// SPDX-License-Identifier: GPL-2.0-only /* * linux/arch/arm/kernel/smp.c * * Copyright (C) 2002 ARM Limited, All Rights Reserved. */ #include <linux/module.h> #include <linux/delay.h> #include <linux/init.h> #include <linux/spinlock.h> #include <linux/sched/mm.h> #include <linux/sched/hotplug.h> #include <linux/sched/task_stack.h> #include <linux/interrupt.h> #include <linux/cache.h> #include <linux/profile.h> #include <linux/errno.h> #include <linux/mm.h> #include <linux/err.h> #include <linux/cpu.h> #include <linux/seq_file.h> #include <linux/irq.h> #include <linux/nmi.h> #include <linux/percpu.h> #include <linux/clockchips.h> #include <linux/completion.h> #include <linux/cpufreq.h> #include <linux/irq_work.h> #include <linux/atomic.h> #include <asm/bugs.h> #include <asm/smp.h> #include <asm/cacheflush.h> #include <asm/cpu.h> #include <asm/cputype.h> #include <asm/exception.h> #include <asm/idmap.h> #include <asm/topology.h> #include <asm/mmu_context.h> #include <asm/pgalloc.h> #include <asm/procinfo.h> #include <asm/processor.h> #include <asm/sections.h> #include <asm/tlbflush.h> #include <asm/ptrace.h> #include <asm/smp_plat.h> #include <asm/virt.h> #include <asm/mach/arch.h> #include <asm/mpu.h> #define CREATE_TRACE_POINTS #include <trace/events/ipi.h> /* * as from 2.5, kernels no longer have an init_tasks structure * so we need some other way of telling a new secondary core * where to place its SVC stack */ struct secondary_data secondary_data; enum ipi_msg_type { IPI_WAKEUP, IPI_TIMER, IPI_RESCHEDULE, IPI_CALL_FUNC, IPI_CPU_STOP, IPI_IRQ_WORK, IPI_COMPLETION, /* * CPU_BACKTRACE is special and not included in NR_IPI * or tracable with trace_ipi_* */ IPI_CPU_BACKTRACE, /* * SGI8-15 can be reserved by secure firmware, and thus may * not be usable by the kernel. Please keep the above limited * to at most 8 entries. */ }; static DECLARE_COMPLETION(cpu_running); static struct smp_operations smp_ops __ro_after_init; void __init smp_set_ops(const struct smp_operations *ops) { if (ops) smp_ops = *ops; }; static unsigned long get_arch_pgd(pgd_t *pgd) { #ifdef CONFIG_ARM_LPAE return __phys_to_pfn(virt_to_phys(pgd)); #else return virt_to_phys(pgd); #endif } #if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR) static int secondary_biglittle_prepare(unsigned int cpu) { if (!cpu_vtable[cpu]) cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL); return cpu_vtable[cpu] ? 0 : -ENOMEM; } static void secondary_biglittle_init(void) { init_proc_vtable(lookup_processor(read_cpuid_id())->proc); } #else static int secondary_biglittle_prepare(unsigned int cpu) { return 0; } static void secondary_biglittle_init(void) { } #endif int __cpu_up(unsigned int cpu, struct task_struct *idle) { int ret; if (!smp_ops.smp_boot_secondary) return -ENOSYS; ret = secondary_biglittle_prepare(cpu); if (ret) return ret; /* * We need to tell the secondary core where to find * its stack and the page tables. */ secondary_data.stack = task_stack_page(idle) + THREAD_START_SP; #ifdef CONFIG_ARM_MPU secondary_data.mpu_rgn_info = &mpu_rgn_info; #endif #ifdef CONFIG_MMU secondary_data.pgdir = virt_to_phys(idmap_pgd); secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir); #endif sync_cache_w(&secondary_data); /* * Now bring the CPU into our world. */ ret = smp_ops.smp_boot_secondary(cpu, idle); if (ret == 0) { /* * CPU was successfully started, wait for it * to come online or time out. */ wait_for_completion_timeout(&cpu_running, msecs_to_jiffies(1000)); if (!cpu_online(cpu)) { pr_crit("CPU%u: