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/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/sched.h>
  23 #include <linux/smp.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/delay.h>
  26 #include <linux/init.h>
  27 #include <linux/spinlock.h>
  28 #include <linux/cache.h>
  29 #include <linux/err.h>
  30 #include <linux/sysdev.h>
  31 #include <linux/cpu.h>
  32 #include <linux/notifier.h>
  33 #include <linux/topology.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/cputhreads.h>
  45 #include <asm/cputable.h>
  46 #include <asm/system.h>
  47 #include <asm/mpic.h>
  48 #include <asm/vdso_datapage.h>
  49 #ifdef CONFIG_PPC64
  50 #include <asm/paca.h>
  51 #endif
  52
  53 #ifdef DEBUG
  54 #include <asm/udbg.h>
  55 #define DBG(fmt...) udbg_printf(fmt)
  56 #else
  57 #define DBG(fmt...)
  58 #endif
  59
  60
  61 /* Store all idle threads, this can be reused instead of creating
  62 * a new thread. Also avoids complicated thread destroy functionality
  63 * for idle threads.
  64 */
  65 #ifdef CONFIG_HOTPLUG_CPU
  66 /*
  67  * Needed only for CONFIG_HOTPLUG_CPU because __cpuinitdata is
  68  * removed after init for !CONFIG_HOTPLUG_CPU.
  69  */
  70 static DEFINE_PER_CPU(struct task_struct *, idle_thread_array);
  71 #define get_idle_for_cpu(x)      (per_cpu(idle_thread_array, x))
  72 #define set_idle_for_cpu(x, p)   (per_cpu(idle_thread_array, x) = (p))
  73 #else
  74 static struct task_struct *idle_thread_array[NR_CPUS] __cpuinitdata ;
  75 #define get_idle_for_cpu(x)      (idle_thread_array[(x)])
  76 #define set_idle_for_cpu(x, p)   (idle_thread_array[(x)] = (p))
  77 #endif
  78
  79 struct thread_info *secondary_ti;
  80
  81 DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
  82 DEFINE_PER_CPU(cpumask_var_t, cpu_core_map);
  83
  84 EXPORT_PER_CPU_SYMBOL(cpu_sibling_map);
  85 EXPORT_PER_CPU_SYMBOL(cpu_core_map);
  86
  87 /* SMP operations for this machine */
  88 struct smp_ops_t *smp_ops;
  89
  90 /* Can't be static due to PowerMac hackery */
  91 volatile unsigned int cpu_callin_map[NR_CPUS];
  92
  93 int smt_enabled_at_boot = 1;
  94
  95 static void (*crash_ipi_function_ptr)(struct pt_regs *) = NULL;
  96
  97 #ifdef CONFIG_PPC64
  98 int __devinit smp_generic_kick_cpu(int nr)
  99 {
 100         BUG_ON(nr < 0 || nr >= NR_CPUS);
 101
 102         /*
 103          * The processor is currently spinning, waiting for the
 104          * cpu_start field to become non-zero After we set cpu_start,
 105          * the processor will continue on to secondary_start
 106          */
 107         paca[nr].cpu_start = 1;
 108         smp_mb();
 109
 110         return 0;
 111 }
 112 #endif
 113
 114 static irqreturn_t call_function_action(int irq, void *data)
 115 {
 116         generic_smp_call_function_interrupt();
 117         return IRQ_HANDLED;
 118 }
 119
 120 static irqreturn_t reschedule_action(int irq, void *data)
 121 {
 122         scheduler_ipi();
 123         return IRQ_HANDLED;
 124 }
 125
 126 static irqreturn_t call_function_single_action(int irq, void *data)
 127 {
 128         generic_smp_call_function_single_interrupt();
 129         return IRQ_HANDLED;
 130 }
 131
 132 static irqreturn_t debug_ipi_action(int irq, void *data)
 133 {
 134         if (crash_ipi_function_ptr) {
 135                 crash_ipi_function_ptr(get_irq_regs());
 136                 return IRQ_HANDLED;
 137         }
 138
 139 #ifdef CONFIG_DEBUGGER
 140         debugger_ipi(get_irq_regs());
 141 #endif /* CONFIG_DEBUGGER */
 142
 143         return IRQ_HANDLED;
 144 }
 145
 146 static irq_handler_t smp_ipi_action[] = {
 147         [PPC_MSG_CALL_FUNCTION] =  call_function_action,
 148         [PPC_MSG_RESCHEDULE] = reschedule_action,
 149         [PPC_MSG_CALL_FUNC_SINGLE] = call_function_single_action,
 150         [PPC_MSG_DEBUGGER_BREAK] = debug_ipi_action,
