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, mapping_base;
  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_base = (tVAddr)DestHint;
  36         mapping_dest = mapping_base & ~(PAGE_SIZE-1);
  37
  38         // TODO: Locate space for the allocation
  39
  40         // Handle anonymous mappings
  41         if( Flags & MMAP_MAP_ANONYMOUS )
  42         {
  43                 for( ; npages --; mapping_dest += PAGE_SIZE )
  44                 {
  45                         if( MM_GetPhysAddr(mapping_dest) ) {
  46                                 // TODO: Set flags to COW if needed (well, if shared)
  47                         }
  48                         else {
  49                                 if( !MM_Allocate(mapping_dest) ) {
  50                                         // TODO: Error
  51                                         Log_Warning("VFS", "VFS_MMap: Anon alloc to %p failed", mapping_dest);
  52                                 }
  53                                 LOG("Anon map to %p", mapping_dest);
  54                         }
  55                 }
  56                 LEAVE_RET('p', (void*)mapping_base);
  57         }
  58
  59         h = VFS_GetHandle(FD);
  60         if( !h || !h->Node )    LEAVE_RET('n', NULL);
  61
  62         LOG("h = %p", h);
  63
  64         Mutex_Acquire( &h->Node->Lock );
  65
  66         // Search for existing mapping for each page
  67         // - Sorted list of 16 page blocks
  68         for(
  69                 pb = h->Node->MMapInfo, prev = NULL;
  70                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  71                 prev = pb, pb = pb->Next
  72                 );
  73
  74         LOG("pb = %p, pb->BaseOffset = %X", pb, pb ? pb->BaseOffset : 0);
  75
  76         // - Allocate a block if needed
  77         if( !pb || pb->BaseOffset > pagenum )
  78         {
  79                 void    *old_pb = pb;
  80                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  81                 if(!pb) {
  82                         Mutex_Release( &h->Node->Lock );
  83                         LEAVE_RET('n', NULL);
  84                 }
  85                 pb->Next = old_pb;
  86                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
  87                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
  88                 if(prev)
  89                         prev->Next = pb;
  90                 else
  91                         h->Node->MMapInfo = pb;
  92         }
  93
  94         // - Map (and allocate) pages
  95         while( npages -- )
  96         {
  97                 if( MM_GetPhysAddr(mapping_dest) == 0 )
  98                 {
  99                         if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
 100                         {
 101                                 if( h->Node->MMap )
 102                                         h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
 103                                 else
 104                                 {
 105                                         // Allocate pages and read data
 106                                         if( MM_Allocate(mapping_dest) == 0 ) {
 107                                                 // TODO: Unwrap
 108                                                 Mutex_Release( &h->Node->Lock );
 109                                                 LEAVE('n');
 110                                                 return NULL;
 111                                         }
 112                                         h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
 113                                 }
 114                                 pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
 115                                 MM_SetPageNode( pb->PhysAddrs[pagenum - pb->BaseOffset], h->Node );
 116                                 LOG("Read and map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 117                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 118                         }
 119                         else
 120                         {
 121                                 MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 122                                 LOG("Cached map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 123                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 124                         }
 125                         h->Node->ReferenceCount ++;
 126
 127                         // Set flags
 128                         if( !(Protection & MMAP_PROT_WRITE) ) {
 129                                 MM_SetFlags(mapping_dest, MM_PFLAG_RO, MM_PFLAG_RO);
 130                         }
 131                         else {
 132                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 133                         }
 134                 }
 135                 else
 136                 {
 137                         LOG("Flag update on %p", mapping_dest);
 138                         if( (MM_GetFlags(mapping_dest) & MM_PFLAG_RO) && (Protection & MMAP_PROT_WRITE) )
 139                         {
 140                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 141                         }
 142                 }
 143                 if( Flags & MMAP_MAP_PRIVATE )
 144                         MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
 145                 pagenum ++;
 146                 mapping_dest += PAGE_SIZE;
 147
 148                 // Roll on to next block if needed
 149                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 150                 {
 151                         if( pb->Next && pb->Next->BaseOffset == pagenum )
 152                                 pb = pb->Next;
 153                         else
 154                         {
 155                                 tVFS_MMapPageBlock      *oldpb = pb;
 156                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
 157                                 pb->Next = oldpb->Next;
 158                                 pb->BaseOffset = pagenum;
 159                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 160                                 oldpb->Next = pb;
 161                         }
 162                         pagenum = 0;
 163                 }
 164         }
 165
 166         Mutex_Release( &h->Node->Lock );
 167
 168         LEAVE('p', mapping_base);
 169         return (void*)mapping_base;
 170 }
 171
 172 int VFS_MUnmap(void *Addr, size_t Length)
 173 {
 174         return 0;
 175 }