summaryrefslogtreecommitdiff
path: root/fs/pstore/ram.c
blob: ca6d8a86728566520c896cda6b7b7986c3e35e36 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
// SPDX-License-Identifier: GPL-2.0-only
/*
 * RAM Oops/Panic logger
 *
 * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
 * Copyright (C) 2011 Kees Cook <keescook@chromium.org>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/pstore.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/compiler.h>
#include <linux/pstore_ram.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include "internal.h"

#define RAMOOPS_KERNMSG_HDR "===="
#define MIN_MEM_SIZE 4096UL

static ulong record_size = MIN_MEM_SIZE;
module_param(record_size, ulong, 0400);
MODULE_PARM_DESC(record_size,
		"size of each dump done on oops/panic");

static ulong ramoops_console_size = MIN_MEM_SIZE;
module_param_named(console_size, ramoops_console_size, ulong, 0400);
MODULE_PARM_DESC(console_size, "size of kernel console log");

static ulong ramoops_ftrace_size = MIN_MEM_SIZE;
module_param_named(ftrace_size, ramoops_ftrace_size, ulong, 0400);
MODULE_PARM_DESC(ftrace_size, "size of ftrace log");

static ulong ramoops_pmsg_size = MIN_MEM_SIZE;
module_param_named(pmsg_size, ramoops_pmsg_size, ulong, 0400);
MODULE_PARM_DESC(pmsg_size, "size of user space message log");

static unsigned long long mem_address;
module_param_hw(mem_address, ullong, other, 0400);
MODULE_PARM_DESC(mem_address,
		"start of reserved RAM used to store oops/panic logs");

static ulong mem_size;
module_param(mem_size, ulong, 0400);
MODULE_PARM_DESC(mem_size,
		"size of reserved RAM used to store oops/panic logs");

static unsigned int mem_type;
module_param(mem_type, uint, 0400);
MODULE_PARM_DESC(mem_type,
		"set to 1 to try to use unbuffered memory (default 0)");

static int ramoops_max_reason = -1;
module_param_named(max_reason, ramoops_max_reason, int, 0400);
MODULE_PARM_DESC(max_reason,
		 "maximum reason for kmsg dump (default 2: Oops and Panic) ");

static int ramoops_ecc;
module_param_named(ecc, ramoops_ecc, int, 0400);
MODULE_PARM_DESC(ramoops_ecc,
		"if non-zero, the option enables ECC support and specifies "
		"ECC buffer size in bytes (1 is a special value, means 16 "
		"bytes ECC)");

static int ramoops_dump_oops = -1;
module_param_named(dump_oops, ramoops_dump_oops, int, 0400);
MODULE_PARM_DESC(dump_oops,
		 "(deprecated: use max_reason instead) set to 1 to dump oopses & panics, 0 to only dump panics");

struct ramoops_context {
	struct persistent_ram_zone **dprzs;	/* Oops dump zones */
	struct persistent_ram_zone *cprz;	/* Console zone */
	struct persistent_ram_zone **fprzs;	/* Ftrace zones */
	struct persistent_ram_zone *mprz;	/* PMSG zone */
	phys_addr_t phys_addr;
	unsigned long size;
	unsigned int memtype;
	size_t record_size;
	size_t console_size;
	size_t ftrace_size;
	size_t pmsg_size;
	u32 flags;
	struct persistent_ram_ecc_info ecc_info;
	unsigned int max_dump_cnt;
	unsigned int dump_write_cnt;
	/* _read_cnt need clear on ramoops_pstore_open */
	unsigned int dump_read_cnt;
	unsigned int console_read_cnt;
	unsigned int max_ftrace_cnt;
	unsigned int ftrace_read_cnt;
	unsigned int pmsg_read_cnt;
	struct pstore_info pstore;
};

static struct platform_device *dummy;

static int ramoops_pstore_open(struct pstore_info *psi)
{
	struct ramoops_context *cxt = psi->data;

	cxt->dump_read_cnt = 0;
	cxt->console_read_cnt = 0;
	cxt->ftrace_read_cnt = 0;
	cxt->pmsg_read_cnt = 0;
	return 0;
}

static struct persistent_ram_zone *
ramoops_get_next_prz(struct persistent_ram_zone *przs[], int id,
		     struct pstore_record *record)
{
	struct persistent_ram_zone *prz;

