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