Commit 763142d1 authored by Paul Mundt's avatar Paul Mundt
Browse files

sh: CPU hotplug support.



This adds preliminary support for CPU hotplug for SH SMP systems.
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 8db2bc45
......@@ -706,6 +706,13 @@ config NR_CPUS
This is purely to save memory - each supported CPU adds
approximately eight kilobytes to the kernel image.
config HOTPLUG_CPU
bool "Support for hot-pluggable CPUs (EXPERIMENTAL)"
depends on SMP && HOTPLUG && EXPERIMENTAL
help
Say Y here to experiment with turning CPUs off and on. CPUs
can be controlled through /sys/devices/system/cpu.
source "kernel/Kconfig.preempt"
config GUSA
......
#ifndef __ASM_SH_IRQ_H
#define __ASM_SH_IRQ_H
#include <linux/cpumask.h>
#include <asm/machvec.h>
/*
......@@ -50,6 +51,8 @@ static inline int generic_irq_demux(int irq)
#define irq_demux(irq) sh_mv.mv_irq_demux(irq)
void init_IRQ(void);
void migrate_irqs(void);
asmlinkage int do_IRQ(unsigned int irq, struct pt_regs *regs);
#ifdef CONFIG_IRQSTACKS
......
......@@ -7,20 +7,27 @@ struct plat_smp_ops {
void (*prepare_cpus)(unsigned int max_cpus);
void (*start_cpu)(unsigned int cpu, unsigned long entry_point);
void (*send_ipi)(unsigned int cpu, unsigned int message);
int (*cpu_disable)(unsigned int cpu);
void (*cpu_die)(unsigned int cpu);
void (*play_dead)(void);
};
extern struct plat_smp_ops *mp_ops;
extern struct plat_smp_ops shx3_smp_ops;
#ifdef CONFIG_SMP
static inline void plat_smp_setup(void)
{
extern struct plat_smp_ops *mp_ops; /* private */
BUG_ON(!mp_ops);
mp_ops->smp_setup();
}
static inline void play_dead(void)
{
mp_ops->play_dead();
}
extern void register_smp_ops(struct plat_smp_ops *ops);
#else
......@@ -34,6 +41,11 @@ static inline void register_smp_ops(struct plat_smp_ops *ops)
{
}
static inline void play_dead(void)
{
BUG();
}
#endif /* CONFIG_SMP */
#endif /* __ASM_SH_SMP_OPS_H */
......@@ -38,9 +38,26 @@ void smp_timer_broadcast(const struct cpumask *mask);
void local_timer_interrupt(void);
void local_timer_setup(unsigned int cpu);
void local_timer_stop(unsigned int cpu);
void arch_send_call_function_single_ipi(int cpu);
extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);
void arch_send_call_function_ipi_mask(const struct cpumask *mask);
void native_play_dead(void);
void native_cpu_die(unsigned int cpu);
int native_cpu_disable(unsigned int cpu);
#ifdef CONFIG_HOTPLUG_CPU
void play_dead_common(void);
extern int __cpu_disable(void);
static inline void __cpu_die(unsigned int cpu)
{
extern struct plat_smp_ops *mp_ops; /* private */
mp_ops->cpu_die(cpu);
}
#endif
static inline int hard_smp_processor_id(void)
{
......
......@@ -19,6 +19,7 @@
#include <asm/pgalloc.h>
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/smp.h>
void (*pm_idle)(void) = NULL;
......@@ -89,10 +90,13 @@ void cpu_idle(void)
while (1) {
tick_nohz_stop_sched_tick(1);
while (!need_resched() && cpu_online(cpu)) {
while (!need_resched()) {
check_pgt_cache();
rmb();
if (cpu_is_offline(cpu))
play_dead();
local_irq_disable();
/* Don't trace irqs off for idle */
stop_critical_timings();
......
