summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/arm_sdei.c
blob: 9cd70d1a562218e4ac3bbc3f3f88f1ae693eab1c (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
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2017 Arm Ltd.
#define pr_fmt(fmt) "sdei: " fmt

#include <acpi/ghes.h>
#include <linux/acpi.h>
#include <linux/arm_sdei.h>
#include <linux/arm-smccc.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/compiler.h>
#include <linux/cpuhotplug.h>
#include <linux/cpu.h>
#include <linux/cpu_pm.h>
#include <linux/errno.h>
#include <linux/hardirq.h>
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/kvm_host.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/percpu.h>
#include <linux/platform_device.h>
#include <linux/pm.h>
#include <linux/ptrace.h>
#include <linux/preempt.h>
#include <linux/reboot.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>

/*
 * The call to use to reach the firmware.
 */
static asmlinkage void (*sdei_firmware_call)(unsigned long function_id,
		      unsigned long arg0, unsigned long arg1,
		      unsigned long arg2, unsigned long arg3,
		      unsigned long arg4, struct arm_smccc_res *res);

/* entry point from firmware to arch asm code */
static unsigned long sdei_entry_point;

struct sdei_event {
	/* These three are protected by the sdei_list_lock */
	struct list_head	list;
	bool			reregister;
	bool			reenable;

	u32			event_num;
	u8			type;
	u8			priority;

	/* This pointer is handed to firmware as the event argument. */
	union {
		/* Shared events */
		struct sdei_registered_event *registered;

		/* CPU private events */
		struct sdei_registered_event __percpu *private_registered;
	};
};

/* Take the mutex for any API call or modification. Take the mutex first. */
static DEFINE_MUTEX(sdei_events_lock);

/* and then hold this when modifying the list */
static DEFINE_SPINLOCK(sdei_list_lock);
static LIST_HEAD(sdei_list);

/* Private events are registered/enabled via IPI passing one of these */
struct sdei_crosscall_args {
	struct sdei_event *event;
	atomic_t errors;
	int first_error;
};

#define CROSSCALL_INIT(arg, event)	(arg.event = event, \
					 arg.first_error = 0, \
					 atomic_set(&arg.errors, 0))

static inline int sdei_do_cross_call(void *fn, struct sdei_event * event)
{
	struct sdei_crosscall_args arg;

	CROSSCALL_INIT(arg, event);
	on_each_cpu(fn, &arg, true);

	return arg.first_error;
}

static inline void
sdei_cross_call_return(struct sdei_crosscall_args *arg, int err)
{
	if (err && (atomic_inc_return(&arg->errors) == 1))
		arg->first_error = err;
}

static int sdei_to_linux_errno(unsigned long sdei_err)
{
	switch (sdei_err) {
	case SDEI_NOT_SUPPORTED:
		return -EOPNOTSUPP;
	case SDEI_INVALID_PARAMETERS:
		return -EINVAL;
	case SDEI_DENIED:
		return -EPERM;
	case SDEI_PENDING:
		return -EINPROGRESS;
	case SDEI_OUT_OF_RESOURCE:
		return -ENOMEM;
	}

	/* Not an error value ... */
	return sdei_err;
}

/*
 * If x0 is any of these values, then the call failed, use sdei_to_linux_errno()
 * to translate.
 */
static int sdei_is_err(struct arm_smccc_res *res)
{
	switch (res->a0) {
	case SDEI_NOT_SUPPORTED:
	case SDEI_INVALID_PARAMETERS:
	case SDEI_DENIED:
	case SDEI_PENDING:
	case SDEI_OUT_OF_RESOURCE:
		return true;
	}

	return false;
}

static int invoke_sdei_fn(unsigned long function_id, unsigned long arg0,
			  unsigned long arg1, unsigned long arg2,
			  unsigned long arg3, unsigned long arg4,
			  u64 *result)
{
	int err = 0;
	struct arm_smccc_res res;

	if (sdei_firmware_call) {
		sdei_firmware_call(function_id, arg0, arg1, arg2, arg3, arg4,
				   &res);
		if (sdei_is_err(&res))
			err = sdei_to_linux_errno(res.a0);
	} else {
		/*
		 * !sdei_firmware_call means we failed to probe or called
		 * sdei_mark_interface_broken(). -EIO is not an error returned
		 * by sdei_to_linux_errno() and is used to suppress messages
		 * from this driver.
		 */
		err = -EIO;
		res.a0 = SDEI_NOT_SUPPORTED;
	}

