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         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