1 /*
2 * Persistent Storage - platform driver interface parts.
3 *
4 * Copyright (C) 2007-2008 Google, Inc.
5 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19 */
20
21 #define pr_fmt(fmt) "pstore: " fmt
22
23 #include <linux/atomic.h>
24 #include <linux/types.h>
25 #include <linux/errno.h>
26 #include <linux/init.h>
27 #include <linux/kmsg_dump.h>
28 #include <linux/console.h>
29 #include <linux/module.h>
30 #include <linux/pstore.h>
31 #include <linux/zlib.h>
32 #include <linux/string.h>
33 #include <linux/timer.h>
34 #include <linux/slab.h>
35 #include <linux/uaccess.h>
36 #include <linux/hardirq.h>
37 #include <linux/jiffies.h>
38 #include <linux/workqueue.h>
39
40 #include "internal.h"
41
42 /*
43 * We defer making "oops" entries appear in pstore - see
44 * whether the system is actually still running well enough
45 * to let someone see the entry
46 */
47 static int pstore_update_ms = -1;
48 module_param_named(update_ms, pstore_update_ms, int, 0600);
49 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
50 "(default is -1, which means runtime updates are disabled; "
51 "enabling this option is not safe, it may lead to further "
52 "corruption on Oopses)");
53
54 static int pstore_new_entry;
55
56 static void pstore_timefunc(unsigned long);
57 static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
58
59 static void pstore_dowork(struct work_struct *);
60 static DECLARE_WORK(pstore_work, pstore_dowork);
61
62 /*
63 * pstore_lock just protects "psinfo" during
64 * calls to pstore_register()
65 */
66 static DEFINE_SPINLOCK(pstore_lock);
67 struct pstore_info *psinfo;
68
69 static char *backend;
70
71 /* Compression parameters */
72 #define COMPR_LEVEL 6
73 #define WINDOW_BITS 12
74 #define MEM_LEVEL 4
75 static struct z_stream_s stream;
76
77 static char *big_oops_buf;
78 static size_t big_oops_buf_sz;
79
80 /* How much of the console log to snapshot */
81 static unsigned long kmsg_bytes = 10240;
82
pstore_set_kmsg_bytes(int bytes)83 void pstore_set_kmsg_bytes(int bytes)
84 {
85 kmsg_bytes = bytes;
86 }
87
88 /* Tag each group of saved records with a sequence number */
89 static int oopscount;
90
get_reason_str(enum kmsg_dump_reason reason)91 static const char *get_reason_str(enum kmsg_dump_reason reason)
92 {
93 switch (reason) {
94 case KMSG_DUMP_PANIC:
95 return "Panic";
96 case KMSG_DUMP_OOPS:
97 return "Oops";
98 case KMSG_DUMP_EMERG:
99 return "Emergency";
100 case KMSG_DUMP_RESTART:
101 return "Restart";
102 case KMSG_DUMP_HALT:
103 return "Halt";
104 case KMSG_DUMP_POWEROFF:
105 return "Poweroff";
106 default:
107 return "Unknown";
108 }
109 }
110
pstore_cannot_block_path(enum kmsg_dump_reason reason)111 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
112 {
113 /*
114 * In case of NMI path, pstore shouldn't be blocked
115 * regardless of reason.
116 */
117 if (in_nmi())
118 return true;
119
120 switch (reason) {
121 /* In panic case, other cpus are stopped by smp_send_stop(). */
122 case KMSG_DUMP_PANIC:
123 /* Emergency restart shouldn't be blocked by spin lock. */
124 case KMSG_DUMP_EMERG:
125 return true;
126 default:
127 return false;
128 }
129 }
130 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
131
132 /* Derived from logfs_compress() */
pstore_compress(const void * in,void * out,size_t inlen,size_t outlen)133 static int pstore_compress(const void *in, void *out, size_t inlen,
134 size_t outlen)
135 {
136 int err, ret;
137
138 ret = -EIO;
139 err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
140 MEM_LEVEL, Z_DEFAULT_STRATEGY);
141 if (err != Z_OK)
142 goto error;
143
144 stream.next_in = in;
145 stream.avail_in = inlen;
146 stream.total_in = 0;
147 stream.next_out = out;
148 stream.avail_out = outlen;
149 stream.total_out = 0;
150
151 err = zlib_deflate(&stream, Z_FINISH);
152 if (err != Z_STREAM_END)
153 goto error;
154
155 err = zlib_deflateEnd(&stream);
156 if (err != Z_OK)
157 goto error;
158
159 if (stream.total_out >= stream.total_in)
160 goto error;
161
162 ret = stream.total_out;
163 error:
164 return ret;
165 }
166
167 /* Derived from logfs_uncompress */
pstore_decompress(void * in,void * out,size_t inlen,size_t outlen)168 static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
169 {
170 int err, ret;
171
172 ret = -EIO;
173 err = zlib_inflateInit2(&stream, WINDOW_BITS);
174 if (err != Z_OK)
175 goto error;
176
177 stream.next_in = in;
178 stream.avail_in = inlen;
179 stream.total_in = 0;
180 stream.next_out = out;
181 stream.avail_out = outlen;
182 stream.total_out = 0;
183
184 err = zlib_inflate(&stream, Z_FINISH);
185 if (err != Z_STREAM_END)
186 goto error;
187
188 err = zlib_inflateEnd(&stream);
