arch/xtensa/kernel/smp.c

   1 /*
   2  * Xtensa SMP support functions.
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 2008 - 2013 Tensilica Inc.
   9  *
  10  * Chris Zankel <chris@zankel.net>
  11  * Joe Taylor <joe@tensilica.com>
  12  * Pete Delaney <piet@tensilica.com
  13  */
  14
  15 #include <linux/cpu.h>
  16 #include <linux/cpumask.h>
  17 #include <linux/delay.h>
  18 #include <linux/init.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/irqdomain.h>
  21 #include <linux/irq.h>
  22 #include <linux/kdebug.h>
  23 #include <linux/module.h>
  24 #include <linux/sched/mm.h>
  25 #include <linux/sched/hotplug.h>
  26 #include <linux/sched/task_stack.h>
  27 #include <linux/reboot.h>
  28 #include <linux/seq_file.h>
  29 #include <linux/smp.h>
  30 #include <linux/thread_info.h>
  31
  32 #include <asm/cacheflush.h>
  33 #include <asm/coprocessor.h>
  34 #include <asm/kdebug.h>
  35 #include <asm/mmu_context.h>
  36 #include <asm/mxregs.h>
  37 #include <asm/platform.h>
  38 #include <asm/tlbflush.h>
  39 #include <asm/traps.h>
  40
  41 #ifdef CONFIG_SMP
  42 # if XCHAL_HAVE_S32C1I == 0
  43 #  error "The S32C1I option is required for SMP."
  44 # endif
  45 #endif
  46
  47 static void system_invalidate_dcache_range(unsigned long start,
  48                 unsigned long size);
  49 static void system_flush_invalidate_dcache_range(unsigned long start,
  50                 unsigned long size);
  51
  52 /* IPI (Inter Process Interrupt) */
  53
  54 #define IPI_IRQ 0
  55
  56 static irqreturn_t ipi_interrupt(int irq, void *dev_id);
  57
  58 void ipi_init(void)
  59 {
  60         unsigned irq = irq_create_mapping(NULL, IPI_IRQ);
  61         if (request_irq(irq, ipi_interrupt, IRQF_PERCPU, "ipi", NULL))
  62                 pr_err("Failed to request irq %u (ipi)\n", irq);
  63 }
  64
  65 static inline unsigned int get_core_count(void)
  66 {
  67         /* Bits 18..21 of SYSCFGID contain the core count minus 1. */
  68         unsigned int syscfgid = get_er(SYSCFGID);
  69         return ((syscfgid >> 18) & 0xf) + 1;
  70 }
  71
  72 static inline int get_core_id(void)
  73 {
  74         /* Bits 0...18 of SYSCFGID contain the core id  */
  75         unsigned int core_id = get_er(SYSCFGID);
  76         return core_id & 0x3fff;
  77 }
  78
  79 void __init smp_prepare_cpus(unsigned int max_cpus)
  80 {
  81         unsigned i;
  82
  83         for_each_possible_cpu(i)
  84                 set_cpu_present(i, true);
  85 }
  86
  87 void __init smp_init_cpus(void)
  88 {
  89         unsigned i;
  90         unsigned int ncpus = get_core_count();
  91         unsigned int core_id = get_core_id();
  92
  93         pr_info("%s: Core Count = %d\n", __func__, ncpus);
  94         pr_info("%s: Core Id = %d\n", __func__, core_id);
  95
  96         if (ncpus > NR_CPUS) {
  97                 ncpus = NR_CPUS;
  98                 pr_info("%s: limiting core count by %d\n", __func__, ncpus);
  99         }
 100
 101         for (i = 0; i < ncpus; ++i)
 102                 set_cpu_possible(i, true);
 103 }
 104
 105 void __init smp_prepare_boot_cpu(void)
 106 {
 107         unsigned int cpu = smp_processor_id();
 108         BUG_ON(cpu != 0);
 109         cpu_asid_cache(cpu) = ASID_USER_FIRST;
 110 }
 111
 112 void __init smp_cpus_done(unsigned int max_cpus)
 113 {
 114 }
 115
 116 static int boot_secondary_processors = 1; /* Set with xt-gdb via .xt-gdb */
 117 static DECLARE_COMPLETION(cpu_running);
 118
 119 void secondary_start_kernel(void)
 120 {
 121         struct mm_struct *mm = &init_mm;
 122         unsigned int cpu = smp_processor_id();
 123
 124         init_mmu();
 125
 126 #ifdef CONFIG_DEBUG_MISC
 127         if (boot_secondary_processors == 0) {
 128                 pr_debug("%s: boot_secondary_processors:%d; Hanging cpu:%d\n",
 129                         __func__, boot_secondary_processors, cpu);
 130                 for (;;)
 131                         __asm__ __volatile__ ("waiti " __stringify(LOCKLEVEL));
 132         }
 133
 134         pr_debug("%s: boot_secondary_processors:%d; Booting cpu:%d\n",
 135                 __func__, boot_secondary_processors, cpu);
 136 #endif
 137         /* Init EXCSAVE1 */
