Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1131 insertions, 0 deletions

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
new file mode 100644
index 000000000..ae0977b63
--- /dev/null
+++ b/arch/arm64/kernel/smp.c
@@ -0,0 +1,1131 @@
+// 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 <linux/acpi.h>
+#include <linux/arm_sdei.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/smp.h>
+#include <linux/seq_file.h>
+#include <linux/irq.h>
+#include <linux/irqchip/arm-gic-v3.h>
+#include <linux/percpu.h>
+#include <linux/clockchips.h>
+#include <linux/completion.h>
+#include <linux/of.h>
+#include <linux/irq_work.h>
+#include <linux/kernel_stat.h>
+#include <linux/kexec.h>
+#include <linux/kvm_host.h>
+
+#include <asm/alternative.h>
+#include <asm/atomic.h>
+#include <asm/cacheflush.h>
+#include <asm/cpu.h>
+#include <asm/cputype.h>
+#include <asm/cpu_ops.h>
+#include <asm/daifflags.h>
+#include <asm/kvm_mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/numa.h>
+#include <asm/processor.h>
+#include <asm/smp_plat.h>
+#include <asm/sections.h>
+#include <asm/tlbflush.h>
+#include <asm/ptrace.h>
+#include <asm/virt.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/ipi.h>
+
+DEFINE_PER_CPU_READ_MOSTLY(int, cpu_number);
+EXPORT_PER_CPU_SYMBOL(cpu_number);
+
+/*
+ * 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_CRASH_STOP,
+	IPI_TIMER,
+	IPI_IRQ_WORK,
+	IPI_WAKEUP,
+	NR_IPI
+};
+
+static int ipi_irq_base __read_mostly;
+static int nr_ipi __read_mostly = NR_IPI;
+static struct irq_desc *ipi_desc[NR_IPI] __read_mostly;
+
+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;
+	secondary_data.stack = task_stack_page(idle) + THREAD_SIZE;
+	update_cpu_boot_status(CPU_MMU_OFF);
+	__flush_dcache_area(&secondary_data, sizeof(secondary_data));
+
+	/* Now bring the CPU into our world */
+	ret = boot_secondary(cpu, idle);
+	if (ret) {
+		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;
+	secondary_data.stack = NULL;
+	__flush_dcache_area(&secondary_data, sizeof(secondary_data));
+	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));
+
+	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;
+
+	cpu = task_cpu(current);
+	set_my_cpu_offset(per_cpu_offset(cpu));
+
+	/*
+	 * 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();
+
+	rcu_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();
+
+	/*
+	 * Enable GIC and timers.
+	 */
+	notify_cpu_starting(cpu);
+
+	ipi_setup(cpu);
+
+	store_cpu_topology(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);
+
+	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 -
+ * waits until shutdown has completed, or it is timed out.
+ */
+void __cpu_die(unsigned int cpu)
+{
+	int err;
+
+	if (!cpu_wait_death(cpu, 5)) {
+		pr_crit("CPU%u: cpu didn't die\n", cpu);
+		return;
+	}
+	pr_notice("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 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 __cpu_die() that this CPU is now safe to dispose of */
+	(void)cpu_report_death();
+
+	/*
+	 * 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 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);
+	rcu_report_dead(cpu);
+
+	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))
+		kvm_compute_layout();
+}
+
+void __init smp_cpus_done(unsigned int max_cpus)
+{
+	pr_info("SMP: Total of %d processors activated.\n", num_online_cpus());
+	setup_cpu_features();
+	hyp_mode_check();
+	apply_alternatives_all();
+	mark_linear_text_alias_ro();
+}
+
+void __init smp_prepare_boot_cpu(void)
+{
+	set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
+	cpuinfo_store_boot_cpu();
+
+	/*
+	 * We now know enough about the boot CPU to apply the
+	 * alternatives that cannot wait until interrupt handling
+	 * and/or scheduling is enabled.
+	 */
+	apply_boot_alternatives();
+
+	/* Conditionally switch to GIC PMR for interrupt masking */
+	if (system_uses_irq_prio_masking())
+		init_gic_priority_masking();
+}
+
+static u64 __init of_get_cpu_mpidr(struct device_node *dn)
+{
+	const __be32 *cell;
+	u64 hwid;
+
+	/*
+	 * A cpu node with missing "reg" property is
+	 * considered invalid to build a cpu_logical_map
+	 * entry.
