drivers/mtd/ubi/io.c

   1 /*
   2  * Copyright (c) International Business Machines Corp., 2006
   3  * Copyright (c) Nokia Corporation, 2006, 2007
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
  13  * the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  18  *
  19  * Author: Artem Bityutskiy (Битюцкий Артём)
  20  */
  21
  22 /*
  23  * UBI input/output unit.
  24  *
  25  * This unit provides a uniform way to work with all kinds of the underlying
  26  * MTD devices. It also implements handy functions for reading and writing UBI
  27  * headers.
  28  *
  29  * We are trying to have a paranoid mindset and not to trust to what we read
  30  * from the flash media in order to be more secure and robust. So this unit
  31  * validates every single header it reads from the flash media.
  32  *
  33  * Some words about how the eraseblock headers are stored.
  34  *
  35  * The erase counter header is always stored at offset zero. By default, the
  36  * VID header is stored after the EC header at the closest aligned offset
  37  * (i.e. aligned to the minimum I/O unit size). Data starts next to the VID
  38  * header at the closest aligned offset. But this default layout may be
  39  * changed. For example, for different reasons (e.g., optimization) UBI may be
  40  * asked to put the VID header at further offset, and even at an unaligned
  41  * offset. Of course, if the offset of the VID header is unaligned, UBI adds
  42  * proper padding in front of it. Data offset may also be changed but it has to
  43  * be aligned.
  44  *
  45  * About minimal I/O units. In general, UBI assumes flash device model where
  46  * there is only one minimal I/O unit size. E.g., in case of NOR flash it is 1,
  47  * in case of NAND flash it is a NAND page, etc. This is reported by MTD in the
  48  * @ubi->mtd->writesize field. But as an exception, UBI admits of using another
  49  * (smaller) minimal I/O unit size for EC and VID headers to make it possible
  50  * to do different optimizations.
  51  *
  52  * This is extremely useful in case of NAND flashes which admit of several
  53  * write operations to one NAND page. In this case UBI can fit EC and VID
  54  * headers at one NAND page. Thus, UBI may use "sub-page" size as the minimal
  55  * I/O unit for the headers (the @ubi->hdrs_min_io_size field). But it still
  56  * reports NAND page size (@ubi->min_io_size) as a minimal I/O unit for the UBI
  57  * users.
  58  *
  59  * Example: some Samsung NANDs with 2KiB pages allow 4x 512-byte writes, so
  60  * although the minimal I/O unit is 2K, UBI uses 512 bytes for EC and VID
  61  * headers.
  62  *
  63  * Q: why not just to treat sub-page as a minimal I/O unit of this flash
  64  * device, e.g., make @ubi->min_io_size = 512 in the example above?
  65  *
  66  * A: because when writing a sub-page, MTD still writes a full 2K page but the
  67  * bytes which are no relevant to the sub-page are 0xFF. So, basically, writing
  68  * 4x512 sub-pages is 4 times slower then writing one 2KiB NAND page. Thus, we
  69  * prefer to use sub-pages only for EV and VID headers.
  70  *
  71  * As it was noted above, the VID header may start at a non-aligned offset.
  72  * For example, in case of a 2KiB page NAND flash with a 512 bytes sub-page,
  73  * the VID header may reside at offset 1984 which is the last 64 bytes of the
  74  * last sub-page (EC header is always at offset zero). This causes some
  75  * difficulties when reading and writing VID headers.
  76  *
  77  * Suppose we have a 64-byte buffer and we read a VID header at it. We change
  78  * the data and want to write this VID header out. As we can only write in
  79  * 512-byte chunks, we have to allocate one more buffer and copy our VID header
  80  * to offset 448 of this buffer.
  81  *
  82  * The I/O unit does the following trick in order to avoid this extra copy.
  83  * It always allocates a @ubi->vid_hdr_alsize bytes buffer for the VID header
  84  * and returns a pointer to offset @ubi->vid_hdr_shift of this buffer. When the
  85  * VID header is being written out, it shifts the VID header pointer back and
  86  * writes the whole sub-page.
  87  */
  88
  89 #include <linux/crc32.h>
  90 #include <linux/err.h>
  91 #include "ubi.h"
  92
  93 #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
  94 static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum);
  95 static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum);
  96 static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
  97                                  const struct ubi_ec_hdr *ec_hdr);
  98 static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum);
  99 static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
 100                                   const struct ubi_vid_hdr *vid_hdr);
 101 static int paranoid_check_all_ff(struct ubi_device *ubi, int pnum, int offset,
 102                                  int len);
 103 #else
 104 #define paranoid_check_not_bad(ubi, pnum) 0
 105 #define paranoid_check_peb_ec_hdr(ubi, pnum)  0
 106 #define paranoid_check_ec_hdr(ubi, pnum, ec_hdr)  0
 107 #define paranoid_check_peb_vid_hdr(ubi, pnum) 0
 108 #define paranoid_check_vid_hdr(ubi, pnum, vid_hdr) 0
 109 #define paranoid_check_all_ff(ubi, pnum, offset, len) 0
 110 #endif
 111
 112 /**
 113  * ubi_io_read - read data from a physical eraseblock.
 114  * @ubi: UBI device description object
 115  * @buf: buffer where to store the read data
 116  * @pnum: physical eraseblock number to read from
 117  * @offset: offset within the physical eraseblock from where to read
 118  * @len: how many bytes to read
 119  *
 120  * This function reads data from offset @offset of physical eraseblock @pnum
 121  * and stores the read data in the @buf buffer. The following return codes are
 122  * possible:
 123  *
 124  * o %0 if all the requested data were successfully read;
 125  * o %UBI_IO_BITFLIPS if all the requested data were successfully read, but
 126  *   correctable bit-flips were detected; this is harmless but may indicate
 127  *   that this eraseblock may become bad soon (but do not have to);
 128  * o %-EBADMSG if the MTD subsystem reported about data integrity problems, for
 129  *   example it can be an ECC error in case of NAND; this most probably means
 130  *   that the data is corrupted;
 131  * o %-EIO if some I/O error occurred;
 132  * o other negative error codes in case of other errors.
