2 * Persistent Storage - platform driver interface parts.
4 * Copyright (C) 2007-2008 Google, Inc.
5 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
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.
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.
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
21 #define pr_fmt(fmt) "pstore: " fmt
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>
34 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
35 #include <linux/lz4.h>
37 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
38 #include <linux/zstd.h>
40 #include <linux/crypto.h>
41 #include <linux/string.h>
42 #include <linux/timer.h>
43 #include <linux/slab.h>
44 #include <linux/uaccess.h>
45 #include <linux/jiffies.h>
46 #include <linux/workqueue.h>
51 * We defer making "oops" entries appear in pstore - see
52 * whether the system is actually still running well enough
53 * to let someone see the entry
55 static int pstore_update_ms = -1;
56 module_param_named(update_ms, pstore_update_ms, int, 0600);
57 MODULE_PARM_DESC(update_ms, "milliseconds before pstore updates its content "
58 "(default is -1, which means runtime updates are disabled; "
59 "enabling this option is not safe, it may lead to further "
60 "corruption on Oopses)");
62 static int pstore_new_entry;
64 static void pstore_timefunc(struct timer_list *);
65 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
67 static void pstore_dowork(struct work_struct *);
68 static DECLARE_WORK(pstore_work, pstore_dowork);
71 * pstore_lock just protects "psinfo" during
72 * calls to pstore_register()
74 static DEFINE_SPINLOCK(pstore_lock);
75 struct pstore_info *psinfo;
78 static char *compress =
79 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
80 CONFIG_PSTORE_COMPRESS_DEFAULT;
85 /* Compression parameters */
86 static struct crypto_comp *tfm;
88 struct pstore_zbackend {
89 int (*zbufsize)(size_t size);
93 static char *big_oops_buf;
94 static size_t big_oops_buf_sz;
96 /* How much of the console log to snapshot */
97 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
99 void pstore_set_kmsg_bytes(int bytes)
104 /* Tag each group of saved records with a sequence number */
105 static int oopscount;
107 static const char *get_reason_str(enum kmsg_dump_reason reason)
110 case KMSG_DUMP_PANIC:
114 case KMSG_DUMP_EMERG:
116 case KMSG_DUMP_RESTART:
120 case KMSG_DUMP_POWEROFF:
127 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
130 * In case of NMI path, pstore shouldn't be blocked
131 * regardless of reason.
137 /* In panic case, other cpus are stopped by smp_send_stop(). */
138 case KMSG_DUMP_PANIC:
139 /* Emergency restart shouldn't be blocked by spin lock. */
140 case KMSG_DUMP_EMERG:
146 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
148 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
149 static int zbufsize_deflate(size_t size)
154 /* buffer range for efivars */
164 /* buffer range for nvram, erst */
173 return (size * 100) / cmpr;
177 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
178 static int zbufsize_lzo(size_t size)
180 return lzo1x_worst_compress(size);
184 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
185 static int zbufsize_lz4(size_t size)
187 return LZ4_compressBound(size);
191 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
192 static int zbufsize_842(size_t size)
198 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
199 static int zbufsize_zstd(size_t size)
201 return ZSTD_compressBound(size);
205 static const struct pstore_zbackend *zbackend __ro_after_init;
207 static const struct pstore_zbackend zbackends[] = {
208 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
210 .zbufsize = zbufsize_deflate,
214 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
216 .zbufsize = zbufsize_lzo,
220 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
222 .zbufsize = zbufsize_lz4,
226 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
228 .zbufsize = zbufsize_lz4,
232 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
234 .zbufsize = zbufsize_842,
238 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
240 .zbufsize = zbufsize_zstd,
247 static int pstore_compress(const void *in, void *out,
248 unsigned int inlen, unsigned int outlen)
252 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
254 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
261 static int pstore_decompress(void *in, void *out,
262 unsigned int inlen, unsigned int outlen)
266 ret = crypto_comp_decompress(tfm, in, inlen, out, &outlen);
268 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
275 static void allocate_buf_for_compression(void)
277 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
280 if (!crypto_has_comp(zbackend->name, 0, 0)) {
281 pr_err("No %s compression\n", zbackend->name);
285 big_oops_buf_sz = zbackend->zbufsize(psinfo->bufsize);
286 if (big_oops_buf_sz <= 0)
289 big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
291 pr_err("allocate compression buffer error!\n");
295 tfm = crypto_alloc_comp(zbackend->name, 0, 0);
296 if (IS_ERR_OR_NULL(tfm)) {
299 pr_err("crypto_alloc_comp() failed!\n");
304 static void free_buf_for_compression(void)
306 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && !IS_ERR_OR_NULL(tfm))
307 crypto_free_comp(tfm);
314 * Called when compression fails, since the printk buffer
315 * would be fetched for compression calling it again when
316 * compression fails would have moved the iterator of
317 * printk buffer which results in fetching old contents.
