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 ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
280 pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
287 static void allocate_buf_for_compression(void)
289 struct crypto_comp *ctx;
293 /* Skip if not built-in or compression backend not selected yet. */
294 if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
297 /* Skip if no pstore backend yet or compression init already done. */
301 if (!crypto_has_comp(zbackend->name, 0, 0)) {
302 pr_err("Unknown compression: %s\n", zbackend->name);
306 size = zbackend->zbufsize(psinfo->bufsize);
308 pr_err("Invalid compression size for %s: %d\n",
309 zbackend->name, size);
313 buf = kmalloc(size, GFP_KERNEL);
315 pr_err("Failed %d byte compression buffer allocation for: %s\n",
316 size, zbackend->name);
320 ctx = crypto_alloc_comp(zbackend->name, 0, 0);
321 if (IS_ERR_OR_NULL(ctx)) {
323 pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
328 /* A non-NULL big_oops_buf indicates compression is available. */
330 big_oops_buf_sz = size;
333 pr_info("Using crash dump compression: %s\n", zbackend->name);
336 static void free_buf_for_compression(void)
338 if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
339 crypto_free_comp(tfm);
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
354 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
359 total_len = hsize + len;
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;
368 memcpy(psinfo->buf, big_oops_buf, total_len);
373 void pstore_record_init(struct pstore_record *record,
374 struct pstore_info *psinfo)
376 memset(record, 0, sizeof(*record));
378 record->psi = psinfo;
380 /* Report zeroed timestamp if called before timekeeping has resumed. */
381 record->time = ns_to_timespec64(ktime_get_real_fast_ns());
385 * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
388 static void pstore_dump(struct kmsg_dumper *dumper,
389 enum kmsg_dump_reason reason)
391 unsigned long total = 0;
393 unsigned int part = 1;
396 why = get_reason_str(reason);
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);
405 if (down_interruptible(&psinfo->buf_lock)) {
406 pr_err("could not grab semaphore?!\n");
412 while (total < kmsg_bytes) {
418 struct pstore_record record;
420 pstore_record_init(&record, psinfo);
421 record.type = PSTORE_TYPE_DMESG;
422 record.count = oopscount;
423 record.reason = reason;
425 record.buf = psinfo->buf;
429 dst_size = big_oops_buf_sz;
432 dst_size = psinfo->bufsize;
435 /* Write dump header. */
436 header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
438 dst_size -= header_size;
440 /* Write dump contents. */
441 if (!kmsg_dump_get_buffer(dumper, true, dst + header_size,
442 dst_size, &dump_size))
446 zipped_len = pstore_compress(dst, psinfo->buf,
447 header_size + dump_size,
450 if (zipped_len > 0) {
451 record.compressed = true;
452 record.size = zipped_len;
454 record.size = copy_kmsg_to_buffer(header_size,
458 record.size = header_size + dump_size;
461 ret = psinfo->write(&record);
462 if (ret == 0 && reason == KMSG_DUMP_OOPS && pstore_is_mounted())
463 pstore_new_entry = 1;
465 total += record.size;
469 up(&psinfo->buf_lock);
472 static struct kmsg_dumper pstore_dumper = {
477 * Register with kmsg_dump to save last part of console log on panic.