 138
 139         secondary_trap_init();
 140
 141         /* All kernel threads share the same mm context. */
 142
 143         mmget(mm);
 144         mmgrab(mm);
 145         current->active_mm = mm;
 146         cpumask_set_cpu(cpu, mm_cpumask(mm));
 147         enter_lazy_tlb(mm, current);
 148
 149         trace_hardirqs_off();
 150
 151         calibrate_delay();
 152
 153         notify_cpu_starting(cpu);
 154
 155         secondary_init_irq();
 156         local_timer_setup(cpu);
 157
 158         set_cpu_online(cpu, true);
 159
 160         local_irq_enable();
 161
 162         complete(&cpu_running);
 163
 164         cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
 165 }
 166
 167 static void mx_cpu_start(void *p)
 168 {
 169         unsigned cpu = (unsigned)p;
 170         unsigned long run_stall_mask = get_er(MPSCORE);
 171
 172         set_er(run_stall_mask & ~(1u << cpu), MPSCORE);
 173         pr_debug("%s: cpu: %d, run_stall_mask: %lx ---> %lx\n",
 174                         __func__, cpu, run_stall_mask, get_er(MPSCORE));
 175 }
 176
 177 static void mx_cpu_stop(void *p)
 178 {
 179         unsigned cpu = (unsigned)p;
 180         unsigned long run_stall_mask = get_er(MPSCORE);
 181
 182         set_er(run_stall_mask | (1u << cpu), MPSCORE);
 183         pr_debug("%s: cpu: %d, run_stall_mask: %lx ---> %lx\n",
 184                         __func__, cpu, run_stall_mask, get_er(MPSCORE));
 185 }
 186
 187 #ifdef CONFIG_HOTPLUG_CPU
 188 unsigned long cpu_start_id __cacheline_aligned;
 189 #endif
 190 unsigned long cpu_start_ccount;
 191
 192 static int boot_secondary(unsigned int cpu, struct task_struct *ts)
 193 {
 194         unsigned long timeout = jiffies + msecs_to_jiffies(1000);
 195         unsigned long ccount;
 196         int i;
 197
 198 #ifdef CONFIG_HOTPLUG_CPU
 199         WRITE_ONCE(cpu_start_id, cpu);
 200         /* Pairs with the third memw in the cpu_restart */
 201         mb();
 202         system_flush_invalidate_dcache_range((unsigned long)&cpu_start_id,
 203                                              sizeof(cpu_start_id));
 204 #endif
 205         smp_call_function_single(0, mx_cpu_start, (void *)cpu, 1);
 206
 207         for (i = 0; i < 2; ++i) {
 208                 do
 209                         ccount = get_ccount();
 210                 while (!ccount);
 211
 212                 WRITE_ONCE(cpu_start_ccount, ccount);
 213
 214                 do {
 215                         /*
 216                          * Pairs with the first two memws in the
 217                          * .Lboot_secondary.
 218                          */
 219                         mb();
 220                         ccount = READ_ONCE(cpu_start_ccount);
 221                 } while (ccount && time_before(jiffies, timeout));
 222
 223                 if (ccount) {
 224                         smp_call_function_single(0, mx_cpu_stop,
 225                                                  (void *)cpu, 1);
 226                         WRITE_ONCE(cpu_start_ccount, 0);
 227                         return -EIO;
 228                 }
 229         }
 230         return 0;
 231 }
 232
 233 int __cpu_up(unsigned int cpu, struct task_struct *idle)
 234 {
 235         int ret = 0;
 236
 237         if (cpu_asid_cache(cpu) == 0)
 238                 cpu_asid_cache(cpu) = ASID_USER_FIRST;
 239
 240         start_info.stack = (unsigned long)task_pt_regs(idle);
 241         wmb();
 242
 243         pr_debug("%s: Calling wakeup_secondary(cpu:%d, idle:%p, sp: %08lx)\n",
 244                         __func__, cpu, idle, start_info.stack);
 245
 246         init_completion(&cpu_running);
 247         ret = boot_secondary(cpu, idle);
 248         if (ret == 0) {
 249                 wait_for_completion_timeout(&cpu_running,
 250                                 msecs_to_jiffies(1000));
 251                 if (!cpu_online(cpu))
 252                         ret = -EIO;
 253         }
 254
 255         if (ret)
 256                 pr_err("CPU %u failed to boot\n", cpu);
 257
 258         return ret;
 259 }
 260
 261 #ifdef CONFIG_HOTPLUG_CPU
 262
 263 /*
 264  * __cpu_disable runs on the processor to be shutdown.
