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 size_t buffer_start_add_atomic(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 void buffer_size_add_atomic(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 DEFINE_RAW_SPINLOCK(buffer_lock); 82 83 /* increase and wrap the start pointer, returning the old value */ 84 static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a) 85 { 86 int old; 87 int new; 88 unsigned long flags; 89 90 raw_spin_lock_irqsave(&buffer_lock, flags); 91 92 old = atomic_read(&prz->buffer->start); 93 new = old + a; 94 while (unlikely(new > prz->buffer_size)) 95 new -= prz->buffer_size; 96 atomic_set(&prz->buffer->start, new); 97 98 raw_spin_unlock_irqrestore(&buffer_lock, flags); 99 100 return old; 101 } 102 103 /* increase the size counter until it hits the max size */ 104 static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a) 105 { 106 size_t old; 107 size_t new; 108 unsigned long flags; 109 110 raw_spin_lock_irqsave(&buffer_lock, flags); 111 112 old = atomic_read(&prz->buffer->size); 113 if (old == prz->buffer_size) 114 goto exit; 115 116 new = old + a; 117 if (new > prz->buffer_size) 118 new = prz->buffer_size; 119 atomic_set(&prz->buffer->size, new); 120 121 exit: 122 raw_spin_unlock_irqrestore(&buffer_lock, flags); 123 } 124 125 static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic; 126 static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic; 127 128 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, 129 uint8_t *data, size_t len, uint8_t *ecc) 130 { 131 int i; 132 uint16_t par[prz->ecc_info.ecc_size]; 133 134 /* Initialize the parity buffer */ 135 memset(par, 0, sizeof(par)); 136 encode_rs8(prz->rs_decoder, data, len, par, 0); 137 for (i = 0; i < prz->ecc_info.ecc_size; i++) 138 ecc[i] = par[i]; 139 } 140 141 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz, 142 void *data, size_t len, uint8_t *ecc) 143 { 144 int i; 145 uint16_t par[prz->ecc_info.ecc_size]; 146 147 for (i = 0; i < prz->ecc_info.ecc_size; i++) 148 par[i] = ecc[i]; 149 return decode_rs8(prz->rs_decoder, data, par, len, 150 NULL, 0, NULL, 0, NULL); 151 } 152 153 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz, 154 unsigned int start, unsigned int count) 155 { 156 struct persistent_ram_buffer *buffer = prz->buffer; 157 uint8_t *buffer_end = buffer->data + prz->buffer_size; 158 uint8_t *block; 159 uint8_t *par; 160 int ecc_block_size = prz->ecc_info.block_size; 161 int ecc_size = prz->ecc_info.ecc_size; 162 int size = ecc_block_size; 163 164 if (!ecc_size) 165 return; 166 167 block = buffer->data + (start & ~(ecc_block_size - 1)); 168 par = prz->par_buffer + (start / ecc_block_size) * ecc_size; 169 170 do { 171 if (block + ecc_block_size > buffer_end) 172 size = buffer_end - block; 173 persistent_ram_encode_rs8(prz, block, size, par); 174 block += ecc_block_size; 175 par += ecc_size; 176 } while (block < buffer->data + start + count); 177 } 178 179 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz) 180 { 181 struct persistent_ram_buffer *buffer = prz->buffer; 182 183 if (!prz->ecc_info.ecc_size) 184 return; 185 186 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer), 187 prz->par_header); 188 } 189 190 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz) 191 { 192 struct persistent_ram_buffer *buffer = prz->buffer; 193 uint8_t *block; 194 uint8_t *par; 195 196 if (!prz->ecc_info.ecc_size) 197 return; 198 199 block = buffer->data; 200 par = prz->par_buffer; 201 while (block < buffer->data + buffer_size(prz)) { 202 int numerr; 203 int size = prz->ecc_info.block_size; 204 if (block + size > buffer->data + prz->buffer_size) 205 size = buffer->data + prz->buffer_size - block; 206 numerr = persistent_ram_decode_rs8(prz, block, size, par); 207 if (numerr > 0) { 208 pr_devel("persistent_ram: error in block %p, %d\n", 209 block, numerr); 210 prz->corrected_bytes += numerr; 211 } else if (numerr < 0) { 212 pr_devel("persistent_ram: uncorrectable error in block %p\n", 213 block); 214 prz->bad_blocks++; 215 } 216 block += prz->ecc_info.block_size; 217 par += prz->ecc_info.ecc_size; 