// SPDX-License-Identifier: GPL-2.0-or-later /* * SMP support for ppc. * * Written by Cort Dougan (cort@cs.nmt.edu) borrowing a great * deal of code from the sparc and intel versions. * * Copyright (C) 1999 Cort Dougan * * PowerPC-64 Support added by Dave Engebretsen, Peter Bergner, and * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com */ #undef DEBUG #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 #ifdef CONFIG_PPC64 #include #endif #include #include #include #include #include #include #include #ifdef DEBUG #include #define DBG(fmt...) udbg_printf(fmt) #else #define DBG(fmt...) #endif #ifdef CONFIG_HOTPLUG_CPU /* State of each CPU during hotplug phases */ static DEFINE_PER_CPU(int, cpu_state) = { 0 }; #endif struct task_struct *secondary_current; bool has_big_cores; bool coregroup_enabled; bool thread_group_shares_l2; bool thread_group_shares_l3; DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map); DEFINE_PER_CPU(cpumask_var_t, cpu_smallcore_map); DEFINE_PER_CPU(cpumask_var_t, cpu_l2_cache_map); DEFINE_PER_CPU(cpumask_var_t, cpu_core_map); static DEFINE_PER_CPU(cpumask_var_t, cpu_coregroup_map); EXPORT_PER_CPU_SYMBOL(cpu_sibling_map); EXPORT_PER_CPU_SYMBOL(cpu_l2_cache_map); EXPORT_PER_CPU_SYMBOL(cpu_core_map); EXPORT_SYMBOL_GPL(has_big_cores); enum { #ifdef CONFIG_SCHED_SMT smt_idx, #endif cache_idx, mc_idx, die_idx, }; #define MAX_THREAD_LIST_SIZE 8 #define THREAD_GROUP_SHARE_L1 1 #define THREAD_GROUP_SHARE_L2_L3 2 struct thread_groups { unsigned int property; unsigned int nr_groups; unsigned int threads_per_group; unsigned int thread_list[MAX_THREAD_LIST_SIZE]; }; /* Maximum number of properties that groups of threads within a core can share */ #define MAX_THREAD_GROUP_PROPERTIES 2 struct thread_groups_list { unsigned int nr_properties; struct thread_groups property_tgs[MAX_THREAD_GROUP_PROPERTIES]; }; static struct thread_groups_list tgl[NR_CPUS] __initdata; /* * On big-cores system, thread_group_l1_cache_map for each CPU corresponds to * the set its siblings that share the L1-cache. */ DEFINE_PER_CPU(cpumask_var_t, thread_group_l1_cache_map); /* * On some big-cores system, thread_group_l2_cache_map for each CPU * corresponds to the set its siblings within the core that share the * L2-cache. */ DEFINE_PER_CPU(cpumask_var_t, thread_group_l2_cache_map); /* * On P10, thread_group_l3_cache_map for each CPU is equal to the * thread_group_l2_cache_map */ DEFINE_PER_CPU(cpumask_var_t, thread_group_l3_cache_map); /* SMP operations for this machine */ struct smp_ops_t *smp_ops; /* Can't be static due to PowerMac hackery */ volatile unsigned int cpu_callin_map[NR_CPUS]; int smt_enabled_at_boot = 1; /* * Returns 1 if the specified cpu should be brought up during boot. * Used to inhibit booting threads if they've been disabled or * limited on the command line */ int smp_generic_cpu_bootable(unsigned int nr) { /* Special case - we inhibit secondary thread startup * during boot if the user requests it. */ if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) { if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0) return 0; if (smt_enabled_at_boot && cpu_thread_in_core(nr) >= smt_enabled_at_boot) return 0; } return 1; } #ifdef CONFIG_PPC64 int smp_generic_kick_cpu(int nr) { if (nr < 0 || nr >= nr_cpu_ids) return -EINVAL; /* * The processor is currently spinning, waiting for the * cpu_start field to become non-zero After we set cpu_start, * the processor will continue on to secondary_start */ if (!paca_ptrs[nr]->cpu_start) { paca_ptrs[nr]->cpu_start = 1; smp_mb(); return 0; } #ifdef CONFIG_HOTPLUG_CPU /* * Ok it's not there, so it might be soft-unplugged, let's * try to bring it back */ generic_set_cpu_up(nr); smp_wmb(); smp_send_reschedule(nr); #endif /* CONFIG_HOTPLUG_CPU */ return 0; } #endif /* CONFIG_PPC64 */ static irqreturn_t call_function_action(int irq, void *data) { generic_smp_call_function_interrupt(); return IRQ_HANDLED; } static irqreturn_t reschedule_action(int irq, void *data) { scheduler_ipi(); return IRQ_HANDLED; } #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST static irqreturn_t tick_broadcast_ipi_action(int irq, void *data) { timer_broadcast_interrupt(); return IRQ_HANDLED; } #endif #ifdef CONFIG_NMI_IPI static irqreturn_t nmi_ipi_action(int irq, void *data) { smp_handle_nmi_ipi(get_irq_regs()); return IRQ_HANDLED; } #endif static irq_handler_t smp_ipi_action[] = { [PPC_MSG_CALL_FUNCTION] = call_function_action, [PPC_MSG_RESCHEDULE] = reschedule_action, #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST [PPC_MSG_TICK_BROADCAST] = tick_broadcast_ipi_action, #endif #ifdef CONFIG_NMI_IPI [PPC_MSG_NMI_IPI] = nmi_ipi_action, #endif }; /* * The NMI IPI is a fallback and not truly non-maskable. It is simpler * than going through the call function infrastructure, and strongly * serialized, so it is more appropriate for debugging. */ const char *smp_ipi_name[] = { [PPC_MSG_CALL_FUNCTION] = "ipi call function", [PPC_MSG_RESCHEDULE] = "ipi reschedule", #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST [PPC_MSG_TICK_BROADCAST] = "ipi tick-broadcast", #endif #ifdef CONFIG_NMI_IPI [PPC_MSG_NMI_IPI] = "nmi ipi", #endif }; /* optional function to request ipi, for controllers with >= 4 ipis */ int smp_request_message_ipi(int virq, int msg) { int err; if (msg < 0 || msg > PPC_MSG_NMI_IPI) return -EINVAL; #ifndef CONFIG_NMI_IPI if (msg == PPC_MSG_NMI_IPI) return 1; #endif err = request_irq(virq, smp_ipi_action[msg], IRQF_PERCPU | IRQF_NO_THREAD | IRQF_NO_SUSPEND, smp_ipi_name[msg], NULL); WARN(err < 0, "unable to request_irq %d for %s (rc %d)\n", virq, smp_ipi_name[msg], err); return err; } #ifdef CONFIG_PPC_SMP_MUXED_IPI struct cpu_messages { long messages; /* current messages */ }; static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_messages, ipi_message); void smp_muxed_ipi_set_message(int cpu, int msg) { struct cpu_messages *info = &per_cpu(ipi_message, cpu); char *message = (char *)&info->messages; /* * Order previous accesses before accesses in the IPI handler. */ smp_mb(); WRITE_ONCE(message[msg], 1); } void smp_muxed_ipi_message_pass(int cpu, int msg) { smp_muxed_ipi_set_message(cpu, msg); /* * cause_ipi functions are required to include a full barrier * before doing whatever causes the IPI. */ smp_ops->cause_ipi(cpu); } #ifdef __BIG_ENDIAN__ #define IPI_MESSAGE(A) (1uL << ((BITS_PER_LONG - 8) - 8 * (A))) #else #define IPI_MESSAGE(A) (1uL << (8 * (A))) #endif irqreturn_t smp_ipi_demux(void) { mb(); /* order any irq clear */ return smp_ipi_demux_relaxed(); } /* sync-free variant. Callers should ensure synchronization */ irqreturn_t smp_ipi_demux_relaxed(void) { struct cpu_messages *info; unsigned long all; info = this_cpu_ptr(&ipi_message); do { all = xchg(&info->messages, 0); #if defined(CONFIG_KVM_XICS) && defined(CONFIG_KVM_BOOK3S_HV_POSSIBLE) /* * Must check for PPC_MSG_RM_HOST_ACTION messages * before PPC_MSG_CALL_FUNCTION messages because when * a VM is destroyed, we call kick_all_cpus_sync() * to ensure that any pending PPC_MSG_RM_HOST_ACTION * messages have completed before we free any VCPUs. */ if (all & IPI_MESSAGE(PPC_MSG_RM_HOST_ACTION)) kvmppc_xics_ipi_action(); #endif if (all & IPI_MESSAGE(PPC_MSG_CALL_FUNCTION)) generic_smp_call_function_interrupt(); if (all & IPI_MESSAGE(PPC_MSG_RESCHEDULE)) scheduler_ipi(); #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST if (all & IPI_MESSAGE(PPC_MSG_TICK_BROADCAST)) timer_broadcast_interrupt(); #endif #ifdef CONFIG_NMI_IPI if (all & IPI_MESSAGE(PPC_MSG_NMI_IPI)) nmi_ipi_action(0, NULL); #endif } while (READ_ONCE(info->messages)); return IRQ_HANDLED; } #endif /* CONFIG_PPC_SMP_MUXED_IPI */ static inline void do_message_pass(int cpu, int msg) { if (smp_ops->message_pass) smp_ops->message_pass(cpu, msg); #ifdef CONFIG_PPC_SMP_MUXED_IPI else smp_muxed_ipi_message_pass(cpu, msg); #endif } void arch_smp_send_reschedule(int cpu) { if (likely(smp_ops)) do_message_pass(cpu, PPC_MSG_RESCHEDULE); } EXPORT_SYMBOL_GPL(arch_smp_send_reschedule); void arch_send_call_function_single_ipi(int cpu) { do_message_pass(cpu, PPC_MSG_CALL_FUNCTION); } void arch_send_call_function_ipi_mask(const struct cpumask *mask) { unsigned int cpu; for_each_cpu(cpu, mask) do_message_pass(cpu, PPC_MSG_CALL_FUNCTION); } #ifdef CONFIG_NMI_IPI /* * "NMI IPI" system. * * NMI IPIs may not be recoverable, so should not be used as ongoing part of * a running system. They can be used for crash, debug, halt/reboot, etc. * * The IPI call waits with interrupts disabled until all targets enter the * NMI handler, then returns. Subsequent IPIs can be issued before targets * have returned from their handlers, so there is no guarantee about * concurrency or re-entrancy. * * A new NMI can be issued before all targets exit the handler. * * The IPI call may time out without all targets entering the NMI handler. * In that case, there is some logic to recover (and ignore subsequent * NMI interrupts that may eventually be raised), but the platform interrupt * handler may not be able to distinguish this from other exception causes, * which may cause a crash. */ static atomic_t __nmi_ipi_lock = ATOMIC_INIT(0); static struct cpumask nmi_ipi_pending_mask; static bool nmi_ipi_busy = false; static void (*nmi_ipi_function)(struct pt_regs *) = NULL; noinstr static void nmi_ipi_lock_start(unsigned long *flags) { raw_local_irq_save(*flags); hard_irq_disable(); while (raw_atomic_cmpxchg(&__nmi_ipi_lock, 0, 1) == 1) { raw_local_irq_restore(*flags); spin_until_cond(raw_atomic_read(&__nmi_ipi_lock) == 0); raw_local_irq_save(*flags); hard_irq_disable(); } } noinstr static void nmi_ipi_lock(void) { while (raw_atomic_cmpxchg(&__nmi_ipi_lock, 0, 1) == 1) spin_until_cond(raw_atomic_read(&__nmi_ipi_lock) == 0); } noinstr static void nmi_ipi_unlock(void) { smp_mb(); WARN_ON(raw_atomic_read(&__nmi_ipi_lock) != 1); raw_atomic_set(&__nmi_ipi_lock, 0); } noinstr static void nmi_ipi_unlock_end(unsigned long *flags) { nmi_ipi_unlock(); raw_local_irq_restore(*flags); } /* * Platform NMI handler calls this to ack */ noinstr int smp_handle_nmi_ipi(struct pt_regs *regs) { void (*fn)(struct pt_regs *) = NULL; unsigned long flags; int me = raw_smp_processor_id(); int ret = 0; /* * Unexpected NMIs are possible here