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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Persistent Storage - platform driver interface parts.
4 *
5 * Copyright (C) 2007-2008 Google, Inc.
6 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
7 */
8
9#define pr_fmt(fmt) "pstore: " fmt
10
11#include <linux/atomic.h>
12#include <linux/types.h>
13#include <linux/errno.h>
14#include <linux/init.h>
15#include <linux/kmsg_dump.h>
16#include <linux/console.h>
17#include <linux/module.h>
18#include <linux/pstore.h>
19#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
20#include <linux/lzo.h>
21#endif
22#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
23#include <linux/lz4.h>
24#endif
25#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
26#include <linux/zstd.h>
27#endif
28#include <linux/crypto.h>
29#include <linux/string.h>
30#include <linux/timer.h>
31#include <linux/slab.h>
32#include <linux/uaccess.h>
33#include <linux/jiffies.h>
34#include <linux/workqueue.h>
35
36#include "internal.h"
37
38/*
39 * We defer making "oops" entries appear in pstore - see
40 * whether the system is actually still running well enough
41 * to let someone see the entry
42 */
43static int pstore_update_ms = -1;
44module_param_named(update_ms, pstore_update_ms, int, 0600);
45MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
46 "(default is -1, which means runtime updates are disabled; "
47 "enabling this option may not be safe; it may lead to further "
48 "corruption on Oopses)");
49
50/* Names should be in the same order as the enum pstore_type_id */
51static const char * const pstore_type_names[] = {
52 "dmesg",
53 "mce",
54 "console",
55 "ftrace",
56 "rtas",
57 "powerpc-ofw",
58 "powerpc-common",
59 "pmsg",
60 "powerpc-opal",
61};
62
63static int pstore_new_entry;
64
65static void pstore_timefunc(struct timer_list *);
66static DEFINE_TIMER(pstore_timer, pstore_timefunc);
67
68static void pstore_dowork(struct work_struct *);
69static DECLARE_WORK(pstore_work, pstore_dowork);
70
71/*
72 * psinfo_lock protects "psinfo" during calls to
73 * pstore_register(), pstore_unregister(), and
74 * the filesystem mount/unmount routines.
75 */
76static DEFINE_MUTEX(psinfo_lock);
77struct pstore_info *psinfo;
78
79static char *backend;
80module_param(backend, charp, 0444);
81MODULE_PARM_DESC(backend, "specific backend to use");
82
83static char *compress =
84#ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
85 CONFIG_PSTORE_COMPRESS_DEFAULT;
86#else
87 NULL;
88#endif
89module_param(compress, charp, 0444);
90MODULE_PARM_DESC(compress, "compression to use");
91
92/* How much of the kernel log to snapshot */
93unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
94module_param(kmsg_bytes, ulong, 0444);
95MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
96
97/* Compression parameters */
98static struct crypto_comp *tfm;
99
100struct pstore_zbackend {
101 int (*zbufsize)(size_t size);
102 const char *name;
103};
104
105static char *big_oops_buf;
106static size_t big_oops_buf_sz;
107
108void pstore_set_kmsg_bytes(int bytes)
109{
110 kmsg_bytes = bytes;
111}
112
113/* Tag each group of saved records with a sequence number */
114static int oopscount;
115
116const char *pstore_type_to_name(enum pstore_type_id type)
117{
118 BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
119
120 if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
121 return "unknown";
122
123 return pstore_type_names[type];
124}
125EXPORT_SYMBOL_GPL(pstore_type_to_name);
126
127enum pstore_type_id pstore_name_to_type(const char *name)
128{
129 int i;
130
131 for (i = 0; i < PSTORE_TYPE_MAX; i++) {
132 if (!strcmp(pstore_type_names[i], name))
133 return i;
134 }
135
136 return PSTORE_TYPE_MAX;
137}
138EXPORT_SYMBOL_GPL(pstore_name_to_type);
139
140static void pstore_timer_kick(void)
141{
142 if (pstore_update_ms < 0)
143 return;
144
145 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
146}
147
148static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
149{
150 /*
151 * In case of NMI path, pstore shouldn't be blocked
152 * regardless of reason.
153 */
154 if (in_nmi())
155 return true;
156
157 switch (reason) {
158 /* In panic case, other cpus are stopped by smp_send_stop(). */
159 case KMSG_DUMP_PANIC:
160 /*
161 * Emergency restart shouldn't be blocked by spinning on
162 * pstore_info::buf_lock.
