arch/um/kernel/smp.c

   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