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 #define pr_fmt(fmt) "persistent_ram: " fmt 16 17 #include <linux/device.h> 18 #include <linux/err.h> 19 #include <linux/errno.h> 20 #include <linux/init.h> 21 #include <linux/io.h> 22 #include <linux/kernel.h> 23 #include <linux/list.h> 24 #include <linux/memblock.h> 25 #include <linux/pstore_ram.h> 26 #include <linux/rslib.h> 27 #include <linux/slab.h> 28 #include <linux/uaccess.h> 29 #include <linux/vmalloc.h> 30 #include <asm/page.h> 31 32 struct persistent_ram_buffer { 33 uint32_t sig; 34 atomic_t start; 35 atomic_t size; 36 uint8_t data[0]; 37 }; 38 39 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */ 40 41 static inline size_t buffer_size(struct persistent_ram_zone *prz) 42 { 43 return atomic_read(&prz->buffer->size); 44 } 45 46 static inline size_t buffer_start(struct persistent_ram_zone *prz) 47 { 48 return atomic_read(&prz->buffer->start); 49 } 50 51 /* increase and wrap the start pointer, returning the old value */ 52 static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a) 53 { 54 int old; 55 int new; 56 unsigned long flags = 0; 57 58 if (!(prz->flags & PRZ_FLAG_NO_LOCK)) 59 raw_spin_lock_irqsave(&prz->buffer_lock, flags); 60 61 old = atomic_read(&prz->buffer->start); 62 new = old + a; 63 while (unlikely(new >= prz->buffer_size)) 64 new -= prz->buffer_size; 65 atomic_set(&prz->buffer->start, new); 66 67 if (!(prz->flags & PRZ_FLAG_NO_LOCK)) 68 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags); 69 70 return old; 71 } 72 73 /* increase the size counter until it hits the max size */ 74 static void buffer_size_add(struct persistent_ram_zone *prz, size_t a) 75 { 76 size_t old; 77 size_t new; 78 unsigned long flags = 0; 79 80 if (!(prz->flags & PRZ_FLAG_NO_LOCK)) 81 raw_spin_lock_irqsave(&prz->buffer_lock, flags); 82 83 old = atomic_read(&prz->buffer->size); 84 if (old == prz->buffer_size) 85 goto exit; 86 87 new = old + a; 88 if (new > prz->buffer_size) 89 new = prz->buffer_size; 90 atomic_set(&prz->buffer->size, new); 91 92 exit: 93 if (!(prz->flags & PRZ_FLAG_NO_LOCK)) 94 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags); 95 } 96 97 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, 98 uint8_t *data, size_t len, uint8_t *ecc) 99 { 100 int i; 101 uint16_t par[prz->ecc_info.ecc_size]; 102 103 /* Initialize the parity buffer */ 104 memset(par, 0, sizeof(par)); 105 encode_rs8(prz->rs_decoder, data, len, par, 0); 106 for (i = 0; i < prz->ecc_info.ecc_size; i++) 107 ecc[i] = par[i]; 108 } 109 110 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz, 111 void *data, size_t len, uint8_t *ecc) 112 { 113 int i; 114 uint16_t par[prz->ecc_info.ecc_size]; 115 116 for (i = 0; i < prz->ecc_info.ecc_size; i++) 117 par[i] = ecc[i]; 118 return decode_rs8(prz->rs_decoder, data, par, len, 119 NULL, 0, NULL, 0, NULL); 120 } 121 122 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz, 123 unsigned int start, unsigned int count) 124 { 125 struct persistent_ram_buffer *buffer = prz->buffer; 126 uint8_t *buffer_end = buffer->data + prz->buffer_size; 127 uint8_t *block; 128 uint8_t *par; 129 int ecc_block_size = prz->ecc_info.block_size; 130 int ecc_size = prz->ecc_info.ecc_size; 131 int size = ecc_block_size; 132 133 if (!ecc_size) 134 return; 135 136 block = buffer->data + (start & ~(ecc_block_size - 1)); 137 par = prz->par_buffer + (start / ecc_block_size) * ecc_size; 138 139 do { 140 if (block + ecc_block_size > buffer_end) 141 size = buffer_end - block; 142 persistent_ram_encode_rs8(prz, block, size, par); 143 block += ecc_block_size; 144 