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 pr_err("Couldn't find cpu id for hartid [%lu]\n", hartid); 62 return -ENOENT; 63 } 64 65 bool arch_match_cpu_phys_id(int cpu, u64 phys_id) 66 { 67 return phys_id == cpuid_to_hartid_map(cpu); 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]->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 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(smp_processor_id(), 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 default: 146 pr_warn("CPU%d: unhandled IPI%d\n", smp_processor_id(), ipi); 147 break; 148 } 149 150 return IRQ_HANDLED; 151 } 152 153 void riscv_ipi_enable(void) 154 { 155 int i; 156 157 if (WARN_ON_ONCE(!ipi_virq_base)) 158 return; 159 160 for (i = 0; i < nr_ipi; i++) 161 enable_percpu_irq(ipi_virq_base + i, 0); 162 } 163 164 void riscv_ipi_disable(void) 165 { 166 int i; 167 168 if (WARN_ON_ONCE(!ipi_virq_base)) 169 return; 170 171 for (i = 0; i < nr_ipi; i++) 172 disable_percpu_irq(ipi_virq_base + i); 173 } 174 175 bool riscv_ipi_have_virq_range(void) 176 { 177 return (ipi_virq_base) ? true : false; 178 } 179 180 DEFINE_STATIC_KEY_FALSE(riscv_ipi_for_rfence); 181 EXPORT_SYMBOL_GPL(riscv_ipi_for_rfence); 182 183 void riscv_ipi_set_virq_range(int virq, int nr, bool use_for_rfence) 184 { 185 int i, err; 186 187 if (WARN_ON(ipi_virq_base)) 188 return; 189 190 WARN_ON(nr < IPI_MAX); 191 nr_ipi = min(nr, IPI_MAX); 192 ipi_virq_base = virq; 193 194 /* Request IPIs */ 195 for (i = 0; i < nr_ipi; i++) { 196 err = request_percpu_irq(ipi_virq_base + i, handle_IPI, 197 "IPI", &ipi_dummy_dev); 198 WARN_ON(err); 199 200 ipi_desc[i] = irq_to_desc(ipi_virq_base + i); 201 irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN); 202 } 203 204 /* Enabled IPIs for boot CPU immediately */ 205 riscv_ipi_enable(); 206 207 /* Update RFENCE static key */ 208 if (use_for_rfence) 209 static_branch_enable(&riscv_ipi_for_rfence); 210 else 211 static_branch_disable(&riscv_ipi_for_rfence); 212 } 213 214 static const char * const ipi_names[] = { 215 [IPI_RESCHEDULE] = "Rescheduling interrupts", 216 [IPI_CALL_FUNC] = "Function call interrupts", 217 [IPI_CPU_STOP] = "CPU stop interrupts", 218 [IPI_CPU_CRASH_STOP] = "CPU stop (for crash dump) interrupts", 219 [IPI_IRQ_WORK] = "IRQ work interrupts", 220 [IPI_TIMER] = "Timer broadcast interrupts", 221 }; 222 223 void show_ipi_stats(struct seq_file *p, int prec) 224 { 225 unsigned int cpu, i; 226 227 for (i = 0; i < IPI_MAX; i++) { 228 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i, 229 prec >= 4 ? " " : ""); 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