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/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 "user_util.h"
  25 #include "kern_util.h"
  26 #include "kern.h"
  27 #include "irq_user.h"
  28 #include "os.h"
  29
  30 /* CPU online map, set by smp_boot_cpus */
  31 cpumask_t cpu_online_map = CPU_MASK_NONE;
  32 cpumask_t cpu_possible_map = CPU_MASK_NONE;
  33
  34 EXPORT_SYMBOL(cpu_online_map);
  35 EXPORT_SYMBOL(cpu_possible_map);
  36
  37 /* Per CPU bogomips and other parameters
  38  * The only piece used here is the ipi pipe, which is set before SMP is
  39  * started and never changed.
  40  */
  41 struct cpuinfo_um cpu_data[NR_CPUS];
  42
  43 /* A statistic, can be a little off */
  44 int num_reschedules_sent = 0;
  45
  46 /* Not changed after boot */
  47 struct task_struct *idle_threads[NR_CPUS];
  48
  49 void smp_send_reschedule(int cpu)
  50 {
  51         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  52         num_reschedules_sent++;
  53 }
  54
  55 void smp_send_stop(void)
  56 {
  57         int i;
  58
  59         printk(KERN_INFO "Stopping all CPUs...");
  60         for(i = 0; i < num_online_cpus(); i++){
  61                 if(i == current_thread->cpu)
  62                         continue;
  63                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
  64         }
  65         printk("done\n");
  66 }
  67
  68 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
  69 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
  70
  71 static int idle_proc(void *cpup)
  72 {
  73         int cpu = (int) cpup, err;
  74
  75         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
  76         if(err < 0)
  77                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
  78
  79         os_set_fd_async(cpu_data[cpu].ipi_pipe[0],
  80                      current->thread.mode.tt.extern_pid);
  81
  82         wmb();
  83         if (cpu_test_and_set(cpu, cpu_callin_map)) {
  84                 printk("huh, CPU#%d already present??\n", cpu);
  85                 BUG();
  86         }
  87
  88         while (!cpu_isset(cpu, smp_commenced_mask))
  89                 cpu_relax();
  90
  91         cpu_set(cpu, cpu_online_map);
  92         default_idle();
  93         return(0);
  94 }
  95
  96 static struct task_struct *idle_thread(int cpu)
  97 {
  98         struct task_struct *new_task;
  99         unsigned char c;
 100
 101         current->thread.request.u.thread.proc = idle_proc;
 102         current->thread.request.u.thread.arg = (void *) cpu;
 103         new_task = fork_idle(cpu);
 104         if(IS_ERR(new_task))
 105                 panic("copy_process failed in idle_thread, error = %ld",
 106                       PTR_ERR(new_task));
 107
 108         cpu_tasks[cpu] = ((struct cpu_task)
 109                           { .pid =      new_task->thread.mode.tt.extern_pid,
 110                             .task =     new_task } );
 111         idle_threads[cpu] = new_task;
 112         CHOOSE_MODE(os_write_file(new_task->thread.mode.tt.switch_pipe[1], &c,
 113                           sizeof(c)),
 114                     ({ panic("skas mode doesn't support SMP"); }));
 115         return(new_task);
 116 }
 117
 118 void smp_prepare_cpus(unsigned int maxcpus)
 119 {
 120         struct task_struct *idle;
 121         unsigned long waittime;
 122         int err, cpu, me = smp_processor_id();
 123         int i;
 124
 125         for (i = 0; i < ncpus; ++i)
 126                 cpu_set(i, cpu_possible_map);
 127
 128         cpu_clear(me, cpu_online_map);
 129         cpu_set(me, cpu_online_map);
 130         cpu_set(me, cpu_callin_map);
 131
 132         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 133         if(err < 0)
 134                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 135
 136         os_set_fd_async(cpu_data[me].ipi_pipe[0],
 137                      current->thread.mode.tt.extern_pid);
 138
 139         for(cpu = 1; cpu < ncpus; cpu++){
 140                 printk("Booting processor %d...\n", cpu);
 141
 142                 idle = idle_thread(cpu);
 143
 144                 init_idle(idle, cpu);
 145
 146                 waittime = 200000000;
 147                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 148                         cpu_relax();
 149
 150                 if (cpu_isset(cpu, cpu_callin_map))
 151                         printk("done\n");
 152                 else printk("failed\n");
 153         }
 154 }
 155
 156 void smp_prepare_boot_cpu(void)
 157 {
 158         cpu_set(smp_processor_id(), cpu_online_map);
 159 }
 160
 161 int __cpu_up(unsigned int cpu)
 162 {
 163         cpu_set(cpu, smp_commenced_mask);
 164         while (!cpu_isset(cpu, cpu_online_map))
 165                 mb();
 166         return(0);
 167 }
 168
 169 int setup_profiling_timer(unsigned int multiplier)
 170 {
 171         printk(KERN_INFO "setup_profiling_timer\n");
 172         return(0);
 173 }
 174
 175 void smp_call_function_slave(int cpu);
 176
 177 void IPI_handler(int cpu)
 178 {
 179         unsigned char c;
 180         int fd;
 181
 182         fd = cpu_data[cpu].ipi_pipe[0];
 183         while (os_read_file(fd, &c, 1) == 1) {
 184                 switch (c) {
 185                 case 'C':
 186                         smp_call_function_slave(cpu);
 187                         break;
 188
 189                 case 'R':
 190                         set_tsk_need_resched(current);
 191                         break;
 192
 193                 case 'S':
 194                         printk("CPU#%d stopping\n", cpu);
 195                         while(1)
 196                                 pause();
 197                         break;
 198
 199                 default:
 200                         printk("CPU#%d received unknown IPI [%c]!\n", cpu, c);
 201                         break;
 202                 }
 203         }
 204 }
 205
 206 int hard_smp_processor_id(void)
 207 {
 208         return(pid_to_processor_id(os_getpid()));
 209 }
 210
 211 static DEFINE_SPINLOCK(call_lock);
 212 static atomic_t scf_started;
 213 static atomic_t scf_finished;
 214 static void (*func)(void *info);
 215 static void *info;
 216
 217 void smp_call_function_slave(int cpu)
 218 {
 219         atomic_inc(&scf_started);
 220         (*func)(info);
 221         atomic_inc(&scf_finished);
 222 }
 223
 224 int smp_call_function(void (*_func)(void *info), void *_info, int nonatomic,
 225                       int wait)
 226 {
 227         int cpus = num_online_cpus() - 1;
 228         int i;
 229
 230         if (!cpus)
 231                 return 0;
 232
 233         /* Can deadlock when called with interrupts disabled */
 234         WARN_ON(irqs_disabled());
 235
 236         spin_lock_bh(&call_lock);
 237         atomic_set(&scf_started, 0);
 238         atomic_set(&scf_finished, 0);
 239         func = _func;
 240         info = _info;
 241
 242         for_each_online_cpu(i)
 243                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 244
 245         while (atomic_read(&scf_started) != cpus)
 246                 barrier();
 247
 248         if (wait)
 249                 while (atomic_read(&scf_finished) != cpus)
 250                         barrier();
 251
 252         spin_unlock_bh(&call_lock);
 253         return 0;
 254 }
 255
 256 #endif
 257
 258 /*
 259  * Overrides for Emacs so that we follow Linus's tabbing style.
 260  * Emacs will notice this stuff at the end of the file and automatically
 261  * adjust the settings for this buffer only.  This must remain at the end
 262  * of the file.
 263  * ---------------------------------------------------------------------------
 264  * Local variables:
 265  * c-file-style: "linux"
 266  * End:
 267  */