par += ecc_size; 145 } while (block < buffer->data + start + count); 146 } 147 148 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz) 149 { 150 struct persistent_ram_buffer *buffer = prz->buffer; 151 152 if (!prz->ecc_info.ecc_size) 153 return; 154 155 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer), 156 prz->par_header); 157 } 158 159 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz) 160 { 161 struct persistent_ram_buffer *buffer = prz->buffer; 162 uint8_t *block; 163 uint8_t *par; 164 165 if (!prz->ecc_info.ecc_size) 166 return; 167 168 block = buffer->data; 169 par = prz->par_buffer; 170 while (block < buffer->data + buffer_size(prz)) { 171 int numerr; 172 int size = prz->ecc_info.block_size; 173 if (block + size > buffer->data + prz->buffer_size) 174 size = buffer->data + prz->buffer_size - block; 175 numerr = persistent_ram_decode_rs8(prz, block, size, par); 176 if (numerr > 0) { 177 pr_devel("error in block %p, %d\n", block, numerr); 178 prz->corrected_bytes += numerr; 179 } else if (numerr < 0) { 180 pr_devel("uncorrectable error in block %p\n", block); 181 prz->bad_blocks++; 182 } 183 block += prz->ecc_info.block_size; 184 par += prz->ecc_info.ecc_size; 185 } 186 } 187 188 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz, 189 struct persistent_ram_ecc_info *ecc_info) 190 { 191 int numerr; 192 struct persistent_ram_buffer *buffer = prz->buffer; 193 int ecc_blocks; 194 size_t ecc_total; 195 196 if (!ecc_info || !ecc_info->ecc_size) 197 return 0; 198 199 prz->ecc_info.block_size = ecc_info->block_size ?: 128; 200 prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16; 201 prz->ecc_info.symsize = ecc_info->symsize ?: 8; 202 prz->ecc_info.poly = ecc_info->poly ?: 0x11d; 203 204 ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size, 205 prz->ecc_info.block_size + 206 prz->ecc_info.ecc_size); 207 ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size; 208 if (ecc_total >= prz->buffer_size) { 209 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n", 210 __func__, prz->ecc_info.ecc_size, 211 ecc_total, prz->buffer_size); 212 return -EINVAL; 213 } 214 215 prz->buffer_size -= ecc_total; 216 prz->par_buffer = buffer->data + prz->buffer_size; 217 prz->par_header = prz->par_buffer + 218 ecc_blocks * prz->ecc_info.ecc_size; 219 220 /* 221 * first consecutive root is 0 222 * primitive element to generate roots = 1 223 */ 224 prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly, 225 0, 1, prz->ecc_info.ecc_size); 226 if (prz->rs_decoder == NULL) { 227 pr_info("init_rs failed\n"); 228 return -EINVAL; 229 } 230 231 prz->corrected_bytes = 0; 232 prz->bad_blocks = 0; 233 234 numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer), 235 prz->par_header); 236 if (numerr > 0) { 237 pr_info("error in header, %d\n", numerr); 238 prz->corrected_bytes += numerr; 239 } else if (numerr < 0) { 240 pr_info("uncorrectable error in header\n"); 241 prz->bad_blocks++; 242 } 243 244 return 0; 245 } 246 247 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz, 248 char *str, size_t len) 249 { 250 ssize_t ret; 251 252 if (!prz->ecc_info.ecc_size) 253 return 0; 254 255 if (prz->corrected_bytes || prz->bad_blocks) 256 ret = snprintf(str, len, "" 257 "\n%d Corrected bytes, %d unrecoverable blocks\n", 258 prz->corrected_bytes, prz->bad_blocks); 259 else 260 ret = snprintf(str, len, "\nNo errors detected\n"); 261 262 return ret; 263 } 264 265 static void notrace persistent_ram_update(struct persistent_ram_zone *prz, 266 const void *s, unsigned int start, unsigned int count) 267 { 268 struct persistent_ram_buffer *buffer = prz->buffer; 269 memcpy_toio(buffer->data + start, s, count); 270 persistent_ram_update_ecc(prz, start, count); 271 } 272 273 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz, 274 const void __user *s, unsigned int start, unsigned int count) 275 { 276 struct persistent_ram_buffer *buffer = prz->buffer; 277 int ret = unlikely(__copy_from_user(buffer->data + start, s, count)) ? 