189 if (err != Z_OK)
190 goto error;
191
192 ret = stream.total_out;
193 error:
194 return ret;
195 }
196
allocate_buf_for_compression(void)197 static void allocate_buf_for_compression(void)
198 {
199 size_t size;
200 size_t cmpr;
201
202 switch (psinfo->bufsize) {
203 /* buffer range for efivars */
204 case 1000 ... 2000:
205 cmpr = 56;
206 break;
207 case 2001 ... 3000:
208 cmpr = 54;
209 break;
210 case 3001 ... 3999:
211 cmpr = 52;
212 break;
213 /* buffer range for nvram, erst */
214 case 4000 ... 10000:
215 cmpr = 45;
216 break;
217 default:
218 cmpr = 60;
219 break;
220 }
221
222 big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
223 big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
224 if (big_oops_buf) {
225 size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
226 zlib_inflate_workspacesize());
227 stream.workspace = kmalloc(size, GFP_KERNEL);
228 if (!stream.workspace) {
229 pr_err("No memory for compression workspace; skipping compression\n");
230 kfree(big_oops_buf);
231 big_oops_buf = NULL;
232 }
233 } else {
234 pr_err("No memory for uncompressed data; skipping compression\n");
235 stream.workspace = NULL;
236 }
237
238 }
239
free_buf_for_compression(void)240 static void free_buf_for_compression(void)
241 {
242 kfree(stream.workspace);
243 stream.workspace = NULL;
244 kfree(big_oops_buf);
245 big_oops_buf = NULL;
246 }
247
248 /*
249 * Called when compression fails, since the printk buffer
250 * would be fetched for compression calling it again when
251 * compression fails would have moved the iterator of
252 * printk buffer which results in fetching old contents.
253 * Copy the recent messages from big_oops_buf to psinfo->buf
254 */
copy_kmsg_to_buffer(int hsize,size_t len)255 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
256 {
257 size_t total_len;
258 size_t diff;
259
260 total_len = hsize + len;
261
262 if (total_len > psinfo->bufsize) {
263 diff = total_len - psinfo->bufsize + hsize;
264 memcpy(psinfo->buf, big_oops_buf, hsize);
265 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
266 psinfo->bufsize - hsize);
267 total_len = psinfo->bufsize;
268 } else
269 memcpy(psinfo->buf, big_oops_buf, total_len);
270
271 return total_len;
272 }
273
274 /*
275 * callback from kmsg_dump. (s2,l2) has the most recently
276 * written bytes, older bytes are in (s1,l1). Save as much
277 * as we can from the end of the buffer.
278 */
pstore_dump(struct kmsg_dumper * dumper,enum kmsg_dump_reason reason)279 static void pstore_dump(struct kmsg_dumper *dumper,
280 enum kmsg_dump_reason reason)
281 {
282 unsigned long total = 0;
283 const char *why;
284 u64 id;
285 unsigned int part = 1;
286 unsigned long flags = 0;
287 int is_locked = 0;
288 int ret;
289
290 why = get_reason_str(reason);
291
292 if (pstore_cannot_block_path(reason)) {
293 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
294 if (!is_locked) {
295 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
296 , in_nmi() ? "NMI" : why);
297 }
298 } else
299 spin_lock_irqsave(&psinfo->buf_lock, flags);
300 oopscount++;
301 while (total < kmsg_bytes) {
302 char *dst;
303 unsigned long size;
304 int hsize;
305 int zipped_len = -1;
306 size_t len;
307 bool compressed;
308 size_t total_len;
309
310 if (big_oops_buf && is_locked) {
311 dst = big_oops_buf;
312 hsize = sprintf(dst, "%s#%d Part%u\n", why,
313 oopscount, part);
314 size = big_oops_buf_sz - hsize;
315
316 if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
317 size, &len))
318 break;
319
320 zipped_len = pstore_compress(dst, psinfo->buf,
321 hsize + len, psinfo->bufsize);
322
323 if (zipped_len > 0) {
324 compressed = true;
325 total_len = zipped_len;
326 } else {
327 compressed = false;
328 total_len = copy_kmsg_to_buffer(hsize, len);
329 }
330 } else {
331 dst = psinfo->buf;
332 hsize = sprintf(dst, "%s#%d Part%u\n", why, oopscount,
333 part);
334 size = psinfo->bufsize - hsize;
335 dst += hsize;
336
337 if (!kmsg_dump_get_buffer(dumper, true, dst,
338 size, &len))
339 break;
340
341 compressed = false;
342 total_len = hsize + len;
343 }
344
345 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
346 oopscount, compressed, total_len, psinfo);
347 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
348 pstore_new_entry = 1;
349
350 total += total_len;
351 part++;
352 }
353 if (pstore_cannot_block_path(reason)) {
354 if (is_locked)
355 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
356 } else
357 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
358 }
359
360 static struct kmsg_dumper pstore_dumper = {
361 .dump = pstore_dump,
362 };
363
364 /*
365 * Register with kmsg_dump to save last part of console log on panic.