163 */
164 case KMSG_DUMP_EMERG:
165 return true;
166 default:
167 return false;
168 }
169}
170
171#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
172static int zbufsize_deflate(size_t size)
173{
174 size_t cmpr;
175
176 switch (size) {
177 /* buffer range for efivars */
178 case 1000 ... 2000:
179 cmpr = 56;
180 break;
181 case 2001 ... 3000:
182 cmpr = 54;
183 break;
184 case 3001 ... 3999:
185 cmpr = 52;
186 break;
187 /* buffer range for nvram, erst */
188 case 4000 ... 10000:
189 cmpr = 45;
190 break;
191 default:
192 cmpr = 60;
193 break;
194 }
195
196 return (size * 100) / cmpr;
197}
198#endif
199
200#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
201static int zbufsize_lzo(size_t size)
202{
203 return lzo1x_worst_compress(size);
204}
205#endif
206
207#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
208static int zbufsize_lz4(size_t size)
209{
210 return LZ4_compressBound(size);
211}
212#endif
213
214#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
215static int zbufsize_842(size_t size)
216{
217 return size;
218}
219#endif
220
221#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
222static int zbufsize_zstd(size_t size)
223{
224 return zstd_compress_bound(size);
225}
226#endif
227
228static const struct pstore_zbackend *zbackend __ro_after_init;
229
230static const struct pstore_zbackend zbackends[] = {
231#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
232 {
233 .zbufsize = zbufsize_deflate,
234 .name = "deflate",
235 },
236#endif
237#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
238 {
239 .zbufsize = zbufsize_lzo,
240 .name = "lzo",
241 },
242#endif
243#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
244 {
245 .zbufsize = zbufsize_lz4,
246 .name = "lz4",
247 },
248#endif
249#if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
250 {
251 .zbufsize = zbufsize_lz4,
252 .name = "lz4hc",
253 },
254#endif
255#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
256 {
257 .zbufsize = zbufsize_842,
258 .name = "842",
259 },
260#endif
261#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
262 {
263 .zbufsize = zbufsize_zstd,
264 .name = "zstd",
265 },
266#endif
267 { }
268};
269
270static int pstore_compress(const void *in, void *out,
271 unsigned int inlen, unsigned int outlen)
272{
273 int ret;
274
275 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
276 return -EINVAL;
277
278 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
279 if (ret) {
280 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
281 return ret;
282 }
283
284 return outlen;
285}
286
287static void allocate_buf_for_compression(void)
288{
289 struct crypto_comp *ctx;
290 int size;
291 char *buf;
292
293 /* Skip if not built-in or compression backend not selected yet. */
294 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
295 return;
296
297 /* Skip if no pstore backend yet or compression init already done. */
298 if (!psinfo || tfm)
299 return;
300
301 if (!crypto_has_comp(zbackend->name, 0, 0)) {
302 pr_err("Unknown compression: %s\n", zbackend->name);
303 return;
304 }
305
306 size = zbackend->zbufsize(psinfo->bufsize);
307 if (size <= 0) {
308 pr_err("Invalid compression size for %s: %d\n",
309 zbackend->name, size);
310 return;
311 }
312
313 buf = kmalloc(size, GFP_KERNEL);
314 if (!buf) {
315 pr_err("Failed %d byte compression buffer allocation for: %s\n",
316 size, zbackend->name);
317 return;
318 }
319
320 ctx = crypto_alloc_comp(zbackend->name, 0, 0);
321 if (IS_ERR_OR_NULL(ctx)) {
322 kfree(buf);
323 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
324 PTR_ERR(ctx));
325 return;
326 }
327
328 /* A non-NULL big_oops_buf indicates compression is available. */
329 tfm = ctx;
330 big_oops_buf_sz = size;
331 big_oops_buf = buf;
332
333 pr_info("Using crash dump compression: %s\n", zbackend->name);
334}
335
336static void free_buf_for_compression(void)
337{
338 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
339 crypto_free_comp(tfm);
340 tfm = NULL;
341 }
342 kfree(big_oops_buf);
343 big_oops_buf = NULL;
344 big_oops_buf_sz = 0;
345}
346
347/*
348 * Called when compression fails, since the printk buffer
349 * would be fetched for compression calling it again when
350 * compression fails would have moved the iterator of
351 * printk buffer which results in fetching old contents.
