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(struct persistent_ram_zone *prz, size_t a)
  52 {
  53         int old;
  54         int new;
  55         unsigned long flags = 0;
  56
  57         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  58                 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
  59
  60         old = atomic_read(&prz->buffer->start);
  61         new = old + a;
  62         while (unlikely(new >= prz->buffer_size))
  63                 new -= prz->buffer_size;
  64         atomic_set(&prz->buffer->start, new);
  65
  66         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  67                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
  68
  69         return old;
  70 }
  71
  72 /* increase the size counter until it hits the max size */
  73 static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
  74 {
  75         size_t old;
  76         size_t new;
  77         unsigned long flags = 0;
  78
  79         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  80                 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
  81
  82         old = atomic_read(&prz->buffer->size);
  83         if (old == prz->buffer_size)
  84                 goto exit;
  85
  86         new = old + a;
  87         if (new > prz->buffer_size)
  88                 new = prz->buffer_size;
  89         atomic_set(&prz->buffer->size, new);
  90
  91 exit:
  92         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  93                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
  94 }
  95
  96 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
  97         uint8_t *data, size_t len, uint8_t *ecc)
  98 {
  99         int i;
 100         uint16_t par[prz->ecc_info.ecc_size];
 101
 102         /* Initialize the parity buffer */
 103         memset(par, 0, sizeof(par));
 104         encode_rs8(prz->rs_decoder, data, len, par, 0);
 105         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 106                 ecc[i] = par[i];
 107 }
 108
 109 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 110         void *data, size_t len, uint8_t *ecc)
 111 {
 112         int i;
 113         uint16_t par[prz->ecc_info.ecc_size];
 114
 115         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 116                 par[i] = ecc[i];
 117         return decode_rs8(prz->rs_decoder, data, par, len,
 118                                 NULL, 0, NULL, 0, NULL);
 119 }
 120
 121 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 122         unsigned int start, unsigned int count)
 123 {
 124         struct persistent_ram_buffer *buffer = prz->buffer;
 125         uint8_t *buffer_end = buffer->data + prz->buffer_size;
 126         uint8_t *block;
 127         uint8_t *par;
 128         int ecc_block_size = prz->ecc_info.block_size;
 129         int ecc_size = prz->ecc_info.ecc_size;
 130         int size = ecc_block_size;
 131
 132         if (!ecc_size)
 133                 return;
 134
 135         block = buffer->data + (start & ~(ecc_block_size - 1));
 136         par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
 137
 138         do {
 139                 if (block + ecc_block_size > buffer_end)
 140                         size = buffer_end - block;
 141                 persistent_ram_encode_rs8(prz, block, size, par);
 142                 block += ecc_block_size;
 143                 par += ecc_size;
 144         } while (block < buffer->data + start + count);
 145 }
 146
 147 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
 148 {
 149         struct persistent_ram_buffer *buffer = prz->buffer;
 150
 151         if (!prz->ecc_info.ecc_size)
 152                 return;
 153
 154         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
 155                                   prz->par_header);
 156 }
 157
 158 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 159 {
 160         struct persistent_ram_buffer *buffer = prz->buffer;
 161         uint8_t *block;
 162         uint8_t *par;
 163
 164         if (!prz->ecc_info.ecc_size)
 165                 return;
 166
 167         block = buffer->data;
 168         par = prz->par_buffer;
 169         while (block < buffer->data + buffer_size(prz)) {
 170                 int numerr;
 171                 int size = prz->ecc_info.block_size;
 172                 if (block + size > buffer->data + prz->buffer_size)
 173                         size = buffer->data + prz->buffer_size - block;
 174                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
 175                 if (numerr > 0) {
 176                         pr_devel("error in block %p, %d\n", block, numerr);
 177                         prz->corrected_bytes += numerr;
 178                 } else if (numerr < 0) {
 179                         pr_devel("uncorrectable error in block %p\n", block);
 180                         prz->bad_blocks++;
 181                 }
 182                 block += prz->ecc_info.block_size;
 183                 par += prz->ecc_info.ecc_size;
 184         }
 185 }
 186
 187 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 188                                    struct persistent_ram_ecc_info *ecc_info)
 189 {
 190         int numerr;
 191         struct persistent_ram_buffer *buffer = prz->buffer;
 192         int ecc_blocks;
 193         size_t ecc_total;
 194
 195         if (!ecc_info || !ecc_info->ecc_size)
