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