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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 is not 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 * pstore_lock just protects "psinfo" during
73 * calls to pstore_register()
74 */
75static DEFINE_SPINLOCK(pstore_lock);
76struct pstore_info *psinfo;
77
78static char *backend;
79static char *compress =
80#ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
81 CONFIG_PSTORE_COMPRESS_DEFAULT;
82#else
83 NULL;
84#endif
85
86/* Compression parameters */
87static struct crypto_comp *tfm;
88
89struct pstore_zbackend {
90 int (*zbufsize)(size_t size);
91 const char *name;
92};
93
94static char *big_oops_buf;
95static size_t big_oops_buf_sz;
96
97/* How much of the console log to snapshot */
98unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
99
100void pstore_set_kmsg_bytes(int bytes)
101{
102 kmsg_bytes = bytes;
103}
104
105/* Tag each group of saved records with a sequence number */
106static int oopscount;
107
108const char *pstore_type_to_name(enum pstore_type_id type)
109{
110 BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
111
112 if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
113 return "unknown";
114
115 return pstore_type_names[type];
116}
117EXPORT_SYMBOL_GPL(pstore_type_to_name);
118
119enum pstore_type_id pstore_name_to_type(const char *name)
120{
121 int i;
122
123 for (i = 0; i < PSTORE_TYPE_MAX; i++) {
124 if (!strcmp(pstore_type_names[i], name))
125 return i;
126 }
127
128 return PSTORE_TYPE_MAX;
129}
130EXPORT_SYMBOL_GPL(pstore_name_to_type);
131
132static const char *get_reason_str(enum kmsg_dump_reason reason)
133{
134 switch (reason) {
135 case KMSG_DUMP_PANIC:
136 return "Panic";
137 case KMSG_DUMP_OOPS:
138 return "Oops";
139 case KMSG_DUMP_EMERG:
140 return "Emergency";
141 case KMSG_DUMP_RESTART:
142 return "Restart";
143 case KMSG_DUMP_HALT:
144 return "Halt";
145 case KMSG_DUMP_POWEROFF:
146 return "Poweroff";
147 default:
148 return "Unknown";
149 }
150}
151
152/*
153 * Should pstore_dump() wait for a concurrent pstore_dump()? If
154 * not, the current pstore_dump() will report a failure to dump
155 * and return.
156 */
157static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
158{
159 /* In NMI path, pstore shouldn't block regardless of reason. */
160 if (in_nmi())
161 return true;
162
163 switch (reason) {
164 /* In panic case, other cpus are stopped by smp_send_stop(). */
165 case KMSG_DUMP_PANIC:
166 /* Emergency restart shouldn't be blocked. */
167 case KMSG_DUMP_EMERG:
168 return true;
169 default:
170 return false;
171 }
172}
173
174#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
175static int zbufsize_deflate(size_t size)
176{
177 size_t cmpr;
178
179 switch (size) {
180 /* buffer range for efivars */
181 case 1000 ... 2000:
182 cmpr = 56;
183 break;
184 case 2001 ... 3000:
185 cmpr = 54;
186 break;
187 case 3001 ... 3999:
188 cmpr = 52;
189 break;
190 /* buffer range for nvram, erst */
191 case 4000 ... 10000:
192 cmpr = 45;
193 break;
194 default:
195 cmpr = 60;
196 break;
197 }
198
199 return (size * 100) / cmpr;
200}
201#endif
202
203#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
204static int zbufsize_lzo(size_t size)
205{
206 return lzo1x_worst_compress(size);
207}
208#endif
209
210#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
211static int zbufsize_lz4(size_t size)
212{
213 return LZ4_compressBound(size);
214}
215#endif
216
217#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
218static int zbufsize_842(size_t size)
219{
220 return size;
221}
222#endif
223
224#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
225static int zbufsize_zstd(size_t size)
226{
227 return ZSTD_compressBound(size);
228}
229#endif
230
231static const struct pstore_zbackend *zbackend __ro_after_init;
232
233static const struct pstore_zbackend zbackends[] = {
234#if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
235 {
236 .zbufsize = zbufsize_deflate,
237 .name = "deflate",
238 },
239#endif
240#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
241 {
242 .zbufsize = zbufsize_lzo,
243 .name = "lzo",
244 },
245#endif
246#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
247 {
248 .zbufsize = zbufsize_lz4,
249 .name = "lz4",
250 },
251#endif
252#if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
253 {
254 .zbufsize = zbufsize_lz4,
