arch/ppc64/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/paca.h>
  43 #include <asm/time.h>
  44 #include <asm/machdep.h>
  45 #include <asm/cputable.h>
  46 #include <asm/system.h>
  47 #include <asm/abs_addr.h>
  48
  49 #include "mpic.h"
  50
  51 #ifdef DEBUG
  52 #define DBG(fmt...) udbg_printf(fmt)
  53 #else
  54 #define DBG(fmt...)
  55 #endif
  56
  57 cpumask_t cpu_possible_map = CPU_MASK_NONE;
  58 cpumask_t cpu_online_map = CPU_MASK_NONE;
  59 cpumask_t cpu_sibling_map[NR_CPUS] = { [0 ... NR_CPUS-1] = CPU_MASK_NONE };
  60
  61 EXPORT_SYMBOL(cpu_online_map);
  62 EXPORT_SYMBOL(cpu_possible_map);
  63
  64 struct smp_ops_t *smp_ops;
  65
  66 static volatile unsigned int cpu_callin_map[NR_CPUS];
  67
  68 void smp_call_function_interrupt(void);
  69
  70 int smt_enabled_at_boot = 1;
  71
  72 #ifdef CONFIG_MPIC
  73 void smp_mpic_message_pass(int target, int msg)
  74 {
  75         /* make sure we're sending something that translates to an IPI */
  76         if ( msg > 0x3 ){
  77                 printk("SMP %d: smp_message_pass: unknown msg %d\n",
  78                        smp_processor_id(), msg);
  79                 return;
  80         }
  81         switch ( target )
  82         {
  83         case MSG_ALL:
  84                 mpic_send_ipi(msg, 0xffffffff);
  85                 break;
  86         case MSG_ALL_BUT_SELF:
  87                 mpic_send_ipi(msg, 0xffffffff & ~(1 << smp_processor_id()));
  88                 break;
  89         default:
  90                 mpic_send_ipi(msg, 1 << target);
  91                 break;
  92         }
  93 }
  94
  95 int __init smp_mpic_probe(void)
  96 {
  97         int nr_cpus;
  98
  99         DBG("smp_mpic_probe()...\n");
 100
 101         nr_cpus = cpus_weight(cpu_possible_map);
 102
 103         DBG("nr_cpus: %d\n", nr_cpus);
 104
 105         if (nr_cpus > 1)
 106                 mpic_request_ipis();
 107
 108         return nr_cpus;
 109 }
 110
 111 void __devinit smp_mpic_setup_cpu(int cpu)
 112 {
 113         mpic_setup_this_cpu();
 114 }
 115
 116 void __devinit smp_generic_kick_cpu(int nr)
 117 {
 118         BUG_ON(nr < 0 || nr >= NR_CPUS);
 119
 120         /*
 121          * The processor is currently spinning, waiting for the
 122          * cpu_start field to become non-zero After we set cpu_start,
 123          * the processor will continue on to secondary_start
 124          */
 125         paca[nr].cpu_start = 1;
 126         smp_mb();
 127 }
 128
 129 #endif /* CONFIG_MPIC */
 130
 131 static void __init smp_space_timers(unsigned int max_cpus)
 132 {
 133         int i;
 134         unsigned long offset = tb_ticks_per_jiffy / max_cpus;
 135         unsigned long previous_tb = paca[boot_cpuid].next_jiffy_update_tb;
 136
 137         for_each_cpu(i) {
 138                 if (i != boot_cpuid) {
 139                         paca[i].next_jiffy_update_tb =
 140                                 previous_tb + offset;
 141                         previous_tb = paca[i].next_jiffy_update_tb;
 142                 }
 143         }
 144 }
 145
 146 void smp_message_recv(int msg, struct pt_regs *regs)
 147 {
 148         switch(msg) {
 149         case PPC_MSG_CALL_FUNCTION:
 150                 smp_call_function_interrupt();
 151                 break;
 152         case PPC_MSG_RESCHEDULE:
 153                 /* XXX Do we have to do this? */
 154                 set_need_resched();
 155                 break;
 156 #if 0
 157         case PPC_MSG_MIGRATE_TASK:
 158                 /* spare */
 159                 break;
 160 #endif
 161 #ifdef CONFIG_DEBUGGER
 162         case PPC_MSG_DEBUGGER_BREAK:
 163                 debugger_ipi(regs);
 164                 break;
 165 #endif
 166         default:
 167                 printk("SMP %d: smp_message_recv(): unknown msg %d\n",
 168                        smp_processor_id(), msg);
 169                 break;
 170         }
 171 }
 172
 173 void smp_send_reschedule(int cpu)
 174 {
 175         smp_ops->message_pass(cpu, PPC_MSG_RESCHEDULE);
 176 }
 177
 178 #ifdef CONFIG_DEBUGGER
 179 void smp_send_debugger_break(int cpu)
 180 {
 181         smp_ops->message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
 182 }
 183 #endif
 184
 185 static void stop_this_cpu(void *dummy)
 186 {
 187         local_irq_disable();
 188         while (1)
 189                 ;
 190 }
 191
 192 void smp_send_stop(void)
 193 {
 194         smp_call_function(stop_this_cpu, NULL, 1, 0);
 195 }
 196
 197 /*
 198  * Structure and data for smp_call_function(). This is designed to minimise
 199  * static memory requirements. It also looks cleaner.
