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Linux/arch/um/kernel/smp.c

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  1 /*
  2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  3  * Licensed under the GPL
  4  */
  5 
  6 #include "linux/percpu.h"
  7 #include "asm/pgalloc.h"
  8 #include "asm/tlb.h"
  9 
 10 #ifdef CONFIG_SMP
 11 
 12 #include "linux/sched.h"
 13 #include "linux/module.h"
 14 #include "linux/threads.h"
 15 #include "linux/interrupt.h"
 16 #include "linux/err.h"
 17 #include "linux/hardirq.h"
 18 #include "asm/smp.h"
 19 #include "asm/processor.h"
 20 #include "asm/spinlock.h"
 21 #include "kern.h"
 22 #include "irq_user.h"
 23 #include "os.h"
 24 
 25 /* Per CPU bogomips and other parameters
 26  * The only piece used here is the ipi pipe, which is set before SMP is
 27  * started and never changed.
 28  */
 29 struct cpuinfo_um cpu_data[NR_CPUS];
 30 
 31 /* A statistic, can be a little off */
 32 int num_reschedules_sent = 0;
 33 
 34 /* Not changed after boot */
 35 struct task_struct *idle_threads[NR_CPUS];
 36 
 37 void smp_send_reschedule(int cpu)
 38 {
 39         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
 40         num_reschedules_sent++;
 41 }
 42 
 43 void smp_send_stop(void)
 44 {
 45         int i;
 46 
 47         printk(KERN_INFO "Stopping all CPUs...");
 48         for (i = 0; i < num_online_cpus(); i++) {
 49                 if (i == current_thread->cpu)
 50                         continue;
 51                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
 52         }
 53         printk(KERN_CONT "done\n");
 54 }
 55 
 56 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
 57 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
 58 
 59 static int idle_proc(void *cpup)
 60 {
 61         int cpu = (int) cpup, err;
 62 
 63         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
 64         if (err < 0)
 65                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
 66 
 67         os_set_fd_async(cpu_data[cpu].ipi_pipe[0]);
 68 
 69         wmb();
 70         if (cpu_test_and_set(cpu, cpu_callin_map)) {
 71                 printk(KERN_ERR "huh, CPU#%d already present??\n", cpu);
 72                 BUG();
 73         }
 74 
 75         while (!cpu_isset(cpu, smp_commenced_mask))
 76                 cpu_relax();
 77 
 78         notify_cpu_starting(cpu);
 79         cpu_set(cpu, cpu_online_map);
 80         default_idle();
 81         return 0;
 82 }
 83 
 84 static struct task_struct *idle_thread(int cpu)
 85 {
 86         struct task_struct *new_task;
 87 
 88         current->thread.request.u.thread.proc = idle_proc;
 89         current->thread.request.u.thread.arg = (void *) cpu;
 90         new_task = fork_idle(cpu);
 91         if (IS_ERR(new_task))
 92                 panic("copy_process failed in idle_thread, error = %ld",
 93                       PTR_ERR(new_task));
 94 
 95         cpu_tasks[cpu] = ((struct cpu_task)
 96                           { .pid =      new_task->thread.mode.tt.extern_pid,
 97                             .task =     new_task } );
 98         idle_threads[cpu] = new_task;
 99         panic("skas mode doesn't support SMP");
100         return new_task;
101 }
102 
103 void smp_prepare_cpus(unsigned int maxcpus)
104 {
105         struct task_struct *idle;
106         unsigned long waittime;
107         int err, cpu, me = smp_processor_id();
108         int i;
109 
110         for (i = 0; i < ncpus; ++i)
111                 set_cpu_possible(i, true);
112 
113         cpu_clear(me, cpu_online_map);
114         cpu_set(me, cpu_online_map);
115         cpu_set(me, cpu_callin_map);
116 
117         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
118         if (err < 0)
119                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
120 
121         os_set_fd_async(cpu_data[me].ipi_pipe[0]);
122 
123         for (cpu = 1; cpu < ncpus; cpu++) {
124                 printk(KERN_INFO "Booting processor %d...\n", cpu);
125 
126                 idle = idle_thread(cpu);
127 
128                 init_idle(idle, cpu);
129 
130                 waittime = 200000000;
131                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
132                         cpu_relax();
133 
134                 printk(KERN_INFO "%s\n",
135                        cpu_isset(cpu, cpu_calling_map) ? "done" : "failed");
136         }
137 }
138 
139 void smp_prepare_boot_cpu(void)
140 {
141         cpu_set(smp_processor_id(), cpu_online_map);
142 }
143 
144 int __cpu_up(unsigned int cpu)
145 {
146         cpu_set(cpu, smp_commenced_mask);
147         while (!cpu_isset(cpu, cpu_online_map))
148                 mb();
149         return 0;
150 }
151 
152 int setup_profiling_timer(unsigned int multiplier)
153 {
154         printk(KERN_INFO "setup_profiling_timer\n");
155         return 0;
156 }
157 
158 void smp_call_function_slave(int cpu);
159 
160 void IPI_handler(int cpu)
161 {
162         unsigned char c;
163         int fd;
164 
165         fd = cpu_data[cpu].ipi_pipe[0];
166         while (os_read_file(fd, &c, 1) == 1) {
167                 switch (c) {
168                 case 'C':
169                         smp_call_function_slave(cpu);
170                         break;
171 
172                 case 'R':
173                         scheduler_ipi();
174                         break;
175 
176                 case 'S':
177                         printk(KERN_INFO "CPU#%d stopping\n", cpu);
178                         while (1)
179                                 pause();
180                         break;
181 
182                 default:
183                         printk(KERN_ERR "CPU#%d received unknown IPI [%c]!\n",
184                                cpu, c);
185                         break;
186                 }
187         }
188 }
189 
190 int hard_smp_processor_id(void)
191 {
192         return pid_to_processor_id(os_getpid());
193 }
194 
195 static DEFINE_SPINLOCK(call_lock);
196 static atomic_t scf_started;
197 static atomic_t scf_finished;
198 static void (*func)(void *info);
199 static void *info;
200 
201 void smp_call_function_slave(int cpu)
202 {
203         atomic_inc(&scf_started);
204         (*func)(info);
205         atomic_inc(&scf_finished);
206 }
207 
208 int smp_call_function(void (*_func)(void *info), void *_info, int wait)
209 {
210         int cpus = num_online_cpus() - 1;
211         int i;
212 
213         if (!cpus)
214                 return 0;
215 
216         /* Can deadlock when called with interrupts disabled */
217         WARN_ON(irqs_disabled());
218 
219         spin_lock_bh(&call_lock);
220         atomic_set(&scf_started, 0);
221         atomic_set(&scf_finished, 0);
222         func = _func;
223         info = _info;
224 
225         for_each_online_cpu(i)
226                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
227 
228         while (atomic_read(&scf_started) != cpus)
229                 barrier();
230 
231         if (wait)
232                 while (atomic_read(&scf_finished) != cpus)
233                         barrier();
234 
235         spin_unlock_bh(&call_lock);
236         return 0;
237 }
238 
239 #endif
240 

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