect, 219 }, 220 }; 221 222 static void dump_data_ecc(void *error_data, void *error_ecc, void *correct_data, 223 void *correct_ecc, const size_t size) 224 { 225 pr_info("hexdump of error data:\n"); 226 print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4, 227 error_data, size, false); 228 print_hex_dump(KERN_INFO, "hexdump of error ecc: ", 229 DUMP_PREFIX_NONE, 16, 1, error_ecc, 3, false); 230 231 pr_info("hexdump of correct data:\n"); 232 print_hex_dump(KERN_INFO, "", DUMP_PREFIX_OFFSET, 16, 4, 233 correct_data, size, false); 234 print_hex_dump(KERN_INFO, "hexdump of correct ecc: ", 235 DUMP_PREFIX_NONE, 16, 1, correct_ecc, 3, false); 236 } 237 238 static int nand_ecc_test_run(const size_t size) 239 { 240 int i; 241 int err = 0; 242 void *error_data; 243 void *error_ecc; 244 void *correct_data; 245 void *correct_ecc; 246 247 error_data = kmalloc(size, GFP_KERNEL); 248 error_ecc = kmalloc(3, GFP_KERNEL); 249 correct_data = kmalloc(size, GFP_KERNEL); 250 correct_ecc = kmalloc(3, GFP_KERNEL); 251 252 if (!error_data || !error_ecc || !correct_data || !correct_ecc) { 253 err = -ENOMEM; 254 goto error; 255 } 256 257 get_random_bytes(correct_data, size); 258 __nand_calculate_ecc(correct_data, size, correct_ecc); 259 260 for (i = 0; i < ARRAY_SIZE(nand_ecc_test); i++) { 261 nand_ecc_test[i].prepare(error_data, error_ecc, 262 correct_data, correct_ecc, size); 263 err = nand_ecc_test[i].verify(error_data, error_ecc, 264 correct_data, size); 265 266 if (err) { 267 pr_err("mtd_nandecctest: not ok - %s-%zd\n", 268 nand_ecc_test[i].name, size); 269 dump_data_ecc(error_data, error_ecc, 270 correct_data, correct_ecc, size); 271 break; 272 } 273 pr_info("mtd_nandecctest: ok - %s-%zd\n", 274 nand_ecc_test[i].name, size); 275 } 276 error: 277 kfree(error_data); 278 kfree(error_ecc); 279 kfree(correct_data); 280 kfree(correct_ecc); 281 282 return err; 283 } 284 285 #else 286 287 static int nand_ecc_test_run(const size_t size) 288 { 289 return 0; 290 } 291 292 #endif 293 294 static int __init ecc_test_init(void) 295 { 296 int err; 297 298 err = nand_ecc_test_run(256); 299 if (err) 300 return err; 301 302 return nand_ecc_test_run(512); 303 } 304 305 static void __exit ecc_test_exit(void) 306 { 307 } 308 309 module_init(ecc_test_init); 310 module_exit(ecc_test_exit); 311 312 MODULE_DESCRIPTION("NAND ECC function test module"); 313 MODULE_AUTHOR("Akinobu Mita"); 314 MODULE_LICENSE("GPL"); 315