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 #ifndef CONFIG_MMU
  17 #include "nommu_context.h"
  18 #else /* !CONFIG_MMU */
  19 #include <linux/compiler.h>
  20 #include <asm/cacheflush.h>
  21 #include <asm/proc-fns.h>
  22
  23 void __check_kvm_seq(struct mm_struct *mm);
  24
  25 #if __LINUX_ARM_ARCH__ >= 6
  26
  27 /*
  28  * On ARMv6, we have the following structure in the Context ID:
  29  *
  30  * 31                         7          0
  31  * +-------------------------+-----------+
  32  * |      process ID         |   ASID    |
  33  * +-------------------------+-----------+
  34  * |              context ID             |
  35  * +-------------------------------------+
  36  *
  37  * The ASID is used to tag entries in the CPU caches and TLBs.
  38  * The context ID is used by debuggers and trace logic, and
  39  * should be unique within all running processes.
  40  */
  41 #define ASID_BITS       8
  42 #define ASID_MASK       ((~0) << ASID_BITS)
  43
  44 extern unsigned int cpu_last_asid;
  45
  46 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
  47 void __new_context(struct mm_struct *mm);
  48
  49 static 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
  62 static 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  */
  83 static inline void
  84 enter_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  */
  94 static inline void
  95 switch_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         if (prev != next) {
 102                 cpu_set(cpu, next->cpu_vm_mask);
 103                 check_context(next);
 104                 cpu_switch_mm(next->pgd, next);
 105                 if (cache_is_vivt())
 106                         cpu_clear(cpu, prev->cpu_vm_mask);
 107         }
 108 #endif
 109 }
 110
 111 #define deactivate_mm(tsk,mm)   do { } while (0)
 112 #define activate_mm(prev,next)  switch_mm(prev, next, NULL)
 113
 114 #endif /* CONFIG_MMU */
 115 #endif