smp.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2025 Ant Group
  4 * Author: Tiwei Bie <tiwei.btw@antgroup.com>
  5 */
  6
  7#include <errno.h>
  8#include <pthread.h>
  9#include <signal.h>
 10#include <kern_util.h>
 11#include <um_malloc.h>
 12#include <init.h>
 13#include <os.h>
 14#include <smp.h>
 15#include "internal.h"
 16
 17struct cpu_thread_data {
 18	int cpu;
 19	sigset_t sigset;
 20};
 21
 22static __thread int __curr_cpu;
 23
 24int uml_curr_cpu(void)
 25{
 26	return __curr_cpu;
 27}
 28
 29static pthread_t cpu_threads[CONFIG_NR_CPUS];
 30
 31static void *cpu_thread(void *arg)
 32{
 33	struct cpu_thread_data *data = arg;
 34
 35	__curr_cpu = data->cpu;
 36
 37	uml_start_secondary(data);
 38
 39	return NULL;
 40}
 41
 42int os_start_cpu_thread(int cpu)
 43{
 44	struct cpu_thread_data *data;
 45	sigset_t sigset, oset;
 46	int err;
 47
 48	data = uml_kmalloc(sizeof(*data), UM_GFP_ATOMIC);
 49	if (!data)
 50		return -ENOMEM;
 51
 52	sigfillset(&sigset);
 53	if (sigprocmask(SIG_SETMASK, &sigset, &oset) < 0) {
 54		err = errno;
 55		goto err;
 56	}
 57
 58	data->cpu = cpu;
 59	data->sigset = oset;
 60
 61	err = pthread_create(&cpu_threads[cpu], NULL, cpu_thread, data);
 62	if (sigprocmask(SIG_SETMASK, &oset, NULL) < 0)
 63		panic("Failed to restore the signal mask, errno = %d", errno);
 64	if (err != 0)
 65		goto err;
 66
 67	return 0;
 68
 69err:
 70	kfree(data);
 71	return -err;
 72}
 73
 74void os_start_secondary(void *arg, jmp_buf *switch_buf)
 75{
 76	struct cpu_thread_data *data = arg;
 77
 78	sigaddset(&data->sigset, IPI_SIGNAL);
 79	sigaddset(&data->sigset, SIGIO);
 80
 81	if (sigprocmask(SIG_SETMASK, &data->sigset, NULL) < 0)
 82		panic("Failed to restore the signal mask, errno = %d", errno);
 83
 84	kfree(data);
 85	longjmp(*switch_buf, 1);
 86
 87	/* unreachable */
 88	printk(UM_KERN_ERR "impossible long jump!");
 89	fatal_sigsegv();
 90}
 91
 92int os_send_ipi(int cpu, int vector)
 93{
 94	union sigval value = { .sival_int = vector };
 95
 96	return pthread_sigqueue(cpu_threads[cpu], IPI_SIGNAL, value);
 97}
 98
 99static void __local_ipi_set(int enable)
100{
101	sigset_t sigset;
102
103	sigemptyset(&sigset);
104	sigaddset(&sigset, IPI_SIGNAL);
105
106	if (sigprocmask(enable ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0)
107		panic("%s: sigprocmask failed, errno = %d", __func__, errno);
108}
109
110void os_local_ipi_enable(void)
111{
112	__local_ipi_set(1);
113}
114
115void os_local_ipi_disable(void)
116{
117	__local_ipi_set(0);
118}
119
120static void ipi_sig_handler(int sig, siginfo_t *si, void *uc)
121{
122	int save_errno = errno;
123
124	signals_enabled = 0;
125	um_trace_signals_off();
126
127	uml_ipi_handler(si->si_value.sival_int);
128
129	um_trace_signals_on();
130	signals_enabled = 1;
131
132	errno = save_errno;
133}
134
135void __init os_init_smp(void)
136{
137	struct sigaction action = {
138		.sa_sigaction = ipi_sig_handler,
139		.sa_flags = SA_SIGINFO | SA_ONSTACK | SA_RESTART,
140	};
141
142	sigfillset(&action.sa_mask);
143
144	if (sigaction(IPI_SIGNAL, &action, NULL) < 0)
145		panic("%s: sigaction failed, errno = %d", __func__, errno);
146
147	cpu_threads[0] = pthread_self();
148}