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 is not 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 * pstore_lock just protects "psinfo" during
73 * calls to pstore_register()
75 static DEFINE_SPINLOCK(pstore_lock);
76 struct pstore_info *psinfo;
79 static char *compress =
80 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
81 CONFIG_PSTORE_COMPRESS_DEFAULT;
86 /* Compression parameters */
87 static struct crypto_comp *tfm;
89 struct pstore_zbackend {
90 int (*zbufsize)(size_t size);
94 static char *big_oops_buf;
95 static size_t big_oops_buf_sz;
97 /* How much of the console log to snapshot */
98 unsigned long kmsg_bytes = PSTORE_DEFAULT_KMSG_BYTES;
100 void pstore_set_kmsg_bytes(int bytes)
105 /* Tag each group of saved records with a sequence number */
106 static int oopscount;
108 const char *pstore_type_to_name(enum pstore_type_id type)
110 BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
112 if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
115 return pstore_type_names[type];
117 EXPORT_SYMBOL_GPL(pstore_type_to_name);
119 enum pstore_type_id pstore_name_to_type(const char *name)
123 for (i = 0; i < PSTORE_TYPE_MAX; i++) {
124 if (!strcmp(pstore_type_names[i], name))
128 return PSTORE_TYPE_MAX;
130 EXPORT_SYMBOL_GPL(pstore_name_to_type);
132 static const char *get_reason_str(enum kmsg_dump_reason reason)
135 case KMSG_DUMP_PANIC:
139 case KMSG_DUMP_EMERG:
141 case KMSG_DUMP_RESTART:
145 case KMSG_DUMP_POWEROFF:
153 * Should pstore_dump() wait for a concurrent pstore_dump()? If
154 * not, the current pstore_dump() will report a failure to dump
157 static bool pstore_cannot_wait(enum kmsg_dump_reason reason)
159 /* In NMI path, pstore shouldn't block regardless of 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:
174 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
175 static int zbufsize_deflate(size_t size)
180 /* buffer range for efivars */
190 /* buffer range for nvram, erst */
199 return (size * 100) / cmpr;
203 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
204 static int zbufsize_lzo(size_t size)
206 return lzo1x_worst_compress(size);
210 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
211 static int zbufsize_lz4(size_t size)
213 return LZ4_compressBound(size);
217 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
218 static int zbufsize_842(size_t size)
224 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
225 static int zbufsize_zstd(size_t size)
227 return ZSTD_compressBound(size);
231 static const struct pstore_zbackend *zbackend __ro_after_init;
233 static const struct pstore_zbackend zbackends[] = {
234 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
236 .zbufsize = zbufsize_deflate,
240 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
242 .zbufsize = zbufsize_lzo,
246 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
248 .zbufsize = zbufsize_lz4,
252 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
254 .zbufsize = zbufsize_lz4,
258 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
260 .zbufsize = zbufsize_842,
264 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
266 .zbufsize = zbufsize_zstd,
273 static int pstore_compress(const void *in, void *out,
274 unsigned int inlen, unsigned int outlen)
278 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
281 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
283 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
290 static void allocate_buf_for_compression(void)
292 struct crypto_comp *ctx;
296 /* Skip if not built-in or compression backend not selected yet. */
297 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
300 /* Skip if no pstore backend yet or compression init already done. */
304 if (!crypto_has_comp(zbackend->name, 0, 0)) {
305 pr_err("Unknown compression: %s\n", zbackend->name);
309 size = zbackend->zbufsize(psinfo->bufsize);
311 pr_err("Invalid compression size for %s: %d\n",
312 zbackend->name, size);
316 buf = kmalloc(size, GFP_KERNEL);
318 pr_err("Failed %d byte compression buffer allocation for: %s\n",
319 size, zbackend->name);
323 ctx = crypto_alloc_comp(zbackend->name, 0, 0);
324 if (IS_ERR_OR_NULL(ctx)) {
326 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
331 /* A non-NULL big_oops_buf indicates compression is available. */
333 big_oops_buf_sz = size;
336 pr_info("Using crash dump compression: %s\n", zbackend->name);
339 static void free_buf_for_compression(void)
341 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
342 crypto_free_comp(tfm);
351 * Called when compression fails, since the printk buffer
352 * would be fetched for compression calling it again when
353 * compression fails would have moved the iterator of
354 * printk buffer which results in fetching old contents.
