1 // SPDX-License-Identifier: GPL-2.0-only
3 * Persistent Storage - platform driver interface parts.
5 * Copyright (C) 2007-2008 Google, Inc.
6 * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
9 #define pr_fmt(fmt) "pstore: " fmt
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>
22 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
23 #include <linux/lz4.h>
25 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
26 #include <linux/zstd.h>
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>
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
43 static int pstore_update_ms = -1;
44 module_param_named(update_ms, pstore_update_ms, int, 0600);
45 MODULE_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)");
50 /* Names should be in the same order as the enum pstore_type_id */
51 static const char * const pstore_type_names[] = {
63 static int pstore_new_entry;
65 static void pstore_timefunc(struct timer_list *);
66 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
68 static void pstore_dowork(struct work_struct *);
69 static DECLARE_WORK(pstore_work, pstore_dowork);
72 * psinfo_lock protects "psinfo" during calls to
73 * pstore_register(), pstore_unregister(), and
74 * the filesystem mount/unmount routines.
76 static DEFINE_MUTEX(psinfo_lock);
77 struct pstore_info *psinfo;
80 module_param(backend, charp, 0444);
81 MODULE_PARM_DESC(backend, "specific backend to use");
83 static char *compress =
84 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
85 CONFIG_PSTORE_COMPRESS_DEFAULT;
89 module_param(compress, charp, 0444);
90 MODULE_PARM_DESC(compress, "compression to use");
92 /* Compression parameters */
93 static struct crypto_comp *tfm;
95 struct pstore_zbackend {
96 int (*zbufsize)(size_t size);
100 static char *big_oops_buf;
101 static size_t big_oops_buf_sz;
103 /* How much of the console log to snapshot */
104 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
106 void pstore_set_kmsg_bytes(int bytes)
111 /* Tag each group of saved records with a sequence number */
112 static int oopscount;
114 const char *pstore_type_to_name(enum pstore_type_id type)
116 BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
118 if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
121 return pstore_type_names[type];
123 EXPORT_SYMBOL_GPL(pstore_type_to_name);
125 enum pstore_type_id pstore_name_to_type(const char *name)
129 for (i = 0; i < PSTORE_TYPE_MAX; i++) {
130 if (!strcmp(pstore_type_names[i], name))
134 return PSTORE_TYPE_MAX;
136 EXPORT_SYMBOL_GPL(pstore_name_to_type);
138 static void pstore_timer_kick(void)
140 if (pstore_update_ms < 0)
143 mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
147 * Should pstore_dump() wait for a concurrent pstore_dump()? If
148 * not, the current pstore_dump() will report a failure to dump
151 static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
153 /* In NMI path, pstore shouldn't block regardless of reason. */
158 /* In panic case, other cpus are stopped by smp_send_stop(). */
159 case KMSG_DUMP_PANIC:
160 /* Emergency restart shouldn't be blocked. */
161 case KMSG_DUMP_EMERG:
168 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
169 static int zbufsize_deflate(size_t size)
174 /* buffer range for efivars */
184 /* buffer range for nvram, erst */
193 return (size * 100) / cmpr;
197 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
198 static int zbufsize_lzo(size_t size)
200 return lzo1x_worst_compress(size);
204 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
205 static int zbufsize_lz4(size_t size)
207 return LZ4_compressBound(size);
211 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
212 static int zbufsize_842(size_t size)
218 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
219 static int zbufsize_zstd(size_t size)
221 return ZSTD_compressBound(size);
225 static const struct pstore_zbackend *zbackend __ro_after_init;
227 static const struct pstore_zbackend zbackends[] = {
228 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
230 .zbufsize = zbufsize_deflate,
234 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
236 .zbufsize = zbufsize_lzo,
240 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
242 .zbufsize = zbufsize_lz4,
