Kernel/vfs/mmap.c

   1 /*
   2  * Acess2 VFS
   3  * - Open, Close and ChDir
   4  */
   5 #define DEBUG   1
   6 #include <acess.h>
   7 #include <vfs.h>
   8 #include <vfs_ext.h>
   9 #include <vfs_int.h>
  10
  11 #define MMAP_PAGES_PER_BLOCK    16
  12
  13 // === STRUCTURES ===
  14 typedef struct sVFS_MMapPageBlock       tVFS_MMapPageBlock;
  15 struct sVFS_MMapPageBlock
  16 {
  17         tVFS_MMapPageBlock      *Next;
  18         Uint64  BaseOffset;     // Must be a multiple of MMAP_PAGES_PER_BLOCK*PAGE_SIZE
  19         tPAddr  PhysAddrs[MMAP_PAGES_PER_BLOCK];
  20 };
  21
  22 // === CODE ===
  23 void *VFS_MMap(void *DestHint, size_t Length, int Protection, int Flags, int FD, Uint64 Offset)
  24 {
  25         tVFS_Handle     *h;
  26         tVAddr  mapping_dest;
  27          int    npages, pagenum;
  28         tVFS_MMapPageBlock      *pb, *prev;
  29
  30         ENTER("pDestHint iLength xProtection xFlags xFD XOffset", DestHint, Length, Protection, Flags, FD, Offset);
  31
  32         npages = ((Offset & (PAGE_SIZE-1)) + Length + (PAGE_SIZE - 1)) / PAGE_SIZE;
  33         pagenum = Offset / PAGE_SIZE;
  34
  35         mapping_dest = (tVAddr)DestHint;
  36
  37         // TODO: Locate space for the allocation
  38
  39         // Handle anonymous mappings
  40         if( Flags & MMAP_MAP_ANONYMOUS )
  41         {
  42                 int i;
  43                 for( i = 0; i < npages; i ++ ) {
  44                         tPAddr rv = MM_Allocate(mapping_dest + i * PAGE_SIZE);
  45                         if( !rv ) {
  46                                 // TODO: Error
  47                         }
  48                 }
  49                 LEAVE_RET('p', (void*)mapping_dest);
  50         }
  51
  52         h = VFS_GetHandle(FD);
  53         if( !h || !h->Node )    LEAVE_RET('n', NULL);
  54
  55         LOG("h = %p", h);
  56
  57         // Search for existing mapping for each page
  58         // - Sorted list of 16 page blocks
  59         for(
  60                 pb = h->Node->MMapInfo, prev = NULL;
  61                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  62                 prev = pb, pb = pb->Next
  63                 );
  64
  65         // - Allocate a block if needed
  66         if( !pb || pb->BaseOffset > pagenum )
  67         {
  68                 void    *old_pb = pb;
  69                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  70                 if(!pb) LEAVE_RET('n', NULL);
  71                 pb->Next = old_pb;
  72                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
  73                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
  74                 if(prev)
  75                         prev->Next = pb;
  76                 else
  77                         h->Node->MMapInfo = pb;
  78         }
  79
  80         // - Map (and allocate) pages
  81         while( npages -- )
  82         {
  83                 if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
  84                 {
  85                         if( h->Node->MMap )
  86                                 h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
  87                         else
  88                         {
  89                                 // Allocate pages and read data
  90                                 if( MM_Allocate(mapping_dest) == 0 ) {
  91                                         // TODO: Unwrap
  92                                         return NULL;
  93                                 }
  94                                 h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
  95                         }
  96                         pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
  97 //                      MM_SetPageInfo( pb->PhysAddrs[pagenum - pb->BaseOffset], h->Node, pagenum*PAGE_SIZE );
  98                 }
  99                 else
 100                 {
 101                         MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 102                 }
 103                 pagenum ++;
 104                 mapping_dest += PAGE_SIZE;
 105
 106                 // Roll on to next block if needed
 107                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 108                 {
 109                         if( pb->Next && pb->Next->BaseOffset == pagenum )
 110                                 pb = pb->Next;
 111                         else
 112                         {
 113                                 tVFS_MMapPageBlock      *oldpb = pb;
 114                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
 115                                 pb->Next = oldpb->Next;
 116                                 pb->BaseOffset = pagenum;
 117                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 118                                 oldpb->Next = pb;
 119                         }
 120                         pagenum = 0;
 121                 }
 122         }
 123
 124         LEAVE('n');
 125         return NULL;
 126 }
 127
 128 int VFS_MUnmap(void *Addr, size_t Length)
 129 {
 130         return 0;
 131 }