failed to come online\n", cpu); ret = -EIO; } } else { pr_err("CPU%u: failed to boot: %d\n", cpu, ret); } memset(&secondary_data, 0, sizeof(secondary_data)); return ret; } /* platform specific SMP operations */ void __init smp_init_cpus(void) { if (smp_ops.smp_init_cpus) smp_ops.smp_init_cpus(); } int platform_can_secondary_boot(void) { return !!smp_ops.smp_boot_secondary; } int platform_can_cpu_hotplug(void) { #ifdef CONFIG_HOTPLUG_CPU if (smp_ops.cpu_kill) return 1; #endif return 0; } #ifdef CONFIG_HOTPLUG_CPU static int platform_cpu_kill(unsigned int cpu) { if (smp_ops.cpu_kill) return smp_ops.cpu_kill(cpu); return 1; } static int platform_cpu_disable(unsigned int cpu) { if (smp_ops.cpu_disable) return smp_ops.cpu_disable(cpu); return 0; } int platform_can_hotplug_cpu(unsigned int cpu) { /* cpu_die must be specified to support hotplug */ if (!smp_ops.cpu_die) return 0; if (smp_ops.cpu_can_disable) return smp_ops.cpu_can_disable(cpu); /* * By default, allow disabling all CPUs except the first one, * since this is special on a lot of platforms, e.g. because * of clock tick interrupts. */ return cpu != 0; } /* * __cpu_disable runs on the processor to be shutdown. */ int __cpu_disable(void) { unsigned int cpu = smp_processor_id(); int ret; ret = platform_cpu_disable(cpu); if (ret) return ret; #ifdef CONFIG_GENERIC_ARCH_TOPOLOGY remove_cpu_topology(cpu); #endif /* * Take this CPU offline. Once we clear this, we can't return, * and we must not schedule until we're ready to give up the cpu. */ set_cpu_online(cpu, false); /* * OK - migrate IRQs away from this CPU */ irq_migrate_all_off_this_cpu(); /* * Flush user cache and TLB mappings, and then remove this CPU * from the vm mask set of all processes. * * Caches are flushed to the Level of Unification Inner Shareable * to write-back dirty lines to unified caches shared by all CPUs. */ flush_cache_louis(); local_flush_tlb_all(); return 0; } /* * called on the thread which is asking for a CPU to be shutdown - * waits until shutdown has completed, or it is timed out. */ void __cpu_die(unsigned int cpu) { if (!cpu_wait_death(cpu, 5)) { pr_err("CPU%u: cpu didn't die\n", cpu); return; } pr_debug("CPU%u: shutdown\n", cpu); clear_tasks_mm_cpumask(cpu); /* * platform_cpu_kill() is generally expected to do the powering off * and/or cutting of clocks to the dying CPU. Optionally, this may * be done by the CPU which is dying in preference to supporting * this call, but that means there is _no_ synchronisation between * the requesting CPU and the dying CPU actually losing power. */ if (!platform_cpu_kill(cpu)) pr_err("CPU%u: unable to kill\n", cpu); } /* * Called from the idle thread for the CPU which has been shutdown. * * Note that we disable IRQs here, but do not re-enable them * before returning to the caller. This is also the behaviour * of the other hotplug-cpu capable cores, so presumably coming * out of idle fixes this. */ void arch_cpu_idle_dead(void) { unsigned int cpu = smp_processor_id(); idle_task_exit(); local_irq_disable(); /* * Flush the data out of the L1 cache for this CPU. This must be * before the completion to ensure that data is safely written out * before platform_cpu_kill() gets called - which may disable * *this* CPU and power down its cache. */ flush_cache_louis(); /* * Tell __cpu_die() that this CPU is now safe to dispose of. Once * this returns, power and/or clocks can be removed at any point * from this CPU and its cache by platform_cpu_kill(). */ (void)cpu_report_death(); /* * Ensure that the cache