255 .name = "lz4hc",
256 },
257#endif
258#if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
259 {
260 .zbufsize = zbufsize_842,
261 .name = "842",
262 },
263#endif
264#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
265 {
266 .zbufsize = zbufsize_zstd,
267 .name = "zstd",
268 },
269#endif
270 { }
271};
272
273static int pstore_compress(const void *in, void *out,
274 unsigned int inlen, unsigned int outlen)
275{
276 int ret;
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 unsigned long total = 0;
392 const char *why;
393 unsigned int part = 1;
394 int ret;
395
396 why = get_reason_str(reason);
397
398 if (down_trylock(&psinfo->buf_lock)) {
399 /* Failed to acquire lock: give up if we cannot wait. */
400 if (pstore_cannot_wait(reason)) {
401 pr_err("dump skipped in %s path: may corrupt error record\n",
402 in_nmi() ? "NMI" : why);
403 return;
404 }
405 if (down_interruptible(&psinfo->buf_lock)) {
406 pr_err("could not grab semaphore?!\n");
407 return;
408 }
409 }
410
411 oopscount++;
412 while (total < kmsg_bytes) {
413 char *dst;
414 size_t dst_size;
415 int header_size;
416 int zipped_len = -1;
417 size_t dump_size;
418 struct pstore_record record;
419
420 pstore_record_init(&record, psinfo);
421 record.type = PSTORE_TYPE_DMESG;
422 record.count = oopscount;
423 record.reason = reason;
424 record.part = part;
425 record.buf = psinfo->buf;
426
427 if (big_oops_buf) {
428 dst = big_oops_buf;
429 dst_size = big_oops_buf_sz;
430 } else {
431 dst = psinfo->buf;
432 dst_size = psinfo->bufsize;
433 }
434
435 /* Write dump header. */
436 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
437 oopscount, part);
438 dst_size -= header_size;
439
440 /* Write dump contents. */
441 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
442 dst_size, &dump_size))
443 break;
444
445 if (big_oops_buf) {
446 zipped_len = pstore_compress(dst, psinfo->buf,
447 header_size + dump_size,
448 psinfo->bufsize);
449
450 if (zipped_len > 0) {
451 record.compressed = true;
452 record.size = zipped_len;
453 } else {
454 record.size = copy_kmsg_to_buffer(header_size,
455 dump_size);
456 }
457 } else {
458 record.size = header_size + dump_size;
459 }
460
461 ret = psinfo->write(&record);
462 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
463 pstore_new_entry = 1;
464
465 total += record.size;
466 part++;
467 }
468
469 up(&psinfo->buf_lock);
470}
471
472static struct kmsg_dumper pstore_dumper = {
473 .dump = pstore_dump,
474};
475
476/*
477 * Register with kmsg_dump to save last part of console log on panic.
478 */
479static void pstore_register_kmsg(void)
480{
481 kmsg_dump_register(&pstore_dumper);
482}
483
484static void pstore_unregister_kmsg(void)
485{
486 kmsg_dump_unregister(&pstore_dumper);
487}
488
489#ifdef CONFIG_PSTORE_CONSOLE
490static void pstore_console_write(struct console *con, const char *s, unsigned c)
491{
492 struct pstore_record record;
493
494 if (!c)
495 return;
496
497 pstore_record_init(&record, psinfo);
498 record.type = PSTORE_TYPE_CONSOLE;
499
500 record.buf = (char *)s;
501 record.size = c;
502 psinfo->write(&record);
503}
504
505static struct console pstore_console = {
506 .name = "pstore",
507 .write = pstore_console_write,
508 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
509 .index = -1,
510};
511
512static void pstore_register_console(void)
513{
514 register_console(&pstore_console);
515}
516
517static void pstore_unregister_console(void)
518{
519 unregister_console(&pstore_console);
520}
521#else
522static void pstore_register_console(void) {}
523static void pstore_unregister_console(void) {}
524#endif
525
526static int pstore_write_user_compat(struct pstore_record *record,
527 const char __user *buf)
528{
529 int ret = 0;
530
531 if (record->buf)
532 return -EINVAL;
533
534 record->buf = memdup_user(buf, record->size);
535 if (IS_ERR(record->buf)) {
536 ret = PTR_ERR(record->buf);
537 goto out;
538 }
539
540 ret = record->psi->write(record);
541
542 kfree(record->buf);
543out:
544 record->buf = NULL;
545
546 return unlikely(ret < 0) ? ret : record->size;
547}
548
549/*
550 * platform specific persistent storage driver registers with
551 * us here. If pstore is already mounted, call the platform
552 * read function right away to populate the file system. If not
553 * then the pstore mount code will call us later to fill out
554 * the file system.
