fs/pstore/ram_core.c

   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 __initdata LIST_HEAD(persistent_ram_list);
  39
  40 static inline size_t buffer_size(struct persistent_ram_zone *prz)
  41 {
  42         return atomic_read(&prz->buffer->size);
  43 }
  44
  45 static 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 */
  51 static inline size_t buffer_start_add(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 */
  67 static inline void buffer_size_add(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
  83 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
  84         uint8_t *data, size_t len, uint8_t *ecc)
  85 {
  86         int i;
  87         uint16_t par[prz->ecc_size];
  88
  89         /* Initialize the parity buffer */
  90         memset(par, 0, sizeof(par));
  91         encode_rs8(prz->rs_decoder, data, len, par, 0);
  92         for (i = 0; i < prz->ecc_size; i++)
  93                 ecc[i] = par[i];
  94 }
  95
  96 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
  97         void *data, size_t len, uint8_t *ecc)
  98 {
  99         int i;
 100         uint16_t par[prz->ecc_size];
 101
 102         for (i = 0; i < prz->ecc_size; i++)
 103                 par[i] = ecc[i];
 104         return decode_rs8(prz->rs_decoder, data, par, len,
 105                                 NULL, 0, NULL, 0, NULL);
 106 }
 107
 108 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 109         unsigned int start, unsigned int count)
 110 {
 111         struct persistent_ram_buffer *buffer = prz->buffer;
 112         uint8_t *buffer_end = buffer->data + prz->buffer_size;
 113         uint8_t *block;
 114         uint8_t *par;
 115         int ecc_block_size = prz->ecc_block_size;
 116         int ecc_size = prz->ecc_size;
 117         int size = prz->ecc_block_size;
 118
 119         if (!prz->ecc)
 120                 return;
 121
 122         block = buffer->data + (start & ~(ecc_block_size - 1));
 123         par = prz->par_buffer + (start / ecc_block_size) * prz->ecc_size;
 124
 125         do {
 126                 if (block + ecc_block_size > buffer_end)
 127                         size = buffer_end - block;
 128                 persistent_ram_encode_rs8(prz, block, size, par);
 129                 block += ecc_block_size;
 130                 par += ecc_size;
 131         } while (block < buffer->data + start + count);
 132 }
 133
 134 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
 135 {
 136         struct persistent_ram_buffer *buffer = prz->buffer;
 137
 138         if (!prz->ecc)
 139                 return;
 140
 141         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
 142                                   prz->par_header);
 143 }
 144
 145 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 146 {
 147         struct persistent_ram_buffer *buffer = prz->buffer;
 148         uint8_t *block;
 149         uint8_t *par;
 150
 151         if (!prz->ecc)
 152                 return;
 153
 154         block = buffer->data;
 155         par = prz->par_buffer;
 156         while (block < buffer->data + buffer_size(prz)) {
 157                 int numerr;
 158                 int size = prz->ecc_block_size;
 159                 if (block + size > buffer->data + prz->buffer_size)
 160                         size = buffer->data + prz->buffer_size - block;
 161                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
 162                 if (numerr > 0) {
 163                         pr_devel("persistent_ram: error in block %p, %d\n",
 164                                block, numerr);
 165                         prz->corrected_bytes += numerr;
 166                 } else if (numerr < 0) {
 167                         pr_devel("persistent_ram: uncorrectable error in block %p\n",
 168                                 block);
 169                         prz->bad_blocks++;
 170                 }
 171                 block += prz->ecc_block_size;
 172                 par += prz->ecc_size;
 173         }
 174 }
 175
 176 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 177         size_t buffer_size)
 178 {
 179         int numerr;
 180         struct persistent_ram_buffer *buffer = prz->buffer;
 181         int ecc_blocks;
 182
 183         if (!prz->ecc)
 184                 return 0;
 185
 186         prz->ecc_block_size = 128;
 187         prz->ecc_size = 16;
 188         prz->ecc_symsize = 8;
 189         prz->ecc_poly = 0x11d;
 190
 191         ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
 192         prz->buffer_size -= (ecc_blocks + 1) * prz->ecc_size;
 193
 194         if (prz->buffer_size > buffer_size) {
 195                 pr_err("persistent_ram: invalid size %zu, non-ecc datasize %zu\n",
 196                        buffer_size, prz->buffer_size);
 197                 return -EINVAL;
 198         }
 199
 200         prz->par_buffer = buffer->data + prz->buffer_size;
 201         prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
 202
 203         /*
 204          * first consecutive root is 0
 205          * primitive element to generate roots = 1
 206          */
 207         prz->rs_decoder = init_rs(prz->ecc_symsize, prz->ecc_poly, 0, 1,
 208                                   prz->ecc_size);
 209         if (prz->rs_decoder == NULL) {
 210                 pr_info("persistent_ram: init_rs failed\n");
 211                 return -EINVAL;
 212         }
 213
 214         prz->corrected_bytes = 0;
 215         prz->bad_blocks = 0;
 216
