arch/parisc/kernel/smp.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3 ** SMP Support
   4 **
   5 ** Copyright (C) 1999 Walt Drummond <drummond@valinux.com>
   6 ** Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
   7 ** Copyright (C) 2001,2004 Grant Grundler <grundler@parisc-linux.org>
   8 **
   9 ** Lots of stuff stolen from arch/alpha/kernel/smp.c
  10 ** ...and then parisc stole from arch/ia64/kernel/smp.c. Thanks David! :^)
  11 **
  12 ** Thanks to John Curry and Ullas Ponnadi. I learned a lot from their work.
  13 ** -grant (1/12/2001)
  14 **
  15 */
  16 #include <linux/types.h>
  17 #include <linux/spinlock.h>
  18
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/sched/mm.h>
  22 #include <linux/init.h>
  23 #include <linux/interrupt.h>
  24 #include <linux/smp.h>
  25 #include <linux/kernel_stat.h>
  26 #include <linux/mm.h>
  27 #include <linux/err.h>
  28 #include <linux/delay.h>
  29 #include <linux/bitops.h>
  30 #include <linux/ftrace.h>
  31 #include <linux/cpu.h>
  32 #include <linux/kgdb.h>
  33 #include <linux/sched/hotplug.h>
  34
  35 #include <linux/atomic.h>
  36 #include <asm/current.h>
  37 #include <asm/delay.h>
  38 #include <asm/tlbflush.h>
  39
  40 #include <asm/io.h>
  41 #include <asm/irq.h>            /* for CPU_IRQ_REGION and friends */
  42 #include <asm/mmu_context.h>
  43 #include <asm/page.h>
  44 #include <asm/processor.h>
  45 #include <asm/ptrace.h>
  46 #include <asm/unistd.h>
  47 #include <asm/cacheflush.h>
  48
  49 #undef DEBUG_SMP
  50 #ifdef DEBUG_SMP
  51 static int smp_debug_lvl = 0;
  52 #define smp_debug(lvl, printargs...)            \
  53                 if (lvl >= smp_debug_lvl)       \
  54                         printk(printargs);
  55 #else
  56 #define smp_debug(lvl, ...)     do { } while(0)
  57 #endif /* DEBUG_SMP */
  58
  59 volatile struct task_struct *smp_init_current_idle_task;
  60
  61 /* track which CPU is booting */
  62 static volatile int cpu_now_booting;
  63
  64 static DEFINE_PER_CPU(spinlock_t, ipi_lock);
  65
  66 enum ipi_message_type {
  67         IPI_NOP=0,
  68         IPI_RESCHEDULE=1,
  69         IPI_CALL_FUNC,
  70         IPI_CPU_START,
  71         IPI_CPU_STOP,
  72         IPI_CPU_TEST,
  73 #ifdef CONFIG_KGDB
  74         IPI_ENTER_KGDB,
  75 #endif
  76 };
  77
  78
  79 /********** SMP inter processor interrupt and communication routines */
  80
  81 #undef PER_CPU_IRQ_REGION
  82 #ifdef PER_CPU_IRQ_REGION
  83 /* XXX REVISIT Ignore for now.
  84 **    *May* need this "hook" to register IPI handler
  85 **    once we have perCPU ExtIntr switch tables.
  86 */
  87 static void
  88 ipi_init(int cpuid)
  89 {
  90 #error verify IRQ_OFFSET(IPI_IRQ) is ipi_interrupt() in new IRQ region
  91
  92         if(cpu_online(cpuid) )
  93         {
  94                 switch_to_idle_task(current);
  95         }
  96
  97         return;
  98 }
  99 #endif
 100
 101
 102 /*
 103 ** Yoink this CPU from the runnable list...