555 */
556int pstore_register(struct pstore_info *psi)
557{
558 struct module *owner = psi->owner;
559
560 if (backend && strcmp(backend, psi->name)) {
561 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
562 return -EPERM;
563 }
564
565 /* Sanity check flags. */
566 if (!psi->flags) {
567 pr_warn("backend '%s' must support at least one frontend\n",
568 psi->name);
569 return -EINVAL;
570 }
571
572 /* Check for required functions. */
573 if (!psi->read || !psi->write) {
574 pr_warn("backend '%s' must implement read() and write()\n",
575 psi->name);
576 return -EINVAL;
577 }
578
579 spin_lock(&pstore_lock);
580 if (psinfo) {
581 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
582 psinfo->name, psi->name);
583 spin_unlock(&pstore_lock);
584 return -EBUSY;
585 }
586
587 if (!psi->write_user)
588 psi->write_user = pstore_write_user_compat;
589 psinfo = psi;
590 mutex_init(&psinfo->read_mutex);
591 sema_init(&psinfo->buf_lock, 1);
592 spin_unlock(&pstore_lock);
593
594 if (owner && !try_module_get(owner)) {
595 psinfo = NULL;
596 return -EINVAL;
597 }
598
599 if (psi->flags & PSTORE_FLAGS_DMESG)
600 allocate_buf_for_compression();
601
602 if (pstore_is_mounted())
603 pstore_get_records(0);
604
605 if (psi->flags & PSTORE_FLAGS_DMESG)
606 pstore_register_kmsg();
607 if (psi->flags & PSTORE_FLAGS_CONSOLE)
608 pstore_register_console();
609 if (psi->flags & PSTORE_FLAGS_FTRACE)
610 pstore_register_ftrace();
611 if (psi->flags & PSTORE_FLAGS_PMSG)
612 pstore_register_pmsg();
613
614 /* Start watching for new records, if desired. */
615 if (pstore_update_ms >= 0) {
616 pstore_timer.expires = jiffies +
617 msecs_to_jiffies(pstore_update_ms);
618 add_timer(&pstore_timer);
619 }
620
621 /*
622 * Update the module parameter backend, so it is visible
623 * through /sys/module/pstore/parameters/backend
624 */
625 backend = psi->name;
626
627 pr_info("Registered %s as persistent store backend\n", psi->name);
628
629 module_put(owner);
630
631 return 0;
632}
633EXPORT_SYMBOL_GPL(pstore_register);
634
635void pstore_unregister(struct pstore_info *psi)
636{
637 /* Stop timer and make sure all work has finished. */
638 pstore_update_ms = -1;
639 del_timer_sync(&pstore_timer);
640 flush_work(&pstore_work);
641
642 if (psi->flags & PSTORE_FLAGS_PMSG)
643 pstore_unregister_pmsg();
644 if (psi->flags & PSTORE_FLAGS_FTRACE)
645 pstore_unregister_ftrace();
646 if (psi->flags & PSTORE_FLAGS_CONSOLE)
647 pstore_unregister_console();
648 if (psi->flags & PSTORE_FLAGS_DMESG)
649 pstore_unregister_kmsg();
650
651 free_buf_for_compression();
652
653 psinfo = NULL;
654 backend = NULL;
655}
656EXPORT_SYMBOL_GPL(pstore_unregister);
657
658static void decompress_record(struct pstore_record *record)
659{
660 int ret;
661 int unzipped_len;
662 char *unzipped, *workspace;
663
664 if (!record->compressed)
665 return;
666
667 /* Only PSTORE_TYPE_DMESG support compression. */
668 if (record->type != PSTORE_TYPE_DMESG) {
669 pr_warn("ignored compressed record type %d\n", record->type);
670 return;
671 }
672
673 /* Missing compression buffer means compression was not initialized. */
674 if (!big_oops_buf) {
675 pr_warn("no decompression method initialized!\n");
676 return;
677 }
678
679 /* Allocate enough space to hold max decompression and ECC. */
680 unzipped_len = big_oops_buf_sz;
681 workspace = kmalloc(unzipped_len + record->ecc_notice_size,
682 GFP_KERNEL);
683 if (!workspace)
684 return;
685
