1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Persistent Storage - platform driver interface parts.
4  *
5  * Copyright (C) 2007-2008 Google, Inc.
6  * Copyright (C) 2010 Intel Corporation <tony.luck@intel.com>
7  */
8 
9 #define pr_fmt(fmt) "pstore: " fmt
10 
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>
21 #endif
22 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
23 #include <linux/lz4.h>
24 #endif
25 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
26 #include <linux/zstd.h>
27 #endif
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>
35 
36 #include "internal.h"
37 
38 /*
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
42  */
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)");
49 
50 /* Names should be in the same order as the enum pstore_type_id */
51 static const char * const pstore_type_names[] = {
52 	"dmesg",
53 	"mce",
54 	"console",
55 	"ftrace",
56 	"rtas",
57 	"powerpc-ofw",
58 	"powerpc-common",
59 	"pmsg",
60 	"powerpc-opal",
61 };
62 
63 static int pstore_new_entry;
64 
65 static void pstore_timefunc(struct timer_list *);
66 static DEFINE_TIMER(pstore_timer, pstore_timefunc);
67 
68 static void pstore_dowork(struct work_struct *);
69 static DECLARE_WORK(pstore_work, pstore_dowork);
70 
71 /*
72  * psinfo_lock protects "psinfo" during calls to
73  * pstore_register(), pstore_unregister(), and
74  * the filesystem mount/unmount routines.
75  */
76 static DEFINE_MUTEX(psinfo_lock);
77 struct pstore_info *psinfo;
78 
79 static char *backend;
80 module_param(backend, charp, 0444);
81 MODULE_PARM_DESC(backend, "specific backend to use");
82 
83 static char *compress =
84 #ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
85 		CONFIG_PSTORE_COMPRESS_DEFAULT;
86 #else
87 		NULL;
88 #endif
89 module_param(compress, charp, 0444);
90 MODULE_PARM_DESC(compress, "compression to use");
91 
92 /* How much of the kernel log to snapshot */
93 unsigned long kmsg_bytes = CONFIG_PSTORE_DEFAULT_KMSG_BYTES;
94 module_param(kmsg_bytes, ulong, 0444);
95 MODULE_PARM_DESC(kmsg_bytes, "amount of kernel log to snapshot (in bytes)");
96 
97 /* Compression parameters */
98 static struct crypto_comp *tfm;
99 
100 struct pstore_zbackend {
101 	int (*zbufsize)(size_t size);
102 	const char *name;
103 };
104 
105 static char *big_oops_buf;
106 static size_t big_oops_buf_sz;
107 
pstore_set_kmsg_bytes(int bytes)108 void pstore_set_kmsg_bytes(int bytes)
109 {
110 	kmsg_bytes = bytes;
111 }
112 
113 /* Tag each group of saved records with a sequence number */
114 static int	oopscount;
115 
pstore_type_to_name(enum pstore_type_id type)116 const char *pstore_type_to_name(enum pstore_type_id type)
117 {
118 	BUILD_BUG_ON(ARRAY_SIZE(pstore_type_names) != PSTORE_TYPE_MAX);
119 
120 	if (WARN_ON_ONCE(type >= PSTORE_TYPE_MAX))
121 		return "unknown";
122 
123 	return pstore_type_names[type];
124 }
125 EXPORT_SYMBOL_GPL(pstore_type_to_name);
126 
pstore_name_to_type(const char * name)127 enum pstore_type_id pstore_name_to_type(const char *name)
128 {
129 	int i;
130 
131 	for (i = 0; i < PSTORE_TYPE_MAX; i++) {
132 		if (!strcmp(pstore_type_names[i], name))
133 			return i;
134 	}
135 
136 	return PSTORE_TYPE_MAX;
137 }
138 EXPORT_SYMBOL_GPL(pstore_name_to_type);
139 
pstore_timer_kick(void)140 static void pstore_timer_kick(void)
141 {
142 	if (pstore_update_ms < 0)
143 		return;
144 
145 	mod_timer(&pstore_timer, jiffies + msecs_to_jiffies(pstore_update_ms));
146 }
147 
pstore_cannot_block_path(enum kmsg_dump_reason reason)148 static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
149 {
150 	/*
151 	 * In case of NMI path, pstore shouldn't be blocked
152 	 * regardless of reason.