because the interrupt may not * be able to distinguish NMI IPIs from other types of NMIs, or * because the caller may have timed out. */ nmi_ipi_lock_start(&flags); if (cpumask_test_cpu(me, &nmi_ipi_pending_mask)) { cpumask_clear_cpu(me, &nmi_ipi_pending_mask); fn = READ_ONCE(nmi_ipi_function); WARN_ON_ONCE(!fn); ret = 1; } nmi_ipi_unlock_end(&flags); if (fn) fn(regs); return ret; } static void do_smp_send_nmi_ipi(int cpu, bool safe) { if (!safe && smp_ops->cause_nmi_ipi && smp_ops->cause_nmi_ipi(cpu)) return; if (cpu >= 0) { do_message_pass(cpu, PPC_MSG_NMI_IPI); } else { int c; for_each_online_cpu(c) { if (c == raw_smp_processor_id()) continue; do_message_pass(c, PPC_MSG_NMI_IPI); } } } /* * - cpu is the target CPU (must not be this CPU), or NMI_IPI_ALL_OTHERS. * - fn is the target callback function. * - delay_us > 0 is the delay before giving up waiting for targets to * begin executing the handler, == 0 specifies indefinite delay. */ static int __smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us, bool safe) { unsigned long flags; int me = raw_smp_processor_id(); int ret = 1; BUG_ON(cpu == me); BUG_ON(cpu < 0 && cpu != NMI_IPI_ALL_OTHERS); if (unlikely(!smp_ops)) return 0; nmi_ipi_lock_start(&flags); while (nmi_ipi_busy) { nmi_ipi_unlock_end(&flags); spin_until_cond(!nmi_ipi_busy); nmi_ipi_lock_start(&flags); } nmi_ipi_busy = true; nmi_ipi_function = fn; WARN_ON_ONCE(!cpumask_empty(&nmi_ipi_pending_mask)); if (cpu < 0) { /* ALL_OTHERS */ cpumask_copy(&nmi_ipi_pending_mask, cpu_online_mask); cpumask_clear_cpu(me, &nmi_ipi_pending_mask); } else { cpumask_set_cpu(cpu, &nmi_ipi_pending_mask); } nmi_ipi_unlock(); /* Interrupts remain hard disabled */ do_smp_send_nmi_ipi(cpu, safe); nmi_ipi_lock(); /* nmi_ipi_busy is set here, so unlock/lock is okay */ while (!cpumask_empty(&nmi_ipi_pending_mask)) { nmi_ipi_unlock(); udelay(1); nmi_ipi_lock(); if (delay_us) { delay_us--; if (!delay_us) break; } } if (!cpumask_empty(&nmi_ipi_pending_mask)) { /* Timeout waiting for CPUs to call smp_handle_nmi_ipi */ ret = 0; cpumask_clear(&nmi_ipi_pending_mask); } nmi_ipi_function = NULL; nmi_ipi_busy = false; nmi_ipi_unlock_end(&flags); return ret; } int smp_send_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us) { return __smp_send_nmi_ipi(cpu, fn, delay_us, false); } int smp_send_safe_nmi_ipi(int cpu, void (*fn)(struct pt_regs *), u64 delay_us) { return __smp_send_nmi_ipi(cpu, fn, delay_us, true); } #endif /* CONFIG_NMI_IPI */ #ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST void tick_broadcast(const struct cpumask *mask) { unsigned int cpu; for_each_cpu(cpu, mask) do_message_pass(cpu, PPC_MSG_TICK_BROADCAST); } #endif #ifdef CONFIG_DEBUGGER static void debugger_ipi_callback(struct pt_regs *regs) { debugger_ipi(regs); } void smp_send_debugger_break(void) { smp_send_nmi_ipi(NMI_IPI_ALL_OTHERS, debugger_ipi_callback, 1000000); } #endif #ifdef CONFIG_KEXEC_CORE void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *)) { int cpu; smp_send_nmi_ipi(NMI_IPI_ALL_OTHERS, crash_ipi_callback, 1000000); if (kdump_in_progress() && crash_wake_offline) { for_each_present_cpu(cpu) { if (cpu_online(cpu)) continue; /* * crash_ipi_callback will wait for * all cpus, including offline CPUs. * We don't care about nmi_ipi_function. * Offline cpus will jump straight into * crash_ipi_callback, we can skip the * entire NMI dance and waiting for * cpus to clear pending mask, etc. */ do_smp_send_nmi_ipi(cpu, false); } } } #endif void crash_smp_send_stop(void) { static bool stopped = false; /* * In case of fadump, register data for all CPUs is captured by f/w * on ibm,os-term rtas call. Skip IPI callbacks to other CPUs before * this rtas call to avoid tricky post processing of those CPUs' * backtraces. */ if (should_fadump_crash()) return; if (stopped) return; stopped = true; #ifdef CONFIG_KEXEC_CORE if (kexec_crash_image) { crash_kexec_prepare(); return; } #endif smp_send_stop(); } #ifdef CONFIG_NMI_IPI static void nmi_stop_this_cpu(struct pt_regs *regs) { /* * IRQs are already hard disabled by the smp_handle_nmi_ipi. */ set_cpu_online(smp_processor_id(), false); spin_begin(); while (1) spin_cpu_relax(); } void smp_send_stop(void) { smp_send_nmi_ipi(NMI_IPI_ALL_OTHERS, nmi_stop_this_cpu, 1000000); } #else /* CONFIG_NMI_IPI */ static void stop_this_cpu(void *dummy) { hard_irq_disable(); /* * Offlining CPUs in stop_this_cpu can result in scheduler warnings, * (see commit de6e5d38417e), but printk_safe_flush_on_panic() wants * to know other CPUs are offline before it breaks locks to flush * printk buffers, in case we panic()ed while holding the lock. */ set_cpu_online(smp_processor_id(), false); spin_begin(); while (1) spin_cpu_relax(); } void smp_send_stop(void) { static bool stopped = false; /* * Prevent waiting on csd lock from a previous smp_send_stop. * This is racy, but in general callers try to do the right * thing and only fire off one smp_send_stop (e.g., see * kernel/panic.c) */ if (stopped) return; stopped = true; smp_call_function(stop_this_cpu, NULL, 0); } #endif /* CONFIG_NMI_IPI */ static struct task_struct *current_set[NR_CPUS]; static