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