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/atomic.h>
41 #include <asm/cacheflush.h>
43 #include <asm/cputype.h>
44 #include <asm/cpu_ops.h>
45 #include <asm/mmu_context.h>
46 #include <asm/pgtable.h>
47 #include <asm/pgalloc.h>
48 #include <asm/processor.h>
49 #include <asm/smp_plat.h>
50 #include <asm/sections.h>
51 #include <asm/tlbflush.h>
52 #include <asm/ptrace.h>
55 * as from 2.5, kernels no longer have an init_tasks structure
56 * so we need some other way of telling a new secondary core
57 * where to place its SVC stack
59 struct secondary_data secondary_data;
71 * Boot a secondary CPU, and assign it the specified idle task.
72 * This also gives us the initial stack to use for this CPU.
74 static int boot_secondary(unsigned int cpu, struct task_struct *idle)
76 if (cpu_ops[cpu]->cpu_boot)
77 return cpu_ops[cpu]->cpu_boot(cpu);
82 static DECLARE_COMPLETION(cpu_running);
84 int __cpu_up(unsigned int cpu, struct task_struct *idle)
89 * We need to tell the secondary core where to find its stack and the
92 secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
93 __flush_dcache_area(&secondary_data, sizeof(secondary_data));
96 * Now bring the CPU into our world.
98 ret = boot_secondary(cpu, idle);
101 * CPU was successfully started, wait for it to come online or
104 wait_for_completion_timeout(&cpu_running,
105 msecs_to_jiffies(1000));
107 if (!cpu_online(cpu)) {
108 pr_crit("CPU%u: failed to come online\n", cpu);
112 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
115 secondary_data.stack = NULL;
120 static void smp_store_cpu_info(unsigned int cpuid)
122 store_cpu_topology(cpuid);
126 * This is the secondary CPU boot entry. We're using this CPUs
127 * idle thread stack, but a set of temporary page tables.
129 asmlinkage void secondary_start_kernel(void)
131 struct mm_struct *mm = &init_mm;
132 unsigned int cpu = smp_processor_id();
135 * All kernel threads share the same mm context; grab a
136 * reference and switch to it.
138 atomic_inc(&mm->mm_count);
139 current->active_mm = mm;
140 cpumask_set_cpu(cpu, mm_cpumask(mm));
142 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
143 printk("CPU%u: Booted secondary processor\n", cpu);
146 * TTBR0 is only used for the identity mapping at this stage. Make it
147 * point to zero page to avoid speculatively fetching new entries.
149 cpu_set_reserved_ttbr0();
153 trace_hardirqs_off();
155 if (cpu_ops[cpu]->cpu_postboot)
156 cpu_ops[cpu]->cpu_postboot();
159 * Log the CPU info before it is marked online and might get read.
164 * Enable GIC and timers.
166 notify_cpu_starting(cpu);
168 smp_store_cpu_info(cpu);
171 * OK, now it's safe to let the boot CPU continue. Wait for
172 * the CPU migration code to notice that the CPU is online
173 * before we continue.
175 set_cpu_online(cpu, true);
176 complete(&cpu_running);
180 local_async_enable();
183 * OK, it's off to the idle thread for us
185 cpu_startup_entry(CPUHP_ONLINE);
188 #ifdef CONFIG_HOTPLUG_CPU
189 static int op_cpu_disable(unsigned int cpu)
192 * If we don't have a cpu_die method, abort before we reach the point
193 * of no return. CPU0 may not have an cpu_ops, so test for it.
195 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
199 * We may need to abort a hot unplug for some other mechanism-specific
202 if (cpu_ops[cpu]->cpu_disable)
203 return cpu_ops[cpu]->cpu_disable(cpu);
209 * __cpu_disable runs on the processor to be shutdown.
211 int __cpu_disable(void)
213 unsigned int cpu = smp_processor_id();
216 ret = op_cpu_disable(cpu);
221 * Take this CPU offline. Once we clear this, we can't return,
222 * and we must not schedule until we're ready to give up the cpu.
224 set_cpu_online(cpu, false);
227 * OK - migrate IRQs away from this CPU
232 * Remove this CPU from the vm mask set of all processes.