 133  */
 134 int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
 135                 int len)
 136 {
 137         int err, retries = 0;
 138         size_t read;
 139         loff_t addr;
 140
 141         dbg_io("read %d bytes from PEB %d:%d", len, pnum, offset);
 142
 143         ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
 144         ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
 145         ubi_assert(len > 0);
 146
 147         err = paranoid_check_not_bad(ubi, pnum);
 148         if (err)
 149                 return err > 0 ? -EINVAL : err;
 150
 151         addr = (loff_t)pnum * ubi->peb_size + offset;
 152 retry:
 153         err = ubi->mtd->read(ubi->mtd, addr, len, &read, buf);
 154         if (err) {
 155                 if (err == -EUCLEAN) {
 156                         /*
 157                          * -EUCLEAN is reported if there was a bit-flip which
 158                          * was corrected, so this is harmless.
 159                          */
 160                         ubi_msg("fixable bit-flip detected at PEB %d", pnum);
 161                         ubi_assert(len == read);
 162                         return UBI_IO_BITFLIPS;
 163                 }
 164
 165                 if (read != len && retries++ < UBI_IO_RETRIES) {
 166                         dbg_io("error %d while reading %d bytes from PEB %d:%d, "
 167                                "read only %zd bytes, retry",
 168                                err, len, pnum, offset, read);
 169                         yield();
 170                         goto retry;
 171                 }
 172
 173                 ubi_err("error %d while reading %d bytes from PEB %d:%d, "
 174                         "read %zd bytes", err, len, pnum, offset, read);
 175                 ubi_dbg_dump_stack();
 176
 177                 /*
 178                  * The driver should never return -EBADMSG if it failed to read
 179                  * all the requested data. But some buggy drivers might do
 180                  * this, so we change it to -EIO.
 181                  */
 182                 if (read != len && err == -EBADMSG) {
 183                         ubi_assert(0);
 184                         err = -EIO;
 185                 }
 186         } else {
 187                 ubi_assert(len == read);
 188
 189                 if (ubi_dbg_is_bitflip()) {
 190                         dbg_msg("bit-flip (emulated)");
 191                         err = UBI_IO_BITFLIPS;
 192                 }
 193         }
 194
 195         return err;
 196 }
 197
 198 /**
 199  * ubi_io_write - write data to a physical eraseblock.
 200  * @ubi: UBI device description object
 201  * @buf: buffer with the data to write
 202  * @pnum: physical eraseblock number to write to
 203  * @offset: offset within the physical eraseblock where to write
 204  * @len: how many bytes to write
 205  *
 206  * This function writes @len bytes of data from buffer @buf to offset @offset
 207  * of physical eraseblock @pnum. If all the data were successfully written,
 208  * zero is returned. If an error occurred, this function returns a negative
 209  * error code. If %-EIO is returned, the physical eraseblock most probably went
 210  * bad.
 211  *
 212  * Note, in case of an error, it is possible that something was still written
 213  * to the flash media, but may be some garbage.
 214  */
 215 int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
 216                  int len)
 217 {
 218         int err;
 219         size_t written;
 220         loff_t addr;
 221
 222         dbg_io("write %d bytes to PEB %d:%d", len, pnum, offset);
 223
 224         ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
 225         ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
 226         ubi_assert(offset % ubi->hdrs_min_io_size == 0);
 227         ubi_assert(len > 0 && len % ubi->hdrs_min_io_size == 0);
 228
 229         if (ubi->ro_mode) {
 230                 ubi_err("read-only mode");
 231                 return -EROFS;
 232         }
 233
 234         /* The below has to be compiled out if paranoid checks are disabled */
 235
 236         err = paranoid_check_not_bad(ubi, pnum);
 237         if (err)
 238                 return err > 0 ? -EINVAL : err;
 239
 240         /* The area we are writing to has to contain all 0xFF bytes */
 241         err = paranoid_check_all_ff(ubi, pnum, offset, len);
 242         if (err)
 243                 return err > 0 ? -EINVAL : err;
 244
 245         if (offset >= ubi->leb_start) {
 246                 /*
 247                  * We write to the data area of the physical eraseblock. Make
 248                  * sure it has valid EC and VID headers.
 249                  */
 250                 err = paranoid_check_peb_ec_hdr(ubi, pnum);
 251                 if (err)
 252                         return err > 0 ? -EINVAL : err;
 253                 err = paranoid_check_peb_vid_hdr(ubi, pnum);
 254                 if (err)
 255                         return err > 0 ? -EINVAL : err;
 256         }
 257
 258         if (ubi_dbg_is_write_failure()) {
 259                 dbg_err("cannot write %d bytes to PEB %d:%d "
 260                         "(emulated)", len, pnum, offset);
 261                 ubi_dbg_dump_stack();
 262                 return -EIO;
 263         }
 264
 265         addr = (loff_t)pnum * ubi->peb_size + offset;
 266         err = ubi->mtd->write(ubi->mtd, addr, len, &written, buf);
 267         if (err) {
 268                 ubi_err("error %d while writing %d bytes to PEB %d:%d, written"
 269                         " %zd bytes", err, len, pnum, offset, written);
 270                 ubi_dbg_dump_stack();
 271         } else
 272                 ubi_assert(written == len);
 273
 274         return err;
 275 }
 276
 277 /**
 278  * erase_callback - MTD erasure call-back.
 279  * @ei: MTD erase information object.
 280  *
 281  * Note, even though MTD erase interface is asynchronous, all the current
 282  * implementations are synchronous anyway.
 283  */
 284 static void erase_callback(struct erase_info *ei)
 285 {
 286         wake_up_interruptible((wait_queue_head_t *)ei->priv);
 287 }
 288
 289 /**
 290  * do_sync_erase - synchronously erase a physical eraseblock.
 291  * @ubi: UBI device description object
 292  * @pnum: the physical eraseblock number to erase
 293  *
 294  * This function synchronously erases physical eraseblock @pnum and returns
 295  * zero in case of success and a negative error code in case of failure. If
 296  * %-EIO is returned, the physical eraseblock most probably went bad.