352 * Copy the recent messages from big_oops_buf to psinfo->buf
353 */
354static size_t copy_kmsg_to_buffer(int hsize, size_t len)
355{
356 size_t total_len;
357 size_t diff;
358
359 total_len = hsize + len;
360
361 if (total_len > psinfo->bufsize) {
362 diff = total_len - psinfo->bufsize + hsize;
363 memcpy(psinfo->buf, big_oops_buf, hsize);
364 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
365 psinfo->bufsize - hsize);
366 total_len = psinfo->bufsize;
367 } else
368 memcpy(psinfo->buf, big_oops_buf, total_len);
369
370 return total_len;
371}
372
373void pstore_record_init(struct pstore_record *record,
374 struct pstore_info *psinfo)
375{
376 memset(record, 0, sizeof(*record));
377
378 record->psi = psinfo;
379
380 /* Report zeroed timestamp if called before timekeeping has resumed. */
381 record->time = ns_to_timespec64(ktime_get_real_fast_ns());
382}
383
384/*
385 * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
386 * end of the buffer.
387 */
388static void pstore_dump(struct kmsg_dumper *dumper,
389 enum kmsg_dump_reason reason)
390{
391 struct kmsg_dump_iter iter;
392 unsigned long total = 0;
393 const char *why;
394 unsigned int part = 1;
395 unsigned long flags = 0;
396 int saved_ret = 0;
397 int ret;
398
399 why = kmsg_dump_reason_str(reason);
400
401 if (pstore_cannot_block_path(reason)) {
402 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
403 pr_err("dump skipped in %s path because of concurrent dump\n",
404 in_nmi() ? "NMI" : why);
405 return;
406 }
407 } else {
408 spin_lock_irqsave(&psinfo->buf_lock, flags);
409 }
410
411 kmsg_dump_rewind(&iter);
412
413 oopscount++;
414 while (total < kmsg_bytes) {
415 char *dst;
416 size_t dst_size;
417 int header_size;
418 int zipped_len = -1;
419 size_t dump_size;
420 struct pstore_record record;
421
422 pstore_record_init(&record, psinfo);
423 record.type = PSTORE_TYPE_DMESG;
424 record.count = oopscount;
425 record.reason = reason;
426 record.part = part;
427 record.buf = psinfo->buf;
428
429 if (big_oops_buf) {
430 dst = big_oops_buf;
431 dst_size = big_oops_buf_sz;
432 } else {
433 dst = psinfo->buf;
434 dst_size = psinfo->bufsize;
435 }
436
437 /* Write dump header. */
438 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
439 oopscount, part);
440 dst_size -= header_size;
441
442 /* Write dump contents. */
443 if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
444 dst_size, &dump_size))
445 break;
446
447 if (big_oops_buf) {
448 zipped_len = pstore_compress(dst, psinfo->buf,
449 header_size + dump_size,
450 psinfo->bufsize);
451
452 if (zipped_len > 0) {
453 record.compressed = true;
454 record.size = zipped_len;
455 } else {
456 record.size = copy_kmsg_to_buffer(header_size,
457 dump_size);
458 }
459 } else {
460 record.size = header_size + dump_size;
461 }
462
463 ret = psinfo->write(&record);
464 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
465 pstore_new_entry = 1;
466 pstore_timer_kick();
467 } else {
468 /* Preserve only the first non-zero returned value. */
469 if (!saved_ret)
470 saved_ret = ret;
471 }
472
473 total += record.size;
474 part++;
475 }
476 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
477
478 if (saved_ret) {
479 pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
480 saved_ret);
481 }
482}
483
484static struct kmsg_dumper pstore_dumper = {
485 .dump = pstore_dump,
486};
487
488/*
489 * Register with kmsg_dump to save last part of console log on panic.
