summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/Kconfig7
-rw-r--r--arch/arm/kernel/irq.c31
-rw-r--r--arch/arm/kernel/process.c9
-rw-r--r--arch/arm/kernel/smp.c109
-rw-r--r--arch/arm/mach-realview/realview_eb.c44
-rw-r--r--arch/arm/mm/init.c9
6 files changed, 192 insertions, 17 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index dc6d8342e5e6..6b12d71978de 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -349,6 +349,13 @@ config NR_CPUS
depends on SMP
default "4"
+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.
+
config PREEMPT
bool "Preemptible Kernel (EXPERIMENTAL)"
depends on EXPERIMENTAL
diff --git a/arch/arm/kernel/irq.c b/arch/arm/kernel/irq.c
index 3284118f356b..9def4404e1f2 100644
--- a/arch/arm/kernel/irq.c
+++ b/arch/arm/kernel/irq.c
@@ -1050,3 +1050,34 @@ static int __init noirqdebug_setup(char *str)
}
__setup("noirqdebug", noirqdebug_setup);
+
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * 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)
+{
+ unsigned int i, cpu = smp_processor_id();
+
+ for (i = 0; i < NR_IRQS; i++) {
+ struct irqdesc *desc = irq_desc + i;
+
+ if (desc->cpu == cpu) {
+ unsigned int newcpu = any_online_cpu(desc->affinity);
+
+ if (newcpu == NR_CPUS) {
+ if (printk_ratelimit())
+ printk(KERN_INFO "IRQ%u no longer affine to CPU%u\n",
+ i, cpu);
+
+ cpus_setall(desc->affinity);
+ newcpu = any_online_cpu(desc->affinity);
+ }
+
+ route_irq(desc, i, newcpu);
+ }
+ }
+}
+#endif /* CONFIG_HOTPLUG_CPU */
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 409db6d5ec99..ba298277becd 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -26,6 +26,7 @@
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/init.h>
+#include <linux/cpu.h>
#include <asm/system.h>
#include <asm/io.h>
@@ -105,6 +106,14 @@ void cpu_idle(void)
/* endless idle loop with no priority at all */
while (1) {
void (*idle)(void) = pm_idle;
+
+#ifdef CONFIG_HOTPLUG_CPU
+ if (cpu_is_offline(smp_processor_id())) {
+ leds_event(led_idle_start);
+ cpu_die();
+ }
+#endif
+
if (!idle)
idle = default_idle;
preempt_disable();
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 826164945747..edb5a406922f 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -80,19 +80,23 @@ static DEFINE_SPINLOCK(smp_call_function_lock);
int __cpuinit __cpu_up(unsigned int cpu)
{
- struct task_struct *idle;
+ struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
+ struct task_struct *idle = ci->idle;
pgd_t *pgd;
pmd_t *pmd;
int ret;
/*
- * Spawn a new process manually. Grab a pointer to
- * its task struct so we can mess with it
+ * Spawn a new process manually, if not already done.
+ * Grab a pointer to its task struct so we can mess with it
*/
- idle = fork_idle(cpu);
- if (IS_ERR(idle)) {
- printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
- return PTR_ERR(idle);
+ 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;
}
/*
@@ -155,6 +159,91 @@ int __cpuinit __cpu_up(unsigned int cpu)
return ret;
}
+#ifdef CONFIG_HOTPLUG_CPU
+/*
+ * __cpu_disable runs on the processor to be shutdown.
+ */
+int __cpuexit __cpu_disable(void)
+{
+ unsigned int cpu = smp_processor_id();
+ struct task_struct *p;
+ int ret;
+
+ ret = mach_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.
+ */
+ cpu_clear(cpu, cpu_online_map);
+
+ /*
+ * OK - migrate IRQs away from this CPU
+ */
+ migrate_irqs();
+
+ /*
+ * 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)
+ cpu_clear(cpu, p->mm->cpu_vm_mask);
+ }
+ read_unlock(&tasklist_lock);
+
+ return 0;
+}
+
+/*
+ * called on the thread which is asking for a CPU to be shutdown -
+ * waits until shutdown has completed, or it is timed out.
+ */
+void __cpuexit __cpu_die(unsigned int 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 __cpuexit cpu_die(void)
+{
+ unsigned int cpu = smp_processor_id();
+
+ local_irq_disable();
+ idle_task_exit();
+
+ /*
+ * 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"
+ " b secondary_start_kernel"
+ :
+ : "r" ((void *)current->thread_info + THREAD_SIZE - 8));
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
/*
* This is the secondary CPU boot entry. We're using this CPUs
* idle thread stack, but a set of temporary page tables.
