kernel/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 static DEFINE_RAW_SPINLOCK(buffer_lock);
  51
  52 /* increase and wrap the start pointer, returning the old value */
  53 static size_t buffer_start_add(struct persistent_ram_zone *prz, size_t a)
  54 {
  55         int old;
  56         int new;
  57         unsigned long flags;
  58
  59         raw_spin_lock_irqsave(&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         raw_spin_unlock_irqrestore(&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;
  78
  79         raw_spin_lock_irqsave(&buffer_lock, flags);
  80
  81         old = atomic_read(&prz->buffer->size);
  82         if (old == prz->buffer_size)
  83                 goto exit;
  84
  85         new = old + a;
  86         if (new > prz->buffer_size)
  87                 new = prz->buffer_size;
  88         atomic_set(&prz->buffer->size, new);
  89
  90 exit:
  91         raw_spin_unlock_irqrestore(&buffer_lock, flags);
  92 }
  93
  94 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
  95         uint8_t *data, size_t len, uint8_t *ecc)
  96 {
  97         int i;
  98         uint16_t par[prz->ecc_info.ecc_size];
  99
 100         /* Initialize the parity buffer */
 101         memset(par, 0, sizeof(par));
 102         encode_rs8(prz->rs_decoder, data, len, par, 0);
 103         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 104                 ecc[i] = par[i];
 105 }
 106
 107 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 108         void *data, size_t len, uint8_t *ecc)
 109 {
 110         int i;
 111         uint16_t par[prz->ecc_info.ecc_size];
 112
 113         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 114                 par[i] = ecc[i];
 115         return decode_rs8(prz->rs_decoder, data, par, len,
 116                                 NULL, 0, NULL, 0, NULL);
 117 }
 118
 119 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 120         unsigned int start, unsigned int count)
 121 {
 122         struct persistent_ram_buffer *buffer = prz->buffer;
 123         uint8_t *buffer_end = buffer->data + prz->buffer_size;
 124         uint8_t *block;
 125         uint8_t *par;
 126         int ecc_block_size = prz->ecc_info.block_size;
 127         int ecc_size = prz->ecc_info.ecc_size;
 128         int size = ecc_block_size;
 129
 130         if (!ecc_size)
 131                 return;
 132
 133         block = buffer->data + (start & ~(ecc_block_size - 1));
 134         par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
 135
 136         do {
 137                 if (block + ecc_block_size > buffer_end)
 138                         size = buffer_end - block;
 139                 persistent_ram_encode_rs8(prz, block, size, par);
 140                 block += ecc_block_size;
 141                 par += ecc_size;
 142         } while (block < buffer->data + start + count);
 143 }
 144
 145 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
 146 {
 147         struct persistent_ram_buffer *buffer = prz->buffer;
 148
 149         if (!prz->ecc_info.ecc_size)
 150                 return;
 151
 152         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
 153                                   prz->par_header);
 154 }
 155
 156 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 157 {
 158         struct persistent_ram_buffer *buffer = prz->buffer;
 159         uint8_t *block;
 160         uint8_t *par;
 161
 162         if (!prz->ecc_info.ecc_size)
 163                 return;
 164
 165         block = buffer->data;
 166         par = prz->par_buffer;
 167         while (block < buffer->data + buffer_size(prz)) {
 168                 int numerr;
 169                 int size = prz->ecc_info.block_size;
 170                 if (block + size > buffer->data + prz->buffer_size)
 171                         size = buffer->data + prz->buffer_size - block;
 172                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
 173                 if (numerr > 0) {
 174                         pr_devel("error in block %p, %d\n", block, numerr);
 175                         prz->corrected_bytes += numerr;
 176                 } else if (numerr < 0) {
 177                         pr_devel("uncorrectable error in block %p\n", block);
 178                         prz->bad_blocks++;
 179                 }
 180                 block += prz->ecc_info.block_size;
 181                 par += prz->ecc_info.ecc_size;
 182         }
 183 }
 184
 185 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 186                                    struct persistent_ram_ecc_info *ecc_info)
 187 {
 188         int numerr;
 189         struct persistent_ram_buffer *buffer = prz->buffer;
 190         int ecc_blocks;
 191         size_t ecc_total;
 192
 193         if (!ecc_info || !ecc_info->ecc_size)
 194                 return 0;
 195
 196         prz->ecc_info.block_size = ecc_info->block_size ?: 128;
 197         prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
 198         prz->ecc_info.symsize = ecc_info->symsize ?: 8;
 199         prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
 200