153 	 */
154 	if (in_nmi())
155 		return true;
156 
157 	switch (reason) {
158 	/* In panic case, other cpus are stopped by smp_send_stop(). */
159 	case KMSG_DUMP_PANIC:
160 	/*
161 	 * Emergency restart shouldn't be blocked by spinning on
162 	 * pstore_info::buf_lock.
163 	 */
164 	case KMSG_DUMP_EMERG:
165 		return true;
166 	default:
167 		return false;
168 	}
169 }
170 
171 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
zbufsize_deflate(size_t size)172 static int zbufsize_deflate(size_t size)
173 {
174 	size_t cmpr;
175 
176 	switch (size) {
177 	/* buffer range for efivars */
178 	case 1000 ... 2000:
179 		cmpr = 56;
180 		break;
181 	case 2001 ... 3000:
182 		cmpr = 54;
183 		break;
184 	case 3001 ... 3999:
185 		cmpr = 52;
186 		break;
187 	/* buffer range for nvram, erst */
188 	case 4000 ... 10000:
189 		cmpr = 45;
190 		break;
191 	default:
192 		cmpr = 60;
193 		break;
194 	}
195 
196 	return (size * 100) / cmpr;
197 }
198 #endif
199 
200 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
zbufsize_lzo(size_t size)201 static int zbufsize_lzo(size_t size)
202 {
203 	return lzo1x_worst_compress(size);
204 }
205 #endif
206 
207 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
zbufsize_lz4(size_t size)208 static int zbufsize_lz4(size_t size)
209 {
210 	return LZ4_compressBound(size);
211 }
212 #endif
213 
214 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
zbufsize_842(size_t size)215 static int zbufsize_842(size_t size)
216 {
217 	return size;
218 }
219 #endif
220 
221 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
zbufsize_zstd(size_t size)222 static int zbufsize_zstd(size_t size)
223 {
224 	return zstd_compress_bound(size);
225 }
226 #endif
227 
228 static const struct pstore_zbackend *zbackend __ro_after_init;
229 
230 static const struct pstore_zbackend zbackends[] = {
231 #if IS_ENABLED(CONFIG_PSTORE_DEFLATE_COMPRESS)
232 	{
233 		.zbufsize	= zbufsize_deflate,
234 		.name		= "deflate",
235 	},
236 #endif
237 #if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
238 	{
239 		.zbufsize	= zbufsize_lzo,
240 		.name		= "lzo",
241 	},
242 #endif
243 #if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS)
244 	{
245 		.zbufsize	= zbufsize_lz4,
246 		.name		= "lz4",
247 	},
248 #endif
249 #if IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
250 	{
251 		.zbufsize	= zbufsize_lz4,
252 		.name		= "lz4hc",
253 	},
254 #endif
255 #if IS_ENABLED(CONFIG_PSTORE_842_COMPRESS)
256 	{
257 		.zbufsize	= zbufsize_842,
258 		.name		= "842",
259 	},
260 #endif
261 #if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
262 	{
263 		.zbufsize	= zbufsize_zstd,
264 		.name		= "zstd",
265 	},
266 #endif
267 	{ }
268 };
269 
pstore_compress(const void * in,void * out,unsigned int inlen,unsigned int outlen)270 static int pstore_compress(const void *in, void *out,
271 			   unsigned int inlen, unsigned int outlen)
272 {
273 	int ret;
