// SPDX-License-Identifier: GPL-2.0-only /* * SMP initialisation and IPI support * Based on arch/arm/kernel/smp.c * * Copyright (C) 2012 ARM Ltd. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * 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; /* Number of CPUs which aren't online, but looping in kernel text. */ static int cpus_stuck_in_kernel; enum ipi_msg_type { IPI_RESCHEDULE, IPI_CALL_FUNC, IPI_CPU_STOP, IPI_CPU_STOP_NMI, IPI_TIMER, IPI_IRQ_WORK, NR_IPI, /* * Any enum >= NR_IPI and < MAX_IPI is special and not tracable * with trace_ipi_* */ IPI_CPU_BACKTRACE = NR_IPI, IPI_KGDB_ROUNDUP, MAX_IPI }; static int ipi_irq_base __ro_after_init; static int nr_ipi __ro_after_init = NR_IPI; static struct irq_desc *ipi_desc[MAX_IPI] __ro_after_init; static bool crash_stop; static void ipi_setup(int cpu); #ifdef CONFIG_HOTPLUG_CPU static void ipi_teardown(int cpu); static int op_cpu_kill(unsigned int cpu); #else static inline int op_cpu_kill(unsigned int cpu) { return -ENOSYS; } #endif /* * Boot a secondary CPU, and assign it the specified idle task. * This also gives us the initial stack to use for this CPU. */ static int boot_secondary(unsigned int cpu, struct task_struct *idle) { const struct cpu_operations *ops = get_cpu_ops(cpu); if (ops->cpu_boot) return ops->cpu_boot(cpu); return -EOPNOTSUPP; } static DECLARE_COMPLETION(cpu_running); int __cpu_up(unsigned int cpu, struct task_struct *idle) { int ret; long status; /* * We need to tell the secondary core where to find its stack and the * page tables. */ secondary_data.task = idle; update_cpu_boot_status(CPU_MMU_OFF); /* Now bring the CPU into our world */ ret = boot_secondary(cpu, idle); if (ret) { if (ret != -EPERM) pr_err("CPU%u: failed to boot: %d\n", cpu, ret); return ret; } /* * CPU was successfully started, wait for it to come online or * time out. */ wait_for_completion_timeout(&cpu_running, msecs_to_jiffies(5000)); if (cpu_online(cpu)) return 0; pr_crit("CPU%u: failed to come online\n", cpu); secondary_data.task = NULL; status = READ_ONCE(secondary_data.status); if (status == CPU_MMU_OFF) status = READ_ONCE(__early_cpu_boot_status); switch (status & CPU_BOOT_STATUS_MASK) { default: pr_err("CPU%u: failed in unknown state : 0x%lx\n", cpu, status); cpus_stuck_in_kernel++; break; case CPU_KILL_ME: if (!op_cpu_kill(cpu)) { pr_crit("CPU%u: died during early boot\n", cpu); break; } pr_crit("CPU%u: may not have shut down cleanly\n", cpu); fallthrough; case CPU_STUCK_IN_KERNEL: pr_crit("CPU%u: is stuck in kernel\n", cpu); if (status & CPU_STUCK_REASON_52_BIT_VA) pr_crit("CPU%u: does not support 52-bit VAs\n", cpu); if (status & CPU_STUCK_REASON_NO_GRAN) { pr_crit("CPU%u: does not support %luK granule\n", cpu, PAGE_SIZE / SZ_1K); } cpus_stuck_in_kernel++; break; case CPU_PANIC_KERNEL: panic("CPU%u detected unsupported configuration\n", cpu); } return -EIO; } static void init_gic_priority_masking(void) { u32 cpuflags; if (WARN_ON(!gic_enable_sre())) return; cpuflags = read_sysreg(daif); WARN_ON(!(cpuflags & PSR_I_BIT)); WARN_ON(!