246 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
248 .zbufsize = zbufsize_lz4,
252 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
254 .zbufsize = zbufsize_842,
258 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
260 .zbufsize = zbufsize_zstd,
267 static int pstore_compress(const void *in, void *out,
268 unsigned int inlen, unsigned int outlen)
272 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
274 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
281 static void allocate_buf_for_compression(void)
283 struct crypto_comp *ctx;
287 /* Skip if not built-in or compression backend not selected yet. */
288 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
291 /* Skip if no pstore backend yet or compression init already done. */
295 if (!crypto_has_comp(zbackend->name, 0, 0)) {
296 pr_err("Unknown compression: %s\n", zbackend->name);
300 size = zbackend->zbufsize(psinfo->bufsize);
302 pr_err("Invalid compression size for %s: %d\n",
303 zbackend->name, size);
307 buf = kmalloc(size, GFP_KERNEL);
309 pr_err("Failed %d byte compression buffer allocation for: %s\n",
310 size, zbackend->name);
314 ctx = crypto_alloc_comp(zbackend->name, 0, 0);
315 if (IS_ERR_OR_NULL(ctx)) {
317 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
322 /* A non-NULL big_oops_buf indicates compression is available. */
324 big_oops_buf_sz = size;
327 pr_info("Using crash dump compression: %s\n", zbackend->name);
330 static void free_buf_for_compression(void)
332 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
333 crypto_free_comp(tfm);
342 * Called when compression fails, since the printk buffer
343 * would be fetched for compression calling it again when
344 * compression fails would have moved the iterator of
345 * printk buffer which results in fetching old contents.
346 * Copy the recent messages from big_oops_buf to psinfo->buf
348 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
353 total_len = hsize + len;
355 if (total_len > psinfo->bufsize) {
356 diff = total_len - psinfo->bufsize + hsize;
357 memcpy(psinfo->buf, big_oops_buf, hsize);
358 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
359 psinfo->bufsize - hsize);
360 total_len = psinfo->bufsize;
362 memcpy(psinfo->buf, big_oops_buf, total_len);
367 void pstore_record_init(struct pstore_record *record,
368 struct pstore_info *psinfo)
370 memset(record, 0, sizeof(*record));
372 record->psi = psinfo;
374 /* Report zeroed timestamp if called before timekeeping has resumed. */
375 record->time = ns_to_timespec64(ktime_get_real_fast_ns());
379 * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
382 static void pstore_dump(struct kmsg_dumper *dumper,
383 enum kmsg_dump_reason reason)
385 unsigned long total = 0;
387 unsigned int part = 1;
390 why = kmsg_dump_reason_str(reason);
392 if (down_trylock(&psinfo->buf_lock)) {
393 /* Failed to acquire lock: give up if we cannot wait. */
394 if (pstore_cannot_wait(reason)) {
395 pr_err("dump skipped in %s path: may corrupt error record\n",
396 in_nmi() ? "NMI" : why);
399 if (down_interruptible(&psinfo->buf_lock)) {
400 pr_err("could not grab semaphore?!\n");
406 while (total < kmsg_bytes) {
412 struct pstore_record record;
414 pstore_record_init(&record, psinfo);
415 record.type = PSTORE_TYPE_DMESG;
416 record.count = oopscount;
417 record.reason = reason;
419 record.buf = psinfo->buf;
423 dst_size = big_oops_buf_sz;
426 dst_size = psinfo->bufsize;
429 /* Write dump header. */
430 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
432 dst_size -= header_size;
434 /* Write dump contents. */
435 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
436 dst_size, &dump_size))
440 zipped_len = pstore_compress(dst, psinfo->buf,
441 header_size + dump_size,
444 if (zipped_len > 0) {
445 record.compressed = true;
446 record.size = zipped_len;
448 record.size = copy_kmsg_to_buffer(header_size,
452 record.size = header_size + dump_size;
455 ret = psinfo->write(&record);
456 if (ret == 0 && reason == KMSG_DUMP_OOPS) {
457 pstore_new_entry = 1;
461 total += record.size;
465 up(&psinfo->buf_lock);
468 static struct kmsg_dumper pstore_dumper = {
473 * Register with kmsg_dump to save last part of console log on panic.
