Kernel/arch/arm7/mm_virt.c

   1 /*
   2  * Acess2
   3  *
   4  * ARM7 Virtual Memory Manager
   5  * - arch/arm7/mm_virt.c
   6  */
   7 #include <mm_virt.h>
   8
   9 // === TYPES ===
  10 typedef struct
  11 {
  12         tPAddr  PhysAddr;
  13         Uint8   Size;
  14         Uint8   Domain;
  15 } tMM_PageInfo;
  16
  17 // === GLOBALS ===
  18 Uint32  *gMM_KernelTable0 = (void*)MM_TABLE0KERN;
  19 Uint32  *gMM_KernelTable1 = (void*)MM_TABLE1KERN;
  20
  21 // === CODE ===
  22 int MM_InitialiseVirtual(void)
  23 {
  24 }
  25
  26 int MM_int_GetPageInfo(tVAddr VAddr, tMM_PageInfo *pi)
  27 {
  28         Uint32  *table0, table1;
  29         Uint32  desc;
  30
  31         if(VAddr & 0x80000000 ) {
  32                 table0 = MM_TABLE0KERN;
  33                 table1 = MM_TABLE1KERN;
  34         }
  35         else {
  36                 table0 = MM_TABLE0USER;
  37                 table1 = MM_TABLE1USER;
  38         }
  39         VAddr & 0x7FFFFFFF;
  40
  41         desc = table0[ VAddr >> 20 ];
  42
  43         switch( (desc & 3) )
  44         {
  45         // 0: Unmapped
  46         case 0:
  47                 pi->PhysAddr = 0;
  48                 pi->Size = 20;
  49                 pi->Domain = 0;
  50                 return 1;
  51
  52         // 1: Coarse page table
  53         case 1:
  54                 // Domain from top level table
  55                 pi->Domain = (desc >> 5) & 7;
  56                 // Get next level
  57                 desc = table1[ VAddr >> 12 ];
  58                 switch( desc & 3 )
  59                 {
  60                 // 0: Unmapped
  61                 case 0:
  62                         pi->Size = 12;
  63                         return 1;
  64                 // 1: Large Page (64KiB)
  65                 case 1:
  66                         pi->Size = 16;
  67                         pi->PhysAddr = desc & 0xFFFF0000;
  68                         return 0;
  69                 // 2/3: Small page
  70                 case 2:
  71                 case 3:
  72                         pi->Size = 12;
  73                         pi->PhysAddr = desc & 0xFFFFF000;
  74                         pi->bExecutable = desc & 1;
  75                         pi->bGlobal = !(desc >> 11);
  76                         pi->bSharec = (desc >> 10) & 1;
  77                         return 1;
  78                 }
  79                 return 1;
  80
  81         // 2: Section (or Supersection)
  82         case 2:
  83                 if( desc & (1 << 18) ) {
  84                         // Supersection
  85                         pi->PhysAddr = desc & 0xFF000000;
  86                         pi->PhysAddr |= ((desc >> 20) & 0xF) << 32;
  87                         pi->PhysAddr |= ((desc >> 5) & 0x7) << 36;
  88                         pi->Size = 24;
  89                         pi->Domain = 0; // Superpages default to zero
  90                         return 0;
  91                 }
  92
  93                 // Section
  94                 pi->PhysAddr = desc & 0xFFF80000;
  95                 pi->Size = 20;
  96                 pi->Domain = (desc >> 5) & 7;
  97                 return 0;
  98
  99         // 3: Reserved (invalid)
 100         case 3:
 101                 pi->PhysAddr = 0;
 102                 pi->Size = 20;
 103                 pi->Domain = 0;
 104                 return 2;
 105         }
 106 }
 107
 108 // --- Exports ---
 109 tPAddr MM_GetPhysAddr(tVAddr VAddr)
 110 {
 111         tMM_PageInfo    pi;
 112         if( MM_int_GetPageInfo(VAddr, &pi) )
 113                 return 0;
 114         return pi.PhysAddr;
 115 }