• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * SMP initialisation and IPI support
3  * Based on arch/arm/kernel/smp.c
4  *
5  * Copyright (C) 2012 ARM Ltd.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
18  */
19 
20 #include <linux/acpi.h>
21 #include <linux/delay.h>
22 #include <linux/init.h>
23 #include <linux/spinlock.h>
24 #include <linux/sched/mm.h>
25 #include <linux/sched/hotplug.h>
26 #include <linux/sched/task_stack.h>
27 #include <linux/interrupt.h>
28 #include <linux/cache.h>
29 #include <linux/profile.h>
30 #include <linux/errno.h>
31 #include <linux/mm.h>
32 #include <linux/err.h>
33 #include <linux/cpu.h>
34 #include <linux/smp.h>
35 #include <linux/seq_file.h>
36 #include <linux/irq.h>
37 #include <linux/percpu.h>
38 #include <linux/clockchips.h>
39 #include <linux/completion.h>
40 #include <linux/of.h>
41 #include <linux/irq_work.h>
42 #include <linux/kexec.h>
43 
44 #include <asm/alternative.h>
45 #include <asm/atomic.h>
46 #include <asm/cacheflush.h>
47 #include <asm/cpu.h>
48 #include <asm/cputype.h>
49 #include <asm/cpu_ops.h>
50 #include <asm/mmu_context.h>
51 #include <asm/numa.h>
52 #include <asm/pgtable.h>
53 #include <asm/pgalloc.h>
54 #include <asm/processor.h>
55 #include <asm/smp_plat.h>
56 #include <asm/sections.h>
57 #include <asm/tlbflush.h>
58 #include <asm/ptrace.h>
59 #include <asm/virt.h>
60 
61 #define CREATE_TRACE_POINTS
62 #include <trace/events/ipi.h>
63 
64 DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
65 EXPORT_PER_CPU_SYMBOL(cpu_number);
66 
67 /*
68  * as from 2.5, kernels no longer have an init_tasks structure
69  * so we need some other way of telling a new secondary core
70  * where to place its SVC stack
71  */
72 struct secondary_data secondary_data;
73 /* Number of CPUs which aren't online, but looping in kernel text. */
74 int cpus_stuck_in_kernel;
75 
76 enum ipi_msg_type {
77 	IPI_RESCHEDULE,
78 	IPI_CALL_FUNC,
79 	IPI_CPU_STOP,
80 	IPI_CPU_CRASH_STOP,
81 	IPI_TIMER,
82 	IPI_IRQ_WORK,
83 	IPI_WAKEUP
84 };
85 
86 #ifdef CONFIG_HOTPLUG_CPU
87 static int op_cpu_kill(unsigned int cpu);
88 #else
op_cpu_kill(unsigned int cpu)89 static inline int op_cpu_kill(unsigned int cpu)
90 {
91 	return -ENOSYS;
92 }
93 #endif
94 
95 
96 /*
97  * Boot a secondary CPU, and assign it the specified idle task.
98  * This also gives us the initial stack to use for this CPU.
99  */
boot_secondary(unsigned int cpu,struct task_struct * idle)100 static int boot_secondary(unsigned int cpu, struct task_struct *idle)
101 {
102 	if (cpu_ops[cpu]->cpu_boot)
103 		return cpu_ops[cpu]->cpu_boot(cpu);
104 
105 	return -EOPNOTSUPP;
106 }
107 
108 static DECLARE_COMPLETION(cpu_running);
109 bool va52mismatch __ro_after_init;
110 
__cpu_up(unsigned int cpu,struct task_struct * idle)111 int __cpu_up(unsigned int cpu, struct task_struct *idle)
112 {
113 	int ret;
114 	long status;
115 
116 	/*
117 	 * We need to tell the secondary core where to find its stack and the
118 	 * page tables.
119 	 */
120 	secondary_data.task = idle;
121 	secondary_data.stack = task_stack_page(idle) + THREAD_SIZE;
122 	update_cpu_boot_status(CPU_MMU_OFF);
123 	__flush_dcache_area(&secondary_data, sizeof(secondary_data));
124 
125 	/*
126 	 * Now bring the CPU into our world.
127 	 */
128 	ret = boot_secondary(cpu, idle);
129 	if (ret == 0) {
130 		/*
131 		 * CPU was successfully started, wait for it to come online or
132 		 * time out.
