fs/pstore/ram_core.c

   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[];
  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(c > prz->buffer_size)) {
 352                 s += c - prz->buffer_size;
 353                 c = prz->buffer_size;
 354         }
 355
 356         buffer_size_add(prz, c);
 357
 358         start = buffer_start_add(prz, c);
 359
 360         rem = prz->buffer_size - start;
 361         if (unlikely(rem < c)) {
 362                 ret = persistent_ram_update_user(prz, s, start, rem);
 363                 s += rem;
 364                 c -= rem;
 365                 start = 0;
 366         }
 367         if (likely(!ret))
 368                 ret = persistent_ram_update_user(prz, s, start, c);
 369
 370         persistent_ram_update_header_ecc(prz);
 371
 372         return unlikely(ret) ? ret : count;
 373 }
 374
 375 size_t persistent_ram_old_size(struct persistent_ram_zone *prz)
 376 {
 377         return prz->old_log_size;
 378 }
 379
 380 void *persistent_ram_old(struct persistent_ram_zone *prz)
 381 {
 382         return prz->old_log;
 383 }
 384
 385 void persistent_ram_free_old(struct persistent_ram_zone *prz)
 386 {
 387         kfree(prz->old_log);
 388         prz->old_log = NULL;
 389         prz->old_log_size = 0;
 390 }
 391
 392 void persistent_ram_zap(struct persistent_ram_zone *prz)
 393 {
 394         atomic_set(&prz->buffer->start, 0);
 395         atomic_set(&prz->buffer->size, 0);
 396         persistent_ram_update_header_ecc(prz);
 397 }
 398
 399 static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 400                 unsigned int memtype)
 401 {
 402         struct page **pages;
 403         phys_addr_t page_start;
 404         unsigned int page_count;
 405         pgprot_t prot;
 406         unsigned int i;
 407         void *vaddr;
 408
 409         page_start = start - offset_in_page(start);
 410         page_count = DIV_ROUND_UP(size + offset_in_page(start), PAGE_SIZE);
 411
 412         if (memtype)
 413                 prot = pgprot_noncached(PAGE_KERNEL);
 414         else
 415                 prot = pgprot_writecombine(PAGE_KERNEL);
 416
 417         pages = kmalloc_array(page_count, sizeof(struct page *), GFP_KERNEL);
 418         if (!pages) {
 419                 pr_err("%s: Failed to allocate array for %u pages\n",
 420                        __func__, page_count);
 421                 return NULL;
 422         }
 423
 424         for (i = 0; i < page_count; i++) {
 425                 phys_addr_t addr = page_start + i * PAGE_SIZE;
 426                 pages[i] = pfn_to_page(addr >> PAGE_SHIFT);
 427         }
 428         vaddr = vmap(pages, page_count, VM_MAP, prot);
 429         kfree(pages);
 430
 431         /*
 432          * Since vmap() uses page granularity, we must add the offset
 433          * into the page here, to get the byte granularity address
 434          * into the mapping to represent the actual "start" location.
