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;
118 * This is the secondary CPU boot entry. We're using this CPUs
119 * idle thread stack, but a set of temporary page tables.
121 asmlinkage void secondary_start_kernel(void)
123 struct mm_struct *mm = &init_mm;
124 unsigned int cpu = smp_processor_id();
127 * All kernel threads share the same mm context; grab a
128 * reference and switch to it.
130 atomic_inc(&mm->mm_count);
131 current->active_mm = mm;
132 cpumask_set_cpu(cpu, mm_cpumask(mm));
134 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
135 printk("CPU%u: Booted secondary processor\n", cpu);
138 * TTBR0 is only used for the identity mapping at this stage. Make it
139 * point to zero page to avoid speculatively fetching new entries.
141 cpu_set_reserved_ttbr0();
145 trace_hardirqs_off();
147 if (cpu_ops[cpu]->cpu_postboot)
148 cpu_ops[cpu]->cpu_postboot();
151 * Enable GIC and timers.
153 notify_cpu_starting(cpu);
156 * OK, now it's safe to let the boot CPU continue. Wait for
157 * the CPU migration code to notice that the CPU is online
158 * before we continue.
160 set_cpu_online(cpu, true);
161 complete(&cpu_running);
165 local_async_enable();
168 * OK, it's off to the idle thread for us
170 cpu_startup_entry(CPUHP_ONLINE);
173 #ifdef CONFIG_HOTPLUG_CPU
174 static int op_cpu_disable(unsigned int cpu)
177 * If we don't have a cpu_die method, abort before we reach the point
178 * of no return. CPU0 may not have an cpu_ops, so test for it.
180 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
184 * We may need to abort a hot unplug for some other mechanism-specific
187 if (cpu_ops[cpu]->cpu_disable)
188 return cpu_ops[cpu]->cpu_disable(cpu);
194 * __cpu_disable runs on the processor to be shutdown.
196 int __cpu_disable(void)
198 unsigned int cpu = smp_processor_id();
201 ret = op_cpu_disable(cpu);
206 * Take this CPU offline. Once we clear this, we can't return,
207 * and we must not schedule until we're ready to give up the cpu.
209 set_cpu_online(cpu, false);
212 * OK - migrate IRQs away from this CPU
217 * Remove this CPU from the vm mask set of all processes.
219 clear_tasks_mm_cpumask(cpu);
224 static DECLARE_COMPLETION(cpu_died);
227 * called on the thread which is asking for a CPU to be shutdown -
228 * waits until shutdown has completed, or it is timed out.
230 void __cpu_die(unsigned int cpu)
232 if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
233 pr_crit("CPU%u: cpu didn't die\n", cpu);
236 pr_notice("CPU%u: shutdown\n", cpu);
240 * Called from the idle thread for the CPU which has been shutdown.
242 * Note that we disable IRQs here, but do not re-enable them
243 * before returning to the caller. This is also the behaviour
244 * of the other hotplug-cpu capable cores, so presumably coming
245 * out of idle fixes this.
249 unsigned int cpu = smp_processor_id();
255 /* Tell __cpu_die() that this CPU is now safe to dispose of */
259 * Actually shutdown the CPU. This must never fail. The specific hotplug
260 * mechanism must perform all required cache maintenance to ensure that
261 * no dirty lines are lost in the process of shutting down the CPU.
263 cpu_ops[cpu]->cpu_die(cpu);
269 void __init smp_cpus_done(unsigned int max_cpus)
271 pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
274 void __init smp_prepare_boot_cpu(void)
276 set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
279 static void (*smp_cross_call)(const struct cpumask *, unsigned int);
282 * Enumerate the possible CPU set from the device tree and build the
283 * cpu logical map array containing MPIDR values related to logical
284 * cpus. Assumes that cpu_logical_map(0) has already been initialized.
286 void __init smp_init_cpus(void)
288 struct device_node *dn = NULL;
289 unsigned int i, cpu = 1;
290 bool bootcpu_valid = false;
292 while ((dn = of_find_node_by_type(dn, "cpu"))) {
297 * A cpu node with missing "reg" property is
298 * considered invalid to build a cpu_logical_map
301 cell = of_get_property(dn, "reg", NULL);
303 pr_err("%s: missing reg property\n", dn->full_name);
306 hwid = of_read_number(cell, of_n_addr_cells(dn));
309 * Non affinity bits must be set to 0 in the DT
311 if (hwid & ~MPIDR_HWID_BITMASK) {
312 pr_err("%s: invalid reg property\n", dn->full_name);
317 * Duplicate MPIDRs are a recipe for disaster. Scan
318 * all initialized entries and check for
319 * duplicates. If any is found just ignore the cpu.
320 * cpu_logical_map was initialized to INVALID_HWID to
321 * avoid matching valid MPIDR values.
