linux/arch/arm/kernel/smp.c
Russell King 573619d165 ARM: SMP: wait for CPU to be marked active
When we bring a CPU online, we should wait for it to become active
before entering the idle thread, so we know that the scheduler and
thread migration is going to work.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-06-21 11:09:05 +01:00

630 lines
14 KiB
C

/*
* linux/arch/arm/kernel/smp.c
*
* Copyright (C) 2002 ARM Limited, All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/cache.h>
#include <linux/profile.h>
#include <linux/errno.h>
#include <linux/ftrace.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/percpu.h>
#include <linux/clockchips.h>
#include <linux/completion.h>
#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/processor.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/localtimer.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_TIMER = 2,
IPI_RESCHEDULE,
IPI_CALL_FUNC,
IPI_CALL_FUNC_SINGLE,
IPI_CPU_STOP,
};
int __cpuinit __cpu_up(unsigned int cpu)
{
struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
struct task_struct *idle = ci->idle;
pgd_t *pgd;
int ret;
/*
* Spawn a new process manually, if not already done.
* Grab a pointer to its task struct so we can mess with it
*/
if (!idle) {
idle = fork_idle(cpu);
if (IS_ERR(idle)) {
printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
return PTR_ERR(idle);
}
ci->idle = idle;
} else {
/*
* Since this idle thread is being re-used, call
* init_idle() to reinitialize the thread structure.
*/
init_idle(idle, cpu);
}
/*
* Allocate initial page tables to allow the new CPU to
* enable the MMU safely. This essentially means a set
* of our "standard" page tables, with the addition of
* a 1:1 mapping for the physical address of the kernel.
*/
pgd = pgd_alloc(&init_mm);
if (!pgd)
return -ENOMEM;
if (PHYS_OFFSET != PAGE_OFFSET) {
#ifndef CONFIG_HOTPLUG_CPU
identity_mapping_add(pgd, __pa(__init_begin), __pa(__init_end));
#endif
identity_mapping_add(pgd, __pa(_stext), __pa(_etext));
identity_mapping_add(pgd, __pa(_sdata), __pa(_edata));
}
/*
* 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;
secondary_data.pgdir = virt_to_phys(pgd);
secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
__cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));
/*
* Now bring the CPU into our world.
*/
ret = boot_secondary(cpu, idle);
if (ret == 0) {
unsigned long timeout;
/*
* CPU was successfully started, wait for it
* to come online or time out.
*/
timeout = jiffies + HZ;
while (time_before(jiffies, timeout)) {
if (cpu_online(cpu))
break;
udelay(10);
barrier();
}
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);
}
secondary_data.stack = NULL;
secondary_data.pgdir = 0;
if (PHYS_OFFSET != PAGE_OFFSET) {
#ifndef CONFIG_HOTPLUG_CPU
identity_mapping_del(pgd, __pa(__init_begin), __pa(__init_end));
#endif
identity_mapping_del(pgd, __pa(_stext), __pa(_etext));
identity_mapping_del(pgd, __pa(_sdata), __pa(_edata));
}
pgd_free(&init_mm, pgd);
return ret;
}
#ifdef CONFIG_HOTPLUG_CPU
static void percpu_timer_stop(void);
/*
* __cpu_disable runs on the processor to be shutdown.
*/
int __cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
struct task_struct *p;
int ret;
ret = platform_cpu_disable(cpu);
if (ret)
return ret;
/*
* Take this CPU offline. Once we clear this, we can't return,
* and we must not schedule until we're ready to give up the cpu.
*/
set_cpu_online(cpu, false);
/*
* OK - migrate IRQs away from this CPU
*/
migrate_irqs();
/*
* Stop the local timer for this CPU.
*/
percpu_timer_stop();
/*
* Flush user cache and TLB mappings, and then remove this CPU
* from the vm mask set of all processes.
*/
flush_cache_all();
local_flush_tlb_all();
read_lock(&tasklist_lock);
for_each_process(p) {
if (p->mm)
cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
}
read_unlock(&tasklist_lock);
return 0;
}
static DECLARE_COMPLETION(cpu_died);
/*
* called on the thread which is asking for a CPU to be shutdown -
* waits until shutdown has completed, or it is timed out.
