root/fs/pstore/ram_core.c

DEFINITIONS

1. buffer_size
2. buffer_start
3. buffer_start_add
4. buffer_size_add
5. persistent_ram_encode_rs8
6. persistent_ram_decode_rs8
7. persistent_ram_update_ecc
8. persistent_ram_update_header_ecc
9. persistent_ram_ecc_old
10. persistent_ram_init_ecc
11. persistent_ram_ecc_string
12. persistent_ram_update
13. persistent_ram_update_user
14. persistent_ram_save_old
15. persistent_ram_write
16. persistent_ram_write_user
17. persistent_ram_old_size
18. persistent_ram_old
19. persistent_ram_free_old
20. persistent_ram_zap
21. persistent_ram_vmap
22. persistent_ram_iomap
23. persistent_ram_buffer_map
24. persistent_ram_post_init
25. persistent_ram_free
26. persistent_ram_new

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Google, Inc.
   4  */
   5 
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7 
   8 #include <linux/device.h>
   9 #include <linux/err.h>
  10 #include <linux/errno.h>
  11 #include <linux/init.h>
  12 #include <linux/io.h>
  13 #include <linux/kernel.h>
  14 #include <linux/list.h>
  15 #include <linux/memblock.h>
  16 #include <linux/pstore_ram.h>
  17 #include <linux/rslib.h>
  18 #include <linux/slab.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/vmalloc.h>
  21 #include <asm/page.h>
  22 
  23 /**
  24  * struct persistent_ram_buffer - persistent circular RAM buffer
  25  *
  26  * @sig:
  27  *      signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
  28  * @start:
  29  *      offset into @data where the beginning of the stored bytes begin
  30  * @size:
  31  *      number of valid bytes stored in @data
  32  */
  33 struct persistent_ram_buffer {
  34         uint32_t    sig;
  35         atomic_t    start;
  36         atomic_t    size;
  37         uint8_t     data[0];
  38 };
  39 
  40 #define PERSISTENT_RAM_SIG (0x43474244) /* DBGC */
  41 
  42 static inline size_t buffer_size(struct persistent_ram_zone *prz)
  43 {
  44         return atomic_read(&prz->buffer->size);
  45 }
  46 
  47 static inline size_t buffer_start(struct persistent_ram_zone *prz)
  48 {
  49         return atomic_read(&prz->buffer->start);
  50 }
  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 = 0;
  58 
  59         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  60                 raw_spin_lock_irqsave(&prz->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         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  69                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
  70 
  71         return old;
  72 }
  73 
  74 /* increase the size counter until it hits the max size */
  75 static void buffer_size_add(struct persistent_ram_zone *prz, size_t a)
  76 {
  77         size_t old;
  78         size_t new;
  79         unsigned long flags = 0;
  80 
  81         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  82                 raw_spin_lock_irqsave(&prz->buffer_lock, flags);
  83 
  84         old = atomic_read(&prz->buffer->size);
  85         if (old == prz->buffer_size)
  86                 goto exit;
  87 
  88         new = old + a;
  89         if (new > prz->buffer_size)
  90                 new = prz->buffer_size;
  91         atomic_set(&prz->buffer->size, new);
  92 
  93 exit:
  94         if (!(prz->flags & PRZ_FLAG_NO_LOCK))
  95                 raw_spin_unlock_irqrestore(&prz->buffer_lock, flags);
  96 }
  97 
  98 static void notrace persistent_ram_encode_rs8(struct persistent_ram_zone *prz,
  99         uint8_t *data, size_t len, uint8_t *ecc)
 100 {
 101         int i;
 102 
 103         /* Initialize the parity buffer */
 104         memset(prz->ecc_info.par, 0,
 105                prz->ecc_info.ecc_size * sizeof(prz->ecc_info.par[0]));
