// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/arm/kernel/smp.c
*
* Copyright (C) 2002 ARM Limited, All Rights Reserved.
*/
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched/mm.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task_stack.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/err.h>
#include <linux/cpu.h>
#include <linux/seq_file.h>
#include <linux/irq.h>
#include <linux/nmi.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <linux/completion.h>
#include <linux/cpufreq.h>
#include <linux/irq_work.h>
#include <linux/kernel_stat.h>
#include <linux/atomic.h>
#include <asm/bugs.h>
#include <asm/smp.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/exception.h>
#include <asm/idmap.h>
#include <asm/topology.h>
#include <asm/mmu_context.h>
#include <asm/procinfo.h>
#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/smp_plat.h>
#include <asm/virt.h>
#include <asm/mach/arch.h>
#include <asm/mpu.h>
#include <trace/events/ipi.h>
/*
* as from 2.5, kernels no longer have an init_tasks structure
* so we need some other way of telling a new secondary core
* where to place its SVC stack
*/
struct secondary_data secondary_data;
enum ipi_msg_type {
IPI_WAKEUP,
IPI_TIMER,
IPI_RESCHEDULE,
IPI_CALL_FUNC,
IPI_CPU_STOP,
IPI_IRQ_WORK,
IPI_COMPLETION,
NR_IPI,
/*
* CPU_BACKTRACE is special and not included in NR_IPI
* or tracable with trace_ipi_*
*/
IPI_CPU_BACKTRACE = NR_IPI,
/*
* SGI8-15 can be reserved by secure firmware, and thus may
* not be usable by the kernel. Please keep the above limited
* to at most 8 entries.
*/
MAX_IPI
};
static int ipi_irq_base __read_mostly;
static int nr_ipi __read_mostly = NR_IPI;
static struct irq_desc *ipi_desc[MAX_IPI] __read_mostly;
static void ipi_setup(int cpu);
static DECLARE_COMPLETION(cpu_running);
static struct smp_operations smp_ops __ro_after_init;
void __init smp_set_ops(const struct smp_operations *ops)
{
if (ops)
smp_ops = *ops;
};
static unsigned long get_arch_pgd(pgd_t *pgd)
{
#ifdef CONFIG_ARM_LPAE
return __phys_to_pfn(virt_to_phys(pgd));
#else
return virt_to_phys(pgd);
#endif
}
#if defined(CONFIG_BIG_LITTLE) && defined(CONFIG_HARDEN_BRANCH_PREDICTOR)
static int secondary_biglittle_prepare(unsigned int cpu)
{
if (!cpu_vtable[cpu])
cpu_vtable[cpu] = kzalloc(sizeof(*cpu_vtable[cpu]), GFP_KERNEL);
return cpu_vtable[cpu] ? 0 : -ENOMEM;
}
static void secondary_biglittle_init(void)
{
init_proc_vtable(lookup_processor(read_cpuid_id())->proc);
}
#else
static int secondary_biglittle_prepare(unsigned int cpu)
{
return 0;
}
static void secondary_biglittle_init(void)
{
}
#endif
int __cpu_up(unsigned int cpu, struct task_struct *idle)
{
int ret;
if (!smp_ops.smp_boot_secondary)
return -ENOSYS;
ret = secondary_biglittle_prepare(cpu);
if (ret)
return ret;
/*
* We need to tell the secondary core where to find
* its stack and the page tables.
*/
secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
#ifdef CONFIG_ARM_MPU
secondary_data.mpu_rgn_info = &mpu_rgn_info;
#endif
#ifdef CONFIG_MMU
secondary_data.pgdir = virt_to_phys(idmap_pgd);
secondary_data.swapper_pg_dir = get_arch_pgd(swapper_pg_dir);
#endif
secondary_data.task = idle;
sync_cache_w(&secondary_data);
/*
* Now bring the CPU into our world.
*/
ret = smp_ops.smp_boot_secondary(cpu, idle);
if (ret == 0) {
/*
* CPU was successfully started, wait for it
* to come online or time out.