355 * Copy the recent messages from big_oops_buf to psinfo->buf
357 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
362 total_len = hsize + len;
364 if (total_len > psinfo->bufsize) {
365 diff = total_len - psinfo->bufsize + hsize;
366 memcpy(psinfo->buf, big_oops_buf, hsize);
367 memcpy(psinfo->buf + hsize, big_oops_buf + diff,
368 psinfo->bufsize - hsize);
369 total_len = psinfo->bufsize;
371 memcpy(psinfo->buf, big_oops_buf, total_len);
376 void pstore_record_init(struct pstore_record *record,
377 struct pstore_info *psinfo)
379 memset(record, 0, sizeof(*record));
381 record->psi = psinfo;
383 /* Report zeroed timestamp if called before timekeeping has resumed. */
384 record->time = ns_to_timespec64(ktime_get_real_fast_ns());
388 * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
391 static void pstore_dump(struct kmsg_dumper *dumper,
392 enum kmsg_dump_reason reason)
394 unsigned long total = 0;
396 unsigned int part = 1;
399 why = get_reason_str(reason);
401 if (down_trylock(&psinfo->buf_lock)) {
402 /* Failed to acquire lock: give up if we cannot wait. */
403 if (pstore_cannot_wait(reason)) {
404 pr_err("dump skipped in %s path: may corrupt error record\n",
405 in_nmi() ? "NMI" : why);
408 if (down_interruptible(&psinfo->buf_lock)) {
409 pr_err("could not grab semaphore?!\n");
415 while (total < kmsg_bytes) {
421 struct pstore_record record;
423 pstore_record_init(&record, psinfo);
424 record.type = PSTORE_TYPE_DMESG;
425 record.count = oopscount;
426 record.reason = reason;
428 record.buf = psinfo->buf;
432 dst_size = big_oops_buf_sz;
435 dst_size = psinfo->bufsize;
438 /* Write dump header. */
439 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
441 dst_size -= header_size;
443 /* Write dump contents. */
444 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
445 dst_size, &dump_size))
449 zipped_len = pstore_compress(dst, psinfo->buf,
450 header_size + dump_size,
453 if (zipped_len > 0) {
454 record.compressed = true;
455 record.size = zipped_len;
457 record.size = copy_kmsg_to_buffer(header_size,
461 record.size = header_size + dump_size;
464 ret = psinfo->write(&record);
465 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
466 pstore_new_entry = 1;
468 total += record.size;
472 up(&psinfo->buf_lock);
475 static struct kmsg_dumper pstore_dumper = {
480 * Register with kmsg_dump to save last part of console log on panic.
482 static void pstore_register_kmsg(void)
484 kmsg_dump_register(&pstore_dumper);
487 static void pstore_unregister_kmsg(void)
489 kmsg_dump_unregister(&pstore_dumper);
492 #ifdef CONFIG_PSTORE_CONSOLE
493 static void pstore_console_write(struct console *con, const char *s, unsigned c)
495 struct pstore_record record;
500 pstore_record_init(&record, psinfo);
501 record.type = PSTORE_TYPE_CONSOLE;
503 record.buf = (char *)s;
505 psinfo->write(&record);
508 static struct console pstore_console = {
510 .write = pstore_console_write,
511 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
515 static void pstore_register_console(void)
517 register_console(&pstore_console);
520 static void pstore_unregister_console(void)
522 unregister_console(&pstore_console);
525 static void pstore_register_console(void) {}
526 static void pstore_unregister_console(void) {}
529 static int pstore_write_user_compat(struct pstore_record *record,
530 const char __user *buf)
537 record->buf = memdup_user(buf, record->size);
538 if (IS_ERR(record->buf)) {
539 ret = PTR_ERR(record->buf);
543 ret = record->psi->write(record);
549 return unlikely(ret < 0) ? ret : record->size;
553 * platform specific persistent storage driver registers with
554 * us here. If pstore is already mounted, call the platform
555 * read function right away to populate the file system. If not
556 * then the pstore mount code will call us later to fill out
559 int pstore_register(struct pstore_info *psi)
561 struct module *owner = psi->owner;
563 if (backend && strcmp(backend, psi->name)) {
564 pr_warn("ignoring unexpected backend '%s'\n", psi->name);
568 /* Sanity check flags. */
570 pr_warn("backend '%s' must support at least one frontend\n",
575 /* Check for required functions. */
576 if (!psi->read || !psi->write) {
577 pr_warn("backend '%s' must implement read() and write()\n",
582 spin_lock(&pstore_lock);
584 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
585 psinfo->name, psi->name);
586 spin_unlock(&pstore_lock);
590 if (!psi->write_user)
591 psi->write_user = pstore_write_user_compat;
593 mutex_init(&psinfo->read_mutex);
594 sema_init(&psinfo->buf_lock, 1);
595 spin_unlock(&pstore_lock);
