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/interrupt.h>
  13 #include <linux/profile.h>
  14 #include <linux/smp.h>
  15 #include <linux/sched.h>
  16 #include <linux/seq_file.h>
  17 #include <linux/delay.h>
  18
  19 #include <asm/clint.h>
  20 #include <asm/sbi.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/cacheflush.h>
  23
  24 enum ipi_message_type {
  25         IPI_RESCHEDULE,
  26         IPI_CALL_FUNC,
  27         IPI_CPU_STOP,
  28         IPI_MAX
  29 };
  30
  31 unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
  32         [0 ... NR_CPUS-1] = INVALID_HARTID
  33 };
  34
  35 void __init smp_setup_processor_id(void)
  36 {
  37         cpuid_to_hartid_map(0) = boot_cpu_hartid;
  38 }
  39
  40 /* A collection of single bit ipi messages.  */
  41 static struct {
  42         unsigned long stats[IPI_MAX] ____cacheline_aligned;
  43         unsigned long bits ____cacheline_aligned;
  44 } ipi_data[NR_CPUS] __cacheline_aligned;
  45
  46 int riscv_hartid_to_cpuid(int hartid)
  47 {
  48         int i;
  49
  50         for (i = 0; i < NR_CPUS; i++)
  51                 if (cpuid_to_hartid_map(i) == hartid)
  52                         return i;
  53
  54         pr_err("Couldn't find cpu id for hartid [%d]\n", hartid);
  55         return i;
  56 }
  57
  58 void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out)
  59 {
  60         int cpu;
  61
  62         cpumask_clear(out);
  63         for_each_cpu(cpu, in)
  64                 cpumask_set_cpu(cpuid_to_hartid_map(cpu), out);
  65 }
  66
  67 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
  68 {
  69         return phys_id == cpuid_to_hartid_map(cpu);
  70 }
  71
  72 /* Unsupported */
  73 int setup_profiling_timer(unsigned int multiplier)
  74 {
  75         return -EINVAL;
  76 }
  77
  78 static void ipi_stop(void)
  79 {
  80         set_cpu_online(smp_processor_id(), false);
  81         while (1)
  82                 wait_for_interrupt();
  83 }
  84
  85 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
  86 {
  87         struct cpumask hartid_mask;
  88         int cpu;
  89
  90         smp_mb__before_atomic();
  91         for_each_cpu(cpu, mask)
  92                 set_bit(op, &ipi_data[cpu].bits);
  93         smp_mb__after_atomic();
  94
  95         riscv_cpuid_to_hartid_mask(mask, &hartid_mask);
  96         if (IS_ENABLED(CONFIG_RISCV_SBI))
  97                 sbi_send_ipi(cpumask_bits(&hartid_mask));
  98         else
  99                 clint_send_ipi_mask(mask);
 100 }
 101
 102 static void send_ipi_single(int cpu, enum ipi_message_type op)
 103 {
 104         int hartid = cpuid_to_hartid_map(cpu);
 105
 106         smp_mb__before_atomic();
 107         set_bit(op, &ipi_data[cpu].bits);
 108         smp_mb__after_atomic();
 109
 110         if (IS_ENABLED(CONFIG_RISCV_SBI))
 111                 sbi_send_ipi(cpumask_bits(cpumask_of(hartid)));
 112         else
 113                 clint_send_ipi_single(hartid);
 114 }
 115
 116 static inline void clear_ipi(void)
 117 {
 118         if (IS_ENABLED(CONFIG_RISCV_SBI))
 119                 csr_clear(CSR_IP, IE_SIE);
 120         else
 121                 clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
 122 }
 123
 124 void riscv_software_interrupt(void)
 125 {
 126         unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
 127         unsigned long *stats = ipi_data[smp_processor_id()].stats;
 128
 129         clear_ipi();
 130
 131         while (true) {
 132                 unsigned long ops;
 133
 134                 /* Order bit clearing and data access. */
 135                 mb();
 136
 137                 ops = xchg(pending_ipis, 0);
 138                 if (ops == 0)
 139                         return;
 140
 141                 if (ops & (1 << IPI_RESCHEDULE)) {
 142                         stats[IPI_RESCHEDULE]++;
 143                         scheduler_ipi();
 144                 }
 145
 146                 if (ops & (1 << IPI_CALL_FUNC)) {
 147                         stats[IPI_CALL_FUNC]++;
 148                         generic_smp_call_function_interrupt();
 149                 }
 150
 151                 if (ops & (1 << IPI_CPU_STOP)) {
 152                         stats[IPI_CPU_STOP]++;
 153                         ipi_stop();
 154                 }
 155
 156                 BUG_ON((ops >> IPI_MAX) != 0);
 157
 158                 /* Order data access and bit testing. */
 159                 mb();
 160         }
 161 }
 162
 163 static const char * const ipi_names[] = {
 164         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 165         [IPI_CALL_FUNC]         = "Function call interrupts",
 166         [IPI_CPU_STOP]          = "CPU stop interrupts",
 167 };
 168
 169 void show_ipi_stats(struct seq_file *p, int prec)
 170 {
 171         unsigned int cpu, i;
 172
 173         for (i = 0; i < IPI_MAX; i++) {
 174                 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
 175                            prec >= 4 ? " " : "");
 176                 for_each_online_cpu(cpu)
 177                         seq_printf(p, "%10lu ", ipi_data[cpu].stats[i]);
 178                 seq_printf(p, " %s\n", ipi_names[i]);
 179         }
 180 }
 181
 182 void arch_send_call_function_ipi_mask(struct cpumask *mask)
 183 {
 184         send_ipi_mask(mask, IPI_CALL_FUNC);
 185 }
 186
 187 void arch_send_call_function_single_ipi(int cpu)
 188 {
 189         send_ipi_single(cpu, IPI_CALL_FUNC);
 190 }
 191
 192 void smp_send_stop(void)
 193 {
 194         unsigned long timeout;
 195
 196         if (num_online_cpus() > 1) {
 197                 cpumask_t mask;
 198
 199                 cpumask_copy(&mask, cpu_online_mask);
 200                 cpumask_clear_cpu(smp_processor_id(), &mask);
 201
 202                 if (system_state <= SYSTEM_RUNNING)
 203                         pr_crit("SMP: stopping secondary CPUs\n");
 204                 send_ipi_mask(&mask, IPI_CPU_STOP);
 205         }
 206
 207         /* Wait up to one second for other CPUs to stop */
 208         timeout = USEC_PER_SEC;
 209         while (num_online_cpus() > 1 && timeout--)
 210                 udelay(1);
 211
 212         if (num_online_cpus() > 1)
 213                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 214                            cpumask_pr_args(cpu_online_mask));
 215 }
 216
 217 void smp_send_reschedule(int cpu)
 218 {
 219         send_ipi_single(cpu, IPI_RESCHEDULE);
 220 }
 221 EXPORT_SYMBOL_GPL(smp_send_reschedule);