 297  */
 298 static int do_sync_erase(struct ubi_device *ubi, int pnum)
 299 {
 300         int err, retries = 0;
 301         struct erase_info ei;
 302         wait_queue_head_t wq;
 303
 304         dbg_io("erase PEB %d", pnum);
 305
 306 retry:
 307         init_waitqueue_head(&wq);
 308         memset(&ei, 0, sizeof(struct erase_info));
 309
 310         ei.mtd      = ubi->mtd;
 311         ei.addr     = (loff_t)pnum * ubi->peb_size;
 312         ei.len      = ubi->peb_size;
 313         ei.callback = erase_callback;
 314         ei.priv     = (unsigned long)&wq;
 315
 316         err = ubi->mtd->erase(ubi->mtd, &ei);
 317         if (err) {
 318                 if (retries++ < UBI_IO_RETRIES) {
 319                         dbg_io("error %d while erasing PEB %d, retry",
 320                                err, pnum);
 321                         yield();
 322                         goto retry;
 323                 }
 324                 ubi_err("cannot erase PEB %d, error %d", pnum, err);
 325                 ubi_dbg_dump_stack();
 326                 return err;
 327         }
 328
 329         err = wait_event_interruptible(wq, ei.state == MTD_ERASE_DONE ||
 330                                            ei.state == MTD_ERASE_FAILED);
 331         if (err) {
 332                 ubi_err("interrupted PEB %d erasure", pnum);
 333                 return -EINTR;
 334         }
 335
 336         if (ei.state == MTD_ERASE_FAILED) {
 337                 if (retries++ < UBI_IO_RETRIES) {
 338                         dbg_io("error while erasing PEB %d, retry", pnum);
 339                         yield();
 340                         goto retry;
 341                 }
 342                 ubi_err("cannot erase PEB %d", pnum);
 343                 ubi_dbg_dump_stack();
 344                 return -EIO;
 345         }
 346
 347         err = paranoid_check_all_ff(ubi, pnum, 0, ubi->peb_size);
 348         if (err)
 349                 return err > 0 ? -EINVAL : err;
 350
 351         if (ubi_dbg_is_erase_failure() && !err) {
 352                 dbg_err("cannot erase PEB %d (emulated)", pnum);
 353                 return -EIO;
 354         }
 355
 356         return 0;
 357 }
 358
 359 /**
 360  * check_pattern - check if buffer contains only a certain byte pattern.
 361  * @buf: buffer to check
 362  * @patt: the pattern to check
 363  * @size: buffer size in bytes
 364  *
 365  * This function returns %1 in there are only @patt bytes in @buf, and %0 if
 366  * something else was also found.
 367  */
 368 static int check_pattern(const void *buf, uint8_t patt, int size)
 369 {
 370         int i;
 371
 372         for (i = 0; i < size; i++)
 373                 if (((const uint8_t *)buf)[i] != patt)
 374                         return 0;
 375         return 1;
 376 }
 377
 378 /* Patterns to write to a physical eraseblock when torturing it */
 379 static uint8_t patterns[] = {0xa5, 0x5a, 0x0};
 380
 381 /**
 382  * torture_peb - test a supposedly bad physical eraseblock.
 383  * @ubi: UBI device description object
 384  * @pnum: the physical eraseblock number to test
 385  *
 386  * This function returns %-EIO if the physical eraseblock did not pass the
 387  * test, a positive number of erase operations done if the test was
 388  * successfully passed, and other negative error codes in case of other errors.
 389  */
 390 static int torture_peb(struct ubi_device *ubi, int pnum)
 391 {
 392         int err, i, patt_count;
 393
 394         patt_count = ARRAY_SIZE(patterns);
 395         ubi_assert(patt_count > 0);
 396
 397         mutex_lock(&ubi->buf_mutex);
 398         for (i = 0; i < patt_count; i++) {
 399                 err = do_sync_erase(ubi, pnum);
 400                 if (err)
 401                         goto out;
 402
 403                 /* Make sure the PEB contains only 0xFF bytes */
 404                 err = ubi_io_read(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
 405                 if (err)
 406                         goto out;
 407
 408                 err = check_pattern(ubi->peb_buf1, 0xFF, ubi->peb_size);
 409                 if (err == 0) {
 410                         ubi_err("erased PEB %d, but a non-0xFF byte found",
 411                                 pnum);
 412                         err = -EIO;
 413                         goto out;
 414                 }
 415
 416                 /* Write a pattern and check it */
 417                 memset(ubi->peb_buf1, patterns[i], ubi->peb_size);
 418                 err = ubi_io_write(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
 419                 if (err)
 420                         goto out;
 421
 422                 memset(ubi->peb_buf1, ~patterns[i], ubi->peb_size);
 423                 err = ubi_io_read(ubi, ubi->peb_buf1, pnum, 0, ubi->peb_size);
 424                 if (err)
 425                         goto out;
 426
 427                 err = check_pattern(ubi->peb_buf1, patterns[i], ubi->peb_size);
 428                 if (err == 0) {
 429                         ubi_err("pattern %x checking failed for PEB %d",
 430                                 patterns[i], pnum);
 431                         err = -EIO;
 432                         goto out;
 433                 }
 434         }
 435
 436         err = patt_count;
 437
 438 out:
 439         mutex_unlock(&ubi->buf_mutex);
 440         if (err == UBI_IO_BITFLIPS || err == -EBADMSG) {
 441                 /*
 442                  * If a bit-flip or data integrity error was detected, the test
 443                  * has not passed because it happened on a freshly erased
 444                  * physical eraseblock which means something is wrong with it.
 445                  */
 446                 ubi_err("read problems on freshly erased PEB %d, must be bad",
 447                         pnum);
 448                 err = -EIO;
 449         }
 450         return err;
 451 }
 452
 453 /**
 454  * ubi_io_sync_erase - synchronously erase a physical eraseblock.
 455  * @ubi: UBI device description object
 456  * @pnum: physical eraseblock number to erase
 457  * @torture: if this physical eraseblock has to be tortured
 458  *
 459  * This function synchronously erases physical eraseblock @pnum. If @torture
 460  * flag is not zero, the physical eraseblock is checked by means of writing
 461  * different patterns to it and reading them back. If the torturing is enabled,
 462  * the physical eraseblock is erased more then once.
