drivers/mtd/mtdoops.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * MTD Oops/Panic logger
   4  *
   5  * Copyright © 2007 Nokia Corporation. All rights reserved.
   6  *
   7  * Author: Richard Purdie <rpurdie@openedhand.com>
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/console.h>
  15 #include <linux/vmalloc.h>
  16 #include <linux/workqueue.h>
  17 #include <linux/sched.h>
  18 #include <linux/wait.h>
  19 #include <linux/delay.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/timekeeping.h>
  22 #include <linux/mtd/mtd.h>
  23 #include <linux/kmsg_dump.h>
  24
  25 /* Maximum MTD partition size */
  26 #define MTDOOPS_MAX_MTD_SIZE (8 * 1024 * 1024)
  27
  28 static unsigned long record_size = 4096;
  29 module_param(record_size, ulong, 0400);
  30 MODULE_PARM_DESC(record_size,
  31                 "record size for MTD OOPS pages in bytes (default 4096)");
  32
  33 static char mtddev[80];
  34 module_param_string(mtddev, mtddev, 80, 0400);
  35 MODULE_PARM_DESC(mtddev,
  36                 "name or index number of the MTD device to use");
  37
  38 static int dump_oops = 1;
  39 module_param(dump_oops, int, 0600);
  40 MODULE_PARM_DESC(dump_oops,
  41                 "set to 1 to dump oopses, 0 to only dump panics (default 1)");
  42
  43 #define MTDOOPS_KERNMSG_MAGIC_v1 0x5d005d00  /* Original */
  44 #define MTDOOPS_KERNMSG_MAGIC_v2 0x5d005e00  /* Adds the timestamp */
  45
  46 struct mtdoops_hdr {
  47         u32 seq;
  48         u32 magic;
  49         ktime_t timestamp;
  50 } __packed;
  51
  52 static struct mtdoops_context {
  53         struct kmsg_dumper dump;
  54
  55         int mtd_index;
  56         struct work_struct work_erase;
  57         struct work_struct work_write;
  58         struct mtd_info *mtd;
  59         int oops_pages;
  60         int nextpage;
  61         int nextcount;
  62         unsigned long *oops_page_used;
  63
  64         unsigned long oops_buf_busy;
  65         void *oops_buf;
  66 } oops_cxt;
  67
  68 static void mark_page_used(struct mtdoops_context *cxt, int page)
  69 {
  70         set_bit(page, cxt->oops_page_used);
  71 }
  72
  73 static void mark_page_unused(struct mtdoops_context *cxt, int page)
  74 {
  75         clear_bit(page, cxt->oops_page_used);
  76 }
  77
  78 static int page_is_used(struct mtdoops_context *cxt, int page)
  79 {
  80         return test_bit(page, cxt->oops_page_used);
  81 }
  82
  83 static int mtdoops_erase_block(struct mtdoops_context *cxt, int offset)
  84 {
  85         struct mtd_info *mtd = cxt->mtd;
  86         u32 start_page_offset = mtd_div_by_eb(offset, mtd) * mtd->erasesize;
  87         u32 start_page = start_page_offset / record_size;
  88         u32 erase_pages = mtd->erasesize / record_size;
  89         struct erase_info erase;
  90         int ret;
  91         int page;
  92
  93         erase.addr = offset;
  94         erase.len = mtd->erasesize;
  95
  96         ret = mtd_erase(mtd, &erase);
  97         if (ret) {
  98                 pr_warn("erase of region [0x%llx, 0x%llx] on \"%s\" failed\n",
  99                         (unsigned long long)erase.addr,
 100                         (unsigned long long)erase.len, mtddev);
 101                 return ret;
 102         }
 103
 104         /* Mark pages as unused */
 105         for (page = start_page; page < start_page + erase_pages; page++)
 106                 mark_page_unused(cxt, page);
 107
 108         return 0;
 109 }
 110
 111 static void mtdoops_erase(struct mtdoops_context *cxt)
 112 {
 113         struct mtd_info *mtd = cxt->mtd;
 114         int i = 0, j, ret, mod;
 115
 116         /* We were unregistered */
 117         if (!mtd)
 118                 return;
 119
 120         mod = (cxt->nextpage * record_size) % mtd->erasesize;
 121         if (mod != 0) {
 122                 cxt->nextpage = cxt->nextpage + ((mtd->erasesize - mod) / record_size);
 123                 if (cxt->nextpage >= cxt->oops_pages)
 124                         cxt->nextpage = 0;
 125         }
 126
 127         while ((ret = mtd_block_isbad(mtd, cxt->nextpage * record_size)) > 0) {
 128 badblock:
 129                 pr_warn("bad block at %08lx\n",
 130                         cxt->nextpage * record_size);