 265  */
 266 int __cpu_disable(void)
 267 {
 268         unsigned int cpu = smp_processor_id();
 269
 270         /*
 271          * Take this CPU offline.  Once we clear this, we can't return,
 272          * and we must not schedule until we're ready to give up the cpu.
 273          */
 274         set_cpu_online(cpu, false);
 275
 276 #if XTENSA_HAVE_COPROCESSORS
 277         /*
 278          * Flush coprocessor contexts that are active on the current CPU.
 279          */
 280         local_coprocessors_flush_release_all();
 281 #endif
 282         /*
 283          * OK - migrate IRQs away from this CPU
 284          */
 285         migrate_irqs();
 286
 287         /*
 288          * Flush user cache and TLB mappings, and then remove this CPU
 289          * from the vm mask set of all processes.
 290          */
 291         local_flush_cache_all();
 292         local_flush_tlb_all();
 293         invalidate_page_directory();
 294
 295         clear_tasks_mm_cpumask(cpu);
 296
 297         return 0;
 298 }
 299
 300 static void platform_cpu_kill(unsigned int cpu)
 301 {
 302         smp_call_function_single(0, mx_cpu_stop, (void *)cpu, true);
 303 }
 304
 305 /*
 306  * called on the thread which is asking for a CPU to be shutdown -
 307  * waits until shutdown has completed, or it is timed out.
 308  */
 309 void __cpu_die(unsigned int cpu)
 310 {
 311         unsigned long timeout = jiffies + msecs_to_jiffies(1000);
 312         while (time_before(jiffies, timeout)) {
 313                 system_invalidate_dcache_range((unsigned long)&cpu_start_id,
 314                                                sizeof(cpu_start_id));
 315                 /* Pairs with the second memw in the cpu_restart */
 316                 mb();
 317                 if (READ_ONCE(cpu_start_id) == -cpu) {
 318                         platform_cpu_kill(cpu);
 319                         return;
 320                 }
 321         }
 322         pr_err("CPU%u: unable to kill\n", cpu);
 323 }
 324
 325 void arch_cpu_idle_dead(void)
 326 {
 327         cpu_die();
 328 }
 329 /*
 330  * Called from the idle thread for the CPU which has been shutdown.
 331  *
 332  * Note that we disable IRQs here, but do not re-enable them
 333  * before returning to the caller. This is also the behaviour
 334  * of the other hotplug-cpu capable cores, so presumably coming
 335  * out of idle fixes this.
