summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/smp.c
blob: 426409e0d071342a58007995b7747d3d22428ea3 (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
// SPDX-License-Identifier: GPL-2.0-only
/*
 * SMP initialisation and IPI support
 * Based on arch/arm/kernel/smp.c
 *
 * Copyright (C) 2012 ARM Ltd.
 */

#include <linux/acpi.h>
#include <linux/arm_sdei.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched/mm.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task_stack.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/irqchip/arm-gic-v3.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <linux/completion.h>
#include <linux/of.h>
#include <linux/irq_work.h>
#include <linux/kexec.h>

#include <asm/alternative.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/cpu_ops.h>
#include <asm/daifflags.h>
#include <asm/mmu_context.h>
#include <asm/numa.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/smp_plat.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/virt.h>

#define CREATE_TRACE_POINTS
#include <trace/events/ipi.h>

DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
EXPORT_PER_CPU_SYMBOL(cpu_number);

/*
 * as from 2.5, kernels no longer have an init_tasks structure
 * so we need some other way of telling a new secondary core
 * where to place its SVC stack
 */
struct secondary_data secondary_data;
/* Number of CPUs which aren't online, but looping in kernel text. */
int cpus_stuck_in_kernel;

enum ipi_msg_type {
	IPI_RESCHEDULE,
	IPI_CALL_FUNC,
	IPI_CPU_STOP,
	IPI_CPU_CRASH_STOP,
	IPI_TIMER,
	IPI_IRQ_WORK,
	IPI_WAKEUP
};

#ifdef CONFIG_HOTPLUG_CPU
static int op_cpu_kill(unsigned int cpu);
#else
static inline int op_cpu_kill(unsigned int cpu)
{
	return -ENOSYS;
}
#endif


/*
 * Boot a secondary CPU, and assign it the specified idle task.
 * This also gives us the initial stack to use for this CPU.
 */
static int boot_secondary(unsigned int cpu, struct task_struct *idle)
{
	if (cpu_ops[cpu]->cpu_boot)
		return cpu_ops[cpu]->cpu_boot(cpu);

	return -EOPNOTSUPP;
}

static DECLARE_COMPLETION(cpu_running);

int __cpu_up(unsigned int cpu, struct task_struct *idle)
{
	int ret;
	long status;

	/*
	 * We need to tell the secondary core where to find its stack and the
	 * page tables.
	 */
	secondary_data.task = idle;
	secondary_data.stack = task_stack_page(idle) + THREAD_SIZE;
	update_cpu_boot_status(CPU_MMU_OFF);
	__flush_dcache_area(&secondary_data, sizeof(secondary_data));

	/*
	 * Now bring the CPU into our world.
	 */
	ret = boot_secondary(cpu, idle);
	if (ret == 0) {
		/*
		 * CPU was successfully started, wait for it to come online or
		 * time out.
		 */
		wait_for_completion_timeout(&cpu_running,
					    msecs_to_jiffies(5000));

		if (!cpu_online(cpu)) {
			pr_crit("CPU%u: failed to come online\n", cpu);
			ret = -EIO;
		}
	} else {
		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
		return ret;
	}

	secondary_data.task = NULL;
	secondary_data.stack = NULL;
	__flush_dcache_area(&secondary_data, sizeof(secondary_data));
	status = READ_ONCE(secondary_data.status);
	if (ret && status) {

		if (status == CPU_MMU_OFF)
			status = READ_ONCE(__early_cpu_boot_status);

		switch (status & CPU_BOOT_STATUS_MASK) {
		default:
			pr_err("CPU%u: failed in unknown state : 0x%lx\n",
					cpu, status);
			cpus_stuck_in_kernel++;
			break;
		case CPU_KILL_ME:
			if (!op_cpu_kill(cpu)) {
				pr_crit("CPU%u: died during early boot\n", cpu);
				break;
			}
			pr_crit("CPU%u: may not have shut down cleanly\n", cpu);
			/* Fall through */
		case CPU_STUCK_IN_KERNEL:
			pr_crit("CPU%u: is stuck in kernel\n", cpu);
			if (status & CPU_STUCK_REASON_52_BIT_VA)
				pr_crit("CPU%u: does not support 52-bit VAs\n", cpu);
			if (status & CPU_STUCK_REASON_NO_GRAN)
				pr_crit("CPU%u: does not support %luK granule \n", cpu, PAGE_SIZE / SZ_1K);
			cpus_stuck_in_kernel++;
			break;
		case CPU_PANIC_KERNEL:
			panic("CPU%u detected unsupported configuration\n", cpu);
		}
	}

	return ret;
}

static void init_gic_priority_masking(void)
{
	u32 cpuflags;

	if (WARN_ON(!gic_enable_sre()))
		return;

	cpuflags = read_sysreg(daif);