*/
wait_for_completion_timeout(&cpu_running,
msecs_to_jiffies(1000));
if (!cpu_online(cpu)) {
pr_crit("CPU%u: failed to come online\n", cpu);
ret = -EIO;
}
} else {
pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
}
memset(&secondary_data, 0, sizeof(secondary_data));
return ret;
}
/* platform specific SMP operations */
void __init smp_init_cpus(void)
{
if (smp_ops.smp_init_cpus)
smp_ops.smp_init_cpus();
}
int platform_can_secondary_boot(void)
{
return !!smp_ops.smp_boot_secondary;
}
int platform_can_cpu_hotplug(void)
{
#ifdef CONFIG_HOTPLUG_CPU
if (smp_ops.cpu_kill)
return 1;
#endif
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
static int platform_cpu_kill(unsigned int cpu)
{
if (smp_ops.cpu_kill)
return smp_ops.cpu_kill(cpu);
return 1;
}
static int platform_cpu_disable(unsigned int cpu)
{
if (smp_ops.cpu_disable)
return smp_ops.cpu_disable(cpu);
return 0;
}
int platform_can_hotplug_cpu(unsigned int cpu)
{
/* cpu_die must be specified to support hotplug */
if (!smp_ops.cpu_die)
return 0;
if (smp_ops.cpu_can_disable)
return smp_ops.cpu_can_disable(cpu);
/*
* By default, allow disabling all CPUs except the first one,
* since this is special on a lot of platforms, e.g. because
* of clock tick interrupts.
*/
return cpu != 0;
}
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);
}
/*
* __cpu_disable runs on the processor to be shutdown.
*/
int __cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
int ret;
ret = platform_cpu_disable(cpu);
if (ret)
return ret;
#ifdef CONFIG_GENERIC_ARCH_TOPOLOGY
remove_cpu_topology(cpu);
#endif
/*
* Take this CPU offline. Once we clear this, we can't return,
* and we must not schedule until we're ready to give up the cpu.
*/
set_cpu_online(cpu, false);
ipi_teardown(cpu);
/*
* OK - migrate IRQs away from this CPU
*/
irq_migrate_all_off_this_cpu();
/*
* Flush user cache and TLB mappings, and then remove this CPU
* from the vm mask set of all processes.
*
* Caches are flushed to the Level of Unification Inner Shareable
* to write-back dirty lines to unified caches shared by all CPUs.
*/
flush_cache_louis();
local_flush_tlb_all();
return 0;
}
/*
* called on the thread which is asking for a CPU to be shutdown after the
* shutdown completed.
*/
void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)
{
pr_debug("CPU%u: shutdown\n", cpu);
clear_tasks_mm_cpumask(cpu);
/*
* platform_cpu_kill() is generally expected to do the powering off
* and/or cutting of clocks to the dying CPU. Optionally, this may
* be done by the CPU which is dying in preference to supporting
* this call, but that means there is _no_ synchronisation between
* the requesting CPU and the dying CPU actually losing power.
*/
if (!platform_cpu_kill(cpu))
pr_err("CPU%u: unable to kill\n", cpu);
}
/*
* Called from the idle thread for the CPU which has been shutdown.
*
* Note that we disable IRQs here, but do not re-enable them
* before returning to the caller. This is also the behaviour
* of the other hotplug-cpu capable cores, so presumably coming
* out of idle fixes this.
*/
void __noreturn arch_cpu_idle_dead(void)
{
unsigned int cpu = smp_processor_id();
idle_task_exit();
local_irq_disable();
/*
* Flush the data out of the L1 cache for this CPU. This must be
* before the completion to ensure that data is safely written out
* before platform_cpu_kill() gets called - which may disable
* *this* CPU and power down its cache.
*/
flush_cache_louis();
/*
* Tell cpuhp_bp_sync_dead() that this CPU is now safe to dispose
* of. Once this returns, power and/or clocks can be removed at
* any point from this CPU and its cache by platform_cpu_kill().