 196                 return 0;
 197
 198         prz->ecc_info.block_size = ecc_info->block_size ?: 128;
 199         prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
 200         prz->ecc_info.symsize = ecc_info->symsize ?: 8;
 201         prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
 202
 203         ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
 204                                   prz->ecc_info.block_size +
 205                                   prz->ecc_info.ecc_size);
 206         ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
 207         if (ecc_total >= prz->buffer_size) {
 208                 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
 209                        __func__, prz->ecc_info.ecc_size,
 210                        ecc_total, prz->buffer_size);
 211                 return -EINVAL;
 212         }
 213
 214         prz->buffer_size -= ecc_total;
 215         prz->par_buffer = buffer->data + prz->buffer_size;
 216         prz->par_header = prz->par_buffer +
 217                           ecc_blocks * prz->ecc_info.ecc_size;
 218
 219         /*
 220          * first consecutive root is 0
 221          * primitive element to generate roots = 1
 222          */
 223         prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
 224                                   0, 1, prz->ecc_info.ecc_size);
 225         if (prz->rs_decoder == NULL) {
 226                 pr_info("init_rs failed\n");
 227                 return -EINVAL;
 228         }
 229
 230         prz->corrected_bytes = 0;
 231         prz->bad_blocks = 0;
 232
 233         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 234                                            prz->par_header);
 235         if (numerr > 0) {
 236                 pr_info("error in header, %d\n", numerr);
 237                 prz->corrected_bytes += numerr;
 238         } else if (numerr < 0) {
 239                 pr_info("uncorrectable error in header\n");
 240                 prz->bad_blocks++;
 241         }
 242
 243         return 0;
 244 }
 245
 246 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 247         char *str, size_t len)
 248 {
 249         ssize_t ret;
 250
 251         if (!prz->ecc_info.ecc_size)
 252                 return 0;
 253
 254         if (prz->corrected_bytes || prz->bad_blocks)
 255                 ret = snprintf(str, len, ""
 256                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 257                         prz->corrected_bytes, prz->bad_blocks);
 258         else
 259                 ret = snprintf(str, len, "\nNo errors detected\n");
 260
 261         return ret;
 262 }
 263
 264 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 265         const void *s, unsigned int start, unsigned int count)
 266 {
 267         struct persistent_ram_buffer *buffer = prz->buffer;
 268         memcpy_toio(buffer->data + start, s, count);
 269         persistent_ram_update_ecc(prz, start, count);
 270 }
 271
 272 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 273 {
 274         struct persistent_ram_buffer *buffer = prz->buffer;
 275         size_t size = buffer_size(prz);
 276         size_t start = buffer_start(prz);
 277
 278         if (!size)
 279                 return;
 280
 281         if (!prz->old_log) {
 282                 persistent_ram_ecc_old(prz);
 283                 prz->old_log = kmalloc(size, GFP_KERNEL);
 284         }
 285         if (!prz->old_log) {
 286                 pr_err("failed to allocate buffer\n");
 287                 return;
 288         }
 289
 290         prz->old_log_size = size;
 291         memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
 292         memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
 293 }
 294
 295 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 296         const void *s, unsigned int count)
 297 {
 298         int rem;
 299         int c = count;
 300         size_t start;
 301
 302         if (unlikely(c > prz->buffer_size)) {
 303                 s += c - prz->buffer_size;
 304                 c = prz->buffer_size;
 305         }
 306
 307         buffer_size_add(prz, c);
 308
 309         start = buffer_start_add(prz, c);
 310
 311         rem = prz->buffer_size - start;
 312         if (unlikely(rem < c)) {
 313                 persistent_ram_update(prz, s, start, rem);
 314                 s += rem;
 315                 c -= rem;
 316                 start = 0;
 317         }
 318         persistent_ram_update(prz, s, start, c);
 319
 320         persistent_ram_update_header_ecc(prz);
 321
 322         return count;
 323 }
 324
 325 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 326 {
 327         return prz->old_log_size;
 328 }
 329
 330 void *persistent_ram_old(struct persistent_ram_zone *prz)
 331 {
 332         return prz->old_log;
 333 }
 334
 335 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 336 {
 337         kfree(prz->old_log);
 338         prz->old_log = NULL;
 339         prz->old_log_size = 0;
 340 }
 341
 342 void persistent_ram_zap(struct persistent_ram_zone *prz)
 343 {
 344         atomic_set(&prz->buffer->start, 0);
 345         atomic_set(&prz->buffer->size, 0);
 346         persistent_ram_update_header_ecc(prz);
 347 }
 348
 349 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 350                 unsigned int memtype)
 351 {
 352         struct page **pages;