274 
275 	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
276 		return -EINVAL;
277 
278 	ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
279 	if (ret) {
280 		pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
281 		return ret;
282 	}
283 
284 	return outlen;
285 }
286 
allocate_buf_for_compression(void)287 static void allocate_buf_for_compression(void)
288 {
289 	struct crypto_comp *ctx;
290 	int size;
291 	char *buf;
292 
293 	/* Skip if not built-in or compression backend not selected yet. */
294 	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !zbackend)
295 		return;
296 
297 	/* Skip if no pstore backend yet or compression init already done. */
298 	if (!psinfo || tfm)
299 		return;
300 
301 	if (!crypto_has_comp(zbackend->name, 0, 0)) {
302 		pr_err("Unknown compression: %s\n", zbackend->name);
303 		return;
304 	}
305 
306 	size = zbackend->zbufsize(psinfo->bufsize);
307 	if (size <= 0) {
308 		pr_err("Invalid compression size for %s: %d\n",
309 		       zbackend->name, size);
310 		return;
311 	}
312 
313 	buf = kmalloc(size, GFP_KERNEL);
314 	if (!buf) {
315 		pr_err("Failed %d byte compression buffer allocation for: %s\n",
316 		       size, zbackend->name);
317 		return;
318 	}
319 
320 	ctx = crypto_alloc_comp(zbackend->name, 0, 0);
321 	if (IS_ERR_OR_NULL(ctx)) {
322 		kfree(buf);
323 		pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
324 		       PTR_ERR(ctx));
325 		return;
326 	}
327 
328 	/* A non-NULL big_oops_buf indicates compression is available. */
329 	tfm = ctx;
330 	big_oops_buf_sz = size;
331 	big_oops_buf = buf;
332 
333 	pr_info("Using crash dump compression: %s\n", zbackend->name);
334 }
335 
free_buf_for_compression(void)336 static void free_buf_for_compression(void)
337 {
338 	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
339 		crypto_free_comp(tfm);
340 		tfm = NULL;
341 	}
342 	kfree(big_oops_buf);
343 	big_oops_buf = NULL;
344 	big_oops_buf_sz = 0;
345 }
346 
347 /*
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
353  */
copy_kmsg_to_buffer(int hsize,size_t len)354 static size_t copy_kmsg_to_buffer(int hsize, size_t len)
355 {
356 	size_t total_len;
357 	size_t diff;
358 
359 	total_len = hsize + len;
360 
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;
367 	} else
368 		memcpy(psinfo->buf, big_oops_buf, total_len);
369 
370 	return total_len;
371 }
372 
pstore_record_init(struct pstore_record * record,struct pstore_info * psinfo)373 void pstore_record_init(struct pstore_record *record,
374 			struct pstore_info *psinfo)
375 {
376 	memset(record, 0, sizeof(*record));
377 
378 	record->psi = psinfo;
379 
380 	/* Report zeroed timestamp if called before timekeeping has resumed. */
381 	record->time = ns_to_timespec64(ktime_get_real_fast_ns());
382 }
383 
384 /*
385  * callback from kmsg_dump. Save as much as we can (up to kmsg_bytes) from the
386  * end of the buffer.