+	 */
+	cell = of_get_property(dn, "reg", NULL);
+	if (!cell) {
+		pr_err("%pOF: missing reg property\n", dn);
+		return INVALID_HWID;
+	}
+
+	hwid = of_read_number(cell, of_n_addr_cells(dn));
+	/*
+	 * Non affinity bits must be set to 0 in the DT
+	 */
+	if (hwid & ~MPIDR_HWID_BITMASK) {
+		pr_err("%pOF: invalid reg property\n", dn);
+		return INVALID_HWID;
+	}
+	return hwid;
+}
+
+/*
+ * 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;
+
+#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];
+}
+
+/*
+ * 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)) {
+		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_mpidr(dn);
+
+		if (hwid == INVALID_HWID)
+			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) {
+
+		per_cpu(cpu_number, 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[NR_IPI] __tracepoint_string = {
+#define S(x,s)	[x] = s
+	S(IPI_RESCHEDULE, "Rescheduling interrupts"),
+	S(IPI_CALL_FUNC, "Function call interrupts"),
+	S(IPI_CPU_STOP, "CPU stop interrupts"),
+	S(IPI_CPU_CRASH_STOP, "CPU stop (for crash dump) interrupts"),
+	S(IPI_TIMER, "Timer broadcast interrupts"),
+	S(IPI_IRQ_WORK, "IRQ work interrupts"),
+	S(IPI_WAKEUP, "CPU wake-up 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 < NR_IPI; i++) {
+		unsigned int irq = irq_desc_get_irq(ipi_desc[i]);
+		seq_printf(p, "%*s%u:%s", prec - 1, "IPI", i,
+			   prec >= 4 ? " " : "");
+		for_each_online_cpu(cpu)
+			seq_printf(p, "%10u ", kstat_irqs_cpu(irq, 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_ARM64_ACPI_PARKING_PROTOCOL
+void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
+{
+	smp_cross_call(mask, IPI_WAKEUP);
+}
+#endif
+
+#ifdef CONFIG_IRQ_WORK
+void arch_irq_work_raise(void)
+{
+	smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
+}
+#endif
+
+static void local_cpu_stop(void)
+{
+	set_cpu_online(smp_processor_id(), 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 panic_smp_self_stop(void)
+{
+	local_cpu_stop();
+}
+
+#ifdef CONFIG_KEXEC_CORE
+static atomic_t waiting_for_crash_ipi = ATOMIC_INIT(0);
+#endif
+
+static void ipi_cpu_crash_stop(unsigned int cpu, struct pt_regs *regs)
+{
+#ifdef CONFIG_KEXEC_CORE
+	crash_save_cpu(regs, cpu);
+
+	atomic_dec(&waiting_for_crash_ipi);
+
+	local_irq_disable();
+	sdei_mask_local_cpu();
+
+	if (IS_ENABLED(CONFIG_HOTPLUG_CPU))
+		__cpu_try_die(cpu);
+
+	/* just in case */
+	cpu_park_loop();
+#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_rcuidle(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:
+		local_cpu_stop();
+		break;
+
+	case IPI_CPU_CRASH_STOP:
+		if (IS_ENABLED(CONFIG_KEXEC_CORE)) {
+			ipi_cpu_crash_stop(cpu, get_irq_regs());
+
+			unreachable();
+		}
+		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
+
+#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
+	case IPI_WAKEUP:
+		WARN_ONCE(!acpi_parking_protocol_valid(cpu),
+			  "CPU%u: Wake-up IPI outside the ACPI parking protocol\n",
+			  cpu);
+		break;
+#endif
+
+	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]);
+}
+
+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 void ipi_setup(int cpu)
+{
+	int i;
+
+	if (WARN_ON_ONCE(!ipi_irq_base))
+		return;
+
+	for (i = 0; i < nr_ipi; i++)
+		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++)
+		disable_percpu_irq(ipi_irq_base + i);
+}
+#endif
+
+void __init set_smp_ipi_range(int ipi_base, int n)
+{
+	int i;
+
+	WARN_ON(n < NR_IPI);
+	nr_ipi = min(n, NR_IPI);
+
+	for (i = 0; i < nr_ipi; i++) {
+		int err;
+
+		err = request_percpu_irq(ipi_base + i, ipi_handler,
+					 "IPI", &cpu_number);
+		WARN_ON(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 smp_send_reschedule(int cpu)
+{
+	smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
+}
+
+#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)
+{
+	unsigned long timeout;
+
+	if (num_other_online_cpus()) {
+		cpumask_t mask;
+
+		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");
+		smp_cross_call(&mask, IPI_CPU_STOP);
+	}
+
+	/* Wait up to one second for other CPUs to stop */
+	timeout = USEC_PER_SEC;
+	while (num_other_online_cpus() && timeout--)
+		udelay(1);
+
+	if (num_other_online_cpus())
+		pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
+			cpumask_pr_args(cpu_online_mask));
+
+	sdei_mask_local_cpu();
+}
+
+#ifdef CONFIG_KEXEC_CORE
+void crash_smp_send_stop(void)
+{
+	static int cpus_stopped;
+	cpumask_t mask;
+	unsigned long timeout;
+
+	/*
+	 * This function can be called twice in panic path, but obviously
+	 * we execute this only once.
+	 */
+	if (cpus_stopped)
+		return;
+
+	cpus_stopped = 1;
+
+	/*
+	 * 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;
+
+	cpumask_copy(&mask, cpu_online_mask);
+	cpumask_clear_cpu(smp_processor_id(), &mask);
+
+	atomic_set(&waiting_for_crash_ipi, num_other_online_cpus());
+
+	pr_crit("SMP: stopping secondary CPUs\n");
+	smp_cross_call(&mask, IPI_CPU_CRASH_STOP);
+
+	/* Wait up to one second for other CPUs to stop */
+	timeout = USEC_PER_SEC;
+	while ((atomic_read(&waiting_for_crash_ipi) > 0) && timeout--)
+		udelay(1);
+
+	if (atomic_read(&waiting_for_crash_ipi) > 0)
+		pr_warn("SMP: failed to stop secondary CPUs %*pbl\n",
+			cpumask_pr_args(&mask));
+
+skip_ipi:
+	sdei_mask_local_cpu();
+	sdei_handler_abort();
+}
+
+bool smp_crash_stop_failed(void)
+{
+	return (atomic_read(&waiting_for_crash_ipi) > 0);
+}
+#endif
+
+/*
+ * not supported here
+ */
+int setup_profiling_timer(unsigned int multiplier)
+{
+	return -EINVAL;
+}
+
+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;
+}