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Linux/arch/arm64/kernel/smp.c

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  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/delay.h>
 21 #include <linux/init.h>
 22 #include <linux/spinlock.h>
 23 #include <linux/sched.h>
 24 #include <linux/interrupt.h>
 25 #include <linux/cache.h>
 26 #include <linux/profile.h>
 27 #include <linux/errno.h>
 28 #include <linux/mm.h>
 29 #include <linux/err.h>
 30 #include <linux/cpu.h>
 31 #include <linux/smp.h>
 32 #include <linux/seq_file.h>
 33 #include <linux/irq.h>
 34 #include <linux/percpu.h>
 35 #include <linux/clockchips.h>
 36 #include <linux/completion.h>
 37 #include <linux/of.h>
 38 #include <linux/irq_work.h>
 39 
 40 #include <asm/alternative.h>
 41 #include <asm/atomic.h>
 42 #include <asm/cacheflush.h>
 43 #include <asm/cpu.h>
 44 #include <asm/cputype.h>
 45 #include <asm/cpu_ops.h>
 46 #include <asm/mmu_context.h>
 47 #include <asm/pgtable.h>
 48 #include <asm/pgalloc.h>
 49 #include <asm/processor.h>
 50 #include <asm/smp_plat.h>
 51 #include <asm/sections.h>
 52 #include <asm/tlbflush.h>
 53 #include <asm/ptrace.h>
 54 
 55 #define CREATE_TRACE_POINTS
 56 #include <trace/events/ipi.h>
 57 
 58 /*
 59  * as from 2.5, kernels no longer have an init_tasks structure
 60  * so we need some other way of telling a new secondary core
 61  * where to place its SVC stack
 62  */
 63 struct secondary_data secondary_data;
 64 
 65 enum ipi_msg_type {
 66         IPI_RESCHEDULE,
 67         IPI_CALL_FUNC,
 68         IPI_CPU_STOP,
 69         IPI_TIMER,
 70         IPI_IRQ_WORK,
 71 };
 72 
 73 /*
 74  * Boot a secondary CPU, and assign it the specified idle task.
 75  * This also gives us the initial stack to use for this CPU.
 76  */
 77 static int boot_secondary(unsigned int cpu, struct task_struct *idle)
 78 {
 79         if (cpu_ops[cpu]->cpu_boot)
 80                 return cpu_ops[cpu]->cpu_boot(cpu);
 81 
 82         return -EOPNOTSUPP;
 83 }
 84 
 85 static DECLARE_COMPLETION(cpu_running);
 86 
 87 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 88 {
 89         int ret;
 90 
 91         /*
 92          * We need to tell the secondary core where to find its stack and the
 93          * page tables.
 94          */
 95         secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
 96         __flush_dcache_area(&secondary_data, sizeof(secondary_data));
 97 
 98         /*
 99          * Now bring the CPU into our world.
100          */
101         ret = boot_secondary(cpu, idle);
102         if (ret == 0) {
103                 /*
104                  * CPU was successfully started, wait for it to come online or
105                  * time out.
106                  */
107                 wait_for_completion_timeout(&cpu_running,
108                                             msecs_to_jiffies(1000));
109 
110                 if (!cpu_online(cpu)) {
111                         pr_crit("CPU%u: failed to come online\n", cpu);
112                         ret = -EIO;
113                 }
114         } else {
115                 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
116         }
117 
118         secondary_data.stack = NULL;
119 
120         return ret;
121 }
122 
123 static void smp_store_cpu_info(unsigned int cpuid)
124 {
125         store_cpu_topology(cpuid);
126 }
127 
128 /*
129  * This is the secondary CPU boot entry.  We're using this CPUs
130  * idle thread stack, but a set of temporary page tables.
131  */
132 asmlinkage void secondary_start_kernel(void)
133 {
134         struct mm_struct *mm = &init_mm;
135         unsigned int cpu = smp_processor_id();
136 
137         /*
138          * All kernel threads share the same mm context; grab a
139          * reference and switch to it.
