smpboot.c
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// SPDX-License-Identifier: GPL-2.0-only
/*
* SMP initialisation and IPI support
* Based on arch/arm64/kernel/smp.c
*
* Copyright (C) 2012 ARM Ltd.
* Copyright (C) 2015 Regents of the University of California
* Copyright (C) 2017 SiFive
*/
#include <linux/arch_topology.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/kernel_stat.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
#include <linux/percpu.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/irq.h>
#include <linux/of.h>
#include <linux/sched/task_stack.h>
#include <linux/sched/mm.h>
#include <asm/cpu_ops.h>
#include <asm/irq.h>
#include <asm/mmu_context.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/sbi.h>
#include <asm/smp.h>
#include "head.h"
static DECLARE_COMPLETION(cpu_running);
void __init smp_prepare_boot_cpu(void)
{
init_cpu_topology();
}
void __init smp_prepare_cpus(unsigned int max_cpus)
{
int cpuid;
int ret;
/* This covers non-smp usecase mandated by "nosmp" option */
if (max_cpus == 0)
return;
for_each_possible_cpu(cpuid) {
if (cpuid == smp_processor_id())
continue;
if (cpu_ops[cpuid]->cpu_prepare) {
ret = cpu_ops[cpuid]->cpu_prepare(cpuid);
if (ret)
continue;
}
set_cpu_present(cpuid, true);
}
}
void __init setup_smp(void)
{
struct device_node *dn;
int hart;
bool found_boot_cpu = false;
int cpuid = 1;
cpu_set_ops(0);
for_each_of_cpu_node(dn) {
hart = riscv_of_processor_hartid(dn);
if (hart < 0)
continue;
if (hart == cpuid_to_hartid_map(0)) {
BUG_ON(found_boot_cpu);
found_boot_cpu = 1;
continue;
}
if (cpuid >= NR_CPUS) {
pr_warn("Invalid cpuid [%d] for hartid [%d]\n",
cpuid, hart);
break;
}
cpuid_to_hartid_map(cpuid) = hart;
cpuid++;
}
BUG_ON(!found_boot_cpu);
if (cpuid > nr_cpu_ids)
pr_warn("Total number of cpus [%d] is greater than nr_cpus option value [%d]\n",
cpuid, nr_cpu_ids);
for (cpuid = 1; cpuid < nr_cpu_ids; cpuid++) {
if (cpuid_to_hartid_map(cpuid) != INVALID_HARTID) {
cpu_set_ops(cpuid);
set_cpu_possible(cpuid, true);
}
}
}
static int start_secondary_cpu(int cpu, struct task_struct *tidle)
{
if (cpu_ops[cpu]->cpu_start)
return cpu_ops[cpu]->cpu_start(cpu, tidle);
return -EOPNOTSUPP;
}
int __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
int ret = 0;
tidle->thread_info.cpu = cpu;
ret = start_secondary_cpu(cpu, tidle);
if (!ret) {
wait_for_completion_timeout(&cpu_running,
msecs_to_jiffies(1000));
if (!cpu_online(cpu)) {
pr_crit("CPU%u: failed to come online\n", cpu);
ret = -EIO;
}
} else {
pr_crit("CPU%u: failed to start\n", cpu);
}
return ret;
}
void __init smp_cpus_done(unsigned int max_cpus)
{
}
/*
* C entry point for a secondary processor.
*/
asmlinkage __visible void smp_callin(void)
{
struct mm_struct *mm = &init_mm;
unsigned int curr_cpuid = smp_processor_id();
riscv_clear_ipi();
/* All kernel threads share the same mm context. */
mmgrab(mm);
current->active_mm = mm;
notify_cpu_starting(curr_cpuid);
update_siblings_masks(curr_cpuid);
set_cpu_online(curr_cpuid, 1);
/*
* Remote TLB flushes are ignored while the CPU is offline, so emit
* a local TLB flush right now just in case.
*/
local_flush_tlb_all();
complete(&cpu_running);
/*
* Disable preemption before enabling interrupts, so we don't try to
* schedule a CPU that hasn't actually started yet.
*/
preempt_disable();
local_irq_enable();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}