133 		 */
134 		wait_for_completion_timeout(&cpu_running,
135 					    msecs_to_jiffies(1000));
136 
137 		if (!cpu_online(cpu)) {
138 			pr_crit("CPU%u: failed to come online\n", cpu);
139 
140 			if (IS_ENABLED(CONFIG_ARM64_52BIT_VA) && va52mismatch)
141 				pr_crit("CPU%u: does not support 52-bit VAs\n", cpu);
142 
143 			ret = -EIO;
144 		}
145 	} else {
146 		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
147 		return ret;
148 	}
149 
150 	secondary_data.task = NULL;
151 	secondary_data.stack = NULL;
152 	status = READ_ONCE(secondary_data.status);
153 	if (ret && status) {
154 
155 		if (status == CPU_MMU_OFF)
156 			status = READ_ONCE(__early_cpu_boot_status);
157 
158 		switch (status) {
159 		default:
160 			pr_err("CPU%u: failed in unknown state : 0x%lx\n",
161 					cpu, status);
162 			break;
163 		case CPU_KILL_ME:
164 			if (!op_cpu_kill(cpu)) {
165 				pr_crit("CPU%u: died during early boot\n", cpu);
166 				break;
167 			}
168 			/* Fall through */
169 			pr_crit("CPU%u: may not have shut down cleanly\n", cpu);
170 		case CPU_STUCK_IN_KERNEL:
171 			pr_crit("CPU%u: is stuck in kernel\n", cpu);
172 			cpus_stuck_in_kernel++;
173 			break;
174 		case CPU_PANIC_KERNEL:
175 			panic("CPU%u detected unsupported configuration\n", cpu);
176 		}
177 	}
178 
179 	return ret;
180 }
181 
182 /*
183  * This is the secondary CPU boot entry.  We're using this CPUs
184  * idle thread stack, but a set of temporary page tables.
185  */
secondary_start_kernel(void)186 asmlinkage notrace void secondary_start_kernel(void)
187 {
188 	struct mm_struct *mm = &init_mm;
189 	unsigned int cpu;
190 
191 	cpu = task_cpu(current);
192 	set_my_cpu_offset(per_cpu_offset(cpu));
193 
194 	/*
195 	 * All kernel threads share the same mm context; grab a
196 	 * reference and switch to it.
197 	 */
198 	mmgrab(mm);
199 	current->active_mm = mm;
200 
201 	/*
202 	 * TTBR0 is only used for the identity mapping at this stage. Make it
203 	 * point to zero page to avoid speculatively fetching new entries.
204 	 */
205 	cpu_uninstall_idmap();
206 
207 	preempt_disable();
208 	trace_hardirqs_off();
209 
210 	/*
211 	 * If the system has established the capabilities, make sure
212 	 * this CPU ticks all of those. If it doesn't, the CPU will
213 	 * fail to come online.
214 	 */
215 	check_local_cpu_capabilities();
216 
217 	if (cpu_ops[cpu]->cpu_postboot)
218 		cpu_ops[cpu]->cpu_postboot();
219 
220 	/*
221 	 * Log the CPU info before it is marked online and might get read.
222 	 */
223 	cpuinfo_store_cpu();
224 
225 	/*
226 	 * Enable GIC and timers.
227 	 */
228 	notify_cpu_starting(cpu);
229 
230 	store_cpu_topology(cpu);
231 
232 	/*
233 	 * OK, now it's safe to let the boot CPU continue.  Wait for
234 	 * the CPU migration code to notice that the CPU is online
235 	 * before we continue.
236 	 */
237 	pr_info("CPU%u: Booted secondary processor [%08x]\n",
238 					 cpu, read_cpuid_id());
239 	update_cpu_boot_status(CPU_BOOT_SUCCESS);
240 	set_cpu_online(cpu, true);
241 	complete(&cpu_running);
242 
243 	local_irq_enable();
244 	local_async_enable();
245 
246 	/*
247 	 * OK, it's off to the idle thread for us
248 	 */
249 	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
250 }
251 
252 #ifdef CONFIG_HOTPLUG_CPU
op_cpu_disable(unsigned int cpu)253 static int op_cpu_disable(unsigned int cpu)
254 {
255 	/*
256 	 * If we don't have a cpu_die method, abort before we reach the point
257 	 * of no return. CPU0 may not have an cpu_ops, so test for it.
258 	 */
259 	if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
260 		return -EOPNOTSUPP;
261 
262 	/*
263 	 * We may need to abort a hot unplug for some other mechanism-specific
264 	 * reason.
