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/module.h>
  14 #include <linux/profile.h>
  15 #include <linux/smp.h>
  16 #include <linux/sched.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/delay.h>
  19
  20 #include <asm/clint.h>
  21 #include <asm/sbi.h>
  22 #include <asm/tlbflush.h>
  23 #include <asm/cacheflush.h>
  24
  25 enum ipi_message_type {
  26         IPI_RESCHEDULE,
  27         IPI_CALL_FUNC,
  28         IPI_CPU_STOP,
  29         IPI_MAX
  30 };
  31
  32 unsigned long __cpuid_to_hartid_map[NR_CPUS] = {
  33         [0 ... NR_CPUS-1] = INVALID_HARTID
  34 };
  35
  36 void __init smp_setup_processor_id(void)
  37 {
  38         cpuid_to_hartid_map(0) = boot_cpu_hartid;
  39 }
  40
  41 /* A collection of single bit ipi messages.  */
  42 static struct {
  43         unsigned long stats[IPI_MAX] ____cacheline_aligned;
  44         unsigned long bits ____cacheline_aligned;
  45 } ipi_data[NR_CPUS] __cacheline_aligned;
  46
  47 int riscv_hartid_to_cpuid(int hartid)
  48 {
  49         int i;
  50
  51         for (i = 0; i < NR_CPUS; i++)
  52                 if (cpuid_to_hartid_map(i) == hartid)
  53                         return i;
  54
  55         pr_err("Couldn't find cpu id for hartid [%d]\n", hartid);
  56         return i;
  57 }
  58
  59 void riscv_cpuid_to_hartid_mask(const struct cpumask *in, struct cpumask *out)
  60 {
  61         int cpu;
  62
  63         cpumask_clear(out);
  64         for_each_cpu(cpu, in)
  65                 cpumask_set_cpu(cpuid_to_hartid_map(cpu), out);
  66 }
  67 EXPORT_SYMBOL_GPL(riscv_cpuid_to_hartid_mask);
  68
  69 bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
  70 {
  71         return phys_id == cpuid_to_hartid_map(cpu);
  72 }
  73
  74 /* Unsupported */
  75 int setup_profiling_timer(unsigned int multiplier)
  76 {
  77         return -EINVAL;
  78 }
  79
  80 static void ipi_stop(void)
  81 {
  82         set_cpu_online(smp_processor_id(), false);
  83         while (1)
  84                 wait_for_interrupt();
  85 }
  86
  87 static void send_ipi_mask(const struct cpumask *mask, enum ipi_message_type op)
  88 {
  89         struct cpumask hartid_mask;
  90         int cpu;
  91
  92         smp_mb__before_atomic();
  93         for_each_cpu(cpu, mask)
  94                 set_bit(op, &ipi_data[cpu].bits);
  95         smp_mb__after_atomic();
  96
  97         riscv_cpuid_to_hartid_mask(mask, &hartid_mask);
  98         if (IS_ENABLED(CONFIG_RISCV_SBI))
  99                 sbi_send_ipi(cpumask_bits(&hartid_mask));
 100         else
 101                 clint_send_ipi_mask(mask);
 102 }
 103
 104 static void send_ipi_single(int cpu, enum ipi_message_type op)
 105 {
 106         int hartid = cpuid_to_hartid_map(cpu);
 107
 108         smp_mb__before_atomic();
 109         set_bit(op, &ipi_data[cpu].bits);
 110         smp_mb__after_atomic();
 111
 112         if (IS_ENABLED(CONFIG_RISCV_SBI))
 113                 sbi_send_ipi(cpumask_bits(cpumask_of(hartid)));
 114         else
 115                 clint_send_ipi_single(hartid);
 116 }
 117
 118 static inline void clear_ipi(void)
 119 {
 120         if (IS_ENABLED(CONFIG_RISCV_SBI))
 121                 csr_clear(CSR_IP, IE_SIE);
 122         else
 123                 clint_clear_ipi(cpuid_to_hartid_map(smp_processor_id()));
 124 }
 125
 126 void riscv_software_interrupt(void)
 127 {
 128         unsigned long *pending_ipis = &ipi_data[smp_processor_id()].bits;
 129         unsigned long *stats = ipi_data[smp_processor_id()].stats;
 130
 131         clear_ipi();
 132
 133         while (true) {
 134                 unsigned long ops;
 135
 136                 /* Order bit clearing and data access. */
 137                 mb();
 138
 139                 ops = xchg(pending_ipis, 0);
 140                 if (ops == 0)
 141                         return;
 142
 143                 if (ops & (1 << IPI_RESCHEDULE)) {
 144                         stats[IPI_RESCHEDULE]++;
 145                         scheduler_ipi();
 146                 }
 147
 148                 if (ops & (1 << IPI_CALL_FUNC)) {
 149                         stats[IPI_CALL_FUNC]++;
 150                         generic_smp_call_function_interrupt();
 151                 }
 152
 153                 if (ops & (1 << IPI_CPU_STOP)) {
 154                         stats[IPI_CPU_STOP]++;
 155                         ipi_stop();
 156                 }
 157
 158                 BUG_ON((ops >> IPI_MAX) != 0);
 159
 160                 /* Order data access and bit testing. */
 161                 mb();
 162         }
 163 }
 164
 165 static const char * const ipi_names[] = {
 166         [IPI_RESCHEDULE]        = "Rescheduling interrupts",
 167         [IPI_CALL_FUNC]         = "Function call interrupts",
 168         [IPI_CPU_STOP]          = "CPU stop interrupts",
 169 };
 170
 171 void show_ipi_stats(struct seq_file *p, int prec)
 172 {
 173         unsigned int cpu, i;
 174
 175         for (i = 0; i < IPI_MAX; i++) {
 176                 seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
 177                            prec >= 4 ? " " : "");
 178                 for_each_online_cpu(cpu)
 179                         seq_printf(p, "%10lu ", ipi_data[cpu].stats[i]);
 180                 seq_printf(p, " %s\n", ipi_names[i]);
 181         }
 182 }
 183
 184 void arch_send_call_function_ipi_mask(struct cpumask *mask)
 185 {
 186         send_ipi_mask(mask, IPI_CALL_FUNC);
 187 }
 188
 189 void arch_send_call_function_single_ipi(int cpu)
 190 {
 191         send_ipi_single(cpu, IPI_CALL_FUNC);
 192 }
 193
 194 void smp_send_stop(void)
 195 {
 196         unsigned long timeout;
 197
 198         if (num_online_cpus() > 1) {
 199                 cpumask_t mask;
 200
 201                 cpumask_copy(&mask, cpu_online_mask);
 202                 cpumask_clear_cpu(smp_processor_id(), &mask);
 203
 204                 if (system_state <= SYSTEM_RUNNING)
 205                         pr_crit("SMP: stopping secondary CPUs\n");
 206                 send_ipi_mask(&mask, IPI_CPU_STOP);
 207         }
 208
 209         /* Wait up to one second for other CPUs to stop */
 210         timeout = USEC_PER_SEC;
 211         while (num_online_cpus() > 1 && timeout--)
 212                 udelay(1);
 213
 214         if (num_online_cpus() > 1)
 215                 pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
 216                            cpumask_pr_args(cpu_online_mask));
 217 }
 218
 219 void smp_send_reschedule(int cpu)
 220 {
 221         send_ipi_single(cpu, IPI_RESCHEDULE);
 222 }
 223 EXPORT_SYMBOL_GPL(smp_send_reschedule);