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);
163 local_async_enable();
166 * OK, it's off to the idle thread for us
168 cpu_startup_entry(CPUHP_ONLINE);
171 #ifdef CONFIG_HOTPLUG_CPU
172 static int op_cpu_disable(unsigned int cpu)
175 * If we don't have a cpu_die method, abort before we reach the point
176 * of no return. CPU0 may not have an cpu_ops, so test for it.
178 if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_die)
182 * We may need to abort a hot unplug for some other mechanism-specific
185 if (cpu_ops[cpu]->cpu_disable)
186 return cpu_ops[cpu]->cpu_disable(cpu);
192 * __cpu_disable runs on the processor to be shutdown.
194 int __cpu_disable(void)
196 unsigned int cpu = smp_processor_id();
199 ret = op_cpu_disable(cpu);
204 * Take this CPU offline. Once we clear this, we can't return,
205 * and we must not schedule until we're ready to give up the cpu.
207 set_cpu_online(cpu, false);
210 * OK - migrate IRQs away from this CPU
215 * Remove this CPU from the vm mask set of all processes.
217 clear_tasks_mm_cpumask(cpu);
222 static DECLARE_COMPLETION(cpu_died);
225 * called on the thread which is asking for a CPU to be shutdown -
226 * waits until shutdown has completed, or it is timed out.
228 void __cpu_die(unsigned int cpu)
230 if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
231 pr_crit("CPU%u: cpu didn't die\n", cpu);
234 pr_notice("CPU%u: shutdown\n", cpu);
238 * Called from the idle thread for the CPU which has been shutdown.
240 * Note that we disable IRQs here, but do not re-enable them
241 * before returning to the caller. This is also the behaviour
242 * of the other hotplug-cpu capable cores, so presumably coming
243 * out of idle fixes this.
247 unsigned int cpu = smp_processor_id();
253 /* Tell __cpu_die() that this CPU is now safe to dispose of */
257 * Actually shutdown the CPU. This must never fail. The specific hotplug
258 * mechanism must perform all required cache maintenance to ensure that
259 * no dirty lines are lost in the process of shutting down the CPU.
261 cpu_ops[cpu]->cpu_die(cpu);
267 void __init smp_cpus_done(unsigned int max_cpus)
269 pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
272 void __init smp_prepare_boot_cpu(void)
276 static void (*smp_cross_call)(const struct cpumask *, unsigned int);
279 * Enumerate the possible CPU set from the device tree and build the
280 * cpu logical map array containing MPIDR values related to logical
281 * cpus. Assumes that cpu_logical_map(0) has already been initialized.
283 void __init smp_init_cpus(void)
285 struct device_node *dn = NULL;
286 unsigned int i, cpu = 1;
287 bool bootcpu_valid = false;
289 while ((dn = of_find_node_by_type(dn, "cpu"))) {
294 * A cpu node with missing "reg" property is
295 * considered invalid to build a cpu_logical_map
298 cell = of_get_property(dn, "reg", NULL);
300 pr_err("%s: missing reg property\n", dn->full_name);
303 hwid = of_read_number(cell, of_n_addr_cells(dn));
306 * Non affinity bits must be set to 0 in the DT
308 if (hwid & ~MPIDR_HWID_BITMASK) {
309 pr_err("%s: invalid reg property\n", dn->full_name);
314 * Duplicate MPIDRs are a recipe for disaster. Scan
315 * all initialized entries and check for
316 * duplicates. If any is found just ignore the cpu.
317 * cpu_logical_map was initialized to INVALID_HWID to
318 * avoid matching valid MPIDR values.
320 for (i = 1; (i < cpu) && (i < NR_CPUS); i++) {
321 if (cpu_logical_map(i) == hwid) {
322 pr_err("%s: duplicate cpu reg properties in the DT\n",
329 * The numbering scheme requires that the boot CPU
330 * must be assigned logical id 0. Record it so that
331 * the logical map built from DT is validated and can
334 if (hwid == cpu_logical_map(0)) {
336 pr_err("%s: duplicate boot cpu reg property in DT\n",
341 bootcpu_valid = true;
344 * cpu_logical_map has already been
345 * initialized and the boot cpu doesn't need
346 * the enable-method so continue without
355 if (cpu_read_ops(dn, cpu) != 0)
358 if (cpu_ops[cpu]->cpu_init(dn, cpu))
361 pr_debug("cpu logical map 0x%llx\n", hwid);
362 cpu_logical_map(cpu) = hwid;
369 pr_warning("no. of cores (%d) greater than configured maximum of %d - clipping\n",
372 if (!bootcpu_valid) {
373 pr_err("DT missing boot CPU MPIDR, not enabling secondaries\n");
378 * All the cpus that made it to the cpu_logical_map have been
379 * validated so set them as possible cpus.