140          */
141         atomic_inc(&mm->mm_count);
142         current->active_mm = mm;
143         cpumask_set_cpu(cpu, mm_cpumask(mm));
144 
145         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
146         printk("CPU%u: Booted secondary processor\n", cpu);
147 
148         /*
149          * TTBR0 is only used for the identity mapping at this stage. Make it
150          * point to zero page to avoid speculatively fetching new entries.
151          */
152         cpu_set_reserved_ttbr0();
153         flush_tlb_all();
154 
155         preempt_disable();
156         trace_hardirqs_off();
157 
158         if (cpu_ops[cpu]->cpu_postboot)
159                 cpu_ops[cpu]->cpu_postboot();
160 
161         /*
162          * Log the CPU info before it is marked online and might get read.
163          */
164         cpuinfo_store_cpu();
165 
166         /*
167          * Enable GIC and timers.
168          */
169         notify_cpu_starting(cpu);
170 
171         smp_store_cpu_info(cpu);
172 
173         /*
174          * OK, now it's safe to let the boot CPU continue.  Wait for
175          * the CPU migration code to notice that the CPU is online
176          * before we continue.
177          */
178         set_cpu_online(cpu, true);
179         complete(&cpu_running);
180 
181         local_dbg_enable();
182         local_irq_enable();
183         local_async_enable();
184 
185         /*
186          * OK, it's off to the idle thread for us
187          */
188         cpu_startup_entry(CPUHP_ONLINE);
189 }
190 
191 #ifdef CONFIG_HOTPLUG_CPU
192 static int op_cpu_disable(unsigned int cpu)
193 {
194         /*
195          * If we don't have a cpu_die method, abort before we reach the point
196          * of no return. CPU0 may not have an cpu_ops, so test for it.
197          */
198         if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
199                 return -EOPNOTSUPP;
200 
201         /*
202          * We may need to abort a hot unplug for some other mechanism-specific
203          * reason.
204          */
205         if (cpu_ops[cpu]->cpu_disable)
206                 return cpu_ops[cpu]->cpu_disable(cpu);
207 
208         return 0;
209 }
210 
211 /*
212  * __cpu_disable runs on the processor to be shutdown.
213  */
214 int __cpu_disable(void)
215 {
216         unsigned int cpu = smp_processor_id();
217         int ret;
218 
219         ret = op_cpu_disable(cpu);
220         if (ret)
221                 return ret;
222 
223         /*
224          * Take this CPU offline.  Once we clear this, we can't return,
225          * and we must not schedule until we're ready to give up the cpu.
226          */
227         set_cpu_online(cpu, false);
228 
229         /*
230          * OK - migrate IRQs away from this CPU
231          */
232         migrate_irqs();
233 
234         /*
235          * Remove this CPU from the vm mask set of all processes.
236          */
237         clear_tasks_mm_cpumask(cpu);
238 
239         return 0;
240 }
241 
242 static int op_cpu_kill(unsigned int cpu)
243 {
244         /*
245          * If we have no means of synchronising with the dying CPU, then assume
246          * that it is really dead. We can only wait for an arbitrary length of
247          * time and hope that it's dead, so let's skip the wait and just hope.
248          */
249         if (!cpu_ops[cpu]->cpu_kill)
250                 return 1;
251 
252         return cpu_ops[cpu]->cpu_kill(cpu);
253 }
254 
255 static DECLARE_COMPLETION(cpu_died);
256 
257 /*
258  * called on the thread which is asking for a CPU to be shutdown -
259  * waits until shutdown has completed, or it is timed out.
260  */
261 void __cpu_die(unsigned int cpu)
262 {
263         if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
264                 pr_crit("CPU%u: cpu didn't die\n", cpu);
265                 return;
266         }
267         pr_notice("CPU%u: shutdown\n", cpu);
268 
269         /*
270          * Now that the dying CPU is beyond the point of no return w.r.t.