 151 };
 152
 153 const char *smp_ipi_name[] = {
 154         [PPC_MSG_CALL_FUNCTION] =  "ipi call function",
 155         [PPC_MSG_RESCHEDULE] = "ipi reschedule",
 156         [PPC_MSG_CALL_FUNC_SINGLE] = "ipi call function single",
 157         [PPC_MSG_DEBUGGER_BREAK] = "ipi debugger",
 158 };
 159
 160 /* optional function to request ipi, for controllers with >= 4 ipis */
 161 int smp_request_message_ipi(int virq, int msg)
 162 {
 163         int err;
 164
 165         if (msg < 0 || msg > PPC_MSG_DEBUGGER_BREAK) {
 166                 return -EINVAL;
 167         }
 168 #if !defined(CONFIG_DEBUGGER) && !defined(CONFIG_KEXEC)
 169         if (msg == PPC_MSG_DEBUGGER_BREAK) {
 170                 return 1;
 171         }
 172 #endif
 173         err = request_irq(virq, smp_ipi_action[msg], IRQF_DISABLED|IRQF_PERCPU,
 174                           smp_ipi_name[msg], 0);
 175         WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n",
 176                 virq, smp_ipi_name[msg], err);
 177
 178         return err;
 179 }
 180
 181 #ifdef CONFIG_PPC_SMP_MUXED_IPI
 182 struct cpu_messages {
 183         int messages;                   /* current messages */
 184         unsigned long data;             /* data for cause ipi */
 185 };
 186 static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_messages, ipi_message);
 187
 188 void smp_muxed_ipi_set_data(int cpu, unsigned long data)
 189 {
 190         struct cpu_messages *info = &per_cpu(ipi_message, cpu);
 191
 192         info->data = data;
 193 }
 194
 195 void smp_muxed_ipi_message_pass(int cpu, int msg)
 196 {
 197         struct cpu_messages *info = &per_cpu(ipi_message, cpu);
 198         char *message = (char *)&info->messages;
 199
 200         message[msg] = 1;
 201         mb();
 202         smp_ops->cause_ipi(cpu, info->data);
 203 }
 204
 205 void smp_muxed_ipi_resend(void)
 206 {
 207         struct cpu_messages *info = &__get_cpu_var(ipi_message);
 208
 209         if (info->messages)
 210                 smp_ops->cause_ipi(smp_processor_id(), info->data);
 211 }
 212
 213 irqreturn_t smp_ipi_demux(void)
 214 {
 215         struct cpu_messages *info = &__get_cpu_var(ipi_message);
 216         unsigned int all;
 217
 218         mb();   /* order any irq clear */
 219
 220         do {
 221                 all = xchg_local(&info->messages, 0);
 222
 223 #ifdef __BIG_ENDIAN
 224                 if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNCTION)))
 225                         generic_smp_call_function_interrupt();
 226                 if (all & (1 << (24 - 8 * PPC_MSG_RESCHEDULE)))
 227                         scheduler_ipi();
 228                 if (all & (1 << (24 - 8 * PPC_MSG_CALL_FUNC_SINGLE)))
 229                         generic_smp_call_function_single_interrupt();
 230                 if (all & (1 << (24 - 8 * PPC_MSG_DEBUGGER_BREAK)))
 231                         debug_ipi_action(0, NULL);
 232 #else
 233 #error Unsupported ENDIAN
 234 #endif
 235         } while (info->messages);
 236
 237         return IRQ_HANDLED;
 238 }
 239 #endif /* CONFIG_PPC_SMP_MUXED_IPI */
 240
 241 static inline void do_message_pass(int cpu, int msg)
 242 {
 243         if (smp_ops->message_pass)
 244                 smp_ops->message_pass(cpu, msg);
 245 #ifdef CONFIG_PPC_SMP_MUXED_IPI
 246         else
 247                 smp_muxed_ipi_message_pass(cpu, msg);
 248 #endif
 249 }
 250
 251 void smp_send_reschedule(int cpu)
 252 {
 253         if (likely(smp_ops))
 254                 do_message_pass(cpu, PPC_MSG_RESCHEDULE);
 255 }
 256
 257 void arch_send_call_function_single_ipi(int cpu)
 258 {
 259         do_message_pass(cpu, PPC_MSG_CALL_FUNC_SINGLE);
 260 }
 261
 262 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 263 {
 264         unsigned int cpu;
 265
