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 #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
  31 struct 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
  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 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 */
  67 static 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
  83 static DEFINE_RAW_SPINLOCK(buffer_lock);
  84
  85 /* increase and wrap the start pointer, returning the old value */
  86 static 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 */
 106 static 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
 123 exit:
 124         raw_spin_unlock_irqrestore(&buffer_lock, flags);
 125 }
 126
 127 static size_t (*buffer_start_add)(struct persistent_ram_zone *, size_t) = buffer_start_add_atomic;
 128 static void (*buffer_size_add)(struct persistent_ram_zone *, size_t) = buffer_size_add_atomic;
 129
 130 static 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
 143 static 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
 155 static 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
 181 static 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
 192 static 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
 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("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
 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("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_array(page_count, sizeof(struct page *), GFP_KERNEL);
 398         if (!pages) {
 399                 pr_err("%s: Failed to allocate array for %u pages\n",
 400                        __func__, 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("found existing invalid buffer, size %zu, start %zu\n",
 466                                 buffer_size(prz), buffer_start(prz));
 467                 else {
 468                         pr_debug("found existing buffer, size %zu, start %zu\n",
 469                                  buffer_size(prz), buffer_start(prz));
 470                         persistent_ram_save_old(prz);
 471                         return 0;
 472                 }
 473         } else {
 474                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 475                          prz->buffer->sig);
 476         }
 477
 478         prz->buffer->sig = sig;
 479         persistent_ram_zap(prz);
 480
 481         return 0;
 482 }
 483
 484 void persistent_ram_free(struct persistent_ram_zone *prz)
 485 {
 486         if (!prz)
 487                 return;
 488
 489         if (prz->vaddr) {
 490                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 491                         vunmap(prz->vaddr);
 492                 } else {
 493                         iounmap(prz->vaddr);
 494                         release_mem_region(prz->paddr, prz->size);
 495                 }
 496                 prz->vaddr = NULL;
 497         }
 498         persistent_ram_free_old(prz);
 499         kfree(prz);
 500 }
 501
 502 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 503                         u32 sig, struct persistent_ram_ecc_info *ecc_info)
 504 {
 505         struct persistent_ram_zone *prz;
 506         int ret = -ENOMEM;
 507
 508         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 509         if (!prz) {
 510                 pr_err("failed to allocate persistent ram zone\n");
 511                 goto err;
 512         }
 513
 514         ret = persistent_ram_buffer_map(start, size, prz);
 515         if (ret)
 516                 goto err;
 517
 518         ret = persistent_ram_post_init(prz, sig, ecc_info);
 519         if (ret)
 520                 goto err;
 521
 522         return prz;
 523 err:
 524         persistent_ram_free(prz);
 525         return ERR_PTR(ret);
 526 }