*/
cpuhp_ap_report_dead();
/*
* Ensure that the cache lines associated with that completion are
* written out. This covers the case where _this_ CPU is doing the
* powering down, to ensure that the completion is visible to the
* CPU waiting for this one.
*/
flush_cache_louis();
/*
* The actual CPU shutdown procedure is at least platform (if not
* CPU) specific. This may remove power, or it may simply spin.
*
* Platforms are generally expected *NOT* to return from this call,
* although there are some which do because they have no way to
* power down the CPU. These platforms are the _only_ reason we
* have a return path which uses the fragment of assembly below.
*
* The return path should not be used for platforms which can
* power off the CPU.
*/
if (smp_ops.cpu_die)
smp_ops.cpu_die(cpu);
pr_warn("CPU%u: smp_ops.cpu_die() returned, trying to resuscitate\n",
cpu);
/*
* Do not return to the idle loop - jump back to the secondary
* cpu initialisation. There's some initialisation which needs
* to be repeated to undo the effects of taking the CPU offline.
*/
__asm__("mov sp, %0\n"
" mov fp, #0\n"
" mov r0, %1\n"
" b secondary_start_kernel"
:
: "r" (task_stack_page(current) + THREAD_SIZE - 8),
"r" (current)
: "r0");
unreachable();
}
#endif /* CONFIG_HOTPLUG_CPU */
/*
* Called by both boot and secondaries to move global data into
* per-processor storage.
*/
static void smp_store_cpu_info(unsigned int cpuid)
{
struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
cpu_info->loops_per_jiffy = loops_per_jiffy;
cpu_info->cpuid = read_cpuid_id();
store_cpu_topology(cpuid);
check_cpu_icache_size(cpuid);
}
static void set_current(struct task_struct *cur)
{
/* Set TPIDRURO */
asm("mcr p15, 0, %0, c13, c0, 3" :: "r"(cur) : "memory");
}
/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
*/
asmlinkage void secondary_start_kernel(struct task_struct *task)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu;
set_current(task);
secondary_biglittle_init();
/*
* The identity mapping is uncached (strongly ordered), so
* switch away from it before attempting any exclusive accesses.
*/
cpu_switch_mm(mm->pgd, mm);
local_flush_bp_all();
enter_lazy_tlb(mm, current);
local_flush_tlb_all();
/*
* All kernel threads share the same mm context; grab a
* reference and switch to it.
*/
cpu = smp_processor_id();
mmgrab(mm);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
cpu_init();
#ifndef CONFIG_MMU
setup_vectors_base();
#endif
pr_debug("CPU%u: Booted secondary processor\n", cpu);
trace_hardirqs_off();
/*
* Give the platform a chance to do its own initialisation.
*/
if (smp_ops.smp_secondary_init)
smp_ops.smp_secondary_init(cpu);
notify_cpu_starting(cpu);
ipi_setup(cpu);
calibrate_delay();
smp_store_cpu_info(cpu);
/*
* OK, now it's safe to let the boot CPU continue. Wait for
* the CPU migration code to notice that the CPU is online
* before we continue - which happens after __cpu_up returns.
*/
set_cpu_online(cpu, true);
check_other_bugs();
complete(&cpu_running);
local_irq_enable();
local_fiq_enable();
local_abt_enable();
/*
* OK, it's off to the idle thread for us
*/
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}
void __init smp_cpus_done(unsigned int max_cpus)
{
int cpu;
unsigned long bogosum = 0;
for_each_online_cpu(cpu)
bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
printk(KERN_INFO "SMP: Total of %d processors activated "
"(%lu.%02lu BogoMIPS).\n",
num_online_cpus(),
bogosum / (500000/HZ),
(bogosum / (5000/HZ)) % 100);
hyp_mode_check();
}
void __init smp_prepare_boot_cpu(void)
{
set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
}
void __init smp_prepare_cpus(unsigned int max_cpus)
{
unsigned int ncores = num_possible_cpus();
init_cpu_topology();
smp_store_cpu_info(smp_processor_id());
/*
* are we trying to boot more cores than exist?