 106         encode_rs8(prz->rs_decoder, data, len, prz->ecc_info.par, 0);
 107         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 108                 ecc[i] = prz->ecc_info.par[i];
 109 }
 110 
 111 static int persistent_ram_decode_rs8(struct persistent_ram_zone *prz,
 112         void *data, size_t len, uint8_t *ecc)
 113 {
 114         int i;
 115 
 116         for (i = 0; i < prz->ecc_info.ecc_size; i++)
 117                 prz->ecc_info.par[i] = ecc[i];
 118         return decode_rs8(prz->rs_decoder, data, prz->ecc_info.par, len,
 119                                 NULL, 0, NULL, 0, NULL);
 120 }
 121 
 122 static void notrace persistent_ram_update_ecc(struct persistent_ram_zone *prz,
 123         unsigned int start, unsigned int count)
 124 {
 125         struct persistent_ram_buffer *buffer = prz->buffer;
 126         uint8_t *buffer_end = buffer->data + prz->buffer_size;
 127         uint8_t *block;
 128         uint8_t *par;
 129         int ecc_block_size = prz->ecc_info.block_size;
 130         int ecc_size = prz->ecc_info.ecc_size;
 131         int size = ecc_block_size;
 132 
 133         if (!ecc_size)
 134                 return;
 135 
 136         block = buffer->data + (start & ~(ecc_block_size - 1));
 137         par = prz->par_buffer + (start / ecc_block_size) * ecc_size;
 138 
 139         do {
 140                 if (block + ecc_block_size > buffer_end)
 141                         size = buffer_end - block;
 142                 persistent_ram_encode_rs8(prz, block, size, par);
 143                 block += ecc_block_size;
 144                 par += ecc_size;
 145         } while (block < buffer->data + start + count);
 146 }
 147 
 148 static void persistent_ram_update_header_ecc(struct persistent_ram_zone *prz)
 149 {
 150         struct persistent_ram_buffer *buffer = prz->buffer;
 151 
 152         if (!prz->ecc_info.ecc_size)
 153                 return;
 154 
 155         persistent_ram_encode_rs8(prz, (uint8_t *)buffer, sizeof(*buffer),
 156                                   prz->par_header);
 157 }
 158 
 159 static void persistent_ram_ecc_old(struct persistent_ram_zone *prz)
 160 {
 161         struct persistent_ram_buffer *buffer = prz->buffer;
 162         uint8_t *block;
 163         uint8_t *par;
 164 
 165         if (!prz->ecc_info.ecc_size)
 166                 return;
 167 
 168         block = buffer->data;
 169         par = prz->par_buffer;
 170         while (block < buffer->data + buffer_size(prz)) {
 171                 int numerr;
 172                 int size = prz->ecc_info.block_size;
 173                 if (block + size > buffer->data + prz->buffer_size)
 174                         size = buffer->data + prz->buffer_size - block;
 175                 numerr = persistent_ram_decode_rs8(prz, block, size, par);
 176                 if (numerr > 0) {
 177                         pr_devel("error in block %p, %d\n", block, numerr);
 178                         prz->corrected_bytes += numerr;
 179                 } else if (numerr < 0) {
 180                         pr_devel("uncorrectable error in block %p\n", block);
 181                         prz->bad_blocks++;
 182                 }
 183                 block += prz->ecc_info.block_size;
 184                 par += prz->ecc_info.ecc_size;
 185         }
 186 }
 187 
 188 static int persistent_ram_init_ecc(struct persistent_ram_zone *prz,
 189                                    struct persistent_ram_ecc_info *ecc_info)
 190 {
 191         int numerr;
 192         struct persistent_ram_buffer *buffer = prz->buffer;
 193         int ecc_blocks;
 194         size_t ecc_total;
 195 
 196         if (!ecc_info || !ecc_info->ecc_size)
 197                 return 0;
 198 
 199         prz->ecc_info.block_size = ecc_info->block_size ?: 128;