271          * in-kernel synchronisation, try to get the firwmare to help us to
272          * verify that it has really left the kernel before we consider
273          * clobbering anything it might still be using.
274          */
275         if (!op_cpu_kill(cpu))
276                 pr_warn("CPU%d may not have shut down cleanly\n", cpu);
277 }
278 
279 /*
280  * Called from the idle thread for the CPU which has been shutdown.
281  *
282  * Note that we disable IRQs here, but do not re-enable them
283  * before returning to the caller. This is also the behaviour
284  * of the other hotplug-cpu capable cores, so presumably coming
285  * out of idle fixes this.
286  */
287 void cpu_die(void)
288 {
289         unsigned int cpu = smp_processor_id();
290 
291         idle_task_exit();
292 
293         local_irq_disable();
294 
295         /* Tell __cpu_die() that this CPU is now safe to dispose of */
296         complete(&cpu_died);
297 
298         /*
299          * Actually shutdown the CPU. This must never fail. The specific hotplug
300          * mechanism must perform all required cache maintenance to ensure that
301          * no dirty lines are lost in the process of shutting down the CPU.
302          */
303         cpu_ops[cpu]->cpu_die(cpu);
304 
305         BUG();
306 }
307 #endif
308 
309 void __init smp_cpus_done(unsigned int max_cpus)
310 {
311         pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
312         do_post_cpus_up_work();
313 }
314 
315 void __init smp_prepare_boot_cpu(void)
316 {
317         set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
318 }
319 
320 /*
321  * Enumerate the possible CPU set from the device tree and build the
322  * cpu logical map array containing MPIDR values related to logical
323  * cpus. Assumes that cpu_logical_map(0) has already been initialized.
324  */
325 void __init smp_init_cpus(void)
326 {
327         struct device_node *dn = NULL;
328         unsigned int i, cpu = 1;
329         bool bootcpu_valid = false;
330 
331         while ((dn = of_find_node_by_type(dn, "cpu"))) {
332                 const u32 *cell;
333                 u64 hwid;
334 
335                 /*
336                  * A cpu node with missing "reg" property is
337                  * considered invalid to build a cpu_logical_map
338                  * entry.
339                  */
340                 cell = of_get_property(dn, "reg", NULL);
341                 if (!cell) {
342                         pr_err("%s: missing reg property\n", dn->full_name);
343                         goto next;
344                 }
345                 hwid = of_read_number(cell, of_n_addr_cells(dn));
346 
347                 /*
348                  * Non affinity bits must be set to 0 in the DT
349                  */
350                 if (hwid & ~MPIDR_HWID_BITMASK) {
351                         pr_err("%s: invalid reg property\n", dn->full_name);
352                         goto next;
353                 }
354 
355                 /*
356                  * Duplicate MPIDRs are a recipe for disaster. Scan
357                  * all initialized entries and check for
358                  * duplicates. If any is found just ignore the cpu.
359                  * cpu_logical_map was initialized to INVALID_HWID to
360                  * avoid matching valid MPIDR values.
361                  */
362                 for (i = 1; (i < cpu) && (i < NR_CPUS); i++) {
363                         if (cpu_logical_map(i) == hwid) {
364                                 pr_err("%s: duplicate cpu reg properties in the DT\n",
365                                         dn->full_name);
366                                 goto next;
367                         }
368                 }
369 
370                 /*
371                  * The numbering scheme requires that the boot CPU
372                  * must be assigned logical id 0. Record it so that
373                  * the logical map built from DT is validated and can
374                  * be used.
375                  */
376                 if (hwid == cpu_logical_map(0)) {
377                         if (bootcpu_valid) {
378                                 pr_err("%s: duplicate boot cpu reg property in DT\n",
379                                         dn->full_name);
380                                 goto next;
381                         }
382 
383                         bootcpu_valid = true;
384 
385                         /*
386                          * cpu_logical_map has already been
387                          * initialized and the boot cpu doesn't need
388                          * the enable-method so continue without
389                          * incrementing cpu.
