GNU Linux-libre 6.7.9-gnu
[releases.git] / arch / riscv / kernel / 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/percpu.h>
17 #include <linux/profile.h>
18 #include <linux/smp.h>
19 #include <linux/sched.h>
20 #include <linux/seq_file.h>
21 #include <linux/delay.h>
22 #include <linux/irq.h>
23 #include <linux/irq_work.h>
24
25 #include <asm/tlbflush.h>
26 #include <asm/cacheflush.h>
27 #include <asm/cpu_ops.h>
28
29 enum ipi_message_type {
30         IPI_RESCHEDULE,
31         IPI_CALL_FUNC,
32         IPI_CPU_STOP,
33         IPI_CPU_CRASH_STOP,
34         IPI_IRQ_WORK,
35         IPI_TIMER,
36         IPI_MAX
37 };
38
39 unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = {
40         [0 ... NR_CPUS-1] = INVALID_HARTID
41 };
42
43 void __init smp_setup_processor_id(void)
44 {
45         cpuid_to_hartid_map(0) = boot_cpu_hartid;
46 }
47
48 static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
49 static int ipi_virq_base __ro_after_init;
50 static int nr_ipi __ro_after_init = IPI_MAX;
51 static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
52
53 int riscv_hartid_to_cpuid(unsigned long hartid)
54 {
55         int i;
56
57         for (i = 0; i < NR_CPUS; i++)
58                 if (cpuid_to_hartid_map(i) == hartid)
59                         return i;
60
61         return -ENOENT;
62 }
63
64 static void ipi_stop(void)
65 {
66         set_cpu_online(smp_processor_id(), false);
67         while (1)
68                 wait_for_interrupt();
69 }
70
71 #ifdef CONFIG_KEXEC_CORE
72 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
73
74 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
75 {
76         crash_save_cpu(regs, cpu);
77
78         atomic_dec(&waiting_for_crash_ipi);
79
80         local_irq_disable();
81
82 #ifdef CONFIG_HOTPLUG_CPU
83         if (cpu_has_hotplug(cpu))
84                 cpu_ops[cpu]->cpu_stop();
85 #endif
86
87         for(;;)
88                 wait_for_interrupt();
89 }
90 #else
91 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
92 {
93         unreachable();
94 }
95 #endif
96
97 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
98 {
99         __ipi_send_mask(ipi_desc[op], mask);
100 }
101
102 static void send_ipi_single(int cpu, enum ipi_message_type op)
103 {
104         __ipi_send_mask(ipi_desc[op], cpumask_of(cpu));
105 }
106
107 #ifdef CONFIG_IRQ_WORK
108 void arch_irq_work_raise(void)
109 {
110         send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
111 }
112 #endif
113
114 static irqreturn_t handle_IPI(int irq, void *data)
115 {
116         int ipi = irq - ipi_virq_base;
117
118         switch (ipi) {
119         case IPI_RESCHEDULE:
120                 scheduler_ipi();
121                 break;
122         case IPI_CALL_FUNC:
123                 generic_smp_call_function_interrupt();
124                 break;
125         case IPI_CPU_STOP:
126                 ipi_stop();
127                 break;
128         case IPI_CPU_CRASH_STOP:
129                 ipi_cpu_crash_stop(smp_processor_id(), get_irq_regs());
130                 break;
131         case IPI_IRQ_WORK:
132                 irq_work_run();
133                 break;
134 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
135         case IPI_TIMER:
136                 tick_receive_broadcast();
137                 break;
138 #endif
139         default:
140                 pr_warn("CPU%d: unhandled IPI%d\n", smp_processor_id(), ipi);
141                 break;
142         }
143
144         return IRQ_HANDLED;
145 }
146
147 void riscv_ipi_enable(void)
148 {
149         int i;
150
151         if (WARN_ON_ONCE(!ipi_virq_base))
152                 return;
153
154         for (i = 0; i < nr_ipi; i++)
155                 enable_percpu_irq(ipi_virq_base + i, 0);
156 }
157
158 void riscv_ipi_disable(void)
159 {
160         int i;
161
162         if (WARN_ON_ONCE(!ipi_virq_base))
163                 return;
164
165         for (i = 0; i < nr_ipi; i++)
166                 disable_percpu_irq(ipi_virq_base + i);
167 }
168
169 bool riscv_ipi_have_virq_range(void)
170 {
171         return (ipi_virq_base) ? true : false;
172 }
173
174 DEFINE_STATIC_KEY_FALSE(riscv_ipi_for_rfence);
175 EXPORT_SYMBOL_GPL(riscv_ipi_for_rfence);
176
177 void riscv_ipi_set_virq_range(int virq, int nr, bool use_for_rfence)
178 {
179         int i, err;
180
181         if (WARN_ON(ipi_virq_base))
182                 return;
183
184         WARN_ON(nr < IPI_MAX);
185         nr_ipi = min(nr, IPI_MAX);
186         ipi_virq_base = virq;
187
188         /* Request IPIs */
189         for (i = 0; i < nr_ipi; i++) {
190                 err = request_percpu_irq(ipi_virq_base + i, handle_IPI,
191                                          "IPI", &ipi_dummy_dev);
192                 WARN_ON(err);