265 	 */
266 	if (cpu_ops[cpu]->cpu_disable)
267 		return cpu_ops[cpu]->cpu_disable(cpu);
268 
269 	return 0;
270 }
271 
272 /*
273  * __cpu_disable runs on the processor to be shutdown.
274  */
__cpu_disable(void)275 int __cpu_disable(void)
276 {
277 	unsigned int cpu = smp_processor_id();
278 	int ret;
279 
280 	ret = op_cpu_disable(cpu);
281 	if (ret)
282 		return ret;
283 
284 	/*
285 	 * Take this CPU offline.  Once we clear this, we can't return,
286 	 * and we must not schedule until we're ready to give up the cpu.
287 	 */
288 	set_cpu_online(cpu, false);
289 
290 	/*
291 	 * OK - migrate IRQs away from this CPU
292 	 */
293 	irq_migrate_all_off_this_cpu();
294 
295 	return 0;
296 }
297 
op_cpu_kill(unsigned int cpu)298 static int op_cpu_kill(unsigned int cpu)
299 {
300 	/*
301 	 * If we have no means of synchronising with the dying CPU, then assume
302 	 * that it is really dead. We can only wait for an arbitrary length of
303 	 * time and hope that it's dead, so let's skip the wait and just hope.
304 	 */
305 	if (!cpu_ops[cpu]->cpu_kill)
306 		return 0;
307 
308 	return cpu_ops[cpu]->cpu_kill(cpu);
309 }
310 
311 /*
312  * called on the thread which is asking for a CPU to be shutdown -
313  * waits until shutdown has completed, or it is timed out.
314  */
__cpu_die(unsigned int cpu)315 void __cpu_die(unsigned int cpu)
316 {
317 	int err;
318 
319 	if (!cpu_wait_death(cpu, 5)) {
320 		pr_crit("CPU%u: cpu didn't die\n", cpu);
321 		return;
322 	}
323 	pr_notice("CPU%u: shutdown\n", cpu);
324 
325 	/*
326 	 * Now that the dying CPU is beyond the point of no return w.r.t.
327 	 * in-kernel synchronisation, try to get the firwmare to help us to
328 	 * verify that it has really left the kernel before we consider
329 	 * clobbering anything it might still be using.
330 	 */
331 	err = op_cpu_kill(cpu);
332 	if (err)
333 		pr_warn("CPU%d may not have shut down cleanly: %d\n",
334 			cpu, err);
335 }
336 
337 /*
338  * Called from the idle thread for the CPU which has been shutdown.
339  *
340  * Note that we disable IRQs here, but do not re-enable them
341  * before returning to the caller. This is also the behaviour
342  * of the other hotplug-cpu capable cores, so presumably coming
343  * out of idle fixes this.
344  */
cpu_die(void)345 void cpu_die(void)
346 {
347 	unsigned int cpu = smp_processor_id();
348 
349 	idle_task_exit();
350 
351 	local_irq_disable();
352 
353 	/* Tell __cpu_die() that this CPU is now safe to dispose of */
354 	(void)cpu_report_death();
355 
356 	/*
357 	 * Actually shutdown the CPU. This must never fail. The specific hotplug
358 	 * mechanism must perform all required cache maintenance to ensure that
359 	 * no dirty lines are lost in the process of shutting down the CPU.
360 	 */
361 	cpu_ops[cpu]->cpu_die(cpu);
362 
363 	BUG();
364 }
365 #endif
366 
367 /*
368  * Kill the calling secondary CPU, early in bringup before it is turned
369  * online.
370  */
cpu_die_early(void)371 void cpu_die_early(void)
372 {
373 	int cpu = smp_processor_id();
374 
375 	pr_crit("CPU%d: will not boot\n", cpu);
376 
377 	/* Mark this CPU absent */
378 	set_cpu_present(cpu, 0);
379 
380 #ifdef CONFIG_HOTPLUG_CPU
381 	update_cpu_boot_status(CPU_KILL_ME);
382 	/* Check if we can park ourselves */
383 	if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_die)
384 		cpu_ops[cpu]->cpu_die(cpu);
385 #endif
386 	update_cpu_boot_status(CPU_STUCK_IN_KERNEL);
387 
388 	cpu_park_loop();
389 }
390 
hyp_mode_check(void)391 static void __init hyp_mode_check(void)
392 {
393 	if (is_hyp_mode_available())
394 		pr_info("CPU: All CPU(s) started at EL2\n");
395 	else if (is_hyp_mode_mismatched())
396 		WARN_TAINT(1, TAINT_CPU_OUT_OF_SPEC,
397 			   "CPU: CPUs started in inconsistent modes");
398 	else
399 		pr_info("CPU: All CPU(s) started at EL1\n");
400 }
401 
smp_cpus_done(unsigned int max_cpus)402 void __init smp_cpus_done(unsigned int max_cpus)
403 {
404 	pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
405 	setup_cpu_features();
406 	hyp_mode_check();
407 	apply_alternatives_all();
408 	mark_linear_text_alias_ro();
409 }
410 
smp_prepare_boot_cpu(void)411 void __init smp_prepare_boot_cpu(void)
412 {
413 	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
414 	/*
415 	 * Initialise the static keys early as they may be enabled by the
416 	 * cpufeature code.