	if (result)
		*result = res.a0;

	return err;
}
NOKPROBE_SYMBOL(invoke_sdei_fn);

static struct sdei_event *sdei_event_find(u32 event_num)
{
	struct sdei_event *e, *found = NULL;

	lockdep_assert_held(&sdei_events_lock);

	spin_lock(&sdei_list_lock);
	list_for_each_entry(e, &sdei_list, list) {
		if (e->event_num == event_num) {
			found = e;
			break;
		}
	}
	spin_unlock(&sdei_list_lock);

	return found;
}

int sdei_api_event_context(u32 query, u64 *result)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_CONTEXT, query, 0, 0, 0, 0,
			      result);
}
NOKPROBE_SYMBOL(sdei_api_event_context);

static int sdei_api_event_get_info(u32 event, u32 info, u64 *result)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_GET_INFO, event, info, 0,
			      0, 0, result);
}

static struct sdei_event *sdei_event_create(u32 event_num,
					    sdei_event_callback *cb,
					    void *cb_arg)
{
	int err;
	u64 result;
	struct sdei_event *event;
	struct sdei_registered_event *reg;

	lockdep_assert_held(&sdei_events_lock);

	event = kzalloc(sizeof(*event), GFP_KERNEL);
	if (!event)
		return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(&event->list);
	event->event_num = event_num;

	err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_PRIORITY,
				      &result);
	if (err) {
		kfree(event);
		return ERR_PTR(err);
	}
	event->priority = result;

	err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_TYPE,
				      &result);
	if (err) {
		kfree(event);
		return ERR_PTR(err);
	}
	event->type = result;

	if (event->type == SDEI_EVENT_TYPE_SHARED) {
		reg = kzalloc(sizeof(*reg), GFP_KERNEL);
		if (!reg) {
			kfree(event);
			return ERR_PTR(-ENOMEM);
		}

		reg->event_num = event_num;
		reg->priority = event->priority;

		reg->callback = cb;
		reg->callback_arg = cb_arg;
		event->registered = reg;
	} else {
		int cpu;
		struct sdei_registered_event __percpu *regs;

		regs = alloc_percpu(struct sdei_registered_event);
		if (!regs) {
			kfree(event);
			return ERR_PTR(-ENOMEM);
		}

		for_each_possible_cpu(cpu) {
			reg = per_cpu_ptr(regs, cpu);

			reg->event_num = event->event_num;
			reg->priority = event->priority;
			reg->callback = cb;
			reg->callback_arg = cb_arg;
		}

		event->private_registered = regs;
	}

	if (sdei_event_find(event_num)) {
		kfree(event->registered);
		kfree(event);
		event = ERR_PTR(-EBUSY);
	} else {
		spin_lock(&sdei_list_lock);
		list_add(&event->list, &sdei_list);
		spin_unlock(&sdei_list_lock);
	}

	return event;
}

static void sdei_event_destroy(struct sdei_event *event)
{
	lockdep_assert_held(&sdei_events_lock);

	spin_lock(&sdei_list_lock);
	list_del(&event->list);
	spin_unlock(&sdei_list_lock);

	if (event->type == SDEI_EVENT_TYPE_SHARED)
		kfree(event->registered);
	else
		free_percpu(event->private_registered);

	kfree(event);
}

static int sdei_api_get_version(u64 *version)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_VERSION, 0, 0, 0, 0, 0, version);
}

int sdei_mask_local_cpu(void)
{
	int err;

	WARN_ON_ONCE(preemptible());

	err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_MASK, 0, 0, 0, 0, 0, NULL);
	if (err && err != -EIO) {
		pr_warn_once("failed to mask CPU[%u]: %d\n",
			      smp_processor_id(), err);
		return err;
	}

	return 0;
}

static void _ipi_mask_cpu(void *ignored)
{
	sdei_mask_local_cpu();
}

int sdei_unmask_local_cpu(void)
{
	int err;

