forked from Minki/linux
c056718464
Currently we do a spin on secondary cpus when waiting to boot. This theoretically causes issues with power consumption and does cause issues with qemu cycle burning (it starves cpu 0 from actually being able to boot.) This change puts each secondary cpu to sleep if they have a power management unit, then signals them to wake via IPI when its time to boot. If the cpus have no power management unit they will loop as before. Note: The wakeup IPI requires a special interrupt handler as on secondary cpu's the interrupt infrastructure is not yet established. This interrupt handler is set and reset by updating SPR_EVBAR. Signed-off-by: Stafford Horne <shorne@gmail.com>
242 lines
4.9 KiB
C
242 lines
4.9 KiB
C
/*
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* Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
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* Copyright (C) 2017 Stafford Horne <shorne@gmail.com>
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*
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* Based on arm64 and arc implementations
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* Copyright (C) 2013 ARM Ltd.
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* Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
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*
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* This file is licensed under the terms of the GNU General Public License
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* version 2. This program is licensed "as is" without any warranty of any
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* kind, whether express or implied.
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*/
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#include <linux/smp.h>
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#include <linux/cpu.h>
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#include <linux/sched.h>
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#include <linux/irq.h>
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#include <asm/cpuinfo.h>
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#include <asm/mmu_context.h>
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#include <asm/tlbflush.h>
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#include <asm/time.h>
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static void (*smp_cross_call)(const struct cpumask *, unsigned int);
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unsigned long secondary_release = -1;
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struct thread_info *secondary_thread_info;
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enum ipi_msg_type {
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IPI_WAKEUP,
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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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};
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static DEFINE_SPINLOCK(boot_lock);
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static void boot_secondary(unsigned int cpu, struct task_struct *idle)
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{
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/*
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* set synchronisation state between this boot processor
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* and the secondary one
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*/
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spin_lock(&boot_lock);
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secondary_release = cpu;
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smp_cross_call(cpumask_of(cpu), IPI_WAKEUP);
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/*
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* now the secondary core is starting up let it run its
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* calibrations, then wait for it to finish
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*/
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spin_unlock(&boot_lock);
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}
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void __init smp_prepare_boot_cpu(void)
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{
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}
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void __init smp_init_cpus(void)
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{
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int i;
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for (i = 0; i < NR_CPUS; i++)
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set_cpu_possible(i, true);
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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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int i;
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/*
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* Initialise the present map, which describes the set of CPUs
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* actually populated at the present time.
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*/
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for (i = 0; i < max_cpus; i++)
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set_cpu_present(i, true);
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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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}
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static DECLARE_COMPLETION(cpu_running);
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int __cpu_up(unsigned int cpu, struct task_struct *idle)
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{
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if (smp_cross_call == NULL) {
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pr_warn("CPU%u: failed to start, IPI controller missing",
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cpu);
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return -EIO;
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}
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secondary_thread_info = task_thread_info(idle);
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current_pgd[cpu] = init_mm.pgd;
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boot_secondary(cpu, idle);
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if (!wait_for_completion_timeout(&cpu_running,
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msecs_to_jiffies(1000))) {
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pr_crit("CPU%u: failed to start\n", cpu);
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return -EIO;
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}
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return 0;
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}
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asmlinkage __init void 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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/*
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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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pr_info("CPU%u: Booted secondary processor\n", cpu);
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setup_cpuinfo();
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openrisc_clockevent_init();
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notify_cpu_starting(cpu);
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/*
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* OK, now it's safe to let the boot CPU continue
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*/
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set_cpu_online(cpu, true);
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complete(&cpu_running);
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local_irq_enable();
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preempt_disable();
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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_startup_entry(CPUHP_AP_ONLINE_IDLE);
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}
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void handle_IPI(unsigned int ipi_msg)
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{
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unsigned int cpu = smp_processor_id();
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switch (ipi_msg) {
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case IPI_WAKEUP:
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break;
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case IPI_RESCHEDULE:
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scheduler_ipi();
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break;
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case IPI_CALL_FUNC:
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generic_smp_call_function_interrupt();
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break;
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case IPI_CALL_FUNC_SINGLE:
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generic_smp_call_function_single_interrupt();
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break;
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default:
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WARN(1, "CPU%u: Unknown IPI message 0x%x\n", cpu, ipi_msg);
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break;
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}
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}
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void smp_send_reschedule(int cpu)
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{
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smp_cross_call(cpumask_of(cpu), IPI_RESCHEDULE);
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}
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static void stop_this_cpu(void *dummy)
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{
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/* Remove this CPU */
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set_cpu_online(smp_processor_id(), false);
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local_irq_disable();
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/* CPU Doze */
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if (mfspr(SPR_UPR) & SPR_UPR_PMP)
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mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
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/* If that didn't work, infinite loop */
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while (1)
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;
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}
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void smp_send_stop(void)
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{
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smp_call_function(stop_this_cpu, NULL, 0);
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}
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/* not supported, yet */
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int setup_profiling_timer(unsigned int multiplier)
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{
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return -EINVAL;
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}
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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_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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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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/* TLB flush operations - Performed on each CPU*/
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static inline void ipi_flush_tlb_all(void *ignored)
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{
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local_flush_tlb_all();
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}
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void flush_tlb_all(void)
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{
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on_each_cpu(ipi_flush_tlb_all, NULL, 1);
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}
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/*
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* FIXME: implement proper functionality instead of flush_tlb_all.
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* *But*, as things currently stands, the local_tlb_flush_* functions will
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* all boil down to local_tlb_flush_all anyway.
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*/
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void flush_tlb_mm(struct mm_struct *mm)
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{
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on_each_cpu(ipi_flush_tlb_all, NULL, 1);
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}
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void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
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{
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on_each_cpu(ipi_flush_tlb_all, NULL, 1);
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}
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void flush_tlb_range(struct vm_area_struct *vma,
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unsigned long start, unsigned long end)
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{
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on_each_cpu(ipi_flush_tlb_all, NULL, 1);
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}
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