 201         ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
 202                                   prz->ecc_info.block_size +
 203                                   prz->ecc_info.ecc_size);
 204         ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
 205         if (ecc_total >= prz->buffer_size) {
 206                 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
 207                        __func__, prz->ecc_info.ecc_size,
 208                        ecc_total, prz->buffer_size);
 209                 return -EINVAL;
 210         }
 211
 212         prz->buffer_size -= ecc_total;
 213         prz->par_buffer = buffer->data + prz->buffer_size;
 214         prz->par_header = prz->par_buffer +
 215                           ecc_blocks * prz->ecc_info.ecc_size;
 216
 217         /*
 218          * first consecutive root is 0
 219          * primitive element to generate roots = 1
 220          */
 221         prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
 222                                   0, 1, prz->ecc_info.ecc_size);
 223         if (prz->rs_decoder == NULL) {
 224                 pr_info("init_rs failed\n");
 225                 return -EINVAL;
 226         }
 227
 228         prz->corrected_bytes = 0;
 229         prz->bad_blocks = 0;
 230
 231         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 232                                            prz->par_header);
 233         if (numerr > 0) {
 234                 pr_info("error in header, %d\n", numerr);
 235                 prz->corrected_bytes += numerr;
 236         } else if (numerr < 0) {
 237                 pr_info("uncorrectable error in header\n");
 238                 prz->bad_blocks++;
 239         }
 240
 241         return 0;
 242 }
 243
 244 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 245         char *str, size_t len)
 246 {
 247         ssize_t ret;
 248
 249         if (!prz->ecc_info.ecc_size)
 250                 return 0;
 251
 252         if (prz->corrected_bytes || prz->bad_blocks)
 253                 ret = snprintf(str, len, ""
 254                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 255                         prz->corrected_bytes, prz->bad_blocks);
 256         else
 257                 ret = snprintf(str, len, "\nNo errors detected\n");
 258
 259         return ret;
 260 }
 261
 262 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 263         const void *s, unsigned int start, unsigned int count)
 264 {
 265         struct persistent_ram_buffer *buffer = prz->buffer;
 266         memcpy_toio(buffer->data + start, s, count);
 267         persistent_ram_update_ecc(prz, start, count);
 268 }
 269
 270 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 271 {
 272         struct persistent_ram_buffer *buffer = prz->buffer;
 273         size_t size = buffer_size(prz);
 274         size_t start = buffer_start(prz);
 275
 276         if (!size)
 277                 return;
 278
 279         if (!prz->old_log) {
 280                 persistent_ram_ecc_old(prz);
 281                 prz->old_log = kmalloc(size, GFP_KERNEL);
 282         }
 283         if (!prz->old_log) {
 284                 pr_err("failed to allocate buffer\n");
 285                 return;
 286         }
 287
 288         prz->old_log_size = size;
 289         memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
 290         memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
 291 }
 292
 293 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 294         const void *s, unsigned int count)
 295 {
 296         int rem;
 297         int c = count;
 298         size_t start;
 299
 300         if (unlikely(c > prz->buffer_size)) {
 301                 s += c - prz->buffer_size;
 302                 c = prz->buffer_size;
 303         }
 304
 305         buffer_size_add(prz, c);
 306
 307         start = buffer_start_add(prz, c);
 308
 309         rem = prz->buffer_size - start;
 310         if (unlikely(rem < c)) {
 311                 persistent_ram_update(prz, s, start, rem);
 312                 s += rem;
 313                 c -= rem;
 314                 start = 0;
 315         }
 316         persistent_ram_update(prz, s, start, c);
 317
 318         persistent_ram_update_header_ecc(prz);
 319
 320         return count;
 321 }
 322
 323 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 324 {
 325         return prz->old_log_size;
 326 }
 327
 328 void *persistent_ram_old(struct persistent_ram_zone *prz)
 329 {
 330         return prz->old_log;
 331 }
 332
 333 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 334 {
 335         kfree(prz->old_log);
 336         prz->old_log = NULL;
 337         prz->old_log_size = 0;
 338 }
 339
 340 void persistent_ram_zap(struct persistent_ram_zone *prz)
 341 {
 342         atomic_set(&prz->buffer->start, 0);
 343         atomic_set(&prz->buffer->size, 0);
 344         persistent_ram_update_header_ecc(prz);
 345 }
 346
 347 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 348                 unsigned int memtype)
 349 {
 350         struct page **pages;
 351         phys_addr_t page_start;
