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/vdso_datapage.h>
  48 #ifdef CONFIG_PPC64
  49 #include <asm/paca.h>
  50 #endif
  51
  52 #ifdef DEBUG
  53 #include <asm/udbg.h>
  54 #define DBG(fmt...) udbg_printf(fmt)
  55 #else
  56 #define DBG(fmt...)
  57 #endif
  58
  59 int smp_hw_index[NR_CPUS];
  60 struct thread_info *secondary_ti;
  61
  62 cpumask_t cpu_possible_map = CPU_MASK_NONE;
  63 cpumask_t cpu_online_map = CPU_MASK_NONE;
  64 cpumask_t cpu_sibling_map[NR_CPUS] = { [0 ... NR_CPUS-1] = CPU_MASK_NONE };
  65
  66 EXPORT_SYMBOL(cpu_online_map);
  67 EXPORT_SYMBOL(cpu_possible_map);
  68
  69 /* SMP operations for this machine */
  70 struct smp_ops_t *smp_ops;
  71
  72 static volatile unsigned int cpu_callin_map[NR_CPUS];
  73
  74 void smp_call_function_interrupt(void);
  75
  76 int smt_enabled_at_boot = 1;
  77
  78 #ifdef CONFIG_MPIC
  79 int __init smp_mpic_probe(void)
  80 {
  81         int nr_cpus;
  82
  83         DBG("smp_mpic_probe()...\n");
  84
  85         nr_cpus = cpus_weight(cpu_possible_map);
  86
  87         DBG("nr_cpus: %d\n", nr_cpus);
  88
  89         if (nr_cpus > 1)
  90                 mpic_request_ipis();
  91
  92         return nr_cpus;
  93 }
  94
  95 void __devinit smp_mpic_setup_cpu(int cpu)
  96 {
  97         mpic_setup_this_cpu();
  98 }
  99 #endif /* CONFIG_MPIC */
 100
 101 #ifdef CONFIG_PPC64
 102 void __devinit smp_generic_kick_cpu(int nr)
 103 {
 104         BUG_ON(nr < 0 || nr >= NR_CPUS);
 105
 106         /*
 107          * The processor is currently spinning, waiting for the
 108          * cpu_start field to become non-zero After we set cpu_start,
 109          * the processor will continue on to secondary_start
 110          */
 111         paca[nr].cpu_start = 1;
 112         smp_mb();
 113 }
 114 #endif
 115
 116 void smp_message_recv(int msg, struct pt_regs *regs)
 117 {
 118         switch(msg) {
 119         case PPC_MSG_CALL_FUNCTION:
 120                 smp_call_function_interrupt();
 121                 break;
 122         case PPC_MSG_RESCHEDULE:
 123                 /* XXX Do we have to do this? */
 124                 set_need_resched();
 125                 break;
 126 #ifdef CONFIG_DEBUGGER
 127         case PPC_MSG_DEBUGGER_BREAK:
 128                 debugger_ipi(regs);
 129                 break;
 130 #endif
 131         default:
 132                 printk("SMP %d: smp_message_recv(): unknown msg %d\n",
 133                        smp_processor_id(), msg);
 134                 break;
 135         }
 136 }
 137
 138 void smp_send_reschedule(int cpu)
 139 {
 140         smp_ops->message_pass(cpu, PPC_MSG_RESCHEDULE);
 141 }
 142
 143 #ifdef CONFIG_DEBUGGER
 144 void smp_send_debugger_break(int cpu)
 145 {
 146         smp_ops->message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
 147 }
 148 #endif
 149
 150 static void stop_this_cpu(void *dummy)
 151 {
 152         local_irq_disable();
 153         while (1)
 154                 ;
 155 }
 156
 157 void smp_send_stop(void)
 158 {
 159         smp_call_function(stop_this_cpu, NULL, 1, 0);
 160 }
 161
 162 /*
 163  * Structure and data for smp_call_function(). This is designed to minimise
 164  * static memory requirements. It also looks cleaner.
 165  * Stolen from the i386 version.
 166  */
 167 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_lock);
 168
 169 static struct call_data_struct {
 170         void (*func) (void *info);
 171         void *info;
 172         atomic_t started;
 173         atomic_t finished;
 174         int wait;
 175 } *call_data;
 176
 177 /* delay of at least 8 seconds */
 178 #define SMP_CALL_TIMEOUT        8
 179
 180 /*
 181  * This function sends a 'generic call function' IPI to all other CPUs
 182  * in the system.