417 	 */
418 	jump_label_init();
419 	cpuinfo_store_boot_cpu();
420 }
421 
of_get_cpu_mpidr(struct device_node * dn)422 static u64 __init of_get_cpu_mpidr(struct device_node *dn)
423 {
424 	const __be32 *cell;
425 	u64 hwid;
426 
427 	/*
428 	 * A cpu node with missing "reg" property is
429 	 * considered invalid to build a cpu_logical_map
430 	 * entry.
431 	 */
432 	cell = of_get_property(dn, "reg", NULL);
433 	if (!cell) {
434 		pr_err("%pOF: missing reg property\n", dn);
435 		return INVALID_HWID;
436 	}
437 
438 	hwid = of_read_number(cell, of_n_addr_cells(dn));
439 	/*
440 	 * Non affinity bits must be set to 0 in the DT
441 	 */
442 	if (hwid & ~MPIDR_HWID_BITMASK) {
443 		pr_err("%pOF: invalid reg property\n", dn);
444 		return INVALID_HWID;
445 	}
446 	return hwid;
447 }
448 
449 /*
450  * Duplicate MPIDRs are a recipe for disaster. Scan all initialized
451  * entries and check for duplicates. If any is found just ignore the
452  * cpu. cpu_logical_map was initialized to INVALID_HWID to avoid
453  * matching valid MPIDR values.
454  */
is_mpidr_duplicate(unsigned int cpu,u64 hwid)455 static bool __init is_mpidr_duplicate(unsigned int cpu, u64 hwid)
456 {
457 	unsigned int i;
458 
459 	for (i = 1; (i < cpu) && (i < NR_CPUS); i++)
460 		if (cpu_logical_map(i) == hwid)
461 			return true;
462 	return false;
463 }
464 
465 /*
466  * Initialize cpu operations for a logical cpu and
467  * set it in the possible mask on success
468  */
smp_cpu_setup(int cpu)469 static int __init smp_cpu_setup(int cpu)
470 {
471 	if (cpu_read_ops(cpu))
472 		return -ENODEV;
473 
474 	if (cpu_ops[cpu]->cpu_init(cpu))
475 		return -ENODEV;
476 
477 	set_cpu_possible(cpu, true);
478 
479 	return 0;
480 }
481 
482 static bool bootcpu_valid __initdata;
483 static unsigned int cpu_count = 1;
484 
485 #ifdef CONFIG_ACPI
486 static struct acpi_madt_generic_interrupt cpu_madt_gicc[NR_CPUS];
487 
acpi_cpu_get_madt_gicc(int cpu)488 struct acpi_madt_generic_interrupt *acpi_cpu_get_madt_gicc(int cpu)
489 {
490 	return &cpu_madt_gicc[cpu];
491 }
492 
493 /*
494  * acpi_map_gic_cpu_interface - parse processor MADT entry
495  *
496  * Carry out sanity checks on MADT processor entry and initialize
497  * cpu_logical_map on success
498  */
499 static void __init
acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt * processor)500 acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor)
501 {
502 	u64 hwid = processor->arm_mpidr;
503 
504 	if (!(processor->flags & ACPI_MADT_ENABLED)) {
505 		pr_debug("skipping disabled CPU entry with 0x%llx MPIDR\n", hwid);
506 		return;
507 	}
508 
509 	if (hwid & ~MPIDR_HWID_BITMASK || hwid == INVALID_HWID) {
510 		pr_err("skipping CPU entry with invalid MPIDR 0x%llx\n", hwid);
511 		return;
512 	}
513 
514 	if (is_mpidr_duplicate(cpu_count, hwid)) {
515 		pr_err("duplicate CPU MPIDR 0x%llx in MADT\n", hwid);
516 		return;
517 	}
518 
519 	/* Check if GICC structure of boot CPU is available in the MADT */
520 	if (cpu_logical_map(0) == hwid) {
521 		if (bootcpu_valid) {
522 			pr_err("duplicate boot CPU MPIDR: 0x%llx in MADT\n",
523 			       hwid);
524 			return;
525 		}
526 		bootcpu_valid = true;
527 		cpu_madt_gicc[0] = *processor;
528 		early_map_cpu_to_node(0, acpi_numa_get_nid(0, hwid));
529 		return;
530 	}
531 
532 	if (cpu_count >= NR_CPUS)
533 		return;
534 
535 	/* map the logical cpu id to cpu MPIDR */
536 	cpu_logical_map(cpu_count) = hwid;
537 
538 	cpu_madt_gicc[cpu_count] = *processor;
539 
540 	/*
541 	 * Set-up the ACPI parking protocol cpu entries
542 	 * while initializing the cpu_logical_map to
543 	 * avoid parsing MADT entries multiple times for
544 	 * nothing (ie a valid cpu_logical_map entry should
545 	 * contain a valid parking protocol data set to
546 	 * initialize the cpu if the parking protocol is
547 	 * the only available enable method).
