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/config.h"
   7 #include "linux/percpu.h"
   8 #include "asm/pgalloc.h"
   9 #include "asm/tlb.h"
  10
  11 /* For some reason, mmu_gathers are referenced when CONFIG_SMP is off. */
  12 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  13
  14 #ifdef CONFIG_SMP
  15
  16 #include "linux/sched.h"
  17 #include "linux/module.h"
  18 #include "linux/threads.h"
  19 #include "linux/interrupt.h"
  20 #include "linux/err.h"
  21 #include "asm/smp.h"
  22 #include "asm/processor.h"
  23 #include "asm/spinlock.h"
  24 #include "asm/hardirq.h"
  25 #include "user_util.h"
  26 #include "kern_util.h"
  27 #include "kern.h"
  28 #include "irq_user.h"
  29 #include "os.h"
  30
  31 /* CPU online map, set by smp_boot_cpus */
  32 unsigned long cpu_online_map = CPU_MASK_NONE;
  33
  34 EXPORT_SYMBOL(cpu_online_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 /* Set when the idlers are all forked */
  43 int smp_threads_ready = 0;
  44
  45 /* A statistic, can be a little off */
  46 int num_reschedules_sent = 0;
  47
  48 /* Small, random number, never changed */
  49 unsigned long cache_decay_ticks = 5;
  50
  51 /* Not changed after boot */
  52 struct task_struct *idle_threads[NR_CPUS];
  53
  54 void smp_send_reschedule(int cpu)
  55 {
  56         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  57         num_reschedules_sent++;
  58 }
  59
  60 void smp_send_stop(void)
  61 {
  62         int i;
  63
  64         printk(KERN_INFO "Stopping all CPUs...");
  65         for(i = 0; i < num_online_cpus(); i++){
  66                 if(i == current_thread->cpu)
  67                         continue;
  68                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
  69         }
  70         printk("done\n");
  71 }
  72
  73 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
  74 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
  75
  76 static int idle_proc(void *cpup)
  77 {
  78         int cpu = (int) cpup, err;
  79
  80         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
  81         if(err < 0)
  82                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
  83
  84         activate_ipi(cpu_data[cpu].ipi_pipe[0],
  85                      current->thread.mode.tt.extern_pid);
  86
  87         wmb();
  88         if (cpu_test_and_set(cpu, cpu_callin_map)) {
  89                 printk("huh, CPU#%d already present??\n", cpu);
  90                 BUG();
  91         }
  92
  93         while (!cpu_isset(cpu, smp_commenced_mask))
  94                 cpu_relax();
  95
  96         cpu_set(cpu, cpu_online_map);
  97         default_idle();
  98         return(0);
  99 }
 100
 101 static struct task_struct *idle_thread(int cpu)
 102 {
 103         struct task_struct *new_task;
 104         unsigned char c;
 105
 106         current->thread.request.u.thread.proc = idle_proc;
 107         current->thread.request.u.thread.arg = (void *) cpu;
 108         new_task = copy_process(CLONE_VM | CLONE_IDLETASK, 0, NULL, 0, NULL,
 109                                 NULL);
 110         if(IS_ERR(new_task))
 111                 panic("copy_process failed in idle_thread, error = %ld",
 112                       PTR_ERR(new_task));
 113
 114         cpu_tasks[cpu] = ((struct cpu_task)
 115                           { .pid =      new_task->thread.mode.tt.extern_pid,
 116                             .task =     new_task } );
 117         idle_threads[cpu] = new_task;
 118         CHOOSE_MODE(os_write_file(new_task->thread.mode.tt.switch_pipe[1], &c,
 119                                   sizeof(c)),
 120         wake_up_forked_process(new_task);
 121         return(new_task);
 122 }
 123
 124 void smp_prepare_cpus(unsigned int maxcpus)
 125 {
 126         struct task_struct *idle;
 127         unsigned long waittime;
 128         int err, cpu, me = smp_processor_id();
 129
 130         cpu_clear(me, cpu_online_map);
 131         cpu_set(me, cpu_online_map);
 132         cpu_set(me, cpu_callin_map);
 133
 134         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 135         if(err < 0)