 266         for_each_cpu(cpu, mask)
 267                 do_message_pass(cpu, PPC_MSG_CALL_FUNCTION);
 268 }
 269
 270 #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
 271 void smp_send_debugger_break(void)
 272 {
 273         int cpu;
 274         int me = raw_smp_processor_id();
 275
 276         if (unlikely(!smp_ops))
 277                 return;
 278
 279         for_each_online_cpu(cpu)
 280                 if (cpu != me)
 281                         do_message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
 282 }
 283 #endif
 284
 285 #ifdef CONFIG_KEXEC
 286 void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
 287 {
 288         crash_ipi_function_ptr = crash_ipi_callback;
 289         if (crash_ipi_callback) {
 290                 mb();
 291                 smp_send_debugger_break();
 292         }
 293 }
 294 #endif
 295
 296 static void stop_this_cpu(void *dummy)
 297 {
 298         /* Remove this CPU */
 299         set_cpu_online(smp_processor_id(), false);
 300
 301         local_irq_disable();
 302         while (1)
 303                 ;
 304 }
 305
 306 void smp_send_stop(void)
 307 {
 308         smp_call_function(stop_this_cpu, NULL, 0);
 309 }
 310
 311 struct thread_info *current_set[NR_CPUS];
 312
 313 static void __devinit smp_store_cpu_info(int id)
 314 {
 315         per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR);
 316 }
 317
 318 void __init smp_prepare_cpus(unsigned int max_cpus)
 319 {
 320         unsigned int cpu;
 321
 322         DBG("smp_prepare_cpus\n");
 323
 324         /*
 325          * setup_cpu may need to be called on the boot cpu. We havent
 326          * spun any cpus up but lets be paranoid.
 327          */
 328         BUG_ON(boot_cpuid != smp_processor_id());
 329
 330         /* Fixup boot cpu */
 331         smp_store_cpu_info(boot_cpuid);
 332         cpu_callin_map[boot_cpuid] = 1;
 333
 334         for_each_possible_cpu(cpu) {
 335                 zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu),
 336                                         GFP_KERNEL, cpu_to_node(cpu));
 337                 zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu),
 338                                         GFP_KERNEL, cpu_to_node(cpu));
 339         }
 340
 341         cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
 342         cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid));
 343
 344         if (smp_ops)
 345                 if (smp_ops->probe)
 346                         max_cpus = smp_ops->probe();
 347                 else
 348                         max_cpus = NR_CPUS;
 349         else
 350                 max_cpus = 1;
 351 }
 352
 353 void __devinit smp_prepare_boot_cpu(void)
 354 {
 355         BUG_ON(smp_processor_id() != boot_cpuid);
 356 #ifdef CONFIG_PPC64
 357         paca[boot_cpuid].__current = current;
 358 #endif
 359         current_set[boot_cpuid] = task_thread_info(current);
 360 }
 361
 362 #ifdef CONFIG_HOTPLUG_CPU
 363 /* State of each CPU during hotplug phases */
 364 static 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         set_cpu_online(cpu, false);
 374 #ifdef CONFIG_PPC64
 375         vdso_data->processorCount--;
 376 #endif
 377         migrate_irqs();
 378         return 0;
 379 }
 380
 381 void generic_cpu_die(unsigned int cpu)
 382 {
 383         int i;
 384
 385         for (i = 0; i < 100; i++) {
 386                 smp_rmb();
 387                 if (per_cpu(cpu_state, cpu) == CPU_DEAD)
 388                         return;
 389                 msleep(100);
 390         }
 391         printk(KERN_ERR "CPU%d didn't die...\n", cpu);
 392 }
 393
 394 void generic_mach_cpu_die(void)
 395 {
 396         unsigned int cpu;
 397
 398         local_irq_disable();
 399         idle_task_exit();
 400         cpu = smp_processor_id();
