2 * SMP initialisation and IPI support
3 * Based on arch/arm/kernel/smp.c
5 * Copyright (C) 2012 ARM Ltd.
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.
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.
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/>.
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>
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>
38 #include <linux/irq_work.h>
40 #include <asm/alternative.h>
41 #include <asm/atomic.h>
42 #include <asm/cacheflush.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>
55 #define CREATE_TRACE_POINTS
56 #include <trace/events/ipi.h>
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
63 struct secondary_data secondary_data;
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.
77 static int boot_secondary(unsigned int cpu, struct task_struct *idle)
79 if (cpu_ops[cpu]->cpu_boot)
80 return cpu_ops[cpu]->cpu_boot(cpu);
85 static DECLARE_COMPLETION(cpu_running);
87 int __cpu_up(unsigned int cpu, struct task_struct *idle)
92 * We need to tell the secondary core where to find its stack and the
95 secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
96 __flush_dcache_area(&secondary_data, sizeof(secondary_data));
99 * Now bring the CPU into our world.
101 ret = boot_secondary(cpu, idle);
104 * CPU was successfully started, wait for it to come online or
107 wait_for_completion_timeout(&cpu_running,
108 msecs_to_jiffies(1000));
110 if (!cpu_online(cpu)) {
111 pr_crit("CPU%u: failed to come online\n", cpu);
115 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
118 secondary_data.stack = NULL;
123 static void smp_store_cpu_info(unsigned int cpuid)
125 store_cpu_topology(cpuid);
129 * This is the secondary CPU boot entry. We're using this CPUs
130 * idle thread stack, but a set of temporary page tables.
132 asmlinkage void secondary_start_kernel(void)
134 struct mm_struct *mm = &init_mm;
135 unsigned int cpu = smp_processor_id();
138 * All kernel threads share the same mm context; grab a
139 * reference and switch to it.
141 atomic_inc(&mm->mm_count);
142 current->active_mm = mm;
143 cpumask_set_cpu(cpu, mm_cpumask(mm));
145 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
146 printk("CPU%u: Booted secondary processor\n", cpu);
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.
152 cpu_set_reserved_ttbr0();
156 trace_hardirqs_off();
158 if (cpu_ops[cpu]->cpu_postboot)
159 cpu_ops[cpu]->cpu_postboot();
162 * Log the CPU info before it is marked online and might get read.
167 * Enable GIC and timers.
169 notify_cpu_starting(cpu);
171 smp_store_cpu_info(cpu);
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.
178 set_cpu_online(cpu, true);
179 complete(&cpu_running);
183 local_async_enable();
186 * OK, it's off to the idle thread for us
188 cpu_startup_entry(CPUHP_ONLINE);
191 #ifdef CONFIG_HOTPLUG_CPU
192 static int op_cpu_disable(unsigned int cpu)
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.
198 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
202 * We may need to abort a hot unplug for some other mechanism-specific
205 if (cpu_ops[cpu]->cpu_disable)
206 return cpu_ops[cpu]->cpu_disable(cpu);
212 * __cpu_disable runs on the processor to be shutdown.
214 int __cpu_disable(void)
216 unsigned int cpu = smp_processor_id();
219 ret = op_cpu_disable(cpu);
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.
227 set_cpu_online(cpu, false);
230 * OK - migrate IRQs away from this CPU
235 * Remove this CPU from the vm mask set of all processes.
237 clear_tasks_mm_cpumask(cpu);
242 static int op_cpu_kill(unsigned int cpu)
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.
249 if (!cpu_ops[cpu]->cpu_kill)
252 return cpu_ops[cpu]->cpu_kill(cpu);
255 static DECLARE_COMPLETION(cpu_died);
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.
261 void __cpu_die(unsigned int cpu)
263 if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
264 pr_crit("CPU%u: cpu didn't die\n", cpu);
267 pr_notice("CPU%u: shutdown\n", cpu);
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.
275 if (!op_cpu_kill(cpu))
276 pr_warn("CPU%d may not have shut down cleanly\n", cpu);
280 * Called from the idle thread for the CPU which has been shutdown.
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.
289 unsigned int cpu = smp_processor_id();
295 /* Tell __cpu_die() that this CPU is now safe to dispose of */
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.
303 cpu_ops[cpu]->cpu_die(cpu);
309 void __init smp_cpus_done(unsigned int max_cpus)
311 pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
312 apply_alternatives_all();
315 void __init smp_prepare_boot_cpu(void)
317 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
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.