 435          */
 436         return vaddr + offset_in_page(start);
 437 }
 438
 439 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
 440                 unsigned int memtype, char *label)
 441 {
 442         void *va;
 443
 444         if (!request_mem_region(start, size, label ?: "ramoops")) {
 445                 pr_err("request mem region (%s 0x%llx@0x%llx) failed\n",
 446                         label ?: "ramoops",
 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                                                   prz->label);
 475
 476         if (!prz->vaddr) {
 477                 pr_err("%s: Failed to map 0x%llx pages at 0x%llx\n", __func__,
 478                         (unsigned long long)size, (unsigned long long)start);
 479                 return -ENOMEM;
 480         }
 481
 482         prz->buffer = prz->vaddr;
 483         prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 484
 485         return 0;
 486 }
 487
 488 static int persistent_ram_post_init(struct persistent_ram_zone *prz, u32 sig,
 489                                     struct persistent_ram_ecc_info *ecc_info)
 490 {
 491         int ret;
 492         bool zap = !!(prz->flags & PRZ_FLAG_ZAP_OLD);
 493
 494         ret = persistent_ram_init_ecc(prz, ecc_info);
 495         if (ret) {
 496                 pr_warn("ECC failed %s\n", prz->label);
 497                 return ret;
 498         }
 499
 500         sig ^= PERSISTENT_RAM_SIG;
 501
 502         if (prz->buffer->sig == sig) {
 503                 if (buffer_size(prz) == 0) {
 504                         pr_debug("found existing empty buffer\n");
 505                         return 0;
 506                 }
 507
 508                 if (buffer_size(prz) > prz->buffer_size ||
 509                     buffer_start(prz) > buffer_size(prz)) {
 510                         pr_info("found existing invalid buffer, size %zu, start %zu\n",
 511                                 buffer_size(prz), buffer_start(prz));
 512                         zap = true;
 513                 } else {
 514                         pr_debug("found existing buffer, size %zu, start %zu\n",
 515                                  buffer_size(prz), buffer_start(prz));
 516                         persistent_ram_save_old(prz);
 517                 }
 518         } else {
 519                 pr_debug("no valid data in buffer (sig = 0x%08x)\n",
 520                          prz->buffer->sig);
 521                 prz->buffer->sig = sig;
 522                 zap = true;
 523         }
 524
 525         /* Reset missing, invalid, or single-use memory area. */
 526         if (zap)
 527                 persistent_ram_zap(prz);
 528
 529         return 0;
 530 }
 531
 532 void persistent_ram_free(struct persistent_ram_zone *prz)
 533 {
 534         if (!prz)
 535                 return;
 536
 537         if (prz->vaddr) {
 538                 if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
 539                         /* We must vunmap() at page-granularity. */
 540                         vunmap(prz->vaddr - offset_in_page(prz->paddr));
 541                 } else {
 542                         iounmap(prz->vaddr);
 543                         release_mem_region(prz->paddr, prz->size);
 544                 }
 545                 prz->vaddr = NULL;
 546         }
 547         if (prz->rs_decoder) {
 548                 free_rs(prz->rs_decoder);
 549                 prz->rs_decoder = NULL;
 550         }
 551         kfree(prz->ecc_info.par);
 552         prz->ecc_info.par = NULL;
 553
 554         persistent_ram_free_old(prz);
 555         kfree(prz->label);
 556         kfree(prz);
 557 }
 558
 559 struct persistent_ram_zone *persistent_ram_new(phys_addr_t start, size_t size,
 560                         u32 sig, struct persistent_ram_ecc_info *ecc_info,
 561                         unsigned int memtype, u32 flags, char *label)
 562 {
 563         struct persistent_ram_zone *prz;
 564         int ret = -ENOMEM;
 565
 566         prz = kzalloc(sizeof(struct persistent_ram_zone), GFP_KERNEL);
 567         if (!prz) {
 568                 pr_err("failed to allocate persistent ram zone\n");
 569                 goto err;
 570         }
 571
 572         /* Initialize general buffer state. */
 573         raw_spin_lock_init(&prz->buffer_lock);
 574         prz->flags = flags;
 575         prz->label = kstrdup(label, GFP_KERNEL);
 576
 577         ret = persistent_ram_buffer_map(start, size, prz, memtype);
 578         if (ret)
 579                 goto err;
 580
 581         ret = persistent_ram_post_init(prz, sig, ecc_info);
 582         if (ret)
 583                 goto err;
 584
 585         pr_debug("attached %s 0x%zx@0x%llx: %zu header, %zu data, %zu ecc (%d/%d)\n",
 586                 prz->label, prz->size, (unsigned long long)prz->paddr,
 587                 sizeof(*prz->buffer), prz->buffer_size,
 588                 prz->size - sizeof(*prz->buffer) - prz->buffer_size,
 589                 prz->ecc_info.ecc_size, prz->ecc_info.block_size);
 590
 591         return prz;
 592 err:
 593         persistent_ram_free(prz);
 594         return ERR_PTR(ret);
 595 }