smp.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * SMP initialisation and IPI support
  4 * Based on arch/arm64/kernel/smp.c
  5 *
  6 * Copyright (C) 2012 ARM Ltd.
  7 * Copyright (C) 2015 Regents of the University of California
  8 * Copyright (C) 2017 SiFive
  9 */
 10
 11#include <linux/cpu.h>
 12#include <linux/clockchips.h>
 13#include <linux/interrupt.h>
 14#include <linux/module.h>
 15#include <linux/kexec.h>
 16#include <linux/kgdb.h>
 17#include <linux/percpu.h>
 18#include <linux/profile.h>
 19#include <linux/smp.h>
 20#include <linux/sched.h>
 21#include <linux/seq_file.h>
 22#include <linux/delay.h>
 23#include <linux/irq.h>
 24#include <linux/irq_work.h>
 25#include <linux/nmi.h>
 26
 27#include <asm/tlbflush.h>
 28#include <asm/cacheflush.h>
 29#include <asm/cpu_ops.h>
 30
 31enum ipi_message_type {
 32	IPI_RESCHEDULE,
 33	IPI_CALL_FUNC,
 34	IPI_CPU_STOP,
 35	IPI_CPU_CRASH_STOP,
 36	IPI_IRQ_WORK,
 37	IPI_TIMER,
 38	IPI_CPU_BACKTRACE,
 39	IPI_KGDB_ROUNDUP,
 40	IPI_MAX
 41};
 42
 43static const char * const ipi_names[] = {
 44	[IPI_RESCHEDULE]	= "Rescheduling interrupts",
 45	[IPI_CALL_FUNC]		= "Function call interrupts",
 46	[IPI_CPU_STOP]		= "CPU stop interrupts",
 47	[IPI_CPU_CRASH_STOP]	= "CPU stop (for crash dump) interrupts",
 48	[IPI_IRQ_WORK]		= "IRQ work interrupts",
 49	[IPI_TIMER]		= "Timer broadcast interrupts",
 50	[IPI_CPU_BACKTRACE]     = "CPU backtrace interrupts",
 51	[IPI_KGDB_ROUNDUP]	= "KGDB roundup interrupts",
 52};
 53
 54unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = {
 55	[0 ... NR_CPUS-1] = INVALID_HARTID
 56};
 57EXPORT_SYMBOL_GPL(__cpuid_to_hartid_map);
 58
 59void __init smp_setup_processor_id(void)
 60{
 61	cpuid_to_hartid_map(0) = boot_cpu_hartid;
 62
 63	pr_info("Booting Linux on hartid %lu\n", boot_cpu_hartid);
 64}
 65
 66static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
 67static int ipi_virq_base __ro_after_init;
 68static int nr_ipi __ro_after_init = IPI_MAX;
 69static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
 70
 71int riscv_hartid_to_cpuid(unsigned long hartid)
 72{
 73	int i;
 74
 75	for (i = 0; i < NR_CPUS; i++)
 76		if (cpuid_to_hartid_map(i) == hartid)
 77			return i;
 78
 79	return -ENOENT;
 80}
 81
 82static void ipi_stop(void)
 83{
 84	set_cpu_online(smp_processor_id(), false);
 85	while (1)
 86		wait_for_interrupt();
 87}
 88
 89#ifdef CONFIG_KEXEC_CORE
 90static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
 91
 92static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
 93{
 94	crash_save_cpu(regs, cpu);
 95
 96	atomic_dec(&waiting_for_crash_ipi);
 97
 98	local_irq_disable();
 99
100#ifdef CONFIG_HOTPLUG_CPU
101	if (cpu_has_hotplug(cpu))
102		cpu_ops->cpu_stop();
103#endif
104
105	for(;;)
106		wait_for_interrupt();
107}
108#else
109static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
110{
111	unreachable();
112}
113#endif
114
115static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
116{
117	__ipi_send_mask(ipi_desc[op], mask);
118}
119
120static void send_ipi_single(int cpu, enum ipi_message_type op)
121{
122	__ipi_send_mask(ipi_desc[op], cpumask_of(cpu));
123}
124
125#ifdef CONFIG_IRQ_WORK
126void arch_irq_work_raise(void)
127{
128	send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
129}
130#endif
131
132static irqreturn_t handle_IPI(int irq, void *data)
133{
134	unsigned int cpu = smp_processor_id();
135	int ipi = irq - ipi_virq_base;
136
137	switch (ipi) {
138	case IPI_RESCHEDULE:
139		scheduler_ipi();
140		break;
141	case IPI_CALL_FUNC:
142		generic_smp_call_function_interrupt();
143		break;
144	case IPI_CPU_STOP:
145		ipi_stop();
146		break;
147	case IPI_CPU_CRASH_STOP:
148		ipi_cpu_crash_stop(cpu, get_irq_regs());
149		break;
150	case IPI_IRQ_WORK:
151		irq_work_run();
152		break;
153#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
154	case IPI_TIMER:
155		tick_receive_broadcast();
156		break;
157#endif
158	case IPI_CPU_BACKTRACE:
159		nmi_cpu_backtrace(get_irq_regs());
160		break;
161	case IPI_KGDB_ROUNDUP:
162		kgdb_nmicallback(cpu, get_irq_regs());
163		break;
164	default:
165		pr_warn("CPU%d: unhandled IPI%d\n", cpu, ipi);
166		break;
167	}
168
169	return IRQ_HANDLED;
170}
171
172void riscv_ipi_enable(void)
173{
174	int i;
175
176	if (WARN_ON_ONCE(!ipi_virq_base))
177		return;
178
179	for (i = 0; i < nr_ipi; i++)
180		enable_percpu_irq(ipi_virq_base + i, 0);
181}
182
183void riscv_ipi_disable(void)
184{
185	int i;
186
187	if (WARN_ON_ONCE(!ipi_virq_base))
188		return;