218 } 219 } 220 221 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz, 222 struct persistent_ram_ecc_info *ecc_info) 223 { 224 int numerr; 225 struct persistent_ram_buffer *buffer = prz->buffer; 226 int ecc_blocks; 227 size_t ecc_total; 228 229 if (!ecc_info || !ecc_info->ecc_size) 230 return 0; 231 232 prz->ecc_info.block_size = ecc_info->block_size ?: 128; 233 prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16; 234 prz->ecc_info.symsize = ecc_info->symsize ?: 8; 235 prz->ecc_info.poly = ecc_info->poly ?: 0x11d; 236 237 ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size, 238 prz->ecc_info.block_size + 239 prz->ecc_info.ecc_size); 240 ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size; 241 if (ecc_total >= prz->buffer_size) { 242 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n", 243 __func__, prz->ecc_info.ecc_size, 244 ecc_total, prz->buffer_size); 245 return -EINVAL; 246 } 247 248 prz->buffer_size -= ecc_total; 249 prz->par_buffer = buffer->data + prz->buffer_size; 250 prz->par_header = prz->par_buffer + 251 ecc_blocks * prz->ecc_info.ecc_size; 252 253 /* 254 * first consecutive root is 0 255 * primitive element to generate roots = 1 256 */ 257 prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly, 258 0, 1, prz->ecc_info.ecc_size); 259 if (prz->rs_decoder == NULL) { 260 pr_info("persistent_ram: init_rs failed\n"); 261 return -EINVAL; 262 } 263 264 prz->corrected_bytes = 0; 265 prz->bad_blocks = 0; 266 267 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer), 268 prz->par_header); 269 if (numerr > 0) { 270 pr_info("persistent_ram: error in header, %d\n", numerr); 271 prz->corrected_bytes += numerr; 272 } else if (numerr < 0) { 273 pr_info("persistent_ram: uncorrectable error in header\n"); 274 prz->bad_blocks++; 275 } 276 277 return 0; 278 } 279 280 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz, 281 char *str, size_t len) 282 { 283 ssize_t ret; 284 285 if (!prz->ecc_info.ecc_size) 286 return 0; 287 288 if (prz->corrected_bytes || prz->bad_blocks) 289 ret = snprintf(str, len, "" 290 "\n%d Corrected bytes, %d unrecoverable blocks\n", 291 prz->corrected_bytes, prz->bad_blocks); 292 else 293 ret = snprintf(str, len, "\nNo errors detected\n"); 294 295 return ret; 296 } 297 298 static void notrace persistent_ram_update(struct persistent_ram_zone *prz, 299 const void *s, unsigned int start, unsigned int count) 300 { 301 struct persistent_ram_buffer *buffer = prz->buffer; 302 memcpy(buffer->data + start, s, count); 303 persistent_ram_update_ecc(prz, start, count); 304 } 305 306 void persistent_ram_save_old(struct persistent_ram_zone *prz) 307 { 308 struct persistent_ram_buffer *buffer = prz->buffer; 309 size_t size = buffer_size(prz); 310 size_t start = buffer_start(prz); 311 312 if (!size) 313 return; 314 315 if (!prz->old_log) { 316 persistent_ram_ecc_old(prz); 317 prz->old_log = kmalloc(size, GFP_KERNEL); 318 } 319 if (!prz->old_log) { 320 pr_err("persistent_ram: failed to allocate buffer\n"); 321 return; 322 } 323 324 prz->old_log_size = size; 325 memcpy(prz->old_log, &buffer->data[start], size - start); 326 memcpy(prz->old_log + size - start, &buffer->data[0], start); 327 } 328 329 int notrace persistent_ram_write(struct persistent_ram_zone *prz, 330 const void *s, unsigned int count) 331 { 332 int rem; 333 int c = count; 334 size_t start; 335 336 if (unlikely(c > prz->buffer_size)) { 337 s += c - prz->buffer_size; 338 c = prz->buffer_size; 339 } 340 341 buffer_size_add(prz, c); 342 343 start = buffer_start_add(prz, c); 344 345 rem = prz->buffer_size - start; 346 if (unlikely(rem < c)) { 347 persistent_ram_update(prz, s, start, rem); 348 s += rem; 349 c -= rem; 350 start = 0; 351 } 352 persistent_ram_update(prz, s, start, c); 353 354 persistent_ram_update_header_ecc(prz); 355 356 return count; 357 } 358 359 size_t persistent_ram_old_size(struct persistent_ram_zone *prz) 360 { 361 return prz->old_log_size; 362 } 363 364 void *persistent_ram_old(struct persistent_ram_zone *prz) 365 { 366 return prz->old_log; 367 } 368 369 void persistent_ram_free_old(struct