323 for (i = 1; (i < cpu) && (i < NR_CPUS); i++) {
324 if (cpu_logical_map(i) == hwid) {
325 pr_err("%s: duplicate cpu reg properties in the DT\n",
332 * The numbering scheme requires that the boot CPU
333 * must be assigned logical id 0. Record it so that
334 * the logical map built from DT is validated and can
337 if (hwid == cpu_logical_map(0)) {
339 pr_err("%s: duplicate boot cpu reg property in DT\n",
344 bootcpu_valid = true;
347 * cpu_logical_map has already been
348 * initialized and the boot cpu doesn't need
349 * the enable-method so continue without
358 if (cpu_read_ops(dn, cpu) != 0)
361 if (cpu_ops[cpu]->cpu_init(dn, cpu))
364 pr_debug("cpu logical map 0x%llx\n", hwid);
365 cpu_logical_map(cpu) = hwid;
372 pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
375 if (!bootcpu_valid) {
376 pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
381 * All the cpus that made it to the cpu_logical_map have been
382 * validated so set them as possible cpus.
384 for (i = 0; i < NR_CPUS; i++)
385 if (cpu_logical_map(i) != INVALID_HWID)
386 set_cpu_possible(i, true);
389 void __init smp_prepare_cpus(unsigned int max_cpus)
392 unsigned int cpu, ncores = num_possible_cpus();
395 * are we trying to boot more cores than exist?
397 if (max_cpus > ncores)
400 /* Don't bother if we're effectively UP */
405 * Initialise the present map (which describes the set of CPUs
406 * actually populated at the present time) and release the
407 * secondaries from the bootloader.
409 * Make sure we online at most (max_cpus - 1) additional CPUs.
412 for_each_possible_cpu(cpu) {
416 if (cpu == smp_processor_id())
422 err = cpu_ops[cpu]->cpu_prepare(cpu);
426 set_cpu_present(cpu, true);
432 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
437 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
439 smp_cross_call(mask, IPI_CALL_FUNC);
442 void arch_send_call_function_single_ipi(int cpu)
444 smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
447 static const char *ipi_types[NR_IPI] = {
448 #define S(x,s) [x - IPI_RESCHEDULE] = s
449 S(IPI_RESCHEDULE, "Rescheduling interrupts"),
450 S(IPI_CALL_FUNC, "Function call interrupts"),
451 S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
452 S(IPI_CPU_STOP, "CPU stop interrupts"),
453 S(IPI_TIMER, "Timer broadcast interrupts"),
456 void show_ipi_list(struct seq_file *p, int prec)
460 for (i = 0; i < NR_IPI; i++) {
461 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i + IPI_RESCHEDULE,
462 prec >= 4 ? " " : "");
463 for_each_online_cpu(cpu)
464 seq_printf(p, "%10u ",
465 __get_irq_stat(cpu, ipi_irqs[i]));
466 seq_printf(p, " %s\n", ipi_types[i]);
470 u64 smp_irq_stat_cpu(unsigned int cpu)
475 for (i = 0; i < NR_IPI; i++)
476 sum += __get_irq_stat(cpu, ipi_irqs[i]);
481 static DEFINE_RAW_SPINLOCK(stop_lock);
484 * ipi_cpu_stop - handle IPI from smp_send_stop()
486 static void ipi_cpu_stop(unsigned int cpu)
488 if (system_state == SYSTEM_BOOTING ||
489 system_state == SYSTEM_RUNNING) {
490 raw_spin_lock(&stop_lock);
491 pr_crit("CPU%u: stopping\n", cpu);
493 raw_spin_unlock(&stop_lock);
496 set_cpu_online(cpu, false);
506 * Main handler for inter-processor interrupts
508 void handle_IPI(int ipinr, struct pt_regs *regs)
510 unsigned int cpu = smp_processor_id();
511 struct pt_regs *old_regs = set_irq_regs(regs);
513 if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
514 __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
523 generic_smp_call_function_interrupt();
527 case IPI_CALL_FUNC_SINGLE:
529 generic_smp_call_function_single_interrupt();
539 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
542 tick_receive_broadcast();
548 pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
551 set_irq_regs(old_regs);
554 void smp_send_reschedule(int cpu)
556 smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
559 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
560 void tick_broadcast(const struct cpumask *mask)
562 smp_cross_call(mask, IPI_TIMER);
566 void smp_send_stop(void)
568 unsigned long timeout;
570 if (num_online_cpus() > 1) {
573 cpumask_copy(&mask, cpu_online_mask);
574 cpu_clear(smp_processor_id(), mask);
576 smp_cross_call(&mask, IPI_CPU_STOP);
579 /* Wait up to one second for other CPUs to stop */
580 timeout = USEC_PER_SEC;
581 while (num_online_cpus() > 1 && timeout--)
584 if (num_online_cpus() > 1)
585 pr_warning("SMP: failed to stop secondary CPUs\n");
591 int setup_profiling_timer(unsigned int multiplier)