LXR linux/arch/arm/include/asm/mmu

   1/*
   2 *  arch/arm/include/asm/mmu_context.h
   3 *
   4 *  Copyright (C) 1996 Russell King.
   5 *
   6 * This program is free software; you can redistribute it and/or modify
   7 * it under the terms of the GNU General Public License version 2 as
   8 * published by the Free Software Foundation.
   9 *
  10 *  Changelog:
  11 *   27-06-1996 RMK     Created
  12 */
  13#ifndef __ASM_ARM_MMU_CONTEXT_H
  14#define __ASM_ARM_MMU_CONTEXT_H
  15
  16#include <linux/compiler.h>
  17#include <asm/cacheflush.h>
  18#include <asm/cachetype.h>
  19#include <asm/proc-fns.h>
  20#include <asm-generic/mm_hooks.h>
  21
  22void __check_kvm_seq(struct mm_struct *mm);
  23
  24#ifdef CONFIG_CPU_HAS_ASID
  25
  26/*
  27 * On ARMv6, we have the following structure in the Context ID:
  28 *
  29 * 31                         7          0
  30 * +-------------------------+-----------+
  31 * |      process ID         |   ASID    |
  32 * +-------------------------+-----------+
  33 * |              context ID             |
  34 * +-------------------------------------+
  35 *
  36 * The ASID is used to tag entries in the CPU caches and TLBs.
  37 * The context ID is used by debuggers and trace logic, and
  38 * should be unique within all running processes.
  39 */
  40#define ASID_BITS               8
  41#define ASID_MASK               ((~0) << ASID_BITS)
  42#define ASID_FIRST_VERSION      (1 << ASID_BITS)
  43
  44extern unsigned int cpu_last_asid;
  45
  46void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
  47void __new_context(struct mm_struct *mm);
  48
  49static inline void check_context(struct mm_struct *mm)
  50{
  51        if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
  52                __new_context(mm);
  53
  54        if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
  55                __check_kvm_seq(mm);
  56}
  57
  58#define init_new_context(tsk,mm)        (__init_new_context(tsk,mm),0)
  59
  60#else
  61
  62static inline void check_context(struct mm_struct *mm)
  63{
  64        if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
  65                __check_kvm_seq(mm);
  66}
  67
  68#define init_new_context(tsk,mm)        0
  69
  70#endif
  71
  72#define destroy_context(mm)             do { } while(0)
  73
  74/*
  75 * This is called when "tsk" is about to enter lazy TLB mode.
  76 *
  77 * mm:  describes the currently active mm context
  78 * tsk: task which is entering lazy tlb
  79 * cpu: cpu number which is entering lazy tlb
  80 *
  81 * tsk->mm will be NULL
  82 */
  83static inline void
  84enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  85{
  86}
  87
  88/*
  89 * This is the actual mm switch as far as the scheduler
  90 * is concerned.  No registers are touched.  We avoid
  91 * calling the CPU specific function when the mm hasn't
  92 * actually changed.
  93 */
  94static inline void
  95switch_mm(struct mm_struct *prev, struct mm_struct *next,
  96          struct task_struct *tsk)
  97{
  98#ifdef CONFIG_MMU
  99        unsigned int cpu = smp_processor_id();
 100
 101#ifdef CONFIG_SMP
 102        /* check for possible thread migration */
 103        if (!cpus_empty(next->cpu_vm_mask) && !cpu_isset(cpu, next->cpu_vm_mask))
 104                __flush_icache_all();
 105#endif
 106        if (!cpu_test_and_set(cpu, next->cpu_vm_mask) || prev != next) {
 107                check_context(next);
 108                cpu_switch_mm(next->pgd, next);
 109                if (cache_is_vivt())
 110                        cpu_clear(cpu, prev->cpu_vm_mask);
 111        }
 112#endif
 113}
 114
 115#define deactivate_mm(tsk,mm)   do { } while (0)
 116#define activate_mm(prev,next)  switch_mm(prev, next, NULL)
 117
 118#endif
 119