arch/powerpc/kernel/smp.c

   1 /*
   2  * SMP support for ppc.
   3  *
   4  * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great
   5  * deal of code from the sparc and intel versions.
   6  *
   7  * Copyright (C) 1999 Cort Dougan <cort@cs.nmt.edu>
   8  *
   9  * PowerPC-64 Support added by Dave Engebretsen, Peter Bergner, and
  10  * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
  11  *
  12  *      This program is free software; you can redistribute it and/or
  13  *      modify it under the terms of the GNU General Public License
  14  *      as published by the Free Software Foundation; either version
  15  *      2 of the License, or (at your option) any later version.
  16  */
  17
  18 #undef DEBUG
  19
  20 #include <linux/config.h>
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/sched.h>
  24 #include <linux/smp.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/delay.h>
  27 #include <linux/init.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/cache.h>
  30 #include <linux/err.h>
  31 #include <linux/sysdev.h>
  32 #include <linux/cpu.h>
  33 #include <linux/notifier.h>
  34
  35 #include <asm/ptrace.h>
  36 #include <asm/atomic.h>
  37 #include <asm/irq.h>
  38 #include <asm/page.h>
  39 #include <asm/pgtable.h>
  40 #include <asm/prom.h>
  41 #include <asm/smp.h>
  42 #include <asm/time.h>
  43 #include <asm/machdep.h>
  44 #include <asm/cputable.h>
  45 #include <asm/system.h>
  46 #include <asm/mpic.h>
  47 #include <asm/systemcfg.h>
  48 #ifdef CONFIG_PPC64
  49 #include <asm/paca.h>
  50 #endif
  51
  52 int smp_hw_index[NR_CPUS];
  53 struct thread_info *secondary_ti;
  54
  55 #ifdef DEBUG
  56 #define DBG(fmt...) udbg_printf(fmt)
  57 #else
  58 #define DBG(fmt...)
  59 #endif
  60
  61 cpumask_t cpu_possible_map = CPU_MASK_NONE;
  62 cpumask_t cpu_online_map = CPU_MASK_NONE;
  63 cpumask_t cpu_sibling_map[NR_CPUS] = { [0 ... NR_CPUS-1] = CPU_MASK_NONE };
  64
  65 EXPORT_SYMBOL(cpu_online_map);
  66 EXPORT_SYMBOL(cpu_possible_map);
  67
  68 /* SMP operations for this machine */
  69 struct smp_ops_t *smp_ops;
  70
  71 static volatile unsigned int cpu_callin_map[NR_CPUS];
  72
  73 void smp_call_function_interrupt(void);
  74
  75 int smt_enabled_at_boot = 1;
  76
  77 #ifdef CONFIG_MPIC
  78 int __init smp_mpic_probe(void)
  79 {
  80         int nr_cpus;
  81
  82         DBG("smp_mpic_probe()...\n");
  83
  84         nr_cpus = cpus_weight(cpu_possible_map);
  85
  86         DBG("nr_cpus: %d\n", nr_cpus);
  87
  88         if (nr_cpus > 1)
  89                 mpic_request_ipis();
  90
  91         return nr_cpus;
  92 }
  93
  94 void __devinit smp_mpic_setup_cpu(int cpu)
  95 {
  96         mpic_setup_this_cpu();
  97 }
  98 #endif /* CONFIG_MPIC */
  99
 100 #ifdef CONFIG_PPC64
 101 void __devinit smp_generic_kick_cpu(int nr)
 102 {
 103         BUG_ON(nr < 0 || nr >= NR_CPUS);
 104
 105         /*
 106          * The processor is currently spinning, waiting for the
 107          * cpu_start field to become non-zero After we set cpu_start,
 108          * the processor will continue on to secondary_start
 109          */
 110         paca[nr].cpu_start = 1;
 111         smp_mb();
 112 }
 113 #endif
 114
 115 void smp_message_recv(int msg, struct pt_regs *regs)
 116 {
 117         switch(msg) {
 118         case PPC_MSG_CALL_FUNCTION:
 119                 smp_call_function_interrupt();
 120                 break;
 121         case PPC_MSG_RESCHEDULE:
 122                 /* XXX Do we have to do this? */
 123                 set_need_resched();
 124                 break;
 125 #ifdef CONFIG_DEBUGGER
 126         case PPC_MSG_DEBUGGER_BREAK:
 127                 debugger_ipi(regs);
 128                 break;
 129 #endif
 130         default:
 131                 printk("SMP %d: smp_message_recv(): unknown msg %d\n",
 132                        smp_processor_id(), msg);
 133                 break;
 134         }
 135 }
 136
 137 void smp_send_reschedule(int cpu)
 138 {
 139         smp_ops->message_pass(cpu, PPC_MSG_RESCHEDULE);
 140 }
 141
 142 #ifdef CONFIG_DEBUGGER
 143 void smp_send_debugger_break(int cpu)
 144 {
 145         smp_ops->message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
 146 }
 147 #endif
 148
 149 static void stop_this_cpu(void *dummy)
 150 {
 151         local_irq_disable();
 152         while (1)
 153                 ;
 154 }
 155
 156 void smp_send_stop(void)
 157 {
 158         smp_call_function(stop_this_cpu, NULL, 1, 0);
 159 }
 160
 161 /*
 162  * Structure and data for smp_call_function(). This is designed to minimise
 163  * static memory requirements. It also looks cleaner.
