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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#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
32#include <linux/lzo.h>
33#endif
34#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
35#include <linux/lz4.h>
36#endif
37#include <linux/crypto.h>
38#include <linux/string.h>
39#include <linux/timer.h>
40#include <linux/slab.h>
41#include <linux/uaccess.h>
42#include <linux/jiffies.h>
43#include <linux/workqueue.h>
44
45#include "internal.h"
46
47/*
48 * We defer making "oops" entries appear in pstore - see
49 * whether the system is actually still running well enough
50 * to let someone see the entry
51 */
52static int pstore_update_ms = -1;
53module_param_named(update_ms, pstore_update_ms, int, 0600);
54MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
55 "(default is -1, which means runtime updates are disabled; "
56 "enabling this option is not safe, it may lead to further "
57 "corruption on Oopses)");
58
59static int pstore_new_entry;
60
61static void pstore_timefunc(struct timer_list *);
62static DEFINE_TIMER(pstore_timer, pstore_timefunc);
63
64static void pstore_dowork(struct work_struct *);
65static DECLARE_WORK(pstore_work, pstore_dowork);
66
67/*
68 * pstore_lock just protects "psinfo" during
69 * calls to pstore_register()
70 */
71static DEFINE_SPINLOCK(pstore_lock);
72struct pstore_info *psinfo;
73
74static char *backend;
75static char *compress =
76#ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
77 CONFIG_PSTORE_COMPRESS_DEFAULT;
78#else
79 NULL;
80#endif
81
82/* Compression parameters */
83static struct crypto_comp *tfm;
84
85struct pstore_zbackend {
86 int (*zbufsize)(size_t size);
87 const char *name;
88};
89
90static char *big_oops_buf;
91static size_t big_oops_buf_sz;
92
93/* How much of the console log to snapshot */
94unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
95
96void pstore_set_kmsg_bytes(int bytes)
97{
98 kmsg_bytes = bytes;
99}
100
101/* Tag each group of saved records with a sequence number */
102static int oopscount;
103
104static const char *get_reason_str(enum kmsg_dump_reason reason)
105{
106 switch (reason) {
107 case KMSG_DUMP_PANIC:
108 return "Panic";
109 case KMSG_DUMP_OOPS:
110 return "Oops";
111 case KMSG_DUMP_EMERG:
112 return "Emergency";
113 case KMSG_DUMP_RESTART:
114 return "Restart";
115 case KMSG_DUMP_HALT:
116 return "Halt";
117 case KMSG_DUMP_POWEROFF:
118 return "Poweroff";
119 default:
120 return "Unknown";
121 }
122}
123
124bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
125{
126 /*
127 * In case of NMI path, pstore shouldn't be blocked
128 * regardless of reason.
129 */
130 if (in_nmi())
131 return true;
132
133 switch (reason) {
134 /* In panic case, other cpus are stopped by smp_send_stop(). */
135 case KMSG_DUMP_PANIC:
136 /* Emergency restart shouldn't be blocked by spin lock. */
137 case KMSG_DUMP_EMERG:
138 return true;
139 default:
140 return false;
141 }
142}
143EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
144
145#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
146static int zbufsize_deflate(size_t size)
147{
148 size_t cmpr;
149
150 switch (size) {
151 /* buffer range for efivars */
152 case 1000 ... 2000:
153 cmpr = 56;
154 break;
155 case 2001 ... 3000:
156 cmpr = 54;
157 break;
158 case 3001 ... 3999:
159 cmpr = 52;
160 break;
161 /* buffer range for nvram, erst */
162 case 4000 ... 10000:
163 cmpr = 45;
164 break;
165 default:
166 cmpr = 60;
167 break;
168 }
169
170 return (size * 100) / cmpr;
171}
172#endif
173
174#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
175static int zbufsize_lzo(size_t size)
176{
177 return lzo1x_worst_compress(size);
178}
179#endif
180
181#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
182static int zbufsize_lz4(size_t size)
183{
184 return LZ4_compressBound(size);