(cpuflags & PSR_F_BIT)); gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET); } /* * This is the secondary CPU boot entry. We're using this CPUs * idle thread stack, but a set of temporary page tables. */ asmlinkage notrace void secondary_start_kernel(void) { u64 mpidr = read_cpuid_mpidr() & MPIDR_HWID_BITMASK; struct mm_struct *mm = &init_mm; const struct cpu_operations *ops; unsigned int cpu = smp_processor_id(); /* * All kernel threads share the same mm context; grab a * reference and switch to it. */ mmgrab(mm); current->active_mm = mm; /* * TTBR0 is only used for the identity mapping at this stage. Make it * point to zero page to avoid speculatively fetching new entries. */ cpu_uninstall_idmap(); if (system_uses_irq_prio_masking()) init_gic_priority_masking(); rcutree_report_cpu_starting(cpu); trace_hardirqs_off(); /* * If the system has established the capabilities, make sure * this CPU ticks all of those. If it doesn't, the CPU will * fail to come online. */ check_local_cpu_capabilities(); ops = get_cpu_ops(cpu); if (ops->cpu_postboot) ops->cpu_postboot(); /* * Log the CPU info before it is marked online and might get read. */ cpuinfo_store_cpu(); store_cpu_topology(cpu); /* * Enable GIC and timers. */ notify_cpu_starting(cpu); ipi_setup(cpu); numa_add_cpu(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. */ pr_info("CPU%u: Booted secondary processor 0x%010lx [0x%08x]\n", cpu, (unsigned long)mpidr, read_cpuid_id()); update_cpu_boot_status(CPU_BOOT_SUCCESS); set_cpu_online(cpu, true); complete(&cpu_running); /* * Secondary CPUs enter the kernel with all DAIF exceptions masked. * * As with setup_arch() we must unmask Debug and SError exceptions, and * as the root irqchip has already been detected and initialized we can * unmask IRQ and FIQ at the same time. */ local_daif_restore(DAIF_PROCCTX); /* * OK, it's off to the idle thread for us */ cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); } #ifdef CONFIG_HOTPLUG_CPU static int op_cpu_disable(unsigned int cpu) { const struct cpu_operations *ops = get_cpu_ops(cpu); /* * If we don't have a cpu_die method, abort before we reach the point * of no return. CPU0 may not have an cpu_ops, so test for it. */ if (!ops || !ops->cpu_die) return -EOPNOTSUPP; /* * We may need to abort a hot unplug for some other mechanism-specific * reason. */ if (ops->cpu_disable) return ops->cpu_disable(cpu); return 0; } /* * __cpu_disable runs on the processor to be shutdown. */ int __cpu_disable(void) { unsigned int cpu = smp_processor_id(); int ret; ret = op_cpu_disable(cpu); if (ret) return ret; remove_cpu_topology(cpu); numa_remove_cpu(cpu); /* * 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); ipi_teardown(cpu); /* * OK - migrate IRQs away from this CPU */ irq_migrate_all_off_this_cpu(); return 0; } static int op_cpu_kill(unsigned int cpu) { const struct cpu_operations *ops = get_cpu_ops(cpu); /* * If we have no means of synchronising with the dying CPU, then assume * that it is really dead. We can only wait for an arbitrary length of * time and hope that it's dead, so let's skip the wait and just hope. */ if (!ops->cpu_kill) return 0; return ops->cpu_kill(cpu); } /* * Called on the thread which is asking for a CPU to be shutdown after the * shutdown completed. */ void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu) { int err; pr_debug("CPU%u: shutdown\n", cpu); /* * Now that the dying CPU is beyond the point of no return w.r.t. * in-kernel synchronisation, try to get the firwmare to help us to * verify that it has really left the kernel before we consider * clobbering anything it might still be using. */ err = op_cpu_kill(cpu); if (err) pr_warn("CPU%d may not have shut down cleanly: %d\n", cpu, err); } /* * Called from the idle thread for the CPU which has been