	WARN_ON(!(cpuflags & PSR_I_BIT));

	gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET);
}

/*
 * This is the secondary CPU boot entry.  We're using this CPUs
 * idle thread stack, but a set of temporary page tables.
 */
asmlinkage notrace void secondary_start_kernel(void)
{
	u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK;
	struct mm_struct *mm = &init_mm;
	unsigned int cpu;

	cpu = task_cpu(current);
	set_my_cpu_offset(per_cpu_offset(cpu));

	/*
	 * All kernel threads share the same mm context; grab a
	 * reference and switch to it.
	 */
	mmgrab(mm);
	current->active_mm = mm;

	/*
	 * TTBR0 is only used for the identity mapping at this stage. Make it
	 * point to zero page to avoid speculatively fetching new entries.
	 */
	cpu_uninstall_idmap();

	if (system_uses_irq_prio_masking())
		init_gic_priority_masking();

	rcu_cpu_starting(cpu);
	preempt_disable();
	trace_hardirqs_off();

	/*
	 * If the system has established the capabilities, make sure
	 * this CPU ticks all of those. If it doesn't, the CPU will
	 * fail to come online.
	 */
	check_local_cpu_capabilities();

	if (cpu_ops[cpu]->cpu_postboot)
		cpu_ops[cpu]->cpu_postboot();

	/*
	 * Log the CPU info before it is marked online and might get read.
	 */
	cpuinfo_store_cpu();

	/*
	 * Enable GIC and timers.
	 */
	notify_cpu_starting(cpu);

	store_cpu_topology(cpu);
	numa_add_cpu(cpu);

	/*
	 * OK, now it's safe to let the boot CPU continue.  Wait for
	 * the CPU migration code to notice that the CPU is online
	 * before we continue.
	 */
	pr_info("CPU%u: Booted secondary processor 0x%010lx [0x%08x]\n",
					 cpu, (unsigned long)mpidr,
					 read_cpuid_id());
	update_cpu_boot_status(CPU_BOOT_SUCCESS);
	set_cpu_online(cpu, true);
	complete(&cpu_running);

	local_daif_restore(DAIF_PROCCTX);

	/*
	 * OK, it's off to the idle thread for us
	 */
	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}

#ifdef CONFIG_HOTPLUG_CPU
static int op_cpu_disable(unsigned int cpu)
{
	/*
	 * If we don't have a cpu_die method, abort before we reach the point
	 * of no return. CPU0 may not have an cpu_ops, so test for it.
	 */
	if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
		return -EOPNOTSUPP;

	/*
	 * We may need to abort a hot unplug for some other mechanism-specific
	 * reason.
	 */
	if (cpu_ops[cpu]->cpu_disable)
		return cpu_ops[cpu]->cpu_disable(cpu);

	return 0;
}

/*
 * __cpu_disable runs on the processor to be shutdown.
 */
int __cpu_disable(void)
{
	unsigned int cpu = smp_processor_id();
	int ret;

	ret = op_cpu_disable(cpu);
	if (ret)
		return ret;

	remove_cpu_topology(cpu);
	numa_remove_cpu(cpu);

	/*
	 * Take this CPU offline.  Once we clear this, we can't return,
	 * and we must not schedule until we're ready to give up the cpu.
	 */
	set_cpu_online(cpu, false);