390                          */
391                         continue;
392                 }
393 
394                 if (cpu >= NR_CPUS)
395                         goto next;
396 
397                 if (cpu_read_ops(dn, cpu) != 0)
398                         goto next;
399 
400                 if (cpu_ops[cpu]->cpu_init(dn, cpu))
401                         goto next;
402 
403                 pr_debug("cpu logical map 0x%llx\n", hwid);
404                 cpu_logical_map(cpu) = hwid;
405 next:
406                 cpu++;
407         }
408 
409         /* sanity check */
410         if (cpu > NR_CPUS)
411                 pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
412                            cpu, NR_CPUS);
413 
414         if (!bootcpu_valid) {
415                 pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
416                 return;
417         }
418 
419         /*
420          * All the cpus that made it to the cpu_logical_map have been
421          * validated so set them as possible cpus.
422          */
423         for (i = 0; i < NR_CPUS; i++)
424                 if (cpu_logical_map(i) != INVALID_HWID)
425                         set_cpu_possible(i, true);
426 }
427 
428 void __init smp_prepare_cpus(unsigned int max_cpus)
429 {
430         int err;
431         unsigned int cpu, ncores = num_possible_cpus();
432 
433         init_cpu_topology();
434 
435         smp_store_cpu_info(smp_processor_id());
436 
437         /*
438          * are we trying to boot more cores than exist?
439          */
440         if (max_cpus > ncores)
441                 max_cpus = ncores;
442 
443         /* Don't bother if we're effectively UP */
444         if (max_cpus <= 1)
445                 return;
446 
447         /*
448          * Initialise the present map (which describes the set of CPUs
449          * actually populated at the present time) and release the
450          * secondaries from the bootloader.
451          *
452          * Make sure we online at most (max_cpus - 1) additional CPUs.
453          */
454         max_cpus--;
455         for_each_possible_cpu(cpu) {
456                 if (max_cpus == 0)
457                         break;
458 
459                 if (cpu == smp_processor_id())
460                         continue;
461 
462                 if (!cpu_ops[cpu])
463                         continue;
464 
465                 err = cpu_ops[cpu]->cpu_prepare(cpu);
466                 if (err)
467                         continue;
468 
469                 set_cpu_present(cpu, true);
470                 max_cpus--;
471         }
472 }
473 
474 void (*__smp_cross_call)(const struct cpumask *, unsigned int);
475 
476 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
477 {
478         __smp_cross_call = fn;
479 }
480 
481 static const char *ipi_types[NR_IPI] __tracepoint_string = {
482 #define S(x,s)  [x] = s
483         S(IPI_RESCHEDULE, "Rescheduling interrupts"),
484         S(IPI_CALL_FUNC, "Function call interrupts"),
485         S(IPI_CPU_STOP, "CPU stop interrupts"),
486         S(IPI_TIMER, "Timer broadcast interrupts"),
487         S(IPI_IRQ_WORK, "IRQ work interrupts"),
488 };
489 
490 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
491 {
492         trace_ipi_raise(target, ipi_types[ipinr]);
493         __smp_cross_call(target, ipinr);
494 }
495 
496 void show_ipi_list(struct seq_file *p, int prec)
497 {
498         unsigned int cpu, i;
499 
500         for (i = 0; i < NR_IPI; i++) {
501                 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
502                            prec >= 4 ? " " : "");
503                 for_each_online_cpu(cpu)
504                         seq_printf(p, "%10u ",
505                                    __get_irq_stat(cpu, ipi_irqs[i]));
506                 seq_printf(p, "      %s\n", ipi_types[i]);
507         }
508 }
509 
510 u64 smp_irq_stat_cpu(unsigned int cpu)
511 {
512         u64 sum = 0;
513         int i;
514 
515         for (i = 0; i < NR_IPI; i++)
