Kernel/vfs/mmap.c

   1 /*
   2  * Acess2 VFS
   3  * - Open, Close and ChDir
   4  */
   5 #define DEBUG   0
   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                 size_t  ofs = 0;
  44                 for( ; npages --; mapping_dest += PAGE_SIZE, ofs += PAGE_SIZE )
  45                 {
  46                         if( MM_GetPhysAddr(mapping_dest) ) {
  47                                 // TODO: Set flags to COW if needed (well, if shared)
  48                                 MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
  49                                 memset( (void*)(mapping_base + ofs), 0, PAGE_SIZE - (mapping_base & (PAGE_SIZE-1)));
  50                         }
  51                         else {
  52                                 // TODO: Map a COW zero page instead
  53                                 if( !MM_Allocate(mapping_dest) ) {
  54                                         // TODO: Error
  55                                         Log_Warning("VFS", "VFS_MMap: Anon alloc to %p failed", mapping_dest);
  56                                 }
  57                                 memset((void*)mapping_dest, 0, PAGE_SIZE);
  58                                 LOG("Anon map to %p", mapping_dest);
  59                         }
  60                 }
  61                 LEAVE_RET('p', (void*)mapping_base);
  62         }
  63
  64         h = VFS_GetHandle(FD);
  65         if( !h || !h->Node )    LEAVE_RET('n', NULL);
  66
  67         LOG("h = %p", h);
  68
  69         Mutex_Acquire( &h->Node->Lock );
  70
  71         // Search for existing mapping for each page
  72         // - Sorted list of 16 page blocks
  73         for(
  74                 pb = h->Node->MMapInfo, prev = NULL;
  75                 pb && pb->BaseOffset + MMAP_PAGES_PER_BLOCK < pagenum;
  76                 prev = pb, pb = pb->Next
  77                 );
  78
  79         LOG("pb = %p, pb->BaseOffset = %X", pb, pb ? pb->BaseOffset : 0);
  80
  81         // - Allocate a block if needed
  82         if( !pb || pb->BaseOffset > pagenum )
  83         {
  84                 void    *old_pb = pb;
  85                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
  86                 if(!pb) {
  87                         Mutex_Release( &h->Node->Lock );
  88                         LEAVE_RET('n', NULL);
  89                 }
  90                 pb->Next = old_pb;
  91                 pb->BaseOffset = pagenum - pagenum % MMAP_PAGES_PER_BLOCK;
  92                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
  93                 if(prev)
  94                         prev->Next = pb;
  95                 else
  96                         h->Node->MMapInfo = pb;
  97         }
  98
  99         // - Map (and allocate) pages
 100         while( npages -- )
 101         {
 102                 if( MM_GetPhysAddr(mapping_dest) == 0 )
 103                 {
 104                         if( pb->PhysAddrs[pagenum - pb->BaseOffset] == 0 )
 105                         {
 106                                 if( h->Node->MMap )
 107                                         h->Node->MMap(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
 108                                 else
 109                                 {
 110                                          int    read_len;
 111                                         // Allocate pages and read data
 112                                         if( MM_Allocate(mapping_dest) == 0 ) {
 113                                                 // TODO: Unwrap
 114                                                 Mutex_Release( &h->Node->Lock );
 115                                                 LEAVE('n');
 116                                                 return NULL;
 117                                         }
 118                                         // TODO: Clip read length
 119                                         read_len = h->Node->Read(h->Node, pagenum*PAGE_SIZE, PAGE_SIZE, (void*)mapping_dest);
 120 //                                      if( read_len != PAGE_SIZE ) {
 121 //                                              memset( (void*)(mapping_dest+read_len), 0, PAGE_SIZE-read_len );
 122 //                                      }
 123                                 }
 124                                 pb->PhysAddrs[pagenum - pb->BaseOffset] = MM_GetPhysAddr( mapping_dest );
 125                                 MM_SetPageNode( pb->PhysAddrs[pagenum - pb->BaseOffset], h->Node );
 126                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 127                                 LOG("Read and map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 128                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 129                         }
 130                         else
 131                         {
 132                                 MM_Map( mapping_dest, pb->PhysAddrs[pagenum - pb->BaseOffset] );
 133                                 MM_RefPhys( pb->PhysAddrs[pagenum - pb->BaseOffset] );
 134                                 LOG("Cached map %X to %p (%P)", pagenum*PAGE_SIZE, mapping_dest,
 135                                         pb->PhysAddrs[pagenum - pb->BaseOffset]);
 136                         }
 137                         h->Node->ReferenceCount ++;
 138
 139                         // Set flags
 140                         if( !(Protection & MMAP_PROT_WRITE) ) {
 141                                 MM_SetFlags(mapping_dest, MM_PFLAG_RO, MM_PFLAG_RO);
 142                         }
 143                         else {
 144                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 145                         }
 146                 }
 147                 else
 148                 {
 149                         LOG("Flag update on %p", mapping_dest);
 150                         if( (MM_GetFlags(mapping_dest) & MM_PFLAG_RO) && (Protection & MMAP_PROT_WRITE) )
 151                         {
 152                                 MM_SetFlags(mapping_dest, 0, MM_PFLAG_RO);
 153                         }
 154                 }
 155                 if( Flags & MMAP_MAP_PRIVATE )
 156                         MM_SetFlags(mapping_dest, MM_PFLAG_COW, MM_PFLAG_COW);
 157                 pagenum ++;
 158                 mapping_dest += PAGE_SIZE;
 159
 160                 // Roll on to next block if needed
 161                 if(pagenum - pb->BaseOffset == MMAP_PAGES_PER_BLOCK)
 162                 {
 163                         if( pb->Next && pb->Next->BaseOffset == pagenum )
 164                                 pb = pb->Next;
 165                         else
 166                         {
 167                                 tVFS_MMapPageBlock      *oldpb = pb;
 168                                 pb = malloc( sizeof(tVFS_MMapPageBlock) );
 169                                 pb->Next = oldpb->Next;
 170                                 pb->BaseOffset = pagenum;
 171                                 memset(pb->PhysAddrs, 0, sizeof(pb->PhysAddrs));
 172                                 oldpb->Next = pb;
 173                         }
 174                         pagenum = 0;
 175                 }
 176         }
 177
 178         Mutex_Release( &h->Node->Lock );
 179
 180         LEAVE('p', mapping_base);
 181         return (void*)mapping_base;
 182 }
 183
 184 int VFS_MUnmap(void *Addr, size_t Length)
 185 {
 186         return 0;
 187 }