479 static void pstore_register_kmsg(void)
481 kmsg_dump_register(&pstore_dumper);
484 static void pstore_unregister_kmsg(void)
486 kmsg_dump_unregister(&pstore_dumper);
489 #ifdef CONFIG_PSTORE_CONSOLE
490 static void pstore_console_write(struct console *con, const char *s, unsigned c)
492 struct pstore_record record;
497 pstore_record_init(&record, psinfo);
498 record.type = PSTORE_TYPE_CONSOLE;
500 record.buf = (char *)s;
502 psinfo->write(&record);
505 static struct console pstore_console = {
507 .write = pstore_console_write,
508 .flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME,
512 static void pstore_register_console(void)
514 register_console(&pstore_console);
517 static void pstore_unregister_console(void)
519 unregister_console(&pstore_console);
522 static void pstore_register_console(void) {}
523 static void pstore_unregister_console(void) {}
526 static int pstore_write_user_compat(struct pstore_record *record,
527 const char __user *buf)
534 record->buf = memdup_user(buf, record->size);
535 if (IS_ERR(record->buf)) {
536 ret = PTR_ERR(record->buf);
540 ret = record->psi->write(record);
546 return unlikely(ret < 0) ? ret : record->size;
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
556 int pstore_register(struct pstore_info *psi)
558 struct module *owner = psi->owner;
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 spin_lock(&pstore_lock);
581 pr_warn("backend '%s' already loaded: ignoring '%s'\n",
582 psinfo->name, psi->name);
583 spin_unlock(&pstore_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);
592 spin_unlock(&pstore_lock);
594 if (owner && !try_module_get(owner)) {
599 if (psi->flags & PSTORE_FLAGS_DMESG)
600 allocate_buf_for_compression();
602 if (pstore_is_mounted())
603 pstore_get_records(0);
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();
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);
622 * Update the module parameter backend, so it is visible
623 * through /sys/module/pstore/parameters/backend
627 pr_info("Registered %s as persistent store backend\n", psi->name);
633 EXPORT_SYMBOL_GPL(pstore_register);
635 void pstore_unregister(struct pstore_info *psi)
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);
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();
651 free_buf_for_compression();
656 EXPORT_SYMBOL_GPL(pstore_unregister);
658 static void decompress_record(struct pstore_record *record)
662 char *unzipped, *workspace;
664 if (!record->compressed)
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);
673 /* Missing compression buffer means compression was not initialized. */
675 pr_warn("no decompression method initialized!\n");
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,
686 /* After decompression "unzipped_len" is almost certainly smaller. */
687 ret = crypto_comp_decompress(tfm, record->buf, record->size,
688 workspace, &unzipped_len);
690 pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
695 /* Append ECC notice to decompressed buffer. */
696 memcpy(workspace + unzipped_len, record->buf + record->size,
697 record->ecc_notice_size);
699 /* Copy decompressed contents into an minimum-sized allocation. */
700 unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
706 /* Swap out compressed contents with decompressed contents. */
708 record->buf = unzipped;
709 record->size = unzipped_len;
710 record->compressed = false;
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
719 void pstore_get_backend_records(struct pstore_info *psi,
720 struct dentry *root, int quiet)
723 unsigned int stop_loop = 65536;
728 mutex_lock(&psi->read_mutex);
729 if (psi->open && psi->open(psi))
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.
737 for (; stop_loop; stop_loop--) {
738 struct pstore_record *record;
741 record = kzalloc(sizeof(*record), GFP_KERNEL);
743 pr_err("out of memory creating record\n");
746 pstore_record_init(record, psi);
748 record->size = psi->read(record);
750 /* No more records left in backend? */
751 if (record->size <= 0) {
756 decompress_record(record);
757 rc = pstore_mkfile(root, record);
759 /* pstore_mkfile() did not take record, so free it. */
762 if (rc != -EEXIST || !quiet)
769 mutex_unlock(&psi->read_mutex);
772 pr_warn("failed to create %d record(s) from '%s'\n",
775 pr_err("looping? Too many records seen from '%s'\n",
779 static void pstore_dowork(struct work_struct *work)
781 pstore_get_records(1);
784 static void pstore_timefunc(struct timer_list *unused)
786 if (pstore_new_entry) {
787 pstore_new_entry = 0;
788 schedule_work(&pstore_work);
791 if (pstore_update_ms >= 0)
792 mod_timer(&pstore_timer,
793 jiffies + msecs_to_jiffies(pstore_update_ms));
796 void __init pstore_choose_compression(void)
798 const struct pstore_zbackend *step;
803 for (step = zbackends; step->name; step++) {
804 if (!strcmp(compress, step->name)) {
811 static int __init pstore_init(void)
815 pstore_choose_compression();
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.
822 allocate_buf_for_compression();
824 ret = pstore_init_fs();
830 late_initcall(pstore_init);
832 static void __exit pstore_exit(void)
836 module_exit(pstore_exit)
838 module_param(compress, charp, 0444);
839 MODULE_PARM_DESC(compress, "Pstore compression to use");
841 module_param(backend, charp, 0444);
842 MODULE_PARM_DESC(backend, "Pstore backend to use");
844 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
845 MODULE_LICENSE("GPL");