548 	 */
549 	acpi_set_mailbox_entry(cpu_count, processor);
550 
551 	early_map_cpu_to_node(cpu_count, acpi_numa_get_nid(cpu_count, hwid));
552 
553 	cpu_count++;
554 }
555 
556 static int __init
acpi_parse_gic_cpu_interface(struct acpi_subtable_header * header,const unsigned long end)557 acpi_parse_gic_cpu_interface(struct acpi_subtable_header *header,
558 			     const unsigned long end)
559 {
560 	struct acpi_madt_generic_interrupt *processor;
561 
562 	processor = (struct acpi_madt_generic_interrupt *)header;
563 	if (BAD_MADT_GICC_ENTRY(processor, end))
564 		return -EINVAL;
565 
566 	acpi_table_print_madt_entry(header);
567 
568 	acpi_map_gic_cpu_interface(processor);
569 
570 	return 0;
571 }
572 #else
573 #define acpi_table_parse_madt(...)	do { } while (0)
574 #endif
575 
576 /*
577  * Enumerate the possible CPU set from the device tree and build the
578  * cpu logical map array containing MPIDR values related to logical
579  * cpus. Assumes that cpu_logical_map(0) has already been initialized.
580  */
of_parse_and_init_cpus(void)581 static void __init of_parse_and_init_cpus(void)
582 {
583 	struct device_node *dn;
584 
585 	for_each_node_by_type(dn, "cpu") {
586 		u64 hwid = of_get_cpu_mpidr(dn);
587 
588 		if (hwid == INVALID_HWID)
589 			goto next;
590 
591 		if (is_mpidr_duplicate(cpu_count, hwid)) {
592 			pr_err("%pOF: duplicate cpu reg properties in the DT\n",
593 				dn);
594 			goto next;
595 		}
596 
597 		/*
598 		 * The numbering scheme requires that the boot CPU
599 		 * must be assigned logical id 0. Record it so that
600 		 * the logical map built from DT is validated and can
601 		 * be used.
602 		 */
603 		if (hwid == cpu_logical_map(0)) {
604 			if (bootcpu_valid) {
605 				pr_err("%pOF: duplicate boot cpu reg property in DT\n",
606 					dn);
607 				goto next;
608 			}
609 
610 			bootcpu_valid = true;
611 			early_map_cpu_to_node(0, of_node_to_nid(dn));
612 
613 			/*
614 			 * cpu_logical_map has already been
615 			 * initialized and the boot cpu doesn't need
616 			 * the enable-method so continue without
617 			 * incrementing cpu.
618 			 */
619 			continue;
620 		}
621 
622 		if (cpu_count >= NR_CPUS)
623 			goto next;
624 
625 		pr_debug("cpu logical map 0x%llx\n", hwid);
626 		cpu_logical_map(cpu_count) = hwid;
627 
628 		early_map_cpu_to_node(cpu_count, of_node_to_nid(dn));
629 next:
630 		cpu_count++;
631 	}
632 }
633 
634 /*
635  * Enumerate the possible CPU set from the device tree or ACPI and build the
636  * cpu logical map array containing MPIDR values related to logical
637  * cpus. Assumes that cpu_logical_map(0) has already been initialized.
