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