......@@ -12,6 +12,7 @@
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
#include <linux/ftrace.h>
#include <linux/delay.h>
#include <asm/processor.h>
#include <asm/machvec.h>
#include <asm/uaccess.h>
......@@ -292,3 +293,44 @@ int __init arch_probe_nr_irqs(void)
return 0;
}
#endif
#ifdef CONFIG_HOTPLUG_CPU
static void route_irq(struct irq_desc *desc, unsigned int irq, unsigned int cpu)
{
printk(KERN_INFO "IRQ%u: moving from cpu%u to cpu%u\n",
irq, desc->node, cpu);
raw_spin_lock_irq(&desc->lock);
desc->chip->set_affinity(irq, cpumask_of(cpu));
raw_spin_unlock_irq(&desc->lock);
}
/*
* The CPU has been marked offline. Migrate IRQs off this CPU. If
* the affinity settings do not allow other CPUs, force them onto any
* available CPU.
*/
void migrate_irqs(void)
{
struct irq_desc *desc;
unsigned int irq, cpu = smp_processor_id();
for_each_irq_desc(irq, desc) {
if (desc->node == cpu) {
unsigned int newcpu = cpumask_any_and(desc->affinity,
cpu_online_mask);
if (newcpu >= nr_cpu_ids) {
if (printk_ratelimit())
printk(KERN_INFO "IRQ%u no longer affine to CPU%u\n",
irq, cpu);
cpumask_setall(desc->affinity);
newcpu = cpumask_any_and(desc->affinity,
cpu_online_mask);
}
route_irq(desc, irq, newcpu);
}
}
}
#endif
......@@ -60,3 +60,7 @@ void local_timer_setup(unsigned int cpu)
clockevents_register_device(clk);
}
void local_timer_stop(unsigned int cpu)
{
}
......@@ -79,6 +79,105 @@ void __init smp_prepare_boot_cpu(void)
per_cpu(cpu_state, cpu) = CPU_ONLINE;
}
#ifdef CONFIG_HOTPLUG_CPU
void native_cpu_die(unsigned int cpu)
{
unsigned int i;
for (i = 0; i < 10; i++) {
smp_rmb();
if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
if (system_state == SYSTEM_RUNNING)
pr_info("CPU %u is now offline\n", cpu);
return;
}
msleep(100);
}
pr_err("CPU %u didn't die...\n", cpu);
}
int native_cpu_disable(unsigned int cpu)
{
return cpu == 0 ? -EPERM : 0;
}
void play_dead_common(void)
{
idle_task_exit();
irq_ctx_exit(raw_smp_processor_id());
mb();
__get_cpu_var(cpu_state) = CPU_DEAD;
local_irq_disable();
}
void native_play_dead(void)
{
play_dead_common();
}
int __cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
struct task_struct *p;
int ret;
ret = mp_ops->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.
*/
local_timer_stop(cpu);
/*
* 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;
}
#else /* ... !CONFIG_HOTPLUG_CPU */
int native_cpu_disable(void)
{
return -ENOSYS;
}
void native_cpu_die(unsigned int cpu)
{
/* We said "no" in __cpu_disable */
BUG();
}
void native_play_dead(void)
{
BUG();
}
#endif
asmlinkage void __cpuinit start_secondary(void)
{
unsigned int cpu = smp_processor_id();
......@@ -88,8 +187,8 @@ asmlinkage void __cpuinit start_secondary(void)
atomic_inc(&mm->mm_count);
atomic_inc(&mm->mm_users);
current->active_mm = mm;
BUG_ON(current->mm);
enter_lazy_tlb(mm, current);
local_flush_tlb_all();
per_cpu_trap_init();
......@@ -156,6 +255,7 @@ int __cpuinit __cpu_up(unsigned int cpu)
break;
udelay(10);
barrier();
}
if (cpu_online(cpu))
......@@ -270,7 +370,6 @@ static void flush_tlb_mm_ipi(void *mm)
* behalf of debugees, kswapd stealing pages from another process etc).
* Kanoj 07/00.
*/
void flush_tlb_mm(struct mm_struct *mm)
{
preempt_disable();
......
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