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>
39 #include <asm/atomic.h>
40 #include <asm/cacheflush.h>
41 #include <asm/cputype.h>
42 #include <asm/cpu_ops.h>
43 #include <asm/mmu_context.h>
44 #include <asm/pgtable.h>
45 #include <asm/pgalloc.h>
46 #include <asm/processor.h>
47 #include <asm/smp_plat.h>
48 #include <asm/sections.h>
49 #include <asm/tlbflush.h>
50 #include <asm/ptrace.h>
53 * as from 2.5, kernels no longer have an init_tasks structure
54 * so we need some other way of telling a new secondary core
55 * where to place its SVC stack
57 struct secondary_data secondary_data;
68 * Boot a secondary CPU, and assign it the specified idle task.
69 * This also gives us the initial stack to use for this CPU.
71 static int boot_secondary(unsigned int cpu, struct task_struct *idle)
73 if (cpu_ops[cpu]->cpu_boot)
74 return cpu_ops[cpu]->cpu_boot(cpu);
79 static DECLARE_COMPLETION(cpu_running);
81 int __cpu_up(unsigned int cpu, struct task_struct *idle)
86 * We need to tell the secondary core where to find its stack and the
89 secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
90 __flush_dcache_area(&secondary_data, sizeof(secondary_data));
93 * Now bring the CPU into our world.
95 ret = boot_secondary(cpu, idle);
98 * CPU was successfully started, wait for it to come online or
101 wait_for_completion_timeout(&cpu_running,
102 msecs_to_jiffies(1000));
104 if (!cpu_online(cpu)) {
105 pr_crit("CPU%u: failed to come online\n", cpu);
109 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
112 secondary_data.stack = NULL;
117 static void smp_store_cpu_info(unsigned int cpuid)
119 store_cpu_topology(cpuid);
123 * This is the secondary CPU boot entry. We're using this CPUs
124 * idle thread stack, but a set of temporary page tables.
126 asmlinkage void secondary_start_kernel(void)
128 struct mm_struct *mm = &init_mm;
129 unsigned int cpu = smp_processor_id();
132 * All kernel threads share the same mm context; grab a
133 * reference and switch to it.
135 atomic_inc(&mm->mm_count);
136 current->active_mm = mm;
137 cpumask_set_cpu(cpu, mm_cpumask(mm));
139 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
140 printk("CPU%u: Booted secondary processor\n", cpu);
143 * TTBR0 is only used for the identity mapping at this stage. Make it
144 * point to zero page to avoid speculatively fetching new entries.
146 cpu_set_reserved_ttbr0();
150 trace_hardirqs_off();
152 if (cpu_ops[cpu]->cpu_postboot)
153 cpu_ops[cpu]->cpu_postboot();
156 * Enable GIC and timers.
158 notify_cpu_starting(cpu);
160 smp_store_cpu_info(cpu);
163 * OK, now it's safe to let the boot CPU continue. Wait for
164 * the CPU migration code to notice that the CPU is online
165 * before we continue.
167 set_cpu_online(cpu, true);
168 complete(&cpu_running);
172 local_async_enable();
175 * OK, it's off to the idle thread for us
177 cpu_startup_entry(CPUHP_ONLINE);
180 #ifdef CONFIG_HOTPLUG_CPU
181 static int op_cpu_disable(unsigned int cpu)
184 * If we don't have a cpu_die method, abort before we reach the point
185 * of no return. CPU0 may not have an cpu_ops, so test for it.
187 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
191 * We may need to abort a hot unplug for some other mechanism-specific
194 if (cpu_ops[cpu]->cpu_disable)
195 return cpu_ops[cpu]->cpu_disable(cpu);
201 * __cpu_disable runs on the processor to be shutdown.
203 int __cpu_disable(void)
205 unsigned int cpu = smp_processor_id();
208 ret = op_cpu_disable(cpu);
213 * Take this CPU offline. Once we clear this, we can't return,
214 * and we must not schedule until we're ready to give up the cpu.