lines associated with that completion are * written out. This covers the case where _this_ CPU is doing the * powering down, to ensure that the completion is visible to the * CPU waiting for this one. */ flush_cache_louis(); /* * The actual CPU shutdown procedure is at least platform (if not * CPU) specific. This may remove power, or it may simply spin. * * Platforms are generally expected *NOT* to return from this call, * although there are some which do because they have no way to * power down the CPU. These platforms are the _only_ reason we * have a return path which uses the fragment of assembly below. * * The return path should not be used for platforms which can * power off the CPU. */ if (smp_ops.cpu_die) smp_ops.cpu_die(cpu); pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n", cpu); /* * Do not return to the idle loop - jump back to the secondary * cpu initialisation. There's some initialisation which needs * to be repeated to undo the effects of taking the CPU offline. */ __asm__("mov sp, %0\n" " mov fp, #0\n" " b secondary_start_kernel" : : "r" (task_stack_page(current) + THREAD_SIZE - 8)); } #endif /* CONFIG_HOTPLUG_CPU */ /* * Called by both boot and secondaries to move global data into * per-processor storage. */ static void smp_store_cpu_info(unsigned int cpuid) { struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid); cpu_info->loops_per_jiffy = loops_per_jiffy; cpu_info->cpuid = read_cpuid_id(); store_cpu_topology(cpuid); check_cpu_icache_size(cpuid); } /* * This is the secondary CPU boot entry. We're using this CPUs * idle thread stack, but a set of temporary page tables. */ asmlinkage void secondary_start_kernel(void) { struct mm_struct *mm = &init_mm; unsigned int cpu; secondary_biglittle_init(); /* * The identity mapping is uncached (strongly ordered), so * switch away from it before attempting any exclusive accesses. */ cpu_switch_mm(mm->pgd, mm); local_flush_bp_all(); enter_lazy_tlb(mm, current); local_flush_tlb_all(); /* * All kernel threads share the same mm context; grab a * reference and switch to it. */ cpu = smp_processor_id(); mmgrab(mm); current->active_mm = mm; cpumask_set_cpu(cpu, mm_cpumask(mm)); cpu_init(); #ifndef CONFIG_MMU setup_vectors_base(); #endif pr_debug("CPU%u: Booted secondary processor\n", cpu); preempt_disable(); trace_hardirqs_off(); /* * Give the platform a chance to do its own initialisation. */ if (smp_ops.smp_secondary_init) smp_ops.smp_secondary_init(cpu); notify_cpu_starting(cpu); calibrate_delay(); smp_store_cpu_info(cpu); /* * OK, now it's safe to let the boot CPU continue. Wait for * the CPU migration code to notice that the CPU is online * before we continue - which happens after __cpu_up returns. */ set_cpu_online(cpu, true); check_other_bugs(); complete(&cpu_running); local_irq_enable(); local_fiq_enable(); local_abt_enable(); /* * OK, it's off to the idle thread for us */ cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); } void __init smp_cpus_done(unsigned int max_cpus) { int cpu; unsigned long bogosum = 0; for_each_online_cpu(cpu) bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy; printk(KERN_INFO "SMP: Total of %d processors activated " "(%lu.%02lu BogoMIPS).