1 /* 2 * Copyright (C) 2012 Google, Inc. 3 * 4 * This software is licensed under the terms of the GNU General Public 5 * License version 2, as published by the Free Software Foundation, and 6 * may be copied, distributed, and modified under those terms. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 * 13 */ 14 15 #include <linux/device.h> 16 #include <linux/err.h> 17 #include <linux/errno.h> 18 #include <linux/kernel.h> 19 #include <linux/init.h> 20 #include <linux/io.h> 21 #include <linux/list.h> 22 #include <linux/memblock.h> 23 #include <linux/rslib.h> 24 #include <linux/slab.h> 25 #include <linux/vmalloc.h> 26 #include <linux/pstore_ram.h> 27 #include <asm/page.h> 28 29 struct persistent_ram_buffer { 30 uint32_t sig; 31 atomic_t start; 32 atomic_t size; 33 uint8_t data[0]; 34 }; 35 36 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */ 37 38 static inline size_t buffer_size(struct persistent_ram_zone *prz) 39 { 40 return atomic_read(&prz->buffer->size); 41 } 42 43 static inline size_t buffer_start(struct persistent_ram_zone *prz) 44 { 45 return atomic_read(&prz->buffer->start); 46 } 47 48 /* increase and wrap the start pointer, returning the old value */ 49 static inline size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a) 50 { 51 int old; 52 int new; 53 54 do { 55 old = atomic_read(&prz->buffer->start); 56 new = old + a; 57 while (unlikely(new > prz->buffer_size)) 58 new -= prz->buffer_size; 59 } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old); 60 61 return old; 62 } 63 64 /* increase the size counter until it hits the max size */ 65 static inline void buffer_size_add(struct persistent_ram_zone *prz, size_t a) 66 { 67 size_t old; 68 size_t new; 69 70 if (atomic_read(&prz->buffer->size) == prz->buffer_size) 71 return; 72 73 do { 74 old = atomic_read(&prz->buffer->size); 75 new = old + a; 76 if (new > prz->buffer_size) 77 new = prz->buffer_size; 78 } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); 79 } 80 81 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, 82 uint8_t *data, size_t len, uint8_t *ecc) 83 { 84 int i; 85 uint16_t par[prz->ecc_info.ecc_size]; 86 87 /* Initialize the parity buffer */ 88 memset(par, 0, sizeof(par)); 89 encode_rs8(prz->rs_decoder, data, len, par, 0); 90 for (i = 0; i < prz->ecc_info.ecc_size; i++) 91 ecc[i] = par[i]; 92 } 93 94 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz, 95 void *data, size_t len, uint8_t *ecc) 96 { 97 int i; 98 uint16_t par[prz->ecc_info.ecc_size]; 99 100 for (i = 0; i < prz->ecc_info.ecc_size; i++) 101 par[i] = ecc[i]; 102 return decode_rs8(prz->rs_decoder, data, par, len, 103 NULL, 0, NULL, 0, NULL); 104 } 105 106 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz, 107 unsigned int start, unsigned int count) 108 { 109 struct persistent_ram_buffer *buffer = prz->buffer; 110 uint8_t *buffer_end = buffer->data + prz->buffer_size; 111 uint8_t *block; 112 uint8_t *par; 113 int ecc_block_size = prz->ecc_info.block_size; 114 int ecc_size = prz->ecc_info.ecc_size; 115 int size = ecc_block_size; 116 117 if (!ecc_size) 118 return; 119 120 block = buffer->data + (start & ~(ecc_block_size - 1)); 121 par = prz->par_buffer + (start / ecc_block_size) * ecc_size; 122 123 do { 124 if (block + ecc_block_size > buffer_end) 125 size = buffer_end - block; 126 persistent_ram_encode_rs8(prz, block, size, par); 127 block += ecc_block_size; 128 par += ecc_size; 129 } while (block < buffer->data + start + count); 130 } 131 132 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz) 133 { 134 struct persistent_ram_buffer *buffer = prz->buffer; 135 136 if (!prz->ecc_info.ecc_size) 137 return; 138 139 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer), 140 prz->par_header); 141 } 142 143 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz) 144 { 145 struct persistent_ram_buffer *buffer = prz->buffer; 146 uint8_t *block; 147 uint8_t *par; 148 149 if (!prz->ecc_info.ecc_size) 150 return; 151 152 block = buffer->data; 153 par = prz->par_buffer; 154 while (block < buffer->data + buffer_size(prz)) { 155 int numerr; 156 int size = prz->ecc_info.block_size; 157 if (block + size > buffer->data + prz->buffer_size) 158 size = buffer->data + prz->buffer_size - block; 159 numerr = persistent_ram_decode_rs8(prz, block, size, par); 160 if (numerr > 0) { 161 pr_devel("persistent_ram: error in block %p, %d\n", 162 block, numerr); 163 prz->corrected_bytes += numerr; 164 } else if (numerr < 0) { 165 pr_devel("persistent_ram: uncorrectable error in block %p\n", 166 block); 167 prz->bad_blocks++; 168 } 169 block += prz->ecc_info.block_size; 170 par += prz->ecc_info.ecc_size; 171 } 172 } 173 174 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz, 175 struct persistent_ram_ecc_info *ecc_info) 176 { 177 int numerr; 178 struct persistent_ram_buffer *buffer = prz->buffer; 179 int ecc_blocks; 180 size_t ecc_total; 181 182 if (!ecc_info || !ecc_info->ecc_size) 183 return 0; 184 185 prz->ecc_info.block_size = ecc_info->block_size ?: 128; 186 prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16; 187 prz->ecc_info.symsize = ecc_info->symsize ?: 8; 188 prz->ecc_info.poly = ecc_info->poly ?: 0x11d; 189 190 ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size, 191 prz->ecc_info.block_size + 192 prz->ecc_info.ecc_size); 193 ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size; 194 if (ecc_total >= prz->buffer_size) { 195 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n", 196 __func__, prz->ecc_info.ecc_size, 197 ecc_total, prz->buffer_size); 198 return -EINVAL; 199 } 200 201 prz->buffer_size -= ecc_total; 202 prz->par_buffer = buffer->data + prz->buffer_size; 203 prz->par_header = prz->par_buffer + 204 ecc_blocks * prz->ecc_info.ecc_size; 205 206 /* 207 * first consecutive root is 0 208 * primitive element to generate roots = 1 209 */ 210 prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly, 211 0, 1, prz->ecc_info.ecc_size); 212 if (prz->rs_decoder == NULL) { 213 pr_info("persistent_ram: init_rs failed\n"); 214 return -EINVAL; 215 } 216 217 prz->corrected_bytes = 0; 218 prz->bad_blocks = 0; 219 220 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer), 221 prz->par_header); 222 if (numerr > 0) { 223 pr_info("persistent_ram: error in header, %d\n", numerr); 224 prz->corrected_bytes += numerr; 225 } else if (numerr < 0) { 226 pr_info("persistent_ram: uncorrectable error in header\n"); 227 prz->bad_blocks++; 228 } 229 230 return 0; 231 } 232 233 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz, 234 char *str, size_t len) 235 { 236 ssize_t ret; 237 238 if (!prz->ecc_info.ecc_size) 239 return 0; 240 241 if (prz->corrected_bytes || prz->bad_blocks) 242 ret = snprintf(str, len, "" 243 "\n%d Corrected bytes, %d unrecoverable blocks\n", 244 prz->corrected_bytes, prz->bad_blocks); 245 else 246 ret = snprintf(str, len, "\nNo errors detected\n"); 247 248 return ret; 249 } 250 251 static void notrace persistent_ram_update(struct persistent_ram_zone *prz, 252 const void *s, unsigned int start, unsigned int count) 253 { 254 struct persistent_ram_buffer *buffer = prz->buffer; 255 memcpy(buffer->data + start, s, count); 256 persistent_ram_update_ecc(prz, start, count); 257 } 258 259 void persistent_ram_save_old(struct persistent_ram_zone *prz) 260 { 261 struct persistent_ram_buffer *buffer = prz->buffer; 262 size_t size = buffer_size(prz); 263 size_t start = buffer_start(prz); 264 265 if (!size) 266 return; 267 268 if (!prz->old_log) { 269 persistent_ram_ecc_old(prz); 270 prz->old_log = kmalloc(size, GFP_KERNEL); 271 } 272 if (!prz->old_log) { 273 pr_err("persistent_ram: failed to allocate buffer\n"); 274 return; 275 } 276 277 prz->old_log_size = size; 278 memcpy(prz->old_log, &buffer->data[start], size - start); 279 memcpy(prz->old_log + size - start, &buffer->data[0], start); 280 } 281 282 int notrace persistent_ram_write(struct persistent_ram_zone *prz, 283 const void *s, unsigned int count) 284 { 285 int rem; 286 int c = count; 287 size_t start; 288 289 if (unlikely(c > prz->buffer_size)) { 290 s += c - prz->buffer_size; 291 c = prz->buffer_size; 292 } 293 294 buffer_size_add(prz, c); 295 296 start = buffer_start_add(prz, c); 297 298 rem = prz->buffer_size - start; 299 if (unlikely(rem < c)) { 300 persistent_ram_update(prz, s, start, rem); 301 s += rem; 302 c -= rem; 303 start = 0; 304 } 305 persistent_ram_update(prz, s, start, c); 306 307 persistent_ram_update_header_ecc(prz); 308 309 return count; 310 } 311 312 size_t