	/* Give up if we never existed or have hit the end. */
	if (!przs)
		return NULL;

	prz = przs[id];
	if (!prz)
		return NULL;

	/* Update old/shadowed buffer. */
	if (prz->type == PSTORE_TYPE_DMESG)
		persistent_ram_save_old(prz);

	if (!persistent_ram_old_size(prz))
		return NULL;

	record->type = prz->type;
	record->id = id;

	return prz;
}

static int ramoops_read_kmsg_hdr(char *buffer, struct timespec64 *time,
				  bool *compressed)
{
	char data_type;
	int header_length = 0;

	if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu-%c\n%n",
		   (time64_t *)&time->tv_sec, &time->tv_nsec, &data_type,
		   &header_length) == 3) {
		time->tv_nsec *= 1000;
		if (data_type == 'C')
			*compressed = true;
		else
			*compressed = false;
	} else if (sscanf(buffer, RAMOOPS_KERNMSG_HDR "%lld.%lu\n%n",
			  (time64_t *)&time->tv_sec, &time->tv_nsec,
			  &header_length) == 2) {
		time->tv_nsec *= 1000;
		*compressed = false;
	} else {
		time->tv_sec = 0;
		time->tv_nsec = 0;
		*compressed = false;
	}
	return header_length;
}

static bool prz_ok(struct persistent_ram_zone *prz)
{
	return !!prz && !!(persistent_ram_old_size(prz) +
			   persistent_ram_ecc_string(prz, NULL, 0));
}

static ssize_t ramoops_pstore_read(struct pstore_record *record)
{
	ssize_t size = 0;
	struct ramoops_context *cxt = record->psi->data;
	struct persistent_ram_zone *prz = NULL;
	int header_length = 0;
	bool free_prz = false;

	/*
	 * Ramoops headers provide time stamps for PSTORE_TYPE_DMESG, but
	 * PSTORE_TYPE_CONSOLE and PSTORE_TYPE_FTRACE don't currently have
	 * valid time stamps, so it is initialized to zero.
	 */
	record->time.tv_sec = 0;
	record->time.tv_nsec = 0;
	record->compressed = false;

	/* Find the next valid persistent_ram_zone for DMESG */
	while (cxt->dump_read_cnt < cxt->max_dump_cnt && !prz) {
		prz = ramoops_get_next_prz(cxt->dprzs, cxt->dump_read_cnt++,
					   record);
		if (!prz_ok(prz))
			continue;
		header_length = ramoops_read_kmsg_hdr(persistent_ram_old(prz),
						      &record->time,
						      &record->compressed);
		/* Clear and skip this DMESG record if it has no valid header */
		if (!header_length) {
			persistent_ram_free_old(prz);
			persistent_ram_zap(prz);
			prz = NULL;
		}
	}

	if (!prz_ok(prz) && !cxt->console_read_cnt++)
		prz = ramoops_get_next_prz(&cxt->cprz, 0 /* single */, record);

	if (!prz_ok(prz) && !cxt->pmsg_read_cnt++)
		prz = ramoops_get_next_prz(&cxt->mprz, 0 /* single */, record);

	/* ftrace is last since it may want to dynamically allocate memory. */
	if (!prz_ok(prz)) {
		if (!(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU) &&
		    !cxt->ftrace_read_cnt++) {
			prz = ramoops_get_next_prz(cxt->fprzs, 0 /* single */,
						   record);
		} else {
			/*
			 * Build a new dummy record which combines all the
			 * per-cpu records including metadata and ecc info.
			 */
			struct persistent_ram_zone *tmp_prz, *prz_next;

			tmp_prz = kzalloc(sizeof(struct persistent_ram_zone),
					  GFP_KERNEL);
			if (!tmp_prz)
				return -ENOMEM;
			prz = tmp_prz;
			free_prz = true;