 463  *
 464  * This function returns the number of erasures made in case of success, %-EIO
 465  * if the erasure failed or the torturing test failed, and other negative error
 466  * codes in case of other errors. Note, %-EIO means that the physical
 467  * eraseblock is bad.
 468  */
 469 int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture)
 470 {
 471         int err, ret = 0;
 472
 473         ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
 474
 475         err = paranoid_check_not_bad(ubi, pnum);
 476         if (err != 0)
 477                 return err > 0 ? -EINVAL : err;
 478
 479         if (ubi->ro_mode) {
 480                 ubi_err("read-only mode");
 481                 return -EROFS;
 482         }
 483
 484         if (torture) {
 485                 ret = torture_peb(ubi, pnum);
 486                 if (ret < 0)
 487                         return ret;
 488         }
 489
 490         err = do_sync_erase(ubi, pnum);
 491         if (err)
 492                 return err;
 493
 494         return ret + 1;
 495 }
 496
 497 /**
 498  * ubi_io_is_bad - check if a physical eraseblock is bad.
 499  * @ubi: UBI device description object
 500  * @pnum: the physical eraseblock number to check
 501  *
 502  * This function returns a positive number if the physical eraseblock is bad,
 503  * zero if not, and a negative error code if an error occurred.
 504  */
 505 int ubi_io_is_bad(const struct ubi_device *ubi, int pnum)
 506 {
 507         struct mtd_info *mtd = ubi->mtd;
 508
 509         ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
 510
 511         if (ubi->bad_allowed) {
 512                 int ret;
 513
 514                 ret = mtd->block_isbad(mtd, (loff_t)pnum * ubi->peb_size);
 515                 if (ret < 0)
 516                         ubi_err("error %d while checking if PEB %d is bad",
 517                                 ret, pnum);
 518                 else if (ret)
 519                         dbg_io("PEB %d is bad", pnum);
 520                 return ret;
 521         }
 522
 523         return 0;
 524 }
 525
 526 /**
 527  * ubi_io_mark_bad - mark a physical eraseblock as bad.
 528  * @ubi: UBI device description object
 529  * @pnum: the physical eraseblock number to mark
 530  *
 531  * This function returns zero in case of success and a negative error code in
 532  * case of failure.
 533  */
 534 int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum)
 535 {
 536         int err;
 537         struct mtd_info *mtd = ubi->mtd;
 538
 539         ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
 540
 541         if (ubi->ro_mode) {
 542                 ubi_err("read-only mode");
 543                 return -EROFS;
 544         }
 545
 546         if (!ubi->bad_allowed)
 547                 return 0;
 548
 549         err = mtd->block_markbad(mtd, (loff_t)pnum * ubi->peb_size);
 550         if (err)
 551                 ubi_err("cannot mark PEB %d bad, error %d", pnum, err);
 552         return err;
 553 }
 554
 555 /**
 556  * validate_ec_hdr - validate an erase counter header.
 557  * @ubi: UBI device description object
 558  * @ec_hdr: the erase counter header to check
 559  *
 560  * This function returns zero if the erase counter header is OK, and %1 if
 561  * not.
 562  */
 563 static int validate_ec_hdr(const struct ubi_device *ubi,
 564                            const struct ubi_ec_hdr *ec_hdr)
 565 {
 566         long long ec;
 567         int vid_hdr_offset, leb_start;
 568
 569         ec = be64_to_cpu(ec_hdr->ec);
 570         vid_hdr_offset = be32_to_cpu(ec_hdr->vid_hdr_offset);
 571         leb_start = be32_to_cpu(ec_hdr->data_offset);
 572
 573         if (ec_hdr->version != UBI_VERSION) {
 574                 ubi_err("node with incompatible UBI version found: "
 575                         "this UBI version is %d, image version is %d",
 576                         UBI_VERSION, (int)ec_hdr->version);
 577                 goto bad;
 578         }
 579
 580         if (vid_hdr_offset != ubi->vid_hdr_offset) {
 581                 ubi_err("bad VID header offset %d, expected %d",
 582                         vid_hdr_offset, ubi->vid_hdr_offset);
 583                 goto bad;
 584         }
 585
 586         if (leb_start != ubi->leb_start) {
 587                 ubi_err("bad data offset %d, expected %d",
 588                         leb_start, ubi->leb_start);
 589                 goto bad;
 590         }
 591
 592         if (ec < 0 || ec > UBI_MAX_ERASECOUNTER) {
 593                 ubi_err("bad erase counter %lld", ec);
 594                 goto bad;
 595         }
 596
 597         return 0;
 598
 599 bad:
 600         ubi_err("bad EC header");
 601         ubi_dbg_dump_ec_hdr(ec_hdr);
 602         ubi_dbg_dump_stack();
 603         return 1;
 604 }
 605
 606 /**
 607  * ubi_io_read_ec_hdr - read and check an erase counter header.
 608  * @ubi: UBI device description object
 609  * @pnum: physical eraseblock to read from
 610  * @ec_hdr: a &struct ubi_ec_hdr object where to store the read erase counter
 611  * header
 612  * @verbose: be verbose if the header is corrupted or was not found
 613  *
 614  * This function reads erase counter header from physical eraseblock @pnum and
 615  * stores it in @ec_hdr. This function also checks CRC checksum of the read
 616  * erase counter header. The following codes may be returned:
 617  *
 618  * o %0 if the CRC checksum is correct and the header was successfully read;
 619  * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
 620  *   and corrected by the flash driver; this is harmless but may indicate that
 621  *   this eraseblock may become bad soon (but may be not);
 622  * o %UBI_IO_BAD_EC_HDR if the erase counter header is corrupted (a CRC error);
 623  * o %UBI_IO_PEB_EMPTY if the physical eraseblock is empty;
 624  * o a negative error code in case of failure.
 625  */
 626 int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
 627                        struct ubi_ec_hdr *ec_hdr, int verbose)
 628 {
 629         int err, read_err = 0;
 630         uint32_t crc, magic, hdr_crc;
 631
 632         dbg_io("read EC header from PEB %d", pnum);
 633         ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
 634
 635         err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
 636         if (err) {
 637                 if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
 638                         return err;
 639
 640                 /*
 641                  * We read all the data, but either a correctable bit-flip
 642                  * occurred, or MTD reported about some data integrity error,
 643                  * like an ECC error in case of NAND. The former is harmless,
 644                  * the later may mean that the read data is corrupted. But we
 645                  * have a CRC check-sum and we will detect this. If the EC
 646                  * header is still OK, we just report this as there was a
 647                  * bit-flip.