234 clear_tasks_mm_cpumask(cpu);
239 static int op_cpu_kill(unsigned int cpu)
242 * If we have no means of synchronising with the dying CPU, then assume
243 * that it is really dead. We can only wait for an arbitrary length of
244 * time and hope that it's dead, so let's skip the wait and just hope.
246 if (!cpu_ops[cpu]->cpu_kill)
249 return cpu_ops[cpu]->cpu_kill(cpu);
252 static DECLARE_COMPLETION(cpu_died);
255 * called on the thread which is asking for a CPU to be shutdown -
256 * waits until shutdown has completed, or it is timed out.
258 void __cpu_die(unsigned int cpu)
260 if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
261 pr_crit("CPU%u: cpu didn't die\n", cpu);
264 pr_notice("CPU%u: shutdown\n", cpu);
267 * Now that the dying CPU is beyond the point of no return w.r.t.
268 * in-kernel synchronisation, try to get the firwmare to help us to
269 * verify that it has really left the kernel before we consider
270 * clobbering anything it might still be using.
272 if (!op_cpu_kill(cpu))
273 pr_warn("CPU%d may not have shut down cleanly\n", cpu);
277 * Called from the idle thread for the CPU which has been shutdown.
279 * Note that we disable IRQs here, but do not re-enable them
280 * before returning to the caller. This is also the behaviour
281 * of the other hotplug-cpu capable cores, so presumably coming
282 * out of idle fixes this.
286 unsigned int cpu = smp_processor_id();
292 /* Tell __cpu_die() that this CPU is now safe to dispose of */
296 * Actually shutdown the CPU. This must never fail. The specific hotplug
297 * mechanism must perform all required cache maintenance to ensure that
298 * no dirty lines are lost in the process of shutting down the CPU.
300 cpu_ops[cpu]->cpu_die(cpu);
306 void __init smp_cpus_done(unsigned int max_cpus)
308 pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
311 void __init smp_prepare_boot_cpu(void)
313 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
316 static void (*smp_cross_call)(const struct cpumask *, unsigned int);
319 * Enumerate the possible CPU set from the device tree and build the
320 * cpu logical map array containing MPIDR values related to logical
321 * cpus. Assumes that cpu_logical_map(0) has already been initialized.
323 void __init smp_init_cpus(void)
325 struct device_node *dn = NULL;
326 unsigned int i, cpu = 1;
327 bool bootcpu_valid = false;
329 while ((dn = of_find_node_by_type(dn, "cpu"))) {
334 * A cpu node with missing "reg" property is
335 * considered invalid to build a cpu_logical_map
338 cell = of_get_property(dn, "reg", NULL);
340 pr_err("%s: missing reg property\n", dn->full_name);
343 hwid = of_read_number(cell, of_n_addr_cells(dn));
346 * Non affinity bits must be set to 0 in the DT
348 if (hwid & ~MPIDR_HWID_BITMASK) {
349 pr_err("%s: invalid reg property\n", dn->full_name);
354 * Duplicate MPIDRs are a recipe for disaster. Scan
355 * all initialized entries and check for
356 * duplicates. If any is found just ignore the cpu.
357 * cpu_logical_map was initialized to INVALID_HWID to
358 * avoid matching valid MPIDR values.
360 for (i = 1; (i < cpu) && (i < NR_CPUS); i++) {
361 if (cpu_logical_map(i) == hwid) {
362 pr_err("%s: duplicate cpu reg properties in the DT\n",
369 * The numbering scheme requires that the boot CPU
370 * must be assigned logical id 0. Record it so that
371 * the logical map built from DT is validated and can
374 if (hwid == cpu_logical_map(0)) {
376 pr_err("%s: duplicate boot cpu reg property in DT\n",
381 bootcpu_valid = true;
384 * cpu_logical_map has already been
385 * initialized and the boot cpu doesn't need
386 * the enable-method so continue without
395 if (cpu_read_ops(dn, cpu) != 0)
398 if (cpu_ops[cpu]->cpu_init(dn, cpu))
401 pr_debug("cpu logical map 0x%llx\n", hwid);
402 cpu_logical_map(cpu) = hwid;
409 pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
412 if (!bootcpu_valid) {
413 pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
418 * All the cpus that made it to the cpu_logical_map have been
419 * validated so set them as possible cpus.
