arch/um/kernel/smp.c

   1 /*
   2  * Copyright (C) 2000 - 2003 Jeff Dike (jdike@addtoit.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_util.h"
  25 #include "kern.h"
  26 #include "irq_user.h"
  27 #include "os.h"
  28
  29 /* CPU online map, set by smp_boot_cpus */
  30 cpumask_t cpu_online_map = CPU_MASK_NONE;
  31 cpumask_t cpu_possible_map = CPU_MASK_NONE;
  32
  33 EXPORT_SYMBOL(cpu_online_map);
  34 EXPORT_SYMBOL(cpu_possible_map);
  35
  36 /* Per CPU bogomips and other parameters
  37  * The only piece used here is the ipi pipe, which is set before SMP is
  38  * started and never changed.
  39  */
  40 struct cpuinfo_um cpu_data[NR_CPUS];
  41
  42 /* A statistic, can be a little off */
  43 int num_reschedules_sent = 0;
  44
  45 /* Not changed after boot */
  46 struct task_struct *idle_threads[NR_CPUS];
  47
  48 void smp_send_reschedule(int cpu)
  49 {
  50         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  51         num_reschedules_sent++;
  52 }
  53
  54 void smp_send_stop(void)
  55 {
  56         int i;
  57
  58         printk(KERN_INFO "Stopping all CPUs...");
  59         for(i = 0; i < num_online_cpus(); i++){
  60                 if(i == current_thread->cpu)
  61                         continue;
  62                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
  63         }
  64         printk("done\n");
  65 }
  66
  67 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
  68 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
  69
  70 static int idle_proc(void *cpup)
  71 {
  72         int cpu = (int) cpup, err;
  73
  74         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
  75         if(err < 0)
  76                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
  77
  78         os_set_fd_async(cpu_data[cpu].ipi_pipe[0],
  79                      current->thread.mode.tt.extern_pid);
  80
  81         wmb();
  82         if (cpu_test_and_set(cpu, cpu_callin_map)) {
  83                 printk("huh, CPU#%d already present??\n", cpu);
  84                 BUG();
  85         }
  86
  87         while (!cpu_isset(cpu, smp_commenced_mask))
  88                 cpu_relax();
  89
  90         cpu_set(cpu, cpu_online_map);
  91         default_idle();
  92         return 0;
  93 }
  94
  95 static struct task_struct *idle_thread(int cpu)
  96 {
  97         struct task_struct *new_task;
  98         unsigned char c;
  99
 100         current->thread.request.u.thread.proc = idle_proc;
 101         current->thread.request.u.thread.arg = (void *) cpu;
 102         new_task = fork_idle(cpu);
 103         if(IS_ERR(new_task))
 104                 panic("copy_process failed in idle_thread, error = %ld",
 105                       PTR_ERR(new_task));
 106
 107         cpu_tasks[cpu] = ((struct cpu_task)
 108                           { .pid =      new_task->thread.mode.tt.extern_pid,
 109                             .task =     new_task } );
 110         idle_threads[cpu] = new_task;
 111         CHOOSE_MODE(os_write_file(new_task->thread.mode.tt.switch_pipe[1], &c,
 112                                   sizeof(c)),
 113                     ({ panic("skas mode doesn't support SMP"); }));
 114         return new_task;
 115 }
 116
 117 void smp_prepare_cpus(unsigned int maxcpus)
 118 {
 119         struct task_struct *idle;
 120         unsigned long waittime;
 121         int err, cpu, me = smp_processor_id();
 122         int i;
 123
 124         for (i = 0; i < ncpus; ++i)
 125                 cpu_set(i, cpu_possible_map);
 126
 127         cpu_clear(me, cpu_online_map);
 128         cpu_set(me, cpu_online_map);
 129         cpu_set(me, cpu_callin_map);
 130
 131         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 132         if(err < 0)
 133                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 134
 135         os_set_fd_async(cpu_data[me].ipi_pipe[0],
 136                      current->thread.mode.tt.extern_pid);
 137
 138         for(cpu = 1; cpu < ncpus; cpu++){
 139                 printk("Booting processor %d...\n", cpu);
 140
 141                 idle = idle_thread(cpu);
 142
 143                 init_idle(idle, cpu);
 144
 145                 waittime = 200000000;
 146                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 147                         cpu_relax();
 148
 149                 if (cpu_isset(cpu, cpu_callin_map))
 150                         printk("done\n");
 151                 else printk("failed\n");
 152         }
 153 }
 154
 155 void smp_prepare_boot_cpu(void)
 156 {
 157         cpu_set(smp_processor_id(), cpu_online_map);
 158 }
 159
 160 int __cpu_up(unsigned int cpu)
 161 {
 162         cpu_set(cpu, smp_commenced_mask);
 163         while (!cpu_isset(cpu, cpu_online_map))
 164                 mb();
 165         return 0;
 166 }
 167
 168 int setup_profiling_timer(unsigned int multiplier)
 169 {
 170         printk(KERN_INFO "setup_profiling_timer\n");
 171         return 0;
 172 }
 173
 174 void smp_call_function_slave(int cpu);
 175
 176 void IPI_handler(int cpu)
 177 {
 178         unsigned char c;
 179         int fd;
 180
 181         fd = cpu_data[cpu].ipi_pipe[0];
 182         while (os_read_file(fd, &c, 1) == 1) {
 183                 switch (c) {
 184                 case 'C':
 185                         smp_call_function_slave(cpu);
 186                         break;
 187
 188                 case 'R':
 189                         set_tsk_need_resched(current);
 190                         break;
 191
 192                 case 'S':
 193                         printk("CPU#%d stopping\n", cpu);
 194                         while(1)
 195                                 pause();
 196                         break;
 197
 198                 default:
 199                         printk("CPU#%d received unknown IPI [%c]!\n", cpu, c);
 200                         break;
 201                 }
 202         }
 203 }
 204
 205 int hard_smp_processor_id(void)
 206 {
 207         return pid_to_processor_id(os_getpid());
 208 }
 209
 210 static DEFINE_SPINLOCK(call_lock);
 211 static atomic_t scf_started;
 212 static atomic_t scf_finished;
 213 static void (*func)(void *info);
 214 static void *info;
 215
 216 void smp_call_function_slave(int cpu)
 217 {
 218         atomic_inc(&scf_started);
 219         (*func)(info);
 220         atomic_inc(&scf_finished);
 221 }
 222
 223 int smp_call_function(void (*_func)(void *info), void *_info, int nonatomic,
 224                       int wait)
 225 {
 226         int cpus = num_online_cpus() - 1;
 227         int i;
 228
 229         if (!cpus)
 230                 return 0;
 231
 232         /* Can deadlock when called with interrupts disabled */
 233         WARN_ON(irqs_disabled());
 234
 235         spin_lock_bh(&call_lock);
 236         atomic_set(&scf_started, 0);
 237         atomic_set(&scf_finished, 0);
 238         func = _func;
 239         info = _info;
 240
 241         for_each_online_cpu(i)
 242                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 243
 244         while (atomic_read(&scf_started) != cpus)
 245                 barrier();
 246
 247         if (wait)
 248                 while (atomic_read(&scf_finished) != cpus)
 249                         barrier();
 250
 251         spin_unlock_bh(&call_lock);
 252         return 0;
 253 }
 254
 255 #endif