shutdown. * */ void __noreturn cpu_die(void) { unsigned int cpu = smp_processor_id(); const struct cpu_operations *ops = get_cpu_ops(cpu); idle_task_exit(); local_daif_mask(); /* Tell cpuhp_bp_sync_dead() that this CPU is now safe to dispose of */ cpuhp_ap_report_dead(); /* * Actually shutdown the CPU. This must never fail. The specific hotplug * mechanism must perform all required cache maintenance to ensure that * no dirty lines are lost in the process of shutting down the CPU. */ ops->cpu_die(cpu); BUG(); } #endif static void __cpu_try_die(int cpu) { #ifdef CONFIG_HOTPLUG_CPU const struct cpu_operations *ops = get_cpu_ops(cpu); if (ops && ops->cpu_die) ops->cpu_die(cpu); #endif } /* * Kill the calling secondary CPU, early in bringup before it is turned * online. */ void __noreturn cpu_die_early(void) { int cpu = smp_processor_id(); pr_crit("CPU%d: will not boot\n", cpu); /* Mark this CPU absent */ set_cpu_present(cpu, 0); rcutree_report_cpu_dead(); if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { update_cpu_boot_status(CPU_KILL_ME); __cpu_try_die(cpu); } update_cpu_boot_status(CPU_STUCK_IN_KERNEL); cpu_park_loop(); } static void __init hyp_mode_check(void) { if (is_hyp_mode_available()) pr_info("CPU: All CPU(s) started at EL2\n"); else if (is_hyp_mode_mismatched()) WARN_TAINT(1, TAINT_CPU_OUT_OF_SPEC, "CPU: CPUs started in inconsistent modes"); else pr_info("CPU: All CPU(s) started at EL1\n"); if (IS_ENABLED(CONFIG_KVM) && !is_kernel_in_hyp_mode()) { kvm_compute_layout(); kvm_apply_hyp_relocations(); } } void __init smp_cpus_done(unsigned int max_cpus) { pr_info("SMP: Total of %d processors activated.\n", num_online_cpus()); hyp_mode_check(); setup_system_features(); setup_user_features(); mark_linear_text_alias_ro(); } void __init smp_prepare_boot_cpu(void) { /* * The runtime per-cpu areas have been allocated by * setup_per_cpu_areas(), and CPU0's boot time per-cpu area will be * freed shortly, so we must move over to the runtime per-cpu area. */ set_my_cpu_offset(per_cpu_offset(smp_processor_id())); cpuinfo_store_boot_cpu(); setup_boot_cpu_features(); /* Conditionally switch to GIC PMR for interrupt masking */ if (system_uses_irq_prio_masking()) init_gic_priority_masking(); kasan_init_hw_tags(); /* Init percpu seeds for random tags after cpus are set up. */ kasan_init_sw_tags(); } /* * Duplicate MPIDRs are a recipe for disaster. Scan all initialized * entries and check for duplicates. If any is found just ignore the * cpu. cpu_logical_map was initialized to INVALID_HWID to avoid * matching valid MPIDR values. */ static bool __init is_mpidr_duplicate(unsigned int cpu, u64 hwid) { unsigned int i; for (i = 1; (i < cpu) && (i < NR_CPUS); i++) if (cpu_logical_map(i) == hwid) return true; return false; } /* * Initialize cpu operations for a logical cpu and * set it in the possible mask on success */ static int __init smp_cpu_setup(int cpu) { const struct cpu_operations *ops; if (init_cpu_ops(cpu)) return -ENODEV; ops = get_cpu_ops(cpu); if (ops->cpu_init(cpu)) return -ENODEV; set_cpu_possible(cpu, true); return 0; } static bool bootcpu_valid __initdata; static unsigned int cpu_count = 1; int arch_register_cpu(int cpu) { acpi_handle acpi_handle = acpi_get_processor_handle(cpu); struct cpu *c = &per_cpu(cpu_devices, cpu); if (!acpi_disabled && !acpi_handle && IS_ENABLED(CONFIG_ACPI_HOTPLUG_CPU)) return -EPROBE_DEFER; #ifdef CONFIG_ACPI_HOTPLUG_CPU /* For