 401         printk(KERN_DEBUG "CPU%d offline\n", cpu);
 402         __get_cpu_var(cpu_state) = CPU_DEAD;
 403         smp_wmb();
 404         while (__get_cpu_var(cpu_state) != CPU_UP_PREPARE)
 405                 cpu_relax();
 406 }
 407
 408 void generic_set_cpu_dead(unsigned int cpu)
 409 {
 410         per_cpu(cpu_state, cpu) = CPU_DEAD;
 411 }
 412 #endif
 413
 414 struct create_idle {
 415         struct work_struct work;
 416         struct task_struct *idle;
 417         struct completion done;
 418         int cpu;
 419 };
 420
 421 static void __cpuinit do_fork_idle(struct work_struct *work)
 422 {
 423         struct create_idle *c_idle =
 424                 container_of(work, struct create_idle, work);
 425
 426         c_idle->idle = fork_idle(c_idle->cpu);
 427         complete(&c_idle->done);
 428 }
 429
 430 static int __cpuinit create_idle(unsigned int cpu)
 431 {
 432         struct thread_info *ti;
 433         struct create_idle c_idle = {
 434                 .cpu    = cpu,
 435                 .done   = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
 436         };
 437         INIT_WORK_ONSTACK(&c_idle.work, do_fork_idle);
 438
 439         c_idle.idle = get_idle_for_cpu(cpu);
 440
 441         /* We can't use kernel_thread since we must avoid to
 442          * reschedule the child. We use a workqueue because
 443          * we want to fork from a kernel thread, not whatever
 444          * userspace process happens to be trying to online us.
 445          */
 446         if (!c_idle.idle) {
 447                 schedule_work(&c_idle.work);
 448                 wait_for_completion(&c_idle.done);
 449         } else
 450                 init_idle(c_idle.idle, cpu);
 451         if (IS_ERR(c_idle.idle)) {
 452                 pr_err("Failed fork for CPU %u: %li", cpu, PTR_ERR(c_idle.idle));
 453                 return PTR_ERR(c_idle.idle);
 454         }
 455         ti = task_thread_info(c_idle.idle);
 456
 457 #ifdef CONFIG_PPC64
 458         paca[cpu].__current = c_idle.idle;
 459         paca[cpu].kstack = (unsigned long)ti + THREAD_SIZE - STACK_FRAME_OVERHEAD;
 460 #endif
 461         ti->cpu = cpu;
 462         current_set[cpu] = ti;
 463
 464         return 0;
 465 }
 466
 467 int __cpuinit __cpu_up(unsigned int cpu)
 468 {
 469         int rc, c;
 470
 471         if (smp_ops == NULL ||
 472             (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu)))
 473                 return -EINVAL;
 474
 475         /* Make sure we have an idle thread */
 476         rc = create_idle(cpu);
 477         if (rc)
 478                 return rc;
 479
 480         secondary_ti = current_set[cpu];
 481
 482         /* Make sure callin-map entry is 0 (can be leftover a CPU
 483          * hotplug
 484          */
 485         cpu_callin_map[cpu] = 0;
 486
 487         /* The information for processor bringup must
 488          * be written out to main store before we release
 489          * the processor.
 490          */
 491         smp_mb();
 492
 493         /* wake up cpus */
 494         DBG("smp: kicking cpu %d\n", cpu);
 495         rc = smp_ops->kick_cpu(cpu);
 496         if (rc) {
 497                 pr_err("smp: failed starting cpu %d (rc %d)\n", cpu, rc);
 498                 return rc;
 499         }
 500
 501         /*
 502          * wait to see if the cpu made a callin (is actually up).
 503          * use this value that I found through experimentation.
 504          * -- Cort
 505          */
 506         if (system_state < SYSTEM_RUNNING)
 507                 for (c = 50000; c && !cpu_callin_map[cpu]; c--)
 508                         udelay(100);
 509 #ifdef CONFIG_HOTPLUG_CPU
 510         else
 511                 /*
 512                  * CPUs can take much longer to come up in the
 513                  * hotplug case.  Wait five seconds.