			while (cxt->ftrace_read_cnt < cxt->max_ftrace_cnt) {
				prz_next = ramoops_get_next_prz(cxt->fprzs,
						cxt->ftrace_read_cnt++, record);

				if (!prz_ok(prz_next))
					continue;

				tmp_prz->ecc_info = prz_next->ecc_info;
				tmp_prz->corrected_bytes +=
						prz_next->corrected_bytes;
				tmp_prz->bad_blocks += prz_next->bad_blocks;

				size = pstore_ftrace_combine_log(
						&tmp_prz->old_log,
						&tmp_prz->old_log_size,
						prz_next->old_log,
						prz_next->old_log_size);
				if (size)
					goto out;
			}
			record->id = 0;
		}
	}

	if (!prz_ok(prz)) {
		size = 0;
		goto out;
	}

	size = persistent_ram_old_size(prz) - header_length;

	/* ECC correction notice */
	record->ecc_notice_size = persistent_ram_ecc_string(prz, NULL, 0);

	record->buf = kmalloc(size + record->ecc_notice_size + 1, GFP_KERNEL);
	if (record->buf == NULL) {
		size = -ENOMEM;
		goto out;
	}

	memcpy(record->buf, (char *)persistent_ram_old(prz) + header_length,
	       size);

	persistent_ram_ecc_string(prz, record->buf + size,
				  record->ecc_notice_size + 1);

out:
	if (free_prz) {
		kfree(prz->old_log);
		kfree(prz);
	}

	return size;
}

static size_t ramoops_write_kmsg_hdr(struct persistent_ram_zone *prz,
				     struct pstore_record *record)
{
	char hdr[36]; /* "===="(4), %lld(20), "."(1), %06lu(6), "-%c\n"(3) */
	size_t len;

	len = scnprintf(hdr, sizeof(hdr),
		RAMOOPS_KERNMSG_HDR "%lld.%06lu-%c\n",
		(time64_t)record->time.tv_sec,
		record->time.tv_nsec / 1000,
		record->compressed ? 'C' : 'D');
	persistent_ram_write(prz, hdr, len);

	return len;
}

static int notrace ramoops_pstore_write(struct pstore_record *record)
{
	struct ramoops_context *cxt = record->psi->data;
	struct persistent_ram_zone *prz;
	size_t size, hlen;

	if (record->type == PSTORE_TYPE_CONSOLE) {
		if (!cxt->cprz)
			return -ENOMEM;
		persistent_ram_write(cxt->cprz, record->buf, record->size);
		return 0;
	} else if (record->type == PSTORE_TYPE_FTRACE) {
		int zonenum;

		if (!cxt->fprzs)
			return -ENOMEM;
		/*
		 * Choose zone by if we're using per-cpu buffers.
		 */
		if (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
			zonenum = smp_processor_id();
		else
			zonenum = 0;

		persistent_ram_write(cxt->fprzs[zonenum], record->buf,
				     record->size);
		return 0;
	} else if (record->type == PSTORE_TYPE_PMSG) {
		pr_warn_ratelimited("PMSG shouldn't call %s\n", __func__);
		return -EINVAL;
	}

	if (record->type != PSTORE_TYPE_DMESG)
		return -EINVAL;

	/*
	 * We could filter on record->reason here if we wanted to (which
	 * would duplicate what happened before the "max_reason" setting
	 * was added), but that would defeat the purpose of a system
	 * changing printk.always_kmsg_dump, so instead log everything that
	 * the kmsg dumper sends us, since it should be doing the filtering
	 * based on the combination of printk.always_kmsg_dump and our
	 * requested "max_reason".
	 */

	/*
	 * Explicitly only take the first part of any new crash.
	 * If our buffer is larger than kmsg_bytes, this can never happen,
	 * and if our buffer is smaller than kmsg_bytes, we don't want the
	 * report split across multiple records.
	 */
	if (record->part != 1)
		return -ENOSPC;

	if (!cxt->dprzs)
		return -ENOSPC;

	prz = cxt->dprzs[cxt->dump_write_cnt];

