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 static const char * const ipi_names[] = { 32 [IPI_RESCHEDULE] = "Rescheduling interrupts", 33 [IPI_CALL_FUNC] = "Function call interrupts", 34 [IPI_CPU_STOP] = "CPU stop interrupts", 35 [IPI_CPU_CRASH_STOP] = "CPU stop (for crash dump) interrupts", 36 [IPI_IRQ_WORK] = "IRQ work interrupts", 37 [IPI_TIMER] = "Timer broadcast interrupts", 38 [IPI_CPU_BACKTRACE] = "CPU backtrace interrupts", 39 [IPI_KGDB_ROUNDUP] = "KGDB roundup interrupts", 40 }; 41 42 unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = { 43 [0 ... NR_CPUS-1] = INVALID_HARTID 44 }; 45 EXPORT_SYMBOL_GPL(__cpuid_to_hartid_map); 46 47 void __init smp_setup_processor_id(void) 48 { 49 cpuid_to_hartid_map(0) = boot_cpu_hartid; 50 51 pr_info("Booting Linux on hartid %lu\n", boot_cpu_hartid); 52 } 53 54 static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev); 55 static int ipi_virq_base __ro_after_init; 56 static int nr_ipi __ro_after_init = IPI_MAX; 57 static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly; 58 59 int riscv_hartid_to_cpuid(unsigned long hartid) 60 { 61 int i; 62 63 for (i = 0; i < NR_CPUS; i++) 64 if (cpuid_to_hartid_map(i) == hartid) 65 return i; 66 67 return -ENOENT; 68 } 69 70 static void ipi_stop(void) 71 { 72 set_cpu_online(smp_processor_id(), false); 73 while (1) 74 wait_for_interrupt(); 75 } 76 77 #ifdef CONFIG_KEXEC_CORE 78 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0); 79 80 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs) 81 { 82 crash_save_cpu(regs, cpu); 83 84 atomic_dec(&waiting_for_crash_ipi); 85 86 local_irq_disable(); 87 88 #ifdef CONFIG_HOTPLUG_CPU 89 if (cpu_has_hotplug(cpu)) 90 cpu_ops->cpu_stop(); 91 #endif 92 93 for(;;) 94 wait_for_interrupt(); 95 } 96 #else 97 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs) 98 { 99 unreachable(); 100 } 101 #endif 102 103 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op) 104 { 105 __ipi_send_mask(ipi_desc[op], mask); 106 } 107 108 static void send_ipi_single(int cpu, enum ipi_message_type op) 109 { 110 __ipi_send_mask(ipi_desc[op], cpumask_of(cpu)); 111 } 112 113 #ifdef CONFIG_IRQ_WORK 114 void arch_irq_work_raise(void) 115 { 116 send_ipi_single(smp_processor_id(), IPI_IRQ_WORK); 117 } 118 #endif 119 120 static irqreturn_t handle_IPI(int irq, void *data) 121 { 122 unsigned int cpu = smp_processor_id(); 123 int ipi = irq - ipi_virq_base; 124 125 switch (ipi) { 126 case IPI_RESCHEDULE: 127 scheduler_ipi(); 128 break; 129 case IPI_CALL_FUNC: 130 generic_smp_call_function_interrupt(); 131 break; 132 case IPI_CPU_STOP: 133 ipi_stop(); 134 break; 135 case IPI_CPU_CRASH_STOP: 136 ipi_cpu_crash_stop(cpu, get_irq_regs()); 137 break; 138 case IPI_IRQ_WORK: 139 irq_work_run(); 140 break; 141 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST 142 case IPI_TIMER: 143 tick_receive_broadcast(); 144 break; 145 #endif 146 case IPI_CPU_BACKTRACE: 147 nmi_cpu_backtrace(get_irq_regs()); 148 break; 149 case IPI_KGDB_ROUNDUP: 150 kgdb_nmicallback(cpu, get_irq_regs()); 151 break; 152 default: 153 pr_warn("CPU%d: unhandled IPI%d\n", cpu, ipi); 154 break; 155 } 156 157 return IRQ_HANDLED; 158 } 159 160 void riscv_ipi_enable(void) 161 { 162 int i; 163 164 if (WARN_ON_ONCE(!ipi_virq_base)) 165 return; 166 167 for (i = 0; i < nr_ipi; i++) 168 enable_percpu_irq(ipi_virq_base + i, 0); 169 } 170 171 void riscv_ipi_disable(void) 172 { 173 int i; 174 175 if (WARN_ON_ONCE(!ipi_virq_base)) 176 return; 177 178 for (i = 0; i < nr_ipi; i++) 179 disable_percpu_irq(ipi_virq_base + i); 180 } 181 182 bool riscv_ipi_have_virq_range(void) 183 { 184 return (ipi_virq_base) ? true : false; 185 } 186 187 void riscv_ipi_set_virq_range(int virq, int nr) 188 { 189 int i, err; 190 191 if (WARN_ON(ipi_virq_base)) 192 return; 193 194 WARN_ON(nr < IPI_MAX); 195 nr_ipi = min(nr, IPI_MAX); 196 ipi_virq_base = virq; 197 198 /* Request IPIs */ 199 for (i = 0; i < nr_ipi; i++) { 200 err = request_percpu_irq(ipi_virq_base + i, handle_IPI, 201 ipi_names[i], &ipi_dummy_dev); 202 WARN_ON(err); 203 204 ipi_desc[i] = irq_to_desc(ipi_virq_base + i); 205 irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN); 206 } 207 208 /* Enabled IPIs for boot CPU immediately */ 209 riscv_ipi_enable(); 210 } 211 212 void show_ipi_stats(struct seq_file *p, int prec) 213 { 214 unsigned int cpu, i; 215 216 for (i = 0; i < IPI_MAX; i++) { 217 seq_printf(p, "%*s%u:", prec - 1, "IPI", i); 218 for_each_online_cpu(cpu) 219 seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu)); 220 seq_printf(p, " %s\n", ipi_names[i]); 221 } 222 } 223 224 void arch_send_call_function_ipi_mask(struct cpumask *mask) 225 { 226 send_ipi_mask(mask, IPI_CALL_FUNC); 227 } 228 229 void arch_send_call_function_single_ipi(int cpu) 230 { 231 send_ipi_single(cpu, IPI_CALL_FUNC); 232 } 233 234 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST 235 void tick_broadcast(const struct cpumask *mask) 236 { 237 send_ipi_mask(mask, IPI_TIMER); 238 } 239 #endif 240 241 void smp_send_stop(void) 242 { 243 unsigned long timeout; 244 245 if (num_online_cpus() > 1) { 246 cpumask_t mask; 247 248 cpumask_copy(&mask, cpu_online_mask); 249 cpumask_clear_cpu(smp_processor_id(), &mask); 250 251 if (system_state <= SYSTEM_RUNNING) 252 pr_crit("SMP: stopping secondary CPUs\n"); 253 send_ipi_mask(&mask, IPI_CPU_STOP); 254 } 255 256 /* Wait up to one second for other CPUs to stop */ 257 timeout = USEC_PER_SEC; 258 while (num_online_cpus() > 1 && timeout--) 259 udelay(1); 260 261 if (num_online_cpus() > 1) 262 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", 263 cpumask_pr_args(cpu_online_mask)); 264 } 265 266 #ifdef CONFIG_KEXEC_CORE 267 /* 268 * The number of CPUs online, not counting this CPU (which may not be 269 * fully online and so not counted in num_online_cpus()). 270 */ 271 static inline unsigned int num_other_online_cpus(void) 272 { 273 unsigned int this_cpu_online = cpu_online(smp_processor_id()); 274 275 return num_online_cpus() - this_cpu_online; 276 } 277 278 void crash_smp_send_stop(void) 279 { 280 static int cpus_stopped; 281 cpumask_t mask; 282 unsigned long timeout; 283 284 /* 285 * This function can be called twice in panic path, but obviously 286 * we execute this only once. 287 */ 288 if (cpus_stopped) 289 return; 290 291 cpus_stopped = 1; 292 293 /* 294 * If this cpu is the only one alive at this point in time, online or 295 * not, there are no stop messages to be sent around, so just back out. 296 */ 297 if (num_other_online_cpus() == 0) 298 return; 299 300 cpumask_copy(&mask, cpu_online_mask); 301 cpumask_clear_cpu(smp_processor_id(), &mask); 302 303 atomic_set(&waiting_for_crash_ipi, num_other_online_cpus()); 304 305 pr_crit("SMP: stopping secondary CPUs\n"); 306 send_ipi_mask(&mask, IPI_CPU_CRASH_STOP); 307 308 /* Wait up to one second for other CPUs to stop */ 309 timeout = USEC_PER_SEC; 310 while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--) 311 udelay(1); 312 313 if (atomic_read(&waiting_for_crash_ipi) > 0) 314 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", 315 cpumask_pr_args(&mask)); 316 } 317 318 bool smp_crash_stop_failed(void) 319 { 320 return (atomic_read(&waiting_for_crash_ipi) > 0); 321 } 322 #endif 323 324 void arch_smp_send_reschedule(int cpu) 325 { 326 send_ipi_single(cpu, IPI_RESCHEDULE); 327 } 328 EXPORT_SYMBOL_GPL(arch_smp_send_reschedule); 329 330 static void riscv_backtrace_ipi(cpumask_t *mask) 331 { 332 send_ipi_mask(mask, IPI_CPU_BACKTRACE); 333 } 334 335 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) 336 { 337 nmi_trigger_cpumask_backtrace(mask, exclude_cpu, riscv_backtrace_ipi); 338 } 339 340 #ifdef CONFIG_KGDB 341 void kgdb_roundup_cpus(void) 342 { 343 int this_cpu = raw_smp_processor_id(); 344 int cpu; 345 346 for_each_online_cpu(cpu) { 347 /* No need to roundup ourselves */ 348 if (cpu == this_cpu) 349 continue; 350 351 send_ipi_single(cpu, IPI_KGDB_ROUNDUP); 352 } 353 } 354 #endif 355