persistent_ram_old_size(struct persistent_ram_zone *prz) 313 { 314 return prz->old_log_size; 315 } 316 317 void *persistent_ram_old(struct persistent_ram_zone *prz) 318 { 319 return prz->old_log; 320 } 321 322 void persistent_ram_free_old(struct persistent_ram_zone *prz) 323 { 324 kfree(prz->old_log); 325 prz->old_log = NULL; 326 prz->old_log_size = 0; 327 } 328 329 void persistent_ram_zap(struct persistent_ram_zone *prz) 330 { 331 atomic_set(&prz->buffer->start, 0); 332 atomic_set(&prz->buffer->size, 0); 333 persistent_ram_update_header_ecc(prz); 334 } 335 336 static void *persistent_ram_vmap(phys_addr_t start, size_t size) 337 { 338 struct page **pages; 339 phys_addr_t page_start; 340 unsigned int page_count; 341 pgprot_t prot; 342 unsigned int i; 343 void *vaddr; 344 345 page_start = start - offset_in_page(start); 346 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE); 347 348 prot = pgprot_noncached(PAGE_KERNEL); 349 350 pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL); 351 if (!pages) { 352 pr_err("%s: Failed to allocate array for %u pages\n", __func__, 353 page_count); 354 return NULL; 355 } 356 357 for (i = 0; i < page_count; i++) { 358 phys_addr_t addr = page_start + i * PAGE_SIZE; 359 pages[i] = pfn_to_page(addr >> PAGE_SHIFT); 360 } 361 vaddr = vmap(pages, page_count, VM_MAP, prot); 362 kfree(pages); 363 364 return vaddr; 365 } 366 367 static void *persistent_ram_iomap(phys_addr_t start, size_t size) 368 { 369 if (!request_mem_region(start, size, "persistent_ram")) { 370 pr_err("request mem region (0x%llx@0x%llx) failed\n", 371 (unsigned long long)size, (unsigned long long)start); 372 return NULL; 373 } 374 375 return ioremap(start, size); 376 } 377 378 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size, 379 struct persistent_ram_zone *prz) 380 { 381 prz->paddr = start; 382 prz->size = size; 383 384 if (pfn_valid(start >> PAGE_SHIFT)) 385 prz->vaddr = persistent_ram_vmap(start, size); 386 else 387 prz->vaddr = persistent_ram_iomap(start, size); 388 389 if (!prz->vaddr) { 390 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__, 391 (unsigned long long)size, (unsigned long long)start); 392 return -ENOMEM; 393 } 394 395 prz->buffer = prz->vaddr + offset_in_page(start); 396 prz->buffer_size = size - sizeof(struct persistent_ram_buffer); 397 398 return 0; 399 } 400 401 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, 402 struct persistent_ram_ecc_info *ecc_info) 403 { 404 int ret; 405 406 ret = persistent_ram_init_ecc(prz, ecc_info); 407 if (ret) 408 return ret; 409 410 sig ^= PERSISTENT_RAM_SIG; 411 412 if (prz->buffer->sig == sig) { 413 if (buffer_size(prz) > prz->buffer_size || 414 buffer_start(prz) > buffer_size(prz)) 415 pr_info("persistent_ram: found existing invalid buffer," 416 " size %zu, start %zu\n", 417 buffer_size(prz), buffer_start(prz)); 418 else { 419 pr_debug("persistent_ram: found existing buffer," 420 " size %zu, start %zu\n", 421 buffer_size(prz), buffer_start(prz)); 422 persistent_ram_save_old(prz); 423 return 0; 424 } 425 } else { 426 pr_debug("persistent_ram: no valid data in buffer" 427 " (sig = 0x%08x)\n", prz->buffer->sig); 428 } 429 430 prz->buffer->sig = sig; 431 persistent_ram_zap(prz); 432 433 return 0; 434 } 435 436 void persistent_ram_free(struct persistent_ram_zone *prz) 437 { 438 if (!prz) 439 return; 440 441 if (prz->vaddr) { 442 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) { 443 vunmap(prz->vaddr); 444 } else { 445 iounmap(prz->vaddr); 446 release_mem_region(prz->paddr, prz->size); 447 } 448 prz->vaddr = NULL; 449 } 450 persistent_ram_free_old(prz); 451 kfree(prz); 452 } 453 454 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size, 455 u32 sig, struct persistent_ram_ecc_info *ecc_info) 456 { 457 struct persistent_ram_zone *prz; 458 int ret = -ENOMEM; 459 460 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL); 461 if (!prz) { 462 pr_err("persistent_ram: failed to allocate persistent ram zone\n"); 463 goto err; 464 } 465 466 ret = persistent_ram_buffer_map(start, size, prz); 467 if (ret) 468 goto err; 469 470 ret = persistent_ram_post_init(prz, sig, ecc_info); 471 if (ret) 472 goto err; 473 474 return prz; 475 err: 476 persistent_ram_free(prz); 477 return ERR_PTR(ret); 478 } 479