forked from Minki/linux
b5466f8728
ASIDs are allocated to MMU contexts based on a rolling counter. This means that after 255 allocations we must invalidate all existing ASIDs via an expensive IPI mechanism to synchronise all of the online CPUs and ensure that all tasks execute with an ASID from the new generation. This patch changes the rollover behaviour so that we rely instead on the hardware broadcasting of the TLB invalidation to avoid the IPI calls. This works by keeping track of the active ASID on each core, which is then reserved in the case of a rollover so that currently scheduled tasks can continue to run. For cores without hardware TLB broadcasting, we keep track of pending flushes in a cpumask, so cores can flush their local TLB before scheduling a new mm. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Tested-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
/*
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* arch/arm/include/asm/mmu_context.h
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*
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* Copyright (C) 1996 Russell King.
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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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* Changelog:
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* 27-06-1996 RMK Created
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*/
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#ifndef __ASM_ARM_MMU_CONTEXT_H
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#define __ASM_ARM_MMU_CONTEXT_H
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#include <linux/compiler.h>
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#include <linux/sched.h>
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#include <asm/cacheflush.h>
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#include <asm/cachetype.h>
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#include <asm/proc-fns.h>
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#include <asm-generic/mm_hooks.h>
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void __check_kvm_seq(struct mm_struct *mm);
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#ifdef CONFIG_CPU_HAS_ASID
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void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk);
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#define init_new_context(tsk,mm) ({ mm->context.id = 0; })
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#else /* !CONFIG_CPU_HAS_ASID */
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#ifdef CONFIG_MMU
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static inline void check_and_switch_context(struct mm_struct *mm,
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struct task_struct *tsk)
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{
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if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
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__check_kvm_seq(mm);
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if (irqs_disabled())
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/*
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* cpu_switch_mm() needs to flush the VIVT caches. To avoid
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* high interrupt latencies, defer the call and continue
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* running with the old mm. Since we only support UP systems
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* on non-ASID CPUs, the old mm will remain valid until the
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* finish_arch_post_lock_switch() call.
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*/
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set_ti_thread_flag(task_thread_info(tsk), TIF_SWITCH_MM);
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else
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cpu_switch_mm(mm->pgd, mm);
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}
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#define finish_arch_post_lock_switch \
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finish_arch_post_lock_switch
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static inline void finish_arch_post_lock_switch(void)
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{
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if (test_and_clear_thread_flag(TIF_SWITCH_MM)) {
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struct mm_struct *mm = current->mm;
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cpu_switch_mm(mm->pgd, mm);
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}
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}
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#endif /* CONFIG_MMU */
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#define init_new_context(tsk,mm) 0
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#endif /* CONFIG_CPU_HAS_ASID */
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#define destroy_context(mm) do { } while(0)
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#define activate_mm(prev,next) switch_mm(prev, next, NULL)
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/*
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* This is called when "tsk" is about to enter lazy TLB mode.
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*
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* mm: describes the currently active mm context
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* tsk: task which is entering lazy tlb
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* cpu: cpu number which is entering lazy tlb
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*
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* tsk->mm will be NULL
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*/
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static inline void
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enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
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{
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}
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/*
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* This is the actual mm switch as far as the scheduler
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* is concerned. No registers are touched. We avoid
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* calling the CPU specific function when the mm hasn't
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* actually changed.
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*/
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static inline void
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switch_mm(struct mm_struct *prev, struct mm_struct *next,
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struct task_struct *tsk)
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{
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#ifdef CONFIG_MMU
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unsigned int cpu = smp_processor_id();
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#ifdef CONFIG_SMP
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/* check for possible thread migration */
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if (!cpumask_empty(mm_cpumask(next)) &&
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!cpumask_test_cpu(cpu, mm_cpumask(next)))
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__flush_icache_all();
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#endif
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if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
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check_and_switch_context(next, tsk);
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if (cache_is_vivt())
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cpumask_clear_cpu(cpu, mm_cpumask(prev));
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}
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#endif
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}
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#define deactivate_mm(tsk,mm) do { } while (0)
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#endif
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