638  */
smp_init_cpus(void)639 void __init smp_init_cpus(void)
640 {
641 	int i;
642 
643 	if (acpi_disabled)
644 		of_parse_and_init_cpus();
645 	else
646 		/*
647 		 * do a walk of MADT to determine how many CPUs
648 		 * we have including disabled CPUs, and get information
649 		 * we need for SMP init
650 		 */
651 		acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
652 				      acpi_parse_gic_cpu_interface, 0);
653 
654 	if (cpu_count > nr_cpu_ids)
655 		pr_warn("Number of cores (%d) exceeds configured maximum of %u - clipping\n",
656 			cpu_count, nr_cpu_ids);
657 
658 	if (!bootcpu_valid) {
659 		pr_err("missing boot CPU MPIDR, not enabling secondaries\n");
660 		return;
661 	}
662 
663 	/*
664 	 * We need to set the cpu_logical_map entries before enabling
665 	 * the cpus so that cpu processor description entries (DT cpu nodes
666 	 * and ACPI MADT entries) can be retrieved by matching the cpu hwid
667 	 * with entries in cpu_logical_map while initializing the cpus.
668 	 * If the cpu set-up fails, invalidate the cpu_logical_map entry.
669 	 */
670 	for (i = 1; i < nr_cpu_ids; i++) {
671 		if (cpu_logical_map(i) != INVALID_HWID) {
672 			if (smp_cpu_setup(i))
673 				cpu_logical_map(i) = INVALID_HWID;
674 		}
675 	}
676 }
677 
smp_prepare_cpus(unsigned int max_cpus)678 void __init smp_prepare_cpus(unsigned int max_cpus)
679 {
680 	int err;
681 	unsigned int cpu;
682 	unsigned int this_cpu;
683 
684 	init_cpu_topology();
685 
686 	this_cpu = smp_processor_id();
687 	store_cpu_topology(this_cpu);
688 	numa_store_cpu_info(this_cpu);
689 
690 	/*
691 	 * If UP is mandated by "nosmp" (which implies "maxcpus=0"), don't set
692 	 * secondary CPUs present.
693 	 */
694 	if (max_cpus == 0)
695 		return;
696 
697 	/*
698 	 * Initialise the present map (which describes the set of CPUs
699 	 * actually populated at the present time) and release the
700 	 * secondaries from the bootloader.
701 	 */
702 	for_each_possible_cpu(cpu) {
703 
704 		per_cpu(cpu_number, cpu) = cpu;
705 
706 		if (cpu == smp_processor_id())
707 			continue;
708 
709 		if (!cpu_ops[cpu])
710 			continue;
711 
712 		err = cpu_ops[cpu]->cpu_prepare(cpu);
713 		if (err)
714 			continue;
715 
716 		set_cpu_present(cpu, true);
717 		numa_store_cpu_info(cpu);
718 	}
719 }
720 
721 void (*__smp_cross_call)(const struct cpumask *, unsigned int);
722 
set_smp_cross_call(void (* fn)(const struct cpumask *,unsigned int))723 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
724 {
725 	__smp_cross_call = fn;
726 }
727 
728 static const char *ipi_types[NR_IPI] __tracepoint_string = {
729 #define S(x,s)	[x] = s
730 	S(IPI_RESCHEDULE, "Rescheduling interrupts"),
731 	S(IPI_CALL_FUNC, "Function call interrupts"),
732 	S(IPI_CPU_STOP, "CPU stop interrupts"),
733 	S(IPI_CPU_CRASH_STOP, "CPU stop (for crash dump) interrupts"),
734 	S(IPI_TIMER, "Timer broadcast interrupts"),
735 	S(IPI_IRQ_WORK, "IRQ work interrupts"),
736 	S(IPI_WAKEUP, "CPU wake-up interrupts"),
737 };
738 
smp_cross_call(const struct cpumask * target,unsigned int ipinr)739 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
740 {
741 	trace_ipi_raise(target, ipi_types[ipinr]);
742 	__smp_cross_call(target, ipinr);
743 }
744 
show_ipi_list(struct seq_file * p,int prec)745 void show_ipi_list(struct seq_file *p, int prec)
746 {
747 	unsigned int cpu, i;
748 
749 	for (i = 0; i < NR_IPI; i++) {
750 		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
751 			   prec >= 4 ? " " : "");
752 		for_each_online_cpu(cpu)
753 			seq_printf(p, "%10u ",
754 				   __get_irq_stat(cpu, ipi_irqs[i]));
755 		seq_printf(p, "      %s\n", ipi_types[i]);
756 	}
757 }
758 
smp_irq_stat_cpu(unsigned int cpu)759 u64 smp_irq_stat_cpu(unsigned int cpu)
760 {
761 	u64 sum = 0;
762 	int i;
763 
764 	for (i = 0; i < NR_IPI; i++)
765 		sum += __get_irq_stat(cpu, ipi_irqs[i]);
