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 static DEFINE_RAW_SPINLOCK(buffer_lock);
  52
  53 /* increase and wrap the start pointer, returning the old value */
  54 static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
  55 {
  56         int old;
  57         int new;
  58         unsigned long flags;
  59
  60         raw_spin_lock_irqsave(&buffer_lock, flags);
  61
  62         old = atomic_read(&prz->buffer->start);
  63         new = old + a;
  64         while (unlikely(new >= prz->buffer_size))
  65                 new -= prz->buffer_size;
  66         atomic_set(&prz->buffer->start, new);
  67
  68         raw_spin_unlock_irqrestore(&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;
  79
  80         raw_spin_lock_irqsave(&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         raw_spin_unlock_irqrestore(&buffer_lock, flags);
  93 }
  94
  95 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
  96         uint8_t *data, size_t len, uint8_t *ecc)
  97 {
  98         int i;
  99         uint16_t par[prz->ecc_info.ecc_size];
 100
 101         /* Initialize the parity buffer */
 102         memset(par, 0, sizeof(par));
 103         encode_rs8(prz->rs_decoder, data, len, par, 0);
 104         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 105                 ecc[i] = par[i];
 106 }
 107
 108 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 109         void *data, size_t len, uint8_t *ecc)
 110 {
 111         int i;
 112         uint16_t par[prz->ecc_info.ecc_size];
 113
 114         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 115                 par[i] = ecc[i];
 116         return decode_rs8(prz->rs_decoder, data, par, len,
 117                                 NULL, 0, NULL, 0, NULL);
 118 }
 119
 120 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 121         unsigned int start, unsigned int count)
 122 {
 123         struct persistent_ram_buffer *buffer = prz->buffer;
 124         uint8_t *buffer_end = buffer->data + prz->buffer_size;
 125         uint8_t *block;
 126         uint8_t *par;
 127         int ecc_block_size = prz->ecc_info.block_size;
 128         int ecc_size = prz->ecc_info.ecc_size;
 129         int size = ecc_block_size;
 130
 131         if (!ecc_size)
 132                 return;
 133
 134         block = buffer->data + (start & ~(ecc_block_size - 1));
 135         par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
 136
 137         do {
 138                 if (block + ecc_block_size > buffer_end)
 139                         size = buffer_end - block;
 140                 persistent_ram_encode_rs8(prz, block, size, par);
 141                 block += ecc_block_size;
 142                 par += ecc_size;
 143         } while (block < buffer->data + start + count);
 144 }
 145
 146 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
 147 {
 148         struct persistent_ram_buffer *buffer = prz->buffer;
 149
 150         if (!prz->ecc_info.ecc_size)
 151                 return;
 152
 153         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
 154                                   prz->par_header);
 155 }
 156
 157 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 158 {
 159         struct persistent_ram_buffer *buffer = prz->buffer;
 160         uint8_t *block;
 161         uint8_t *par;
 162
 163         if (!prz->ecc_info.ecc_size)
 164                 return;
 165
 166         block = buffer->data;
 167         par = prz->par_buffer;
 168         while (block < buffer->data + buffer_size(prz)) {
 169                 int numerr;
 170                 int size = prz->ecc_info.block_size;
 171                 if (block + size > buffer->data + prz->buffer_size)
 172                         size = buffer->data + prz->buffer_size - block;
 173                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
 174                 if (numerr > 0) {
 175                         pr_devel("error in block %p, %d\n", block, numerr);
 176                         prz->corrected_bytes += numerr;
 177                 } else if (numerr < 0) {
 178                         pr_devel("uncorrectable error in block %p\n", block);
 179                         prz->bad_blocks++;
 180                 }
 181                 block += prz->ecc_info.block_size;
 182                 par += prz->ecc_info.ecc_size;
 183         }
 184 }
 185
 186 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 187                                    struct persistent_ram_ecc_info *ecc_info)
 188 {
 189         int numerr;
 190         struct persistent_ram_buffer *buffer = prz->buffer;
 191         int ecc_blocks;
 192         size_t ecc_total;
 193
 194         if (!ecc_info || !ecc_info->ecc_size)
 195                 return 0;
 196
 197         prz->ecc_info.block_size = ecc_info->block_size ?: 128;
 198         prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
 199         prz->ecc_info.symsize = ecc_info->symsize ?: 8;
 200         prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
 201
 202         ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
 203                                   prz->ecc_info.block_size +
 204                                   prz->ecc_info.ecc_size);
 205         ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
 206         if (ecc_total >= prz->buffer_size) {
 207                 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
 208                        __func__, prz->ecc_info.ecc_size,
 209                        ecc_total, prz->buffer_size);
 210                 return -EINVAL;
 211         }