 131                 i++;
 132                 cxt->nextpage = cxt->nextpage + (mtd->erasesize / record_size);
 133                 if (cxt->nextpage >= cxt->oops_pages)
 134                         cxt->nextpage = 0;
 135                 if (i == cxt->oops_pages / (mtd->erasesize / record_size)) {
 136                         pr_err("all blocks bad!\n");
 137                         return;
 138                 }
 139         }
 140
 141         if (ret < 0) {
 142                 pr_err("mtd_block_isbad failed, aborting\n");
 143                 return;
 144         }
 145
 146         for (j = 0, ret = -1; (j < 3) && (ret < 0); j++)
 147                 ret = mtdoops_erase_block(cxt, cxt->nextpage * record_size);
 148
 149         if (ret >= 0) {
 150                 pr_debug("ready %d, %d\n",
 151                          cxt->nextpage, cxt->nextcount);
 152                 return;
 153         }
 154
 155         if (ret == -EIO) {
 156                 ret = mtd_block_markbad(mtd, cxt->nextpage * record_size);
 157                 if (ret < 0 && ret != -EOPNOTSUPP) {
 158                         pr_err("block_markbad failed, aborting\n");
 159                         return;
 160                 }
 161         }
 162         goto badblock;
 163 }
 164
 165 /* Scheduled work - when we can't proceed without erasing a block */
 166 static void mtdoops_workfunc_erase(struct work_struct *work)
 167 {
 168         struct mtdoops_context *cxt =
 169                         container_of(work, struct mtdoops_context, work_erase);
 170         mtdoops_erase(cxt);
 171 }
 172
 173 static void mtdoops_inc_counter(struct mtdoops_context *cxt, int panic)
 174 {
 175         cxt->nextpage++;
 176         if (cxt->nextpage >= cxt->oops_pages)
 177                 cxt->nextpage = 0;
 178         cxt->nextcount++;
 179         if (cxt->nextcount == 0xffffffff)
 180                 cxt->nextcount = 0;
 181
 182         if (page_is_used(cxt, cxt->nextpage)) {
 183                 pr_debug("not ready %d, %d (erase %s)\n",
 184                          cxt->nextpage, cxt->nextcount,
 185                          panic ? "immediately" : "scheduled");
 186                 if (panic) {
 187                         /* In case of panic, erase immediately */
 188                         mtdoops_erase(cxt);
 189                 } else {
 190                         /* Otherwise, schedule work to erase it "nicely" */
 191                         schedule_work(&cxt->work_erase);
 192                 }
 193         } else {
 194                 pr_debug("ready %d, %d (no erase)\n",
 195                          cxt->nextpage, cxt->nextcount);
 196         }
 197 }
 198
 199 static void mtdoops_write(struct mtdoops_context *cxt, int panic)
 200 {
 201         struct mtd_info *mtd = cxt->mtd;
 202         size_t retlen;
 203         struct mtdoops_hdr *hdr;
 204         int ret;
 205
 206         if (test_and_set_bit(0, &cxt->oops_buf_busy))
 207                 return;
 208
 209         /* Add mtdoops header to the buffer */
 210         hdr = (struct mtdoops_hdr *)cxt->oops_buf;
 211         hdr->seq = cxt->nextcount;
 212         hdr->magic = MTDOOPS_KERNMSG_MAGIC_v2;
 213         hdr->timestamp = ktime_get_real();
 214
 215         if (panic) {
 216                 ret = mtd_panic_write(mtd, cxt->nextpage * record_size,
 217                                       record_size, &retlen, cxt->oops_buf);
 218                 if (ret == -EOPNOTSUPP) {
 219                         pr_err("Cannot write from panic without panic_write\n");
 220                         goto out;
 221                 }
 222         } else
 223                 ret = mtd_write(mtd, cxt->nextpage * record_size,
 224                                 record_size, &retlen, cxt->oops_buf);
 225
 226         if (retlen != record_size || ret < 0)
 227                 pr_err("write failure at %ld (%td of %ld written), error %d\n",
 228                        cxt->nextpage * record_size, retlen, record_size, ret);
 229         mark_page_used(cxt, cxt->nextpage);
 230         memset(cxt->oops_buf, 0xff, record_size);
 231
 232         mtdoops_inc_counter(cxt, panic);
 233 out:
 234         clear_bit(0, &cxt->oops_buf_busy);
 235 }
 236
