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 "linux/hardirq.h"
  22 #include "asm/smp.h"
  23 #include "asm/processor.h"
  24 #include "asm/spinlock.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 cpumask_t cpu_online_map = CPU_MASK_NONE;
  33 cpumask_t cpu_possible_map = CPU_MASK_NONE;
  34
  35 EXPORT_SYMBOL(cpu_online_map);
  36 EXPORT_SYMBOL(cpu_possible_map);
  37
  38 /* Per CPU bogomips and other parameters
  39  * The only piece used here is the ipi pipe, which is set before SMP is
  40  * started and never changed.
  41  */
  42 struct cpuinfo_um cpu_data[NR_CPUS];
  43
  44 /* Set when the idlers are all forked */
  45 int smp_threads_ready = 0;
  46
  47 /* A statistic, can be a little off */
  48 int num_reschedules_sent = 0;
  49
  50 /* Small, random number, never changed */
  51 unsigned long cache_decay_ticks = 5;
  52
  53 /* Not changed after boot */
  54 struct task_struct *idle_threads[NR_CPUS];
  55
  56 void smp_send_reschedule(int cpu)
  57 {
  58         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  59         num_reschedules_sent++;
  60 }
  61
  62 void smp_send_stop(void)
  63 {
  64         int i;
  65
  66         printk(KERN_INFO "Stopping all CPUs...");
  67         for(i = 0; i < num_online_cpus(); i++){
  68                 if(i == current_thread->cpu)
  69                         continue;
  70                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
  71         }
  72         printk("done\n");
  73 }
  74
  75 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
  76 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
  77
  78 static int idle_proc(void *cpup)
  79 {
  80         int cpu = (int) cpup, err;
  81
  82         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
  83         if(err < 0)
  84                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
  85
  86         activate_ipi(cpu_data[cpu].ipi_pipe[0],
  87                      current->thread.mode.tt.extern_pid);
  88
  89         wmb();
  90         if (cpu_test_and_set(cpu, cpu_callin_map)) {
  91                 printk("huh, CPU#%d already present??\n", cpu);
  92                 BUG();
  93         }
  94
  95         while (!cpu_isset(cpu, smp_commenced_mask))
  96                 cpu_relax();
  97
  98         cpu_set(cpu, cpu_online_map);
  99         default_idle();
 100         return(0);
 101 }
 102
 103 static struct task_struct *idle_thread(int cpu)
 104 {
 105         struct task_struct *new_task;
 106         unsigned char c;
 107
 108         current->thread.request.u.thread.proc = idle_proc;
 109         current->thread.request.u.thread.arg = (void *) cpu;
 110         new_task = fork_idle(cpu);
 111         if(IS_ERR(new_task))
 112                 panic("copy_process failed in idle_thread, error = %ld",
 113                       PTR_ERR(new_task));
 114
 115         cpu_tasks[cpu] = ((struct cpu_task)
 116                           { .pid =      new_task->thread.mode.tt.extern_pid,
 117                             .task =     new_task } );
 118         idle_threads[cpu] = new_task;
 119         CHOOSE_MODE(os_write_file(new_task->thread.mode.tt.switch_pipe[1], &c,
 120                           sizeof(c)),
 121                     ({ panic("skas mode doesn't support SMP"); }));
 122         return(new_task);
 123 }
 124
 125 void smp_prepare_cpus(unsigned int maxcpus)
 126 {
 127         struct task_struct *idle;
 128         unsigned long waittime;
 129         int err, cpu, me = smp_processor_id();
 130         int i;
 131
 132         for (i = 0; i < ncpus; ++i)
 133                 cpu_set(i, cpu_possible_map);
 134
 135         cpu_clear(me, cpu_online_map);
 136         cpu_set(me, cpu_online_map);
 137         cpu_set(me, cpu_callin_map);
 138
 139         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 140         if(err < 0)
 141                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 142
 143         activate_ipi(cpu_data[me].ipi_pipe[0],
 144                      current->thread.mode.tt.extern_pid);