381 for (i = 0; i < NR_CPUS; i++)
382 if (cpu_logical_map(i) != INVALID_HWID)
383 set_cpu_possible(i, true);
386 void __init smp_prepare_cpus(unsigned int max_cpus)
389 unsigned int cpu, ncores = num_possible_cpus();
392 * are we trying to boot more cores than exist?
394 if (max_cpus > ncores)
397 /* Don't bother if we're effectively UP */
402 * Initialise the present map (which describes the set of CPUs
403 * actually populated at the present time) and release the
404 * secondaries from the bootloader.
406 * Make sure we online at most (max_cpus - 1) additional CPUs.
409 for_each_possible_cpu(cpu) {
413 if (cpu == smp_processor_id())
419 err = cpu_ops[cpu]->cpu_prepare(cpu);
423 set_cpu_present(cpu, true);
429 void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
434 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
436 smp_cross_call(mask, IPI_CALL_FUNC);
439 void arch_send_call_function_single_ipi(int cpu)
441 smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
444 static const char *ipi_types[NR_IPI] = {
445 #define S(x,s) [x - IPI_RESCHEDULE] = s
446 S(IPI_RESCHEDULE, "Rescheduling interrupts"),
447 S(IPI_CALL_FUNC, "Function call interrupts"),
448 S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
449 S(IPI_CPU_STOP, "CPU stop interrupts"),
452 void show_ipi_list(struct seq_file *p, int prec)
456 for (i = 0; i < NR_IPI; i++) {
457 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i + IPI_RESCHEDULE,
458 prec >= 4 ? " " : "");
459 for_each_online_cpu(cpu)
460 seq_printf(p, "%10u ",
461 __get_irq_stat(cpu, ipi_irqs[i]));
462 seq_printf(p, " %s\n", ipi_types[i]);
466 u64 smp_irq_stat_cpu(unsigned int cpu)
471 for (i = 0; i < NR_IPI; i++)
472 sum += __get_irq_stat(cpu, ipi_irqs[i]);
477 static DEFINE_RAW_SPINLOCK(stop_lock);
480 * ipi_cpu_stop - handle IPI from smp_send_stop()
482 static void ipi_cpu_stop(unsigned int cpu)
484 if (system_state == SYSTEM_BOOTING ||
485 system_state == SYSTEM_RUNNING) {
486 raw_spin_lock(&stop_lock);
487 pr_crit("CPU%u: stopping\n", cpu);
489 raw_spin_unlock(&stop_lock);
492 set_cpu_online(cpu, false);
502 * Main handler for inter-processor interrupts
504 void handle_IPI(int ipinr, struct pt_regs *regs)
506 unsigned int cpu = smp_processor_id();
507 struct pt_regs *old_regs = set_irq_regs(regs);
509 if (ipinr >= IPI_RESCHEDULE && ipinr < IPI_RESCHEDULE + NR_IPI)
510 __inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_RESCHEDULE]);
519 generic_smp_call_function_interrupt();
523 case IPI_CALL_FUNC_SINGLE:
525 generic_smp_call_function_single_interrupt();
536 pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr);
539 set_irq_regs(old_regs);
542 void smp_send_reschedule(int cpu)
544 smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
547 void smp_send_stop(void)
549 unsigned long timeout;
551 if (num_online_cpus() > 1) {
554 cpumask_copy(&mask, cpu_online_mask);
555 cpu_clear(smp_processor_id(), mask);
557 smp_cross_call(&mask, IPI_CPU_STOP);
560 /* Wait up to one second for other CPUs to stop */
561 timeout = USEC_PER_SEC;
562 while (num_online_cpus() > 1 && timeout--)
565 if (num_online_cpus() > 1)
566 pr_warning("SMP: failed to stop secondary CPUs\n");
572 int setup_profiling_timer(unsigned int multiplier)