 237 static void mtdoops_workfunc_write(struct work_struct *work)
 238 {
 239         struct mtdoops_context *cxt =
 240                         container_of(work, struct mtdoops_context, work_write);
 241
 242         mtdoops_write(cxt, 0);
 243 }
 244
 245 static void find_next_position(struct mtdoops_context *cxt)
 246 {
 247         struct mtd_info *mtd = cxt->mtd;
 248         struct mtdoops_hdr hdr;
 249         int ret, page, maxpos = 0;
 250         u32 maxcount = 0xffffffff;
 251         size_t retlen;
 252
 253         for (page = 0; page < cxt->oops_pages; page++) {
 254                 if (mtd_block_isbad(mtd, page * record_size))
 255                         continue;
 256                 /* Assume the page is used */
 257                 mark_page_used(cxt, page);
 258                 ret = mtd_read(mtd, page * record_size, sizeof(hdr),
 259                                &retlen, (u_char *)&hdr);
 260                 if (retlen != sizeof(hdr) ||
 261                                 (ret < 0 && !mtd_is_bitflip(ret))) {
 262                         pr_err("read failure at %ld (%zu of %zu read), err %d\n",
 263                                page * record_size, retlen, sizeof(hdr), ret);
 264                         continue;
 265                 }
 266
 267                 if (hdr.seq == 0xffffffff && hdr.magic == 0xffffffff)
 268                         mark_page_unused(cxt, page);
 269                 if (hdr.seq == 0xffffffff ||
 270                     (hdr.magic != MTDOOPS_KERNMSG_MAGIC_v1 &&
 271                      hdr.magic != MTDOOPS_KERNMSG_MAGIC_v2))
 272                         continue;
 273                 if (maxcount == 0xffffffff) {
 274                         maxcount = hdr.seq;
 275                         maxpos = page;
 276                 } else if (hdr.seq < 0x40000000 && maxcount > 0xc0000000) {
 277                         maxcount = hdr.seq;
 278                         maxpos = page;
 279                 } else if (hdr.seq > maxcount && hdr.seq < 0xc0000000) {
 280                         maxcount = hdr.seq;
 281                         maxpos = page;
 282                 } else if (hdr.seq > maxcount && hdr.seq > 0xc0000000
 283                                         && maxcount > 0x80000000) {
 284                         maxcount = hdr.seq;
 285                         maxpos = page;
 286                 }
 287         }
 288         if (maxcount == 0xffffffff) {
 289                 cxt->nextpage = cxt->oops_pages - 1;
 290                 cxt->nextcount = 0;
 291         }
 292         else {
 293                 cxt->nextpage = maxpos;
 294                 cxt->nextcount = maxcount;
 295         }
 296
 297         mtdoops_inc_counter(cxt, 0);
 298 }
 299
 300 static void mtdoops_do_dump(struct kmsg_dumper *dumper,
 301                             struct kmsg_dump_detail *detail)
 302 {
 303         struct mtdoops_context *cxt = container_of(dumper,
 304                         struct mtdoops_context, dump);
 305         struct kmsg_dump_iter iter;
 306
 307         /* Only dump oopses if dump_oops is set */
 308         if (detail->reason == KMSG_DUMP_OOPS && !dump_oops)
 309                 return;
 310
 311         kmsg_dump_rewind(&iter);
 312
 313         if (test_and_set_bit(0, &cxt->oops_buf_busy))
 314                 return;
 315         kmsg_dump_get_buffer(&iter, true,
 316                              cxt->oops_buf + sizeof(struct mtdoops_hdr),
 317                              record_size - sizeof(struct mtdoops_hdr), NULL);
 318         clear_bit(0, &cxt->oops_buf_busy);
 319
 320         if (detail->reason != KMSG_DUMP_OOPS) {
 321                 /* Panics must be written immediately */
 322                 mtdoops_write(cxt, 1);
 323         } else {
 324                 /* For other cases, schedule work to write it "nicely" */
 325                 schedule_work(&cxt->work_write);
 326         }
 327 }
 328
 329 static void mtdoops_notify_add(struct mtd_info *mtd)
 330 {
 331         struct mtdoops_context *cxt = &oops_cxt;
 332         u64 mtdoops_pages = div_u64(mtd->size, record_size);
 333         int err;
 334
 335         if (!strcmp(mtd->name, mtddev))
 336                 cxt->mtd_index = mtd->index;
 337
