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