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Linux/arch/arm/kernel/smp.c

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  1 /*
  2  *  linux/arch/arm/kernel/smp.c
  3  *
  4  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
  5  *
  6  * This program is free software; you can redistribute it and/or modify
  7  * it under the terms of the GNU General Public License version 2 as
  8  * published by the Free Software Foundation.
  9  */
 10 #include <linux/module.h>
 11 #include <linux/delay.h>
 12 #include <linux/init.h>
 13 #include <linux/spinlock.h>
 14 #include <linux/sched.h>
 15 #include <linux/interrupt.h>
 16 #include <linux/cache.h>
 17 #include <linux/profile.h>
 18 #include <linux/errno.h>
 19 #include <linux/mm.h>
 20 #include <linux/err.h>
 21 #include <linux/cpu.h>
 22 #include <linux/smp.h>
 23 #include <linux/seq_file.h>
 24 #include <linux/irq.h>
 25 #include <linux/percpu.h>
 26 #include <linux/clockchips.h>
 27 #include <linux/completion.h>
 28 
 29 #include <linux/atomic.h>
 30 #include <asm/cacheflush.h>
 31 #include <asm/cpu.h>
 32 #include <asm/cputype.h>
 33 #include <asm/exception.h>
 34 #include <asm/topology.h>
 35 #include <asm/mmu_context.h>
 36 #include <asm/pgtable.h>
 37 #include <asm/pgalloc.h>
 38 #include <asm/processor.h>
 39 #include <asm/sections.h>
 40 #include <asm/tlbflush.h>
 41 #include <asm/ptrace.h>
 42 #include <asm/localtimer.h>
 43 #include <asm/smp_plat.h>
 44 
 45 /*
 46  * as from 2.5, kernels no longer have an init_tasks structure
 47  * so we need some other way of telling a new secondary core
 48  * where to place its SVC stack
 49  */
 50 struct secondary_data secondary_data;
 51 
 52 enum ipi_msg_type {
 53         IPI_TIMER = 2,
 54         IPI_RESCHEDULE,
 55         IPI_CALL_FUNC,
 56         IPI_CALL_FUNC_SINGLE,
 57         IPI_CPU_STOP,
 58 };
 59 
 60 int __cpuinit __cpu_up(unsigned int cpu)
 61 {
 62         struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
 63         struct task_struct *idle = ci->idle;
 64         pgd_t *pgd;
 65         int ret;
 66 
 67         /*
 68          * Spawn a new process manually, if not already done.
 69          * Grab a pointer to its task struct so we can mess with it
 70          */
 71         if (!idle) {
 72                 idle = fork_idle(cpu);
 73                 if (IS_ERR(idle)) {
 74                         printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
 75                         return PTR_ERR(idle);
 76                 }
 77                 ci->idle = idle;
 78         } else {
 79                 /*
 80                  * Since this idle thread is being re-used, call
 81                  * init_idle() to reinitialize the thread structure.
 82                  */
 83                 init_idle(idle, cpu);
 84         }
 85 
 86         /*
 87          * Allocate initial page tables to allow the new CPU to
 88          * enable the MMU safely.  This essentially means a set
 89          * of our "standard" page tables, with the addition of
 90          * a 1:1 mapping for the physical address of the kernel.
 91          */
 92         pgd = pgd_alloc(&init_mm);
 93         if (!pgd)
 94                 return -ENOMEM;
 95 
 96         if (PHYS_OFFSET != PAGE_OFFSET) {
 97 #ifndef CONFIG_HOTPLUG_CPU
 98                 identity_mapping_add(pgd, __pa(__init_begin), __pa(__init_end));
 99 #endif
100                 identity_mapping_add(pgd, __pa(_stext), __pa(_etext));
101                 identity_mapping_add(pgd, __pa(_sdata), __pa(_edata));
102         }
103 
104         /*
105          * We need to tell the secondary core where to find
106          * its stack and the page tables.