*/
if (max_cpus > ncores)
max_cpus = ncores;
if (ncores > 1 && max_cpus) {
/*
* Initialise the present map, which describes the set of CPUs
* actually populated at the present time. A platform should
* re-initialize the map in the platforms smp_prepare_cpus()
* if present != possible (e.g. physical hotplug).
*/
init_cpu_present(cpu_possible_mask);
/*
* Initialise the SCU if there are more than one CPU
* and let them know where to start.
*/
if (smp_ops.smp_prepare_cpus)
smp_ops.smp_prepare_cpus(max_cpus);
}
}
static const char *ipi_types[NR_IPI] __tracepoint_string = {
[IPI_WAKEUP] = "CPU wakeup interrupts",
[IPI_TIMER] = "Timer broadcast interrupts",
[IPI_RESCHEDULE] = "Rescheduling interrupts",
[IPI_CALL_FUNC] = "Function call interrupts",
[IPI_CPU_STOP] = "CPU stop interrupts",
[IPI_IRQ_WORK] = "IRQ work interrupts",
[IPI_COMPLETION] = "completion interrupts",
};
static void smp_cross_call(const struct cpumask *target, unsigned int ipinr);
void show_ipi_list(struct seq_file *p, int prec)
{
unsigned int cpu, i;
for (i = 0; i < NR_IPI; i++) {
if (!ipi_desc[i])
continue;
seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
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]);
}
}
void arch_send_call_function_ipi_mask(const struct cpumask *mask)
{
smp_cross_call(mask, IPI_CALL_FUNC);
}
void arch_send_wakeup_ipi_mask(const struct cpumask *mask)
{
smp_cross_call(mask, IPI_WAKEUP);
}
void arch_send_call_function_single_ipi(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC);
}
#ifdef CONFIG_IRQ_WORK
void arch_irq_work_raise(void)
{
if (arch_irq_work_has_interrupt())
smp_cross_call(cpumask_of(smp_processor_id()), IPI_IRQ_WORK);
}
#endif
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
void tick_broadcast(const struct cpumask *mask)
{
smp_cross_call(mask, IPI_TIMER);
}
#endif
static DEFINE_RAW_SPINLOCK(stop_lock);
/*
* ipi_cpu_stop - handle IPI from smp_send_stop()
*/
static void ipi_cpu_stop(unsigned int cpu)
{
local_fiq_disable();
if (system_state <= SYSTEM_RUNNING) {
raw_spin_lock(&stop_lock);
pr_crit("CPU%u: stopping\n", cpu);
dump_stack();
raw_spin_unlock(&stop_lock);
}
set_cpu_online(cpu, false);
while (1) {
cpu_relax();
wfe();
}
}
static DEFINE_PER_CPU(struct completion *, cpu_completion);
int register_ipi_completion(struct completion *completion, int cpu)
{
per_cpu(cpu_completion, cpu) = completion;
return IPI_COMPLETION;
}
static void ipi_complete(unsigned int cpu)
{
complete(per_cpu(cpu_completion, cpu));
}
/*
* Main handler for inter-processor interrupts
*/
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_WAKEUP:
break;
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
case IPI_TIMER:
tick_receive_broadcast();
break;
#endif
case IPI_RESCHEDULE:
scheduler_ipi();
break;
case IPI_CALL_FUNC:
generic_smp_call_function_interrupt();
break;
case IPI_CPU_STOP:
ipi_cpu_stop(cpu);
break;
#ifdef CONFIG_IRQ_WORK
case IPI_IRQ_WORK:
irq_work_run();
break;
#endif
case IPI_COMPLETION:
ipi_complete(cpu);
break;
case IPI_CPU_BACKTRACE:
printk_deferred_enter();
nmi_cpu_backtrace(get_irq_regs());
printk_deferred_exit();
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]);
}
