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/init.h>
  21 #include <linux/io.h>
  22 #include <linux/kernel.h>
  23 #include <linux/list.h>
  24 #include <linux/memblock.h>
  25 #include <linux/pstore_ram.h>
  26 #include <linux/rslib.h>
  27 #include <linux/slab.h>
  28 #include <linux/uaccess.h>
  29 #include <linux/vmalloc.h>
  30 #include <asm/page.h>
  31
  32 struct persistent_ram_buffer {
  33         uint32_t    sig;
  34         atomic_t    start;
  35         atomic_t    size;
  36         uint8_t     data[0];
  37 };
  38
  39 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
  40
  41 static inline size_t buffer_size(struct persistent_ram_zone *prz)
  42 {
  43         return atomic_read(&prz->buffer->size);
  44 }
  45
  46 static inline size_t buffer_start(struct persistent_ram_zone *prz)
  47 {
  48         return atomic_read(&prz->buffer->start);
  49 }
  50
  51 /* increase and wrap the start pointer, returning the old value */
  52 static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
  53 {
  54         int old;
  55         int new;
  56         unsigned long flags = 0;
  57
  58         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  59                 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
  60
  61         old = atomic_read(&prz->buffer->start);
  62         new = old + a;
  63         while (unlikely(new >= prz->buffer_size))
  64                 new -= prz->buffer_size;
  65         atomic_set(&prz->buffer->start, new);
  66
  67         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  68                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
  69
  70         return old;
  71 }
  72
  73 /* increase the size counter until it hits the max size */
  74 static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
  75 {
  76         size_t old;
  77         size_t new;
  78         unsigned long flags = 0;
  79
  80         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  81                 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
  82
  83         old = atomic_read(&prz->buffer->size);
  84         if (old == prz->buffer_size)
  85                 goto exit;
  86
  87         new = old + a;
  88         if (new > prz->buffer_size)
  89                 new = prz->buffer_size;
  90         atomic_set(&prz->buffer->size, new);
  91
  92 exit:
  93         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  94                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
  95 }
  96
  97 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
  98         uint8_t *data, size_t len, uint8_t *ecc)
  99 {
 100         int i;
 101
 102         /* Initialize the parity buffer */
 103         memset(prz->ecc_info.par, 0,
 104                prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
 105         encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
 106         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 107                 ecc[i] = prz->ecc_info.par[i];
 108 }
 109
 110 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 111         void *data, size_t len, uint8_t *ecc)
 112 {
 113         int i;
 114
 115         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 116                 prz->ecc_info.par[i] = ecc[i];
 117         return decode_rs8(prz->rs_decoder, data, prz->ecc_info.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         /* allocate workspace instead of using stack VLA */
 231         prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
 232                                           sizeof(*prz->ecc_info.par),
 233                                           GFP_KERNEL);
 234         if (!prz->ecc_info.par) {
 235                 pr_err("cannot allocate ECC parity workspace\n");
 236                 return -ENOMEM;
 237         }
 238
 239         prz->corrected_bytes = 0;
 240         prz->bad_blocks = 0;
 241
 242         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 243                                            prz->par_header);
 244         if (numerr > 0) {
 245                 pr_info("error in header, %d\n", numerr);
 246                 prz->corrected_bytes += numerr;
 247         } else if (numerr < 0) {
 248                 pr_info("uncorrectable error in header\n");
 249                 prz->bad_blocks++;
 250         }
 251
 252         return 0;
 253 }
 254
 255 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 256         char *str, size_t len)
 257 {
 258         ssize_t ret;
 259
 260         if (!prz->ecc_info.ecc_size)
 261                 return 0;
 262
 263         if (prz->corrected_bytes || prz->bad_blocks)
 264                 ret = snprintf(str, len, ""
 265                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 266                         prz->corrected_bytes, prz->bad_blocks);
 267         else
 268                 ret = snprintf(str, len, "\nNo errors detected\n");
 269
 270         return ret;
 271 }
 272
 273 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 274         const void *s, unsigned int start, unsigned int count)
 275 {
 276         struct persistent_ram_buffer *buffer = prz->buffer;
 277         memcpy_toio(buffer->data + start, s, count);
 278         persistent_ram_update_ecc(prz, start, count);
 279 }
 280
 281 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
 282         const void __user *s, unsigned int start, unsigned int count)
 283 {
 284         struct persistent_ram_buffer *buffer = prz->buffer;
 285         int ret = unlikely(__copy_from_user(buffer->data + start, s, count)) ?