318 * Copy the recent messages from big_oops_buf to psinfo->buf
320 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
325 total_len = hsize + len;
327 if (total_len > psinfo->bufsize) {
328 diff = total_len - psinfo->bufsize + hsize;
329 memcpy(psinfo->buf, big_oops_buf, hsize);
330 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
331 psinfo->bufsize - hsize);
332 total_len = psinfo->bufsize;
334 memcpy(psinfo->buf, big_oops_buf, total_len);
339 void pstore_record_init(struct pstore_record *record,
340 struct pstore_info *psinfo)
342 memset(record, 0, sizeof(*record));
344 record->psi = psinfo;
346 /* Report zeroed timestamp if called before timekeeping has resumed. */
347 record->time = ns_to_timespec64(ktime_get_real_fast_ns());
351 * callback from kmsg_dump. (s2,l2) has the most recently
352 * written bytes, older bytes are in (s1,l1). Save as much
353 * as we can from the end of the buffer.
355 static void pstore_dump(struct kmsg_dumper *dumper,
356 enum kmsg_dump_reason reason)
358 unsigned long total = 0;
360 unsigned int part = 1;
361 unsigned long flags = 0;
365 why = get_reason_str(reason);
367 if (pstore_cannot_block_path(reason)) {
368 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
370 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
371 , in_nmi() ? "NMI" : why);
375 spin_lock_irqsave(&psinfo->buf_lock, flags);
379 while (total < kmsg_bytes) {
385 struct pstore_record record;
387 pstore_record_init(&record, psinfo);
388 record.type = PSTORE_TYPE_DMESG;
389 record.count = oopscount;
390 record.reason = reason;
392 record.buf = psinfo->buf;
394 if (big_oops_buf && is_locked) {
396 dst_size = big_oops_buf_sz;
399 dst_size = psinfo->bufsize;
402 /* Write dump header. */
403 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
405 dst_size -= header_size;
407 /* Write dump contents. */
408 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
409 dst_size, &dump_size))
412 if (big_oops_buf && is_locked) {
413 zipped_len = pstore_compress(dst, psinfo->buf,
414 header_size + dump_size,
417 if (zipped_len > 0) {
418 record.compressed = true;
419 record.size = zipped_len;
421 record.size = copy_kmsg_to_buffer(header_size,
425 record.size = header_size + dump_size;
428 ret = psinfo->write(&record);
429 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
430 pstore_new_entry = 1;
432 total += record.size;
436 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
439 static struct kmsg_dumper pstore_dumper = {
444 * Register with kmsg_dump to save last part of console log on panic.
446 static void pstore_register_kmsg(void)
448 kmsg_dump_register(&pstore_dumper);
451 static void pstore_unregister_kmsg(void)
453 kmsg_dump_unregister(&pstore_dumper);
456 #ifdef CONFIG_PSTORE_CONSOLE
457 static void pstore_console_write(struct console *con, const char *s, unsigned c)
459 const char *e = s + c;
462 struct pstore_record record;
465 pstore_record_init(&record, psinfo);
466 record.type = PSTORE_TYPE_CONSOLE;
468 if (c > psinfo->bufsize)
471 if (oops_in_progress) {
472 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
475 spin_lock_irqsave(&psinfo->buf_lock, flags);
477 record.buf = (char *)s;
479 psinfo->write(&record);
480 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
486 static struct console pstore_console = {
488 .write = pstore_console_write,
489 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
493 static void pstore_register_console(void)
495 register_console(&pstore_console);
498 static void pstore_unregister_console(void)
500 unregister_console(&pstore_console);
503 static void pstore_register_console(void) {}
504 static void pstore_unregister_console(void) {}
507 static int pstore_write_user_compat(struct pstore_record *record,
508 const char __user *buf)
515 record->buf = memdup_user(buf, record->size);
516 if (IS_ERR(record->buf)) {
517 ret = PTR_ERR(record->buf);
521 ret = record->psi->write(record);
527 return unlikely(ret < 0) ? ret : record->size;
531 * platform specific persistent storage driver registers with
532 * us here. If pstore is already mounted, call the platform
533 * read function right away to populate the file system. If not
534 * then the pstore mount code will call us later to fill out
537 int pstore_register(struct pstore_info *psi)
539 struct module *owner = psi->owner;
541 if (backend && strcmp(backend, psi->name)) {
542 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
546 /* Sanity check flags. */
548 pr_warn("backend '%s' must support at least one frontend\n",
553 /* Check for required functions. */
554 if (!psi->read || !psi->write) {
555 pr_warn("backend '%s' must implement read() and write()\n",
560 spin_lock(&pstore_lock);