107          */
108         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
109         secondary_data.pgdir = virt_to_phys(pgd);
110         secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
111         __cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
112         outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));
113 
114         /*
115          * Now bring the CPU into our world.
116          */
117         ret = boot_secondary(cpu, idle);
118         if (ret == 0) {
119                 unsigned long timeout;
120 
121                 /*
122                  * CPU was successfully started, wait for it
123                  * to come online or time out.
124                  */
125                 timeout = jiffies + HZ;
126                 while (time_before(jiffies, timeout)) {
127                         if (cpu_online(cpu))
128                                 break;
129 
130                         udelay(10);
131                         barrier();
132                 }
133 
134                 if (!cpu_online(cpu)) {
135                         pr_crit("CPU%u: failed to come online\n", cpu);
136                         ret = -EIO;
137                 }
138         } else {
139                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
140         }
141 
142         secondary_data.stack = NULL;
143         secondary_data.pgdir = 0;
144 
145         if (PHYS_OFFSET != PAGE_OFFSET) {
146 #ifndef CONFIG_HOTPLUG_CPU
147                 identity_mapping_del(pgd, __pa(__init_begin), __pa(__init_end));
148 #endif
149                 identity_mapping_del(pgd, __pa(_stext), __pa(_etext));
150                 identity_mapping_del(pgd, __pa(_sdata), __pa(_edata));
151         }
152 
153         pgd_free(&init_mm, pgd);
154 
155         return ret;
156 }
157 
158 #ifdef CONFIG_HOTPLUG_CPU
159 static void percpu_timer_stop(void);
160 
161 /*
162  * __cpu_disable runs on the processor to be shutdown.
163  */
164 int __cpu_disable(void)
165 {
166         unsigned int cpu = smp_processor_id();
167         struct task_struct *p;
168         int ret;
169 
170         ret = platform_cpu_disable(cpu);
171         if (ret)
172                 return ret;
173 
174         /*
175          * Take this CPU offline.  Once we clear this, we can't return,
176          * and we must not schedule until we're ready to give up the cpu.
177          */
178         set_cpu_online(cpu, false);
179 
180         /*
181          * OK - migrate IRQs away from this CPU
182          */
183         migrate_irqs();
184 
185         /*
186          * Stop the local timer for this CPU.
187          */
188         percpu_timer_stop();
189 
190         /*
191          * Flush user cache and TLB mappings, and then remove this CPU
192          * from the vm mask set of all processes.
193          */
194         flush_cache_all();
195         local_flush_tlb_all();
196 
197         read_lock(&tasklist_lock);
198         for_each_process(p) {
199                 if (p->mm)
200                         cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
201         }
202         read_unlock(&tasklist_lock);
203 
204         return 0;
205 }
206 
207 static DECLARE_COMPLETION(cpu_died);
208 
209 /*
210  * called on the thread which is asking for a CPU to be shutdown -
211  * waits until shutdown has completed, or it is timed out.
212  */
213 void __cpu_die(unsigned int cpu)
214 {
215         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
216                 pr_err("CPU%u: cpu didn't die\n", cpu);
217                 return;
218         }
219         printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
220 
221         if (!platform_cpu_kill(cpu))
222                 printk("CPU%u: unable to kill\n", cpu);
223 }
224 
225 /*
226  * Called from the idle thread for the CPU which has been shutdown.
227  *
228  * Note that we disable IRQs here, but do not re-enable them
229  * before returning to the caller. This is also the behaviour
230  * of the other hotplug-cpu capable cores, so presumably coming
231  * out of idle fixes this.
232  */
233 void __ref cpu_die(void)
234 {
235         unsigned int cpu = smp_processor_id();
236 
237         idle_task_exit();
238 
239         local_irq_disable();
240         mb();
241 
242         /* Tell __cpu_die() that this CPU is now safe to dispose of */
243         complete(&cpu_died);
244 
245         /*
246          * actual CPU shutdown procedure is at least platform (if not
247          * CPU) specific.
