arch/arm/kernel/smp.c

   1 /*
   2  *  linux/arch/arm/kernel/smp.c
   3  *
   4  *  Copyright (C) 2002 ARM Limited, All Rights Reserved.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/config.h>
  11 #include <linux/delay.h>
  12 #include <linux/init.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/sched.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/cache.h>
  17 #include <linux/profile.h>
  18 #include <linux/errno.h>
  19 #include <linux/mm.h>
  20 #include <linux/cpu.h>
  21 #include <linux/smp.h>
  22 #include <linux/seq_file.h>
  23
  24 #include <asm/atomic.h>
  25 #include <asm/cacheflush.h>
  26 #include <asm/cpu.h>
  27 #include <asm/mmu_context.h>
  28 #include <asm/pgtable.h>
  29 #include <asm/pgalloc.h>
  30 #include <asm/processor.h>
  31 #include <asm/tlbflush.h>
  32 #include <asm/ptrace.h>
  33
  34 /*
  35  * bitmask of present and online CPUs.
  36  * The present bitmask indicates that the CPU is physically present.
  37  * The online bitmask indicates that the CPU is up and running.
  38  */
  39 cpumask_t cpu_present_mask;
  40 cpumask_t cpu_online_map;
  41
  42 /*
  43  * as from 2.5, kernels no longer have an init_tasks structure
  44  * so we need some other way of telling a new secondary core
  45  * where to place its SVC stack
  46  */
  47 struct secondary_data secondary_data;
  48
  49 /*
  50  * structures for inter-processor calls
  51  * - A collection of single bit ipi messages.
  52  */
  53 struct ipi_data {
  54         spinlock_t lock;
  55         unsigned long ipi_count;
  56         unsigned long bits;
  57 };
  58
  59 static DEFINE_PER_CPU(struct ipi_data, ipi_data) = {
  60         .lock   = SPIN_LOCK_UNLOCKED,
  61 };
  62
  63 enum ipi_msg_type {
  64         IPI_TIMER,
  65         IPI_RESCHEDULE,
  66         IPI_CALL_FUNC,
  67         IPI_CPU_STOP,
  68 };
  69
  70 struct smp_call_struct {
  71         void (*func)(void *info);
  72         void *info;
  73         int wait;
  74         cpumask_t pending;
  75         cpumask_t unfinished;
  76 };
  77
  78 static struct smp_call_struct * volatile smp_call_function_data;
  79 static DEFINE_SPINLOCK(smp_call_function_lock);
  80
  81 int __init __cpu_up(unsigned int cpu)
  82 {
  83         struct task_struct *idle;
  84         pgd_t *pgd;
  85         pmd_t *pmd;
  86         int ret;
  87
  88         /*
  89          * Spawn a new process manually.  Grab a pointer to
  90          * its task struct so we can mess with it
  91          */
  92         idle = fork_idle(cpu);
  93         if (IS_ERR(idle)) {
  94                 printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
  95                 return PTR_ERR(idle);
  96         }
  97
  98         /*
  99          * Allocate initial page tables to allow the new CPU to
 100          * enable the MMU safely.  This essentially means a set
 101          * of our "standard" page tables, with the addition of
 102          * a 1:1 mapping for the physical address of the kernel.
 103          */
 104         pgd = pgd_alloc(&init_mm);
 105         pmd = pmd_offset(pgd, PHYS_OFFSET);
 106         *pmd = __pmd((PHYS_OFFSET & PGDIR_MASK) |
 107                      PMD_TYPE_SECT | PMD_SECT_AP_WRITE);
 108
 109         /*
 110          * We need to tell the secondary core where to find
 111          * its stack and the page tables.
 112          */
 113         secondary_data.stack = (void *)idle->thread_info + THREAD_SIZE - 8;
 114         secondary_data.pgdir = virt_to_phys(pgd);
 115         wmb();
 116
 117         /*
 118          * Now bring the CPU into our world.