 212
 213         prz->buffer_size -= ecc_total;
 214         prz->par_buffer = buffer->data + prz->buffer_size;
 215         prz->par_header = prz->par_buffer +
 216                           ecc_blocks * prz->ecc_info.ecc_size;
 217
 218         /*
 219          * first consecutive root is 0
 220          * primitive element to generate roots = 1
 221          */
 222         prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
 223                                   0, 1, prz->ecc_info.ecc_size);
 224         if (prz->rs_decoder == NULL) {
 225                 pr_info("init_rs failed\n");
 226                 return -EINVAL;
 227         }
 228
 229         prz->corrected_bytes = 0;
 230         prz->bad_blocks = 0;
 231
 232         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 233                                            prz->par_header);
 234         if (numerr > 0) {
 235                 pr_info("error in header, %d\n", numerr);
 236                 prz->corrected_bytes += numerr;
 237         } else if (numerr < 0) {
 238                 pr_info("uncorrectable error in header\n");
 239                 prz->bad_blocks++;
 240         }
 241
 242         return 0;
 243 }
 244
 245 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 246         char *str, size_t len)
 247 {
 248         ssize_t ret;
 249
 250         if (!prz->ecc_info.ecc_size)
 251                 return 0;
 252
 253         if (prz->corrected_bytes || prz->bad_blocks)
 254                 ret = snprintf(str, len, ""
 255                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 256                         prz->corrected_bytes, prz->bad_blocks);
 257         else
 258                 ret = snprintf(str, len, "\nNo errors detected\n");
 259
 260         return ret;
 261 }
 262
 263 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 264         const void *s, unsigned int start, unsigned int count)
 265 {
 266         struct persistent_ram_buffer *buffer = prz->buffer;
 267         memcpy_toio(buffer->data + start, s, count);
 268         persistent_ram_update_ecc(prz, start, count);
 269 }
 270
 271 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
 272         const void __user *s, unsigned int start, unsigned int count)
 273 {
 274         struct persistent_ram_buffer *buffer = prz->buffer;
 275         int ret = unlikely(__copy_from_user(buffer->data + start, s, count)) ?
 276                 -EFAULT : 0;
 277         persistent_ram_update_ecc(prz, start, count);
 278         return ret;
 279 }
 280
 281 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 282 {
 283         struct persistent_ram_buffer *buffer = prz->buffer;
 284         size_t size = buffer_size(prz);
 285         size_t start = buffer_start(prz);
 286
 287         if (!size)
 288                 return;
 289
 290         if (!prz->old_log) {
 291                 persistent_ram_ecc_old(prz);
 292                 prz->old_log = kmalloc(size, GFP_KERNEL);
 293         }
 294         if (!prz->old_log) {
 295                 pr_err("failed to allocate buffer\n");
 296                 return;
 297         }
 298
 299         prz->old_log_size = size;
 300         memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
 301         memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
 302 }
 303
 304 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 305         const void *s, unsigned int count)
 306 {
 307         int rem;
 308         int c = count;
 309         size_t start;
 310
 311         if (unlikely(c > prz->buffer_size)) {
 312                 s += c - prz->buffer_size;
 313                 c = prz->buffer_size;
 314         }
 315
 316         buffer_size_add(prz, c);
 317
 318         start = buffer_start_add(prz, c);
 319
 320         rem = prz->buffer_size - start;
 321         if (unlikely(rem < c)) {
 322                 persistent_ram_update(prz, s, start, rem);
 323                 s += rem;
 324                 c -= rem;
 325                 start = 0;
 326         }
 327         persistent_ram_update(prz, s, start, c);
 328
 329         persistent_ram_update_header_ecc(prz);
 330
 331         return count;
 332 }
 333
 334 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
 335         const void __user *s, unsigned int count)
 336 {
 337         int rem, ret = 0, c = count;
 338         size_t start;
 339
 340         if (unlikely(!access_ok(VERIFY_READ, s, count)))
 341                 return -EFAULT;
 342         if (unlikely(c > prz->buffer_size)) {
 343                 s += c - prz->buffer_size;
 344                 c = prz->buffer_size;
 345         }
 346
 347         buffer_size_add(prz, c);
 348
 349         start = buffer_start_add(prz, c);
 350
 351         rem = prz->buffer_size - start;
 352         if (unlikely(rem < c)) {
 353                 ret = persistent_ram_update_user(prz, s, start, rem);
 354                 s += rem;
 355                 c -= rem;
 356                 start = 0;
 357         }
 358         if (likely(!ret))
 359                 ret = persistent_ram_update_user(prz, s, start, c);
 360
 361         persistent_ram_update_header_ecc(prz);
 362
 363         return unlikely(ret) ? ret : count;
 364 }
 365
 366 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 367 {
 368         return prz->old_log_size;
 369 }
 370
 371 void *persistent_ram_old(struct persistent_ram_zone *prz)
 372 {
 373         return prz->old_log;
 374 }
 375
 376 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 377 {
 378         kfree(prz->old_log);
 379         prz->old_log = NULL;
