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:%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 } 236 237 void arch_send_call_function_ipi_mask(struct cpumask *mask) 238 { 239 send_ipi_mask(mask, IPI_CALL_FUNC); 240 } 241 242 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 248 void tick_broadcast(const struct cpumask *mask) 249 { 250 send_ipi_mask(mask, IPI_TIMER); 251 } 252 #endif 253 254 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 */ 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 } 290 291 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 } 330 331 bool smp_crash_stop_failed(void) 332 { 333 return (atomic_read(&waiting_for_crash_ipi) > 0); 334 } 335 #endif 336 337 void arch_smp_send_reschedule(int cpu) 338 { 339 send_ipi_single(cpu, IPI_RESCHEDULE); 340 } 341 EXPORT_SYMBOL_GPL(arch_smp_send_reschedule); 342 343 static void riscv_backtrace_ipi(cpumask_t *mask) 344 { 345 send_ipi_mask(mask, IPI_CPU_BACKTRACE); 346 } 347 348 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 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