	/*
	 * OK - migrate IRQs away from this CPU
	 */
	irq_migrate_all_off_this_cpu();

	return 0;
}

static int op_cpu_kill(unsigned int cpu)
{
	/*
	 * If we have no means of synchronising with the dying CPU, then assume
	 * that it is really dead. We can only wait for an arbitrary length of
	 * time and hope that it's dead, so let's skip the wait and just hope.
	 */
	if (!cpu_ops[cpu]->cpu_kill)
		return 0;

	return cpu_ops[cpu]->cpu_kill(cpu);
}

/*
 * called on the thread which is asking for a CPU to be shutdown -
 * waits until shutdown has completed, or it is timed out.
 */
void __cpu_die(unsigned int cpu)
{
	int err;

	if (!cpu_wait_death(cpu, 5)) {
		pr_crit("CPU%u: cpu didn't die\n", cpu);
		return;
	}
	pr_notice("CPU%u: shutdown\n", cpu);

	/*
	 * Now that the dying CPU is beyond the point of no return w.r.t.
	 * in-kernel synchronisation, try to get the firwmare to help us to
	 * verify that it has really left the kernel before we consider
	 * clobbering anything it might still be using.
	 */
	err = op_cpu_kill(cpu);
	if (err)
		pr_warn("CPU%d may not have shut down cleanly: %d\n",
			cpu, err);
}

/*
 * Called from the idle thread for the CPU which has been shutdown.
 *
 */
void cpu_die(void)
{
	unsigned int cpu = smp_processor_id();

	idle_task_exit();

	local_daif_mask();

	/* Tell __cpu_die() that this CPU is now safe to dispose of */
	(void)cpu_report_death();

	/*
	 * Actually shutdown the CPU. This must never fail. The specific hotplug
	 * mechanism must perform all required cache maintenance to ensure that
	 * no dirty lines are lost in the process of shutting down the CPU.
	 */
	cpu_ops[cpu]->cpu_die(cpu);

	BUG();
}
#endif

/*
 * Kill the calling secondary CPU, early in bringup before it is turned
 * online.
 */
void cpu_die_early(void)
{
	int cpu = smp_processor_id();

	pr_crit("CPU%d: will not boot\n", cpu);

	/* Mark this CPU absent */
	set_cpu_present(cpu, 0);

#ifdef CONFIG_HOTPLUG_CPU
	update_cpu_boot_status(CPU_KILL_ME);
	/* Check if we can park ourselves */
	if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_die)
		cpu_ops[cpu]->cpu_die(cpu);
#endif
	update_cpu_boot_status(CPU_STUCK_IN_KERNEL);

	cpu_park_loop();
}

static void __init hyp_mode_check(void)
{
	if (is_hyp_mode_available())
		pr_info("CPU: All CPU(s) started at EL2\n");
	else if (is_hyp_mode_mismatched())
		WARN_TAINT(1, TAINT_CPU_OUT_OF_SPEC,
			   "CPU: CPUs started in inconsistent modes");
	else
		pr_info("CPU: All CPU(s) started at EL1\n");
}

void __init smp_cpus_done(unsigned int max_cpus)
{
	pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
	setup_cpu_features();
	hyp_mode_check();
	apply_alternatives_all();
	mark_linear_text_alias_ro();
}

void __init smp_prepare_boot_cpu(void)
{
	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
	cpuinfo_store_boot_cpu();

	/*
	 * We now know enough about the boot CPU to apply the
	 * alternatives that cannot wait until interrupt handling
	 * and/or scheduling is enabled.
	 */
	apply_boot_alternatives();

	/* Conditionally switch to GIC PMR for interrupt masking */
	if (system_uses_irq_prio_masking())
		init_gic_priority_masking();
}

static u64 __init of_get_cpu_mpidr(struct device_node *dn)
{
	const __be32 *cell;
	u64 hwid;

	/*
	 * A cpu node with missing "reg" property is
	 * considered invalid to build a cpu_logical_map
	 * entry.
	 */
	cell = of_get_property(dn, "reg", NULL);
	if (!cell) {
		pr_err("%pOF: missing reg property\n", dn);
		return INVALID_HWID;
	}

	hwid = of_read_number(cell, of_n_addr_cells(dn));
	/*
	 * Non affinity bits must be set to 0 in the DT
	 */
	if (hwid & ~MPIDR_HWID_BITMASK) {
		pr_err("%pOF: invalid reg property\n", dn);
		return INVALID_HWID;
	}
	return hwid;
}

