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(enable: 1);
113}
114
115void os_local_ipi_disable(void)
116{
117 __local_ipi_set(enable: 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}
149

source code of linux/arch/um/os-Linux/smp.c