278 -EFAULT : 0; 279 persistent_ram_update_ecc(prz, start, count); 280 return ret; 281 } 282 283 void persistent_ram_save_old(struct persistent_ram_zone *prz) 284 { 285 struct persistent_ram_buffer *buffer = prz->buffer; 286 size_t size = buffer_size(prz); 287 size_t start = buffer_start(prz); 288 289 if (!size) 290 return; 291 292 if (!prz->old_log) { 293 persistent_ram_ecc_old(prz); 294 prz->old_log = kmalloc(size, GFP_KERNEL); 295 } 296 if (!prz->old_log) { 297 pr_err("failed to allocate buffer\n"); 298 return; 299 } 300 301 prz->old_log_size = size; 302 memcpy_fromio(prz->old_log, &buffer->data[start], size - start); 303 memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start); 304 } 305 306 int notrace persistent_ram_write(struct persistent_ram_zone *prz, 307 const void *s, unsigned int count) 308 { 309 int rem; 310 int c = count; 311 size_t start; 312 313 if (unlikely(c > prz->buffer_size)) { 314 s += c - prz->buffer_size; 315 c = prz->buffer_size; 316 } 317 318 buffer_size_add(prz, c); 319 320 start = buffer_start_add(prz, c); 321 322 rem = prz->buffer_size - start; 323 if (unlikely(rem < c)) { 324 persistent_ram_update(prz, s, start, rem); 325 s += rem; 326 c -= rem; 327 start = 0; 328 } 329 persistent_ram_update(prz, s, start, c); 330 331 persistent_ram_update_header_ecc(prz); 332 333 return count; 334 } 335 336 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz, 337 const void __user *s, unsigned int count) 338 { 339 int rem, ret = 0, c = count; 340 size_t start; 341 342 if (unlikely(!access_ok(VERIFY_READ, s, count))) 343 return -EFAULT; 344 if (unlikely(c > prz->buffer_size)) { 345 s += c - prz->buffer_size; 346 c = prz->buffer_size; 347 } 348 349 buffer_size_add(prz, c); 350 351 start = buffer_start_add(prz, c); 352 353 rem = prz->buffer_size - start; 354 if (unlikely(rem < c)) { 355 ret = persistent_ram_update_user(prz, s, start, rem); 356 s += rem; 357 c -= rem; 358 start = 0; 359 } 360 if (likely(!ret)) 361 ret = persistent_ram_update_user(prz, s, start, c); 362 363 persistent_ram_update_header_ecc(prz); 364 365 return unlikely(ret) ? ret : count; 366 } 367 368 size_t persistent_ram_old_size(struct persistent_ram_zone *prz) 369 { 370 return prz->old_log_size; 371 } 372 373 void *persistent_ram_old(struct persistent_ram_zone *prz) 374 { 375 return prz->old_log; 376 } 377 378 void persistent_ram_free_old(struct persistent_ram_zone *prz) 379 { 380 kfree(prz->old_log); 381 prz->old_log = NULL; 382 prz->old_log_size = 0; 383 } 384 385 void persistent_ram_zap(struct persistent_ram_zone *prz) 386 { 387 atomic_set(&prz->buffer->start, 0); 388 atomic_set(&prz->buffer->size, 0); 389 persistent_ram_update_header_ecc(prz); 390 } 391 392 static void *persistent_ram_vmap(phys_addr_t start, size_t size, 393 unsigned int memtype) 394 { 395 struct page **pages; 396 phys_addr_t page_start; 397 unsigned int page_count; 398 pgprot_t prot; 399 unsigned int i; 400 void *vaddr; 401 402 page_start = start - offset_in_page(start); 403 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE); 404 405 if (memtype) 406 prot = pgprot_noncached(PAGE_KERNEL); 407 else 408 prot = pgprot_writecombine(PAGE_KERNEL); 409 410 