void smp_store_cpu_info(int id) { per_cpu(cpu_pvr, id) = mfspr(SPRN_PVR); #ifdef CONFIG_PPC_E500 per_cpu(next_tlbcam_idx, id) = (mfspr(SPRN_TLB1CFG) & TLBnCFG_N_ENTRY) - 1; #endif } /* * Relationships between CPUs are maintained in a set of per-cpu cpumasks so * rather than just passing around the cpumask we pass around a function that * returns the that cpumask for the given CPU. */ static void set_cpus_related(int i, int j, struct cpumask *(*get_cpumask)(int)) { cpumask_set_cpu(i, get_cpumask(j)); cpumask_set_cpu(j, get_cpumask(i)); } #ifdef CONFIG_HOTPLUG_CPU static void set_cpus_unrelated(int i, int j, struct cpumask *(*get_cpumask)(int)) { cpumask_clear_cpu(i, get_cpumask(j)); cpumask_clear_cpu(j, get_cpumask(i)); } #endif /* * Extends set_cpus_related. Instead of setting one CPU at a time in * dstmask, set srcmask at oneshot. dstmask should be super set of srcmask. */ static void or_cpumasks_related(int i, int j, struct cpumask *(*srcmask)(int), struct cpumask *(*dstmask)(int)) { struct cpumask *mask; int k; mask = srcmask(j); for_each_cpu(k, srcmask(i)) cpumask_or(dstmask(k), dstmask(k), mask); if (i == j) return; mask = srcmask(i); for_each_cpu(k, srcmask(j)) cpumask_or(dstmask(k), dstmask(k), mask); } /* * parse_thread_groups: Parses the "ibm,thread-groups" device tree * property for the CPU device node @dn and stores * the parsed output in the thread_groups_list * structure @tglp. * * @dn: The device node of the CPU device. * @tglp: Pointer to a thread group list structure into which the parsed * output of "ibm,thread-groups" is stored. * * ibm,thread-groups[0..N-1] array defines which group of threads in * the CPU-device node can be grouped together based on the property. * * This array can represent thread groupings for multiple properties. * * ibm,thread-groups[i + 0] tells us the property based on which the * threads are being grouped together. If this value is 1, it implies * that the threads in the same group share L1, translation cache. If * the value is 2, it implies that the threads in the same group share * the same L2 cache. * * ibm,thread-groups[i+1] tells us how many such thread groups exist for the * property ibm,thread-groups[i] * * ibm,thread-groups[i+2] tells us the number of threads in each such * group. * Suppose k = (ibm,thread-groups[i+1] * ibm,thread-groups[i+2]), then, * * ibm,thread-groups[i+3..i+k+2] (is the list of threads identified by * "ibm,ppc-interrupt-server#s" arranged as per their membership in * the grouping. * * Example: * If "ibm,thread-groups" = [1,2,4,8,10,12,14,9,11,13,15,2,2,4,8,10,12,14,9,11,13,15] * This can be decomposed up into two consecutive arrays: * a) [1,2,4,8,10,12,14,9,11,13,15] * b) [2,2,4,8,10,12,14,9,11,13,15] * * where in, * * a) provides information of Property "1" being shared by "2" groups, * each with "4" threads each. The "ibm,ppc-interrupt-server#s" of * the first group is {8,10,12,14} and the * "ibm,ppc-interrupt-server#s" of the second group is * {9,11,13,15}. Property "1" is indicative of the thread in the * group sharing L1 cache, translation cache and Instruction Data * flow. * * b) provides information of Property "2" being shared by "2" groups, * each group with "4" threads. The "ibm,ppc-interrupt-server#s" of * the first group is {8,10,12,14} and the * "ibm,ppc-interrupt-server#s" of the second group is * {9,11,13,15}. Property "2" indicates that the threads in each * group share the L2-cache. * * Returns 0 on success, -EINVAL if the property does not exist, * -ENODATA if property does not have a value, and -EOVERFLOW if the * property data isn't large enough. */ static int parse_thread_groups(struct device_node *dn, struct thread_groups_list *tglp) { unsigned int property_idx = 0; u32 *thread_group_array; size_t total_threads; int ret = 0, count; u32 *thread_list; int i = 0; count = of_property_count_u32_elems(dn, "ibm,thread-groups"); thread_group_array = kcalloc(count, sizeof(u32), GFP_KERNEL); ret = of_property_read_u32_array(dn, "ibm,thread-groups", thread_group_array, count); if (ret) goto out_free; while (i < count && property_idx < MAX_THREAD_GROUP_PROPERTIES) { int j; struct thread_groups *tg = &tglp->property_tgs[property_idx++]; tg->property = thread_group_array[i]; tg->nr_groups = thread_group_array[i + 1]; tg->threads_per_group = thread_group_array[i + 2]; total_threads = tg->nr_groups * tg->threads_per_group; thread_list = &thread_group_array[i + 3]; for (j = 0; j < total_threads; j++) tg->thread_list[j] = thread_list[j]; i = i + 3 + total_threads; } tglp->nr_properties = property_idx; out_free: kfree(thread_group_array); return ret; } /* * get_cpu_thread_group_start : Searches the thread group in tg->thread_list * that @cpu belongs to. * * @cpu : The logical CPU whose thread group is being searched. * @tg : The thread-group structure of the CPU node which @cpu belongs * to. * * Returns the index to tg->thread_list that points to the start * of the thread_group that @cpu belongs to. * * Returns -1 if cpu doesn't belong to any of the groups pointed to by * tg->thread_list. */ static int get_cpu_thread_group_start(int cpu, struct