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 spinlock_t um_bh_lock = SPIN_LOCK_UNLOCKED;
  43
  44 atomic_t global_bh_count;
  45
  46 /* Not used by UML */
  47 unsigned char global_irq_holder = NO_PROC_ID;
  48 unsigned volatile long global_irq_lock;
  49
  50 /* Set when the idlers are all forked */
  51 int smp_threads_ready = 0;
  52
  53 /* A statistic, can be a little off */
  54 int num_reschedules_sent = 0;
  55
  56 /* Small, random number, never changed */
  57 unsigned long cache_decay_ticks = 5;
  58
  59 /* Not changed after boot */
  60 struct task_struct *idle_threads[NR_CPUS];
  61
  62 void smp_send_reschedule(int cpu)
  63 {
  64         os_write_file(cpu_data[cpu].ipi_pipe[1], "R", 1);
  65         num_reschedules_sent++;
  66 }
  67
  68 static void show(char * str)
  69 {
  70         int cpu = smp_processor_id();
  71
  72         printk(KERN_INFO "\n%s, CPU %d:\n", str, cpu);
  73 }
  74
  75 #define MAXCOUNT 100000000
  76
  77 static inline void wait_on_bh(void)
  78 {
  79         int count = MAXCOUNT;
  80         do {
  81                 if (!--count) {
  82                         show("wait_on_bh");
  83                         count = ~0;
  84                 }
  85                 /* nothing .. wait for the other bh's to go away */
  86         } while (atomic_read(&global_bh_count) != 0);
  87 }
  88
  89 /*
  90  * This is called when we want to synchronize with
  91  * bottom half handlers. We need to wait until
  92  * no other CPU is executing any bottom half handler.
  93  *
  94  * Don't wait if we're already running in an interrupt
  95  * context or are inside a bh handler.
  96  */
  97 void synchronize_bh(void)
  98 {
  99         if (atomic_read(&global_bh_count) && !in_interrupt())
 100                 wait_on_bh();
 101 }
 102
 103 void smp_send_stop(void)
 104 {
 105         int i;
 106
 107         printk(KERN_INFO "Stopping all CPUs...");
 108         for(i = 0; i < num_online_cpus(); i++){
 109                 if(i == current_thread->cpu)
 110                         continue;
 111                 os_write_file(cpu_data[i].ipi_pipe[1], "S", 1);
 112         }
 113         printk("done\n");
 114 }
 115
 116 static cpumask_t smp_commenced_mask = CPU_MASK_NONE;
 117 static cpumask_t cpu_callin_map = CPU_MASK_NONE;
 118
 119 static int idle_proc(void *cpup)
 120 {
 121         int cpu = (int) cpup, err;
 122
 123         err = os_pipe(cpu_data[cpu].ipi_pipe, 1, 1);
 124         if(err < 0)
 125                 panic("CPU#%d failed to create IPI pipe, err = %d", cpu, -err);
 126
 127         activate_ipi(cpu_data[cpu].ipi_pipe[0],
 128                      current->thread.mode.tt.extern_pid);
 129
 130         wmb();
 131         if (cpu_test_and_set(cpu, cpu_callin_map)) {
 132                 printk("huh, CPU#%d already present??\n", cpu);
 133                 BUG();
 134         }
 135
 136         while (!cpu_isset(cpu, smp_commenced_mask))
 137                 cpu_relax();
 138
 139         cpu_set(cpu, cpu_online_map);
 140         default_idle();
 141         return(0);
 142 }
 143
 144 static struct task_struct *idle_thread(int cpu)
 145 {
 146         struct task_struct *new_task;
 147         unsigned char c;
 148
 149         current->thread.request.u.thread.proc = idle_proc;
 150         current->thread.request.u.thread.arg = (void *) cpu;
 151         new_task = copy_process(CLONE_VM | CLONE_IDLETASK, 0, NULL, 0, NULL,
 152                                 NULL);
 153         if(IS_ERR(new_task))
 154                 panic("copy_process failed in idle_thread, error = %ld",
 155                       PTR_ERR(new_task));
 156
 157         cpu_tasks[cpu] = ((struct cpu_task)
 158                           { .pid =      new_task->thread.mode.tt.extern_pid,
 159                             .task =     new_task } );
 160         idle_threads[cpu] = new_task;
 161         CHOOSE_MODE(os_write_file(new_task->thread.mode.tt.switch_pipe[1], &c,
 162                           sizeof(c)),
 163                     ({ panic("skas mode doesn't support SMP"); }));
 164         wake_up_forked_process(new_task);
 165         return(new_task);
 166 }
 167
 168 void smp_prepare_cpus(unsigned int maxcpus)
 169 {
 170         struct task_struct *idle;
 171         unsigned long waittime;
 172         int err, cpu, me = smp_processor_id();