189
190	for (i = 0; i < nr_ipi; i++)
191		disable_percpu_irq(ipi_virq_base + i);
192}
193
194bool riscv_ipi_have_virq_range(void)
195{
196	return (ipi_virq_base) ? true : false;
197}
198
199void riscv_ipi_set_virq_range(int virq, int nr)
200{
201	int i, err;
202
203	if (WARN_ON(ipi_virq_base))
204		return;
205
206	WARN_ON(nr < IPI_MAX);
207	nr_ipi = min(nr, IPI_MAX);
208	ipi_virq_base = virq;
209
210	/* Request IPIs */
211	for (i = 0; i < nr_ipi; i++) {
212		err = request_percpu_irq(ipi_virq_base + i, handle_IPI,
213					 ipi_names[i], &ipi_dummy_dev);
214		WARN_ON(err);
215
216		ipi_desc[i] = irq_to_desc(ipi_virq_base + i);
217		irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN);
218	}
219
220	/* Enabled IPIs for boot CPU immediately */
221	riscv_ipi_enable();
222}
223
224void show_ipi_stats(struct seq_file *p, int prec)
225{
226	unsigned int cpu, i;
227
228	for (i = 0; i < IPI_MAX; i++) {
229		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
230			   prec >= 4 ? " " : "");
231		for_each_online_cpu(cpu)
232			seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
233		seq_printf(p, " %s\n", ipi_names[i]);
234	}
235}
236
237void arch_send_call_function_ipi_mask(struct cpumask *mask)
238{
239	send_ipi_mask(mask, IPI_CALL_FUNC);
240}
241
242void arch_send_call_function_single_ipi(int cpu)
243{
244	send_ipi_single(cpu, IPI_CALL_FUNC);
245}
246
247#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
248void tick_broadcast(const struct cpumask *mask)
249{
250	send_ipi_mask(mask, IPI_TIMER);
251}
252#endif
253
254void smp_send_stop(void)
255{
256	unsigned long timeout;
257
258	if (num_online_cpus() > 1) {
259		cpumask_t mask;
260
261		cpumask_copy(&mask, cpu_online_mask);
262		cpumask_clear_cpu(smp_processor_id(), &mask);
263
264		if (system_state <= SYSTEM_RUNNING)
265			pr_crit("SMP: stopping secondary CPUs\n");
266		send_ipi_mask(&mask, IPI_CPU_STOP);
267	}
268
269	/* Wait up to one second for other CPUs to stop */
270	timeout = USEC_PER_SEC;
271	while (num_online_cpus() > 1 && timeout--)
272		udelay(1);
273
274	if (num_online_cpus() > 1)
275		pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
276			   cpumask_pr_args(cpu_online_mask));
277}
278
279#ifdef CONFIG_KEXEC_CORE
280/*
281 * The number of CPUs online, not counting this CPU (which may not be
282 * fully online and so not counted in num_online_cpus()).
283 */
284static inline unsigned int num_other_online_cpus(void)
285{
286	unsigned int this_cpu_online = cpu_online(smp_processor_id());
287
288	return num_online_cpus() - this_cpu_online;
289}
290
291void crash_smp_send_stop(void)
292{
293	static int cpus_stopped;
294	cpumask_t mask;
295	unsigned long timeout;
296
297	/*
298	 * This function can be called twice in panic path, but obviously
299	 * we execute this only once.
300	 */
301	if (cpus_stopped)
302		return;
303
304	cpus_stopped = 1;
305
306	/*
307	 * If this cpu is the only one alive at this point in time, online or
308	 * not, there are no stop messages to be sent around, so just back out.
309	 */
310	if (num_other_online_cpus() == 0)
311		return;
312
313	cpumask_copy(&mask, cpu_online_mask);
314	cpumask_clear_cpu(smp_processor_id(), &mask);
315
316	atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
317
318	pr_crit("SMP: stopping secondary CPUs\n");
319	send_ipi_mask(&mask, IPI_CPU_CRASH_STOP);
320
321	/* Wait up to one second for other CPUs to stop */
322	timeout = USEC_PER_SEC;
323	while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
324		udelay(1);
325
326	if (atomic_read(&waiting_for_crash_ipi) > 0)
327		pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
328			cpumask_pr_args(&mask));
329}
330
331bool smp_crash_stop_failed(void)
332{
333	return (atomic_read(&waiting_for_crash_ipi) > 0);
334}
335#endif
336
337void arch_smp_send_reschedule(int cpu)
338{
339	send_ipi_single(cpu, IPI_RESCHEDULE);
340}
341EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
342
343static void riscv_backtrace_ipi(cpumask_t *mask)
344{
345	send_ipi_mask(mask, IPI_CPU_BACKTRACE);
346}
347
348void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
349{
350	nmi_trigger_cpumask_backtrace(mask, exclude_cpu, riscv_backtrace_ipi);
351}
352
353#ifdef CONFIG_KGDB
354void kgdb_roundup_cpus(void)
355{
356	int this_cpu = raw_smp_processor_id();
357	int cpu;
358
359	for_each_online_cpu(cpu) {
360		/* No need to roundup ourselves */
361		if (cpu == this_cpu)
362			continue;
363
364		send_ipi_single(cpu, IPI_KGDB_ROUNDUP);
365	}
366}
367#endif