 183  *
 184  * [SUMMARY] Run a function on all other CPUs.
 185  * <func> The function to run. This must be fast and non-blocking.
 186  * <info> An arbitrary pointer to pass to the function.
 187  * <nonatomic> currently unused.
 188  * <wait> If true, wait (atomically) until function has completed on other CPUs.
 189  * [RETURNS] 0 on success, else a negative status code. Does not return until
 190  * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 191  *
 192  * You must not call this function with disabled interrupts or from a
 193  * hardware interrupt handler or from a bottom half handler.
 194  */
 195 int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
 196                        int wait)
 197 {
 198         struct call_data_struct data;
 199         int ret = -1, cpus;
 200         u64 timeout;
 201
 202         /* Can deadlock when called with interrupts disabled */
 203         WARN_ON(irqs_disabled());
 204
 205         data.func = func;
 206         data.info = info;
 207         atomic_set(&data.started, 0);
 208         data.wait = wait;
 209         if (wait)
 210                 atomic_set(&data.finished, 0);
 211
 212         spin_lock(&call_lock);
 213         /* Must grab online cpu count with preempt disabled, otherwise
 214          * it can change. */
 215         cpus = num_online_cpus() - 1;
 216         if (!cpus) {
 217                 ret = 0;
 218                 goto out;
 219         }
 220
 221         call_data = &data;
 222         smp_wmb();
 223         /* Send a message to all other CPUs and wait for them to respond */
 224         smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_CALL_FUNCTION);
 225
 226         timeout = get_tb() + (u64) SMP_CALL_TIMEOUT * tb_ticks_per_sec;
 227
 228         /* Wait for response */
 229         while (atomic_read(&data.started) != cpus) {
 230                 HMT_low();
 231                 if (get_tb() >= timeout) {
 232                         printk("smp_call_function on cpu %d: other cpus not "
 233                                "responding (%d)\n", smp_processor_id(),
 234                                atomic_read(&data.started));
 235                         debugger(NULL);
 236                         goto out;
 237                 }
 238         }
 239
 240         if (wait) {
 241                 while (atomic_read(&data.finished) != cpus) {
 242                         HMT_low();
 243                         if (get_tb() >= timeout) {
 244                                 printk("smp_call_function on cpu %d: other "
 245                                        "cpus not finishing (%d/%d)\n",
 246                                        smp_processor_id(),
 247                                        atomic_read(&data.finished),
 248                                        atomic_read(&data.started));
 249                                 debugger(NULL);
 250                                 goto out;
 251                         }
 252                 }
 253         }
 254
 255         ret = 0;
 256
 257  out:
 258         call_data = NULL;
 259         HMT_medium();
 260         spin_unlock(&call_lock);
 261         return ret;
 262 }
 263
 264 EXPORT_SYMBOL(smp_call_function);
 265
 266 void smp_call_function_interrupt(void)
 267 {
 268         void (*func) (void *info);
 269         void *info;
 270         int wait;
 271
 272         /* call_data will be NULL if the sender timed out while
 273          * waiting on us to receive the call.
 274          */
 275         if (!call_data)
 276                 return;
 277
 278         func = call_data->func;
 279         info = call_data->info;
 280         wait = call_data->wait;
 281
 282         if (!wait)
 283                 smp_mb__before_atomic_inc();
 284
 285         /*
 286          * Notify initiating CPU that I've grabbed the data and am
 287          * about to execute the function
 288          */
 289         atomic_inc(&call_data->started);
 290         /*
 291          * At this point the info structure may be out of scope unless wait==1
 292          */
 293         (*func)(info);
 294         if (wait) {
 295                 smp_mb__before_atomic_inc();
 296                 atomic_inc(&call_data->finished);
 297         }
 298 }
 299
 300 extern struct gettimeofday_struct do_gtod;
 301
 302 struct thread_info *current_set[NR_CPUS];
 303
 304 DECLARE_PER_CPU(unsigned int, pvr);
 305
 306 static void __devinit smp_store_cpu_info(int id)
 307 {
 308         per_cpu(pvr, id) = mfspr(SPRN_PVR);
 309 }
 310
 311 static void __init smp_create_idle(unsigned int cpu)
 312 {
 313         struct task_struct *p;
 314
 315         /* create a process for the processor */
 316         p = fork_idle(cpu);
 317         if (IS_ERR(p))
 318                 panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
 319 #ifdef CONFIG_PPC64
 320         paca[cpu].__current = p;
 321 #endif
 322         current_set[cpu] = p->thread_info;
 323         p->thread_info->cpu = cpu;
 324 }
 325
 326 void __init smp_prepare_cpus(unsigned int max_cpus)
 327 {
 328         unsigned int cpu;
 329
 330         DBG("smp_prepare_cpus\n");
 331
 332         /*
 333          * setup_cpu may need to be called on the boot cpu. We havent
 334          * spun any cpus up but lets be paranoid.