185}
186#endif
187
188#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
189static int zbufsize_842(size_t size)
190{
191 return size;
192}
193#endif
194
195static const struct pstore_zbackend *zbackend __ro_after_init;
196
197static const struct pstore_zbackend zbackends[] = {
198#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
199 {
200 .zbufsize = zbufsize_deflate,
201 .name = "deflate",
202 },
203#endif
204#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
205 {
206 .zbufsize = zbufsize_lzo,
207 .name = "lzo",
208 },
209#endif
210#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
211 {
212 .zbufsize = zbufsize_lz4,
213 .name = "lz4",
214 },
215#endif
216#if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
217 {
218 .zbufsize = zbufsize_lz4,
219 .name = "lz4hc",
220 },
221#endif
222#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
223 {
224 .zbufsize = zbufsize_842,
225 .name = "842",
226 },
227#endif
228 { }
229};
230
231static int pstore_compress(const void *in, void *out,
232 unsigned int inlen, unsigned int outlen)
233{
234 int ret;
235
236 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
237 if (ret) {
238 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
239 return ret;
240 }
241
242 return outlen;
243}
244
245static int pstore_decompress(void *in, void *out,
246 unsigned int inlen, unsigned int outlen)
247{
248 int ret;
249
250 ret = crypto_comp_decompress(tfm, in, inlen, out, &outlen);
251 if (ret) {
252 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
253 return ret;
254 }
255
256 return outlen;
257}
258
259static void allocate_buf_for_compression(void)
260{
261 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
262 return;
263
264 if (!crypto_has_comp(zbackend->name, 0, 0)) {
265 pr_err("No %s compression\n", zbackend->name);
266 return;
267 }
268
269 big_oops_buf_sz = zbackend->zbufsize(psinfo->bufsize);
270 if (big_oops_buf_sz <= 0)
271 return;
272
273 big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
274 if (!big_oops_buf) {
275 pr_err("allocate compression buffer error!\n");
276 return;
277 }
278
279 tfm = crypto_alloc_comp(zbackend->name, 0, 0);
280 if (IS_ERR_OR_NULL(tfm)) {
281 kfree(big_oops_buf);
282 big_oops_buf = NULL;
283 pr_err("crypto_alloc_comp() failed!\n");
284 return;
285 }
286}
287
288static void free_buf_for_compression(void)
289{
290 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && !IS_ERR_OR_NULL(tfm))
291 crypto_free_comp(tfm);
292 kfree(big_oops_buf);
293 big_oops_buf = NULL;
294 big_oops_buf_sz = 0;
295}
296
297/*
298 * Called when compression fails, since the printk buffer
299 * would be fetched for compression calling it again when
300 * compression fails would have moved the iterator of
301 * printk buffer which results in fetching old contents.
302 * Copy the recent messages from big_oops_buf to psinfo->buf
303 */
304static size_t copy_kmsg_to_buffer(int hsize, size_t len)
305{
306 size_t total_len;
307 size_t diff;
308
309 total_len = hsize + len;
310
311 if (total_len > psinfo->bufsize) {
312 diff = total_len - psinfo->bufsize + hsize;
313 memcpy(psinfo->buf, big_oops_buf, hsize);
314 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
315 psinfo->bufsize - hsize);
316 total_len = psinfo->bufsize;
317 } else
318 memcpy(psinfo->buf, big_oops_buf, total_len);
319
320 return total_len;
321}
322
323void pstore_record_init(struct pstore_record *record,
324 struct pstore_info *psinfo)
325{
326 memset(record, 0, sizeof(*record));
327
328 record->psi = psinfo;
329
330 /* Report zeroed timestamp if called before timekeeping has resumed. */
331 record->time = ns_to_timespec(ktime_get_real_fast_ns());
332}
333
334/*
335 * callback from kmsg_dump. (s2,l2) has the most recently
336 * written bytes, older bytes are in (s1,l1). Save as much
337 * as we can from the end of the buffer.
