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 /* For some reason, mmu_gathers are referenced when CONFIG_SMP is off. */
  11 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  12
  13 #ifdef CONFIG_SMP
  14
  15 #include "linux/sched.h"
  16 #include "linux/module.h"
  17 #include "linux/threads.h"
  18 #include "linux/interrupt.h"
  19 #include "linux/err.h"
  20 #include "linux/hardirq.h"
  21 #include "asm/smp.h"
  22 #include "asm/processor.h"
  23 #include "asm/spinlock.h"
  24 #include "kern.h"
  25 #include "irq_user.h"
  26 #include "os.h"
  27
  28 /* Per CPU bogomips and other parameters
  29  * The only piece used here is the ipi pipe, which is set before SMP is
  30  * started and never changed.
  31  */
  32 struct cpuinfo_um cpu_data[NR_CPUS];
  33
  34 /* A statistic, can be a little off */
  35 int num_reschedules_sent = 0;
  36
  37 /* Not changed after boot */
  38 struct task_struct *idle_threads[NR_CPUS];
  39
  40 void smp_send_reschedule(int cpu)
  41 {
  42         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  43         num_reschedules_sent++;
  44 }
  45
  46 void smp_send_stop(void)
  47 {
  48         int i;
  49
  50         printk(KERN_INFO "Stopping all CPUs...");
  51         for (i = 0; i < num_online_cpus(); i++) {
  52                 if (i == current_thread->cpu)
  53                         continue;
  54                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
  55         }
  56         printk(KERN_CONT "done\n");
  57 }
  58
  59 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
  60 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
  61
  62 static int idle_proc(void *cpup)
  63 {
  64         int cpu = (int) cpup, err;
  65
  66         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
  67         if (err < 0)
  68                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
  69
  70         os_set_fd_async(cpu_data[cpu].ipi_pipe[0]);
  71
  72         wmb();
  73         if (cpu_test_and_set(cpu, cpu_callin_map)) {
  74                 printk(KERN_ERR "huh, CPU#%d already present??\n", cpu);
  75                 BUG();
  76         }
  77
  78         while (!cpu_isset(cpu, smp_commenced_mask))
  79                 cpu_relax();
  80
  81         notify_cpu_starting(cpu);
  82         cpu_set(cpu, cpu_online_map);
  83         default_idle();
  84         return 0;
  85 }
  86
  87 static struct task_struct *idle_thread(int cpu)
  88 {
  89         struct task_struct *new_task;
  90
  91         current->thread.request.u.thread.proc = idle_proc;
  92         current->thread.request.u.thread.arg = (void *) cpu;
  93         new_task = fork_idle(cpu);
  94         if (IS_ERR(new_task))
  95                 panic("copy_process failed in idle_thread, error = %ld",
  96                       PTR_ERR(new_task));
  97
  98         cpu_tasks[cpu] = ((struct cpu_task)
  99                           { .pid =      new_task->thread.mode.tt.extern_pid,
 100                             .task =     new_task } );
 101         idle_threads[cpu] = new_task;
 102         panic("skas mode doesn't support SMP");
 103         return new_task;
 104 }
 105
 106 void smp_prepare_cpus(unsigned int maxcpus)
 107 {
 108         struct task_struct *idle;
 109         unsigned long waittime;
 110         int err, cpu, me = smp_processor_id();
 111         int i;
 112
 113         for (i = 0; i < ncpus; ++i)
 114                 set_cpu_possible(i, true);
 115
 116         cpu_clear(me, cpu_online_map);
 117         cpu_set(me, cpu_online_map);
 118         cpu_set(me, cpu_callin_map);
 119
 120         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 121         if (err < 0)
 122                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 123
 124         os_set_fd_async(cpu_data[me].ipi_pipe[0]);
 125
 126         for (cpu = 1; cpu < ncpus; cpu++) {
 127                 printk(KERN_INFO "Booting processor %d...\n", cpu);
 128
 129                 idle = idle_thread(cpu);
 130
 131                 init_idle(idle, cpu);
 132
 133                 waittime = 200000000;
 134                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 135                         cpu_relax();
 136
 137                 printk(KERN_INFO "%s\n",
 138                        cpu_isset(cpu, cpu_calling_map) ? "done" : "failed");
 139         }
 140 }
 141
 142 void smp_prepare_boot_cpu(void)
 143 {
 144         cpu_set(smp_processor_id(), cpu_online_map);
 145 }
 146
 147 int __cpu_up(unsigned int cpu)
 148 {
 149         cpu_set(cpu, smp_commenced_mask);
 150         while (!cpu_isset(cpu, cpu_online_map))
 151                 mb();
 152         return 0;
 153 }
 154
 155 int setup_profiling_timer(unsigned int multiplier)
 156 {
 157         printk(KERN_INFO "setup_profiling_timer\n");
 158         return 0;
 159 }
 160
 161 void smp_call_function_slave(int cpu);
 162
 163 void IPI_handler(int cpu)
 164 {
 165         unsigned char c;
 166         int fd;
 167
 168         fd = cpu_data[cpu].ipi_pipe[0];
 169         while (os_read_file(fd, &c, 1) == 1) {
 170                 switch (c) {
 171                 case 'C':
 172                         smp_call_function_slave(cpu);
 173                         break;
 174
 175                 case 'R':
 176                         set_tsk_need_resched(current);
 177                         break;
 178
 179                 case 'S':
 180                         printk(KERN_INFO "CPU#%d stopping\n", cpu);
 181                         while (1)
 182                                 pause();
 183                         break;
 184
 185                 default:
 186                         printk(KERN_ERR "CPU#%d received unknown IPI [%c]!\n",
 187                                cpu, c);
 188                         break;
 189                 }
 190         }
 191 }
 192
 193 int hard_smp_processor_id(void)
 194 {
 195         return pid_to_processor_id(os_getpid());
 196 }
 197
 198 static DEFINE_SPINLOCK(call_lock);
 199 static atomic_t scf_started;
 200 static atomic_t scf_finished;
 201 static void (*func)(void *info);
 202 static void *info;
 203
 204 void smp_call_function_slave(int cpu)
 205 {
 206         atomic_inc(&scf_started);
 207         (*func)(info);
 208         atomic_inc(&scf_finished);
 209 }
 210
 211 int smp_call_function(void (*_func)(void *info), void *_info, int wait)
 212 {
 213         int cpus = num_online_cpus() - 1;
 214         int i;
 215
 216         if (!cpus)
 217                 return 0;
 218
 219         /* Can deadlock when called with interrupts disabled */
 220         WARN_ON(irqs_disabled());
 221
 222         spin_lock_bh(&call_lock);
 223         atomic_set(&scf_started, 0);
 224         atomic_set(&scf_finished, 0);
 225         func = _func;
 226         info = _info;
 227
 228         for_each_online_cpu(i)
 229                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 230
 231         while (atomic_read(&scf_started) != cpus)
 232                 barrier();
 233
 234         if (wait)
 235                 while (atomic_read(&scf_finished) != cpus)
 236                         barrier();
 237
 238         spin_unlock_bh(&call_lock);
 239         return 0;
 240 }
 241
 242 #endif