766 
767 	return sum;
768 }
769 
arch_send_call_function_ipi_mask(const struct cpumask * mask)770 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
771 {
772 	smp_cross_call(mask, IPI_CALL_FUNC);
773 }
774 
arch_send_call_function_single_ipi(int cpu)775 void arch_send_call_function_single_ipi(int cpu)
776 {
777 	smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
778 }
779 
780 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
arch_send_wakeup_ipi_mask(const struct cpumask * mask)781 void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
782 {
783 	smp_cross_call(mask, IPI_WAKEUP);
784 }
785 #endif
786 
787 #ifdef CONFIG_IRQ_WORK
arch_irq_work_raise(void)788 void arch_irq_work_raise(void)
789 {
790 	if (__smp_cross_call)
791 		smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
792 }
793 #endif
794 
795 /*
796  * ipi_cpu_stop - handle IPI from smp_send_stop()
797  */
ipi_cpu_stop(unsigned int cpu)798 static void ipi_cpu_stop(unsigned int cpu)
799 {
800 	set_cpu_online(cpu, false);
801 
802 	local_irq_disable();
803 
804 	while (1)
805 		cpu_relax();
806 }
807 
808 #ifdef CONFIG_KEXEC_CORE
809 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
810 #endif
811 
ipi_cpu_crash_stop(unsigned int cpu,struct pt_regs * regs)812 static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
813 {
814 #ifdef CONFIG_KEXEC_CORE
815 	crash_save_cpu(regs, cpu);
816 
817 	atomic_dec(&waiting_for_crash_ipi);
818 
819 	local_irq_disable();
820 
821 #ifdef CONFIG_HOTPLUG_CPU
822 	if (cpu_ops[cpu]->cpu_die)
823 		cpu_ops[cpu]->cpu_die(cpu);
824 #endif
825 
826 	/* just in case */
827 	cpu_park_loop();
828 #endif
829 }
830 
831 /*
832  * Main handler for inter-processor interrupts
833  */
handle_IPI(int ipinr,struct pt_regs * regs)834 void handle_IPI(int ipinr, struct pt_regs *regs)
835 {
836 	unsigned int cpu = smp_processor_id();
837 	struct pt_regs *old_regs = set_irq_regs(regs);
838 
839 	if ((unsigned)ipinr < NR_IPI) {
840 		trace_ipi_entry_rcuidle(ipi_types[ipinr]);
841 		__inc_irq_stat(cpu, ipi_irqs[ipinr]);
842 	}
843 
844 	switch (ipinr) {
845 	case IPI_RESCHEDULE:
846 		scheduler_ipi();
847 		break;
848 
849 	case IPI_CALL_FUNC:
850 		irq_enter();
851 		generic_smp_call_function_interrupt();
852 		irq_exit();
853 		break;
854 
855 	case IPI_CPU_STOP:
856 		irq_enter();
857 		ipi_cpu_stop(cpu);
858 		irq_exit();
859 		break;
860 
861 	case IPI_CPU_CRASH_STOP:
862 		if (IS_ENABLED(CONFIG_KEXEC_CORE)) {
863 			irq_enter();
864 			ipi_cpu_crash_stop(cpu, regs);
865 
866 			unreachable();
867 		}
868 		break;
869 
870 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
871 	case IPI_TIMER:
872 		irq_enter();
873 		tick_receive_broadcast();
874 		irq_exit();
875 		break;
876 #endif
877 
878 #ifdef CONFIG_IRQ_WORK
879 	case IPI_IRQ_WORK:
880 		irq_enter();
881 		irq_work_run();
882 		irq_exit();
883 		break;
884 #endif
885 
886 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
887 	case IPI_WAKEUP:
888 		WARN_ONCE(!acpi_parking_protocol_valid(cpu),
889 			  "CPU%u: Wake-up IPI outside the ACPI parking protocol\n",
890 			  cpu);
891 		break;
892 #endif
893 
894 	default:
895 		pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
896 		break;
897 	}
898 
899 	if ((unsigned)ipinr < NR_IPI)
900 		trace_ipi_exit_rcuidle(ipi_types[ipinr]);
901 	set_irq_regs(old_regs);
902 }
903 
smp_send_reschedule(int cpu)904 void smp_send_reschedule(int cpu)
905 {
906 	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
907 }
908 
909 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
tick_broadcast(const struct cpumask * mask)910 void tick_broadcast(const struct cpumask *mask)
911 {
912 	smp_cross_call(mask, IPI_TIMER);
913 }
914 #endif
915 
916 /*
917  * The number of CPUs online, not counting this CPU (which may not be
918  * fully online and so not counted in num_online_cpus()).