338 */
339static void pstore_dump(struct kmsg_dumper *dumper,
340 enum kmsg_dump_reason reason)
341{
342 unsigned long total = 0;
343 const char *why;
344 unsigned int part = 1;
345 unsigned long flags = 0;
346 int is_locked;
347 int ret;
348
349 why = get_reason_str(reason);
350
351 if (pstore_cannot_block_path(reason)) {
352 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
353 if (!is_locked) {
354 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
355 , in_nmi() ? "NMI" : why);
356 return;
357 }
358 } else {
359 spin_lock_irqsave(&psinfo->buf_lock, flags);
360 is_locked = 1;
361 }
362 oopscount++;
363 while (total < kmsg_bytes) {
364 char *dst;
365 size_t dst_size;
366 int header_size;
367 int zipped_len = -1;
368 size_t dump_size;
369 struct pstore_record record;
370
371 pstore_record_init(&record, psinfo);
372 record.type = PSTORE_TYPE_DMESG;
373 record.count = oopscount;
374 record.reason = reason;
375 record.part = part;
376 record.buf = psinfo->buf;
377
378 if (big_oops_buf && is_locked) {
379 dst = big_oops_buf;
380 dst_size = big_oops_buf_sz;
381 } else {
382 dst = psinfo->buf;
383 dst_size = psinfo->bufsize;
384 }
385
386 /* Write dump header. */
387 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
388 oopscount, part);
389 dst_size -= header_size;
390
391 /* Write dump contents. */
392 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
393 dst_size, &dump_size))
394 break;
395
396 if (big_oops_buf && is_locked) {
397 zipped_len = pstore_compress(dst, psinfo->buf,
398 header_size + dump_size,
399 psinfo->bufsize);
400
401 if (zipped_len > 0) {
402 record.compressed = true;
403 record.size = zipped_len;
404 } else {
405 record.size = copy_kmsg_to_buffer(header_size,
406 dump_size);
407 }
408 } else {
409 record.size = header_size + dump_size;
410 }
411
412 ret = psinfo->write(&record);
413 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
414 pstore_new_entry = 1;
415
416 total += record.size;
417 part++;
418 }
419 if (is_locked)
420 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
421}
422
423static struct kmsg_dumper pstore_dumper = {
424 .dump = pstore_dump,
425};
426
427/*
428 * Register with kmsg_dump to save last part of console log on panic.
429 */
430static void pstore_register_kmsg(void)
431{
432 kmsg_dump_register(&pstore_dumper);
433}
434
435static void pstore_unregister_kmsg(void)
436{
437 kmsg_dump_unregister(&pstore_dumper);
438}
439
440#ifdef CONFIG_PSTORE_CONSOLE
441static void pstore_console_write(struct console *con, const char *s, unsigned c)
442{
443 const char *e = s + c;
444
445 while (s < e) {
446 struct pstore_record record;
447 unsigned long flags;
448
449 pstore_record_init(&record, psinfo);
450 record.type = PSTORE_TYPE_CONSOLE;
451
452 if (c > psinfo->bufsize)
453 c = psinfo->bufsize;
454
455 if (oops_in_progress) {
456 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
457 break;
458 } else {
459 spin_lock_irqsave(&psinfo->buf_lock, flags);
460 }
461 record.buf = (char *)s;
462 record.size = c;
463 psinfo->write(&record);
464 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
465 s += c;
466 c = e - s;
467 }
468}
469
470static struct console pstore_console = {
471 .name = "pstore",
472 .write = pstore_console_write,
473 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
474 .index = -1,
475};
476
477static void pstore_register_console(void)
478{
479 register_console(&pstore_console);
480}
481
482static void pstore_unregister_console(void)
483{
484 unregister_console(&pstore_console);
485}
486#else
487static void pstore_register_console(void) {}
488static void pstore_unregister_console(void) {}
489#endif
490
491static int pstore_write_user_compat(struct pstore_record *record,
492 const char __user *buf)
493{
494 int ret = 0;
495
496 if (record->buf)
497 return -EINVAL;
498
499 record->buf = memdup_user(buf, record->size);
500 if (IS_ERR(record->buf)) {
501 ret = PTR_ERR(record->buf);
502 goto out;
503 }
504
505 ret = record->psi->write(record);
506
507 kfree(record->buf);
508out:
509 record->buf = NULL;
510
511 return unlikely(ret < 0) ? ret : record->size;
512}
513
514/*
515 * platform specific persistent storage driver registers with
516 * us here. If pstore is already mounted, call the platform
517 * read function right away to populate the file system. If not
518 * then the pstore mount code will call us later to fill out
519 * the file system.
