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;
67 * Boot a secondary CPU, and assign it the specified idle task.
68 * This also gives us the initial stack to use for this CPU.
70 static int boot_secondary(unsigned int cpu, struct task_struct *idle)
72 if (cpu_ops[cpu]->cpu_boot)
73 return cpu_ops[cpu]->cpu_boot(cpu);
78 static DECLARE_COMPLETION(cpu_running);
80 int __cpu_up(unsigned int cpu, struct task_struct *idle)
85 * We need to tell the secondary core where to find its stack and the
88 secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
89 __flush_dcache_area(&secondary_data, sizeof(secondary_data));
92 * Now bring the CPU into our world.
94 ret = boot_secondary(cpu, idle);
97 * CPU was successfully started, wait for it to come online or
100 wait_for_completion_timeout(&cpu_running,
101 msecs_to_jiffies(1000));
103 if (!cpu_online(cpu)) {
104 pr_crit("CPU%u: failed to come online\n", cpu);
108 pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
111 secondary_data.stack = NULL;
117 * This is the secondary CPU boot entry. We're using this CPUs
118 * idle thread stack, but a set of temporary page tables.
120 asmlinkage void secondary_start_kernel(void)
122 struct mm_struct *mm = &init_mm;
123 unsigned int cpu = smp_processor_id();
125 printk("CPU%u: Booted secondary processor\n", cpu);
128 * All kernel threads share the same mm context; grab a
129 * reference and switch to it.
131 atomic_inc(&mm->mm_count);
132 current->active_mm = mm;
133 cpumask_set_cpu(cpu, mm_cpumask(mm));
136 * TTBR0 is only used for the identity mapping at this stage. Make it
137 * point to zero page to avoid speculatively fetching new entries.
139 cpu_set_reserved_ttbr0();
143 trace_hardirqs_off();
145 if (cpu_ops[cpu]->cpu_postboot)
146 cpu_ops[cpu]->cpu_postboot();
149 * Enable GIC and timers.
151 notify_cpu_starting(cpu);
154 * OK, now it's safe to let the boot CPU continue. Wait for
155 * the CPU migration code to notice that the CPU is online
156 * before we continue.
158 set_cpu_online(cpu, true);
159 complete(&cpu_running);
165 * OK, it's off to the idle thread for us
167 cpu_startup_entry(CPUHP_ONLINE);
170 #ifdef CONFIG_HOTPLUG_CPU
171 static int op_cpu_disable(unsigned int cpu)
174 * If we don't have a cpu_die method, abort before we reach the point
175 * of no return. CPU0 may not have an cpu_ops, so test for it.
177 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
181 * We may need to abort a hot unplug for some other mechanism-specific
184 if (cpu_ops[cpu]->cpu_disable)
185 return cpu_ops[cpu]->cpu_disable(cpu);
191 * __cpu_disable runs on the processor to be shutdown.
193 int __cpu_disable(void)
195 unsigned int cpu = smp_processor_id();
198 ret = op_cpu_disable(cpu);
203 * Take this CPU offline. Once we clear this, we can't return,
204 * and we must not schedule until we're ready to give up the cpu.
206 set_cpu_online(cpu, false);
209 * OK - migrate IRQs away from this CPU
214 * Remove this CPU from the vm mask set of all processes.
216 clear_tasks_mm_cpumask(cpu);
221 static DECLARE_COMPLETION(cpu_died);
224 * called on the thread which is asking for a CPU to be shutdown -
225 * waits until shutdown has completed, or it is timed out.
227 void __cpu_die(unsigned int cpu)
229 if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
230 pr_crit("CPU%u: cpu didn't die\n", cpu);
233 pr_notice("CPU%u: shutdown\n", cpu);
237 * Called from the idle thread for the CPU which has been shutdown.
239 * Note that we disable IRQs here, but do not re-enable them
240 * before returning to the caller. This is also the behaviour
241 * of the other hotplug-cpu capable cores, so presumably coming
242 * out of idle fixes this.
246 unsigned int cpu = smp_processor_id();
252 /* Tell __cpu_die() that this CPU is now safe to dispose of */
256 * Actually shutdown the CPU. This must never fail. The specific hotplug
257 * mechanism must perform all required cache maintenance to ensure that
258 * no dirty lines are lost in the process of shutting down the CPU.
260 cpu_ops[cpu]->cpu_die(cpu);
266 void __init smp_cpus_done(unsigned int max_cpus)
268 pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
271 void __init smp_prepare_boot_cpu(void)
275 static void (*smp_cross_call)(const struct cpumask *, unsigned int);
278 * Enumerate the possible CPU set from the device tree and build the
279 * cpu logical map array containing MPIDR values related to logical
280 * cpus. Assumes that cpu_logical_map(0) has already been initialized.
282 void __init smp_init_cpus(void)
284 struct device_node *dn = NULL;
285 unsigned int i, cpu = 1;
286 bool bootcpu_valid = false;
288 while ((dn = of_find_node_by_type(dn, "cpu"))) {
293 * A cpu node with missing "reg" property is
294 * considered invalid to build a cpu_logical_map
297 cell = of_get_property(dn, "reg", NULL);
299 pr_err("%s: missing reg property\n", dn->full_name);
302 hwid = of_read_number(cell, of_n_addr_cells(dn));
305 * Non affinity bits must be set to 0 in the DT
307 if (hwid & ~MPIDR_HWID_BITMASK) {
308 pr_err("%s: invalid reg property\n", dn->full_name);
313 * Duplicate MPIDRs are a recipe for disaster. Scan
314 * all initialized entries and check for
315 * duplicates. If any is found just ignore the cpu.