 217         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 218                                            prz->par_header);
 219         if (numerr > 0) {
 220                 pr_info("persistent_ram: error in header, %d\n", numerr);
 221                 prz->corrected_bytes += numerr;
 222         } else if (numerr < 0) {
 223                 pr_info("persistent_ram: uncorrectable error in header\n");
 224                 prz->bad_blocks++;
 225         }
 226
 227         return 0;
 228 }
 229
 230 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 231         char *str, size_t len)
 232 {
 233         ssize_t ret;
 234
 235         if (prz->corrected_bytes || prz->bad_blocks)
 236                 ret = snprintf(str, len, ""
 237                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 238                         prz->corrected_bytes, prz->bad_blocks);
 239         else
 240                 ret = snprintf(str, len, "\nNo errors detected\n");
 241
 242         return ret;
 243 }
 244
 245 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 246         const void *s, unsigned int start, unsigned int count)
 247 {
 248         struct persistent_ram_buffer *buffer = prz->buffer;
 249         memcpy(buffer->data + start, s, count);
 250         persistent_ram_update_ecc(prz, start, count);
 251 }
 252
 253 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 254 {
 255         struct persistent_ram_buffer *buffer = prz->buffer;
 256         size_t size = buffer_size(prz);
 257         size_t start = buffer_start(prz);
 258
 259         if (!size)
 260                 return;
 261
 262         if (!prz->old_log) {
 263                 persistent_ram_ecc_old(prz);
 264                 prz->old_log = kmalloc(size, GFP_KERNEL);
 265         }
 266         if (!prz->old_log) {
 267                 pr_err("persistent_ram: failed to allocate buffer\n");
 268                 return;
 269         }
 270
 271         prz->old_log_size = size;
 272         memcpy(prz->old_log, &buffer->data[start], size - start);
 273         memcpy(prz->old_log + size - start, &buffer->data[0], start);
 274 }
 275
 276 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 277         const void *s, unsigned int count)
 278 {
 279         int rem;
 280         int c = count;
 281         size_t start;
 282
 283         if (unlikely(c > prz->buffer_size)) {
 284                 s += c - prz->buffer_size;
 285                 c = prz->buffer_size;
 286         }
 287
 288         buffer_size_add(prz, c);
 289
 290         start = buffer_start_add(prz, c);
 291
 292         rem = prz->buffer_size - start;
 293         if (unlikely(rem < c)) {
 294                 persistent_ram_update(prz, s, start, rem);
 295                 s += rem;
 296                 c -= rem;
 297                 start = 0;
 298         }
 299         persistent_ram_update(prz, s, start, c);
 300
 301         persistent_ram_update_header_ecc(prz);
 302
 303         return count;
 304 }
 305
 306 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 307 {
 308         return prz->old_log_size;
 309 }
 310
 311 void *persistent_ram_old(struct persistent_ram_zone *prz)
 312 {
 313         return prz->old_log;
 314 }
 315
 316 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 317 {
 318         kfree(prz->old_log);
 319         prz->old_log = NULL;
 320         prz->old_log_size = 0;
 321 }
 322
 323 void persistent_ram_zap(struct persistent_ram_zone *prz)
 324 {
 325         atomic_set(&prz->buffer->start, 0);
 326         atomic_set(&prz->buffer->size, 0);
 327         persistent_ram_update_header_ecc(prz);
 328 }
 329
 330 static void *persistent_ram_vmap(phys_addr_t start, size_t size)
 331 {
 332         struct page **pages;
 333         phys_addr_t page_start;
 334         unsigned int page_count;
 335         pgprot_t prot;
 336         unsigned int i;
 337         void *vaddr;
 338
 339         page_start = start - offset_in_page(start);
 340         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 341
 342         prot = pgprot_noncached(PAGE_KERNEL);
 343
 344         pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
 345         if (!pages) {
 346                 pr_err("%s: Failed to allocate array for %u pages\n", __func__,
 347                         page_count);
 348                 return NULL;
 349         }
 350
 351         for (i = 0; i < page_count; i++) {
 352                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 353                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 354         }
 355         vaddr = vmap(pages, page_count, VM_MAP, prot);
 356         kfree(pages);
 357
 358         return vaddr;
 359 }
 360
 361 static void *persistent_ram_iomap(phys_addr_t start, size_t size)
 362 {
 363         if (!request_mem_region(start, size, "persistent_ram")) {
 364                 pr_err("request mem region (0x%llx@0x%llx) failed\n",
 365                         (unsigned long long)size, (unsigned long long)start);
 366                 return NULL;
 367         }
 368
 369         return ioremap(start, size);
 370 }
 371
 372 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 373                 struct persistent_ram_zone *prz)
 374 {
 375         prz->paddr = start;
 376         prz->size = size;
 377
 378         if (pfn_valid(start >> PAGE_SHIFT))
 379                 prz->vaddr = persistent_ram_vmap(start, size);
 380         else
 381                 prz->vaddr = persistent_ram_iomap(start, size);
 382