 200         prz->ecc_info.ecc_size = ecc_info->ecc_size ?: 16;
 201         prz->ecc_info.symsize = ecc_info->symsize ?: 8;
 202         prz->ecc_info.poly = ecc_info->poly ?: 0x11d;
 203 
 204         ecc_blocks = DIV_ROUND_UP(prz->buffer_size - prz->ecc_info.ecc_size,
 205                                   prz->ecc_info.block_size +
 206                                   prz->ecc_info.ecc_size);
 207         ecc_total = (ecc_blocks + 1) * prz->ecc_info.ecc_size;
 208         if (ecc_total >= prz->buffer_size) {
 209                 pr_err("%s: invalid ecc_size %u (total %zu, buffer size %zu)\n",
 210                        __func__, prz->ecc_info.ecc_size,
 211                        ecc_total, prz->buffer_size);
 212                 return -EINVAL;
 213         }
 214 
 215         prz->buffer_size -= ecc_total;
 216         prz->par_buffer = buffer->data + prz->buffer_size;
 217         prz->par_header = prz->par_buffer +
 218                           ecc_blocks * prz->ecc_info.ecc_size;
 219 
 220         /*
 221          * first consecutive root is 0
 222          * primitive element to generate roots = 1
 223          */
 224         prz->rs_decoder = init_rs(prz->ecc_info.symsize, prz->ecc_info.poly,
 225                                   0, 1, prz->ecc_info.ecc_size);
 226         if (prz->rs_decoder == NULL) {
 227                 pr_info("init_rs failed\n");
 228                 return -EINVAL;
 229         }
 230 
 231         /* allocate workspace instead of using stack VLA */
 232         prz->ecc_info.par = kmalloc_array(prz->ecc_info.ecc_size,
 233                                           sizeof(*prz->ecc_info.par),
 234                                           GFP_KERNEL);
 235         if (!prz->ecc_info.par) {
 236                 pr_err("cannot allocate ECC parity workspace\n");
 237                 return -ENOMEM;
 238         }
 239 
 240         prz->corrected_bytes = 0;
 241         prz->bad_blocks = 0;
 242 
 243         numerr = persistent_ram_decode_rs8(prz, buffer, sizeof(*buffer),
 244                                            prz->par_header);
 245         if (numerr > 0) {
 246                 pr_info("error in header, %d\n", numerr);
 247                 prz->corrected_bytes += numerr;
 248         } else if (numerr < 0) {
 249                 pr_info("uncorrectable error in header\n");
 250                 prz->bad_blocks++;
 251         }
 252 
 253         return 0;
 254 }
 255 
 256 ssize_t persistent_ram_ecc_string(struct persistent_ram_zone *prz,
 257         char *str, size_t len)
 258 {
 259         ssize_t ret;
 260 
 261         if (!prz->ecc_info.ecc_size)
 262                 return 0;
 263 
 264         if (prz->corrected_bytes || prz->bad_blocks)
 265                 ret = snprintf(str, len, ""
 266                         "\n%d Corrected bytes, %d unrecoverable blocks\n",
 267                         prz->corrected_bytes, prz->bad_blocks);
 268         else
 269                 ret = snprintf(str, len, "\nNo errors detected\n");
 270 
 271         return ret;
 272 }
 273 
 274 static void notrace persistent_ram_update(struct persistent_ram_zone *prz,
 275         const void *s, unsigned int start, unsigned int count)
 276 {
 277         struct persistent_ram_buffer *buffer = prz->buffer;
 278         memcpy_toio(buffer->data + start, s, count);
 279         persistent_ram_update_ecc(prz, start, count);
 280 }
 281 
 282 static int notrace persistent_ram_update_user(struct persistent_ram_zone *prz,
 283         const void __user *s, unsigned int start, unsigned int count)
 284 {
 285         struct persistent_ram_buffer *buffer = prz->buffer;
 286         int ret = unlikely(__copy_from_user(buffer->data + start, s, count)) ?