now block anything that looks like physical CPU Hotplug */ if (invalid_logical_cpuid(cpu) || !cpu_present(cpu)) { pr_err_once("Changing CPU present bit is not supported\n"); return -ENODEV; } #endif /* * Availability of the acpi handle is sufficient to establish * that _STA has aleady been checked. No need to recheck here. */ c->hotpluggable = arch_cpu_is_hotpluggable(cpu); return register_cpu(c, cpu); } #ifdef CONFIG_ACPI_HOTPLUG_CPU void arch_unregister_cpu(int cpu) { acpi_handle acpi_handle = acpi_get_processor_handle(cpu); struct cpu *c = &per_cpu(cpu_devices, cpu); acpi_status status; unsigned long long sta; if (!acpi_handle) { pr_err_once("Removing a CPU without associated ACPI handle\n"); return; } status = acpi_evaluate_integer(acpi_handle, "_STA", NULL, &sta); if (ACPI_FAILURE(status)) return; /* For now do not allow anything that looks like physical CPU HP */ if (cpu_present(cpu) && !(sta & ACPI_STA_DEVICE_PRESENT)) { pr_err_once("Changing CPU present bit is not supported\n"); return; } unregister_cpu(c); } #endif /* CONFIG_ACPI_HOTPLUG_CPU */ #ifdef CONFIG_ACPI static struct acpi_madt_generic_interrupt cpu_madt_gicc[NR_CPUS]; struct acpi_madt_generic_interrupt *acpi_cpu_get_madt_gicc(int cpu) { return &cpu_madt_gicc[cpu]; } EXPORT_SYMBOL_GPL(acpi_cpu_get_madt_gicc); /* * acpi_map_gic_cpu_interface - parse processor MADT entry * * Carry out sanity checks on MADT processor entry and initialize * cpu_logical_map on success */ static void __init acpi_map_gic_cpu_interface(struct acpi_madt_generic_interrupt *processor) { u64 hwid = processor->arm_mpidr; if (!(processor->flags & (ACPI_MADT_ENABLED | ACPI_MADT_GICC_ONLINE_CAPABLE))) { pr_debug("skipping disabled CPU entry with 0x%llx MPIDR\n", hwid); return; } if (hwid & ~MPIDR_HWID_BITMASK || hwid == INVALID_HWID) { pr_err("skipping CPU entry with invalid MPIDR 0x%llx\n", hwid); return; } if (is_mpidr_duplicate(cpu_count, hwid)) { pr_err("duplicate CPU MPIDR 0x%llx in MADT\n", hwid); return; } /* Check if GICC structure of boot CPU is available in the MADT */ if (cpu_logical_map(0) == hwid) { if (bootcpu_valid) { pr_err("duplicate boot CPU MPIDR: 0x%llx in MADT\n", hwid); return; } bootcpu_valid = true; cpu_madt_gicc[0] = *processor; return; } if (cpu_count >= NR_CPUS) return; /* map the logical cpu id to cpu MPIDR */ set_cpu_logical_map(cpu_count, hwid); cpu_madt_gicc[cpu_count] = *processor; /* * Set-up the ACPI parking protocol cpu entries * while initializing the cpu_logical_map to * avoid parsing MADT entries multiple times for * nothing (ie a valid cpu_logical_map entry should * contain a valid parking protocol data set to * initialize the cpu if the parking protocol is * the only available enable method). */ acpi_set_mailbox_entry(cpu_count, processor); cpu_count++; } static int __init acpi_parse_gic_cpu_interface(union acpi_subtable_headers *header, const unsigned long end) { struct acpi_madt_generic_interrupt *processor; processor = (struct acpi_madt_generic_interrupt *)header; if (BAD_MADT_GICC_ENTRY(processor, end)) return -EINVAL; acpi_table_print_madt_entry(&header->common); acpi_map_gic_cpu_interface(processor); return 0; } static void __init acpi_parse_and_init_cpus(void) { int i; /* * do a walk of MADT to determine how many CPUs * we have including disabled CPUs, and get information * we need for SMP init. */ acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT, acpi_parse_gic_cpu_interface, 