387  */
pstore_dump(struct kmsg_dumper * dumper,enum kmsg_dump_reason reason)388 static void pstore_dump(struct kmsg_dumper *dumper,
389 			enum kmsg_dump_reason reason)
390 {
391 	struct kmsg_dump_iter iter;
392 	unsigned long	total = 0;
393 	const char	*why;
394 	unsigned int	part = 1;
395 	unsigned long	flags = 0;
396 	int		saved_ret = 0;
397 	int		ret;
398 
399 	why = kmsg_dump_reason_str(reason);
400 
401 	if (pstore_cannot_block_path(reason)) {
402 		if (!spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
403 			pr_err("dump skipped in %s path because of concurrent dump\n",
404 					in_nmi() ? "NMI" : why);
405 			return;
406 		}
407 	} else {
408 		spin_lock_irqsave(&psinfo->buf_lock, flags);
409 	}
410 
411 	kmsg_dump_rewind(&iter);
412 
413 	oopscount++;
414 	while (total < kmsg_bytes) {
415 		char *dst;
416 		size_t dst_size;
417 		int header_size;
418 		int zipped_len = -1;
419 		size_t dump_size;
420 		struct pstore_record record;
421 
422 		pstore_record_init(&record, psinfo);
423 		record.type = PSTORE_TYPE_DMESG;
424 		record.count = oopscount;
425 		record.reason = reason;
426 		record.part = part;
427 		record.buf = psinfo->buf;
428 
429 		if (big_oops_buf) {
430 			dst = big_oops_buf;
431 			dst_size = big_oops_buf_sz;
432 		} else {
433 			dst = psinfo->buf;
434 			dst_size = psinfo->bufsize;
435 		}
436 
437 		/* Write dump header. */
438 		header_size = snprintf(dst, dst_size, "%s#%d Part%u\n", why,
439 				 oopscount, part);
440 		dst_size -= header_size;
441 
442 		/* Write dump contents. */
443 		if (!kmsg_dump_get_buffer(&iter, true, dst + header_size,
444 					  dst_size, &dump_size))
445 			break;
446 
447 		if (big_oops_buf) {
448 			zipped_len = pstore_compress(dst, psinfo->buf,
449 						header_size + dump_size,
450 						psinfo->bufsize);
451 
452 			if (zipped_len > 0) {
453 				record.compressed = true;
454 				record.size = zipped_len;
455 			} else {
456 				record.size = copy_kmsg_to_buffer(header_size,
457 								  dump_size);
458 			}
459 		} else {
460 			record.size = header_size + dump_size;
461 		}
462 
463 		ret = psinfo->write(&record);
464 		if (ret == 0 && reason == KMSG_DUMP_OOPS) {
465 			pstore_new_entry = 1;
466 			pstore_timer_kick();
467 		} else {
468 			/* Preserve only the first non-zero returned value. */
469 			if (!saved_ret)
470 				saved_ret = ret;
471 		}
472 
473 		total += record.size;
474 		part++;
475 	}
476 	spin_unlock_irqrestore(&psinfo->buf_lock, flags);
477 
478 	if (saved_ret) {
479 		pr_err_once("backend (%s) writing error (%d)\n", psinfo->name,
480 			    saved_ret);
481 	}
482 }
483 
484 static struct kmsg_dumper pstore_dumper = {
485 	.dump = pstore_dump,
486 };
487 
488 /*
489  * Register with kmsg_dump to save last part of console log on panic.
490  */
pstore_register_kmsg(void)491 static void pstore_register_kmsg(void)
492 {
493 	kmsg_dump_register(&pstore_dumper);
494 }
495 
pstore_unregister_kmsg(void)496 static void pstore_unregister_kmsg(void)
497 {
498 	kmsg_dump_unregister(&pstore_dumper);
499 }
500 
501 #ifdef CONFIG_PSTORE_CONSOLE
pstore_console_write(struct console * con,const char * s,unsigned c)502 static void pstore_console_write(struct console *con, const char *s, unsigned c)
503 {
504 	struct pstore_record record;
505 
506 	if (!c)
507 		return;
508 
509 	pstore_record_init(&record, psinfo);
510 	record.type = PSTORE_TYPE_CONSOLE;
511 
512 	record.buf = (char *)s;
513 	record.size = c;
514 	psinfo->write(&record);
515 }
516 
517 static struct console pstore_console = {
518 	.write	= pstore_console_write,
519 	.index	= -1,
520 };
521 
pstore_register_console(void)522 static void pstore_register_console(void)
523 {
524 	/* Show which backend is going to get console writes. */
525 	strscpy(pstore_console.name, psinfo->name,
526 		sizeof(pstore_console.name));
527 	/*
528 	 * Always initialize flags here since prior unregister_console()
529 	 * calls may have changed settings (specifically CON_ENABLED).
