![Russell King](/assets/img/avatar_default.png)
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>
630 lines
14 KiB
C
630 lines
14 KiB
C
/*
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* linux/arch/arm/kernel/smp.c
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*
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* Copyright (C) 2002 ARM Limited, All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <linux/cache.h>
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#include <linux/profile.h>
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#include <linux/errno.h>
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#include <linux/ftrace.h>
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#include <linux/mm.h>
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#include <linux/err.h>
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#include <linux/cpu.h>
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#include <linux/smp.h>
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#include <linux/seq_file.h>
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#include <linux/irq.h>
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#include <linux/percpu.h>
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#include <linux/clockchips.h>
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#include <linux/completion.h>
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#include <asm/atomic.h>
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#include <asm/cacheflush.h>
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#include <asm/cpu.h>
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#include <asm/cputype.h>
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#include <asm/mmu_context.h>
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#include <asm/pgtable.h>
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#include <asm/pgalloc.h>
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#include <asm/processor.h>
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#include <asm/sections.h>
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#include <asm/tlbflush.h>
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#include <asm/ptrace.h>
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#include <asm/localtimer.h>
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/*
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* as from 2.5, kernels no longer have an init_tasks structure
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* so we need some other way of telling a new secondary core
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* where to place its SVC stack
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*/
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struct secondary_data secondary_data;
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enum ipi_msg_type {
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IPI_TIMER = 2,
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IPI_RESCHEDULE,
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IPI_CALL_FUNC,
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IPI_CALL_FUNC_SINGLE,
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IPI_CPU_STOP,
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};
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int __cpuinit __cpu_up(unsigned int cpu)
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{
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struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
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struct task_struct *idle = ci->idle;
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pgd_t *pgd;
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int ret;
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/*
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* Spawn a new process manually, if not already done.
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* Grab a pointer to its task struct so we can mess with it
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*/
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if (!idle) {
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idle = fork_idle(cpu);
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if (IS_ERR(idle)) {
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printk(KERN_ERR "CPU%u: fork() failed\n", cpu);
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return PTR_ERR(idle);
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}
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ci->idle = idle;
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} else {
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/*
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* Since this idle thread is being re-used, call
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* init_idle() to reinitialize the thread structure.
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*/
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init_idle(idle, cpu);
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}
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/*
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* Allocate initial page tables to allow the new CPU to
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* enable the MMU safely. This essentially means a set
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* of our "standard" page tables, with the addition of
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* a 1:1 mapping for the physical address of the kernel.
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*/
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pgd = pgd_alloc(&init_mm);
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if (!pgd)
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return -ENOMEM;
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if (PHYS_OFFSET != PAGE_OFFSET) {
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#ifndef CONFIG_HOTPLUG_CPU
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identity_mapping_add(pgd, __pa(__init_begin), __pa(__init_end));
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#endif
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identity_mapping_add(pgd, __pa(_stext), __pa(_etext));
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identity_mapping_add(pgd, __pa(_sdata), __pa(_edata));
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}
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/*
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* We need to tell the secondary core where to find
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* its stack and the page tables.
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*/
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secondary_data.stack = task_stack_page(idle) + THREAD_START_SP;
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secondary_data.pgdir = virt_to_phys(pgd);
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secondary_data.swapper_pg_dir = virt_to_phys(swapper_pg_dir);
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__cpuc_flush_dcache_area(&secondary_data, sizeof(secondary_data));
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outer_clean_range(__pa(&secondary_data), __pa(&secondary_data + 1));
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/*
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* Now bring the CPU into our world.
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*/
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ret = boot_secondary(cpu, idle);
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if (ret == 0) {
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unsigned long timeout;
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/*
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* CPU was successfully started, wait for it
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* to come online or time out.