 119          */
 120         ret = boot_secondary(cpu, idle);
 121         if (ret == 0) {
 122                 unsigned long timeout;
 123
 124                 /*
 125                  * CPU was successfully started, wait for it
 126                  * to come online or time out.
 127                  */
 128                 timeout = jiffies + HZ;
 129                 while (time_before(jiffies, timeout)) {
 130                         if (cpu_online(cpu))
 131                                 break;
 132
 133                         udelay(10);
 134                         barrier();
 135                 }
 136
 137                 if (!cpu_online(cpu))
 138                         ret = -EIO;
 139         }
 140
 141         secondary_data.stack = 0;
 142         secondary_data.pgdir = 0;
 143
 144         *pmd_offset(pgd, PHYS_OFFSET) = __pmd(0);
 145         pgd_free(pgd);
 146
 147         if (ret) {
 148                 printk(KERN_CRIT "cpu_up: processor %d failed to boot\n", cpu);
 149                 /*
 150                  * FIXME: We need to clean up the new idle thread. --rmk
 151                  */
 152         }
 153
 154         return ret;
 155 }
 156
 157 /*
 158  * This is the secondary CPU boot entry.  We're using this CPUs
 159  * idle thread stack, but a set of temporary page tables.
 160  */
 161 asmlinkage void __init secondary_start_kernel(void)
 162 {
 163         struct mm_struct *mm = &init_mm;
 164         unsigned int cpu = smp_processor_id();
 165
 166         printk("CPU%u: Booted secondary processor\n", cpu);
 167
 168         /*
 169          * All kernel threads share the same mm context; grab a
 170          * reference and switch to it.
 171          */
 172         atomic_inc(&mm->mm_users);
 173         atomic_inc(&mm->mm_count);
 174         current->active_mm = mm;
 175         cpu_set(cpu, mm->cpu_vm_mask);
 176         cpu_switch_mm(mm->pgd, mm);
 177         enter_lazy_tlb(mm, current);
 178
 179         cpu_init();
 180
 181         /*
 182          * Give the platform a chance to do its own initialisation.
 183          */
 184         platform_secondary_init(cpu);
 185
 186         /*
 187          * Enable local interrupts.
 188          */
 189         local_irq_enable();
 190         local_fiq_enable();
 191
 192         calibrate_delay();
 193
 194         smp_store_cpu_info(cpu);
 195
 196         /*
 197          * OK, now it's safe to let the boot CPU continue
 198          */
 199         cpu_set(cpu, cpu_online_map);
 200
 201         /*
 202          * OK, it's off to the idle thread for us
 203          */
 204         cpu_idle();
 205 }
 206
 207 /*
 208  * Called by both boot and secondaries to move global data into
 209  * per-processor storage.
 210  */
 211 void __init smp_store_cpu_info(unsigned int cpuid)
 212 {
 213         struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
 214
 215         cpu_info->loops_per_jiffy = loops_per_jiffy;
 216 }
 217
 218 void __init smp_cpus_done(unsigned int max_cpus)
 219 {
 220         int cpu;
 221         unsigned long bogosum = 0;
 222
 223         for_each_online_cpu(cpu)
 224                 bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
 225
 226         printk(KERN_INFO "SMP: Total of %d processors activated "
 227                "(%lu.%02lu BogoMIPS).\n",
 228                num_online_cpus(),
 229                bogosum / (500000/HZ),
 230                (bogosum / (5000/HZ)) % 100);
 231 }
 232
 233 void __init smp_prepare_boot_cpu(void)
 234 {
 235         unsigned int cpu = smp_processor_id();
 236
 237         cpu_set(cpu, cpu_present_mask);
 238         cpu_set(cpu, cpu_online_map);
 239 }
 240
 241 static void send_ipi_message(cpumask_t callmap, enum ipi_msg_type msg)
 242 {
 243         unsigned long flags;
 244         unsigned int cpu;
 245
 246         local_irq_save(flags);
 247
 248         for_each_cpu_mask(cpu, callmap) {
 249                 struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 250
 251                 spin_lock(&ipi->lock);
 252                 ipi->bits |= 1 << msg;
 253                 spin_unlock(&ipi->lock);
 254         }
 255
 256         /*
 257          * Call the platform specific cross-CPU call function.