 648                  */
 649                 read_err = err;
 650         }
 651
 652         magic = be32_to_cpu(ec_hdr->magic);
 653         if (magic != UBI_EC_HDR_MAGIC) {
 654                 /*
 655                  * The magic field is wrong. Let's check if we have read all
 656                  * 0xFF. If yes, this physical eraseblock is assumed to be
 657                  * empty.
 658                  *
 659                  * But if there was a read error, we do not test it for all
 660                  * 0xFFs. Even if it does contain all 0xFFs, this error
 661                  * indicates that something is still wrong with this physical
 662                  * eraseblock and we anyway cannot treat it as empty.
 663                  */
 664                 if (read_err != -EBADMSG &&
 665                     check_pattern(ec_hdr, 0xFF, UBI_EC_HDR_SIZE)) {
 666                         /* The physical eraseblock is supposedly empty */
 667
 668                         /*
 669                          * The below is just a paranoid check, it has to be
 670                          * compiled out if paranoid checks are disabled.
 671                          */
 672                         err = paranoid_check_all_ff(ubi, pnum, 0,
 673                                                     ubi->peb_size);
 674                         if (err)
 675                                 return err > 0 ? UBI_IO_BAD_EC_HDR : err;
 676
 677                         if (verbose)
 678                                 ubi_warn("no EC header found at PEB %d, "
 679                                          "only 0xFF bytes", pnum);
 680                         return UBI_IO_PEB_EMPTY;
 681                 }
 682
 683                 /*
 684                  * This is not a valid erase counter header, and these are not
 685                  * 0xFF bytes. Report that the header is corrupted.
 686                  */
 687                 if (verbose) {
 688                         ubi_warn("bad magic number at PEB %d: %08x instead of "
 689                                  "%08x", pnum, magic, UBI_EC_HDR_MAGIC);
 690                         ubi_dbg_dump_ec_hdr(ec_hdr);
 691                 }
 692                 return UBI_IO_BAD_EC_HDR;
 693         }
 694
 695         crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
 696         hdr_crc = be32_to_cpu(ec_hdr->hdr_crc);
 697
 698         if (hdr_crc != crc) {
 699                 if (verbose) {
 700                         ubi_warn("bad EC header CRC at PEB %d, calculated %#08x,"
 701                                  " read %#08x", pnum, crc, hdr_crc);
 702                         ubi_dbg_dump_ec_hdr(ec_hdr);
 703                 }
 704                 return UBI_IO_BAD_EC_HDR;
 705         }
 706
 707         /* And of course validate what has just been read from the media */
 708         err = validate_ec_hdr(ubi, ec_hdr);
 709         if (err) {
 710                 ubi_err("validation failed for PEB %d", pnum);
 711                 return -EINVAL;
 712         }
 713
 714         return read_err ? UBI_IO_BITFLIPS : 0;
 715 }
 716
 717 /**
 718  * ubi_io_write_ec_hdr - write an erase counter header.
 719  * @ubi: UBI device description object
 720  * @pnum: physical eraseblock to write to
 721  * @ec_hdr: the erase counter header to write
 722  *
 723  * This function writes erase counter header described by @ec_hdr to physical
 724  * eraseblock @pnum. It also fills most fields of @ec_hdr before writing, so
 725  * the caller do not have to fill them. Callers must only fill the @ec_hdr->ec
 726  * field.
 727  *
 728  * This function returns zero in case of success and a negative error code in
 729  * case of failure. If %-EIO is returned, the physical eraseblock most probably
 730  * went bad.
 731  */
 732 int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
 733                         struct ubi_ec_hdr *ec_hdr)
 734 {
 735         int err;
 736         uint32_t crc;
 737
 738         dbg_io("write EC header to PEB %d", pnum);
 739         ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
 740
 741         ec_hdr->magic = cpu_to_be32(UBI_EC_HDR_MAGIC);
 742         ec_hdr->version = UBI_VERSION;
 743         ec_hdr->vid_hdr_offset = cpu_to_be32(ubi->vid_hdr_offset);
 744         ec_hdr->data_offset = cpu_to_be32(ubi->leb_start);
 745         crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
 746         ec_hdr->hdr_crc = cpu_to_be32(crc);
 747
 748         err = paranoid_check_ec_hdr(ubi, pnum, ec_hdr);
 749         if (err)
 750                 return -EINVAL;
 751
 752         err = ubi_io_write(ubi, ec_hdr, pnum, 0, ubi->ec_hdr_alsize);
 753         return err;
 754 }
 755
 756 /**
 757  * validate_vid_hdr - validate a volume identifier header.
 758  * @ubi: UBI device description object
 759  * @vid_hdr: the volume identifier header to check
 760  *
 761  * This function checks that data stored in the volume identifier header
 762  * @vid_hdr. Returns zero if the VID header is OK and %1 if not.
