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_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_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_size];
  99
 100         for (i = 0; i < prz->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_block_size;
 114         int ecc_size = prz->ecc_size;
 115         int size = prz->ecc_block_size;
 116
 117         if (!prz->ecc_size)
 118                 return;
 119
 120         block = buffer->data + (start & ~(ecc_block_size - 1));
 121         par = prz->par_buffer + (start / ecc_block_size) * prz->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_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_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_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_block_size;
 170                 par += prz->ecc_size;
 171         }
 172 }
 173
 174 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 175                                    int ecc_size)
 176 {
 177         int numerr;
 178         struct persistent_ram_buffer *buffer = prz->buffer;
 179         int ecc_blocks;
 180         size_t ecc_total;
 181         int ecc_symsize = 8;
 182         int ecc_poly = 0x11d;
 183
 184         if (!ecc_size)
 185                 return 0;
 186
 187         prz->ecc_block_size = 128;
 188         prz->ecc_size = ecc_size;
 189
 190         ecc_blocks = DIV_ROUND_UP(prz->buffer_size, prz->ecc_block_size);
 191         ecc_total = (ecc_blocks + 1) * prz->ecc_size;
 192         if (ecc_total >= prz->buffer_size) {
 193                 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
 194                        __func__, prz->ecc_size, ecc_total, prz->buffer_size);
 195                 return -EINVAL;
 196         }
 197
 198         prz->buffer_size -= ecc_total;
 199         prz->par_buffer = buffer->data + prz->buffer_size;
 200         prz->par_header = prz->par_buffer + ecc_blocks * prz->ecc_size;
 201
 202         /*
 203          * first consecutive root is 0
 204          * primitive element to generate roots = 1
 205          */
 206         prz->rs_decoder = init_rs(ecc_symsize, ecc_poly, 0, 1, prz->ecc_size);
 207         if (prz->rs_decoder == NULL) {
 208                 pr_info("persistent_ram: init_rs failed\n");
 209                 return -EINVAL;
 210         }
 211
 212         prz->corrected_bytes = 0;
 213         prz->bad_blocks = 0;
 214
 215         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 216                                            prz->par_header);
 217         if (numerr > 0) {
 218                 pr_info("persistent_ram: error in header, %d\n", numerr);
 219                 prz->corrected_bytes += numerr;
 220         } else if (numerr < 0) {
 221                 pr_info("persistent_ram: uncorrectable error in header\n");
 222                 prz->bad_blocks++;
 223         }
 224
 225         return 0;
 226 }
 227
 228 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 229         char *str, size_t len)
 230 {
 231         ssize_t ret;
 232
 233         if (prz->corrected_bytes || prz->bad_blocks)
 234                 ret = snprintf(str, len, ""
 235                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 236                         prz->corrected_bytes, prz->bad_blocks);
 237         else
 238                 ret = snprintf(str, len, "\nNo errors detected\n");
 239
 240         return ret;
 241 }
 242
 243 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 244         const void *s, unsigned int start, unsigned int count)
 245 {
 246         struct persistent_ram_buffer *buffer = prz->buffer;
 247         memcpy(buffer->data + start, s, count);
 248         persistent_ram_update_ecc(prz, start, count);
 249 }
 250
 251 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 252 {
 253         struct persistent_ram_buffer *buffer = prz->buffer;
 254         size_t size = buffer_size(prz);
 255         size_t start = buffer_start(prz);
 256
 257         if (!size)
 258                 return;
 259
 260         if (!prz->old_log) {
 261                 persistent_ram_ecc_old(prz);
 262                 prz->old_log = kmalloc(size, GFP_KERNEL);
 263         }
 264         if (!prz->old_log) {
 265                 pr_err("persistent_ram: failed to allocate buffer\n");
 266                 return;
 267         }
 268
 269         prz->old_log_size = size;
 270         memcpy(prz->old_log, &buffer->data[start], size - start);
 271         memcpy(prz->old_log + size - start, &buffer->data[0], start);
 272 }
 273
 274 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 275         const void *s, unsigned int count)
 276 {
 277         int rem;
 278         int c = count;
 279         size_t start;
 280
 281         if (unlikely(c > prz->buffer_size)) {
 282                 s += c - prz->buffer_size;
 283                 c = prz->buffer_size;
 284         }
 285
 286         buffer_size_add(prz, c);
 287
 288         start = buffer_start_add(prz, c);
 289
 290         rem = prz->buffer_size - start;
 291         if (unlikely(rem < c)) {
 292                 persistent_ram_update(prz, s, start, rem);
 293                 s += rem;
 294                 c -= rem;
 295                 start = 0;
 296         }
 297         persistent_ram_update(prz, s, start, c);
 298
 299         persistent_ram_update_header_ecc(prz);
 300
 301         return count;
 302 }
 303
 304 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 305 {
 306         return prz->old_log_size;
 307 }
 308
 309 void *persistent_ram_old(struct persistent_ram_zone *prz)
 310 {
 311         return prz->old_log;
 312 }