 258          */
 259         smp_cross_call(callmap);
 260
 261         local_irq_restore(flags);
 262 }
 263
 264 /*
 265  * You must not call this function with disabled interrupts, from a
 266  * hardware interrupt handler, nor from a bottom half handler.
 267  */
 268 int smp_call_function_on_cpu(void (*func)(void *info), void *info, int retry,
 269                              int wait, cpumask_t callmap)
 270 {
 271         struct smp_call_struct data;
 272         unsigned long timeout;
 273         int ret = 0;
 274
 275         data.func = func;
 276         data.info = info;
 277         data.wait = wait;
 278
 279         cpu_clear(smp_processor_id(), callmap);
 280         if (cpus_empty(callmap))
 281                 goto out;
 282
 283         data.pending = callmap;
 284         if (wait)
 285                 data.unfinished = callmap;
 286
 287         /*
 288          * try to get the mutex on smp_call_function_data
 289          */
 290         spin_lock(&smp_call_function_lock);
 291         smp_call_function_data = &data;
 292
 293         send_ipi_message(callmap, IPI_CALL_FUNC);
 294
 295         timeout = jiffies + HZ;
 296         while (!cpus_empty(data.pending) && time_before(jiffies, timeout))
 297                 barrier();
 298
 299         /*
 300          * did we time out?
 301          */
 302         if (!cpus_empty(data.pending)) {
 303                 /*
 304                  * this may be causing our panic - report it
 305                  */
 306                 printk(KERN_CRIT
 307                        "CPU%u: smp_call_function timeout for %p(%p)\n"
 308                        "      callmap %lx pending %lx, %swait\n",
 309                        smp_processor_id(), func, info, callmap, data.pending,
 310                        wait ? "" : "no ");
 311
 312                 /*
 313                  * TRACE
 314                  */
 315                 timeout = jiffies + (5 * HZ);
 316                 while (!cpus_empty(data.pending) && time_before(jiffies, timeout))
 317                         barrier();
 318
 319                 if (cpus_empty(data.pending))
 320                         printk(KERN_CRIT "     RESOLVED\n");
 321                 else
 322                         printk(KERN_CRIT "     STILL STUCK\n");
 323         }
 324
 325         /*
 326          * whatever happened, we're done with the data, so release it
 327          */
 328         smp_call_function_data = NULL;
 329         spin_unlock(&smp_call_function_lock);
 330
 331         if (!cpus_empty(data.pending)) {
 332                 ret = -ETIMEDOUT;
 333                 goto out;
 334         }
 335
 336         if (wait)
 337                 while (!cpus_empty(data.unfinished))
 338                         barrier();
 339  out:
 340
 341         return 0;
 342 }
 343
 344 int smp_call_function(void (*func)(void *info), void *info, int retry,
 345                       int wait)
 346 {
 347         return smp_call_function_on_cpu(func, info, retry, wait,
 348                                         cpu_online_map);
 349 }
 350
 351 void show_ipi_list(struct seq_file *p)
 352 {
 353         unsigned int cpu;
 354
 355         seq_puts(p, "IPI:");
 356
 357         for_each_online_cpu(cpu)
 358                 seq_printf(p, " %10lu", per_cpu(ipi_data, cpu).ipi_count);
 359
 360         seq_putc(p, '\n');
 361 }
 362
 363 static void ipi_timer(struct pt_regs *regs)
 364 {
 365         int user = user_mode(regs);
 366
 367         irq_enter();
 368         profile_tick(CPU_PROFILING, regs);
 369         update_process_times(user);
 370         irq_exit();
 371 }
 372
 373 /*
 374  * ipi_call_function - handle IPI from smp_call_function()
 375  *
 376  * Note that we copy data out of the cross-call structure and then
 377  * let the caller know that we're here and have done with their data