	/*
	 * Since this is a new crash dump, we need to reset the buffer in
	 * case it still has an old dump present. Without this, the new dump
	 * will get appended, which would seriously confuse anything trying
	 * to check dump file contents. Specifically, ramoops_read_kmsg_hdr()
	 * expects to find a dump header in the beginning of buffer data, so
	 * we must to reset the buffer values, in order to ensure that the
	 * header will be written to the beginning of the buffer.
	 */
	persistent_ram_zap(prz);

	/* Build header and append record contents. */
	hlen = ramoops_write_kmsg_hdr(prz, record);
	if (!hlen)
		return -ENOMEM;

	size = record->size;
	if (size + hlen > prz->buffer_size)
		size = prz->buffer_size - hlen;
	persistent_ram_write(prz, record->buf, size);

	cxt->dump_write_cnt = (cxt->dump_write_cnt + 1) % cxt->max_dump_cnt;

	return 0;
}

static int notrace ramoops_pstore_write_user(struct pstore_record *record,
					     const char __user *buf)
{
	if (record->type == PSTORE_TYPE_PMSG) {
		struct ramoops_context *cxt = record->psi->data;

		if (!cxt->mprz)
			return -ENOMEM;
		return persistent_ram_write_user(cxt->mprz, buf, record->size);
	}

	return -EINVAL;
}

static int ramoops_pstore_erase(struct pstore_record *record)
{
	struct ramoops_context *cxt = record->psi->data;
	struct persistent_ram_zone *prz;

	switch (record->type) {
	case PSTORE_TYPE_DMESG:
		if (record->id >= cxt->max_dump_cnt)
			return -EINVAL;
		prz = cxt->dprzs[record->id];
		break;
	case PSTORE_TYPE_CONSOLE:
		prz = cxt->cprz;
		break;
	case PSTORE_TYPE_FTRACE:
		if (record->id >= cxt->max_ftrace_cnt)
			return -EINVAL;
		prz = cxt->fprzs[record->id];
		break;
	case PSTORE_TYPE_PMSG:
		prz = cxt->mprz;
		break;
	default:
		return -EINVAL;
	}

	persistent_ram_free_old(prz);
	persistent_ram_zap(prz);

	return 0;
}

static struct ramoops_context oops_cxt = {
	.pstore = {
		.owner	= THIS_MODULE,
		.name	= "ramoops",
		.open	= ramoops_pstore_open,
		.read	= ramoops_pstore_read,
		.write	= ramoops_pstore_write,
		.write_user	= ramoops_pstore_write_user,
		.erase	= ramoops_pstore_erase,
	},
};

static void ramoops_free_przs(struct ramoops_context *cxt)
{
	int i;

	/* Free dump PRZs */
	if (cxt->dprzs) {
		for (i = 0; i < cxt->max_dump_cnt; i++)
			persistent_ram_free(cxt->dprzs[i]);

		kfree(cxt->dprzs);
		cxt->max_dump_cnt = 0;
	}

	/* Free ftrace PRZs */
	if (cxt->fprzs) {
		for (i = 0; i < cxt->max_ftrace_cnt; i++)
			persistent_ram_free(cxt->fprzs[i]);
		kfree(cxt->fprzs);
		cxt->max_ftrace_cnt = 0;
	}
}

static int ramoops_init_przs(const char *name,
			     struct device *dev, struct ramoops_context *cxt,
			     struct persistent_ram_zone ***przs,
			     phys_addr_t *paddr, size_t mem_sz,
			     ssize_t record_size,
			     unsigned int *cnt, u32 sig, u32 flags)
{
	int err = -ENOMEM;
	int i;
	size_t zone_sz;
	struct persistent_ram_zone **prz_ar;

	/* Allocate nothing for 0 mem_sz or 0 record_size. */
	if (mem_sz == 0 || record_size == 0) {
		*cnt = 0;
		return 0;
	}