193
194                 ipi_desc[i] = irq_to_desc(ipi_virq_base + i);
195                 irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN);
196         }
197
198         /* Enabled IPIs for boot CPU immediately */
199         riscv_ipi_enable();
200
201         /* Update RFENCE static key */
202         if (use_for_rfence)
203                 static_branch_enable(&riscv_ipi_for_rfence);
204         else
205                 static_branch_disable(&riscv_ipi_for_rfence);
206 }
207
208 static const char * const ipi_names[] = {
209         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
210         [IPI_CALL_FUNC]         = "Function call interrupts",
211         [IPI_CPU_STOP]          = "CPU stop interrupts",
212         [IPI_CPU_CRASH_STOP]    = "CPU stop (for crash dump) interrupts",
213         [IPI_IRQ_WORK]          = "IRQ work interrupts",
214         [IPI_TIMER]             = "Timer broadcast interrupts",
215 };
216
217 void show_ipi_stats(struct seq_file *p, int prec)
218 {
219         unsigned int cpu, i;
220
221         for (i = 0; i < IPI_MAX; i++) {
222                 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
223                            prec >= 4 ? " " : "");
224                 for_each_online_cpu(cpu)
225                         seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
226                 seq_printf(p, " %s\n", ipi_names[i]);
227         }
228 }
229
230 void arch_send_call_function_ipi_mask(struct cpumask *mask)
231 {
232         send_ipi_mask(mask, IPI_CALL_FUNC);
233 }
234
235 void arch_send_call_function_single_ipi(int cpu)
236 {
237         send_ipi_single(cpu, IPI_CALL_FUNC);
238 }
239
240 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
241 void tick_broadcast(const struct cpumask *mask)
242 {
243         send_ipi_mask(mask, IPI_TIMER);
244 }
245 #endif
246
247 void smp_send_stop(void)
248 {
249         unsigned long timeout;
250
251         if (num_online_cpus() > 1) {
252                 cpumask_t mask;
253
254                 cpumask_copy(&mask, cpu_online_mask);
255                 cpumask_clear_cpu(smp_processor_id(), &mask);
256
257                 if (system_state <= SYSTEM_RUNNING)
258                         pr_crit("SMP: stopping secondary CPUs\n");
259                 send_ipi_mask(&mask, IPI_CPU_STOP);
260         }
261
262         /* Wait up to one second for other CPUs to stop */
263         timeout = USEC_PER_SEC;
264         while (num_online_cpus() > 1 && timeout--)
265                 udelay(1);
266
267         if (num_online_cpus() > 1)
268                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
269                            cpumask_pr_args(cpu_online_mask));
270 }
271
272 #ifdef CONFIG_KEXEC_CORE
273 /*
274  * The number of CPUs online, not counting this CPU (which may not be
275  * fully online and so not counted in num_online_cpus()).
276  */
277 static inline unsigned int num_other_online_cpus(void)
278 {
279         unsigned int this_cpu_online = cpu_online(smp_processor_id());
280
281         return num_online_cpus() - this_cpu_online;
282 }
283
284 void crash_smp_send_stop(void)
285 {
286         static int cpus_stopped;
287         cpumask_t mask;
288         unsigned long timeout;
289
290         /*
291          * This function can be called twice in panic path, but obviously
292          * we execute this only once.
293          */
294         if (cpus_stopped)
295                 return;
296
297         cpus_stopped = 1;
298
299         /*
300          * If this cpu is the only one alive at this point in time, online or
301          * not, there are no stop messages to be sent around, so just back out.
302          */
303         if (num_other_online_cpus() == 0)
304                 return;
305
306         cpumask_copy(&mask, cpu_online_mask);
307         cpumask_clear_cpu(smp_processor_id(), &mask);
308
309         atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
310
311         pr_crit("SMP: stopping secondary CPUs\n");
312         send_ipi_mask(&mask, IPI_CPU_CRASH_STOP);
313
314         /* Wait up to one second for other CPUs to stop */
315         timeout = USEC_PER_SEC;
316         while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
317                 udelay(1);
318
319         if (atomic_read(&waiting_for_crash_ipi) > 0)
320                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
321                         cpumask_pr_args(&mask));
322 }
323
324 bool smp_crash_stop_failed(void)
325 {
326         return (atomic_read(&waiting_for_crash_ipi) > 0);
327 }
328 #endif
329
330 void arch_smp_send_reschedule(int cpu)
331 {
332         send_ipi_single(cpu, IPI_RESCHEDULE);
333 }
334 EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);