	WARN_ON_ONCE(preemptible());

	err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PE_UNMASK, 0, 0, 0, 0, 0, NULL);
	if (err && err != -EIO) {
		pr_warn_once("failed to unmask CPU[%u]: %d\n",
			     smp_processor_id(), err);
		return err;
	}

	return 0;
}

static void _ipi_unmask_cpu(void *ignored)
{
	sdei_unmask_local_cpu();
}

static void _ipi_private_reset(void *ignored)
{
	int err;

	err = invoke_sdei_fn(SDEI_1_0_FN_SDEI_PRIVATE_RESET, 0, 0, 0, 0, 0,
			     NULL);
	if (err && err != -EIO)
		pr_warn_once("failed to reset CPU[%u]: %d\n",
			     smp_processor_id(), err);
}

static int sdei_api_shared_reset(void)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_SHARED_RESET, 0, 0, 0, 0, 0,
			      NULL);
}

static void sdei_mark_interface_broken(void)
{
	pr_err("disabling SDEI firmware interface\n");
	on_each_cpu(&_ipi_mask_cpu, NULL, true);
	sdei_firmware_call = NULL;
}

static int sdei_platform_reset(void)
{
	int err;

	on_each_cpu(&_ipi_private_reset, NULL, true);
	err = sdei_api_shared_reset();
	if (err) {
		pr_err("Failed to reset platform: %d\n", err);
		sdei_mark_interface_broken();
	}

	return err;
}

static int sdei_api_event_enable(u32 event_num)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_ENABLE, event_num, 0, 0, 0,
			      0, NULL);
}

/* Called directly by the hotplug callbacks */
static void _local_event_enable(void *data)
{
	int err;
	struct sdei_crosscall_args *arg = data;

	WARN_ON_ONCE(preemptible());

	err = sdei_api_event_enable(arg->event->event_num);

	sdei_cross_call_return(arg, err);
}

int sdei_event_enable(u32 event_num)
{
	int err = -EINVAL;
	struct sdei_event *event;

	mutex_lock(&sdei_events_lock);
	event = sdei_event_find(event_num);
	if (!event) {
		mutex_unlock(&sdei_events_lock);
		return -ENOENT;
	}

	spin_lock(&sdei_list_lock);
	event->reenable = true;
	spin_unlock(&sdei_list_lock);

	if (event->type == SDEI_EVENT_TYPE_SHARED)
		err = sdei_api_event_enable(event->event_num);
	else
		err = sdei_do_cross_call(_local_event_enable, event);
	mutex_unlock(&sdei_events_lock);

	return err;
}
EXPORT_SYMBOL(sdei_event_enable);

static int sdei_api_event_disable(u32 event_num)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_DISABLE, event_num, 0, 0,
			      0, 0, NULL);
}

static void _ipi_event_disable(void *data)
{
	int err;
	struct sdei_crosscall_args *arg = data;

	err = sdei_api_event_disable(arg->event->event_num);

	sdei_cross_call_return(arg, err);
}

int sdei_event_disable(u32 event_num)
{
	int err = -EINVAL;
	struct sdei_event *event;

	mutex_lock(&sdei_events_lock);
	event = sdei_event_find(event_num);
	if (!event) {
		mutex_unlock(&sdei_events_lock);
		return -ENOENT;
	}

	spin_lock(&sdei_list_lock);
	event->reenable = false;
	spin_unlock(&sdei_list_lock);

	if (event->type == SDEI_EVENT_TYPE_SHARED)
		err = sdei_api_event_disable(event->event_num);
	else
		err = sdei_do_cross_call(_ipi_event_disable, event);
	mutex_unlock(&sdei_events_lock);

	return err;
}
EXPORT_SYMBOL(sdei_event_disable);

static int sdei_api_event_unregister(u32 event_num)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_UNREGISTER, event_num, 0,
			      0, 0, 0, NULL);
}

/* Called directly by the hotplug callbacks */
static void _local_event_unregister(void *data)
{
	int err;
	struct sdei_crosscall_args *arg = data;

	WARN_ON_ONCE(preemptible());

	err = sdei_api_event_unregister(arg->event->event_num);

	sdei_cross_call_return(arg, err);
}

static int _sdei_event_unregister(struct sdei_event *event)
{
	lockdep_assert_held(&sdei_events_lock);

	spin_lock(&sdei_list_lock);
	event->reregister = false;
	event->reenable = false;
	spin_unlock(&sdei_list_lock);

	if (event->type == SDEI_EVENT_TYPE_SHARED)
		return sdei_api_event_unregister(event->event_num);

	return sdei_do_cross_call(_local_event_unregister, event);
}

int sdei_event_unregister(u32 event_num)
{
	int err;
	struct sdei_event *event;