 164  * Stolen from the i386 version.
 165  */
 166 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_lock);
 167
 168 static struct call_data_struct {
 169         void (*func) (void *info);
 170         void *info;
 171         atomic_t started;
 172         atomic_t finished;
 173         int wait;
 174 } *call_data;
 175
 176 /* delay of at least 8 seconds */
 177 #define SMP_CALL_TIMEOUT        8
 178
 179 /*
 180  * This function sends a 'generic call function' IPI to all other CPUs
 181  * in the system.
 182  *
 183  * [SUMMARY] Run a function on all other CPUs.
 184  * <func> The function to run. This must be fast and non-blocking.
 185  * <info> An arbitrary pointer to pass to the function.
 186  * <nonatomic> currently unused.
 187  * <wait> If true, wait (atomically) until function has completed on other CPUs.
 188  * [RETURNS] 0 on success, else a negative status code. Does not return until
 189  * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 190  *
 191  * You must not call this function with disabled interrupts or from a
 192  * hardware interrupt handler or from a bottom half handler.
 193  */
 194 int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
 195                        int wait)
 196 {
 197         struct call_data_struct data;
 198         int ret = -1, cpus;
 199         u64 timeout;
 200
 201         /* Can deadlock when called with interrupts disabled */
 202         WARN_ON(irqs_disabled());
 203
 204         data.func = func;
 205         data.info = info;
 206         atomic_set(&data.started, 0);
 207         data.wait = wait;
 208         if (wait)
 209                 atomic_set(&data.finished, 0);
 210
 211         spin_lock(&call_lock);
 212         /* Must grab online cpu count with preempt disabled, otherwise
 213          * it can change. */
 214         cpus = num_online_cpus() - 1;
 215         if (!cpus) {
 216                 ret = 0;
 217                 goto out;
 218         }
 219
 220         call_data = &data;
 221         smp_wmb();
 222         /* Send a message to all other CPUs and wait for them to respond */
 223         smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_CALL_FUNCTION);
 224
 225         timeout = get_tb() + (u64) SMP_CALL_TIMEOUT * tb_ticks_per_sec;
 226
 227         /* Wait for response */
 228         while (atomic_read(&data.started) != cpus) {
 229                 HMT_low();
 230                 if (get_tb() >= timeout) {
 231                         printk("smp_call_function on cpu %d: other cpus not "
 232                                "responding (%d)\n", smp_processor_id(),
 233                                atomic_read(&data.started));
 234                         debugger(NULL);
 235                         goto out;
 236                 }
 237         }
 238
 239         if (wait) {
 240                 while (atomic_read(&data.finished) != cpus) {
 241                         HMT_low();
 242                         if (get_tb() >= timeout) {
 243                                 printk("smp_call_function on cpu %d: other "
 244                                        "cpus not finishing (%d/%d)\n",
 245                                        smp_processor_id(),
 246                                        atomic_read(&data.finished),
 247                                        atomic_read(&data.started));
 248                                 debugger(NULL);
 249                                 goto out;
 250                         }
 251                 }
 252         }
 253
 254         ret = 0;
 255
 256  out:
 257         call_data = NULL;
 258         HMT_medium();
 259         spin_unlock(&call_lock);
 260         return ret;
 261 }
 262
 263 EXPORT_SYMBOL(smp_call_function);
 264
 265 void smp_call_function_interrupt(void)
 266 {
 267         void (*func) (void *info);
 268         void *info;
 269         int wait;
 270
 271         /* call_data will be NULL if the sender timed out while
 272          * waiting on us to receive the call.