 104 **
 105 */
 106 static void
 107 halt_processor(void)
 108 {
 109         /* REVISIT : redirect I/O Interrupts to another CPU? */
 110         /* REVISIT : does PM *know* this CPU isn't available? */
 111         set_cpu_online(smp_processor_id(), false);
 112         local_irq_disable();
 113         __pdc_cpu_rendezvous();
 114         for (;;)
 115                 ;
 116 }
 117
 118
 119 irqreturn_t __irq_entry
 120 ipi_interrupt(int irq, void *dev_id)
 121 {
 122         int this_cpu = smp_processor_id();
 123         struct cpuinfo_parisc *p = &per_cpu(cpu_data, this_cpu);
 124         unsigned long ops;
 125         unsigned long flags;
 126
 127         for (;;) {
 128                 spinlock_t *lock = &per_cpu(ipi_lock, this_cpu);
 129                 spin_lock_irqsave(lock, flags);
 130                 ops = p->pending_ipi;
 131                 p->pending_ipi = 0;
 132                 spin_unlock_irqrestore(lock, flags);
 133
 134                 mb(); /* Order bit clearing and data access. */
 135
 136                 if (!ops)
 137                     break;
 138
 139                 while (ops) {
 140                         unsigned long which = ffz(~ops);
 141
 142                         ops &= ~(1 << which);
 143
 144                         switch (which) {
 145                         case IPI_NOP:
 146                                 smp_debug(100, KERN_DEBUG "CPU%d IPI_NOP\n", this_cpu);
 147                                 break;
 148
 149                         case IPI_RESCHEDULE:
 150                                 smp_debug(100, KERN_DEBUG "CPU%d IPI_RESCHEDULE\n", this_cpu);
 151                                 inc_irq_stat(irq_resched_count);
 152                                 scheduler_ipi();
 153                                 break;
 154
 155                         case IPI_CALL_FUNC:
 156                                 smp_debug(100, KERN_DEBUG "CPU%d IPI_CALL_FUNC\n", this_cpu);
 157                                 inc_irq_stat(irq_call_count);
 158                                 generic_smp_call_function_interrupt();
 159                                 break;
 160
 161                         case IPI_CPU_START:
 162                                 smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_START\n", this_cpu);
 163                                 break;
 164
 165                         case IPI_CPU_STOP:
 166                                 smp_debug(100, KERN_DEBUG "CPU%d IPI_CPU_STOP\n", this_cpu);
 167                                 halt_processor();
 168                                 break;
 169
 170                         case IPI_CPU_TEST:
 171                                 smp_debug(100, KERN_DEBUG "CPU%d is alive!\n", this_cpu);
 172                                 break;
 173 #ifdef CONFIG_KGDB
 174                         case IPI_ENTER_KGDB:
 175                                 smp_debug(100, KERN_DEBUG "CPU%d ENTER_KGDB\n", this_cpu);
 176                                 kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 177                                 break;
 178 #endif
 179                         default:
 180                                 printk(KERN_CRIT "Unknown IPI num on CPU%d: %lu\n",
 181                                         this_cpu, which);
 182                                 return IRQ_NONE;
 183                         } /* Switch */
 184
 185                         /* before doing more, let in any pending interrupts */
 186                         if (ops) {
 187                                 local_irq_enable();
 188                                 local_irq_disable();
 189                         }
 190                 } /* while (ops) */
 191         }
 192         return IRQ_HANDLED;
 193 }
 194
 195
 196 static inline void
 197 ipi_send(int cpu, enum ipi_message_type op)
 198 {
 199         struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpu);
 200         spinlock_t *lock = &per_cpu(ipi_lock, cpu);
 201         unsigned long flags;
 202
 203         spin_lock_irqsave(lock, flags);
 204         p->pending_ipi |= 1 << op;
 205         gsc_writel(IPI_IRQ - CPU_IRQ_BASE, p->hpa);
 206         spin_unlock_irqrestore(lock, flags);
 207 }
 208
 209 static void
 210 send_IPI_mask(const struct cpumask *mask, enum ipi_message_type op)
 211 {
 212         int cpu;
 213
 214         for_each_cpu(cpu, mask)
 215                 ipi_send(cpu, op);
 216 }
 217
 218 static inline void
 219 send_IPI_single(int dest_cpu, enum ipi_message_type op)
 220 {
 221         BUG_ON(dest_cpu == NO_PROC_ID);
 222
 223         ipi_send(dest_cpu, op);
 224 }
 225
 226 static inline void
 227 send_IPI_allbutself(enum ipi_message_type op)
 228 {
 229         int i;
 230
 231         preempt_disable();
 232         for_each_online_cpu(i) {
 233                 if (i != smp_processor_id())
 234                         send_IPI_single(i, op);
 235         }
 236         preempt_enable();
 237 }
 238
 239 #ifdef CONFIG_KGDB
 240 void kgdb_roundup_cpus(void)
 241 {
 242         send_IPI_allbutself(IPI_ENTER_KGDB);
 243 }
 244 #endif
 245
 246 inline void
 247 smp_send_stop(void)     { send_IPI_allbutself(IPI_CPU_STOP); }
 248
 249 void
 250 arch_smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); }
 251
 252 void
 253 smp_send_all_nop(void)
 254 {
 255         send_IPI_allbutself(IPI_NOP);
 256 }
 257
 258 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 259 {
 260         send_IPI_mask(mask, IPI_CALL_FUNC);
 261 }
 262
 263 void arch_send_call_function_single_ipi(int cpu)
 264 {
 265         send_IPI_single(cpu, IPI_CALL_FUNC);
 266 }
 267
 268 /*
 269  * Called by secondaries to update state and initialize CPU registers.