686 /* After decompression "unzipped_len" is almost certainly smaller. */
687 ret = crypto_comp_decompress(tfm, record->buf, record->size,
688 workspace, &unzipped_len);
689 if (ret) {
690 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
691 kfree(workspace);
692 return;
693 }
694
695 /* Append ECC notice to decompressed buffer. */
696 memcpy(workspace + unzipped_len, record->buf + record->size,
697 record->ecc_notice_size);
698
699 /* Copy decompressed contents into an minimum-sized allocation. */
700 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
701 GFP_KERNEL);
702 kfree(workspace);
703 if (!unzipped)
704 return;
705
706 /* Swap out compressed contents with decompressed contents. */
707 kfree(record->buf);
708 record->buf = unzipped;
709 record->size = unzipped_len;
710 record->compressed = false;
711}
712
713/*
714 * Read all the records from one persistent store backend. Create
715 * files in our filesystem. Don't warn about -EEXIST errors
716 * when we are re-scanning the backing store looking to add new
717 * error records.
718 */
719void pstore_get_backend_records(struct pstore_info *psi,
720 struct dentry *root, int quiet)
721{
722 int failed = 0;
723 unsigned int stop_loop = 65536;
724
725 if (!psi || !root)
726 return;
727
728 mutex_lock(&psi->read_mutex);
729 if (psi->open && psi->open(psi))
730 goto out;
731
732 /*
733 * Backend callback read() allocates record.buf. decompress_record()
734 * may reallocate record.buf. On success, pstore_mkfile() will keep
735 * the record.buf, so free it only on failure.
736 */
737 for (; stop_loop; stop_loop--) {
738 struct pstore_record *record;
739 int rc;
740
741 record = kzalloc(sizeof(*record), GFP_KERNEL);
742 if (!record) {
743 pr_err("out of memory creating record\n");
744 break;
745 }
746 pstore_record_init(record, psi);
747
748 record->size = psi->read(record);
749
750 /* No more records left in backend? */
751 if (record->size <= 0) {
752 kfree(record);
753 break;
754 }
755
756 decompress_record(record);
757 rc = pstore_mkfile(root, record);
758 if (rc) {
759 /* pstore_mkfile() did not take record, so free it. */
760 kfree(record->buf);
761 kfree(record);
762 if (rc != -EEXIST || !quiet)
763 failed++;
764 }
765 }
766 if (psi->close)
767 psi->close(psi);
768out:
769 mutex_unlock(&psi->read_mutex);
770
771 if (failed)
772 pr_warn("failed to create %d record(s) from '%s'\n",
773 failed, psi->name);
774 if (!stop_loop)
775 pr_err("looping? Too many records seen from '%s'\n",
776 psi->name);
777}
778
779static void pstore_dowork(struct work_struct *work)
780{
781 pstore_get_records(1);
782}
783
784static void pstore_timefunc(struct timer_list *unused)
785{
786 if (pstore_new_entry) {
787 pstore_new_entry = 0;
788 schedule_work(&pstore_work);
789 }
790
791 if (pstore_update_ms >= 0)
792 mod_timer(&pstore_timer,
793 jiffies + msecs_to_jiffies(pstore_update_ms));
794}
795
796void __init pstore_choose_compression(void)
797{
798 const struct pstore_zbackend *step;
799
800 if (!compress)
801 return;
802
803 for (step = zbackends; step->name; step++) {
804 if (!strcmp(compress, step->name)) {
805 zbackend = step;
806 return;
807 }
808 }
809}
810
811static int __init pstore_init(void)
812{
813 int ret;
814
815 pstore_choose_compression();
816
817 /*
818 * Check if any pstore backends registered earlier but did not
819 * initialize compression because crypto was not ready. If so,
820 * initialize compression now.