 763  */
 764 static int validate_vid_hdr(const struct ubi_device *ubi,
 765                             const struct ubi_vid_hdr *vid_hdr)
 766 {
 767         int vol_type = vid_hdr->vol_type;
 768         int copy_flag = vid_hdr->copy_flag;
 769         int vol_id = be32_to_cpu(vid_hdr->vol_id);
 770         int lnum = be32_to_cpu(vid_hdr->lnum);
 771         int compat = vid_hdr->compat;
 772         int data_size = be32_to_cpu(vid_hdr->data_size);
 773         int used_ebs = be32_to_cpu(vid_hdr->used_ebs);
 774         int data_pad = be32_to_cpu(vid_hdr->data_pad);
 775         int data_crc = be32_to_cpu(vid_hdr->data_crc);
 776         int usable_leb_size = ubi->leb_size - data_pad;
 777
 778         if (copy_flag != 0 && copy_flag != 1) {
 779                 dbg_err("bad copy_flag");
 780                 goto bad;
 781         }
 782
 783         if (vol_id < 0 || lnum < 0 || data_size < 0 || used_ebs < 0 ||
 784             data_pad < 0) {
 785                 dbg_err("negative values");
 786                 goto bad;
 787         }
 788
 789         if (vol_id >= UBI_MAX_VOLUMES && vol_id < UBI_INTERNAL_VOL_START) {
 790                 dbg_err("bad vol_id");
 791                 goto bad;
 792         }
 793
 794         if (vol_id < UBI_INTERNAL_VOL_START && compat != 0) {
 795                 dbg_err("bad compat");
 796                 goto bad;
 797         }
 798
 799         if (vol_id >= UBI_INTERNAL_VOL_START && compat != UBI_COMPAT_DELETE &&
 800             compat != UBI_COMPAT_RO && compat != UBI_COMPAT_PRESERVE &&
 801             compat != UBI_COMPAT_REJECT) {
 802                 dbg_err("bad compat");
 803                 goto bad;
 804         }
 805
 806         if (vol_type != UBI_VID_DYNAMIC && vol_type != UBI_VID_STATIC) {
 807                 dbg_err("bad vol_type");
 808                 goto bad;
 809         }
 810
 811         if (data_pad >= ubi->leb_size / 2) {
 812                 dbg_err("bad data_pad");
 813                 goto bad;
 814         }
 815
 816         if (vol_type == UBI_VID_STATIC) {
 817                 /*
 818                  * Although from high-level point of view static volumes may
 819                  * contain zero bytes of data, but no VID headers can contain
 820                  * zero at these fields, because they empty volumes do not have
 821                  * mapped logical eraseblocks.
 822                  */
 823                 if (used_ebs == 0) {
 824                         dbg_err("zero used_ebs");
 825                         goto bad;
 826                 }
 827                 if (data_size == 0) {
 828                         dbg_err("zero data_size");
 829                         goto bad;
 830                 }
 831                 if (lnum < used_ebs - 1) {
 832                         if (data_size != usable_leb_size) {
 833                                 dbg_err("bad data_size");
 834                                 goto bad;
 835                         }
 836                 } else if (lnum == used_ebs - 1) {
 837                         if (data_size == 0) {
 838                                 dbg_err("bad data_size at last LEB");
 839                                 goto bad;
 840                         }
 841                 } else {
 842                         dbg_err("too high lnum");
 843                         goto bad;
 844                 }
 845         } else {
 846                 if (copy_flag == 0) {
 847                         if (data_crc != 0) {
 848                                 dbg_err("non-zero data CRC");
 849                                 goto bad;
 850                         }
 851                         if (data_size != 0) {
 852                                 dbg_err("non-zero data_size");
 853                                 goto bad;
 854                         }
 855                 } else {
 856                         if (data_size == 0) {
 857                                 dbg_err("zero data_size of copy");
 858                                 goto bad;
 859                         }
 860                 }
 861                 if (used_ebs != 0) {
 862                         dbg_err("bad used_ebs");
 863                         goto bad;
 864                 }
 865         }
 866
 867         return 0;
 868
 869 bad:
 870         ubi_err("bad VID header");
 871         ubi_dbg_dump_vid_hdr(vid_hdr);
 872         ubi_dbg_dump_stack();
 873         return 1;
 874 }
 875
 876 /**
 877  * ubi_io_read_vid_hdr - read and check a volume identifier header.
 878  * @ubi: UBI device description object
 879  * @pnum: physical eraseblock number to read from
 880  * @vid_hdr: &struct ubi_vid_hdr object where to store the read volume
 881  * identifier header
 882  * @verbose: be verbose if the header is corrupted or wasn't found
 883  *
 884  * This function reads the volume identifier header from physical eraseblock
 885  * @pnum and stores it in @vid_hdr. It also checks CRC checksum of the read
 886  * volume identifier header. The following codes may be returned:
 887  *
 888  * o %0 if the CRC checksum is correct and the header was successfully read;
 889  * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
 890  *   and corrected by the flash driver; this is harmless but may indicate that
 891  *   this eraseblock may become bad soon;
 892  * o %UBI_IO_BAD_VID_HRD if the volume identifier header is corrupted (a CRC
 893  *   error detected);
 894  * o %UBI_IO_PEB_FREE if the physical eraseblock is free (i.e., there is no VID
 895  *   header there);
 896  * o a negative error code in case of failure.
 897  */
 898 int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
 899                         struct ubi_vid_hdr *vid_hdr, int verbose)
 900 {
 901         int err, read_err = 0;
 902         uint32_t crc, magic, hdr_crc;
 903         void *p;
 904
 905         dbg_io("read VID header from PEB %d", pnum);
 906         ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
 907
 908         p = (char *)vid_hdr - ubi->vid_hdr_shift;
 909         err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
 910                           ubi->vid_hdr_alsize);
 911         if (err) {
 912                 if (err != UBI_IO_BITFLIPS && err != -EBADMSG)
 913                         return err;
 914
 915                 /*
 916                  * We read all the data, but either a correctable bit-flip
 917                  * occurred, or MTD reported about some data integrity error,
 918                  * like an ECC error in case of NAND. The former is harmless,
 919                  * the later may mean the read data is corrupted. But we have a
 920                  * CRC check-sum and we will identify this. If the VID header is
 921                  * still OK, we just report this as there was a bit-flip.
 922                  */
 923                 read_err = err;
 924         }
 925
 926         magic = be32_to_cpu(vid_hdr->magic);
 927         if (magic != UBI_VID_HDR_MAGIC) {
 928                 /*
 929                  * If we have read all 0xFF bytes, the VID header probably does
 930                  * not exist and the physical eraseblock is assumed to be free.
 931                  *
 932                  * But if there was a read error, we do not test the data for
 933                  * 0xFFs. Even if it does contain all 0xFFs, this error
 934                  * indicates that something is still wrong with this physical
 935                  * eraseblock and it cannot be regarded as free.
 936                  */
 937                 if (read_err != -EBADMSG &&
 938                     check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
 939                         /* The physical eraseblock is supposedly free */
 940
 941                         /*
 942                          * The below is just a paranoid check, it has to be
 943                          * compiled out if paranoid checks are disabled.