	/*
	 * If we have a negative record size, calculate it based on
	 * mem_sz / *cnt. If we have a positive record size, calculate
	 * cnt from mem_sz / record_size.
	 */
	if (record_size < 0) {
		if (*cnt == 0)
			return 0;
		record_size = mem_sz / *cnt;
		if (record_size == 0) {
			dev_err(dev, "%s record size == 0 (%zu / %u)\n",
				name, mem_sz, *cnt);
			goto fail;
		}
	} else {
		*cnt = mem_sz / record_size;
		if (*cnt == 0) {
			dev_err(dev, "%s record count == 0 (%zu / %zu)\n",
				name, mem_sz, record_size);
			goto fail;
		}
	}

	if (*paddr + mem_sz - cxt->phys_addr > cxt->size) {
		dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
			name,
			mem_sz, (unsigned long long)*paddr,
			cxt->size, (unsigned long long)cxt->phys_addr);
		goto fail;
	}

	zone_sz = mem_sz / *cnt;
	if (!zone_sz) {
		dev_err(dev, "%s zone size == 0\n", name);
		goto fail;
	}

	prz_ar = kcalloc(*cnt, sizeof(**przs), GFP_KERNEL);
	if (!prz_ar)
		goto fail;

	for (i = 0; i < *cnt; i++) {
		char *label;

		if (*cnt == 1)
			label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
		else
			label = kasprintf(GFP_KERNEL, "ramoops:%s(%d/%d)",
					  name, i, *cnt - 1);
		prz_ar[i] = persistent_ram_new(*paddr, zone_sz, sig,
					       &cxt->ecc_info,
					       cxt->memtype, flags, label);
		kfree(label);
		if (IS_ERR(prz_ar[i])) {
			err = PTR_ERR(prz_ar[i]);
			dev_err(dev, "failed to request %s mem region (0x%zx@0x%llx): %d\n",
				name, record_size,
				(unsigned long long)*paddr, err);

			while (i > 0) {
				i--;
				persistent_ram_free(prz_ar[i]);
			}
			kfree(prz_ar);
			goto fail;
		}
		*paddr += zone_sz;
		prz_ar[i]->type = pstore_name_to_type(name);
	}

	*przs = prz_ar;
	return 0;

fail:
	*cnt = 0;
	return err;
}

static int ramoops_init_prz(const char *name,
			    struct device *dev, struct ramoops_context *cxt,
			    struct persistent_ram_zone **prz,
			    phys_addr_t *paddr, size_t sz, u32 sig)
{
	char *label;

	if (!sz)
		return 0;

	if (*paddr + sz - cxt->phys_addr > cxt->size) {
		dev_err(dev, "no room for %s mem region (0x%zx@0x%llx) in (0x%lx@0x%llx)\n",
			name, sz, (unsigned long long)*paddr,
			cxt->size, (unsigned long long)cxt->phys_addr);
		return -ENOMEM;
	}

	label = kasprintf(GFP_KERNEL, "ramoops:%s", name);
	*prz = persistent_ram_new(*paddr, sz, sig, &cxt->ecc_info,
				  cxt->memtype, PRZ_FLAG_ZAP_OLD, label);
	kfree(label);
	if (IS_ERR(*prz)) {
		int err = PTR_ERR(*prz);

		dev_err(dev, "failed to request %s mem region (0x%zx@0x%llx): %d\n",
			name, sz, (unsigned long long)*paddr, err);
		return err;
	}

	*paddr += sz;
	(*prz)->type = pstore_name_to_type(name);

	return 0;
}

/* Read a u32 from a dt property and make sure it's safe for an int. */
static int ramoops_parse_dt_u32(struct platform_device *pdev,
				const char *propname,
				u32 default_value, u32 *value)
{
	u32 val32 = 0;
	int ret;

	ret = of_property_read_u32(pdev->dev.of_node, propname, &val32);
	if (ret == -EINVAL) {
		/* field is missing, use default value. */
		val32 = default_value;
	} else if (ret < 0) {
		dev_err(&pdev->dev, "failed to parse property %s: %d\n",
			propname, ret);
		return ret;
	}

	/* Sanity check our results. */
	if (val32 > INT_MAX) {
		dev_err(&pdev->dev, "%s %u > INT_MAX\n", propname, val32);
		return -EOVERFLOW;
	}