/*
 * Duplicate MPIDRs are a recipe for disaster. Scan all initialized
 * entries and check for duplicates. If any is found just ignore the
 * cpu. cpu_logical_map was initialized to INVALID_HWID to avoid
 * matching valid MPIDR values.
 */
static bool __init is_mpidr_duplicate(unsigned int cpu, u64 hwid)
{
	unsigned int i;

	for (i = 1; (i < cpu) && (i < NR_CPUS); i++)
		if (cpu_logical_map(i) == hwid)
			return true;
	return false;
}

/*
 * Initialize cpu operations for a logical cpu and
 * set it in the possible mask on success
 */
static int __init smp_cpu_setup(int cpu)
{
	if (cpu_read_ops(cpu))
		return -ENODEV;

	if (cpu_ops[cpu]->cpu_init(cpu))
		return -ENODEV;

	set_cpu_possible(cpu, true);

	return 0;
}

static bool bootcpu_valid __initdata;
static unsigned int cpu_count = 1;

#ifdef CONFIG_ACPI
static struct acpi_madt_generic_interrupt cpu_madt_gicc[NR_CPUS];

struct acpi_madt_generic_interrupt *acpi_cpu_get_madt_gicc(int cpu)
{
	return &cpu_madt_gicc[cpu];
}

/*
 * acpi_map_gic_cpu_interface - parse processor MADT entry
 *
 * Carry out sanity checks on MADT processor entry and initialize
 * cpu_logical_map on success
 */
static void __init
acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
{
	u64 hwid = processor->arm_mpidr;

	if (!(processor->flags & ACPI_MADT_ENABLED)) {
		pr_debug("skipping disabled CPU entry with 0x%llx MPIDR\n", hwid);
		return;
	}

	if (hwid & ~MPIDR_HWID_BITMASK || hwid == INVALID_HWID) {
		pr_err("skipping CPU entry with invalid MPIDR 0x%llx\n", hwid);
		return;
	}

	if (is_mpidr_duplicate(cpu_count, hwid)) {
		pr_err("duplicate CPU MPIDR 0x%llx in MADT\n", hwid);
		return;
	}

	/* Check if GICC structure of boot CPU is available in the MADT */
	if (cpu_logical_map(0) == hwid) {
		if (bootcpu_valid) {
			pr_err("duplicate boot CPU MPIDR: 0x%llx in MADT\n",
			       hwid);
			return;
		}
		bootcpu_valid = true;
		cpu_madt_gicc[0] = *processor;
		return;
	}

	if (cpu_count >= NR_CPUS)
		return;

	/* map the logical cpu id to cpu MPIDR */
	set_cpu_logical_map(cpu_count, hwid);

	cpu_madt_gicc[cpu_count] = *processor;

	/*
	 * Set-up the ACPI parking protocol cpu entries
	 * while initializing the cpu_logical_map to
	 * avoid parsing MADT entries multiple times for
	 * nothing (ie a valid cpu_logical_map entry should
	 * contain a valid parking protocol data set to
	 * initialize the cpu if the parking protocol is
	 * the only available enable method).
	 */
	acpi_set_mailbox_entry(cpu_count, processor);

	cpu_count++;
}

static int __init
acpi_parse_gic_cpu_interface(union acpi_subtable_headers *header,
			     const unsigned long end)
{
	struct acpi_madt_generic_interrupt *processor;

	processor = (struct acpi_madt_generic_interrupt *)header;
	if (BAD_MADT_GICC_ENTRY(processor, end))
		return -EINVAL;

	acpi_table_print_madt_entry(&header->common);

	acpi_map_gic_cpu_interface(processor);

	return 0;
}

static void __init acpi_parse_and_init_cpus(void)
{
	int i;

	/*
	 * do a walk of MADT to determine how many CPUs
	 * we have including disabled CPUs, and get information
	 * we need for SMP init.
	 */
	acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
				      acpi_parse_gic_cpu_interface, 0);

