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_CONT "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
  79         wmb();
  80         if (cpu_test_and_set(cpu, cpu_callin_map)) {
  81                 printk(KERN_ERR "huh, CPU#%d already present??\n", cpu);
  82                 BUG();
  83         }
  84
  85         while (!cpu_isset(cpu, smp_commenced_mask))
  86                 cpu_relax();
  87
  88         cpu_set(cpu, cpu_online_map);
  89         default_idle();
  90         return 0;
  91 }
  92
  93 static struct task_struct *idle_thread(int cpu)
  94 {
  95         struct task_struct *new_task;
  96
  97         current->thread.request.u.thread.proc = idle_proc;
  98         current->thread.request.u.thread.arg = (void *) cpu;
  99         new_task = fork_idle(cpu);
 100         if (IS_ERR(new_task))
 101                 panic("copy_process failed in idle_thread, error = %ld",
 102                       PTR_ERR(new_task));
 103
 104         cpu_tasks[cpu] = ((struct cpu_task)
 105                           { .pid =      new_task->thread.mode.tt.extern_pid,
 106                             .task =     new_task } );
 107         idle_threads[cpu] = new_task;
 108         panic("skas mode doesn't support SMP");
 109         return new_task;
 110 }
 111
 112 void smp_prepare_cpus(unsigned int maxcpus)
 113 {
 114         struct task_struct *idle;
 115         unsigned long waittime;
 116         int err, cpu, me = smp_processor_id();
 117         int i;
 118
 119         for (i = 0; i < ncpus; ++i)
 120                 cpu_set(i, cpu_possible_map);
 121
 122         cpu_clear(me, cpu_online_map);
 123         cpu_set(me, cpu_online_map);
 124         cpu_set(me, cpu_callin_map);
 125
 126         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 127         if (err < 0)
 128                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 129
 130         os_set_fd_async(cpu_data[me].ipi_pipe[0]);
 131
 132         for (cpu = 1; cpu < ncpus; cpu++) {
 133                 printk(KERN_INFO "Booting processor %d...\n", cpu);
 134
 135                 idle = idle_thread(cpu);
 136
 137                 init_idle(idle, cpu);
 138
 139                 waittime = 200000000;
 140                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 141                         cpu_relax();
 142
 143                 printk(KERN_INFO "%s\n",
 144                        cpu_isset(cpu, cpu_calling_map) ? "done" : "failed");
 145         }
 146 }
 147
 148 void smp_prepare_boot_cpu(void)
 149 {
 150         cpu_set(smp_processor_id(), cpu_online_map);
 151 }
 152
 153 int __cpu_up(unsigned int cpu)
 154 {
 155         cpu_set(cpu, smp_commenced_mask);
 156         while (!cpu_isset(cpu, cpu_online_map))
 157                 mb();
 158         return 0;
 159 }
 160
 161 int setup_profiling_timer(unsigned int multiplier)
 162 {
 163         printk(KERN_INFO "setup_profiling_timer\n");
 164         return 0;
 165 }
 166
 167 void smp_call_function_slave(int cpu);
 168
 169 void IPI_handler(int cpu)
 170 {
 171         unsigned char c;
 172         int fd;
 173
 174         fd = cpu_data[cpu].ipi_pipe[0];
 175         while (os_read_file(fd, &c, 1) == 1) {
 176                 switch (c) {
 177                 case 'C':
 178                         smp_call_function_slave(cpu);
 179                         break;
 180
 181                 case 'R':
 182                         set_tsk_need_resched(current);
 183                         break;
 184
 185                 case 'S':
 186                         printk(KERN_INFO "CPU#%d stopping\n", cpu);
 187                         while (1)
 188                                 pause();
 189                         break;
 190
 191                 default:
 192                         printk(KERN_ERR "CPU#%d received unknown IPI [%c]!\n",
 193                                cpu, c);
 194                         break;
 195                 }
 196         }
 197 }
 198
 199 int hard_smp_processor_id(void)
 200 {
 201         return pid_to_processor_id(os_getpid());
 202 }
 203
 204 static DEFINE_SPINLOCK(call_lock);
 205 static atomic_t scf_started;
 206 static atomic_t scf_finished;
 207 static void (*func)(void *info);
 208 static void *info;
 209
 210 void smp_call_function_slave(int cpu)
 211 {
 212         atomic_inc(&scf_started);
 213         (*func)(info);
 214         atomic_inc(&scf_finished);
 215 }
 216
 217 int smp_call_function(void (*_func)(void *info), void *_info, int wait)
 218 {
 219         int cpus = num_online_cpus() - 1;
 220         int i;
 221
 222         if (!cpus)
 223                 return 0;
 224
 225         /* Can deadlock when called with interrupts disabled */
 226         WARN_ON(irqs_disabled());
 227
 228         spin_lock_bh(&call_lock);
 229         atomic_set(&scf_started, 0);
 230         atomic_set(&scf_finished, 0);
 231         func = _func;
 232         info = _info;
 233
 234         for_each_online_cpu(i)
 235                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 236
 237         while (atomic_read(&scf_started) != cpus)
 238                 barrier();
 239
 240         if (wait)
 241                 while (atomic_read(&scf_finished) != cpus)
 242                         barrier();
 243
 244         spin_unlock_bh(&call_lock);
 245         return 0;
 246 }
 247
 248 #endif