520 */
521int pstore_register(struct pstore_info *psi)
522{
523 struct module *owner = psi->owner;
524
525 if (backend && strcmp(backend, psi->name)) {
526 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
527 return -EPERM;
528 }
529
530 /* Sanity check flags. */
531 if (!psi->flags) {
532 pr_warn("backend '%s' must support at least one frontend\n",
533 psi->name);
534 return -EINVAL;
535 }
536
537 /* Check for required functions. */
538 if (!psi->read || !psi->write) {
539 pr_warn("backend '%s' must implement read() and write()\n",
540 psi->name);
541 return -EINVAL;
542 }
543
544 spin_lock(&pstore_lock);
545 if (psinfo) {
546 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
547 psinfo->name, psi->name);
548 spin_unlock(&pstore_lock);
549 return -EBUSY;
550 }
551
552 if (!psi->write_user)
553 psi->write_user = pstore_write_user_compat;
554 psinfo = psi;
555 mutex_init(&psinfo->read_mutex);
556 spin_unlock(&pstore_lock);
557
558 if (owner && !try_module_get(owner)) {
559 psinfo = NULL;
560 return -EINVAL;
561 }
562
563 allocate_buf_for_compression();
564
565 if (pstore_is_mounted())
566 pstore_get_records(0);
567
568 if (psi->flags & PSTORE_FLAGS_DMESG)
569 pstore_register_kmsg();
570 if (psi->flags & PSTORE_FLAGS_CONSOLE)
571 pstore_register_console();
572 if (psi->flags & PSTORE_FLAGS_FTRACE)
573 pstore_register_ftrace();
574 if (psi->flags & PSTORE_FLAGS_PMSG)
575 pstore_register_pmsg();
576
577 /* Start watching for new records, if desired. */
578 if (pstore_update_ms >= 0) {
579 pstore_timer.expires = jiffies +
580 msecs_to_jiffies(pstore_update_ms);
581 add_timer(&pstore_timer);
582 }
583
584 /*
585 * Update the module parameter backend, so it is visible
586 * through /sys/module/pstore/parameters/backend
587 */
588 backend = psi->name;
589
590 pr_info("Registered %s as persistent store backend\n", psi->name);
591
592 module_put(owner);
593
594 return 0;
595}
596EXPORT_SYMBOL_GPL(pstore_register);
597
598void pstore_unregister(struct pstore_info *psi)
599{
600 /* Stop timer and make sure all work has finished. */
601 pstore_update_ms = -1;
602 del_timer_sync(&pstore_timer);
603 flush_work(&pstore_work);
604
605 if (psi->flags & PSTORE_FLAGS_PMSG)
606 pstore_unregister_pmsg();
607 if (psi->flags & PSTORE_FLAGS_FTRACE)
608 pstore_unregister_ftrace();
609 if (psi->flags & PSTORE_FLAGS_CONSOLE)
610 pstore_unregister_console();
611 if (psi->flags & PSTORE_FLAGS_DMESG)
612 pstore_unregister_kmsg();
613
614 free_buf_for_compression();
615
616 psinfo = NULL;
617 backend = NULL;
618}
619EXPORT_SYMBOL_GPL(pstore_unregister);
620
621static void decompress_record(struct pstore_record *record)
622{
623 int unzipped_len;
624 char *decompressed;
625
626 if (!record->compressed)
627 return;
628
629 /* Only PSTORE_TYPE_DMESG support compression. */
630 if (record->type != PSTORE_TYPE_DMESG) {
631 pr_warn("ignored compressed record type %d\n", record->type);
632 return;
633 }
634
635 /* No compression method has created the common buffer. */
636 if (!big_oops_buf) {
637 pr_warn("no decompression buffer allocated\n");
638 return;
639 }
640
641 unzipped_len = pstore_decompress(record->buf, big_oops_buf,
642 record->size, big_oops_buf_sz);
643 if (unzipped_len <= 0) {
644 pr_err("decompression failed: %d\n", unzipped_len);
