aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm/kernel/smp.c
blob: a07d202143c33b958100346335d83cbf650aec96 (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
/*
 *  linux/arch/arm/kernel/smp.c
 *
 *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/seq_file.h>
#include <linux/irq.h>

#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>

/*
 * bitmask of present and online CPUs.
 * The present bitmask indicates that the CPU is physically present.
 * The online bitmask indicates that the CPU is up and running.
 */
cpumask_t cpu_possible_map;
EXPORT_SYMBOL(cpu_possible_map);
cpumask_t cpu_online_map;
EXPORT_SYMBOL(cpu_online_map);

/*
 * 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;

/*
 * structures for inter-processor calls
 * - A collection of single bit ipi messages.
 */
struct ipi_data {
	spinlock_t lock;
	unsigned long ipi_count;
	unsigned long bits;
};

static DEFINE_PER_CPU(struct ipi_data, ipi_data) = {
	.lock	= SPIN_LOCK_UNLOCKED,
};

enum ipi_msg_type {
	IPI_TIMER,
	IPI_RESCHEDULE,
	IPI_CALL_FUNC,
	IPI_CPU_STOP,
};

struct smp_call_struct {
	void (*func)(void *info);
	void *info;
	int wait;
	cpumask_t pending;
	cpumask_t unfinished;
};

static struct smp_call_struct * volatile smp_call_function_data;
static DEFINE_SPINLOCK(smp_call_function_lock);

int __cpuinit __cpu_up(unsigned int cpu)
{
	struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
	struct task_struct *idle = ci->idle;
	pgd_t *pgd;
	pmd_t *pmd;
	int ret;

	/*
	 * Spawn a new process manually, if not already done.
	 * Grab a pointer to its task struct so we can mess with it
	 */
	if (!idle) {
		idle = fork_idle(cpu);
		if (IS_ERR(idle)) {
			printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
			return PTR_ERR(idle);
		}
		ci->idle = idle;
	}

	/*
	 * Allocate initial page tables to allow the new CPU to
	 * enable the MMU safely.  This essentially means a set
	 * of our "standard" page tables, with the addition of
	 * a 1:1 mapping for the physical address of the kernel.
	 */
	pgd = pgd_alloc(&init_mm);
	pmd = pmd_offset(pgd, PHYS_OFFSET);
	*pmd = __pmd((PHYS_OFFSET & PGDIR_MASK) |
		     PMD_TYPE_SECT | PMD_SECT_AP_WRITE);

	/*
	 * We need to tell the secondary core where to find
	 * its stack and the page tables.
	 */
	secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
	secondary_data.pgdir = virt_to_phys(pgd);
	wmb();

	/*
	 * Now bring the CPU into our world.
	 */
	ret = boot_secondary(cpu, idle);
	if (ret == 0) {
		unsigned long timeout;

		/*
		 * CPU was successfully started, wait for it
		 * to come online or time out.
		 */
		timeout = jiffies + HZ;
		while (time_before(jiffies, timeout)) {
			if (cpu_online(cpu))
				break;

			udelay(10);
			barrier();
		}

		if (!cpu_online(cpu))
			ret = -EIO;
	}

	secondary_data.stack = NULL;
	secondary_data.pgdir = 0;

	*pmd_offset(pgd, PHYS_OFFSET) = __pmd(0);
	pgd_free(pgd);

	if (ret) {
		printk(KERN_CRIT "CPU%u: processor failed to boot\n", cpu);

		/*
		 * FIXME: We need to clean up the new idle thread. --rmk
		 */
	}

	return ret;
}

#ifdef CONFIG_HOTPLUG_CPU
/*
 * __cpu_disable runs on the processor to be shutdown.
 */
int __cpuexit __cpu_disable(void)
{
	unsigned int cpu = smp_processor_id();
	struct task_struct *p;
	int ret;

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

	/*
	 * 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.
	 */
	cpu_clear(cpu, cpu_online_map);

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

	/*
	 * Stop the local timer for this CPU.
	 */
	local_timer_stop(cpu);

	/*
	 * Flush user cache and TLB mappings, and then remove this CPU
	 * from the vm mask set of all processes.
	 */
	flush_cache_all();
	local_flush_tlb_all();

	read_lock(&tasklist_lock);
	for_each_process(p) {
		if (p->mm)
			cpu_clear(cpu, p->mm->cpu_vm_mask);
	}
	read_unlock(&tasklist_lock);

	return 0;
}

/*
 * called on the thread which is asking for a CPU to be shutdown -
 * waits until shutdown has completed, or it is timed out.
 */
void __cpuexit __cpu_die(unsigned int cpu)
{
	if (!platform_cpu_kill(cpu))
		printk("CPU%u: unable to kill\n", cpu);
}