 200  * Stolen from the i386 version.
 201  */
 202 static  __cacheline_aligned_in_smp DEFINE_SPINLOCK(call_lock);
 203
 204 static struct call_data_struct {
 205         void (*func) (void *info);
 206         void *info;
 207         atomic_t started;
 208         atomic_t finished;
 209         int wait;
 210 } *call_data;
 211
 212 /* delay of at least 8 seconds on 1GHz cpu */
 213 #define SMP_CALL_TIMEOUT (1UL << (30 + 3))
 214
 215 /*
 216  * This function sends a 'generic call function' IPI to all other CPUs
 217  * in the system.
 218  *
 219  * [SUMMARY] Run a function on all other CPUs.
 220  * <func> The function to run. This must be fast and non-blocking.
 221  * <info> An arbitrary pointer to pass to the function.
 222  * <nonatomic> currently unused.
 223  * <wait> If true, wait (atomically) until function has completed on other CPUs.
 224  * [RETURNS] 0 on success, else a negative status code. Does not return until
 225  * remote CPUs are nearly ready to execute <<func>> or are or have executed.
 226  *
 227  * You must not call this function with disabled interrupts or from a
 228  * hardware interrupt handler or from a bottom half handler.
 229  */
 230 int smp_call_function (void (*func) (void *info), void *info, int nonatomic,
 231                        int wait)
 232 {
 233         struct call_data_struct data;
 234         int ret = -1, cpus;
 235         unsigned long timeout;
 236
 237         /* Can deadlock when called with interrupts disabled */
 238         WARN_ON(irqs_disabled());
 239
 240         data.func = func;
 241         data.info = info;
 242         atomic_set(&data.started, 0);
 243         data.wait = wait;
 244         if (wait)
 245                 atomic_set(&data.finished, 0);
 246
 247         spin_lock(&call_lock);
 248         /* Must grab online cpu count with preempt disabled, otherwise
 249          * it can change. */
 250         cpus = num_online_cpus() - 1;
 251         if (!cpus) {
 252                 ret = 0;
 253                 goto out;
 254         }
 255
 256         call_data = &data;
 257         smp_wmb();
 258         /* Send a message to all other CPUs and wait for them to respond */
 259         smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_CALL_FUNCTION);
 260
 261         /* Wait for response */
 262         timeout = SMP_CALL_TIMEOUT;
 263         while (atomic_read(&data.started) != cpus) {
 264                 HMT_low();
 265                 if (--timeout == 0) {
 266                         printk("smp_call_function on cpu %d: other cpus not "
 267                                "responding (%d)\n", smp_processor_id(),
 268                                atomic_read(&data.started));
 269                         debugger(NULL);
 270                         goto out;
 271                 }
 272         }
 273
 274         if (wait) {
 275                 timeout = SMP_CALL_TIMEOUT;
 276                 while (atomic_read(&data.finished) != cpus) {
 277                         HMT_low();
 278                         if (--timeout == 0) {
 279                                 printk("smp_call_function on cpu %d: other "
 280                                        "cpus not finishing (%d/%d)\n",
 281                                        smp_processor_id(),
 282                                        atomic_read(&data.finished),
 283                                        atomic_read(&data.started));
 284                                 debugger(NULL);
 285                                 goto out;
 286                         }
 287                 }
 288         }
 289
 290         ret = 0;
 291
 292 out:
 293         call_data = NULL;
 294         HMT_medium();
 295         spin_unlock(&call_lock);
 296         return ret;
 297 }
 298
 299 EXPORT_SYMBOL(smp_call_function);
 300
 301 void smp_call_function_interrupt(void)
 302 {
 303         void (*func) (void *info);
 304         void *info;
 305         int wait;
 306
 307         /* call_data will be NULL if the sender timed out while
 308          * waiting on us to receive the call.