 383         if (!prz->vaddr) {
 384                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 385                         (unsigned long long)size, (unsigned long long)start);
 386                 return -ENOMEM;
 387         }
 388
 389         prz->buffer = prz->vaddr + offset_in_page(start);
 390         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 391
 392         return 0;
 393 }
 394
 395 static int __init persistent_ram_post_init(struct persistent_ram_zone *prz, bool ecc)
 396 {
 397         int ret;
 398
 399         prz->ecc = ecc;
 400
 401         ret = persistent_ram_init_ecc(prz, prz->buffer_size);
 402         if (ret)
 403                 return ret;
 404
 405         if (prz->buffer->sig == PERSISTENT_RAM_SIG) {
 406                 if (buffer_size(prz) > prz->buffer_size ||
 407                     buffer_start(prz) > buffer_size(prz))
 408                         pr_info("persistent_ram: found existing invalid buffer,"
 409                                 " size %zu, start %zu\n",
 410                                buffer_size(prz), buffer_start(prz));
 411                 else {
 412                         pr_info("persistent_ram: found existing buffer,"
 413                                 " size %zu, start %zu\n",
 414                                buffer_size(prz), buffer_start(prz));
 415                         persistent_ram_save_old(prz);
 416                         return 0;
 417                 }
 418         } else {
 419                 pr_info("persistent_ram: no valid data in buffer"
 420                         " (sig = 0x%08x)\n", prz->buffer->sig);
 421         }
 422
 423         prz->buffer->sig = PERSISTENT_RAM_SIG;
 424         persistent_ram_zap(prz);
 425
 426         return 0;
 427 }
 428
 429 void persistent_ram_free(struct persistent_ram_zone *prz)
 430 {
 431         if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 432                 vunmap(prz->vaddr);
 433         } else {
 434                 iounmap(prz->vaddr);
 435                 release_mem_region(prz->paddr, prz->size);
 436         }
 437         persistent_ram_free_old(prz);
 438         kfree(prz);
 439 }
 440
 441 struct persistent_ram_zone * __init persistent_ram_new(phys_addr_t start,
 442                                                        size_t size,
 443                                                        bool ecc)
 444 {
 445         struct persistent_ram_zone *prz;
 446         int ret = -ENOMEM;
 447
 448         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 449         if (!prz) {
 450                 pr_err("persistent_ram: failed to allocate persistent ram zone\n");
 451                 goto err;
 452         }
 453
 454         ret = persistent_ram_buffer_map(start, size, prz);
 455         if (ret)
 456                 goto err;
 457
 458         persistent_ram_post_init(prz, ecc);
 459
 460         return prz;
 461 err:
 462         kfree(prz);
 463         return ERR_PTR(ret);
 464 }
 465
 466 #ifndef MODULE
 467 static int __init persistent_ram_buffer_init(const char *name,
 468                 struct persistent_ram_zone *prz)
 469 {
 470         int i;
 471         struct persistent_ram *ram;
 472         struct persistent_ram_descriptor *desc;
 473         phys_addr_t start;
 474
 475         list_for_each_entry(ram, &persistent_ram_list, node) {
 476                 start = ram->start;
 477                 for (i = 0; i < ram->num_descs; i++) {
 478                         desc = &ram->descs[i];
 479                         if (!strcmp(desc->name, name))
 480                                 return persistent_ram_buffer_map(start,
 481                                                 desc->size, prz);
 482                         start += desc->size;
 483                 }
 484         }
 485
 486         return -EINVAL;
 487 }
 488
 489 static  __init
 490 struct persistent_ram_zone *__persistent_ram_init(struct device *dev, bool ecc)
 491 {
 492         struct persistent_ram_zone *prz;
 493         int ret = -ENOMEM;
 494
 495         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 496         if (!prz) {
 497                 pr_err("persistent_ram: failed to allocate persistent ram zone\n");
 498                 goto err;
 499         }
 500
 501         ret = persistent_ram_buffer_init(dev_name(dev), prz);
 502         if (ret) {
 503                 pr_err("persistent_ram: failed to initialize buffer\n");
 504                 goto err;
 505         }
 506
 507         persistent_ram_post_init(prz, ecc);
 508
 509         return prz;
 510 err:
 511         kfree(prz);
 512         return ERR_PTR(ret);
 513 }
 514
 515 struct persistent_ram_zone * __init
 516 persistent_ram_init_ringbuffer(struct device *dev, bool ecc)
 517 {
 518         return __persistent_ram_init(dev, ecc);
 519 }
 520
 521 int __init persistent_ram_early_init(struct persistent_ram *ram)
 522 {
 523         int ret;
 524
 525         ret = memblock_reserve(ram->start, ram->size);
 526         if (ret) {
 527                 pr_err("Failed to reserve persistent memory from %08lx-%08lx\n",
 528                         (long)ram->start, (long)(ram->start + ram->size - 1));
 529                 return ret;
 530         }
 531
 532         list_add_tail(&ram->node, &persistent_ram_list);
 533
 534         pr_info("Initialized persistent memory from %08lx-%08lx\n",
 535                 (long)ram->start, (long)(ram->start + ram->size - 1));
 536
 537         return 0;
 538 }
 539 #endif