316 * cpu_logical_map was initialized to INVALID_HWID to
317 * avoid matching valid MPIDR values.
319 for (i = 1; (i < cpu) && (i < NR_CPUS); i++) {
320 if (cpu_logical_map(i) == hwid) {
321 pr_err("%s: duplicate cpu reg properties in the DT\n",
328 * The numbering scheme requires that the boot CPU
329 * must be assigned logical id 0. Record it so that
330 * the logical map built from DT is validated and can
333 if (hwid == cpu_logical_map(0)) {
335 pr_err("%s: duplicate boot cpu reg property in DT\n",
340 bootcpu_valid = true;
343 * cpu_logical_map has already been
344 * initialized and the boot cpu doesn't need
345 * the enable-method so continue without
354 if (cpu_read_ops(dn, cpu) != 0)
357 if (cpu_ops[cpu]->cpu_init(dn, cpu))
360 pr_debug("cpu logical map 0x%llx\n", hwid);
361 cpu_logical_map(cpu) = hwid;
368 pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
371 if (!bootcpu_valid) {
372 pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
377 * All the cpus that made it to the cpu_logical_map have been
378 * validated so set them as possible cpus.
380 for (i = 0; i < NR_CPUS; i++)
381 if (cpu_logical_map(i) != INVALID_HWID)
382 set_cpu_possible(i, true);
385 void __init smp_prepare_cpus(unsigned int max_cpus)
388 unsigned int cpu, ncores = num_possible_cpus();
391 * are we trying to boot more cores than exist?
393 if (max_cpus > ncores)
396 /* Don't bother if we're effectively UP */
401 * Initialise the present map (which describes the set of CPUs
402 * actually populated at the present time) and release the
403 * secondaries from the bootloader.
405 * Make sure we online at most (max_cpus - 1) additional CPUs.
408 for_each_possible_cpu(cpu) {
412 if (cpu == smp_processor_id())
418 err = cpu_ops[cpu]->cpu_prepare(cpu);
422 set_cpu_present(cpu, true);
428 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
433 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
435 smp_cross_call(mask, IPI_CALL_FUNC);
438 void arch_send_call_function_single_ipi(int cpu)
440 smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
443 static const char *ipi_types[NR_IPI] = {
444 #define S(x,s) [x - IPI_RESCHEDULE] = s
445 S(IPI_RESCHEDULE, "Rescheduling interrupts"),
446 S(IPI_CALL_FUNC, "Function call interrupts"),
447 S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
448 S(IPI_CPU_STOP, "CPU stop interrupts"),
451 void show_ipi_list(struct seq_file *p, int prec)
455 for (i = 0; i < NR_IPI; i++) {
456 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i + IPI_RESCHEDULE,
457 prec >= 4 ? " " : "");
458 for_each_online_cpu(cpu)
459 seq_printf(p, "%10u ",
460 __get_irq_stat(cpu, ipi_irqs[i]));
461 seq_printf(p, " %s\n", ipi_types[i]);
465 u64 smp_irq_stat_cpu(unsigned int cpu)
470 for (i = 0; i < NR_IPI; i++)
471 sum += __get_irq_stat(cpu, ipi_irqs[i]);
476 static DEFINE_RAW_SPINLOCK(stop_lock);
479 * ipi_cpu_stop - handle IPI from smp_send_stop()
481 static void ipi_cpu_stop(unsigned int cpu)
483 if (system_state == SYSTEM_BOOTING ||
484 system_state == SYSTEM_RUNNING) {
485 raw_spin_lock(&stop_lock);
486 pr_crit("CPU%u: stopping\n", cpu);
488 raw_spin_unlock(&stop_lock);
491 set_cpu_online(cpu, false);
501 * Main handler for inter-processor interrupts
503 void handle_IPI(int ipinr, struct pt_regs *regs)
505 unsigned int cpu = smp_processor_id();
506 struct pt_regs *old_regs = set_irq_regs(regs);
508 if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
509 __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
518 generic_smp_call_function_interrupt();
522 case IPI_CALL_FUNC_SINGLE:
524 generic_smp_call_function_single_interrupt();
535 pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
538 set_irq_regs(old_regs);
541 void smp_send_reschedule(int cpu)
543 smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
546 void smp_send_stop(void)
548 unsigned long timeout;
550 if (num_online_cpus() > 1) {
553 cpumask_copy(&mask, cpu_online_mask);
554 cpu_clear(smp_processor_id(), mask);
556 smp_cross_call(&mask, IPI_CPU_STOP);
559 /* Wait up to one second for other CPUs to stop */
560 timeout = USEC_PER_SEC;
561 while (num_online_cpus() > 1 && timeout--)
564 if (num_online_cpus() > 1)
565 pr_warning("SMP: failed to stop secondary CPUs\n");
571 int setup_profiling_timer(unsigned int multiplier)