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/kernel.h> 21#include <linux/init.h> 22#include <linux/io.h> 23#include <linux/list.h> 24#include <linux/memblock.h> 25#include <linux/rslib.h> 26#include <linux/slab.h> 27#include <linux/vmalloc.h> 28#include <linux/pstore_ram.h> 29#include <asm/page.h> 30 31struct persistent_ram_buffer { 32 uint32_t sig; 33 atomic_t start; 34 atomic_t size; 35 uint8_t data[0]; 36}; 37 38#define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */ 39 40static inline size_t buffer_size(struct persistent_ram_zone *prz) 41{ 42 return atomic_read(&prz->buffer->size); 43} 44 45static inline size_t buffer_start(struct persistent_ram_zone *prz) 46{ 47 return atomic_read(&prz->buffer->start); 48} 49 50/* increase and wrap the start pointer, returning the old value */ 51static size_t buffer_start_add_atomic(struct persistent_ram_zone *prz, size_t a) 52{ 53 int old; 54 int new; 55 56 do { 57 old = atomic_read(&prz->buffer->start); 58 new = old + a; 59 while (unlikely(new >= prz->buffer_size)) 60 new -= prz->buffer_size; 61 } while (atomic_cmpxchg(&prz->buffer->start, old, new) != old); 62 63 return old; 64} 65 66/* increase the size counter until it hits the max size */ 67static void buffer_size_add_atomic(struct persistent_ram_zone *prz, size_t a) 68{ 69 size_t old; 70 size_t new; 71 72 if (atomic_read(&prz->buffer->size) == prz->buffer_size) 73 return; 74 75 do { 76 old = atomic_read(&prz->buffer->size); 77 new = old + a; 78 if (new > prz->buffer_size) 79 new = prz->buffer_size; 80 } while (atomic_cmpxchg(&prz->buffer->size, old, new) != old); 81} 82 83static DEFINE_RAW_SPINLOCK(buffer_lock); 84 85/* increase and wrap the start pointer, returning the old value */ 86static size_t buffer_start_add_locked(struct persistent_ram_zone *prz, size_t a) 87{ 88 int old; 89 int new; 90 unsigned long flags; 91 92 raw_spin_lock_irqsave(&buffer_lock, flags); 93 94 old = atomic_read(&prz->buffer->start); 95 new = old + a; 96 while (unlikely(new >= prz->buffer_size)) 97 new -= prz->buffer_size; 98 atomic_set(&prz->buffer->start, new); 99 100 raw_spin_unlock_irqrestore(&buffer_lock, flags); 101 102 return old; 103} 104 105/* increase the size counter until it hits the max size */ 106static void buffer_size_add_locked(struct persistent_ram_zone *prz, size_t a) 107{ 108 size_t old; 109 size_t new; 110 unsigned long flags; 111 112 raw_spin_lock_irqsave(&buffer_lock, flags); 113 114 old = atomic_read(&prz->buffer->size); 115 if (old == prz->buffer_size) 116 goto exit; 117 118 new = old + a; 119 if (new > prz->buffer_size) 120 new = prz->buffer_size; 121 atomic_set(&prz->buffer->size, new); 122 123exit: 124 raw_spin_unlock_irqrestore(&buffer_lock, flags); 125} 126 127static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic; 128static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic; 129 130static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz, 131 uint8_t *data, size_t len, uint8_t *ecc) 132{ 133 int i; 134 uint16_t par[prz->ecc_info.ecc_size]; 135 136 /* Initialize the parity buffer */ 137 memset(par, 0, sizeof(par)); 138 encode_rs8(prz->rs_decoder, data, len, par, 0); 139 for (i = 0; i < prz->ecc_info.ecc_size; i++) 140 ecc[i] = par[i]; 141} 142 143static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz, 144 void *data, size_t len, uint8_t *ecc) 145{ 146 int i; 147 uint16_t par[prz->ecc_info.ecc_size]; 148 149 for (i = 0; i < prz->ecc_info.ecc_size; i++) 150 par[i] = ecc[i]; 151 return