530 	 */
531 	pstore_console.flags = CON_PRINTBUFFER | CON_ENABLED | CON_ANYTIME;
532 	register_console(&pstore_console);
533 }
534 
pstore_unregister_console(void)535 static void pstore_unregister_console(void)
536 {
537 	unregister_console(&pstore_console);
538 }
539 #else
pstore_register_console(void)540 static void pstore_register_console(void) {}
pstore_unregister_console(void)541 static void pstore_unregister_console(void) {}
542 #endif
543 
pstore_write_user_compat(struct pstore_record * record,const char __user * buf)544 static int pstore_write_user_compat(struct pstore_record *record,
545 				    const char __user *buf)
546 {
547 	int ret = 0;
548 
549 	if (record->buf)
550 		return -EINVAL;
551 
552 	record->buf = memdup_user(buf, record->size);
553 	if (IS_ERR(record->buf)) {
554 		ret = PTR_ERR(record->buf);
555 		goto out;
556 	}
557 
558 	ret = record->psi->write(record);
559 
560 	kfree(record->buf);
561 out:
562 	record->buf = NULL;
563 
564 	return unlikely(ret < 0) ? ret : record->size;
565 }
566 
567 /*
568  * platform specific persistent storage driver registers with
569  * us here. If pstore is already mounted, call the platform
570  * read function right away to populate the file system. If not
571  * then the pstore mount code will call us later to fill out
572  * the file system.
573  */
pstore_register(struct pstore_info * psi)574 int pstore_register(struct pstore_info *psi)
575 {
576 	if (backend && strcmp(backend, psi->name)) {
577 		pr_warn("backend '%s' already in use: ignoring '%s'\n",
578 			backend, psi->name);
579 		return -EBUSY;
580 	}
581 
582 	/* Sanity check flags. */
583 	if (!psi->flags) {
584 		pr_warn("backend '%s' must support at least one frontend\n",
585 			psi->name);
586 		return -EINVAL;
587 	}
588 
589 	/* Check for required functions. */
590 	if (!psi->read || !psi->write) {
591 		pr_warn("backend '%s' must implement read() and write()\n",
592 			psi->name);
593 		return -EINVAL;
594 	}
595 
596 	mutex_lock(&psinfo_lock);
597 	if (psinfo) {
598 		pr_warn("backend '%s' already loaded: ignoring '%s'\n",
599 			psinfo->name, psi->name);
600 		mutex_unlock(&psinfo_lock);
601 		return -EBUSY;
602 	}
603 
604 	if (!psi->write_user)
605 		psi->write_user = pstore_write_user_compat;
606 	psinfo = psi;
607 	mutex_init(&psinfo->read_mutex);
608 	spin_lock_init(&psinfo->buf_lock);
609 
610 	if (psi->flags & PSTORE_FLAGS_DMESG)
611 		allocate_buf_for_compression();
612 
613 	pstore_get_records(0);
614 
615 	if (psi->flags & PSTORE_FLAGS_DMESG) {
616 		pstore_dumper.max_reason = psinfo->max_reason;
617 		pstore_register_kmsg();
618 	}
619 	if (psi->flags & PSTORE_FLAGS_CONSOLE)
620 		pstore_register_console();
621 	if (psi->flags & PSTORE_FLAGS_FTRACE)
622 		pstore_register_ftrace();
623 	if (psi->flags & PSTORE_FLAGS_PMSG)
624 		pstore_register_pmsg();
625 
626 	/* Start watching for new records, if desired. */
627 	pstore_timer_kick();
628 
629 	/*
630 	 * Update the module parameter backend, so it is visible
631 	 * through /sys/module/pstore/parameters/backend
632 	 */
633 	backend = kstrdup(psi->name, GFP_KERNEL);
634 
635 	pr_info("Registered %s as persistent store backend\n", psi->name);
636 
637 	mutex_unlock(&psinfo_lock);
638 	return 0;
639 }
