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_vmalloc_seq(struct mm_struct *mm);
  24
  25 #ifdef CONFIG_CPU_HAS_ASID
  26
  27 void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk);
  28 #define init_new_context(tsk,mm)        ({ mm->context.id = 0; })
  29
  30 #else   /* !CONFIG_CPU_HAS_ASID */
  31
  32 #ifdef CONFIG_MMU
  33
  34 static inline void check_and_switch_context(struct mm_struct *mm,
  35                                             struct task_struct *tsk)
  36 {
  37         if (unlikely(mm->context.vmalloc_seq != init_mm.context.vmalloc_seq))
  38                 __check_vmalloc_seq(mm);
  39
  40         if (irqs_disabled())
  41                 /*
  42                  * cpu_switch_mm() needs to flush the VIVT caches. To avoid
  43                  * high interrupt latencies, defer the call and continue
  44                  * running with the old mm. Since we only support UP systems
  45                  * on non-ASID CPUs, the old mm will remain valid until the
  46                  * finish_arch_post_lock_switch() call.
  47                  */
  48                 set_ti_thread_flag(task_thread_info(tsk), TIF_SWITCH_MM);
  49         else
  50                 cpu_switch_mm(mm->pgd, mm);
  51 }
  52
  53 #define finish_arch_post_lock_switch \
  54         finish_arch_post_lock_switch
  55 static inline void finish_arch_post_lock_switch(void)
  56 {
  57         if (test_and_clear_thread_flag(TIF_SWITCH_MM)) {
  58                 struct mm_struct *mm = current->mm;
  59                 cpu_switch_mm(mm->pgd, mm);
  60         }
  61 }
  62
  63 #endif  /* CONFIG_MMU */
  64
  65 #define init_new_context(tsk,mm)        0
  66
  67 #endif  /* CONFIG_CPU_HAS_ASID */
  68
  69 #define destroy_context(mm)             do { } while(0)
  70 #define activate_mm(prev,next)          switch_mm(prev, next, NULL)
  71
  72 /*
  73  * This is called when "tsk" is about to enter lazy TLB mode.
  74  *
  75  * mm:  describes the currently active mm context
  76  * tsk: task which is entering lazy tlb
  77  * cpu: cpu number which is entering lazy tlb
  78  *
  79  * tsk->mm will be NULL
  80  */
  81 static inline void
  82 enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
  83 {
  84 }
  85
  86 /*
  87  * This is the actual mm switch as far as the scheduler
  88  * is concerned.  No registers are touched.  We avoid
  89  * calling the CPU specific function when the mm hasn't
  90  * actually changed.
  91  */
  92 static inline void
  93 switch_mm(struct mm_struct *prev, struct mm_struct *next,
  94           struct task_struct *tsk)
  95 {
  96 #ifdef CONFIG_MMU
  97         unsigned int cpu = smp_processor_id();
  98
  99 #ifdef CONFIG_SMP
 100         /* check for possible thread migration */
 101         if (!cpumask_empty(mm_cpumask(next)) &&
 102             !cpumask_test_cpu(cpu, mm_cpumask(next)))
 103                 __flush_icache_all();
 104 #endif
 105         if (!cpumask_test_and_set_cpu(cpu, mm_cpumask(next)) || prev != next) {
 106                 check_and_switch_context(next, tsk);
 107                 if (cache_is_vivt())
 108                         cpumask_clear_cpu(cpu, mm_cpumask(prev));
 109         }
 110 #endif
 111 }
 112
 113 #define deactivate_mm(tsk,mm)   do { } while (0)
 114
 115 #endif