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 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 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 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 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 109 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs) 110 { 111 unreachable(); 112 } 113 #endif 114 115 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op) 116 { 117 __ipi_send_mask(ipi_desc[op], mask); 118 } 119 120 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 126 void arch_irq_work_raise(void) 127 { 128 send_ipi_single(smp_processor_id(), IPI_IRQ_WORK); 129 } 130 #endif 131 132 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 } 171 172 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 } 182 183 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 } 193 194 bool riscv_ipi_have_virq_range(void) 195 { 196 return (ipi_virq_base) ? true : false; 197 } 198 199 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 } 223 224 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:", prec - 1, "IPI", i); 230 for_each_online_cpu(cpu) 231 seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu)); 232 seq_printf(p, " %s\n", ipi_names[i]); 233 } 234 } 235 236 void arch_send_call_function_ipi_mask(struct cpumask *mask) 237 { 238 send_ipi_mask(mask, IPI_CALL_FUNC); 239 } 240 241 void arch_send_call_function_single_ipi(int cpu) 242 { 243 send_ipi_single(cpu, IPI_CALL_FUNC); 244 } 245 246 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST 247 void tick_broadcast(const struct cpumask *mask) 248 { 249 send_ipi_mask(mask, IPI_TIMER); 250 } 251 #endif 252 253 void smp_send_stop(void) 254 { 255 unsigned long timeout; 256 257 if (num_online_cpus() > 1) { 258 cpumask_t mask; 259 260 cpumask_copy(&mask, cpu_online_mask); 261 cpumask_clear_cpu(smp_processor_id(), &mask); 262 263 if (system_state <= SYSTEM_RUNNING) 264 pr_crit("SMP: stopping secondary CPUs\n"); 265 send_ipi_mask(&mask, IPI_CPU_STOP); 266 } 267 268 /* Wait up to one second for other CPUs to stop */ 269 timeout = USEC_PER_SEC; 270 while (num_online_cpus() > 1 && timeout--) 271 udelay(1); 272 273 if (num_online_cpus() > 1) 274 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", 275 cpumask_pr_args(cpu_online_mask)); 276 } 277 278 #ifdef CONFIG_KEXEC_CORE 279 /* 280 * The number of CPUs online, not counting this CPU (which may not be 281 * fully online and so not counted in num_online_cpus()). 282 */ 283 static inline unsigned int num_other_online_cpus(void) 284 { 285 unsigned int this_cpu_online = cpu_online(smp_processor_id()); 286 287 return num_online_cpus() - this_cpu_online; 288 } 289 290 void crash_smp_send_stop(void) 291 { 292 static int cpus_stopped; 293 cpumask_t mask; 294 unsigned long timeout; 295 296 /* 297 * This function can be called twice in panic path, but obviously 298 * we execute this only once. 299 */ 300 if (cpus_stopped) 301 return; 302 303 cpus_stopped = 1; 304 305 /* 306 * If this cpu is the only one alive at this point in time, online or 307 * not, there are no stop messages to be sent around, so just back out. 308 */ 309 if (num_other_online_cpus() == 0) 310 return; 311 312 cpumask_copy(&mask, cpu_online_mask); 313 cpumask_clear_cpu(smp_processor_id(), &mask); 314 315 atomic_set(&waiting_for_crash_ipi, num_other_online_cpus()); 316 317 pr_crit("SMP: stopping secondary CPUs\n"); 318 send_ipi_mask(&mask, IPI_CPU_CRASH_STOP); 319 320 /* Wait up to one second for other CPUs to stop */ 321 timeout = USEC_PER_SEC; 322 while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--) 323 udelay(1); 324 325 if (atomic_read(&waiting_for_crash_ipi) > 0) 326 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", 327 cpumask_pr_args(&mask)); 328 } 329 330 bool smp_crash_stop_failed(void) 331 { 332 return (atomic_read(&waiting_for_crash_ipi) > 0); 333 } 334 #endif 335 336 void arch_smp_send_reschedule(int cpu) 337 { 338 send_ipi_single(cpu, IPI_RESCHEDULE); 339 } 340 EXPORT_SYMBOL_GPL(arch_smp_send_reschedule); 341 342 static void riscv_backtrace_ipi(cpumask_t *mask) 343 { 344 send_ipi_mask(mask, IPI_CPU_BACKTRACE); 345 } 346 347 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) 348 { 349 nmi_trigger_cpumask_backtrace(mask, exclude_cpu, riscv_backtrace_ipi); 350 } 351 352 #ifdef CONFIG_KGDB 353 void kgdb_roundup_cpus(void) 354 { 355 int this_cpu = raw_smp_processor_id(); 356 int cpu; 357 358 for_each_online_cpu(cpu) { 359 /* No need to roundup ourselves */ 360 if (cpu == this_cpu) 361 continue; 362 363 send_ipi_single(cpu, IPI_KGDB_ROUNDUP); 364 } 365 } 366 #endif 367