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