thread_groups *tg) { int hw_cpu_id = get_hard_smp_processor_id(cpu); int i, j; for (i = 0; i < tg->nr_groups; i++) { int group_start = i * tg->threads_per_group; for (j = 0; j < tg->threads_per_group; j++) { int idx = group_start + j; if (tg->thread_list[idx] == hw_cpu_id) return group_start; } } return -1; } static struct thread_groups *__init get_thread_groups(int cpu, int group_property, int *err) { struct device_node *dn = of_get_cpu_node(cpu, NULL); struct thread_groups_list *cpu_tgl = &tgl[cpu]; struct thread_groups *tg = NULL; int i; *err = 0; if (!dn) { *err = -ENODATA; return NULL; } if (!cpu_tgl->nr_properties) { *err = parse_thread_groups(dn, cpu_tgl); if (*err) goto out; } for (i = 0; i < cpu_tgl->nr_properties; i++) { if (cpu_tgl->property_tgs[i].property == group_property) { tg = &cpu_tgl->property_tgs[i]; break; } } if (!tg) *err = -EINVAL; out: of_node_put(dn); return tg; } static int __init update_mask_from_threadgroup(cpumask_var_t *mask, struct thread_groups *tg, int cpu, int cpu_group_start) { int first_thread = cpu_first_thread_sibling(cpu); int i; zalloc_cpumask_var_node(mask, GFP_KERNEL, cpu_to_node(cpu)); for (i = first_thread; i < first_thread + threads_per_core; i++) { int i_group_start = get_cpu_thread_group_start(i, tg); if (unlikely(i_group_start == -1)) { WARN_ON_ONCE(1); return -ENODATA; } if (i_group_start == cpu_group_start) cpumask_set_cpu(i, *mask); } return 0; } static int __init init_thread_group_cache_map(int cpu, int cache_property) { int cpu_group_start = -1, err = 0; struct thread_groups *tg = NULL; cpumask_var_t *mask = NULL; if (cache_property != THREAD_GROUP_SHARE_L1 && cache_property != THREAD_GROUP_SHARE_L2_L3) return -EINVAL; tg = get_thread_groups(cpu, cache_property, &err); if (!tg) return err; cpu_group_start = get_cpu_thread_group_start(cpu, tg); if (unlikely(cpu_group_start == -1)) { WARN_ON_ONCE(1); return -ENODATA; } if (cache_property == THREAD_GROUP_SHARE_L1) { mask = &per_cpu(thread_group_l1_cache_map, cpu); update_mask_from_threadgroup(mask, tg, cpu, cpu_group_start); } else if (cache_property == THREAD_GROUP_SHARE_L2_L3) { mask = &per_cpu(thread_group_l2_cache_map, cpu); update_mask_from_threadgroup(mask, tg, cpu, cpu_group_start); mask = &per_cpu(thread_group_l3_cache_map, cpu); update_mask_from_threadgroup(mask, tg, cpu, cpu_group_start); } return 0; } static bool shared_caches; #ifdef CONFIG_SCHED_SMT /* cpumask of CPUs with asymmetric SMT dependency */ static int powerpc_smt_flags(void) { int flags = SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES; if (cpu_has_feature(CPU_FTR_ASYM_SMT)) { printk_once(KERN_INFO "Enabling Asymmetric SMT scheduling\n"); flags |= SD_ASYM_PACKING; } return flags; } #endif /* * P9 has a slightly odd architecture where pairs of cores share an L2 cache. * This topology makes it *much* cheaper to migrate tasks between adjacent cores * since the migrated task remains cache hot. We want to take advantage of this * at the scheduler level so an extra topology level is required. */ static int powerpc_shared_cache_flags(void) { return SD_SHARE_PKG_RESOURCES; } /* * We can't just pass cpu_l2_cache_mask() directly because * returns a non-const pointer and the compiler barfs on that. */ static const struct cpumask *shared_cache_mask(int cpu) { return per_cpu(cpu_l2_cache_map, cpu); } #ifdef CONFIG_SCHED_SMT static const struct cpumask *smallcore_smt_mask(int cpu) { return cpu_smallcore_mask(cpu); } #endif static struct cpumask *cpu_coregroup_mask(int cpu) { return per_cpu(cpu_coregroup_map, cpu); } static bool has_coregroup_support(void) { return coregroup_enabled; } static const struct cpumask *cpu_mc_mask(int cpu) { return cpu_coregroup_mask(cpu); } static struct sched_domain_topology_level powerpc_topology[] = { #ifdef CONFIG_SCHED_SMT { cpu_smt_mask, powerpc_smt_flags, SD_INIT_NAME(SMT) }, #endif { shared_cache_mask, powerpc_shared_cache_flags, SD_INIT_NAME(CACHE) }, { cpu_mc_mask, SD_INIT_NAME(MC) }, { cpu_cpu_mask, SD_INIT_NAME(DIE) }, { NULL, }, }; static int __init init_big_cores(void) { int cpu; for_each_possible_cpu(cpu) { int err = init_thread_group_cache_map(cpu, THREAD_GROUP_SHARE_L1); if (err) return err; zalloc_cpumask_var_node(&per_cpu(cpu_smallcore_map, cpu), GFP_KERNEL, cpu_to_node(cpu)); } has_big_cores = true; for_each_possible_cpu(cpu) { int err = init_thread_group_cache_map(cpu, THREAD_GROUP_SHARE_L2_L3); if (err) return err; } thread_group_shares_l2 = true; thread_group_shares_l3 = true; pr_debug("L2/L3 cache only shared by the threads in the small core\n"); return 0; } void __init smp_prepare_cpus(unsigned int max_cpus) { unsigned int cpu; DBG("smp_prepare_cpus\n"); /* * setup_cpu may need to be called on the boot cpu. We haven't * spun any cpus up but lets be paranoid. */ BUG_ON(boot_cpuid != smp_processor_id()); /* Fixup boot cpu */ smp_store_cpu_info(boot_cpuid); cpu_callin_map[boot_cpuid] = 1; for_each_possible_cpu(cpu) { zalloc_cpumask_var_node(&per_cpu(cpu_sibling_map, cpu), GFP_KERNEL, cpu_to_node(cpu)); zalloc_cpumask_var_node(&per_cpu(cpu_l2_cache_map, cpu), GFP_KERNEL, cpu_to_node(cpu)); zalloc_cpumask_var_node(&per_cpu(cpu_core_map, cpu), GFP_KERNEL, cpu_to_node(cpu)); if (has_coregroup_support()) zalloc_cpumask_var_node(&per_cpu(cpu_coregroup_map, cpu), GFP_KERNEL, cpu_to_node(cpu)); #ifdef CONFIG_NUMA /* * numa_node_id() works after this. */ if (cpu_present(cpu)) { set_cpu_numa_node(cpu, numa_cpu_lookup_table[cpu]); set_cpu_numa_mem(cpu, local_memory_node(numa_cpu_lookup_table[cpu])); } #endif } /* Init the cpumasks so the boot CPU is related to itself */ cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid)); cpumask_set_cpu(boot_cpuid, cpu_l2_cache_mask(boot_cpuid)); cpumask_set_cpu(boot_cpuid, cpu_core_mask(boot_cpuid)); if (has_coregroup_support()) cpumask_set_cpu(boot_cpuid, cpu_coregroup_mask(boot_cpuid)); init_big_cores(); if (has_big_cores) { cpumask_set_cpu(boot_cpuid, cpu_smallcore_mask(boot_cpuid)); } if (cpu_to_chip_id(boot_cpuid) != -1) { int idx = DIV_ROUND_UP(num_possible_cpus(), threads_per_core); /* * All threads of a core will all belong to the same core, * chip_id_lookup_table will have one entry per core. * Assumption: if boot_cpuid doesn't have a chip-id, then no * other CPUs, will also not have chip-id. */ chip_id_lookup_table = kcalloc(idx, sizeof(int), GFP_KERNEL); if (chip_id_lookup_table) memset(chip_id_lookup_table, -1, sizeof(int) * idx); } if (smp_ops && smp_ops->probe) smp_ops->probe(); } void smp_prepare_boot_cpu(void) { BUG_ON(smp_processor_id() != boot_cpuid); #ifdef CONFIG_PPC64 paca_ptrs[boot_cpuid]->__current = current; #endif set_numa_node(numa_cpu_lookup_table[boot_cpuid]); current_set[boot_cpuid] = current; } #ifdef CONFIG_HOTPLUG_CPU int generic_cpu_disable(void) { unsigned int cpu = smp_processor_id(); if (cpu == boot_cpuid) return -EBUSY; set_cpu_online(cpu, false); #ifdef CONFIG_PPC64 vdso_data->processorCount--; #endif /* Update affinity of all IRQs previously aimed at this CPU */ irq_migrate_all_off_this_cpu(); /* * Depending on the details of the interrupt controller, it's possible * that one of the interrupts we just migrated away from this CPU is * actually already pending on this CPU. If we leave it in that state * the interrupt will never be EOI'ed, and will never fire again. So * temporarily enable interrupts here, to allow any pending interrupt to * be received (and EOI'ed), before we take this CPU offline. */ local_irq_enable(); mdelay(1); local_irq_disable(); return 0; } void generic_cpu_die(unsigned int cpu) { int i; for (i = 0; i < 100; i++) { smp_rmb(); if (is_cpu_dead(cpu)) return; msleep(100); } printk(KERN_ERR "CPU%d didn't die...\n", cpu); } void generic_set_cpu_dead(unsigned int cpu) { per_cpu(cpu_state, cpu) = CPU_DEAD; } /* * The cpu_state should be set to CPU_UP_PREPARE in kick_cpu(), otherwise * the cpu_state is always CPU_DEAD after calling generic_set_cpu_dead(), * which makes the delay in generic_cpu_die() not happen. */ void generic_set_cpu_up(unsigned int cpu) { per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; } int generic_check_cpu_restart(unsigned int cpu) { return per_cpu(cpu_state, cpu) == CPU_UP_PREPARE; } int is_cpu_dead(unsigned int cpu) { return per_cpu(cpu_state, cpu) == CPU_DEAD; } static bool secondaries_inhibited(void) { return kvm_hv_mode_active(); } #else /* HOTPLUG_CPU */ #define secondaries_inhibited() 0 #endif static void cpu_idle_thread_init(unsigned int cpu, struct task_struct *idle) { #ifdef CONFIG_PPC64 paca_ptrs[cpu]->__current = idle; paca_ptrs[cpu]->kstack = (unsigned long)task_stack_page(idle) + THREAD_SIZE - STACK_FRAME_MIN_SIZE; #endif task_thread_info(idle)->cpu = cpu; secondary_current = current_set[cpu] = idle; } int __cpu_up(unsigned int cpu, struct task_struct *tidle) { const unsigned long boot_spin_ms = 5 * MSEC_PER_SEC; const bool booting = system_state < SYSTEM_RUNNING; const unsigned long hp_spin_ms = 1; unsigned long deadline; int rc; const unsigned long spin_wait_ms = booting ? boot_spin_ms : hp_spin_ms; /* * Don't allow secondary threads to come online if inhibited */ if (threads_per_core > 1 && secondaries_inhibited() && cpu_thread_in_subcore(cpu)) return -EBUSY; if (smp_ops == NULL || (smp_ops->cpu_bootable && !smp_ops->cpu_bootable(cpu))) return -EINVAL; cpu_idle_thread_init(cpu, tidle); /* * The platform might need to allocate resources prior to bringing * up the CPU */ if (smp_ops->prepare_cpu) { rc = smp_ops->prepare_cpu(cpu); if (rc) return rc; } /* Make sure callin-map entry is 0 (can be leftover a CPU * hotplug */ cpu_callin_map[cpu] = 0; /* The information for processor bringup must * be written out to main store before we release * the processor. */ smp_mb(); /* wake up cpus */ DBG("smp: kicking cpu %d\n", cpu); rc = smp_ops->kick_cpu(cpu); if (rc) { pr_err("smp: failed starting cpu %d (rc %d)\n", cpu, rc); return rc; } /* * At boot time, simply spin on the callin word until the * deadline passes. * * At run time, spin for an optimistic amount of time to avoid * sleeping in the common case. */ deadline = jiffies + msecs_to_jiffies(spin_wait_ms); spin_until_cond(cpu_callin_map[cpu] || time_is_before_jiffies(deadline)); if (!cpu_callin_map[cpu] && system_state >= SYSTEM_RUNNING) { const unsigned long sleep_interval_us = 10 * USEC_PER_MSEC; const unsigned long sleep_wait_ms = 100 * MSEC_PER_SEC; deadline = jiffies + msecs_to_jiffies(sleep_wait_ms); while (!cpu_callin_map[cpu] && time_is_after_jiffies(deadline)) fsleep(sleep_interval_us); } if (!cpu_callin_map[cpu]) { printk(KERN_ERR "Processor %u is stuck.