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 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         extern void init_IRQ(void);    /* arch/parisc/kernel/irq.c */
 275         extern void start_cpu_itimer(void); /* arch/parisc/kernel/time.c */
 276
 277         /* Set modes and Enable floating point coprocessor */
 278         init_per_cpu(cpunum);
 279
 280         disable_sr_hashing();
 281
 282         mb();
 283
 284         /* Well, support 2.4 linux scheme as well. */
 285         if (cpu_online(cpunum)) {
 286                 extern void machine_halt(void); /* arch/parisc.../process.c */
 287
 288                 printk(KERN_CRIT "CPU#%d already initialized!\n", cpunum);
 289                 machine_halt();
 290         }
 291
 292         notify_cpu_starting(cpunum);
 293
 294         set_cpu_online(cpunum, true);
 295
 296         /* Initialise the idle task for this CPU */
 297         mmgrab(&init_mm);
 298         current->active_mm = &init_mm;
 299         BUG_ON(current->mm);
 300         enter_lazy_tlb(&init_mm, current);
 301
 302         init_IRQ();   /* make sure no IRQs are enabled or pending */
 303         start_cpu_itimer();
 304 }
 305
 306
 307 /*
 308  * Slaves start using C here. Indirectly called from smp_slave_stext.
 309  * Do what start_kernel() and main() do for boot strap processor (aka monarch)
 310  */
 311 void smp_callin(unsigned long pdce_proc)
 312 {
 313         int slave_id = cpu_now_booting;
 314
 315 #ifdef CONFIG_64BIT
 316         WARN_ON(((unsigned long)(PAGE0->mem_pdc_hi) << 32
 317                         | PAGE0->mem_pdc) != pdce_proc);
 318 #endif
 319
 320         smp_cpu_init(slave_id);
 321
 322         flush_cache_all_local(); /* start with known state */
 323         flush_tlb_all_local(NULL);
 324
 325         local_irq_enable();  /* Interrupts have been off until now */
 326
 327         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 328
 329         /* NOTREACHED */
 330         panic("smp_callin() AAAAaaaaahhhh....\n");
 331 }
 332
 333 /*
 334  * Bring one cpu online.
 335  */
 336 static int smp_boot_one_cpu(int cpuid, struct task_struct *idle)
 337 {
 338         const struct cpuinfo_parisc *p = &per_cpu(cpu_data, cpuid);
 339         long timeout;
 340
 341 #ifdef CONFIG_HOTPLUG_CPU
 342         int i;
 343
 344         /* reset irq statistics for this CPU */
 345         memset(&per_cpu(irq_stat, cpuid), 0, sizeof(irq_cpustat_t));
 346         for (i = 0; i < NR_IRQS; i++) {
 347                 struct irq_desc *desc = irq_to_desc(i);
 348
 349                 if (desc && desc->kstat_irqs)
 350                         *per_cpu_ptr(desc->kstat_irqs, cpuid) = 0;
 351         }
 352 #endif
 353
 354         /* wait until last booting CPU has started. */
 355         while (cpu_now_booting)
 356                 ;
 357
 358         /* Let _start know what logical CPU we're booting
 359         ** (offset into init_tasks[],cpu_data[])
 360         */
 361         cpu_now_booting = cpuid;
 362
 363         /*
 364         ** boot strap code needs to know the task address since
 365         ** it also contains the process stack.
 366         */
 367         smp_init_current_idle_task = idle ;
 368         mb();
 369
 370         printk(KERN_INFO "Releasing cpu %d now, hpa=%lx\n", cpuid, p->hpa);
 371
 372         /*
 373         ** This gets PDC to release the CPU from a very tight loop.
 374         **
 375         ** From the PA-RISC 2.0 Firmware Architecture Reference Specification:
 376         ** "The MEM_RENDEZ vector specifies the location of OS_RENDEZ which
 377         ** is executed after receiving the rendezvous signal (an interrupt to
 378         ** EIR{0}). MEM_RENDEZ is valid only when it is nonzero and the
 379         ** contents of memory are valid."
 380         */
 381         gsc_writel(TIMER_IRQ - CPU_IRQ_BASE, p->hpa);
 382         mb();
 383
 384         /*
 385          * OK, wait a bit for that CPU to finish staggering about.
 386          * Slave will set a bit when it reaches smp_cpu_init().
 387          * Once the "monarch CPU" sees the bit change, it can move on.
