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_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(KERN_INFO "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(KERN_ERR "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
  99         current->thread.request.u.thread.proc = idle_proc;
 100         current->thread.request.u.thread.arg = (void *) cpu;
 101         new_task = fork_idle(cpu);
 102         if (IS_ERR(new_task))
 103                 panic("copy_process failed in idle_thread, error = %ld",
 104                       PTR_ERR(new_task));
 105
 106         cpu_tasks[cpu] = ((struct cpu_task)
 107                           { .pid =      new_task->thread.mode.tt.extern_pid,
 108                             .task =     new_task } );
 109         idle_threads[cpu] = new_task;
 110         panic("skas mode doesn't support SMP");
 111         return new_task;
 112 }
 113
 114 void smp_prepare_cpus(unsigned int maxcpus)
 115 {
 116         struct task_struct *idle;
 117         unsigned long waittime;
 118         int err, cpu, me = smp_processor_id();
 119         int i;
 120
 121         for (i = 0; i < ncpus; ++i)
 122                 cpu_set(i, cpu_possible_map);
 123
 124         cpu_clear(me, cpu_online_map);
 125         cpu_set(me, cpu_online_map);
 126         cpu_set(me, cpu_callin_map);
 127
 128         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 129         if (err < 0)
 130                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 131
 132         os_set_fd_async(cpu_data[me].ipi_pipe[0],
 133                      current->thread.mode.tt.extern_pid);
 134
 135         for (cpu = 1; cpu < ncpus; cpu++) {
 136                 printk(KERN_INFO "Booting processor %d...\n", cpu);
 137
 138                 idle = idle_thread(cpu);
 139
 140                 init_idle(idle, cpu);
 141
 142                 waittime = 200000000;
 143                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 144                         cpu_relax();
 145
 146                 if (cpu_isset(cpu, cpu_callin_map))
 147                         printk(KERN_INFO "done\n");
 148                 else printk(KERN_INFO "failed\n");
 149         }
 150 }
 151
 152 void smp_prepare_boot_cpu(void)
 153 {
 154         cpu_set(smp_processor_id(), cpu_online_map);
 155 }
 156
 157 int __cpu_up(unsigned int cpu)
 158 {
 159         cpu_set(cpu, smp_commenced_mask);
 160         while (!cpu_isset(cpu, cpu_online_map))
 161                 mb();
 162         return 0;
 163 }
 164
 165 int setup_profiling_timer(unsigned int multiplier)
 166 {
 167         printk(KERN_INFO "setup_profiling_timer\n");
 168         return 0;
 169 }
 170
 171 void smp_call_function_slave(int cpu);
 172
 173 void IPI_handler(int cpu)
 174 {
 175         unsigned char c;
 176         int fd;
 177
 178         fd = cpu_data[cpu].ipi_pipe[0];
 179         while (os_read_file(fd, &c, 1) == 1) {
 180                 switch (c) {
 181                 case 'C':
 182                         smp_call_function_slave(cpu);
 183                         break;
 184
 185                 case 'R':
 186                         set_tsk_need_resched(current);
 187                         break;
 188
 189                 case 'S':
 190                         printk(KERN_INFO "CPU#%d stopping\n", cpu);
 191                         while (1)
 192                                 pause();
 193                         break;
 194
 195                 default:
 196                         printk(KERN_ERR "CPU#%d received unknown IPI [%c]!\n",
 197                                cpu, c);
 198                         break;
 199                 }
 200         }
 201 }
 202
 203 int hard_smp_processor_id(void)
 204 {
 205         return pid_to_processor_id(os_getpid());
 206 }
 207
 208 static DEFINE_SPINLOCK(call_lock);
 209 static atomic_t scf_started;
 210 static atomic_t scf_finished;
 211 static void (*func)(void *info);
 212 static void *info;
 213
 214 void smp_call_function_slave(int cpu)
 215 {
 216         atomic_inc(&scf_started);
 217         (*func)(info);
 218         atomic_inc(&scf_finished);
 219 }
 220
 221 int smp_call_function(void (*_func)(void *info), void *_info, int nonatomic,
 222                       int wait)
 223 {
 224         int cpus = num_online_cpus() - 1;
 225         int i;
 226
 227         if (!cpus)
 228                 return 0;
 229
 230         /* Can deadlock when called with interrupts disabled */
 231         WARN_ON(irqs_disabled());
 232
 233         spin_lock_bh(&call_lock);
 234         atomic_set(&scf_started, 0);
 235         atomic_set(&scf_finished, 0);
 236         func = _func;
 237         info = _info;
 238
 239         for_each_online_cpu(i)
 240                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 241
 242         while (atomic_read(&scf_started) != cpus)
 243                 barrier();
 244
 245         if (wait)
 246                 while (atomic_read(&scf_finished) != cpus)
 247                         barrier();
 248
 249         spin_unlock_bh(&call_lock);
 250         return 0;
 251 }
 252
 253 #endif