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