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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#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
28static unsigned long record_size = 4096;
29module_param(record_size, ulong, 0400);
30MODULE_PARM_DESC(record_size,
31 "record size for MTD OOPS pages in bytes (default 4096)");
32
33static char mtddev[80];
34module_param_string(mtddev, mtddev, 80, 0400);
35MODULE_PARM_DESC(mtddev,
36 "name or index number of the MTD device to use");
37
38static int dump_oops = 1;
39module_param(dump_oops, int, 0600);
40MODULE_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
46struct mtdoops_hdr {
47 u32 seq;
48 u32 magic;
49 ktime_t timestamp;
50} __packed;
51
52static 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
68static void mark_page_used(struct mtdoops_context *cxt, int page)
69{
70 set_bit(page, cxt->oops_page_used);
71}
72
73static void mark_page_unused(struct mtdoops_context *cxt, int page)
74{
75 clear_bit(page, cxt->oops_page_used);
76}
77
78static int page_is_used(struct mtdoops_context *cxt, int page)
79{
80 return test_bit(page, cxt->oops_page_used);
81}
82
83static 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
111static 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) {
128badblock:
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 */
166static 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
173static 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
199static 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);
233out:
234 clear_bit(0, &cxt->oops_buf_busy);
235}
236
237static 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
245static 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
300static 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
329static 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(DIV_ROUND_UP(mtdoops_pages, BITS_PER_LONG),
360 sizeof(unsigned long));
361 if (!cxt->oops_page_used) {
362 pr_err("could not allocate page array\n");
363 return;
364 }
365
366 cxt->dump.max_reason = KMSG_DUMP_OOPS;
367 cxt->dump.dump = mtdoops_do_dump;
368 err = kmsg_dump_register(&cxt->dump);
369 if (err) {
370 pr_err("registering kmsg dumper failed, error %d\n", err);
371 vfree(cxt->oops_page_used);
372 cxt->oops_page_used = NULL;
373 return;
374 }
375
376 cxt->mtd = mtd;
377 cxt->oops_pages = (int)mtd->size / record_size;
378 find_next_position(cxt);
379 pr_info("Attached to MTD device %d\n", mtd->index);
380}
381
382static void mtdoops_notify_remove(struct mtd_info *mtd)
383{
384 struct mtdoops_context *cxt = &oops_cxt;
385
386 if (mtd->index != cxt->mtd_index || cxt->mtd_index < 0)
387 return;
388
389 if (kmsg_dump_unregister(&cxt->dump) < 0)
390 pr_warn("could not unregister kmsg_dumper\n");
391
392 cxt->mtd = NULL;
393 flush_work(&cxt->work_erase);
394 flush_work(&cxt->work_write);
395 vfree(cxt->oops_page_used);
396 cxt->oops_page_used = NULL;
397 cxt->oops_pages = 0;
398}
399
400
401static struct mtd_notifier mtdoops_notifier = {
402 .add = mtdoops_notify_add,
403 .remove = mtdoops_notify_remove,
404};
405
406static int __init mtdoops_init(void)
407{
408 struct mtdoops_context *cxt = &oops_cxt;
409 unsigned int mtd_index;
410
411 if (strlen(mtddev) == 0) {
412 pr_err("mtd device (mtddev=name/number) must be supplied\n");
413 return -EINVAL;
414 }
415 if ((record_size & 4095) != 0) {
416 pr_err("record_size must be a multiple of 4096\n");
417 return -EINVAL;
418 }
419 if (record_size < 4096) {
420 pr_err("record_size must be over 4096 bytes\n");
421 return -EINVAL;
422 }
423
424 /* Setup the MTD device to use */
425 cxt->mtd_index = -1;
426 if (kstrtouint(mtddev, 0, &mtd_index) == 0) {
427 cxt->mtd_index = mtd_index;
428 }
429
430 cxt->oops_buf = vmalloc(record_size);
431 if (!cxt->oops_buf)
432 return -ENOMEM;
433 memset(cxt->oops_buf, 0xff, record_size);
434 cxt->oops_buf_busy = 0;
435
436 INIT_WORK(&cxt->work_erase, mtdoops_workfunc_erase);
437 INIT_WORK(&cxt->work_write, mtdoops_workfunc_write);
438
439 register_mtd_user(&mtdoops_notifier);
440 return 0;
441}
442
443static void __exit mtdoops_exit(void)
444{
445 struct mtdoops_context *cxt = &oops_cxt;
446
447 unregister_mtd_user(&mtdoops_notifier);
448 vfree(cxt->oops_buf);
449 vfree(cxt->oops_page_used);
450}
451
452
453module_init(mtdoops_init);
454module_exit(mtdoops_exit);
455
456MODULE_LICENSE("GPL");
457MODULE_AUTHOR("Richard Purdie <[email protected]>");
458MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");