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
31 enum 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
43 static 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
54 unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = {
55 [0 ... NR_CPUS-1] = INVALID_HARTID
56 };
57 EXPORT_SYMBOL_GPL(__cpuid_to_hartid_map);
58
smp_setup_processor_id(void)59 void __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
66 static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
67 static int ipi_virq_base __ro_after_init;
68 static int nr_ipi __ro_after_init = IPI_MAX;
69 static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
70
riscv_hartid_to_cpuid(unsigned long hartid)71 int 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
ipi_stop(void)82 static 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
90 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
91
ipi_cpu_crash_stop(unsigned int cpu,struct pt_regs * regs)92 static 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
ipi_cpu_crash_stop(unsigned int cpu,struct pt_regs * regs)109 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
110 {
111 unreachable();
112 }
113 #endif
114
send_ipi_mask(const struct cpumask * mask,enum ipi_message_type op)115 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
116 {
117 __ipi_send_mask(ipi_desc[op], mask);
118 }
119
send_ipi_single(int cpu,enum ipi_message_type op)120 static 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
arch_irq_work_raise(void)126 void arch_irq_work_raise(void)
127 {
128 send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
129 }
130 #endif
131
handle_IPI(int irq,void * data)132 static 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
riscv_ipi_enable(void)172 void 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
riscv_ipi_disable(void)183 void 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
riscv_ipi_have_virq_range(void)194 bool riscv_ipi_have_virq_range(void)
195 {
196 return (ipi_virq_base) ? true : false;
197 }
198
riscv_ipi_set_virq_range(int virq,int nr)199 void 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
show_ipi_stats(struct seq_file * p,int prec)224 void 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
arch_send_call_function_ipi_mask(struct cpumask * mask)237 void arch_send_call_function_ipi_mask(struct cpumask *mask)
238 {
239 send_ipi_mask(mask, IPI_CALL_FUNC);
240 }
241
arch_send_call_function_single_ipi(int cpu)242 void 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
tick_broadcast(const struct cpumask * mask)248 void tick_broadcast(const struct cpumask *mask)
249 {
250 send_ipi_mask(mask, IPI_TIMER);
251 }
252 #endif
253
smp_send_stop(void)254 void 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 */
num_other_online_cpus(void)284 static 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
crash_smp_send_stop(void)291 void 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
smp_crash_stop_failed(void)331 bool smp_crash_stop_failed(void)
332 {
333 return (atomic_read(&waiting_for_crash_ipi) > 0);
334 }
335 #endif
336
arch_smp_send_reschedule(int cpu)337 void arch_smp_send_reschedule(int cpu)
338 {
339 send_ipi_single(cpu, IPI_RESCHEDULE);
340 }
341 EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
342
riscv_backtrace_ipi(cpumask_t * mask)343 static void riscv_backtrace_ipi(cpumask_t *mask)
344 {
345 send_ipi_mask(mask, IPI_CPU_BACKTRACE);
346 }
347
arch_trigger_cpumask_backtrace(const cpumask_t * mask,int exclude_cpu)348 void 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
kgdb_roundup_cpus(void)354 void 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
368