/*
 * Called from the idle thread for the CPU which has been shutdown.
 *
 * Note that we disable IRQs here, but do not re-enable them
 * before returning to the caller. This is also the behaviour
 * of the other hotplug-cpu capable cores, so presumably coming
 * out of idle fixes this.
 */
void __cpuexit cpu_die(void)
{
	unsigned int cpu = smp_processor_id();

	local_irq_disable();
	idle_task_exit();

	/*
	 * actual CPU shutdown procedure is at least platform (if not
	 * CPU) specific
	 */
	platform_cpu_die(cpu);

	/*
	 * Do not return to the idle loop - jump back to the secondary
	 * cpu initialisation.  There's some initialisation which needs
	 * to be repeated to undo the effects of taking the CPU offline.
	 */
	__asm__("mov	sp, %0\n"
	"	b	secondary_start_kernel"
		:
		: "r" (task_stack_page(current) + THREAD_SIZE - 8));
}
#endif /* CONFIG_HOTPLUG_CPU */

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

	printk("CPU%u: Booted secondary processor\n", cpu);

	/*
	 * All kernel threads share the same mm context; grab a
	 * reference and switch to it.
	 */
	atomic_inc(&mm->mm_users);
	atomic_inc(&mm->mm_count);
	current->active_mm = mm;
	cpu_set(cpu, mm->cpu_vm_mask);
	cpu_switch_mm(mm->pgd, mm);
	enter_lazy_tlb(mm, current);
	local_flush_tlb_all();

	cpu_init();
	preempt_disable();

	/*
	 * Give the platform a chance to do its own initialisation.
	 */
	platform_secondary_init(cpu);

	/*
	 * Enable local interrupts.
	 */
	local_irq_enable();
	local_fiq_enable();

	calibrate_delay();

	smp_store_cpu_info(cpu);

	/*
	 * OK, now it's safe to let the boot CPU continue
	 */
	cpu_set(cpu, cpu_online_map);

	/*
	 * Setup local timer for this CPU.
	 */
	local_timer_setup(cpu);

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

/*
 * Called by both boot and secondaries to move global data into
 * per-processor storage.
 */
void __cpuinit smp_store_cpu_info(unsigned int cpuid)
{
	struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);

	cpu_info->loops_per_jiffy = loops_per_jiffy;
}

void __init smp_cpus_done(unsigned int max_cpus)
{
	int cpu;
	unsigned long bogosum = 0;

	for_each_online_cpu(cpu)
		bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;

	printk(KERN_INFO "SMP: Total of %d processors activated "
	       "(%lu.%02lu BogoMIPS).\n",
	       num_online_cpus(),
	       bogosum / (500000/HZ),
	       (bogosum / (5000/HZ)) % 100);
}

void __init smp_prepare_boot_cpu(void)
{
	unsigned int cpu = smp_processor_id();

	per_cpu(cpu_data, cpu).idle = current;
}

static void send_ipi_message(cpumask_t callmap, enum ipi_msg_type msg)
{
	unsigned long flags;
	unsigned int cpu;

	local_irq_save(flags);

	for_each_cpu_mask(cpu, callmap) {
		struct ipi_data *ipi = &per_cpu(ipi_data, cpu);

		spin_lock(&ipi->lock);
		ipi->bits |= 1 << msg;
		spin_unlock(&ipi->lock);
	}

	/*
	 * Call the platform specific cross-CPU call function.
	 */
	smp_cross_call(callmap);

	local_irq_restore(flags);
}

/*
 * You must not call this function with disabled interrupts, from a
 * hardware interrupt handler, nor from a bottom half handler.
 */
static int smp_call_function_on_cpu(void (*func)(void *info), void *info,
				    int retry, int wait, cpumask_t callmap)
{
	struct smp_call_struct data;
	unsigned long timeout;
	int ret = 0;

	data.func = func;
	data.info = info;
	data.wait = wait;

	cpu_clear(smp_processor_id(), callmap);
	if (cpus_empty(callmap))
		goto out;

	data.pending = callmap;
	if (wait)
		data.unfinished = callmap;