216 set_cpu_online(cpu, false);
219 * OK - migrate IRQs away from this CPU
224 * Remove this CPU from the vm mask set of all processes.
226 clear_tasks_mm_cpumask(cpu);
231 static DECLARE_COMPLETION(cpu_died);
234 * called on the thread which is asking for a CPU to be shutdown -
235 * waits until shutdown has completed, or it is timed out.
237 void __cpu_die(unsigned int cpu)
239 if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
240 pr_crit("CPU%u: cpu didn't die\n", cpu);
243 pr_notice("CPU%u: shutdown\n", cpu);
247 * Called from the idle thread for the CPU which has been shutdown.
249 * Note that we disable IRQs here, but do not re-enable them
250 * before returning to the caller. This is also the behaviour
251 * of the other hotplug-cpu capable cores, so presumably coming
252 * out of idle fixes this.
256 unsigned int cpu = smp_processor_id();
262 /* Tell __cpu_die() that this CPU is now safe to dispose of */
266 * Actually shutdown the CPU. This must never fail. The specific hotplug
267 * mechanism must perform all required cache maintenance to ensure that
268 * no dirty lines are lost in the process of shutting down the CPU.
270 cpu_ops[cpu]->cpu_die(cpu);
276 void __init smp_cpus_done(unsigned int max_cpus)
278 pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
281 void __init smp_prepare_boot_cpu(void)
283 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
286 static void (*smp_cross_call)(const struct cpumask *, unsigned int);
289 * Enumerate the possible CPU set from the device tree and build the
290 * cpu logical map array containing MPIDR values related to logical
291 * cpus. Assumes that cpu_logical_map(0) has already been initialized.
293 void __init smp_init_cpus(void)
295 struct device_node *dn = NULL;
296 unsigned int i, cpu = 1;
297 bool bootcpu_valid = false;
299 while ((dn = of_find_node_by_type(dn, "cpu"))) {
304 * A cpu node with missing "reg" property is
305 * considered invalid to build a cpu_logical_map
308 cell = of_get_property(dn, "reg", NULL);
310 pr_err("%s: missing reg property\n", dn->full_name);
313 hwid = of_read_number(cell, of_n_addr_cells(dn));
316 * Non affinity bits must be set to 0 in the DT
318 if (hwid & ~MPIDR_HWID_BITMASK) {
319 pr_err("%s: invalid reg property\n", dn->full_name);
324 * Duplicate MPIDRs are a recipe for disaster. Scan
325 * all initialized entries and check for
326 * duplicates. If any is found just ignore the cpu.
327 * cpu_logical_map was initialized to INVALID_HWID to
328 * avoid matching valid MPIDR values.
330 for (i = 1; (i < cpu) && (i < NR_CPUS); i++) {
331 if (cpu_logical_map(i) == hwid) {
332 pr_err("%s: duplicate cpu reg properties in the DT\n",
339 * The numbering scheme requires that the boot CPU
340 * must be assigned logical id 0. Record it so that
341 * the logical map built from DT is validated and can
344 if (hwid == cpu_logical_map(0)) {
346 pr_err("%s: duplicate boot cpu reg property in DT\n",
351 bootcpu_valid = true;
354 * cpu_logical_map has already been
355 * initialized and the boot cpu doesn't need
356 * the enable-method so continue without
365 if (cpu_read_ops(dn, cpu) != 0)
368 if (cpu_ops[cpu]->cpu_init(dn, cpu))
371 pr_debug("cpu logical map 0x%llx\n", hwid);
372 cpu_logical_map(cpu) = hwid;
379 pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
382 if (!bootcpu_valid) {
383 pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
388 * All the cpus that made it to the cpu_logical_map have been
389 * validated so set them as possible cpus.