	WARN_ON(in_nmi());

	mutex_lock(&sdei_events_lock);
	event = sdei_event_find(event_num);
	do {
		if (!event) {
			pr_warn("Event %u not registered\n", event_num);
			err = -ENOENT;
			break;
		}

		err = _sdei_event_unregister(event);
		if (err)
			break;

		sdei_event_destroy(event);
	} while (0);
	mutex_unlock(&sdei_events_lock);

	return err;
}
EXPORT_SYMBOL(sdei_event_unregister);

/*
 * unregister events, but don't destroy them as they are re-registered by
 * sdei_reregister_shared().
 */
static int sdei_unregister_shared(void)
{
	int err = 0;
	struct sdei_event *event;

	mutex_lock(&sdei_events_lock);
	spin_lock(&sdei_list_lock);
	list_for_each_entry(event, &sdei_list, list) {
		if (event->type != SDEI_EVENT_TYPE_SHARED)
			continue;

		err = _sdei_event_unregister(event);
		if (err)
			break;
	}
	spin_unlock(&sdei_list_lock);
	mutex_unlock(&sdei_events_lock);

	return err;
}

static int sdei_api_event_register(u32 event_num, unsigned long entry_point,
				   void *arg, u64 flags, u64 affinity)
{
	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_REGISTER, event_num,
			      (unsigned long)entry_point, (unsigned long)arg,
			      flags, affinity, NULL);
}

/* Called directly by the hotplug callbacks */
static void _local_event_register(void *data)
{
	int err;
	struct sdei_registered_event *reg;
	struct sdei_crosscall_args *arg = data;

	WARN_ON(preemptible());

	reg = per_cpu_ptr(arg->event->private_registered, smp_processor_id());
	err = sdei_api_event_register(arg->event->event_num, sdei_entry_point,
				      reg, 0, 0);

	sdei_cross_call_return(arg, err);
}

static int _sdei_event_register(struct sdei_event *event)
{
	int err;

	lockdep_assert_held(&sdei_events_lock);

	spin_lock(&sdei_list_lock);
	event->reregister = true;
	spin_unlock(&sdei_list_lock);

	if (event->type == SDEI_EVENT_TYPE_SHARED)
		return sdei_api_event_register(event->event_num,
					       sdei_entry_point,
					       event->registered,
					       SDEI_EVENT_REGISTER_RM_ANY, 0);


	err = sdei_do_cross_call(_local_event_register, event);
	if (err) {
		spin_lock(&sdei_list_lock);
		event->reregister = false;
		event->reenable = false;
		spin_unlock(&sdei_list_lock);

		sdei_do_cross_call(_local_event_unregister, event);
	}

	return err;
}

int sdei_event_register(u32 event_num, sdei_event_callback *cb, void *arg)
{
	int err;
	struct sdei_event *event;

	WARN_ON(in_nmi());

	mutex_lock(&sdei_events_lock);
	do {
		if (sdei_event_find(event_num)) {
			pr_warn("Event %u already registered\n", event_num);
			err = -EBUSY;
			break;
		}

		event = sdei_event_create(event_num, cb, arg);
		if (IS_ERR(event)) {
			err = PTR_ERR(event);
			pr_warn("Failed to create event %u: %d\n", event_num,
				err);
			break;
		}

		err = _sdei_event_register(event);
		if (err) {
			sdei_event_destroy(event);
			pr_warn("Failed to register event %u: %d\n", event_num,
				err);
		}
	} while (0);
	mutex_unlock(&sdei_events_lock);

	return err;
}
EXPORT_SYMBOL(sdei_event_register);

static int sdei_reregister_event(struct sdei_event *event)
{
	int err;

	lockdep_assert_held(&sdei_events_lock);

	err = _sdei_event_register(event);
	if (err) {
		pr_err("Failed to re-register event %u\n", event->event_num);
		sdei_event_destroy(event);
		return err;
	}

	if (event->reenable) {
		if (event->type == SDEI_EVENT_TYPE_SHARED)
			err = sdei_api_event_enable(event->event_num);
		else
			err = sdei_do_cross_call(_local_event_enable, event);
	}

	if (err)
		pr_err("Failed to re-enable event %u\n", event->event_num);

	return err;
}

static int sdei_reregister_shared(void)
{
	int err = 0;
	struct sdei_event *event;

	mutex_lock(&sdei_events_lock);
	spin_lock(&sdei_list_lock);
	list_for_each_entry(event, &sdei_list, list) {
		if (event->type != SDEI_EVENT_TYPE_SHARED)
			continue;

		if (event->reregister) {
			err = sdei_reregister_event(event);
			if (err)
				break;
		}
	}
	spin_unlock(&sdei_list_lock);
	mutex_unlock(&sdei_events_lock);

	return err;
}

static int sdei_cpuhp_down(unsigned int cpu)
{
	struct sdei_event *event;
	struct sdei_crosscall_args arg;

