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 51static 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 59volatile struct task_struct *smp_init_current_idle_task; 60 61/* track which CPU is booting */ 62static volatile int cpu_now_booting; 63 64static DEFINE_PER_CPU(spinlock_t, ipi_lock); 65 66enum 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*/ 87static void 88ipi_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*/ 106static void 107halt_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 119irqreturn_t __irq_entry 120ipi_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 196static inline void 197ipi_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 209static void 210send_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 218static inline void 219send_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 226static inline void 227send_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 240void kgdb_roundup_cpus(void) 241{ 242 send_IPI_allbutself(IPI_ENTER_KGDB); 243} 244#endif 245 246inline void 247smp_send_stop(void) { send_IPI_allbutself(IPI_CPU_STOP); } 248 249void 250arch_smp_send_reschedule(int cpu) { send_IPI_single(cpu, IPI_RESCHEDULE); } 251 252void 253smp_send_all_nop(void) 254{ 255 send_IPI_allbutself(IPI_NOP); 256} 257 258void arch_send_call_function_ipi_mask(const struct cpumask *mask) 259{ 260 send_IPI_mask(mask, IPI_CALL_FUNC); 261} 262 263void 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 */ 271static void 272smp_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 start_cpu_itimer(); 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 */ 308void 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 */ 333static 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) = 0; 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 398alive: 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 405void __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*/ 416void __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 427void __init smp_cpus_done(unsigned int cpu_max) 428{ 429} 430 431 432int __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 */ 448int __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 */ 493void __cpu_die(unsigned int cpu) 494{ 495 pdc_cpu_rendezvous_lock(); 496} 497 498void 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} 508