 173
 174         cpu_clear(me, cpu_online_map);
 175         cpu_set(me, cpu_online_map);
 176         cpu_set(me, cpu_callin_map);
 177
 178         err = os_pipe(cpu_data[me].ipi_pipe, 1, 1);
 179         if(err < 0)
 180                 panic("CPU#0 failed to create IPI pipe, errno = %d", -err);
 181
 182         activate_ipi(cpu_data[me].ipi_pipe[0],
 183                      current->thread.mode.tt.extern_pid);
 184
 185         for(cpu = 1; cpu < ncpus; cpu++){
 186                 printk("Booting processor %d...\n", cpu);
 187
 188                 idle = idle_thread(cpu);
 189
 190                 init_idle(idle, cpu);
 191                 unhash_process(idle);
 192
 193                 waittime = 200000000;
 194                 while (waittime-- && !cpu_isset(cpu, cpu_callin_map))
 195                         cpu_relax();
 196
 197                 if (cpu_isset(cpu, cpu_callin_map))
 198                         printk("done\n");
 199                 else printk("failed\n");
 200         }
 201 }
 202
 203 void smp_prepare_boot_cpu(void)
 204 {
 205         cpu_set(smp_processor_id(), cpu_online_map);
 206 }
 207
 208 int __cpu_up(unsigned int cpu)
 209 {
 210         cpu_set(cpu, smp_commenced_mask);
 211         while (!cpu_isset(cpu, cpu_online_map))
 212                 mb();
 213         return(0);
 214 }
 215
 216 int setup_profiling_timer(unsigned int multiplier)
 217 {
 218         printk(KERN_INFO "setup_profiling_timer\n");
 219         return(0);
 220 }
 221
 222 void smp_call_function_slave(int cpu);
 223
 224 void IPI_handler(int cpu)
 225 {
 226         unsigned char c;
 227         int fd;
 228
 229         fd = cpu_data[cpu].ipi_pipe[0];
 230         while (os_read_file(fd, &c, 1) == 1) {
 231                 switch (c) {
 232                 case 'C':
 233                         smp_call_function_slave(cpu);
 234                         break;
 235
 236                 case 'R':
 237                         set_tsk_need_resched(current);
 238                         break;
 239
 240                 case 'S':
 241                         printk("CPU#%d stopping\n", cpu);
 242                         while(1)
 243                                 pause();
 244                         break;
 245
 246                 default:
 247                         printk("CPU#%d received unknown IPI [%c]!\n", cpu, c);
 248                         break;
 249                 }
 250         }
 251 }
 252
 253 int hard_smp_processor_id(void)
 254 {
 255         return(pid_to_processor_id(os_getpid()));
 256 }
 257
 258 static spinlock_t call_lock = SPIN_LOCK_UNLOCKED;
 259 static atomic_t scf_started;
 260 static atomic_t scf_finished;
 261 static void (*func)(void *info);
 262 static void *info;
 263
 264 void smp_call_function_slave(int cpu)
 265 {
 266         atomic_inc(&scf_started);
 267         (*func)(info);
 268         atomic_inc(&scf_finished);
 269 }
 270
 271 int smp_call_function(void (*_func)(void *info), void *_info, int nonatomic,
 272                       int wait)
 273 {
 274         int cpus = num_online_cpus() - 1;
 275         int i;
 276
 277         if (!cpus)
 278                 return 0;
 279
 280         spin_lock_bh(&call_lock);
 281         atomic_set(&scf_started, 0);
 282         atomic_set(&scf_finished, 0);
 283         func = _func;
 284         info = _info;
 285
 286         for (i=0;i<NR_CPUS;i++)
 287                 if((i != current_thread->cpu) &&
 288                    cpu_isset(i, cpu_online_map))
 289                         os_write_file(cpu_data[i].ipi_pipe[1], "C", 1);
 290
 291         while (atomic_read(&scf_started) != cpus)
 292                 barrier();
 293
 294         if (wait)
 295                 while (atomic_read(&scf_finished) != cpus)
 296                         barrier();
 297
 298         spin_unlock_bh(&call_lock);
 299         return 0;
 300 }
 301
 302 #endif
 303
 304 /*
 305  * Overrides for Emacs so that we follow Linus's tabbing style.
 306  * Emacs will notice this stuff at the end of the file and automatically
 307  * adjust the settings for this buffer only.  This must remain at the end
 308  * of the file.
 309  * ---------------------------------------------------------------------------
 310  * Local variables:
 311  * c-file-style: "linux"
 312  * End:
 313  */