 944                          */
 945                         err = paranoid_check_all_ff(ubi, pnum, ubi->leb_start,
 946                                                     ubi->leb_size);
 947                         if (err)
 948                                 return err > 0 ? UBI_IO_BAD_VID_HDR : err;
 949
 950                         if (verbose)
 951                                 ubi_warn("no VID header found at PEB %d, "
 952                                          "only 0xFF bytes", pnum);
 953                         return UBI_IO_PEB_FREE;
 954                 }
 955
 956                 /*
 957                  * This is not a valid VID header, and these are not 0xFF
 958                  * bytes. Report that the header is corrupted.
 959                  */
 960                 if (verbose) {
 961                         ubi_warn("bad magic number at PEB %d: %08x instead of "
 962                                  "%08x", pnum, magic, UBI_VID_HDR_MAGIC);
 963                         ubi_dbg_dump_vid_hdr(vid_hdr);
 964                 }
 965                 return UBI_IO_BAD_VID_HDR;
 966         }
 967
 968         crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
 969         hdr_crc = be32_to_cpu(vid_hdr->hdr_crc);
 970
 971         if (hdr_crc != crc) {
 972                 if (verbose) {
 973                         ubi_warn("bad CRC at PEB %d, calculated %#08x, "
 974                                  "read %#08x", pnum, crc, hdr_crc);
 975                         ubi_dbg_dump_vid_hdr(vid_hdr);
 976                 }
 977                 return UBI_IO_BAD_VID_HDR;
 978         }
 979
 980         /* Validate the VID header that we have just read */
 981         err = validate_vid_hdr(ubi, vid_hdr);
 982         if (err) {
 983                 ubi_err("validation failed for PEB %d", pnum);
 984                 return -EINVAL;
 985         }
 986
 987         return read_err ? UBI_IO_BITFLIPS : 0;
 988 }
 989
 990 /**
 991  * ubi_io_write_vid_hdr - write a volume identifier header.
 992  * @ubi: UBI device description object
 993  * @pnum: the physical eraseblock number to write to
 994  * @vid_hdr: the volume identifier header to write
 995  *
 996  * This function writes the volume identifier header described by @vid_hdr to
 997  * physical eraseblock @pnum. This function automatically fills the
 998  * @vid_hdr->magic and the @vid_hdr->version fields, as well as calculates
 999  * header CRC checksum and stores it at vid_hdr->hdr_crc.
1000  *
1001  * This function returns zero in case of success and a negative error code in
1002  * case of failure. If %-EIO is returned, the physical eraseblock probably went
1003  * bad.
1004  */
1005 int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
1006                          struct ubi_vid_hdr *vid_hdr)
1007 {
1008         int err;
1009         uint32_t crc;
1010         void *p;
1011
1012         dbg_io("write VID header to PEB %d", pnum);
1013         ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
1014
1015         err = paranoid_check_peb_ec_hdr(ubi, pnum);
1016         if (err)
1017                 return err > 0 ? -EINVAL: err;
1018
1019         vid_hdr->magic = cpu_to_be32(UBI_VID_HDR_MAGIC);
1020         vid_hdr->version = UBI_VERSION;
1021         crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
1022         vid_hdr->hdr_crc = cpu_to_be32(crc);
1023
1024         err = paranoid_check_vid_hdr(ubi, pnum, vid_hdr);
1025         if (err)
1026                 return -EINVAL;
1027
1028         p = (char *)vid_hdr - ubi->vid_hdr_shift;
1029         err = ubi_io_write(ubi, p, pnum, ubi->vid_hdr_aloffset,
1030                            ubi->vid_hdr_alsize);
1031         return err;
1032 }
1033
1034 #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID
1035
1036 /**
1037  * paranoid_check_not_bad - ensure that a physical eraseblock is not bad.
1038  * @ubi: UBI device description object
1039  * @pnum: physical eraseblock number to check
1040  *
1041  * This function returns zero if the physical eraseblock is good, a positive
1042  * number if it is bad and a negative error code if an error occurred.
1043  */
1044 static int paranoid_check_not_bad(const struct ubi_device *ubi, int pnum)
1045 {
1046         int err;
1047
1048         err = ubi_io_is_bad(ubi, pnum);
1049         if (!err)
1050                 return err;
1051
1052         ubi_err("paranoid check failed for PEB %d", pnum);
1053         ubi_dbg_dump_stack();
1054         return err;
1055 }
1056
1057 /**
1058  * paranoid_check_ec_hdr - check if an erase counter header is all right.
1059  * @ubi: UBI device description object
1060  * @pnum: physical eraseblock number the erase counter header belongs to
1061  * @ec_hdr: the erase counter header to check
1062  *
1063  * This function returns zero if the erase counter header contains valid
1064  * values, and %1 if not.
1065  */
1066 static int paranoid_check_ec_hdr(const struct ubi_device *ubi, int pnum,
1067                                  const struct ubi_ec_hdr *ec_hdr)
1068 {
1069         int err;
1070         uint32_t magic;
1071
1072         magic = be32_to_cpu(ec_hdr->magic);
1073         if (magic != UBI_EC_HDR_MAGIC) {
1074                 ubi_err("bad magic %#08x, must be %#08x",
1075                         magic, UBI_EC_HDR_MAGIC);
1076                 goto fail;
1077         }
1078
1079         err = validate_ec_hdr(ubi, ec_hdr);
1080         if (err) {
1081                 ubi_err("paranoid check failed for PEB %d", pnum);
1082                 goto fail;
1083         }
1084
1085         return 0;
1086
1087 fail:
1088         ubi_dbg_dump_ec_hdr(ec_hdr);
1089         ubi_dbg_dump_stack();
1090         return 1;
1091 }
1092
1093 /**
1094  * paranoid_check_peb_ec_hdr - check that the erase counter header of a
1095  * physical eraseblock is in-place and is all right.
1096  * @ubi: UBI device description object
1097  * @pnum: the physical eraseblock number to check
1098  *
1099  * This function returns zero if the erase counter header is all right, %1 if
1100  * not, and a negative error code if an error occurred.