	/*
	 * try to get the mutex on smp_call_function_data
	 */
	spin_lock(&smp_call_function_lock);
	smp_call_function_data = &data;

	send_ipi_message(callmap, IPI_CALL_FUNC);

	timeout = jiffies + HZ;
	while (!cpus_empty(data.pending) && time_before(jiffies, timeout))
		barrier();

	/*
	 * did we time out?
	 */
	if (!cpus_empty(data.pending)) {
		/*
		 * this may be causing our panic - report it
		 */
		printk(KERN_CRIT
		       "CPU%u: smp_call_function timeout for %p(%p)\n"
		       "      callmap %lx pending %lx, %swait\n",
		       smp_processor_id(), func, info, *cpus_addr(callmap),
		       *cpus_addr(data.pending), wait ? "" : "no ");

		/*
		 * TRACE
		 */
		timeout = jiffies + (5 * HZ);
		while (!cpus_empty(data.pending) && time_before(jiffies, timeout))
			barrier();

		if (cpus_empty(data.pending))
			printk(KERN_CRIT "     RESOLVED\n");
		else
			printk(KERN_CRIT "     STILL STUCK\n");
	}

	/*
	 * whatever happened, we're done with the data, so release it
	 */
	smp_call_function_data = NULL;
	spin_unlock(&smp_call_function_lock);

	if (!cpus_empty(data.pending)) {
		ret = -ETIMEDOUT;
		goto out;
	}

	if (wait)
		while (!cpus_empty(data.unfinished))
			barrier();
 out:

	return 0;
}

int smp_call_function(void (*func)(void *info), void *info, int retry,
                      int wait)
{
	return smp_call_function_on_cpu(func, info, retry, wait,
					cpu_online_map);
}

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

	seq_puts(p, "IPI:");

	for_each_present_cpu(cpu)
		seq_printf(p, " %10lu", per_cpu(ipi_data, cpu).ipi_count);

	seq_putc(p, '\n');
}

void show_local_irqs(struct seq_file *p)
{
	unsigned int cpu;

	seq_printf(p, "LOC: ");

	for_each_present_cpu(cpu)
		seq_printf(p, "%10u ", irq_stat[cpu].local_timer_irqs);

	seq_putc(p, '\n');
}

static void ipi_timer(void)
{
	irq_enter();
	profile_tick(CPU_PROFILING);
	update_process_times(user_mode(get_irq_regs()));
	irq_exit();
}

#ifdef CONFIG_LOCAL_TIMERS
asmlinkage void do_local_timer(struct pt_regs *regs)
{
	struct pt_regs *old_regs = set_irq_regs(regs);
	int cpu = smp_processor_id();

	if (local_timer_ack()) {
		irq_stat[cpu].local_timer_irqs++;
		ipi_timer();
	}

	set_irq_regs(old_regs);
}
#endif

/*
 * ipi_call_function - handle IPI from smp_call_function()
 *
 * Note that we copy data out of the cross-call structure and then
 * let the caller know that we're here and have done with their data
 */
static void ipi_call_function(unsigned int cpu)
{
	struct smp_call_struct *data = smp_call_function_data;
	void (*func)(void *info) = data->func;
	void *info = data->info;
	int wait = data->wait;

	cpu_clear(cpu, data->pending);

	func(info);

	if (wait)
		cpu_clear(cpu, data->unfinished);
}

static DEFINE_SPINLOCK(stop_lock);

/*
 * ipi_cpu_stop - handle IPI from smp_send_stop()
 */
static void ipi_cpu_stop(unsigned int cpu)
{
	spin_lock(&stop_lock);
	printk(KERN_CRIT "CPU%u: stopping\n", cpu);
	dump_stack();
	spin_unlock(&stop_lock);

	cpu_clear(cpu, cpu_online_map);

	local_fiq_disable();
	local_irq_disable();

	while (1)
		cpu_relax();
}

/*
 * Main handler for inter-processor interrupts
 *
 * For ARM, the ipimask now only identifies a single
 * category of IPI (Bit 1 IPIs have been replaced by a
 * different mechanism):
 *
 *  Bit 0 - Inter-processor function call
 */
asmlinkage void do_IPI(struct pt_regs *regs)
{
	unsigned int cpu = smp_processor_id();
	struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
	struct pt_regs *old_regs = set_irq_regs(regs);

	ipi->ipi_count++;

	for (;;) {
		unsigned long msgs;

		spin_lock(&ipi->lock);
		msgs = ipi->bits;
		ipi->bits = 0;
		spin_unlock(&ipi->lock);