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*/
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timeout = jiffies + HZ;
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while (time_before(jiffies, timeout)) {
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if (cpu_online(cpu))
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break;
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udelay(10);
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barrier();
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}
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if (!cpu_online(cpu)) {
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pr_crit("CPU%u: failed to come online\n", cpu);
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ret = -EIO;
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}
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} else {
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pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
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}
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secondary_data.stack = NULL;
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secondary_data.pgdir = 0;
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if (PHYS_OFFSET != PAGE_OFFSET) {
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#ifndef CONFIG_HOTPLUG_CPU
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identity_mapping_del(pgd, __pa(__init_begin), __pa(__init_end));
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#endif
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identity_mapping_del(pgd, __pa(_stext), __pa(_etext));
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identity_mapping_del(pgd, __pa(_sdata), __pa(_edata));
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}
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pgd_free(&init_mm, pgd);
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return ret;
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}
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#ifdef CONFIG_HOTPLUG_CPU
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static void percpu_timer_stop(void);
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/*
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* __cpu_disable runs on the processor to be shutdown.
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*/
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int __cpu_disable(void)
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{
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unsigned int cpu = smp_processor_id();
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struct task_struct *p;
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int ret;
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ret = platform_cpu_disable(cpu);
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if (ret)
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return ret;
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/*
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* Take this CPU offline. Once we clear this, we can't return,
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* and we must not schedule until we're ready to give up the cpu.
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*/
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set_cpu_online(cpu, false);
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/*
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* OK - migrate IRQs away from this CPU
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*/
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migrate_irqs();
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/*
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* Stop the local timer for this CPU.
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*/
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percpu_timer_stop();
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/*
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* Flush user cache and TLB mappings, and then remove this CPU
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* from the vm mask set of all processes.
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*/
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flush_cache_all();
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local_flush_tlb_all();
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read_lock(&tasklist_lock);
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for_each_process(p) {
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if (p->mm)
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cpumask_clear_cpu(cpu, mm_cpumask(p->mm));
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}
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read_unlock(&tasklist_lock);
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return 0;
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}
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static DECLARE_COMPLETION(cpu_died);
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/*
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* called on the thread which is asking for a CPU to be shutdown -
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* waits until shutdown has completed, or it is timed out.
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*/
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void __cpu_die(unsigned int cpu)
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{
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if (!wait_for_completion_timeout(&cpu_died, msecs_to_jiffies(5000))) {
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pr_err("CPU%u: cpu didn't die\n", cpu);
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return;
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}
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printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
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if (!platform_cpu_kill(cpu))
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printk("CPU%u: unable to kill\n", cpu);
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}
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/*
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* Called from the idle thread for the CPU which has been shutdown.
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*
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* Note that we disable IRQs here, but do not re-enable them
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* before returning to the caller. This is also the behaviour
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* of the other hotplug-cpu capable cores, so presumably coming
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* out of idle fixes this.
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*/
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void __ref cpu_die(void)
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{
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unsigned int cpu = smp_processor_id();
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idle_task_exit();
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local_irq_disable();
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mb();
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/* Tell __cpu_die() that this CPU is now safe to dispose of */
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complete(&cpu_died);
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/*
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* actual CPU shutdown procedure is at least platform (if not
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* CPU) specific.
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*/
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platform_cpu_die(cpu);
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/*
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* Do not return to the idle loop - jump back to the secondary
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* cpu initialisation. There's some initialisation which needs
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* to be repeated to undo the effects of taking the CPU offline.
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*/
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__asm__("mov sp, %0\n"
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" mov fp, #0\n"
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" b secondary_start_kernel"
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:
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: "r" (task_stack_page(current) + THREAD_SIZE - 8));
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}
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#endif /* CONFIG_HOTPLUG_CPU */
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/*
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* Called by both boot and secondaries to move global data into
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* per-processor storage.
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*/
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static void __cpuinit smp_store_cpu_info(unsigned int cpuid)
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{
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struct cpuinfo_arm *cpu_info = &per_cpu(cpu_data, cpuid);
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cpu_info->loops_per_jiffy = loops_per_jiffy;
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}
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/*
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* This is the secondary CPU boot entry. We're using this CPUs
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* idle thread stack, but a set of temporary page tables.
