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(nr: page, addr: cxt->oops_page_used); |
71 | } |
72 | |
73 | static void mark_page_unused(struct mtdoops_context *cxt, int page) |
74 | { |
75 | clear_bit(nr: page, addr: 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(sz: 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, instr: &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, ofs: 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, offset: 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, ofs: 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, page: 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(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(nr: 0, addr: &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, to: cxt->nextpage * record_size, |
217 | len: record_size, retlen: &retlen, buf: 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, to: cxt->nextpage * record_size, |
224 | len: record_size, retlen: &retlen, buf: 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, page: cxt->nextpage); |
230 | memset(cxt->oops_buf, 0xff, record_size); |
231 | |
232 | mtdoops_inc_counter(cxt, panic); |
233 | out: |
234 | clear_bit(nr: 0, addr: &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, panic: 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, ofs: page * record_size)) |
255 | continue; |
256 | /* Assume the page is used */ |
257 | mark_page_used(cxt, page); |
258 | ret = mtd_read(mtd, from: page * record_size, len: sizeof(hdr), |
259 | retlen: &retlen, buf: (u_char *)&hdr); |
260 | if (retlen != sizeof(hdr) || |
261 | (ret < 0 && !mtd_is_bitflip(err: 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, panic: 0); |
298 | } |
299 | |
300 | static void mtdoops_do_dump(struct kmsg_dumper *dumper, |
301 | enum kmsg_dump_reason reason) |
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 (reason == KMSG_DUMP_OOPS && !dump_oops) |
309 | return; |
310 | |
311 | kmsg_dump_rewind(iter: &iter); |
312 | |
313 | if (test_and_set_bit(nr: 0, addr: &cxt->oops_buf_busy)) |
314 | return; |
315 | kmsg_dump_get_buffer(iter: &iter, syslog: true, |
316 | buf: cxt->oops_buf + sizeof(struct mtdoops_hdr), |
317 | size: record_size - sizeof(struct mtdoops_hdr), NULL); |
318 | clear_bit(nr: 0, addr: &cxt->oops_buf_busy); |
319 | |
320 | if (reason != KMSG_DUMP_OOPS) { |
321 | /* Panics must be written immediately */ |
322 | mtdoops_write(cxt, panic: 1); |
323 | } else { |
324 | /* For other cases, schedule work to write it "nicely" */ |
325 | schedule_work(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(dividend: mtd->size, divisor: 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(dumper: &cxt->dump); |
370 | if (err) { |
371 | pr_err("registering kmsg dumper failed, error %d\n" , err); |
372 | vfree(addr: 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(dumper: &cxt->dump) < 0) |
391 | pr_warn("could not unregister kmsg_dumper\n" ); |
392 | |
393 | cxt->mtd = NULL; |
394 | flush_work(work: &cxt->work_erase); |
395 | flush_work(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(size: 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(new: &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(old: &mtdoops_notifier); |
447 | vfree(addr: cxt->oops_buf); |
448 | vfree(addr: 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" ); |
458 | |