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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         set_cpu_online(cpu, true);
 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         set_cpu_online(me, true);
114         cpu_set(me, cpu_callin_map);
115 
116         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
117         if (err < 0)
118                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
119 
120         os_set_fd_async(cpu_data[me].ipi_pipe[0]);
121 
122         for (cpu = 1; cpu < ncpus; cpu++) {
123                 printk(KERN_INFO "Booting processor %d...\n", cpu);
124 
125                 idle = idle_thread(cpu);
126 
127                 init_idle(idle, cpu);
128 
129                 waittime = 200000000;
130                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
131                         cpu_relax();
132 
133                 printk(KERN_INFO "%s\n",
134                        cpu_isset(cpu, cpu_calling_map) ? "done" : "failed");
135         }
136 }
137 
138 void smp_prepare_boot_cpu(void)
139 {
140         set_cpu_online(smp_processor_id(), true);
141 }
142 
143 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
144 {
145         cpu_set(cpu, smp_commenced_mask);
146         while (!cpu_online(cpu))
147                 mb();
148         return 0;
149 }
150 
151 int setup_profiling_timer(unsigned int multiplier)
152 {
153         printk(KERN_INFO "setup_profiling_timer\n");
154         return 0;
155 }
156 
157 void smp_call_function_slave(int cpu);
158 
159 void IPI_handler(int cpu)
160 {
161         unsigned char c;
162         int fd;
163 
164         fd = cpu_data[cpu].ipi_pipe[0];
165         while (os_read_file(fd, &c, 1) == 1) {
166                 switch (c) {
167                 case 'C':
168                         smp_call_function_slave(cpu);
169                         break;
170 
171                 case 'R':
172                         scheduler_ipi();
173                         break;
174 
175                 case 'S':
176                         printk(KERN_INFO "CPU#%d stopping\n", cpu);
177                         while (1)
178                                 pause();
179                         break;
180 
181                 default:
182                         printk(KERN_ERR "CPU#%d received unknown IPI [%c]!\n",
183                                cpu, c);
184                         break;
185                 }
186         }
187 }
188 
189 int hard_smp_processor_id(void)
190 {
191         return pid_to_processor_id(os_getpid());
192 }
193 
194 static DEFINE_SPINLOCK(call_lock);
195 static atomic_t scf_started;
196 static atomic_t scf_finished;
197 static void (*func)(void *info);
198 static void *info;
199 
200 void smp_call_function_slave(int cpu)
201 {
202         atomic_inc(&scf_started);
203         (*func)(info);
204         atomic_inc(&scf_finished);
205 }
206 
207 int smp_call_function(void (*_func)(void *info), void *_info, int wait)
208 {
209         int cpus = num_online_cpus() - 1;
210         int i;
211 
212         if (!cpus)
213                 return 0;
214 
215         /* Can deadlock when called with interrupts disabled */
216         WARN_ON(irqs_disabled());
217 
218         spin_lock_bh(&call_lock);
219         atomic_set(&scf_started, 0);
220         atomic_set(&scf_finished, 0);
221         func = _func;
222         info = _info;
223 
224         for_each_online_cpu(i)
225                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
226 
227         while (atomic_read(&scf_started) != cpus)
228                 barrier();
229 
230         if (wait)
231                 while (atomic_read(&scf_finished) != cpus)
232                         barrier();
233 
234         spin_unlock_bh(&call_lock);
235         return 0;
236 }
237 
238 #endif
239 

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