490 */
491static void pstore_register_kmsg(void)
492{
493 kmsg_dump_register(&pstore_dumper);
494}
495
496static void pstore_unregister_kmsg(void)
497{
498 kmsg_dump_unregister(&pstore_dumper);
499}
500
501#ifdef CONFIG_PSTORE_CONSOLE
502static void pstore_console_write(struct console *con, const char *s, unsigned c)
503{
504 struct pstore_record record;
505
506 if (!c)
507 return;
508
509 pstore_record_init(&record, psinfo);
510 record.type = PSTORE_TYPE_CONSOLE;
511
512 record.buf = (char *)s;
513 record.size = c;
514 psinfo->write(&record);
515}
516
517static struct console pstore_console = {
518 .write = pstore_console_write,
519 .index = -1,
520};
521
522static void pstore_register_console(void)
523{
524 /* Show which backend is going to get console writes. */
525 strscpy(pstore_console.name, psinfo->name,
526 sizeof(pstore_console.name));
527 /*
528 * Always initialize flags here since prior unregister_console()
529 * calls may have changed settings (specifically CON_ENABLED).
530 */
531 pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
532 register_console(&pstore_console);
533}
534
535static void pstore_unregister_console(void)
536{
537 unregister_console(&pstore_console);
538}
539#else
540static void pstore_register_console(void) {}
541static void pstore_unregister_console(void) {}
542#endif
543
544static int pstore_write_user_compat(struct pstore_record *record,
545 const char __user *buf)
546{
547 int ret = 0;
548
549 if (record->buf)
550 return -EINVAL;
551
552 record->buf = memdup_user(buf, record->size);
553 if (IS_ERR(record->buf)) {
554 ret = PTR_ERR(record->buf);
555 goto out;
556 }
557
558 ret = record->psi->write(record);
559
560 kfree(record->buf);
561out:
562 record->buf = NULL;
563
564 return unlikely(ret < 0) ? ret : record->size;
565}
566
567/*
568 * platform specific persistent storage driver registers with
569 * us here. If pstore is already mounted, call the platform
570 * read function right away to populate the file system. If not
571 * then the pstore mount code will call us later to fill out
572 * the file system.
573 */
574int pstore_register(struct pstore_info *psi)
575{
576 if (backend && strcmp(backend, psi->name)) {
577 pr_warn("backend '%s' already in use: ignoring '%s'\n",
578 backend, psi->name);
579 return -EBUSY;
580 }
581
582 /* Sanity check flags. */
583 if (!psi->flags) {
584 pr_warn("backend '%s' must support at least one frontend\n",
585 psi->name);
586 return -EINVAL;
587 }
588
589 /* Check for required functions. */
590 if (!psi->read || !psi->write) {
591 pr_warn("backend '%s' must implement read() and write()\n",
592 psi->name);
593 return -EINVAL;
594 }
595
596 mutex_lock(&psinfo_lock);
597 if (psinfo) {
598 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
599 psinfo->name, psi->name);
600 mutex_unlock(&psinfo_lock);
601 return -EBUSY;
602 }
603
604 if (!psi->write_user)
605 psi->write_user = pstore_write_user_compat;
606 psinfo = psi;
607 mutex_init(&psinfo->read_mutex);
608 spin_lock_init(&psinfo->buf_lock);
609
610 if (psi->flags & PSTORE_FLAGS_DMESG)
611 allocate_buf_for_compression();
612
613 pstore_get_records(0);
614
615 if (psi->flags & PSTORE_FLAGS_DMESG) {
616 pstore_dumper.max_reason = psinfo->max_reason;
617 pstore_register_kmsg();
618 }
619 if (psi->flags & PSTORE_FLAGS_CONSOLE)
620 pstore_register_console();
621 if (psi->flags & PSTORE_FLAGS_FTRACE)
622 pstore_register_ftrace();
623 if (psi->flags & PSTORE_FLAGS_PMSG)
624 pstore_register_pmsg();
625
626 /* Start watching for new records, if desired. */
627 pstore_timer_kick();
628
629 /*
630 * Update the module parameter backend, so it is visible
631 * through /sys/module/pstore/parameters/backend
632 */
