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 #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>
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
52 static int pstore_update_ms = -1;
53 module_param_named(update_ms, pstore_update_ms, int, 0600);
54 MODULE_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)");
59 static int pstore_new_entry;
61 static void pstore_timefunc(struct timer_list *);
62 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
64 static void pstore_dowork(struct work_struct *);
65 static DECLARE_WORK(pstore_work, pstore_dowork);
68 * pstore_lock just protects "psinfo" during
69 * calls to pstore_register()
71 static DEFINE_SPINLOCK(pstore_lock);
72 struct pstore_info *psinfo;
75 static char *compress =
76 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
77 CONFIG_PSTORE_COMPRESS_DEFAULT;
82 /* Compression parameters */
83 static struct crypto_comp *tfm;
85 struct pstore_zbackend {
86 int (*zbufsize)(size_t size);
90 static char *big_oops_buf;
91 static size_t big_oops_buf_sz;
93 /* How much of the console log to snapshot */
94 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
96 void pstore_set_kmsg_bytes(int bytes)
101 /* Tag each group of saved records with a sequence number */
102 static int oopscount;
104 static const char *get_reason_str(enum kmsg_dump_reason reason)
107 case KMSG_DUMP_PANIC:
111 case KMSG_DUMP_EMERG:
113 case KMSG_DUMP_RESTART:
117 case KMSG_DUMP_POWEROFF:
124 bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
127 * In case of NMI path, pstore shouldn't be blocked
128 * regardless of 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:
143 EXPORT_SYMBOL_GPL(pstore_cannot_block_path);
145 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
146 static int zbufsize_deflate(size_t size)
151 /* buffer range for efivars */
161 /* buffer range for nvram, erst */
170 return (size * 100) / cmpr;
174 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
175 static int zbufsize_lzo(size_t size)
177 return lzo1x_worst_compress(size);
181 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
182 static int zbufsize_lz4(size_t size)
184 return LZ4_compressBound(size);
188 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
189 static int zbufsize_842(size_t size)
195 static const struct pstore_zbackend *zbackend __ro_after_init;
197 static const struct pstore_zbackend zbackends[] = {
198 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
200 .zbufsize = zbufsize_deflate,
204 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
206 .zbufsize = zbufsize_lzo,
210 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
212 .zbufsize = zbufsize_lz4,
216 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
218 .zbufsize = zbufsize_lz4,
222 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
224 .zbufsize = zbufsize_842,
231 static int pstore_compress(const void *in, void *out,
232 unsigned int inlen, unsigned int outlen)
236 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
238 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
245 static int pstore_decompress(void *in, void *out,
246 unsigned int inlen, unsigned int outlen)
250 ret = crypto_comp_decompress(tfm, in, inlen, out, &outlen);
252 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
259 static void allocate_buf_for_compression(void)
261 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
264 if (!crypto_has_comp(zbackend->name, 0, 0)) {
265 pr_err("No %s compression\n", zbackend->name);
269 big_oops_buf_sz = zbackend->zbufsize(psinfo->bufsize);
270 if (big_oops_buf_sz <= 0)
273 big_oops_buf = kmalloc(big_oops_buf_sz, GFP_KERNEL);
275 pr_err("allocate compression buffer error!\n");
279 tfm = crypto_alloc_comp(zbackend->name, 0, 0);
280 if (IS_ERR_OR_NULL(tfm)) {
283 pr_err("crypto_alloc_comp() failed!\n");
288 static void free_buf_for_compression(void)
290 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && !IS_ERR_OR_NULL(tfm))
291 crypto_free_comp(tfm);
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
304 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
309 total_len = hsize + len;
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;
318 memcpy(psinfo->buf, big_oops_buf, total_len);
323 void pstore_record_init(struct pstore_record *record,
324 struct pstore_info *psinfo)
326 memset(record, 0, sizeof(*record));
328 record->psi = psinfo;
330 /* Report zeroed timestamp if called before timekeeping has resumed. */
331 record->time = ns_to_timespec(ktime_get_real_fast_ns());
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.
339 static void pstore_dump(struct kmsg_dumper *dumper,
340 enum kmsg_dump_reason reason)
342 unsigned long total = 0;
344 unsigned int part = 1;
345 unsigned long flags = 0;
349 why = get_reason_str(reason);
351 if (pstore_cannot_block_path(reason)) {
352 is_locked = spin_trylock_irqsave(&psinfo->buf_lock, flags);
354 pr_err("pstore dump routine blocked in %s path, may corrupt error record\n"
355 , in_nmi() ? "NMI" : why);
359 spin_lock_irqsave(&psinfo->buf_lock, flags);
363 while (total < kmsg_bytes) {
369 struct pstore_record record;
371 pstore_record_init(&record, psinfo);
372 record.type = PSTORE_TYPE_DMESG;
373 record.count = oopscount;
374 record.reason = reason;
376 record.buf = psinfo->buf;
378 if (big_oops_buf && is_locked) {
380 dst_size = big_oops_buf_sz;
383 dst_size = psinfo->bufsize;
386 /* Write dump header. */
387 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
389 dst_size -= header_size;
391 /* Write dump contents. */
392 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
393 dst_size, &dump_size))
396 if (big_oops_buf && is_locked) {
397 zipped_len = pstore_compress(dst, psinfo->buf,
398 header_size + dump_size,
401 if (zipped_len > 0) {
402 record.compressed = true;
403 record.size = zipped_len;
405 record.size = copy_kmsg_to_buffer(header_size,
409 record.size = header_size + dump_size;
412 ret = psinfo->write(&record);
413 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
414 pstore_new_entry = 1;
416 total += record.size;
420 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
423 static struct kmsg_dumper pstore_dumper = {
428 * Register with kmsg_dump to save last part of console log on panic.
