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 <asm/cacheflush.h>
  17 #include <asm/proc-fns.h>
  18
  19 #if __LINUX_ARM_ARCH__ >= 6
  20
  21 /*
  22  * On ARMv6, we have the following structure in the Context ID:
  23  *
  24  * 31                         7          0
  25  * +-------------------------+-----------+
  26  * |      process ID         |   ASID    |
  27  * +-------------------------+-----------+
  28  * |              context ID             |
  29  * +-------------------------------------+
  30  *
  31  * The ASID is used to tag entries in the CPU caches and TLBs.
  32  * The context ID is used by debuggers and trace logic, and
  33  * should be unique within all running processes.
  34  */
  35 #define ASID_BITS       8
  36 #define ASID_MASK       ((~0) << ASID_BITS)
  37
  38 extern unsigned int cpu_last_asid;
  39
  40 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm);
  41 void __new_context(struct mm_struct *mm);
  42
  43 static inline void check_context(struct mm_struct *mm)
  44 {
  45         if (unlikely((mm->context.id ^ cpu_last_asid) >> ASID_BITS))
  46                 __new_context(mm);
  47 }
  48
  49 #define init_new_context(tsk,mm)        (__init_new_context(tsk,mm),0)
  50
  51 #else
  52
  53 #define check_context(mm)               do { } while (0)
  54 #define init_new_context(tsk,mm)        0
  55
  56 #endif
  57
  58 #define destroy_context(mm)             do { } while(0)
  59
  60 /*
  61  * This is called when "tsk" is about to enter lazy TLB mode.
  62  *
  63  * mm:  describes the currently active mm context
  64  * tsk: task which is entering lazy tlb
  65  * cpu: cpu number which is entering lazy tlb
  66  *
  67  * tsk->mm will be NULL
  68  */
  69 static inline void
  70 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  71 {
  72 }
  73
  74 /*
  75  * This is the actual mm switch as far as the scheduler
  76  * is concerned.  No registers are touched.  We avoid
  77  * calling the CPU specific function when the mm hasn't
  78  * actually changed.
  79  */
  80 static inline void
  81 switch_mm(struct mm_struct *prev, struct mm_struct *next,
  82           struct task_struct *tsk)
  83 {
  84         unsigned int cpu = smp_processor_id();
  85
  86         if (prev != next) {
  87                 cpu_set(cpu, next->cpu_vm_mask);
  88                 check_context(next);
  89                 cpu_switch_mm(next->pgd, next);
  90                 if (cache_is_vivt())
  91                         cpu_clear(cpu, prev->cpu_vm_mask);
  92         }
  93 }
  94
  95 #define deactivate_mm(tsk,mm)   do { } while (0)
  96 #define activate_mm(prev,next)  switch_mm(prev, next, NULL)
  97
  98 #endif