248          */
249         platform_cpu_die(cpu);
250 
251         /*
252          * Do not return to the idle loop - jump back to the secondary
253          * cpu initialisation.  There's some initialisation which needs
254          * to be repeated to undo the effects of taking the CPU offline.
255          */
256         __asm__("mov    sp, %0\n"
257         "       mov     fp, #0\n"
258         "       b       secondary_start_kernel"
259                 :
260                 : "r" (task_stack_page(current) + THREAD_SIZE - 8));
261 }
262 #endif /* CONFIG_HOTPLUG_CPU */
263 
264 int __cpu_logical_map[NR_CPUS];
265 
266 void __init smp_setup_processor_id(void)
267 {
268         int i;
269         u32 cpu = is_smp() ? read_cpuid_mpidr() & 0xff : 0;
270 
271         cpu_logical_map(0) = cpu;
272         for (i = 1; i < NR_CPUS; ++i)
273                 cpu_logical_map(i) = i == cpu ? 0 : i;
274 
275         printk(KERN_INFO "Booting Linux on physical CPU %d\n", cpu);
276 }
277 
278 /*
279  * Called by both boot and secondaries to move global data into
280  * per-processor storage.
281  */
282 static void __cpuinit smp_store_cpu_info(unsigned int cpuid)
283 {
284         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
285 
286         cpu_info->loops_per_jiffy = loops_per_jiffy;
287 
288         store_cpu_topology(cpuid);
289 }
290 
291 /*
292  * This is the secondary CPU boot entry.  We're using this CPUs
293  * idle thread stack, but a set of temporary page tables.
294  */
295 asmlinkage void __cpuinit secondary_start_kernel(void)
296 {
297         struct mm_struct *mm = &init_mm;
298         unsigned int cpu;
299 
300         /*
301          * The identity mapping is uncached (strongly ordered), so
302          * switch away from it before attempting any exclusive accesses.
303          */
304         cpu_switch_mm(mm->pgd, mm);
305         enter_lazy_tlb(mm, current);
306         local_flush_tlb_all();
307 
308         /*
309          * All kernel threads share the same mm context; grab a
310          * reference and switch to it.
311          */
312         cpu = smp_processor_id();
313         atomic_inc(&mm->mm_count);
314         current->active_mm = mm;
315         cpumask_set_cpu(cpu, mm_cpumask(mm));
316 
317         printk("CPU%u: Booted secondary processor\n", cpu);
318 
319         cpu_init();
320         preempt_disable();
321         trace_hardirqs_off();
322 
323         /*
324          * Give the platform a chance to do its own initialisation.
325          */
326         platform_secondary_init(cpu);
327 
328         notify_cpu_starting(cpu);
329 
330         calibrate_delay();
331 
332         smp_store_cpu_info(cpu);
333 
334         /*
335          * OK, now it's safe to let the boot CPU continue.  Wait for
336          * the CPU migration code to notice that the CPU is online
337          * before we continue.
338          */
339         set_cpu_online(cpu, true);
340 
341         /*
342          * Setup the percpu timer for this CPU.
343          */
344         percpu_timer_setup();
345 
346         while (!cpu_active(cpu))
347                 cpu_relax();
348 
349         /*
350          * cpu_active bit is set, so it's safe to enalbe interrupts
351          * now.