475 static void pstore_register_kmsg(void)
477 kmsg_dump_register(&pstore_dumper);
480 static void pstore_unregister_kmsg(void)
482 kmsg_dump_unregister(&pstore_dumper);
485 #ifdef CONFIG_PSTORE_CONSOLE
486 static void pstore_console_write(struct console *con, const char *s, unsigned c)
488 struct pstore_record record;
493 pstore_record_init(&record, psinfo);
494 record.type = PSTORE_TYPE_CONSOLE;
496 record.buf = (char *)s;
498 psinfo->write(&record);
501 static struct console pstore_console = {
502 .write = pstore_console_write,
506 static void pstore_register_console(void)
508 /* Show which backend is going to get console writes. */
509 strscpy(pstore_console.name, psinfo->name,
510 sizeof(pstore_console.name));
512 * Always initialize flags here since prior unregister_console()
513 * calls may have changed settings (specifically CON_ENABLED).
515 pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
516 register_console(&pstore_console);
519 static void pstore_unregister_console(void)
521 unregister_console(&pstore_console);
524 static void pstore_register_console(void) {}
525 static void pstore_unregister_console(void) {}
528 static int pstore_write_user_compat(struct pstore_record *record,
529 const char __user *buf)
536 record->buf = memdup_user(buf, record->size);
537 if (IS_ERR(record->buf)) {
538 ret = PTR_ERR(record->buf);
542 ret = record->psi->write(record);
548 return unlikely(ret < 0) ? ret : record->size;
552 * platform specific persistent storage driver registers with
553 * us here. If pstore is already mounted, call the platform
554 * read function right away to populate the file system. If not
555 * then the pstore mount code will call us later to fill out
558 int pstore_register(struct pstore_info *psi)
560 if (backend && strcmp(backend, psi->name)) {
561 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
565 /* Sanity check flags. */
567 pr_warn("backend '%s' must support at least one frontend\n",
572 /* Check for required functions. */
573 if (!psi->read || !psi->write) {
574 pr_warn("backend '%s' must implement read() and write()\n",
579 mutex_lock(&psinfo_lock);
581 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
582 psinfo->name, psi->name);
583 mutex_unlock(&psinfo_lock);
587 if (!psi->write_user)
588 psi->write_user = pstore_write_user_compat;
590 mutex_init(&psinfo->read_mutex);
591 sema_init(&psinfo->buf_lock, 1);
593 if (psi->flags & PSTORE_FLAGS_DMESG)
594 allocate_buf_for_compression();
596 pstore_get_records(0);
598 if (psi->flags & PSTORE_FLAGS_DMESG)
599 pstore_register_kmsg();
600 if (psi->flags & PSTORE_FLAGS_CONSOLE)
601 pstore_register_console();
602 if (psi->flags & PSTORE_FLAGS_FTRACE)
603 pstore_register_ftrace();
604 if (psi->flags & PSTORE_FLAGS_PMSG)
605 pstore_register_pmsg();
607 /* Start watching for new records, if desired. */
611 * Update the module parameter backend, so it is visible
612 * through /sys/module/pstore/parameters/backend
614 backend = kstrdup(psi->name, GFP_KERNEL);
616 pr_info("Registered %s as persistent store backend\n", psi->name);
618 mutex_unlock(&psinfo_lock);
621 EXPORT_SYMBOL_GPL(pstore_register);
623 void pstore_unregister(struct pstore_info *psi)
625 /* It's okay to unregister nothing. */
629 mutex_lock(&psinfo_lock);
631 /* Only one backend can be registered at a time. */
632 if (WARN_ON(psi != psinfo)) {
633 mutex_unlock(&psinfo_lock);
637 /* Unregister all callbacks. */
638 if (psi->flags & PSTORE_FLAGS_PMSG)
639 pstore_unregister_pmsg();
640 if (psi->flags & PSTORE_FLAGS_FTRACE)
641 pstore_unregister_ftrace();
642 if (psi->flags & PSTORE_FLAGS_CONSOLE)
643 pstore_unregister_console();
644 if (psi->flags & PSTORE_FLAGS_DMESG)
645 pstore_unregister_kmsg();