 313
 314 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 315 {
 316         kfree(prz->old_log);
 317         prz->old_log = NULL;
 318         prz->old_log_size = 0;
 319 }
 320
 321 void persistent_ram_zap(struct persistent_ram_zone *prz)
 322 {
 323         atomic_set(&prz->buffer->start, 0);
 324         atomic_set(&prz->buffer->size, 0);
 325         persistent_ram_update_header_ecc(prz);
 326 }
 327
 328 static void *persistent_ram_vmap(phys_addr_t start, size_t size)
 329 {
 330         struct page **pages;
 331         phys_addr_t page_start;
 332         unsigned int page_count;
 333         pgprot_t prot;
 334         unsigned int i;
 335         void *vaddr;
 336
 337         page_start = start - offset_in_page(start);
 338         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 339
 340         prot = pgprot_noncached(PAGE_KERNEL);
 341
 342         pages = kmalloc(sizeof(struct page *) * page_count, GFP_KERNEL);
 343         if (!pages) {
 344                 pr_err("%s: Failed to allocate array for %u pages\n", __func__,
 345                         page_count);
 346                 return NULL;
 347         }
 348
 349         for (i = 0; i < page_count; i++) {
 350                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 351                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 352         }
 353         vaddr = vmap(pages, page_count, VM_MAP, prot);
 354         kfree(pages);
 355
 356         return vaddr;
 357 }
 358
 359 static void *persistent_ram_iomap(phys_addr_t start, size_t size)
 360 {
 361         if (!request_mem_region(start, size, "persistent_ram")) {
 362                 pr_err("request mem region (0x%llx@0x%llx) failed\n",
 363                         (unsigned long long)size, (unsigned long long)start);
 364                 return NULL;
 365         }
 366
 367         return ioremap(start, size);
 368 }
 369
 370 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 371                 struct persistent_ram_zone *prz)
 372 {
 373         prz->paddr = start;
 374         prz->size = size;
 375
 376         if (pfn_valid(start >> PAGE_SHIFT))
 377                 prz->vaddr = persistent_ram_vmap(start, size);
 378         else
 379                 prz->vaddr = persistent_ram_iomap(start, size);
 380
 381         if (!prz->vaddr) {
 382                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 383                         (unsigned long long)size, (unsigned long long)start);
 384                 return -ENOMEM;
 385         }
 386
 387         prz->buffer = prz->vaddr + offset_in_page(start);
 388         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 389
 390         return 0;
 391 }
 392
 393 static int __devinit persistent_ram_post_init(struct persistent_ram_zone *prz,
 394                                               u32 sig, int ecc_size)
 395 {
 396         int ret;
 397
 398         ret = persistent_ram_init_ecc(prz, ecc_size);
 399         if (ret)
 400                 return ret;
 401
 402         sig ^= PERSISTENT_RAM_SIG;
 403
 404         if (prz->buffer->sig == sig) {
 405                 if (buffer_size(prz) > prz->buffer_size ||
 406                     buffer_start(prz) > buffer_size(prz))
 407                         pr_info("persistent_ram: found existing invalid buffer,"
 408                                 " size %zu, start %zu\n",
 409                                buffer_size(prz), buffer_start(prz));
 410                 else {
 411                         pr_debug("persistent_ram: found existing buffer,"
 412                                 " size %zu, start %zu\n",
 413                                buffer_size(prz), buffer_start(prz));
 414                         persistent_ram_save_old(prz);
 415                         return 0;
 416                 }
 417         } else {
 418                 pr_debug("persistent_ram: no valid data in buffer"
 419                         " (sig = 0x%08x)\n", prz->buffer->sig);
 420         }
 421
 422         prz->buffer->sig = sig;
 423         persistent_ram_zap(prz);
 424
 425         return 0;
 426 }
 427
 428 void persistent_ram_free(struct persistent_ram_zone *prz)
 429 {
 430         if (!prz)
 431                 return;
 432
 433         if (prz->vaddr) {
 434                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 435                         vunmap(prz->vaddr);
 436                 } else {
 437                         iounmap(prz->vaddr);
 438                         release_mem_region(prz->paddr, prz->size);
 439                 }
 440                 prz->vaddr = NULL;
 441         }
 442         persistent_ram_free_old(prz);
 443         kfree(prz);
 444 }
 445
 446 struct persistent_ram_zone * __devinit persistent_ram_new(phys_addr_t start,
 447                                                           size_t size, u32 sig,
 448                                                           int ecc_size)
 449 {
 450         struct persistent_ram_zone *prz;
 451         int ret = -ENOMEM;
 452
 453         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 454         if (!prz) {
 455                 pr_err("persistent_ram: failed to allocate persistent ram zone\n");
 456                 goto err;
 457         }
 458
 459         ret = persistent_ram_buffer_map(start, size, prz);
 460         if (ret)
 461                 goto err;
 462
 463         ret = persistent_ram_post_init(prz, sig, ecc_size);
 464         if (ret)
 465                 goto err;
 466
 467         return prz;
 468 err:
 469         persistent_ram_free(prz);
 470         return ERR_PTR(ret);
 471 }