 309          */
 310         if (!call_data)
 311                 return;
 312
 313         func = call_data->func;
 314         info = call_data->info;
 315         wait = call_data->wait;
 316
 317         if (!wait)
 318                 smp_mb__before_atomic_inc();
 319
 320         /*
 321          * Notify initiating CPU that I've grabbed the data and am
 322          * about to execute the function
 323          */
 324         atomic_inc(&call_data->started);
 325         /*
 326          * At this point the info structure may be out of scope unless wait==1
 327          */
 328         (*func)(info);
 329         if (wait) {
 330                 smp_mb__before_atomic_inc();
 331                 atomic_inc(&call_data->finished);
 332         }
 333 }
 334
 335 extern struct gettimeofday_struct do_gtod;
 336
 337 struct thread_info *current_set[NR_CPUS];
 338
 339 DECLARE_PER_CPU(unsigned int, pvr);
 340
 341 static void __devinit smp_store_cpu_info(int id)
 342 {
 343         per_cpu(pvr, id) = mfspr(SPRN_PVR);
 344 }
 345
 346 static void __init smp_create_idle(unsigned int cpu)
 347 {
 348         struct task_struct *p;
 349
 350         /* create a process for the processor */
 351         p = fork_idle(cpu);
 352         if (IS_ERR(p))
 353                 panic("failed fork for CPU %u: %li", cpu, PTR_ERR(p));
 354         paca[cpu].__current = p;
 355         current_set[cpu] = p->thread_info;
 356 }
 357
 358 void __init smp_prepare_cpus(unsigned int max_cpus)
 359 {
 360         unsigned int cpu;
 361
 362         DBG("smp_prepare_cpus\n");
 363
 364         /*
 365          * setup_cpu may need to be called on the boot cpu. We havent
 366          * spun any cpus up but lets be paranoid.
 367          */
 368         BUG_ON(boot_cpuid != smp_processor_id());
 369
 370         /* Fixup boot cpu */
 371         smp_store_cpu_info(boot_cpuid);
 372         cpu_callin_map[boot_cpuid] = 1;
 373
 374 #ifndef CONFIG_PPC_ISERIES
 375         paca[boot_cpuid].next_jiffy_update_tb = tb_last_stamp = get_tb();
 376
 377         /*
 378          * Should update do_gtod.stamp_xsec.
 379          * For now we leave it which means the time can be some
 380          * number of msecs off until someone does a settimeofday()
 381          */
 382         do_gtod.varp->tb_orig_stamp = tb_last_stamp;
 383         systemcfg->tb_orig_stamp = tb_last_stamp;
 384 #endif
 385
 386         max_cpus = smp_ops->probe();
 387
 388         smp_space_timers(max_cpus);
 389
 390         for_each_cpu(cpu)
 391                 if (cpu != boot_cpuid)
 392                         smp_create_idle(cpu);
 393 }
 394
 395 void __devinit smp_prepare_boot_cpu(void)
 396 {
 397         BUG_ON(smp_processor_id() != boot_cpuid);
 398
 399         cpu_set(boot_cpuid, cpu_online_map);
 400
 401         paca[boot_cpuid].__current = current;
 402         current_set[boot_cpuid] = current->thread_info;
 403 }
 404
 405 #ifdef CONFIG_HOTPLUG_CPU
 406 /* State of each CPU during hotplug phases */
 407 DEFINE_PER_CPU(int, cpu_state) = { 0 };
 408
 409 int generic_cpu_disable(void)
 410 {
 411         unsigned int cpu = smp_processor_id();
 412
 413         if (cpu == boot_cpuid)
 414                 return -EBUSY;
 415
 416         systemcfg->processorCount--;
 417         cpu_clear(cpu, cpu_online_map);
 418         fixup_irqs(cpu_online_map);
 419         return 0;
 420 }
 421
 422 int generic_cpu_enable(unsigned int cpu)
 423 {
 424         /* Do the normal bootup if we haven't
 425          * already bootstrapped. */
 426         if (system_state != SYSTEM_RUNNING)
 427                 return -ENOSYS;
 428
 429         /* get the target out of it's holding state */
 430         per_cpu(cpu_state, cpu) = CPU_UP_PREPARE;
 431         smp_wmb();
 432
 433         while (!cpu_online(cpu))
 434                 cpu_relax();
 435
 436         fixup_irqs(cpu_online_map);
 437         /* counter the irq disable in fixup_irqs */
 438         local_irq_enable();
 439         return 0;
 440 }
 441
 442 void generic_cpu_die(unsigned int cpu)
 443 {
 444         int i;
 445
 446         for (i = 0; i < 100; i++) {
 447                 smp_rmb();
 448                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
 449                         return;
 450                 msleep(100);
 451         }
 452         printk(KERN_ERR "CPU%d didn't die...\n", cpu);
 453 }
 454
 455 void generic_mach_cpu_die(void)
 456 {
 457         unsigned int cpu;
 458
 459         local_irq_disable();
 460         cpu = smp_processor_id();
 461         printk(KERN_DEBUG "CPU%d offline\n", cpu);
 462         __get_cpu_var(cpu_state) = CPU_DEAD;
 463         smp_wmb();
 464         while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 465                 cpu_relax();
 466
 467         flush_tlb_pending();
 468         cpu_set(cpu, cpu_online_map);
 469         local_irq_enable();
 470 }
 471 #endif
 472
 473 static int __devinit cpu_enable(unsigned int cpu)
 474 {
 475         if (smp_ops->cpu_enable)
 476                 return smp_ops->cpu_enable(cpu);
 477
 478         return -ENOSYS;
 479 }
 480
 481 int __devinit __cpu_up(unsigned int cpu)
 482 {
 483         int c;
 484
 485         if (!cpu_enable(cpu))
 486                 return 0;
 487
 488         if (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu))
 489                 return -EINVAL;
 490
 491         paca[cpu].default_decr = tb_ticks_per_jiffy;
 492
 493         /* Make sure callin-map entry is 0 (can be leftover a CPU
 494          * hotplug
 495          */
 496         cpu_callin_map[cpu] = 0;
 497
 498         /* The information for processor bringup must
 499          * be written out to main store before we release
 500          * the processor.