352          */
353         local_irq_enable();
354         local_fiq_enable();
355 
356         /*
357          * OK, it's off to the idle thread for us
358          */
359         cpu_idle();
360 }
361 
362 void __init smp_cpus_done(unsigned int max_cpus)
363 {
364         int cpu;
365         unsigned long bogosum = 0;
366 
367         for_each_online_cpu(cpu)
368                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
369 
370         printk(KERN_INFO "SMP: Total of %d processors activated "
371                "(%lu.%02lu BogoMIPS).\n",
372                num_online_cpus(),
373                bogosum / (500000/HZ),
374                (bogosum / (5000/HZ)) % 100);
375 }
376 
377 void __init smp_prepare_boot_cpu(void)
378 {
379         unsigned int cpu = smp_processor_id();
380 
381         per_cpu(cpu_data, cpu).idle = current;
382 }
383 
384 void __init smp_prepare_cpus(unsigned int max_cpus)
385 {
386         unsigned int ncores = num_possible_cpus();
387 
388         init_cpu_topology();
389 
390         smp_store_cpu_info(smp_processor_id());
391 
392         /*
393          * are we trying to boot more cores than exist?
394          */
395         if (max_cpus > ncores)
396                 max_cpus = ncores;
397         if (ncores > 1 && max_cpus) {
398                 /*
399                  * Enable the local timer or broadcast device for the
400                  * boot CPU, but only if we have more than one CPU.
401                  */
402                 percpu_timer_setup();
403 
404                 /*
405                  * Initialise the present map, which describes the set of CPUs
406                  * actually populated at the present time. A platform should
407                  * re-initialize the map in platform_smp_prepare_cpus() if
408                  * present != possible (e.g. physical hotplug).
409                  */
410                 init_cpu_present(&cpu_possible_map);
411 
412                 /*
413                  * Initialise the SCU if there are more than one CPU
414                  * and let them know where to start.
415                  */
416                 platform_smp_prepare_cpus(max_cpus);
417         }
418 }
419 
420 static void (*smp_cross_call)(const struct cpumask *, unsigned int);
421 
422 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
423 {
424         smp_cross_call = fn;
425 }
426 
427 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
428 {
429         smp_cross_call(mask, IPI_CALL_FUNC);
430 }
431 
432 void arch_send_call_function_single_ipi(int cpu)
433 {
434         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
435 }
436 
437 static const char *ipi_types[NR_IPI] = {
438 #define S(x,s)  [x - IPI_TIMER] = s
439         S(IPI_TIMER, "Timer broadcast interrupts"),
440         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
441         S(IPI_CALL_FUNC, "Function call interrupts"),
442         S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
443         S(IPI_CPU_STOP, "CPU stop interrupts"),
444 };
445 
446 void show_ipi_list(struct seq_file *p, int prec)
447 {
448         unsigned int cpu, i;
449 
450         for (i = 0; i < NR_IPI; i++) {
451                 seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
452 
453                 for_each_present_cpu(cpu)
454                         seq_printf(p, "%10u ",
455                                    __get_irq_stat(cpu, ipi_irqs[i]));
456 
457                 seq_printf(p, " %s\n", ipi_types[i]);
458         }
459 }
460 
461 u64 smp_irq_stat_cpu(unsigned int cpu)
462 {
463         u64 sum = 0;
464         int i;
465 
466         for (i = 0; i < NR_IPI; i++)
467                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
468 
469         return sum;
470 }
471 
472 /*
473  * Timer (local or broadcast) support
474  */
475 static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);
476 
477 static void ipi_timer(void)
478 {
479         struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
480         evt->event_handler(evt);
481 }
482 
483 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
484 static void smp_timer_broadcast(const struct cpumask *mask)
485 {
486         smp_cross_call(mask, IPI_TIMER);
487 }
488 #else
489 #define smp_timer_broadcast     NULL
490 #endif
491 
492 static void broadcast_timer_set_mode(enum clock_event_mode mode,
493         struct clock_event_device *evt)
494 {
495 }
496 
497 static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
498 {
499         evt->name       = "dummy_timer";
500         evt->features   = CLOCK_EVT_FEAT_ONESHOT |
501                           CLOCK_EVT_FEAT_PERIODIC |
502                           CLOCK_EVT_FEAT_DUMMY;
503         evt->rating     = 400;
504         evt->mult       = 1;
505         evt->set_mode   = broadcast_timer_set_mode;
506 
507         clockevents_register_device(evt);
508 }
509 
510 void __cpuinit percpu_timer_setup(void)
511 {
512         unsigned int cpu = smp_processor_id();
513         struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
514 
515         evt->cpumask = cpumask_of(cpu);
516         evt->broadcast = smp_timer_broadcast;
517 
518         if (local_timer_setup(evt))
519                 broadcast_timer_setup(evt);
520 }
521 
522 #ifdef CONFIG_HOTPLUG_CPU
523 /*
524  * The generic clock events code purposely does not stop the local timer
525  * on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
526  * manually here.