 270  */
 271 static void
 272 smp_cpu_init(int cpunum)
 273 {
 274         /* Set modes and Enable floating point coprocessor */
 275         init_per_cpu(cpunum);
 276
 277         disable_sr_hashing();
 278
 279         mb();
 280
 281         /* Well, support 2.4 linux scheme as well. */
 282         if (cpu_online(cpunum)) {
 283                 extern void machine_halt(void); /* arch/parisc.../process.c */
 284
 285                 printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
 286                 machine_halt();
 287         }
 288
 289         notify_cpu_starting(cpunum);
 290
 291         set_cpu_online(cpunum, true);
 292
 293         /* Initialise the idle task for this CPU */
 294         mmgrab(&init_mm);
 295         current->active_mm = &init_mm;
 296         BUG_ON(current->mm);
 297         enter_lazy_tlb(&init_mm, current);
 298
 299         init_IRQ();   /* make sure no IRQs are enabled or pending */
 300         parisc_clockevent_init();
 301 }
 302
 303
 304 /*
 305  * Slaves start using C here. Indirectly called from smp_slave_stext.
 306  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
 307  */
 308 void smp_callin(unsigned long pdce_proc)
 309 {
 310         int slave_id = cpu_now_booting;
 311
 312 #ifdef CONFIG_64BIT
 313         WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
 314                         | PAGE0->mem_pdc) != pdce_proc);
 315 #endif
 316
 317         smp_cpu_init(slave_id);
 318
 319         flush_cache_all_local(); /* start with known state */
 320         flush_tlb_all_local(NULL);
 321
 322         local_irq_enable();  /* Interrupts have been off until now */
 323
 324         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 325
 326         /* NOTREACHED */
 327         panic("smp_callin() AAAAaaaaahhhh....\n");
 328 }
 329
 330 /*
 331  * Bring one cpu online.
 332  */
 333 static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
 334 {
 335         const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
 336         long timeout;
 337
 338 #ifdef CONFIG_HOTPLUG_CPU
 339         int i;
 340
 341         /* reset irq statistics for this CPU */
 342         memset(&per_cpu(irq_stat, cpuid), 0, sizeof(irq_cpustat_t));
 343         for (i = 0; i < NR_IRQS; i++) {
 344                 struct irq_desc *desc = irq_to_desc(i);
 345
 346                 if (desc && desc->kstat_irqs)
 347                         *per_cpu_ptr(desc->kstat_irqs, cpuid) = (struct irqstat) { };
 348         }
 349 #endif
 350
 351         /* wait until last booting CPU has started. */
 352         while (cpu_now_booting)
 353                 ;
 354
 355         /* Let _start know what logical CPU we're booting
 356         ** (offset into init_tasks[],cpu_data[])
 357         */
 358         cpu_now_booting = cpuid;
 359
 360         /*
 361         ** boot strap code needs to know the task address since
 362         ** it also contains the process stack.
 363         */
 364         smp_init_current_idle_task = idle ;
 365         mb();
 366
 367         printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
 368
 369         /*
 370         ** This gets PDC to release the CPU from a very tight loop.