 273          */
 274         if (!call_data)
 275                 return;
 276
 277         func = call_data->func;
 278         info = call_data->info;
 279         wait = call_data->wait;
 280
 281         if (!wait)
 282                 smp_mb__before_atomic_inc();
 283
 284         /*
 285          * Notify initiating CPU that I've grabbed the data and am
 286          * about to execute the function
 287          */
 288         atomic_inc(&call_data->started);
 289         /*
 290          * At this point the info structure may be out of scope unless wait==1
 291          */
 292         (*func)(info);
 293         if (wait) {
 294                 smp_mb__before_atomic_inc();
 295                 atomic_inc(&call_data->finished);
 296         }
 297 }
 298
 299 extern struct gettimeofday_struct do_gtod;
 300
 301 struct thread_info *current_set[NR_CPUS];
 302
 303 DECLARE_PER_CPU(unsigned int, pvr);
 304
 305 static void __devinit smp_store_cpu_info(int id)
 306 {
 307         per_cpu(pvr, id) = mfspr(SPRN_PVR);
 308 }
 309
 310 static void __init smp_create_idle(unsigned int cpu)
 311 {
 312         struct task_struct *p;
 313
 314         /* create a process for the processor */
 315         p = fork_idle(cpu);
 316         if (IS_ERR(p))
 317                 panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
 318 #ifdef CONFIG_PPC64
 319         paca[cpu].__current = p;
 320 #endif
 321         current_set[cpu] = p->thread_info;
 322         p->thread_info->cpu = cpu;
 323 }
 324
 325 void __init smp_prepare_cpus(unsigned int max_cpus)
 326 {
 327         unsigned int cpu;
 328
 329         DBG("smp_prepare_cpus\n");
 330
 331         /*
 332          * setup_cpu may need to be called on the boot cpu. We havent
 333          * spun any cpus up but lets be paranoid.
 334          */
 335         BUG_ON(boot_cpuid != smp_processor_id());
 336
 337         /* Fixup boot cpu */
 338         smp_store_cpu_info(boot_cpuid);
 339         cpu_callin_map[boot_cpuid] = 1;
 340
 341         max_cpus = smp_ops->probe();
 342
 343         smp_space_timers(max_cpus);
 344
 345         for_each_cpu(cpu)
 346                 if (cpu != boot_cpuid)
 347                         smp_create_idle(cpu);
 348 }
 349
 350 void __devinit smp_prepare_boot_cpu(void)
 351 {
 352         BUG_ON(smp_processor_id() != boot_cpuid);
 353
 354         cpu_set(boot_cpuid, cpu_online_map);
 355 #ifdef CONFIG_PPC64
 356         paca[boot_cpuid].__current = current;
 357 #endif
 358         current_set[boot_cpuid] = current->thread_info;
 359 }
 360
 361 #ifdef CONFIG_HOTPLUG_CPU
 362 /* State of each CPU during hotplug phases */
 363 DEFINE_PER_CPU(int, cpu_state) = { 0 };
 364
 365 int generic_cpu_disable(void)
 366 {
 367         unsigned int cpu = smp_processor_id();
 368
 369         if (cpu == boot_cpuid)
 370                 return -EBUSY;
 371
 372 #ifdef CONFIG_PPC64
 373         _systemcfg->processorCount--;
 374 #endif
 375         cpu_clear(cpu, cpu_online_map);
 376         fixup_irqs(cpu_online_map);
 377         return 0;
 378 }
 379
 380 int generic_cpu_enable(unsigned int cpu)
 381 {
 382         /* Do the normal bootup if we haven't
 383          * already bootstrapped. */
 384         if (system_state != SYSTEM_RUNNING)
 385                 return -ENOSYS;
 386
 387         /* get the target out of it's holding state */
 388         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 389         smp_wmb();
 390
 391         while (!cpu_online(cpu))
 392                 cpu_relax();
 393
 394         fixup_irqs(cpu_online_map);
 395         /* counter the irq disable in fixup_irqs */
 396         local_irq_enable();
 397         return 0;
 398 }
 399
 400 void generic_cpu_die(unsigned int cpu)
 401 {
 402         int i;
 403
 404         for (i = 0; i < 100; i++) {
 405                 smp_rmb();
 406                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
 407                         return;
 408                 msleep(100);
 409         }
 410         printk(KERN_ERR "CPU%d didn't die...\n", cpu);
 411 }
 412
 413 void generic_mach_cpu_die(void)
 414 {
 415         unsigned int cpu;
 416
 417         local_irq_disable();
 418         cpu = smp_processor_id();
 419         printk(KERN_DEBUG "CPU%d offline\n", cpu);
 420         __get_cpu_var(cpu_state) = CPU_DEAD;
 421         smp_wmb();
 422         while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 423                 cpu_relax();
 424
 425         flush_tlb_pending();
 426         cpu_set(cpu, cpu_online_map);
 427         local_irq_enable();
 428 }
 429 #endif
 430
 431 static int __devinit cpu_enable(unsigned int cpu)
 432 {
 433         if (smp_ops->cpu_enable)
 434                 return smp_ops->cpu_enable(cpu);
 435
 436         return -ENOSYS;
 437 }
 438
 439 int __devinit __cpu_up(unsigned int cpu)
 440 {
 441         int c;
 442
 443         secondary_ti = current_set[cpu];
 444         if (!cpu_enable(cpu))
 445                 return 0;
 446
 447         if (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu))
 448                 return -EINVAL;
 449
 450 #ifdef CONFIG_PPC64
 451         paca[cpu].default_decr = tb_ticks_per_jiffy;
 452 #endif
 453
 454         /* Make sure callin-map entry is 0 (can be leftover a CPU
 455          * hotplug
 456          */
 457         cpu_callin_map[cpu] = 0;
 458
 459         /* The information for processor bringup must
 460          * be written out to main store before we release
 461          * the processor.