597 if (owner && !try_module_get(owner)) {
602 if (psi->flags & PSTORE_FLAGS_DMESG)
603 allocate_buf_for_compression();
605 if (pstore_is_mounted())
606 pstore_get_records(0);
608 if (psi->flags & PSTORE_FLAGS_DMESG)
609 pstore_register_kmsg();
610 if (psi->flags & PSTORE_FLAGS_CONSOLE)
611 pstore_register_console();
612 if (psi->flags & PSTORE_FLAGS_FTRACE)
613 pstore_register_ftrace();
614 if (psi->flags & PSTORE_FLAGS_PMSG)
615 pstore_register_pmsg();
617 /* Start watching for new records, if desired. */
618 if (pstore_update_ms >= 0) {
619 pstore_timer.expires = jiffies +
620 msecs_to_jiffies(pstore_update_ms);
621 add_timer(&pstore_timer);
625 * Update the module parameter backend, so it is visible
626 * through /sys/module/pstore/parameters/backend
630 pr_info("Registered %s as persistent store backend\n", psi->name);
636 EXPORT_SYMBOL_GPL(pstore_register);
638 void pstore_unregister(struct pstore_info *psi)
640 /* Stop timer and make sure all work has finished. */
641 pstore_update_ms = -1;
642 del_timer_sync(&pstore_timer);
643 flush_work(&pstore_work);
645 if (psi->flags & PSTORE_FLAGS_PMSG)
646 pstore_unregister_pmsg();
647 if (psi->flags & PSTORE_FLAGS_FTRACE)
648 pstore_unregister_ftrace();
649 if (psi->flags & PSTORE_FLAGS_CONSOLE)
650 pstore_unregister_console();
651 if (psi->flags & PSTORE_FLAGS_DMESG)
652 pstore_unregister_kmsg();
654 free_buf_for_compression();
659 EXPORT_SYMBOL_GPL(pstore_unregister);
661 static void decompress_record(struct pstore_record *record)
665 char *unzipped, *workspace;
667 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
670 /* Only PSTORE_TYPE_DMESG support compression. */
671 if (record->type != PSTORE_TYPE_DMESG) {
672 pr_warn("ignored compressed record type %d\n", record->type);
676 /* Missing compression buffer means compression was not initialized. */
678 pr_warn("no decompression method initialized!\n");
682 /* Allocate enough space to hold max decompression and ECC. */
683 unzipped_len = big_oops_buf_sz;
684 workspace = kmalloc(unzipped_len + record->ecc_notice_size,
689 /* After decompression "unzipped_len" is almost certainly smaller. */
690 ret = crypto_comp_decompress(tfm, record->buf, record->size,
691 workspace, &unzipped_len);
693 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
698 /* Append ECC notice to decompressed buffer. */
699 memcpy(workspace + unzipped_len, record->buf + record->size,
700 record->ecc_notice_size);
702 /* Copy decompressed contents into an minimum-sized allocation. */
703 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
709 /* Swap out compressed contents with decompressed contents. */
711 record->buf = unzipped;
712 record->size = unzipped_len;
713 record->compressed = false;
717 * Read all the records from one persistent store backend. Create
718 * files in our filesystem. Don't warn about -EEXIST errors
719 * when we are re-scanning the backing store looking to add new
722 void pstore_get_backend_records(struct pstore_info *psi,
723 struct dentry *root, int quiet)
726 unsigned int stop_loop = 65536;
731 mutex_lock(&psi->read_mutex);
732 if (psi->open && psi->open(psi))
736 * Backend callback read() allocates record.buf. decompress_record()
737 * may reallocate record.buf. On success, pstore_mkfile() will keep
738 * the record.buf, so free it only on failure.
740 for (; stop_loop; stop_loop--) {
741 struct pstore_record *record;
744 record = kzalloc(sizeof(*record), GFP_KERNEL);
746 pr_err("out of memory creating record\n");
749 pstore_record_init(record, psi);
751 record->size = psi->read(record);
753 /* No more records left in backend? */
754 if (record->size <= 0) {
759 decompress_record(record);
760 rc = pstore_mkfile(root, record);
762 /* pstore_mkfile() did not take record, so free it. */
765 if (rc != -EEXIST || !quiet)
772 mutex_unlock(&psi->read_mutex);
775 pr_warn("failed to create %d record(s) from '%s'\n",
778 pr_err("looping? Too many records seen from '%s'\n",
782 static void pstore_dowork(struct work_struct *work)
784 pstore_get_records(1);
787 static void pstore_timefunc(struct timer_list *unused)
789 if (pstore_new_entry) {
790 pstore_new_entry = 0;
791 schedule_work(&pstore_work);
794 if (pstore_update_ms >= 0)
795 mod_timer(&pstore_timer,
796 jiffies + msecs_to_jiffies(pstore_update_ms));
799 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_param(compress, charp, 0444);
842 MODULE_PARM_DESC(compress, "Pstore compression to use");
844 module_param(backend, charp, 0444);
845 MODULE_PARM_DESC(backend, "Pstore backend to use");
847 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
848 MODULE_LICENSE("GPL");