430 static void pstore_register_kmsg(void)
432 kmsg_dump_register(&pstore_dumper);
435 static void pstore_unregister_kmsg(void)
437 kmsg_dump_unregister(&pstore_dumper);
440 #ifdef CONFIG_PSTORE_CONSOLE
441 static void pstore_console_write(struct console *con, const char *s, unsigned c)
443 const char *e = s + c;
446 struct pstore_record record;
449 pstore_record_init(&record, psinfo);
450 record.type = PSTORE_TYPE_CONSOLE;
452 if (c > psinfo->bufsize)
455 if (oops_in_progress) {
456 if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
459 spin_lock_irqsave(&psinfo->buf_lock, flags);
461 record.buf = (char *)s;
463 psinfo->write(&record);
464 spin_unlock_irqrestore(&psinfo->buf_lock, flags);
470 static struct console pstore_console = {
472 .write = pstore_console_write,
473 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
477 static void pstore_register_console(void)
479 register_console(&pstore_console);
482 static void pstore_unregister_console(void)
484 unregister_console(&pstore_console);
487 static void pstore_register_console(void) {}
488 static void pstore_unregister_console(void) {}
491 static int pstore_write_user_compat(struct pstore_record *record,
492 const char __user *buf)
499 record->buf = memdup_user(buf, record->size);
500 if (IS_ERR(record->buf)) {
501 ret = PTR_ERR(record->buf);
505 ret = record->psi->write(record);
511 return unlikely(ret < 0) ? ret : record->size;
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
521 int pstore_register(struct pstore_info *psi)
523 struct module *owner = psi->owner;
525 if (backend && strcmp(backend, psi->name)) {
526 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
530 /* Sanity check flags. */
532 pr_warn("backend '%s' must support at least one frontend\n",
537 /* Check for required functions. */
538 if (!psi->read || !psi->write) {
539 pr_warn("backend '%s' must implement read() and write()\n",
544 spin_lock(&pstore_lock);
546 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
547 psinfo->name, psi->name);
548 spin_unlock(&pstore_lock);
552 if (!psi->write_user)
553 psi->write_user = pstore_write_user_compat;
555 mutex_init(&psinfo->read_mutex);
556 spin_unlock(&pstore_lock);
558 if (owner && !try_module_get(owner)) {
563 allocate_buf_for_compression();
565 if (pstore_is_mounted())
566 pstore_get_records(0);
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();
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);
585 * Update the module parameter backend, so it is visible
586 * through /sys/module/pstore/parameters/backend
590 pr_info("Registered %s as persistent store backend\n", psi->name);
596 EXPORT_SYMBOL_GPL(pstore_register);
598 void pstore_unregister(struct pstore_info *psi)
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);
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();
614 free_buf_for_compression();
619 EXPORT_SYMBOL_GPL(pstore_unregister);
621 static void decompress_record(struct pstore_record *record)
626 if (!record->compressed)
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);
635 /* No compression method has created the common buffer. */
637 pr_warn("no decompression buffer allocated\n");
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);
648 /* Build new buffer for decompressed contents. */
649 decompressed = kmalloc(unzipped_len + record->ecc_notice_size,
652 pr_err("decompression ran out of memory\n");
655 memcpy(decompressed, big_oops_buf, unzipped_len);
657 /* Append ECC notice to decompressed buffer. */
658 memcpy(decompressed + unzipped_len, record->buf + record->size,
659 record->ecc_notice_size);
661 /* Swap out compresed contents with decompressed contents. */
663 record->buf = decompressed;
664 record->size = unzipped_len;
665 record->compressed = false;
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
674 void pstore_get_backend_records(struct pstore_info *psi,
675 struct dentry *root, int quiet)
678 unsigned int stop_loop = 65536;
683 mutex_lock(&psi->read_mutex);
684 if (psi->open && psi->open(psi))
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.
692 for (; stop_loop; stop_loop--) {
693 struct pstore_record *record;
696 record = kzalloc(sizeof(*record), GFP_KERNEL);
698 pr_err("out of memory creating record\n");
701 pstore_record_init(record, psi);
703 record->size = psi->read(record);
705 /* No more records left in backend? */
706 if (record->size <= 0) {
711 decompress_record(record);
712 rc = pstore_mkfile(root, record);
714 /* pstore_mkfile() did not take record, so free it. */
717 if (rc != -EEXIST || !quiet)
724 mutex_unlock(&psi->read_mutex);
727 pr_warn("failed to create %d record(s) from '%s'\n",
730 pr_err("looping? Too many records seen from '%s'\n",
734 static void pstore_dowork(struct work_struct *work)
736 pstore_get_records(1);
739 static void pstore_timefunc(struct timer_list *unused)
741 if (pstore_new_entry) {
742 pstore_new_entry = 0;
743 schedule_work(&pstore_work);
746 if (pstore_update_ms >= 0)
747 mod_timer(&pstore_timer,
748 jiffies + msecs_to_jiffies(pstore_update_ms));
751 void __init pstore_choose_compression(void)
753 const struct pstore_zbackend *step;
758 for (step = zbackends; step->name; step++) {
759 if (!strcmp(compress, step->name)) {
761 pr_info("using %s compression\n", zbackend->name);
767 module_param(compress, charp, 0444);
768 MODULE_PARM_DESC(compress, "Pstore compression to use");
770 module_param(backend, charp, 0444);
771 MODULE_PARM_DESC(backend, "Pstore backend to use");