 462          */
 463         smp_mb();
 464
 465         /* wake up cpus */
 466         DBG("smp: kicking cpu %d\n", cpu);
 467         smp_ops->kick_cpu(cpu);
 468
 469         /*
 470          * wait to see if the cpu made a callin (is actually up).
 471          * use this value that I found through experimentation.
 472          * -- Cort
 473          */
 474         if (system_state < SYSTEM_RUNNING)
 475                 for (c = 5000; c && !cpu_callin_map[cpu]; c--)
 476                         udelay(100);
 477 #ifdef CONFIG_HOTPLUG_CPU
 478         else
 479                 /*
 480                  * CPUs can take much longer to come up in the
 481                  * hotplug case.  Wait five seconds.
 482                  */
 483                 for (c = 25; c && !cpu_callin_map[cpu]; c--) {
 484                         msleep(200);
 485                 }
 486 #endif
 487
 488         if (!cpu_callin_map[cpu]) {
 489                 printk("Processor %u is stuck.\n", cpu);
 490                 return -ENOENT;
 491         }
 492
 493         printk("Processor %u found.\n", cpu);
 494
 495         if (smp_ops->give_timebase)
 496                 smp_ops->give_timebase();
 497
 498         /* Wait until cpu puts itself in the online map */
 499         while (!cpu_online(cpu))
 500                 cpu_relax();
 501
 502         return 0;
 503 }
 504
 505
 506 /* Activate a secondary processor. */
 507 int __devinit start_secondary(void *unused)
 508 {
 509         unsigned int cpu = smp_processor_id();
 510
 511         atomic_inc(&init_mm.mm_count);
 512         current->active_mm = &init_mm;
 513
 514         smp_store_cpu_info(cpu);
 515         set_dec(tb_ticks_per_jiffy);
 516         cpu_callin_map[cpu] = 1;
 517
 518         smp_ops->setup_cpu(cpu);
 519         if (smp_ops->take_timebase)
 520                 smp_ops->take_timebase();
 521
 522         spin_lock(&call_lock);
 523         cpu_set(cpu, cpu_online_map);
 524         spin_unlock(&call_lock);
 525
 526         local_irq_enable();
 527
 528         cpu_idle();
 529         return 0;
 530 }
 531
 532 int setup_profiling_timer(unsigned int multiplier)
 533 {
 534         return 0;
 535 }
 536
 537 void __init smp_cpus_done(unsigned int max_cpus)
 538 {
 539         cpumask_t old_mask;
 540
 541         /* We want the setup_cpu() here to be called from CPU 0, but our
 542          * init thread may have been "borrowed" by another CPU in the meantime
 543          * se we pin us down to CPU 0 for a short while
 544          */
 545         old_mask = current->cpus_allowed;
 546         set_cpus_allowed(current, cpumask_of_cpu(boot_cpuid));
 547
 548         smp_ops->setup_cpu(boot_cpuid);
 549
 550         set_cpus_allowed(current, old_mask);
 551 }
 552
 553 #ifdef CONFIG_HOTPLUG_CPU
 554 int __cpu_disable(void)
 555 {
 556         if (smp_ops->cpu_disable)
 557                 return smp_ops->cpu_disable();
 558
 559         return -ENOSYS;
 560 }
 561
 562 void __cpu_die(unsigned int cpu)
 563 {
 564         if (smp_ops->cpu_die)
 565                 smp_ops->cpu_die(cpu);
 566 }
 567 #endif