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 /* A statistic, can be a little off */
  45 int num_reschedules_sent = 0;
  46
  47 /* Not changed after boot */
  48 struct task_struct *idle_threads[NR_CPUS];
  49
  50 void smp_send_reschedule(int cpu)
  51 {
  52         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  53         num_reschedules_sent++;
  54 }
  55
  56 void smp_send_stop(void)
  57 {
  58         int i;
  59
  60         printk(KERN_INFO "Stopping all CPUs...");
  61         for(i = 0; i < num_online_cpus(); i++){
  62                 if(i == current_thread->cpu)
  63                         continue;
  64                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
  65         }
  66         printk("done\n");
  67 }
  68
  69 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
  70 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
  71
  72 static int idle_proc(void *cpup)
  73 {
  74         int cpu = (int) cpup, err;
  75
  76         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
  77         if(err < 0)
  78                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
  79
  80         activate_ipi(cpu_data[cpu].ipi_pipe[0],
  81                      current->thread.mode.tt.extern_pid);
  82
  83         wmb();
  84         if (cpu_test_and_set(cpu, cpu_callin_map)) {
  85                 printk("huh, CPU#%d already present??\n", cpu);
  86                 BUG();
  87         }
  88
  89         while (!cpu_isset(cpu, smp_commenced_mask))
  90                 cpu_relax();
  91
  92         cpu_set(cpu, cpu_online_map);
  93         default_idle();
  94         return(0);
  95 }
  96
  97 static struct task_struct *idle_thread(int cpu)
  98 {
  99         struct task_struct *new_task;
 100         unsigned char c;
 101
 102         current->thread.request.u.thread.proc = idle_proc;
 103         current->thread.request.u.thread.arg = (void *) cpu;
 104         new_task = fork_idle(cpu);
 105         if(IS_ERR(new_task))
 106                 panic("copy_process failed in idle_thread, error = %ld",
 107                       PTR_ERR(new_task));
 108
 109         cpu_tasks[cpu] = ((struct cpu_task)
 110                           { .pid =      new_task->thread.mode.tt.extern_pid,
 111                             .task =     new_task } );
 112         idle_threads[cpu] = new_task;
 113         CHOOSE_MODE(os_write_file(new_task->thread.mode.tt.switch_pipe[1], &c,
 114                           sizeof(c)),
 115                     ({ panic("skas mode doesn't support SMP"); }));
 116         return(new_task);
 117 }
 118
 119 void smp_prepare_cpus(unsigned int maxcpus)
 120 {
 121         struct task_struct *idle;
 122         unsigned long waittime;
 123         int err, cpu, me = smp_processor_id();
 124         int i;
 125
 126         for (i = 0; i < ncpus; ++i)
 127                 cpu_set(i, cpu_possible_map);
 128
 129         cpu_clear(me, cpu_online_map);
 130         cpu_set(me, cpu_online_map);
 131         cpu_set(me, cpu_callin_map);
 132
 133         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 134         if(err < 0)
 135                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 136
 137         activate_ipi(cpu_data[me].ipi_pipe[0],
 138                      current->thread.mode.tt.extern_pid);
 139
 140         for(cpu = 1; cpu < ncpus; cpu++){
 141                 printk("Booting processor %d...\n", cpu);
 142
 143                 idle = idle_thread(cpu);
 144
 145                 init_idle(idle, cpu);
 146                 unhash_process(idle);
 147
 148                 waittime = 200000000;
 149                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 150                         cpu_relax();
 151
 152                 if (cpu_isset(cpu, cpu_callin_map))
 153                         printk("done\n");
 154                 else printk("failed\n");
 155         }
 156 }
 157
 158 void smp_prepare_boot_cpu(void)
 159 {
 160         cpu_set(smp_processor_id(), cpu_online_map);
 161 }
 162
 163 int __cpu_up(unsigned int cpu)
 164 {
 165         cpu_set(cpu, smp_commenced_mask);
 166         while (!cpu_isset(cpu, cpu_online_map))
 167                 mb();
 168         return(0);
 169 }
 170
 171 int setup_profiling_timer(unsigned int multiplier)
 172 {
 173         printk(KERN_INFO "setup_profiling_timer\n");
 174         return(0);
 175 }
 176
 177 void smp_call_function_slave(int cpu);
 178
 179 void IPI_handler(int cpu)
 180 {
 181         unsigned char c;
 182         int fd;
 183
 184         fd = cpu_data[cpu].ipi_pipe[0];
 185         while (os_read_file(fd, &c, 1) == 1) {
 186                 switch (c) {
 187                 case 'C':
 188                         smp_call_function_slave(cpu);
 189                         break;
 190
 191                 case 'R':
 192                         set_tsk_need_resched(current);
 193                         break;
 194
 195                 case 'S':
 196                         printk("CPU#%d stopping\n", cpu);
 197                         while(1)
 198                                 pause();
 199                         break;
 200
 201                 default:
 202                         printk("CPU#%d received unknown IPI [%c]!\n", cpu, c);
 203                         break;
 204                 }
 205         }
 206 }
 207
 208 int hard_smp_processor_id(void)
 209 {
 210         return(pid_to_processor_id(os_getpid()));
 211 }
 212
 213 static DEFINE_SPINLOCK(call_lock);
 214 static atomic_t scf_started;
 215 static atomic_t scf_finished;
 216 static void (*func)(void *info);
 217 static void *info;
 218
 219 void smp_call_function_slave(int cpu)
 220 {
 221         atomic_inc(&scf_started);
 222         (*func)(info);
 223         atomic_inc(&scf_finished);
 224 }
 225
 226 int smp_call_function(void (*_func)(void *info), void *_info, int nonatomic,
 227                       int wait)
 228 {
 229         int cpus = num_online_cpus() - 1;
 230         int i;
 231
 232         if (!cpus)
 233                 return 0;
 234
 235         /* Can deadlock when called with interrupts disabled */
 236         WARN_ON(irqs_disabled());
 237
 238         spin_lock_bh(&call_lock);
 239         atomic_set(&scf_started, 0);
 240         atomic_set(&scf_finished, 0);
 241         func = _func;
 242         info = _info;
 243
 244         for_each_online_cpu(i)
 245                 os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 246
 247         while (atomic_read(&scf_started) != cpus)
 248                 barrier();
 249
 250         if (wait)
 251                 while (atomic_read(&scf_finished) != cpus)
 252                         barrier();
 253
 254         spin_unlock_bh(&call_lock);
 255         return 0;
 256 }
 257
 258 #endif
 259
 260 /*
 261  * Overrides for Emacs so that we follow Linus's tabbing style.
 262  * Emacs will notice this stuff at the end of the file and automatically
 263  * adjust the settings for this buffer only.  This must remain at the end
 264  * of the file.
 265  * ---------------------------------------------------------------------------
 266  * Local variables:
 267  * c-file-style: "linux"
 268  * End:
 269  */