	/* un-register private events */
	spin_lock(&sdei_list_lock);
	list_for_each_entry(event, &sdei_list, list) {
		if (event->type == SDEI_EVENT_TYPE_SHARED)
			continue;

		CROSSCALL_INIT(arg, event);
		/* call the cross-call function locally... */
		_local_event_unregister(&arg);
		if (arg.first_error)
			pr_err("Failed to unregister event %u: %d\n",
			       event->event_num, arg.first_error);
	}
	spin_unlock(&sdei_list_lock);

	return sdei_mask_local_cpu();
}

static int sdei_cpuhp_up(unsigned int cpu)
{
	struct sdei_event *event;
	struct sdei_crosscall_args arg;

	/* re-register/enable private events */
	spin_lock(&sdei_list_lock);
	list_for_each_entry(event, &sdei_list, list) {
		if (event->type == SDEI_EVENT_TYPE_SHARED)
			continue;

		if (event->reregister) {
			CROSSCALL_INIT(arg, event);
			/* call the cross-call function locally... */
			_local_event_register(&arg);
			if (arg.first_error)
				pr_err("Failed to re-register event %u: %d\n",
				       event->event_num, arg.first_error);
		}

		if (event->reenable) {
			CROSSCALL_INIT(arg, event);
			_local_event_enable(&arg);
			if (arg.first_error)
				pr_err("Failed to re-enable event %u: %d\n",
				       event->event_num, arg.first_error);
		}
	}
	spin_unlock(&sdei_list_lock);

	return sdei_unmask_local_cpu();
}

/* When entering idle, mask/unmask events for this cpu */
static int sdei_pm_notifier(struct notifier_block *nb, unsigned long action,
			    void *data)
{
	int rv;

	switch (action) {
	case CPU_PM_ENTER:
		rv = sdei_mask_local_cpu();
		break;
	case CPU_PM_EXIT:
	case CPU_PM_ENTER_FAILED:
		rv = sdei_unmask_local_cpu();
		break;
	default:
		return NOTIFY_DONE;
	}

	if (rv)
		return notifier_from_errno(rv);

	return NOTIFY_OK;
}

static struct notifier_block sdei_pm_nb = {
	.notifier_call = sdei_pm_notifier,
};

static int sdei_device_suspend(struct device *dev)
{
	on_each_cpu(_ipi_mask_cpu, NULL, true);

	return 0;
}

static int sdei_device_resume(struct device *dev)
{
	on_each_cpu(_ipi_unmask_cpu, NULL, true);

	return 0;
}

/*
 * We need all events to be reregistered when we resume from hibernate.
 *
 * The sequence is freeze->thaw. Reboot. freeze->restore. We unregister
 * events during freeze, then re-register and re-enable them during thaw
 * and restore.
 */
static int sdei_device_freeze(struct device *dev)
{
	int err;

	/* unregister private events */
	cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);

	err = sdei_unregister_shared();
	if (err)
		return err;

	return 0;
}

static int sdei_device_thaw(struct device *dev)
{
	int err;

	/* re-register shared events */
	err = sdei_reregister_shared();
	if (err) {
		pr_warn("Failed to re-register shared events...\n");
		sdei_mark_interface_broken();
		return err;
	}

	err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
				&sdei_cpuhp_up, &sdei_cpuhp_down);
	if (err)
		pr_warn("Failed to re-register CPU hotplug notifier...\n");

	return err;
}

static int sdei_device_restore(struct device *dev)
{
	int err;

	err = sdei_platform_reset();
	if (err)
		return err;

	return sdei_device_thaw(dev);
}

static const struct dev_pm_ops sdei_pm_ops = {
	.suspend = sdei_device_suspend,
	.resume = sdei_device_resume,
	.freeze = sdei_device_freeze,
	.thaw = sdei_device_thaw,
	.restore = sdei_device_restore,
};