633 backend = kstrdup(psi->name, GFP_KERNEL);
634
635 pr_info("Registered %s as persistent store backend\n", psi->name);
636
637 mutex_unlock(&psinfo_lock);
638 return 0;
639}
640EXPORT_SYMBOL_GPL(pstore_register);
641
642void pstore_unregister(struct pstore_info *psi)
643{
644 /* It's okay to unregister nothing. */
645 if (!psi)
646 return;
647
648 mutex_lock(&psinfo_lock);
649
650 /* Only one backend can be registered at a time. */
651 if (WARN_ON(psi != psinfo)) {
652 mutex_unlock(&psinfo_lock);
653 return;
654 }
655
656 /* Unregister all callbacks. */
657 if (psi->flags & PSTORE_FLAGS_PMSG)
658 pstore_unregister_pmsg();
659 if (psi->flags & PSTORE_FLAGS_FTRACE)
660 pstore_unregister_ftrace();
661 if (psi->flags & PSTORE_FLAGS_CONSOLE)
662 pstore_unregister_console();
663 if (psi->flags & PSTORE_FLAGS_DMESG)
664 pstore_unregister_kmsg();
665
666 /* Stop timer and make sure all work has finished. */
667 del_timer_sync(&pstore_timer);
668 flush_work(&pstore_work);
669
670 /* Remove all backend records from filesystem tree. */
671 pstore_put_backend_records(psi);
672
673 free_buf_for_compression();
674
675 psinfo = NULL;
676 kfree(backend);
677 backend = NULL;
678
679 pr_info("Unregistered %s as persistent store backend\n", psi->name);
680 mutex_unlock(&psinfo_lock);
681}
682EXPORT_SYMBOL_GPL(pstore_unregister);
683
684static void decompress_record(struct pstore_record *record)
685{
686 int ret;
687 int unzipped_len;
688 char *unzipped, *workspace;
689
690 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
691 return;
692
693 /* Only PSTORE_TYPE_DMESG support compression. */
694 if (record->type != PSTORE_TYPE_DMESG) {
695 pr_warn("ignored compressed record type %d\n", record->type);
696 return;
697 }
698
699 /* Missing compression buffer means compression was not initialized. */
700 if (!big_oops_buf) {
701 pr_warn("no decompression method initialized!\n");
702 return;
703 }
704
705 /* Allocate enough space to hold max decompression and ECC. */
706 unzipped_len = big_oops_buf_sz;
707 workspace = kmalloc(unzipped_len + record->ecc_notice_size,
708 GFP_KERNEL);
709 if (!workspace)
710 return;
711
712 /* After decompression "unzipped_len" is almost certainly smaller. */
713 ret = crypto_comp_decompress(tfm, record->buf, record->size,
714 workspace, &unzipped_len);
715 if (ret) {
716 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
717 kfree(workspace);
718 return;
719 }
720
721 /* Append ECC notice to decompressed buffer. */
722 memcpy(workspace + unzipped_len, record->buf + record->size,
723 record->ecc_notice_size);
724
725 /* Copy decompressed contents into an minimum-sized allocation. */
726 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
727 GFP_KERNEL);
728 kfree(workspace);
729 if (!unzipped)
730 return;
731
732 /* Swap out compressed contents with decompressed contents. */
733 kfree(record->buf);
734 record->buf = unzipped;
735 record->size = unzipped_len;
736 record->compressed = false;
737}
738
739/*
740 * Read all the records from one persistent store backend. Create
741 * files in our filesystem. Don't warn about -EEXIST errors
742 * when we are re-scanning the backing store looking to add new
743 * error records.
744 */
745void pstore_get_backend_records(struct pstore_info *psi,
746 struct dentry *root, int quiet)
747{
748 int failed = 0;
749 unsigned int stop_loop = 65536;
750
751 if (!psi || !root)
752 return;
753
754 mutex_lock(&psi->read_mutex);
755 if (psi->open && psi->open(psi))
756 goto out;
757
758 /*
759 * Backend callback read() allocates record.buf. decompress_record()
760 * may reallocate record.buf. On success, pstore_mkfile() will keep
761 * the record.buf, so free it only on failure.