 353         phys_addr_t page_start;
 354         unsigned int page_count;
 355         pgprot_t prot;
 356         unsigned int i;
 357         void *vaddr;
 358
 359         page_start = start - offset_in_page(start);
 360         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 361
 362         if (memtype)
 363                 prot = pgprot_noncached(PAGE_KERNEL);
 364         else
 365                 prot = pgprot_writecombine(PAGE_KERNEL);
 366
 367         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
 368         if (!pages) {
 369                 pr_err("%s: Failed to allocate array for %u pages\n",
 370                        __func__, page_count);
 371                 return NULL;
 372         }
 373
 374         for (i = 0; i < page_count; i++) {
 375                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 376                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 377         }
 378         vaddr = vmap(pages, page_count, VM_MAP, prot);
 379         kfree(pages);
 380
 381         return vaddr;
 382 }
 383
 384 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
 385                 unsigned int memtype)
 386 {
 387         void *va;
 388
 389         if (!request_mem_region(start, size, "persistent_ram")) {
 390                 pr_err("request mem region (0x%llx@0x%llx) failed\n",
 391                         (unsigned long long)size, (unsigned long long)start);
 392                 return NULL;
 393         }
 394
 395         if (memtype)
 396                 va = ioremap(start, size);
 397         else
 398                 va = ioremap_wc(start, size);
 399
 400         return va;
 401 }
 402
 403 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 404                 struct persistent_ram_zone *prz, int memtype)
 405 {
 406         prz->paddr = start;
 407         prz->size = size;
 408
 409         if (pfn_valid(start >> PAGE_SHIFT))
 410                 prz->vaddr = persistent_ram_vmap(start, size, memtype);
 411         else
 412                 prz->vaddr = persistent_ram_iomap(start, size, memtype);
 413
 414         if (!prz->vaddr) {
 415                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 416                         (unsigned long long)size, (unsigned long long)start);
 417                 return -ENOMEM;
 418         }
 419
 420         prz->buffer = prz->vaddr + offset_in_page(start);
 421         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 422
 423         return 0;
 424 }
 425
 426 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 427                                     struct persistent_ram_ecc_info *ecc_info)
 428 {
 429         int ret;
 430
 431         ret = persistent_ram_init_ecc(prz, ecc_info);
 432         if (ret)
 433                 return ret;
 434
 435         sig ^= PERSISTENT_RAM_SIG;
 436
 437         if (prz->buffer->sig == sig) {
 438                 if (buffer_size(prz) > prz->buffer_size ||
 439                     buffer_start(prz) > buffer_size(prz))
 440                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
 441                                 buffer_size(prz), buffer_start(prz));
 442                 else {
 443                         pr_debug("found existing buffer, size %zu, start %zu\n",
 444                                  buffer_size(prz), buffer_start(prz));
 445                         persistent_ram_save_old(prz);
 446                         return 0;
 447                 }
 448         } else {
 449                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 450                          prz->buffer->sig);
 451         }
 452
 453         /* Rewind missing or invalid memory area. */
 454         prz->buffer->sig = sig;
 455         persistent_ram_zap(prz);
 456
 457         return 0;
 458 }
 459
 460 void persistent_ram_free(struct persistent_ram_zone *prz)
 461 {
 462         if (!prz)
 463                 return;
 464
 465         if (prz->vaddr) {
 466                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 467                         vunmap(prz->vaddr);
 468                 } else {
 469                         iounmap(prz->vaddr);
 470                         release_mem_region(prz->paddr, prz->size);
 471                 }
 472                 prz->vaddr = NULL;
 473         }
 474         persistent_ram_free_old(prz);
 475         kfree(prz);
 476 }
 477
 478 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 479                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
 480                         unsigned int memtype, u32 flags)
 481 {
 482         struct persistent_ram_zone *prz;
 483         int ret = -ENOMEM;
 484
 485         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 486         if (!prz) {
 487                 pr_err("failed to allocate persistent ram zone\n");
 488                 goto err;
 489         }
 490
 491         /* Initialize general buffer state. */
 492         raw_spin_lock_init(&prz->buffer_lock);
 493         prz->flags = flags;
 494
 495         ret = persistent_ram_buffer_map(start, size, prz, memtype);
 496         if (ret)
 497                 goto err;
 498
 499         ret = persistent_ram_post_init(prz, sig, ecc_info);
 500         if (ret)
 501                 goto err;
 502
 503         return prz;
 504 err:
 505         persistent_ram_free(prz);
 506         return ERR_PTR(ret);
 507 }