arch/arm/include/asm/mmu_context.h

   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 <linux/sched.h>
  18 #include <asm/cacheflush.h>
  19 #include <asm/cachetype.h>
  20 #include <asm/proc-fns.h>
  21 #include <asm-generic/mm_hooks.h>
  22
  23 void __check_kvm_seq(struct mm_struct *mm);
  24
  25 #ifdef CONFIG_CPU_HAS_ASID
  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 #define ASID_FIRST_VERSION      (1 << ASID_BITS)
  44
  45 extern unsigned int cpu_last_asid;
  46
  47 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
  48 void __new_context(struct mm_struct *mm);
  49
  50 static inline void check_context(struct mm_struct *mm)
  51 {
  52         if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
  53                 __new_context(mm);
  54
  55         if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
  56                 __check_kvm_seq(mm);
  57 }
  58
  59 #define init_new_context(tsk,mm)        (__init_new_context(tsk,mm),0)
  60
  61 #else
  62
  63 static inline void check_context(struct mm_struct *mm)
  64 {
  65 #ifdef CONFIG_MMU
  66         if (unlikely(mm->context.kvm_seq != init_mm.context.kvm_seq))
  67                 __check_kvm_seq(mm);
  68 #endif
  69 }
  70
  71 #define init_new_context(tsk,mm)        0
  72
  73 #endif
  74
  75 #define destroy_context(mm)             do { } while(0)
  76
  77 /*
  78  * This is called when "tsk" is about to enter lazy TLB mode.
  79  *
  80  * mm:  describes the currently active mm context
  81  * tsk: task which is entering lazy tlb
  82  * cpu: cpu number which is entering lazy tlb
  83  *
  84  * tsk->mm will be NULL
  85  */
  86 static inline void
  87 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  88 {
  89 }
  90
  91 /*
  92  * This is the actual mm switch as far as the scheduler
  93  * is concerned.  No registers are touched.  We avoid
  94  * calling the CPU specific function when the mm hasn't
  95  * actually changed.
  96  */
  97 static inline void
  98 switch_mm(struct mm_struct *prev, struct mm_struct *next,
  99           struct task_struct *tsk)
 100 {
 101 #ifdef CONFIG_MMU
 102         unsigned int cpu = smp_processor_id();
 103
 104 #ifdef CONFIG_SMP
 105         /* check for possible thread migration */
 106         if (!cpumask_empty(mm_cpumask(next)) &&
 107             !cpumask_test_cpu(cpu, mm_cpumask(next)))
 108                 __flush_icache_all();
 109 #endif
 110         if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
 111                 check_context(next);
 112                 cpu_switch_mm(next->pgd, next);
 113                 if (cache_is_vivt())
 114                         cpumask_clear_cpu(cpu, mm_cpumask(prev));
 115         }
 116 #endif
 117 }
 118
 119 #define deactivate_mm(tsk,mm)   do { } while (0)
 120 #define activate_mm(prev,next)  switch_mm(prev, next, NULL)
 121
 122 #endif