	/*
	 * In ACPI, SMP and CPU NUMA information is provided in separate
	 * static tables, namely the MADT and the SRAT.
	 *
	 * Thus, it is simpler to first create the cpu logical map through
	 * an MADT walk and then map the logical cpus to their node ids
	 * as separate steps.
	 */
	acpi_map_cpus_to_nodes();

	for (i = 0; i < nr_cpu_ids; i++)
		early_map_cpu_to_node(i, acpi_numa_get_nid(i));
}
#else
#define acpi_parse_and_init_cpus(...)	do { } while (0)
#endif

/*
 * Enumerate the possible CPU set from the device tree and build the
 * cpu logical map array containing MPIDR values related to logical
 * cpus. Assumes that cpu_logical_map(0) has already been initialized.
 */
static void __init of_parse_and_init_cpus(void)
{
	struct device_node *dn;

	for_each_of_cpu_node(dn) {
		u64 hwid = of_get_cpu_mpidr(dn);

		if (hwid == INVALID_HWID)
			goto next;

		if (is_mpidr_duplicate(cpu_count, hwid)) {
			pr_err("%pOF: duplicate cpu reg properties in the DT\n",
				dn);
			goto next;
		}

		/*
		 * The numbering scheme requires that the boot CPU
		 * must be assigned logical id 0. Record it so that
		 * the logical map built from DT is validated and can
		 * be used.
		 */
		if (hwid == cpu_logical_map(0)) {
			if (bootcpu_valid) {
				pr_err("%pOF: duplicate boot cpu reg property in DT\n",
					dn);
				goto next;
			}

			bootcpu_valid = true;
			early_map_cpu_to_node(0, of_node_to_nid(dn));

			/*
			 * cpu_logical_map has already been
			 * initialized and the boot cpu doesn't need
			 * the enable-method so continue without
			 * incrementing cpu.
			 */
			continue;
		}

		if (cpu_count >= NR_CPUS)
			goto next;

		pr_debug("cpu logical map 0x%llx\n", hwid);
		set_cpu_logical_map(cpu_count, hwid);

		early_map_cpu_to_node(cpu_count, of_node_to_nid(dn));
next:
		cpu_count++;
	}
}

/*
 * Enumerate the possible CPU set from the device tree or ACPI and build the
 * cpu logical map array containing MPIDR values related to logical
 * cpus. Assumes that cpu_logical_map(0) has already been initialized.
 */
void __init smp_init_cpus(void)
{
	int i;

	if (acpi_disabled)
		of_parse_and_init_cpus();
	else
		acpi_parse_and_init_cpus();

	if (cpu_count > nr_cpu_ids)
		pr_warn("Number of cores (%d) exceeds configured maximum of %u - clipping\n",
			cpu_count, nr_cpu_ids);

	if (!bootcpu_valid) {
		pr_err("missing boot CPU MPIDR, not enabling secondaries\n");
		return;
	}

	/*
	 * We need to set the cpu_logical_map entries before enabling
	 * the cpus so that cpu processor description entries (DT cpu nodes
	 * and ACPI MADT entries) can be retrieved by matching the cpu hwid
	 * with entries in cpu_logical_map while initializing the cpus.
	 * If the cpu set-up fails, invalidate the cpu_logical_map entry.
	 */
	for (i = 1; i < nr_cpu_ids; i++) {
		if (cpu_logical_map(i) != INVALID_HWID) {
			if (smp_cpu_setup(i))
				set_cpu_logical_map(i, INVALID_HWID);
		}
	}
}

void __init smp_prepare_cpus(unsigned int max_cpus)
{
	int err;
	unsigned int cpu;
	unsigned int this_cpu;

	init_cpu_topology();

	this_cpu = smp_processor_id();
	store_cpu_topology(this_cpu);
	numa_store_cpu_info(this_cpu);
	numa_add_cpu(this_cpu);

	/*
	 * If UP is mandated by "nosmp" (which implies "maxcpus=0"), don't set
	 * secondary CPUs present.
	 */
	if (max_cpus == 0)
		return;

