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