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL); 411 if (!pages) { 412 pr_err("%s: Failed to allocate array for %u pages\n", 413 __func__, page_count); 414 return NULL; 415 } 416 417 for (i = 0; i < page_count; i++) { 418 phys_addr_t addr = page_start + i * PAGE_SIZE; 419 pages[i] = pfn_to_page(addr >> PAGE_SHIFT); 420 } 421 vaddr = vmap(pages, page_count, VM_MAP, prot); 422 kfree(pages); 423 424 return vaddr; 425 } 426 427 static void *persistent_ram_iomap(phys_addr_t start, size_t size, 428 unsigned int memtype) 429 { 430 void *va; 431 432 if (!request_mem_region(start, size, "persistent_ram")) { 433 pr_err("request mem region (0x%llx@0x%llx) failed\n", 434 (unsigned long long)size, (unsigned long long)start); 435 return NULL; 436 } 437 438 if (memtype) 439 va = ioremap(start, size); 440 else 441 va = ioremap_wc(start, size); 442 443 return va; 444 } 445 446 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size, 447 struct persistent_ram_zone *prz, int memtype) 448 { 449 prz->paddr = start; 450 prz->size = size; 451 452 if (pfn_valid(start >> PAGE_SHIFT)) 453 prz->vaddr = persistent_ram_vmap(start, size, memtype); 454 else 455 prz->vaddr = persistent_ram_iomap(start, size, memtype); 456 457 if (!prz->vaddr) { 458 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__, 459 (unsigned long long)size, (unsigned long long)start); 460 return -ENOMEM; 461 } 462 463 prz->buffer = prz->vaddr + offset_in_page(start); 464 prz->buffer_size = size - sizeof(struct persistent_ram_buffer); 465 466 return 0; 467 } 468 469 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, 470 struct persistent_ram_ecc_info *ecc_info) 471 { 472 int ret; 473 474 ret = persistent_ram_init_ecc(prz, ecc_info); 475 if (ret) 476 return ret; 477 478 sig ^= PERSISTENT_RAM_SIG; 479 480 if (prz->buffer->sig == sig) { 481 if (buffer_size(prz) > prz->buffer_size || 482 buffer_start(prz) > buffer_size(prz)) 483 pr_info("found existing invalid buffer, size %zu, start %zu\n", 484 buffer_size(prz), buffer_start(prz)); 485 else { 486 pr_debug("found existing buffer, size %zu, start %zu\n", 487 buffer_size(prz), buffer_start(prz)); 488 persistent_ram_save_old(prz); 489 return 0; 490 } 491 } else { 492 pr_debug("no valid data in buffer (sig = 0x%08x)\n", 493 prz->buffer->sig); 494 } 495 496 /* Rewind missing or invalid memory area. */ 497 prz->buffer->sig = sig; 498 persistent_ram_zap(prz); 499 500 return 0; 501 } 502 503 void persistent_ram_free(struct persistent_ram_zone *prz) 504 { 505 if (!prz) 506 return; 507 508 if (prz->vaddr) { 509 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) { 510 vunmap(prz->vaddr); 511 } else { 512 iounmap(prz->vaddr); 513 release_mem_region(prz->paddr, prz->size); 514 } 515 prz->vaddr = NULL; 516 } 517 persistent_ram_free_old(prz); 518 kfree(prz); 519 } 520 521 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size, 522 u32 sig, struct persistent_ram_ecc_info *ecc_info, 523 unsigned int memtype, u32 flags) 524 { 525 struct persistent_ram_zone *prz; 526 int ret = -ENOMEM; 527 528 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL); 529 if (!prz) { 530 pr_err("failed to allocate persistent ram zone\n"); 531 goto err; 532 } 533 534 /* Initialize general buffer state. */ 535 raw_spin_lock_init(&prz->buffer_lock); 536 prz->flags = flags; 537 538 ret = persistent_ram_buffer_map(start, size, prz, memtype); 539 if (ret) 540 goto err; 541 542 ret = persistent_ram_post_init(prz, sig, ecc_info); 543 if (ret) 544 goto err; 545 546 return prz; 547 err: 548 persistent_ram_free(prz); 549 return ERR_PTR(ret); 550 } 551