@@ -236,6 +325,8 @@ void __init smp_prepare_boot_cpu(void)
{
unsigned int cpu = smp_processor_id();
+ per_cpu(cpu_data, cpu).idle = current;
+
cpu_set(cpu, cpu_possible_map);
cpu_set(cpu, cpu_present_map);
cpu_set(cpu, cpu_online_map);
@@ -309,8 +400,8 @@ int smp_call_function_on_cpu(void (*func)(void *info), void *info, int retry,
printk(KERN_CRIT
"CPU%u: smp_call_function timeout for %p(%p)\n"
" callmap %lx pending %lx, %swait\n",
- smp_processor_id(), func, info, callmap, data.pending,
- wait ? "" : "no ");
+ smp_processor_id(), func, info, *cpus_addr(callmap),
+ *cpus_addr(data.pending), wait ? "" : "no ");
/*
* TRACE
diff --git a/arch/arm/mach-realview/realview_eb.c b/arch/arm/mach-realview/realview_eb.c
index 01b264be5029..267bb07e39b7 100644
--- a/arch/arm/mach-realview/realview_eb.c
+++ b/arch/arm/mach-realview/realview_eb.c
@@ -43,14 +43,44 @@
#include "clock.h"
static struct map_desc realview_eb_io_desc[] __initdata = {
- { IO_ADDRESS(REALVIEW_SYS_BASE), REALVIEW_SYS_BASE, SZ_4K, MT_DEVICE },
- { IO_ADDRESS(REALVIEW_GIC_CPU_BASE), REALVIEW_GIC_CPU_BASE, SZ_4K, MT_DEVICE },
- { IO_ADDRESS(REALVIEW_GIC_DIST_BASE), REALVIEW_GIC_DIST_BASE, SZ_4K, MT_DEVICE },
- { IO_ADDRESS(REALVIEW_SCTL_BASE), REALVIEW_SCTL_BASE, SZ_4K, MT_DEVICE },
- { IO_ADDRESS(REALVIEW_TIMER0_1_BASE), REALVIEW_TIMER0_1_BASE, SZ_4K, MT_DEVICE },
- { IO_ADDRESS(REALVIEW_TIMER2_3_BASE), REALVIEW_TIMER2_3_BASE, SZ_4K, MT_DEVICE },
+ {
+ .virtual = IO_ADDRESS(REALVIEW_SYS_BASE),
+ .pfn = __phys_to_pfn(REALVIEW_SYS_BASE),
+ .length = SZ_4K,
+ .type = MT_DEVICE,
+ }, {
+ .virtual = IO_ADDRESS(REALVIEW_GIC_CPU_BASE),
+ .pfn = __phys_to_pfn(REALVIEW_GIC_CPU_BASE),
+ .length = SZ_4K,
+ .type = MT_DEVICE,
+ }, {
+ .virtual = IO_ADDRESS(REALVIEW_GIC_DIST_BASE),
+ .pfn = __phys_to_pfn(REALVIEW_GIC_DIST_BASE),
+ .length = SZ_4K,
+ .type = MT_DEVICE,
+ }, {
+ .virtual = IO_ADDRESS(REALVIEW_SCTL_BASE),
+ .pfn = __phys_to_pfn(REALVIEW_SCTL_BASE),
+ .length = SZ_4K,
+ .type = MT_DEVICE,
+ }, {
+ .virtual = IO_ADDRESS(REALVIEW_TIMER0_1_BASE),
+ .pfn = __phys_to_pfn(REALVIEW_TIMER0_1_BASE),
+ .length = SZ_4K,
+ .type = MT_DEVICE,
+ }, {
+ .virtual = IO_ADDRESS(REALVIEW_TIMER2_3_BASE),
+ .pfn = __phys_to_pfn(REALVIEW_TIMER2_3_BASE),
+ .length = SZ_4K,
+ .type = MT_DEVICE,
+ },
#ifdef CONFIG_DEBUG_LL
- { IO_ADDRESS(REALVIEW_UART0_BASE), REALVIEW_UART0_BASE, SZ_4K, MT_DEVICE },
+ {
+ .virtual = IO_ADDRESS(REALVIEW_UART0_BASE),
+ .pfn = __phys_to_pfn(REALVIEW_UART0_BASE),
+ .length = SZ_4K,
+ .type = MT_DEVICE,
+ }
#endif
};
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index fd079ff1fc53..c168f322ef8c 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -486,10 +486,17 @@ static void __init devicemaps_init(struct machine_desc *mdesc)
/*
* Ask the machine support to map in the statically mapped devices.
- * After this point, we can start to touch devices again.
*/
if (mdesc->map_io)
mdesc->map_io();
+
+ /*
+ * Finally flush the tlb again - this ensures that we're in a
+ * consistent state wrt the writebuffer if the writebuffer needs
+ * draining. After this point, we can start to touch devices
+ * again.
+ */
+ local_flush_tlb_all();
}
/*