include/asm-arm/mmu_context.h

   1 /*
   2  *  linux/include/asm-arm/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/proc-fns.h>
  19
  20 void __check_kvm_seq(struct mm_struct *mm);
  21
  22 #if __LINUX_ARM_ARCH__ >= 6
  23
  24 /*
  25  * On ARMv6, we have the following structure in the Context ID:
  26  *
  27  * 31                         7          0
  28  * +-------------------------+-----------+
  29  * |      process ID         |   ASID    |
  30  * +-------------------------+-----------+
  31  * |              context ID             |
  32  * +-------------------------------------+
  33  *
  34  * The ASID is used to tag entries in the CPU caches and TLBs.
  35  * The context ID is used by debuggers and trace logic, and
  36  * should be unique within all running processes.
  37  */
  38 #define ASID_BITS       8
  39 #define ASID_MASK       ((~0) << ASID_BITS)
  40
  41 extern unsigned int cpu_last_asid;
  42
  43 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
  44 void __new_context(struct mm_struct *mm);
  45
  46 static inline void check_context(struct mm_struct *mm)
  47 {
  48         if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
  49                 __new_context(mm);
  50
  51         if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
  52                 __check_kvm_seq(mm);
  53 }
  54
  55 #define init_new_context(tsk,mm)        (__init_new_context(tsk,mm),0)
  56
  57 #else
  58
  59 static inline void check_context(struct mm_struct *mm)
  60 {
  61         if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
  62                 __check_kvm_seq(mm);
  63 }
  64
  65 #define init_new_context(tsk,mm)        0
  66
  67 #endif
  68
  69 #define destroy_context(mm)             do { } while(0)
  70
  71 /*
  72  * This is called when "tsk" is about to enter lazy TLB mode.
  73  *
  74  * mm:  describes the currently active mm context
  75  * tsk: task which is entering lazy tlb
  76  * cpu: cpu number which is entering lazy tlb
  77  *
  78  * tsk->mm will be NULL
  79  */
  80 static inline void
  81 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  82 {
  83 }
  84
  85 /*
  86  * This is the actual mm switch as far as the scheduler
  87  * is concerned.  No registers are touched.  We avoid
  88  * calling the CPU specific function when the mm hasn't
  89  * actually changed.
  90  */
  91 static inline void
  92 switch_mm(struct mm_struct *prev, struct mm_struct *next,
  93           struct task_struct *tsk)
  94 {
  95 #ifdef CONFIG_MMU
  96         unsigned int cpu = smp_processor_id();
  97
  98         if (prev != next) {
  99                 cpu_set(cpu, next->cpu_vm_mask);
 100                 check_context(next);
 101                 cpu_switch_mm(next->pgd, next);
 102                 if (cache_is_vivt())
 103                         cpu_clear(cpu, prev->cpu_vm_mask);
 104         }
 105 #endif
 106 }
 107
 108 #define deactivate_mm(tsk,mm)   do { } while (0)
 109 #define activate_mm(prev,next)  switch_mm(prev, next, NULL)
 110
 111 #endif