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*/
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asmlinkage void __cpuinit secondary_start_kernel(void)
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{
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struct mm_struct *mm = &init_mm;
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unsigned int cpu = smp_processor_id();
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printk("CPU%u: Booted secondary processor\n", cpu);
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/*
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* All kernel threads share the same mm context; grab a
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* reference and switch to it.
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*/
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atomic_inc(&mm->mm_count);
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current->active_mm = mm;
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cpumask_set_cpu(cpu, mm_cpumask(mm));
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cpu_switch_mm(mm->pgd, mm);
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enter_lazy_tlb(mm, current);
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local_flush_tlb_all();
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cpu_init();
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preempt_disable();
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trace_hardirqs_off();
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/*
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* Give the platform a chance to do its own initialisation.
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*/
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platform_secondary_init(cpu);
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/*
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* Enable local interrupts.
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*/
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notify_cpu_starting(cpu);
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local_irq_enable();
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local_fiq_enable();
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/*
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* Setup the percpu timer for this CPU.
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*/
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percpu_timer_setup();
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calibrate_delay();
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smp_store_cpu_info(cpu);
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/*
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* OK, now it's safe to let the boot CPU continue. Wait for
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* the CPU migration code to notice that the CPU is online
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* before we continue.
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*/
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set_cpu_online(cpu, true);
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while (!cpu_active(cpu))
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cpu_relax();
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/*
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* OK, it's off to the idle thread for us
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*/
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cpu_idle();
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}
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void __init smp_cpus_done(unsigned int max_cpus)
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{
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int cpu;
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unsigned long bogosum = 0;
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for_each_online_cpu(cpu)
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bogosum += per_cpu(cpu_data, cpu).loops_per_jiffy;
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printk(KERN_INFO "SMP: Total of %d processors activated "
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"(%lu.%02lu BogoMIPS).\n",
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num_online_cpus(),
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bogosum / (500000/HZ),
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(bogosum / (5000/HZ)) % 100);
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}
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void __init smp_prepare_boot_cpu(void)
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{
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unsigned int cpu = smp_processor_id();
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per_cpu(cpu_data, cpu).idle = current;
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}
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void __init smp_prepare_cpus(unsigned int max_cpus)
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{
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unsigned int ncores = num_possible_cpus();
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smp_store_cpu_info(smp_processor_id());
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/*
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* are we trying to boot more cores than exist?
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*/
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if (max_cpus > ncores)
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max_cpus = ncores;
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if (max_cpus > 1) {
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/*
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* Enable the local timer or broadcast device for the
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* boot CPU, but only if we have more than one CPU.
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*/
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percpu_timer_setup();
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/*
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* Initialise the SCU if there are more than one CPU
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* and let them know where to start.