821 */
822 allocate_buf_for_compression();
823
824 ret = pstore_init_fs();
825 if (ret)
826 return ret;
827
828 return 0;
829}
830late_initcall(pstore_init);
831
832static void __exit pstore_exit(void)
833{
834 pstore_exit_fs();
835}
836module_exit(pstore_exit)
837
838module_param(compress, charp, 0444);
839MODULE_PARM_DESC(compress, "Pstore compression to use");
840
841module_param(backend, charp, 0444);
842MODULE_PARM_DESC(backend, "Pstore backend to use");
843
844MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
845MODULE_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#include <linux/atomic.h>
22#include <linux/types.h>
23#include <linux/errno.h>
24#include <linux/init.h>
25#include <linux/kmsg_dump.h>
26#include <linux/console.h>
27#include <linux/module.h>
28#include <linux/pstore.h>
29#include <linux/zlib.h>
30#include <linux/string.h>
31#include <linux/timer.h>
32#include <linux/slab.h>
33#include <linux/uaccess.h>
34#include <linux/hardirq.h>
35#include <linux/jiffies.h>
36#include <linux/workqueue.h>
37
38#include "internal.h"
39
40/*
41 * We defer making "oops" entries appear in pstore - see
42 * whether the system is actually still running well enough
43 * to let someone see the entry
44 */
45static int pstore_update_ms = -1;
46module_param_named(update_ms, pstore_update_ms, int, 0600);
47MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
48 "(default is -1, which means runtime updates are disabled; "
49 "enabling this option is not safe, it may lead to further "
50 "corruption on Oopses)");
51
52static int pstore_new_entry;
53
54static void pstore_timefunc(unsigned long);
55static DEFINE_TIMER(pstore_timer, pstore_timefunc, 0, 0);
56
57static void pstore_dowork(struct work_struct *);
58static DECLARE_WORK(pstore_work, pstore_dowork);
59
60/*
61 * pstore_lock just protects "psinfo" during
62 * calls to pstore_register()
63 */
64static DEFINE_SPINLOCK(pstore_lock);
65struct pstore_info *psinfo;
66
67static char *backend;
68
69/* Compression parameters */
70#define COMPR_LEVEL 6
71#define WINDOW_BITS 12
72#define MEM_LEVEL 4
73static struct z_stream_s stream;
74
75static char *big_oops_buf;
76static size_t big_oops_buf_sz;
77
78/* How much of the console log to snapshot */
79static unsigned long kmsg_bytes = 10240;
80
81void pstore_set_kmsg_bytes(int bytes)
82{
83 kmsg_bytes = bytes;
84}
85
86/* Tag each group of saved records with a sequence number */
87static int oopscount;
88
89static const char *get_reason_str(enum kmsg_dump_reason reason)
90{
91 switch (reason) {
92 case KMSG_DUMP_PANIC:
93 return "Panic";
94 case KMSG_DUMP_OOPS:
95 return "Oops";
96 case KMSG_DUMP_EMERG:
97 return "Emergency";
98 case KMSG_DUMP_RESTART:
99 return "Restart";
100 case KMSG_DUMP_HALT:
101 return "Halt";
102 case KMSG_DUMP_POWEROFF:
103 return "Poweroff";
104 default:
105 return "Unknown";
106 }
107}
108
109bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
110{
111 /*
112 * In case of NMI path, pstore shouldn't be blocked
113 * regardless of reason.