 136                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 137
 138         activate_ipi(cpu_data[me].ipi_pipe[0],
 139                      current->thread.mode.tt.extern_pid);
 140
 141         for(cpu = 1; cpu < ncpus; cpu++){
 142                 printk("Booting processor %d...\n", cpu);
 143
 144                 idle = idle_thread(cpu);
 145
 146                 init_idle(idle, cpu);
 147                 unhash_process(idle);
 148
 149                 waittime = 200000000;
 150                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 151                         cpu_relax();
 152
 153                 if (cpu_isset(cpu, cpu_callin_map))
 154                         printk("done\n");
 155                 else printk("failed\n");
 156         }
 157 }
 158
 159 void smp_prepare_boot_cpu(void)
 160 {
 161         cpu_set(smp_processor_id(), cpu_online_map);
 162 }
 163
 164 int __cpu_up(unsigned int cpu)
 165 {
 166         cpu_set(cpu, smp_commenced_mask);
 167         while (!cpu_isset(cpu, cpu_online_map))
 168                 mb();
 169         return(0);
 170 }
 171
 172 int setup_profiling_timer(unsigned int multiplier)
 173 {
 174         printk(KERN_INFO "setup_profiling_timer\n");
 175         return(0);
 176 }
 177
 178 void smp_call_function_slave(int cpu);
 179
 180 void IPI_handler(int cpu)
 181 {
 182         unsigned char c;
 183         int fd;
 184
 185         fd = cpu_data[cpu].ipi_pipe[0];
 186         while (os_read_file(fd, &c, 1) == 1) {
 187                 switch (c) {
 188                 case 'C':
 189                         smp_call_function_slave(cpu);
 190                         break;
 191
 192                 case 'R':
 193                         set_tsk_need_resched(current);
 194                         break;
 195
 196                 case 'S':
 197                         printk("CPU#%d stopping\n", cpu);
 198                         while(1)
 199                                 pause();
 200                         break;
 201
 202                 default:
 203                         printk("CPU#%d received unknown IPI [%c]!\n", cpu, c);
 204                         break;
 205                 }
 206         }
 207 }
 208
 209 int hard_smp_processor_id(void)
 210 {
 211         return(pid_to_processor_id(os_getpid()));
 212 }
 213
 214 static spinlock_t call_lock = SPIN_LOCK_UNLOCKED;
 215 static atomic_t scf_started;
 216 static atomic_t scf_finished;
 217 static void (*func)(void *info);
 218 static void *info;
 219
 220 void smp_call_function_slave(int cpu)
 221 {
 222         atomic_inc(&scf_started);
 223         (*func)(info);
 224         atomic_inc(&scf_finished);
 225 }
 226
 227 int smp_call_function(void (*_func)(void *info), void *_info, int nonatomic,
 228                       int wait)
 229 {
 230         int cpus = num_online_cpus() - 1;
 231         int i;
 232
 233         if (!cpus)
 234                 return 0;
 235
 236         /* Can deadlock when called with interrupts disabled */
 237         WARN_ON(irqs_disabled());
 238
 239         spin_lock_bh(&call_lock);
 240         atomic_set(&scf_started, 0);
 241         atomic_set(&scf_finished, 0);
 242         func = _func;
 243         info = _info;
 244
 245         for (i=0;i<NR_CPUS;i++)
 246                 if((i != current_thread->cpu) &&
 247                    cpu_isset(i, cpu_online_map))
 248                         os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 249
 250         while (atomic_read(&scf_started) != cpus)
 251                 barrier();
 252
 253         if (wait)
 254                 while (atomic_read(&scf_finished) != cpus)
 255                         barrier();
 256
 257         spin_unlock_bh(&call_lock);
 258         return 0;
 259 }
 260
 261 #endif
 262
 263 /*
 264  * Overrides for Emacs so that we follow Linus's tabbing style.
 265  * Emacs will notice this stuff at the end of the file and automatically
 266  * adjust the settings for this buffer only.  This must remain at the end
 267  * of the file.
 268  * ---------------------------------------------------------------------------
 269  * Local variables:
 270  * c-file-style: "linux"
 271  * End:
 272  */