/*
 * Mask all CPUs and unregister all events on panic, reboot or kexec.
 */
static int sdei_reboot_notifier(struct notifier_block *nb, unsigned long action,
				void *data)
{
	/*
	 * We are going to reset the interface, after this there is no point
	 * doing work when we take CPUs offline.
	 */
	cpuhp_remove_state(CPUHP_AP_ARM_SDEI_STARTING);

	sdei_platform_reset();

	return NOTIFY_OK;
}

static struct notifier_block sdei_reboot_nb = {
	.notifier_call = sdei_reboot_notifier,
};

static void sdei_smccc_smc(unsigned long function_id,
			   unsigned long arg0, unsigned long arg1,
			   unsigned long arg2, unsigned long arg3,
			   unsigned long arg4, struct arm_smccc_res *res)
{
	arm_smccc_smc(function_id, arg0, arg1, arg2, arg3, arg4, 0, 0, res);
}
NOKPROBE_SYMBOL(sdei_smccc_smc);

static void sdei_smccc_hvc(unsigned long function_id,
			   unsigned long arg0, unsigned long arg1,
			   unsigned long arg2, unsigned long arg3,
			   unsigned long arg4, struct arm_smccc_res *res)
{
	arm_smccc_hvc(function_id, arg0, arg1, arg2, arg3, arg4, 0, 0, res);
}
NOKPROBE_SYMBOL(sdei_smccc_hvc);

int sdei_register_ghes(struct ghes *ghes, sdei_event_callback *normal_cb,
		       sdei_event_callback *critical_cb)
{
	int err;
	u64 result;
	u32 event_num;
	sdei_event_callback *cb;

	if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES))
		return -EOPNOTSUPP;

	event_num = ghes->generic->notify.vector;
	if (event_num == 0) {
		/*
		 * Event 0 is reserved by the specification for
		 * SDEI_EVENT_SIGNAL.
		 */
		return -EINVAL;
	}

	err = sdei_api_event_get_info(event_num, SDEI_EVENT_INFO_EV_PRIORITY,
				      &result);
	if (err)
		return err;

	if (result == SDEI_EVENT_PRIORITY_CRITICAL)
		cb = critical_cb;
	else
		cb = normal_cb;

	err = sdei_event_register(event_num, cb, ghes);
	if (!err)
		err = sdei_event_enable(event_num);

	return err;
}

int sdei_unregister_ghes(struct ghes *ghes)
{
	int i;
	int err;
	u32 event_num = ghes->generic->notify.vector;

	might_sleep();

	if (!IS_ENABLED(CONFIG_ACPI_APEI_GHES))
		return -EOPNOTSUPP;

	/*
	 * The event may be running on another CPU. Disable it
	 * to stop new events, then try to unregister a few times.
	 */
	err = sdei_event_disable(event_num);
	if (err)
		return err;

	for (i = 0; i < 3; i++) {
		err = sdei_event_unregister(event_num);
		if (err != -EINPROGRESS)
			break;

		schedule();
	}

	return err;
}

static int sdei_get_conduit(struct platform_device *pdev)
{
	const char *method;
	struct device_node *np = pdev->dev.of_node;

	sdei_firmware_call = NULL;
	if (np) {
		if (of_property_read_string(np, "method", &method)) {
			pr_warn("missing \"method\" property\n");
			return CONDUIT_INVALID;
		}

		if (!strcmp("hvc", method)) {
			sdei_firmware_call = &sdei_smccc_hvc;
			return CONDUIT_HVC;
		} else if (!strcmp("smc", method)) {
			sdei_firmware_call = &sdei_smccc_smc;
			return CONDUIT_SMC;
		}

		pr_warn("invalid \"method\" property: %s\n", method);
	} else if (IS_ENABLED(CONFIG_ACPI) && !acpi_disabled) {
		if (acpi_psci_use_hvc()) {
			sdei_firmware_call = &sdei_smccc_hvc;
			return CONDUIT_HVC;
		} else {
			sdei_firmware_call = &sdei_smccc_smc;
			return CONDUIT_SMC;
		}
	}

	return CONDUIT_INVALID;
}

static int sdei_probe(struct platform_device *pdev)
{
	int err;
	u64 ver = 0;
	int conduit;

	conduit = sdei_get_conduit(pdev);
	if (!sdei_firmware_call)
		return 0;