 336  */
 337 void __ref cpu_die(void)
 338 {
 339         idle_task_exit();
 340         local_irq_disable();
 341         __asm__ __volatile__(
 342                         "       movi    a2, cpu_restart\n"
 343                         "       jx      a2\n");
 344 }
 345
 346 #endif /* CONFIG_HOTPLUG_CPU */
 347
 348 enum ipi_msg_type {
 349         IPI_RESCHEDULE = 0,
 350         IPI_CALL_FUNC,
 351         IPI_CPU_STOP,
 352         IPI_MAX
 353 };
 354
 355 static const struct {
 356         const char *short_text;
 357         const char *long_text;
 358 } ipi_text[] = {
 359         { .short_text = "RES", .long_text = "Rescheduling interrupts" },
 360         { .short_text = "CAL", .long_text = "Function call interrupts" },
 361         { .short_text = "DIE", .long_text = "CPU shutdown interrupts" },
 362 };
 363
 364 struct ipi_data {
 365         unsigned long ipi_count[IPI_MAX];
 366 };
 367
 368 static DEFINE_PER_CPU(struct ipi_data, ipi_data);
 369
 370 static void send_ipi_message(const struct cpumask *callmask,
 371                 enum ipi_msg_type msg_id)
 372 {
 373         int index;
 374         unsigned long mask = 0;
 375
 376         for_each_cpu(index, callmask)
 377                 mask |= 1 << index;
 378
 379         set_er(mask, MIPISET(msg_id));
 380 }
 381
 382 void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 383 {
 384         send_ipi_message(mask, IPI_CALL_FUNC);
 385 }
 386
 387 void arch_send_call_function_single_ipi(int cpu)
 388 {
 389         send_ipi_message(cpumask_of(cpu), IPI_CALL_FUNC);
 390 }
 391
 392 void smp_send_reschedule(int cpu)
 393 {
 394         send_ipi_message(cpumask_of(cpu), IPI_RESCHEDULE);
 395 }
 396
 397 void smp_send_stop(void)
 398 {
 399         struct cpumask targets;
 400
 401         cpumask_copy(&targets, cpu_online_mask);
 402         cpumask_clear_cpu(smp_processor_id(), &targets);
 403         send_ipi_message(&targets, IPI_CPU_STOP);
 404 }
 405
 406 static void ipi_cpu_stop(unsigned int cpu)
 407 {
 408         set_cpu_online(cpu, false);
 409         machine_halt();
 410 }
 411
 412 irqreturn_t ipi_interrupt(int irq, void *dev_id)
 413 {
 414         unsigned int cpu = smp_processor_id();
 415         struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
 416
 417         for (;;) {
 418                 unsigned int msg;
 419
 420                 msg = get_er(MIPICAUSE(cpu));
 421                 set_er(msg, MIPICAUSE(cpu));
 422
 423                 if (!msg)
 424                         break;
 425
 426                 if (msg & (1 << IPI_CALL_FUNC)) {
 427                         ++ipi->ipi_count[IPI_CALL_FUNC];
 428                         generic_smp_call_function_interrupt();
 429                 }
 430
 431                 if (msg & (1 << IPI_RESCHEDULE)) {
 432                         ++ipi->ipi_count[IPI_RESCHEDULE];
 433                         scheduler_ipi();
 434                 }
 435
 436                 if (msg & (1 << IPI_CPU_STOP)) {
 437                         ++ipi->ipi_count[IPI_CPU_STOP];
 438                         ipi_cpu_stop(cpu);
 439                 }
 440         }
 441
 442         return IRQ_HANDLED;
 443 }
 444
 445 void show_ipi_list(struct seq_file *p, int prec)
 446 {
 447         unsigned int cpu;
 448         unsigned i;
 449
 450         for (i = 0; i < IPI_MAX; ++i) {
 451                 seq_printf(p, "%*s:", prec, ipi_text[i].short_text);
 452                 for_each_online_cpu(cpu)
 453                         seq_printf(p, " %10lu",
 454                                         per_cpu(ipi_data, cpu).ipi_count[i]);
 455                 seq_printf(p, "   %s\n", ipi_text[i].long_text);
 456         }
 457 }
 458
 459 int setup_profiling_timer(unsigned int multiplier)
 460 {
 461         pr_debug("setup_profiling_timer %d\n", multiplier);
 462         return 0;
 463 }
 464
 465 /* TLB flush functions */
 466
 467 struct flush_data {
 468         struct vm_area_struct *vma;
 469         unsigned long addr1;
 470         unsigned long addr2;
 471 };
 472
 473 static void ipi_flush_tlb_all(void *arg)
 474 {
 475         local_flush_tlb_all();
 476 }
 477
 478 void flush_tlb_all(void)
 479 {
 480         on_each_cpu(ipi_flush_tlb_all, NULL, 1);
 481 }
 482
 483 static void ipi_flush_tlb_mm(void *arg)
 484 {
 485         local_flush_tlb_mm(arg);
 486 }
 487
 488 void flush_tlb_mm(struct mm_struct *mm)