562 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
563 psinfo->name, psi->name);
564 spin_unlock(&pstore_lock);
568 if (!psi->write_user)
569 psi->write_user = pstore_write_user_compat;
571 mutex_init(&psinfo->read_mutex);
572 spin_unlock(&pstore_lock);
574 if (owner && !try_module_get(owner)) {
579 allocate_buf_for_compression();
581 if (pstore_is_mounted())
582 pstore_get_records(0);
584 if (psi->flags & PSTORE_FLAGS_DMESG)
585 pstore_register_kmsg();
586 if (psi->flags & PSTORE_FLAGS_CONSOLE)
587 pstore_register_console();
588 if (psi->flags & PSTORE_FLAGS_FTRACE)
589 pstore_register_ftrace();
590 if (psi->flags & PSTORE_FLAGS_PMSG)
591 pstore_register_pmsg();
593 /* Start watching for new records, if desired. */
594 if (pstore_update_ms >= 0) {
595 pstore_timer.expires = jiffies +
596 msecs_to_jiffies(pstore_update_ms);
597 add_timer(&pstore_timer);
601 * Update the module parameter backend, so it is visible
602 * through /sys/module/pstore/parameters/backend
606 pr_info("Registered %s as persistent store backend\n", psi->name);
612 EXPORT_SYMBOL_GPL(pstore_register);
614 void pstore_unregister(struct pstore_info *psi)
616 /* Stop timer and make sure all work has finished. */
617 pstore_update_ms = -1;
618 del_timer_sync(&pstore_timer);
619 flush_work(&pstore_work);
621 if (psi->flags & PSTORE_FLAGS_PMSG)
622 pstore_unregister_pmsg();
623 if (psi->flags & PSTORE_FLAGS_FTRACE)
624 pstore_unregister_ftrace();
625 if (psi->flags & PSTORE_FLAGS_CONSOLE)
626 pstore_unregister_console();
627 if (psi->flags & PSTORE_FLAGS_DMESG)
628 pstore_unregister_kmsg();
630 free_buf_for_compression();
635 EXPORT_SYMBOL_GPL(pstore_unregister);
637 static void decompress_record(struct pstore_record *record)
642 if (!record->compressed)
645 /* Only PSTORE_TYPE_DMESG support compression. */
646 if (record->type != PSTORE_TYPE_DMESG) {
647 pr_warn("ignored compressed record type %d\n", record->type);
651 /* No compression method has created the common buffer. */
653 pr_warn("no decompression buffer allocated\n");
657 unzipped_len = pstore_decompress(record->buf, big_oops_buf,
658 record->size, big_oops_buf_sz);
659 if (unzipped_len <= 0) {
660 pr_err("decompression failed: %d\n", unzipped_len);
664 /* Build new buffer for decompressed contents. */
665 decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
668 pr_err("decompression ran out of memory\n");
671 memcpy(decompressed, big_oops_buf, unzipped_len);
673 /* Append ECC notice to decompressed buffer. */
674 memcpy(decompressed + unzipped_len, record->buf + record->size,
675 record->ecc_notice_size);
677 /* Swap out compresed contents with decompressed contents. */
679 record->buf = decompressed;
680 record->size = unzipped_len;
681 record->compressed = false;
685 * Read all the records from one persistent store backend. Create
686 * files in our filesystem. Don't warn about -EEXIST errors
687 * when we are re-scanning the backing store looking to add new
690 void pstore_get_backend_records(struct pstore_info *psi,
691 struct dentry *root, int quiet)
694 unsigned int stop_loop = 65536;
699 mutex_lock(&psi->read_mutex);
700 if (psi->open && psi->open(psi))
704 * Backend callback read() allocates record.buf. decompress_record()
705 * may reallocate record.buf. On success, pstore_mkfile() will keep
706 * the record.buf, so free it only on failure.
708 for (; stop_loop; stop_loop--) {
709 struct pstore_record *record;
712 record = kzalloc(sizeof(*record), GFP_KERNEL);
714 pr_err("out of memory creating record\n");
717 pstore_record_init(record, psi);
719 record->size = psi->read(record);
721 /* No more records left in backend? */
722 if (record->size <= 0) {
727 decompress_record(record);
728 rc = pstore_mkfile(root, record);
730 /* pstore_mkfile() did not take record, so free it. */
733 if (rc != -EEXIST || !quiet)
740 mutex_unlock(&psi->read_mutex);
743 pr_warn("failed to create %d record(s) from '%s'\n",
746 pr_err("looping? Too many records seen from '%s'\n",
750 static void pstore_dowork(struct work_struct *work)
752 pstore_get_records(1);
755 static void pstore_timefunc(struct timer_list *unused)
757 if (pstore_new_entry) {
758 pstore_new_entry = 0;
759 schedule_work(&pstore_work);
762 if (pstore_update_ms >= 0)
763 mod_timer(&pstore_timer,
764 jiffies + msecs_to_jiffies(pstore_update_ms));
767 void __init pstore_choose_compression(void)
769 const struct pstore_zbackend *step;
774 for (step = zbackends; step->name; step++) {
775 if (!strcmp(compress, step->name)) {
777 pr_info("using %s compression\n", zbackend->name);
783 module_param(compress, charp, 0444);
784 MODULE_PARM_DESC(compress, "Pstore compression to use");
786 module_param(backend, charp, 0444);
787 MODULE_PARM_DESC(backend, "Pstore backend to use");