647 /* Stop timer and make sure all work has finished. */
648 del_timer_sync(&pstore_timer);
649 flush_work(&pstore_work);
651 /* Remove all backend records from filesystem tree. */
652 pstore_put_backend_records(psi);
654 free_buf_for_compression();
659 mutex_unlock(&psinfo_lock);
661 EXPORT_SYMBOL_GPL(pstore_unregister);
663 static void decompress_record(struct pstore_record *record)
667 char *unzipped, *workspace;
669 if (!record->compressed)
672 /* Only PSTORE_TYPE_DMESG support compression. */
673 if (record->type != PSTORE_TYPE_DMESG) {
674 pr_warn("ignored compressed record type %d\n", record->type);
678 /* Missing compression buffer means compression was not initialized. */
680 pr_warn("no decompression method initialized!\n");
684 /* Allocate enough space to hold max decompression and ECC. */
685 unzipped_len = big_oops_buf_sz;
686 workspace = kmalloc(unzipped_len + record->ecc_notice_size,
691 /* After decompression "unzipped_len" is almost certainly smaller. */
692 ret = crypto_comp_decompress(tfm, record->buf, record->size,
693 workspace, &unzipped_len);
695 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
700 /* Append ECC notice to decompressed buffer. */
701 memcpy(workspace + unzipped_len, record->buf + record->size,
702 record->ecc_notice_size);
704 /* Copy decompressed contents into an minimum-sized allocation. */
705 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
711 /* Swap out compressed contents with decompressed contents. */
713 record->buf = unzipped;
714 record->size = unzipped_len;
715 record->compressed = false;
719 * Read all the records from one persistent store backend. Create
720 * files in our filesystem. Don't warn about -EEXIST errors
721 * when we are re-scanning the backing store looking to add new
724 void pstore_get_backend_records(struct pstore_info *psi,
725 struct dentry *root, int quiet)
728 unsigned int stop_loop = 65536;
733 mutex_lock(&psi->read_mutex);
734 if (psi->open && psi->open(psi))
738 * Backend callback read() allocates record.buf. decompress_record()
739 * may reallocate record.buf. On success, pstore_mkfile() will keep
740 * the record.buf, so free it only on failure.
742 for (; stop_loop; stop_loop--) {
743 struct pstore_record *record;
746 record = kzalloc(sizeof(*record), GFP_KERNEL);
748 pr_err("out of memory creating record\n");
751 pstore_record_init(record, psi);
753 record->size = psi->read(record);
755 /* No more records left in backend? */
756 if (record->size <= 0) {
761 decompress_record(record);
762 rc = pstore_mkfile(root, record);
764 /* pstore_mkfile() did not take record, so free it. */
767 if (rc != -EEXIST || !quiet)
774 mutex_unlock(&psi->read_mutex);
777 pr_warn("failed to create %d record(s) from '%s'\n",
780 pr_err("looping? Too many records seen from '%s'\n",
784 static void pstore_dowork(struct work_struct *work)
786 pstore_get_records(1);
789 static void pstore_timefunc(struct timer_list *unused)
791 if (pstore_new_entry) {
792 pstore_new_entry = 0;
793 schedule_work(&pstore_work);
799 static void __init pstore_choose_compression(void)
801 const struct pstore_zbackend *step;
806 for (step = zbackends; step->name; step++) {
807 if (!strcmp(compress, step->name)) {
814 static int __init pstore_init(void)
818 pstore_choose_compression();
821 * Check if any pstore backends registered earlier but did not
822 * initialize compression because crypto was not ready. If so,
823 * initialize compression now.
825 allocate_buf_for_compression();
827 ret = pstore_init_fs();
829 free_buf_for_compression();
833 late_initcall(pstore_init);
835 static void __exit pstore_exit(void)
839 module_exit(pstore_exit)
841 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
842 MODULE_LICENSE("GPL");