*/
void __cpu_die(unsigned int cpu)
{
if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
pr_err("CPU%u: cpu didn't die\n", cpu);
return;
}
printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
if (!platform_cpu_kill(cpu))
printk("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 __ref cpu_die(void)
{
unsigned int cpu = smp_processor_id();
idle_task_exit();
local_irq_disable();
mb();
/* Tell __cpu_die() that this CPU is now safe to dispose of */
complete(&cpu_died);
/*
* actual CPU shutdown procedure is at least platform (if not
* CPU) specific.
*/
platform_cpu_die(cpu);
/*
* Do not return to the idle loop - jump back to the secondary
* cpu initialisation. There's some initialisation which needs
* to be repeated to undo the effects of taking the CPU offline.
*/
__asm__("mov sp, %0\n"
" mov fp, #0\n"
" b secondary_start_kernel"
:
: "r" (task_stack_page(current) + THREAD_SIZE - 8));
}
#endif /* CONFIG_HOTPLUG_CPU */
/*
* Called by both boot and secondaries to move global data into
* per-processor storage.
*/
static void __cpuinit 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;
}
/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
*/
asmlinkage void __cpuinit secondary_start_kernel(void)
{
struct mm_struct *mm = &init_mm;
unsigned int cpu = smp_processor_id();
printk("CPU%u: Booted secondary processor\n", cpu);
/*
* All kernel threads share the same mm context; grab a
* reference and switch to it.
*/
atomic_inc(&mm->mm_count);
current->active_mm = mm;
cpumask_set_cpu(cpu, mm_cpumask(mm));
cpu_switch_mm(mm->pgd, mm);
enter_lazy_tlb(mm, current);
local_flush_tlb_all();
cpu_init();
preempt_disable();
trace_hardirqs_off();
/*
* Give the platform a chance to do its own initialisation.
*/
platform_secondary_init(cpu);
/*
* Enable local interrupts.
*/
notify_cpu_starting(cpu);
local_irq_enable();
local_fiq_enable();
/*
* Setup the percpu timer for this CPU.
*/
percpu_timer_setup();
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.
*/
set_cpu_online(cpu, true);
while (!cpu_active(cpu))
cpu_relax();
/*
* OK, it's off to the idle thread for us
*/
cpu_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);
}
void __init smp_prepare_boot_cpu(void)
{
unsigned int cpu = smp_processor_id();
per_cpu(cpu_data, cpu).idle = current;
}
void __init smp_prepare_cpus(unsigned int max_cpus)
{
unsigned int ncores = num_possible_cpus();
smp_store_cpu_info(smp_processor_id());
/*
* are we trying to boot more cores than exist?
*/
if (max_cpus > ncores)
max_cpus = ncores;
if (max_cpus > 1) {
/*
* Enable the local timer or broadcast device for the
* boot CPU, but only if we have more than one CPU.
*/
percpu_timer_setup();
/*
* Initialise the SCU if there are more than one CPU
* and let them know where to start.