391 for (i = 0; i < NR_CPUS; i++)
392 if (cpu_logical_map(i) != INVALID_HWID)
393 set_cpu_possible(i, true);
396 void __init smp_prepare_cpus(unsigned int max_cpus)
399 unsigned int cpu, ncores = num_possible_cpus();
403 smp_store_cpu_info(smp_processor_id());
406 * are we trying to boot more cores than exist?
408 if (max_cpus > ncores)
411 /* Don't bother if we're effectively UP */
416 * Initialise the present map (which describes the set of CPUs
417 * actually populated at the present time) and release the
418 * secondaries from the bootloader.
420 * Make sure we online at most (max_cpus - 1) additional CPUs.
423 for_each_possible_cpu(cpu) {
427 if (cpu == smp_processor_id())
433 err = cpu_ops[cpu]->cpu_prepare(cpu);
437 set_cpu_present(cpu, true);
443 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
448 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
450 smp_cross_call(mask, IPI_CALL_FUNC);
453 void arch_send_call_function_single_ipi(int cpu)
455 smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
458 static const char *ipi_types[NR_IPI] = {
459 #define S(x,s) [x - IPI_RESCHEDULE] = s
460 S(IPI_RESCHEDULE, "Rescheduling interrupts"),
461 S(IPI_CALL_FUNC, "Function call interrupts"),
462 S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
463 S(IPI_CPU_STOP, "CPU stop interrupts"),
464 S(IPI_TIMER, "Timer broadcast interrupts"),
467 void show_ipi_list(struct seq_file *p, int prec)
471 for (i = 0; i < NR_IPI; i++) {
472 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i + IPI_RESCHEDULE,
473 prec >= 4 ? " " : "");
474 for_each_online_cpu(cpu)
475 seq_printf(p, "%10u ",
476 __get_irq_stat(cpu, ipi_irqs[i]));
477 seq_printf(p, " %s\n", ipi_types[i]);
481 u64 smp_irq_stat_cpu(unsigned int cpu)
486 for (i = 0; i < NR_IPI; i++)
487 sum += __get_irq_stat(cpu, ipi_irqs[i]);
492 static DEFINE_RAW_SPINLOCK(stop_lock);
495 * ipi_cpu_stop - handle IPI from smp_send_stop()
497 static void ipi_cpu_stop(unsigned int cpu)
499 if (system_state == SYSTEM_BOOTING ||
500 system_state == SYSTEM_RUNNING) {
501 raw_spin_lock(&stop_lock);
502 pr_crit("CPU%u: stopping\n", cpu);
504 raw_spin_unlock(&stop_lock);
507 set_cpu_online(cpu, false);
516 * Main handler for inter-processor interrupts
518 void handle_IPI(int ipinr, struct pt_regs *regs)
520 unsigned int cpu = smp_processor_id();
521 struct pt_regs *old_regs = set_irq_regs(regs);
523 if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
524 __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
533 generic_smp_call_function_interrupt();
537 case IPI_CALL_FUNC_SINGLE:
539 generic_smp_call_function_single_interrupt();
549 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
552 tick_receive_broadcast();
558 pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
561 set_irq_regs(old_regs);
564 void smp_send_reschedule(int cpu)
566 smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
569 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
570 void tick_broadcast(const struct cpumask *mask)
572 smp_cross_call(mask, IPI_TIMER);
576 void smp_send_stop(void)
578 unsigned long timeout;
580 if (num_online_cpus() > 1) {
583 cpumask_copy(&mask, cpu_online_mask);
584 cpu_clear(smp_processor_id(), mask);
586 smp_cross_call(&mask, IPI_CPU_STOP);
589 /* Wait up to one second for other CPUs to stop */
590 timeout = USEC_PER_SEC;
591 while (num_online_cpus() > 1 && timeout--)
594 if (num_online_cpus() > 1)
595 pr_warning("SMP: failed to stop secondary CPUs\n");
601 int setup_profiling_timer(unsigned int multiplier)