 286                 -EFAULT : 0;
 287         persistent_ram_update_ecc(prz, start, count);
 288         return ret;
 289 }
 290
 291 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 292 {
 293         struct persistent_ram_buffer *buffer = prz->buffer;
 294         size_t size = buffer_size(prz);
 295         size_t start = buffer_start(prz);
 296
 297         if (!size)
 298                 return;
 299
 300         if (!prz->old_log) {
 301                 persistent_ram_ecc_old(prz);
 302                 prz->old_log = kmalloc(size, GFP_KERNEL);
 303         }
 304         if (!prz->old_log) {
 305                 pr_err("failed to allocate buffer\n");
 306                 return;
 307         }
 308
 309         prz->old_log_size = size;
 310         memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
 311         memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
 312 }
 313
 314 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 315         const void *s, unsigned int count)
 316 {
 317         int rem;
 318         int c = count;
 319         size_t start;
 320
 321         if (unlikely(c > prz->buffer_size)) {
 322                 s += c - prz->buffer_size;
 323                 c = prz->buffer_size;
 324         }
 325
 326         buffer_size_add(prz, c);
 327
 328         start = buffer_start_add(prz, c);
 329
 330         rem = prz->buffer_size - start;
 331         if (unlikely(rem < c)) {
 332                 persistent_ram_update(prz, s, start, rem);
 333                 s += rem;
 334                 c -= rem;
 335                 start = 0;
 336         }
 337         persistent_ram_update(prz, s, start, c);
 338
 339         persistent_ram_update_header_ecc(prz);
 340
 341         return count;
 342 }
 343
 344 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
 345         const void __user *s, unsigned int count)
 346 {
 347         int rem, ret = 0, c = count;
 348         size_t start;
 349
 350         if (unlikely(!access_ok(VERIFY_READ, s, count)))
 351                 return -EFAULT;
 352         if (unlikely(c > prz->buffer_size)) {
 353                 s += c - prz->buffer_size;
 354                 c = prz->buffer_size;
 355         }
 356
 357         buffer_size_add(prz, c);
 358
 359         start = buffer_start_add(prz, c);
 360
 361         rem = prz->buffer_size - start;
 362         if (unlikely(rem < c)) {
 363                 ret = persistent_ram_update_user(prz, s, start, rem);
 364                 s += rem;
 365                 c -= rem;
 366                 start = 0;
 367         }
 368         if (likely(!ret))
 369                 ret = persistent_ram_update_user(prz, s, start, c);
 370
 371         persistent_ram_update_header_ecc(prz);
 372
 373         return unlikely(ret) ? ret : count;
 374 }
 375
 376 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 377 {
 378         return prz->old_log_size;
 379 }
 380
 381 void *persistent_ram_old(struct persistent_ram_zone *prz)
 382 {
 383         return prz->old_log;
 384 }
 385
 386 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 387 {
 388         kfree(prz->old_log);
 389         prz->old_log = NULL;
 390         prz->old_log_size = 0;
 391 }
 392
 393 void persistent_ram_zap(struct persistent_ram_zone *prz)
 394 {
 395         atomic_set(&prz->buffer->start, 0);
 396         atomic_set(&prz->buffer->size, 0);
 397         persistent_ram_update_header_ecc(prz);
 398 }
 399
 400 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 401                 unsigned int memtype)
 402 {
 403         struct page **pages;
 404         phys_addr_t page_start;
 405         unsigned int page_count;
 406         pgprot_t prot;
 407         unsigned int i;
 408         void *vaddr;
 409
 410         page_start = start - offset_in_page(start);
 411         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 412
 413         if (memtype)
 414                 prot = pgprot_noncached(PAGE_KERNEL);
 415         else
 416                 prot = pgprot_writecombine(PAGE_KERNEL);
 417
 418         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
 419         if (!pages) {
 420                 pr_err("%s: Failed to allocate array for %u pages\n",
 421                        __func__, page_count);
 422                 return NULL;
 423         }
 424
 425         for (i = 0; i < page_count; i++) {
 426                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 427                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 428         }
 429         vaddr = vmap(pages, page_count, VM_MAP, prot);
 430         kfree(pages);
 431
 432         /*
 433          * Since vmap() uses page granularity, we must add the offset
 434          * into the page here, to get the byte granularity address
 435          * into the mapping to represent the actual "start" location.