*/
platform_smp_prepare_cpus(max_cpus);
}
}
static void (*smp_cross_call)(const struct cpumask *, unsigned int);
void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
{
smp_cross_call = fn;
}
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_SINGLE);
}
static const char *ipi_types[NR_IPI] = {
#define S(x,s) [x - IPI_TIMER] = s
S(IPI_TIMER, "Timer broadcast interrupts"),
S(IPI_RESCHEDULE, "Rescheduling interrupts"),
S(IPI_CALL_FUNC, "Function call interrupts"),
S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
S(IPI_CPU_STOP, "CPU stop interrupts"),
};
void show_ipi_list(struct seq_file *p, int prec)
{
unsigned int cpu, i;
for (i = 0; i < NR_IPI; i++) {
seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
for_each_present_cpu(cpu)
seq_printf(p, "%10u ",
__get_irq_stat(cpu, ipi_irqs[i]));
seq_printf(p, " %s\n", ipi_types[i]);
}
}
u64 smp_irq_stat_cpu(unsigned int cpu)
{
u64 sum = 0;
int i;
for (i = 0; i < NR_IPI; i++)
sum += __get_irq_stat(cpu, ipi_irqs[i]);
#ifdef CONFIG_LOCAL_TIMERS
sum += __get_irq_stat(cpu, local_timer_irqs);
#endif
return sum;
}
/*
* Timer (local or broadcast) support
*/
static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);
static void ipi_timer(void)
{
struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
irq_enter();
evt->event_handler(evt);
irq_exit();
}
#ifdef CONFIG_LOCAL_TIMERS
asmlinkage void __exception_irq_entry do_local_timer(struct pt_regs *regs)
{
struct pt_regs *old_regs = set_irq_regs(regs);
int cpu = smp_processor_id();
if (local_timer_ack()) {
__inc_irq_stat(cpu, local_timer_irqs);
ipi_timer();
}
set_irq_regs(old_regs);
}
void show_local_irqs(struct seq_file *p, int prec)
{
unsigned int cpu;
seq_printf(p, "%*s: ", prec, "LOC");
for_each_present_cpu(cpu)
seq_printf(p, "%10u ", __get_irq_stat(cpu, local_timer_irqs));
seq_printf(p, " Local timer interrupts\n");
}
#endif
#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
static void smp_timer_broadcast(const struct cpumask *mask)
{
smp_cross_call(mask, IPI_TIMER);
}
#else
#define smp_timer_broadcast NULL
#endif
static void broadcast_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
}
static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
{
evt->name = "dummy_timer";
evt->features = CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_DUMMY;
evt->rating = 400;
evt->mult = 1;
evt->set_mode = broadcast_timer_set_mode;
clockevents_register_device(evt);
}
void __cpuinit percpu_timer_setup(void)
{
unsigned int cpu = smp_processor_id();
struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
evt->cpumask = cpumask_of(cpu);
evt->broadcast = smp_timer_broadcast;
if (local_timer_setup(evt))
broadcast_timer_setup(evt);
}
#ifdef CONFIG_HOTPLUG_CPU
/*
* The generic clock events code purposely does not stop the local timer
* on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
* manually here.
*/
static void percpu_timer_stop(void)
{
unsigned int cpu = smp_processor_id();
struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
}
#endif
static DEFINE_SPINLOCK(stop_lock);
/*
* ipi_cpu_stop - handle IPI from smp_send_stop()
*/
static void ipi_cpu_stop(unsigned int cpu)
{
if (system_state == SYSTEM_BOOTING ||
system_state == SYSTEM_RUNNING) {
spin_lock(&stop_lock);
printk(KERN_CRIT "CPU%u: stopping\n", cpu);
dump_stack();
spin_unlock(&stop_lock);
}
set_cpu_online(cpu, false);
local_fiq_disable();
local_irq_disable();
while (1)
cpu_relax();
}
/*
* Main handler for inter-processor interrupts
*/
asmlinkage void __exception_irq_entry do_IPI(int ipinr, struct pt_regs *regs)
{
unsigned int cpu = smp_processor_id();
struct pt_regs *old_regs = set_irq_regs(regs);
if (ipinr >= IPI_TIMER && ipinr < IPI_TIMER + NR_IPI)
__inc_irq_stat(cpu, ipi_irqs[ipinr - IPI_TIMER]);
switch (ipinr) {
case IPI_TIMER:
ipi_timer();
break;
case IPI_RESCHEDULE:
scheduler_ipi();
break;
case IPI_CALL_FUNC:
generic_smp_call_function_interrupt();
break;
case IPI_CALL_FUNC_SINGLE:
generic_smp_call_function_single_interrupt();
break;
case IPI_CPU_STOP:
ipi_cpu_stop(cpu);
break;
default:
printk(KERN_CRIT "CPU%u: Unknown IPI message 0x%x\n",
cpu, ipinr);
break;
}
set_irq_regs(old_regs);
}
void smp_send_reschedule(int cpu)
{
smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
}
void smp_send_stop(void)
{
unsigned long timeout;
if (num_online_cpus() > 1) {
cpumask_t mask = cpu_online_map;
cpu_clear(smp_processor_id(), 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_warning("SMP: failed to stop secondary CPUs\n");
}
/*
* not supported here
*/
int setup_profiling_timer(unsigned int multiplier)
{
return -EINVAL;
}