arch/riscv/kernel/smp.c

   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 unsigned long __cpuid_to_hartid_map[NR_CPUS] __ro_after_init = {
  44         [0 ... NR_CPUS-1] = INVALID_HARTID
  45 };
  46
  47 void __init smp_setup_processor_id(void)
  48 {
  49         cpuid_to_hartid_map(0) = boot_cpu_hartid;
  50 }
  51
  52 static DEFINE_PER_CPU_READ_MOSTLY(int, ipi_dummy_dev);
  53 static int ipi_virq_base __ro_after_init;
  54 static int nr_ipi __ro_after_init = IPI_MAX;
  55 static struct irq_desc *ipi_desc[IPI_MAX] __read_mostly;
  56
  57 int riscv_hartid_to_cpuid(unsigned long hartid)
  58 {
  59         int i;
  60
  61         for (i = 0; i < NR_CPUS; i++)
  62                 if (cpuid_to_hartid_map(i) == hartid)
  63                         return i;
  64
  65         return -ENOENT;
  66 }
  67
  68 static void ipi_stop(void)
  69 {
  70         set_cpu_online(smp_processor_id(), false);
  71         while (1)
  72                 wait_for_interrupt();
  73 }
  74
  75 #ifdef CONFIG_KEXEC_CORE
  76 static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
  77
  78 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
  79 {
  80         crash_save_cpu(regs, cpu);
  81
  82         atomic_dec(&waiting_for_crash_ipi);
  83
  84         local_irq_disable();
  85
  86 #ifdef CONFIG_HOTPLUG_CPU
  87         if (cpu_has_hotplug(cpu))
  88                 cpu_ops->cpu_stop();
  89 #endif
  90
  91         for(;;)
  92                 wait_for_interrupt();
  93 }
  94 #else
  95 static inline void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
  96 {
  97         unreachable();
  98 }
  99 #endif
 100
 101 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
 102 {
 103         __ipi_send_mask(ipi_desc[op], mask);
 104 }
 105
 106 static void send_ipi_single(int cpu, enum ipi_message_type op)
 107 {
 108         __ipi_send_mask(ipi_desc[op], cpumask_of(cpu));
 109 }
 110
 111 #ifdef CONFIG_IRQ_WORK
 112 void arch_irq_work_raise(void)
 113 {
 114         send_ipi_single(smp_processor_id(), IPI_IRQ_WORK);
 115 }
 116 #endif
 117
 118 static irqreturn_t handle_IPI(int irq, void *data)
 119 {
 120         unsigned int cpu = smp_processor_id();
 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(cpu, 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         case IPI_CPU_BACKTRACE:
 145                 nmi_cpu_backtrace(get_irq_regs());
 146                 break;
 147         case IPI_KGDB_ROUNDUP:
 148                 kgdb_nmicallback(cpu, get_irq_regs());
 149                 break;
 150         default:
 151                 pr_warn("CPU%d: unhandled IPI%d\n", cpu, ipi);
 152                 break;
 153         }
 154
 155         return IRQ_HANDLED;
 156 }
 157
 158 void riscv_ipi_enable(void)
 159 {
 160         int i;
 161
 162         if (WARN_ON_ONCE(!ipi_virq_base))
 163                 return;
 164
 165         for (i = 0; i < nr_ipi; i++)
 166                 enable_percpu_irq(ipi_virq_base + i, 0);
 167 }
 168
 169 void riscv_ipi_disable(void)
 170 {
 171         int i;
 172
 173         if (WARN_ON_ONCE(!ipi_virq_base))
 174                 return;
 175
 176         for (i = 0; i < nr_ipi; i++)
 177                 disable_percpu_irq(ipi_virq_base + i);
 178 }
 179
 180 bool riscv_ipi_have_virq_range(void)
 181 {
 182         return (ipi_virq_base) ? true : false;
 183 }
 184
 185 void riscv_ipi_set_virq_range(int virq, int nr)
 186 {
 187         int i, err;
 188
 189         if (WARN_ON(ipi_virq_base))
 190                 return;
 191
 192         WARN_ON(nr < IPI_MAX);
 193         nr_ipi = min(nr, IPI_MAX);
 194         ipi_virq_base = virq;
 195
 196         /* Request IPIs */
 197         for (i = 0; i < nr_ipi; i++) {
 198                 err = request_percpu_irq(ipi_virq_base + i, handle_IPI,
 199                                          "IPI", &ipi_dummy_dev);
 200                 WARN_ON(err);
 201
 202                 ipi_desc[i] = irq_to_desc(ipi_virq_base + i);
 203                 irq_set_status_flags(ipi_virq_base + i, IRQ_HIDDEN);
 204         }
 205
 206         /* Enabled IPIs for boot CPU immediately */
 207         riscv_ipi_enable();
 208 }
 209
 210 static const char * const ipi_names[] = {
 211         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 212         [IPI_CALL_FUNC]         = "Function call interrupts",
 213         [IPI_CPU_STOP]          = "CPU stop interrupts",
 214         [IPI_CPU_CRASH_STOP]    = "CPU stop (for crash dump) interrupts",
 215         [IPI_IRQ_WORK]          = "IRQ work interrupts",
 216         [IPI_TIMER]             = "Timer broadcast interrupts",
 217         [IPI_CPU_BACKTRACE]     = "CPU backtrace interrupts",