		if (!msgs)
			break;

		do {
			unsigned nextmsg;

			nextmsg = msgs & -msgs;
			msgs &= ~nextmsg;
			nextmsg = ffz(~nextmsg);

			switch (nextmsg) {
			case IPI_TIMER:
				ipi_timer();
				break;

			case IPI_RESCHEDULE:
				/*
				 * nothing more to do - eveything is
				 * done on the interrupt return path
				 */
				break;

			case IPI_CALL_FUNC:
				ipi_call_function(cpu);
				break;

			case IPI_CPU_STOP:
				ipi_cpu_stop(cpu);
				break;

			default:
				printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
				       cpu, nextmsg);
				break;
			}
		} while (msgs);
	}

	set_irq_regs(old_regs);
}

void smp_send_reschedule(int cpu)
{
	send_ipi_message(cpumask_of_cpu(cpu), IPI_RESCHEDULE);
}

void smp_send_timer(void)
{
	cpumask_t mask = cpu_online_map;
	cpu_clear(smp_processor_id(), mask);
	send_ipi_message(mask, IPI_TIMER);
}

void smp_send_stop(void)
{
	cpumask_t mask = cpu_online_map;
	cpu_clear(smp_processor_id(), mask);
	send_ipi_message(mask, IPI_CPU_STOP);
}

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

static int
on_each_cpu_mask(void (*func)(void *), void *info, int retry, int wait,
		 cpumask_t mask)
{
	int ret = 0;

	preempt_disable();

	ret = smp_call_function_on_cpu(func, info, retry, wait, mask);
	if (cpu_isset(smp_processor_id(), mask))
		func(info);

	preempt_enable();

	return ret;
}

/**********************************************************************/

/*
 * TLB operations
 */
struct tlb_args {
	struct vm_area_struct *ta_vma;
	unsigned long ta_start;
	unsigned long ta_end;
};

static inline void ipi_flush_tlb_all(void *ignored)
{
	local_flush_tlb_all();
}

static inline void ipi_flush_tlb_mm(void *arg)
{
	struct mm_struct *mm = (struct mm_struct *)arg;

	local_flush_tlb_mm(mm);
}

static inline void ipi_flush_tlb_page(void *arg)
{
	struct tlb_args *ta = (struct tlb_args *)arg;

	local_flush_tlb_page(ta->ta_vma, ta->ta_start);
}

static inline void ipi_flush_tlb_kernel_page(void *arg)
{
	struct tlb_args *ta = (struct tlb_args *)arg;

	local_flush_tlb_kernel_page(ta->ta_start);
}

static inline void ipi_flush_tlb_range(void *arg)
{
	struct tlb_args *ta = (struct tlb_args *)arg;

	local_flush_tlb_range(ta->ta_vma, ta->ta_start, ta->ta_end);
}

static inline void ipi_flush_tlb_kernel_range(void *arg)
{
	struct tlb_args *ta = (struct tlb_args *)arg;

	local_flush_tlb_kernel_range(ta->ta_start, ta->ta_end);
}

void flush_tlb_all(void)
{
	on_each_cpu(ipi_flush_tlb_all, NULL, 1, 1);
}

void flush_tlb_mm(struct mm_struct *mm)
{
	cpumask_t mask = mm->cpu_vm_mask;

	on_each_cpu_mask(ipi_flush_tlb_mm, mm, 1, 1, mask);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
	cpumask_t mask = vma->vm_mm->cpu_vm_mask;
	struct tlb_args ta;

	ta.ta_vma = vma;
	ta.ta_start = uaddr;

	on_each_cpu_mask(ipi_flush_tlb_page, &ta, 1, 1, mask);
}

void flush_tlb_kernel_page(unsigned long kaddr)
{
	struct tlb_args ta;

	ta.ta_start = kaddr;

	on_each_cpu(ipi_flush_tlb_kernel_page, &ta, 1, 1);
}

void flush_tlb_range(struct vm_area_struct *vma,
                     unsigned long start, unsigned long end)
{
	cpumask_t mask = vma->vm_mm->cpu_vm_mask;
	struct tlb_args ta;

	ta.ta_vma = vma;
	ta.ta_start = start;
	ta.ta_end = end;

	on_each_cpu_mask(ipi_flush_tlb_range, &ta, 1, 1, mask);
}

void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
	struct tlb_args ta;

	ta.ta_start = start;
	ta.ta_end = end;

	on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1, 1);
}