114 */
115 if (in_nmi())
116 return true;
117
118 switch (reason) {
119 /* In panic case, other cpus are stopped by smp_send_stop(). */
120 case KMSG_DUMP_PANIC:
121 /* Emergency restart shouldn't be blocked by spin lock. */
122 case KMSG_DUMP_EMERG:
123 return true;
124 default:
125 return false;
126 }
127}
128EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
129
130/* Derived from logfs_compress() */
131static int pstore_compress(const void *in, void *out, size_t inlen,
132 size_t outlen)
133{
134 int err, ret;
135
136 ret = -EIO;
137 err = zlib_deflateInit2(&stream, COMPR_LEVEL, Z_DEFLATED, WINDOW_BITS,
138 MEM_LEVEL, Z_DEFAULT_STRATEGY);
139 if (err != Z_OK)
140 goto error;
141
142 stream.next_in = in;
143 stream.avail_in = inlen;
144 stream.total_in = 0;
145 stream.next_out = out;
146 stream.avail_out = outlen;
147 stream.total_out = 0;
148
149 err = zlib_deflate(&stream, Z_FINISH);
150 if (err != Z_STREAM_END)
151 goto error;
152
153 err = zlib_deflateEnd(&stream);
154 if (err != Z_OK)
155 goto error;
156
157 if (stream.total_out >= stream.total_in)
158 goto error;
159
160 ret = stream.total_out;
161error:
162 return ret;
163}
164
165/* Derived from logfs_uncompress */
166static int pstore_decompress(void *in, void *out, size_t inlen, size_t outlen)
167{
168 int err, ret;
169
170 ret = -EIO;
171 err = zlib_inflateInit2(&stream, WINDOW_BITS);
172 if (err != Z_OK)
173 goto error;
174
175 stream.next_in = in;
176 stream.avail_in = inlen;
177 stream.total_in = 0;
178 stream.next_out = out;
179 stream.avail_out = outlen;
180 stream.total_out = 0;
181
182 err = zlib_inflate(&stream, Z_FINISH);
183 if (err != Z_STREAM_END)
184 goto error;
185
186 err = zlib_inflateEnd(&stream);
187 if (err != Z_OK)
188 goto error;
189
190 ret = stream.total_out;
191error:
192 return ret;
193}
194
195static void allocate_buf_for_compression(void)
196{
197 size_t size;
198 size_t cmpr;
199
200 switch (psinfo->bufsize) {
201 /* buffer range for efivars */
202 case 1000 ... 2000:
203 cmpr = 56;
204 break;
205 case 2001 ... 3000:
206 cmpr = 54;
207 break;
208 case 3001 ... 3999:
209 cmpr = 52;
210 break;
211 /* buffer range for nvram, erst */
212 case 4000 ... 10000:
213 cmpr = 45;
214 break;
215 default:
216 cmpr = 60;
217 break;
218 }
219
220 big_oops_buf_sz = (psinfo->bufsize * 100) / cmpr;
221 big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
222 if (big_oops_buf) {
223 size = max(zlib_deflate_workspacesize(WINDOW_BITS, MEM_LEVEL),
224 zlib_inflate_workspacesize());
225 stream.workspace = kmalloc(size, GFP_KERNEL);
226 if (!stream.workspace) {
227 pr_err("pstore: No memory for compression workspace; "
228 "skipping compression\n");
229 kfree(big_oops_buf);
230 big_oops_buf = NULL;
231 }
232 } else {
233 pr_err("No memory for uncompressed data; "
234 "skipping compression\n");
235 stream.workspace = NULL;
236 }
237
238}
239
240/*
241 * Called when compression fails, since the printk buffer
242 * would be fetched for compression calling it again when
243 * compression fails would have moved the iterator of
244 * printk buffer which results in fetching old contents.