 371         **
 372         ** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
 373         ** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
 374         ** is executed after receiving the rendezvous signal (an interrupt to
 375         ** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
 376         ** contents of memory are valid."
 377         */
 378         gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
 379         mb();
 380
 381         /*
 382          * OK, wait a bit for that CPU to finish staggering about.
 383          * Slave will set a bit when it reaches smp_cpu_init().
 384          * Once the "monarch CPU" sees the bit change, it can move on.
 385          */
 386         for (timeout = 0; timeout < 10000; timeout++) {
 387                 if(cpu_online(cpuid)) {
 388                         /* Which implies Slave has started up */
 389                         cpu_now_booting = 0;
 390                         goto alive ;
 391                 }
 392                 udelay(100);
 393                 barrier();
 394         }
 395         printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
 396         return -1;
 397
 398 alive:
 399         /* Remember the Slave data */
 400         smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
 401                 cpuid, timeout * 100);
 402         return 0;
 403 }
 404
 405 void __init smp_prepare_boot_cpu(void)
 406 {
 407         pr_info("SMP: bootstrap CPU ID is 0\n");
 408 }
 409
 410
 411
 412 /*
 413 ** inventory.c:do_inventory() hasn't yet been run and thus we
 414 ** don't 'discover' the additional CPUs until later.
 415 */
 416 void __init smp_prepare_cpus(unsigned int max_cpus)
 417 {
 418         int cpu;
 419
 420         for_each_possible_cpu(cpu)
 421                 spin_lock_init(&per_cpu(ipi_lock, cpu));
 422
 423         init_cpu_present(cpumask_of(0));
 424 }
 425
 426
 427 void __init smp_cpus_done(unsigned int cpu_max)
 428 {
 429 }
 430
 431
 432 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 433 {
 434         if (cpu_online(cpu))
 435                 return 0;
 436
 437         if (num_online_cpus() < nr_cpu_ids &&
 438                 num_online_cpus() < setup_max_cpus &&
 439                 smp_boot_one_cpu(cpu, tidle))
 440                 return -EIO;
 441
 442         return cpu_online(cpu) ? 0 : -EIO;
 443 }
 444
 445 /*
 446  * __cpu_disable runs on the processor to be shutdown.
 447  */
 448 int __cpu_disable(void)
 449 {
 450 #ifdef CONFIG_HOTPLUG_CPU
 451         unsigned int cpu = smp_processor_id();
 452
 453         remove_cpu_topology(cpu);
 454
 455         /*
 456          * Take this CPU offline.  Once we clear this, we can't return,
 457          * and we must not schedule until we're ready to give up the cpu.
 458          */
 459         set_cpu_online(cpu, false);
 460
 461         /* Find a new timesync master */
 462         if (cpu == time_keeper_id) {
 463                 time_keeper_id = cpumask_first(cpu_online_mask);
 464                 pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
 465         }
 466
 467         disable_percpu_irq(IPI_IRQ);
 468
 469         irq_migrate_all_off_this_cpu();
 470
 471         flush_cache_all_local();
 472         flush_tlb_all_local(NULL);
 473
 474         /* disable all irqs, including timer irq */
 475         local_irq_disable();
 476
 477         /* wait for next timer irq ... */
 478         mdelay(1000/HZ+100);
 479
 480         /* ... and then clear all pending external irqs */
 481         set_eiem(0);
 482         mtctl(~0UL, CR_EIRR);
 483         mfctl(CR_EIRR);
 484         mtctl(0, CR_EIRR);
 485 #endif
 486         return 0;
 487 }
 488
 489 /*
 490  * called on the thread which is asking for a CPU to be shutdown -
 491  * waits until shutdown has completed, or it is timed out.
 492  */
 493 void __cpu_die(unsigned int cpu)
 494 {
 495         pdc_cpu_rendezvous_lock();
 496 }
 497
 498 void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
 499 {
 500         pr_info("CPU%u: is shutting down\n", cpu);
 501
 502         /* set task's state to interruptible sleep */
 503         set_current_state(TASK_INTERRUPTIBLE);
 504         schedule_timeout((IS_ENABLED(CONFIG_64BIT) ? 8:2) * HZ);
 505
 506         pdc_cpu_rendezvous_unlock();
 507 }