 287                 -EFAULT : 0;
 288         persistent_ram_update_ecc(prz, start, count);
 289         return ret;
 290 }
 291 
 292 void persistent_ram_save_old(struct persistent_ram_zone *prz)
 293 {
 294         struct persistent_ram_buffer *buffer = prz->buffer;
 295         size_t size = buffer_size(prz);
 296         size_t start = buffer_start(prz);
 297 
 298         if (!size)
 299                 return;
 300 
 301         if (!prz->old_log) {
 302                 persistent_ram_ecc_old(prz);
 303                 prz->old_log = kmalloc(size, GFP_KERNEL);
 304         }
 305         if (!prz->old_log) {
 306                 pr_err("failed to allocate buffer\n");
 307                 return;
 308         }
 309 
 310         prz->old_log_size = size;
 311         memcpy_fromio(prz->old_log, &buffer->data[start], size - start);
 312         memcpy_fromio(prz->old_log + size - start, &buffer->data[0], start);
 313 }
 314 
 315 int notrace persistent_ram_write(struct persistent_ram_zone *prz,
 316         const void *s, unsigned int count)
 317 {
 318         int rem;
 319         int c = count;
 320         size_t start;
 321 
 322         if (unlikely(c > prz->buffer_size)) {
 323                 s += c - prz->buffer_size;
 324                 c = prz->buffer_size;
 325         }
 326 
 327         buffer_size_add(prz, c);
 328 
 329         start = buffer_start_add(prz, c);
 330 
 331         rem = prz->buffer_size - start;
 332         if (unlikely(rem < c)) {
 333                 persistent_ram_update(prz, s, start, rem);
 334                 s += rem;
 335                 c -= rem;
 336                 start = 0;
 337         }
 338         persistent_ram_update(prz, s, start, c);
 339 
 340         persistent_ram_update_header_ecc(prz);
 341 
 342         return count;
 343 }
 344 
 345 int notrace persistent_ram_write_user(struct persistent_ram_zone *prz,
 346         const void __user *s, unsigned int count)
 347 {
 348         int rem, ret = 0, c = count;
 349         size_t start;
 350 
 351         if (unlikely(!access_ok(s, count)))
 352                 return -EFAULT;
 353         if (unlikely(c > prz->buffer_size)) {
 354                 s += c - prz->buffer_size;
 355                 c = prz->buffer_size;
 356         }
 357 
 358         buffer_size_add(prz, c);
 359 
 360         start = buffer_start_add(prz, c);
 361 
 362         rem = prz->buffer_size - start;
 363         if (unlikely(rem < c)) {
 364                 ret = persistent_ram_update_user(prz, s, start, rem);
 365                 s += rem;
 366                 c -= rem;
 367                 start = 0;
 368         }
 369         if (likely(!ret))
 370                 ret = persistent_ram_update_user(prz, s, start, c);
 371 
 372         persistent_ram_update_header_ecc(prz);
 373 
 374         return unlikely(ret) ? ret : count;
 375 }
 376 
 377 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 378 {
 379         return prz->old_log_size;
 380 }
 381 
 382 void *persistent_ram_old(struct persistent_ram_zone *prz)
 383 {
 384         return prz->old_log;
 385 }
 386 
 387 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 388 {
 389         kfree(prz->old_log);
 390         prz->old_log = NULL;
 391         prz->old_log_size = 0;
 392 }
 393 
 394 void persistent_ram_zap(struct persistent_ram_zone *prz)
 395 {
 396         atomic_set(&prz->buffer->start, 0);
 397         atomic_set(&prz->buffer->size, 0);
 398         persistent_ram_update_header_ecc(prz);
 399 }
 400 
 401 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 402                 unsigned int memtype)
 403 {
 404         struct page **pages;
 405         phys_addr_t page_start;
 406         unsigned int page_count;
 407         pgprot_t prot;
 408         unsigned int i;
 409         void *vaddr;
 410 
 411         page_start = start - offset_in_page(start);
 412         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 413 
 414         if (memtype)
 415                 prot = pgprot_noncached(PAGE_KERNEL);
 416         else
 417                 prot = pgprot_writecombine(PAGE_KERNEL);
 418 
 419         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
 420         if (!pages) {
 421                 pr_err("%s: Failed to allocate array for %u pages\n",
 422                        __func__, page_count);
 423                 return NULL;
 424         }
 425 
 426         for (i = 0; i < page_count; i++) {
 427                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 428                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 429         }
 430         vaddr = vmap(pages, page_count, VM_MAP, prot);
 431         kfree(pages);
 432 
 433         /*
 434          * Since vmap() uses page granularity, we must add the offset
 435          * into the page here, to get the byte granularity address
 436          * into the mapping to represent the actual "start" location.
 437          */
 438         return vaddr + offset_in_page(start);
 439 }
 440 
 441 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
 442                 unsigned int memtype, char *label)
 443 {
 444         void *va;
 445 
 446         if (!request_mem_region(start, size, label ?: "ramoops")) {
 447                 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
 448                         label ?: "ramoops",
 449                         (unsigned long long)size, (unsigned long long)start);
 450                 return NULL;
 451         }
 452 
 453         if (memtype)
 454                 va = ioremap(start, size);
 455         else
 456                 va = ioremap_wc(start, size);
 457 
 458         /*
 459          * Since request_mem_region() and ioremap() are byte-granularity
 460          * there is no need handle anything special like we do when the
 461          * vmap() case in persistent_ram_vmap() above.