	*value = val32;
	return 0;
}

static int ramoops_parse_dt(struct platform_device *pdev,
			    struct ramoops_platform_data *pdata)
{
	struct device_node *of_node = pdev->dev.of_node;
	struct device_node *parent_node;
	struct resource *res;
	u32 value;
	int ret;

	dev_dbg(&pdev->dev, "using Device Tree\n");

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
		dev_err(&pdev->dev,
			"failed to locate DT /reserved-memory resource\n");
		return -EINVAL;
	}

	pdata->mem_size = resource_size(res);
	pdata->mem_address = res->start;
	pdata->mem_type = of_property_read_bool(of_node, "unbuffered");
	/*
	 * Setting "no-dump-oops" is deprecated and will be ignored if
	 * "max_reason" is also specified.
	 */
	if (of_property_read_bool(of_node, "no-dump-oops"))
		pdata->max_reason = KMSG_DUMP_PANIC;
	else
		pdata->max_reason = KMSG_DUMP_OOPS;

#define parse_u32(name, field, default_value) {				\
		ret = ramoops_parse_dt_u32(pdev, name, default_value,	\
					    &value);			\
		if (ret < 0)						\
			return ret;					\
		field = value;						\
	}

	parse_u32("record-size", pdata->record_size, 0);
	parse_u32("console-size", pdata->console_size, 0);
	parse_u32("ftrace-size", pdata->ftrace_size, 0);
	parse_u32("pmsg-size", pdata->pmsg_size, 0);
	parse_u32("ecc-size", pdata->ecc_info.ecc_size, 0);
	parse_u32("flags", pdata->flags, 0);
	parse_u32("max-reason", pdata->max_reason, pdata->max_reason);

#undef parse_u32

	/*
	 * Some old Chromebooks relied on the kernel setting the
	 * console_size and pmsg_size to the record size since that's
	 * what the downstream kernel did.  These same Chromebooks had
	 * "ramoops" straight under the root node which isn't
	 * according to the current upstream bindings (though it was
	 * arguably acceptable under a prior version of the bindings).
	 * Let's make those old Chromebooks work by detecting that
	 * we're not a child of "reserved-memory" and mimicking the
	 * expected behavior.
	 */
	parent_node = of_get_parent(of_node);
	if (!of_node_name_eq(parent_node, "reserved-memory") &&
	    !pdata->console_size && !pdata->ftrace_size &&
	    !pdata->pmsg_size && !pdata->ecc_info.ecc_size) {
		pdata->console_size = pdata->record_size;
		pdata->pmsg_size = pdata->record_size;
	}
	of_node_put(parent_node);

	return 0;
}

static int ramoops_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct ramoops_platform_data *pdata = dev->platform_data;
	struct ramoops_platform_data pdata_local;
	struct ramoops_context *cxt = &oops_cxt;
	size_t dump_mem_sz;
	phys_addr_t paddr;
	int err = -EINVAL;

	/*
	 * Only a single ramoops area allowed at a time, so fail extra
	 * probes.
	 */
	if (cxt->max_dump_cnt) {
		pr_err("already initialized\n");
		goto fail_out;
	}

	if (dev_of_node(dev) && !pdata) {
		pdata = &pdata_local;
		memset(pdata, 0, sizeof(*pdata));

		err = ramoops_parse_dt(pdev, pdata);
		if (err < 0)
			goto fail_out;
	}

	/* Make sure we didn't get bogus platform data pointer. */
	if (!pdata) {
		pr_err("NULL platform data\n");
		goto fail_out;
	}

	if (!pdata->mem_size || (!pdata->record_size && !pdata->console_size &&
			!pdata->ftrace_size && !pdata->pmsg_size)) {
		pr_err("The memory size and the record/console size must be "
			"non-zero\n");
		goto fail_out;
	}