640 EXPORT_SYMBOL_GPL(pstore_register);
641 
pstore_unregister(struct pstore_info * psi)642 void pstore_unregister(struct pstore_info *psi)
643 {
644 	/* It's okay to unregister nothing. */
645 	if (!psi)
646 		return;
647 
648 	mutex_lock(&psinfo_lock);
649 
650 	/* Only one backend can be registered at a time. */
651 	if (WARN_ON(psi != psinfo)) {
652 		mutex_unlock(&psinfo_lock);
653 		return;
654 	}
655 
656 	/* Unregister all callbacks. */
657 	if (psi->flags & PSTORE_FLAGS_PMSG)
658 		pstore_unregister_pmsg();
659 	if (psi->flags & PSTORE_FLAGS_FTRACE)
660 		pstore_unregister_ftrace();
661 	if (psi->flags & PSTORE_FLAGS_CONSOLE)
662 		pstore_unregister_console();
663 	if (psi->flags & PSTORE_FLAGS_DMESG)
664 		pstore_unregister_kmsg();
665 
666 	/* Stop timer and make sure all work has finished. */
667 	del_timer_sync(&pstore_timer);
668 	flush_work(&pstore_work);
669 
670 	/* Remove all backend records from filesystem tree. */
671 	pstore_put_backend_records(psi);
672 
673 	free_buf_for_compression();
674 
675 	psinfo = NULL;
676 	kfree(backend);
677 	backend = NULL;
678 
679 	pr_info("Unregistered %s as persistent store backend\n", psi->name);
680 	mutex_unlock(&psinfo_lock);
681 }
682 EXPORT_SYMBOL_GPL(pstore_unregister);
683 
decompress_record(struct pstore_record * record)684 static void decompress_record(struct pstore_record *record)
685 {
686 	int ret;
687 	int unzipped_len;
688 	char *unzipped, *workspace;
689 
690 	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
691 		return;
692 
693 	/* Only PSTORE_TYPE_DMESG support compression. */
694 	if (record->type != PSTORE_TYPE_DMESG) {
695 		pr_warn("ignored compressed record type %d\n", record->type);
696 		return;
697 	}
698 
699 	/* Missing compression buffer means compression was not initialized. */
700 	if (!big_oops_buf) {
701 		pr_warn("no decompression method initialized!\n");
702 		return;
703 	}
704 
705 	/* Allocate enough space to hold max decompression and ECC. */
706 	unzipped_len = big_oops_buf_sz;
707 	workspace = kmalloc(unzipped_len + record->ecc_notice_size,
708 			    GFP_KERNEL);
709 	if (!workspace)
710 		return;
711 
712 	/* After decompression "unzipped_len" is almost certainly smaller. */
713 	ret = crypto_comp_decompress(tfm, record->buf, record->size,
714 					  workspace, &unzipped_len);
715 	if (ret) {
716 		pr_err("crypto_comp_decompress failed, ret = %d!\n", ret);
717 		kfree(workspace);
718 		return;
719 	}
720 
721 	/* Append ECC notice to decompressed buffer. */
722 	memcpy(workspace + unzipped_len, record->buf + record->size,
723 	       record->ecc_notice_size);
724 
725 	/* Copy decompressed contents into an minimum-sized allocation. */
726 	unzipped = kmemdup(workspace, unzipped_len + record->ecc_notice_size,
727 			   GFP_KERNEL);
728 	kfree(workspace);
729 	if (!unzipped)
730 		return;
731 
732 	/* Swap out compressed contents with decompressed contents. */
733 	kfree(record->buf);
734 	record->buf = unzipped;
735 	record->size = unzipped_len;
736 	record->compressed = false;
737 }
738 
739 /*
740  * Read all the records from one persistent store backend. Create
741  * files in our filesystem.  Don't warn about -EEXIST errors
742  * when we are re-scanning the backing store looking to add new
743  * error records.