\n", cpu); return -ENOENT; } DBG("Processor %u found.\n", cpu); if (smp_ops->give_timebase) smp_ops->give_timebase(); /* Wait until cpu puts itself in the online & active maps */ spin_until_cond(cpu_online(cpu)); return 0; } /* Return the value of the reg property corresponding to the given * logical cpu. */ int cpu_to_core_id(int cpu) { struct device_node *np; int id = -1; np = of_get_cpu_node(cpu, NULL); if (!np) goto out; id = of_get_cpu_hwid(np, 0); out: of_node_put(np); return id; } EXPORT_SYMBOL_GPL(cpu_to_core_id); /* Helper routines for cpu to core mapping */ int cpu_core_index_of_thread(int cpu) { return cpu >> threads_shift; } EXPORT_SYMBOL_GPL(cpu_core_index_of_thread); int cpu_first_thread_of_core(int core) { return core << threads_shift; } EXPORT_SYMBOL_GPL(cpu_first_thread_of_core); /* Must be called when no change can occur to cpu_present_mask, * i.e. during cpu online or offline. */ static struct device_node *cpu_to_l2cache(int cpu) { struct device_node *np; struct device_node *cache; if (!cpu_present(cpu)) return NULL; np = of_get_cpu_node(cpu, NULL); if (np == NULL) return NULL; cache = of_find_next_cache_node(np); of_node_put(np); return cache; } static bool update_mask_by_l2(int cpu, cpumask_var_t *mask) { struct cpumask *(*submask_fn)(int) = cpu_sibling_mask; struct device_node *l2_cache, *np; int i; if (has_big_cores) submask_fn = cpu_smallcore_mask; /* * If the threads in a thread-group share L2 cache, then the * L2-mask can be obtained from thread_group_l2_cache_map. */ if (thread_group_shares_l2) { cpumask_set_cpu(cpu, cpu_l2_cache_mask(cpu)); for_each_cpu(i, per_cpu(thread_group_l2_cache_map, cpu)) { if (cpu_online(i)) set_cpus_related(i, cpu, cpu_l2_cache_mask); } /* Verify that L1-cache siblings are a subset of L2 cache-siblings */ if (!cpumask_equal(submask_fn(cpu), cpu_l2_cache_mask(cpu)) && !cpumask_subset(submask_fn(cpu), cpu_l2_cache_mask(cpu))) { pr_warn_once("CPU %d : Inconsistent L1 and L2 cache siblings\n", cpu); } return true; } l2_cache = cpu_to_l2cache(cpu); if (!l2_cache || !*mask) { /* Assume only core siblings share cache with this CPU */ for_each_cpu(i, cpu_sibling_mask(cpu)) set_cpus_related(cpu, i, cpu_l2_cache_mask); return false; } cpumask_and(*mask, cpu_online_mask, cpu_cpu_mask(cpu)); /* Update l2-cache mask with all the CPUs that are part of submask */ or_cpumasks_related(cpu, cpu, submask_fn, cpu_l2_cache_mask); /* Skip all CPUs already part of current CPU l2-cache mask */ cpumask_andnot(*mask, *mask, cpu_l2_cache_mask(cpu)); for_each_cpu(i, *mask) { /* * when updating the marks the current CPU has not been marked * online, but we need to update the cache masks */ np = cpu_to_l2cache(i); /* Skip all CPUs already part of current CPU l2-cache */ if (np == l2_cache) { or_cpumasks_related(cpu, i, submask_fn, cpu_l2_cache_mask); cpumask_andnot(*mask, *mask, submask_fn(i)); } else { cpumask_andnot(*mask, *mask, cpu_l2_cache_mask(i)); } of_node_put(np); } of_node_put(l2_cache); return true; } #ifdef CONFIG_HOTPLUG_CPU static void remove_cpu_from_masks(int cpu) { struct cpumask *(*mask_fn)(int) = cpu_sibling_mask; int i; unmap_cpu_from_node(cpu); if (shared_caches) mask_fn = cpu_l2_cache_mask; for_each_cpu(i, mask_fn(cpu)) { set_cpus_unrelated(cpu, i, cpu_l2_cache_mask); set_cpus_unrelated(cpu, i, cpu_sibling_mask); if (has_big_cores) set_cpus_unrelated(cpu, i, cpu_smallcore_mask); } for_each_cpu(i, cpu_core_mask(cpu)) set_cpus_unrelated(cpu, i, cpu_core_mask); if (has_coregroup_support()) { for_each_cpu(i, cpu_coregroup_mask(cpu)) set_cpus_unrelated(cpu, i, cpu_coregroup_mask); } } #endif static inline void add_cpu_to_smallcore_masks(int cpu) { int i; if (!has_big_cores) return; cpumask_set_cpu(cpu, cpu_smallcore_mask(cpu)); for_each_cpu(i, per_cpu(thread_group_l1_cache_map, cpu)) { if (cpu_online(i)) set_cpus_related(i, cpu, cpu_smallcore_mask); } } static void update_coregroup_mask(int cpu, cpumask_var_t *mask) { struct cpumask *(*submask_fn)(int) = cpu_sibling_mask; int coregroup_id = cpu_to_coregroup_id(cpu); int i; if (shared_caches) submask_fn = cpu_l2_cache_mask; if (!