 335          */
 336         BUG_ON(boot_cpuid != smp_processor_id());
 337
 338         /* Fixup boot cpu */
 339         smp_store_cpu_info(boot_cpuid);
 340         cpu_callin_map[boot_cpuid] = 1;
 341
 342         max_cpus = smp_ops->probe();
 343
 344         smp_space_timers(max_cpus);
 345
 346         for_each_cpu(cpu)
 347                 if (cpu != boot_cpuid)
 348                         smp_create_idle(cpu);
 349 }
 350
 351 void __devinit smp_prepare_boot_cpu(void)
 352 {
 353         BUG_ON(smp_processor_id() != boot_cpuid);
 354
 355         cpu_set(boot_cpuid, cpu_online_map);
 356 #ifdef CONFIG_PPC64
 357         paca[boot_cpuid].__current = current;
 358 #endif
 359         current_set[boot_cpuid] = current->thread_info;
 360 }
 361
 362 #ifdef CONFIG_HOTPLUG_CPU
 363 /* State of each CPU during hotplug phases */
 364 DEFINE_PER_CPU(int, cpu_state) = { 0 };
 365
 366 int generic_cpu_disable(void)
 367 {
 368         unsigned int cpu = smp_processor_id();
 369
 370         if (cpu == boot_cpuid)
 371                 return -EBUSY;
 372
 373         cpu_clear(cpu, cpu_online_map);
 374 #ifdef CONFIG_PPC64
 375         vdso_data->processorCount--;
 376         fixup_irqs(cpu_online_map);
 377 #endif
 378         return 0;
 379 }
 380
 381 int generic_cpu_enable(unsigned int cpu)
 382 {
 383         /* Do the normal bootup if we haven't
 384          * already bootstrapped. */
 385         if (system_state != SYSTEM_RUNNING)
 386                 return -ENOSYS;
 387
 388         /* get the target out of it's holding state */
 389         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 390         smp_wmb();
 391
 392         while (!cpu_online(cpu))
 393                 cpu_relax();
 394
 395 #ifdef CONFIG_PPC64
 396         fixup_irqs(cpu_online_map);
 397         /* counter the irq disable in fixup_irqs */
 398         local_irq_enable();
 399 #endif
 400         return 0;
 401 }
 402
 403 void generic_cpu_die(unsigned int cpu)
 404 {
 405         int i;
 406
 407         for (i = 0; i < 100; i++) {
 408                 smp_rmb();
 409                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
 410                         return;
 411                 msleep(100);
 412         }
 413         printk(KERN_ERR "CPU%d didn't die...\n", cpu);
 414 }
 415
 416 void generic_mach_cpu_die(void)
 417 {
 418         unsigned int cpu;
 419
 420         local_irq_disable();
 421         cpu = smp_processor_id();
 422         printk(KERN_DEBUG "CPU%d offline\n", cpu);
 423         __get_cpu_var(cpu_state) = CPU_DEAD;
 424         smp_wmb();
 425         while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 426                 cpu_relax();
 427
 428 #ifdef CONFIG_PPC64
 429         flush_tlb_pending();
 430 #endif
 431         cpu_set(cpu, cpu_online_map);
 432         local_irq_enable();
 433 }
 434 #endif
 435
 436 static int __devinit cpu_enable(unsigned int cpu)
 437 {
 438         if (smp_ops->cpu_enable)
 439                 return smp_ops->cpu_enable(cpu);
 440
 441         return -ENOSYS;
 442 }
 443
 444 int __devinit __cpu_up(unsigned int cpu)
 445 {
 446         int c;
 447
 448         secondary_ti = current_set[cpu];
 449         if (!cpu_enable(cpu))
 450                 return 0;
 451
 452         if (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu))
 453                 return -EINVAL;
 454
 455 #ifdef CONFIG_PPC64
 456         paca[cpu].default_decr = tb_ticks_per_jiffy;
 457 #endif
 458
 459         /* Make sure callin-map entry is 0 (can be leftover a CPU
 460          * hotplug
 461          */
 462         cpu_callin_map[cpu] = 0;
 463
 464         /* The information for processor bringup must
 465          * be written out to main store before we release
 466          * the processor.