744  */
pstore_get_backend_records(struct pstore_info * psi,struct dentry * root,int quiet)745 void pstore_get_backend_records(struct pstore_info *psi,
746 				struct dentry *root, int quiet)
747 {
748 	int failed = 0;
749 	unsigned int stop_loop = 65536;
750 
751 	if (!psi || !root)
752 		return;
753 
754 	mutex_lock(&psi->read_mutex);
755 	if (psi->open && psi->open(psi))
756 		goto out;
757 
758 	/*
759 	 * Backend callback read() allocates record.buf. decompress_record()
760 	 * may reallocate record.buf. On success, pstore_mkfile() will keep
761 	 * the record.buf, so free it only on failure.
762 	 */
763 	for (; stop_loop; stop_loop--) {
764 		struct pstore_record *record;
765 		int rc;
766 
767 		record = kzalloc(sizeof(*record), GFP_KERNEL);
768 		if (!record) {
769 			pr_err("out of memory creating record\n");
770 			break;
771 		}
772 		pstore_record_init(record, psi);
773 
774 		record->size = psi->read(record);
775 
776 		/* No more records left in backend? */
777 		if (record->size <= 0) {
778 			kfree(record);
779 			break;
780 		}
781 
782 		decompress_record(record);
783 		rc = pstore_mkfile(root, record);
784 		if (rc) {
785 			/* pstore_mkfile() did not take record, so free it. */
786 			kfree(record->buf);
787 			kfree(record->priv);
788 			kfree(record);
789 			if (rc != -EEXIST || !quiet)
790 				failed++;
791 		}
792 	}
793 	if (psi->close)
794 		psi->close(psi);
795 out:
796 	mutex_unlock(&psi->read_mutex);
797 
798 	if (failed)
799 		pr_warn("failed to create %d record(s) from '%s'\n",
800 			failed, psi->name);
801 	if (!stop_loop)
802 		pr_err("looping? Too many records seen from '%s'\n",
803 			psi->name);
804 }
805 
pstore_dowork(struct work_struct * work)806 static void pstore_dowork(struct work_struct *work)
807 {
808 	pstore_get_records(1);
809 }
810 
pstore_timefunc(struct timer_list * unused)811 static void pstore_timefunc(struct timer_list *unused)
812 {
813 	if (pstore_new_entry) {
814 		pstore_new_entry = 0;
815 		schedule_work(&pstore_work);
816 	}
817 
818 	pstore_timer_kick();
819 }
820 
pstore_choose_compression(void)821 static void __init pstore_choose_compression(void)
822 {
823 	const struct pstore_zbackend *step;
824 
825 	if (!compress)
826 		return;
827 
828 	for (step = zbackends; step->name; step++) {
829 		if (!strcmp(compress, step->name)) {
830 			zbackend = step;
831 			return;
832 		}
833 	}
834 }
835 
pstore_init(void)836 static int __init pstore_init(void)
837 {
838 	int ret;
839 
840 	pstore_choose_compression();
841 
842 	/*
843 	 * Check if any pstore backends registered earlier but did not
844 	 * initialize compression because crypto was not ready. If so,
845 	 * initialize compression now.
846 	 */
847 	allocate_buf_for_compression();
848 
849 	ret = pstore_init_fs();
850 	if (ret)
851 		free_buf_for_compression();
852 
853 	return ret;
854 }
855 late_initcall(pstore_init);
856 
pstore_exit(void)857 static void __exit pstore_exit(void)
858 {
859 	pstore_exit_fs();
860 }
861 module_exit(pstore_exit)
862 
863 MODULE_AUTHOR("Tony Luck <tony.luck@intel.com>");
864 MODULE_LICENSE("GPL");
865