 514                  */
 515                 for (c = 5000; c && !cpu_callin_map[cpu]; c--)
 516                         msleep(1);
 517 #endif
 518
 519         if (!cpu_callin_map[cpu]) {
 520                 printk(KERN_ERR "Processor %u is stuck.\n", cpu);
 521                 return -ENOENT;
 522         }
 523
 524         DBG("Processor %u found.\n", cpu);
 525
 526         if (smp_ops->give_timebase)
 527                 smp_ops->give_timebase();
 528
 529         /* Wait until cpu puts itself in the online map */
 530         while (!cpu_online(cpu))
 531                 cpu_relax();
 532
 533         return 0;
 534 }
 535
 536 /* Return the value of the reg property corresponding to the given
 537  * logical cpu.
 538  */
 539 int cpu_to_core_id(int cpu)
 540 {
 541         struct device_node *np;
 542         const int *reg;
 543         int id = -1;
 544
 545         np = of_get_cpu_node(cpu, NULL);
 546         if (!np)
 547                 goto out;
 548
 549         reg = of_get_property(np, "reg", NULL);
 550         if (!reg)
 551                 goto out;
 552
 553         id = *reg;
 554 out:
 555         of_node_put(np);
 556         return id;
 557 }
 558
 559 /* Helper routines for cpu to core mapping */
 560 int cpu_core_index_of_thread(int cpu)
 561 {
 562         return cpu >> threads_shift;
 563 }
 564 EXPORT_SYMBOL_GPL(cpu_core_index_of_thread);
 565
 566 int cpu_first_thread_of_core(int core)
 567 {
 568         return core << threads_shift;
 569 }
 570 EXPORT_SYMBOL_GPL(cpu_first_thread_of_core);
 571
 572 /* Must be called when no change can occur to cpu_present_mask,
 573  * i.e. during cpu online or offline.
 574  */
 575 static struct device_node *cpu_to_l2cache(int cpu)
 576 {
 577         struct device_node *np;
 578         struct device_node *cache;
 579
 580         if (!cpu_present(cpu))
 581                 return NULL;
 582
 583         np = of_get_cpu_node(cpu, NULL);
 584         if (np == NULL)
 585                 return NULL;
 586
 587         cache = of_find_next_cache_node(np);
 588
 589         of_node_put(np);
 590
 591         return cache;
 592 }
 593
 594 /* Activate a secondary processor. */
 595 void __devinit start_secondary(void *unused)
 596 {
 597         unsigned int cpu = smp_processor_id();
 598         struct device_node *l2_cache;
 599         int i, base;
 600
 601         atomic_inc(&init_mm.mm_count);
 602         current->active_mm = &init_mm;
 603
 604         smp_store_cpu_info(cpu);
 605         set_dec(tb_ticks_per_jiffy);
 606         preempt_disable();
 607         cpu_callin_map[cpu] = 1;
 608
 609         if (smp_ops->setup_cpu)
 610                 smp_ops->setup_cpu(cpu);
 611         if (smp_ops->take_timebase)
 612                 smp_ops->take_timebase();
 613
 614         secondary_cpu_time_init();
 615
 616 #ifdef CONFIG_PPC64
 617         if (system_state == SYSTEM_RUNNING)
 618                 vdso_data->processorCount++;
 619 #endif
 620         ipi_call_lock();
 621         notify_cpu_starting(cpu);
 622         set_cpu_online(cpu, true);
 623         /* Update sibling maps */
 624         base = cpu_first_thread_sibling(cpu);
 625         for (i = 0; i < threads_per_core; i++) {
 626                 if (cpu_is_offline(base + i))
 627                         continue;
 628                 cpumask_set_cpu(cpu, cpu_sibling_mask(base + i));
 629                 cpumask_set_cpu(base + i, cpu_sibling_mask(cpu));
 630
 631                 /* cpu_core_map should be a superset of
 632                  * cpu_sibling_map even if we don't have cache
 633                  * information, so update the former here, too.