 501          */
 502         smp_mb();
 503
 504         /* wake up cpus */
 505         DBG("smp: kicking cpu %d\n", cpu);
 506         smp_ops->kick_cpu(cpu);
 507
 508         /*
 509          * wait to see if the cpu made a callin (is actually up).
 510          * use this value that I found through experimentation.
 511          * -- Cort
 512          */
 513         if (system_state < SYSTEM_RUNNING)
 514                 for (c = 5000; c && !cpu_callin_map[cpu]; c--)
 515                         udelay(100);
 516 #ifdef CONFIG_HOTPLUG_CPU
 517         else
 518                 /*
 519                  * CPUs can take much longer to come up in the
 520                  * hotplug case.  Wait five seconds.
 521                  */
 522                 for (c = 25; c && !cpu_callin_map[cpu]; c--) {
 523                         msleep(200);
 524                 }
 525 #endif
 526
 527         if (!cpu_callin_map[cpu]) {
 528                 printk("Processor %u is stuck.\n", cpu);
 529                 return -ENOENT;
 530         }
 531
 532         printk("Processor %u found.\n", cpu);
 533
 534         if (smp_ops->give_timebase)
 535                 smp_ops->give_timebase();
 536
 537         /* Wait until cpu puts itself in the online map */
 538         while (!cpu_online(cpu))
 539                 cpu_relax();
 540
 541         return 0;
 542 }
 543
 544
 545 /* Activate a secondary processor. */
 546 int __devinit start_secondary(void *unused)
 547 {
 548         unsigned int cpu = smp_processor_id();
 549
 550         atomic_inc(&init_mm.mm_count);
 551         current->active_mm = &init_mm;
 552
 553         smp_store_cpu_info(cpu);
 554         set_dec(paca[cpu].default_decr);
 555         cpu_callin_map[cpu] = 1;
 556
 557         smp_ops->setup_cpu(cpu);
 558         if (smp_ops->take_timebase)
 559                 smp_ops->take_timebase();
 560
 561         spin_lock(&call_lock);
 562         cpu_set(cpu, cpu_online_map);
 563         spin_unlock(&call_lock);
 564
 565         local_irq_enable();
 566
 567         cpu_idle();
 568         return 0;
 569 }
 570
 571 int setup_profiling_timer(unsigned int multiplier)
 572 {
 573         return 0;
 574 }
 575
 576 void __init smp_cpus_done(unsigned int max_cpus)
 577 {
 578         cpumask_t old_mask;
 579
 580         /* We want the setup_cpu() here to be called from CPU 0, but our
 581          * init thread may have been "borrowed" by another CPU in the meantime
 582          * se we pin us down to CPU 0 for a short while
 583          */
 584         old_mask = current->cpus_allowed;
 585         set_cpus_allowed(current, cpumask_of_cpu(boot_cpuid));
 586
 587         smp_ops->setup_cpu(boot_cpuid);
 588
 589         set_cpus_allowed(current, old_mask);
 590 }
 591
 592 #ifdef CONFIG_HOTPLUG_CPU
 593 int __cpu_disable(void)
 594 {
 595         if (smp_ops->cpu_disable)
 596                 return smp_ops->cpu_disable();
 597
 598         return -ENOSYS;
 599 }
 600
 601 void __cpu_die(unsigned int cpu)
 602 {
 603         if (smp_ops->cpu_die)
 604                 smp_ops->cpu_die(cpu);
 605 }
 606 #endif