 338         if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
 339                 return;
 340
 341         if (mtd->size < mtd->erasesize * 2) {
 342                 pr_err("MTD partition %d not big enough for mtdoops\n",
 343                        mtd->index);
 344                 return;
 345         }
 346         if (mtd->erasesize < record_size) {
 347                 pr_err("eraseblock size of MTD partition %d too small\n",
 348                        mtd->index);
 349                 return;
 350         }
 351         if (mtd->size > MTDOOPS_MAX_MTD_SIZE) {
 352                 pr_err("mtd%d is too large (limit is %d MiB)\n",
 353                        mtd->index, MTDOOPS_MAX_MTD_SIZE / 1024 / 1024);
 354                 return;
 355         }
 356
 357         /* oops_page_used is a bit field */
 358         cxt->oops_page_used =
 359                 vmalloc(array_size(sizeof(unsigned long),
 360                                    DIV_ROUND_UP(mtdoops_pages,
 361                                                 BITS_PER_LONG)));
 362         if (!cxt->oops_page_used) {
 363                 pr_err("could not allocate page array\n");
 364                 return;
 365         }
 366
 367         cxt->dump.max_reason = KMSG_DUMP_OOPS;
 368         cxt->dump.dump = mtdoops_do_dump;
 369         err = kmsg_dump_register(&cxt->dump);
 370         if (err) {
 371                 pr_err("registering kmsg dumper failed, error %d\n", err);
 372                 vfree(cxt->oops_page_used);
 373                 cxt->oops_page_used = NULL;
 374                 return;
 375         }
 376
 377         cxt->mtd = mtd;
 378         cxt->oops_pages = (int)mtd->size / record_size;
 379         find_next_position(cxt);
 380         pr_info("Attached to MTD device %d\n", mtd->index);
 381 }
 382
 383 static void mtdoops_notify_remove(struct mtd_info *mtd)
 384 {
 385         struct mtdoops_context *cxt = &oops_cxt;
 386
 387         if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
 388                 return;
 389
 390         if (kmsg_dump_unregister(&cxt->dump) < 0)
 391                 pr_warn("could not unregister kmsg_dumper\n");
 392
 393         cxt->mtd = NULL;
 394         flush_work(&cxt->work_erase);
 395         flush_work(&cxt->work_write);
 396 }
 397
 398
 399 static struct mtd_notifier mtdoops_notifier = {
 400         .add    = mtdoops_notify_add,
 401         .remove = mtdoops_notify_remove,
 402 };
 403
 404 static int __init mtdoops_init(void)
 405 {
 406         struct mtdoops_context *cxt = &oops_cxt;
 407         int mtd_index;
 408         char *endp;
 409
 410         if (strlen(mtddev) == 0) {
 411                 pr_err("mtd device (mtddev=name/number) must be supplied\n");
 412                 return -EINVAL;
 413         }
 414         if ((record_size & 4095) != 0) {
 415                 pr_err("record_size must be a multiple of 4096\n");
 416                 return -EINVAL;
 417         }
 418         if (record_size < 4096) {
 419                 pr_err("record_size must be over 4096 bytes\n");
 420                 return -EINVAL;
 421         }
 422
 423         /* Setup the MTD device to use */
 424         cxt->mtd_index = -1;
 425         mtd_index = simple_strtoul(mtddev, &endp, 0);
 426         if (*endp == '\0')
 427                 cxt->mtd_index = mtd_index;
 428
 429         cxt->oops_buf = vmalloc(record_size);
 430         if (!cxt->oops_buf)
 431                 return -ENOMEM;
 432         memset(cxt->oops_buf, 0xff, record_size);
 433         cxt->oops_buf_busy = 0;
 434
 435         INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
 436         INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);
 437
 438         register_mtd_user(&mtdoops_notifier);
 439         return 0;
 440 }
 441
 442 static void __exit mtdoops_exit(void)
 443 {
 444         struct mtdoops_context *cxt = &oops_cxt;
 445
 446         unregister_mtd_user(&mtdoops_notifier);
 447         vfree(cxt->oops_buf);
 448         vfree(cxt->oops_page_used);
 449 }
 450
 451
 452 module_init(mtdoops_init);
 453 module_exit(mtdoops_exit);
 454
 455 MODULE_LICENSE("GPL");
 456 MODULE_AUTHOR("Richard Purdie <rpurdie@openedhand.com>");
 457 MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");