 436          */
 437         return vaddr + offset_in_page(start);
 438 }
 439
 440 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
 441                 unsigned int memtype)
 442 {
 443         void *va;
 444
 445         if (!request_mem_region(start, size, "persistent_ram")) {
 446                 pr_err("request mem region (0x%llx@0x%llx) failed\n",
 447                         (unsigned long long)size, (unsigned long long)start);
 448                 return NULL;
 449         }
 450
 451         if (memtype)
 452                 va = ioremap(start, size);
 453         else
 454                 va = ioremap_wc(start, size);
 455
 456         /*
 457          * Since request_mem_region() and ioremap() are byte-granularity
 458          * there is no need handle anything special like we do when the
 459          * vmap() case in persistent_ram_vmap() above.
 460          */
 461         return va;
 462 }
 463
 464 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 465                 struct persistent_ram_zone *prz, int memtype)
 466 {
 467         prz->paddr = start;
 468         prz->size = size;
 469
 470         if (pfn_valid(start >> PAGE_SHIFT))
 471                 prz->vaddr = persistent_ram_vmap(start, size, memtype);
 472         else
 473                 prz->vaddr = persistent_ram_iomap(start, size, memtype);
 474
 475         if (!prz->vaddr) {
 476                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 477                         (unsigned long long)size, (unsigned long long)start);
 478                 return -ENOMEM;
 479         }
 480
 481         prz->buffer = prz->vaddr;
 482         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 483
 484         return 0;
 485 }
 486
 487 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 488                                     struct persistent_ram_ecc_info *ecc_info)
 489 {
 490         int ret;
 491
 492         ret = persistent_ram_init_ecc(prz, ecc_info);
 493         if (ret)
 494                 return ret;
 495
 496         sig ^= PERSISTENT_RAM_SIG;
 497
 498         if (prz->buffer->sig == sig) {
 499                 if (buffer_size(prz) == 0) {
 500                         pr_debug("found existing empty buffer\n");
 501                         return 0;
 502                 }
 503
 504                 if (buffer_size(prz) > prz->buffer_size ||
 505                     buffer_start(prz) > buffer_size(prz))
 506                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
 507                                 buffer_size(prz), buffer_start(prz));
 508                 else {
 509                         pr_debug("found existing buffer, size %zu, start %zu\n",
 510                                  buffer_size(prz), buffer_start(prz));
 511                         persistent_ram_save_old(prz);
 512                         return 0;
 513                 }
 514         } else {
 515                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 516                          prz->buffer->sig);
 517         }
 518
 519         /* Rewind missing or invalid memory area. */
 520         prz->buffer->sig = sig;
 521         persistent_ram_zap(prz);
 522
 523         return 0;
 524 }
 525
 526 void persistent_ram_free(struct persistent_ram_zone *prz)
 527 {
 528         if (!prz)
 529                 return;
 530
 531         if (prz->vaddr) {
 532                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 533                         /* We must vunmap() at page-granularity. */
 534                         vunmap(prz->vaddr - offset_in_page(prz->paddr));
 535                 } else {
 536                         iounmap(prz->vaddr);
 537                         release_mem_region(prz->paddr, prz->size);
 538                 }
 539                 prz->vaddr = NULL;
 540         }
 541         if (prz->rs_decoder) {
 542                 free_rs(prz->rs_decoder);
 543                 prz->rs_decoder = NULL;
 544         }
 545         kfree(prz->ecc_info.par);
 546         prz->ecc_info.par = NULL;
 547
 548         persistent_ram_free_old(prz);
 549         kfree(prz);
 550 }
 551
 552 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 553                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
 554                         unsigned int memtype, u32 flags)
 555 {
 556         struct persistent_ram_zone *prz;
 557         int ret = -ENOMEM;
 558
 559         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 560         if (!prz) {
 561                 pr_err("failed to allocate persistent ram zone\n");
 562                 goto err;
 563         }
 564
 565         /* Initialize general buffer state. */
 566         raw_spin_lock_init(&prz->buffer_lock);
 567         prz->flags = flags;
 568
 569         ret = persistent_ram_buffer_map(start, size, prz, memtype);
 570         if (ret)
 571                 goto err;
 572
 573         ret = persistent_ram_post_init(prz, sig, ecc_info);
 574         if (ret)
 575                 goto err;
 576
 577         return prz;
 578 err:
 579         persistent_ram_free(prz);
 580         return ERR_PTR(ret);
 581 }