0); /* * In ACPI, SMP and CPU NUMA information is provided in separate * static tables, namely the MADT and the SRAT. * * Thus, it is simpler to first create the cpu logical map through * an MADT walk and then map the logical cpus to their node ids * as separate steps. */ acpi_map_cpus_to_nodes(); for (i = 0; i < nr_cpu_ids; i++) early_map_cpu_to_node(i, acpi_numa_get_nid(i)); } #else #define acpi_parse_and_init_cpus(...) do { } while (0) #endif /* * Enumerate the possible CPU set from the device tree and build the * cpu logical map array containing MPIDR values related to logical * cpus. Assumes that cpu_logical_map(0) has already been initialized. */ static void __init of_parse_and_init_cpus(void) { struct device_node *dn; for_each_of_cpu_node(dn) { u64 hwid = of_get_cpu_hwid(dn, 0); if (hwid & ~MPIDR_HWID_BITMASK) goto next; if (is_mpidr_duplicate(cpu_count, hwid)) { pr_err("%pOF: duplicate cpu reg properties in the DT\n", dn); goto next; } /* * The numbering scheme requires that the boot CPU * must be assigned logical id 0. Record it so that * the logical map built from DT is validated and can * be used. */ if (hwid == cpu_logical_map(0)) { if (bootcpu_valid) { pr_err("%pOF: duplicate boot cpu reg property in DT\n", dn); goto next; } bootcpu_valid = true; early_map_cpu_to_node(0, of_node_to_nid(dn)); /* * cpu_logical_map has already been * initialized and the boot cpu doesn't need * the enable-method so continue without * incrementing cpu. */ continue; } if (cpu_count >= NR_CPUS) goto next; pr_debug("cpu logical map 0x%llx\n", hwid); set_cpu_logical_map(cpu_count, hwid); early_map_cpu_to_node(cpu_count, of_node_to_nid(dn)); next: cpu_count++; } } /* * Enumerate the possible CPU set from the device tree or ACPI and build the * cpu logical map array containing MPIDR values related to logical * cpus. Assumes that cpu_logical_map(0) has already been initialized. */ void __init smp_init_cpus(void) { int i; if (acpi_disabled) of_parse_and_init_cpus(); else acpi_parse_and_init_cpus(); if (cpu_count > nr_cpu_ids) pr_warn("Number of cores (%d) exceeds configured maximum of %u - clipping\n", cpu_count, nr_cpu_ids); if (!bootcpu_valid) { pr_err("missing boot CPU MPIDR, not enabling secondaries\n"); return; } /* * We need to set the cpu_logical_map entries before enabling * the cpus so that cpu processor description entries (DT cpu nodes * and ACPI MADT entries) can be retrieved by matching the cpu hwid * with entries in cpu_logical_map while initializing the cpus. * If the cpu set-up fails, invalidate the cpu_logical_map entry. */ for (i = 1; i < nr_cpu_ids; i++) { if (cpu_logical_map(i) != INVALID_HWID) { if (smp_cpu_setup(i)) set_cpu_logical_map(i, INVALID_HWID); } } } void __init smp_prepare_cpus(unsigned int max_cpus) { const struct cpu_operations *ops; int err; unsigned int cpu; unsigned int this_cpu; init_cpu_topology(); this_cpu = smp_processor_id(); store_cpu_topology(this_cpu); numa_store_cpu_info(this_cpu); numa_add_cpu(this_cpu); /* * If UP is mandated by "nosmp" (which implies "maxcpus=0"), don't set * secondary CPUs present. */ if (max_cpus == 0) return; /* * Initialise the present map (which describes the set of CPUs * actually populated at the present time) and release the * secondaries from the bootloader. */ for_each_possible_cpu(cpu) { if (cpu == smp_processor_id()) continue; ops = get_cpu_ops(cpu); if (!ops) continue; err = ops->cpu_prepare(cpu); if (err) continue; set_cpu_present(cpu, true); numa_store_cpu_info(cpu); } } static const char *ipi_types[MAX_IPI] __tracepoint_string = { [IPI_RESCHEDULE] = "Rescheduling interrupts", [IPI_CALL_FUNC] = "Function call interrupts", [IPI_CPU_STOP] = "CPU stop interrupts", [IPI_CPU_STOP_NMI] = "CPU stop NMIs", [IPI_TIMER] = "Timer broadcast interrupts", [IPI_IRQ_WORK] = "IRQ work interrupts", [IPI_CPU_BACKTRACE] = "CPU backtrace interrupts", [IPI_KGDB_ROUNDUP] = "KGDB roundup interrupts", }; static void smp_cross_call(const struct cpumask *target, unsigned int ipinr); unsigned long irq_err_count; int arch_show_interrupts(struct seq_file *p, int prec) { unsigned int cpu, i; for (i = 0; i < MAX_IPI; i++) { seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i, prec >= 4 ? " " : ""); for_each_online_cpu(cpu) seq_printf(p, "%10u ", irq_desc_kstat_cpu(ipi_desc[i], cpu)); seq_printf(p, " %s\n", ipi_types[i]); } seq_printf(p, "%*s: %10lu\n", prec, "Err", irq_err_count); return 0; } void arch_send_call_function_ipi_mask(const struct cpumask *mask) { smp_cross_call(mask, IPI_CALL_FUNC); } 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) { smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK); } #endif static void __noreturn local_cpu_stop(unsigned int cpu) { set_cpu_online(cpu, false); local_daif_mask(); sdei_mask_local_cpu(); cpu_park_loop(); } /* * We need to implement panic_smp_self_stop() for parallel panic() calls, so * that cpu_online_mask gets correctly updated and smp_send_stop() can skip * CPUs that have already stopped themselves. */ void __noreturn panic_smp_self_stop(void) { local_cpu_stop(smp_processor_id()); } static void __noreturn ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs) { #ifdef CONFIG_KEXEC_CORE /* * Use local_daif_mask() instead of local_irq_disable() to make sure * that pseudo-NMIs are disabled. The "crash stop" code starts with * an IRQ and falls back to NMI (which might be pseudo). If the IRQ * finally goes through right as we're timing out then the NMI could * interrupt us. It's better to prevent the NMI and let the IRQ * finish since the pt_regs will be better. */ local_daif_mask(); crash_save_cpu(regs, cpu); set_cpu_online(cpu, false); sdei_mask_local_cpu(); if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) __cpu_try_die(cpu); /* just in case */ cpu_park_loop(); #else BUG(); #endif } static void arm64_backtrace_ipi(cpumask_t *mask) { __ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask); } void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) { /* * NOTE: though nmi_trigger_cpumask_backtrace() has "nmi_" in the name, * nothing about it truly needs to be implemented using an NMI, it's * just that it's _allowed_ to work with NMIs. If ipi_should_be_nmi() * returned false our backtrace attempt will just use a regular IPI. */ nmi_trigger_cpumask_backtrace(mask, exclude_cpu, arm64_backtrace_ipi); } #ifdef CONFIG_KGDB void kgdb_roundup_cpus(void) { int this_cpu = raw_smp_processor_id(); int cpu; for_each_online_cpu(cpu) { /* No need to roundup ourselves */ if (cpu == this_cpu) continue; __ipi_send_single(ipi_desc[IPI_KGDB_ROUNDUP], cpu); } } #endif /* * Main handler for inter-processor interrupts */ static void do_handle_IPI(int ipinr) { unsigned int cpu = smp_processor_id(); if ((unsigned)ipinr < NR_IPI) trace_ipi_entry(ipi_types[ipinr]); switch (ipinr) { case IPI_RESCHEDULE: scheduler_ipi(); break; case IPI_CALL_FUNC: generic_smp_call_function_interrupt(); break; case IPI_CPU_STOP: case IPI_CPU_STOP_NMI: if (IS_ENABLED(CONFIG_KEXEC_CORE) && crash_stop) { ipi_cpu_crash_stop(cpu, get_irq_regs()); unreachable(); } else { local_cpu_stop(cpu); } break; #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST case IPI_TIMER: tick_receive_broadcast(); break; #endif #ifdef CONFIG_IRQ_WORK case IPI_IRQ_WORK: irq_work_run(); break; #endif case IPI_CPU_BACKTRACE: /* * NOTE: in some cases this _won't_ be NMI context. See the * comment in arch_trigger_cpumask_backtrace(). */ nmi_cpu_backtrace(get_irq_regs()); break; case IPI_KGDB_ROUNDUP: kgdb_nmicallback(cpu, get_irq_regs()); break; default: pr_crit("CPU%u: Unknown IPI message 0x%x\n", cpu, ipinr); break; } if ((unsigned)ipinr < NR_IPI) trace_ipi_exit(ipi_types[ipinr]); } static irqreturn_t ipi_handler(int irq, void *data) { do_handle_IPI(irq - ipi_irq_base); return IRQ_HANDLED; } static void smp_cross_call(const struct cpumask *target, unsigned int ipinr) { trace_ipi_raise(target, ipi_types[ipinr]); __ipi_send_mask(ipi_desc[ipinr], target); } static bool ipi_should_be_nmi(enum ipi_msg_type ipi) { if (!system_uses_irq_prio_masking()) return false; switch (ipi) { case IPI_CPU_STOP_NMI: case IPI_CPU_BACKTRACE: case IPI_KGDB_ROUNDUP: return true; default: return false; } } static void ipi_setup(int cpu) { int i; if (WARN_ON_ONCE(!ipi_irq_base)) return; for (i = 0; i < nr_ipi; i++) { if (ipi_should_be_nmi(i)) { prepare_percpu_nmi(ipi_irq_base + i); enable_percpu_nmi(ipi_irq_base + i, 0); } else { enable_percpu_irq(ipi_irq_base + i, 0); } } } #ifdef CONFIG_HOTPLUG_CPU static void ipi_teardown(int cpu) { int i; if (WARN_ON_ONCE(!ipi_irq_base)) return; for (i = 0; i < nr_ipi; i++) { if (ipi_should_be_nmi(i)) { disable_percpu_nmi(ipi_irq_base + i); teardown_percpu_nmi(ipi_irq_base + i); } else { disable_percpu_irq(ipi_irq_base + i); } } } #endif void __init set_smp_ipi_range(int ipi_base, int n) { int i; WARN_ON(n < MAX_IPI); nr_ipi = min(n, MAX_IPI); for (i = 0; i < nr_ipi; i++) { int err; if (ipi_should_be_nmi(i)) { err = request_percpu_nmi(ipi_base + i, ipi_handler, "IPI", &irq_stat); WARN(err, "Could not request IPI %d as NMI, err=%d\n", i, err); } else { err = request_percpu_irq(ipi_base + i, ipi_handler, "IPI", &irq_stat); WARN(err, "Could not request IPI %d as IRQ, err=%d\n", i, err); } ipi_desc[i] = irq_to_desc(ipi_base + i); irq_set_status_flags(ipi_base + i, IRQ_HIDDEN); } ipi_irq_base = ipi_base; /* Setup the boot CPU immediately */ ipi_setup(smp_processor_id()); } void arch_smp_send_reschedule(int cpu) { smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE); } #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL void arch_send_wakeup_ipi(unsigned int cpu) { /* * We use a scheduler IPI to wake the CPU as this avoids the need for a * dedicated IPI and we can safely handle spurious scheduler IPIs. */ smp_send_reschedule(cpu); } #endif #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST void tick_broadcast(const struct cpumask *mask) { smp_cross_call(mask, IPI_TIMER); } #endif /* * The number of CPUs online, not counting this CPU (which may not be * fully online and so not counted in num_online_cpus()). */ static inline unsigned int num_other_online_cpus(void) { unsigned int this_cpu_online = cpu_online(smp_processor_id()); return num_online_cpus() - this_cpu_online; } void