527  */
528 static void percpu_timer_stop(void)
529 {
530         unsigned int cpu = smp_processor_id();
531         struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
532 
533         local_timer_stop(evt);
534 }
535 #endif
536 
537 static DEFINE_RAW_SPINLOCK(stop_lock);
538 
539 /*
540  * ipi_cpu_stop - handle IPI from smp_send_stop()
541  */
542 static void ipi_cpu_stop(unsigned int cpu)
543 {
544         if (system_state == SYSTEM_BOOTING ||
545             system_state == SYSTEM_RUNNING) {
546                 raw_spin_lock(&stop_lock);
547                 printk(KERN_CRIT "CPU%u: stopping\n", cpu);
548                 dump_stack();
549                 raw_spin_unlock(&stop_lock);
550         }
551 
552         set_cpu_online(cpu, false);
553 
554         local_fiq_disable();
555         local_irq_disable();
556 
557         while (1)
558                 cpu_relax();
559 }
560 
561 /*
562  * Main handler for inter-processor interrupts
563  */
564 asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
565 {
566         handle_IPI(ipinr, regs);
567 }
568 
569 void handle_IPI(int ipinr, struct pt_regs *regs)
570 {
571         unsigned int cpu = smp_processor_id();
572         struct pt_regs *old_regs = set_irq_regs(regs);
573 
574         if (ipinr >= IPI_TIMER && ipinr < IPI_TIMER + NR_IPI)
575                 __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_TIMER]);
576 
577         switch (ipinr) {
578         case IPI_TIMER:
579                 irq_enter();
580                 ipi_timer();
581                 irq_exit();
582                 break;
583 
584         case IPI_RESCHEDULE:
585                 scheduler_ipi();
586                 break;
587 
588         case IPI_CALL_FUNC:
589                 irq_enter();
590                 generic_smp_call_function_interrupt();
591                 irq_exit();
592                 break;
593 
594         case IPI_CALL_FUNC_SINGLE:
595                 irq_enter();
596                 generic_smp_call_function_single_interrupt();
597                 irq_exit();
598                 break;
599 
600         case IPI_CPU_STOP:
601                 irq_enter();
602                 ipi_cpu_stop(cpu);
603                 irq_exit();
604                 break;
605 
606         default:
607                 printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
608                        cpu, ipinr);
609                 break;
610         }
611         set_irq_regs(old_regs);
612 }
613 
614 void smp_send_reschedule(int cpu)
615 {
616         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
617 }
618 
619 void smp_send_stop(void)
620 {
621         unsigned long timeout;
622 
623         if (num_online_cpus() > 1) {
624                 cpumask_t mask = cpu_online_map;
625                 cpu_clear(smp_processor_id(), mask);
626 
627                 smp_cross_call(&mask, IPI_CPU_STOP);
628         }
629 
630         /* Wait up to one second for other CPUs to stop */
631         timeout = USEC_PER_SEC;
632         while (num_online_cpus() > 1 && timeout--)
633                 udelay(1);
634 
635         if (num_online_cpus() > 1)
636                 pr_warning("SMP: failed to stop secondary CPUs\n");
637 }
638 
639 /*
640  * not supported here
641  */
642 int setup_profiling_timer(unsigned int multiplier)
643 {
644         return -EINVAL;
645 }
646 

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