 378  */
 379 static void ipi_call_function(unsigned int cpu)
 380 {
 381         struct smp_call_struct *data = smp_call_function_data;
 382         void (*func)(void *info) = data->func;
 383         void *info = data->info;
 384         int wait = data->wait;
 385
 386         cpu_clear(cpu, data->pending);
 387
 388         func(info);
 389
 390         if (wait)
 391                 cpu_clear(cpu, data->unfinished);
 392 }
 393
 394 static DEFINE_SPINLOCK(stop_lock);
 395
 396 /*
 397  * ipi_cpu_stop - handle IPI from smp_send_stop()
 398  */
 399 static void ipi_cpu_stop(unsigned int cpu)
 400 {
 401         spin_lock(&stop_lock);
 402         printk(KERN_CRIT "CPU%u: stopping\n", cpu);
 403         dump_stack();
 404         spin_unlock(&stop_lock);
 405
 406         cpu_clear(cpu, cpu_online_map);
 407
 408         local_fiq_disable();
 409         local_irq_disable();
 410
 411         while (1)
 412                 cpu_relax();
 413 }
 414
 415 /*
 416  * Main handler for inter-processor interrupts
 417  *
 418  * For ARM, the ipimask now only identifies a single
 419  * category of IPI (Bit 1 IPIs have been replaced by a
 420  * different mechanism):
 421  *
 422  *  Bit 0 - Inter-processor function call
 423  */
 424 void do_IPI(struct pt_regs *regs)
 425 {
 426         unsigned int cpu = smp_processor_id();
 427         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 428
 429         ipi->ipi_count++;
 430
 431         for (;;) {
 432                 unsigned long msgs;
 433
 434                 spin_lock(&ipi->lock);
 435                 msgs = ipi->bits;
 436                 ipi->bits = 0;
 437                 spin_unlock(&ipi->lock);
 438
 439                 if (!msgs)
 440                         break;
 441
 442                 do {
 443                         unsigned nextmsg;
 444
 445                         nextmsg = msgs & -msgs;
 446                         msgs &= ~nextmsg;
 447                         nextmsg = ffz(~nextmsg);
 448
 449                         switch (nextmsg) {
 450                         case IPI_TIMER:
 451                                 ipi_timer(regs);
 452                                 break;
 453
 454                         case IPI_RESCHEDULE:
 455                                 /*
 456                                  * nothing more to do - eveything is
 457                                  * done on the interrupt return path
 458                                  */
 459                                 break;
 460
 461                         case IPI_CALL_FUNC:
 462                                 ipi_call_function(cpu);
 463                                 break;
 464
 465                         case IPI_CPU_STOP:
 466                                 ipi_cpu_stop(cpu);
 467                                 break;
 468
 469                         default:
 470                                 printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
 471                                        cpu, nextmsg);
 472                                 break;
 473                         }
 474                 } while (msgs);
 475         }
 476 }
 477
 478 void smp_send_reschedule(int cpu)
 479 {
 480         send_ipi_message(cpumask_of_cpu(cpu), IPI_RESCHEDULE);
 481 }
 482
 483 void smp_send_timer(void)
 484 {
 485         cpumask_t mask = cpu_online_map;
 486         cpu_clear(smp_processor_id(), mask);
 487         send_ipi_message(mask, IPI_TIMER);
 488 }
 489
 490 void smp_send_stop(void)
 491 {
 492         cpumask_t mask = cpu_online_map;
 493         cpu_clear(smp_processor_id(), mask);
 494         send_ipi_message(mask, IPI_CPU_STOP);
 495 }
 496
 497 /*
 498  * not supported here
 499  */
 500 int __init setup_profiling_timer(unsigned int multiplier)
 501 {
 502         return -EINVAL;
 503 }