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/percpu.h> 17 #include <linux/profile.h> 18 #include <linux/smp.h> 19 #include <linux/sched.h> 20 #include <linux/seq_file.h> 21 #include <linux/delay.h> 22 #include <linux/irq.h> 23 #include <linux/irq_work.h> 24 25 #include <asm/tlbflush.h> 26 #include <asm/cacheflush.h> 27 #include <asm/cpu_ops.h> 28 29 enum ipi_message_type { 30 IPI_RESCHEDULE, 31 IPI_CALL_FUNC, 32 IPI_CPU_STOP, 33 IPI_CPU_CRASH_STOP, 34 IPI_IRQ_WORK, 35 IPI_TIMER, 36 IPI_MAX 37 }; 38 39 unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = { 40 [0 ... NR_CPUS-1] = INVALID_HARTID 41 }; 42 43 void __init smp_setup_processor_id(void) 44 { 45 cpuid_to_hartid_map(0) = boot_cpu_hartid; 46 } 47 48 static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev); 49 static int ipi_virq_base __ro_after_init; 50 static int nr_ipi __ro_after_init = IPI_MAX; 51 static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly; 52 53 int riscv_hartid_to_cpuid(unsigned long hartid) 54 { 55 int i; 56 57 for (i = 0; i < NR_CPUS; i++) 58 if (cpuid_to_hartid_map(i) == hartid) 59 return i; 60 61 return -ENOENT; 62 } 63 64 bool arch_match_cpu_phys_id(int cpu, u64 phys_id) 65 { 66 return phys_id == cpuid_to_hartid_map(cpu); 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]->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 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(smp_processor_id(), 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 default: 145 pr_warn("CPU%d: unhandled IPI%d\n", smp_processor_id(), ipi); 146 break; 147 } 148 149 return IRQ_HANDLED; 150 } 151 152 void riscv_ipi_enable(void) 153 { 154 int i; 155 156 if (WARN_ON_ONCE(!ipi_virq_base)) 157 return; 158 159 for (i = 0; i < nr_ipi; i++) 160 enable_percpu_irq(ipi_virq_base + i, 0); 161 } 162 163 void riscv_ipi_disable(void) 164 { 165 int i; 166 167 if (WARN_ON_ONCE(!ipi_virq_base)) 168 return; 169 170 for (i = 0; i < nr_ipi; i++) 171 disable_percpu_irq(ipi_virq_base + i); 172 } 173 174 bool riscv_ipi_have_virq_range(void) 175 { 176 return (ipi_virq_base) ? true : false; 177 } 178 179 DEFINE_STATIC_KEY_FALSE(riscv_ipi_for_rfence); 180 EXPORT_SYMBOL_GPL(riscv_ipi_for_rfence); 181 182 void riscv_ipi_set_virq_range(int virq, int nr, bool use_for_rfence) 183 { 184 int i, err; 185 186 if (WARN_ON(ipi_virq_base)) 187 return; 188 189 WARN_ON(nr < IPI_MAX); 190 nr_ipi = min(nr, IPI_MAX); 191 ipi_virq_base = virq; 192 193 /* Request IPIs */ 194 for (i = 0; i < nr_ipi; i++) { 195 err = request_percpu_irq(ipi_virq_base + i, handle_IPI, 196 "IPI", &ipi_dummy_dev); 197 WARN_ON(err); 198 199 ipi_desc[i] = irq_to_desc(ipi_virq_base + i); 200 irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN); 201 } 202 203 /* Enabled IPIs for boot CPU immediately */ 204 riscv_ipi_enable(); 205 206 /* Update RFENCE static key */ 207 if (use_for_rfence) 208 static_branch_enable(&riscv_ipi_for_rfence); 209 else 210 static_branch_disable(&riscv_ipi_for_rfence); 211 } 212 213 static const char * const ipi_names[] = { 214 [IPI_RESCHEDULE] = "Rescheduling interrupts", 215 [IPI_CALL_FUNC] = "Function call interrupts", 216 [IPI_CPU_STOP] = "CPU stop interrupts", 217 [IPI_CPU_CRASH_STOP] = "CPU stop (for crash dump) interrupts", 218 [IPI_IRQ_WORK] = "IRQ work interrupts", 219 [IPI_TIMER] = "Timer broadcast 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