/* Legacy version, should go away once all irqchips have been converted */
void handle_IPI(int ipinr, struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
irq_enter();
do_handle_IPI(ipinr);
irq_exit();
set_irq_regs(old_regs);
}
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);
}
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;
err = request_percpu_irq(ipi_base + i, ipi_handler,
"IPI", &irq_stat);
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 arch_smp_send_reschedule(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}
void smp_send_stop(void)
{
unsigned long timeout;
struct cpumask mask;
cpumask_copy(&mask, cpu_online_mask);
cpumask_clear_cpu(smp_processor_id(), &mask);
if (!cpumask_empty(&mask))
smp_cross_call(&mask, IPI_CPU_STOP);
/* Wait up to one second for other CPUs to stop */
timeout = USEC_PER_SEC;
while (num_online_cpus() > 1 && timeout--)
udelay(1);
if (num_online_cpus() > 1)
pr_warn("SMP: failed to stop secondary CPUs\n");
}
/* In case panic() and panic() called at the same time on CPU1 and CPU2,
* and CPU 1 calls panic_smp_self_stop() before crash_smp_send_stop()
* CPU1 can't receive the ipi irqs from CPU2, CPU1 will be always online,
* kdump fails. So split out the panic_smp_self_stop() and add
* set_cpu_online(smp_processor_id(), false).
*/
void __noreturn panic_smp_self_stop(void)
{
pr_debug("CPU %u will stop doing anything useful since another CPU has paniced\n",
smp_processor_id());
set_cpu_online(smp_processor_id(), false);
while (1)
cpu_relax();
}
#ifdef CONFIG_CPU_FREQ
static DEFINE_PER_CPU(unsigned long, l_p_j_ref);
static DEFINE_PER_CPU(unsigned long, l_p_j_ref_freq);
static unsigned long global_l_p_j_ref;
static unsigned long global_l_p_j_ref_freq;
static int cpufreq_callback(struct notifier_block *nb,
unsigned long val, void *data)
{
struct cpufreq_freqs *freq = data;
struct cpumask *cpus = freq->policy->cpus;
int cpu, first = cpumask_first(cpus);
unsigned int lpj;
if (freq->flags & CPUFREQ_CONST_LOOPS)
return NOTIFY_OK;
if (!per_cpu(l_p_j_ref, first)) {
for_each_cpu(cpu, cpus) {
per_cpu(l_p_j_ref, cpu) =
per_cpu(cpu_data, cpu).loops_per_jiffy;
per_cpu(l_p_j_ref_freq, cpu) = freq->old;
}
if (!global_l_p_j_ref) {
global_l_p_j_ref = loops_per_jiffy;
global_l_p_j_ref_freq = freq->old;
}
}
if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
(val == CPUFREQ_POSTCHANGE && freq->old > freq->new)) {
loops_per_jiffy = cpufreq_scale(global_l_p_j_ref,
global_l_p_j_ref_freq,
freq->new);
lpj = cpufreq_scale(per_cpu(l_p_j_ref, first),
per_cpu(l_p_j_ref_freq, first), freq->new);
for_each_cpu(cpu, cpus)
per_cpu(cpu_data, cpu).loops_per_jiffy = lpj;
}
return NOTIFY_OK;
}
static struct notifier_block cpufreq_notifier = {
.notifier_call = cpufreq_callback,
};
static int __init register_cpufreq_notifier(void)
{
return cpufreq_register_notifier(&cpufreq_notifier,
CPUFREQ_TRANSITION_NOTIFIER);
}
core_initcall(register_cpufreq_notifier);
#endif
static void raise_nmi(cpumask_t *mask)
{
__ipi_send_mask(ipi_desc[IPI_CPU_BACKTRACE], mask);
}
void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu)
{
nmi_trigger_cpumask_backtrace(mask, exclude_cpu, raise_nmi);
}
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