762 */
763 for (; stop_loop; stop_loop--) {
764 struct pstore_record *record;
765 int rc;
766
767 record = kzalloc(sizeof(*record), GFP_KERNEL);
768 if (!record) {
769 pr_err("out of memory creating record\n");
770 break;
771 }
772 pstore_record_init(record, psi);
773
774 record->size = psi->read(record);
775
776 /* No more records left in backend? */
777 if (record->size <= 0) {
778 kfree(record);
779 break;
780 }
781
782 decompress_record(record);
783 rc = pstore_mkfile(root, record);
784 if (rc) {
785 /* pstore_mkfile() did not take record, so free it. */
786 kfree(record->buf);
787 kfree(record->priv);
788 kfree(record);
789 if (rc != -EEXIST || !quiet)
790 failed++;
791 }
792 }
793 if (psi->close)
794 psi->close(psi);
795out:
796 mutex_unlock(&psi->read_mutex);
797
798 if (failed)
799 pr_warn("failed to create %d record(s) from '%s'\n",
800 failed, psi->name);
801 if (!stop_loop)
802 pr_err("looping? Too many records seen from '%s'\n",
803 psi->name);
804}
805
806static void pstore_dowork(struct work_struct *work)
807{
808 pstore_get_records(1);
809}
810
811static void pstore_timefunc(struct timer_list *unused)
812{
813 if (pstore_new_entry) {
814 pstore_new_entry = 0;
815 schedule_work(&pstore_work);
816 }
817
818 pstore_timer_kick();
819}
820
821static void __init pstore_choose_compression(void)
822{
823 const struct pstore_zbackend *step;
824
825 if (!compress)
826 return;
827
828 for (step = zbackends; step->name; step++) {
829 if (!strcmp(compress, step->name)) {
830 zbackend = step;
831 return;
832 }
833 }
834}
835
836static int __init pstore_init(void)
837{
838 int ret;
839
840 pstore_choose_compression();
841
842 /*
843 * Check if any pstore backends registered earlier but did not
844 * initialize compression because crypto was not ready. If so,
845 * initialize compression now.
846 */
847 allocate_buf_for_compression();
848
849 ret = pstore_init_fs();
850 if (ret)
851 free_buf_for_compression();
852
853 return ret;
854}
855late_initcall(pstore_init);
856
857static void __exit pstore_exit(void)
858{
859 pstore_exit_fs();
860}
861module_exit(pstore_exit)
862
863MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
864MODULE_LICENSE("GPL");
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 */
47static int pstore_update_ms = -1;
48module_param_named(update_ms, pstore_update_ms, int, 0600);
49MODULE_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
54static int pstore_new_entry;
55
56static void pstore_timefunc(unsigned long);
57static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
58
59static void pstore_dowork(struct work_struct *);
60static DECLARE_WORK(pstore_work, pstore_dowork);
61
62/*
63 * pstore_lock just protects "psinfo" during
64 * calls to pstore_register()
65 */
66static DEFINE_SPINLOCK(pstore_lock);
67struct pstore_info *psinfo;
68
69static char *backend;
70
71/* Compression parameters */
72#define COMPR_LEVEL 6
73#define WINDOW_BITS 12
74#define MEM_LEVEL 4
75static struct z_stream_s stream;
76
77static char *big_oops_buf;
78static size_t big_oops_buf_sz;
79
80/* How much of the console log to snapshot */
81static unsigned long kmsg_bytes = 10240;
82
83void pstore_set_kmsg_bytes(int bytes)
84{
85 kmsg_bytes = bytes;
86}
87
88/* Tag each group of saved records with a sequence number */
89static int oopscount;
90
91static 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
111bool 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}
130EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
131
132/* Derived from logfs_compress() */
133static 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;
163error:
164 return ret;
165}
166
167/* Derived from logfs_uncompress */
168static 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;
193error:
194 return ret;
195}
196
197static 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
240static 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 */
255static 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 */
279static 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
360static 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 */
367static void pstore_register_kmsg(void)
368{
369 kmsg_dump_register(&pstore_dumper);
370}
371
372static void pstore_unregister_kmsg(void)
373{
374 kmsg_dump_unregister(&pstore_dumper);
375}
376
377#ifdef CONFIG_PSTORE_CONSOLE
378static 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 memcpy(psinfo->buf, s, c);
396 psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
397 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
398 s += c;
399 c = e - s;
400 }
401}
402
403static 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
410static void pstore_register_console(void)
411{
412 register_console(&pstore_console);
413}
414
415static void pstore_unregister_console(void)
416{
417 unregister_console(&pstore_console);
418}
419#else
420static void pstore_register_console(void) {}
421static void pstore_unregister_console(void) {}
422#endif
423
424static 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
434/*
435 * platform specific persistent storage driver registers with
436 * us here. If pstore is already mounted, call the platform
437 * read function right away to populate the file system. If not
438 * then the pstore mount code will call us later to fill out
439 * the file system.