	err = sdei_api_get_version(&ver);
	if (err == -EOPNOTSUPP)
		pr_err("advertised but not implemented in platform firmware\n");
	if (err) {
		pr_err("Failed to get SDEI version: %d\n", err);
		sdei_mark_interface_broken();
		return err;
	}

	pr_info("SDEIv%d.%d (0x%x) detected in firmware.\n",
		(int)SDEI_VERSION_MAJOR(ver), (int)SDEI_VERSION_MINOR(ver),
		(int)SDEI_VERSION_VENDOR(ver));

	if (SDEI_VERSION_MAJOR(ver) != 1) {
		pr_warn("Conflicting SDEI version detected.\n");
		sdei_mark_interface_broken();
		return -EINVAL;
	}

	err = sdei_platform_reset();
	if (err)
		return err;

	sdei_entry_point = sdei_arch_get_entry_point(conduit);
	if (!sdei_entry_point) {
		/* Not supported due to hardware or boot configuration */
		sdei_mark_interface_broken();
		return 0;
	}

	err = cpu_pm_register_notifier(&sdei_pm_nb);
	if (err) {
		pr_warn("Failed to register CPU PM notifier...\n");
		goto error;
	}

	err = register_reboot_notifier(&sdei_reboot_nb);
	if (err) {
		pr_warn("Failed to register reboot notifier...\n");
		goto remove_cpupm;
	}

	err = cpuhp_setup_state(CPUHP_AP_ARM_SDEI_STARTING, "SDEI",
				&sdei_cpuhp_up, &sdei_cpuhp_down);
	if (err) {
		pr_warn("Failed to register CPU hotplug notifier...\n");
		goto remove_reboot;
	}

	return 0;

remove_reboot:
	unregister_reboot_notifier(&sdei_reboot_nb);

remove_cpupm:
	cpu_pm_unregister_notifier(&sdei_pm_nb);

error:
	sdei_mark_interface_broken();
	return err;
}

static const struct of_device_id sdei_of_match[] = {
	{ .compatible = "arm,sdei-1.0" },
	{}
};

static struct platform_driver sdei_driver = {
	.driver		= {
		.name			= "sdei",
		.pm			= &sdei_pm_ops,
		.of_match_table		= sdei_of_match,
	},
	.probe		= sdei_probe,
};

static bool __init sdei_present_dt(void)
{
	struct device_node *np, *fw_np;

	fw_np = of_find_node_by_name(NULL, "firmware");
	if (!fw_np)
		return false;

	np = of_find_matching_node(fw_np, sdei_of_match);
	if (!np)
		return false;
	of_node_put(np);

	return true;
}

static bool __init sdei_present_acpi(void)
{
	acpi_status status;
	struct platform_device *pdev;
	struct acpi_table_header *sdei_table_header;

	if (acpi_disabled)
		return false;

	status = acpi_get_table(ACPI_SIG_SDEI, 0, &sdei_table_header);
	if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
		const char *msg = acpi_format_exception(status);

		pr_info("Failed to get ACPI:SDEI table, %s\n", msg);
	}
	if (ACPI_FAILURE(status))
		return false;

	pdev = platform_device_register_simple(sdei_driver.driver.name, 0, NULL,
					       0);
	if (IS_ERR(pdev))
		return false;

	return true;
}

static int __init sdei_init(void)
{
	if (sdei_present_dt() || sdei_present_acpi())
		platform_driver_register(&sdei_driver);

	return 0;
}

/*
 * On an ACPI system SDEI needs to be ready before HEST:GHES tries to register
 * its events. ACPI is initialised from a subsys_initcall(), GHES is initialised
 * by device_initcall(). We want to be called in the middle.
 */
subsys_initcall_sync(sdei_init);

int sdei_event_handler(struct pt_regs *regs,
		       struct sdei_registered_event *arg)
{
	int err;
	mm_segment_t orig_addr_limit;
	u32 event_num = arg->event_num;

	orig_addr_limit = get_fs();
	set_fs(USER_DS);

	err = arg->callback(event_num, regs, arg->callback_arg);
	if (err)
		pr_err_ratelimited("event %u on CPU %u failed with error: %d\n",
				   event_num, smp_processor_id(), err);

	set_fs(orig_addr_limit);

	return err;
}
NOKPROBE_SYMBOL(sdei_event_handler);