919  */
num_other_online_cpus(void)920 static inline unsigned int num_other_online_cpus(void)
921 {
922 	unsigned int this_cpu_online = cpu_online(smp_processor_id());
923 
924 	return num_online_cpus() - this_cpu_online;
925 }
926 
smp_send_stop(void)927 void smp_send_stop(void)
928 {
929 	unsigned long timeout;
930 
931 	if (num_other_online_cpus()) {
932 		cpumask_t mask;
933 
934 		cpumask_copy(&mask, cpu_online_mask);
935 		cpumask_clear_cpu(smp_processor_id(), &mask);
936 
937 		if (system_state <= SYSTEM_RUNNING)
938 			pr_crit("SMP: stopping secondary CPUs\n");
939 		smp_cross_call(&mask, IPI_CPU_STOP);
940 	}
941 
942 	/* Wait up to one second for other CPUs to stop */
943 	timeout = USEC_PER_SEC;
944 	while (num_other_online_cpus() && timeout--)
945 		udelay(1);
946 
947 	if (num_other_online_cpus())
948 		pr_warning("SMP: failed to stop secondary CPUs %*pbl\n",
949 			   cpumask_pr_args(cpu_online_mask));
950 }
951 
952 #ifdef CONFIG_KEXEC_CORE
crash_smp_send_stop(void)953 void crash_smp_send_stop(void)
954 {
955 	static int cpus_stopped;
956 	cpumask_t mask;
957 	unsigned long timeout;
958 
959 	/*
960 	 * This function can be called twice in panic path, but obviously
961 	 * we execute this only once.
962 	 */
963 	if (cpus_stopped)
964 		return;
965 
966 	cpus_stopped = 1;
967 
968 	/*
969 	 * If this cpu is the only one alive at this point in time, online or
970 	 * not, there are no stop messages to be sent around, so just back out.
971 	 */
972 	if (num_other_online_cpus() == 0)
973 		return;
974 
975 	cpumask_copy(&mask, cpu_online_mask);
976 	cpumask_clear_cpu(smp_processor_id(), &mask);
977 
978 	atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
979 
980 	pr_crit("SMP: stopping secondary CPUs\n");
981 	smp_cross_call(&mask, IPI_CPU_CRASH_STOP);
982 
983 	/* Wait up to one second for other CPUs to stop */
984 	timeout = USEC_PER_SEC;
985 	while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
986 		udelay(1);
987 
988 	if (atomic_read(&waiting_for_crash_ipi) > 0)
989 		pr_warning("SMP: failed to stop secondary CPUs %*pbl\n",
990 			   cpumask_pr_args(&mask));
991 }
992 
smp_crash_stop_failed(void)993 bool smp_crash_stop_failed(void)
994 {
995 	return (atomic_read(&waiting_for_crash_ipi) > 0);
996 }
997 #endif
998 
999 /*
1000  * not supported here
1001  */
setup_profiling_timer(unsigned int multiplier)1002 int setup_profiling_timer(unsigned int multiplier)
1003 {
1004 	return -EINVAL;
1005 }
1006 
have_cpu_die(void)1007 static bool have_cpu_die(void)
1008 {
1009 #ifdef CONFIG_HOTPLUG_CPU
1010 	int any_cpu = raw_smp_processor_id();
1011 
1012 	if (cpu_ops[any_cpu] && cpu_ops[any_cpu]->cpu_die)
1013 		return true;
1014 #endif
1015 	return false;
1016 }
1017 
cpus_are_stuck_in_kernel(void)1018 bool cpus_are_stuck_in_kernel(void)
1019 {
1020 	bool smp_spin_tables = (num_possible_cpus() > 1 && !have_cpu_die());
1021 
1022 	return !!cpus_stuck_in_kernel || smp_spin_tables;
1023 }
1024