440 */
441int pstore_register(struct pstore_info *psi)
442{
443 struct module *owner = psi->owner;
444
445 if (backend && strcmp(backend, psi->name))
446 return -EPERM;
447
448 spin_lock(&pstore_lock);
449 if (psinfo) {
450 spin_unlock(&pstore_lock);
451 return -EBUSY;
452 }
453
454 if (!psi->write)
455 psi->write = pstore_write_compat;
456 psinfo = psi;
457 mutex_init(&psinfo->read_mutex);
458 spin_unlock(&pstore_lock);
459
460 if (owner && !try_module_get(owner)) {
461 psinfo = NULL;
462 return -EINVAL;
463 }
464
465 allocate_buf_for_compression();
466
467 if (pstore_is_mounted())
468 pstore_get_records(0);
469
470 pstore_register_kmsg();
471
472 if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
473 pstore_register_console();
474 pstore_register_ftrace();
475 pstore_register_pmsg();
476 }
477
478 if (pstore_update_ms >= 0) {
479 pstore_timer.expires = jiffies +
480 msecs_to_jiffies(pstore_update_ms);
481 add_timer(&pstore_timer);
482 }
483
484 /*
485 * Update the module parameter backend, so it is visible
486 * through /sys/module/pstore/parameters/backend
487 */
488 backend = psi->name;
489
490 module_put(owner);
491
492 pr_info("Registered %s as persistent store backend\n", psi->name);
493
494 return 0;
495}
496EXPORT_SYMBOL_GPL(pstore_register);
497
498void pstore_unregister(struct pstore_info *psi)
499{
500 pstore_unregister_pmsg();
501 pstore_unregister_ftrace();
502 pstore_unregister_console();
503 pstore_unregister_kmsg();
504
505 free_buf_for_compression();
506
507 psinfo = NULL;
508 backend = NULL;
509}
510EXPORT_SYMBOL_GPL(pstore_unregister);
511
512/*
513 * Read all the records from the persistent store. Create
514 * files in our filesystem. Don't warn about -EEXIST errors
515 * when we are re-scanning the backing store looking to add new
516 * error records.
517 */
518void pstore_get_records(int quiet)
519{
520 struct pstore_info *psi = psinfo;
521 char *buf = NULL;
522 ssize_t size;
523 u64 id;
524 int count;
525 enum pstore_type_id type;
526 struct timespec time;
527 int failed = 0, rc;
528 bool compressed;
529 int unzipped_len = -1;
530
531 if (!psi)
532 return;
533
534 mutex_lock(&psi->read_mutex);
535 if (psi->open && psi->open(psi))
536 goto out;
537
538 while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
539 psi)) > 0) {
540 if (compressed && (type == PSTORE_TYPE_DMESG)) {
541 if (big_oops_buf)
542 unzipped_len = pstore_decompress(buf,
543 big_oops_buf, size,
544 big_oops_buf_sz);
545
546 if (unzipped_len > 0) {
547 kfree(buf);
548 buf = big_oops_buf;
549 size = unzipped_len;
550 compressed = false;
551 } else {
552 pr_err("decompression failed;returned %d\n",
553 unzipped_len);
554 compressed = true;
555 }
556 }
557 rc = pstore_mkfile(type, psi->name, id, count, buf,
558 compressed, (size_t)size, time, psi);
559 if (unzipped_len < 0) {
560 /* Free buffer other than big oops */
561 kfree(buf);
562 buf = NULL;
563 } else
564 unzipped_len = -1;
565 if (rc && (rc != -EEXIST || !quiet))
566 failed++;
567 }
568 if (psi->close)
569 psi->close(psi);
570out:
571 mutex_unlock(&psi->read_mutex);
572
573 if (failed)
574 pr_warn("failed to load %d record(s) from '%s'\n",
575 failed, psi->name);
576}
577
578static void pstore_dowork(struct work_struct *work)
579{
580 pstore_get_records(1);
581}
582
583static void pstore_timefunc(unsigned long dummy)
584{
585 if (pstore_new_entry) {
586 pstore_new_entry = 0;
587 schedule_work(&pstore_work);
588 }
589
590 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
591}
592
593module_param(backend, charp, 0444);
594MODULE_PARM_DESC(backend, "Pstore backend to use");