smp_send_stop(void) { static unsigned long stop_in_progress; cpumask_t mask; unsigned long timeout; /* * If this cpu is the only one alive at this point in time, online or * not, there are no stop messages to be sent around, so just back out. */ if (num_other_online_cpus() == 0) goto skip_ipi; /* Only proceed if this is the first CPU to reach this code */ if (test_and_set_bit(0, &stop_in_progress)) return; /* * Send an IPI to all currently online CPUs except the CPU running * this code. * * NOTE: we don't do anything here to prevent other CPUs from coming * online after we snapshot `cpu_online_mask`. Ideally, the calling code * should do something to prevent other CPUs from coming up. This code * can be called in the panic path and thus it doesn't seem wise to * grab the CPU hotplug mutex ourselves. Worst case: * - If a CPU comes online as we're running, we'll likely notice it * during the 1 second wait below and then we'll catch it when we try * with an NMI (assuming NMIs are enabled) since we re-snapshot the * mask before sending an NMI. * - If we leave the function and see that CPUs are still online we'll * at least print a warning. Especially without NMIs this function * isn't foolproof anyway so calling code will just have to accept * the fact that there could be cases where a CPU can't be stopped. */ cpumask_copy(&mask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &mask); if (system_state <= SYSTEM_RUNNING) pr_crit("SMP: stopping secondary CPUs\n"); /* * Start with a normal IPI and wait up to one second for other CPUs to * stop. We do this first because it gives other processors a chance * to exit critical sections / drop locks and makes the rest of the * stop process (especially console flush) more robust. */ smp_cross_call(&mask, IPI_CPU_STOP); timeout = USEC_PER_SEC; while (num_other_online_cpus() && timeout--) udelay(1); /* * If CPUs are still online, try an NMI. There's no excuse for this to * be slow, so we only give them an extra 10 ms to respond. */ if (num_other_online_cpus() && ipi_should_be_nmi(IPI_CPU_STOP_NMI)) { smp_rmb(); cpumask_copy(&mask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &mask); pr_info("SMP: retry stop with NMI for CPUs %*pbl\n", cpumask_pr_args(&mask)); smp_cross_call(&mask, IPI_CPU_STOP_NMI); timeout = USEC_PER_MSEC * 10; while (num_other_online_cpus() && timeout--) udelay(1); } if (num_other_online_cpus()) { smp_rmb(); cpumask_copy(&mask, cpu_online_mask); cpumask_clear_cpu(smp_processor_id(), &mask); pr_warn("SMP: failed to stop secondary CPUs %*pbl\n", cpumask_pr_args(&mask)); } skip_ipi: sdei_mask_local_cpu(); } #ifdef CONFIG_KEXEC_CORE void crash_smp_send_stop(void) { /* * This function can be called twice in panic path, but obviously * we execute this only once. * * We use this same boolean to tell whether the IPI we send was a * stop or a "crash stop". */ if (crash_stop) return; crash_stop = 1; smp_send_stop(); sdei_handler_abort(); } bool smp_crash_stop_failed(void) { return num_other_online_cpus() != 0; } #endif static bool have_cpu_die(void) { #ifdef CONFIG_HOTPLUG_CPU int any_cpu = raw_smp_processor_id(); const struct cpu_operations *ops = get_cpu_ops(any_cpu); if (ops && ops->cpu_die) return true; #endif return false; } bool cpus_are_stuck_in_kernel(void) { bool smp_spin_tables = (num_possible_cpus() > 1 && !have_cpu_die()); return !!cpus_stuck_in_kernel || smp_spin_tables || is_protected_kvm_enabled(); }