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