 352         unsigned int page_count;
 353         pgprot_t prot;
 354         unsigned int i;
 355         void *vaddr;
 356
 357         page_start = start - offset_in_page(start);
 358         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 359
 360         if (memtype)
 361                 prot = pgprot_noncached(PAGE_KERNEL);
 362         else
 363                 prot = pgprot_writecombine(PAGE_KERNEL);
 364
 365         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
 366         if (!pages) {
 367                 pr_err("%s: Failed to allocate array for %u pages\n",
 368                        __func__, page_count);
 369                 return NULL;
 370         }
 371
 372         for (i = 0; i < page_count; i++) {
 373                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 374                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 375         }
 376         vaddr = vmap(pages, page_count, VM_MAP, prot);
 377         kfree(pages);
 378
 379         return vaddr;
 380 }
 381
 382 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
 383                 unsigned int memtype)
 384 {
 385         void *va;
 386
 387         if (!request_mem_region(start, size, "persistent_ram")) {
 388                 pr_err("request mem region (0x%llx@0x%llx) failed\n",
 389                         (unsigned long long)size, (unsigned long long)start);
 390                 return NULL;
 391         }
 392
 393         if (memtype)
 394                 va = ioremap(start, size);
 395         else
 396                 va = ioremap_wc(start, size);
 397
 398         return va;
 399 }
 400
 401 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 402                 struct persistent_ram_zone *prz, int memtype)
 403 {
 404         prz->paddr = start;
 405         prz->size = size;
 406
 407         if (pfn_valid(start >> PAGE_SHIFT))
 408                 prz->vaddr = persistent_ram_vmap(start, size, memtype);
 409         else
 410                 prz->vaddr = persistent_ram_iomap(start, size, memtype);
 411
 412         if (!prz->vaddr) {
 413                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 414                         (unsigned long long)size, (unsigned long long)start);
 415                 return -ENOMEM;
 416         }
 417
 418         prz->buffer = prz->vaddr + offset_in_page(start);
 419         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 420
 421         return 0;
 422 }
 423
 424 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 425                                     struct persistent_ram_ecc_info *ecc_info)
 426 {
 427         int ret;
 428
 429         ret = persistent_ram_init_ecc(prz, ecc_info);
 430         if (ret)
 431                 return ret;
 432
 433         sig ^= PERSISTENT_RAM_SIG;
 434
 435         if (prz->buffer->sig == sig) {
 436                 if (buffer_size(prz) > prz->buffer_size ||
 437                     buffer_start(prz) > buffer_size(prz))
 438                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
 439                                 buffer_size(prz), buffer_start(prz));
 440                 else {
 441                         pr_debug("found existing buffer, size %zu, start %zu\n",
 442                                  buffer_size(prz), buffer_start(prz));
 443                         persistent_ram_save_old(prz);
 444                         return 0;
 445                 }
 446         } else {
 447                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 448                          prz->buffer->sig);
 449         }
 450
 451         prz->buffer->sig = sig;
 452         persistent_ram_zap(prz);
 453
 454         return 0;
 455 }
 456
 457 void persistent_ram_free(struct persistent_ram_zone *prz)
 458 {
 459         if (!prz)
 460                 return;
 461
 462         if (prz->vaddr) {
 463                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 464                         vunmap(prz->vaddr);
 465                 } else {
 466                         iounmap(prz->vaddr);
 467                         release_mem_region(prz->paddr, prz->size);
 468                 }
 469                 prz->vaddr = NULL;
 470         }
 471         persistent_ram_free_old(prz);
 472         kfree(prz);
 473 }
 474
 475 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 476                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
 477                         unsigned int memtype)
 478 {
 479         struct persistent_ram_zone *prz;
 480         int ret = -ENOMEM;
 481
 482         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 483         if (!prz) {
 484                 pr_err("failed to allocate persistent ram zone\n");
 485                 goto err;
 486         }
 487
 488         ret = persistent_ram_buffer_map(start, size, prz, memtype);
 489         if (ret)
 490                 goto err;
 491
 492         ret = persistent_ram_post_init(prz, sig, ecc_info);
 493         if (ret)
 494                 goto err;
 495
 496         return prz;
 497 err:
 498         persistent_ram_free(prz);
 499         return ERR_PTR(ret);
 500 }