645 return;
646 }
647
648 /* Build new buffer for decompressed contents. */
649 decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
650 GFP_KERNEL);
651 if (!decompressed) {
652 pr_err("decompression ran out of memory\n");
653 return;
654 }
655 memcpy(decompressed, big_oops_buf, unzipped_len);
656
657 /* Append ECC notice to decompressed buffer. */
658 memcpy(decompressed + unzipped_len, record->buf + record->size,
659 record->ecc_notice_size);
660
661 /* Swap out compresed contents with decompressed contents. */
662 kfree(record->buf);
663 record->buf = decompressed;
664 record->size = unzipped_len;
665 record->compressed = false;
666}
667
668/*
669 * Read all the records from one persistent store backend. Create
670 * files in our filesystem. Don't warn about -EEXIST errors
671 * when we are re-scanning the backing store looking to add new
672 * error records.
673 */
674void pstore_get_backend_records(struct pstore_info *psi,
675 struct dentry *root, int quiet)
676{
677 int failed = 0;
678 unsigned int stop_loop = 65536;
679
680 if (!psi || !root)
681 return;
682
683 mutex_lock(&psi->read_mutex);
684 if (psi->open && psi->open(psi))
685 goto out;
686
687 /*
688 * Backend callback read() allocates record.buf. decompress_record()
689 * may reallocate record.buf. On success, pstore_mkfile() will keep
690 * the record.buf, so free it only on failure.
691 */
692 for (; stop_loop; stop_loop--) {
693 struct pstore_record *record;
694 int rc;
695
696 record = kzalloc(sizeof(*record), GFP_KERNEL);
697 if (!record) {
698 pr_err("out of memory creating record\n");
699 break;
700 }
701 pstore_record_init(record, psi);
702
703 record->size = psi->read(record);
704
705 /* No more records left in backend? */
706 if (record->size <= 0) {
707 kfree(record);
708 break;
709 }
710
711 decompress_record(record);
712 rc = pstore_mkfile(root, record);
713 if (rc) {
714 /* pstore_mkfile() did not take record, so free it. */
715 kfree(record->buf);
716 kfree(record);
717 if (rc != -EEXIST || !quiet)
718 failed++;
719 }
720 }
721 if (psi->close)
722 psi->close(psi);
723out:
724 mutex_unlock(&psi->read_mutex);
725
726 if (failed)
727 pr_warn("failed to create %d record(s) from '%s'\n",
728 failed, psi->name);
729 if (!stop_loop)
730 pr_err("looping? Too many records seen from '%s'\n",
731 psi->name);
732}
733
734static void pstore_dowork(struct work_struct *work)
735{
736 pstore_get_records(1);
737}
738
739static void pstore_timefunc(struct timer_list *unused)
740{
741 if (pstore_new_entry) {
742 pstore_new_entry = 0;
743 schedule_work(&pstore_work);
744 }
745
746 if (pstore_update_ms >= 0)
747 mod_timer(&pstore_timer,
748 jiffies + msecs_to_jiffies(pstore_update_ms));
749}
750
751void __init pstore_choose_compression(void)
752{
753 const struct pstore_zbackend *step;
754
755 if (!compress)
756 return;
757
758 for (step = zbackends; step->name; step++) {
759 if (!strcmp(compress, step->name)) {
760 zbackend = step;
761 pr_info("using %s compression\n", zbackend->name);
762 return;
763 }
764 }
765}
766
767module_param(compress, charp, 0444);
768MODULE_PARM_DESC(compress, "Pstore compression to use");
769
770module_param(backend, charp, 0444);
771MODULE_PARM_DESC(backend, "Pstore backend to use");