 380         prz->old_log_size = 0;
 381 }
 382
 383 void persistent_ram_zap(struct persistent_ram_zone *prz)
 384 {
 385         atomic_set(&prz->buffer->start, 0);
 386         atomic_set(&prz->buffer->size, 0);
 387         persistent_ram_update_header_ecc(prz);
 388 }
 389
 390 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 391                 unsigned int memtype)
 392 {
 393         struct page **pages;
 394         phys_addr_t page_start;
 395         unsigned int page_count;
 396         pgprot_t prot;
 397         unsigned int i;
 398         void *vaddr;
 399
 400         page_start = start - offset_in_page(start);
 401         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 402
 403         if (memtype)
 404                 prot = pgprot_noncached(PAGE_KERNEL);
 405         else
 406                 prot = pgprot_writecombine(PAGE_KERNEL);
 407
 408         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
 409         if (!pages) {
 410                 pr_err("%s: Failed to allocate array for %u pages\n",
 411                        __func__, page_count);
 412                 return NULL;
 413         }
 414
 415         for (i = 0; i < page_count; i++) {
 416                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 417                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 418         }
 419         vaddr = vmap(pages, page_count, VM_MAP, prot);
 420         kfree(pages);
 421
 422         return vaddr;
 423 }
 424
 425 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
 426                 unsigned int memtype)
 427 {
 428         void *va;
 429
 430         if (!request_mem_region(start, size, "persistent_ram")) {
 431                 pr_err("request mem region (0x%llx@0x%llx) failed\n",
 432                         (unsigned long long)size, (unsigned long long)start);
 433                 return NULL;
 434         }
 435
 436         if (memtype)
 437                 va = ioremap(start, size);
 438         else
 439                 va = ioremap_wc(start, size);
 440
 441         return va;
 442 }
 443
 444 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 445                 struct persistent_ram_zone *prz, int memtype)
 446 {
 447         prz->paddr = start;
 448         prz->size = size;
 449
 450         if (pfn_valid(start >> PAGE_SHIFT))
 451                 prz->vaddr = persistent_ram_vmap(start, size, memtype);
 452         else
 453                 prz->vaddr = persistent_ram_iomap(start, size, memtype);
 454
 455         if (!prz->vaddr) {
 456                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 457                         (unsigned long long)size, (unsigned long long)start);
 458                 return -ENOMEM;
 459         }
 460
 461         prz->buffer = prz->vaddr + offset_in_page(start);
 462         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 463
 464         return 0;
 465 }
 466
 467 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 468                                     struct persistent_ram_ecc_info *ecc_info)
 469 {
 470         int ret;
 471
 472         ret = persistent_ram_init_ecc(prz, ecc_info);
 473         if (ret)
 474                 return ret;
 475
 476         sig ^= PERSISTENT_RAM_SIG;
 477
 478         if (prz->buffer->sig == sig) {
 479                 if (buffer_size(prz) > prz->buffer_size ||
 480                     buffer_start(prz) > buffer_size(prz))
 481                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
 482                                 buffer_size(prz), buffer_start(prz));
 483                 else {
 484                         pr_debug("found existing buffer, size %zu, start %zu\n",
 485                                  buffer_size(prz), buffer_start(prz));
 486                         persistent_ram_save_old(prz);
 487                         return 0;
 488                 }
 489         } else {
 490                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 491                          prz->buffer->sig);
 492         }
 493
 494         prz->buffer->sig = sig;
 495         persistent_ram_zap(prz);
 496
 497         return 0;
 498 }
 499
 500 void persistent_ram_free(struct persistent_ram_zone *prz)
 501 {
 502         if (!prz)
 503                 return;
 504
 505         if (prz->vaddr) {
 506                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 507                         vunmap(prz->vaddr);
 508                 } else {
 509                         iounmap(prz->vaddr);
 510                         release_mem_region(prz->paddr, prz->size);
 511                 }
 512                 prz->vaddr = NULL;
 513         }
 514         persistent_ram_free_old(prz);
 515         kfree(prz);
 516 }
 517
 518 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 519                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
 520                         unsigned int memtype)
 521 {
 522         struct persistent_ram_zone *prz;
 523         int ret = -ENOMEM;
 524
 525         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 526         if (!prz) {
 527                 pr_err("failed to allocate persistent ram zone\n");
 528                 goto err;
 529         }
 530
 531         ret = persistent_ram_buffer_map(start, size, prz, memtype);
 532         if (ret)
 533                 goto err;
 534
 535         ret = persistent_ram_post_init(prz, sig, ecc_info);
 536         if (ret)
 537                 goto err;
 538
 539         return prz;
 540 err:
 541         persistent_ram_free(prz);
 542         return ERR_PTR(ret);
 543 }