366 */
pstore_register_kmsg(void)367 static void pstore_register_kmsg(void)
368 {
369 kmsg_dump_register(&pstore_dumper);
370 }
371
pstore_unregister_kmsg(void)372 static void pstore_unregister_kmsg(void)
373 {
374 kmsg_dump_unregister(&pstore_dumper);
375 }
376
377 #ifdef CONFIG_PSTORE_CONSOLE
pstore_console_write(struct console * con,const char * s,unsigned c)378 static void pstore_console_write(struct console *con, const char *s, unsigned c)
379 {
380 const char *e = s + c;
381
382 while (s < e) {
383 unsigned long flags;
384 u64 id;
385
386 if (c > psinfo->bufsize)
387 c = psinfo->bufsize;
388
389 if (oops_in_progress) {
390 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
391 break;
392 } else {
393 spin_lock_irqsave(&psinfo->buf_lock, flags);
394 }
395 psinfo->write_buf(PSTORE_TYPE_CONSOLE, 0, &id, 0,
396 s, 0, c, psinfo);
397 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
398 s += c;
399 c = e - s;
400 }
401 }
402
403 static struct console pstore_console = {
404 .name = "pstore",
405 .write = pstore_console_write,
406 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
407 .index = -1,
408 };
409
pstore_register_console(void)410 static void pstore_register_console(void)
411 {
412 register_console(&pstore_console);
413 }
414
pstore_unregister_console(void)415 static void pstore_unregister_console(void)
416 {
417 unregister_console(&pstore_console);
418 }
419 #else
pstore_register_console(void)420 static void pstore_register_console(void) {}
pstore_unregister_console(void)421 static void pstore_unregister_console(void) {}
422 #endif
423
pstore_write_compat(enum pstore_type_id type,enum kmsg_dump_reason reason,u64 * id,unsigned int part,int count,bool compressed,size_t size,struct pstore_info * psi)424 static int pstore_write_compat(enum pstore_type_id type,
425 enum kmsg_dump_reason reason,
426 u64 *id, unsigned int part, int count,
427 bool compressed, size_t size,
428 struct pstore_info *psi)
429 {
430 return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
431 size, psi);
432 }
433
pstore_write_buf_user_compat(enum pstore_type_id type,enum kmsg_dump_reason reason,u64 * id,unsigned int part,const char __user * buf,bool compressed,size_t size,struct pstore_info * psi)434 static int pstore_write_buf_user_compat(enum pstore_type_id type,
435 enum kmsg_dump_reason reason,
436 u64 *id, unsigned int part,
437 const char __user *buf,
438 bool compressed, size_t size,
439 struct pstore_info *psi)
440 {
441 unsigned long flags = 0;
442 size_t i, bufsize = size;
443 long ret = 0;
444
445 if (unlikely(!access_ok(VERIFY_READ, buf, size)))
446 return -EFAULT;
447 if (bufsize > psinfo->bufsize)
448 bufsize = psinfo->bufsize;
449 spin_lock_irqsave(&psinfo->buf_lock, flags);
450 for (i = 0; i < size; ) {
451 size_t c = min(size - i, bufsize);
452
453 ret = __copy_from_user(psinfo->buf, buf + i, c);
454 if (unlikely(ret != 0)) {
455 ret = -EFAULT;
456 break;
457 }
458 ret = psi->write_buf(type, reason, id, part, psinfo->buf,
459 compressed, c, psi);
460 if (unlikely(ret < 0))
461 break;
462 i += c;
463 }
464 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
465 return unlikely(ret < 0) ? ret : size;
466 }
467
468 /*
469 * platform specific persistent storage driver registers with
470 * us here. If pstore is already mounted, call the platform
471 * read function right away to populate the file system. If not
472 * then the pstore mount code will call us later to fill out
473 * the file system.