 462          */
 463         return va;
 464 }
 465 
 466 static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 467                 struct persistent_ram_zone *prz, int memtype)
 468 {
 469         prz->paddr = start;
 470         prz->size = size;
 471 
 472         if (pfn_valid(start >> PAGE_SHIFT))
 473                 prz->vaddr = persistent_ram_vmap(start, size, memtype);
 474         else
 475                 prz->vaddr = persistent_ram_iomap(start, size, memtype,
 476                                                   prz->label);
 477 
 478         if (!prz->vaddr) {
 479                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 480                         (unsigned long long)size, (unsigned long long)start);
 481                 return -ENOMEM;
 482         }
 483 
 484         prz->buffer = prz->vaddr;
 485         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 486 
 487         return 0;
 488 }
 489 
 490 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 491                                     struct persistent_ram_ecc_info *ecc_info)
 492 {
 493         int ret;
 494         bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
 495 
 496         ret = persistent_ram_init_ecc(prz, ecc_info);
 497         if (ret) {
 498                 pr_warn("ECC failed %s\n", prz->label);
 499                 return ret;
 500         }
 501 
 502         sig ^= PERSISTENT_RAM_SIG;
 503 
 504         if (prz->buffer->sig == sig) {
 505                 if (buffer_size(prz) == 0) {
 506                         pr_debug("found existing empty buffer\n");
 507                         return 0;
 508                 }
 509 
 510                 if (buffer_size(prz) > prz->buffer_size ||
 511                     buffer_start(prz) > buffer_size(prz)) {
 512                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
 513                                 buffer_size(prz), buffer_start(prz));
 514                         zap = true;
 515                 } else {
 516                         pr_debug("found existing buffer, size %zu, start %zu\n",
 517                                  buffer_size(prz), buffer_start(prz));
 518                         persistent_ram_save_old(prz);
 519                 }
 520         } else {
 521                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 522                          prz->buffer->sig);
 523                 prz->buffer->sig = sig;
 524                 zap = true;
 525         }
 526 
 527         /* Reset missing, invalid, or single-use memory area. */
 528         if (zap)
 529                 persistent_ram_zap(prz);
 530 
 531         return 0;
 532 }
 533 
 534 void persistent_ram_free(struct persistent_ram_zone *prz)
 535 {
 536         if (!prz)
 537                 return;
 538 
 539         if (prz->vaddr) {
 540                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 541                         /* We must vunmap() at page-granularity. */
 542                         vunmap(prz->vaddr - offset_in_page(prz->paddr));
 543                 } else {
 544                         iounmap(prz->vaddr);
 545                         release_mem_region(prz->paddr, prz->size);
 546                 }
 547                 prz->vaddr = NULL;
 548         }
 549         if (prz->rs_decoder) {
 550                 free_rs(prz->rs_decoder);
 551                 prz->rs_decoder = NULL;
 552         }
 553         kfree(prz->ecc_info.par);
 554         prz->ecc_info.par = NULL;
 555 
 556         persistent_ram_free_old(prz);
 557         kfree(prz->label);
 558         kfree(prz);
 559 }
 560 
 561 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 562                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
 563                         unsigned int memtype, u32 flags, char *label)
 564 {
 565         struct persistent_ram_zone *prz;
 566         int ret = -ENOMEM;
 567 
 568         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 569         if (!prz) {
 570                 pr_err("failed to allocate persistent ram zone\n");
 571                 goto err;
 572         }
 573 
 574         /* Initialize general buffer state. */
 575         raw_spin_lock_init(&prz->buffer_lock);
 576         prz->flags = flags;
 577         prz->label = kstrdup(label, GFP_KERNEL);
 578 
 579         ret = persistent_ram_buffer_map(start, size, prz, memtype);
 580         if (ret)
 581                 goto err;
 582 
 583         ret = persistent_ram_post_init(prz, sig, ecc_info);
 584         if (ret)
 585                 goto err;
 586 
 587         pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
 588                 prz->label, prz->size, (unsigned long long)prz->paddr,
 589                 sizeof(*prz->buffer), prz->buffer_size,
 590                 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
 591                 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
 592 
 593         return prz;
 594 err:
 595         persistent_ram_free(prz);
 596         return ERR_PTR(ret);
 597 }