	/*
	 * Initialise the present map (which describes the set of CPUs
	 * actually populated at the present time) and release the
	 * secondaries from the bootloader.
	 */
	for_each_possible_cpu(cpu) {

		per_cpu(cpu_number, cpu) = cpu;

		if (cpu == smp_processor_id())
			continue;

		if (!cpu_ops[cpu])
			continue;

		err = cpu_ops[cpu]->cpu_prepare(cpu);
		if (err)
			continue;

		set_cpu_present(cpu, true);
		numa_store_cpu_info(cpu);
	}
}

void (*__smp_cross_call)(const struct cpumask *, unsigned int);

void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
{
	__smp_cross_call = fn;
}

static const char *ipi_types[NR_IPI] __tracepoint_string = {
#define S(x,s)	[x] = s
	S(IPI_RESCHEDULE, "Rescheduling interrupts"),
	S(IPI_CALL_FUNC, "Function call interrupts"),
	S(IPI_CPU_STOP, "CPU stop interrupts"),
	S(IPI_CPU_CRASH_STOP, "CPU stop (for crash dump) interrupts"),
	S(IPI_TIMER, "Timer broadcast interrupts"),
	S(IPI_IRQ_WORK, "IRQ work interrupts"),
	S(IPI_WAKEUP, "CPU wake-up interrupts"),
};

static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
{
	trace_ipi_raise(target, ipi_types[ipinr]);
	__smp_cross_call(target, ipinr);
}

void show_ipi_list(struct seq_file *p, int prec)
{
	unsigned int cpu, i;

	for (i = 0; i < NR_IPI; i++) {
		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
			   prec >= 4 ? " " : "");
		for_each_online_cpu(cpu)
			seq_printf(p, "%10u ",
				   __get_irq_stat(cpu, ipi_irqs[i]));
		seq_printf(p, "      %s\n", ipi_types[i]);
	}
}

u64 smp_irq_stat_cpu(unsigned int cpu)
{
	u64 sum = 0;
	int i;

	for (i = 0; i < NR_IPI; i++)
		sum += __get_irq_stat(cpu, ipi_irqs[i]);

	return sum;
}

void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
	smp_cross_call(mask, IPI_CALL_FUNC);
}

void arch_send_call_function_single_ipi(int cpu)
{
	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
}

#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
{
	smp_cross_call(mask, IPI_WAKEUP);
}
#endif

#ifdef CONFIG_IRQ_WORK
void arch_irq_work_raise(void)
{
	if (__smp_cross_call)
		smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
}
#endif

static void local_cpu_stop(void)
{
	set_cpu_online(smp_processor_id(), false);

	local_daif_mask();
	sdei_mask_local_cpu();
	cpu_park_loop();
}

/*
 * We need to implement panic_smp_self_stop() for parallel panic() calls, so
 * that cpu_online_mask gets correctly updated and smp_send_stop() can skip
 * CPUs that have already stopped themselves.
 */
void panic_smp_self_stop(void)
{
	local_cpu_stop();
}

#ifdef CONFIG_KEXEC_CORE
static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
#endif

static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
{
#ifdef CONFIG_KEXEC_CORE
	crash_save_cpu(regs, cpu);

	atomic_dec(&waiting_for_crash_ipi);

	local_irq_disable();
	sdei_mask_local_cpu();

#ifdef CONFIG_HOTPLUG_CPU
	if (cpu_ops[cpu]->cpu_die)
		cpu_ops[cpu]->cpu_die(cpu);
#endif

	/* just in case */
	cpu_park_loop();
#endif
}

/*
 * Main handler for inter-processor interrupts
 */
void handle_IPI(int ipinr, struct pt_regs *regs)
{
	unsigned int cpu = smp_processor_id();
	struct pt_regs *old_regs = set_irq_regs(regs);

	if ((unsigned)ipinr < NR_IPI) {
		trace_ipi_entry_rcuidle(ipi_types[ipinr]);
		__inc_irq_stat(cpu, ipi_irqs[ipinr]);
	}

	switch (ipinr) {
	case IPI_RESCHEDULE:
		scheduler_ipi();
		break;

	case IPI_CALL_FUNC:
		irq_enter();
		generic_smp_call_function_interrupt();
		irq_exit();
		break;

	case IPI_CPU_STOP:
		irq_enter();
		local_cpu_stop();
		irq_exit();
		break;

	case IPI_CPU_CRASH_STOP:
		if (IS_ENABLED(CONFIG_KEXEC_CORE)) {
			irq_enter();
			ipi_cpu_crash_stop(cpu, regs);

			unreachable();
		}
		break;