474 */
pstore_register(struct pstore_info * psi)475 int pstore_register(struct pstore_info *psi)
476 {
477 struct module *owner = psi->owner;
478
479 if (backend && strcmp(backend, psi->name))
480 return -EPERM;
481
482 spin_lock(&pstore_lock);
483 if (psinfo) {
484 spin_unlock(&pstore_lock);
485 return -EBUSY;
486 }
487
488 if (!psi->write)
489 psi->write = pstore_write_compat;
490 if (!psi->write_buf_user)
491 psi->write_buf_user = pstore_write_buf_user_compat;
492 psinfo = psi;
493 mutex_init(&psinfo->read_mutex);
494 spin_unlock(&pstore_lock);
495
496 if (owner && !try_module_get(owner)) {
497 psinfo = NULL;
498 return -EINVAL;
499 }
500
501 allocate_buf_for_compression();
502
503 if (pstore_is_mounted())
504 pstore_get_records(0);
505
506 pstore_register_kmsg();
507
508 if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
509 pstore_register_console();
510 pstore_register_ftrace();
511 pstore_register_pmsg();
512 }
513
514 if (pstore_update_ms >= 0) {
515 pstore_timer.expires = jiffies +
516 msecs_to_jiffies(pstore_update_ms);
517 add_timer(&pstore_timer);
518 }
519
520 /*
521 * Update the module parameter backend, so it is visible
522 * through /sys/module/pstore/parameters/backend
523 */
524 backend = psi->name;
525
526 module_put(owner);
527
528 pr_info("Registered %s as persistent store backend\n", psi->name);
529
530 return 0;
531 }
532 EXPORT_SYMBOL_GPL(pstore_register);
533
pstore_unregister(struct pstore_info * psi)534 void pstore_unregister(struct pstore_info *psi)
535 {
536 pstore_unregister_pmsg();
537 pstore_unregister_ftrace();
538 pstore_unregister_console();
539 pstore_unregister_kmsg();
540
541 free_buf_for_compression();
542
543 psinfo = NULL;
544 backend = NULL;
545 }
546 EXPORT_SYMBOL_GPL(pstore_unregister);
547
548 /*
549 * Read all the records from the persistent store. Create
550 * files in our filesystem. Don't warn about -EEXIST errors
551 * when we are re-scanning the backing store looking to add new
552 * error records.
553 */
pstore_get_records(int quiet)554 void pstore_get_records(int quiet)
555 {
556 struct pstore_info *psi = psinfo;
557 char *buf = NULL;
558 ssize_t size;
559 u64 id;
560 int count;
561 enum pstore_type_id type;
562 struct timespec time;
563 int failed = 0, rc;
564 bool compressed;
565 int unzipped_len = -1;
566
567 if (!psi)
568 return;
569
570 mutex_lock(&psi->read_mutex);
571 if (psi->open && psi->open(psi))
572 goto out;
573
574 while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
575 psi)) > 0) {
576 if (compressed && (type == PSTORE_TYPE_DMESG)) {
577 if (big_oops_buf)
578 unzipped_len = pstore_decompress(buf,
579 big_oops_buf, size,
580 big_oops_buf_sz);
581
582 if (unzipped_len > 0) {
583 kfree(buf);
584 buf = big_oops_buf;
585 size = unzipped_len;
586 compressed = false;
587 } else {
588 pr_err("decompression failed;returned %d\n",
589 unzipped_len);
590 compressed = true;
591 }
592 }
593 rc = pstore_mkfile(type, psi->name, id, count, buf,
594 compressed, (size_t)size, time, psi);
595 if (unzipped_len < 0) {
596 /* Free buffer other than big oops */
597 kfree(buf);
598 buf = NULL;
599 } else
600 unzipped_len = -1;
601 if (rc && (rc != -EEXIST || !quiet))
602 failed++;
603 }
604 if (psi->close)
605 psi->close(psi);
606 out:
607 mutex_unlock(&psi->read_mutex);
608
609 if (failed)
610 pr_warn("failed to load %d record(s) from '%s'\n",
611 failed, psi->name);
612 }
613
pstore_dowork(struct work_struct * work)614 static void pstore_dowork(struct work_struct *work)
615 {
616 pstore_get_records(1);
617 }
618
pstore_timefunc(unsigned long dummy)619 static void pstore_timefunc(unsigned long dummy)
620 {
621 if (pstore_new_entry) {
622 pstore_new_entry = 0;
623 schedule_work(&pstore_work);
624 }
625
626 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
627 }
628
629 module_param(backend, charp, 0444);
630 MODULE_PARM_DESC(backend, "Pstore backend to use");
631