 388          */
 389         for (timeout = 0; timeout < 10000; timeout++) {
 390                 if(cpu_online(cpuid)) {
 391                         /* Which implies Slave has started up */
 392                         cpu_now_booting = 0;
 393                         goto alive ;
 394                 }
 395                 udelay(100);
 396                 barrier();
 397         }
 398         printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
 399         return -1;
 400
 401 alive:
 402         /* Remember the Slave data */
 403         smp_debug(100, KERN_DEBUG "SMP: CPU:%d came alive after %ld _us\n",
 404                 cpuid, timeout * 100);
 405         return 0;
 406 }
 407
 408 void __init smp_prepare_boot_cpu(void)
 409 {
 410         int bootstrap_processor = per_cpu(cpu_data, 0).cpuid;
 411
 412         /* Setup BSP mappings */
 413         printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor);
 414
 415         set_cpu_online(bootstrap_processor, true);
 416         set_cpu_present(bootstrap_processor, true);
 417 }
 418
 419
 420
 421 /*
 422 ** inventory.c:do_inventory() hasn't yet been run and thus we
 423 ** don't 'discover' the additional CPUs until later.
 424 */
 425 void __init smp_prepare_cpus(unsigned int max_cpus)
 426 {
 427         int cpu;
 428
 429         for_each_possible_cpu(cpu)
 430                 spin_lock_init(&per_cpu(ipi_lock, cpu));
 431
 432         init_cpu_present(cpumask_of(0));
 433 }
 434
 435
 436 void __init smp_cpus_done(unsigned int cpu_max)
 437 {
 438 }
 439
 440
 441 int __cpu_up(unsigned int cpu, struct task_struct *tidle)
 442 {
 443         if (cpu_online(cpu))
 444                 return 0;
 445
 446         if (num_online_cpus() < nr_cpu_ids &&
 447                 num_online_cpus() < setup_max_cpus &&
 448                 smp_boot_one_cpu(cpu, tidle))
 449                 return -EIO;
 450
 451         return cpu_online(cpu) ? 0 : -EIO;
 452 }
 453
 454 /*
 455  * __cpu_disable runs on the processor to be shutdown.
 456  */
 457 int __cpu_disable(void)
 458 {
 459 #ifdef CONFIG_HOTPLUG_CPU
 460         unsigned int cpu = smp_processor_id();
 461
 462         remove_cpu_topology(cpu);
 463
 464         /*
 465          * Take this CPU offline.  Once we clear this, we can't return,
 466          * and we must not schedule until we're ready to give up the cpu.
 467          */
 468         set_cpu_online(cpu, false);
 469
 470         /* Find a new timesync master */
 471         if (cpu == time_keeper_id) {
 472                 time_keeper_id = cpumask_first(cpu_online_mask);
 473                 pr_info("CPU %d is now promoted to time-keeper master\n", time_keeper_id);
 474         }
 475
 476         disable_percpu_irq(IPI_IRQ);
 477
 478         irq_migrate_all_off_this_cpu();
 479
 480         flush_cache_all_local();
 481         flush_tlb_all_local(NULL);
 482
 483         /* disable all irqs, including timer irq */
 484         local_irq_disable();
 485
 486         /* wait for next timer irq ... */
 487         mdelay(1000/HZ+100);
 488
 489         /* ... and then clear all pending external irqs */
 490         set_eiem(0);
 491         mtctl(~0UL, CR_EIRR);
 492         mfctl(CR_EIRR);
 493         mtctl(0, CR_EIRR);
 494 #endif
 495         return 0;
 496 }
 497
 498 /*
 499  * called on the thread which is asking for a CPU to be shutdown -
 500  * waits until shutdown has completed, or it is timed out.
 501  */
 502 void __cpu_die(unsigned int cpu)
 503 {
 504         pdc_cpu_rendezvous_lock();
 505
 506         if (!cpu_wait_death(cpu, 5)) {
 507                 pr_crit("CPU%u: cpu didn't die\n", cpu);
 508                 return;
 509         }
 510         pr_info("CPU%u: is shutting down\n", cpu);
 511
 512         /* set task's state to interruptible sleep */
 513         set_current_state(TASK_INTERRUPTIBLE);
 514         schedule_timeout((IS_ENABLED(CONFIG_64BIT) ? 8:2) * HZ);
 515
 516         pdc_cpu_rendezvous_unlock();
 517 }