	if (pdata->record_size && !is_power_of_2(pdata->record_size))
		pdata->record_size = rounddown_pow_of_two(pdata->record_size);
	if (pdata->console_size && !is_power_of_2(pdata->console_size))
		pdata->console_size = rounddown_pow_of_two(pdata->console_size);
	if (pdata->ftrace_size && !is_power_of_2(pdata->ftrace_size))
		pdata->ftrace_size = rounddown_pow_of_two(pdata->ftrace_size);
	if (pdata->pmsg_size && !is_power_of_2(pdata->pmsg_size))
		pdata->pmsg_size = rounddown_pow_of_two(pdata->pmsg_size);

	cxt->size = pdata->mem_size;
	cxt->phys_addr = pdata->mem_address;
	cxt->memtype = pdata->mem_type;
	cxt->record_size = pdata->record_size;
	cxt->console_size = pdata->console_size;
	cxt->ftrace_size = pdata->ftrace_size;
	cxt->pmsg_size = pdata->pmsg_size;
	cxt->flags = pdata->flags;
	cxt->ecc_info = pdata->ecc_info;

	paddr = cxt->phys_addr;

	dump_mem_sz = cxt->size - cxt->console_size - cxt->ftrace_size
			- cxt->pmsg_size;
	err = ramoops_init_przs("dmesg", dev, cxt, &cxt->dprzs, &paddr,
				dump_mem_sz, cxt->record_size,
				&cxt->max_dump_cnt, 0, 0);
	if (err)
		goto fail_out;

	err = ramoops_init_prz("console", dev, cxt, &cxt->cprz, &paddr,
			       cxt->console_size, 0);
	if (err)
		goto fail_init_cprz;

	cxt->max_ftrace_cnt = (cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
				? nr_cpu_ids
				: 1;
	err = ramoops_init_przs("ftrace", dev, cxt, &cxt->fprzs, &paddr,
				cxt->ftrace_size, -1,
				&cxt->max_ftrace_cnt, LINUX_VERSION_CODE,
				(cxt->flags & RAMOOPS_FLAG_FTRACE_PER_CPU)
					? PRZ_FLAG_NO_LOCK : 0);
	if (err)
		goto fail_init_fprz;

	err = ramoops_init_prz("pmsg", dev, cxt, &cxt->mprz, &paddr,
				cxt->pmsg_size, 0);
	if (err)
		goto fail_init_mprz;

	cxt->pstore.data = cxt;
	/*
	 * Prepare frontend flags based on which areas are initialized.
	 * For ramoops_init_przs() cases, the "max count" variable tells
	 * if there are regions present. For ramoops_init_prz() cases,
	 * the single region size is how to check.
	 */
	cxt->pstore.flags = 0;
	if (cxt->max_dump_cnt) {
		cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
		cxt->pstore.max_reason = pdata->max_reason;
	}
	if (cxt->console_size)
		cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
	if (cxt->max_ftrace_cnt)
		cxt->pstore.flags |= PSTORE_FLAGS_FTRACE;
	if (cxt->pmsg_size)
		cxt->pstore.flags |= PSTORE_FLAGS_PMSG;

	/*
	 * Since bufsize is only used for dmesg crash dumps, it
	 * must match the size of the dprz record (after PRZ header
	 * and ECC bytes have been accounted for).
	 */
	if (cxt->pstore.flags & PSTORE_FLAGS_DMESG) {
		cxt->pstore.bufsize = cxt->dprzs[0]->buffer_size;
		cxt->pstore.buf = kzalloc(cxt->pstore.bufsize, GFP_KERNEL);
		if (!cxt->pstore.buf) {
			pr_err("cannot allocate pstore crash dump buffer\n");
			err = -ENOMEM;
			goto fail_clear;
		}
	}

	err = pstore_register(&cxt->pstore);
	if (err) {
		pr_err("registering with pstore failed\n");
		goto fail_buf;
	}