516                 sum += __get_irq_stat(cpu, ipi_irqs[i]);
517 
518         return sum;
519 }
520 
521 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
522 {
523         smp_cross_call(mask, IPI_CALL_FUNC);
524 }
525 
526 void arch_send_call_function_single_ipi(int cpu)
527 {
528         smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
529 }
530 
531 #ifdef CONFIG_IRQ_WORK
532 void arch_irq_work_raise(void)
533 {
534         if (__smp_cross_call)
535                 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
536 }
537 #endif
538 
539 static DEFINE_RAW_SPINLOCK(stop_lock);
540 
541 /*
542  * ipi_cpu_stop - handle IPI from smp_send_stop()
543  */
544 static void ipi_cpu_stop(unsigned int cpu)
545 {
546         if (system_state == SYSTEM_BOOTING ||
547             system_state == SYSTEM_RUNNING) {
548                 raw_spin_lock(&stop_lock);
549                 pr_crit("CPU%u: stopping\n", cpu);
550                 dump_stack();
551                 raw_spin_unlock(&stop_lock);
552         }
553 
554         set_cpu_online(cpu, false);
555 
556         local_irq_disable();
557 
558         while (1)
559                 cpu_relax();
560 }
561 
562 /*
563  * Main handler for inter-processor interrupts
564  */
565 void handle_IPI(int ipinr, struct pt_regs *regs)
566 {
567         unsigned int cpu = smp_processor_id();
568         struct pt_regs *old_regs = set_irq_regs(regs);
569 
570         if ((unsigned)ipinr < NR_IPI) {
571                 trace_ipi_entry(ipi_types[ipinr]);
572                 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
573         }
574 
575         switch (ipinr) {
576         case IPI_RESCHEDULE:
577                 scheduler_ipi();
578                 break;
579 
580         case IPI_CALL_FUNC:
581                 irq_enter();
582                 generic_smp_call_function_interrupt();
583                 irq_exit();
584                 break;
585 
586         case IPI_CPU_STOP:
587                 irq_enter();
588                 ipi_cpu_stop(cpu);
589                 irq_exit();
590                 break;
591 
592 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
593         case IPI_TIMER:
594                 irq_enter();
595                 tick_receive_broadcast();
596                 irq_exit();
597                 break;
598 #endif
599 
600 #ifdef CONFIG_IRQ_WORK
601         case IPI_IRQ_WORK:
602                 irq_enter();
603                 irq_work_run();
604                 irq_exit();
605                 break;
606 #endif
607 
608         default:
609                 pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
610                 break;
611         }
612 
613         if ((unsigned)ipinr < NR_IPI)
614                 trace_ipi_exit(ipi_types[ipinr]);
615         set_irq_regs(old_regs);
616 }
617 
618 void smp_send_reschedule(int cpu)
619 {
620         smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
621 }
622 
623 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
624 void tick_broadcast(const struct cpumask *mask)
625 {
626         smp_cross_call(mask, IPI_TIMER);
627 }
628 #endif
629 
630 void smp_send_stop(void)
631 {
632         unsigned long timeout;
633 
634         if (num_online_cpus() > 1) {
635                 cpumask_t mask;
636 
637                 cpumask_copy(&mask, cpu_online_mask);
638                 cpu_clear(smp_processor_id(), mask);
639 
640                 smp_cross_call(&mask, IPI_CPU_STOP);
641         }
642 
643         /* Wait up to one second for other CPUs to stop */
644         timeout = USEC_PER_SEC;
645         while (num_online_cpus() > 1 && timeout--)
646                 udelay(1);
647 
648         if (num_online_cpus() > 1)
649                 pr_warning("SMP: failed to stop secondary CPUs\n");
650 }
651 
652 /*
653  * not supported here
654  */
655 int setup_profiling_timer(unsigned int multiplier)
656 {
657         return -EINVAL;
658 }
659 

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