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