1101  */
1102 static int paranoid_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum)
1103 {
1104         int err;
1105         uint32_t crc, hdr_crc;
1106         struct ubi_ec_hdr *ec_hdr;
1107
1108         ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
1109         if (!ec_hdr)
1110                 return -ENOMEM;
1111
1112         err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
1113         if (err && err != UBI_IO_BITFLIPS && err != -EBADMSG)
1114                 goto exit;
1115
1116         crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
1117         hdr_crc = be32_to_cpu(ec_hdr->hdr_crc);
1118         if (hdr_crc != crc) {
1119                 ubi_err("bad CRC, calculated %#08x, read %#08x", crc, hdr_crc);
1120                 ubi_err("paranoid check failed for PEB %d", pnum);
1121                 ubi_dbg_dump_ec_hdr(ec_hdr);
1122                 ubi_dbg_dump_stack();
1123                 err = 1;
1124                 goto exit;
1125         }
1126
1127         err = paranoid_check_ec_hdr(ubi, pnum, ec_hdr);
1128
1129 exit:
1130         kfree(ec_hdr);
1131         return err;
1132 }
1133
1134 /**
1135  * paranoid_check_vid_hdr - check that a volume identifier header is all right.
1136  * @ubi: UBI device description object
1137  * @pnum: physical eraseblock number the volume identifier header belongs to
1138  * @vid_hdr: the volume identifier header to check
1139  *
1140  * This function returns zero if the volume identifier header is all right, and
1141  * %1 if not.
1142  */
1143 static int paranoid_check_vid_hdr(const struct ubi_device *ubi, int pnum,
1144                                   const struct ubi_vid_hdr *vid_hdr)
1145 {
1146         int err;
1147         uint32_t magic;
1148
1149         magic = be32_to_cpu(vid_hdr->magic);
1150         if (magic != UBI_VID_HDR_MAGIC) {
1151                 ubi_err("bad VID header magic %#08x at PEB %d, must be %#08x",
1152                         magic, pnum, UBI_VID_HDR_MAGIC);
1153                 goto fail;
1154         }
1155
1156         err = validate_vid_hdr(ubi, vid_hdr);
1157         if (err) {
1158                 ubi_err("paranoid check failed for PEB %d", pnum);
1159                 goto fail;
1160         }
1161
1162         return err;
1163
1164 fail:
1165         ubi_err("paranoid check failed for PEB %d", pnum);
1166         ubi_dbg_dump_vid_hdr(vid_hdr);
1167         ubi_dbg_dump_stack();
1168         return 1;
1169
1170 }
1171
1172 /**
1173  * paranoid_check_peb_vid_hdr - check that the volume identifier header of a
1174  * physical eraseblock is in-place and is all right.
1175  * @ubi: UBI device description object
1176  * @pnum: the physical eraseblock number to check
1177  *
1178  * This function returns zero if the volume identifier header is all right,
1179  * %1 if not, and a negative error code if an error occurred.
1180  */
1181 static int paranoid_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum)
1182 {
1183         int err;
1184         uint32_t crc, hdr_crc;
1185         struct ubi_vid_hdr *vid_hdr;
1186         void *p;
1187
1188         vid_hdr = ubi_zalloc_vid_hdr(ubi, GFP_NOFS);
1189         if (!vid_hdr)
1190                 return -ENOMEM;
1191
1192         p = (char *)vid_hdr - ubi->vid_hdr_shift;
1193         err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
1194                           ubi->vid_hdr_alsize);
1195         if (err && err != UBI_IO_BITFLIPS && err != -EBADMSG)
1196                 goto exit;
1197
1198         crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_EC_HDR_SIZE_CRC);
1199         hdr_crc = be32_to_cpu(vid_hdr->hdr_crc);
1200         if (hdr_crc != crc) {
1201                 ubi_err("bad VID header CRC at PEB %d, calculated %#08x, "
1202                         "read %#08x", pnum, crc, hdr_crc);
1203                 ubi_err("paranoid check failed for PEB %d", pnum);
1204                 ubi_dbg_dump_vid_hdr(vid_hdr);
1205                 ubi_dbg_dump_stack();
1206                 err = 1;
1207                 goto exit;
1208         }
1209
1210         err = paranoid_check_vid_hdr(ubi, pnum, vid_hdr);
1211
1212 exit:
1213         ubi_free_vid_hdr(ubi, vid_hdr);
1214         return err;
1215 }
1216
1217 /**
1218  * paranoid_check_all_ff - check that a region of flash is empty.
1219  * @ubi: UBI device description object
1220  * @pnum: the physical eraseblock number to check
1221  * @offset: the starting offset within the physical eraseblock to check
1222  * @len: the length of the region to check
1223  *
1224  * This function returns zero if only 0xFF bytes are present at offset
1225  * @offset of the physical eraseblock @pnum, %1 if not, and a negative error
1226  * code if an error occurred.
1227  */
1228 static int paranoid_check_all_ff(struct ubi_device *ubi, int pnum, int offset,
1229                                  int len)
1230 {
1231         size_t read;
1232         int err;
1233         loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
1234
1235         mutex_lock(&ubi->dbg_buf_mutex);
1236         err = ubi->mtd->read(ubi->mtd, addr, len, &read, ubi->dbg_peb_buf);
1237         if (err && err != -EUCLEAN) {
1238                 ubi_err("error %d while reading %d bytes from PEB %d:%d, "
1239                         "read %zd bytes", err, len, pnum, offset, read);
1240                 goto error;
1241         }
1242
1243         err = check_pattern(ubi->dbg_peb_buf, 0xFF, len);
1244         if (err == 0) {
1245                 ubi_err("flash region at PEB %d:%d, length %d does not "
1246                         "contain all 0xFF bytes", pnum, offset, len);
1247                 goto fail;
1248         }
1249         mutex_unlock(&ubi->dbg_buf_mutex);
1250
1251         return 0;
1252
1253 fail:
1254         ubi_err("paranoid check failed for PEB %d", pnum);
1255         dbg_msg("hex dump of the %d-%d region", offset, offset + len);
1256         print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
1257                        ubi->dbg_peb_buf, len, 1);
1258         err = 1;
1259 error:
1260         ubi_dbg_dump_stack();
1261         mutex_unlock(&ubi->dbg_buf_mutex);
1262         return err;
1263 }
1264
1265 #endif /* CONFIG_MTD_UBI_DEBUG_PARANOID */