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 */
  29struct cpuinfo_um cpu_data[NR_CPUS];
  30
  31/* A statistic, can be a little off */
  32int num_reschedules_sent = 0;
  33
  34/* Not changed after boot */
  35struct task_struct *idle_threads[NR_CPUS];
  36
  37void smp_send_reschedule(int cpu)
  38{
  39        os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  40        num_reschedules_sent++;
  41}
  42
  43void 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
  56static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
  57static cpumask_t cpu_callin_map = CPU_MASK_NONE;
  58
  59static 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
  84static 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
 103void 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
 138void smp_prepare_boot_cpu(void)
 139{
 140        set_cpu_online(smp_processor_id(), true);
 141}
 142
 143int __cpu_up(unsigned int cpu)
 144{
 145        cpu_set(cpu, smp_commenced_mask);
 146        while (!cpu_online(cpu))
 147                mb();
 148        return 0;
 149}
 150
 151int setup_profiling_timer(unsigned int multiplier)
 152{
 153        printk(KERN_INFO "setup_profiling_timer\n");
 154        return 0;
 155}
 156
 157void smp_call_function_slave(int cpu);
 158
 159void 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
 189int hard_smp_processor_id(void)
 190{
 191        return pid_to_processor_id(os_getpid());
 192}
 193
 194static DEFINE_SPINLOCK(call_lock);
 195static atomic_t scf_started;
 196static atomic_t scf_finished;
 197static void (*func)(void *info);
 198static void *info;
 199
 200void smp_call_function_slave(int cpu)
 201{
 202        atomic_inc(&scf_started);
 203        (*func)(info);
 204        atomic_inc(&scf_finished);
 205}
 206
 207int 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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