245 * Copy the recent messages from big_oops_buf to psinfo->buf
246 */
247static size_t copy_kmsg_to_buffer(int hsize, size_t len)
248{
249 size_t total_len;
250 size_t diff;
251
252 total_len = hsize + len;
253
254 if (total_len > psinfo->bufsize) {
255 diff = total_len - psinfo->bufsize + hsize;
256 memcpy(psinfo->buf, big_oops_buf, hsize);
257 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
258 psinfo->bufsize - hsize);
259 total_len = psinfo->bufsize;
260 } else
261 memcpy(psinfo->buf, big_oops_buf, total_len);
262
263 return total_len;
264}
265
266/*
267 * callback from kmsg_dump. (s2,l2) has the most recently
268 * written bytes, older bytes are in (s1,l1). Save as much
269 * as we can from the end of the buffer.
270 */
271static void pstore_dump(struct kmsg_dumper *dumper,
272 enum kmsg_dump_reason reason)
273{
274 unsigned long total = 0;
275 const char *why;
276 u64 id;
277 unsigned int part = 1;
278 unsigned long flags = 0;
279 int is_locked = 0;
280 int ret;
281
282 why = get_reason_str(reason);
283
284 if (pstore_cannot_block_path(reason)) {
285 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
286 if (!is_locked) {
287 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
288 , in_nmi() ? "NMI" : why);
289 }
290 } else
291 spin_lock_irqsave(&psinfo->buf_lock, flags);
292 oopscount++;
293 while (total < kmsg_bytes) {
294 char *dst;
295 unsigned long size;
296 int hsize;
297 int zipped_len = -1;
298 size_t len;
299 bool compressed;
300 size_t total_len;
301
302 if (big_oops_buf) {
303 dst = big_oops_buf;
304 hsize = sprintf(dst, "%s#%d Part%d\n", why,
305 oopscount, part);
306 size = big_oops_buf_sz - hsize;
307
308 if (!kmsg_dump_get_buffer(dumper, true, dst + hsize,
309 size, &len))
310 break;
311
312 zipped_len = pstore_compress(dst, psinfo->buf,
313 hsize + len, psinfo->bufsize);
314
315 if (zipped_len > 0) {
316 compressed = true;
317 total_len = zipped_len;
318 } else {
319 compressed = false;
320 total_len = copy_kmsg_to_buffer(hsize, len);
321 }
322 } else {
323 dst = psinfo->buf;
324 hsize = sprintf(dst, "%s#%d Part%d\n", why, oopscount,
325 part);
326 size = psinfo->bufsize - hsize;
327 dst += hsize;
328
329 if (!kmsg_dump_get_buffer(dumper, true, dst,
330 size, &len))
331 break;
332
333 compressed = false;
334 total_len = hsize + len;
335 }
336
337 ret = psinfo->write(PSTORE_TYPE_DMESG, reason, &id, part,
338 oopscount, compressed, total_len, psinfo);
339 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
340 pstore_new_entry = 1;
341
342 total += total_len;
343 part++;
344 }
345 if (pstore_cannot_block_path(reason)) {
346 if (is_locked)
347 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
348 } else
349 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
350}
351
352static struct kmsg_dumper pstore_dumper = {
353 .dump = pstore_dump,
354};
355
356#ifdef CONFIG_PSTORE_CONSOLE
357static void pstore_console_write(struct console *con, const char *s, unsigned c)
358{
359 const char *e = s + c;
360
361 while (s < e) {
362 unsigned long flags;
363 u64 id;
364
365 if (c > psinfo->bufsize)
366 c = psinfo->bufsize;
367
368 if (oops_in_progress) {
369 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
370 break;
371 } else {
372 spin_lock_irqsave(&psinfo->buf_lock, flags);
373 }
374 memcpy(psinfo->buf, s, c);
375 psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
376 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
377 s += c;
378 c = e - s;
379 }
380}
381
382static struct console pstore_console = {
383 .name = "pstore",
384 .write = pstore_console_write,
385 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
386 .index = -1,
387};
388
389static void pstore_register_console(void)
390{
391 register_console(&pstore_console);
392}
393#else
394static void pstore_register_console(void) {}
395#endif
396
397static int pstore_write_compat(enum pstore_type_id type,
398 enum kmsg_dump_reason reason,
399 u64 *id, unsigned int part, int count,
400 bool compressed, size_t size,
401 struct pstore_info *psi)
402{
403 return psi->write_buf(type, reason, id, part, psinfo->buf, compressed,
404 size, psi);
405}
406
407/*
408 * platform specific persistent storage driver registers with
409 * us here. If pstore is already mounted, call the platform
410 * read function right away to populate the file system. If not
411 * then the pstore mount code will call us later to fill out
412 * the file system.