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*/
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platform_smp_prepare_cpus(max_cpus);
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}
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}
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static void (*smp_cross_call)(const struct cpumask *, unsigned int);
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void __init set_smp_cross_call(void (*fn)(const struct cpumask *, unsigned int))
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{
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smp_cross_call = fn;
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}
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void arch_send_call_function_ipi_mask(const struct cpumask *mask)
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{
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smp_cross_call(mask, IPI_CALL_FUNC);
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}
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void arch_send_call_function_single_ipi(int cpu)
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{
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smp_cross_call(cpumask_of(cpu), IPI_CALL_FUNC_SINGLE);
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}
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static const char *ipi_types[NR_IPI] = {
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#define S(x,s) [x - IPI_TIMER] = s
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S(IPI_TIMER, "Timer broadcast interrupts"),
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S(IPI_RESCHEDULE, "Rescheduling interrupts"),
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S(IPI_CALL_FUNC, "Function call interrupts"),
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S(IPI_CALL_FUNC_SINGLE, "Single function call interrupts"),
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S(IPI_CPU_STOP, "CPU stop interrupts"),
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};
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void show_ipi_list(struct seq_file *p, int prec)
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{
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unsigned int cpu, i;
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for (i = 0; i < NR_IPI; i++) {
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seq_printf(p, "%*s%u: ", prec - 1, "IPI", i);
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for_each_present_cpu(cpu)
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seq_printf(p, "%10u ",
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__get_irq_stat(cpu, ipi_irqs[i]));
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seq_printf(p, " %s\n", ipi_types[i]);
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}
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}
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u64 smp_irq_stat_cpu(unsigned int cpu)
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{
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u64 sum = 0;
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int i;
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for (i = 0; i < NR_IPI; i++)
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sum += __get_irq_stat(cpu, ipi_irqs[i]);
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#ifdef CONFIG_LOCAL_TIMERS
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sum += __get_irq_stat(cpu, local_timer_irqs);
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#endif
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return sum;
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}
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/*
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* Timer (local or broadcast) support
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*/
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static DEFINE_PER_CPU(struct clock_event_device, percpu_clockevent);
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static void ipi_timer(void)
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{
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struct clock_event_device *evt = &__get_cpu_var(percpu_clockevent);
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irq_enter();
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evt->event_handler(evt);
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irq_exit();
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}
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#ifdef CONFIG_LOCAL_TIMERS
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asmlinkage void __exception_irq_entry do_local_timer(struct pt_regs *regs)
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{
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struct pt_regs *old_regs = set_irq_regs(regs);
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int cpu = smp_processor_id();
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if (local_timer_ack()) {
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__inc_irq_stat(cpu, local_timer_irqs);
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ipi_timer();
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}
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set_irq_regs(old_regs);
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}
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void show_local_irqs(struct seq_file *p, int prec)
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{
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unsigned int cpu;
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seq_printf(p, "%*s: ", prec, "LOC");
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for_each_present_cpu(cpu)
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seq_printf(p, "%10u ", __get_irq_stat(cpu, local_timer_irqs));
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seq_printf(p, " Local timer interrupts\n");
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}
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#endif
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#ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
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static void smp_timer_broadcast(const struct cpumask *mask)
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{
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smp_cross_call(mask, IPI_TIMER);
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}
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#else
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#define smp_timer_broadcast NULL
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#endif
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static void broadcast_timer_set_mode(enum clock_event_mode mode,
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struct clock_event_device *evt)
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{
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}
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static void __cpuinit broadcast_timer_setup(struct clock_event_device *evt)
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{
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evt->name = "dummy_timer";
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evt->features = CLOCK_EVT_FEAT_ONESHOT |
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CLOCK_EVT_FEAT_PERIODIC |
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CLOCK_EVT_FEAT_DUMMY;
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evt->rating = 400;
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evt->mult = 1;
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evt->set_mode = broadcast_timer_set_mode;
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clockevents_register_device(evt);
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}
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void __cpuinit percpu_timer_setup(void)
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{
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unsigned int cpu = smp_processor_id();
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struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
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evt->cpumask = cpumask_of(cpu);
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evt->broadcast = smp_timer_broadcast;
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if (local_timer_setup(evt))
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broadcast_timer_setup(evt);
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}
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#ifdef CONFIG_HOTPLUG_CPU
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/*
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* The generic clock events code purposely does not stop the local timer
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* on CPU_DEAD/CPU_DEAD_FROZEN hotplug events, so we have to do it
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* manually here.
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*/
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static void percpu_timer_stop(void)
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{
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unsigned int cpu = smp_processor_id();
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struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu);
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evt->set_mode(CLOCK_EVT_MODE_UNUSED, evt);
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}
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#endif
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static DEFINE_SPINLOCK(stop_lock);
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/*
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* ipi_cpu_stop - handle IPI from smp_send_stop()
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*/
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static void ipi_cpu_stop(unsigned int cpu)
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{
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if (system_state == SYSTEM_BOOTING ||
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system_state == SYSTEM_RUNNING) {
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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;
|
|
}
|