*mask) { /* Assume only siblings are part of this CPU's coregroup */ for_each_cpu(i, submask_fn(cpu)) set_cpus_related(cpu, i, cpu_coregroup_mask); return; } cpumask_and(*mask, cpu_online_mask, cpu_cpu_mask(cpu)); /* Update coregroup mask with all the CPUs that are part of submask */ or_cpumasks_related(cpu, cpu, submask_fn, cpu_coregroup_mask); /* Skip all CPUs already part of coregroup mask */ cpumask_andnot(*mask, *mask, cpu_coregroup_mask(cpu)); for_each_cpu(i, *mask) { /* Skip all CPUs not part of this coregroup */ if (coregroup_id == cpu_to_coregroup_id(i)) { or_cpumasks_related(cpu, i, submask_fn, cpu_coregroup_mask); cpumask_andnot(*mask, *mask, submask_fn(i)); } else { cpumask_andnot(*mask, *mask, cpu_coregroup_mask(i)); } } } static void add_cpu_to_masks(int cpu) { struct cpumask *(*submask_fn)(int) = cpu_sibling_mask; int first_thread = cpu_first_thread_sibling(cpu); cpumask_var_t mask; int chip_id = -1; bool ret; int i; /* * This CPU will not be in the online mask yet so we need to manually * add it to it's own thread sibling mask. */ map_cpu_to_node(cpu, cpu_to_node(cpu)); cpumask_set_cpu(cpu, cpu_sibling_mask(cpu)); cpumask_set_cpu(cpu, cpu_core_mask(cpu)); for (i = first_thread; i < first_thread + threads_per_core; i++) if (cpu_online(i)) set_cpus_related(i, cpu, cpu_sibling_mask); add_cpu_to_smallcore_masks(cpu); /* In CPU-hotplug path, hence use GFP_ATOMIC */ ret = alloc_cpumask_var_node(&mask, GFP_ATOMIC, cpu_to_node(cpu)); update_mask_by_l2(cpu, &mask); if (has_coregroup_support()) update_coregroup_mask(cpu, &mask); if (chip_id_lookup_table && ret) chip_id = cpu_to_chip_id(cpu); if (shared_caches) submask_fn = cpu_l2_cache_mask; /* Update core_mask with all the CPUs that are part of submask */ or_cpumasks_related(cpu, cpu, submask_fn, cpu_core_mask); /* Skip all CPUs already part of current CPU core mask */ cpumask_andnot(mask, cpu_online_mask, cpu_core_mask(cpu)); /* If chip_id is -1; limit the cpu_core_mask to within DIE*/ if (chip_id == -1) cpumask_and(mask, mask, cpu_cpu_mask(cpu)); for_each_cpu(i, mask) { if (chip_id == cpu_to_chip_id(i)) { or_cpumasks_related(cpu, i, submask_fn, cpu_core_mask); cpumask_andnot(mask, mask, submask_fn(i)); } else { cpumask_andnot(mask, mask, cpu_core_mask(i)); } } free_cpumask_var(mask); } /* Activate a secondary processor. */ __no_stack_protector void start_secondary(void *unused) { unsigned int cpu = raw_smp_processor_id(); /* PPC64 calls setup_kup() in early_setup_secondary() */ if (IS_ENABLED(CONFIG_PPC32)) setup_kup(); mmgrab_lazy_tlb(&init_mm); current->active_mm = &init_mm; smp_store_cpu_info(cpu); set_dec(tb_ticks_per_jiffy); rcu_cpu_starting(cpu); cpu_callin_map[cpu] = 1; if (smp_ops->setup_cpu) smp_ops->setup_cpu(cpu); if (smp_ops->take_timebase) smp_ops->take_timebase(); secondary_cpu_time_init(); #ifdef CONFIG_PPC64 if (system_state == SYSTEM_RUNNING) vdso_data->processorCount++; vdso_getcpu_init(); #endif set_numa_node(numa_cpu_lookup_table[cpu]); set_numa_mem(local_memory_node(numa_cpu_lookup_table[cpu])); /* Update topology CPU masks */ add_cpu_to_masks(cpu); /* * Check for any shared caches. Note that this must be done on a * per-core basis because one core in the pair might be disabled. */ if (!shared_caches) { struct cpumask *(*sibling_mask)(int) = cpu_sibling_mask; struct cpumask *mask = cpu_l2_cache_mask(cpu); if (has_big_cores) sibling_mask = cpu_smallcore_mask; if (cpumask_weight(mask) > cpumask_weight(sibling_mask(cpu))) shared_caches = true; } smp_wmb(); notify_cpu_starting(cpu); set_cpu_online(cpu, true); boot_init_stack_canary(); local_irq_enable(); /* We can enable ftrace for secondary cpus now */ this_cpu_enable_ftrace(); cpu_startup_entry(CPUHP_AP_ONLINE_IDLE); BUG(); } static void __init fixup_topology(void) { int i; #ifdef CONFIG_SCHED_SMT if (has_big_cores) { pr_info("Big cores detected but using small core scheduling\n"); powerpc_topology[smt_idx].mask = smallcore_smt_mask; } #endif if (!has_coregroup_support()) powerpc_topology[mc_idx].mask = powerpc_topology[cache_idx].mask; /* * Try to consolidate topology levels here instead of * allowing scheduler to degenerate. * - Dont consolidate if masks are different. * - Dont consolidate if sd_flags exists and are different. */ for (i = 1; i <= die_idx; i++) { if (powerpc_topology[i].mask != powerpc_topology[i - 1].mask) continue; if (powerpc_topology[i].sd_flags && powerpc_topology[i - 1].sd_flags && powerpc_topology[i].sd_flags != powerpc_topology[i - 1].sd_flags) continue; if (!powerpc_topology[i - 1].sd_flags) powerpc_topology[i - 1].sd_flags = powerpc_topology[i].sd_flags; powerpc_topology[i].mask = powerpc_topology[i + 1].mask; powerpc_topology[i].sd_flags = powerpc_topology[i + 1].sd_flags; #ifdef CONFIG_SCHED_DEBUG powerpc_topology[i].name = powerpc_topology[i + 1].name; #endif } } void __init smp_cpus_done(unsigned int max_cpus) { /* * We are running pinned to the boot CPU, see rest_init(). */ if (smp_ops && smp_ops->setup_cpu) smp_ops->setup_cpu(boot_cpuid); if (smp_ops && smp_ops->bringup_done) smp_ops->bringup_done(); dump_numa_cpu_topology(); fixup_topology(); set_sched_topology(powerpc_topology); } #ifdef CONFIG_HOTPLUG_CPU int __cpu_disable(void) { int cpu = smp_processor_id(); int err; if (!smp_ops->cpu_disable) return -ENOSYS; this_cpu_disable_ftrace(); err = smp_ops->cpu_disable(); if (err) return err; /* Update sibling maps */ remove_cpu_from_masks(cpu); return 0; } void __cpu_die(unsigned int cpu) { if (smp_ops->cpu_die) smp_ops->cpu_die(cpu); } void __noreturn arch_cpu_idle_dead(void) { /* * Disable on the down path. This will be re-enabled by * start_secondary() via start_secondary_resume() below */ this_cpu_disable_ftrace(); if (smp_ops->cpu_offline_self) smp_ops->cpu_offline_self(); /* If we return, we re-enter start_secondary */ start_secondary_resume(); } #endif