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/*
* arch/arm/include/asm/mmu_context.h
*
* Copyright (C) 1996 Russell King.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Changelog:
* 27-06-1996 RMK Created
*/
#ifndef __ASM_ARM_MMU_CONTEXT_H
#define __ASM_ARM_MMU_CONTEXT_H
#include <linux/compiler.h>
#include <linux/sched.h>
#include <asm/cacheflush.h>
#include <asm/cachetype.h>
#include <asm/proc-fns.h>
#include <asm-generic/mm_hooks.h>
void __check_kvm_seq(struct mm_struct *mm);
#ifdef CONFIG_CPU_HAS_ASID
/*
* On ARMv6, we have the following structure in the Context ID:
*
* 31 7 0
* +-------------------------+-----------+
* | process ID | ASID |
* +-------------------------+-----------+
* | context ID |
* +-------------------------------------+
*
* The ASID is used to tag entries in the CPU caches and TLBs.
* The context ID is used by debuggers and trace logic, and
* should be unique within all running processes.
*/
#define ASID_BITS 8
#define ASID_MASK ((~0) << ASID_BITS)
#define ASID_FIRST_VERSION (1 << ASID_BITS)
extern unsigned int cpu_last_asid;
#ifdef CONFIG_SMP
DECLARE_PER_CPU(struct mm_struct *, current_mm);
#endif
void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
void __new_context(struct mm_struct *mm);
static inline void check_context(struct mm_struct *mm)
{
/*
* This code is executed with interrupts enabled. Therefore,
* mm->context.id cannot be updated to the latest ASID version
* on a different CPU (and condition below not triggered)
* without first getting an IPI to reset the context. The
* alternative is to take a read_lock on mm->context.id_lock
* (after changing its type to rwlock_t).
*/
if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
__new_context(mm);
if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
__check_kvm_seq(mm);
}
#define init_new_context(tsk,mm) (__init_new_context(tsk,mm),0)
#else
static inline void check_context(struct mm_struct *mm)
{
#ifdef CONFIG_MMU
if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
__check_kvm_seq(mm);
#endif
}
#define init_new_context(tsk,mm) 0
#endif
#define destroy_context(mm) do { } while(0)
/*
* This is called when "tsk" is about to enter lazy TLB mode.
*
* mm: describes the currently active mm context
* tsk: task which is entering lazy tlb
* cpu: cpu number which is entering lazy tlb
*
* tsk->mm will be NULL
*/
static inline void
enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
{
}
/*
* This is the actual mm switch as far as the scheduler
* is concerned. No registers are touched. We avoid
* calling the CPU specific function when the mm hasn't
* actually changed.
*/
static inline void
switch_mm(struct mm_struct *prev, struct mm_struct *next,
struct task_struct *tsk)
{
#ifdef CONFIG_MMU
unsigned int cpu = smp_processor_id();
#ifdef CONFIG_SMP
/* check for possible thread migration */
if (!cpumask_empty(mm_cpumask(next)) &&
!cpumask_test_cpu(cpu, mm_cpumask(next)))
__flush_icache_all();
#endif
if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
#ifdef CONFIG_SMP
struct mm_struct **crt_mm = &per_cpu(current_mm, cpu);
*crt_mm = next;
#endif
check_context(next);
cpu_switch_mm(next->pgd, next);
if (cache_is_vivt())
cpumask_clear_cpu(cpu, mm_cpumask(prev));
}
#endif
}
#define deactivate_mm(tsk,mm) do { } while (0)
#define activate_mm(prev,next) switch_mm(prev, next, NULL)
#endif
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