 634                  */
 635                 cpumask_set_cpu(cpu, cpu_core_mask(base + i));
 636                 cpumask_set_cpu(base + i, cpu_core_mask(cpu));
 637         }
 638         l2_cache = cpu_to_l2cache(cpu);
 639         for_each_online_cpu(i) {
 640                 struct device_node *np = cpu_to_l2cache(i);
 641                 if (!np)
 642                         continue;
 643                 if (np == l2_cache) {
 644                         cpumask_set_cpu(cpu, cpu_core_mask(i));
 645                         cpumask_set_cpu(i, cpu_core_mask(cpu));
 646                 }
 647                 of_node_put(np);
 648         }
 649         of_node_put(l2_cache);
 650         ipi_call_unlock();
 651
 652         local_irq_enable();
 653
 654         cpu_idle();
 655
 656         BUG();
 657 }
 658
 659 int setup_profiling_timer(unsigned int multiplier)
 660 {
 661         return 0;
 662 }
 663
 664 void __init smp_cpus_done(unsigned int max_cpus)
 665 {
 666         cpumask_var_t old_mask;
 667
 668         /* We want the setup_cpu() here to be called from CPU 0, but our
 669          * init thread may have been "borrowed" by another CPU in the meantime
 670          * se we pin us down to CPU 0 for a short while
 671          */
 672         alloc_cpumask_var(&old_mask, GFP_NOWAIT);
 673         cpumask_copy(old_mask, tsk_cpus_allowed(current));
 674         set_cpus_allowed_ptr(current, cpumask_of(boot_cpuid));
 675
 676         if (smp_ops && smp_ops->setup_cpu)
 677                 smp_ops->setup_cpu(boot_cpuid);
 678
 679         set_cpus_allowed_ptr(current, old_mask);
 680
 681         free_cpumask_var(old_mask);
 682
 683         if (smp_ops && smp_ops->bringup_done)
 684                 smp_ops->bringup_done();
 685
 686         dump_numa_cpu_topology();
 687
 688 }
 689
 690 int arch_sd_sibling_asym_packing(void)
 691 {
 692         if (cpu_has_feature(CPU_FTR_ASYM_SMT)) {
 693                 printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n");
 694                 return SD_ASYM_PACKING;
 695         }
 696         return 0;
 697 }
 698
 699 #ifdef CONFIG_HOTPLUG_CPU
 700 int __cpu_disable(void)
 701 {
 702         struct device_node *l2_cache;
 703         int cpu = smp_processor_id();
 704         int base, i;
 705         int err;
 706
 707         if (!smp_ops->cpu_disable)
 708                 return -ENOSYS;
 709
 710         err = smp_ops->cpu_disable();
 711         if (err)
 712                 return err;
 713
 714         /* Update sibling maps */
 715         base = cpu_first_thread_sibling(cpu);
 716         for (i = 0; i < threads_per_core; i++) {
 717                 cpumask_clear_cpu(cpu, cpu_sibling_mask(base + i));
 718                 cpumask_clear_cpu(base + i, cpu_sibling_mask(cpu));
 719                 cpumask_clear_cpu(cpu, cpu_core_mask(base + i));
 720                 cpumask_clear_cpu(base + i, cpu_core_mask(cpu));
 721         }
 722
 723         l2_cache = cpu_to_l2cache(cpu);
 724         for_each_present_cpu(i) {
 725                 struct device_node *np = cpu_to_l2cache(i);
 726                 if (!np)
 727                         continue;
 728                 if (np == l2_cache) {
 729                         cpumask_clear_cpu(cpu, cpu_core_mask(i));
 730                         cpumask_clear_cpu(i, cpu_core_mask(cpu));
 731                 }
 732                 of_node_put(np);
 733         }
 734         of_node_put(l2_cache);
 735
 736
 737         return 0;
 738 }
 739
 740 void __cpu_die(unsigned int cpu)
 741 {
 742         if (smp_ops->cpu_die)
 743                 smp_ops->cpu_die(cpu);
 744 }
 745
 746 static DEFINE_MUTEX(powerpc_cpu_hotplug_driver_mutex);
 747
 748 void cpu_hotplug_driver_lock()
 749 {
 750         mutex_lock(&powerpc_cpu_hotplug_driver_mutex);
 751 }
 752
 753 void cpu_hotplug_driver_unlock()
 754 {
 755         mutex_unlock(&powerpc_cpu_hotplug_driver_mutex);
 756 }
 757
 758 void cpu_die(void)
 759 {
 760         if (ppc_md.cpu_die)
 761                 ppc_md.cpu_die();
 762
 763         /* If we return, we re-enter start_secondary */
 764         start_secondary_resume();
 765 }
 766
 767 #endif