 145
 146         for(cpu = 1; cpu < ncpus; cpu++){
 147                 printk("Booting processor %d...\n", cpu);
 148
 149                 idle = idle_thread(cpu);
 150
 151                 init_idle(idle, cpu);
 152                 unhash_process(idle);
 153
 154                 waittime = 200000000;
 155                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 156                         cpu_relax();
 157
 158                 if (cpu_isset(cpu, cpu_callin_map))
 159                         printk("done\n");
 160                 else printk("failed\n");
 161         }
 162 }
 163
 164 void smp_prepare_boot_cpu(void)
 165 {
 166         cpu_set(smp_processor_id(), cpu_online_map);
 167 }
 168
 169 int __cpu_up(unsigned int cpu)
 170 {
 171         cpu_set(cpu, smp_commenced_mask);
 172         while (!cpu_isset(cpu, cpu_online_map))
 173                 mb();
 174         return(0);
 175 }
 176
 177 int setup_profiling_timer(unsigned int multiplier)
 178 {
 179         printk(KERN_INFO "setup_profiling_timer\n");
 180         return(0);
 181 }
 182
 183 void smp_call_function_slave(int cpu);
 184
 185 void IPI_handler(int cpu)
 186 {
 187         unsigned char c;
 188         int fd;
 189
 190         fd = cpu_data[cpu].ipi_pipe[0];
 191         while (os_read_file(fd, &c, 1) == 1) {
 192                 switch (c) {
 193                 case 'C':
 194                         smp_call_function_slave(cpu);
 195                         break;
 196
 197                 case 'R':
 198                         set_tsk_need_resched(current);
 199                         break;
 200
 201                 case 'S':
 202                         printk("CPU#%d stopping\n", cpu);
 203                         while(1)
 204                                 pause();
 205                         break;
 206
 207                 default:
 208                         printk("CPU#%d received unknown IPI [%c]!\n", cpu, c);
 209                         break;
 210                 }
 211         }
 212 }
 213
 214 int hard_smp_processor_id(void)
 215 {
 216         return(pid_to_processor_id(os_getpid()));
 217 }
 218
 219 static spinlock_t call_lock = SPIN_LOCK_UNLOCKED;
 220 static atomic_t scf_started;
 221 static atomic_t scf_finished;
 222 static void (*func)(void *info);
 223 static void *info;
 224
 225 void smp_call_function_slave(int cpu)
 226 {
 227         atomic_inc(&scf_started);
 228         (*func)(info);
 229         atomic_inc(&scf_finished);
 230 }
 231
 232 int smp_call_function(void (*_func)(void *info), void *_info, int nonatomic,
 233                       int wait)
 234 {
 235         int cpus = num_online_cpus() - 1;
 236         int i;
 237
 238         if (!cpus)
 239                 return 0;
 240
 241         /* Can deadlock when called with interrupts disabled */
 242         WARN_ON(irqs_disabled());
 243
 244         spin_lock_bh(&call_lock);
 245         atomic_set(&scf_started, 0);
 246         atomic_set(&scf_finished, 0);
 247         func = _func;
 248         info = _info;
 249
 250         for (i=0;i<NR_CPUS;i++)
 251                 if((i != current_thread->cpu) &&
 252                    cpu_isset(i, cpu_online_map))
 253                         os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 254
 255         while (atomic_read(&scf_started) != cpus)
 256                 barrier();
 257
 258         if (wait)
 259                 while (atomic_read(&scf_finished) != cpus)
 260                         barrier();
 261
 262         spin_unlock_bh(&call_lock);
 263         return 0;
 264 }
 265
 266 #endif
 267
 268 /*
 269  * Overrides for Emacs so that we follow Linus's tabbing style.
 270  * Emacs will notice this stuff at the end of the file and automatically
 271  * adjust the settings for this buffer only.  This must remain at the end
 272  * of the file.
 273  * ---------------------------------------------------------------------------
 274  * Local variables:
 275  * c-file-style: "linux"
 276  * End:
 277  */