421 for (i = 0; i < NR_CPUS; i++)
422 if (cpu_logical_map(i) != INVALID_HWID)
423 set_cpu_possible(i, true);
426 void __init smp_prepare_cpus(unsigned int max_cpus)
429 unsigned int cpu, ncores = num_possible_cpus();
433 smp_store_cpu_info(smp_processor_id());
436 * are we trying to boot more cores than exist?
438 if (max_cpus > ncores)
441 /* Don't bother if we're effectively UP */
446 * Initialise the present map (which describes the set of CPUs
447 * actually populated at the present time) and release the
448 * secondaries from the bootloader.
450 * Make sure we online at most (max_cpus - 1) additional CPUs.
453 for_each_possible_cpu(cpu) {
457 if (cpu == smp_processor_id())
463 err = cpu_ops[cpu]->cpu_prepare(cpu);
467 set_cpu_present(cpu, true);
473 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
478 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
480 smp_cross_call(mask, IPI_CALL_FUNC);
483 void arch_send_call_function_single_ipi(int cpu)
485 smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
488 #ifdef CONFIG_IRQ_WORK
489 void arch_irq_work_raise(void)
492 smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
496 static const char *ipi_types[NR_IPI] = {
497 #define S(x,s) [x - IPI_RESCHEDULE] = s
498 S(IPI_RESCHEDULE, "Rescheduling interrupts"),
499 S(IPI_CALL_FUNC, "Function call interrupts"),
500 S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
501 S(IPI_CPU_STOP, "CPU stop interrupts"),
502 S(IPI_TIMER, "Timer broadcast interrupts"),
503 S(IPI_IRQ_WORK, "IRQ work interrupts"),
506 void show_ipi_list(struct seq_file *p, int prec)
510 for (i = 0; i < NR_IPI; i++) {
511 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i + IPI_RESCHEDULE,
512 prec >= 4 ? " " : "");
513 for_each_online_cpu(cpu)
514 seq_printf(p, "%10u ",
515 __get_irq_stat(cpu, ipi_irqs[i]));
516 seq_printf(p, " %s\n", ipi_types[i]);
520 u64 smp_irq_stat_cpu(unsigned int cpu)
525 for (i = 0; i < NR_IPI; i++)
526 sum += __get_irq_stat(cpu, ipi_irqs[i]);
531 static DEFINE_RAW_SPINLOCK(stop_lock);
534 * ipi_cpu_stop - handle IPI from smp_send_stop()
536 static void ipi_cpu_stop(unsigned int cpu)
538 if (system_state == SYSTEM_BOOTING ||
539 system_state == SYSTEM_RUNNING) {
540 raw_spin_lock(&stop_lock);
541 pr_crit("CPU%u: stopping\n", cpu);
543 raw_spin_unlock(&stop_lock);
546 set_cpu_online(cpu, false);
555 * Main handler for inter-processor interrupts
557 void handle_IPI(int ipinr, struct pt_regs *regs)
559 unsigned int cpu = smp_processor_id();
560 struct pt_regs *old_regs = set_irq_regs(regs);
562 if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
563 __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
572 generic_smp_call_function_interrupt();
576 case IPI_CALL_FUNC_SINGLE:
578 generic_smp_call_function_single_interrupt();
588 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
591 tick_receive_broadcast();
596 #ifdef CONFIG_IRQ_WORK
605 pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
608 set_irq_regs(old_regs);
611 void smp_send_reschedule(int cpu)
613 smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
616 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
617 void tick_broadcast(const struct cpumask *mask)
619 smp_cross_call(mask, IPI_TIMER);
623 void smp_send_stop(void)
625 unsigned long timeout;
627 if (num_online_cpus() > 1) {
630 cpumask_copy(&mask, cpu_online_mask);
631 cpu_clear(smp_processor_id(), mask);
633 smp_cross_call(&mask, IPI_CPU_STOP);
636 /* Wait up to one second for other CPUs to stop */
637 timeout = USEC_PER_SEC;
638 while (num_online_cpus() > 1 && timeout--)
641 if (num_online_cpus() > 1)
642 pr_warning("SMP: failed to stop secondary CPUs\n");
648 int setup_profiling_timer(unsigned int multiplier)