 489 {
 490         on_each_cpu(ipi_flush_tlb_mm, mm, 1);
 491 }
 492
 493 static void ipi_flush_tlb_page(void *arg)
 494 {
 495         struct flush_data *fd = arg;
 496         local_flush_tlb_page(fd->vma, fd->addr1);
 497 }
 498
 499 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 500 {
 501         struct flush_data fd = {
 502                 .vma = vma,
 503                 .addr1 = addr,
 504         };
 505         on_each_cpu(ipi_flush_tlb_page, &fd, 1);
 506 }
 507
 508 static void ipi_flush_tlb_range(void *arg)
 509 {
 510         struct flush_data *fd = arg;
 511         local_flush_tlb_range(fd->vma, fd->addr1, fd->addr2);
 512 }
 513
 514 void flush_tlb_range(struct vm_area_struct *vma,
 515                      unsigned long start, unsigned long end)
 516 {
 517         struct flush_data fd = {
 518                 .vma = vma,
 519                 .addr1 = start,
 520                 .addr2 = end,
 521         };
 522         on_each_cpu(ipi_flush_tlb_range, &fd, 1);
 523 }
 524
 525 static void ipi_flush_tlb_kernel_range(void *arg)
 526 {
 527         struct flush_data *fd = arg;
 528         local_flush_tlb_kernel_range(fd->addr1, fd->addr2);
 529 }
 530
 531 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 532 {
 533         struct flush_data fd = {
 534                 .addr1 = start,
 535                 .addr2 = end,
 536         };
 537         on_each_cpu(ipi_flush_tlb_kernel_range, &fd, 1);
 538 }
 539
 540 /* Cache flush functions */
 541
 542 static void ipi_flush_cache_all(void *arg)
 543 {
 544         local_flush_cache_all();
 545 }
 546
 547 void flush_cache_all(void)
 548 {
 549         on_each_cpu(ipi_flush_cache_all, NULL, 1);
 550 }
 551
 552 static void ipi_flush_cache_page(void *arg)
 553 {
 554         struct flush_data *fd = arg;
 555         local_flush_cache_page(fd->vma, fd->addr1, fd->addr2);
 556 }
 557
 558 void flush_cache_page(struct vm_area_struct *vma,
 559                      unsigned long address, unsigned long pfn)
 560 {
 561         struct flush_data fd = {
 562                 .vma = vma,
 563                 .addr1 = address,
 564                 .addr2 = pfn,
 565         };
 566         on_each_cpu(ipi_flush_cache_page, &fd, 1);
 567 }
 568
 569 static void ipi_flush_cache_range(void *arg)
 570 {
 571         struct flush_data *fd = arg;
 572         local_flush_cache_range(fd->vma, fd->addr1, fd->addr2);
 573 }
 574
 575 void flush_cache_range(struct vm_area_struct *vma,
 576                      unsigned long start, unsigned long end)
 577 {
 578         struct flush_data fd = {
 579                 .vma = vma,
 580                 .addr1 = start,
 581                 .addr2 = end,
 582         };
 583         on_each_cpu(ipi_flush_cache_range, &fd, 1);
 584 }
 585
 586 static void ipi_flush_icache_range(void *arg)
 587 {
 588         struct flush_data *fd = arg;
 589         local_flush_icache_range(fd->addr1, fd->addr2);
 590 }
 591
 592 void flush_icache_range(unsigned long start, unsigned long end)
 593 {
 594         struct flush_data fd = {
 595                 .addr1 = start,
 596                 .addr2 = end,
 597         };
 598         on_each_cpu(ipi_flush_icache_range, &fd, 1);
 599 }
 600 EXPORT_SYMBOL(flush_icache_range);
 601
 602 /* ------------------------------------------------------------------------- */
 603
 604 static void ipi_invalidate_dcache_range(void *arg)
 605 {
 606         struct flush_data *fd = arg;
 607         __invalidate_dcache_range(fd->addr1, fd->addr2);
 608 }
 609
 610 static void system_invalidate_dcache_range(unsigned long start,
 611                 unsigned long size)
 612 {
 613         struct flush_data fd = {
 614                 .addr1 = start,
 615                 .addr2 = size,
 616         };
 617         on_each_cpu(ipi_invalidate_dcache_range, &fd, 1);
 618 }
 619
 620 static void ipi_flush_invalidate_dcache_range(void *arg)
 621 {
 622         struct flush_data *fd = arg;
 623         __flush_invalidate_dcache_range(fd->addr1, fd->addr2);
 624 }
 625
 626 static void system_flush_invalidate_dcache_range(unsigned long start,
 627                 unsigned long size)
 628 {
 629         struct flush_data fd = {
 630                 .addr1 = start,
 631                 .addr2 = size,
 632         };
 633         on_each_cpu(ipi_flush_invalidate_dcache_range, &fd, 1);
 634 }