413 *
414 * Register with kmsg_dump to save last part of console log on panic.
415 */
416int pstore_register(struct pstore_info *psi)
417{
418 struct module *owner = psi->owner;
419
420 if (backend && strcmp(backend, psi->name))
421 return -EPERM;
422
423 spin_lock(&pstore_lock);
424 if (psinfo) {
425 spin_unlock(&pstore_lock);
426 return -EBUSY;
427 }
428
429 if (!psi->write)
430 psi->write = pstore_write_compat;
431 psinfo = psi;
432 mutex_init(&psinfo->read_mutex);
433 spin_unlock(&pstore_lock);
434
435 if (owner && !try_module_get(owner)) {
436 psinfo = NULL;
437 return -EINVAL;
438 }
439
440 allocate_buf_for_compression();
441
442 if (pstore_is_mounted())
443 pstore_get_records(0);
444
445 kmsg_dump_register(&pstore_dumper);
446
447 if ((psi->flags & PSTORE_FLAGS_FRAGILE) == 0) {
448 pstore_register_console();
449 pstore_register_ftrace();
450 }
451
452 if (pstore_update_ms >= 0) {
453 pstore_timer.expires = jiffies +
454 msecs_to_jiffies(pstore_update_ms);
455 add_timer(&pstore_timer);
456 }
457
458 pr_info("pstore: Registered %s as persistent store backend\n",
459 psi->name);
460
461 return 0;
462}
463EXPORT_SYMBOL_GPL(pstore_register);
464
465/*
466 * Read all the records from the persistent store. Create
467 * files in our filesystem. Don't warn about -EEXIST errors
468 * when we are re-scanning the backing store looking to add new
469 * error records.
470 */
471void pstore_get_records(int quiet)
472{
473 struct pstore_info *psi = psinfo;
474 char *buf = NULL;
475 ssize_t size;
476 u64 id;
477 int count;
478 enum pstore_type_id type;
479 struct timespec time;
480 int failed = 0, rc;
481 bool compressed;
482 int unzipped_len = -1;
483
484 if (!psi)
485 return;
486
487 mutex_lock(&psi->read_mutex);
488 if (psi->open && psi->open(psi))
489 goto out;
490
491 while ((size = psi->read(&id, &type, &count, &time, &buf, &compressed,
492 psi)) > 0) {
493 if (compressed && (type == PSTORE_TYPE_DMESG)) {
494 if (big_oops_buf)
495 unzipped_len = pstore_decompress(buf,
496 big_oops_buf, size,
497 big_oops_buf_sz);
498
499 if (unzipped_len > 0) {
500 kfree(buf);
501 buf = big_oops_buf;
502 size = unzipped_len;
503 compressed = false;
504 } else {
505 pr_err("pstore: decompression failed;"
506 "returned %d\n", unzipped_len);
507 compressed = true;
508 }
509 }
510 rc = pstore_mkfile(type, psi->name, id, count, buf,
511 compressed, (size_t)size, time, psi);
512 if (unzipped_len < 0) {
513 /* Free buffer other than big oops */
514 kfree(buf);
515 buf = NULL;
516 } else
517 unzipped_len = -1;
518 if (rc && (rc != -EEXIST || !quiet))
519 failed++;
520 }
521 if (psi->close)
522 psi->close(psi);
523out:
524 mutex_unlock(&psi->read_mutex);
525
526 if (failed)
527 printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
528 failed, psi->name);
529}
530
531static void pstore_dowork(struct work_struct *work)
532{
533 pstore_get_records(1);
534}
535
536static void pstore_timefunc(unsigned long dummy)
537{
538 if (pstore_new_entry) {
539 pstore_new_entry = 0;
540 schedule_work(&pstore_work);
541 }
542
543 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
544}
545
546module_param(backend, charp, 0444);
547MODULE_PARM_DESC(backend, "Pstore backend to use");