325 void __init smp_init_cpus(void)
327 struct device_node *dn = NULL;
328 unsigned int i, cpu = 1;
329 bool bootcpu_valid = false;
331 while ((dn = of_find_node_by_type(dn, "cpu"))) {
336 * A cpu node with missing "reg" property is
337 * considered invalid to build a cpu_logical_map
340 cell = of_get_property(dn, "reg", NULL);
342 pr_err("%s: missing reg property\n", dn->full_name);
345 hwid = of_read_number(cell, of_n_addr_cells(dn));
348 * Non affinity bits must be set to 0 in the DT
350 if (hwid & ~MPIDR_HWID_BITMASK) {
351 pr_err("%s: invalid reg property\n", dn->full_name);
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.
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",
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
376 if (hwid == cpu_logical_map(0)) {
378 pr_err("%s: duplicate boot cpu reg property in DT\n",
383 bootcpu_valid = true;
386 * cpu_logical_map has already been
387 * initialized and the boot cpu doesn't need
388 * the enable-method so continue without
397 if (cpu_read_ops(dn, cpu) != 0)
400 if (cpu_ops[cpu]->cpu_init(dn, cpu))
403 pr_debug("cpu logical map 0x%llx\n", hwid);
404 cpu_logical_map(cpu) = hwid;
411 pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
414 if (!bootcpu_valid) {
415 pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
420 * All the cpus that made it to the cpu_logical_map have been
421 * validated so set them as possible cpus.
423 for (i = 0; i < NR_CPUS; i++)
424 if (cpu_logical_map(i) != INVALID_HWID)
425 set_cpu_possible(i, true);
428 void __init smp_prepare_cpus(unsigned int max_cpus)
431 unsigned int cpu, ncores = num_possible_cpus();
435 smp_store_cpu_info(smp_processor_id());
438 * are we trying to boot more cores than exist?
440 if (max_cpus > ncores)
443 /* Don't bother if we're effectively UP */
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.
452 * Make sure we online at most (max_cpus - 1) additional CPUs.
455 for_each_possible_cpu(cpu) {
459 if (cpu == smp_processor_id())
465 err = cpu_ops[cpu]->cpu_prepare(cpu);
469 set_cpu_present(cpu, true);
474 void (*__smp_cross_call)(const struct cpumask *, unsigned int);
476 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
478 __smp_cross_call = fn;
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"),
490 static void smp_cross_call(const struct cpumask *target, unsigned int ipinr)
492 trace_ipi_raise(target, ipi_types[ipinr]);
493 __smp_cross_call(target, ipinr);
496 void show_ipi_list(struct seq_file *p, int prec)
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]);
510 u64 smp_irq_stat_cpu(unsigned int cpu)
515 for (i = 0; i < NR_IPI; i++)
516 sum += __get_irq_stat(cpu, ipi_irqs[i]);
521 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
523 smp_cross_call(mask, IPI_CALL_FUNC);
526 void arch_send_call_function_single_ipi(int cpu)
528 smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
531 #ifdef CONFIG_IRQ_WORK
532 void arch_irq_work_raise(void)
534 if (__smp_cross_call)
535 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
539 static DEFINE_RAW_SPINLOCK(stop_lock);
542 * ipi_cpu_stop - handle IPI from smp_send_stop()
544 static void ipi_cpu_stop(unsigned int cpu)
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);
551 raw_spin_unlock(&stop_lock);
554 set_cpu_online(cpu, false);
563 * Main handler for inter-processor interrupts
565 void handle_IPI(int ipinr, struct pt_regs *regs)
567 unsigned int cpu = smp_processor_id();
568 struct pt_regs *old_regs = set_irq_regs(regs);
570 if ((unsigned)ipinr < NR_IPI) {
571 trace_ipi_entry(ipi_types[ipinr]);
572 __inc_irq_stat(cpu, ipi_irqs[ipinr]);
582 generic_smp_call_function_interrupt();
592 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
595 tick_receive_broadcast();
600 #ifdef CONFIG_IRQ_WORK
609 pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
613 if ((unsigned)ipinr < NR_IPI)
614 trace_ipi_exit(ipi_types[ipinr]);
615 set_irq_regs(old_regs);
618 void smp_send_reschedule(int cpu)
620 smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
623 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
624 void tick_broadcast(const struct cpumask *mask)
626 smp_cross_call(mask, IPI_TIMER);
630 void smp_send_stop(void)
632 unsigned long timeout;
634 if (num_online_cpus() > 1) {
637 cpumask_copy(&mask, cpu_online_mask);
638 cpu_clear(smp_processor_id(), mask);
640 smp_cross_call(&mask, IPI_CPU_STOP);
643 /* Wait up to one second for other CPUs to stop */
644 timeout = USEC_PER_SEC;
645 while (num_online_cpus() > 1 && timeout--)
648 if (num_online_cpus() > 1)
649 pr_warning("SMP: failed to stop secondary CPUs\n");
655 int setup_profiling_timer(unsigned int multiplier)