 467          */
 468         smp_mb();
 469
 470         /* wake up cpus */
 471         DBG("smp: kicking cpu %d\n", cpu);
 472         smp_ops->kick_cpu(cpu);
 473
 474         /*
 475          * wait to see if the cpu made a callin (is actually up).
 476          * use this value that I found through experimentation.
 477          * -- Cort
 478          */
 479         if (system_state < SYSTEM_RUNNING)
 480                 for (c = 5000; c && !cpu_callin_map[cpu]; c--)
 481                         udelay(100);
 482 #ifdef CONFIG_HOTPLUG_CPU
 483         else
 484                 /*
 485                  * CPUs can take much longer to come up in the
 486                  * hotplug case.  Wait five seconds.
 487                  */
 488                 for (c = 25; c && !cpu_callin_map[cpu]; c--) {
 489                         msleep(200);
 490                 }
 491 #endif
 492
 493         if (!cpu_callin_map[cpu]) {
 494                 printk("Processor %u is stuck.\n", cpu);
 495                 return -ENOENT;
 496         }
 497
 498         printk("Processor %u found.\n", cpu);
 499
 500         if (smp_ops->give_timebase)
 501                 smp_ops->give_timebase();
 502
 503         /* Wait until cpu puts itself in the online map */
 504         while (!cpu_online(cpu))
 505                 cpu_relax();
 506
 507         return 0;
 508 }
 509
 510
 511 /* Activate a secondary processor. */
 512 int __devinit start_secondary(void *unused)
 513 {
 514         unsigned int cpu = smp_processor_id();
 515
 516         atomic_inc(&init_mm.mm_count);
 517         current->active_mm = &init_mm;
 518
 519         smp_store_cpu_info(cpu);
 520         set_dec(tb_ticks_per_jiffy);
 521         preempt_disable();
 522         cpu_callin_map[cpu] = 1;
 523
 524         smp_ops->setup_cpu(cpu);
 525         if (smp_ops->take_timebase)
 526                 smp_ops->take_timebase();
 527
 528         spin_lock(&call_lock);
 529         cpu_set(cpu, cpu_online_map);
 530         spin_unlock(&call_lock);
 531
 532         local_irq_enable();
 533
 534         cpu_idle();
 535         return 0;
 536 }
 537
 538 int setup_profiling_timer(unsigned int multiplier)
 539 {
 540         return 0;
 541 }
 542
 543 void __init smp_cpus_done(unsigned int max_cpus)
 544 {
 545         cpumask_t old_mask;
 546
 547         /* We want the setup_cpu() here to be called from CPU 0, but our
 548          * init thread may have been "borrowed" by another CPU in the meantime
 549          * se we pin us down to CPU 0 for a short while
 550          */
 551         old_mask = current->cpus_allowed;
 552         set_cpus_allowed(current, cpumask_of_cpu(boot_cpuid));
 553
 554         smp_ops->setup_cpu(boot_cpuid);
 555
 556         set_cpus_allowed(current, old_mask);
 557 }
 558
 559 #ifdef CONFIG_HOTPLUG_CPU
 560 int __cpu_disable(void)
 561 {
 562         if (smp_ops->cpu_disable)
 563                 return smp_ops->cpu_disable();
 564
 565         return -ENOSYS;
 566 }
 567
 568 void __cpu_die(unsigned int cpu)
 569 {
 570         if (smp_ops->cpu_die)
 571                 smp_ops->cpu_die(cpu);
 572 }
 573 #endif