\n", num_online_cpus(), bogosum / (500000/HZ), (bogosum / (5000/HZ)) % 100); hyp_mode_check(); } void __init smp_prepare_boot_cpu(void) { set_my_cpu_offset(per_cpu_offset(smp_processor_id())); } void __init smp_prepare_cpus(unsigned int max_cpus) { unsigned int ncores = num_possible_cpus(); init_cpu_topology(); smp_store_cpu_info(smp_processor_id()); /* * are we trying to boot more cores than exist? */ if (max_cpus > ncores) max_cpus = ncores; if (ncores > 1 && max_cpus) { /* * Initialise the present map, which describes the set of CPUs * actually populated at the present time. A platform should * re-initialize the map in the platforms smp_prepare_cpus() * if present != possible (e.g. physical hotplug). */ init_cpu_present(cpu_possible_mask); /* * Initialise the SCU if there are more than one CPU * and let them know where to start. */ if (smp_ops.smp_prepare_cpus) smp_ops.smp_prepare_cpus(max_cpus); } } static void (*__smp_cross_call)(const struct cpumask *, unsigned int); void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int)) { if (!__smp_cross_call) __smp_cross_call = fn; } static const char *ipi_types[NR_IPI] __tracepoint_string = { #define S(x,s) [x] = s S(IPI_WAKEUP, "CPU wakeup interrupts"), S(IPI_TIMER, "Timer broadcast interrupts"), S(IPI_RESCHEDULE, "Rescheduling interrupts"), S(IPI_CALL_FUNC, "Function call interrupts"), S(IPI_CPU_STOP, "CPU stop interrupts"), S(IPI_IRQ_WORK, "IRQ work interrupts"), S(IPI_COMPLETION, "completion interrupts"), }; static void smp_cross_call(const struct cpumask *target, unsigned int ipinr) { trace_ipi_raise_rcuidle(target, ipi_types[ipinr]); __smp_cross_call(target, ipinr); } void show_ipi_list(struct seq_file *p, int prec) { unsigned int cpu, i; for (i = 0; i < NR_IPI; i++) { seq_printf(p, "%*s%u: ", prec - 1, "IPI", i); for_each_online_cpu(cpu) seq_printf(p, "%10u ", __get_irq_stat(cpu, ipi_irqs[i])); seq_printf(p, " %s\n", ipi_types[i]); } } u64 smp_irq_stat_cpu(unsigned int cpu) { u64 sum = 0; int i; for (i = 0; i < NR_IPI; i++) sum += __get_irq_stat(cpu, ipi_irqs[i]); return sum; } void arch_send_call_function_ipi_mask(const struct cpumask *mask) { smp_cross_call(mask, IPI_CALL_FUNC); } void arch_send_wakeup_ipi_mask(const struct cpumask *mask) { smp_cross_call(mask, IPI_WAKEUP); } void arch_send_call_function_single_ipi(int cpu) { smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC); } #ifdef CONFIG_IRQ_WORK void arch_irq_work_raise(void) { if (arch_irq_work_has_interrupt()) smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK); } #endif #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST void tick_broadcast(const struct cpumask *mask) { smp_cross_call(mask, IPI_TIMER); } #endif static DEFINE_RAW_SPINLOCK(stop_lock); /* * ipi_cpu_stop - handle IPI from smp_send_stop() */ static void ipi_cpu_stop(unsigned int cpu) { if (system_state <= SYSTEM_RUNNING) { raw_spin_lock(&stop_lock); pr_crit("CPU%u: stopping\n", cpu); dump_stack(); raw_spin_unlock(&stop_lock); } set_cpu_online(cpu, false); local_fiq_disable(); local_irq_disable(); while (1) { cpu_relax(); wfe(); } } static DEFINE_PER_CPU(struct completion *, cpu_completion); int register_ipi_completion(struct completion *completion, int cpu) { per_cpu(cpu_completion, cpu) = completion; return IPI_COMPLETION; } static void ipi_complete(unsigned int cpu) { complete(per_cpu(cpu_completion, cpu)); } /* * Main handler for inter-processor interrupts */ asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs) { handle_IPI(ipinr, regs); } void handle_IPI(int ipinr, struct pt_regs *regs) { unsigned int cpu = smp_processor_id(); struct pt_regs *old_regs = set_irq_regs(regs); if ((unsigned)ipinr < NR_IPI) { trace_ipi_entry_rcuidle(ipi_types[ipinr]); __inc_irq_stat(cpu, ipi_irqs[ipinr]); } switch (ipinr) { case IPI_WAKEUP: break; #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST case IPI_TIMER: irq_enter(); tick_receive_broadcast(); irq_exit(); break; #endif case IPI_RESCHEDULE: scheduler_ipi(); break; case IPI_CALL_FUNC: irq_enter(); generic_smp_call_function_interrupt(); irq_exit(); break; case IPI_CPU_STOP: irq_enter(); ipi_cpu_stop(cpu); irq_exit(); break; #ifdef CONFIG_IRQ_WORK case IPI_IRQ_WORK: irq_enter(); irq_work_run(); irq_exit(); break; #endif case IPI_COMPLETION: irq_enter(); ipi_complete(cpu); irq_exit(); break; case IPI_CPU_BACKTRACE: printk_nmi_enter(); irq_enter(); nmi_cpu_backtrace(regs); irq_exit(); printk_nmi_exit(); break; default: pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr); break; } if ((unsigned)ipinr < NR_IPI) trace_ipi_exit_rcuidle(ipi_types[ipinr]); set_irq_regs(old_regs); } void smp_send_reschedule(int cpu) { smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE); } void smp_send_stop(void) { unsigned long timeout; struct cpumask mask; cpumask_copy(&mask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &mask); if (!cpumask_empty(&mask)) smp_cross_call(&mask, IPI_CPU_STOP); /* Wait up to one second for other CPUs to stop */ timeout = USEC_PER_SEC; while (num_online_cpus() > 1 && timeout--) udelay(1); if (num_online_cpus() > 1) pr_warn("SMP: failed to stop secondary CPUs\n"); } /* In case panic() and panic() called at the same time on CPU1 and CPU2, * and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop() * CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online, * kdump fails. So split out the panic_smp_self_stop() and add * set_cpu_online(smp_processor_id(), false). */ void panic_smp_self_stop(void) { pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n", smp_processor_id()); set_cpu_online(smp_processor_id(), false); while (1) cpu_relax(); } /* * not supported here */ int setup_profiling_timer(unsigned int multiplier) { return -EINVAL; } #ifdef CONFIG_CPU_FREQ static DEFINE_PER_CPU(unsigned long, l_p_j_ref); static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq); static unsigned long global_l_p_j_ref; static unsigned long global_l_p_j_ref_freq; static int cpufreq_callback(struct notifier_block *nb, unsigned long val, void *data) { struct cpufreq_freqs *freq = data; struct cpumask *cpus = freq->policy->cpus; int cpu, first = cpumask_first(cpus); unsigned int lpj; if (freq->flags & CPUFREQ_CONST_LOOPS) return NOTIFY_OK; if (!per_cpu(l_p_j_ref, first)) { for_each_cpu(cpu, cpus) { per_cpu(l_p_j_ref, cpu) = per_cpu(cpu_data, cpu).loops_per_jiffy; per_cpu(l_p_j_ref_freq, cpu) = freq->old; } if (!global_l_p_j_ref) { global_l_p_j_ref = loops_per_jiffy; global_l_p_j_ref_freq = freq->old; } } if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) || (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) { loops_per_jiffy = cpufreq_scale(global_l_p_j_ref, global_l_p_j_ref_freq, freq->new); lpj = cpufreq_scale(per_cpu(l_p_j_ref, first), per_cpu(l_p_j_ref_freq, first), freq->new); for_each_cpu(cpu, cpus) per_cpu(cpu_data, cpu).loops_per_jiffy = lpj; } return NOTIFY_OK; } static struct notifier_block cpufreq_notifier = { .notifier_call = cpufreq_callback, }; static int __init register_cpufreq_notifier(void) { return cpufreq_register_notifier(&cpufreq_notifier, CPUFREQ_TRANSITION_NOTIFIER); } core_initcall(register_cpufreq_notifier); #endif static void raise_nmi(cpumask_t *mask) { __smp_cross_call(mask, IPI_CPU_BACKTRACE); } void arch_trigger_cpumask_backtrace(const cpumask_t *mask, bool exclude_self) { nmi_trigger_cpumask_backtrace(mask, exclude_self, raise_nmi); }