 218         [IPI_KGDB_ROUNDUP]      = "KGDB roundup interrupts",
 219 };
 220
 221 void show_ipi_stats(struct seq_file *p, int prec)
 222 {
 223         unsigned int cpu, i;
 224
 225         for (i = 0; i < IPI_MAX; i++) {
 226                 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
 227                            prec >= 4 ? " " : "");
 228                 for_each_online_cpu(cpu)
 229                         seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu));
 230                 seq_printf(p, " %s\n", ipi_names[i]);
 231         }
 232 }
 233
 234 void arch_send_call_function_ipi_mask(struct cpumask *mask)
 235 {
 236         send_ipi_mask(mask, IPI_CALL_FUNC);
 237 }
 238
 239 void arch_send_call_function_single_ipi(int cpu)
 240 {
 241         send_ipi_single(cpu, IPI_CALL_FUNC);
 242 }
 243
 244 #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
 245 void tick_broadcast(const struct cpumask *mask)
 246 {
 247         send_ipi_mask(mask, IPI_TIMER);
 248 }
 249 #endif
 250
 251 void smp_send_stop(void)
 252 {
 253         unsigned long timeout;
 254
 255         if (num_online_cpus() > 1) {
 256                 cpumask_t mask;
 257
 258                 cpumask_copy(&mask, cpu_online_mask);
 259                 cpumask_clear_cpu(smp_processor_id(), &mask);
 260
 261                 if (system_state <= SYSTEM_RUNNING)
 262                         pr_crit("SMP: stopping secondary CPUs\n");
 263                 send_ipi_mask(&mask, IPI_CPU_STOP);
 264         }
 265
 266         /* Wait up to one second for other CPUs to stop */
 267         timeout = USEC_PER_SEC;
 268         while (num_online_cpus() > 1 && timeout--)
 269                 udelay(1);
 270
 271         if (num_online_cpus() > 1)
 272                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 273                            cpumask_pr_args(cpu_online_mask));
 274 }
 275
 276 #ifdef CONFIG_KEXEC_CORE
 277 /*
 278  * The number of CPUs online, not counting this CPU (which may not be
 279  * fully online and so not counted in num_online_cpus()).
 280  */
 281 static inline unsigned int num_other_online_cpus(void)
 282 {
 283         unsigned int this_cpu_online = cpu_online(smp_processor_id());
 284
 285         return num_online_cpus() - this_cpu_online;
 286 }
 287
 288 void crash_smp_send_stop(void)
 289 {
 290         static int cpus_stopped;
 291         cpumask_t mask;
 292         unsigned long timeout;
 293
 294         /*
 295          * This function can be called twice in panic path, but obviously
 296          * we execute this only once.
 297          */
 298         if (cpus_stopped)
 299                 return;
 300
 301         cpus_stopped = 1;
 302
 303         /*
 304          * If this cpu is the only one alive at this point in time, online or
 305          * not, there are no stop messages to be sent around, so just back out.
 306          */
 307         if (num_other_online_cpus() == 0)
 308                 return;
 309
 310         cpumask_copy(&mask, cpu_online_mask);
 311         cpumask_clear_cpu(smp_processor_id(), &mask);
 312
 313         atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
 314
 315         pr_crit("SMP: stopping secondary CPUs\n");
 316         send_ipi_mask(&mask, IPI_CPU_CRASH_STOP);
 317
 318         /* Wait up to one second for other CPUs to stop */
 319         timeout = USEC_PER_SEC;
 320         while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
 321                 udelay(1);
 322
 323         if (atomic_read(&waiting_for_crash_ipi) > 0)
 324                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 325                         cpumask_pr_args(&mask));
 326 }
 327
 328 bool smp_crash_stop_failed(void)
 329 {
 330         return (atomic_read(&waiting_for_crash_ipi) > 0);
 331 }
 332 #endif
 333
 334 void arch_smp_send_reschedule(int cpu)
 335 {
 336         send_ipi_single(cpu, IPI_RESCHEDULE);
 337 }
 338 EXPORT_SYMBOL_GPL(arch_smp_send_reschedule);
 339
 340 static void riscv_backtrace_ipi(cpumask_t *mask)
 341 {
 342         send_ipi_mask(mask, IPI_CPU_BACKTRACE);
 343 }
 344
 345 void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
 346 {
 347         nmi_trigger_cpumask_backtrace(mask, exclude_cpu, riscv_backtrace_ipi);
 348 }
 349
 350 #ifdef CONFIG_KGDB
 351 void kgdb_roundup_cpus(void)
 352 {
 353         int this_cpu = raw_smp_processor_id();
 354         int cpu;
 355
 356         for_each_online_cpu(cpu) {
 357                 /* No need to roundup ourselves */
 358                 if (cpu == this_cpu)
 359                         continue;
 360
 361                 send_ipi_single(cpu, IPI_KGDB_ROUNDUP);
 362         }
 363 }
 364 #endif