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
	case IPI_TIMER:
		irq_enter();
		tick_receive_broadcast();
		irq_exit();
		break;
#endif

#ifdef CONFIG_IRQ_WORK
	case IPI_IRQ_WORK:
		irq_enter();
		irq_work_run();
		irq_exit();
		break;
#endif

#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
	case IPI_WAKEUP:
		WARN_ONCE(!acpi_parking_protocol_valid(cpu),
			  "CPU%u: Wake-up IPI outside the ACPI parking protocol\n",
			  cpu);
		break;
#endif

	default:
		pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
		break;
	}

	if ((unsigned)ipinr < NR_IPI)
		trace_ipi_exit_rcuidle(ipi_types[ipinr]);
	set_irq_regs(old_regs);
}

void smp_send_reschedule(int cpu)
{
	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}

#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void tick_broadcast(const struct cpumask *mask)
{
	smp_cross_call(mask, IPI_TIMER);
}
#endif

/*
 * The number of CPUs online, not counting this CPU (which may not be
 * fully online and so not counted in num_online_cpus()).
 */
static inline unsigned int num_other_online_cpus(void)
{
	unsigned int this_cpu_online = cpu_online(smp_processor_id());

	return num_online_cpus() - this_cpu_online;
}

void smp_send_stop(void)
{
	unsigned long timeout;

	if (num_other_online_cpus()) {
		cpumask_t mask;

		cpumask_copy(&mask, cpu_online_mask);
		cpumask_clear_cpu(smp_processor_id(), &mask);

		if (system_state <= SYSTEM_RUNNING)
			pr_crit("SMP: stopping secondary CPUs\n");
		smp_cross_call(&mask, IPI_CPU_STOP);
	}

	/* Wait up to one second for other CPUs to stop */
	timeout = USEC_PER_SEC;
	while (num_other_online_cpus() && timeout--)
		udelay(1);

	if (num_other_online_cpus())
		pr_warning("SMP: failed to stop secondary CPUs %*pbl\n",
			   cpumask_pr_args(cpu_online_mask));

	sdei_mask_local_cpu();
}

#ifdef CONFIG_KEXEC_CORE
void crash_smp_send_stop(void)
{
	static int cpus_stopped;
	cpumask_t mask;
	unsigned long timeout;

	/*
	 * This function can be called twice in panic path, but obviously
	 * we execute this only once.
	 */
	if (cpus_stopped)
		return;

	cpus_stopped = 1;

	/*
	 * If this cpu is the only one alive at this point in time, online or
	 * not, there are no stop messages to be sent around, so just back out.
	 */
	if (num_other_online_cpus() == 0) {
		sdei_mask_local_cpu();
		return;
	}

	cpumask_copy(&mask, cpu_online_mask);
	cpumask_clear_cpu(smp_processor_id(), &mask);

	atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());

	pr_crit("SMP: stopping secondary CPUs\n");
	smp_cross_call(&mask, IPI_CPU_CRASH_STOP);

	/* Wait up to one second for other CPUs to stop */
	timeout = USEC_PER_SEC;
	while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
		udelay(1);

	if (atomic_read(&waiting_for_crash_ipi) > 0)
		pr_warning("SMP: failed to stop secondary CPUs %*pbl\n",
			   cpumask_pr_args(&mask));

	sdei_mask_local_cpu();
}

bool smp_crash_stop_failed(void)
{
	return (atomic_read(&waiting_for_crash_ipi) > 0);
}
#endif

/*
 * not supported here
 */
int setup_profiling_timer(unsigned int multiplier)
{
	return -EINVAL;
}

static bool have_cpu_die(void)
{
#ifdef CONFIG_HOTPLUG_CPU
	int any_cpu = raw_smp_processor_id();

	if (cpu_ops[any_cpu] && cpu_ops[any_cpu]->cpu_die)
		return true;
#endif
	return false;
}

bool cpus_are_stuck_in_kernel(void)
{
	bool smp_spin_tables = (num_possible_cpus() > 1 && !have_cpu_die());

	return !!cpus_stuck_in_kernel || smp_spin_tables;
}