decode_rs8(prz->rs_decoder, data, par, len, 152 NULL, 0, NULL, 0, NULL); 153} 154 155static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz, 156 unsigned int start, unsigned int count) 157{ 158 struct persistent_ram_buffer *buffer = prz->buffer; 159 uint8_t *buffer_end = buffer->data + prz->buffer_size; 160 uint8_t *block; 161 uint8_t *par; 162 int ecc_block_size = prz->ecc_info.block_size; 163 int ecc_size = prz->ecc_info.ecc_size; 164 int size = ecc_block_size; 165 166 if (!ecc_size) 167 return; 168 169 block = buffer->data + (start & ~(ecc_block_size - 1)); 170 par = prz->par_buffer + (start / ecc_block_size) * ecc_size; 171 172 do { 173 if (block + ecc_block_size > buffer_end) 174 size = buffer_end - block; 175 persistent_ram_encode_rs8(prz, block, size, par); 176 block += ecc_block_size; 177 par += ecc_size; 178 } while (block < buffer->data + start + count); 179} 180 181static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz) 182{ 183 struct persistent_ram_buffer *buffer = prz->buffer; 184 185 if (!prz->ecc_info.ecc_size) 186 return; 187 188 persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer), 189 prz->par_header); 190} 191 192static void persistent_ram_ecc_old(struct persistent_ram_zone *prz) 193{ 194 struct persistent_ram_buffer *buffer = prz->buffer; 195 uint8_t *block; 196 uint8_t *par; 197 198 if (!prz->ecc_info.ecc_size) 199 return; 200 201 block = buffer->data; 202 par = prz->par_buffer; 203 while (block < buffer->data + buffer_size(prz)) { 204 int numerr; 205 int size = prz->ecc_info.block_size; 206 if (block + size > buffer->data + prz->buffer_size) 207 size = buffer->data + prz->buffer_size - block; 208 numerr = persistent_ram_decode_rs8(prz, block, size, par); 209 if (numerr > 0) { 210 pr_devel("error in block %p, %d\n", block, numerr); 211 prz->corrected_bytes += numerr; 212 } else if (numerr < 0) { 213 pr_devel("uncorrectable error in block %p\n", block); 214 prz->bad_blocks++; 215 } 216 block += prz->ecc_info.block_size; 217 par += prz->ecc_info.ecc_size; 218 } 219} 220 221static 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("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("error in header, %d\n", numerr); 271 prz->corrected_bytes += numerr; 272 } else if (numerr < 0) { 273 pr_info("uncorrectable error in header\n"); 274 prz->bad_blocks++; 275 } 276 277 return 0; 278} 279 280ssize_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 298static 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 306void 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("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 329int 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 359size_t persistent_ram_old_size(struct persistent_ram_zone *prz) 360{ 361 return prz->old_log_size; 362} 363 364void *persistent_ram_old(struct persistent_ram_zone *prz) 365{ 366 return prz->old_log; 367} 368 369void 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 376void 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 383static void *persistent_ram_vmap(phys_addr_t start, size_t size, 384 unsigned int memtype) 385{ 386 struct page **pages; 387 phys_addr_t page_start; 388 unsigned int page_count; 389 pgprot_t prot; 390 unsigned int i; 391 void *vaddr; 392 393 page_start = start - offset_in_page(start); 394 page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE); 395 396 if (memtype) 397 prot = pgprot_noncached(PAGE_KERNEL); 398 else 399 prot = pgprot_writecombine(PAGE_KERNEL); 400 401 pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL); 402 if (!pages) { 403 pr_err("%s: Failed to allocate array for %u pages\n", 404 __func__, page_count); 405 return NULL; 406 } 407 408 for (i = 0; i < page_count; i++) { 409 phys_addr_t addr = page_start + i * PAGE_SIZE; 410 pages[i] = pfn_to_page(addr >> PAGE_SHIFT); 411 } 412 vaddr = vmap(pages, page_count, VM_MAP, prot); 413 kfree(pages); 414 415 return vaddr; 416} 417 418static void *persistent_ram_iomap(phys_addr_t start, size_t size, 419 unsigned int memtype) 420{ 421 void *va; 422 423 if (!request_mem_region(start, size, "persistent_ram")) { 424 pr_err("request mem region (0x%llx@0x%llx) failed\n", 425 (unsigned long long)size, (unsigned long long)start); 426 return NULL; 427 } 428 429 buffer_start_add = buffer_start_add_locked; 430 buffer_size_add = buffer_size_add_locked; 431 432 if (memtype) 433 va = ioremap(start, size); 434 else 435 va = ioremap_wc(start, size); 436 437 return va; 438} 439 440static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size, 441 struct persistent_ram_zone *prz, int memtype) 442{ 443 prz->paddr = start; 444 prz->size = size; 445 446 if (pfn_valid(start >> PAGE_SHIFT)) 447 prz->vaddr = persistent_ram_vmap(start, size, memtype); 448 else 449 prz->vaddr = persistent_ram_iomap(start, size, memtype); 450 451 if (!prz->vaddr) { 452 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__, 453 (unsigned long long)size, (unsigned long long)start); 454 return -ENOMEM; 455 } 456 457 prz->buffer = prz->vaddr + offset_in_page(start); 458 prz->buffer_size = size - sizeof(struct persistent_ram_buffer); 459 460 return 0; 461} 462 463static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig, 464 struct persistent_ram_ecc_info *ecc_info) 465{ 466 int ret; 467 468 ret = persistent_ram_init_ecc(prz, ecc_info); 469 if (ret) 470 return ret; 471 472 sig ^= PERSISTENT_RAM_SIG; 473 474 if (prz->buffer->sig == sig) { 475 if (buffer_size(prz) > prz->buffer_size || 476 buffer_start(prz) > buffer_size(prz)) 477 pr_info("found existing invalid buffer, size %zu, start %zu\n", 478 buffer_size(prz), buffer_start(prz)); 479 else { 480 pr_debug("found existing buffer, size %zu, start %zu\n", 481 buffer_size(prz), buffer_start(prz)); 482 persistent_ram_save_old(prz); 483 return 0; 484 } 485 } else { 486 pr_debug("no valid data in buffer (sig = 0x%08x)\n", 487 prz->buffer->sig); 488 } 489 490 prz->buffer->sig = sig; 491 persistent_ram_zap(prz); 492 493 return 0; 494} 495 496void persistent_ram_free(struct persistent_ram_zone *prz) 497{ 498 if (!prz) 499 return; 500 501 if (prz->vaddr) { 502 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) { 503 vunmap(prz->vaddr); 504 } else { 505 iounmap(prz->vaddr); 506 release_mem_region(prz->paddr, prz->size); 507 } 508 prz->vaddr = NULL; 509 } 510 persistent_ram_free_old(prz); 511 kfree(prz); 512} 513 514struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size, 515 u32 sig, struct persistent_ram_ecc_info *ecc_info, 516 unsigned int memtype) 517{ 518 struct persistent_ram_zone *prz; 519 int ret = -ENOMEM; 520 521 prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL); 522 if (!prz) { 523 pr_err("failed to allocate persistent ram zone\n"); 524 goto err; 525 } 526 527 ret = persistent_ram_buffer_map(start, size, prz, memtype); 528 if (ret) 529 goto err; 530 531 ret = persistent_ram_post_init(prz, sig, ecc_info); 532 if (ret) 533 goto err; 534 535 return prz; 536err: 537 persistent_ram_free(prz); 538 return ERR_PTR(ret); 539} 540