persistent_ram_zone *prz) 370 { 371 kfree(prz->old_log); 372 prz->old_log = NULL; 373 prz->old_log_size = 0; 374 } 375 376 void persistent_ram_zap(struct persistent_ram_zone *prz) 377 { 378 atomic_set(&prz->buffer->start, 0); 379 atomic_set(&prz->buffer->size, 0); 380 persistent_ram_update_header_ecc(prz); 381 } 382 383 static void *persistent_ram_vmap(phys_addr_t start, size_t size) 384 { 385 struct page **pages; 386 phys_addr_t page_start; 387 unsigned int page_count; 388 pgprot_t prot; 389 unsigned int i; 390 void *vaddr; 391 392 page_start = start - offset_in_page(start); 393 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE); 394 395 prot = pgprot_noncached(PAGE_KERNEL); 396 397 pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL); 398 if (!pages) { 399 pr_err("%s: Failed to allocate array for %u pages\n", __func__, 400 page_count); 401 return NULL; 402 } 403 404 for (i = 0; i < page_count; i++) { 405 phys_addr_t addr = page_start + i * PAGE_SIZE; 406 pages[i] = pfn_to_page(addr >> PAGE_SHIFT); 407 } 408 vaddr = vmap(pages, page_count, VM_MAP, prot); 409 kfree(pages); 410 411 return vaddr; 412 } 413 414 static void *persistent_ram_iomap(phys_addr_t start, size_t size) 415 { 416 if (!request_mem_region(start, size, "persistent_ram")) { 417 pr_err("request mem region (0x%llx@0x%llx) failed\n", 418 (unsigned long long)size, (unsigned long long)start); 419 return NULL; 420 } 421 422 buffer_start_add = buffer_start_add_locked; 423 buffer_size_add = buffer_size_add_locked; 424 425 return ioremap(start, size); 426 } 427 428 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size, 429 struct persistent_ram_zone *prz) 430 { 431 prz->paddr = start; 432 prz->size = size; 433 434 if (pfn_valid(start >> PAGE_SHIFT)) 435 prz->vaddr = persistent_ram_vmap(start, size); 436 else 437 prz->vaddr = persistent_ram_iomap(start, size); 438 439 if (!prz->vaddr) { 440 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__, 441 (unsigned long long)size, (unsigned long long)start); 442 return -ENOMEM; 443 } 444 445 prz->buffer = prz->vaddr + offset_in_page(start); 446 prz->buffer_size = size - sizeof(struct persistent_ram_buffer); 447 448 return 0; 449 } 450 451 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, 452 struct persistent_ram_ecc_info *ecc_info) 453 { 454 int ret; 455 456 ret = persistent_ram_init_ecc(prz, ecc_info); 457 if (ret) 458 return ret; 459 460 sig ^= PERSISTENT_RAM_SIG; 461 462 if (prz->buffer->sig == sig) { 463 if (buffer_size(prz) > prz->buffer_size || 464 buffer_start(prz) > buffer_size(prz)) 465 pr_info("persistent_ram: found existing invalid buffer," 466 " size %zu, start %zu\n", 467 buffer_size(prz), buffer_start(prz)); 468 else { 469 pr_debug("persistent_ram: found existing buffer," 470 " size %zu, start %zu\n", 471 buffer_size(prz), buffer_start(prz)); 472 persistent_ram_save_old(prz); 473 return 0; 474 } 475 } else { 476 pr_debug("persistent_ram: no valid data in buffer" 477 " (sig = 0x%08x)\n", prz->buffer->sig); 478 } 479 480 prz->buffer->sig = sig; 481 persistent_ram_zap(prz); 482 483 return 0; 484 } 485 486 void persistent_ram_free(struct persistent_ram_zone *prz) 487 { 488 if (!prz) 489 return; 490 491 if (prz->vaddr) { 492 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) { 493 vunmap(prz->vaddr); 494 } else { 495 iounmap(prz->vaddr); 496 release_mem_region(prz->paddr, prz->size); 497 } 498 prz->vaddr = NULL; 499 } 500 persistent_ram_free_old(prz); 501 kfree(prz); 502 } 503 504 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size, 505 u32 sig, struct persistent_ram_ecc_info *ecc_info) 506 { 507 struct persistent_ram_zone *prz; 508 int ret = -ENOMEM; 509 510 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL); 511 if (!prz) { 512 pr_err("persistent_ram: failed to allocate persistent ram zone\n"); 513 goto err; 514 } 515 516 ret = persistent_ram_buffer_map(start, size, prz); 517 if (ret) 518 goto err; 519 520 ret = persistent_ram_post_init(prz, sig, ecc_info); 521 if (ret) 522 goto err; 523 524 return prz; 525 err: 526 persistent_ram_free(prz); 527 return ERR_PTR(ret); 528 } 529