include/asm-sh/mmu_context.h

   1 /*
   2  * Copyright (C) 1999 Niibe Yutaka
   3  *
   4  * ASID handling idea taken from MIPS implementation.
   5  */
   6 #ifndef __ASM_SH_MMU_CONTEXT_H
   7 #define __ASM_SH_MMU_CONTEXT_H
   8
   9 /* The MMU "context" consists of two things:
  10      (a) TLB cache version (or round, cycle whatever expression you like)
  11      (b) ASID (Address Space IDentifier)
  12  */
  13
  14 /*
  15  * Cache of MMU context last used.
  16  */
  17 extern unsigned long mmu_context_cache;
  18
  19 #define MMU_CONTEXT_ASID_MASK 0xff
  20 #define MMU_CONTEXT_VERSION_MASK 0xffffff00
  21 #define MMU_CONTEXT_FIRST_VERSION 0x100
  22 #define NO_CONTEXT 0
  23
  24 extern __inline__ void
  25 get_new_mmu_context(struct mm_struct *mm)
  26 {
  27         unsigned long mc = ++mmu_context_cache;
  28
  29         if (!(mc & MMU_CONTEXT_ASID_MASK)) {
  30                 /* We exhaust ASID of this version.
  31                    Flush all TLB and start new cycle. */
  32                 flush_tlb_all();
  33                 /* Fix version if needed.
  34                    Note that we avoid version #0 to distingush NO_CONTEXT. */
  35                 if (!mc)
  36                         mmu_context_cache = mc = MMU_CONTEXT_FIRST_VERSION;
  37         }
  38         mm->context = mc;
  39 }
  40
  41 /*P
  42  * Get MMU context if needed.
  43  */
  44 extern __inline__ void
  45 get_mmu_context(struct mm_struct *mm)
  46 {
  47         if (mm) {
  48                 unsigned long mc = mmu_context_cache;
  49                 /* Check if we have old version of context.
  50                    If it's old, we need to get new context with new version. */
  51                 if ((mm->context ^ mc) & MMU_CONTEXT_VERSION_MASK)
  52                         get_new_mmu_context(mm);
  53         }
  54 }
  55
  56 /*P
  57  * Initialize the context related info for a new mm_struct
  58  * instance.
  59  */
  60 extern __inline__ void init_new_context(struct task_struct *tsk,
  61                                         struct mm_struct *mm)
  62 {
  63         mm->context = NO_CONTEXT;
  64 }
  65
  66 /*P
  67  * Destroy context related info for an mm_struct that is about
  68  * to be put to rest.
  69  */
  70 extern __inline__ void destroy_context(struct mm_struct *mm)
  71 {
  72         mm->context = NO_CONTEXT;
  73 }
  74
  75 /* Other MMU related constants. */
  76
  77 #define MMU_PTEH        0xFFFFFFF0      /* Page table entry register HIGH */
  78 #define MMU_PTEL        0xFFFFFFF4      /* Page table entry register LOW */
  79 #define MMUCR           0xFFFFFFE0      /* MMU Control Register */
  80
  81 #define MMU_TLB_ADDRESS_ARRAY 0xF2000000
  82 #define MMU_PAGE_ASSOC_BIT 0x80
  83
  84 #define MMU_NTLB_ENTRIES       128      /* for 7708 */
  85
  86 #define MMU_CONTROL_INIT 0x007  /* SV=0, TF=1, IX=1, AT=1 */
  87
  88 #include <asm/uaccess.h> /* to get the definition of  __m */
  89
  90 extern __inline__ void set_asid (unsigned long asid)
  91 {
  92         __asm__ __volatile__ ("mov.l    %0,%1"
  93                               : /* no output */
  94                               : "r" (asid), "m" (__m(MMU_PTEH)));
  95 }
  96
  97 extern __inline__ unsigned long get_asid (void)
  98 {
  99         unsigned long asid;
 100
 101         __asm__ __volatile__ ("mov.l %1,%0"
 102                               : "=r" (asid)
 103                               : "m" (__m(MMU_PTEH)));
 104         asid &= MMU_CONTEXT_ASID_MASK;
 105         return asid;
 106 }
 107
 108 /*P
 109  * After we have set current->mm to a new value, this activates
 110  * the context for the new mm so we see the new mappings.
 111  */
 112 extern __inline__ void activate_context(struct mm_struct *mm)
 113 {
 114         get_mmu_context(mm);
 115         set_asid(mm->context & MMU_CONTEXT_ASID_MASK);
 116 }
 117
 118 /* MMU_TTB can be used for optimizing the fault handling.
 119    (Currently not used) */
 120 #define MMU_TTB   0xFFFFFFF8    /* Translation table base register */
 121 extern __inline__ void switch_mm(struct mm_struct *prev,
 122                                  struct mm_struct *next,
 123                                  struct task_struct *tsk, unsigned int cpu)
 124 {
 125         if (prev != next) {
 126                 unsigned long __pgdir = __pa(next->pgd);
 127
 128                 __asm__ __volatile__("mov.l     %0,%1": \
 129                                      :"r" (__pgdir), "m" (__m(MMU_TTB)));
 130                 activate_context(next);
 131                 clear_bit(cpu, &prev->cpu_vm_mask);
 132         }
 133         set_bit(cpu, &next->cpu_vm_mask);
 134 }
 135
 136 #define activate_mm(prev, next) \
 137         switch_mm((prev),(next),NULL,smp_processor_id())
 138
 139 #endif /* __ASM_SH_MMU_CONTEXT_H */