	/*
	 * Update the module parameter variables as well so they are visible
	 * through /sys/module/ramoops/parameters/
	 */
	mem_size = pdata->mem_size;
	mem_address = pdata->mem_address;
	record_size = pdata->record_size;
	ramoops_max_reason = pdata->max_reason;
	ramoops_console_size = pdata->console_size;
	ramoops_pmsg_size = pdata->pmsg_size;
	ramoops_ftrace_size = pdata->ftrace_size;

	pr_info("using 0x%lx@0x%llx, ecc: %d\n",
		cxt->size, (unsigned long long)cxt->phys_addr,
		cxt->ecc_info.ecc_size);

	return 0;

fail_buf:
	kfree(cxt->pstore.buf);
fail_clear:
	cxt->pstore.bufsize = 0;
	persistent_ram_free(cxt->mprz);
fail_init_mprz:
fail_init_fprz:
	persistent_ram_free(cxt->cprz);
fail_init_cprz:
	ramoops_free_przs(cxt);
fail_out:
	return err;
}

static int ramoops_remove(struct platform_device *pdev)
{
	struct ramoops_context *cxt = &oops_cxt;

	pstore_unregister(&cxt->pstore);

	kfree(cxt->pstore.buf);
	cxt->pstore.bufsize = 0;

	persistent_ram_free(cxt->mprz);
	persistent_ram_free(cxt->cprz);
	ramoops_free_przs(cxt);

	return 0;
}

static const struct of_device_id dt_match[] = {
	{ .compatible = "ramoops" },
	{}
};

static struct platform_driver ramoops_driver = {
	.probe		= ramoops_probe,
	.remove		= ramoops_remove,
	.driver		= {
		.name		= "ramoops",
		.of_match_table	= dt_match,
	},
};

static inline void ramoops_unregister_dummy(void)
{
	platform_device_unregister(dummy);
	dummy = NULL;
}

static void __init ramoops_register_dummy(void)
{
	struct ramoops_platform_data pdata;

	/*
	 * Prepare a dummy platform data structure to carry the module
	 * parameters. If mem_size isn't set, then there are no module
	 * parameters, and we can skip this.
	 */
	if (!mem_size)
		return;

	pr_info("using module parameters\n");

	memset(&pdata, 0, sizeof(pdata));
	pdata.mem_size = mem_size;
	pdata.mem_address = mem_address;
	pdata.mem_type = mem_type;
	pdata.record_size = record_size;
	pdata.console_size = ramoops_console_size;
	pdata.ftrace_size = ramoops_ftrace_size;
	pdata.pmsg_size = ramoops_pmsg_size;
	/* If "max_reason" is set, its value has priority over "dump_oops". */
	if (ramoops_max_reason >= 0)
		pdata.max_reason = ramoops_max_reason;
	/* Otherwise, if "dump_oops" is set, parse it into "max_reason". */
	else if (ramoops_dump_oops != -1)
		pdata.max_reason = ramoops_dump_oops ? KMSG_DUMP_OOPS
						     : KMSG_DUMP_PANIC;
	/* And if neither are explicitly set, use the default. */
	else
		pdata.max_reason = KMSG_DUMP_OOPS;
	pdata.flags = RAMOOPS_FLAG_FTRACE_PER_CPU;

	/*
	 * For backwards compatibility ramoops.ecc=1 means 16 bytes ECC
	 * (using 1 byte for ECC isn't much of use anyway).
	 */
	pdata.ecc_info.ecc_size = ramoops_ecc == 1 ? 16 : ramoops_ecc;

	dummy = platform_device_register_data(NULL, "ramoops", -1,
			&pdata, sizeof(pdata));
	if (IS_ERR(dummy)) {
		pr_info("could not create platform device: %ld\n",
			PTR_ERR(dummy));
		dummy = NULL;
	}
}

static int __init ramoops_init(void)
{
	int ret;

	ramoops_register_dummy();
	ret = platform_driver_register(&ramoops_driver);
	if (ret != 0)
		ramoops_unregister_dummy();

	return ret;
}
postcore_initcall(ramoops_init);

static void __exit ramoops_exit(void)
{
	platform_driver_unregister(&ramoops_driver);
	ramoops_unregister_dummy();
}
module_exit(ramoops_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marco Stornelli <marco.stornelli@gmail.com>");
MODULE_DESCRIPTION("RAM Oops/Panic logger/driver");